0161-升降式路边停车系统机械部分的设计
0161-升降式路边停车系统机械部分的设计,升降,路边,停车,泊车,系统,机械,部分,部份,设计
刀具和刀夹想顺利的加工工件,就必须做到:1 刀具或刀片的种类要恰当。2 刀夹的类型要合适。3 刀具的切削刃要锋利。4 刀具要安装或调整到适当的位置和高度。刀具的材料制造车床上使用的刀片的基本材料有以下六种:水淬硬化钢,高速钢,硬铸有色合金,烧结硬质合金,陶瓷和金刚石。使用材料的选择取决于许多因素:刀具成本,刃磨费用,刀具的尺寸和类型,金属切削速率,使用时间的长短,零件的光洁度和公差,以及机床的条件和性能。由于有着许多因素,选择材料常常是根据一般的经验而不是精确计算。然而,对各种不同刀具材料的某些一般特性是应该有所了解的。水淬硬化钢 这一类包括高碳工具钢(即普通碳钢或加入了少量铬,钒或钨的碳钢)。在美国钢铁协会的分类制中,把各种钢号的水淬工具钢都归为W钢。用这种材料制造的刀具经过适当的热处理,其切削刃便非常锋利,光滑。它们适用于切削速度较低的有限车削,或使用于老式的,低转速设备,如平皮带车床上。用水淬工具钢制造的刀具其主要的缺点是在刃磨或切削时,切削刃温度如果超过华氏300400度,刀具就会软化。另一个缺点是刃口的耐磨性很低。高速钢高速钢在切削效率方面同水淬工具钢相比有很大的改进。用高速钢制成的刀具甚至当刀具温度达到华氏1050度时,还能保持足够的硬度进行高速切削。即使热的变成暗红色,它们还能使用。冷却至室温后,这种钢原来的硬度也不改变。高速钢的抗磨性比碳钢或合金钢的抗磨性要好的多,这是由于它的含碳量高,尤其在合金成分较高的高速钢里更是如此。高速钢由于充分淬火,比碳钢或硬铸合金有更高的抗冲击强度。美国钢铁协会分类制规定的有两种主要的高速钢,一种是M钢,一种是T钢。可以买到由这些材料制成的,刃磨成各种形状的刀条。未经刃磨的刀条叫做刀坯,也是可以购买到的。这类刀坯都制成标准尺寸以适应普通车床使用。常见的尺寸是3/16英寸见方乘1英寸,1/4英寸见方乘2英寸长,5/16英寸见方乘2。5英寸长,和3/8英寸见方乘3英寸长。高速钢刀条是校办机加工车间里最常见的。硬铸合金这类材料不含有足够的铁,因而不能算作钢。相反它们主要是钴,铬,钨和为了特殊用途而加一些其它元素的合金。它们在铸造状态下,不用热处理,即可达到充分的硬度。它们在铸造后,必须磨削至应有的尺寸。就其耐热性,耐磨性,抗冲击性几生产成本而言,铸合金可排在高速钢和硬质合金之间。硬铸合金的抗拉强度比较差而且比高速钢更脆,因而不适用于强烈的冲击载荷。它们在商业上的名称是司太立钨铬钴合金,锐克斯钨铬钴合金和坦塔钨铬钴合金。烧结硬质合金要进行高效和高速车削,使用烧结硬质刀片形状合金刀可以得到最佳效果。市场上买到的硬质合金有的做成整体形状,有的做成刀片形状焊接在刀杆上,或着我卡紧在刀杆上。装卡的刀片其形状通常是圆的,方的或三角行的,它上面所有的切削刃都是预磨好的。这类刀片能够转动,所以随时可得到锋利的切削刃。使用现代化的机床和级别适当的烧结硬质合金刀有可能采用比高速钢车刀要快1030倍的切削速度。硬质合金刀适用于大多数的机加工作业,如单刀刃车削,钻削,洗削,螺纹车削和铰削。只有当硬质合金刀能夹持得很牢固而且机床具有合适的功率与转速使其能发挥有效作用时才应采用硬质合金刀。金属陶瓷除了工业用金刚石以外,金属陶瓷刀片是现有的最硬,最强有力的刀片。他们抗磨损,抗碎裂,抗断折。这类刀片用在刚性良好的床子上,对夹持牢固的工件能发挥最好的作用。在大多数加工情况下,不需要切削液。金刚石当需要极高质量的表面光洁度时,可采用工业用金刚石作精加工。这种金刚石具有圆形或小平面的切削刃。尽管使用别种刀具材料能取得很光滑的光洁度,但金刚石车削可在公差很小的情况下,提供更加光滑的光洁度。刀夹刀夹在切削加工时可使刀具夹持牢固。常用的夹具有以下四种:1 带有标准刀夹的刀架刀架由支架,螺杆,垫圈,套圈,调整垫板组成。垫圈嵌在上滑块槽内。套圈和调整垫板可是刀尖上升或下降。螺杆则将刀夹固定就位。高速工具刀条的标准刀夹有三种常见的形状:直刀夹,右偏刀夹和左偏刀夹。用手拿住固定螺钉的一端 ,便可判断刀夹是右偏还是左偏。如果刀把偏向右,就是右偏刀夹。如果刀把偏向左,便是左偏刀夹。 直刀夹可用于大多数加工活儿。当需要接近卡盘或鸡心夹卡箍进行切削时,便可使 用左偏夹。右便刀夹是当朝着尾架方向进给时使用的。在这三种刀夹上,刀条均以14到16。5的角度固定。这便是所谓刀夹角度。硬质合金刀头的刀夹也有三种形式,在外表面上与上述高速钢的刀夹类似。但是夹持刀片的孔和刀夹的底边是平行的。2 开口刀架或称重型刀架一次可以夹持一把刀,它上面有一个带T形槽的压板,一个C型块,和两个或多个刀具价紧螺丝。因为这种装置非常牢靠,它尤其适用于重切削。刀条可以直接装卡于这种刀架内,也可以使用某种类型的硬质合金刀夹。3 转塔刀架或称方刀架有一回转块,车刀可以装于其中。常见的转塔刀架可以装四把刀。每把刀都能很快地回转至切削位置并价紧。某些转塔架具有八个刀位。通常,为了增加一个附加的加工工序,可在横向流板的后部安装一开口型刀架。采用这种安排,可装上59把不同类型的刀具,就可以按顺序对重复型零件进行车外圆,成形,车端面,滚花和切断等工序。4 速换型刀具系统一次只夹持一把刀具,但它的三个不同的侧边均可以用来装置刀具。它有一个带夹紧杆的快速换刀架,可安装一系列的刀夹作车外圆,车端面,镗孔,切断,攻丝,滚花和车螺纹。单刃切削刀具刀具的各个部分在认磨刀条之前,必须熟悉表明刀具各不同部分的一些术语1顶面 是刀条的顶部,它是当切削的一部分从工件上切下时刀条被切下的这一部分切屑所紧贴着的那个表面。2切削刃是刀条实际进行切削的那一部分。3刀尖是侧切刃和端切刃所形成的夹角或圆弧。4侧面是切削刃以下的表面。5刀头是刀片上构成切削刃和顶面的那一部分。刀具的角度用于一切单刃切削刀具的重要刀具角度如下:1 横向后角是刃磨表面和刀条在刃磨之前的垂直侧边之间的夹角。这个角度以前叫横向隙角,现在许多机工仍然采用这个术语。横向后角是工件的切削表面和刀具侧面之间的隙角。刀具的磨损会使有效横向隙角变小,如果这个交度太小,刀具就会摩擦,生热。如果这个角度太大,切削刃就会变钝,而刀具就易扎进工件里。2 纵向后角是切削刃末端和一垂直线之间的形成的夹角。以前这个角叫前向隙角。纵向后角是工件的已加工表面和刀具之间的间隙。如果这个角度太小,刀具将在已加工表面上摩擦从而产生不良的表面光洁度。磨损会使这一角度变小。如果着这一角度太大,刀具可能扎进工件,引起颤动,并由于崩刃而无法切削。对于钢制刀具,这一角度建议采用815度,硬质合金刀具建议用68度。如果刀具安装的高于旋转中心,就会使有效隙角变小。