Apparatus for punching anchor bolt insertion hole

An apparatus for punching anchor bolt insertion hole, the apparatus comprising:

• a hammer drill adapter configured to be connected to a hammer drill exposing a drill bit so that the exposed drill bit passes through the hammer drill adapter and so that the drill bit is movable in a vertical direction and in an inclined direction in a predetermined space,
• the hammer drill adapter comprising:
• a first body comprising an upper cylindrical body and a lower cylindrical body, the upper cylindrical body being configured to be coupled to the hammer drill, the lower cylindrical body having female screw thread on an inner surface of the lower cylindrical body, a diameter of the lower cylindrical body is smaller than the upper cylindrical body;
• a cylinder shaped drill bit fixing portion having a male screw thread on an upper outer surface so as to be engaged with the female screw thread of the first body, an intermediate protrusion on an outer surface of the cylinder shaped drill bit fixing portion spaced from the male screw thread by a predetermined length;
• an inclined driving portion having a center and a spherical upper surface with an annular protrusion formed in the center, a vertical walled side surface with the same radius in cross section, and a detachable circular plane lower surface in contact with a bottom of the vertical walled side surface, and wherein a through hole is formed in an inner space of the inclined driving portion created by the upper surface, the side surface and the lower surface so that the intermediate protrusion of the drill bit fixing portion is located, and a first spring elastically supporting the intermediate protrusion of the drill bit fixing portion is located on an upper surface of the circular plane forming a lower surface toward the inner space, a descending hanging portion of the intermediate protrusion of the drill bit fixing portion enclosing the spring is formed in a lower height than the first spring;
• and
• a second body comprising a cover portion comprising an upper inner surface having a radius of curvature equal to or larger than that of the spherical surface of the inclined driving portion upper surface and an opening of a predetermined size so that the spherical upper surface of the inclined driving portion is stopped, a side inner surface having a cylindrical wall so that the inclined driving portion is movable in the vertical direction, and a cylindrical wall bottom portion having been extended to a predetermined size so as to have a radius of curvature equal to or greater than the spherical upper surface of the inclined drive portion;
• a cylindrical supporting portion having an inclined cylindrical space coupled to the cover portion, wherein an inner ring-shaped support portion is formed inside the inclined cylindrical space, a second spring is disposed on the inner ring-shaped support portion to elastically support the inclined driving portion, and the inclined driving portion is located in the inclined cylindrical space between the cover portion and the inner ring-shaped support portion;
• and a lower surface assembly portion having an inclined driving portion support cylinder and an inclined bearing, the inclined driving portion support cylinder being located inside the inner ring-shaped support portion and stopping the lower surface of the inclined driving portion at a predetermined point while making the drill bit pass through the lower surface of the inclined driving portion, the inclined bearing maintaining the center of the drill bit fixing portion to the cylindrical support portion when the inclined driving portion support cylinder moves in an up and down direction and an inclined direction,
• wherein the spring constant of the first spring is greater than the spring constant of the second spring.