Water Filtration,Wastewater Treatment,Granular Activated Carbon Coal-Based Activated Carbon,Activated Carbon Co., Ltd. , http://www.nbactivatedcarbon.com
10 years ago, the processing center's rapid moving speed <18m / min, tool change speed > 10s, its performance is not the same as today's machining center. At that time, the cost of using flexible processing lines consisting of machining centers was also very expensive. Due to the structural problems of the tooling and tool magazines of the early machining centers, the special machines must be used in some processes, especially for the processing of key holes.
With the continuous advancement of technology, new types of tools have emerged in an endless stream, and the above problems have now been basically solved. The modern high-speed machining centers with spindle speeds above 12000r/min are all in one, and flexible production lines consisting entirely of machining centers are also widely used. However, at this time, another problem is placed in front of people: Under what circumstances is the processing center selected?
The machining examples exemplified in this paper compare and analyze the performance of three machine tools with different performances under roughing and semi-finishing and finishing conditions.
Roughing and semi-finishing
In flexible machining, the roughing machine provides a stable blank for the final finishing, so the roughing process is a very important part of the flexible machining line. The principle of selecting the roughing process is to select a machining center that meets the rigidity according to different processing materials. However, there are still quite a few engine manufacturers that do not pay attention to which machine tools should be used in the roughing process.
At present, most of the engine blocks used in domestic engine factories use cast iron structures. Compared with the imported blanks, the domestic rough processing margin is large and uneven, and the material is also unstable. Therefore, the machine tools used by domestic engine factories in this process should be relatively higher than the machine tools used in the same process abroad.
Processing example
Take the example of completing the 4108 diesel engine rough cylinder hole:
Cylinder material: HT250
Cylinder hole diameter: 110mm
Unilateral margin: 5mm
Machining parts: rough milling top surface, rough milling bottom surface, rough milling front and rear end faces, rough cylinder bore
The comparison test was carried out with three different performance machines of A, B and C. The main parameters of the machine are shown in Table 1.
The tool materials available for the machining process are as follows:
1. Carbide coated blade: The blade has good toughness, safety and reliability, low line speed and low price, and is suitable for rough blanks.
2, cermet blade: blade toughness, easy to chip, high line speed, medium price, suitable for good quality blanks.
Due to the unstable quality of domestic blanks, it is recommended to use carbide coated blades. For the cutting manual, the Vc is 150-240m/min. It is recommended to use the feed speed of 180m/min. The process determines the spindle speed when roughing the cylinder bore. It is 520r/min.
High-speed machining is a relatively traditional machining system. It consists of two layers of meaning: high spindle speed and high feed rate, which is achieved by using high-performance machine tools in the usual sense of several times or even dozens of times. The high precision and high efficiency of the workpiece processing ultimately achieve the purpose of improving productivity. However, does the selection of a high-speed machining center mean that productivity can be improved? The answer is not the case.