Automatic arc welding equipment

Abstract

To prevent arc light from a welding portion from interfering with laser reflection light, and to enable highly accurate follow-up control by correctly detecting the position of a joint part of two metal members.SOLUTION: An automatic arc welding device includes: a sensor head 10 for receiving reflection light LR of emission light LS with respect to the vicinity of a joint part between metal plates M1, M2; a welding torch 17 integrally moving with the sensor head 10; a control part for detecting the position to be welded of the joint part from the reflection light LR received by the sensor head 10, and for controlling the movement position of the welding torch 17 based on the welding reference position Pn acquired from the position detection value; and a light shielding part 14S including a light shielding cover 14, a throttle part 15 and a slit part 16 formed in a cylindrical shape so as to surround an optical axis of the reflection light LR entering the light receiving part 12 of the sensor head 10. Arc light AL which has been generated from the welding portion and has entered the light shielding cover 14 entering the light receiving part 12 is prevented by the light shielding cover 14.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an automatic arc welding device that uses a position sensor such as a laser sensor to recognize the position and shape of the joint between two metal members, and controls the movement position (movement path) of a welding torch based on this information. [Background technology]

[0002] When welding two metal components together, a deviation may occur between a preset welding position and the actual position to be welded due to the presence of gaps or steps at the joint between the metal components, thermal deformation during welding, etc. As a countermeasure to the above problem, a tracking control has been conventionally known in which the shape and position of the joint are detected from the reflected light of a position-detecting laser light emitted from a laser sensor toward the joint, and the feed (movement path) of the welding torch is controlled based on this information.

[0003] However, if some of the arc light generated from the welding site mixes with the reflected laser light used for position detection and is received by the laser sensor, the shape and position of the joint cannot be accurately grasped, resulting in an unstable tracking control. One possible solution to this problem is to use a bandpass filter or the like to remove the wavelengths of the arc light and extract only the reflected laser light. However, if the wavelength region of the arc light, which has a high radiation intensity, overlaps with the wavelength region of the reflected laser light, this type of solution is difficult to implement.

[0004] As prior art for monitoring the melting state and controlling the welding device using captured images of the welded portion, the techniques disclosed in Patent Documents 1 and 2, for example, are known. That is, Patent Document 1 describes a technique in which an image of a welded portion directly below a welding wire is captured by an imaging device, and a specific band of wavelengths is detected from the image to determine whether the welded state is appropriate. Patent Document 2 also describes a technology in which the tip position of the welded portion and the end position of the welded material that defines the root gap are detected from an image of the welded portion of a groove having a root gap (groove gap), and welding conditions such as the welding speed and welding current are controlled based on the positional relationship (distance) between the tip position and the end position. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2020-171967 A (

[0011] to

[0033] ,

[0039] to

[0042] , Figure 1, etc.) [Patent Document 2] JP 2020-28889 A (

[0026] to

[0037] , Figs. 3 to 8, etc.) Summary of the Invention [Problem to be solved by the invention]

[0006] In Patent Document 1, if the amount of arc light incident on the imaging device is too much or too little, the captured image becomes unclear and it becomes difficult to accurately recognize the melted state, so it is necessary to carefully select the central transmission wavelength, etc. of the optical filter implemented in front of the imaging device. In addition, in Patent Document 2, the aim is to obtain a good reverse bead by detecting the positional deviation between the tip position of the molten part and the end position of the welded material and correcting the welding speed, welding current, etc., but the tip position of the molten part may become unclear due to the influence of the arc light reflected in the captured image, making it impossible to accurately measure the positional deviation.

[0007] Therefore, the problem to be solved by the present invention is to provide an automatic arc welding device that prevents the arc light generated from the welding site from interfering with position detection light such as reflected laser light, accurately detects the position of the joint between two metal parts to be welded, and enables high-precision trajectory tracking control by moving the welding torch in accordance with the detected position. [Means for solving the problem]

