The residual stress on the grinding surface plays a vital role in various properties of the workpiece. It has an important impact on the fatigue strength, dimensional accuracy stability and stress corrosion resistance of the spiral bevel gear. It is directly related to the production qualification rate and service life of the spiral bevel gear. It is an important standard to judge the excellent performance of the spiral bevel gear. For spiral bevel gear, improper control of residual stress will deform the tooth surface, cause tooth surface error and affect the meshing transmission of spiral bevel gear. Appropriate residual compressive stress can improve the fatigue strength of the workpiece. When the residual tensile stress is too large and higher than the fatigue limit that the workpiece can bear, grinding cracks will appear on the surface and seriously affect the service life of spiral bevel gear. Therefore, in order to solve the grinding quality problems that may occur in the processing and production of spiral bevel gears, improve the product qualification rate and drive the improvement of spiral bevel gear manufacturing technology, it is urgent to carry out the research on the surface residual stress of spiral bevel gears.
Aiming at the transformation of surface residual stress of spiral bevel gear steel 30CrMnTi after grinding, firstly, the formation mechanism of grinding residual stress is studied and analyzed, and then the variation law of surface residual stress with cutting distance and surface residual stress with layer depth after grinding is obtained by using ANSYS finite element analysis software based on stress thermal coupling theory, The actual value of surface residual stress after grinding is measured by X-ray stress meter through experimental method, and compared with the simulation results to verify the effectiveness of the simulation model. Finally, the variation law of surface residual stress under different grinding parameters and cooling conditions is studied. The results show that:
(1) There are many factors that cause the change of surface residual stress in the grinding process of spiral bevel gear steel. The main reason is the comprehensive result of residual compressive stress caused by grinding cutting extrusion and residual tensile stress caused by grinding thermal stress.
(2) The residual stress of the surface layer of spiral bevel gear steel after grinding can be effectively simulated through the mechanical thermal coupling theory. At the grinding speed vs = 20.3 M / s and the grinding depth AP = 50 μ m. Under the grinding condition of workpiece speed VW = 1200 mm / min, the grinding surface of spiral bevel gear steel is in the state of tensile stress, and the maximum value of residual tensile stress is about 123 MPa. The tensile stress gradually changes into compressive stress along the layer depth, and reaches the maximum value at 0.19 mm. The maximum value of residual compressive stress is about 119.6 MPa. With the increase of depth, the value of compressive stress gradually decreases and tends to zero.
(3) Residual stress on grinding surface of spiral bevel gear steel σ From the original stress of blank surface layer σ 0 and residual stress during grinding Δσ It consists of two parts. The variation trend of residual stress on the surface of the workpiece before and after grinding of spiral bevel gear steel is measured by X-ray stress measurement combined with electrolytic polishing. The residual stress on the original workpiece surface is about – 225 MPa, and the maximum value of residual compressive stress is obtained at the depth of about 0.4 mm-0.5 mm, which is about – 360 MPa. Then the residual stress in the grinding process of spiral bevel gear steel is calculated Δσ Compared with the simulation data, the results show that the simulation can reflect the change law of the test results to a certain extent, and verify the effectiveness of the simulation model.
(4) Residual compressive stress on grinding surface of spiral bevel gear steel σ Under the condition of dry grinding, it decreases gradually with the increase of grinding depth or grinding speed of spiral bevel gear steel, and increases slightly with the increase of workpiece speed. Under the condition of wet grinding, the compressive stress caused by the grinding force of spiral bevel gear steel plays a leading role. With the gradual increase of the grinding depth of spiral bevel gear steel, the value of residual compressive stress increases gradually.