Tool spindle and machine tool comprising tool spindle

Abstract

To provide a highly precise and compact tool spindle, which is suitable in particular for centerless cylindrical grinding.SOLUTION: A tool spindle (1) comprises: a spindle shaft (3), which extends along a spindle axis and to which a tool can be coupled in a rotationally fixed manner at a tool interface (31); a spindle housing (2), which receives the spindle shaft (3); a drive device (5), which is coupled to a coupling section (33) of the spindle shaft (3) for rotationally driving, a bearing device (4), which supports the spindle shaft (3) in the spindle housing (2), where the spindle shaft (3), and preferably the spindle housing (2), is made of a material, which has, at least in one direction, a heat expansion coefficient of essentially zero.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a tool spindle and a machine tool equipped with the tool spindle. [Background technology]

[0002] A tool spindle is already known from Swiss Patent Application Publication No. 715948, which comprises a spindle shaft that can be coupled to a tool. The spindle shaft can be driven by a drive device. A bearing device supports the spindle shaft in a spindle housing. It is further proposed that the spindle shaft has a thermal expansion coefficient close to zero. The bearing device has two fixed bearing sections.

[0003] However, in Swiss Patent Application No. 715948, fixed bearing sections are provided on both sides of the drive unit.

[0004] However, a problem with the prior art is that there is a relatively large distance between the load application point of the tool and the fixed bearing section that is distant from the load application point. This can result in a relatively large deformation that does not meet very precise requirements. In addition, the entire tool spindle becomes relatively long and therefore relatively heavy. Therefore, accuracy is also affected thereby. The known tool spindle is not suitable for high-precision applications such as grinding machines, especially grinding machines for centerless cylindrical grinding. Summary of the Invention [Problem to be solved by the invention]

[0005] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a high precision, compact tool spindle that is particularly suitable for grinding machines, and more particularly for centerless cylindrical grinding.

[0006] The above object is solved by a tool spindle having the features of claim 1. [Means for solving the problem]

[0007] According to a first aspect, there is provided a tool spindle, preferably for a grinding machine, even more preferably for a centerless grinding machine, comprising a spindle shaft extending along a spindle axis and to which a tool can be coupled so as to be rotatably fixed at a tool interface, a spindle housing receiving the spindle shaft, a drive device coupled to a coupling section of the spindle shaft for rotational drive, and a bearing device supporting the spindle shaft in the spindle housing, wherein the spindle shaft, and preferably the spindle housing, are rotatably supported by a bearing device that is rotatable in at least one direction. * 10 -6 / K,-5 * 10 -6 / K and -2 * 10 -6 / K] lower limit and [+2 * 10 -6 / K,+5 * 10 -6 / K and +10 * 10 -6 In accordance with the present invention, a tool spindle is provided that is made from a material having a coefficient of thermal expansion, particularly essentially zero, within a range having an upper limit of [0.01 / K].

[0008] In particular, unlike the prior art, the present invention is characterized in that the bearing device has a first tool interface side fixed bearing section and a second coupling section side fixed bearing section, and the bearing device is arranged along the spindle axis between the tool interface and the coupling section and exclusively supports the spindle shaft.

[0009] Therefore, the tool interface-side fixed bearing section and the coupling-side fixed bearing section are located on one side of the coupling section, i.e., the tool interface side. This reduces the distance between the two fixed bearing sections. This reduces the length of the tool spindle along the spindle axis and thus its weight. Even in certain situations where high radial and / or axial loads must be absorbed, the absolute radial and axial deformation and deflection caused by the smaller free length between the fixed bearing sections can be further reduced, and preferably completely eliminated, at least between the fixed bearing sections. The two fixed bearing sections further prevent the transmission of vibrations generated in the coupling section. Therefore, the tool spindle according to the present invention can be used for high-precision applications, particularly centerless grinding.

[0010] It should be noted that by definition, a fixed bearing section is capable of absorbing radial and axial loads in opposite directions, and therefore transmitting them to the spindle housing.

[0011] Each fixed bearing section may comprise or be formed by at least one rolling bearing.

