EXPANSION CLAMPING DEVICE AND METHOD FOR PRODUCING SAME

Abstract

An expansion clamping device includes a base body and an expansion socket. The expansion socket is inserted into the base body to form a pressure chamber. The pressure chamber can be applied with a hydraulic medium while elastically deforming the expansion socket, in order to achieve a clamping effect in a receiving space which is open in the axial direction of the base body towards a face side and is surrounded by the expansion socket in the circumferential direction. The expansion socket has an elastically deformable clamping section and a collar projecting outwardly in the radial direction on the face side. The expansion socket bears with a bearing surface of the collar in the axial direction against a contact surface of a contact shoulder of the base body and, at least in the region of the bearing surface, is firmly connected, in particular by a material bond, to the base body. The clamping section transitions into the collar in a transition region, a recess being formed in the expansion socket in the transition region in such a way that the transition region overlaps over the contact shoulder of the base body in regions, the bearing surface of the expansion socket bearing against the contact surface in a radially outer contact region thereof, and the contact surface having a radially inner free region adjacent to the contact region, in which free region the expansion socket does not bear against the contact surface.

Claims

1. An expansion clamping device comprising: a base body; and an expansion socket, wherein the expansion socket is inserted into the base body to form a pressure chamber, wherein the pressure chamber is appliable with a hydraulic medium while elastically deforming the expansion socket, in order to achieve a clamping effect in a receiving space which is open in the axial direction of the base body towards a face side and is surrounded by the expansion socket in a circumferential direction, wherein the expansion socket has an elastically deformable clamping section and a collar projecting outwardly in a radial direction on the face side, wherein the expansion socket bears with a bearing surface of the collar in the axial direction against a contact surface of a contact shoulder of the base body and, at least in a region of the bearing surface, is firmly connected to the base body, and wherein the clamping section transitions into the collar in a transition region, a recess being formed in the expansion socket in the transition region in such a way that the transition region overlaps over the contact shoulder of the base body in regions, the bearing surface of the expansion socket bearing against the contact surface in a radially outer contact region thereof, and the contact surface having a radially inner free region adjacent to the contact region, in which free region the expansion socket does not bear against the contact surface.

2. The expansion clamping device according to claim 1, wherein the contact surface in the free region has an elevation preferably spaced from the bearing surface.

3. The expansion clamping device according to claim 2, wherein the elevation is formed as one of a ramp rising radially inwards towards the face side and a protrusion projecting towards the face side.

4. The expansion clamping device according to claim 2, wherein the elevation is arranged at a radially inner end of the free region.

5. The expansion clamping device according to claim 1, wherein the pressure chamber is widened radially inwards in a region of the recess.

6. The expansion clamping device according to claim 1, wherein the recess has, in the axial direction, a first region assigned to the collar and a second region assigned to the clamping section, a width of the recess measured in the radial direction being at least twice as large in the first region as in the second region.

7. The expansion clamping device according to claim 1, wherein the transition region has in longitudinal section a contour which is rounded at least in regions.

8. The expansion clamping device according to claim 7, wherein the contour of the transition region has a constant curvature radius throughout.

9. The expansion clamping device according to claim 7, wherein the contour of the transition region has a first section, which is associated with the collar and extends from the bearing surface and is straight in the axial direction, and a second section, which is associated with the clamping section and is straight in the axial direction, the first section transitioning into the second section via a third section, the third section: a) having a preferably constant curvature radius, or b) is rectilinear in the radial direction, the first section transitioning into the third section via a first curvature radius, and the third section transitioning into the second section via a second curvature radius.

10. The expansion clamping device according to claim 7, wherein the contour of the transition region has a first section associated with the collar and extending from the bearing surface and a second section associated with the clamping section and straight in the axial direction, wherein the first section transitions into the second section via a third section, wherein the first section has a third curvature radius, wherein the third section is rectilinear in the radial direction, and wherein the third section transitions into the second section via a second curvature radius.

11. The expansion clamping device according to claim 1, wherein the expansion socket is soldered to the base body at least in the region of the bearing surface.

