Hydrostatic bearing set and high-speed hydrostatic spindle structure thereof

Abstract

The utility model relates to lathe main shaft technical field discloses a static pressure bearing group and its high -speed static pressure main shaft structure, including front static pressure bearing and rear static pressure bearing, have front radial pressure -bearing oil groove and axial pressure -bearing oil groove on front static pressure bearing, and be equipped with first stage oil return groove one between front radial pressure -bearing oil groove's and axial pressure -bearing oil groove, and the outside of front radial pressure -bearing oil groove is equipped with first stage oil return groove two and second stage oil return groove, and the outside of axial pressure -bearing oil groove is equipped with primary oil return groove and secondary oil return groove, have rear radial pressure -bearing oil groove and axial pressure -bearing gas groove on rear static pressure bearing, and one group rear first stage oil return groove and one group rear second stage oil return groove are equipped with on rear radial pressure -bearing oil groove both sides, and first throttling oil channel, second throttling oil channel, first oil return channel and second oil return channel in front static pressure bearing, and first air inlet channel, third throttling oil channel, third oil return channel and fourth oil return channel are equipped with in rear static pressure bearing. The utility model has the advantages of compact structure, high -speed, high rotation accuracy, long -life.

Description

Technical Field

[0001] This utility model relates to the field of machine tool spindle technology, and in particular to a hydrostatic bearing assembly and its high-speed hydrostatic spindle structure. Background Technology

[0002] High-speed, high-rigidity machine tool spindles are the main development direction of the machine tool industry. However, traditional machine tool spindles use rolling bearings as radial and axial supports during installation. When the spindle rotates, mechanical friction occurs between the machine tool spindle and the bearings, which limits the speed and rotational accuracy of the machine tool spindle.

[0003] Existing manufacturers have incorporated the support principle of hydrostatic bearings into machine tool spindles. For example, CN205798462U discloses a hydrostatic spindle. By installing an axial hydrostatic bearing and a front radial hydrostatic bearing at the front end of the spindle, and a rear radial hydrostatic bearing at the rear end, the front and rear axial hydrostatic grooves of the axial hydrostatic bearings form axial hydrostatic oil chambers on both sides of the spindle shoulder. The radial hydrostatic grooves of the front and rear radial hydrostatic bearings form radial hydrostatic oil chambers on the outside of the spindle. This allows the spindle to suspend in the oil film of each oil chamber. During spindle rotation, the hydrodynamic effect is used to achieve soft contact between the spindle and the bearings, thereby reducing the coefficient of friction between the spindle and the bearings. However, the aforementioned hydrostatic bearing assembly requires the machining of three hydrostatic bearings, resulting in a complex structure. In particular, the axial hydrostatic bearings require a separate bearing and hydrostatic cover installation method, leading to a large overall spindle size. Furthermore, each hydrostatic bearing end requires a skeleton seal, which still has physical contact with the spindle. This limits the hydrostatic bearing assembly to high-precision machining at low spindle speeds. Additionally, the skeleton seal has a limited service life and needs to be replaced after prolonged use, making maintenance inconvenient. Utility Model Content

[0004] To address the shortcomings of the existing technology, this utility model provides a hydrostatic bearing assembly and its high-speed hydrostatic spindle structure, which has the advantages of compact structure, high speed, high rotational accuracy, and long service life.

[0005] The technical solution of this utility model is as follows: a hydrostatic bearing assembly, comprising a front hydrostatic bearing disposed near the shaft shoulder and a rear hydrostatic bearing disposed near the shaft thrust portion. The front hydrostatic bearing has a front radial pressure bearing oil groove facing the shaft and an axial pressure bearing oil groove facing the shaft shoulder. A first-stage oil return groove is provided between the front sealing oil edge of the front radial pressure bearing oil groove and the inner sealing oil edge of the axial pressure bearing oil groove. A second-stage oil return groove and a third-stage oil return groove are sequentially provided along the rear sealing oil edge of the front radial pressure bearing oil groove in a direction away from the first-stage oil return groove. A primary oil return groove and a secondary oil return groove are sequentially provided along the axial pressure bearing oil groove in a direction away from the first-stage oil return groove. The rear hydrostatic bearing has a rear radial pressure bearing oil groove facing the shaft. The bearing includes a pressure-bearing oil groove and an axial pressure-bearing air groove facing the thrust portion. The two sealing oil edges of the rear radial pressure-bearing oil groove are provided with a set of rear primary oil return grooves and a set of rear secondary oil return grooves in sequence along the direction away from the center. The front hydrostatic bearing is provided with a first throttling oil passage for oil entering the front radial pressure-bearing oil groove, a second throttling oil passage for oil entering the axial pressure-bearing oil groove, a first return oil passage for oil returning from the first primary oil return groove, the second primary oil return groove and the primary oil return groove, and a second return oil passage for oil returning from the second primary oil return groove and the secondary oil return groove. The rear hydrostatic bearing is provided with a first air intake channel for air entering the axial pressure-bearing air groove, a third throttling oil passage for oil entering the rear radial pressure-bearing oil groove, a third return oil passage for oil returning from the rear primary oil return groove, and a fourth return oil passage for oil returning from the rear secondary oil return groove. The front radial pressure oil groove of the front hydrostatic bearing and the rear radial pressure oil groove of the rear hydrostatic bearing together provide radial oil pressure support for the spindle. The axial oil pressure provided by the axial pressure oil groove at the front end of the front hydrostatic bearing and the axial air pressure provided by the axial pressure air groove at the rear end of the rear hydrostatic bearing form axial balance, and oil film contact is formed in both the radial and axial directions at the working end of the spindle, ensuring the rigidity of the working end of the spindle. Compared with the existing three hydrostatic bearings, the structure is simpler and more compact. The first-stage oil return groove 1, the first-stage oil return groove 2 and the primary oil return groove located in the front hydrostatic bearing, and the second-stage oil return groove located in the rear hydrostatic bearing ensure the first-stage pressurized oil return of the oil film in the hydrostatic oil chamber. The first-stage oil return groove 2 and the secondary oil return groove located in the front hydrostatic bearing, and the second-stage oil return groove located in the rear hydrostatic bearing ensure the overflow oil return of the oil film after the first-stage pressurized oil return, thus forming a sealed oil return effect without the need for a skeleton. This achieves completely non-physical contact between the spindle and each hydrostatic bearing, improves the service life of the spindle, and meets the requirements of high speed and high rotational accuracy of the spindle.

