A hydrostatic spindle and machine tool

Abstract

This invention discloses a hydrostatic spindle and machine tool, comprising a body and a spindle core. The spindle core has a thrust disc, and the body is equipped with thrust bearings. axial spacing is formed between the thrust bearings, and the thrust disc is positioned within these axial spacings. Each thrust bearing has a thrust surface that mates with the thrust disc. Multiple circumferentially distributed first thrust oil chambers are provided on the thrust surface. Each first thrust oil chamber has a first oil inlet and a first oil return. The distance from the first oil inlet to the center of the thrust disc is less than the distance from the first oil return to the center of the thrust disc. The first thrust oil chamber is recessed from the thrust surface to the back side of the thrust bearing, and the recess depth decreases from the first oil inlet to the first oil return. This invention ensures that the spindle core can obtain sufficiently large thrust pressure under high-speed operation, reduces the risk of axial movement of the spindle core, and ultimately increases spindle rigidity, machining efficiency, and stability, improving the overall performance of the spindle under heavy loads.

Description

Technical Field

[0001] This invention relates to the field of spindles, and in particular to a hydrostatic spindle and machine tool. Background Technology

[0002] The spindle is a core functional component of modern machine tools. As modern industry demands increasing precision and stability in machine tool processing, the performance requirements for spindles are also rising. Hydrostatic spindles, due to their high rotational accuracy and compact structure, are widely used in precision and ultra-precision machining. Because of the incompressibility of liquids, hydrostatic spindles possess high rigidity, which is a crucial indicator of spindle performance. Therefore, the design trend for hydrostatic spindles is to rationally design the oil supply method and throttling structure to achieve both high rigidity and stability. However, reducing oil consumption and minimizing the risks of oil leakage, internal pressure oil flow, pressure loss, and even seal failure while ensuring sufficient rigidity and stability remains a significant challenge in the design of hydrostatic spindles. Summary of the Invention

[0003] The purpose of this invention is to at least solve one of the technical problems existing in the prior art, and to provide a hydrostatic spindle and machine tool.

[0004] The technical solution adopted by this invention to solve its technical problem is:

[0005] In a first aspect, a hydrostatic spindle includes a body and a spindle core, the spindle core being rotatably mounted on the body, the spindle core having a thrust disc, a thrust bearing being provided on the body, the thrust bearing including a first thrust bearing and a second thrust bearing, an axial gap being formed between the first thrust bearing and the second thrust bearing, the thrust disc being disposed in the axial gap, the thrust bearing having a thrust surface that mates with the thrust disc, the thrust surface having a plurality of first thrust oil chambers distributed circumferentially, each first thrust oil chamber having a first oil inlet and a first oil return hole, the distance from the first oil inlet to the center of the thrust disc being less than the distance from the first oil return hole to the center of the thrust disc, the first thrust oil chamber being recessed from the thrust surface to the back side of the thrust bearing, the recess depth of the first thrust oil chamber decreasing from the first oil inlet to the first oil return hole.

[0006] In conjunction with the first aspect, in some implementations of the first aspect, the first oil inlet holes of the plurality of first thrust oil chambers are located on a circle with the center of the thrust disc as the center and the radius as r, and the first oil return holes of the plurality of first thrust oil chambers are located on a circle with the center of the thrust disc as the center and the radius as R, where R > r.

[0007] In combination with the first aspect and the above-described implementations, in some implementations of the first aspect, the first oil return hole is located behind the first oil inlet hole along the rotation direction of the shaft core, the first thrust oil cavity has a first edge, the first edge is an arc extending from the first oil inlet hole to the first oil return hole, the first thrust oil cavity has a second edge, the second edge is located behind the first edge, and the second edge extends from the first oil return hole to the inner circumferential surface of the thrust bearing.

