Manufacture of abrasion-resistant screening apparatus

摘要

Manufacture of a perforate screening member having a structurally strong substrate supporting a layer or coating of abrasion-resistant elastomer, the elastomer having perforations coincidental with perforations in the substrate, the perforations in the elastomer in some cases being smaller in cross sectional area than the perforations in the substrate and in some cases having sidewalls which taper downwardly and outwardly, by forming a layer or coating of flowable, hardenable elastomer on the upper surface of the substrate while the substrate has its perforations blocked by forms which project through the layer of elastomer, the upper section of the form in some cases being of smaller diameter throughout the thickness of the layer of elastomer than the diameter of the substrate perforation and in some cases tapering upwardly and inwardly. An elastomer treatable by heat and pressure, such as crude rubber, can form the abrasion-resistant layer or coating on the substrate and can be treated, as by vulcanization, in the same mold. Where the substrate is formed of a castable material, the same mold can be used to cast the substrate as is used to form the elastomer coating on the substrate after the latter has hardened.