| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a marking device which can evenly and distinctly draw a line over the entire length of the inner surface of a steel pipe with a simple structure. <P>SOLUTION: The invented marking device includes a marking jig 2 and a towing tool (bar 3). The marking jig 2 includes a cylindrical body 4 formed by notching a part of a circular cylinder having an outer diameter which is smaller than the inner diameter of the steel pipe 1 and is equal to or larger than the inner diameter of the steel pipe 1 minus 1 mm. The cylindrical body 4 is made to retain a bold-faced or ultra-bold-faced felt-tipped oil-based pen 5 so that the tip of the pen 5 protrudes by 2 mm±1 mm outward from the outer periphery of the cylindrical body 4. The towing tool (bar 3) has a length larger than the entire length of the steel pipe 1 and tows the marking jig 2 while the outer surface of the marking jig 2 and the inner surface of the steel pipe 1 slide therebetween. <P>COPYRIGHT: (C)2013,JPO&INPIT |