[0012] In particular, according to the present invention, there may be an interaction between a low thermal expansion coefficient and a bearing device, since a thermal expansion coefficient close to zero allows greater design freedom in the placement of the fixed bearing sections due to the low thermal expansion, facilitating the provision of two fixed bearing sections on one side of the connecting section. Due to the low thermal expansion coefficient, the fixed bearing sections can be placed at a small bearing distance, keeping absolute deformation small when thermal expansion occurs.

[0013] It should be noted that the ranges obtained by combining each specified lower limit with each specified upper limit of the thermal expansion coefficient are included in the present invention. * 10 -6 / K;+10 * 10-6 / K], [-5 * 10 -6 / K;+5 * 10 -6 / K] and [-2 * 10 -6 / K;+2 * 10 -6 Symmetric ranges such as [K] are particularly preferred.

[0014] The spindle housing and the spindle shaft may be formed from the same material.

[0015] The minimum distance between the first and second fixed bearing segments along the spindle axis is preferably equal to or greater than the maximum diameter of the spindle shaft in the area supported by the first and second fixed bearing segments.

[0016] This allows for a sufficient distance between the fixed bearing sections, thereby increasing the stiffness of the spindle shaft support, which is particularly advantageous since loads can also be introduced into the connecting section by the drive, and in particular allows for a sufficient stiffness to be guaranteed with respect to the maximum diameter occurring in the area between the fixed bearing sections.

[0017] At least one direction of thermal expansion is preferably radial to the spindle shaft, and even more preferably also along the spindle axis.

[0018] Therefore, the outer periphery of the tool that can be coupled to the tool shaft can be positioned with the highest precision and can absorb high loads acting on the periphery. This is particularly advantageous in the case of centerless cylindrical grinding machines, where particularly high loads act along the periphery. If the direction along the spindle axis is not additionally accompanied by thermal expansion, axial shift of the workpiece can be prevented and uniform removal of the workpiece can be ensured.

[0019] According to a further aspect, at least a first fixed bearing section can comprise a double row bearing.

[0020] Therefore, bearing stiffness can be increased on the tool interface side, thereby further improving tool guidance accuracy. Alternatively or additionally, the second fixed bearing section can comprise a double-row bearing. In the present disclosure, a double-row bearing comprises a configuration in which multiple rolling elements are arranged adjacent to each other in the axial direction. Therefore, this refers not only to a double-row bearing having only one inner bearing race and one outer bearing race, but also to bearings arranged directly behind each other in the axial direction, each having an inner bearing race and an outer bearing race that each contact each other in the axial direction.

[0021] According to yet a further aspect, at least one of the first fixed bearing section and the second fixed bearing section can be prestressed.

[0022] This reduces play in the bearing, further improving precision and increasing bearing rigidity.

[0023] According to yet a further aspect, at least the first bearing section can comprise an angular contact ball bearing.

[0024] This aspect allows for the absorption of relatively high combined radial and axial loads, as well as reduced vibration sensitivity, thereby improving overall accuracy, particularly concentricity accuracy.

[0025] The first fixed bearing section and the second fixed bearing section preferably define an O configuration.

[0026] Therefore, the respective virtual bearing points along the spindle axis can be shifted closer to the tool interface by the first fixed bearing section and closer to the coupling section by the second fixed bearing section, thereby further improving accuracy.

[0027] The spindle shaft is preferably formed as a hollow shaft.

[0028] Therefore, the weight can be reduced while at the same time ensuring the required bending stiffness, which in turn allows for improved accuracy of the machine tool when mounting the tool spindle on the machine frame.

[0029] According to yet a further aspect, the coupling section can be positioned further radially inward than the first fixed bearing section and the second fixed bearing section.

[0030] The rigidity of the support can be increased by the first and second fixed bearing sections. Additionally, excessive radial projection of the drive unit connected to the connecting section can be prevented. This ensures compactness of the tool spindle.

[0031] According to yet a further aspect, the drive device may be a rotating electric machine.

[0032] This allows for precise driving of the spindle shaft, and in particular for starting behavior, the acceleration and braking of the spindle shaft can be precisely controlled by the rotating electric machine, which is particularly advantageous since the rotating mass can be reduced due to the compactness of the spindle shaft.

