Electrode replacement device and electrode replacement method

Abstract

The present invention provides an electrode replacement device and electrode replacement method that enable high-speed and high-position-precision replacement of electrodes attached to the torch body of a welding torch. [Solution] The electrode replacement device for replacing the electrode 2 of a welding torch 1 comprises a torch body 4 having a housing chamber 3 capable of housing the electrode of the welding torch, and a drive cylinder 9 that drives a collet chuck 6 capable of chucking and unchucking the electrode. A sub-assembly 10 separable from the torch body 4 includes a nozzle 16 for supplying shielding gas, an electrode 2 inserted into the nozzle, a collet chuck 6, a positioning member 14, and a gas lens 17 as its components. The torch body 4 is equipped with a detachment means 11 that allows the sub-assembly 10, including the positioning member 14, to be attached and detached. Therefore, the electrode can be assembled to the torch body of the welding torch with high positional accuracy.

Description

[Technical Field]

[0001] The present invention relates to an electrode replacement apparatus and an electrode replacement method for a welding torch. [Background Art]

[0002] Conventionally, methods and apparatuses for automating the work of replacing a deteriorated electrode with a new electrode in TIG welding are known. Patent Document 1 discloses an electrode replacement method in which an electrode consumed after repeated welding is pulled out from a welding torch and a new electrode is inserted, wherein the used electrode pulling-out position of a used electrode pulling-out mechanism for pulling out a used electrode from the welding torch and the electrode protruding position of an electrode moving mechanism that moves a new electrode from the electrode supply position of an electrode supply mechanism that supplies a plurality of new electrodes to the electrode protruding position by a driving source are positioned within the operating range of a welding torch moving device, a new electrode is inserted after pulling out the used electrode from the welding torch, and the electrode supply position is positioned outside the operating range of the welding torch moving device, and discloses an automatic TIG welding electrode replacement method. Thereby, the "electrode supply position", the "used electrode pulling-out position" and the "electrode protruding position" are separated by a sufficient distance, and safety is ensured such that a welding operator supplying a new electrode does not get hit or bruised by contacting the robot.

[0003] At the tip portions of the rear collet and the front collet, when in an unclamped state, the electrode can be pulled out by grasping the tip of the electrode by hand and moving it in the tip direction.

[0004] By operating the electrode clamp cylinder, the rear collet body moves toward the tip direction of the welding torch and comes into contact with the expanded diameter tapered portion of the rear collet, and the rear collet body and the rear collet integrally move toward the tip direction of the torch and come into contact with the front collet. Further, the rear collet body, the rear collet, and the front collet integrally move toward the tip direction of the torch, contact the reduced diameter tapered portion of the front collet body, and are pressed thereagainst.

[0005] The force biasing the torch tip is converted into a force acting axially through the tapered structure of the front and rear collets. This force causes the split ends of the front and rear collets to move closer together, clamping the electrode. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2002-307170 [Overview of the project] [Problems that the invention aims to solve]

[0007] However, according to the electrode replacement device described above, the used electrode is removed by hand (paragraph 0030 of Patent Document 1) or by using an electrode removal chuck (paragraph 0047 of Patent Document 1), and a new electrode is attached. Furthermore, when replacing the electrode of a welding torch, the only component that is detached from the torch body is the electrode itself.

[0008] Therefore, if the long electrode is warped, the warping of the electrode is uneven, or the gripping accuracy of the collector chuck that holds the electrode is low, misalignment of the electrode relative to the torch body will occur. Misalignment of the electrode relative to the torch body will result in welding defects.

[0009] The present invention has been made in view of the above-mentioned problems, and provides an electrode replacement device and an electrode replacement method that can replace electrodes attached to the torch body of a welding torch with high positional accuracy and at high speed. [Means for solving the problem]

[0010] The electrode replacement device for a welding torch of the present invention is an electrode replacement device for replacing the electrode (2) of a welding torch (1), A torch body (4) having a housing chamber (3) capable of housing the electrodes of a welding torch, A drive cylinder (9) is attached to the torch body and drives a collet chuck (6) that can chuck and unchuck the electrode, A subassembly (10) comprising a nozzle (16) for supplying shielding gas, an electrode inserted into the nozzle, and a collet chuck, which are separable from the torch body, The torch body is provided with a detachable means (11) that allows the sub-assembly to be attached to and detached.

[0011] According to the electrode replacement device having the above configuration, when removing an electrode from the torch body of a welding torch and attaching a new electrode to the torch body, the subassembly, which consists of the electrode, a collet chuck capable of gripping the electrode, and a nozzle for supplying shielding gas, is made replaceable relative to the torch body. Therefore, the electrode can be assembled to the torch body of the welding torch with high positional accuracy.

