Stretching(also known as stretching, drawing) is a common process in the stamping process because it is suitable for all walks of life and has a wide range of practicality. From rough to tensile molding, multiple steps are required to complete, initial stretching → secondary stretching →. .. .. → Forming.
First, the concept of stretching:
1. Stretching: Press the board into a hollow piece(wall thickness is basically unchanged).
2. Stretching process: The material on the plane(flange) is transferred to the cylindrical(box) side wall, so that the shape of the plane changes greatly.
3. Stretch coefficient: the ratio of the tensile diameter to the diameter of the hair embryo "M"(the degree of deformation of the hair embryo to the workpiece).
Second, stretching process arrangements:
1. Parts with a thinner tensile depth than a larger diameter of the material: The method of increasing the height by reducing the cylindrical diameter can be reduced step by step.
2. Parts with similar tensile depth and diameter of the material: The radius of the circle can be reduced during the process of gradually reducing the cylindrical diameter.
3. The flange is large and the radius of the circle is very small: it should be achieved by multiple plastic surgery.
4. When the flange is too large: If necessary, take the form of expansion.
In order to reflect the principle of "flange invariance", the flange formed by the first stretching does not participate in the subsequent tensile deformation. The width flange tensile subtraction of the first concave die material(that is, the material forming the wall and bottom) should be 3 to 10 % more than the material actually required for the final stretching.
Note: Take the upper limit when calculating the number of stretches by area, instead take the lower limit. These excess materials will be returned to the flange in subsequent stretching steps, causing the flange to thicken but avoiding head cracking, and the area where the partial thinning can be corrected by shaping. Therefore, it is very important to strictly control the tensile height of each stretch.
Die design process:
After the client supplied the drawings,
Drawings assessment
One. Confirmation of processing process
Two. offer
Three. Draw die diagram
Four. Drawings
Five. Mold Materials, Mold Accessories
6. Mold processing spare material
Seven. heat treatment
Eight. Grinder Grinding, Wire Cutting Processing
Nine. assembling
10. Testing
11. Filing(Fahrenheit)