A zero-backlash five-axis cam roller numerical control rotary table precision transmission structure

Abstract

The application discloses a zero-backlash five-axis cam roller numerical control rotary table precision transmission structure and belongs to the technical field of high-end numerical control machine tool core components, and solves the problems of difficult elimination of the gap between the existing cam rotary table, low bearing precision, brake temperature rise misalignment, multi-station synchronous difference and the like; the base is additionally provided with a horizontal sliding shaft cooperating with a cradle swing, and five-axis five-direction linkage is realized through workbench rotation; coaxial reverse double-arc cam is adopted to be matched with a pre-pressing gasket to realize self-adaptive zero-backlash rolling transmission; a hot die forging integrated forming process is adopted for a needle roller bearing to improve machining precision; time grating sensing and BP neural network are integrated to form mechanical+algorithm double error compensation, and a brake is provided with a circulating oil path cooling structure. The application has excellent positioning and repeat precision, can realize multi-workbench synchronous operation through single driving of multiple groups in series, effectively replaces imported products, is suitable for 3C, automobile and aviation multi-specification machining centers, and has high precision, heavy load and long-time precision maintenance.

Description

Technical Field

[0001] This invention relates to the field of core components technology for high-end CNC equipment, specifically to a zero-backlash five-axis cam roller CNC rotary table precision transmission structure, which is suitable for high-end CNC equipment such as vertical / horizontal machining centers and five-axis linkage machining centers, and can realize high-precision and high-efficiency machining of complex curved surface parts. Background Technology

[0002] As the core indexing component of a CNC machine tool, the CNC rotary table's transmission accuracy, rigidity, and holding capacity directly determine the overall machining accuracy and efficiency. Currently, most mainstream CNC rotary tables in the industry adopt a worm gear transmission structure. This structure has inherent defects in long-term use: First, the worm gear meshing surface is based on sliding friction, which wears quickly and generates transmission backlash after a period of operation, leading to a decrease in indexing accuracy and requiring periodic calibration and adjustment; second, sliding friction transmission has low efficiency and generates a large amount of heat, which can cause thermal deformation of components, further reducing machining accuracy; third, it has weak resistance to cutting loads, making it difficult to meet the needs of heavy cutting conditions.

[0003] To address the aforementioned issues with worm gear structures, the industry has gradually introduced cam roller CNC rotary tables, replacing sliding friction with rolling friction. This significantly improves transmission efficiency and accuracy retention. However, existing cam roller rotary tables still have several technical shortcomings: 1. Most of them adopt a single cam transmission structure, which has inherent transmission backlash when switching between forward and reverse directions, and cannot achieve true zero backlash transmission; some double cam backlash correction structures use parallel double shafts to drive forward and reverse directions respectively, which is complex in structure and large in size, and cannot adaptively compensate for the backlash caused by long-term wear.

[0004] 2. The matching needle roller bearings are mostly machined by turning blanks. The concentricity accuracy of the rollers and sleeves is low, usually only about 3μm. Combined with the cumulative assembly error of other parts, the indexing repeatability of the turntable can only reach the level of 10 arcseconds, which is difficult to meet the requirements of ultra-high precision machining.

[0005] 3. The brake locking mechanism is mostly a conventional friction plate structure. When the brake is continuously locked, the heat generated by friction cannot be dissipated in time, which will cause thermal deformation of the turntable components, resulting in drift in positioning accuracy and affecting the stability of processing.

[0006] 4. The error compensation system is independent of the transmission structure. It can only compensate for the lag of the output angle and cannot eliminate the gap error from the source of the transmission. The compensation effect is limited.

[0007] 5. Traditional five-axis rotary tables only include two motion axes: the cradle swing axis and the table rotation axis. The lateral displacement of the workpiece needs to be achieved by the machine tool's own axis system. For long, multi-station continuous processing scenarios, multiple clamping and alignment are required, resulting in low processing efficiency and large cumulative errors.

[0008] In addition, existing multi-station synchronous turntables mostly adopt a scheme of driving multiple motors separately, which is difficult and costly to control synchronously. Furthermore, the inconsistency of errors in multiple transmission chains leads to poor synchronization accuracy between workstations. On the other hand, the single-drive series scheme lacks mature and compact structural design in the industry, which cannot guarantee the synchronization accuracy and load-bearing rigidity of multiple workstations.

[0009] Therefore, there is an urgent need to develop a brand-new zero-backlash five-axis cam roller CNC rotary table precision transmission structure, and to make technological breakthroughs from multiple dimensions such as transmission structure, bearing precision, heat dissipation design, error compensation, and multi-axis layout, so as to solve many pain points of existing technologies. Summary of the Invention

[0010] The purpose of this invention is to overcome the shortcomings of the prior art and provide a precision transmission structure for a zero-backlash five-axis cam roller CNC rotary table. This structure solves the technical problems of rapid accuracy decay of traditional worm gear rotary tables, the inability of existing cam rotary tables to maintain zero-backlash transmission, low bearing accuracy, accuracy drift caused by brake temperature rise, low clamping efficiency in five-axis machining, and poor synchronization accuracy in multi-station operation. It achieves a five-axis indexing transmission with high rigidity, high precision, long life, and high efficiency.

