| 摘要 |
1302642 Blasting E I DU PONT DE NEMOURS & CO 19 April 1971 [26 Jan 1970] 20373/71 Heading B3D [Also in Division B5] The surface of a steel quenching roller used in casting plastics film is given a roughness exceeding 15 microinches r.m.s. (e.g. 18-28 microinches) and a multiplicity of interconnecting pits, by blasting against it particles of sand, glass, or alumina of particle size 80-320 mesh from a “ inch diameter orifice at an air pressure of 115 p.s.i. The blasted surface may be polished to obtain a roughness in the preferred range. |
