A reverse type planetary roller screw applied to a robot

Abstract

The application provides a reverse type planetary roller screw applied to a robot and relates to the technical field of roller screws. The beneficial effects of the application are that a reverse type planetary roller screw applied to a robot is provided, a plurality of planetary follow-up nuts and an outer nut are combined to replace the design of the single nut, the length of the planetary follow-up nut can be greatly shortened, the difficulty of internal thread machining is reduced, the precision during the machining process can be more easily controlled, the error accumulation caused by the length is reduced, the machining difficulty is effectively reduced, the interference and vibration during the machining process are reduced, the machining stability is improved, and the machining cost is reduced.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of roller screws, in particular to a reverse type planetary roller screw applied to a robot. BACKGROUND

[0002] The reverse type planetary roller screw applied to a robot, as a kind of precise mechanical transmission device, plays a crucial role in the modern industrial field. It can realize efficient conversion between rotary motion and linear motion, and has become an ideal substitute for ball screws in high-load application scenarios due to its unique structure and excellent performance.

[0003] The core working principle of the reverse type planetary roller screw applied to a robot is derived from its ingenious planetary gear system design. In the running process, the rollers exhibit a unique motion mode as the planets in the planetary gear system. They not only rotate around their own axes, but also revolve along the inner cavity of the nut. This compound motion mode makes the reverse type planetary roller screw applied to a robot more stable and efficient in power transmission, and can withstand greater loads and impact forces.

[0004] The reverse type planetary roller screw applied to a robot is mainly used for humanoid robot joint driving. It converts motor rotary motion into high-precision linear displacement to drive robot limbs such as arms, legs, dexterous hands, etc. to complete stretching, bending and other actions. Compared with traditional ball screws, the reverse type design reduces the volume by 1 / 3 under the same load, meets the needs of humanoid robots for lightweight and small-sized joints, improves load capacity while reducing production costs, and ensures long-term stable operation of robots through linear contact transmission of rollers and screws, higher positioning accuracy and longer service life.

[0005] However, the reverse type planetary roller screw applied to a robot faces many challenges in the process of manufacturing. Among them, the machining of internal threads is a major difficulty. The internal threads of the reverse type planetary roller screw applied to a robot usually require a considerable length and have very high precision requirements. This is because the precision of the internal threads directly affects the transmission precision, load capacity and service life of the reverse type planetary roller screw applied to a robot. In order to meet the high precision requirements, advanced machining equipment and processes such as high-precision thread grinding machines and numerical control machining centers need to be used in the machining process. At the same time, various parameters in the machining process such as cutting speed, feed rate and cutting depth need to be strictly controlled to ensure the dimensional accuracy and surface quality of the internal threads.

[0006] The current traditional reverse planetary roller screw applied to robots on the market is designed by setting internal threads on the inner circumferential surface of the nut to realize the connection with the roller and the screw. However, this connection mode also brings a series of problems. Because a relatively long and high-precision thread needs to be processed on the inner circumferential surface of the nut, it puts forward very high requirements for the processing equipment and process. On the one hand, the processing process needs to consume a lot of time and energy, resulting in low production efficiency; on the other hand, the high-precision processing requirement greatly increases the processing difficulty, and processing errors are prone to occur, thereby reducing the yield of finished products. In addition, in order to ensure the precision of the internal thread, expensive processing equipment and detection instruments need to be used, which undoubtedly increases the production cost. SUMMARY

[0007] The application overcomes the shortcomings in the prior art and provides a reverse planetary roller screw applied to robots. The combination of a plurality of planetary follower nuts and an outer nut is used to replace the design of the single nut, so that the length of the planetary follower nut can be greatly shortened. On the one hand, it reduces the processing difficulty of the internal thread, so that the precision can be more easily controlled during the processing process, and the error accumulation caused by the length is reduced. On the other hand, the processing difficulty is effectively reduced, the interference and vibration in the processing process are reduced, the stability of the processing is improved, and the processing cost is reduced.

[0008] In order to solve the above technical problems, the application is realized by the following technical scheme:

[0009] A reverse planetary roller screw applied to robots, comprising an outer nut, a planetary follower nut is clamped in the inner part of the outer nut, the planetary follower nut comprises a plurality of planetary nuts, the plurality of planetary nuts are arranged along the length direction of the outer nut, the planetary follower nut is rotationally connected with a planetary roller assembly, and the planetary roller assembly is rotationally connected with a screw.

[0010] A plurality of rollers are arranged in the planetary roller assembly, the middle part of the roller is a threaded segment, and both ends are gear segments, the gear segments of the roller are engaged with a spur gear, the inner side of the spur gear is connected with the optical axis part of the screw, the threaded segment of the roller is connected with the threads on the inner side of the planetary nut, and the threaded segment of the roller is connected with the threads of the screw.

[0011] Further, an axial inner pin groove is arranged on the inner side of the outer nut, and an outer pin groove is arranged on the outer wall of the planetary follower nut.

[0012] The cooperation of the outer pin groove and the inner pin groove limits the circumferential rotation of the planetary follower nut relative to the outer nut.

