Anchor bolt
AssigneeFujibyora Co., Ltd.
InventorsShoichi Tajima, Kouji Fujiwara
Life of this patent
Estimating the term…
Abstract
An anchor bolt consisting of a shank screwed into a bore in a structural body made of concrete etc. having a screw thread with notches, and a root of thread between the screw thread. The entering flank and the trailing flank of the screw thread are defined by respective angles of inclination .alpha. and .beta. formed therefrom to the axis of the shank, the angle .beta. being smaller than the angle .alpha.. The root of screw is constituted by a carrying portion formed immediately after the trailing flank toward the unscrewing direction, and a tapered surface formed from the carrying portion to the root portion of the entering flank of the following screw thread, gradually increasing in diameter theretoward.
Claims10
An anchor bolt comprising a shank for being screwed into a bore formed in a structural body made of concrete and the like, a head portion for rotating said shank, and a screw portion provided along said shank and including a screw thread as an constituent thereof, said screw thread having an entering flank facing the screwing direction, a trailing flank facing the unscrewing direction and a plurality of notches on a crest of said screw thread, wherein:
- said screw thread 4 has an angle of inclination .beta. from said trailing flank 7 to an axis L of said shank being smaller than the angle of inclination .alpha. from said entering flank to said axis L;
- and
- a root 5 of the thread formed along said shank between turns of said screw thread is provided with a carrying portion 11 formed in a position immediately adjacent to said trailing flank that tapers in the unscrewing direction, and a tapered surface which gradually increases in diameter from said carrying portion to a root portion X of the entering flank of a following turn of the screw thread.
An anchor arrangement having a structural body that is made of concrete or like material with a bore formed therein and an anchor bolt, said anchor bolt comprising a shank screwed into the structural body, a head portion for rotating said shank, and a screw portion provided along said shank and including a screw thread as an constituent thereof having an entering flank facing the screwing direction, a trailing flank facing the unscrewing direction and a plurality of notches on a crest of said screw thread, wherein:
- said screw thread 4 has a crest diameter which is larger than an inside diameter of said bore, and a diameter of at least one of a root portion X of said entering flank 6 and a root portion Y of said trailing flank 7 being equal to said inside diameter of said bore 10 for constituting guide means for screwing said shank into said bore 10;
- said entering flank 6 is defined by an angle of inclination .alpha. therefrom to an axis L of said shank, while said trailing flank 7 is defined by an angle of inclination .beta. therefrom to said axis L, said angle of inclination .beta. being smaller than said angle of inclination .alpha. for increasing a pull-out resistance of the trailing flank 7 relative to the structural body, while enabling the entering flank 6 to retain the thickness and strength of the screw thread;
- and
- a root 5 of the thread between turns of said screw thread is provided with a carrying portion 11 which decreases in diameter continuously from said root portion Y and has a diameter which is smaller than said inside diameter of said bore, and a tapered surface 12 which gradually increases in diameter from said carrying portion to the root portion X of the entering flank of a following turn of the screw thread.
Dependencies are inferred from the claim text.