Contact tip reshaping device

Abstract

A contact tip reshaping device 3 comprises: a core rod 37 having a circular cross-section; and three or more pressing metal pieces 36 disposed so as to be arranged in the circumferential direction along an outer circumferential surface 23c of a contact tip 23. Each pressing metal piece 36 has an arc-shaped shaping surface 36a. A shaping unit 30 includes: a guide part 31b for guiding each pressing metal piece 36 in the radial direction of the contact tip 23; and a shaping part 30 for causing the plurality of pressing metal pieces 36 to advance / retreat in the guidance direction of the guide part 31b. Shaping loads from the plurality of pressing metal pieces 36 are simultaneously applied to the outer circumferential surface 23c of the contact tip 23.

Description

Contact tip reshaping device

[0001] The present invention relates to an apparatus for reshaping contact tips for arc welding.

[0002] Conventionally, automated arc welding has been performed using a robot holding a welding torch, for example, on welding lines for automotive parts. The welding wire used in arc welding is fed to the workpiece through a guide hole formed in the contact tip. However, over a long period of use, the inner surface of the guide hole wears due to friction with the welding wire, causing the hole diameter to expand or the cross-sectional shape to become non-circular. As a result, poor power supply occurs and the welding wire curl cannot be corrected, resulting in the inability to achieve high-quality welding.

[0003] Therefore, contact tips are remolded. Contact tip remolding devices used to remolde contact tips are known, for example, from Patent Documents 1 to 3. The contact tip remolding device disclosed in Patent Document 1 includes a mold disposed to face the tip side of the contact tip. The mold is provided with a plastically processed hole formed at a position corresponding to the contact tip, the diameter of which decreases with increasing distance from the tip side of the contact tip. The inner peripheral surface of the plastically processed hole is provided with three protrusions that protrude inward of the plastically processed hole, extend along the center line of the plastically processed hole, and are equally spaced circumferentially about the hole center line. By lowering the mold, these protrusions are pressed against the outer peripheral surface of the contact tip, thereby performing a remolding process in which the expanded guide hole diameter of the contact tip is reduced to its original guide hole diameter.

[0004] In Patent Document 2, the outer periphery of the electrode tip is pressed from both radial sides to correct the inner diameter of the electrode wire through-hole.

[0005] Patent Document 3 discloses a contact tip remolding tool including a chuck body fixed to a lower die plate and having a tapered contact surface, and a chuck fastener fixed to an upper die plate and having a tapered hole. In Patent Document 3, the chuck body is lowered relative to the chuck fastener by a press or the like, thereby pressing the outer peripheral surface of the peripheral wall of the contact tip radially inward and reducing the diameter of the guide hole.

[0006] Japanese Patent No. 7130283 Japanese Patent Application Laid-Open No. 2006-167733 Japanese Patent Application Laid-Open No. 2001-246472

[0007] According to Patent Document 1, the reshaped contact tip is formed in such a manner that the regions on the tip side of the contact tip that correspond to the protrusions are plastically deformed toward the guide hole, while the regions on the tip side of the contact tip that correspond to the concave surface portions are not plastically deformed and remain in the concave surface portions, so when the contact tip is viewed from the tip side, the guide hole on the tip side of the contact tip has a triangular cross-sectional shape with its vertices located in the regions that correspond to the concave surface portions. On the other hand, because the cross-sectional shape of the welding wire is circular, when the inner surface of the guide hole and the outer surface of the welding wire come into contact with each other, a linear contact occurs, and the contact area is small even after reshaping, which accelerates wear of the inner surface of the guide hole and is therefore likely to cause poor power supply and, as a result, poor welding.

[0008] Furthermore, in Patent Document 2, the contact tip (electrode tip) is pressed from both radial sides, which tends to flatten the cross-sectional shape of the guide hole (electrode wire through hole). As a result, when the inner surface of the guide hole, which has a flat cross-sectional shape, comes into contact with the outer surface of the welding wire (electrode wire), which has a circular cross-sectional shape, a line contact occurs, which is thought to be likely to result in poor welding, as in Patent Document 1.

[0009] In this regard, Patent Document 3 presses the contact tip radially from three directions, which is thought to make the guide hole closer to a circle. However, since Patent Document 3 has a structure in which the contact tip is pressed from both sides in the center line direction of the guide hole by the upper and lower dies, it is assumed that the contact tip will be removed from the welding torch and set in a re-forming tool. Therefore, when re-forming, it is necessary to stop the equipment and perform the work of attaching and detaching the contact tip, which reduces production efficiency.

[0010] The present invention has been made in view of the above points, and an object of the present invention is to improve production efficiency by in-line reshaping of contact tips that enable high-quality arc welding.