[0013] Further, a set screw is threadedly connected with the outer nut, and the end of the set screw abuts against the planetary nut to fix the axial position of the planetary nut relative to the outer nut.

[0014] Further, the planetary roller assembly comprises a planet carrier, and the rollers are connected in a ring on the planet carrier, and the rollers are connected in a ring on the planet carrier.

[0015] Further, the planetary roller assembly comprises a planet carrier, and the rollers are connected in a ring on the planet carrier, and the rollers are connected in a ring on the planet carrier.

[0016] The axial relative position of the planetary roller assembly relative to the screw is limited between the shaft buckles.

[0017] Further, the rotation direction of the screw must be opposite to that of the roller.

[0018] The screw only moves axially without rotating, the planetary nut and the outer nut only rotate without moving axially, the roller rotates and moves axially, and the axial movement of the roller and the screw must be synchronized, at this time, the ratio of the number of teeth of the screw to the number of teeth of the roller must be equal to the ratio of the diameters of the thread circles of the screw and the roller, and the number of teeth of the planetary nut must be equal to the number of teeth of the screw.

[0019] Further, the outer slot is arranged on the outer periphery of the planetary nut.

[0020] Compared with the prior art, the beneficial effects of the present application are:

[0021] The combination of the planetary nut and the outer nut is used to replace the single nut design, so that the length of the planetary nut can be greatly shortened, the precision in the machining process is easier to control, and the error accumulation caused by the length is reduced. On the other hand, the machining difficulty is effectively reduced, the interference and vibration in the machining process are reduced, the machining stability is improved, and the machining cost is reduced. BRIEF DESCRIPTION OF DRAWINGS

[0022] The accompanying drawings are used to provide a further understanding of the present application, together with the embodiments of the present application, to explain the present application, and do not constitute a limitation to the present application, in which:

[0023] Fig. 1 is a schematic diagram of the overall appearance of the reverse planetary roller screw applied to the robot of the embodiment of the present application;

[0024] Fig. 2 is a sectional view of the reverse planetary roller screw applied to the robot of the embodiment of the present application;

[0025] Fig. 3 is a schematic diagram of the internal structure of the reverse planetary roller screw applied to the robot of the embodiment of the present application;

[0026] Fig. 4This is a schematic diagram of an explosion of a reverse planetary roller screw applied to a robot according to an embodiment of the present invention.

[0027] In the diagram: 1. Outer nut; 101. Axial inner groove; 2. Planetary follower nut; 202. Planetary nut; 2021. Outer groove; 2022. Set screw; 3. Planetary roller assembly; 301. Roller; 3011. Threaded section; 3012. Gear section; 302. Planetary carrier; 4. Lead screw; 401. Spur gear; 402. Shaft retainer. Detailed Implementation

[0028] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0029] like Figs. 1 to 4 As shown, a reverse planetary roller screw for robots includes an outer nut 1, inside which a planetary follower nut 2 is snapped. The planetary follower nut 2 includes several planetary nuts 202, which are arranged along the length of the outer nut 1. This arrangement enables the mechanism to transmit power and achieve motion conversion more stably during operation.

[0030] The planetary follower nut 2 is rotatably connected to the planetary roller assembly 3, and the planetary roller assembly 3 is rotatably connected to the lead screw 4. The inner side of the outer nut 1 is provided with an axial inner groove 101, and the outer wall of the planetary follower nut 2 is provided with an outer groove 2021. The cooperation between the outer groove 2021 and the inner groove 101 restricts the circumferential rotation of the planetary follower nut 2 relative to the outer nut 1. When the planetary follower nut 2 is installed inside the outer nut 1, the outer groove 2021 and the inner groove 101 cooperate with each other, effectively restricting the circumferential rotation of the planetary follower nut 2 relative to the outer nut 1, ensuring the stability and accuracy of the mechanism during operation.

[0031] The threaded section of the lead screw 4 is also provided with shaft retaining rings 402 at both ends; the axial relative position of the planetary roller assembly 3 relative to the lead screw 4 is restricted between the shaft retaining rings 402, thus ensuring the stability of the planetary roller assembly 3 during application.

[0032] In a reverse planetary roller screw used in a robot, a number of planetary nuts 202 are provided in the middle of the planetary follower nut 2, and the outer nut 1 is threadedly connected with a set screw 2022. The end of the set screw 2022 presses against the planetary nut 202 to fix its axial position relative to the outer nut 1.

[0033] In the reverse planetary roller screw applied to robots, the rotation direction of the screw 4 must be opposite to that of the roller 301. The screw 4 only moves axially without rotating; the planetary nut 202 and the outer nut 1 only rotate without moving axially; the roller 301 moves both axially and rotationally, and the axial movement of the roller 301 must be synchronized with that of the screw 4. The ratio of the number of teeth of the screw 4 to that of the roller 301 must be equal to the ratio of their thread circle diameters, otherwise the screw 4 and the roller 301 cannot move axially synchronously. The number of teeth of the planetary nut 202 must be equal to that of the screw 4, otherwise the speed of the displacement of the screw 4 and the rotational speed of the planetary nut 202 will not be linearly related.

