Method and apparatus for controlling the thickness of extruded stock

Claim 2

In a process comprising an extruder for providing a continuous sheet length of elastomeric extrusion, a variable speed take-away conveyor belt to vary the thickness of the extrusion as it exits the extruder, a running-weigh-scale to measure the weight per unit area of the continuous extrusion, a cooling train to set the extrusion, a skiver to cut the continuous extrusion into specific lengths, and a check-weigh-scale to measure the cut length weight, a method of controlling the thickness of the cut lengths of extruded elastomer comprising the steps of: A. sampling the weight of the extrusion at the running-weigh-scale each second; B. computing and storing one-minute averages of the running-weigh-scale samples; C. sampling the weight of the cut lengths of extrusion at the check-weigh-scale; D. comparing the check-weigh-scale value to the oldest stored running-weigh-scale one-minute average to obtain a targeted running-weigh-scale average; E. comparing the targeted running-weigh-scale average to the newest stored running-weigh-scale one-minute average to obtain a deviation from the targeted value if one exists; and F. converting the deviation from the targeted running-weigh-scale value to a control signal for increasing or decreasing the speed of the take-away belt to vary the thickness of the extrusion in accordance with the amount of deviation and the take-away speed of the belt.

Claim 3

The method as set forth in claim 1 wherein the running-weigh-scale one-minute averages are stored in a series sequence of "A" through "n" registers with the "A" register accepting the newest computed one-minute average while the "n" register stores the oldest one-minute average, the number of "n" registers equal to the amount of time it takes the extrusion to pass from the running-weigh-scale to the check-weigh-scale.

Claim 4

In a process comprising an extruder for providing a continuous sheet length of elastomeric extrusion, a variable speed take-away belt to vary the thickness of the extrusion as it exits the extruder, a running-weigh-scale to measure the weight-per-unit-area of the continuous extrusion, a cooling train to set the extruded material, a skiver to cut the continuous extrusion into specific lengths, and a check-weigh-scale to measure the cut length weight, apparatus for controlling the thickness of the cut lengths of extruded elastomer comprising: A. means to sample the weight of extrusion passing over the running-weigh-scale each second; B. means to compute one-minute averages of of the running-weigh-scale samples; C. means to store the one-minute running-weight-scale averages; D. means to sample the weight of the cut lengths of extrusion at the check-weigh-scale; E. first comparator means to compare the check-weigh-scale samples to the oldest stored running-weigh-scale one-minute averages to obtain a targeted running-weight-scale average; F. second comparator means to compare the targeted running-weigh-scale average to the newest stored running-weigh-scale one-minute average to obtain a deviation from the targeted value if one exists; and G. converting means to convert the deviation from the targeted running-weigh-scale value to a control signal for increasing or decreasing the speed of the take-away belt to vary the thickness of the extrusion in accordance with the amount of deviation and the take-away speed of the belt.

Claim 5

In a process comprising an extruder for providing a continuous sheet length of elastomeric extrusion, a variable speed take-away belt to vary the thickness of the extrusion as it exits the extruder, a running-weigh-scale to measure the weight-per-unit-area of the continuous extrusion, a cooling train to set the extruded material, a skiver to cut the continuous extrusion into specific lengths, and a check-weigh-scale to measure the cut length weight, apparatus for controlling the thickness of the cut lengths of extruded elastomer comprising: A. means to sample the weight of extrusion passing over the running-weigh-scale each second; B. means to compute one-minute averages of of the running-weigh-scale samples; C. means to store the one-minute running-weight-scale averages; D. means to sample the weight of the cut lengths of extrusion at the check-weigh-scale; E. first comparator means to compare the check-weigh-scale samples to the oldest stored running-weigh-scale one-minute averages to obtain a targeted running-weight-scale average; F. second comparator means to compare the targeted running-weigh-scale average to the newest stored running-weigh-scale one-minute average to obtain a deviation from the targeted value if one exists; and G. converting means to convert the deviation from the targeted running-weigh-scale value to a control signal for increasing or decreasing the speed of the take-away belt to vary the thickness of the extrusion in accordance with the amount of deviation and the take-away speed of the belt.

Claim 6

The apparatus as set forth in claim 3 wherein the means to store comprises a series sequence of "A" through "n" registers, the "A" register accepting the newest computed running-weigh-scale one-minute average while the "n" register stores the oldest computed one-minute average, the number of "n" registers being equal to the time it takes the extrusion to pass from the running-weigh-scale to the check-weigh-scale.