Information
-
Patent Grant
-
6477882
-
Patent Number
6,477,882
-
Date Filed
Wednesday, February 7, 200124 years ago
-
Date Issued
Tuesday, November 12, 200222 years ago
-
Inventors
-
Original Assignees
-
Examiners
Agents
- Birch, Stewart, Kolasch & Birch, LLP
-
CPC
-
US Classifications
Field of Search
US
- 072 343
- 072 3532
- 072 3534
- 072 3548
-
International Classifications
-
Abstract
In order to obtain uniform pressing force applied to a workpiece by an ironing die and easily disengage the workpiece after completing plastic working for the workpiece, a forming machine for performing the plastic working for the workpiece has a base pedestal, a forming punch provided on the base pedestal, and an annular ironing die arranged over the forming punch. The forming punch comprises a main punch body, six punch collets to be engaged with the main punch body and separated from each other at equal angles, a metal sleeve externally fitted to the main punch body and the punch collets, and a holder for holding the metal sleeve.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a forming machine for performing plastic working for a workpiece to have a predetermined shape by applying pressing force to the workpiece by using an ironing die.
2. Description of the Related Art
For example, a forming machine, which is disclosed in Japanese Patent No. 2729852, is known as a forming machine for performing plastic working for an outer wheel of a constant velocity universal joint which is used to drive wheels of an automobile.
As shown in
FIG. 13
, the forming machine A is used as follows. That is, a workpiece D, for example, an outer wheel for a ball joint is fitted to the forward end of a main punch body C which constitutes a forming punch B. An ironing die E is moved downwardly to apply the pressing force to the workpiece D so that the inner circumferential surface of the workpiece D is subjected to plastic working to have a predetermined shape. The main punch body C is formed with a plurality of sliding contact surfaces F each of which is inclined by a predetermined angle in a direction to make approach to the axis as the position on the sliding contact surface F approaches the forward end of the main punch body C. Punch collets G, which are opposed to one another, are fitted to make sliding contact with the respective sliding contact surfaces F. The forward end of the punch collet G has a shape corresponding to the predetermined shape so that the inner circumferential surface of the workpiece D may be formed into the predetermined shape.
After the plastic working for the workpiece D is completed, an elevator plate I is moved upwardly in accordance with the action of a cylinder mechanism H so that the respective punch collets G, which are engaged with the forward end of the elevator plate I, are allowed to make sliding movement obliquely upwardly with respect to the axial direction along the sliding contact surfaces F. When the movement in the obliquely upward direction is effected, the distances between the forward ends of the respective punch collets G are narrowed as a whole. As a result, the workpiece D, which is fitted to the forward end of the main punch body C, can be disengaged from the main punch body C. That is, as the punch collets G make the sliding movement, the distances between the forward ends of the mutually opposing punch collets G are narrowed. A gap J is finally formed between the workpiece D after the plastic working and the punch collets G (see FIG.
14
). The gap J is utilized to disengage the workpiece D after the plastic working from the punch collets G. The disengaged workpiece D is transported to aftertreatment steps by the aid of a transport apparatus (not shown).
A forming punch, which is disclosed in Japanese Utility Model Publication No. 7-18448, is known as a forming punch for constructing a forming machine.
As shown in
FIG. 15
, the forming punch K has a main body section M which is formed with a female section L, and a head O which is formed with a male section N. In this form, the male section N is fitted to the female section L.
Further, a plurality of recessed grooves P are formed on an inner circumferential surface of the female section L. A plurality of recessed grooves Q, which are opposed to the recessed grooves P, are formed in the circumferential direction on an outer circumferential surface of the male section N. Key members R are fitted so that they range over the recessed grooves P and Q. The main body section M is provided with screw holes S in the diametric directions to face the aligned recessed grooves P and Q. Holding bolts T are screwed into the screw holes S. The head O is joined to the main body section M by pressing the key members R with the holding bolts T.
SUMMARY OF THE INVENTION
The present invention has been made in relation to the conventional forming machine described above, a general object of which is to provide a forming machine in which no complicated arrangement such as a cylinder mechanism is adopted, and hence an arrangement of the forming machine itself is simplified, making it possible to realize a small size and an inexpensive price.
A principal object of the present invention is to provide a forming machine which is excellent in versatility in which the forming step itself is quickened, making it possible to respond to the machining for a variety of workpieces.
Another object of the present invention is to provide a forming machine which makes it possible to suppress the occurrence of any axial deviation between an ironing die and a forming punch as less as possible, which makes it possible to improve the accuracy of plastic working for a workpiece by substantially uniformly applying the pressing force applied to the workpiece by the ironing die, and which makes it possible to easily disengage the workpiece after completing the plastic working for the workpiece.
