| 摘要 |
<p>A method of constructing a frame for a filtering screen from a polymer material is described in which a wire frame reinforcement is wholly encapsulated during the frame moulding process so that two parallel spaced apart wires extend through each of the intersecting orthogonal ribs which define the open area of the frame across which the wirecloths are stretched. The wire frame is formed from ordinary mild steel and is separated from the stainless steel woven wirecloth by a sufficient thickness of polymer plastics material to prevent corrosion or electrolytic action. The rigidity of the frame is enhanced by the two parallel reinforcing wires which extend through each of the orthogonal ribs, one near the upper and the other near the lower edge of each rib, so as to form a beam-like assembly. The surfaces of the frame in which the wirecloths are embedded are formed with ridges and the crests of the latter extend to different heights. The crests are softened by heating during the manufacturing process and the wirecloths stretched over the frame are forced into the softened crests after which the assembly is allowed to cool and cure. By tensioning the wires in the wirecloth before they become embedded in the polymer frame, the desired tensions, possibly different in different layers of wirecloth, can be obtained and maintained. The frame is reusable by stripping wirecloths from the top of the frame and fitting fresh wirecloths over the plastics material and heating the regions which are to encapsulate the fresh wirecloth. In a preferred refurbishment method the crests are reinstated by additional plastics material in a refurbishment process before fresh wirecloth is attached to the frame. By forming male and female ends to the frames, and pushing one into the other, so a sealing joint is formed between two similarly constructed frames located end to end.</p> |