[0011] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: A precision transmission structure for a zero-backlash five-axis cam roller CNC rotary table includes a rotary table base, a cradle rotating frame, a rotary table, a drive module, a cam roller transmission mechanism, a needle roller bearing assembly, a brake locking mechanism, and an error compensation detection module.

[0012] The upper surface of the turntable base is provided with a horizontal sliding guide structure to form a third motion axis. The cradle rotating frame is slidably installed on the horizontal sliding guide structure and hinged to the turntable base to form a first swing axis (A axis). The turntable rotating worktable is rotatably installed inside the cradle rotating frame to form a second rotation axis (C axis). Together with the tilting swing and circumferential rotation of the turntable rotating worktable, a five-axis five-directional motion layout is formed.

[0013] The cam roller transmission mechanism includes a first arc-shaped cam, a second arc-shaped cam, and an annular roller assembly arranged coaxially and in opposite directions. The first arc-shaped cam and the second arc-shaped cam have opposite helical directions and mesh synchronously with the same annular roller assembly. A pre-compressed elastic shim is provided between the two cams, which can adaptively adjust the meshing clearance to achieve continuous zero-backlash rolling transmission.

[0014] The needle roller bearing assembly adopts a one-piece forged blank structure and serves as a supporting rotary component for cam transmission.

[0015] The error compensation detection module is integrated with the cam roller transmission mechanism, and combined with the zero backlash design of the mechanical structure and dynamic compensation algorithm, a dual precision guarantee system is formed.

[0016] The brake locking mechanism has a built-in oil circulation cooling system that can remove frictional heat in real time and suppress accuracy drift caused by temperature rise.

[0017] In a preferred embodiment, the first and second arc-shaped cams are fixedly mounted on the same input shaft. The preloaded elastic washer is a disc spring assembly, sleeved on the input shaft and located between the opposite end faces of the two cams. During assembly, the two cams are axially preloaded by locking the nut, causing the elastic washer to generate a preload force, forcing the helical ridges of the two cams to tightly adhere to the two working surfaces of the rollers, eliminating transmission backlash during forward and reverse rotation. When the cams or rollers wear down, the elastic restoring force of the preloaded elastic washer automatically pushes the two cams to axially misalign, compensating for the wear and maintaining a zero-backlash transmission state, thereby increasing transmission rigidity by more than 20%.

[0018] In a preferred embodiment, the horizontal sliding guide structure adopts a composite layout of linear guide rails and hydrostatic guide rails. The contact surface of the guide rails is coated with a nano-ceramic wear-resistant coating. The sliding stroke is ≥200mm, the positioning accuracy is ≤0.01mm, and the maximum horizontal load of the worktable can reach 120kg. The sliding seat is installed on the guide rail through a bottom slider and is driven by a servo motor in conjunction with a lead screw module to achieve horizontal reciprocating motion.

[0019] In a preferred embodiment, the needle roller bearing assembly includes rollers, bushings, needle rollers, and retaining rings; the rollers and bushings are integrally formed by hot forging, resulting in a denser raw material structure, more continuous metal flow lines, and significantly improved reliability and service life; after precision machining with specialized grinding equipment and positioning fixtures, the concentricity of the rollers and bushings is ≤0.5μm, and the overall bearing assembly accuracy is ≤1μm, which can control the rotary table indexing repeatability within 2 arcseconds.

[0020] In a preferred embodiment, the error compensation detection module includes an absolute time-grid displacement sensor installed inside the annular roller assembly, a real-time parameter acquisition unit, and a BP neural network prediction compensation unit. The absolute time-grid displacement sensor directly acquires the actual rotation angle of the roller assembly, which is then transmitted to the CNC system via the real-time parameter acquisition unit. The BP neural network prediction compensation algorithm achieves dynamic accuracy compensation of ±0.01mm, with a data transmission delay of ≤0.02s. Combined with the zero-backlash design of the mechanical structure, the rotary table indexing accuracy is guaranteed from both the source and the end.

[0021] In a preferred embodiment, the brake locking mechanism is a multi-plate hydraulic brake structure, comprising alternating dynamic friction plates and static friction plates; the dynamic friction plates rotate synchronously with the driven turntable, and the static friction plates are fixed to the housing of the cradle rotating frame; the oil circuit circulation cooling system is arranged around the friction plate assembly, and the cooling oil channels are integrated inside the cradle housing, achieving locking oil supply and cooling circulation through an external hydraulic station; this structure can achieve a braking torque of up to 4800 N·m, and the axial and radial runout of the worktable is controlled within 0.008 mm, with a temperature rise of ≤5℃ after 1000 consecutive braking cycles, completely solving the problem of accuracy attenuation caused by brake temperature rise.

[0022] In a preferred embodiment, the cradle rotating frame adopts an integrated cast steel hollow reinforced structure with a series dual spindle mounting position inside, which can be adapted to the assembly of the oscillating grinding spindle assembly to realize continuous online grinding of the cam profile surface. After processing, the surface finish Ra<0.6μm can reduce the transmission noise by 22%.

[0023] In one preferred embodiment, the rotary table has six sets of T-shaped clamping grooves evenly arranged in the circumferential direction, which is compatible with both vertical and horizontal installation methods and can be adapted to different types of CNC machine tools; the internal oil circuit of the table adopts an integrated surrounding layout, which can achieve full circulation lubrication for all moving parts, reduce wear of parts, and extend the service life of the equipment by more than 40%.

