CN-122020916-A - Multi-performance coordination design method for planetary roller screw

CN122020916ACN 122020916 ACN122020916 ACN 122020916ACN-122020916-A

Abstract

The invention relates to a multi-performance coordination design method for a planetary roller screw, and belongs to the technical field of planetary roller screws. The method comprises the steps of firstly establishing a thread meshing point slip ratio and a maximum von Miss stress calculation model based on a planetary roller screw kinematics and load distribution model, secondly establishing an equality and inequality structure constraint condition according to the accurate meshing, structure non-interference and contact boundary conditions of the planetary roller screw, thirdly establishing a planetary roller screw multi-performance optimization design model according to an optimization target and the constraint condition, fourthly solving the planetary roller screw multi-performance design model by adopting a multi-target genetic algorithm to obtain a pareto front edge and corresponding structure design parameters, and fourthly obtaining the pareto front edge range meeting the limit balance cost according to the given limit balance cost. Based on Euclidean norms and minimizing dimensionless distance, the optimal weighing solution and the corresponding structural design parameters are obtained.

Inventors

PU WEI
WANG ZONGZHENG
CAO WEI
ZHOU XUE
ZHANG YIN
LIU YUEHANG

Assignees

四川大学

Dates

Publication Date: 20260512
Application Date: 20260413

Claims (8)

1. The multi-performance coordination design method for the planetary roller screw is characterized by comprising the following steps of: Step 1, establishing a slip ratio calculation model and a maximum Fengmi Sies stress calculation model of a thread engagement point based on a kinematic model and a load distribution model of a planetary roller screw, wherein the slip ratio is a quantitative representation index of friction performance, and the maximum Fengmi Sies stress is a quantitative representation index of bearing performance; Step 2, establishing an equality structure constraint condition and an inequality structure constraint condition according to the correct engagement, structure noninterference and contact boundary conditions of the planetary roller screw; step 3, establishing a planetary roller screw multi-performance optimization design model by combining the equality structure constraint condition and the inequality structure constraint condition by taking the minimum slip ratio and the maximum Fengmi Sauss stress as optimization targets; Step 4, solving the multi-performance optimization design model by adopting a multi-objective genetic algorithm to obtain the pareto front edge and the corresponding planetary roller screw structure design parameters about friction performance and bearing performance; and 5, determining the pareto front range meeting the limit weighing cost according to the given limit weighing cost, and solving to obtain the optimal weighing solution of the friction performance and the bearing performance and the corresponding planetary roller screw structure design parameters based on the Euclidean norm and minimizing the dimensionless distance.
2. The method for coordinated design of multiple performances of a planetary roller screw according to claim 1, wherein when the calculation model of the slip ratio is built in step 1, the cage of the planetary roller screw is preset to be stationary, at this time, the screw, the roller and the nut are only rotated relative to the cage, and the side angles of the roller and the nut are set to be equal, only the contact sides of the screw and the roller have slip, and the slip ratio calculation formula of the thread engagement point is derived by calculating the slip velocity vector and the absolute velocity vector at the contact point of the screw and the roller.
3. The method for designing the planetary roller screw rod with coordinated performances according to claim 2, wherein when the load distribution model is built in the step 1, a load distribution matrix equation is built based on the inter-thread deformation coordination and force balance relation, the load distribution matrix equation is solved by adopting a Newton iteration method, a load distribution matrix of a thread contact point is obtained, then the contact load distribution and the contact geometry are combined, fengmi Sauss stress of the thread engagement point is obtained through calculation, and then the maximum Fengmi Sauss stress of all the thread engagement points is extracted.
4. The method for designing the planetary roller screw multi-performance coordination according to claim 1, wherein the equation structure constraint condition in the step 2 comprises no relative axial displacement between the roller and the nut, coincidence of rotation centers of a roller thread pair and a gear pair, no mutual interference of adjacent rollers and maximum bearing capacity, and the inequality structure constraint condition comprises no geometric interference of a roller and a nut spiral line, and retention of screw-roller and roller-nut side contact points in thread boundaries and clearance allowance.
5. The method for coordinated design of multiple performances of a planetary roller screw according to claim 1, wherein in the step 5, when the pareto front is subjected to dimensionless treatment, the friction performance and the bearing performance are equally important, and the pareto front value corresponding to the screw side angle of about 45 degrees is adopted as the dimensionless parameter, so that all data points of the pareto front are subjected to dimensionless conversion.
6. The method for coordinated design of multiple performances of a planetary roller screw according to claim 5, wherein in the step 5, 8-order gaussian functions are adopted to perform curve fitting on dimensionless pareto front data points, the fitted curve is derived, and a lower limit of a boundary slope of the dimensionless pareto front is obtained according to a given limit weighting cost c (c < 0) And upper limit of And determining a dimensionality pareto front range meeting the limit weighing cost according to the boundary slope.
7. The method for coordinated design of multiple performances of a planetary roller screw according to claim 6, wherein in the step 5, the pareto front meeting the limit weighing cost is re-dimensionalized by adopting a max-min method, a dimensionless distance calculation model is built based on euclidean norms, and the optimal weighing solution and the corresponding structural design parameters are obtained by minimizing the dimensionless distance solution.
8. The method for coordinated design of multiple performances of a planetary roller screw according to claim 1, wherein the structural design parameters of the planetary roller screw include screw, thread flank angle of rollers and nuts, nominal radius of screw threads, thread head number of screws and nuts, thread pitch, and number of roller threads.

