試驗(yàn)指導(dǎo)書(shū)：五軸數(shù)控磨刀機(jī)原理及實(shí)踐

1、實(shí)驗(yàn)指導(dǎo)書(shū)五軸數(shù)控磨刀機(jī)原理及實(shí)踐要加工出合格的工件，必須根據(jù)工件的加工工藝要求，正確地設(shè)計(jì)和使用刀具，以保證 達(dá)到工件所要求地尺寸、形狀精度和表面質(zhì)量。金屬切削刀具的種類(lèi)很多，對(duì)于標(biāo)準(zhǔn)刀具， 需要根據(jù)刀具的工作原理和結(jié)構(gòu)特點(diǎn)正確地選擇和使用；對(duì)于非標(biāo)準(zhǔn)刀具則需要根據(jù)工件的 加工要求進(jìn)行專(zhuān)門(mén)的設(shè)計(jì)和制造。經(jīng)過(guò)精心準(zhǔn)備，制造工程基礎(chǔ)教學(xué)組與德國(guó)saacke公司培訓(xùn)中心嘗試進(jìn)行校企合作 開(kāi)展學(xué)生實(shí)驗(yàn)課程的工作。本次實(shí)驗(yàn)的主要目的是結(jié)合生產(chǎn)實(shí)際，通過(guò)先進(jìn)的制造設(shè)備及手 段，使學(xué)生能夠掌握刀具的設(shè)計(jì)原理，合理選擇刀具設(shè)計(jì)參數(shù)，正確設(shè)計(jì)刀具結(jié)構(gòu)，熟悉刀 具從設(shè)計(jì)到制造的全過(guò)程。實(shí)驗(yàn)?zāi)康慕Y(jié)合生產(chǎn)實(shí)際，給學(xué)

2、生介紹先進(jìn)的生產(chǎn)理念，作為課堂內(nèi)容的拓展和補(bǔ)充，加深對(duì) 所學(xué)知識(shí)的理解；鍛煉實(shí)驗(yàn)設(shè)計(jì)能力和動(dòng)手能力，熟悉刀具由設(shè)計(jì)到制造的全過(guò)程；掌握有關(guān)磨削加工的知識(shí)，了解刀具磨床的結(jié)構(gòu)及工作原理，；掌握鉆頭設(shè)計(jì)、加工的全過(guò)程；指導(dǎo)人員德國(guó)Saacke公司中國(guó)工程師、德國(guó)工程師（英語(yǔ)交流）、實(shí)驗(yàn)指導(dǎo)教師實(shí)驗(yàn)內(nèi)容由Saacke公司的指導(dǎo)人員負(fù)責(zé)講解，并利用該公司所提供的五軸數(shù)控磨刀機(jī)及相應(yīng)的 CAD/CAM軟件，參加實(shí)驗(yàn)的每組同學(xué)完成所選刀具的設(shè)計(jì)和制造。本實(shí)驗(yàn)主要包括以下內(nèi)容：講解Saacke五軸新概念刀具磨床的結(jié)構(gòu)及工作原理。講解鉆頭、銑刀等刀具設(shè)計(jì)、加工原理講解有關(guān)磨削加工的知識(shí)，包括砂輪、切削液等在刀

3、具設(shè)計(jì)加工仿真軟件上完成相應(yīng)刀具的CAM設(shè)計(jì)在Saacke五軸刀具磨床上完成所設(shè)計(jì)刀具的加工實(shí)驗(yàn)設(shè)備、儀器及工具機(jī)床：uw型五軸數(shù)控磨床軟件：NUMROTO plus試件：45#鋼棒料（細(xì)長(zhǎng)棒料）計(jì)算機(jī)千分表、游標(biāo)卡尺刀具角度測(cè)量?jī)x準(zhǔn)備工作熟悉鉆頭、銑刀的結(jié)構(gòu)特點(diǎn)、設(shè)計(jì)原理和制造方法；熟悉本指導(dǎo)書(shū)附錄中關(guān)于磨削的知識(shí)；牢記操作注意事項(xiàng)及操作安全。UW II型五軸數(shù)控磨床簡(jiǎn)介圖1. 1】型五軸數(shù)控磨床UW型五軸數(shù)控磨床，功率15KW,可以用于刀具的制造和修磨，并可配置自動(dòng)上下 料裝置，以滿(mǎn)足大批量生產(chǎn)的需要。機(jī)床采用Windows操作系統(tǒng)，人機(jī)對(duì)話(huà)式窗口，界面 友好，旁邊有圖形支持窗口，可對(duì)加工

