RELEASE UNIT FOR A MACHINE TOOL SPINDLE

Abstract

A release unit for a machine tool spindle, in particular motor spindle, for releasing a tool clamp, wherein the release unit comprises at least one adjustment element which can be linearly adjusted along an adjustment path for actuating the tool clamp, which release unit reduces the structural and/or economic complexity. This is achieved according to the invention in that the release unit is constructed as an electric motor which comprises an electromagnetic drive system having a hollow-cylindrical rotor shaft which rotates about a rotation axis, in that the linearly adjustable adjustment element is constructed as a spindle element of a conversion unit for converting the rotation of the electric motor into a linear adjustment and in that the rotor shaft is constructed as a spindle nut of the conversion unit which rotates about the rotation axis.

Claims

1. A release unit for a machine tool spindle for releasing a tool clamp, wherein the release unit comprises at least one adjustment element which can be linearly adjusted along an adjustment path for actuating the tool clamp, wherein the release unit is constructed as an electric motor which comprises an electromagnetic drive system having a hollow-cylindrical rotor shaft which rotates about a rotation axis, wherein the linearly adjustable adjustment element is constructed as a spindle element of a conversion unit for converting the rotation of the electric motor into a linear adjustment and wherein the rotor shaft is constructed as a spindle nut of the conversion unit which rotates about the rotation axis.

2. The release unit as claimed in claim 1, wherein the rotor shaft of the electric motor is constructed as a magnet carrier element which comprises at least one permanent magnet of the drive system.

3. The release unit as claimed in claim 1, wherein the rotor shaft of the electric motor comprises at least one thread turn of the conversion unit.

4. The release unit as claimed in claim 1, further comprising roller members arranged between the spindle nut and the spindle element.

5. The release unit as claimed in claim 1, wherein in order to support the rotor shaft, the electromagnetic drive system of the electric motor is substantially arranged between a first bearing and at least a second bearing.

6. The release unit as claimed in claim 5, wherein at least one of the bearings is constructed as an angular roller bearing.

7. The release unit as claimed in claim 4, wherein in order to support the spindle element, the roller members are arranged between a first plain bearing and at least a second plain bearing.

8. The release unit as claimed in claim 7, wherein the rotor shaft comprises at least a first sliding face of the first plain bearing and/or a stator of the electric motor comprises at least a second sliding face of the second plain bearing.

9. The release unit as claimed in claim 5, wherein the first and/or second bearing of the rotor shaft is constructed at least as an axial bearing of the spindle element for receiving forces which are orientated in the direction of the rotation axis.

10. The release unit as claimed in claim 1, wherein a stator of the electric motor comprises at least one linear guiding device for guiding the spindle element along the adjustment path.

11. A machine tool spindle having a release unit for releasing a tool from a retention device for retaining the tool in a processing phase, wherein the release unit is constructed as claimed in claim 1.

12. The release unit of claim 1, wherein the machine tool spindle is a motor spindle.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0040] An embodiment of the present invention is illustrated in the drawings and is explained in greater detail below with reference to the Figures.

[0041] FIG. 1 is a schematic first section through a release unit according to the present invention; and

[0042] FIG. 2 is a schematic second section through the release unit according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0043] FIGS. 1 and 2 illustrate an electric release unit 1 which comprises an electric motor 2 with a stator 3 and a rotor 4. The stator 3 with electromagnetic coils 8 has at the peripheral side/outer side a stator housing 5 which forms with a stator ring 6 a hollow-cylindrical or annular cooling channel 7 for cooling water.

[0044] The rotor 4 comprises a rotor shaft 9 to which at the peripheral side permanent magnets 10 are fixed, in particular, adhesively bonded and bound. The rotor shaft 9 is supported with a ball bearing 11 and an angular roller bearing 12, wherein the latter can not only absorb radial forces, but also particularly axial forces.

[0045] The absorption of axial forces is quite particularly significant since a linear drive 13 or a conversion unit 13 is arranged inside the hollow-cylindrical rotor shaft 9. The rotation of the rotor 4 or the rotor shaft 9 is thereby advantageously converted into a linear adjustment or translation in an axial direction or in the direction of the (concentric) rotation axis 14 of the electric motor 2.

