JPS63311507A - Control method for robot - Google Patents

Abstract

PURPOSE:To improve the operability of maintenance when an abnormality occurs by automatically permitting a processing head to recede in a position on the space shifting path of the processing cycle before the abnormality occurs and apart from processed articles by a prescribed distance so as to permit it to stand by and automatically resetting it if it is restarted. CONSTITUTION:When a welding start miss occurs, the welding torch (processing head) 5 is shifted in the position on the space shifting path of the welding cycle before the welding cycle and apart from the materials 8, 9 to be welded (material to be processed) by the prescribed distance, and is permitted to stand by. Thus, it is unnecessary for a worker to execute a troublesome operation such as to operate a teaching box and to permit a robot 1 to stand by in the prescribed position, whereby the abnormal part in an arc welding equipment (processing equipment) 4 can be mended in extreme smoothness. When mending terminates, the welding torch 5 is returned to the welding start position of the welding cycle when the welding start miss occurs by the starting operation of the worker and the welding cycle is executed again just as it is.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a method for controlling a robot when an abnormality occurs in a processing device in which a processing head is supported by the robot.
In particular, the present invention relates to a robot control method that causes the processing head to retreat to a position a predetermined distance away from the workpiece and wait when an abnormality occurs.

[Conventional technology]

Robots are being introduced in large numbers in automobile production.

Among them, arc welding is widely adopted next to resistance spot welding for welding sheet metal parts of automobiles.
Similar to resistance spot welding, arc welding is mostly performed using automatic machines, and in recent years, automation of welding work using robots has become very common.

In particular, in tracing-type arc welding, as the performance of robots and peripheral equipment such as sensors and computers improve, complex shapes that were completely impossible with conventional mechanical tracing-type specialized machines have become possible. Arc welding of parts has become possible, and it is no longer rare to have dozens of robots on a single welding line.

Naturally, the number of welding lines has also increased significantly, and with this increase in the number of welding lines, the number of times welding start processing and welding end processing has to be performed has also increased significantly compared to the past. It's coming.

On the other hand, although arc welding technology has also greatly improved, arc welding is basically unstable at the start and end of welding. The influence of the material of the workpiece to be welded,
Due to factors such as fluctuations in the feeding speed of the welding wire, the incidence of welding start errors at the start of welding and welding of the welding wire to the workpiece at the end of welding remains high.

As described above, when a large number of robots are used and the number of welding lines is also increased, the frequency of occurrences of welding start errors, welding, etc. increases as a result.

Above all, it is known from experience that welding start errors occur very frequently.

By the way, robots used in conventional arc welding do not have a function to automatically handle the abnormality and restart the welding cycle when the above-mentioned abnormality occurs.

Therefore, if the above-mentioned abnormality occurs, the robot must be stopped together with the arc welding equipment, and the welding line in which the robot is used must also be temporarily stopped using an interlock signal from this robot. It has become.

FIG. 3 shows a processing flow when a welding start error occurs in a conventional arc welding robot.

When welding work is started, first, in step 51 of the processing flow shown in FIG. 3, the robot control device for controlling the robot is initialized, and the cycle number N indicating the number of welding cycles is set to 1. The welding torch, which is the processing head, is set to the next step 52 and moved to the welding start point of the first welding cycle of the welding operation.

After the welding torch is moved to the welding start point of the first cycle, the process flow proceeds to step 53, where a welding start command signal is transmitted from the robot control device to the welding machine control device for controlling the arc welding device. After this transmission,
Proceeding to the next step 54, the system remains in standby for about 0.5 to 1.0 seconds. During this time, the welding machine control device receives the welding start command signal and performs the welding start process, and then After the time has elapsed, the process proceeds to the next step 55, where it is determined whether an arc-on signal indicating that an arc has occurred has been sent from the welding machine control device, and whether or not the arc-on signal is present. For example, the process proceeds to the next step 56, where the welding torch is moved at a predetermined speed to the welding end position of that welding cycle.

Then, the process proceeds to the next step 57 to determine whether or not the welding cycle is the final welding cycle. If it is not the final welding cycle, the process proceeds to step 58 on the left side of the processing flow and increases the number of cycles N by one. let

In this way, steps 51 to 5 of the processing flow
8 is repeated until the final cycle, and when it is confirmed in step 57 that the welding work has been completed up to the final welding cycle, the process proceeds to the next step 59, where the welding torch is returned to the origin and the welding process is repeated until the final cycle. complete all welding cycles.

