Standard toothless planetary roller screw

Abstract

The invention relates to a standard toothless planetary roller screw, and belongs to the technical field of roller screws, the standard toothless planetary roller screw comprises a screw rod, a nut, a planet carrier assembly and a plurality of rollers, and the periphery of the screw rod is provided with external threads; internal threads are arranged on the inner wall of the nut, and unthreaded hole parts are arranged at the two ends of the internal threads; each roller comprises a threaded part in the middle and polished shaft parts at the two ends; the thread part of the roller and the internal thread of the nut have the same screwing direction and the same lead angle; the planet carrier assembly comprises a middle retainer, and the middle retainer is provided with at least three open grooves used for assembling the pin rollers in the radial direction. By canceling nut gear ring / ring groove and pin roller gear / ring groove structures and combining a double matching mechanism of the planet carrier assembly, the machining bottleneck of a composite structure is thoroughly eliminated, the axial parallelism and the constant lead characteristic of the pin rollers are guaranteed, meanwhile, vibration noise is remarkably reduced, and high-precision and large-scale mass production is achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of roller screws, in particular to a standard toothless planetary roller screw. BACKGROUND

[0002] As a key mechanical transmission component for realizing the mutual conversion between helical motion and linear motion, the planetary roller screw is widely used in high-end numerical control equipment, servo actuation system and precision robots, etc. due to its high load capacity, long service life, fast response and wide lead range. Its structure combines the planetary gear transmission principle and the helical meshing characteristics, and forms a planetary motion pair by arranging multiple rollers circumferentially to overcome the load and speed bottleneck of the traditional ball screw.

[0003] The existing standard planetary roller screw relies on the meshing structure of the external gear at both ends of the roller and the internal gear ring of the nut to ensure the stability of the motion. However, this gear meshing structure causes the nut and the roller to need to be machined with high-precision threads and gears at the same time, forming a complex composite configuration. This double functional integration significantly increases the manufacturing difficulty - the superposition of the form and position tolerances of the gear and the thread makes it difficult to control the precision, the machining efficiency of high-hardness materials is low, and ultimately results in high production cost, poor consistency of mass production, and the gear meshing is prone to induce vibration and noise. Limited by the above manufacturing bottlenecks, the planetary roller screw has not been able to achieve high-precision, large-scale, commercial mass production breakthroughs in the world for more than 70 years. There is a growing demand for high-performance planetary roller screws in key fields such as current numerical control machine tools, electrified engineering machinery, new energy vehicles (braking / steering / suspension systems), semiconductor equipment, etc. The existing technology cannot meet market supply, making this product a focus area of global high-end manufacturing competition.

[0004] To simplify the structure, some schemes try to cancel the gear structure and use the cooperation of the ring groove at both ends of the roller and the internal ring tooth of the nut to replace the meshing function. However, practice shows that the ring groove configuration has limited effect on the axial parallel constraint of the roller, and the roller and the nut still need to be machined with a composite structure of threads and ring grooves, which does not fundamentally solve the problems of precision control difficulty and high cost, and still cannot meet the economic mass production demand. SUMMARY

[0005] In order to completely simplify the structure of the core components, effectively maintain the axial positioning accuracy of the roller, and realize the unification of high performance and mass production economy, the present application provides a standard toothless planetary roller screw.

[0006] The standard toothless planetary roller screw provided by the present application adopts the following technical scheme: A standard toothless planetary roller screw, comprising a screw rod, a nut, a planetary carrier assembly and a plurality of rollers; The outer periphery of the screw rod is provided with external threads; The nut is sleeved on the outside of the screw rod, and the inner wall of the nut is provided with an internal thread, and the two ends of the internal thread are provided with light hole portions; The roller comprises a middle threaded portion and two light shaft portions at the two ends, and the threaded portion is simultaneously engaged with the external thread of the screw rod and the internal thread of the nut; The threaded portion of the roller and the internal thread of the nut have the same screwing direction and equal helix angles; The planetary carrier assembly comprises a middle retainer, and the middle retainer is provided with at least three open slots for radially assembling the rollers; The two end light hole portions of the internal thread are each provided with a limiting piece, and each of the limiting pieces and the planetary carrier assembly is provided with a plane bearing.

