Ultra-precise hydrostatic pressure tailstock

Abstract

The invention relates to an ultra-precise hydrostatic pressure tailstock. The tailstock comprises a center, a shaft core, a front bearing, a rear bearing and a shell. The tip is arranged at the front end of the shaft core. The periphery of the shaft core is sequentially sleeved with a front bearing, a shell and a rear bearing from front to back, and the shaft core is in clearance fit with the front bearing and the rear bearing. The front bearing and the rear bearing are both connected with the shell. Oil inlet pipelines are arranged on the rear bearing and the shell, annular slit throttling cavities are formed between the outer walls of the front bearing and the rear bearing and the inner wall of the shell, oil inlet cavities are formed in the front bearing and the rear bearing, and annular oil cavities are formed in the inner walls of the front bearing and the rear bearing. The oil inlet pipeline, the annular slit throttling cavity, the oil inlet cavity and the annular oil cavity are sequentially communicated in the flowing direction of hydraulic oil. Hydraulic oil flowing out of the annular oil cavity can form pressure oil films between the front bearing and the shaft core and between the rear bearing and the shaft core. The bearing has the beneficial effects that when oil is supplied to the oil inlet pipeline at constant pressure, the annular slit throttling cavity formed between the bearing and the shell can be used for throttling the oil inlet cavity in the bearing.

Description

Technical Field

[0001] The present invention relates to the technical field of machine tool processing, in particular to an ultra-precision liquid static pressure tailstock. Background Art

[0002] In the field of machine tool processing, the tailstock is a key component supporting the workpiece, and its performance directly affects the processing accuracy and quality. A hydrostatic tailstock is a support method that uses hydrostatic bearings to separate the relatively moving parts using a high-pressure oil film, thereby achieving pure liquid friction. It has the advantages of high rigidity, high precision, no wear, and good vibration resistance. However, existing hydrostatic tailstocks still have throttling problems:

[0003] Existing hydrostatic tailstocks generally use a constant-pressure oil supply, combined with a throttle for compensation, to adjust the pressure in each oil chamber within the bearing, thereby balancing external loads. Throttling methods are primarily categorized as fixed and variable. Existing equipment generally utilizes more sophisticated fixed throttles (such as orifice and capillary throttles). However, this requires the installation of an equal number of throttles on the tailstock based on the number of oil chambers, increasing the complexity of the tailstock structure. Summary of the Invention

[0004] (1) Technical issues to be resolved

[0005] In view of the above-mentioned shortcomings and deficiencies of the prior art, the present invention provides an ultra-precision hydrostatic tailstock, which solves the technical problem that the existing hydrostatic tailstock adjusts the pressure through a throttle, resulting in a complex tailstock structure.

[0006] (2) Technical solution

[0007] In order to achieve the above objectives, the main technical solutions adopted by the present invention include:

[0008] An embodiment of the present invention provides an ultra-precision hydrostatic tailstock, comprising a center, a shaft core, a front bearing, a rear bearing, and a housing;

[0009] The tip is provided at the front end of the shaft core; the front bearing, the housing and the rear bearing are sequentially sleeved on the outer circumference of the shaft core from front to rear, and the shaft core is loosely fitted with the front bearing and the rear bearing; the front bearing and the rear bearing are both connected to the housing; an oil inlet pipe is provided on the rear bearing and the housing, an annular slit throttling cavity is formed between the outer walls of the front bearing and the rear bearing and the inner wall of the housing, and an oil inlet cavity is provided on the front bearing and the rear bearing, and an annular oil cavity is provided on the inner wall;

[0010] Along the flow direction of the hydraulic oil, the oil inlet pipe, the annular slit throttling chamber, the oil inlet chamber and the annular oil chamber are connected in sequence; the hydraulic oil flowing out of the annular oil chamber can form a pressure oil film between the front bearing and the shaft core and between the rear bearing and the shaft core.

[0011] According to the present invention, a shaft shoulder is provided on the shaft core, the shaft shoulder and the rear bearing are clearance-fitted, and the shaft core can move forward and backward axially relative to the front bearing and the rear bearing;

[0012] A preload oil passage is provided on the rear bearing, a preload cavity communicating with the preload oil passage is provided on the inner periphery of the rear bearing, and part of the shaft shoulder is located in the preload cavity;

[0013] The hydraulic oil introduced into the preload oil passage can flow into the preload chamber, and the hydraulic oil in the preload chamber is used to apply forward axial pressure to the shaft shoulder.

