BACKGROUND OF THE INVENTION
FIELD OF THE INVENTION
[0001] The present invention relates to a ball screw used for various
industrial machines as well as a seal member and a seal structure applicable to
5 the ball screw.
DESCRIPTION OF THE BACKGROUND ART
[0002] Conventionally, there have been publicly well-known ball screw
devices each having a ball screw shaft and a ball nut fitted on an outer
10 periphery of the ball screw shaft, and each including: a lip-type seal member
having a lip part elastically contacting a periphery of the ball screw shaft at an
end of the ball nut; and a cylindrically-shaped wiper-type seal member having
a convex part on an inner periphery thereof, which convex part is fitted in
grooves of the ball screw shaft such that the cylindrically-shaped wiper-type
15 seal member is fitted on an outer periphery of the ball screw shaft on an outer
side of the lip-type seal member in an axial direction (see Patent Document 1).
Such a ball screw device including the lip-type seal member and the wire-type
seal member used in a combined manner is configured such that foreign
substances in the form of fine particles are prevented from entering between
20 the ball screw shaft and the ball nut.
[0003] Meanwhile, there have been publicly well-known seal members each
formed into the same in shape as the outer periphery of the ball screw shaft
(see Patent Document 2). Such seal members are configured such that thin
25 slide rings each made of synthetic resin are set on the outer periphery of the
ball screw shaft, and that outer peripheries of the slide rings are tightened by
back-up rings each made of synthetic rubber for the purpose of reduction of
sliding resistance when fitting the ball screw shaft in the seal members.
30 [0004] (Prior Art Documents)
(Patent Documents)
Patent Document 1: Japanese Patent Application Publication No.
2001-304372
Patent Document 2: Japanese Patent Application Publication No. H01-275953
35
[0005] (Problems to be Solved)
The ball screw device disclosed in Patent Document 1 can reduce the
entry of foreign substances between the ball screw shaft and the ball nut with
the lip-type seal members and the wiper-type seal members used in a
40 combined manner; nevertheless, there has been a problem that, when fitting
the ball screw shaft in the seal members, the slidability therebetween
3
deteriorates due to increase in sliding resistance therebetween.
[0006] Furthermore, there has been a problem that seal members disclosed in
Patent Document 2 have difficulties in evenly conforming the slide rings to
the outer periphery of the ball screw shaft due to non-5 contractility of the
synthetic resin, and that, when fitting the ball screw shaft in the seal members,
the slidability therebetween deteriorates due to increase in sliding resistance
therebetween caused by tightening with back-up rings made of synthetic
rubber even if the synthetic resin with high slidability is used.
10
SUMMARY OF THE INVENTION
[0007] The objective of the present invention is to provide a ball screw, a
seal member, and a seal structure for capable of effectively reducing the entry
of fine foreign substances between male and female components while
15 capable of decreasing the sliding resistance between the male component and
the seal member when fitting the male component in the seal member.
[0008] (Means for Solving Problems)
[1] A ball screw according to the present invention is characterized by
20 comprising: a male component having a plurality of male grooves formed on
an outer periphery thereof such that a ball is allowed to roll in the plurality of
male grooves; a female component having a plurality of female grooves facing
the plurality of male grooves formed on an inner periphery thereof such that
the ball is allowed to roll in the plurality of female grooves, and having a
25 circulation path formed therein such that the ball is allowed to circulate
through the circulation path; and a seal member arranged at one end, at the
other end, or at each of one and the other ends of the female component in an
axial direction, wherein the male and female components are fitted together in
the axial direction, and wherein the seal member includes a hole capable of
30 communicating with the inner periphery of the female component, a fiber
layer having a fitting surface formed with a convex part capable of being
fitted in the plurality of male grooves of the male component when the male
component is inserted into the hole, the fitting surface having at least a surface
made of fibers impregnated with rubber or resin, and a rubber or resin layer
35 laminated on a surface opposite to the fitting surface of the fiber layer.
[0009] According to the construction of [1] above, by virtue of making the
fiber layer, which is fitted with the plurality of male grooves of the male
component, of fibers impregnated with rubber or resin, the fibers can be
40 strongly bonded with rubber or resin, thereby not only maintaining the shape
of the convex part capable of being fitted in the plurality of male grooves of
the fiber layer but also accomplishing simultaneously the reduction of the
entry of fine foreign substances between the male and female components as
4
well as the reduction of the sliding resistance therebetween when shifting the
male and female components in a relative manner in an axial direction, both of
which reductions are trade-off related to each other. Further, by laminating
the rubber or resin layer for reinforcement on the surface of the fiber layer on
a side opposite to a hole-formed side, the shape of the 5 convex part of the fiber
layer can be stabilized, and the deformation of the fiber layer as a whole when
causing the ball screw to work can be reduced. Still further, by virtue of
laminating such a rubber or resin layer, the fiber and rubber or resin layers can
be stably fixed to the female component at one end or the other end thereof.
10
[0010] [2] Regarding another aspect, the ball screw according to the present
invention is characterized by comprising: a male component having a plurality
of male grooves formed on an outer periphery thereof such that a ball is
allowed to roll in the plurality of male grooves; a female component having a
15 plurality of female grooves facing the plurality of male grooves formed on an
inner periphery thereof such that the ball is allowed to roll in the plurality of
female grooves, and having a circulation path formed therein such that the ball
is allowed to circulate through the circulation path; and a seal member
arranged at one end, at the other end, or at each of one and the other ends of
20 the female component in an axial direction, wherein the male and female
components are fitted together in the axial direction, wherein the seal member
includes a hole capable of communicating with the inner periphery of the
female component, a fiber layer having a fitting surface formed with a convex
part capable of being fitted in the plurality of male grooves of the male
25 component when the male component is inserted into the hole, the fitting
surface having at least a surface made of fibers impregnated with rubber or
resin, and a rubber or resin layer laminated on a surface opposite to the fitting
surface of the fiber layer, and wherein a length of the fitting surface in the
axial direction is shorter than or equal to a pitch width (a distance between
30 threads adjacent to each other as a part of the male component) of the plurality
of male grooves of the male component.
[0011] According to the construction of [2] above, by virtue of making the
fiber layer, which is fitted with the plurality of male grooves of the male
35 component, of fibers impregnated with rubber or resin, the fibers can be
strongly bonded with rubber or resin, thereby not only maintaining the shape
of the convex part capable of being fitted in the plurality of male grooves of
the fiber layer but also accomplishing simultaneously the reduction of the
entry of fine foreign substances between the male and female components as
40 well as the reduction of the sliding resistance therebetween when shifting the
male and female components in a relative manner in an axial direction, both of
which reductions are trade-off related to each other. Further, by laminating
the rubber or resin layer for reinforcement on the surface of the fiber layer on
a side opposite to a hole-formed side, the shape of the convex part of the fiber
5
layer can be stabilized, and the deformation of the fiber layer as a whole when
causing the ball screw to work can be reduced. Still further, by virtue of
laminating such a rubber or resin layer, the fiber and rubber or resin layers can
be stably fixed to the female component at one end or the other end thereof.
Still further, by virtue of rendering the length of the fitting 5 surface in the axial
direction as being shorter than or equal to the pitch width of the plurality of
male grooves of the male component, the seal member becomes less rigid so
as to exhibit full flexibility, thereby promoting the fitting surface to follow the
surface of the male component. As a result, the ball screw according to the
10 present invention can ensure the improved sealing property by closing a gap
between the seal member and the male component even when causing the ball
screw to work.
[0012] [3] Regarding the ball screw according to [2] above, it is preferable
15 that, at said one end, at said the other end, or at said each of one and the other
ends of the female component in the axial direction, a plurality of seal
members, as the seal member, are arranged coaxially in series in a continuous
manner. A gap may be made between the seal members.
20 [0013] According to the construction of [3] above, the plurality of seal
members as the seal member according to [2] above arranged coaxially in
series in a continuous manner can achieve lower in rigidity than a single-piece
seal member having the same fitting surface in length in an axial direction as
the construction of [3] above. As a result, the slidability of the fitting surface
25 is improved in comparison with that of the single-piece seal member. The
seal members in the construction of [3] above are more flexible than the
single-piece seal member, and therefore the fitting surface of the seal
members in the construction of [3] above is promoted to follow the surface of
the male component in comparison with the single-piece seal member.
30 Furthermore, according to the construction of [3] above, the edges of the
respective seal members (on the side contacting the male component) are
configured such that dust and the like can be scraped off the surface of the
male component. In other words, the seal members according to the
construction of [3] above can reduce the entry of dust and the like into the ball
35 screw to a greater degree than the single-piece seal member does.
[0014] [4] Regarding another aspect, the ball screw according to the present
invention is characterized by comprising: a male component having a plurality
of male grooves formed on an outer periphery thereof such that a ball is
40 allowed to roll in the plurality of male grooves; a female component having a
plurality of female grooves facing the plurality of male grooves formed on an
inner periphery thereof such that the ball is allowed to roll in the plurality of
female grooves, and having a circulation path formed therein such that the ball
is allowed to circulate through the circulation path; and a seal member
6
arranged at one end, at the other end, or at each of one and the other ends of
the female component in an axial direction, wherein the male and female
components are fitted together in the axial direction, and wherein the seal
member includes a hole capable of communicating with the inner periphery of
the female component, a fiber layer configured such that 5 the fiber layer can be
fitted with the plurality of male grooves of the male component when the male
component is inserted into the hole, the fiber layer having at least one surface
made of fibers impregnated with rubber or resin, a first rubber or resin layer
laminated on a surface opposite to the at least one surface of the fiber layer,
10 and a second rubber or resin layer of water and/or oil repellency laminated
with a predetermined thickness on the at least one surface of the fiber layer.
[0015] According to the construction of [4] above, by virtue of the at least
one surface of the fiber layer, which can be fitted with the plurality of male
15 grooves of the male component when the male component is inserted into the
hole, of fibers impregnated with rubber or resin, the fibers can be strongly
bonded with rubber or resin, thereby not only maintaining the shape of the at
least one surface of the fiber layer but also accomplishing simultaneously the
reduction of the entry of fine foreign substances between the male and female
20 components as well as the reduction of the sliding resistance therebetween
when shifting the male and female components in a relative manner in an axial
direction, both of which reductions are trade-off related to each other.
Further, by laminating the rubber or resin layer for reinforcement on the
surface of the fiber layer on a side opposite to a hole-formed side, the shape of
25 the convex part of the fiber layer can be stabilized, and the deformation of the
fiber layer as a whole when causing the ball screw to work can be reduced.
Still further, by virtue of laminating such a rubber or resin layer, the fiber and
rubber or resin layers can be stably fixed to the female component at one end
or the other end thereof. Still further, by virtue of the second rubber or resin
30 layer of water and/or oil repellency laminated on the at least one surface of the
fiber layer, the entry of dust, grease, oil, and the like into the fiber layer as
well as the degradation of the fiber layer can be reduced. Still further, since
the surface friction coefficient of the second rubber or resin layer is lower than
the previous one, the second rubber or resin layer causes less sliding wear
35 between the male component and the seal members, thereby improving the
durability of the seal member(s), i.e., increasing the life of the seal member(s),
and eventually increasing the life of the ball screw.