[0008] In combination with the first aspect and the above-described implementations, in some implementations of the first aspect, the thrust surface is provided with a plurality of second thrust oil cavities distributed circumferentially, the second thrust oil cavity is provided with a second oil inlet hole, the second thrust oil cavity is recessed from the thrust surface to the back side of the thrust bearing, the second thrust oil cavity extends circumferentially along the thrust bearing, and an oil return groove extending to the inner circumferential surface of the thrust bearing is provided between the two ends of the second thrust oil cavity and the first thrust oil cavity.

[0009] In combination with the first aspect and the above-mentioned implementation methods, in some implementation methods of the first aspect, the thrust bearing is an annular shape extending radially from the inner circumferential surface to the outer circumferential surface. The outer circumferential surface of the thrust bearing is fitted into the inner hole of the machine body. The outer circumferential surface of the thrust bearing is provided with a first annular oil groove. The first oil inlet and the second oil inlet are both connected to the first annular oil groove. The machine body is provided with a first oil supply hole that communicates with the first annular oil groove.

[0010] In combination with the first aspect and the above-mentioned implementations, in some implementations of the first aspect, the machine body is provided with a shaft core inner hole, the shaft core is disposed in the shaft core inner hole, and the inner wall surface of the shaft core inner hole is provided with multiple sets of radial oil cavities along the circumferential direction. Each set of radial oil cavities includes a first radial oil cavity and a second radial oil cavity distributed along the rotation direction of the shaft core. The depth of the first radial oil cavity is greater than the depth of the second radial oil cavity. The machine body is provided with a third oil inlet hole communicating with the first radial oil cavity and a fourth oil inlet hole communicating with the second radial oil cavity. A circumferential gap is left between two adjacent sets of radial oil cavities along the rotation direction of the shaft core, and a hydrostatic oil film gap is formed between the machine body and the shaft core at the circumferential gap.

[0011] In combination with the first aspect and the above-described implementations, in some implementations of the first aspect, the outer peripheral surface of the machine body is provided with a second annular oil groove and a plurality of third annular oil grooves, the fourth oil inlet hole of each second radial oil cavity is connected to the second annular oil groove, the third oil inlet hole of each first radial oil cavity is connected to the corresponding third annular oil groove, and the hydrostatic spindle further includes an outer housing sleeved on the outer peripheral surface of the machine body, the outer housing is provided with a second oil supply hole communicating with the second annular oil groove and a plurality of third oil supply holes corresponding to and communicating with the third annular oil groove.

[0012] In combination with the first aspect and the above-mentioned implementation methods, in some implementation methods of the first aspect, both the second oil supply port and the third oil supply port are provided with throttles.

[0013] In conjunction with the first aspect and the above-described implementations, in some implementations of the first aspect, the throttle includes a throttle rod, which includes a conical section, a sealing section, and a threaded section. The outer casing has a throttle rod mounting hole on the outside of the second oil supply hole and the third oil supply hole. The throttle rod is installed in the throttle rod mounting hole by a nut provided on the threaded section. A sealing ring is provided between the sealing section and the outer casing. The conical section is inserted into the second oil supply hole or the third oil supply hole.

[0014] In a second aspect, a machine tool includes a hydrostatic spindle as described in any implementation of the first aspect.

[0015] One of the above technical solutions has at least one of the following advantages or beneficial effects: In operation, especially during high-speed rotation, the oil enters each of the first thrust oil chambers through the first oil inlet hole. Centrifugal force drives the high-pressure oil from the first oil inlet hole to the first return oil hole along the rotation direction. Due to the dynamic pressure effect, the pressure in the first thrust oil chamber gradually increases from deep to shallow, which increases the pressure of the high-pressure oil film on the entire thrust surface, enhances the thrust effect, ensures that the shaft can obtain a sufficiently large thrust pressure under high-speed operation, reduces the risk of axial movement of the shaft, and ultimately increases the spindle stiffness, processing efficiency and stability, and improves the overall performance of the spindle under heavy load.

[0016] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0017] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0018] Figure 1 This is a cross-sectional view of an embodiment of the hydrostatic spindle of the present invention;

[0019] Figure 2 yes Figure 1 A schematic diagram of the thrust bearing thrust surface structure of one embodiment is shown;

[0020] Figure 3 yes Figure 1 The diagram shows a schematic of the first annular oil groove structure of a thrust bearing in one embodiment.

