At this stage, most of the aero-engine parts are made of titanium alloy materials. According to the assembly requirements, the precision of the surface dimensions and the surface roughness of the finished machining need to be ground to ensure the quality of the surface of the parts. Due to titanium alloy materials
Due to its own physical and mechanical properties, surface burns and reduced surface integrity are likely to occur during grinding. At present, it is urgent to solve the problem of grinding titanium alloy materials, so it is very necessary to select the appropriate grinding wheel.
1 Performance analysis of titanium alloy materials
The types of titanium alloys are roughly divided into three categories, α titanium alloys, β titanium alloys, and α + β titanium alloys. It has a small specific gravity, high specific strength, high-temperature resistance, corrosion resistance, super memory, non-magnetic, low elastic modulus, and biocompatibility.
A series of excellent ones make it used in a wide range of fields. Titanium has a melting point of 1668 ° C and a boiling point of 3400 ° C, which is higher than that of nickel-iron. Therefore, light heat resistance has become an excellent foundation, and it can work at 500 ° C for a long time. New
The long-term working temperature of titanium alloy is even higher, its strength is 300 times higher than that of an aluminum alloy at 300-350 ℃. Commonly used α + β titanium alloy has a strength of 1.2GPa, a specific gravity of 0.44MPa, and a specific strength of 23-27, which are higher than that of alloy steel. Titanium alloy
Its tensile strength can exceed 1.5GPa, and a large force must be applied to its processing, which is a typical difficult-to-process material.
The thermal conductivity of titanium is 0.036cal, and the thermal conductivity of TC11 titanium alloy is even worse. The elastic modulus of titanium is about 1/2 of that of steel. It has a high resilience during processing and is easy to vibrate.
Titanium alloys contain oxygen, hydrogen, nitrogen, carbon, and sometimes also impurity elements such as silicon and iron. These elements react strongly and exist in the lattice in a gap form, which can increase the strength of the titanium alloy and reduce the plasticity.
Fracture toughness, low-temperature toughness, fatigue strength, corrosion resistance, cold forming, and weldability are deteriorated. Titanium alloys are highly chemical at high temperatures. At certain grinding temperatures, titanium forms oxide and nitride protective films, making the surface layer hard
It becomes brittle, reduces elasticity, and increases the degree of work hardening. It is easy to attach during grinding, block the grinding wheel, cause overheating of the grinding, and reduce the surface integrity.
2 Selection of titanium alloy grinding wheels
2.1 Titanium alloy grinding requires small adhesion of the grinding wheel, small wear, easy clogging, and low grinding temperature
This mainly includes the particle size of the abrasive, the tissue shape, and the size of the binder. The ordinary grinding wheel is composed of abrasive bond and pores. The role of the abrasive is to grind the processed material to form a surface that meets the requirements. The role of the binder is to stick the abrasive
Together, a certain shape and hardness are formed, so that the abrasive particles maintain a stable trajectory during the grinding process and can self-detach. The air holes are used for chip removal in the grinding process, cooling, and lubrication. Common abrasives include just
Jade series (alumina), and silicon carbide series. For grinding titanium alloys, silicon carbide grinding wheels should be selected.
2.2 Selection of binder
There are two types of binders: resin and ceramic:
1) The ceramic binder has strong particle capacity, good thermal stability, and chemical stability, waterproof, heat resistance, corrosion resistance, small wear, long-term grinding performance, porosity, not easy to block, and high productivity. Brittle, no
Can withstand large impact loads.
2) The resin bond grinding wheel has high strength, elasticity, good impact resistance, poor thermal stability, poor corrosion resistance, and will soften and lose strength at high temperatures.
Grinding titanium alloy should choose the ceramic bond grinding wheel.
2.3 Selection of granularity
Grinding titanium alloy usually uses 36 # -80 # particle size.
2.4 Grinding wheel structure hardness
Grinding titanium alloy should usually choose soft or medium hardness, loose structure of the large pore grinding wheel.
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