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Molding technology of superhard material resin abrasives (2)
- Nov 08, 2018 -

(1) Aluminum matrix


At present, forged aluminum alloy materials are commonly used as substrates in China. It belongs to the A1-Mg-Si-Cu alloy system and has high strength, good plasticity and workability. The mechanical properties (such as strength and rigidity) of forged aluminum alloys are between steel and phenolic resin, which means that its performance is closer to that of steel than steel. Therefore, it is more widely used in resin grinding wheels.


The shape and size of the base are adapted to the grinding wheel and can be machined on the machine. The surface roughness of the machined surface generally reaches Ra 6.3 μm or more; in order to bond firmly with the transition layer, grooves and hob flowers are often formed on the joint surface. The joint surface is wider and can open multiple grooves. The joint surface is narrow and cannot be grooved, only knurling. The groove is generally a straight groove with a depth of 1 to 2 mm. Large-size substrates can also be deepened, but the groove depth should be proportional to the groove width. In the narrow and deep trenches, the material has a low density after pressing, and the strength is low, which does not enhance the effect. In order to facilitate the molding and simplify the mold structure, for the shaped wheel base, a simple shape similar to the parallel grinding wheel is generally formed before the forming, and the accurate geometric shape required for the post-processing method is used after the forming is cured.


(2) bakelite matrix


Generally, it can be made by hot pressing of 11-10 bakelite powder. The bakelite powder has a small specific gravity, and the manufactured abrasives are lighter and have better elasticity, and are suitable for making various sharpening grinding wheels of small specifications. The manufacturing process is simple, the cost is low, but the processing performance is poor.


(3) phenolic aluminum powder matrix


There are two manufacturing methods in industrial production: (1) The phenolic resin powder and the aluminum powder are firstly mixed uniformly, then hot pressed into a basic shape, and finally processed into a desired base shape. 2 firstly cast diamond layer material, cold press to the required size, then put the base material mixed with phenolic resin powder and aluminum powder, and finally hot press forming. Its characteristics are: the weight is slightly lighter than the aluminum matrix, the elasticity is better, the thermal conductivity is better than the bakelite matrix, the diamond layer and the substrate are very firmly connected, but the mold structure is complex and the operation requirements are high.


Different types of matrix materials have different mechanical properties and will have a certain impact on the grinding effect. Such as:


1. Relationship between matrix performance and grinding ratio: The grinding ratio (G value) of the grinding wheel decreases as the elastic modulus E of the substrate increases. That is to say, the grinding ratio drops rapidly as the rigidity of the grinding wheel increases.


2. The relationship between the matrix and the quality of the machined surface: The general rule is that the grinding wheel with low modulus of elasticity and high grinding ratio has low surface roughness. The matrix of phenolic aluminum powder is higher than that of aluminum matrix, and the steel matrix is the lowest.


3. The relationship between the matrix and the grinding efficiency: Within a certain range, the grinding efficiency of the grinding wheel increases as the flexibility of the matrix increases (the value of E decreases), but when the flexibility is too high (the E value is very small), the G value Very high, the grinding wheel wears little, and the efficiency is reduced.


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