A backlash-free transmission structure for machine tools

Abstract

This invention belongs to the field of machine tool transmission technology, and particularly relates to a backlash-free transmission structure for machine tools. The invention provides a backlash-free transmission structure for machine tools, including a gearbox, a transmission wheel assembly, and a backlash-free assembly. The backlash-free assembly includes a composite damping component, a tightening disc, and a damping adjustment component. This invention combines the advantages of elastic backlash elimination and rigid transmission. Within the tooth backlash range, it exhibits low-stiffness elastic backlash elimination, ensuring no rigid hard impact on the tooth surface. Under acceleration / heavy cutting conditions, it exhibits high-stiffness transmission, ensuring the trajectory accuracy and dynamic response of the cutting bed. Simultaneously, it possesses damping energy absorption functionality, effectively solving problems such as response lag and fatigue failure in existing technologies.

Description

Technical Field

[0001] This invention belongs to the field of machine tool transmission technology, and particularly relates to a backlash-free transmission structure for machine tools. Background Technology

[0002] In the application of the transmission structure of a cutting machine, since the cutter head needs to frequently turn to cut different shapes of contours, the transmission chain needs to change direction quickly. If the preload is too small, the gap cannot be effectively eliminated, resulting in lag in reversal. If the preload is too large, it will increase tooth surface wear and energy loss. Furthermore, when the cutting machine cuts the same material in different directions or different materials, the resistance experienced by the cutter head varies greatly.

[0003] To address the backlash issues caused by gear transmissions, various backlash-eliminating transmission structures have emerged in existing technologies. Among these, the double-gear backlash-eliminating structure is a commonly used solution. This structure employs two pinions simultaneously meshing with the same rack. One pinion meshes with the forward-facing tooth surface of the rack, while the other meshes with the reverse-facing tooth surface. A preload device applies a relative torsional torque between the two pinions, causing them to press against the two tooth surfaces of the rack, thereby eliminating backlash. However, common preload devices suffer from constant stiffness, making them unsuitable for various operating conditions.

[0004] Therefore, the existing technology still has at least the following shortcomings in actual use, which are the problems that this invention aims to solve: 1. The constant preload of the traditional backlash elimination structure cannot be dynamically adjusted according to the working conditions, resulting in poor backlash elimination effect in situations requiring rapid response; 2. Traditional spring steel torsion bars will develop fatigue cracks after being subjected to high-frequency alternating stress for a long time.

[0005] In conclusion, it is necessary to develop a backlash-free transmission structure that can adapt to the changing working conditions of the cutting bed to solve this problem. Summary of the Invention

[0006] This invention provides a backlash-free transmission structure for machine tools, including a gearbox, a transmission wheel assembly, and a backlash-free assembly. The backlash-free assembly includes a composite damping component, a tightening disc, and a damping adjustment component. This invention combines the advantages of elastic backlash elimination and rigid transmission. Within the tooth backlash range, it exhibits low-stiffness elastic backlash elimination, ensuring that the tooth surface does not experience rigid hard collisions. Under acceleration / heavy cutting conditions, it exhibits high-stiffness transmission, ensuring the trajectory accuracy and dynamic response of the cutting bed. It also has a damping energy absorption function, effectively solving the problems of response lag and fatigue failure in existing technologies.

[0007] This invention overcomes the shortcomings of existing technologies and provides a backlash-free transmission structure for machine tools, including a gearbox housing, a transmission wheel assembly and a backlash-free assembly disposed within the gearbox housing; the transmission wheel assembly includes a drive wheel, a first large gear and a second large gear meshing with both sides of the drive wheel respectively, and a first small gear and a second small gear meshing with both sides of a rack respectively; the first large gear and the first small gear are coaxially arranged, and the second large gear is mounted on the same central axis as the second small gear via a bearing; the backlash-free assembly includes a composite damping element disposed on the upper end of the second large gear, and a tightening disc disposed on the upper end of the composite damping element; the composite damping element includes a... The upper end of the central shaft has an elastic inner rod, a rigid outer tube sleeved outside the elastic inner rod and connected to the tightening disc at its top end, a flange located at the lower end of the rigid outer tube and bolted to the upper end of the second large gear, a limiting spline located on the outer wall of the central shaft above the second large gear, and a limiting spline groove located on the inner wall of the rigid outer tube and cooperating with the limiting spline. A closed annular cavity is formed between the outer wall of the elastic inner rod and the inner wall of the rigid outer tube. The annular cavity is filled with a damping layer. A micro gap is reserved between the limiting spline groove and the limiting spline. The top end of the elastic inner rod is connected to the middle of the tightening disc through a tight-fitting spline.

