0053-工藝夾具-差速器殼工藝規(guī)程和鉆端面12個12.5mm孔鉆床夾具設(shè)計,工藝,夾具,差速器,規(guī)程,以及,端面,12,十二,mm,妹妹,鉆床,設(shè)計 摘 要 通過對“差速器殼”的結(jié)構(gòu)以及工藝性分析，介紹一種殼類零件的鉆削端面（法蘭盤）孔加工及夾具的設(shè)計，其結(jié)構(gòu)合理操作方便，大大提高了效率，使企業(yè)在大中批生產(chǎn)降低成本，提高產(chǎn)品的競爭力。 關(guān)鍵詞：工藝； 速器殼器； 夾具 Abstract By analysing the structure and craft of "differential device", and using the basic principle of group technology (CAPP) , to introduce the design of the drill and paring end surface hole (flange plate) processing and jig of a kind of shell accessory. With its reasonable structure and ease of operation, greatly enhanced the efficiency, that the enterprises reduce the cost in the mass production, and enhance the competition ability of the products. Key word: Craft differential device jig 附錄 Automobile differential device The motor car engine power after the coupling, the transmission gearbox, the drive shaft, the final biography delivers driving axle about to assign again for semi axis actuates the wheel, in this transmission of power way, driving axle is last always becomes, its major component is the reduction gear and the differential device. The reduction gear function is decelerates increases rectangular, this function depends entirely on between the gear and the gear meshes completes, compared with is easy to understand. But the differential device quite is difficult to understand that, what is called the differential device, why wants "the difference fast"? The automobile differential device is actuation host. Its function is while to two side semi axis transmissions powers, allows nearby two semi axis to revolve by the different rotational speed, satisfies two side wheels to the form which purely rolls not to make same lengge the travel as far as possible, reduces the tire and the ground friction.automobile when the corner the wheel trajectoryis a circular arc, if the automobile ten left is curved, the circular arc central point in left side, in the same time, the arc which right flank the wheel walks compared to a left side turn of Zichang, in order to balance this difference left side, wants wheel slow, right side wheel quick, makes up the distance with the different rotational speed the difference. If back wheel makes a whole, is unable to achieve two sides wheels the rotational speed difference, also is cannot achieve the automatic control. In order to solve this problem, as early as in 100 years ago, French Reynold car company's founder Louis Reynold designed the differential device this gadget ordinary differential device by the planet gear, planetary gear, components and so on rear axle shaft gear has been composed. The engine power classics and commentaries moving axis enters the differential device, the direct drive planetary gear frame, leads left, right two again by the planetary gear semi axis, separately actuates left, the right wheel. The differential device design request satisfies: (leftsemi axis rotational speed) (rightsemi axis rotational speed) =2 (planetary gear rotational speed). When automobile go alone, is left, the right wheel and a planetary gear three rotational speed equally is at the state of equilibrium, but when automobile curve three states of equilibrium are destroyed, cause an inside turn of rotational speed to reduce, a flank turn of rotational speed increases. This kind of adjustment is automatic, here involves "the smallest energy consumption principle", also is on the Earth all objects all favors to consumes energy the smallest condition. For example admits a grain