JPH03184628A - Abnormality detecting method for servo valve in press brake - Google Patents

Abstract

PURPOSE:To rapidly detect the abnormality and to previously prevent a serious accident from generating by discriminating the abnormality of the servo valve of the press brake by utilizing the gain changing signal. CONSTITUTION:Because after outputting the instruction signal to position the ram 3, the abnormality of the servo valve is detected by comparing the generating state of the gain switching signal and the positioning completion signal fed back from each hydraulic pressurizing position nodule with that of the normal state, the abnormal state of the one side shaft stopping, etc., is rapidly detected, in this time the alarming is outputted, and the generation of large accident is previously prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a method for detecting abnormality in a servo valve of a press brake, which allows the press brake to be operated safely.

(Prior Art) As an example of a conventional press brake, a pair of cylinder devices driven by servo valves are arranged near both ends of a ram that supports a movable mold, and the movable mold is moved close to the fixed mold.
A press brake main body that bends the workpiece interposed between both molds by separating the two molds, an NC device that calculates a positioning target value for the ram based on bending data, and an NC device that is provided for each servo valve. There is an example of a device including a hydraulic position module that receives positioning command signals output from the device and controls the servo valve while appropriately switching the gain.

In this type of press brake, the Nc device calculates the target value at which the ram should be moved, outputs a positioning υ command to both hydraulic position modules, and completes the bending by outputting a positioning completion signal from the module. can be considered.

Conventionally, in this type of press brake, if it takes too much time (for example, 30 seconds) for the positioning completion signal to be output from the Gakko Joule, it is assumed that there is some kind of force abnormality in the servo valve or the machine. It was assumed that this had occurred and an alarm was generated.

(Problem to be Solved by the Invention) However, in the conventional press brake as described above, the time between the output of a positioning command and the output of a positioning completion signal to detect an abnormality in the servo valve is too long. Since the return was such that an alarm was issued only when the time was long, there was a problem in that small abnormalities could not be detected and there was a lack of safety.

Therefore, the present invention provides a press brake as described above.
The purpose of the present invention is to provide a method for detecting abnormalities in servo valves of press brakes that can prevent accidents.

[Return of the Invention] (Means for Solving the Problems) The present invention for solving the above-mentioned problems comprises disposing a pair of cylinder devices driven by servo valves near both ends of a ram that supports the movable mold, and a press brake body that bends a workpiece interposed between both molds by moving the press brake toward and away from a fixed mold; an NC device that calculates a positioning target value of the ram based on bending data; A servo valve abnormality detection signal method for a press brake, comprising a hydraulic position module provided for each servo valve, which inputs positioning command signals output from the NC device and controls the servo valve while appropriately switching the gain. ,
The abnormal state of the servo valve is detected by comparing the generation status of the positioning completion signal and the gain switching signal returned from each hydraulic position module after the output of the positioning command signal with the normal state.

(Operation) In the press brake servo valve abnormality detection method of the present invention,
In the above feedback, the abnormal state of the servo valve is detected by comparing the generation status of the positioning completion signal and gain switching signal returned from each hydraulic position module after the output of the positioning command signal with the normal state. Based on the relationship between the positioning completion signal and the gain switching signal, it is possible to quickly detect abnormal conditions such as one-axis stop, and by outputting an alarm at this point, it is possible to prevent major accidents. can.

(Example) The present invention will be explained in detail below.

FIG. 2 is a front view of a press brake implementing the present invention.

In the figure, a main body 1 of the press brake has a fixed lower apron 2 and a ram (upper apron) 3 that is driven up and down with respect to the apron 2.

A die 4 as a lower mold is placed on the upper part of the lower apron 2, and a punch 5 as an upper mold is attached to the lower part of the ram 3.

In order to detect the upward and downward movement of the ram 3 in the vertical direction (D-axis direction), encoders E for detecting the positions of both ends of the ram 3 are respectively provided in a frame portion (not shown).

