| 摘要 |
A method of making a supporting grid for tubes and such a grid comprising a central reticular structure formed of main (1,2) and secondary (3,4) intersecting strips. An inner annular frame is formed in the same material as that of the strips so as to tightly receive therein the ends of said strips, said inner fram being higher than the reticular structure so that lower and upper projecting portions are created together with cleaning ducts. An external annular frame of a different material and axially extending inward facing dogs are provided at the inner portion of said external frame. The inner frame (7) and the external frame are assembled such that at room temperature said dogs fit tightly to theinner cylindrical surface of said projecting portions, while play (17) existing between the external cylindrical surface of the inner frame and the external frame allows the free thermal expansion of the two materials. |
