"Machine tool unit with a fixation"

Abstract

A motor-driven machine tool unit (2) such as a multi-axis rotary head, a motor spindle (2), a rotary table, or the like, comprising a stator unit (9) and a rotor unit (10) having at least one rotor shaft (12) rotatable about a rotational axis, wherein the rotor unit (10) comprises at least one first bearing unit (1), in particular designed as a front fixed bearing (1), arranged in the region of a tool and / or workpiece holder (3), and at least one second bearing unit (4) spaced apart from the first bearing unit (1) for supporting the rotor shaft (12) in the stator unit (9), wherein at least one fixing device (5) is provided in the region of the first bearing unit (1) for fixing the rotatably mounted rotor unit (10), wherein the second bearing unit (4) is at least partially adjustable in the direction of the rotational axis, wherein the second bearing unit (4) comprises at least one ball bearing (4),wherein the ball bearing unit (4) comprises at least one common sleeve element (6), wherein in particular one / two inner rings or one / two outer rings of the ball bearing(s) (4) are arranged on the sleeve element (6), wherein an air gap (7) is arranged between the sleeve element (6) of the ball bearing unit (4) and the stator unit (9) or the rotor unit (10), wherein the air gap (7) is designed for the axial adjustment of the rotor unit (10) and / or the second bearing unit (4).

Description

[0001] The invention relates to a machine tool unit with a fixing device according to the preamble of claim 1. State of the art

[0002] Machine tool spindles typically feature two spaced-apart bearings for the spindle shaft. A first, front bearing is located near the tool or workpiece holder, and a second bearing is located at the opposite or rear portion of the spindle shaft.

[0003] Due to the specific requirements of machine tool spindles, and especially modern, powerful, and high-speed motor spindles, special spindle bearings or rolling bearings are typically used. However, since these bearings can only absorb radial forces when simultaneously subjected to axial loads, such angular contact ball bearings are used in a variety of arrangements so that the resulting bearing groups mutually apply the necessary preload. This means that each bearing arrangement generally consists of a pair of bearings.

[0004] A fixed bearing is generally provided in the front area of the spindle or motor spindle. With the help of a fixed bearing, fixation in two translational degrees of freedom is achieved. This means that this bearing point or the corresponding components are fixed in both the radial and axial directions. In the rear or opposite area of the spindle, especially the motor spindle, a loose bearing is generally provided. With a loose bearing, axial displacement of the bearing point or the corresponding components is possible. Accordingly, the spindle shaft is held in position by the fixed bearing, while the loose bearing allows, for example, thermal expansion in the longitudinal direction. These rear bearings currently comprise deep groove / roller bearings to enable axial adjustment.

[0005] In addition, so-called milling-turning spindles already exist, which, during one machining phase, operate as a motor spindle with milling tools and, during another operating phase, are fixed in place by means of a fixing device on the rotor unit / shaft, i.e., are designed to be non-rotatable, for example, to accommodate a turning tool or the like and be available for turning operations. The fixing device is designed to prevent radial rotation.

[0006] Furthermore, a machine tool with a controllable locking device is known from DE 39 13 139 A1.

[0007] A spindle with a floating bearing and a fixed bearing has become known from US 2006 / 0104553 A1. Object and advantages of the invention

[0008] The object of the invention is to propose a machine tool unit that enables extended operating modes and can be used more flexibly.

[0009] This object is achieved, starting from a machine tool unit of the type mentioned in the introduction, by the characterizing features of claim 1. Advantageous embodiments and further developments of the invention are possible by the measures mentioned in the subclaims.

[0010] Accordingly, a machine tool unit according to the invention is characterized in that the second bearing unit comprises at least one ball bearing, wherein the ball bearing unit comprises at least one common sleeve element, wherein in particular one / two inner rings or one / two outer rings of the ball bearing(s) are arranged on the sleeve element, wherein an air gap is arranged between the sleeve element of the ball bearing unit and the stator unit or the rotor unit, wherein the air gap is designed for the axial adjustment of the rotor unit and / or the second bearing unit.

[0011] Surprisingly, it has been shown that not only a cylindrical / roller bearing can be used as a loose bearing, e.g. in a turning / milling spindle, but also an advantageous ball bearing or ball bearing unit.

[0012] This air gap enables the second bearing unit or the second bearing to be adjusted and thus, for example, advantageously allows thermal expansion of the motor shaft / motor shaft unit in the area of this floating bearing, so that no negative thermal stresses should arise.

[0013] Preferably, an O- or X-arrangement of two ball bearings of the ball bearing unit is provided. In this case, they are clamped together axially and radially.

[0014] The air gap and / or the sleeve element is advantageously fixed or partially eliminated by means of a fixing unit or second fixing device. This advantageously allows for clamping or bracing of the rotor unit / rotor shaft to the stator unit, particularly a flange element. This means that the air gap is eliminated by means of a clamping / fixing force, creating, for example, a force-locking connection.

