Optimization design method for thread angle of planetary roller screw pair

Abstract

The invention relates to an optimal design method for a thread form angle of a planetary roller lead screw pair, and relates to the technical field of planetary roller lead screws, the method comprises the following steps: drawing standard thread form three-dimensional mathematical models of a lead screw, a roller and a nut in three-dimensional software according to thread parameters of the planetary roller lead screw pair; performing meshing analysis on the screw rod or the nut and partial thread section of the roller in a simulation module of the three-dimensional software; the thread angle value of the first lead screw or the second nut is adjusted based on the meshing condition of partial thread sections of the first lead screw and the first roller in the standard structure or the meshing condition of partial thread sections of the second nut and the second roller in the reverse structure. Therefore, on the premise that the first pin roller and the first lead screw or the second nut and the second pin roller do not interfere with meshing, the mutual meshing position is optimized. According to the design method, the thread angle value of the lead screw or the nut is optimized, the problem of poor thread meshing is solved, the bearing capacity and the transmission efficiency are improved, thread abrasion is reduced, and the service life is prolonged.

Description

Technical Field

[0001] The invention relates to the technical field of planetary roller screw design, and in particular to a method for optimizing the design of a thread profile angle of a planetary roller screw pair. Background Art

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

[0003] The Chinese invention patent with the publication number CN113987717B discloses a planetary roller screw tolerance optimization design method. The design method is based on the structure and transmission principle of the planetary roller screw, and determines the main error factors that affect the transmission accuracy of the planetary roller screw during the transmission process; based on the main error factors, a mathematical model with stroke accuracy and axial clearance as the objective function is constructed, and the constraints of the optimization target are determined; a sensitivity analysis is performed on the influence of the part design parameters on the stroke accuracy and axial clearance of the planetary roller screw, and the processing difficulty of each part is determined by using the hierarchical analysis method based on triangular fuzzy numbers; the weight coefficient is constructed by using the geometric mean, and the weight expression of each design parameter is established to allocate the tolerance of the planetary roller screw; the fmincon algorithm is used to optimize and solve the fitness function of the axial clearance, and the result is output. The planetary roller screw tolerance optimization design method can design a reasonable part size tolerance value under the premise of meeting the corresponding technical indicators.

[0004] However, the above tolerance optimization design method needs to establish the thread surface equations of the screw, roller and nut, and solve the cumbersome and complicated process through analytical calculation. The theoretical calculation process is quite complicated, which is not conducive to the actual production operation adjustment. Moreover, it only involves the tolerance design method of the thread 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 issues are still at the basic stage, with unclear goals and ignoring the impact of the meshing deviation between the screw, roller and nut on the life of the planetary roller screw pair's load-bearing capacity, making the optimization results inaccurate.

[0006] At present, the tooth angles of the three core threaded parts of the planetary roller screw pair: screw, roller, and nut are generally designed to be symmetrical with the left and right tooth angles being 45°. Due to the inconsistency of the three thread lead angles, this design of 45° tooth angles does not ensure that the roller thread is kept close to the pitch circle when meshing with the screw or nut, but very close to the tooth top, which increases the risk of fatigue fracture, increases thread wear, prevents the improvement of transmission efficiency, and reduces service life and safety factor. Summary of the invention

[0007] In view of this, the purpose of the present invention is to overcome the technical problem that the tolerance optimization design method of the planetary roller screw in the background technology ignores the influence of the meshing position deviation between the screw, roller and nut on the load-bearing capacity, thread wear, transmission efficiency, service life, etc., thereby providing a thread profile angle optimization design method for a planetary roller screw pair.

[0008] In order to solve the above problems, the first object of the present invention is to provide a method for optimizing the design of the thread profile angle of a planetary roller screw pair, the design method comprising the steps of:

[0009] S1: Based on the thread parameters of the planetary roller screw pair, the 3D digital model of the standard thread profile of the screw, roller and nut is drawn using 3D software;

[0010] Wherein, the planetary roller screw pair includes a standard planetary roller screw pair structure and a reverse planetary roller screw pair structure;

[0011] 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;

[0012] The simulation module includes an interference check function command, and the judgment parameter of the interference check function command is set to less than 0.000001mm. 3 ;

[0013] S3: Based on the meshing condition of the partial threaded sections of the first screw and the first roller in the standard new roller screw pair structure, adjusting the tooth angle value of the first screw so that the first screw and the first roller can achieve the optimization of the mutual meshing position without interfering with the meshing; or

[0014] Based on the meshing condition of the partial threaded sections of the second nut and the second roller in the reverse planetary roller screw pair structure, the tooth angle value of the second nut is adjusted so that the mutual meshing position of the second nut and the second roller is optimized without interfering with the meshing.

