JP5061640B2 - Laser welding apparatus and laser welding method - Google Patents

Description

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

In recent years, laser welding has come to be used for welding using a robot. As such a welding technique, by attaching a laser irradiation device for irradiating a laser beam to the tip of a robot arm (manipulator) and moving the robot arm, further changing the direction of laser beam irradiation from the laser irradiation device, There is a technique for welding a predetermined welding point while moving a laser beam (see, for example, Patent Document 1). Such welding is called remote welding because the workpiece and the laser irradiation apparatus are further away from each other.
Japanese Patent Laid-Open No. 10-18471

  However, unique problems in such remote welding have become apparent. One of them is penetration marks and blow holes when forming weld beads by laser irradiation.

  In conventional remote welding, the laser beam output intensity is constant from the beginning to the end of the processing pattern for welding, so that the laser beam penetrates the workpiece to be welded, in order to make sure that the hot water is carried out. It was welded with. For this reason, on the back surface of the member to be welded (the side through which the laser penetrates), there is a problem that a penetration mark is generated, and in the worst case, the meat is lost and a blow hole is formed.

  Accordingly, an object of the present invention is to provide a laser welding apparatus and a laser welding method capable of preventing the occurrence of blowholes and minimizing the penetration marks generated on the back surface of the member to be welded.

In order to solve the above problems, the present invention provides a laser irradiation means having a reflecting mirror for changing the irradiation direction of laser light, a moving means for moving the laser irradiation means, and a movement taught in advance for the laser irradiation means. The moving means is controlled to move according to a path, and the laser light is emitted from the laser irradiation means, and the processing control means for controlling the movement of the reflecting mirror so as to draw a predetermined processing pattern. the heat input in the welding points were due to laser light have a, a laser light control means for changing in accordance with the irradiation position of the laser beam to draw the working pattern, the laser beam control means, the entering-heat, the At the beginning of drawing the pattern for processing, the laser beam is set to the first heat input amount penetrating the member to be welded, and then the laser beam is lowered below the first heat input amount The second heat input amount that does not penetrate through the second heat input amount, the second heat input amount, the first heat input amount is increased again, and then the second heat input amount is repeated. The laser welding apparatus is characterized in that when the irradiation position is close to a position at which the processing pattern starts to be drawn, the second heat input is set so that the laser beam does not penetrate the member to be welded .

Moreover, the present invention for solving the above-mentioned problems is a method for controlling a laser welding apparatus, comprising: laser irradiation means including a reflecting mirror that changes the irradiation direction of laser light; and moving means for moving the laser irradiation means. The moving means moves the laser irradiation means along a movement path taught in advance, and the laser light emitted from the laser irradiation means draws a predetermined processing pattern. The amount of heat input at the welding point is changed in accordance with the irradiation position of the laser beam that controls the movement of the reflecting mirror and draws the processing pattern. The intensity of the laser beam is the laser beam at the start of drawing the processing pattern. Is the first heat input amount that penetrates the welded member, and then the second heat input amount is lower than the first heat input amount so that the laser beam does not penetrate the welded member. After the amount of heat input is increased to the first heat input amount again, and then the second heat input amount is repeated again, and the irradiation position of the laser beam is the start of drawing the processing pattern. The laser welding method is characterized in that when the position is close to the position, the second heat input is such that the laser beam does not penetrate the member to be welded .

  According to the present invention configured as described above, at the start of the processing pattern, the laser beam is irradiated so that the laser beam has a first heat input amount that penetrates the member to be welded, and thereafter the laser beam is irradiated. Since the laser light is irradiated so that the second heat input is such that the light does not penetrate the welded member, the molten pool necessary for obtaining the bonding strength is formed by the first heat input, and thereafter Since a sufficient molten pool is formed to join the members to be welded even as the second amount of heat input that does not penetrate, sufficient heat is not applied, so that more heat than necessary is not applied. Generation of blow holes can be prevented. Moreover, since the penetration mark in the back surface (the side through which the laser beam penetrates) of the member to be welded can only be in the first part of the start of welding, the welding mark on the back surface can be reduced more than before.

  Hereinafter, embodiments to which the present invention is applied will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a schematic configuration diagram of a laser welding system to which the present invention is applied, FIG. 2 is an internal structure diagram of a laser irradiation apparatus in the laser welding system, and FIG. 3 is a laser oscillator in the laser welding system. FIG.

  The laser welding system shown in FIG. 1 directly touches the workpiece W by irradiating the workpiece W, which is a workpiece to be processed, with the laser beam 100 from the laser irradiation device 3 positioned on the workpiece W. Without welding, the workpiece W is welded.

