JP5169460B2 - LASER WELDING METHOD, WELD FORMED BY THIS WELDING METHOD, AND LASER WELDING SYSTEM - Google Patents

Description

  The present invention relates to a laser welding method, a weld formed by the welding method, and a laser welding system.

  In recent years, laser welding has come to be used for welding using a robot. In such laser welding technology, a laser irradiation device for irradiating a laser is attached to the tip of a robot arm (manipulator), the laser irradiation device is moved to a welding position by the robot arm, and laser is irradiated from there to perform welding. I do.

  In this laser welding technique, an attempt has been made to shorten the process time (tact time) when welding a plurality of welds as much as possible. For example, when moving the laser irradiation device attached to the tip of the robot arm (robot hand), the time for the laser irradiation device to reach the welding position is predicted, and the laser transmitter is activated based on the prediction ( (Patent Document 1).

  In this technology, a delay in signal transmission due to a robot, laser irradiation device, laser transmitter, etc. being connected via an I / O interface is activated in advance by predicting the arrival time of the laser irradiation device (or It is intended to compensate by instructing (stop).

  This technique is based on the premise that welding is performed by irradiating a laser while constantly moving the robot hand.

On the other hand, among laser welding techniques, there is a technique in which a robot arm is stopped during laser welding, that is, a laser irradiation apparatus is stopped within a weldable range (Patent Document 2).
Japanese Patent Laid-Open No. 2007-237202 Paragraph 0010 of JP-A-2005-177862

  Therefore, it is conceivable to reduce the process time by applying the technique described in Patent Document 1 to the technique of performing laser welding by stopping the robot arm.

  However, when stopping the laser irradiation device, even if the time to reach this stop position is predicted and the laser transmitter is activated in advance, the laser irradiation should be performed immediately after the laser irradiation device stops at the welding position. The process time is not changed, and the process time is hardly reduced.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a laser welding method capable of reducing the process time in a technique for performing laser welding by stopping the movement of the laser irradiation apparatus, a welded article manufactured by this method, and a laser welding system. It is to be.

In order to solve the above problems, the present invention moves the laser irradiation means to the welding point of the member to be welded and, after the movement , moves the laser irradiation means from the laser irradiation means to the welding point in a deceleration region for stopping the laser irradiation means. The laser welding method is characterized in that the laser irradiation is started, the laser irradiation unit is stopped while continuing the laser irradiation, and the laser irradiation is further continued after the laser irradiation unit is stopped. Further, the present invention for solving the above-mentioned problems is that the laser irradiation means is moved to the welding point of the member to be welded, laser irradiation is started from the laser irradiation means toward the welding point in the middle of the movement, and the laser The laser irradiation unit is stopped while continuing the irradiation, and after the laser irradiation unit is stopped, further laser irradiation is continued, and further, acceleration is started to move the laser irradiation unit again from the stop position. The laser welding method is characterized in that the laser irradiation is continued until the laser irradiation means reaches a predetermined position.

  Further, the present invention for solving the above problems is a welded article welded by the above laser welding method, and is formed by laser irradiation from the laser irradiation means toward the welding point from the middle of movement, A welded product comprising a weld bead including a portion formed by drawing a predetermined processing pattern after stopping the laser irradiation means following the introduction portion weld bead.

Furthermore, the present invention for solving the above-described problems is directed to a moving means, a laser irradiation means attached to the moving means, and a movement of the laser irradiation means by the moving means to weld a welding point of a member to be welded. Starting laser irradiation from the laser irradiation means toward the welding point in the middle of the movement, stopping the laser irradiation means while continuing the laser irradiation, and after stopping the laser irradiation means, to continue the laser irradiation, and control means for controlling the moving means and the laser irradiating means, have a, said control means further acceleration to move the laser irradiation unit again from the position of the stop from the starting point in time, the laser welding the laser irradiation means to a predetermined position, characterized in that to continue the laser irradiation until reaching Shi Is Temu.

  According to this invention comprised as mentioned above, the process time (tact time) accompanying welding operation can be shortened. In addition, the length of the weld bead is longer than that of the conventional one due to the presence of the weld bead in the introduction portion formed in the deceleration region, and the weld quality is improved. Moreover, even if the weld bead is lengthened, the process time does not increase at all, and on the contrary, it can be shortened as compared with the prior art.

  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 illustrates control of the laser welding system. It is a block diagram for doing.