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

[0016] Optionally, the standard planetary roller screw pair structure includes a first nut, a first right gear ring, a first retaining frame, the first screw, a first left gear ring, n first rollers, two locking screws and eight pins;

[0017] The first screw is placed axially and horizontally; the first holder is sleeved on the outer wall of the first screw; n first rollers are uniformly embedded in the first holder along the circumferential direction, the n first rollers are arranged parallel to the axis of the first screw, and the n first rollers are threadedly matched with the first screw; the first nut is sleeved on the outer wall of the first holder; 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;

[0018] 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;

[0019] 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.

[0020] Optionally, the mean diameters of the first roller and the first nut are drawn according to the theoretical mean diameter values, the tooth angles of the first roller and the first nut are drawn symmetrically at 45 degrees, the thread lead angles of the first roller and the first nut are the same; the tooth angle of the first screw is drawn symmetrically according to the corrected angle.

[0021] Optionally, 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 disposed between the second nut and the second screw;

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

[0023] The second screw is provided with a second retaining frame, and the second retaining frame is evenly provided with a plurality of retaining holes along the circumferential direction, and both end portions of the plurality of second rollers are rotatably connected to the plurality of retaining holes respectively.

[0024] Optionally, 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 angle of the second nut is drawn symmetrically according to the corrected angle.

[0025] The second object of the present invention is to provide a thread profile angle optimization design system for a planetary roller screw pair based on the above method, the design system comprising:

[0026] The digital model building module is used to draw the three-dimensional digital model of the standard thread profile of the screw, roller and nut according to the thread parameters of the planetary roller screw pair;

[0027] A meshing analysis module, used for performing meshing analysis on a partial threaded section of the lead screw or the nut and the roller in a simulation module of a three-dimensional software;

[0028] The simulation module includes an interference check function command, and the judgment parameter of the interference check function command is set to less than 0.000001mm. 3 ;

[0029] An adjustment module, for adjusting the tooth angle value of the first lead screw based on the meshing condition of the partial threaded segments of the first lead screw and the first roller in the standard planetary roller screw pair structure, so that the first lead screw and the first roller can optimize the mutual meshing position without interfering with the meshing; or

[0030] It is used to adjust the tooth angle value of the second nut based on the meshing condition of the partial threaded sections 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 optimize the mutual meshing position without interfering with the meshing.

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

[0032] The method for optimizing the design of the thread profile angle of a planetary roller screw pair in the present invention comprises the following steps: drawing a three-dimensional digital model of the standard thread profile of a screw, a roller, and a nut through three-dimensional software according to the thread parameters of the planetary roller screw pair; performing meshing analysis on a partial thread segment of the screw or the nut and the roller in a simulation module of the three-dimensional software; wherein 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 mm according to the actual simulation situation. 3; Based on the meshing of the partial thread segments of the first screw and the first roller in the standard planetary roller screw pair structure, the tooth angle value of the first screw is adjusted so that the first screw and the first roller can optimize the mutual meshing position without interfering with the meshing; or based on the meshing of the partial thread segments of the second nut and the second roller in the reverse planetary roller screw pair structure, the tooth angle value of the second nut is adjusted so that the second nut can optimize the mutual meshing position without interfering with the meshing. The thread tooth angle optimization design method of the planetary roller screw pair not only reduces thread wear, but also improves the load-bearing capacity, transmission efficiency, service life and safety factor of the planetary roller screw pair. The specific analysis is as follows:

[0033] 1. Improve the load-bearing capacity of the planetary roller screw pair. Whether in the standard planetary roller screw pair structure or the reverse planetary roller screw pair structure, if the part with inconsistent thread lead angle (the first screw in the standard structure and the second nut in the reverse structure) has its thread set to a 45° symmetrical tooth profile side angle, the meshing point will be very close to the top of the tooth of one of the meshing parts. The top of the tooth is the weakest point. When loaded, the stress at the bottom of the tooth will increase sharply, increasing the risk of fatigue fracture.

