Tailored Blank Welding Equipment

Abstract

To provide a tailored blank welding device capable of suppressing deterioration of weld quality compared with the past.SOLUTION: When a temperature change of a robot 20 exceeds a prescribed threshold, a control device 50 calculates a deviation amount of a welding target position by the robot 20 based on a processing result of a welding trajectory image by a camera 40, and corrects the welding target position of the robot 20. Therefore, even when the robot 20 is deformed owing to outdoor temperature change caused by seasonal fluctuation or linear expansion caused by heat generation during operation of the robot 20, deviation of the welding target position can be corrected, to thereby suppress deterioration of weld quality.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a tailored blank welding apparatus. [Background technology]

[0002] 2. Description of the Related Art There is a tailored blank welding apparatus that butts together workpieces having different plate thicknesses and materials and line-welds the butt joints to produce materials for pressing (tailored blanks) (see, for example, Patent Document 1).

[0003] The welding quality of tailored blanks is maintained by precisely irradiating the boundary between the butted workpieces with a laser. In particular, in tailored welding using robots, quality is controlled by fine adjustments of a few tenths of a millimeter through teaching work.

[0004] However, generally, robots are made of metal. Therefore, as shown in FIG. 7, the length of the robot arm 2a of the robot 2 changes from the state D1 shown by the solid line to the state D2 shown by the dotted line due to the linear expansion caused by the outside temperature fluctuation due to seasonal fluctuations and the heat generated by the motor during the operation of the robot. This is because it is difficult to keep the temperature inside the processing machine constant during welding due to equipment reasons, and it is also difficult to manufacture the robot 2 from materials with a small linear expansion coefficient. Therefore, the welding target position of the robot 2 shifts from the position T1 taught at the time shown by the solid line to the position T2 shown by the dotted line, exceeding the margin of the acceptable conditions for welding, and there is a risk of the welding quality being reduced. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2009-262193 A Summary of the Invention [Problem to be solved by the invention]

[0006] An object of the present invention is to provide a tailored blank welding device that can suppress deterioration in welding quality compared to conventional devices. [Means for solving the problem]

[0007] The present invention which achieves the above object is as follows. (1) a robot that butts first and second work pieces together and welds the butt joint; a temperature measuring device for measuring a temperature of the robot; A camera for capturing an image of the welding trajectory of the robot; A control device that controls the robot, the temperature measuring device, and the camera; having A tailored blank welding device in which, when a temperature change of the robot exceeds a predetermined threshold, the control device calculates an amount of deviation of the welding target position of the robot based on a processing result of the welding trajectory image taken by the camera, and corrects the welding target position of the robot. (2) The tailored blank welding device according to (1), wherein a correction value is automatically input to the control device based on the deviation amount of the welding target position. Effect of the Invention

[0008] According to the tailored blank welding device of (1) above, when the temperature change of the robot exceeds a predetermined threshold, the control device calculates the amount of deviation of the welding target position of the robot based on the processing result of the welding trajectory image by the camera, and corrects the welding target position of the robot, so that even if the robot deforms due to seasonal changes in outside temperature or linear expansion due to heat generation while the robot is in operation, the deviation of the welding target position can be corrected, thereby preventing deterioration of welding quality.

[0009] According to the tailored blank welding device of (2) above, a correction value is automatically input to the control device based on the amount of deviation of the welding target position, eliminating the need to re-teach the robot every time the welding target position deviates, thereby improving the productivity of tailored blanks. [Brief description of the drawings]

