Research On The Micro Deformation Of The Fine-blanking Tool Working Parts Caused By Temperature And Load

Fine-blanking is an advanced precise plastic forming technology, which can be used to process parts with high quality. Based on these satisfactory advantages, fine blanking has been widely used in many industrial fields. The clearance of fine-blanking tool are smaller than that of traditional stamping. It is usually 1%-0.5% of the sheet thickness. The sheet deforms greatly in a minimal space and generates a lot of heat. It makes the temperature of punch and die goes up and leads to deformation. Cutting edge bears heavy load which leads to deformation. Both of them will lead to real change in the key design parameters, such as the clearance between punch and die. Inappropriate gap not only affects the forming quality of the parts, but also can cause premature wear failure. The service life of the tool is reduced. The paper focuses on this.Firstly, in order to reveal the influence of temperature variation on the die, the coupling simulation of transient structure and transient heat by finite element method is used, 3D models are developed for the analyses of structure and temperature field. The distribution of temperature field in tool under the stamping cycle is investigated. The deformation of tool in this temperature field is calculated. The tool during stamping is measured by infrared thermal imager. The data obtained are consistent with the simulation results. The results indicate that while the B9 ratchet wheel progressive die stamping, cutting edge temperature of the punch and die in the third place reaches 135 degree Celsius and the clearance between the punch and die is reduced by 36% than that by design due to heat expansion. The change of the clearance needs to be considered in the design of the tool.Secondly, in axial direction, the punch of fine-blanking is suffered from blanking force, counter force and frictional force. In radial direction, the punch of fine-blanking is suffered from extrusion force. The force condition is extremely complex. Cutting edge is the region that the punch shears the sheet. The force condition is even worse. In the stamping process, cutting edge occurs chipping. By observing the failure of punch, we found a crack in the side wall of the punch. It causes the chipping of the punch. Plastic deformation and wear were also found at the cutting edge. The results of finite element simulation show that the punch in the side wall prone stress concentrations that can lead to crack. Plastic deformation did occur at the cutting edge because of high load. In order to improve the stress condition of the cutting edge, six different chamfers are designed and analyzed by finite element method. Compared the deformation and stress distribution of design chamfers and traditional chamfer, a specific chamfer of cutting edge is founded which can improve the stress situation.All the researches in this paper are from a project cooperating with a domestic famous fine-blanking leading enterprise. The research results have been delivered to the enterprise for practical production.