| 摘要 |
According to the invention, for cutting a valve hole and roughening the surrounding surface of an inner tube in a single operation, use is made of a roughening and cutting apparatus having a circular roughening disc (9) which can be lowered onto the flat tube (4) lying in a holder (1) and bears in its centre a downwardly protruding cutting attachment (11) of a height corresponding to the thickness of a tube wall (5), for cutting the valve hole (12). <IMAGE> |
