| 摘要 |
PURPOSE:To give a tension to a hoop without contact with the hoop upper face by feeding a pressurized air to the opening part of an air pressure chamber abutting a hoop receiving face provided on a machine frame and forming an exhaust gap for passing the hoop between the outer peripheral edge and receiving face of said opening part. CONSTITUTION:The hoop receiving face 2 composed of a felt is provided on the upper face of a machine frame 1 and the air pressure chamber 3 formed by the outer peripheral edge 4 having a rectangular plate 9, side frame 10 and endless o ring is provided so as to abut the hoop receiving face 2. An air is press-fitted via an air pressure pipe 12 and air pressure hole 11 to said air pressure chamber 3. With this air pressure the lower face of the hoop 5 is press-welded to said hoop receiving face 2. Said rectangular plate 9 is pushed up against the pressing force of a spring 10 by the air pressure and the exhaust gap 6 for passing the hoop 5 is formed between said outer peripheral edge 4 and hoop receiving face 2. The necessary work is performed by giving a tension to the hoop 5 with no effect on the hoop 5 upper face by tracting the hoop 5 in this state.
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