of bean in a bowl, the bean can automatically pause in the bowl bottom but cannot pause in the bowl wall, because the bowl bottom is the energy lowest position (potential energy), its automatic selection static (kinetic energy is smallest) but cannot the unceasing movement. Similar truth, wheel when curve also can automatically tend to the energy consumption lowest condition about, when automatically adjusts a turn of rotational speed. works as the curve according to the radius of turn, because outside side wheel has the phenomenon which slippery tows, in side wheel has wheelspin the phenomenon, two driving gears this time can opposite have two directions to attach the thrust augmentation, because "the smallest energy consumption principle", inevitably causes two side wheels the rotational speeds to be different, thus destroyed three balances relations, and through semi axis reflected to the rear axle shaft gear on, forces the planet gear to have the rotation, makes the flank semi axis rotational speed to speed up, the inside semi axis rotational speed reduces speed, Thus realizes two sidecars turn of rotational speeds difference. On the automobile uses the gear drive the part to have driving axle, the transmission gearbox, the engine, the azimuth training gear and so on always becomes, the different part uses a form different size not gear. In all kinds of gear, some one name named "the hyperbolic curve" the gear, matches in the market in the steam also to have specially uses in its lubricating oil to be called "the hyperbolic curve gear oil". This kind of gear uses on the driving axle main gear box. On the passenger vehicle main gear box generally uses the hyperbolic curve gear. This is because the hyperbolic curve gear compares with the spiral bevel gear, former revolution noise few, work steadier, turns the tooth intensity to be higher, moreover also has the drive gear spool thread to be allowed the relative driven gear disalignment characteristic, this point regarding the，automobile technical performance count for much, engineer to be allowed in not to change the engine the position size to be allowed directly to change driving axle the ground clearance, also is changes the entire vehicle the ground clearance. Some automobiles produce the passenger vehicle and the movement leisure vehicle on the identical frame, its chassis parameter transformation also has used hyperbolic curve gear this characteristic. Because has these merits, at present automobile driving axle already tended to uses the hyperbolic curve gear, in fact recent years imported the automobile basically was uses the hyperbolic curve gear, the domestically produced automobile also has many vehicle types to use the hyperbolic curve gear, and already more and more many in center, on the heavy freight vehicle obtained uses.when the hyperbolic curve gear worked, between the tooth face can have in a big way relatively skids, also the tooth face pressure was very big, the tooth face lubricant film is easily destroyed. In order to reduce the friction, enhances the efficiency, must have to use includes guards against blows the wound chemical additive special-purpose hyperbolic curve gear oil, cannot use other gear oil to replace, otherwise will cause the tooth face rapid attrition and the abrasion, seriously will affect the automobile the running status. 汽車的差速器 汽車發(fā)動機的動力經(jīng)離合器、變速器、傳動軸，最后傳送到驅(qū)動橋再左右分配給半軸驅(qū)動車輪，在這條動力傳送途徑上，驅(qū)動橋是最后一個總成，它的主要部件是減速器和差速器。減速器的作用就是減速增矩，這個功能完全靠齒輪與齒輪之間的嚙合完成，比較容易理解。