连杆把活塞所受的力传给曲轴并和曲轴一起把活塞的往复运动转变为曲轴的旋转运动，其每个循环中承受交替两次拉应力和压应力，受力频率很高。由于连杆承受很大的载荷，并在转动的疲劳载荷下工作，故连杆不仅对强度有较高的要求，而且对质量公差提出高的要求。
连杆形状复杂，模锻时，其工字形杆部易产生折叠，特别是工字形底部宽高比大于5的连杆更易产生折叠。解决措施主要是控制坯料体积和预、终锻工字形部位横截面积的比值，并挤压成形。另外连杆在切边时极易变形，可以在设计终锻模膛时，采用尺寸补偿来解决，但这要求锻造温度和生产节拍恒定，还必须保证切边刃口质量。最好采用切边和校正复合模。近年又出现胀断连杆新技术。
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.
