Machine tool with cooling device

Abstract

The present invention relates to a machine tool (1) including a rotary table (2) having a table plane (T) and rotatable around a rotation axis (XX). The machine tool (1) further includes a bearing (3) for mounting the rotary table (2) to a housing (4), and a cooling device (5) having a cooling passage (51) configured to allow a coolant to circulate therethrough. In this case, a gap (6) exists between the cooling device (5) and the rotary table (2) to ensure the rotatability of the rotary table (2). The machine tool is characterized in that the cooling device (5) is arranged between the table plane (T) and a bearing plane (L) extending through the center of the bearing (3).

Description

[Technical Field]

[0001] The present invention relates to a machine tool equipped with a cooling device. [Background technology]

[0002] In the machine tool industry, there has been a long-standing trend towards shorter machining times. This situation has resulted in high-speed machining and ever-faster machining processes. At the same time, it is desirable to improve the machining accuracy of the workpiece. However, high machining speeds lead to increased heating of the workpiece and machine parts. The resulting heating of the parts can lead to uncontrolled lengthening and warping, which has a negative impact on machining quality.

[0003] The rotary table receives the workpiece and allows it to be machined from different sides. During machining of the workpiece, the rotary table's bearings as well as its drive are subject to heat, particularly due to friction. Due to direct contact with the workpiece, the heat can be transferred to the workpiece via the table. In this case, the heating of the rotary table has a negative effect on the machining accuracy of the machine tool. Summary of the Invention [Problem to be solved by the invention]

[0004] The object of the present invention is to develop a machine tool having a rotary table and a cooling device for controlling the temperature of the rotary table and keeping it as constant as possible. Furthermore, the machine tool with the cooling device should be as simple and cost-effective as possible to manufacture. [Means for solving the problem]

[0005] This object is achieved by a machine tool having the features of claim 1.

[0006] The machine tool according to the present invention, characterized by claim 1, has the advantage that the cooling device is properly arranged between the machine tool bearing, which rotatably mounts the rotary table in the housing, and the table plane T of the rotary table. Furthermore, the cooling device is arranged directly adjacent to the rotary table, separated from it by a small gap. This allows the cooling device to dissipate heat as much as possible from both the area of ​​the table plane of the rotary table and the bearing, ensuring a defined temperature and improved machining accuracy of the rotary table due to reduced thermal expansion and warpage. In this case, the cooling device is a component with an integrated cooling channel configured to circulate a coolant therethrough. The modular design of the cooling device means that it can be easily manufactured and integrated into the machine tool. Therefore, it is not necessary to integrate the cooling channel in a complex manner into the rotary table or the housing that receives the rotary table. A costly seal between the rotary table and the housing is also omitted.

[0007] The dependent claims disclose preferred developments of the invention.

[0008] The gap preferably has a first gap region on a first side of the cooling device and a second gap region on a second side of the cooling device. In this case, the first side of the cooling device is arranged parallel to the table plane in the direction of the turntable, and the second side is preferably oriented radially inward from the cooling device in the direction of the rotation axis XX. This allows at least two of the four sides of the cooling device to contribute to cooling the turntable, so that the cooling device can efficiently dissipate heat from the turntable despite the gap.

[0009] More preferably, the cooling device is configured to cool the housing at a third side. In this case, the third side is preferably arranged parallel to the table plane between the cooling device and the housing. Furthermore, the housing and the cooling device are directly adjacent to each other at the third side. The housing absorbs heat from the bearing and the drive unit. The cooling device and the housing are directly adjacent to each other via the third side, which provides good thermal conduction between the housing and the cooling device, resulting in efficient heat dissipation from the housing, and preferably has fewer sides of the cooling device extending along the housing than along the turntable.

[0010] According to a further preferred embodiment of the present invention, the cooling device comprises a body and a cover, and the cooling passage is formed inside the body. In this case, the cover preferably closes the cooling passage towards the outside. The two-part structure means that the cooling device can be easily manufactured. In this case, the cooling passage is preferably formed to be open in the body so that it can be easily manufactured. The two-part structure consisting of the body and the cover also makes it easy to maintain the cooling device. The cover and the body are preferably made of a material with high thermal conductivity.

[0011] Preferably, the second gap region between the cooling body and the turntable has a stepped shape, which increases the heat exchange surface between the two parts and thereby allows for better dissipation of heat from the turntable. In this case, the respective steps of the turntable and the cooling device can be easily manufactured, for example by machining on a lathe.