[0033] According to yet a further aspect, the drive may be positioned coaxially with the spindle axis.

[0034] This prevents the drive device from protruding excessively in the radial direction, which contributes to making the tool spindle more compact.

[0035] The rotor of the rotating electrical machine may in particular be arranged directly and coaxially on the spindle shaft, so that the rotor can move integrally with the spindle shaft.

[0036] It is further advantageous if the drive is directly coupled to the coupling section and therefore without an intervening transmission device.

[0037] The material of the spindle shaft and / or the spindle housing preferably comprises carbon fiber reinforced plastic (CFRP), especially with different winding directions, and even more preferably is formed from CFRP.

[0038] This ensures a low coefficient of thermal expansion, essentially zero. It also ensures a relatively low weight and high rigidity, thus improving precision. The spindle housing and spindle shaft can be made from CFRP, but each can have a different winding or laying direction.

[0039] CFRP materials can be formed from unidirectional carbon fiber reinforced plastic materials, in which the fibers run parallel to the spindle axis. They can also be made from weaves with two preferred fiber directions perpendicular to each other, such as plain weave or twill weave. Additionally, the spindle shaft can have at least two differently oriented unidirectional layers, which are offset in opposite directions by the same angle, preferably 45°, relative to the spindle axis. The material structure can be radially symmetric. For a radial thermal expansion coefficient close to zero, the fibers can also have radial and axial components, and the fibers can preferably be inclined in at least two different directions, for example at an angle of 45° relative to the radial and axial directions, which can correspond to a kind of double helix.

[0040] CFRP materials can also be manufactured in a pre-forming process. CFRP materials can include short fibers, long fibers, or continuous fibers.

[0041] According to yet a further aspect, the tool spindle may further comprise a cooling device, preferably fluid-operated, designed to cool the first fixed bearing compartment and / or the second fixed bearing compartment and / or the drive device and / or the compartment between the coupling compartment of the spindle housing and the second fixed bearing compartment.

[0042] This prevents excessive heat generation, and reduces, preferably completely eliminates, deformation even in areas where the thermal expansion coefficient deviates from 0. The fluid-operated cooling device can be easily established.

[0043] The first and / or second fixed bearing section is preferably gas-cooled, preferably air-cooled, and / or the drive is liquid-cooled, preferably water-cooled.

[0044] Therefore, the cooling of the fixed bearing section can be simplified and implemented compactly, and in addition, a relatively large cooling capacity can be provided for the drive unit.

[0045] According to yet a further aspect, the tool spindle may be mounted to the machine frame and may include a fastening section coupled to the spindle housing.

[0046] The tool spindle can thus be provided as a separate element that can be removably fastened to the machine frame. The fastening section can be, for example, a flange.

[0047] A further aspect provides a machine tool, preferably a grinding machine, particularly preferably a centerless grinding machine, comprising a machine frame and a tool spindle according to at least one of the preceding aspects fastened to the machine frame.

[0048] Thus, the above aspects can be achieved in the case of machine tools.

[0049] The machine frame is preferably similarly * 10 -6 / K,-5 * 10 -6 / K and -2 * 10 -6 / K] lower limit and [+2 * 10 - 6 / K,+5 * 10 - 6 / K and +10 * 10 - 6 / K], in particular essentially zero.

[0050] This ensures compatibility between the tool spindle and the machine frame in terms of thermal expansion coefficients, thus avoiding the occurrence of restraint stresses. A symmetric range is preferred, as any combination of lower and upper limits for the machine frame is also conceivable.

[0051] Alternatively or additionally, the material of the spindle shaft may have a lower coefficient of thermal expansion than the coefficient of thermal expansion of the material of the machine frame.

[0052] The material of the machine frame can here be determined at the mounting section of the machine frame for the fastening section of the spindle housing.

[0053] This makes it possible to ensure high concentricity accuracy of the spindle shaft even when the machine frame has a higher thermal expansion coefficient.

[0054] Alternatively or additionally, the material of the machine frame may be non-metallic and may in particular comprise stone, in particular granite, and may preferably be at least partly, preferably completely, formed therefrom.

[0055] Thus, a robust machine frame with a low coefficient of thermal expansion can be achieved, this material selection being particularly possible in the mounting section of the machine frame for the fastening section of the spindle housing.

