JPH05337554A - Device for correcting half-releasing for press brake - Google Patents

Abstract

PURPOSE:To obtain a uniform bending angle over the entire length of a workpiece by calculating deflection quantity by fetching the detection output of a deformation sensor for an upper beam and a lower beam and controlling the driving of a plural actuator so that the deflection quantity goes to an optimum value. CONSTITUTION:The detection outputs of all deformation sensors SU1 to SUn, SD1 to SDn are successively fetched by an NC device, and the deflection quantities of the upper beam 4 and the lower beam 5 are calculated from the detection output. Also, by comparing the deflection quantity of the upper beam 4 with that of the lower beam 5, whether or not the deflection quantity is optimum is decided. When the deflection quantity is not optimum, a command signal for a control valve is successively corrected by an NC device and each of hydraulic cylinders ACT1 to ACTn is successively corrected. Again, the detection outputs of the deformation sensors SU1 to SUn, SD1 to SDn are successively fetched the deflection quantity is calculated, and the comparison is made to decide whether the quantity is optimum or not. The operation is repeated until the deflection quantity is optimum.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention corrects a center opening phenomenon caused by bending of a lower beam and an upper beam during bending by a press brake so that a uniform bending angle can be obtained over the entire length of a work. The present invention relates to a correction device for a medium opening.

[0002]

2. Description of the Related Art When a plate work is bent by a press brake, a die 1 having a V groove and a punch 2 are attached to the press brake as shown in FIG. The pressing force is applied to the work 3. In this case, the upper beam (upper beam) of the press brake is applied by the load for bending the work.
4 is upward, and lower beam (lower beam) 5 is downward, as shown by the phantom line (-dotted line) in FIG. 6, and as a result, as shown in FIG. A so-called loose opening phenomenon occurs in which the bending angle θ2 becomes larger than the bending angles θ1 at both ends.

Conventionally, there are those that use wedges or hydraulic cylinders to correct this middle opening.

As a method using a wedge, Japanese Patent Publication No. 60
-47017 and JP-A-62-224426. That is, in these wedge methods, a plurality of wedges are interposed between the die and the lower beam, and the wedges are appropriately tilted in the vertical direction in accordance with the desired curved shape of the die so that the central portion of the die is moved upward. It is designed to be curved (crowning).

The hydraulic cylinder system has a Japanese Patent Publication No.
There are Japanese Patent Publication No. 5464 and Japanese Patent Publication No. 52-22911. In Japanese Patent Publication No. 52-5464, a cylinder that expands and contracts along the bending length direction is provided in the lower beam, and when the punch is pressed, the cylinder is actuated to pull inside the left and right portions of the lower beam. The center of the die is curved upward.

In Japanese Patent Publication No. 52-22911, a long gap is provided near the press face of the upper beam along the direction of the press face, a large number of deflection cylinders are provided in the gap, and a plurality of these deflection cylinders are used. The bending of the frame is corrected.

[0007]

However, in any method using these wedges or hydraulic cylinders, it is necessary to detect the state quantity at each position in the longitudinal direction of the upper and lower molds (punch and die) in order to detect the crowning amount and the cylinder. Finding the optimum pressure conditions becomes difficult.

The present invention has been made in view of such a situation, and by bending the lower beam or the upper beam under the optimum condition, V bending is performed with an even load to make a uniform bending angle over the entire length of the work. An object of the present invention is to provide a press brake middle opening correction device that is obtained.

[0009]

According to the present invention, there is provided a press brake for bending a work between the punch and the die by moving a punch attached to the upper beam and a die attached to the lower beam into contact with each other. A plurality of upper beam strain sensors provided along the longitudinal direction of the beam to detect the deflection of the upper beam, and a plurality of lower sensors provided along the longitudinal direction of the lower beam to detect the deflection of the lower beam. Distortion sensors for the beam and distributed between the lower beam and the lower mold or between the upper beam and the upper mold along the direction of the bending line, and are arranged vertically in the lower mold or the upper mold. A plurality of actuators that apply a pressing force, and the lowering of the upper beam is stopped in the middle of the start of pressurization to the completion of pressurization. Sensor and the detection output of the lower beam strain sensor, the deflection amounts of the upper beam and the lower beam are calculated based on these detection outputs, and the deflection amounts of the upper beam and the lower beam are adjusted to appropriate values based on the calculated values. And a control means for controlling the drive of the plurality of actuators and then for restarting the pressurization control.

[0010]

According to the present invention, the lowering of the upper beam is stopped on the way from the start of pressurization to the completion of pressurization, and the distortion amounts of the lower beam and the upper beam are detected in this stopped state,
According to the detection value, a plurality of dispersedly arranged along the direction of the bending line between the lower beam and the lower mold or between the upper beam and the upper mold so that the deflection amounts of the upper beam and the lower beam become appropriate values. The actuator drive control is performed, and thereafter the pressurization control is restarted.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the embodiments shown in the accompanying drawings.