4、刀具進(jìn)行三維立體顯示和加工模擬，并且留有用戶(hù)開(kāi) 發(fā)界面。在磨頭上裝有三維Renishaw測(cè)頭，可以對(duì)刀具的長(zhǎng)度、直徑、螺旋角等參數(shù)進(jìn)行 自動(dòng)測(cè)量，并自動(dòng)輸送到計(jì)算機(jī)中，方便可靠。該機(jī)床主要技術(shù)參數(shù)如下：技術(shù)特點(diǎn)： 轉(zhuǎn)塔式磨頭，裝有三根砂輪芯軸，可配9片砂輪磨軸馬達(dá)功率15KW 數(shù)字控制 磨軸轉(zhuǎn)速2,000-8,000 rpm一 工件頭直接驅(qū)動(dòng)，轉(zhuǎn)速600 rpm (可選)自動(dòng)上料系統(tǒng)(可選)每個(gè)托盤(pán)最多可裝40把刀具工件參數(shù)： TOC o 1-5 h z 最大直徑300mm全磨制最大直徑250mm全磨制最大切削刃長(zhǎng)350mm實(shí)驗(yàn)報(bào)告實(shí)驗(yàn)?zāi)康膶?shí)驗(yàn)內(nèi)容實(shí)驗(yàn)步驟實(shí)驗(yàn)結(jié)果利用刀具設(shè)計(jì)加工CAD/CAM

5、軟件系統(tǒng)NUMROTO plus完成相應(yīng)刀具的 CAM設(shè)計(jì)利用UW型五軸數(shù)控刀具磨床和棒料加工出所設(shè)計(jì)的刀具給出設(shè)計(jì)加工的鉆頭的測(cè)量角度實(shí)驗(yàn)分析與總結(jié)分析所設(shè)計(jì)鉆頭結(jié)構(gòu)特點(diǎn)和刀具幾何參數(shù)對(duì)加工的影響；分析五軸數(shù)控磨床的工作原理以及砂輪的特性由哪些因素決定；分析切削液的種類(lèi)及切削液的使用情況對(duì)磨削加工的影響；對(duì)本次實(shí)驗(yàn)的感想與建議；建議建議大家在實(shí)驗(yàn)前做好準(zhǔn)備工作，在實(shí)驗(yàn)中每組同學(xué)可進(jìn)行分工，以提高實(shí)驗(yàn)效率。附錄GrindingGeneral introductionGrinding means cutting with geometrically not defined edges. The

6、rotating grinding bodies are composed of bound abrasive grains and imbedded pores, functioning as chip chambers. 我Advantages of grindingHigh surface quality of the ground partsGood machinability of hard and difficult to machine materialsHigh time grinding volume. Partially, similar values as for pla

7、ning and turning are possible.Surface grinding machinesOn surface grinding machines plane surfaces are machined by the periphery or by the face of the grinding wheel (figure). There are different kinds of machines: one execution with horizontal and vertical grinding spindle, the other with long and

8、with rotary table.Long tables are meant for bigger resp. longer working pieces.Round or rotary tables are suited for smaller pieces. Smaller pieces do not need the change of direction at the end. Therefore a continuous feed motion is possible.On grinding machines the tool (grinding wheel) is effecti

9、ng the cutting movement. Depending on the machine type or design, the plunge and the feed motion are effected either by the working piece or by the tool.Surface cylindrical grinding machinesOn these machines the working piece is mostly clamped between the centers. It gets a rotary motion. The cuttin

10、g movement is effected by the grinding wheel. The grinding wheel can be fed from behind to the working piece.Long working pieces require a longitudinal feed (figure), which is mostly effected by the working piece. Here a slide (working piece slide) is required, which can be adjusted to different str

11、oke lengths. The working piece table is fixed on the slide.Machines with a horizontal spindle are mostly usedfor periphery grinding. In figure * you can see differentexamples of use. Vertical spindles are often used for face grinding.On both machine types the slides are mostly hydraulically operated