[0016] [5] A seal member according to the present invention is characterized
40 in that a male component of the ball screw having a plurality of male grooves
formed on an outer periphery thereof such that a ball is allowed to roll in the
plurality of male grooves, and a female component of the ball screw having a
plurality of female grooves facing the plurality of male grooves formed on an
inner periphery thereof such that the ball is allowed to roll in the plurality of
7
female grooves, and having a circulation path formed therein such that the ball
is allowed to circulate through the circulation path, are fitted together in an
axial direction, and that the seal member comprises: a hole capable of
communicating with the inner periphery of the female component; a fiber
layer having a fitting surface formed with a convex 5 part capable of being
fitted in the plurality of male grooves of the male component when the male
component is inserted into the hole, the fitting surface having at least a surface
made of fibers impregnated with rubber or resin; and a rubber or resin layer
laminated on a surface opposite to the fitting surface of the fiber layer.
10
[0017] According to the construction of [5] above, in attempt to apply the
seal members according to the present invention to: the male component of
the ball screw having the plurality of male grooves formed on the outer
periphery thereof such that the ball is allowed to roll in the plurality of male
15 grooves; and the female component of the ball screw having the plurality of
female grooves facing the plurality of male grooves formed on the inner
periphery thereof such that the ball is allowed to roll in the plurality of female
grooves and having the circulation path formed therein such that the ball is
allowed to circulate through the circulation path, one can make the fiber layer,
20 which is on the fitting surface formed with the convex part, of fibers
impregnated with rubber or resin, thereby capable of strongly bonding the
fibers with rubber or resin, thereby capable of maintaining the shape of the
convex part of the fiber layer, and thereby capable of simultaneously reducing
the entry of fine foreign substances between the male and female components
25 as well as reducing the sliding resistance therebetween when shifting the male
and female components in a relative manner in an axial direction, both of
which are trade-off related to each other. Further, by laminating the rubber
or resin layer for reinforcement on the surface of the fiber layer on a side
opposite to a hole-formed side, one can stabilize the shape of the convex part
30 of the fiber layer, and reduce the deformation of the fiber layer as a whole
when causing the ball screw to work. Still further, by laminating such a
rubber or resin layer, the one can stably fix fiber and rubber or resin layers to
the female component at one end or the other end thereof.
35 [0018] [6] A seal member according to the present invention is characterized
in that a male component of the ball screw having a plurality of male grooves
formed on an outer periphery thereof such that a ball is allowed to roll in the
plurality of male grooves, and a female component of the ball screw having a
plurality of female grooves facing the plurality of male grooves formed on an
40 inner periphery thereof such that the ball is allowed to roll in the plurality of
female grooves, and having a circulation path formed therein such that the ball
is allowed to circulate through the circulation path, are fitted together in an
axial direction, and that the seal member comprises: a hole capable of
communicating with the inner periphery of the female component; a fiber
8
layer having a fitting surface formed with a convex part capable of being
fitted in the plurality of male grooves of the male component when the male
component is inserted into the hole, the fitting surface having at least a surface
made of fibers impregnated with rubber or resin; and a rubber or resin layer
laminated on a surface opposite to the fitting surface 5 of the fiber layer, and
that a length of the fitting surface in the axial direction is shorter than or equal
to a pitch width of the plurality of male grooves of the male component.
[0019] According to the construction of [6] above, in attempt to apply the
10 seal members according to the present invention to: the male component of
the ball screw having the plurality of male grooves formed on the outer
periphery thereof such that the ball is allowed to roll in the plurality of male
grooves; and the female component of the ball screw having the plurality of
female grooves facing the plurality of male grooves formed on the inner
15 periphery thereof such that the ball is allowed to roll in the plurality of female
grooves and having the circulation path formed therein such that the ball is
allowed to circulate through the circulation path, one can make the fiber layer,
which is on the fitting surface formed with the convex part, of fibers
impregnated with rubber or resin, thereby capable of strongly bonding the
20 fibers with rubber or resin, thereby capable of maintaining the shape of the
convex part of the fiber layer, and thereby capable of simultaneously reducing
the entry of fine foreign substances between the male and female components
as well as reducing the sliding resistance therebetween when shifting the male
and female components in a relative manner in an axial direction, both of
25 which are trade-off related to each other. Further, by laminating the rubber
or resin layer for reinforcement on the surface of the fiber layer on a side
opposite to a hole-formed side, one can stabilize the shape of the convex part
of the fiber layer, and reduce the deformation of the fiber layer as a whole
when causing the ball screw to work. Still further, by laminating such a
30 rubber or resin layer, the one can stably fix fiber and rubber or resin layers to
the female component at one end or the other end thereof. Still further, by
rendering the length of the fitting surface in the axial direction as being
shorter than or equal to the pitch width of the plurality of male grooves of the
male component, one can render the seal member as being less rigid so as to
35 exhibit full flexibility, thereby promoting the fitting surface to follow the
surface of the male component. As a result, by virtue of the ball screw
according to the present invention, one can improve sealing property by
closing a gap between the seal member and the male component even when
causing the ball screw to work.
40
[0020] [7] Regarding the seal member according to the present invention, a
plurality of seal members, as the seal member according to [6] above, may be
arranged coaxially in series in a continuous manner. A gap may be made
between the seal members.
9
[0021] According to the construction of [7] above, the plurality of seal
members as the seal member according to [6] above arranged coaxially in
series in a continuous manner can achieve lower in rigidity than a single-piece
seal member having the same fitting surface in length 5 in an axial direction as
the construction of [7] above. As a result, the slidability of the fitting surface
is improved in comparison with that of the single-piece seal member. The
seal members in the construction of [7] above are more flexible than the
single-piece seal member, and therefore the fitting surface of the seal
10 members in the construction of [7] above is promoted to follow the surface of
the male component in comparison with the single-piece seal member.
According to the construction of [7] above, the edges of the respective seal
members (on the side contacting the male component) are configured such
that dust and the like can be scraped off the surface of the male component.
15 In other words, the seal members according to the construction of [7] above
can reduce the entry of dust and the like into the ball screw to a greater degree
than the single-piece seal member does.
[0022] [8] A seal member according to the present invention is characterized
20 in that a male component of the ball screw having a plurality of male grooves
formed on an outer periphery thereof such that a ball is allowed to roll in the
plurality of male grooves, and a female component of the ball screw having a
plurality of female grooves facing the plurality of male grooves formed on an
inner periphery thereof such that the ball is allowed to roll in the plurality of
25 female grooves, and having a circulation path formed therein such that the ball
is allowed to circulate through the circulation path, are fitted together in an
axial direction, and that the seal member comprises: a hole capable of
communicating with the inner periphery of the female component; a fiber
layer configured such that the fiber layer can be fitted with the plurality of
30 male grooves of the male component when the male component is inserted
into the hole, the fiber layer having at least one surface made of fibers
impregnated with rubber or resin; a first rubber or resin layer laminated on a
surface opposite to the at least one surface of the fiber layer; and a second
rubber or resin layer of water and/or oil repellency laminated with a
35 predetermined thickness on the at least one surface of the fiber layer.
[0023] According to the construction [8] above, when applying the seal
members according to the present invention to a male component having a
plurality of male grooves formed on an outer periphery thereof in which a ball
40 is allowed to roll, and a female component having a plurality of female
grooves facing the plurality of male grooves formed on an inner periphery
thereof in which the ball is allowed to roll, and having a circulation path
through which the ball is allowed to circulate, by virtue of the at least one
surface of the fiber layer, which can be fitted with the plurality of male
10
grooves of the male component when the male component is inserted into the
hole, of fibers impregnated with rubber or resin, the fibers can be strongly
bonded with rubber or resin, thereby not only maintaining the shape of the at
least one surface of the fiber layer but also accomplishing simultaneously the
reduction of the entry of fine foreign substances between 5 the male and female
components as well as the reduction of the sliding resistance therebetween
when shifting the male and female components in a relative manner in an axial
direction, both of which reductions are trade-off related to each other.
Further, by laminating the rubber or resin layer for reinforcement on the
10 surface of the fiber layer on a side opposite to a hole-formed side, the shape of
the convex part of the fiber layer can be stabilized, and the deformation of the
fiber layer as a whole when causing the ball screw to work can be reduced.
Still further, by virtue of laminating such a rubber or resin layer, the fiber and
rubber or resin layers can be stably fixed to the female component at one end
15 or the other end thereof. Still further, by virtue of the second rubber or resin
layer of water and/or oil repellency laminated on the at least one surface of the
fiber layer, the entry of dust, grease, oil, and the like into the fiber layer as
well as the degradation of the fiber layer can be reduced. Still further, since
the surface friction coefficient of the second rubber or resin layer is lower than
20 the previous one, the second rubber or resin layer causes less sliding wear
between the male component and the seal members, thereby improving the
durability of the seal member(s), i.e., increasing the life of the seal member(s).
[0024] [9] A seal structure according to the present invention applied to a
25 ball screw is characterized in that a male component of the ball screw having a
plurality of male grooves formed on an outer periphery thereof such that a ball
is allowed to roll in the plurality of male grooves, and a female component of
the ball screw having a plurality of female grooves facing the plurality of male
grooves formed on an inner periphery thereof such that the ball is allowed to
30 roll in the plurality of female grooves, and having a circulation path formed
therein such that the ball is allowed to circulate through the circulation path,
are fitted together in an axial direction, and that the seal structure comprises: a
hole capable of communicating with the inner periphery of the female
component; and a fiber layer having a fitting surface formed with a convex
35 part capable of being fitted in the plurality of male grooves of the male
component when the male component is inserted into the hole, the fitting
surface having at least a surface made of fibers impregnated with rubber or
resin.
40 [0025] According to the construction of [9] above, by virtue of making the
fiber layer, which is on the fitting surface formed with the convex part, of
fibers impregnated with rubber or resin, the fibers can be strongly bonded
with rubber or resin, thereby capable of maintaining the shape of the convex
part of the fiber layer, and thereby capable of simultaneously reducing the
11
entry of fine foreign substances between the male and female components as
well as the sliding resistance therebetween when shifting the male and female
components in a relative manner in an axial direction, which entry and sliding
resistance are trade-off related to each other.
5
[0026] [10] A seal structure according to the present invention applied to a
ball screw is characterized in that a male component of the ball screw having a
plurality of male grooves formed on an outer periphery thereof such that a ball
is allowed to roll in the plurality of male grooves, and a female component of
the ball screw having a plurality of female grooves facing 10 the plurality of male
grooves formed on an inner periphery thereof such that the ball is allowed to
roll in the plurality of female grooves, and having a circulation path formed
therein such that the ball is allowed to circulate through the circulation path,
are fitted together in an axial direction, and that the seal structure comprises: a
15 hole capable of communicating with the inner periphery of the female
component; and a fiber layer having a fitting surface formed with a convex
part capable of being fitted in the plurality of male grooves of the male
component when the male component is inserted into the hole, the fitting
surface having at least a surface made of fibers impregnated with rubber or
20 resin, and that a length of the fitting surface in the axial direction is shorter
than or equal to a pitch width of the plurality of male grooves of the male
component.
[0027] According to the construction of [10] above, by virtue of making the
25 fiber layer, which is on the fitting surface formed with the convex part, of
fibers impregnated with rubber or resin, the fibers can be strongly bonded
with rubber or resin, thereby capable of maintaining the shape of the convex
part of the fiber layer, and thereby capable of simultaneously reducing the
entry of fine foreign substances between the male and female components as
30 well as the sliding resistance therebetween when shifting the male and female
components in a relative manner in an axial direction, which entry and sliding
resistance are trade-off related to each other.
[0028] [11] Regarding the seal structure according to the present invention, a
35 plurality of seal structures, as the seal structure according to [10] above, may
be arranged coaxially in series in a continuous manner. A gap may be made
between the seal structures.
