JPS6238780A - Deposition detecting method in spot welding robot - Google Patents

Abstract

PURPOSE:To eliminate the delay in welding work due to emergency stoppage and the bad working efficiency by constituting to send an emergency stop signal to the robot as a deposition error only in the case of the second timer having still constant even after the timer-up. CONSTITUTION:Two timers TIM 1, TIM 2 are used and the time-up time of one part of the timer TIM 1 is set shorter. In case of the time-up of the TIM 1 the presence or absence of the contact of the tip and work is detected by the detecting means. In case of the welding burrs contact with the tip being detected the welding robot continues the waiting while under the motion of the TIM 2 and the welding gun opens completely from the work for the while. In case of the contact of the tip and burr coming of until the decision as to whether the TIM 2 was up or not is made the robot starts the movement to the following step instantaneously. On the other hand in case of the contact of the tip and work being detecting even after the time of the TIM 2 being up it is regarded as deposition and the robot is subjected to emergency stoppage.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for detecting welding in a spot welding robot.

(Prior Art) Conventionally, in a spot welding robot placed on a work line in a factory, the welding gun of the robot and the workpiece may become welded together during the work.

If such a welding error occurs, if you send the spot welding completion signal and move the robot to the next step, there is a risk that the machine will be destroyed. It was necessary to take measures.

In consideration of such a situation, conventionally, a welding detection method as shown in FIG. 4, for example, has been adopted.

That is, in FIG. 4, when spot welding starts (step 51), a flag is set during welding (step 52).
While the flag is fully set, contact between the welding gun tip and the workpiece should not be detected. When spot welding is completed (step 53), the flag is reset (step 54) and the timer is started (step 5).
5). While this timer is operating, contact between the tip of the welding gun and the workpiece is not detected by the detection means, and the robot continues to stand by at its original position. The timer is tight, up (
By doing step 56), the detection means detects whether or not the tip and the workpiece are in contact (step 57). If the contact between the tip and the workpiece is not detected, the robot moves to the next step. Start moving to the position (step 58). On the other hand, if contact between the chip and the workpiece is detected, this is considered a welding error and the robot is brought to an emergency stop (step 59).

(Problem to be solved by the invention) In the conventional welding detection method as described above, if the timer setting time is too short, the spot welding gun of the robot opens from the workpiece (the tip separates from the workpiece). )
During the process, contact between the tip and the workpiece is detected, and there is a problem in that contact between the tip and the welding point on the workpiece is detected, and the robot has to make an emergency stop very frequently due to the welding point. Ta. On the other hand, if the timer is set longer, contact will not be detected until the welding gun is completely separated from the workpiece, and the frequency of emergency stops due to contact between the welding tip and the tip will be reduced. However, the longer the timer is set, the longer the robot will have to wait at all the spots where spot welding is to be performed, resulting in a longer overall working time and lower work efficiency. .

(Means for Solving the Problems) The present invention has been devised in view of the above-mentioned conventional problems, and is capable of avoiding and preventing emergency stops of robots due to welding chips, and of preventing spot welding by spot welding robots. The purpose is to provide a welding detection method that can improve work efficiency, and its gist is to detect contact between a welding tip and a workpiece, etc. in a spot welding robot and to make an emergency stop of the robot. , comprising a first timer and a second timer that start operating after the spot welding work is completed, the time-up time of the second timer is set longer than the time-up time of the first timer,
After the first timer times up, the detection means detects the contact between the welding tip and the workpiece, and if there is no contact, the robot moves to the next step, and if there is contact, the second timer starts again after the timer times up. The structure is configured so that only when there is contact, an emergency stop signal is sent to the robot as a welding error.

(Function) Since the time-up time of the first timer is short, time-up occurs while the welding gun is being opened, and contact between the tip and the workpiece can be detected at that stage. If there is no welding between the tip and the workpiece and no welding cracks have occurred on the workpiece, contact between the tip and the workpiece is not detected and the robot immediately starts moving to the next step position. Additionally, if a welding splinter has occurred and the welding splint is in contact with the tip, the robot will not come to an emergency stop until the second timer times up, and the welding gun will open further during that time. , when the contact between the welding pad and the tip is broken, the robot starts moving to the next step position. Second
The robot is brought to an emergency stop only if there is still contact between the tip and the workpiece after the timer times out, that is, if the tip and the workpiece are in a welded state.