The above and other objects, features, and advantages of the present invention will become more apparent from the following description when taken in conjunction with the accompanying drawings in which a preferred embodiment of the present invention is shown by way of illustrative example.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1
shows a vertical sectional view illustrating a forming machine according to an embodiment of the present invention;
FIG. 2
shows, with partial cross section, a perspective view illustrating a forming punch to be used in the embodiment of the present invention;
FIG. 3
shows a bottom view illustrating the forming punch;
FIG. 4
illustrates a state in which a workpiece is fitted to the forming punch;
FIG. 5
illustrates a state immediately after the workpiece is machined;
FIG. 6
illustrates a state immediately before the workpiece is disengaged from the forming punch;
FIG. 7
shows a vertical sectional view illustrating a forming machine according to another embodiment;
FIG. 8
shows, with partial cross section, a perspective view illustrating the forming punch shown in
FIG. 7
;
FIG. 9
shows a sectional view taken along a line IX—IX illustrating the forming punch shown in
FIG. 7
;
FIG. 10
illustrates a state in which a workpiece is fitted to the forming punch of the forming machine shown in
FIG. 7
;
FIG. 11
illustrates a state immediately after the workpiece is machined with the forming machine shown in
FIG. 7
;
FIG. 12
illustrates a state immediately before the workpiece is disengaged from the forming punch concerning the forming machine shown in
FIG. 7
;
FIG. 13
illustrates a state before a workpiece is machined with a conventional forming machine;
FIG. 14
illustrates a state immediately before the workpiece is disengaged from the forming machine concerning the forming machine shown in
FIG. 13
; and
FIG. 15
shows, with partial cutaway, a front view illustrating a forming punch concerning another conventional technique.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The forming machine according to the present invention will be explained in detail below with reference to the accompanying drawings
FIGS. 1
to
6
as exemplified by preferred embodiments. The way of use of the forming machine is not limited. However, for example, the forming machine is preferably used in order to produce an outer wheel of a constant velocity universal joint which is used to drive wheels of an automobile.
As shown in
FIG. 1
, a forming machine
10
according to ran embodiment of the present invention has a base pedestal
12
, a forming punch
14
which is provided on the base pedestal
12
, and an annular ironing die
16
which is arranged over the forming punch
14
.
As shown in
FIGS. 1 and 2
, the forming punch
14
comprises a main punch body
18
, six punch collets
20
a
to
20
f
which are engaged with the main punch body
18
and which are separated from each other at equal angles, a metal sleeve
22
which is externally fitted to the main punch body
18
and the punch collets
20
a
to
20
f
, and a holder
24
which fastens the metal sleeve
22
.
The main punch body
18
is made of high speed steel, and it has a substantially truncated cone-shaped configuration. The forward end
26
of the main punch body
18
is formed to be substantially flat. A placement section
27
for placing the metal sleeve
22
thereon is provided at the other end. Three pairs of mutually opposing cutout grooves
28
a
to
28
f
, which are continuous from the forward end
26
to the placement section
27
, are formed while being separated from each other at equal angles for each pair of the cutout grooves, i.e.,
28
a
and
28
d
,
28
b
and
28
e
, and
28
c
and
28
f.
The cutout groove
28
a
to
28
f
has a lateral cross section which has a substantially wedge-shaped configuration. The cutout groove
28
a
to
28
f
is defined by a sliding contact surface
30
a
to
30
f
which is inclined by a predetermined angle in a direction to make approach to the axis of the main punch body
18
(oblique direction with respect to the axis), and a tapered surface
32
a
to
32
f
which is further inclined from the sliding contact surface
30
a
to
30
f
toward the axial direction of the main punch body
18
(see FIGS.
1
and
2
).
A straight section
38
a
to
38
f
which extends vertically upwardly from the abutment surface with respect to the base pedestal
12
, and a forming section
40
a
to
40
f
which is continuous from the straight section
38
a
to
38
f
to the forward end
26
are formed on each of ridges
34
a
to
34
f
which are interposed between the respective cutout grooves
28
a
to
28
f
(see FIGS.
1
and
2
). The surface of the straight section
38
a
to
38
f
is highly accurately polished. On the other hand, the forming section
40
a
to
40
f
has a predetermined curved configuration in order to machine the inner circumferential surface of a workpiece W as described later on.
Three pairs of the punch collets
20
a
to
20
f
are arranged in the respective cutout grooves
28
a
to
28
f
while being separated from each other at equal angles and being opposed to one another for each pair of the punch collets, i.e.,
20
a
and
20
d
,
20
b
and
20
e
, and
20
c
and
20
f
so that they are fitted to make sliding movement, in the same manner as the cutout grooves
28
a
to
28
f
described above.
Each of the punch collets
20
a
to
20
f
has a leg
44
a
to
44
f
which abuts against the base pedestal
12
, a straight section
46
a
to
46
f
which extends in the vertical direction from the leg
44
a
to
44
f
, a tapered section
48
a
to
48
f
which is inclined by a predetermined angle with respect to the axis of the main punch body
18
from the end of the straight section
46
a
to
46
f
, a flat section
49
a
to
49
f
which extends from the tapered section
48
a
to
48
f
, and a curved section
50
a
to
50
f
which is continuous from the flat section
49
a
to
49
f
to a forward end surface
52
a
to
52
f
perpendicular to the axis of the main punch body
18
.
