Internal feedback hydrostatic bearing and hydrostatic spindle structure

Abstract

An internal feedback hydrostatic bearing and a hydrostatic spindle structure relate to the field of bearing design. The problems that according to an existing hydrostatic bearing, hydraulic oil in an oil inlet cavity and an oil collecting cavity still easily enters a bearing oil cavity on the side, and consequently the rotating precision of a main shaft borne by the hydrostatic bearing is insufficient and unstable are solved. N pairs of throttlers are arranged, and the two throttlers in each pair are arranged on the two sides of the radial direction and / or the two sides of the axial direction of the main shaft correspondingly; each throttler comprises an oil inlet groove, an oil collecting groove and a bearing oil groove, the oil collecting groove surrounds the oil inlet groove, two opposite groove edges of the oil inlet groove are oil sealing edges, the other two opposite groove edges of the oil inlet groove are throttling edges, the throttling edges are configured to be gap throttling openings, and pressure oil in the oil inlet groove can be pressed into the oil collecting groove from the gap throttling openings; the peripheral groove edges of the oil collecting groove and the bearing oil groove are oil sealing edges, the oil collecting groove is communicated with the bearing oil groove of the other throttler, and pressure oil in the oil collecting groove is pressed into the bearing oil groove of the other throttler to achieve internal feedback.

Description

Technical Field

[0001] The present invention relates to the field of bearing design, and in particular to an internal feedback hydrostatic bearing and a hydrostatic spindle structure. Background Art

[0002] In recent years, cutting-edge fields such as aerospace, precision instruments, and chip manufacturing have seen increasing demands for machining accuracy and performance, directly driving the rapid development of ultra-precision machining technology and equipment. In line with this development trend, hydrostatic bearings, as key components of precision and ultra-precision machine tool spindles, have become an indispensable support element for the functional components of ultra-precision machining tools due to their superior characteristics. They have been widely used in core components such as hydrostatic spindles and hydrostatic turntables. Hydrostatic bearings can provide continuous and stable support for equipment under demanding conditions, such as withstanding high loads, maintaining high precision, and achieving high speeds, highlighting their irreplaceable core advantages in the field of ultra-precision machining.

[0003] Internal feedback hydrostatic bearings feature a relatively simple structure, fast response, and high load-bearing rigidity, making them widely used in ultra-precision machine tools, semiconductor manufacturing equipment, aerospace measurement instruments, industrial robots, and other fields. However, when the spindle is subjected to external loads, hydraulic oil from the oil inlet and oil collection chambers of the internal feedback hydrostatic bearing can easily flow into the load-bearing oil chamber on the bearing side. This results in insufficient spindle rotational accuracy and unstable performance. Summary of the Invention

[0004] In view of this, the present invention provides an internal feedback hydrostatic bearing and a hydrostatic spindle structure, which can achieve strict gap throttling and two-way internal feedback, thereby improving the overall rotation accuracy and performance stability of the hydrostatic bearing, thereby improving the spindle stiffness, and ensuring that the spindle is always suspended in the high-pressure oil film and rotates stably in the high-pressure oil film.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0006] An internal feedback hydrostatic bearing is provided with N pairs of throttles, and the two throttles in each pair are respectively arranged on both sides of the radial direction and / or both sides of the axial direction of the main shaft for radial positioning and / or axial positioning of the main shaft; each throttle includes an oil inlet groove, an oil collecting groove and a bearing oil groove, the oil collecting groove is surrounded by the oil inlet groove, two opposite groove edges of the oil inlet groove are oil sealing edges, and the other two opposite groove edges are throttling edges, which are configured as gap throttling ports, and the pressure oil in the oil inlet groove can be pressed into the oil collecting groove from the gap throttling ports, and the groove edges around the oil collecting groove and the bearing oil groove are all oil sealing edges, and the oil collecting groove is connected to the bearing oil groove of the other throttle in the pair, and the pressure oil in the oil collecting groove is pressed into the bearing oil groove of the other throttle to achieve internal feedback.

[0007] Further, the oil inlet groove is a long strip-shaped groove, and the groove edges at the two ends of the length direction of the oil inlet groove are oil sealing edges, and the groove edges at the two ends of the width direction of the oil inlet groove are throttle edges.

[0008] Further, the width of the oil sealing edge is greater than the width of the throttle edge.

[0009] Further, the throttle further comprises an oil discharge groove, and the pressure oil in the bearing oil groove can be discharged into the oil discharge groove.

[0010] Further, the throttle is a radial throttle for radial positioning of the main shaft, and a pair of two radial throtles are arranged on the inner ring wall of the static pressure bearing and are located on the two sides of the central axis of the main shaft, and the bearing oil groove of the radial throttle is surrounded by the oil collecting groove and extends along the direction of the shaft of the static pressure bearing.

[0011] Further, the throttle is an axial throttle for axial positioning of the main shaft, and a pair of two axial throtles are arranged on the two end faces of the axial direction of the static pressure bearing, and the bearing oil groove of the axial throttle is arranged between the two adjacent oil collecting grooves.

[0012] Further, the bearing oil groove of the axial throttle is an arc-shaped groove and extends along the circumferential direction of the static pressure bearing.