Further, in order to drive the ram 3 up and down, cylinder devices f6 are provided at both ends of the frame portion (not shown). Both cylinder devices 6 are connected to a servo valve 8 that appropriately adjusts and supplies the pressure oil supplied from the hydraulic pump 7 to the cylinder device 6.

Furthermore, 2 gM pressure sensors P1 and P2 are provided in the upper cylinder chamber of the cylinder device 6 to detect the pressurizing force. One pressure sensor PI is for a (pressure), and the other pressure sensor P2 is for high pressure, and both pressure sensors p and P2 are used by switching as appropriate depending on the pressure value to be detected.

Note that each apron 2.3 is provided with a strain meter 9 for detecting the strain state of each apron.

FIG. 3 shows the NC device 1 that controls the servo valves (8A, 8B) for the pair of D axes (DI axis, D2 axis) as described above.
0 and hydraulic position module 11 (IIA, II
B) is a block diagram.

The NC device 10 includes a target value calculation means 12 for controlling the positioning of the ram 3 according to input bending data, and an abnormality determination circuit 15 including first and second timers 13, 14, 13-14-. It is equipped with

The hydraulic position modules IIA and IIB are fed back in a closed loop to obtain a feedback signal from the encoder E to the servo valves 8A and 8B, and are fed back to the servo valves 8A and 8B in order to move the ram 3 to the manually input target value. Control signal(
voltage).

The NC device 10 and each hydraulic position module IIA
, IIB are connected by a serial communication line, and the NC device 10 outputs a positioning command signal 0P16 for both modules IIA and IIB.

Each hydraulic position module IIA, IIB operates individually and tries to operate said ram 3 individually to the desired value. At this time, in order to perform highly accurate machining, a speed switching position and a gain switching position are set in each hydraulic position module IIA, 11B, and the speed switching and gain switching are performed at the set positions.

Therefore, in this example, when this gain switching is performed, a gain switching signal 0P42 is generated and this is sent to the NC device 1.
I am trying to send it to 0. Also, as in the conventional case, a positioning completion signal 0P44 is sent out.

As shown in FIG. 4, in step 401, the NC device 1
0 outputs the positioning command signal 0P16 to both hydraulic position modules IIA and IIB, step 4
02.403 with both position modules IIA and IIB
are executed simultaneously by multitasking. Also, when executing it,
The abnormality determination circuit 15 of the NC device 10 executes the processing shown in FIG. 1(a) and FIG. 1(b) for each module 11A111B.

First, the control diagram shown in FIG. 5 will be explained. The solid line shows the command value, and the broken line shows the actual value. Time t for horizontal pongee, D for vertical pongee
Take the axis.

In the figure, D2 shows the gain switching position, D3 shows the speed switching position, and D4 shows the final target position. It is assumed that the positioning completion signal for the target value D3 is output at the position D1, for example, 4 mm before the target value D3. In addition, D2
, D3 is about 1 mm.

In the above control l#s diagram, as shown by the solid line, the ram 3 is initially at high speed, decelerated from the gain switching position, temporarily stopped at the target position D3, and then finally stopped at the final target position D4.
move at low speed. At this time, under normal conditions, the position,
A positioning completion signal 0P44 is output on the condition that 60m5 has passed since entering the vehicle. Also, a gain switching signal 0P42 is output at position D2. In addition, under normal conditions,
Since the time from position D2 to D3 is very short, the positioning completion signal 0P44 is output after reaching the target position D3.

Now, the abnormality determination circuit 15 of the NC device ffl0 is
Discrimination processes I and (2) in FIGS. 1(a) and 1(b) are executed. FIG. 1(1) shows the processing for the module 11A, and FIG. 1(b) shows the processing for the module 11B. Since the process shown in FIG. 1(b) is correlated with the process in FIG. 1(a), corresponding steps are indicated by the same number with a dash ('). The time set in the first timer 13.13- is 0.15 to 0.
37 seconds, and the time set in the second timer 14, 14' is about 1 second.