[0011] The first invention is a contact tip remolding device that remoldes a contact tip by pressing molding presses against the outer peripheral surface of the contact tip with a molding unit while a mandrel is inserted into a guide hole in the contact tip. The mandrel has a circular cross section perpendicular to the longitudinal direction. Three or more presses are provided circumferentially aligned along the outer peripheral surface of the mandrel, and the surface of each presser that contacts the outer peripheral surface of the contact tip is an arc-shaped molding surface that corresponds to the cross-sectional shape perpendicular to the center line of the contact tip. The molding unit is characterized by having a guide unit that guides each presser in the radial direction of the mandrel while restricting movement of each presser in the axial direction of the mandrel, and an advancing / retracting mechanism configured to simultaneously apply molding loads from the multiple pressers to the outer peripheral surface of the contact tip while advancing and retracting the multiple pressers in the guide direction of the guide unit.

[0012] According to this configuration, a core rod having a circular cross section in a direction perpendicular to the longitudinal direction is inserted into the guide hole of the contact tip, and the advancing / retracting mechanism advances and retreats multiple presser feet having arc-shaped forming surfaces that correspond to the cross section of the contact tip in a direction perpendicular to the center line, thereby simultaneously applying a forming load to the outer peripheral surface of the contact tip, thereby forming a circular cross section of the guide hole. Furthermore, since the forming unit has a guide part that guides each presser foot in the radial direction of the contact tip, and an advancing / retracting mechanism that advances and retreats the multiple presser feet in the guided direction of the guide part, the contact tip can be reshaped without detaching it from the welding torch.

[0013] A second invention is characterized in that, in the first invention, the molding surface of each presser foot corresponds to the shape of the outer peripheral surface of the contact tip.

[0014] According to this configuration, the molding surface of each presser corresponds to the shape of the outer peripheral surface of the contact tip, so that even if a contact tip has been remolded once, it can be remolded multiple times, thereby improving production efficiency.

[0015] The third invention is characterized in that, in the first invention, when each presser foot is in a position to apply a forming load to the contact tip, the presser feet are arranged at intervals in the circumferential direction of the core rod.

[0016] With this configuration, the presser feet do not interfere with each other when applying a forming load to the contact tip, so the guide hole can be reliably formed, thereby enabling the reshaping of the contact tip to enable high-quality arc welding.

[0017] A fourth invention is characterized in that in the first invention, the tip side of the core rod is formed in a tapered shape so that the diameter decreases as it approaches the tip.

[0018] With this configuration, the diameter of the core rod decreases as it approaches the tip, making it easier to insert the core rod into the guide hole of the contact tip, reducing excessive load on the core rod or welding robot and preventing damage to equipment, thereby improving production efficiency without unnecessary equipment shutdowns.

[0019] A fifth invention is characterized in that, in the first invention, the welding torch further comprises a fixing portion for fixing the welding torch with the contact tip attached thereto.

[0020] According to this configuration, when the contact tip is reshaped, the fixing device fixes the welding torch with the contact tip attached, so the contact tip can be reshaped without being removed from the welding torch. In other words, the reshaping process of the contact tip, which enables high-quality arc welding, can be performed in-line.

[0021] A sixth invention is a welding system comprising a contact tip reshaping device that reshapes a contact tip by pressing multiple forming presser fingers against the outer peripheral surface of the contact tip with a forming unit while a core rod is inserted into the guide hole of the contact tip, a welding robot that holds a welding torch, and a control unit that controls the welding robot and the forming unit. The control unit is configured to: have the welding robot place the contact tip between the presser fingers, then have the forming unit advance the presser fingers to apply a forming load to the outer peripheral surface of the contact tip, and then execute pressing control that controls the forming unit to retract the presser fingers; and then have the welding robot execute a rotation operation that rotates the contact tip around the center line of the contact tip so that the portion of the contact tip corresponding to the portion between adjacent presser fingers faces the forming surface of the contact tip reshaping device; and execute pressing control after the rotation operation.

[0022] The seventh invention is characterized in that, in the sixth invention, when the control unit detects that the molding unit has performed pressing control multiple times, it controls the contact tip remolding device to retract the presser foot, then has the welding robot perform a rotational operation to rotate the contact tip around the center line of the contact tip so that the portion of the contact tip corresponding to the space between adjacent presser feet is in a position where it can be pressed by the presser foot, and then performs pressing control after the rotational operation.

[0023] If the excess metal of the contact tip that was pushed out from the press die during reshaping protrudes from the reshaped contact tip, spatter is more likely to adhere to the contact tip. If spatter adheres to the contact tip, the flow of shielding gas discharged from the welding torch is disrupted by the spatter, making it impossible to adequately protect the weld.

