HYDRAULIC EXPANDING CHUCK

Abstract

A hydraulic expanding chuck having a main body which extends along a rotational axis and has a clamping part for receiving and clamping a shank tool and a shank part having a hollow shank for directly or indirectly coupling the hydraulic expanding chuck to a module of a modular tool system or to a machine spindle. The clamping part has a central receiving opening and, around the receiving opening, at least one pressure chamber to which fluid pressure can be applied and which is separated from the receiving opening via an elastically yielding expansion wall and is connected via a pressure duct to a pressure-generating device situated in the main body. The pressure-generating device is arranged axially in the region between the receiving opening and the hollow shank in a central cut-out, which is coaxial with the receiving opening and which opens into the hollow shank.

Claims

1. A hydraulic expansion chuck comprising a base body, which extends along a rotational axis and which has a clamping part for receiving and clamping a shaft tool, and a shaft part comprising a hollow shaft for directly or indirectly coupling the hydraulic expansion chuck to a module of a modular tool system or to a machine spindle, wherein the clamping part has a central receiving opening and, around the receiving opening, at least one pressure chamber, to which fluid pressure can be applied and which is separated from the receiving opening via an elastically resilient expansion wall and which is connected via a pressure duct to a pressure generating means arranged in the base body, axially in the region between the receiving opening and the hollow shaft, the pressure generating means is arranged in a central recess, which is coaxial to the receiving opening and which leads into the hollow shaft, and can be actuated through the hollow shaft.

2. The hydraulic expansion chuck according to claim 1, wherein the recess is fluidically separated from the receiving opening.

3. The hydraulic expansion chuck according to claim 1, wherein the pressure generating means comprises a piston mechanism comprising a piston, which is arranged in an axially displaceable manner in the central recess, and a screw body, which displaces the piston and which is axially screwed into the base body and can be actuated through the hollow shaft.

4. The hydraulic expansion chuck according to claim 3, wherein the screw body is formed from an adjusting screw, which is screwed into a threaded bore, which axially connects to the recess.

5. The hydraulic expansion chuck according to claim 4, wherein the threaded bore is formed in the shaft part.

6. The hydraulic expansion chuck according to claim 3, wherein a sealing body is assigned to the piston.

7. The hydraulic expansion chuck according to claim 1, wherein the at least one pressure chamber, the pressure duct, and at least a part of the central recess are formed in the clamping part.

8. The hydraulic expansion chuck according to claim 1, wherein the chuck further comprises a ventilation duct connecting the at least one pressure chamber to a ventilation means.

9. The hydraulic expansion chuck according to claim 8, wherein the ventilation means comprising the ventilation duct is arranged in the clamping part.

10. The hydraulic expansion chuck according to claim 9, wherein the ventilation duct and the pressure duct lie offset to one another by 180° with respect to the rotational or longitudinal central axis.

11. The hydraulic expansion chuck according to claim 1, wherein the hollow shaft is formed as a hollow shaft taper.

12. The hydraulic expansion chuck according to claim 1, wherein the clamping part and the shaft part are formed from separately manufactured bodies.

13. The hydraulic expansion chuck according to claim 12, wherein the clamping part and the shaft part are joined together in a positive manner, non-positive manner and/or by means of a substance-to-substance bond.

14. The hydraulic expansion chuck according to claim 12, wherein the clamping part and/or shaft part are/is formed monolithically.

Description

[0020] The invention will be described below on the basis of the enclosed drawings, whereby

[0021] FIG. 1 shows a side view of the hydraulic expansion chuck according to the invention;

[0022] FIG. 2 shows a front-side top view of the hydraulic expansion chuck according to the invention;

[0023] FIG. 3 shows a longitudinal section of the hydraulic expansion chuck according to the invention along a line A-A in FIG. 2; and

[0024] FIG. 4 shows an enlarged view of a region B, which is encircled in FIG. 3, of the hydraulic expansion chuck according to the invention;

[0025] FIGS. 1 to 4 show a preferred embodiment of a hydraulic expansion chuck according to the invention.

