Robotic system

Abstract

A robot system (1) comprises: a robot (2) having a wrist mechanism (9) and a flange (12) at the front end of the wrist mechanism (9) that can rotate around a rotation axis (G); a welding gun (3) fixed to the flange (12) by a welding gun bracket; and a welding sensor (4) fixed to the welding gun (3) and pre-detecting a welding line welded by the welding gun (3), wherein the welding sensor (4) is arranged between the flange (12) and the fixed position of the welding gun (3) on the welding gun bracket at a position capable of scanning a laser beam along a plane parallel to the rotation axis (G) in a direction intersecting the welding line, and the welding gun (4) has a tubular welding gun body that is arranged to protrude further toward the front end than the fixed position, and is bent at least twice so that a welding wire (51) protrudes from the front end in a direction parallel to the rotation axis (G).

Description

Technical Field

[0001] The present disclosure relates to a robot system. Background Art

[0002] As is well known, welding torches used for arc welding with robots typically have a curved torch body (see, for example, Patent Document 1). This curved shape bends the welding wire passing through the torch body, thereby ensuring stable contact between the inner surface of the power supply chip located at the front end of the torch body and the welding wire, and thus stabilizing the generated arc.

[0003] Furthermore, a real-time tracking technology is known in which the position and state of a weld line to be welded are detected in advance by scanning a laser beam, and welding is performed by a robot along the detected weld line (for example, see Patent Document 2).

[0004] In Patent Document 2, a welding sensor is arranged in parallel with a welding gun body in front of the welding gun body in the moving direction of the welding gun body by the robot.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Laid-Open No. 2009-34746

[0008] Patent Document 2: Japanese Patent Application Laid-Open No. 10-244367 Summary of the Invention

[0009] Problems to be solved by the invention

[0010] When welding sensors are arranged in parallel near the front end of a welding gun body, as described in Patent Document 2, there is a high probability that the welding sensors will interfere with the workpiece when the welding gun body is brought close to the workpiece. In this case, by arranging the welding sensors sufficiently set back from the front end of the welding gun body, interference around the front end of the welding gun body can be reduced.

[0011] However, because the welding gun body is curved in one direction, even if the welding sensor is positioned sufficiently back from the front end of the welding gun body, in order to scan the laser beam adjacent to the welding gun body, the welding sensor must be positioned significantly away from the central axis of the welding gun body. As a result, the welding sensor protrudes further from the welding gun body, further increasing the possibility of interference between the welding sensor and peripheral equipment.

[0012] Therefore, it is desired to detect the position and state of the weld line without causing the welding sensor to significantly protrude from the central axis of the welding gun body.

[0013] Solutions for solving problems

[0014] One aspect of the present disclosure is a robot system comprising: a robot having a wrist mechanism, wherein a flange rotatable about a rotation axis is provided at a front end of the wrist mechanism; a welding gun fixed to the flange by a welding gun bracket; a welding sensor fixed to the welding gun and pre-detecting a weld line welded by the welding gun, the welding sensor being arranged between the flange and a fixed position of the welding gun on the welding gun bracket at a position capable of scanning a laser beam in a direction intersecting the weld line along a plane parallel to the rotation axis, the welding gun having a tubular welding gun body, the welding gun body being arranged to protrude further toward the front end than the fixed position, and being bent at least twice so that a welding wire protrudes from the front end in a direction parallel to the rotation axis. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 1 is a diagram showing the overall structure of a robot system according to one embodiment of the present disclosure.

[0016] Figure 2 It shows Figure 1 A side view of the robot's wrist unit, welding gun, and welding sensor in the robotic system.

[0017] Figure 3 It shows Figure 2 Top view of the wrist unit, welding gun and welding sensor.

[0018] Figure 4 It shows Figure 2 A side view of a wrist unit, a welding gun, and a welding sensor in a first variation of the robot system.

[0019] Figure 5 It shows Figure 2 A side view of a wrist unit, a welding gun, and a welding sensor in a second variation of the robot system.

[0020] Figure 6 It shows Figure 5 Top view of the wrist unit, welding gun and welding sensor.

[0021] Figure 7 It shows Figure 5 Front view of the wrist unit, welding gun and welding sensor.

[0022] Figure 8 Yes Figure 5 A bottom view illustrating a modified example of mounting a welding gun and a welding sensor to a flange. DETAILED DESCRIPTION

[0023] Hereinafter, a robot system 1 according to an embodiment of the present disclosure will be described with reference to the drawings.