[0008] In order to solve the above problem, the invention according to claim 1 comprises: a light emitting unit that emits a position detection light near a joint between two metal members; a light receiving section that receives reflected light of the position detection light reflected near the joint; a welding torch that is movable integrally with the light receiving unit; a control unit that detects a position to be welded at the joint from the reflected light received by the light receiving unit and controls a moving position of the welding torch based on the position detection value; a light-shielding portion that prevents the arc light generated at the joint from being incident on the light-receiving portion; Equipped with The light blocking portion is a cylindrical light-shielding cover formed to surround the optical axis of the reflected light; a diaphragm portion provided on the light-shielding cover so as to intersect with an optical axis of the reflected light and having a space having a cross-sectional area equal to or smaller than a cross-sectional area of ​​the light-shielding cover; Equipped with 、 The optical axis of the reflected light passing through the space of the diaphragm intersects with the optical axis of the arc light at a predetermined angle. It is characterized by:

[0010] Claim 2 The invention relates to a light emitting unit that emits a position detection light near a joint between two metal members; a light receiving section that receives reflected light of the position detection light reflected near the joint; a welding torch that is movable integrally with the light receiving unit; a control unit that detects a position to be welded at the joint from the reflected light received by the light receiving unit and controls a moving position of the welding torch based on the position detection value; a light-shielding portion that prevents the arc light generated at the joint from being incident on the light-receiving portion; Equipped with The light blocking portion is a cylindrical light-shielding cover formed to surround the optical axis of the reflected light; a diaphragm portion provided on the light-shielding cover so as to intersect with an optical axis of the reflected light and having a space having a cross-sectional area equal to or smaller than a cross-sectional area of ​​the light-shielding cover; Equipped with The light-shielding cover has a matte finish formed on at least a portion of its inner surface for absorbing the arc light that has entered the light-shielding cover and preventing its reflection.

[0011] Claim3 The invention according to claim 1 OR 2 In the automatic arc welding apparatus described in the above, the narrowing portion is formed at the joint side end of the light-shielding cover and is provided with a slit portion that forms the space.

[0012] Claim 4 The invention according to claim 3 In the automatic arc welding apparatus described in the above, the opening area of ​​the slit portion is made adjustable.

[0013] Claim 5 The invention according to claim 3 or 4 In the automatic arc welding apparatus described in the above, the slit portion has an oblique slit that is obliquely aligned along the optical axis of the reflected light incident on the light receiving portion.

[0014] Claim 6 The invention relates to claims 1 to 5 In the automatic arc welding apparatus described in any one of claims 1 to 5, a sensor / welding unit including the light receiving unit, the light shielding cover and the welding torch is moved as a unit via a robot mechanism controlled by the control unit. Effect of the Invention

[0015] In the present invention, the light-shielding section, which is equipped with a light-shielding cover and a diaphragm, prevents interference between the position detection light from the joint between two metal members and the arc light generated from the welded part, thereby preventing the arc light from entering the light-receiving section. This allows only the position detection light to enter the light-receiving section, accurately recognizing the position of the joint, and allows the movement path of the welding torch performing arc welding to be set with high precision and controlled to follow it. [Brief description of the drawings]

[0016] [Figure 1] 1A and 1B are configuration diagrams of main parts of an automatic arc welding device according to an embodiment of the present invention, where (a) is a front view and (b) is a side view. [Diagram 2]2 is an enlarged cross-sectional view showing a schematic configuration example of a slit portion in FIG. 1. FIG. [Diagram 3] 5A and 5B are diagrams for explaining measurement positions, welding positions, etc. when tracking control is performed in an embodiment of the present invention, where (a) is a front view and (b) is a side view. [Figure 4] FIG. 4 is an explanatory diagram of detection positions A to D and a welding reference position Pn at each of measurement positions S1, S2, S3, . . . in FIG. [Diagram 5] FIG. 3(a) shows measurement data for detection positions A to D when arc welding is performed in the measurement range along the x direction in FIG. 3(a), where (a) shows the case without the light-shielding cover and (b) shows the case with the light-shielding cover according to this embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. First, FIG. 1 is a configuration diagram of a main part of an automatic arc welding device according to this embodiment, where (a) is a front view and (b) is a side view.

[0018] In these figures, a sensor head 10 has a built-in laser sensor as a position sensor for detecting the position and shape of the joint of the workpieces. The laser sensor emits light L, which is a laser beam of a predetermined wavelength. S A light emitting unit 11 emits light perpendicularly to the workpieces to be welded, and reflected light L from the workpieces to be welded. R The sensor head 10 is provided with a light receiving section 12 that receives the light. The light receiving section 12 is disposed at the rear of the lower end of the sensor head 10. It is not necessary that the light emitting unit 11 and the light receiving unit 12 are integrated by the sensor head 10. For example, the light emitting unit 11 may be separated from the light receiving unit 12 and operated independently.

