DESCRIPTION
TECHNICAL FIELD
The invention relates to press tools and more
particularly, but not exclusively, to press tools for
forming or shaping into an annular form of desired
dimensions the end turns of wound wire coils of the stator
of an electrical machine such as an electric motor.
BACKGROUND ART
It is known to provide a forming press and tooling to
form the end turns of the wound wire coils of a stator into
an annulus of given external and internal diameters and
axial length in a three stage process in which outer
segments of the tooling contract to compress the end turns
to define the outer diameter of the annulus, inner segments
of the tooling expand to compress the end turns to define
the inner diameter of the annulus and an annular end member
is moved axially against the end turns to compress the end
turns to define the axial length of the annulus.
A problem associated with the known tooling is that
during the movement of the inner and outer segments and/or
the end member, it is sometimes possible for the wire of
the end turns to become trapped between the parts of the
tooling so that the coils are damaged.
It is an object of the invention to provide tooling
which will prevent or at least mitigate this problem.
DISCLOSURE OF INVENTION
According to the invention a press tool for forming
a compressible mass into an annulus of given inner and
outer diameters and axial length comprises radially movable
inner and outer tool parts adapted to expand and contract
respectively to form the mass to the desired inner and
outer diameters, each of which tool parts comprises a first
array of radially movable members, each of which members is
formed with a head having a working face curved to the
desired diameter, and each of which tool parts comprises a
second array of radially movable members which are
interposed between the respective members of the first
array and which each have a head having a working face, a
central portion of which working face is curved to the
desired diameter and opposed sloping outer portions of
which are shaped for sliding contact against rear faces of
the heads of respective adjacent members of the said first
array, whereby the first and second arrays of movable
members can be moved radially to compress the compressible
mass into the desired diameter and so that during at least
a part of the radial movement, the heads of the first and
second arrays form continuous substantially annular
surfaces, and an axially movable annular member having a
working face for forming the compressible mass to the
desired axial length. Preferably the radially movable
members and the annular member are mounted in a common body
which may, for example, be plate-like or annular.
Preferably the axially movable annular end member is
arranged in its axially retracted position to have its
working face flush with a surrounding stationary body part
substantially to eliminate gaps into which the compressible
mass might become trapped.
The means for actuating the radially and axially
movable parts of the press tool may be generally
conventional, i.e. cam means, wedge means or the like and
the actuating means may be under the control of one or more
hydraulic rams, electrical actuators or the like.
From another aspect the invention is a forming press
comprising tooling as described above.
Although the apparatus referred to in the
description and claims is said to be for the purpose of
forming a compressible mass into an annulus of given size,
it will be appreciated that the apparatus may be used to
form generally analogous shapes by suitably configuring the
working faces of the movable members. Thus the faces of
the members may be flat or comprise a series of flats, so
that the movable members together form a compressible mass
to a generally annular shape. References to the curved
working faces of the movable members should be construed
accordingly.
BRIEF DESCRIPTION OF DRAWINGS
The invention is diagrammatically illustrated, by way
of example, in the accompanying drawings in which:-
Figure 1 is an end view of an inner tool part of a
press tool for forming a compressible mass, e.g. the end
turns of the wound wire coils of a stator into an annulus,
shown in a retracted position;
Figure 2 is a view of the inner tool part of Figure 1
shown in a radially expanded position;
Figure 3 is an end view of an outer tool part for a
press tool for forming a compressible mass e.g. the end
turns of the wound wire coils of a stator, shown in a
retracted position;
Figure 4 is an end view of the tool part of Figure 3
shown in a radially contracted position, and
Figure 5 is a sectional side view of the press tool of
Figures 1 to 4 and showing the inner and outer tool parts
and a radially movable ring member for forming the annular
compressible mass to a desired axial length, shown in both
their retracted and advanced positions.
BEST MODE FOR CARRYING OUT THE INVENTION
In the drawings there is shown a press tool 1 for
forming or shaping a compressible mass in the form of the
end turns 5 of the wound wire coils in a stator 32 of an
electrical machine. The press tool 1 comprises outer and
inner tool parts 3 and 4 respectively for forming the
required inner and outer diameters to the end turns 5 and
an axially movable annular member 29 for forming the axial
length of the end turns 5 in a three stage process, known
per se. In the known process the outer and inner tool
parts, which are usually segmental in shape, are moved
sequentially against the end turns 5 to form them to the
required inner and outer diameters after which the end
member is moved against the end turns 5 while they are held
compressed by the outer and inner tool parts to form the
end turns to the required axial length.
