| 摘要 |
<p>PROBLEM TO BE SOLVED: To realize an automatic production system capable of dealing with changes in an inclined angle such as stairs by using projection welding, in the production method of a beam structure like a metallic handrail. SOLUTION: The manufacture is such that a number of bar-like short vertical material 3 are arranged at proper spaces apart between a pair of horizontal materials and that the upper and lower ends of each vertical material so arranged are joined to the mutually opposing faces of the horizontal materials. In this case, the preliminarily continuous bar-like vertical material is pressed at proper spaces apart to form a flat projection 7, which, flattened by press working, is cut to form a vertical material of a normal dimension. Then, the vertical material so cut off and the horizontal material are held by an electrode clamp; after the upper end of the vertical material and the projection of the lower end are pressed against the faces mutually in contact of the horizontal material, projection welding is performed by imparting through the electrode clamp a pressing force and a welding current necessary for the welding. In addition, with a press angle and a cutting angle set in accordance with the inclination of the stairs, the edge preparation is carried out on the projections at the upper and lower ends of the vertical material.</p> |
