Die Wear Analysis And Experiment Results Of The Wear Tester Oriented To Fine-blanking

Fine-blanking,a precision forming process,is developed on the basis of conventional blanking.The theoretical basis is that better plastic forming properties can be achieved under high hydrostatic pressure for metals.During the fine-blanking process,the initiation and propagation of crack can be inhibited in shearing zone of the sheet under larger hydrostatic pressure.Therefore,fine-blanking parts can be assembled directly,which have high perpendicularity and smooth surface.However,the die works under the condition of large friction and high alternating extrusion pressure,accompanied with the thermal effect caused by friction,the service life of the punch would be shorten.Therefore,it is significant to predict the wear condition and die-changing time of the punch in fine-blanking process.In view of the problems above,a method of designing sheet extrusion tool was proposed based on the finite element(FE)analysis to study the punch wear of fine-blanking,which was also verified by the experiment of sheet extrusion.The main contents are summarized as follows:According to the FE simulation of shearing process during fine-blanking and the Archard wear model,the punch wear was analyzed from the aspect of normal pressure aspect and material flowing.The reason of wear in different positions of the punch was summarized.The result shows the wear at the cutting edge of punch is most serious,and it will be destroyed firstly.Fine-blanking experiment is the most direct way to study the wear mechanism of punch in fine-blanking.Due to the complexity of the process and the precision requirement for press and die,the wear experiment in laboratory needs dismounting and assembly for many times,but the accuracy of die assembly cannot be guaranteed,which will affect the wear results.Based on the punch wear condition in fine-blanking,a V-shaped pin-on-sheet model and a sheet extrusion tool were designed to study the wear in fine-blanking.DEFORM was adopted to simulate the pressure and material flowing of the two models and fine-blanking in the forming process,and the comparison shows that the wear condition of the two models and the fine-blanking tool is similar,which means that they can be used for the research of the punch wear.The merits and drawbacks of the two models are compared,and the sheet extrusion is chosen as the way for further study.Then,a sheet extrusion tool with blankholder was designed and the experimental verification was carried out.The extrusion part was analyzed from the die roll and the shearing surface.The sheet was etched circular grid by using pad printing method,then the sheet extrusion experiment was carried out by using it.The material flow in the process of extrusion along the cutting edge was measured quantitatively,the values and rules of the material flowing are summarized for different positions.The experiment of sheet extrusion was carried out for thousands of times,and the profile of the tool at the cutting edge was measured at different extrusion times,and the profile evolution curve was fitted and analyzed.