[0007] By adopting the above technical scheme, the internal wall structure of the nut is simplified into a combination of a middle internal thread area and two end light hole portions, and the roller only retains a threaded portion and a light shaft portion, thereby completely eliminating the precision machining bottleneck of the traditional composite structure (gear, gear ring and ring groove, ring tooth structure), reducing the manufacturing difficulty and production cost, and being conducive to meeting the large-scale production demand. The axial assembly limitation of the traditional perforated retainer is broken through by the radial open slots on the middle retainer, so that the roller can be directly radially assembled into the open slots, avoiding the axial insertion due to the equal helix angles of the roller and the nut. The threaded portion of the roller and the internal thread of the nut have the same screwing direction and equal helix angles, which facilitates the roller to only make planetary rotary motion relative to the nut without axial displacement, that is, the threaded engagement of the nut and the roller axially restricts the roller, thereby ensuring the parallelism and constant lead characteristics of the roller, significantly reducing the comprehensive difficulty of each component, reducing vibration and noise, and providing a structural basis for large-scale production.

[0008] Optionally, one side of the plane bearing is a shaft piece, and the other side is a seat piece, the shaft piece is coaxially fixed with the nut, and the seat piece is gap-fitted with the corresponding light hole portion.

[0009] Optionally, the limiting piece comprises a limiting shaft sleeve and a limiting gland, the limiting shaft sleeve is threadedly sleeved on the screw rod, and the limiting gland is detachably fixed to the outer end of the corresponding light hole portion and used to press the limiting shaft sleeve against the shaft piece of the plane bearing.

[0010] By adopting the above technical scheme, only the limiting gland needs to be disassembled during maintenance to release the limiting shaft sleeve, without disassembling the screw rod or the planetary carrier assembly, thereby greatly shortening the maintenance path. In addition, the mechanical pressing of the limiting gland on the shaft piece forms a rigid stop surface, and the limiting gland and the limiting shaft sleeve cooperatively provide sealing protection for the plane bearing to prevent external contaminants from invading the friction interface.

[0011] Optionally, the planetary carrier assembly further comprises end covers arranged at the two ends of the middle retainer, and the end covers are provided with positioning holes gap-fitted with the light shaft portions of the rollers.

[0012] Optionally, the intermediate holder is arranged in a cage shape, and two end covers are respectively fixed to the axial two ends of the intermediate holder, and the positioning holes on each end cover are arranged in position corresponding to the open slots.

[0013] By adopting the above technical solution, the cage-shaped intermediate holder and the end covers at both ends are arranged separately, a stable planetary motion cavity is constructed, the overall rigidity of the planetary carrier assembly is improved, the risk of instability of planetary motion is inhibited, the reliability of the planetary carrier assembly and the roller in the overall revolution motion and the self-rotation motion of the roller is ensured, and the coaxial operation precision of the nut and the planetary carrier assembly is ensured. The double-end cover symmetrically distributes the radial load to prevent single-side eccentric wear; the positioning holes and the open slots are strictly corresponding in position to ensure that the space phases of the rollers are synchronized and the torque fluctuation of the planetary motion is eliminated. In addition, the detachable end cover design facilitates the maintenance and replacement of the rollers, and improves the maintainability of the product.

[0014] Optionally, the inner wall of the nut is gap-fitted with the outer circumferential surface of the corresponding end cover.

[0015] By adopting the above technical solution, the two end hole parts of the nut are gap-fitted with the outer circle of the end cover. This design eliminates the traditional inner gear ring, eliminates the interference assembly required by the traditional inner gear ring, eliminates the positioning pin hole, eliminates the installation positioning pin, eliminates the high-precision consistency processing of the two end holes, and eliminates the precise positioning process of the inner gear ring, and the production efficiency is significantly improved.

[0016] Optionally, one end of the intermediate holder close to the end cover is provided with a first positioning structure, and one end of the end cover close to the intermediate holder is provided with a second positioning structure matched with the first positioning structure.

[0017] Optionally, the open slots are uniformly distributed along the circumference of the intermediate holder, and the openings of the open slots are arranged towards the radial inner side or the radial outer side, and the slot walls of the open slots are gap-fitted with the surface of the optical axis part of the roller.

[0018] By adopting the above technical solution, the circumferentially uniformly distributed open slots are gap-fitted with the optical axis part of the roller, the slot walls of the open slots and the optical axis part are gap-controlled to control the deflection amplitude of the roller, and the radial precise positioning of the roller is realized to provide protection for the rapid and accurate installation of the end covers at both ends.

[0019] Optionally, the end cover is fixedly connected with the intermediate holder through a pin or a screw.

