高速立铣ti-6al-4v合金的刀具磨损和切削力变化英文-外文文献(编辑修改稿)

高速立铣ti-6al-4v合金的刀具磨损和切削力变化英文-外文文献(编辑修改稿)内容摘要：

iodical fluctuation of cutting forcescaused by the chip thickness variations and the periodicalentry/exit of the cutting teeth is an essential feature ofmilling process.3 Results and discussions Highspeed milling experiment Experimental setupAn annealed alphabeta titanium alloy, Ti6Al4V, wasselected as a workpiece material and the chemical position and mechanical properties of the material are shownin Tables 1 and 2, respectively. The workpiece materialthroughout the experimental work was prepared in the formof 12010020 mm rectangular block. Four holes weredrilled into the block for attaching to the KISTLER forcedynamometer with screws. Before beginning endmillingtests, the blocks were facemilled to remove any surfacedefects.The cutting tool used in the endmilling tests was an endmill of 25 mm diameter. The end mill can be equipped withtwo micrograin straight cemented tungsten carbide inserts(Seco H25 grade). However, in this study, only one insertper experiment was mounted on the cutter to avoid theinfluence of the tooltip runout on tool wear analysis.Geometric bination of the insert and the tool bodyresulted in 5176。 rake angle, 5176。 axial rake angle, and −2176。 radialrake angle.All the endmilling tests were performed on a CNCvertical machining center. The specimen was mounted onthe top of KISTLER force dynamometer, which was fixedon the machine table as shown in Fig. 3. Experimental procedureThe cutting tests were carried out in down milling processwith a cutting speed vc=100 m/min (spindle rotation speedn=1,274 r/min), a feed rate fz= mm/tooth, an axial depthof cut ap= mm and a radial depth of cut ae=5 mm. Thefeed direction of the workpiece was along the negative xaxis as shown in Fig. 3 and the workpiece length in the feeddirection was 100 mm (. the width of the workpiece).Dry cutting without any cutting fluids was used for themilling tests.A dynamometer (Kistler type 9257A) mainly consists ofthreeponent force sensors fitted under high preloadbetween a base plate and a top plate. Each sensor containsthree pairs of quartz plates, one sensitive to pressure in thezdirection and the other two responding to shear in the xand ydirections, respectively. Three coaxial cables wereconnected to the charge amplifier (Kistler type 5007) of theforce platform and then the output voltage signals were fedinto a highresolution–highfrequency A/D data acquisitionboard (CRAS Type AZ802) and the signals were recordedat a sampling frequency of 24 kHz. During highspeed endmilling tests, the instantaneous cutting force ponents inx, y, and zdirections, Fx, Fy, and Fzwere recorded downthrough CRAS data acquisition/analysis software.According to Eq. 6, the cutting length of each pass wasapproximate 120 mm. Then, highspeed endmilling testwas interrupted at regular interval of three cutting passes(approximate 3 min) to measure and study the evolution ofTable 2 Mechanical properties of Ti6Al4V alloy at room temperatureDensity [kg/m3] Young’s modulus [GPa] Yield strength [MPa] Hardness [HB] Elongation [%] Reduction in area [%]4,430 880 334 14 36Table 1 Chemical positions of Ti6Al4V alloy (wt. %)Al V Fe Si C N H O Titanium Balance72 Int J Adv Manuf Technol (2020) 46:69–78the tool wear. The tool wear of the cutting edge wasevaluated under scanning electron microscope (SEM) withenergy dispersive xray spectroscopy (EDS). In addition,the chips collected from highspeed endmilling tests wereanalyzed by using the same SEM/EDS system. Results and discussions Tool wearThe milling operation is a classical intermitted cuttingprocess, in which the cutting edges may experiencefluctuating cutting forces and heat with the entry/exit ofthe cutting tooth. The low thermal conductivity of Ti6Al4V alloy causes the high cutting temperature at the tool–chip contact zone close to the cutting edge. What is moreimportant is that Ti6Al4V alloy has high chemicalreactivity with most of tool materials at high temperature.Moreover, at high temperature and high contact stresses, thetitanium chip maintains a very intimate contact with thetool on the tool rake surface and flank surface [9, 10]through an interfacial layer. Therefore, tool wear in cuttingtitanium alloys is much more intense due to hightemperature and contact stresses at the tool–chip interface.A characteristic wear pattern on cemented tungstencarbide tools is the “crater” that forms on the rake surface(a) After 3 minutes of milling Crater Adhering chip Crater Abrasion Adhering chip (b) After 12 minutes of milling100181。 m 100181。 mFig. 4 SEM views of crater wear on rake surface a after 3 min of milling。 b after 12 min of millingCNCHighspeed machining centerSpindleEnd millWorkpieceDynamometerMachine tableyxozToolholderCharge amplifierData acquisitionboardSignal analyzer softwareFig. 3 Experimental setupInt J Adv Manuf Technol (2020) 46:69–78 73of the cutting tool at a short distance from the cutting edgeduring highspeed endmilling of Ti6Al4Valloy as shownin Fig. 4a, b. It is worth noting that, all the width of thecrater wear was narrow unlike the crater wear in case ofcutting of steels which starts at a little distance away fromthe cutting edge [5]. The narrow crater width could beattributed to the short tool–chip contact length inherent tocutting of titanium and the high cutting temperatureconcentrated at a narrow region adjacent to the cuttingedge.During highspeed endmilling Ti6Al4Valloy, the highlocal temperature at the tool–chip interface and theconcentration gradient of chemical constituents betweenthe cutting tool and the workpiece materials simultaneouslysupport two types of diffusion at the tool–chip interface tosome extent, ., diffusion of cutting tool constitue。