1. In the case of uneven mold, the data of important parts such as the length of the bearing seat and the height of the tie rod are very different from the standard values. When the connecting rod is straight, the force is uneven, which promotes the linear smooth rod. fracture.

2. When the mold is opened, the impact force at the moment when the machine is turned on is too large, causing the linear smooth rod to break.

3. A thermal stress is generated during the rapid heating of the mold, which causes the linear smooth rod to break.