Teruie Takemasu

Investigation of metal flow and preform optimization in flashless forging of a connecting rod

Abstract In conventional hot forging of connecting rods, the material wasted to the flash accounts approximately 20 to 40% of the original workpiece. In order to reduce the cost of forged products, the forging must be performed in a closed cavity to obtain near-net or net shape parts. In flashless forging, the volume distribution of the preform must be accurately controlled to avoid overloading the dies and to fill the cavity. Additionally, the preform must be simple enough to be mass produced. This study deals with the design of the optimum preform to forge a connecting rod without flash. The initial preform design was obtained from physical modeling experiments. The optimization of this preform was found through 3D FEM process simulations. The advantage of performing simulations is that no tooling has to be built and the number of experimental tryouts can be significantly reduced. A preform optimization methodology was derived for this investigation.

Establishment of Laser Sintering Technique for Titanium Powder

This paper investigates the characteristic of single-layered and multi-layered compacts made by selective laser sintering using titanium powder. The surface texture and tensile strength were investigated by using single-layered compacts. There were few defects in surface of specimen laser sintered in vacuum, and the roughness was smoother than that of the specimen laser sintered in argon. Maximum tensile strength of single-layered compact laser sintered in vacuum was about 200MPa. The shrinkage and mechanical strength were investigated by using multi-layered compacts. There was a unique tendency in the shrinkage of multi-layered compacts, which the density was around 75% and the adhesive bonding was not observed between layers, resulted in 70MPa of maximum bending strength and 50MPa of maximum tensile strength.

Coining of Microgrooves on Injection Molded Materials

The final objective of this study is to establish the optimized manufacturing method of herringbone microgrooves for fluid dynamic spindles. In this article, two kinds of fundamental coining experiments of a simple indentation are carried out to create microgrooves of 5∼10μm depth. In order to compare the coining performance, two kinds of materials are used. One is an austenitic stainless steel (SUS303) of the wrought material and the other is also an austenitic stainless steel (SUS304L) of metal injection molded (MIM) material which has 5% porosity. In experiment-1, a flat head punch with three micro projections of 10μm height is pushed into a hexahedral specimen with or without the ultrasonic vibration. The groove depth of the MIM material increases in proportion to the punch load in the static indentation and its maximum value is about 80% larger than that of the wrought material. The imparting of the ultrasonic vibration is effective to increase the amount of groove depth especially for the MIM material under the lower punch load. In experiment-2, a circular punch and a circular anvil are statically pushed into a cylindrical specimen to produce 18 parallel grooves with an equal pitch in the circumferential direction. The groove profiles become almost uniform and the burr formation at tips of groove shoulder is effectively suppressed under the excessive amount of die indentation.

Indentation of a rack-shaped punch.

Plate strain indentation of lead specimens of finite thickness is investigated experimentally and theoretically for the purpose of its application to the rough forming of large gear teeth. The metal flow is examined by visioplasticity during indentation. The proposed slip line field solutions and upper bound solutions explain well the observed metal flow and the actual load diagrams. It is found that the teeth can be formed with a precise pitch by successive indentation using a punch with double teeth.