On the other hand, if a welding start error occurs, the arc-on signal from the welding machine control device will continue even after 0.5 to 1.0 seconds have elapsed after the robot control device started sending the welding start command signal to the welding machine control device. Since the signal is not confirmed, the determination in step 55 of the processing flow shown in FIG. 3 is "NO", and the process proceeds to step 61 on the right side of the processing flow.
Stop sending the welding start command signal to the welding machine control device, stop the welding operation of the arc welding device, and
Proceeding to the next step 62, a welding start error warning signal is transmitted and a warning lamp or warning buzzer is activated. At the same time, the process advances to the next step 63 and the robot is stopped in that state.

In this state, it can be confirmed that the alarm lamp or alarm buzzer is operating, so the operator recognizes this and repairs the abnormality in the arc welding equipment.

Then, in the next step 64, after the repair of the arc welding device is completed, when it is confirmed that the reset button of the welding machine control device is pressed by the operator and an abnormal reset signal is transmitted, the next step is performed. Go to 65, this step 65
When it is confirmed that the start button of the arc welding device is pressed by the operator and a start signal is transmitted, the process returns to the previous step 53 and starts the welding cycle at the time when the abnormality occurred again. Start from.

In this way, when a welding start error occurs, at present, an alarm lamp or alarm buzzer activated by an abnormality signal from the robot control device makes the operator aware of the abnormality in the arc welding equipment and prevents the occurrence of the abnormality. Maintenance of arc welding equipment will be carried out.

By the way, generally, in this arc welding, as shown in FIG. This welding wire 75 and the object to be welded 72 are fed out from the tip of the contact tip 76.
．． Welding is performed by melting the two with the heat of the arc generated between the contact tip 76 and the workpieces 72 and 73, and the distance between the contact tip 76 and the objects 72 and 73 to be welded is as small as 10 or so, and they are quite close to each other.

Therefore, as an example of the welding start error, which occurs particularly frequently, the maintenance work includes replacing the contact tip 76. The contact tip 76 must be replaced if, for example, the welding wire 75 becomes clogged due to wire burnback of the welding wire 75 or excessive sliding resistance inside the contact tip 76. This is done when a case arises where this is not possible.

Such a welding start error naturally occurs when the welding torch 71 is aiming at the welding line 74, so when this problem occurs, the welding torch 7
1 is close to the object to be welded 72° 73, and as it is, the length of the contact tip 76 is longer than the above-mentioned distance, so the contact tip 7
6 replacement work is impossible.

Therefore, in order to replace the contact tip 76, first set the operation mode of the robot to "teaching mode", operate the robot by operating the teaching pendant, and replace the welding torch 71 supported by the robot. is moved to a position where the contact tip 76 can be replaced, that is, to a position away from the objects to be welded 72 and 73, and in this state, the contact tip 76 is replaced. Once this exchange is complete, operate the robot using the teaching pendant to move it close to its original position, then change and set "teaching mode" to "play mode" and start from the middle of each welding cycle. This will require a restart.

[Problem 1 to be solved by the invention] By the way, this repair work is particularly difficult to perform in a fully automatic welding line, where the work to be welded, the robot, etc. are all placed in a safety shelf surrounding the robot, If the area around the welding torch cannot be visually checked from outside the shelf,
"Abnormal occurrence" → "Worker's approach" - ("Open safety shelf" → "Visual check" → [Teaching pendant mode change ("Play" → "Teaching)"] →

"Robot operation using teaching pendant: Moving the welding torch" → "Replacing the contact tip" → "Robot operation: Returning the welding torch" → "Close the safety shelf" → "Mode switching ('Teaching → 1 play')" - This requires the complicated operation of "restart J')" (the details of the worker's work are in parentheses).

Operating the teaching box to operate such a robot is a time-consuming task that requires training, and as a result, the welding line is stopped for a long time. As a result, there is a problem that productivity is reduced.

Note that as processing equipment that takes some kind of action when an abnormality occurs, there are, for example, welding equipment disclosed in JP-A-56-160876 and JP-A-58-154457. The current technology only detects the occurrence of an abnormality and issues an alarm when the abnormality occurs, and has not yet reached the level of solving the above problem.

In addition, as a tracing type arc welding device, JP-A-59-
There are disclosures in Japanese Patent No. 192682 and Japanese Patent No. 59-196173, but they do not describe countermeasures when an abnormality occurs.

Therefore, an object of the present invention is to improve the workability of maintenance when problems such as welding start errors and welding occur, thereby increasing productivity.

[Means for solving problems]

Therefore, when an abnormality such as a welding start error occurs in a processing device, the present invention automatically moves the processing head to a workpiece that is on the spatial movement path of the processing cycle before the abnormality occurs and that is The machining head is moved back and stopped at a position determined as a teaching point that is a predetermined distance away from the machine, and when the abnormality is processed and restarted, the processing head is automatically moved. It is characterized in that the machine is restarted after returning to the machining start position of the machining cycle at the time when the abnormality occurred.

