The research of integrality of surface of milling of high speed of titanium alloy TC4

4 × 103, than intensity Sb/g=23.

5, and of alloy steel be less than than intensity Sb/g 18. Titanium alloy thermal conductance is low. The thermal conductance of titanium alloy is the 1/5 of iron, aluminous 1/10, the thermal conductance L=7 of TC4.

955W/m · K. The stretch model quantity of titanium alloy is inferior. The stretch model of TC4 measures E=110GPa, it is the 1/2 of steel about, when reason titanium alloy is machined, easy generation is out of shape. The dimension of test specimen of condition of exterior integrality experiment of milling of 2 high speed: 200 × of 420 × 24mm. Milling machine: X5040 vertical milling machine. Cutting tool: Helix of Y330 hard alloy establishs milling cutter, 4 tine. Milling means: Arrange mill, zhou Xi. Milling parameter: Ap=10mm, ae=0.

2mm, vf=100mm/min, ) of parameter of N=500r/min(groovy milling; Ap=10mm, ae=0.

2mm, vf=500mm/min, n=2, ) of milling of 500r/min(high speed. Of milling surface integrality detect the grain below milling surface is crooked the deepness that twist a layer detects the test specimen sampling that falls to different milling parameter above all, an aleatoric profile that cuts the surface from perpendicular Yu Xi is abrade with polishing, corrode to its polish surface next, can arrive in the observation below metallographic microscope below milling surface grain is crooked roll rate. When choosing A parameter, the meeting below the surface layer when titanium alloy material is machined produces more apparent grain twist phenomenon, the crooked deepness that twist a layer amounts to grain 7µm; And when choosing B parameter, grain is crooked twist not apparent, the crooked deepness that twist a layer is less than grain 1µm. This makes clear high speed milling to be out of shape to twist of titanium alloy grain dinky, it is to solve structural member of thin wall of titanium alloy whole to machine metabolic ideal to machine a method, also be to obtain little or those who do not have degenerative layer surface is reliable method. Stress of milling surface remains reachs his to distributing condition of strength of correspondence of titanium alloy material is very sensitive, the leftover stress that machines the surface especially reachs his to distributing condition is right component part whether can reasonable using is very important. The leftover stress that already machined the surface has remains to pull what stress and remains press stress to fasten, remains pulls stress to be able to lower the fatigue intensity of the spare parts and service life, and the fatigue intensity that remains presses stress to be able to raise a part however sometimes and service life. Treatment surface is departmental divide leftover stress distributing inhomogenous, also can make workpiece generation is out of shape, affect the appearance of workpiece and dimension precision. Accordingly, stress of urgent need understanding and remains of surface of milling of high speed of material of TC4 of research titanium alloy reachs his to distributing. Graph the distributinging graph of stress of remains of layer of surface of milling of 1 low speed the distributings to measure surface of titanium alloy milling with X ray law leftover stress of stress of remains of layer of surface of milling of 2 high speed. Stress of remains of layer of surface of low speed milling reachs his to distributing see a picture 1; Stress of remains of layer of surface of high speed milling reachs his to distributing see a picture 2. Can see from inside the graph, when low speed milling, exterior remains presses stress bigger, and inside edge surface layer pull stress to distributing gradient is bigger also, after causing material to machine so be out of shape very big, and spare parts in use can arise because of the attenuation of stress bigger be out of shape, cause a spare parts to cannot be used normally. To surface of high speed milling, exterior remains stress wants relatively small, and exterior internal stress distributings gradient is small, change of the stress when the spare parts is used is slow, the part that causes is out of shape small also much. Make clear from this, high speed processing technique is thin wall structural member the reliable method of efficient treatment. Of milling sclerosis layer detect when milling chooses A parameter, below dry cutting condition, the distributinging deepness of layer of milling case hardening and microscopical the relation of hardness is shown 1 times like the watch; When milling uses B parameter, below dry cutting condition, the distributinging deepness of layer of milling case hardening and microscopical the relation of hardness is shown 2 times like the watch. Express 1, 2 make clear, what milling of high speed of titanium alloy material compares face of low speed milling is microscopical hardness is low much, with the graph 1, the result photograph be identical of 2, apparently grain produces milling of demonstrative high speed misrepresentation is out of shape lesser, cold make sclerotic pitch very small also, and cold the deepness that makes sclerotic layer is very shallow. The disagreement that proved material of titanium alloy TC4 to issue treatment in rate of commonly used milling through the test of sclerotic layer deepness is rational. To raise the utilization rate of numerical control machine tool and improvement titanium alloy machines exterior quality, should choose the treatment of higher rate, especially wainscot of large to titanium alloy whole and integral frame, technology of high speed milling has the advantage that other treatment method cannot compare. Express layer of case hardening of milling of 1 low speed to distributing deepness and microscopical the relation deepness 0 2 of hardness.

5 5 7.

5 10 12.

5 15 17.

5 microscopical hardness 383 365 350 342 330 312 312 312 expresses layer of case hardening of milling of 2 high speed to distributing deepness and microscopical the relation deepness 0 1 1 of hardness.

5 2 3 4 is microscopical of surface roughness of surface of milling of hardness 340 320 312 312 312 312 detect the treatment outside that appearance leaves to different milling rate undertakes surface roughness of use GJD-5E surface test, the exterior surface roughness when milling chooses A parameter is Ra6.

4µm, and when milling chooses B parameter, exterior surface roughness is Ra0.

8µm. Apparent, the value wants the exterior surface roughness below milling of low speed of high speed ratio a lot of lower. The research that 3 last words carry integrality of pair of surface of milling of titanium alloy high speed can reach the following conclusion: Processing technique of high speed milling is led to raising titanium alloy to machine effect and improving the surface to machine quality is very effective. Use method of high speed milling, rate of relatively commonly used milling can make machine efficiency to raise 5 times, make the value reduces exterior surface roughness substantially. Use method of high speed milling to process titanium alloy data, what the remains that the surface forms presses stress to compare rate of commonly used milling is low, and the leftover stress gradient that forms below surface layer is small, stress distributings more reasonable. Especially the biggest pull stress to want small much, in pull stress area stress change is gently, because this structural member suffers after force, stress attenuation also is met smoother, component part arises be out of shape small, this is advantageous to bear the weight of and be being used of the spare parts. Use high speed milling to machine titanium alloy TC4, surface layer metal is fashioning the process that already machined the surface in, the plasticity that happen is out of shape small, of grain crooked roll rate small, in be located in paper-thin surface layer consequently cold make sclerosis intense, of the organization microscopical hardness is taller also, and edge surface a bit to in outspread, sclerotic degree can be reduced apparently. Use method of high speed milling to machine titanium alloy, can obtain grinding to machine the exterior mass that the method can reach directly, namely surface roughness of low stress, low surface is worth and lesser cold make sclerotic layer deepness. CNC Milling