[0019] M1 and M2 are metal plates as members to be welded, and the automatic arc welding device of this embodiment is used to weld the metal plates M1 and M2 together to manufacture, for example, the bottom of a box-shaped tank. Here, the metal plate M1 constitutes the side plate of the tank, and the metal plate M2 constitutes the bottom plate of the tank. The vicinity of the joint between these metal plates M1 and M2 is detected by the emitted light L of the laser sensor. S and reflected light L R The measurement position S is determined by using the output light L S and reflected light L R has a predetermined width in the y direction in FIG. In addition, reflected light L R is configured to be reflected at an angle α of, for example, 25° and enter the light receiving unit 12.

[0020] A light-shielding cover 14 having a substantially rectangular cylindrical shape is fixed below the light-receiving portion 12 of the sensor head 10. The light-shielding cover 14 has a central axis that faces the reflected light L R The light-shielding cover 14 may be substantially cylindrical. Reflected light L R The light is introduced into the light-shielding cover 14 through a slit portion 16 provided in a narrowing portion 15 at the lower end of the light-shielding cover 14 , and enters the light-receiving surface 12 a of the light-receiving portion 12 . Here, the light-shielding cover 14, the aperture portion 15, and the slit portion 16 configure a light-shielding portion 14S.

[0021] In addition, the arc light A generated from the welding position P described later L There is a possibility that a part of the arc light A may pass through the slit portion 16 and enter the light-shielding cover 14. L and reflected light L R The inclination angle of the light shielding cover 14 and the opening area of ​​the slit portion 16 are adjusted so that the optical axis of the arc light A entering the light shielding cover 14 is not parallel to that of the arc light B. L does not reach the light receiving unit 12. In particular, the arc light A is incident on the inner surface of the light-shielding cover 14. LIf a matte-finished portion 14a is formed to absorb the arc light A and prevent its reflection, the arc light A incident on the light-receiving portion 12 can be prevented from being reflected. L The amount of light entering the light-shielding cover 14 from the slits 16 can be reduced to almost zero. L It is sufficient to form it in the area where it directly hits.

[0022] FIG. 2 is an enlarged cross-sectional view showing a schematic example of the configuration of the throttle portion 15 and the slit portion 16. As shown in FIG. In FIG. 2(a), the slit portion 16A reflects light L R 2(b) is provided with a diagonal slit 16x that is diagonal along the optical axis of the slit 16. The slit section 16B of FIG. 2(b) is provided with a vertical slit 16y in which the opposing surfaces of the slit plates 16c and 16d are formed vertically. The oblique slits 16x and the vertical slits 16y are continuous with the inside of the narrowed portion 15 as well. The oblique slits 16x and the vertical slits 16y are arranged to reflect the reflected light L R It is preferable that the opening area can be adjusted by moving the slit plates 16a to 16d in the directions of the arrows in Figures 2(a) and (b) using an appropriate mechanism. Here, the cross-sectional area of ​​the oblique slits 16x and the vertical slits 16y as the space held by the diaphragm portion 15 as viewed in the z direction is equal to or smaller than the cross-sectional area of ​​the light-shielding cover 14.

[0023] The vertical slit 16y in FIG. 2(b) has a simple structure and is easy to manufacture. In contrast, the reflected light L R Even if the opening areas of the upper and lower portions of the slits obliquely aligned along the optical axis of the vertical slit 16y are the same as those of the vertical slit 16y, the arc light A passing through the oblique slit 16x and entering the light-shielding cover 14 is L The cross-sectional area of ​​the light beam of the arc A LTherefore, the amount of light incident on the light receiving section 12 can be reduced by the vertical slit 16y. L It is possible to further reduce the

[0024] Returning to Fig. 1, 17 denotes a welding torch. This welding torch 17 is integrally formed with the head fixing portion 13, the sensor head 10, the light-shielding cover 14, the aperture portion 15, the slit portion 16, etc., using a holding member not shown, and these as a whole constitute a sensor / welding unit U. This sensor / welding unit U can move in three directions (x, y, z directions) by controlling the operation of the robot mechanism with a control portion that implements hardware such as a CPU and memory and a predetermined program.

