| 摘要 |
PROBLEM TO BE SOLVED: To connect a shaped angle steel and a flat steel bar without clearances and firmly weld them to drain rainwater or condensed water and prevent rusting and freezing even if there are burrs or projections on a flat bar, by drawing the inside corner part of an angle steel in the outside R direction to form a groove. SOLUTION: The inside corner part of an angle steel is made to flow in the outside R in the state the first and second sides 1, 2 of the angle steel crossing at right angles are restricted not to longitudinally stretch, in order to make a dent and form a groove 3 at the inside corner. The groove 3 is shaped to form a square having nearly 130 degrees in respective anglesαbetween adjacent sides and reach the area (a) of the first and second sides 1, 2 at least by 1mm or longer. In this way, the inside corner part is hardened with working and the strength is increased. When a flat bar steel B is connected to the inside corner part with the groove 3, any clearance is not brought in the corner even if there are burrs or projections and further, the groove 3 serves as a beveled function to firmly weld the bar. And further, condensed water or rainwater can be drained through the groove 3 and hence, rusting and freezing in winter can be prevented.
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