Thread form angle optimization design method for planetary roller screw pair

Abstract

The present application relates to a kind of thread form angle optimization design method of planetary roller screw pair, it is related to planetary roller screw technical field, the method includes: according to the thread parameters of planetary roller screw pair, the standard thread form three-dimensional model of screw, roller, nut is drawn in three-dimensional software;In the simulation module of three-dimensional software, the meshing analysis of the partial thread section of screw or nut and roller is carried out;Based on the meshing situation of the partial thread section of first screw and first roller in standard formula structure or the meshing situation of the partial thread section of second nut and second roller in reverse formula structure, adjust the thread form angle numerical value of first screw or second nut, so that first roller and first screw or second nut and second roller are not interfered with the meshing under the premise, realize the optimization of mutual meshing position.The design method is by optimizing the thread form angle numerical value of screw or nut, solve the problem of poor thread meshing, and improve carrying capacity and transmission efficiency, reduce thread wear, improve service life.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of planetary roller screw design, in particular to a thread profile angle optimization design method of a planetary roller screw pair. BACKGROUND

[0002] The planetary roller screw is a new type of transmission device that can convert rotary motion into linear motion. Because the planetary roller screw has higher impact resistance than the traditional ball screw, and the planetary roller screw can have higher rotational speed and rotational acceleration, it is widely used in precision instruments, weapons, industrial robots, aerospace and other fields.

[0003] The Chinese invention patent with publication number CN113987717B discloses a planetary roller screw tolerance optimization design method. Based on the structure and transmission principle of the planetary roller screw, the main error factors affecting the transmission accuracy of the planetary roller screw during transmission are determined. Based on the main error factors, a mathematical model is constructed with the stroke accuracy and axial clearance as the objective function, and the constraint conditions of the optimization target are determined. Sensitivity analysis is performed on the influence of part design parameters on the stroke accuracy and axial clearance of the planetary roller screw. The machining difficulty of each part is determined using the analytic hierarchy process based on triangular fuzzy numbers. The geometric mean is used to construct the weight coefficient, and the weight expression of each design parameter is established to distribute the tolerance of the planetary roller screw. The fmincon algorithm is used to optimize the fitness function of the axial clearance and output the results. The planetary roller screw tolerance optimization design method can design reasonable part size tolerance values under the premise of meeting the corresponding technical indicators.

[0004] However, the above-mentioned tolerance optimization design method needs to establish the thread surface equation of the screw, roller and nut, and the analytical calculation process is complicated and complex. The theoretical calculation process is quite complex, which is not conducive to actual production operation adjustment. Moreover, it only involves the tolerance design method of the thread pitch diameter, pitch and coaxiality, and does not involve the optimization of the thread profile angle value.

[0005] In addition, the existing planetary roller screw pair parameter design and optimization problem is still at the basic stage, the target is not clear, and the meshing deviation between the screw, roller and nut is ignored, which affects the life of the planetary roller screw pair carrying capacity, making the optimization result inaccurate.

[0006] At the present stage, the three core thread parts of the planetary roller screw pair, i.e., the screw, the roller and the nut, have a symmetrical thread angle with both left and right flank angles of 45°. Due to the inconsistent thread angles of the three parts, the design of the three parts with a 45° thread angle cannot ensure that the roller thread is kept close to the pitch circle when meshing with the screw or the nut, but is kept close to the thread top, thereby increasing the risk of fatigue fracture, thread wear, transmission efficiency, service life and safety factor and other disadvantages. SUMMARY

[0007] Therefore, the purpose of the present application is to overcome the technical problem that the planetary roller screw tolerance optimization design method in the background art ignores the influence of the meshing position deviation among the screw, the roller and the nut on the carrying capacity, thread wear, transmission efficiency, service life and the like, and to provide a thread angle optimization design method for a planetary roller screw pair.

[0008] To solve the above problems, the first purpose of the present application is to provide a thread angle optimization design method for a planetary roller screw pair, which comprises the following steps:

[0009] S1: drawing a standard thread three-dimensional model of the screw, the roller and the nut according to the thread parameters of the planetary roller screw pair through a three-dimensional software;

[0010] The planetary roller screw pair comprises a standard planetary roller screw pair structure and a reverse planetary roller screw pair structure.

[0011] S2: performing meshing analysis on the partial thread segments of the screw or the nut and the roller in the simulation module of the three-dimensional software;

[0012] The simulation module comprises an interference checking function command, and the determination parameter of the interference checking function command is set to be less than 0.000001 mm 3 ;

[0013] S3: based on the meshing condition of the partial thread segments of the first screw and the first roller in the standard new type planetary roller screw pair structure, adjusting the thread angle value of the first screw to realize the optimization of the mutual meshing position of the first screw and the first roller under the premise of non-interference meshing; or

[0014] based on the meshing condition of the partial thread segments of the second nut and the second roller in the reverse planetary roller screw pair structure, adjusting the thread angle value of the second nut to realize the optimization of the mutual meshing position of the second nut and the second roller under the premise of non-interference meshing.

[0015] Optionally, in step S1, the three-dimensional software is any one of Solidwork, Creo and CATIA.

[0016] Optionally, the standard planetary roller screw pair structure comprises a first nut, a first right gear ring, a first cage, the first screw, a first left gear ring, n first rollers, two locking screws and eight pins.

