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C620 机械 加工 工艺 夹具 设计

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C620托脚机械加工工艺及钻35孔夹具设计,C620,机械,加工,工艺,夹具,设计

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晋中学院机械学院毕业设计任务书毕业设计题目：C620托脚机械加工工艺及夹具设计毕业设计要求及原始数据（资料）：要求：1.零件机械加工工艺规程设计2.夹具设计的加工内容-加工35H7孔原始资料:毕业设计（论文）主要内容：1.机床的选择 根据给定的零件，通过分析比较拟定加工机床。2.夹具的选择 根据给定的零件，通过分析比较拟定夹具装置机构方案。3.刀具的选择 根据给定的条件，通过分析比较拟定刀具选择方案。4.零件机械加工工艺规程设计。5.夹具的三维造型设计。6.编写设计说明书：查阅有关外文文献资料，并翻译成5千字以上。撰写毕业设计说明书1.5万字以上，其内容包括零件的分析，毛坯的确定，工艺方案的选定与比较，机床与切削用量的选取，时间定额的计算，夹具的设计及定位误差分析与定位误差的计算，夹紧力的估算等。学生应交出的设计文件：1.图纸（1）装配图1张，夹具非标准零件图1套。（2）零件机械加工工艺过程卡1张。（3）零件的加工工序卡2张。（4）被加工零件图1张。（5）夹具的三维造型装配图1张。2.说明书（1）设计说明书有说服力。（2）计算部分须指出公式来源并说明公式中符号所代表的意义，计算结果要准确。（3）设计说明书叙述要有条理，要分章节段落，用词要通顺简练，书写要工整。所有图表线图简图应画的正确。（4）设计说明书总量不少于1.5万字。主要参考文献（资料）：1 大连理工大学工程图学教研室. 机械制图（第7版）M.北京:高等出版社,2013.2 陈立德.机械制造技术基础课程设计M.北京:高等教育出版社,2009.3 尹成湖,等.机械制造技术基础M.北京:高等教育出版社,2009.4 闻邦春.机械设计手册（第5版）S.北京:机械工业出版社,2009.5 教育部高等教育司.高等学校毕业设计（论文）指导手册S.北京:高等教育出版社,2008.6 吴宗泽.机械零件设计手册S. 北京:机械工业出版社,2004.7 尹成湖,等.机械制造技术基础课程设计M.北京:高等教育出版社,2009.8 现代实用机床设计手册编委会.现代实用机床设计手册:上册,下册S.北京：机械工业出版社,2006.专 业 班 级 学 生 指导教师签字 日 期 教 研 室 主 任 签 字 日 期 Dec 2014机床与液压Hydromechatronics EngineeringVol 42No 24eceived: 2014 07 15* Project supported by the Government in Chongqing BananDistrict and Chongqing University of Technology SpecialProgram ( Item Number: 2012Q123) Tie- zhong XIAO，E- mail: 593712861 qq comDOI: 10 3969/j issn 10013881 2014 24 023Design and study on special fixture for finishing cylindercrankshaft hole*Tie- zhong XIAO1，Xuan LI2，Juan HUANG1，Jing LUO3，Chun- ying YUAN41Sichuan Engineering Technical College，Deyang 618000，China2Baotou Huihong Technology Engineering Co Ltd， Baotou 014030，China3Key Laboratory of Manufacture Techniques for Automobile Parts Ministry of Education，Chongqing University of Technology，Chongqing 400054，China4Guizhou Jonyang Kinetics Co ，Ltd，Guiyang 550006，ChinaAbstract: Since the precision of finishing operations for crankshaft hole will directly affect the qual-ity and life of the engine，an advanced and reasonable fixture system is very important for themachining accuracy According to the precision requirement of cylinder crankshaft hole in the realapplications，the process parameters and the positioning reference were determined in this pa-per，and the main structure of fixture system was designed and analyzed including the positioningmechanism，cutter relieving mechanism，clamping mechanism and boring mold Finally，the dy-namic characteristics of the boring bar were analyzed，and the effect of bearing stiffness on thedynamic characteristics of the boring bar was studied as well By appropriately increasing thebearing preload，i e ，bearing stiffness，the stiffness of the boring bar system could be effective-ly increased Based on the practical process inspection，the correctness of the design has beentested and verifiedKey words:Crankshaft hole，Special fixture，Boring bar，Dynamic characteristicsSince the processing requirements of engine arerelatively high，while crankshaft hole machining isone of the three key processes for the engine，and itsaccuracy will directly determine the overall perform-ance of the engine 1 ，an advanced and reasonablefixture system is very important for the machiningprecision and production efficiency 2- 3 Accordingto the current status of processing engine crankshafthole，the first approach is that rough，semi- finishingand finishing processes will be separated on a dedica-ted machine，and then three times different positio-ning clamping are required Since the clamping er-rors will inevitably exist，the final positioning accura-cy will be influenced，then the requirements of preci-sion machining can not usually meet;another disad-vantage is that the finishing process is usually com-pleted at the precision machining centers，which of-ten has high machining precision and low productionefficiencyIn order to solve the above- mentionedproblems，this paper will concentrate on the study ofcrankshaft hole semi- finishing and finishing in aprocess，i e ，a special fixture will be designed andthe semi- finishing and finishing of crankshaft holewill be completed by a single setup Therefore，itwill not only improve the machining accuracy and re-duce labor intensity，but also meet the requirementsof mass production efficiency1 Workpiece accuracy requirements anddetermined processes1 1 Workpiece parameters and accuracy require-mentsThe main parameters of the workpiece and accu-racy requirements is as follows:Name:Q465 cylin-der;Dimensions:311 298 223;Bore diameter:5 54+ 0 0240;Workpiece material:HT250 ( crankhole cover) ，aluminum alloy ( crankshaft hole basebody) ;Hardness:HB170 241 ( cast iron) ;work-piece weight: 30 kg As shown in Figure 1，the pro-cessing content and the accuracy requirements arepresentedFigure 1 Technical drawings1 2 To determine the processBoring operation is generally used to make thecrankshaft hole In this paper， since the rough boringprocess of workpiece has been completed，a specialfixture is adopted by a single setup to accomplish thesemi- fine boring and fine boring process of crankshafthole 4 Semi- fine boring and fine boring processesuse the CBN tools;cutting speed is 120 m/min，andboring spindle speed is 708 r/min;tool feed speed is0 06 mm/r;semi- fine boring unilateral margin is0. 