[0056] A further aspect of the invention relates to the use of a tool spindle according to one of the above aspects for a grinding machine, in particular for centerless grinding.

[0057] The present invention will now be described in detail with reference to the accompanying drawings. [Brief explanation of the drawings]

[0058] [Figure 1] FIG. 2 is a top view of a tool spindle according to the present invention. [Figure 2] FIG. 2 is a cross-sectional view taken along line AA in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0059] 1 shows a tool spindle 1. The tool spindle 1 can be fastened to a machine frame, such as a granite block of a grinding machine, which is an example of a machine tool. The tool spindle 1 can be used in particular for cylindrical grinding, and more particularly for centerless cylindrical grinding.

[0060] As essential components, the tool spindle 1 comprises a spindle housing 2 and a spindle shaft 3 extending along an axially defining spindle axis 3a.

[0061] The spindle housing 2 has a main body 2a and a cover 2b. The main body 2a can be formed integrally, in particular monolithically, as one element. At least the main body 2a of the spindle housing 2 can be made from the same material as the spindle shaft 3.

[0062] The body 2a extends essentially along the spindle axis and is a hollow cylindrical element having a circular cross section and an essentially constant outer diameter along the spindle axis, as can be seen in Figure 2 .

[0063] The spindle housing 2 axially defines two chambers, a bearing chamber 21 and a drive chamber 22, which are separated by an inwardly projecting protrusion 23, which may be omitted. Each of the two chambers has an essentially constant circular inner diameter. The inner diameters of the chambers 21, 22 are preferably the same size.

[0064] The bearing device 4 is disposed in the bearing accommodating chamber 21. The bearing device 4 is located between the spindle housing 2 and the spindle shaft 3 in the radial direction.

[0065] The drive housing 22 accommodates the drive 5. The drive 5 is here a rotating electrical machine, in particular an electric motor. It can be a DC or AC motor. In particular, an asynchronous motor can be provided as the drive 5.

[0066] The drive unit 5 is located radially between the spindle housing 2 and the spindle shaft 3. The drive unit has a stator 5a and a rotor 5b. The stator 5a is fixed inside the spindle housing 2, with a cooling sleeve 6 interposed therebetween.

[0067] The rotor 5b may have a rotor carrier and a rotor winding on the rotor carrier. The rotor 5b is attached to the spindle shaft 3 so as to be able to rotate integrally with the spindle shaft 3.

[0068] The spindle shaft 3 is formed as a rotationally symmetric hollow shaft. From left to right in Figure 2 along the spindle axis 3a, it has a tool interface section (tool interface in the terms of the claims) 31, a bearing section 32 and a coupling section 33.

[0069] The tool interface section 31 conically widens in the axial direction towards the coupling section 33. In the axial direction, the outer diameter D1 of the bearing section 32 is uniform and is smaller than the smallest outer diameter of the tool interface section 31.

[0070] Finally, the outer diameter of the coupling section 33 is also essentially uniform in the axial direction and is smaller than the diameter D1 of the bearing section 32.

[0071] The bearing device 4 is disposed on the outer periphery of the bearing compartment 32 with a uniform outer diameter.

[0072] The bearing device 4 is arranged between the tool interface section 31 and the coupling section 33 and has a first fixed bearing section 4a on the tool interface section 31 side and a second fixed bearing section 4b on the coupling section 33 side.

[0073] The first fixed bearing section 4a here has two identical rolling bearings, i.e. angular contact roller bearings, arranged axially directly adjacent to each other. The pressure lines of the angular contact roller bearings extend in the direction of the spindle axis relative to the tool interface section 31.

[0074] The second fixed bearing section 4b contains two identical rolling bearings, i.e., angular contact roller bearings, which are arranged axially directly adjacent to one another. The pressure lines of the angular contact roller bearings extend in the direction of the spindle axis into the connecting section 33. The first and second fixed bearing sections therefore define an O-arrangement. The outer ring of the fixed bearing section 4b rests against a protrusion 23 that separates two receiving chambers 21 and 22 of the same diameter.