[0014] According to the present invention, the preload oil circuit is connected to the oil outlet circuit of the hydraulic system, a hydraulic proportional valve is provided on the oil outlet circuit, and a pressure sensor is provided in the preload chamber.

[0015] According to the present invention, when the top tip presses the workpiece, the calculation formula of the preload force F of the top tip pressing on the workpiece is:

[0016]

[0017] Wherein, p is the pressure of the hydraulic oil in the pre-compression chamber, D1 is the diameter of the shaft shoulder, and D2 is the diameter of the shaft core.

[0018] According to the present invention, an oil return chamber is enclosed between the inner periphery of the housing, the rear end of the front bearing, the front end of the rear bearing and the outer periphery of the shaft core;

[0019] An oil return pipe communicating with the oil return chamber and the oil return circuit of the hydraulic system is provided on the housing and the rear bearing;

[0020] The hydraulic oil between the front bearing and the shaft core, between the rear bearing and the shaft core, and between the rear bearing and the shaft shoulder can all flow into the oil return pipe through the oil return chamber.

[0021] According to the present invention, sealing bushings are provided on the inner peripheries of the front bearing and the rear bearing, a sealing ring is provided between the sealing bushing and the shaft core, the sealing ring is located on the outside of the annular oil chamber, and a shoulder is provided on the outer periphery of the sealing ring that can press against the side wall of the sealing bushing.

[0022] According to the present invention, the rear bearing, the housing and the front bearing are further connected in sequence to form an air intake duct;

[0023] The sealing ring and the shaft core are loosely matched, and an air groove communicating with the air intake pipe is provided on the inner periphery of the sealing ring;

[0024] The gas in the gas groove can be discharged to the front and rear sides through the gap between the sealing ring and the shaft core.

[0025] According to the present invention, the gap between the sealing ring and the shaft core is smaller than the gaps between the front bearing and the rear bearing and the shaft core respectively.

[0026] According to the present invention, there are multiple oil inlet chambers, and the multiple oil inlet chambers are opened in the front bearing and the rear bearing in annular intervals, and the oil inlet chambers extend radially, and the two ends of the oil inlet chamber are respectively connected to the corresponding annular slit throttling chamber and annular oil chamber.

[0027] According to the present invention, when the workpiece needs to be disassembled, oil is not passed through the pre-compression chamber, and the shaft core can move forward and backward in the axial direction relative to the front bearing and the rear bearing;

[0028] When the top tip is pressed against the workpiece to clamp the workpiece, hydraulic oil is introduced into the pre-tightening oil circuit, and the hydraulic oil flows into the pre-compression chamber. The hydraulic oil in the pre-compression chamber is used to apply forward axial pressure to the shaft shoulder.

[0029] When it is necessary to process a workpiece, hydraulic oil is introduced into the oil inlet pipe, and the hydraulic oil flows through the annular slit throttling chamber, the oil inlet chamber and the annular oil chamber in sequence. The hydraulic oil flowing out of the annular oil chamber can form a pressure oil film between the front bearing and the shaft core and between the rear bearing and the shaft core.

[0030] (3) Beneficial effects

[0031] The beneficial effects of the present invention are:

[0032] The ultra-precision hydrostatic tailstock of the present invention, when machining a workpiece, allows hydraulic oil flowing from the annular oil chamber to form a pressure oil film between the intermittently mated front bearing and the shaft core, and between the rear bearing and the shaft core, to support the shaft core. This allows the front and rear bearings to form hydrostatic bearings, thereby eliminating mechanical friction between the rotating component (shaft core) and the fixed component (bearing), improving the rotational accuracy of the shaft core. The rotational accuracy can reach 0.05 μm, less than 0.1 μm, meeting ultra-precision requirements, thus forming an ultra-precision hydrostatic tailstock. Furthermore, the absence of mechanical friction between the shaft core and the bearings extends the service life of the shaft core. Furthermore, when constant pressure oil is supplied to the oil inlet pipeline, the annular slit throttling chamber formed between the bearing and the housing throttles the oil inlet chamber on the bearing to regulate the oil pressure within the annular oil chamber. This throttling method replaces an external throttle, eliminating the need to install an equal number of external throttles based on the number of oil inlet chambers provided, simplifying the tailstock structure. The annular slit throttling chamber structure is also less prone to clogging, making it easier to process and maintain. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 A three-dimensional schematic diagram of the ultra-precision hydrostatic tailstock of the present invention;

[0034] Figure 2 for Figure 1 Right view;

[0035] Figure 3 for Figure 1 Cross-sectional view at AA;

[0036] Figure 4 for Figure 3 Enlarged view of point E in the figure;

[0037] Figure 5 for Figure 3 The enlarged view of point F in the figure;

[0038] Figure 6 for Figure 3 Schematic diagram of the air and oil supply paths when machining a workpiece (arrows indicate the flow paths of compressed air and hydraulic oil);

[0039] Figure 7 for Figure 6 Enlarged view of point B in FIG.

