In a press brake relatively moving an upper table (5U) or a lower table (5L) upward and downward by a plurality of hydraulic cylinders (17L and 17R) so as to perform a bending work, the respective hydraulic cylinders (17L, 17R) are driven by individually controlling a pair of left and right two-way.
In a press brake relatively moving an upper table (5U) or a lower table (5L) upward and downward by a plurality of hydraulic cylinders (17L and 17R) so as to perform a bending work, the respective hydraulic cylinders (17L, 17R) are driven by individually controlling a pair of left and right two-way. fluid pumps and hydraulic devices (21L, 21R) provided in correspondence to the respective hydraulic cylinders (17L, 17R) The two-way fluid pumps and the respective hydraulic devices (21L, 21R) are mounted to a base plate (23) mounted to cylinder heads (18L, 18R) of the respective hydraulic cylinders (17L, 17R), and an oil tank (27) is provided in an upper side of the hydraulic devices (21L, 21R).
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1. A press brake comprising a plurality of hydraulic cylinders that move at least one of an upper table and a lower table relative to each other vertically, wherein respective individually controllable two-way fluid pumps that are provided in correspondence to the respective hydraulic cylinders are
1. A press brake comprising a plurality of hydraulic cylinders that move at least one of an upper table and a lower table relative to each other vertically, wherein respective individually controllable two-way fluid pumps that are provided in correspondence to the respective hydraulic cylinders are connected via individually controllable hydraulic devices.2. A press brake as claimed in claim 1, wherein the respective individually controllable hydraulic cylinders include an upper portion, the hydraulic devices connecting the respective two-way fluid pumps each include an upper side, a base plate is mounted to the upper portion of the respective hydraulic cylinders, the respective hydraulic devices are attached to the base plate, and an oil tank is provided in the upper side of the hydraulic devices.3. A press brake comprising a plurality of hydraulic cylinders for moving a ram vertically, the press brake comprising:a plurality of two-way fluid pumps respectively corresponding to the plurality of hydraulic cylinders and connected to upper cylinder chambers and lower cylinder chambers of the hydraulic cylinders; a servo motor that drives the respective two-way fluid pumps so as to supply a working fluid to at least one of the upper cylinder chambers and the lower cylinder chambers; a position detector that detects a vertical position of the ram; and a control device that controls the servo motor, the control device comprising: a determiner that determines whether a bending work has been finished based on a signal from the position detector; and an order unit that orders the servo motor to reverse rotate so as to reverse the two-way fluid pumps when the determiner determines that the bending work is finished. 4. A ram moving method in a press brake provided with a plurality of hydraulic cylinders, comprising:rotating two-way fluid pumps connected to upper cylinder chambers and lower cylinder chambers of the hydraulic cylinders, using a servo motor; supplying a working fluid to one of the upper cylinder chambers and the lower cylinder chambers in the respective hydraulic cylinders so as to move the ram vertically; detecting a vertical position of the ram so as to determine whether the bending work has been finished based on the detected ram position; and reversing the servo motor when it is determined that the bending work is finished, thereby reversing the two-way fluid pump so as to supply the working fluid supplied to the one cylinder chamber to another cylinder chamber and thereby move the ram vertically. 5. A press brake comprising:a frame; a first table freely moving vertically; a second table moving relative to the first table so as to approach to and separate from the first table; a left hydraulic cylinder provided in a left side of the frame to move the first table vertically; a first two-way fluid pump connected to an upper cylinder chamber and a lower cylinder chamber of the left hydraulic cylinder, the first two-way fluid pump discharging a working fluid in a normal flow direction and a reverse flow direction to operate the left hydraulic cylinder in a vertical direction; a first servo motor that rotates the first two-way fluid pump in a normal rotation direction and a reverse rotation direction; a first control apparatus that controls the first servo motor; a right hydraulic cylinder provided in a right side of the frame to move the first table vertically; a second two-way fluid pump connected to an upper cylinder chamber and a lower cylinder chamber of the right hydraulic cylinder, the second two-way fluid pump discharging the working fluid in the normal flow direction and the reverse flow direction to operate the right hydraulic cylinder in the vertical direction; a second servo motor that rotates the second two-way fluid pump in the normal rotation direction and the reverse rotation direction; and a second control apparatus that controls the second servo motor independently of the first servo motor. 