  The laser welding system shown in FIG. 1 does not touch the workpiece W directly by irradiating the workpiece W, which is an object to be welded as a workpiece, with the laser 100 from the laser irradiation device 3 stopped on the workpiece W. 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 irradiates a laser 100, and a laser oscillator 5 that generates a laser. The optical fiber cable 6 guides the laser from the laser oscillator 5 to the laser irradiation device 3, and the robot 1 and the robot control device 7 (control means) for controlling the operation of the laser irradiation device 3. In addition, as will be described later, this system is connected to a robot and a teaching box 8 for teaching the robot of the laser irradiation position, and a CAD system 9 for sending the processing pattern data of the welding points to the robot controller 7. 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 generated by the laser oscillator 5 is guided to the laser irradiation device 3 by an optical fiber cable 6.

  The robot control device 7 controls the operation of the robot 1 while recognizing the posture and the current position of the robot 1, and controls the laser irradiation device 3 (the reflection mirror 11 (FIG. 2)) in order to change and scan the laser irradiation direction. Control). The control of the reflecting mirror 11 is performed so as to draw a predetermined processing pattern as will 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 and visible laser (visible light). That is, as shown in FIG. 2, the laser irradiation device 3 moves the reflection mirror 11 (reflection mirror) for irradiating the laser 100 guided by the optical fiber cable 6 toward the welding point, and the reflection mirror 11. Motors 16 and 17 and lens group 12 are included. Thereby, the laser irradiation device 3 reflects the guided laser beam by the reflection mirror 11 (reflection mirror) and irradiates the welding point of the workpiece W. At the welding point, the irradiated laser forms a weld bead that becomes a predetermined processing pattern.

  The reflection mirror 11 is supported so that the X axis and the Y axis can be rotated independently of each other. The motor 16 and the motor 17 change the direction of the reflection mirror 11 in a three-dimensional direction by combining the rotational positions of the respective motors. Therefore, the reflection mirror 11 is attached so that the laser incident from the optical fiber cable 6 can be emitted in a three-dimensional direction. By moving the reflecting mirror 11 in a three-dimensional direction, it is possible to weld a plurality of welding points set on the workpiece W from one stop position of the laser irradiation device 3.

  The amount of heat input can also be adjusted by the moving speed (moving speed) of the reflecting mirror 11. That is, if the moving speed of the laser that draws the processing pattern is slowed by moving the reflecting mirror 11, the amount of laser 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 incident per unit time decreases, and the amount of heat input at the welding point decreases.

  The lens group 12 includes a collimating lens 121 for making the laser emitted from the end of the optical fiber cable 6 parallel light and a condensing lens 122 for condensing the laser 100 that has become parallel light on the workpiece W. Is done. And the laser irradiation apparatus 3 changes the position which a laser connects a shop according to the distance from a welding point to the reflective mirror 11 by changing the position of the condensing lens 122. FIG. 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.

  FIG. 3 is a block diagram of a control system of the laser welding system according to the present embodiment.

  The robot control device 7 includes a teaching data storage unit 21, a robot control unit 22, a processing pattern storage unit 23, a processing pattern generation unit 24, and a laser scanning control unit 25.

  The teaching data storage unit 21 stores an operation path, an operation speed, and a welding point of the workpiece W that are previously taught. The teaching data such as the operation path, the operation speed, and the welding point of the workpiece W are the data taught by the teaching work by simulation using the CAD system or the teaching data created from the teach box 8 using the actual machine. is there. The welding point indicates the welding location of the workpiece W and is represented by three-dimensional coordinates.

  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 and current position of the robot 1 based on the rotation amount (encoder value) of each axis motor of the robot 1.

  Then, the robot control unit 22 determines whether or not the laser irradiation device 3 is in a position where the laser can be irradiated to the welding point of the workpiece W based on the recognized posture and position of the robot, and the laser Instruct the start and stop of irradiation. That is, in this embodiment, the robot control unit 22 starts laser irradiation from the stage of movement immediately before the laser irradiation device 3 stops at the stop position, and continues welding with the processing pattern after stop. Then, control is performed so that the operation of the robot is started before welding is completed (details will be described later).

  The processing pattern storage unit 23 stores a scanning pattern (processing pattern) during processing of the laser 100 scanned by the laser irradiation device 3 and the laser 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. FIG. 4 is a diagram showing an example of this processing pattern.