[0006] The number of the front radial pressure bearing oil groove, the rear radial pressure bearing oil groove, the first throttling oil passage, the second throttling oil passage, and the third throttling oil passage is at least two. Each of the front radial pressure bearing oil grooves is circumferentially spaced inside the front hydrostatic bearing and corresponds one-to-one with the outlet of each of the first throttling oil passages. Each of the rear radial pressure bearing oil grooves is circumferentially spaced inside the rear hydrostatic bearing and corresponds one-to-one with the outlet of each of the third throttling oil passages. The outlets of each of the second throttling oil passages are circumferentially spaced inside the axial pressure bearing oil groove. A small orifice throttling device is installed at the inlet of each of the first throttling oil passages, the second throttling oil passages, and the third throttling oil passages. Small-hole throttles are installed at the inlet of each first, second, and third throttle oil passage. The hydraulic resistance of one throttle and the hydraulic resistance of the oil film in the corresponding pressure-bearing oil groove form a series hydraulic circuit. Regardless of whether the spindle is subjected to radial or axial force, the pressure can be self-balanced and adjusted to ensure the normal operation of the spindle within the rated load and effectively guarantee the spindle's rotational accuracy.

[0007] The primary oil return groove is provided with a first oil baffle ring and a second oil baffle ring in sequence along the axial direction on the front hydrostatic bearing on the side away from the first oil return channel. An annular oil return channel is formed between the first oil baffle ring and the primary oil return groove. The secondary oil return groove is located between the first oil baffle ring and the second oil baffle ring.

[0008] The second oil baffle ring has an air seal groove in the middle, and the front hydrostatic bearing has a second air intake channel for air to enter the air seal groove. Gas enters the air seal groove through the second air intake channel, forming an air curtain on the side of the front hydrostatic bearing near the working end of the spindle, which can effectively prevent debris generated during spindle grinding from entering the secondary oil return groove.

[0009] An air seal cover is fixed to the outer side of the front end of the front hydrostatic bearing. The air seal cover and the front hydrostatic bearing together form an annular air chamber that communicates with the second air intake channel. The annular air chamber is connected to an external air source.

[0010] The first oil return passage consists of several radially distributed circumferentially within the front hydrostatic bearing. The third oil return passage consists of several radially distributed circumferentially within the rear hydrostatic bearing. The inlet of the second oil return passage is located on the periphery of the lowest position of the front secondary oil return groove and the secondary oil return groove of the assembled front hydrostatic bearing. The inlet of the fourth oil return passage is located on the periphery of the lowest point of the rear secondary oil return groove of the assembled rear hydrostatic bearing.

[0011] This utility model also provides a high-speed hydrostatic spindle structure, including a spindle, a rotor fixed in the middle of the spindle, a thrust piston fixed on the outside of the non-working end of the spindle, a housing having a stator that mates with the rotor, and the aforementioned hydrostatic bearing assembly. A front shoulder is formed on the outside of the working end of the spindle, forming the shoulder portion. The thrust piston forms the thrust portion. The front hydrostatic bearing and the rear hydrostatic bearing are respectively fixed at both ends of the housing. The front hydrostatic bearing has a front groove at its front end for axial movement of the shoulder portion. The rear hydrostatic bearing has a rear end groove for circumferential movement of the thrust piston. The housing has a forward oil passage connected to the first throttling oil passage and the second throttling oil passage, a rear oil inlet passage connected to the third throttling oil passage, an air supply passage connected to the first air inlet passage, a first-stage return oil passage connected to the first return oil passage, a first-stage return oil passage connected to the second return oil passage, a second-stage return oil passage connected to the third return oil passage, and a second-stage return oil passage connected to the fourth return oil passage.

[0012] The housing is connected to the rear hydrostatic bearing via a hydrostatic bearing seat. The surface of the hydrostatic bearing seat is provided with a rear annular oil inlet groove. The rear annular oil inlet groove is connected to the third throttling oil passage via a rear oil supply channel. The surface of the front hydrostatic bearing is provided with a front annular oil inlet groove. The inlets of the first throttling oil passage and the second throttling oil passage are located within the front annular oil inlet groove. The inner wall of the housing and the front annular oil inlet groove together form a front annular oil inlet passage connected to the forward oil supply channel. The inner wall of the housing and the rear annular oil inlet groove together form a rear annular oil inlet passage connected to the rear oil supply channel.

[0013] The surface of the rear hydrostatic bearing is provided with a primary oil groove for connecting two third oil passages corresponding to the positions on the two rear primary oil return grooves, and a secondary oil groove for connecting two fourth oil passages corresponding to the positions on the two rear secondary oil return grooves. The hydrostatic bearing housing is provided with a fifth oil passage for connecting the primary oil groove and the rear primary oil return channel, and a sixth oil passage for connecting the secondary oil groove and the rear secondary oil return channel.

