Joinery section for making e.g. opening frame of door, has steel flat sections assembled on two longitudinal lines by utilizing welding spots, which are spaced from each other to maintain empty space of five millimeter between flat sections

摘要

The section has a pair of flat sections (21, 22) assembled with each other along two longitudinal lines by utilizing welding spots (23). One flat section (21) is fixed at a center part of another flat section (22). The welding spots are regularly distributed along the length of both the flat sections and are spaced from each other at a distance of 25 to 40 millimeters to maintain an empty space (e) of 5 millimeters between the flat sections.