Description

Multi-performance coordination design method for planetary roller screw Technical Field The invention belongs to the technical field of planetary roller screws, and particularly relates to a multi-performance coordination design method of a planetary roller screw. Background The planetary roller screw is a new generation high-end linear driving mechanism, and realizes high power density, high reliability and high precision conversion of rotation and linear motion through planetary motion of a large number of meshing threads and a plurality of rollers. The current rapid development of electrified technology is accelerating to replace traditional hydraulic systems with efficient, environmentally friendly electromechanical servo systems. Under the background, the planetary roller screw is increasingly widely applied to the fields of electromechanical servo systems for aircraft wing surface control, feeding systems of numerical control machine tools, linear joints of humanoid robots and the like. The planetary roller screw transmits motion and power through threads, and the screw and roller thread meshing interface has a large sliding speed, so that surface abrasion can be accelerated, and transmission efficiency is remarkably reduced. In addition, a complex deformation coordination relationship exists between adjacent meshing threads, so that the load distribution among the contact threads is obviously uneven, and the bearing performance of the contact threads is reduced. Friction performance and bearing performance are key evaluation indexes of the planetary roller screw, and the comprehensive improvement design of the two performances has decisive effects on realizing high efficiency, low abrasion, small volume and long service life. Because of the one-to-one mapping relation between the structural parameters and the bearing performance and the friction performance of the planetary roller screw, developing the structural optimization design of the planetary roller screw has important significance for improving the comprehensive performance of the planetary roller screw. However, the existing planetary roller screw design methods are mainly designed for bearing performance, and lack a coupling design method for friction performance, particularly for the coupling design method with the bearing performance. In addition, there is an undisclosed constraint relationship between friction performance and load bearing performance, and there is no effective design method capable of coordinating the two performances. Therefore, the development of the planet roller screw multi-performance coordination design method has important practical application value for realizing the comprehensive improvement of friction and bearing performance. Based on the background, the invention provides a planet roller screw multi-performance coordination design method. The method takes the slip ratio and the maximum von mises stress as quantitative characterization indexes of friction performance and bearing performance respectively. The optimal friction and bearing performance and the corresponding structural design parameters are obtained by taking the planetary roller screw sliding-rolling ratio and the maximum von mises stress as optimization targets and taking the structural constraint of equality and inequality as constraint conditions and adopting a multi-target genetic algorithm and an optimal weighing solution calculation method. The invention can realize the coordinated design of multiple performances of the planetary roller screw, thereby remarkably improving the comprehensive performance of the planetary roller screw. Disclosure of Invention The invention provides a multi-performance coordination design method of a planetary roller screw, which is used for solving the technical problem of limitation of the existing planetary roller screw taking single performance as a design target. In order to achieve the above purpose, the present invention is realized by the following technical scheme: A multi-performance coordination design method of a planetary roller screw comprises the following steps of 1, establishing a sliding ratio calculation model of a thread engagement point and a maximum Fengmi Sies stress calculation model based on a kinematic model and a load distribution model of the planetary roller screw, wherein the sliding ratio is a quantitative representation index of friction performance, the maximum Fengmi Sies stress is a quantitative representation index of bearing performance, 2, establishing an equality structure constraint condition and an inequality structure constraint condition according to correct engagement, structure non-interference and contact boundary conditions of the planetary roller screw, 3, establishing a planetary roller screw multi-performance optimization design model by taking the sliding ratio and the maximum Fengmi Sies stress as optimization targets and combining the equality structure constra