Spindle arrangement of a machine tool

Abstract

The invention relates to a spindle arrangement of a machine tool, comprising: a main spindle (2) having a spindle shaft (3), a spindle housing (4) and precisely one clamping set (8); a first centring interface (6) on the spindle shaft (3); and a second centring interface (7) on the spindle housing (4), wherein the first centring interface (6) is designed to provide a first centring between the spindle shaft (3) and a tool holder (100), wherein the clamping set clamps the tool holder (100), and wherein the second centring interface (7) is designed to provide a second centring between the spindle housing (4) and a tool holder element (5), wherein the clamping set (8) clamps the tool holder element (5) in such a way that a gap (10, 11) remains at the first centring interface.

Description

[0001] Spindle arrangement of a machine tool

[0002] Description

[0003] The present invention relates to a spindle arrangement of a machine tool with improved variability of applications by means of an additional centering interface.

[0004] Spindle arrangements for machine tools are known in various designs from the state of the art. When selecting a machine tool's main spindle, a compromise is always sought between spindle rigidity, which requires large ball bearings, and a maximum possible speed, which limits the bearing size. A main spindle that is very rigid for machining with large tools and has high speeds for machining with small tools would be desirable. However, this is not technically possible. In practice, so-called auxiliary spindles are therefore used. These are clamped at a clamping interface on the main spindle, where the tool holders for various tools are also clamped, e.g., a hollow shank taper (HSK) clamping interface. However, this limits the rigidity of the connection between the auxiliary spindle and the main spindle.Undesirable vibrations occur during operation, and machining quality is often inadequate. Therefore, front spindles are rarely used in practice.

[0005] It is an object of the present invention to provide a spindle arrangement of a machine tool which, with a simple structure and simpler, cost-effective manufacture, enables expanded application possibilities for various tool holder elements and in particular front spindles.

[0006] This object is achieved by a spindle arrangement having the features of claim 1. The subclaims show preferred developments of the invention.

[0007] The spindle arrangement of a machine tool according to the invention with the features of claim 1 has the advantage that a second centering interface is provided on a spindle housing in addition to a first centering interface on the spindle shaft. The spindle arrangement thus comprises a main spindle with a spindle shaft and the spindle housing as well as precisely one clamping set which is arranged on the spindle shaft. The clamping set clamps a tool holder, wherein the first centering interface is designed to provide centering between the spindle shaft and the tool holder. The spindle shaft is preferably a hollow shaft and the first centering interface is preferably arranged on the hollow shaft. The clamping set is preferably a hollow shank taper clamping set. The spindle arrangement further comprises a second centering interface on the spindle housing.The second centering interface is configured to provide a second centering point between the spindle housing and a tool holder. The clamping set clamps the tool holder such that a gap remains at the first centering interface.

[0008] Thus, the clamping set clamps a tool holder at the first centering interface on the spindle shaft, with the second centering interface not performing a centering function, and the clamping set clamps a tool holder element on the spindle housing, with the first centering interface on the spindle shaft not performing a centering function. The single clamping set is thus used to clamp a tool holder and a tool holder element. A key advantage of the invention is that there is only one clamping set, with which both standard tools can be clamped using the tool holder on the spindle shaft and tool holder elements on the spindle housing.

[0009] The tool receiving element is preferably an auxiliary spindle or a tool holder. This solves the previously unsolved problem in the prior art of clamping large tools with maximum rigidity using the first centering interface, while at the same time allowing a tool receiving element, in particular an auxiliary spindle or another tool, to be operated at high speeds by centering at the second centering interface.

[0010] Thus, the spindle arrangement according to the invention can, on the one hand, be used in the usual way by centering at the first centering interface with tools and, on the other hand, can be operated by centering at the second centering interface, in particular with an auxiliary spindle.

[0011] Preferably, the first centering interface is a hollow shank taper (HSK) interface. Thus, the invention can be used on a standardized interface in conjunction with a hollow spindle shaft. Further preferably, the tool holder element is designed in the region of the first centering interface such that, when the tool holder element is clamped, a first gap is present on a conical contact surface of the hollow shank taper interface between the spindle shaft and the tool holder element. Further preferably, a second gap is formed on a flat contact surface of the hollow shank taper interface between the spindle shaft and the tool holder element.