[0020] By adopting the above technical solution, the pin or the screw mechanically connects to provide reliable structural rigidity. Compared with welding / riveting, the detachable connection allows the assembly to compensate for thermal deformation, prevents the planetary carrier assembly from deforming during high-temperature operation, standardizes the fasteners to reduce manufacturing costs, and allows the fasteners to be replaced after damage, reducing the overall scrap rate and facilitating long-term use in industrial environments.

[0021] Optionally, a wear-resistant sleeve is arranged between the optical axis part of the roller and the hole wall of the positioning hole.

[0022] By adopting the above technical scheme, the wear-resistant sleeve intervenes in the cooperation interface between the optical axis part and the positioning hole, converts metal friction into composite interface friction, significantly reduces the friction coefficient, and improves the stability of the screw at low speed. In addition, the wear-resistant sleeve can be replaced alone as a consumable, avoiding the overall scrapping of the end cover and reducing maintenance costs; and replacing the wear-resistant sleeve of different materials can adapt to lubricated / oil-free working conditions, expanding the application scenario adaptability.

[0023] In summary, the present application has the following beneficial technical effects: 1. By simplifying the nut inner wall structure into a combination of a middle inner thread area and two end light hole parts, and the roller only retaining a thread part and an optical axis part, the precision machining bottleneck of the traditional composite structure (gear, gear ring, and ring groove, ring tooth structure) is completely eliminated, the manufacturing difficulty and production cost are reduced, which is conducive to meeting the large-scale production demand; the radial opening slot on the inner side of the intermediate retainer breaks through the axial assembly limitation of the traditional perforated retainer, so that the roller can be directly radially assembled into the opening slot, avoiding the axial insertion due to the equal helix angle of the roller and the nut; the thread part of the roller and the inner thread of the nut have the same rotation direction and equal helix angle, which facilitates the planetary rotation of the roller relative to the nut without axial displacement, that is, the thread engagement of the nut and the roller axially restricts the roller, while ensuring the parallelism and constant pitch characteristics of the roller, significantly reducing the overall difficulty of each component, reducing vibration and noise, and providing a structural basis for large-scale production.

[0024] 2. By adding a limiting piece at the two light hole parts, the axial relative displacement between the nut and the planetary carrier assembly is effectively solved, and the axial movement risk of the planetary carrier assembly is effectively inhibited. However, the introduction of the limiting piece forms a rotating friction pair between the nut and the end cover, and by the intervention of the plane bearing, the direct friction between the limiting piece and the end cover is converted into rolling friction inside the plane bearing, significantly reducing the rotating wear. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 is a schematic diagram of the overall structure of a standard type toothless planetary roller screw of embodiment 1 of the present application, wherein the nut has been cut.

[0026] Figure 2 is an exploded view of the overall structure of embodiment 1 of the present application.

[0027] Figure 3 is an exploded view of the first positioning structure, the second positioning structure, and the wear-resistant sleeve in embodiment 1 of the present application.

[0028] Figure 4 is a schematic diagram of the structure of the limiting piece and the plane bearing in embodiment 2 of the present application.

[0029] Figure 5 is Figure 4 is a partial enlarged view of A in FIG. 1.

[0030] Reference signs: 1, lead screw; 11, external thread; 2, roller; 21, threaded portion; 22, light shaft portion; 3, nut; 31, internal thread; 32, light hole portion; 4, planetary carrier assembly; 41, intermediate retainer; 411, open slot; 412, first positioning structure; 42, end cover; 421, positioning hole; 422, second positioning structure; 5, pin or screw; 6, wear sleeve; 7, limiting member; 71, limiting shaft sleeve; 72, limiting gland; 8, plane bearing; 81, shaft piece; 82, seat piece. DETAILED DESCRIPTION

[0031] The following will be combined Figures 1-3 to make a further detailed description of the present application.

[0032] Example 1 The present application discloses a standard type toothless planetary roller lead screw. Referring to Figure 1 A standard type toothless planetary roller lead screw, comprising a lead screw 1, a roller 2 and a nut 3 arranged in sequence from inside to outside, wherein the roller 2 is provided in plurality, and the plurality of rollers 2 are distributed in a circumferential array on the outside of the lead screw 1; the axial direction of the lead screw 1 is the same as that of the nut 3, and the axial direction of each roller 2 is parallel to that of the lead screw 1.