[0013] Further, the four gap throttle ports in each pair of throtles and the two bearing oil grooves form a full-bridge liquid resistance network.

[0014] A static pressure main shaft structure comprises a support shell, a main shaft, a bearing sleeve, a thrust sleeve, a thrust ring, a locking nut and an inner feedback static pressure bearing; one end of the main shaft is provided with a shaft shoulder, the static pressure bearing is provided with two, the two static pressure bearings are oppositely sleeved on the front and rear ends of the main shaft, the thrust sleeve is sleeved on the main shaft and is located between the two static pressure bearings, the thrust sleeve presses the static pressure bearing at the front end on the shaft shoulder of the main shaft, the thrust ring is sleeved on the main shaft and presses the static pressure bearing at the rear end on the thrust sleeve, and the thrust ring is locked by the locking nut; each static pressure bearing is provided with a bearing sleeve, and the bearing sleeve is assembled into the support shell.

[0015] Further, the throttle of the static pressure bearing comprises a radial throttle and an axial throttle, two total oil inlets are arranged on the inner wall of the support shell, and two total oil inlets are arranged on the support shell and correspond to the two total oil inlets; two annular oil inlets are arranged on the inner ring wall of the bearing sleeve, two sleeve oil inlet holes are arranged on the bearing sleeve and correspond to the two annular oil inlets, and the two sleeve oil inlet holes correspond to one of the total oil inlets of the support shell; the two annular oil inlets supply oil to the radial throttle and the axial throttle of the static pressure bearing.

[0016] Compared with the prior art, the present application has the following beneficial effects:

[0017] 1. In addition to the throttling edge, the oil inlet groove of the throttle of the hydrostatic bearing of the present invention is also designed with an oil sealing edge. In this way, the throttling edge can be kept away from the four corners of the oil groove, and the pressure oil is only pressed out from the slit throttling port formed by the throttling edge, thereby avoiding the pressure oil from throttling from the four corners of the oil groove with uneven thickness, thereby achieving strict gap throttling, making the throttling effect of the throttle more consistent with the linear characteristics of the gap throttling, and facilitating the calculation of the oil inlet amount and oil pressure of the pressure oil of the throttle.

[0018] 2. The design of the oil sealing edge and oil collecting groove of the radial throttle of the present invention is equivalent to setting up two barriers between the oil inlet groove and the bearing oil groove. Compared with designing the oil inlet position of the throttle as a throttle platform, these two barriers can prevent the pressure oil in the oil inlet groove from directly leaking into the bearing oil groove on the corresponding side. The oil collecting groove and the bearing oil groove of the axial throttle of the present invention are set separately, which can also prevent the pressure oil in the oil inlet groove and the oil collecting groove from being pressed into the bearing oil groove on the corresponding side. That is, the pressure oil in both the radial throttle and the axial throttle can be completely pressed into the bearing oil groove on the opposite side. The pressure oil in the bearing oil groove can maintain stable oil pressure due to the action of the surrounding oil sealing edges, thereby ensuring that the main shaft can rotate stably under radial load and / or axial load.

[0019] 3. In addition to the radial throttle, the hydrostatic bearing of the present invention is also designed with an axial throttle. When the main shaft is subjected to radial load and / or axial load, these two throttles can play an internal feedback role in the radial and axial directions, further improving the overall rotation accuracy and performance stability of the hydrostatic bearing, increasing the main shaft stiffness, and ensuring that the main shaft is always suspended in the high-pressure oil film and rotates stably in the high-pressure oil film.

[0020] 4. The present invention equates the four slit throttle ports in each pair of throttles of the hydrostatic bearing to four controllable hydraulic resistors R1, R2, R3, and R4. Pin is the input oil pressure of the main oil channel, and P1 and P2 are the oil pressures of the two symmetrically distributed load-bearing oil chambers in each pair of throttles in the hydrostatic bearing. The hydraulic resistance network structure they form is similar to a full-bridge electric bridge. Through this full-bridge hydraulic resistance network, a quantitative relationship between the hydraulic parameters of the hydrostatic bearing and the load response can be established, the oil pressure in each load-bearing oil chamber can be quickly calculated, and the influence of each hydraulic parameter on the bearing response can be systematically analyzed to reflect its inherent laws. Compared with traditional formula calculations, the combination of the full-bridge hydraulic resistance network model can make the parameter relationship of the hydrostatic bearing clearer, making it easier to carry out systematic research on hydrostatic bearings. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The accompanying drawings are incorporated in and constitute a part of this application and are used to provide a further understanding of the present invention.

[0022] Figure 1 Schematic diagram of the three-dimensional structure of an internal feedback hydrostatic bearing of the present invention Figure 1.

[0023] Figure 2 Schematic diagram of the three-dimensional structure of an internal feedback hydrostatic bearing of the present invention Figure 2 .

[0024] Figure 3 A cross-sectional view of an internal feedback hydrostatic bearing of the present invention Figure 1 .

[0025] Figure 4 A cross-sectional view of an internal feedback hydrostatic bearing of the present invention Figure 2 .

