Abstract: Even in the case where, due to distortion (undulation) or the like of an end surface of an adjusting screw abutting on a valve stem end, there exists a non-linear undulation movement amount in a movement amount of the end surface with respect to a rotation return angle of the adjusting screw, the undulation movement amount is continuously measured, and a screw return movement amount based on a screw pitch and on the rotation return angle is continuously calculated, and, when a total movement amount of the undulation movement amount and the screw return movement amount has attained a prescribed clearance, return rotation is ended.

Abstract: The present disclosure relates to a shot used for blast processing, the shot being made of an iron-based alloy containing C: 0.20 to 0.50% by mass, Si: 0.50 to 1.10% by mass, and Mn: 0.50 to 1.15% by mass as additive elements, in which a mass ratio of C to Si is 0.30 to 0.75, a mass ratio of C to Mn is 0.30 to 0.75, and a mass ratio of Si to Mn is 0.70 to 1.60, and a Vickers hardness of the shot is HV 400 to 800.

Abstract: Even in the case where, due to distortion (undulation) or the like of an end surface of an adjusting screw abutting on a valve stem end, there exists a non-linear undulation movement amount in a movement amount of the end surface with respect to a rotation return angle of the adjusting screw, the undulation movement amount is continuously measured, and a screw return movement amount based on a screw pitch and on the rotation return angle is continuously calculated, and, when a total movement amount of the undulation movement amount and the screw return movement amount has attained a prescribed clearance, return rotation is ended.

Abstract: A cast steel shot media for performing a blasting treatment, including, at a weight ratio, 0.8% or more and 1.2% or less of C, 0.35% or more and 1.2% or less of Mn, and 0.4% or more and 1.5% or less of Si, in which a remainder has a hyper-eutectoid composition including Fe and inevitable impurities, and the cast steel shot media has a structure having a fine pearlite structure as a main constituent.

Abstract: A method and device for producing shots are provided where the yield is improved. In a space (5) for forming molten drops, which space is surrounded by water (1) in a tank (20), by a cover (3) to cover an area surrounding a disc (2) that is located above the water and rotates, and by a tundish (4) that penetrates through the cover, a gas is discharged though an opening (6) that is formed in the cover and the film (9) of the water is formed on the inner surface of the cover. The molten metal (10) flows through the hole (11) in the bottom of the tundish to be supplied onto the rotating disc. The molten drops are formed by centrifugal force from the molten metal that has been supplied to the disc. Then the molten drops are caused to collide with the film of the water on the inner surface of the cover, to be divided into the droplets that are smaller than the molten drops. The droplets are cooled and solidified.

Abstract: A cast steel shot media for performing a blasting treatment, including, at a weight ratio, 0.8% or more and 1.2% or less of C, 0.35% or more and 1.2% or less of Mn, and 0.4% or more and 1.5% or less of Si, in which a remainder has a hyper-eutectoid composition including Fe and inevitable impurities, and the cast steel shot media has a structure having a fine pearlite structure as a main constituent.

Abstract: A method and device for producing shots are provided where the yield is improved. In a space (5) for forming molten drops, which space is surrounded by water (1) in a tank (20), by a cover (3) to cover an area surrounding a disc (2) that is located above the water and rotates, and by a tundish (4) that penetrates through the cover, a gas is discharged though an opening (6) that is formed in the cover and the film (9) of the water is formed on the inner surface of the cover. The molten metal (10) flows through the hole (11) in the bottom of the tundish to be supplied onto the rotating disc. The molten drops are formed by centrifugal force from the molten metal that has been supplied to the disc. Then the molten drops are caused to collide with the film of the water on the inner surface of the cover, to be divided into the droplets that are smaller than the molten drops. The droplets are cooled and solidified.