Referring more particularly to Figures 1 and 2 of the
drawings, the inner part 4 of the press tool consists of a
first radial array of radially movable members 11 each of
which has a head 15 having a convexly curved working face
19 and a rear face 26. Interposed between each member 11
is one of a second radial array of radially movable members
12 each of which has a head 16 having a working face 20, a
central portion 22 of which is convexly curved and opposed
outer portions 23 of which slope away from the central
portion 22. The arrangement is such that the sloping parts
23 of the heads 16 of the members 12 are in sliding contact
with the rear faces 26 of the heads 15 of the members 11.
The members 11 are formed with inwardly extending
radial stems 33 and the members 12 are formed with
corresponding inwardly extending radial stems 34. The
stems 33 and 34 are slidingly supported and guided in
portions 36 and 37 of a body part 2 of the tool 1, see
Figure 5. The inner ends of the stems 3 4 are contacted by
actuating means (not shown) but generally conventional per
se e.g. cams, wedge devices or the like so that the members
11 and 12 are movable radially outwardly from the position
shown in Figure 1 of the drawings to the position shown in
Figure 2 of the drawings to bear against the end turns of
the wire coil to form the end turns to the required inner
diameter. In this condition the working surfaces together
form a continuous annular surface 28.
In the known tooling the movement of the segmental
parts of the tooling tends to trap individual wires of the
coil between the segmental parts as they are advanced and
retracted. In contrast the tooling shown in Figures 1 and
2 is arranged such that the inner and outer arrays of
moving segmental tool parts 11,12 are arranged not to form
contracting gaps during their advance but instead form a
continuous smooth surface as shown in Figure 2. Any gaps
between the parts which may be present when the tool is
retracted into its open condition are arranged to expand
and disappear during the tool advance. The members 11 and
12 are biased into the retracted position shown in Figure
1 by resilient means e.g. springs or rubber rings, etc. in
known manner.
The outer tool part 3 shown in Figures 3 and 4 is
generally similar to that described above with reference to
the inner tool part 4 and comprises a first radial array of
movable members 9 and a second radial array of movable
members 10 disposed radially between the members 9, the
members 9 and 10 being slidably mounted in the body 2 for
radial movement. The members 9 have heads 13 formed with
concavely curved working faces 17 and rear faces 25 and the
members 10 of the second array have heads 14 having working
faces 18, a central portion 21 of which is concavely curved
and opposed outer portions 24 of which slope away from the
central portion and are arranged for sliding contact with
the rear faces 25 of the heads 13 whereby when the members
9 and 10 are contracted from the position shown in Figure
3 to the position shown in Figure 4 by generally
conventional actuating means (not shown), the working faces
of the heads 9 and 10 together form a substantially
continuous annular face of the required diameter to
compress the end turns of the stator to its required outer
diameter. It will be noted that, unlike known forming
tools, the parts 9 and 10 form a substantially continuous
surface during the contraction from the retracted position
shown in Figure 3 to the advanced position shown in Figure
4 to prevent trapping and damaging the coil during the
forming process.
In Figure 5 there is shown an axial section of the
tooling of Figures 1 to 4 having a centre line shown by
chain dashed line 35. To the right of the centre line the
tool parts 3,4 are shown in the retracted positions as
indicated in Figures 1 and 3. In this position an axially
movable annular member 29 slidably mounted in the tool body
2 is arranged to have its working face 30 flush with
stationary inner and outer parts 31 and 3 7 of the body 2 so
as to eliminate gaps between the tool parts to prevent the
possibility of trapping any part of the coils to be formed.
The left hand portion of Figure 5 shows the inner and
outer tool parts advanced into contact with the end turns
5 to form the end turns to the required inner and outer
diameters, and shows the axially movable annular member 29
advanced into its working position in which it slides
between the outer and inner parts 3 and 4 and contacts the
exposed axial end turns 5 of the coil to form the end turns
into the required axial length.