[0026] Figure 5 A cross-sectional view of an internal feedback hydrostatic bearing of the present invention Figure 3 .

[0027] Figure 6 A cross-sectional view of an internal feedback hydrostatic bearing of the present invention Figure 4 .

[0028] Figure 7 This is a schematic diagram of the hydraulic oil circuit of an internal feedback hydrostatic bearing of the present invention.

[0029] Figure 8 Schematic diagram of a full-bridge hydraulic resistance network of an internal feedback hydrostatic bearing of the present invention.

[0030] Figure 9 It is a schematic diagram of a static pressure spindle structure of the present invention.

[0031] Figure 10 It is a cross-sectional schematic diagram of a static pressure spindle structure of the present invention.

[0032] Figure 11 Exploded view of the supporting shell.

[0033] Figure 12 Schematic diagram of the structure of the bearing sleeve.

[0034] Figure 13 Schematic diagram of the cross section of the bearing sleeve.

[0035] Figure 14 This is an exploded cross-sectional view of a static pressure spindle structure of the present invention.

[0036] Description of reference numerals:

[0037] 1-Radial throttle; 11-Radial oil inlet groove; 111-First oil sealing edge; 112-First throttling edge; 12-Radial oil collecting groove; 121-Second oil sealing edge; 13-Radial load-bearing oil groove; 131-Third oil sealing edge; 2-First main oil channel; 3-Radial throttling channel; 31-Oil drain channel; 32-Annular oil groove; 33-Oil inlet channel; 4-Axial throttle; 41-Axial oil inlet groove; 411-Third throttling edge; 412-Fourth oil sealing edge; 42-Axial oil collecting groove Groove; 421-fifth oil sealing edge; 43-axial load-bearing oil groove; 431-sixth oil sealing edge; 44-axial oil drain groove; 45-second main oil channel; 46-axial throttling channel; 5-support housing; 51-front end cover; 52-support sleeve; 521-total oil inlet; 522-total oil inlet groove; 53-rear end cover; 6-main shaft; 61-shaft shoulder; 7-bearing sleeve; 71-sleeve oil inlet hole; 72-annular oil inlet groove; 8-thrust sleeve; 9-thrust ring; 10-locking nut. DETAILED DESCRIPTION

[0038] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0039] Figure 1 and Figure 2 FIG1 shows a schematic structural diagram of an internal feedback hydrostatic bearing according to the present embodiment. Figure 1 and Figure 2 In this embodiment, an internal feedback hydrostatic bearing is provided with N pairs of throttles and multiple flow channels, wherein the N pairs of throttles include a radial throttle arranged on the inner wall of the hydrostatic bearing and an axial throttle arranged on the end face of the hydrostatic bearing, the radial throttle is used for radial positioning of the main shaft, and the axial throttle is used for axial positioning of the main shaft; the multiple flow channels supply oil to the radial throttle and the axial throttle respectively, and the two throttles in each pair are connected through the flow channel to form internal feedback, thereby ensuring the stability of the operation of the main shaft.

[0040] Combine Figure 3 and Figure 4 The internal feedback hydrostatic bearing of this embodiment is equipped with two pairs of radial throttles 1 for radial positioning of the main shaft 6, four first main oil passages 2, and four radial throttling channels 3. The two radial throttles 1 in each pair are symmetrically arranged on either side of the hydrostatic bearing's central axis, and the four radial throttles 1 are evenly distributed circumferentially on the inner wall of the hydrostatic bearing. The first main oil passages 2 serve as the oil inlet channels for the radial throttles 1. Each first main oil passage 2 connects to a radial throttle 1 to supply oil to that radial throttle 1. Each pair of radial throttles 1 corresponds to two radial throttling channels 3, and the two radial throttling channels 3 are connected.

