Note: Descriptions are shown in the official language in which they were submitted.
S P E C I F I C A T I O N
Title of the Invention:
Balancing Device for Press
Detailed Description of the Invention:
(Field of Industrial Application)
The present invention relates to a balancing device
for a press.
(Background and Problems of the Prior Art)
In presses of the type in which a slide moves up and
down with respect to a bolster, plural connections are
generally provided between the slide and a crankshaft,,
with clearance at the connections being shifted to one
side by the weight of the slide. Thus, when the press is
applied with an operational load, the clearance shifts to
the opposite side since the direction of load is opposite
to the direction of the weight, suspending the slide
temporarily. To prevent this so~called "pausing" phenom-
enon and to ensure smooth slide motions, the conventional
presses are usually equipped with slide balancers.
A slide balancer includes a balance cylinder which
is fixed to a frame and has a piston rod, which is connect-
ed to a slide so that the slide can be energi~ed upward
by the balance cylinder to achieve the aforementioned
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function. The slide balancer is, however, defective in
its durability as it is constantly under operation along
with the ascend/descend motions of the slide. Moreover,
as the press collects speed in operation, the slide is
also accelerated to such an extent that the balancer can
no longer follow the motion to become incapable of the
balancing function. Therefore, with high speed presses,
the slide balancers may possibly be omitted.
On the other hand, the die height clearance is
adjusted to accommodate changes in the height of metal
dies due to replacement, grinding, modification thereof.
Generally, a slide adjusting mechanism for die height
adjustment comprises a screw shaft connected to a crank- -
shaft via a connecting rod, a worm wheel rotatably supported
by a slide and screwed to said screw shaft, a worm gear
engaged with said worm wheel, and a motor to rotate said
worm gear. If the slide balancer is omi~ted in view of
the above, die height adjustment becomes very difficult
as the weight of the slide is directly applied on the
slide adjusting mechanism.
As a countermeasure, use of a larger sized motor
for the slide adjusting mechanism may be contemplated.
However, as a motor of this type is generally carried on
the slide, the weight of the slide will disadvantageously
increase further.
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(Object of the Invention)
Noting the fact that the balancing effect becomes
unnecessary as the asce~d/descend motions of the slide
collect speed as mentioned above, the present invention
aims to provide a balancing device for presses which is
capable of die height adjustment with simple operation
irrespective of the slide motions.
(Means to Solve the Problems and Opexational Effects)
To achieve the object, the present invention pro-
poses a means which is disconnected from the slide when
the slide is under operation and which energizes the load
of the slide upward during die height clearance adjust-
ment.
More particularly, the press of the type in which
a slide moves up and down relative to a bolster is charac-
terized in that an energizing means which is disconnected
from said slide when the slide is in ascend/descend
motions and which energizes the same upward when the die
height clearance is adjusted.
The present invention can provide a balancing device
for presses which is free from problems otherwise caused
by ascend/descend motions of the slide and which is
capabIe of die height clearance adjustment with simple
operation.
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Brief Description of the Drawings:
Fig. 1 shows a front view of a first embodiment of
the press according to the present invention.
Fig. 2 shows a sectional view of the cylinder
mechanism which energizes the slide upward in a second
embodiment of the present invention.
(Preferred Embodiments)
Referring to Fig. 1, a frame 1 comprises a bed 2,
columns 3 provided on both sides of said bed 2, and a
crown 4 suspended between said columns 3 at their upper
ends. A bolster 5 is provided on the upper surface of the
bed 2 so that a lower die (not shown) can be mounted
thereon. Further, a crankshaft 6 is rotatably supported
by said crown 4. On one side of the crankshaft 6 are
provided a clutch 7 and a fly wheel 8 totransmit rotation
from a motor ~not shown) to the crankshaft 6. A brake 9
is provided on the other side thereof.
A slide 12 is provided in a manner to freely movable
upward and downward between the columns 3, the slide bein~
connected to said crankshaft 6 via connecting rods 10 and
slide adjusting means 11. An energizing means 21 is
provided on each of the columns 3 at substantially center
thereof to energize the slide 12 upward when the die
height clearance is adjusted. At the lower surface of
the slide 12, an upper die (not shown) is attached.
. . .