[0012] More preferably, the gap has a contact seal. During machining, a cooling lubricant is introduced into the working chamber of the machine tool, generating a large amount of chips and other particles, which are carried away by the cooling lubricant. It is essential to prevent the cooling lubricant and other particles from entering the gap between the housing and the rotary table, as they can damage bearings and other components. The contact seal reliably prevents the cooling lubricant and particles from entering the gap between the rotary table and the frame. Since additional heat is generated from friction at the contact seal, it is preferably located in the gap area between the rotary table and the cooling device. This allows the cooling device to directly dissipate the frictional heat from the contact seal. The contact seal can be, for example, a lip seal.

[0013] Particularly advantageously, the contact seal is arranged in the first gap region between the cooling device and the turntable, whereby the contact seal is arranged particularly close to the opening of the gap towards the working chamber, so that the unsealed gap region is as small as possible.

[0014] According to a further preferred embodiment of the present invention, a labyrinth seal is disposed between the cooling device and the rotary table in the first gap region. The labyrinth seal also prevents the intrusion of cooling lubricant and other particles into the gap between the rotation axis and the housing. In this case, there is no direct contact between the cooling device and the rotary table. The high specific surface area means that heat can be efficiently dissipated from the rotary table to the cooling device through the labyrinth seal. Due to the narrow tolerances in the gap region, labyrinth seals cannot be used effectively in the case of varying temperature gradients between the sealing partners. By installing the labyrinth seal in the first gap region between the rotary table and the cooling device, efficient sealing of the gap at a controlled temperature is possible.

[0015] In this case, the labyrinth seal is preferably formed only by the protruding annular flange of the cooling device and the groove in the turntable. The labyrinth seal formed by the groove in the turntable and the annular flange of the cooling device allows for simple production. The heat transfer from the turntable to the cooling device is improved by the surface of the cooling device and the turntable in the first gap area enlarged by the labyrinth seal.

[0016] More preferably, the cooling device is provided with a dust-catching groove on its exterior. The dust-catching groove is configured to prevent the cooling lubricant from approaching the gap opening. This is preferably achieved by a groove in the cooling device whose radially inner surface is positioned closer to the rotation axis XX in the direction of the working chamber than the gap opening. This provides a shoulder that prevents the cooling lubricant and particles from directly penetrating the gap. In this case, the gap opening is preferably oriented perpendicular to the table plane T so that the cooling lubricant and particles can overcome gravity to enter the gap.

[0017] The dust catch groove is preferably the only area of ​​the cooling device that is in direct contact with the working chamber of the machine tool, leaving the remaining areas in contact with the housing or with the rotary table via a gap to contribute to heat dissipation.

[0018] The cooling device is preferably fixed to the housing via a threaded connection, which in this case fastens the cover to the body and the body to the housing. The threaded connection can be easily and cost-effectively integrated into the housing. Furthermore, the threaded connection allows for simple installation and removal of the cooling device. Screws made of a material with good thermal conductivity can improve heat transfer between the housing and the cooling device.

[0019] More preferably, the gap is less than or equal to 1 mm, in particular less than or equal to 0.3 mm. A small gap improves the thermal conduction between the turntable and the cooling device, which is made possible by temperature regulation using the cooling device, thereby allowing for tighter tolerances due to reduced thermal expansion.

[0020] According to a further preferred embodiment of the invention, the cooling device adjoins the inner ring of the bearing in an at least partial overlapping manner in the direction of the rotation axis XX. In this case, the cooling device is separated from the inner ring by a second gap region. The overlapping arrangement still allows the cooling device to dissipate heat from the inner ring of the bearing. The arrangement according to the invention therefore allows heat to be dissipated directly from the heat source, so that less heat is transferred to the rotary table.

[0021] Further details, advantages and features of the invention will become apparent from the following description of embodiments with reference to the drawings. [Brief explanation of the drawings]

[0022] [Figure 1] FIG. 1 is a schematic cross-sectional view of a detail of a machine tool in the region of a rotary table according to a preferred embodiment. [Figure 2] FIG. 2 is a schematic detail view of the machine tool in the region of the cooling device according to a preferred embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0023] Hereinafter, a machine tool 1 according to a preferred embodiment of the present invention will be described in detail with reference to FIGS.

[0024] The machine tool 1 comprises a rotary table 2 which is a rotationally symmetrical component and which is configured to rotate about a rotation axis XX. The rotary table is connected to a housing 4 via a bearing 3. The housing 4 is configured as the C-axis of the machine tool 1.

[0025] A table surface 22 having a flat table plane T is attached via a threaded connection to the rotary table 2 at a first end along the rotation axis XX. The table surface 22 is configured to receive a workpiece to be machined using the machine tool 1. Alternatively, the rotary table 2 can be configured in one piece with an integral table surface 22.

