调速杠杆(135调速器)的机械工艺规程和夹具设计【镗孔夹具】【含CAD图纸、说明书】
【温馨提示】压缩包内含CAD图有下方大图片预览,下拉即可直观呈现眼前查看、尽收眼底纵观。打包内容里dwg后缀的文件为CAD图,可编辑,无水印,高清图,压缩包内文档可直接点开预览,需要原稿请自助充值下载,所见才能所得,请见压缩包内的文件及下方预览,请细心查看有疑问可以咨询QQ:11970985或197216396
压缩包内含有CAD图纸和说明书,咨询Q 197216396 或 11970985 机械制造技术基础课程设计说明书设计题目 设计“调速杠杆(135调速器)”零件的机械加工工艺及工艺设备设 计 者 班 级 学 号 指导教师 机械制造工艺学课程设计任务书题目: 调速杠杆的机械加工工艺规则及工艺装备内容:1.零件图 1张 2.毛坯图 1张 3. 机械加工工艺过程综合卡片 1张 4. 结构设计装配图 1张 5. 结构设计零件图 1张 6. 课程设计说明书 1张一、序言机械制造工艺学课程设计使我们学完了大学的全部基础课、技术基础课以及大部分专业课之后进行的.这是我们在进行毕业设计之前对所学各课程的一次深入的综合性的总复习,也是一次理论联系实际的训练,因此,它在我们四年的大学生活中占有重要的地位。就我个人而言,我希望能通过这次课程设计对自己未来将从事的工作进行一次适应性训练,从中锻炼自己分析问题、解决问题的能力。由于能力所限,设计尚有许多不足之处,恳请各位老师给予指导。二、零件的工艺分析(一)、零件的作用题目所给的零件是调速杠杆,主要作用是用于连接调速器,对侧面加工要求低,对下孔的的加工精度要求比较高,尤其是12mm的孔有粗糙度的要求高,加工有困难但是毛坯直接铸造出,可降低难度。零件图及零件的三维图分别如图1和图2。 图一零件图 图 二 立体图(二)、零件的工艺分析通过对该零件的重新绘制,知道图样的视图正确,完整尺寸,公差及技术要求齐全。但下表面的精度较高。要进行精铣才能达到粗糙度要求。 该零件属于杆类零件,它的侧面都是直接铸造出来的,在加工时很方便,但要同时保证孔的平行度和同轴度比较困难,但毛坯基本确定位置,所以简单了许多(三)、零件的生产类型 零件为成批及大批量生产,毛坯铸造出来。三、工艺规程设计(一)、确定毛坯的制造形式零件材料为30钢,考虑零件结构比较简单,但形状结构比较复杂,故选择铸件毛坯。(二)、基面的选择 基面选择是工艺规程设计中的重要工作之一。基面选择得正确与合理可以使加工质量得到保证,生产率得以提高。否则,加工工艺过程中会问题百出,更有甚者,还会造成零件的大批报废,是生产无法正常进行。(1)、粗基准的选择。对于零件而言,尽可能选择不加工表面为粗基准。而对有若干个不加工表面的工件,则应以与加工表面要求相对位置精度较高的不加工表面作粗基准。根据这个基准选择原则,现选杠杆的下表面为粗基准,利用定位销定位。(2)、精基准的选择。主要应该考虑基准重合的问题。当设计基准与工序基准不重合时,应该进行尺寸换算,这在以后还要专门计算,此处不再重复。(三)、制定工艺路线 制定工艺路线得出发点,应当是使零件的几何形状、尺寸精度及位置精度等技术要求能得到合理的保证,在生产纲领已确定的情况下,可以考虑采用万能性机床配以专用夹具,并尽量使工序集中来提高生产率。除此之外,还应当考虑经济效果,以便使生产成本尽量下降。 工艺路线方案:工序一:先铸件回火工序二:以下表面定位,粗铣上表面工序三:以上表面定位,粗铣下表面工序四:以外圆面和下端面定位,粗镗6mm的圆和8的圆工序六:粗镗半精镗和精镗6mm,在粗镗半精镗和精镗8mm的内孔, 工序七: 以下端面和加工好的孔定位粗加工12内孔工序八:半精铰工12 ,精铰工12内孔工序八:以12内孔和外圆面定位铣槽工序九:加工各倒 工序十:去毛刺,检验四、机械加工余量、工序尺寸及毛皮尺寸的确定(一)、毛胚的基本尺寸确定:杠杆零件材料为30钢,硬度187217HB,生产批量成批及大批量,铸造毛坯。查铸件尺寸公差与机械加工余量确定步骤如下1.求最大轮廓尺寸 根据零件图计算轮廓尺寸,长158.5mm,宽16mm,高9mm。故最大轮廓尺寸为158.5mm.。2.选取公差等级CT 由表5-1 铸造方法按机器造型,铸件材料按铸铁得公差等级CT范围8-12级,取9级3. 求铸件尺寸公差 根据加工面的基本尺寸和铸件公差等级CT,由表5-3得,公差带相对于基本尺寸对称分布。4求机械加工余量等级 由表5-5知铸铁用砂型铸造机器造型和壳体的方法选得机械加工余量等级E-G级,取为F级。5求RMA,对所有加工表面取同一个数值,由表5-4查最大轮廓尺寸为158.5mm,机械加工余量等级为F级,得RMA数值为1.5 mm6求毛坯基本尺寸: 底面为单侧加工,算得:R= F+RMA+CT/2=9+21.5+3=15,圆整为15mm。(二)、各工序之间的加工余量及公差:1、粗铣下表面的加工余量及公差工序名称工序间余量/mm工序间工序间尺寸/ mm工序间经济精度/mm表面粗糙度/mm尺寸、公差/mm表面粗糙度/m粗铣31125990.0512.5铸造0.4150.402、粗铣上表面的加工余量及公差工序名称工序间余量/mm工序间工序间尺寸/ mm工序间经济精度/mm表面粗糙度/mm尺寸、公差/mm表面粗糙度/m粗铣31125990.0512.5铸造0.415150.43、 钻孔、粗铰6孔的加工余量及公差工序名称工序间余量/mm工序间工序间尺寸/ mm工序间经济精度/mm表面粗糙度/mm尺寸、公差/mm表面粗糙度/m粗铰0.296.3666.3钻孔5.81212.512.5铸造04、钻孔、粗铰、精铰8孔的加工余量及公差工序名称工序间余量/mm工序间工序间尺寸/ mm工序间经济精度/mm表面粗糙度/mm尺寸、公差/mm表面粗糙度/m精铰0.0496.3886.3粗铰0.161012.57.960.1612.5钻孔7.81212.57.87.825铸造05、钻孔、粗铰、精铰12孔的加工余量及公差工序名称工序间余量/mm工序间工序间尺寸/ mm工序间经济精度/mm表面粗糙度/mm尺寸、公差/mm表面粗糙度/m精铰0.0573212123.2粗铰0.186.311.9511.956.3扩孔0.85106.311.8511.856.3钻孔111212.5111112.5铸造06.粗铣槽的加工余量及公差工序名称工序间余量/mm工序间工序间尺寸/ mm工序间经济精度/mm表面粗糙度/mm尺寸、公差/mm表面粗糙度/m粗铣20.51025202025粗铣1151025191925铸造1216167、粗镗12.5孔工序名称工序间余量/mm工序间工序间尺寸/ mm工序间经济精度/mm表面粗糙度/mm尺寸、公差/mm表面粗糙度/m粗镗0.25122512.512.525铸造712123. 其他尺寸直接铸造得到。 由于本设计规定的零件为大批量生产,应该采用调整加工。因此在计算最大、最小加工余量时应按调整法加工方式予以确认。五、确立切削量及基本工时工序一:热处理工序二:铣下表面:(1)粗铣加件工条工件材料:30钢,铸造。 加工要求:粗铣毛坯下端面。机床:X51立式铣床。刀具:W18Cr4V硬质合金钢端铣刀,牌号YG6。铣削宽度15=ae=9,深度ap=6,故据切削用量简明手册(后简称切削手册)取刀具直径do=10mm。选择刀具前角o5后角o8,副后角o=8,刀齿斜角s=10,主刃Kr=60,过渡刃Kr=30,副刃Kr=5过渡刃宽b=1mm, z=82. 切削用量1)铣削深度 因为切削量较小,故可以选择ap=2.0mm,二次走刀即可完成所需长度。