5，and fine boring single unilateral margin is 0 1;cycle time is 2 3 min/piece 5 1 3 To determine the DatumCylinder bore rough boring and fine boringprocesses，which are ahead of boring crankshaft holeprocess，use bottom surface and craft pin hole for po-sitioning Cylinder bore honing process，which is be-hind of boring crankshaft hole process，also use bot-tom surface and craft pin hole for positioning Follow-ing the above- mentioned benchmark principles，thisprocess also uses the same methods to determine thebottom surface and locate the pin hole Following thedatum principles，this boring process also use thebottom surface and craft pin hole for positioning Asshown in Figure 2，it presents the process locatingdatum The bottom surface of the cylinder body isused as the first locating datum;craft pin hole nearthe rear end of the cylinder body is used as the sec-ond datum，and locating dowel pin is short cylindri-cal;craft pin hole near the front of the cylinder bodyis used as a third datum，and locating dowel pin isshort argyle 6 7 Figure 2 Locating datum schematic diagram2 Design of special fixture systemFixture system consists of specific folder，boringmold and other components，as shown in Figure 31 specific folder; 2， 11 adjustable fine- tune support block; 3，10 dowel pin; 4 Mechanism elevating cylinder; 5， 8 Clampingcylinder; 6， 9 Clamping block; 7 cylinder bodyFigure 3 Fixture schematic diagram2 1 Design of positioning mechanismPositioning method:two side pins;positioningprinciple:six positioning;locating pin programs:fixed the positioning pins The positioning mechanismis shown in Figure 3 Adjustable fine- tune supportblocks 2， 11 and dowel pins of 3 and 10 consisted oftwo side pins positioning mechanismDue to the manufacture accuracy，there is a gap811Hydromechatronics Engineeringbetween craft hole and dowel pin Therefore，the po-sitioning mechanism has a positioning error， as shownin Figure 4Figure 4 Positioning error Schematic diagramAfter positioning，the maximum angle error ofworkpiece could be evaluated by Eq ( 1) = arctan1 + 2L( 1)Where，1 is the largest gap between locationcenter of cylindrical pin and location center of crafthole;2 is the largest gap between location center ofthe argyle pin and location center of craft hole;1 +2 is the value of displacement error;L is the dis-tance between cylindrical pin and argyle pin All thevalues of 1，2 and L could be measured actually2 2 Clamping mechanismThis design used pneumatic clamping After theworkpiece is accurately positioned，the appropriateclamping force will be selected to overcome the vibra-tion and overturn torque generated during cuttingThe clamping mechanism is shown in Figure 5 Oncethe workpiece is accurately positioned，the pneumaticcylinder 1， 7 will push the clamping rod 3， 9 andclamping plates 5， 11 to clamp the workpiece drivenby guide bar 4， 101， 7 pneumatic cylinder; 2， 8 guide sleeve; 3， 9 Clampingrod; 4，10 guide bar;5， 11 clamping plates;6，12 clam-ping soft boardFigure 5 Clamping mechanism2 3 Boring moldAs shown in Figure 6，the boring mode structureis presented1 boring bar; 2， 4， 5， 7 angular contact ballbearings; 3， 6 boring sleeveFigure 6 Boring mode structureBoring mode structure is the external roll struc-ture，and there exists an axial relative movement andno relative rotation between the boring bar and boringsleeve Outside the boring sleeve，there equippedwith angular contact ball bearings，and the boringsleeve will rotate with the boring bar When the ma-chine is working，work federate of boring bar is low，and there only exist relative movement between theboring sleeve and the boring bar，and then boring barwill not be heated due to the rapid friction，so it willnot appear “killed”phenomenon of boring bar sys-tem Angular contact ball bearings are necessarilypreloaded，support stiffness throughout the boring barwill be greatly improvedThere is relative movement between the boringbar and boring sleeve，i e ，a gap exits betweenthem This gap will lead radial movement of boringbar in the boring process，then affect processingroundness and cylindrical If the gap is too big，pro-cessing precision may fail to meet the requirements;if the gap is too small，there may result in“killed”boring