Specifically, by controlling the operation of the robot that supports the processing head of the processing device according to processing steps stored in advance in the control device of the robot, the processing head of the processing device is moved to the workpiece. A control method for a robot that causes a processing head to perform work while moving along a processing line, and automatically stops the processing device when an abnormality occurs in the processing device during processing, the method comprising:
When it is detected that an abnormality has occurred in the processing device, the processing head of the processing device is moved to a position that is on the spatial movement path of the processing cycle before the abnormality occurrence and is a predetermined distance away from the workpiece during teaching. The machining head is moved back to a position determined as a teaching point taught by the machine and left on standby, and when restarting, the machining head is moved and returned to the machining start position of the machining cycle at the time of occurrence of the abnormality. .

[Effect]

According to the robot control method of the present invention, when an abnormality occurs in the processing device, the processing head of the processing device is
Since the machine is automatically retreated to the position on the spatial movement path of the machining cycle before the time of the abnormality and is kept on standby, maintenance can be performed immediately on the part where the machining equipment has experienced the abnormality, and the machining head can be moved when restarting. Since the machining head automatically returns to the machining start position of the machining cycle when the abnormality occurred, troublesome operation of the control device of the robot supporting the machining head is unnecessary.

〔Example〕

Next, a method for controlling a robot according to an embodiment of the present invention will be explained based on the drawings.

FIG. 1 shows a schematic diagram of an arc welding device and a robot to which the robot control method according to the present embodiment is applied, and FIG. 2 shows a processing flow showing the control method of the arc welding device robot according to the present embodiment. show.

First, in FIG. 1, reference numeral 1 denotes an arc welding robot, and the movements of the arms 3A to 3E are controlled by signals from a robot control device 2.

Further, reference numeral 4 indicates an arc welding device which is a processing device, and includes a welding torch 5 which is a processing head, and a welding torch 5 which is a processing head.
and a welding control device 6 that controls energization to. A welding wire 7 is fed through the center of the welding torch 5, and the welding wire 7 is connected to the welding control device 6 via a contact tip (not shown). Current is supplied.

Reference numeral 8.9 indicates a workpiece to be welded, and the welding torch 5 welds the welding line 10, which is the joint portion of the double-wave welded objects 8 and 9, while tracing the welding line 10.

Next, a processing flow related to the robot control method of this embodiment will be explained based on FIG. 2.

When the arc welding robot 1 shown in FIG. 1 is started, the control program is initialized in step 101 of the process flow shown in FIG. Move to the welding start point of the first cycle, which is the welding cycle.

After the robot has moved to the welding start point for the lth cycle, the process proceeds to step 103, where a welding start command signal is sent from the robot control device 2 to the welding control device 6, and the process proceeds to the next step 104.

At this step 104, the process remains in a standby state for about 0.5 to 1.0 seconds, and then proceeds to the next step 105.

During this time, arc start processing is performed in the arc welding device 4 in response to the welding start command signal. Eventually, after the above-mentioned time has elapsed, it is determined in step 105 whether or not an arc-on signal indicating that an arc has occurred is sent from the welding machine control device 6, and "YE" is determined.
When it is confirmed that S'', that is, an arc has occurred, the process proceeds to the next step 106, and the welding torch 5 is moved at a predetermined welding speed to the welding end position, which is the welding end position of the welding cycle.

When the welding torch 5 moves to the welding end position of the welding cycle and the welding of that cycle is completed, the process proceeds to step 107, where it is determined whether the current welding cycle is the final welding cycle, and "NQ II, that is, If it is not the final welding cycle, the process advances to step 108, where the cycle number N is increased by one, and the next welding cycle is executed according to the processing contents of steps 102 to 106 of the processing flow.

After repeating this series of steps and executing the final welding cycle, "YES" is determined in step 107 of the processing flow, and the process proceeds to the next step 109, where the welding torch 5 is returned to the origin, All series of welding cycles are completed.

By the way, on the other hand, a welding start error occurs in an arbitrary welding cycle, for example, the Nth welding cycle (for the sake of explanation, the starting point of this Nth welding cycle is assumed to be the mth point of the motion teaching points of the robot 1). In this case, the arc-on signal will not be transmitted from the welding machine control device 6 even after 0.5 to 1.0 seconds have elapsed after the welding start command signal was transmitted from the robot control device 2 to the welding machine control device 6. . In this case, the determination in step 105 is "NO", and the process proceeds to step 111 on the right side of the process flow to stop transmitting the welding start command signal to the welding machine control device 6 and cause the welding machine control device 6 to operate. At the same time, the control unit 100 issues a command to stop the control knob 112 and proceeds to the next step knob 112. Then, a welding start error alarm signal is transmitted, and an alarm lamp or an alarm buzzer (not shown) is activated.