[0014] A rear axle shoulder is formed on the outer side of the non-working end of the spindle. One end of the thrust piston abuts against the rear axle shoulder, and the other end of the thrust bearing is pressed and fixed by a piston cap fixed on the non-working end of the spindle.

[0015] In summary, the present invention has the following main advantages: This invention provides radial and axial hydraulic support to the spindle by providing a front radial hydraulic groove and an axial hydraulic groove on the front hydrostatic bearing, and a rear radial hydraulic groove and an axial hydraulic air groove on the rear hydrostatic bearing. The front and rear radial hydraulic grooves together provide radial hydraulic support to the spindle, while the axial hydraulic pressure from the axial hydraulic groove and the axial air pressure from the axial hydraulic air groove create axial balance. This ensures oil film contact in both the radial and axial directions at the working end of the spindle, guaranteeing its rigidity. Compared to existing three-hydrostatic bearings, this structure is simpler and more compact. The first-stage oil return groove 1, the first-stage oil return groove 2, and the primary oil return groove of the front hydrostatic bearing, and the second-stage oil return groove of the rear hydrostatic bearing, ensure the first-stage pressurized oil return to the oil film in the hydrostatic oil chamber. The first-stage oil return groove 2 and the secondary oil return groove of the front hydrostatic bearing, and the second-stage oil return groove of the rear hydrostatic bearing, ensure the overflow oil return after the first-stage pressurized oil return. This forms a sealed oil return effect without the need for a frame, realizing complete non-physical contact between the spindle and each hydrostatic bearing, improving the service life of the spindle, and meeting the requirements of high speed and high rotational accuracy of the spindle. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the front hydrostatic bearing in this utility model; Figure 2 This is a structural schematic diagram of the front hydrostatic bearing in this utility model from another angle; Figure 3 This is a front view of the front hydrostatic bearing in this utility model; Figure 4 It is along Figure 3 A cross-sectional view along the AA direction; Figure 5 It is along Figure 3 A cross-sectional view along the BB direction; Figure 6 It is along Figure 3 A cross-sectional view along the CC direction; Figure 7 It is along Figure 3 A cross-sectional view along the DD direction; Figure 8 This is a schematic diagram of the structure of the rear hydrostatic bearing in this utility model; Figure 9 This is a structural schematic diagram of the rear hydrostatic bearing of this utility model from another angle; Figure 10 This is a front view of the rear hydrostatic bearing in this utility model; Figure 11 It is along Figure 10 Cross-sectional view along the EE direction; Figure 12 It is along Figure 10 A cross-sectional view along the FF direction; Figure 13 It is along Figure 10 A cross-sectional view along the GG direction; Figure 14 This is a schematic diagram of the hydrostatic spindle in this utility model; Figure 15 This is a cross-sectional view of the hydrostatic spindle along the longitudinal axis of this utility model; Figure 16 This is a cross-sectional view of the hydrostatic spindle along the transverse plane where the center of the first-stage oil return channel and the center of the second-stage oil return channel are located in this utility model. Figure 17 This is a cross-sectional view of the hydrostatic spindle along the transverse plane containing the center of the first-stage oil return channel and the center of the second-stage oil return channel in this utility model.

[0017] Reference numerals: 1. Front hydrostatic bearing; 101. Front radial pressure bearing oil groove; 1011. First throttling oil passage; 102. Axial pressure bearing oil groove; 1021. Second throttling oil passage; 103. First stage return oil groove one; 1031. First return oil passage a; 104. First stage return oil groove two; 1041. First return oil passage b; 105. Front second stage return oil groove; 1051. Second return oil passage a; 106. Primary return oil groove; 1061. First return oil passage c; 107. Secondary return oil groove. Oil groove; 1071, Second oil return passage b; 108, First main oil return passage; 109, Front annular oil inlet groove; 110, First oil baffle ring; 111, Annular oil return passage; 112, Second oil baffle ring; 113, Air seal groove; 114, Second air intake passage; 2, Rear hydrostatic bearing; 201, Rear radial pressure bearing oil groove; 2011, Third throttling oil passage; 202, Axial pressure bearing air groove; 2021, First air intake passage; 203, Rear primary oil return groove; 2031, Third 1. Oil return passage; 204. Rear secondary oil return groove; 2041. Fourth oil return passage; 205. Primary oil groove; 206. Secondary oil groove; 207. Annular air inlet groove; 3. Gas seal cover; 301. Annular air chamber; 4. Hydrostatic bearing housing; 401. Rear oil supply passage; 402. Rear annular oil inlet groove; 403. Fifth oil return passage; 404. Sixth oil return passage; 405. Rear primary oil collection groove; 406. Rear secondary oil collection groove; 5. Main shaft; 501. Front axle shoulder; 502. Rear axle 6. Shoulder; 6. Housing; 601. Inlet oil passage; 602. Rear oil passage; 603. Air supply passage; 604. First-stage return oil passage; 605. First-stage return oil passage; 6051. Second return oil connecting branch; 606. Rear-stage return oil passage; 607. Rear-stage return oil passage; 608. Air source connector; 609. First-stage oil collection trough; 610. First-stage oil collection trough; 7. Thrust piston; 8. Piston gland; 9. Grinding wheel; 10. Rotor; 11. Stator. Detailed Implementation

[0018] The technical solutions of the present utility model will be described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments.

