PURPOSE: To increase strength in addition to the original characteristic of a FRP-made lock bolt, and use a surface as its screw as it is.
CONSTITUTION: In a FRP-made lock bolt which consists of a long fibrous fiber and thermosetting resin, a filamentous fiber 2 is fastened on the surface of pole shaped long fibrous fiber in which thermosetting resin 2 is impregnated and which is continued in longitudinal direction by winding spirally and integratedly at an interval in outer circumferential axis direction. A spiral recessed shaped groove part 4 is formed on the filamentous fiber 2 part which is wound and fastened, and a projection shaped gabled part 3 is formed between clearances of adjacent spiral recessed shaped groove parts 4. the height difference between the projection shaped gabled part 3 and the recessed shaped groove part 4 is set to 0.5 to 2.5mm. The rate of the height difference between the projection shaped gabled part 3 and the recessed shaped groove part 4 is set to 0.02 to 0.25, and the pitch of the projection shaped gabled part 3 or the recessed shaped groove part 4 is set to 5 to 20mm, and its condition is continued repeatedly, and then the FRP-made lock bolt 1 is hardened.
HANEUMA TORU
TANAKA YUICHI
SUZUKI KATSUHIRO
KAMIKAWA YOSHIAKI
ARISAWA SEISAKUSHO KK
CENTRAL GLASS CO LTD