[0033] Referring to Figure 1 and Figure 2 , the outer periphery of the lead screw 1 is provided with external threads 11, the inner wall of the nut 3 is provided with internal threads 31, and the two ends of the internal threads 31 are provided with light hole portions 32. The roller 2 comprises a threaded portion 21 in the middle and light shaft portions 22 integrally formed on both ends of the threaded portion 21, the threaded portion 21 is simultaneously engaged with the external threads 11 of the lead screw 1 and the internal threads 31 of the nut 3, the threaded portion 21 of the roller 2 and the internal threads 31 of the nut 3 are the same in rotation direction and equal in helix angle, and the threaded portion 21 of the roller 2 and the internal threads 31 of the nut 3 and the external threads 11 of the lead screw 1 are equal in pitch.

[0034] Referring to Figure 1 and Figure 2 , in order to avoid the possibility of roller 2 deviation or torsion during use, a planetary carrier assembly 4 is provided between the lead screw 1 and the nut 3, the planetary carrier assembly 4 at least comprises an intermediate retainer 41, in order to further ensure the stability of the movement of the roller 2, the planetary carrier assembly further comprises end covers 42 provided on both ends of the intermediate retainer 41, and at least one of the end covers 42 is detachably connected with the intermediate retainer 41, the inner side of the intermediate retainer 41 is provided with at least three open slots 411 for radially assembling the roller 2, the open slots 411 are arranged in U shape, and the end covers 42 are provided with positioning holes 421 which are in clearance fit with the light shaft portions 22 of the rollers 2.

[0035] The application simplifies the inner wall structure of the nut 3 to a combination of the middle inner thread 31 area and the two end light hole parts 32, and the roller 2 only retains the thread part 21 and the light axis part 22, completely eliminates the precision machining bottleneck of the traditional composite structure (gear, gear ring and ring groove, ring tooth structure), reduces the manufacturing difficulty and production cost, and is conducive to meeting the large-scale production demand; the radial opening slot 411 on the inner side of the middle retainer 41 breaks through the axial assembly limitation of the traditional perforated retainer, so that the roller 2 can be directly radially installed in the opening slot 411, avoiding the axial insertion due to the equal helix angle of the roller 2 and the nut 3; in combination with the radial constraint of the positioning hole 421 of the end cover 42 to the light axis part 22 of the roller 2, the thread part 21 of the roller 2 and the inner thread 31 of the nut 3 have the same rotation direction and equal helix angle, and the roller 2 can only make planetary rotary motion relative to the nut 3 without axial displacement, that is, the thread engagement of the nut 3 and the roller 2 generates axial constraint to the roller 2, and the double cooperation mechanism ensures the parallelism and constant pitch characteristics of the roller 2, significantly reduces the comprehensive difficulty of each part, reduces vibration and noise, and provides a structural basis for large-scale production.

[0036] Referring to Figure 1 and Figure 2 , the inner wall of the nut 3 is gap fitted with the outer peripheral surface of the corresponding end cover 42, which eliminates the traditional inner gear ring, eliminates the interference assembly required by the traditional inner gear ring, eliminates the positioning pin hole, eliminates the installation of the positioning pin, eliminates the high-precision consistency machining of the two end holes of the nut 3, eliminates the precise positioning process of the inner gear ring, and significantly improves the production efficiency.

[0037] Referring to Figure 2 and Figure 3, the intermediate holder 41 is arranged in a cage shape, two end covers 42 are respectively fixed to the axial two ends of the intermediate holder 41, and the positioning holes 421 on each end cover 42 are arranged in position corresponding to the open slots 411. The intermediate holder 41 is provided with a first positioning structure 412 at one end close to the end cover 42, and the end cover 42 is provided with a second positioning structure 422 at one end close to the intermediate holder 41. In this embodiment 1, the first positioning structure 412 is a positioning surface, and the second positioning structure 422 is a stop groove matched with the positioning surface. In this way, the cage-shaped intermediate holder 41 and the two end covers 42 are arranged separately, a stable planetary motion cavity is constructed, the overall rigidity of the planetary carrier assembly 4 is improved, the risk of instability of planetary motion is suppressed, the reliability of the overall revolution of the planetary carrier assembly 4 together with the rollers 2 and the rotation of the rollers 2 is ensured, and the coaxial operation accuracy of the nut 3 and the planetary carrier assembly 4 is ensured. The double-end cover 42 symmetrically distributes the radial load to prevent one-sided eccentric wear; the positioning holes 421 and the open slots 411 are strictly corresponding in position, ensuring that the spatial phases of the rollers 2 are synchronized, and eliminating the torque fluctuation of the planetary motion. In addition, the detachable end cover 42 design facilitates the maintenance and replacement of the rollers 2, and improves the maintainability of the product.

