Technical field
This invention relates to a method of making a brush and a brush obtained in this way.
The invention applies to the field of industrial and/or hobby brushes, that is to say, brushes
used for machining processes (for example, deburring of surfaces, cleaning of welds, etc.)
which can be used both in industrial and private contexts.
Background Art
In the process for making brushes according to the prior art, the elements making up the brush
are generally assembled using the threaded reduction device.
These components are, for the circular brushes, flanges, ring with wires and reduction device,
and for the cup-shaped brushes, inner cup, ring with wires, outer cup and reduction device.
In the prior art methods, firstly the circular part of the reduction device is passed through the
central hole present in the parts used for forming the brush, which are all obtained by cold
moulding.
Secondly, there is a step for drawing an edge of the extension of the reduction device
protruding beyond the elements which form the brush, whilst the other end of the reduction
device has a larger dimension to prevent the escape of the elements.
The drawing produces a tab of the reduction device folded to secure together all the elements
of the brush body (pressing them against the part of the reduction device with larger
dimensions).
There is also, for the cup-shaped brushes, a retaining ring associated with an end portion of the
outer cup and positioned outside the first portion of the of the wires for clamping them, exerting
a pressure on them towards the inside of the brush, that is, towards the longitudinal axis (which
also constitutes the axis of rotation of the brush when this is associated with a spindle).
This retaining ring is currently used, in the cup-shaped brushes, to have a better use of the
metal wires.
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It should be noted that the industrial brushes also differ according to the semi-worked element
used, in which the wires are locked, and the material making the wires which must perform the
brushing action.
With regard to the method of anchoring the wires to the flange, the semi-worked elements
include twisted bundle rings and crimped or straight wire rings.
In the twisted bundle rings, the wires are grouped together in bundles, and screwed there by
twisting; each bundle is associated with a hole formed by the flange close to its outer
circumference.
In the crimped wire rings, the flange, which is called the ring nut, forms on a relative outer
lateral edge a groove, in which the first portion (that is, the first end) of the wires is inserted.
The ring nut acts in conjunction with a supporting ring, about which the wires are then bent in a
"U" shape, to keep the wires in the desired position.
The ring nut is also flanged to keep tight the wires bent and distributed along the entire
circumference of the inner supporting ring (made of metal).
With regard to the material making up the wires, the brushes include metal wire brushes, plastic
wire brushes, mixed metal-plastic wire brushes and natural wire brushes.
In this regard, it should be noted that the twisted bundle brushes always have metal wires. In
other words, the twisted bundles configuration is not used for natural or plastic wire brushes.
For this reason, the configuration with crimped or straight wire rings is always used for natural
or plastic wire brushes.
The brushes must, for their use, be robust, in such a way as to work at particularly high speeds
of rotation without breaking or deforming (in general, the mechanical parts from which they are
made break or deform or the wires detach).
Another problem linked to the high speeds of rotation at which the brushes must operate
consists in their stability and equilibrium.
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The brush must always rotate as a rigid body about its longitudinal axis, which must remain
stationary and without any movement from the axis of rotation during the working.
In addition, these must be the characteristics of all the types of brushes, therefore regardless of
the materials with which the wires are made or the arrangement of the wires themselves or the
system for production of the brushes and the elements used for their assembly (with metal
elements obtained by cold moulding or with assembly of the various components with plastic
materials).
The prior art deals with these problems by perfecting the finish and the assembly of all the
elements which make up the brushes.
However, this results in an increase in the costs of the brushes, due to the number and the
complexity of the components and their assembly.
In light of this, another drawback is associated with the fact of having numerous elements which
make up the brush so that the brush production firms must hold a large supply of components
in store (with a consequent waste of money, resources and space).
A further drawback of the prior art solutions, in terms of robustness and stability of the brush,
consists in the machining tolerances of the components, especially of the reduction device and
the parts which must be mounted with it for formation of the brush.
Another problem of the prior art solutions is linked to the fact that the brushes, made (for
reasons of robustness) with components made of steel, must have increasingly large
thicknesses with consequent increases in the costs and the problems in their production by cold
moulding.
Lastly, the brushes comprising parts made of iron or plastic cannot be used safely for
machining special metal surfaces (for example stainless steel), or in hazardous work
environments which require explosion-proof safety measures, as there is the risk of producing
sparks or electrostatic charges between the various components of the brush which in turn can
produce electrostatic charges in environments with dangerous atmospheres due to the
presence of gas.
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It should be noted that there are technical solutions which involve welding together the wires of
the brush with resins or adhesives, and then coupling a cap (that is, a cup) by pressure to the
outside of the ends of the welded wires; the cup being made of plastic material, that is, obtained
using special plastic resins or by embedding the wires or the rings with wires (semi-worked
elements) in plastic dies.
These plastic caps or cups have a problem linked to the high fragility of the material, so they
are only used with plastic wires in order to reduce the mechanical stresses.
This construction method cannot be used for the production of brushes with metal wires due to
the high stresses and the high temperatures which are developed during their use.