[0075] The minimum axial distance L1 between the two fixed bearing sections 4a and 4b is set by two spacer sleeves 7a and 7b, which are radially spaced apart from each other. The radially outer spacer sleeve 7a is also a cooling sleeve.

[0076] The bearing arrangement 4 is prestressed by a clamping sleeve 11 which is screwed axially by means of a screw onto the shaft shoulder between the bearing section 32 and the connecting section 33 .

[0077] The rotor 5b is directly coupled to the coupling section 33 and is arranged coaxially therewith.

[0078] The tool spindle 1 further comprises at least one cooling device.

[0079] The cooling device 8a is designed for water cooling and is arranged to cool the drive device 5, in particular the stator 5a. It comprises a cooling sleeve 6, which has several circumferential grooves on its outer periphery, which are axially spaced apart from one another and connected to one another, through which a cooling fluid can flow. In addition, the cooling device 8a has connecting openings in the spindle housing 2, which communicate with the two circumferential grooves for the inflow and outflow of the cooling fluid, and connecting parts inserted into the connecting openings for circulating the fluid.

[0080] The cooling device 8b is similarly designed and arranged to cool the bearing device 4, and thus the first and second fixed bearing sections. It is also designed for liquid cooling and includes a cooling sleeve 7a, which has several circumferential grooves on its outer periphery, which are axially spaced apart from one another and connected to one another, through which a cooling fluid can flow. Here, connecting openings communicating with the circumferential grooves are also provided in the spindle housing 2. Further connections are provided for circulating a fluid into the connecting openings.

[0081] The further cooling device 8c is designed in particular for gas cooling the bearing compartment 4 with air. It comprises an air circulation chamber 9 radially between the sleeves 7a and 7b. Connection openings through the spindle housing 2 and the cooling sleeve 7a communicate with the air circulation chamber 9. Connections can be inserted into the connection openings.

[0082] Yet a further cooling device 8d is designed, in particular for gas cooling by air, and comprises at least one opening in the spindle housing 2 through the protrusion 23 and thus in the section of the housing axially between the coupling section 33 and the second fixed bearing section 4b or between the drive device 5 and the bearing device 4. The cooling fluid can be supplied via a connection through this opening.

[0083] A further cover 2c is provided axially opposite cover 2b and forms a stop for the outer race of first fixed bearing section 4a. Cover 2b closes the coupling end section of body 2a, and cover 2c closes the tool end section of body 2a.

[0084] An air barrier seal device 10 is provided to seal between the cover 2c and the spindle shaft 3.

[0085] According to the present invention, the spindle shaft 3 has a rotational speed of [-10 * 10 -6 / K,-5 * 10 -6 / K and -2 * 10 -6 / K] lower limit and [+2 * 10 -6 / K,+5 * 10 -6 / K and +10 * 10 -6 / K], for example, within a range with an upper limit of [-2 * 10 -6 / K;+2 * 10 -6 The entire spindle is made from a material having a thermal expansion coefficient in the range of [°C / °F]. For example, the spindle shaft can be made from CFRP. The spindle housing 2 can be made from the same material. The winding directions of the CFRP fibers can be the same or different from each other.

[0086] For example, the spindle shaft 3 may have at least two layers with different laying / winding directions, whereby the laying angles may be the same in amount relative to the spindle axis 3a and the radial direction, but point in opposite directions.

[0087] The functions and effects of the present invention will be described below.

[0088] Relatively large grinding discs with diameters of up to 500 mm are used as tools, for example, in the case of centerless cylindrical grinding. The grinding discs can be attached to the conical tool interface section 31, for example, via a conical tool holder. The tool can be clamped to the tool interface section 31 on the side of the tool interface section 31 facing away from the coupling section 33 via a flange section of the spindle shaft 3 onto which a clamping sleeve can be screwed.

[0089] The spindle shaft 3 must provide the required rotational speed of up to 6,000 revolutions per minute. As the grinding disc diameter increases, significant heat generation can occur. Nevertheless, to ensure high precision, especially concentricity, the spindle shaft 3, and additionally the spindle housing 2, are made from a material with a thermal expansion coefficient of essentially zero. This also helps to avoid thermally induced stresses.