[0041] Combine Figure 10 After the static pressure bearing is assembled with the main shaft 6, the four radial throttles 1 are evenly arranged around the main shaft 6. Figure 3 and Figure 6 , each radial throttle 1 includes a radial oil inlet groove 11, a radial oil collecting groove 12, a radial load-bearing oil groove 13 and a radial oil drain groove 14 arranged in sequence from the inside to the outside. The radial oil inlet groove 11, the radial oil collecting groove 12, the radial load-bearing oil groove 13 and the radial oil drain groove 14 and the axial surface of the main shaft 6 form a radial oil inlet chamber, a radial oil collecting chamber, a radial load-bearing oil chamber and a radial oil drain chamber respectively. The first main oil channel 2 runs through the outer ring surface of the hydrostatic bearing and the radial oil inlet groove 11 to supply oil to the radial oil inlet chamber. The radial oil collecting groove 12 of each radial throttle 1 is connected to the radial load-bearing oil groove 13 of the radial throttle 1 on the opposite side via a radial throttling channel 3, so that the radial oil collecting chambers on both sides are connected to the radial load-bearing oil chamber. Combined Figure 6 The radial oil inlet groove 11 is a long, rectangular groove. The groove edges at both ends of the radial oil inlet groove 11 in the longitudinal direction are first oil-sealing edges 111. The groove edges at both ends of the radial oil inlet groove 11 in the width direction are first throttling edges 112. These first throttling edges 112 form a first slit throttling opening with the axial surface of the main shaft 6. The width of the first throttling edge 112 is smaller than that of the first oil-sealing edge 111. The preferred width of the first throttling edge 112 is 2 mm, while the preferred width of the first oil-sealing edge is 8-10 mm. Since slit throttling can only occur in the first throttling edge 112, which has a very small thickness, the first oil-sealing edge 111 is too wide to produce slit throttling. This means that the pressurized oil in the radial oil inlet groove 11 cannot flow out of the gap between the first oil-sealing edge 111 and the main shaft 6. Even if it does flow out, only a small amount of pressurized oil may leak. Therefore, the pressurized oil in the radial oil inlet chamber of this embodiment can only be pressed into the radial oil collecting chamber through the first slit throttling opening, strictly achieving slit throttling. Combine Figure 5 and Figure 6 The radial oil collecting groove 12 is a rectangular groove, and the groove edges around the radial oil collecting groove 12 are all second oil sealing edges 121 of equal width. Similarly, the second oil sealing edge 121 can prevent the pressure oil from leaking into the radial load-bearing oil cavity on this side, ensuring that the pressure oil in the radial oil collecting cavity can be fully pressed into the paired radial load-bearing oil cavity on the opposite side. Figure 3 and Figure 4 The radial load-bearing oil groove 13 is a rectangular groove extending along the axis of the hydrostatic bearing. Its four edges are surrounded by a third oil-sealing edge 131, which prevents leakage of pressurized oil. This third oil-sealing edge 131 seals the pressurized oil within the load-bearing oil chamber, providing stable pressure on the main shaft. Radial drain grooves 14 are located at both ends of the radial load-bearing oil groove 13 in the width direction to collect any small amounts of pressurized oil that leaks from the radial load-bearing oil groove 13.

[0042] Combine Figure 4The radial throttle channel 3 of the embodiment comprises an oil discharge channel 31, an annular oil groove 32 and an oil inlet channel 33 in sequence, wherein the annular oil groove 32 is a long strip-shaped groove opened on the outer ring surface of the hydrostatic bearing along the circumferential direction of the hydrostatic bearing, the oil discharge channel 31 is a deep hole penetrating the radial oil collecting groove 12 and the annular oil groove 32 along the radial direction of the hydrostatic bearing, and the oil inlet channel 33 is a deep hole penetrating the radial bearing oil groove 13 and the annular oil groove 32 along the radial direction of the hydrostatic bearing, wherein the oil discharge channel 31 and the oil inlet channel 33 are respectively located at the two end portions of the annular oil groove 32.

[0043] When the main shaft 6 is in a zero load state in the radial direction, the central axis of the main shaft 6 coincides with the central axis of the hydrostatic bearing (not considering the weight of the main shaft 6), and the pressure oil can be introduced into the four radial throttles 1 simultaneously via the four first main oil channels 2, and the flow of the pressure oil is the same. The pressure oil in the same radial throttle 1 is pressed into the corresponding radial oil inlet cavity by the first main oil channel 2, and then is pressed into the radial oil collecting cavity from the first gap throttle of the radial oil inlet cavity and the radial oil collecting cavity, and the pressure oil in the radial oil collecting cavity flows into the oil discharge channel 31, the annular oil groove 32 and the oil inlet channel 33 in sequence, and then is pressed into the radial bearing oil cavity in the opposite radial throttle 1, at this time, the four radial bearing oil cavities around the main shaft 6 are filled with equal amounts of pressure oil, a bearing oil film with a fixed thickness is formed between the main shaft 6 and the hydrostatic bearing, and the stable rotation of the main shaft 6 is ensured.

[0044] When the main shaft 6 is in a load state in the radial direction, the central axis of the main shaft 6 no longer coincides with the central axis of the hydrostatic bearing, and the main shaft 6 deviates to one of the radial throttles 1 in each pair of radial throttles 1, at this time, the gap between the radial bearing oil groove of the radial throttle 1 (hereinafter referred to as the radial throttle on the same side) and the main shaft 6 is reduced, and the gap between the radial bearing oil groove of the other radial throttle 1 (hereinafter referred to as the radial throttle on the opposite side) and the main shaft 6 is increased, the pressure of the radial bearing oil cavity of the radial throttle on the opposite side is reduced, and the first throttle edge arranged on the same side for controlling the radial bearing oil cavity on the opposite side is changed due to the smaller gap, the pressure loss caused by the gap throttling is increased, so that the pressure entering the radial bearing oil cavity on the opposite side becomes smaller; the pressure of the radial bearing oil cavity on the same side is increased due to the smaller gap, and the first throttle edge arranged on the opposite side for controlling the radial bearing oil cavity on the same side is changed due to the larger gap, the pressure loss caused by the gap throttling is reduced, so that the pressure entering the radial bearing oil cavity on the same side becomes larger. The larger pressure of the radial bearing oil cavity on the same side can resist the load of the main shaft 6, restore the gap change between the hydrostatic bearing and the main shaft 6, and play a role of internal feedback in the radial direction. The stiffness of the main shaft 6 is improved, and the main shaft 6 is always suspended in the high-pressure oil film and rotates stably in the high-pressure oil film.