[0012] When replacing electrodes, the sub-assembly can be separated from the torch body, and the new sub-assembly can be assembled to the torch body quickly and reliably. The electrode replacement method for a welding torch according to the present invention is: A step of removing a subassembly (10) from the torch body (4), which includes an electrode (2), a collet chuck (6) capable of chucking and unchucking the electrode, and a nozzle (16) as its components, The process involves inserting a new sub-assembly into the torch body, The process includes the step of positioning the positioning member of the new sub-assembly relative to the torch body.

[0013] According to the electrode replacement method described above, a sub-assembly is formed, consisting of a collet chuck, electrode, and nozzle. This sub-assembly can be assembled to the torch body of the welding torch with high positional accuracy. When replacing an electrode, when the sub-assembly is quickly separated from the torch body and a new sub-assembly is assembled to the torch body, the separation and assembly can be performed quickly and reliably with high positional accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] [Figure 1] Partial sectional view of a welding torch according to an embodiment of the present invention. [Figure 2] Enlarged view of section II in FIG. 1. [Figure 3] Sectional view of the tip of a welding torch showing a state where an electrode is separated from the welding torch according to an embodiment of the present invention. [Figure 4] Sectional view of the tip of a welding torch showing a state where an electrode is attached to the welding torch according to an embodiment of the present invention. [Figure 5] An enlarged sectional view of section V in FIG. 4 for explaining the problem of the present invention. [Figure 6] Graph for explaining the problem of the present invention. [Figure 7] Process diagram showing the electrode replacement process according to an embodiment of the present invention. [Figure 8] Partial sectional view of the tip of a welding torch according to a comparative example. MODE FOR CARRYING OUT THE INVENTION

[0015] Hereinafter, an electrode replacement method and an electrode replacement apparatus according to embodiments of the present invention will be described with reference to the drawings. In a plurality of embodiments, substantially identical components are denoted by the same reference numerals, and descriptions thereof are omitted.

[0016] (One Embodiment) One embodiment of the present invention will be described with reference to FIGS. 1 to 7. FIG. 1 shows a partial sectional view of an embodiment of a TIG welding torch to which the electrode replacement apparatus of the present invention is applied.

[0017] As shown in FIG. 1, the welding torch 1 includes a collet chuck 6 that chucks and unchucks the electrode 2, and a drive cylinder 9 that drives the collet chuck 6. The collet chuck 6, which is installed inside the torch body 4 of the welding torch 1, is movable vertically by the operation of the drive cylinder 9, and is capable of gripping and releasing the electrode 2.

[0018] The collet chuck 6 is fitted to the inner circumferential surface of the positioning member 14, which will be described later, and its tip is tapered in diameter. The collet chuck 6 has a split end and an inner diameter large enough to insert or remove the electrode 2. When the collet chuck 6 moves downward, the split ends move closer together, reducing the inner diameter of the collet chuck 6 and chucking the electrode 2.

[0019] The subassembly 10, which is separable from the torch body 4, includes an electrode 2, a collet chuck 6 for chucking and unchucking the electrode 2, a positioning member 14 for improving the positioning accuracy of the electrode relative to the torch body 4, a gas lens 17 for rectifying the shielding gas, and a nozzle 16 for supplying the shielding gas.

[0020] The detachable means 11 for attaching and detaching the sub-assembly 10 to the torch body 4 includes a compression coil spring 22 equivalent to a spring, a spring seat 23, a ball 20 for holding the nozzle, a ball case 21, and a clamping mechanism 11. The clamping mechanism 11 includes a positioning member 14 attached to the sub-assembly 10.

[0021] The positioning member 14 is separable from the torch body 4 and has a basic cylindrical shape, with a large diameter portion 141, a flange portion 143, and a small diameter portion 142 located axially midway between the large diameter portion and the flange portion. The positioning member 14 is capable of accommodating an electrode 2 and a collet chuck 6 that can chuck and unchuck the electrode 2 in the axial direction inside.

[0022] The clamping mechanism 11 houses one ball 20 in each of a plurality of ball housing chambers 211 that are radially formed in a ball case 21 fixed to the torch body 4. The ball case 21 has an axis that is coaxial with the axis of the torch body 4. Three ball housing chambers 211 are formed radially on a virtual cross-section from the central axis of the ball case at equal intervals, for example, at 120-degree intervals, and one ball 20 is housed in each ball housing chamber 211 in a radially free state.

