Cutting – Tool or tool with support – Cutting couple type
Reexamination Certificate
1999-09-22
2002-06-25
Peterson, Kenneth E. (Department: 3724)
Cutting
Tool or tool with support
Cutting couple type
C083S698910
Reexamination Certificate
active
06408728
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a punching apparatus for stamping and a method for producing the same for applying perforating machining to a sheet-shaped workpiece.
2. Description of the Related Art
The punching apparatus for stamping has been hitherto used for defining a plurality of holes through a sheet-shaped workpiece by means of stamping machining. Such a punching apparatus for stamping is constructed as follows. That is, a plurality of lengthy holes
1003
are defined through a metal plate or the like by means of electric discharge machining (see FIG.
14
A). The holes are precisely finished by means of wire electric discharge machining to produce a punch holder
1002
(see FIG.
14
B).
As shown in
FIG. 15
, lengthy punch members
1004
having a substantially rectangular cross section are inserted into the holes
1003
which are defined through the punch holder
1002
as described above. Roots of the punch members
1004
are secured to the punch holder
1002
by using, for example, an adhesive.
The punch members
1004
are slidably inserted into lengthy holes
1006
of a stripper
1005
which is provided for the punching apparatus for stamping. Further, the punch members
1004
are inserted into lengthy holes
1008
which are defined through a die
1007
.
When a plurality of lengthy holes
1011
are bored through a workpiece
1009
such as a green sheet by using the stamping punching apparatus
1001
constructed as described above, the workpiece
1009
is placed on the die
1007
. When the punch members
1004
and the stripper
1005
are moved downwardly, the lower surface of the stripper
1005
firstly abuts against the upper surface of the workpiece
1009
. Subsequently, the punch members
1004
are moved downwardly to apply the perforating machining to the workpiece
1009
.
However, in the case of the conventional stamping punching apparatus
1001
as described above, it is necessary that the hole
1003
is formed to be slightly larger than the dimension of the punch member
1004
in order to insert the punch member
1004
into the hole
1003
. For this reason, a slight gap A is generated between the punch member
1004
and the wall for forming the hole
1003
of the punch holder
1002
. Therefore, it is difficult to improve the positional accuracy of the respective punch members
1004
.
On the other hand, the holes
1006
defined through the stripper
1005
are also formed to be slightly larger than the rectangular dimension of the punch member
1004
. For this reason, a gap B exists between the punch member
1004
and the wall of the hole
1006
. As a result, the error in positional accuracy of the punch member
1004
is allowable within a range of the gap B. Therefore, a problem arises in that the positional accuracy and the shape accuracy are lowered for the hole
1011
of the workpiece
1009
subjected to the perforating machining performed by the stamping punching apparatus
1001
. Further, any unbalanced load is exerted on the stripper
1005
through which the punch member
1004
is inserted. It is feared that the punch member
1004
and the stripper
1005
may be broken.
The hole
1008
of the die
1007
is formed to be larger than the rectangular dimension of the punch member
1004
so that the punch member
1004
is reliably inserted therethrough even when any error exists in the rectangular dimension of the punch member
1004
or in the position of the punch member
1004
with respect to the punch holder
1002
. When the pitch between the punch members
1004
is small, the gap between the hole
1008
and the adjoining hole
1008
is narrow. Therefore, the following problem arises. That is, if there is any difference in size between the gaps C
1
and C
2
generated between the punch member
1004
and the walls for forming the hole
1008
of the die
1007
, any inclination (deformation in the right or left direction in
FIG. 15
) is caused by the gap A in the non-punched portion D of the workpiece
1009
, resulting in defect in shape.
Although the respective punch members
1004
are formed to be lengthy in the vertical direction in
FIG. 15
, their first ends are merely supported by the punch holder
1002
. Therefore, it is feared that the punch member
1004
may be deformed by the load exerted on the punch member
1004
during the stamping, or the punch member
1004
is broken due to the buckling.
When the punch member
1004
is exchanged due to any breakage or the like, it is necessary to perform the operation to scrape the cured adhesive by using a grinder or the like. However, during this operation, when the pitch for the punch members
1004
is small, for example, when the punch members
1004
are arranged at a pitch of not more than 0.6 mm, then the following inconvenience appears. That is, for example, a highly sophisticated technique is required for the operation to detach and attach only the punch member
1004
which is required to be exchanged. Further, it is complicated to perform the operation to insert all of the punch members
1004
into the holes
1006
of the stripper
1005
again.
SUMMARY OF THE INVENTION
The present invention has been made in order to dissolve the various problems described above, an object of which is to provide a punching apparatus for stamping and a method for producing the same in which the positional accuracy and the shape accuracy of the hole defined through a workpiece are improved by improving the positional accuracy of a punch member, the rigidity of the punch member can be improved, a stripper is prevented from application of any unbalanced load, and the punch member can be easily exchanged.
According to the present invention, there is provided a punching apparatus for stamping for applying perforating machining to a workpiece by using punch members, the apparatus comprising a punch holder secured to an upper die; a die member secured to a lower die; a plurality of grip members detachably fastened to the punch holder; and the plurality of punch members formed on each of the plurality of grip members.
Accordingly, it is unnecessary to individually assemble the punch members to the punch holder one by one, and hence there is no assembling error. Therefore, the positional accuracy of the punch member is improved, and the positional accuracy and the shape accuracy can be improved for the hole to be defined through the workpiece. Further, for example, even when the punch member has a slender pin-shaped configuration, it is possible to reduce the occurrence of fracture and breakage, because its rigidity is enhanced, which is preferred.
It is preferable for the punching apparatus for stamping according to the present invention that the grip member and the punch members are formed in an integrated manner by using a single material.
Accordingly, it is unnecessary to separately produce the grip member and the punch members so that they are assembled to one another. Therefore, the production steps are simplified, and any defect does not occur in positional accuracy of the punch member upon assembling. It is possible to further enhance the rigidity of the punch member.
It is preferable for the punching apparatus for stamping according to the present invention that the grip member has a rectangular cross section, and a plurality of grooves are formed on at least two opposing side walls of the rectangular cross section; and the punch holder is defined with a hole having a rectangular cross section corresponding to the grip member, and the grip member is fitted to the punch holder with a gap such that crosspieces formed between the grooves on the side walls of the grip member slidably contact with side walls of the hole of the punch holder. In this arrangement, it is more preferable that the crosspiece on the side wall of the grip member is formed to have a circular arc-shaped configuration. It is also preferable that the crosspiece involves a circular arc-shaped configuration with its top formed to be flat.
Accordingly, when the grip member integrally provided with the p
Kabe Shusaku
Kitamura Kazumasa
Matsubayashi Satoshi
Noritake Motoo
Tsuji Hiroyuki
Burr & Brown
NGK Insulators Ltd.
Peterson Kenneth E.
LandOfFree
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