2)每齿进给量 机床功率为4.5kw。查切削手册fz=0.140.24mm/z。由于是对称铣,选较小量fz=0.18mm/z。3)查后刀面最大磨损查切削手册表3.7,后刀面最大磨损为1.01.2mm。查切削手册表3.8,寿命及寿命T=180min4)计算切削速度 按切削手册,V c= 算得 Vc16.8m/min,n=50r/min,据XA6132铣床参数,选择nc=65r/min, ,则实际切削速度 Vc=3.14*10*65/1000=2m/min=0.03m/s, 实际进给量为0.03*8*65=15.6mm/min根据X51立式铣床工作台进给量表(表5-73)选择25mm/min则实际每齿进给量为f=15.6/8*60=0.03mm/z5)校验机床功率 根据机制指南表2-18,铣削时的功率(单位为Kw)为式中,30,1.0,则 189N, =0.03m/s,0.125 kw4.5 kw最终确定 ap=2.0mm,nc=65r/min,,V c=0.03m/s,f z=0.03mm/z6)计算基本工时。工序二 铣杠杆上端面。(1)粗铣加件工条工件材料:30钢,铸造。 加工要求:粗铣毛坯下端面。机床:X51立式铣床。刀具:W18Cr4V硬质合金钢端铣刀,牌号YG6。铣削宽度15=ae=9,深度ap=6,故据切削用量简明手册(后简称切削手册)取刀具直径do=10mm。选择刀具前角o5后角o8,副后角o=8,刀齿斜角s=10,主刃Kr=60,过渡刃Kr=30,副刃Kr=5过渡刃宽b=1mm, z=82. 切削用量1)铣削深度 因为切削量较小,故可以选择ap=2.0mm,二次走刀即可完成所需长度。2)每齿进给量 机床功率为4.5kw。查切削手册fz=0.140.24mm/z。由于是对称铣,选较小量fz=0.18mm/z。3)查后刀面最大磨损查切削手册表3.7,后刀面最大磨损为1.01.2mm。查切削手册表3.8,寿命及寿命T=180min4)计算切削速度 按切削手册,V c= 算得 Vc16.8m/min,n=50r/min,据XA6132铣床参数,选择nc=65r/min, ,则实际切削速度 Vc=3.14*10*65/1000=2m/min=0.03m/s, 实际进给量为0.03*8*65=15.6mm/min根据X51立式铣床工作台进给量表(表5-73)选择25mm/min则实际每齿进给量为f=15.6/8*60=0.03mm/z5)校验机床功率 根据机制指南表2-18,铣削时的功率(单位为Kw)为式中,30,1.0,则 189N, =0.03m/s,0.125 kw4.5 kw最终确定 ap=2.0mm,nc=65r/min,,V c=0.03m/s,f z=0.03mm/z6)计算基本工时。(1)粗铣工件材料:30钢加工要求:粗铣毛坯上端面。机床:X51立式铣床。刀具:W18Cr4V硬质合金钢端铣刀,牌号YG6。铣削宽度120=ae=90,深度ap=6,故据切削用量简明手册(后简称切削手册)取刀具直径do=160mm。选择刀具前角o5后角o8,副后角o=8,刀齿斜角s=10,主刃Kr=60,过渡刃Kr=30,副刃Kr=5过渡刃宽b=1mm, z=142. 切削用量1)铣削深度 因为切削量较小,故可以选择ap=2.0mm,一次走刀即可完成所需长度。2)每齿进给量 机床功率为4.5kw。查切削手册fz=0.140.24mm/z。由于是对称铣,选较小量fz=0.18mm/z。3)查后刀面最大磨损查切削手册表3.7,后刀面最大磨损为1.01.2mm。查切削手册表3.8,寿命及寿命T=180min4)计算切削速度 按切削手册,V c=算得 Vc28.8m/min,n=80r/min,据XA6132铣床参数,选择nc=80r/min, ,则实际切削速度 Vc=3.14*160*80/1000=40m/min=0.65m/s, 实际进给量为mm/min根据X51立式铣床工作台进给量表(表5-76)选择190mm/min则实际每齿进给量为mm/z5)校验机床功率 根据机制指南表2-18,铣削时的功率(单位为Kw)为式中,30,1.0,则 489 N, =0.65m/s,0.125 kw2mm/r, 按机床强度选择最终决定选择机床已有的进给量 经校验 校验成功。 (2)钻头磨钝标准及寿命后刀面最大磨损限度(查切)为0.81.2mm,寿命(3)切削速度查切 ,由于孔深与孔径比小于三,故不用乘以修正系数, =554.14r/min查切机床实际转速为故实际的切削速度vc=m/s=0.577m/s(4)校验扭矩功率 所以 故满足条件,校验成立。.计算工时由于所有工步所用工时很短,所以使得切削用量一致,以减少辅助时间。扩铰和精铰的切削用量如下:扩钻: d=7.96铰孔: do =8mm 工序五 钻、扩、铰M12的孔 加工条件:30钢,b=197217MPa,硬度190左右,铸件。 加工要求:钻、扩、铰M12孔 机床:Z550型立式钻床 1. 选择钻头 选择高速钢麻花钻钻头,粗钻时do=10mm,钻头采用双锥、修磨横刃、棱带磨法。后角o11,双重刃长度b=4.5mm横刃长b=2.5mm,弧面长度l=6mm,棱带长度 2.选择切削用量 (1)决定进给量查切 所以不用乘以修正系数, f=0.78-0.96mm/r 按钻头强度选择f2mm/r, 按机床强度选择最终决定选择机床已有的进给量 经校验 校验成功。 (2)钻头磨钝标准及寿命后刀面最大磨损限度(查切)为0.81.2mm,寿命(3)切削速度查切 ,由于孔深与孔径比小于三,故不用乘以修正系数, =577.2r/min查切机床实际转速为故实际的切削速度vc= 0.577m/s(4)校验扭矩功率 所以 故满足条件,校验成立。.计算工时由于所有工步所用工时很短,所以使得切削用量一致,以减少辅助时间。扩铰和精铰的切削用量如下:扩钻: d=11.85粗铰: d=11.95精铰: d=12do =12mm工序五 铣槽1. 粗铣加工条件机床:X51立式铣床。刀具:整体硬质合金直柄立铣刀,牌号YG6。齿数z=20,故据机制指南取刀具直径do=2.5mm。2. 切削用量1) 铣削深度 因为切削量较小,故可以选择ap=1.2mm,一次走刀即可完成。2) 每齿进给量 机床功率为2.8kw。查机制指南选f=0.008mm/z。查机制指南表5-148,后刀面最大磨损为0.300.50mm。查机制指南表5-149,寿命T=60minVc35.3m/min,n=225r/min,根据X51立式铣床参数,选择nc=200r/min,则实际切削速度V c=3.14*2.5*200/1000=31.4m/min=0.53m/s,工作台每分钟进给量为 mm/min2 半精铣加工条件机床:X51立式铣床。刀具:整体硬质合金直柄立铣刀,牌号YG6。齿数z=20,故据机制指南取刀具直径do=2.5mm。2. 切削用量1) 铣削深度 因为切削量较小,故可以选择ap=0.5mm,一次走刀即可完成。2) 每齿进给量 机床功率为2.8kw。查机制指南选f=0.008mm/z。查机制指南表5-148,后刀面最大磨损为0.300.50mm。查机制指南表5-149,寿命T=60minVc35.3m/min,n=321r/min,根据X51立式铣床参数,选择nc=320r/min,则实际切削速度V c=3.14*2.5*320/1000=42.8m/min工作台每分钟进给量为 mm/min六、 夹具设计总述:夹具设计是本次设计的主要部分,每个人都不同,下面就以镗孔为例说明设计的有关说明。 (1)定位方案 工件以一面两销定位可以限制工件的六个自由度,实现完全定位。定位可靠。 (2)夹紧机构 根据生产力的要求,直接用螺纹夹紧可以减少夹紧机构的大小。 (3)夹具与机床连接元件 采用两个销与机床相连,用于保证正确方向,并配合恰当。 (4)夹具体 工件与机床由连接件相连,连接件的要求比较高。 (5)结构特点 结构简单,操作方便。但也存在加工时的困难,这有带改进。(一) 问题的提出在本道工序中,6, 8, 12有粗糙度等级要求及公差要求。具体要求可以参见加工零件图纸。(二) 卡具设计1 定位基准的选择出于定位简单和快速的考虑,选择阀腔下表面为定位基准,即以一个面和两个定位销定位,限制六个自由度。2 切削力和卡紧力计算本步加工可按钻削估算卡紧力。实际效果可以保证可靠的卡紧。轴向力 扭矩 由于扭矩很小,计算时可忽略。卡紧力为取系数 S1=1.5 S2=S3=S4=1.1则实际卡紧力为 F=S1*S2*S3*S4*F=7.02N使用快速螺旋定位机构快速人工卡紧,调节卡紧力调节装置,即可指定可靠的卡紧力。3. 定位误差分析本工序采用三个定位销定位,是面定位。通过零件图纸我们可以知道,阀腔上表面的设计基准是下表面,那么设计基准与定位基准是重合的,故没有基准不重合误差,而且工件以平面定位是可以认为没有基准位移误差的。故本道工序的定位误差是可以忽略不计的。 所以D=0mm 4. 卡具设计及操作的简要说明卡具的卡紧力不大,故使用手动卡紧。在夹具的右边是用的两个单螺旋夹紧机构,左边是在一个凸台上安装两块衔铁来做为死挡铁来卡住工件。单螺旋机构是通过螺栓连接到夹具体上,同样凸台是通过螺钉连接到夹具体上。由于阀腔的定位面积比阀腔 上表面的面积小,而且阀腔的下表面有很大一部分的面积都未用做定位,故为防止工件在加工过程中出现不应该有的晃动或移动,故设计了一个辅助支承,这样就加强了零件的刚度,有利于保证加工精度。 七、设计小结机械制造工艺学课程设计使我们学完了大学的全部基础课、技术基础课以及大部分专业课之后进行的.这是我们在进行毕业设计之前对所学各课程的一次深入的综合性的总复习,也是一次理论联系实际的训练,因此,它在我们四年的大学生活中占有重要的地位。就我个人而言,我希望能通过这次课程设计对自己的四年的大学生活做出总结,同时为将来工作进行一次适应性训练,从中锻炼自己分析问题、解决问题的能力,为今后自己的研究生生活打下一个良好的基础。总的说来,虽然在这次设计中自己学到了很多的东西,取得一定的成绩,但同时也存在一定的不足和缺陷,我想这都是这次设计的价值所在,以后的日子以后自己应该更加努力认真,以冷静沉着的心态去办好每一件事情!八、参考书目:1:机械制造技术基础课程设计指南2:机械设计课程设计手册3:机制指南4:机械制造5:材料成型6:金属加工工艺设计 毕业设计(论文)外文资料翻译系 部:专 业:姓 名:学 号:(用外文写)外文出处: Design of machine elements 附 件:1.外文资料翻译译文;2.外文原文。 指导教师评语: 译文基本能翻译表达出原文的内容,条理较为分明,语句基本通顺,总体译文质量尚可,但少数专业术语翻译不够准确,一些语句比较生硬。 签名: 年 月 日附件1:外文资料翻译译文机器零件的设计相同的理论或方程可应用在一个一起的非常小的零件上,也可用在一个复杂的设备的大型相似件上,既然如此,毫无疑问,数学计算是绝对的和最终的。他们都符合不同的设想,这必须由工程量决定。有时,一台机器的零件全部计算仅仅是设计的一部分。零件的结构和尺寸通常根据实际考虑。另一方面,如果机器和昂贵,或者质量很重要,例如飞机,那么每一个零件都要设计计算。当然,设计计算的目的是试图预测零件的应力和变形,以保证其安全的带动负载,这是必要的,并且其也许影响到机器的最终寿命。当然,所有的计算依赖于这些结构材料通过试验测定的物理性能。国际上的设计方法试图通过从一些相对简单的而基本的实验中得到一些结果,这些试验,例如结构复杂的及现代机械设计到的电压、转矩和疲劳强度。另外,可以充分证明,一些细节,如表面粗糙度、圆角、开槽、制造公差和热处理都对机械零件的强度及使用寿命有影响。设计和构建布局要完全详细地说明每一个细节,并且对最终产品进行必要的测试。综上所述,机械设计是一个非常宽的工程技术领域。例如,从设计理念到设计分析的每一个阶段,制造,市场,销售。以下是机械设计的一般领域应考虑的主要方面的清单:最初的设计理念 受力分析 材料的选择 外形 制造 安全性 环境影响 可靠性及寿命在没有破坏的情况下,强度是抵抗引起应力和应变的一种量度。这些力可能是:渐变力 瞬时力 冲击力 不断变化的力 温差如果一个机器的关键件损坏,整个机器必须关闭,直到修理好为止。设计一台新机器时,关键件具有足够的抵抗破坏的能力是非常重要的。设计者应尽可能准确地确定所有的性质、大小、方向及作用点。机器设计不是这样,但精确的科学是这样,因此很难准确地确定所有力。另外,一种特殊材料的不同样本会显现出不同的性能,像抗负载、温度和其他外部条件。尽管如此,在机械设计中给予合理综合的设计计算是非常有用的。此外,显而易见的是一个知道零件是如何和为什么破坏的设计师可以设计出需要很少维修的可靠机器。有时,一次失败是严重的,例如高速行驶的汽车的轮胎爆裂。另一方面,失败未必是麻烦。例如,汽车的冷却系统的散热器皮带管松开。这种破坏的后果通常是损失一些散热片,可以探测并改正过来。零件负载类型是一个重要的标志。一般而言,变化的动负载比静负载会引起更大的差异。因此,疲劳强度必须符合。另一个关心的方面是这种材料是否直或易碎。例如有疲劳破坏的地方不易使用易碎的材料。一般的,设计师要靠考虑所有破坏情况,其包括以下方面:应力 应变 外形 腐蚀 震动 外部环境破坏 紧固件的松脱零件的尺寸和外形的选择也有很多因素。外部负荷的影响,如几何间断,由于轮廓而产生的残余应力和组合件干涉。材料的机械性能材料的机械性能可以被分成三个方面:物理性能,化学性能,机械性能。物理性能密度或比重、温度等可以归为这一类。化学性能这一种类包括很多化学性能。其中包括酸碱性、化学反应性、腐蚀性。其中最重要的是腐蚀性,在外行人看来,腐蚀性被解释为在某处的零件抵抗腐蚀的能力。机械性能机械性能包括拉伸性能、压缩性能、剪切性能、扭转性能、冲击性能、疲劳性能和蠕变。材料的拉伸强度可以通过试件的横截面积出试件承受的最大载荷得到,这是在拉伸试验中,应力沿Y轴,应边沿X轴变化的曲线。一种材料加载时开始发生变化的初值取决于负载的大小。当负载去掉时可以看到变形消失。对于很多材料而言,在达到弹性极限的一定应力值A之前,一直表现为这样。在应力-应变图中,这是可以用线性关系来描述的。这之后又一个小的偏移。 在弹性范围内,达到应力的极限之前,应力和应变是成比例的,这被称为比例极限Ap。在这个区域,零件符合胡克定律,即应力与应变是成比例的,在弹性范围内(材料能完全恢复到最初的尺寸,当负载去掉时)。曲线中的实际点,比例极限在弹性极限处。这可以认为是材料恢复初值时落后于前者。这种影响在不含铁的材料中经常提到。铁和镍有明显的弹性范围,而铜、锌、锡等,即使在相对低的应力下也表现为不完全弹性。实际上,能否清楚地分辩弹性极限和比例极限取决于测量设备的灵敏度。当负载超过弹性极限时,塑性变形开始,逐渐的试件被硬化。变形比负载增加得更快时的点被称成为屈服点Q。金属开始抵抗负载转变成快速变形,这时的屈服力成为屈服极限Ay。试件的延伸率 继续由Q到T再到,在这种塑性流动时,应力应变关系在曲线上处于QRST区域。