[0024] In one preferred embodiment, the contours of the first and second arc-shaped cams are optimized using an adaptive non-uniform rational B-spline curve design, and micro-structure textures are set on the cam surface. Combined with a real-time monitoring and detection system, the realism of the cam surface machining can be improved by more than 12%, thus optimizing the transmission smoothness.

[0025] In a preferred embodiment, the input shaft can be replaced with an extended through shaft structure, extending axially to connect 2-4 sets of cam-roller transmission mechanisms arranged in series, synchronously driven by a single drive module; each transmission mechanism includes an independent coaxial reverse double-arc cam, a preloaded elastic washer, and an annular roller group, all arc cams are fixed to the input shaft by flat keys, and the installation phases are completely consistent; each annular roller group is connected to an independent rotary table, and all tables are arranged side by side along the input shaft axis; this structure can achieve a multi-table operation synchronization error of ≤1 arcsecond, maintain a workpiece processing qualification rate of more than 99.8%, and increase the output of parts by 180% in the same processing time.

[0026] Due to the application of the above technical solution, the beneficial effects of this application compared with the prior art are as follows: 1. Continuous zero backlash transmission with excellent rigidity and precision retention: The structure design adopts a coaxial reverse double arc surface cam with pre-compressed elastic shims. Pre-tightening during assembly eliminates initial side backlash, and wear can be adaptively compensated during operation, maintaining zero backlash transmission throughout the entire process. Compared with the traditional single cam structure transmission, the rigidity is increased by 20%, the precision retention life is extended by 35%, and no periodic calibration and adjustment are required.

[0027] 2. Five-axis, five-direction layout, improving both processing efficiency and accuracy: An independent horizontal sliding axis is added to the traditional two-axis and five-axis rotary table, which can complete the continuous processing of five sides of the workpiece in one clamping, reducing the number of clamping times and alignment errors, improving processing efficiency by 40% and overall processing accuracy by 30%.

[0028] 3. Ultra-high precision bearings with industry-leading indexing accuracy: The needle roller bearing adopts a hot die forging integrated molding process combined with precision grinding, which improves the concentricity accuracy by 6 times compared with traditional machined bearings. The rotary table indexing repeatability can be controlled within 2 arcseconds, while the bearing reliability and service life are improved by 50%.

[0029] 4. Dual precision guarantee and stable dynamic accuracy: The zero-backlash mechanical structure design is combined with the dynamic error compensation algorithm to eliminate backlash error from the transmission source and dynamically correct running error from the output end. The positioning accuracy can reach within 5 arcseconds, and the dynamic error is reduced by more than 80%.

[0030] 5. Cooling brake design completely solves the problem of temperature rise: The brake mechanism has a built-in circulating cooling oil circuit, which can remove friction heat in real time. The continuous braking temperature rise is controlled within 5℃, which completely solves the precision drift problem caused by thermal deformation of traditional brake structure. At the same time, the braking torque is large, the bounce is small, and the locking stability is excellent.

[0031] 6. Single-drive multi-station series connection, high synchronization accuracy and low cost: It can be expanded into a single-motor drive multi-station series structure, sharing the same input shaft and transmission chain. Compared with the multi-motor drive solution, it has higher synchronization accuracy, more compact structure and lower cost, significantly improving production capacity and adapting to batch automated processing scenarios. Attached Figure Description

[0032] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0033] Figure 1 This is a schematic diagram of the overall structure of the present invention; Figure 2 This is a cross-sectional view of the cam roller transmission mechanism of the present invention; Figure 3 This is a schematic diagram of the structure of the needle roller bearing assembly of the present invention; Figure 4 This is a cross-sectional view of the brake locking mechanism of the present invention; The components include: 1. Turntable base; 11. Horizontal sliding guide structure; 2. Cradle rotating frame; 3. Turntable rotating worktable; 4. Drive module; 5. Cam roller transmission mechanism; 51. First arc surface cam; 52. Second arc surface cam; 53. Annular roller assembly; 54. Preloaded elastic pad; 55. Input shaft; 6. Needle roller bearing assembly; 61. Roller; 62. Roller sleeve; 63. Needle roller; 64. Retaining ring; 7. Brake locking mechanism; 71. Dynamic friction plate; 72. Static friction plate; 8. Error compensation detection module. Detailed Implementation

[0034] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort should fall within the scope of protection of the present application.

[0035] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate for the embodiments of this application described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0036] In this application, the terms "upper," "lower," "left," "right," "front," "rear," "top," "bottom," "inner," "outer," "middle," "vertical," "horizontal," "lateral," and "longitudinal" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are primarily for the purpose of better describing the invention and its embodiments, and are not intended to limit the indicated device, element, or component to having a specific orientation, or to be constructed and operated in a specific orientation.

[0037] Furthermore, in addition to indicating direction or positional relationship, some of the aforementioned terms may also have other meanings. For example, the term "above" may also be used in certain situations to indicate a dependency or connection. Those skilled in the art can understand the specific meaning of these terms in this invention based on the specific circumstances.

[0038] Furthermore, the terms "installation," "setup," "equipped with," "connection," "linking," and "socketing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral structure; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium, or an internal connection between two devices, components, or parts. Those skilled in the art can understand the specific meaning of these terms in this invention based on the specific circumstances.

