Abstract: An engine piston structure includes: a piston (1); a connecting rod (10) having a small end part (10a) coupled to the piston (1), and having a large end part (10b) coupled to a crankshaft; a piston pin (2) through which the piston (1) and the small end part (10a) of the connecting rod (10) are coupled together and which has a hollow cross section; and at least one dynamic vibration absorber (20) provided inside the piston pin (2) to reduce resonance of the piston (1), the piston pin (2), and the small end part (10a) of the connecting rod (10) in combination with respect to the large end part (10b) of the connecting rod (10) during a combustion stroke.

Abstract: An engine piston structure includes: a piston (1); a connecting rod (10) having a small end part (10a) coupled to the piston (1), and having a large end part (10b) coupled to a crankshaft; a piston pin (2) through which the piston (1) and the small end part (10a) of the connecting rod (10) are coupled together and which has a hollow cross section; and at least one dynamic vibration absorber (20) provided inside the piston pin (2) to reduce resonance of the piston (1), the piston pin (2), and the small end part (10a) of the connecting rod (10) in combination with respect to the large end part (10b) of the connecting rod (10) during a combustion stroke.

Abstract: An aluminum material for use as an electronic material is produced by a method comprising the steps of melting aluminum inevitably containing U and Th to obtain molten aluminum, holding the molten aluminum heated at a temperature above the solidification temperature thereof, and immersing a hollow rotary cooling member in the molten aluminum and rotating the cooling member in the molten aluminum while maintaining the surface of the cooling member at a temperature lower than the solidification temperature by supplying a cooling fluid to the interior of the cooling member to cause aluminum to crystallize out on the surface of the cooling member with reduced U and Th contents.

Abstract: A metal having a high purity is prepared by immersing a hollow rotary cooling member in a molten metal containing eutectic impurities and rotating the cooling member while supplying a cooling fluid to the interior of the cooling member, whereby the high-purity metal is caused to crystallize out on a metal deposition area of the peripheral surface portion of the cooling member present under the surface of the molten metal, the metal deposition area being the peripheral surface of at least a part of the entire portion, present under the melt surface, of the member. When the purified metal is caused to crystallize but by rotating the cooling member, a flow of molten metal having a downward velocity component is produced in the vicinity of an upper part of the entire portion, present under the melt surface, of the cooling member.

Abstract: A metal having a high purity is prepared by immersing a hollow rotary cooling member in a molten metal containing eutectic impurities and rotating the cooling member while supplying a cooling fluid to the interior of the cooling member, whereby the high-purity metal is caused to crystallize out on a metal deposition area of the peripheral surface portion of the cooling member present under the surface of the molten metal, the metal deposition area being the peripheral surface of at least a part of the entire portion, present under the melt surface, of the member. When the purified metal is caused to crystallize out by rotating the cooling member, a flow of molten metal having a downward velocity component is produced in the vicinity of an upper part of the entire portion, present under the melt surface, of the cooling member.

Abstract: An apparatus for treating a molten metal comprises a vertical post, a treating container disposed at one side of the post and having an opening at its upper end for containing the molten metal, a horizontal suspending arm mounted at its base end on the post upwardly and downwardly movably and rotatable in a horizontal plane, a vertical rotary shaft suspended from the arm and having a treating gas channel internally extending therethrough longitudinally, a bubble releasing-dispersing rotor provided at the lower end of the rotary shaft and having in its bottom surface a treating gas outlet in communication with the gas channel, the rotor being movable into and out of the container through the opening, and at least one baffle suspended from the arm and movable into and out of the container through the opening for preventing eddying and waving.

Abstract: Hydrogen gas and non-metallic inclusions are removed from molten aluminum by a process comprising the steps of rendering the portion above the surface of molten aluminum in a treating vessel where the molten aluminum is placed, an atmosphere of air having a lower dew point than that of the atmosphere and maintaining it as it is, introducing a treating gas into the molten aluminum, and removing floating non-metallic inclusions and treating gas containing hydrogen gas from the surface of the melt.

Abstract: Crude silicon is purified by melting the crude silicon, maintaining the molten silicon above the solidification temperature thereof in an inert gas atmosphere, and rotating a hollow rotary cooling member as immersed in the molten silicon while introducing a cooling fluid into the cooling member to cause high-purity silicon to crystallize on the outer surface of the cooling member.

Abstract: Hydrogen gas and nonmetallic inclusions are removed from molten aluminum by a method comprising applying over the surface of molten aluminum in a container a mixture of at least one compound selected from the group consisting of boron oxides, boric acids and boric acid compounds and a flux comprising a halgen salt, introducing a treating gas into the molten aluminum, and removing the hydrogen gas-containing treating gas and nonmetallic inclusions rising to the surface of the molten aluminum.

Abstract: A device comprising a rotary shaft to be disposed in a liquid substantially vertically and rotatable about its own axis, the rotary shaft having a gas channel extending therethrough axially of the shaft, and a rotor fixed to the lower end of the rotary shaft and having at its bottom surface a gas discharge outlet communicating with the gas channel. The rotor is formed in its bottom surface with radial grooves extending from the gas outlet to the peripheral surface of the rotor and each having an open end at the peripheral surface. A recess is formed in the peripheral surface between the open ends of immediately adjacent grooves and has an open lower end at the bottom surface. When the rotary shaft is rotated in a liquid while supplying a gas to the gas channel of the shaft, the gas flows out from the discharge outlet into the radial grooves and is released from the open ends of the grooves at the peripheral surface into the liquid in the form of finely divided bubbles.

Abstract: Hydrogen gas and non-metallic inclusions are removed from molten aluminum by a process comprising the steps of maintaining an atmosphere containing BF.sub.3 gas in a treating vessel above the surface of molten aluminum placed therein, introducing a treating gas into the molten aluminum, and removing floating non-metallic inclusions and treating gas containing hydrogen gas from the surface of the molten aluminum.