Product Details
Stretching mold professional mold manufacturer
Selected high-quality manufacturers for drawing die manufacturing
Drawing die introduction and process characteristics
Drawing (also known as drawing, deep drawing) is a common process in stamping technology because it is suitable for all walks of life and has wide practicability. From blank to stretch forming, it needs to be completed in multiple steps, primary stretching----secondary stretching----forming.The mold will have various problems during the stretching process. Common problems such as: wrinkling, top R cracking, product surface strain, stretching height is too high or too short, etc... A series of question. Therefore, the stretching process is also a difficult point in the stamping die.
The following Dongmo will introduce the general characteristics of the metal drawing die for you:
First, the concept of stretching:
1. Stretching: Press the sheet into a hollow part (the wall thickness is basically unchanged).
2. Stretching process: the material on the plane (flange) is transferred to the side wall of the cylinder (box), so the overall dimensions of the plane change greatly.
3. Stretching coefficient: the ratio of the drawing diameter to the blank diameter "m" (the degree of deformation from the blank to the workpiece).
Second, the main factors affecting the tensile coefficient:
1. Mechanical properties of materials (yielding strength - elastic deformation; tensile strength - plastic deformation; elongation coefficient; section shrinkage rate)
2. The relative thickness of the material.
3. Stretching times.
4. Stretching method.
5. Corner radius of convex and concave die.
6. Lashen working surface finish and lubrication conditions, clearance, etc.
7. Stretching speed.
Second, the main factors affecting the tensile coefficient:
1. Mechanical properties of materials (yielding strength - elastic deformation; tensile strength - plastic deformation; elongation coefficient; section shrinkage rate)
2. The relative thickness of the material.
3. Stretching times.
4. Stretching method.
5. Corner radius of convex and concave die.
6. Lashen working surface finish and lubrication conditions, clearance, etc.
7. Stretching speed
Third, the stretching process arrangement:
1. Parts with thinner material and larger drawing depth than diameter: the method of reducing the diameter of the cylinder to increase the height, and the radius of the fillet can be successively smaller.
2. Parts with thicker material and similar drawing depth and diameter: it can be used to reduce the fillet radius in the process of gradually reducing the cylindrical diameter while maintaining the same height.
3. The flange is large and the radius is small: it should be achieved by multiple shaping.
4. When the flange is too large: adopt the expansion method if necessary.
In order to reflect the principle of "flange unchanged", the flange formed by the first stretching does not participate in the subsequent stretching deformation, and the wide flange is stretched to reduce the material of the first die (that is, the material that forms the wall and the bottom). There should be 3-10% more material than is actually required to complete the final stretch.
Note: When the number of stretches is calculated by area, take the upper limit, otherwise take the lower limit. This excess material will gradually return to the flange in subsequent stretches, causing the flange to thicken but to avoid head cracking, and the localized thinning area can be corrected by shaping. Therefore, it is very important to strictly control the height of each stretch when stretching.
Fourth, box stretching
The corner part is equivalent to the stretching of the cylinder, and the straight wall part is equivalent to the bending deformation;
Fifth, stretch lubrication
During the stretching process, there is friction between the material and the die, so there must be a special stamping and stretching lubricating oil. Large friction will not only increase the tensile coefficient, but also increase the tensile force and wear and scratch the die and tool. The inter-surface is therefore detrimental, so lubrication conditions are necessary during stretching.
The above is a brief introduction and characteristics of Dongmo is a drawing die. Although some problems with the drawing die are indeed a headache, there are solutions to the problems. As long as the two points of "force" and "gap" are mastered, many problems can be solved easily.
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