Hydrostatic spindle structure with self-centering telescopic tailstock

Abstract

The present application relates to the technical field of centerless spindle, especially to a liquid static pressure spindle structure with self-centering telescopic center, comprising: an outer shell, a core shaft, a support body, a telescopic center, a limiting piece and a linear driving piece, the core shaft is arranged in the inner hole of the outer shell; the telescopic center is arranged in the inner hole of the core shaft, and the outer cylindrical surface of the telescopic center is provided with a guide groove; the limiting piece penetrates the core shaft along the radial direction and is embedded in the guide groove, and the linear driving piece drives the telescopic center to make axial telescopic action in the core shaft; the core shaft is provided with a guide section and a centering section, the inner hole wall of the centering section is inwardly gathered towards the end face, forming a guide cone surface; the telescopic center is provided with a center section, a cone section and a sliding shaft section; the cone section is matched with the guide cone surface, and a plurality of guide belts are arranged on the outer cylindrical surface of the sliding shaft section, and the guide belts are slidingly matched with the inner hole wall of the guide section. Through the guide cone surface and the cone section, the self-centering of the telescopic center is realized; and the plurality of guide belts and the guide section form multi-point sliding support, effectively inhibiting periodic radial runout.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of center mandrel, and particularly relates to a liquid static pressure spindle structure with a self-centering telescopic center mandrel. BACKGROUND

[0002] In the machining process of a ball core of a large ball valve, the outer circle accuracy of the clamping position at both ends of the ball core directly determines the positioning stability and the final product quality in the subsequent machining. Therefore, in the machining process, firstly, the center holes at both ends of the ball core are clamped by the telescopic center mandrel, and the outer circle of the clamping position of the ball core is ground; after the outer circle grinding is completed, the chuck is switched to clamp the ground outer circle, and the telescopic center mandrel is retracted, and the subsequent machining process of the ball core is carried out.

[0003] In the prior art, the center mandrel spindle structure mainly comprises an outer shell, a telescopic center mandrel, a mandrel and a double-acting oil cylinder. The outer shell provides mounting support for the overall structure. The mandrel is rotationally arranged in the inner hole of the outer shell through a bearing set. The telescopic center mandrel is coaxially arranged in the inner hole of the mandrel and can move axially along the mandrel. The double-acting oil cylinder is used as a driving component and controls the telescopic center mandrel to extend or retract axially along the mandrel through a hydraulic oil circuit. At the same time, when the outer circle of the clamping position of the ball core is ground, the telescopic center mandrel mechanism needs to rotate synchronously with the mandrel.

[0004] However, in order to meet the requirement of axial movement of the telescopic center mandrel, there must be a matching gap between the telescopic center mandrel and the inner hole of the mandrel. When the telescopic center mandrel rotates synchronously with the mandrel at a high speed, the centrifugal force drives the telescopic center mandrel to deviate or swing to the outside of the matching gap, which causes the telescopic center mandrel to periodically jump radially. The radial jumping directly causes the coaxiality deviation of the telescopic center mandrel and the mandrel to periodically fluctuate, and further causes the outer circle of the clamping position of the ball core to form obvious waviness defects in the grinding process, which destroys the stability and positioning accuracy of the chuck clamping in the subsequent machining process, and finally causes the overall machining quality of the ball core to decrease. SUMMARY

[0005] The technical problem to be solved by the present application is to provide a liquid static pressure spindle structure with a self-centering telescopic center mandrel, which effectively solves the problems in the background art.

[0006] In order to achieve the above-mentioned purpose, the technical scheme adopted by the present application is as follows:

[0007] An outer shell;

[0008] A mandrel is coaxially arranged in the inner hole of the outer shell, and a limiting piece is arranged on the side wall of the mandrel in the radial direction;

[0009] A support body supports and realizes the rotation of the mandrel relative to the outer shell;

[0010] A telescopic center is arranged in the inner hole of the mandrel, which has a guide groove on the outer cylindrical surface to accommodate the end of the limiting member;

[0011] A linear driving member is arranged at the rear end of the mandrel to drive the telescopic center to axially extend and retract in the mandrel;

[0012] The inner hole of the mandrel is provided with a guide section and a centering section in the axial direction, and the inner hole wall of the centering section converges inwardly towards the end face to form a guide cone surface;

[0013] The telescopic center is sequentially provided with a center section, a taper section and a sliding shaft section in the axial direction from the front end to the rear end;

[0014] The taper section cooperates with the guide cone surface, and the outer cylindrical surface of the sliding shaft section is provided with a plurality of guide bands in the axial direction, which are in sliding cooperation with the inner hole wall of the guide section.