The slide adjusting means 11 each comprises a screw
shaft 13 which is attached to the lower end of the
connecting rod 10 respectively, a worm wheel 14 which is
rotatably supported hy the slide 12 but is not movable in
the vertical direction and which is screwed to a screw
shaft 13, a worm gear 15 which is engaged with the worm
wheel 14, and a motor 16 which rotates the worm gear 15.
AS the motor 16 is driven, the worm wheels 14 are rotat-
ingly displaced along the screw shafts 13 in the axial
direction, whe~eby the height of the slide 12 is adjusted.
The worm gears 15 are mechanically~interlocked in the
structure.
The energizing means 21 each comprises a balance
cylinder 22 which energizes brackets 12a upward, the
bracket being projected from both sides of the slide 12,
a fluid pressure source 23 such as a compressor, a 4-port
electromagnetic switch valve 24 which selectively switches
the supply of compressed air from the source 23 between
an upper and a lower chambers of the balance cylinders 22.
The balance cylinders 22 are so positioned that the
upper ends of respective piston rods 22a will not inter-
fere with the brackets 12a of the slide 12 when the
compressed air from the fluid pressure source 23 is
supplied to the respective upper chambers of the balance
cylinders 22 by means of the 4-port electromagnetic switch
valve 24, or when the respective piston rods 22a recede
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downward (see the column on the right in Fig. 1). The
balance cylinders 22 are so positioned that the upper ends
of respective piston rods 22a will energize respective
brackets 12a of the slide 12 upward from the underneath
when the compressed air supply from the fluid pressure
source 23 is switched to the lower chambers of respective
balance cylinders, or when the piston rods 22a moves to
the uppermost end (see the column on the left in Fig. l).
Generally, when the clutch 7 is actuated and the
slide 12 repeats up and down motions, the piston rods 22a
of the respective balance cylinders 22 are set to stay at
the downmost position. Thus, the piston rods 22a and the
slide 12 do not interfere with each other even if the
slide 12 is moving up and down. As a result, the recip-
rocal motion of the slide 12 will not actuate the balance
cylinders thereby preventing heat otherwise generated in
the balance cylinders by the slide motions and the decrease
in the durability.
On the other hand, as the compressed air supply from
the fluid pressure source 23 is switched to the lower
chambers of the respective balance cylinders 22 by switch-
ing the 4-port electromagnetic switch valve 24, the piston
rods 22a of the respective balance cylinders 22 will move
upward to energize the brackets 12a of the slide 12
upward from the underneath to support the load of the
slide acting downwardly. As the motor 16 of the slide
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adjusting means 11 is driven, the worm wheels 14 are
rotatingly displaced smoothly along the screw shaft 22 in
the axial direction, the position o~ the slide 12 can be
easily adjusted.
Since the piston rods 22a of the respective balance
cylinders 22 are separated from the slide 12 when the slide
12 is moving up and down, heat generation and decrease in
durability can be prevented in the embodiment.
It is also noted that since the compressed air from
the pressure source 23 is supplied to respective balance
cylinders 22 via the 4-port electromagnetic switch valve
24 only when the die height clearance is adjusted, the
load on the balance cylinders 22 becomes static. This
leads to improved durability and safety as well as a
simpler construction.
The weight of the slide 12 can also be reduced since
it is not necessary to use a large sized motor 16 for the
slide adjusting means 11.
Fig. 2 shows the second embodiment of this invention
in which a piston rod 122a of a balance cylinder 122 is
attach d to the column 103 in a manner to face downward.
A cylindrical member 125 .i~ provided at the upper portion
of a slide 112. The piston rod 122a is inserted in the
cylindrical member 125 so that a flange 122b provided at
the tip of the rod engages with the upper inside wall 126
of the cylindrical member 125.
In this embodiment, as the compressed air is
supplied to an upper chamber of the balance cylinder
122, khe flange 122b of the piston rod 122a reaches an
intermediate position in the cylindrical member 125 of
the slide 122 so that the adjusting mechanism and the
slide become disconnected.
On the other hand, the compressed air is supplied to
tha lower chamber of the balance cylinder 122 to move the
piston rod 122a upward during the die height clearance
adjustment, whereby the flange 122b engages with the upper
inside wall 126 of the cylindrical~member 125 provided on
the slide 112 to energize upwardly the slide along with
the cylindrical member 125.
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