bar due to high- speed rotation boring sleeve inthe process Therefore，the gap between the boringbar and boring sleeve needs to be chosen as a reason-able valueIn fine boring process，the minimumclearance value between the straight boring bar andthe boring sleeve is recommended as from 1/5 to 1/6of the corresponding processing site tolerances Themaximum gap should be less than 1/3 of the corre-sponding processing site tolerances 8 3 Boring bar system analysis3 1 Boring bar modal analysisThe geometrical model and mesh are shown inFigure 7 In order to solve this problem，the modelhas to be simplified and some assumptions will bemade as follow:small structures such as chamfer andhelical surfaces will be ignored，and clearance grooveis treated as an entity;single row angular contact ball911Tie- zhong XIAO，et al:Design and study on special fixture forfinishing cylinder crankshaft holebearings are set as only bear radial load，and thisball bearings are simplified into springs;the densityof boring sleeve and boring bar is set to be the same，and boring sleeve is treated as additional distributionquality of boring bar;spindle speed is low，the bear-ing stiffness is treated as a constantBoundary conditions are set as follows:zero dis-placement constraints are the only load in modal anal-ysis，and the results are shown in Figure 8Figure 7 Finite element mesh model of boring barFigure 8 Modal analysisFormer sixth- order natural frequencies and cor-responding mode shapes of boring bar are shown inTable 1，in which it shows that the minimum naturalfrequency of the boring bar is 370 5 Hz that is muchgreater than the excitation frequency 11 8 Hz duringspindle operation Therefore，the resonance phenom-enon will not be generatedTable 1 Boring bar natural frequenciesand mode shapesOrderFrequency/HzMode shapes1370526 1translational motionand bending in the YZ plane2443528 4warping in the YZ plane3565805 1bending in the XZ plane4605591 0bending in the YZ plane5645352 3distortion in the XZ plane ( right)6668448 1distortion in the XZ plane ( left)3 2 Calculate bearing stiffnessIn this paper，the experience of the formula thatLin Song summed up in 1982 is used to calculate thestiffness of angular contact ball bearingK0= 0 39F1/3rd0 463 8( 3)Where，K0is zero clearance angular contact bearingstiffness ( N/m) ;Fris the bearing radial load( N) ;d is the bearing diameter ( mm) The selectedbearing model is 7014AC/P4，d =70 mm;load Fr=200 N By using Eq ( 3) ，the stiffness of angularcontact ball bearing could be calculated， K0=16 362 N/m，and for double support structure，thecorresponding bearing stiffness is 32 724 N/mwhich is as much as twice of K03 3 Effect of bearing stiffness on the boring barBearing stiffness is not a fixed value，and it hasa non- linear relationship with suffered load and pre-load The arrangement of angular contact ball bearingis constant，and bearing stiffness values are taken as0 327 24， 3 272 4， 32 724， 327 24， 3 272 4， 32724 N/m，respectively The first natural frequencyof boring bar variation is shown in Figure 9Figure 9 Effect of bearing stiffness onthe boring bar stiffnessAs shown in Figure 9，the natural frequency ofthe boring bar system gets increased with the increaseof bearing stiffness When bearing stiffness reaches acertain value，the natural frequency of the boring barsystem will approach to a certain value It could beseen that the bearing stiffness has an important influ-ence on the dynamic properties of boring bar systemTherefore，it is very important to obtain the rightbearing stiffness by adjusting the bearing preload inreal applications4 ConclusionIn this paper，a special fixture system is suc-021Hydromechatronics Engineeringcessfully developed，which will effectively improvethe machining accuracy and production efficiencyThrough the actual operation and test，the accuracyof machining tools meets or exceeds the expected re-quirements，and the production efficiency is up to 23 min/pc Furthermore，due to the high automationdegree of this fixture system， the labor intensity couldbe greatly reduced Currently，this technology hasbeen applied in multiple production lines of a numberof machinery manufacturing companies in Chongqing，and obtained some good feedbackseferences 1 Li Wen- di，Wang He- zeng，Yang Hong- mei Develop-ment of NC Machine for Finish Milling Cylinder Bottom Drilling and eaming Pin Hole J Modular MachineTool Automatic Manufacturing Technique， 2013( 6) :124- 129 2 Wu Min，Zhuang Dong- hai Technical Processing Analy-sis and Special Fixture Design Based on Panel Parts J MACHINE TOOL HYDAULICS， 2013( 8) : 43- 46 3Liu Xu， Zhu Xue- chao，Li Hong- wei Machining Tech-niques ules and Drilling Fixture Design on Typical ShellParts J Coal Mine Machinery， 2012( 8) : 125- 126 4 Luo Jing; Xiao Ti