Method of firmly connecting a shaft to a rotor-housing part, and rotor-housing part

Abstract

In a method for firmly connecting a shaft to a rotor-housing part, the rotor-housing part is provided having a bearing flange and the shaft is provided having a recess, extending in the circumferential direction of the shaft, on an outer circumference of the shaft. The shaft is inserted into the bearing flange such that the recess and the bearing flange overlap one another. Material of the bearing flange is introduced into the recess. With the connection, created in this way, between the shaft and bearing flange, a high press-out force is achieved.

Claims

1. A rotor-housing part, comprising: a bearing flange, and a shaft having a recess on an outer circumference of the shaft, the recess extending in a circumferential direction about a longitudinal axis of the shaft, wherein the shaft is inserted in the bearing flange, wherein material of the bearing flange engages in the recess such that the shaft is connected to the bearing flange, wherein a press-out force of the shaft in at least one press-out direction is at least 5 kN at a temperature of 23° C.

2. The rotor-housing part according to claim 1, further comprising a bead on the bearing flange.

3. The rotor-housing part according to claim 2, wherein the bead is either a full bead, or a half bead.

4. The rotor-housing part according to claim 2, wherein the bead extends around an entire circumference, in a circumferential direction, of the bearing flange.

5. The rotor-housing part according to claim 1, wherein the recess extends around an entire circumference, in a circumferential direction, of the shaft.

6. The rotor-housing part according to claim 1, wherein the shaft is oversize relative to the bearing flange, and the shaft is pressed into the bearing flange with an interference fit.

7. The rotor-housing part according to claim 1, further comprising a rotor-housing part formed from sheet-metal, wherein a bottom portion of the formed sheet-metal is punched and plunged to produce the bearing flange.

8. The rotor-housing part according to claim 1, wherein at least 30% of the recess is filled with a material of the bearing flange.

9. The rotor-housing part according to claim 1, wherein at least 50% of the recess is filled with a material of the bearing flange.

10. The rotor-housing part according to claim 1, wherein an axial length of the bearing flange is less than half an axial length of the shaft.

11. The rotor-housing part according to claim 1, wherein the press-out force of the shaft in the at least one press-out direction is at least 7 kN at a temperature of 23° C.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Exemplary embodiments of the invention are described in more detail in the following text with reference to the drawing, in which:

(2) FIG. 1 shows a section through a rotor-housing part according to one stage of a method for firmly connecting a shaft to the rotor-housing part;

(3) FIG. 2 shows a perspective view of a shaft that is intended to be connected to the rotor-housing part in FIG. 1;

(4) FIG. 3 shows a section corresponding to FIG. 1, wherein the shaft has been inserted into a bearing flange of the rotor-housing part in a further stage of the method;

(5) FIG. 4 shows a section corresponding to FIGS. 1 and 3, in a further stage of the method for firmly connecting the shaft to the rotor-housing part;

(6) FIG. 5 shows a plan view of a roller burnishing tool that can be used in the method for firmly connecting the shaft to the rotor-housing part;

(7) FIG. 6 shows a side view of the tool in FIG. 5; and

(8) FIG. 7 shows an enlarged detail from FIG. 6.

EMBODIMENTS

(9) FIG. 1 shows a rotor-housing part 10, to which a shaft 12, shown in FIG. 2, is intended to be firmly connected. The rotor-housing part 10 is formed in a rotationally symmetric manner with respect to an axis 14. The rotor-housing part 10 according to FIG. 1 may have been manufactured in particular by sheet-metal forming from a metal blank, for example a steel or aluminium blank. The rotor-housing part 10 has a bottom 16 and a wall 18, extending away from the bottom 16, which wall extends over the full circumference about the axis 14.

(10) The pot-shaped rotor-housing part 10 may be produced for example by deep drawing from a metal blank.

(11) The rotor-housing part 10 also has a bearing flange 20, which is configured in the form of a collar at the bottom 16 of the rotor-housing part 10 integrally or in one piece with the bottom 16. The bearing flange 20 may be formed by punching and plunging a bottom portion of the bottom 16.

(12) The shaft 12 is in the form of a peg 22. The shaft 12 has a recess 24, extending in the circumferential direction of the shaft 12, on an outer circumference of the shaft 12. The recess 24 is configured in the form of a relief groove or slot and may have a depth of about 0.3 mm to 1 mm and an axial width of about 1 mm. The pin 22 may have a diameter of about 1 cm. The shaft 12 has a much greater length than the bearing flange 20, and specifically, in the exemplary embodiment shown, a length that is more than five times greater. The length of the bearing flange 20 may be about 1 cm or somewhat less.

(13) After the rotor-housing part 10 has been provided, according to FIG. 3, the shaft 12 is inserted into the bearing flange 20. The shaft 12 is inserted into the bearing flange 20 such that the recess 24 of the shaft 12 and the bearing flange 20 overlap. In the exemplary embodiment shown here, the shaft 12 is inserted such that the recess 24 is located inside one end 26 of the bearing flange 20.

