JOINING TOOL FOR PRESSING A DISK TO A SHAFT, AND ROTOR SHAFT FOR AN ELECTRIC MACHINE

Abstract

A joining tool (10) is provided for pressing a disk (12) to a shaft (14) that has opposite first and second ends. The first end (18) of the shaft (14) is received in a press table (22) and the second end (24) of the shaft (14) is received in a centering receptacle (26). A press plate (34) axially presses the disk (12) onto the shaft (14). A resilient ram (40) is provided on a side of the press plate (34) that faces toward the disk (12) and compensates for an axial run-out of the disk (12) relative to the press plate (34). The resilient ram (40) of the joining tool (10) enables the disk (12) that has an axial run-out to be pressed onto the shaft (14) in a correspondingly sloped manner, with the result that a rotor shaft (16) with a satisfactory bond is made possible.

Claims

1. A joining tool for pressing a disk (12) to a shaft (14), the shaft having opposite first and second ends (18, 24), the joining tool comprising: a press table (22) for receiving the first end (18) of the shaft (14) in a nonrotatable manner; a centering receptacle (26) for receiving the second end (24) of the shaft (14); a press plate (34) for axially pressing the disk (12) onto the shaft (14); and a resilient ram (40) provided on a side of the press plate (34) facing toward the disk (12) for compensating for an axial run-out of the disk (12) relative to the press plate (34).

2. The joining tool of claim 1, wherein the ram (40) has a segmented contact face (44) with contact rings spaced radially from one another and facing toward the disk (12), intermediate spaces being defined between the contact rings for receiving elastically deformed material of the ram (40).

3. The joining tool of claim 1, wherein that the ram (40) is produced from an elastomeric and/or rubber-elastic material selected so that the ram (40) is compressible locally by 0.1 mm≤Δϵ≤10.0 mm in response to a pressing force F of 10 kN≤F≤100 kN.

4. The joining tool of claim 3, wherein the ram (40) is produced from an elastomeric and/or rubber-elastic material selected so that the ram (40) is compressible locally by 0.5 mm≤Δϵ≤5.0 mm in response to a pressing force F of 10 kN≤F≤100 kN.

5. The joining tool of claim 4, wherein the ram (40) is produced from an elastomeric and/or rubber-elastic material selected so that the ram (40) is compressible locally by Δϵ=2.0 mm ±0.2 mm in response to a pressing force F of 10 kN≤F≤100 kN.

6. The joining tool of claim 1, wherein the ram (40) is configured annularly and is spaced radially from the shaft, the ram (40) being dimension to be provided exclusively in a radially outer radius region of the disk (12).

7. The joining tool of claim 1, wherein the centering receptacle (26) is guided axially displaceably in the press plate (34).

8. The joining tool of claim 1, further comprising guide elements that can engage into cavities of the disk (12) for positioning the disk (12) in a circumferential direction relative to the shaft (14), the guide elements being connected to the press plate (34).

9. The joining tool of claim 1, further comprising a force gage for measuring a counterforce that acts on the press plate (34), the force gage being connected to a control device for ending the pressing of the disk (12) onto the shaft (14) in response to a suddenly increasing counterforce and/or in response to an implausible force- displacement profile.

10. A rotor shaft for an electric machine, that can be produced by the joining tool (10) of claim 1, comprising: a shaft (14) having a threading region (28) for threading on disks (12) with radial play and a fastening region (30) offset axially with respect to the threading region (28), the fastening region (30) having radially projecting structural elements (32) for fastening the disks (12); and disks (12), at least one of the disks (12) having an axial run-out, the disks (12) being fastened to the shaft (14) in the fastening region by way of a plastic deformation on the structure elements (32) in a positively locking manner in the circumferential direction and in a non-positive manner in the radial direction by way of a shrink fit and/or force fit.

11. The rotor shaft of claim 10, wherein an intermediate space is configured by the at least one axial run-out of disk (12) and at least one of the disks (12) adjacent to the axial run-out disk (12) in the axial direction.

10. The rotor shaft of claim 10, wherein the structural elements (32) run in a rib-shaped manner in an axial direction of the shaft, the structural elements (32) having radially outer sides and a substantially a conical area that tapers toward the threading region (28).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0023] FIG. 1 is a diagrammatic sectional view of a joining tool.

[0024] FIG. 2 is a diagrammatic perspective view of a rotor shaft that can be produced with the aid of the joining tool of FIG. 1.

DETAILED DESCRIPTION

[0025] FIG. 1 shows a joining tool 10 that can press disks 12 to a shaft 14 to produce a rotor shaft 16 for an electric machine of a motor vehicle, such as a motor vehicle that can be driven electrically. Each disk 12 can have an axial run-out. To this end, the shaft 14 can be inserted at a first end 18 in a receptacle 20 of a press table 22, and can be inserted at an opposite second end 24 in a centering receptacle 26. Thus, the shaft 14 can be positioned fixedly. The disk 12 can be plugged with play on a threading region 28 of the shaft 14. The threading region 28 can be adjoined by a fastening region 30 that has rib-shaped structural elements 32 projecting radially to the outside and running in the axial direction. A press plate 34 is actuated, in particular, hydraulically, to press the disk 12 axially onto the fastening region 30 of the shaft 14. As a result, the structural elements 32 of the shaft 14 dig into the material of the disk 12 on the radially inner edge and produce a bond that is positively locking in the circumferential direction in the manner of a spline system. The press plate 34 can be moved in a linearly parallel manner with respect to a designated rotational axis of the shaft 14 on guide columns 36 that are connected to the press table 22. One or more lubricating devices can be mounted to the press plate 34 near the shaft 30. The lubricating device can apply a lubricant film to the shaft 30 during a return movement of the press plate 34 after pressing the disk 12 onto the shaft 34. A chip detection sensor also may be provided on the press plate 34. The chip detection sensor may operate optically. Detection of a chip that has detached from the shaft 30 and/or from the disk 12 indicates significant damage and an operational malfunction. Thus, the chip detection sensor sends a signal to the control unit either via wires or wirelessly causing an immediate termination of the pressing-on operation.

[0026] The disk 12 has a deliberate or knowingly accepted axial run-off. The end surfaces 38 of the disk 12 can be sloped with respect to a radial plane of the shaft 14. In this regard, the radial plane of the shaft 14 is perpendicular to the rotational axis of the shaft 14. An annular ram 40 produced from a slightly resilient material is provided between the press plate 34 and the disk 12 so that the correct orientation of the radially inner edge of the disk 12 with respect to the shaft 14 is not lost during the pressing-on operation of the disk 12. The ram 40 is dimensioned and disposed to act, to the extent possible, on the outer circumference of the disk 12, possibly via an intermediate ring. The end of the ram 12 that faces toward the press table 22 can be configured to define a segmented contact face 44. The segmented contact face 44 is configured, for example, by way of concentric rings that are spaced apart from one another and, in the sectional view which is shown, define an undulating profile in the radial direction of the side of the ram 40. As a result, the ram 40 can be compressed easily to a more pronounced effect in the one circumferential angle region and to a less pronounced extent in another circumferential angle region thereby compensating for the axial run-off of the disk 12 during the pressing- on operation.

[0027] As is shown in FIG. 2, disks 12 that have a plurality of permanent magnets 42 are produced and can be pressed to the shaft 14 with the aid of the joining tool 10. Adjacent disks 12 can be pressed on in a manner rotated in the circumferential direction with respect to one another. As a result, the permanent magnets 42 that follow one another in the axial direction are arranged offset slightly in the circumferential direction with respect to one another and not exactly behind one another.