| 摘要 |
<p>1,250,784. Making profiled sections; punches. G. LANG. 29 Oct., 1968 [30 Oct., 1967], No. 51306/68. Headings B3A and B3W. A method of forming from strip metal a profiled section having perforations spaced at predetermined longitudinal intervals comprises perforating the strip in the flat state at longitudinal intervals less than the predetermined final spacing to allow for longitudinal stretch during bending of the strip to form the profiled section. The thicker the strip metal used, the smaller are the initial intervals relative to the predetermined final intervals. A strip to be subsequently formed into a channel section may be perforated in a punch press, Fig. 1, having rows of punches and dies 5 spaced by intervals TR, press guides 9 and strip guides 10, 11, the feed stroke HR being twice the pitch TR. Reference TB indicates the interval between the holes which will be in the base and the limbs of the channel respectively and T the interval between the holes in the base in the transverse direction, the longitudinal distance between the holes after bending of the strip to channel section being equal to distance T. In another form of press the longitudinal pitch of the punches and dies may be varied mechanically or hydraulically using wedges and holes at intervals TR are produced by having the punch pitch 3TR and the feed stroke 2TR. Edge guides may be adjustable transversely of the strip to locate narrower strips to be formed subsequently into L sections.</p> |