[0019] In the following description, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this utility model, unless otherwise stated, "a plurality of" means two or more.

[0020] Furthermore, in this utility model, the directional terms "front" and "rear" are relative to the working end direction of the spindle, that is, the direction closer to the working end of the spindle is "front" and the direction farther away from the working end of the spindle is "rear". The directional terms "inner" and "outer" are relative to the center direction of the spindle, that is, the direction closer to the center of the spindle is "inner" and the direction farther away from the center of the spindle is "outer".

[0021] like Figure 1 and Figure 8 As shown, this utility model provides a hydrostatic bearing assembly, including a front hydrostatic bearing 1 disposed near the shoulder of the main shaft 5 and a rear hydrostatic bearing 2 disposed near the thrust portion of the main shaft 5, as follows. Figure 1 As shown, the front hydrostatic bearing 1 has a front radial pressure bearing oil groove 101 facing the main shaft 5 and an axial pressure bearing oil groove 102 facing the shaft shoulder. A first-stage return oil groove 103 is provided between the front sealing oil edge of the front radial pressure bearing oil groove 101 and the inner sealing oil edge of the axial pressure bearing oil groove 102. In this design, the first-stage return oil groove 103 is a radial groove formed on the front sealing oil edge of the front radial pressure bearing oil groove 101, with one side extending to the inner sealing oil edge of the axial pressure bearing oil groove; thus forming a chamber for the oil film in the front radial pressure bearing oil groove 101 and the oil film in the axial pressure bearing oil groove to return oil together. The axial pressure bearing oil groove 102 has a primary return oil groove 106 and a secondary return oil groove 107 sequentially arranged in a direction away from the first-stage return oil groove 103, as shown in the diagram. Figure 2 As shown, the front radial pressure oil groove 101 has a front first-stage oil return groove 104 and a front second-stage oil return groove 105 sequentially arranged along the rear sealing edge away from the front first-stage oil return groove 103, as shown. Figure 8 and Figure 9 As shown, the rear hydrostatic bearing 2 has a rear radial pressure bearing oil groove 201 facing the main shaft 5 and an axial pressure bearing air groove 202 facing the thrust portion. The two oil-sealing edges of the rear radial pressure bearing oil groove 201 are sequentially provided with a set of rear primary oil return grooves 203 and a set of rear secondary oil return grooves 204 along the direction away from the center. Figures 3-7As shown, the front hydrostatic bearing 1 is provided with a first throttling oil passage 1011 for oil entering the front radial pressure bearing oil groove 101, a second throttling oil passage 1021 for oil entering the axial pressure bearing oil groove 102, a first return oil passage for oil returning from the first-stage return oil groove 103, the second-stage return oil groove 104 and the primary return oil groove 106, and a second return oil passage for oil returning from the second-stage return oil groove 105 and the secondary return oil groove 107, wherein, as Figure 6 As shown, the first oil return passage includes a first oil return passage b1041 with its inlet located in the first-stage oil return groove 104 and radially penetrating the front hydrostatic bearing 1; a first oil return passage c1061 with its inlet located in the secondary oil return groove 107 and axially penetrating the front hydrostatic bearing 1; and a first oil return passage a1031 with its inlet located in the first-stage oil return groove 103 and obliquely penetrating into the first oil return passage c1061. These three passages ultimately converge at the penetration opening of the first oil return passage b1041 on the surface of the front hydrostatic bearing 1, forming the first main oil return passage 108. The penetration opening of the first oil return passage c1061 at the rear end of the front hydrostatic bearing 1 is sealed by an oil plug. Figure 7 As shown, the second oil return passage includes a second oil return passage a1051 with its inlet located in the first secondary oil return groove 105 and a second oil return passage b1071 with its inlet located in the secondary oil return groove 107. These two passages are separately installed on the front hydrostatic bearing 1. Figure 10-13 As shown, the rear hydrostatic bearing 2 is provided with a first air intake channel 2021 for air intake into the axial pressure bearing air groove 202, a third throttling oil passage 2011 for oil intake into the rear radial pressure bearing oil groove 201, a third return oil passage 2031 for oil return into the rear first-stage return oil groove 203, and a fourth return oil passage 2041 for oil return into the rear second-stage return oil groove 204.

[0022] The oil film formed in the front radial bearing oil groove 101 of the front hydrostatic bearing 1 and the rear radial bearing oil groove 201 of the rear hydrostatic bearing 2 together provides radial hydraulic support for the spindle 5. The oil pressure formed in the axial bearing oil groove 102 at the front end of the front hydrostatic bearing 1 and the air pressure formed in the axial bearing air groove 202 at the rear end of the rear hydrostatic bearing 2 provide axial balance for the spindle 5 and ensure that oil film contact is formed in both the radial and axial directions at the working end of the spindle 5, thus ensuring the rigidity of the working end of the spindle 5. Compared with the existing triple hydrostatic bearing, the structure of the double hydrostatic bearing is simpler and more compact, and it is located in front of the front hydrostatic bearing 1. The primary oil return groove 103, the first primary oil return groove 104, the primary oil return groove 106, and the second primary oil return groove 203 located in the rear hydrostatic bearing 2 ensure the first-stage pressurized oil return to the oil film in the hydrostatic oil chamber. The first secondary oil return groove 105 and the secondary oil return groove 107 located in the front hydrostatic bearing 1, and the second secondary oil return groove 204 located in the rear hydrostatic bearing 2 ensure the overflow oil return after the first-stage pressurized oil return. This forms a sealed oil return effect without the need for a skeleton, realizing complete non-physical contact between the spindle 5 and each hydrostatic bearing, improving the service life of the spindle 5, and meeting the requirements of high speed and high rotational accuracy of the spindle 5.

