Cracks in the corresponding part of the shoulder of the concave mold
Of course, it is bulging forming. When a small amount of material flows in, cracks occur in the RD department due to bending and straightening.
(1) The fillet radius of the concave mold is too small (rd). When bulging is the main deformation and there is a small amount of material flowing in, if the RD is too small, work hardening will occur due to bending and straightening, and cracks will often occur around the RD department. Firstly, it is necessary to grind the RD part carefully. If it still breaks, increase the RD appropriately.



(2) The adjustment of the edge pressing ring is not good. When the RD is small and the edge pressing force is too small, there are small wrinkles in the flange section, which often causes the RD department to rupture in the later stage of processing. Generally speaking, increasing the edge pressing force can solve the problem.



(3) Poor machining of concave die fillet radius (rd). If the radius of the concave die corner is not processed properly, the product will be scratched during deep drawing, and at the same time, cracks will occur at the radius of the concave die corner in the later stage of processing. The elimination method is to grind along the direction of material movement with a grinding wheel.



(4) The function of deep stretching is not good. If the shape of the deep drawing rib is not good and the edge pressing force is weak, as long as there is a small amount of material activity in the later stage of the process, it often breaks. If the shape of the deep drawing rib is not changed, it is necessary to increase the edge pressing force.



Straight edge wall rupture
When drawing a square cylinder, extensive deep drawing fractures occur around the center of the straight wall. See the figure below.



(1) Product appearance. ① Deepen and cross the river. If reducing the drawing depth is used to prevent cracking, the first step is to check for other reasons. When other factors have been eliminated but the cracking cannot be stopped, the final method is to reduce the drawing depth and add a finishing drawing process.



② The fillet radius (rd) of the concave mold is too small. The measure to prevent rebound and depression on the side wall of the straight edge during square tube deep drawing is generally to use the method of stretching the deep drawing rib, but this method has the defect of causing deep drawing rib scars. Therefore, when deep drawing is not used, the measure for stretching forming is to make the gap slightly smaller than the plate thickness, and at the same time, choose the drawing method when d is too small. If cracks occur beyond the tensile limit, the RD can be slightly increased before conducting a trial deep drawing.



(2) Stamping premise. ① Excessive edge pressure. The flange surface is all shiny, indicating that the edge pressure is too high, which can reduce the edge pressure to a level that allows the material to flow in without wrinkling.



② Poor lubrication of the concave mold surface. To make the material easily flow in, it is necessary to check the type and amount of lubricating oil.



(3) Mold question. ① Poor machining and fitting of the concave mold surface. When the product ruptures and there are scratches on the flange surface, it is necessary to use a grinding wheel to polish it well, achieving the premise of easy material inflow.



② The gap is too small. When the side wall of the product shines and cracks, it is because the thinning amount of the side wall is too large, so the gap needs to be adjusted.



③ The position and shape of the deep drawing ribs are poor. There are many cases of rupture due to excessive air force on the deep drawing tendon, so it is necessary to reduce the air force on the deep drawing tendon.



④ Poor mold accuracy. Poor mold accuracy with mold core offset; Poor parallelism and verticality between convex and concave molds. If the mold is checked in advance, no problems will occur during the trial drawing.



⑤ Insufficient rigidity of the edge pressing ring. When the rigidity of the edge pressing ring is insufficient, it will only be subjected to severe tension at a few slow impact pin positions, resulting in rupture.



⑥ The accuracy of the press is poor. When the accuracy of the press is poor, defects similar to poor mold accuracy will occur. Before trial drawing, the machine tool must be kept in a high-precision state and a trial drawing must be carried out.



(4) Materials. ① When defects arise due to insufficient tensile strength of the material and excessive grain size, it is necessary to change the material.



② When defects occur due to insufficient thickness of the board, it is necessary to increase the thickness of the board.




Reading source: Manufacturer of flat plate faucets www.baolonghs.com