华南理工机械制造基础试题与答案

1、机械制造技术根底试题 1班级 姓名学号成绩一、填空选择题30分1 .刀具后角是指.2 .衡量切削变形的方法有两种,当切削速度提升时,切削变形增加、减历 3 .精车铸铁时应选用YG3 YT10、YG8;粗车钢时,应选用YTS YG6 YT30.4 .当进给量增加时,切削力增加、减少 ,切削温度增加、减少.5 .粗磨时,应选择软、硬砂轮,精磨时应选择紧密、疏松组织砂轮.6 .合理的刀具耐用度包括 与 两种.7 .转位车刀的切削性能比焊接车刀好,差,粗加工孔时,应选择拉刀、麻花钻刀具.8 .机床型号由 与 按一定规律排列组成,其中符号C代表车床、钻床.9 .滚斜齿与滚直齿的区别在于多了一条范成运动、

2、附加运动传动链.滚齿时,刀具与工件之间的相对运动称成形运动、辅助运动.10 .进行精加工时,应选择水溶液,切削油,为改善切削加工性,对高碳钢材料应进行退火,淬火处理.11 .定位基准与工序基准不一致引起的定位误差称基准不重合、基准位置误差,工件以 平面定位时,可以不考虑基准不重合、基准位置误差.12 .机床制造误差是属于系统、随机误差,一般工艺水平系数G应不低于二级、三级.13 .在常用三种夹紧机构中,增力特性最好的是 机构,动作最快的是 14 . 一个浮动支承可以消除0、1、2个自由度,一个长的v型块可消除3,4,5个自由度.15 .工艺过程是指 8分、外圆车刀切削局部结构由哪些局部组成绘图

3、表示外圆车刀的六个根本角度.三、简述切削变形的变化规律,积屑瘤对变形有什么影响 8分四、CA6140车床主传动系统如下所示,试列出正向转动时主传动路线及计算出最高转速与 最低转速.8分五、什么叫刚度机床刚度曲线有什么特点 8分六、加工下述零件,以 B面定位,加工外表 A,保证尺寸10+.2mm试画出尺寸链并求出工 序尺寸L及公差.8分七、在一圆环形工件上铳键槽,用心轴定位,要求保证尺寸34.8- 0.16mm试计算定位误差并分析这种定位是否可行.8分八、试制定图示零件单件小批生产的工艺路线.12分0.03mm滚子,用抽样检验并计算得到全部工件的平0.08九、在六角自动车床上加工一批18均尺寸为

4、 17.979mm,均方根偏差为0.04mm,求尺寸分散范围与废品率.X X1.201.251.301.5F0.38490.39440.40320.4332试题1参考答案1.后刀面与切削平面间的夹角.2.变形系数与滑移系数,减少 3.YG3, YT54.增加,增加5. 软,紧密 6.Tc , Tp 7. 好,麻花钻8 .字母,数字,车床9.附加运动,成型运动10. 切削油,退火11.基准不重合,基准位置12. 系统,二级 13. 螺旋,圆偏心14.1,415.用机械加工方法直接改变原材料或毛坯的形状、尺寸和性能,使之成为合格零件的过程.外圆车刀的切削局部结构由前刀面、后刀面、付后刀面、主切削刃

5、、付切削刃与刀尖组成.六个根本角度是：ro、a o、kr、kr、入s、a o变形规律：roT, AhJ; VcT, AhJ; f T , Ah k HBf, AhJ积屑瘤高度HbT ,引起刀具前角增加,使AhJ四.最高转速约1400r/min ,最低转速约 10r/min五.刚度是指切削力在加工外表法向分力,Fr与法向的变形 Y的比值.机床刚度曲线特点：刚度曲线不是直线；加载与卸载曲线不重合；载荷去除后,变形恢复不到起点.六., 0L= 22 0.1mm七.A定=0.022mm,定位装置可行.八.工序1:粗车各外圆、端面、60圆孔；精车 200外圆与端面,精镶 60孔；精车96外圆、端面B与端

