Sintered Part and Method for Producing Same

Abstract

A sintered part has at least one base with a first end face which faces in a first axial direction and a second end face which faces in a second axial direction. The end faces are produced in a press for producing a green body (which is subsequently sintered to form the sintered part) by applying at least one punch which can be moved along the axial directions. The sintered part has an elevation extending from the first end face towards one end at least in the axial direction over a first height, and the elevation has a first width extending transversely to the axial direction in a radial direction and at least some portions of which are smaller than 0.8 millimeters, wherein at least some portions of the sintered part have a first density along the first width, said density equaling at least 87% of the full material density.

Claims

1. A sintered part of a metallic material, produced by pressing a powdered metallic material to form a green compact and by subsequent sintering, wherein the sintered part comprises at least one base with a first end face facing in a first axial direction and a second end face facing in a second axial direction, which are produced in a press for producing the green compact by applying at least one punch that is moveable in the axial directions; wherein the sintered part has an elevation extending over a first height from the first end face to one end at least in the axial direction, wherein the elevation has a first width extending in a radial direction and transversely to the axial direction that is at least partially less than 0.8 millimeters, wherein, along the first width, the sintered part at least partially has a first density which is at least 85% of a full density of the material.

2. The sintered part as claimed in claim 1, wherein the first density along the first width is at least partially at least 92% of the full density of the material.

3. The sintered part as claimed in claim 1, wherein the first width is at least partially less than 0.3 millimeters.

4. The sintered part as claimed in claim 1, at least having a second height which extends in the axial direction between the second end face and the end, wherein, in the axial direction between the first end face and the end, the elevation has a maximum second width extending in the radial direction, wherein the second width is at most 1.0 millimeter, wherein the first height is at least 5% of the second height.

5. The sintered part as claimed in claim 1, wherein at least one side surface of the elevation runs at least partially inclined at an angle of at most 30 angular degrees with respect to the axial direction.

6. The sintered part as claimed in claim 1, wherein the elevation extends in a peripheral direction, extending transversely to the axial direction, along the first end face in the form of a ring or a segment of a ring.

7. The sintered part as claimed in claim 1, wherein at least the elevation has multiple regions with differing densities in a cross section.

8. The sintered part as claimed in claim 1, wherein the end is processed exclusively by shaping at least after the sintering, wherein the sintered part has a third end face which extends parallel to the radial direction.

9. The sintered part as claimed in claim 1, wherein at least the elevation at least partially consists of a magnetic material.

10. A method for producing a calibrated sintered part as claimed in claim 1, wherein the method comprises at least the following steps: a) providing a sintered part, wherein the sintered part has at least one base with a first end face facing in a first axial direction and a second end face facing in a second axial direction and also an elevation extending over a first height from the first end face to one end at least in the axial direction, wherein the elevation forms a third end face at the end; b) arranging the sintered part in a tool; c) using the tool to subject the sintered part to a first compressive force acting on the end faces at least in the axial direction; d) subjecting the sintered part to a second compressive force acting at least on part of the elevation at least in a radial direction, wherein the sintered part is shaped at least by the second compressive force, wherein steps c) and d) are carried out at least partially at the same time and the sintered part is a calibrated sintered part after steps c) and d).

11. The method as claimed in claim 10, wherein the sintered part is also at least partially shaped by the first compressive force.

12. The method as claimed in claim 10, wherein the first compressive force is applied to the sintered part at least over the entire first end face, the entire second end face and the entire third end face.

13. The method as claimed in claim 10, wherein the second compressive force is applied to the sintered part via at least one rolling tool or via a slide that is moveable at least in the radial direction.

14. The method as claimed in claim 10, wherein the sintered part is pressed quasi-isostatically by the first compressive force and the second compressive force.

15. A sintered part produced by a method as claimed in claim 10, wherein an elevation of the sintered part consists at least partially of a magnetic material, for a device utilizing magnetic forces, wherein the elevation is used to influence a magnetic flux density.