[0090] By locating the bearing device 4 between the tool interface of the spindle shaft and the coupling section 33, and thus axially on one side of the coupling section 33 and the drive device 5, the resulting deformation can be kept small. The axial length can also be reduced. Thus, precision can be improved.

[0091] The length L1 is greater than the diameter D1 of the bearing section 31 and therefore the area supported by the bearing device, thereby ensuring sufficient rigidity for the diameter D1 and also absorbing the load of the drive device 5.

[0092] The material of the spindle shaft 3 and / or the spindle housing 2 may be essentially isotropic with respect to the coefficient of thermal expansion, but the coefficient of thermal expansion is at least essentially zero in the radial direction, thereby enabling high concentricity accuracy to be achieved.

[0093] The bearing arrangement 4 is in a prestressed O-arrangement. In addition, the fixed bearing sections 4a and 4b are each double-row bearings, here two adjacent angular contact roller bearings. Therefore, the bearing stiffness can be increased and high process forces can be absorbed. It should be noted that in this example, two single-row bearings directly adjacent to each other in the axial direction form a double-row bearing in each case. The two adjacent bearings are each arranged in an O-arrangement, thus a tandem O-arrangement.

[0094] The coupling section 33 is arranged further radially inward than the bearing section 31, and thus further inward than the inner diameter of the fixed bearing sections 4a and 4b. This allows for radial space to be created for the drive device. In addition, the individual bearings can simply be attached to the spindle shaft 3 from the side of the coupling section 33. This is particularly advantageous when the first fixed bearing section 4a and the second fixed bearing section 4b have the same inner diameter.

[0095] Furthermore, by arranging the rotating electric machine as the drive device 5 coaxially with the spindle shaft, space can be saved.

[0096] The cooling devices 8a-8d reduce heat generation and therefore protect the bearing device from deformation, even though it may be made from a material different from that of the spindle shaft and spindle housing, in particular a material with a higher thermal expansion coefficient.

[0097] The spindle shaft 33 is formed as a hollow shaft, which allows for a reduction in weight. Further components can additionally be accommodated in the interior space of the hollow shaft. For example, a balancing device with at least one counterweight can be provided in the interior space of the spindle shaft 33 at the end section of the spindle shaft on the side of the coupling section 33.

[0098] The spindle housing 2 may include a fastening section (not shown), such as a flange. This may be provided, for example, in the axial center section of the spindle housing and may protrude radially outward from the main body 2a. The tool spindle 1 can be fastened to a machine frame, e.g., granite, by means of this fastening section. For this purpose, several threads may be provided in through holes along the periphery of the fastening section.

[0099] At least in part, the machine frame may comprise a material having a higher coefficient of thermal expansion than the coefficient of thermal expansion of the spindle shaft material.

[0100] Here, a modification of the embodiment will be described.

[0101] The material of the spindle shaft and / or the spindle housing may be different from CFRP, for example, aramid fiber reinforced plastic may be used for at least one of the spindle shaft and the spindle housing.

[0102] At least one of the fixed bearing sections may not comprise an angular contact ball bearing. Bearings other than ball bearings may also be used. For example, a tapered roller bearing may be used in at least one of the fixed bearing sections.

[0103] The tool spindle can also be used in other machine tools, for example milling machines.

[0104] The spindle housing can also be formed in several parts, and therefore the body can include several parts.

[0105] The fixed bearing sections may also have different inner diameters, and therefore the bearing sections may have different outer diameters.

[0106] A gear may be provided between the drive device and the coupling device.

[0107] The protrusion 23 may be omitted. The inner diameter of the drive accommodating chamber 22 may be larger than the inner diameter of the bearing accommodating chamber 21.

