【正文】 ４２ 論文圖紙，請聯(lián)系 :68661508 附件 1 Fracture splitting technology of automobile engine connecting rod Abstract The fracture splitting method is an innovative processing technique in the field of the automobile engine connecting rod (con/rod) manufacturing. Compared with traditional method, the technique has remarkable advantages. It can decrease manufacturing procedures, reduce equipment and tools investment and save energy. Hence the total production cost is greatly reduced. Furthermore, the technique can also improve product quality and bearing capability. It provides a high quality, high accuracy and low cost route for producing connecting rods (con/rods). The method has attracted extensive attention and has been used in some types of con/rods manufacturing. The process and its key factors such as materials, notches for fracture splitting, fracture splitting conditions and fracture splitting equipment are discussed in detail. ４３ Keywords Automobile engine Connecting rod Fracture splitting New process 1 Introduction In recent years, with the rapid development of the automobile industry, the petition in the international automobile markets has bee more severe. New market conditions demand manufacturers employ higher quality, greater efficiency and lower cost manufacturing technology to fabricate automobile parts so as to improve their petitive capability and meet the market requirements. Therefore, many new technologies for producing parts have been developed. The con/rod is an important part of engine and its processing technology has been gaining great intention. The fracture splitting technology of con/rod is an innovative processing technique that appeared in the 1990s. Compared with the traditional method, the process owns the advantages of greatly improving product quality and production efficiency and dramatically reducing cost and energy [1–4]. Therefore, the technology has been studied and applied extensively. Some famous panies, such as GM Ford and Chrysler in the USA and Benz and BMW in Germany, etc., employ the technology to manufacture con/rods [5]. GM, Ford, MTS SYSTEM (America), ALFING and EXCELLO (German), etc., have successfully developed production equipment and production lines for fracture splitting con/rod [6, 7]. Now the technology is being mature. It has a very low defect ratio and has been used in the mass production of some types of con/rods. 2 Principle of con/rod fracture splitting technique The con/rod processing procedure is shown in Fig. 1. The traditional method is a machining technique in which the big end of a con/rod is cut off by a milling cutter and the con/rod is divided into two parts: a cap and a rod. In the technique, there exist two major requirements. (1) The cap and rod should have high precision rejoining surfaces, so many later machining procedures such as rough grinding and finish grinding, etc, are required. (2) The parts such as bolts used to position and the structures of whorl hole are very plex, and still the whorl hole is demanded to keep a high vertical level to surfaces. All these requirements greatly increase the processing difficulty, procedures and cost. However, the fracture splitting technique of con/rod, which is a mechanical method, settles the above questions perfectly. From Fig. 1, it can be seen that on the inner side of con/rod’s big end hole two symmetrical ４４ notches with the same shape and size are first broached, forming the starting point of splitting cracks out of stress concentration effect. Then, a push key with wedge shape is drawn to move downwards and push the fixture of the big end to move transversely, resulting in the big end brittle fracturing from two broached notches. At last these two split parts are assembled with bolts on a special equipment so as to perform later processes. The 3D structure characteristic of uneven cleavage surfaces can be seen in the process. It ensures a perfect fit between the cap and rod, which makes the two parts accurately positioned and assembled. Therefore, there is no need to machine joint surfaces of the cap and rod and use abrasive finishing processes to process the whorl hole and employ parts such as inserted pins, dowels or reamer bolts for positioning. The structures of traditional bolt and whorl hole are simplified and the whole machining process is also reduced. For example, as far as the processing of whorl hole is concerned, the traditional method needs 14 procedures, but it only requires six steps by applying fracture splitting method (Fig. 2). It is reported that the fracture splitting process can decrease manufacturing procedure