Abstract: A drill capable of performing high-quality drilling machining on a material which is hard to be cut such as CFRP is provided. The drill includes a drill body 4 having a shank portion 2 at a rear side of the drill main body and a cutting portion 3 at a front side of the drill main body, a first land A to a fourth land D at the cutting portion 3, a first cutting portion groove 5a to a fourth cutting portion groove 5d provided between the lands of the first land A to the fourth land D, a pilot blade 6 formed at the tip of the cutting portion 3, a diameter-enlarging spiral thread portion 9 continuously following the pilot blade 6, a finished spiral thread portion 12 continuously following the diameter-enlarging spiral thread portion 9, a diameter-enlarging spiral blade portion 18, and a finishing spiral blade portion 19.

Abstract: A drill capable of performing high-quality drilling machining on a material which is hard to be cut such as CFRP is provided. The drill includes a drill body 4 having a shank portion 2 at a rear side of the drill main body and a cutting portion 3 at a front side of the drill main body, a first land A to a fourth land D at the cutting portion 3, a first cutting portion groove 5a to a fourth cutting portion groove 5d provided between the lands of the first land A to the fourth land D, a pilot blade 6 formed at the tip of the cutting portion 3, a diameter-enlarging spiral thread portion 9 continuously following the pilot blade 6, a finished spiral thread portion 12 continuously following the diameter-enlarging spiral thread portion 9, a diameter-enlarging spiral blade portion 18, and a finishing spiral blade portion 19.

Abstract: A cutting tap comprises a threaded portion including a lead whose thread diameter gradually decreases toward a front end of the lead, a complete thread portion continued from the lead, and four flutes arranged at equal intervals in a circumferential direction. In the cutting tap, a first cutting edge portion for processing a prepared hole is formed at a front end surface of the lead, and a second cutting edge portion for finishing a minor diameter of an internal thread is formed in a part of an outer periphery of the complete thread portion, the second cutting edge portion being one or more pitches long. The cutting tap can perform processing of a prepared hole, tapping, and finishing of a minor diameter by a single step, and can also perform tapping even if a prepared hole for an internal thread is a blind hole or the like and does not have enough space.

Abstract: It is an object of the invention to provide a thread-forming tap to which a chamfer can easily be mounted, and a general threading method. The thread forming tap of the invention has a threaded portion comprising a tapered chamfer and a parallel threaded portion which is formed continuously with the chamfer. A depth of root of the chamfer is set equal to that of a root of the parallel threaded portion constantly.

Abstract: A cutting tap comprises a threaded portion including a lead whose thread diameter gradually decreases toward a front end of the lead, a complete thread portion continued from the lead, and four flutes arranged at equal intervals in a circumferential direction. In the cutting tap, a first cutting edge portion for processing a prepared hole is formed at a front end surface of the lead, and a second cutting edge portion for finishing a minor diameter of an internal thread is formed in a part of an outer periphery of the complete thread portion, the second cutting edge portion being one or more pitches long. The cutting tap can perform processing of a prepared hole, tapping, and finishing of a minor diameter by a single step, and can also perform tapping even if a prepared hole for an internal thread is a blind hole or the like and does not have enough space.

Abstract: It is an object of the invention to provide a thread-forming tap to which a chamfer can easily be mounted, and a general threading method. The thread forming tap of the invention has a threaded portion comprising a tapered chamfer and a parallel threaded portion which is formed continuously with the chamfer. A depth of root of the chamfer is set equal to that of a root of the parallel threaded portion constantly.

Abstract: A tap having a reamer edge which is provided at a chamfer part, so that when the thread forming tap is pulled out after the internal thread is formed, a seam portion present at the crest of the internal thread is cut off, whereby even in a blind hole, formation of internal thread and cutting of the seam portion are performed in a single process, and formation of an internal thread and processing of an inside diameter portion are achieved in a single process to obtain concentricity in line with each other. Further, even if there is a deviation in diameter of the hole before threading, the inside of the internal thread is processed to a constant value.