(14) The shaft 12 may be provided having an oversize with respect to the clear width of the opening 28 in the bearing flange. In this case, the shaft 12 is pressed into the bearing flange 20. With such an interference fit of the shaft 12 in the bearing flange 20, it is possible to achieve press-out forces that may sometimes be too low. In FIG. 3, arrows F.sub.1 and F.sub.2 indicate forces that act axially on the shaft 12 and, when they overcome the resistance to shifting provided by the interference fit, can result in axial shifting of the shaft 12 relative to the bearing flange 20, this being intended to be avoided, however. A force that overcomes the resistance to shifting is referred to as a press-out force.

(15) In order to achieve a higher press-out force than is achieved by an interference fit, in the method for firmly connecting the shaft 12 to the rotor-housing part 10, material of the bearing flange 20 is introduced, in a further step, into the recess 24 of the shaft 12. This is indicated in FIG. 4 by arrows 30.

(16) As a result of material of the bearing flange 20 being introduced into the recess 24 of the shaft 12, the press-out force that causes the shaft 12 to shift in an axial direction relative to the bearing flange 20 is considerably increased. As a result, press-out forces of 5 kN or even above 7 kN can be achieved, this not being achievable with an interference fit in such a short bearing flange 20 alone.

(17) The introduction of material of the bearing flange 20 into the recess 24 can be accomplished in that a bead 32 in the form of a full or half bead is formed in the bearing flange 20 from an outer side of the bearing flange 20. In the exemplary embodiment shown in FIG. 4, a half bead is introduced into the bearing flange 20. A half bead is appropriate here given the very short axial length of the bearing flange 20. If the bearing flange 20 has a greater axial length, the shaft 12 can be inserted into the bearing flange such that the recess 24 is not located at the end 26 of the bearing flange 20, as is shown in FIG. 3, but is located more deeply in the bearing flange 20. In this case, provision can also be made to form a full bead in the bearing flange 20, in order in this way to introduce material of the bearing flange 20 into the recess 24.

(18) The introduction of material of the bearing flange 20 into the recess 24 is preferably carried out by means of a roller burnishing tool, wherein such a roller burnishing tool will be described in more detail below. In other exemplary embodiments, the material of the bearing flange 20 can be introduced into the recess 24 by means of a slider, a forming tool, a pressing tool or plier tool. Material of the bearing flange 20 can also be introduced into the recess 24 only in portions or only around part of the circumference in the circumferential direction of the recess, provided that the desired press-out force is achieved. Irrespective thereof, the recess 24 can extend over the full circumference around the shaft 12, and likewise, the bead 32 can extend over the full circumference around the bearing flange 20 in the circumferential direction thereof.

(19) During the introduction of material of the bearing flange 20 into the recess 24, the latter does not have to be completely filled with the material of the bearing flange 20. Depending on the press-out force to be achieved, 30% to 50% filling of the recess 24 with the material of the bearing flange 20 may be enough in order to achieve the requisite press-out force. A higher degree of filling increases the press-out force.

(20) FIG. 4 shows the rotor-housing part 10 with the firmly mounted shaft 12. The shaft 12 is fixed to the rotor-housing part 10 so as to be immovable both in the direction of the axis 14 and in the direction of rotation about the axis 14, and exhibits high resistance to shifting relative to the bearing flange 20.

(21) The rotor-housing part 10 can be part of a rotor of an electric motor (not illustrated in more detail), for example of an electric motor of a fan, as can be used in a motor vehicle as part of the engine cooling system.

(22) FIGS. 5 and 6 show a roller burnishing tool 40 that can be used in the method step according to FIG. 4 in order to introduce material of the bearing flange 20 into the recess 24 of the shaft 12. By way of the roller burnishing tool 40, in particular the bead 32, in this case in the form of a half bead, can be formed in the bearing flange 20 from the outer side thereof.

(23) The roller burnishing tool 40 has a main body 42, which on one side is connected to a drive shaft 46 and on the other side bears three rollers 44a, 44b and 44c. The rollers 44a, 44b, 44c are mounted in a rotatable manner on the main body 42, as is indicated by an arrow 48 for the roller 44a.

(24) The rollers 44a, 44b, 44c are spaced apart from one another to such an extent that they can be fitted over the shaft 12 from one side 50 in FIG. 4, until the roller burnishing faces 52 of the rollers 44a, 44b, 44c are arranged at the level of the recess 24 of the shaft 12 and can come into engagement with the bearing flange 20 on the outer side thereof. As a result of the main body 42 being rotated via the drive shaft 46, the outer side of the bearing flange 20 is roller burnished in the region of its end 26 by means of the rollers 44a, 44b, 44c until the bead 32 has been formed and the amount of material of the bearing flange 20 that is required for the press-out force to be achieved has been introduced into the recess 24.

(25) FIG. 7 shows, in an enlarged detail, the roller burnishing face 52 of the roller 44a, the shaping of which is particularly suitable for forming a half bead. In this case, the roller burnishing face 52 is slightly indented radially. If a full bead is intended to be roller burnished, a roller burnishing face is suitable that protrudes radially outwards from the rest of the body of the roller (not illustrated).