[0012] For a particularly compact design, the spindle arrangement is preferably designed such that the second centering interface is arranged on a front side of the main spindle.

[0013] The second centering interface is further preferably arranged in an annular region of the spindle housing, in particular adjacent to the spindle shaft or adjacent to a labyrinth seal. Several connections for power lines and / or signal lines and / or media channels are preferably arranged in the annular region of the spindle housing. These connections are preferably used to supply an auxiliary spindle.

[0014] The second centering interface preferably has centering elements that provide a positive connection between the main spindle and the tool holder element. The centering elements of the second centering interface are preferably webs and grooves, in particular each with conical contact surfaces. The webs preferably extend radially to a spindle axis. The webs are formed either in the spindle housing and / or in the tool holder element, and the grooves are formed on the corresponding other component.

[0015] The second centering interface further preferably comprises, as a centering element, additional planar surfaces for axial contact between the spindle housing of the main spindle and the tool holder element.

[0016] The centering elements of the second centering interface are preferably arranged in the circumferential direction in positions that are equally spaced from one another, in particular four centering elements are arranged at positions that are each 90° apart from one another.

[0017] The centering elements are preferably arranged on the annular region of the spindle housing and in particular are introduced into the annular region.

[0018] The spindle assembly further preferably comprises an activatable support device that establishes and releases a connection between the spindle housing of the main spindle and the spindle shaft. This ensures that the clamping forces of the clamping set do not act on the main bearings of the main spindle when the tool holder element is clamped against the spindle housing by the clamping set at the second centering interface. The clamping forces of the clamping set are transmitted from the spindle shaft to the spindle housing via the support device once the support device has established the connection between the spindle housing and the spindle shaft.

[0019] The support device preferably comprises pins and springs, wherein the springs preload the pins in a retracted position such that no connection is formed between the spindle housing of the main spindle and the spindle shaft.

[0020] Preferably, the support device engages in a recess formed in the spindle shaft or the support device can be extended in front of a shoulder on the spindle shaft.

[0021] Further preferably, the first centering interface and the second centering interface are located in a common plane E. This keeps the longitudinal extension of the spindle arrangement as small as possible.

[0022] Further preferably, a clamping point of the clamping set and the second centering interface also lie in a common plane E, or the clamping point is cut by the plane E.

[0023] The tool holder is preferably an auxiliary spindle, particularly for small tools that can be operated at high speeds, or a tool holder, e.g., for stationary turning tools. The auxiliary spindle is preferably a full-fledged spindle with its own drive, with the auxiliary spindle being mounted on a smaller diameter than the main spindle.

[0024] Preferred embodiments of the invention are described in detail below with reference to the accompanying drawings. In the drawing:

[0025] Fig. 1 is a perspective view of a spindle arrangement with an attachment spindle in an exploded view of a preferred embodiment of the invention from a first perspective,

[0026] Fig. 2 is a perspective exploded view of the spindle assembly of Fig. 1 in a second perspective,

[0027] Fig. 3 is a schematic sectional view of the spindle arrangement of Fig. 1 with mounted front spindle,

[0028] Fig. 4 is a schematic, enlarged partial sectional view of the spindle assembly of Figure Fig. 5 is a schematic partial sectional view of the spindle assembly with a clamped tool holder centered only at a second centering interface and

[0029] Fig. 6 is a schematic sectional view of a spindle arrangement in which a tool holder is centered on the first centering interface.

[0030] A spindle arrangement 1 according to a preferred embodiment of the invention with various clamped devices is described in detail below with reference to Figures 1 to 6.

[0031] The spindle assembly 1 comprises a main spindle 2 with a spindle shaft 3. The spindle shaft 3 is mounted on a first bearing assembly 21 and a second bearing assembly 22 (see Fig. 3).

