| For the National Science and Technology Major Project ‘The CNC Machine Tools’ Key Functional Components Reliability Growth Project’,the theoretical analysis,measuring method,and measuring device for the transmission efficiency of ball screws are conducted in this paper.This research fills the lack of the special equipment of the ball screw under the actual working conditions in China,and meet the industry’s demand for the detection of ball screws’ transmission efficiency.The calculation method for the transmission efficiency accepted in major ball screw mechanism manufacturer ignores the effect of the actual working conditions.Thus,a transmission efficiency calculation model considering the structural parameters,speed,load,and the friction coefficient is proposed,and the influence of each parameter on the transmission efficiency is analyzed.Compared with the traditional calculation formula based on the inclined plane model to calculate transmission efficiency,the accuracy and reliability of the transmission efficiency calculation formula proposed in this paper are proved.This paper compares and analyzes the basic formula for the transmission efficiency of the ball screw and determines the measuring principle for the transmission efficiency.Based on the measuring principle,the main measuring parameters and sensors’ types are determined.Then completing the construction of the test system.According to the overall design requirements of the test bench,the measuring system consists of the mechanical system,the detection system,and the control system.The mechanical system design of the test bench mainly includes the bed,the parts installed on the bed,and the measuring parts for the axial force of the nut.The control system can conduct the motion switching between the forward and reverse transmission of the ball screw.The detection system can collect the data during the operation of the ball screw and calculate the transmission efficiency.The accuracy analysis of the measuring device for the transmission efficiency of the ball screw mainly includes the equipment manufacturing error and the component installation error.The Abbe error calculation formula is used to obtain the overall accuracy of the measuring device.And a preliminary experiment to obtain the transmission efficiency of the ball screw is conducted to evaluate the uncertainty and repeatability of the measuring system,which proves that the measuring data of the test bench is valid and reliable.The dynamic transmission efficiency tests are carried out in terms of the double nut 4010 ball screw.Compared with theoretical results from the proposed efficiency calculation model considering the actual working conditions,the influence of actual working conditions on the transmission efficiency of the ball screw is analyzed,which verifies the validity of the proposed calculation model.Finally,the best friction coefficient of the ball screw is determined by the transmission efficiency test and the transmission efficiency calculation formula.For the selecting and designing calculations of practical engineering,the transmission efficiency calculation model proposed in this paper can effectively estimate the efficiency according to the working conditions. |
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