The main reason is that the debris is mechanically embedded in the gap of the grinding wheel, and there is no chemical adhesion between the debris and the abrasive particles. The formation process of adhesive plug is that chemical bond is formed when the Oriole and abrasive particles break through, and then the debris are fused and welded with each other under the action of mechanical adhesion and pressure to form adhesive plug.
It is a complicated problem why chemical adhesion can be formed between wear debris and abrasive particles. There are different chemical bonding mechanisms between different abrasives and different workpiece materials.
When grinding carbon steel on a surface grinder, when the abrasive grains rub or grind on the metal surface, the wear of the abrasive grains begins, that is, the sharp edges of the abrasive grains begin to be ground, which forms several planes on the abrasive grains. The surface becomes larger and larger, and even the friction force acting on the abrasive grains is large enough to cause the sand particles on the grinding wheel surface to fall off or break, thus exposing new grinding edges. At this time, the blockage of the grinding wheel is caused by the grinding debris embedded in the gap.
When grinding titanium alloy, the grinding will adhere to the sharp peak of abrasive particles. With the rapid development and growth of this kind of adhesive, the working abrasive particles, bond and the surface of the gap are sealed by the adhesive. At this time, the grinding conditions deteriorate rapidly, the grinding force and grinding heat increase sharply, and the surface quality of the workpiece also deteriorates obviously. When the grinding continues and the grinding force reaches a certain level, the adhered debris and the abrasive particles fall off together, revealing new abrasive particles, and the adhesion starts on the new abrasive particles. In this process, the cutting edge of the abrasive grains is almost free of wear marks and is covered by the debris. In the case of blocking and passivation, in order to keep grinding going, whether dressing the grinding wheel or squeezing out the surface sand particles will accelerate the grinding wheel loss. This is the reason why the grinding ratio of titanium alloy is low.
Through the above detection and analysis, we can see that the grinding wheel blocking mechanism of surface grinder grinding titanium alloy mainly includes the following points.
① In the grinding process of ferroalloy, due to the effect of grinding temperature, Ti02 and ti202 are easy to be generated. The hardness of the oxide is basically equivalent to that of corundum grinding wheel. The material with the same hardness is easy to bond under high temperature and high pressure.
② Ti202 and A1203 have the same crystal structure and similar lattice parameters, so alz03 and ti203 have good affinity.
③ Ti element has high chemical activity and is easy to form compounds with carbon, nitrogen and oxygen. This compound is easy to form a solid solution of aluminum titanate A1203 · ti202 with corundum, which makes titanium and corundum have strong combination and form new compounds.
④ The thermal expansion rate of titanium oxide is close to that of corundum, which improves the adhesion reliability of corundum.
Due to the above reasons, it is easy to produce chemical adhesion between sand and debris when Grinding Titanium Alloy on a surface grinder, resulting in wheel blockage. When the abrasive edge is covered by the first chemical adhesive layer, the grinding ability is greatly reduced. The later grinding is carried out in the sliding and extrusion process between the adhered debris and the surface to be machined, and the grinding force and friction heat increase sharply. This state of high temperature, high pressure and high friction force promotes the pressure welding process between the grinding chip and the grinding chip. This kind of multi unit grinding chip repeatedly press welding with each other, forming the blocking of the grinding wheel. This is the formation mechanism of adhesive plugging.
On 2018-08-08 11:45:46