[0029] According to the construction of [11] above, the plurality of seal
40 structures as the seal structure according to [10] above arranged coaxially in
series in a continuous manner can achieve lower in rigidity than a single-piece
seal structure having the same fitting surface in length in an axial direction as
the construction of [11] above. As a result, the slidability of the fitting
surface is improved in comparison with that of the single-piece seal structure.
12
The seal structures in the construction of [11] above are more flexible than the
single-piece seal structure, and therefore the fitting surface is promoted to
follow the surface of the male component in comparison with the single-piece
seal structure. According to the construction of [11] above, the edges of the
respective seal structures (on the side contacting 5 the male component) are
configured such that dust and the like can be scraped off the surface of the
male component. In other words, the seal structures according to the
construction of [11] above can reduce the entry of dust and the like into the
ball screw to a greater degree than the single-piece seal structure does.
10
[0030] [12] A seal structure according to the present invention is
characterized in that a male component of the ball screw having a plurality of
male grooves formed on an outer periphery thereof such that a ball is allowed
to roll in the plurality of male grooves, and a female component of the ball
15 screw having a plurality of female grooves facing the plurality of male
grooves formed on an inner periphery thereof such that the ball is allowed to
roll in the plurality of female grooves, and having a circulation path formed
therein such that the ball is allowed to circulate through the circulation path,
are fitted together in an axial direction, and that the seal structure comprises: a
20 hole capable of communicating with the inner periphery of the female
component; a fiber layer configured such that the fiber layer can be fitted with
the plurality of male grooves of the male component when the male
component is inserted into the hole, the fiber layer having at least one surface
made of fibers impregnated with rubber or resin; and a rubber or resin layer of
25 water and/or oil repellency laminated with a predetermined thickness on the at
least one surface of the fiber layer.
[0031] According to the construction of [12] above, by virtue of the at least
one surface of the fiber layer, which can be fitted with the plurality of male
30 grooves of the male component when the male component is inserted into the
hole, of fibers impregnated with rubber or resin, the fibers can be strongly
bonded with rubber or resin, thereby capable of maintaining the shape of the
at least one surface of the fiber layer. Further, it is possible to accomplish
simultaneously the reduction of the entry of fine foreign substances between
35 the male and female components as well as the reduction of the sliding
resistance therebetween when shifting the male and female components in a
relative manner in an axial direction, both of which reductions are trade-off
related to each other. Still further, by virtue of the rubber or resin layer of
water and/or oil repellency laminated on the at least one surface of the fiber
40 layer, the entry of dust, grease, oil, and the like into the fiber layer as well as
the degradation of the fiber layer can be reduced. Still further, since the
surface friction coefficient of the rubber or resin layer is lower than the
previous one, the rubber or resin layer causes less sliding wear between the
male component and the seal structures, thereby improving the durability of
13
the seal structure(s), i.e., increasing the life of the seal structure(s), and
eventually increasing the life of the ball screw.
BRIEF DESCRIPTION OF THE DRAWINGS
[0032] For more thorough understanding of the 5 present invention and
advantages thereof, the following descriptions should be read in conjunction
with the accompanying drawings, in which:
FIG. 1 depicts an example of perspective view showing a schematic
structure of a ball screw in a first embodiment of the present invention.
10 FIG. 2 depicts an example of explanatory view showing the internal
structures of the female component and seal members in the first embodiment.
FIG. 3 depicts an example of perspective view of the male component
of the ball screw in the first embodiment.
FIG. 4 depicts an example of perspective view of the female
15 component of the ball screw in the first embodiment.
FIG. 5 depicts an example of perspective view of the seal members of
the ball screw in the first embodiment.
FIG. 6 depicts an example of perspective view showing a schematic
structure of the ball screw in a second embodiment of the present invention.
20 FIG. 7 depicts an example of explanatory view showing the internal
structures of the female component and seal members in the second
embodiment.
FIG. 8 depicts an example of perspective view of the male component
of the ball screw in the second embodiment.
25 FIG. 9 depicts an example of perspective view of the female
component of the ball screw in the second embodiment.
FIG. 10 depicts an example of perspective view of the seal members
of the ball screw in the second embodiment.
FIG. 11 depicts an example of perspective view showing a schematic
30 structure of a ball screw in a third embodiment of the present invention.
FIG. 12 depicts an example of explanatory view showing the internal
structures of the female component and seal members in the third
embodiment.
FIG. 13 depicts an example of perspective view of the male
35 component of the ball screw in the third embodiment.
FIG. 14 depicts an example of perspective view of the female
component of the ball screw in the third embodiment.
FIG. 15 depicts an example of perspective view of the seal members
of the ball screw in the third embodiment.
40
DESCRIPTION OF EMBODIMENTS OF THE INVENTION
[0033] (First Embodiment)
14
Hereinafter, the ball screw in the first embodiment of the present
invention will be described with reference to FIGS. 1-5. Regarding a pair of
seal members (4) shown in FIG. 2 not necessarily needed to be explained
separately, it is to be noted that each of the parts is provided with a reference
numeral with respect to one seal member (4) (on the 5 left), while reference
numerals are appropriately omitted for some parts with respect to the other
seal member (4) (on the right), for the sake of simplification.
[0034] The ball screw (1), as shown in FIGS. 1 and 2, includes a male
10 component (2), a female component (3), and a pair of seal members (4).
[0035] The male component (2) is metallic and, as shown in FIG. 3, has a
rod-shaped main body part (5) and a plurality of male grooves (7) formed in a
spiral manner on the outer periphery (6) of the main body part (5).
15
[0036] The female component (3) is metallic and, as shown in FIG. 4, has a
cylindrical part (8) in a cylindrical shape, and a platy part (9) in a platy shape
formed on an end of the cylindrical part (8). The cylindrical part (8) and the
platy part (9) are integrally molded. As shown in FIG. 2, a plurality of
20 female grooves (12) are formed on the inner peripheries (10, 11) of the
cylindrical part (8) and the platy part (9). Each female groove (12) is spirally
formed in a similar manner to each male groove (7), and formed at a position
where the female groove (12) faces the male groove (7) of the male
component (2) as shown in FIG. 2. Further, as shown in FIG. 2, circulation
25 paths (13), through which a plurality of balls B can circulate, are formed
inside the cylindrical part (8), and paths P capable of communicating with the
circulation paths (13) are formed between the male grooves (7) and the female
grooves (12). The paths P are filled with the plurality of balls B.
30 [0037] The ball screw (1) in this embodiment is configured as an endless
circulation path such that the relative rotation of the male and female
components (2, 3) allows the balls B to roll through the paths P and thereafter
return to an original position through the circulation paths (13). Such
circulation of the balls B is performed in a repetitive manner, which enables
35 the male and female components (2, 3) to shift in a relative manner in an axial
direction while being fitted together. The male grooves (7) in this
embodiment are formed in a four thread screw structure. In other words, the
number of threads with respect to the grooves is four, and therefore four
circulation paths (13) are formed accordingly.
40
[0038] As shown in FIG. 2, each of the seal members (4) includes a fiber
layer (14), a resin layer (15), and a cover member (16).
[0039] The fiber layer (14) may be made of, e.g., aramid fiber, nylon,
15
urethane, cotton, silk, linen, acetate, rayon, fluorine-containing fiber, polyester,
or the like, which are impregnated with rubber or resin. The fiber layer (14)
may be made of e.g. short fibers and long fibers.
[0040] By virtue of impregnating fibers with rubber or 5 resin, rubber material
or resin material is enabled to penetrate into the gaps within the fibers, and to
serve as fiber layer (14) so as to bond these fibers. Further, by virtue of
impregnating fibers with rubber and the like, the wear caused by friction
between the fibers can be reduced, and still further, the resistance to wear on
10 the fiber layer (14) caused by friction between the fiber layer (14) and male
component (2) can be improved.
[0041] The rubber is required to be that with which the fibers can be
impregnated. As such types of rubber, the followings may be used in a neat
15 form or in a form denatured in various ways: e.g., urethane rubber, nitrile
rubber, silicon rubber, fluororubber, acrylic rubber, ethylene-propylene rubber,
butyl rubber, isoprene rubber, chlorinated polyethylene rubber,
epichlorohydrin rubber, hydrogenated nitrile rubber, chloroprene rubber,
polybutadiene rubber, styrene-butadiene rubber, natural rubber, and the like.
20 Each of these types of rubber may be used alone, or a plurality of types of
rubber selected therefrom may be used in a blended form. Further, the
rubber may contain appropriate amounts of traditional compounding
ingredients for rubber, such as vulcanizing agent, vulcanizing accelerator,
antioxidant, softener, plasticizer, filler, colorant, and the like as well as solid
25 lubricants such as graphite, silicone oil, fluorine powder, molybdenum
disulfide, or the like for enhancing the lubricity of the fiber layer (14). Still
further, the above types of rubber may be replaced by or combined with
thermoplastic or thermosetting resin such as acrylic resin, polyester resin,
urethane resin, vinyl chloride resin, polypropylene, polycarbonate,
30 polyethylene terephthalate resin, fluorine resin, polyethylene,
acrylonitrile-styrene resin, acrylonitrile-butadiene-styrene resin, polystyrene
resin, polyvinyl chloride, polyvinylidene chloride, polyvinyl acetate, nylon,
alkyd resin, phenolic resin, epoxy resin, polyphenylene sulfide resin, and the
like.
35
[0042] When impregnating fibers with rubber or resin as described above, it
is preferable that the rubber or resin be dissolved by a solvent or another
means into a liquid state before dipping the predetermined fibers (short or
long fibers) in the liquid. The sheet-like fabric made of the fibers may be
40 used as a precursor of the fiber layer (14). This fabric is impregnated with
rubber or resin in the same way as mentioned above.
[0043] The fabric may be, e.g., non-woven fabric made of irregularly tangled
fibers, regularly-formed woven, knitted fabric, or the like. These fabrics are
16
characterized by facilitating impregnation (easier handling) with rubber and
the like, and further facilitating adhesion to the surface of the cover member
(16) in comparison with those made of fibers (short or long fibers) only,
because these fabrics are in sheet form. The woven fabric may be made in a
plain weave, satin weave, twill 5 weave, or the like.
[0044] The fabric may preferably be stretchy to some extent. By virtue of
such stretchiness, when the fabric is formed so as to be in line with the male
grooves (7) in shape, there can be achieved the advantageous effects that: the
10 surface of the fabric can easily be shaped in accordance with the form of the
male grooves (7); and the fiber layer (14) has the surface subjected to few
creases and uniformly finished, thereby enabling smooth fitting between the
male component (2) and the seal members (4), and further enabling decrease
in sliding resistance therebetween. By producing the fiber layer (14) of the
15 fabric in such a manner that a stretchiness direction of the fabric in particular
can coincide with at least a height direction (an axial direction of the ball
screw) of the cylindrically-shaped fiber layer (14), it becomes possible that
the surface of the fiber layer (14) is subjected to fewer creases.
20 [0045] The fiber layer (14), as shown in FIG. 5, is a cylindrically-shaped
layer having a hole (14a) defined therein. As shown in FIG. 2, the hole (14a)
is configured such that it communicates with the inner peripheries (10, 11) of
the female component (3). The fiber layer (14) includes an inner periphery
(fitting surface) (14b) arranged at a position where it surrounds the hole (14a),
25 and a convex part 14c formed on the inner periphery (14b). The convex part
(14c) is arranged on a region such that, when inserting the male component
(2) into the hole (14a), the convex part (14c) can be fitted in the male grooves
(7) of the male component (2) inserted into the hole (14a).
