| 摘要 |
<p>A method of forming the end of a flat metal tube (10) includes mechanically forming a corner region (10a, 10b) of the flat metal tube, by forming the corner with an impressing tool (21) having a corner forming workface so that the corner is thereby given a shape corresponding to all or part of the workface. The method of forming the corner region includes initiating a seam by folding together, or partially folding together, the cut edges of the flat metal tube and forming a curved vee-shape which is located centrally about a plane parallel to the flat sides of the tube and with the apex of the vee-shape towards the adjacent tube corner by using a lead-in surface (22) on the impressing tool (20) which blends with the corner forming workface and which comprises a centre line (24) which describes an angle (25) greater than 20 DEG as measured against the width of the flat tube to be formed. All or part of the remaining tube end is closed and sealed by subsequent operations. The invention includes apparatus for carrying out the method and also provides a flat metal tube having at least one formed corner of a rounded shape.</p> |