[0017] The first screw is axially horizontally placed; the first cage is sleeved on the outer wall of the first screw; n first rollers are evenly embedded in the first cage in a circumferential direction, and each of the n first rollers is arranged in parallel with the axis of the first screw and threadedly cooperates with the first screw; the first nut is sleeved on the outer wall of the first cage; the first left gear ring and the first right gear ring are arranged on the inner wall of the first nut and sleeved on the outer wall of the n first rollers.

[0018] The first left gear ring is correspondingly arranged at the left axial end of the first roller; the first right gear ring is correspondingly arranged at the right axial end of the first roller.

[0019] The first left gear ring and the first right gear ring are fixedly connected with the first nut by one locking screw and four pins respectively; n is a positive integer.

[0020] Optionally, the pitch diameter of the first roller and the first nut is drawn according to a theoretical pitch diameter value, the tooth profile angle of the first roller and the first nut is symmetrically drawn at 45 degrees, the thread angle of the first roller and the first nut is the same, and the tooth profile angle of the first screw is symmetrically drawn at a corrected angle.

[0021] Optionally, the reverse planetary roller screw pair structure comprises the second nut, a second screw moving linearly relative to the second nut, and a plurality of second rollers arranged between the second nut and the second screw.

[0022] The outer wall of the second screw is provided with screw threads and screw gears on both sides of the screw threads; the middle part of the second roller is provided with a single-thread screw thread matched with the screw threads, and both ends of the second roller are provided with roller gears matched with the screw gears; the inner wall of the second nut is provided with nut threads matched with the single-thread screw thread, and the screw threads and the nut threads are both multi-threaded.

[0023] The second screw is provided with a second cage, and the second cage is evenly provided with a plurality of retaining holes in a circumferential direction, and both ends of the plurality of second rollers are respectively rotationally connected in the plurality of retaining holes.

[0024] Optionally, the second roller and the second screw have a pitch diameter drawn according to a corresponding theoretical pitch diameter value, the second roller and the second screw have a flank angle drawn according to a 45-degree symmetry, the second roller and the second screw have a same thread angle, and the second nut has a flank angle drawn according to a modified angle.

[0025] A second object of the present application is to provide a thread flank angle optimization design system for a planetary roller screw pair based on the above-mentioned method, the design system comprising:

[0026] A digital model establishing module is configured to draw a standard thread flank three-dimensional digital model of the screw, the roller and the nut according to thread parameters of the planetary roller screw pair.

[0027] An engagement analysis module is configured to perform engagement analysis on a part of thread segments of the screw or the nut and the roller in a simulation module of the three-dimensional software.

[0028] The simulation module comprises an interference checking function command, and a determination parameter of the interference checking function command is set to be less than 0.000001 mm 3 .

[0029] An adjusting module is configured to adjust a flank angle value of the first screw based on engagement of a part of thread segments of the first screw and the first roller in a standard planetary roller screw pair structure, so that the first screw and the first roller realize optimization of mutual engagement positions under a non-interference engagement premise.

[0030] The adjusting module is also configured to adjust a flank angle value of the second nut based on engagement of a part of thread segments of the second nut and the second roller in a reverse planetary roller screw pair structure, so that the second nut and the second roller realize optimization of mutual engagement positions under a non-interference engagement premise.

[0031] Compared with the prior art, the present application has the following beneficial effects:

[0032] The thread flank angle optimization design method for the planetary roller screw pair comprises the following steps: drawing a standard thread flank three-dimensional digital model of the screw, the roller and the nut according to thread parameters of the planetary roller screw pair through three-dimensional software; and performing engagement analysis on a part of thread segments of the screw or the nut and the roller in a simulation module of the three-dimensional software, wherein the simulation module comprises an interference checking function command, and a determination parameter of the interference checking function command is set to be less than 0.000001 mm 3; based on the meshing condition of the first screw and the first roller in the standard planetary roller screw pair structure, the number of thread angles of the first screw is adjusted to make the first screw and the first roller realize the optimization of the mutual meshing position without interference; or based on the meshing condition of the second nut and the second roller in the reverse planetary roller screw pair structure, the number of thread angles of the second nut is adjusted to make the second nut realize the optimization of the mutual meshing position without interference. The thread angle optimization design method of the planetary roller screw pair not only reduces thread wear, but also improves the carrying capacity, transmission efficiency, service life and safety factor of the planetary roller screw pair, and the specific analysis is as follows:

[0033] 1. Improve the carrying capacity of the planetary roller screw pair. In the standard planetary roller screw pair structure or the reverse planetary roller screw pair structure, if the thread angle of the part with inconsistent thread angle (the first screw in the standard structure and the second nut in the reverse structure) is set to 45° symmetrical thread angle, the meshing point will be very close to the tooth top of one of the mutually meshing parts, and the tooth top is the weakest part, which will cause the stress of the tooth bottom to increase sharply under load, increasing the risk of fatigue fracture.

[0034] The thread angle optimization design method in the application adjusts the thread angle of the part with inconsistent thread angle to make the meshing point fall in the middle position between the pitch circles of the two meshing parts, so that the high carrying capacity of the planetary roller screw pair can be effectively utilized.

