Powder feeding apparatus

Claim 1

A powder feeding apparatus comprising a holding hopper for holding a powdery material, a metering hopper for metering the powdery material supplied from the holding hopper, a weight measuring means for measuring the weight of the powdery material in the metering hopper, an opening and closing means adapted to be selectively held at an opening position at which it opens a discharge opening in the metering hopper and a closing position at which it closes the discharge opening and a control means for controlling the actuation of the opening and closing means, the control means having a timer means for timing a discharge interval and a discharge interval setting means for setting the discharge interval of the powdery material; wherein the control means further includes a discharge interval correcting means for correcting a standard discharge interval set by the discharge interval setting means, said discharge interval correcting means comparing a standard discharge weight of the powdery material supplied every time the opening and closing means opens the discharge opening of the metering hopper with the weight of the powdery material actually discharged from the metering hopper; and, when the weight of the powdery material actually discharged from the metering hopper is larger than the standard discharge weight, said correcting means corrects the discharge interval so that it becomes longer than the standard discharge interval; and, when the weight of the powdery material actually discharged from the metering hopper is smaller than the standard discharge weight, said correcting means corrects the discharge interval so that it becomes shorter than the standard discharge interval.