[0023] More preferably, the number of the front radial pressure-bearing oil groove, the rear radial pressure-bearing oil groove, the first throttling oil passage 1011, the second throttling oil passage 1021, and the third throttling oil passage 2011 is at least two. Specifically, in this solution, for example... Figure 3 As shown, there are four front radial pressure bearing oil grooves 101 and four first throttling oil passages 1011. Each front radial pressure bearing oil groove is circumferentially spaced on the inner side of the front hydrostatic bearing 1 and corresponds one-to-one with the outlet of each first throttling oil passage 1011; as shown Figure 10 As shown, there are four rear radial pressure bearing oil grooves 201 and three throttling oil passages 2011. Each rear radial pressure bearing oil groove is circumferentially spaced inside the rear hydrostatic bearing 2 and corresponds one-to-one with the outlet of each third throttling oil passage 2011. Figure 3As shown, there are three second throttling oil passages 1021. The outlets of each second throttling oil passage 1021 are distributed circumferentially within the axial pressure-bearing oil groove 102. To ensure the throttling effect of each throttling oil passage, a small-hole throttler is installed at the inlet of each first throttling oil passage 1011, each second throttling oil passage 1021, and each third throttling oil passage 2011. Through the small-hole throttler, the hydraulic resistance of any throttling oil passage and the hydraulic resistance of the oil film at the corresponding pressure-bearing oil groove form a series hydraulic circuit. For example, when subjected to radial force, the gap between the sealing edge of the front radial pressure-bearing oil groove 101 / rear radial pressure-bearing oil groove 201 facing the force side and the main shaft 5 decreases, and the hydraulic resistance of the internal oil film decreases. When the pressure is large, the hydraulic resistance of the small-hole throttle at the inlet of the first throttling oil passage 1011 / the third throttling oil passage 2011 decreases, thereby increasing the amount of oil entering the corresponding front radial pressure bearing oil groove 101 / rear radial pressure bearing oil groove 201 to balance the radial force. Similarly, when axial force is applied, the gap between the sealing edge of the axial pressure bearing oil groove 102 and the shaft shoulder decreases, and the internal oil film hydraulic resistance increases. This reduces the hydraulic resistance of the small-hole throttle at the inlet of the second throttling oil passage 1021, increasing the amount of oil entering the axial pressure bearing oil groove 102 to balance the axial force. Through the self-balancing adjustment of pressure, the normal operation of the spindle 5 within the rated load is ensured, thereby effectively guaranteeing the rotational accuracy of the spindle 5.

[0024] Further preferred, in order to improve the oil return sealing effect, such as Figure 3 and Figure 10 As shown, there are several first oil return channels radially distributed circumferentially within the front hydrostatic bearing 1, and several third oil return channels 2031 radially distributed circumferentially within the rear hydrostatic bearing 2. These channels provide circumferential return for the pressurized oil flowing from the sealing edge within the axial pressure oil groove 102, the front radial pressure oil groove 101, and the rear radial pressure oil groove 201. After circumferential return through the first and third oil return channels 2031, the oil overflowing from the first-stage oil return groove 104 enters the first-stage oil return groove 105, and the oil overflowing from the primary oil return groove 106 enters the secondary oil return groove 107. The aforementioned oil, without pressure, will accumulate in the corresponding oil return grooves. The inlet of the second oil return channel a1051 is located at the bottom of the groove, and the inlet of the second oil return channel b1071 is located at the lowest point of the secondary oil return groove 107 after assembly. Similarly, the inlet of the fourth oil return channel 2041 is located at the lowest point of the secondary oil return groove 204 after assembly. More preferably, there are two of the above-mentioned second oil return channels a1051, second oil return channel b1071 and fourth oil return channel 2041, which are symmetrically arranged on both sides of their respective lowest points to increase the maximum oil return volume by gravity.

[0025] Further preferred, such as Figure 5 and Figure 6 As shown, the primary oil return groove 106 is radially arranged outside the axial pressure oil groove 102. On the front hydrostatic bearing 1 on the side of the primary oil return groove 106 away from the first oil return channel, a first oil baffle ring 110 and a second oil baffle ring 112 are arranged in sequence along the axial direction. The first oil baffle ring 110 and the primary oil return groove 106 form an annular oil return channel 111, so that the pressurized oil flowing from the axial pressure oil groove 102 to the primary oil return groove 106 can flow out more fully from the first oil return channel c1061. The secondary oil return groove 107 is located between the first oil baffle ring 110 and the second oil baffle ring 112.

[0026] Because the grinding wheel 9 is mounted on the working end of the spindle 5, metal shavings are generated during grinding. To prevent these shavings from entering the oil return groove and affecting the normal operation of the spindle 5, such as... Figure 4 As shown, the second oil baffle ring 112 has an air seal groove 113 in the middle, and the front hydrostatic bearing 1 has a second air intake channel 114 for air intake into the air seal groove 113. More preferably, an air seal cover 3 is fixed on the outer side of the front end of the front hydrostatic bearing 1. The air seal cover 3 and the front hydrostatic bearing 1 together form an annular air chamber 301 that communicates with the second air intake channel 114. The annular air chamber 301 is connected to an external air source via an air source connector 608. There are several second air intake channels 114, which are radially distributed in the circumferential direction on the front hydrostatic bearing 1 corresponding to the annular air chamber 301. After the external air source enters the annular air chamber 301, it is evenly filled and enters the air seal groove 113 through each second air intake channel 114, forming an air curtain on the second oil baffle ring 112, thereby effectively blocking flying debris.