[0024] like Figure 1 As shown, a robot system 1 according to the present embodiment includes a robot 2 , a welding gun 3 and a welding sensor 4 attached to a distal end of a wrist mechanism 9 of the robot 2 .

[0025] The robot 2 may be, for example, a vertical six-axis articulated robot, and includes a base 5 installed on a mounting surface F such as the ground, a rotating body 6 supported relative to the base 5 so as to be rotatable about a first axis A, and a first arm 7 supported relative to the rotating body 6 so as to be rotatable about a second axis B. Furthermore, the robot 2 includes a second arm 8 supported relative to the first arm 7 so as to be rotatable about a third axis C parallel to the second axis B, and a three-axis wrist unit 9 (wrist mechanism). The three-axis wrist unit 9 is disposed at the distal end of the second arm 8.

[0026] The wrist unit 9 includes a first wrist element 10 rotatable relative to the second arm 8 about a fourth axis D, and a second wrist element 11 rotatable relative to the first wrist element 10 about a fifth axis E perpendicular to the fourth axis D. Furthermore, the wrist unit 9 includes a disc-shaped third wrist element (hereinafter referred to as a flange) 12 rotatable about a sixth axis (rotation axis) G, which passes through the intersection of the fourth axis D and the fifth axis E and is perpendicular to the fifth axis E.

[0027] An insulating adapter 13 made of an electrically insulating material is fixed between the flange 12 and the welding torch 3 . The flange 12 and the welding torch 3 are electrically insulated by the insulating adapter 13 .

[0028] like Figure 2 and Figure 3 As shown by the dashed line, the second wrist element 11, flange 12, and insulation adapter 13 include a central hole (through hole) 14 extending along the sixth axis G at the radial center of the flange 12. Linear members 50, such as a welding cable, a welding wire 51, a shielding gas line, and a sensor cable 52 connected to the welding sensor 4, are guided along the fourth axis D and passed through the central hole 14.

[0029] The welding gun 3 includes a tubular welding gun body 15, which is disposed at the front end and has an inner hole (not shown), and a neck bracket 16 that supports the base end of the welding gun body 15. The welding gun body 15 includes a power supply chip 17 disposed at the front end. The power supply chip 17 is connected to a welding cable connected to a welding power source (not shown) and has an inner hole (not shown) through which the welding wire 51 is inserted.

[0030] The welding gun body 15 also includes a base end 18 supported by the neck bracket 16, a tip end 19 on which the power supply chip 17 is disposed, and a bent portion 20 disposed between the base end 18 and the tip end 19. The bent portion 20 includes a first bent portion 20a that bends in one direction from the base end 18, a second bent portion 20b that bends in a direction opposite to the first bent portion 20a, and a third bent portion 20c that bends in a direction further opposite to the second bent portion 20b from the second bent portion 20b. The welding gun body 15 is formed by three bends, resulting in a shape in which the base end 18 and the tip end 19 are coaxially arranged in positions aligned with the sixth axis G.

[0031] After passing through the inner bore of the welding gun body 15, the welding wire 51 penetrates the inner bore of the power supply chip 17, thereby protruding from the front end of the welding gun body 15 along the sixth axis G. Furthermore, when passing through the inner bore of the welding gun body 15, the welding wire 51 is bent by the curved portion 20, and is pressed against the inner surface of the inner bore of the power supply chip 17. This ensures stable electrical conduction between the welding wire 51 and the welding cable via the power supply chip 17.

[0032] The neck bracket 16 is equipped with an impact sensor (not shown) that detects contact between the tip of the welding gun body 15 and a peripheral component such as a workpiece.

[0033] The welding gun 3 is fixed to the flange 12 via the insulating adapter 13 by a welding gun bracket 21 .

[0034] The welding gun bracket 21 includes a fixing portion 22 fixed to the insulating adapter 13; a holding portion 23 that holds the base end portion (fixed position) 16a of the neck bracket 16 of the welding gun 3 at a position away from the insulating adapter 13 along the sixth axis G; and a connecting portion 24 that connects the fixing portion 22 and the holding portion 23. In this embodiment, the connecting portion 24 is arranged in a portion of the circumference around the sixth axis G. As a result, a radially inwardly recessed recess 25 is formed between the welding gun 3 and the flange 12 in the region where the connecting portion 24 is not arranged.

[0035] like Figure 3 As shown, welding sensor 4 is located in front of the robot 2's welding gun body 15 in the direction of movement. It scans laser beam L along a scanning plane that intersects the direction of movement and detects the reflected light of laser beam L from the object being welded. This allows the position and condition of the weld joint (weld line; not shown) to be detected before welding. Examples of the weld joint condition include the groove width of a butt weld and the gap of a fillet weld.