  The illustrated laser welding system includes a robot 1 (moving means), a laser irradiation device 3 (laser irradiation means) that is attached to the tip of an arm 2 of the robot 1, and a laser oscillator that generates laser light. 5, a fiber optic cable 6 for guiding laser light from the laser oscillator 5 to the laser irradiation device 3, a robot control device 7 (processing control means and laser light control means) for controlling the operation of the robot 1 and the laser irradiation device 3, It comprises a teach box 8 for sending various instructions to the robot controller 7. In addition, this system can acquire teaching data and processing pattern data, which will be described later, from the CAD system 9. The CAD system 9 does not need to be always connected.

  The robot 1 is a general multi-axis robot, and the arm 2 is driven in accordance with route data given by the teaching work, and the laser irradiation device 3 can be moved to various three-dimensional positions and directions. A YAG laser is used as the laser oscillator 5, and the laser light generated by the laser oscillator 5 is guided to the laser irradiation device 3 by the optical fiber cable 6.

  The laser irradiation device 3 reflects the guided laser beam with a built-in reflecting mirror 11 (reflecting mirror), and scans the processing spot (hereinafter referred to as a welding point) of the workpiece W with a powerful laser beam 100. The scanned laser beam 100 is irradiated onto the welding point, and welding of the welding point (formation of a weld bead) is performed according to the shape scanned by the laser irradiation device 3.

  The robot control device 7 controls the operation of the robot 1 while recognizing the posture of the robot 1 and also controls the laser irradiation device 3 (control of the reflection mirror 11) in order to scan by changing the irradiation direction of the laser beam. Yes. The control of the reflecting mirror 11 is performed so as to draw an easily predetermined processing pattern to be described later. The robot controller 7 also controls ON / OFF of the laser output from the laser oscillator 5.

  The laser irradiation device 3 is configured to freely change the irradiation direction of the input laser light and visible laser light (visible light). That is, as shown in FIG. 2, the laser irradiation device 3 rotates the reflection mirror 11 (reflection mirror) for irradiating the laser beam 100 guided by the optical fiber cable 6 toward the welding point and the reflection mirror 11. Motors 16 and 17 to be moved and the lens group 12 are provided.

  The reflection mirror 11 is supported so as to be independently rotatable about the X axis and the Y axis perpendicular to the Z axis, with the vertical axis passing through the mirror surface as the Z axis. The motor 16 and the motor 17 change the direction of the reflection mirror 11 to a three-dimensional direction by combining the rotation positions of the respective motors. Therefore, the reflection mirror 11 is attached so as to be able to emit laser light incident from the optical fiber cable 6 in a three-dimensional direction. By rotating the reflecting mirror 11 in a three-dimensional direction, a scanning pattern (processing pattern) having a predetermined shape can be drawn at a welding point set on the workpiece W.

  Also, the amount of heat input can be adjusted by the moving speed (rotation speed) of the reflecting mirror 11. That is, if the moving speed of the laser beam that draws the processing pattern is decreased by moving the reflecting mirror 11, the amount of laser light incident per unit time at the welding point increases, and the amount of heat input at the welding point increases. On the other hand, if this is speeded up, the amount of laser light incident per unit time decreases, and the amount of heat input at the welding point decreases.

  The change of the laser beam intensity by changing the moving speed of the reflection mirror 11 is performed according to an instruction from the robot controller 7. This laser beam intensity change instruction is made in advance according to the position of the processing pattern (details will be described later).

  The lens group 12 includes a collimating lens 121 for collimating laser light emitted from the end of the optical fiber cable 6 and a condensing lens 122 for condensing the laser light 100 that has become parallel light on the workpiece W. Consists of Then, by changing the position of the condensing lens 122, the laser irradiation device 3 changes the position where the laser beam connects the store according to the distance from the welding point to the reflection mirror 11. It should be noted that such a change of the focal position (condenser lens position changing operation) is taught in advance together with the teaching of the movement path by the robot.

  As shown in FIG. 3, the laser oscillator 5 includes a visible laser beam oscillation source 502 such as a semiconductor laser in addition to a YAG laser oscillation source 501. The visible laser light oscillation source 502 is used, for example, for confirming a laser irradiation position. Whether to emit visible light or laser light for welding is switched by a switching mirror 503 inside the laser oscillator 5. That is, when the switching mirror 503 is at the solid line position, YAG laser light is output to the optical fiber cable 6, and when it is at the dotted line position, visible laser light is output to the optical fiber cable 6.

  The switching mirror 503 is switched by an instruction from the robot controller 7 or manually.

  Further, the intensity of the laser beam output from the laser oscillator 5 is changed by an instruction from the robot control device 7. This laser beam intensity change instruction is made in advance according to the position of the processing pattern (details will be described later).