[0034] The thread profile angle optimization design method of the present invention adjusts the thread profile angle of the part with inconsistent thread lead angle so that the meshing point falls in the middle between the pitch circles of the two meshing parts, thereby more effectively exerting the high load-bearing characteristics of the planetary roller screw pair itself.

[0035] 2. Improve transmission efficiency. No matter in the standard planetary roller screw pair structure or the reverse planetary roller screw pair structure, after the thread profile angle of the part with inconsistent thread lead angle (the first screw in the standard structure and the second nut in the reverse structure) is optimized, the thread engagement point is moved to a better position, and the meshing circle diameter is changed, so that the meshing circle diameter ratio relationship between the screw, roller and nut is closer to the theoretical required value, thereby reducing the proportion of thread sliding friction during thread transmission, thereby improving transmission efficiency.

[0036] 3. Reduce thread wear. No matter in the standard planetary roller screw pair structure or the reverse planetary roller screw pair structure, after the thread profile angle of the part with inconsistent thread lead angle (the first screw in the standard structure and the second nut in the reverse structure) is optimized, the thread engagement point is moved to a better position, and the meshing circle diameter is changed, so that the meshing circle diameter ratio relationship between the screw, roller and nut is closer to the theoretical required value, and the proportion of sliding friction is reduced, that is, the degree of thread wear is reduced.

[0037] 4. Improve service life and safety factor. No matter in the standard planetary roller screw pair structure or the reverse planetary roller screw pair structure, after the tooth angle is optimized, under the same load condition, the stress on the bottom of the thread tooth is reduced and the degree of thread wear is reduced. These two points will directly improve the service life and safety factor. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 It is a schematic diagram of the process flow of the thread profile angle optimization design method of the planetary roller screw pair in an embodiment of the present invention;

[0039] Figure 2 Schematic diagram of the meshing structure of the roller and the lead screw or nut in an embodiment of the present invention;

[0040] Figure 3 It is a schematic diagram of the longitudinal cross-sectional structure of a standard planetary roller screw pair structure in an embodiment of the present invention;

[0041] Figure 4 It is a schematic diagram of a transverse cross-sectional structure of a standard planetary roller screw pair structure in an embodiment of the present invention;

[0042] Figure 5 It is a schematic diagram of the three-dimensional structure of the first roller and the first screw meshing before the standard planetary roller screw pair structure is adjusted and optimized in an embodiment of the present invention;

[0043] Figure 6 It is a schematic diagram of the three-dimensional structure of the meshing of the roller and the screw after the standard planetary roller screw pair is adjusted in the embodiment of the present invention;

[0044] Figure 7 It is a schematic diagram of the planar structure of the distance between the meshing point and the pitch circle of the standard planetary roller screw pair before and after adjustment in an embodiment of the present invention;

[0045] Figure 8 It is a schematic cross-sectional structural diagram of a planetary roller screw pair in an embodiment of the present invention;

[0046] Fig. 9 It is a schematic diagram of the three-dimensional structure of the meshing of the roller and the nut of the reverse planetary roller screw pair before adjustment in the embodiment of the present invention;

[0047] Fig.10 It is a schematic diagram of the meshing three-dimensional structure of the roller and the nut of the reverse planetary roller screw pair after adjustment in the embodiment of the present invention;

[0048] Fig.11 It is a schematic diagram of the planar structure of the distance between the meshing point and the pitch circle of the reverse planetary roller screw pair before and after adjustment in an embodiment of the present invention;

[0049] Fig.12 Schematic diagram of the structure of the thread profile angle optimization design system of the planetary roller screw pair in the embodiment of the present invention.