[0008] A further preferred technical solution is that the composite damping component further includes a moving blade disposed on the elastic inner rod and extending toward the rigid outer tube, and a fixed blade disposed on the inner wall of the rigid outer tube and extending toward the elastic inner rod, wherein the moving blade and the fixed blade divide the annular cavity into multiple hydraulic chambers.

[0009] A further preferred technical solution is that: the backlash elimination assembly further includes a first damping adjustment component disposed on the composite damping component for adjusting the flow resistance; the first damping adjustment component includes a radial flow channel disposed on the fixed blade for connecting two adjacent hydraulic chambers, a vertical oil passage disposed in the thickness direction of the fixed blade and extending from the top of the fixed blade to the radial flow channel, and a first adjusting needle valve passing through the tightening disc and extending into the vertical oil passage, the lower end of the first adjusting needle valve having a taper.

[0010] A further preferred technical solution is that: the backlash elimination assembly further includes a second damping adjustment component disposed on the tightening disc for adjusting flow resistance; the second damping adjustment component includes an inner ring groove and an outer ring groove concentrically disposed inside the tightening disc, a plurality of first through holes disposed on the lower surface of the tightening disc and located above the even-numbered hydraulic chambers and communicating with the inner ring groove, a plurality of second through holes disposed on the lower surface of the tightening disc and located above the odd-numbered hydraulic chambers and communicating with the outer ring groove, a three-way channel disposed between the inner ring groove and the outer ring groove and extending upward, and a second adjusting needle valve disposed within the three-way channel, the lower end of the second adjusting needle valve having a taper.

[0011] A further preferred technical solution is that the elastic inner rod is a solid column made of spring steel, and its lower end is interference-fitted with the central shaft.

[0012] A further preferred technical solution is that the arc length of the micro-gap in the circumferential direction is equal to the maximum meshing gap accumulated by the gap elimination component.

[0013] A further preferred technical solution is that the composite damping component further includes a sealing ring disposed on the outer wall of the central shaft and located below the limiting spline groove.

[0014] A further preferred technical solution is that the damping layer is dimethyl silicone oil or phenyl silicone oil.

[0015] The beneficial effects of this invention are at least as follows: 1. It combines the advantages of elastic backlash elimination and rigid transmission. Within the tooth backlash range, the system exhibits a low-stiffness elastic backlash elimination state. The elastic deformation of the elastic inner rod can effectively absorb gear backlash, ensuring that the tooth surface does not experience rigid hard collisions. During acceleration or heavy cutting, when the load exceeds the set threshold, the limit spline engages, and the system switches to a high-stiffness transmission state, ensuring the trajectory accuracy and dynamic response of the machine tool, thus solving the problem of constant stiffness in traditional technologies; 2. It transforms the traditional pure mechanical spring energy storage mechanism into a damping energy dissipation mechanism. When the system is subjected to high-frequency pulse impact, the viscous fluid converts the mechanical vibration energy into heat energy through shearing action and dissipates it rapidly, effectively absorbing the high-frequency pulse reaction force of the machine tool head, protecting the components, and significantly extending the service life; 3. The damping magnitude can be adjusted according to different working conditions. Attached Figure Description

[0016] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1This is a front sectional view of the present invention; Figure 2 This is a side sectional view of the blade in Embodiment 2 of the present invention. Figure 1 ; Figure 3 This is a side sectional view of the blade in Embodiment 2 of the present invention. Figure 2 ; Figure 4 This is a top view of Embodiment 3 of the present invention; Figure 5 This is a top view of the present invention; Figure 6 This is a three-dimensional schematic diagram of the present invention; Figure 7 This is a front view of the present invention.