[0015] Further, an auxiliary guide section is arranged between the center section and the taper section;

[0016] The diameter of the auxiliary guide section is equal to the minimum diameter of the guide cone surface.

[0017] Further, the telescopic center is provided with at least two groups of guide bands in the axial direction;

[0018] One group of guide bands is arranged at the position close to the taper section of the telescopic center, and the other group is arranged at the position close to the linear driving member;

[0019] And the guide groove is located between the two groups of guide bands.

[0020] Further, one group of guide bands includes at least two guide rings arranged in the axial direction;

[0021] The outer cylindrical surface of the telescopic center is provided with a ring groove, and the guide ring is embedded in the ring groove, and the outer cylindrical surface protruding from the ring groove is in sliding contact with the inner hole wall of the mandrel.

[0022] Further, the guide ring is provided with a notch in the circumferential direction.

[0023] Further, the telescopic center includes a first shaft section, a second shaft section and a guide shaft section, and the first shaft section and the second shaft section are connected in the threaded hole of the guide shaft section through the threaded shaft section at the end;

[0024] The guide grooves are uniformly arranged on the outer cylindrical surface of the guide shaft section in the circumferential direction and are arranged in the axial direction;

[0025] At least one group of guide bands is arranged on the first shaft section and the second shaft section;

[0026] The elastic members are arranged between the guide shaft section and the stepped surfaces of the first shaft section and the second shaft section, and the moving stroke of the limiting member along the guide groove is greater than the axial length of the guide shaft section.

[0027] Further, the axial length of the guide shaft section is greater than the sum of the screwing axial section lengths of the first shaft section and the second shaft section.

[0028] Further, the elastic members include a disc spring group and a ring pressing plate.

[0029] The limiting member slides in the guide groove and drives the ring pressing plate to move towards the stepped surface, thereby compressing the disc spring group.

[0030] Further, the outer edge of the disc spring group is in abutting cooperation with the outer edge of the ring pressing plate.

[0031] The limiting member is embedded in the end of the guide groove and abuts at the position of the outer edge of the ring pressing plate, and the plurality of limiting members distributed along the circumference abut at the end of the outer edge of the ring pressing plate to jointly form a force ring surface.

[0032] Further, the support body includes a front bearing group and a rear bearing group.

[0033] The front bearing group is arranged at the front end of the mandrel, the rear bearing group is arranged at the rear end of the mandrel, and a thrust ring is arranged at the end of the front bearing group close to the rear bearing group.

[0034] The beneficial effects of the present application are as follows: the taper surface of the mandrel is in abutting cooperation with the taper section of the telescopic center, when the linear driving member pushes the telescopic center to extend, the taper section slides along the guide taper surface, the self-centering property of the taper surface is utilized to automatically correct the axis deviation, the axis of the telescopic center is forced to coincide with the axis of the mandrel, and active centering is realized; a plurality of guide belts are distributed along the axial direction, and the guide belts form multi-point sliding support with the guide section in the hole of the mandrel, the gap between the telescopic center and the mandrel is dispersed to the plurality of guide belts, when the telescopic center rotates with the mandrel, the plurality of guide belts provide radial support force from different axial positions, an anti-deviation resultant force is formed, the telescopic center is prevented from being deviated to the outside of the gap by the centrifugal force, periodic radial runout is effectively suppressed, the stability and positioning accuracy of the subsequent chuck clamping outer circle are ensured, and the overall machining quality of the ball valve ball core is ensured. BRIEF DESCRIPTION OF DRAWINGS

[0035] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description only show some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained from these drawings without any creative effort.

