連桿把活塞所受的力傳給曲軸并和曲軸一起把活塞的往復(fù)運(yùn)動(dòng)轉(zhuǎn)變?yōu)榍S的旋轉(zhuǎn)運(yùn)動(dòng)，其每個(gè)循環(huán)中承受交替兩次拉應(yīng)力和壓應(yīng)力，受力頻率很高。由于連桿承受很大的載荷，并在轉(zhuǎn)動(dòng)的疲勞載荷下工作，故連桿不僅對(duì)強(qiáng)度有較高的要求，而且對(duì)質(zhì)量公差提出高的要求。

  連桿形狀復(fù)雜，模鍛時(shí)，其工字形桿部易產(chǎn)生折疊，特別是工字形底部寬高比大于5的連桿更易產(chǎn)生折疊。解決措施主要是控制坯料體積和預(yù)、終鍛工字形部位橫截面積的比值，并擠壓成形。另外連桿在切邊時(shí)極易變形，可以在設(shè)計(jì)終鍛模膛時(shí)，采用尺寸補(bǔ)償來解決，但這要求鍛造溫度和生產(chǎn)節(jié)拍恒定，還必須保證切邊刃口質(zhì)量。最好采用切邊和校正復(fù)合模。近年又出現(xiàn)脹斷連桿新技術(shù)。

 The connecting rod transmits the force on the piston to the crankshaft and together with the crankshaft transforms the reciprocating motion of the piston into the rotating motion of the crankshaft. In each cycle, the connecting rod bears two alternating tensile and compressive stresses, with a high frequency of stress. Because the connecting rod bears a large load and works under the rotating fatigue load, the connecting rod not only has a high demand for strength, but also for the quality tolerance.

    The shape of the connecting rod is complex. When forging, the I-shaped part of the connecting rod is easy to fold, especially when the width height ratio of the I-shaped bottom is greater than 5. The solution is mainly to control the ratio of the volume of the blank to the cross-sectional area of the I-shaped part of the pre and final forging, and to extrude. In addition, the connecting rod is easy to deform when cutting, which can be solved by dimension compensation when designing the final forging die bore, but this requires constant forging temperature and production beat, and must guarantee the quality of cutting edge. It is better to use trimming and correction compound die. In recent years, new technology of expanding and breaking connecting rod has appeared.