機械專業外文翻譯--Microthreading in Whirling微螺紋的旋風式加工 英文版

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1、Masaki SerizawaDepartment of Mechanical Engineering,Tokyo Denki University,5 Senjyu Asahi-cho,Adachi-ku,Tokyo 120-8551,Japane-mail:12ky044ms.dendai.ac.jpMotohiro SuzukiDepartment of Mechanical Engineering,Tokyo Denki University,5 Senjyu Asahi-cho,Adachi-ku,Tokyo 120-8551,Japane-mail:kettle-on-the-st

2、oveezweb.ne.jpTakashi Matsumura1Mem.ASMEDepartment of Mechanical Engineering,Tokyo Denki University,5 Senjyu Asahi-cho,Adachi-ku,Tokyo 120-8551,Japane-mail:tmatsumucck.dendai.ac.jpMicrothreading in WhirlingWhirling is applied to machining of microscrews on thin wires.A micro whirling machinehas been

3、 developed for this.In order to suppress the vibration of the workpiece,the wireis inserted in polyurethane tubes clamped on a metal bar.Frequency analyses have beenconducted by loading impulse forces at the center of the wire.The dynamic response isimproved with reducing the vibration in the clampi

4、ng force by the developed clampingsystem.Thirty micrometers microgrooves have been machined on 0.3mm diameter stain-less steel wires with fine surface finish,with the developed machine tool.DOI:10.1115/1.4030704IntroductionMicroscrews are used for mechanical joints and motion controlsin microdevices

5、.Stainless steel and titanium alloy,which aredifficult-to-cut materials,are used in medical and dental devicesbecause of their biocompatibility.Although,up to now,mostmicro-elements have been manufactured by chemical etching andenergy beam processes,some manufacturing cost and productionrate issues

6、remain.More effective and flexible processes arerequired for the mass production of microparts.Micromechanicalprocessing,one of the alternative processes,has remarkably pro-gressed with the development of microtools and motion controls.Many studies of microscale cutting,forming,and injection molding

7、have recently been applied to manufacturing of microparts 1,2.Thread whirling,which is a material removal process with tooland workpiece rotations,has been applied to screw manufacturingin many mechanical industries,since it was developed by theBurgsmuller company in Germany.Worm and ball screws for

8、motion controls and bone screws for the implant parts 3,whichare made of hard materials,have been machined by whirling.Having many advantages in terms of tool wear and chip control,whirling has been widely applied in the bearing and the medicalindustries.Mohan and Shunmugam presented a mathematicalm

9、odel to control the cutting processes and determined the toolprofiles in whirling 4.Lee et al.presented a model of the uncutchip shape to estimate the cutting force from the maximum chipthickness and the tool-work contact length.They divided theuncut chip shape into the material removed by the front

10、 cuttingedge and that by the side cutting edge;and estimated the cuttingforce by finite element(FE)analysis 5.Song and Zuo proposeda novel model based on the equivalent cutting volume and simu-lated the chip formation in a FE commercial tool,AdvantEdge6.Son et al.measured the cutting force component

11、s with a non-contact rotating tool dynamometer and compared the measuredforce with the simulations using the FE analysis tools,DEFORMandADAMS7.Guo et al.also analyzed the cutting tools processingangle in whirling 8.Although whirling is effective in threading,the screws are generally machined on larg

12、e diameter shafts.This study applies whirling to cutting threads on thin wires formicromechanical devices.The paper first presents an overview ofwhirling process along with its machining advantages.Based onthe whirling mechanism,a micro whirling machine tool has beendeveloped for machining microscre

13、ws on thin wires.Because thestiffness and the damping of the thin wire are low,a clampingdevice has also been developed to support the wire.Vibration testshave been conducted to verify improvement of the dynamicresponse of the workpiece with the clamping device.Microscrews have been machined on 0.3m

14、m diameter titaniumalloy and stainless steel wires with fine surfaces,using the devel-oped machine tool.A mechanistic model is described to obtainFig.1Thread whirling1Corresponding author.Contributed by the Manufacturing Engineering Division of ASME for publicationintheJOURNALOFMICRO-ANDNANO-MANUFAC