[0039] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0040] Example 1 like Figure 1-4 As shown, the present invention discloses a zero-backlash five-axis cam roller CNC rotary table precision transmission structure, which includes eight main components: a rotary table base 1, a cradle rotating frame 2, a rotary table 3, a drive module 4, a cam roller transmission mechanism 5, a needle roller bearing assembly 6, a brake locking mechanism 7, and an error compensation detection module 8. The specific structure and connection relationship of each part are as follows: 1. Overall layout and support structure of five-axis motion.

[0041] like Figure 1 As shown, the turntable base 1 is a long, horizontal cast steel base, serving as the mounting and bearing foundation for the entire turntable. A horizontal sliding guide structure 11 is installed on its upper surface, forming the third motion axis X'. The horizontal sliding guide structure 11 includes two parallel linear guides, a hydrostatic slide rail pair, and a sliding drive screw module. The guide rail contact surfaces are coated with a nano-ceramic wear-resistant coating to reduce wear and improve motion stability. The sliding seat is mounted on the linear guides via a bottom slider. The sliding drive servo motor drives the sliding seat to move horizontally and linearly along the guides via the screw module. In this embodiment, the sliding stroke is 220mm, and the positioning accuracy can reach 0.008mm.

[0042] The upper surface of the sliding seat is symmetrically and vertically fixed with two support arms, forming an upward-opening installation space between the two support arms; the cradle rotating frame 2 is an integral U-shaped cast steel hollow reinforced structure, including a left side wall, a right side wall and a bottom connecting beam, and the cavity between the left side wall and the right side wall is the U-shaped installation space; A-axis rotating shafts are fixed at the center of the outer walls on both sides of the cradle rotating frame 2, and the two A-axis rotating shafts are respectively hinged to the upper part of the left and right support arms through bearings to form the first swing axis (A-axis). In this embodiment, the swing range is -120° to +120°.

[0043] The A-axis swing drive assembly, including a servo motor and a precision reducer, is fixedly installed on the outer wall of the right support arm. The output end of the reducer is coaxially connected to the right A-axis rotating shaft, directly driving the cradle rotating frame 2 to swing back and forth around the A-axis.

[0044] The rotary table 3 is a circular platform, suspended in the center of the U-shaped mounting space of the cradle rotating frame 2. The back of the rotary table 3 is coaxially fixed to the driven turntable of the cam roller transmission mechanism 5 by bolts evenly distributed around the circumference. The driven turntable is supported on the inner wall of the left side of the cradle rotating frame by cross roller bearings, which can simultaneously withstand radial force, axial force and overturning moment, ensuring rotational accuracy and load-bearing rigidity, forming a second rotating axis (C-axis) with a rotation range of 0° to 360°.

[0045] The drive module 4 is a C-axis servo drive assembly, including a servo motor and a precision reducer, which is fixedly installed on the outer wall of the right side of the cradle rotating frame 2 via a flange. The output shaft of the drive module 4 extends horizontally into the interior of the cradle side wall and is coaxially fixed to the right end of the input shaft 55 of the cam roller transmission mechanism via a coupling, providing power input for the C-axis rotation.

[0046] By coordinating the three motion axes of X'-axis horizontal sliding, A-axis cradle swing, and C-axis table rotation, combined with the workpiece's own multi-degree-of-freedom machining posture, a five-axis, five-directional motion layout is formed. The continuous machining of five sides of the workpiece can be completed in one clamping, greatly reducing the number of clamping times and alignment errors.

[0047] 2. Cam roller transmission mechanism and zero backlash realization principle.

[0048] like Figure 2 As shown, the cam roller transmission mechanism 5 is integrated and installed inside the left side wall of the cradle rotating frame 2. It is the core transmission component for C-axis rotation and includes a first arc-shaped cam 51, a second arc-shaped cam 52, an annular roller group 53, a pre-compressed elastic pad 54, and an input shaft 55 arranged coaxially and in opposite directions.

[0049] The input shaft 55 is arranged horizontally, and its axis intersects the A-axis perpendicularly. The left and right ends of the input shaft 55 are supported in the mounting holes on the side wall of the cradle by deep groove ball bearings, and can rotate freely. The first arc-shaped cam 51 and the second arc-shaped cam 52 are both cylindrical cams with helical ridges on their outer circumference. The helical ridges of the two cams rotate in opposite directions and have the same helix angle. They are sequentially fitted onto the middle section of the input shaft 55 and are circumferentially fixed and rotate synchronously with the input shaft by a flat key.

[0050] The preload elastic pad 54 is a set of disc springs, which are sleeved on the input shaft 55 and clamped between the opposite end faces of the first arc surface cam 51 and the second arc surface cam 52. A locking nut is provided at the left end of the input shaft 55. When assembling, tightening the locking nut will axially compress the two cams, causing the middle preload elastic pad 54 to generate a compression preload force, which forces the spiral ridges of the two cams to tightly adhere to the two working surfaces of the roller, completely eliminating the transmission backlash when switching between forward and reverse rotation, and achieving initial zero backlash.

[0051] When the turntable operates for a long time, the cam ridges or rollers will wear out. The elastic restoring force of the preloaded elastic pad 54 will automatically push the two cams to produce axial misalignment, compensate for the gap caused by wear, and continuously maintain a zero backlash transmission state without the need for manual periodic calibration and adjustment. Compared with the traditional single cam transmission, this structure improves the transmission rigidity by more than 20% and extends the accuracy maintenance life by 35%.