[0032] To secure the first bearing assembly 21 of the main spindle 2, a spindle nut 12 is screwed onto a correspondingly shaped external thread on an outer circumference of the spindle shaft 3. Reference numeral 13 denotes a labyrinth seal for sealing the first bearing assembly 21 of the main spindle 2.

[0033] The spindle shaft 3 is a hollow shaft. The spindle assembly 1 further comprises a clamping set 8, which is designed as a clamping set for hollow shank tapers (HSK) and is located in the spindle shaft 3. In addition, the spindle shaft 3 comprises a first centering interface 6 with a planar contact 81 and a conical contact surface 80, on which tool holders designed as hollow shank tapers can be centered. The conical contact surface 80 is directed towards the clamping set 8. The planar contact 81 is aligned perpendicular to a spindle axis (center axis) XX of the spindle assembly (see Fig. 4). Thus, the main spindle

[0034] 2 has a standardized clamping point.

[0035] The main spindle 2 further comprises a multi-part spindle housing 4, which in the figures

[0036] 3 and 4 is only shown schematically and has a drive 20.

[0037] The spindle assembly further comprises a second centering interface 7, which is arranged on the spindle housing 4. The second centering interface 7 is shown in detail in Figures 1 and 2. Figures 1 and 2 show two perspective views of the spindle assembly 1 from different perspectives. In addition to the main spindle 2, a tool holder element 5 is shown, which in this embodiment is an auxiliary spindle 50.

[0038] The second centering interface 7 comprises webs 70 formed on the auxiliary spindle 50 and grooves 71 formed on a spindle housing 4. Four webs 70 and four grooves 71 are provided, each offset by 90°. The grooves 71 are formed in an annular region 40 on an end face of the spindle housing 4, which is also the end face of the main spindle 2.

[0039] To supply the front spindle 50 with power and / or signals and / or media, several connections 72 are schematically shown in the annular area 40 of the spindle housing 4, which connections can be connections for power lines and / or signal lines and / or media channels.

[0040] The second centering interface 7 thus has webs 70 and grooves 71 as centering elements, with preferably conical contact surfaces formed between the webs and grooves. Furthermore, flat surfaces 73 are provided on the annular region 40 for centering, with the flat surfaces 73 being formed perpendicular to the spindle axis XX. Corresponding flat surfaces 57 are formed on the tool holder element 5.

[0041] Thus, the second centering interface 7 has both positive centering elements and flat centering elements (plane surfaces).

[0042] The first centering interface 6 is configured to provide a first centering between the spindle shaft 3 and a tool holder 100, as shown in Fig. 6. The clamping set 8 clamps the tool holder 100. As can be seen from Fig. 6, the second centering interface 7 on the front side of the spindle housing 4 is without function.

[0043] Centering by means of the first centering interface 6 takes place both on the conical contact surface 80 of the hollow shank taper interface and on the flat contact surface 81 of the hollow shank taper interface. The tool holder 100 is driveless and is driven by the main spindle 2. The tool holder 100 accommodates a tool 101, for example, a milling cutter.

[0044] In contrast to Fig. 6, Figures 3 and 4 show the use of a tool holder element 5 in the form of the attachment spindle 50, which can be seen in detail in Fig. 3.

[0045] The front spindle 50 comprises a drive 52, a first bearing arrangement 53 and a second bearing arrangement 54. A tool is designated by the reference numeral 55.

[0046] The first and second bearing arrangements 53, 54 are located on a first diameter D1, which is significantly smaller than a second diameter D2, on which the first and second bearing arrangements 21, 22 of the main spindle are arranged.

