What are the application of separation process and forming process in automobile stamping parts?

2020-09-22 11:06:41

The stamping process can be divided into separation process and forming process (including bending, drawing and forming). The separation process is to separate the stamping part and the blank along a certain contour line in the stamping process, and the quality of the separated section of the stamping part must meet certain requirements; the forming process is to make the stamping blank plastic deformation under the condition of no damage, and transform it into the required finished product shape, and also meet the requirements of dimensional tolerance and other aspects.

According to the stamping temperature, there are cold stamping and hot stamping. This depends on the strength, plasticity, thickness, deformation degree and equipment capacity of the material, and the original heat treatment state and final service condition of the material should be considered.

1. Cold stamping metal processing at room temperature, generally applicable to the thickness of less than 4mm blank. It has the advantages of no heating, no oxide skin, good surface quality, convenient operation and low cost. The disadvantage is that there is work hardening phenomenon, which makes the metal lose further deformation ability. Cold stamping requires that the thickness of the blank is uniform and the fluctuation range is small, and the surface is smooth, without spots and scratches.

2. Hot stamping the metal is heated to a certain temperature range. The advantages are that the internal stress can be eliminated, the work hardening of automobile stamping parts can be avoided, the plasticity of materials can be increased, the deformation resistance can be reduced, and the power consumption of equipment can be reduced.

Die structure: die is a tool to separate or deform sheet metal. It is composed of upper module and lower module. The handle of the upper die is fixed on the slide of the press and moves up and down with the slider, while the lower die is fixed on the working table of the press.

The punch and die are the parts of the die that deform or separate the blank. They are fixed on the upper template and the lower template respectively by pressing plate. The upper and lower templates are respectively equipped with guide sleeve and guide pillar to guide the alignment of punch and die. The guide plate and positioning pin are used to control the feeding direction and length of the blank respectively. The function of the discharge plate is to make the workpiece or blank out of the punch after stamping.

2. Classification of die

Die is an essential die in stamping production. There are three kinds of stamping dies: simple die, continuous die and compound die.

(1) Simple die simple die is a kind of die which only completes one process in one stroke of the press. When working, the strip is fed along the two guide plates 9 on the female die until it touches the positioning pin 10. When the punch is pressed downward, the parts (or scrap) are pushed down into the die hole, and the strip clamps the punch and moves upward along with the punch. When the strip touches the discharge plate 8 (fixed on the die), it is pushed down so that the strip continues to feed between the guides. Repeat the above action and punch down the two parts.

(2) In one stroke of continuous die press, the die which completes several stamping processes at different parts of the die at the same time is called continuous die. When working, the positioning pin 2 is aligned with the pre punched positioning hole, the upper die moves downward, the punch 1 is blanking, and the punch 4 is punching. When the upper die returns, the discharge plate 6 pushes the scrap from the punch. At this time, the blank 7 is sent forward to perform secondary blanking. In this way, the feeding distance is controlled by the stopper pin.

(3) Compound die in a stroke, in the same part of the die at the same time to complete several stamping processes of the die, automotive parts known as composite die. The main feature of the compound die is that there is a punch and die 1 in the die. The outer circle of the punch is the cutting edge of blanking punch, and the inner hole is the drawing die. When the slider moves downward with the punch, the strip is first blanking in the punch 1 and blanking die 4. The blanking part is held by the drawing punch 2 in the lower die. When the sliding block continues to move downward, the die moves downward to draw. The ejector 5 and the stripper 3 push the drawing piece 9 out of the die in the return stroke of the slider. Compound die is suitable for stamping parts with large output and high precision.

3. Basic stamping process the main basic processes of stamping are blanking, punching, bending and drawing.

(1) Blanking and punching blanking and punching are the processes to separate the blank.

Blanking and punching process is exactly the same, but the purpose is different. When blanking, the separated part is the finished product, and the remaining periphery is the waste; punching is to obtain the hole, the punched sheet is the finished product, and the separated part is the waste. Blanking and punching are collectively referred to as blanking. The punch and die of the blanking die have sharp edges, and there is a gap of 5% - 10% of the plate thickness between the punch and the die, so as to ensure that the incision is neat and less burr.

(2) Bending is to make the workpiece to obtain various bending angles of different shapes. The working part of the bending die that makes the workpiece bend should have a proper fillet radius r, so as to avoid cracking when the workpiece is bent.

(3) Deep drawing: drawing is the process of making plate blank into cup or box. The punch and die edge of the drawing die should be rounded to avoid the workpiece being cracked. The gap between the punch and the die is slightly larger than the sheet thickness (generally 1.1-1.2 times of the plate thickness), so as to reduce friction. In order to prevent wrinkles, the edge of the blank should be pressed with a pressing plate (blank holder ring).