In order to take advantage of the high-speed machining technology and the automatic tool change function represented by the turning machining center and the boring and milling machining center, the machining efficiency is improved, and the processing of complex parts should be based on the principle of centralized operation, that is, in one installation. The centralized processing of multiple processes in the clamps dilutes the boundaries of different cutting processes such as traditional turning, milling, boring and threading, and fully utilizes the high-speed cutting function of equipment and tools. At the same time, new requirements for versatile tools have been proposed. It requires a tool to complete the processing of different parts of the part, reduce the number of tool changes, save time for tool change, reduce the number of tools and inventory, and help manage and reduce manufacturing. cost. More commonly used are multi-purpose turning tools, milling cutters, boring and milling cutters, drilling and milling cutters, drill-milling threads - chamfering and other tools. The use of targeted process strategies on mass production lines requires the development of dedicated, compound or intelligent tools to increase machining efficiency and precision and reduce investment. Under high-speed cutting conditions, some special tools can reduce the processing time of parts to less than 1/10 of the original, and the effect is very remarkable. Previous page next page
Figure 3 shows the high-speed cutting process designed by the author for the machining of the top end of the automobile engine body and the joint surface of the main bearing housing. The body material is gray cast iron, the tool is CBN non-reground composite tool, the spindle speed is 12000r/min, and the cutting allowance is 0.02mm. The two key parts in the picture are milled in place at one time, and the important size A is guaranteed by the compound milling cutter itself. The process also effectively avoids chatter due to the long milling of the main bearing housing joint face, which greatly improves the cutting accuracy, cutting efficiency and surface quality.
FMS: As the product life cycle continues to decrease, the number of varieties continues to increase. In this case, how to shorten the time to replace the product becomes a key issue; how to flexibly adapt the processing equipment (ie, flexibility) due to changes in product design is another major issue. Then, an FMS composed of a highly flexible general-purpose machining center appeared. The "high-flexibility general-purpose machining center" mentioned here is different from the machining center under the general concept. They are specially developed for mass production, which fully meets the conditions for incorporating FMS for mass production, that is, high productivity, It is a high-speed and compact machining center with a small area, easy chip removal, easy installation and displacement, and excellent continuous running performance.
In order to meet the needs of mass production, Mitsubishi Heavy Industries of Japan has adopted this high-speed machining center as the host and developed the so-called “fable FMS†(see Figure 4). The FMS consists of eight M-H5A three-axis machining centers and an unmanned carrier (AGV) carrying two pallets in front of the machine. The truck is used to exchange pallets, reciprocating at pallet loading stations and Between machine tools. The operator only has to carry out the loading and unloading of the workpiece by means of the operation button in one position, and it is not necessary to travel between the machine tools. The vehicle is sequentially in front of the machine tool that is about to complete the processing. After the standby bed is processed, the pallet exchange is performed between the machine tool and the carrier, and then the finished product is returned to the loading and unloading station.
2. High-speed cutting of automobile cover parts and parts molds High-speed milling technology has significant advantages in processing three-dimensional free-form surfaces and super-hard materials.
Auto parts mold: One type of car often needs thousands of molds. In order to adapt to the needs of new models as soon as possible, the outer and inner cover molds and the resin anti-shock forming molds must shorten the production cycle and reduce the production cost. Therefore, high-speed machining is the preferred process solution for such mold manufacturing. After the high-speed, low-cut finishing of the mold, the workload of the fitter is greatly reduced, and the mold manufacturing cycle can be shortened by 40%. For example, the injection mold of the safety door lock adopts high-speed milling, and the hardness of the material is HRC54. The minimum tool diameter that can be used is (φ0.6mm, the maximum depth of cut can reach 4.8mm, the processing time is 3h, and the surface roughness reaches Ra0. .4μm, no need for the fitter process, greatly reducing the processing time.
Automobile cover parts: The inner and outer covers of automobiles, instrument panels, etc. are mostly manufactured by injection molding. These injection molds are generally complex cavity and thin shell structure. Ordinary cutting processing often cannot meet surface roughness and bending at the same time. The accuracy requirements of the degree, in order to carry out appropriate manual finishing. The use of high-speed machining can bring many benefits: 1) higher precision than conventional finishing; 2) high-speed cutting with a small amount of re-cutting, high-speed multiple precision The cutting process greatly reduces the workload of manual dressing and greatly improves the processing efficiency of the cover mold. 3) Since the cutting speed is greatly improved, the machining cycle is greatly shortened compared with the past finishing process.
For example, automobile cover molds are mostly composed of various free curved surfaces. High-speed milling uses high-speed, small-depth deep-cut and large-feed processing methods to improve the manufacturing precision of the molds and prolong the service life of the molds, thereby improving the quality of the injection molded parts. Moreover, under the conditions of large feed speed, the high-speed milling machine has high-precision positioning function and high-precision interpolation function, especially high-precision interpolation of circular arc.