[0025] As shown in FIG. 1(a), the welding position P of the joint between the metal plates M1 and M2 is located behind the measurement position S in the x direction, and the distance d0 between the measurement position S and the welding position P is preferably 100 mm or less, and in this embodiment is set to about 40 mm. As shown in FIG. 1(a), the welding torch 17 is in the range of 0° to 70°, preferably in the range of 0° to 50° or less, with respect to the vertical axis, and the reflected light L R It is necessary to arrange the welding tool at an angle β so that the angle β does not interfere with the welding work and does not impede the welding. The angle β shown in Fig. 1(a) is, for example, 40°.

[0026] In FIG. 1(a), N denotes an obstacle such as a pipe protruding from a metal plate M2. Since the sensor / welding unit U can move horizontally (x and y directions), when an obstacle N is present, the sensor / welding unit U must be driven while adjusting its height in the z direction so that the aperture portion 15 and slit portion 16 (16A, 16B) of the light-shielding cover 14 do not collide with the obstacle N.

[0027] In the above configuration, the shapes and structures of the sensor head 10, the light-shielding cover 14, the aperture section 15, the slit section 16 (16A, 16B), etc. are not limited to those shown in the figures, and can be changed as desired without departing from the gist of the present invention. For example, the planar shape of the slit section 16 is not particularly limited, and may be a perfect circle, an ellipse, a rectangle, a regular polygon, etc.

[0028] As described above, in this embodiment, the light-shielding cover 14 fixed to the lower end of the sensor head 10 blocks the reflected light L R is made to enter the light receiving section 12 through the slit section 16, while the arc light A L The structure is such that the arc light A on the inner surface of the light-shielding cover 14 is not incident on the light-receiving portion 12. L By forming a matte finish portion 14a in the area where the arc light A directly hits, L The arc light A entering the light receiving section 12 is absorbed to prevent its reflection. L has been reduced as much as possible. With the above configuration, the laser sensor detects the reflected light L R Based on only this information, the height, width, shape, etc. of the joint between the metal members M1, M2 at the measurement position S can be accurately recognized, and the movement position of the welding position P by the welding torch 17 can be determined based on this information.

[0029] Next, Fig. 3 is an explanatory diagram of the measurement positions, welding positions, etc. when tracking control is performed in this embodiment, (a) is a front view, and (b) is a side view. Also, Figs. 4(a) and (b) are detection positions A to D and welding reference position P at the measurement positions S1, S2, S3, ... in Fig. 3(a). n 1 is a cross-sectional view for explaining a joint between metal plates M1 and M2. In FIG. 3(a), the position of the welding torch 17 is shifted rearward from that in FIG. 1(a) to prevent complication, and the overall view is simplified.

[0030] As shown in Fig. 3(a), when the movement direction (welding direction) of the sensor-welding unit U is the x direction, the measurement position by the laser sensor moves from S1 to S2 to S3, etc. For example, at measurement position S1, the laser sensor acquires the coordinates of positions A to D in Fig. 4(a) or (b) and stores these in memory. Here, Fig. 4(a) shows a case where the joint between the metal plates M1 and M2 is in close contact and the heights are uniform, and Fig. 4(b) shows a case where there is a gap at the joint and the heights of the metal plates M1 and M2 are misaligned.

[0031] In the control unit of the sensor / welding unit U, regardless of whether the state of the joint at the measurement position S1 is as shown in Fig. 4(a) or (b), the control unit calculates the center position of the joint from the x-coordinate of the detection positions A and B, and calculates the maximum height of the joint from the z-coordinate of the detection positions C and D. Then, the control unit calculates the intersection of the center position and the maximum height, and stores this in memory as the welding reference position P1 of the measurement position S1. The above operation is repeated each time the measurement position moves to S2, S3, . . . , and the welding reference positions P2, P3, . The welding reference position P n By controlling the operation of the robot mechanism so that the actual welding position P of the electrode tip of the welding torch 17 always follows the position (n=1, 2, 3, ...) of the metal plates M1 and M2, the metal plates M1 and M2 can be reliably welded together regardless of the state of the joint as shown in Figures 4(a) and (b).

[0032] Next, FIG. 5 shows measurement data for detection positions A to D in FIG. 4(b) when arc welding is performed over a specified measurement range along the x direction in FIG. 3, where FIG. 5(a) shows the case where there is no light-shielding cover 14 and FIG. 5(b) shows the case where there is a light-shielding cover 14 in this embodiment. Generally, the surfaces of the metal plates M1 and M2 have minute irregularities and deformations, so that the measurement values ​​at the detection positions A to D measured using a laser sensor do not form a straight line.

