Machine tool with variable bearing prestress

Abstract

The invention relates to a machine tool (1) having an axial-radial bearing (2) for absorbing forces and moments between an outer ring (5), an inner ring (4) and a shaft disk (6) fastened thereto, in order to support a rotating shaft for rotating a tool or a workpiece during operation, a pressure chamber (12) filled with a fluid being provided and arranged such that the pressure chamber (12) is in fluid communication with the outer ring (5), the inner ring (4), and the shaft disk (6) fastened thereto, and the pressure chamber (12) being in fluid communication with the outer ring (5), the inner ring (4), and the shaft disk (6) being in fluid communication with the inner ring (4). In this way, the prestress in the bearing (2) is increased when the pressure chamber (12) is filled with fluid.

Description

Technical Field

[0001] This invention relates to a machine tool with high machining speed for five-axis linkage machining, the machine tool having an axial-radial bearing designed as a rolling bearing, the axial-radial bearing being suitable for absorbing forces in the radial direction and absorbing pressure and tension in the axial direction, absorbing forces and torques between the outer ring, the inner ring and the shaft disc fixed on the inner ring, for supporting a rotating shaft used to rotate a tool or workpiece during operation. Background Technology

[0002] In machine tools, units such as milling heads, machining heads, rotary axes, and rotary tables serve as tools and manufacturing aids, enabling the machining of workpieces with high speed and precision in complex geometries and the fabrication of component parts into complete units. The tools used for the corresponding workpieces typically vary depending on the type of machine tool. Thus, machine tools can be implemented, for example, as milling machines or lathes. A characteristic of machine tools is that the tool and / or workpiece perform relative motion with each other. Regarding the relative motion of the tool and workpiece, it is necessary to distinguish, in principle, the machining strategy for a stationary tool or workpiece and the machining strategy for a workpiece or tool moving relative to it. The relative motion of the tool and workpiece, and the rotary table carrying the workpiece, is generally achieved via rotary axes.

[0003] Here, a fundamental prerequisite for the quality of the manufactured workpiece in terms of achievable machining accuracy is that the workpiece, tools, and other manufacturing aids, such as those obtained through CNC machining strategies, precisely occupy and maintain their predetermined positions. Due to the high machining forces and torques generated during machining, such as the milling head or rotary table and the rotary axes guiding it, which must withstand alternating and varying magnitudes of machining forces and torques, large relative movements are not permitted. Furthermore, the high variability achievable by machine tools, particularly through 5-axis machining, and the numerous possible machining strategies resulting from this flexibility (including positional variations in tool and workpiece orientation), place even higher demands on the positioning accuracy of the specific rotary axes, which form the basis for maintaining the required machine tool operating accuracy.

[0004] To meet the requirements of high position stability and positioning accuracy, different strategies were studied.

[0005] Therefore, in combined machining (all axes meshing, axes moving relative to each other, and synchronous interpolation), the drive generates a tangential torque to maintain the position of the driven components of the machine tool. However, this torque is insufficient for many processes, so the rotary / rotary axis is secured by a clamping device after positioning. Here, the clamping device does not absorb kinetic energy, and therefore does not involve braking. Instead, the clamping device generates a position-stabilizing tangential resistance torque. Similarly, bearings, and especially axial-radial bearings, are used in guiding and supporting the rotary / rotary axis. Axial-radial bearings are technically designed here to absorb gravity and tilting torques and are suitable for use at very high limiting speeds. Here, the bearing type has very high stiffness and a low uniform frictional torque profile while maintaining high tilting stiffness. By adjusting the bearing prestress, the magnitude of the absorbable force and torque can be adjusted within a predetermined limit according to, for example, the corresponding machining strategy or the specific material and its material properties.

[0006] To ensure stable tangential resistance torque, the clamping device, possibly the bearings, and the rotating worktable must be precisely coordinated with each other. This includes the ability to set and substitute for the clamping device with prestress in the axial or radial direction (axial prestress / radial prestress).