30 [0046] As the resin layer (15), e.g. urethane rubber, nitrile rubber, silicon
rubber, fluororubber, acrylic rubber, ethylene-propylene rubber, butyl rubber,
isoprene rubber, chlorinated polyethylene rubber, epichlorohydrin rubber,
hydrogenated nitrile rubber, chloroprene rubber, polybutadiene rubber,
styrene-butadiene rubber, natural rubber, and the like may be used in a neat
35 form or in a form denatured in various ways, or alternatively, acrylic resin,
polyester resin, urethane resin, vinyl chloride resin, polypropylene,
polycarbonate, polyethylene terephthalate resin, fluorine resin, and the like
may be used.
40 [0047] The resin layer (15) is a cylindrically-shaped layer having a hole
defined therein, and the outer peripheral portion of the fiber layer (14) can be
inserted into such a hole. As shown in FIG. 2, the resin layer (15) is
laminated on a surface (14d) on a side opposite to an inner-periphery
(14b)-formed side with respect to the fiber layer (14), where the
17
inner-periphery (14b)-formed side is indicative of a side of the fiber layer (14)
at which the inner periphery (14b) is formed.
[0048] A back-up ring may be installed on the outer peripheral portion of the
resin layer (15) so as to apply inward pressure to the inner 5 periphery (14b) of
the fiber layer, thereby enabling improvements in the sealing property. The
back-up ring, such as O-ring, garter spring, and the like, is configured to be
capable of applying inward pressure to the inner periphery (14b) of the fiber
layer, and it is preferable to select a type of back-up ring capable of generating
10 inward pressure of proper magnitude optimized with respect to a balance
between the sealing property and the slidability.
[0049] The cover member (16) is made of e.g. plastic or metal and, as shown
in FIG. 5, includes a cylindrical part (16a), a ring part (16b), and a ring-shaped
15 installation part (16c), all of which are integrally molded.
[0050] Further, the cover member (16) may be adhered to the fiber layer (14)
or the resin layer (15) with adhesives: e.g. acrylic resin adhesive, olefin
adhesive, urethane resin adhesive, ethylene-vinyl acetate resin adhesive,
20 epoxy resin adhesive, vinyl chloride resin adhesive, chloroprene rubber
adhesive, cyanoacrylate adhesive, silicon adhesive, styrene-butadiene rubber
adhesive, nitrile rubber adhesive, hot-melt adhesive, phenolic resin adhesive,
melamine resin adhesive, urea resin adhesive, resorcinol adhesive, or the like.
There are methods to cure an adhesive for bonding: by heating an adhesive so
25 as to cause the adhesive to melt as fluid, applying the melting adhesive, and
thereafter cooling the applied adhesive; just by heating an adhesive; or the like.
As possible surfaces to be bonded, e.g., contacting surfaces of the cylindrical
part (16a) and the resin layer (15) of the cover member, contacting surfaces of
the ring part (16b) and the resin layer (15) of the cover member, or the like
30 may be considered.
[0051] As shown in FIG. 2, the cylindrical part (16a) is placed on the surface
(15b) on a side opposite to the surface (15a) at a fiber-layer (14)-formed side
with respect to the resin layer (15), where the fiber-layer (14)-formed side is
35 indicative of a side of the resin layer (15) at which the fiber layer (14) is
formed. As shown in FIG. 2, the ring part (16b) is placed at one end of the
cylindrical part (16a), and is configured such that surfaces (14f, 15d) on a side
opposite to the surfaces (14e, 15c) at a female-component (3)-formed side
with respect to the fiber layer (14) and the resin layer (15), respectively, are
40 covered by the ring part (16b), where the female-component (3)-formed side
is indicative of a side of the fiber layer (14) and the resin layer (15) at which
the female component (3) is formed.
18
[0052] As shown in FIG. 2, the installation part (16c) is placed at the other
end of the cylindrical part (16a). The installation part (16c) is configured
such that the fiber layer (14) and the resin layer (15) covered by the
cylindrical part (16a) and the ring part (16b) can be installed by use of
fastening components (not shown) at each of 5 both ends of the female
component (3) in an axial direction.
[0053] The cover member (16) shall not be limited to the above form but
may be configured in other forms as long as such forms allow the installation
10 thereof at an end of the female component (3) in an axial direction. As such
other forms, e.g., the fiber layer (14) and the resin layer (15) can be installed
by use of fastening components (not shown) at one end or each of both ends of
the female component (3) in the axial direction in such a manner that these
layers are fitted in a bore formed at one end or each of both ends of the female
15 component (3) in the axial direction before a platy cover member having a
hole for allowing the male component (2) to pass therethrough is adhered to a
side surface of the resin layer (15).
[0054] If the fiber layer (14) and the resin layer (15) are fitted in the bore
20 formed at one end or each of both ends of the female component (3) in the
axial direction as mentioned above and thereafter fixation screws (not shown)
are drive-fitted from the cylindrical part (8) or the outer peripheral portion of
the platy part (9) of the female component (3) to the resin layer (15), there are
cases where the cover member (16) may not be needed.
25
[0055] The seal members (4) may be manufactured by performing
successively the steps of, in one example: wrapping sheet-like woven fabric
impregnated with rubber or the like around the outer periphery (6) of the male
component (2) to form a precursor layer of the fiber layer (14); wrapping a
30 sheet of resin around the outer periphery of the precursor layer of the fiber
layer (14) to form a precursor layer of the resin layer (15); applying pressure
of proper magnitude on the outer periphery of the precursor layer of the resin
layer (15) to form a convex part (14c) on the inner periphery of the precursor
layer of the fiber layer (14); removing the precursor layers of the fiber layer
35 (14) and the resin layer (15) from the male component (2) by rotating them in
a circumferential direction of the male component (2); cutting the precursor
layers of the fiber layer (14) and the resin layer (15) into doughnut-shaped
pieces to make the fiber layer (14) and the resin layer (15) from each piece;
and adhering the cover member (16) to the fiber layer (14) and the resin layer
40 (15) with adhesive. Obviously, if no cover member is needed, the cover
member adhering step is omitted.
[0056] (Examples)
19
Next, the present invention will be specifically explained with
reference to examples. The following descriptions are provided for the
results of material tests prescribed in Japanese Industrial Standards (JIS) for
examining the usefulness of the fiber layer (14) in an embodiment (see FIG. 2)
as a buffer member. It is to be noted that the present 5 invention shall not be
limited to this example. More specifically, the inventors have conducted the
Pico abrasion test (JIS K 6264-2) as well as the friction coefficient
measurement test (JIS K 7125) using a Heidon tester to compare between
nylon 66 impregnated with nitrile rubber and single-component rubber
10 material made of nitrile rubber (hardness 70, JIS K 6253, Type A Durometer).
[0057] Table 1 below shows the results of the Pico abrasion test, and Table 2
below shows the results of the friction coefficient measurement test. In
Tables 1, 2, the item “Rubber-impregnated” denotes material contained in the
15 fiber layer (14) of this embodiment, more specifically, the nylon 66
impregnated with nitrile rubber, and the item “Single-component rubber”
denotes the single-component rubber material made of nitrile rubber for
comparison with the material contained in the fiber layer (14) of this
embodiment.
20
Table 1
Abrasion loss
Rubber-impregnated 2.2 mg
Single-component rubber 9.9 mg
Table 2
Friction coefficient
Rubber-impregnated 0.54
Single-component rubber 1.48
25 [0058] As shown in Table 1, the abrasion loss is 2.2 mg in the nylon 66
impregnated with nitrile rubber, and is 9.9 mg in the single-component rubber
material made of nitrile rubber. It is therefore found that the abrasion loss
can be reduced to approximately one-fifth in the nylon 66 impregnated with
nitrile rubber as compared to the single-component rubber material.
30
[0059] As shown in Table 2, the friction coefficient is 0.54 in the nylon 66
impregnated with nitrile rubber, and is 1.48 in the single-component rubber
material made of nitrile rubber. It is found therefore that the friction
coefficient can be reduced to approximately one-third in the nylon 66
35 impregnated with nitrile rubber as compared to the single-component rubber
material.
20
[0060] These results demonstrate the superiority of the nylon 66 impregnated
with nitrile rubber as a buffer. More specifically, the results show that the
single-component rubber material formed on the outer peripheral portion of
the male component (2) can indeed reduce the tooth-hit noise generated
between the male and female components (2, 3), while 5 increases the sliding
resistance (the friction coefficient is increased). Meanwhile, the fiber layer
(14) containing the nylon 66 impregnated with nitrile rubber formed on the
outer peripheral portion of the male component (2) can reduce the sliding
resistance (the friction coefficient is decreased more than that of the
10 single-component rubber material formed on the outer peripheral portion of
the male component (2)), and can improve the durability (the abrasion loss is
decreased further than that of the single-component rubber material formed on
the outer peripheral portion of the male component (2)).
15 [0061] (Features of ball screw of first embodiment)
According to the above construction, by virtue of making the fiber
layer (14), which is fitted with the male grooves (7) of the male component
(2), of woven fabric impregnated with rubber or the like, there can be
simultaneously accomplished the reduction of the entry of fine foreign
20 substances between the male and female components (2, 3) as well as the
reduction of the sliding resistance therebetween when shifting them in a
relative manner in an axial direction, both of which reductions as two
problems are trade-off related to each other. Further, the fiber layer (14)
impregnated with rubber or the like can improve the resistance to wear on the
25 surface of the fiber layer (14) caused by friction generated between the fiber
layer (14) and the male component (2). Still further, by laminating the resin
layer (15) for reinforcing the fiber layer (14) on the surface (14d) opposite to
the surface (14b) on which a hole (14a) is formed with respect to the fiber
layer (14), the fiber layer (14) and the resin layer (15) can be stably fixed to
30 the female component (3) at both ends thereof through the use of the cover
member (16).
[0062] Specific constructions according to the present invention are not
limited to the first embodiment described above with reference to the
35 drawings. The scope of the present invention is not encompassed by the
above explanations of the embodiment but particularly pointed out by the
claims, and the equivalents of the claim recitations as well as all the
modifications within the scope of the claims fall within the scope of the
present invention.
40
[0063] For example, in the first embodiment, there is described an example
of arranging a pair of seal members (4) at both ends of the female component
(3), respectively, in the axial direction; however, the present invention shall
not be limited to such an example, and a seal member (4) may be arranged at
21
any one of the two ends of the female component (3) in the axial direction, in
accordance with the usage circumstances.
[0064] The first embodiment shows an example of male grooves (7) of a
male component (2) having four thread screw structure, 5 but the present
invention shall not be limited to the example, and the number of threads of the
male grooves (7) may be changed in accordance with the usage circumstances
of the ball screw (1).
10 [0065] In the first embodiment, there is described an example of
impregnating fibers of the fiber layer (14) with rubber or the like; however,
the present invention shall not be limited to such an example, and the fibers
are required to be those which can be impregnated with rubber or the like and
which have low sliding resistance against the metal surface, and sheet-like
15 fabric made of fibers may be used for the fiber layer (14). For example,
canvas, velvet, denim, woven fabric, knitted fabric impregnated with rubber or
the like may be used. Horizontally and/or vertically stretchy fibers may also
be used.
