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This paper describes an experimental method to predict the rolling contact fatigue life of a crankpin in a market vehicle engine. The fatigue life up to pitting was evaluated by two laboratory tests including a fatigue life measurement using a ball-on-disk test machine and a crankpin durability measurement by an engine bench test. The surface observation after the tests revealed that the surface dent triggers pitting in both tests. The Weibull plot of the percent failure vs. cycle to failure as a function of the contact stress was presented. In order to directly evaluate the effect of the contact stress on the lifetime, the lifetime values measured at L50 are plotted in the diagram showing the contact stress vs. cycle to failure. The obtained relation can predict the lifetime under the controlled condition in which the number of maximum torque points is countable.

A monolithic cylinder block using a hyper-eutectic Al-Si alloy provides superior cooling performance and light weight. Through the mechanical recessing process a soft honing stone polishes the aluminum matrix away and exposes the primary-Si crystal. This is a good way to obtain superior tribological properties at the bore surface. To reveal the basic mechanism of the mechanical recessing process, this research used experimental recess testing and a boundary element method calculation simulating the actual honing process. A pin-on-disk type recess test using an elastic polyurethane pin and an A390-alloy disk was carried out. An increased number of rubbings exposed the primary Si crystals from the aluminum matrix. The exposure height of the Si particle initially increased but stayed constant to a critical exposure height above the increased rubbing number of 500. The mathematical simulation revealed that the provided pressure on the Si particle determined the critical exposure height.

A monolithic aluminum block using a newly developed Al-20%Si alloy was made by a vacuum die-casting process. The bore surface design was a sleeveless type with uniformly dispersed primary-Si crystals around 20μm. The die-casting technology consists of a highly airtight die with two series of evacuation systems. The vacuum level in the die cavity was determined to be as low as 5kPa. The gas content of the block was found to be as low as 5cc/100g Al, which has enabled T6 heat treatment. The die cavity temperature was carefully controlled to generate a fine dispersion of primary-Si crystals. The engine testing has proved that the bore wall temperature is 30 K lower than that of the aluminum block enclosing a press-fitted cast iron liner. The superior cooling performance has decreased the oil consumption value to one half that of the aluminum block enclosing a cast iron liner.

A high-quality die-casting technology has been developed for lightweight aluminum frame structures that produces high-strength aluminum parts that are also weldable. This new technology has been used in casting frames for motorcycles and snowmobiles and has enabled improved frame designs with far fewer component parts than was possible before. This die-casting technology also results in a significant reduction in energy consumption during the manufacturing process.

The present work was intended to increase the rolling-contact fatigue life of the crank pin for a motorcycle. The small motorcycle uses a needle roller bearing at the big end of the connecting rod. The needle roller exerts high Hertzian stress on the crank pin. This stress sometimes causes rolling-contact fatigue failure such as pitting. The contaminated oil accelerates the rolling-contact fatigue failure. In order to increase the life of the crank pin, not only the quality of the steel but also the casehardening treatment plays an important role. In the present work, a high quality Cr-Mo steel containing oxygen concentration below 10 ppm was chosen as the base steel. The rolling-contact fatigue life was compared in four types of casehardening: normal carburizing, carbonitriding, super-carburizing and super-carbonitriding. A thrust-type testing machine was used during these comparison tests.

Hard anodic oxide coating (hard anodizing) technology giving hardness values above HV300 was developed for a piston alloy containing a high Cu concentration (Al-12%Si-4Cu-0.5Mg). This technology was developed to improve the result that the anodic oxide coating in a sulfuric acid bath on the alloy can give hardness values as low as HV200. The combination of mixed acid electrolytes (40gL-1 oxalic acid and sulfuric acid less than 150gL-1) and periodic reverse electrolyzing enables the piston-ring groove to form a hard anodic oxide coating film having hardness values above HV300, coating thickness of 20 μm, and surface roughness of Ra 2.0μm. This mixed acid electrolyzing was found to prevent the electrochemical dissolution of Cu. The periodic reverse waveform cools the piston-ring groove to prevent burning.