High-precision grinding wheel spindle structure and gantry surface grinding machine thereof

Abstract

The invention relates to the technical field of grinding machines, and discloses a high-precision grinding wheel spindle structure and a gantry surface grinding machine thereof.The high-precision grinding wheel spindle structure comprises a machine shell, a torque motor, a spindle and a grinding wheel, a hydrostatic bearing set is fixed in the machine shell, a dynamic balance device is arranged on the spindle, and a balance adjusting mechanism is installed on the grinding wheel; the balance adjusting mechanism comprises a housing component, a first balance weight, a second balance weight and an adjusting assembly, the housing component is fixed to the outer side of the grinding wheel and divided into a first cavity and a second cavity through a partition plate, the first balance weight and the second balance weight are arranged in the first cavity side by side in the axial direction of the main shaft, and the first balance weight is provided with an outer shaft piece; the second balance weight is provided with an inner shaft piece, a coaxial differential gear structure in transmission connection with the inner shaft piece and the outer shaft piece is arranged in the second cavity, and the adjusting assembly is in transmission connection with the coaxial differential gear structure through a worm and gear structure. On-line balance adjustment of the grinding wheel can be completed, complete non-physical contact between the main shaft and each hydrostatic bearing is achieved, and high-precision machining of the grinding machine is guaranteed.

Description

Technical Field

[0001] This invention relates to the field of grinding technology, and in particular to a high-precision grinding wheel spindle structure and its gantry surface grinder. Background Technology

[0002] Grinding machines employ high-speed spindle drives. To reduce the vibration amplitude of the spindle and grinding wheel and improve the machining accuracy of the grinding machine, existing manufacturers typically use direct-drive electric spindles to drive the grinding wheel. For example, CN214186746U discloses a direct-drive electric spindle, which includes: a torque motor fixedly installed in the headstock housing, and a spindle that is plugged into the torque motor. The spindle is fixedly connected to the grinding wheel, and the torque motor, spindle, and grinding wheel are coaxially coupled. It also includes at least two bearings sleeved at both ends of the spindle. The outer wall of the bearings abuts against the headstock housing. The bearings are hydrostatic bearings. To improve the spindle's balance, dynamic balancing devices are installed at both ends of the spindle. The use of the aforementioned dynamic balancing devices adopts the dynamic balancing method of a high-speed hydrostatic rear-mounted electric spindle disclosed in CN109482911B.

[0003] However, during production and processing, it was found that applying the aforementioned electric spindle with a dynamic balancing device to a grinding machine still has structural shortcomings, thus restricting the demand for higher precision machining. First, as the grinding wheel installed at the end of the spindle for machining, the density and weight of its various regions are difficult to achieve completely uniformity, resulting in a center of gravity shift. The self-balancing device on the spindle cannot be used to balance the center of gravity of the grinding wheel, and the unbalanced grinding wheel will cause a significant reduction in the machining accuracy of the grinding machine. Second, as the hydrostatic bearing used to support the spindle, in order to ensure the sealing of the oil film, its end needs to use a skeleton seal. There is physical contact between the skeleton seal and the spindle. When the spindle is balanced by the dynamic balancing device or when there is an unbalanced state due to the eccentricity of the grinding wheel, the spindle and the skeleton seal will continue to wear, resulting in oil leakage from the seal, and in severe cases, a reduction in the spindle rotation accuracy. Summary of the Invention

[0004] To address the shortcomings of the prior art, this invention provides a high-precision grinding wheel spindle structure and its gantry surface grinder, which can perform online balance adjustment of the grinding wheel and achieve completely non-physical contact between the spindle and each hydrostatic bearing, thereby ensuring high-precision machining of the grinder.

[0005] The technical solution of this invention is as follows: a high-precision grinding wheel spindle structure, comprising a housing, a torque motor fixed inside the housing, a spindle rotating in cooperation with the torque motor, and a grinding wheel fixed at the end of the spindle. Hydrostatic bearing assemblies rotating relative to the spindle are fixed inside the housing on both sides of the torque motor. A dynamic balancing device is provided on the spindle, and a balancing adjustment mechanism is installed on the grinding wheel. The balancing adjustment mechanism includes a cover component, a first balance weight, a second balance weight, and an adjustment assembly. The cover component is fixed to the outside of the grinding wheel and is divided into a first chamber and a second chamber by a partition. The first and second balance weights are arranged side-by-side along the axial direction of the main shaft within the first chamber. The first balance weight has an outer shaft rotatably mounted in the middle of the partition, and the second balance weight has an inner shaft that passes through and rotatably mounts within the inner cavity of the outer shaft. A coaxial differential gear structure, driven by the inner and outer shafts, is located within the second chamber. The adjustment assembly is driven by a worm gear structure and the coaxial differential gear structure, used to drive the first and second balance weights to rotate in the same direction at different speeds at a certain angle before locking. By installing a balance adjustment mechanism on the grinding wheel, without disassembling the grinding wheel, the positions of the first and second balance weights are changed by rotating the adjustment assembly. The two balance weights generate an unbalanced force acting on the grinding wheel, which is used to counteract the center-of-gravity offset of the grinding wheel, thereby achieving online balance adjustment of the grinding wheel and ensuring the machining accuracy of the grinding machine.

[0006] The adjustment assembly includes a first adjustment unit and a second adjustment unit. The first adjustment unit includes a first knob, an adjustment gear one, and an adjustment gear two. The second unit includes a second knob, an adjustment gear three, and an adjustment gear four. The first knob has an outer rotating seat rotatably mounted on the top of the cover frame. The second knob has an inner rotating seat that passes through and rotatably mounted in the inner cavity of the outer knob. The adjustment gear one is fixedly mounted on the outer side of the end of the outer rotating seat that enters the second chamber. The adjustment gear three is fixedly mounted on the outer side of the end of the inner rotating seat that exits the outer rotating seat. The adjustment gear two and the adjustment gear four are interchangeably fitted to the input end of the worm gear structure and mesh with the corresponding adjustment gear one and adjustment gear three, respectively. The transmission ratio between adjustment gear one and adjustment gear two has a multiple relationship with the transmission ratio between adjustment gear three and adjustment gear four.

[0007] The worm gear structure includes a first worm, a second worm, and a first worm wheel. The first worm wheel and the second worm are coaxially fixed and rotatably mounted on the partition plate along an axial direction perpendicular to the main shaft via a bearing seat. The first worm is rotatably mounted on the partition plate along an axial direction parallel to the main shaft and has an assembly shaft that serves as the input end of the worm gear mechanism. The first worm meshes with the first worm wheel for transmission, and the second worm is in transmission engagement with the coaxial differential gear structure.

