| 摘要 |
<p>1489838 Forming elastomeric screens T C ADAMS 14 April 1976 [15 April 1975] 15485/75 Headings B1D and B2H An elastomeric, e.g. polyurethane, screen or screen liner for a grading or dewatering apparatus is formed by (i) placing face to face two sheets 3, 5 of elastomeric material, at least one of which is to form the screen or screen liner; (ii) punching apertures 6 through both sheets; and (iii) separating the sheets to form at least one screen or screen liner sheet having apertures which taper from one face to the other. Two screens may be formed by punching through identical sheets as shown in Figure 3. Alternatively, the backing sheet may be waste material or material of different elastic properties, hardness and/or thickness. A further backing sheet may be applied to the top face of the screen-forming sheet before punching. The apertures may be formed in more than one punching stage. The elastomeric sheet material may contain openwork reinforcing elements. By use of a relatively thin backing sheet, the apertures in the screen may be formed to have an angle of taper of substantially zero at their narrow end. The screens or screen liners may be used in grading apparatus, e.g. for grading sand or gravel, or dewatering apparatus, e.g. for dewatering coal slurries. In either case the screen may be inclined and/or oscillated. The screen may be flat or curved and may form part of a screen centrifuge.</p> |