[0010] [Figure 1] 1 is a schematic diagram of a tailored blank welding apparatus according to an embodiment of the present invention; FIG. [Diagram 2] 1 is a partial plan view of first and second workpieces to be welded by a tailored blank welding apparatus according to an embodiment of the present invention. FIG. [Diagram 3] FIG. 2 is a side view showing the relationship between the laser light of the robot and the imaging direction of the camera in the tailored blank welding device according to the embodiment of the present invention. [Figure 4] FIG. 2 is a diagram showing an image captured by a camera of the tailored blank welding device according to an embodiment of the present invention. [Diagram 5] FIG. 13 is a diagram for explaining that the amount of deviation due to linear expansion at each teaching point differs depending on the posture of the robot during welding in the tailored blank welding apparatus according to the embodiment of the present invention. [Figure 6] 4 is a flowchart showing a control routine of a control device in the tailored blank welding apparatus according to the embodiment of the present invention. [Figure 7] FIG. 1 is a schematic diagram of a conventional tailored blank device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A tailored blank welding apparatus (hereinafter, also simply referred to as a welding apparatus) 10 according to an embodiment of the present invention will be described below with reference to the drawings.

[0012] 2, the welding device 10 is a device for butting first and second workpieces 101, 102 made of, for example, steel plates having different plate thicknesses and materials, and line-welding the butted portion (butt joint 103) to manufacture a single press material (tailored blank). The material manufactured from the first and second workpieces 101, 102 is not particularly limited, but is used, for example, for automobile bodies for the purpose of reducing the weight of automobiles.

[0013] As shown in FIG. 1, the welding apparatus 10 includes a robot 20 that laser welds the first and second work materials 101, 102 in a line along the butt joint 103 of the first and second work materials 101, 102, a temperature measuring device 30 that measures the temperature of the robot 20, a camera 40 that captures an image of the welding trajectory TR of the butt joint 103, and a control device 50 that controls the robot 20, the temperature measuring device 30, and the camera 40.

[0014] The robot 20 has been taught in advance, and laser welds the first and second workpieces 101, 102 along the butt joint 103 through this teaching. The robot 20 has a robot arm 23 that is connected to a base 21 at its base end and has a laser head 22 attached to its tip end. The robot arm 23 is a multi-joint arm that has first and second joints 23a, 23b and upper and lower arm portions 23c, 23d. The robot arm 23 has multiple built-in servo motors (not shown), and the laser head 22 can be moved and operated three-dimensionally by driving the robot arm 23 with the servo motors.

[0015] As shown in FIG. 3, the laser head 22 irradiates the laser light L output from a laser oscillator (not shown) onto the butt joint 103 of the first and second workpieces 101 and 102. The laser head 22 has a collimator lens 22a that converts the laser light L into parallel light, and a condenser lens 22b that condenses the parallel light so as to form a focus at the butt joint 103. The laser head 22 also has a reflector (not shown) that can be rotated by a servo motor (not shown). The laser light L output from the laser oscillator (not shown) passes through both lenses 22a and 22b, is reflected by the reflector, and is irradiated onto the butt joint 103. By rotating the reflector by the servo motor, the laser light L can be rotated so as to follow a circular orbit. The control device 50 controls the robot arm 23 and the laser head 22, so that the irradiation position of the laser light L can be moved in a spiral shape along the butt joint 103.

[0016] 1, the temperature measuring device (thermometer) 30 is capable of measuring the temperature of the robot arm 23. The temperature measuring device 30 measures the temperature of the upper arm portion 23c and / or the lower arm portion 23d of the robot arm 23. The temperature measuring device 30 may be a contact type such as a thermocouple, or a non-contact type such as an infrared radiation thermometer.

[0017] Camera 40 can capture an image of the laser-welded portion of butt joint 103 and its surroundings. Therefore, it can capture an image of at least a part of the welding locus TR of butt joint 103. When welding a preset teaching point (image capture point), camera 40 captures an image of an area including the teaching point. A plurality of teaching points are set on the line of butt joint 103, and for example, 25 points are set, with the numbers 1 to 25 circled in FIG. 2. The number and intervals of the teaching points can be set arbitrarily.

[0018] As shown in Fig. 3, the camera 40 is attached to the laser head 22. The camera 40 captures an image of the welding locus TR of the butt joint 103 via first and second imaging mirrors 41, 42 that reflect the welding locus TR of the butt joint 103. Information on the image captured by the camera 40 is transmitted to the control device 50 via an image processing amplifier 43 as shown in Fig. 1.

