Hydraulic expansion chuck for receiving a tool

Abstract

A hydraulic expansion chuck (1) for receiving a cutting tool, having a chuck main body (2, 3) with a connection part (3) for fastening to a machine tool and having a clamping part (2) for clamping the cutting tool in a center receiving opening (4), wherein the clamping tool (2) comprises at the receiving opening (4) at least one first expansion chamber (5) and radially spaced therefrom a second expansion chamber (6).

Description

[0001] Hydraulic expansion chuck for holding a tool

[0002] The invention relates to a hydraulic expansion chuck for holding a cutting tool.

[0003] The use of hydraulic chucks is widespread. Conventional hydraulic chucks are a one-piece construction, featuring a section with internal chambers for clamping a tool, as well as a section for the machine-side connection.

[0004] To clamp the tool, a fluid is introduced into chambers that fill and expand when pressure is applied. The expansion of these chambers clamps the tool inserted into the hydraulic chuck. Hydraulic chucks clamp a tool when an expansion chamber bulges toward the inserted tool, exerting a clamping force.

[0005] In the prior art, for example, DE 10 2015 120 971 A1 describes a hydraulic expansion chuck for holding and clamping cutting tools. This comprises a chuck body with a separate clamping bush, at the front end of which the shank of a cutting tool is clamped. Arranged within the wall of the front part are axially spaced chambers into which a fluid is admitted under pressure to bulge the chambers outward.

[0006] A disadvantage of these known hydraulic expansion chucks is that the optimal clamping of a shank of a cutting tool is not always guaranteed; in particular, due to the nature of the expansion chambers, the level of the generated clamping forces is limited.

[0007] It is the object of the present invention to provide a hydraulic expansion chuck which overcomes the disadvantages of the prior art and which is suitable for optimally clamping the shank of a cutting tool.

[0008] The invention comprises a hydraulic expansion chuck for holding a cutting tool, comprising a chuck base body with a connecting part for attachment to a machine tool and a clamping part for clamping the cutting tool in a central receiving opening. The clamping part comprises at least one first expansion chamber at the receiving opening and a second expansion chamber radially spaced therefrom. It has been shown that, due to the two expansion chambers located at a radial distance from each other, the clamping forces generated can be increased, allowing the cutting tool to be clamped securely and optimally.

[0009] According to an advantageous aspect, the first expansion chamber comprises at least two separate sub-chambers located at the same radial distance from the center axis of the hydraulic expansion chuck. The at least two separate sub-chambers are preferably located symmetrically on a common circle around the center axis of the hydraulic expansion chuck.

[0010] Particularly preferably, the first expansion chamber comprises exactly three separate subchambers. Each of the three subchambers can be interrupted by an intermediate recess open toward the center.

[0011] Advantageously, the three sub-chambers have identical sizes and geometries. The sub-chambers are arranged rotationally symmetrically (triple symmetry) on a common circle. Advantageously, the second expansion chamber is annular. The second expansion chamber can be designed as a continuous full circle (solid cylinder) enclosing the sub-chambers of the first expansion chamber.

[0012] Advantageously, the second expansion chamber comprises two chamber rings connected in the axial direction by a connecting channel.

[0013] The first expansion chamber and the second expansion chamber are advantageously fluidically connected to each other via a chamber channel. This allows the pressure on the fluid in both expansion chambers to be increased via a common unit.

[0014] Preferably, each sub-chamber of the first expansion chamber and the second expansion chamber are connected (to each other) via a separate chamber channel.

[0015] An advantageous aspect provides that each subchamber of the first expansion chamber and the second expansion chamber are connected via three separate chamber channels. This ensures a homogeneous pressure distribution.

[0016] Particularly preferably, the hydraulic expansion chuck further comprises an actuating unit for pressurizing a fluid, wherein the actuating unit is connected to the first expansion chamber via a connecting channel. A simple solution is a fluid-filled cavity (threaded bore) into which a screw can be screwed to reduce the volume of the fluid contained in the cavity by actuating the screw.

[0017] Advantageously, the receiving opening comprises three slotted openings spaced at an angle of 120°. A partial chamber is arranged between each two slotted openings.

[0018] The invention is explained in more detail below with reference to the examples shown in the accompanying drawings. Identical reference numerals refer to the same features in all figures.

[0019] They show:

[0020] Fig. 1 is a sectional view from the side of the hydraulic chuck for receiving a cutting tool according to an embodiment of the invention; Fig. 2 is a partial sectional view of a first variant with three sub-chambers of the first expansion chamber of the hydraulic chuck from Fig. 1; and

[0021] Fig. 3 is a partial sectional view of a second variant with three sub-chambers of the first expansion chamber of the hydraulic expansion chuck from Fig. 1.

