Stamping is a leading process in the automotive manufacturing process. The automobile stamping workshop is responsible for the storage of raw material coils and sheets; the uncoiling and shearing of the coils; the cutting of sheet materials; the stamping production of large, medium and small stamping parts of various models; the storage of stamping parts; waste disposal and equipment, molds routine maintenance and maintenance tasks.

1. Process flow of stamping workshop

Raw materials (sheets and coils) warehousing → uncoiling line → cleaning and oiling of large pieces, uncoiling and shearing of small pieces → stamping production line → installation of molds and debugging, the first piece is qualified → put into mass production → rust prevention of qualified pieces → storage

2.the concept and characteristics of cold stamping

A. 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, thereby obtaining the required parts.

B. 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.

3. Classification of basic processes of cold stamping

Cold stamping can be divided into two categories: forming process and separation process.

A. The forming process is that the blank is plastically deformed without breaking to obtain a stamping part of a certain shape and size.

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 part) into an open hollow part.

Bending: A stamping method in which sheets, profiles, pipes or bars are bent into a certain angle and a certain curvature to form a certain shape.

Flanging: It is a stamping forming method in which the sheet is turned into a vertical edge along a certain curvature on the flat part or the curved part of the blank.

B. The separation process is to separate the sheet material according to a certain outline to obtain a stamping part with a certain shape, size and quality of the cut surface.

The separation process is divided into: blanking, punching, corner cutting, trimming, etc.

Blanking: When the materials are separated from each other along the closed curve, and the part within the closed curve is used as a blanking part, it is called blanking.

Punching: When the material is separated from each other along the closed curve, and the part outside the closed curve is used as a punching part, it is called punching.

4, Each process name and its code

Name of Process

Drawing

Trimming

Pierce

Restrike

Forming

Flanging

Separating

Blanking

Burring

Cam pierce

Code

DR

TR

PRC

RST

FO

FL

SEP

BL

BUR

CAM-PRC

Some of the parts produced in the stamping workshop belong to covers, such as: hood outer panels, top covers, doors, etc.

5. Requirements for auto body parts

A. The size and shape should be in accordance with the inspection tool and the matched sample after welding.

B. Good surface quality. The surface of the outer cover (especially the exterior auto part) is not allowed to have defects such as corrugations, wrinkles, dents, scratches, abrasions, indentations, etc. The ridges should be clear and straight, and the curved surfaces should be smooth and evenly transitioned.

C. Good rigidity. During the forming process of the auto body parts, the material should have sufficient plastic deformation to ensure that the part has sufficient rigidity.

D. Good craftsmanship. The exterior cover parts should have good stamping process performance and welding process performance to reduce the production cost of stamping and welding. Stamping manufacturability mainly depends on whether each process, especially the deep drawing process can be carried out smoothly and stable production.

6, the composition of the general mold

A. Working Parts

Including convex and concave dies and its spare parts.

B. Position the part

It mainly includes stopper pins, locating pins, side blades and other spare parts

C. Pressing, unloading, topping parts

It mainly includes parts such as discharge plate, ejector and pneumatic ejector.

D. Guide parts

Including guide posts, guide sleeves, guide plates and other parts.

E. Supporting Parts

Including parts such as upper and lower formwork and convex and concave die fixing plate.

F. Fastening parts

Including hexagon socket screws, unloading screws and others.

G. Cushioning parts

Including discharge spring, urethane rubber and nitrogen cylinder, etc.

H. 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 die 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 element 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 using polyurethane rubber)

Work limiter: The main function is to limit the penetration depth of the punch and die.

7, Factors affecting the life of the molds

7.1. 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 tolerances not meeting requirements, material properties fluctuating, poor surface quality and uncleanness, etc.

A. The grade, thickness and surface quality of raw materials should be strictly checked before stamping

B. Ensure material surface quality and cleanliness

(2) The influence of layout and edge overlap

The nesting method and the overlap value have a great influence on the life of the mold. The unnecessary reciprocating feeding nesting method and the too small overlap value are often the important reasons for the sharp wear of the mold and the gnawing of the convex and concave die.

(3) Influence of mold guide structure and guide accuracy

Necessary and reliable guidance is extremely effective in reducing the wear of the working parts and avoiding the gnawing of the convex and concave dies.

(4) Influence of die geometric parameters

7.2. The shape, clearance and fillet radius of the dies 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 heat treatment quality on the life of the mold is the most important factor affecting the life of the mold.

(2) The 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 reasonably selected according to the conditions of the parts.

(4) Influence of the accuracy and rigidity of the press

(5) The influence of the use, maintenance of the mold

Proper use, maintenance and storage of molds are important aspects of improving mold life. It includes the correct installation and adjustment of the mold; pay attention to keeping the mold clean and reasonably lubricated; prevent miss-feeding and double material feeding; strictly control the depth of the convex die entering the concave die, and control the correction of bending, shaping and other processes, as well as the position of the bottom end center of the upper die; timely grinding and polishing.