12. A method of manufacturing an expansion clamping device, the method comprising: inserting an expansion socket into a base body to form a pressure chamber, the expansion socket having an elastically deformable clamping section and a collar projecting outwardly in the radial direction at the face side, the clamping section transitioning into the collar in a transition region, wherein a recess is formed in the expansion socket in the transition region, wherein: the expansion socket is placed with a contact surface of the collar in an axial direction against a bearing surface of a contact shoulder of the base body, so that the transition region overlaps the contact shoulder of the base body in regions, wherein the bearing surface of the expansion socket is applied to the bearing surface in a radially outer contact region thereof, so that a radially inner free region is formed on the bearing surface adjacent to the contact region, in which free region the expansion socket does not contact the bearing surface, wherein a connecting element is arranged in the free region on the contact surface, and wherein the expansion socket is firmly connected to the base body at least in a region of the bearing surface by a connecting element.

13. The method according to claim 12, wherein the base body, further comprising heating the expansion socket and the connecting element to effect a connection of the expansion socket to the base body by the connecting element.

14. Method according to claim 12, wherein the connecting element is a solder ring.

15. The expansion socket device according to claim 1, wherein the bearing surface of the collar connected to the base body by a material bond.

16. The expansion socket device according to claim 3, wherein the protrusion projects perpendicularly towards the face side.

17. The expansion clamping device according to claim 5, wherein the pressure chamber is widened radially inwards in the region of the recess to at least twice a gap width of a hydraulic gap formed in the clamping section.

18. The expansion socket device according to claim 7, wherein a curvature radius of the contour in the rounded region is at least 0.5 mm.

19. The expansion socket device according to claim 18, wherein the curvature radius of the contour in the rounded region is from at least 0.5 mm to at most 2 mm.

Description

[0058] The invention is explained in more detail below with reference to the drawing. Thereby show:

[0059] FIG. 1 a schematic longitudinal sectional view of a first embodiment of an expansion clamping device;

[0060] FIG. 2 a detailed view of the first embodiment according to FIG. 1;

[0061] FIG. 3 a detailed view of a second embodiment of the expansion clamping device;

[0062] FIG. 4 a detailed view of a third embodiment of the expansion clamping device;

[0063] FIG. 5 a detailed view of a fourth embodiment of the expansion clamping device, and

[0064] FIG. 6 a detailed view of a fifth embodiment of the expansion clamping device.

[0065] FIG. 1 shows a schematic longitudinal sectional view of a first embodiment of an expansion clamping device 1. The expansion clamping device 1 has a base body 3 and an expansion socket 5. The expansion socket 5 is inserted into the base body 3 to form a pressure chamber 7, wherein the pressure chamber 7 can be applied with a hydraulic medium, in particular a hydraulic oil, with elastic deformation of the expansion socket 5, in order to achieve a clamping effect in a receiving space 11 which is open in the axial direction, that is in the direction of a longitudinal axis L of the base body 3, towards a face side 9 and is circumferentially enclosed by the expansion socket 5. The mode of operation of such an expansion clamping device 1, in particular an expansion bushing, is known in principle, so that it will not be discussed in detail here.

[0066] The longitudinal axis L of the base body 3 is at the same time the longitudinal axis L of the expansion socket 5 and at the same time also an axis of symmetry of the expansion socket 5, which is rotationally symmetrical in this respect. It is possible for the base body 3 also to be rotationally symmetrical about the longitudinal axis L.

[0067] In the receiving space 11, a tool shank of a tool not shown here can be received and clamped by means of the expansion socket 5 elastically deformed by hydraulic pressure. In a preferred embodiment, the expansion clamping device 1 itself can be non-rotatably connected to a machine spindle of a machine tool. Alternatively, it is possible for the expansion clamping device 1 itself to be part of such a machine spindle.

[0068] The expansion socket 5 has an elastically deformable clamping section 13 and a collar 15 projecting outwardly in the radial direction at the face side.

[0069] The expansion socket 5 rests with a bearing surface 17 of the collar 15 in axial direction against a contact surface 19 of a bearing shoulder 21 of the base body 3, and at least in the region of the bearing surface 17 is firmly, in particular materially, connected, preferably soldered, preferably brazed, to the base body 3.

[0070] The clamping section 13 transitions into the collar 15 in a transition region 23, a recess 25 being formed in the expansion socket 5 in the transition region 23 in such a way that the transition region 23 engages in regions over the contact shoulder 21 of the base body 3, in particular the contact surface 19. The contact surface 17 is in contact with the bearing surface 19 in a radially outer contact region 27 of the bearing surface 19. The bearing surface 19 has a radially inner free region 29 adjacent to the contact region 27, in which the expansion socket 5, in particular the bearing surface 17, does not bear against the bearing surface 19.

