CN114623217A - An annular tooth roller screw drive mechanism - Google Patents

Abstract

The invention provides an annular tooth roller screw transmission mechanism, which includes a screw, a roller, a nut, a cage, an inner gear ring and a positioning pin. It has a plurality of annular protruding teeth and both ends are processed with straight teeth; the rollers are distributed around the screw, and the roller protruding teeth are engaged with the thread of the screw; the nut has annular concave teeth, which mesh with the roller annular protruding teeth; The ring gear is installed in the groove on the inner wall of the nut and the installation phase angle is fixed. The straight teeth of the inner ring gear mesh with the straight teeth of the roller; the cage is installed in the groove of the inner wall of the nut, and the optical axes at both ends of the roller are connected to the cage. Matching with U-shaped grooves. The invention can obtain smaller radial dimension than the standard planetary roller screw in the state of the same pitch diameter of the screw; and can use multiple sets of rollers to improve the uneven bearing characteristics of long rollers and multiple threads.

Description

An annular tooth roller screw drive mechanism

technical field

The invention belongs to the technical field of mechanical transmission, and in particular relates to a roller screw transmission mechanism, which is particularly suitable for transmission under heavy load conditions under limited installation space.

Background technique

The planetary roller screw is a precision transmission mechanism and rolling functional component that transmits power and motion through the curved surface meshing between multiple rollers, the screw and the nut. As the actuator of the electromechanical servo system, the planetary roller screw can greatly improve its power density, can replace the high-thrust hydraulic and pneumatic servo systems, and completely solve the problems of "running, running, dripping, and leaking", which is important for significantly improving the performance of mechanical equipment. It has far-reaching significance for operating efficiency and reducing maintenance costs, promoting the rapid development of all-electric intelligent equipment and promoting the development of a low-carbon and environmentally friendly economy. At present, planetary roller screws have been used in all-electric/multi-electric equipment fields such as aircraft rudder surfaces, tank height drives, ship stabilizers, six-degree-of-freedom platforms, welding robots, and precision CNC machine tool feeds. Aerospace, vehicle, petrochemical and robotics industries have broad application prospects in the fully electrified development of machinery and equipment in many military and civilian industries.

When the planetary roller screw is used to replace the high-thrust hydraulic transmission, there is a problem that the radial dimension is too large, so that it cannot be installed in the relevant mechanical equipment. This is because in a standard planetary roller screw, the screw diameter, roller diameter and nut diameter must satisfy: d _n =Nd _r and d _r =d _s /(N-2), where d _s , d _r and _dn are the pitch diameters of the screw, roller and nut, respectively, and N is the number of threads of the screw and nut. (Comprehensive Product Manual of Servo Electric Cylinders and Planetary Roller Screws[M]. Beijing: Doson Technology Development (Beijing) Co., Ltd., 2010, www.doson-inc.com; Satellite roller screws[M].Geneva: Rollvis, 2019, www.Rollvis.com). When the pitch diameter of the screw increases, the pitch diameter of the roller will increase according to the proportional relationship of d _r =d _s /(N-2), and the radial dimension of the planetary roller screw will also increase significantly. The standard planetary roller screw can reduce the roller diameter by increasing the number of screw threads N, thereby reducing the radial dimension of the mechanism. However, the number of nut threads will increase with the increase of the number of screw threads N, which will greatly increase the difficulty and cost of grinding the internal thread of the nut. At the same time, when the thread pitch is fixed, increasing the number of nut threads will increase the lead and helix angle of the corresponding thread, which will increase the inclination angle of the thread grinding wheel shaft, thereby limiting the minimum radial size and length of the nut. In addition, due to structural limitations and load-bearing requirements, the number of screw threads of standard planetary roller screws cannot be greatly increased.

In the recirculating planetary roller screw, although the pitch diameter of the screw is not proportional to the pitch diameter of the roller, the roller moves along the nut thread, and must pass through a specific structure or device to return to its original position at regular intervals. In addition, due to the difference in helix angle, the roller and the nut are always in a relative sliding state at the contact point. This makes the movement of the rollers discontinuous and inefficient during the operation of the recirculating planetary roller screw.

