| 摘要 |
It is described a tensioning frame (7; 10; 12.1) for an elastic membrane or similar element (3; 11; 13) that includes: - a first means (8, 7.1, 7.5; 10.1, 10.2; 12.2) conceived to tighten said elastic membrane or similar element (3; 11; 13) along a first continuous closed line (3.2; 10.4, 13.1), on said tensioning frame (7; 10; 12.1), to ensure that every relative movement is prevented between said first continuous closed line (3.2; 10.4, 13.1) of said membrane (3; 11; 13) and said tensioning frame (7; 10; 12.1), - a second means (7.8, 7.3; 7.12, 7.8, 7.3; 7.12) conceived to press against said elastic membrane or similar element (3; 11; 13) along a second continuous closed line, inside said first continuous closed line (3.2; 10.4, 13.1), to permit a relative movement between said membrane (3; 11; 13) and said tensioning frame (7; 10; 12.1); - a third means composed of a fluid under pressure enclosed in a . hermetic chamber (7.10; 7.12) conceived to push said second means (7.8, 7.3; 7.12, 7.8, 7.3; 7.12) against said elastic membrane or similar element (3; 11; 13) with a force that is varied according to said pressure whose level, in turn, is adjustable using means common to prior art. |
