The experiment of force of grinding of alloy of titanium of microtherm ELID grinding studies

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One, when introductive nicety and alloy of titanium of half accurate grinding, because the material character of titanium alloy caused its grinding difficulty. This basically is the reason of the following respects: (1) titanium and heat conduction of titanium alloy material, coefficient of temperature conductivity is small, it is the 1/15 of aluminium and aluminium alloy thermal conductance only, the 1/5 of steel thermal conductance. Low heat conduction, in guiding lukewarm rate makes its are machined in grinding, grinding heat sends out not easily, return meeting generation to machine felt phenomenon. (2) titanium and titanium alloy are chemical when high temperature active is tall, because grinding temperature is high, worry bit easily the element such as the oxygen in air, nitrogen produces chemical reaction to form, those who accelerate emery wheel wear away. Coefficient of friction is big, stretch model amount is small, succumb intensity comparing is big, this kind of characteristic meeting makes machine spare parts surface to produce bigger spring back to be out of shape, cause grinding muscularity thereby, affect treatment precision. Because titanium alloy has chemical active tall, stick, the characteristic such as pliable but strong, add the grinding that wear bead to choose local high temperature and pressure action, grind bead and metallic surface to be able to produce physical sex felt because of affinity. The conglutinate problem in process of titanium alloy grinding will make emery wheel accelerates loss, affect the treatment surface quality of workpiece, and the size that created force of titanium alloy grinding depends on not only the power that cutting workpiece material produces, and depend on the power that conglutinate obliterates the titanium alloy material on bead and workpiece surface to contact generation each other to the job. Be opposite in the light of above titanium alloy nicety and problem of the existence in half accurate grinding, use liquid nitrogen to serve as cooling medium, drop the grinding temperature of titanium alloy, change its material character, reduce titanium alloy the conglutinate phenomenon in grinding process, follow the respect such as the metabolic trend of grinding deepness and mechanism of titanium alloy grinding from grinding force, studied the microtherm effect to titanium alloy grinding. Fracture surface of ℃ concussion of C)-196 of fracture surface of concussion of ℃ of B)-40 of mouth of A)18 ℃ strong strike off pursues alloy of the titanium below 1 different temperature pounds fracture surface appearance of microcosmic surface form 2, titanium alloy (of function of TC4) low temperature, had test of function of titanium alloy low temperature. Experimental result makes clear, reduce as temperature, the hardness of titanium alloy and brittleness increase, concussion tenacity is reduced. Graph the 1 concussion fracture surface that issues titanium alloy for different temperature is microcosmic photograph of exterior form appearance. Fall by room temperature when temperature to liquid nitrogen temperature (- 196 ℃ ) when, its rupture exterior form appearance is transformed to fracture surface of brittleness cleavage shape by fracture surface of shape of nest of plasticity pliable but strong. From this knowable, if make grinding is in microtherm condition, can make the plasticity of titanium alloy is reduced, increase its brittleness, make its agree with thereby grinding. 3, if the methodological principle that device of microtherm grinding experiment and experimental condition experiment use pursues 2 are shown. Test specimen installs clip to measure power instrument to go up to piezocrystal in KISTLER3, liquid nitrogen nozzle liquid nitrogen direct eject enters grinding area. From this, the change of amplifier of signal classics charge of the force of the generation in grinding process is the voltage signal of enlarge, collect signal of calorie of word of change amount to to input the computer via A/D data next, the data that collects to place finally undertakes the computer is handled, the Fn of law Xiang Li that produces in process of titanium alloy grinding basically is measured in this experiment and tangential force Ft. Graph grinder of condition of experiment of principle of device of experiment of alloy of titanium of grinding of 2 low temperature: Emery wheel of grinder of MM7120A accurate plane: W10 iron base emery wheel of bond CBN emery wheel is the largest linear velocity: Vs=14m/s feed speed: Vw=5.

8m/min grinding craft: Dry grind, in process of experiment of grinding of low temperature of refrigeration of sparge of liquid nitrogen of union of ELID grinding, ELID, use two kinds of different grinding technique, the grinding force Fn that arises to the place in process of titanium alloy grinding, Ft undertakes metrical, w10 iron base bond CBN emery wheel uses plastic of electric spark method, apply ELID technology to undertake online electroanalysis build fighting spirit beforehand. Fall through comparing condition of craft of two kinds of different grinding, force of titanium alloy grinding follows the trend that grinding deepness changes and size, and grind workpiece surface to undertake microcosmic form appearance is analysed to the place below condition of different grinding craft, can see the microtherm effect to titanium alloy grinding, conclude a titanium alloy conglutinate below condition of different grinding craft, judge the grinding effect of alloy of microtherm grinding titanium accordingly. 4, experimental result and analysis pursue curve of the 3 grinding force Fn that measure to be below condition of different grinding craft, Ft and grinding deepness change. By can see in the graph, alloy of ELID grinding titanium is used to be able to reduce filing effectively below microtherm condition Xiang Li Fn and tangential force Fn, its reason is: Graph the course that force of the grinding below condition of 3 different technology follows the metabolic curve of grinding deepness to wear bead cutting stuff can be divided roughly be out of shape for flexibility, plasticity is out of shape reach cut bits to form 3 phase, fall in microtherm condition so, because the hardness of titanium alloy and cold brittleness increase somewhat, and configuration of its fracture surface has Cong Ren nest shape manages to solution the gender is fragile break changed trend, from this, below microtherm condition, those who grind bead and workpiece is slippery brush reduce with plough process, the grinding force; that reduced titanium alloy thereby falls in microtherm condition, can drop the temperature of grinding area significantly, the requirement that makes phenomenon of titanium alloy conglutinate arises so is like local high temperature to wait not answer existence, because this grinds the affinity of bead and metallic surface to reduce, won't produce content reason felt with emery wheel, conglutinate rate is reduced, grinding force is reduced; Employ alloy of titanium of groovy method grinding, because titanium is lively tantalum, and grinding area temperature is high, cause titanium alloy thereby fresh grinding surface is in atmosphere with oxygen action, oxygen diffuses in titanium alloy surface layer, create layer of so called pollution. Oxygen enlarge thes meeting is over be being ground apparently the oxide TiO2 that forms titanium, Ti2O3 or oxygen the solid solution in A-Ti. Oxygen diffuses after titanium alloy surface layer, cause titanium alloy the hardness of scanty surface layer and intensity increase, plasticity drops, its make grinding force increases as a result, of aggravate emery wheel wear away. And use device of grinding of eject type low temperature, can make grinding is in gas of sex of the Sui Dynasty to protect next undertaking, prevented the defect of afore-mentioned groovy grinding so, make grinding force is reduced thereby, the grinding quality of workpiece surface raises; to combine line nap below microtherm condition (ELID) grinding technology can maintain those who wear bead for long sex of sharp edge acute, add the space holding bit of emery wheel, avoid emery wheel to jam, the grinding force of titanium alloy also can be reduced for the respect from now on. 5, alloy of titanium of grinding of ELID of low temperature of type of sparge of conclusion liquid nitrogen can drop force of titanium alloy grinding and grinding area temperature effectively, make conglutinate of alloy of titanium of emery wheel surface is reduced apparently thereby. Use device of grinding of sparge type low temperature to make titanium alloy grinding is in inert gase to protect atmosphere, reduced pollution of titanium alloy surface layer. Replace fluid of titanium alloy grinding with liquid nitrogen, do not have pollution and harm to circumjacent environment and handlers, be helpful for realizing green to make. CNC Milling