FIG. 2 shows an embodiment of the present invention.
This press brake has a die 1, a punch 2, an upper beam 4, a lower beam 5, a pressure cylinder 6 for pressurizing the upper beam 4, a frame base 7, and a table 10.

A strain detector 8 for detecting the strain of the upper beam 4 is provided between the punch 2 and the upper beam 4. The strain detector 8 has a plurality of strain sensors SU1 along the longitudinal direction of the punch 2. ~ SUn is provided.

A strain detector 9 for detecting the strain of the lower beam 5 is provided between the die 1 and the lower beam 5, and the strain detector 9 has a plurality of strain sensors along the longitudinal direction of the die 1. SD1 to SDn are provided.

Further, in this case, a plurality of deflection correction actuators ACT1 to ACTn are arranged between the lower beam 5 and the strain detecting section 10 along the longitudinal direction of the lower beam 5 in order to correct the deflection of the lower beam 5.

FIG. 3 shows an example of a hydraulic circuit when hydraulic cylinders are used as the plurality of deflection correction actuators ACT1 to ACTn. In this case, the piston movements of the plurality of hydraulic cylinders ACT1 to ACTn in the vertical direction. Deflection of the lower beam 5 is corrected by pressing the lower beam 5 by. It should be noted that the hydraulic cylinders ACT1 to ACTn of the present embodiment are respectively provided with pressure sensors, and these pressure sensors detect the pressing force at each position, respectively.

Pressure control valves VL1 to VLn are connected to the hydraulic cylinders ACT1 to ACTn via pilot check valves (check valves) PCHB1 to PCHBn, respectively.

The solenoid valve SOL1 turns on / off the check valve function of the pilot check valves PCHB1 to PCHBn. When the solenoid valve SOL1 is turned on, the pilot check valves PCHB1 to PCHBn are released (the check valve function is abandoned). Then, the oil in each hydraulic cylinder ACT1 to ACTn is drained. When the solenoid valve SOL1 is off, the pilot check valves PCHB1 to PCHBn are closed and the oil in the hydraulic cylinders ACT1 to ACTn is not drained.

The solenoid valve SOL2 performs switching control for supplying oil from the pump P to the pilot check valves PCHB1 to PCHBn. The solenoid valve SOL2
When is turned on, oil from the hydraulic pump P is supplied to the pilot check valves PCHB1 to PCHBn. Although the solenoid valve SOL2 is in the state shown in the figure when the solenoid valve SOL2 is off, the pilot check valve PCHB
1 ~ PCHBn is interposed, so solenoid valve SOL2
Check valve PCHB1 to PCH
If Bn is not released, the oil in each hydraulic cylinder ACT1 to ACTn will not be drained. In addition, M is a hydraulic motor,
Reference numeral 11 is a relief valve.

FIG. 4 shows an example of the configuration of the control system. The upper mold strain sensors SU1 to SUm and the lower mold strain sensor SD are shown in FIG.
Each output of 1 to SDm is analog-to-digital converted by the A / D converters 22 and 23 and input to the NC device 30.

On the other hand, the NC device 30 is the above hydraulic cylinder.
D / A converter 2 sends various command signals to drive ACT1 to ACTn
It outputs to pressure control valves VL1 to VLn and solenoid valves SOL1 and SOL2 via 0, 24 and 26 and amplifiers 21, 25 and 27.

The specific operation of this embodiment will be described below with reference to the flow chart of FIG. In the initial state before driving the press brake, pressure control valves VL1 to V
Ln is in an unload state, and solenoid valves SOL1 and SOL2 are in an off state. That is, in this initial state, no hydraulic pressure is supplied to each hydraulic cylinder ACT1 to ACTn. It is assumed that the pistons of the hydraulic cylinders ACT1 to ACTn are stopped in the middle of the stroke by means such as springs provided inside the hydraulic cylinders ACT1 to ACTn.

In this state, the NC device 30 starts descending the upper beam (step 100). Due to the lowering of the ram, the punch 2 then comes into contact with the work 3 to start pressing the work 3 (step 110). During the bending process after the start of pressurization, the NC device 30 stops the lowering of the upper beam midway (step 120).

The NC device 30 takes in the detection output of each pressure sensor attached to each hydraulic cylinder ACT1 to ACTn with the upper beam stopped (step 130).
Turn on the solenoid valve SOL2 and turn on each hydraulic cylinder AC.
Pressure oil is supplied to T1-ACTn, and each hydraulic cylinder ACT1-
A command signal is output to the pressure control valves VL1 to VLn so that the cylinder initial hydraulic pressure of ACTn becomes the same as the output of each pressure sensor (step 140).

Next, the NC device 30 uses all the strain sensors SU.
The detection outputs of 1 to SUn and SD1 to SDn are sequentially fetched (steps 150 to 180), and the deflection amounts of the upper beam 4 and the lower beam 5 are calculated from these detection outputs (step 190),
Further, the deflection amounts of the upper beam 4 and the lower beam 5 are compared to determine whether the deflection amounts of the upper beam 4 and the lower beam 5 are proper (step 200).