[0036] The position and state of the weld joint detected by the welding sensor 4 are fed back to the control device of the robot 2 (not shown), thereby correcting the welding position and welding conditions. This allows high-quality welding even when there are variations in the position and shape of the weld joint.

[0037] In this embodiment, the welding sensor 4 is disposed between the insulating adapter 13 and the fixed position of the welding gun 3 on the welding gun bracket 21, and is fixed to the welding gun bracket 21 by the sensor bracket 26. As a result, the emission surface of the laser beam L and the incident surface of the reflected light of the laser beam L in the welding sensor 4 are disposed closer to the flange 12 than the maximum diameter portion 16a of the neck bracket 16 of the welding gun 3.

[0038] Furthermore, the welding sensor 4 is partially housed in a recess 25 formed between the welding torch 3 and the flange 12 and is positioned at a position and in a direction such that the laser beam L is scanned along a scanning plane parallel to the sixth axis G. Specifically, the welding sensor 4 is positioned so that the emitted laser beam L and the reflected light of the laser beam L returning from the welding object are not blocked by the welding torch 3 and is positioned as close to the sixth axis G as possible.

[0039] Next, the robot system 1 of this embodiment configured as described above will be described.

[0040] According to the robot system 1 of this embodiment, the welding wire 51 is passed through the second wrist element 11, the flange 12, and the central hole 14 of the insulating adapter 13, and is guided into the welding gun 3, which is fixed to the flange 12 via the insulating adapter 13. The welding wire 51 introduced into the welding gun 3 passes through the inner hole of the welding gun body 15 and the inner hole of the power supply chip 17, and protrudes from the front end of the welding gun body 15.

[0041] In this case, according to the present embodiment, by bending the welding gun body 15 of the welding gun 3 three times, the front end of the welding gun body 15 can be positioned on the sixth axis G, and the welding wire 51 can be caused to protrude along the sixth axis G. Since the welding wire 51 is bent while passing through the welding gun body 15, when passing through the inner hole of the power supply chip 17, the welding wire 51 is pressed against the inner surface of the inner hole, thereby generating a stable arc.

[0042] Furthermore, by making the welding wire 51 protrude along the sixth axis G, the scanning plane of the laser beam L can be arranged near the front end of the welding gun 3, and at the same time, the welding sensor 4 is arranged close to the sixth axis G at a position that is significantly retracted from the front end of the welding gun body 15 and close to the flange 12.

[0043] Because welding sensor 4 is significantly set back from the front end of welding gun body 15, there are no other objects around welding gun 3. This reduces interference with surrounding objects around the front end of welding gun body 15 when welding is performed, for example, by inserting welding gun body 15 into a narrow space. Furthermore, positioning welding sensor 4 close to sixth axis G offers the advantage of suppressing radially outward protrusion near flange 12 and preventing interference around wrist unit 9.

[0044] In particular, the welding gun bracket 21 that secures the welding gun 3 to the insulating adapter 13 includes a connecting portion 24 only in a portion of the circumference around the sixth axis G, and a recess 25 is formed in the region without the connecting portion 24. This provides the advantages of being able to accommodate a portion of the welding sensor 4 disposed between the welding gun 3 and the flange 12 within the recess 25, and further reducing the amount of radial outward protrusion of the welding sensor 4 from the sixth axis G.

[0045] Furthermore, by arranging welding sensor 4 near flange 12, sensor bracket 26 for attaching welding sensor 4 can be made small and lightweight. Specifically, if welding sensor 4 is arranged near the tip of welding gun body 15, sensor bracket 26, which is fixed to flange 12 or welding gun bracket 21, becomes longer and heavier.

[0046] When sensor bracket 26 is lengthened, its rigidity decreases, making it more susceptible to vibration and reducing detection accuracy. In contrast, by positioning welding sensor 4 closer to flange 12, sensor bracket 26 fixed to welding gun bracket 21 is shortened, achieving weight reduction. This has the advantage of suppressing vibration even with lower rigidity, enabling high-precision detection of the weld line.

[0047] Furthermore, in this embodiment, by bending the welding gun body 15 three times, the welding wire 51 that protrudes from the center hole 14 of the flange 12 toward the base end 18 of the welding gun body 15 in the direction along the sixth axis G is returned to the sixth axis G at the tip end 19 of the welding gun body 15. This also has the advantage of arranging the tip of the welding wire 51, which is set as the tool tip point serving as the reference for the operation of the robot 2, along the sixth axis G, thereby facilitating teaching and control.

