機(jī)械設(shè)計(jì)外文翻譯-通過(guò)立式六軸控制并應(yīng)用超聲振動(dòng)加工銳角轉(zhuǎn)角【中英文WORD】【中文5570字】

機(jī)械設(shè)計(jì)外文翻譯-通過(guò)立式六軸控制并應(yīng)用超聲振動(dòng)加工銳角轉(zhuǎn)角【中英文WORD】【中文5570字】,中英文WORD,中文5570字,機(jī)械設(shè)計(jì),外文,翻譯,通過(guò),立式,控制,應(yīng)用,超聲,振動(dòng),加工,銳角,轉(zhuǎn)角,中英文,WORD,中文,5570 International Journal of Machine Tools&Manufacture 44(2004) control cutting of overhanging curved grooves by meansof non-rotational tool with application of ultrasonic vibrationsFeliciano H.Japitanaa,1,Koichi Morishigea,1,Yoshimi Takeuchib,?aDepartment of Mechanical Engineering and Intelligent Systems,The University of Electro-Communications,1-5-1,Chofugaoka,Chofu-shi,Tokyo 182-8585,JapanbDepartment of Computer-Controlled Mechanical Systems,Graduate School of Engineering,Osaka University,2-1,Yamadaoka,Suita,Osaka 565-0871,JapanReceived 10 July 2003;received in revised form 2 November 2003;accepted 13 November 2003AbstractThis paper presents a new machining method that efficiently cuts overhanging curve grooves on wall surfaces without causing acollision between the tool and the workpiece.It also describes the development of software for 6-axis control grooving and theeffect of applied ultrasonic vibrations(USV)in cutting overhanging grooves(OHG).In general,rotational tools are used to pro-duce grooves,thus resulting in long circular arc segments at the cutting end points,as well as placing restrictions on the manufac-ture of grooves with continuous change in curvature,while ensuring that they do not overshoot the side clearance angle of thecutting edge with the groove.The study aims at machining OHGs presently impossible to machine by conventional methods.From the experimental results,it was found that the new machining method,which is 6-axis control cutting using a non-rota-tional tool with the application of USV,is capable of cutting an OHG on wall surfaces correctly.#2003 Elsevier Ltd.All rights reserved.Keywords:Overhanging grooves;6-Axis control cutting;Non-rotational tool;Ultrasonic vibrations;CAD/CAM system1.IntroductionWith the increasingly shortened life cycles of con-sumer goods of late,new products are put on the mar-ket one after another in half a year or a year.Manysophisticated designs of industrial products are adoptedto meet the latest requirements,which drasticallyincreases the demand for producing workpieces withcomplicatedshapes.Thus,moldsmustbemanu-factured to cope with production in small quantitiesand they have to be low in cost,quick in delivery andflexible in manufacturing process due to the complexityof shape.Flexibility is one of the benefits of smallbatch manufacturing.While a small batch shop mayhave a lower unit output than a shop dedicated to oneor two lines,its strength is that it can make a variety ofcomplex products in small volumes.Under the circum-stances,the concept of simplified molds was formed,and one of these is by using aluminum materials.Aluminum alloy can be utilized for producing moldswith low molding pressure,such as by blow molding,vacuum forming,rubber forming,etc.Rotational tools are used to increase the cuttingspeed,a process known now as high speed cutting;however,shaving remnants are formed according tothe tool shape at the end corner of the product,asshowninFig.1(a).Thislimitationisinevitable,especially when employing rotational tools in the pro-cess.In general,rotational tools are used to producegrooves on certain products;however,they generate along circular arc segment at the cutting end point,asillustrated in Fig.1(b).Also,if the groove is located onthe overhanging surfaces of the products,as shown inFig.2,it is difficult or impossible to machine it by con-ventional methods.If the limitation in the manufactur-ing process can be minimized or eliminated 1,2,then?Corresponding author.Tel.:+81-6-6879-7339;fax:+81-6-6879-7247.E-mail address:takeuchimech.eng.osaka-u.ac.jp(Y.Takeuchi).1Tel.:+81-424-43-5411;fax:+81-424-84-3327.0890-6955/$-see front matter#2003 Elsevier Ltd.All rights reserved.doi:10.1016/j.ijmachtools.2003.11.002the efficiency and adaptability of the products can beextended greatly 3.The study aims at producing an overhanging groove(OHG),which is impossible to manufacturecon-ventionally.Customarily,grooves are manufactured ina linear direction especially if the groove is located onthe wall of the product and it is processed using a rota-tional cutting tool such as a T-slot cutter or woodruffkey seat cutter.To date,there are few CAM softwareprograms intended for side grooving available in themarket.Most of these are limited to only 2-to 3-axiscontrol machining.In this study,the OHG is manufactured by means ofa 6-axis control cutting using a non-rotational toolwith the application of ultrasonic vibrations(USV).Since the cutting speed in a non-rotational tool is verylow,as it is equal to the applied feed speed,and thematerial of the workpiece is a non-ferrous metal likealuminum alloy,it tends to affect the surface quality ofthe product as well as productivity.The low cuttingspeed will lead to the removal of less material in agiven amount