METHOD FOR JOINING OR MACHINING AND APPARATUS THEREFOR

Abstract

A method for joining or machining, in particular a friction stir welding method, using an apparatus, in which a tool, in particular a friction stir welding tool, is driven via a spindle with a spindle axis. To achieve high process reliability, even when the method is applied in poorly accessible positions, an adapter, in particular an angle head, is arranged between the spindle and the tool so that the tool axis about which the tool rotates does not coincide with the spindle axis. A force acting on the spindle is measured and the method is controlled depending on the force measured at the spindle. The apparatus for joining or machining, in particular for friction stir welding, includes a headstock with a spindle, which can be rotated about a spindle axis and a tool, in particular a friction stir welding tool, which can be driven about a tool axis by the spindle.

Claims

1. A method for friction stir welding, using an apparatus, wherein a tool, which is embodied as a friction stir welding tool, is driven via a spindle with a spindle axis, wherein an adapter, in particular an angle head, is arranged between the spindle and the tool so that the tool axis about which the tool rotates does not coincide with the spindle axis, wherein a force acting on the spindle is measured and the method is controlled depending on the force measured at the spindle.

2. The method according to claim 1, wherein the control is regulated depending on the force measured at the spindle and on a machine constant assigned to the adapter.

3. The method according to claim 1, wherein forces in multiple spatial directions are measured at the spindle and a control occurs depending on distances of the tool from the spindle in multiple spatial directions.

4. The method according to claim 1, wherein the measured force is multiplied by a machine constant which depends on a distance of the tool from the spindle, before the measured force enters into the control.

5. The method according to claim 1, wherein the adapter is detachably connected to the spindle and a force is measured by means of a force-measuring device arranged on the adapter.

6. The method according to claim 1, wherein the tool axis is arranged at an angle of 15° to 165°, preferably approximately 90°, to the spindle axis.

7. The method according to claim 1, wherein at least two friction stir welding tools, are arranged on the adapter and a control occurs depending on the force measured at the spindle and on which of the friction stir welding tools is used.

8. An apparatus for friction stir welding, comprising a headstock with a spindle which can be rotated about a spindle axis and a tool, which can be driven about a tool axis by the spindle, which tool is embodied as a friction stir welding tool, wherein an adapter, in particular an angle head, is arranged between the spindle axis and the tool axis so that the spindle axis does not coincide with the tool axis, wherein at least one force sensor is arranged in the region of the spindle to register a force acting on the spindle, wherein the apparatus is embodied for controlling a friction stir welding method, based on the measured force, in particular for carrying out a method according to claim 1.

9. The apparatus according to claim 8, wherein a force-measuring system is provided for registering forces in different spatial directions.

10. The apparatus according to claim 8 wherein, wherein the apparatus is embodied for controlling the method depending on a distance of the tool from the spindle, and the control can be adjusted to varying distances, in particular due to different adapters.

Description

[0022] Additional features, benefits and effects of the invention follow from the exemplary embodiment described below. The drawing which is thereby referenced shows the following:

[0023] FIG. 1 An apparatus for carrying out a method according to the invention.

[0024] FIG. 1 schematically shows an apparatus 1 according to the invention for carrying out a method according to the invention in a perspective illustration, wherein the apparatus 1 illustrated in the exemplary embodiment is embodied for carrying out a friction stir welding method.

[0025] Visible is a spindle 2 connected to a motor, not illustrated, via which spindle 2 a drive occurs, wherein the spindle 2 is connected to a tool 6 via an adapter embodied as an angle head 3, which tool 6 is connected to the angle head 3 such that the tool 6 can be rotated about a tool axis 5. The tool axis 5 is thereby aligned with the spindle axis 4 at an angle α of approximately 90° and the tool 6 is embodied as a friction stir welding tool. A pressing by the tool 6 in the direction of the tool axis 5 can thereby occur by a movement of the spindle 2 in the direction of the tool axis 5.

[0026] An advance of the tool 6 on a plane perpendicular to the tool axis 5 can also be implemented through a corresponding movement of the spindle 2.

[0027] In a friction stir welding method, high forces act on the tool 6, in particular an axial tool force 7 due to the pressing of the friction stir welding tool in the direction of the tool axis 5 against a workpiece, not illustrated, on which a weld seam is to be formed. Furthermore, during a movement along an advancing direction 12, a radial tool force 8 that is caused by the advance and, due to a rotation of the tool 6 about the tool axis 5, a moment, which additionally subjects the tool 6 to torsion stress, act on the tool 6. The forces are transmitted to the tool 6 at a force transmission point on the tool tip with which the weld seam is formed.

[0028] At the spindle 2, that is, at a position spaced apart from the tool 6, force-measuring devices, for example force-measuring sensors 9, are arranged which are illustrated by way of example in FIG. 1 and with which an axial spindle force 10 and a shearing spindle force 11 can be measured. The force-measuring devices can, for example, be positioned between the spindle 2 and headstock or at the angle head 3 or on the adapter itself in the region of the spindle 2. To prevent damage to the tool 6, the loads acting on the tool 6 are indirectly deduced via the force-measuring devices arranged at the spindle 2. For this purpose, the forces measured on the force-measuring devices at the spindle 2 are converted into forces acting on the tool 6, wherein a conversion thereby occurs depending on a distance of the tool 6 or the force transmission point from the spindle 2, in particular a spindle nose, for which the forces and moments at the spindle 2 are typically known, or on a distance of the force-measuring devices from the tool 6 both in the direction of the spindle axis 4 and also in the direction of the tool axis 5, possibly also in other spatial directions. Forces and moments occurring in all spatial directions are normally measured so that the forces acting on the tool 6 can be accurately deduced. As a result, collisions of the tool 6 in particular can be reliably detected, and the method can be regulated in a timely manner before the tool 6 or the apparatus 1 is damaged. Additionally, by including a distance of the force transmission point from the spindle nose in the control, for example via a machine constant by which the axial spindle force 10 and the shearing spindle force 11 are multiplied, it is then also possible to deduce bending moments acting on the spindle 2, if said bending moments cannot be registered directly, in order to determine a load on a spindle bearing. The method can thus be regulated if it is determined that permissible loads of the spindle bearings have been exceeded, before the spindle bearings are damaged.

[0029] In the method, measured forces are continuously compared with limit values which correspond to maximum permissible loads of the apparatus 1 and the tool 6. When a measured value that exceeds a limit value is registered by the force-measuring device, the control occurs in that a pressing force in the direction of the tool axis 5, an advancing speed on a plane perpendicular to the tool axis 5, and/or a rotation speed of the tool 6 about the tool axis 5 are reduced until loads at the spindle 2 and at the tool 6 within permissible limit values can be deduced based on the forces measured on the force-measuring devices.

[0030] With a method according to the invention and a corresponding apparatus 1, a friction stir welding method in particular can be carried out in an efficient manner even in poorly accessible positions, wherein damage to the friction stir welding tool and to the apparatus 1 can be reliably prevented.

[0031] On the one hand, a collision of the tool 6 with a component can be reliably detected. On the other hand, damage at the spindle 2 is prevented, in particular in the spindle bearings due to bending moments which are caused by long lever arms of the angle head 3.

[0032] In addition to friction stir welding, the method according to the invention and the corresponding apparatus 1 can also be used for milling, lathing and/or drilling, wherein corresponding advantages are likewise obtained.