JPH10211522A - Method for correcting deflection of table in bending machine and device therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for correcting deflection of a table in a bending machine with which proper crowning pressure is controlled even when the change of flow rate of a pressure oil and surge pressure or the like are generated. SOLUTION: To correct the deflection of the lower table 5 or upper table which are generated at the time of bending the metal plate W by corporation of a punch P with a die D, the volume of the pressure oil which is supplied to a cylinder 11 for correcting deflection is adjusted by controlling a proportional valve with a controller 15, but, at this time, the flow rate of the pressure oil which is supplied to the cylinder 11 for correcting deflection or the flow rate of the pressure oil which is discharged from the cylinder 11 for correcting deflection is suppressed not more than a specified volume with a flow control valve 37.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and a device for correcting a bending of a table in a bending machine, and more particularly to a bending machine for correcting a bending of a table of a large bending machine using a hydraulic cylinder. The present invention relates to a method for correcting a table deflection and an apparatus therefor.

[0002]

2. Description of the Related Art FIG. 6 shows an outline of a very common press brake 1 which has been conventionally known. The press brake 1 is a bending machine that raises and lowers a lower table 5 on which a die D is mounted by a processing cylinder 3 and that bends a plate material W in cooperation with an upper table 7 on which a punch P is mounted. Since the configuration of the press brake 1 is already known, a detailed description is omitted.

In FIG. 6, as a table deflection correcting device 9 in the press brake 1, a deflection correcting device for correcting the amount of deflection of the lower table 5 when a plate material W is bent by a plurality of deflection correcting cylinders 11 is used. (Crowning mechanism) is known. In the bending correction device 9 for the table, the bending correction cylinder 11 is controlled in proportion to the bending pressure, so that the bending of the lower table 5 suitable for bending the plate material W can be performed. .

Here, the deflection correction amount d of the lower table 5
Is determined from the relationship between the proportionality constant α and the bending pressure p that are adjusted to the bending conditions. That is, d = α × p. Since the deflection correction amount d of the lower table 5 is proportional to the crowning pressure, appropriate deflection correction can be performed by the deflection correction cylinder 11.

That is, referring to FIG.
For example, a pair of left and right bending cylinders 3 for raising and lowering the lower table 5 on which the die D is mounted and bending the plate material W is a pressure sensor P.
The bending pressure is detected by G and fed back to the control device 15 via the A / D board 13. The controller 15 calculates the required pressure of the deflection correction cylinder 11 from the feedback pressure.

On the other hand, the lower table 5 is provided with a plurality of (two in this case) deflection correction cylinders 11.
The deflection correction cylinder 11 is controlled by the controller 15
/ A board 17 and a proportional valve 23 having a spool 21 controlled via an amplifier 19.

The proportional valve 23 is connected to the pump 25 and the tank T. The proportional valve 23 is recovered to the tank T via the proportional valve 23 and the flow rate of the pressure oil supplied to the deflection correction cylinder 11 by the movement of the spool 21. The pressure sensor PG constantly detects the pressure of the deflection correction cylinder 11 by the pressure sensor PG and feeds it back to the control device 15, so that the deflection correction cylinder 11 calculated by the control device 15 is obtained. Is controlled to obtain the required pressure.

FIG. 8 shows a hydraulic circuit 27. 8, the proportional valve 23 includes a spool 21 for adjusting the opening degree of the flow path 29, a solenoid 31 for pushing the spool 21 to the flow path 29, and a spool 21 when the solenoid 31 is off. Spring 3 biasing leftward in FIG.
Three.

Therefore, when the command value from the control device 15 is zero, the spool 21 is pushed leftward in FIG. 8 by the return force of the spring 33, so that the pressure oil from the pump 25 is drained to the tank T. (Arrow in FIG. 8).

When the deflection correcting cylinder 11 is raised, the opening of the flow passage 29 is reduced by moving the spool 21 to the right in FIG. Accordingly, the pressure oil from the pump 25 is supplied to the deflection correction cylinder 11 side, so that the pressure of the deflection correction cylinder 11 increases.

Since the pressure of the deflection correction cylinder 11 is monitored by the pressure sensor PG, when the pressure of the deflection correction cylinder 11 becomes higher than the required pressure, the solenoid 29 is moved to the left in FIG. The controller 15 controls so as to obtain a predetermined pressure by increasing the opening degree of the flow path 29 and decreasing the pressure, and corrects the lower table 5 appropriately.

[0012]

Generally, the discharge amount Q of the pressure oil discharged from the pump 25 is determined by the area of the deflection correction cylinder 11 and the response speed. Therefore,
In the case of a small press brake 1 having a small bending pressure, the discharge amount Q of the pump 25 may be small because the area of the deflection correction cylinder 11 can be small, but the press brake 1 is large and long. In some cases, the deflection correction cylinder 11 may be large or a plurality of deflection correction cylinders 11 may be used. Therefore, the discharge amount Q of the pump 25 increases,
The flow rate of the pressure oil flowing through the flow path 29 of the proportional valve 23 also increases.