[0045] In addition to being designed with a throttling edge, the groove edge of the radial oil inlet groove 11 of this embodiment is also designed with an oil sealing edge. The width of the throttling edge is smaller than that of the oil sealing edge, so that the throttling edge can be kept away from the four corners of the oil groove, and the pressure oil is only pressed out from the slit throttling port formed by the throttling edge, thereby avoiding the pressure oil from being throttled from the four corners of the oil groove with uneven thickness. Compared with designing the oil inlet position of the throttle as a throttling platform (the middle position of the oil collecting tank is a platform with an oil inlet hole on the platform, which is the throttling platform), the gap throttling is strictly realized, so that the throttling effect of the throttle is more in line with the linear characteristics of the gap throttling, which is beneficial to the calculation of the oil inlet amount and oil pressure of the pressure oil of the throttle. Furthermore, the design of the first oil sealing edge 111 of the radial oil inlet groove 11 and the radial oil collecting groove 12 is equivalent to providing two barriers between the radial oil inlet groove 11 and the radial load-bearing oil groove 13. Compared to a throttle plate, these two barriers prevent the pressurized oil in the radial oil inlet groove 11 from leaking directly into the radial load-bearing oil groove 13 on the corresponding side. At the same time, the pressurized oil in the radial oil collecting cavity is prevented from being pressed into the radial load-bearing oil cavity on the corresponding side by the four oil sealing edges. In other words, it can be completely pressed into the radial load-bearing oil cavity on the opposite side, achieving internal feedback in the radial direction of the hydrostatic bearing and ensuring stable rotation of the main shaft 6 under load.

[0046] like Figure 1 、 Figure 2 、 Figure 5 and Figure 6 As shown, the internal feedback hydrostatic bearing of this embodiment is also provided with two pairs of axial throttles 4 for axial positioning of the main shaft 6, four second main oil passages 45 and four axial throttle channels 46. The two axial throttles 4 in each pair are respectively provided at the axial end faces of the hydrostatic bearing. This is equivalent to a total of four axial throttles 4, with two axial throttles 4 provided at each end face of the hydrostatic bearing. Figure 1 and Figure 2 It can be seen that the two axial throttles 4 at the same end face of the hydrostatic bearing are centrally symmetrically arranged.

[0047] Combine Figure 1 and Figure 2 , each axial throttle 4 includes an axial oil inlet groove 41, an axial oil collecting groove 42, an axial load-bearing oil groove 43 and an axial oil drain groove 44. The axial oil inlet groove 41 is a long strip groove, the axial oil collecting groove 42 is a rectangular groove, the axial oil collecting groove 42 is surrounded by the axial oil inlet groove 41, and the axial load-bearing oil groove 43 is arranged between the two axial oil collecting grooves 42. The axial load-bearing oil groove 43 is an arc-shaped groove and extends along the circumferential direction of the hydrostatic bearing. Since the end face area of ​​the hydrostatic bearing is relatively small, the axial load-bearing oil groove 43 is set separately from the axial oil inlet groove 41 and the axial oil collecting groove 42, which can increase the area of ​​the axial load-bearing oil groove 43 and improve the bearing capacity of the bearing oil film. Combined with Figure 1The axial oil drain groove 44 is a groove formed by the groove edge of the axial oil collecting groove 42 and the groove edge of the axial bearing oil groove 43. Figure 5 and Figure 7 The second main oil passage 45 is the oil inlet passage of the axial throttle 4. The second main oil passage 45 is L-shaped. One end of the second main oil passage 45 is located on the outer ring surface of the static pressure bearing, and the other end is connected to the axial oil inlet groove 41. Figure 6 Each pair of axial throttles 4 corresponds to two axial throttle channels 46. The axial oil collecting groove 42 of each axial throttle 4 is arranged in front and back relation with the axial bearing oil groove 43 of the other axial throttle 4 in the pair, and is connected by an axial throttle channel 46. Axial throttle channel 46 is a straight channel opened along the axis of the hydrostatic bearing. This not only simplifies the complexity of the flow channel and the processing technology, but also reduces pressure loss. At the same time, throttling feedback can be achieved between the two paired axial throttles 4, which ensures stable rotation of the main shaft 6.