[0033] In particular, when welding is performed without the light-shielding cover 14, the reflected light L of the laser beam is received by the light receiving portion 12 of the laser sensor. R With arc light A L Since a part of the arc light A L As a result, the welding reference position P n It becomes impossible to accurately calculate, and tracking control of the welding torch 17 becomes difficult.

[0034] In contrast, when welding is performed with the light-shielding cover 14 attached to the sensor head 10, the arc light A L 5(b), the detection positions A to D can be obtained almost accurately with some noise removed. n This enables highly accurate tracking control. In addition, d1 and d2 in FIGS. 5(a) and 5(b) indicate the maximum region in which multiple erroneous position detection operations occur consecutively, and the reliability of this embodiment is evident from d1>d2.

[0035] As described above, according to this embodiment, the position at which metal components should be welded can be accurately detected using only the reflected laser light from which the arc light has been removed, thereby improving the accuracy of tracking control and increasing the yield of welded products. [Explanation of symbols]

[0036] 10: Sensor head 11: Light emitting part 12: Light receiving part 12a: Light receiving surface 14: Blackout cover 14a: Matte finish 14S: Light shielding part 15: Squeezing section 16, 16A, 16B: Slit section 16a, 16b, 16c, 16d: Slit plate 16x: Diagonal slit 16y: Vertical slit 17: Welding torch 18: Retaining member L S :Outgoing light L R :Reflected light A L :Arc light A, B, C, D: Detection position S, S1, S2, S3: Measurement position P: Welding position P n : Welding reference position M1,M2: Metal plate N: Obstacle U: Sensor / welding unit

Claims

1. a light emitting unit that emits a position detection light near a joint between two metal members; a light receiving section that receives reflected light of the position detection light reflected near the joint; a welding torch that is movable integrally with the light receiving unit; a control unit that detects a position to be welded at the joint from the reflected light received by the light receiving unit and controls a moving position of the welding torch based on the position detection value; a light-shielding portion that prevents the arc light generated at the joint from being incident on the light-receiving portion; Equipped with The light blocking portion is a cylindrical light-shielding cover formed to surround the optical axis of the reflected light; a diaphragm portion provided on the light-shielding cover so as to intersect with an optical axis of the reflected light and having a space having a cross-sectional area equal to or smaller than a cross-sectional area of ​​the light-shielding cover; Equipped with an optical axis of the reflected light passing through the space of the throttle portion intersects with an optical axis of the arc light at a predetermined angle.

2. a light emitting unit that emits a position detection light near a joint between two metal members; a light receiving section that receives reflected light of the position detection light reflected near the joint; a welding torch that is movable integrally with the light receiving unit; a control unit that detects a position to be welded at the joint from the reflected light received by the light receiving unit and controls a moving position of the welding torch based on the position detection value; a light-shielding portion that prevents the arc light generated at the joint from being incident on the light-receiving portion; Equipped with The light blocking portion is a cylindrical light-shielding cover formed to surround the optical axis of the reflected light; a diaphragm portion provided on the light-shielding cover so as to intersect with an optical axis of the reflected light and having a space having a cross-sectional area equal to or smaller than a cross-sectional area of ​​the light-shielding cover; Equipped with An automatic arc welding device, characterized in that a matte-finished portion is formed on at least a portion of an inner surface of the light-shielding cover to absorb the arc light that has entered the light-shielding cover and prevent its reflection.

3. 3. The automatic arc welding apparatus according to claim 1 or 2, The automatic arc welding device is characterized in that the narrowing portion is formed at the joint side end of the light-shielding cover and has a slit portion that forms the space.

4. 4. The automatic arc welding apparatus according to claim 3, An automatic arc welding device characterized in that the opening area of ​​the slit portion is adjustable.

5. 5. The automatic arc welding apparatus according to claim 3 or 4, An automatic arc welding device characterized in that the slit portion has an oblique slit that is oblique along the optical axis of the reflected light incident on the light receiving portion.

6. In the automatic arc welding apparatus according to any one of claims 1 to 5, an automatic arc welding device characterized in that a sensor / welding unit including the light receiving unit, the light shielding cover and the welding torch is moved as a unit via a robot mechanism controlled by the control unit.

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