[0050] Description of reference numerals:

[0051] 10-Standard planetary roller screw pair structure;

[0052] 11-first nut; 12-first right gear ring; 13-first retaining frame; 14-first lead 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 lead screw; 221-lead screw thread; 222-lead screw gear; 23-second roller; 231-roller thread; 232-roller gear; 24-second retaining frame. DETAILED DESCRIPTION

[0055] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

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

[0057] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, it can also be the internal connection of two components, it can be a wireless connection, or it can be a wired connection. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0058] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0059] At present, the three core threaded parts of the planetary roller screw pair: screw, roller, nut, their tooth angles are generally designed to be symmetrical with both left and right tooth angles of 45°, such as Figure 2However, due to the inconsistency of the three thread lead angles, this design with 45° tooth angles does not ensure that the roller thread remains close to the pitch circle when meshing with the screw or nut, but rather very close to the tooth top, which leads to many disadvantages.

[0060] To solve the technical problem of poor thread engagement point position of rollers due to inconsistent thread lead angles in existing standard and reverse planetary roller screw pairs, please refer to Figure 1 As shown, an embodiment of the present invention provides a method for optimizing the thread profile angle of a planetary roller screw pair, and the design method comprises the steps of:

[0061] S1: Based on the thread parameters of the planetary roller screw pair, the 3D digital model of the standard thread profile of the screw, roller and nut is drawn using 3D software;

[0062] Wherein, the planetary roller screw pair includes a standard planetary roller screw pair structure and a reverse planetary roller screw pair structure;

[0063] 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;

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

[0065] S3: Based on the meshing condition of the partial threaded sections of the first lead screw 14 and the first roller 16 in the standard planetary roller screw pair structure 10, the tooth angle value of the first lead screw 14 is adjusted so that the meshing position of the first lead screw 14 and the first roller 16 is optimized without interfering with the meshing; or

[0066] Based on the meshing of the partial threaded sections of the second nut 21 and the second roller 23 in the reverse planetary roller screw pair structure 20, the tooth angle value of the second nut 21 is adjusted so that the second nut 21 and the second roller 23 can optimize the mutual meshing position without interfering with the meshing.

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

[0068] The thread profile angle optimization design method of the present invention adjusts the thread profile angle of the part with inconsistent thread lead angle so that the meshing point falls in the middle between the pitch circles of the two meshing parts, thereby more effectively exerting the high load-bearing characteristics of the planetary roller screw pair itself.

[0069] Secondly, whether in the standard planetary roller screw pair structure 10 or the reverse planetary roller screw pair structure 20, after the thread profile 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 engagement point is moved to a better position, and the meshing circle diameter is changed, so that the meshing circle diameter ratio relationship between the screw, roller and nut is closer to the theoretical required value, thereby reducing the proportion of thread sliding friction during thread transmission, thereby improving the transmission efficiency.

[0070] Third, whether in a standard planetary roller screw pair structure or a reverse planetary roller screw pair structure, after the thread profile 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 engagement point is moved to a better position, and the engagement circle diameter is changed, so that the proportional relationship of the engagement circle diameters among the screw, roller and nut is closer to the theoretical required value, and the proportion of sliding friction is reduced, that is, the degree of thread wear is reduced.

[0071] Fourthly, the service life and safety factor are improved. No matter in the standard planetary roller screw pair structure 10 or the reverse planetary roller screw pair structure 20, after the tooth angle is optimized, under the same load condition, the stress on the bottom of the thread tooth is reduced and the degree of thread wear is reduced. These two points will directly improve the service life and safety factor.

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

[0073] It is understandable that in 3D drawing software, as long as it has 3D simulation function, the optimization design of the thread profile angle of the planetary roller screw pair can be realized. In some other simulation software, when it has 3D simulation function, secondary development can be carried out and the above function can be realized.

[0074] For further information, see Figure 3 , Figure 4 As shown, the standard planetary roller screw pair structure 10 includes a first nut 11, a first right gear ring 12, a first retaining frame 13, a first screw 14, a first left gear ring 15, n first rollers 16, 2 locking screws 17 and 8 pins 18, wherein:

[0075] The first lead screw 14 is placed axially and horizontally; the first retaining frame 13 is sleeved on the outer wall of the first lead screw 14; n first rollers 16 are uniformly embedded in the first retaining frame 13 along the circumferential direction, the n first rollers 16 are all arranged parallel to the axis of the first lead screw 14, and the n first rollers 16 are all threadedly matched with the first lead screw 14; the first nut 11 is sleeved on the outer wall of the first retaining frame 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 sleeved on the outer walls of the n first rollers 16;

[0076] The first left gear ring 15 is correspondingly arranged at the axial left end position of the first roller 16; the first right gear ring 12 is correspondingly arranged at the axial 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 to the first nut 11 via a locking screw 17 and four pins 18 respectively; n is a positive integer.