[0036] Figure 1 Schematic view of sectional structure of telescopic center in extended state;

[0037] Figure 2 Schematic view of sectional structure of telescopic center in retracted state;

[0038] Figure 3 Schematic view of structure of mandrel;

[0039] Figure 4 Schematic view of structure of telescopic center;

[0040] Figure 5 Schematic view of Figure 4 Enlarged view of part C of

[0041] Figure 6 Enlarged view of part D of Figure 4

[0042] Enlarged view of part A of Figure 7 Figure 1 Enlarged view of part B of

[0043] Figure 8 Figure 1 Enlarged view of part B of

[0044] Figure 9 Axonometric view of telescopic center;

[0045] Figure 10 Schematic view of distribution of limiting member and guide groove;

[0046] Figure 11 Schematic view of state of limiting member compressing elastic member of telescopic center in extended state.

[0047] Reference signs: 1, outer housing; 2, mandrel; 21, guide section; 22, centering section; 3, support body; 31, front bearing set; 32, rear bearing set; 4, telescopic center; 4a, guide groove; 4b, center section; 4c, taper section; 41, first shaft section; 42, second shaft section; 43, guide shaft section; 44, elastic member; 441, disc spring set; 442, ring pressing plate; 411, guide band; 411a, guide ring; 4d, auxiliary guide section; 5, limiting member; 6, linear driving member. DETAILED DESCRIPTION ​​

[0048] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0049] It should be noted that when an element is referred to as being "fixed to" another element, it can be directly attached to the other element or there may be an intervening element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or there may be an intervening element. The terms "vertical," "horizontal," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only possible implementation.

[0050] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0051] like Figures 1 to 11 The hydrostatic spindle structure with self-centering telescopic tip 4 shown includes an outer shell 1, a spindle 2, a support body 3, a telescopic tip 4, a limiting member 5, and a linear drive 6. The spindle 2 is coaxially disposed in the inner hole of the outer shell 1. The support body 3 supports and is used to realize the rotation of the spindle 2 relative to the outer shell 1. The telescopic tip 4 is disposed in the inner hole of the spindle 2, and a guide groove 4a is provided on the outer cylindrical surface of the telescopic tip 4. The limiting member 5 penetrates the side wall of the spindle 2 radially, and its end is embedded in the guide groove 4a, ensuring that the axial movement of the telescopic tip 4 can realize the synchronous rotation of the spindle 2 and the telescopic tip 4. The linear drive 6 is disposed at the rear end of the spindle 2, and its output end is connected to the telescopic tip 4 to drive the telescopic tip 4 to perform axial telescopic movements within the spindle 2.

[0052] The mandrel 2 has an axially oriented guide section 21 and a centering section 22. The inner wall of the centering section 22 converges inward toward the end face to form a guide cone surface. The telescopic tip 4 has a tip section 4b, a cone section 4c, and a sliding shaft section arranged sequentially from the front end to the rear end along the axial direction. The cone section 4c mates with the guide cone surface, and the outer cylindrical surface of the sliding shaft section has multiple sets of guide bands 411 arranged axially. The guide bands 411 slide with the inner wall of the guide section 21. It should be noted that the front end refers to the end of the telescopic tip 4 that abuts against the ball valve core; the rear end refers to the end of the telescopic tip 4 that is away from the ball valve core. Preferably, the linear drive 6 adopts a double-acting hydraulic cylinder, which includes a cylinder body and a piston rod. The cylinder body is connected to the mandrel 2, and the piston rod is connected to the telescopic tip 4, synchronously driving the telescopic tip 4 to move axially.

