坯料橫截面尺寸大，制坯形狀不合理，局部壓入式成形，模具模膛過(guò)渡處圓角半徑較小，操作時(shí)一次壓下量太大。  
　
　　消除折迭的方法  
　
　　將模具模膛的模鍛斜度由5°增大到7°；將模膛φ23mm與鍛件過(guò)渡處的圓角半徑由R3mm增大到R8mm；將鍛件易折迭部分模膛處的制造拋光方向順著金屬流動(dòng)方向進(jìn)行；將模膛表面粗糙度值Ra=1.6μm減小到Ra=0.4μm；將坯料制坯尺寸變?yōu)?8mm×58mm×74mm，在鍛件終鍛成形時(shí)按先輕后重的方式進(jìn)行操作，并適當(dāng)?shù)貪?rùn)滑上模模膛。  
　
　　軸承蓋裂紋的分析  
　
　　492Q汽油機(jī)軸承蓋鍛件，材料為L(zhǎng)Y11的擠壓棒料，下料尺寸為φ70mm×120mm，重1.3kg。當(dāng)沿坯料軸向鐓粗制坯后再終鍛，在鍛件坯料軸線45°方向產(chǎn)生宏觀斜裂，裂紋開(kāi)口角度為30°～50°。  
　
　　裂紋產(chǎn)生的原因  
　
　　擠壓鋁棒料具有明顯的各向異性，其中縱向機(jī)械性能明顯高于橫向機(jī)械性能(縱向韌性最大，而橫向韌性最小)。在終鍛開(kāi)始時(shí)在三向應(yīng)力不等的情況下或非三向壓應(yīng)力的作用下，存在最大剪應(yīng)力，易造成坯料晶粒間聯(lián)系破壞，不利于滑移變形的發(fā)展，變形能力差而產(chǎn)生斜裂。同時(shí)因變形不均而引起的附加應(yīng)力和溫度不均產(chǎn)生的熱應(yīng)力較大，變形大的部分和變形小的部分相互作用，拉應(yīng)力超出該部分強(qiáng)度時(shí)便產(chǎn)生開(kāi)裂。  
　
　　消除裂紋的方法  
　
　　嚴(yán)格控制始、終鍛溫度，減少坯料裝爐數(shù)量，縮短坯料出爐到鍛造的時(shí)間，當(dāng)坯料在加熱一定的時(shí)間后進(jìn)行翻動(dòng)；利用擠壓坯料沿軸向韌性好、塑性好的特點(diǎn)，沿坯料徑向即垂直于纖維方向鍛造壓扁制坯，然后終鍛。  
　
　　油堵折迭與裂紋的分析  
　
　　油堵鍛件，材料為L(zhǎng)Y11或LY12的擠壓棒料，下料尺寸為φ35mm×45mm，重0.08kg。在RFX-45箱式電爐中加熱，每次出爐量15件，但在鍛造10件以后，采用軸向或徑向鐓粗制坯，然后終鍛時(shí)，出現(xiàn)與沿分模面方向的飛邊成15°～35°的裂紋，并沿伸到鍛件。當(dāng)采用φ30mm×60mm的坯料沿軸向鐓粗制坯時(shí)，在鍛件環(huán)R10mm處四周產(chǎn)生較大的折迭。  
　
　　折迭與裂紋產(chǎn)生的原因  
　
　　每次坯料出爐量過(guò)多，始鍛溫度低，制坯終鍛時(shí)變形程度過(guò)大或鍛造比過(guò)大，鍛模預(yù)熱或潤(rùn)滑不當(dāng)。  
　
　　消除折迭與裂紋的方法  
　
　　選擇坯料規(guī)格的最小直徑為φ35mm，坯料加熱到480℃保溫2h，每次坯料出爐量在10件以下，終鍛按先輕后重的方式進(jìn)行，提高鍛模的預(yù)熱溫度，并每隔2件潤(rùn)滑上模一次。
　
　
　　The cross-sectional size of the blank is large, the shape of the billet is unreasonable, the local press-fit is formed, and the radius of the fillet is smaller.
　
　　Eliminate the folding method
　
　　The die forging angle of the mold cavity is increased from 5 ° to 7 °; the radius of the fillet φ23mm and the transition angle of the forging is increased from R3mm to R8mm; the polishing direction of the part is easy to be folded According to the direction of metal flow; the mold surface roughness value Ra = 1.6μm reduced to Ra = 0.4μm; the blank blank size into 38mm × 58mm × 74mm, forging the final forging when the first light weight To operate and to properly lubricate the upper mold cavity.
　
　　Analysis of Cracks in Bearing
　
　　492Q gasoline engine bearing cover forging material LY11 extrusion bar material, cutting the size of φ70mm × 120mm, weight 1.3kg. When the blanks are upsetted along the billet and then forged, the macroscopical fissures are generated in the direction of the 45 ° of the forging billet, and the opening angle is 30 ° ~ 50 °.
　
　　The cause of the crack
　
　　Extruded aluminum bar has obvious anisotropy, in which the longitudinal mechanical properties are significantly higher than the transverse mechanical properties (longitudinal toughness is the largest, and transverse toughness is the smallest). In the case of the final forging in the case of three-dimensional stress or non-three-way compressive stress under the action of the existence of the maximum shear stress, easy to cause the relationship between the billet crystal damage is not conducive to the development of slippage deformation, Produce an oblique crack. At the same time due to uneven deformation caused by the additional stress and temperature unevenness of the thermal stress generated by large deformation of the large part of the small part of the interaction, tensile stress exceeds the strength of the part of the crack.
　
　　Eliminate the crack method
　
　　Strict control of the beginning and end forging temperature, reduce the number of billet furnace, shorten the billet baked to forging time, when the blank after a certain period of time to turn the blank; the use of extruded billet along the axial toughness, good plasticity, Radial, that is, perpendicular to the direction of the fiber forging flattened blanks, and then the final forging.
　
　　Analysis of Oil Closure and Crack
　
　　Oil forging forgings, materials for the LY11 or LY12 squeeze bar, cutting the size of φ35mm × 45mm, weight 0.08kg. Heating in the RFX-45 box electric furnace, the amount of each time the amount of 15, but after 10 forging, the use of axial or radial upsetting blank, and then the final forging, and along the direction of the sub-surface with the flash Into a crack of 15 ° to 35 ° and extend to the forging. When the use of φ30mm × 60mm blank along the axial upsetting the blank, in the forging ring around the R10mm to produce a large fold.
　
　　The reason of folding and cracking
　
　　Each time the billet is too large, the initial forging temperature is low, the deformation degree of the blank forging is too large or the forging ratio is too large, the forging die is preheated or lubricated improperly.
　
　　Eliminate the method of folding and cracking
　
　　Select the blank size of the minimum diameter of φ35mm, blank heating to 480 ℃ insulation 2h, each billet out of the amount of 10 or less, the final forging the first light and heavy way to improve the forging die preheating temperature, and every 2 Lubrication on the mold once.