Mathematical Model and Simulation of Cutting Force in Plunge Milling Process

Transactions of Tianjin UniversityISSN1006-4982pp303-307Vol.13 No.4Aug.2007Mathematical Model and Simulation of Cutting Force inPlunge Milling ProcessQIN Xuda(秦旭达) , ZHAO Jianbo(赵剑波)'，LIU Huanling(刘焕领)' , ZHANC Jiangang(张剑刚)' ,ZHAO Wei(赵伟) , TIAN Ying(田颖)', TOM 0 Mulle2，NI Wangyang' , IU Yixiong2(1. School of Mechanical Engineering, Tanjin University, Tanjin 300072, China;2. Kennanelal lnc. Latrobe, PA 15650, USA)Abstract: Plunge milling is a high-speed machining way and the cutter is fed in the direction of the Zaxis, which is used to remove excess material rapidly in roughing operations. In this paper, the or-thogonal cutting theory was used to study the plunge milling of LY12 alloy. A mathematic model forcutting force in plunge milling was established, and the milling process was simulated by using Mat-lab. It is found that the single tooth cutting experimental result is unstable because of unsymmetricalsingle tooth in the milling process, which leads to the difference between the simulation and experi-mental results. The trend of multiple teeth cutting experimental result is similar to that of the simula-tion result; however, the peak values in the experimental result are different, which is caused by theerror of cuttr's position, and the error of peak value is less than 10%.Keywords: plunge milling; cutting force; aluminium alloys; simulationPlunge milling, also called Z-axis milling, is one ofthe most efective machining methods in high speed metal4removal machining. As for curved surface of difcult-to-ma-chine material, slot-cut working and machining with longercutter of suspending length, the machining eficiency is bet-ter than that of the end milling method. As shown in Fig.1,the major diference between plunge milling and traditionalmilling is that the former can reduce the machining time byhalf. Furthemmore, it can also minimize distortion of work-Fg.1 Milling fore sketchpiece, reduce the radial cutting force acting on the millingmachine, prolong the overhang length, and slot-cut in thehigh temperature alloy material. When a high metal removal and quality of turbine blade millingl, And it was used inrate is desired or when machining aviation part with complex machining major diameter deep flow channel of two dimen-geometry, plunge milling will be considered first. Com- sional impeller'2J. Plunge milling was also used in roughpared with the end milling, plunge milling has the advan- machining blisk, and the machining ficiency and the vi-tages of high machining fficiency, short machining time，bration phenomenon could be improved obviouslyl31. Theand a good applicabilty in various machining circumstanc- model of milling fore in plunge milling was completedl4s1.es. It is suitable for the machining of prototype parts of The instantaneous cutting force cofficients to build plungesmall batch and the manufacturing of mass batch parts.milling force model6l, and the dynamics and stability ofIn China, plunge milling was used in turbine blade plunge milling operations were also raisedl7J .numerical control (NC) milling to improve the efficiencyTheoretical research on LY12 alloy, especially on theAcepted date:2007-03-16.QIN Xuda, born in 1973, male, Dr, asociate Prof.中国煤化工Tanjin UnivesityKen-# Supported by Advanced Manufacturing Technology-Kcy Laborntory of Beijingmetal Joint Project, Young 'Teacher Foundation of Tanjin Uaiversity, Appara:MYHCNMHGCorrespondence to ZHAO Jianbo, E mail:joetju@ 126. com.Transactions of Tianjin UniersityVol.13 No.4 2007simulation of cuting force, is limited. This paper focuses itmay be found that compared with the wear of the mainon modeling of ctting forces and compares the modeling re- cuting edge, the wear of the axiliay cuting edge is verysults with cuting experimental resuls. It is concluded that small, therefore, may be ignored. As a reault, the cttingorthogonal cuting theory can be uwsed in plunge milling.force of the main cutting edge is considered mostly[8].1 ExperimentThe experiment platform is showm in Fig. 2, whichconsists of NC CENTER ( BJNC7150)，milling cutter,workpiece Al alloy (Type LY12), KISTLER measurementinstrument (TYPE 9257A)， KISTLER signal ampliferFig.3 Insert geometry mep(TYPE 5006), data acquisition instument (NI PCI-6221MCard) and a computer. The data acquisition and analysissystem is based on LABVIEW software.Tab.1 Insert perametersL, W/mm .R/mm7/()Cuttec12.71.2151:AmplierKISTLER. SumpleAs shown in Fig.4, the width of cutting varies withthe tuming ang]e of the main axis of the machine , and there(a) Manufacturing tesing platdom(b) Data acquitin ytenis an angle between the undefomned chip thickness and thefeeding diretion in Fig. 4, therefore, the crose sectional"g.2 Cutting force espertnentarea of the undefomed chip can be obtained by multiplyingthe widh of cutting by the undeformned chip thicknesel9],The cutting condition is as fllws:i.e.Cutting speed- 250 m/min;Cutting feed- -0. 25 mn/tooth;Cutting width- -8 mm;Cutting depb- 30 mm.2Mathematical model of cutting forcebased on orthogonal cutting theoryFirstly, we 8sumne that there is no temperaturechange, no machine vibration, or cooling factor. VibrationFg.4 Catting wildthand surface roughness experiments were done. R。 is only0.264 pum with cuting speed 45 m/min, cuting feed 0.04mn/tooth and cutting widh 8 mm. The results show thatwg=R-_R-ar .the stability of plunge miling is good. According to the pe-∞s(a-φ)rameters and geometric dimension of cutter, and with the(1)direction of cutter edge and cutting velocity vertical, thehs=f:"cos k,cutting manner is approximated as right- angle cutting, whichis based on the theary of two-dimensional cuting. As shownA= waghsin Fig. 3, the main and auxiliary cuting edges are both(3)working in the milling proce8s. In Fig.3, L is the length ofarsin[ R-(R- a2Pφ two teeth- + single tooth→two 4Conclusionteeth single tooth.It can be concluded through the single tooth cuttingAccordingly, p:0→0] - 90°→90°→θ→180-→θ + 90°→270°→and multiple teeth cutting simulation that cutting force sig-nal in experiments can be explained by the simulation re-θ + 180-→360°sult.中国煤化工matical model of plungewhere φ=2πnt; θ = arcos(1 -2ap/D);n is speed of millir: theory has a practicalprinciple axis, r/min;t is time, s; θ is angle from cuttingmeanYHC N M H Gion of ctting isert.in to cutting out.一306-QIN Xuda et al : Mathematical Model and Simulatin of Cutting Force in Plunge Milling ProcessManufawring Science and Enginering, 2007, 129(1):References32-40.[1] Guo Lianshui, Liu Qiufeng, Cao Haobo. Research and r[8] li henjia, Zhang Zhongmin, Yan Fugang et al. Waved-alization of optimized 5-axis NC machining method for tur-edge insert development and mlling fore mode[J]. Chi-bine blade[J]. 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