[0053] The present application ensures the initial coaxiality of the three by sequentially coaxially embedding the mandrel 2 and the telescopic center 4 into the inner hole of the outer shell 1; then embedding the stator part of the support body 3 into the inner hole of the outer shell 1, and fixing it by interference fit to ensure the coaxiality of the stator of the support body 3 and the outer shell 1; the middle part of the mandrel 2 is inserted into the inner hole of the rotor of the support body 3 at the area matched with the rotor, and is connected by transition fit to make the mandrel 2 rotate synchronously with the rotor of the support body 3 without jamming; the telescopic center 4 is slowly inserted into the rear end inner hole of the mandrel 2 until the tapered segment 4c of the telescopic center 4 is close to the centering segment 22 of the mandrel 2, the axial position of the telescopic center 4 is adjusted so that the guide groove 4a of the outer circle of the telescopic center 4 is aligned with the mounting hole of the side wall of the mandrel 2, three limiters 5 are installed along the circumferential direction of the mandrel 2, the limiters 5 are installed from the radial mounting hole outside the mandrel 2, and the end of the limiters 5 inserted into the inner hole of the mandrel 2 is completely embedded into the guide groove 4a, and the gap between the limiters 5 and the guide groove 4a meets the requirements of smooth axial sliding and no radial movement; the cylinder body of the linear driving member 6 is fixed on the rear end face of the mandrel 2 through a flange to ensure that the axis of the linear driving member 6 is collinear with the axis of the mandrel 2; the driving rod of the linear driving member 6 is connected with the rear end of the telescopic center 4 to ensure that the axis of the piston rod is coincident with the axis of the telescopic center 4; the mandrel 2 is started to rotate, the radial run-out of the telescopic center 4 is detected by the eddy current displacement sensor; the extension action of the center is simulated, the linear driving member 6 is controlled to push the telescopic center 4 to extend, the tapered segment 4c is completely matched with the guide cone surface, the coaxiality of the telescopic center 4 and the mandrel 2 is detected by the three-coordinate measuring instrument, and the coaxiality error is ensured to be within the set threshold range.

[0054] The present application forms a taper surface matching fit between the guide cone surface of the mandrel 2 and the tapered segment 4c of the telescopic center 4, when the telescopic center 4 is pushed out by the linear driving member 6, the tapered segment 4c slides along the guide cone surface, the axis deviation is automatically corrected by using the self-centering property of the taper surface, the axis of the telescopic center 4 is forced to coincide with the axis of the mandrel 2, and active centering is realized; a plurality of guide belts 411 are distributed along the axial direction, form a multi-point sliding support with the guide segment 21 of the inner hole of the mandrel 2, and disperse the gap between the telescopic center 4 and the mandrel 2 to a plurality of guide belts 411, when the telescopic center 4 rotates with the mandrel 2, a plurality of guide belts 411 provide radial support force from different axial positions, form an anti-deviation resultant force, avoid the deviation of the center to the outside of the gap pushed by the centrifugal force, effectively suppress the periodic radial run-out, ensure the roundness precision of the subsequent chuck clamping outer circle, improve the chuck clamping stability and positioning accuracy, and ensure the overall machining quality of the ball valve ball core.

[0055] In the preferred scheme of the present application, an auxiliary guide section 4d is further arranged between the tip section 4b and the taper section 4c; the diameter of the auxiliary guide section 4d is equal to the minimum diameter of the guide cone surface. When the telescopic center bit 4 is extended to the working position, the auxiliary guide section 4d passes through the centering section 22 of the mandrel 2 and forms a cylindrical surface fit with the small end of the guide cone surface, which can fill the radial gap in the transition area between the tip section 4b and the taper section 4c, so as to form a continuous support structure from the tip section 4b to the taper section 4c of the telescopic center bit 4, thereby solving the problem of radial runout in the transition area due to lack of support and improving the integrity of the axial support of the telescopic center bit 4; at the same time, the cylindrical surface fit of the auxiliary guide section 4d provides a pre-positioning function for the fitting of the taper section 4c and the guide cone surface. During the extension of the telescopic center bit 4, the auxiliary guide section 4d will first contact the small end of the guide cone surface, and the initial deviation of the center bit is limited in advance through the cylindrical surface fit, so as to ensure that the taper section 4c enters the fitting area of the guide cone surface in a more accurate posture, effectively reducing the lateral impact force generated by the initial deviation at the moment of cone surface fitting, reducing the risk of collision between the taper section 4c and the guide cone surface, reducing the wear of the fitting surface during long-term use, and prolonging the service life of the components.

[0056] In the present application, the telescopic center bit 4 is provided with at least two groups of guide bands 411 in the axial direction; one group of guide bands 411 is arranged at the position close to the taper section 4c of the telescopic center bit 4, and the other group is arranged at the position close to the oil cylinder; and the guide groove 4a is located between the two groups of guide bands 411.