[0023] A compression coil spring 22, which corresponds to a spring located radially outward of the ball case 21, has one end 221 locked to the end of the torch body 4, and the other end 222 locked to a spring seat 23 that is axially slidable on the ball case 21 on the radially outward side of the ball case 21. As shown in Figure 3, the spring seat 23 is in an unclamped state when raised, and as shown in Figure 4, the spring seat 23 is in a clamped state when lowered.

[0024] In the state shown in Figure 5 when the sub-assembly 10 described later is assembled, the ball 20 is fitted into the small-diameter portion 142 of the positioning member 14, defining the position of the positioning member 14 relative to the torch body 4. In the state shown in Figure 3, the ball 20 is in a radially outward position than the ball position shown in Figure 5 due to the release (unlocking) of the ball housing chamber 211 by the spring seat 23, and the fitting of the small-diameter portion 142 of the positioning member 14 is released.

[0025] As shown in Figure 5, the positioning member 14 has a large-diameter portion 141 at its upper end. The upper surface of the outer wall of the large-diameter portion 141 is fitted into the inner wall 212 of the recess of the ball case 21, which is integrated with the torch body 4. The positioning member 14 and the ball case 21 are configured to minimize the radial displacement a of the large-diameter portion 141, as shown by arrow a in Figure 5, and the displacement b due to the perpendicularity (angle of inclination) θ between the large-diameter portion 141 and the flange portion 143. The effects of this configuration will be discussed later with data comparison results.

[0026] The equipment components include a U-shaped pressing member 41 that pushes the spring seat 23 upward against the compression coil spring 22, a nozzle chuck 43 (see Figure 7) capable of gripping the outer wall of the holder 15 integrated with the nozzle 16, a pallet (not shown) for collecting the old electrode, a pallet 42 for mounting the new electrode, a driving means 45 (see Figure 3) for driving the U-shaped pressing member 41, and a driving means 46 (see Figure 7) for driving the nozzle chuck 43. The pressing member 41 can switch the clamping mechanism 11 between clamping and unclamping. The nozzle chuck 43 can chuck and uncuck the holder 15, and can pull out the chucked sub-assembly 10 from the torch body 4. The pallet 42 for transporting the new electrode can insert the sub-assembly 10 into the torch body 4. After inserting the electrode 20 of the sub-assembly 10 into the torch body 4, the pressing member 41 is lowered (separated) from the spring seat 23, and the ball 20 is fitted into the small diameter portion 142 of the positioning member 14 and clamped.

[0027] When replacing a worn electrode with a new one, the sub-assembly 10 containing the old electrode is withdrawn from the torch body 4, and the sub-assembly 10 containing the new electrode 2, which is transported from the pallet 42, is assembled into the torch body 4.

[0028] The operation for removing the old electrode and assembling the new electrode will be explained based on Figure 7. The operation proceeds in the order shown in Figures 7A to 7E, replacing the sub-assembly 10 (electrode 2, collet chuck 6, nozzle 16, gas lens 17, etc.).

[0029] As shown in Figure 7A, in the initial position, the pressing member 41 is in a lower position, separated from the spring seat 23, and the nozzle chuck 43 chucks the nozzle holder 15 in the directions of arrows 25 and 26. Next, the pressing member 41 at the position shown in Figure 7A is raised, pressing the spring seat 23 in the direction of arrow 27 against the compression coil spring 22, and unclamping the nozzle 16 as shown in Figure 7B.

[0030] Next, the nozzle chuck 43 is lowered in the direction of arrow 28 from the position shown in Figure 7B. At this time, the ball 20 moves from the fitted state of the small diameter portion 142 over the large diameter portion 141, the nozzle chuck 43 pulls the sub-assembly 10 out of the torch body 4, and separates the sub-assembly 10 from the torch body 4 to the position shown in Figure 7C.

[0031] Next, a pallet 42 with a new electrode placed on it moves below the torch body 4, which is in the electrode-removed state, and the electrode 2, collet chuck 6, and positioning member 14 of the new sub-assembly 10 are inserted from below the torch body 4. At this time, the ball 20 in the ball housing chamber 211 of the ball case 21, which is integrated with the torch body 4, moves over the large diameter portion 141 of the positioning member 14 and faces the small diameter portion 142. Figure 7D shows the state after the new sub-assembly 10 has been inserted.

[0032] When the pressing member 41 is lowered in the direction of arrow 29 from the state shown in Figure 7D, the extension force of the compression coil spring 22 causes the spring seat 23 to press the ball 20 in the radial direction, fitting the ball 20 into the small diameter portion 142, and clamping the sub-assembly 10 (nozzle 16) to the position shown in Figure 7E.

[0033] According to this embodiment, when replacing electrodes, the removal and installation of the sub-assembly 10, which consists of the collet chuck 6, nozzle 16, electrode 2, positioning member 14, and gas lens 17, is performed automatically.