[0052] The annular roller assembly 53 includes a driven turntable and multiple cylindrical rollers; the multiple cylindrical rollers are uniformly and vertically installed along the circumferential direction of the right end face of the driven turntable, and the axis of the rollers is parallel to the axis of the driven turntable; the helical ridges of two arc-shaped cams are simultaneously embedded in the gap between adjacent rollers to form rolling engagement with the rollers.

[0053] During operation, the drive module 4 drives the input shaft 55 to rotate, and the input shaft drives two arc-shaped cams to rotate synchronously. The spiral ridges of the cams push the rollers to move in the circumferential direction, which in turn drives the driven turntable and the rotary table 3 fixed to it to complete the C-axis rotation. Due to the use of rolling friction transmission, the transmission efficiency is high, the heat generation is low, and the wear is low.

[0054] 3. Structure of needle roller bearing assembly.

[0055] like Figure 3 As shown, the needle roller bearing assembly 6 includes rollers 61, sleeves 62, needle rollers 63 and retaining rings 64. As a supporting rotary component of the cam transmission mechanism, it is installed at the mating position of the input shaft and the cam to ensure rotational accuracy and support rigidity.

[0056] Both the roller 61 and the bushing 62 are integrally formed by hot forging. After forging, the raw material has a denser structure and more continuous and complete metal flow lines. Compared with traditional machined blanks, the reliability and service life of the bearing are significantly improved by more than 50%, while the utilization rate of raw materials is also higher.

[0057] After the forged blank is precision machined multiple times by special grinding equipment and positioning fixture, the concentricity of the roller and bushing is ≤0.5μm, and the overall assembly accuracy of the bearing is ≤1μm. The indexing repeatability of the turntable can be controlled within 2 arcseconds, which is far higher than the industry standard.

[0058] 4. Error compensation detection module.

[0059] The error compensation detection module 8 includes an absolute time-grating displacement sensor, a real-time parameter acquisition unit, and a BP neural network prediction compensation unit.

[0060] The absolute time-grid displacement sensor is installed inside the annular roller assembly 53 and arranged coaxially with the driven turntable. It can directly collect the actual rotation angle of the roller assembly, avoiding the influence of errors in the intermediate links of the transmission chain. The collected angle data is transmitted to the machine tool CNC system through the real-time parameter acquisition unit. Through the algorithm calculation of the BP neural network prediction compensation unit, the dynamic error of the turntable is predicted and compensated in real time. The compensation accuracy can reach ±0.01mm, and the data transmission delay is ≤0.02s.

[0061] This module is deeply integrated with the zero-backlash design of the mechanical structure, eliminating static backlash error from the transmission source and correcting dynamic operating error from the output end, forming a dual precision guarantee system of "structure + algorithm", which can improve the positioning accuracy of the turntable to within 5 arcseconds and reduce dynamic error by more than 80%.

[0062] 5. Brake locking mechanism.

[0063] like Figure 4 As shown, the brake locking mechanism 7 is a multi-plate hydraulic brake structure, which is sleeved on the outer periphery of the driven turntable and installed in the mounting cavity on the left side wall of the cradle rotating frame. It includes alternating dynamic friction plates 71, static friction plates 72, hydraulic pistons, and cooling oil passages.

[0064] The moving friction plate 71 is connected to the driven turntable via a spline and can rotate synchronously with the driven turntable; the stationary friction plate 72 is fixed to the inner wall of the cradle housing via a spline and cannot rotate; the hydraulic piston is located on one side of the friction plate assembly and is driven by an external hydraulic station.

[0065] When locking is required, hydraulic oil pushes the piston to press the friction plate assembly, and the turntable is locked by the friction between the moving and stationary friction plates. In this embodiment, the braking torque can reach 4800 N·m. After locking, the axial and radial runout of the worktable are controlled within 0.008 mm, which can withstand large cutting forces without displacement. The cooling oil channels are arranged around the friction plate assembly and integrated inside the cradle housing, which is part of the oil circuit cooling system. During the locking process, the cooling oil continuously circulates in the oil channels, which can promptly remove the heat generated by friction. According to actual tests, the temperature rise after 1000 consecutive braking cycles is ≤5℃, which completely solves the industry pain point of thermal deformation and precision drift caused by friction heat in traditional braking mechanisms.

[0066] 6. Cradle and workbench auxiliary structure.

[0067] The cradle rotating frame 2 adopts an integrated cast steel hollow reinforced structure, which reduces weight and swing drive load while ensuring overall rigidity. The cradle is equipped with a series dual spindle mounting position, which can be adapted to the assembly of the oscillating grinding spindle assembly, so as to realize online continuous grinding of the cam profile surface. The cam can be precision repaired without disassembly. The surface finish after processing is Ra<0.6μm, which can effectively reduce the transmission noise by 22%.

[0068] The upper surface of the rotary table 3 is uniformly provided with 6 sets of T-shaped clamping grooves in the circumferential direction, which can quickly clamp the workpiece and the fixture through T-bolts. This structure is compatible with both vertical and horizontal installation methods. It can be installed vertically on a vertical machining center or docked horizontally with a horizontal machining center. It is suitable for different types of CNC machine tools and has strong versatility.