Moreover, these solutions do not resolve the above-mentioned drawbacks, for example with
regard to the possibility of using the brush in sterile environments, or with regard to the
robustness and the resistance during operation at high speeds or at high temperatures,
because the wires, which are welded and the outer plastic cup only acts as a covering element,
detach or break.
Other more recent solutions use systems for the production of brushes with moulding by
casting or by injection of the plastic material which, when solidifying, keep together all the
components of the brush.
This latter production system, in particular with brushes with metal wires, also has the following
main drawbacks:
- there are many unbalanced brushes since the positioning in the mould of the wires or of the
rings with wires is problematic;
- the effect of the heating due to the increase in temperatures (approx. 100°C) during the
machining of the brush makes the mechanical strength of the plastic die which assembles
the various elements of the brush critical.
This drawback makes the breakage of the metal wires and, therefore, the break up of the brush
easier, as the locking due to the plastic die quickly deteriorates with the increase in the
temperature:
- plastic cannot be used in the brushes with special metal elements (e.g. stainless steel or
non-sparking ) as it causes contamination of the surfaces or, as it is a plastic material, it can
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generate high differences in electrical potential between the various metal parts which make
up the brush with the risk of electrical discharges (sparks);
- different materials in the composition (plastic, steel, paints, etc) make the brush a very
costly object for recycling.
Disclosure of the invention
In this context, the technical purpose which forms the basis of this invention is to propose a
method for making a brush and a brush that overcome the above mentioned drawbacks of the
prior art.
More specifically, the aim of this invention is to provide a method of making a single brush, with
reduction of the production costs and ease of recycling the materials, whilst guaranteeing high
levels of robustness even when using with high rotation speeds and at high temperatures
(greater than 100°C).
Moreover, the aim of the invention is to provide a brush or brush element which is simple to
make and high in performance.
According to this invention, it is possible to make a brush in which auxiliary elements that can
make its use more functional can also be mounted mechanically (e.g. wire retaining ring,
ventilation elements or other device).
A further aim of the invention is to provide a brush which can be used safely for machining
metal surfaces (for example, made of stainless steel) or in environments which require total
explosion-proof safety measures and which can also be easily machined mechanically in cases
in which, for example, a greater degree of equilibrium is required.
Moreover, the aim of this invention is to provide a versatile method, by which it is also possible
to make elements with innovative geometrical shapes and which are used for traditional
brushes and therefore also produce brushes with synthetic or natural wires.
The technical purpose indicated and the aims specified are substantially achieved by a method
for method for making a brush and a brush or brush element, comprising the technical features
described in one or more of the appended claims.
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More specifically, the method according to this invention comprises at least the following steps:
- preparing a plurality of metal wires positioned in such a way as to form at least one bundle
having a predetermined width such as to occupy a predetermined space;
- preparing a portion of the metal wires inside a cavity of a mould having a predetermined
geometrical shape;
- feeding a molten metal inside the cavity of the mould until the cavity is filled;
- cooling the molten metal to allow the solidification with the portion of metal wires inside, so
as to form a single brush body from which the second portion, in use not embedded, of the
metal wires protrudes, designed to perform the brushing operation.
It should be noted that the molten metal comprises preferably aluminium or aluminium alloys
and that the set of wires is made of metal.
According to the invention, the method comprises a step for tempering the metal wires made by
the molten metal fed into the mould on the first portion of the wires and by the mould on the
second portion.
Advantageously, the wires are tempered by the embedding in the molten metal, also during its
cooling.
Preferably, the tempering of the second portion is achieved by forming in the mould a necking
which compresses the wires transversely to their direction of extension, in such a way as to
reduce the space occupied.
Thus, the method comprises preferably, between the preparing step and the feeding step, a
step for locking the metal wires inside the cavity transversely to a direction of extension of the
metal wires by at least one necking having a width less than the predetermined width of the
bundle in such a way as to compress the bundle causing a separation of the metal wires into a
first portion, embedded in use, and a second portion, in use not embedded. In this way the
necking maintains in contact with the wires so as to perform a tempering of the wires.
In the circular brushes, the metal wires extend in a radial direction starting from a central
annular body.
In this case, and in particular in the case of brushes with crimped wires, the mould has at least
one half-part equipped with an annular protrusion, concentric with the annular body and
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extending transversely to the wires for compressing them so as to form the necking and delimit
the radial extension of the brush body.
Preferably, the mould comprises two half-parts each equipped with a relative annular protrusion
opposite the annular protrusion of the other half-part for forming the necking; this also
considerably improves the holding of the molten aluminium inside the cavity which forms the
brush body.
On the other hand, to make a circular brush with twisted bundles, in which each bundle is
angularly spaced from the adjacent one, the mould comprises a central hollow portion, wherein
a first portion of the twisted bundles, in use embedded in the brush body, is positioned.
Starting from the central hollow portion, the mould comprises a plurality of radial ducts housing
the second portion, in use not embedded, of the twisted bundles, which keep in contact the
respective second portion for performing the tempering.
