JPH11277263A - Teaching method, laser welding method and laser welding apparatus in laser welding apparatus - Google Patents

Abstract

(57) [Summary] [Problem] To accurately position a focal point of a laser beam on a welded portion having a small width. A laser processing head attached to a robot.
Are driven up and down by the motor 6. At the time of teaching, the workpiece 21 (flange portions 31A, 31B) is pressed by the roller 21 disposed at a position shifted in the welding direction with respect to the processing head 3, and the measurement is performed by the measuring device 10 attached to the processing head 3. The robot 1 is moved along the work 31 with the child 10a in contact with the work 31. The vertical position of the work 31 corresponding to the robot position is output from the measuring device 10 and stored in the controller U. Laser welding is performed with the measuring device 10 removed from the processing head 3. At this time, the motor U is controlled by the controller U so as to compensate for the stored vertical displacement of the work 31 corresponding to the robot position, and the focal point of the laser beam is just positioned on the work 31. .

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a teaching method, a laser welding method, and a laser welding apparatus in a laser welding apparatus.

[0002]

2. Description of the Related Art Laser welding may be performed when welding a work, for example, when welding a sheet metal forming an automobile body. At the time of this laser welding, usually, a laser processing head for irradiating a laser beam is attached to the tip of the robot, and the robot moves the processing head along a welded portion of the work (for example, a flange portion of a sheet metal). Performed, the obtained welded portion becomes a linearly continuous line weld.

[0003] In the laser welding described above, it is necessary that the focal point of the laser beam be properly located at the welded portion.
If the focal position greatly deviates from the welded portion in the direction of the optical axis of the laser beam, it causes welding failure. JP-A-8-90
In Japanese Patent Publication No. 264, a pressing roller for pressing a welded portion is provided at the end of the robot, and laser welding is performed while pressing the vicinity of the focal point of the laser beam with the pressing roller. Regulate selfish movement,
There have been proposed ones that try to ensure that the focal point is properly positioned on the welded part. And press roller,
Disclosed are those that are displaced in the width direction (direction orthogonal to the welding direction) of the welded portion with respect to the processing head, that is, the focal position, and those that are displaced in the welding direction.

[0004]

As described in the above publication, when the pressing roller is shifted in the width direction of the portion to be welded,
The portion to be welded must be lengthened by the width of the pressing roller, which results in an increase in the width of the flange portion of the sheet metal serving as the portion to be welded, resulting in poor material yield.

If the pressing roller is displaced in the welding direction, the problem that the width of the portion to be welded becomes large as described above does not occur, but the position of the pressing roller and the focal position of the laser beam are welded. Due to the displacement in the direction, it often becomes difficult to accurately position the focal position on the welded portion. For example, when a sheet metal as a work has a curved surface, particularly when the sheet metal has a three-dimensional curved surface, elastic deformation of the sheet metal (spring back)
Accordingly, a situation in which the position of the laser beam in the optical axis direction is considerably different between the portion pressed by the pressing roller and the portion not pressed by the pressing roller is likely to occur.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to focus the laser beam on the welded portion without unnecessarily increasing the width of the work to be welded. It is an object of the present invention to provide a teaching method, a laser welding method, and a laser welding apparatus in a laser welding apparatus capable of properly positioning.

[0007]

In order to achieve the above object, in the present invention, the positioning of the laser processing head is basically performed using teaching. That is, in the teaching method in the laser welding apparatus according to the present invention, as described in claim 1, a laser processing head is provided at a tip portion of the robot, and a laser beam emitted from the processing head is provided. A teaching method in a laser welding apparatus that performs welding of a workpiece, wherein the processing head is provided so as to be displaceable in an optical axis direction thereof, and a driving unit that drives the processing head in the optical axis direction is provided. The processing head is provided with a measuring means for measuring a value relating to a distance between a focus position of the laser beam emitted from the processing head and the workpiece, and the measurement is performed by the measuring means while displacing the processing head in a welding direction by a robot. To obtain the measurement result by the measuring means corresponding to the robot position, and store the measurement result. . Preferred aspects of the teaching are as described in claims 2 and 3 in the claims.