[0018] The meanings of the various reference numerals in the figure are as follows: Gearbox housing 1, transmission wheel assembly 2, backlash elimination assembly 3; Drive wheel 21, first large gear 22, second large gear 23, first small gear 24, second small gear 25, bearing 26, central shaft 27, composite damping component 31, tightening disc 32, first damping adjustment component 33, second damping adjustment component 34; Elastic inner rod 311, rigid outer tube 312, flange 313, limiting spline 314, limiting spline groove 315, annular cavity 316, tight-fitting spline 317, moving blade 318, fixed blade 319, sealing ring 320, radial flow channel 331, vertical oil passage 332, first regulating needle valve 333, inner annular groove 341, outer annular groove 342, first through hole 343, second through hole 344, three-way channel 345, second regulating needle valve 346. Detailed Implementation

[0019] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings. The following description is only a preferred embodiment of the present invention and is not intended to limit the scope of the present invention.

[0020] The directional terms such as up, down, left, right, front, back, front, back, top, bottom, etc., mentioned or possibly mentioned in this specification are defined relative to the structure shown in the accompanying drawings. The terms "inner" and "outer" refer to the direction toward or away from the geometric center of a specific component, respectively. These are relative concepts and may therefore vary depending on their location and usage. Therefore, these or other directional terms should not be interpreted as restrictive terms.

[0021] Example 1 As attached Figure 1 Appendix Figures 5-7As shown, a backlash-free transmission structure for a machine tool includes a gearbox 1, a transmission wheel assembly 2 and a backlash-free assembly 3 disposed within the gearbox 1; the transmission wheel assembly 2 includes a drive wheel 21, a first large gear 22 and a second large gear 23 respectively meshing with both sides of the drive wheel 21, a first small gear 24 and a second small gear 25 respectively meshing with both sides of the rack tooth surface, the first large gear 22 and the first small gear 24 being coaxially arranged, and the second large gear 23 being disposed on the same central shaft 27 with the second small gear 25 via a bearing 26; the backlash-free assembly 3 includes a composite damping element 31 disposed on the upper end of the second large gear 23, and a tightening disc 32 disposed on the upper end of the composite damping element 31; the composite damping element 31 includes an elastic inner rod 311 disposed on the upper end of the central shaft 27, and a sleeved outer portion of the elastic inner rod 311 with its top end connected to the inner rod. The tightening disc 32 is connected to a rigid outer tube 312, a flange 313 is bolted to the lower end of the rigid outer tube 312 and to the upper end of the second large gear 23, a limiting spline 314 is located on the outer wall of the central shaft 27 and above the second large gear 23, a limiting spline groove 315 is located on the inner wall of the rigid outer tube 312 and mates with the limiting spline 314, a sealing ring 320 is located on the outer wall of the central shaft 27 and below the limiting spline groove 315, a sealed annular cavity 316 is formed between the outer wall of the elastic inner rod 311 and the inner wall of the rigid outer tube 312, the annular cavity 316 is filled with a damping layer, a micro gap is reserved between the limiting spline groove 315 and the limiting spline 314, and the top end of the elastic inner rod 311 is connected to the middle of the tightening disc 32 through a tight-fitting spline 317.

[0022] In this embodiment, the transmission wheel assembly includes a first large gear, a first small gear, a second large gear, a second small gear, a drive wheel, and a rack. The rack is fixedly connected to the machine tool component to be reciprocated, such as the cutting head component of a cutting bed. The second large gear is mounted on a central shaft via bearings, allowing the second large gear to rotate relative to the second central shaft. The tooth surface of the first small gear meshes with the tooth surface of the rack in a forward direction, and the tooth surface of the second small gear meshes with the other tooth surface of the rack in a reverse direction. The drive wheel meshes with the first large gear and the second large gear on both sides, respectively. The drive wheel is driven by an external servo motor gear.