Claims

1. A tool spindle (1), preferably for a grinding machine, even more preferably for a centerless grinding machine, comprising: a spindle shaft (3) extending along a spindle axis (3a) and to which a tool can be coupled so as to be rotatably fixed at a tool interface (31); a spindle housing (2) that receives the spindle shaft (3); a drive (5) coupled to the coupling section (33) of said spindle shaft (3) for rotary drive; a bearing device (4) that supports the spindle shaft (3) within the spindle housing (2); Equipped with The spindle shaft (3), and preferably the spindle housing (2), is preferably inclined relative to the rotational axis of the spindle shaft (3) in at least one direction. ＊ 10 －６ / K, -5 ＊ 10 －６ / K and -2 ＊ 10 －６ / K] and the lower limit of [+2 ＊ 10 －６ / K, +5 ＊ 10 －６ / K and +10 ＊ 10 －６ / K], in particular made from a material having an essentially zero coefficient of thermal expansion, The tool spindle (1), wherein the bearing device (4) has a first tool interface side fixed bearing section (4a) and a second coupling section side fixed bearing section (4b), and the bearing device (4) is arranged along the spindle axis (3a) between the tool interface (31) and the coupling section (3) and exclusively supports the spindle shaft.

2. 2. The tool spindle (1) according to claim 1, wherein a minimum distance (L1) between the first fixed bearing section (4a) and the second fixed bearing section (4b) along the spindle axis (3a) is equal to or greater than a maximum diameter (D1) of the spindle shaft (3) in the area supported by the first fixed bearing section (4a) and the second fixed bearing section (4b).

3. Tool spindle (1) according to claim 1 or 2, wherein at least one direction of thermal expansion is radial to the spindle shaft (3), and preferably also along the spindle axis (3a).

4. Tool spindle (1) according to at least one of claims 1 to 3, wherein at least the first fixed bearing section (4a) comprises a double row bearing.

5. Tool spindle (1) according to at least one of claims 1 to 4, wherein at least one of the first (4a) and second (4b) fixed bearing sections is prestressed.

6. Tool spindle (1) according to at least one of claims 1 to 5, wherein at least the first fixed bearing section (4a) comprises an angular contact ball bearing.

7. 7. Tool spindle (1) according to claim 6, wherein the first fixed bearing section (4a) and the second fixed bearing section (4b) define an O-configuration.

8. Tool spindle (1) according to at least one of claims 1 to 7, wherein the spindle shaft (3) is formed as a hollow shaft.

9. 9. The tool spindle (1) according to at least one of claims 1 to 8, wherein the coupling section (33) is arranged further radially inward than the first fixed bearing section (4a) and the second fixed bearing section (4b).

10. Tool spindle (1) according to at least one of claims 1 to 9, wherein the drive (5) is a rotary electric machine.

11. Tool spindle (1) according to at least one of claims 1 to 10, wherein the drive (5) is arranged coaxially with the spindle axis (3a).

12. 12. The tool spindle (1) according to claim 1, wherein the material of the spindle shaft (3) and / or the spindle housing (2) comprises, preferably is made of, carbon fiber reinforced plastic, in particular with different winding directions.

13. 13. The tool spindle (1) according to at least one of claims 1 to 12, further comprising a preferably fluid-operated cooling device (8a, 8b, 8c, 8d) designed to cool the first fixed bearing section (4a) and / or the second fixed bearing section (4b) and / or the drive device (5) and / or the section between a coupling section (33) of the spindle housing (2) and the second fixed bearing section (4b).

14. the first fixed bearing section (4a) and / or the second fixed bearing section (4b) are gas-cooled, preferably air-cooled, and / or Tool spindle (1) according to claim 13, wherein the drive (5) is liquid-cooled, preferably water-cooled.

15. Tool spindle (1) according to at least one of the preceding claims, further comprising a fastening section mountable to a machine frame and coupled to said spindle housing (2).

16. A machine tool, preferably a grinding machine, comprising: The machine frame, A tool spindle (1) according to at least one of claims 1 to 15, fastened to the machine frame; and preferably The mechanical frame is similarly ＊ 10 －６ / K, -5 ＊ 10 －６ / K and -2 ＊ 10 －６ / K] and the lower limit of [+2 ＊ 10 －６ / K, +5 ＊ 10 －６ / K and +10 ＊ 10 －６ / K], in particular essentially zero, and / or the material of the spindle shaft (3) has a thermal expansion coefficient that is lower than the thermal expansion coefficient of the material of said machine frame, and / or Machine tool, wherein the material of said machine frame is non-metallic, in particular comprises stone, more particularly granite, and is preferably formed at least partly, preferably entirely, therefrom.

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