[0024] Therefore, with this configuration, the excess material of the contact tip that was pushed out of the contact surface of each presser die that comes into contact with the outer peripheral surface of the contact tip during the first pressing control is crushed during the second and subsequent pressing controls to smooth the outer peripheral shape of the contact tip, making it difficult for spatter to adhere to the reshaped contact tip. This makes it possible to suppress deterioration of welding quality and to perform contact tip reshaping processing that enables high-quality arc welding.

[0025] According to the present invention, the cross-sectional shape of the guide hole is formed into a circle using the core rod and the presser blades, so that the contact tip can be reshaped to enable high-quality arc welding. Furthermore, because the forming section moves the presser blades back and forth in the radial direction of the contact tip, there is no need to attach or detach the contact tip, and the reshaping process can be performed in-line, improving production efficiency.

[0026] FIG. 1 is a schematic diagram of a welding system according to an embodiment of the present invention. FIG. 2 is a diagram illustrating the structure of a welding torch. FIG. 3 is a perspective view of a contact tip reshaping device according to an embodiment of the present invention, viewed from above on the drive unit side. FIG. 4 is a perspective view of a contact tip reshaping device according to an embodiment of the present invention, viewed from above on the fixed unit side. FIG. 5 is a plan view of a contact tip reshaping device according to an embodiment of the present invention. FIG. 6 is a cross-sectional view taken along line VI-VI in FIG. 5 , with the internal structure of the shaping unit omitted. FIG. 7 is a front view of a contact tip reshaping device according to an embodiment of the present invention. FIG. 8 is a diagram illustrating the structure of the shaping unit according to an embodiment of the present invention. FIG. 9 is an enlarged view of the periphery of a contact tip when a shaping load is being applied by a presser foot. FIG. 10 is a view from above showing the presser foot advanced to the shaping position. FIG. 11 is an enlarged view of the tip end of the mandrel. FIG. 12 is a perspective view corresponding to FIG. 1 , with the welding torch fixed by the fixed unit. FIG. 13 is a cross-sectional view corresponding to FIG. 6 , with the welding torch fixed by the fixed unit, with the internal structure of the shaping unit omitted.

[0027] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that the following description of the preferred embodiments is merely exemplary in nature and is not intended to limit the present invention, its applications, or its uses.

[0028] 1 is a schematic diagram of a welding system WS for reshaping a contact tip according to an embodiment of the present invention. The welding system WS includes a welding robot 1 that holds a welding torch 21, a contact tip reshaping device 3 that reshapes the contact tip 23 by pressing a plurality of forming presser plates 36 against the outer peripheral surface 23c of the contact tip 23 with a drive unit 60 while a core rod 37 is inserted into the guide hole 23a of the contact tip 23, and a control unit 41 that controls the welding robot 1 and the drive unit 60. The welding system WS may further include a welding device 2 and a workpiece holding device 5. The welding robot 1, contact tip reshaping device 3, and workpiece holding device 5 are installed on the floor of a factory that manufactures, for example, automobile parts.

[0029] (Configuration of Welding Robot) As shown in Fig. 1, welding robot 1 is an industrial robot capable of six-axis control and includes a base 11, a robot arm 12, and a robot control device 13. Base 11 is fixed to the floor or the like. By moving robot arm 12, the position and angle of a welding torch 21 held at the tip of robot arm 12 can be controlled. Robot control device 13 is a device for controlling robot arm 12. For example, by performing processing such as teaching in advance, robot control device 13 can cause robot arm 12 to perform a desired operation.

[0030] (Configuration of Welding Apparatus) Welding apparatus 2 includes a welding power source (not shown) and welding torch 21 shown in Fig. 1, and can be configured as a typical gas-shielded arc welding apparatus that has been used conventionally. Welding apparatus 2 is configured to supply welding wire 25 to welding torch 21 at a predetermined speed and to supply shielding gas to the tip of welding torch 21 at a predetermined flow rate. The shielding gas may be, for example, argon gas or carbon dioxide gas. Welding torch 21 is held at the tip of robot arm 12 of welding robot 1.

[0031] 2 , welding torch 21 includes a torch body 22, a contact tip 23, and a nozzle 24, and welding wire 25 is inserted through the inside of torch body 22. Torch body 22 is the main body of welding torch 21.

[0032] The contact tip 23 is threadedly engaged with the torch body 22. An outer peripheral surface 23c at the tip end of the contact tip 23 has a tapered shape with a diameter that decreases toward the tip. A guide hole 23a is formed in the contact tip 23 along a center line 23b of the contact tip. The inner diameter of the guide hole 23a is slightly larger than the outer diameter of the welding wire 25. The role of the contact tip 23 is to supply a welding current to the welding wire 25 and to guide the welding wire 25 to the weld portion of the workpiece W. Therefore, the material of the contact tip 23 must have high conductivity and high hardness, and therefore an expensive copper alloy such as chromium copper is used.

