Process Analysis of Digital Control CNC Machining (1) Structural Features of Parts The material of the part is hard aluminum LY12, which has good cutting performance and belongs to the typical thin-walled disc structure. The outer dimensions are large, and the thickness of the surrounding and internal ribs is only 2mm, cavity depth is 27mm. If the process plan or processing parameters are improperly set during the processing, the parts are easily deformed, resulting in an oversize difference.
(2) Process analysis The blank of the part is selected from bar stock, and the roughing and finishing process plan is adopted. The specific process flow is as follows: blank → rough car → rough milling → aging → fine car → fine milling. Roughing: Reserve 1.5mm finishing allowance on the outer and end faces, and pre-drill the center hole. Rough milling: Reserve a margin of 1.5mm on the side and bottom of the cavity, and pre-drill the process hole at the hole position of φ12mm. Aging: remove material and processing stress. Finishing car: Finishing end face, outer circle and 镗6mm process hole, it is required to complete the clamping once, in order to ensure the coaxiality and lay a good foundation for the subsequent processing. Finishing: The final requirement of the part is guaranteed.
1 Rough milling cavity roughing is mainly to remove the large margin, and lay the foundation for the subsequent finishing, so when processing the cavity, choose low-cost ordinary digital control CNC machining milling machine processing. The process requires that the inner contour be machined according to the part structure diagram shown, the arc corner is R5mm, and the finishing allowance is uniform, which is 1.5mm. Moreover, in this process, it is necessary to pre-process the positioning holes required for finishing in the hole position of φ12 mm. Welcome to the company ***http://
2 High-speed machining technology for finishing milling cavity is a manufacturing technology applied in recent years. In high-speed machining, the cutting force is small, the machining deformation of the parts can be reduced, and it is suitable for thin-walled parts, and the chips are cut off in a short time. Most of the cutting heat is carried away by the chips, and the workpiece is thermally deformed. Small, it is conducive to ensure the size and shape accuracy of the parts; high-speed machining can obtain high surface quality, and the processing cycle is also greatly shortened. Therefore, in combination with the characteristics of such thin-walled disk parts, high-speed machining is used when finishing the cavity.
3 Machining of the positioning hole This part is finished with the center hole φ6mm and φ12mm hole as the positioning hole, so the cavity must be machined into place before finishing the cavity. Cnc CNC machining center hole φ6mm is honed to φ6H8 when the outer circle of the turning precision car is φ301.5mm; the φ12mm hole is drilled by digitally controlled CNC milling machine and hinged to φ12H8.
(3) Positioning and clamping of parts during finishing of the cavity In order to make the workpieces can be quickly and correctly clamped on the machine tool, and it is not necessary to align one by one when machining a batch of workpieces, this processing adopts a positioning method of one pin and two pins. . The φ6mm and φ12mm holes already existing on the parts are used as positioning holes for simple tooling. The tooling uses a cylindrical pin and a flat pin as positioning elements. Since the part belongs to a thin-walled part, it is easy to be deformed. When clamping the workpiece, the pressure plate should be pressed at a part with good rigidity of the workpiece, and the distribution should be as uniform as possible to ensure the reliability of the clamping, and the clamping force should be appropriate. In order to prevent the positioning of the workpiece or to cause an unacceptable deformation of the workpiece. Its specific positioning and clamping. This clamping method fully conforms to the characteristics of the machining center, and the one-clamp can complete the machining of the cavity and all the holes.