[0026] The turntable 2 is connected to a housing 4 via a bearing 3. Furthermore, a cooling device 5 is arranged between a bearing plane L extending through the center of the bearing 3 and a table plane T. The cooling device 5 extends in an annular shape around the rotation axis XX of the turntable 2. In this case, a gap 6 exists between the turntable 2 and the cooling device 5, and this gap ensures the rotatability of the turntable 2.

[0027] The bearing 3 is composed of an inner ring 31, an outer ring 32, and cylindrical rollers 33. In this embodiment, the bearing 3 is configured as an axial / radial cylindrical roller bearing. Thanks to the axial and radial orientation of the cylindrical rollers 33, the bearing 3 is characterized by very high strength and tilt stability, and achieves high precision in axial and radial relief. The inner ring 31, connected to the rotary table 2, is formed in two parts and has a C-shaped cross section that axially surrounds the outer ring 32. The outer ring 32 is fastened to the housing 4 via a threaded connection. Depending on the required profile, the bearing 3 may also be configured in other ways.

[0028] The turntable 2 is directly driven electrically. For this purpose, a rotor 23 is mounted below the bearing 3 of the turntable 2, towards the second end of the rotation axis XX, opposite the table plane. A stator 41 is mounted on the rotor 23 in the housing 4 with a circumferential gap 6, which drives the rotor 23 electromechanically. Alternatively, a direct mechanical drive of the turntable 2, for example via a transmission, is also conceivable. In particular, the electrically driven stator 41 preferably has an independent cooling device.

[0029] The cooling device 5 of Figure 1 is shown in detail in Figure 2. It is arranged in the housing 4 adjacent to the table surface 22. The cooling device 5 has a first side 5a oriented parallel to the table plane T in the direction of the first gap region 6a, and a second side 5b extending parallel to the rotation axis XX and oriented in the direction of the second gap region 6b. A third side 5c extends parallel to the table plane T and is oriented in the direction of the housing 4. A final, fourth side 5d extends parallel to the rotation axis XX and is oriented radially outward.

[0030] At the second side 5b, the cooling device 5 has two steps that enlarge the heat exchange surface. The corresponding step structure at the turntable 2 forms a second gap region 6b having a stepped shape. The step structure may also have three or more steps. The surface-enlarging structure at the second gap region 6b may have other shapes, such as a wave shape. To further increase heat exchange, the cooling device 5 and the turntable 2 may have a surface-enlarging structure at the first gap region 6a.

[0031] The cooling device 5 is composed of a body 52 and a cover 53. In this case, the cover 53 is connected to the body 52 via a screw connection 9. The screw connection 9 further fastens the body 52 to the housing 4 via the third side 5c in a threaded hole. In this case, the body 52 rests flush on the housing 4.

[0032] The screw heads are recessed in the cover 53 so that the threaded connection 9 does not affect the first gap region 6a. Alternatively, the cooling device 5 may be, for example, welded, soldered, crimped or glued to the housing 4. The cooling device 5 may also be configured without the cover 53, for example as a cast or additively manufactured part with integrated cooling channels 51.

[0033] The first cooling passage 51a and the second cooling passage 51b are integrated into the main body 52. ​​The first cooling passage 51a is disposed closer to the rotation axis XX than the second cooling passage 51b. In this case, preferably, the first cooling passage 51a is a flow passage, and the second cooling passage 51b is a return passage.

[0034] The cooling channel 51 may consist of only a single channel in the cooling device 5 or may consist of several channels. In FIGS. 1 and 2, the cooling channel 51 is rectangular, which allows for simple production. Alternatively, the cooling channel 51 may have any other shape. A fluid flows through the cooling channel 51, which may be, for example, water or a special cooling fluid. In this case, the cooling channel 51 should, on the one hand, have as large a contact surface as possible with the body 52 of the cooling device 5 to enable a high level of heat exchange, and, on the other hand, the pressure loss along the cooling channel 51 should be as small as possible. Turbulent flow guidance through the cooling channel 51 allows for a rapid uptake of thermal energy into the fluid flowing in the cooling channel 51.

[0035] Two contact seals 7 are integrated into grooves in the cover 53 to the left and right of the screw connection, which seals are configured as lip seals. The contact seals 7 rest on the table surface 22 of the turntable 2 and seal the first gap area 6a against the working chamber 10. The contact seals 7 may also be mounted in grooves in the turntable 2 or the table surface 22 and rest against the cooling device 5. Depending on the sealing requirements, it is also possible to integrate only one or more lip seals into the gap 6.