[0048] Combine Figure 10 After the hydrostatic bearing and the main shaft 6 are assembled into a hydrostatic main shaft structure, the axial oil inlet groove 41, the axial oil collecting groove 42, the axial load-bearing oil groove 43 and the axial oil drain groove 44 can form an axial oil inlet cavity, an axial oil collecting cavity, an axial load-bearing oil cavity and an axial oil drain cavity between the shaft shoulder of the main shaft 6, the thrust ring 9 or the end face of the thrust sleeve 8. Figure 1 The groove edges at both ends of the axial oil inlet groove 41 in the length direction are fourth oil sealing edges 412, and a fourth oil sealing gap is formed between the fourth oil sealing edge 412 and the shaft shoulder of the main shaft 6, the thrust ring 9 or the end face of the thrust sleeve 8; the groove edges at both ends of the axial oil inlet groove 41 in the width direction are third throttling edges 411, and a third gap throttling opening is formed between the third throttling edge 411 and the shaft shoulder of the main shaft 6, the thrust ring 9 or the end face of the thrust sleeve 8. The width of the third throttling edge 411 is smaller than that of the fourth oil sealing edge. The width of 412, the preferred width of the third throttling edge 411 is 2mm, and the preferred width of the fourth oil sealing edge 412 is 8~10mm; similarly, since gap throttling can only occur in the third throttling edge 411 with a very small thickness, the fourth oil sealing edge 412 cannot produce gap throttling due to its excessive width, that is, the pressure oil in the axial oil inlet groove 41 cannot flow out from the gap between the third throttling edge 411 and the main shaft 6. Even if it flows out, only a small amount of pressure oil may leak. Therefore, the pressure oil in the axial oil inlet chamber of this embodiment can only be pressed into the axial oil collecting chamber from the third gap throttling port, strictly realizing gap throttling. Combined with Figure 1 、 Figure 2 and Figure 3 The groove edges around the axial load-bearing oil groove 43 are the sixth oil sealing edges 431, which can prevent the pressure oil from leaking.

[0049] When the main shaft 6 is in a zero-load state in the axial direction, pressurized oil can be simultaneously introduced into the four axial restrictors 4 via the four second main oil passages 45, with the same flow rate. The pressurized oil in the same axial restrictor 4 is forced into the corresponding axial oil inlet chamber via the second main oil passage 45. Then, it is forced into the axial oil collecting chamber through the third slit throttling port between the axial oil inlet chamber and the axial oil collecting chamber. The pressurized oil in the axial oil collecting chamber is then forced into the opposite axial load-bearing oil chamber in the opposite axial restrictor 4 via the axial throttling passage 46. At this point, both axial ends of the main shaft 6 are filled with equal amounts of pressurized oil, forming a load-bearing oil film of constant thickness at each end, ensuring stable rotation of the main shaft 6.

[0050] When the main shaft 6 is under load in the axial direction, the main shaft 6 moves toward one end in the axial direction, so that the space where the axial load-bearing oil grooves of the two axial throttles 4 at one end of the hydrostatic bearing (hereinafter referred to as the axial throttles on this side) are located becomes smaller, and the space where the axial load-bearing oil grooves of the two axial throttles 4 at the other end (hereinafter referred to as the axial throttles on the opposite side) are located becomes larger, and the pressure in the axial load-bearing oil chamber of the opposite side axial throttle will decrease. At the same time, the third throttle edge arranged on this side for controlling the axial load-bearing oil chamber on the opposite side will increase due to the smaller gap, and the pressure loss caused by the gap throttling will become larger, so that the pressure entering the axial load-bearing oil chamber on the opposite side will become smaller; the axial load-bearing oil chamber on this side will increase due to the smaller gap, and at the same time, the third throttle edge arranged on the opposite side for controlling the axial load-bearing oil chamber on this side will decrease due to the larger gap, and the pressure loss caused by the gap throttling will become smaller, so that the pressure entering the axial load-bearing oil chamber on this side will become larger. The higher pressure in the axial load-bearing oil chamber on this side can resist the axial load on the main shaft 6, restore the gap change between the hydrostatic bearing and the main shaft 6, and provide internal feedback in the axial direction. This improves the rigidity of the main shaft 6 and ensures that the main shaft 6 is always suspended in the high-pressure oil film and rotates stably within it.

[0051] As can be seen, the third throttling edge 411 of the axial oil inlet groove 41 in the axial throttle 4 of this embodiment is located at a longer position within the axial oil inlet groove 41. Therefore, the length of the third throttling edge 411 is longer than the length of the fourth oil sealing edge 412. This allows the third throttling edge 411 to be kept away from the four corners of the axial oil inlet groove 41, preventing the pressurized oil from being throttled at the four corners of the axial oil inlet groove 41, where the thickness is uneven. This achieves strict gap throttling, making the throttling effect of the throttle more consistent with the linear characteristics of gap throttling, and facilitating the calculation of the pressurized oil inlet volume and oil pressure of the axial throttle 4. Furthermore, the axial oil collecting groove 42 is separately disposed from the axial bearing oil groove 43, and the groove edges surrounding the axial oil collecting groove 42 serve as oil sealing edges. Therefore, the pressurized oil in the axial oil collecting groove 42 will not leak into the axial bearing oil groove 43, but will be completely compressed into the opposite axial bearing oil chamber, achieving strict internal feedback and ensuring stable rotation of the main shaft 6 under axial load.

[0052] Figure 8 The full-bridge hydraulic resistance network of the hydrostatic bearing of this embodiment shows the hydraulic resistance network system composed of the hydrostatic bearing. Based on the equivalent hydraulic full-bridge theory, each gap throttle port in the above analysis process can be regarded as a hydraulic resistance with controllable resistance. That is, the four gap throttle ports in each pair of throttles of the hydrostatic bearing of this embodiment are equivalent to four hydraulic resistances R1, R2, R3 and R4 with controllable resistance. Pin is the input oil pressure of the main oil channel, and P1 and P2 are the oil pressures of the two symmetrically distributed load-bearing oil chambers in each pair of throttles in the hydrostatic bearing. The hydraulic resistance network structure composed of them is similar to the full-bridge electric bridge. Through the full-bridge hydraulic resistance network, the quantitative relationship between the hydraulic parameters of the hydrostatic bearing and the load response can be established, the oil pressure in each load-bearing oil chamber can be quickly calculated, the influence of each hydraulic parameter on the bearing response can be systematically analyzed, and its internal laws can be reflected. Compared with the traditional formula calculation, the combination of the full-bridge hydraulic resistance network model can make the parameter relationship of the hydrostatic bearing clearer, which is convenient for carrying out systematic research on hydrostatic bearings.

