| 摘要 |
649,690. Seaming non-metallic sheet material. SINGER MANUFACTURING CO. Oct. 13, 1948, No. 26638. Convention date, July 3. [Class 42 (i)] An electronic seaming machine for dielectric sheet material comprises a work support, means including an electrode movable toward and from the work support for establishing a very high-frequency electric field, a work thickness detecting member disposed for engagement with work in the region of said field, relatively movable members co-operating with one another to limit the movement of the electrode toward the work support, one of which members is variably positioned by the detecting member so that the said electrode movement is limited in accordance with variations in the thickness of the work, and adjustable means for modifying the effective action of said relatively movable members. As shown, in a machine modified from that described in Specification 603,412, the electrode bar 48 carrying the upper electrode 80, Fig. 2, is pressed downwardly by a spring 49 and is reciprocated by an eccentric 77, Fig. 3, on a main shaft 15, engaging a roller 59 mounted on a bracket 57 carried by a nut 55 adjustably secured to the top of bar 48. The downward movement of electrode bar 48 is limited by engagement of a nose or cam arm 95 on bracket 57 with an arm 94 of a bell-crank lever 88; the position of arm 94 is varied automatically according to the thickness of the work by engagement of the other arm 87 of lever 88 with an extension 86 on the presser bar 41 carrying the upper feed roller 43. Lever 88 is pivoted in a block 91 adjustably secured to the machine frame by a screw 92 and slot 93. Prior to commencing seaming, block 91 and nut 55 are adjusted to give the desired minimum spacing of the electrodes, and the desired dwell of the upper electrode in its lowest position, for the thinnest material to be treated. |
