The metal drawing process should be combined with the actual situation, comprehensively consider all aspects of quality, strength, environment and production, and choose a reasonable process plan, so that the production can reduce the process input as much as possible on the basis of ensuring that the production is achieved on the basis of the drawings.
The type of metal deep drawing process
- Cylinder stretching: stretching of flanged cylinders. The flange and the bottom are both straight, the cylinder is axisymmetric, the deformation is uniform on the same circumference, and the blank on the flange is deep-drawing deformation.
- Elliptical stretching: The blank on the flange is stretched and deformed, but the deformation amount and the deformation ratio change accordingly. The larger the curvature of the part of the blank, the greater the deformation; the smaller the curvature of the part of the blank, the smaller the deformation.
- Rectangular stretching: a low rectangular piece formed by one-time stretching. During stretching, the tensile resistance at the rounded corners of the flange deformation zone is greater than that at the straight edge, and the deformation degree at the rounded corner is greater than that at the straight edge.
- Mountain-shaped stretching: the side wall is suspended during the process, and the mold is not attached until the end of forming. The deformation characteristics of different parts of the side wall during forming are not exactly the same.
- Dome-shaped stretching: The blank deformation of the dome-shaped cover plate during the forming process is not a simple stretching deformation, but a composite forming in which stretching and bulging deformation exist at the same time.
- Hemispherical stretching with flange: when the spherical part is stretched, the blank is partially in contact with the spherical top of the punch, and most of the rest are in a suspended state.
- Flange stretch: shallow stretch the stretched flange part. The stress-strain situation is similar to compression flanges.
- Edge stretching: angular re-stretching of the flange part requires good deformation of the material.
- Deep stretching: It can be completed after more than two times of stretching. The wide flange stretched part is stretched to the required flange diameter when it is first stretched, and the flange diameter remains unchanged when it is stretched again.
- Conical drawing: Due to the large degree of deep deformation of deep conical parts, it is very easy to cause local excessive thinning or even rupture of the blank, and it needs to be gradually formed through multiple transitions.
- Rectangular re-stretching: The deformation of high rectangular parts that are formed by multiple stretching is not only different from the stretching of deep cylindrical parts, but also greatly different from the deformation of low box-shaped parts.
- Curved surface forming: The curved surface is stretched and formed, so that the outer flange part of the metal flat blank is reduced, and the inner flange part is elongated, and it becomes a stamping forming method of a curved surface shape with a non-straight wall and a flat bottom.
- Step stretching: the initial stretching is re-stretched to form a stepped bottom. The deep part is deformed in the early stage of stretching, and the shallow part is deformed in the later stage of stretching.
- Reverse stretching: Reverse stretching of the workpiece stretched in the previous process is a kind of re-stretching. The reverse stretching method can increase the radial tensile stress, and can achieve better results in preventing wrinkling. It is also possible to increase the stretch factor for redrawing.
- Thinning stretching: Different from ordinary stretching, thinning stretching mainly changes the thickness of the barrel wall of the stretching part during the stretching process.
- Panel stretching: The surface shape of the panel is complex. In the drawing process, the deformation of the blank is complex, and its forming properties are not simple drawing forming, but a composite forming in which deep drawing and bulging exist at the same time.
Types of Metal Stamping and Drawing
- Stretching process: use the platen device and the punching force of the punch to pull part or all of the flat plate into the cavity of the concave mold to form a container with a bottom. The processing of the side wall of the container parallel to the drawing direction is a simple drawing processing, while the drawing processing of the conical or pyramid-shaped container, the hemispherical container and the parabolic container, etc., also includes the expansion processing.
- Thinning and drawing processing: use a punch to squeeze the formed container into a concave mold cavity slightly 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 wall thickness deviation , and also make the surface of the container smooth.
- Re-stretching: that is, for deep-drawn products that cannot be completed by one-time stretching, the stretched shaped products need to be stretched again to increase the depth of the forming container.
- Reverse drawing processing: reverse drawing of the drawn stamping parts in the previous process, the inner side of the workpiece becomes the outer side, and the outer diameter is reduced.