  FIG. 4 is a block diagram of a control system of the laser welding system according to the present embodiment.

  The robot control apparatus 7 includes a teaching data storage unit 21 (teaching data storage unit), a robot control unit 22, a processing pattern storage unit 23 (processing pattern storage unit), a processing pattern generation unit 24, and a laser beam scanning control unit 25. (Processing control means and laser light control means).

  The teaching data storage unit 21 stores an operation path, an operation speed, and a welding point of the work W of the robot 1 previously taught by a teaching work by simulation using a CAD system. The welding point indicates the welding location of the workpiece W and is represented by three-dimensional coordinates. The teaching data may not be data taught by simulation, but may be teaching data using an actual machine.

  The robot control unit 22 controls the rotation amount of each axis motor of the robot 1 based on the teaching data, and the laser irradiation device 3 moves along a predetermined operation path so as to move to a predetermined position, for example, the workpiece W. Controls to stop sequentially at a predetermined position on the set welding point.

  The robot control unit 22 can also recognize the posture of the robot 1 based on the rotation amount (encoder value) of each axis motor of the robot 1. Therefore, the robot control unit 22 also functions as a posture recognition unit that recognizes the posture of the robot 1. Further, the robot control unit 22 has a function of determining whether or not the laser irradiation apparatus 3 is in a position where the laser beam can be irradiated to a welding point on which the workpiece W is based on the recognized posture of the robot. It also has.

  The processing pattern storage unit 23 stores a scanning pattern (processing pattern) at the time of processing of the laser beam 100 scanned by the laser irradiation device 3, and the laser beam intensity at the position of the processing pattern.

  The processing pattern stored in the processing pattern storage unit 23 may be an arbitrary shape having an arbitrary size. In the present embodiment, for example, an S-shaped machining pattern shown in FIG. 5 is stored. Such an S-shaped machining pattern has a vertical and horizontal size of the shape of the machining pattern, such that the vertical (welding length) is how many mm and the horizontal (welding width) is how many mm. Is defined as In this embodiment, the processing pattern is described as an S-shape, but it may be a rod shape as shown in FIG. 6 or a C-shape as shown in FIG. Since the processing pattern is created by CAD, the processing pattern storage unit 23 stores data from CAD.

  Here, a method for expressing the processing pattern will be described. The machining pattern is composed of a welding point center coordinate defined in the machining pattern and a plurality of point sequence coordinates defined by an offset amount from the welding point center coordinate. It is expressed with the coordinates of the same coordinate system.

  For example, when the processing pattern has an S shape as shown in FIG. 5, the weld length and weld width of the S shape are defined as shown in the figure. The S-shaped center of gravity (which is the center position of the processing pattern) is the welding point center coordinate (Wxcnt, Wycnt, Wzcnt), and the welding point center coordinate is the origin and the same coordinate system (Wx, Wy, Wz) is defined. The 80 point sequence coordinates (Wxcnt + Wx (0), Wycnt + Wy (0), Wzcnt + Wz (0)) constituting the S-shape are expressed as welding points (Wxcnt + Wx (79), Wycnt + Wy (79), Wzcnt + Wz (79)). It is defined as an offset amount (vector amount indicated by a dotted line in the figure) from the center coordinates. The amount of offset indicated by this vector indicates how far each point constituting the S-shape is away from the center coordinates of the welding point. The offset amount can be defined as a two-dimensional offset amount or can be defined as a three-dimensional offset amount.

  When the machining pattern has a bar shape as shown in FIG. 6, the bar center of gravity is the welding point center coordinate (Wxcnt, Wycnt, Wzcnt), and the welding point center coordinate is the origin and the same coordinates as the workpiece W. A system (Wx, Wy, Wz) is defined. The 30 point sequence coordinates (Wxcnt + Wx (0), Wycnt + Wy (0), Wzcnt + Wz (0)) constituting the rod shape are (Wxcnt + Wx (29), Wycnt + Wy (29), Wzcnt + Wz (29)) It is defined as an offset amount from the coordinates (vector amount indicated by a dotted line in the figure).

  Further, when the machining pattern has a C-shape as shown in FIG. 7, the center of gravity of the C-shape is the welding point center coordinate (Wxcnt, Wycnt, Wzcnt), and the welding point center coordinate is the origin, and the workpiece W The same coordinate system (Wx, Wy, Wz) is defined. Then, the 80 point sequence coordinates (Wxcnt + Wx (0), Wycnt + Wy (0), Wzcnt + Wz (0)) constituting the C-shape are (Wxcnt + Wx (79), Wycnt + Wy (79), Wzcnt + Wz (79)) It is defined as an offset amount (vector amount indicated by a dotted line in the figure) from the center coordinates.