  The processing pattern has, for example, an S shape shown in FIG. 4A, a C shape shown in FIG. 4B, an I shape (bar shape) shown in FIG. Of course, various other patterns can be set. The processing pattern is created by CAD, and data from CAD is stored in the processing pattern storage unit 23.

  The processing pattern stored here is a pattern of a weld bead formed at a welding point. In this embodiment, laser irradiation is started before the laser irradiation device completely stops. It becomes a bead. However, the processing pattern stored here does not include that portion (details will be described later).

  The processing pattern generation unit 24 enlarges (or reduces) the shape of the processing pattern stored in the processing pattern storage unit 23 to the shape of the size as it is stored or a predetermined magnification. Generate a shape of the specified size. This magnification is stored in the processing pattern storage unit 23, and the instruction is embedded in the teaching data. It is also possible to change the instruction later from the teaching box 8. For example, the size of the processing pattern drawn on the welding point of the workpiece W is arbitrarily specified from the instruction unit 26 of the teaching box 8. Specifically, for example, the vertical direction of the S shape which is the processing pattern is three times the S shape stored in the teaching data storage unit 21 and the horizontal direction is 1.5 times as follows. It is possible to instruct according to, for example, the welding strength required for the welding point. Such a change instruction is also embedded in the teaching data.

  The laser scanning control unit 25 inputs the processing pattern having the size generated by the processing pattern generation unit 24, and also considers the posture of the robot 1 recognized by the robot control unit 22, and determines the position on the welding point. The point sequence coordinates (about 80 points) of the processing pattern shape to be drawn are calculated, and the reflection mirror 11 of the laser irradiation apparatus 3 is moved based on the point sequence coordinates.

  The laser scanning control unit 25 converts the coordinates of the machining pattern indicated by the plurality of point sequence coordinates from the center coordinates of the machining pattern into coordinates of the robot 1.

  FIG. 5 is an explanatory diagram for explaining the conversion of the machining pattern into the coordinate system of the robot 1.

  When the processing pattern has an S shape as shown in FIG. 5, for example, the weld length and weld width of the S shape are defined as shown in the figure. Here, the center of gravity of the S-shape (which is the center position of the processing pattern) is the welding point center coordinates (Wxcnt, Wycnt, Wzcnt). Therefore, the welding point center coordinates are the coordinates of the welding points stored as teaching data. Here, the coordinate system of the robot is defined as (Wx, Wy, Wz).

  On the other hand, about 80 point sequence coordinates constituting the S-shape are expressed by (Wx (79)) from about 80 point sequence coordinates (Wx (0), Wy (0), Wz (0)) centering on the welding point. , Wy (79), Wz (79)) are generated by the processing pattern generator 24.

  Therefore, the laser scanning control unit 25 converts the point sequence coordinates into the robot coordinate system.

  As a result of conversion, about 80 point sequence coordinates constituting the S-shape are changed from (Wxcnt + Wx (0), Wycnt + Wy (0), Wzcnt + Wz (0)) to (Wxcnt + Wx (79), Wycnt + Wy (79), Wzcnt + Wz (79)). It becomes.

  The laser scanning control unit 25 moves the reflection mirror 11 of the laser irradiation device 3 so that the laser is irradiated to these coordinates.

  The coordinates of the processing pattern may be specified as an offset amount (vector amount indicated by a dotted line) in addition to the conversion to the robot coordinate system. 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.

  This method is the same even if the shape of the processing pattern changes. FIG. 6 shows the case of a C-shaped pattern.

  Also in this case, as in the case of the S-shape, the center of gravity of the C-shape (which is the center position of the processing pattern) is set as the welding point center coordinates (Wxcnt, Wycnt, Wzcnt). From about 80 point sequence coordinates (Wx (0), Wy (0), Wz (0)) constituting the C-shape to (Wx (79), Wy (79), Wz (79)) The values converted into the coordinate system of the robot of the point sequence coordinates are (Wxcnt + Wx (0), Wycnt + Wy (0), Wzcnt + Wz (0)) to (Wxcnt + Wx (79), Wycnt + Wy (79), Wzcnt + Wz (79)).

  In this case as well, it can be defined as a two-dimensional or three-dimensional offset amount based on the illustrated vector.

  In addition, the processing pattern may be stored in the teaching data storage unit 21 as operation teaching data of the reflecting mirror 11 so that the processing pattern can be drawn with a predetermined pattern and size.

  The operation of the laser welding system configured as described above in this embodiment will be described.

