uhp 450mm graphite electrode manufacturers
Ulanchabu graphite electrode high-speed machining
Material characteristics of graphite electrode Ulan Chabu graphite electrode has good strength at high temperature, low thermal expansion coefficient, good workability and good thermal and electrical conductivity. Therefore, graphite electrode is widely used in metallurgy, electric furnace, electric discharge machining and other fields. . In terms of EDM, the development of new graphite electrode materials and its processing technology has expanded the application range of EDM and improved its performance. Compared with copper graphite electrode, graphite electrode has low consumption, fast processing speed, good machining performance, high processing accuracy, small thermal deformation, light weight, easy surface treatment, high temperature resistance, high processing temperature, graphite electrode can be bonded And other advantages. Although graphite is a very easy-to-cut material, the graphite material used as the EDMgraphite electrode must have sufficient strength to avoid damage during operation and EDM processing, and the shape of the graphite electrode (thin wall, small rounded corners, sharp change) ) And so on also put forward higher requirements on the grain size and strength of the graphite electrode, which causes the graphite workpiece to be easily broken during the machining process, and the tool is easy to wear. Therefore, how to prevent the workpiece from breaking, improve the surface processing quality, and reduce the cost of processing tools has become an important issue in graphite electrode processing.
Cutting mechanism and characteristics of graphite materials Masuda (1996), uhp 450mm graphite electrode manufacturers used high-speed photography to observe the turning process of sintered carbon (sintered below 2000°C) and graphite (sintered above 2500°C). It is believed that the chip formation process of the two is as follows: When the cutting edge of the tool is in contact with the workpiece, an expanding crack is generated, and the contact is brittle and broken due to the feed of the tool, and chips are continuously formed. Therefore, the main cutting formation mechanism is brittle fracture. In 1998, uhp 450mm graphite electrode manufacturers studied the graphite high-speed milling process. It was found that the formation of graphite chips is very similar to that of brittle materials such as ceramics. There is crushing at the tip of the tool, forming small chips and small pits. The cracks generated by cutting will extend and expand to the front and bottom of the tool tip, and then expand. To the free surface, fracture pits are formed, which can be explained by fracture mechanics; the contact state between the chip and the rake face of the tool is divided into the cutting contact impact zone and the slip zone of the chip along the rake face, which respectively lead to different tool wear patterns . The cutting force of graphite electrode materials is only about 10% of that of ductile metals such as aluminum and copper, so the cutting force is usually not the focus of research. The experiment measured that the turning temperature of graphite materials is not high. When Vc=500m/min, the maximum temperature is between ℃, and it has a linear relationship with the cutting speed. Based on this inference, even if Vc=500m/min, the cutting temperature will not exceed 500°C, so the cutting temperature will not have much influence on the cutting process. Studies have shown that the main contradiction in graphite material processing is wear. The main tool wear areas for graphite electrode material processing are the rake face and the flank face. On the rake face, the impact contact between the tool and the broken chip area produces impact abrasive wear, and the chips sliding along the tool surface produce sliding friction and wear. The main factors affecting wear: tool material grade, cutting linear speed, feed rate, tool angle, etc.
The wear mechanism of cemented carbide tools when processing graphite electrode materials is as follows: wear occurs in the sliding zone due to micro-cutting and surface fatigue damage; eventually leading to wear of the tool binder phase (Co) abrasive grains and wear resistance phase (WC) , Produce cracks and break off. The wear of polycrystalline diamond tools is composed of the wear of graphite chips on the binder phase and the secondary abrasive wear caused by the crushing of the diamond itself. The surface of the diamond film tool usually has strong graphite adhesion, and there is no crater wear. It belongs to macroscopic impact wear, not mechanical abrasive wear.
uhp 450mm graphite electrode manufacturers tips: The life of diamond film cutting tools can reach 100 times that of ordinary cemented carbide cutting tools, and is better than PCD cutting tools. Therefore, the most suitable graphite electrode high-speed machining tool is: diamond-coated cemented carbide tool. When the graphite electrode is processed at high speed, if the cutting speed increases, although the risk of large-area wear increases, the wear cross-sectional area of the crescent crater decreases.
As the cutting speed increases, the graphite lubricating film formed on the friction surface increases and the surface wear coefficient decreases, so the tool life can be greatly increased. This is also an important reason why high-speed machining strategies are usually used in graphite cutting. Increasing the feed per tooth of the milling cutter, or increasing the cutting width per tooth, increases the average chip thickness, so cutting impact and tool wear increase. The increase of the rake angle of the tool changes the impact angle of the chip particles; the increase of the relief angle increases the sharpness of the tool and the wear of the flank surface decreases; the change of the entering angle changes the direction of cutting force and the actual cutting area, so As the entering angle increases, tool wear also decreases, and tool durability is improved.
Ball-end milling cutters and flat-bottom milling cutters are commonly used for high-speed milling. When a ball end mill is used to process a curved surface, the cutting speed is reduced from the outside to the inside, so the top of the tool is easy to wear. The flat-bottomed end mill can process step contours, and the machining allowance fluctuates strongly. The fluctuating contours of the machined tools cause severe damage to the finishing tools. Comparing these two tools under the same conditions, the cutting distance of the flat-bottomed end mill is longer than that of the ball-end cutter.