In addition, too many threads on a single roller will aggravate the phenomenon of uneven load distribution (Zhang Wenjie. Calculation model and method of thread load distribution of planetary roller screw pair [D]. Xi'an: Northwestern Polytechnical University Doctoral Thesis, 2017). Secondly, the larger the diameter of the roller, the more serious the uneven load distribution of the roller on the screw side and the nut side thread (Blinov D S, Morozov MI. Uneven load distribution between mating windings of roller and screw withnut of planetary roller drive [J ]. Science and Education of the Bauman MSTU, 2014, 9:1-14). This also limits the increase in the carrying capacity of the heavy-duty planetary roller screw. Finally, the existing planetary roller screw products need to simultaneously consider the phase matching with the nut thread and the spur teeth of the ring gear during the roller assembly process, which increases the complexity of the assembly.

The patent "a planetary roller screw CN201210078456.0" provides a planetary roller screw with a screw thread structure and a ring-shaped tooth structure for the rollers and nuts, which is used to reduce the axial volume of the entire device and facilitate the loading and unloading. The patent points out that the number of rollers in the planetary roller screw is one or more, generally two or more, and the limit is that the rollers do not interfere with each other at most. However, due to the common constraints of the lead angle of the screw and the ring structure of the nut, if the number of rollers and the number of screw heads do not match, the rollers and the screw will interfere with each other. For example: when the number of screw threads is 5 and the rollers are evenly distributed around the screw, if the number of rollers is greater than 2 but not equal to 5, the rollers will interfere with the screw and the assembly of the mechanism cannot be completed. The patent "A Planetary Roller Screw CN 201210078456.0" does not explain this problem. In addition, the patented structure cannot realize parallel assembly of multiple sets of rollers.

The patents "gear-driven planetary roller screw CN202010986386.3", "ring-toothed nut planetary roller screw CN 202010984767.8" and "planetary roller screw transmission mechanism CN 201210504715.1" all adopt the two ends of the nut meshing with the rollers. On the one hand, the contact section is short, which limits the maximum bearing capacity of the planetary roller screw. Secondly, the design of the roller, the screw and the nut meshing point are not in the same section of the structure, which will make the roller bear a large bending moment under heavy load conditions. Rollers are usually slender structural members that are difficult to withstand moment loads; increasing the roller diameter to increase its resistance to bending will greatly increase the outer diameter of the nut. The patent "a planetary roller screw CN202010485426.6" adopts the structure that the two ends of the roller are meshed with the middle ring teeth and the nut to improve the stress state of the roller, but if it is required to achieve the standard planetary roller on a single roller Column screw (servo electric cylinder and planetary roller screw comprehensive product manual [M]. Beijing: Daochen Technology Development (Beijing) Co., Ltd.) the same number of contact points, the roller length in this invention is the standard planetary roller 2 times the length of the rollers in the column screw. In addition, the rollers in the patent "A Planetary Roller Screw CN202010485426.6" will still be subjected to bending moment loads, which is not conducive to the structural design of small diameter rollers. The patent "a nut type gearless constant lead planetary roller screw ZL202010800383.6" belongs to the improved design of the reverse planetary roller screw structure. The diameter of the screw and the roller must meet a certain proportional relationship.

SUMMARY OF THE INVENTION

In order to overcome the deficiencies of the prior art, the present invention provides an annular tooth roller screw transmission mechanism, which can obtain a smaller radial dimension than the standard planetary roller screw under the same screw diameter state; Set of rollers to improve the uneven load bearing characteristics of long rollers with multiple threads.

The technical scheme adopted by the present invention to solve the technical problem is: an annular tooth roller screw transmission mechanism, which includes a screw, a roller, a nut, a cage, an inner gear ring and a positioning pin.