Preferably, also in this case the mould is defined by two superposable half-moulds, each
equipped with a central cavity and a plurality of radial grooves extending from the central cavity.
Each groove superposes a corresponding groove of the other half-mould to make the ducts
during the casting.
In the cup shaped brushes, the step of locking the metal wires comprises the following steps:
- positioning a disc-shaped body substantially concentric with an axis of rotation of the brush;
- positioning metal wires on the perimeter of the disc-shaped body;
- positioning an external annular body, in such a way as to define a circular crown for housing
the metal wires interposed between the discshaped body and the annular body so as to
form the necking.
Advantageously, the necking is obtained before inserting the semi-worked element (wires, discshaped
body and annular body) in the mould.
However, more preferably, in order to guarantee the tempering of the second portion of the
wires, the locking step also comprises the following sub-steps:
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- preparing a metal bushing made from a different material from the molten metal and from
the metal wires and having a diameter less than a diameter occupied by the second portion,
in use not embedded, of the metal wires;
- inserting the second portion of the metal wires in the bushing for further reducing the radial
extension of the metal wires.
It should be noted that the bushing has an axial extension greater than or equal to the second
portion of the metal wires, in use not embedded, in such a way as to remain in contact with it
during the feeding step so as to perform a complete tempering of the metal wires.
The bushing is not, however, part of the brush, so the method comprises a step for removing
the bushing after the cooling step.
The method allows a repeatability of the construction standard of the brush in a fast and precise
fashion with considerable reduction in the costs and with metals such as aluminium which
define characteristics of safety and lightness of the brush which cannot be achieved by
traditional brushes and with an improvement of the mechanical characteristics of the metal
wires.
Again, using the characteristics of metals such as aluminium alloys or similar alloys and using
semi-worked elements with wires made of brass, brushes are obtained which are fully
explosion-proof and also fully nonmagnetic for example using non-magnetic metal elements
(e.g. copper etc) for holding the wires made of brass.
Moreover, the locking of the wires performed by the solidification of the metal (aluminium) has a
mechanical strength greater than any type of coupling which is currently performed in the sector
of brushes.
It is important to note that the coupling between the metal wires and the molten material which
forms (once solidified) the brush body occurs immediately; the metal wires heat up (even before
the casting) immediately during the step of introduction and contact with the molten metal.
Moreover, this form of contact generates a metallic bond which is perfect and free of impurities
between the wire and the metal which, during its solidification, improves this locking by the
reduction of the space occupied by the ends of the metal wires.
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In addition, the method comprises a step for defining first constraint means on the brush body
designed to allow reversible connection with second constraint means complementary to them,
defined by an operational support or modular brush.
Preferably, the defining step comprises a step for making a threaded cavity inside the brush
body.
Still more preferably, the step for defining the first constraint means is performed at the same
time as the step for feeding molten metal into the cavity of the mould. More specifically, the
threading is obtained by inserting in the mould a core shaped in a complementary fashion to the
threading, in such a way that the metal solidifies with the correct shape.
Preferably, the core is coated with a layer of non-stick material to facilitate the removal.
Preferably, the following steps are comprised between the step for preparing a set of metal
wires and the step for feeding molten metal into relative zones defining passage channels for
the liquid metal:
- closing a movable part of the mould;
- locking at least the portion of metal wires inside the cavity of the mould.
In the preferred embodiment, the locking step is achieved by positioning an annular body (or
metal ring) and a disc-shaped body (or cup) concentric with each other in such a way as to form
an annular cross-section (or circular crown) for passing through and positioning the metal wires.
Thus, this step is achieved by positioning a disc-shaped body substantially concentric with an
axis of rotation of the brush, positioning metal wires perimetrally to the disc-shaped body and
positioning an external annular body, in such a way as to define a circular crown for housing the
metal wires interposed between the disc-shaped body and the annular body so as to lock the
metal wires.
In a further application, the method according to this invention comprises the following steps:
- making a first brush body having a predetermined geometrical shape equipped with at least
one substantially cylindrical central portion; the step being performed by feeding a molten
metal inside a cavity of a first mould having a predetermined geometrical shape;
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- making a second brush body having a predetermined geometrical shape complementary to
that of the first brush body; the step being performed by feeding a molten metal inside a
cavity of a second mould having a predetermined geometrical shape;
- preparing at least one ring equipped with a plurality of wires protruding radially to it;
- coupling the ring with the first brush body by inserting the ring in the substantially cylindrical
portion;
- coupling the second body with the first brush body by pressing;
Advantageously, by making the first and the second brush body by casting or injection
moulding (preferably using aluminium or an aluminium alloy) it is possible to make brushes
(cup-shaped or circular) with non-metallic wires (synthetic or natural) of the most diverse
shapes and with reduced production costs.
In effect, the forming by fusing allows fins for reinforcement or cooling of the brush surface to
be made, or holes for heat dispersal on the brush body in a simple and economical way.
This invention also relates to a brush or brush element for industrial or hobby purposes, made
preferably with the method described above.