  The machining pattern stored in the machining pattern storage unit 23 is also created by the CAD system 9 (see FIG. 1) in the same manner as the welding point. However, the welding point and the machining pattern are individually and independently created by the CAD system 9. Let me teach. That is, the welding point and the processing pattern can be handled as completely different data. For this reason, the teaching data storage unit 21 and the processing pattern storage unit 23 are provided separately.

  From the shape of the processing pattern stored in the processing pattern storage unit 23, the processing pattern generation unit 24 stores the shape as it is stored, or the instruction unit 26 that the teach box 8 has. A shape having a size instructed by is generated.

  The instruction unit 26 arbitrarily designates the size of the processing pattern drawn on the welding point of the workpiece W. For example, the instruction data storage unit 21 stores the vertical direction of the S shape that is the processing pattern. The instruction is given according to, for example, the welding strength required for the welding point so as to say three times the stored S shape and 1.5 times the lateral direction. Note that the size of the processing pattern may be embedded in advance in a program that is read when laser welding is performed, instead of an instruction from the instruction unit 26. Further, the instruction by the instruction unit 26 is stored once it is pointed at the time of motion teaching, and a pattern is drawn so as to surround the stored size during laser welding.

  The laser beam scanning control unit 25 is represented by coordinates in the same coordinate system as the workpiece W, and a plurality of point sequence coordinates defined by the welding point center coordinates of the machining pattern and the offset amount from the welding point center coordinates. Is converted into coordinates in the coordinate system of the robot 1. The laser beam scanning control unit 25 inputs the machining pattern having the size generated by the machining pattern generation unit 24, and also considers the posture of the robot 1 recognized by the robot control unit 22, and performs welding. Point sequence coordinates (about 80 points) of the processing pattern shape drawn on the points are calculated, and the reflection mirror 11 of the laser irradiation apparatus 3 is rotated based on the point sequence coordinates.

  Further, the laser beam scanning control unit 25 controls the amount of heat input to the welding point by the laser beam according to the irradiation position of the laser beam drawn on the welding point (position on the processing pattern).

  Next, the operation of the system configured as described above will be described.

  FIG. 8 is a drawing for explaining the control of the heat input according to the position of the processing pattern, (a) is a drawing schematically showing the cross section of the welding point (processing pattern), ) Is a graph showing the change in heat input according to the position of the processing pattern. In FIG. 8A, the cross-section of the linear pattern is shown, but this is merely a diagram for explaining the cross-section of the processing pattern, and the processing pattern is a curved line such as an S-shape or C-shape. Even in such a case, the same applies.

  In the present embodiment, as shown in the figure, the heat input amount is such that the laser beam penetrates through the two workpieces W1 and W2 that are the members to be welded at the start position (section k1) of the machining pattern. (The first heat input amount h1), and the subsequent position (section k2) is set to the heat input amount (second heat input amount h2) in which the laser beam does not penetrate the workpieces WI and W2. Here, the amount of heat input is the amount of heat per unit time generated by laser light irradiation.

  Such control of the heat input amount is first set to the first heat input amount h1 that penetrates the workpieces W1 and W2 at the position where the machining pattern starts to be drawn. At this stage, the molten pool 101 sufficient for the workpieces W1 and W2 to be completely fixed is formed at the laser beam irradiation point. With the formation of the molten pool 101 portion, the periphery of the molten pool 101 is heated including the direction in which the laser light is advanced along the processing pattern. This heating region is not so large, but is large enough to form a weld bead as a processing pattern.

  Thereafter, the amount of heat input is reduced to the second amount of heat input h2, and the laser light is subsequently advanced along the processing pattern. At this stage, as described above, the portion k2 for advancing the laser beam along the processing pattern is also heated to some extent. Therefore, even if the heat input is lowered to the extent that the two workpieces are not penetrated, the workpiece A sufficient weld bead is formed to melt to the position of the mating surfaces of W1 and W2 and to join them.

  As a result, sufficient bonding strength can be obtained, and penetration marks on the back surface (the side through which the laser beam penetrates) of the member to be welded can be reduced.

  Here, for reference of the present embodiment, a case will be described in which laser light is irradiated so as to obtain a heat input amount that penetrates the entire length of the processing pattern.

  FIG. 9A is a drawing schematically showing a cross section when laser welding is performed with the same amount of heat input that penetrates the member to be welded over the entire length of the processing pattern, and FIG. 9B is a diagram of the processing pattern. It is drawing which showed typically the cross section at the time of performing laser welding with the same heat input of the grade which does not penetrate through the full length.