[0023] The backlash elimination assembly 3 includes a composite damping element 31 and a tightening disc 32. The composite damping element 31 is the core component of this invention, mainly comprising an elastic inner rod, a rigid outer tube, and a viscous damping layer filled in the annular cavity between the elastic inner rod and the rigid outer tube. The rigid outer tube is made of high-strength alloy steel, preferably 40CrNiMoA alloy structural steel, with a tensile strength of not less than 980MPa after quenching and tempering. The elastic inner rod is made of spring steel. The lower end of the elastic inner rod is interference-fitted with the upper end of the central shaft, with an interference of 0.02mm to 0.05mm. The top of the elastic inner rod is provided with a tight-fit spline, which is in close fit with the tight-fit spline groove of the tightening disc. The lower end of the rigid outer tube is provided with a flange, which is connected to the upper surface of the second large gear by bolts. The upper end of the rigid outer tube is connected to the tightening disc by a positioning bolt. The rod body of the central shaft is provided with a limit spline near the upper part, which is evenly distributed along the circumference and is designed with a buffer gasket. The damping layer in the annular cavity is a viscous fluid, and the filling amount is 95~98% of the volume of the annular cavity, with 2~5% space reserved for thermal expansion.

[0024] A sealing ring groove is provided on the inner wall of the central shaft below the limiting spline groove. The sealing ring is installed in the sealing ring groove and is preferably a fluororubber O-ring or Step seal with a temperature resistance range of -20°C to 200°C. The lower end of the rigid outer tube presses against the sealing ring.

[0025] The working principle of this embodiment is as follows: Under normal operating conditions, when the torque generated by the external load is less than the maximum elastic torque of the elastic inner rod within the micro-clearance range, the system is in a flexible backlash-free state. At this time, the power transmission path is: second large gear → flange → rigid outer tube → damping layer → elastic inner rod → central shaft → second small gear. The elastic inner rod undergoes elastic torsion, with a torsion angle less than half the micro-clearance. The limiting spline and limiting spline groove do not contact each other. The elastic deformation of the elastic inner rod effectively absorbs gear backlash, providing a flexible backlash-free function. When the external load increases, causing the torsion angle of the elastic inner rod to reach the limit value of the micro-clearance, the limiting spline and limiting spline groove tooth surfaces come into contact. At this time, the power transmission path becomes: second large gear → flange → rigid outer tube → limiting spline groove → limiting spline → elastic inner rod → second central shaft → second small gear. The rigid outer tube directly participates in power transmission, significantly improving the system's equivalent torsional stiffness.

[0026] Under high-frequency impact conditions, when the second pinion is subjected to a high-frequency pulse impact, the elastic inner rod generates high-frequency micro-torsional vibrations. Due to the presence of the damping layer, when the elastic inner rod and the rigid outer tube undergo relative angular displacement, the viscous fluid is sheared, generating a damping torque. The damping torque is proportional to the relative shear velocity; the higher the frequency, the greater the damping torque. This viscous damping effect converts vibration energy into heat energy and dissipates it rapidly, effectively reducing the amplitude of alternating stress borne by the elastic inner rod.

[0027] As a preferred embodiment, the elastic inner rod 311 is a solid column made of spring steel, and its lower end is interference-fitted with the central shaft 27.

[0028] In this embodiment, 60Si2Mn alloy spring steel is specifically selected, and the fatigue limit of the spring steel is not less than 600MPa.

[0029] As a preferred embodiment, the arc length of the micro-gap in the circumferential direction is equal to the maximum meshing gap accumulated by the gap-eliminating component 3.

[0030] In this embodiment, the central angle corresponding to the micro-gap is 0.5~3°. The micro-gap is the accumulation of gear pair backlash, bearing clearance and shaft elastic deformation. The gear pair backlash is the cumulative angle of all gear pair backlashes calculated at the central axis, the bearing clearance is the cumulative angle of all bearing clearances calculated at the central axis, and the shaft elastic deformation is the elastic deformation angle of the shaft under rated torque.

