JP2818456B2 - Press brake - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a press brake that can be operated safely.

(Prior Art) In a conventional press brake, there is an example in which a mold inclination is mechanically detected by a limit switch or the like, and an alarm is output for an extreme inclination.

(Problems to be Solved by the Invention) However, in the press brake as described above, a relatively large inclination can be detected so as not to damage the machine, but a small inclination cannot be detected. There is a problem that the load cannot be detected.

The so-called one-sided load is caused by a load imbalance near the both ends of the mold generated near the final bending position, and it is important to effectively detect this and to protect the mold and improve the product accuracy.

Accordingly, an object of the present invention is to provide a press brake capable of detecting not only a large inclination of a table but also a single load.

(Means for Solving the Problems) In view of the above-mentioned conventional problems, the invention according to claim 1 vertically moves an upper table having an upper mold and a lower table having a lower mold. In a press brake, which is provided to face each other, and one of the tables serves as a movable table capable of moving up and down, a left and right elevating device for vertically moving left and right sides of the moving table, A left and right elevating position detecting device for detecting a vertical movement position, and a control device capable of individually controlling the left and right elevating operation devices, wherein the control device detects a value detected by the left and right elevating position detecting device. A single load detector is provided for detecting a single load based on the difference between the two, and the moving table is first moved at a high speed toward the final target position, decelerated from the gain switching position, and then slowly moved to the final target position. This is a configuration for controlling the moving table to move.

According to a second aspect of the present invention, there is provided a press brake in which a bending work is performed by interposing a workpiece between opposed dies and causing the two dies to relatively approach / separate from each other. Position detecting means for detecting the moving positions of both ends of the moving table for driving the mold are provided. A pair of cylinder devices driven by servo valves are provided near both ends of the moving table, and the moving table is provided based on bending data. An NC device for calculating the positioning target value is provided, and a hydraulic position module is provided for each servo valve and controls the servo valve while inputting a positioning command signal output by the NC device and appropriately switching the gain. And the state of generation of the positioning completion signal and the gain switching signal that are fed back from each hydraulic position module after the output of the positioning command signal. First comparing means for detecting an abnormal state of the servo valve and outputting an alarm by comparing the condition with that at the time of normal operation, wherein both end positions of the moving table detected by the position detecting means are located near the final target position. And a second comparing means for outputting an alarm when the difference between both end positions of the moving table is larger than a reference amount.

(Example) Hereinafter, an example of the present invention will be described.

FIG. 1 is a front view of a press brake embodying the present invention.

In the figure, a press brake 1 has a lower fixed table 2 and a movable table 3 driven to move up and down with respect to the table 2.

A die 4 as a lower mold is placed on an upper part of the fixed table 2, and a punch 5 as an upper mold is mounted on a lower part of the movable table 3.

Encoders E for detecting both end positions of the moving table 3 are provided in a frame portion (not shown) as a moving position detecting device for detecting the moving position of the moving table 3 in the vertical direction (D-axis direction) on both left and right sides. Have been.

Further, in order to drive the moving table 3 up and down, cylinder devices 6 are provided at both ends of a frame portion (not shown) as a lifting and lowering device. Servo valves SV1 and SV2 are connected to the two cylinder devices 6 to supply the hydraulic pressure supplied from the hydraulic pump 7 to the cylinder devices 6 at appropriate flow rates.

Wherein the cylinder upper chamber of the cylinder device 6, the two pressure sensors P ₁ and P ₂ for detecting pressure is provided. One pressure sensor P ₁ is for low pressure and the other pressure sensor P ₂
Is for high pressure, and both pressure sensors P ₁ and P ₂ are appropriately switched and used according to the pressure value to be detected.

Further, each of the tables 2 and 3 is provided with a strain gauge 8 for detecting a distortion state of each table.

FIG. 2 is an explanatory diagram of a hydraulic circuit including the servo valves SV1 and SV2.

In the figure, the hydraulic circuit of the present example has a pair of cylinder devices 6 (CYL1, CYL2) arranged at both ends of a moving table 3 extending left and right as viewed from the front side of the press brake body. By moving the pistons PST1 and PST2 simultaneously hydraulically, the moving table 3 is driven to move up and down. Rack LS at both ends of moving table 3
C1 and 2 are fixed, and the encoder E detects the amount of rotation of the pinion meshed with the rack, so that the elevation position of the moving table 3 can be detected.