[0078] Furthermore, in an embodiment of the present invention, the mean diameters of the first roller 16 and the first nut 11 are drawn according to the theoretical mean diameter values, the tooth angles of the first roller 16 and the first nut 11 are drawn symmetrically at 45 degrees, and the thread lead angles of the first roller 16 and the first nut 11 are the same; the tooth angle of the first lead screw 14 is drawn symmetrically at a corrected angle (not 45 degrees).

[0079] Embodiment 1:

[0080] When the planetary roller screw pair uses a standard planetary roller screw pair structure 10, as a preferred implementation of this embodiment, the specific model of the standard planetary roller screw pair structure 10 is 1806, and the screw pair parameters of model 1806 are as follows:

[0081] The thread median diameter of the first lead screw 14 is 18.9 mm;

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

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

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

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

[0086] Thread direction: all right-hand;

[0087] Number of thread starts: the first lead screw 14 and the first nut 11 both have 5 threads, and the first roller 16 has a single-thread start;

[0088] Lead: 6mm;

[0089] Pitch: 1.2mm.

[0090] Please refer to the specific structure as Figure 3 , Figure 4 As shown, the standard 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 axially horizontally placed and penetrated on the first nut 11, and two first retainers 13 are sleeved on the outer wall of the first screw 14 and are located on both sides of the interior of the first nut 11; the first retainer 13 serves as a limiting mechanism for the first roller 16, and in this embodiment, the first retainer 13 is set as an annular frame structure; the two first retainers 13 are axially horizontally coaxially placed on both sides of the first roller 16, and the annular frame structure is uniformly provided with n circular through holes along the circumferential direction, and each first roller 16 is correspondingly embedded in In a circular through hole, n first rollers 16 are uniformly embedded in the first retaining frame 13 along the circumferential direction, the n rollers 16 are all arranged parallel to the axis of the first screw 14, and the n first rollers 16 are all threadedly matched with the first screw 14; the first nut 11 is sleeved on the outer wall of the first retaining frame 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 sleeved on the outer walls of the n first rollers 16, the first left gear ring 15 is correspondingly arranged at the axial left end position of the first roller 16, and the first right gear ring 12 is correspondingly arranged at the axial right end position of the first roller 16; the first left gear ring 15 and the first right gear ring 12 are respectively fixed to the first nut 11 by a locking screw 17 and four pins 18; n is a positive integer, and 9≤n≤12.

[0091] The circumferential outer wall of the first lead 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 outer wall of the axial middle part and the outer walls of the axial ends of the first roller 16 are provided with external teeth; the threads in the middle part of the first roller 16 correspond to the threads of the first lead screw 14; the external teeth at the axial ends of the first roller 16 respectively mesh with the internal teeth of the first right gear ring 12 and the first left gear ring 15. When the first lead screw 14 rotates axially, the n first rollers 16 cooperate with the threads of the first lead screw 14 to realize the n first rollers 16 to perform planetary rotation around the first lead screw 14 and to perform axial movement relative to the first lead screw 14, thereby driving the first retainer 13 to rotate around the first lead screw 14 and to perform axial movement relative to the first lead screw 14.

[0092] The first right gear ring 12 and the first left gear ring 15 are placed with the same number of teeth and tooth phase; and the internal teeth of the first right gear ring 12 and the external teeth of the axially corresponding end of the first roller 16 have the same rotation direction; the internal teeth of the first left gear ring 15 and the external teeth of the axially corresponding end of the first roller 16 have the same rotation direction, so that the first nut 11 can perform synchronous rotation and translational motion relative to the first screw 14 driven by the first roller 16, and there is no relative axial movement between the first nut 11 and the first roller 16. The first nut 11 rotates one circle around the first screw 14, and the first nut 11 translates axially a lead distance relative to the first screw 14.