[0034] The planetary roller assembly 3 is composed of a planet carrier 302 and a plurality of rollers 301. The rollers 301 are connected in a ring shape on the planet carrier 302. The middle of the roller 301 is a threaded segment 3011, and the two ends are gear segments 3012. The gear segments 3012 of the roller 301 are engaged with the spur gear 401, the inner side of the spur gear 401 is connected with the optical axis part of the screw 4, and the threaded segment 3011 of the roller 301 is threadedly connected with the inner side of the planetary nut 202. This structure design enables the roller 301 to realize efficient power transmission and motion conversion between the planetary follower nut 2 and the screw 4.

[0035] The mechanism adopts the design of multiple planetary follower nuts 2 and rollers 301, so that the load can be evenly distributed on each component. Compared with the traditional screw mechanism, its carrying capacity is significantly improved, which can meet the use requirements under high load working conditions and is suitable for the transmission system of heavy machinery equipment.

[0036] The traditional mechanism usually adopts a nut with internal threads. In the field, the nut in this paper will also be called a nut. The two names actually refer to the same structure product, and the mechanism uses a combination of several planetary follower nuts 2 and outer nuts 1 to replace the design of a single nut. This innovative design brings many benefits, the most notable of which is that the length of the planetary follower nut 2 can be greatly shortened, which can be reduced to less than half compared with a general nut.

[0037] The shortening of the length is of great significance to the machining of the internal threads of the planetary follower nut 2. On the one hand, it reduces the difficulty of internal thread machining. In the traditional long nut internal thread machining, it is difficult to ensure the accuracy of the entire thread due to the long length. However, in the mechanism, the shorter planetary follower nut 2 makes it easier to control the accuracy during machining, reducing the accumulation of errors caused by length. On the other hand, the machining difficulty is also effectively reduced. The shorter length makes the machining tool more flexible during operation, reducing interference and vibration during machining and improving the stability of machining.

[0038] Comprehensively, the design can significantly improve the machining speed of the inner thread of the planet follow-up nut 2, thereby improving the production efficiency of the whole mechanism, reducing the production cost, and providing strong support for the wide application of the mechanism in the industrial field.

[0039] Finally, it should be noted that the above is only the preferred embodiment of the present application and is not intended to limit the present application. Although the present application is described in detail with reference to the embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent replacements for some technical features, but any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A reverse-type planetary roller screw for use in robots, characterized in that, It includes an outer nut (1), and a planetary follower nut (2) is snapped into the inner part of the outer nut (1). The planetary follower nut (2) includes several planetary nuts (202), which are arranged along the length direction of the outer nut (1). The planetary follower nut (2) is rotatably connected to the planetary roller assembly (3), and the planetary roller assembly (3) is rotatably connected to the lead screw (4). The planetary roller assembly (3) is provided with several rollers (301) inside. The middle of the roller (301) is a threaded section (3011) and the two ends are gear sections (3012). The gear section (3012) of the roller (301) meshes with the spur gear (401). The inner side of the spur gear (401) is connected to the optical axis of the lead screw (4). The threaded section (3011) of the roller (301) is threadedly connected to the inner side of the planetary nut (202) and threadedly connected to the lead screw (4). The outer nut (1) has an axial inner groove (101) on its inner side, and the planetary follower nut (2) has an outer groove (2021) on its outer wall. The engagement of the outer bolt groove (2021) and the inner bolt groove (101) restricts the circumferential rotation of the planetary follower nut (2) relative to the outer nut (1); The spur gear (401) is provided at both ends of the threaded section of the lead screw (4), and the two ends of the threaded section of the lead screw (4) are also provided with shaft retaining rings (402). The axial relative position of the planetary roller assembly (3) to the lead screw (4) is restricted between the shaft retaining rings (402).

2. The reverse planetary roller screw for robots according to claim 1, characterized in that, The outer nut (1) is threaded with a set screw (2022), the end of which presses against the planetary nut (202) to fix its axial position relative to the outer nut (1).

3. The reverse planetary roller screw for robots according to claim 1 or 2, characterized in that, The planetary roller assembly (3) includes a planetary carrier (302), on which a ring-shaped roller (301) is connected. The roller (301) is rotatably connected to the planetary follower nut (2) and the lead screw (4).

4. The reverse planetary roller screw for robots according to claim 1 or 2, characterized in that, The direction of rotation of the lead screw (4) must be opposite to that of the roller (301); The lead screw (4) only moves axially and does not rotate; the planetary nut (202) and the outer nut (1) only rotate and do not move axially; the roller (301) moves both axially and rotates, and the axial movement of the roller (301) and the lead screw (4) must be synchronized. At this time, the ratio of the number of teeth of the lead screw (4) to the number of teeth of the roller (301) must be equal to the ratio of their thread pitch circle diameters, and the number of teeth of the planetary nut (202) must be equal to the number of teeth of the lead screw (4).

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