The lead screw is a multi-start external thread, the number of threads is N, and the pitch is P; the two ends of the roller are optical axes, and the middle section has a plurality of annular protruding teeth, and both ends of the annular protruding teeth are processed in the circumferential direction. There are straight teeth, and the spacing between the annular protruding teeth is equal to the screw pitch P; the rollers are distributed around the screw, and the roller protruding teeth are engaged with the screw thread. The number of rollers R must satisfy R=N/Z, where Z is positive Integer, Z=1, 2, 3...; there are annular concave teeth inside the nut, and several circumferential grooves are arranged along the axial direction; the annular concave teeth of the nut and the roller annular convex teeth are engaged with each other; the cage is provided with The annular structure of the truncated opening has a plurality of U-shaped grooves evenly distributed on the inner wall along the circumferential direction; the inner gear ring is provided with a ring structure of truncated openings, the inner wall has a number of straight teeth evenly distributed along the circumferential direction, and the outer wall is provided with radial positioning pin holes; the rollers The number of spur teeth z _r and the number of spur teeth z _n of the nut satisfy the proportional relationship of d _r /d _n =z _r /z _n , where d _r and d _n are the pitch diameters of the roller and the nut respectively; The inner gear ring is installed in the groove of the inner wall of the nut, the installation phase angle of the inner gear ring is fixed by a positioning pin, and the straight teeth of the inner gear ring mesh with the straight teeth of the roller; the cage is installed on the inner wall of the nut. In the groove, the optical axis at both ends of the roller is matched with the U-shaped groove of the cage.

Further, a plurality of rollers having the same axial position around the screw is defined as one group, and X groups are installed along the axial direction of the screw, X=1, 2, 3 . . .

Further, when there are more than 2 sets of rollers, according to the state of the external load on the nut and the lead screw, each set of rollers is designed to have different meshing clearances between the lead screw and nut, so that each set of rollers can bear the same load. .

Further, the installation interval angle of each roller in a group of rollers is equal to Z×360°/N.

Further, the inner wall of the cage is provided with a process groove between two adjacent U-shaped grooves.

The beneficial effects of the present invention are:

The annular tooth roller screw proposed by the invention has a multi-start external thread, the number of threads is N, the roller and the nut respectively have annular convex tooth and concave tooth structure; the rollers are distributed around the lead screw, and the roller convex The teeth are engaged with the screw thread, and the number of rollers R must satisfy R=N/Z, where Z is a positive integer, Z=1, 2, 3...; the installation interval angle of each roller in a group of rollers can be equal to Z×360°/N, where N is the number of screw heads, Z is a positive integer, Z=1, 2, 3…. This structure and parameter relationship can ensure that multiple rollers of the same group are in the same axial position, thereby meeting the requirement that the rollers engage with the nut and the lead screw at the same time. The beneficial effect of this structure is that there is no proportional relationship constraint between the pitch diameter d _s of the screw and the pitch diameter d _r of the roller, and there is no proportional relationship constraint of d _r =d _s /(N-2), while the pitch diameter d _n of the nut and the pitch of the roller There is no proportional relationship constraint of d _n =Nd _r between the diameters d _r , where N is the number of screw threads. The diameter of the roller can be much smaller than the diameter of the lead screw. When the diameter of the lead screw is a fixed value, the radial dimension of the entire transmission mechanism is greatly reduced. In the present invention, the nut has an annular concave tooth structure, and the problem of the inclination angle of the grinding wheel shaft does not need to be considered in the grinding process. The processing difficulty of the nut will not increase with the increase of the number of screw threads. The selection of the number of screw threads does not need to consider the influence on the diameter of the rollers, and a lead screw with a larger lead can be obtained, thereby improving the transmission speed and transmission efficiency of the transmission mechanism.

In addition, since both the roller and the nut are designed with annular teeth, there is no relative axial movement between the roller and the nut, so there is no need to go through a specific structure or device to return the roller to the original position. The ring teeth of the roller and the nut are parallel to each other, which can ensure that the theoretical meshing point of the two parts is at the tangent point of the middle diameter circle, so that the roller can perform pure rolling motion inside the nut in the present invention, and the friction between the roller and the nut is reduced. sliding between.

The invention can realize the assembly of multiple groups of rollers, and can decompose the long rollers in the original heavy-duty planetary roller screw into a plurality of short rollers for common bearing. The number of threads on a single roller can be reduced, and at the same time, each group of rollers can be designed to have different assembly clearances with the screw and nut, so that each group of rollers can bear the same load, thereby improving the bearing capacity. The middle diameter of the roller of the present invention can be much smaller than the middle diameter of the screw, which can solve the situation that the load distribution of the roller on the screw side and the nut side caused by the excessively large roller diameter is seriously uneven (Blinov D S, Morozov M I . Uneven load distribution between mating windings of roller and screw with nut of planetary rollerdrive [J]. Science and Education of the Bauman MSTU, 2014, 9:1-14).