[0033] The nozzle 24 is cylindrical and surrounds the torch body 22 and the contact tip 23, and is screwed onto the torch body 22. The nozzle 24 serves to supply shielding gas to the welding portion.

[0034] The welding wire 25 passes through the interior of the welding torch 21 and is fed out through the guide hole 23a of the contact tip 23. When a welding current is supplied from the contact tip 23, an arc discharge occurs between the tip of the welding wire 25 and the workpiece W, melting the welding wire 25 sequentially from the tip, thereby welding the workpiece W. The material of the welding wire 25 is selected to be similar to that of the workpiece W. In other words, if the workpiece W is made of steel, the welding wire 25 should be made of an iron alloy. The diameter of the welding wire 25 is, for example, about 1.2 mm.

[0035] The welding device 2 also includes a current control unit that controls the output of predetermined welding current and voltage at any timing. The current control unit is configured to selectively supply either pulsed current or non-pulsed current. In the case of pulsed current, the welding current becomes a pulsating current, and droplets generated at the base current, for example, can be separated from the welding wire 25 and transferred to the workpiece W at the peak current.

[0036] 1, the control device 4 includes a control unit 41, which is composed of a microcomputer or the like, and an operation panel 42. The operation panel 42 is used to start and stop the operation of the welding system WS, input various setting values, etc. The control unit 41 is connected to the operation panel 42, and operation information for the operation panel 42 is input. Furthermore, the control unit 41 is connected to the robot control device 13, and the drive units 60 and fixation units 70 of the welding device 2 and contact tip reshaping device 3, and the control unit 41 outputs control signals to these devices.

[0037] (Method of Controlling Contact Tip Reforming Device) The welding robot 1 is provided with a detection means for detecting completion of a predetermined operation. When the detection means detects that the welding robot 1 has completed the predetermined operation, the welding robot 1 outputs a control signal to the control unit 41 of the control device 4 via the robot control device 13.

[0038] Welding device 2 is equipped with a counter that detects the number of welds or the welding time. When the counter detects that the number of welds or the welding time has reached a preset value, welding device 2 outputs a control signal to control unit 41 of control device 4.

[0039] The control unit 41 of the control device 4 receives control signals from the robot control device 13 and the welding device 2 .

[0040] The control unit 41 outputs a control signal to the robot control device 13. The robot control device 13 causes the welding robot 1 to perform a predetermined operation.

[0041] The control unit 41 outputs a control signal to the fixed unit 70 of the contact tip remolding device 3. The fixed unit 70 inputs a voltage to a solenoid valve (not shown) that controls the flow of compressed air in the factory, thereby moving the cylinder 73 forward and backward.

[0042] The control unit 41 outputs a control signal to the drive unit 60 of the contact tip reshaping device 3. The drive unit 60 inputs a voltage to the motor 63 to move the presser foot 36 forward and backward.

[0043] It is also possible to omit the control device 4 and provide an integrated control unit that integrates and operates the robot control device 13, the welding device 2, and the contact tip reshaping device 3. It is also possible to omit the control device 4 and operate the robot control device 13, the welding device 2, and the contact tip reshaping device 3 in a coordinated manner.

[0044] (Configuration of Workpiece Holding Device) As shown in Fig. 1, the welding system WS includes a workpiece holding device 5. The workpiece holding device 5 is configured to be able to hold the workpiece W in a predetermined position, and includes, for example, various clamping devices. Although not shown, the workpiece holding device 5 may be an industrial robot. In this case, the workpiece W can be gripped at the tip of the robot arm 12 and held in a predetermined position.

[0045] (Configuration of Contact Tip Reforming Device) As shown in Figures 3 to 7, the contact tip reforming device 3 includes a forming unit 30 that forms the contact tip 23, a drive unit 60 that drives the forming unit 30, a fixing unit 70 that fixes the welding torch 21, and a support frame 80 to which the forming unit 30, the drive unit 60, and the fixing unit 70 are attached.

[0046] The support frame 80 comprises a lower mounting member 81 to which the molding section 30 is attached, a vertical plate 82 erected at the end of the lower mounting member 81 and to which the drive section 60 is attached, an upper plate 83 to which the fixing section 70 is attached, and a support pillar 84 that fixes and supports the upper plate 83 above the lower mounting member 81.

[0047] 8, the forming unit 30 includes a cylindrical holding member 31, an annular cam 32, a pinion 33 that transmits external power to the cam 32, a sealing member 34 that seals and holds the cam 32 and pinion 33 inside the holding member 31, and a guide member 35 that moves back and forth in the radial direction of the holding member 31. Furthermore, as shown in FIGS. 3 to 7, the forming unit 30 includes a presser foot 36 attached to the guide member 35, a core rod 37, and a base plate 38.

