| 摘要 |
A method of effecting practical, simple and economical production of ore-concentrating pads of numerous configurations and sizes. Nails are employed to secure extruded strips to a backing sheet and an underlying support, following which the strips are pivoted about the nails and progressively secured to the backing sheet. The nails are then removed and the resulting pad is vacuum-applied to a concave bowl and adhesively secured therein. The shapes and positions of the strips are such that there is very close sealing engagement between adjacent strips, after the pad is made into bowl shape, yet there is great elasticity permitting practical vacuum application to the bowl. In one embodiment, the strip-formed pad is used as a mold over which plaster of paris is molded, and the plaster of paris is used as a guide for a tracing machine adapted to make a mold for the mass-manufacture of large numbers of concentrating pads. |
