Metal deforming – By use of non-deforming work-gripping clamp and relatively... – Plural or complex apparatus
Reexamination Certificate
2001-03-14
2004-05-25
Crane, Daniel C. (Department: 3725)
Metal deforming
By use of non-deforming work-gripping clamp and relatively...
Plural or complex apparatus
C072S323000, C029S243580
Reexamination Certificate
active
06739168
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a hemming device and a hemming method for hemming a plate-like workpiece.
2. Description of Related Art
Conventionally, while the inner panel and the outer panel, for example, of a rear door which are the panel members of a vehicle are assembled with each other, hemming for hemming the peripheral edge of the outer panel and superposing the hemmed peripheral edge thereof on the peripheral edge of the inner panel is carried out by a hemming device shown in
FIG. 1
which is a side view of the hemming device and in
FIG. 2
which is a plan view thereof.
In this hemming device, a workpiece W is positioned and set on a hemi die
3
disposed on a base
1
in a state in which the outer panel
5
is provided below an inner panel
7
. The inner panel
7
is positioned and fixedly positioned on this upper position by a positioning jig
9
which is vertically moved by a cylinder
8
. The workpiece W thus positioned is provisionally hemmed by a plurality of pre-hemming punches
11
provided around the workpiece W and then finally hemmed by hemming punches
13
provided to correspond to the respective pre-hemming punches
11
.
The hemming punches
13
and the pre-hemming punches
11
are actuated by hydraulic cylinders
19
rotatably supported by brackets
15
fixed to the base
1
through rotation support shafts
17
, respectively. That is to say, if the hydraulic cylinder
19
is driven, the piston rode
21
of the cylinder
19
advances and a punch holder
23
having hemming punches
13
on a tip end thereof rotates about a rotation support shaft
27
in an arrow A direction relative to the bracket
25
on the base
1
, whereby the final hemming is carried out by the hemming punches
13
.
On the other hand, the pre-hemming punches
11
carry out provisional hemming prior to the hemming by the hemming punches
13
by advancing to the workpiece W by the rotational operation of the punch holder
23
in the arrow A direction and then retreat. That is to say, using one hydraulic cylinder
19
, the provisional hemming by the pre-hemming punches
11
and the final hemming by the hemming punches
13
are carried out in succession.
As for working units U
s
and U
c
each consisting of the hemming punch
13
, the pre-hemming punch
11
, the hydraulic cylinder
19
driving the respective punches and the like, a total of eight, i.e., four working units (U
s
) corresponding to the linear portion of a generally rectangular rear door and four working units (U
c
) corresponding to the corner portions of the rear door, are provided so as to hem the entire periphery of the workpiece W as shown in FIG.
2
.
SUMMARY OF THE INVENTION
However, the above-stated conventional hemming device has the following disadvantages:
(1) The hemming device is constituted to carry out hemming by the rotation of each punch holder
23
. Due to this, all of the eight working units cannot be actuated simultaneously so as to prevent adjacent working units from interfering with one another. Instead, it is necessary to use different operation timing among the respective working units such as, for example, to actuate the working units U
c
for corner portions prior to the working units U
s
for the linear portions. As a result, the cycle time of the working operation becomes disadvantageously longer.
(2) If the shape of the workpiece W is such that the vertical position of a region to be hemmed by one working unit changes along the peripheral edge portion in
FIG. 1
, the approach angles of the pre-hemming punches
11
with respect to the workpiece W become uneven. This makes provisional hemming accuracy unstable and degrades working quality.
(3) It is necessary to set the direction in which the hemming punch
13
applies hemming pressure to be perpendicular to the surface of the workpiece W and to appropriately set the approach angles of the pre-hemming punch
11
with respect to the workpiece W. Due to this, it is difficult to standardize hemming punches and the hemming punches should be set in accordance with the shape of each workpiece, thereby pushing up cost.
(4) To work a corner portion, a dedicated small working unit U
c
is required. The number of overall working units increases accordingly to thereby push up cost.
(5) The stroke of the hydraulic cylinder
19
tends to be long, which makes the overall working unit large in size. If the hydraulic cylinder
19
is disposed to be closer to the base
1
so as to shorten the stroke, then a driving force intensifies to thereby make the hydraulic cylinder
19
larger in size.
(6) The hemming device is constituted such that hemming pressure is generated by rotating the punch holder
23
by the hydraulic cylinder
19
attached to the base
1
through the bracket
15
and received on the base
1
side. This requires the rigidity of the base
1
and the overall working unit, making the overall working unit large in size.
Meanwhile, the conventional hemming device stated above employs the positioning jig
9
to position the inner panel
7
. Since this positioning jig
9
has a relatively long vertical stroke, the accuracy thereof deteriorates and the size is made large. Besides, it is necessary to provide a transport device dedicated to the transport of the workpiece such as a belt conveyer in addition to the positioning jig
9
so as to set the workpiece W on the hemming die
3
. This makes the entire facility large in size.
It is, therefore, an object of the present invention to suppress cost increase by decreasing the number of working units, preventing each working unit from becoming large in size, and to reduce processing time by allowing the respective working units to simultaneously operate without interfering with one another even if the units are adjacent each other.
It is also an object of the present invention to improve workpiece positioning accuracy, to dispense with a transport device dedicated to the transport of a workpiece and to thereby make entire facility small in size.
To obtain the above-stated objects, there is provided a hemming device comprising: a hemming punch provided on an upper portion of a C-shaped frame; a hemming die provided on a base on which the C-shaped frame is disposed, and vertically movable to be adjacent to and away from the hemming punch; and a driving section provided between said hemming die and a lower portion of the C-shaped frame and raising said hemming die to hem a workpiece set on said hemming die.
According to the hemming device thus constituted, by raising the hemming die using the driving section, the workpiece on the hemming die is hemmed between the hemming die and the hemming punch on the upper portion of the C-shaped frame.
Further, to obtain the above objects, there is provided a hemming method comprising: setting a workpiece on a hemming die vertically movably provided on a base in a state while a C-shaped frame and a pre-hemming punch provided at the C-shaped frame are retreated; advancing the C-shaped frame and the pre-hemming punch provided at the C-shaped frame; raising the hemming die by a driving section provided between a lower portion of the C-shaped frame and the hemming die, and conducting provisional hemming to the workpiece by the pre-hemming punch; retreating the pre-hemming punch; and raising the hemming die by the driving section, and conducting hemming to the workpiece by the hemming punch provided on an upper portion of the C-shaped frame.
According to the above-stated hemming method, by the raising operation of the hemming die by driving the driving section above the C-shaped frame, the workpiece is hemmed by the pre-hemming punch and the hemming punch provided on the C-shaped frame side.
Moreover, to obtain the above objects, there is provided a hemming device for hemming a peripheral edge of a workpiece using a lower die, on which the workpiece is set, and an upper die arranged above the lower die, the hemming device comprising: a hand mount provided on the lower die side; a workpiece grip hand positioning and gripping
Hario Hidehiko
Matsumoto Yasuyuki
Crane Daniel C.
McDermott & Will & Emery
Nissan Motor Co,. Ltd.
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