| 摘要 |
PURPOSE:To prevent the looseness between the outer/inner shafts of a freely expansible/contractible shaft by forming a synthetic resin layer by means of filling the synthetic resin between these two shafts and by fixing this layer on the surface of either one of the two shafts. CONSTITUTION:A synthetic resin layer 23 is fixed on the outer surface of an inner shaft 21 of a freely expansible/contractible shaft 20. The synthetic resin layer 23 is formed as follows: with the inner shaft 21 inserted in an outer shaft 22, a synthetic resin is filled between the inner surface of the outer shaft 22 and the outer surface of the inner shaft 21, and then this synthetic resin is hardened. Through the contraction of the synthetic resin at the time of hardening, the layer 23 is separated from the inner surface of the outer shaft 22, and on the other hand ring grooves 21a, 21b, 21c on the outer surface of the inner shaft 21 and the layer 23 are firmly sticked together, and the layer 23 is made into one body with the inner shaft 21 and firmly fixed to it; thus its relative movement to both shafts 21, 22 is made smoothly. |