The hydraulic circuit absorbs oil in the oil tank OT shown in the lower part of the figure through the suction filter SFN, and
An oil pump 7 that discharges to the pipe OL1 via the LF is provided. The line filter ILF has a pressure switch PS1 for detecting the pressure difference between the input and output sides and detecting the clogging.
Is provided. The piping OL1 is provided with a proportional solenoid valve SOLE for pressure adjustment and a pressure switch PS2 for detecting a pressure rise. An oil purifier 9 is arranged on the side of the oil tank OT.

The pipe OL1 is provided with two servo valves SV1 and SV2 for driving the cylinder devices CYL1 and CYL2, each of which is switchable in direction and adjustable in flow rate.

First, the circuit including the servo valve SV1 shown on the left side of the figure shows that the servo valve SV1 receives one of
The port is driven so as to be connectable to the two ports on the other side in parallel or crosswise, and the two ports on one side are connected to the pipe OL1 and the drain pipe OL2.

One of the other two ports of the servo valve SV1 is connected to the upper chamber of the cylinder device CYL1 via a pipe OL3. The other port is connected to a pipe OL4, which is connected to a pipe OL5 via a pilot-type logic valve LV1, and this pipe OL5 is a counterbalance valve.
It is connected to pipe OL6 via CBV1. Piping OL5 and OL6
A bypass pipe OL7 provided with a logic valve LV2 with a pilot is provided between them. The pipe OL6 is connected to the lower chamber side of the cylinder device CYL1. The logic valve LV
Pilot part 1 is connected to piping OL7 via solenoid valve SOL3.
Or it is connected to the drain pipe. Further, a pilot portion of the logic valve LV2 is connected to the pipe OL6 or the drain pipe via a solenoid valve SOL4. A pressure switch PS3 is provided in the pipe OL6.

A pipe OL8 is connected to an upper chamber of the cylinder device CYL1, and a drain pipe is connected to the pipe OL8 via a logic valve LV3 with a pilot. This logic valve LV3
The pilot section can input a pilot pressure of the pipe OL1 via a solenoid valve SOL5.

The same applies to the other cylinder device CYL2. Corresponding members are denoted by the same reference numerals. A pressure sensor SD is provided between the two pipes OL3.

In the hydraulic circuit having the above configuration, for example, when the circuit on the left side is shown, the servo valve SV1 is in the illustrated state, and the piping OL1
, And pressurized oil flows into the upper chamber of the cylinder device CYL1. Then, by the solenoid valve SOL3 which is turned on based on the on operation of the descending foot petal (not shown),
The logic valve LV1 is opened, and the oil in the lower chamber flows to the pipe OL4 via the pipe OL6, the counter balance valve CBV1, and the logic valve LV1.

On the other hand, when the servo valve SV1 is operated in the reverse direction, the pressure oil in the pipe OL1 flows into the lower chamber of the cylinder device CYL1 through the pipes OL4 and OL5, the logic valve LV2, and the pipe OL6, and raises the ram 1. The same applies to the cylinder device CYL2. During this time, the pressure sensor SD detects the pressure of the pipe OL3.

FIG. 3 shows a pair of left and right D axes (D1 axis, D2 axis) as described above.
Is a control device that can individually control the servo valves (SV1, SV2) for the NC device 10 that constitutes the control device.
FIG. 4 is a block diagram of a hydraulic position module 11 (11A, 11B).

The NC device 10 includes a target value calculating means 12 for calculating a target value for controlling the positioning of the moving table 3 according to the input bending data, and first and second timers 13, 14, 1
An abnormality determination circuit 15 including 3 'and 14' (also called timers 1, 2, 3, and 4) is provided. Further, a one-side load detecting unit 16 is provided.

The hydraulic position modules 11A and 11B are servo valves SV
1. A closed loop for obtaining a feedback signal of the encoder E for SV2, and outputs a control signal (voltage) to the servo valves SV1 and SV2 in order to drive the moving table 3 to the input target value.

The NC device 10 and each hydraulic position module 11A, 11B
Is connected by a serial communication line, and the NC unit
10 outputs a positioning command signal OP16 to both modules 11A and 11B. The positioning command signal OP16 is a command including a target position and a command speed for the target position.

Each of the hydraulic position modules 11A and 11B operates individually, and attempts to individually move the moving table 3 to the target position. At this time, in order to perform high-precision machining, each hydraulic position module 11A, 11B has a speed switching position,
A gain switching position is set, and speed switching and gain switching are performed at the set position.

