SHRINK-FIT CHUCK

Abstract

The invention concerns a shrink-fit chuck (1) for clamping an object, in particular for clamping a milling cutter in a milling machine, having a cylindrical receiving bore (3) for receiving a cylindrical shank of the object to be clamped, the receiving bore (3) extending in the shrink-fit chuck (1) and being bounded on the outside by a wall (4). The shrink-fit chuck (1) according to the invention is characterised by a rib (12) which extends transversely to the longitudinal axis (13) of the receiving bore (3) and projects inwards from the wall (4) of the receiving bore (3) into the receiving bore (3), so that the rib (12) permits the complete insertion of the shank (5) into the receiving bore (3) only in a predetermined angular position of the shank (5).

Claims

1-10. (canceled)

11. Shrink-fit chuck for clamping an object, comprising: a) a substantially cylindrical receiving bore for receiving a substantially cylindrical shank of the object to be clamped, the receiving bore extending in the shrink-fit chuck and being bounded externally by a wall, and b) a rib which extends transversely to the longitudinal axis of the receiving bore and projects inwards from the wall of the receiving bore into the receiving bore, so that the rib enables the shaft to be completely inserted into the receiving bore only in a specific angular position of the shaft.

12. Shrink-fit chuck according to claim 11, further comprising: a) a threaded bore which passes completely through the wall of the receiving bore and extends transversely to the longitudinal axis of the receiving bore, and b) a clamping screw which can be screwed into the threaded bore, b1) the clamping screw, in the screwed-in state, acting with its free end on a clamping surface in the circumferential surface of the shank and thereby preventing axial withdrawal of the object, b2) whereas in the unscrewed state the clamping screw does not act on the clamping surface of the shank and thus enables axial withdrawal of the object.

13. Shrink-fit chuck according to claim 12, wherein a) the threaded bore is arranged eccentrically with respect to the diameter of the receiving bore and thus does not extend exactly radially with respect to the longitudinal axis of the threaded bore, and b) the threaded bore extends in a plane which lies at right angles to the longitudinal axis of the receiving bore, and c) the threaded bore with its longitudinal axis does not intersect the longitudinal axis of the receiving bore.

14. Shrink-fit chuck according to claim 13, wherein the perpendicular distance between the longitudinal axis of the threaded bore and the diameter of the receiving bore is greater than 1 mm and less than 5 mm.

15. Shrink-fit chuck according to claim 11, wherein a) the rib has inside a straight edge which runs transversely to the longitudinal axis of the receiving bore, and b) the inclined clamping surface on the shank of the object to be clamped is substantially flat.

16. Shrink-fit chuck according to claim 15, wherein the rib is arranged behind the threaded bore for the clamping screw when viewed from the mouth of the receiving bore.

17. Shrink-fit chuck according to claim 12, wherein a) the clamping surface on the shank is inclined relative to the longitudinal axis of the shank by a specific angle of inclination so that the shank widens towards its free end, and b) the angle of inclination of the clamping surface on the shank is smaller than 10, and c) the angle of inclination of the clamping surface on the shank is greater than 0.1.

18. Shrink-fit chuck according to claim 17, wherein a) the inclined clamping surface on the shaft extends over an axial length of at least 5 mm, and b) the inclined clamping surface on the shaft extends over an axial length of at most 40 mm, and c) the inclined clamping surface on the shank extends in the axial direction up to the free end of the shank or at least up to a chamfer on the free end of the shank.

19. Shrink-fit chuck according to claim 11, wherein a) the receiving bore has an axial stop up to which the shank of the object to be clamped can be pushed into the receiving bore, b) the threaded bore for the clamping screw is arranged at a specific axial distance from the axial shoulder in the receiving bore, and c) the axial length of the clamping surface on the object to be clamped is greater than the axial distance between the threaded bore and the stop in the receiving bore.

20. Shrink-fit chuck according to claim 11, wherein the rib in the receiving bore together with the clamping surface on the shank of the article to be clamped has an angular positioning tolerance of at least 0.1 and at most 10 when the article is inserted into the shrink-fit chuck.

21. Machine tool with a shrink-fit chuck according to claim 11.

Description

[0025] Other advantageous further training of the invention is indicated in the dependent claims or is explained in more detail below together with the description of the preferred embodiment of the invention on the basis of the figures. They show:

[0026] FIG. 1 shows a longitudinal view through a shrink-fit chuck according to the invention,

[0027] FIG. 2 a cross-sectional view through the shrink-fit chuck as shown in FIG. 1 along section line A,

[0028] FIG. 3 a cross-sectional view through the shrink-fit chuck as shown in FIG. 1 along the section line B,

[0029] FIG. 4 a cross-sectional view through FIG. 1 in the area of the rib,

[0030] FIG. 5 a perspective view of a tool shaft for clamping in the shrink-fit chuck,

[0031] FIG. 6 a side view of the tool shaft from FIG. 5, as well as

[0032] FIG. 7 shows a front view of the tool shank from FIGS. 5 and 6 towards the free end of the tool shank.

[0033] The drawings show a shrink-fit chuck 1 according to the invention, which can be mounted in a machine tool (e.g. milling machine) by means of a standard taper interface 2, as it is known from DE 20 2014 008 275 U1.

[0034] On the tool side, the shrink-fit chuck 1 according to the invention has a cylindrical receiving bore 3, which is limited by a wall 4.

[0035] A tool shank 5 of a tool (e.g. milling cutter) can be inserted into the receiving bore 3 of the shrink-fit chuck 1, whereby the tool shank 5 is shown in FIGS. 5-7.