[0031] As a preferred embodiment, the damping layer is dimethyl silicone oil or phenyl silicone oil.

[0032] In this embodiment, if the ambient temperature varies greatly, phenyl silicone oil can be used to avoid the silicone oil viscosity being affected by temperature, or a 10% damping margin can be reserved.

[0033] As a preferred embodiment, the composite damping member 31 further includes a moving blade 318 disposed on the elastic inner rod 311 and extending toward the rigid outer tube 312, and a fixed blade 319 disposed on the inner wall of the rigid outer tube 312 and extending toward the elastic inner rod 311. The moving blade 318 and the fixed blade 319 divide the annular cavity 316 into multiple hydraulic chambers.

[0034] In this embodiment, the inner wall of the rigid outer tube is provided with inwardly protruding fixed blades, and the outer wall of the elastic inner rod is provided with outwardly protruding moving blades. There are four fixed blades and four moving blades, which are evenly distributed along the circumference. The fixed blades and moving blades are arranged alternately to divide the annular cavity into eight independent fan-shaped hydraulic cavities.

[0035] Example 2 As attached Figures 2-3As shown, as a further improvement of the above embodiment, the backlash elimination component 3 further includes a first damping adjustment component 33 disposed on the composite damping component 31 for adjusting the flow resistance; the first damping adjustment component 33 includes a radial flow channel 331 disposed on the fixed blade 319 for connecting two adjacent hydraulic chambers, a vertical oil passage 332 disposed in the thickness direction of the fixed blade 319 and extending from the top of the fixed blade 319 to the radial flow channel 331, and a first adjusting needle valve 333 passing through the tightening disc 32 and extending into the vertical oil passage 332, the lower end of the first adjusting needle valve 333 having a taper.

[0036] In this embodiment, adjacent hydraulic chambers are connected by radial flow channels. These radial flow channels are located inside the fixed blade and include a main flow channel, a radial inlet hole, and a radial outlet hole. The radial inlet hole connects the vertical oil passage to the first hydraulic chamber, and the radial outlet hole connects the vertical oil passage to the adjacent second hydraulic chamber. The vertical oil passage runs along the thickness direction of the fixed blade, and the main flow channel is preferably L-shaped. A first adjusting needle valve is screwed vertically into the fixed blade from directly above, with a taper of at least 60° at its lower end. It is inserted into the vertical oil passage via a threaded connection, and the threaded section is equipped with a sealing ring. A locking nut is provided at the exposed top of the first adjusting needle valve. By changing the insertion depth of the adjusting needle valve, the effective flow area of ​​the vertical oil passage can be changed, thereby adjusting the fluid flow resistance.

[0037] The working principle of this embodiment is as follows: When the elastic inner rod rotates clockwise relative to the rigid outer tube, the moving blade compresses the even-numbered hydraulic chambers, pressurizing the silicone oil inside. Due to the obstruction of the fixed blade, the silicone oil cannot flow directly through adjacent chambers but can only flow through the radial flow channel. The silicone oil flows out from the pressurized chamber, enters the vertical oil channel through the radial oil inlet, flows through the throttling orifice of the first adjusting needle valve, and then flows into the expanding odd-numbered hydraulic chambers through the radial oil outlet. When the first adjusting needle valve is fully turned out, the throttling orifice area is the largest, the flow resistance is the smallest, and the damping coefficient is the smallest. When the first adjusting needle valve is gradually turned in, the throttling orifice area decreases, the flow resistance increases, and the damping coefficient increases. By adjusting the first adjusting needle valve, the damping coefficient can be continuously adjusted.