[0069] The oil circuit inside the worktable and cradle housing adopts an integrated surrounding layout, which can achieve full circulation lubrication for all moving parts such as bearings, cam roller pairs, and brake mechanisms, reducing parts wear and extending the service life of the equipment by more than 40%.

[0070] In addition, the contours of the first arc-shaped cam 51 and the second arc-shaped cam 52 are optimized by an adaptive non-uniform rational B-spline curve design, which makes the meshing process between the cam and the roller smoother and reduces impact vibration; the cam surface is provided with micro-structure texture, which can store lubricating oil film and reduce friction and wear; with the real-time monitoring and detection system, the cam surface status can be monitored online, which improves the realism of the cam surface processing by more than 12%.

[0071] 7. Multi-stage serial expansion structure.

[0072] This invention can be extended to a multi-worktable synchronous drive structure, replacing the standard input shaft with an extended through shaft structure, which extends axially to connect 2-4 sets of cam roller transmission mechanisms arranged in series, and is synchronously driven by a single drive module 4; this embodiment is illustrated using 2 sets in series as an example.

[0073] The two sets of cam roller transmission mechanisms are the first and second transmission mechanisms, respectively, and are arranged side by side along the horizontal axis. The housings of the two mechanisms are integrally cast to form an integral cast housing, ensuring overall rigidity and installation coaxiality. Each transmission mechanism contains an independent coaxial reverse double arc surface cam, a preloaded elastic washer, and an annular roller assembly. All arc surface cams are fixed to the extended input shaft by a flat key, and the installation phase is completely consistent to ensure synchronous rotation.

[0074] Each set of annular rollers is fixedly connected to an independent rotary table, namely the first worktable and the second worktable. The two worktables are arranged side by side along the input shaft axis with the table surfaces facing the same direction, allowing two workpieces to be clamped at the same time for synchronous processing.

[0075] During operation, the drive module 4 drives the extended input shaft to rotate, and the two sets of cams rotate synchronously and in phase, driving the corresponding worktables to rotate synchronously. Since they share the same input shaft and the transmission chain length and structure are completely consistent, there is no synchronization error due to multi-motor control. The synchronization error of multi-worktable operation is ≤1 arcsecond, and the workpiece processing qualification rate is stably maintained at over 99.8%. The output of parts is increased by 180% in the same processing time, making it very suitable for automated continuous processing of batch parts.

[0076] 8. Overall working principle.

[0077] The working process and principle of this invention are as follows: When the C-axis rotates, the drive module 4 drives the input shaft 55 to rotate, and the input shaft drives the first arc-shaped cam 51 and the second arc-shaped cam 52, which are arranged in opposite directions on the same axis, to rotate synchronously. The spiral ridges of the two cams simultaneously mesh with the same annular roller group 53. Through the adaptive pre-tightening of the pre-compression elastic pad 54, the meshing surfaces are always kept in zero-gap contact, which drives the annular roller group and the rotary table 3 to rotate smoothly, realizing zero-backlash indexing transmission.

[0078] When the A-axis swings, the A-axis swing drive assembly drives the cradle rotating frame 2 to swing back and forth around the A-axis, adjusting the tilting machining angle of the workpiece; when the X' axis slides, the sliding drive module drives the entire cradle and worktable assembly to move along the horizontal guide rail, adjusting the lateral machining position of the workpiece; the three motion axes work together to realize the machining of complex curved surfaces in five axes and five directions.

[0079] During operation, the absolute time-grid displacement sensor collects the actual rotation angle data of the roller assembly in real time and transmits it to the BP neural network prediction and compensation unit to dynamically correct the turntable position error and ensure machining accuracy. When locking is required, the hydraulic system pushes the piston to press the friction plate assembly to achieve locking, while the cooling oil circuit circulates to dissipate heat and suppress temperature rise and deformation.

[0080] When expanding the multi-station serial structure, a single drive module drives multiple cam transmission mechanisms to operate synchronously through an extended through shaft, enabling high-precision synchronous processing of multiple worktables and improving batch processing efficiency.

[0081] Example 2 This embodiment is a small, precision, zero-backlash five-axis cam roller CNC rotary table, suitable for precision parts processing in industries such as 3C electronics and medical devices.

[0082] Main technical parameters:

[0083] Worktable diameter: φ170mm.

[0084] Maximum horizontal load: 50kg.

[0085] A-axis swing range: -110° to +110°.

[0086] C-axis rotation range: 0° to 360°.

[0087] Repeatability accuracy: A-axis ≤ 4″, C-axis ≤ 3″.

[0088] Positioning accuracy: A-axis ≤ 12″, C-axis ≤ 10″.

[0089] Braking torque: 1200 N·m.

[0090] Maximum speed: 120 rpm for C-axis.

[0091] Horizontal sliding stroke: 150mm.

[0092] Structural features: Adopting a lightweight design, the cradle rotating frame 2 is made of cast aluminum alloy, with an overall weight of only 85kg; The needle roller bearing assembly 6 adopts a miniaturized design, with the roller 61 having a diameter of 6mm and the sleeve 62 having a thickness of 3mm; Drive module 4 uses a combination of servo motor and planetary reducer with a transmission ratio of 1:30; The brake locking mechanism 7 adopts a small multi-plate hydraulic brake with a built-in micro oil circuit cooling system.

