| In the manufacturing process of the ball screw,the consistency of the product is difficult to be guaranteed due to the influence of processing errors.With the increasing demand for the precise ball screws in the manufacturing industry,new challenges have occurred in the high assembly accuracy and assembly efficiency.Because it takes a long time to assemble the ball screw and the assembly accuracy is uncontrollable,the application of computer intelligence technology can effectively reduce manual intervention and operation.This article conducts the theoretical and experimental research on key factors such as load distribution,preload,friction coefficient and rigidity that affect the assembly quality of the ball screw.Combined the friction torque measuring system with the rigidity measuring system,this paper proposes a method for efficient assembly of the ball screw.The software system is used to select and match the auxiliary parts of the ball screw.The specific research content is as follows:(1)The load distribution model of the double nut ball screw is established.This paper takes the effects of ball size error,raceway tooth profile error,the lead error and screw pitch error into consideration.When one end of the ball screw is fixed and the other is supported,the double-nut ball screw(subject to overturning moment)is modelled.Further,the influence of axial load,geometric error,and turning torque on the load distribution of the double-nut ball screw is analyzed,which provides a theoretical foundation for friction torque calculation and rigidity calculation.(2)A calculation model for the preload of the double-nut ball screw is proposed.Under the deformation of the screw and nut,the coordinated relationship of the size and deformation of each part of the screw,nut and ball is established.The relationship between the preload and the thickness of the gasket,rigidity,and the ball’s number is obtained,and the influence of the thickness of the gasket and the number of balls is analyzed on the preload,which provides a theoretical foundation for the construction of the matching function of the ball screw.(3)The friction coefficient measuring test of the ball screw under different working conditions is carried out.In the previous situation,the friction coefficient is taken from the empirical value to calculate the friction torque.A preload adjustable device is optimized to realize the simultaneous online measurement of the preload and the friction torque under different speeds and different preload levels.The friction coefficient of the ball screw under different lubrication conditions can provide real and feasible data for the calculation of the preload and friction torque.(4)The rigidity measuring tests of the ball screw are carried out.Due to the lack of experimental verification in the theoretical model of load distribution in Chapter 2,a rigid test bench independently is used to conduct a rigid test of the ball screw under axial load to measure the axial displacement of the ball screw.The test results and theoretical results are compared and analyzed to verify the correctness of the model,and the influence of the ball diameter on the rigidity is analyzed.(5)A software system for efficient assembly of ball screws is developed.The software system consists of the software of the intelligent matching system of the ball screw subcomponents,the key geometric size information database of the screw,nut,and ball.The matching degree function with the precise control of the preload is proposed as the main objective.Through the analysis of all parts,the function results are useful to complete the best matching of parts. |
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