| 摘要 |
PROBLEM TO BE SOLVED: To provide a grating made of synthetic resin that is always likely to be kept clean by providing a phase difference between the upper face position of the cross girder and the upper face position of the stringer and making use of the condition that there is a larger possibility trashes adhered to the grids crop up to the surface between the higher girders and the lower girders, thus making it easy to pick them up to remove. SOLUTION: In this invention, a sheet-metal cross girder 2 arranged with a reciprocal distance placed in between and a sheet-metal stringer 3 arranged with a reciprocal distance placed in between are integrally molded by synthetic resin. Then, between the top face position of the cross girder and that of the stringer, a phase difference t is provided.
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