Abstract: A dresser supply device of a grinding tool which supplies powdery dresser to a grinding tool having an abrasive grain layer on cutting blade tips, the dresser supply device comprising: an air supply source which supplies air; a dresser supply air pipe including a base end which is connected to the air supply source; a dresser tank which holds the dresser; a dresser supply pipe which connects the dresser tank and the dresser supply air pipe to each other, is smaller in diameter than the dresser supply air pipe at a connecting portion with the dresser supply air pipe, has a first tip inserted and projecting into the dresser supply air pipe, and is located at a space from an inner peripheral surface of the dresser supply air pipe; and an opening-and-closing valve which is provided in the dresser supply air pipe between the connecting portion and the air supply source side.

Abstract: A drilling device is composed so as to drill a drilled object composed of a brittle material with the end of a rotating core bit by using a core bit in which a bit, formed by dispersing and arranging a cemented carbide or super abrasive in a binder phase, is provided on the end of a cylindrical tube, and rotating the core bit around an axis with a direct motor. The drilling device is composed so that the core bit is rotated such that the peripheral velocity at the outer periphery of the bit is 300 m/min or more while the core bit presses against the drilled object at a pressure of 0.6 N/mm2 or more during drilling.

Abstract: A tool, a device, and a method for drilling capable of very easily forming a hole part in a drilled matter by extremely smoothly discharging chips produced at drilled positions so as to maintain an excellent drilling efficiency. By using a drilling tool having a shaft with a spiral groove part formed in the outer peripheral surface thereof and a bit fixed to the tip part of the shaft, the hole part is formed in a drilled matter by rotating the shaft.

Abstract: The present invention relates to an abrasive that decreases the heat generation by a core bit due to boring and allows the boring of a deep hole while maintaining the boring speed even when a deep hole is cut using a dry method. This abrasive contains abrasive grains, particles of anhydrous silica having a particle diameter from 5 nm to 50 nm and silanol groups in the surface thereof, and hydrous resin which discharges water when the hydrous resin is pressed by a core bit or the temperature of the hydrous resin rises. The abrasive 51 is supplied between the distal end of a rotating core bit 11 and a working material 20.