[0038] Referring to Figure 2 and Figure 3 , the open slots 411 are uniformly distributed along the circumference of the intermediate holder 41, and the openings of the open slots 411 are arranged towards the radial inner side or the radial outer side, and the slot walls of the open slots 411 are in clearance fit with the surface of the optical axis part 22 of the roller 2. In this way, the circumferentially uniformly distributed open slots 411 are in clearance fit with the optical axis part 22 of the roller 2, the clearance control between the slot walls of the open slots 411 and the optical axis part 22 controls the deflection amplitude of the roller 2, and the radial precise positioning of the roller 2 is realized, providing a guarantee for the rapid and accurate installation of the end covers 42 at both ends.

[0039] Referring to Figure 2 and Figure 3 , the end cover 42 is fixedly connected with the intermediate holder 41 through a pin or a screw 5, facilitating the disassembly and replacement of the rollers 2 and the planetary carrier assembly 4, reducing the overall scrap rate, and facilitating the adaptation to the long-term use requirements in industrial environments.

[0040] Referring to Figure 2 and Figure 3 , a wear-resistant sleeve 6 is arranged between the optical axis part 22 of the roller 2 and the hole wall of the positioning hole 421, the wear-resistant sleeve 6 intervenes in the fitting interface between the optical axis part 22 and the positioning hole 421, converts metal friction into composite interface friction, significantly reduces the friction coefficient, and improves the stability of the screw at low speed. In addition, the wear-resistant sleeve 6 as a consumable can be replaced alone, avoiding the overall scrap of the end cover 42 and reducing the maintenance cost; and replacing the wear-resistant sleeve 6 made of different materials can adapt to lubricated / oil-free working conditions, expanding the application scene adaptability.

[0041] The embodiment 1 of the application is a standard type toothless planetary roller screw assembly method, which adopts the following assembly steps: S1, nut 3 pre-positioning: placing the nut 3 in the assembly tool to ensure that it is in a horizontal state in the axial direction; S2, intermediate retainer 41 installation: axially inserting the intermediate retainer 41 into the inner side of the nut 3 along the horizontal direction; S3, radial installation of roller 2: taking the roller 2 one by one, aligning the light axis part 22 of the roller 2 with the opening groove 411 of the intermediate retainer 41, and sinking the light axis part 22 at both ends of the roller 2 into the corresponding opening groove 411 along the vertical direction (radial direction) of the inner ring of the intermediate retainer 41, repeating the operation to uniformly distribute all the rollers 2 in the circumferential direction of the intermediate retainer 41, and making the threaded part 21 of the roller 2 engage with the internal thread 31 of the nut 3; S4, axial closing of end cover 42: taking the end cover 42 one by one, respectively pushing it from both sides of the intermediate retainer 41 in the axial direction, and aligning the positioning hole 421 of the end cover 42 with the light axis part 22 of the corresponding end of the roller 2; gently pushing the end cover 42 until the light axis part 22 of all the rollers 2 is completely inserted into the positioning hole 421 to form a clearance fit, the first positioning structure 412 of the intermediate retainer 41 engages with the second positioning structure 422 on the end cover 42, and at the same time, the outer periphery of the end cover 42 forms a clearance fit with the light hole part 32 of the nut 3; S5, locking of planetary carrier assembly 4: using pins or screws 5 to tightly fix the end cover 42 at both ends of the intermediate retainer 41 respectively to ensure the rigid connection of the planetary carrier assembly 4; S6, insertion of screw rod 1 into planetary carrier assembly 4: inserting the screw rod 1 into the planetary carrier assembly 4 along the axial direction and making the external thread 11 of the screw rod 1 engage with the threaded part 21 of the roller 2 in place, which completes the assembly of the standard type toothless planetary roller screw.