[0034] As shown in Figure 5, the positioning member 14, which is used as one of the components of the subassembly, has a large-diameter portion 141 at the upper end on the side that is inserted into the torch body 4. The upper surface of the outer wall of the large-diameter portion 141 abuts against and fits with the inner wall 212 of the recess of the ball case 21, which is integrated with the torch body 4. The flange portion 143 abuts against the stepped portion 213 of the ball case 21.

[0035] With this configuration, the radial displacement a of the large-diameter portion 141 of the positioning member 14, as shown by arrow 30 in Figure 5, and the displacement b due to the perpendicularity (angle of inclination) θ between the large-diameter portion 141 and the flange portion 143 can be suppressed to a small amount.

[0036] (Explanation of comparative forms) This embodiment will be described in comparison with a comparative embodiment. Figure 8 shows the tip of the TIG welding torch of the comparative embodiment used for comparison. The connecting member 54, which is fixed to the nozzle 52, is screw-connected to the torch body 51. This screw connection was previously made manually. Replacing the electrode in the welding torch involved raising (releasing) the collet chuck 6, pulling out only the used electrode 2, inserting the new electrode 2, lowering the collet chuck 6, and clamping it. The setup time for this electrode replacement operation was as follows:

[0037] The results of the comparative setup time test showed that, according to the experimental data, in the comparative configuration, the setup time loss for electrode replacement accounted for 12.9% of the total replacement time, whereas in the above embodiment, the setup time loss for electrode replacement was reduced to 2.8% of the total replacement time. The results of a comparative test of electrode replacement time showed that in the comparative configuration, the time required for electrode replacement was 5 minutes, while in the above embodiment, the time required for electrode replacement was reduced to 6 seconds.

[0038] Next, an experiment was conducted to investigate the range of electrode tip misalignment that causes welding defects in the welding torch with replaced electrodes, based on the above embodiment. The results of that experiment are shown below. The following explanation will be given with reference to Figures 5 and 6. Figure 5 shows the configuration features of one embodiment of the present invention. Figure 6 shows the range of electrode tip misalignment that causes welding defects, with the regions in the figure representing the allowable range of welding and the measured values. For welding defects with an inner diameter tolerance of 0 to -0.01 (mm) and an outer diameter tolerance of 0.018 to 0 (mm), the measured misalignment a was 0.028 (mm), and for perpendicularity of 0.01 (mm), the measured misalignment b was 0.006 (mm), resulting in a + b = 0.034 (mm).

[0039] The welding tolerance range is as shown in Figure 6, with the vertical axis x and horizontal axis y, where the allowable displacement is x < 0.2 (mm) and the allowable y < 0.2 (mm), and the sum of the allowable displacements was a + b = 0.034 < 0.2. Therefore, according to the above embodiment, it was found that the range of electrode tip misalignment when the sub-assembly is replaced is within the allowable range for welding. Furthermore, according to this embodiment, by devising a detachment mechanism, which is one of the components on the welding torch side, and providing a pressing member and a nozzle chuck on the operating mechanism or driving mechanism on the equipment side that operates this detachment mechanism, and by configuring the system to automatically operate the pressing member and nozzle chuck, the electrodes of the welding torch can be replaced at high speed.

[0040] (Other embodiments) This invention can also be applied to electrode replacement devices for welding torches other than TIG welding torches. The collet may be split in two, four, or in any other form. In the above embodiment, an embodiment was described in which the collet and the electrode are replaced simultaneously.

[0041] The locking mechanism for locking the nozzle to the torch body in the subassembly of the present invention is not limited to having the push-lock mechanism described in the embodiments above, but may also be a rotary locking mechanism, a cam-type locking mechanism, or other mechanisms.

[0042] The small-diameter portion of the positioning member that locks or clamps by ball fitting may be cylindrical, or it may be a small hole, small recess, etc., into which the ball can be fitted. The number of ball housing chambers formed in the ball case is not limited.

[0043] The form of the clamping mechanism may be other than the form shown in the above embodiment, for example, a form that does not use a ball. Here, a clamping mechanism refers to a mechanism that clamps and fixes an object.

[0044] In the above embodiment, a detachable means 11 was used to attach and detach the sub-assembly 10 to the torch body 4. However, the present invention may also include a detachable means other than the clamp mechanism shown in the above embodiment.

[0045] The components of the subassembly of the present invention may selectively include the components described in the above embodiments, as long as they include electrodes and nozzles, or they may include components other than those described above.