6、面C 车床工序2:插槽插床工序3:钻620孔钻床工序4:去毛刺钳工台九.尺寸分散范围：17.859 18.099mm废品率：17.3%机械制造技术根底试题 2班级 姓名学号成绩一、填空选择题30分1 .工序是指 O2 .剪切角增大,说明切削变形增大,减少；当切削速度提升时, 切削变形增大,减少.3 .当高速切削时,宜选用高速钢,硬质合金刀具；粗车钢时,应选用YTS YG6 YT30.4 . CA6140车床可加工 ： 甘四种螺纹.5 .不经修配与调整即能到达装配精度的方法称为互换法、选配法.6 .当主偏角增大时,刀具耐用度增加,减少,当切削温度提升时, 耐用度增加、减少.7 .在四种车刀中,转

7、位车刀的切削性能最好,最差 ；粗磨时应选择硬,软砂轮.8 .机床的根本参数包括、.9 .滚齿时,刀具与工件之间的相对运动称成形运动、辅助运动.滚斜齿与滚直齿的区别在于多了一条范成运动、附加运动传动链.10 .衡量已加工外表质量的指标有 O11 .定位基准面和定位元件制造误差引起的定位误差称基准不重合、基准位置误差,工 件以平面定位时,可以不考虑基准不重合、基准位置误差.12 .测量误差是属于系统、随机误差,对误差影响最大的方向称 方向.13 .夹紧力的方向应与切削力方向相同,相反 ,夹紧力的作用点应该靠近,远离工 件加工外表.14 .辅助支承可以消除0、1、2个自由度,限制同一自由度的定位称完

8、全定位、过定 位.15 .磨削加工时,应选择乳化液,切削油 ,为改善切削加工性,对不锈钢进行退火, 淬火处理.二、端面车刀的切削局部的结构由哪些局部组成绘图表示表示端面车刀的六个根本角度.8分三、金属切削过程的本质是什么如何减少金属切削变形 8分四、列出切削英制螺纹的运动方程式,并写出CA6140车床进给箱中增倍变速组的四种传动比.8分五、加工下述零件,要求保证孔的尺寸B= 30+,试画出尺寸链,并求工序尺寸L.8分0.016六、磨一批d= 12mmt肖轴,工件尺寸呈正态分布,工件的平均尺寸X= 11.974 ,均0.043方根偏差b= 0.005 ,请分析改工序的加工质量.如何加以改良. 8

9、分X X1.002.002.503.00F0.34130.47720.49380.4987七、滚斜齿时需要多少种运动列出每条运动链的首末端元件及计算位移.8分八、制订下述零件的机械加工工艺过程,具体条件：45钢,圆料 力70,单件生产.12分-I-1-其余九.在一杆状形工件铳键槽,要求保证尺寸50-0.2 mn# 34.8-0.16mm设计该工件的定位方案,并进行定位误差分析.10分试题2参考答案1. 一个工人在一台机床上对一个或多个零件所连续完成的那局部工艺过程.2.减少,减少 3.5.互换性6.8.尺寸,运动,动力 9.理机械性能11.13.相同,靠近 14.0硬质合金,YT5 4.减少,

10、减少7.成型运动,附加运动 10.基准位置,基准位置12.,过定位15.公制,英制,模数和径节最好,软外表层几何形状特征,外表层物随机,误差敏感乳化液,调质端面车刀切削局部结构由前刀面、后刀面、付后刀面、主切削刃,付切削刃与刀尖构成.端面车刀的六个根本角度：.、a o、kr、kr、入s、a o被切金属在刀刃的挤压作用下,产生剪切滑移变形,并转变为切屑的过程.要减少切削变形,可增大前角,提升速度,增大进给量,适当提升工件材料硬度.4.u1 = 18/45 X 15/48, u2=28/35 X 15/48 u3 = 18/45 X 35/28u4 = 28/35 X 35/285.0.04L=