[0048] Furthermore, since welding sensor 4 is disposed significantly back from the front end of welding torch body 15 , welding fume generated at the front end of welding torch body 15 is less likely to reach welding sensor 4 , thereby reducing the occurrence of problems such as contamination of welding sensor 4 .

[0049] In addition, in this embodiment, the welding gun body 15 is bent three times, so that the welding wire 51 is arranged on the sixth axis G at the front end of the welding gun body 15. Figure 4As shown, the welding gun body 15 may be bent twice so that the welding wire 51 projects parallel to the sixth axis G at a distance therefrom. Thus, the welding sensor 4 may be positioned further back toward the flange 12 than the welding gun 3 and closer to the sixth axis G, as in the above-described embodiment.

[0050] In addition, in this embodiment, the sensor bracket 26 is fixed to the welding gun bracket 21 that fixes the welding gun 3 to the flange 12, but instead, the welding gun bracket 21 and the sensor bracket 26 may be fixed to the flange 12 separately. Figures 5 to 7 In the example shown, the welding gun bracket 21 is fixed to a half portion of the periphery of the central hole 14 of the flange 12 , and the sensor bracket 26 is fixed to the remaining half portion.

[0051] By fixing the welding gun bracket 21 and the sensor bracket 26 to the flange 12 , external forces and vibrations applied to the welding gun bracket 21 are prevented from being transmitted to the welding sensor 4 , thereby enabling detection of the weld line with good twisting accuracy.

[0052] In addition, in this embodiment, a vertical articulated robot is used as an example of the robot 2, but the present invention is not limited to this, and any other type of robot may be used.

[0053] In addition, if Figure 8 As shown, the welding gun bracket 21 may also include a first bracket 27 fixed to the flange 12 via the insulating adapter 13, and a second bracket 28 fixed to the welding gun 3. In addition, for example, the first bracket 27 and the second bracket 28 may be positionally adjusted in the direction along the sixth axis G using a long hole 29 provided on one side and a bolt 30 passing through the long hole 29 and detachably fastened to the other side. Figure 8 In the example shown, the first bracket 27 is provided with the long hole 29 and the second bracket 28 is fastened with the bolt 30, but the reverse is also possible.

[0054] In addition, if Figure 8 As shown, the welding sensor 4 can also be mounted relative to the sensor bracket 26 in such a way that the angle can be adjusted around an axis extending in the direction of the scanning plane. Figure 8 In the illustrated example, sensor bracket 26 includes an angle adjustment mechanism formed by an elongated hole 31 extending in an arc about the axis, and a bolt 32 extending through elongated hole 31 and removably fastened to welding sensor 4. By adjusting the mounting angle of welding sensor 4 relative to sensor bracket 26, the position of the scanning plane relative to welding wire 51 can be adjusted.

[0055] Description of the accompanying drawings:

[0056] 1: Robotic system

[0057] 2: Robot

[0058] 3: Welding gun

[0059] 4: Welding sensor

[0060] 9: Wrist unit (wrist mechanism)

[0061] 12: The third wrist element (flange)

[0062] 15: Welding gun body

[0063] 21: Welding gun bracket

[0064] 25: concave part

[0065] 26: Sensor bracket

[0066] 51: welding wire

[0067] G: Sixth axis (rotation axis)

Claims

1. A robot system, characterized in that: have: A robot having a wrist mechanism and a flange at a front end of the wrist mechanism that is rotatable about a rotation axis; a welding gun fixed to the flange by a welding gun bracket; as well as A welding sensor is fixed to the welding gun and detects the welding line welded by the welding gun in advance. The welding sensor is arranged between the flange and the fixed position of the welding gun on the welding gun bracket at a position capable of scanning the laser beam along a plane parallel to the rotation axis in a direction intersecting the welding line. The welding gun includes a tubular welding gun body that is arranged to protrude toward the front end side from the fixed position, and is bent at least twice so that the welding wire protrudes from the front end in a direction parallel to the rotation axis.

2. The robot system according to claim 1, wherein: The welding gun body is bent so that the welding wire protrudes from a front end of the welding gun body along the rotation axis onto the rotation axis.

3. The robot system according to claim 1 or 2, characterized in that: A recessed portion is provided between the flange and the fixing position and is recessed radially inward around the rotation axis. The welding sensor is disposed at a position partially housed in the recess.

4. The robot system according to any one of claims 1 to 3, characterized in that: The welding sensor is fixed to the welding gun bracket.

5. The robot system according to any one of claims 1 to 3, characterized in that: The welding sensor is fixed to the flange using a sensor bracket separately from the welding gun bracket.

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