Papers by Keyword: Fracture Splitting

Abstract: The relationship between microstructure and mechanical properties of 36MnVS4 steel was studied. Different prior austenite grain sizes were obtained by austenitizing at 850, 950 and 1050 °C, respectively, and different ferrite contents were obtained by different cooling rates. Austenitizing temperature mainly influenced the grain size. With the austenitizing temperature increasing, grain size increased and the phase transformation starting temperature increased. Also, the strength increased and the plasticity and toughness decreased. Cooling rate mainly influenced the microstructure percentage. With the cooling rate increasing, ferrite percentage decreased and pearlite percentage increased. And meanwhile, the strength increased and ductility and toughness decreased. Microstructure had a significant influence on fracture splitting properties. With the grain size increasing, fracture splitting properties were markedly improved. With the ferrite percentage increasing and pearlite percentage decreasing, fracture splitting properties were worsened.

Abstract: Connecting rod fracture splitting is a novel connecting rod big end separation precision machining technology. It has become one of the critical technologies in engine production in developed countries. By studying and analyzing the splitting process theory, affecting factors on splitting quality and the expansion force ratio, finite element analysis was conducted by using modern engineering software. Upon design and fabrication a testing device, lots of experiments were carried out. Experiment results show, the study method is effective, the splitting quality can be obtained by homemade equipment. The same equipment can be used for varying temperature and different material splitting analysis in the future.

Abstract: The fracture surface of con-rod is difficult to be quantitatively described due to its indented macro morphology. Thus, the range of fracture surface defect dimension has no uniform standard. In order to solve this question, 3D software about the digital fracture surface reconstruction was developed by combining the fracture splitting technology of con-rod with reverse engineering, which realized the reproduction of its morphology and completed the real area calculation of the surface. The results show that the fracture surface area processed by fracture splitting is 13.1% larger than that of the plane processed by machining. It represents that the defect dimension range of fracture surface is improved compared to empirical value without reducing the bearing capacity and usability.

Abstract: The effect of starting notch machining methods on fracture splitting of connecting rod was studied by axial tensile tests with single edge notch. The axial tensile specimens were made of the high carbon microalloyed steel (C70S6) which is now most widely used by the connecting rod of fracture splitting. The single edge notch of axial tensile specimens were respectively machined by laser notch、wire cut electrical discharge and broaching. The notch tip plastic deformation of specimens was compared by the fractography. The experimental results indicate that the specimens with laser notch can be fractured by the smallest axial tensile load which is respectively about 20% and 30% smaller than the fracture load of the specimens by wire cut electrical discharge and broaching. Considering the rich micro-local crack transformation hardened zones around the notch by laser the paper present the equivalent critical stress intensity factor KIcL which can be used to calculate the fracture load with laser notch.

Abstract: The fracture splitting (FS) method is a bran-new processing technique in the automobile engine connecting rod manufacturing industry, FS is one of three pivotal working procedures, and press speed is one of the key influence factors of FS process. In order to realize parameters of press speed and pull cylinder working pressure, dynamic simulation of hydraulic system has been carried out. Simulation results indicated that press speed of pull cylinder was about 130mm/s, which was between 120mm/s and 150mm/s that was not only good for controlling FS quality, but also not leading irrational design of hydraulic system. The working pressure of pull cylinder was between 10MPa and 14MPa, which was suitable for FS processing. The hydraulic system of FS machine can satisfy the basic requirements of connecting rods FS process. This paper has provided reliable theoretic basis for the design of FS machine for connecting rods.

Abstract: The present requirements for the connecting rod are indicated and the fracture splitting (FS) technologies for constructing the big end boss are reviewed. Two possibilities of FS for a high strength Cr-Mo steel and Ti alloys were discussed. The carburized quench-temper FS connecting rod has a superior fatigue strength with a high dimensional accuracy at the big end boss. The possibility of using a titanium FS connecting rod was examined and proposed.

Abstract: Splitting force is the key to the process of fracture splitting connecting rod. In this paper, numerical simulation is made in the process of fracture splitting Jetta car connecting rod by using software MSC.MARC. Through analysis, the curve between J integral and splitting force is established. According to the experiential formula of impact toughness and fracture toughness, critical J integral ( JIC ) can be achieved. After getting JIC , the splitting force can be determined by linear interpolation method and verified by tensile experiment and the error is below 1%. It is proved that this method can also used to analyze other kinds of connecting rods with different materials.