In the large press brake 1, the rigidity of the upper and lower tables 7, 5 is often increased in order to reduce the amount of deflection of the upper and lower tables 7, 5. In such a press brake 1, when the pressure of the deflection correction cylinder 11 is lowered, the flow of the pressure oil in the deflection correction cylinder 11 changes rapidly because the reaction force of the upper and lower tables 7, 5 is large. Since the kinetic energy of the fluid is changed to pressure energy, a surge pressure is generated.

Such a change in the flow rate passing through the proportional valve 23 and the generation of surge pressure make it difficult to control the proportional valve 23.
As shown in FIG. 9, there is a problem that noise is generated as vibration of the spool 21 and vibration of the hydraulic circuit system.

Further, since an appropriate crowning force is not generated due to the vibration of the pressure of the deflection correction cylinder 11, the upper table 7 or the lower table 5 is not corrected properly, and the bending accuracy is deviated and the bending process is performed with high accuracy. There is a problem that can not be.

An object of the present invention is to pay attention to the above-described conventional technology, and to control an appropriate crowning pressure even if a sudden change in the flow rate of pressure oil or a surge pressure occurs. It is an object of the present invention to provide a method and an apparatus for correcting a bending of a table in a bending machine capable of performing the method.

[0017]

In order to achieve the above object, a method for correcting the deflection of a table in a bending machine according to the present invention is characterized in that one of an upper table equipped with a punch and a lower table equipped with a die is provided. The plate is bent in cooperation with the punch and die by raising and lowering, and a proportional valve that adjusts the pressing force generated in the deflection correction cylinder provided on the upper table or the lower table is controlled by the control device. A bending machine for correcting the deflection of the upper table or the lower table accompanying the bending, wherein the flow rate of the pressure oil supplied to the deflection correction cylinder and the flow rate of the drain oil discharged from the deflection correction cylinder Is suppressed to a certain amount or less.

Therefore, in order to correct the deflection of the lower table or the upper table caused when the plate material is bent by cooperation of the punch and the die, the control device controls the proportional valve to supply the deflection to the deflection correcting cylinder. At this time, the flow rate of the pressure oil supplied to the deflection correction cylinder or the flow rate of the pressure oil discharged from the deflection correction cylinder is suppressed to a certain amount or less.

A bending correction device for a table in a bending machine according to a second aspect of the present invention is characterized in that one of an upper table on which a punch is mounted and a lower table on which a die is mounted are moved up and down to cooperate with the punch and the die to form a plate. The bending of the upper table or the lower table accompanying the bending is performed by controlling a proportional valve that adjusts the pressing force generated in the deflection correcting cylinder provided on the upper table or the lower table by performing the bending. A flow control valve for suppressing the flow rate of pressure oil supplied to the deflection correction cylinder and the flow rate of drainage oil discharged from the deflection correction cylinder to a predetermined flow rate or less.
It is characterized by being provided.

Therefore, in order to correct the deflection of the lower table or the upper table caused when the plate material is bent by cooperation of the punch and the die, the controller controls the proportional valve to supply the deflection to the deflection correction cylinder. At this time, the flow rate of the pressure oil supplied to the deflection correction cylinder or the flow rate of the drain oil discharged from the deflection correction cylinder is suppressed to a certain amount or less by the flow control valve.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows a deflection correcting device 35 for a table in a bending machine according to the present invention. The press brake 1 to which the deflection correcting device 35 of this table is applied is a very common one, and has already been described in the section of the prior art. Will be denoted by the reference numeral.

Referring also to FIG. 2, in the deflection correcting device 35 of this table, a flow control valve 37 is provided between the deflection correcting cylinder 11 and the hydraulic pump 25, and the hydraulic fluid flowing through the flow passage 29 is provided. This prevents sudden changes in the flow rate.

Referring to FIG. 4, there is shown a case where the solenoid 31 is off (in FIG. 3). In this case, the spool 21 is pressed against the solenoid by the spring 33, and the flow path 29 is in an open state. The pressure oil from the pump 25 is drained to the tank T and the deflection correction cylinder 11
Is not supplied to the lower table 5, so that the lower table 5 is not corrected.

On the other hand, FIG. 5 shows a state of the lower table 5 at the start of the deflection correction (FIG. 3). In this state, the solenoid 31 moves the spool 21 rightward in FIG. 2 by a command from the control device 15 to narrow the flow path 29, so that the pressure oil from the pump 25 is supplied to the deflection correction cylinder 11. Then, the correction of the deflection of the lower table 5 is started (in FIG. 3).