[0057] The two groups of guide bands 411 are arranged at the positions of the two ends of the telescopic center bit 4 in contact with the inner hole of the mandrel 2, specifically, the group of guide bands 411 close to the taper section 4c can form a close sliding fit with the guide section 21 of the inner hole of the mandrel 2, forming a first radial constraint at the position close to the front end of the telescopic center bit 4, which can directly limit the radial swing of the tip section 4b due to the centrifugal force when the telescopic center bit 4 rotates at high speed with the mandrel 2, thereby avoiding the deviation of the front end positioning reference; and the other group of guide bands 411 close to the linear driving member 6 forms a second radial constraint at the position close to the rear end driving member of the telescopic center bit 4, which can accurately control the direction of the axial driving force applied to the telescopic center bit 4 by the linear driving member 6, prevent the driving force from causing unilateral stress on the center bit due to unbalanced load, and form a force balance system with the front end guide band 411, thereby effectively offsetting the asymmetric force at the two ends of the telescopic center bit 4 in the axial direction and avoiding the attitude deformation problem of unilateral deviation and unilateral inclination of the whole body in the axial direction.

[0058] The axial two-end positioning support structure constructed by the two groups of guide belts 411 can disperse the fitting gap between the telescopic center 4 and the inner hole of the mandrel 2, and limit the gap within the small contact range of the two-end guide belts 411, greatly reduce the radial movement space of the center, and block the path of the centrifugal force driving the center to deviate to the outside of the gap from the structure, thereby significantly reducing the periodic fluctuation amplitude of the coaxiality, effectively avoiding the corrugation defects caused by the positioning deviation during the outer circle grinding of the ball core clamping, and providing a high-precision outer circle reference for the subsequent chuck clamping.

[0059] In the preferred embodiment of the present application, one group of guide belts 411 includes at least two guide rings 411a arranged at intervals along the axial direction; the outer circular surface of the telescopic center 4 is provided with a ring groove, and the guide ring 411a is embedded in the ring groove, and the outer circular surface protruding from the ring groove is in sliding contact with the inner hole wall of the mandrel 2.

[0060] The guide belt 411 is arranged in sliding contact with the inner hole wall of the mandrel 2 by the guide ring 411a, and radial positioning is achieved, and the design of the two narrow surfaces of the guide ring 411a can indirectly improve the fitting accuracy of the guide belt 411 and the inner hole of the mandrel 2, and the guide ring is made of phenolic cloth material to avoid hard contact between the guide ring 411a and the inner hole wall of the mandrel 2, which not only ensures the guiding accuracy, but also prevents wear caused by moving jamming, effectively improving the stability and service life of the overall structure of the telescopic center 4.

[0061] On the basis of the above-mentioned scheme, the guide ring 411a is provided with a notch in the circumferential direction; when the linear driving member 6 pushes the telescopic center 4 to extend to the working position, the tapered section 4c of the telescopic center 4 will be closely fitted with the guide tapered surface of the centering section 22 of the mandrel 2, at this time, the stepped stepped shaft outer cylindrical surface between the tapered section 4c and the guide ring 411a forms an annular gap with the inner hole wall of the mandrel 2, and the setting of the notch can make the air in the annular gap flow along the axial direction of the telescopic center 4, avoid air stagnation resistance, ensure smooth retraction of the telescopic center 4, and there is no delay or jamming phenomenon, which improves the response speed of the telescopic center 4.

[0062] In the present application, in the static state, the guide belt 411 and the inner hole of the mandrel 2, the limiting member 5 and the guide groove 4a between them exist static friction, and the oil pressure needs to overcome the static friction before driving the center to move, which causes the response delay of the oil pressure starting but the center not moving; therefore, in order to ensure that the telescopic center 4 can respond in time, preferably, the telescopic center 4 includes a first shaft section 41, a second shaft section 42 and a guide shaft section 43, the first shaft section 41 and the second shaft section 42 are connected in the threaded hole of the guide shaft section 43 through the screw connection of the end part; the guide groove 4a is uniformly arranged on the outer cylindrical surface of the guide shaft section 43 in the circumferential direction and is arranged in the axial direction; at least one group of guide belts 411 is arranged on the first shaft section 41 and the second shaft section 42.

[0063] The elastic member 44 is arranged between the guide shaft section 43 and the stepped surface of the first shaft section 41 and the second shaft section 42, and the moving stroke of the limiting member 5 along the guide groove 4a is greater than the axial length of the guide shaft section 43. It should be noted that when the mandrel 2 drives the telescopic center 4 to rotate synchronously, the torque transmission needs to rely on the limiting member 5, so in the assembly stage, the screwing of the first shaft section 41, the second shaft section 42 and the guide shaft section 43 adopts a locking tightening process. According to the rotation direction of the main shaft, the screwing tightening direction is set to be consistent with the driving torque direction of the limiting member 5; when the limiting member 5 drives the guide shaft section 43 to rotate, the transmitted torque will further compact the thread engagement surface, rather than generate a reverse loosening torque, thereby eliminating the possibility of screw loosening from the stress direction.