[0008] The coaxial differential gear structure comprises a first gear, a second worm gear, a second gear meshing with the first gear, and a third worm gear meshing with the second worm gear. The second worm gear is fixedly mounted on the outer side of one end of the outer shaft that penetrates into the second chamber and meshes with the second worm for transmission. The first gear is fixedly mounted on the outer side of one end of the inner shaft that extends out of the outer shaft. The second gear and the third worm gear are coaxially fixed and rotatably mounted on the partition along an axis parallel to the main shaft. The transmission ratio between the second gear and the first gear is different from the transmission ratio between the third worm gear and the second worm gear.

[0009] The hydrostatic bearing assembly includes a front hydrostatic bearing and a rear hydrostatic bearing. The front hydrostatic bearing has a front bearing oil groove facing the main shaft and an axial oil groove facing the shaft shoulder. A first-stage return oil groove is provided between the front sealing oil edge of the front bearing oil groove and the inner sealing oil edge of the axial 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 bearing oil groove in a direction away from the first-stage return oil groove. A primary return oil groove is sequentially provided along the axial oil groove in a direction away from the first-stage return oil groove. The rear hydrostatic bearing has a rear pressure oil groove facing the main shaft and an axial air groove facing the thrust portion of the main shaft. The two sealing edges of the rear pressure oil groove are provided with a set of rear primary oil grooves and a set of rear secondary oil 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 pressure oil groove and a second throttling oil passage for oil entering the axial oil groove. The rear hydrostatic bearing is provided with a third throttling oil passage for oil entering the rear pressure oil groove and a first air intake passage for air entering the axial air groove. The oil film in the front pressure groove on the front hydrostatic bearing and the rear pressure groove on the rear hydrostatic bearing completes the radial balance of the spindle. The oil film pressure in the axial groove on the front hydrostatic bearing and the gas pressure in the axial air groove on the rear hydrostatic bearing complete the axial balance of the spindle. At the same time, the first-stage return oil groove I, the first-stage return oil groove II and the primary return oil groove on the front hydrostatic bearing, and the second-stage return oil groove on the rear hydrostatic bearing ensure the first-stage pressurized return of the oil film in the hydrostatic oil chamber. The first-stage return oil groove and the secondary return oil groove on the front hydrostatic bearing, and the second-stage return oil groove on the rear hydrostatic bearing ensure the overflow return of the oil film after the first-stage pressurized return, forming a sealed return oil effect without the need for a skeleton. This achieves completely non-physical contact between the spindle and each hydrostatic bearing. During the dynamic balancing process of the spindle, there is no wear on the bearings, ensuring that the grinding wheel has sufficiently high machining accuracy while the spindle rotates at high speed.

[0010] The number of the front pressure bearing oil groove, the rear 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 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 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 within the axial oil groove. A small orifice throttling device is installed at the inlet of each of the first, second, and third throttling oil passages.

[0011] 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 outer side. The first oil baffle ring and the primary oil return groove form an annular oil return channel. The secondary oil return groove is located between the first oil baffle ring and the second oil baffle ring.

[0012] The front hydrostatic bearing is provided with a first oil return channel for returning oil to the first-stage oil return groove 1, the first-stage oil return groove 2, and the primary oil return groove. There are several first oil return channels, which are radially distributed in the circumferential direction within the front hydrostatic bearing. The front hydrostatic bearing is also provided with a second oil return channel for returning oil to the first-stage oil return groove 2 and the secondary oil return groove. The inlet of the second oil return channel is located at the lowest position of the first-stage oil return groove 2 and the secondary oil return groove of the assembled front hydrostatic bearing.

[0013] The rear hydrostatic bearing is provided with a third oil return channel for returning oil to the first-stage oil return groove and a fourth oil return channel for returning oil to the second-stage oil return groove. There are several third oil return channels, which are radially distributed in the circumferential direction within the rear hydrostatic bearing. The entrance of the fourth oil return channel is located at the lowest point of the second-stage oil return groove of the assembled rear hydrostatic bearing.

[0014] The present invention also provides a gantry surface grinder, including a bed, an X-axis feed unit, a Y-axis feed unit, a Z-axis feed unit, and the aforementioned high-precision grinding wheel spindle structure. The X-axis feed unit is connected to the bed, the Y-axis feed unit is connected to the X-axis feed unit via hydrostatic guide rails, and the Z-axis feed unit is connected to the Y-axis feed unit via a rolling-sliding composite guide rail. The machine housing is laterally fixed on the free end of the Z-axis feed unit.

[0015] In summary, the present invention has the following main beneficial effects: This invention achieves online balance adjustment of the grinding wheel by installing a balancing mechanism on the grinding wheel. Without disassembling the grinding wheel, rotating the adjustment assembly changes the positions of the first and second balance weights. These two balance weights create an unbalanced force acting on the grinding wheel, which counteracts the wheel's center of gravity shift, thus ensuring the grinding machine's machining accuracy. Improvements are made to the front and rear hydrostatic bearings. The front hydrostatic bearing has a first-stage oil return groove (first stage), a second-stage oil return groove, and a primary oil return groove, while the rear hydrostatic bearing has a second-stage oil return groove. These provide first-stage pressurized oil return to the oil film within the hydrostatic oil chamber. The first-stage and second-stage oil return grooves of the front hydrostatic bearing and the second-stage oil return groove of the rear hydrostatic bearing ensure that the oil film overflows after the first-stage pressurized oil return, creating a sealed oil return effect without the need for a frame. This achieves completely non-physical contact between the spindle and each hydrostatic bearing. During the spindle's dynamic balancing process, the bearings experience no wear, ensuring that the grinding wheel maintains sufficiently high machining accuracy while the spindle rotates at high speed. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the high-precision grinding wheel spindle structure in this invention; Figure 2 This is a cross-sectional schematic diagram of the high-precision grinding wheel spindle structure in this invention; Figure 3 This is a cross-sectional schematic diagram of two chambers in the balance adjustment assembly of the present invention, wherein, Figure 3 (a) is a cross-sectional view of the first chamber. Figure 3 (b) is a cross-sectional view of the second chamber; Figure 4 This is a schematic diagram of the structure of the balance adjustment component after removing the cover component in this invention; Figure 5 This is a schematic diagram of the balance adjustment component from another angle after the cover component is removed; Figure 6 This is a schematic diagram of the front hydrostatic bearing in this invention; Figure 7 This is a front view of the front hydrostatic bearing in this invention; Figure 8 It is along Figure 7 A cross-sectional view along the AA direction; Figure 9 It is along Figure 7 A cross-sectional view along the BB direction; Figure 10 It is along Figure 7 A cross-sectional view along the CC direction; Figure 11 It is along Figure 7 A cross-sectional view along the DD direction; Figure 12This is a schematic diagram of the structure of the rear hydrostatic bearing in this invention; Figure 13 This is a front view of the rear hydrostatic bearing in this invention; Figure 14 It is along Figure 13 Sectional view along the EE direction; Figure 15 It is along Figure 13 A cross-sectional view along the FF direction; Figure 16 It is along Figure 13 A cross-sectional view along the GG direction; Figure 17 It is along Figure 2 A cross-sectional view along the HH direction; Figure 18 It is along Figure 2 Sectional view along direction II; Figure 19 This is a schematic diagram of the gantry surface grinder in this invention.