  FIG. 7A is a time chart for explaining the welding operation in the present embodiment. Here, from entering one welding point to stopping welding and moving to the next welding point after welding is shown.

  In the figure, the horizontal axis is time.

  From the top, the head position item indicates the moving distance of the laser irradiation device 3 attached to the robot arm 2. The current position of the laser irradiation device 3 is referred to as a head position, and the data is referred to as position data. The position data is calculated from data from encoders attached to the motors of each part of the robot 1.

  The item of robot speed indicates the moving speed of the laser irradiation device 3.

  In addition, since the figure is only for explaining the timing of the operation, no unit is given for time, distance, or speed.

  First, the robot 1 is moving toward a welding point in a constant speed operation. When it is determined from the position data that the head position has reached A1, in order to stop the movement of the laser irradiation device 3, a robot stop command is output and a deceleration command for starting deceleration is issued. Normally, the motor rotation speed of the robot 1 is gradually decreased by the deceleration command and finally stopped completely.

  At this time, in this embodiment, the mirror operation and the laser irradiation are started when it is detected that the laser irradiation device 3 has come to the position A2 before the robot 1 completely stops. That is, laser irradiation is started toward the welding point before the laser irradiation device completely stops. Thereafter, since the laser irradiation device 3 reaches A3 and stops completely, the operation of the reflection mirror 11 is continued to form a weld bead having a working pattern.

  Thereafter, when the position of the reflection mirror 11 reaches the position A4 immediately before the processing pattern ends, the operation of the robot 1 is started (acceleration command). That is, the movement of the laser irradiation device 3 is started before the laser irradiation is completely completed.

  Thereafter, when the laser irradiation device 3 reaches the position A5, the mirror operation and the laser irradiation are stopped. After that, after the laser irradiation device 3 accelerates until it reaches the position A6, the acceleration command is stopped, and control is performed so that the speed becomes a constant speed (constant speed command), and the process proceeds to the next welding point. .

  FIG. 8 is an explanatory view illustrating an example of a weld bead performed by such a welding operation.

  FIG. 8A shows the case of an S-shaped pattern, FIG. 8B shows the case of a C-shaped pattern, and FIG. 8C shows the case of an I-shaped pattern.

  As shown in the drawing, an introduction portion A, an escape portion B, and a pattern portion C are formed in each pattern of the weld beads 50.

  The introduction part A is a weld bead formed by starting laser irradiation in a part of the deceleration region in which the laser irradiation device 3 is moving. That is, it is a weld bead made by laser irradiation in the section A2 to A3 in FIG.

  The escape portion B is a weld bead that is formed by starting the acceleration of the laser irradiation device 3 while continuing the laser irradiation. That is, it is a weld bead made by laser irradiation in the section A4 to A5 in FIG.

  The pattern portion C is a weld bead made of a processing pattern that is formed only by movement (rotation) of the reflection mirror 11 while the laser irradiation device 3 is completely stopped. That is, it is a weld bead made by laser irradiation in the section of A3 to A4 in FIG.

  Here, the section of the introduction part A is particularly important. The presence of the section of the introduction portion A is that a sufficient amount of heat input necessary for forming a weld bead in the pattern portion C by the subsequent processing pattern can be sufficiently provided to form a good keyhole. In forming the weld bead, the member to be welded melts at the start of laser irradiation to form a keyhole, and a weld bead is formed by continuing this. For this reason, it is necessary to apply a sufficient amount of heat to melt the member to be welded first to form a keyhole. By having this introduction part A, the amount of heat necessary for keyhole formation can be given to the welded member by applying a laser while moving the laser irradiation point to this part. Therefore, even if the welded member does not immediately melt by laser irradiation at the first position AS of the introduction part A, sufficient heat is generated because the welded member melts to the position AE where the introduction part A is connected to the pattern part C. In addition, the weld bead formation is surely performed in the pattern portion C. For this reason, at the starting point of the completed weld bead, the weld bead is formed with a keyhole while moving the laser irradiation point.

  In addition, since the laser irradiation point is moved at the start of the laser irradiation in this way, it is possible to prevent perforation by a keyhole. This is because when a laser beam is applied at the starting point of laser irradiation without applying the heat necessary to form a weld bead, a powerful laser will be concentrated on one point, causing a hole in the keyhole. It becomes easy to do. In order to prevent such keyhole perforation, it is necessary to carry out while giving the amount of heat necessary for forming the weld bead, so that very fine laser intensity adjustment is required.