When the amount of deflection is inappropriate, the NC device 30 sequentially corrects the command signals for the pressure control valves VL1 to VLn to sequentially correct the cylinder pressures of the hydraulic cylinders ACT1 to ACTn (step 210-210). 240).
Then, again, the detection outputs of the strain sensors SU1 to SUn and SD1 to SDn are sequentially taken in (steps 150 to 180), and the deflection amounts of the upper beam 4 and the lower beam 5 are calculated from these detection outputs (step 190). The deflection amounts of the upper beam 4 and the lower beam 5 are compared with each other, and it is determined again whether the deflection amounts of the upper beam 4 and the lower beam 5 are proper (step 200). Such cylinder pressure correction is repeatedly executed until the deflection amounts of the upper beam 4 and the lower beam 5 become appropriate.

When the amount of deflection becomes appropriate, N
The C device 30 holds the cylinder displacement amounts of all the hydraulic cylinders ACT1 to ACTn by turning off the solenoid valve SOL2 (step 250).

After that, the NC device 30 corrects the lower limit position of lowering of the upper beam 4 in accordance with the deflection amounts of the upper beam 4 and the lower beam 5 (step 260).

Then, the NC device 30 finishes the pressurizing process by lowering the upper beam 4 to the corrected lower limit position, and then raises the upper beam to the original standby position (steps 270 to 290). Further, by turning on the solenoid valve SOL1, the pressure oil of all the hydraulic cylinders ACT1 to ACTn is drained (step 300).

As described above, according to this embodiment, the deflection of the upper beam and the lower beam is detected during the pressing process, and the deflection amount of the lower beam is corrected to the optimum value based on the detected value. Therefore, a uniform bending angle can be obtained over the entire bending length without performing a trial process.

Although the deflection correcting hydraulic cylinders ACT2 to ACTn are arranged on the lower beam 5 side in the above embodiment, the deflection correcting hydraulic cylinders ACT2 to ACTn may be provided on the upper beam 4 side. .. Also, these hydraulic cylinders ACT2
˜ACTn may be provided in both the upper beam 4 and the lower beam 5. Further, the plurality of wedges described above may be used as the actuator for correcting the deflection. When a wedge is used, the pressure should be temporarily released when the wedge is driven.

In the above embodiment, the present invention is applied to the press brake that applies pressure only by the upper beam 4, but the present invention is also applied to the press brake that moves the die 1 side. Good.

[0033]

As described above, according to the present invention,
The lowering of the upper beam is stopped on the way from the start of pressurization to the completion of pressurization, and the distortion amount of the lower beam and the upper beam is detected in this stopped state, and the deflection amount of the upper beam and the lower beam is detected according to the detected value Since the drive control is performed between the lower beam and the lower mold or between the upper beam and the upper mold so that the actuators are distributed along the direction of the bending line, A uniform bending angle can be obtained over the entire bending length without performing a process.

[Brief description of drawings]

FIG. 1 is a flow chart showing an embodiment of the present invention.

FIG. 2 is a conceptual diagram of a press brake showing an embodiment of the present invention.

FIG. 3 is a hydraulic circuit diagram showing an embodiment of the present invention.

FIG. 4 is a block diagram of a control system showing an embodiment of the present invention.

FIG. 5 is a diagram conceptually showing bending by a press brake.

FIG. 6 is a diagram showing a bending state of an upper beam and a lower beam of a press brake.

FIG. 7 is a diagram showing a middle opening of a work.

[Explanation of symbols]

 1 ... Die 2 ... Punch 3 ... Work 4 ... Upper beam 5 ... Lower beam 6 ... Pressurizing cylinder 7 ... Frame base 8 ... Strain detection unit 9 ... Strain detection unit 10 ... Table 30 ... NC device SU1-SUn ... Strain sensor SD1 to SDn ... Strain sensor ACT1 to ACTn ... Actuator (hydraulic cylinder) VL1 to VLn ... Pressure control valve SOL1, SOL2 ... Solenoid valve

Claims (1)

[Claims] 1. A press brake for bending a work between the punch and the die by moving a punch attached to the upper beam and a die attached to the lower beam, the press brake being provided along the longitudinal direction of the upper beam. A plurality of upper beam strain sensors for detecting the deflection of the upper beam; a plurality of lower beam strain sensors provided along the longitudinal direction of the lower beam for detecting the deflection of the lower beam; Dispersed along the direction of the bending line between the beam and the lower mold or between the upper beam and the upper mold,
A plurality of actuators for applying vertical pressure to the lower mold or the upper mold, and stopping the lowering of the upper beam in the middle of the start of pressurization to the completion of pressurization. The detection outputs of the strain sensor for the lower beam and the strain sensor for the lower beam are fetched, and the deflection amounts of the upper beam and the lower beam are calculated based on the respective detection outputs, and the deflection amounts of the upper beam and the lower beam are appropriate based on the calculated values. A middle-opening correction device for a press brake, comprising: a control unit that controls driving of the plurality of actuators so that the values become a value, and then performs control to restart pressurization control.