[0093] The first right gear ring 12 and the first left gear ring 15 are respectively fixedly connected to the first nut 11, and the relative rotation between the gear ring and the first nut 11 is limited by the locking screw 17 and the pin 18. During the installation process, the phase angle relationship of the gear rings at both ends is fine-tuned by adjusting the position of the gear ring relative to the first nut 11 to ensure that the left and right gear rings have the same phase angle.

[0094] The following design steps are performed on the standard planetary roller screw pair structure 10 using the planetary roller screw pair thread profile angle optimization design method:

[0095] Step S1: based on the thread parameters of the standard planetary roller screw pair structure 10, a standard thread profile 3D digital model of the first screw 14, the first roller 16, and the first nut 11 is drawn by Solidworkd software.

[0096] The median diameters of the first roller 16 and the first nut 11 are drawn according to the theoretical median diameter values, and the tooth profile angles are drawn according to 45° symmetrical tooth side angles. The thread lead angles of the first roller 16 and the first nut 11 are the same, and the first roller 16 and the first nut 11 can mesh at each other's pitch circles without interference. The tooth profile angle of the first lead screw 14 is also first drawn according to 45° symmetrical tooth side angles, and then optimized according to the meshing conditions.

[0097] Step S2: Select partial thread segments of the first lead screw 14 and the first roller 16 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 first lead screw 14 so that the first roller 16 and the first lead screw 14 can just achieve non-interference meshing.

[0098] 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 to be just in contact.

[0099] Step S3: Through adjustment, when the median diameter of the first lead screw 14 is 18.8455 mm, it is just engaged.

[0100] like Figure 5As shown, before adjustment, in the above steps S1-S3, it can be determined through the bad meshing results that the left tooth side angle of the first lead screw 14 needs to be increased, and the right tooth side angle needs to be increased, so that the meshing point can be continuously close to the middle position of the two pitch circles of the first roller 16 and the first lead screw 14. At this time, it can be simulated that the meshing point position of the first roller 16 and the first lead screw 14 is at points A and B. The distance between points A and B and the pitch circle of the first roller 16 is 0.012mm, and the distance between points A and B and the pitch circle of the first lead screw 14 is 0.045mm. It is obvious that the meshing point is very close to the tooth top position of the first lead screw 14 at this time.

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

[0102] For further information, see Figure 8 As shown, the reverse planetary roller screw pair structure 20 includes a second nut 21, a second screw 22 that moves linearly relative to the second nut 21, and a plurality of second rollers 23 disposed 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 screw gears 222 are provided on both sides of the screw thread 221; the middle part of the second roller 23 is provided with a roller thread 231 that matches the screw thread 221, and both ends are provided with roller gears 232 that match the screw gear 222; the inner wall of the second nut 21 is provided with a nut thread 211 that matches the roller thread 231, and both the screw thread 221 and the nut thread 211 are multi-start threads;

[0104] Two second retaining frames 24 are disposed on the second lead screw 22 . The second retaining frames 24 are evenly provided with a plurality of retaining holes along the circumferential direction. Both end portions of the plurality of second rollers 23 are rotatably connected to the plurality of retaining holes respectively.

[0105] For further information, see Figure 8 As shown, the mean diameters of the second roller 23 and the second lead screw 22 are drawn according to the corresponding theoretical mean diameter values, the tooth angles of the second roller 23 and the second lead screw 22 are drawn symmetrically at 45 degrees, the thread lead angles of the second roller 23 and the second lead screw 22 are the same, and the tooth angle of the second nut 21 is drawn symmetrically at a corrected angle (not 45 degrees).

[0106] Embodiment 2:

[0107] When the planetary roller screw pair uses a reverse planetary roller screw pair structure 20, as a preferred implementation of this embodiment, the specific model of the reverse planetary roller screw pair structure 20 is 1203, and the screw pair parameters of model 1203 are as follows:

[0108] The thread median diameter of the second lead screw 22: 12 mm;

[0109] The thread median diameter of the second roller 23: 6 mm;

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

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

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

[0113] Thread direction: the second lead screw 22 and the second nut 21 are right-handed threads, and the second roller 23 is left-handed threads;

[0114] Number of thread starts: the second lead screw 22 and the second nut 21 both have two threads, and the second roller 23 has a single-thread start;

[0115] Lead: 3mm

[0116] Pitch: 1.5mm.