  In this respect, in this embodiment, since the laser irradiation point has moved from the start of laser irradiation, the member to be welded does not melt when the laser hits the member to be welded. However, since the laser is radiated between the introduction portions A, when the pattern portion C is reached, heat sufficient to form a weld bead enters. For this reason, the presence of the introduction portion A not only shortens the process time but also improves the welding quality. In addition, since the introduction part A is present, even in that part, the formation of the weld bead naturally occurs before the AE position that reaches the actual weld part, even if this place does not lead to complete weld bead formation. The weld bead length is increased accordingly. Accordingly, since the weld bead length can be increased without increasing the process time, the welding quality can be further improved.

  The mirror operation when drawing the introduction part A is preferably such that the direction of the introduction part A (arrow F in the figure) is the same as the moving direction of the laser irradiation device 3. That is, the direction in which the processing pattern is drawn is taught in advance so that the introduction portion A is the same as the moving direction of the laser irradiation device 3.

  Usually, the moving direction of the laser irradiation device 3 is moved from one welding point to the next welding point. For this reason, by setting the direction of the introduction part A to the direction toward the next welding point, there is no need to change the direction of the laser irradiation device 3 for welding, the movement trajectory of the laser irradiation device 3 is shortened, Accordingly, the entire process time can be shortened.

  Moreover, by doing in this way, even if this reflecting mirror 11 is stopped toward the starting point direction of the pattern for processing during this introduction part A, an introduction part will be drawn automatically, and then What is necessary is just to operate the reflective mirror 11 so that the pattern part C of a weld bead may be drawn. In this way, for example, as a mirror operation for drawing the pattern of the introduction part A, a very simple teaching can be performed by simply changing the direction of the reflection mirror 11 in one direction.

  On the other hand, the escape portion B has sufficient weld bead formation in the pattern portion C so far, so there is no problem even if the laser irradiation position is touched to some extent, and acceleration is started in the section of the escape portion B. The process time required for welding can be reduced even a little. The escape portion B may not be provided, and acceleration may be started after the machining pattern is completely drawn in the state where the robot 1 is completely stopped in this section.

  Further, since the pattern portion C is performed after the robot operation is completely stopped, there is no influence of the vibration of the robot or the bending of the arm, and a clean weld bead can be formed reliably. .

  Here, the difference between this embodiment and the case where laser irradiation is started after the operation of the robot 1 is completely stopped as in the prior art will be described.

  FIG. 7B is a timing chart according to the conventional operation shown for comparison with the present embodiment.

  In this case, when it is determined from the position data that the laser irradiation device 3 (head position) has reached B1, a deceleration command is issued together with a stop command. Then, after the robot 1 is completely stopped at the position B2, mirror operation and laser irradiation are started.

  Thereafter, after the reflecting mirror 11 reaches the welding end position, the mirror operation and the laser irradiation are stopped, and the operation of the robot 1 is started (acceleration command). After that, while controlling the speed (constant speed command), the process proceeds to the next welding point.

  The time for drawing the pattern for processing, that is, the time required for forming the weld bead is also the portion of the pattern portion C described in FIG. 8 in this embodiment. This is the time taken for A3 to A5 shown in FIG.

  In the conventional operation, the pattern of the weld bead to be formed is the pattern portion C, which is substantially the same as in this embodiment. The time taken is the time B2 to B3 in FIG. This time is longer than the time required for the pattern portion C in this embodiment. In order to apply a sufficient amount of heat to form a weld bead at the start of laser irradiation, it is necessary to have time to stop the movement of the laser and ensure a sufficient amount of heat input at the start of laser irradiation. It is because it has become.

  Thus, in this embodiment, since the robot 1 is not stopped for a time for applying a sufficient amount of heat to the member to be welded at the initial stage of forming the weld bead, the process time can be shortened by that amount compared to the conventional operation.

  Next, the procedure of the welding operation according to this embodiment will be described. Since the details of the welding operation are as described in the time chart already described, only the processing performed by the robot controller 7 will be described here.

  FIG. 9 is a flowchart showing a processing procedure of the robot control apparatus.

  The basic operation at the time of laser welding is to stop the robot 1 at the taught position, perform laser welding on one or a plurality of welding points that can be irradiated by the laser irradiation device 3 at that position, and set the next welding point. In the case of laser welding, the robot 1 is further moved to the next position to repeat laser welding. Here, a case where one welding point is welded as in the above-described term chart will be described as an example.