  In the case of the one shown in FIG. 9 (a), since laser welding was performed with the same amount of heat input that penetrates the member to be welded over the entire length of the processing pattern, the laser beam having passed through the workpieces W1 and W2 causes a large back surface. Penetration marks remain. In addition, the welding point may be heated too much and the blow hole BH may be vacant.

  In the case of the one shown in FIG. 9 (b), since laser welding was performed with the same amount of heat input that does not penetrate the workpiece to be welded over the entire length of the processing pattern, although there is no penetration mark on the back surface, the amount of heat input is small from the beginning. There is a possibility that a poor weld may occur because a sufficient molten pool is not formed on the joint surface between the workpieces W1 and W2.

  As described above, when the heat input is constant over the entire length of the processing pattern, there may be various problems, but as described above, the heat input is changed in the middle of the processing pattern as in this embodiment. By changing it, sufficient bonding strength can be obtained, and the backside traces can be minimized.

  Next, control for changing the amount of heat input will be described.

  The degree of change when changing from the first heat input amount to the second heat input amount is preferably changed according to the thickness of the workpiece.

  For example, assuming that the laser beam is irradiated from the workpiece W1 side (the same applies hereinafter), if the thickness of the two workpieces W1 and W2 is smaller than W2 (W1 <W2), the first input is performed. When the heat amount is 100%, the second heat input amount may be 40 to 50%. If the first heat input is about to penetrate the workpieces W1 and W2 when the workpieces W1 and W2 are overlapped, the melting by laser irradiation is achieved if the second heat input is 40 to 50% of the first heat input. The depth of the pond is a position that is approximately half the total thickness of the workpieces W1 and W2, that is, a position that reliably passes through the workpiece W1 to reach the workpiece W2 and does not penetrate the workpiece W2. When the thickness of the workpiece is W1 <W2, the second heat input is such that the depth of the molten pool does not reach the workpiece W2 reliably through the workpiece W1 and does not penetrate the workpiece W2. Any value may be acceptable, and may be a value exceeding 50% of the first heat input (eg 60%, 70%, 80%, etc.). It can be executed by doubling the rotation speed of the reflection mirror 11 or halving the laser intensity with respect to the heat input, and is most easily controlled.

  Further, for example, when the workpiece W1 is thicker (W1> W2), in this case, the depth of the molten pool surely passes through the workpiece W1 and reaches the workpiece W2, so that the thickness of W1 / (W1 The upper limit is about (thickness + W2), and the lower limit is preferably about 10%. As a specific example, when the workpiece W1 = 0.8 mm and W2 = 0.6 mm, when the first heat input is 100%, the second heat input is 0.8 / (0.8 + 0). .6) = approx. 57%, 47-57% may be set. Thereby, the depth of the molten pool penetrates the workpieces W1 and W2 in the first heat input amount, and does not pass through W1 to some extent and does not penetrate W2 in the second heat input amount. Here, the lower limit value of the second heat input amount is made lower than the value corresponding to the thickness of the workpiece W1 with respect to the total thickness of the two workpieces. Therefore, if this is simply reduced in accordance with the thickness of the workpiece W1, the second heat input amount is too high, and the second heat input amount is increased. This is because there is a possibility that two workpieces may penetrate even if the amount of heat input is. Therefore, a preferable value of the second heat input amount is preferably lower than a value corresponding to the thickness of the workpiece W1 with respect to the total thickness of the two workpieces.

  Since these are merely examples, the first heat input amount and the second heat input amount depend on the material and thickness of the member to be welded, the first heat input amount penetrates, and the second heat input amount is All the members to be welded may not be penetrated, but may be set so as to penetrate only the workpiece on the laser beam irradiation side.

  The amount of heat input can be controlled by changing the speed at which the reflecting mirror 11 is rotated, changing the intensity of the laser beam output from the laser oscillator 5, and a combination of both.

  For example, when the first heat input amount is 100% and the second heat input amount is 50%, the rotational speed of the reflection mirror 11 when the laser beam is irradiated so that the first heat input amount is obtained. On the other hand, what is necessary is just to double the rotational speed of the reflective mirror 11 when irradiating a laser beam so that it may become 2nd heat input. Similarly, for example, when the first heat input amount is 100% and the second heat input amount is 25%, the second heat input amount with respect to the rotation speed of the reflecting mirror 11 at the first heat input amount. The rotational speed of the reflecting mirror 11 at this time may be about 4 times.

  Further, when the first heat input amount is 100% and the second heat input amount is 50%, the intensity of the laser output from the laser oscillator 5 when the laser light is irradiated so as to be the first heat input amount. On the other hand, in order to achieve the second heat input amount, the intensity of the laser output from the laser oscillator 5 may be halved. Similarly, for example, when the first heat input is 100% and the second heat input is 25%, the laser at the second heat input with respect to the laser output intensity at the first heat input. The output intensity may be reduced to about one quarter.

