What are the factors that affect the life of diamond saw blades?
Factors affecting the efficiency and life of the diamond circular saw blade are the sawing process parameters and the particle size, concentration, and bond hardness of the diamond. According to the cutting energy, there are saw blade line speed, sawing concentration and feed speed.
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First, the sawing parameters
(1) Saw blade line speed: In actual work, the linear speed of the diamond circular saw blade is limited by the condition of the equipment, the quality of the saw blade and the nature of the sawed stone. From the optimum saw blade life and sawing efficiency, the linear speed of the saw blade should be selected according to the nature of the different stones. When sawing granite, the linear speed of the saw blade can be selected from 25m to 35m/s. For granite with high quartz content and difficult to saw, the lower limit of the blade line speed is appropriate. In the production of granite tiles, the diameter of the diamond circular saw blade is small and the line speed can reach 35m/s.
(2) Sawing depth: The sawing depth is an important parameter related to diamond wear, effective sawing, blade force and the nature of the stone being sawed. Generally speaking, when the linear speed of the diamond circular saw blade is high, a small cutting depth should be selected. From the current technology, the depth of the sawing diamond can be selected between 1 mm and 10 mm. When sawing granite blocks with large-diameter saw blades, the sawing depth can be controlled between 1mm and 2mm, and at the same time, the feed rate should be reduced. When the linear speed of the diamond circular saw blade is large, a large depth of cut should be selected. However, when the performance of the saw and the allowable range of tool strength, the cutting concentration should be taken as much as possible to improve the cutting efficiency. When there is a requirement for the machined surface, a small depth cut should be used.
(3) Feeding speed: The feed speed is the feed rate of the sawed stone. Its size affects the sawing rate, the force on the saw blade, and the heat dissipation in the sawing area. Its value should be selected according to the nature of the stone being sawed. Generally speaking, sawing softer stone, such as marble, can increase the feed speed appropriately. If the feed speed is too low, it is more conducive to improving the sawing rate. The sawing of fine-grained, relatively homogeneous granite can increase the feed speed appropriately. If the feed speed is too low, the diamond edge is easily smoothed. However, when sawing a coarse-grained structure with uneven hardness, the feed speed should be reduced. Otherwise, the saw blade vibrates and the diamond is broken and the sawing rate is lowered. The cutting speed of sawn granite is generally selected within the range of 9m to 12m/min.
Second, other influencing factors
(1) Diamond particle size: The commonly used diamond particle size is in the range of 30/35 to 60/80. The harder the rock, the finer particle size should be chosen. Because under the same pressure conditions, the diamond is finer and sharper, which is good for cutting into hard rock. In addition, generally large-diameter saw blades require high sawing efficiency, and coarser granularity should be selected, such as 30/40, 40/50; small-diameter saw blade sawing is inefficient, requiring rock sawing section to be smooth, suitable Choose a finer particle size, such as 50/60, 60/80.
(2) Tool head concentration: The so-called diamond concentration refers to the density of diamond distributed in the working layer carcass (ie the weight of diamond contained in a unit area). The “Specifications” stipulate that the concentration of 4.4 carats of diamond per cubic centimeter of working carcass is 100%, and the concentration of diamond containing 3.3 carats is 75%. The volume concentration indicates the volume of diamond in the agglomerate, and specifies that the concentration of the diamond is 100% when it 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 concentration reduces the average cutting force per diamond. However, increasing the depth necessarily increases the cost of the saw blade, so there is a most economical concentration, and this concentration increases as the cutting rate increases.
(3) Hardness of the cutter bond: Generally, the higher the hardness of the bond, the stronger the wear resistance. Therefore, when sawing a rock with high abrasiveness, the hardness of the bonding agent should be high; when sawing a soft rock, the hardness of the bonding agent should be low; when sawing a hard and hard rock, the hardness of the bonding agent should be moderate. .
(4) Force effect, temperature effect and wear and tear: Diamond circular saw blade will be subjected to alternating load such as centrifugal force, sawing force and sawing heat during the process of cutting stone.
The wear and tear of the diamond circular saw blade is caused by the force effect and the temperature effect.
Force effect: During the sawing process, the saw blade is subjected to axial and tangential forces. Due to the force acting in the circumferential direction and the radial direction, the saw blade is wavy in the axial direction and is dished in the radial direction. Both of these deformations will result in uneven rock surface, high waste of stone, high noise during sawing, and increased vibration, resulting in early damage of diamond agglomerates and reduced saw blade life.
Temperature effect: The traditional theory holds that the effect of temperature on the saw blade process is mainly manifested in two aspects: one is to cause graphitization of diamond in the agglomerate; the other is to cause the thermal force of the diamond and the carcass to cause the diamond particles to fall off prematurely. . New research shows that the heat generated during the cutting process is mainly agglomerated. The arc temperature is not high, generally between 40 and 120 °C. The grinding point temperature is higher, generally between 250 and 700 °C. The coolant only reduces the average temperature of the arc zone, but has little effect on the abrasive grain temperature. Such a temperature does not cause carbonization of the graphite, but changes the frictional properties between the abrasive particles and the workpiece, and causes thermal stress between the diamond and the additive, resulting in a fundamental bending of the diamond failure mechanism. Studies have shown that the temperature effect is the biggest factor affecting the breakage of the saw blade.
Wear and tear: Due to the force effect and temperature, the saw blade will often wear and tear after a period of use. There are mainly the following types of wear and tear: abrasive wear, partial crushing, large-area crushing, shedding, mechanical abrasion of the binder along the sawing speed direction. Abrasive wear: Diamond particles and the piece continue to rub, the edges are passivated into a plane, losing cutting performance and increasing friction. The sawing heat will cause a graphitized thin layer on the surface of the diamond particles, which greatly reduces the hardness and aggravates the wear: the surface of the diamond particles is subjected to alternating thermal stress, and at the same time, it undergoes alternating cutting stress, and fatigue cracks occur and partial breakage occurs. A sharp new edge is an ideal wear pattern; large area fracture: diamond particles are subjected to impact load when cut in and out, and relatively prominent particles and grains are consumed prematurely; shedding: alternating cutting force makes diamond The particles are constantly shaken in the binder to cause loosening. At the same time, the wear and sawing heat of the bonding agent itself during the sawing process softens the bonding agent. This causes the holding force of the bonding agent to decrease, and when the cutting force on the particles is greater than the holding force, the diamond particles fall off. Whichever type of wear is closely related to the load and temperature to which the diamond particles are subjected. Both of these depend on the cutting process and the cooling lubrication conditions.