A hole
54
a
to
54
f
is formed through a holding section
53
a
to
53
f
of the leg
44
a
to
44
f
, the holding section
53
a
to
53
f
extending in the expanding direction as shown in the drawings (see FIGS.
1
and
2
). As easily and clearly understood from
FIGS. 5 and 6
as well, the axis of the hole
54
a
to
54
f
extends at an angle parallel to the sliding contact surface
30
a
to
30
f.
The surface of the straight section
46
a
to
46
f
, which is formed on the punch collet
20
a
to
20
f
, is highly accurately polished beforehand, in the same manner as the straight section
38
a
to
38
f
formed on the ridge
34
a
to
34
f
. The annular metal sleeve
22
, which has a pawl
22
a
at its first end, is externally fitted to the straight sections
38
a
to
38
f
provided for the ridges
34
a
to
34
f
of the main punch body
18
and the straight sections
46
a
to
46
f
provided for the punch collets
20
a
to
20
f
, in order to coaxially hold the main punch body
18
and the respective punch collets
20
a
to
20
f
as described above (see FIGS.
1
and
2
). The metal sleeve
22
is placed on the placement section
27
formed for the main punch body
18
, and the circumference of the metal sleeve
22
is held by the holder
24
.
A chamber
57
is formed at the inside of the holder
24
. The holder
24
has a pawl
59
which is disposed around the lower end, and it has an opening
61
which is disposed at a substantially central portion thereof. The pawl
59
is placed on the base pedestal
12
. The main punch body
18
and the punch collets
20
a
to
20
f
, to which the metal sleeve
22
is externally fitted, penetrate through the opening
61
. A plurality of bolt holes
55
, which are arranged at equal intervals, are bored through a top flat surface
63
of the holder
24
. Bolts
56
are allowed to penetrate through the bolt holes
55
to fix the holder
24
to the base pedestal
12
by means of screwing attachment (see FIG.
2
).
A plurality of screw holes
58
a
to
58
f
, which are separated from each other at equal angles, are formed through the top flat surface
63
of the holder
24
about the center of the axis of the main punch body
18
(see FIGS.
2
and
3
). The angle of inclination of each of the screw holes
58
a
to
58
f
is substantially the same as that of each of the holes
54
a
to
54
f.
First ends of guide pins
62
a
to
62
f
in the chamber
57
are screwed into the screw holes
58
a
to
58
f
. Second ends of the guide pins
62
a
to
62
f
are faced to and inserted into holes
54
a
to
54
f
which are formed through the holding sections
53
a
to
53
f
of the punch collets
20
a
to
20
f
(see FIGS.
1
and
2
).
A coil spring
64
a
to
64
f
, which is seated on the inner wall of the holder
24
and the holding section
53
a
to
53
f
, is wound around the guide pin
62
a
to
62
f
. The hole
54
a
to
54
f
, the screw hole
58
a
to
58
f
, and the sliding contact surface
30
a
to
30
f
of the cutout groove
28
a
to
28
f
formed on the main punch body
18
are in a relationship of being mutually closest to one another, and they are inclined at the identical angle with respect to the axis of the main punch body
18
. Therefore, they are in a parallel state. Accordingly, the guide pin
62
a
to
62
f
, the coil spring
64
a
to
64
f
, and the sliding contact surface
30
a
to
30
f
are inclined in parallel to one another in the same manner as described above (see FIGS.
1
and
2
).
As shown in
FIG. 1
, the ironing die
16
has a first tapered section
66
which is inclined by a predetermined angle in a direction to make mutual approach to the axis of the ironing die
16
, a straight section
68
which extends vertically upwardly from the first tapered section
66
, and a second tapered section
70
which extends from the straight section
68
and which is inclined by a predetermined angle in a direction to make mutual separation from the axis of the ironing die
16
. The ironing die
16
is connected to a driving mechanism (not shown). The ironing die
16
is movable upwardly and downwardly in the axial direction of the forming punch
14
in accordance with the action of the driving mechanism.
The forming machine
10
according to the embodiment of the present invention is basically constructed as described above. Next, its function and effect will be explained.
At first, as shown in
FIG. 4
, the workpiece W is fitted to the forming punch
14
by the aid of a transport mechanism (not shown) so that the workpiece W is opposed to the forward end
26
of the main punch body
18
which constitutes the forming punch
14
. In this procedure, the inner circumferential surface of the workpiece W is coarsely machined beforehand so that the inner circumferential surface of the workpiece W is fitted to the forming sections
40
a
to
40
f
which are formed on the ridges
34
a
to
34
f
for constructing the main punch body
18
and the curved sections
50
a
to
50
f
which are formed on the punch collets
20
a
to
20
f.