of time,which could be economicallyundesirable.In this sense,high speed machining isnecessary for efficient machine and to have a good sur-face finish.In addition,high speed machining has beenknown as giving a technological solution for high pro-ductivity,as it increases economic efficiency in manu-facturing as well as improves the surface quality.Thecutting phenomenon in such a low cutting speed regionhas not been clarified;however,the effect of cuttingspeed in machining an aluminum alloy has alreadybeen elucidated.The cutting speed tends to affect thesurface quality of the product due to the formation ofthe built-up edge,especially for non-ferrous materialslike aluminum alloy 4.In order to increase the cuttingspeed of the non-rotational tool,USV is applied to thenon-rotational tool,since it has made great contribu-tions in different fields of applications 58.The effectof USV in terms of surface appearance and cuttingforce were also investigated.The result shows that thesurface roughness in cutting with USV was greatlyimprovedandthecuttingforcewasdramaticallyreduced.In the study,the efficiency of cutting withUSV is experimentally confirmed,and the machining ofOHGs is done using the new machining method withthe aid of the developed CAM software.2.CAD/CAM system for machining of OHGA CAD/CAM system is indispensable for machiningan OHG efficiently with ease and without collision.The software development for cutting OHGs is con-ducted in the engineering workstation using a solidmodeler named DESIGNBASE as a kernel.The CAD/CAM system for machining OHGs is composed of thefollowing:the main processor and the postprocessor.The main processor generates the cutter location(CL)data,while the postprocessor converts CL data intonumerical control(NC)data.2.1.Main processor for OHG cuttingThe main processor was developed utilizing C lan-guagewiththebasiclibraryfilesprovidedbyDESIGNBASE(Ricoh Co.,Ltd.)software.Based onthe geometric information of the OHG obtained fromthe 3D-CAD data of the workpiece,the main processorFig.1.Results of machining with rotational tool.(a)Cutting withrotational tool(ball end mill);(b)cutting with T-slot cutter.Fig.2.Groove on overhanging surface of the product.480F.H.Japitana et al./International Journal of Machine Tools&Manufacture 44(2004)479486generates the position of the cutting point(P),the nor-mal vector(N)and the feed vector(F).The PNF dataare generated on the basis of the cutting tool shape,thecutting direction and the depth of cut.The cuttingdirection is decided based on the structure of the tooland the location of the OHG.If the opening of theOHG is located on the right hand side of the surfaceand close to the end,as shown in Fig.3(a),the cuttingdirection to be used for generating the PNF data willdepend on the left-handed non-rotational tool,and ifthe opening of the OHG is on the opposite side,asshown in Fig.3(b),the same procedure will be used;however the bases of generating the PNF data for cut-ting direction will be the right-handed non-rotationaltool.Fig.4(a),(b)shows the types of non-rotationaltools used for generating PNF data.The number ofdivisions in the direction of the groove determines thedepth of cut.The number of divisions being input,thesystem automatically computes the depth of cut.In acurved OHG,the number of divisions on the length ofsurface greatly affects the curvature of the OHG.Whenthe number of divisions increases to create the curvedOHG accurately,the cutting points generated by thesystem also increase.On the other hand,in linearOHG,the number of divisions is not so importantsince it deals only with a straight groove.After the PNF data are generated,they will be con-verted into CL data using the same main processor.The main processor generates collision-free CL data,based on the structure of the OHG,the cutting toolinformation and the vibration conditions.The CL dataare obtained by selecting the bottom surface of thegroove.The depth of cut and the number of divisionsin the PNF data are then input again.Shown in Fig.5is the tool attitude denoted by the coordinates P forcutting point,T for tool axis vector and D for tooldirection vector.The cutting points P are sequentiallygenerated,based on the generated PNF.The tool axisvector T is modified based on the vibration direction ofthe USV,which is 10v;it is rotated in order to makethe vibration direction parallel to the cutting direction.This axis is transformed to modified tool axis vectorTm.Collision check is carried out in this process,butcollision avoidance is not performed in this operation.The entry and exit points of the cutting tool are veryimportant,especially in dealing with an OHG that isclose to the end surface.The entry and exit points areadded to the CL data before converting to NC data.2.2.Postprocessor for OHGThe CL data generated by the main processor,the P,T,and D vectors,are changed into specific NC data bythe postprocessor.The NC data are identical to theexpression with regard to tool posture.They consist ofthe coordinate values of the cutting points and theangle expression of the tool posture.Fig.6(a)showsthe measured offset distance value in the X-direction(Dx)and that in the Y-direction(Dy)of the cutting tipFig.3.Arrangement of PNF data for groove.