According to the processing mechanism analysis of titanium alloy, the cutting force of titanium alloy is only slightly higher than that of ordinary steel with the same hardness, but the physical phenomenon of processing titanium alloy is much larger than that of processing steel, so that the processing of titanium alloy faces great difficulties.
Thermal conductivity and elasticity are the source of defects in titanium machining
"Heat" is the "culprit" of titanium alloy difficult to work! Most titanium alloys have very low thermal conductivity, 1/7 of steel and 1/16 of aluminum. Inoculation occurs during the course of cutting of titanium alloy, therefore, a large amount of heat is very difficult to agile conduction to the artifact or taken away by chip, and agglomeration in cutting area, the inoculation of temperature can be as high as 1000 ℃ above, the accumulation of heat is quite harm, make the cutter blade wear quickly and naturally the devolop tumor, rapid wear the blade, and the cutting area occurs more heat, Further shrinkage tool life. At the same time, the high temperature generated during the cutting process destroys the appearance integrity of titanium alloy parts, leading to various defects in the parts.
How to solve the processing technology of titanium alloy
A. Adopt the blade with positive Angle shape to eliminate the cutting force, cutting heat and deformation of the workpiece.
B. Connect constant feed and stop the hardening of the workpiece. The tool should always be in the feeding state during the cutting process, and the radial bite ae should be 30% of the radius during milling.
C. High pressure and large flow cutting fluid is accepted to maintain the thermal stability of the processing process and prevent workpiece deformation and tool damage caused by excessive temperature.
D, the link blade edge sharp, blunt tool is the cause of heat mobilization and wear, easy to lead to tool failure.
E. Try to process the titanium alloy in the softest state. Because the material becomes more difficult to process after hardening, thermal disposal increases the strength of the material and increases the wear of the blade.
F. Use large tip radius or chamfering to cut, and use more edge area to cut. This eliminates cutting force and heat at each point, preventing local damage. In the milling of titanium alloy, the cutting rate has the greatest effect on the tool life VC, and the radial bite (milling depth) is the second.
How to solve item wear problem
In titanium alloy machining, the blade groove wear is the local wear on the back and front along the cutting depth bias, which is often caused by the hardening layer left by the early processing. The chemical reaction and diffusion of the tool and workpiece material in the processing temperature greater than 800℃ is also one of the reasons for the formation of groove wear.
Due to the accumulation of titanium molecules in the workpiece at the front of the blade in the processing process, it is easy to "weld" to the blade under high pressure and temperature, forming chip tumors. When the chip is removed from the blade, the carbide coating is removed from the blade and the tool life is greatly reduced. Therefore, it is necessary to choose good blade material and shape for titanium alloy machining.
How to solve the problem of tool layout and cooling in titanium machining
The core of titanium alloy machining is the heat problem, to solve the effective loss of heat to solve the larger problem.
First of all, the choice of appropriate or even imported high-end imported liquid, especially the lubrication and cooling cooling liquid, can quickly and agile to reduce the temperature of the tool and workpiece, but also can lubricate, reduce the wear of the material surface, extend the service life of the tool.
Second, a large amount of high-pressure cutting fluid needs to be injected correctly on the cutting edge in real time to dissipate heat quickly, so the layout and design of the machining tool is also critical.