The brush preferably comprises a brush body made of metal (corresponding to the solidified
molten metal), a plurality of metal wires having a first portion coupled with the brush body and a
second free portion, designed to perform brushing when the brush body is rotated about its
relative axis,
According to the invention, the brush body made of metal is formed from molten metal (with
melting temperature less than 2000°C) and the first portion of the wires is incorporated in and
connected to the brush body in such a way as to form a single metal body.
Thus, the industrial brush according to this invention is characterised in that the brush body
comprises a binding metal wherein the part of the ring which holds together the metal wires
(ring nut and inner ring) or only the ends of the wires is locked. In other words, the metal
incorporates the first portion of the wires in such a way as to make the brush body rigid.
More precisely, in the brush according to this invention, unlike prior art brushes, the second
portion of wires, in use not embedded, is also made from drawn metal.
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By using molten metals, more specifically aluminium alloys with melting temperature of from
700°C to 800°C, with which the molten metal is fed into the cavity of the mould, and is
contained within the range of temperatures for molecular restructuring of the metal wires which
are made of carbon steel or stainless steel.
The molecular contact between the various metals (of the brush body and of the wires)
improves the mechanical characteristics of the wires (lower fragility, etc which is achieved in the
wires during their drawing step or machining for construction of the brush) and in the case of
stainless steels with austenitic crystalline structure there is a reduction or even elimination of
the residual magnetism (also in this case it is due to the operation for drawing the wires).
Moreover, the brush body constructed in a single block allows a precise alignment of the axis of
the brush with the axis of rotation during its operation with consequent balancing of the brush
itself (it should be noted that the process is repeatable for all the brushes which are produced).
This operation is perfectly repeatable for the centring elements present in the moulds and in the
constructional details with which the crimped wire or twisted bundle rings are assembled.
This balancing of the brush can also be improved (depending on requirements) by removing
material from the brush body, where required, by normal mechanical machining and without
adversely affecting the compact structure of the brush body.
The metal used for forming the brush body must be such that it can be melted at a temperature
of less than 2000°C so as not create problems for the metal wires and for any metal
components that may be comprised in the brush for its forming (ring nut, support ring, etc.).
It should be noted that the use of an aluminium alloy for forming the brush body allows the
following advantages to be achieved for the brushes:
- rigid mechanical anchoring of the elements which make up the brush;
- complete recycling of the brush once worn;
- excellent legibility of the use and safety data marked on the brush body;
- improvement of the mechanical characteristics of the metal wires;
- possibility of directly threading the brush body with possibility of reducing the storage and
transport costs (it is known that the thread has a diameter greater than those commercially
used, which are obtained by coupling the thread with a special adaptor);
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- rigid constraint of the metal wires of the brush constant over time, in such a way that the
metal wires are not affected by the increase in temperature during the use of the brush or
the speed of operation or the breakage of other wires during the operation of the brush;
- excellent chemical resistance of the metal die which does not generate any type of dust
during use (and, thus, no pollution of the brushed surfaces);
- with the use of the aluminium alloy, since it is an excellent electrical conductor, there is no
difference in electrical potential between the various components (especially using metal
wires made of brass).
- possibility of having fully non-magnetic brushes using wires and elements for holding the
wires made from non-magnetic materials (such as for example, brass or the like).
Advantageously, in this way the difference in potential between the different parts (elements) of
the brush is substantially zero (equal to 0 Volts).
In effect, the casting made of aluminium (or an aluminium alloy) generates a continuous
electrical contact between the components of the brush (that is, without gaps) which gives the
object a perfect electrical conductivity.
Preferably, the brush also comprises an annular body positioned around a disc-shaped body to
form a circular crown to be passed through by the first portion of wires designed to lock them
together for positioning inside the mould.
The annular and disc-shaped bodies are also incorporated in the metal in such a way as to
form a single brush body made of metal.
Preferably, the metal brush body is equipped with first threaded constraint means. Still more
preferably, the first constraint means comprise a threaded hole made directly in the brush body,
at its axis of rotation, and a tubular adapter fixed by screwing in the threaded hole to allow the
connection between the brush body and a system for its movement.
Alternatively, or in combination, the brush body is equipped with external constraint means
designed for being connected to a body of a modular brush.
Moreover, preferably, an outer surface of the brush body defines a plurality of reinforcement
protrusions or holes for the load-bearing structure of the brush in the zones most highly
stressed during its operation.
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To increase the mechanical strength of the brush body, it preferably has a plurality of
reinforcement fins and/or through holes for conveying the air to zones where the brushing
occurs.
It should be noted that, according to the method described above, the brush body, the metal
wires, the annular body (where present) and the disc-shaped body (where present) are made
from non-sparking and nonmagnetic materials, preferably selected from the following list:
- brass;
- copper or copper alloys;
- aluminium or aluminium alloys.
