| 摘要 |
A supporting frame for an expandable boom with a liquid-tight sleeve forming a floating body and being arranged to be stretched out by means of jointed supporting frames which in their expanded state take on an approximate rectangular or square form, subjected to a spring force. The supporting frame 3 consists of a continuous rail 8 of injection-moulded plastic with good elastic bending properties. The rail contains closed channels 15 along the sides of the frame and corner portions deformed into elastic joints. Glass-fibre rods rigid against bending are inserted into these channels between the joints. Through the usage of adequately tough plastic material, the frame is given necessary elasticity and strength in the joints, while the rods 16 inserted into the channels give necessary rigidity to the boom. The elastic joints are particularly adequate for absorbing varying loads, which tend to warp the frame during the use of the boom. The embodiment allows for rational, automated manufacture of supporting frames, which form parts of expandable booms in large quantities. <IMAGE> |