[0040] Figure 8 for Figure 2 Cross-sectional view at CC;

[0041] Figure 9 for Figure 2 Schematic diagram of the return oil path (the arrow indicates the flow path of the hydraulic oil);

[0042] Figure 10 for Figure 2 Cross-sectional view at DD;

[0043] Figure 11 for Figure 10 Schematic diagram of the oil supply path when the center 1 is pressed against the workpiece to clamp the workpiece (the arrow indicates the flow path of the hydraulic oil);

[0044] Figure 12 for Figure 11 Enlarged view of point G;

[0045] Figure 13 This is a three-dimensional schematic diagram of the front bearing.

[0046] [Description of Reference Numerals]

[0047] 1: Top;

[0048] 2: shaft core; 21: shaft shoulder;

[0049] 3: front bearing; 31: front annular slit throttle chamber; 32: forward oil chamber; 33: front annular oil chamber; 34: forward oil groove; 35: front air intake hole; 36: thrust chamber; 37: front oil return hole;

[0050] 4: Rear bearing; 41: Rear annular slit throttle chamber; 42: Rear oil chamber; 43: Rear annular oil chamber; 44: Preload oil passage; 45: Preload chamber; 46: Oil inlet; 47: Rear oil tank; 48: Air inlet; 49: Rear air inlet hole; 410: First rear oil return hole; 411: Second rear oil return hole; 412: Oil return port;

[0051] 5: Housing; 51: Oil inlet; 52: Front oil hole; 53: Rear oil hole; 54: Air inlet; 55: Oil return;

[0052] 6: sealing bushing; 61: first air inlet;

[0053] 7: sealing ring; 71: shoulder; 72: air groove; 73: second air inlet;

[0054] H: oil inlet pipe;

[0055] I: oil return chamber;

[0056] J: oil return pipe;

[0057] K: Intake duct. DETAILED DESCRIPTION

[0058] In order to better explain the present invention and facilitate understanding, the present invention is described in detail below with reference to the accompanying drawings and through specific embodiments. Figure 6 The "left" and "right" orientations are for reference.

[0059] See also Figure 1-13 The ultra-precision liquid hydrostatic tailstock proposed in an embodiment of the present invention includes a top 1, a shaft core 2, a front bearing 3, a rear bearing 4 and a housing 5.

[0060] The tip 1 is arranged at the front end of the shaft core 2. The outer periphery of the shaft core 2 is sequentially sleeved with the front bearing 3, the housing 5 and the rear bearing 4 from front to back, and the shaft core 2 is clearance-fitted with the front bearing 3 and the rear bearing 4. The front bearing 3 and the rear bearing 4 are both connected to the housing 5. An oil inlet pipe H is provided on the rear bearing 4 and the housing 5, and an annular slit throttling cavity is formed between the outer walls of the front bearing 3 and the rear bearing 4 and the inner wall of the housing 5. An oil inlet cavity is provided in the front bearing 3 and the rear bearing 4, and an annular oil cavity is provided on the inner wall. Along the flow direction of the hydraulic oil, the oil inlet pipe H, the annular slit throttling cavity, the oil inlet cavity and the annular oil cavity are connected in sequence. The hydraulic oil flowing out of the annular oil cavity can form a pressure oil film between the front bearing 3 and the shaft core 2 and between the rear bearing 4 and the shaft core 2.

[0061] When machining a workpiece, this ultra-precision hydrostatic tailstock allows hydraulic oil flowing from the annular oil chamber to form a pressure oil film between the intermittently fitted front bearing 3 and shaft core 2, and between the rear bearing 4 and shaft core 2, to support the shaft core 2. This allows the front bearing 3 and rear bearing 4 to form a hydrostatic bearing, eliminating mechanical friction between the rotating shaft core 2 and the fixed bearings. This improves the rotational accuracy of the shaft core 2, reaching 0.05 μm, less than 0.1 μm, meeting ultra-precision requirements, thus forming an ultra-precision hydrostatic tailstock. Furthermore, the lack of mechanical friction between the shaft core 2 and the bearings also extends the service life of the shaft core 2. Furthermore, when oil is supplied to the oil inlet pipe H at a constant pressure, the annular slit throttling cavity formed between the bearing and the housing 5 can throttle the oil inlet cavity on the bearing to adjust the oil pressure in the annular oil cavity. This throttling method replaces the external throttle, and there is no need to install the same number of external throttles according to the number of oil inlet cavities set, which simplifies the tailstock structure. In addition, the structure of the annular slit throttling cavity is not prone to blockage, and is easy to process and maintain.