[0007] The limit of prestress for increasing the prestress of bearings used in rotating shafts / rotating shafts is described here by the maximum adjustable stiffness of a particular bearing. If the prestress exceeds a specific value for the bearing, only a slight increase in bearing stiffness is possible, while friction and heat within the bearing increase, which can, to varying degrees, cause bearing damage. Increasing prestress by introducing adjusting shims or spacers through a path that enhances the bearing prestress in industrial environments, using preload and bearing elastic deformation / deformation, is widely applied.

[0008] Prior art for spindle prestressing in machine tools is known according to document US 3620586A. This invention provides a spindle support for a machine tool, suitable for applying a predetermined small prestress to the spindle bearing during high-speed operation and a predetermined higher prestress during low-speed operation. The prestressing mechanism includes a pair of axially oriented, hydraulically operated pistons arranged on opposite sides of one of the outer bearing rings. The pistons have a relatively narrow annular shape and do not protrude significantly radially above the bearing, thereby minimizing the space required in the spindle housing. Each spindle bearing has an annular groove on its outer circumference, through which coolant can circulate for more efficient cooling of the bearing. These cooling grooves also allow the bearing to be directly mounted into the spindle housing without needing to be mounted in a cooling sleeve located between them, thereby achieving more precise spindle support.

[0009] Clamping devices can be implemented as hydraulic, pneumatic, spring-loaded, or electromechanical. Important criteria here are the preferred degrees of freedom for positional accuracy and high tangential resistance torque. Hydraulic clamping devices have already established themselves in the market for larger hole diameters. Only a few solution providers, such as Zimmer and Kostyrka, or many rotary table manufacturers offer their own solutions. Typically, bearings have a predetermined prestress due to their structure. However, this prestress cannot be changed. Currently, clamping devices exist that fix the rotary axis tangentially only. This is advantageous for 5-axis machining.

[0010] However, this reaches the technical limit in 5-axis simultaneous machining. Current technology is a compromise between bearing prestressing and position adjustment in so-called torque motors or master-slave or gantry operation modes in gearboxes.

[0011] Therefore, the ability to adjust bearing prestress dynamically or in a variable manner depending on the selected processing strategy is desirable. Furthermore, reducing mechanical interfaces and installation workload is beneficial, which can lower costs.

[0012] When machining materials that are difficult to cut, prestressing one of the bearings that guide the rotating shaft / rotation shaft can have a beneficial effect on the stability of the rotating shaft and the machining accuracy. Summary of the Invention

[0013] In this context, the object of the present invention is to avoid or at least minimize the disadvantages known in the prior art.

[0014] This is achieved for this type of tool by filling the pressure chamber with fluid and arranging the pressure chamber in a way that increases the prestress in the bearing when the pressure chamber is filled with fluid.

[0015] It can be said that the machine tool has at least one bearing equipped with variable prestress, which is configured to change the value of the prestress to a value different from the original / initial prestress value, or to change the value of the prestress to a value equivalent to the original / initial prestress value when, for example, the prestress in the bearing decreases due to thermal expansion or expansion gradient of the machine tool parts during operation, and especially at least one or more bearings and the rotating shaft guided by them. Here, the prestress is used to fix the rotating shaft of the machine tool and to fix the rotating shaft in its position during the operation of the machine tool. The rotating shaft is used to guide and support parts such as rotating worktables, milling heads, spindles, etc. Here, increasing the prestress in one or more bearings of the machine tool is a technical measure that at least supplements or replaces the prior art for fixing the position of the rotating shaft. In this way, the clamping force acting on the rotating shaft via a clamping device, such as a sleeve, or the tangential torque generated by the drive unit that acts opposite to the running force and torque, or the control of the adjustment position of the transmission and drive unit, is supplemented.

[0016] Therefore, the solution of the present invention can be summarized as follows: variable prestress is introduced into the machine tool via bearings, and the design involves adjusting the clamping torque provided in the machine tool to fix and secure the shaft. According to the present invention, the pressure chamber is a central technical component of the machine tool for changing the prestress on one or more bearings.