According to the laser welding method of the present invention, a laser processing head is provided at the tip of the robot, and the workpiece is irradiated with laser light from the processing head. A laser welding method for performing welding, wherein the processing head is provided so as to be displaceable in the optical axis direction, and driving means for driving the processing head in the optical axis direction is provided. Measuring means for measuring a value related to the distance between the focus position of the laser light to be irradiated and the workpiece, and performing measurement by the measuring means while displacing the processing head in the welding direction by a robot, and A storage unit for storing a measurement result by the measurement unit is provided, and while controlling the driving unit in accordance with the stored value stored in the storage unit, the laser melting is performed. Perform, it is the way.

According to the laser welding apparatus of the present invention, a laser processing head is provided at the tip of the robot as described in claim 5 of the present invention. A laser welding apparatus for performing welding of the laser beam, wherein the processing head is provided so as to be displaceable in the optical axis direction, and driving means for driving the processing head in the optical axis direction is provided. Measuring means for measuring a value related to the distance between the focus position of the laser light to be irradiated and the workpiece, and performing measurement by the measuring means while displacing the processing head in the welding direction by a robot, and A storage means for storing a measurement result by the measurement means is provided, and a control means for controlling the driving means according to a stored value stored in the storage means. Are provided, it is so. A preferable mode on the premise of the above device is as described in claim 6 of the claims.

[0010]

According to the first aspect, the correspondence between the robot position and the focal position of the laser beam is stored by teaching, so that when the actual laser welding is performed after teaching, measurement by the measuring means is performed. By controlling the driving means using the stored values stored in accordance with the result, that is, adjusting the position of the processing head in the optical axis direction corresponding to the robot position, the focal position can be properly located at the portion to be welded. Since the measuring means used to obtain the stored value is provided in the processing head, the obtained measurement result, that is, the stored value also accurately corresponds to the focal position of the laser beam. Of course, the position adjustment of the processing head corresponding to the robot position, that is, the focus position adjustment is performed by the teaching, so that there is no problem even if the width of the welded portion is small.

According to the second aspect, by storing the amount of deviation from the focal position, the amount of adjustment from the basic position of the processing head can be easily obtained. Further, when the shift amount is within the predetermined allowable value range, it is not necessary to displace the processing head unnecessarily, so that the drive control of the processing head becomes easy.

According to the third aspect, the stored value obtained using the positioning of the portion to be welded using the pressing means is more accurate. Of course, since the pressing means is disposed at a position shifted in the welding direction with respect to the processing head, it is not necessary to increase the width of the portion to be welded with the provision of the pressing means.

According to the fourth aspect, laser welding using the teaching according to the first aspect is performed, and the laser beam is welded in a state where the focal point of the laser beam is properly set at the portion to be welded. can get.

According to a fifth aspect of the present invention, there is provided a laser welding method according to the fourth aspect, that is, a welding apparatus using the teaching according to the first aspect. According to the sixth aspect, the same effect as the effect corresponding to the third aspect can be obtained.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. 1, reference numeral 1 denotes a robot hand, and a base member 2 is fixed to the tip of the robot hand. A laser processing head 3 is held on the base member 2 via a slider 4 so as to be displaceable in the vertical direction (the optical axis direction of the laser beam). A bolt member 5 extending in the vertical direction is screwed into the slider 4, and the vertical position of the processing head 3 is adjusted by rotating the bolt member 5 forward and backward by a motor 6 as a driving unit. The vertical position of the processing head 3 with respect to the base member 2 is detected by an encoder 7 serving as a motor position detecting means.

The processing head 3 receives a laser beam from a laser beam generator (not shown) via an optical fiber and irradiates the laser beam downward. However, FIG. 1 shows a state at the time of teaching, and a differential transformer 10 as measuring means used at the time of teaching is located at a portion corresponding to the laser light to be irradiated. That is, as shown in FIG. 2, the laser beam R can be emitted from the tip of the processing head 3 as shown by a dashed line in FIG. 2. The transformer 10 is detachably mounted by using a screw. When the differential transformer is mounted, irradiation of laser light is not performed. In FIG. 2, a male thread portion provided on the machining head 3 is indicated by reference numeral 11, and a differential transformer 10 is provided.
The female screw part formed in the male screw part and screwed to the male screw part 11 is indicated by reference numeral 12.

The differential transformer 10 has a probe 10a extending downward. The tracing stylus 10a is vertically movable within a predetermined range with respect to the main body 10b in which the female screw portion 12 is formed, and is constantly urged downward by a spring or the like. The lower end, that is, the tip, of the tracing stylus 10a is
The vertical position of the tracing stylus 10a is set to the neutral position when the tracing stylus 10a is located at a position corresponding to the focal position of the laser beam emitted from the camera. When the tracing stylus 10a shifts upward or downward from the neutral position, a signal corresponding to the shift amount from the neutral position is output from the differential transformer 10.

The base member 2 holds a pressing roller 21 as pressing means. This pressing roller 21
Is fixed via a support rod 22 to a piston rod 23a of, for example, an air cylinder 23 as a pressing source. The air cylinder 23 urges the pressing roller 21 downward with a predetermined constant force.

In FIG. 1, reference numeral 31 denotes a work to be laser-welded. In the embodiment, a flange portion 31A of an inner panel and a flange 31B of an outer panel are shown. These two flange portions 31A and 31
B is a portion to be welded, and is to be laser-welded in a state of being superposed on each other. Flange part 31
A and 31B extend in the left-right direction in FIG. 1, and the left-right direction is the welding direction for laser welding. In the later-described teaching and subsequent laser welding, the flange portions 31A and 31B are supported from below by a plurality of jigs 32 provided at intervals in the welding direction. The pressing roller 21 is disposed at a position slightly shifted in the welding direction with respect to the processing head 3, but is set so as not to be shifted in the width direction (the direction perpendicular to the plane of FIG. 1). ing.

In FIG. 1, U is a controller (control unit) as control means constituted by using a microcomputer. A signal indicating a robot position (a robot hand position corresponding to the position of the base member 2 and the position of the processing head 3) is input to the controller U. Further, a signal from the encoder 7 is provided to the controller U,
A signal from the differential transformer 10 is input. The controller U outputs a drive control signal to the motor 6.

Next, the teaching method and the subsequent laser welding method will be described with reference to FIG. First, at the time of teaching, the differential transformer 10 is fixed to the processing head 3. In this state, the robot, that is, the robot hand 1 is moved along the welding direction from the welding start position of the flange portions 31A and 31B to the welding end position. At this time, the pressing roller 21 is
1A and 31B are moved in the welding direction on the upper flange 31A while pressing the same downward. With the movement, the tip of the tracing stylus 10a is also moved in the welding direction while being in contact with the upper surface of the upper flange portion 31A.
At the welding start position, it is necessary to change the robot position from the state where the tracing stylus 10a is initially set to the neutral position corresponding to the laser beam focal position. This is preferable in order to prevent the occurrence.

At the time of the above movement, the output value from the differential transformer 10 according to the robot position is stored in the storage means provided in the controller U. That is, the robot position (the displacement position in the welding direction) and the flange portions 31A, 31
The correspondence relationship between B and the vertical displacement position (actually, the vertical displacement from the neutral position of the tracing stylus 10a corresponding to the focal position of the laser beam) is stored. When memorizing,
When the shift amount is smaller than a predetermined allowable value (for example, 1 mm), it is preferable to store such that there is no shift (the shift amount is zero) (the focal point of the laser beam is a predetermined length in the optical axis direction). And the allowable value is set in consideration of the predetermined length).

The teaching is completed by obtaining (storing) the correspondence between the vertical displacement positions of the flange portions 31A and 31B for all robot positions from the welding start position to the welding end position.

After the teaching is completed, laser welding is actually performed in a state where the differential transformer 10 is removed from the state shown in FIG. At this time, the control is performed so that the processing head 3 is at the vertical position corresponding to the robot position.
The drive of the motor 6 is controlled by the motor U. That is,
The vertical position of the processing head 3 is controlled so that the shift amount stored corresponding to the robot position is compensated and the focal point of the laser beam is located at the overlapping portion of the flange portions 31A and 31B. More specifically, when the stored shift amount is shifted upward from the reference position, for example, it means that the focus of the laser beam has shifted upward from the flange portions 31A and 31B as it is. The processing head 3 is displaced downward by an amount corresponding to the deviation amount (when the stored deviation amount is lower than the reference position, the processing head 3 is displaced upward). The control for displacing the processing head 3 by the stored shift amount is feedback-controlled using the output from the encoder 7.

Although the embodiment has been described above, the present invention is not limited to this and includes, for example, the following case. As a measuring means used at the time of teaching,
Not only the differential transformer 10 but also an appropriate type such as an optical type using laser light can be used. The measuring means is provided at a position where it does not interfere with the irradiation of the welding laser beam from the processing head 3, and the measuring means is kept attached to the processing head 3 not only during teaching but also during execution of laser welding. It can also be.