[0035] 2. Improve the transmission efficiency. In the standard planetary roller screw pair structure or the reverse planetary roller screw pair structure, after the thread angle of the part with inconsistent thread angle (the first screw in the standard structure and the second nut in the reverse structure) is optimized, the thread meshing point moves to a better position, the meshing circle diameter changes, the ratio of the meshing circle diameters between the screw, roller and nut is closer to the theoretical required value, and the proportion of thread sliding friction during thread transmission is reduced, thereby improving the transmission efficiency.

[0036] 3. Reduce thread wear. In the standard planetary roller screw pair structure or the reverse planetary roller screw pair structure, after the thread angle of the part with inconsistent thread angle (the first screw in the standard structure and the second nut in the reverse structure) is optimized, the thread meshing point moves to a better position, the meshing circle diameter changes, the ratio of the meshing circle diameters between the screw, roller and nut is closer to the theoretical required value, and the proportion of sliding friction is reduced, thereby reducing the degree of thread wear.

[0037] 4. The service life and safety factor are improved, whether in the standard planetary roller screw pair structure or the reverse planetary roller screw pair structure, after the tooth type angle is optimized, the stress of the thread tooth bottom is reduced under the same load, the degree of thread wear is reduced, and the service life and safety factor are directly improved. BRIEF DESCRIPTION OF DRAWINGS

[0038] Figure 1 A flowchart of the thread tooth type angle optimization design method of the planetary roller screw pair in the embodiment of the application is shown in the figure.

[0039] Figure 2 A schematic diagram of the engagement structure of the roller and the screw or the nut in the embodiment of the application is shown in the figure.

[0040] Figure 3 A longitudinal sectional view of the standard planetary roller screw pair structure in the embodiment of the application is shown in the figure.

[0041] Figure 4 A transverse sectional view of the standard planetary roller screw pair structure in the embodiment of the application is shown in the figure.

[0042] Figure 5 A three-dimensional schematic diagram of the engagement of the first roller and the first screw before adjustment and optimization of the standard planetary roller screw pair structure in the embodiment of the application is shown in the figure.

[0043] Figure 6 A three-dimensional schematic diagram of the engagement of the roller and the screw after adjustment of the standard planetary roller screw pair in the embodiment of the application is shown in the figure.

[0044] Figure 7 A planar structural schematic diagram of the engagement point and the pitch circle distance before and after adjustment of the standard planetary roller screw pair in the embodiment of the application is shown in the figure.

[0045] Figure 8 A sectional view of the planetary roller screw pair in the embodiment of the application is shown in the figure.

[0046] Figure 9 A three-dimensional schematic diagram of the engagement of the roller and the nut before adjustment of the reverse planetary roller screw pair in the embodiment of the application is shown in the figure.

[0047] Figure 10 A three-dimensional schematic diagram of the engagement of the roller and the nut after adjustment of the reverse planetary roller screw pair in the embodiment of the application is shown in the figure.

[0048] Figure 11 A planar structural schematic diagram of the engagement point and the pitch circle distance before and after adjustment of the reverse planetary roller screw pair in the embodiment of the application is shown in the figure.

[0049] Figure 12 A schematic diagram of the thread tooth type angle optimization design system structure of the planetary roller screw pair in the embodiment of the application is shown in the figure.

[0050] BRIEF DESCRIPTION OF DRAWINGS

[0051] 10-standard planetary roller screw pair structure

[0052] 11-first nut; 12-first right gear ring; 13-first retainer; 14-first screw; 15-first left gear ring; 16-first roller; 17-locking screw; 18-pin

[0053] 20-reverse planetary roller screw pair structure

[0054] 21-second nut; 211-nut thread; 22-second screw; 221-screw thread; 222-screw gear; 23-second roller; 231-roller thread; 232-roller gear; 24-second retainer DETAILED DESCRIPTION

[0055] The technical solutions of the present application will be described clearly and completely below in combination with the drawings. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0056] In the description of the present application, it should be noted that the terms "first", "second", etc. are only for the purpose of description, and cannot be understood as indicating or implying relative importance.

[0057] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "mounting", "connecting", "connection" should be understood broadly, for example, it can be fixed connection, or detachable connection, or integrally connected; it can be mechanical connection, or electrical connection; it can be directly connected, or indirectly connected through intermediate medium, or the internal communication of two elements, it can be wireless connection, or wired connection. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0058] In addition, the technical features involved in the different embodiments of the present application described below can be combined with each other as long as there is no conflict between them.

[0059] At present, the three core threaded parts of the planetary roller screw pair: screw, roller, nut, their tooth profile angle is generally designed as symmetrical tooth profile angle with left and right tooth side angle of 45°, such as Figure 2As shown in the figure. However, due to the inconsistent thread angles of the three, the design of the three 45° thread angle cannot guarantee that the roller thread is close to the pitch circle when meshing with the screw or nut, but is very close to the tooth top, which has many disadvantages.

[0060] To solve the technical problem of poor thread meshing point position of the roller due to inconsistent thread angles in the existing standard and reverse planetary roller screw pair, please refer to Figure 1 As shown in the figure. The embodiment of the present application provides a thread profile angle optimization design method for a planetary roller screw pair, which comprises the following steps:

[0061] S1: According to the thread parameters of the planetary roller screw pair, the standard thread profile three-dimensional model of the screw, roller and nut is drawn through three-dimensional software;

[0062] The planetary roller screw pair includes a standard planetary roller screw pair structure and a reverse planetary roller screw pair structure.