[0071] Thus, in particular, a geometry with low stress and notch effects is provided, whereby advantageously pressure forces formed in the pressure chamber 7 are deflected within the expansion socket 5 in such a way that, when the pressure chamber 7 is pressurized, the contact region 27 is subjected to pressure forces which urge the bearing surface 17 against the contact surface 19 and thereby stabilize the firm, in particular by a material bond connection between the expansion socket 5 and the base body 3. This advantageously increases the compressive strength and fatigue strength of the expansion clamping device 1.

[0072] In particular, as a result of this stabilization, a distance measured in the axial direction between the face side 9 and an axial, face-side end 31 of the pressure chamber 7 can be shortened in comparison with conventional embodiments, so that a tool shank inserted into the receiving space 11 is clamped relatively far forward within the receiving space 11, that is to say toward the face side 9.

[0073] Last but not least, this also stabilizes the connection between the expansion clamping device 1 and the tool.

[0074] FIG. 1 shows schematically that a connecting element 33, in particular a solder ring, can be arranged in the free region 29 on the contact surface 19 in order to connect the expansion socket 5 firmly, in particular materially, to the base body 3 in a simple, cost-effective and reliable manner during the manufacture of the expansion clamping device 1.

[0075] In FIG. 1, a detail of the expansion clamping device 1 is marked A.

[0076] FIG. 2a shows an enlarged representation of this detail A. Identical and functionally identical elements are provided with the same reference signs in all figures, so that in this respect reference is made in each case to the preceding description.

[0077] Particularly preferably, the expansion socket 5 is inserted into the face side of the base body 3. Preferably, the expansion socket 5 is inserted into the base body 3 in such a way that one face side 10 of the expansion socket 5 and the face side 9 of the base body 3 are radially aligned, i.e. at the same axial height. Preferably, the expansion socket 5 has a first outer diameter of an outer peripheral surface 12 of the collar 15 which is smaller than a second outer diameter of an outer peripheral surface 14 of the base body 3 in the region of the face side 9 of the base body 3.

[0078] The contact surface 19 preferably has an elevation 35 in the free region 29. The elevation 35 is formed here as a ramp rising radially inwardly toward the face side 9. The elevation 35 advantageously serves for positioning, preferably also fixing, the connecting element 33, as well as for the process-reliable control of a flow behavior of a connecting material of the connecting element 33 liquefied during the connection of the base body 3 with the expansion socket 5. This flows thereby preferably, in particular by capillary action, into gaps 37 necessarily remaining between the expansion socket 5 and the base body 3 and thus effects the firm, material-locking connection of these parts to one another. The elevation 35 thereby advantageously prevents in particular the flowable connecting material from penetrating into the pressure chamber 7 and in particular into a hydraulic gap 39 of the pressure chamber 7.

[0079] Via the gap 37, which is visually accessible from the face side 9, a quality of the connection can preferably be visually checked by determining by visual inspection whether the connecting material has filled this gap 37. This possibility is made accessible in particular by the fact that flow of the liquefied joining material into undesirable areas is prevented by the elevation 35.

[0080] The gaps 37 are shown exaggeratedly large in FIG. 2 and also in the following figures in order to better illustrate the principle described herein.

[0081] The pressure chamber 7 is preferably widened radially inward in the area of the recess 25, preferably to at least twice the gap width of the hydraulic gap 39.

[0082] The recess 25 preferably has, in the axial direction, a first region 41 associated with the collar 15 and a second region 43 associated with the clamping section 13, a width of the recess 25 measured in the radial direction being at least twice as great in the first region 41, preferably twice as great, as in the second region 43.

[0083] The transition region 23, in particular the recess 25, has a contour 45 in longitudinal section, which is rounded at least in regions. Preferably, a curvature radius of the contour 45 in the rounded region is at least 0.5 mm, preferably from at least 0.5 mm to at most 2 mm, preferably to at most 1.5 mm.

[0084] In the first embodiment example shown here, the contour 45 has a constant curvature radius R throughout.

[0085] FIG. 2b also shows an enlarged representation of the detail marked A in FIG. 1. Preferably, the clamping section 13 has a first partial clamping section 18 and a second partial clamping section 20. In particular, the first partial tensioning section 18 is further away from the face side 10 of the expansion socket 5, as seen in the axial direction, than the second partial tensioning section 20.

[0086] Preferably, the expansion socket 5 has a first wall thickness W1 in the transition region 23 that is different from a second wall thickness W2 that the expansion socket has in the second partial clamping section 20. Preferably, the first wall thickness W1 is measured in the axial direction, with the second wall thickness W2 being measured in the radial direction. Preferably, the first wall thickness W1 is greater than the second wall thickness W2, preferably by a factor of at least 3.6 to at most 4.3.

