| 摘要 |
FIELD: commercial fishery; equipment of bottom trawls; bobbins for central section of footrope of trawl in rolling mode. SUBSTANCE: bobbin is made in form of body inscribed in shorter cylinder with axial hole; bobbin is made from material whose density is close to density of water (rubber for example). Body of bobbin consists of rim, disk, hub and stiffeners. Center plane of disk coincides with center planes of rim and hub; it is plane of symmetry of bobbin; length of rim is equal to length of hub (length of bobbin). Rim and hub are strengthened with 5 to 9 stiffeners on either side from disk which are evenly distributed over circle; their heights are equal to half difference between length of bobbin and thickness of disk, other sizes being equal. Inner contours of rim and outer contours of hub in axial sections of bobbin, as well as lateral contours of cross sections of stiffeners have slopes of 10 to 30 deg; thicknesses of members increase in direction from end planes to plane of symmetry of bobbin; joints of edges of chambers formed between rim, disk, hub and stiffeners are rounded off; sizes of main components of bobbin are within the following limits: length, 0.2 to 0.4 D; disk thickness, 0.5 to 0.1 D; thicknesses of rim and hub measured at end planes, 0.04 to 0.08 D; thicknesses of stiffeners measured in end planes, 0.01 to 0.02 D; rounding-off radii in end planes, 0.04 to 0.2 D and in longitudinal and transverse sections, 0.02 to 0.05 D, where D is diameter of bobbin. EFFECT: reduced mass; reduced labour consumption; low cost. |