[0063] S2: The meshing analysis of the screw or nut and part of the thread segment of the roller is carried out in the simulation module of the three-dimensional software.

[0064] The simulation module includes an interference check function command, and the determination parameter of the interference check function command is set to be less than 0.000001mm 3 ;

[0065] S3: Based on the meshing condition of the first screw 14 and the first roller 16 in the standard planetary roller screw pair structure 10, the thread angle value of the first screw 14 is adjusted to optimize the mutual meshing position of the first screw 14 and the first roller 16 without interference.

[0066] Based on the meshing condition of the second nut 21 and the second roller 23 in the reverse planetary roller screw pair structure 20, the thread angle value of the second nut 21 is adjusted to optimize the mutual meshing position of the second nut 21 and the second roller 23 without interference.

[0067] In the prior art, whether in the standard planetary roller screw pair structure 10 or in the reverse planetary roller screw pair structure 20, if the thread angle of the part (the first screw 14 in the standard structure and the second nut 21 in the reverse structure) is inconsistent, the thread is set to a symmetrical thread angle of 45°, which will cause the meshing point to be very close to the tooth top of one of the mutually meshing parts. As the tooth top is the weakest part, the stress of the tooth bottom will increase sharply under load, increasing the risk of fatigue fracture.

[0068] The thread tooth form angle optimization design method in the application can make the meshing point fall in the middle position between the pitch circles of the two meshing parts by adjusting the thread tooth form angle of the part with inconsistent thread lead angle, so that the high bearing characteristics of the planetary roller screw pair itself can be more effectively exerted.

[0069] Secondly, whether in the standard planetary roller screw pair structure 10 or the reverse planetary roller screw pair structure 20, after the thread tooth form angle of the part with inconsistent thread lead angle (the first screw 14 in the standard structure and the second nut 21 in the reverse structure) is optimized, the thread meshing point moves to a better position, the meshing circle diameter is changed, the meshing circle diameter ratio relationship between the screw, the roller and the nut is closer to the theoretical required value, and then the proportion of thread sliding friction during thread transmission is reduced, so that the transmission efficiency is improved.

[0070] Thirdly, whether in the standard planetary roller screw pair structure or the reverse planetary roller screw pair structure, after the thread tooth form angle of the part with inconsistent thread lead angle (the first screw in the standard structure and the second nut 21 in the reverse structure) is optimized, the thread meshing point moves to a better position, the meshing circle diameter is changed, the meshing circle diameter ratio relationship between the screw, the roller and the nut is closer to the theoretical required value, the sliding friction proportion is reduced, and the thread wear degree is reduced.

[0071] Fourthly, the service life and safety factor are improved, whether in the standard planetary roller screw pair structure 10 or the reverse planetary roller screw pair structure 20, after the thread tooth form angle is optimized, under the same load condition, the stress on the thread tooth bottom is reduced, and the thread wear degree is reduced, which directly improves the service life and safety factor.

[0072] Further, in step S1, the three-dimensional software is any one of Solidworkd software, Creo software and CATIA software.

[0073] It can be understood that, in the three-dimensional drawing software, as long as it has a three-dimensional simulation function, the thread tooth form angle optimization design of the planetary roller screw pair can be realized. In some other simulation software, when it has a three-dimensional simulation function, secondary development can also realize the above function.

[0074] Further, please refer to Figure 3 、 Figure 4 As shown in the drawings, the standard planetary roller screw pair structure 10 includes a first nut 11, a first right gear ring 12, a first retainer 13, a first screw 14, a first left gear ring 15, n first rollers 16, 2 locking screws 17 and 8 pin bolts 18, wherein:

[0075] The first screw rod 14 is axially horizontally placed; the first retainer 13 is sleeved on the outer wall of the first screw rod 14; the n first rollers 16 are uniformly embedded in the first retainer 13 in a circumferential direction, the n first rollers 16 are all arranged in parallel with the axis of the first screw rod 14, and the n first rollers 16 are all threadedly matched with the first screw rod 14; the first nut 11 is sleeved on the outer wall of the first retainer 13; the first left gear ring 15 and the first right gear ring 12 are both arranged on the inner wall of the first nut 11 and are sleeved on the outer wall of the n first rollers 16;

[0076] The first left gear ring 15 is correspondingly arranged at the axially left end position of the first roller 16; the first right gear ring 12 is correspondingly arranged at the axially right end position of the first roller 16;

[0077] The first left gear ring 15 and the first right gear ring 12 are fixedly connected with the first nut 11 through one locking screw 17 and four pin nails 18 respectively; n is a positive integer.

[0078] Further, in the embodiment of the application, the pitch diameter of the first roller 16 and the first nut 11 is drawn according to a theoretical pitch diameter value, the tooth profile angle of the first roller 16 and the first nut 11 is symmetrically drawn at 45 degrees, the thread angle of the first roller 16 and the first nut 11 is the same, and the tooth profile angle of the first screw rod 14 is symmetrically drawn at a corrected angle (not 45 degrees).

