Stamping mold is a special process equipment used in cold stamping to process materials (metal or non-metal) into parts (or semi-finished products). The mold installed on the press is used to apply pressure to the material, causing it to separate or deform plastic, thus obtaining the required parts as a pressure processing method.
According to the process properties, stamping molds can be divided into: (1) stretching molds. It is a mold used to make open hollow parts from blank sheets, or to further change the shape and size of the hollow parts. (2) Trimming die. A mold that separates materials along a closed or open contour line. Such as trimming molds, punching molds, cutting molds, cutting molds, and blanking molds. (3) Forming mold. It is a mold that directly replicates and forms rough or semi-finished workpieces in the shape of convex or concave molds, while the material itself only produces local plastic deformation. Such as bulging molds, necking molds, expanding molds, undulating forming molds, and shaping molds. (4) Flanging mold. A mold that causes bending deformation of blank or other blanks along a straight line (flange line) to obtain a workpiece with a certain angle and shape.
1、 Structure and principle of trimming die
Trimming dies are molds used to cut off the supplementary parts of the drawing process and the excess parts of the pressing surface. According to the movement direction of the trimming insert, they can be divided into three categories: vertical trimming dies, wedge trimming dies, and vertical wedge trimming dies. On the premise of ensuring uniform release of shear stress in the workpiece, fully consider the reasonable arrangement of shear stress, lateral force, and impact force on the process of designing the mold. The workflow is as follows: lock the upper mold onto the upper slider of the machine tool, fasten the lower mold onto the workbench of the machine tool, place the stretched parts onto the lower mold of the mold, and set reasonable mold stamping parameters and stamping times. The upper mold mechanism moves downwards. As the slider moves downwards, the pressing core first presses the workpiece, and the lower slider continues to move downwards until the interaction between the upper and lower mold edges, punch, and concave mold sleeve separates the workpiece. The separated waste and beans slide down the set slide (slide plate) to the bottom of the workbench. At the same time, the slider on the machine tool returns to the top dead center, and the punching process completes a complete process. Due to the unavoidable impact force during punching, in order to reduce the impact force and extend the service life of the mold, polyurethane buffer blocks are added at the four corners of the lower mold. The strength of the mold itself is also important, so there are corresponding design requirements for each wall and reinforcing rib.
2、 Process Design of Trimming Mold
The rationality of the process design of the trimming mold directly affects the quality of the stamping parts and the lifespan of the mold. Good process design saves debugging time and the straight-through rate of the parts, greatly improving the efficiency of automated production.
1. Design of extreme operations for edge trimming and punching
Stamped parts have different shapes, and the trimming line (punching) on the surface often forms a certain value with the bottom surface of the mold. When the angle is greater than a certain angle, to ensure the lifespan of the mold and the quality of the workpiece, a wedge mechanism is designed for trimming (punching). Design basis: usually obtuse angle, acute angle ≤ 20., But in the process, it exceeds 20. Make the cutting surface into a plane, and at this point, the subsequent sequence must undergo further trimming operations.
2. Design of trimming and punching clearance
The punching gap is the fundamental guarantee for high-quality parts, and it varies with different materials and thicknesses. With the increase of material hardness and thickness, the punching gap needs to be increased to varying degrees. In addition, it is necessary to cooperate with a reasonable stamping frequency and regular maintenance of the mold, which are essential factors for stamping high-quality parts. Experience summary shows that the best punching clearance is to cut the section l, 3, and 2/3, respectively. At this time, it can not only ensure the absence of burrs, but also ensure the use of the cutting edge and reduce maintenance cycles.
3. Separation and cutting process
This type of process first separates the waste and then cuts it off. Mainly used for large exterior panels such as front and rear door outer panels, top cover outer panels, and machine cover outer panels. The advantages of this type of process are: reducing the generation of material slag in the trimming process, and preventing the trimming material slag from being carried to the subsequent cutting parts. The general process is that the waste knife is 3-5mm below the separation trimming line, and it is tightly attached to the trimming surface inside. Or make a height difference of about 3mm at the joint of the trimming knife block. The separation process should comprehensively consider the mold structure and size, and pay attention to referring to the machine tool process parameters.