而差速器就比較難理解，什么叫差速器，為什么要“差速”？ 汽車差速器是驅(qū)動轎的主件。它的作用就是在向兩邊半軸傳遞動力的同時，允許兩邊半軸以不同的轉(zhuǎn)速旋轉(zhuǎn)，滿足兩邊車輪盡可能以純滾動的形式作不等距行駛，減少輪胎與地面的摩擦。 汽車在拐彎時車輪的軌線是圓弧，如果汽車向左轉(zhuǎn)彎，圓弧的中心點在左側(cè)，在相同的時間里，右側(cè)輪子走的弧線比左側(cè)輪子長，為了平衡這個差異，就要左邊輪子慢一點，右邊輪子快一點，用不同的轉(zhuǎn)速來彌補距離的差異。 如果后輪軸做成一個整體，就無法做到兩側(cè)輪子的轉(zhuǎn)速差異，也就是做不到自動調(diào)整。為了解決這個問題，早在一百年前，法國雷諾汽車公司的創(chuàng)始人路易斯.雷諾就設(shè)計出了差速器這個玩意。 普通差速器由行星齒輪、行星輪架（差速器殼）、半軸齒輪等零件組成。發(fā)動機的動力經(jīng)傳動軸進入差速器，直接驅(qū)動行星輪架，再由行星輪帶動左、右兩條半軸，分別驅(qū)動左、右車輪。差速器的設(shè)計要求滿足：（左半軸轉(zhuǎn)速）+（右半軸轉(zhuǎn)速）=2（行星輪架轉(zhuǎn)速）。當汽車直行時，左、右車輪與行星輪架三者的轉(zhuǎn)速相等處于平衡狀態(tài)，而在汽車轉(zhuǎn)彎時三者平衡狀態(tài)被破壞，導致內(nèi)側(cè)輪轉(zhuǎn)速減小，外側(cè)輪轉(zhuǎn)速增加。 這種調(diào)整是自動的，這里涉及到“最小能耗原理”，也就是地球上所有物體都傾向于耗能最小的狀態(tài)。例如把一粒豆子放進一個碗內(nèi)，豆子會自動停留在碗底而絕不會停留在碗壁，因為碗底是能量最低的位置（位能），它自動選擇靜止（動能最小）而不會不斷運動。同樣的道理，車輪在轉(zhuǎn)彎時也會自動趨向能耗最低的狀態(tài)，自動地按照轉(zhuǎn)彎半徑調(diào)整左右輪的轉(zhuǎn)速。 當轉(zhuǎn)彎時，由于外側(cè)輪有滑拖的現(xiàn)象，內(nèi)側(cè)輪有滑轉(zhuǎn)的現(xiàn)象，兩個驅(qū)動輪此時就會產(chǎn)生兩個方向相反的附加力，由于“最小能耗原理”，必然導致兩邊車輪的轉(zhuǎn)速不同，從而破壞了三者的平衡關(guān)系，并通過半軸反映到半軸齒輪上，迫使行星齒輪產(chǎn)生自轉(zhuǎn)，使外側(cè)半軸轉(zhuǎn)速加快，內(nèi)側(cè)半軸轉(zhuǎn)速減慢，從而實現(xiàn)兩邊車輪轉(zhuǎn)速的差異。汽車上用到齒輪傳動的部件有驅(qū)動橋、變速器、發(fā)動機、方向機等總成，不同的部件采用形式不同大小不一的齒輪。在各式各樣的齒輪中，有一種名叫“雙曲線”的齒輪，在汽配市場上還有專門用于它的潤滑油叫做“雙曲線齒輪油”。這種齒輪用在驅(qū)動橋的主減速器上。 轎車上的主減速器一般采用雙曲線齒輪。這是因為雙曲線齒輪與螺旋錐齒輪比較，前者運轉(zhuǎn)噪音少，工作更平穩(wěn)，輪齒強度較高，而且還具有主動齒輪軸線可以相對從動齒輪軸線偏移的特點，這一點對于汽車的技術(shù)性能非常重要，工程師可以在不改變發(fā)動機的位置尺寸就可以直接改變驅(qū)動橋的離地間隙，也就是改變整部車的離地間隙。 有些汽車在同一車架上生產(chǎn)轎車和運動休閑車，其底盤的參數(shù)變換也是利用了雙曲線齒輪這一特性。由于有這些優(yōu)點，目前汽車的驅(qū)動橋已經(jīng)趨向于用雙曲線齒輪，實際上近年進口汽車基本上是采用雙曲線齒輪，國產(chǎn)汽車也有許多車型采用雙曲線齒輪，并已經(jīng)越來越多地在中、重型貨車上得到采用。 但雙曲線齒輪工作時，齒面間會有較大的相對滑動，且齒面壓力很大，齒面油膜容易被破壞。為減少摩擦，提高效率，必須要采用含有防刮傷添加劑的專用雙曲線齒輪油，絕不能用其它的齒輪油代替，否則將使齒面迅速磨損和擦傷，嚴重影響汽車的運行狀態(tài)。 45 Forging craft not when produces flaw 1. Big crystal grain hyperpyrexia and the distortion degree insufficiency, or the end hammers the hyperpyrexia, or the distortion degree falls the human critical deformation range to cause. Aluminum alloy distortion degree oversized, forms the texture; Also the heat-resisting alloy distortion temperature excessively is low, forms when the mix distortion organization possibly causes the thick crystal grain 2. The crystal grain is non-uniform The crystal grain non-uniform is refers to forging certain spots the crystal grain to be specially thick, certain spots are actually small. Has the crystal grain non-uniform primary cause is semifinished materials each place distortion causes the crystal grain stave degree non-uniform not one, either the partial region distortion degree falls the human critical deformation range, either heat-resisting alloy partial work hardening, either when quenching heating the partial crystal grain is thick. High-temperature steel and heat-resisting alloy to crystal grain non-uniform specially sensitive. The crystal grain non-uniform will cause the forging the lasting performance, the weary performance to drop obviously. 3.Chilling phenomenon When distortion because the temperature somewhat low or the distortion speed too is quick, as well as hammers the after-cooling excessively quickly, possibly causes the conditioning which the recrystallization causes not to be able to follow the strengthening which the distortion causes (hardening), after thus caused the hot forging the forging interior still the part retention cold-work organization. This kind of organization's existence enhanced the forging intensity and degree of hardness, but reduced the plasticity and toughness. The serious chilling phenomenon possibly causes the forging crack, sees example 78, 79, 83, 84. 