Accurate dosing of flowable solids or liquids - with computer correction of weighing errors, esp. when preparing mixts. for concrete or asphalt

摘要

Shortly before reaching the desired value(S) of each dose, the feeding appts. is stopped at an actual wt. (Z) less than wt.(S). During the feeding pause, the measuring error(N) is determind, and then feeding is re-commenced, but is switched off at a point S - N to allow for the error(N) so an accurate dosed wt. (S) is obtd. In the pref. process, error(N) is calculated by a computer and used to produce a signal which switches off the feeder before point(S) is reached. The values(N) may also be stored in a memory device and used to correct each dose of material employed to make a mixt. or fill a container. The feeding rate may be reduced during the second phase, i.e. when adding wt. (S - Z); and Z is pref. 85-95% S. Used esp. in the prepn. of mixts., e.g. for asphalt or concrete; filling sacks with solids; or filling containers with liqs.