Subsequently, as shown in
FIG. 5
, the ironing die
16
is moved downwardly in the axial direction of the main punch body
18
in accordance with the action of the driving mechanism (not shown) while applying the pressing force to the outer circumferential surface of the workpiece W. Accordingly, a state is given, in which the workpiece W is interposed between the ironing die
16
and the forming sections
40
a
to
40
f
provided for the ridges
34
a
to
34
f
and the curved sections
50
a
to
50
f
provided for the punch collets
20
a
to
20
f
. The inner circumferential surface of the workpiece W is subjected to the plastic working to have a predetermined shape by the aid of the forming sections
40
a
to
40
f
. During this process, an undercut section W
1
is formed on the workpiece W so that the undercut section W
1
is coincident with the shape of the curved sections
50
a
to
50
f.
After the plastic working for the workpiece W is completed, the workpiece W is displaced vertically upwardly in accordance with the action of the transport mechanism (not shown). During this process, the undercut section W
1
, which is formed on the workpiece W as described above, allows the workpiece W to be fastened by the punch collets
20
a
to
20
f
. Thus, the punch collets
20
a
to
20
f
follow the workpiece W, and they make sliding movement in the upward direction along the sliding contact surfaces
30
a
to
30
f.
In accordance with the sliding movement of the punch collets
20
a
to
20
f
on the sliding contact surfaces
30
a
to
30
f
, the coil springs
64
a
to
64
f
, which are seated on the holder
24
and the upper surfaces of the holding sections
53
a
to
53
f
of the punch collets
20
a
to
20
f
, are contracted. Accordingly, a state is given, in which the guide pins
62
a
to
62
f
, which are screwed and attached to the holder
24
, penetrate through the holes
54
a
to
54
f
which are formed through the holding sections
53
a
to
53
f
(see FIG.
6
).
The sliding contact surfaces
30
a
to
30
f
are formed so that they are inclined by the predetermined angle in the direction to make approach to the axis of the main punch body
18
. Therefore, as the punch collets
20
a
to
20
f
slide upwardly on the sliding contact surfaces
30
a
to
30
f
, the distances between the forward ends of the mutually opposing punch collets
20
a
to
20
f
are narrowed as a whole. As a result, when the workpiece W is displaced by a predetermined distance, a gap
72
is formed between the workpiece W and the punch collets
20
a
to
20
f
(see FIG.
6
). The workpiece W can be disengaged from the punch collets
20
a
to
20
f
with ease by utilizing the gap
72
.
The disengaged workpiece W is transported to the aftertreatment step by the aid of the transport mechanism (not shown), to which a predetermined aftertreatment is applied.
Simultaneously with the disengagement of the workpiece W from the punch collets
20
a
to
20
f
, the punch collets
20
a
to
20
f
make sliding movement in the downward direction along the sliding contact surfaces
30
a
to
30
f
in accordance with the action of the resilient force of the coil springs
64
a
to
64
f
. The resilient force is applied until the punch collets
20
a
to
20
f
are returned to the positions of the state before the workpiece W is fitted to the forming punch
14
.
In the embodiment of the present invention, the metal sleeve
22
is externally fitted to the straight sections
38
a
to
38
f
and
46
a
to
46
f
which are formed on the main punch body
18
and the punch collets
20
a
to
20
f
respectively. Therefore, the punch collets
20
a
to
20
f
are reliably maintained coaxially with the main punch body
18
. Further, the surfaces of the straight sections
38
a
to
38
f
and
46
a
to
46
f
are highly accurately polished as described above. Therefore, it is possible to make the contact without providing any gap between the main punch body
18
and the punch collets
20
a
to
20
f
and the metal sleeve
22
.
Therefore, it is possible to suppress the occurrence of any axial deviation between the ironing die
16
and the main punch body
18
to which the punch collets
20
a
to
20
f
are fitted as less as possible. Accordingly, when the pressing force is applied to the workpiece W by using the ironing die
16
, the pressing force can be applied to the workpiece W substantially uniformly. Therefore, it is possible to highly accurately perform the plastic working for the workpiece W. As a result, it is possible to easily machine the workpiece W in the aftertreatment steps.
In the embodiment of the present invention, when the workpiece W is disengaged from the forming machine
10
after completing the plastic working for the workpiece W, then the workpiece W is displaced in accordance with the action of the transport mechanism (not shown), and the punch collets
20
a
to
20
f
are allowed to make the sliding movement in the upward direction along the sliding contact surfaces
30
a
to
30
f
formed on the main punch body
18
so as to follow the displacement of the workpiece W. Accordingly, the gap
72
is formed between the workpiece W and the punch collets
20
a
to
20
f
. The workpiece W can be easily disengaged from the punch collets
20
a
to
20
f
by utilizing the gap
72
.