[0048] The holding member 31 includes an upper plate portion 31a having an annular shape centered on the center line CL of the molding portion, an outer peripheral wall portion 31e formed so as to extend downward from the outer peripheral end of the upper plate portion 31a, and an inner peripheral wall portion 31g formed so as to extend downward from the inner peripheral end of the upper plate portion 31a. Three groove-like guide portions 31b that are open upward and have a uniform cross-sectional shape in the radial direction of the holding member 31 and extend radially from the center line CL of the molding portion are formed at equal intervals in the circumferential direction of the holding member 31, all of which have the same cross-sectional shape. In the middle portion of the side wall 31c of the guide portion 31b, a slot 31d is formed in the shape of a groove recessed in the circumferential direction of the holding member 31, extending from the inner periphery to the outer periphery of the holding member 31 along the radial direction of the holding member 31, and the cross section of the slot 31d perpendicular to the radial direction of the holding member 31 is cross-shaped. The guide portion 31b restricts movement of each presser foot 36 in the axial direction of the core rod 37, while guiding the presser foot 36 in the radial direction of the holding member 31. Furthermore, through holes 31f are formed between the multiple guide portions 31b in the outer periphery wall portion 31e.

[0049] The cam 32 is housed in a space surrounded by the outer peripheral wall 31e, inner peripheral wall 31g, and upper plate 31a of the holding member 31. One surface of the cam 32 is formed with radial teeth 32a extending along the radial direction, and the other surface of the cam 32 is formed with spiral grooves 32b with ridges.

[0050] The pinion 33 is disposed coaxially with a through hole 31f formed in the outer peripheral wall portion 31e of the holding member 31, and meshes with radial teeth 32a formed on one surface of the cam 32. The role of the pinion 33 is to be connected to the output shaft 62 of the gear box 61 and to transmit the rotational force of the motor 63 to the cam 32.

[0051] The sealing member 34 has an annular shape and is fastened to the holding member 31 to hold the cam 32 and the pinion 33 from below so that they do not come off the holding member 31.

[0052] The guide member 35 has a presser foot 36 attached to its upper surface, and a rib 35b protruding away from the side surface 35a of the guide member 35 is formed along the direction in which the guide member 35 advances and retreats. The rib 35b formed on the side surface 35a of the guide member 35 fits into a slot 31d formed in the guide portion 31b of the holding member 31, thereby restricting the movement of the guide member 35 in the axial and circumferential directions of the contact tip 23 and allowing it to advance and retreat in the radial direction of the contact tip 23. In addition, teeth 35c are formed on the lower surface of the guide member 35, perpendicular to the direction in which the guide member 35 advances and retreats. The teeth 35c on the lower surface of the guide member 35 mesh with the inner surface of a spiral-shaped groove 32b formed on the other surface of the cam 32.

[0053] Three or more presser plates 36 attached to the guide member 35 are provided so as to be lined up in the circumferential direction along the outer circumferential surface of the core rod 37. The surface of each presser plate 36 that comes into contact with the outer circumferential surface 23c of the contact tip 23 is a molding surface 36a that is curved in an arc shape corresponding to the cross-sectional shape of the contact tip in a direction perpendicular to the center line 23b.

[0054] The core rod 37 has a circular cross section perpendicular to the longitudinal direction. The tip of the core rod 37 has the same outer diameter as the welding wire 25. The core rod 37 extends upward and is supported by a core rod support member 372 via a retainer 371. The core rod support member 372 is fixed to the base plate 38 together with the holding member 31. Furthermore, the base plate 38 is attached to a lower mounting member 81 of the support frame 80. The tip of the core rod 37 is located above the forming surfaces 36a of each presser foot 36 and below the upper plate 83 of the support frame 80.

[0055] The drive unit 60 includes a gearbox 61 and a motor 63. The output shaft of the motor 63 is connected to the gearbox 61, and the rotation speed of the motor 63 is reduced to an appropriate rotation speed, and the driving force is transmitted from the output shaft 62 of the gearbox 61 to the pinion 33. The drive unit 60 is fixed to a vertical plate 82 of the support frame 80.

[0056] (Configuration of the Advance / Retract Mechanism) Referring to Figure 8, a mechanism for advancing and retracting the guide member 35 to which the presser foot 36 is attached will be described in accordance with an embodiment of the present invention. The presser foot 36 is omitted from Figure 8. By rotating the output shaft 62 of the gearbox 61 in the direction of arrow A, the pinion 33 drives the radial teeth 32a formed on one surface of the cam 32, causing the cam 32 to rotate in the direction of arrow B around the center line CL of the forming portion. The inner surface of the spiral groove 32b formed on the other surface of the cam 32 engages with the teeth 35c formed on the underside of the guide member 35. Therefore, when the pinion 33 rotates in the direction of arrow A, the guide member 35 to which the presser foot 36 is attached advances in the direction of arrow C, which is the forming direction of the contact tip 23. Furthermore, when the pinion 33 is rotated in the opposite direction of arrow A, the guide member 35 to which the presser foot 36 is attached retreats in the opposite direction of arrow C. Since each guide member 35 can be moved forward and backward simultaneously by the common cam 32, the presser feet 36 attached to each guide member 35 can be moved simultaneously at the same speed. Therefore, a forming load can be applied to the outer peripheral surface 23c of the contact tip 23 simultaneously.