[0036] The wall 4 of the shrink-fit chuck 1 is completely penetrated by a threaded bore 6, whereby a clamping screw not shown can be screwed into the threaded bore 6, as known from DE 20 2014 008 275 U1.

[0037] On the one hand, the clamping screw in the threaded bore 6 prevents the tool shank 5 from being pulled out axially when screwed in. For this purpose, the clamping screw in the screwed-in state acts on an inclined clamping surface 7 in the circumferential surface of the tool shank 5. The clamping surface 7 is inclined at an angle of 2 with respect to a longitudinal axis 8, so that the tool shank 5 widens in the area of the clamping surface 7 towards its free end. The interaction of the clamping screw in the threaded bore 6 on the one hand with the clamping surface 7 on the other hand prevents the tool shank 5 from being pulled out of the shrink-fit chuck 1 in the axial direction.

[0038] On the other hand, the clamping screw in the threaded bore 6 also has a second function. In this way, the clamping screw screw screwed into the threaded bore 6 prevents the tool shank 5 in the receiving bore 3 from rotating under a mechanical load. For this purpose, the clamping screw screw screwed into the threaded bore 6 opposes the tool shank 5 with a torque which prevents the tool shank 5 from slipping through. To achieve this function, the threaded bore 6 in the wall 4 is eccentrically arranged with respect to a diameter 9 of the receiving bore 3 and at a perpendicular distance d=2 mm. This off-centre arrangement of the threaded bore 6 for the clamping screw enables the clamping screw to form an angular stop in the screwed-in position, which prevents the tool shank 5 from turning in the receiving bore 3.

[0039] It should also be mentioned that the shrink-fit chuck 1 has a shoulder 10 at the end of the receiving bore 3 which forms an axial stop for the tool shank 5. In addition, a length adjustment screw is also provided which forms an axial stop. The tool shank 5 can therefore only be inserted into the receiving bore 3 in the axial direction until the tool shank 5 touches the shoulder 10 or the length adjustment screw with its free end.

[0040] It should be mentioned here that the threaded bore 6 for the clamping screw is arranged at a certain axial distance a from the shoulder 10. The clamping surface 7 in the circumferential surface of the tool shank 5 has a corresponding axial length L. It is important here that the axial length L of the clamping surface of the tool shank 5 is greater than the distance a between the threaded bore 6 and the shoulder 10 in the receiving bore 3. This is important so that the clamping screw in the receiving bore 6 can act with its free end on the clamping surface 7 in the lateral surface of the tool shank 5.

[0041] It should also be mentioned that the tool shank 5 has a chamfer 11 at its free end. The chamfer 11 is located between the inclined clamping surface 7 and the free end of the tool shank 5. It is important that the inclined clamping surface 7 reaches up to the chamfer 11 without a cylindrical section remaining between the inclined clamping surface 7 and the free end of the tool shank 5.

[0042] In the receiving bore 3, a rib 12 is formed on the inside of the wall 4 of the receiving bore 3, which runs at right angles to the longitudinal axis 13 of the receiving bore 3 and projects inwards into the free cross-section of the receiving bore 3. The rib 12 has a straight edge, which allows the tool shank 5 to be positioned at an angle relative to the rib 12.

[0043] During a clamping operation, the shrink-fit chuck 1 is first heated in the conventional manner, which expands the receiving bore 3 and allows the tool shank 5 to be inserted.

[0044] The tool shank 5 is then inserted axially into the expanded receiving bore 3 until the tool shank 5 hits the rib 12 with its free end.

[0045] The operator then turns the tool shank 5 around its longitudinal axis 8 until the straight edge of the rib 12 is aligned parallel to the clamping surface 7 in the outer surface of the tool shank 5. In this angular position, the tool shank 5 can then be inserted further into the receiving bore 3 until the tool shank 5 finally strikes with its free end against the shoulder 10 in the receiving bore 3 or against the length adjustment screw.

[0046] The shrink-fit chuck 1 can then be cooled before the clamping screw is screwed into the threaded bore 6 until the free end of the clamping screw acts on the clamping surface 7 in the circumferential surface of the tool shank 5.

[0047] On the one hand, the screwed-in clamping screw then prevents axial extraction of the tool shank 5 from the shrink-fit chuck 1 in conjunction with the inclined clamping surface 7.

[0048] On the other hand, the screwed-in clamping screw also prevents the tool shank 5 from slipping, which could be caused by a torque load. Important for this function is a certain angular alignment of the tool shank 5 in relation to the clamping screw or the tapping hole 6. This correct angular alignment is achieved by the ingenious rib 12.

[0049] The invention is not limited to the preferred embodiment described above. Rather, a large number of variants and variations are possible which also make use of the invention idea and therefore fall within the scope of protection. In particular, the invention also claims protection for the subject-matter and the features of the dependent claims independently of the claims referred to in each case and in particular also without the features of the main claim. The invention thus comprises various aspects which enjoy protection independently of each other.

LIST OF REFERENCE SIGNS

[0050] 1 Shrink-fit chuck [0051] 2 Standard cone interface for mounting in a machine tool [0052] 3 Receiving bore for tool shank [0053] 4 Wall of the receiving bore [0054] 5 Tool shank [0055] 6 Threaded bore for clamping screw [0056] 7 Clamping surface in the surface of the tool shank [0057] 8 Longitudinal axis of the tool shank [0058] 8 Diameter of the receiving bore [0059] 9 Shoulder in the receiving bore [0060] 10 Chamfer at the end of the tool shank [0061] 11 Rib in the receiving bore [0062] 13 Longitudinal axis of the receiving bore [0063] d Distance between longitudinal axis of threaded bore and diameter of receiving bore [0064] L Axial length of the clamping surface [0065] a Distance between threaded bore and stop in the receiving bore