[0017] Reference numerals: 100, main shaft; 101, shoulder; 102, thrust piston; 200, grinding wheel; 300, balance adjustment mechanism; 301, casing component; 3011, casing cylinder; 3012, casing cover plate; 3012, partition plate; 3013, intermediate plate; 302, first counterweight; 3021, outer shaft; 303, second counterweight; 3031, inner shaft; 3032, ball bearing; 304, coaxial differential gear structure; 3041, second worm gear; 3042, first gear; 3043, third worm gear; 3044, second gear; 3045, first rotating shaft; 305, worm gear structure; 3051, first worm; 3052, assembly shaft; 3053, first worm gear; 3054 3055. Second worm gear; 306. Bearing housing; 306. Adjusting assembly; 3061. First knob; 3062. Outer rotating seat; 3063. Adjusting gear one; 3064. Adjusting gear two; 3065. Second knob; 3066. Inner rotating seat; 30661. Connecting end; 3067. Adjusting gear three; 3068. Adjusting gear four; 3069. Transmission gear; 307. Second rotating shaft; 400. Front hydrostatic bearing; 401. Front pressure oil groove; 402. Axial oil groove; 403. First stage return oil groove one; 404. First stage return oil groove two; 405. First stage return oil groove; 406. Primary return oil groove; 407. Secondary return oil groove; 408. First throttling oil passage; 409. Second throttling oil passage; 410. First return... Oil passages; 410a, First return oil passage a; 410b, First return oil passage b; 410c, First return oil passage c; 411, Second return oil passage; 411a, Second return oil passage a; 411b, Second return oil passage b; 411c, Second return oil connecting branch; 412, First oil baffle ring; 413, Second oil baffle ring; 414, Air seal groove; 415, Second air intake passage; 416, Front annular oil inlet groove; 500, Rear hydrostatic bearing; 501, Rear pressure bearing oil groove; 502, Axial air groove; 503, Rear primary return oil groove; 504, Rear secondary return oil groove; 505, Third throttling oil passage; 506, First air intake passage; 507, Third return oil passage; 5071, Primary oil groove; 508, Fourth return oil passage; 5081, Secondary oil groove 509. Annular air inlet groove; 600. Housing; 601. Hydrostatic bearing seat; 6011. Rear oil inlet channel; 6012. Rear annular oil inlet groove; 6013. Fifth oil return channel; 6014. Sixth oil return channel; 6015. Rear primary oil collection groove; 6016. Rear secondary oil collection groove; 602. Forward oil channel; 603. Rear oil inlet channel; 604. Air supply channel; 605. Air source connector; 606. First primary oil return channel; 6061. First primary oil collection groove; 607. First secondary oil return channel; 6071. First secondary oil collection groove; 608. Rear primary oil return channel; 609. Rear secondary oil return channel; 700. Torque motor; 701. Stator; 702. Rotor; 800. Dynamic balancing device; 801. Threaded hole;802. Dynamic balancing head; 803. Transmission line; 804. Receiver; 805. Transmitter; 900. Airtight cover; 901. Annular air chamber; 1. Bed; 2. Worktable; 3. Double column crossbeam; 4. Transverse slide; 5. Vertical slide; 6. Hydrostatic guide rail. Detailed Implementation

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

[0019] Hereinafter, 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 technical features indicated. Thus, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0020] Furthermore, in this invention, 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 2As shown, this invention provides a high-precision grinding wheel spindle structure, including a housing 600, a torque motor 700 fixed inside the housing 600, a spindle 100 rotating in cooperation with the torque motor 700, and a grinding wheel 200 fixed at the end of the spindle 100. Hydrostatic bearing assemblies rotating relative to the spindle 100 are fixed inside the housing 600 on both sides of the torque motor 700. Specifically, the stator 701 of the torque motor 700 is fixed in the middle of the inner cavity of the housing 600, and the rotor 702 of the torque motor 700 is fixed in the middle of the spindle 100. The fixed magnetic field of the stator 701 interacts with the current of the rotor 702 to generate torque. A shoulder 101 is formed on the outer side of the working end of the spindle 100, and a shoulder 101 is fixed on the outer side of its non-working end. A thrust piston 102; wherein, the spindle 100 is also provided with a dynamic balancing device 800, which adopts a structure similar to the dynamic balancing structure disclosed in CN109482911B, namely, the first set of dynamic balancing structures includes a threaded hole 801 located on the non-working end face of the spindle 100; the second set of dynamic balancing structures includes a threaded hole 801 on the outer end face of the shoulder 101 of the spindle 100 and a threaded hole 801 on the outer end face of the thrust piston 102; the third set of dynamic balancing structures includes a dynamic balancing head 802 in the inner hole of the spindle 100, a transmission line 803 and a receiver 804 connected to the non-working end of the spindle 100, a transmitter 805 fixedly connected to the rear end of the housing 600, and a vibration sensor on the housing 600.

[0022] like Figure 1 As shown, a balance adjustment mechanism 300 is installed on the grinding wheel 200. The balance adjustment mechanism 300 includes a housing component 301, a first balance weight 302, a second balance weight 303, and an adjustment assembly 306. The housing component includes a housing cylinder 3011 and a housing cover plate 3012. A flange is formed on one side of the housing cylinder 3011, which is coaxially fixed to the outer surface of the grinding wheel 200 facing away from the spindle 100 by bolts. The housing cover plate 3012 is fixed to the other side of the housing cylinder 3011, forming a chamber with the housing cylinder 3011. A partition plate 3012 is fixed inside the housing cover plate, dividing the chamber into a first chamber closer to the grinding wheel 200 and a second chamber farther from the grinding wheel 200. Figure 3As shown in (a), the first counterweight 302 and the second counterweight 303 are arranged side by side in the first chamber along the axial direction of the main shaft 100. The first counterweight 302 has an outer shaft 3021 rotatably disposed in the middle of the partition plate 3012, and the second counterweight 303 has an inner shaft 3031 that penetrates and rotatably disposed in the inner cavity of the outer shaft 3021. Preferably, in order to ensure the stability of the rotation of the first counterweight 302 and the second counterweight 303, an intermediate plate 3013 is integrally formed inside the cover cylinder 3011. The intermediate plate 3013, the inner wall of the cover cylinder 3011, and the partition plate 3012 together form the first chamber. The first end of the outer shaft 3021 is assembled on the partition plate 3012 via a bearing, and the first end of the inner shaft 3031 is assembled on the intermediate plate 3013 via a bearing. The second end of the inner shaft 3031 is connected to the outer shaft 3021 via a bearing. The second end of the shaft 3021 passes through and exits the first end of the outer shaft 3021. The second chamber is provided with a coaxial differential gear structure 304 that is driven by the second end of the inner shaft 3031 and the first end of the outer shaft 3021. The adjustment component 306 is driven by the worm gear structure 305 and the coaxial differential gear structure 304 to drive the first balance hammer 302 and the second balance hammer 303 to rotate in the same direction but at different speeds at a certain angle and then lock. Thus, through the above-mentioned balance adjustment mechanism 300, the positions of the first balance hammer 302 and the second balance hammer 303 can be changed without disassembling the grinding wheel 200. The two balance hammers form an unbalanced force acting on the grinding wheel 200. This unbalanced force is used to offset the center of gravity offset of the grinding wheel 200, thereby realizing the online balance adjustment of the grinding wheel 200 and ensuring the machining accuracy of the grinding machine.