In the embodiment of the present invention, the guide pins
62
a
to
62
f
, the coil springs
64
a
to
64
f
, and the sliding contact surfaces
30
a
to
30
f
are in the parallel state. Therefore, when the punch collets
20
a
to
20
f
make the sliding movement along the sliding contact surfaces
30
a
to
30
f
, it is possible to smoothly make the sliding movement without applying any excessive load on the punch collets
20
a
to
20
f
. After the workpiece W is disengaged, the punch collets
20
a
to
20
f
are forcibly restored to the original positions in accordance with the action of the resilient force of the coil springs
64
a
to
64
f.
Another embodiment of the forming machine according to the present invention is shown in FIG.
7
and followings.
As shown in
FIG. 7
, a forming machine
100
according to this embodiment of the present invention has a base pedestal
112
, a forming punch
114
which is provided on the base pedestal
112
, and an annular ironing die
16
which is arranged over the forming punch
114
. The ironing die
16
is the same as the ironing die to be used for the forming machine shown in
FIGS. 1
to
6
having been already explained.
Therefore, the same conformational portions are designated by the same reference numerals, detailed explanation of which will be omitted.
As shown in
FIGS. 7 and 8
, the forming punch
114
comprises a main punch body
118
, six punch collets
120
a
to
120
f
which are engaged with the main punch body
118
and which are separated from each other at equal angles, a metal sleeve
122
which is externally fitted to the main punch body
118
and the punch collets
120
a
to
120
f
, and a holder
124
which fastens the metal sleeve
122
.
The main punch body
118
is formed to have a substantially truncated cone-shaped configuration, and it comprises a punch base
126
made of die steel, and a mandrel
128
made of high speed steel. A recess
130
is formed at the upper end of the punch base
126
. An annular placement section
132
for placing the metal sleeve
122
thereon is provided at the lower end so that the placement section
132
protrudes outwardly. A first fastening hole
134
is defined at a substantially central portion in the axial direction of the punch base
126
so that the first fastening hole
134
penetrates through the punch base
126
(see FIG.
7
).
The punch base
126
is formed with a plurality of holes
136
a
to
136
f
which are disposed around the center of the axis of the punch base
126
and which are separated from each other at equal angles. The hole
136
a
to
136
f
is composed of a small diameter section
137
a
to
137
f
, and a large diameter section
139
a
to
139
f
which is formed to have a diameter larger than that of the small diameter section
137
a
to
137
f
. The axis of the hole
136
a
to
136
f
is inclined by a predetermined angle in a direction to make approach to the axis of the punch base
126
and the mandrel
128
(oblique direction with respect to the axis).
The mandrel
128
has a first end
138
which is formed to be substantially flat, and a projection
142
which is provided at a second end
140
and which is fitted to the recess
130
. Six cutout grooves
144
a
to
144
f
, which range from the first end
138
to the second end
140
, are provided on the outer circumferential surface of the mandrel
128
. In this arrangement, the cutout grooves
144
a
and
144
d
,
144
b
and
144
e
,
144
c
and
144
f
are arranged symmetrically with respect to the axis of the mandrel
128
. The projection
142
is defined with a second fastening hole
146
which is opposed to the first fastening hole
134
(see FIG.
7
).
The cutout groove
144
a
to
144
f
has a lateral cross section which has a substantially wedge-shaped configuration. The cutout groove
144
a
to
144
f
has a sliding contact surface
148
a
to
148
f
which is inclined by a predetermined angle in a direction to make approach to the axis of the mandrel
128
(oblique direction with respect to the axis). A tapered surface
150
a
to
150
f
, which is suddenly inclined in the axial direction of the mandrel
128
, extends from the sliding contact surface
148
a
to
148
f
to the first end
138
(see FIGS.
7
and
8
). The angle of inclination of the sliding contact surface
148
a
to
148
f
with respect to the axis of the mandrel
128
is set to be the same angle as the angle of inclination of the axis of the hole
136
a
to
136
f
with respect to the axis of the punch base
126
. Therefore, the axes of the holes
136
a
,
136
b
,
136
c
,
136
d
,
136
e
,
136
f
and the sliding contact surfaces
148
a
,
148
b
,
148
c
,
148
d
,
148
e
,
148
f
are in a state of being parallel to one another.
A straight section
154
a
to
154
f
which extends vertically upwardly from the abutment surface with respect to the punch base
126
, and a forming section
156
a
to
156
f
which is continuous from the straight section
154
a
to
154
f
to the first end
138
are formed on each of ridges
152
a
to
152
f
which are interposed between the respective cutout grooves
144
a
to
144
f
(see FIGS.
7
and
8
). The surface of the straight section
154
a
to
154
f
is highly accurately polished. On the other hand, the forming section
156
a
to
156
f
has a predetermined curved configuration in order to machine the inner circumferential surface of a workpiece W as described later on.
The punch collets
120
a
to
120
f
are arranged in the respective cutout grooves
144
a
to
144
f
while being separated from each other at equal angles and being opposed to one another for each pair of the punch collets, i.e.,
120
a
and
120
d
,
120
b
and
120
e
, and
120
c
and
120
f
so that they are fitted to make sliding movement, in the same manner as the cutout grooves
144
a
to
144
f
described above.