[0046] According to the present invention, the attachment / detachment means may be a clamping mechanism (11) that can clamp and unclam the subassembly to the torch body. The clamping mechanism may have a positioning member (14) in the subassembly that can position the replaced electrode relative to the torch body.

[0047] The positioning member may have a basic cylindrical shape and include a large-diameter portion (141), a flange portion (143), and a small-diameter portion (142) between the large-diameter portion and the flange portion. This improves the positional accuracy of the electrode relative to the torch body, thereby providing an electrode replacement device that is less likely to cause welding defects.

[0048] The clamping mechanism may have a ball (20) for positioning the positioning member relative to the torch body, a ball case (21) having a ball housing chamber (211) for housing the ball, a spring (22) for biasing the ball in the clamping direction, and a spring seat (23) on the torch body side that receives the biasing force of the spring.

[0049] The attachment / detachment means may be provided on the equipment (40) side with a pressing member (41) that, when the spring seat is pressed against the spring, releases the engagement between the ball and the positioning member and switches to an unclamped state. The attachment / detachment means may be provided on the equipment (40) side with a nozzle chuck (43) that grips the nozzle on the assembly side and pulls out the sub-assembly relative to the torch body. The attachment / detachment means may include a pallet (42) on the equipment side for transporting the newly attached sub-assembly to the torch body from which the sub-assembly has been removed. According to the present invention, a detachable sub-assembly can be securely attached to the torch body of a welding torch by operating a detachable means.

[0050] As stated above, the present invention is not limited to the embodiments described above, and can be implemented in various forms without departing from its essence. [Explanation of Symbols]

[0051] 1. Welding torch, 2 electrodes, 4 Torch bodies, 6 collet chucks, 9 drive cylinder, 10 subassemblies, 11 Detachable means (clamping mechanism), 14 Positioning member, 15 holders, 16 nozzles, 20 balls, 22 Compression coil springs, 40 equipment; 41. Pressing member.

Claims

1. An electrode replacement device for replacing the electrode (2) of a welding torch (1), A torch body (4) having a housing chamber (3) capable of housing the electrodes of a welding torch, A drive cylinder (9) is attached to the torch body and drives a collet chuck (6) that can chuck and unchuck the electrode, A subassembly (10) comprising a nozzle (16) for supplying shielding gas, which is separable from the torch body, the electrode inserted into the nozzle, and the collet chuck, An electrode replacement device comprising a torch body and a detachable means (11) for attaching and detaching the sub-assembly.

2. The electrode replacement device according to claim 1, wherein the attachment / detachment means is a clamping mechanism (11) capable of clamping and unclamping the sub-assembly with respect to the torch body.

3. The electrode replacement device according to claim 2, wherein the clamping mechanism has a positioning member (14) in the subassembly that can position the replaced electrode relative to the torch body.

4. The electrode replacement device according to claim 3, wherein the positioning member has a basic cylindrical shape and comprises a large diameter portion (141), a flange portion (143), and a small diameter portion (142) between the large diameter portion and the flange portion.

5. The electrode replacement device according to claim 3, wherein the clamping mechanism has a ball (20) for positioning the positioning member relative to the torch body, a ball case (21) having a ball housing chamber (211) for housing the ball, a spring (22) for biasing the ball in the clamping direction, and a spring seat (23) on the torch body side that receives the biasing force of the spring.

6. The electrode replacement device according to claim 5, wherein the attachment / detachment means is provided on the equipment (40) side with a pressing member (41) that, when the spring seat is pressed against the spring, releases the engagement between the ball and the positioning member and switches to an unclamped state.

7. The electrode replacement device according to claim 1 or 2, wherein the attachment / detachment means is provided on the equipment (40) side with a nozzle chuck (43) that grips the nozzle on the sub-assembly side with respect to the torch body and pulls out the sub-assembly.

8. The electrode replacement device according to claim 1 or 2, wherein the attachment / detachment means is provided on the equipment side with a pallet (42) for transporting a newly attached sub-assembly to the torch body from which the sub-assembly has been removed.

9. A method for replacing the electrode of a welding torch, A step of removing a subassembly (10) from the torch body (4), which includes an electrode (2), a collet chuck (6) capable of chucking and unchucking the electrode, and a nozzle (16) as its components, The process involves inserting a new sub-assembly into the torch body, A method for replacing the electrode of a welding torch, comprising the step of positioning the positioning member of the new sub-assembly with respect to the torch body.

10. Instead of the step of positioning the new sub-assembly relative to the torch body, A method for replacing the electrode of a welding torch according to claim 9, further comprising the step of bringing the upper end of the positioning member of the new sub-assembly into contact with the inner wall (212) of the recess of the ball case of the torch body.

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