[0023] Specifically, the first counterweight 302 and the second counterweight 303 are semi-circular structures with the same structure. The center of the first counterweight 302 has an assembly protrusion for connecting the second end of the outer shaft 3021, and the center of the second counterweight 303 has an assembly protrusion for connecting the inner shaft 3031 located between the second end of the outer shaft 3021 and the intermediate plate 3013. All of the above connections are fixedly assembled by key fitting.

[0024] Further preferably, to improve the efficiency and accuracy of the grinding wheel 200 during balancing, the adjusting assembly 306 includes a first adjusting unit and a second adjusting unit. The first adjusting unit includes a first knob 3061, an adjusting gear one 3063, and an adjusting gear two 3064. The second unit includes a second knob 3065, an adjusting gear three 3067, and an adjusting gear four 3068. Figure 3As shown in (b), the first knob 3061 has an outer rotating seat 3062 rotatably disposed in the middle of the cover plate 3012, and the second knob 3065 has an inner rotating seat 3066 that penetrates and rotatably disposed in the inner cavity of the outer knob. Specifically, the first end of the outer rotating seat 3062 is fixedly connected to the first knob 3061, the middle part of the outer rotating seat 3062 is rotatably mounted on the cover plate 3012 via a bearing, the second end of the outer rotating seat 3062 is located in the second cavity, and the first end of the inner rotating seat 3066 is fixedly connected to the second knob 3065. The end of the outer rotating seat 3062 passes through the first end (the middle of the first knob 3061) and exits through the second end of the outer rotating seat 3062 to form a mating end 30661. This mating end 30661 is coaxially mated with the second end of the inner shaft 3031. Specifically, a ball bearing 3032 is embedded in the end face of the second end of the inner shaft 3031, and the mating end 30661 is sealed with the inner ring of the ball bearing 3032, thereby achieving stable rotation of the inner rotating seat 3066. The adjusting gear 3063 is fixedly assembled on the second end of the outer rotating seat 3062. Above, adjusting gear three 3067 is fixedly mounted on the second end of the inner rotating seat 3066. Adjusting gear two 3064 and adjusting gear four 3068 are mounted on the input end of the worm gear structure 305 and mesh with the corresponding adjusting gear one 3063 and adjusting gear three 3067, respectively. The transmission ratio between adjusting gear one 3063 and adjusting gear two 3064 is a multiple of the transmission ratio between adjusting gear three 3067 and adjusting gear four 3068, thereby dividing the first adjusting unit and the second adjusting unit into coarse adjusting units based on the magnitude of this transmission ratio. The system includes a fine-tuning unit, where a small-ratio adjustment unit coarsely adjusts the positions of the first balance weight 302 and the second balance weight 303 using a corresponding knob, and a large-ratio adjustment unit finely adjusts the positions of the first balance weight 302 and the second balance weight 303 using a corresponding knob. Preferably, in this scheme, the first adjustment unit is a coarse-tuning unit and the second adjustment unit is a fine-tuning unit. Specifically, the transmission ratio between the third adjustment gear 3067 and the fourth adjustment gear 3068 is twice the transmission ratio between the first adjustment gear 3063 and the second adjustment gear 3064.

[0025] Further preferably, a transmission gear 3069 may be provided in the second chamber. The transmission gear 3069 is fixed on the second rotating shaft 307 by key engagement. The two ends of the second rotating shaft 307 are rotatably connected to the partition plate 3012 and the cover plate 3012, respectively. The transmission gear 3069 is located between the first adjusting gear 3063 and the second adjusting gear 3064. The first adjusting gear 3063 is engaged with the second adjusting gear 3064 via the transmission gear 3069, so that the adjustment directions of the first adjusting unit and the second adjusting unit are opposite.

[0026] like Figure 4 and Figure 5As shown, the worm gear structure 305 includes a first worm 3051, a second worm 3054, and a first worm wheel 3053. The first worm wheel 3053 and the second worm 3054 are coaxially fixed and rotatably mounted on a partition plate 3012 via a bearing seat 3055 along an axial direction perpendicular to the main shaft 100. The first worm 3051 is rotatably mounted on the partition plate 3012 along an axial direction parallel to the main shaft 100 and has an assembly shaft 3052 serving as the input end of the worm gear mechanism. Preferably, the end of this assembly shaft is rotatably connected to the cover plate 3012. Adjusting gears 3064 and 3068 are both fixedly mounted on the assembly shaft 3052 by key engagement and rotate coaxially with the first worm 3051. The first worm 3051 meshes with the first worm wheel 3053 to form a transmission mechanism. At the first worm gear engagement point, the second worm 3054 engages with the coaxial differential gear structure 304 to form the second worm gear engagement point. In this design, the lead angle of the first worm 3051 is less than the equivalent friction angle between the meshing teeth of the first worm gear 3053, thus creating a self-locking relationship between the first worm 3051 and the first worm gear 3053. Similarly, the lead angle of the second worm 3054 is less than the equivalent friction angle between the meshing teeth of the worm gears in the coaxial differential gear structure 304, also creating a self-locking relationship between the second worm 3054 and the coaxial differential gear structure 304. The dual self-locking force generated by the double worm gear structure 305 ensures that the two counterweights remain more stable in their balanced positions, unaffected by the rotation of the main shaft 100 during its rotation.

[0027] Specifically, the coaxial differential gear structure 304 includes a first gear 3042, a second worm gear 3041, a second gear 3044 meshing with the first gear 3042, and a third worm gear 3043 meshing with the second worm gear 3041. The second worm gear 3041 is fixedly mounted on the first end of the outer shaft 3021 and meshes with the second worm 3054 for transmission. The first gear 3042 is fixedly mounted on the second end of the inner shaft 3031. Figure 5 As shown, the second gear 3044 and the third worm gear 3043 are coaxially fixed and rotatably mounted on the partition plate 3012 along an axis parallel to the main shaft 100. Specifically, the second gear 3044 and the third worm gear are fixed on the first rotating shaft 3045 by keying. The two ends of the first rotating shaft 3045 are rotatably connected to the partition plate 3012 and the cover plate 3012, respectively. In order to make the inner shaft 3031 and the outer shaft 3021 have different rotational speeds, the transmission ratio between the second gear 3044 and the first gear 3042 and the transmission ratio between the third worm gear 3043 and the second worm gear 3041 are different.