[0017] Advantageous embodiments are set forth in the dependent claims and explained in detail below.

[0018] Pressure chambers can be designed to contain liquids such as oil or gaseous working media such as air, compressed air, or aerosols for hydraulic or pneumatic activation. This design of the pressure chamber allows for the advantageous filling of the pressure chamber with oil or other working media via a pressure loading and supply system, preferably not located in the bearing and preferably pneumatic or hydraulic. The connection between the supply system and the corresponding pressure chamber is advantageously achieved via pressure lines. Here, the pressure chamber can preferably be integrated into batches of bearing parts by machining or by simply integrating it during the manufacturing process of the bearing parts using casting or additive manufacturing techniques. An advantageous embodiment of the pressure chamber provides a surrounding pressure chamber, wherein it is also conceivable to distribute multiple pressure chambers circumferentially at predetermined intervals. In manufacturing the pressure chamber, care is preferably taken to make the walls of the pressure chamber sufficiently rigid or to surround the pressure chamber with such a large volume of material that the pressure chamber can withstand and completely absorb the pressure of the oil / other, especially gaseous, working media flowing into or within the pressure chamber. This principle applies whenever deformable or flexible walls of the pressure chamber are not required in the context of the invention. Areas with deformability or lower stiffness are important, as described in conjunction with other features of the following advantageous embodiments. The pressure chamber, technically implemented, advantageously has at least one wall with lower stiffness or an opening at at least one location preferably facing the bearing raceway. Further description of the advantageous embodiments will show advantageous configurations of such openings, which can be closed by form fit, material fit, or force fit.

[0019] As an embodiment of the aforementioned pressure chamber, oil / other, and especially gaseous, working media are advantageously contained within the pressure chamber for further, preferably, hydraulic or pneumatic activation. During the operation of the machine tool and throughout its service life, and especially under static forces and torques, such as dynamic loads, it is advantageous to ensure that oil / other, and especially gaseous, working media are contained through the pressure chamber.

[0020] In the illustrated invention, it is also advantageous that the pressure chamber is located within the inner or outer ring and is supplied with a working medium via a pressure line during operation to influence the pressure. By arranging the pressure chamber within the inner and outer rings of the bearing, structural freedom in bearing position is advantageously achieved. Furthermore, the positioning of the pressure chamber within the inner or outer ring allows it to influence different raceways of the bearing.

[0021] Furthermore, according to the invention, it is advantageous to provide a pressure line for supplying oil / other, and especially gaseous, working media to the pressure chamber, the pressure line enabling controlled inflow and outflow of the oil / other working media from the pressure chamber. Particularly advantageous in relation to the pressure line is the targeted adjustment of the volumetric flow / pressure of the oil / other working media in a predetermined manner. In addition to the achievable inflow, the outflow of the oil / other working media can also be advantageously achieved to adjust the preload according to the forces and torques occurring during operation (including their maximum and minimum values) and the changes in the spacing of individual bearing components / bearings due to thermal expansion gradients. It is also advantageous in relation to the pressure line to guide and protect it from the effects of forces and torques acting during operation. Advantageous designs for guiding include, for example, through holes or built-in channels in the material of the bearing components. When the guide portion of the pressure line is designed as a free conduit or free hose, it is advantageous to take care to protect the conduit from tearing due to forces and torques occurring during operation.