[0015] Preferably, a stop in the radial direction is realized by means of the fixing unit in the area of the second bearing unit. Accordingly, no radial adjustment can occur / take place in this particular operating phase. This is particularly advantageous in an operating phase wherein the machine tool unit is used for turning the workpiece, in particular as a “passive” turning headstock, e.g. with a turning tool or a statically arranged, i.e. non-rotating twist drill or the like. This means that the workpiece is rotated by means of a separate drive and the machine tool unit according to the invention is firmly fixed, in particular by means of the fixing device in the area of the tool / workpiece holder, and also in the area of the floating bearing by means of the fixing unit. Example

[0016] An embodiment is shown in the drawing and is explained in more detail below with reference to the figures.

[0017] In detail: Fig. 1 a schematic section of a motor spindle according to the invention with fixable floating bearing and Fig. 2 a schematic representation of a turning-milling arrangement.

[0018] In Fig. Figure 1 schematically shows a motor spindle 2 with a workpiece / tool holder 3. A front fixed bearing 1 has two ball bearings. The two ball bearings 4 are arranged in an O-arrangement or an X-arrangement and are thus firmly fixed as a fixed bearing 1 in both the radial and axial directions (in the direction of the rotational axis 15).

[0019] For fixing the rotor shaft or rotor shaft unit 10, a fixing device 5 is provided, e.g. realized as a so-called Kostyrka clamp.

[0020] In addition, a second fixation or fixing unit 12 is provided. This fixing unit 12 comprises a clamping membrane 11, in particular a metal membrane or membrane sleeve, which is welded or fastened on both sides to a flange element 13 of the stator unit. By means of a hydraulic unit 14, hydraulic fluid can act on the membrane at, for example, approximately 350 bar, so that it clamps or fixes in the area of the second bearing unit 4. This can effectively prevent tilting or the like of the rotor shaft or rotor shaft unit 10, especially during turning, although an air gap 7 is present in the radial direction between a sleeve 6 and the stator for the axial adjustability of the floating bearing or second bearing 4.

[0021] Especially in Fig. 2 schematically shows an embodiment for an application in which a motor spindle 2 can be adjusted from a milling position A to a rotational position B. In the milling position A, the motor spindle 2 is operated, for example, with a milling tool, ie the rotor unit 10 is set in rotational movement by the electromagnetic drive system.

[0022] In a rotational position, the motor spindle 2 is adjusted into the rotational axis 15 of the rotational system, i.e. concentrically, by means of an XZZ positioning system or the like (not shown in detail), wherein the rotor unit 10 is firmly fixed with the fixing device 5 and also with the fixing unit 12.

[0023] It is clear that the motor spindle is built / realized extremely short in order to achieve the largest possible working width according to Fig.2. For this purpose, the entire drive / cooling / release system components or the like are arranged within the stator or essentially within the electromagnetic drive system.

[0024] The fixing unit 6 can be fixed hydraulically, pneumatically or mechanically.

Claims

[1] A motor-driven machine tool unit (2) such as a multi-axis rotary head, a motor spindle (2), a rotary table, or the like, comprising a stator unit (9) and a rotor unit (10) having at least one rotor shaft (12) rotatable about a rotational axis, wherein the rotor unit (10) comprises at least one first bearing unit (1), in particular designed as a front fixed bearing (1), arranged in the region of a tool and / or workpiece holder (3), and at least one second bearing unit (4) spaced apart from the first bearing unit (1) for supporting the rotor shaft (12) in the stator unit (9), wherein at least one fixing device (5) is provided in the region of the first bearing unit (1) for fixing the rotatably mounted rotor unit (10), wherein the second bearing unit (4) is at least partially adjustable in the direction of the rotational axis, wherein the second bearing unit (4) comprises at least one ball bearing (4),wherein the ball bearing unit (4) comprises at least one common sleeve element (6), wherein in particular one / two inner rings or one / two outer rings of the ball bearing(s) (4) are arranged on the sleeve element (6), wherein an air gap (7) is arranged between the sleeve element (6) of the ball bearing unit (4) and the stator unit (9) or the rotor unit (10), wherein the air gap (7) is designed for the axial adjustment of the rotor unit (10) and / or the second bearing unit (4). [2] Machine tool unit (2) according to claim 1, characterized by that the second bearing unit (4) is designed as a ball bearing unit (4) comprising at least two ball bearings. [3] Machine tool unit (2) according to one of the preceding claims, characterized bythat at least in the region of the second bearing unit (4) at least one fixing unit (12) is provided for fixing the rotatably mounted rotor unit (10) and / or the ball bearing unit (4) and / or for at least partially eliminating the air gap (7). [4] Machine tool unit (2) according to one of the preceding claims, characterized by that at least the fixing unit (12) is arranged between the rotor unit (10) or the stator unit (9) and the ball bearing (4) or the ball bearing unit (4) or the sleeve element (6). [5] Machine tool unit (2) according to one of the preceding claims, characterized by that the fixing unit (12) is designed as at least one pressurizable, hydraulic fixing unit (12). [6] Machine tool unit (2) according to one of the preceding claims, characterized by that at least one flange element of the stator unit (9) comprises at least the fixing unit (12). [7] Machine tool unit (2) according to one of the preceding claims, characterized by that the fixing unit (12) comprises at least one fixing membrane which is partially adjustable in the radial direction.

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