FORMING METHOD FOR CROSS SECTIONAL ROLL HAVING KEY-SHAPED STEP PART AT TRAPEZOIDAL CREST SLOPE PART

摘要

PURPOSE:To form the cross section roll having key-shaped step part at the right and left of the crest with good accuracy by forming the right and left triangular projecting parts at the position becoming a key-shaped step part and by performing the forming of the key-shaped step part and forming of a trapezoidal crest after inclining the right angles side of the triangular projecting part. CONSTITUTION:A triangular projecting part 10 is formed by the upper and lower horizontal roll 11, 12 at the forming position of the key-shaped step part 3 of a steel plate. Then the right angle side of the triangular projecting part 10 is inclined by using the lower horizontal roll 15 and the key-shaped step part 3 is then formed at the bend angle larger than the bend angle at the final bending point by using the horizontal flat roll 16, 17. Thereafter, a trapezoidal crest 1 is formed so that this key-shaped step part 3 comes to the oblique side part. In this way, the cross sectional plate having key-shaped step part on the oblique side part of the trapezoidal crest 1 can be formed with rolling in good dimensional accuracy. This method may be applied for forming a deckplate, etc.