在选择合适的角度时,必须考虑到这一点。3 端刃角是刀具和工件已加工表面之间的夹角。如果这个角太小,就会造成颤动。然而为了形成光滑的表面光洁度,在精加工时,采用大约6度的小角度是合适的。4 侧刃角可将切屑从已加工表面卷走。角度最好在515渡之间。5 刀尖半径可使刀具不致有脆弱的尖角,可以延长刀具的寿命并改进表面光洁度。对于高强度的粗切刀,半径可大一些,而对于轻量进给则可以小一些。只要没有颤动产生,刀尖半径越大,光洁度就越好。对于精加工,刀尖半径建议采用0。010到0。030英寸或更大,对于粗加工是1/32到1/2英寸。6 为了有助于形成切削刃和顶面,必须在刀条上刃磨出两个前角来。从垂直面或水平面上倾斜就形成前角。当刀条顶面是平的或水平是,它没有前角。这两个前角就是纵向前角和横向前角/纵向前角,在向侧面单刃进给时,可将切削从已加工的工件上卷走,同时使刀具有一种切片的作用。纵向前角为零时,易形成蜗旋形切削,而当纵向前角大于零时,它易于使蜗旋形切削伸展为螺旋形切屑/使用515度的纵向前角可防止切削刮到工件上。高速钢刀条通常都刃磨成正前角。然而硬质合金刀具可能具有正的或负的前角。负前角可使形成切削的剪角增大,造成良好的表面光洁度。负前角刀具一般可在高速,大走刀的重型车床上使用。横向前角指的是刀具的顶面和刀具刃磨前从摸端看过去代表其顶部的那根线之间的夹角。横向前角可控制机加工时所产生的切屑的形状以及切屑的移动方向。横向前角小的刀具比前角大的刀具所产生的切屑要短一些。7 刀尖角是侧切刃和端切刃之间的夹角。单刃切削刀具的分类为了进行某些机加工工序需要不同形状的刀条,大多数刀条都刃磨成只朝一个方向切削。其常见的类型现在叫做有切刀和左切刀。以前叫做右偏刀和左偏刀。右切单刃刀是一种当顶面朝上,从刀尖方向看过去切削刃的右边的刀具。这种刀条装在车床上,它的切削刃就在左边。这种刀条是从右向左,即从尾架那一端朝车床的床头方向切削的。左切刀是当顶面朝上,从刀尖方向看过去切削刃在左边的刀具。这种刀具都刃磨成从左向右切削的,即朝车床的尾架方向切削的。常用的刀条类型有以下几种:1 粗车刀是一种用来进行重切削,把工件直径切至接近尺寸的刀具。因为在粗 加工时,表面光洁度是不重要的,这样的刀条可以刃磨成几乎是锋利的到尖。不过,这样的刀尖通常要稍微磨成圆弧状以防止崩刀。2 精车刀有磨的很锋利的切削刃,这种切削刃经油石研磨可产生非常光滑的光洁度。精车刀通常具有比粗车刀更大的圆弧尖。3 圆头刀是一种可以用于多种类型的通用刀具。当顶部磨平时,它既能用于右切也能用于左切,还能车削黄铜。它也可以用来在轴肩角处切削半径。圆头刀可用来作精车刀具。4 方头刀只用于工件末端的切削。它用来倒角和粗车以加工方形肩。5 切断刀只用于工件末端的切削,可用来切断装卡在卡盘上的棒料或工件。6 端面偏刀即通常所谓的偏刀,用来把工件的端部精车成与母线成直角的光滑的端面。右切端面偏刀总是用语精车轴的端部。左切端面偏刀可以用来精车轴肩的左侧。断屑槽为了解决切屑延续不断的这一难题,常常可以在高速钢刀尖上刃磨出一个断屑槽。断屑槽能够在一般磨刀砂轮上刃磨出来,而槽形的断屑槽则能由一个装在平面磨床上的薄砂轮刃磨出来。另一种单独的断屑器常用于装卡式硬质合金刀上。切削作用当车床车削时,有三个基本切削力,即:工件的纵向力,作用于刀具的侧面;工件的径向力,作用于刀具的前端;工件的切向力,作用于刀具的顶部。其中切向力比其他两个力要大的多,它对切削作用的影响也最大。这一巨大的作用力是加在切削刃上的。在大型金属切削机床上的测量表明,每平方英尺上的压力可达到25万磅。假如刀具形状不合适或装卡角度不合适,刀具很快就会变钝。在车床上切削时,就会从正在加工的材料上挤下片状的切屑。即连续的金属带。在软的,韧性材料上,这种楔挤作用是连续进行的。再较硬的材料上,楔挤力使金属受压缩。压缩一直延续到剪断为至。于是被挤压的金属就与工件脱离。在切削加工中始终重复这一过程。刀具的形状比切削刃的实际锋利程度更加重要的多。刀具没有后角就会使刀具在工件上磨蹭。这样加大了对切削刃的压力,从而影响刀具的性能。后角太大会使刀具脆弱无力,不能很好支撑切削刃。这样刀口就会迅速折断或磨损。刃磨高速工具钢刀条1 使刀具具有锐利的切削刃。2 使刀条为特定的工序提供正确的或最好的形状。3 使刀条的前端留有隙角。4 使刀条的侧面留有隙角。5 使切屑能在刀条顶面顺利滑过,并脱离切削刃。刃磨右切圆刀头的正确程序如下:1 检查砂轮,看砂轮表面是否修整好。再不平的或有沟的砂轮上刃磨出好的切削刃是困难的。应在刃磨切削刀具的专用台式磨床或立式砂轮机上进行刃磨。在这种砂轮机的一边应安装一个氧化铝粗砂轮另一边装一个细砂轮。使用粗砂轮把刀条粗磨成一定的形状。然后用细砂轮精磨刀条。2 刀具砂轮机应具有刃磨支架,把双手搁在支架上,以控制刀条的运动。握紧刀条,使它不能在砂轮上跳动。但不要握的太紧,以致难于移动刀条。3 手握刀条在砂轮上刃磨出横向后角,以便磨成侧刃角。这个角度在切削软钢时应大约6度。手握刀条贴在砂轮上,使刀条底部向内倾斜即可得到这种角度。当刃磨时,应将刀条在砂轮面上横向来回移动,而不改变其位置。这有利于较快的磨好刀条并防止在砂轮上磨出沟槽来。当刀条发热时就把它浸在水里使其冷却。初学者经犯上下移动的错误。这会在刀条侧面形成许多不同的角度,从而使它变的形状怪异。要避免出现这种情况,就应该使刀条固定在砂轮的一个位置上。要来回移动而决不要上下移动。4 在对侧刃磨出横向后角以把刀条磨成应有的形状。5 刃磨纵向后角,要握着刀使端部向上。成半圆形地摆动刀柄。力图使端部圆弧与两侧均匀的光滑的连接起来。在刃磨刀片的圆弧时,一定要减轻压力。不做到这一点,磨出的圆头刀就会大于所要求的形状。6 刃磨右切刀的横向前角,应使刀条的顶面即顶部与砂轮的右侧成直角。使刀片底部向内倾斜。使刀具保持这一位置,直到砂轮将整个顶面磨到切削刃时为止/刃磨左切刀的横向前角。要用手握住刀条于砂轮左侧。让刀条底部向内倾斜。让砂轮将整个顶面磨至切削刃。没有理由在刀条前端刃磨低于刀柄的顶面。这样会浪费昂贵的刀条并使刀具外形受到损害。7 用油石研磨精加工的刀条是一个很好的习惯。选择一个中细的油石。再油石上蘸一点煤油或猪油。使切削刃在油石上来回磨动。一定要把刀条拿平,以便不致使它的各种角度有任何改变。只要稍加实践,就能够正确的刃磨刀条。记住,一个磨得很好的刀条应具有恰当的 刀具角度和磨的很匀称的平整表面。车床的维护在任何时候都要保持车床的清洁和润滑良好。同任何精密机械一样,车床也要认真维护。只要操作者对床子进行恰当的维护,它就能运转正常,加工精确。不要犯依赖别人给床子加油和维修的错误。操作者的人身安全取决于他保持床子安全运转的能力。