  The robot controller 22 first reads teaching data for laser welding (S1). The teaching data includes, for example, robot stop position, laser irradiation start position, operation speed (including acceleration rate, deceleration rate, constant speed, etc.), laser irradiation start position, laser irradiation end position, welding point center coordinates, processing pattern, The reflecting mirror moving speed and direction, welding width, welding length, laser output intensity, and other operation commands necessary for control are described. The robot 1 operates according to this.

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

  Subsequently, the robot control unit 22 operates the robot 1 according to the teaching data, and moves the laser irradiation device 3 at the operation speed described in the teaching data (S3).

  If it is determined that the position of the laser irradiation device 3 has reached the deceleration position (A1 in FIG. 7A, the same applies hereinafter) (S4: Yes), a deceleration command is output and deceleration is started (S5). .

  Subsequently, when it is determined that the laser irradiation device 3 has reached the laser irradiation start position (A2) (S6: Yes), mirror operation and laser irradiation are started (S7). Thereafter, since the laser irradiation device 3 stops at the stop position (A3), the mirror operation is continued to draw the processing pattern.

  Subsequently, when the reflecting mirror 11 reaches the escape position (A4) (S8: Yes), an acceleration command for the robot 1 is output and acceleration is started (S9). Subsequently, the mirror operation and the laser irradiation are stopped (S11) when the laser irradiation device 3 reaches the separation position (A5) (S10: Yes). After that, when the laser irradiation device 3 reaches the position (A6), it is controlled so as to become a constant speed (S12), and it goes to the next welding point (to S3).

  As described above, the case where one welding point is welded when the laser irradiation device 3 stops at one stop position has been described as the present embodiment, but the present invention is a case where such one welding point is welded. In addition to this, a plurality of welding points can be welded at one stop position. As already described, there is a reflection mirror 11 in the laser irradiation device 3, and a plurality of welding points can be welded as long as the movement of the reflection mirror 11 is within the range where the laser focus reaches from one stop position. .

  FIG. 10 is an explanatory diagram for explaining a weld bead formed when a plurality of welding points are welded.

  Here, a case where welding is performed using a C-shaped machining pattern will be described as an example. As shown in the drawing, first, welding is started on the first welding point 51. At this time, as described above, welding is started in the deceleration region of the robot 1 and a welding bead of the introduction part A is made. Thereafter, the robot 1 is stopped, and the pattern portion C is continuously drawn from the introduction portion A and is formed by drawing with a processing pattern. The pattern portion C is formed only by the movement of the reflection mirror 11. The first weld point 51 is formed with a weld bead while the robot 1 is stopped until the end of the pattern portion C.

  Then, while the robot 1 is stopped, the reflection mirror 11 is moved at high speed toward the next second welding point 52, and the weld bead formation of the pattern portion C of the second welding point 52 is performed. Therefore, at the second welding point 52, all of the weld beads are made of a processing pattern. The high-speed movement of the reflecting mirror 11 is a faster state in which the reflecting mirror is moved when forming the weld bead of the pattern portion C, and is so fast that the welded member does not melt even if a laser is applied to the welded member. It is a state.

  If the laser irradiation point reaches the end of the pattern portion C of the second welding point 52 following the first welding point 51, the welding of the second welding point 52 is completed, so the robot 1 is still stopped. The reflection mirror 11 is moved at high speed toward the next third welding point 53. When the laser irradiation point reaches the position before the end of the pattern portion C of the third welding point 53, the operation of the robot 1 is started and the movement of the laser irradiation device 3 is started. For this reason, at the third welding point 53, the weld bead of the escape portion B is formed at the end of the pattern portion C.

  Even when a plurality of welding points are welded from one stop position of the laser irradiation device 3 in this way, sufficient keyhole formation occurs at the first welding point 51 by the introduction portion A, and the welding strength also increases. Further, at the second welding point, a weld bead is formed by a machining pattern as in the conventional case. At the third welding point, the welding time can be shortened by taking the escape portion B. Therefore, the welding time can be shortened and the welding strength can be improved as a whole of the plurality of welding points.

  According to the present embodiment described above, the following effects can be obtained.

