Polishing device for welding electrode

Abstract

To perform polishing on a welding electrode by stabilizing the posture during polishing and thereby enable continuous high-quality welding.SOLUTION: A polishing device 10 comprises a polishing blade 13 capable of polishing a tip of a welding electrode 1, a holder 14 that holds the polishing blade 13 and is rotatable about an axis, and a guide member 16 that is arranged coaxially with a rotation axis X of the holder 14 and is capable of supporting the welding electrode 1 in an inserted state.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a welding electrode grinding device. [Background technology]

[0002] As is well known, resistance welding, typified by spot welding, is performed by passing a large current through one or more electrodes pressed against the workpiece. Repeated welding of this type can cause the electrode surface to deform or become coated with plating components from the steel sheet being welded. Therefore, the tip of the electrode is periodically polished to restore the electrode surface to its original condition.

[0003] The above-mentioned polishing process is performed by, for example, pressing a pair of electrodes attached to the tip of the arm of the welding gun against a cutter holder to which a cutter (polishing blade) is attached, clamping the electrodes, and then rotating the cutter holder around its axis (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2018-167303 Summary of the Invention [Problem to be solved by the invention]

[0005] Spot welding can be performed in two ways: one in which a pair of electrodes facing each other sandwiches a welding target (such as overlapping steel plates), and another in which only one electrode is pressed against the welding target (also known as indirect welding or one-sided welding). As described in Patent Document 1, this is not a significant problem when grinding is performed with a pair of electrodes sandwiching a cutter holder. However, in the case of an electrode for one-sided welding, grinding is performed with a single electrode attached to the tip of the arm of a welding gun pressed against the cutter of the cutter holder from only one side. Therefore, when the electrode is pressed against the cutter, the reaction force that the electrode receives from the cutter holder may cause significant deformation (such as deflection) of the arm of the welding gun. If the electrode is pressed against the cutter with a deformed arm, the position or posture of the electrode may become unstable, and grinding by the cutter may occur with the electrode swinging. Alternatively, the electrode may be pressed against the cutter at an angle relative to the rotation axis of the cutter (cutter holder), resulting in uneven grinding. In either case, the electrode tip will not be sufficiently polished, resulting in an unstable surface condition, which may adversely affect the quality of subsequent welding.

[0006] In view of the above circumstances, the technical problem to be solved in this specification is to perform grinding on a welding electrode while stabilizing the posture during grinding, thereby enabling continuous high-quality welding. [Means for solving the problem]

[0007] The above-mentioned problems are solved by the welding electrode sharpening device according to the present invention, which comprises a sharpening blade capable of sharpening the tip of a welding electrode, and a holder that holds the sharpening blade and is rotatable about its axis, and further comprises a guide member that is arranged coaxially with the rotation axis of the holder and that can support the welding electrode in an inserted state.

[0008] In the grinding device according to the present invention, a guide member capable of supporting the inserted welding electrode is disposed coaxially with the rotation axis of the grinding blade holder. By providing this guide member, when the welding electrode is introduced toward the grinding blade, the welding electrode is pressed against the grinding blade while supported by the guide member. This stabilizes the position of the welding electrode when pressed against the grinding blade, thereby enabling stable grinding without bias or variation.

[0009] In addition, in the grinding device according to the present invention, the guide member may be composed of a plurality of rolling elements capable of supporting the outer surface of the welding electrode inserted into its inner circumference, and a holding member that holds the plurality of rolling elements rotatably.

[0010] The guide member can have any shape as long as it allows the welding electrode to move axially smoothly and in a stable position. On the other hand, when a welding electrode is ground using the above-described rotary grinding blade, protrusions called burrs may form around the welding electrode during the grinding process. Therefore, if the guide member is configured, for example, as a plain bearing, in consideration of the electrode shape and movement direction, the axial movement of the welding electrode may cause the protrusions to get caught on the plain bearing, hindering smooth movement. In contrast, by configuring the guide member with multiple rolling elements capable of supporting the outer circumferential surface of the welding electrode and a holding member that rotatably holds these multiple rolling elements, the welding electrode can be supported in point contact or in a state close to point contact. This reduces the possibility of the protrusions around the welding electrode interfering with the rolling bearing (rolling elements). Even if the rolling elements interfere with the protrusions, the rolling elements roll as the welding electrode moves, allowing the welding electrode to move smoothly.