在点,试件破坏且这种负载称为破坏负载。最大负载S除以试件初始的截面积,被定义为这种金属的最终拉伸极限或试样的拉伸强度Au。按逻辑说,在应力不增加的情况下,一旦超出弹性极限,金属开始屈服,并最终破坏。但是当超出弹性极限后,在纪录曲线上应增大。这种变化主要有两个原因:材料的应力硬化由于塑性变形而引起的试件横截面积的变小由于加工硬化,金属塑性变化越大,硬化越严重。金属拉伸越长,他的直径(横截面积)越小。直到到达点为止。点之后,减少的速率开始变化,超过了应力增加的速率,应变很大以至于在局部的某些点的面积减少,被称为颈缩。横截面积减少得非常快,以至于抗负载的能力下降,即ST阶段。破坏发生在T点。延伸率A和截面积变化率u被描述成材料的延展性和塑性:a=(L0-L)/L0*100%u=(A0-A)/A0*100%在这里,L0和L分别是试件的最初和最终长度,A0和A分别是试件的最初截面积和最终截面积。质量保证与控制 产品质量是生产中最重要的。如果放任质量恶化下去,生产者会很快发现销售量锐减,可能从而会导致产业的失败。用户期望他们买的产品质量性能好,而且如果制造商想建立并维持其信誉,必须在产品制造前制造过程中及制造过程后进行质量控制和质量保证。一般来说,质量保证包括所有的活动,其包括质量建立和质量控制。质量保证可以被分为三个主要领域,他们如下所述:制造之前的原材料的检查在制造加工过程中的质量控制制造之后的质量保证生产制造后的质量控制包括保证书和面对产品用户的服务。生产制造之前的原材料检验质量保证常常在实际生产制造之前就开始了。这些都是生产者在供应原材料、散件或配件的车间里进行检验。生产制造公司的原材料检验员到供应厂并且检查原材料及于制造的另配件。原材料检验为生产者提供了一次机会,那就是在原料及散件被运到生产车间之前先进行挑选淘汰。原料检察员的责任是去检查原料和零件是否达到设计规格并且淘汰那些未达到特殊指标的原料。原料检验有很多于检查产品相同的检验。其如下所述:目测冶金测试尺寸测试 损伤检验性能检验目测目测检验一种产品或原料的某些特征,如颜色、纹理、表面光洁度或部件的总体外观,从而判断其是否具有明显的缺损。冶金测试冶金测试常常是原料间严厉的一个很重要的部分,尤其是像棒料、建筑材料毛坯一些原材料。金属测试包含所有主要的检验类型,其中有目测,化学检验,光谱检验和机械性能检验,其包括硬度、伸缩性能、剪切性能、压缩性能和合成成分的光谱分析。冶金测试既可用于成品件也可用于预制件。尺寸检验质量控制的一些领域是重要的生产件的要求尺寸。尺寸在检验过程中,像其在生产过程中一样重要。如果这些零件是为总成供应的,那尺寸尤其严格。一些尺寸在生产车间用标准测量工具进行检验,像特种接头、造型和需求的功能标准度量。符合尺寸规格对所制造多部件的互换性和对多部件成功组装成复杂的装置,如汽车、轮船、飞机和其他多部件产品都地极其重要的。损伤检验在一些情况下,对原材料或零部件采取损伤测试的原始测验是很必要的。特别是涉及到大批的原材料时。例如,在被运到生产车间作最终机器之前,对铸件进行X-射线、电磁离子、染色渗透剂技术的探伤是很必要的,又对机器总成的电子或持久运作测试而确定的规格,是无损测试的又一例证。有时,对材料及零件的测试是很必要的,但由于无损测试的花费和成本及时间不是任何时候都允许的。例如,有压力测试决定在设计中其是否安全。损伤测试经常用于设计样机的测试,而不是原材料或零件的常规检验。一旦设计达到了所希望的材料强度,通常对零件做进一步的损伤测试是不必要的,除非他们确实存在疑点。 性能测试 性能测试在零部件被其他产品被安装之前,检查部件的功能,尤其是那些机械构造复杂的部件。例如电子设备零件,飞机和汽车发动机,泵、阀及其他需要在装运和最后安装前进行性能测验的机械系统。 附件2:外文原文(复印件)Design of machine elements The principles of design are, of course, universal. The same theory or equations may be applied to a very small part, as in an instrument, or, to a larger but similar part used in a piece of heavy equipment. In no ease, however, should mathematical calculations be looked upon as absolute and final. They are all subject to the accuracy of the various assumptions, which must necessarily be made in engineering work. Sometimes only a portion of the total number of parts in a machine are designed on the basis of analytic calculations. The form and size of the remaining parts are designed on the basis of analytic calculations. On the other hand, if the machine is very expensive, or if weight is a factor, as in airplanes, design computations may then be made for almost all the parts. The purpose of the design calculations is, of course, to attempt to predict the stress or deformation in the part in order that it may sagely carry the loads, which will be imposed on it, and that it may last for the expected life of the machine. All calculations are, of course, dependent on the physical properties of the construction materials as determined by laboratory tests. A rational method of design attempts to take the results of relatively simple and fundamental tests such as tension, compression, torsion, and fatigue and apply them to all the complicated and involved situations encountered in present-day machinery. In addition, it has been amply proved that such details as surface condition, fillets, notches, manufacturing tolerances, and heat