15、TURING.ManuscriptreceivedSeptember 1,2014;final manuscript received May 26,2015;published onlineAugust 13,2015.Assoc.Editor:Martin Jun.Journal of Micro-and Nano-ManufacturingDECEMBER 2015,Vol.3/041001-1CopyrightVC2015 by ASMEthe uncut chip thickness in terms of the cutting parameters.Theuncut chip t

16、hickness is discussed to validate its effect in the threadwhirling of thin wires.WhirlingWhirling is applied to machine screws by a combination of tooland workpiece rotations,as shown in Fig.1.The cutting tools areclamped on the whirling ring at the radius RT;and the ring rotatesat the angular veloc

17、ity xT.The workpiece with the radius RWrotates at the angular velocity xWin the whirling ring with theeccentricity e,which controls the depth of cut.In whirling,theworkpiece rotating at a low revolution rate is cut by the cuttingedges rotating at a high revolution rate.The lead of the screw iscontro

18、lled by the inclination and the feed rate of the whirling ringwith respect to the workpiece axis.In turning a small diameter workpiece,the cutting speed is con-strained to be low by the maximum limit of spindle speed and,asa consequence,the surface finish deteriorates.In whirling,the cut-ting speed

19、is controlled by the rotation radius RTand revolutionrate xTof the cutting tools on the whirling ring.Therefore,a finesurface can be finished on a thin wire at a high cutting speed eventhough the maximum spindle speed is limited.Because the tool and the workpiece rotate with eccentric cen-ters,cutti

20、ng and noncutting regimes alternate in whirling.There-fore,due to cooling during noncutting,the temperature rise of thetool edge is not so high.The material removal volume is also con-trolled to be small,as described later by the uncut chip thicknesscalculation model.The cutting force,thus,becomes s

21、mall in inter-rupted cutting.Because the tool wear depends on the stress and thetemperature 9,the tool wear is suppressed.Therefore,difficult-to-cut materials are machined with long tool lives in whirling.Because interrupted cutting is performed in whirling,the chipformation is intermittent and the

22、formed chips are short.Therefore,a fine surface is finished without scratching of the chipson the workpiece.Micro whirling Machine ToolMachine Tool Structure.Figure 2 shows the microwhirlingmachine developed for threading on thin wires with diameters of lessthan 1mm.A workpiece is clamped by collets

23、 in two hollow motors.One of the motors is mounted on two linear stages(X0-and Y0-axis)for straightness adjustment of the workpiece clamping with respectto the feed of the whirling ring.A motor rotates the tools on thewhirling ring.A rotation motor(A-axis)controls the inclination ofthe whirling ring

24、;and three linear stages(X-,Y-,and Z-axis)controlthe cutting position and the feed of the whirling ring.The rotationsof the whirling ring and the workpiece are controlled simultaneously,with the maximum spindle speed of the motors 4000rpm.The cutting tools are clamped on the whirling ring,as shown i

25、nFig.3.Because the tool edge alignment has an influence on themachining accuracy,the overhangs of the tools are adjusted with adevice shown in Fig.4.The workpiece is clamped in the opposedcollets,as shown in Fig.5(a).Workpiece vibration occurs becausethe stiffness of the thin wire is low and cutting

26、 is interrupted in thewhirling process.In order to support the workpiece,two closely fit-ting polyurethane tubes are slid over it,one to each side of the cut-ting area.These are then clamped in a groove on a supporting metalbar that protrudes through the whirling ring,as shown in Fig.5(b).This provi

27、des both high stiffness and damping for the workpiece.Dynamic Response of Clamped Workpiece.Dynamic responsetests were conducted to verify the effectiveness of the support sys-tem,as shown in Fig.6.The displacement of the thin wire couldnot be measured because the measuring area was small and withro

28、unded shape.Therefore,the amplitudes and the frequencies ofvibrations of the collet clamping forces were compared for threedifferent clamping conditions when an impulse force was gener-ated at the center of the wire.A 0.49N dead weight was hungfrom the wire by a thread.The impulse was generated by c

