Briefly introduce: the stamping process of automobile parts

The stamping process of automobile parts is a cold working process for obtaining various stamping parts such as automobile body, chassis and interior decoration by separating, forming, bending and drawing metal plates (mainly cold-rolled steel plates, galvanized steel plates, aluminum alloy plates, etc.) on a press. It is also one of the core processes for mass production of automobile parts. It has the characteristics of high efficiency, stable precision and low cost, and is suitable for mass production. The core is divided into two categories: separation process and forming process.

First, the core processing procedures (two categories, covering all automobile stamping parts forming needs)

1. Separation process: the plate is "cut/punched" according to the size, and only the shape is changed without plastic deformation.

The core is to ensure that the incision is smooth and burr-free, which is the basic process before stamping. There are two kinds of auto parts commonly used:

Blanking: the whole blank of stamping parts (such as the blank of door outer panel and fender) is punched out from the plate, and the waste is the surplus material, and the finished product is the required blank;

Punching: Punching holes/slots (such as bolt holes and installation slots) on the blank/finished product. The finished product is a workpiece with holes, and the waste is the punched core.

Supplement: Trimming and cutting are also separation processes, which are used to subsequently correct the edge size of stamping parts and split the conjoined blank.

2. Forming process: apply pressure to the plate to make it plastically deform, change its shape/size, and there is no material separation.

It is the core process of complex stamping parts of automobiles (such as body panels and chassis supports). There are four core types of automobile parts:

Bending: bending the plate into a specified angle/profile (such as the bending position of the door frame and frame longitudinal beam, the angle accuracy directly affects the assembly);

Deep drawing: the flat blank is drawn into an open hollow part (the core process of automobile panel, such as door outer panel, hood, trunk lid, fuel tank, etc.), and the stretching rate of the plate should be controlled to prevent cracking/wrinkling;

Flanging: at the hole/edge of stamping parts, the plate is bent into an upright edge (such as the flanging of the installation hole and the flanging of the door edge) to improve the installation strength and fit;

Pressing/stamping: Pressing the reinforcing ribs/marks (such as the reinforcing ribs of the car body floor and the model stamping of the parts) on the surface of the plate, the core function is to improve the rigidity and strength of the stamping parts and avoid deformation during driving.

Second, the standard process flow of automobile stamping parts (general for mass production, from raw materials to finished products)

The stamping of automobile parts is a mass production line, with a fixed and highly automated process, and a single process is matched with a special mold. The core process is: raw material blanking (uncoiling and leveling) → blanking/punching (blank making) → forming (bending/drawing/flanging/rib pressing, single pass/multi pass) → trimming/punching (finishing size) → flanging/shaping (fine shaping to ensure assembly).

Key links: uncoiling and leveling (unrolling and straightening the coil to ensure the flatness of the plate and avoid the deformation of the blank), shaping (the last forming process to correct the springback deformation of the stamping parts to ensure the accuracy and assembly consistency);

Core features: if the structure of a single stamping part is complex (such as a car door), it needs to be completed through multiple stamping processes, and each process corresponds to a set of special dies, which are the core of the precision and quality of stamping parts.

Third, the core supporting requirements of automobile stamping (different from ordinary stamping, adapting to the high requirements of automobile parts)

Raw materials: mainly cold-rolled low-carbon steel plate (body panel), galvanized plate/aluminized zinc plate (chassis with high rust prevention requirements) and aluminum alloy plate (lightweight body panel), and the plates should have good plasticity and stamping performance, and meet the requirements of stretching/bending without deformation and cracking;

Die: made of high-strength alloy die steel, the precision requirement is ≤0.05mm, and the surface is polished to ensure that the surface of stamping parts is smooth (no scratches or scratches). Die is the core cost item of automobile stamping, and a set of die for covering parts can reach millions;

Equipment: mechanical press/hydraulic press for mass production (tonnage from several hundred tons to several thousand tons, covering parts need large tonnage), fully automatic feeding and taking devices, and the efficiency can reach dozens or even hundreds of pieces per minute;

Quality Core: Strictly control three major problems (core defects of automobile parts), which are solved by optimizing die design, adjusting stamping pressure/speed and controlling sheet elongation.

Four, the typical application of automobile stamping

Almost all automobile metal parts are made by stamping process, and the core applications are:

Body covering parts: door, hood, trunk lid, fender, roof and body floor;

Chassis parts: frame longitudinal beam/cross beam, suspension bracket and brake bottom plate;

Small parts/interior parts: seat bracket, instrument panel skeleton, door hinge, various mounting brackets.