At the same time, this is a feature of the present invention,
Proceeding to the next step 113, the welding torch 5 is moved between the previous welding cycle, that is, the previous (N-1)th cycle welding end position and the current Nth cycle welding start position W (the motion teaching point of the robot 1). a teaching point that is located on the spatial movement path between the m-th point of That is, the robot 1 is moved to the (m-1)th point of the motion teaching points. Then, the process proceeds to the next step 114, where a signal indicating "at the standby point" is transmitted, and the process proceeds to the next step 114, where the movement of the robot 1 is prohibited and the robot 1 is kept in a self-holding state.

As explained in step 112 above, when a welding start error occurs, the robot control device 1 sends a welding start error alarm signal and activates the alarm lamp, alarm buzzer, etc. (not shown). Due to the activation of the alarm device, the operator notices the occurrence of a welding start error and repairs the abnormal part of the arc welding device 4.

Then, when the repair is completed, the operator
When you press the error reset button, step 11 of the processing flow
6, the process proceeds to the next step 117 to stop the generation of the welding start error alarm signal, and in the next step 118, the arc welding line worker further presses the start button. If the result is "YES", the process proceeds to the next step knob 119, stops the transmission of the "standby point" signal, returns to the previous step 102 in the processing flow, and starts welding with the welding torch 5. The process returns to the welding start position of the welding cycle at the time when the mistake occurred.Then, the welding operation starts again from step 103 and is executed until the last welding cycle.

As described above, in this embodiment, when a welding start error occurs, the welding torch 5 is located on the spatial movement path of the welding cycle preceding the current welding cycle, and is located on the workpiece 8.9. Since the robot 1 is moved to a predetermined distance from the robot 1 and placed on standby, the operator does not have to operate a teaching box (not shown) to make the robot 1 wait at a predetermined position. Repairs of abnormal parts of the welding device 4 can be performed extremely smoothly.

In addition, after the repair is completed, the welding torch 5 is automatically returned to the welding start position of the welding cycle at the time when the welding start error occurred by the operator's startup operation, and the welding cycle is executed again. Therefore, as mentioned above, there is no need for the operator to operate the robot 1 and return the welding torch 5 to the welding starting position, which makes it possible to repair abnormal areas in a short time. Moreover, it can be performed without requiring any skill in robot operation.

〔Effect of the invention〕

As described above, according to the present invention, when an abnormality occurs in a processing device, the robot supporting the processing head of the processing device does not immediately stop on the spot, and the processing head is moved at the time when the abnormality occurs. The machine is automatically moved back to a position on the spatial movement path of the previous machining cycle and a predetermined distance away from the workpiece, and is then put on standby, and restarted after the abnormality has been repaired. When the machine is activated, the machining head is automatically returned to the machining start position of the machining cycle at the time of the abnormality occurrence, which greatly improves the workability of maintenance when an abnormality occurs, and also increases the ability to operate the robot. This has an excellent effect in that the processing equipment can be sufficiently maintained in the event of an abnormality even if it is not carried out.

Furthermore, since maintenance can be carried out in an extremely short time, the processing line can be stopped for only a short time, resulting in a significant improvement in productivity.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram of an arc welding device to which a robot control method according to an embodiment of the present invention is applied, and a robot for this arc welding device, and Fig. 2 is a schematic diagram of a robot for this arc welding device, which also relates to an embodiment of the present invention. 3 is a flowchart of a processing flow showing a method of controlling a robot. FIG. 3 is a process flow showing a conventional example of a robot control method, and FIG. 4 is a diagram around a welding torch of an arc welding device, which is an example of a processing device. 1-1-, Robot 2...Robot control device (control device) 4...
Arc welding equipment (processing equipment) 5 ... Welding torch (
Processing head) 8.9 ... Workpiece to be welded (workpiece) 1
0...Welding line (processing line) Fig. 1 Fig. 3

Claims (1)

[Claims] By controlling the operation of the robot supporting the processing head of the processing device according to processing steps stored in advance in the control device of the robot, the processing head of the processing device is moved along the processing line of the workpiece. In addition, when an abnormality occurs in the processing device during processing, the processing head is automatically moved by detecting the occurrence of the abnormality in the processing device and automatically controlling the processing device and the robot. A control method for a robot that stops the robot at a certain time, wherein when an abnormality is detected in the processing device, the processing head of the processing device is stopped on a spatial movement path in a processing cycle before the abnormality occurs, and During teaching, the machining head is moved to a predetermined teaching point that is a predetermined distance away from the workpiece and is kept on standby, and when restarting, the machining head is moved to a position that is a predetermined distance away from the workpiece and is placed on standby. A method for controlling a robot, characterized in that the robot is moved and returned to a starting position.