In FIG. 1(a), when the gain switching signal 0P42■ is input in step 101, the first
The timer 13 is set to a time of 0.15 to 0.37 seconds.

In step 103, the positioning completion signal 0P44■ determines the human power, and the step 104 continues until the positioning completion signal 0P44■ is input.
In step 105, it is determined whether the timer 13 has timed out, and if the positioning completion signal 0P44■ is not manually input before the time elapses, an alarm is generated in step 105. Thereby, it is possible to determine an abnormal state in which the positioning completion signal 0P44■ is not inputted easily.

Next, until the time-up of timer 1 is confirmed in step 104, the positioning completion signal is 0 in step 103.
If P44<& is input, the module 11A is normal to this extent. Therefore, in steps 106 and subsequent steps, the relationship with other modules 11B is inspected.

In step 106, it is determined whether the gain switching signal 0P420 for the other module 0 is manually input or not, and if it is not, an alarm is outputted by the steering knob 110 as the modules are not balanced.

Further, if the gain switching signal 0P420 for the other module IIB is manually input in step 106, the second timer 14 is started in step 107, and during this time the positioning completion signal 0P440 of the other module IIB is output in step 108 and 109. Determine whether or not it was done manually. If there is no manual intervention during this time, step 11
Outputs an alarm when the value is 0. Therefore, step 107
Through the processing in steps 109 to 109, it is possible to determine the delay in the positioning completion signal of the other module 11B.

Regarding FIG. 1(b), the processing for module 11B is similarly executed.

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 positioning completion signal between modules, various types of errors such as single-axis stop can be detected for conditions different from normal ones. It can determine abnormal conditions and output alarms.

As described above, in this example, FIGS. 1(a) to 1(b)
), it is possible to identify various abnormal operations, and it is possible to output an alarm before a major accident occurs that could result in a defective product or damage the machine.

The present invention is not limited to the discrimination methods shown in FIGS. 1(a) and 1(b), but can discriminate various abnormal states by discriminating the gain switching signal 0P42 under various conditions. I can do it. For example, since the NC device also manages the position of the encoder, the gain switching signal 0P42
Depending on the current state at the time of input or the state of no input, when the preset normal state is not entered, all other states can be determined as abnormal and an alarm output can be made.

The present invention is not limited to the above embodiments, but can be implemented in any appropriate manner by making appropriate design changes.

[Effects of the Invention] The present invention is a press brake servo valve abnormality detection method that uses a gain switching signal to determine an abnormal state.
Abnormal conditions such as one shaft stopping can be quickly detected.
It is possible to prevent a major accident from occurring.

[Brief explanation of drawings]

The drawings all show embodiments of the present invention, and FIGS. 1(a) and 1(b) are flowcharts showing an abnormality determination routine for each axis, FIG. 2 is a front view showing an example of a press brake, and FIG. 3 is an explanatory diagram of the NC device and the hydraulic position module, FIG. 4 is a flowchart showing a processing method of a positioning command signal, and FIG. 5 is a control diagram of the hydraulic position module. 10...NC device 11 (IIA, IIB)...Hydraulic position module 0P16...Positioning command signal 0P42...Gain switching signal 0P44...Positioning completion signal

Claims (1)

[Claims] A pair of cylinder devices driven by servo valves are arranged near both ends of the ram supporting the movable mold, and the movable mold approaches and moves away from the fixed mold, thereby removing the workpiece interposed between the two molds. The press brake body to be bent,
An NC device that calculates a positioning target value for the ram based on the bending data, and a positioning command signal provided for each servo valve and outputted by the NC device are respectively inputted to control the servo valve while appropriately switching the gain. In the servo valve abnormality detection method for a press brake equipped with a hydraulic position module, the generation status of the positioning completion signal and gain switching signal returned from each hydraulic position module after the output of the positioning command signal is compared with the normal state. A method for detecting abnormality in a servo valve of a press brake, characterized in that an abnormal state of the servo valve is detected by: