JP5040125B2 - Laser welding method and apparatus - Google Patents

Description

  The present invention relates to a laser welding method and apparatus for starting and stopping a laser oscillator at a timing that matches a robot hand when the robot hand reaches the start or end of a pre-programmed laser irradiation position and performing welding using laser light. .

  Generally, when welding an inner plate member and an outer plate member of an automobile body (body), a resistance spot welding robot is used. However, in this resistance spot welding robot, the work is performed by bringing the welding tip constituting the welding gun into contact with the body. For this reason, there is a limit to speeding up the welding work.

  Thus, conventionally, a remote laser welding method has been proposed in which welding is performed using a laser beam from a location away from the welding site (see Patent Document 1 below).

  In this prior art, an optical head that emits laser light for welding is attached to a robot hand, and this is connected to a laser oscillator with an optical fiber, and the laser light is shaped into the shape of the welded part inside the optical head. Built-in optical deflection optical system (scanner) that scans along. Then, under the control of the robot controller, the laser hand is moved so as to pass in the vicinity of the welding site, and the light deflection optical system of the optical head is actuated to displace the laser beam emission angle. Scan the light to perform the desired welding operation. According to this remote laser welding method, linear seam welding can be performed, and a welding operation can be performed at a high speed while moving the robot hand to a plurality of intermittently existing welding sites.

  However, since the robot controller and the laser oscillator are separate from each other in the above configuration, some communication means such as serial communication or I / O processing is required to instruct the start or stop timing of the laser oscillator. . For this reason, time required for serial communication and I / O processing is required, and there is a deviation in the start or stop timing of the laser oscillator that needs to be controlled in ms units.

  For example, when connected by serial communication, (1) time required for the CPU of the robot controller to perform communication processing, (2) time required for actual signal transmission, (3) laser oscillator The loss time of polling being performed, (4) actual reception time, (5) processing time of received data, and the like are required. As a result, delay and variation of about several ms to several tens of ms occur. . Of course, if some high-speed protocols are used, this time can be processed within 1 ms. However, not all commercially available robot systems are compatible, and it is constructed as a general-purpose device. Since this is not possible, the number of devices increases, resulting in complicated facilities and difficult maintenance.

  Considering the case where processing is performed using an I / O interface provided in all robot systems, the following is considered. That is, when the robot controller recognizes that it is at the laser oscillation point and tries to output a laser oscillator start command through the I / O interface in the controller, the state of the I / O interface is refreshed (updated) for a predetermined time. Since the processing is adopted, the output timing is shifted by the maximum I / O refresh interval. Actually, it is often an I / O refresh interval of about 8 ms to 10 ms, so depending on the moving speed of the robot, for example, if the I / O refresh interval is 8 ms and the moving speed of the robot is 600 mm / s, the maximum A welding position deviation of 6 mm will occur, and this deviation amount will vary further each time.

Similarly, the laser OFF timing at which the laser oscillator drops the output below the welding level in response to a stop command also causes a deviation that maximizes the I / O refresh interval, and forms an undesired weld bead. I'm stuck.
JP 2005-177862 A

  The present invention has been made to solve the above-described problems, and its object is to compensate for a signal delay caused by an I / O interface interposed between a robot controller and a laser oscillator. When the robot hand comes to the start or end of the laser irradiation position, the laser oscillator is started or stopped at a timing that matches this.

  Another object of the present invention is to eliminate a deviation in laser irradiation timing due to a delay in the rise of the laser oscillator itself.

In order to achieve such an object, in the present invention, a welding optical head connected to a laser oscillator is mounted on a robot hand, and the robot hand is moved at a pre-programmed laser irradiation position of the robot hand. In a laser welding method in which a laser oscillator is activated through an I / O interface and welding is performed with a laser beam, on the time axis at which the robot hand reaches the start end of the laser irradiation position based on current position information of the moving robot hand It predicts the welding start position, and calculates the shift amount on the time axis from the I / O refresh timing that will be generated immediately before the welding start position to the predicted welding start position as the laser starting timing value, the laser activation A timing value is provided to the laser oscillator.

  In the present invention, the laser output delay time from when the laser oscillator receives the oscillation start command until the laser oscillator output reaches a predetermined welding start level at which welding can be performed is calculated, and the calculated laser output delay time is Compensate for the timing shift of the entire system in consideration of the shift amount.

  In the present invention, based on the current position information of the moving robot hand, the welding end position on the time axis at which the robot hand reaches the end of the laser irradiation position is predicted, and the first calculation time that comes after the current time is calculated. A deviation amount on the time axis from the I / O refresh timing to the predicted welding end position is calculated as a timing value, and the timing value is given to the laser oscillator.

  In the present invention, the deviation of the irradiation start timing or irradiation end timing of the laser light due to the I / O interface is compensated, and when the irradiation position of the robot hand comes to the start or end of the seam welding site, this is accurately detected. The laser oscillator is started or stopped at a timing that matches the above. Therefore, according to the present invention, laser welding can be performed at a high speed while moving the robot hand without the actual laser irradiation position deviating from the seam welding site.

  Further, according to the present invention, it is possible to obtain a precise laser irradiation timing as a whole system by eliminating the delay of the rise of the laser oscillator itself.

  Embodiments according to the present invention will be described below with reference to the drawings.

<First Embodiment>
FIG. 1 is a block diagram showing an outline of a laser welding apparatus according to an embodiment of the present invention. This laser welding apparatus includes an optical head 2 attached to the tip of a robot hand 1, and this optical head 2 is connected to a laser oscillator 4 by an optical fiber cable 3, and welding laser light from the optical head 2. Is emitted. An optical deflection optical system (scanner) is provided inside the optical head 2 as necessary.

  The robot hand 1 is a robot hand driven by a known motor 5 such as a 6-axis motor, and a robot controller 6 is provided as a control system for the robot hand 1. The laser oscillator 4 is provided with a laser output control system 7 for controlling the laser start oscillation, and is connected to the robot controller 6 via the I / O unit 8.

  The robot controller 6 includes a motor controller 10 that moves the robot hand 1 to a pre-programmed laser irradiation position while receiving the current position information of the robot hand 1 from an encoder 9 attached to the motor 5. The robot controller 6 also has a laser control unit 11 that instructs the laser output control system 7 of the laser oscillator 4 to start or stop the laser oscillator 4. In order to regulate these controls, the I / O unit 8 has a refresh cycle signal generation means 12 inside, and generates a refresh timing T about every 8 ms. With this refresh timing T, the contents of the motor control unit 10 and the I / O unit 8 of the robot controller 6 are updated, and the position of the robot hand 1 and the irradiation timing of the laser beam are updated.

  In the case of only the above configuration, the welding operation is as follows. In FIG. 2, (a) shows the position on the time axis through which the robot hand 1 passes from the start end to the end of the laser irradiation position programmed in advance, that is, from the welding start position P1 to the welding end position P2. FIG. 2B shows the timing of the I / O refresh cycle signal. In synchronization with the I / O refresh timing T, the laser oscillator 4 is started (ON) or stopped (OFF) as shown in FIG. The welding start position P1 or the welding end position P2 occurs at any time within the interval of the I / O refresh timing T. For this reason, as shown in FIG. 2C, the time (laser start timing, laser stop timing) at which the laser oscillator 4 is started or stopped is only the time length α1 or α2 from the welding start position P1 or the welding end position P2. It will shift.

  Therefore, as shown in FIG. 1, welding start / end position prediction means 13, timing value calculation means 14, and timing value determination means 15 are added to the laser controller 11 of the robot controller 6. These function as follows with respect to the start and end of welding. FIG. 3 shows the principle of adjusting the output timing.

  Regarding the start of welding, first, the welding start / end position prediction means 13 reads a laser irradiation position (welding part) programmed in advance by the robot hand 1, and based on the current position information of the moving robot hand 1, the robot A welding start position P1 (see FIG. 3A) on the time axis at which the hand 1 reaches the start end of the pre-programmed laser irradiation position is predicted. Specifically, as shown in FIG. 3 (c), the robot hand 1 is placed at the start of the pre-programmed laser irradiation position by the second I / O refresh timing T2 that comes after the current time t0. A position on the time axis to be reached is predicted as a welding start position P1. These functions are obtained by constructing the control logic of the robot controller 6 with an observer (logical control model) and calculating the position of the robot hand 1 every moment.

  Next, the timing value calculating means 14 from the first I / O refresh timing T1 (see FIG. 3B) generated immediately before the welding start position P1 to the predicted welding start position. The amount of deviation α1 (time length) on the time axis is calculated as the laser activation timing value Ts. Then, the laser activation timing value Ts is given to the laser output control system 7 of the laser oscillator 4 through the timing value determining means 15 and the I / O unit 8, thereby irradiating the laser oscillator 4 with the I / O interface interposed. Compensate for deviations in start timing.

  On the other hand, regarding the end of welding, first, the welding start / end position predicting means 13 takes time for the robot hand 1 to reach the end of the pre-programmed laser irradiation position based on the current position information of the moving robot hand 1. A welding end position P2 on the shaft (see FIG. 3A) is predicted. Specifically, as shown in FIG. 3C, the robot hand 1 is placed at the end of the pre-programmed laser irradiation position by the second I / O refresh timing T2 in the calculation that comes after the current time t0. A position on the time axis to be reached is predicted as a welding end position P2. These functions can be obtained by calculating the position where the robot hand 1 should be from time to time using an observer (logical control model) built on the control logic of the robot controller 6.

  Next, the timing value calculation means 14 calculates the predicted welding end position P2 from the first calculated I / O refresh timing T1 (see FIG. 3B) generated immediately before the welding end position P2. The amount of deviation α2 (time length) on the time axis until is calculated as the laser stop timing value Te. Then, the laser stop timing value Te is given to the laser output control system 7 of the laser oscillator 4 through the timing value determining means 15 and the I / O interface, so that the irradiation of the laser oscillator 4 due to the intervening I / O interface is completed. Compensate for timing gaps.

<Second Embodiment>
FIG. 4 shows an output pattern of the laser oscillator 4. The laser oscillator 4 is normally at an output level L1 in an excited state, and after receiving a laser activation command at time t1, the output once decreases to zero, and then the output increases according to a slope determined by parameters in the oscillator. go. Then, it reaches a predetermined welding start level (threshold value) L2 that can be welded at time t2, and then further increases to a desired output level L3.

  Therefore, after the laser oscillator 4 receives the oscillation start command, the laser output on the laser oscillator 4 side indicated by the times t1 to t2 until the output of the laser oscillator 4 rises to the welding start output level L2 indicated by the dotted line in FIG. A delay time Δt is generated. Therefore, in the second embodiment, the laser output delay time Δt of the laser oscillator 4 is introduced into the laser activation timing processing logic by the robot controller 6, and all the delays of the related control devices are compensated in a control manner.

  Specifically, as shown in FIG. 1, means for calculating a laser output delay time Δt from when the laser oscillator 4 receives an oscillation start command until the output of the laser oscillator 4 reaches a predetermined welding start level at which welding is possible. (Laser output delay time calculating means 16) is provided, and the calculated laser output delay time Δt is sent to the timing value determining means 15, where it is added to the amount of deviation so that the timing deviation of the entire system can be reduced. To compensate.

  This will be described with reference to FIG. 5. First, the welding start / end position predicting means 13 has a welding start position P1 on the time axis at which the robot hand 1 reaches the start end of the pre-programmed laser irradiation position (see FIG. 5A). ). Specifically, as shown in FIG. 5C, the robot hand 1 is placed at the start of the pre-programmed laser irradiation position by the second I / O refresh timing T2 in the calculation that comes after the current time t0. A position on the time axis to be reached is predicted as a welding start position P1.

  Next, the timing value calculation means 14 from the first calculation I / O refresh timing T1 (see FIG. 5B) generated immediately before the welding start position P1 to the predicted welding start position. Is calculated as a timing value Ts. Then, the timing value determining means 15 gives this timing value Ts to the laser output control system 7 of the laser oscillator 4 to compensate for the deviation of the irradiation start timing of the laser oscillator 4 due to the intervening I / O interface. At this time, the timing value determination means 15 also receives the laser output delay time Δt calculated by the laser output delay time calculation means 16 and adds (subtracts) it to the timing value Ts to advance the laser oscillation timing by Δt. The adjusted timing value Ts1 is output to compensate for the timing shift of the entire system.

<Specific example 1>
Specific example 1 of the first embodiment will be described. FIG. 6 is a schematic diagram showing the configuration of the laser welding apparatus of the first specific example, and FIGS. 7 and 8 are diagrams showing the timing adjustment processing of the oscillation start command / stop command at the time of laser welding.

  As shown in FIG. 6, an observer 17 (logical control model) is incorporated on the control logic of the robot controller 6. The observer 17 is an existing technology as disclosed in JP-A-5-122970 (motor control device).

  In FIG. 6, the motor control unit 10 of the robot controller 6 includes a servo calculation unit 18. The laser control unit 11 includes, as constituent elements of the welding start / end position prediction means 13, a robot hand position estimation calculation unit 20 at a designated timing preceded by a feedforward calculation unit 19, and the estimated robot hand 1. It has the determination part 21 which determines whether the position of comes to a welding start position or a welding end position. In addition, the laser control unit 11 includes a timing value calculation unit 14 that calculates a timing value that accurately matches the arrival of the welding start position or the welding end position in consideration of the delay caused by the I / O interface. Have. In the case of this specific example 1, the timing value determining means 15 is not particularly provided.

  With reference to FIG. 7, the timing adjustment processing of the oscillation start command at the time of laser welding will be described.

  (1) First, an observer 17 (logical control model) built on the control logic of the robot controller 6 is used to calculate the position of the robot hand 1 every moment.

  (2) Capture the I / O processing refresh cycle signal in the robot controller 6, and reach the programmed welding start position P1 by the I / O refresh twice after the current time (for example, every 8 ms) Is determined by the determination logic incorporated in the control logic.

  That is, in the flow of FIG. 7, the position estimation calculation unit 20 first reads the robot program, thereby reading the programmed welding start position P1 from the contents of the laser welding command (step S1). Next, the position estimation calculation unit 20 takes in the I / O refresh timing from the refresh cycle signal generation means 12 (step S2), calculates the I / O refresh timing T2 after two times (step S3), and this I / O The estimated position of the robot hand 1 at the O refresh timing T2 is calculated (step S4). And the determination part 21 determines whether it passes the welding start position P1 regarding the estimated position of this robot hand 1 (step S2-S5).

  When the welding start position P1 is passed (YES in step S5), it is predicted that the welding start position P1 will arrive between the current time and the I / O refresh timing T2 (see FIG. 3) two times later. Become.

  (3) When the determination unit 21 determines that the robot hand 1 reaches the welding start position P1, the timing value calculation unit 14 determines that the laser activation imging Ts from the I / O refresh timing T1 one time after the current time. Is calculated. That is, the deviation α1 (time length) on the time axis from the calculated first I / O refresh timing T1 generated immediately before the welding start position P1 to the predicted welding start position P1 is set as the laser start timing. It calculates as value Ts (refer FIG. 3). This timing value Ts is a value of 0 ms at the minimum and 8 ms at the maximum because the I / O refresh timing occurs at intervals of 8 ms.

  Describing according to the flow of FIG. 7, the timing value calculating means 14 calculates the I / O refresh timing T1 after one time (step S6), and the observer 17 calculates the laser activation timing Ts from the refresh timing T1. (Step S7).

  (4) The calculated laser activation timing value Ts (time length) is decoded into 3 bits (or 4 bits) in the I / O signal (step S8), and the decoded information is output to the I / O unit 8 ( Step S9).

  The laser output control system 7 of the laser oscillator 4 receives the decoded laser activation timing value Ts, activates the laser oscillator 4 at this timing, and starts laser welding. If the predetermined laser welding is not performed (NO in step S10), for example, a forced stop process is performed as the abnormality process (step S11). If laser welding is normally performed (YES in step S10), the output to the I / O unit 8 is cleared and the process is terminated (step S12).

  (5) Next, with reference to FIG. 8, the adjustment processing of the oscillation stop command timing (laser stop timing) during laser welding will be described.

  In step S21 of FIG. 8, the position estimation calculation unit 20 reads the welding end position P2 programmed from the content of the laser welding command by prefetching the robot program (step S21). Next, the position estimation calculation unit 20 takes in the I / O refresh timing from the refresh cycle signal generation means 12 (step S22), calculates the I / O refresh timing T2 after two times (step S23), and this I / O The estimated position of the robot hand 1 at the O refresh timing T2 is calculated (step S24). Then, the determination unit 21 determines whether or not the robot hand 1 passes the welding end position P2 (steps S22 to S25).

  When the determination unit 21 determines that the robot hand 1 reaches the welding end position P2 (YES in step S25), the timing value calculation unit 14 calculates the I / O refresh timing T1 after one time (step S25). In step S26, the observer 17 calculates a deviation (time length) α2 on the time axis from the refresh timing T1 to the welding end position as a timing value (laser stop timing Te) (step S27).

  The calculated laser stop timing Te (time length) is decoded into 3 bits (or 4 bits) in the I / O signal (step S28), and the decoded information is output to the I / O unit 8 (step S29).

  The laser output control system 7 of the laser oscillator 4 receives the decoded laser stop timing Te. At this timing, the laser oscillator 4 stops and the laser welding is finished. When laser welding is not normally completed (NO in step S30), for example, a forced stop process is performed as an abnormal process (step S31). When the laser welding is normally finished (YES in step S30), the output to the I / O unit 8 is cleared and the process is finished (step S32).

  The advantage of the laser welding apparatus configured as described above is that only the control logic is added to the robot controller 6, and the deviation of the laser start timing, which has been a problem of the conventional system, without adding new components as a hard wafer. It is to be able to eliminate.

<Specific example 2>
Specific example 2 of the second embodiment will be described. FIG. 9 is a schematic diagram showing the configuration of the laser welding apparatus of the second specific example, and FIG. 10 is a diagram showing the timing adjustment processing of the oscillation start command at the time of laser welding.

  The laser welding apparatus of the second specific example is a specific example in that the robot controller 6 has a delay correction unit 22 as the laser output delay time calculating unit 16 in addition to the laser control unit 11 and the I / O unit 8. 1 and the laser welding apparatus. The delay correction unit 22 uses welding parameter data 23 prepared in advance in the robot controller 6 such as welding machine data such as a zero level return time, which is a setting parameter of the laser oscillator 4, and welding such as inclination and output value when the output increases. A parameter table reading unit 24 for reading data, a zero level return time reading unit 25 for reading the zero level return time from when the laser oscillator 4 receives the oscillation start command until the output once reaches the zero level, and the output is once at the zero level. A welding start output arrival time calculation unit 26 that calculates the time from when the welding reaches the welding (welding) start level L2 (see FIG. 4), and an oscillator that calculates the amount of time correction by integrating these times. And a delay time integrating unit 27.

  Next, the operation of the laser welding apparatus of the specific example 2 will be described.

  (1) First, welding machine data such as a zero level return time, which is a setting parameter of the laser oscillator 4, and welding data such as an inclination and an output value when the output is increased are input to the robot program.

  (2) The parameter table reading unit 24 of the robot controller 6 confirms the parameters with reference to the parameter table 23 when there is a laser welding command (creates a dedicated command) in the reproduced program. This parameter recognizes the detailed setting data by reading a pre-registered pattern, but it is also possible to directly write the parameter value. That is, parameters may be registered in advance in the robot controller 6 or may be given to the robot program as parameters of a dedicated command for laser welding.

  (3) The zero level return time reading unit 25 of the robot controller 6 reads the above zero level return time (the processing time from laser excitation unique to zero output) from among these parameters. Further, the welding start output arrival time calculation unit 26 calculates a time (welding start output arrival time) from when the output once reaches the zero level until it reaches the welding (welding) start level L2 (see FIG. 4). The oscillator delay time integration unit 27 integrates the zero level return time and the welding start output arrival time, and outputs delay time Δt (from the laser start command to the welding (welding) start level L2) (see FIG. 4), and this is used as a temporal correction amount corresponding to the deviation in the output characteristics unique to the present laser oscillator.

  (4) This correction amount is input to the timing value calculation means 14 in the I / O processing deviation compensation logic in the laser controller 11. In response to this, the timing value calculation means 14 advances the timing of the transmission start command to the laser oscillator 4 by the correction amount. That is, a transmission start command is output ahead of time by the amount delayed by the laser oscillator 4, and the timing shift in the entire control system is compensated.

  FIG. 10 shows the procedure of timing adjustment processing for the delay of the laser oscillator 4 itself.

  In the flow of FIG. 10, the robot controller 6 first reads the robot program in advance, thereby reading the programmed welding start position P1 from the contents of the laser welding command and reading parameters from a command dedicated to laser welding (step S41). . Next, the parameter table reading unit 24 reads the contents of the parameter table 23 (step S42).

  The command dedicated to laser welding is added to the conventional program, and is composed of, for example, “[welding machine data] [welding data] [work data] [code information by I / O]” [] The number value of the parameter table 23 that has been set is input. Here, the work data and I / O decode information are fixed to the model, and are set separately as welding conditions.

As the parameter table 23, for example, the following parameter table is prepared in the robot controller 6. (A) As welding machine data, laser oscillator manufacturer, oscillator type (CO ₂ laser, etc.), maximum output of equipment, excitation output value, zero level recovery time. (B) As welding data, output value, inclination, welding (welding) start output, welding pattern (S-shape, circle, straight line, radius, length, etc.), welding speed. (C) As work data, material, plate pressure, clearance, allowable maximum welding speed. (D) I / O address information and the number of dedicated decode bits (3 to 4 bits) as code information in I / O.

  In this example, the parameters are read from the setting table. However, the parameters can be directly described in a laser welding dedicated command. In this case, for example, “[zero level recovery time] [output] [inclination] [welding (welding) start output] [welding pattern] [welding speed]”. Also in this case, the set number value of the parameter table 23 is entered in [].

  Next, the delay correction unit 22 calculates the delay time (zero level return time + welding start output arrival time) Δt (see FIG. 5) of the oscillator described above (step S43).

  Next, the position estimation calculation unit 20 takes in the I / O refresh timing from the refresh cycle signal generation means 12 (step S44), calculates the I / O refresh timing T2 after two times (step S45), and this I / O The estimated position of the robot hand 1 at the O refresh timing T2 is calculated (step S46). And the determination part 21 determines whether the welding start position P1 is passed regarding the estimated position of this robot hand 1 (steps S44-S47).

  When the robot hand 1 passes the welding start position P1 (YES in step S47), the timing value calculation means 14 calculates the I / O refresh timing T1 after one time (step S48), and this refresh is performed by the observer 17. A deviation amount α1 (time length) from the timing T1 is calculated as the laser activation timing Ts (step S49).

  Next, the above delay time Δt (zero level return time + welding start output arrival time) is added to (subtracted from) the shift amount α1 (time length) (step S50), and the timing value ts1 (FIG. 5) as the entire system. 5 (c)) is calculated.

  The calculated timing value Ts1 (time length) is decoded into 3 bits (or 4 bits) in the I / O signal (step S51), and the decoded information is output to the I / O unit 8 (step S52).

  Normally, the laser output control system 7 of the laser oscillator 4 receives the decoded timing value Ts, and at this timing, the laser oscillator 4 is activated and laser welding is started. When the predetermined laser welding is not performed (NO in step S53), for example, a stop process is performed as the abnormal process (step S54). If laser welding is normally performed (YES in step S53), the output to the I / O unit 8 is cleared and the process is terminated (step S55).

  As described above, the present invention focuses on the I / O system provided in all robot systems, and eliminates the timing delay of the laser oscillation start command and the stop command due to passing through the I / O system. For this reason, the processing capability as if the robot controller 6 and the laser oscillator 4 were integrated is realized. In addition, the rise delay of the output of the oscillator itself can be compensated for and the timing shift of the entire control system of the laser welding apparatus can be eliminated.

  The above embodiment has been described on the assumption that the optical head 2 is attached to the robot hand 1. The optical head 2 may be fixed in position, but in order to enable higher-speed laser welding, an optical deflection optical system (scanner) that scans the laser light along the shape of the welded portion is provided in the optical head 2. It is also possible to adopt a configuration in which welding is performed by tracing a target welding shape with a scanner. The reason for this is that in the present invention, it is only necessary to obtain a conclusion by calculating the start or stop timing of the laser oscillator while the robot hand is moving. As a result, the irradiation of the laser beam is not delayed at the laser irradiation position. This is because it only has to start.

It is a block diagram which shows the structure of the laser welding apparatus of this invention. It is a figure where it uses for description of the shift | offset | difference of the laser starting timing which arises in the conventional laser welding apparatus. In the laser welding apparatus which concerns on the 1st Embodiment of this invention, it is a figure where it uses for description of the principle which compensates each shift | offset | difference of a laser starting timing and a laser stop timing. In the 2nd Embodiment of this invention, it is a figure which shows the output characteristic of the laser oscillator itself assumed. In the 2nd Embodiment of this invention, it is a figure where it uses for description of the principle which compensates the output delay of laser oscillator itself. It is a block diagram which shows the specific example of the laser welding apparatus which concerns on the 1st Embodiment of this invention. It is a flowchart which shows the timing adjustment process of the oscillator starting command in the laser welding apparatus of FIG. It is a flowchart which shows the timing adjustment process of the oscillator stop command in the laser welding apparatus of FIG. It is a block diagram which shows the specific example of the laser welding apparatus which concerns on the 2nd Embodiment of this invention. It is a flowchart which shows the timing adjustment process which compensates the output delay of oscillator itself in the laser welding apparatus of FIG.

Explanation of symbols

1 Robot hand,
2 optical head,
3 Optical fiber cable,
4 Laser oscillator,
5 Motor,
6 Robot controller,
7 Laser output control system,
8 I / O units,
9 Encoder,
10 Motor controller,
11 Laser controller,
12 refresh cycle signal generating means,
13 welding start / end position prediction means,
14 timing value calculating means,
15 timing value determining means,
16 Laser output delay time calculating means,
17 Observer,
18 Servo calculation part,
19 Feedforward operation part,
20 position estimation calculation unit,
21 determination unit,
22 Correction part,
23 Parameter table
24 Parameter table reading section,
25 Zero level recovery time reading section,
26 welding start output arrival time calculation unit,
27 Oscillator delay time integration unit.

Claims (8)

An optical head for welding connected to the laser oscillator is mounted on the robot hand, and while moving the robot hand, the laser oscillator is activated through the I / O interface at the pre-programmed laser irradiation position of the robot hand, and the laser In the laser welding method for performing welding by light,
Based on the current position information of the moving robot hand, predict the welding start position on the time axis where the robot hand reaches the start of the laser irradiation position,
Calculating a shift amount on the time axis from the I / O refresh timing that will be generated immediately before the welding start position to the predicted welding start position as the laser starting timing value,
A laser welding method, wherein the laser start timing value is given to the laser oscillator. Calculate the laser output delay time from when the laser oscillator receives the oscillation start command until the laser oscillator output reaches a predetermined welding start level where welding is possible,
2. The laser welding method according to claim 1, wherein the calculated laser output delay time is added to the shift amount to compensate for the timing shift of the entire system. Based on the current position information of the moving robot hand, predict the welding end position on the time axis when the robot hand reaches the end of the laser irradiation position,
Calculating the amount of deviation on the time axis from the I / O refresh timing generated immediately before the welding end position to the predicted welding end position as a laser stop timing value;
The laser welding method according to claim 1, wherein the laser stop timing value is given to the laser oscillator. A laser oscillator for emitting a laser beam for welding from an optical head mounted on the robot hand, and controlling the movement of the robot hand to the laser irradiation position while taking in the position information of the robot hand, and also via the I / O interface In a laser welding apparatus having a robot controller that gives laser activation oscillation timing to a laser oscillator,
Means for predicting a welding start position on a time axis at which the robot controller reaches the start end of a pre-programmed laser irradiation position based on current position information of the moving robot hand;
It means for calculating a shift amount on the time axis from the I / O refresh timing that will be generated immediately before the welding start position to the predicted welding start position as the laser starting timing value,
Means for providing said laser start timing value to said laser oscillator. The means for calculating calculates the laser start timing value when the predicted welding start position arrives before the second calculation I / O refresh timing that comes after the current time. The laser welding apparatus according to claim 4. Means for calculating a laser output delay time from when the laser oscillator receives an oscillation start command until the output of the laser oscillator reaches a predetermined welding start level capable of welding;
6. The laser welding apparatus according to claim 4, further comprising a unit that compensates for the timing shift of the entire system by adding the calculated laser output delay time to the shift amount. Means for predicting the welding end position on the time axis at which the robot controller reaches the end of the pre-programmed laser irradiation position based on the current position information of the moving robot hand;
It means for calculating a shift amount on the time axis from the I / O refresh timing that will be generated immediately before the welding end position to the predicted welding end position as laser stop timing values,
The laser welding apparatus according to claim 4, further comprising: a unit that gives the laser stop timing value to the laser oscillator. The means for calculating calculates the laser stop timing value when the predicted welding end position arrives before the calculation second I / O refresh timing that comes after the current time. The laser welding apparatus according to claim 7.

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