Development Of Ring-block Friction Testing Machine With Dynamic Working Parameters

As an important part of tribology research,tribology testing machine plays a key role in the test results due to its working condition and measurement structure.At present,the movement and contact modes of the ring-block friction testing machines developed by domestic universities and enterprises are mostly constant,and the working parameters are not changed in the test.But the friction forms of moving devices such as plunger,bearing and rim are generally complex.The parameters such as load,contact mode and temperature will often undergo dynamic change process.If the traditional testing machine is used for testing,the results can be used for reference value of the final engineering application,and it needs to be verified again through bench test,Therefore,we need a friction tester to realize more changeable sample movement and contact mode,and use the combination of various modes to realize dynamic working conditions,so as to combine the advantages of simulation bench test with the common ring-block friction tester to some extent,so as to evaluate and study the friction performance of materials more objectively.In this paper,the traditional ring-block friction and wear tester is taken as the prototype,and the dynamic ring-block friction tester is designed,and it is taken as the research object,and a complete set of design ideas and specific implementation schemes are put forward1)The technical specifications and functional requirements of ring-block friction testing machine with dynamic working parameters are determined.The main components of the tester are preliminarily determined.The design scheme and measurement principle of the overall structure of the tester are proposed,and the logical framework of the measurement and control system is finalized.2)The detailed design of mechanical structure of the testing machine is carried out,including the specific scheme and modeling of the loading device,sample ring driving device,friction measurement mechanism,fixture and sample,sample lubrication device,etc.at the same time,the selection and calculation of key standard parts such as motor,loading spring,screw rod,slide rail,etc.are carried out in detail.3)After the design of the main mechanical mechanism of the testing machine,a set of suitable measurement and control system is designed according to its structure,and the measurement principle and method of physical quantity are given;according to the design index,the configuration mode of software and hardware of the motion control system is given,and the selection of various controllers,sensors and amplifiers is given;the main circuit of the tester and the peripheral control circuit of servo motor are drawn;The motor control logic and the upper computer program of PID algorithm in the loading process are proposed,and the realization scheme of dynamic working condition under PLC control is given.4)According to the configuration scheme of the measurement and control system,a set of data acquisition system is designed by LabVIEW.The selection,setting and communication method of the acquisition card are given.The program framework of the upper computer data acquisition system is proposed.The PLC communication,collection process and data storage program are completed,and the interaction needs in the normal test process can be met.5)The acceleration and deceleration mode of dynamic operation is studied,and the algorithm and implementation scheme of S-type acceleration and deceleration curve based on PLC motion control command are proposed.BP neural network and PID algorithm are introduced to realize adaptive parameter adjustment.The relevant algorithm is given and simulated by the mathematical model of the testing machine.The advantages of BP neural network and PID algorithm are shown by comparison.6)The prototype is built.Three groups of identical samples are used to test the combined dynamic condition on the actual prototype.The repeatability of the testing machine is tested,which proves that the stability of the testing machine meets the requirements.7)The paper summarizes and prospects,analyzes the shortcomings and defects of the testing machine,and puts forward the direction of rectification and implementation ideas in the future.