[0093] Applicable scenarios: Suitable for vertical machining centers, used for machining mobile phone frames, laptop casings, precision parts for medical devices, etc.

[0094] Example 3 This embodiment is a general-purpose standard zero-backlash five-axis cam roller CNC rotary table, which is the most widely used specification on the market and is suitable for processing general parts in industries such as mold making and automotive parts.

[0095] Main technical parameters: Worktable diameter: φ250mm.

[0096] Maximum horizontal load: 100kg.

[0097] A-axis swing range: -120° to +120°.

[0098] C-axis rotation range: 0° to 360°.

[0099] Repeatability accuracy: A-axis ≤ 4″, C-axis ≤ 3″.

[0100] Positioning accuracy: A-axis ≤ 15″, C-axis ≤ 12″.

[0101] Braking torque: 2800 N·m.

[0102] Maximum speed: 80 rpm for C-axis.

[0103] Horizontal sliding stroke: 200mm.

[0104] Structural features: The cradle rotating frame 2 adopts a cast steel hollow reinforced structure, which has good rigidity and strong vibration resistance; The needle roller bearing assembly 6 adopts a standard design, with roller 61 having a diameter of 10mm and sleeve 62 having a thickness of 5mm; Drive module 4 uses a combination of servo motor and harmonic reducer with a transmission ratio of 1:50; The brake locking mechanism 7 adopts a medium-sized multi-plate hydraulic brake with a built-in standard oil circuit cooling system; It can be expanded into a dual-worktable series drive structure, driven synchronously by a single motor.

[0105] Applicable scenarios: Suitable for vertical / horizontal machining centers, for machining mold cavities, automotive engine parts, engineering machinery parts, etc.

[0106] Example 4 This embodiment is a heavy-duty, zero-backlash, five-axis cam roller CNC rotary table, suitable for machining heavy-duty parts in industries such as aerospace and shipbuilding.

[0107] Main technical parameters: Worktable diameter: φ320mm.

[0108] Maximum horizontal load: 200kg.

[0109] A-axis swing range: -100° to +100°.

[0110] C-axis rotation range: 0° to 360°.

[0111] Repeat positioning accuracy: A-axis ≤ 5″, C-axis ≤ 4″.

[0112] Positioning accuracy: A-axis ≤ 18″, C-axis ≤ 15″.

[0113] Braking torque: 4800 N·m.

[0114] Maximum speed: 50 rpm for C-axis.

[0115] Horizontal sliding stroke: 250mm.

[0116] Structural features: The cradle rotating frame 2 is made of thick-walled cast steel, which is extremely rigid and can withstand large cutting forces. The needle roller bearing assembly 6 adopts a heavy-duty design, with roller 61 having a diameter of 14mm and sleeve 62 having a thickness of 8mm; Drive module 4 uses a combination of servo motor and RV reducer with a transmission ratio of 1:80; The brake locking mechanism 7 adopts a large multi-plate hydraulic brake with a built-in enhanced oil circuit cooling system; The horizontal sliding guide structure 11 adopts a composite layout of widened linear guide rails and hydrostatic guide rails, which has a strong load-bearing capacity.

[0117] Applicable scenarios: Suitable for large vertical machining centers, used for machining aerospace structural parts, marine engine components, large molds, etc.

[0118] Example 5 This embodiment is a horizontal, dedicated, zero-backlash, five-axis cam roller CNC rotary table, specifically designed for horizontal machining centers and suitable for multi-face machining of box-type parts.

[0119] Main technical parameters: Workbench dimensions: 400mm × 400mm.

[0120] Maximum horizontal load: 300 kg.

[0121] A-axis swing range: -90° to +90°.

[0122] C-axis rotation range: 0° to 360°.

[0123] Repeat positioning accuracy: A-axis ≤ 5″, C-axis ≤ 4″.

[0124] Positioning accuracy: A-axis ≤ 20″, C-axis ≤ 16″.

[0125] Braking torque: 6500 N·m.

[0126] Maximum speed: 40 rpm for C-axis.

[0127] Horizontal sliding stroke: 300mm.

[0128] Structural features: It adopts a horizontal installation structure, with the turntable base 1 directly connected to the horizontal machining center worktable; Cradle rotating frame 2 adopts a box-type cast steel structure, which has strong torsional rigidity; The needle roller bearing assembly 6 adopts an ultra-heavy-duty design, with rollers 61 having a diameter of 18mm and sleeves 62 having a thickness of 10mm; Drive module 4 uses dual servo motors for synchronous drive, which has high output torque and stable operation; The brake locking mechanism 7 adopts an ultra-large multi-plate hydraulic brake with a built-in dual oil circuit cooling system; It can be expanded into a four-table series drive structure to realize multi-station continuous processing.

[0129] Applicable scenarios: Suitable for horizontal machining centers, used for machining box-type parts such as automotive gearbox housings, engine blocks, and hydraulic valve bodies.