[0042] The implementation principle of the standard toothless planetary roller screw of the embodiment 1 of the present application is as follows: the present application simplifies the inner wall structure of the nut 3 into a combination structure of the middle inner thread 31 and the two end light hole portions 32, and the roller 2 only retains the threaded portion 21 and the light shaft portion 22, completely eliminates the precision machining bottleneck of the traditional composite structure (gear, gear ring and ring groove, ring tooth structure), reduces the manufacturing difficulty and production cost, and is beneficial to meet the large-scale mass production demand; the radial opening slot 411 on the middle retainer 41 breaks through the axial assembly limitation of the traditional perforated retainer, so that the roller 2 can be directly radially assembled into the opening slot 411, avoiding the axial insertion due to the equal helix angle of the roller 2 and the nut 3; in combination with the radial constraint of the positioning hole 421 of the end cover 42 to the light shaft portion 22 of the roller 2, the threaded portion 21 of the roller 2 and the inner thread 31 of the nut 3 have the same rotation direction and equal helix angle, and the roller 2 can only make planetary rotation relative to the nut 3 without axial displacement, that is, the thread engagement of the nut 3 and the roller 2 generates axial constraint to the roller 2, the double cooperation mechanism not only guarantees the parallelism and constant pitch characteristics of the roller 2, but also significantly reduces the comprehensive difficulty of each component, reduces vibration noise, and provides a structural basis for large-scale mass production.

[0043] Embodiment 2 The embodiment 2 of the present application discloses a standard toothless planetary roller screw. Figure 4 and Figure 5 The difference between the embodiment 2 and the embodiment 1 is that the two end light hole portions 32 of the inner thread 31 are each provided with a limiting piece 7, and a plane bearing 8 is arranged in abutment between the limiting piece 7 and the adjacent end cover 42. One side of the plane bearing 8 is a shaft piece 81, and the other side is a seat piece 82. The shaft piece 8 is coaxially fixed with the nut 3, and the seat piece 82 is in clearance fit with the corresponding light hole portion 32.

[0044] The embodiment 2 adds the limiting piece 7 at the two light hole portions 32, which effectively solves the problem of axial relative displacement between the nut 3 and the planetary carrier assembly 4, and effectively suppresses the risk of axial movement of the planetary carrier assembly 4. However, the introduction of the limiting piece 7 causes the nut 3 and the end cover 42 to form a rotating friction pair. Through the intervention of the plane bearing 8, the direct friction between the limiting piece 7 and the end cover 42 is converted into rolling friction inside the plane bearing 8, which significantly reduces the rotating wear.

[0045] Referring to Figure 5The limiting member 7 comprises a limiting shaft sleeve 71 and a limiting gland 72. The limiting shaft sleeve 71 is threadedly sleeved on the screw rod 1. The limiting gland 72 is detachably fixed to the outer end of the corresponding light hole portion 32 by thread connection, and is used to press the limiting shaft sleeve 71 against the shaft sheet 81 of the plane bearing 8. Thus, when the screw rod is maintained, the limiting shaft sleeve 71 can be released by only disassembling the limiting gland 72, without disassembling the screw rod 1 or the planet carrier assembly 4, so that the maintenance path is greatly shortened. In addition, the mechanical pressing of the limiting gland 72 on the shaft sheet 81 forms a rigid stop surface, and the limiting gland 72 cooperates with the limiting shaft sleeve 71 to provide sealing protection for the plane bearing 8, so as to prevent external contaminants from invading the friction interface.

[0046] It is worth noting that, due to the micron-level manufacturing tolerances (such as thread cumulative error, roller 2 length deviation, end cover 42 parallelism, etc.) of the screw rod 1, the roller 2, the planet carrier assembly 4 and other components, the limiting gland 72 is detachably fixed to the outer end of the corresponding light hole portion 32 by thread connection, and the axial pre-tightening force of the plane bearing 8 can be adjusted by tightening / loosening operation of the limiting gland 72, so as to realize dynamic compensation of the above-mentioned tolerances.

[0047] When the screw rod is applied to high-precision positioning (such as a numerical control machine tool feeding system), large load or impact load (such as an engineering machinery actuator), vibration noise suppression occasions and other working conditions, the limiting gland 72 can be properly tightened to increase the axial pre-tightening force of the plane bearing 8, eliminate the gap between the plane bearing 8 and the end cover 42, and then limit the axial degree of freedom of the planet carrier assembly 4, so as to avoid micro-movement caused by tolerances. When the limiting gland 72 is properly tightened, the friction resistance between the screw rod 1 and the roller 2 increases slightly, and the overall power consumption of the screw rod increases slightly.