20 [0066] (Second Embodiment)
Hereinafter, the ball screw in the first embodiment of the present
invention will be described with reference to FIGS. 6-10. Regarding a pair
of seal members (104) shown in FIG. 7 not necessarily needed to be explained
separately, it is to be noted that each of the parts is provided with a reference
25 numeral with respect to one seal member (104) (on the left), while reference
numerals are appropriately omitted for some parts with respect to the other
seal member (104) (on the right), for the sake of simplification.
[0067] The ball screw (101), as shown in FIGS. 6 and 7, includes a male
30 component (102), a female component (103), and a pair of seal members
(104).
[0068] The male component (102) is metallic and, as shown in FIG. 8, has a
rod-shaped main body part (105) and a plurality of male grooves (107) formed
35 in a spiral manner on the outer periphery (106) of the main body part (105).
[0069] The female component (103) is metallic and, as shown in FIG. 9, has
a cylindrical part (108) in a cylindrical shape, and a platy part (109) in a platy
shape formed on an end of the cylindrical part (108). The cylindrical part
40 (108) and the platy part (109) are integrally molded. As shown in FIG. 7, a
plurality of female grooves (112) are formed on the inner peripheries (110,
111) of the cylindrical part (108) and the platy part (109). Each female
groove (112) is spirally formed in a similar manner to each male groove (107),
and formed at a position where the female groove (112) faces the male groove
22
(107) of the male component (102) as shown in FIG. 7. Further, as shown in
FIG. 7, circulation paths (113), through which a plurality of balls B1 can
circulate, are formed inside the cylindrical part (108), and paths P1 capable of
communicating with the circulation paths (113) are formed between the male
grooves (107) and the female grooves (112). The paths 5 P are filled with the
plurality of balls B1.
[0070] The ball screw (101) in this embodiment is configured as an endless
circulation path such that the relative rotation of the male and female
10 components (102, 103) allows the balls B1 to roll through the paths P1 and
thereafter return to an original position through the circulation paths (113).
Such circulation of the balls B1 is performed in a repetitive manner, which
enables the male and female components (102, 103) to shift in a relative
manner in an axial direction while being fitted together. The male grooves
15 (107) in this embodiment are formed in a four thread screw structure. In
other words, the number of threads with respect to the grooves is four, and
therefore four circulation paths (113) are formed accordingly.
[0071] As shown in FIG. 7, each of the seal members (104) includes a fiber
20 layer (114), a resin layer (115), and a cover member (116).
[0072] The fiber layer (114) may be made of, e.g., aramid fiber, nylon,
urethane, cotton, silk, linen, acetate, rayon, fluorine-containing fiber, polyester,
or the like, which are impregnated with rubber or resin. The fiber layer (114)
25 may be made of e.g. short fibers and long fibers.
[0073] By virtue of impregnating fibers with rubber or resin, rubber material
or resin material is enabled to penetrate into the gaps within the fibers, and to
serve as fiber layer (114) so as to bond these fibers. Further, by virtue of
30 impregnating fibers with rubber and the like, the wear caused by friction
between the fibers can be reduced, and still further, the resistance to wear on
the fiber layer (114) caused by friction between the fiber layer (114) and male
component (102) can be improved.
35 [0074] The rubber is required to be that with which the fibers can be
impregnated. As such types of rubber, the followings may be used in a neat
form or in a form denatured in various ways: e.g., urethane rubber, nitrile
rubber, silicon rubber, fluororubber, acrylic rubber, ethylene-propylene rubber,
butyl rubber, isoprene rubber, chlorinated polyethylene rubber,
40 epichlorohydrin rubber, hydrogenated nitrile rubber, chloroprene rubber,
polybutadiene rubber, styrene-butadiene rubber, natural rubber, and the like.
Each of these types of rubber may be used alone, or a plurality of types of
rubber selected therefrom may be used in a blended form. Further, the
rubber may contain appropriate amounts of traditional compounding
23
ingredients for rubber, such as vulcanizing agent, vulcanizing accelerator,
antioxidant, softener, plasticizer, filler, colorant, and the like as well as solid
lubricants such as graphite, silicone oil, fluorine powder, molybdenum
disulfide, or the like for enhancing the lubricity of the fiber layer (114). Still
further, the above types of rubber may be replaced 5 by or combined with
thermoplastic or thermosetting resin such as acrylic resin, polyester resin,
urethane resin, vinyl chloride resin, polypropylene, polycarbonate,
polyethylene terephthalate resin, fluorine resin, polyethylene,
acrylonitrile-styrene resin, acrylonitrile-butadiene-styrene resin, polystyrene
10 resin, polyvinyl chloride, polyvinylidene chloride, polyvinyl acetate, nylon,
alkyd resin, phenolic resin, epoxy resin, polyphenylene sulfide resin, and the
like.
[0075] When impregnating fibers with rubber or resin as described above, it
15 is preferable that the rubber or resin be dissolved by a solvent or another
means into a liquid state before dipping the predetermined fibers (short fibers,
long fibers, fabric) in the liquid. The sheet-like fabric made of the fibers
may be used as a precursor of the fiber layer (114). This fabric is
impregnated with rubber or resin in the same way as mentioned above.
20
[0076] The fabric may be, e.g., non-woven fabric made of irregularly tangled
fibers, regularly-formed woven, knitted fabric, or the like. These fabrics are
characterized by facilitating impregnation (easier handling) with rubber and
the like, and further facilitating adhesion to the surface of the cover member
25 (116) in comparison with those made of fibers (short or long fibers) only,
because these fabrics are in sheet form. The woven fabric may be made in a
plain weave, satin weave, twill weave, or the like.
[0077] The fabric may preferably be stretchy to some extent. By virtue of
30 such stretchiness, when the fabric is formed so as to be in line with the male
grooves (107) in shape, there can be achieved the advantageous effects that:
the surface of the fabric can easily be shaped in accordance with the form of
the male grooves (107); and the fiber layer (114) has the surface subjected to
few creases and uniformly finished, thereby enabling smooth fitting between
35 the male component (102) and the seal members (104), and further enabling
decrease in sliding resistance therebetween. By producing the fiber layer
(114) of the fabric in such a manner that a stretchiness direction of the fabric
in particular can coincide with at least a height direction (an axial direction of
the ball screw) of the cylindrically-shaped fiber layer (114), it becomes
40 possible that the surface of the fiber layer (114) is subjected to fewer creases.
[0078] The fiber layer (114), as shown in FIG. 10, is a cylindrically-shaped
layer having a hole (114a) defined therein. As shown in FIG. 7, the hole
(114a) is configured such that it communicates with the inner peripheries (110,
24
111) of the female component (103). The fiber layer (114) includes an inner
periphery (fitting surface) (114b) arranged at a position where it surrounds the
hole (114a), and a convex part (114c) formed on the inner periphery (114b).
The convex part (114c) is arranged on a region such that, when inserting the
male component (102) into the hole (114a), the convex 5 part (114c) can be
fitted in the male grooves (107) of the male component (102) inserted into the
hole (114a). It is to be noted that the fiber layer (114) is configured such that
a length of the inner periphery (114b) in the axial direction (a longitudinal
direction of the male component (102)) is shorter than or equal to a pitch
10 width of the male grooves (107) of the male component (102).
[0079] As the resin layer (115), e.g. urethane rubber, nitrile rubber, silicon
rubber, fluororubber, acrylic rubber, ethylene-propylene rubber, butyl rubber,
isoprene rubber, chlorinated polyethylene rubber, epichlorohydrin rubber,
15 hydrogenated nitrile rubber, chloroprene rubber, polybutadiene rubber,
styrene-butadiene rubber, natural rubber, and the like may be used in a neat
form or in a form denatured in various ways, or alternatively, acrylic resin,
polyester resin, urethane resin, vinyl chloride resin, polypropylene,
polycarbonate, polyethylene terephthalate resin, fluorine resin, and the like
20 may be used.
[0080] The resin layer (115) is a cylindrically-shaped layer having a hole
defined therein, and the outer peripheral portion of the fiber layer (114) can be
inserted into such a hole. As shown in FIG. 7, the resin layer (115) is
25 laminated on a surface (114d) on a side opposite to an inner-periphery
(114b)-formed side with respect to the fiber layer (114), where the
inner-periphery (114b)-formed side is indicative of a side of the fiber layer
(114) at which the inner periphery (114b) is formed.
30 [0081] A back-up ring may be installed on the outer peripheral portion of the
resin layer (115) so as to apply inward pressure to the inner periphery (114b)
of the fiber layer, thereby enabling improvements in the sealing property.
The back-up ring, such as O-ring, garter spring, and the like, is configured to
be capable of applying inward pressure to the inner periphery (114b) of the
35 fiber layer, and it is preferable to select a type of back-up ring capable of
generating inward pressure of proper magnitude optimized with respect to a
balance between the sealing property and the slidability.
[0082] The cover member (116) is made of e.g. plastic or metal and, as
40 shown in FIG. 10, includes a cylindrical part (116a), a ring part (116b), and a
ring-shaped installation part (116c), all of which are integrally molded.
[0083] Further, the cover member (116) may be adhered to the fiber layer
(114) or the resin layer (115) with adhesives: e.g. acrylic resin adhesive, olefin
25
adhesive, urethane resin adhesive, ethylene-vinyl acetate resin adhesive,
epoxy resin adhesive, vinyl chloride resin adhesive, chloroprene rubber
adhesive, cyanoacrylate adhesive, silicon adhesive, styrene-butadiene rubber
adhesive, nitrile rubber adhesive, hot-melt adhesive, phenolic resin adhesive,
melamine resin adhesive, urea resin adhesive, resorcinol 5 adhesive, or the like.
There are methods to cure an adhesive for bonding: by heating an adhesive so
as to cause the adhesive to melt as fluid, applying the melting adhesive, and
thereafter cooling the applied adhesive; just by heating an adhesive; or the like.
As possible surfaces to be bonded, e.g., contacting surfaces of the cylindrical
10 part (116a) and the resin layer (115) of the cover member, contacting surfaces
of the ring part (116b) and the resin layer (115) of the cover member, or the
like may be considered.
[0084] As shown in FIG. 7, the cylindrical part (116a) is placed on the
15 surface (115b) on a side opposite to the surface (115a) at a fiber-layer
(114)-formed side with respect to the resin layer (115), where the fiber-layer
(114)-formed side is indicative of a side of the resin layer (115) at which the
fiber layer (114) is formed. As shown in FIG. 7, the ring part (116b) is
placed at one end of the cylindrical part (116a), and is configured such that
20 surfaces (114f, 115d) on a side opposite to the surfaces (114e, 115c) at a
female-component (103)-formed side with respect to the fiber layer (114) and
the resin layer (115), respectively, are covered by the ring part (116b), where
the female-component (103)-formed side is indicative of a side of the fiber
layer (114) and the resin layer (115) at which the female component (103) is
25 formed.
[0085] As shown in FIG. 7, the installation part (116c) is placed at the other
end of the cylindrical part (116a). The installation part (116c) is configured
such that the fiber layer (114) and the resin layer (115) covered by the
30 cylindrical part (116a) and the ring part (116b) can be installed by use of
fastening components (not shown) at each of both ends of the female
component (103) in an axial direction.
[0086] The cover member (116) shall not be limited to the above form but
35 may be configured in other forms as long as such forms allow the installation
thereof at an end of the female component (103) in an axial direction. As
such other forms, e.g., the fiber layer (114) and the resin layer (115) can be
installed by use of fastening components (not shown) at one end or each of
both ends of the female component (103) in the axial direction in such a
40 manner that these layers are fitted in a bore formed at one end or each of both
ends of the female component (103) in the axial direction before a platy cover
member having a hole for allowing the male component (102) to pass
therethrough is adhered to a side surface of the resin layer (115).