[0036] In this embodiment of the invention, the body has a dust-catching groove 54 on the fourth side 5d, which groove is adjacent to the work chamber 10. The purpose of the dust-catching groove 54 is to keep particles away from the work chamber during machining and to keep the cooling lubricant away from the opening of the gap 61. This is achieved by a notch, which acts as a shoulder for the opening of the gap 61 so that particles and the cooling lubricant are not directly introduced into the opening of the gap 61. In this case, the opening of the gap 61 opens into the dust-catching groove 54 perpendicular to the table plane T. Furthermore, a groove 21 is provided in the table surface 22, which forms a U-shaped gap. Analogous to the groove 21, the cooling device 5 has an annular flange 55.

[0037] Thus, a labyrinth seal 8 is formed in the first gap region 6a by the groove 21 and the annular flange 55 immediately behind the opening of the gap 61, which labyrinth seal further prevents the ingress of dust.

[0038] The machine tool 1 therefore comprises a turntable 2 and a cooling device 5 which controls the temperature of the turntable 2 and keeps it as constant as possible. Furthermore, the machine tool 1 including the cooling device 5 is simple and cost-effective to manufacture.

[0039] In addition to the above description of the invention, and for further disclosure thereof, reference is now expressly made to exemplary drawings of the invention in FIGS. [Explanation of symbols]

[0040] 1 Machine tools 2 Rotating Tables 3. Bearings 4. Housing 5 Cooling device 5a First side 5b Second side 5c Third side 5d Fourth side 6 Gap 6a First gap area 6b Second gap area 7 Contact seal 8 Labyrinth Seal 9 Threaded Connection 10 Workroom 21 Groove 22 Table surface 23 rotor 31 Inner ring 32 outer ring 33 Cylindrical roller 41 Stator 51 Cooling path 51a First cooling path 51b Second cooling path 52 Main Unit 53 Cover 54 Dust capture groove 55 Annular flange 61 Gap opening L bearing plane T table plane XX Rotation axis

Claims

1. a rotary table (2) having a table plane (T) and rotatable about a rotation axis (X-X); a bearing (3) for mounting the rotary table (2) to a housing (4); a cooling device (5) having a cooling passage (51) configured to allow a coolant to flow therethrough; A gap (6) exists between the cooling device (5) and the turntable (2) to ensure the rotatability of the turntable (2), The cooling device (5) is arranged between the table plane (T) and a bearing plane (L) extending through the center of the bearing (3).

2. 2. The machine tool (1) according to claim 1, wherein the gap (6) comprises a first gap region (6a) on a first side (5a) of the cooling device (5) and a second gap region (6b) on a second side (5b) of the cooling device (5).

3. 3. The machine tool (1) according to claim 2, wherein the cooling device (5) is configured to cool the housing (4) at a third side (5c).

4. The machine tool (1) according to any one of claims 1 to 3, wherein the cooling device (5) comprises a main body (52) in which the cooling passage (51) is formed, and a cover (53).

5. The machine tool (1) according to any one of claims 2 to 4, wherein the second gap region (6b) is configured to have a stepped shape.

6. The machine tool (1) according to any one of claims 1 to 5, wherein a contact seal (7) is arranged in the gap (6).

7. 7. The machine tool (1) according to claim 6, wherein the contact seal (7) is arranged in the first gap region (6a).

8. The machine tool (1) according to any one of claims 2 to 7, wherein a labyrinth seal (8) is arranged in the first gap region (6a).

9. 9. The machine tool (1) according to claim 8, wherein the labyrinth seal (8) is formed by a protruding annular flange (55) of the cooling device (5) and a groove (21) in the rotary table (2).

10. The machine tool (1) according to any one of the preceding claims, wherein the cooling device (5) is provided with dust-catching grooves (54) on the outside.

11. 11. Machine tool (1) according to claim 10, wherein the cooling device (5) is in direct contact with the working chamber (10) of the machine tool (1) only at the dust catch groove (54).

12. The cover (53) is fixed to the body (52) by a screw connection (9), Machine tool (1) according to any one of claims 4 to 11, wherein the threaded connection (9) also secures the body (52) in the housing (4).

13. Machine tool (1) according to any one of the preceding claims, wherein the gap (6) is less than or equal to 1 mm.

14. 14. The machine tool according to any one of claims 1 to 13, wherein the cooling device (5) adjoins the inner ring (31) of the bearing (3) in an overlapping manner at least partially in the direction of the rotation axis (X-X).

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