[0021] Figure 4 yes Figure 2 Cross-sectional view at point BB;

[0022] Figure 5 yes Figure 1 A cross-sectional view of the body structure of one embodiment is shown;

[0023] Figure 6 yes Figure 1 Enlarged view of a portion of point A in the middle;

[0024] Figure 7 yes Figure 1 The diagram shows a schematic of a throttle rod structure in one embodiment. Detailed Implementation

[0025] This section will describe in detail specific embodiments of the present invention. Preferred embodiments of the present invention are shown in the accompanying drawings. The purpose of the drawings is to supplement the textual description with graphics, so that people can intuitively and vividly understand each technical feature and overall technical solution of the present invention, but they should not be construed as limiting the scope of protection of the present invention.

[0026] In this invention, when directions (up, down, left, right, front, and back) are described, it is only for the convenience of describing the technical solution of this invention, and does not indicate or imply that the technical features referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation of this invention.

[0027] In this invention, "several" means one or more, "multiple" means two or more, "greater than," "less than," "exceeding," etc., are understood to exclude the stated number; "above," "below," "within," etc., are understood to include the stated number. In the description of this invention, the terms "first" and "second" are used only to distinguish technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the order of the indicated technical features.

[0028] In this invention, unless otherwise explicitly defined, the terms "setting," "installing," and "connecting" should be interpreted broadly. For example, they can refer to a direct connection or an indirect connection through an intermediate medium; a fixed connection, a detachable connection, or an integrally formed connection; a mechanical connection, an electrical connection, or a connection capable of mutual communication; or the internal connection of two components or the interaction between two components. Those skilled in the art can reasonably determine the specific meaning of the above terms in this invention based on the specific content of the technical solution.

[0029] in, Figure 2 The arrow direction indicates the rotation direction of the shaft core during operation in this embodiment of the invention. The following is in conjunction with... Figure 2 The directions shown illustrate embodiments of the present invention.

[0030] See Figure 1, Figure 2 An embodiment of the present invention provides a hydrostatic spindle, including a body 100 and a spindle core 200. The spindle core 200 is rotatably mounted on the body 100 to form a hydrostatic spindle. The spindle core 200 has a thrust disc 201, which extends radially outward from the spindle core 200. The body 100 is provided with thrust bearings 300, which include a first thrust bearing 301 and a second thrust bearing 302. An axial gap is formed between the first thrust bearing 301 and the second thrust bearing 302. The thrust disc 201 is disposed in the axial gap. The thrust disc 201 cooperates with the thrust bearings 300 on both sides to provide axial thrust force to the spindle core 200.

[0031] See Figure 1 , Figure 2 The thrust bearing 300 has a thrust surface 303 that mates with the thrust disc 201. The thrust surface 303 has multiple circumferentially distributed first thrust oil chambers 304. These first thrust oil chambers 304 are distributed uniformly or non-uniformly on the thrust surface 303. Each first thrust oil chamber 304 has a first oil inlet 305 and a first oil return 306. Each first thrust oil chamber 304 is connected to its own independent first oil inlet 305 and first oil return 306. 6. Oil supply and return, thereby forming an axial thrust acting on the thrust disc 201 on the thrust surface 303. The distance from the first oil inlet 305 to the center of the thrust disc 201 is less than the distance from the first oil return 306 to the center of the thrust disc 201. The first thrust oil cavity 304 is recessed from the thrust surface 303 toward the back side of the thrust bearing 300, and the recess depth of the first thrust oil cavity 304 decreases from the first oil inlet 305 to the first oil return 306. For example, in some embodiments, the bottom of the first thrust oil cavity 304 is an inclined surface in the direction from the first oil inlet 305 to the first oil return 306, so that the depth of the first thrust oil cavity 304 at the position of the first oil inlet 305 is greater than the depth at the position of the first oil return 306.