[0087] Preferably, the expansion socket 5 has a third wall thickness W3 in the region of the collar 15. Preferably, the third wall thickness W3 is a radial extension between an inner circumferential surface 16 of the receiving space 11 and the outer circumferential surface 12 of the collar 15. Preferably, the third wall thickness W3 is half the difference between a first outer diameter of the outer circumferential surface 12 of the collar 15 and an inner diameter of the inner circumferential surface 16 of the receiving space 11. Preferably, the third wall thickness W3 is different from the second wall thickness W2. Preferably, the third wall thickness W3 is greater than the second wall thickness W2, preferably by a factor of from at least 4.2 to at most 4.8 in the embodiment illustrated herein. In another embodiment not illustrated herein, the factor may be from at least 3.3 to at most 3.9.

[0088] Preferably, in the embodiment example shown here, the third wall thickness W3 is greater than the first wall thickness W1. In an embodiment not shown here, the first wall thickness W1 is greater than the third wall thickness W3.

[0089] Preferably, the expansion socket 5 has a fourth wall thickness W4 in the first partial clamping section 18. Preferably, the fourth wall thickness W4 is measured in the radial direction. In particular, the fourth wall thickness W4 is different from the second wall thickness W2. Preferably, the fourth wall thickness W4 is greater than the second wall thickness W2, preferably by a factor of at least 1.6 to at most 2.0.

[0090] Preferably, the first wall thickness W1 is greater than the fourth wall thickness W4. Preferably, the third wall thickness W3 is greater than the fourth wall thickness W4.

[0091] FIG. 3 shows a detailed view of a second embodiment of the Expansion clamping device 1.

[0092] The elevation 35 is here spaced from the bearing surface 17. Furthermore, the elevation 35 is formed here as a protrusion 47 projecting in particular perpendicularly to the face side 9.

[0093] Furthermore, the elevation 35 is arranged at a radially inner end 49 of the free region 29.

[0094] FIG. 4 shows a detailed view of a third embodiment of the expansion clamping device 1. In this third embodiment, the contour 45 has a first section 51, which is associated with the collar 15 and extends from the bearing surface 17 and is straight in the axial direction, and a second section 53, which is associated with the clamping section 13 and is straight in the axial direction, the first section 51 transitioning into the second section 53 via a third section 55.

[0095] The third section 55 here has a constant curvature radius R′.

[0096] FIG. 5 shows a detailed view of a fourth embodiment example of the expansion clamping device 1. Here, too, the contour 45 has the first section 51, the second section 53 and the third section 55, although in contrast to the third embodiment example according to FIG. 4, in the fourth embodiment example according to FIG. 5 the third section 55 is formed in a straight line in the radial direction, the first section 51 transitioning into the third section 55 via a first curvature radius R1, and the third section 55 transitioning into the second section 53 via a second curvature radius R2.

[0097] FIG. 6 shows a detailed view of a fifth embodiment example of the expansion clamping device 1. Here, too, the contour 45 has the first section 51, the second section 53 and the third section 55, although in contrast to the embodiment examples according to FIGS. 4 and 5, in the fifth embodiment example according to FIG. 6 the first section 51 is not formed in a straight line in the axial direction, but rather has a third curvature radius R3 and thus itself transitions directly into the third section 55. This in turn runs in a straight line in the radial direction and transitions into the second section 53 via the second curvature radius R2.

[0098] In the fifth embodiment, the elevation 35 is formed as a ramp rising radially inward toward the face side 9 and is additionally spaced from the bearing surface 17—in the radial direction. Furthermore, the elevation 35 is arranged at the radially inner end 49 of the free region 29.

[0099] The expansion clamping device 1 is preferably manufactured by inserting the expansion socket 5 into the base body 3 to form the pressure chamber 7. In the free region 29, the connecting element 33, preferably a solder ring, in particular in the form of an O-ring, is arranged on the contact surface 19, and the expansion socket 5 is firmly connected, in particular materially connected, to the base body 3, in particular soldered, preferably brazed, by means of the connecting element 33, in particular the solder ring, at least in the region of the bearing surface 17, preferably in the region of the gaps 37.

[0100] For this purpose, the base body 3, the expansion socket 5 and the connecting element 33 are preferably heated, in a particularly preferred embodiment in a furnace.