[0064] The elastic member 44 arranged between the guide shaft section 43 and the stepped surface of the first shaft section 41 and the second shaft section 42 is in a pre-compressed state during assembly, which will exert a continuous axial pre-tightening force on the first shaft section 41 and the second shaft section 42. The pre-tightening force offsets the static friction in advance; when the linear drive 6 starts, only the remaining friction needs to be overcome to push the center to move, thereby shortening the response delay. At the same time, the pre-tightening force of the elastic member 44 can be released with the driving action, forming an auxiliary thrust force to further accelerate the starting speed.

[0065] During the valve core processing process, the linear drive 6 pushes the center to tightly push the ball core, which will generate an axial impact; the elastic member 44 can absorb the impact energy through deformation to avoid the impact being directly transmitted to the screw thread or the guide belt 411, thereby preventing thread slipping, guide belt 411 cracking and other faults; the instantaneous change of centrifugal force during the rotation start and stop of the mandrel 2 will also generate an axial impact, and the elastic member 44 can act as a buffer pad to maintain the stability of the shaft section and avoid radial runout fluctuations caused by impact.

[0066] As a preferred embodiment of the above embodiment, the axial length of the guide shaft section 43 is greater than the sum of the threaded shaft section lengths of the first shaft section 41 and the second shaft section 42. When the first shaft section 41 and the second shaft section 42 are rotated to screw into the guide shaft section 43 inside the threaded hole, the stepped surface of the shaft section will move towards the elastic member 44, extruding the elastic member 44 to generate compression deformation. The greater the screwing-in depth, the greater the compression of the elastic member 44, and the stronger the initial pre-tightening force. Conversely, when the shaft sections are unscrewed, the compression of the elastic member 44 decreases, and the pre-tightening force weakens. Specifically, the first shaft section 41 is a front-end positioning section, and the pre-tightening force of the elastic member 44 on one side of the first shaft section 41 is increased separately to enhance the front-end starting assistance, quickly break through the static friction force between the front-end guide belt 411 and the inner hole of the mandrel 2, and ensure the instantaneous start of the extension action, while avoiding overextension due to excessive rear-end assistance. The second shaft section 42 is a rear-end driving section, and the pre-tightening force of the elastic member 44 on one side of the second shaft section 42 is increased separately to enhance the rear-end starting assistance, quickly break through the static friction force of the rear-end guide belt 411, and ensure smooth retraction, while avoiding retraction jamming and preventing the ball core from deviating during retraction due to excessive front-end assistance. By separately adjusting the pre-tightening forces on both sides, the starting assistance for extension or retraction can be precisely controlled without the need for overall adjustment, greatly improving the precision of starting assistance control.

[0067] In a preferred embodiment of the present application, the elastic member 44 includes a disc spring set 441 and a ring pressing plate 442; the limiting member 5 slides in the guide groove 4a and drives the ring pressing plate 442 to move towards the stepped surface, compressing the disc spring set 441.

[0068] The disc spring set 441 is formed by reversing and stacking multiple disc springs, and the ring pressing plate 442 serves as an intermediate force transmission. The ring pressing plate 442 uniformly distributes the point load from the limiting member 5 to the annular end face of the ring pressing plate 442, and then transmits the surface load to the disc spring set 441, so that the stress distribution difference of the stress surface of the disc spring set 441 is controlled within a predetermined range, avoiding the risk of local crushing of the edge of the disc spring due to stress overload. At the same time, the uniform transmission of surface load ensures that the compression amount of each piece of the disc spring set 441 is consistent, effectively controlling the stability of the pre-tightening force output and avoiding fluctuations in the pre-tightening force due to uneven local compression.

