| 摘要 |
748,111. Casings and enclosures for resistance elements. ERIE RESISTOR CORPORATION. March 5, 1954 [March 25, 1953], No. 6538/54. Class 37. [Also in Group V] A resistance element with connecting leads is sandwiched between plastic sheets and the latter are joined together by a moulding process. In the example of Figs. 1-2 the plastic casing 1 formed by moulding together plastic sheets 7, 8 encloses resistance strip 5 and transverse connecting leads 2, 3. In a second embodiment, Figs. 4-5, the leads 9, 10 are lengthwise the resistance strip 5. The plastic sheets 7, 8 may consist of felt-like paper fibres impregnated with uncured or partially cured phenolic resin. The resistance strip 5 is shown to be a carbon/plastic or other resistance film or coating 5 (liquid or powder) on a fibrous tape 4 but may comprise a self-supporting carbon/plastic composition strip. The resistance film 5 is overcoated with terminal layers 6 of conductive paste (e.g. metallic particles in resin binder) and the connecting leads where they contact the terminal layers 6 are coated with " Aquadag " (Registered Trade Mark) or similar colloidal graphite composition. The plastic casing 1 has projections, as e.g. at 9a, 10a in Fig. 4, above and below the connecting leads so as to minimize distortion of the resistance strip during moulding. The invention is directed towards quantity production of both Figs. 1-2 and Figs. 4-5 resistors by conveyer technique. The resistor of Figs. 1-2 is manufactured (see Figs. 8-6) by using as conveyer spaced wires 11, 12 which are subsequently to form the leads 2, 3. At spaced intervals the resistance strip with registering plastic sheets 7, 8 are brought into contact with each other and the wires and are cured between hinged mould sections 13, Fig. 8, which are pressed together by rolls 14. Before the wires 11, 12 are cut to form the leads 2, 3 the plastic casings may be passed over colour coating rolls 15. The resistor of Figs. 4-5 is manufactured (see Figs. 9-11) by using as conveyer plastic impregnated paper 18 unwinding from roll 17 and travelling below plastic impregnated paper 19 unwinding from roll 16. The resistance strips &c. are spaced along the paper 18 and the latter is joined to paper 19 by hinged mould sections 20, Fig. 11. After colour coating the moulded strip is cut into individual resistors. The connecting leads may have links, Fig. 12, or hooks, Fig. 13, in contact with terminal coatings 6. |
