Metal stamping parts using stamping equipment for product drawing molding processing, including: drawing processing, redrawing processing, reverse drawing and thinning drawing processing.

 

Metal stamping parts tensile processing common molding types

details

The use of stamping equipment for product drawing molding processing, including: drawing processing, redrawing processing, reverse drawing and thinning drawing processing.

Tensile processing: using the platen pressing device, the punch pressure of the punch is used to pull part or all of the flat plate into the cavity of the concave model, so that it can be formed into a vessel with bottom. The processing of the side wall parallel to the drawing direction of the container is a simple drawing processing, while the stretching processing of the cone (or cone) shaped container, hemispherical container and parabolic surface container, etc., also includes the expanding processing.

Redrawing processing: for the deep drawing products that cannot be completed by the first drawing processing, the formed products need to be stretched again to increase the depth of the forming container.

Reverse stretching: Reverse stretching of the drawing workpiece in the previous process, the inner side of the workpiece becomes the outer side, and make its outer diameter smaller.

Thinning drawing: Punch is used to squeeze the formed container into the cavity of the concave model, which is smaller than the outer diameter of the container, so that the outer diameter of the container with the bottom becomes smaller and the wall thickness becomes thinner, which not only eliminates the deviation of the wall thickness, but also makes the surface of the container smooth.

Drawing forming

The following types are included in metal stamping and stretching processing using stamping equipment:

 

1. Round drawing: drawing of cylinder products with flanges. The flange and the bottom are planar, the side wall of the cylinder is axisymmetric, and the deformation is uniformly distributed on the same circumference. The blank on the flange produces deep drawing deformation.

Cylinder drawing

2. Ellipse drawing: The blank deformation on the flange is drawn deformation, but the deformation amount and deformation ratio change along with the contour shape. The larger the curvature, the larger the plastic deformation of the blank. On the contrary, the smaller the curvature part, the smaller the plastic deformation of the blank.

Elliptic drawing

3. Rectangular drawing: it can be found a low Rectangular piece formed by one stretch. In the process of stretching, the tensile resistance at the rounded corners in the flange deformation area is greater than that at the straight edges, and the degree of deformation at the rounded corners is greater than that at the straight edges.

Rectangular drawing

(4) Hill drawing: When the side wall of the stamping part is inclined, the side wall is suspended in the stamping process, and the die is not affixed until the end of the forming. The deformation characteristics of different parts of the lateral wall are not completely the same.

Mountain stretching process

5. Hill drawing: The deformation of the blank part in the forming process of the mound cover is not a simple stretching deformation, but a composite forming in which both stretching and bulging deformation exist simultaneously. The deformation of the billet on the pressing surface is tensile deformation (radial is tensile stress, tangential is compressive stress), while the deformation of the billet inside the contour (especially in the central area) is bulging (radial and tangential are tensile stress).

Mound stretching machining

6, With flange hemispherical drawing: when the spherical parts are drawn, the blank is in local contact With the spherical top of the punch, and the rest are in the unrestrained free state of suspension. Therefore, the main technical problems of this kind of spherical part drawing lie in the serious thinning of the local contact part or the buckling of the curved surface part.

Hemispherical drawing with flange

7, Flange drawing processing: the Flange part of the drawing product will be shallow drawing processing. The stress - strain condition is similar to compression flanging. The forming limit is mainly limited by compression and wrinkling due to tangential compressive stress.

Flange drawing processing

8, edge drawing processing: angular redrawing processing is carried out for the Flange part of the previous process, which requires the materials to have good plasticity.

Edge drawing

9. Deep drawing: For products with tensile processing beyond the limit, they need more than two times of stretching before they can be completed. Products that have been drawn in the depth direction at the front work station will be redrawn in the depth direction. A wide flange stretcher is drawn to the required flange diameter at the first stretch, and the flange diameter remains the same during subsequent stretch.

Deep drawing

10, Taper drawing: for h/d>0.8, =10° ~ 30° deep tapered parts, due to the larger depth and larger deformation degree of the blank, the forming force is transferred only by the local area of the blank and punch contact, which is easy to cause the partial excessive thinning of the blank and even rupture, and it needs to be gradually formed after multiple transitions. Step drawing method is to first stretch the blank into a stepped transition part, and the step shape is cut with the inner shape of the conical part, and finally bulge to form a conical shape. The drawing times and process of the stepped transition parts are the same as those of the stepped cylinder parts.

Tapered drawing

11. Rectangular redrawing: It can be found that the deformation of a high Rectangular piece formed by multiple stretching is not only different from that of a deep cylindrical piece, but also greatly different from that of a low box. Figure 1-46 During the processing of high rectangular box by multi-station automatic transfer press, the shape and size of the piece change with the stretching height during the process of multiple drawing.

Rectangle redrawing process

Surface forming (Surface forming) : Surface stretching forming can make the outer flange part of metal slab blank shrink and the inner flange part elongate to form hollow products with non-straight wall and non-flat bottom Surface shape.

Surface forming

13. Step drawing: The initial drawn product on the left is further drawn to form the bottom of the Step on the right. The deeper part deforms at the early stage of the drawing, while the shallower part deforms at the later stage of the drawing. The lateral wall of the changing part of the step is prone to induce shear stress and produce deformation.

Step drawing

14. Reverse drawing: The workpiece processed in the previous process is stretched in Reverse, which is a kind of redrawing. The reverse tensile method can increase the radial tensile stress and has a better effect on preventing wrinkling. It's also possible to increase the coefficient of restretching.

Reverse drawing

15. Ironing: Different from ordinary drawing, Ironing mainly involves changing the thickness of the cylinder wall during drawing. The gap between the convex and concave dies is less than the thickness of the blank, and the straight wall of the blank is under greater uniform compressive stress when passing through the gap. When the wall thickness thins in the process of drawing, the deviation of the container wall thickness is eliminated, the smoothness of the container surface is increased, and the precision and strength are improved.

Thinning tensile processing

Panel drawing: Panel products are stamped parts with complex surface shapes. In the drawing process, the blank deformation is complex, and its forming property is no longer simple drawing forming, but the composite forming of drawing and swelling simultaneously.