29、uttingthe thread by a burner flame.The resulting vibrations in clampingforce were measured with a piezoelectric dynamometer.Figure 7 compares Y(axial)and Z(vertical)components of theclamping force vibration,as designated in Fig.6.Figure 7(a)Fig.2Microwhirling machine toolFig.3Tool mounted on whirlin

30、g ringFig.4Adjustment of edge alignment041001-2/Vol.3,DECEMBER 2015Transactions of the ASMEFig.5Workpiece clamping system:(a)work area and(b)workpiece supporting deviceFig.6Impulse response testFig.7Vibration in clamping force:(a)wire without supporting device,(b)wire clamped onsupporting device,and

31、(c)wire clamped on supporting device with polyurethane tubesJournal of Micro-and Nano-ManufacturingDECEMBER 2015,Vol.3/041001-3shows a natural vibration without the support device.Large ampli-tudes in Y and Z components are measured and the vibrations con-tinue for a long time.Figure 7(b)shows the v

32、ibrations when thesupporting metal bar without polyurethane tubes restricts theworkpiece.The amplitude is restricted by contact with the grooveon the supporting bar.The vibrations last for around 1s.As maybe seen in Fig.7(c),support with the polyurethane tubes is effec-tive in controlling the vibrat

33、ion of the thin wire.A small ampli-tude of the vibration and a high damping are measured.Figure 8compares the frequency components of the vibrations.A largecomponent at 730Hz appears in the natural vibration of the thinwire,as shown in Fig.8(a).The supporting bar reduces this andshifts it to the hig

34、her frequency of 982 Hz,as shown in Fig.8(b).Figure 8(c)shows that supporting with the polyurethane tubesmountedonthesupportingbareliminatesanyprominentcomponents.According to the model tests,the developed supportsystem works well.Uncut Chip Thickness AnalysisIn order to support the choice of the cu

35、tting parameters in thecutting tests,the uncut chip thickness in the whirling process isconsidered here.Song and Zuo presented a model to obtain theuncut chip thickness in the general whirling process 6.In linewith the cutting demonstrated later in this study,a model isdescribed for whirling without

36、 the inclination angle of the whirlingring here.In the model,only the locus of the cutting point at thecenter of the cutting edge is discussed.Tool geometry is ignored.Tool Edge Motion.The workpiece rotates at the angular veloc-ity xWin the actual cutting,as shown in Fig.9(a).In the model,Fig.8Frequ

37、ency analysis:(a)wire without supporting device,(b)wire clamped on supportingdevice,and(c)wire clamped on supporting device with polyurethane tubesFig.9Whirling process:(a)actual cutting in whirling and(b)analytical model of whirling041001-4/Vol.3,DECEMBER 2015Transactions of the ASMEmeanwhile,the w

38、orkpiece does not rotate.Instead,the center oftool rotation OTrotates around the workpiece at the radius e at theangular velocity xWin the opposite direction to the tool rotatingdirection,as shown in Fig.9(b).XYZ is the reference coordinatesystem of the workpiece,where the origin OWof XYZ is thecent

39、er of workpiece.X0Y0Z0is the coordinate system of the toolrotating around OWand moving along the workpiece axis,Z.Then,the tool rotates at the angular velocity xTin the coordinatesystem X0Y0Z0.The coordinates(x0,y0,and z0)of a point P on an edge changewith the cutting time tx0y0z0264375 RTcosxTt uRT

40、sinxTt u0264375(1)where u is the angular position of the cutting edge.For example,when four edges are mounted on the whirling ring,the angles are0,p/2,p,and 3p/2,respectively.xTis negative because the rotat-ing direction is clockwise in Fig.9.Because the origin OTofX0Y0Z0rotates around the center of

41、 the workpiece OWat theradius e at the counterclockwise angular velocity xWand movesalong the Z-axis at the feed rate f,the point P on the edge inXYZ is transformed asxyz264375 cosxWt?sinxWt0sinxWtcosxWt0001264375x0y0z0264375?ecosxWt?esinxWtft264375(2)The material is removed when the rotation radius