In the present invention, the rotation of the roller around its axis does not affect the relative axial position of the roller and the nut, so that the phase matching between the roller and the nut and the roller and the ring gear does not need to be considered in the assembly process. The rollers have the same length of contact section on the screw side and the nut side, which is beneficial to improve the bearing capacity of the mechanism per unit axial length, and at the same time avoid the rollers from being subjected to excessive bending moment loads.

The invention can greatly improve the thrust-to-weight ratio of the heavy-load planetary roller screw and reduce the radial dimension of the transmission mechanism. To promote electromechanical servo system to replace high thrust hydraulic and pneumatic servo system, completely solve the problem of "running, running, dripping and leaking", improve the operation efficiency of mechanical equipment and reduce maintenance costs, promote the rapid development of all-electric intelligent equipment and promote low carbon Environmentally friendly economic development has far-reaching significance.

Description of drawings

Fig. 1 is a schematic perspective view of the structure of a ring-shaped roller screw drive mechanism;

Fig. 2 is a three-dimensional schematic diagram of a lead screw structure;

Fig. 3 is the three-dimensional schematic diagram of roller structure;

Figure 4 is a three-dimensional schematic diagram of a nut structure;

Figure 5 is a schematic plan view of the nut structure;

Figure 6 is a three-dimensional schematic diagram of the cage structure;

Figure 7 is a three-dimensional schematic diagram of the structure of the inner ring gear;

Figure 8 is a three-dimensional schematic diagram of a positioning pin structure;

Figure 9 is a schematic cross-sectional view of the meshing of the roller spur teeth and the inner ring gear;

Figure 10 is a schematic cross-sectional view of the engagement between the roller annular convex teeth and the nut annular concave teeth and the screw thread;

Figure 11 is a schematic perspective view of the structure of the annular tooth roller screw drive mechanism with 1 set of rollers;

FIG. 12 is a schematic perspective view of the structure of an annular tooth roller screw drive mechanism with three sets of rollers.

Detailed ways

The present invention will be further described below with reference to the accompanying drawings and embodiments, and the present invention includes but is not limited to the following embodiments.

The invention provides an annular tooth roller screw transmission mechanism, which comprises a screw, a roller, a nut, a cage, an inner gear ring and a positioning pin. The lead screw is a multi-start external thread, the number of threads is N, and the pitch is P; the roller has a plurality of annular protruding teeth, the spacing of the annular protruding teeth is equal to the screw pitch P, and the two ends of the annular protruding teeth are processed There are straight teeth; the rollers are distributed around the screw, the roller protrusions mesh with the screw thread, the number of rollers R must satisfy R=N/Z, where Z is a positive integer, Z=1, 2, 3… ; There is no proportional relationship constraint between the pitch diameter d _s of the screw and the pitch diameter d _r of the roller, and there is no proportional relationship constraint of d _r =d _s /(N-2); the inside of the nut has annular concave teeth, and the inside of the nut is connected with the cage and the inner The groove in which the ring gear matches; the annular concave teeth of the nut and the annular convex teeth of the rollers mesh with each other; since the rollers and the nut are designed with annular teeth, there is no d _n between the middle diameter d _n of the nut and the middle diameter d _r of the roller =Nd _r proportional relationship constraints; the cage has a U-shaped groove and a truncated opening; the inner gear ring is a thin-walled structural member with straight teeth, a positioning pin hole and a truncated opening. The number of spur teeth z _r of the roller and the number of spur teeth z _n of the nut must satisfy the proportional relationship of d _r /d _n =z _r /z _n ; the inner gear ring reduces the outer diameter through elastic deformation, and the corresponding After the groove is released, the elastic deformation returns to its original size. Then, use the positioning pin to fix the installation phase angle of the ring gear; the cage also reduces its outer diameter through elastic deformation, and then releases the elastic deformation to restore the original size after being installed in the corresponding groove inside the nut.

Further, a plurality of rollers having the same axial position around the screw is defined as 1 group, and X groups can be installed in the annular tooth roller screw, where X can be equal to 1, 2, 3 . . . The long roller in the original heavy-duty planetary roller screw is decomposed into multiple short rollers to jointly carry.

Further, when there are more than 2 sets of rollers, that is, when X≥2, according to the state of the external load on the nut and the lead screw, each set of rollers, the lead screw and the nut can be designed to have different meshing gaps, so that the Each set of rollers is subjected to the same load.