(Example) Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a flowchart showing the first embodiment. In the figure, TIMI is a gun wait timer, and after the spot welding robot completes welding work at a certain welding point, the spot welding robot moves to the next step position (welding point). This is a timer for setting the waiting time until the movement starts. Also, TIM in the figure
2 is a welding ignore timer for setting a certain period of time after the completion of welding work in which contact between the tip of the welding gun and the workpiece is not detected.

Note that in this example, TIMI is set to about 0.1 to 0.3 seconds. This setting time is after the completion of spot welding.
This is the minimum time during which the welding gun opens slightly relative to the workpiece (the welding tip slightly separates from the workpiece).

Further, 71M2 is set to about 3 to 5 seconds. This set time is longer than the time required for the welding gun to fully open relative to the workpiece after spot welding is completed.

To explain the flowchart here, when the spot welding robot closes the welding gun at a certain step position (dot point) and starts spot welding on the workpiece (step 1), the welding flag is set ( Step 2)
. While the flag is set, contact (welding) between the tip of the welding gun and the workpiece is not detected by the detection means. Next, it is determined whether spot welding has been completed (step 3), and if it has not been completed, welding is continued, and if completion is confirmed, the welding flag is reset (step 4). At the same time as the welding flag is reset, the timers of TIMI and 71M2 start (step 5). While TIMI and 71M2 are operating, the robot waits at its original position and does not detect contact between the tip and the workpiece. Also, during TIMI operation, the welding gun opens slightly with respect to the workpiece (the tip slightly separates from the workpiece). Next, it is determined whether TIMI has timed up (step 6), and TIMI
When the time has elapsed, the presence or absence of contact between the tip and the workpiece is detected by the detection means (step 7). If the tip and workpiece are not welded and the welding edge and tip are not in contact, contact is not detected and the spot welding robot starts moving to the next step using the moving means ( Step 8). On the other hand, if contact between the welding tip and the tip is detected, conventionally the robot would have to make an emergency stop due to a welding error, but in this example, the welding robot will remain on standby while the 71M2 is operating. Continue,
During this time, the welding gun opens completely above the workpiece. If the contact between the tip and the welding pad is broken before 71M2 determines whether the time has expired (step 9), the robot will immediately start moving to the next step (
Step 8). On the other hand, if the contact between the chip and the workpiece is still detected even when 71M2 times out, it is assumed that welding has occurred, and the robot is brought to an emergency stop (step 10) as a welding knife. In this case, an emergency stop and a warning may be issued. In addition, even after the robot starts moving to the next step using the moving means (step 8), for safety reasons, contact is detected (step 13), and if there is contact with the chip, an emergency stop is performed (step 10). Ru.

In this way, the welding detection method of this example uses two timers (TIMI, 71M2) with different set times, and by setting the time-up time of one of the timers TIMI to a short time, it is possible to prevent welding from occurring. If contact with the chip is not detected, the robot can immediately move to the next step, making it possible to extremely shorten the robot's waiting time. In addition, only when contact between the welding pad and the chip is detected, the robot is made to wait until the time of the other timer TIM2 has expired, and the robot is brought to an emergency stop only if there is still contact even after the time of 71M2 has expired. Therefore, by the time-up of 71M2, the welding gun is completely separated from the workpiece, and the contact between the welding pad and the tip is often lost, and the frequency of emergency stop of the robot is extremely reduced. That is, if the welding pad contacts the tip for a short time, it will not be detected as a welding error and an emergency stop will not occur. Therefore, the overall speed of welding work by the robot is increased and work efficiency is improved.

Next, a second embodiment of the present invention will be described with reference to FIGS. 2 and 3.

In this example, a detection procedure using TIM3 is added after the procedure of step 8 in the first embodiment. That is, in addition to the timers TIMI and TIM2 in the first embodiment, a new timer TIM3 is set.

