GRINDING WELDING ELECTRODES

Abstract

Grinding a rod-shaped welding electrode includes forming a contact line at a contact surface region of a rotating grinding tool, moving the rotating grinding tool and the welding electrode relative to one another in order to grind a surface of the welding electrode, pressing the welding electrode in an axial direction against an abrasive contact surface region of the rotating grinding tool, and, during relative movement between the rotating grinding tool and the welding electrode, moving the rotating grinding tool along a curved path in a plane of movement which extends transversely to the contact line and which includes a longitudinal axis of the welding electrode. A holder for the rotating grinding tool is arranged on a coupler mechanism which is provided with two actuating drives enabling the holder to be moved to any point within an operating range of a plane of movement.

Claims

1. A method for grinding a rod-shaped welding electrode, comprising: pressing a contact surface region of the welding electrode in an axial direction of the welding electrode against an abrasive contact surface region of the rotating grinding tool, so that a contact line is formed at the contact surface region of the rotating grinding tool; and moving the rotating grinding tool and the welding electrode relative to one another in order to grind a surface of the welding electrode along a curved path in a plane of movement which extends transversely to the contact line and which includes the longitudinal axis of the welding electrode, wherein a holder for the rotating grinding tool is arranged on a coupler mechanism which is provided with two actuating drives enabling the holder to be moved to any point within an operating range of a plane of movement.

2. The method according to claim 1, wherein the abrasive contact surface region of the rotating grinding tool is concavely curved and the contact line is concavely curved.

3. The method according to claim 1, wherein the abrasive contact surface region of the grinding tool is formed by a concavely curved, annular groove on a side face of a grinding wheel.

4. The method according to claim 1, wherein the abrasive contact surface region of the grinding tool is formed by a peripheral surface of a grinding wheel.

5. The method according to claim 4, wherein a circumferential surface of the grinding wheel is concavely curved in an axial direction of the grinding wheel.

6. The method according to claim 1, wherein a surface region of the welding electrode and the abrasive contact surface region of the rotating grinding tool are pressed resiliently against one another.

7. A device for grinding a rod-shaped welding electrode, comprising: a rotating grinding tool; a rotary drive coupled to the rotating grinding tool; a pressing device that presses a surface region of the welding electrode to an abrasive contact surface region of the rotating grinding tool, wherein a contact surface area of the grinding tool forms a contact line; a moving device that moves the rotating grinding tool and the welding electrode relative to each other in order to grind a surface of the welding electrode, wherein the pressing device presses the welding electrode in an axial direction against the abrasive contact surface region and wherein the moving device moves the rotating grinding tool relative to the welding electrode on a curved path in a plane of movement, which extends transversely to the contact line and is parallel to a longitudinal axis of the welding electrode; and a holder for the rotating grinding tool that is arranged on a coupler mechanism which is provided with two actuating drives that enable the holder to be moved to any point within an operating range of a movement plane.

8. The device according to claim 7, wherein the contact line is concavely curved.

9. The device according to claim 8, wherein the abrasive contact surface area of the grinding tool is formed by a concave, ring-shaped groove on the side face of a grinding wheel.

10. The device according to claim 7, wherein the abrasive contact surface region of the rotating grinding tool is held resiliently relative to the welding electrode.

11. The device according to claim 7, wherein the device is an integral part of a welding head or a welding gun.

12. The method according to claim 3, wherein a surface region of the welding electrode and the abrasive contact surface region of the rotating grinding tool are pressed resiliently against one another.

13. The method according to claim 4, wherein a surface region of the welding electrode and the abrasive contact surface region of the rotating grinding tool are pressed resiliently against one another.

14. The method according to claim 5, wherein a surface region of the welding electrode and the abrasive contact surface region of the rotating grinding tool are pressed resiliently against one another.

15. The method of claim 2, wherein a circumferential surface of the grinding tool moves past an end face of the welding electrode.

16. The device according to claim 8, wherein the abrasive contact surface area of the grinding tool is formed by a concavely curved peripheral surface of a grinding wheel.

17. The device according to claim 8, wherein the abrasive contact surface region of the rotating grinding tool is held resiliently relative to the welding electrode.

18. The device according to claim 9, wherein the abrasive contact surface region of the rotating grinding tool is held resiliently relative to the welding electrode.

