Method and appparatus for monitoring and controlling thermoplastic extruder output
AssigneeLuwa AG
InventorDana G. Darley
Life of this patent
Estimating the term…
Abstract
In a gear pump assisted thermoplastic extrusion system, the speed of operation of the gear pump is adjusted in relation to fluctuations in both the rate of product output from the system and the rate of material input to the system to precisely maintain a desired weight per unit length of the extruded product within close tolerances.
Claims18
In a method of extruding thermoplastic material comprising passing said material successively through an extruder, a variable speed rotary gear pump, a die, and a variable speed driven output device, the improvement comprising controlling the speed of operation of at least one of said gear pump and said driven output device by at least periodically determining a value representing material output volume from said output device, at least periodically determining a value representing material input density to said extruder, adjusting the speed of operation of said gear pump to compensate for fluctuations in the determined output value, and adjusting the speed of operation of one of said gear pump and said output device to compensate for fluctuations in the determined input value.
In an apparatus for extruding thermoplastic material comprising an extruder, a variable speed rotary gear pump, a die, and a variable speed driven output device arranged for material passage successively therethrough, the improvement comprising means for controlling the speed of operation of at least one of said gear pump and said output device, said controlling means including means for at least periodically determining a value representing material output volume from said output device, means for at least periodically determining a value representing material input density to said extruder, first means for adjusting the speed of operation of said gear pump to compensate for fluctuations in the determined output value, and second means for adjusting the speed of operation of one of said gear pump and said output device to compensate for fluctuations in the determined input value.
Dependencies are inferred from the claim text.