Why do we think titanium alloy is a refractory material?Due to the lack of in-depth understanding of its processing mechanism and phenomenon.
1. Physical Phenomena Of Titanium Processing
The machining force of titanium alloy is only slightly higher than that of steel of the same hardness, but the physical phenomenon of [SCALE STEEL]machining titanium alloy is much more complicated than that of machining steel, so the machining of titanium alloy is faced with great difficulties.
Most titanium alloys have very low thermal conductivity, only 1/7 of that of steel and 1/16 of that of aluminum.Therefore, in the process of cutting of titanium alloy heat will not quickly passed to the workpiece or taken away by chip, and[SCALE STEEL] agglomeration in cutting area, the temperature can be as high as 1000 ℃ above, make the cutter blade rapid wear, cracks, and generate the devolop tumor, rapid wear of the blade, and make the cutting area produces more heat and further shorten the life of cutting tools.
The high temperature in the cutting process also destroys the surface integrity of titanium alloy parts, which leads to the decrease of geometrical [SCALE STEEL]accuracy of the parts and the severe work hardening phenomenon that reduces their fatigue strength.
The elasticity of titanium alloys may be beneficial to the performance of the parts, but the elastic deformation of the workpiece is an important cause of vibration in the cutting process.The cutting pressure causes the "elastic" workpiece to leave the tool and bounce back, so that the friction phenomenon between the tool and the workpiece [SCALE STEEL]is greater than the cutting action.The friction process also produces heat, aggravating the poor thermal conductivity of titanium alloys.
This problem becomes more serious when machining thin-walled or annular parts, and it is not easy to process thin-walled titanium alloy parts to the expected dimensional accuracy.As the workpiece material is pushed away by the tool, the local deformation of the thin wall has exceeded the elastic range and produced plastic deformation, the strength and hardness of the cutting point material are obviously added.At this point, machining at the previously determined cutting speed becomes too high, further leading to rapid tool wear and tear.
2. Process Tips Of Titanium Alloy
On the basis of understanding the processing mechanism of titanium alloy and adding the previous experience, the main process tips of[SCALE STEEL] titanium alloy processing are as follows:
(1)The product adopts the positive Angle geometric shape of the blade, in order to reduce the cutting force, cutting heat and workpiece deformation.
(2) Adhere to a constant feed to avoid hardening of the workpiece, the tool should always be in the feed state during the cutting process, the radial draft AE should be 30% of the radius of the milling.
(3) The use of high pressure and large flow of cutting fluid to ensure the thermal stability of the processing process, to prevent too high [SCALE STEEL]temperature resulting in the workpiece surface denaturation and tool damage.
(4)If the blade edge is sharp, blunt tool is the cause of hot assembly and wear, easy to lead to tool failure.
(5) as far as possible in the titanium alloy in the most soft state processing, due to the hardened material becomes more difficult to process, heat treatment to improve the strength of the material and add the wear of the blade.
(6)Use a large tip arc radius or chamfer cut, as much as possible into the blade into the cutting.This reduces the cutting force and heat at each point and prevents local damage.When milling titanium alloy, the cutting speed has the [SCALE STEEL]greatest influence on tool life VC, followed by radial draft (milling depth) AE.
3. Start With The Blade To Deal With The Titanium Processing Problem
The blade groove wear in titanium alloy processing is the local wear behind and in front along the direction of cutting depth, it is often due to the early processing left by the hardened layer formed.The chemical reaction and diffusion between the tool and the workpiece material at the processing temperature of over 800℃ is also one of the causes of trench wear.During the machining process, titanium molecules of the workpiece accumulate in the front of the blade and are "welded" to the blade under high pressure and temperature, forming a chip tumor.When the chip is removed from the blade, the carbide coating of the blade is taken away, so titanium alloy processing requires special blade material and geometry.
4. Tool Structure Suitable For Titanium Processing
Titanium alloy processing focus is heat, a lot of high [SCALE STEEL]pressure cutting fluid to timely and accurate injection to the cutting edge, can quickly remove the heat.There are special milling cutter structures for titanium alloy processing on the market.