[0028] like Figure 2 As shown, the hydrostatic bearing assembly includes a front hydrostatic bearing 400 and a rear hydrostatic bearing 500, as... Figure 6As shown, the front hydrostatic bearing 400 has a front pressure-bearing oil groove 401 facing the main shaft 100 and an axial oil groove 402 facing the shoulder portion 101 of the main shaft 100, as... Figure 8 As shown, a first-stage return oil groove 403 is provided between the front sealing oil edge of the front pressure-bearing oil groove 401 and the inner sealing oil edge of the axial oil groove 402. A second-stage return oil groove 404 and a third-stage return oil groove 405 are sequentially provided on the rear sealing oil edge of the front pressure-bearing oil groove 401 along a direction away from the first-stage return oil groove 403. A primary return oil groove 406 and a secondary return oil groove 407 are sequentially provided on the axial oil groove 402 along a direction away from the first-stage return oil groove 403. Figure 12 As shown, the rear hydrostatic bearing 500 has a rear pressure-bearing oil groove 501 facing the main shaft 100 and an axial air groove 502 facing the thrust portion of the main shaft 100, as... Figure 14 As shown, the two sealing edges of the rear pressure oil groove 501 are sequentially provided with a set of rear primary oil return grooves 503 and a set of rear secondary oil return grooves 504 in the direction away from the center. Figure 8 and Figure 9 As shown, the front hydrostatic bearing 400 is provided with a first throttling oil passage 408 for oil inlet to the front pressure oil groove 401 and a second throttling oil passage 409 for oil inlet to the axial oil groove 402, as follows. Figure 14 As shown, the rear hydrostatic bearing 500 is provided with a third throttling oil passage 505 for oil to enter the rear pressure oil groove 501 and a first air intake passage 506 for air to enter the axial air groove 502. By setting the front pressure oil groove 401 and axial oil groove 402 on the front hydrostatic bearing 400, and setting the rear pressure oil groove 501 and axial air groove 502 on the rear hydrostatic bearing 500, the spindle 100 is radially floating between the oil films and axially balanced between the air pressure and oil pressure, thereby realizing the support action of the hydrostatic bearing. At the same time, the first-stage return oil groove 403, the second-stage return oil groove 404 and the primary return oil groove 405 located in the front hydrostatic bearing 400 are also provided with the third throttling oil passage 505 for oil to enter the rear pressure oil groove 501 and axial air groove 502. 06. The first-stage oil return groove 503 located in the rear hydrostatic bearing 500 ensures the first-stage pressurized oil return to the oil film in the hydrostatic oil chamber. The first-stage oil return groove 405 and the second-stage oil return groove 407 located in the front hydrostatic bearing 400, and the second-stage oil return groove 504 located in the rear hydrostatic bearing 500 ensure the overflow oil return after the first-stage pressurized oil return, forming a sealed oil return effect without the need for a skeleton. This achieves completely non-physical contact between the spindle 100 and each hydrostatic bearing. During the dynamic balancing process of the spindle 100, the bearings do not wear, thus ensuring that the grinding wheel 200 has sufficiently high machining accuracy while the spindle 100 rotates at high speed.

[0029] The number of the front pressure-bearing oil groove 401, the rear pressure-bearing oil groove 501, the first throttling oil passage 408, the second throttling oil passage 409, and the third throttling oil passage 505 is at least two. Specifically, in this solution, for example... Figure 7As shown, there are four front pressure-bearing oil grooves 401 and four first throttling oil passages 408. Each front pressure-bearing oil groove 401 is circumferentially spaced inside the front hydrostatic bearing 400 and corresponds one-to-one with the outlet of each first throttling oil passage 408. Figure 13 As shown, there are four rear pressure-bearing oil grooves 501 and three throttling oil passages 505. Each rear pressure-bearing oil groove 501 is circumferentially spaced inside the rear hydrostatic bearing 500 and corresponds one-to-one with the outlet of each third throttling oil passage 505. Figure 7 As shown, there are three second throttling oil passages 409. The outlets of each second throttling oil passage 409 are distributed circumferentially within the axial oil groove 402. 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 408, each second throttling oil passage 409, and each third throttling oil passage 505. Through the small-hole throttler, the hydraulic resistance of any throttling oil passage and the hydraulic resistance of the corresponding oil film in the oil groove form a series hydraulic circuit. For example, when radially stressed, the sealing edge of the front pressure-bearing oil groove 401 / rear pressure-bearing oil groove 501 facing the stressed side... As the gap between the main shaft 100 and the spindle decreases, the hydraulic resistance of the internal oil film increases. Consequently, the hydraulic resistance of the orifice throttle at the inlet of the first throttling oil passage 408 / third throttling oil passage 505 decreases, thereby increasing the amount of oil entering the corresponding front pressure oil groove 401 / rear pressure oil groove 501 to balance the radial force. Similarly, when subjected to axial force, the gap between the sealing edge of the axial oil groove 402 and the shoulder 101 decreases, the hydraulic resistance of the internal oil film increases, the hydraulic resistance of the orifice throttle at the inlet of the second throttling oil passage 409 decreases, and the amount of oil entering the axial oil groove 402 increases to balance the axial force.

[0030] Further preferred, such as Figure 9 As shown, the primary oil return groove 406 is radially arranged outside the axial oil groove 402. The front hydrostatic bearing 400 outside the primary oil return groove 406 is sequentially formed with a first oil baffle ring 412 and a second oil baffle ring 413 along the axial direction. The first oil baffle ring 412 and the primary oil return groove 406 form an annular oil return channel, thereby increasing the amount of pressurized oil flowing from the axial oil groove to the primary oil return groove 406. Correspondingly, the secondary oil return groove 407 is located between the first oil baffle ring 412 and the second oil baffle ring 413.

[0031] like Figure 10 and Figure 11As shown, the front hydrostatic bearing 400 is provided with a first oil return channel 410 for returning oil to the first-stage oil return groove 403, the second-stage oil return groove 404 and the primary oil return groove 406, and a second oil return channel 411 for returning oil to the second-stage oil return groove 405 and the secondary oil return groove 407. Specifically, the first oil return channel 410 includes a first oil return channel b 410b with its inlet located in the second-stage oil return groove 404 and radially penetrating the front hydrostatic bearing 400, and a first oil return channel c 410c with its inlet located in the primary oil return groove 406 and axially penetrating the front hydrostatic bearing 400. The inlet is located within the first-stage return oil groove 403 and extends obliquely backward into the first return oil c channel 410c, the first return oil a channel 410a. All three converge at the through-hole of the first return oil b channel 410b on the surface of the front hydrostatic bearing 400. The through-hole formed at the rear end of the first return oil c channel 410cc is sealed by an oil plug. The aforementioned second return oil channel 411 includes the second return oil a channel 411a with its inlet located within the first-stage return oil groove 405 and the second return oil b channel 411b with its inlet located within the secondary return oil groove 407. Similarly, as... Figure 15 and Figure 16 As shown, the rear hydrostatic bearing 500 is provided with a third oil return channel 507 for returning oil to the rear first-stage oil return groove 503 and a fourth oil return channel 508 for returning oil to the rear second-stage oil return groove 504.