treatment have a market effect on the strength and useful life of a machine part. The design and drafting departments must specify completely all such particulars, must specify completely all such particulars, and thus exercise the necessary close control over the finished product. As mentioned above, machine design is a vast field of engineering technology. As such, it begins with the conception of an idea and follows through the various phases of design analysis, manufacturing, marketing and consumerism. The following is a list of the major areas of consideration in the general field of machine design: Initial design conception; Strength analysis; Materials selection; Appearance; Manufacturing; Safety; Environment effects; Reliability and life; Strength is a measure of the ability to resist, without fails, forces which cause stresses and strains. The forces may be; Gradually applied; Suddenly applied; Applied under impact; Applied with continuous direction reversals; Applied at low or elevated temperatures. If a critical part of a machine fails, the whole machine must be shut down until a repair is made. Thus, when designing a new machine, it is extremely important that critical parts be made strong enough to prevent failure. The designer should determine as precisely as possible the nature, magnitude, direction and point of application of all forces. Machine design is mot, however, an exact science and it is, therefore, rarely possible to determine exactly all the applied forces. In addition, different samples of a specified material will exhibit somewhat different abilities to resist loads, temperatures and other environment conditions. In spite of this, design calculations based on appropriate assumptions are invaluable in the proper design of machine. Moreover, it is absolutely essential that a design engineer knows how and why parts fail so that reliable machines which require minimum maintenance can be designed. Sometimes, a failure can be serious, such as when a tire blows out on an automobile traveling at high speeds. On the other hand, a failure may be no more than a nuisance. An example is the loosening of the radiator hose in the automobile cooling system. The consequence of this latter failure is usually the loss of some radiator coolant, a condition which is readily detected and corrected. The type of load a part absorbs is just as significant as the magnitude. Generally speaking, dynamic loads with direction reversals cause greater difficulties than static loads and, therefore, fatigue strength must be considered. Another concern is whether the material is ductile or brittle. For example, brittle materials are considered to be unacceptable where fatigue is involved. In general, the design engineer must consider all possible modes of failure, which include the following: Stress; Deformation; Wear; Corrosion; Vibration; Environmental damage; Loosening of fastening devices. The part sizes and shapes selected must also take into account many dimensional factors which produce external load effects such as geometric discontinuities, residual stresses due to forming of desired contours, and the application of