Work holders – With fluid means
Reexamination Certificate
2002-01-14
2004-07-06
Wilson, Lee D. (Department: 3723)
Work holders
With fluid means
C269S024000
Reexamination Certificate
active
06758467
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a clamp system which employs a plurality hydraulic clamps to removably secure a workpiece to a base plate. More specifically, the present invention relates to a main cylinder unit in each hydraulic clamp supplied through wall-based hydraulic pathways.
2. Description of the Related Art
Referring now to
FIG. 12
, standard clamp system includes a plurality of clamp devices
210
to secure a workpiece Wa to a base plate
200
. During operation, clamp devices
210
operate through hydraulic pressure to engage and disengage workpiece Wa. During normal engagement, workpiece Wa solidly engages base plate
200
for machining.
On a left-hand side of
FIG. 12
, a pair of bolts
217
secures a main cylinder unit
211
in an attachment hole
201
of base plate
200
. An output member
212
extends from main cylinder unit
211
and secures workpiece Wa to base plate
200
.
Output member
212
includes a piston rod
213
and an arm
214
. Piston rod
213
extends away from main cylinder unit
211
and base plate
200
. Arm
214
extends perpendicularly from main cylinder unit
211
and engages workpiece Wa. Arm
214
is pivotable about main cylinder unit
211
to allow easy positioning of workpiece Wa.
A guide
215
forms a rod-side cylinder end wall on main cylinder unit
211
and guides piston rod
213
during operation. A hydraulic pipe
216
joins a hydraulic hose (not shown) to main cylinder unit
211
.
During operation, hydraulic pipe
216
supplies hydraulic pressure from the hydraulic pressure supply device (not shown) to main cylinder unit
211
. As hydraulic pressure in main cylinder unit
211
increases, piston rod
213
lowers. As piston rod
213
lowers, arm
214
presses a clamping point (not shown) on workpiece Wa onto a receiving base
202
and base plate
200
.
On a right-hand side of
FIG. 12
, a pair of bolts
219
secures a second clamping device
210
to base plate
200
. A spacer base plate
218
spaces the right-hand side main cylinder unit
211
away from base plate
200
. During adjustment, replacement spacer base plates
218
may be used to adjust the clamping height ranges for differently shaped workpiece Wa.
Clamping devices
210
operate as horizontally pivoting clamps which allow arms
214
to pivot in a tandem with operation of piston rods
213
to allow easy placement of workpiece Wa. Unfortunately, clamping devices of this design have several undesirable features. First, hydraulic pipe
216
is easily damaged causing undesirably downtime and loss in production efficiency. Second, guide members
215
require a larger base plate
200
and reduce machining efficiency. Third, where hydraulic pipes
216
are damaged, clamping force may be unexpectedly reduced causing operator injury. Fourth, since each clamping device
210
requires an individual hydraulic pipe
216
complexity and costs are increased.
Referring now to
FIG. 13
, in a second clamp system, a main cylinder unit
221
of a clamp device
220
fits inside a base plate
230
. A flange
222
on clamp device
220
serves as a guide member and abuts an upper surface of base plate
230
.
A horizontal oil path
232
and a vertical oil path
231
link a hydraulic port
232
to a hydraulic pressure supply device (not shown). Horizontal oil path
232
and vertical oil path
231
are inside base plate
230
. Base plate
230
operates to protect horizontal and vertical oil paths
232
,
231
. Unfortunately, it is difficult to produce secure, clean, and effective internal oil passageways, thereby increasing manufacturing costs and reducing reliability.
Referring additionally to
FIG. 14
, in a third clamp system, a single spacer
225
spaces main cylinder unit
221
from a base plate
235
and accommodates differently shaped workpieces Wa.
Spacer
225
includes an oil path
226
. Oil path
226
joins hydraulic port
223
of main cylinder unit
221
to a hydraulic port
227
. Hydraulic port
227
is on a bottom end of oil path
226
and spacer
225
. A hydraulic pipe
236
extends from the hydraulic pressure supply device (not shown) to base plate
235
. A connected oil path
237
extends continuously from hydraulic pipe
236
to hydraulic port
223
. Connected oil path
237
supplies hydraulic pressure from the hydraulic pressure supply device to main cylinder unit
221
.
As noted above, with the above design it is difficult to produce secure, clean, and effective internal oil passageways, thereby increasing manufacturing costs and reducing reliability.
Referring additionally to
FIG. 15
, a fourth clamp system includes a pair of spacers
225
separating main cylinder unit
221
from a base plate
240
. Oil paths
226
in spacers
225
are aligned with a vertical oil path
241
. Oil path
241
and a horizontal oil path
242
transport hydraulic pressure from the hydraulic pressure supply device through oil paths
226
to main cylinder unit
221
.
In each clamp system described above, single or multiple spacers
218
,
225
adjust the height at which arms
214
of main cylinder units
220
clamp workpieces Wa. Unfortunately, each change in workpiece Wa size, requires disassembly, alignment of the multiple oil pathways, and secure reassembly. Such disassembly-alignment-reassembly actions increase production time, risk equipment damage, and increase the probability of hydraulic leaks.
As noted above, it is unfortunately also difficult to produce secure, clean, and effective internal oil passageways, thereby increasing manufacturing costs and reducing reliability.
Referring to
FIGS. 16 and 17
, a plurality of clamp devices
250
are disposed along an edge of a base plate
260
. A pair of hydraulic ports
252
,
253
are at a bottom end of a flange
251
on each clamp device
250
.
A plurality of clamping oil paths
261
supply hydraulic pressure from an external supply device (not shown) to each hydraulic port
252
on each respective clamp device
250
. Clamping oil paths
261
are inside base plate
260
.
A plurality of unclamping oil paths supply
265
return hydraulic pressure to the external supply device from each hydraulic port
253
of each respective clamp device
250
. Unclamping oil paths
265
are inside base plate
260
.
Shared oil paths
262
,
266
extend linearly inside base plate
260
a direction parallel to the plurality of clamping devices
250
. Clamping oil path
261
includes shared oil path
262
. Unclamping oil path
265
includes shared oil path
266
.
A plurality of horizontal oil paths
263
extends toward each respective clamp device
250
from shared oil path
262
. A plurality of horizontal oil paths
267
extends toward each respective clamp device
250
from shared oil path
266
.
A plurality of perpendicular oil paths
264
connects each oil path
263
to each respective hydraulic port ports
252
. A plurality of perpendicular oil paths
267
connects each oil path
267
to each respective hydraulic port
253
.
During operation it is desirable for base plate
260
to have both compact dimensions and sufficient strength and rigidity to secure workpieces Wa of a predetermined size. It is also desirable to maximize available work surface on each base plate
260
. By maximizing the available work surface and minimizing the dimensions of base plate
260
, multiple operations may be performed at a single work station. The more compact base plate
260
, the more compact a machining tool (restricted by the mounting zone of the base plate) may be for each workpiece Wa. Unfortunately, multiple hydraulic pipes reduce a base plate to workpiece ration and increase costs.
Unfortunately, with the design described above, production costs are high since clamping and unclamping oil paths
261
,
265
are difficult to produce. This difficulty in manufacture also increases production failure rates and reduces quality.
For each design described above, the plurality of hydraulic pipes restricts movement when transporting each respective base plate and increases production time.
Finally, when piston rods
213
extend th
Darby & Darby
Pascal Engineering Corporation
Wilson Lee D.
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