[0062] See also Figure 3 Specifically, the front bearing 3 and the rear bearing 4 are both interference fit with the housing 5 and are both screwed to the housing 5. Preferably, O-rings are provided on the mating end surfaces of the front bearing 3 and the housing 5, and on the mating end surfaces of the rear bearing 4 and the housing 5, to prevent leakage of hydraulic oil.

[0063] Furthermore, in order to balance the external load, the oil inlet cavity is set as:

[0064] See also Figure 13 There are multiple oil inlet chambers, which are annularly spaced and opened in the front bearing 3 and the rear bearing 4. The oil inlet chambers extend radially, and the two ends of the oil inlet chambers are respectively connected to the corresponding annular slit throttling chamber and the annular oil chamber.

[0065] By providing a plurality of oil inlet chambers at annular intervals on the front bearing 3 and the rear bearing 4, the hydraulic oil in the plurality of oil inlet chambers can have a pressure difference under the action of an external load, and the bearing force formed by the pressure difference can balance the external load.

[0066] Preferably, the number of oil inlet chambers is 6.

[0067] See also Figure 4 Specifically, the oil inlet chamber includes a radially extending forward oil chamber 32 disposed within the front bearing 3, and a radially extending rear oil inlet chamber 42 disposed on the rear bearing 4. The annular slit throttling chamber includes a front annular slit throttling chamber 31 disposed between the outer wall of the front bearing 3 and the inner wall of the housing 5, and a rear annular slit throttling chamber 41 disposed between the outer wall of the rear bearing 4 and the inner wall of the housing 5. The annular oil chamber includes a front annular oil chamber 33 disposed on the inner wall of the front bearing 3, and a rear annular oil chamber 43 disposed on the inner wall of the rear bearing 4.

[0068] See also Figure 4 Furthermore, the outer walls of the front bearing 3 and the rear bearing 4 each have an oil inlet groove located outside the annular slit throttle cavity. Multiple oil inlet grooves are provided, and the multiple oil inlet cavities are annularly spaced and correspond one-to-one with the multiple oil inlet cavities. The oil inlet groove on the outer wall of the front bearing 3 is located in front of the annular slit throttle cavity, while the oil inlet groove on the outer wall of the rear bearing 4 is located in the rear of the annular slit throttle cavity.

[0069] Specifically, the oil inlet groove includes a forward oil groove 34 opened on the outer wall of the front bearing 3 and located in front of the front annular slit throttling cavity 31, and a rear oil inlet groove 47 opened on the outer wall of the rear bearing 4 and located in the rear side of the rear annular slit throttling cavity 41.

[0070] Along the flow direction of the hydraulic oil, the oil inlet pipe H, the forward oil groove 34, the front annular slit throttling chamber 31, the forward oil chamber 32 and the front annular oil chamber 33 are connected in sequence, and the oil inlet pipe H, the rear oil groove 47, the rear annular slit throttling chamber 41, the rear oil chamber 42 and the rear annular oil chamber 43 are connected in sequence.

[0071] See also Figure 4 Furthermore, along the flow direction of the hydraulic oil, the oil inlet pipeline H includes an oil inlet port 46 provided on the rear bearing 4 and an oil inlet passage 51 provided on the housing 5. Both the oil inlet port 46 and the oil inlet passage 51 extend axially along the shaft core 2. The oil inlet port 46 is connected to the oil inlet passage of the hydraulic system.

[0072] See also Figure 4Specifically, a front oil hole 52 and a rear oil hole 53 are spaced apart in the front and rear directions within the housing 5 and extend radially. The front oil hole 52 has two ends connected to the oil inlet passage 51 and the front annular slit throttle chamber 31, while the rear oil hole 53 has two ends connected to the oil inlet passage 51 and the rear annular slit throttle chamber 41.

[0073] See also Figure 6 Based on the above settings, the oil inlet path of the ultra-precision hydrostatic tailstock into the annular oil chamber is:

[0074] The hydraulic oil discharged from the oil inlet circuit of the hydraulic system flows through the oil inlet 46 and the oil inlet circuit 51 in sequence, and a part of it enters the front annular oil chamber 33 through the front oil groove 34, the front annular slit throttling chamber 31 and the front oil chamber 32, and the other part enters the rear annular oil chamber 43 through the rear oil groove 47, the rear annular slit throttling chamber 41 and the rear oil chamber 42 in sequence.