[0032] Further preferred, in order to improve the oil return sealing effect, such as Figure 7 and Figure 13 As shown, there are several first oil return channels 410, radially distributed circumferentially within the front hydrostatic bearing 400, and several third oil return channels 507, radially distributed circumferentially within the rear hydrostatic bearing 500, to provide circumferential return of pressurized oil flowing out from the sealing edge of the oil film in the axial oil groove 402, the front pressure oil groove 401, and the rear pressure oil groove 501. After circumferential return through the first oil return channels 410 and the third oil return channels 507, the oil overflowing from the first-stage oil return groove 404 enters the first-stage oil return groove 405, and the oil overflowing from the primary oil return groove 406 enters the secondary oil return groove 407. The aforementioned oil, without oil pressure, will accumulate in the corresponding oil grooves. Therefore, the inlet position of the second oil return channel a 411a is set at the lowest position of the front secondary oil return groove 405 of the assembled front hydrostatic bearing 400, and the inlet position of the second oil return channel b 411b is set at the lowest position of the secondary oil return groove 407. Similarly, the inlet position of the fourth oil return channel 508 is set around the lowest point of the rear secondary oil return groove 504204 of the assembled rear hydrostatic bearing 500. More preferably, there are two of the above-mentioned second oil return channels a 411a, second oil return channels b 411b, and fourth oil return channels 508, which are symmetrically arranged on both sides of their respective lowest points to increase the maximum oil return volume by gravity.

[0033] Because the grinding wheel 200 mounted on the working end of the spindle 100 produces metal shavings during grinding, in order to prevent these shavings from entering the oil return groove and affecting the normal operation of the spindle 100, such as... Figure 8 As shown, the second oil baffle ring 413 has an air seal groove 414 in the middle. Preferably, an air seal cover 900 is fixed on the outer side of the front end of the front static pressure bearing 400. The air seal cover 900 and the front static pressure bearing 400 enclose an annular air chamber 901. The air inlet connector 605 on the outer side of the annular air chamber 901 is connected to an external air source, and the inner side is connected to the air seal groove 414 through the second air inlet channel 415. More preferably, there are several second air inlet channels 415, which are radially distributed in the circumferential direction on the front static pressure bearing 400 corresponding to the annular air chamber 901, so that the gas enters the air seal groove 414 evenly to form an air curtain and block flying debris.

[0034] like Figure 1 and Figure 2 As shown, since the front hydrostatic bearing 400 and the rear hydrostatic bearing 500 are respectively fixed at both ends of the housing 600, in order to ensure effective communication between the oil circuit and the outside world, the housing 600 has a forward oil passage 602 connected to the first throttling oil passage 408 and the second throttling oil passage 409, a rear oil passage 603 connected to the third throttling oil passage, an air supply passage 604 connected to the first air intake passage 506, a first-stage return oil passage 606 connected to the first return oil passage 410, a first-stage return oil passage 607 connected to the second return oil passage 411, a rear-stage return oil passage 608 connected to the third return oil passage 507, and a rear-stage return oil passage 609 connected to the fourth return oil passage 508.

[0035] Further preferably, to facilitate the installation of the rear hydrostatic bearing 500, a hydrostatic bearing housing 601 is sealed and fixed to the outside of the rear hydrostatic bearing 500, and is fixedly connected to the rear end of the housing 600 via the hydrostatic bearing housing 601. Specifically, as shown... Figure 2 As shown, the surface of the hydrostatic bearing housing 601 is provided with a rear annular oil inlet groove 6012. The rear annular oil inlet groove 6012 is connected to each of the third throttling oil passages 505 via multiple rear oil supply channels 6011. The inner wall of the housing 600 and the rear annular oil inlet groove 6012 together form a rear annular oil inlet channel connected to the rear oil inlet channel 603. Figure 8 As shown, the front hydrostatic bearing 400 has a front annular oil inlet groove 416 on its surface. The inlets of the first throttling oil passage 408 and the second throttling oil passage 409 are located inside the front annular oil inlet groove 416. The inner wall of the housing 600 and the front annular oil inlet groove 416 together form a front annular oil inlet channel connected to the forward oil passage 602. Of course, in order to ensure that the air pressure in the axial air groove 502 is applied evenly, such as... Figure 12 and Figure 13As shown, there are several first air intake channels 506, which are radially distributed along the circumference at the rear end of the rear hydrostatic bearing 500. An annular air intake groove 509 is provided on the outer side of the rear end of the rear hydrostatic bearing 500. The inlet of each first air intake channel 506 is located on the annular air intake groove 509. The inner wall of the hydrostatic bearing seat 601 and the annular air intake groove 509 together form an annular air passage connected to the air supply channel 604.

[0036] Further preferred, such as Figure 12 , Figure 15 and Figure 16 As shown, the surface of the rear hydrostatic bearing 500 is provided with a primary oil groove 5071 for connecting two corresponding third oil passages 507 on two rear primary oil return grooves 503, and a secondary oil groove 5081 for connecting two corresponding fourth oil passages 508 on two rear secondary oil return grooves 504, as shown. Figure 18 As shown, the hydrostatic bearing housing 601 is provided with a fifth oil return channel 6013 for connecting the primary oil tank 5071 and the subsequent primary oil return channel 608, and a sixth oil return channel 6014 for connecting the secondary oil tank 5081 and the subsequent secondary oil return channel 609. Specifically, since there are several third oil return channels 507, there are also several corresponding primary oil tanks 5071 and fifth oil return channels 6013. In order to facilitate the centralized collection of pressurized oil from each fifth oil return channel 6013 into the subsequent primary oil return channel 608, the surface of the hydrostatic bearing housing 601 is provided with a subsequent primary oil return channel 608. The oil collecting trough 6015, which is sealed together with the housing 600 to form a rear arc-shaped oil collecting cavity connected to the subsequent primary oil return channel 608, has its outlet located within the subsequent primary oil collecting trough 6015. A subsequent secondary oil collecting trough 6016 is provided at the corresponding positions of the hydrostatic bearing seat 601 and the sixth oil return channel 6014. The subsequent secondary oil return channel 609 is horizontally positioned at the bottom of the housing 600 to accommodate the gravity return of oil from the fourth oil return channel 508 to the secondary oil trough 5081, the sixth oil return channel 6014, and the subsequent secondary oil collecting trough 6016. Similarly, as... Figure 17 As shown, in order to collect and recover the pressurized oil from each of the first return oil passages 410 into the preceding stage return oil passage 606, a preceding stage oil collecting groove 6061 is provided on the inner side of the housing 600. This groove, together with the front hydrostatic bearing 400, forms a front arc-shaped oil collecting chamber connected to the preceding stage return oil passage 606. The outlets of each of the first return oil passages 410 are located within this front arc-shaped oil collecting chamber. Figure 2 and Figure 17 As shown, the inner side of the housing 600 is provided with a front secondary oil collecting groove 6071 corresponding to the outlet position of the second oil return channel a 411a, and a second oil return connecting branch 411c is provided along the axial direction to connect the front secondary oil collecting groove 6071 and the second oil return channel b 411b. The front secondary oil return channel 607 is horizontally arranged at the bottom of the housing 600 to accommodate the gravity oil return of the second oil return channel 411-front secondary oil collecting groove 6071.

