Spinning Technical Solution
Date: Dec,18 2019 View:
Spinning Technical Solution
The spinning technical solution is a process design that must be carried out in the following aspects before the spinning part is specifically formed. In addition to the equipment aspect, it is a crucial link for the success of spinning forming.
l Temperature. For some refractory metals with poor plasticity under trial conditions, such as copper, tungsten, molybdenum, tantalum, niobium, magnesium-aluminum and other alloys, they can be successfully forming under heating conditions. As long as the product quality allows, heat spinning can be used to lower the requirements for power and stiffness of spinning equipment, increase the thickness of the spinning blank and the thinning amount of the spinning parts, shorten the spinning operation time, improve production efficiency and reduce spinning costs.
l Roller. Conventional roller material: T10, T12, GCr15, W18Cr4V，CrWMn, Cr12MoVA, 3Cr12W8V, Cr12,30CrMnSiA, 9CrSi and cemented carbide. Heat spinning roller material: 3Cr2W8V,Cr12Mo and P18. Generally, the medium precision of the roller does not have much influence on the forming itself. But to make the workpiece highly accurate, it is necessary to use a roller with small radial runout of the profile. When there is a special high requirement on the dimensional accuracy of the workpiece, the high precision of the roller is required, and its runout is not bigger than 3-5 μm. In the case of shear forming and thinning of cylindrical parts, the roller runout is not bigger than 0.01 mm.
l RPM (Revolutions Per Minute). Reasonably select the spindle speed when spinning. If the rotation speed is too low, the edges of the blank will wrinkle with increasing the forming resistance and even causing the workpiece to crack. Since increasing the speed can improve productivity and surface quality of the part, if possible, a higher spindle speed should be selected as much as possible. The forming ratio of each spinning cannot exceed its forming limit ratio, otherwise cracking will occur.
l Feed. The roller feed speed is the linear speed at which the contact point between the roller and workpiece moves along its generatrix direction. The effect of roller feed speed varies with the type of material and depends on the specific situation. For the conventional spinning, increasing roller feed speed is easy to wrinkle. Conversely, if the feed speed is too low, the times of frictional contact with the workpiece and the spinning paths increases, which will increase the frictions times at the same part of the workpiece and be stretched to reduce the thickness of the workpiece and rupture. For flow forming of the cylindrical part, the small feed speed will also make the workpiece longer. Therefore, if there is not wrinkle, a large roller feed speed should be selected as much as possible to achieve higher production efficiency.
l Gap. During spinning, the wall thickness of the spinning part depends on the adjustment of the gap between the roller and core mold. This adjustment is an indispensable process for the pre-spinning of all new products. It is also related to the size and accuracy of the post-spinning part. If the gap is adjusted according to the required wall thickness, the actual wall thickness obtained after spinning will be greater than the required wall thickness. The reason includes two parts. On the one hand, the spinning process system (equipment, core mold, roller, etc.) will elastically deform under the action of the spinning pressure, resulting in the concession of the roller relative to the core mold, thereby expanding the original adjustment gap. On the other hand, due to the spinning part itself will also have a certain elastic recovery after deformation, which slightly increases the wall thickness value obtained by the spinning deformation.
l Path. Path means the track of roller motion. Spinning path specifications is explained below in terms of two spinning methods, conventional spinning and shear forming. From the perspective of practical applications, the former has more spinning paths, and the rotary trajectory of the roller is also more complicated. Its influencing factors are also many, often needs careful consideration and necessary correction. Relatively speaking, the latter has less number of paths and the rotary motion trajectory is simpler and easier to operate.