[0026] A hydraulic expansion chuck according to the invention has a base body 1, which extends along a rotational or longitudinal central axis 2 and which can be functionally divided into a shaft part 20 and a clamping part 30.

[0027] The shaft part 20 is provided to connect the base body 1 to a (non-illustrated) separating point (within a tool system) or an interface (direct reception in the case of a machine spindle) on a side facing away from the clamping part 30. For such a connection, the shaft part 20 has a hollow shaft 21 as shown in FIG. 3 on the side facing away from the clamping part 30. In the preferred embodiment, the shaft is formed by an HSK shaft, which is known per se to a person of skill in the art.

[0028] As can be seen in FIG. 3, the hollow shaft 21 has a centrally lying hollow space 21a, which is formed essentially rotationally symmetrical to the rotational or longitudinal central axis 2 and which is open towards the side facing away from the clamping part 30. The shaft part 20 furthermore has a central threaded bore 22, which extends along the rotational or longitudinal central axis 2, to which a central recess 32 in the form of a blind hole bore, which extends into the clamping part 30 along the rotational or longitudinal central axis 2, connects towards the clamping part 30.

[0029] A screw body 41 in the form of an adjusting screw, which displaces a piston 42, which will be described in more detail later and which sits in the central recess 32, in the direction of the clamping part 30, is screwed into the threaded bore 22.

[0030] In the preferred embodiment, as can be seen in FIG. 1 and FIG. 3, the shaft part 20 is formed so that, on its front side facing the clamping part 30, it is connected to the clamping part 30.

[0031] The clamping part 30 is provided for receiving and for clamping a (non-illustrated) shaft tool.

[0032] The clamping part 30 has a central receiving opening 31, which extends along the rotational or longitudinal central axis 2 and which is open on the front side facing away from the shaft part 20 and which receives and hydraulically clamps the shaft tool. As shown in FIG. 3, the central receiving opening 31 extends coaxially to the central recess 32 and to the threaded bore 22 in the shaft part 20. FIG. 3 furthermore shows that in the preferred embodiment, the central receiving opening 31 is spaced apart and thus fluidically separated from the central recess 32.

[0033] The above-mentioned central recess 32 or blind hole bore, respectively, extends from the shaft part 20 into the clamping part 30, as can be seen in FIG. 3.

[0034] In the region of the base, a pressure duct 33 leads into the blind hole bore. In the case of the preferred embodiment shown in the figures, the pressure duct 33 runs in an eccentrically curved manner to a pressure chamber assembly. In the preferred embodiment, the pressure chamber assembly comprises two pressure chambers 34, which revolve around the central receiving opening 31 in a ring-shaped manner and which are formed so as to be axially separated from one another and which are fluidically connected to one another via an eccentric connecting duct 36. As shown in FIG. 3, the pressure chambers 34 are in each case separated from the central receiving opening 31 by means of an elastically resilient expansion wall.

[0035] FIG. 3 furthermore shows an eccentric ventilation duct 37, which leads from the pressure chamber 34 to a ventilation means 38. In the preferred embodiment, the ventilation means 38 has a conical screw, which is screwed into a radially running threaded bore 22, comprising a conical front surface, which sits in an accurately fitting manner on a conical seat, in order to tightly seal the ventilation duct 37.

[0036] As can be seen from the different shadings in FIG. 3, the shaft part 20 and clamping part 30 were in each case initially fabricated separately from one another and were subsequently joined together in a rotationally and axially fixed manner in the shown embodiment. Concretely, the clamping part 30, which, with the two pressure chambers 34, the pressure duct 33, the ventilation duct 37, etc., has more complex hollow structures, was fabricated additively by means of 3D printing, while the shaft part 20, which, with the hollow shaft 21, the threaded bore 22, etc., has hollow structures, which can be realized more easily, was manufactures in a conventional manner by means of machining of a metallic body. For a rotationally fixed, axial connection, the clamping part 30 and shaft part 20 were subsequently joined together by means of welding, soldering, or the like by means of a substance-to-substance bond in the preferred embodiment.