Further, the cage can be processed into a technological groove to improve its elastic deformation so as to reduce the outer diameter and fit into the nut.

Further, the installation interval angle of each roller in a group of rollers may be equal to Z×360°/N, where N is the number of screw heads, Z is a positive integer, and Z=1, 2, 3 . . .

Further, the pitch diameter of the roller can be much smaller than the pitch diameter of the lead screw; when the diameter of the lead screw is a fixed value, the radial dimension of the entire transmission mechanism is greatly reduced. The nut has a ring-shaped concave tooth structure, and there is no need to consider the inclination angle of the grinding wheel shaft during the grinding process.

As shown in FIG. 1 , an embodiment of the present invention provides an annular tooth roller screw transmission mechanism, which includes parts such as a lead screw 1 , a roller 2 , a nut 3 , a cage 4 , an inner gear 5 , and a positioning pin 6 .

As shown in FIG. 2 , in the embodiment of the present invention, the lead screw 1 is a multi-thread thread. In this embodiment, the number of threads of the lead screw 1 is N _s =20, the pitch is P = 2mm, and the pitch diameter of the lead screw 1 is 75mm. .

As shown in FIG. 3 , in the embodiment of the present invention, the middle section of the roller 2 is a plurality of annular protruding teeth 2-3, and the spacing between the annular protruding teeth 2-3 is equal to the screw pitch P=2mm; It is the optical axis 2-1; the optical axis 2-1 is matched with the U-shaped groove 4-1 in the cage 4; the two ends of the annular convex teeth 2-3 in the roller 2 are processed with roller straight teeth 2-2 ; Roller spur teeth 2-2 mesh with inner ring gear spur teeth 5-1. In this embodiment, the number of teeth of the straight roller teeth 2-2 is z _r =10, the diameter of the pitch circle of the annular roller teeth 2-3 is d _r =10mm, and the number of rollers in a set of rollers is N _r = N _s =20.

As shown in Figures 4 and 5, in the embodiment of the present invention, the nut 3 has two sets of annular concave teeth 3-3, and the spacing between the annular concave teeth 3-3 is equal to the lead screw pitch P=2mm; The inner gear mounting groove 3-2 and the cage mounting groove 3-1; the positioning pin through hole 3-4 is machined in the inner gear mounting groove 3-2; the cage mounting groove 3-1 Dismantling through holes 3-5 are processed inside. In this embodiment, the pitch circle diameter of the annular concave teeth 3-3 of the nut 3 is _dn =95mm. In this embodiment, the outer diameter of the nut 3 is 115 mm. In Rollvis products, when the screw diameter is 75mm, the minimum outer diameter of the nut is 150mm (Satelliteroller screws[M].Geneva:Rollvis,2019,www.Rollvis.com).

As shown in FIG. 6 , in the embodiment of the present invention, the cage 4 has a plurality of U-shaped grooves 4-1 evenly distributed; process grooves 4-2 are arranged in the interval of each U-shaped groove 4-1; The frame 4 has a cut-off opening 4-3 therein.

As shown in FIG. 7 , in the embodiment of the present invention, the ring gear 5 is a thin-walled structure, and the number of spur teeth 5-1 of the ring gear in this embodiment is z _n =z _r /(d _r /d _n )=95; there is a positioning pin hole 5-2 on the inner gear ring 5, and a cut-off opening 5-3 is provided.

As shown in FIG. 8 , in the embodiment of the present invention, the positioning pin 6 has a stepped structure, wherein the large end 6-1 is matched with the positioning pin hole 5-2 of the inner gear ring, and the small end 6-2 is matched with the nut positioning pin through hole 3 -4 to match.

In this embodiment, the outer diameters of the four inner gear rings 5 are reduced by elastic deformation, and then inserted into the corresponding inner gear ring gear mounting grooves 3-2 inside the nut 3, and then the elastic deformation is released to restore the original size. Thirdly, use the positioning pin 6 to match with the positioning pin hole 5-2 of the inner gear to fix the installation phase angle of the inner gear. Reduce the outer diameter of the four cages 4 through elastic deformation, install them into the corresponding cage mounting grooves 3-1 inside the nut 3, and then release the elastic deformation to restore the original size. Then, install the roller 2, so that the annular protruding teeth 2-3 of the roller 2 engage with the annular concave teeth 3-3 of the nut 3, and the straight roller teeth 2-2 engage with the spur teeth 5-1 of the ring gear , the optical axis 2-1 of the roller 2 is matched with the slot 4-3 in the cage 4 .

