The present invention provides a twist drill. A cone portion is provided at a front end of the operating portion, and an exterior surface of the operating portion is provided with a spiral flute for shunting cutting chips. The exterior surface of the cone portion is provided with a plurality of composite cutting blade groups which are sequentially enlarged in diameter from the front end to the rear end of the cone portion. The cone portion is provided with a top blade on the tip. In use, the top blade is used for positioning, and the cutting process is carried out by the top blade and the composite cutting blade groups.

A core drill bit 1 includes a tubular shaft 12, a mounting platform 31 provided on a proximal end of the tubular shaft 12 for mounting the core drill bit on a power tool 26, and an annular cutting section 2 provided with abrasive cutting segments 3 arranged at a distal end of the tubular shaft 12. A first transponder 24 is provided at the distal end of the tubular shaft 12. A repeater 28 is provided comprising a second transponder 29 at the proximal end of the tubular shaft 12, an antenna 33 facing the first transponder 24, and a wired connection 34 between the antenna 33 and the repeater 28.

An apparatus for selectively removing material from both an inner and outer circumference of an end of a tubular workpiece includes a cylindrical outer frame. A blade holder is affixed to the outer frame. The blade holder has a conical configuration with a base located adjacent a first rim of the outer frame and an apex located adjacent a second rim of the outer frame. At least one ID blade is carried by the blade holder and has an ID cutting edge oriented radially outward. At least one OD blade is carried by the blade holder and has an OD cutting edge oriented radially inward. A motive cap has a rim-coupling feature configured for selective engagement sequentially with the first and second rims of the outer frame, to selectively provide rotational motion to the outer frame and thus indirectly to the blade holder.

A step drill and a manufacturing method for a step drill in which cutting performance of a cutting edge of a step portion can be enhanced are provided. A groove includes a first ground portion forming an area embracing a second cutting edge of the step portion and a second ground portion forming an area on the heel side of the step portion relative to the first ground portion. Therefore, a convex blade part can be formed on a first cutting edge by performing grinding with the first ground portion and the second ground portion intersecting with each other. That is, it is possible to form the second cutting edge into a desired shape during grinding of the first ground portion. Therefore, cutting performance of the second cutting edge can be enhanced.

A step drill and a manufacturing method for a step drill in which cutting performance of a cutting edge of a step portion can be enhanced are provided. A groove includes a first ground portion forming an area embracing a second cutting edge of the step portion and a second ground portion forming an area on the heel side of the step portion relative to the first ground portion. Therefore, a convex blade part can be formed on a first cutting edge by performing grinding with the first ground portion and the second ground portion intersecting with each other. That is, it is possible to form the second cutting edge into a desired shape during grinding of the first ground portion. Therefore, cutting performance of the second cutting edge can be enhanced.

The present invention provides a twist drill. A cone portion is provided at a front end of the operating portion, and an exterior surface of the operating portion is provided with a spiral flute for shunting cutting chips. The exterior surface of the cone portion is provided with a plurality of composite cutting blade groups which are sequentially enlarged in diameter from the front end to the rear end of the cone portion. The cone portion is provided with a top blade on the tip. In use, the top blade is used for positioning, and the cutting process is carried out by the top blade and the composite cutting blade groups.

The present invention provides a twist drill. A cone portion is provided at a front end of the operating portion, and an exterior surface of the operating portion is provided with a spiral flute for shunting cutting chips. The exterior surface of the cone portion is provided with a plurality of composite cutting blade groups which are sequentially enlarged in diameter from the front end to the rear end of the cone portion. The cone portion is provided with a top blade on the tip. In use, the top blade is used for positioning, and the cutting process is carried out by the top blade and the composite cutting blade groups.

The present invention provides a twist drill. A cone portion is provided at a front end of the operating portion, and an exterior surface of the operating portion is provided with a spiral flute for shunting cutting chips. The exterior surface of the cone portion is provided with a plurality of composite cutting blade groups which are sequentially enlarged in diameter from the front end to the rear end of the cone portion. The cone portion is provided with a top blade on the tip. In use, the top blade is used for positioning, and the cutting process is carried out by the top blade and the composite cutting blade groups.

An apparatus for selectively removing material from both an inner and outer circumference of an end of a tubular workpiece includes a cylindrical outer frame. A blade holder is affixed to the outer frame. The blade holder has a conical configuration with a base located adjacent a first rim of the outer frame and an apex located adjacent a second rim of the outer frame. At least one ID blade is carried by the blade holder and has an ID cutting edge oriented radially outward. At least one OD blade is carried by the blade holder and has an OD cutting edge oriented radially inward. A motive cap has a rim-coupling feature configured for selective engagement sequentially with the first and second rims of the outer frame, to selectively provide rotational motion to the outer frame and thus indirectly to the blade holder.

A tapered countersink drill bit includes at least two screwing knifes and at least one two screwing trenches and a rod body; a length of an edge of the left lateral side of each screwing knife being shorten than that of an edge of the right lateral side thereof; each screwing knife including a front drilling head; a tapered portion formed at a backside of the front drilling head; a rear drilling head formed at a backside of the tapered portion; the screwing angle of each screwing knife being identical from the front drilling head to the rear drilling head; and a screwing angle of each screwing trench being identical from the front drilling head to the rear drilling head; a width between two adjacent knifes at a front end of the rear drilling head being longer than a width between two knifes at rear ends of two rear drilling head.