26
[0087] If the fiber layer (114) and the resin layer (115) are fitted in the bore
formed at one end or each of both ends of the female component (103) in the
axial direction as mentioned above and thereafter fixation screws (not shown)
are drive-fitted from the cylindrical part (108) or the outer peripheral portion
of the platy part (109) of the female component (103) to 5 the resin layer (115),
there are cases where the cover member (116) may not be needed.
[0088] The seal members (104) may be manufactured by performing
successively the steps of, in one example: wrapping sheet-like woven fabric
10 impregnated with rubber or the like around the outer periphery (106) of the
male component (102) to form a precursor layer of the fiber layer (114);
wrapping a sheet of resin around the outer periphery of the precursor layer of
the fiber layer (114) to form a precursor layer of the resin layer (115);
applying pressure of proper magnitude on the outer periphery of the precursor
15 layer of the resin layer (115) to form a convex part (114c) on the inner
periphery of the precursor layer of the fiber layer (114); removing the
precursor layers of the fiber layer (114) and the resin layer (115) from the
male component (102) by rotating them in a circumferential direction of the
male component (102); cutting the precursor layers of the fiber layer (114)
20 and the resin layer (115) into doughnut-shaped pieces to make the fiber layer
(114) and the resin layer (115) from each piece; and adhering the cover
member (116) to the fiber layer (114) and the resin layer (115) with adhesive.
Obviously, if no cover member is needed, the cover member adhering step is
omitted.
25
[0089] (Features of ball screw of second embodiment)
According to the above construction, by virtue of making the fiber
layer (114), which is fitted with the male grooves (107) of the male
component (102), of woven fabric impregnated with rubber or the like, there
30 can be simultaneously accomplished the reduction of the entry of fine foreign
substances between the male and female components (102, 103) as well as the
reduction of the sliding resistance therebetween when shifting them in a
relative manner in an axial direction, both of which reductions as two
problems are trade-off related to each other. Further, the fiber layer (114)
35 impregnated with rubber or the like can improve the resistance to wear on the
surface of the fiber layer (114) caused by friction generated between the fiber
layer (114) and the male component (102). Still further, by laminating the
resin layer (115) for reinforcing the fiber layer (114) on the surface (114d)
opposite to the surface (114b) on which a hole (114a) is formed with respect
40 to the fiber layer (114), the fiber layer (114) and the resin layer (115) can be
stably fixed to the female component (103) at both ends thereof through the
use of the cover member (16). Still further, by rendering the length of the
inner periphery (114b) of the seal member (104) in the axial direction as being
shorter than or equal to the pitch width of the plurality of male grooves of the
27
male component (102), one can render the seal member (104) as being less
rigid so as to exhibit full flexibility, thereby promoting the inner periphery
(114b) to follow the surface of the male component (102). As a result, by
virtue of the ball screw (101), one can improve sealing property by closing a
gap between the seal member (104) and the male component 5 (102) even when
causing the ball screw (101) to work.
[0090] Specific constructions according to the present invention are not
limited to the second embodiment described above with reference to the
10 drawings. The scope of the present invention is not encompassed by the
above explanations of the embodiment but particularly pointed out by the
claims, and the equivalents of the claim recitations as well as all the
modifications within the scope of the claims fall within the scope of the
present invention.
15
[0091] For example, in the second embodiment, there is described an
example of arranging a pair of seal members (104) at both ends of the female
component (103), respectively, in the axial direction; however, the present
invention shall not be limited to such an example, and a seal member (104)
20 may be arranged at any one of the two ends of the female component (103) in
the axial direction, in accordance with the usage circumstances.
[0092] The second embodiment shows an example of male grooves (107) of
a male component (102) having four thread screw structure, but the present
25 invention shall not be limited to the example, and the number of threads of the
male grooves (107) may be changed in accordance with the usage
circumstances of the ball screw (101).
[0093] In the second embodiment, there is described an example of
30 impregnating fibers of the fiber layer (114) with rubber or the like; however,
the present invention shall not be limited to such an example, and the fibers
are required to be those which can be impregnated with rubber or the like and
which have low sliding resistance against the metal surface, and sheet-like
fabric made of fibers may be used for the fiber layer (114). For example,
35 canvas, velvet, denim, woven fabric, knitted fabric impregnated with rubber or
the like may be used. Horizontally and/or vertically stretchy fibers may also
be used.
[0094] Further, in the second embodiment, one seal member is arranged at
40 each of the both ends in the axial direction of the female component of the
ball screw; however, this may be modified in such a manner that e.g. a
plurality of seal members may be arranged coaxially in series in a continuous
manner at one end or both ends of the female component, and still further, a
gap may be made between the seal members. As a result, the plurality of
28
seal members can achieve lower in rigidity than a single-piece seal member
having the same fitting surface in length in the axial direction as the
construction, and therefore the slidability of the fitting surface is improved in
comparison with that of the single-piece seal member. Still further, the seal
members in the modified example are more flexible than 5 the single-piece seal
member, and therefore the fitting surface of the seal members is promoted to
follow the surface of the male component in comparison with the single-piece
seal member. Still further, according to the plurality of seal members
arranged coaxially in series, the edges of the respective seal members (on the
10 side contacting the male component) are configured such that dust and the like
can be scraped off the surface of the male component. In other words, the
seal members can reduce the entry of dust and the like into the ball screw to a
greater degree than the single-piece seal member does.
15 [0095] (Third Embodiment)
Hereinafter, the ball screw in the first embodiment of the present
invention will be described with reference to FIGS. 11-15. Regarding a pair
of seal members (204) shown in FIG. 12 not necessarily needed to be
explained separately, it is to be noted that each of the parts is provided with a
20 reference numeral with respect to one seal member (204) (on the left), while
reference numerals are appropriately omitted for some parts with respect to
the other seal member (204) (on the right), for the sake of simplification.
[0096] The ball screw (201), as shown in FIGS. 11 and 12, includes a male
25 component (202), a female component (203), and a pair of seal members
(204).
[0097] The male component (202) is metallic and, as shown in FIG. 13, has a
rod-shaped main body part (205) and a plurality of male grooves (207) formed
30 in a spiral manner on the outer periphery (206) of the main body part (205).
[0098] The female component (203) is metallic and, as shown in FIG. 14, has
a cylindrical part (208) in a cylindrical shape, and a platy part (209) in a platy
shape formed on an end of the cylindrical part (208). The cylindrical part
35 (208) and the platy part (209) are integrally molded. As shown in FIG. 12, a
plurality of female grooves (212) are formed on the inner peripheries (210,
211) of the cylindrical part (208) and the platy part (209). Each female
groove (212) is spirally formed in a similar manner to each male groove (207),
and formed at a position where the female groove (212) faces the male groove
40 (207) of the male component (202) as shown in FIG. 12. Further, as shown
in FIG. 12, circulation paths (213), through which a plurality of balls B2 can
circulate, are formed inside the cylindrical part (208), and paths P2 capable of
communicating with the circulation paths (213) are formed between the male
grooves (207) and the female grooves (212). The paths P2 are filled with the
29
plurality of balls B2.
[0099] The ball screw (201) in this embodiment is configured as an endless
circulation path such that the relative rotation of the male and female
components (202, 203) allows the balls B2 to roll 5 through the paths P2 and
thereafter return to an original position through the circulation paths (213).
Such circulation of the balls B2 is performed in a repetitive manner, which
enables the male and female components (202, 203) to shift in a relative
manner in an axial direction while being fitted together. The male grooves
10 (207) in this embodiment are formed in a four thread screw structure. In
other words, the number of threads with respect to the grooves is four, and
therefore four circulation paths (213) are formed accordingly.
[0100] As shown in FIG. 12, each of the seal members (204) includes a fiber
15 layer (214), a rubber layer or resin layer (first rubber layer or resin layer)
(215), a cover member (216), and a rubber layer or resin layer (second rubber
layer or resin layer) (217). Hereinafter, it is to be noted that the first rubber
layer or resin layer (215) will be referred to as “resin layer (215)” in an
abbreviated manner, and that the second rubber or resin layer (217) will be
20 referred to as “resin layer (217)” in an abbreviated manner.
[0101] The fiber layer (214) may be made of, e.g., aramid fiber, nylon,
urethane, cotton, silk, linen, acetate, rayon, fluorine-containing fiber, polyester,
or the like, which are impregnated with rubber or resin. The fiber layer (214)
25 may be made of e.g. short fibers and long fibers.
[0102] By virtue of impregnating fibers with rubber or resin, rubber material
or resin material is enabled to penetrate into the gaps within the fibers, and to
serve as fiber layer (214) so as to bond these fibers. Further, by virtue of
30 impregnating fibers with rubber and the like, the wear caused by friction
between the fibers can be reduced, and still further, the resistance to wear on
the fiber layer (214) caused by friction between the fiber layer (214) and male
component (202) can be improved.
35 [0103] The rubber is required to be that with which the fibers can be
impregnated. As such types of rubber, the followings may be used in a neat
form or in a form denatured in various ways: e.g., urethane rubber, nitrile
rubber, silicon rubber, fluororubber, acrylic rubber, ethylene-propylene rubber,
butyl rubber, isoprene rubber, chlorinated polyethylene rubber,
40 epichlorohydrin rubber, hydrogenated nitrile rubber, chloroprene rubber,
polybutadiene rubber, styrene-butadiene rubber, natural rubber, and the like.
Each of these types of rubber may be used alone, or a plurality of types of
rubber selected therefrom may be used in a blended form. Further, the
rubber may contain appropriate amounts of traditional compounding
30
ingredients for rubber, such as vulcanizing agent, vulcanizing accelerator,
antioxidant, softener, plasticizer, filler, colorant, and the like as well as solid
lubricants such as graphite, silicone oil, fluorine powder, molybdenum
disulfide, or the like for enhancing the lubricity of the fiber layer (214). Still
further, the above types of rubber may be replaced 5 by or combined with
thermoplastic or thermosetting resin such as acrylic resin, polyester resin,
urethane resin, vinyl chloride resin, polypropylene, polycarbonate,
polyethylene terephthalate resin, fluorine resin, polyethylene,
acrylonitrile-styrene resin, acrylonitrile-butadiene-styrene resin, polystyrene
10 resin, polyvinyl chloride, polyvinylidene chloride, polyvinyl acetate, nylon,
alkyd resin, phenolic resin, epoxy resin, polyphenylene sulfide resin, and the
like.
[0104] When impregnating fibers with rubber or resin as described above, it
15 is preferable that the rubber or resin be dissolved by a solvent or another
means into a liquid state before dipping the predetermined fibers (short fibers,
long fibers, fabric) in the liquid. The sheet-like fabric made of the fibers
may be used as a precursor of the fiber layer (214). This fabric is
impregnated with rubber or resin in the same way as mentioned above.
20
[0105] The fabric may be, e.g., non-woven fabric made of irregularly tangled
fibers, regularly-formed woven, knitted fabric, or the like. These fabrics are
characterized by facilitating impregnation (easier handling) with rubber and
the like, and further facilitating adhesion to the surface of the cover member
25 (216) in comparison with those made of fibers (short or long fibers) only,
because these fabrics are in sheet form. The woven fabric may be made in a
plain weave, satin weave, twill weave, or the like.