[0037] The following describes the balance adjustment of the grinding wheel 200. In this scheme, the number of teeth of adjusting gear 1 3063 is 21, the number of teeth of transmission gear 3069 is 26, the number of teeth of adjusting gear 2 3064 is 21, the first worm 3051 has 5 heads, the number of teeth of the first worm wheel 3053 is 16, the second worm 3054 is single-headed, the number of teeth of the second worm wheel 3041 is 20, the number of teeth of the third worm wheel 3043 is 16, the number of teeth of the second gear 3044 is 17, and the number of teeth of the first gear 3042 is 19. Therefore, the transmission ratio between the first knob 3061 and the first counterweight 302 is calculated as follows: The transmission ratio between the first knob 3061 and the second counterweight 303 is: The number of teeth on adjusting gear 3067 is 16, and the number of teeth on adjusting gear 4 is 32. Therefore, the transmission ratio between the second knob 3065 and the first counterweight 302 is calculated as follows: The transmission ratio between the second knob 3065 and the second counterweight 303 is: That is, rotating the first knob 3061 one revolution causes the first counterweight 302 to rotate 1 / 64 revolution and the second counterweight 303 to rotate 1 / 57.22 revolution. Rotating the second knob 3065 one revolution causes the first counterweight 302 to rotate 1 / 128 revolution and the second counterweight 303 to rotate 1 / 114.44 revolution. Therefore, the first knob 3061 drives the first counterweight 302 and the second counterweight 303 to perform coarse adjustments in the same direction but at different speeds. The second knob 3065 drives the first counterweight 302 to rotate 1 / 64 revolution and the second counterweight 303 to rotate 1 / 57.22 revolution. Hammer 302 and the second balancing hammer 303 are fine-tuned in the same direction but at different speeds. When balancing the grinding wheel 200, there is no need to disassemble the grinding wheel 200. After rotating the first knob 3061 online a certain number of times, the grinding wheel 200 is manually rotated. The stationary state of the grinding wheel 200 at any position is observed. Then, the second knob 3065 is rotated. When the grinding wheel 200 can remain stationary at any position, the static balance adjustment is completed, ensuring the dynamic balance properties of the entire assembly spindle 100.

[0038] The return oil routes of the front hydrostatic bearing 400 and the rear hydrostatic bearing 500 are described in detail below. The return oil route of the front hydrostatic bearing 400 is as follows: Hydraulic oil in each of the front pressure oil grooves 401 enters the first-stage return oil groove 404 via the rear sealing edge on one side, and enters the first-stage return oil groove 403 via the front sealing edge and the return oil generated by the axial oil groove 402 via the inner sealing edge on the other side. The return oil generated by the axial oil groove 402 via the outer sealing edge enters the primary return oil groove 406. The three flows converge into the first return oil channels 410 and into the preceding stage oil collection tank 6061, and is discharged through the preceding stage return oil channel 606; the oil overflowing from the preceding stage return oil tank 404 enters the preceding stage return oil tank 405, and the oil overflowing from the annular return oil channel of the primary return oil tank 406 enters the secondary return oil tank 407. Under the action of gravity, both flow into the preceding stage oil collection tank 6071 and are discharged through the preceding stage return oil channel 607; then the static... The return oil route of the pressure bearing 500: the hydraulic oil in each of the rear pressure oil grooves 501 enters the rear first-stage return oil groove 503 through the sealing oil edge, then flows into the first-stage oil groove 5071 through the third return oil channel 507, and then flows into the rear first-stage collection oil groove 6015 through the fifth return oil channel 6013, and is discharged through the rear first-stage return oil channel 608; the oil overflowing from the rear first-stage return oil groove 503 enters the rear second-stage return oil groove 504, and under the action of gravity, flows sequentially through the fourth return oil channel 508. 08. The secondary oil groove 5081 and the sixth return oil channel 6014 converge into the secondary oil collection groove 6016 and are discharged through the secondary return oil channel 609. By designing the double return oil design routes on both sides of each pressure oil groove and axial oil groove 402, the non-contact seal between the hydrostatic bearing and the spindle 100 is ensured. Thus, during the dynamic balancing process of the spindle 100, the bearing does not wear, ensuring that the grinding wheel 200 has sufficiently high machining accuracy while the spindle 100 rotates at high speed.

[0039] like Figure 19As shown, the present invention also provides a gantry surface grinder, including a bed 1, an X-axis feed unit, a Y-axis feed unit, a Z-axis feed unit, and the aforementioned high-precision grinding wheel spindle structure. The X-axis feed unit is connected to the bed 1, the Y-axis feed unit is connected to the X-axis feed unit via hydrostatic guide rails 6, and the Z-axis feed unit is connected to the Y-axis feed unit via a rolling-sliding composite guide rail. The machine housing 600 is laterally fixed on the free end of the Z-axis feed unit. Specifically, in this solution, the X-axis feed unit includes a worktable 2, a double-column crossbeam 3, and a linear motor. The worktable 2 is slidably connected to the upper surface of the bed 1 via the hydrostatic guide rails 6, and the double-column crossbeam 3 is fixed above the worktable 2. Linear motor 1, in conjunction with a grating ruler, drives the worktable 2 to feed precisely along the longitudinal direction (X-axis); the Y-axis feed unit includes a transverse slide 4 and a linear motor 2. The transverse slide 4 is slidably connected to the side of the double-column crossbeam 3 via a hydrostatic guide rail 6. The linear motor 2, in conjunction with a grating ruler, drives the transverse slide 4 to feed precisely along the transverse direction (Y-axis); the Z-axis feed unit includes a vertical slide 5 and a servo motor. The vertical slide 5 is slidably connected to the side of the transverse slide 4 via a roller-sliding composite guide rail. The servo motor drives the ball screw to rotate via a reducer, thereby driving the vertical slide 5 to move along the vertical direction (Z-axis). The lower end of the vertical slide 5 forms the free end of the Z-axis feed unit. The three-axis drive system drives the grinding wheel spindle structure to move, achieving high-precision machining.