11、60 0.08mm6.废品率等于2.28%,改良举措：将算术平均值移至公差带中央,即使砂轮向前移动A,A = 0.0035ms7.滚齿时需要四种运动：1 .主运动 电动机n电一滚刀n刀2 .范成运动 滚刀1/k r 工件1/Z k 3 .进给运动 工件1 r 刀架f4 .差动运动 刀架L 工件1 r 8.工序1 :粗测各外圆、端面、钻 14孔,精车 40外圆及端面；以 40为基准面,精键 30孔,精车 60及端面车床.工序2:铳键槽铳床工序3:钻46孔钻床工序4:去毛刺钳工台9.用V型块及支承钉定位,定位误差等于0.0034mm,符合要求,定位方案可行.机械制造技术根底试题 3班级姓名学号成绩

12、一、填空选择题30分1 .刀具前角是指 用符号 表示.2 .当工件材料硬度提升时,切削力增加,减少 ； 当切削速度提升时,切削变形增加、减少 .3 .制造复杂刀具宜选用高速钢、硬质合金；粗车钢时,应选用YTS YG6 YT30.4 .为改善切削加工性,对高碳钢采取淬火,退火处理；对不锈钢淬火,调质处理.5 .粗加工时应选择水溶液、切削油 ,粗磨时,应选择软、硬砂轮.6 .精基准的选择原那么是 o7,进给量越大,外表粗糙度愈高,愈低 ；精加工孔时,应选择拉刀、麻花钻刀具.8 .机床的运动按其功用可分为 与 两大类.9 .滚斜齿与滚直齿的区别在于多了一条范成运动、附加运动传动链.滚齿时,刀具与工件

13、之间的相对运动称成形运动、辅助运动 .10 .在CA6140车床上加工公制螺纹时,所用挂轮是63/100 X 100/75, 100/100 X 100/100 .11 .夹紧力作用点应靠近,远离工件的加工外表；工件以平面定位时,可以不考虑基 准不重合、基准位置误差.12 .完全互换法适用于 大量,单件生产,所有零件公差之和应大于,小于装配公差.13 .工艺系统刚度等于Fy/y , Fz/y ,工艺系统刚度大,误差复映大,小.14 . 一个支承钉可以消除0、1、2个自由度,消除六个自由度的定位称完全定位、过 定位.15 .生产类型通常分为 、三种.二、切断车刀切削局部结构由哪些局部组成绘图表示

14、切断车刀的六个根本角度.8分三、量度切削变形的方法有几种各有什么特点能否全面衡量金属切削过程的 物理本质 8分四、列出切削公制螺纹的运动方程式,并写出CA614眸床进给箱中根本变速组 的八种传动比.8分五、在热平衡条件下,磨一批 18-0.035的光轴,工件尺寸呈正态分布,现测得 平均尺寸X= 17.975,标准偏差7 = 0.01,试计算工件的分散尺寸范围与废 品率.8分X X1.002.002.503.00A0.34130.47720.49380.4987六、加工下述零件,以B面定位,加工外表A,保证尺寸10+0.2mm试画出尺 寸链并求出工序尺寸L及公差.8分 L .0.05七、指出以下

15、定位方案所消除的自由度.8分八、根据所学知识,列出提升零件加工质量的举措.九、图示拨叉零件,材料HT30Q单件小批生产1 .对零件进行工艺分析.2 .制订该零件的加工工艺过程.J- y rB p7y ； 史X.r: /、,.,一一1 /尸7 i vy /vivZ试题3参考答案10 分12分其余V|山二,司上 谭囱弋. . .-33.y口|4 15AQ 5|1.前刀卸与盘面的夹角ro)2.增加,减少3.高速钢,YT54.退火,调质5.水溶液,软6.基准重合、统一、自为、互为、可靠原那么7.愈高,拉刀8.成型运动,辅助运动9.附加运动,成型运动10.63/100X 100/7511.靠近,基准位置