[0106] The fabric may preferably be stretchy to some extent. By virtue of
30 such stretchiness, when the fabric is formed so as to be in line with the male
grooves (207) in shape, there can be achieved the advantageous effects that:
the surface of the fabric can easily be shaped in accordance with the form of
the male grooves (207); and the fiber layer (214) has the surface subjected to
few creases and uniformly finished, thereby enabling smooth fitting between
35 the male component (202) and the seal members (204), and further enabling
decrease in sliding resistance therebetween. By producing the fiber layer
(214) of the fabric in such a manner that a stretchiness direction of the fabric
in particular can coincide with at least a height direction (an axial direction of
the ball screw) of the cylindrically-shaped fiber layer (214), it becomes
40 possible that the surface of the fiber layer (214) is subjected to fewer creases.
[0107] As shown in FIG. 12, the fiber layer (214) has an inner periphery
(inner surface of the fiber layer (214)) (214b), and such an inner periphery
(214) has a convex part (214c) formed thereon and shaped in accordance with
31
the form of the male grooves (207) of the male component (202). The
convex part (214c) has a resin layer (217) (at least 50 μm thick) laminated on
a surface thereof, and such a resin layer (217) is formed through steps that will
be described later. This resin layer (217) is cured substance, but has some
flexibility. Lamination is defined as application of 5 resin or the like having
relatively high viscosity, e.g. 1000 cps or above, to a material surface. As
shown in FIG. 12, the fiber layer (214) has the inner periphery (214b) placed
at the position surrounding the resin layer (217), and has the convex part
(214c) formed on the inner periphery (214b). The convex part (214c) is a
10 part capable of being fitted in the male grooves (207) of the male component
(202) through the resin layer (217) when the male component is inserted into
the inner periphery (214b).
[0108] The resin layer (217) has water or oil repellency. In order to express
15 the function of water and/or oil repellency, the resin layer (217) may be made
of rubber or resin containing at least one out of a group consisting of silicone
resin, polytetrafluoroethylene, urethane resin, acrylic silicone resin, and fine
particles thereof, or alternatively, the resin layer (217) may be made of
silicone resin, polytetrafluoroethylene, urethane resin, or acrylic silicone resin
20 in a neat form. Nitrile-butadiene rubber may be an example for the rubber or
resin containing at least one out of silicone resin, polytetrafluoroethylene,
urethane resin, acrylic silicone resin, and fine particles thereof. As a guide,
the amount of the resin added in the rubber or resin to express the function of
water and/or oil repellency is 5 wt% or more and less than 50 wt%, preferably
25 10 wt% or more and less than 30 wt%, with respect to 100 as the total amount
of the rubber or resin. If the ingredient to express the function of water or oil
repellency is too little in amount, the resin layer (217) does not effectively
repel water or oil. On the other hand, if the ingredient is too large in amount,
the resin layer (217) does not effectively adhere to the fiber layer (214) and is
30 peels off from the fiber layer (214) during operations. The resin layer (217)
having a predetermined thickness (at least 50 μm) is laminated on the inner
periphery (214b) of the fiber layer (214) in accordance with the shape of the
inner periphery (214b). Still further, the resin layer (217), as shown in FIG.
15, is a cylindrically-shaped thin layer having a hole (217a) defined therein.
35 As shown in FIG. 12, the hole (217a) is configured such that it communicates
with the inner peripheries (210, 211) of the female component (203). Still
further, the resin layer (217) includes an inner periphery (inner surface of
resin layer (217)) (217b) arranged at a position where it surrounds the hole
(217a), and a convex part (217c) formed on the inner periphery (217b). The
40 convex part (217c) is arranged on a region such that, when inserting the male
component (202) into the hole (217a), the convex part (217c) can be fitted in
the male grooves (207) of the male component (202) inserted into the hole
(217a).
32
[0109] As the resin layer (215), e.g. urethane rubber, nitrile rubber, silicon
rubber, fluororubber, acrylic rubber, ethylene-propylene rubber, butyl rubber,
isoprene rubber, chlorinated polyethylene rubber, epichlorohydrin rubber,
hydrogenated nitrile rubber, chloroprene rubber, polybutadiene rubber,
styrene-butadiene rubber, natural rubber, and the 5 like may be used in a neat
form or in a form denatured in various ways, or alternatively, acrylic resin,
polyester resin, urethane resin, vinyl chloride resin, polypropylene,
polycarbonate, polyethylene terephthalate resin, fluorine resin, and the like
may be used.
10
[0110] The resin layer (215) is a cylindrically-shaped layer having a hole
defined therein, and the outer peripheral portion of the fiber layer (214) can be
inserted into such a hole. As shown in FIG. 12, the resin layer (215) is
laminated on a surface (214d) on a side opposite to an inner-periphery
15 (214b)-formed side with respect to the fiber layer (214), where the
inner-periphery (214b)-formed side is indicative of a side of the fiber layer
(214) at which the inner periphery (214b) is formed.
[0111] A back-up ring may be installed on the outer peripheral portion of the
20 resin layer (215) so as to apply inward pressure to the inner periphery (214b)
of the fiber layer, thereby enabling improvements in the sealing property.
The back-up ring, such as O-ring, garter spring, and the like, is configured to
be capable of applying inward pressure to the inner periphery (214b) of the
fiber layer, and it is preferable to select a type of back-up ring capable of
25 generating inward pressure of proper magnitude optimized with respect to a
balance between the sealing property and the slidability.
[0112] The cover member (216) is made of e.g. plastic or metal and, as
shown in FIG. 15, includes a cylindrical part (216a), a ring part (216b), and a
30 ring-shaped installation part (216c), all of which are integrally molded
[0113] Further, the cover member (216) may be adhered to the fiber layer
(214) or the resin layer (215) with adhesives: e.g. acrylic resin adhesive,
olefin adhesive, urethane resin adhesive, ethylene-vinyl acetate resin adhesive,
35 epoxy resin adhesive, vinyl chloride resin adhesive, chloroprene rubber
adhesive, cyanoacrylate adhesive, silicon adhesive, styrene-butadiene rubber
adhesive, nitrile rubber adhesive, hot-melt adhesive, phenolic resin adhesive,
melamine resin adhesive, urea resin adhesive, resorcinol adhesive, or the like.
There are methods to cure an adhesive for bonding: by heating an adhesive so
40 as to cause the adhesive to melt as fluid, applying the melting adhesive, and
thereafter cooling the applied adhesive; just by heating an adhesive; or the like.
As possible surfaces to be bonded, e.g., contacting surfaces of the cylindrical
part (216a) and the resin layer (215) of the cover member, contacting surfaces
33
of the ring part (216b) and the resin layer (215) of the cover member, or the
like may be considered.
[0114] As shown in FIG. 12, the cylindrical part (216a) is placed on the
surface (215b) on a side opposite to the surface 5 (215a) at a fiber-layer
(214)-formed side with respect to the resin layer (215), where the fiber-layer
(214)-formed side is indicative of a side of the resin layer (215) at which the
fiber layer (214) is formed. As shown in FIG. 12, the ring part (216b) is
placed at one end of the cylindrical part (216a), and is configured such that
10 surfaces (214f, 215d) on a side opposite to the surfaces (214e, 215c) at a
female-component (203)-formed side with respect to the fiber layer (214) and
the resin layer (215), respectively, are covered by the ring part (216b), where
the female-component (203)-formed side is indicative of a side of the fiber
layer (214) and the resin layer (215) at which the female component (3) is
15 formed
[0115] As shown in FIG. 12, the installation part (216c) is placed at the other
end of the cylindrical part (216a). The installation part (216c) is configured
such that the fiber layer (214) and the resin layer (215) covered by the
20 cylindrical part (216a) and the ring part (216b) can be installed by use of
fastening components (not shown) at each of both ends of the female
component (203) in an axial direction.
[0116] The cover member (216) shall not be limited to the above form but
25 may be configured in other forms as long as such forms allow the installation
thereof at an end of the female component (203) in an axial direction. As
such other forms, e.g., the fiber layer (214) and the resin layer (215) can be
installed by use of fastening components (not shown) at one end or each of
both ends of the female component (203) in the axial direction in such a
30 manner that these layers are fitted in a bore formed at one end or each of both
ends of the female component (203) in the axial direction before a platy cover
member having a hole for allowing the male component (202) to pass
therethrough is adhered to a side surface of the resin layer (215).
35 [0117] If the fiber layer (214) and the resin layer (215) are fitted in the bore
formed at one end or each of both ends of the female component (203) in the
axial direction as mentioned above and thereafter fixation screws (not shown)
are drive-fitted from the cylindrical part (208) or the outer peripheral portion
of the platy part (209) of the female component (203) to the resin layer (215),
40 there are cases where the cover member (216) may not be needed.
[0118] The seal members (204) may be manufactured by performing
successively the steps of, in one example: bonding or coating one surface of
sheet-like woven fabric impregnated with rubber or the like with resin having
34
relatively high viscosity (resin of water and/or oil repellency after cured) and
thereafter curing the sheet-like woven fabric having the one surface bonded or
coated with the resin, and wrapping the cured sheet-like woven fabric around
the outer periphery (206) of the male component (202) to form a precursor
layer of the resin layer (217) and the fiber layer (214); 5 wrapping a sheet of
resin around the outer periphery of the precursor layer of the fiber layer (214)
to form a precursor layer of the resin layer (215); applying pressure of proper
magnitude on the outer periphery of the precursor layer of the resin layer
(215) to form a convex part (214c) on the inner periphery of the precursor
10 layer of the fiber layer (214); removing the precursor layers of the fiber layer
(214) and the resin layer (215) from the male component (202) by rotating
them in a circumferential direction of the male component (202); cutting the
precursor layers of the fiber layer (214) and the resin layer (215) into
doughnut-shaped pieces to make the fiber layer (214) and the resin layer (215)
15 from each piece; and adhering the cover member (216) to the fiber layer (214)
and the resin layer (215) with adhesive. Obviously, if no cover member is
needed, the cover member adhering step is omitted.
[0119] (Features of ball screw of third embodiment)
20 According to the above construction, by virtue of making the fiber
layer (214), which is fitted with the male grooves (207) of the male
component (202), of woven fabric impregnated with rubber or the like, there
can be simultaneously accomplished the reduction of the entry of fine foreign
substances between the male and female components (202, 203) as well as the
25 reduction of the sliding resistance therebetween when shifting them in a
relative manner in an axial direction, both of which reductions as two
problems are trade-off related to each other. Further, the fiber layer (214)
impregnated with rubber or the like can improve the resistance to wear on the
surface of the fiber layer (214) caused by friction generated between the fiber
30 layer (214) and the male component (202). Still further, by laminating the
resin layer (215) for reinforcing the fiber layer (214) on the surface (214d)
opposite to the surface (214b) on which a hole (214a) is formed with respect
to the fiber layer (214), the fiber layer (214) and the resin layer (215) can be
stably fixed to the female component (203) at both ends thereof through the
35 use of the cover member (216). Further, by virtue of forming the rubber or
resin layer (217) of water or oil repellency, the entry of dust, grease, oil, and
the like into the fiber layer (214) can be prevented, and therefore the
degradation of the fiber layer (214) can be reduced. Still further, since the
surface friction coefficient of the resin layer (217) is lower than the previous
40 one, it is unlikely that the sliding wear between the male component (202) and
the seal members (204) is generated, thereby improving the durability of the
seal members (204), i.e., increasing the life of the seal members (204), and
eventually increasing the life of the ball screw (201).