[0075] Furthermore, in order to expand the axial movement stroke of the shaft core 2 and avoid mechanical friction during the axial movement of the shaft core 2, the ultra-precision liquid hydrostatic tailstock further includes the following configurations:

[0076] See also Figure 10 and Figure 11 A shoulder 21 is provided on the shaft core 2. The peripheral wall of the shoulder 21 forms a clearance fit with the rear bearing 4, and the shaft core 2 is able to move forward and backward axially relative to the front bearing 3 and the rear bearing 4. A preload oil passage 44 is provided on the rear bearing 4. A preload cavity 45 is defined on the inner circumference of the rear bearing 4, communicating with the preload oil passage 44. A portion of the shoulder 21 is located within the preload cavity 45. Hydraulic oil entering the preload oil passage 44 enters the preload cavity 45, where it applies forward axial pressure to the shoulder 21.

[0077] When it is necessary to disassemble or assemble the workpiece, the pre-stressing chamber 45 is blocked from oil, and the shoulder 21 can move axially forward and backward in the pre-stressing chamber 45, that is, the shaft core 2 can move axially forward and backward relative to the front bearing 3 and the rear bearing 4, so as to adjust the position of the top 1, facilitate clamping and disassembling the workpiece, and improve processing efficiency. Among them, the axial movement length of the shaft core 2 is the axial length of the pre-stressing chamber 45, preferably 30-50mm. Compared with the traditional liquid hydrostatic tailstock that supports the shaft core through a thrust bearing, the shaft core 2 cannot move axially or can only move within a very small range. The present application expands the axial movement length of the shaft core 2 by setting a pre-stressing chamber 45 on the rear bearing 4, and the shoulder 21 can move axially forward and backward in the pre-stressing chamber 45.

[0078] When tip 1 presses against a workpiece to clamp it, oil is introduced into preload chamber 45. The hydraulic oil in preload chamber 45 propels shaft core 2 and tip 1 axially forward via shoulder 21, thereby adjusting the preload force exerted by tip 1 against the workpiece. Simultaneously, the hydraulic oil in preload chamber 45 flows forward through the gap between rear bearing 4 and shoulder 21, and backward through the gap between rear bearing 4 and shaft core 2, forming a supporting oil film within the gaps. This allows shaft core 2 to move forward axially relative to rear bearing 4 without mechanical contact, thus avoiding the mechanical friction associated with mechanical propulsion.

[0079] Preferably, the pre-tightening oil circuit 44 is connected to the oil outlet circuit of the hydraulic system, a hydraulic proportional valve is provided on the oil outlet circuit, a pressure sensor is provided in the pre-load chamber 45, the oil pressure in the pre-load chamber 76 is adjusted by the hydraulic proportional valve, and the oil pressure is fed back in real time by the pressure sensor, thereby adjusting the pre-tightening force of the top 1 pressing on the workpiece to stably clamp the workpiece.

[0080] Specifically, see Figure 11 When the top 1 presses the workpiece, the calculation formula for the preload force F of the top 1 pressing on the workpiece is:

[0081]

[0082] Wherein, p is the pressure of the hydraulic oil in the pre-compression chamber 45, D1 is the diameter of the shaft shoulder 21, and D2 is the diameter of the shaft core 2. It should be noted that the diameter of the shaft core 2 refers to the diameter of the shaft body.

[0083] The method for adjusting the preload force F is: according to the required value of the preload force F, the preload force F, the shoulder 21 of the shaft core 2 used and the diameter of the shaft core 2 are substituted into the above formula, and the pressure p of the hydraulic oil in the preload chamber 45 is calculated, and then the oil pressure value in the preload chamber 76 is adjusted to p by the hydraulic proportional valve.

[0084] Referring to the figure further, the oil return structure of this ultra-precision hydrostatic tailstock is set as follows:

[0085] See also Figure 8 and Figure 9 The inner periphery of the housing 5, the rear end of the front bearing 3, the front end of the rear bearing 4, and the outer periphery of the shaft core 2 enclose an oil return chamber I. The housing 5 and the rear bearing 4 are provided with an oil return pipe J that connects the oil return chamber I with the return oil circuit of the hydraulic system.

[0086] The hydraulic oil between the front bearing 3 and the shaft core 2, between the rear bearing 4 and the shaft core 2, and between the rear bearing 4 and the shaft shoulder 21 can flow into the return oil pipe J through the return oil chamber I and flow back to the return oil circuit of the hydraulic system, filtering and cooling the hydraulic oil in the hydraulic system.

