Sstudy Of Plasmaarc-Asssisted Cutting Granite

At present cutting processing by diamond saw blade is widely used in graniteindustry, however, the blade is prone to wear and diamond of blade is easy to falloff. So it is urgent to reduce cutting force, extend tool life and improve efficiencyof processing. In response to this problem, heating assisted cutting granite by thehigh energy plasma arc is studied through experiments and analog simulation.The jet profile and temperature field distribution are displayed in differentparameters by setting up image acquisition system of heating assisted plasma jet byCCD camera and then processing the image by use of Matlab numerical analysissoftware. Image results show that: working current and voltage larger, energy greater;smaller plasma gun nozzle aperture leads to more intense compression plasma arc andgreater energy density, which is propitious to heat the workpiece. Based on the heattransfer theory, temperature and stress profiles in granite are analyzed by establishingthe finite element model of unidirectional and reciprocating plasma arc thermalloading on granite. With the movement of plasma arc, temperature diffuses from hotspot to all directions in granite, hence periodic waves of thermal stress are generatedin the granite.By means of the thermal shock and uniaxial compression experiment, we obtainthe laws of granite mechanical properties change with temperature. The rise oftemperature makes the elastic modulus and compressive strength decline and thestrain increase. The thermogravimetry–differential scanning calorimetry analysis ofgranite indicates that physical and chemical react in microstructure of rock such asdehydration, oxidation and crystallization under thermal load, which brings rockthermal damages and induces crack growing and expanding, and cause the macromechanical properties changes. Experimental device of plasma arc assisted cuttinggranite is established and wear characteristics of diamond saw blade are investigatedby the experiment of cutting. The results show that the smaller suspension distanceand the lower scanning speed of plasma are, the smaller blade wear is. When the temperature is350℃, wearing capacity was reduced80%. It confirms that the heatingcharacteristics of the plasma arc has a remarkable effect in reducing wear of the tool.This paper presents a method that cutting granite by plasma arc assisted, whichsignificantly reduces tool wear, processing costs and improves processing efficiency.The results provide a strong technical support for processing hard and brittle materialssuch as stone machining and further industrial applications.