[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 that moves linearly relative to the second nut 21, and a plurality of second rollers 23 that are arranged between the second nut 21 and the second screw 22 and are used to transmit torque to the second screw 22 so that the second screw 22 moves linearly. The inner wall of the second nut 21 is provided with a nut thread 211, and the nut thread 211 is a multi-start thread, which is used to cooperate with the second roller 23 to transmit torque; a plurality of second rollers 23 that are arranged along the circumference of the second screw 22 and a second retaining frame 24 that is sleeved on the second screw 22 and is located at both ends of the second roller 23; the outer wall of the second screw 22 is provided with a screw thread 221, and the screw thread 221 is a multi-start thread, which is used to cooperate with the thread of the second roller 23 to receive the torque transmitted by the roller, and the outer wall of the second screw 22 is provided with a screw thread 221. The screw thread 221 is a multi-start thread, which is used to cooperate with the thread of the second roller 23 to receive the torque transmitted by the roller. Screw gears 222 are provided on both sides of the rod thread 221, which are used to cooperate with the roller gear 232 structure on the second roller 23 to ensure that the second roller 23 performs planetary rotation around it; a roller thread 231 is provided in the middle of the second roller 23, and the roller thread 231 is a single-start thread, which cooperates with the threads on the second nut 21 and the second screw 22. Roller gears 232 are provided on both sides of the roller thread 231, which are used to cooperate with the screw gear 222. A clearance structure is also left between the roller thread 231 and the roller gear 232. The two ends of the second roller 23 are mating ends, which are used to cooperate with the second retaining frame 24. A plurality of retaining holes are evenly arranged on the second retaining frame 24 along the circumferential direction. The mating ends of the plurality of second rollers 23 are rotatably connected in the retaining holes one by one, and the second retaining frame 24 is sleeved on the second screw 22.

[0118] The following steps are used to design the thread profile angle optimization design method of the reverse planetary roller screw pair structure 20:

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

[0120] The mean diameters of the second roller 23 and the second lead screw 22 are drawn according to the theoretical mean diameter values, and the tooth angles are drawn according to 45° symmetrical tooth side angles. The thread lead angles of the second roller 23 and the second lead screw 22 are the same, and the second roller 23 and the second lead screw 22 can mesh at each other's pitch circles without interference. The tooth angles of the second nut 21 are also first drawn according to 45° symmetrical tooth side angles, and then optimized according to the meshing conditions.

[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 median 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 to be just in 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 Fig. 9 As shown, before adjustment, in the above steps S1-S3, it can be determined through the poor meshing results that the left tooth side angle of the second nut 21 needs to be increased, and the right tooth side angle needs to be increased, so that the meshing point can be continuously close to the middle position of the two pitch circles of the second roller 23 and the second nut 21. At this time, the meshing point position of the second roller 23 and the second nut 21 can be simulated at points C and D. The distance between points C and D and the pitch circle of the second roller 23 is 0.0148mm, and the distance between points C and D and the pitch circle of the second nut 21 is 0.068mm. It is obvious that the meshing point is very close to the tooth top position of the second nut 21 at this time.

[0125] like Fig.10 , 11 As shown, after adjustment, the median diameter of the second nut 21 needs to be adjusted to 24.0497 mm, and when the left and right tooth side angles of the second nut 21 are adjusted to 45.4° and 45.4° respectively, the meshing point is at points C′ and D′, and 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 time, the meshing point is just located in the middle of the two pitch circles of the second roller 23 and the second nut 21.

[0126] See also Fig.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 according to the thread parameters of the planetary roller screw pair;

[0128] A meshing analysis module 200, used for performing meshing 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 check function command, and the judgment parameter of the interference check function command is set to less than 0.000001mm. 3 ;

[0130] The adjustment module 300 is used to adjust the tooth angle value of the first lead screw 14 based on the meshing condition of the partial threaded segments of the first lead screw 14 and the first roller 16 in the standard planetary roller screw pair structure 10, so that the first lead screw 14 and the first roller 16 can optimize the mutual meshing position without interfering with the meshing; or

[0131] It is used to adjust the tooth angle value of the second nut 21 based on the meshing condition of the partial threaded sections of the second nut 21 and the second roller 23 in the reverse planetary roller screw pair structure 20, so that the second nut 21 and the second roller 23 can optimize the mutual meshing position without interfering with the meshing.