Brief description of the drawings
Further features and advantages of this invention are more apparent from the non-limiting
description which follows of a preferred, non-limiting embodiment of an industrial brush as
illustrated in the accompanying drawings, in which:
- Figure 1 shows a cross-section of a cup-shaped brush according to this invention with a ring
of crimped metal wires embedded in the brush body 2;
- Figure 2 shows a cross-section of a cup-shaped brush according to this invention with
twisted bundles ring embedded in the brush body 2;
- Figure 3 shows a cross-section of a cup-shaped brush according to this invention with
twisted bundles ring and with metal elements to have a precise positioning of the brush
inside the cavity of the mould for injection moulding or by casting embedded in the brush
body 2;
- Figure 4 shows a brush unit for machining processes according to a further embodiment;
- Figure 5 shows a schematic side view of a step of the production method in question for
making a different type of brush, that is, a circular-type brush with shank;
- Figure 6 shows a view of the circular brush produced using aluminium flanges produced by
injection moulding or by casting;
- Figures 7 and 8 show a mould and a twisted bundles brush made using the mould
according to this invention.
Detailed description of preferred embodiments of the invention
With reference to the accompanying drawings, the numeral 1 denotes an industrial brush
according to this invention.
15
The brush 1 comprises a brush body 2 and a plurality of metal wires.
The wires have a first portion 3 embedded in the metal brush body 2 and a second portion 4
designed to perform brushing when the brush 1 (that is, the brush body 2) is rotated about its
relative longitudinal axis 5.
Originally, the brush body2 is formed by a molten metal in which the first portion of the metal
wires 3 is fed; the binding metal incorporates the first portion of the wires 3 to make it rigidly
integral with the brush body 2.
The above-mentioned brush 1 is made with a method having a step of preparing a plurality of
metal wires positioned in such a way as to form at least one bundle having a predetermined
width such as to occupy a predetermined space.
The metal wires are positioned inside a cavity of a mould having a predetermined geometrical
shape, in which a molten metal is subsequently fed until filling the mould.
Lastly, the molten metal is cooled to allow the solidification with the first portion 3 of metal wires
inside, so as to form a single brush body 2 from which the second portion 4, in use not
embedded, of the metal wires protrudes, designed to perform the brushing operation.
Thus, the metal brush body 2 originally comprises a rigid block encapsulating the wires or the
ring with the wires, obtained by solidifying a molten metal in a mould 8 (for example, by casting
or injection moulding).
It should be noted that the method comprises a tempering of the metal wires, made by the
molten metal fed into the mould 8 on the first portion 3 of the wires and by the mould 8 (or by
auxiliary components) on the second portion 4.
More specifically, the method comprises, between the preparing step and the feeding step, a
step for locking the metal wires inside the cavity transversely to a direction of extension of the
metal wires by at least one necking 30 having a width less than the predetermined width of the
bundle in such a way as to compress the bundle causing a separation of the metal wires into
the first portion 3 and into the second portion 4 (that is, delimiting also the brush body 2).
16
It should be noted that the necking 30 is maintained keeping in contact with the wires so as to
perform a tempering of the wires.
In the circular brushes (Figure 3), the metal wires extend in a radial direction starting from a
central annular body 16.
In this embodiment, the mould 8 has at least one half-part 8a equipped with an annular
protrusion 30a, concentric with the annular body 16 and extending transversely to the wires for
compressing them so as to form the necking 30 and delimit the radial extension of the brush
body 2.
Preferably, the mould comprises 8 two half-parts 8a each equipped with a relative annular
protrusion 30a opposite the annular protrusion of the other half-part 8a for forming the necking
30.
On the other hand, to make a circular brush with twisted bundles (Figures 7 and 8), in which
each bundle is angularly spaced from the adjacent one, the mould 8 comprises a central hollow
portion 32, wherein a first portion 33a of the twisted bundles, in use embedded in the brush
body 2, is positioned.
Starting from the central hollow portion 32, the mould comprises a plurality of radial ducts 34
housing the second portion 33b, in use not embedded, of the twisted bundles, which keep in
contact the respective second portion 33b for performing the tempering and the perfect centring
of the ring with respect to the axis of rotation.
Preferably, also in this case the mould 8 is defined by two superposable half-moulds 8a, each
equipped with a central cavity 32a and a plurality of radial grooves 34a extending from the
central cavity 32a.
Each groove 34a superposes a corresponding groove 34a of the other half-mould 8a to make
the ducts 34 during the casting.
Thus, the twisted bundles brush obtained in this way comprises a brush body 2 formed by a
disc 35 equipped along a relative periphery with a plurality of angularly spaced openings 36 in
which the wires (that is, the first portion of the bundles) are housed.
17
In the cup shaped brushes (Figure 1), on the other hand, the step of locking the the metal wires
comprises the following steps:
- positioning a disc-shaped body 10 substantially concentric with an axis of rotation of the
brush;
- positioning metal wires on the perimeter of the disc-shaped body 10;
- positioning an external annular body 9, in such a way as to define a circular crown for
housing the metal wires interposed between the discshaped body 10 and the annular body
9 so as to form the necking 30.
Moreover, preferably, the locking step also comprises a sub-step of preparing a metal bushing
31 made from a different material from the molten metal and from the metal wires and having a
diameter less than a diameter occupied by the second portion 4, in use not embedded, of the
metal wires.
