Process design of trimming mold

Stamping mold is a special process equipment that processes materials (metal or non-metal) into parts (or semi-finished products) in cold stamping processing. Use the mold installed on the press to apply pressure to the material to cause separation or plastic deformation, thereby obtaining the required parts.

According to the process properties, stamping molds can be divided into: (1) tensile molds. It is a mold that makes the sheet blank into an open hollow piece, or further changes the shape and size of the hollow piece. (2) Trim the edge mold. A mold that causes the material to produce a separate mold along a closed or open contour line. Such as trimming die, punching die, cutting die, cutting die, blanking die, etc. (3) Forming die. It is a mold that directly replicates the blank or semi-finished workpiece according to the shape of the convex and concave molds, while the material itself only produces local plastic deformation. Such as expansion die, shrink die, flared die, undulating forming die and shaping die, etc. (4) Flip mold. The sheet blank or other blank is bent and deformed along a straight line (fringe line), thereby obtaining a mold of a workpiece of a certain angle and shape.

1. Structure and principle of edge trimming mold

The trimming mold is a mold used to cut off the process supplementary part of the drawing part and the excess part of the pressing surface. According to the movement direction of the trimming insert, it can be divided into three categories: vertical trimming mold, oblique wedge trimming mold and vertical oblique wedge trimming mold. On the premise of ensuring the uniform release of the shear stress of the mold, the shear stress, lateral force and impact force of the mold are fully considered to arrange the mold reasonably for its process. The workflow is: lock the upper mold on the machine tool slider, tighten the lower mold on the machine tool workbench, place the stretched part on the mold bottom mold, and set reasonable mold stamping parameters and stamping times. The upper mold mechanism moves downward. As the slider moves downward, the pressing core first presses the piece, and the lower slider continues to move downward until the upper and lower mold edges, punches and the die sleeve interact to separate the piece. The separated waste and material beans slide downward along the set slide (slide plate) to the workbench. At the same time, the slider on the machine tool returns to the upper dead point, and the complete process of the punching process is completed. Since punching cannot avoid impact force, in order to reduce impact force and extend the service life of the mold, polyurethane buffer blocks are added to the four corners of the mold under the mold. The strength of the mold itself is also very important, so there are corresponding design requirements for each wall and reinforcement.

2. Technology design of edge trimming mold

Whether the process design of the trimming mold is reasonable directly affects the quality of stamped parts and the life of the mold. Good process design saves debugging time and the direct-through rate of the parts, greatly improving the automation production efficiency.

1. Extreme work design for edge trimming and punching

The shapes of stamping parts are different, and the shape at the trimming line (punching) is often at a certain value with the bottom of the mold. When the angle is greater than a certain angle, it is necessary to design an inclined wedge mechanism to trim (punching) in order to ensure the life of the mold and the quality of the workpiece. Design benchmark: Usually obtuse angle, acute angle ≤20. , but more than 20 in the process. When the shearing surface is made into a plane, the subsequent sequence must be re-edited.

2. Design of trimming and punching gap

The punching gap is the basic guarantee for high-quality parts. Different materials and different material thicknesses have different punching gaps. As the material hardness increases and the thickness increases, the punching gap must be increased to varying degrees. In addition, it is necessary to cooperate with reasonable stamping frequency and regular maintenance of molds, which are essential factors for stamping high-quality parts. Experience summary shows that the cutting section l, 3 cut and 2/3 pull are the best cutting gaps. At this time, it can not only ensure the absence of burrs, but also ensure the use of the cutting edge and reduce the maintenance cycle.

3. Separation and cutting process

This kind of process separates the waste material first and then cuts it off. It is mainly used in front and rear door outer panels, top cover outer panels, machine cover outer panels and other large outer panels. The advantages of this type of process are: reducing the production of slag in the edge trimming process and preventing the slag from being brought to the subsequent cut parts. The general process is that the waste knife is 3 to 5mm lower than the separation edge trimming line, and the inside is close to the edge trimming surface. Or make a height difference of about 3mm at the splicing of the trimming knife block. The separation process should comprehensively consider the mold structure and size, and pay attention to the machine tool process parameters.

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