interference fit joint.Mechanical properties of materials The material properties can be classified into three major headings: (1) physical, (2) chemical, (3) mechanicalPhysical properties Density or specific gravity, moisture content, etc., can be classified under this category. Chemical propertiesMany chemical properties come under this category. These include acidity or alkalinity, react6ivity and corrosion. The most important of these is corrosion which can be explained in laymans terms as the resistance of the material to decay while in continuous use in a particular atmosphere. Mechanical properties Mechanical properties include in the strength properties like tensile, compression, shear, torsion, impact, fatigue and creep. The tensile strength of a material is obtained by dividing the maximum load, which the specimen bears by the area of cross-section of the specimen. This is a curve plotted between the stress along the This is a curve plotted between the stress along the Y-axis(ordinate) and the strain along the X-axis (abscissa) in a tensile test. A material tends to change or changes its dimensions when it is loaded, depending upon the magnitude of the load. When the load is removed it can be seen that the deformation disappears. For many materials this occurs op to a certain value of the stress called the elastic limit Ap. This is depicted by the straight line relationship and a small deviation thereafter, in the stress-strain curve (fig.3.1). Within the elastic range, the limiting value of the stress up to which the stress and strain are proportional, is called the limit of proportionality Ap. In this region, the metal obeys hookess law, which states that the stress is proportional to strain in the elastic range of loading, (the material completely regains its original dimensions after the load is removed). In the actual plotting of the curve, the proportionality limit is obtained at a slightly lower value of the load than the elastic limit. This may be attributed to the time-lagin the regaining of the original dimensions of the material. This effect is very frequently noticed in some non-ferrous metals. Which iron and nickel exhibit clear ranges of elasticity, copper, zinc, tin, are found to be imperfectly elastic even at relatively low values low values of stresses. Actually the elastic limit is distinguishable from the proportionality limit more clearly depending upon the sensitivity of the measuring instrument. When the load is increased beyond the elastic limit, plastic deformation starts. Simultaneously the specimen gets work-hardened. A point is reached when the deformation starts to occur more rapidly than the increasing load. This point is called they yield point Q. the metal which was resisting the load till then, starts to deform somewhat rapidly, i. e., yield. The yield stress is called yield limit Ay. The elongation of the specimen continues from Q to S and then to T. The stress-strain relation in this plastic flow period is indicated by the portion QRST of the curve. At the specimen breaks, and this load is called the breaking load. The value of the maximum load S divided by the original cross-sectional