[0032] Combination Figure 1 , Figure 2 In operation, especially during high-speed rotation, the oil enters each of the first thrust oil chambers 304 through the first oil inlet 305. Centrifugal force drives the high-pressure oil from the first oil inlet 305 to the first return oil hole 306 along the rotation direction. Due to the dynamic pressure effect, the high-pressure oil film covers the entire thrust surface 303 through rotation. The pressure in the first thrust oil chamber 304 gradually increases from deep to shallow, which increases the pressure of the high-pressure oil film on the entire thrust surface 303, enhances the thrust effect, and ensures that the shaft core 200 can obtain a sufficiently large thrust pressure under high-speed operation. This reduces the risk of axial movement of the shaft core 200, ultimately increasing the spindle stiffness, processing efficiency and stability, and improving the overall performance of the spindle under heavy load. Finally, the high-pressure oil flows out from the first return oil hole 306 to complete the pressure relief closed loop.

[0033] In some embodiments, see Figure 2 The first oil inlet holes 305 of the multiple first thrust oil chambers 304 are located on a circle with radius r centered on the center of the thrust disc 201, and the first oil return holes 306 of the multiple first thrust oil chambers 304 are located on a circle with radius R centered on the center of the thrust disc 201, where R > r. In other words, the first oil return holes 306 of the multiple first thrust oil chambers 304 distributed circumferentially along the thrust surface 303 are located on a circle with a larger radius, and the first oil inlet holes 305 of the multiple first thrust oil chambers 304 distributed circumferentially along the thrust surface 303 are located on a circle with a smaller radius. This allows the oil in each first thrust oil chamber 304 to enter the first thrust oil chamber 304 from the same radial position, and then, driven by centrifugal force, the high-pressure oil is thrown from the first oil inlet hole 305 along the rotational direction to the first oil return hole 306, and then discharged from the first thrust oil chamber 304 from the same radial position. During this process, due to the dynamic pressure effect, the pressure in the multiple first thrust oil chambers 304 increases uniformly from deep to shallow, which causes the high-pressure oil film pressure on the entire thrust surface 303 to increase uniformly, thereby enhancing the thrust effect.

[0034] In some embodiments, see Figure 2 Along the rotation direction of the shaft core 200, the first oil return hole 306 is located behind the first oil inlet hole 305. The first thrust oil cavity 304 has a first edge 307, which is an arc extending from the first oil inlet hole 305 to the first oil return hole 306. The first thrust oil cavity 304 has a second edge 308, which is located behind the first edge 307 and extends from the first oil return hole 306 to the inner circumferential surface of the thrust bearing 300. The first thrust oil cavity 304 is fan-shaped, which facilitates the flow of oil from the first oil inlet hole 305 to the first oil return hole 306 during rotation, ensuring that the oil fills the entire first thrust oil cavity 304. In this embodiment, high-pressure oil enters the arc-shaped first thrust oil cavity 304 from the first oil inlet hole 305, which can continuously ensure the strength of the high-pressure oil film on the thrust surface 303 and improve the stability of the thrust effect.

[0035] In some embodiments, see Figure 2The thrust surface 303 is provided with multiple circumferentially distributed second thrust oil chambers 309. Each second thrust oil chamber 309 has a second oil inlet 310. The second thrust oil chambers 309 are recessed from the thrust surface 303 toward the back side of the thrust bearing 300 and extend a certain length circumferentially along the thrust bearing 300. Oil return grooves extending to the inner circumferential surface of the thrust bearing 300 are provided between the two ends of the second thrust oil chambers 309 and the first thrust oil chambers 304. During operation, oil enters the second thrust oil chambers 309 through the second oil inlet 310. The oil in the second thrust oil chambers 309 acts on the thrust disc 201 of the shaft core 200 to provide axial thrust force to the shaft core 200. Finally, the high-pressure oil flows out from the oil return groove to complete the pressure relief closed loop. Compared to the first thrust oil chamber 304, the second thrust oil chamber 309 is mainly used to provide axial thrust force to the shaft core 200 at lower speeds. In this embodiment, the first thrust oil chamber 304 and the second thrust oil chamber 309 cooperate with each other to improve the thrust resistance and stability.