19. The device according to claim 16, wherein the abrasive contact surface region of the rotating grinding tool is held resiliently relative to the welding electrode.

20. The device of claim 8, wherein a circumferential surface of the grinding tool moves past an end face of the welding electrode.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Further practical embodiments and advantages of the system described herein are described below in connection with the drawings.

[0024] FIG. 1 shows a sectional view of a first embodiment of a grinding wheel with hub.

[0025] FIG. 2 shows a second embodiment of a grinding wheel with drive motor.

[0026] FIG. 3 shows a holder for the drive motor of the grinding wheel from FIG. 2 with schematically depicted welding electrodes.

[0027] FIG. 4 shows a front view of the holder from FIG. 3.

[0028] FIG. 5 shows a side view of the holder shown in FIGS. 3 and 4.

[0029] FIG. 6 shows the coupler mechanism from FIGS. 3-5 in a first position.

[0030] FIG. 7 shows the coupler mechanism from FIG. 6 in a second position.

[0031] FIG. 8 shows a side view corresponding to FIG. 5 with the position of the coupler mechanism from FIG. 7.

[0032] FIG. 9 shows a schematic representation of the coupler mechanism in a position that corresponds to the position shown in FIG. 7.

[0033] FIG. 10 shows three representations of the coupler mechanism corresponding to FIG. 9 in three different positions for machining the upper welding electrode.

[0034] FIG. 11 shows corresponding representations of the coupler mechanism in positions for machining the lower welding electrode as in FIG. 10.

DETAILED DESCRIPTION OF VARIOUS EMBODIMENTS

[0035] FIG. 1 shows a first embodiment of a grinding wheel 1, which forms the grinding tool for carrying out the method described here. The grinding wheel 1 is clamped in a rotationally fixed manner on a hub 2, which is rotated about its axis of rotation 3 using a drive motor (not shown). Grinding wheels are usually rotated at speeds of over 1,000 revolutions per minute. The grinding wheel 1 is intended for wheel-face grinding and has on an upper side face of the grinding wheel 1, which extends perpendicular to the axis of rotation 3, a flat annular groove 4 with a slightly concave curve. The grinding wheel 1 is circular in plan view. The groove 4, which is concave in the radial direction of the grinding wheel 1, extends in an annular area on the circular grinding wheel 1. A rod-shaped welding electrode 5 is shown schematically in the right-hand half of FIG. 1. The welding electrode 5 has a longitudinal axis 6 and a cap-shaped end face, which is pressed in an axial direction into the annular groove 4 of the grinding wheel 1 with a concave surface. Grinding removes dirt from the end face and produces a uniform surface with a fine grit marks caused by the abrasive particles.

[0036] FIG. 2 shows an alternative embodiment of a grinding wheel 7. The grinding wheel 7 is intended for peripheral grinding. This means that the grinding wheel 7 has abrasive particles, preferably diamond particles or CBN particles, on a circumferential surface 9 of the grinding wheel 7, which is concave in the axial direction. A shaft 10 is integrally formed on the grinding wheel 7, which is rotated at high speed around the axis of rotation 8 by a drive motor 11. FIG. 2 also shows the welding electrode 5, which is pressed against the concave circumferential surface 9 of the grinding wheel 7 in a radial direction. This also establishes a linear contact along a concave contact line between the grinding wheel 7 and the welding electrode 5.

[0037] FIG. 3 shows an embodiment of a holder for the drive motor 11 of a grinding wheel 7. In the embodiment of FIG. 3, the grinding wheel 7 is guided along a curved path that lies in a plane that is essentially perpendicular to the contact line. The curvature of the contact line between the grinding wheel 7 and the welding electrode 5 and the curvature of the curved machining path overlap and give the face of the welding electrode 5 a convex shape. The curved machining path is generated using a coupler mechanism.

[0038] Components of the holder of the drive motor 11 for the grinding wheel 7 are shown in FIG. 6 in an isolated manner. In the embodiment of FIG. 3, the holder for the drive motor 11 is formed by a free end 14 of a first coupler 15, the other end of which is connected to a first crank 16 of a first actuating drive 18 via a first joint 17. In the embodiment shown, the first coupler 15 has the shape of a cranked lever. A second coupler 19 is connected at one end via a second joint 21 to a second crank 20 of a second actuating drive 22 and via a third joint 23 to the first coupler 15. The third joint 23 is located approximately in the area of the crank of the first coupler 15. In FIG. 3 it can be seen that the stepper motors 18 and 22 are attached to a support plate 24. By turning the cranks 16 and 20 using the stepper motors 18, 22, the free end 14 of the first coupler 15, which forms the holder for the drive motor 11 of the grinding wheel 7, can be moved within an operating range in a plane parallel to the support plate 24.