area of the specimen is referred to as the ultimate tensile strength of the metal or simply the tensile strength Au. Logically speaking, once the elastic limit is exceeded, the metal should start to yield, and finally break, without any increase in the value of stress. But the curve records an increased stress even after the elastic limit is exceeded. Two reasons can be given for this behavior: The strain hardening of the material; The diminishing cross-sectional area of the specimen, suffered on account of the plastic deformation. The more plastic deformation the metal undergoes, the harder it becomes, due to work-hardening. The more the metal gets elongated the more its diameter (and hence, cross-sectional area) is decreased. This continues until the point S is reached. After S, the rate at which the reduction in area takes place, exceeds the rate at which the stress increases. Strain becomes so high that the reduction in area begins to produce a localized effect at some point. This is called necking. Reduction in cross-sectional area takes place very rapidly; so rapidly that the load value actually drops. This is indicated by ST. failure occurs at this point T. Then percentage elongation A and reduction in reduction in area W indicate the ductility or plasticity of the material: A=(L-L0)/L0*100% W=(A0-A)/A0*100% Where L0 and L are the original and the final length of the specimen; A0 and A are the original and the final cross-section area.Quality assurance and control Product quality is of paramount importance in manufacturing. If quality is allowed deteriorate, then a manufacturer will soon find sales dropping off followed by a possible business failure. Customers expect quality in the products they buy, and if a manufacturer expects to establish and maintain a name in the business, quality control and assurance functions must be established and maintained before, throughout, and after the production process. Generally speaking, quality assurance encompasses all activities aimed at maintaining quality, including quality control. Quality assurance can be divided into three major areas. These include the following:Source and receiving inspection before manufacturing;In-process quality control during manufacturing;Quality assurance after manufacturing. Quality control after manufacture includes warranties and product service extended to the users of the product. Source and receiving inspection before manufacturing Quality assurance often begins ling before any actual manufacturing takes place. This may be done through source inspections conducted at the plants that supply materials, discrete parts, or subassemblies to manufacturer. The manufacturers source inspector travels to the supplier factory and inspects raw material or premanufactured parts and assemblies. Source inspections present an opportunity for the manufacturer to sort out and reject raw materials or parts before they are shipped to the manufacturers production facility. The responsibility of the source inspector is to check materials and parts against design specifications and to reject the item if specifications are not met. Source inspections may include