[0079] Embodiment one:

[0080] When the standard planetary roller screw pair structure 10 is selected as the planetary roller screw pair, as the preferred embodiment of the present application, the specific model of the standard planetary roller screw pair structure 10 is 1806, and the parameters of the screw pair with the model 1806 are as follows:

[0081] The thread pitch diameter of the first screw rod 14 is 18.9 mm;

[0082] The thread pitch diameter of the first roller 16 is 6.3 mm;

[0083] The thread pitch diameter of the first nut 11 is 31.5 mm;

[0084] The thread angle of the first nut 11 / the first roller 16 is 3.49°;

[0085] The thread angle of the first screw rod 14 is 5.77°;

[0086] The thread rotation direction is all right-handed;

[0087] The thread head number is 5 for the first screw rod 14 and the first nut 11, and the first roller 16 is single-threaded;

[0088] The lead is 6 mm;

[0089] The pitch is 1.2 mm.

[0090] Please refer to the specific structure as shown in Figure 3 、 Figure 4 , the standard type planetary roller screw pair structure 10 mainly includes a first nut 11, a first right gear ring 12, a first retainer 13, a first screw 14, a first left gear ring 15, n first rollers 16, 2 locking screws 17 and 8 pins 18, wherein the first screw 14 is placed axially horizontally and threaded on the first nut 11, and two first retainers 13 are sleeved on the outer wall of the first screw 14 and located on the inside of the first nut 11 on both sides; the first retainer 13 is a limiting mechanism for the first roller 16, and in this embodiment, the first retainer 13 is provided in the form of a ring frame structure; the two first retainers 13 are placed axially horizontally and coaxially on both sides of the first roller 16, and the ring frame structure is uniformly provided with n circular through holes in the circumferential direction, each first roller 16 is embedded in a circular through hole, and the n first rollers 16 are uniformly embedded in the first retainer 13 in the circumferential direction, the n rollers 16 are arranged in parallel with the axis of the first screw 14, and the n first rollers 16 are in threaded cooperation with the first screw 14; the first nut 11 is sleeved on the outer wall of the first retainer 13; the first left gear ring 15 and the first right gear ring 12 are arranged on the inner wall of the first nut 11 and sleeved on the outer wall of the n first rollers 16, the first left gear ring 15 is arranged at the axial left end of the first roller 16, and the first right gear ring 12 is arranged at the axial right end of the first roller 16; the first left gear ring 15 and the first right gear ring 12 are fixedly connected with the first nut 11 by one locking screw 17 and four pins 18 respectively; n is a positive integer, and 9≤n≤12.

[0091] The circumferential outer wall of the first screw 14 is provided with threads; the inner walls of the first right gear ring 12 and the first left gear ring 15 are provided with internal teeth; the axial middle outer wall and the axial both end outer wall of the first roller 16 are provided with external teeth; the threads in the middle of the first roller 16 correspond to and cooperate with the threads of the first screw 14; the external teeth at both axial ends of the first roller 16 are respectively meshed and cooperated with the internal teeth of the first right gear ring 12 and the first left gear ring 15. When the first screw 14 rotates along the axial direction, the n first rollers 16 are realized to make planetary rotation around the first screw 14 and axial movement relative to the first screw 14 through the threaded cooperation with the first screw 14, and the first retainer 13 is realized to rotate around the first screw 14 and axially move relative to the first screw 14.

[0092] The first right gear ring 12 and the first left gear ring 15 have the same number of teeth and the same tooth arrangement; the inner teeth of the first right gear ring 12 and the outer teeth of the axially corresponding end of the first roller 16 have the same rotation direction; the inner teeth of the first left gear ring 15 and the outer teeth of the axially corresponding end of the first roller 16 have the same rotation direction, so that the first nut 11 rotates synchronously and moves translationally relative to the first screw 14 under the driving of the first roller 16, and the first nut 11 does not move axially relative to the first roller 16, and the first nut 11 rotates one revolution around the first screw 14, and the first nut 11 moves axially relative to the first screw 14 by one pitch distance.

[0093] The first right gear ring 12 and the first left gear ring 15 are fixedly connected with the first nut 11, and the tight locking screw 17 and the pin 18 are used to limit the relative rotation of the gear ring and the first nut 11, and the position of the gear ring relative to the first nut 11 is adjusted during installation to fine-tune the phase angle relationship between the two gear rings, so that the teeth of the left and right gear rings have the same phase angle.

[0094] The following describes the design steps of the standard planetary roller screw pair structure 10 by using the thread profile angle optimization design method of the planetary roller screw pair as follows:

[0095] Step S1: according to the thread parameters of the standard planetary roller screw pair structure 10, the standard thread profile 3D model of the first screw 14, the first roller 16 and the first nut 11 is drawn by using the Solidworks software.

[0096] The pitch diameter of the first roller 16 and the first nut 11 is drawn according to the theoretical pitch diameter value, the profile angle is drawn according to the symmetrical flank angle of 45°, the thread angle of the first roller 16 and the first nut 11 is the same, the first roller 16 and the first nut 11 can mesh at the pitch circle between them without interference; the profile angle of the first screw 14 is also drawn according to the symmetrical flank angle of 45°, and then optimized according to the meshing condition.