Description

[0095] The invention and the technical field will be explained in more detail below on the basis of the appended figures. It is to be noted that the invention is not intended to be limited by the exemplary embodiment variants mentioned. In particular, unless explicitly stated otherwise, it is also possible to extract partial aspects of the explanatory substantive matter illustrated in the figures and to combine these with other constituent parts and findings from the present description. In particular, it is to be noted that the figures and in particular the size ratios illustrated are only schematic. In the figures:

[0096] FIG. 1: shows a side view in section of a part of a first embodiment variant of a device utilizing magnetic forces;

[0097] FIG. 2: shows a side view in section of a part of a second embodiment variant of a device utilizing magnetic forces;

[0098] FIG. 3: shows a side view in section of a third embodiment variant of a device utilizing magnetic forces;

[0099] FIG. 4: shows a side view in section of a press and a green compact;

[0100] FIG. 5: shows a side view in section of an elevation of a sintered part; and

[0101] FIG. 6: shows a perspective view in section of a tool.

[0102] FIG. 1 shows a side view in section of a part of a first embodiment variant of a device 30 utilizing magnetic forces. The device 30 is an actuator, in which a body 42 of the device 30 is displaceable with respect to a housing 40 of the device 30 in an axial direction 4, 6 and along the axis 45 for the purpose of actuating a component. The device 30 is substantially rotationally symmetrical in relation to the axis 45. The displacement of the body 42 can be achieved by subjecting the body 42 to a magnetic field, it being possible to generate the magnetic field e.g. by means of a coil 41 which is exposed to an electric current.

[0103] The housing 40 comprises a sintered part 1 of a metallic material. The sintered part 1 is produced by pressing a powdered metallic material to form a green compact 2 (see FIG. 4) and by subsequent sintering. The sintered part 1 has a base 3 with a first end face 5 facing in a first axial direction 4 and a second end face 7 facing in a second axial direction 6, which are produced in a press 8 (see FIG. 4) for producing the green compact 2 by applying at least one punch 9 (see FIG. 4) that can be moved in the axial directions 4, 6. The sintered part 1 has an elevation 12 extending over a first height 11 from the first end face 5 to one end 10 at least in the axial direction 4, 6.

[0104] In FIG. 1, the housing 40, the body 42 and the sintered part 1 are components produced conventionally by sintering technology. This figure illustrates regions of different densities, in particular regions with a greatest density 44 and areas with a lowest density 43. On account of the special geometry of the elevation 12, this region has a lowest density 43.

[0105] FIG. 2 shows a side view in section of a part of a second embodiment variant of a device 30 utilizing magnetic forces. FIG. 3 shows a side view in section of a third embodiment variant of a device 30 utilizing magnetic forces. FIGS. 2 and 3 will be described jointly below. Reference is made to the statements relating to FIG. 1.

[0106] The sintered part 1 has a base 3 with a first end face 5 facing in a first axial direction 4 and a second end face 7 facing in a second axial direction 6, which are produced in a press 8 (see FIG. 4) for producing the green compact 2 by applying at least one punch 9 (see FIG. 4) that can be moved in the axial directions 4, 6. The sintered part 1 has an elevation 12 extending over a first height 11 from the first end face 5 to one end 10 at least in the axial direction 4, 6.

[0107] The elevation 12 has a first width 14 extending in a radial direction 13 and transversely to the axial direction 4, 6. Along the first width 14, the sintered part 1 at least partially has a first density 15.

[0108] The sintered part 1 is produced by a follow-up pressing operation, what is referred to as calibration, after the sintering, which is used to obtain a greater degree of dimensional accuracy or an at least locally higher density.

[0109] The base 3 of the sintered part 1 comprises a disk-shaped part of the sintered part 1, from which the elevation 12 extends in the axial direction 4, 6.

[0110] The sintered part 1 has a second height 16 that extends in the axial direction 4, 6 between the second end face 7 and the end 10. In the axial direction 4, 6 between the first end face 5 and the end 10, the elevation 12 has a maximum second width 17 extending in the radial direction 13.