Each of the punch collets
120
a
to
120
f
has a leg
158
a
to
158
f
which abuts against the punch base
126
, a tapered section
160
a
to
160
f
which is inclined by a predetermined angle in a direction to make approach with respect to the axis of the mandrel
128
from the end of the leg
158
a
to
158
f
, a flat section
162
a
to
162
f
which extends in the upward direction from the tapered section
160
a
to
160
f
, and a curved section
164
a
to
164
f
which is continuous from the flat section
162
a
to
162
f
to a forward end surface
166
a
to
166
f
perpendicular to the axis of the mandrel
128
. A screw hole
168
a
to
168
f
is formed at a bottom surface of the leg
158
a
to
158
f
(see FIGS.
7
and
9
). The surface of the leg
158
a
to
158
f
, which is formed on the punch collet
120
a
to
120
f
, is highly accurately polished beforehand, in the same manner as the straight section
154
a
to
154
f
formed on the ridge
152
a
to
152
f.
A positioning pin
170
, which is used to center the punch base
126
and the mandrel
128
, is inserted between the inner circumferential surface of the recess
130
and the outer circumferential surface of the projection
142
(see FIGS.
7
and
9
). The axial centers of the punch base
126
and the mandrel
128
coincide with each other by the aid of the positioning pin
170
. The punch base
126
and the mandrel
128
are joined to one another by a fastening bolt
172
which is screwed into the first fastening hole
134
and the second fastening hole
146
.
A rod
174
a
to
174
f
penetrates through the inside of each of the holes
136
a
to
136
f
which are formed through the punch base
126
. The rod
174
a
to
174
f
is screwed into the screw hole
168
a
to
168
f
formed at the bottom surface of the punch collet
120
a
to
120
f
. A coil spring
176
a
to
176
f
, which is seated on the upper surface of the large diameter section
139
a
to
139
f
of the hole
136
a
to
136
f
and a flange
175
a
to
175
f
of the rod
174
a
to
174
f
, is wound around the rod
174
a
to
174
f.
As described above, the axes of the holes
136
a
to
136
f
and the sliding contact surfaces
148
a
to
148
f
are inclined at the same angle with respect to the axis of the punch base
126
and the mandrel
128
(axis of the main punch body
118
). Therefore, the rods
174
a
to
174
f
, the coil springs
176
a
to
176
f
, and the sliding contact surfaces
148
a
to
148
f
are inclined in parallel to one another in the same manner as described above (see FIGS.
7
and
8
).
The annular metal sleeve
122
, which has a pawl
122
a
at its lower end, is externally fitted to the punch base
126
, the straight sections
154
a
to
154
f
provided for the ridges
152
a
to
152
f
of the mandrel
128
, and the legs
158
a
to
158
f
provided for the punch collets
120
a
to
120
f
, in order to coaxially hold the main punch body
118
and the punch collets
120
a
to
120
f
(see FIGS.
7
and
8
). The pawl
122
a
of the metal sleeve
122
is placed on the placement section
132
formed for the punch base
126
, and the circumference thereof is held by the holder
124
.
The holder
124
has a pawl
178
which is disposed around the lower end, and it has an opening
180
having a large circular configuration which is disposed at its central portion. The pawl
178
is placed on the base pedestal
112
. The metal sleeve
122
and the main punch body
118
are positioned in the opening
180
. A plurality of bolt holes
184
a
to
184
f
, which are arranged at equal intervals, are bored through a top flat surface
182
of the holder
124
. Bolts
186
a
to
186
f
are allowed to penetrate through the bolt holes
184
a
to
184
f
to fix the holder
124
to the base pedestal
112
by means of screwing attachment (see FIG.
8
).
Next, explanation will be made for the function and effect of the forming machine constructed as described above.
At first, as shown in
FIG. 10
, the workpiece W is fitted to the forming punch
114
by the aid of a transport mechanism (not shown) so that the workpiece W is opposed to the first end
138
of the mandrel
128
of the main punch body
118
which constitutes the forming punch
114
. In this procedure, the inner circumferential surface of the workpiece W is coarsely machined beforehand so that the inner circumferential surface of the workpiece W is fitted to the forming sections
156
a
to
156
f
which are formed on the ridges
152
a
to
152
f
of the mandrel
128
and the curved sections
164
a
to
164
f
which are formed on the punch collets
120
a
to
120
f.
Subsequently, as shown in
FIG. 11
, the ironing die
16
is moved downwardly in the axial direction of the main punch body
118
in accordance with the action of the driving mechanism (not shown) while applying the pressing force to the outer circumferential surface of the workpiece W. Accordingly, a state is given, in which the workpiece W is interposed between the ironing die
16
and the forming sections
156
a
to
156
f
provided for the ridges
152
a
to
152
f
and the curved sections
164
a
to
164
f
provided for the punch collets
120
a
to
120
f
. The inner circumferential surface of the workpiece W is subjected to the plastic working to have a predetermined shape by the aid of the forming sections
156
a
to
156
f
. During this process, an undercut section W
1
is formed on the workpiece W so that the undercut section W
1
is coincident with the shape of the curved sections
164
a
to
164
f.