[0038] The beneficial effects of this embodiment are as follows: The blade structure increases the damping coefficient of pure interstitial flow, which can effectively absorb high-frequency vibrations. By adjusting the first regulating needle valve, the damping magnitude can be adjusted according to the actual working conditions. When cutting soft materials, the needle valve opening is adjusted to 70% to 80% to maintain low damping and improve the system response speed. When cutting hard materials, the needle valve opening is adjusted to 20% to 30% to provide higher damping and effectively absorb impacts.

[0039] Example 3 As attached Figure 4As shown, as a further improvement of the above embodiment, the backlash elimination assembly 3 further includes a second damping adjustment member 34 disposed on the tightening disc 32 for adjusting the flow resistance; the second damping adjustment member 34 includes an inner ring groove 341 and an outer ring groove 342 concentrically disposed inside the tightening disc 32, a plurality of first through holes 343 disposed on the lower surface of the tightening disc 32, located above the even-numbered hydraulic chambers and communicating with the inner ring groove 341, a plurality of second through holes 344 disposed on the lower surface of the tightening disc 32, located above the odd-numbered hydraulic chambers and communicating with the outer ring groove 342, a three-way channel 345 disposed between the inner ring groove 341 and the outer ring groove 342 and extending upward, and a second adjusting needle valve 346 disposed in the three-way channel 345, the lower end of the second adjusting needle valve 346 having a taper.

[0040] In this embodiment, a concentric annular oil groove design is adopted to achieve pressure equalization and single-needle valve regulation. The tightening disc has two sets of through holes: a first through hole and a second through hole. The first through hole includes four holes, each corresponding to the top of all even-numbered hydraulic chambers, connecting all even-numbered hydraulic chambers to the inner annular groove. The second through hole also includes four holes, each corresponding to the top of all odd-numbered hydraulic chambers, connecting all odd-numbered hydraulic chambers to the outer annular groove. In this way, all even-numbered hydraulic chambers are connected in parallel to form one large communicating vessel, and all odd-numbered hydraulic chambers are connected in parallel to form another large communicating vessel. Regardless of the rotation of the inner rod, the pressure in all chambers subjected to force in the same direction is absolutely equal.

[0041] The three-way channel includes a horizontal channel and a vertical channel. The horizontal channel is used to connect the inner ring groove and the outer ring groove, and the vertical channel is used to screw in the second regulating needle valve. The lower end of the second regulating needle valve has a taper. Similar to Embodiment 2, by changing the opening of the second regulating needle valve, the fluid flow resistance between all even-numbered sector hydraulic chambers and all odd-numbered sector hydraulic chambers can be adjusted simultaneously.

[0042] The working principle of this embodiment is as follows: When the cutting head is subjected to a pulse impact (e.g., clockwise twisting), the elastic inner rod rotates clockwise, and all even-numbered hydraulic chambers are simultaneously squeezed. Silicone oil is simultaneously forced upwards into the inner annular groove through the first through-hole of each chamber's top cover. Since the inner annular grooves are interconnected, the pressure in each even-numbered chamber quickly equalizes. The silicone oil can only squeeze through the gap of the second adjusting needle valve and flow into the outer annular groove, which is also interconnected. The silicone oil then flows down through the second through-hole to replenish the expanding odd-numbered hydraulic chambers.

[0043] The beneficial effects of this embodiment are as follows: Since all even-numbered cavities are connected through the inner ring groove and all odd-numbered cavities are connected through the outer ring groove, the pressure of each cavity in the same direction is always consistent. This means that the inner rod is completely self-balanced in terms of force and will not generate lateral force, thus avoiding the problem of eccentric wear.

[0044] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the present invention.