[0022] Furthermore, it is advantageous to provide an insert disc, an annular piston, or raised sections on the outer ring, inner ring, or shaft disc to apply pressure to the raceways of the axial-radial bearing. Starting from a pressure chamber with supplied oil / other working medium, pressure is applied to adjacent material areas via techniques such as an annular piston and / or an annular disc / insert disc or deformable material sections guided thereon or separately. In the illustrated embodiment of the pressure chamber, it is technically advantageous to change the position of the annular piston / annular disc due to the inflow of oil / other working medium, causing the annular piston / annular disc / insert disc to be pressed out / extruded from its original position and occupy an advantageously predetermined new position. This means that in this embodiment, the pressure chamber opens on the side facing the annular piston / annular disc / insert disc, allowing the annular piston / annular disc / insert disc to move out of the pressure chamber and relative to the inner surface of the outer ring / inner ring / shaft disc. This relative movement advantageously allows pressure to be applied to the surface of adjacent materials or parts via surface contact and preferably elastically deformed. Another advantageous embodiment is that no intermediate elements, such as annular pistons / annular discs / insertion discs, move due to the pressure of the flowing oil / other working medium; instead, the pressure acts directly on the walls of the pressure chamber, which have lower stiffness. In this embodiment, the lower stiffness is advantageously achieved by limiting the thickness of the material layer of the wall of the bearing / outer ring / inner ring / parts and the arrangement in the near-surface region. The lower stiffness and the advantageous elastic deformation capability resulting from the achieved thin material walls advantageously enable the wall bulging phenomenon known for the material diaphragm under pressure to be achieved. And because the wall bulging enables contact with the adjacent surface and allows it to deform elastically. For both embodiments, it is advantageous and in principle conceivable that this is achieved in the outer ring and / or inner ring and / or shaft ring of one or more bearings. Due to the bulging of the pressure chamber walls or the movement of the annular pistons / annular discs / insertion discs, the so-called envelope of the relevant rings is increased. The elastic deformation of the bearing raceways adjacent to the pressure chamber and provided on the respective adjacent surfaces is achieved in a technically advantageous manner by the elastic deformation of the surfaces of the respective envelopes of the adjacent rings. This means that the deformation caused by the pressure of the oil / other, especially gaseous, working medium is elastic and therefore reversible.

[0023] Furthermore, it is advantageous to use one or more seals to seal the pressure chamber. In this way, the pressure chamber can be sealed relative to the ambient medium and / or prevent oil / other working media located in the pressure chamber from flowing out. This embodiment advantageously maintains the pressure within the pressure chamber. This is a core prerequisite for the technical solution according to the invention.

[0024] Furthermore, the direction of movement of the annular piston, pressure plate, insertion plate, or raised section is precisely predetermined along the direction of the raceway. This embodiment advantageously prevents lateral forces, generated by the dispersion effect on the envelope area of ​​the raised wall of the annular piston / annular plate / insertion plate / pressure chamber, from appearing on the raceway. On the other hand, this embodiment enables uniform deformation of the raceway due to the central effect of deformation pressure. Since unpredictable lateral forces are eliminated, the prestress can be specifically adjusted to a predetermined value. The precise adjustability of the prestress is of particular technical significance here, as excessive prestress can cause irreversible bearing damage due to plastic deformation or increased friction and accompanying thermal damage. It is also advantageous to adjust minute variations in the prestress value, such as in relation to the thermal expansion gradient of the bearing and machine tool components during operation. This is disadvantageously difficult due to the lateral forces generated by the dispersion stress of the raceway. It has also proven advantageous in this respect that the adjusted prestress value can preferably be checked / verified by force, displacement, or friction value and suitable devices, and can be compared with the calculated value.

[0025] Another advantage is that the inner ring's bulging section is designed as a diaphragm. The low-stiffness and elastically deformable wall portion, designed as a diaphragm, allows this section to bulge significantly and easily under applied pressure, lower than the pressure required to bulge a thin wall via pressure loading preferably achieved hydraulically or pneumatically. Here, the diaphragm is advantageously designed to achieve the sealing function of the pressure chamber. Furthermore, it advantageously protects the diaphragm from damage during machine tool operation caused by, for example, forces, torques, media, and materials.

[0026] Furthermore, it has proven advantageous that the pressure chamber is sealed via a material connection between the ring and the inner ring that encloses the pressure chamber. This provides the above-described embodiment according to the invention, which provides elastic deformation due to the bulging thin walls of the pressure chamber or diaphragm. If, due to manufacturing limitations and considering cost and forces generated during operation, a narrow gap cannot be achieved in the thin-walled / diaphragm region, then it is necessary to introduce the pressure chamber into the ring by machining, seal the pressure chamber by the ring / pressure element, and weld the pressure element to the outer surface of the ring. Advantageously, the supply line for oil / other, and especially gaseous, working media can be achieved by guiding a supply line through the inner ring of the bearing.

