Patent ID: 7980801

Claim:
A screw comprising: a screw body having a male screw portion that is formed for being screw fastened into a corresponding screw hole and a top hat portion that is integrally formed to be conjoined to one end of the male screw portion, the top hat portion having a top end surface formed on one end of the top hat portion, all of the top end surface being a flat surface; a screw head member that has: a surface having a slot which corresponds with and is capable of coupling with a torque generating tool, the slot being used for transmitting to the top hat portion a running torque from the torque generating tool that generates the running torque required for screw fastening the male screw portion into the screw hole; and a base end surface formed to correspond to the form of the top end surface of the top hat portion, all of the base end surface being a flat surface; and an adhesive solidification layer that bonds the top end surface of the top hat portion and the base end surface of the screw head member to couple the top hat portion and the screw head member, wherein the adhesive solidification layer covers all of the top end surface of the top hat portion and all of the base end surface of the screw head member, wherein the top hat portion has an upper-half region expansion taper portion having a truncated cone shape, one end of the upper-half region expansion taper portion is the one end of the top hat portion, all of the expansion taper portion gradually becomes larger in diameter toward the one end of the upper-half region expansion taper portion, and wherein the adhesive solidification layer is a hardened adhesive, and the adhesive has a fracture strength sufficient for transmitting running torque from the screw head member to the screw body in a steady state and has a property of exfoliating from the top end surface and the base end surface to thereby expose the flat surface of the top end surface to the outside when a warm water heat treatment is applied.