[0011] Furthermore, in the grinding device according to the present invention, the guide members may be arranged at a plurality of positions spaced apart from one another in the axial direction, and each guide member may be configured to be able to support either the electrode tip located at the most distal end of the welding electrode or the shank portion to which the electrode tip can be attached.

[0012] In this way, by arranging the guide members at multiple positions spaced apart in the axial direction and configuring each guide member to support either the electrode tip or the shank, the welding electrode can be supported over as long a span as possible in the axial direction. This can be extremely effective in preventing the welding electrode from tilting. Furthermore, for example, by configuring one of the two guide members to support the electrode tip and the other to support the shank, the welding electrode can be supported over as long a span as possible in the axial direction. [Effects of the Invention]

[0013] As described above, the welding electrode grinding device according to the present invention makes it possible to grind the welding electrode while stabilizing its posture during grinding, thereby enabling high-quality welding to be continued. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a front view showing the overall configuration of a welding electrode grinding device according to an embodiment of the present invention; [Figure 2] FIG. 2 is a front view of a main part of the polishing apparatus shown in FIG. [Figure 3] 3 is a view of the holder shown in FIG. 2 as viewed in a direction along the rotation axis. [Figure 4] 3 is a view of the guide member shown in FIG. 2 as viewed in a direction along the rotation axis of the holder. [Figure 5] 2 is a front view of a main part of a welding gun to which a welding electrode to be ground by the grinding device shown in FIG. 1 is attached. [Figure 6] 2 is an enlarged front view of a main part showing an example of a usage mode of the grinding device shown in FIG. 1, in which a welding electrode is inserted into a guide member. FIG. [Figure 7] FIG. 10 is a front view of a main part of a welding electrode grinding device according to another embodiment of the present invention. [Figure 8] 10 is a view showing a guide member of a welding electrode grinding device according to another embodiment of the present invention, viewed from a direction along the rotation axis of the holder. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0015] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A welding electrode grinding device according to an embodiment of the present invention will now be described with reference to the accompanying drawings.

[0016] 1 shows a front view of a welding electrode grinding device 10 according to one embodiment of the present invention. This grinding device 10 is capable of grinding the tip of a welding electrode 1 (see FIG. 5) used, for example, in spot welding, and includes a base 11 fixed to the ground, a support 12 extending laterally from the base 11, a holder 14 for a grinding blade 13 attached to the support 12, a drive unit 15 that rotates and drives the holder 14, and a guide member 16.

[0017] Although not shown, for example, an elastic member such as a spring may be interposed between the base 11 and the support 12, so that the entire support 12 is supported in the vertical direction relative to the base 11. Similarly, although not shown, a reducer may be interposed between the holder 14 and the drive unit 15, so that the rotation speed of the holder 14 can be adjusted.

[0018] As shown in FIG. 2, the holder 14 is provided with a pair of recesses 17, 17 that open upward and downward, respectively. A grinding blade 13, 13 is attached to each recess 17, 17. In this case, the opening direction of each recess 17, 17 coincides with the direction along the rotation axis (rotation axis) X of the holder 14. Each recess 17, 17 is formed with a shape and size that allows the tip of the welding electrode 1 to be ground to be inserted therein. By inserting the welding electrode 1 along the rotation axis X and pressing its tip against the surface of the recess 17, grinding processing can be performed with the grinding blade 13 rotated around the rotation axis X. In this illustrated example, a cylindrical portion with a constant inner diameter is provided continuously at the open end of each recess 17 (see FIG. 2).

[0019] Each grinding blade 13 is made of, for example, cemented carbide. Each grinding blade 13 has an arc-shaped concave surface 13a on both the top and bottom sides thereof, which corresponds to the tip shape of the welding electrode 1, and corners on the edges of the concave surfaces 13a form cutting edges 13b that cut the welding electrode 1. In this embodiment, two grinding blades 13 are disposed at two locations in the circumferential direction, with their phases shifted by 180° (see FIG. 3). Although not shown, only one grinding blade 13 may be disposed in each recess 17, or three or more grinding blades 13 may be disposed in three or more locations in the circumferential direction of each recess 17.

