Steel plate hole center detection jig

Abstract

This jig is used to accurately detect the center positions of bolt holes in steel sections and thick plates used in civil engineering and architectural columns, beams, foundation piles, etc. During the construction of a structure, it is mandatory to accurately measure and record the center-to-center dimensions of multiple bolt holes in the steel sections and thick plates used as materials, as well as the dimensions between the center and the edge of the material, in order to ensure the structure's strength. This jig is an auxiliary tool for accurately detecting the center positions of round holes for such measurements. As shown in the "Reference Diagram of Components," it consists of three parts: the jig body, a hex bolt, and a washer. The jig body is shaped as shown in the figure, consisting of a semi-cylindrical section, a cylindrical section, and a conical section, with a bolt hole formed from the tip of the conical section toward the center of the cylindrical section for threading a hex bolt. To detect the center position of a round hole in a thick steel plate, as shown in the "Reference Diagram Showing the Usage State," the conical portion of the jig body is inserted into the round hole from one side of the steel plate. Next, a hex bolt with a washer is inserted from the other side and inserted into the bolt hole in the conical portion of the jig to tighten the steel plate. When tightened, the conical portion causes the center axis of the cylindrical portion to coincide with the center of the hole in the steel plate, and the center axis position is accurately determined to be the hole center position. There is a step between the cylindrical portion and the semi-cylindrical portion of the jig body. As shown in the plan view, a narrow slit is provided on the top surface of the semi-cylindrical portion, extending perpendicularly from the center axis of the cylindrical portion. The step is provided for convenience when using a square to measure the distance between other hole centers, the ends of steel sections, etc.

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