| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a method for forming a duct by which pipes which are opened from the respective walls of adjacent hand-holes so as to face each other and have an offset between respective pipe axes can be connected to each other without the necessity of special technical skill and without applying an unnatural stress, etc., to piping, the piping free from strain can be realized and the duct in which a cable or a wire is not caught when it is drawn thereinto can be formed. SOLUTION: One end of a cylindrical short straight pipe is used as a pipe insertion opening. An annular elastic unit with a wedge-shaped cross-section is attached to the outer circumferential surface so as to have its diameter gradually reduced toward the pipe end. A conical cylindrical unit is attached so as to have its conical surface whose inner surface has a conical unit which follows the outer surface slope of the annular elastic unit with three wedge-shaped surfaces and whose small diameter part is further contracted, and then expanded into a trumpet shaped flange part brought into contact with the outer circumferential surface of the annular elastic unit. The minimum inner diameter of the contracted diameter part of the conical cylindrical unit is not larger than a value obtained by deducting the thickness of the short straight pipe from the outer diameter of the short straight pipe.</p> |