4.Crack The crack is usually when forging has the big tensile stress, the shear stress or the additional tensile stress causes. The crack occurs the spot usually is biggest in the semifinished materials stress, the thickness thinnest spot. If the semifinished materials surface and the interior have the micro crack, or in the semifinished materials have the organization flaw, either hot-working temperature not when causes the material plasticity to reduce, either distortion speed excessively quickly, distortion degree oversized, surpasses the material permission the plastic indicator and so on, then in removes thick, pulls out long, the punch holes, the broaching, curving and working procedures and so on in extrusion all possibly produces the crack. 5.Chap The chap is presents the shallow turtle shape crack in the forging surface. In the forging forming the tension stress surface (e.g., fill has not protruded part or curving part) easiest to produce this kind of flaw. Causes the chap internal cause possibly is various:①Raw material gathers fusible elements and so on the Cu, Sn excessively are many.②When high temperature long time heating, the steel materials surface has the copper to separate out the surface which, the superficial crystal grain thick, the decarbonization, or passes through heats up many times.③The fuel measures including the sulfur excessively high, has the sulfur to infiltrate the human steel materials surface. 6.Edge crack The edge crack is when the drop forging and the cutting edge produces the crack in a minute modular surface place. The edge crack produces the reason possibly is:①In drop forging operation because hits hard causes the metal intense flowing to produce puts on the muscle phenomenon.②The magnesium alloy die forged item cutting edge temperature excessively is low; Copper alloy die forged item cutting edge hyperpyrexia. 7.Minute modular surface crack The minute modular surface crack refers to the crack which produces along a forging minute modular surface. Raw material mixes with nonmetallic many, when drop forging to divides the modular surface flowing and the centralism or the pipe remaining after the drop forging pushes the human edge often the shape ingredient modular surface crack. 8.Fold The fold was in the flow of metal process has oxidized the surface layer metal converged to form together. It may be (or multi-stocks) the metal convection convergence forms by two; Also might be the massive flowing is close to the part rapidly by a metal the surface layer strap flowing, both convergence will form; Also may be because the distortion metal has, the backflow curving forms; Also may be the partial metal local distortion, is oppressed others in another part of metals to form. Folding and raw material and semifinished materials shape, mold design, formed working procedure arrangement, lubrication situation and forging actual operation and so on related Not only the fold reduced the components load bearing area, when works because here stress concentration often becomes the weary source 9.Puts on the class Puts on the class is the streamline distributes the improper one form. Is putting on flows the area, has certain angle distribution the streamline to converge originally to form together puts on the class, possibly and causes to put on flows the area inside and outside grain size difference to be disparate. Puts on the reason which the class produces with the fold to be similar, is by two metals or strap, but puts on flows the part which another metal affluxes form the metal still was a whole puts on the class to cause the forging mechanics performance to reduce, when puts on especially flows the belt both sides crystal grain difference is disparate, the performance reduces obviously. 