Core bit special for heat-preserving waterproof layer minimally invasive detection

Disclosed is a core bit special for heat-preserving waterproof layer minimally invasive detection. The core bit comprises a drilled core pipe and a core bit body, wherein the core bit body is connected to the left end of the drilled core pipe in a threaded mode. A hexagonal prism at the right end of the drilled core pipe is connected into a hexagon hole of a drilled core pipe connecting piece in a penetrating mode and is integrated with the drilled core pipe connecting piece to constitute a drilling machine connecting piece. A T-shaped sampling piston with a center rod is arranged in a pipe cavity of the drilled core pipe and is in clearance fit with the pipe cavity. A center hole is formed in a plug at the right end of the drilled core pipe. A center rod of the sampling piston is located in the center hole of the drilled core pipe and is in clearance fit with the center hole. The core bit with the outer diameter smaller than 30mm can be designed into a series of products with various sizes and specifications