| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a jack base whose cut surface is simplified, the cut surface being formed on a screw stock in order to avoid interference with a projection of a support member. Ž<P>SOLUTION: The jack base 11 is for use in supporting the support member for constructing temporary scaffolding, on the ground surface, and has: the base plate 12; the screw stock 13 which is erected from an upper surface of the base plate 12, allows a lower portion of the support member to be fitted therein, and has a male thread portion 16 formed on the periphery thereof; and a handle 14 which is arranged on the periphery of the screw stock 13, and movable along an axial direction of the screw stock 13 according to a contrapositive relationship between the male thread portion 16 and a female thread portion 20. To manufacture the screw stock 13, after formation of the male thread portion 16 on the periphery of a metallic pipe member, two locations of the periphery, that are 180-degree opposed to each other, are simultaneously pressed linearly along the axial direction of the screw stock 13, and therefore the screw stock 13 is deformed like a line-symmetrical ellipse in which pressed areas are most close to each other. Further the deformation does not effect predetermined areas in a major axis direction orthogonal to a minor axis direction connecting between both the pressed locations. Ž<P>COPYRIGHT: (C)2010,JPO&INPIT Ž
|