[0047] This makes it possible for the auxiliary spindle 50 to be operated at very high speeds, which are higher than the maximum speeds of the main spindle. Power, signal, and media are supplied via connections 72. To prevent the clamping forces of the clamping set 8 from acting directly on the bearing arrangement 21 and 22 of the main spindle when the auxiliary spindle 50 is clamped against the second centering interface 7 on the spindle housing 4, a support device 9 is provided. The support device 9 comprises pins 90 and springs 91, wherein the springs 91 hold the pins 90 in a retracted position that releases the spindle shaft 3. The pins 90 are brought into an engaged position, for example by compressed air, so that a connection is formed between the spindle housing 4 and the spindle shaft 3. The pins 90 engage in recesses 30, e.g. a circumferential groove, which are formed in the spindle shaft 3, in the engaged state (see in particular Fig.4). The forces of the clamping set 8 when the front spindle 50 is clamped to the spindle housing 4 can be transmitted from the spindle shaft 3 to the spindle housing 4 via the pins 90 of the support device 9. However, during machining with a tool holder 100 that is clamped to the spindle shaft 3 with the clamping set 8 and centered at the first centering interface 6 on the spindle shaft 3, the pins 90 of the support device 9 are in a retracted position and thus disengaged (see Fig. 6).

[0048] The engagement position of the support device 9 is shown in Figures 3 and 4. In Fig. 6, the retracted position of the pins 90 is shown, since the tool 101 in Fig. 6 is driven directly by the main spindle 2.

[0049] As can be seen in detail in Fig. 4, the front spindle 50 is clamped to an annular neck 56 by means of the clamping set 8. A first gap 10 is present with the conical contact surface 80 of the hollow shank taper interface, and a second gap 11 is present with the flat contact surface 81 of the hollow shank taper interface. Thus, the front spindle 50 is centered only at the second centering interface 7 and clamped to the neck 56 by means of the clamping set 8. The first centering interface 6 is inoperative in this case.

[0050] As can be further seen from Fig. 4, the second centering interface 7 and the clamping point on the clamping set 8 are arranged in a common plane E. The plane E intersects the conical contact surface 80 on the hollow spindle shaft 3. Thus, the first centering interface 6 and the second centering interface 7 lie in a common plane E.

[0051] In Fig. 5, a tool holder 51 for holding a turning tool is shown as the tool receiving element 5. The tool holder 51, like the auxiliary spindle 50, is clamped via the clamping set 8 and is centered only via the second centering interface 7. The first centering interface 6 is not functional. Since relatively high forces and moments must be transmitted with turning tools, machining accuracy is considerably better if the turning tool is supported on the spindle housing 4 and not on the spindle shaft 3 at the first centering interface 6. According to the invention, different machining devices can thus be clamped to a main spindle 2 by means of the clamping set 8 and centered via the first centering interface 6 or the second centering interface 7. The possible uses of the main spindle can thus be significantly expanded.In particular, an auxiliary spindle 50 can be securely clamped and centered and driven at significantly higher speeds than the main spindle 2. Nevertheless, the main spindle according to the invention, as shown in Fig. 6, can clamp the standard tool holders 100 and center them at the first centering interface 6. Thus, the variability of the main spindle 2 can be significantly increased by providing the second centering interface 7 and using the single clamping set 8 in conjunction with either the first centering interface 6 or the second centering interface 7. A standardized clamping set 8, such as that provided for a hollow shank taper interface, can be used.

[0052] Thus, the variability of the main spindle 2 can be significantly improved by an additional centering interface 7.