[0046] The linear drive 13 is constructed as a ball screw drive 13 so that it comprises numerous balls 15 as roller members 15. They are arranged, on the one hand, between the rotor shaft 9 which at the same time forms the spindle nut 9 of the linear drive 13 and a spindle element 16 and, on the other hand, between two plain bearings 17, 18 for supporting the spindle element 16 which in addition to the balls 15 can form a radial support/guide of the spindle element 16. An advantageous ball return unit to axially return the balls during operation is not illustrated in greater detail and is arranged/constructed inside the rotor shaft 9 as a channel.

[0047] With a rotating/running electric motor 2 or rotating rotor shaft 9, the spindle element 19 is adjusted along the rotation axis in the direction of a travel H. For example, a thread pitch of approximately 5 mm is provided and a travel H is approximately from 8 to 20 mm long and presses with approximately 45 kN so that the electric release unit 1 can replace a previously conventional hydraulic release unit, wherein a connection flange 33 has corresponding fixing possibilities or screw holes in order to be able to be screwed/fixed to the rear end of a motor spindle which is not illustrated in greater detail or a tool clamp.

[0048] In order to release such a tool clamp, there is provided a stop 19 which activates or releases a tension rod. In FIGS. 1 and 2, the spindle element 16 is illustrated in the non-activating position or idle position, that is to say, the spindle element 16 is retracted. In this retracted idle position, a sensor 20 or end switch 20 may advantageously detect or establish the rest position. In the illustrated variant, there is introduced in the hollow-cylindrical spindle element 16 a separate element 22, for example, magnet for a Hall sensor or the like, which the sensor 20 can advantageously detect. The sensor 20 may also be constructed as a proximity sensor 20 so that a groove 21 or recess together with the spindle element 16 advantageously makes the idle position detectable for the sensor 20. In FIG. 1, a second, separate element 23 is further schematically illustrated, whereby the stop position or deployed end position of the spindle element can be detected. For the deployed end position, the plain bearing element 18 advantageously has a stop for stopping on the rotor shaft 9.

[0049] Furthermore, there is provided a (relative) rotary encoder 24 which can detect the angular position of the rotor shaft 9. In this instance, a so-called encoder 25 and a tooth ring 26 are provided, whereby the angular position can be detected.

[0050] Furthermore, for the linear drive 13 preferably two linear guides 27 or torque supports 27 are provided. This supports the spindle element 16 in a peripheral direction on the stator 3, wherein a rotation of the spindle element 16 is effectively prevented. There is thereby produced with the rotating electric motor 2 or rotating rotor shaft 9 a relative movement between the rotor shaft 9 or spindle nut 9 and the spindle element 16 so that the spindle element 16 is advantageously adjusted in the direction H and, when the rotation direction of the electric motor 2 or the rotor shaft 9 is reversed, is returned again (counter to the direction H). Consequently, a release force in the direction H and where required a counter-force or clamping force counter to the direction H may be produced. The drive forces are advantageously transmitted via the balls 15 and corresponding thread turns 31, 32 of the rotor shaft 9 and the spindle element 16.

[0051] The axial forces are advantageously directed via the stop 19 or the spindle element 16 and via the balls 15, in particular, to the angular roller bearing 12.

[0052] For advantageous bearing or guiding, the linear guides 27 each have a fixing screw 28 on which a roller bearing 29 is supported with the outer ring and rollers as a roller member. The friction during linear guiding of the spindle element 16 on a planar guiding face 30 of the stator 3 is thereby reduced or minimized.

[0053] The spindle element 16 is constructed in a hollow-cylindrical manner in order centrally at the inner side to transport or direct a medium, in particular, a cooling lubricant or the like.

LIST OF REFERENCE NUMERALS

[0054] 1 Release unit [0055] 2 Electric motor [0056] 3 Stator [0057] 4 Rotor [0058] 5 Housing [0059] 6 Ring [0060] 7 Cooling channel [0061] 8 Coil [0062] 9 Rotor shaft [0063] 10 Permanent magnet [0064] 11 Bearing [0065] 12 Bearing [0066] 13 Linear drive [0067] 14 Rotation axis [0068] 15 Balls [0069] 16 Spindle element [0070] 17 Plain bearing [0071] 18 Plain bearing [0072] 19 Stop [0073] 20 Sensor [0074] 21 Groove [0075] 22 Element [0076] 23 Element [0077] 24 Rotary encoder [0078] 25 Encoder [0079] 26 Tooth ring [0080] 27 Linear guide [0081] 28 Screw [0082] 29 Roller bearing [0083] 30 Level [0084] 31 Thread turn [0085] 32 Thread turn [0086] 33 Connection flange