[0087] Specifically, a front oil return hole 37 is defined in the front bearing 3, the two ends of which communicate with the front side of the front annular oil chamber 33 and the oil return chamber I. A thrust chamber 36 is also defined in the inner wall of the front bearing 3, the two ends of which communicate with the rear side of the annular oil chamber and the oil return chamber I.

[0088] A portion of the hydraulic oil in the front annular oil chamber flows forward through the slit between the inner wall of the front bearing 3 and the shaft core 2, and the front return oil hole 37, and then enters the return oil chamber I. The other portion of the hydraulic oil flows backward through the slit between the inner wall of the front bearing 3 and the shaft core 2, and the thrust chamber 36 and then enters the return oil chamber I.

[0089] The thrust chamber 36 is used to prevent the shaft shoulder 21 from mechanically contacting the front bearing 3 . When the shaft core 2 moves forward in the axial direction, the shaft shoulder 21 will be pushed backward by the hydraulic oil in the thrust chamber 36 .

[0090] Specifically, a first rear oil return hole 410 and a second rear oil return hole 411 are opened on the rear bearing 4, and the two ends of the first rear oil return hole 410 are respectively connected to the front side of the rear annular oil chamber 43 and the oil return chamber I, and the two ends of the second rear oil return hole 411 are respectively connected to the rear side of the rear annular oil chamber 43 and the oil return chamber I.

[0091] A portion of the hydraulic oil in the rear annular oil chamber 43 flows forward through the slit between the inner wall of the rear bearing 4 and the shaft core 2, and the first rear oil return hole 410 to enter the oil return chamber I, and the other portion of the hydraulic oil flows backward through the slit between the inner wall of the rear bearing 4 and the shaft core 2, and the second rear oil return hole 411 to enter the oil return chamber I.

[0092] More specifically, the first rear oil return hole 410 is located at the rear side of the pre-compression chamber 45 .

[0093] A portion of the hydraulic oil in the pre-load chamber 45 flows forward through the slit between the inner wall of the rear bearing 4 and the shaft shoulder 21 and enters the oil return chamber I, and another portion of the hydraulic oil flows backward through the slit between the inner wall of the rear bearing 4 and the shaft core 2, as well as the first rear oil return hole 410, and enters the oil return chamber I.

[0094] See also Figure 3-7 Furthermore, in order to improve the sealing performance, the ultra-precision liquid hydrostatic tailstock also includes the following settings:

[0095] A sealing bushing 6 is provided on the inner periphery of the front end of the front bearing 3 and the inner periphery of the rear end of the rear bearing 4. A sealing ring 7 is provided between the sealing bushing 6 and the shaft core 2 to prevent the hydraulic oil in the annular oil chamber from leaking out of the tailstock.

[0096] Preferably, the outer periphery of the sealing ring 7 is provided with a shoulder 71 which can press against the side wall of the sealing bushing 6 so that the hydraulic oil flowing out of the front annular oil chamber 33 forward and the rear annular oil chamber 43 backward can press the corresponding sealing ring 7 against the sealing bushing 6.

[0097] Specifically, the sealing ring 7 and the sealing bushing 6 are interference fit, and the sealing bushing 6 is connected to the front bearing 3 and the rear bearing 4 by screws.

[0098] Preferably, in order to further improve the sealing performance, the ultra-precision liquid hydrostatic tailstock further includes the following configurations:

[0099] The rear bearing 4, housing 5, and front bearing 3 are also connected in sequence through an air intake duct K. The sealing ring 7 and shaft core 2 are clearance-fitted, and an air groove 72 is provided on the inner circumference of the sealing ring 7, which is connected to the air intake duct K. Gas in the air groove 72 can be discharged to the front and rear sides through the gap between the sealing ring 7 and shaft core 2.

[0100] When a workpiece needs to be machined, compressed gas is introduced into the gas groove 72 through the gas inlet pipe K. A portion of the gas in the gas groove 72 can flow into the tailstock through the gap between the sealing ring 7 and the shaft core 2, preventing hydraulic oil from leaking from the sealing ring 7. This portion of gas can flow back into the oil chamber I along with the hydraulic oil. Another portion of the gas can flow out of the tailstock through the gap between the sealing ring 7 and the shaft core 2, preventing impurities such as external cutting fluid and chips from entering the tailstock, thereby increasing the service life of the tailstock.