35
[0120] Specific constructions according to the present invention are not
limited to embodiments described above with reference to the drawings. The
scope of the present invention is not encompassed by the above explanations
of embodiments but particularly pointed out by the claims, and the equivalents
of the claim recitations as well as all the modifications 5 within the scope of the
claims fall within the scope of the present invention.
[0121] For example, in embodiments, there is described an example of
arranging a pair of seal members (204) at both ends of the female component
10 (203), respectively, in the axial direction; however, the present invention shall
not be limited to such an example, and a seal member (204) may be arranged
at any one of the two ends of the female component (203) in the axial
direction, in accordance with the usage circumstances.
15 [0122] Embodiments show an example of male grooves (207) of a male
component (202) having four thread screw structure, but the present invention
shall not be limited to the example, and the number of threads of the male
grooves (207) may be changed in accordance with the usage circumstances of
the ball screw (201).
20
[0123] In embodiments, there is described an example of impregnating fibers
of the fiber layer (214) with rubber or the like; however, the present invention
shall not be limited to such an example, and sheet-like fabric made of fibers
may be used for the fiber layer (214). For example, canvas, velvet, denim,
25 woven fabric, knitted fabric impregnated with rubber or the like may be used.
Horizontally and/or vertically stretchy fibers may also be used.
[0124] (Reference Numerals)
1, 101, 201 Ball screw
30 2, 102, 202 Male component
3, 103, 203 Female component
4, 104, 204 Seal member
5, 105, 205 Main body part
6, 106, 206 Outer periphery
35 7, 107, 207 Male groove
8, 108, 208 Cylindrical part
9, 109, 209 Platy part
10, 11, 110, 111, 210, 211 Inner periphery
12, 112, 212 Female groove
40 13, 113, 213 Circulation path
14, 114, 214 Fiber layer
14a, 114a, 214a Hole
14b, 114b, 214b Inner periphery (fitting surface)
14c, 114c, 214c Convex part
36
14d-14f, 15a-15d, 114d-114f, 115a-115d, 214d-214f, 215a-215d Surface
15, 115, 215, 217 Resin layer (rubber layer)
16, 116, 216 Cover member
16a, 116a, 216a Cylindrical part
16b, 5 116b, 216b Ring part
16c, 116c, 216c Installation part
217b Inner periphery (inner surface of the resin
layer 217)
B, B1, B2 Ball
10 P, P1, P2 Circulation path
37
We Claim:
1. A ball screw comprising:
a male component having a plurality of male grooves formed on an
outer periphery thereof such that a ball is allowed to 5 roll in the plurality of
male grooves;
a female component having a plurality of female grooves facing the
plurality of male grooves formed on an inner periphery thereof such that the
ball is allowed to roll in the plurality of female grooves, and having a
10 circulation path formed therein such that the ball is allowed to circulate
through the circulation path; and
a seal member arranged at one end, at the other end, or at each of one
and the other ends of the female component in an axial direction, wherein
the male and female components are fitted together in the axial
15 direction, and wherein
the seal member includes
a hole capable of communicating with the inner periphery of the
female component,
a fiber layer having a fitting surface formed with a convex part
20 capable of being fitted in the plurality of male grooves of the male component
when the male component is inserted into the hole, the fitting surface having
at least a surface made of fibers impregnated with rubber or resin, and
a rubber or resin layer laminated on a surface opposite to the fitting
surface of the fiber layer.
25
2. A ball screw comprising:
a male component having a plurality of male grooves formed on an
outer periphery thereof such that a ball is allowed to roll in the plurality of
male grooves;
30 a female component having a plurality of female grooves facing the
plurality of male grooves formed on an inner periphery thereof such that the
ball is allowed to roll in the plurality of female grooves, and having a
circulation path formed therein such that the ball is allowed to circulate
through the circulation path; and
35 a seal member arranged at one end, at the other end, or at each of one
and the other ends of the female component in an axial direction, wherein
the male and female components are fitted together in the axial
direction, wherein
the seal member includes
40 a hole capable of communicating with the inner periphery of the
female component,
a fiber layer having a fitting surface formed with a convex part
capable of being fitted in the plurality of male grooves of the male component
when the male component is inserted into the hole, the fitting surface having
38
at least a surface made of fibers impregnated with rubber or resin, and
a rubber or resin layer laminated on a surface opposite to the fitting
surface of the fiber layer, and wherein
a length of the fitting surface in the axial direction is shorter than or
equal to a pitch width of the plurality of male grooves 5 of the male component.
3. The ball screw according to claim 2 wherein, at said one end, at said
the other end, or at said each of one and the other ends of the female
component in the axial direction, a plurality of seal members, as the seal
10 member, are arranged coaxially in series in a continuous manner.
4. A ball screw comprising:
a male component having a plurality of male grooves formed on an
outer periphery thereof such that a ball is allowed to roll in the plurality of
15 male grooves;
a female component having a plurality of female grooves facing the
plurality of male grooves formed on an inner periphery thereof such that the
ball is allowed to roll in the plurality of female grooves, and having a
circulation path formed therein such that the ball is allowed to circulate
20 through the circulation path; and
a seal member arranged at one end, at the other end, or at each of one
and the other ends of the female component in an axial direction, wherein
the male and female components are fitted together in the axial
direction, and wherein
25 the seal member includes
a hole capable of communicating with the inner periphery of the
female component,
a fiber layer configured such that the fiber layer can be fitted with the
plurality of male grooves of the male component when the male component is
30 inserted into the hole, the fiber layer having at least one surface made of fibers
impregnated with rubber or resin,
a first rubber or resin layer laminated on a surface opposite to the at
least one surface of the fiber layer, and
a second rubber or resin layer of water and/or oil repellency
35 laminated with a predetermined thickness on the at least one surface of the
fiber layer.
5. A seal member used for a ball screw characterized in that
a male component of the ball screw having a plurality of male
40 grooves formed on an outer periphery thereof such that a ball is allowed to roll
in the plurality of male grooves, and
a female component of the ball screw having a plurality of female
grooves facing the plurality of male grooves formed on an inner periphery
thereof such that the ball is allowed to roll in the plurality of female grooves,
39
and having a circulation path formed therein such that the ball is allowed to
circulate through the circulation path,
are fitted together in an axial direction, and that
the seal member comprises:
a hole capable of communicating with the 5 inner periphery of the
female component;
a fiber layer having a fitting surface formed with a convex part
capable of being fitted in the plurality of male grooves of the male component
when the male component is inserted into the hole, the fitting surface having
10 at least a surface made of fibers impregnated with rubber or resin; and
a rubber or resin layer laminated on a surface opposite to the fitting
surface of the fiber layer.
6. A seal member used for a ball screw characterized in that
15 a male component of the ball screw having a plurality of male
grooves formed on an outer periphery thereof such that a ball is allowed to roll
in the plurality of male grooves, and
a female component of the ball screw having a plurality of female
grooves facing the plurality of male grooves formed on an inner periphery
20 thereof such that the ball is allowed to roll in the plurality of female grooves,
and having a circulation path formed therein such that the ball is allowed to
circulate through the circulation path,
are fitted together in an axial direction, and that
the seal member comprises:
25 a hole capable of communicating with the inner periphery of the
female component;
a fiber layer having a fitting surface formed with a convex part
capable of being fitted in the plurality of male grooves of the male component
when the male component is inserted into the hole, the fitting surface having
30 at least a surface made of fibers impregnated with rubber or resin; and
a rubber or resin layer laminated on a surface opposite to the fitting
surface of the fiber layer, and that
a length of the fitting surface in the axial direction is shorter than or
equal to a pitch width of the plurality of male grooves of the male component.
35
7. The seal member according to claim 6 wherein a plurality of seal
members, as the seal member, are arranged coaxially in series in a continuous
manner.
40 8. A seal member used for a ball screw characterized in that
a male component of the ball screw having a plurality of male
grooves formed on an outer periphery thereof such that a ball is allowed to roll
in the plurality of male grooves, and
a female component of the ball screw having a plurality of female
40
grooves facing the plurality of male grooves formed on an inner periphery
thereof such that the ball is allowed to roll in the plurality of female grooves,
and having a circulation path formed therein such that the ball is allowed to
circulate through the circulation path,
are fitted together in an axial 5 direction, and that
the seal member comprises:
a hole capable of communicating with the inner periphery of the
female component;
a fiber layer configured such that the fiber layer can be fitted with the
10 plurality of male grooves of the male component when the male component is
inserted into the hole, the fiber layer having at least one surface made of fibers
impregnated with rubber or resin;
a first rubber or resin layer laminated on a surface opposite to the at
least one surface of the fiber layer; and
15 a second rubber or resin layer of water and/or oil repellency
laminated with a predetermined thickness on the at least one surface of the
fiber layer.
9. A seal structure applied to a ball screw characterized in that
20 a male component of the ball screw having a plurality of male
grooves formed on an outer periphery thereof such that a ball is allowed to roll
in the plurality of male grooves, and
a female component of the ball screw having a plurality of female
grooves facing the plurality of male grooves formed on an inner periphery
25 thereof such that the ball is allowed to roll in the plurality of female grooves,
and having a circulation path formed therein such that the ball is allowed to
circulate through the circulation path,
are fitted together in an axial direction, and that
the seal structure comprises:
30 a hole capable of communicating with the inner periphery of the
female component; and
a fiber layer having a fitting surface formed with a convex part
capable of being fitted in the plurality of male grooves of the male component
when the male component is inserted into the hole, the fitting surface having
35 at least a surface made of fibers impregnated with rubber or resin.
10. A seal structure applied to a ball screw characterized in that
a male component of the ball screw having a plurality of male
grooves formed on an outer periphery thereof such that a ball is allowed to roll
40 in the plurality of male grooves, and
a female component of the ball screw having a plurality of female
grooves facing the plurality of male grooves formed on an inner periphery
thereof such that the ball is allowed to roll in the plurality of female grooves,
and having a circulation path formed therein such that the ball is allowed to
41
circulate through the circulation path,
are fitted together in an axial direction, and that
the seal structure comprises:
a hole capable of communicating with the inner periphery of the
5 female component; and
a fiber layer having a fitting surface formed with a convex part
capable of being fitted in the plurality of male grooves of the male component
when the male component is inserted into the hole, the fitting surface having
at least a surface made of fibers impregnated with rubber or resin, and that
10 a length of the fitting surface in the axial direction is shorter than or
equal to a pitch width of the plurality of male grooves of the male component.
11. The seal structure according to claim 10 wherein a plurality of seal
structures, as the seal structure, are configured coaxially in series in a
15 repetitive manner.
12. A seal structure applied to a ball screw characterized in that
a male component of the ball screw having a plurality of male
grooves formed on an outer periphery thereof such that a ball is allowed to roll
20 in the plurality of male grooves, and
a female component of the ball screw having a plurality of female
grooves facing the plurality of male grooves formed on an inner periphery
thereof such that the ball is allowed to roll in the plurality of female grooves,
and having a circulation path formed therein such that the ball is allowed to
25 circulate through the circulation path,
are fitted together in an axial direction, and that
the seal structure comprises:
a hole capable of communicating with the inner periphery of the
female component;
30 a fiber layer configured such that the fiber layer can be fitted with the
plurality of male grooves of the male component when the male component is
inserted into the hole, the fiber layer having at least one surface made of fibers
impregnated with rubber or resin; and
a rubber or resin layer of water and/or oil repellency laminated with a
35 predetermined thickness on the at least one surface of the fiber layer.