[0048] When the screw rod is applied to high-speed light-load transmission (such as a robot joint), occasions sensitive to motion smoothness (such as medical equipment), batch components with large cumulative tolerances and other working conditions, the limiting gland 72 can be properly loosened to reduce the axial pre-tightening force of the plane bearing 8, release the pressing gap of the plane bearing 8, and then allow micro-axial accommodation caused by tolerances, so as to avoid forced extrusion. When the limiting gland 72 is properly loosened, although part of the axial rigidity is sacrificed, the overall transmission resistance of the screw rod is significantly reduced, and the motion smoothness is improved.

[0049] The above are preferred embodiments of the present application, and do not limit the protection scope of the present application, so that: any equivalent changes made according to the structure, shape, principle of the present application should be covered within the protection scope of the present application.

Claims

1. A standard toothless planetary roller screw, comprising a screw (1), a nut (3), a planetary carrier assembly (4) and a plurality of rollers (2), characterized in that: The outer circumference of the screw rod (1) is provided with an external thread (11); The nut (3) is sleeved on the outside of the screw rod (1), and an internal thread (31) is provided on the inner wall of the nut. Both ends of the internal thread (31) are provided with light holes (32). The roller (2) comprises a threaded portion (21) in the middle and optical axis portions (22) at both ends, wherein the threaded portion (21) is engaged with the external thread (11) of the screw rod (1) and the internal thread (31) of the nut (3) at the same time; The threaded portion (21) of the roller (2) and the internal thread (31) of the nut (3) have the same direction of rotation and the same helix angle; The planetary carrier assembly (4) comprises an intermediate retaining frame (41), and the intermediate retaining frame (41) is provided with at least three opening grooves (411) for radially assembling rollers (2); The light hole portions (32) at both ends of the internal thread (31) are both provided with limiting members (7), and a plane bearing (8) is provided between each limiting member (7) and the planetary frame assembly (4).

2. A standard toothless planetary roller screw according to claim 1, characterized in that: One side of the plane bearing (8) is a shaft piece (81), and the other side is a seat piece (82). The shaft piece (81) is coaxially fixed with the nut (3), and the seat piece (82) is clearance-matched with the corresponding light hole portion (32).

3. A standard toothless planetary roller screw according to claim 1, characterized in that: The limiting member (7) comprises a limiting sleeve (71) and a limiting pressure cover (72), wherein the limiting sleeve (71) is threadedly sleeved on the screw rod (1), and the limiting pressure cover (72) is detachably fixed to the outer end of the corresponding light hole portion (32) and is used to press the limiting sleeve (72) onto the shaft (81) of the plane bearing (8).

4. A standard toothless planetary roller screw according to claim 1, characterized in that: The planetary carrier assembly (4) further comprises end covers (42) provided at both ends of the intermediate retaining frame (41), and the end covers (42) are provided with positioning holes (421) which are clearance-matched with the optical axis portion (22) of the roller (2).

5. A standard toothless planetary roller screw according to claim 4, characterized in that: The intermediate retainer (41) is arranged in a cage shape, and the two end covers (42) are respectively fixed to the axial ends of the intermediate retainer (41), and the positioning holes (421) on each end cover (42) are arranged correspondingly to the positions of the opening slots (411).

6. A standard toothless planetary roller screw according to claim 4, characterized in that: The light holes (32) at both ends of the inner wall of the nut (3) are clearance-matched with the outer peripheral surface of the corresponding end cover (42).

7. A standard toothless planetary roller screw according to claim 5, characterized in that: A first positioning structure (412) is provided at one end of the intermediate retainer (41) close to the end cover (42), and a second positioning structure (422) adapted to the first positioning structure (412) is provided at one end of the end cover (42) close to the intermediate retainer (41).

8. A standard toothless planetary roller screw according to claim 5, characterized in that: The opening grooves (411) are evenly distributed along the circumference of the intermediate retaining frame (41), and the openings of the opening grooves (411) are arranged toward the radial inside or the radial outside, and the groove walls of the opening grooves (411) are clearance-matched with the surface of the optical axis portion (22) of the roller (2).

9. A standard toothless planetary roller screw according to claim 4, characterized in that: The end cover (42) is fixedly connected to the intermediate retaining frame (41) via pins or screws (5).

10. A standard toothless planetary roller screw according to claim 1, characterized in that: A wear-resistant sleeve (6) is provided between the optical axis portion (22) of the roller (2) and the hole wall of the positioning hole (421).

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