[0057] Although the motor 63 is used as the power source for the drive unit 60 in the embodiment of the present invention, a cylinder may be used as the power source. Also, instead of a reciprocating mechanism using the cam 32, a mechanism for advancing and retracting each presser foot 36 via a rack and pinion or link may be used.

[0058] (Control of Contact Tip Reforming Device) The control unit 41 of the control device 4 controls the welding robot 1 and the contact tip reforming device 3 as follows. First, the welding robot 1 positions the contact tip 23 between the presser feet 36 via output from the robot control device 13. Once positioning is complete, the control unit 41 outputs the drive unit 60 of the contact tip reforming device 3 to advance the presser feet 36, applying a forming load to the outer circumferential surface 23c of the contact tip 23. After applying the forming load for a predetermined time, the drive unit 60 of the contact tip reforming device 3 retracts the presser feet 36, and the welding robot 1 rotates the contact tip 23 around the center line 23b of the contact tip so that the joints between the presser feet 36 on the contact tip 23 coincide with the position of the forming surface 36a of each presser foot 36. The drive unit 60 then again advances the presser feet 36, applying a forming load to the outer circumferential surface 23c of the contact tip 23 for a predetermined time. Finally, the drive unit 60 moves the pressers 36 backward, causing the welding robot 1 to assume a standby position to wait for the next instruction.

[0059] Fixing unit 70 is used to fix welding torch 21 and includes a base 71, a gripping unit 72 that clamps torch body 22 or contact tip 23 from two directions, and a cylinder 73 that moves gripping unit 72 back and forth. Grip unit 72 includes a fixed-side member 72a attached to base 71 and a driving-side member 72b attached to cylinder 73. The clamping surfaces of fixed-side member 72a or driving-side member 72b may be filed or knurled.

[0060] (Method for remolding contact tip) The method for remolding contact tip 23 according to this embodiment is a method for remolding contact tip 23 by inserting core rod 37 into guide hole 23a of contact tip 23 and pressing molding presser foot 36 against outer peripheral surface 23c of contact tip 23 with drive unit 60.

[0061] First, the welding robot 1 brings the contact tip 23 that has been welded a predetermined number of times or for a predetermined time to the contact tip reshaping device 3, and makes the welding robot 1 take a contact tip reshaping posture with the core rod 37 inserted into the guide hole 23a of the contact tip 23.

[0062] Next, the output shaft 62 of the gear box 61 is rotated to move each presser foot 36 forward toward the contact tip 23, and the molding surface 36a of each presser foot 36 is pressed against the contact tip 23, thereby performing diameter reduction molding to reduce the diameter of the guide hole 23a of the contact tip 23. Thereafter, the output shaft 62 of the gear box 61 is reversed to move each presser foot 36 backward from the contact tip 23.

[0063] Next, during the diameter reduction molding, the contact tip 23 is rotated around the center line 23b of the contact tip so that the position of the excess material of the contact tip 23 extruded from the molding surface 36a between each presser foot 36 overlaps with the molding surface 36a.

[0064] Then, the output shaft 62 of the gear box 61 is rotated again to move each presser foot 36 forward toward the contact tip 23, and the molding surface 36a of each presser foot 36 is pressed against the contact tip 23, thereby smoothing out the excess material that has been extruded and protruded onto the outer circumferential surface 23c of the contact tip 23. Thereafter, the output shaft 62 of the gear box 61 is reversed to move each presser foot 36 back from the contact tip 23.

[0065] Furthermore, the contact tip 23 is inverted around the center line 23b of the contact tip so that the excess metal of the contact tip extruded from the molding surface 36a between the presser blades 36 during the smoothing molding is positioned on the molding surface 36a, and smoothing molding is performed again. Thereafter, the output shaft 62 of the gearbox 61 is inverted to move the presser blades 36 back from the contact tip 23.

[0066] Finally, the core rod 37 is removed from the guide hole 23a of the contact tip 23, and the welding robot 1 is made to assume a standby position.