[0097] Step S2: select part of the thread segments of the first screw 14 and the first roller 16 for meshing analysis, and use the Simulation simulation module in the Solidworks software and the function command of “interference check” to adjust the thread pitch diameter value of the first screw 14 so that the first roller 16 and the first screw 14 can mesh without interference.

[0098] During the interference check, when the determination parameter of “interference check” is set to 0.000001mm 3 , and less than this value is considered as just contact.

[0099] Step S3: by adjusting, when the pitch diameter value of the first screw 14 is 18.8455mm, the meshing is just right.

[0100] For example Figure 5As shown, before adjustment, in the above steps S1-S3, it can be determined by the poor engagement result that the left tooth flank angle of the first screw 14 needs to be increased and the right tooth flank angle of the first screw 14 needs to be increased so as to make the engagement point continuously close to the middle position of the pitch circles of the first roller 16 and the first screw 14, at this time, the engagement point positions of the first roller 16 and the first screw 14 at this time are simulated as points A and B. The distance between the points A and B and the pitch circle of the first roller 16 is 0.012 mm, and the distance between the points A and B and the pitch circle of the first screw 14 is 0.045 mm. It is obvious that the engagement point is very close to the tooth top position of the first screw 14 at this time.

[0101] As shown in Figure 6 , 7 As shown, after adjustment, the pitch diameter value of the first screw 14 can remain unchanged at 18.845 mm, the left and right tooth flank angles of the first screw 14 are adjusted to 45.3° and 45.3° respectively, and the engagement point positions at this time are points A' and B'. The distance between the points A' and B' and the pitch circle of the first roller 16 is 0.0282 mm, and the distance between the points A' and B' and the pitch circle of the first screw 14 is also 0.0282 mm. At this time, the engagement point is just located at the middle position of the pitch circles of the first roller 16 and the first screw 14.

[0102] Further, as shown in Figure 8 , the reverse type planetary roller screw pair structure 20 comprises a second nut 21, a second screw 22 moving linearly relative to the second nut 21, and a plurality of second rollers 23 arranged between the second nut 21 and the second screw 22.

[0103] The outer wall of the second screw 22 is provided with a screw thread 221, and a screw gear 222 is arranged on both sides of the screw thread 221; the middle part of the second roller 23 is provided with a roller thread 231 matched with the screw thread 221, and both ends are provided with a roller gear 232 matched with the screw gear 222; the inner wall of the second nut 21 is provided with a nut thread 211 matched with the roller thread 231, and the screw thread 221 and the nut thread 211 are both multi-start threads.

[0104] Two second retainer cages 24 are arranged on the second screw 22, the second retainer cage 24 is uniformly provided with a plurality of retaining holes in the circumferential direction, and both ends of the plurality of second rollers 23 are respectively connected in the plurality of retaining holes.

[0105] Further, as shown in Figure 8 , the pitch diameters of the second roller 23 and the second screw 22 are drawn according to the corresponding theoretical pitch diameter values, the tooth profile angles of the second roller 23 and the second screw 22 are both drawn symmetrically at 45 degrees, the thread angles of the second roller 23 and the second screw 22 are the same, and the tooth profile angle of the second nut 21 is drawn symmetrically at the corrected angle (not 45 degrees).

[0106] Example Two:

[0107] When the planetary roller screw pair is selected as the reverse type planetary roller screw pair structure 20, as the preferred embodiment of the present embodiment, the specific model of the reverse type planetary roller screw pair structure 20 is 1203, and the parameters of the screw pair with the model number 1203 are as follows:

[0108] The thread pitch diameter of the second screw 22 is 12 mm;

[0109] The thread pitch diameter of the second roller 23 is 6 mm;

[0110] The thread pitch diameter of the second nut 21 is 24 mm;

[0111] The thread angle of the second screw 22 / second roller 23 is 4.55°;

[0112] The thread angle of the second nut 21 is 2.28°;

[0113] The thread rotation direction: the second screw 22 and the second nut 21 are right-handed threads, and the second roller 23 is a left-handed thread;

[0114] The number of threads: the second screw 22 and the second nut 21 are both 2 threads, and the second roller 23 is a single-thread screw;

[0115] The lead is 3 mm

[0116] The pitch is 1.5 mm.

[0117] Please refer to the specific structure as Figure 8As shown, the reverse planetary roller screw pair structure 20 includes a second nut 21, a second screw 22 moving linearly relative to the second nut 21, and a plurality of second rollers 23 arranged between the second nut 21 and the second screw 22 to transmit torque to the second screw 22 to make the second screw 22 move linearly. The inner wall of the second nut 21 is provided with nut threads 211, which are multi-start threads, used to cooperate with the second rollers 23 to transmit torque. The second rollers 23 are arranged circumferentially along the second screw 22, and the second retainer 24 is sleeved on the second screw 22 and located at both ends of the second rollers 23. The outer wall of the second screw 22 is provided with screw threads 221, which are multi-start threads, used to cooperate with the threads of the second rollers 23 to receive torque transmitted by the rollers. The outer wall of the second screw 22 is provided with screw gears 222 on both sides of the screw threads 221, used to cooperate with the roller gears 232 on the second rollers 23 to ensure that the second rollers 23 rotate around them. The middle part of the second roller 23 is provided with roller threads 231, which are single-start threads, cooperating with the threads on the second nut 21 and the second screw 22. The two sides of the roller threads 231 are provided with roller gears 232, used to cooperate with the screw gears 222. The roller threads 231 and the roller gears 232 also have a clearance structure therebetween. The two ends of the second roller 23 are mating ends, used to cooperate with the second retainer 24. The second retainer 24 is sleeved on the second screw 22.