(a)Left side groove;(b)right side groove.Fig.4.Types of non-rotational tool used for OHG cutting.(a)Right-hand type;(b)left-hand type.Fig.5.Tool attitude determination for non-rotational tool.F.H.Japitana et al./International Journal of Machine Tools&Manufacture 44(2004)479486481of the non-rotational tool.These offset values arerequired to make the location of the cutting tipcoincide with the origin of the workpiece coordinatesystem,as shown in Fig.6(b).The NC data converted from the CL by the post-processor,in turn,are used in the machining operationof the OHG.The NC data control the movement ofthe tool and all of the axes.Converting the CL usingthe postprocessor produces such NC data.3.Experimental procedure and parameters3.1.Experimental setup and conditionsThe photograph of the experimental setup is shownin Fig.7.The new machining system comprises the fol-lowing:6-axis control machine,CAD/CAM system,non-rotational tool and USV tool.The non-rotationaltool is attached to the USV using an adaptor,while theUSV,in turn,is attached to the main spindle of the 6-axis control machine.The CAD/CAM system dictatesthe movement of the machine axes by synchronous cut-ting the product to its required shape.The 6-axis control machine tool used in the study isa multi-axis machine tool made by Makino Milling Co.(GN107),shown in Fig.8(a).It provides multiple-axismachining capabilities beyond the standard 3-axis con-trol.It is constructed by adding the rotational functionCsto the main spindle of the 5-axis control machinewhich has simultaneous contouring axes A and B.Fig.8(b)shows the designations of the rotary motionson the three translational axes,X,Y,and Z.Rotarymotions about the X-axis as well as the Y-and Z-axisare designated A,B and C,respectively.The position-ing accuracy of movement(X,Y,and Z)is 1 lm,andthat of rotation(A,B and C)is 0.36 arc second.Incase of OHG cutting,the depth of cut is determined byeither the X-or Y-axis.Rotation of the workpiece isexecuted by the B-axis and inclination is carried out bythe A-axis.The machine specifications are also shownin Fig.8(c).The cutting tool design has a strong impact onmachining performance.Cutting tools may be broadlyclassified into either single point or non-rotational,having only one active cutting edge,and into multi-point tools,which have multiple active cutting edges.Single point tools are commonly used for turning andboring operations;however,in the study,we utilizedone as a non-rotational tool in 6-axis control cutting ofOHG due to its unique shape and size.The overalllength and diameter of the non-rotational tool are 70and 6 mm,respectively.The material of the cuttingtool used is tungsten carbide.In the case of cutting anOHG,the width of cut is already decided to be 2 mmdue to the structure of the tool.In order to cut non-ferrous material like aluminumalloy efficiently,it is required to cut it by high speedmachining,and though a non-rotational tool is beingused in this study,it is difficult to obtain such a highcutting speed since the cutting speed is equal to thefeed speed of the cutting tool.In this case,USV isapplied to increase the cutting speed of the non-rota-tional cutting tool.The USV cutting unit used in thestudy is a commercially available one(SB-150:TagaElectric Co.).The vibration occurs at of 10vto the cut-ting point of the tool,as shown in Fig.9(a).The tip ofthe non-rotational cutting tool is oscillated by thebooster and sonotrode at a frequency of about 19 kHzwith an amplitude of 35 lm.Obtaining effective andefficient vibration cutting requires the USV direction tobe parallel to the cutting direction.The vibration direc-tion is corrected in line with the generation of CL data.Fig.9(b)shows the cutting tool position and thevibration direction after applying the correction angle.4.Fundamental results and discussion4.1.Cutting forcesThe relationship between the cutting force and thechange in cutting speed were examined.The principalFig.6.Position of cutting tool point.(a)Before tool offset;(b)aftertool offset.Fig.7.Photograph of experimental setup.482F.H.Japitana et al./International Journal of Machine Tools&Manufacture 44(2004)479486cutting force Fywas measured using a piezoelectricdynamometer(9257B Kistler Co.,Ltd.)installed on thetop of the table of the 6-axis control machine.Fig.10illustrates the relationships between these cutting forcesand the cutting speed.The cutting forces decrease withthe increase of cutting speed 9.The reduction of cut-ting forces can be explained by the reduction in fric-tional forces because of intermittent cutting during theapplication of USV.In this process,the cutting toolhits the workpiece 19,000 times a second with theapplied frequency of the USV.Also,the comparison ofcutting force between cutting with USV and withoutUSV has been made,as shown in Fig.11;it is evidentthat the cutting force in cutting