Core drill bit having a helical tube-shaped drill shaft and a method of manufacturing a helical tube-shaped drill shaft for a core drill bit

摘要

The present invention relates to a core drill bit 10 for forming a drill hole 24 having a drill hole diameter d2 and a drill core 23 having a core diameter d1 in a workpiece 22. The core drill bit 10 has one or a plurality of grinding areas 15. It comprises a cutting portion 11, a drill shaft portion 12 having a tubular drill shaft 16, and a connecting device 13 for detachably or non-removably connecting the cutting portion 11 and the drill shaft portion 12, wherein the tubular drill shaft 16 is a welding spiral tube. Be composed. [Selection diagram] FIG. 1A