Stamping is a leading process in the automobile manufacturing process. The automobile stamping workshop is responsible for the storage of raw material coils and sheets; the uncoiling and shearing of coils; the shearing of sheets; the stamping production of large, medium and small stamping parts of various models; the storage of stamping parts; waste treatment and equipment, molds daily repair and maintenance tasks.
1. Process flow of stamping workshop
Raw materials (sheet and coil) storage→uncoiling line→cleaning and oiling of large pieces, uncoiling and shearing of small pieces→stamping production line→installation of molds and debugging of the first piece qualified→putting into mass production→rust prevention of qualified pieces→storage
2. The concept and characteristics of cold stamping
1. Cold stamping refers to a pressure processing method that uses a die installed on a press to apply pressure to the material at room temperature to cause separation or plastic deformation to obtain the required parts.
2. Features of cold stamping: stable product size, high precision, light weight, good rigidity, good interchangeability, high efficiency and low consumption, simple operation and easy automation.
Three, the classification of the basic process of cold stamping
Cold stamping can be summarized into two categories: forming process and separation process.
1. The forming process is to obtain a stamping part of a certain shape and size by plastically deforming the blank without breaking.
The forming process is divided into: drawing, bending, flanging, shaping, etc.
Drawing: A stamping process that uses a drawing die to turn a flat blank (process piece) into an open hollow piece.
Bending: A stamping method that bends sheets, profiles, pipes or bars into a certain angle and curvature to form a certain shape.
Flanging: It is a stamping forming method that turns the sheet material into a vertical edge along a certain curvature on the flat part or curved part of the blank.
2. The separation process is to separate the sheet metal according to a certain contour line to obtain a stamped part with a certain shape, size and cut surface quality.
The separation process is divided into: blanking, punching, corner cutting, trimming, etc.
Blanking: The materials are separated from each other along the closed curve, and when the part inside the closed curve is used as a blanking part, it is called blanking.
Punching: The material is separated from each other along the closed curve, and when the part outside the closed curve is used as a punching part, it is called punching.
4. The name and code of each process
Among the parts produced in the stamping shop, some belong to the cover parts, such as: engine hood outer panel, roof cover, car door and so on.
5. Requirements for covering parts
1. The size and shape should conform to the inspection fixture and the sample that has been welded and matched.
2. Good surface quality. Defects such as ripples, wrinkles, dents, scratches, abrasions, and indentations are not allowed on the surface of the outer cover (especially the outer cover of a car). The ridges should be clear and straight, and the curved surfaces should be smooth and evenly transitioned.
3. Good rigidity. During the forming process of the covering part, the material should have sufficient plastic deformation to ensure that the part has sufficient rigidity.
4. Good craftsmanship. The cover part should have good stamping process performance and welding process performance to reduce the production cost of stamping and welding. The stamping process mainly depends on whether the various processes, especially the drawing process can be carried out smoothly and whether the production can be stabilized.
Six, the composition of the general mold
1. Working parts
Including parts such as punch and die.
2. Position the part
It mainly includes retaining pins, positioning pins, side blades and other parts.
3. Pressing, unloading and jacking parts
It mainly includes unloading plate, ejector, pneumatic ejector and other parts
4. Guide parts
Including guide post, guide sleeve, guide plate and other parts.
5. Support parts
It includes parts such as upper and lower templates and punch and concave die fixing plates.
6. Fastening parts
Including hexagon socket screws, discharge screws and other parts.
7. Buffer parts
Including unloading spring, polyurethane rubber and nitrogen cylinder, etc.
8. Safety parts and other auxiliary parts
There are mainly safety side pins, safety screws, work limiters, storage limiters, loading and unloading racks, waste chutes, lifting rods, lifting lugs, etc.
Safety side pin: the main function is to prevent the fastening screws of the upper mold pressing plate from loosening or breaking, causing the pressing plate to fall, resulting in heavy losses of personnel and tooling.
Storage limiter: the main function is to prevent the elastic components of the mold from being under pressure for a long time and to prevent the long-term contact of the cutting edge from affecting the life of the cutting edge. (Usually polyurethane rubber)
Work limiter: the main function is to limit the depth of the punch and die.
7. Factors affecting mold life
1. The impact of stamping process and die design and measures to improve the life of the die.
(1) Influence of raw materials for cold stamping
For example: raw material thickness tolerance does not meet the requirements, material performance fluctuations, poor surface quality and unclean, etc.
A. Strict inspection should be carried out on the grade, thickness and surface quality of raw materials before stamping
B. Ensure material surface quality and cleanliness
(2) The influence of layout and edge
The layout method and overlap value have a great influence on the life of the mold. Unnecessary reciprocating feeding layout method and too small overlap value are often the important reasons for the rapid wear of the mold and the damage of the punch and concave die.
(3) Influence of mold guiding structure and guiding precision
Necessary and reliable guidance is extremely effective in reducing the wear of working parts and avoiding damage to the convex and concave dies.
(4) Influence of mold geometric parameters
2. The shape, gap and fillet radius of the punch and die not only have a great influence on the forming of stamping parts, but also have a great influence on the wear of the die.
(1) Influence of the material of the mold
The influence of the material properties of the mold and the quality of heat treatment on the life of the mold is the most important factor among the factors affecting the life of the mold.
(2) Influence of thermal processing and surface strengthening of the mold
(3) Influence of mold processing technology
After the mold is processed, the surface roughness of the mold has a great influence on the life of the mold, so the processing technology should be selected reasonably according to the condition of the workpiece.
(4) The influence of the precision and rigidity of the press
(5) The influence of the use, maintenance and maintenance of the mold
Proper use, maintenance and storage of molds are important aspects to improve mold life. It includes the correct installation and adjustment of the mold; pay attention to keep the mold clean and reasonable lubrication; prevent misfeeding and double feeding; strictly control the depth of the punch entering the concave mold, and control the bottom dead center position of the upper mold in the process of correcting bending and shaping. ; Timely grinding, polishing, etc.