INDUSTRIAL APPLICABILITY
Among the advantages of the press tool shown in the
drawings are the following:-
1. the press tool permits a reduction in the size of the
forming cavity or cavities when open due to the
substantial elimination of wire traps. This enables
the tool to operate with reduced working strokes which
reduces the cycle time of the tool to increase
productivity. The reduced cavity size also permits
the use of smaller tools. This in turn facilitates
standardisation of tooling;
2. the press tool can be utilized to centralise relative
to the stator core the coils to be formed prior to the
forming step due to the lack of wire traps in the
forming cavity. This eliminates the need for a
separate centralizing device and again aids
productivity, and
3. due to the absence of wire traps in the forming
cavity, the degree of wire compression during forming
can be increased to raise the conductive metal, e.g.
copper, content of the end turns of the coils.
The invention thus provides tooling for forming
compressible masses, e.g. the wound wire coils of stators
to require sizes and which obviates or reduces problems
associated with known tooling of this kind.
WE CLAIM:
1. A press tool (1) for forming a compressible mass (5)
into an annulus of given inner and outer diameters and
axial length, the tool having radially movable outer and
inner tool parts (3,4) adapted to expand and contract
respectively to form the mass (5) to the desired inner and
outer diameters, and an axially movable annular member (29)
having a working face (30) for forming the compressible
mass (5) to the desired axial length, characterised in that
each of the tool parts (3,4) comprises a first array of
radially movable members (9,11), each of which members
(9,11) is formed with a head (13,15) having a working face
(17,19) curved to the desired diameter, and in that each of
the tool parts (3,4) comprises a second array of radially
movable members (10,12) which are interposed between the
respective members of the first array (9,11) and which each
have a head (14,16) having a working face (18,20), a
central portion (21,22) of which working face is curved to
the desired diameter and opposed sloping outer portions
(23,24) of which are shaped for sliding contact against
rear faces (25,26) of the heads (13,15) of respective
adjacent members of the said first array, whereby the first
and second arrays of movable members can be moved radially
to compress the compressible mass into the desired diameter
and so that during at least a part of the radial movement,
the heads (13,14,15,16) of the first and second arrays form
continuous substantially annular surfaces.
2. A press tool according to claim 1, characterised in
that the radially movable members (9,10,11,12) and the
annular member (29) are mounted for movement in a common
body (2).
3. A press tool according to claim 1 or claim 2,
characterised in that the axially movable annular end
member (29) is arranged in its axially retracted position
to have its working face (30) flush with a surrounding
stationary body part (31,37) substantially to eliminate
gaps into which the compressible mass might become trapped.
4. A press tool according to any one of claims 1 to 3,
characterised by means for actuating the radially and
axially movable parts of the press tool.
5. A press tool according to any preceding claim, for
forming the end turns of wound wire coils of an electrical
machine.
6. A forming press characterised by a press tool (1) as
claimed in any one of claims 1 to 5.
7. A press tool, substantially as herein described,
particularly with reference to, and as illustrated in the
accompanying drawings.
8. A forming press, substantially as herein described,
particularly with reference to, and as illustrated in the
accompanying drawings.
9. A press tool for forming a compressible mass into an
annulus of given inner and outer diameters and axial length,
substantially as herein described, particularly with
reference to, and as illustrated in the accompanying
drawings.

A press tool (1) for forming a compressible mass (5)
into an annulus of given inner and outer diameters and
axial length, the tool having radially movable outer and
inner tool parts (3,4) adapted to expand and contract
respectively to form the mass (5) to the desired inner and
outer diameters, and an axially movable annular member (29)
having a working face (30) for forming the compressible
mass (5) to the desired axial length, characterised in that
each of the tool parts (3,4) comprises a first array of
radially movable members (9,11), each of which members
(9,11) is formed with a head (13,15) having a working face
(17,19) curved to the desired diameter, and in that each of
the tool parts (3,4) comprises a second array of radially
movable members (10,12) which are interposed between the
respective members of the first array (9,11) and which each
have a head (14,16) having a working face (18,20), a
central portion (21,22) of which working face is curved to
the desired diameter and opposed sloping outer portions
(23,24) of which are shaped for sliding contact against
rear faces (25,26) of the heads (13,15) of respective
adjacent members of the said first array, whereby the first
and second arrays of movable members can be moved radially
to compress the compressible mass into the desired diameter
and so that during at least a part of the radial movement,
the heads (13,14,15,16) of the first and second arrays form
continuous substantially annular surfaces.