A total of 2 groups of 40 rollers 2 are installed in this embodiment. Finally, the axis of the screw 1 is made to coincide with the axis of the nut 3, and the front end of the thread of the screw 1 is in contact with the annular protrusion 2-3 of the roller 2. Then the lead screw is rotated, and a certain axial pressure is applied, so that the annular protrusions 2-3 of each roller 2 are engaged with the screw thread. Complete the ring roller screw assembly. Figure 9 shows a schematic cross-sectional diagram of the meshing of the roller spur teeth 2-2 and the ring gear spur teeth 5-1 after the assembly is completed. Figure 10 shows a schematic cross-sectional view of the engagement between the roller annular convex teeth 2-3 and the nut annular concave teeth 3-3 and the screw thread 1 .

In this embodiment, the pitch diameter of the lead screw 1 is 75 mm, and the outer diameter of the nut 3 is 115 mm. The outer diameter of the nut corresponding to the pitch diameter of the 75mm lead screw in Rollvis products is 150mm.

The annular tooth roller screw transmission mechanism with 1 group and 3 groups of rollers can be assembled as shown in Figure 11 and Figure 12 respectively.

The above disclosure is only a specific embodiment of the present invention, and those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Variations that can be conceived by those skilled in the art should fall within the protection scope of the present invention.

Claims (5)

1. A kind of annular tooth roller lead screw drive mechanism, including lead screw, roller, nut, cage, ring gear and locating pin, characterized by that, the said lead screw is the external screw thread of the multiple-start, the number of the threaded first is N, the pitch is P; two ends of the roller are optical axes, the middle section of the roller is provided with a plurality of annular convex teeth, straight teeth are machined at two ends of the annular convex teeth along the circumferential direction, and the distance between the annular convex teeth is equal to the screw pitch P of the screw rod; the rollers are distributed around the screw rod, the convex teeth of the rollers are meshed with the screw rod threads, and the number R of the rollers must meet the requirement that R is N/Z, wherein Z is a positive integer, and Z is 1, 2 or 3 …; the nut is internally provided with annular concave teeth, and a plurality of circumferential grooves are formed in the nut along the axial direction; the nut annular concave teeth are meshed with the roller annular convex teeth; the retainer is of an annular structure provided with a cut-off opening, and a plurality of U-shaped grooves are uniformly distributed on the inner wall of the retainer along the circumferential direction; the inner gear ring is provided with an annular structure with a cut-off opening, a plurality of straight teeth are uniformly distributed on the inner wall along the circumferential direction, and the outer wall of the inner gear ringA radial positioning pin hole is arranged; the number z of straight teeth of the roller_rAnd the number z of straight teeth of the nut_nSatisfy d_r/d_n＝z_r/z_nProportional relation of (d)_rAnd d_nThe pitch diameters of the roller and the nut are respectively; the inner gear ring is arranged in a groove on the inner wall of the nut, a positioning pin is used for fixing the installation phase angle of the inner gear ring, and the straight teeth of the inner gear ring are meshed with the straight teeth of the roller; the retainer is arranged in a groove in the inner wall of the nut, and optical axes at two ends of the roller are matched with a U-shaped groove of the retainer.

2. An annular toothed roller screw drive according to claim 1, characterized in that the rollers with the same axial position around the screw are defined as 1 group, and that X groups are mounted in the axial direction of the screw, X being 1, 2, 3 ….

3. An annular toothed roller screw drive according to claim 2, characterized in that with more than 2 groups of rollers, the different meshing clearances between the groups of rollers and the screw and nut are designed so that the groups of rollers are subjected to the same load, depending on the state of the external load to which the nut and screw are subjected.

4. An annular toothed roller screw transmission according to claim 2, characterized in that the rollers of a set are mounted at an angular interval equal to Z x 360 °/N.

5. An annular roller screw drive according to claim 1, wherein the inner cage wall is provided with a process groove between two adjacent U-shaped grooves.

Images