What are the characteristics of thin and thick plate stamping? How to punch small holes in the thick plate?
What are the characteristics of thin plate and thick plate stamping? How to punch small holes in the thick plate? The thickness of the plate is relative. In the relevant standards, the plate above 4 mm is called the thick plate, and the plate below 4 mm is called the thick plate. The material is called a thin plate. (1) The stamping of thin plates has the following characteristics: 1) The stamping gap of the die is small. The reasonable gap of the stamping die is based on the overlap of the upper and lower cracks when the sheet is broken. The smaller the thickness of the punched sheet, the smaller the projection length of the crack on the surface, and the smaller the gap of the punching die used. 2) Thin-material stamping parts have larger springback but better cross-section quality. Thin material has a large deformation during stamping. When the stamping is completed, the workpiece must return to its original shape and produce greater springback. However, due to the small stamping gap and sheet thickness, the resulting stamping section is perpendicular to the surface, the section is bright and wide, and the composition of the section is not easy to distinguish, and the quality of the section is better. 3) The characteristics of the thin plate stamping die The gap of the thin plate stamping die is small. When the punching die adopts the ordinary stamping die structure, the mold base used is required to have high accuracy, and the guide pin and guide sleeve of the mold base should be matched to H6/h5. , The guide sleeve should not be detached. And the use of floating mold handle and ball guide sleeve structure. In order to make the gap between the convex and concave molds can be adjusted during the working process, the concave mold can adopt the mosaic structure or not quenching. The structure of the non-quenched concave die is to stamp complex parts and improve the accuracy of stamping parts. At present, polyurethane rubber dies are commonly used to stamp soft and thin materials below 1 mm. Thin parts can also be stamped with large gaps. The concave mold is made with rounded corners, and the convex mold is made with sharp cutting edges. After the pressing plate is pressed against the sheet under the strong force of the spring, the material is pulled down by the sharp edge of the punch, and the size of the workpiece is generally the same as that of the punch. (2) The characteristics of thick plate stamping are as follows: 1) Thick plate stamping, the gap used by the die is large. 2) The thicker the material, the greater the punching deformation force and the greater the working stroke of the punch. When selecting a punch, care should be taken to make the required punching pressure less than the actual pressure that the punch can allow. Because the work hardening phenomenon is more obvious when the thick plate is stamped, the shear strength of the plate is slightly larger than that of the thin plate. When t/d>0.3, the shear strength of the thick plate is about 30% higher than that of the thin plate (t is the plate thickness, d is the diameter of the round stamping part or the side length of the square stamping part). The unloading force of thick material stamping is relatively large, and the rigid unloading device or air cushion is generally used to complete the unloading. 3) Using ordinary methods to stamp thick plates, the dimensional accuracy and section finish of stamping parts are relatively low (generally not higher than IT level and V3~V4). If you want to improve the quality, you can increase the refurbishment process or switch to precision stamping. 4) Due to the large deformation force of thick plate stamping, the method of reducing the punching force can be used for stamping. The method is: ① The convex and concave molds adopt the form of oblique blades. ②The step punch is used for multi-punch punching. ③The sheet material is heated and hot punching is used. ④ If the accuracy and section quality are not high, the gap can be increased appropriately. (3) Punching small holes on thick plates When punching small holes on thick plates (d≤t), if a mold with a general structure is used, the punch will easily break due to bending. In order to prevent the convex mold from bending when it is stressed, it can be slid and fitted on the outside of the convex mold to guide the sheath. The punch is protected by the guide sheath during work, so it will not bend or break. A guide plate can also be added to the stamping die to protect the punch with the guide plate, and the punch will not be easily broken. Previous post: What is the stamping performance of metal materials?