1. Principle of rapid spinning method on Metal Spinning Machine
Stretch spinning mainly relies on the elongation deformation of the blank along the radial direction to realize the bending deformation of the blank. During this process, the elongation of the outer surface of the blank in the thickness direction is greater than that of the inner surface, and the surface of the material changes from a plane to a concave spherical surface. During the forming process, the change of the spherical surface of the blank can be clearly seen.
The spinning method of the super large spherical surface is to fix the periphery of the metal plate with a certain thickness and good ductility on the circular flange mold. In order to ensure that the plate and the supporting flange are fastened, the flange and the aluminum plate are placed on the platform of the large vertical lathe, raised to the height required by the product drawing, and then the positive fixture is found. Use the special spinning device to edit the spherical arc curve program, and adopt the equidistant correction processing scheme to make the plate rotate rapidly layer by layer and press down according to the arc track, so as to realize the rapid forming of the spherical surface.
2. Tool design
According to the spherical surface requirements of various sizes inside and outside the same type of products. After research, it is determined that in the super-large spherical spinning process, it is necessary to design a universal tool to achieve the platform standard, that is, a tool with a similar range and smaller than the tool can be selected, and the tool can be supported uniformly to save processing costs.
(1) Supporting fixture design and material clamping and positioning The aluminum plate should be fixed on the fixture of the supporting flange fixture of the same diameter. The clamp plays the role of fixing and supporting, and it is rotated downward.
In the spinning process, the processing method of programming and offset Z-axis profiling is adopted. That is to say, the center of the material is formed first, and gradually extends to the edge, which facilitates the flat and uniform fastening and pressing of the blank aluminum plate, and avoids the phenomenon of stretching deformation and folding at the spinning stretched edge.
(2) In order to avoid indentation on the inner surface during the drawing process and affect the surface roughness, and effectively avoid the wrinkling phenomenon in the center of the product caused by the increase in the surface area of the inner surface after repeated spinning, the wheel material is made of non-metallic polyurethane. Manufacture of roll stands, auxiliary devices for mounting rolls on tool holders. In order to ensure good performance, the roller frame is made of 45 tempered steel as a whole. The clamping handle part of the roller stand is designed as a parallelogram with an inclination of 37 degrees. After clamping, a helical cutting angle of 8 to 10 degrees is naturally formed, which makes the cutting process easier and more stable.