[0101] Specifically, the intake duct K includes an axially extending intake port 48 provided on the rear bearing 4 and an axially extending intake passage 54 provided on the housing 5. The intake port 48 is connected to the air supply pump. A radially extending front intake port 35 is defined within the front bearing 3, and a radially extending rear intake port 49 is defined within the rear bearing 4. A first intake port 61 communicating with the front intake port 35 is defined within the sealing bushing 6, and a second intake port 73 communicating with the rear intake port 49 is defined within the sealing ring 7. Both the first intake port 61 and the second intake port 73 extend radially.

[0102] See also Figure 6 and Figure 7 Based on the above arrangement, when a workpiece needs to be processed, the air supply path to the air groove 72 of the sealing ring 7 is:

[0103] The air supply pump is turned on and compressed air is introduced into the air inlet 48 and flows through the air inlet path 54. A portion of the air discharged from the air inlet path 54 enters the air groove 72 of the front sealing ring 7 through the front air inlet hole 35, the first air inlet hole 61, and the second air inlet hole 73 in sequence. Another portion of the air discharged from the air inlet path 54 enters the air groove 72 of the rear sealing ring 7 through the rear air inlet hole 49, the first air inlet hole 61, and the second air inlet hole 73 in sequence.

[0104] Preferably, the sealing ring 7 is made of a material with a lower elastic modulus than the shaft core 2 , the front bearing 3 and the rear bearing 4 , such as copper or aluminum.

[0105] Preferably, in order to prevent the shaft core 2, the front bearing 3 and the rear bearing 4 from being damaged when the cutter is struck, the ultra-precision liquid hydrostatic tailstock further includes the following configurations:

[0106] The gap between the sealing ring 7 and the shaft core 2 is smaller than the gap between the front bearing 3 and the rear bearing 4 and the shaft core 2, so as to prevent the shaft core 2 from colliding with the front bearing 3 or the rear bearing 4 when the knife hits.

[0107] In the description of the present invention, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of the technical features indicated. Therefore, a feature specified as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, "plurality" means two or more, unless otherwise specifically defined.

[0108] In this disclosure, unless otherwise specified or limited, terms such as "mounted," "connected," "connect," and "fixed" should be interpreted broadly. For example, they may refer to fixed connections, removable connections, or integration. They may refer to mechanical connections or electrical connections; direct connections or indirect connections through an intermediary; and they may refer to internal communication between two components or the interaction between two components. Those skilled in the art will understand the specific meanings of these terms in this disclosure based on the specific circumstances.

[0109] In the present invention, unless otherwise expressly specified or limited, when a first feature is "above" or "below" a second feature, it may mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediate medium. Furthermore, when a first feature is "above," "above," or "above" a second feature, it may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is at a higher level than the second feature. When a first feature is "below," "below," or "below" a second feature, it may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is at a lower level than the second feature.

[0110] In the description of this specification, the terms "one embodiment", "some embodiments", "embodiments", "examples", "specific examples" or "some examples" refer to the specific features, structures, materials or characteristics described in conjunction with the embodiment or example and included in at least one embodiment or example of the present invention. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine different embodiments or examples described in this specification and features of different embodiments or examples, unless they are mutually inconsistent.

[0111] Although the embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and are not to be construed as limitations on the present invention. A person skilled in the art may alter, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. An ultra-precision hydrostatic tailstock, characterized in that: It comprises a top (1), a shaft core (2), a front bearing (3), a rear bearing (4) and a housing (5); The tip (1) is arranged at the front end of the shaft core (2); the outer periphery of the shaft core (2) is sequentially sleeved with the front bearing (3), the housing (5) and the rear bearing (4) from front to rear, and the shaft core (2) is clearance-fitted with the front bearing (3) and the rear bearing (4); the front bearing (3) and the rear bearing (4) are both connected to the housing (5); an oil inlet pipe (H) is provided on the rear bearing (4) and the housing (5); an annular slit throttling cavity is formed between the outer walls of the front bearing (3) and the rear bearing (4) and the inner wall of the housing (5); an oil inlet cavity is provided on the front bearing (3) and the rear bearing (4), and an annular oil cavity is provided on the inner wall of the housing (5); Along the flow direction of the hydraulic oil, the oil inlet pipe (H), the annular slit throttling chamber, the oil inlet chamber and the annular oil chamber are connected in sequence; the hydraulic oil flowing out of the annular oil chamber can form a pressure oil film between the front bearing (3) and the shaft core (2) and between the rear bearing (4) and the shaft core (2).