  Furthermore, in the case of combining these, when the first heat input is 100% and the second heat input is 50%, the rotational speed of the reflection mirror 11 at the first heat input is The rotation speed of the reflecting mirror 11 at the second heat input is increased by 25%, and at the same time, the laser output intensity at the second heat input is set to the laser output intensity at the first heat input. It may be reduced to about 75%. In particular, such a combination can be used to perform laser irradiation step by step with a laser transmitter, for example, when output adjustment with the laser transmitter can only be performed stepwise (for example, output 100%, 75%, 50%, 25%). It is suitable for adjusting the amount of heat input delicately by reducing the strength and adjusting the speed of the reflecting mirror 11.

  In this way, various heat input amounts can be controlled by various combinations of the rotation speed of the reflection mirror 11 and the laser output intensity output from the laser oscillator 5.

  Next, the position at which the heat input is changed with respect to the length direction of the processing pattern will be described.

  The position where the heat input is changed is basically set so that a sufficient welding strength can be obtained. Next, the penetration trace on the back surface (the side through which the laser beam penetrates) can be reduced as much as possible. Set as follows.

  For this reason, the position where the heat input is changed varies depending on the material and thickness of the member to be welded, the length of the welding pattern for processing, and the like. Therefore, in actuality, it must be obtained by experiment. For example, when the member to be welded is a steel plate, the range of the first heat input is set to 1/10 of the entire length of the processing pattern from the irradiation start point. It should be about 1/3.

  Also, when the processing pattern is long, after the second heat input amount, the first heat input amount is set again in the middle, the laser beam is penetrated again in the middle, and then the second heat input amount is set again. A sufficient welding strength may be obtained by repeatedly performing the control.

  10 and 11 are diagrams showing examples of changes in heat input with respect to the processing pattern.

  For example, in the case of the C-shaped machining pattern P shown in FIG. 10A, as shown in FIG. 10, the first heat input amount h1 is set to about 1/10 (section k1) from the irradiation start point, and thereafter Is the second heat input amount h2 in all positions (section k2).

  Further, for example, in the case of the S-shaped processing pattern P shown in FIG. 11A, the processing pattern is long, so that it is about one-tenth from the irradiation start point (section) as shown in FIG. As the first heat input amount h1 until k1), the subsequent position (section k2) is set as the second heat input amount h2, but it is set again as the first heat input amount (section k3) slightly before the intermediate position Pm. However, it should be noted here that if the position of the first heat input again is close to the position of the first heat input h1 at the welding start point, the amount of heat input becomes too large, so the processing pattern Depending on the shape, it is necessary to adjust the position of the first heat input again. In the case of the S-shape shown in the figure, since the intermediate position Pm is close to the laser irradiation start point, the first heat input amount h1 is set again a little before the intermediate position Pm that is slightly away from the intermediate position Pm. The second heat input amount h2 of k4 is set. Thereafter, laser irradiation is continued with the second heat input h2 until the end.

  For example, the control of the amount of heat input teaches in advance the rotational speed and / or laser output intensity of the reflecting mirror 11 for each position (point) of the point sequence coordinates when drawing the processing pattern. At the time of laser welding, control is performed so as to achieve the rotation speed and / or laser output intensity of the taught reflection mirror 11.

  Next, an operation processing procedure of the robot control device at the time of laser welding in the present embodiment will be described. FIG. 12 is a flowchart showing an operation processing procedure of the robot control apparatus.

  The basic operation during laser welding is when the robot is stopped at the taught position, laser welding is performed on one welding point that can be irradiated by the laser irradiation device 3 at that location, and the next welding point is laser-welded. Further, the operation of moving the robot to the next position and performing laser welding is repeated, and laser welding is sequentially performed point by point to complete laser welding for all the welding points.

  The robot controller 22 first reads teaching data for laser welding (S1). The teaching data describes, for example, the robot stop position, operation speed, welding point center coordinates, machining pattern, reflection mirror rotation speed, welding width, welding length, laser output intensity, and other operation commands necessary for control. ing. The robot operates accordingly.

  Next, the robot control unit 22 instructs to read the processing pattern data stored in the processing pattern storage unit 23 (S2).

  The robot control unit 22 operates the robot 1 according to the teaching data, moves the laser irradiation device 3 at the operation speed described in the teaching data, and positions the robot irradiation device 3 at the robot stop position. At the same time, the reflecting mirror 11 of the laser irradiation device 3 is positioned toward the welding point of the workpiece W (S3: robot operation, positioning). Specifically, the direction of the reflection mirror 11 is adjusted so that the laser beam is irradiated to the center coordinates of the welding point. From this position, the laser irradiation device 3 can irradiate a specific welding point with laser light.