16、12.大量,小于13.Fy/y,小14.1,完全定位15.单件,成批,大量生产2.切断车刀切削局部由前刀面、后刀面、付后刀面、主切削刃、付切削刃与刀尖组成.切断车刀的六个根本角度：ro、a o、kr、kr、入s、a o3.量度方法有两种：1.变形系数简单,直观但结果近似,从塑性压缩方面分析.2. 滑移系数复杂,结果较精确,从剪切变形考虑.两种方法都有片面性,不能全面反映金属切削过程的物理本质.4.u1 = 26/28u2 = 28/28u3 = 32/28u4 = 36/28u5 = 19/14u6 = 20/14u7 = 33/21u8 = 36/215.分散范围：17.945 18.005

17、mm,废品率为 6.2 %6.0.1L= 30 0.05mm7.x,y,z,y,z；y,zx ,y,z;x,y,z,x,y,z8.提升加工精度的举措：减少误差,误差补偿,误差分组,误差转移,就地加工,误差平均,误差限制.提升外表质量举措：采用合理的切削用量与刀具参数,采用冷压强化与光整工艺,采用良好的切削液,减少积屑瘤、鳞刺和震动.9.工序1:粗精铳尺寸40左右端面铳床工序2: 钻绞 24孔车床工序3:粗精铳尺寸12左右端面、R25圆弧面铳床工序4:钻攻M8螺纹孔钻床工序5:去毛刺钳工台 Manufacturing Engineering and Technology Machining Te

18、st Paper2004-06-17Name:Student No:Score:1 Drawing and marking (Close Test. 10 marks)1.1 Fig 1a) shows a turning tool. Please mark the tool angles (rake angle, cutting edge angle, tool cutting edge inclination angle and minor cutting edge angle) in Fig 1b). (5 marks)1.2 Pointing the process methods a

19、nd marking the main motions in Fig 2. (5 marks)2 Judging. Marking V for true and x for false. (Close Test. 30 marks, 2 marks for each)2.1 The built-up edge is one of the factors that most adversely affecting surface finish in cutting. (V)2.2 Whencontinuous chip are formed, the machine tool is easier

20、 to vibrate and chatter than the case in which discontinous chips are formed. (x )2.3 In turning the highest temperature is usually found in the middle of crater wear area rather than the tool corner. (V)2.4 Whenusing carbide inserts to hard turning, we should cool the cutting zone with cutting flui

21、d discontinously. (x)2.5 In surface grinding we should use oils as grinding fluids and in thread grinding we should use water-based emulsions. ( x )2.6 Indexable carbide inserts are usually brazed to the tool shank. (x )2.7 Diamond tools are usually used to finish-machining cast iron and steels. (x

22、)2.8 the most important limitation of high-speed steel is the cutting speeds thatcan be employed, which are low relative to those of carbide tools. (V)2.9 In a planer, the workpiece is mounted on a table that travels along a straight path; in a shaper, the tool travels along a straight path, and the

23、 workpiece is stationary. ( V)2.10 Three-jaw chucks have jaws that can be moved and adjusted independently of each other; they can be used for square or odd-shaped workpieces. (x )2.11 For drilling, reaming and tapping, blind holes must be drilled deeper than subsequent reaming or tapping operations

24、 that may be performed. (V)2.12 In conventional milling (up milling), the feed direction is same as the cutting direction. ( x)2.13 The broaching operation can be used to machine internal and external surfaces, such as holes of circular, square, keyways, and flat surfaces. (V)2.14 In gear hobing, th

25、e gear blank rotation is main cutting motion, while the hob rotation is feed motion. ( x )2.15 A hard grinding wheel means its abrasive particles have very high hardness.(X)3 Qualitative problems (Close Test. 20 marks, 4 marks for each)3.1 Why is it not always advisable to increase cutting speed in

26、order to increase production rate?Answer: Because cutting temperature will be obviously raised with the increase of cutting speed, which has a great and adverse influence on tool lifeso that we haveto resharpen or replace tool often. Then the production rate may not be increased finally and a poor m