[0036] Further, see Figure 1 , Figure 2 , Figure 3 , Figure 4 The thrust bearing 300 is an annular shape extending radially from its inner circumferential surface to its outer circumferential surface. The outer circumferential surface of the thrust bearing 300 is fitted into the inner hole of the machine body 100. The outer circumferential surface of the thrust bearing 300 is provided with a first annular oil groove 311. The first oil inlet 305 and the second oil inlet 310 are both connected to the first annular oil groove 311. The machine body 100 is provided with a first oil supply hole connected to the first annular oil groove 311. The oil flowing through the first oil inlet 305 and the second oil inlet 310 is throttled through a small orifice to the first thrust oil chamber 304 and the second thrust oil chamber 309. When the shaft core 200 rotates at low speed, the second thrust oil chamber 309 ensures the thrust of the thrust surface 303. When the shaft core 200 rotates at high speed, the centrifugal force carries the high-pressure oil film to the entire first thrust oil chamber 304.

[0037] In some embodiments, see Figure 1 , Figure 5 The machine body 100 is provided with a shaft core inner hole 101, and the shaft core 200 is disposed in the shaft core inner hole 101. The inner wall surface of the shaft core inner hole 101 is provided with multiple sets of radial oil cavities along the circumferential direction. The multiple sets of radial oil cavities are used to provide radial static pressure support for the rotation of the shaft core 200 in the shaft core inner hole 101. Each set of radial oil cavities includes a first radial oil cavity 102 and a second radial oil cavity 103 distributed along the rotation direction of the shaft core 200. The depth of the first radial oil cavity 102 is greater than the depth of the second radial oil cavity 103. The machine body 100 is provided with a third oil inlet hole 104 communicating with the first radial oil cavity 102 and a fourth oil inlet hole 105 communicating with the second radial oil cavity 103. A circumferential gap 106 is left between two adjacent sets of radial oil cavities along the rotation direction of the shaft core 200. A static pressure oil film gap is formed between the machine body 100 and the shaft core 200 at the circumferential gap 106.

[0038] See Figure 1 , Figure 5 In this embodiment, high-pressure oil flows into the first radial oil chamber 102 and the second radial oil chamber 103 from the third oil inlet 104 and the fourth oil inlet 105. The first radial oil chamber 102 and the second radial oil chamber 103 are open on the side facing the spindle core 200. The oil in the first radial oil chamber 102 and the second radial oil chamber 103 is carried into the hydrostatic oil film gap by the rotation of the spindle core 200. Due to the dynamic pressure effect, the oil chamber pressure gradually increases along the rotation direction, and the oil film at the hydrostatic oil film gap reaches the maximum pressure, so that a high oil film stiffness can still be achieved under low oil inlet pressure. This reduces oil consumption and greatly increases the load resistance of the spindle core 200, while reducing the risks of internal flow turbulence and sealing difficulties caused by large oil volume. Moreover, the second radial oil chamber 103 ensures continuous oil supply and improves the stability of spindle machining. The high-pressure oil flows to the oil chamber through the return oil groove and flows out along the return oil path to complete the pressure relief.