[0022] Fig. 1 shows a side sectional view of the side of the hydraulic expansion chuck 1 for receiving a cutting tool (not shown) according to an embodiment of the invention.

[0023] The hydraulic expansion chuck 1 has a chuck base body 2, 3 with a connecting part 3 for attachment to a machine tool (not shown) and with a clamping part 2 for clamping the (shank of a) cutting tool (not shown) in a central receiving opening 4. The clamping part 2 comprises at least one first expansion chamber 5 at the receiving opening 4 and a second expansion chamber 6 radially spaced (outside) therefrom.

[0024] The second expansion chamber 6 is annular and completely encloses the first expansion chamber 5 on the outside.

[0025] The second expansion chamber 6 comprises two chamber rings 61 connected in the axial direction by a connecting channel 63. The chamber rings have a cross-section that is larger than the connecting channel.

[0026] The hydraulic expansion chuck 1 comprises an actuating unit 7 for pressurizing a fluid (hydraulic oil) filled into the expansion chambers. In the example shown, the actuating unit 7 is connected to the first expansion chamber 5 via a connecting channel 71.

[0027] Fig. 2 shows a partial sectional view of a first variant of the hydraulic expansion chuck 1 from Fig. 1, with three partial chambers of the first expansion chamber 5.

[0028] In the example shown, the first expansion chamber 5 has exactly three separate sub-chambers 51, 52, 53. The separate sub-chambers 51, 52, 53 are located at the same radial distance from the center axis of the hydraulic expansion chuck 1. The three sub-chambers 51, 52, 53 have an identical size and geometry in this example.

[0029] The first expansion chamber 5 and the second expansion chamber 6 are fluidically connected to each other via a chamber channel 8. Each sub-chamber 51, 52, 53 is connected to the second expansion chamber 6 via a single separate chamber channel 8.

[0030] The second expansion chamber 6 is, as can be clearly seen in this view, annular in shape, unlike in Fig. 1.

[0031] Fig. 3 shows a partial sectional view of a second variant of the hydraulic expansion chuck 1 from Fig. 1.

[0032] In this example, the first expansion chamber 5 again comprises three sub-chambers 51, 52, 53.

[0033] Each sub-chamber 51, 52, 53 of the first expansion chamber 5 is connected to the second expansion chamber 6 via three separate chamber channels 8. The receiving opening 4 comprises three slotted openings 41, each spaced at an angle of 120° and open toward the center.

[0034] There is a partial chamber 51, 52, 53 between each two slot openings 41.

Claims

Claims 1. Hydraulic expansion chuck (1) for receiving a cutting tool, comprising a chuck base body (2, 3) with a connecting part (3) for fastening to a machine tool and with a clamping part (2) for clamping the cutting tool in a central receiving opening (4), wherein the clamping part (2) comprises at least one first expansion chamber (5) at the receiving opening (4) and a second expansion chamber (6) radially spaced therefrom.

2. Hydraulic expansion chuck (1) according to claim 1, wherein the first expansion chamber (5) comprises at least two separate sub-chambers (51, 52, 53) which are at the same radial distance from the central axis of the hydraulic expansion chuck (1).

3. Hydraulic expansion chuck (1) according to claim 2, wherein the first expansion chamber (5) comprises exactly three separate sub-chambers (51, 52, 53).

4. Hydraulic expansion chuck (1) according to claim 3, wherein the three partial chambers (51, 52, 53) have an identical size and geometry.

5. Hydraulic expansion chuck (1) according to one of the preceding claims, wherein the second expansion chamber (6) is annular.

6. Hydraulic expansion chuck (1) according to claim 4, wherein the second expansion chamber (6) comprises two chamber rings (61) connected in the axial direction by a connecting channel (63).

7. Hydraulic expansion chuck (1) according to one of the preceding claims, wherein the first expansion chamber (5) and the second expansion chamber (6) are fluidically connected to one another via a chamber channel (8).

8. Hydraulic expansion chuck (1) according to claim 2 and 6, wherein each sub-chamber (51, 52, 53) and the second expansion chamber (6) are connected via a separate chamber channel (8).

9. Hydraulic expansion chuck (1) according to claim 2 and 6, wherein each sub-chamber (51, 52, 53) of the first expansion chamber and the second expansion chamber (6) are connected via three separate chamber channels (8).

10. Hydraulic expansion chuck according to one of the preceding claims, further comprising an actuating unit (7) for pressurizing a fluid, wherein the actuating unit (7) is connected to the first expansion chamber (5) via a connecting channel (71).

11. Hydraulic expansion chuck according to one of the preceding claims, wherein the Receiving opening (4) comprises three slot openings (41) each spaced at an angle of 120°.

12. Hydraulic expansion chuck according to claim 2 and 11, wherein a partial chamber (51, 52, 53) is arranged between each two slot openings (41).

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