[0118] The thread profile angle optimization design method of the reverse planetary roller screw pair structure 20 is designed as follows:

[0119] Step S1: According to the thread parameters of the reverse planetary roller screw pair structure 20, the standard thread profile 3D model of the second screw 22, the second roller 23, and the second nut 21 is drawn by using the Solidworkd software.

[0120] The middle diameter of the second roller 23 and the second screw 22 is drawn according to the theoretical middle diameter value, and the profile angle is drawn according to the 45° symmetrical flank angle. The thread angles of the second roller 23 and the second screw 22 are the same, and the second roller 23 and the second screw 22 can mesh at the pitch circle therebetween without interference. The profile angle of the second nut 21 is also drawn according to the 45° symmetrical flank angle, and then optimized according to the meshing condition.

[0121] Step S2: Select partial thread segments of the second nut 21 and the second roller 23 for meshing analysis. Through the Simulatio n simulation module in the Solidworks software and using the “interference check” function command, continuously adjust the thread diameter value of the second nut 21 so that the second roller 23 and the second nut 21 can just achieve non-interference meshing.

[0122] During the interference check process, when the judgment parameter of "interference check" is set to 0.000001mm 3 , when it is less than this value, it is considered as just contact.

[0123] Step S3: Through adjustment, when the median diameter of the second nut 21 is 24.052 mm, the meshing is just achieved.

[0124] like Figure 9 As shown, before adjustment, in steps S1-S3, the poor meshing results indicate that the left and right flank angles of the second nut 21 need to be increased to allow the meshing point to continuously approach the midpoint between the pitch circles of the second roller 23 and the second nut 21. At this point, the meshing points of the second roller 23 and the second nut 21 are simulated at points C and D. Points C and D are 0.0148 mm from the pitch circle of the second roller 23 and 0.068 mm from the pitch circle of the second nut 21, respectively. Clearly, the meshing points are very close to the crests of the second nut 21.

[0125] like Figure 10 、 11 As shown, after adjustment, the pitch diameter of the second nut 21 needs to be adjusted to 24.0497 mm. When the left and right flank angles of the second nut 21 are adjusted to 45.4° and 45.4°, respectively, the meshing points are now located at points C' and D'. The distance between points C' and D' and the pitch circle of the second roller 23 is 0.0262 mm, and the distance between points C' and D' and the pitch circle of the second nut 21 is also 0.0262 mm. At this point, the meshing point is exactly halfway between the pitch circles of the second roller 23 and the second nut 21.

[0126] See also Figure 12 As shown, another embodiment of the present invention further provides a thread profile angle optimization design system for a planetary roller screw pair, the design system comprising:

[0127] The digital model building module 100 is used to draw a three-dimensional digital model of the standard thread profile of the screw, roller, and nut based on the thread parameters of the planetary roller screw pair;

[0128] An engagement analysis module 200 is used to perform engagement analysis on a partial thread segment of the lead screw and the roller in a simulation module of a three-dimensional software;

[0129] The simulation module includes an interference checking function command, and a determination parameter of the interference checking function command is set to be less than 0.000001 mm 3 ;

[0130] The adjusting module 300 is configured to adjust the profile angle value of the first screw 14 based on the meshing condition of the partial thread segments of the first screw 14 and the first roller 16 in the standard planetary roller screw pair structure 10, so that the first screw 14 and the first roller 16 realize the optimization of the mutual meshing position under the premise of non-interference meshing.

[0131] The adjusting module 300 is configured to adjust the profile angle value of the first screw 14 based on the meshing condition of the partial thread segments of the first screw 14 and the first roller 16 in the standard planetary roller screw pair structure 10, so that the first screw 14 and the first roller 16 realize the optimization of the mutual meshing position under the premise of non-interference meshing.

[0132] The specific limitations of the thread profile angle optimization design system of the planetary roller screw pair can refer to the limitations of the thread profile angle optimization design method of the planetary roller screw pair in the above, and will not be repeated here. Each module in the thread profile angle optimization design system of the planetary roller screw pair can be realized by software, hardware and combinations thereof, in whole or in part. The above modules can be embedded in or independent of the processor in the computer device in hardware form, or can be stored in the memory in the computer device in software form, so as to be called and executed by the processor to perform the operations corresponding to each module.

[0133] Although the present disclosure is disclosed as above, the protection scope of the present disclosure is not limited to this. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present disclosure, and these changes and modifications will fall within the protection scope of the present disclosure.

