Core drill

Abstract

Provided is a core drill which is capable of drilling a hole and consumes small electric power consumption when the core drill is applied to a codeless type electric drill. A core body 2 is formed to have a small thickness. An outer peripheral surface of a tip end portion of the core body has a tapered surface which is thinner toward the tip end and is edged at the tip end. Recesses 2B are formed at an opening peripheral edge of the tip end portion to attach cutting chips. A portion of the core body which is adjacent to a forward portion of each of the recesses in the rotational direction is bent radially inward. Each of the cutting chips 3 is configured to have a stepped portion when viewed from the bottom such that a radially inner portion 3a of a forward end portion 3 protrudes forward in the rotational direction and a radially outer portion of the forward end portion 3 recedes rearward in the rotational direction. Each of the cutting chips 3 is configured to have a stepped portion when viewed from the bottom such that a radially inner portion of a rearward end portion is located forward in the rotational direction and a radially outer portion of the rearward end portion is located rearward in the rotational direction. The cutting chips 3 are attached to the core body 2 in such a manner that a forward end portion of each of the recesses is located at the radially inner portion 3a of the forward end portion of the cutting chip in the rotational direction, and the connecting surface connecting a radially outer portion to a radially inner portion of a rearward end portion in the rotational is in contact with a portion of the outer peripheral surface adjacent to a rearward portion of the recess in the rotational direction.

Description

technical field [0001] The present invention relates to a coring drill bit for drilling large-diameter objects such as wood, resin materials, metal materials or composite materials of the above materials, and in particular to a coring drill bit suitable for a rechargeable mobile electric drill. Background technique [0002] Currently, core drills are used when drilling large-diameter holes in objects to be drilled. The core drill has: a cylindrical core body, a shank positioned above the core body to be attached to a chuck disposed on a drive shaft, and a cutter disposed at a distance from each other on the front end peripheral portion of the core body. knives. Also, a chip discharge port for discharging cutting chips from the base end side of the core drill is formed in front of the rotation direction of the portion of the core body to which the cutting tool is mounted. In addition, a helical (or inclined) discharge groove for conveying chips to the base end is provided o...

AI Technical Summary

Problems solved by technology

[0008] However, compared with the "corded electric drill" that supplies power from an electrical outlet via a power cord, the cordless electric drill has problems such as low rotational torque, and the drilling time is limited by the battery capacity.

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