Stamping technology

The precision and structure of the mold directly affects the forming and precision of the stamping. Mold manufacturing cost and life are important factors affecting the cost and quality of stamping parts. Mold design and manufacturing require more time, which extends the production lead time for new stampings. Stamping Pressing a press and a die to apply an external force to a sheet, a strip, a pipe, a profile, etc., to cause plastic deformation or separation, thereby obtaining a forming process of a workpiece (stamping part) of a desired shape and size. Stamping and forging are the same plastic processing (or pressure processing), collectively called forging. The stamped blanks are mainly hot rolled and cold rolled steel sheets and strips. Of the world's steel, 60 to 70% are sheets, most of which are stamped into finished products. The body, chassis, fuel tank, radiator plate of the automobile, the steam drum of the boiler, the casing of the container, the iron core silicon steel sheet of the motor and the electric appliance are all stamped and processed. There are also a large number of stamping parts in instruments, household appliances, bicycles, office machinery, living utensils and other products.
Advantage of stamping

Compared to other methods of machining and plastic working, stamping has many unique advantages both technically and economically. The main performance is as follows.

(1) The stamping process has high production efficiency and is easy to operate, and is easy to mechanize and automate. This is because the stamping relies on die and stamping equipment to complete the processing. The number of strokes of ordinary presses can reach dozens of times per minute, and the high-speed pressure can reach hundreds or even thousands of times per minute, and each press stroke is May get a punch.

(2) Since the die ensures the size and shape accuracy of the stamping part during stamping, and generally does not damage the surface quality of the stamping part, and the life of the die is generally long, the quality of the stamping is stable, the interchangeability is good, and it has “the same”. Characteristics.

(3) Stamping can process parts with large size and complex shapes, such as stopwatches as small as watches, as large as car longitudinal beams, covering parts, etc., plus cold deformation hardening effect of materials during stamping, strength of stamping and The stiffness is high.

(4) Stamping generally has no chip scraps, less material consumption, and no need for other heating equipment. Therefore, it is a material-saving and energy-saving processing method, and the cost of stamping parts is low.

Due to the superiority of stamping, stamping processing is widely used in various fields of the national economy. For example, in the aerospace, aviation, military, machinery, agricultural machinery, electronics, information, railway, post and telecommunications, transportation, chemical, medical equipment, household appliances and light industry departments have stamping processing. Not only is it used by the entire industry, but everyone is directly linked to stamping products. There are many large, medium and small stamping parts on airplanes, trains, cars and tractors. The body, frame and rim of the car are stamped and processed. According to relevant survey statistics, 80% of bicycles, sewing machines and watches are stamped parts; 90% of TV sets, tape recorders and cameras are stamped parts; there are food metal cans, steel-fired boilers, enamel bowls and stainless steels. =_blank>Stainless steel cutlery, all of which are stamped and processed products using molds; even the hardware of the computer is not missing.

However, the molds used in the stamping process are generally specialized, and sometimes a complex part requires several sets of molds to be formed, and the mold manufacturing has high precision and high technical requirements, and is a technology-intensive product. Therefore, only in the case of large batch production of stamping parts, the advantages of stamping processing can be fully reflected, thus obtaining better economic benefits.
Problems and disadvantages

Of course, there are some problems and shortcomings in stamping. Mainly manifested in the noise and vibration generated during stamping processing, and the operator's safety accidents occur. However, these problems are not entirely due to the stamping process and the mold itself, but mainly due to the traditional stamping equipment and backward manual operations. With the advancement of science and technology, especially the development of computer technology, with the advancement of electromechanical "target=_blank> mechatronics technology, these problems will be solved as soon as possible and perfect.
Stamping features Compared with castings and forgings, stamping parts are thin, uniform, light and strong. Stamping can produce workpieces with ribs, ribs, undulations or flanging that are difficult to manufacture by other methods to increase their rigidity. Thanks to the use of precision molds, the precision of the workpiece can reach micron level, and the repeatability is high and the specifications are the same, and the holes, bosses and the like can be punched out. Cold stampings are generally no longer machined or require only a small amount of machining. The precision and surface condition of hot stampings are lower than that of cold stampings, but they are still superior to castings and forgings, and the amount of cutting is small.

