| 摘要 |
<p>The aurning, with a hinged arm mounting, has a canvas which can be wound up and unwound by means of a spindle, and spring stretched by means of a hinge joint comprising hinged arms. Where these arms (1, 2) are joined together by inside hinge joints (5) there are helical springs (12) encompassing the hinge axes. An additional torsional moment may be provided by helical springs on the outside hinge joints. The springs on adjacent hinge joints may have opposing vectors. The helical springs are coiled strips of sheet metal. Optimal canvas stretching is achieved without any unpleasant effect on the aurnings appearance.</p> |
