Title: Process control apparatus for controlling a particleboard manufacturing system

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Abstract: An improved particleboard manufacturing system wherein the weight of each mat for forming a particleboard is continuously monitored and controlled by a process controller as the mats are formed on a moving conveyor. The actual weight of each mat is determined and utilized by the process controller to selectively control the speed of the conveyor and the rate at which wood particles are deposited by a series of formers that are located along the conveyor system to thereby control the weight of mats currently being produced. The process controller includes a control system for continuously controlling mat weight by supplying former speed control signals that are related to a predicted weight error signal, developed within the control system, and a measured weight error signal equal to the difference between a desired or target weight and the actual weight of each mat. A signal, equal to the difference between the measured error and the predicted error, is conditioned by a transfer function unit to supply a signal suitable for driving each former of the particle board manufacturing system. To provide a near optimal control system, the signal conditioning supplied by the transfer function unit is adaptively tuned on the basis of the measured weight error. A second control system is included in the process controller to provide automatic mat weight control whenever the system operator changes the production rate by altering the speed of the conveyor system. During such changes in production rate, this control system modifies the former speed based on changes in conveyor speed. A third control system, contained within the process controller, permits the controlled particleboard manufacturing system to be efficiently changed from the production of one grade of particleboard to another grade while minimizing the number of unacceptable mats that are produced. The process controller also includes a fourth control system that allows the controlled particleboard manufacturing system to be reactivated after a brief interruption in production without producing a large number of mats of an unacceptable weight.


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