In the embodiment, the pressing roller 21 is provided on the front side in the welding direction with respect to the working head 3, but may be provided on the rear side in the welding direction, or may be provided on both front and rear sides in the welding direction. . Of course, the pressing means may be of a type that slides on the portion to be welded without using the roller 21 to be rolled. However, the use of the roller reduces the movement resistance to the portion to be welded. The above is preferable. Note that the present invention may not have the pressing means.

The portion to be welded, that is, the work to be laser-welded is not limited to a member for constituting an automobile body, but may be any appropriate member as long as it can be laser-welded.
The stored value stored corresponding to the robot position is not limited to the amount of deviation from the neutral position corresponding to the laser light focal position, but may be the processing head 3 from an arbitrarily set position (that is, the focal position of the laser light). (For example, a height position from the origin position indicating the robot position). The purpose of the present invention is not limited to what is explicitly specified, but also implicitly includes providing what is substantially preferred or expressed as an advantage.

[Brief description of the drawings]

FIG. 1 shows one embodiment of the present invention, and is a side view showing a state at the time of teaching.

FIG. 2 is a partial cross-sectional side view showing an example for detachably attaching a differential transformer to a processing head.

[Explanation of symbols]

 1: Robot hand 2: Base member 3: Processing head 6: Motor (driving means) 10: Differential transformer (measuring means) 10a: Measuring element 21: Pressing roller (pressing means) 31: Work 31A, 31B: Flange Part (welded part) U: Controller (control means) R: Laser beam

Claims (6)

[Claims] 1. A teaching method in a laser welding apparatus having a laser processing head at a tip end of a robot and performing welding of a workpiece by a laser beam emitted from the processing head, wherein the processing head is in an optical axis direction thereof. And a driving means for driving the processing head in the optical axis direction. The processing head is provided with a value relating to a distance between a focus position of laser light emitted from the processing head and a work. A measuring means for measuring is provided, a measurement is performed by the measuring means while displacing the processing head in a welding direction by a robot, a measurement result by the measuring means corresponding to the robot position is obtained, and the measurement result is stored. A teaching method for a laser welding apparatus, characterized in that: 2. The robot according to claim 1, wherein the measurement result obtained by said measuring means is a deviation amount from a predetermined reference value, and when the deviation amount exceeds a predetermined allowable value, the robot position is determined. A teaching method for a laser welding apparatus, wherein a corresponding shift amount is stored. 3. The robot according to claim 1, wherein a pressing means for pressing a portion to be welded on the workpiece is provided at a position shifted in the welding direction with respect to the processing head, at a distal end portion of the robot. A method for teaching a laser welding apparatus, wherein the measurement by a measuring unit is performed while the welding unit is being pressed by the pressing unit. 4. A laser welding method comprising providing a laser processing head at a tip of a robot and welding a workpiece by a laser beam emitted from the processing head, wherein the processing head is displaceable in an optical axis direction thereof. And a driving unit that drives the processing head in the optical axis direction is provided, and a measurement unit that measures a value related to a distance between a work and a focal position of laser light emitted from the processing head is provided. A storage unit is provided for performing measurement by the measurement unit while displacing the processing head in a welding direction by a robot, and storing a measurement result by the measurement unit corresponding to a robot position, and a storage stored in the storage unit. A laser welding method, wherein laser welding is performed while controlling the driving means according to a value. 5. A laser welding apparatus having a laser processing head at the tip of a robot and performing welding of a workpiece by a laser beam emitted from the processing head, wherein the processing head is displaceable in an optical axis direction thereof. And a driving unit that drives the processing head in the optical axis direction is provided, and a measurement unit that measures a value related to a distance between a work and a focal position of laser light emitted from the processing head is provided. A storage unit is provided for performing measurement by the measurement unit while displacing the processing head in a welding direction by a robot, and storing a measurement result by the measurement unit corresponding to a robot position, and a storage stored in the storage unit. A laser welding apparatus, further comprising control means for controlling the driving means according to a value. 6. The robot according to claim 5, further comprising: pressing means for pressing a portion to be welded on the workpiece at a position shifted in the welding direction with respect to the processing head, at a tip end of the robot. And welding with laser light,
The laser welding apparatus is performed while pressing the welded portion by the pressing means.