Also, there is a further sub-step of inserting the second portion 4 of the metal wires in the
bushing 31 for further reducing the radial extension of the metal wires (in particular of the
second portion 4).
Therefore, the bushing 31 in turn forms a further portion of the necking 30. It should be noted
that, after the cooling, there is a step for removing the bushing 31 to complete the making of the
brush 1.
With regard to the materials, preferably the binding metal consists in a metal in the liquid phase
with a melting temperature of less than 2000°C and then solidified around the first portion of the
wires 3 to incorporate them in the brush body 2.
Preferably, the metal brush body 2 is made of aluminium or an aluminium alloy (melting
temperature approximately 800°C).
Preferably, the brush body 2 made of molten metal forms a recess 6 inside.
The purpose of the recess 6 is to facilitate a connection of the brush 1 to a spindle, that is, to a
rotary shaft for rotating the brush during the brushing. However, it should be noted that the
presence of the recess 6 is not essential, as the brush 1 could be connected to means for
rotating the brush using jaws or other connecting means.
18
However, the presence of the recess is advantageous as it facilitates the coupling of the brush
1 to the spindle; in addition, there are no tolerances in the centring of the brush when this is
fixed to the spindle.
For this reason, in the embodiment shown in Figure 1 the brush 1 comprises a particularly
reduced number of components, that is, it comprises only a ring with metal wires 3 embedded
in the brush body 2 formed by the solidified metal.
For this reason, the brush 1 is free of reduction device, as well as flange and cups which are
replaced by the solidified metal which considerably improves the mechanical characteristics
compared with the current standard.
In light of this, the recess 6 also forms internally a thread to allow screwing of the brush body 2
to the spindle.
Figure 2 shows a brush 1 equipped with the recess 6 and the flange with twisted bundles 7.
According to another embodiment of this invention (shown in Figure 3), the brush also
comprises a brush body made of molten metal with a geometrical shape suitable for the circular
brush with embedded inside a ring with crimped metal wires and with a central hole 6.
According to another embodiment of this invention (shown in Figure 4), the circular brush is
obtained from a ring with twisted bundles embedded in the metal brush body 2 with a central
hole 6.
This facilitates, advantageously, the screwing of the circular brush 1 to a spindle; if necessary,
the metal die can be threaded directly thereby avoiding the presence of the reduction device.
The cup-shaped brush shown in Figure 5 comprises metallic elements (outer ring 9 and inner
cup 10) for the perfect centring of the brush inside the cavity of the mould 8 and an inner flange
10 for holding the metal wires or bundles (as in this case it is not possible to use the ring nut
with metal wires for the crimped wire or the drilled holes for the twisted bundles).
The metallic ring 9 with the inner flange 10 are used to have a precise centring of the metal
wires with respect to the axis of rotation and to keep them stationary during the moulding step
(by casting or injection).
19
In Figure 6 the brush tool 1 comprises basically a first portion comprising a brush body 2 which
will be formed by the free space inside the mould 8 and a first portion of wires 3 positioned
inside the mould.
The method comprises the following steps:
- preparing a portion of the above-mentioned set of metal wires 3 inside a cavity of the mould
8 having a suitable geometrical shape
- feeding a metal in a molten form inside the above-mentioned cavity of the mould 8 until
filling the cavity through the hole 11.
- solidifying the molten metal with a portion of the set of metal wires 3 locked inside to form a
brush unit 1 (see Figures 7 and 8).
Looking at the method in more detail, the above-mentioned step of preparing the portion of
wires 3 can be, for example, a manual positioning introduced in the special cavity of the
mould 8.
The cavity of the mould 8 is then closed with a second mobile part 8A of the mould.
The above-mentioned step of feeding the liquid material occurs, preferably, but without
restricting the scope of the invention, through the holes 11 of the mould 8.
Purely by way of an example, the above-mentioned feeding step can be achieved by injecting
molten metal (preferably aluminium or an aluminium alloy) inside the mould 8, or (see Figure 6)
by casting the molten metal inside the mould 8 with passage of the liquid through the area 1
engaged by the set of wires 3.
Obviously the feeding methods can be of various kinds depending on the shape of the cavity of
the mould 8 and on the final shape of the brush body 2.
Figure 10 shows, by way of an example, a mould 8 for circular brushes 1 with supporting shank
12 to confirm the universal nature of the production method.
Figure 11 shows a circular brush with synthetic or natural wires with flanges 16 and 17 made of
aluminium, produced with moulding by casting or injection, wherein they are pressure fitted
relative to each other and with special configurations.
20
In the figure they are shown for example with a toothing 18 in their inner part (to lock the wires).
In both cases described above, the brush 1 can be obtained in different combinations (with
metal or synthetic wires); the liquid material can comprise a metal alloy (aluminium-based) and
the set of wires 3 must be made of metal or if the elements are moulded in aluminium the wires
3 can be made from metallic or synthetic or natural material.