[0027] Another advantage is that the position of the pressure plate, annular piston, insert plate, or raised material wall can be reversibly changed by the inflow of the working medium. Complete reversibility ensures that the machine tool bearings can return to their original state at any time. Furthermore, this embodiment allows for the calculation of the bearing prestress using a linear-elastic relationship based on elastic deformation, preferably pneumatic or hydraulic working medium pressure, and / or adjustment length and / or force assumptions, thereby reducing computational workload. Because the bearing is already prestressed in its original installation state, after a pressure drop, for example, the insert ring is pressed back to its initial position, and the original structural prestress is re-established.

[0028] In specific implementations, the inflow of the working medium can be selectively controlled to generate a predetermined prestress. This is advantageously predicated on the controllable inflow and outflow from the pressure chamber, allowing for the selective and variable adjustment of the bearing prestress using preferred fundamental physical and / or thermodynamic principles.

[0029] The present invention’s method for increasing prestress, as presented through a machine tool embodiment, can in principle be combined with other methods for fixing the position of a rotating shaft, such as a clamping device, a torque motor, or a master-slave control of a transmission or a position control mechanism / bearing adjustment mechanism in gantry operation.

[0030] The illustrated embodiments are generally applicable to axial bearings, axial-radial bearings, radial bearings, and combinations of axial and radial bearings. The type of prestress achieved (axial and / or radial prestress) is determined by the direction of motion and the direction of pressure application / envelope increase of the corresponding inventive scheme. The applicability of the present invention has proven advantageous for the following types of rotary table bearings: YRT (axial-radial (roller) bearings, bidirectional, screw-operated), YRTC (axial-radial bearings, bidirectional, screw-operated), YRTCMA (axial-radial bearings, bidirectional, screw-operated, with an integrated absolute angle measurement system), YRTCMI (axial / radial bearings, bidirectional, screw-operated, with an integrated incremental angle measurement ring / system), and YRTCG and YRTCGMA (such as YRTCG, with an integrated absolute angle measurement system). Attached Figure Description

[0031] The invention will now be described in detail with reference to the accompanying drawings. Two different embodiments of the invention are shown in detail here. The drawings are as follows:

[0032] Figure 1A partial cross-section of a rotationally symmetric axial-radial-rolling element bearing for the rotating shaft of a rotary table according to a first embodiment of a machine tool according to the invention is shown, wherein a hydraulically operated unit is provided in the outer ring of the bearing for increasing prestress, and

[0033] Figure 2 A partial cross-section of a rotationally symmetric axial-radial-rolling element bearing for a rotating table of a machine tool according to another embodiment of the invention is shown, wherein a hydraulically operated unit is provided in the inner ring of the bearing to enhance prestress. Detailed Implementation

[0034] The accompanying drawings are merely illustrative and intended only to illustrate the invention. Identical elements are given the same reference numerals. Features of the two embodiments can be substituted for each other or can complement each other.

[0035] Figure 1 A partial cross-section of a first embodiment of a rotationally symmetric axial-radial-rolling element bearing 2 for a rotating axis of a rotating worktable is shown for a machine tool 1 according to the invention. The axial-radial bearing 2, from bottom to top and in the axial direction in the drawing plane, consists of an inner ring 4, an outer ring 5, and a shaft ring 6. Each ring 4, 5, and 6 has an inner surface and an outer surface. The inner ring 4 and the shaft ring 6 are force-connected and form-fitted, and are configured in a C-shape. In this case, the area enclosed by the C-shape represents the inner surface / inner surface of the rings 4, 5, and 6. The outer surface 8 represents the outer region opposite to the inner surface.