  Next, the robot control unit 22 causes the machining pattern generation unit 24 to calculate the coordinate points necessary for drawing the machining pattern at the welding point of the workpiece W according to the read machining pattern (S4). In response to this instruction, the processing pattern generation unit 24 acquires the welding point center coordinates, the welding width, and the welding length, which are the basic shapes of the read processing pattern, described in the coordinate system of the workpiece W, and processes the pattern. The coordinates of each of the 80 basic points are calculated (S5).

  Subsequently, the processing pattern generation unit 24 calculates the calculated 80 basic point coordinates in the vertical direction (welding length direction) based on the “welding width” and “welding length” described in the read teaching data. Further, a bias process for generating a coordinate point of a machining pattern having a size that can be actually drawn is performed by shifting in the lateral (weld width) direction. Then, the robot control unit 22 instructs the laser beam scanning control unit 25 to convert the coordinates of the 80 points of the generated machining pattern from the workpiece coordinate system to the robot coordinate system (S6). .

  Next, the robot control unit 22 inputs the currently recognized posture of the robot 1, and a machining pattern having a required size is formed on the welding point of the workpiece W targeted by the current posture of the robot 1. The method of rotating the reflecting mirror 11 for drawing (the angle of the reflecting mirror 11 at each time point reaching each point (80 points) of the machining pattern from the start to the end of rotation) is calculated (S7). At this time, when the amount of heat input is controlled by the rotation speed of the reflection mirror, the reflection mirror 11 at each time at which the first heat input amount portion and the second heat input amount portion reach the respective positions. Find the angle. On the other hand, the laser output intensity control by the laser transmitter specifies the time to change the heat input from each time of the reflection mirror rotation position calculated here, and inputs an instruction to change the laser output at that time. Keep it.

  When the above calculation is completed, the robot control controller 22 instructs the laser oscillator 5 to output a laser beam (YAG laser beam) according to the teaching data. When the laser oscillator 5 is turned on, the laser beam is emitted toward the reflection mirror 11, and the reflection mirror 11 is instructed to rotate in the calculated rotation manner to the laser beam scanning control unit 25 ( S8).

  Thereafter, the laser beam scanning control unit 25 continues to rotate the reflection mirror 11 until the rotation of the reflection mirror 11 is completed (irradiation of the processing pattern is completed). An end signal is output to the unit 22. Receiving this, the robot control control unit 22 cancels the output command of the YAG laser from the laser oscillator 5 and stops the output of the laser beam (S9: laser irradiation end process). This completes the laser welding at one welding point position.

  By the above processing, irradiation of the processing pattern to one welding point is completed. When welding a plurality of welding points, the above processing is sequentially executed for the number of designated welding points.

  As a result, a weld bead with few penetration marks due to laser beam penetration is formed at a plurality of welding point positions on the workpiece W, each with a predetermined processing pattern.

  Next, the result of actual welding will be described.

  Based on this embodiment, the welding sample (first sample) subjected to laser welding and the welding sample (first sample) subjected to electric spot welding were respectively determined in the same manner.

  In both the first and second samples, the thickness of W1 is 0.8 mm, and the thickness of W2 is 0.65 mm. For the first sample, W1 is the workpiece on the laser irradiation side, and the processing pattern was a C-shaped pattern with a diameter of about 10 mm. The first heat input was about 1/5 of this pattern. The speed of the reflection mirror was adjusted so that the second heat input amount was about 70 to 80% with respect to the first heat input amount.

  On the other hand, the electric spot welding of the second sample is spot welding with a diameter of about 10 mm.

  As a result of the chisel determination, the workpiece base material itself was broken in the Dojiro sample. That is, there is no peeling at the welded portion, and sufficient bonding strength is obtained.

  In the first sample, although there were some through marks on the back side (the side through which the laser beam penetrates), there were no blowholes and there was little surface roughness. In addition, compared to the case where laser welding was performed with the same heat input so as to penetrate the entire length of the processing pattern separately performed, the size of the penetrating marks was very small.

  Although the embodiment of the present invention has been described above, the present invention is not limited to such an embodiment. For example, in the above-described embodiment, the robot 1 moves the laser irradiation device 3 to the vicinity of the welding shop, where the laser irradiation device 3 is stopped, and then the reflection mirror 11 is rotated to draw a processing pattern. Although the laser beam was irradiated, instead of this, the laser beam is drawn so as to draw a processing pattern by rotating the reflection mirror 11 in consideration of the moving speed in a state where the laser irradiation device 3 is always moved. May be irradiated. By doing in this way, when there are a plurality of welding points, the entire welding time can be shortened as long as the laser irradiation device 3 is not stopped.