After the plastic working for the workpiece W is completed, the workpiece W is displaced vertically upwardly in accordance with the action of the transport mechanism (not shown). During this process, the undercut section W
1
, which is formed on the workpiece W as described above, allows the workpiece W to be fastened by the punch collets
120
a
to
120
f
. The punch collets
120
a
to
120
f
follow the workpiece W, and they make sliding movement in the upward direction on the sliding contact surfaces
148
a
to
148
f
integrally with the workpiece W.
In accordance with the sliding movement of the punch collets
120
a
to
120
f
on the sliding contact surfaces
148
a
to
148
f
, the rods
174
a
to
174
f
, which penetrate through the inside of the holes
136
a
to
136
f
formed through the punch base
126
, are moved upwardly in the holes
136
a
to
136
f
. Accordingly, the coil springs
176
a
to
176
f
, which are seated on the upper surfaces of the large diameter sections
139
a
to
139
f
of the holes
136
a
to
136
f
and the flanges
175
a
to
175
f
of the rods
174
a
to
174
f
, are contracted to increase the resilient force (see FIG.
12
).
The sliding contact surfaces
148
a
to
148
f
are formed so that they are inclined by the predetermined angle in the direction to make approach to the axis of the mandrel
128
. Therefore, as the punch collets
120
a
to
120
f
slide upwardly on the sliding contact surfaces
148
a
to
148
f
, the distances between the forward ends of the mutually opposing punch collets
120
a
to
120
f
are narrowed as a whole. As a result, when the workpiece W is displaced by a predetermined distance, a gap
194
is formed between the workpiece W and the punch collets
120
a
to
120
f
(see FIG.
12
). The workpiece W can be disengaged from the punch collets
120
a
to
120
f
with ease by utilizing the gap
194
.
The disengaged workpiece W is transported to the next step by the aid of the transport mechanism (not shown), to which a predetermined aftertreatment is applied.
Simultaneously with the disengagement of the workpiece W from the punch collets
120
a
to
120
f
, the punch collets
120
a
to
120
f
make sliding movement in the downward direction along the sliding contact surfaces
148
a
to
148
f
in accordance with the action of the resilient force of the coil springs
176
a
to
176
f
. The resilient force is applied to the punch collets
120
a
to
120
f
until the punch collets
120
a
to
120
f
are returned to the positions of the state before the workpiece W is fitted to the mandrel
128
for constructing the forming punch
114
.
In the embodiment of the present invention, the metal sleeve
122
is externally fitted to the punch base
126
, the straight sections
154
a
to
154
f
which are provided for the ridges
152
a
to
152
f
of the mandrel
128
, and the legs
158
a
to
158
f
provided for the punch collets
120
a
to
120
f
. Further, the positioning pin
170
is inserted between the inner circumferential surface of the recess
130
formed on the punch base
126
and the outer circumferential surface of the projection
142
formed on the mandrel
128
. Accordingly, the punch collets
120
a
to
120
f
are reliably maintained coaxially with the main punch body
118
. Further, the surfaces of the straight sections
154
a
to
154
f
and the legs
158
a
to
158
f
are highly accurately polished as described above. Therefore, it is possible to make the contact without providing any gap between the main punch body
118
and the punch collets
120
a
to
120
f
and the metal sleeve
122
.
Therefore, it is possible to suppress the occurrence of any axial deviation between the ironing die
16
and the main punch body
118
including the mandrel
128
to which the punch collets
120
a
to
120
f
are fitted as less as possible. Accordingly, when the pressing force is applied to the workpiece W by using the ironing die
16
, the pressing force can be applied to the workpiece W substantially uniformly. Therefore, it is possible to highly accurately perform the plastic working for the workpiece W. As a result, it is possible to easily machine the workpiece W in the aftertreatment steps.
As described above, the main punch body
118
is composed of the punch base
126
and the mandrel
128
. In this arrangement, the mandrel
128
, which is the portion for fitting the workpiece W thereto, is produced with a durable and expensive material so that the mandrel
128
may withstand the plastic working for the workpiece W to be repeatedly performed. However, according to the embodiment of the present invention, it is possible to reduce the production cost for the mandrel
128
by shortening the length of the mandrel
128
as short as possible. Consequently, it is possible to reduce the production cost for the forming machine
100
itself.