Claims

1. A backlash-free transmission structure for machine tools, comprising a gearbox body (1), characterized in that, It also includes a transmission wheel assembly (2) and a backlash elimination assembly (3) disposed within the gearbox body (1); The transmission wheel assembly (2) includes a drive wheel (21), a first large gear (22) and a second large gear (23) that mesh with both sides of the drive wheel (21), and a first small gear (24) and a second small gear (25) that mesh with the tooth surfaces on both sides of the rack. The first large gear (22) and the first small gear (24) are coaxially arranged, and the second large gear (23) is arranged on the same central shaft (27) as the second small gear (25) through a bearing (26). The backlash elimination assembly (3) includes a composite damping element (31) disposed on the upper end of the second large gear (23) and a tightening disc (32) disposed on the upper end of the composite damping element (31). The composite damping component (31) includes an elastic inner rod (311) disposed on the upper end of the central shaft (27), a rigid outer tube (312) sleeved on the elastic inner rod (311) and connected at its top end to the tightening disc (32), a flange (313) disposed on the lower end of the rigid outer tube (312) and bolted to the upper end of the second large gear (23), a limiting spline (314) disposed on the outer wall of the central shaft (27) and located above the second large gear (23), and a flange (313) disposed on the rigid outer tube (312). A limiting spline groove (315) is formed on the inner wall of the outer tube (312) and cooperates with the limiting spline (314). A closed annular cavity (316) is formed between the outer wall of the elastic inner rod (311) and the inner wall of the rigid outer tube (312). The annular cavity (316) is filled with a damping layer. A micro gap is reserved between the limiting spline groove (315) and the limiting spline (314). The top end of the elastic inner rod (311) is connected to the middle of the tightening disc (32) through a tight-fitting spline (317).

2. The backlash-free transmission structure for machine tools according to claim 1, characterized in that, The composite damping element (31) further includes a moving blade (318) disposed on the elastic inner rod (311) and extending toward the rigid outer tube (312), and a fixed blade (319) disposed on the inner wall of the rigid outer tube (312) and extending toward the elastic inner rod (311). The moving blade (318) and the fixed blade (319) divide the annular cavity (316) into multiple hydraulic chambers.

3. The backlash-free transmission structure for machine tools according to claim 2, characterized in that, The backlash elimination assembly (3) further includes a first damping adjustment member (33) disposed on the composite damping member (31) for adjusting the flow resistance; the first damping adjustment member (33) includes a radial flow channel (331) disposed on the fixed blade (319) for connecting two adjacent hydraulic chambers, a vertical oil passage (332) disposed in the thickness direction of the fixed blade (319) and extending from the top of the fixed blade (319) to the radial flow channel (331), and a first adjusting needle valve (333) passing through the tightening disc (32) and extending into the vertical oil passage (332), the lower end of the first adjusting needle valve (333) having a taper.

4. The backlash-free transmission structure for machine tools according to claim 2, characterized in that, The backlash elimination assembly (3) further includes a second damping adjustment member (34) disposed on the tightening disc (32) for adjusting flow resistance; the second damping adjustment member (34) includes an inner ring groove (341) and an outer ring groove (342) concentrically disposed inside the tightening disc (32), a plurality of first through holes (343) disposed on the lower surface of the tightening disc (32) and above the even-numbered hydraulic chambers and communicating with the inner ring groove (341), a plurality of second through holes (344) disposed on the lower surface of the tightening disc (32) and above the odd-numbered hydraulic chambers and communicating with the outer ring groove (342), a three-way channel (345) disposed between the inner ring groove (341) and the outer ring groove (342) and extending upward, and a second adjusting needle valve (346) disposed in the three-way channel (345), the lower end of the second adjusting needle valve (346) having a taper.

5. A backlash-free transmission structure for machine tools according to claim 3 or 4, characterized in that, The elastic inner rod (311) is a solid column made of spring steel, and its lower end is interference-fitted with the central shaft (27).

6. The backlash-free transmission structure for machine tools according to claim 5, characterized in that, The arc length of the micro-gap in the circumferential direction is equal to the maximum meshing gap accumulated by the gap-eliminating component (3).

7. The backlash-free transmission structure for machine tools according to claim 5, characterized in that, The composite damping component (31) also includes a sealing ring (320) disposed on the outer wall of the central shaft (27) and located below the limiting spline groove (315).

8. The backlash-free transmission structure for machine tools according to claim 1, characterized in that, The damping layer is dimethyl silicone oil or phenyl silicone oil.

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