[0019] The control device (which may be called a robot control panel) 50 controls the welding target position of the robot 20 based on teaching performed in advance. The control device 50 also calculates the amount of deviation of the actual welding position from the welding target position A previously taught to the robot 20 based on the processing result of the welding trajectory TR image taken by the camera 40, and can correct the welding target position of the robot 20 by automatically inputting a correction value based on the calculation result.

[0020] The reason for calculating (measuring) the amount of deviation based on the processing result of the welding trajectory image by the camera 40 is as follows. Figure 5 shows (a) the robot 20, (b) multiple teaching points 1 to 11, and (c) to (e) graphs showing the posture of the robot 20 at points 1, 4, and 9 of the multiple teaching points 1 to 11 and the amount of deviation due to linear expansion when using the robot 20 to laser weld the butt joints of first and second work materials 101' and 102' that are different from the first and second work materials 101 and 102.

[0021] 5(c) to (e), it can be seen that the robot 20 takes various postures during welding, and the amount of deviation due to linear expansion at each teaching point 1, 4, 9 varies depending on the posture of the robot 20. Therefore, it is not possible to deal with it by uniform correction, and it is effective to actually calculate (measure) the amount of deviation at each point. Therefore, the amount of deviation is calculated (measured) based on the processing result of the welding trajectory TR image by the camera 40.

[0022] Fig. 6 is a flowchart showing a control routine of the control device 50. The control routine shown in Fig. 6 is performed at predetermined time intervals while laser welding (welding processing) is being performed.

[0023] First, after the start of laser welding, in step S1, the temperature of the robot 20 is measured using the temperature measuring device 30, and the process proceeds to step S2. In step S2, it is determined whether or not the temperature change of the robot 20 exceeds a predetermined threshold. If it is determined in step S2 that the temperature change does not exceed the predetermined threshold, the process proceeds directly to the end step without correcting the deviation of the welding target position. On the other hand, if it is determined in step S2 that the temperature change exceeds the predetermined threshold, the process proceeds to step S3.

[0024] In step S3, the welding trajectory TR is imaged using the camera 40, and the process proceeds to step S4, where the amount of deviation is calculated (measured) and acquired based on the image information captured by the camera 40. Then, in step S5, a correction value is automatically input to the control device 50 in a direction to eliminate the amount of deviation, and the process proceeds to the end step.

[0025] Next, the operation and effects of the embodiment of the present invention will be described. In this embodiment of the present invention, when the temperature change of the robot 20 exceeds a predetermined threshold value, the control device 50 calculates the amount of deviation of the welding target position of the robot 20 based on the processing results of the welding trajectory image taken by the camera 40, and corrects the welding target position of the robot 20. Therefore, even if the robot 20 deforms due to seasonal changes in outside temperature or linear expansion due to heat generation while the robot 20 is in operation, the deviation of the welding target position can be corrected and a decrease in welding quality can be suppressed.

[0026] In addition, since a correction value is automatically input to the control device 50 based on the amount of deviation of the welding target position, it is not necessary to redo teaching of the robot 20 every time the welding target position deviates, thereby improving the productivity of tailored blanks. [Explanation of symbols]

[0027] 10 Tailored blank welding equipment 20. Robot 22 Laser Head 23 Robot Arm 30 Temperature measuring device 40 Camera 43 Image Processing Amplifier 50 Control device 101, 102 First and second work pieces 103 Butt joint L Laser light TR welding trajectory

Claims

[Claim 1] a robot that butts the first and second work pieces together and welds the butt joint; a temperature measuring device for measuring a temperature of the robot; A camera for capturing an image of the welding trajectory of the robot; A control device that controls the robot, the temperature measuring device, and the camera; having When the temperature change of the robot exceeds a predetermined threshold, the control device calculates an amount of deviation of a welding target position of the robot based on a processing result of the welding trajectory image taken by the camera, and corrects the welding target position of the robot; A correction value is automatically input to the control device based on the deviation amount of the welding target position, A tailored blank welding apparatus, wherein the camera captures an image of the welding trajectory via an imaging mirror.

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