Normally, in the pressurized state for deflection correction, the pressure is constantly monitored by the pressure sensor PG and the pressure is fed back to the control device 15, so that the pressure of the deflection correction cylinder 11 becomes higher than the command pressure. BA (H in FIG. 3)
Point), the control device 15 controls the proportional valve 23 to
1 is moved to increase the opening degree of the flow path 29, and conversely, if the pressure of the deflection correction cylinder 11 becomes lower than the command pressure (point L in FIG. 3), the spool 21 is moved to open the flow path 29. By reducing the degree, the pressure of the deflection correction cylinder 11 converges to the command value (A in FIG. 3).
point).

As described above, even in the case of the large press brake 1, the amplitude B of the vibration can be reduced by providing the flow control valve 37 to prevent a rapid change in the flow rate of the pressure oil. Even if the discharge amount Q of the pump 25 increases or the flow of the pressure oil changes suddenly and a surge pressure occurs, the pressure of the deflection correction cylinder 11 converges to the command value as in the normal case. (See FIG. 3). Thereby, the deflection of the lower table 5 is properly corrected, so that a highly accurate bending process can be performed.

The present invention is not limited to the above-described embodiment, but can be implemented in other modes by making appropriate changes.

[0029]

As described above, according to the method for correcting the bending of a table in a bending machine according to the first aspect of the present invention, a lower table or an upper table generated when a plate is bent by cooperation of a punch and a die. In order to correct the deflection, the control device controls the proportional valve to adjust the amount of the pressure oil supplied to the deflection correction cylinder, but at this time, the flow rate or the deflection correction of the pressure oil supplied to the deflection correction cylinder is performed. The flow rate of pressurized oil discharged from the cylinder is kept below a certain level, so that even in a large bending machine, the sudden increase in the flow rate of pressurized oil and the occurrence of surge pressure can be suppressed, and the value specified by the control device can be reduced. It can be converged. This enables high-precision bending.

In the bending correction device for the table in the bending machine according to the second aspect of the present invention, in order to correct the bending of the lower table or the upper table which occurs when bending the plate material by cooperation of the punch and the die, The controller controls the proportional valve to adjust the amount of pressure oil supplied to the deflection correction cylinder. At this time, the flow rate of the pressure oil supplied to the deflection correction cylinder or the drainage oil discharged from the deflection correction cylinder Flow control valve to keep the flow rate below a certain level, so even in a large bending machine, it is possible to suppress the sudden increase in the flow rate of hydraulic oil and the occurrence of surge pressure, and to converge to the value commanded by the control device. it can. This enables high-precision bending.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a deflection correcting device for a table in a bending machine according to the present invention.

FIG. 2 is an enlarged view showing a hydraulic circuit in FIG.

FIG. 3 is a graph showing a pressure of a deflection correction cylinder.

FIG. 4 is an explanatory diagram showing a state of a hydraulic circuit when a solenoid is off.

FIG. 5 is an explanatory diagram showing a state of a hydraulic circuit at the start of deflection correction of a lower table.

FIG. 6 is an explanatory view showing a conventional press brake.

FIG. 7 is a block diagram showing a conventional table deflection correcting apparatus.

FIG. 8 is an enlarged view showing a hydraulic circuit in FIG. 7;

FIG. 9 is a graph showing a pressure of a deflection correction cylinder.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Press brake (bending machine) 5 Lower table 7 Upper table 11 Cylinder for deflection correction 15 Control device 23 Proportional valve 35 Deflection correction device for table 37 Flow control valve P Punch D Die

Claims (2)

[Claims] 1. A sheet material is bent in cooperation with a punch and a die by raising and lowering one of an upper table on which a punch is mounted and a lower table on which a die is mounted.
A bending machine that controls a proportional valve that adjusts a pressing force generated in a deflection correction cylinder provided on an upper table or a lower table by a control device, and corrects deflection of the upper table or the lower table accompanying bending. Wherein the flow rate of the pressure oil supplied to the deflection correction cylinder and the flow rate of the drain oil discharged from the deflection correction cylinder are suppressed to a certain value or less. Method. 2. A plate material is bent in cooperation with a punch and a die by raising and lowering one of an upper table on which a punch is mounted and a lower table on which a die is mounted.
A bending machine that controls a proportional valve that adjusts a pressing force generated in a deflection correction cylinder provided on an upper table or a lower table by a control device, and corrects deflection of the upper table or the lower table accompanying bending. And a flow control valve for suppressing a flow rate of pressure oil supplied to the deflection correction cylinder and a flow rate of drainage oil discharged from the deflection correction cylinder to a predetermined flow rate or less. A table deflection correction device for a processing machine.