[0027] like Figure 15 As shown, this utility model also provides a high-speed hydrostatic spindle structure, including a spindle 5, a rotor 10 fixed in the middle of the spindle 5, a thrust piston 7 fixed on the outside of the non-working end of the spindle 5, a housing 6 having a stator 11 that mates with the rotor 10, and the aforementioned hydrostatic bearing assembly. A front shoulder 501 is formed on the outside of the working end of the spindle 5, forming the shoulder portion, and the thrust piston 7 forms the thrust portion. The front hydrostatic bearing 1 and the rear hydrostatic bearing 2 are respectively fixed at both ends of the housing 6. The front hydrostatic bearing 1 has a front groove for axial movement of the shoulder portion at its front end, and an axial pressure oil groove 102, a primary oil return groove 106, a secondary oil return groove 107, a first oil retainer ring 110, and a second oil retainer ring 112 are all located within the front groove. The rear hydrostatic bearing 2 has a rear groove for circumferential movement of the thrust piston 7 at its rear end, and an axial pressure air groove 202 is located within the rear groove. Figure 14As shown, the housing 6 has a forward oil passage 601 connected to the first throttling oil passage 1011 and the second throttling oil passage 1021, a rear oil passage 602 connected to the third throttling oil passage, an air supply passage 603 connected to the first air intake passage 2021, a first-stage return oil passage 604 connected to the first return oil passage, a first-stage return oil passage 605 connected to the second return oil passage, a rear-stage return oil passage 606 connected to the third return oil passage 2031, and a rear-stage return oil passage 607 connected to the fourth return oil passage 2041.

[0028] Further preferably, to facilitate the installation of the thrust piston 7, such as Figure 15 As shown, a rear shoulder 502 is formed on the outer side of the non-working end of the main shaft 5. One end of the thrust piston 7 abuts against the rear shoulder 502, and the other end of the thrust bearing is pressed and fixed by a piston cap 8 fixed on the non-working end of the main shaft 5.

[0029] Further preferably, to facilitate the installation of the rear hydrostatic bearing 2, a hydrostatic bearing housing 4 is sealed and fixed to the outside of the rear hydrostatic bearing 2, and is fixedly connected to the rear end of the housing 6 via the hydrostatic bearing housing 4. Specifically, as shown in... Figure 15 As shown, the surface of the hydrostatic bearing housing 4 is provided with a rear annular oil inlet groove 402. The rear annular oil inlet groove 402 is connected to each of the third throttling oil passages via multiple rear oil supply channels 401. The inner wall of the housing 6 and the rear annular oil inlet groove 402 together form a rear annular oil inlet channel connected to the rear oil inlet channel 602. Figure 2 As shown, the front hydrostatic bearing 1 has a front annular oil inlet groove 109 on its surface. The inlets of the first throttling oil passage 1011 and the second throttling oil passage 1021 are located within the front annular oil inlet groove 109. Figure 15 As shown, the inner wall of the housing 6 and the front annular oil inlet groove 109 together form a front annular oil inlet channel connected to the forward oil passage 601. Of course, in order to ensure uniform pressure application within the axial pressure-bearing air groove 202, such as... Figure 9 and Figure 11 As shown, there are several first air intake channels 2021, which are radially distributed along the circumference on the rear end groove of the rear hydrostatic bearing 2. An annular air intake groove 207 is provided on the outer side of the rear end groove. The inlet of each first air intake channel 2021 is located on the annular air intake groove 207. The inner wall of the hydrostatic bearing seat 4 and the annular air intake groove 207 together form an annular air passage connected to the air supply channel 603.

[0030] Further preferred, such as Figure 9 , Figure 12 and Figure 13As shown, the surface of the rear hydrostatic bearing 2 is provided with a primary oil groove 205 for connecting two corresponding third oil return passages 2031 on two rear primary oil return grooves 203, and a secondary oil groove 206 for connecting two corresponding fourth oil return passages 2041 on two rear secondary oil return grooves 204. Figure 17 As shown, the hydrostatic bearing housing 4 is provided with a fifth oil return channel 403 for connecting the primary oil tank 205 and the subsequent primary oil return channel 606, and a sixth oil return channel 404 for connecting the secondary oil tank 206 and the subsequent secondary oil return channel 607. Specifically, since there are several third oil return channels 2031, there are also several corresponding primary oil tanks 205 and fifth oil return channels 403. In order to facilitate the centralized collection of pressurized oil from each fifth oil return channel 403 into the subsequent primary oil return channel 606, the surface of the hydrostatic bearing housing 4 is provided with... A secondary oil collection trough 405 is provided, which, together with the housing 6, forms a rear arc-shaped oil collection cavity connected to the secondary oil return channel 606. The outlets of each fifth oil return channel 403 are located within the secondary oil collection trough 405. A secondary oil collection trough 406 is provided at the corresponding positions of the hydrostatic bearing seat 4 and the sixth oil return channel 404. The secondary oil return channel 607 is horizontally positioned at the bottom of the housing 6 to accommodate the gravity return of oil from the fourth oil return channel 2041 to the secondary oil trough 206, then to the sixth oil return channel 404, and finally to the secondary oil collection trough 406. Similarly, as... Figure 16 As shown, in order to collect the pressurized oil from each of the first return oil passages into the preceding stage return oil channel 604, a preceding stage oil collecting groove 609 is provided inside the housing 6. This groove, together with the front hydrostatic bearing 1, forms a front arc-shaped oil collecting chamber connected to the preceding stage return oil channel 604. The first return oil main passage 108 of each of the first return oil passages is located within the front arc-shaped oil collecting chamber. Figure 15 As shown, the inner side of the housing 6 is provided with a front secondary oil collecting groove 610 corresponding to the outlet position of the second oil return passage a1051, and a second oil return connecting branch 6051 arranged axially and connected to the outlet of the front secondary oil collecting groove 610 and the second oil return passage b1071. The front secondary oil return passage 605 is horizontally arranged at the bottom of the housing 6 to accommodate the gravity oil return of the second oil return passage a1051 / second oil return passage b1071-front secondary oil collecting groove 610.