12、. Hydraulic drives are vibration free, the feed is infinitely variable. High quality slide guides and good lubricant conditions on the guide surfaces are very important in order to avoid the stick-slip-effect. Also very important are good spindle bearing assemblies.References/characteristics of a gr

13、inding wheelOn figure 1 (pagel) you can see the body of a grinding wheel. The figure shows the abrasive grains, the bonding material and the pores. When selecting the suitable grinding wheel, five decisions have to be made.1. Abrasive material (chemical composition of the abrasive grain). The most i

14、mportant abrasive materials are:corundum A, silicon carbide C, boron nitride B and diamond D. Corundums are mainly composed of aluminium oxide (Al2O3). You have to differ between several degrees of purity. Normal corundum: 94.97H% AI2O3, special fused alumina: more than 99% AI203. Corundums are for

15、example suited for the grinding of long cutting materials. Silicon carbide is harder. It is suited for the grinding of short cutting materials as for examplegray iron, chill casting, carbide.2. Granulation (grain size)In the standard designation the grain size is specified with a number, for ex. 80.

16、It specifies the number of meshes (per inch)of a filter by which the grains wereEgrobmtCtcl.,sdvfcin310121416 2G24.二 m303660- ； : A VW100120 160 1802/0 2402S0 320 400 bOO 600 aoo1000 1200 .sorted out.Hardness (Resistance of the grains against breaking out of the bonding).As every cutting tool does -

17、 grains are dulling after a certain time. When the wheel hardness is selected correctly, the dulled grain breaks out due to the higher loading and allows therefore, that new, sharp grains can work. The material of the working piece has a big influence on the hardness selection. Here you have to cons

18、ider:Hard materials require soft wheels, soft materials require hard wheels.When hard materials are machined the grains are dulled earlier and have to disconnect earlier from the bonding. The hardness (one letter for ex. nMH) refers to the stationary wheel.ABCDau&erst weichEFG一Sehr weichH1JotKweichL

19、MNOmittrlPQRShartTUVwsehr hartXYZ一auBerst hartSAACKE Workshop GRINDING contact zone).During internal grinding the grain is charged less and rests therefore longer in the bonding. So the wheel seems harder. In the following you find other possibilities, how to increase the active hardness (preconditi

20、on: the other machining data stay the same).setting a new grinding wheel (due to the bigger diameter)increasing the cutting speed (chip section gets smaller).reducing the cutting depth.Selection : Jot comment for selection:The cutter has a hardness of 61 HRC. Here you should use a grinding wheel sof

21、ter than Jot.For the selection however, measure and form precision have to be taken into consideration.Soft grinding wheels wear out faster. And so it is more difficult to keep the given form and measure tolerances.Structure (space portion of grains, bonding material and pores)123456789 10 11 12 13

22、14IThe pores are necessary as chip sections. Their size and quantity have also influence on the hardness (see above). A wheel being too tight is too hard and has too low efficiency.With a wheel being too open, it might be difficult do get a certain surface quality.As characteristic for the structure

23、 a number is used.Selection: structure 5Bonding (material, which binds the grains)The bonding is also responsible for the hardness and especially for the elasticity of the grindingwheel. The bonding has to endure a mechanical and also a very high thermal loading. In the following there are mentioned

24、 2 important groups:kind of bonding CharacteristicsCeramic Bondings VArtificial res inBondingsBgood hardness graduation possibilities resistance against water and oilindifference to high heating, butsensitivity to impactsmuch more elastic than ceramic bondings (especially important for thin grinding

25、 wheels)By the elastic attitude the grains areprotected against overload.Selection: V (Ceramic Bonding)The standard designation of the chosen grinding wheel is:Grinding wheel DIN69120*250*25*76A60Jot5VCheck and dressing of the grinding wheels, rules for prevention of accidents During grinding the da

26、nger of accidents is very high. When the grinding wheel breaks, the parts flying around may cause a deadly accident, if they are not caught by a protecting device. The following rules for prevention of accidents are also including the field of free form grinding, (grinding of knifes, scissors, etc.)