[0069] The outer circle of the ring pressing plate 442 is in clearance fit with the inner hole of the mandrel 2, which not only ensures smooth movement of the ring pressing plate 442 along the axial direction, but also limits its radial movement. When the limiting member 5 drives the ring pressing plate 442 to move axially, the ring pressing plate 442 can accurately guide the reversed and stacked disc spring set 441 to compress along the axis of the extension top 4, avoiding the problem of skewed compression of the disc spring set 441 due to radial deviation, preventing jamming or wear between the pieces of the disc spring set 441 due to misalignment, and ensuring that the transmission of the pre-tightening force from the ring pressing plate 442 to the disc spring set 441 always remains linear, thereby guaranteeing the linearity of the pre-tightening force transmission.

[0070] According to the static friction force of the matching surface between the telescopic center 4 and the mandrel 2, the compression amount of the elastic member 44 is adjusted, the pre-tightening force of the disc spring set 441 is further adjusted by adjusting the compression amount, the disc spring set 441 always applies a stable axial pushing force to the limiting member 5, the pushing force can offset part of the static friction force in advance, and when the telescopic center is retracted by oil pressure, only a small oil pressure is needed to overcome the remaining friction force; at the same time, the pre-tightening force release of the disc spring set 441 is synchronous with the driving force of the linear driving member 6, the response time from oil pressure starting to the action of the telescopic center is shortened, the starting process is ensured to be free of vibration, and the action of the telescopic center 4 is ensured to be stable.

[0071] In the preferred embodiment, the outer edge of the disc spring set 441 is in abutting cooperation with the outer edge of the ring pressing plate 442; the limiting member 5 is embedded in the end of the guide groove 4a and abuts at the position of the outer edge of the ring pressing plate 442, and the plurality of limiting members 5 distributed along the circumference abut at the end of the outer edge of the ring pressing plate 442 to jointly form a force applying ring surface.

[0072] The disc spring set 441 is reversely stacked, the gravity center of force is biased to the outer edge, the outer edge of the disc spring set 441 abuts the outer edge of the ring pressing plate 442, the force applying ring surface of the disc spring set 441 is coaxial and coincides with the force applying ring surface formed by the limiting member 5; when the limiting member 5 drives the ring pressing plate 442 to move axially, the ring pressing plate 442 directly transmits the driving force to the outer edge area of the disc spring set 441 through the outer edge, thereby pushing the disc spring set 441 to move synchronously, the outer edge transmission structure can avoid the moment imbalance of the ring pressing plate 442 caused by the force applying point on the inner side and the force receiving point on the outer side, eliminate the bending deformation risk of the ring pressing plate 442 caused by the eccentric load, and ensure that the ring pressing plate 442 always maintains a plane state to transmit force; in addition, the abutting cooperation between the outer edge of the ring pressing plate 442 and the outer edge of the disc spring set 441 forms a flexible buffer interface, when the main shaft rotates to generate vibration, the interface can absorb part of the vibration energy, effectively block the transmission of vibration to the centering section 22 of the telescopic center 4, avoid the slight deviation of the centering section 22 caused by vibration, further improve the stability of ball core positioning, finally reduce the waviness defects caused by positioning fluctuation in ball core outer circle grinding processing, and ensure the processing precision.

[0073] In the preferred embodiment of the application, the support body 3 includes a front bearing set 31 and a rear bearing set 32; the front bearing set 31 is arranged at the front end of the mandrel 2, the rear bearing set 32 is arranged at the rear end of the mandrel 2, and a thrust ring is arranged at the end of the front bearing set 31 close to the rear bearing set 32.

[0074] The front bearing group 31 is close to the centering section 22 of the telescopic center 4, and the rear bearing group 32 is close to the linear driving member 6. The two bearing groups form a reasonable support span along the axis of the mandrel 2 in the axial direction, and can effectively disperse the radial bending moment of the mandrel 2. When the liquid static pressure spindle rotates at high speed, the two bearing groups can synchronously limit the radial degree of freedom of the mandrel 2 from the front and rear ends, control the radial runout amount of the mandrel 2 when rotating, and at the same time, the cooperative support of the two bearing groups can offset the imbalance of the centrifugal force when rotating, avoid high-frequency radial vibration caused by the centrifugal force, and ensure the centering accuracy of the telescopic center 4 when rotating synchronously with the mandrel 2.

