Research on Graphite Machining Process 2

In graphite high-speed machining, due to the hardness of the graphite material, the interruption of chip formation and the influence of high-speed cutting characteristics, alternating cutting stress is formed during the cutting process and a certain impact vibration is generated, and the tool is prone to rake face and flank face Abrasion seriously affects the service life of the tool, so the tool used for graphite high-speed machining requires high wear resistance and impact resistance.

Diamond coated tools have the advantages of high hardness, high wear resistance, and low friction coefficient. Currently, diamond coated tools are the best choice for graphite processing.

Graphite machining tools also need to choose a suitable geometric angle, which helps to reduce tool vibration, improve machining quality, and reduce tool wear. German scholars’ research on graphite cutting mechanism shows that graphite removal during graphite cutting is closely related to the rake angle of the tool. Negative rake angle cutting increases the compressive stress, which is beneficial to promote the crushing of the material, improve the processing efficiency, and avoid the generation of large-size graphite fragments.

Common tool structure types for graphite high-speed cutting include end mills, ball-end cutters and fillet milling cutters. End mills are generally used for surface processing with relatively simple planes and shapes. Ball-end milling cutters are ideal tools for processing curved surfaces. Fillet milling cutters have the characteristics of both ball-end cutters and end mills, and can be used for both curved and flat surfaces. For processing.

Cutting parameters

The selection of reasonable cutting parameters during graphite high-speed cutting is of great significance to the improvement of workpiece processing quality and efficiency. Since the cutting process of graphite high-speed machining is very complicated, when choosing cutting parameters and processing strategies, you need to consider the workpiece structure, machine tool characteristics, tools, etc. There are many factors, which mainly rely on a large number of cutting experiments.

For graphite materials, it is necessary to select cutting parameters with high speed, fast feed, and large amount of tool in the rough machining process, which can effectively improve the machining efficiency; but because graphite is prone to chipping during the machining process, especially at the edges, etc. The position is easy to form a jagged shape, and the feed speed should be appropriately reduced at these positions, and it is not suitable to eat a large amount of knife.

For thin-walled graphite parts, the reasons for the chipping of edges and corners are mainly caused by cutting impact, letting the knife and elastic knife, and cutting force fluctuations. Reducing the cutting force can reduce the knife and bullet knife, improve the surface processing quality of thin-walled graphite parts, and reduce corner chipping and breaking.

The spindle speed of graphite high-speed machining center is generally larger. If the spindle power of the machine tool allows, selecting a higher cutting speed can effectively reduce the cutting force, and the processing efficiency can be significantly improved; in the case of selecting the spindle speed , The feed amount per tooth should be adapted to the spindle speed to prevent too fast feed and large amount of tool to cause chipping. Graphite cutting is usually carried out on a special graphite machine tool, the machine speed is generally 3000 ~ 5000r/min, and the feed speed is generally 0. 5~1m/min, select a relatively low speed for rough machining and a high speed for finishing. For graphite high-speed machining centers, the speed of the machine tool is relatively high, generally between 10000 and 20000r/min, and the feed rate is generally between 1 and 10m/min.

Graphite High Speed ​​Machining Center

A large amount of dust is generated during graphite cutting, which pollutes the environment, affects the health of workers, and affects machine tools. Therefore, graphite processing machine tools must be equipped with good dust-proof and dust-removing devices. Since graphite is a conductive body, in order to prevent the graphite dust generated during processing from entering the electrical components of the machine tool and causing safety accidents such as short circuits, the electrical components of the machine tool should be protected as necessary.

Graphite high-speed machining center adopts high-speed electric spindle in order to achieve high speed, and to reduce the vibration of the machine tool, it is necessary to design a low center of gravity structure. The feed mechanism mostly adopts high-speed and high-precision ball screw transmission, and designs anti-dust devices [7]. The spindle speed of graphite high-speed machining center is usually between 10000 and 60000r/min, the feed speed can be as high as 60m/min, and the processing wall thickness can be less than 0. 2 mm, the surface processing quality and processing accuracy of the parts are high, which is the main method to achieve high-efficiency and high-precision processing of graphite at present.

With the wide application of graphite materials and the development of high-speed graphite processing technology, high-performance graphite processing equipment at home and abroad has gradually increased. Figure 1 shows the graphite high-speed machining centers produced by some domestic and foreign manufacturers.

OKK’s GR400 adopts a low center of gravity and bridge structure design to minimize the mechanical vibration of the machine tool; adopts C3 precision screw and roller guide to ensure the high acceleration of the machine tool, shorten the processing time, and adopt the addition of splash guards The fully enclosed sheet metal design of the machine top cover prevents graphite dust. The dust-proof measures adopted by the Haicheng VMC-7G1 is not a commonly used method of vacuuming, but a water curtain sealing form, and a special dust separation device is installed. The moving parts such as guide rails and screw rods are also equipped with sheaths and Powerful scraping device to ensure long-term stable operation of the machine tool.

It can be seen from the specification parameters of the graphite high-speed machining center in Table 1, that the spindle speed and feed speed of the machine tool are very large, which is the characteristic of graphite high-speed machining. Compared with foreign countries, domestic graphite machining centers have little difference in machine tool specifications. Due to machine tool assembly, technology and design, the machining accuracy of machine tools is relatively low. With the widespread use of graphite in the manufacturing industry, graphite high-speed machining centers have attracted more and more attention. High-performance and high-efficiency graphite machining centers are designed and manufactured. The optimized processing technology is adopted to give full play to its characteristics and performance to improve graphite. The processing efficiency and quality of the parts are of great significance to improving my country’s graphite cutting processing technology.

to sum up

This article mainly discusses the graphite machining process from the aspects of graphite characteristics, cutting process and the structure of graphite high-speed machining center. With the continuous development of machine tool technology and tool technology, graphite high-speed machining technology needs in-depth research through cutting tests and practical applications to improve the technical level of graphite machining in theory and practice.