Further, the punch base
126
and the mandrel
128
can be easily separated from each other by loosening the bolts
186
a
to
186
f
to remove the forming punch
114
from the base pedestal
112
, disengaging the holder
124
and the metal sleeve
122
from the main punch body
118
, separating the rods
174
a
to
174
f
from the punch collets
120
a
to
120
f
, and loosening the fastening bolt
172
. For example, when the plastic working is performed for a workpiece W having a different shape, the punch collets are exchanged corresponding to the shape of the workpiece W every time when the plastic working is performed. It is necessary to exchange the punch collets
120
a
to
120
f
and the mandrel
128
together therewith in some cases. However, in the embodiment of the present invention, the forming machine
100
is constructed such that the punch collets
120
a
to
120
f
are detachable therefrom. Therefore, it is possible to conveniently exchange the punch collets
120
a
to
120
f
. Accordingly, the versatility of the forming machine
100
is improved, for example, such that it is possible to easily respond to the forming machining for a variety of workpieces.
As explained above, according to the present invention, it is possible to suppress the occurrence of the axial deviation between the ironing die and the forming punch as less as possible, and it is possible to substantially uniformly apply the pressing force to be applied to the workpiece by the ironing die. Therefore, it is possible to improve the accuracy of the plastic working for the workpiece. Further, after the plastic working for the workpiece is completed, the workpiece can be disengaged with ease. Therefore, it is unnecessary to use any complicated mechanism such as a cylinder mechanism for sliding the punch collets. Accordingly, the following specific effect is obtained. That is, the arrangement of the forming machine itself is simplified, and it is possible to realize the small size and the inexpensive price. Further, the forming step itself is quickened, because the resilient force of the coil springs is utilized to restore the punch collets to the original positions. Further, it is possible to produce the forming machine inexpensively, because the structure is simple. Furthermore, the versatility of the forming machine of this type is improved as well, for example, such that it is possible to respond to the machining for a variety of workpieces only by exchanging the punch collets to those which adapt to a shape of a new workpiece.
Claims
- 1. A forming machine comprising:an ironing die for applying pressing force to a workpiece; a forming punch having sliding contact surfaces formed obliquely with respect to an axis; and a plurality of punch collets capable of sliding on said sliding contact surface, said punch collets having straight sections with surfaces substantially parallel to said axis; wherein said forming punch further comprises: a main punch body having said sliding contact surfaces; a metal sleeve externally fitted to said main punch body and said punch collets, said metal sleeve having an inner surface externally fitted over said straight sections of said punch collets, said punch collects sliding along said inner surface in a direction substantially parallel to said axis; a holder for holding said metal sleeve; and elastic members accommodated in said holder; wherein said punch collets are forcibly restored to original positions along said sliding contact surfaces in accordance with resilient force of said elastic members when said ironing die is released from engagement with said workpiece.
- 2. The forming machine according to claim 1, wherein said elastic member is wound around a guide pin screwed and attached into said holder, and said elastic member is seated on an inner wall of said holder and a holding section of said punch collet.
- 3. The forming machine according to claim 2, wherein said guide pins, said elastic members, and said sliding contact surfaces are arranged obliquely with respect to an axis of said main punch body.
- 4. The forming machine according to claim 2, wherein said guide pin and said elastic member are arranged at the same angle of inclination as that of said sliding contact surface disposed closest there to.
- 5. The forming machine according to claim 3, wherein said guide pin and said elastic member are arranged at the same angle of inclination as that of said sliding contact surface disposed closest thereto.
- 6. A forming machine comprising:an ironing die for applying pressing force to a workpiece; a forming punch having sliding contact surfaces formed obliquely with respect to an axis; and a plurality of punch collets capable of sliding on said sliding contact surfaces, said punch collets having straight sections with surfaces substantially parallel to said axis; wherein said forming punch further comprises: a main punch body; a metal sleeve externally fitted to said main punch body and said punch collets, said metal sleeve having an inner surface externally fitted over said straight sections of said punch collets, said punch collects sliding along said inner surface in a direction parallel to said axis: and a holder for holding said metal sleeve; wherein said main punch body is composed of a punch base and a mandrel formed separately from said punch base; and said punch collet is slidable on said sliding contact surface formed on said mandrel, said punch collet also comprising an elastic member for pulling said punch collet toward said punch base.
- 7. The forming machine according to claim 6, wherein said punch base and said mandrel are integrally joined to one another by the aid of a fastening member.
- 8. The forming machine according to claim 6, wherein:a rod is attached to each of said plurality of punch collets; and said elastic member is wound around said rod to always pull said punch collet toward said punch base.
- 9. The forming machine according to claim 7, wherein:a rod is attached to each of said plurality of punch collets; and said elastic member is wound around said rod to always pull said punch collet toward said punch base.
- 10. The forming machine according to claim 8, wherein said sliding contact surfaces, said elastic members, and said rods are arranged obliquely at an equal angle with respect to an axis of said main punch body.
Priority Claims (2)
| Number |
Date |
Country |
Kind |
| 2000-029572 |
Feb 2000 |
JP |
|
| 2000-033236 |
Feb 2000 |
JP |
|
US Referenced Citations (3)
Foreign Referenced Citations (2)
| Number |
Date |
Country |
| Y2718448 |
May 1995 |
JP |
| B22729852 |
Dec 1997 |
JP |