10.The forging streamline distribution is not suitable The forging streamline distribution along is not refers on forging low time has streamline disorder phenomena and so on streamline cut-off, backflow, turbulent flow. If the mold design does not work as or the forging method choice is unreasonable, prefabricated semifinished materials streamline disorder; The worker does not operate when and the mold wears causes the metal to produce the non-uniform flowing, all may cause the forging streamline distribution not to be suitable. The streamline along cannot cause each mechanics performance to reduce, therefore regarding the important forging, all has the request which the streamline distributes. 11.The casting organization remains The casting organization remains mainly appears in uses the ingot casting to make the semifinished materials in the forging. The cast condition organization mainly remains in the forging difficult deformation range. Forging compared to insufficient and forging method not when is the primary cause casting organization which the casting organization remains produces remains can cause the forging the performance drop, attacks the tenacity and the weary performance in particular and so on. 12.Carbide segregation rank not symbol request The carbide segregation rank symbol request mainly does not appear in the Lai body labor molding tool steel. Mainly is in the forging carbide distributes non-uniform, assumes the greatly massive centralism distribution or assumes the netted distribution. Creates this kind of flaw the primary cause is raw material carbide segregation rank is bad, adds it changes hammers when hammers compared to insufficient or the forging method not when has this kind of flaw forging, when heat treatment quenching easy partial superheat and quenches the crack. Makes the cutting tool and the mold use when easy breaking and so on. 13.Banded structure The banded structure is the ferrite and the pearlyte, the ferrite and the austenite, the ferrite and the bainite as well as the ferrite and the martensite assumes the belt-shaped distribution in the forging one kind of organization, they appear in Asia altogether fold in the steel, the austenite steel and half martensite steel. This kind of organization, is when which the banded structure which two coexists in the situation forges distortion produces to be able to reduce the material the crosswise plastic indicator, specially resilience. Often is easy in forging either the components work along the lines of ferrite or two intersection point dehiscence. 14.Partial backfill insufficiency The partial backfill insufficient mainly occurs in the muscle rib, the convex angle, the corner, the fillet spot, the size does not conform to the pattern requirement. Produces the reason possibly is:①The forging temperature is low, the metal fluidity is bad;②The equipment tonnage insufficient or the hammer strength is insufficient;③The system molds the design not to be unreasonable, the semifinished materials volume or the section size are unqualified;④In the mold chest cavity piles up the oxide skin or the welded together distortion metal. 