车床的正常维护包括清理,加油,调整和小修等工作。清理车床在每一个工作日后要彻底清理车床。如果切屑和脏物留在导轨,传动装置和其它运行部件上时,它的表面就会变粗糙并出现凹坑。这会导致迅速磨损以致使这些部件难于操纵。建议按下述步骤清理车床:先用刷子扫除全部切屑。注意 大部分切屑锋利如刀,因此决不可以用手去清理。用一把2英寸的漆刷或小台刷来清理切屑是方便的。这时应把尾架移到床身的右端。1 用一块干净的布或棉丝擦拭所有的油漆表面。否则留在油漆表面的油迹会变硬和污染油漆。2 用同样的布或棉丝擦去所有机加工表面的油污和油脂。3 刷掉切屑盘里所有的切屑,然后把它擦干净。4 在安装卡盘以前,先用一铁丝作成的螺纹清除器将其内螺纹清除干净。再把主轴螺纹擦拭干净。滴上一,两滴油。5 把顶尖锥柄装入主轴孔之前,先把主轴孔和顶尖锥柄擦拭干净。如果顶尖锥柄上有毛刺或粗糙的疵点,在装入主轴孔之前,要用挫或油石将毛刺或粗糙疵点除掉。6 有时,可用一根绳来擦拭丝杠上的螺纹槽。把绳绕在丝杠上。调整传动位置,使丝杠以中速转动。开动车床,随着丝杠的转动,当绳子沿着丝杠螺纹往前走时,来回拉动绳子。7 当给车床加油时,要擦拭掉任何可能益处和滴在油漆表面上的油。8 开始工作前,一定要确保在导轨上保持有一层薄薄的油膜。9 调整横向进给和复合流板的镶条螺钉,以消除部件之间的松动状态即间隙。如果用手握住刀架并来回晃动就能使横向进给移动,这就说明。镶条螺钉太松了。调整每个镶条螺钉,直到横向进给手柄得到平滑运动为止。当螺钉调整好以后,推拉倒架就不可能使横向进给移动。10 决不要把刀具或工件放在车床导轨上。这样做就会损坏经过精密刮研的表面精度/可把工具放在车床的木板上。11 当使用刀架磨头时,一定要保护车床的机加工表面,要把它们覆盖起来。如果在磨削加工时这些表面没有覆盖好,从砂轮上掉下来的沙砾就会嵌入支撑面,从而很快破坏车床的精度。12 每星期一次,用蘸有煤油的干净布,把车床整个擦拭一遍。先擦干净油漆表面,然后擦机加工表面。擦干后就在所有的加工表面薄薄的涂上一层清洁的油。车床的加油和润滑车床的恰当润滑是很重要的。每台车床都带有一张润滑图。所使用的润滑油和润滑脂的等级,品种一定要符合图中的要求。要养成每天开始工作之前给车床加油的习惯。有些部件要每天加油。另一些部件按图表规定要每周或每月加油一次。几个人使用同一台车床,常常是人人相互依赖,结果是没人给机床加油和维护。CUTTING TOOLS AND TOOLHOLDERSTo machine a workpiece successfully you must have :1. the correct kind of cutting tool or tool bit 2. the right type of toolholder3. a tool with a sharp cutting-edge4. the cutting tool set or adjusted to the correct height and position.Cutting-tool materialsTool bits used on the lathe are made form one of six basic materials: water-hardening steels,high-speed steels,hard-cast,nonferrous alloys,sintered (cemented) carbides,ceramics,and diamonds. The selection of the material used depends upon many factors including:tool cost,size and design of tool ,metal-removal rate ,length of run ,finish and tolerance of part,and condition and capability of the machine tool . Because of these factors ,material selection is more often based on general experience than on precise evaluation . There are, however ,certain general characteristics of the different cutting-tool materials you should understand.Water-hardening Steels.These include the high-carbon tool steels (either plain carbon or those with minor additions of chromium , vanadium,or tungsten) .The different grades of water-hardening tool steels are classed as W steels in American Iron and Steel Institutes system of classification . Tools made from these materials have very sharp ,smooth cutting-edges when properly heat-treated. They are adequate for limited turning at a relatively low cutting speed or when old ,low-speed equipment ,such as a flat-belt lathe , is used .The main limitation of tools made form water-hardening steels is that they soften if the cutting-edge temperature exceeds approximately 300-400F during sharpening or cutting .A second disadvantage is low resistance to edge wear .High-speed Steels. High-speed steels offer great improvement in cutting efficiency over water-hardening tool steels .Tools made from high-speed steels retain enough hardness to machine at rapid rates even when the tool temperature reaches 1050F . They can be used even though they become dull red with heat . Upon cooling to room temperature , the original hardness of these steels does not change . Wear resistance of high-speed steels is much better than that of the carbon or alloy steels . This is due to the high carbide content ,especially in the higher-alloy types of high-speed steel . Fully hardened , high-speed steels have greater resistance to shock than carbides or hard-cast alloys .There are two main types of high-speed steels designated in the American Iron and Steels Institute system , M steels (molybdenum base and T steels tungsten base . Tool bits made from these materials can be purchased already ground to various shapes . Unground tool bits called tool-bit blanks can also be purchased . These tool-bit blanks are made in standard size to fit the commonly used lathes . The common sizes are 3/16in square by 1 in long ,1/4in square by 2in long ,5/16in square by 2-1/2in long ,and 3/8in square by 3in long . High-speed steel tool bits are the type most used in the school machine shop . Hard-cast Alloy . These materials do not contain sufficient iron to be classed as steels . Rather , they are mainly alloys of cobalt , chromium , and tungsten with other elements added for special purpose . They reach full hardness in the as-cast condition , without heat treatment . The must be ground to size after casting . In terms of resistance to heat , wear ,shock ,and initial cost , cast alloys rank between high-speed steels and carbides . Hard-cast alloys are weaker in tension and more brittle than high-speed steels and thus are not suitable for severe shock loads . They are known by such commercial names as stellite , Rex alloy ,and tantung .Sintered Carbides . For efficient and high-speed machining ,best results can be obtained with sintered carbide tools . Carbide tools are available in solid form and as inserts which are either brazed or clamped in toolholders . Clamped inserts are usually round , square , or triangular in shape and have all edge is always available . These inserts can be rotated so that a sharp edge is always available . With modern machine tools and the proper grade of cemented carbide , it is possible to use cutting speeds 10 to 30 time faster than those feasible with high-speed steels . Carbides are suitable for most machining operations such as single-point turning , drilling ,milling , thread cutting, and reaming . Carbides should be used only when they can be supported rigidly and when the machine tool has adequate power and speed to enable their efficient use . Ceramic . With the exception of industrial diamonds , ceramic inserts are the hardest and strongest