Structural Parameter Design Of Conrod Fracture Splitting Clamp

Fracture splitting technology for engine connecting rod is a new manufacturingtechnology, the principle of which is to predefine crack groove at the center of thecrack end bore to generate stress concentration and then to make the fracture splithappen by imposing initiative load perpendicular to fractured faces. Con-rod fracturesplitting is precision process technology and the key process of which includesnotching, oriented split and assembling bolt, of which oriented split is the key process.Research work in this dissertation focuses on conrod fracture splitting clampfrom some aspects, such as material, heating treatment and structural parameter, aimto prolong con-rod service life and reliability, and to improve split quality. Clampconsists of pull-rod and splitting block. Some special research of this paper goes asfollows:1. In order to improve the performance and extend the service life of clamp, thispaper takes some condition analysis and a reasonable choice of material and heattreatment process of fracture clamp.2. In the pre-treatment process of finite element analysis to force anddeformation, the Surface Effect Element and characteristic face have been introduced.In addition, another technology processing is for the force of pull-rod to movable splitblock, it is regarded only as forces, rather than incorporates contact stress.3. Analysis to assessment factors and calculation methods of pull-rod structuralparameters have been done to determine the respective value or range, includingwedge angle, cross-sectional area and aspect ratio of straight bar.Considering the self-locking, drop-down force and speed, some certain degreehas been taken for the wedge angle reference value. Otherwise, this paper put forwarda method to preliminary calculation of the cross-sectional area of the pull-rod straightpart. Through the analyses of stress distribution and the difference in X-directiondisplacement with the changes of the aspect ratio, the aspect ratio reference ofcross-sectional area of the pull-rod straight part is given.4. Analysis of Influence of main structural parameters to the stress level anddeformation of the block has been done to determine the primary and secondary order parameters and reasonable range of parameters, including boss height-diameterratio,the axial position of the inside inclined plane and the ratio of boss hole edge toouter diameter. An estimation method how to quickly determine whether the con-rodcan be fractured has been put forward. The strength and stiffness analysis of clampwith oil passage was done.Studies have shown that the boss height-diameter ratio has a significant impacton fracture clamp stress value, in the condition that the ratio of boss hole edge to outerdiameter does not meet the limit. The axial position of the inside inclined plane. Theratio of boss hole edge to outer diameter is the most significant, boss height-diameterratio is second, and the aspect ratio reference of cross-sectional area of the pull-rodstraight part is the last one. On the basis of the relationship of boss hole edge and theouter diameter ratio, an estimation method how to quickly determine whether theconrod can be fractured. Studies have shown that the oil passages impact on clampcan be ignored.