The processing difficulty of titanium alloy precision parts is not high, just because you have not found the right method

by:NJPE     2020-01-20
1. physical Phenomena of titanium processing the cutting force of titanium alloy precision parts is only slightly higher than that of steel with the same hardness, but the physical phenomena of processing titanium alloy are much more complicated than that of processing steel, thus making titanium alloy processing face great difficulties. The thermal conductivity of most titanium alloys processed by titanium alloy precision parts is very low, only 1/7 of steel and 1/16 of aluminum. Therefore, the heat generated in the process of cutting titanium alloy will not be quickly transferred to the workpiece or taken away by chips, but will gather in the cutting area, and the generated temperature can be as high as over 1 000 ℃, the cutting edge of the cutting tool is rapidly worn, cracked and a chip accumulation tumor is generated, the worn cutting edge is rapidly generated, and more heat is generated in the cutting area, thus further shortening the service life of the cutting tool. The high temperature generated in the cutting process damages the surface integrity of titanium alloy parts at the same time, resulting in a decrease in geometric accuracy of parts and a work hardening phenomenon that seriously reduces their fatigue strength. The elasticity of titanium alloy may be beneficial to the performance of parts, but in the cutting process, the elastic deformation of workpieces is an important reason for vibration. The cutting pressure makes the 'elastic' workpiece leave the tool and rebound, thus making the friction phenomenon between the tool and the workpiece greater than the cutting effect. The friction process will also generate heat, which will aggravate the problem of poor thermal conductivity of titanium alloy. This problem is even more serious when processing easily deformed parts such as thin-walled or annular parts. It is not easy to process titanium alloy thin-walled parts to the expected dimensional accuracy. Because as the workpiece material is pushed away by the tool, the local deformation of the thin wall has exceeded the elastic range and plastic deformation is generated, and the material strength and hardness of the cutting point are obviously increased. At this time, the machining according to the originally determined cutting speed becomes too high, further leading to sharp wear of the tool. Titanium alloy precision parts processing difficult 'hot' is the 'culprit '! 2. On the basis of understanding the processing mechanism of titanium alloy precision parts and previous experience, the main technological know-how for processing titanium alloy is as follows :(1) Use positive angular geometry blades to reduce cutting force, cutting heat and workpiece deformation. (2) Keep constant feed to avoid hardening of the workpiece. During cutting, the tool should always be in the feed state. During milling, the radial cutting amount a e should be 30% of the radius. (3) High-pressure and large-flow cutting fluid is adopted to ensure the thermal stability of the processing process and prevent surface degeneration of workpieces and tool damage caused by high temperature. (4) Keep the blade sharp, blunt tool is the cause of heat accumulation and wear, easy to lead to tool failure. (5) Processing in the softest state of titanium alloy as much as possible, because the hardened material becomes more difficult to process, heat treatment improves the strength of the material and increases the wear of the blade. (6) Use a large tip arc radius or chamfer to cut as many edges as possible into the cutting. This can reduce the cutting force and heat at each point and prevent local damage. When milling titanium alloy, cutting speed has the greatest influence on tool life vc among various cutting parameters, and radial cutting amount (Milling depth)AE is the second. 3. Starting from the blade to solve the difficult problem of titanium processing the wear of the blade groove during the processing of titanium alloy precision parts is the local wear of the back and front along the cutting depth direction, it is often caused by the hardened layer left by the pre-processing. The chemical reaction and diffusion between the tool and the workpiece material at the processing temperature exceeding 800 ℃ are also one of the reasons for groove wear. Because during the processing process, the titanium molecules of the workpiece accumulate in front of the blade and are 'welded' to the blade under high pressure and high temperature to form chip accumulation. When the chip tumor is peeled off from the blade, the hard alloy coating of the blade is taken away. Therefore, the processing of titanium alloy precision parts requires special blade materials and geometric shapes. 4. The focus of titanium alloy processing is heat. A large amount of high-pressure cutting fluid should be sprayed onto the cutting edge in time and accurately so as to quickly remove heat. There is a unique structure of milling cutter specially used for titanium alloy processing on the market. The article comes from the internet. If it involves copyright issues, please contact us in time to make changes!
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