[0111] A side surface 18 of the elevation 12 runs inclined at an angle 48 with respect to the axial direction 4, 6.

[0112] The elevation 12 extends transversely to the radial direction 13 and transversely to the axial direction 4, 6 in a peripheral direction 19. The elevation 12 has a further side surface which is opposite to the side surface 18, each of which extends from the first end face 5 to the end 10 and in the peripheral direction 19 extending transversely to the radial direction 13 and transversely to the axial direction 4, 6.

[0113] The elevation 12 extends in the form of a ring in the peripheral direction 19 along the first end face 5. The extent 12 in the form of a ring forms an elevation 12 around the full periphery.

[0114] The device 30 is an actuator, in which a body 42 of the device 30 is displaceable with respect to a housing 40 of the device 30 in an axial direction 4, 6 and along the axis 45 for the purpose of actuating a component. The device 30 is substantially rotationally symmetrical in relation to the axis 45. The displacement of the body 42 can be achieved by subjecting the body 42 to a magnetic field, it being possible to generate the magnetic field e.g. by means of a coil 41 which is exposed to an electric current. When the electric current is switched off, the body 42 is displaced back in the first axial direction 4 via the spring 48.

[0115] The elevation 12 makes it possible to improve the magnetic flux density. The conical shape of the elevation 12 toward the end 10 enables the field lines 39 of the magnetic field to be effectively coupled into the body 42.

[0116] FIG. 4 shows a side view in section of a press 8 and a green compact 2. Reference is made to the statements relating to FIGS. 1 to 3.

[0117] The sintered part 1 illustrated in FIGS. 1 to 3 and 5 is produced from a powdered material by pressing to form a green compact 2 and subsequently by sintering to form a solid workpiece (the sintered part 1).

[0118] Punches 9 that can be moved in the axial direction 4, 6 are applied to the end faces 5, 7. The powdered material is arranged in the press 8, in this instance in a receptacle 32, formed by a lower punch 9 and a die 46, of the press 8. In this respect, it is precisely in the region of the elevation 12 that only a low density can be obtained.

[0119] This region of the elevation 12 is further compacted and further shaped in particular during calibration in a calibrating tool 25.

[0120] FIG. 5 shows a side view in section of an elevation 12 of a sintered part 1 (e.g. a sintered part according to FIGS. 2 and 3). Reference is made to the statements relating to FIGS. 1 to 4.

[0121] The sintered part 1 has an elevation 12 extending over a first height 11 from the first end face 5 to one end 10 at least in the axial direction 4, 6. The elevation 12 has a first width 14 extending in a radial direction 13 and transversely to the axial direction 4, 6. Along the first width 14 and along the first height 11, the sintered part 1 has a first density 15. The elevation 12 has multiple regions 21, 22, 23 with differing first densities 15 in the cross section 20. The first region 21 has the highest density 44 of the first densities 15. The third region 23 has the lowest density 43 of the first densities 15. The first density 15 of the second region 22 lies between the values of the highest density 44 and the lowest density 43.

[0122] A selective further compaction of the sintered part 1 can also be used to locally set a density, with the result that high and possibly different densities can be provided. A density setting or density distribution of this kind in a sintered part 1 of magnetic material can be especially advantageous specifically for devices 30 utilizing magnetic forces.

[0123] It can be seen in FIG. 5 that the end 10 was shaped as a result of the further compaction of the side surface 18 and a projection extending in the axial direction 4, 6 has formed in the process. A deformation of this kind can be prevented by using a first compressive force 26 to support specifically the third end face 24 with respect to the axial direction 4, 6 (see FIG. 6). By subjecting the sintered part 1 to a first compressive force 26 and a second compressive force 27 at the same time, it is possible on the one hand to achieve further compaction and on the other hand to realize a predetermined geometry of the further-compacted sintered part.