[0053] Example 2:

[0054] Figure 9 and Figure 10 A schematic diagram of a static pressure spindle structure of this embodiment is shown, combined with Figure 9 and Figure 10 ,

[0055] The hydrostatic spindle structure of this embodiment includes a support housing 5, a spindle 6, a bearing sleeve 7, a thrust sleeve 8, a thrust ring 9, a locking nut 10, and two hydrostatic bearings. A shoulder 61 is provided at one end of the spindle 6. Two hydrostatic bearings are provided, which are relatively mounted on the front and rear ends of the spindle 6. The thrust sleeve 8 is mounted on the spindle 6 and is located between the two hydrostatic bearings. The thrust sleeve 8 presses the front hydrostatic bearing against the shoulder 61 of the spindle 6 to achieve positioning of the front hydrostatic bearing and the spindle 6. The thrust ring 9 is mounted on the end of the spindle 6 and presses the rear hydrostatic bearing against the axial end face of the thrust sleeve 8 to achieve positioning between the rear hydrostatic bearing and the spindle 6. The thrust ring 9 is locked by a locking nut 10. Each hydrostatic bearing is covered with a bearing sleeve 7, which is assembled into the support housing 5. It should be noted that a shallow annular groove is milled into the shoulder 61 of the main shaft 6 facing the hydrostatic bearing, the axial end faces of the thrust sleeve 8, and the end face of the thrust collar 9 facing the rear end of the hydrostatic bearing. This shallow annular groove, together with the third throttling edge of the axial throttle 4, forms a third slit throttle opening. In addition to milling shallow grooves, other positioning methods can also be used to ensure that a small gap is left between the shoulder of the main shaft 6, the thrust sleeve 8, the thrust collar 9, and the ends of the hydrostatic bearing to achieve the purpose of forming a slit throttle opening.

[0056] Figure 11Shows a schematic structural diagram of the support shell 5, combined with Figure 11 In this embodiment, the support housing 5 includes a front cover 51, a support sleeve 52, and a rear cover 53. The support sleeve 52 is mounted on the two bearing sleeves 7. The front cover 51 is mounted on the front end of the main shaft 6 and is connected to the front bearing sleeves 7, the front hydrostatic bearing, and the support sleeve 52 via long bolts. The rear cover 53 is mounted on the rear end of the main shaft 6 and is connected to the rear bearing sleeves 7, the rear hydrostatic bearing, and the support sleeve 52 via long bolts. This achieves the assembly of the support housing 5 with the bearing sleeves 7, the hydrostatic bearing, and the main shaft 6.

[0057] Combine Figure 11 The support sleeve 52 is provided with two main oil inlets 521 extending through the inner and outer walls. Two main oil inlet grooves 522 are provided on the inner wall of the support sleeve 52. Each main oil inlet 521 corresponds to a main oil inlet groove 522 and extends through the center of the corresponding main oil inlet groove 522. This connects the main oil inlets 521 and main oil inlet grooves 522, ensuring uniform distribution of the incoming oil. These two main oil inlets 521 and main oil inlet grooves 522 are used to provide equal amounts of pressurized oil to the two hydrostatic bearings.

[0058] Figure 12 Shows a schematic structural diagram of the bearing sleeve 7, combined with Figure 12 、 Figure 13 and Figure 14 In this embodiment, the bearing sleeve 7 is provided with two sleeve oil inlet holes 71. These two sleeve oil inlet holes 71 communicate with one of the main oil inlet grooves 522 on the support sleeve 52 and are located at opposite ends of the main oil inlet groove 522. This allows for synchronous oil supply to the two sleeve oil inlet holes 71 and equal distribution of pressurized oil. Two annular oil inlet grooves 72 are provided on the inner ring wall of the bearing sleeve 7. Each sleeve oil inlet hole 71 corresponds to and communicates with the corresponding annular oil inlet groove 72. One annular oil inlet groove 72 communicates with the first main oil passage 2 of the hydrostatic bearing, while the other annular oil inlet groove 72 communicates with the second main oil passage 45 of the hydrostatic bearing, respectively supplying oil to the radial throttle 1 and axial throttle 4 of the hydrostatic bearing. When the oil inlet amounts of the two annular oil inlet grooves 72 are the same, the oil inlet amount and oil inlet pressure of the first main oil passage 2 and the second main oil passage 45 are also the same, ensuring synchronous operation of the radial throttle 1 and axial throttle 4 of the hydrostatic bearing.