inserts available . They resist abrasive wear , chipping , and breakage . These inserts work best on very rigid machine tools and on well-supported workpieces . For most operations , cutting fluids are not needed . Diamonds . Industrial diamonds that have either circular or faceted cutting-edges are used for light finishing cuts when an extremely high-quality surface finish required . Although a very smooth finish can be achieved using other cutting-tool materials , diamond turning can provide even smoother finishes with very small tolerances .TOOLHOLDERSThe toolholder holds the cutting tool rigid during cutting operations . Four types of toolholders are in general use . 1 . The tool post with standard toolholders . The tool too post is comprised of the post , screw , washer , collar , and rocker . The washer fits the top slidee piece slot . The collar and the rocker elevate or lower the point of too . The screw clamps the toolholder in place . The standard toolholder for high-speed steel cutter bits comes in three common shapes : straight , right-hand offset or shank , and left-hand offset or shank . You can identify right-hand and left-hand offset holders by holding the setscrew end in your hand . If the shank bends to the right , it is a left-hand offset holder .The straight toolholder is fused for most work . The left-hand toolholder is used when you need to cut close to the chuck or lathe dog . The right-hand holder is used when feeding toward the tailstock of the lathe . The cutting-tool bit is held in each of these toolholders at an angle of 14 to 16.5 degrees . This is called the toolholder angle . Carbide toolholders also come in three styles and are similar in appearance to those mentioned above . The hole for the cutter bit , however , is parallel to the bottom edge of the holder . 2. The open-side or heavy-duty tool block holds one tool at a time and consists of a T-slot clamp , a C-shaped block , and two or more tool clamping screws . Because this unit is very rigid , it is especially useful for heavy cuts . A tool bit can be mounted directly in the tool block or some type of carbide tooolholder can be used . 3. The turret tool block or four-way toolholder consists of a swiveling block in which the tools are clamped Common turret block hold four tools . Each can be quickly swiveled into cutting position and clamped in place . Some turret blocks have eight tool stations . Frequently ,an open-side-type tool block is also mounted on the rear of the cross slide to add one additional cutting operation . With this arrangement , anywhere form five to nine different kinds of tools can be mounted and operated in sequence for turning , forming ,facing ,knurling , and cutting off duplicate parts . 