The factors that affect the efficiency and service life of diamond circular saw blades include sawing process parameters, diamond particle size, concentration, binder hardness, etc. According to the cutting energy, there are saw blade linear speed, sawing concentration and feed speed.
I. Sawing parameters.
(1) Saw blade linear speed: In actual work, the linear speed of diamond circular saw blades is limited by equipment conditions, saw blade quality and sawing stone properties. In order to achieve the best service life and sawing efficiency of the saw blade, the saw blade linear speed should be selected according to the properties of different stones. When sawing granite, the saw blade linear speed can be selected in the range of 25m ~ 35m/s. For granite with high content of quartz and difficult to cut, it is recommended to take the limit of the saw blade linear speed. In the production of granite tiles, the diameter of the diamond circular saw blade is small and the linear speed can reach 35m/s.
(2) Sawing depth: The sawing depth is an important parameter related to diamond wear, effective sawing, saw blade stress and sawing stone performance. Generally speaking, when the linear speed of the diamond circular saw blade is high, a smaller cutting depth should be selected. From the current technology, the cutting depth of diamond can be selected between 1 mm and 10 mm. Usually, when sawing granite waste with a large diameter saw blade, the sawing depth can be controlled between 1mm-2mm, and the feed speed should be reduced. When the linear speed of the diamond circular saw blade is high, the cutting depth should be selected. However, within the allowable range of sawing machine performance and tool strength, it is necessary to try to adopt a larger cutting concentration to improve cutting efficiency. When it is necessary to process the surface, a small depth of cutting should be used.
(3) Feed speed: The feed speed is the feed speed for sawing stone. Its size affects the sawing rate, saw blade stress and heat dissipation in the sawing area. Its value should be selected according to the properties of the sawed stone. Generally speaking, when sawing soft stone, such as marble, the feed speed can be appropriately increased. If the feed speed is too low, it will be more conducive to improving the sawing rate. When sawing granite with fine-grained uniform structure, the feed speed can be appropriately increased. If the feed speed is too low, the diamond edge is easily worn flat. However, when sawing granite with coarse grain structure and uneven hardness, the feed speed should be reduced, otherwise the vibration of the saw blade will cause the diamond to break and the sawing rate will be reduced. The feed speed for sawing granite is generally selected in the range of 9m ~ 12m/min.
Second, other influencing factors.
(1) Diamond particle size: The commonly used diamond particle size range is 30/35 ~ 60/80. The harder the rock, the finer the particle size should be selected. Because under the same pressure, the finer the diamond, the sharper it is, which is conducive to cutting into hard rock. In addition, generally large-diameter saw blades have higher requirements for sawing efficiency, and coarse particles such as 30/40 and 40/50 should be selected; small-diameter saw blades have low sawing efficiency and require a smooth sawing surface. Fine grain size should be selected, such as 50/60 and 60/80. (2) Head concentration: The so-called diamond concentration refers to the density of diamond distribution in the working layer matrix (that is, the weight of diamond contained per unit area). According to the Code, when the working matrix contains 4.4 carats of diamonds, its concentration is 100%, and when it contains 3.3 carats of diamonds, its concentration is 75%. Volume refers to the volume of diamonds in the agglomerate, and it is stipulated that the concentration is 100% when the diamond volume accounts for 1/4 of the total volume. Increasing the diamond concentration is expected to extend the life of the saw blade because increasing the diamond concentration will reduce the average cutting force per diamond. However, increasing the depth will inevitably increase the cost of the saw blade, so there is an optimal concentration that increases with the increase in cutting rate.
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(3) Hardness of the Diamond Cutting blade binder: Generally speaking, the higher the hardness of the binder, the stronger its wear resistance. Therefore, when sawing highly abrasive rocks, the hardness of the binder should be very high. When sawing soft rocks, the hardness of the binder should be low. When sawing abrasive and hard rocks, the hardness of the binder should be moderate.
(4) Force effect, temperature effect and wear damage: During the stone cutting process, the diamond circular saw blade will be subjected to alternating loads such as centrifugal force, sawing force and sawing heat.
The wear of diamond circular saw blades by force effect and temperature effect.
Force: During sawing, the saw blade is subjected to axial force and tangential force. Due to the forces in the circumferential direction and radial direction, the saw blade is wavy in the axial direction and disc-shaped in the radial direction. Both deformations will cause uneven rock sections, waste of stone, loud noise during sawing, and increased vibration, which will lead to early destruction of diamond agglomerates and shorten the service life of the saw blade.
The influence of temperature: According to traditional theory, the influence of temperature on saw blade processing is mainly manifested in two aspects: first, it causes graphitization of diamonds during agglomeration; second, the thermal interaction between diamonds and the matrix causes diamond particles to fall off prematurely. New research shows that the heat generated during cutting is mainly transferred to agglomerates. The temperature in the arc zone is not high, generally between 40 and 120. But the grinding point temperature of the abrasive is relatively high, generally between 250 and 700. However, the coolant only reduces the average temperature in the arc zone, but has little effect on the abrasive temperature. This temperature does not carbonize graphite, but changes the friction between the abrasive and the workpiece, causing thermal stress between the diamond and the additive, resulting in a fundamental bending of the diamond damage mechanism. Studies have shown that the temperature effect is the biggest factor affecting the fracture of the saw blade.
Wear damage: Due to the force effect and the influence of temperature, the diamond saw blade will often wear after a period of use. The main forms of grinding damage are: abrasive wear, local breakage, large-area breakage, shedding, and mechanical scratches of the binder along the sawing speed. Abrasive wear: Diamond particles are constantly rubbing against the workpiece, and the edges are passivated into a plane, losing cutting performance and increasing friction. The heat of sawing will cause a thin layer of graphitization on the surface of the diamond particles, greatly reducing the hardness and aggravating wear. When the surface of the diamond particles is subjected to alternating thermal stress and alternating cutting stress, fatigue cracks will appear and local fractures will appear, presenting a sharp new edge, which is an ideal form of wear. Large-area crushing: Diamond particles are subjected to impact loads when cutting in and out, and protruding particles and grains are consumed prematurely; peeling: The alternating cutting force causes the diamond particles to shake continuously in the binder, resulting in loosening. At the same time, the wear of the binder itself and the heat of sawing soften the binder. This reduces the holding force of the binder, and when the cutting force on the particle is greater than the holding force, the diamond particles will fall off. Both types of wear are closely related to the load and temperature of the diamond particles. Both depend on the cutting process as well as the cooling and lubrication conditions.
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