[0130] Finally, it should be noted that the above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A precision transmission structure for a zero-backlash five-axis cam roller CNC rotary table, comprising a rotary table base, a cradle rotating frame, a rotary table, a drive module, a cam roller transmission mechanism, a needle roller bearing assembly, a brake locking mechanism, and an error compensation detection module, characterized in that: The upper surface of the turntable base is provided with a horizontal sliding guide structure to form a third motion axis. The cradle rotating frame is slidably installed on the horizontal sliding guide structure and hinged to the turntable base to form a first swing axis. The turntable rotating worktable is rotatably installed inside the cradle rotating frame to form a second rotation axis. Together with the tilting swing and circumferential rotation of the turntable rotating worktable, a five-axis, five-directional motion layout is formed. The cam roller transmission mechanism includes a first arc-shaped cam, a second arc-shaped cam, and an annular roller assembly arranged coaxially and in opposite directions. The first arc-shaped cam and the second arc-shaped cam have opposite helical directions and mesh synchronously with the same annular roller assembly. A pre-compressed elastic shim is provided between the two cams, and the meshing clearance is adaptively adjusted to achieve zero backlash rolling transmission. The needle roller bearing assembly adopts a one-piece structure formed from a forged blank. The error compensation detection module is integrated with the cam roller transmission mechanism to form a dual precision guarantee system of zero backlash in structure and dynamic algorithm compensation. The brake locking mechanism has a built-in oil circulation cooling system.

2. The precision transmission structure of the zero-backlash five-axis cam roller CNC rotary table according to claim 1, characterized in that: The first arc-shaped cam and the second arc-shaped cam are fixedly installed on the same input shaft. The preloaded elastic shim is a disc spring assembly, which is sleeved on the input shaft and clamped between the opposite end faces of the two cams. During assembly, the axial preload of the locking nut generates a preload force on the shim, which forces the two cam ridges to press tightly against the working surfaces on both sides of the roller to eliminate side clearance. After wear, the elastic restoring force of the shim automatically pushes the cam to axially misalign to compensate for the wear.

3. The precision transmission structure of the zero-backlash five-axis cam roller CNC rotary table according to claim 1, characterized in that: The horizontal sliding guide structure adopts a composite layout of linear guide rails and hydrostatic guide rails. The contact surface of the guide rails is coated with a nano-ceramic wear-resistant coating. The sliding seat is driven by a servo motor and a lead screw module to perform horizontal reciprocating motion. The sliding stroke is ≥200mm, the positioning accuracy is ≤0.01mm, and the maximum horizontal load of the worktable is 120kg.

4. The precision transmission structure of the zero-backlash five-axis cam roller CNC rotary table according to claim 1, characterized in that: The needle roller bearing assembly includes rollers, bushings, needles, and retaining rings. The rollers and bushings are integrally formed by hot forging and precision machined by special grinding equipment and positioning fixtures. The overall assembly accuracy of the bearing is ≤1μm, and the concentricity of the rollers and bushings during grinding is ≤0.5μm. The indexing repeatability accuracy of the turntable is controlled within 2 arcseconds.

5. The precision transmission structure of the zero-backlash five-axis cam roller CNC rotary table according to claim 1, characterized in that: The error compensation detection module includes an absolute time-grid displacement sensor installed inside the annular roller assembly, a real-time parameter acquisition unit, and a BP neural network prediction compensation unit. The absolute time-grid displacement sensor directly acquires the actual rotation angle of the roller assembly, and the prediction compensation algorithm achieves dynamic accuracy compensation of ±0.01mm, with a data transmission delay of ≤0.02s.

6. The precision transmission structure of the zero-backlash five-axis cam roller CNC rotary table according to claim 1, characterized in that: The brake locking mechanism is a multi-plate hydraulic brake structure, including alternating dynamic friction plates and static friction plates. The cooling oil channels of the oil circuit cooling system are integrated and arranged around the friction plate assembly inside the housing. The braking torque reaches 4800 N·m, and the axial and radial runout of the worktable is controlled within 0.008 mm. The temperature rise is ≤5℃ after 1000 consecutive braking cycles.

7. The precision transmission structure of the zero-backlash five-axis cam roller CNC rotary table according to claim 1, characterized in that: The cradle rotating frame adopts an integrated cast steel hollow reinforced structure, with a series dual spindle mounting position inside, which is adapted to the assembly of the oscillating grinding spindle assembly to realize continuous grinding of the cam profile surface, with a surface finish Ra<0.6μm.

8. The precision transmission structure of the zero-backlash five-axis cam roller CNC rotary table according to claim 1, characterized in that: The rotary table has 6 sets of T-shaped clamping grooves evenly arranged around its circumference, which are compatible with both vertical and horizontal installation methods. The internal oil circuit adopts an integrated surrounding layout to achieve full circulation lubrication of all moving parts.

9. The precision transmission structure of the zero-backlash five-axis cam roller CNC rotary table according to claim 1, characterized in that: The contours of the first and second arc-shaped cams are optimized using an adaptive non-uniform rational B-spline curve design, and microstructure textures are set on the cam surfaces, in conjunction with a real-time monitoring and detection system.

10. The precision transmission structure of the zero-backlash five-axis cam roller CNC rotary table according to claim 2, characterized in that: The input shaft can be replaced with an extended through shaft structure, which extends axially to connect 2-4 sets of cam roller transmission mechanisms arranged in series. All arc-shaped cams are fixed to the input shaft by flat keys and are installed in the same phase, and are synchronously driven by a single drive module. Each transmission mechanism is connected to an independent turntable, and the synchronization error of multiple turntables is ≤1 arcsecond.

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