27、achined surface is generated.3.2 Which tool materials would be suitable for interrupted cutting operations? Why? Answer: The tool materials having good toughness such as HSS, whisker-reinforced nanocrystalline tool materials, would be suitable for interrupted cutting operation. Because in interrupte

28、d cutting the tool will suffer impact coming from workpiece, if the tool has no enough impact toughness it will break, generally,chipping willoccur in its edges or nose.3.3 Describe the conditions under which broaching would be the preferred method of machining.Answer: The conditions which broaching

29、 would be the preferred consideration include: a large numbers of workpiece will be broached; there are high requirements on dimension accuracy and machined surface finish for the workpiece; the the workpiece has a suitable structure so that it can be clamped securely in broaching machine, and it sh

30、ould have sufficient strength and stiffness to withstand cutting forces during broaching.3.4 Why is the stiffness of machine tool important in machining operations?Answer: Because low stiffness of machine tool will result in larger magnitudes of vibration and chatter in cutting tools and machines, a

31、nd can have adverse effects on product quality. The possible troubles include poor machined surface finish, loss of dimension accuracy of the workpiece, premature wear, chipping and failure of the cutting tool, damage to the machine components and objectionable noise, etc.3.5 It is generally recomme

32、nded that, when grinding hardened steels, the grinding wheel should be of a relatively soft grade. Explain the reason.Answer: The grade of a grinding wheel is a measure of the bond s strength. A softer wheel has a weaker bond and /or a less amount of bonding material. It is recommended for harder wo

33、rkpiece such as hardened steel, because the dull grains are easily dislodged and other sharp grains can contact the workpiece to remove chips continually, so as to reduce residual stresses and thermal damage to the workpiece.4 Synthesis and design (Open Test. 30 marks, 15 marks for each)Observing Fi

34、g 3. The a) and b) show two cutting tools, and the c) and d) show two parts. Choose one from a), b) and one from c),d) to do your design.1) Which kind is the cutting tool? What operation can be done with the cuttingtool? According with the tool materials and geometries, analyzethe appliedperformance

35、 of the tool.2) The part c) is made from normal medium carbon steel, 5 pieces are required; the part d) is made from wrought aluminum, 10,000 are required. Please choose suitable process methods to machine the part, and arrange the process routing for it.8a) b)c)d)Fig. 31) a) It is a turning tool (l

36、eft offset tool). The tool shank is made from medium carbon steel and there is a rhombic carbide insert clamped on the shank by a clamp screw. The insert is indexable and has four cutting edges, when one of its edge becomes dull, another sharp edge can be indexed to use. The tool has a positive work

37、ing rake angle and clearance angle, and a sharp corner, it can be used for external cylindrical or taper surface turning or facing. The tool has a 90 cutting edge angle, so it can be used to turn 90 stage surface. The tool is suitable tocutting cast irons or steels at higher cutting speeds and large

38、r back engagements of the cutting edges, but had better to avoid cutting discontinuously; it is suitable for dry cutting or turning with cutting fluids, but should avoid cooling discontinuously. Because carbide insert is hard and brittle, special attention should be given to proper mounting and usin

39、g the tool in order to prevent from impact and vibrating as well heat stress.b) It is an end milling cutter and made from HSS. It has a solid structure and flat end, four helical cutting edges. It can be holden by a collet or special chuck, cut workpiece with its circumferential cutting edges. It ca

40、n be used to mill plane, side surface and curved surface as well slot, but is not suitable to feed in axial direction. It is suitable to cutting nonferrous alloys, also ferrous alloys such as cast irons and mild or medium carbon steels. Because its hot hardness is low relatively, it is suitable to c

41、ut at lower cutting speeds and needs cooling continuously. However, it possesses good impact toughness, so, it can be used to cut discontinuously.2) c) The part has a stepped cylindrical shape, so it can be produced by turning.Only 5 pieces are needed, we can choose an energy lathe to make it with P