  When the laser irradiation device 3 is moved to the welding point of the member to be welded and stopped, laser irradiation is started from the middle of the movement toward the welding point, and after the laser irradiation device 3 is stopped, further laser irradiation is continued. A processing pattern was drawn. Thereby, the process time accompanying welding operation can be shortened. In addition, the length of the weld bead is longer than that of the conventional one due to the presence of the weld bead in the introduction portion formed in the deceleration region, and the weld quality is improved. Moreover, even if the weld bead is lengthened, the process time does not increase at all, and on the contrary, it can be shortened as compared with the prior art.

  In particular, since the laser irradiation is started at the deceleration region for stopping the laser irradiation device 3, the laser irradiation is started before the laser irradiation device 3 is completely stopped. Can be shortened.

  Further, at the end of welding, even if acceleration is started to move the laser irradiation device 3, laser irradiation may be continued to some extent, so that the robot operation is started early at the end of welding. Thus, the process time can be shortened accordingly.

  Further, the moving direction of the laser irradiation apparatus 3 from the start of laser irradiation to the stop of the laser irradiation apparatus 3 is made to coincide with the direction of the section (introduction part) to be welded at that time. Thereby, the operation of the reflecting mirror 11 can be reduced. Further, by making the moving direction of the laser irradiation device 3 toward the next welding point, there is no need to change the direction of the laser irradiation device 3 for welding, the movement trajectory is shortened, and the entire process time is reduced. Shortening can be achieved.

  Further, the finished weldment has a weld bead formed with a processing pattern after being stopped and a weld bead formed by irradiating a laser beam from a deceleration region in the middle of movement. Therefore, the weld bead becomes longer than before due to the presence of the introduction portion, and the welding quality is improved.

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 drawing which shows the example of the pattern for a process. It is explanatory drawing for demonstrating conversion of the pattern for a process to the coordinate system of the robot 1, and has shown the case of the S-shaped pattern. It is explanatory drawing for demonstrating conversion of the pattern for a process to the coordinate system of the robot 1, and has shown the case of the C-shaped putter. It is a time chart for demonstrating welding operation | movement, (a) is this embodiment, (b) is conventional operation | movement. It is explanatory drawing explaining the weld bead performed by welding operation. It is a flowchart which shows the process sequence of a robot control apparatus. It is explanatory drawing explaining the weld bead formed when welding of several welding points is performed.

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 scanning control unit,
26 ... instruction part,
100 ... Laser,
121 ... collimating lens,
122 ... Condensing lens.

Claims (6)

The laser irradiation means is moved to the welding point of the member to be welded , and laser irradiation is started from the laser irradiation means toward the welding point in the deceleration region for stopping the laser irradiation means in the middle of the movement, A laser welding method, wherein the laser irradiation means is stopped while continuing laser irradiation, and the laser irradiation is further continued after stopping the laser irradiation means. Further, acceleration is started to move the laser irradiation means again from the stop position, and the laser irradiation is continued until the laser irradiation means reaches a predetermined position. 2. The laser welding method according to 1. The laser irradiation means is moved to the welding point of the member to be welded, laser irradiation is started from the laser irradiation means toward the welding point in the middle of the movement, and the laser irradiation means is stopped while continuing the laser irradiation. , After stopping the laser irradiation means, continue laser irradiation,
Further, the laser welding is performed such that acceleration is started again to move the laser irradiation unit from the stop position, and the laser irradiation is continued until the laser irradiation unit reaches a predetermined position. Method.   The welding section irradiated with laser from the middle of the movement until the stop is used as an introduction section, and the welding direction of the introduction section is the same as the direction in which the laser irradiation means is moved. The laser welding method as described in any one of -3. A welded article welded by the laser welding method according to claim 1,
An introduction part formed by laser irradiation from the laser irradiation means toward the welding point from the middle of movement;
A weldment comprising a weld bead including a portion formed by drawing a predetermined processing pattern after stopping the laser irradiation means following the introduction portion weld bead. Transportation means;
Laser irradiation means attached to the moving means;
In order to weld the welding point of the member to be welded, the movement of the laser irradiation unit is started by the moving unit, laser irradiation is started from the laser irradiation unit toward the welding point in the middle of the movement, and the laser A control means for controlling the moving means and the laser irradiation means so as to continue the laser irradiation after stopping the laser irradiation means while continuing the irradiation, and stopping the laser irradiation means;
I have a,
The control means further continues the laser irradiation from the time when acceleration is started to move the laser irradiation means again from the stop position until the laser irradiation means reaches a predetermined position. Laser welding system characterized by

Images