[0132] The specific definition of the thread profile angle optimization design system for planetary roller screw pairs can be found in the definition of the thread profile angle optimization design method for planetary roller screw pairs in the above text, which will not be repeated here. Each module in the above-mentioned thread profile angle optimization design system for planetary roller screw pairs can be implemented in whole or in part by software, hardware and their combination. The above-mentioned modules can be embedded in or independent of the processor in the computer device in the form of hardware, or can be stored in the memory of the computer device in the form of software, so that the processor can call and execute the operations corresponding to the above modules.

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

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, the 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 less than 0.000001mm. 3 ; S3: Based on the meshing condition of the partial threaded sections of the first lead screw and the first roller in the standard planetary roller screw pair structure, adjusting the tooth angle value of the first lead screw so that the first lead screw and the first roller can achieve the optimization of the mutual meshing position without interfering with the meshing; or Based on the meshing condition of the partial threaded sections of the second nut and the second roller in the reverse planetary roller screw pair structure, the tooth angle value of the second nut is adjusted so that the mutual meshing position of the second nut is optimized without interfering with the meshing.

2. The method for optimizing the thread profile angle of a planetary roller screw pair according to claim 1, characterized in that: 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 angle of a planetary roller screw pair according to claim 1, characterized in that: The standard planetary roller screw pair structure includes a first nut, a first right gear ring, a first retaining frame, the first screw, a first left gear ring, n first rollers, two locking screws and eight pins; The first screw is placed axially and horizontally; the first holder is sleeved on the outer wall of the first screw; n first rollers are uniformly embedded in the first holder along the circumferential direction, the n first rollers are arranged parallel to the axis of the first screw, and the n first rollers are threadedly matched with the first screw; the first nut is sleeved on the outer wall of the first holder; 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 angle of a planetary roller screw pair according to claim 3, characterized in that: The median diameters of the first roller and the first nut are drawn according to the theoretical median diameter values, the tooth angles of the first roller and the first nut are drawn symmetrically at 45 degrees, the thread lead angles of the first roller and the first nut are the same; the tooth angle of the first screw is drawn symmetrically according to the corrected angle.

5. The method for optimizing the thread angle of a planetary roller screw pair according to claim 1, characterized in that: 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 lead screw is provided with a lead screw thread, and lead screw gears are provided on both sides of the lead screw thread; the middle part of the second roller is provided with a single-start thread matched with the lead screw thread, and both ends of the second roller are provided with roller gears matched with the lead screw gear; the inner wall of the second nut is provided with a nut thread matched with the single-start thread, and both the lead screw thread and the nut thread are multi-start threads; The second screw is provided with a second retaining frame, and the second retaining frame is evenly provided with a plurality of retaining holes along the circumferential direction, and both end portions of the plurality of second rollers are rotatably connected to the plurality of retaining holes respectively.

6. The method for optimizing the thread profile angle of a planetary roller screw pair according to claim 5, characterized in that: 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.

7. A planetary roller screw thread angle optimization design system based on the method according to any one of claims 1 to 6, characterized in that: The design system includes: The digital model building module is used to draw the three-dimensional digital model of the standard thread profile of the screw, roller and nut according to the thread parameters of the planetary roller screw pair; A meshing analysis module, used for performing meshing analysis on a partial threaded section 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 less than 0.000001mm. 3 ; An adjustment module, for adjusting the tooth angle value of the first lead screw based on the meshing condition of the partial threaded segments of the first lead screw and the first roller in the standard planetary roller screw pair structure, so that the first lead screw and the first roller can optimize the mutual meshing position without interfering with the meshing; or It is used to adjust the tooth angle value of the second nut based on the meshing condition of the partial threaded sections 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 optimize the mutual meshing position without interfering with the meshing.

Images