4. The quick-change-type tool system holds only one tool at a time , but three different sides can be used to position the tool . It consists of a quick-change tool post with a clamping lever and a series of toolholders for turning , facing , boring , cutting off , threading , knurling , and thread cutting .Single-point Cutting Tools Tool Parts . Before you can grind a tool bit , you must become acquainted with some of the terms used to describe the various parts of the cutting tool . 1 . The face is the top of the tool bit . It is the surface on which a part of the chip attaches as it is cut away form the workpiece .2. The cutting-edge is that part of the cutter bit which actually does the cutting .3. The nose is the corner or are formed by the side and end cutting-edge . 4. The flank is the surface below the cutting-edge . 5. The point is the part of the tool bit which is shaped to form the cutting-edge and face . Tool Angles .The following are important tool angles used for all single-point cutting tools .1. The side relief angle is the angle between the ground surface and the vertical side of the tool bit before it is ground . This angle was formerly called side clearance , and many machinists still use this term .The side relief angle provides clearance between the cut surface of the work and the flank of tool . Tool wear reduces the effective side clearance angle .If the angle is too small, the cutter will rub and heat . If the angle is too large , the cutting-edge will be weak and the tool will have a tendency to dig into the workpiece.2. The end relief angle is the angle formed between the end of the cutting-edge and a vertical line. It was formerly called front clearance. The end relief angle provides clearance between the finished surface of the work and the tool. If this angle is too small, the tool will rub on the finished surface and produce a poor finish. Wear tends to reduce this angle. If the angle is too large , the tool may dig into the work , chatter, and fail through chipping . An angle of 8 to 15 is recommened for steel tools and 6 to 8 for carbide tools .If the tool is set above the center of rotation , the effective clearance angle is reduce . This must be considered in choosing the proper angle . 3. The end cutting-edge angle provides clearance between the cutter and the finished surface of the work .If this angle is too small, it may cause chatter. A small angle of about 6 is desirable on light finishing cuts, however, in order to produce a smooth finish . 4. The side cutting-edge angle turns the chip away form the finished surface .Recommended angles are between 5 and 15 .5. The nose radius removes the fragile corner of the tool , prolongs tool life , and improves finish . The radius may be large for maximum-strength rough-cutting tools and may be reduced for light feeds . The larger the nose radius ,the better the finish as long as chatter dose not occur .Recommended nose radii are 0.010 to 0.030 in . or more for finishing cuts , and 1/30 to 1/2 in for roughing cuts . 