[0059] When the hydrostatic spindle structure is operating, oil is simultaneously supplied to the two main oil inlets 521 on the support housing 5. The pressurized oil is evenly distributed from the main oil inlet 521 and the main oil inlet groove 522 to the two sleeve oil inlet holes 71. The oil then flows from the two sleeve oil inlet holes 71 to the corresponding annular oil inlet grooves 72, and then from the two annular oil inlet grooves 72 to the first main oil passage 2 and the second main oil passage 45, respectively. This achieves synchronous oil supply to the radial throttle 1 and the axial throttle 4. At this time, a load-bearing oil film forms between the radial load-bearing oil chamber and the spindle 6, creating a pure liquid friction state between the inner side of the hydrostatic bearing and the spindle 6. A load-bearing oil film also forms between the axial load-bearing oil chamber and the engine body, creating a pure liquid friction state between the front and rear end faces of the hydrostatic bearing and the spindle 6 and the engine body. This improves the rotational accuracy and stability of the spindle 6.

[0060] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. An internal feedback hydrostatic bearing, provided with N pairs of throttles, characterized in that: The two throttles in each pair are respectively arranged on both sides of the radial direction and / or both sides of the axial direction of the main shaft for radial positioning and / or axial positioning of the main shaft; each throttle includes an oil inlet groove, an oil collecting groove and a bearing oil groove, the oil collecting groove is surrounded by the oil inlet groove, two opposite groove edges of the oil inlet groove are oil sealing edges, and the other two opposite groove edges are throttling edges, which are configured as gap throttling ports, and the pressure oil in the oil inlet groove can be pressed into the oil collecting groove from the gap throttling ports, and the groove edges around the oil collecting groove and the bearing oil groove are all oil sealing edges, and the oil collecting groove is connected to the bearing oil groove of the other throttle in the pair, and the pressure oil in the oil collecting groove is pressed into the bearing oil groove of the other throttle to achieve internal feedback.

2. The internal feedback hydrostatic bearing according to claim 1, characterized in that: The oil inlet groove is a long strip groove, the groove edges at both ends of the length direction of the oil inlet groove are oil sealing edges, and the groove edges at both ends of the width direction of the oil inlet groove are throttling edges.

3. The internal feedback hydrostatic bearing according to claim 1, characterized in that: The width of the oil sealing edge is greater than the width of the throttling edge.

4. The internal feedback hydrostatic bearing according to claim 1, characterized in that: The throttle further comprises an oil drain groove, into which the pressure oil in the bearing oil groove can be drained.

5. The internal feedback hydrostatic bearing according to claim 1, characterized in that: The throttle is a radial throttle used for radial positioning of the main shaft. The two paired radial throttles are respectively arranged on the inner ring wall of the hydrostatic bearing and are located on both sides of the central axis of the main shaft. The bearing oil groove of the radial throttle is surrounded by the oil collecting groove and extends along the axis direction of the hydrostatic bearing.

6. The internal feedback hydrostatic bearing according to claim 1, characterized in that: The throttle is an axial throttle for axial positioning of the main shaft. The two paired axial throttles are respectively arranged on the axial end faces of the hydrostatic bearing, and the bearing oil groove of the axial throttle is arranged between two adjacent oil collecting grooves.

7. The internal feedback hydrostatic bearing according to claim 5, characterized in that: The bearing oil groove of the axial throttle is an arc-shaped groove and extends along the circumferential direction of the hydrostatic bearing.

8. The internal feedback hydrostatic bearing according to claim 1, characterized in that: The four slit throttle ports in each pair of throttles and the two load-bearing oil grooves form a full-bridge hydraulic resistance network.

9. A static pressure spindle structure, characterized in that: It includes a supporting shell, a main shaft, a bearing sleeve, a thrust sleeve, a thrust ring, a locking nut and an internal feedback hydrostatic bearing as described in any one of claims 1 to 8; a shoulder is provided at one end of the main shaft, and two hydrostatic bearings are provided, and the two hydrostatic bearings are relatively sleeved on the front and rear ends of the main shaft, the thrust sleeve is sleeved on the main shaft and is located between the two hydrostatic bearings, the thrust sleeve presses the front hydrostatic bearing on the shoulder of the main shaft, the thrust ring is sleeved on the main shaft and presses the rear hydrostatic bearing on the thrust sleeve, and the thrust ring is locked by the locking nut; each hydrostatic bearing is covered with a bearing sleeve, and the bearing sleeve is assembled into the supporting shell.

10. The static pressure spindle structure according to claim 9, characterized in that: The throttle of the hydrostatic bearing includes a radial throttle and an axial throttle. Two total oil inlet grooves are provided on the inner wall of the supporting shell, and two total oil inlet ports corresponding to and communicating with the two total oil inlet grooves are provided on the supporting shell; two annular oil inlet grooves are provided on the inner ring wall of the bearing sleeve, and two shaft sleeve oil inlet holes corresponding to and communicating with the two annular oil inlet grooves are provided on the bearing sleeve, and the two shaft sleeve oil inlet holes are communicated with one of the total oil inlet grooves of the supporting shell; the two annular oil inlet grooves supply oil to the radial throttle and axial throttle of the hydrostatic bearing respectively.

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