Research On The Residual Stress Of The Casting Of Vermicular Graphite Iron Clutch Pressure Plate

The residual stress inside the casting often has an adverse effect on machining and subsequent assembly use.For example,the residual stress directly affects the strength,fatigue limit and rigidity of the parts and other important properties,but also affects the dimensional accuracy of the parts and the service status of the parts,thereby reducing the service life of the parts.Therefore,it is necessary to study the causes,influencing factors and the hazards of residual stress to the parts,and take appropriate measures to reduce the residual stress on the basis of the research work.This article takes the GGV30 vermicular graphite cast iron automobile clutch pressure plate castings produced by a certain enterprise as the research object,and conducts a series of studies on the generation and elimination of pressure plate casting residual stress,which provides a theoretical basis for guiding actual production.The main research contents are as follows:(1)Use UG software to carry out three-dimensional modeling of pressure plate castings,set the casting process parameters according to the original process plan provided by the factory,use ProCAST finite element software to simulate the casting process of the pressure plate,and obtain the temperature field of the pressure plate casting casting process,Stress field and deformation field data.(2)Detailed analysis of the temperature field changes in the three processes of filling,solidification and cooling of the casting;the solidification characteristics of the casting are from the inner and outer rings of the platen to the middle of the plate,and the radial area of the large lug is a small range of sequential solidification of the inner ring along the direction of the riser;finally,according to the changes in the temperature field to study the residual stress field and the deformation displacement of the casting,it is found that the deformation displacement of the casting in the radial direction is the displacement of the outer ring toward the inner ring,and With the closer to the inner circle the deformation displacement is smaller,but has a cumulative effect,and the deformation in the thickness direction is extrusion type in the middle from the front and back of the platen;the stress distribution on the platen surface is not uniform,and the stress in the inner circle part opposite to the small lug is large,and the radial stress of the platen is analyzed in detail,and it is concluded that the stress in the inner circle is generally much larger than that in the outer circle,and the size of the stress value on the plate surface is between the two.The radial stresses in the small lug region differed greatly,and the radial stresses in the large lug region differed less.(3)the method of blind hole is used to measure the residual stress in the die-plate casting.By comparing the simulation results with the test results,it is found that the simulation results are consistent with the test measurement in the law of stress change,although the stress property is contrary to the test result,the numerical value is close,even if there is some deviation,the deviation is small in the allowable error range,so the result of numerical simulation is reliable.Finally,the reason of the difference between the measured value and the simulation value is analyzed.(4)the effects of natural aging,chemical composition(carbon equivalent and Si/C ratio),casting process parameters(pouring temperature and falling sand temperature)and pouring process plan on the residual stress of castings are studied,it was found that higher pouring temperature(1420 °C),lower shakeout temperature(less than300 °C),higher carbon equivalent(4.64%)and higher Si/c ratio(0.73)could reduce residual stress effectively.The theoretical basis and technical support are provided for the actual production of low stress die-plate castings.