Development Of High-speed Scratch Test Method And Device For Single-particle Nano-cutting Depth

Hard-and-brittle materials are widely used in aerospace,electrical and electronic,optics,biomedicine,solid-state lasers and other fields due to their excellent properties such as high hardness,low thermal expansion coefficient,and stable chemical properties.At the same time,hard-and-brittle materials are typical difficult-to-machine materials due to their high brittleness and low fracture toughness.At present,grinding is one of the most important ways to process hard-and-brittle materials,but grinding often causes surface and sub-surface damage to the surface of machined parts.The research on single-tip tool scratch test is the basis for exploring the removal mechanism and damage of hard-and-brittle materials,which has great guiding significance for the realization of plastic domain removal and surface quality improvement of hard-and-brittle materials.However,the traditional single-particle scratching test device is difficult to take into account the high speed and stable nano-cut depth.At the same time,it is also difficult to control the scratch length,and it is difficult to achieve a one-to-one correspondence between the collected force signal data and the scratch topography position.In this paper,a new single-particle scratching test platform is designed in view of the limitations of the above single-particle scratching test.The mechanical properties analysis and structure optimization are carried out,and the functions of information acquisition and storage,motion control,and intelligent feedback are developed and compiled based on Lab VIEW.A well-developed test platform was used to conduct scratch tests on two common hard and brittle materials,single crystal silicon and fused silica.The main research contents are as follows:(1)The mechanical characteristics of the scratch test setup that has been built are analyzed,and the theoretical natural frequency and actual natural frequency of the scratch test setup are obtained through simulation and excitation experiments.(2)The "Lab VIEW" software is used to re-develop and compile the data acquisition,reading,real-time storage,and motion control functions of the scratch test bench,so that all test operations can be completed in an optimized and integrated Lab VIEW " VI " interface.At the same time,the intelligent motion feedback control function is added,and the scratch threshold is set according to the critical load of the material to avoid repeated scratches and damage to the overall scratch characteristics due to too deep scratches.(3)According to the different shapes of hard-and-brittle material workpiece,the corresponding scratching method is designed,and the required parameters are designed through simulation and theoretical calculation.A perfect single-particle scratching test platform was used to carry out scratching tests on two kinds of workpiece respectively.The feasibility of different workpiece shape scratch methods was verified by the characterization test results,and the usability evaluation test of scratching test platform was completed after development and improvement.(4)Through the single-particle scratch test,the anisotropy difference of the upward elastic recovery coefficient and the depth of the ductile-brittle transition,the sensitivity of the elastic recovery coefficient of molten quartz and the depth of the ductile-brittle transition to the rate were studied under the conditions close to the actual grinding process.