6. A press brake as claimed in claim 5, further comprising:a first position detector that measures a position with respect to the second table at a left side of the first table; and a second position detector that measures a position with respect to the second table at a right side of the first table, wherein the first control apparatus is provided with a determiner that determines whether a bending work is finished based on a signal from the first position detector, and an order unit that orders the first servo motor to reverse rotate so as to reverse the first two-way fluid pump when the determiner determines that the bending work is finished; and wherein the second control apparatus is provided with a determiner that determines whether the bending work has been finished based on a signal from the second position detector, and an order unit that orders the second servo motor to reverse rotate so as to reverse the second two-way fluid pump when the determiner determines that the bending work has been finished. 7. A press brake as claimed in claim 6, wherein the first two-way fluid pump is connected to the left hydraulic cylinder via a first hydraulic device;the second two-way fluid pump is connected to the right hydraulic cylinder via a second hydraulic device; the first hydraulic device and the first two-way fluid pump are located in the left hydraulic cylinder; and the second hydraulic device and the second two-way fluid pump are located in the right hydraulic cylinder. 8. A ram moving method in a press brake comprising:rotating a first two-way fluid pump that is connected to an upper cylinder chamber and a lower cylinder chamber of a left hydraulic cylinder, using a first servo motor; supplying a working fluid to one of the upper cylinder chamber and the lower cylinder chamber in the left hydraulic cylinder so as to move a first table towards a second table; detecting a vertical position of the first table with respect to the second table, using a first position detector; determining whether a bending work is finished based on a position of the first table detected by a first control apparatus; supplying the working fluid supplied to the one cylinder chamber in the left hydraulic cylinder to another cylinder chamber and thereby moving a left portion of the first table further from the second table, in accordance with the first control apparatus reverse rotating the first servo motor to thereby reverse the first two-way fluid pump, when it is determined that the bending work has been finished; rotating a second two-way fluid pump that is connected to an upper cylinder chamber and a lower cylinder chamber of a right hydraulic cylinder, using a second servo motor; supplying the working fluid to one of the upper cylinder chamber and the lower cylinder chamber in the right hydraulic cylinder so as to move the first table towards the second table; detecting the vertical position of the first table with respect to the second table, using a second position detector; determining whether the bending work has been finished, based on a position of the first table detected by a second control apparatus; and supplying the working fluid supplied to the one cylinder chamber in the right hydraulic cylinder to another cylinder chamber and thereby moving a right portion of the first table further from the second table, in accordance with the second control apparatus reverse rotating the second servo motor to thereby reverse rotate the second two-way fluid pump, when it is determined that the bending work has been finished, wherein the first control apparatus and the second control apparatus respectively control the first servo motor and the second servo motor in an independent manner. 9. A press brake as claimed in claim 1, wherein the respective individually controllable hydraulic cylinders include an upper portion, the hydraulic devices connecting the respective two-way fluid pumps each include an upper side, and a base plate is mounted to the upper portion of the respective hydraulic cylinders, the respective hydraulic devices are attached to the base plate, and an oil tank is provided in the upper side of the hydraulic devices.10. A press brake as claimed in claim 1, further comprising:a crowning cylinder provided in a center portion of the lower table so as to facilitate vertical positioning of a die that is provided in an upper end portion of the lower table; and a two-way fluid pump configured so as to be connected via a hydraulic device in correspondence to the crowning cylinder.
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이 특허에 인용된 특허 (8)
Dressing Paul A. (Cincinnati OH) Macdonald John L. (Aurora IN), Apparatus for synchronizing cylinder position in a multiple cylinder hydraulic press brake.
Otremba Carsten (Esslingen DEX) Schaich Guenther (Kirchheim-Teck DEX) Beyer Joachim (Ravensburg DEX), Method for controlling the drive for a hydraulic press having a plurality of operating phases.
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