GB1248568A - Edge sensing means - Google Patents

Abstract

1248568 Guiding webs; endless conveyers HINDLE SON & CO Ltd 28 Nov 1968 [30 Nov 1967] 54464/67 Headings G3P P12B P11 and P1G [Also in Division D2] Automatic guiding apparatus for a travelling web, e.g. an endless papermakers felt, includes a guide roll over which the web passes, a slewing mechanism for slewing the roll to corrent lateral wanderings of the web from a normal running track, and sensing means comprising a timer associated with two nozzle outlets from which jets of fluid, e.g. compressed air or water, can issue to sense the presence or absence of the web. As shown, the sensing means comprises a U-shaped bracket 34 carrying on one limb two nozzles 38 and on the opposite limb associated detectors in the form of pitot tubes 36, each detector sensing the jet issuing from the respective nozzle 38 when the jet is not interrupted by the intervening web 10. Each tube 36 is connected to a pressureactuated switch or valve which is employed to actuate the slewing mechanism. In another embodiment Fig. 4, (not shown) each detector consists of a cup, on which the jet impinges when not interrupted, secured to the outer end of a spring-counterbalanced hinged lever which is arranged to operate a micro-switch to control the slewing mechanism. To economize on fluid consumption the jets may be operated intermittently e.g. 5 seconds on and 25 seconds off, so long as the web continues to run on its normal track, this intermittent operation being superseded by continuous operation when corrective guiding action is initiated; suitable timing arrangements for this purpose are described with reference to Figs. 6 to 8 (not shown). The guide roller and associated slewing mechanism Figs. 1 to 3, (not shown) may be of the type described in Specification 899001.