Claims

1. A method for optimizing the thread profile angle of a planetary roller screw pair, characterized in that: The design method comprises the steps of: S1: Based on the thread parameters of the planetary roller screw pair, a 3D digital model of the standard thread profile of the screw, roller, and nut is drawn using 3D software; Wherein, the planetary roller screw pair includes a standard planetary roller screw pair structure and a reverse planetary roller screw pair structure; S2: performing meshing analysis on a partial thread segment of the lead screw or the nut and the roller in a simulation module of the three-dimensional software; The simulation module includes an interference check function command, and the judgment parameter of the interference check function command is set to be less than 0.000001 mm³; S3: Based on the meshing of partial thread segments of the first screw and the first roller in the standard planetary roller screw pair structure, adjust the tooth profile angle value of the first screw so that the first screw and the first roller can optimize the mutual meshing position without interfering with each other; the standard planetary roller screw pair structure includes a first nut, a first right ring gear, a first retaining frame, the first screw, a first left ring gear, n first rollers, two locking screws and eight pins; the mean diameters of the first roller and the first nut are drawn according to the theoretical mean diameter value, the tooth profile angles of the first roller and the first nut are drawn symmetrically at 45 degrees, and the thread lead angles of the first roller and the first nut are the same; the tooth profile angles of the first screw are drawn symmetrically according to the corrected angles; or Based on the meshing condition of the second nut and the partial threaded section of the second roller in the inverted planetary roller screw pair structure, the tooth profile angle value of the second nut is adjusted to optimize the mutual meshing position of the second nut without interfering with the meshing; The mean diameters of the second roller and the second screw are drawn according to the corresponding theoretical mean diameter values, the tooth angles of the second roller and the second screw are drawn symmetrically at 45 degrees, the thread lead angles of the second roller and the second screw are the same, and the tooth angles of the second nut are drawn symmetrically according to the corrected angles.

2. The method for optimizing the thread profile angle of a planetary roller screw pair according to claim 1, wherein: In step S1, the three-dimensional software is any one of Solidworkd software, Creo software and CATIA software.

3. The method for optimizing the thread profile angle of a planetary roller screw pair according to claim 1, wherein: The first screw is axially placed horizontally; the first retaining frame is sleeved on the outer wall of the first screw; n first rollers are evenly embedded in the first retaining frame along the circumferential direction, the n first rollers are all arranged parallel to the axis of the first screw, and the n first rollers are all engaged with the first screw thread; the first nut is sleeved on the outer wall of the first retaining frame; the first left gear ring and the first right gear ring are both arranged on the inner wall of the first nut and sleeved on the outer walls of the n first rollers; The first left gear ring is correspondingly arranged at the axial left end position of the first roller; the first right gear ring is correspondingly arranged at the axial right end position of the first roller; The first left gear ring and the first right gear ring are respectively fixedly connected to the first nut via one locking screw and four pins; n is a positive integer.

4. The method for optimizing the thread profile angle of a planetary roller screw pair according to claim 1, wherein: The reverse planetary roller screw pair structure includes the second nut, a second screw that moves linearly relative to the second nut, and a plurality of second rollers arranged between the second nut and the second screw; The outer wall of the second screw is provided with a screw thread, and screw gears are provided on both sides of the screw thread; the middle part of the second roller is provided with a single-start thread that cooperates with the screw thread, and both ends of the second roller are provided with roller gears that cooperate with the screw gear; the inner wall of the second nut is provided with a nut thread that cooperates with the single-start thread, and the screw thread and the nut thread are both multi-start threads; A second retaining frame is provided on the second lead screw. The second retaining frame is evenly provided with a plurality of retaining holes along the circumferential direction. Both end portions of the plurality of second rollers are rotatably connected to the plurality of retaining holes respectively.

5. A planetary roller screw thread profile angle optimization design system based on the method according to any one of claims 1 to 4, characterized in that: The design system includes: The digital model building module is used to draw the standard thread profile 3D digital model of the screw, roller and nut based on the thread parameters of the planetary roller screw pair; Wherein, the planetary roller screw pair includes a standard planetary roller screw pair structure and a reverse planetary roller screw pair structure; an engagement analysis module, configured to perform engagement analysis on a partial thread segment of the lead screw or the nut and the roller in a simulation module of a three-dimensional software; The simulation module includes an interference check function command, and the judgment parameter of the interference check function command is set to be less than 0.000001 mm³; an adjustment module for adjusting a tooth angle value of the first lead screw based on meshing conditions of partial thread segments of the first lead screw and the first roller in a standard planetary roller screw pair structure, so as to optimize the mutual meshing position of the first lead screw and the first roller without interfering with the meshing; The standard planetary roller screw pair structure includes a first nut, a first right ring gear, a first retaining frame, the first screw, a first left ring gear, n first rollers, two locking screws and eight pins; the pitch diameters of the first rollers and the first nut are drawn according to the theoretical pitch diameter values, the thread angles of the first rollers and the first nut are drawn symmetrically at 45 degrees, and the thread lead angles of the first rollers and the first nut are the same; the thread angles of the first screw are drawn symmetrically according to the corrected angles; or Used to adjust the tooth profile angle value of the second nut based on the meshing condition of the partial thread segments of the second nut and the second roller in the reverse planetary roller screw pair structure, so that the second nut and the second roller can achieve the optimized mutual meshing position without interfering with the meshing; The mean diameters of the second roller and the second screw are drawn according to the corresponding theoretical mean diameter values, the tooth angles of the second roller and the second screw are drawn symmetrically at 45 degrees, the thread lead angles of the second roller and the second screw are the same, and the tooth angles of the second nut are drawn symmetrically according to the corrected angles.

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