2. The ultra-precision hydrostatic tailstock according to claim 1, characterized in that: A shaft shoulder (21) is provided on the shaft core (2), a peripheral wall of the shaft shoulder (21) and the rear bearing (4) are clearance-matched, and the shaft core (2) can move forward and backward along the axial direction relative to the front bearing (3) and the rear bearing (4); A preload oil passage (44) is provided on the rear bearing (4), a preload cavity (45) communicating with the preload oil passage (44) is provided on the inner periphery of the rear bearing (4), and a portion of the shaft shoulder (21) is located in the preload cavity (45); The hydraulic oil introduced into the preload oil circuit (44) can flow into the preload chamber (45), and the hydraulic oil in the preload chamber (45) is used to apply forward axial pressure to the shaft shoulder (21).

3. The ultra-precision hydrostatic tailstock according to claim 2, characterized in that: The preload oil circuit (44) is connected to the oil outlet circuit of the hydraulic system. A hydraulic proportional valve is provided on the oil outlet circuit. A pressure sensor is provided in the preload chamber (45).

4. The ultra-precision hydrostatic tailstock according to claim 2, characterized in that: When the top (1) presses against the workpiece, the calculation formula for the preload force F of the top (1) pressing against the workpiece is: Wherein, p is the pressure of the hydraulic oil in the pre-compression chamber (45), D1 is the diameter of the shaft shoulder (21), and D2 is the diameter of the shaft core (2).

5. The ultra-precision hydrostatic tailstock according to claim 2, characterized in that: An oil return chamber (I) is enclosed between the inner periphery of the housing (5), the rear end of the front bearing (3), the front end of the rear bearing (4), and the outer periphery of the shaft core (2); An oil return pipe (J) is provided on the housing (5) and the rear bearing (4) to communicate with the oil return chamber (I) and the oil return circuit of the hydraulic system; The hydraulic oil between the front bearing (3) and the shaft core (2), between the rear bearing (4) and the shaft core (2), and between the rear bearing (4) and the shaft shoulder 21 can all flow into the oil return pipe (J) through the oil return chamber (I).

6. The ultra-precision hydrostatic tailstock according to claim 1, characterized in that: A sealing bushing (6) is provided on the inner periphery of the front bearing (3) and the rear bearing (4); a sealing ring (7) is provided between the sealing bushing (6) and the shaft core (2); the sealing ring (7) is located outside the annular oil cavity; and a shoulder (71) capable of pressing against the side wall of the sealing bushing (6) is provided on the outer periphery of the sealing ring (7).

7. The ultra-precision hydrostatic tailstock according to claim 6, characterized in that: The rear bearing (4), the housing (5) and the front bearing (3) are also sequentially connected to form an air intake pipe (K); The sealing ring (7) and the shaft core (2) are clearance-fitted, and an air groove (72) communicating with the air intake pipe (K) is provided on the inner periphery of the sealing ring (7); The gas in the gas groove (72) can be discharged to the front and rear sides through the gap between the sealing ring (7) and the shaft core (2).

8. The ultra-precision hydrostatic tailstock according to claim 7, characterized in that: The gap between the sealing ring (7) and the shaft core (2) is smaller than the gap between the front bearing (3) and the rear bearing (4) and the shaft core (2).

9. The ultra-precision hydrostatic tailstock according to claim 1, characterized in that: The oil inlet chambers are provided in a plurality, and the plurality of oil inlet chambers are opened in the front bearing (3) and the rear bearing (4) at annular intervals, and the oil inlet chambers extend radially, and the two ends of the oil inlet chambers are respectively connected to the corresponding annular slit throttling chamber and the annular oil chamber.

10. The ultra-precision hydrostatic tailstock according to claim 2, characterized in that: When the workpiece needs to be disassembled, oil is not passed through the pre-compression chamber (45), and the shaft core (2) can move forward and backward along the axial direction relative to the front bearing (3) and the rear bearing (4); When the top (1) is pressed against a workpiece to clamp the workpiece, hydraulic oil is introduced into the pre-tightening oil circuit (44), and the hydraulic oil flows into the pre-stressing chamber (45). The hydraulic oil in the pre-stressing chamber (45) is used to apply forward axial pressure to the shaft shoulder (21); When a workpiece needs to be machined, hydraulic oil is introduced into the oil inlet pipe (H), and the hydraulic oil flows through the annular slit throttling chamber, the oil inlet chamber, and the annular oil chamber in sequence. The hydraulic oil flowing out of the annular oil chamber can form a pressure oil film between the front bearing (3) and the shaft core (2) and between the rear bearing (4) and the shaft core (2).

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