[0037] The expansion walls bulge against the shaft tool, e.g. a drill or milling tool, which is received in the central receiving opening 31, during a fluid pressure application of the two pressure chambers 34, whereby the shaft tool is tensioned in a non-positive manner. To unclamp the shaft tool, the fluid pressure in the at least one pressure chamber 34 is decreased.

[0038] For the fluid pressure application of the two pressure chambers 34, the hydraulic expansion chuck according to the invention has a pressure generating means 40, which is described on the basis of FIG. 3 and FIG. 4. In the preferred embodiment, the pressure generating means 40 has a piston 42 mechanism comprising a piston 42, which is arranged in an axially displaceable manner in the central recess 32, and a screw body 41 in the form of an adjusting screw, which displaces the piston 42 and which is screwed into the above-mentioned threaded bore 22 through the hollow shaft 21. A sealing body 43, which sits in the central recess 32 in an accurately fitting manner, made of an elastic material, e.g. rubber or high-strength plastic, which limits a pressure generating chamber, which leads into the pressure duct 33, towards the base of the blind hole bore, is assigned to the piston 42, as is shown in FIG. 3.

[0039] If the adjusting screw is screwed into the threaded bore 22 towards the clamping part 30, the piston 42 is pushed with the sealing body 43 towards the base of the blind hole bore, whereby fluid is displaced from the pressure generating chamber into the pressure duct 33 and into the two pressure chambers 34. The pressure increase generated in the pressure chambers 34 effects a bulging of the expansion walls in the direction of the central receiving opening 31.

[0040] The ventilation means 38 serves for the ventilation of the fluid system after the first or new filling with fluid.

[0041] As shown in FIG. 3, the pressure generating means 40, according to the invention, is arranged axially in the region between the receiving opening 31 and the hollow shaft 21 in the central recess 32, which is coaxial to the receiving opening 31 and which leads into the hollow shaft 21, and can be actuated through the hollow shaft 21. The pressure generating means 40 therefore has a direction of extension, which corresponds to the direction of the rotational or longitudinal central axis 2. By means of the central arrangement according to the invention of the pressure generating means 40, an imbalance of the hydraulic expansion chuck, which is caused by the pressure generating means 40, can be reduced significantly, because a more even mass distribution around the rotational or longitudinal central axis 2 of the hydraulic expansion chuck can be attained due to the central arrangement according to the invention, in the case of which the main axes of inertia, respectively, of the base body 1 and of the pressure generating means 40 lie at least in the vicinity of the rotational or longitudinal central axis 2. By means of the axial extension of the pressure generating means 40, the radial expansion of the base body 1 can furthermore be kept small. According to the invention, the pressure generating means 40 can furthermore be actuated through the hollow shaft 21. The pressure generating means 40 can be accessed through the open hollow shaft 21 of the shaft part 20, which faces away from the clamping part 30.

[0042] Deviations from the above-described embodiment are possible within the scope of protection of the claims.

[0043] Instead of the two concentrically running pressure chambers 34 shown in FIG. 3, e.g., one, three, four, or more annularly concentrically running pressure chamber(s) can thus be present, or the pressure chambers can in each case be formed to be only partially circumferential.

[0044] The base body 1 as a whole can furthermore be manufactured monolithically.

[0045] The at least one pressure chamber 34 can be realized via a pivot bearing, which is axially inserted into the central receiving opening 31, as it is known, e.g., from DE 102012215036 A1.

[0046] Instead of a HSK shaft, the shaft part 20 can furthermore have, e.g., a steep taper shaft (SK), cylinder shaft, or another hollow shaft, which is likewise known to the person of skill in the art.

[0047] 1 base body (hydraulic expansion chuck)

[0048] 20 shaft part

[0049] 21 hollow shaft

[0050] 21a hollow space

[0051] 22 threaded bore

[0052] 30 clamping part

[0053] 31 receiving opening

[0054] 32 central recess

[0055] 33 pressure duct

[0056] 34 pressure chambers

[0057] 36 connecting duct

[0058] 37 ventilation duct

[0059] 38 ventilation means

[0060] 40 pressure generating means

[0061] 41 screw body

[0062] 42 piston

[0063] 43 sealing body