[0036] The shaft ring 6 is placed on the inner ring 4. The inner ring 4 has two regions with different diameters. Referring to the plane of the drawing, there is a region with the smaller diameter / inner diameter of the inner ring 4 below the shaft ring 6 and adjacent to the shaft ring 6, followed by the lower region of the inner ring 4 with the larger diameter / outer diameter. From a structural point of view, a two-piece implementation of the inner ring 4 is conceivable in principle. The outer ring 5 is arranged between the shaft ring 6 and the lower region of the inner ring 4 with the larger diameter, and is spaced from the inner surface / inner surface 7 of the inner ring 4 and the shaft ring 6. The outer ring 5 has a surrounding surface 9. The contact between the inner surface / inner surface 7 of the inner ring 4 and the surfaces 9 of the inner ring 4 and the outer ring 5 is achieved via the raceway 10 of the axial-radial bearing 2 of the machine tool 1. Raceway 10 is positioned between the inner surface 7 of the bearing ring 6 and the bearing-side surface 9 of the outer ring 5, between the lower side of the outer ring 5 and the lower side of the inner ring 4 with a larger diameter region, and between the surface 9 of the outer ring 5 oriented radially toward the vertical wall portion of the inner ring 4 of the axial-radial-bearing 2 and the surrounding recess 11 provided in the wall portion of the inner ring 4. Raceway 10 includes rolling elements.

[0037] According to the invention, the outer ring 5 of the axial-radial bearing 2 includes a non-through recess, a so-called pressure chamber 12, the opening of which is located on the surface 9 of the outer ring 5 on the shaft side. The recess / pressure chamber 12 has a predetermined width dimension in the radial direction and a depth dimension in the axial direction, wherein this dimension is, in principle, variable. In the illustrated embodiment, the recess is sized to accommodate the annular disc 13 and the annular piston 14, as well as the sealing ring 15 and the discharge structure 16. A hydraulic supply line 17 is also provided, which guides the working medium, such as hydraulic oil or compressed air, through a manufacturing technique into the outer ring 5 and here into an annular region, preferably without a fixed hole. According to the invention, the recess / pressure chamber 12 filled with the working medium, such as hydraulic oil, is positioned relative to the environment via a surrounding sealing element, such as a sealing ring, and prevents the working medium from escaping from the recess. According to the embodiment, the sealing ring is arranged below the annular disc 13. To prevent oil leakage, the discharge structure 16 is implemented below the annular piston 14. The discharge structure 16 on the lower side of the insert ring / insert disc 13 ensures that no oil layer is formed. According to the invention, via a controlled inflow of a working medium, such as hydraulic oil, the annular piston 14, including the sealing ring 13, moves in the shaft ring side and axial direction until the sealing ring 13 occupies a predetermined position in the region of the shaft ring side surface 9 of the outer ring 5 or above the shaft ring side surface. According to the invention and according to embodiments, this is accompanied by an increase in the surface 9 of the outer ring 5, whereby the raceway 10 elastically deforms into a predetermined and calculated size. This elastic deformation alters and increases the initial prestress of the axial-radial bearing 2 of the machine tool 1 in the axial direction. By preferably reducing the volume and pressure of the working medium, such as hydraulic oil, the annular disc 13 moves in the axial direction from... Figure 1The position shown is moved above or below the currently occupied position to a position that can be adjusted in a targeted manner. In this way, the position of the annular disk 13, as well as the elastic deformation and prestress of the bearing 2, can be targeted within a predetermined range that determines the functionality of the bearing 2. Here, according to the invention, the elastic deformation of the axial-radial raceway 10 of the machine tool 1 and the bearing 2 is completely reversible, so there is no additional prestress on the bearing 2 defined by the invention for the position of the annular disk 13 below the axial-radial raceway 10 of the bearing 2 or on the plane of the surface 9 of the outer ring 5. According to the invention, this prestress can be adjusted according to the preferred machining force, thermal expansion during operation, or other factors applied by other technical means, such as clamping devices or drive units, tangential resistance torque, or control techniques, and the initial setting of the bearing 2. According to the invention, orientation and direction of movement can be changed. Therefore, the downward movement of the annular piston 14 and the annular disk 13 toward the lower raceway 10 of the inner ring 4 is conceivable as is the movement in the radial direction and the change / increase of radial prestress in the latter case. In addition to the annular piston 14 and annular disc 13, it is also conceivable to use elements movable by a working medium according to the invention. In principle, it is also conceivable that the invention is applicable to axial bearings or combinations of radial and axial supports with or without rolling element arrangements in the raceway 10. It can also be said that, regarding the outer ring 5 of the bearing 2, an advantageous embodiment can be summarized as follows: an insert ring / insert disc 13 is placed in the surrounding pressure chamber 12. Pressure is built between the outer ring 5 and the insert ring 13 via a hydraulic supply line 17. This causes the outer ring 5 and the insert ring / insert disc 13 to move away from each other. This increases the prestress in the axial direction of the bearing 2 in the machine tool 1.