Therefore, in this example, when this gain switching is performed,
A gain switching signal OP42 is generated and transmitted to the NC device 10. The positioning completion signal OP44 is transmitted at the timing shown in FIG.

As shown in FIG. 4, in step 401, the NC device 10 sends the positioning command signal OP16 to both hydraulic position modules 11
When output is performed to A and 11B, in steps 402 and 403, both position modules 11A and 11B execute the positioning work simultaneously in multitask. At the time of the execution, the abnormality determination circuit 15 of the NC device 10 executes the processing shown in FIGS. 6A and 6B on each of the modules 11A and 11B. further,
Thereafter, the one-sided load detection unit 16 detects the one-sided load.

First, the control diagram of FIG. 5 will be described. A solid line indicates a command value, and a broken line indicates an actual value. The horizontal axis indicates time t, and the vertical axis indicates D axis. Indicates an example of an abnormal state.

In FIG, D ₂ is the gain changeover position, D ₃ is speed switching position (target position), D ₄ represents the final target position. Positioning completion signal to the target value D ₃ than the target value D _3, and shall be outputted for example, in the position D ₁ of the 4mm front. However, the positioning completion signal is output after a predetermined time from the arrival at the position D ₁ (e.g., 60 ms). The distance between the D _2, D ₃ is 1mm
It is about.

In the control diagram discussed above, the moving table 3, as shown by the solid line, initially fast, is decelerated from the gain switching position and temporarily stopped at the target position D _3, then the final target position
D to ₄ moves at low speed. At this time, in the normal state, the position D ₁
The positioning completion signal OP44 is output on condition that 60 ms has passed since the entry. The gain switching signal at the position D ₂
OP42 is output. Normally, D ₃ from position D ₁ through D ₂
Is very short, so the positioning complete signal
OP44 is output after reaching the target position D _3.

Now, the abnormality determination circuit 15 of the NC device 10 executes the determination processes I and II in FIGS. 6 (a) and 6 (b). FIG. 6A shows the processing for the module 11A, and FIG.
FIG. 7B shows the processing for the module 11B. Since the processing shown in FIG. 6 (b) has a relative relationship to the processing of FIG. 6 (a), corresponding steps are denoted by the same numbers with the dash (') sign attached. First timer 1
The time set in 3, 13 'is 0.15 to 0.37 seconds, and the time set in the second timers 14, 14' is about 1 second.

In FIG. 6A, when the gain switching signal OP42 is input in step 101, a time of 0.15 to 0.37 seconds is set in the first timer 13 in step 102.

In step 603, the input of the positioning completion signal OP44 is determined.Until the input of OP44, the timer 13 is determined to be timed up in step 604.If the positioning completion signal OP44 is not input until the time elapses, At step 605, an alarm is issued. Thus, it is possible to determine an abnormal state where the positioning completion signal OP44 is not easily input.

Next, in step 603, until the time-up of the timer 1 is confirmed in step 604, the positioning completion signal OP44
Is input, the module 11A is normal to this extent. Therefore, in step 606 and subsequent steps, an inspection is performed in relation to the other module 11B.

In step 606, it is determined whether or not the gain switching signal OP42 for another module has been input,
If not, an alarm is output in step 610 assuming that the balance between the modules has not been achieved.

If the gain switching signal OP42 for the other module 11B has been input in step 606,
In step 7, the second timer 14 is started.
During this time, the positioning completion signal OP44 of the other module 11B
It is determined whether or not is input. If not input during this time, an alarm is output in step 610. Therefore, the delay of the positioning completion signal of another module 11B can be determined by the processing of steps 607 to 609.

The processing for the module 11B is similarly executed for FIG. 6 (b).

Therefore, in this example, by inspecting the delay of the positioning completion signal with respect to the gain switching signal, and the delay of the gain switching signal and the positioning completion signal between modules, various types of operations such as one-axis stop in a state different from the normal state are performed. An abnormal state can be determined and an alarm can be output.

As described above, the moving table 3 has the target position D _{4 in the} regular form.
It descends to the vicinity. Therefore, in this example, the fourth
Processing III shown in step 404 in the figure is executed.

 The details of this treatment III are shown in FIG.

In step 701, detection positions for both axes D1 and D2
Enter D ₁ and D ₂ .