[0031] like Figures 15-17 As shown, the oil inlet path, oil return path, and air intake path of this hydrostatic spindle structure are described in detail.

[0032] The oil inlet path of the front hydrostatic bearing 1: Hydraulic oil enters the front annular oil inlet groove 109 through the forward oil passage 601. Part of the hydraulic oil enters the front radial pressure bearing oil groove 101 through the first throttling oil passage 1011 to form an oil film, generating radial buoyancy on the spindle 5. The other part of the hydraulic oil enters the axial pressure bearing oil groove 102 through the second throttling oil passage 1021 to form an oil film, generating forward axial force on the spindle 5. The oil return path of the front hydrostatic bearing 1: Hydraulic oil in each front radial pressure bearing oil groove 101 enters the first-stage return oil groove 104 through the rear sealing oil edge on one side, and enters the second-stage return oil groove 104 through the front sealing oil edge on the other side. 2. The return oil generated by the inner sealing oil edge enters the first-stage oil return tank 1 together, and the return oil generated by the axial pressure oil tank through the outer sealing oil edge enters the primary oil return tank. The three flow into the first return oil main passage 108 and into the front arc-shaped oil collection cavity, and are discharged through the first-stage return oil channel 604. The oil overflowing from the first-stage return oil tank 2 104 enters the first-stage return oil tank 105, and the oil overflowing from the annular return oil channel 111 of the primary return oil tank 106 enters the secondary return oil tank 107. The two flow into the first-stage return oil tank 105 under the action of gravity and are discharged through the first-stage return oil channel 605.

[0033] The oil inlet route of the rear hydrostatic bearing 2: Hydraulic oil enters the rear annular oil inlet groove 402 through the rear oil inlet channel 602, and then enters the rear radial pressure bearing oil groove 201 through each rear upper oil channel 401 and the third throttling oil channel 2011 to form an oil film, generating radial buoyancy on the main shaft 5; The oil return route of the rear hydrostatic bearing 2: Hydraulic oil in each rear radial pressure bearing oil groove 201 enters the rear first-stage return oil groove 203 through the sealing oil edge on both sides, and then flows into the first-stage oil groove 205 through the third return oil channel 2031, and flows into the rear arc-shaped oil collecting chamber through the fifth return oil channel 403, and is discharged through the rear first-stage return oil channel 606; The oil overflowing from the rear first-stage return oil groove 203 enters the rear second-stage return oil groove 204, and under the action of gravity, flows into the rear second-stage return oil groove 204 through the fourth return oil channel 2041, the second-stage oil groove 206, and the sixth return oil channel 404 in sequence, and is discharged through the rear second-stage return oil channel 607.

[0034] The air intake route of the rear hydrostatic bearing 2: Compressed air enters the annular intake groove 207 through the air supply channel 603, and enters the axial pressure groove 202 through the first intake channel 2021, pushing the thrust piston 7 to move backward, thereby generating a rearward axial force on the spindle 5. The resultant force of this force and the forward axial force generated by the oil film in the axial pressure groove 102 is zero, thereby achieving axial balance of the spindle 5. In addition, the compressed air source also enters the annular air chamber 301 of the air seal cover 3 through the air source connector 608, and enters the air seal groove 113 of the front hydrostatic bearing 1 through the second gas channel, realizing the air curtain protection of the working end of the spindle 5.

[0035] The entire hydrostatic spindle structure is compact and uses a non-contact seal, which effectively improves the service life of spindle 5 and meets the requirements of high speed and high rotational accuracy of spindle 5.

[0036] The above description is merely a preferred embodiment of this utility model and is not intended to limit the scope of this utility model. Various modifications and variations can be made to this utility model by those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the principles of this utility model should be included within the protection scope of this utility model.

Claims

1. A hydrostatic bearing assembly, comprising a front hydrostatic bearing disposed near the shoulder of the main shaft and a rear hydrostatic bearing disposed near the thrust portion of the main shaft, characterized in that, The front hydrostatic bearing has a front radial pressure bearing oil groove facing the main shaft and an axial pressure bearing oil groove facing the shaft shoulder. A first-stage return oil groove is provided between the front sealing oil edge of the front radial pressure bearing oil groove and the inner sealing oil edge of the axial pressure bearing oil groove. A second-stage return oil groove and a third-stage return oil groove are sequentially provided along the rear sealing oil edge of the front radial pressure bearing oil groove in a direction away from the first-stage return oil groove. A primary return oil groove and a secondary return oil groove are sequentially provided along the direction away from the first-stage return oil groove. The rear hydrostatic bearing has a rear radial pressure bearing oil groove facing the main shaft and an axial pressure bearing air groove facing the thrust portion. The rear radial pressure bearing oil... The two sealing edges of the groove are provided with a set of first-stage return oil grooves and a set of second-stage return oil grooves in sequence away from the center. The front hydrostatic bearing is provided with a first throttling oil passage for oil entering the front radial pressure oil groove, a second throttling oil passage for oil entering the axial pressure oil groove, a first return oil passage for oil returning from the first-stage return oil groove, the second-stage return oil groove and the primary return oil groove, and a second return oil passage for oil returning from the second-stage return oil groove and the secondary return oil groove. The rear hydrostatic bearing is provided with a first air intake channel for air entering the axial pressure air groove, a third throttling oil passage for oil entering the rear radial pressure oil groove, a third return oil passage for oil returning from the first-stage return oil groove, and a fourth return oil passage for oil returning from the second-stage return oil groove.

