What factors will affect the tensile coefficient in the design of the drawing part processing mold
- Processing characteristics of wire drawing dies
1. Protruding, the gap between the concave molds should be uniformly produced. For a drawing die without a guide device, the same piece should be placed so that the punch can be adjusted and the position of the die is correct; for a guided drawing die, it is also necessary to ensure that the gap between the punches is uniform.
2. The material has good compactness and elastic deformation when stretched and deformed. Before the convex and concave dies are hardened, test punching and trimming should be carried out. It is easy to process and has good wear resistance. After the deep drawing test die is qualified, press The blanking die is manufactured in the state of the die trial.
3. For the drawing die without guiding equipment, it is required to place the same piece, adjust the punch, and the position of the die is correct; for the drawing die with guidance, it is necessary to ensure that the gap between the punches is uniform when assembling.
4. The processing of drawing dies is generally to make drawing dies first, and after passing the deep drawing test, make blanking dies according to the test conditions, the processability of die parts and the convenience of die maintenance, all of which should be considered in design. .
5. The processing quality of deep drawing dies has been paid more and more attention, so processing the drawing dies into parts is also an important factor to improve the quality of the dies.
2. Tensile mold characteristics
1. The concept of stretching.
(1) Stretching: Press the sheet into a hollow piece (almost no change).
(2) Stretching process: The material is transferred to the side wall of the cylinder (box) through a plane (flange), so that the overall dimensions of the plane will change significantly.
(3) Tensile coefficient: the ratio of the tensile diameter to the diameter of the blank (the degree of deformation from the blank to the workpiece).
2. Main influencing factors of tensile coefficient:
(1) Mechanical properties of the material (reduced strength – elastic deformation; tensile strength – plastic deformation; elongation coefficient; section shrinkage).
(2), relative material thickness.
(3), the number of stretches.
(4), stretching method.
(5), convex and concave die fillet radius.
(6) The drawing surface is clean, lubricated, clearance, etc.
(7), expansion rate.
3. Layout of stretching process
1. Parts whose drawing depth is less than the diameter: the height of the cylinder can be increased by reducing the diameter of the cylinder, so that the angular radius can be gradually reduced.
2. Material parts with equal thickness and diameter: The height can be kept constant to reduce the radius of the fillet, if it is to gradually reduce the diameter of the small cylinder.
3. The flange is large and the circle radius is extremely small: it should be obtained by multiple forming.
4. The flange is too large: if necessary, use the expansion molding method.
In order to reflect the principle of “unchanged convex edge”, the flange formed by one stretch does not participate in all subsequent stretching deformation, while the wide flange stretching reduces the material that first enters the die (that is, the material that forms the wall and the bottom). ) 3~10% more than the final stretched material.
Note: The number of upper bounds for multiple times is taken from the lower bounds of multiple times within the zone. The excess material will be returned to the flange in the subsequent multiple drawing steps, which will thicken the flange without pulling and can be repaired by reshaping. Therefore, each stretch height should be strictly controlled when stretching.
The above introduces the relevant content in the design of the drawing part processing mold. During the drawing process, there is friction between the material and the die, so there should be a special drawing lubricant. High friction will not only increase the tensile coefficient, but also increase the pulling force, which is detrimental to the scratches on the mold and workpiece surface. I hope the above will be helpful to readers.