27、Before dressing the grinding wheel you have first to effect an acoustic test. The wheel has to be kept in the bore and is slightly hit for ex. with a piece of hard wood. The sound must be high.The flanges must have the correct size (S1/3 D when using protective caps, S=2/3 D without protective caps,

28、 S=1 12 D for conical wheels. The flanges must have the same size. You must put intermediate layers out of elastic material between the abrasive wheels and the clamping flanges (for ex. rubber or felt). Thus irregularities on the grinding wheel surface shall be compensated.The grinding wheel must be

29、 easy to slip on the spindle.When you have simple grinding machines, the work rests have to be put close to the grinding wheel and have to be readjusted regularly.Please pay attention to the maximum rotation frequency. On the grinding wheel you can see the maximum allowable peripheral speed, for ex.

30、 on a blue stripe (blue: vc45m/s).Before the first start please take care that no tools or other things may be acquired by the grinding wheel.After each new setting you have to effect a test running of at least five minutes with the rated maximum rotating frequency.During grinding you have to wear p

31、rotective goggles.BalancingDuring grinding you work with high peripheral speeds and therefore also with high rotating frequencies. When using unbalanced grinding wheels, you have to expect unbalance and the corresponding centrifugal force. Unbalanced grinding wheels cause vibrations, which may impai

32、r the surface quality and reduce the life endurance of the grinding wheel and the machine.SAACKE Workshop GrindincThe grinding wheels have to be balanced together with their flanges. In many cases static balancing with compensation masses is sufficient. The grinding wheel satisfies in each position

33、the mass point. If there are high demands resp. very large wheels, you have to balance dynamically.Cylindrical grinding surface cylindrical grindingThe stud 025mm of the bevel pinion has a length of 20,3mm. If you have a grinding wheel width of 25mm it is possible to finish the diameter with one plu

34、nge-cut.This working method is called cross grinding.Due to the short production cycle it is very economical.After grinding the diameter, the endface has to be machined.This process is effected with the front face of the grinding wheel. By beveling it is possible to machine both surfaces in the same

35、 time with one plunge-cut.When you have big series cross - resp. profile grinding is effected.With this method a certain contour is completed by one plunge-cut.For longer parts you need either a longitudinal feed (swing grinding) or several plunge-cuts are placed side by side. The first possibility

36、you find more often, for ex. because by this method you can reach a continuous chip removal, the production time is reduced.For the swing grinding the grinding wheel has to have a littleoverrun (1/3 to 1/4 of the wheel width). If not, at the ends it will not be polished enough.For the bearing diamet

37、er 40 mm of the drive gear wheel the following shift is necessary:L =L+1/3 *BL : shift lengthI: pin length at theL = 54 mm + 1/3 *25 mm work piece (54mm)L 63 mmB : grinding wheel-width (25mm)During grinding the grinding wheel may be approached very sensitively; the scale division value amounts mostl

38、y to 1 pm. For automatic approach a margin (by a mechanical device) is possible.However, after deactivation of the feed the wheel continues grinding outsparking.That way the respect of the measure tolerances is very difficult. A measure control terminates the grinding process as soon as the required

39、 measure is reached.Centerless surface cylindrical grinding. The specialty of this method is that the work piece is not fixed in a clamping device, but lies free on a hard rest.A regulating wheel supports the work piece, in the same time the wheel transfers its peripheral speed on the work piece and

40、 enables so the grinding process.Plane or surface grindingFor the grinding of plane surfaces there exist parallels to milling. However the considerations of the milling cannot simply be transferred, because the tool has another structure and because you work with other speeds.During the face grindin

41、g there is a big contact area between the grinding wheel and the work piece surface. There are the following dangers:Intense heat generation (due to the big contact area). For hardened pieces the start temperature can be exceeded locally. That means: soft areas are generated.On a closed front face t

42、he chips and also the broken out grains have difficulties to come out. The wheel can be closed from the chips.1 Gecar Schle ctietbe2sg川淪lur Plynschlrf3 TCxem* xjm Scgrfxvcdon g” Wcrk?.t?jutn4 Tnpfsorwiifin zykndrBxh und& ochk;Possible counter measures are the following:Discontinuities in the grindin

43、g wheels (forex, segmental wheels).In some cases it is possible to incline the spindle. Hereby however there are form deviations at the work piece.The machining of the discontinued surfaces is favorable.Hereby the grains again and again hit free spaces, where the chips are kicked off and where is no friction. Also the single edges can “re-touch”.During periphery grinding the contact area between grinding wheel and work piece is relatively small. Therefore the metho