Optimization of forging process in medium frequency induction heating furnace for diesel engine connecting rod shaft

The diesel engine connecting rod is the core part of the diesel engine. Generally, a large diesel engine has multiple sets of connecting rods and covers, so the batch size is large. Usually the connecting rod is divided into two parts: connecting rod cover and connecting rod body. The manufacturing requirements are high. From raw materials to parts manufacturing, the following processes are required: blank forging - blank processing - heat treatment - finished product. The requirements for each process are very high. Among them, the blank section refers to a complete set of procedures for producing forgings from raw materials, and it is also the first process, which has a very important impact on the quality of the final product of the connecting rod. The forging process of connecting rod blanks using medium frequency induction heating furnace generally includes more than 10 processes, usually: raw material blanking - heating - blanking - grinding - die forging - heat treatment - shot blasting - flaw detection - grinding - inspection - send process.

In order to improve the blanking efficiency of the connecting rod body, an optimization of the blanking process of the connecting rod body is proposed based on the integration of various blanking processes of the connecting rod body and through production practice.

Firstly, three-dimensional modeling is carried out on the connecting rod shaft, and secondly, using the analysis function of the three-dimensional software, as many cross-sections as possible are made on the connecting rod body, and the area parameters of the cross-sections are analyzed. Transfer the analysis results to a spreadsheet file, add the flash allowance required for forging, which is the cross-sectional area of the forging blank. After analysis, you can analyze the change in the cross-sectional area of the entire forging and the change in the corresponding bar radius.

According to the bar radius diagram and the position and size of the section, by optimizing the sharp corners on the diagram, the rough shape of the blank and the relatively accurate size of the blank can be determined. After optimizing the sharp corners, the rough shape and comparison of the blank can be determined. Accurate blank size, which is basically consistent with the change in the cross-sectional area of the blank originally designed for the forging, and is close to the change in the cross-sectional area of the forging. In actual production, the general formula of the first blank’s blanking method is about 2h, and a better optimization is made according to the curve of the bar radius.

After production practice verification, this form of billet has the following advantages:

(1) The shape is simpler, and the working hours of the billet forging process are reduced by about half.

(2) This form of blanking can remove more surface oxide scale that affects the quality of forgings in the subsequent die forging process.

(3) This form of blanking can be produced on roll forging equipment and is suitable for production on connecting rod production lines.

(4) The material utilization rate of the optimized connecting rod body has increased from about 75% to over 85%. According to the mass production of connecting rods, more raw material costs can be saved.

(5) Using this solution can also save the cycle time of forging process development.