6. To help shape the cutting-edge and face , it is necessary to grind rake angles on a tool bit .Rake is an inclination form the vertical or horizontal .The two rake angles are back rake and side rake . Back rake , in a single-point feeding to the side , turns the chip away form the finished work and gives the tool a slicing action .A zero back rack tends to make a spiral chip , and a back rake angle greater than zero tends to stretch the spiral chip out into a helix . A back-rake angle of form 5 to 15 is used to keep chips form scratching the workpiece . High-speed steel tool bits are always ground with a positive rake .However , cemented carbide tools may have either a positive or negative rake .Negative rake increases the shear angle at which the chip is formed , providing for a good chip and a good surface finish .Negative rake tools are generally used on a heavy-duty lathe that is operated at high speed with a heavy feed . Side rake refers to the angle between the face of the tool and a line that would represent the top of the unground tool bit as viewed form the end . Side rake controls the type of chip produced during machining as well as the direction in which the chip will travel .A tool with a small side-rake angle will produce shorter chips than one with a large rake angle .7 .The nose angle is the angle between the side-cutting edge and the end-cutting edge .Classes of Single-point Tools Different shapes of tool bits are needed to do certain machining operations . Most tool bits are ground to cut in one direction only .The two common types are referred to as right cut and left cut .These were formerly called right-hand and left-hand tool bits .A right-cut single-point tool is one that , when viewed form the point end with the face up , has its cutting-edge on the right side .When the tool bits is placed in the lathe , the cutting-edge is on the left side .This tool bit cuts form the right to the left , or form the tailstock end toward the headstock of the lathe .A left-cut tool bit has the cutting-edge on the left when viewed form the point end with the face up . This tool bit is ground to cut form the left to the right or toward the tailstock of the lathe .Commonly used types of tool bits include the following:1. A roughing tool is a tool bit designed to take heavy roughing cuts to reduce the diameter of a workpiece to approximate size . Because finish is not important when roughing work , such a tool bit may be ground to almost a sharp point . However , the point is usually rounded very slightly to prevent its breaking down . 2. A finishing tool i
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