42、 of P inXYZ is less than the workpiece radius RWffiffiffiffiffiffiffiffiffiffiffiffiffiffiffix2 y2p?R(3)Therefore,the cutting area is determined by Eqs.(2)and(3).Uncut Chip ThicknessFigure 10 shows the cutting area divided into regions AB andBC.In region AB,the uncut chip thickness is given by the c

43、ut-ting position P and a point Q1on the workpiece surface.In regionBC,the uncut chip thickness is given by P and a point Q2on thelocus of the previous edge at the prior angle c.c is the differencebetween the angular positions u.For example,when four edgesare mounted on the whirling ring,the angle c

44、is p/2.Because Q1or Q2is located on the extension line of OTP,the cutting thicknessis given by PQ1or PQ2.Q1or Q2is given byxyz264375 cosxWt?sinxWt0sinxWtcosxWt0001264375ncosxTt unsinxTt u0264375?ecosxWt?esinxWtft2435(4)where n is the parameter that determines Q1or Q2.When materialis removed,n is lar

45、ger than RT.In region AB,n at Q1is deter-mined by the following equation of the workpiece surface andEq.(4):xyz264375 RWcoshRWsinhft264375(5)where h is the angle of Q1in the workpiece coordinate systemXYZ.In region BC,the previous edge at the prior angle c is given ata time of t?c=xTDtxyz2666437775c

46、osxWt?c=xTDt?sinxWt?c=xTDt 0sinxWt?c=xTDt cosxWt?c=xTDt00012666437775?RTcosxTt?c=xTDtuRTsinxTt?c=xTDtu02666437775?ecosxWt?c=xTDt?esinxWt?c=xTDtft?c=xTDt2666437775(6)where Dt is determined so that Q2is on the extension of line OTP.n at Q2is determined to satisfy Eqs.(4)and(6).Because the feedalong Z-

47、axis is very small in one revolution,it is ignored and n isdetermined in XY plane.The uncut chip thickness is given by thefollowing equation with the determined n:t1 n?RT(7)Figure 11 shows the change in the uncut chip thickness in XYplane when a screw is machined on a 0.3mm diameter wire.Fig.10Cutti

48、ng area in whirlingFig.11Uncut chip thicknessJournal of Micro-and Nano-ManufacturingDECEMBER 2015,Vol.3/041001-5Workpiece revolution speed is 0.5rpm and four cutting tools,mounted on a whirling ring,rotate at 3000rpm at a rotation radiusof 14mm.The feed rate is 0.2mm/min.The depth of cut is 30lmwith

49、 an eccentricity of 6.88mm.Figure 12(a)shows a quarter ofthe workpiece.At this scale,the cutting area is small.Figure 12(b)shows the magnified figure.The cutting edge penetrates into theworkpiece at A;passes B at the maximum uncut chip thickness;and exits from the workpiece at C.From A to B,the remo

50、ved areais between the workpiece surface and the locus of the tool.Theuncut chip thickness increases at a high rate of change over thetime(Fig.11)from?0.04128ms to?0.04125ms.Then,from Bto C,the removed area is between the loci of the tool and the pre-vious tool.The uncut chip thickness gradually dec

51、reases after?0.04125ms,as shown in Fig.11.The analysis here is for cutsother than the first cut.The uncut chip thickness is actually 30lmat the first engagement of an edge into the workpiece becausethe uncut chip thickness is determined only by the area betweenFig.12Locus of tool motion with workpie

52、ce surface:(a)in a quarter of workpiece and(b)magnifiedFig.13Machining examples:(a)example 1,(b)example 2,and(c)example 3Table 1Cutting parametersExample 1Example 2Example 3WorkpieceTi-6Al-4VStainless steelStainless steelWorkpiece diameter0.3mmWorkpiece revolution0.5rpmToolTiAlN coatedcarbide toolTo

53、ol wedge angle60degTool rake angle0degNumber of tools411Tool rotation diameter14mmTool spindle speed3000rpmFeed rate0.2mm/min1.0mm/minDepth of cut30lm40lmLubricationDry041001-6/Vol.3,DECEMBER 2015Transactions of the ASMEthe workpiece surface and the locus of the tool.After the secondengagement of th