[0039] Furthermore, in some embodiments, see [link to relevant documentation]. Figure 1 , Figure 5 The outer circumferential surface of the machine body 100 is provided with a second annular oil groove 107 and a plurality of third annular oil grooves 108. The fourth oil inlet hole 105 of each second radial oil cavity 103 is connected to the second annular oil groove 107, and the third oil inlet hole 104 of each first radial oil cavity 102 is connected to the corresponding third annular oil groove 108. The hydrostatic spindle also includes an outer housing 400 sleeved on the outer circumferential surface of the machine body 100. The outer housing 400 is provided with a second oil supply hole 401 communicating with the second annular oil groove 107 and a plurality of third oil supply holes 402 corresponding to and communicating with the third annular oil grooves 108. In this embodiment, the oil in each second radial oil cavity 103 is first introduced into the second annular oil groove 107 through the third oil supply hole 402, and after being evenly distributed in the second annular oil groove 107, it flows into the second radial oil cavity 103 through the fourth oil inlet hole 105. The first radial oil chamber 102 is relatively deep, and the oil in each first radial oil chamber 102 is supplied separately. The oil is first introduced into different third annular oil grooves 108 through the third oil supply hole 402, then introduced into the corresponding third oil inlet hole 104 through the third annular oil groove 108, and finally flows into the corresponding first radial oil chamber 102. In this embodiment, the oil supply to different first radial oil chambers 102 can be independently controlled according to the actual working conditions, which greatly increases the load resistance of the shaft core 200.

[0040] Currently, the throttling methods commonly used in hydrostatic spindles are fixed throttling and internal feedback throttling. Traditional fixed throttling is relatively simple and has low manufacturing costs, but its non-adjustable nature makes it unable to respond quickly and difficult to adapt to complex machining environments. Internal feedback throttling, on the other hand, generally has higher manufacturing costs.

[0041] In some embodiments, see Figure 1 , Figure 6Both the second oil supply port 401 and the third oil supply port 402 are equipped with throttles 500. By adjusting the throttles 500, the oil flow rate can be changed, thereby changing the high-pressure oil film pressure inside the machine body 100 to adapt to the needs of different working environments. This embodiment overcomes the shortcomings of traditional fixed throttling methods that cannot be adjusted in real time, and is also easy to manufacture and has a low cost.

[0042] In some embodiments, see Figure 1 , Figure 6 , Figure 7 The throttle 500 includes a throttle rod 501, which includes a conical section 502, a sealing section 503, and a threaded section 504. The outer housing 400 has throttle rod mounting holes on the outside of the second oil supply hole 401 and the third oil supply hole 402. The throttle rod 501 is installed in the throttle rod mounting holes through a nut 505 provided on the threaded section 504. The sealing section 503 has a groove for installing a sealing ring 506. A sealing ring 506 is provided between the sealing section 503 and the outer housing 400. The conical section 502 is inserted into the second oil supply hole 401 or the third oil supply hole 402. The conical surface and the oil supply hole form a gap for throttling. The O-ring seal in the middle seals and ensures the throttling effect. The rear end of the throttle 500 has an external thread, which is connected to the nut through the thread. The nut is then fixed to the outer housing 400 through the external thread. The insertion depth of the throttle 500 is adjusted by turning the thread at the tail of the knob, thereby changing the gap between the throttle 500 and the oil inlet channel. This embodiment overcomes the shortcomings of traditional fixed throttling methods that cannot be adjusted in real time, while also being easy to manufacture and low in cost. By adjusting the screw-in depth of the throttle 500, the throttling flow rate can be easily changed, allowing the internal high-pressure oil film pressure to be altered to adapt to complex working conditions.

[0043] Embodiments of the present invention also provide a machine tool including the hydrostatic spindle of any of the above embodiments.

[0044] In the description of this specification, references to terms such as "example," "embodiment," or "some embodiments" indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0045] Of course, the present invention is not limited to the above-described embodiments. Those skilled in the art can make equivalent modifications or substitutions without departing from the spirit of the present invention, and these equivalent modifications or substitutions are all included within the scope defined by the claims of this application.