[0040] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A high-precision grinding wheel spindle structure, comprising a housing, a torque motor fixed within the housing, a spindle rotating in conjunction with the torque motor, and a grinding wheel fixed at the end of the spindle, wherein hydrostatic bearing assemblies rotating relative to the spindle are fixed within the housing on both sides of the torque motor, and a dynamic balancing device is provided on the spindle, characterized in that, The grinding wheel is equipped with a balancing mechanism, which includes a housing component, a first balancing hammer, a second balancing hammer, and an adjusting assembly. The housing component is fixed to the outside of the grinding wheel and is divided into a first chamber and a second chamber by a partition. The first balancing hammer and the second balancing hammer are arranged side by side along the axial direction of the main shaft in the first chamber. The first balancing hammer has an outer shaft component that is rotatably disposed in the middle of the partition. The second balancing hammer has an inner shaft component that passes through and is rotatably disposed in the inner cavity of the outer shaft component. The second chamber is provided with a coaxial differential gear structure that is drivenly connected to the inner shaft component and the outer shaft component. The adjusting assembly is drivenly connected to the coaxial differential gear structure via a worm gear structure to drive the first balancing hammer and the second balancing hammer to rotate in the same direction but at different speeds at a certain angle and then lock them.

2. The high-precision grinding wheel spindle structure according to claim 1, characterized in that, The adjustment assembly includes a first adjustment unit and a second adjustment unit. The first adjustment unit includes a first knob, an adjustment gear one, and an adjustment gear two. The second unit includes a second knob, an adjustment gear three, and an adjustment gear four. The first knob has an outer rotating seat rotatably mounted on the top of the cover frame. The second knob has an inner rotating seat that passes through and rotatably mounted in the inner cavity of the outer knob. The adjustment gear one is fixedly mounted on the outer side of the end of the outer rotating seat that enters the second chamber. The adjustment gear three is fixedly mounted on the outer side of the end of the inner rotating seat that exits the outer rotating seat. The adjustment gear two and the adjustment gear four are interchangeably fitted to the input end of the worm gear structure and mesh with the corresponding adjustment gear one and adjustment gear three, respectively. The transmission ratio between adjustment gear one and adjustment gear two has a multiple relationship with the transmission ratio between adjustment gear three and adjustment gear four.

3. The high-precision grinding wheel spindle structure according to claim 2, characterized in that, The worm gear structure includes a first worm, a second worm, and a first worm wheel. The first worm wheel and the second worm are coaxially fixed and rotatably mounted on the partition plate along an axial direction perpendicular to the main shaft via a bearing seat. The first worm is rotatably mounted on the partition plate along an axial direction parallel to the main shaft and has an assembly shaft that serves as the input end of the worm gear mechanism. The first worm meshes with the first worm wheel for transmission, and the second worm is in transmission engagement with the coaxial differential gear structure.

4. The high-precision grinding wheel spindle structure according to claim 3, characterized in that, The coaxial differential gear structure comprises a first gear, a second worm gear, a second gear meshing with the first gear, and a third worm gear meshing with the second worm gear. The second worm gear is fixedly mounted on the outer side of one end of the outer shaft that penetrates into the second chamber and meshes with the second worm for transmission. The first gear is fixedly mounted on the outer side of one end of the inner shaft that extends out of the outer shaft. The second gear and the third worm gear are coaxially fixed and rotatably mounted on the partition along an axis parallel to the main shaft. The transmission ratio between the second gear and the first gear is different from the transmission ratio between the third worm gear and the second worm gear.

5. A high-precision grinding wheel spindle structure according to any one of claims 1-4, characterized in that, The hydrostatic bearing assembly includes a front hydrostatic bearing and a rear hydrostatic bearing. The front hydrostatic bearing has a front bearing oil groove facing the main shaft and an axial oil groove facing the shaft shoulder. A first-stage return oil groove is provided between the front sealing oil edge of the front bearing oil groove and the inner sealing oil edge of the axial 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 bearing oil groove in a direction away from the first-stage return oil groove. A primary return oil groove is sequentially provided along the axial oil groove in a direction away from the first-stage return oil groove. The rear hydrostatic bearing has a rear pressure oil groove facing the main shaft and an axial air groove facing the thrust portion of the main shaft. The two sealing edges of the rear pressure oil groove are provided with a set of rear primary oil grooves and a set of rear secondary oil 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 pressure oil groove and a second throttling oil passage for oil entering the axial oil groove. The rear hydrostatic bearing is provided with a third throttling oil passage for oil entering the rear pressure oil groove and a first air intake passage for air entering the axial air groove.

6. The high-precision grinding wheel spindle structure according to claim 5, characterized in that, The number of the front pressure bearing oil groove, the rear 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 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 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 within the axial oil groove. A small orifice throttling device is installed at the inlet of each of the first, second, and third throttling oil passages.

7. The high-precision grinding wheel spindle structure according to claim 5, 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 outer side. The first oil baffle ring and the primary oil return groove form an annular oil return channel. The secondary oil return groove is located between the first oil baffle ring and the second oil baffle ring.

8. The high-precision grinding wheel spindle structure according to claim 7, characterized in that, The front hydrostatic bearing is provided with a first oil return channel for returning oil to the first-stage oil return groove 1, the first-stage oil return groove 2, and the primary oil return groove. There are several first oil return channels, which are radially distributed in the circumferential direction within the front hydrostatic bearing. The front hydrostatic bearing is also provided with a second oil return channel for returning oil to the first-stage oil return groove 2 and the secondary oil return groove. The inlet of the second oil return channel is located at the lowest position of the first-stage oil return groove 2 and the secondary oil return groove of the assembled front hydrostatic bearing.

9. A high-precision grinding wheel spindle structure according to claim 5, characterized in that, The rear hydrostatic bearing is provided with a third oil return channel for returning oil to the first-stage oil return groove and a fourth oil return channel for returning oil to the second-stage oil return groove. There are several third oil return channels, which are radially distributed in the circumferential direction within the rear hydrostatic bearing. The entrance of the fourth oil return channel is located at the lowest point of the second-stage oil return groove of the assembled rear hydrostatic bearing.

10. A gantry surface grinder, comprising a bed, an X-axis feed unit, a Y-axis feed unit, a Z-axis feed unit, and a high-precision grinding wheel spindle structure as described in any one of claims 1-9, wherein the X-axis feed unit is connected to the bed, the Y-axis feed unit is connected to the X-axis feed unit via hydrostatic guide rails, and the Z-axis feed unit is connected to the Y-axis feed unit via a rolling-sliding composite guide rail, and the machine housing is laterally fixed on the free end of the Z-axis feed unit.

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