In general, the brush 1 for mechanical processes therefore comprises the metal brush body 2
which constitutes the means of joining with the above-mentioned set of metal wires 3 to form a
single compact rigid body.
Basically, it may be said that the brush body 2 forms, in a first solution, the actual brush body
and also the means of retraining the set of wires 3 to the brush body 2, whilst the free part of
the wires 4 is used to perform the brushing.
At a structural level, the above-mentioned first restraining means 6 can comprise a thread
made inside the brush body 2.
Alternatively, the brush body 2 can form an intermediate element of association (compaction in
a single body) of the above-mentioned set of wires 3 and where the brush body 2 is equipped
with the above-mentioned restraining means 13 (see Figures 7, 8 and 9).
This intermediate brush element 1 is equipped, on the relative outer surface, of the abovementioned
restraining means 13 matchingly shaped to be associated, in a removable fashion
(that is to say, reversibly), with the second restraining means 15 presented by a relative brush
body 14 operating inside at least one relative cavity 15 for removably housing the brush
element 1.
As may be seen in Figures 7 and 9, the first and second removable restraining means 13 and
15 comprise a relative thread made, respectively, inside the above-mentioned cavity 15
presented by the brush body 14 and on the surface of the brush element 1.
If the threads are made on the brush element 1 , the shape of the brush body 2 can be
substantially cylindrical.
21
Alternatively, the brush element 1 can have a substantially frusto-conical shape (see figure 8) of
the brush body 2 and the application of the brush body 14 can be by interference using the
precision characteristics of the brush element 1.
Figure 9 shows, by way of a non-limiting example, a brush 14 made with the brush element 1
(see Figures 7 and 8) and wherein there is a plurality of sets of wires 4 to form the abovementioned
second portion of the wires which perform the brushing.
The second portion of wires 4 is therefore formed by a corresponding plurality of brush
elements 1 joined in a single body 14 using the above-mentioned first removable restraining
means 13 to a single brush body 14 equipped with a corresponding plurality of cavities 15
equipped with relative second restraining means.
In practice, a modular brush is formed.
The method just described and the brush element obtained achieve the pre-set aims thanks to
the simple and fast steps designed to obtain an extremely compact final product, with high
technical characteristics and reduced cost.
The homogeneous casting of the molten metal and the set of metal wires with the brush body 2
achieves a modular brush with high mechanical strength with consequent improvement of the
operational speeds and the necessary safety thanks to the mechanical locking axis of the
various brush elements 1.
Another solution concerns the making of the elements (flanges, cups or the like) with the same
process, which can be used in place of those currently used for the brushes.
The method allows a repeatability of the construction standard of the brush in a fast and precise
fashion with considerable reductions in the costs and with materials which define characteristics
of safety and lightness of the brush element and of the brush which cannot be achieved by
traditional brushes.
By exploiting the characteristics of the metals (such as for example aluminium and its alloys)
and using brass wires, brushes are obtained which are fully explosion-proof and non-magnetic
if elements made with non-magnetic metals are also used for holding the brass wires.
22
WE CLAIM:
1. A method for making a brush or brush element (1) comprising a first portion of wires (3)
embedded in the brush body (2) made of metal and a second portion of free metal wires
(4), comprising at least the following steps:
- preparing a plurality of metal wires positioned in such a way as to form at least one
bundle having a predetermined width such as to occupy a predetermined space; the
wires having a first portion (3), in use embedded in the brush body (2), and a second
portion (4), in use not embedded;
- preparing a portion of the metal wires inside a cavity of a mould having a
predetermined geometrical shape;
- feeding a molten metal inside the cavity of the mould until the cavity is filled;
- cooling the molten metal to allow the solidification with the first portion (3) of metal
wires inside, so as to form a single brush body (2) from which the second portion (4),
in use not embedded, of the metal wires protrudes, designed to perform the
brushing operation,
characterised in that it comprises a step for tempering the metal wires carried out by
the molten metal fed into the mould (8) in the first portion (3) of the wires and by the
mould (8) itself or by auxiliary components in the second portion (4).
2. The method according to claim 1, characterised in that it comprises, between the
preparing step and the feeding step, a step for locking the metal wires inside the cavity,
transversely to a direction of extension of the metal wires themselves, by at least one
necking (30) having a width less than the predetermined width of the bundle in such a
way as to compress the bundle causing a separation of the metal wires into the first
portion (3), in use embedded, and into the second portion (4), in use not embedded; the
necking (30) being in contact the wires so as to perform a tempering of the wires.
3. The method according to claim 1 or 2, characterised in that metal wires extend with a
radial direction staring from a central annular body (16) for forming a circular brush; the
mould (8) having at least one half-part (8a) equipped with an annular protrusion (30a),
concentric with the annular body (16) and extending transversely to the wires for
compressing them so as to form the necking (30) and delimit the radial extension of the
brush body (2).
23
4. The method according to claim 3, characterised in that the mould comprises (8) two
half-parts (8a) each equipped with a relative annular protrusion (30a) opposite the
annular protrusion of the other half-part (8a) for forming the necking (30).