Claims

1. A hydrostatic spindle, characterized in that, The assembly includes a body and a shaft core, the shaft core being rotatably mounted on the body. The shaft core has a thrust disc. The body is provided with a thrust bearing, the thrust bearing including a first thrust bearing and a second thrust bearing, with an axial gap between the first and second thrust bearings. The thrust disc is disposed within the axial gap. The thrust bearing has a thrust surface that mates with the thrust disc. The thrust surface has a plurality of circumferentially distributed first thrust oil chambers, each first thrust oil chamber having a first oil inlet and a first oil return hole. The distance from the first oil inlet to the center of the thrust disc is less than the distance from the first oil return hole to the center of the thrust disc. The first thrust oil chamber is recessed from the thrust surface to the back side of the thrust bearing, and extends from the first oil inlet. The depth of the first thrust oil cavity decreases in the direction towards the first return oil hole. The first oil inlet holes of the plurality of first thrust oil cavities are located on a circumference with the center of the thrust disc as the center and the radius as r. The first return oil holes of the plurality of first thrust oil cavities are located on a circumference with the center of the thrust disc as the center and the radius as R, where R > r. Along the rotation direction of the shaft core, the first return oil hole is located behind the first oil inlet hole. The first thrust oil cavity has a first edge, which is an arc extending from the first oil inlet hole to the first return oil hole. The first thrust oil cavity has a second edge, which is located behind the first edge. The second edge extends from the first return oil hole to the inner circumferential surface of the thrust bearing.

2. The hydrostatic spindle according to claim 1, characterized in that, The thrust surface is provided with a plurality of second thrust oil chambers distributed circumferentially. Each second thrust oil chamber is provided with a second oil inlet hole. The second thrust oil chamber is recessed from the thrust surface to the back side of the thrust bearing. The second thrust oil chamber extends circumferentially along the thrust bearing. The two ends of the second thrust oil chamber and the first thrust oil chamber are provided with oil return grooves extending to the inner circumferential surface of the thrust bearing.

3. The hydrostatic spindle according to claim 2, characterized in that, The thrust bearing is an annular shape extending radially from the inner circumferential surface to the outer circumferential surface. The outer circumferential surface of the thrust bearing is fitted into the inner hole of the machine body. The outer circumferential surface of the thrust bearing is provided with a first annular oil groove. The first oil inlet and the second oil inlet are both connected to the first annular oil groove. The machine body is provided with a first oil supply hole that communicates with the first annular oil groove.

4. The hydrostatic spindle according to claim 1, characterized in that, The machine body is provided with a shaft core inner hole, and the shaft core is disposed in the shaft core inner hole. The inner wall surface of the shaft core inner hole is provided with multiple sets of radial oil cavities along the circumferential direction. Each set of radial oil cavities includes a first radial oil cavity and a second radial oil cavity distributed along the rotation direction of the shaft core. The depth of the first radial oil cavity is greater than the depth of the second radial oil cavity. The machine body is provided with a third oil inlet hole communicating with the first radial oil cavity and a fourth oil inlet hole communicating with the second radial oil cavity. A circumferential gap is left between two adjacent sets of radial oil cavities along the rotation direction of the shaft core. A hydrostatic oil film gap is formed between the machine body and the shaft core at the circumferential gap.

5. The hydrostatic spindle according to claim 4, characterized in that, The outer circumferential surface of the machine body is provided with a second annular oil groove and a plurality of third annular oil grooves. The fourth oil inlet hole of each second radial oil cavity is connected to the second annular oil groove, and the third oil inlet hole of each first radial oil cavity is connected to the corresponding third annular oil groove. The hydrostatic spindle also includes an outer housing sleeved on the outer circumferential surface of the machine body. The outer housing is provided with a second oil supply hole connected to the second annular oil groove and a plurality of third oil supply holes corresponding to and connected to the third annular oil groove.

6. The hydrostatic spindle according to claim 5, characterized in that, Both the second oil supply port and the third oil supply port are equipped with throttles.

7. The hydrostatic spindle according to claim 6, characterized in that, The throttle includes a throttle rod, which includes a conical section, a sealing section, and a threaded section. The outer casing has a throttle rod mounting hole on the outside of the second oil supply hole and the third oil supply hole. The throttle rod is installed in the throttle rod mounting hole by a nut provided on the threaded section. A sealing ring is provided between the sealing section and the outer casing. The conical section is inserted into the second oil supply hole or the third oil supply hole.

8. A machine tool, characterized in that, The hydrostatic spindle includes any one of claims 1 to 7.

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