 In step 702, a comparison is made using the following equation.

| D ₁ − (D ₂ + DS) | ≧ α α is a parameter, which can be arbitrarily determined by the user. Specifically, to detect one-sided load, 0.
This is a value set to about 05mm. DS is an offset value. The offset value DS is set when the work is performed while the moving table 3 is intentionally tilted.

Therefore, if the difference between the detected values of the two axes D ₁ and D ₂ is equal to or larger than the set value α in step 702, this is regarded as a single load, and an alarm is output in step 703.

As described above, in this example, the one-side load is accurately detected, and the product failure and the mold breakage due to the one-side load can be prevented.

Moreover, since various abnormal states of both axes D1 and D2 such as one-axis stop are detected in the processing I and II shown in FIG. 4, safe and reliable bending work can be executed in all work.

The present invention is not limited to the above-described determination method, and various abnormal states can be determined by determining the gain switching signal OP42 under various conditions. For example, since the NC device also performs the position management of the encoder, when the gain switching signal OP42 is input, or according to the current state of the state where it is not input, when it does not enter a preset normal state, It is possible to determine that all other states are abnormal and output an alarm.

The present invention is not limited to the above embodiment, but can be implemented in an appropriate mode by making appropriate design changes.

[Effects of the Invention] As can be understood from the above description of the embodiments,
According to the present invention, the left and right sides of the moving table can be individually controlled by the control device, and the one-sided load can be detected based on the difference between the vertical movement positions of the left and right sides, and the inclination of the moving table can be corrected. At the same time, the moving table is initially moved at a high speed, and the moving table can be controlled at a low speed to the final target position by decelerating from the gain switching position, so that the moving table tends to tilt due to a single load, for example. Also, the right and left sides of the moving table can be quickly and accurately positioned at the respective final target positions, and efficient and accurate bending can be performed.

Further, when an abnormal state is determined using the gain switching signal, an abnormal state such as a one-axis stop can be quickly detected, and a major accident can be prevented from occurring.

[Brief description of the drawings]

FIG. 1 shows an embodiment of the present invention. FIG. 1 is a front view of a press brake, FIG. 2 is an explanatory view of a hydraulic circuit, FIG. 3 is an explanatory view of an NC device and a hydraulic position module, and FIG. FIG. 5 is a control diagram of the hydraulic position module, FIGS. 6 (a) and 6 (b) are flowcharts showing an abnormality determination routine for each axis, and FIG. 5 is a flowchart showing a one-sided load detection method. 3: Moving table 10: NC unit 11 (11A, 11B) ... Hydraulic position module OP16 ... Positioning command signal OP42 ... Gain switching signal OP44 ... Positioning completion signal SV1, SV2 ... Servo valve LSC1, 2 ... ... Rack E ... Encoder

Claims (2)

(57) [Claims] 1. A press brake comprising an upper table provided with an upper mold and a lower table provided with a lower mold which are vertically opposed to each other, and one of the tables is a movable table capable of moving up and down. The left and right elevating actuators for vertically moving the left and right both sides of the table, the left and right elevating position detecting devices for detecting the up and down movement positions of the left and right both sides of the moving table, and the left and right elevating actuators are separately provided. And a control device that can control the load, the control device includes a single load detection unit that detects a single load based on the difference between the detection values of the left and right lifting position detection devices, and firstly toward the final target position. A press brake for moving the moving table at high speed, decelerating from the gain switching position, and then moving the moving table to the final target position at low speed. 2. A press brake for performing a bending process by interposing a workpiece between opposed dies and causing the two dies to relatively approach / separate from each other, and drives a movable die among the dies. Position detecting means for detecting the moving positions of both ends of the moving table are provided, and a pair of cylinder devices driven by servo valves are provided near both ends of the moving table, and a positioning target value of the moving table is determined based on bending data. An NC device for calculating is provided, and a hydraulic position module for controlling the servo valve while inputting a positioning command signal output from the NC device provided for each servo valve and appropriately switching a gain is provided, and the positioning command signal is provided. The status of the positioning completion signal and gain switching signal returned from each hydraulic position module after the output of First comparing means for detecting an abnormal state of the servo valve and outputting an alarm by comparing the two positions of the moving table detected by the position detecting means in the vicinity of the final target position; A pulley brake comprising a second comparing means for outputting an alarm when a difference between both end positions of the table is larger than a reference amount.