5. The method according to any one of the preceding claims, characterised in that the
mould (8) comprises a hollow central portion (32) and a plurality of radial ducts (34)
extending from the central portion (32); the positioning step being performed by locating
the first portion (3) of the wires in the central position (32) and the second portion (4) in
the ducts.
6. The method according to claim 5, characterised in that the wires are twisted bundles
(33) and the positioning step comprises locating each twisted bundle (33) with a radial
and angular orientation spaced from the adjacent twisted bundle (33).
7. The method according to claim 5 or 6, characterised in that the mould (8) is defined by
two superposable half-moulds (8a), each equipped with a central cavity (32a) and a
plurality of radial grooves (34a) extending from the central cavity (32a); each groove
(34a) being superposable with a corresponding groove (34a) of the other half-mould
(8a) for making the duct (34) during the casting.
8. The method according to claim 1 or 2, characterised in that the step of locking the metal
wires comprises the following steps:
- positioning a disc-shaped body (10) substantially concentric with an axis of rotation
of the brush;
- positioning metal wires on the perimeter of the disc-shaped body (10);
- positioning an external annular body (9), in such a way as to define a circular crown
for housing the metal wires (3) interposed between the disc-shaped body (10) and
the annular body (9) so as to form the necking (30).
9. The method according to claim 8, characterised in that the locking step also comprises
the following sub-steps:
- preparing a metal bushing (31) made from a different material from the molten metal
and from the metal wires and having a diameter less than a diameter occupied by
the second portion (4), in use not embedded, of the metal wires;
24
- inserting the second portion (4) of the metal wires in the bushing (31) for further
reducing the radial extension of the metal wires.
10. The method according to claim 9, characterised in that the bushing (31) has an axial
extension greater than or equal to the second portion (4) of the metal wires in such a
way as to remain in contact with it during the feeding step so as to perform a complete
tempering of the metal wires.
11. The method according to claim 9 or 10, characterised in that it comprises a step of
removing the bushing (31) following the cooling step.
12. The method according to any one of the preceding claims, characterised in that it
comprises a step for defining first constraint means (6, 13) on the brush body (2)
designed to allow reversible connection with second constraint means complementary
to them, defined by an operational support or modular brush.
13. The method according to claim 12, characterised in that the step for defining the first
constraint means (6, 13) comprises a step for making a threaded cavity inside the brush
body (2).
14. The method according to claim 12 or 13, characterised in that the step for defining the
first constraint means (6, 13) is performed at the same time as the step for feeding
molten metal into the cavity of the mould (8).
15. The method according to any one of the preceding claims, characterised in that the
molten metal comprises aluminium or aluminium alloys and that the set of wires (3) is
made of metal.
16. A brush or brush element (1) for industrial or hobby purposes comprising:
- a brush body (2) made of metal;
- a plurality of metal wires having a first portion (3) coupled with the brush body (2)
and a second free portion (4), designed to perform brushing when the brush body
(2) is rotated about its relative axis (5),
characterised in that the brush body (2) made of metal is formed from molten metal
and that the first portion (3) of the wire is incorporated in and connected to the brush
25
body (2) in such a way as to form a single metal body; the second portion (4) of the
wires, in use not embedded, being made from tempered metal.
17. The brush according to claim 16, characterised in that it comprises an annular body (9)
positioned around a disc-shaped body (10) to form a circular crown to be passed
through by the first portion of wires (3) designed to lock them together for positioning
inside the mould; the annular body (9) and the disc-shaped body (10) being
incorporated in the metal in such a way as to form a single brush body (2) made of
metal.
18. The brush or brush element (1) according to claim 16, characterised in that the brush
body (2) is formed by a disc (35) equipped along a relative periphery with a plurality of
angularly spaced openings (36) in which the wires are housed.
19. The brush or brush element (1) according to claim 16 or 18, characterised in that the
metallic brush body (2) is equipped with first threaded constraint means (6).
20. The brush or brush element (1) according to any one of claims 16 to 19, characterised in
that the first constraint means (6) comprise a threaded hole made directly in the brush
body (2), at its axis of rotation (5), and a tubular adapter fixed by screwing in the
threaded hole to allow the connection between the brush body and a system for its
movement.
21. The brush or brush element (1) according to any one of claims 16 to 20, characterised in
that the brush body (2) is equipped with external constraint means (13) designed for
being connected to a body (14) of a modular brush.
22. The brush or brush element (1) according to any one of claims 16 to 21, characterised in
that an outer surface of the brush body (2) defines a plurality of reinforcement
protrusions or holes for the load-bearing structure of the brush in the zones most highly
stressed during its operation.
23. The brush or brush element (1) according to any one of claims 16 to 22, characterised in
that the brush body (2), the metal wires, the annular body (9) and the disc-shaped body
(10) are made from non-sparking and non-magnetic materials.
26
24. The brush or brush element (1) according to claim 23, characterised in that nonsparking
and non-magnetic materials are selected from the following list:
- brass;
- copper or copper alloys;
- aluminium or aluminium alloys.