Metal stamping and stretch forming, as one of the primary stamping processes, has been widely applied. Various thin-walled parts with cylindrical, rectangular, stepped, spherical, conical, parabolic, and other irregular shapes can be manufactured through the drawing process. So today, Kechuang Hardware Stamping Factory would like to share with you: what are the different types of metal stamping and stretch forming processes.
When using stamping equipment for metal stamping and drawing operations, the following 16 types are included:
- Cylindrical shell drawing process: Drawing of cylindrical products with flanges. Both the flange and bottom surface are flat, the side wall of the cylinder is axisymmetric, the deformation is uniformly distributed on the same circumference, and the blank on the flange undergoes deep drawing deformation.
- Elliptical drawing process: The deformation of the blank on the flange is drawing deformation, but the deformation amount and deformation rate change correspondingly along the contour shape. The greater the curvature, the greater the plastic deformation of the blank. Conversely, the smaller the curvature, the smaller the plastic deformation of the blank.
Metal stamping and drawn parts. - Rectangular deep drawing process: Low rectangular parts formed in a single drawing operation. During drawing, the drawing resistance at the corner areas of the flange deformation zone is greater than that at the straight edge areas, and the deformation degree at the corners is greater than that at the straight edges.
- Conical drawing process: When the side wall of the stamped part is inclined, the side wall remains suspended during the stamping process and does not adhere to the die until the end of forming. The deformation characteristics of different sections of the side wall during the forming process are not completely identical.
- Dome-shaped drawing process: During the forming of dome-shaped cover plates, the deformation of the blank is not a simple drawing deformation, but a composite deformation where drawing deformation and bulging deformation coexist simultaneously. The deformation of the blank on the pressing surface is drawing deformation (radial tensile stress and tangential compressive stress), while the deformation of the blank inside the contour (especially in the central region) is bulging deformation (including both radial and tangential tensile stresses).
- Flanged hemispherical drawing process: When drawing spherical parts, part of the blank comes into contact with the spherical top of the punch, while most of the remaining portion is in an unconstrained free state. Therefore, the main process issues in drawing such spherical parts are severe thinning in the locally contacted areas, or instability and wrinkling in the curved surface portions.
- Flange drawing process: Shallow drawing is performed on the flange portion of the drawn product. The stress and strain conditions are similar to those of blank-holder flanging. Due to the presence of tangential compressive stress, wrinkling is prone to occur, so the forming limit is mainly restricted by compressive wrinkling.
- Edge stretching: In the previous process, angular re-stretching is performed on the flange of the stretched product. This processing requires the material to have good plasticity.
- Deep drawing: Stretched products that exceed the stretching processing limit require multiple drawing operations to complete. The product stretched in the depth direction at the front end is re-stretched in the depth direction. For wide-flange stretched parts, the first drawing stretches to the required flange diameter, and the flange diameter remains unchanged during re-stretching.
- Tapered deep drawing: For deep tapered parts with h/d>0.8 and α=10°–30°, due to the large depth, the blank deformation is relatively large, and the forming force is transmitted only through the local area in contact with the punch. This can easily cause excessive thinning or even cracking of the blank locally, requiring multiple transitions to gradually form. The stepped stretching method first stretches the blank into a stepped transition piece, whose stepped shape is tangent to the internal shape of the tapered part, and finally expands the blank into a tapered shape. The number of drawing operations and the drawing process for the stepped transition piece are the same as for stepped cylindrical parts.
- Rectangular re-drawing: The deformation of high rectangular parts formed by multiple drawing operations is not only different from that of deep cylindrical parts, but also significantly different from that of low box-shaped parts. Figure 1-46 shows the changes in the shape and dimensions of the part with the drawing height during multiple drawing operations when processing high rectangular box-shaped parts on a multi-station automatic transfer press.
- Surface forming: Surface stretching forming causes the outer flange portion of the metal flat blank to shrink and the inner flange portion to stretch, forming a hollow product with non-flat walls and a non-flat bottom surface shape.
- Step stretching: The initially stretched product on the left is re-stretched to form a stepped bottom on the right. Deeper parts deform during the early stages of drawing and forming, while shallower parts deform during the later stages. Shear stress is easily generated on the side walls at the step transition, causing deformation.
- Reverse drawing: Reverse drawing is a type of re-drawing in which the workpiece stretched in the previous process is reverse-drawn. The reverse drawing method can increase radial tensile stress and achieve better results in preventing wrinkles. It can also increase the drawing coefficient for re-drawing.
- Ironing (wall thinning): Unlike ordinary drawing, ironing mainly changes the wall thickness of the drawn part during the drawing process. The clearance between the punch and die is less than the blank thickness. When the straight wall portion of the blank passes through the clearance, it is under a large uniform compressive stress. While the wall thickness is reduced during drawing, deviations in the wall thickness are eliminated, the surface area of the container is increased, and the smoothness, precision, and strength are improved.
- Cover panel drawing: Cover panel products are sheet metal stampings with complex surface shapes. During the drawing process, the deformation of the blank is complex, and its formability is no longer simple drawing forming, but a composite forming process where drawing and bulging coexist.
What are the types of metal stamping and drawing forming processes? Mainly the 16 types mentioned above. Balford Hardware Stamping Factory mainly deals in: various precision hardware stamping dies, hardware stamping springs, automotive hardware accessories, precision deep-drawn parts, hardware clips, heat sinks, CNC machining parts, mobile power supply housings, etc. The company has advanced mold design software, senior design engineers, and mold manufacturing technicians. Relying on professional design technology, combined with years of production practice experience, based on high quality, and oriented by market demand, it cooperates closely with multiple research organizations at home and abroad, enabling high-tech to be applied to the company's products in real time. Welcome to call for consultation.