[0020] The guide member 16 is configured to allow the welding electrode 1 to be inserted into its inner periphery and is arranged coaxially with the rotation axis X of the holder 14 (see FIGS. 1 and 2). In this embodiment, as shown in FIG. 4, the guide member 16 is composed of a plurality of rolling elements 18 arranged at a plurality of positions along the circumferential direction and a holding member 19 that rotatably holds the plurality of rolling elements 18. In this illustrated example, all of the rolling elements 18 are spherical and have the same outer diameter. Furthermore, each rolling element 18 is configured to be able to roll in all directions. In this case, all of the rolling elements 18 are arranged at the same radial position of the cylindrical holding member 19 so that they have the same inscribed circle radius. In this case, the radius of an imaginary circle inscribed with each rolling element 18 (the inscribed circle radius) is set to an appropriate size depending on the outer diameter of the welding electrode 1 to be inserted into the inner periphery of the guide member 16. That is, it is preferable to appropriately set the outer diameter dimension of each rolling element 18 and its radial position relative to the holding member 19 so that the welding electrode 1 can be supported at a position and posture where its central axis coincides with the rotation axis X of the holder 14, and the welding electrode 1 can be moved smoothly in the direction along the rotation axis X.

[0021] In this embodiment, the guide members 16 having the above configuration are disposed at a plurality of positions spaced apart from one another in the axial direction. In the illustrated example, two guide members 16 are disposed at two positions spaced apart from one another in the axial direction. Specifically, one guide member 16 located relatively lower (closer to the grinding blade 13) can support the electrode tip 2 located at the most distal end of the welding electrode 1, and the other guide member 16 located relatively higher can support the shank portion 3 located closer to the base end of the welding electrode 1 than the electrode tip 2. These two guide members 16 are fixed to the support body 12 via fixing members 20 (see FIG. 2 ). Therefore, by appropriately setting the attachment positions of each guide member 16 relative to the fixing members 20, the support surfaces of each guide member 16 (here, the inner surfaces of each rolling element 18) can be set at predetermined positions.

[0022] An example of how the polishing apparatus 10 according to this embodiment is used will now be described together with its effects.

[0023] First, the grinding device 10 having the above configuration is installed within the movement range of a welding robot (not shown). Then, with the holder 14 rotated about the rotation axis X by the drive unit 15, the welding robot (not shown) is driven to insert the welding electrode 1 of the welding gun 4 (see FIG. 5) attached to the tip of the arm of the welding robot toward the corresponding recess 17 of the holder 14. That is, as shown in FIG. 4, in the case where the welding gun 4 has welding electrodes 1, 1 for one-sided welding attached to both the top and bottom of the tip of the arm, and the welding electrode 1 to be ground is facing downward, the lower welding electrode 1 is moved above the upper holder 14 and then lowered, thereby inserting the tip of the welding electrode 1 into the recess 17 of the upper holder 14.

[0024] At this time, a guide member 16 is disposed above the upper holder 14 and is coaxial with the rotation axis X of the holder 14 (see FIG. 2). Therefore, when the tip of the welding electrode 1 is lowered toward the recess 17 of the upper holder 14, the outer periphery of the welding electrode 1 is supported by the guide member 16 before the tip of the welding electrode 1 abuts against the surface of the recess 17 (see FIG. 6). Therefore, the welding electrode 1 inserted into the inner periphery of the guide member 16 is inserted into the recess 17 in a position and orientation where its central axis coincides with the rotation axis X, and is pressed against the surface. At this time, because the holder 14 is rotating about the rotation axis X, the surface of the electrode tip 2, which forms the tip end of the welding electrode 1, is cut by the cutting edge 13b of the grinding blade 13 and ground (shaped) into a predetermined shape.

[0025] At this time, welding electrode 1 is guided into recess 17 while being supported by guide member 16 in the position and posture described above, so even if a reaction force acts on welding electrode 1 when it is pressed against the surface of recess 17, the reaction force is received by guide member 16. This makes it possible to prevent deformation such as bending of arm 5 of welding gun 4 as much as possible, thereby making it possible to perform grinding on the tip of welding electrode 1 in a stable position and posture with reduced vibration. This makes it possible to perform high-quality, even grinding.

