| 摘要 |
An improved structure for a chest-type surfboard (bodyboard) comprises a plurality of elongate members (3) extruded from expanded polyethylene structural foam. The members (3) are then joined laterally to one another by means of a thermal fusion bonding process which compacts the expanded polyethylene, thus forming, at the laterally adjoining walls of the members (3), a corresponding number of rigid films (4) oriented at right angles to bending stress applied to an upper or a lower surface of the joined members (3), thus acting as girders having their greater direction of strength opposing the bending stress. A thermally laminated skin (2) is disposed on both upper and lower surfaces of the joined members (3), forming a "sandwich" assembly which is subsequently subjected to complementary operations of coating the top, the bottom, and the side edges, as well as surface finishing and the other customary operations. The "sandwich" assembly shows improved rigidity and elasticity with no increase of weight over conventional chest-type boards because the density of the foam forming the elongate members (3) is about 20 Kg/m<3>, less than in conventional boards, while the density of the foam forming the skins (2) is about 140 Kg/m<3>, much greater than that of conventional boards. The average density is, thus, in the region of conventional boards (36-42 Kg/m<3>). |