To explain the flow based on the chart in Figure 2, if contact between the chip and the workpiece is not detected and the robot starts moving to the next step (step 8), the TIM3 starts (step 11).

This timer TIM3 does not detect and ignore contact between the welding pad and the tip during the operating time until the timer times up. While TIM3 is in operation, the robot continues to move toward the next step, and when TIM3 times up (step 12), the presence or absence of contact between the welding pad and the tip is detected (step 13). If there is no contact, the robot restricts its movement (step 14). On the other hand, if contact is successfully detected, the robot is brought to an emergency stop (step 10).

That is, at the time when the contact between the welding tip and the tip is detected in step 7 according to the method of the first embodiment, the welding gun is only slightly opened with respect to the workpiece because the TIMI setting time is short. , when the robot starts moving towards the next step (step 8),
As shown in Fig. 3, the tip T of the welding gun may come into contact with the welding pad B on the workpiece made in the direction G of the robot's movement (step 13), and in such a case, the robot may Emergency stop (step 1)
0) Possible. However, in this example, while TIM3 is in operation, the contact between welding pad B and tip T is not detected and ignored, so if the robot moves out of this contact area before TIM3 times up, the robot will be able to make an emergency stop. This will occur less frequently.

In this way, with the method in this example, an emergency stop is not required even for burrs B that occur in the direction of movement of the robot, and the frequency with which an emergency stop is required is further reduced than in the first embodiment, improving work efficiency. I can make it.

(Effects of the Invention) As is clear from the above description, the present invention provides a detection method for detecting contact between a welding tip and a workpiece in a spot welding robot and causing the robot to come to an emergency stop.
It is equipped with a first timer and a second timer that start operating after the spot welding work is completed, the time-up time of the second timer is set longer than the time-up time of the first timer, and the time-up time of the first timer is set to be longer than the time-up time of the first timer. Later, a detection means detects contact between the welding tip and the workpiece, and if there is no contact, the robot is moved to the next step, and if there is contact, a second timer is activated to detect if there is still contact after time-up. Since the configuration is configured to send an emergency stop signal to the robot only as a welding error, even if the welding gun tip that occurs on the workpiece comes into contact with the welding gun tip during spot welding work by the spot welding robot, the contact will be temporary. If this were the case, the robot would not have to make an emergency stop, and it would be possible to avoid the conventional situation where the robot would have to make an emergency stop frequently due to welding. Therefore, it is possible to eliminate delays in welding work and poor work efficiency caused by emergency stops, and the robot can be activated only for welding between the welding tip and workpiece that truly requires an emergency stop, or for extremely large welding defects. This produces the effect that it can be stopped.

[Brief explanation of the drawing]

FIG. 1 is a flow chart diagram showing a first embodiment of the present invention;
FIG. 2 is a flowchart showing the second embodiment, FIG. 3 is an explanatory diagram showing the relationship between the welding pad and the chip, and FIG. 4 is a flowchart showing the conventional example. ■~0...Step T...Bacillary tip B...Welding paris

Claims (2)

[Claims] (1) A detection method that detects contact between a welding tip and a workpiece, etc. in a spot welding robot and makes an emergency stop of the robot, which includes a first timer and a second timer that start operating after spot welding work is completed. The time-up time of the second timer is set longer than the time-up time of the first timer, and after the time-up of the first timer, the detection means detects contact between the welding tip and the workpiece, and the contact is detected. If there is no contact, the robot moves to the next step, and if there is contact, the second timer is configured to send an emergency stop signal to the robot as a welding error only if there is still contact after the time has elapsed. A method for detecting welding in a spot welding robot characterized by: (2) A third timer is provided, which starts operating when the welding tip and the workpiece do not come into contact after the time of the first timer expires and the robot starts moving to the next step, It is characterized by a structure that detects contact between the welding tip and the workpiece after uploading, and if there is no contact, the robot continues moving, and if there is contact, an emergency stop signal is sent to the robot as a welding error. A method for detecting welding in a spot welding robot according to claim 1.