[0124] FIG. 6 shows a side view in section of a tool 25. Reference is made to the statements relating to FIG. 1 to.

[0125] The tool 25 comprises a receptacle 32, in which the sintered part 1 is arranged for further processing. The tool 25 also comprises an upper punching unit having a punch 9 above the receptacle 32 and a lower punching unit having punches 9 below the receptacle 32 for the purpose of subjecting the sintered part 1 arranged in the receptacle 32 to the first compressive force 26. The lower punching unit has a mandrel 47 which extends through the sintered part 1 and into the punch 9 of the upper punching unit. In this instance, the receptacle 32 is formed by way of the punching units or the punches 9 and the mandrel 47. Furthermore, two rolling tools 28, consisting of a roller 37 and a roller carrier 36, are provided for subjecting the sintered part 1 arranged in the receptacle 32 to the second compressive force 27.

[0126] Instead of the rolling tools 28, it is also possible to provide slides 29 (only indicated here), which are advanced with respect to the sintered part 1 only in the radial direction 13.

[0127] The rolling tools 28 are arranged in a radial direction 13 next to the receptacle 32 for the sintered part 1. The rolling tools 28 are arranged such that they can rotate with respect to the sintered part 1 and the punches 9 and are able to rotate together around the sintered part 1 in the peripheral direction 19. For this purpose, the rolling tools 28 are arranged in a rotatable first tool part 34 which is mounted rotatably with respect to a stationary second tool part 35 via bearings (not illustrated here).

[0128] Each rolling tool 28 comprises a roller 37, which is guided at least or exclusively in a peripheral direction 19 along the peripheral surface 31 of the sintered part 1. The second compressive force 27 is applied to the sintered part 1 via the roller 37. The roller 37 rolls on the sintered part 1 in the process. The outer peripheral surface of the roller 37 of the rolling tool 28 has a specific shape, with the result that this specific shape is transferred to the sintered part 1 via the rolling tool 28 in the course of the rolling operation. The roller 37 has a shoulder 38 which also supports the sintered part 1 or the end 10 of the sintered part 1 and the third end face 24 with respect to the axial direction 4, 6.

[0129] The sintered part 1 has a first end face 5, a second end face 7 spaced apart in an axial direction 4, 6, and a peripheral face 31 between the end faces 5, 7.

[0130] The tool 25 comprises a control unit 33 suitably designed (equipped, configured or programmed) to control the tool 25 for carrying out the method, with the control unit 33 being able to control the punch 9 and the mandrel 47, and therefore the first compressive force 26, and additionally the rolling tools 28 and the first tool part 34, and therefore the second compressive force 27, at least intermittently at the same time.

LIST OF REFERENCE SIGNS

[0131] 1 Sintered part [0132] 2 Green compact [0133] 3 Base [0134] 4 First axial direction [0135] 5 First end face [0136] 6 Second axial direction [0137] 7 Second end face [0138] 8 Press [0139] 9 Punch [0140] 10 End [0141] 11 First height [0142] 12 Elevation [0143] 13 Radial direction [0144] 14 First width [0145] 15 First density [0146] 16 Second height [0147] 17 Second width [0148] 18 Side surface [0149] 19 Peripheral direction [0150] 20 Cross section [0151] 21 First region [0152] 22 Second region [0153] 23 Third region [0154] 24 Third end face [0155] 25 Tool [0156] 26 First compressive force [0157] 27 Second compressive force [0158] 28 Rolling tool [0159] 29 Slide [0160] 30 Device [0161] 31 Peripheral surface [0162] 32 Receptacle [0163] 33 Control unit [0164] 34 First tool part [0165] 35 Second tool part [0166] 36 Roller carrier [0167] 37 Roller [0168] 38 Shoulder [0169] 39 Field line [0170] 40 Housing [0171] 41 Coil [0172] 42 Body [0173] 43 Lowest density [0174] 44 Highest density [0175] 45 Axis [0176] 46 Die [0177] 47 Mandrel [0178] 48 Spring