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US 4,543,891 AGranted
Apparatus and process for heat treatment
AssigneeWestinghouse Electric Corp.
InventorsWilliam T. O'Sullivan, Earl C. Pace
Life of this patent
Estimating the term…
Abstract
Apparatus and process is disclosed for heat treating of material in a furnace comprising a fan driven by an electric motor, a load sensor which senses the motor load and a speed controller responsive to the load sensor signal for controlling the speed of the electric motor.
Claims3
Apparatus for batch-annealing a charge comprising:
- (a) a batch-annealing furnace;
- (b) a fan for circulating hot gas within said furnace;
- (c) an electric motor on which a load is exerted by said fan;
- (d) a load transducer for detecting an electrical load on said motor and capable of generating a load signal;
- (e) a load change detector responsive to said load signal and capable of generating a load change signal;
- (f) a frequency reference integrator responsive to said load change signal and capable of generating, storing and changing a reference signal responsive to said load change signal;
- and
- (g) an adjustable frequency drive responsive to said reference signal and capable of supplying a varying frequency alternating current power to said motor.
5 more elements
A process of batch-annealing a charge comprising the steps of:
- (a) increasing the temperature of a heat transfer gas within a batch-annealing furnace during heat-up of said charge;
- (b) circulating said heat transfer gas within said batch-annealing furnace with a fan driven by an electric motor;
- (c) sensing a change in the electrical load on said motor in response to a change in density of said heat transfer gas and generating a signal related thereto;
- (d) increasing the speed of said motor responsive to said signal to increase gas circulation within said furnace as the density of said gas decreases;
- (e) decreasing the temperature of said heat transfer gas within said furnace during cool-down of said charge;
- and
- (f) decreasing the speed of said motor responsive to said signal to decrease gas circulation within said furnace as the density of said gas increases.
4 more elements
A method for significantly reducing the processing time in a batch-annealing furnace comprising the steps of:
- (a) circulating a heat transfer gas within said furnace with a fan driven by an electric motor;
- (b) sensing the electrical load on said motor and generating a signal related to said load;
- (c) increasing the speed of said motor in response to a change in said signal to maintain a substantially constant load thereon as said gas is heated and the density thereof decreases;
- and
- (d) decreasing the speed of said motor in response to a change in said signal to maintain said load substantially constant as said gas is cooled and the density thereof increases.
2 more elements
Dependencies are inferred from the claim text.