many of the same inspections that will be used during production. Included in these are:Visual inspection;Metallurgical testing;Dimensional inspection;Destructive and nondestructive inspection;Performance inspection.Visual inspections Visual inspections examine a product or material for such specifications as color, texture, surface finish, or overall appearance of an assembly to determine if there are any obvious deletions of major parts or hardware. Metallurgical testing Metallurgical testing is often an important part of source inspection, especially if the primary raw material for manufacturing is stock metal such as bar stock or structural materials. Metals testing can involve all the major types of inspections including visual, chemical, spectrographic, and mechanical, which include hardness, tensile, shear, compression, and spectr5ographic analysis for alloy content. Metallurgical testing can be either destructive or nondestructive. Dimensional inspection Few areas of quality control are as important in manufactured products as dimensional requirements. Dimensions are as important in source inspection as they are in the manufacturing process. This is especially critical if the source supplies parts for an assembly. Dimensions are inspected at the source factory using standard measuring tools plus special fit, form, and function gages that may required. Meeting dimensional specifications is critical to interchangeability of manufactured parts and to the successful assembly of many parts into complex assemblies such as autos, ships, aircraft, and other multipart products. Destructive and nondestructive inspection In some cases it may be necessary for the source inspections to call for destructive or nondestructive tests on raw materials or p0arts and assemblies. This is particularly true when large amounts of stock raw materials are involved. For example it may be necessary to inspect castings for flaws by radiographic, magnetic particle, or dye penetrant techniques before they are shipped to the manufacturer for final machining. Specifications calling for burn-in time for electronics or endurance run tests for mechanical components are further examples of nondestructive tests. It is sometimes necessary to test material and parts to destruction, but because of the costs and time involved destructive testing is avoided whenever possible. Examples include pressure tests to determine if safety factors are adequate in the design. Destructive tests are probably more frequent in the testing of prototype designs than in routine inspection of raw material or parts. Once design specifications are known to be met in regard to the strength of materials, it is often not necessary to test further parts to destruction unless they are genuinely suspect. Performance inspection Performance inspections involve checking the function of assemblies, especially those of complex mechanical systems, prior to installation in other products. Examples include electronic equipment subcomponents, aircraft and auto engines, pumps, valves, and other mechanical systems requiring performance evaluation prior to their shipment and final installation.
收藏