Reasonable selection of sharpening wheels is one of the key factors to ensure the quality of tool sharpening. Hard alloy saw blades with welded teeth should be sharpened with diamond grinding wheels. The performance indicators of diamond grinding wheels include abrasive grain size, binder type, grinding wheel hardness, grinding wheel structure, grinding wheel shape, grinding wheel size, diamond concentration, diamond layer thickness and material layer Width etc.
The abrasive of the diamond (JR) grinding wheel is a synthetic diamond synthesized under high pressure and high temperature with graphite as raw material under the action of a catalyst. Its main component is carbon (C), which is colorless and transparent, light yellow, yellow-green and black. Wait for several colors. Synthetic diamond abrasives have extremely high hardness and are currently commonly used abrasives for sharpening carbide tools. Compared with silicon carbide, the sharpening productivity is 5 times higher, the roughness is 1 to 3 higher, and the tool durability is 1 to 3 times higher. Diamond grinding wheels are expensive and have poor toughness, especially strong affinity for iron group elements, and poor thermal stability. They will graphitize when the temperature reaches 700-800℃ in air medium, so they cannot be used to sharpen steel tools.
Diamond grinding wheel is expensive, so only the working part of the grinding wheel is composed of diamond and bond abrasive layer. The thickness of the material layer is usually only 1.5mm, 2mm, 3mm and 5mm. The particle size standard of diamond grinding wheels is the same as that of ordinary grinding wheels. Generally, the particle size is 80～120# when sharpening carbide teeth, and the hardness of the grinding wheel is intermediate. The concentration of diamond grinding wheel refers to the mass of diamond contained per unit volume in the material layer. The standard is 0.879g (4.39 carats)/cm3, and the concentration is 100%. The concentration of 50% or 100% is generally used when sharpening carbide serrations. Table 1 shows the shape and code of commonly used diamond grinding wheels. There are four types of bonding agents for diamond grinding wheels: bronze (Q), resin (S), ceramic (A) and electroplating (D). The resin bond diamond wheel is generally used for dry grinding, and the bronze bond diamond wheel for wet grinding with coolant.
The marking sequence of diamond grinding wheel is: abrasive-particle size-hardness-bond-concentration-shape-size. The size injection method is: outer diameter×thickness×aperture×diamond material ring width×material layer thickness×angle. For example, the abrasive is a diamond grinding wheel with synthetic diamond, particle size 100#, medium hardness, resin bond, concentration 50%, disc-shaped grinding wheel, outer diameter 80mm, thickness 13mm, aperture 20mm, material ring width 3mm, material layer thickness 3mm The mark is: JR100#Z50D180×13×20×3×3.
Before using the grinding wheel, check whether the grinding wheel has no gaps, concentricity, vibration, etc. and whether the surface is clean. When using a diamond grinding wheel to sharpen a carbide saw blade, it should not be in contact with the saw blade body of tool steel material, otherwise the grinding wheel will be blocked. The saw blade body of tool steel material should be ground with corundum or silicon carbide abrasive wheels.
Because of the high hardness of cemented carbide, greater grinding pressure is required during sharpening, and because of its low thermal conductivity, it is not allowed to generate excessive heat. Therefore, it is required to have good cooling and heat dissipation conditions during sharpening, which is usually required. Coolant to reduce the occurrence of grinding cracks. When using a diamond grinding wheel to sharpen cemented carbide saw teeth, the total grinding amount should be controlled below 0.1mm. If the grinding amount is too large, the diamond consumption of the grinding wheel is too high and the cost is too high. For sharpening YG6 and YG8 cemented carbide serrations, when the coolant supply is within the range of 3~4L/min, the grinding wheel with bronze bond, particle size 100~120# and concentration 100% can be used.