[0053] List of reference symbols

[0054] 1 spindle arrangement

[0055] 2 main spindle

[0056] 2a Front side of the main spindle

[0057] 3 spindle shaft

[0058] 4 spindle housings

[0059] 5 Tool holder element

[0060] 6 first centering interface

[0061] 7 second centering interface

[0062] 8 Clamping set of an HSK connection

[0063] 9 Support device

[0064] 10 first gap

[0065] 11 second gap

[0066] 12 spindle nut

[0067] 13 Labyrinth seal

[0068] 20 Main spindle drive

[0069] 21 first bearing arrangement of the main spindle

[0070] 22 second bearing arrangement of the main spindle

[0071] 30 recesses

[0072] 31 external thread

[0073] 40 annular area

[0074] 50 front spindle

[0075] 51 tool holders

[0076] 52 Drive of the front spindle

[0077] 53 first bearing arrangement of the front spindle

[0078] 54 second bearing arrangement of the front spindle

[0079] 55 tools

[0080] 56 neck

[0081] 57 flat surfaces 70 webs

[0082] 71 grooves

[0083] 72 connections

[0084] 73 flat surfaces 80 conical contact surface of the HSK interface

[0085] 81 Plan layout of the HSK interface

[0086] 90 pens

[0087] 91 springs

[0088] 100 Tool holder 101 Tool

[0089] D1 first diameter

[0090] D2 second diameter

[0091] E Level

[0092] XX Spindle axis

Claims

Claims 1. Spindle assembly of a machine tool, comprising: - a main spindle (2) with a spindle shaft (3), a spindle housing (4) and exactly one clamping set (8), - a first centering interface (6) on the spindle shaft (3) and - a second centering interface (7) on the spindle housing (4), - wherein the first centering interface (6) is configured to provide a first centering between the spindle shaft (3) and a tool holder (100), wherein the clamping set (8) clamps the tool holder (100) and - wherein the second centering interface (7) is configured to provide a second centering between the spindle housing (4) and a tool receiving element (5), wherein the clamping set (8) clamps the tool receiving element (5) such that a gap (10,11) remains at the first centering interface (6).

2. Spindle arrangement according to claim 1, wherein the first centering interface (6) is designed as a hollow shaft cone interface.

3. Spindle arrangement according to claim 2, wherein the tool receiving element (5) is designed in the region of the first centering interface (6) such that in the clamped state of the tool receiving element (5) a first gap (10) is formed on a conical contact surface (80) of the hollow shaft taper interface between the spindle shaft (3) and the tool receiving element (5) and / or a second gap (11) is formed on a planar contact surface (81) of the hollow shaft taper interface between the spindle shaft (3) and the tool receiving element (5).

4. Spindle arrangement according to one of the preceding claims, wherein the second Centering interface (7) is arranged on an end face (2a) of the main spindle (2).

5. Spindle arrangement according to one of the preceding claims, wherein the second Centering interface (7) is arranged on an annular region (40) of the spindle housing (4), in particular adjacent to the spindle shaft (3) or adjacent to a labyrinth seal (13).

6. Spindle arrangement according to claim 5, wherein a plurality of connections (72) for power lines and / or signal lines and / or media channels are arranged on the annular region (40) of the spindle housing (4).

7. Spindle arrangement according to one of the preceding claims, wherein the second centering interface (7) has centering elements which provide a positive connection between the main spindle (2) and the tool receiving element (5).

8. Spindle arrangement according to claim 7, wherein the centering elements comprise webs (70) and grooves (71), in particular each with conical contact surfaces.

9. Spindle arrangement according to claim 8, wherein the webs (70) extend in the radial direction to a spindle axis (XX).

10. Spindle arrangement according to one of claims 7 to 9, wherein the second centering interface (7) further comprises, as centering elements, planar surfaces (73) for axial engagement between the main spindle (2) and the tool receiving element (5).

11. Spindle arrangement according to one of claims 7 to 10, wherein the centering elements are arranged in the circumferential direction at positions spaced equally from one another, in particular four centering elements are arranged at positions spaced 90° from one another.

12. Spindle arrangement according to one of claims 5 to 11, wherein the centering elements are arranged in the annular region (40) of the spindle housing (4).

13. Spindle assembly according to one of the preceding claims, further comprising an activatable support device (9) which establishes and releases a connection between the spindle housing (4) of the main spindle (2) and the spindle shaft (3).

14. Spindle assembly according to claim 13, wherein the support device (9) comprises pins (90) and Springs (91), wherein the springs (91) preload the pins (90) in a retracted position such that no connection is formed between the spindle housing (4) of the main spindle (2) and the spindle shaft (3).

15. Spindle arrangement according to claim 13 or 14, wherein the support device (9) engages in a recess (30) formed in the spindle shaft (3) or wherein the support device (9) is extendable in front of a shoulder on the spindle shaft (3).

16. Spindle arrangement according to one of the preceding claims, wherein the first centering interface (6) and the second centering interface (7) lie in a common plane E.

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