The customer's requirements for materials are not very high. If repeated mold tests do not meet the requirements, you can try again with materials with good tensile properties. Good materials are half the battle. For stretching, this cannot be ignored. Cold-rolled steel plates for drawing mainly include 08Al, 08, 08F, 10, 15 and 20 steels. The largest is 08 steel, which is divided into boiling steel and killed steel. Boiling steel has low price and good surface quality. The segregation is serious, and there is a trend of "strain aging". Not suitable for parts that require high stamping performance and appearance. Killed steel is better, its performance is even, but its price is higher. The representative brand is aluminum killed steel 08Al, and the foreign steel adopts Japanese SPCC-SD deep drawing steel, which has better tensile properties than 08Al.

2. Smoothness of mold surface

During the deep drawing delay, there is not enough grinding on both sides of the die and the blank holder, especially when drawing stainless steel plates and aluminum plates, it is more likely to produce scars, which may lead to tensile fracture in severe cases.

3. Determination of blank size

It is our principle to wrinkle more and crack less. Blank positioning design must be correct. The diameter of the blank of a simple rotary drawing part will not be reduced. Although the thickness of the material has changed, it is basically the same as the original thickness, and the closure can be calculated according to the principle that the blank area is equal to the area of the drawing part (if trimming must be added). However, the shape and technology of drawing parts are often complicated, and sometimes thinning and drawing are needed. Although there are many 3D softwares that can calculate unfolded materials, their accuracy cannot meet the requirement of 100%.

Solution: Try the materials.

A product has to go through multiple processes, and the first process is generally a stamping process. First of all, we should calculate the expanding material, have a general understanding of the shape and size of the blank, and determine the overall size of the blanking die. The die and blanking process of the die are carried out after the die design is completed. First, the blank is machined by wire cutting (when the blank is large, it can be milled by a milling machine and then clamped). After repeated experiments in the subsequent drawing process, the size of the blank is finally determined, and then the punch and die of the blanking die are processed.

In the flip-chip process, the drawing die is tested first, and then the blanking edge size of the semi-finished blank is measured.

4. Tensile coefficient

Drawing coefficient is one of the main process parameters in drawing process calculation, which is usually used to determine the order and times of drawing.

There are many factors that affect the drawing coefficient m, including material properties, relative thickness of materials, drawing method (with or without blank holder), drawing times, drawing speed, punch radius, lubrication and so on.

In the process of die repair, it is not easy to adjust the relative thickness of materials, drawing method (whether there is blank holder) and drawing times. You must be careful. You'd better check with your colleagues when choosing the stretching coefficient m.

5. Selection of processing oil for tungsten steel wire drawing die

The choice of processing oil is very important. The way to judge whether the lubricant is suitable is that when the product is taken out of the mold, if the temperature of the product is too high to be touched by hand, the choice of lubricant and lubrication method must be reconsidered, and lubricant should be coated on the cavity or a thin film bag should be placed on the sheet.

If there are tensile cracks, apply lubricant to the female die (without lubricant to the male die), and cover the workpiece with a plastic film of 0.0 13-0.0 18mm on the female die side.