[0075] Those skilled in the art should understand that the present application is not limited to the above-mentioned embodiments, and the above-mentioned embodiments and descriptions in the specification are only to illustrate the principles of the present application. Without departing from the spirit and scope of the present application, various changes and improvements can be made to the present application, and these changes and improvements all fall within the scope of the present application. The scope of protection of the present application is defined by the appended claims and their equivalents.

Claims

1. A hydrostatic spindle structure with self-centering telescopic tailstock, characterized in that, The utility model relates to a kind of telescopic centering devices, including: Outer shell; Core shaft, coaxial setting in the inner hole of the outer shell, limit piece is arranged on its side wall along radial direction; Supporting body, supporting and being used to realize the rotation of the core shaft relative to the outer shell; Telescopic center, setting in the inner hole of the core shaft, it has guiding groove on outer cylindrical surface, accommodating the end of the limit piece; Linear drive, setting in the rear end of the core shaft, for driving the telescopic center to do axial telescopic action in the core shaft; Wherein, the inner hole of the core shaft is provided with guiding section and centering section along axial direction, the inner hole wall of the centering section is inwardly converged towards end surface, forms guiding cone surface; The telescopic center is sequentially provided with center segment, cone segment and sliding shaft segment from front end to rear end along axial direction; The cone segment cooperates with the guiding cone surface, the outer cylindrical surface of the sliding shaft segment is provided with multiple groups of guiding belts along axial direction, and the guiding belts are slidably connected with the inner hole wall of the guiding section; Auxiliary guiding section is further arranged between the center segment and the cone segment; The diameter of the auxiliary guiding section is equal to the minimum diameter of the guiding cone surface; The telescopic center is provided with at least two groups of guiding belts along axial direction; One group of the guiding belts is arranged at the position close to the cone segment of the telescopic center, and the other group is arranged at the position close to the linear drive of the telescopic center; And the guiding groove is located between the two groups of guiding belts; One group of the guiding belts includes at least two guiding rings arranged along axial direction; The outer circular surface of the telescopic center is provided with ring groove, the guiding ring is embedded in the ring groove, and the outer circular surface protruding from the ring groove is in sliding contact with the inner hole wall of the core shaft.

2. The structure of the liquid dynamic pressure spindle with self-centering telescopic tailstock according to claim 1, characterized in that, The guiding ring is provided with a notch in the circumferential direction.

3. The structure of the liquid dynamic pressure spindle with self-centering telescopic tailstock according to claim 1, characterized in that, The telescopic center includes a first shaft segment, a second shaft segment, and a guide shaft segment. The first shaft segment and the second shaft segment are connected in the threaded hole of the guide shaft segment through the threaded shaft segments at the ends. The guiding grooves are uniformly distributed on the outer cylindrical surface of the guide shaft segment in the circumferential direction and are arranged through in the axial direction. At least one group of guiding belts is arranged on the first shaft segment and the second shaft segment. The guiding shaft segment and the step surface between the first shaft segment and the second shaft segment are both provided with elastic members, and the movement stroke of the limit piece along the guiding groove is greater than the axial length of the guiding shaft segment.

4. The structure of the liquid dynamic pressure spindle with self-centering telescopic tailstock according to claim 3, characterized in that, The axial length of the guiding shaft segment is greater than the sum of the threaded shaft segment lengths of the first shaft segment and the second shaft segment.

5. The structure of the liquid dynamic pressure spindle with self-centering telescopic tailstock according to claim 3, characterized in that, The elastic members include a disc spring group and a ring pressing plate. The limit piece slides in the guiding groove and drives the ring pressing plate to move towards the step surface, compressing the disc spring group.

6. The hydrostatic spindle structure with self-centering telescopic tailstock according to claim 5, characterized in that, The outer edge of the disc spring group is in abutting contact with the outer edge of the ring pressing plate. The limit piece is embedded in the end of the guiding groove and abuts against the outer edge position of the ring pressing plate. Multiple limit pieces distributed in the circumferential direction abut against the end of the outer edge of the ring pressing plate to collectively form a force ring surface.

7. The structure of the liquid dynamic pressure spindle with self-centering telescopic tailstock according to claim 1, characterized in that, The supporting body includes a front bearing group and a rear bearing group. The front bearing group is arranged at the front end of the core shaft, the rear bearing group is arranged at the rear end of the core shaft, and a thrust ring is arranged at one end of the front bearing group close to the rear bearing group.

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