【正文】 at its cut surface can flow by with minimum rubbing against the tool. To save time, a portion of the end flank of the tool may sometimes be left unground, having been previously forged to size. In such case, this endclearance angle, numbered 4, measured to the end flank surface below the ground portion, would be larger than the relief angle. Often the end cutting edge is oblique to the flank. The relief angle is then best measured in a plane normal to the end cutting edge perpendicular to the base of the tool. This clearance permits the tool to advance more smoothly into the work. The siderelief angle, indicated as 5, is measured between the side flank, just below the cutting edge, and a line through the cutting edge perpendicular to the base of the tool. This clearance permits the tool to advance more smoothly into the work. Angle 6 is the endcuttingedge angle measured between the end cutting edge and a line perpendicular to the side of the tool shank. This angle prevents rubbing of the cut surface and permits longer tool life. The sidecuttingedge angle, numbered 7, is the angle between the side cutting edge and the side of the tool shank. The true length of cut is along this edge. Thus the angle determines the distribution of the cutting force. The greater the angle, the longer the tool life。這種車床可以控制工具的機械進給。同樣地，在操作中應(yīng)該小心，以避免損傷導(dǎo)軌。目前發(fā)展的趨勢是通過電氣的或機械的裝置進行無極變速。 主軸由電動機經(jīng) V 帶或無聲鏈裝置提供動力。通常在活動套筒的外表面刻有幾英寸長的刻度，以控制尾座的前后移動。 溜板箱裝在大拖板前面，通過溜板箱內(nèi)的機械裝置可以手動和動力驅(qū)動大拖板以及動力驅(qū)動橫拖板。光杠通過摩擦離合器驅(qū)動拖板移動，離合器可能會產(chǎn)生打滑現(xiàn)象。一些老式的或價廉的車床為了能夠得到所有的進給量和加工出多有螺紋，必須更換主軸 和變速箱之間的齒輪系中的一個或兩個齒輪。為了澄清已有的混亂的概念和術(shù)語，美國機械工程師 協(xié)會頒布了 ASA 標(biāo)準 B522— 1950，本文的術(shù)語即以此為依據(jù)。它確保工件和刀具之間有間隙使得切屑經(jīng)過刀具時摩擦最小。該角可減少刀具和已加工表面之間的摩擦，延長刀具的使用壽命。 刀具材料 已有許多刀具材料 能滿足高金屬切削率的要求。 C 時仍能保持硬度，但在更高溫度下會迅速軟化。這些刀具比普通碳化鎢硬質(zhì)合金刀具更耐磨，使用氮化鈦涂層界面摩擦力減小，導(dǎo)致切削 力和刀具溫度降低。因為現(xiàn)代機床的設(shè)計功率只能適合硬質(zhì)合金刀具，目前，陶瓷只限于告訴精加工，此時，機床功率足夠進行輕加工。 合成多晶金剛石目前已被用于機夾刀片上，因其成本太高，目前應(yīng)用很少，但有時用于加工有磨蝕作用的鋁、硅合金，熔融石英和增強塑料，隨意的晶體取向改善了它們的沖擊抗力，使它們適合斷續(xù)切削。 陶瓷的熱傳導(dǎo)性比硬質(zhì)合金差，因此，盡管前刀面上的摩擦力通常較低，但其前刀面的溫度比硬質(zhì)合金的要高得多。 使用氧化鋁涂層和多晶氮化硼的其他涂層尚處于實驗階段，但它們很可能在加工鑄鐵、淬硬鋼和高熔點合金時有重要應(yīng)用。 ：這是 20 世紀 20 年代晚期德國出現(xiàn)的硬質(zhì)合金刀具，通常是將碳化鎢或碳化鎢和碳化鈦或碳化鉭的混合物以粉末形式沉積在鈷或鎳的基體上。 ：才刀具歷史上，高碳鋼是最早用于工業(yè)上的刀具材料，但目前已幾乎全部被廢棄不用了，因為它在 220176。由于刀具切削長度是沿著此切削刃的，因此，側(cè)切削刃角決定了切削力的分布。在這種強況下，從斷后刀面刃磨部位下量出的角度（角度 4）比端后角大。圖 142 所示各個角度定義如下： 主視圖中的角度 1 為背前角，它是在垂直于刀具基面的縱向剖面內(nèi)的平行于刀柄的一條直線與刀面之間的夾角。本文向大家介紹刀具的幾何參數(shù)和刀具材料。通過溜板箱前面的夾緊手柄可以使對開螺母緊緊包合絲杠。手輪的另一端與溜板箱背面的小齒輪連接，小齒輪與齒條嚙合，齒條倒裝在床身前上邊緣的下面。 拖板組件用于安裝和移動切削工具。 尾座組件主要由三部分組成。主軸中有一個貫穿全長的通孔，長棒料可以通過該孔送料。大多數(shù)現(xiàn)代車床的導(dǎo)軌要進行變面淬火處理，以減少磨損和擦傷，具有更大的耐磨性。 圖 151 中標(biāo)出了車床的主要部件：床身、主軸箱組件、尾架組件、拖板組件、變速齒輪箱、絲杠和光杠。車削很少在其他種類的機床上進行，因為其他機床都不能像車床那樣方便地進行車削加工。 but the possibility of chatter increases. A promise must, as usual, be reached. The nose angle, number 8, is the angle between the two ponent cutting edges. If the corner is rounded off, the arc size is defined by the nose radius 9. the radius size influences finish and chatter. Cutting Tool Materials A large number of cutting tool materials have been developed to meet the demands of high metalremoval rates. The most important of these materials and their influence on cutter design, are described below. High Carbon Steel. Historically, high carbon steel was the earliest cutting material used industrially, but it has now been almost entirely superseded since it starts to temper at about 220℃ and this irreversible softening process continues as temperature increases. Cutting speeds with carbon steel tools are therefore limited to about (30ft/min) when cutting mild steel, and even at these speeds a copious supply of coolant is required. Highspeed Steel. To overe the low cutting speed restriction imposed by plain carbon steels, a range of alloy steels, known as highspeed steels, began to be introduced during the early years of this century. The chemical position of these steels varies greatly, but they basically contain about % carbon and 4% chromium, with addition of tungsten, vanadium, molybdenum and cobalt in varying percentages. They maintain their hardness at temperatures up to about 600℃ , but soften rapidly at cutting speeds in excess of (350ft/min), and many cannot successfully cut mild steel faster than (150ft/min). Sintered Carbides. Carbide cutting tools, which were developed in Germany in the late 1920s, usually consist of tungsten carbide or mixtures of tungsten carbide and titanium or tantalum carbide in powder form, sintered in a matrix of cobalt or nickel. Because of the paratively high cost of this tool material and its low rupture strengt