【正文】 。 3．當高速切削時，宜選用（高速鋼，硬質合金）刀具；粗車鋼時，應選用（YTYGYT30）。5．不經修配與調整即能達到裝配精度的方法稱為（互換法、選配法）。7．在四種車刀中，轉位車刀的切削性能（最好，最差）；粗磨時應選擇（硬，軟）砂輪。9．滾齒時，刀具與工件之間的相對運動稱（成形運動、輔助運動）。10．衡量已加工表面質量的指標有 。12．測量誤差是屬于（系統(tǒng)、隨機）誤差，對誤差影響最大的方向稱 方向。 14．輔助支承可以消除（0、2）個自由度，限制同一自由度的定位稱（完全定位、過定位）。二、 端面車刀的切削部分的結構由哪些部分組成？繪圖表示表示端面車刀的六個基本角度。（8分）五、 加工下述零件，要求保證孔的尺寸B＝30＋，試畫出尺寸鏈，并求工序尺寸L。如何加以改進。（8分）八、制訂下述零件的機械加工工藝過程，具體條件：45鋼，圓料ф70，單件生產。（10分）試題2參考答案一．1．一個工人在一臺機床上對一個（或多個）零件所連續(xù)完成的那部分工藝過程。端面車刀的六個基本角度：ro、αo、kr、kr’、λs、αo’三．被切金屬在刀刃的擠壓作用下，產生剪切滑移變形，并轉變?yōu)榍行嫉倪^程。四．u1 ＝ 18/4515/48, u2 ＝28/3515/48 u3 = 18/4535/28u4 ＝ 28/3535/28五．L ＝ 六．％，改進措施：將算術平均值移至公差帶中心，即使砂輪向前移動Δ，Δ＝。工序2：銑鍵槽（銑床）工序3：鉆4－Φ6孔（鉆床）工序4：去毛刺（鉗工臺）九．用V型塊及支承釘定位，符合要求，定位方案可行。2．當工件材料硬度提高時，切削力（增加，減少）；當切削速度提高時，切削變形（增加、減少）。4．為改善切削加工性，對高碳鋼采?。ù慊穑嘶穑┨幚?；對不銹鋼（淬火，調質）處理。6．精基準的選擇原則是 。8．機床的運動按其功用可分為 與 兩大類。滾齒時，刀具與工件之間的相對運動稱（成形運動、輔助運動）。11．夾緊力作用點應（靠近，遠離）工件的加工表面；工件以平面定位時，可以不考慮（基準不重合、基準位置）誤差。13．工藝系統(tǒng)剛度等于（Fy/y，Fz/y），工藝系統(tǒng)剛度大，誤差復映（大，?。?。15．生產類型通常分為 、 、 三種。（8分）三、量度切削變形的方法有幾種？各有什么特點？能否全面衡量金屬切削過程的物理本質？（8分）四、 列出切削公制螺紋的運動方程式，并寫出CA6140車床進給箱中基本變速組的八種傳動比。（8分）A六、 加工下述零件，以B面定位，加工表面A，保證尺寸10＋，試畫出尺寸鏈并求出工序尺寸L及公差。（8分）八、 根據所學知識，列出提高零件加工質量的措施。2． 制訂該零件的加工工藝過程。切斷車刀的六個基本角度：ro、αo、kr、kr’、λs、αo’三．量度方法有兩種：（簡單，直觀但結果近似，從塑性壓縮方面分析）。兩種方法都有片面性，不能全面反映金屬切削過程的物理本質。提高表面質量措施：采用合理的切削用量與刀具參數，采用冷壓強化與光整工藝，采用良好的切削液，減少積屑瘤、鱗刺和震動。 in a shaper, the tool travels along a straight path, and the workpiece is stationary. (√) Threejaw chucks have jaws that can be moved and adjusted independently of each other。 there are high requirements on dimension accuracy and machined surface finish for the workpiece。 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. a) b) c) d)Fig. 31) a) It is a turning tool (left 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 bees dull, another sharp edge can be indexed to use. The tool has a positive working 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 90176。stage surface. The tool is suitable to cutting cast irons or steels at higher cutting speeds and larger back engagements of the cutting edges, but had better to avoid cutting discontinuously。 in a shaper, the tool travels along a straight path, and the workpiece is stationary. (√) Collet is a longitudinallyspit tapered bushing, it usually used for holding round tools or workpieces having a small diameter. (√) If an existing hole has centerline deflection, we can correct it by reaming, while boring can only make an existing hole dimensionally more accurate. () In conventional milling (up milling), the feed direction is same as the cutting direction. () End milling is a versatile process, the production of cavities in forging or casting dies is usually done using ballnose end milling at high speed. (√) Hobbing is one of gear generating methods, which produces a variety of gears rapidly and with good dimensional accuracy. (√) A hard grinding wheel means its abrasive particles have very high hardness. ()3. Qualitative problems (Open Test. 20 markings, 4 markings for each) List the factors that contribute to poor surface finish in cutting.Answer: a) geometric factors such as a large feed and back engagement of tool edge, too small radius of tool nose or too large cutting edge angle, dull tool edge or tool chipping, builtup edge。 c) vibration and chatter in cutting. Which tool materials would be suitable for interrupted cutting operations? Why?Answer: The tool materials having good toughness such as HSS, whiskerreinforced nanocrystalline tool materials, would be suitable for interrupted cutting operation. Because in interrupted cutting the tool will suffer impact ing from workpiece, if the tool has no enough impact toughness it will break, generally, chipping will occur in its edges or nose. Describe the conditions under which broaching would be the preferred method of machining.Answer: The conditions which broaching would be the preferred consideration include: a large numbers of workpiece will be broached。 the the workpiece has a suitable structure so that it can be clamped securely in broaching machine, and it should have sufficient strength and stiffness to withstand cutting forces during broaching. We know that we may be able to decrease machining costs by increasing cutting speed. Explain which costs are likely to change, and how, as the cutting speed increases.Answer: Machining cost may be decreased by increasing cutting speed, because the machining time for per piece decreases due to the high production rate. However, also other variables may change with cutting speed. As cutting speed increases, the tool life generally decreases, then the tool cost will increase, as does the toolchanging cost. So, machining cost does not always decrease as the cutting speed increases. It is generally remended 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