Aluminum alloy wheels have the advantages of light weight, low cost, and high strength, and aluminum has strong thermal conductivity, which can greatly extend the service life of automobile and motorcycle tires, especially high-load truck tires. (According to the test data of the European wheel manufacturer “alcoa”, aluminum alloy wheels can extend the service life of the tire by up to 20%).
2 Project proposal
In recent years, with the continuous improvement of the production technology of wheel manufacturers in the international market, the European and American wheel industry has gradually replaced the traditional wheel production process with strong-rotating aluminum alloy wheels. The domestic wheel industry is also developing towards advanced aluminum alloy wheel production technology. . The following is a typical wheel hub that a certain manufacturer needs to order (Figure 1). The wheel hub material is 6061 alloy aluminum (equivalent to the domestic brand ld30).
3 Wheel Spinning Equipment
Pt30501cnc two-wheel horizontal powerful spinning machine, the diameter of the spinning workpiece is φ100~φ1000mm, the longitudinal stroke of the rotary wheel is 1900mm, and the maximum spinning force is 30 tons. These machine tool parameters show that the spinning machine meets the requirements of the powerful spinning process of the wheel hub.
4 Aluminum alloy wheel spinning process plan
4.1 Spinning performance analysis of wheel hub material 6061 alloy aluminum
6061 aluminum alloy belongs to the cu-mg-si-mn series aluminum-based alloy, and its chemical composition is as follows:
Cu-0.15%~0.4%, mg-0.45%~0.9%, si-0.4%~0.8%, mn-0.15%; the mechanical properties of this material in the solution and aging state are:
Σb≥320mpa, δ5≥12%, ψb≥25%, hb≥120.
Therefore, the index value of spinability of 6061 alloy aluminum in the solid solution and aging state-the single pass limit thinning rate is:
Φmax=ψb/(0.17+ψb)×100%=0.25/(0.17+0.25)×100%=60%.
This index value shows that its rotatability is worse than that of high-strength steel. In the spinning process, it should be heated appropriately if necessary, and the heating temperature of the workpiece is 310℃~350℃. In addition, in order to improve the spinability of aluminum alloy, some mineral elements-antimony and strontium (0.02%) can be appropriately added.
4.2 Selection of wheel spinning process plan
Like this symmetrical dish-shaped wheel hub, the spinning process generally can be split-spinning from a plate or using casting (forging) blanks for powerful spinning forming two processes. The split spinning process is to use a split wheel to split the disc-shaped slab into two equal parts in the middle, and then use the forming wheel to form it gradually; the strong spinning process It is a strong spinning forming process in which the cast aluminum blank or forging blank is subjected to several passes, and the spinning meets the requirements of the profile size of the wheel. The weight of the wheel produced by the strong spinning process can be reduced by about 25% compared with the weight of the forged wheel. This is due to the strong spinning. The process can spin a variable cross-section thickness, and under the premise of meeting the requirements of the strength index of the wheel, the thickness of the wheel hub can be appropriately reduced.
Because the vertical and horizontal ball screws of our pt30501cnc machine tool form an angle of 75°, when the programming track of the rotary wheel moves only in the radial direction of the workpiece, the rotary wheel has a partial displacement in the axial direction during the actual movement of the machine tool, which makes the spinning process The outer edge of the split wheel is subjected to a certain axial pressure, and its reaction force directly acts on the transmission part of the ball screw of the machine tool, which affects the service life and accuracy of the machine tool. Therefore, this structure is not conducive to the split spinning of the wheel hub. Based on the above analysis, we choose a powerful spinning process to form this symmetrical dish-shaped aluminum hub.
4.3 Process route of wheel hub spinning
Precision forging blank first pass strong spinning second pass strong
Rotary forming turns to CNC workshop machine to add finished wheel hub.
5. Process plan implementation process