15.Owes the pressure Owes the pressure to refer is vertical increases, the reason to the minute modular surface direction size which produces possibly is generally:①The forging temperature is low.②The equipment tonnage is insufficient, hammer strength insufficiency or hammer number of times insufficient 16.Wrong moves Wrong moves is the forging is opposite along the minute modular surface upper half in the lower part has the displacement. Produces the reason possibly is:①Slide (hammer head) and between guide rail gap oversized;②The forging die design is unreasonable, lacks eliminates wrong moves the strength to close up an opening or the guide pillar;③Mold installment not good 17.The spool thread is curving The forging spool thread is curving, has the error with the plane geometry position. Produces the reason possibly is:①The forging leaves when the mold does not pay attention;②When cutting edge the stress is uneven;③The forging cools when various part of temperature decrease speed not one;④The cleaning up and the heat treatment improper 鍛造工藝不當產(chǎn)生的缺陷 1.大晶粒 大晶粒通常是由于始鍛溫度過高和變形程度不足、或終鍛溫度過高、或變形程度落人臨界變形區(qū)引起的。鋁合金變形程度過大，形成織構(gòu)；高溫合金變形溫度過低，形成混合變形組織時也可能引起粗大晶粒 2.晶粒不均勻 晶粒不均勻是指鍛件某些部位的晶粒特別粗大，某些部位卻較小。產(chǎn)生晶粒不均勻的主要原因是坯料各處的變形不均勻使晶粒破碎程度不一，或局部區(qū)域的變形程度落人臨界變形區(qū)，或高溫合金局部加工硬化，或淬火加熱時局部晶粒粗大。耐熱鋼及高溫合金對晶粒不均勻特別敏感。晶粒不均勻?qū)⑹瑰懠某志眯阅?、疲勞性能明顯下降。 3.冷硬現(xiàn)象 變形時由于溫度偏低或變形速度太快，以及鍛后冷卻過快，均可能使再結(jié)晶引起的軟化跟不上變形引起的強化（硬化），從而使熱鍛后鍛件內(nèi)部仍部分保留冷變形組織。這種組織的存在提高了鍛件的強度和硬度，但降低了塑性和韌性。嚴重的冷硬現(xiàn)象可能引起鍛裂，見實例78、79、83、84。 4.裂紋 裂紋通常是鍛造時存在較大的拉應(yīng)力、切應(yīng)力或附加拉應(yīng)力引起的。裂紋發(fā)生的部位通常是在坯料應(yīng)力最大、厚度最薄的部位。如果坯料表面和內(nèi)部有微裂紋、或坯料內(nèi)存在組織缺陷，或熱加工溫度不當使材料塑性降低，或變形速度過快、變形程度過大，超過材料允許的塑性指針等，則在撤粗、拔長、沖孔、擴孔、彎曲和擠壓等工序中都可能產(chǎn)生裂紋。 5.龜裂 龜裂是在鍛件表面呈現(xiàn)較淺的龜狀裂紋。在鍛件成形中受拉應(yīng)力的表面（例如，未充滿的凸出部分或受彎曲的部分）最容易產(chǎn)生這種缺陷。引起龜裂的內(nèi)因可能是多方面的：①原材料合Cu、Sn等易熔元素過多。②高溫長時間加熱時，鋼料表面有銅析出、表面晶粒粗大、脫碳、或經(jīng)過多次加熱的表面。③燃料含硫量過高，有硫滲人鋼料表面。 6.飛邊裂紋 飛邊裂紋是模鍛及切邊時在分模面處產(chǎn)生的裂紋。飛邊裂紋產(chǎn)生的原因可能是：①在模鍛操作中由于重擊使金屬強烈流動產(chǎn)生穿筋現(xiàn)象。②鎂合金模鍛件切邊溫度過低；銅合金模鍛件切邊溫度過高。 7.分模面裂紋 分模面裂紋是指沿鍛件分模面產(chǎn)生的裂紋。原材料非金屬夾雜多，模鍛時向分模面流動與集中或縮管殘余在模鍛時擠人飛邊后常形成分模面裂紋。 8.折疊 折疊是金屬變形過程中已氧化過的表層金屬匯合到一起而形成的。它可以是由兩股（或多股）金屬對流匯合而形成；也可以是由一股金屬的急速大量流動將鄰近部分的表層金屬帶著流動，兩者匯合而形成的；也可以是由于變形金屬發(fā)生彎曲、回流而形成；還可以是部分金屬局部變形，被壓人另一部分金屬內(nèi)而形成。折疊與原材料和坯料的形狀、模具的設(shè)計、成形工序的安排、潤滑情況及鍛造的實際操作等有關(guān) 折疊不僅減少了零件的承載面積，而且工作時由于此處的應(yīng)力集中往往成為疲勞源 9.穿流 穿流是流線分布不當?shù)囊环N形式。在穿流區(qū)，原先成一定角度分布的流線匯合在一起形成穿流，并可能使穿流區(qū)內(nèi)、外的晶粒大小相差較為懸殊。穿流產(chǎn)生的原因與折疊相似，是由兩股金屬或一股金屬帶著另一股金屬匯流而形成的，但穿流部分的金屬仍是一整體穿流使鍛件的力學性能降低，尤其當穿流帶兩側(cè)晶粒相差較懸殊時，性能降低較明顯。 10.鍛件流線分布不順 鍛件流線分布不順是指在鍛件低倍上發(fā)生流線切斷、回流、渦流等流線紊亂現(xiàn)象。如果模具設(shè)計不當或鍛造方法選擇不合理，預(yù)制毛坯流線紊亂；工人操作不當及模具磨損而使金屬產(chǎn)生不均勻流動，都可以使鍛件流線分布不順。流線不順會使各種力學性能降低，因此對于重要鍛件，都有流線分布的要求。 11.鑄造組織殘留 鑄造組織殘留主要出現(xiàn)在用鑄錠作坯料的鍛件中。鑄態(tài)組織主要殘留在鍛件的困難變形區(qū)。鍛造比不夠和鍛造方法不當是鑄造組織殘留產(chǎn)生的主要原因 鑄造組織殘留會使鍛件的性能下降，尤其是沖擊韌度和疲勞性能等。 12.碳化物偏析級別不符要求 碳化物偏析級別不符要求主要出現(xiàn)于萊氏體工模具鋼中。主要是鍛件中的碳化物分布不均勻，呈大塊狀集中分布或呈網(wǎng)狀分布。造成這種缺陷的主要原因是原材料碳化物偏析級別差，加之改鍛時鍛比不夠或鍛造方法不當具有這種缺陷的鍛件，熱處理淬火時容易局部過熱和淬裂。制成的刃具和模具使用時易崩刃等。 13.帶狀組織 帶狀組織是鐵素體和珠光體、鐵素體和奧氏體、鐵素體和貝氏體以及鐵素體和馬氏體在鍛件中呈帶狀分布的一種組織，它們多出現(xiàn)在亞共折鋼、奧氏體鋼和半馬氏體鋼中。這種組織，是在兩相共存的情況下鍛造變形時產(chǎn)生的帶狀組織能降低材料的橫向塑性指針，特別是沖擊韌性。在鍛造或零件工作時常易沿鐵素體帶或兩相的交界處開裂。 14.局部充填不足 局部充填不足主要發(fā)生在筋肋、凸角、轉(zhuǎn)角、圓角部位，尺寸不符合圖樣要求。產(chǎn)生的原因可能是：①鍛造溫度低，金屬流動性差；②設(shè)備噸位不夠或錘擊力不足；③制坯模設(shè)計不合理，坯料體積或截面尺寸不合格；④模膛中堆積氧化皮或焊合變形金屬。 15.欠壓 欠壓指垂直于分模面方向的尺寸普遍增大，產(chǎn)生的原因可能是：①鍛造溫度低。②設(shè)備噸位不足，錘擊力不足或錘擊次數(shù)不足 16.錯移 錯移是鍛件沿分模面的上半部相對于下半部產(chǎn)生位移。產(chǎn)生的原因可能是：①滑塊（錘頭）與導軌之間的間隙過大；②鍛模設(shè)計不合理，缺少消除錯移力的鎖口或?qū)е?；③模具安裝不良 17.軸線彎曲 鍛件軸線彎曲，與平面的幾何位置有誤差。產(chǎn)生的原因可能是：①鍛件出模時不注意；②切邊時受力不均；③鍛件冷卻時各部分降溫速度不一；④清理與熱處理不當