2. The hydrostatic bearing assembly according to claim 1, characterized in that, The number of the front radial pressure bearing oil groove, the rear radial pressure bearing oil groove, the first throttling oil passage, the second throttling oil passage, and the third throttling oil passage is at least two. Each of the front radial pressure bearing oil grooves is circumferentially spaced inside the front hydrostatic bearing and corresponds one-to-one with the outlet of each of the first throttling oil passages. Each of the rear radial pressure bearing oil grooves is circumferentially spaced inside the rear hydrostatic bearing and corresponds one-to-one with the outlet of each of the third throttling oil passages. The outlets of each of the second throttling oil passages are circumferentially spaced inside the axial pressure bearing oil groove. A small orifice throttling device is installed at the inlet of each of the first throttling oil passages, the second throttling oil passages, and the third throttling oil passages.

3. A hydrostatic bearing assembly according to claim 1 or 2, characterized in that, The primary oil return groove is provided with a first oil baffle ring and a second oil baffle ring in sequence along the axial direction on the front hydrostatic bearing on the side away from the first oil return channel. An annular oil return channel is formed between the first oil baffle ring and the primary oil return groove. The secondary oil return groove is located between the first oil baffle ring and the second oil baffle ring.

4. A hydrostatic bearing assembly according to claim 3, characterized in that, The second oil baffle ring has an air seal groove in the middle, and the front hydrostatic bearing has a second air intake channel for air to enter the air seal groove.

5. A hydrostatic bearing assembly according to claim 4, characterized in that, An air seal cover is fixed to the outer side of the front end of the front hydrostatic bearing. The air seal cover and the front hydrostatic bearing together form an annular air chamber that communicates with the second air intake channel. The annular air chamber is connected to an external air source.

6. A hydrostatic bearing assembly according to claim 1, 2, 4, or 5, characterized in that, The first oil return passage consists of several radially distributed circumferentially within the front hydrostatic bearing. The third oil return passage consists of several radially distributed circumferentially within the rear hydrostatic bearing. The inlet of the second oil return passage is located on the periphery of the lowest position of the front secondary oil return groove and the secondary oil return groove of the assembled front hydrostatic bearing. The inlet of the fourth oil return passage is located on the periphery of the lowest point of the rear secondary oil return groove of the assembled rear hydrostatic bearing.

7. A high-speed hydrostatic spindle structure, comprising a spindle, a rotor fixed in the middle of the spindle, a thrust piston fixed on the outside of the non-working end of the spindle, a housing having a stator that mates with the rotor, and a hydrostatic bearing assembly as described in any one of claims 1-6, wherein a front shoulder is formed on the outside of the working end of the spindle, the front shoulder forming the shoulder portion, the thrust piston forming the thrust portion, the front hydrostatic bearing and the rear hydrostatic bearing are respectively fixed at both ends of the housing, and the front hydrostatic bearing has a front groove at its front end for axial movement of the shoulder portion. The rear hydrostatic bearing has a rear groove for the thrust piston to move circumferentially. The housing has a forward oil passage connected to the first throttling oil passage and the second throttling oil passage, a rear oil inlet passage connected to the third throttling oil passage, an air supply passage connected to the first air inlet passage, a first-stage return oil passage connected to the first return oil passage, a first-stage return oil passage connected to the second return oil passage, a second-stage return oil passage connected to the third return oil passage, and a second-stage return oil passage connected to the fourth return oil passage.

8. The high-speed hydrostatic spindle structure according to claim 7, characterized in that, The housing is connected to the rear hydrostatic bearing via a hydrostatic bearing seat. The surface of the hydrostatic bearing seat is provided with a rear annular oil inlet groove. The rear annular oil inlet groove is connected to the third throttling oil passage via a rear oil supply channel. The surface of the front hydrostatic bearing is provided with a front annular oil inlet groove. The inlets of the first throttling oil passage and the second throttling oil passage are located within the front annular oil inlet groove. The inner wall of the housing and the front annular oil inlet groove together form a front annular oil inlet passage connected to the forward oil supply channel. The inner wall of the housing and the rear annular oil inlet groove together form a rear annular oil inlet passage connected to the rear oil supply channel.

9. A high-speed hydrostatic spindle structure according to claim 8, characterized in that, The surface of the rear hydrostatic bearing is provided with a primary oil groove for connecting two third oil passages corresponding to the positions on the two rear primary oil return grooves, and a secondary oil groove for connecting two fourth oil passages corresponding to the positions on the two rear secondary oil return grooves. The hydrostatic bearing housing is provided with a fifth oil passage for connecting the primary oil groove and the rear primary oil return channel, and a sixth oil passage for connecting the secondary oil groove and the rear secondary oil return channel.

10. A high-speed hydrostatic spindle structure according to claim 7, characterized in that, A rear axle shoulder is formed on the outer side of the non-working end of the spindle. One end of the thrust piston abuts against the rear axle shoulder, and the other end of the thrust bearing is pressed and fixed by a piston cap fixed on the non-working end of the spindle.

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