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Main Characteristics, Design And Manufacture Of Stamping Parts And Handling Of Common Problems
- Dec 21, 2018 -

Stamping parts are mainly metal or non-metal sheet metal, with the help of press pressure, through the stamping die stamping forming, it has the following characteristics:

The stamping is in the premise of material consumption is little, manufactured by stamping parts, light weight, good stiffness, and sheet after plastic deformation, improve the internal organizational structure of metal stamping parts, the intensity increased.

(2) The stamping parts have high dimensional accuracy, uniform size with the die, and good interchangeability. General assembly and use requirements can be met without further mechanical processing.

_During the stamping process, because the surface of the material is not destroyed, the stamping parts have better surface quality and smooth and beautiful appearance, which provides convenient conditions for surface painting, electroplating, phosphating and other surface treatment.

Design principles

(1) The stamping parts designed must meet the requirements of product usage and technical performance, and can be easily assembled and repaired.

(2) The stamping parts designed must be conducive to improving the utilization rate of metal materials, reducing the variety and specifications of materials, and reducing the consumption of materials as much as possible. In the case of permissible use of low-cost materials, as far as possible to make parts without waste and less waste blanking.

(3) The stamping parts designed must be simple in shape and reasonable in structure, so as to simplify the die structure and the number of working procedures, that is, to complete the whole part processing with the least and simplest stamping process, reduce the re-processing by other methods, and be conducive to stamping operation, facilitate the organization of mechanized and automated production, and improve labor productivity.

_The stamping parts designed in this paper, in order to ensure the normal use of the stamping parts, try to make the size accuracy and surface roughness level requirements lower, and is conducive to product interchange, reduce waste products and ensure product quality stability.

(5) The stamping parts designed should be conducive to the use of existing equipment, process equipment and process flow as far as possible, and to the extension of the service life of the die.

Handling of Frequent Questions

1. Adhesion and scratch: bad appearance on the surface of parts or dies due to friction between materials and punches or dies;

2. Burr: It mainly occurs in the shearing die and blanking die. The gap between the edges will produce burr in large or small hours.

3. Line offset: When the part is formed, the part contacted with the die is first extruded and a line is formed.

4. Convex and concave: foreign bodies (iron scraps, rubber, dust) mixed in the uncoiling line cause convex and concave;

5. Torture: due to uneven stress, poor matching of drawing ribs or poor control of press slider, the bending and strain occur at the R angle or embossing part of the workpiece.

6. Wrinkle: Wrinkle on edge or r part is caused by bad adjustment of slide block, low precision of press, improper adjustment of air cushion pressure, large punch or R part, etc.

7. Other specific problems: In daily production, there will be large or small punch size (which may exceed specifications) and large difference with punch size. In addition to considering the design size of forming convex and concave die, processing accuracy and blanking clearance, the following aspects should be considered to solve.

(1) When the cutting edge is worn, the tensile stress of the material increases, and the tendency of turning over and twisting of the stamping parts increases.  The size of punch will be smaller when turning material is produced.

(2) The high pressure on the material causes the plastic deformation of the material, which will lead to the larger punching size. When the pressure is reduced, the punching size will become smaller.

(3) The shape of the end of the punch edge. If the end is repaired with inclined or arc, the punch is not easy to turn over and twist due to the reduction of punching force, so the punch size will become larger. When the end of the punch is flat (without inclined or arc), the punch size tends to be smaller.

8. The method of restraining turning over and twisting of stamping parts

(1) Reasonable die design. In progressive die, the arrangement of blanking sequence may affect the forming accuracy of stamping parts. For the blanking of small parts of stamping parts, the blanking of larger area is usually arranged first, and then the blanking of smaller area is arranged to reduce the impact of blanking force on the forming of stamping parts.

(2) Pressure material. To overcome the traditional die design structure, a clearance is opened on the unloading plate (i.e. when the die is closed, the material can be compressed). In the key forming part, the unloading plate must be made into an inlay structure to facilitate the solution of the grinding (pressing) loss caused by the long stamping of the unloading plate pressing part, but the material can not be compacted.

(3) Adding pressure function. That is, to increase the dimension of the pressing part of the unloading insert (normal unloading insert thickness H+0.03mm), so as to increase the pressure on the side material of the die, thereby restraining the overturning and distortion of the stamping part during punching.

(4) The end of the punch edge is trimmed with an oblique or arc. This is an effective way to reduce cushioning cuts. By reducing the buffer cutting force, the tensile force on the side of the die can be reduced, and the effect of turning over and twisting of the stamping parts can be restrained.

(5) In daily die production, attention should be paid to maintaining the sharpness of punching convex and concave die edges. When the cutting edge is worn out, the tensile stress of the material will increase, and the tendency of turning over and twisting will increase.

(7) The unreasonable blanking clearance or uneven clearance are also the causes of turning over and distortion of stamping parts, which need to be overcome.