42、-type carbide insert or a HSSsolid tool, and choose a rolled stock as the blank. Because the part has a severe shape and position tolerance, so the left end face and cylindrical surface should be completed in one setup of the part. The through hole has a higher finish requirement, after drilling a f

43、inish turning is needed. In addition, screw threading and chamfer are needed.Machining routing: Sawing the blank (longer than 5 times of the part)holdingthe blank with a three chuck in lathe, let the overhang be little longer than the final length of the part facing one end rough-turning external su

44、rfaces medium finish-turning the 50 external cylindrical surface to the dimension for threading M50finishturning the 44 segment to dimension accuracy and the stepface with a left offset toolcoringdrilling the through holeinternalturning the holechamferinggrooving in the 50 external surfacescrewthrea

45、ding parting turning around the workpiece and chamfering another end.d) The part is made from wrought aluminum alloy, a quantity of 10,000 pieces anda roughness of Ra 1.6 is required, so someeconomic processes such as extrusion should be used to produce the blank and a semi-finish-machining, finish-

46、machining process should be applied. The through hole should be per-formed in the blank, then, the final dimension including the keyway may be broached optimally. There is no finish requirement for its external cylindricalsurface and side surfaces,so thesesurfaces do not need to be machined. The thr

47、ee end faces marked Ra3.2 can be are produced with end milling cuter (the left end face and right cylindrical end face also can be produced with face milling). In order to obtain a high machining efficiency, a special fixture should be designed for fixing the workpiece on milling machine.Machiningro

48、uting:fixingthe workpieceon a vertical millingmachine, millingtheleft endfaceturning around theworkpiece,millingthe right planeandcylindrical end facemounting the workpiece on a broaching machine, broachingthe through hole and the keyway.5 Comprehension and discussion (10 marks)As you can appreciate

49、, the cost of machining centers is considerably higher than more traditional machine tools. In view of the fact that many operations performed by these centers can also be done on conventional machines, how would you go about justifying the high cost of these centers? Do you think under what conditi

50、on weshould purchase a precise and expensive machining center, and when we should use an economic machining center, even traditional machine tools only?Answer outline:Machinine efficiencyMachining accuracy and roughness AutomationMultiple functionsMachining time, labor, workshop areaMachining Test P

51、aper1.3 There is a poor design consideration it and give your correction (5 markings).for each of the following workpieces, mark(a) to be threaded(b) to be shaped(c) gear to be Manufacturing Engineering and Technology(2005-06-14)Name:Student No:Score:1. Drawing and marking (Close Test. 15 markings)1

52、.1 Fig 1a) shows a turning tool. Please mark its major cutting edge and minor cutting edge, rake face and major flank, cutting edge angle, rake angle and clearance angle. (3.5 markings)1.2 Give the process method name, mark the main motion and feed motion(s) for each illustration in Fig 2. (6.5 mark

53、ings)generated(d) to be drilled (e) cavity to be milled (by end milling cutter)2. Judging. Mark V for true and x for false. (Close Test. 30 markings, 2 markings for each)2.1 It is always advisable to increase cutting speed in order to increase production rate. ( x)2.2 Long, continuous chips are unde

54、sirable because they tend to become entangled and interfere with cutting operations. (V)2.3 Tool with high brittleness and hardness, or large positive rake angle is easyto chipping. ( V)2.4 Whenusing carbide inserts to hard turning, we should cool the cutting zone with cutting fluid discontinously.

55、(x)2.5 In surface grinding we should use oils as grinding fluids and in thread grinding we should use water-based emulsions. ( x )2.6 Coated tools have unique properties, such as lower friction and higher resistance to cracks and wear, they can be used at high cutting speeds, reducing required machining time and costs. ( V)2.7 Diamond tools are usually used to finish-machining cast iron and steels. (x )2.8 In machining, workpieces made from aluminum and magnesium alloys have less tendency to chatt