[0026] In particular, as in this embodiment, by arranging multiple guide members 16 at multiple positions spaced apart from one another in the axial direction and allowing the welding electrode 1 to be supported by multiple guide members 16, the welding electrode 1 can be supported over as long a span as possible in the axial direction. This makes it possible to more effectively suppress tilting of the welding electrode 1.

[0027] In addition to the above-mentioned effects, as an additional effect, vibration during grinding is suppressed by suppressing the wobble of the welding electrode 1 during grinding, which is expected to improve the lifespan of the grinding blade 13, and since the rotation of the rotational driving force transmission system (gears, etc.) to the drive unit 15 and holder 14 is expected to be stabilized, pulsation (torque fluctuations) can be suppressed, thereby making it possible to save energy.

[0028] Furthermore, when performing the grinding work on the welding electrode 1 attached to this type of welding robot, the welding robot is taught the grinding work in advance, and even in this case, the insertion of the welding electrode 1 into the recess 17 of the holder 14 is guided (supported) by the guide member 16, so that it is expected that the number of teaching steps will be reduced.

[0029] Although one embodiment of the present invention has been described above, the welding electrode grinding device according to the present invention can also have other configurations than those described above without departing from the spirit of the invention.

[0030] For example, in the above embodiment, the guide member 16 is exemplified as having a plurality of rolling elements 18 arranged along the circumferential direction. However, this is not limiting. FIG. 7 shows a front view of a guide member 26 according to one example (another embodiment of the present invention). As shown in FIG. 7, the guide member 26 according to this embodiment has a plurality of rolling elements 18. It is the same as the embodiment shown in FIG. 1 in that it is capable of supporting (guiding) the welding electrode 1 with these rolling elements 18. However, it differs in the arrangement of the rolling elements 18. That is, in the guide member 26 according to this embodiment, the plurality of rolling elements 18 are arranged in the guiding direction, i.e., along the central axis of the guide member 26 (coincident with the rotation axis X). In this case, it is preferable that multiple rows of rolling elements 18 are arranged at multiple positions around the circumferential direction of the guide member 26. In this case, all of the rolling elements 18 arranged in the axial and circumferential directions are held by a single common holding member 27.

[0031] According to the guide member 26 having the above configuration, the welding electrode 1 (electrode tip 2 and shank portion 3) can be guided toward the recess 17 while being supported over a predetermined axial span, so that only one guide member 26 (holding member 27) is required and tilting of the welding electrode 1 can be more effectively prevented.

[0032] Alternatively, in the above two embodiments, the guide members 16, 26 are illustrated as being configured so that a plurality of spherical rolling elements 18 can support the welding electrode 1, but other configurations are of course possible. Fig. 8 shows a plan view (viewed from the direction along the rotation axis X) of a guide member 36 according to one such example (another embodiment of the present invention). This guide member 36 has a plurality of rollers 37 as rolling elements and a holding member 38 that holds the rollers 37 so that they can roll freely.

[0033] In this way, even if the rolling elements (rollers 37) have a shape other than a sphere, by appropriately setting the arrangement of the rollers 37, the welding electrode 1 (electrode tip 2 and shank portion 3) can be supported over a predetermined axial span and guided toward the recess 17, thereby making it possible to effectively prevent the welding electrode 1 from tilting.

[0034] In the above description, guide members 16, 26, 36 have been described as having a plurality of rolling elements 18 (rollers 37), but the present invention is not limited to this. For example, the guide members may take any form, such as a sliding bearing, as long as they have a structure that can support welding electrode 1 in an inserted state (that can guide welding electrode 1 toward recess 17 in a supported state). [Explanation of symbols]

[0035] 1 welding electrode 2-electrode chip 3 Shank 4 welding guns 5 Arm section 10 Polishing equipment 11 Base 12 Support 13 Polishing blade 13a concave 13b Blade part 14 Holder 15 Drive unit 16, 26, 36 Guide members 17 Recess 18 Rolling elements 19, 27, 38 Retaining member 20 Fixing member 37 Laura X rotation axis

Claims

[Claim 1] A welding electrode sharpening device including a sharpening blade capable of sharpening the tip of a welding electrode and a holder that holds the sharpening blade and is rotatable about its axis, a guide member arranged coaxially with the rotation axis of the holder and capable of supporting the welding electrode in an inserted state;

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