[0038] exist Figure 2 The diagram shows machine tool 1 and... Figure 1 The bearing corresponding to the axial-radial bearing 2 described herein is shown, illustrating a second embodiment of the axial-radial bearing 2. A partial cross-section of a rotationally symmetric axial-radial bearing 2 for a machine tool according to the invention is also shown. However, compared to... Figure 1 Compared to the embodiments shown in the previous section, the illustrated embodiment according to the invention relates to the inner ring 4 and, in particular, to the region of the inner ring 4 having a larger diameter.

[0039] Screws 18 are preferably provided as connecting elements between the inner ring 4 and the shaft ring 6 arranged above it (see...). Figure 2However, in principle, other embodiments of the connecting element can also be realized based on this idea and the present invention. For positioning the screw 18, a hole 19 is shown in the axial direction, penetrating the inner ring 4 and the shaft ring 6 positioned thereon. The region of the inner ring 4 including the penetrating hole 19 is called the wall portion 20 of the axial-radial-rotational shaft side of the bearing 2. The hole 19 is implemented as a fixing hole. A countersunk hole 21 with a predetermined diameter and predetermined depth is provided on the upper side of the shaft ring to form-fit the head of the screw 18, thereby having a larger diameter in the region of the countersunk hole 21 than in the rest of the hole 19. For the entire bearing 2, a plurality of such individual holes 19 are arranged circumferentially at predetermined intervals. Similarly, penetrating fixing holes 22 are introduced circumferentially into the outer ring 5 at predetermined intervals to realize the fixing element and connection with other structural elements in the machine tool 1. A recess / pressure chamber 12 is provided below the raceway 10 for axial support, in which a ring / pressure element 23 is positioned. The ring / pressure element 23 is smaller in the axial direction than the notch / pressure chamber 12 and is material-joined and form-fitted onto the outer surface 8 of the inner ring 4. According to the illustrated embodiment, a weld is provided, which is implemented such that the outer surface 8 of the inner ring 4 / ring / pressure element 23 forms a plane. Due to the small axial dimension of the ring / pressure element 23, it is preferable to form a pressure chamber 12 that is essentially free in the sense of the pressure gap 24. The pressure gap 24 can be supplied with a working medium via a pressure conduit 17 through a pressure inlet 25, wherein the working medium is preferably hydraulic fluid or compressed air, which can be introduced into the pressure gap 24 under pressure. Preferably, and according to the invention, the weld 26 of the ring / pressure element 23 seals the pressure gap 24 relative to other ambient media and prevents loss of the working medium. A maximum size of 0.5 mm has proven technically advantageous for the size of the pressure gap 25. The pressure gap 24 is very close to the inner surface 7 of the inner ring 4 below the raceway 10 in this region, making the area of ​​the inner ring 4 adjacent to the raceway 10 very narrow in the axial direction. Due to the narrowness of the pressure gap 24, the pressure of the working medium causes the elastic bulge of the section 27 of the inner ring 4, thereby increasing the envelope of the inner ring 4 and causing elastic deformation of the adjacent raceway 10, while simultaneously increasing the preferred axial prestress of the bearing 2 according to the invention. Alternative arrangements and directions of movement of the elements, as well as the use of technically comparable elements, are also conceivable and feasible in principle.