[0067] Alternatively, the welding system WS may include a welding robot 1 that holds the welding torch 21, a contact tip reshaping device 3 that reshapes the contact tip 23 by pressing a plurality of forming presser plates 36 against the outer peripheral surface 23c of the contact tip 23 with a forming unit 30 while a core rod 37 is inserted into the guide hole 23a of the contact tip 23, and a control unit 41 that controls the welding robot 1 and the forming unit 30. After the welding robot 1 places the contact tip 23 between the presser plates 36, the control unit 41 executes pressing control by causing the forming unit 30 to advance the presser plates 36 to apply a forming load to the outer peripheral surface 23c of the contact tip 23, and then controls the forming unit 30 to retreat the presser plates 36, and then causes the welding robot 1 to perform a rotational operation to rotate the contact tip 23 around the center line 23b of the contact tip 23 so that the portion of the contact tip 23 corresponding to the space between adjacent presser plates 36 faces the shaping surface 36a of the contact tip reshaping device 3, and then executes pressing control after the rotational operation.

[0068] When a forming load is applied to the contact tip 23, the material constituting the contact tip 23 undergoes work hardening due to plastic deformation. Table 1 compares the measured values ​​and changes in the inner diameter of the guide hole 23a for a new contact tip 23 that has not been reshaped and a contact tip 23 that has been reshaped according to the present invention, before welding the workpiece W and after welding multiple workpieces W and reaching the time for reshaping. Table 1 shows that the change in the inner diameter of the reshaped guide hole 23a is smaller than the change in the inner diameter of the guide hole 23a without reshaping. Therefore, it can be said that the reshaped contact tip 23 is less susceptible to wear. In other words, using a reshaped contact tip 23 can extend the interval until the next reshaping is required, thereby improving production efficiency.

[0069]

[0070] (Effects of the Embodiment) As described above, with the contact tip reshaping device 3 according to this embodiment, a core rod 37 having a circular cross section perpendicular to the longitudinal direction is inserted into the guide hole 23a of the contact tip 23, and a forming load is simultaneously applied to the outer peripheral surface 23c of the contact tip 23 by the multiple pressers 36 having arc-shaped forming surfaces 36a that correspond to the cross-sectional shape perpendicular to the center line 23b of the contact tip at the surface that contacts the outer peripheral surface of the contact tip 23, thereby forming the cross-sectional shape of the guide hole 23a into a circular shape. Furthermore, the forming unit 30 includes guide portions 31b that guide the pressers 36 in the radial direction of the contact tip 23 and an advancing / retracting mechanism that advances and retracts the multiple pressers 36 in the guiding direction of the guide portions 31b. Therefore, reshaping can be performed without removing the contact tip 23. In other words, the pressers 36 and the core rod 37 form the cross-sectional shape of the guide hole 23a into a circular shape, thereby enabling the reshaping of the contact tip 23, which enables high-quality arc welding. Furthermore, since the advancing / retracting mechanism advances and retreats each presser foot 36 in the radial direction of the contact tip 23, there is no need to attach or detach the contact tip 23, and the remolding process can be brought in-line, improving production efficiency.

[0071] As shown in FIG. 9, the molding surface 36 a of each presser foot 36 may have a shape corresponding to the shape of the outer peripheral surface 23 c of the contact tip 23 .

[0072] According to this configuration, the molding surface 36a of each presser foot 36 corresponds to the shape of the outer peripheral surface 23c of the contact tip 23, so that even if the contact tip 23 has been remolded once, it can be remolded multiple times.

[0073] As shown in FIG. 10, the presser plates 36 may be arranged at a distance D from each other in the circumferential direction of the core rod 37 when they are in a position where they apply a forming load to the contact tip 23 .

[0074] According to this configuration, when a molding load is applied to the contact tip 23, the presser plates 36 do not interfere with each other, so that the guide hole 23a can be reliably molded.

[0075] As shown in FIG. 11, the tip side of the core rod 37 may be tapered so that the diameter decreases as it approaches the tip.

[0076] With this configuration, the diameter of the core rod 37 decreases as it approaches the tip, making it easier to insert the core rod 37 into the guide hole 23a of the contact tip 23, thereby reducing excessive load on the core rod 37 or the welding robot 1 and suppressing damage to the equipment.

[0077] As shown in FIGS. 12 and 13, the welding torch 21 may further include a fixing portion 70 for fixing the welding torch 21 with the contact tip 23 attached thereto.

[0078] According to this configuration, when the contact tip 23 is reshaped, the fixing portion 70 fixes the welding torch 21 with the contact tip 23 attached, so that the contact tip 23 can be reshaped without being removed from the welding torch 21.

[0079] In addition, when the control unit 41 detects that the molding unit 30 has performed pressing control multiple times, it may control the contact tip remolding device 3 to retract the pressure plate 36, and then have the welding robot 1 perform a rotational operation to rotate the contact tip 23 around the center line 23b of the contact tip 23 so that the portion of the contact tip 23 corresponding to the space between adjacent pressure plates 36 is in a position where it can be pressed by the pressure plate 36, and then perform pressing control after the rotational operation.