with USV is muchlower than that in cutting without USV.4.2.Surface appearanceSurface finish is one of the key factors in producinga good quality product,especially in the mold industry.If a mold is made of non-ferrous material like alumi-num alloy,it requires a high cutting speed in order toproduce a good surface appearance.Since the cuttingtool used in the study is a non-rotational one,it affectsthe surface finish of the product due to the very lowcutting speed,as it is just equal to the applied feedspeed.Such a cutting speed usually results in the for-mation of a built-up edge.The built-up edge is anaccumulation of heavily strained work material,beingcollected on the cutting edge under certain conditions.This is an undesirable feature for several reasons.Itreduces the quality of the machined surface because itFig.8.Configuration of 6-axis control machine tool.(a)Structure of 6-axis control machine;(b)designated motion on axis;(c)specification of6-axis control machine tool.Fig.9.Vibration direction and position of cutting tool.(a)Beforesubjecting to tool arrangement;(b)after subjecting to tool arrange-ment.Fig.10.Measured cutting force.F.H.Japitana et al./International Journal of Machine Tools&Manufacture 44(2004)479486483periodically breaks offand re-forms,introducing irre-gularities into the surface.Built-up edge formation isstill a problem in low cutting speed processes especiallyfor soft,ductile work material such as aluminum alloys10.Since the built-up edge is such an undesirable fea-ture,it is of great interest to investigate how it may beavoided.The standard method of reducing or eliminat-ing built-up edge formation is to increase cutting speed,while an other effective method is applying a lubricantor coolant to reduce toolchip friction.To solve theproblem of low cutting speed in a non-rotational tool,USV has been applied in the process.The cutting speedhas been enhanced by the application of USV.To fur-ther verify the efficaciousness of the system,a set ofexperiments were conducted.Machining with the appli-cation of USV and without USV has been done.Fig.12shows the results of the surface finish produced by cut-ting with USV and without USV.The surface finish incutting with USV is uniform,as compared to cuttingwithout USV.The surface appearance was photo-graphed using an analog camera(EOG CVC-6811LN).The surface roughness was measured using a surfaceroughness-measuring device(SV 400 Mitutoyo Co.,Ltd.)and the results are shown in Table 1.4.3.Efficiency of cuttingTo substantiate the efficiency of cutting with USV,additional experiments were conducted.Machining ofgrooves with the application of USV and without USVhas been done.The machining conditions for cuttingboth with and without USV are the same:a depth ofcut of 0.1 mm and feed speed of 800 mm/min.The fol-lowing vibration conditions were applied in cuttingwith USV:a frequency of 19 kHz,amplitude of 36 lmand rolling angle of 10v.The groove has a total depthof 2 mm and a total length of 94 mm.The width of cutis set to be 2 mm due to the structure of the tool.Theworkpiece material is an aluminum alloy(A5052).In cutting with USV,the cutting speed increases,andthe required depth of cut has been obtained withoutdifficulty on the part of the cutting tool.High cuttingspeed greatly reduced the cutting force,which resultedin maintaining the stiffness of the cutting tool whilemachining the product.The measured total depth ofFig.11.Comparison of cutting force.Fig.12.Surface appearance of machine workpiece.(a)WithoutUSV;(b)with USV.Table 1Comparison of surface roughnessCuttingRy(lm)cross feed directionWith USV3.59Without USV7.81Fig.13.Machining of OHG.(a)Actual machining of OHG(straight type);(b)actual machining of OHG(curve type).484F.H.Japitana et al./International Journal of Machine Tools&Manufacture 44(2004)479486cut after the process is 2.017 mm quite close to the tar-get depth of 2.00 mm,without considering machineerror and setup error.In cutting without USV,only 10 passes have beenattained;the tool was broken on the 11th pass.As thecutting depth grows,increase in cutting force is inevi-table due to the continuous contact of the tool with theworkpiece,which affects the stiffness of the cuttingtool.If the cutting tool cannot withstand the pressure,it tends to break down.The resulting measured depthafter 10 passes is 0.639 mm,far from the expecteddepth of 1.0 mm,since the depth of cut is 0.1 mm.5.Machining of overhanging groovesThe cutting experiment has been done in order toverify the validity of the developed software as well asthe new machining method.The overall size of theworkpiece is 80?80?40 mm and the material is analuminum alloy(A5052).Two types of OHG havebeen cut in the study,namely the straight type groovewithin the pocket and the curved type groove with aclosedend-surface,as shown in Fig.13(a),(b),respect-ively.The total depth of cut and the minimum width ofcut were limited to only 2.0 and 2.0 mm,respectively,due to the size and construction of the cutting tool.Rough cutting has been done by 3-axis control cutt