54、e edge,the maximum uncut chip thicknessis no more than 0.02376lm.This is much smaller than thedepth of screw of 30lm.According to the research in microcut-ting 10,chips form when the uncut chip thickness is morethan“minimum chip thickness.”Because the analyzed cuttingthickness,0.02376lm,is much smal

55、ler than the minimum chipthickness,material removal is expected to occur for only somecuts of the edges.The analysis supports the choice of cuttingparameters for small cutting forces associated with the cuttingthicknesses.Cutting TestsFigure 13 shows examples of microthread whirling on titaniumalloy

56、(Ti-6Al-4V)and stainless steel wires,where the diametersare 0.3mm.The threads were machined with single point toolswith a wedge angle of 60deg.The tool material was TiAlN coatedcarbide.Table 1 shows the cutting parameters that were used.Figure 13(a),example 1 shows serration on the surface finishwit

57、hin a screw cut by four edges.Although the alignment of thefour edges is controlled in the radial direction,as shown in Fig.4,there is alignment error in the axial direction.This induces the ser-ration.Figure 13(b),example 2 shows a screw cut on stainlesssteel wire by one edge.Figure 14(a)shows the

58、surface profilealong the line designated in Fig.14(b).The surface profile ismeasured with a laser confocal microscope.Although burr forma-tion at a height of 10lm is observed at the left side of the groove,the depth of groove is as specified.It demonstrates the effective-ness of the high stiffness o

59、f the workpiece support system.Thepresented whirling also enables a high lead screw to be machinedat a feed rate of 2.0mm/rev(1.0mm/min),as shown in example 3of Fig.13(c).Because the cutting speeds depend on the rotation diameters ofthe tools on the whirling ring,surfaces are finished at high cut-ti

60、ng speeds.The cutting speeds of these examples are 132m/minat a tool rotation diameter of 14mm and a spindle speed of3000rpm.In turning,a spindle speed of 140,056rpm would berequired to give same cutting speed for the 0.3mm diameterworkpiece.The groove shapes in whirling are uniform withoutadhesion

61、of the chips.These examples prove that whirling iseffective in microthreading with the presented supporting deviceof the workpiece.ConclusionsWhirling has been applied to machining of microscrews on thinwires.In the whirling cut,the workpiece and the tool rotate withan eccentricity of their centers.

62、Because the material is removedin a small volume at a high cutting speed,the whirling has advan-tages in surface finish,tool wear,and chip control compared toturning.A microwhirling machine tool has been developed for machin-ing of the microgrooves on the thin wires with diameters of lessthan 1mm.In

63、 order to improve the stiffness and the damping ofthe workpiece,the wire,which is clamped between collets,is alsosupported on a metal bar by inserting it into a closely fitting poly-urethane tube.Dynamic response tests have been conducted toverify the effect of the supporting system.The amplitudes a

64、nd thefrequencies of the vibrations of the collet clamping forces weremeasured when impulse forces were loaded at the center of thewire.They show the effectiveness of the supporting system insuppressing the vibration.A mechanistic model is applied to consider the small uncutchip thickness.Microgroov

65、es have been machined on 0.3mmdiameter titanium alloy and stainless steel wires.Because a highcutting speed can be maintained by the rotation radius of the tool,the surface finish is improved without adhesion of the chips.Inthe presented machining example,the uncut chip thickness ismuch smaller than

66、 the depth of the groove.Because the uncutchip thickness is associated with the cutting force,the specifieddepth of groove is generated with a small cutting force,with ahigh stiffness of workpiece holding system.References1 Cheng,K.,and Huo,D.,2013,Micro-Cutting:Fundamentals and Applications,Wiley,Hoboken,NJ.2 Vollertsen,F.,Hu,Z.,Niehoff,H.S.,and Theiler,C.,2004,“State of the Art inMicro Forming and Investigations Into Micro Deep Drawing,”J.Mater.Process.Technol.,151(13),pp.7079.3 Yokoyama,K.,Ic