[0080] According to this configuration, the excess material of the contact tip 23 that is pushed out of the surface of each presser 36 that contacts the outer peripheral surface 23c of the contact tip 23 during the first pressing control is crushed during the second and subsequent pressing controls to level the outer peripheral shape of the contact tip 23, making it less likely for spatter to adhere to the contact tip 23 after it has been remolded.

[0081] (Other Embodiments) Furthermore, the core rod 37 may be supported so as to be capable of translating radially relative to the core rod support member 372, or may be supported so as to be rotatable about the central axis of the core rod 37 relative to the core rod support member 372. This configuration reduces snagging when inserting or removing the contact tip 23 into or from the core rod 37, making it easier for the core rod 37 to pass through the guide hole 23a, thereby reducing excessive load on the core rod 37 or the welding robot 1.

[0082] Furthermore, the surface of the core rod 37 may be provided with a file-like unevenness. With this configuration, an oxide film formed on the inner peripheral surface of the guide hole 23a of the contact tip 23 can be removed, and therefore the contact electrical resistance between the inner peripheral surface of the guide hole 23a of the contact tip 23 and the outer peripheral surface of the welding wire 25 can be kept small.

[0083] The contact tip reshaping device 3 may include a heater for heating the contact tip 23 before reshaping. With this configuration, the contact tip 23 is heated before reshaping, and the contact tip 23 is reshaped in a state where the yield stress of the material of the contact tip 23 is reduced, thereby reducing excessive load on the presser foot 36 and the drive unit 60.

[0084] As described above, the contact tip reshaping device according to the present invention can be used, for example, when reshaping a contact tip whose inner circumferential surface of the guide hole has been worn.

[0085] WS welding system 1 welding robot 21 welding torch 23 contact tip 23a guide hole 23b center line of contact tip 23c outer peripheral surface 3 contact tip reshaping device 30 shaping portion 31b guide portion 36 presser foot 36a shaping surface D spacing 37 core rod 41 control portion 70 fixing portion

Claims

1. A contact tip remolding device that remoldes a contact tip by pressing molding pressurized plates against the outer peripheral surface of a contact tip with a molding unit while a core rod is inserted into a guide hole of the contact tip, wherein the core rod has a circular cross section in a direction perpendicular to the longitudinal direction, three or more pressurized plates are provided circumferentially aligned along the outer peripheral surface of the core rod, the surface of each pressurized plate that contacts the outer peripheral surface of the contact tip is a molding surface that is curved in an arc shape corresponding to the cross-sectional shape in a direction perpendicular to the center line of the contact tip, and the molding unit comprises a guide unit that guides each pressurized plate in the radial direction of the core rod while restricting movement of the pressurized plates in the axial direction of the core rod, and an advancing and retreating mechanism configured to simultaneously apply a molding load from the multiple pressurized plates to the outer peripheral surface of the contact tip while moving the multiple pressurized plates back and forth in the guide direction of the guide unit.

2. A contact tip remolding device according to claim 1, characterized in that the molding surface of each of the presser feet corresponds to the shape of the outer peripheral surface of the contact tip.

3. A contact tip remolding device as described in claim 1, characterized in that the presser feet are spaced apart from one another in the circumferential direction of the core rod when they are in a position to apply a molding load to the contact tip.

4. A contact tip remolding device according to claim 1, characterized in that the tip side of the core rod is formed in a tapered shape so that the diameter decreases as it approaches the tip.

5. The contact tip reforming device according to claim 1, further comprising a fixing portion for fixing the welding torch with the contact tip attached thereto.

6. A welding system comprising a contact tip reshaping device that reshapes a contact tip by pressing a plurality of forming pressurizers against the outer peripheral surface of the contact tip with a forming unit while a core rod is inserted into the guide hole of the contact tip, a welding robot that holds a welding torch, and a control unit that controls the welding robot and the forming unit, wherein the control unit executes pressing control such that, after the welding robot has placed the contact tip between the pressurizers, the forming unit advances the pressurizers to apply a forming load to the outer peripheral surface of the contact tip and then controls the forming unit to retreat the pressurizers, and then causes the welding robot to perform a rotational operation to rotate the contact tip around the center line of the contact tip so that the portion of the contact tip corresponding to the portion between adjacent pressurizers faces the forming surface of the contact tip reshaping device, and executes the pressing control after the rotational operation.

7. A welding system as described in claim 6, wherein, when the control unit detects that the forming unit has performed the pressing control multiple times, it controls the contact tip re-forming device to retract the presser foot, then causes the welding robot to perform a rotational operation to rotate the contact tip around the center line of the contact tip so that the portion of the contact tip corresponding to the space between adjacent presser feet is positioned so that it can be pressed by the presser foot, and then performs the pressing control after the rotational operation.

Images