[0040] In studying the implementation method, it is important to understand that a pressure gap 24, in the sense of a pressure chamber 12, is achieved in the inner ring 4 of the bearing 2. Pressure is supplied to the pressure chamber via a hydraulic line 25, and a ring / pressure element 23 is placed into the pressure chamber. In principle, the pressure element can be pneumatically controlled. The pressure chamber 12 is sealed by a material connection. Prestress is increased by increasing the oil pressure.

[0041] List of reference numerals

[0042] 1 Machine tool

[0043] 2 Axial-Radial-Bearings

[0044] 3 Rotation axis

[0045] 4 Inner ring

[0046] 5 Outer ring

[0047] 6-axis ring

[0048] 7. Inner surface

[0049] 8. Outer surface

[0050] 9. Surface on the side of the shaft ring

[0051] 10 raceways

[0052] 11 Notch

[0053] 12 pressure chambers

[0054] 13. Circular disc / insertion disc

[0055] 14. Annular Piston

[0056] 15. Seals

[0057] 16. Emission Structure

[0058] 17 Supply / pressure lines for oil / other, and especially gaseous, working media.

[0059] 18 screws

[0060] 19 holes

[0061] 20 Wall section

[0062] 21 Countersunk Hole

[0063] 22 Fixing holes

[0064] 23 rings / pressure elements

[0065] 24 Pressure gap

[0066] 25 Pressure Inlet

[0067] 26 Welding Section

[0068] 27. Raised section / material wall / section

Claims

1. A machine tool (1) having an axial-radial bearing (2), said axial-radial bearing (2) for absorbing forces and torques between an outer ring (5), an inner ring (4) and a shaft disc (6) fixed on said inner ring (4) to support a rotating shaft (3) for rotating a tool or workpiece during operation, characterized in that, The axial-radial bearing (2) is provided with a pressure chamber (12) filled with fluid, and the pressure chamber (12) is arranged such that the prestress in the bearing (2) is increased when the pressure chamber (12) is filled with fluid.

2. The machine tool (1) according to claim 1, characterized in that, The pressure chamber (12) is designed to contain a liquid or gaseous working medium for hydraulic or pneumatic activation of the pressure chamber (12).

3. The machine tool (1) according to claim 1 or 2, characterized in that, The pressure chamber (12) is located in the inner ring (4) or the outer ring (5), and during operation, the working medium is supplied to the pressure chamber (12) via the pressure line (17) to affect the pressure.

4. The machine tool (1) according to claim 1 or 2, characterized in that, An insertion disc (13), an annular piston (14), or a raised section on the outer ring (5), the inner ring (4), or the shaft disc (6) are provided to apply pressure to the raceway (10) of the axial-radial bearing (2).

5. The machine tool (1) according to any one of claims 1 to 4, characterized in that, The pressure chamber (12) is sealed using one or more seals (15).

6. The machine tool (1) according to any one of claims 3 to 5, characterized in that, The direction of movement of the annular piston (14), the insertion disc (13), or the raised section (27) is predetermined along the direction of the raceway (10).

7. The machine tool (1) according to any one of claims 3 to 6, characterized in that, The raised section (27) of the inner ring (4) is designed as a diaphragm.

8. The machine tool (1) according to any one of the preceding claims, characterized in that, The pressure chamber (12) is sealed by a material connection between the ring / pressure element (23) used to seal the pressure chamber (12) and the inner ring (4).

9. The machine tool (1) according to any one of claims 1 to 8, characterized in that, The positions of the pressure plate (13), the annular piston (14), the insertion plate, or the raised material wall (27) can be reversibly changed by the inflow of the working medium.

10. The machine tool (1) according to any one of claims 1 to 9, characterized in that, It can selectively control the inflow of the working medium to generate the predetermined prestress.

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