  In addition, it goes without saying that the present invention can be variously modified.

  The present invention is suitable for laser welding.

1 is a schematic configuration diagram of a laser welding system to which the present invention is applied. It is an internal structure figure of the laser irradiation apparatus described in FIG. It is an internal structure figure of the laser oscillator described in FIG. It is a block diagram which shows the control system of the laser welding system which concerns on embodiment. It is a figure which shows an example of the shape of the pattern for a process used by embodiment. It is a figure which shows an example of the other shape of the pattern for a process used by embodiment. It is a figure which shows an example of the other shape of the pattern for a process used by embodiment. It is drawing for demonstrating control of the heat input according to the position of the pattern for a process. It is drawing which showed typically the cross section at the time of performing laser welding with the same heat input over the full length of the pattern for a process. It is drawing which shows the example of a change of the heat input with respect to the pattern for a process which concerns on embodiment. It is drawing which shows the example of a change of the heat input with respect to the other pattern for a process which concerns on embodiment. It is a flowchart which shows the welding procedure which concerns on embodiment.

Explanation of symbols

1 ... Robot,
2 ... arm,
3 ... Laser irradiation device,
5 ... Laser oscillator,
6 ... Optical fiber cable,
7 ... Robot controller,
8 ... Teach box,
9 ... CAD system,
11 ... reflecting mirror,
12 ... lens group,
21 ... Teaching data storage unit,
22 ... Robot controller,
23. In-area welding data storage unit,
23 ... Pattern storage unit for processing,
24 ... pattern generator for processing,
25. Laser beam scanning control unit,
26 ... instruction part,
100: Laser light,
121 ... collimating lens,
122 ... Condensing lens.

Claims (8)

Laser irradiation means comprising a reflecting mirror for changing the irradiation direction of the laser light;
Moving means for moving the laser irradiation means;
A processing control for controlling the movement means to move the laser irradiation means according to a movement path taught in advance and for controlling the movement of the reflecting mirror so that the laser beam draws a predetermined processing pattern. Means,
Laser light control means for changing the amount of heat input at the welding point by the laser light emitted from the laser irradiation means according to the irradiation position of the laser light that draws the processing pattern;
I have a,
The laser light control means sets the heat input amount to a first heat input amount through which the laser light penetrates the member to be welded at the start of drawing the processing pattern, and then the laser light is welded lower than the first heat input amount. The second heat input amount not penetrating the member, the second heat input amount, the first heat input amount is increased again, and then the second heat input amount is repeated, and then the laser light is repeated. The laser welding apparatus is characterized in that when the irradiation position is close to the position at which the processing pattern starts to be drawn, the second heat input is such that the laser beam does not penetrate the member to be welded . 2. The laser welding apparatus according to claim 1, wherein the laser light control unit changes the amount of heat input by changing an output of a laser oscillator that generates the laser light . 2. The laser welding apparatus according to claim 1 , wherein the laser light control unit changes the amount of heat input by changing a speed at which the laser light draws the processing pattern . The laser light control means changes the heat input amount by changing an output of a laser oscillator for generating the laser light and changing a speed at which the laser light draws the processing pattern. laser welding apparatus according to 1. Laser irradiation means comprising a reflecting mirror for changing the irradiation direction of the laser light;
A moving means for moving the laser irradiation means, and a control method for a laser welding apparatus comprising:
The moving means moves the laser irradiation means along a movement path taught in advance, and the reflecting mirror moves so that the laser light emitted from the laser irradiation means draws a predetermined processing pattern. And changing the amount of heat input at the welding point according to the irradiation position of the laser beam that draws the processing pattern,
The intensity of the laser beam is set to a first heat input amount at which the laser beam penetrates the member to be welded at the beginning of drawing the processing pattern, and then lower than the first heat input amount so that the laser beam does not penetrate the member to be welded. The heat input amount is set to the second heat input amount, and then the first heat input amount is increased again, and then the second heat input amount is repeated. The laser welding method is characterized in that the second heat input is set so that the laser beam does not penetrate the member to be welded when the position is close to the position at which the processing pattern starts to be drawn. The laser welding method according to claim 5, wherein the heat input amount is changed by changing an output of a laser oscillator that generates the laser light. The laser welding method according to claim 5, wherein the heat input amount is changed by changing a speed at which the laser beam draws the processing pattern. 6. The laser welding according to claim 5, wherein the amount of heat input is changed by changing an output of a laser oscillator that generates the laser light and changing a speed at which the laser light draws the processing pattern. Method.

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