[0039] The support plate 24 is located on the side of an electrode holder 25 of a welding device, which is shown as a transparent plate in FIG. 3 for reasons of clarity and carries two welding electrodes 5, 5. As the grinding wheel 7 can be moved essentially freely in a plane perpendicular to the axis of rotation of the grinding wheel 7 by the coupler mechanism, the grinding wheel 7 can be moved both to the upper welding electrode 5 and to the lower welding electrode 5 in order to machine the end face with the grinding wheel 7

[0040] After machining, in which the coupler mechanism has approximately the position shown in FIG. 6, the coupler mechanism can be moved to the position shown in FIG. 7, in which the grinding wheel 7 and the drive motor 11 of the grinding wheel 7 are at the maximum distance from the welding electrodes 5, 5. In a rest position shown in FIG. 7, the grinding wheel 7 does not interfere with the welding process executed by the welding electrodes, as can be seen in FIG. 8. If reworking of the end faces of the welding electrodes 5, 5 is required, the grinding wheel is moved back to the position shown in FIGS. 3-5.

[0041] FIG. 9 shows the rotary position of actuating drives, which move the grinding wheel to the position shown in FIG. 8. FIG. 9 is only a schematic representation of the coupler mechanism. An axis of rotation 26 of the a actuating drive and an axis of rotation 27 of a second actuating drives are shown here. The couplers 15, 19 and the cranks 16, 20 are merely shown as lines. Furthermore, a machining path 29 for the end face of the upper welding electrode 5 and a machining path 30 for the end face of the lower welding electrode 5 are shown schematically. When the axis of rotation 8 of the grinding wheel moves along the machining path 29 or the machining path 30, the concavely curved circumferential surface 9 of the grinding wheel 7 has a linear contact with the respective one of the welding electrodes 5, 5 to be machined. For both cranks 16, 20, the crank angle is shown in relation to a zero position extending horizontally to the right. In FIG. 9, the crank angle between the first crank 16 and the zero position is 328.91. The crank angle of the second crank 20 in the position of the coupler mechanism in FIG. 9 has a value of 148.97.

[0042] Starting from the position shown in FIG. 9, the cranks 16, 20 can be rotated in order to move the axis of rotation 8 of the grinding wheel, for example, into the vicinity of the machining path 29 of the upper welding electrode 5.

[0043] FIGS. 10A, B and C show three positions of the coupler mechanism during machining of the upper welding electrode. It can be seen that the machining path 29 is concavely curved so that the axis of rotation 8 of the grinding wheel moves along a concave machining path 29 to cause the circumferential surface to move along the concave machining path 29 past the end face of the welding electrode 5. The concave contour of the peripheral surface of the grinding wheel is superimposed on the concave path of movement of the axis of rotation 8 of the grinding wheel and in this way produces a cap-shaped contour on the end face of the upper welding electrodes 5.

[0044] FIG. 11 shows in representations A, B and C three positions of the axis of rotation 8 of the grinding wheel on the machining path 30 for the lower welding electrode 5.

[0045] If the circumferential surface of the welding electrode is not concave but convex in the axial direction, the movement sequence of the coupler mechanism can be reversed, i.e. the grinding wheel is moved along a convex path towards the welding electrode during grinding and pressed into an end face of the welding electrode until the grinding wheel reaches the center, and the grinding wheel is then moved away from the welding electrode in the axial direction again. The result is not a crowned end face but a depression in the center of the end face of the welding electrode. In this way, the end face of the welding electrode is provided with an annular surface projecting in the axial direction on the outer periphery, which contacts the workpiece during welding.

[0046] The features of the invention disclosed in the present description, in the drawings and in the claims may be essential, both individually and in any combination, for the realization of the invention in its various embodiments. The invention is not limited to the described embodiments. It can be varied within the scope of the claims and taking into account the knowledge of the person skilled in the art.