Stamping is an efficient production method. It adopts composite molds, especially multi-station progressive molds. It can complete multiple stamping processes on one press (single or multi-station) to realize unwinding and rectification of strips. Flat and punched into fully automatic production of forming and finishing. High production efficiency, good working conditions, low production costs, and generally can produce hundreds of pieces per minute.
Stamping and stamping are mainly classified according to the process, and can be divided into two categories: separation process and forming process. The separation process is also called punching, and its purpose is to separate the stampings from the sheet along a certain contour line, while ensuring the quality requirements of the separated sections. The purpose of the forming process is to plastically deform the sheet without breaking the blank to produce a workpiece of the desired shape and size. In actual production, it is often the case that multiple processes are integrated into one workpiece. Blanking, bending, shearing, drawing, bulging, spinning, and correction are several major stamping processes.
The surface and intrinsic properties of the stamping material sheeting have a great influence on the quality of the stamped product. The requirements for stamping materials are:

1 The thickness is accurate and uniform. The stamping die is precise, the gap is small, the thickness of the sheet is too large to increase the deformation force, and the jamming material is caused, and even the die is cracked; if the sheet material is too thin, the quality of the finished product is affected, and even the crack occurs even when the drawing is deep.

2 The surface is smooth, no spots, no flaws, no scratches, no surface cracks, etc. All surface defects will remain on the surface of the finished workpiece, and the crack defects may be deepened and expanded in the process of bending, deep drawing, forming, etc., resulting in waste.

3 The yield strength is uniform and there is no obvious directionality. Anisotropy (see the plastic deformation of the sheet in the drawing process of drawing, flanging, bulging, etc., due to the occurrence of the direction of the yield, the amount of plastic deformation is inconsistent, will cause uneven deformation, resulting in inaccurate forming Defective or scrap.

4 Uniform elongation is high. In the tensile test, the elongation before the sample begins to appear in the necking phenomenon is called uniform elongation. When drawing, the deformation of any area of the sheet should not exceed the uniform extension of the material, otherwise uneven deformation will occur.

5 The yield ratio is low. The ratio of the yield limit to the strength limit of a material is called the yield ratio. The low yield ratio not only reduces the deformation resistance, but also reduces the tendency to wrinkle during drawing, reduces the amount of springback after bending, and improves the accuracy of the bending piece.

6 Low work hardening. The work hardening which occurs after cold deformation increases the deformation resistance of the material and makes it difficult to continue deformation. Therefore, a plate with a low hardening index is generally used. However, the material with high hardening index has good plastic deformation stability (that is, plastic deformation is relatively uniform), and local cracking is not easy to occur.

In actual production, the process test similar to the stamping process, such as the drawing performance test and the bulging performance test, is used to test the punching performance of the material to ensure the quality of the finished product and high qualification rate.
The precision and structure of the stamping die directly affect the forming and precision of the stamping. Mold manufacturing cost and life are important factors affecting the cost and quality of stamping parts. Mold design and manufacturing require more time, which extends the production lead time for new stampings. Standardization of mold bases, formwork, guides and development of simple molds (for small batch production), composite molds, multi-station progressive molds (for mass production), and the development of rapid mold change devices to reduce the workload of stamping production preparation And shortening the preparation time, the advanced stamping technology suitable for mass production can be reasonably applied to small batch and multi-variety production.
Stamping equipment

In addition to the formation of thick plate hydraulic presses, mechanical presses are generally used. Centered on modern high-speed multi-station mechanical presses, equipped with unwinding, leveling, finished product collection, conveying and other machinery as well as mold libraries and rapid mold change devices, and using computer program control, can form a high-productivity automatic stamping production line.
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