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 power draw at the extruder each second; (d) computing and storing one-minute averages of the power draw samples; (e) conditioning the oldest and newest power draw one-minute averages to obtain a power draw deviation if one exists; (f) sampling the weight of the cut lengths of extrusion at the check-weigh-scale; (g) comparing the check-weigh-scale value to the oldest stored running-weigh-scale one-minute average and the power draw deviation to obtain a targeted running-weigh-scale average; (h) comparing the targeted running-weigh-scale average to the newest stored running-weigh-scale one-minute average to obtain a deviation for the targeted value if one exists; and (i) 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, and wherein said power draw one-minute averages are stored in a series sequence of "B" through "m" registers with the "B" register accepting the newest computed one-minute average while the "m" register stores the oldest one-minute average, the number of "m" registers equal to the time it takes the extrusion to pass from the extruder exit orifice to the check-weigh-scale.

Claim 4

The method as set forth in claim 2 wherein the oldest and newest power draw one-minute averages are compared and the difference between the two is conditioned by a constant "k" indicative of the characteristics of the extruded material.

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 the extrusion at the running-weigh-scale each second; (b) means to compute and store one-minute averages of the running-weigh-scale samples; (c) means to sample the power draw at the extruder each second; (d) means to compute and store one-minute averages of the power draw samples; (e) means to condition the oldest and newest stored power draw one-minute averages to a constant "k" indicative of the characteristic of the extruded material to obtain a power draw deviation if one exists; (f) means to sample the weight of the cut lengths of extrusion at the check-weigh-scale; (g) first comparator means to compare the check-weigh-scale samples to the oldest stored running-weigh-scale one-minute average and the power draw deviation to obtain a targeted running-weigh-scale average; (h) 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 (i) 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 on the belt in accordance with the amount of deviation and the take-away speed of the belt.

Claim 6

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 the extrusion at the running-weigh-scale each second; (b) means to compute and store one-minute averages of the running-weigh-scale samples; (c) means to sample the power draw at the extruder each second; (d) means to compute and store one-minute averages of the power draw samples; (e) means to condition the oldest and newest stored power draw one-minute averages to a constant "k" indicative of the characteristic of the extruded material to obtain a power draw deviation if one exists; (f) means to sample the weight of the cut lengths of extrusion at the check-weigh-scale; (g) first comparator means to compare the check-weigh-scale samples to the oldest stored running-weigh-scale one-minute average and the power draw deviation to obtain a targeted running-weigh-scale average; (h) 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 (i) 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 on the belt in accordance with the amount of deviation and the take-away speed of the belt.

Claim 7

The apparatus as set forth in claim 4 wherein the means to store running-weigh-scale one-minute averages 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, and the means to store the power draw one-minute averages comprises a series sequence of "B" through "m" registers, the "B" register accepting the newest computed power draw one-minute average while the "m" register stores the oldest one-minute average, the number of "m" registers being equal to the time it takes the extrusion to pass from the extruder exit orifice to the check-weigh-scale.

Claim 8

The apparatus as set forth in claim 5 wherein the means to condition the oldest and newest stored power draw one minute averages comprises means for computing the difference between the newest power draw average in the "B" register and the oldest power draw average in the "m" register and multiplying the difference by a constant "k" indicative of the characteristic of the material being processed in the extruder.

Claim 9

In a process comprising an extruder for providing a continuous sheet length of elastomeric extrusion, a variable speed take-away belt conveyor to vary the thickness of the extrusion as it exits the extruder, a first running-weigh-scale to measure the weight per unit area of the continuous extrusion, a cooling train to set the extrusion, and a second running-weigh-scale to measure the weight per unit area of the cooled extrusion, a method of controlling the thickness of the extruded elastomer comprising the steps of: (a) sampling the weight of the extrusion at the first running-weigh-scale each second; (b) computing and storing one-minute averages of the running-weigh-scale samples; (c) sampling the power draw at the extruder each second; (d) computing and storing one-minute averages of the power draw samples; (e) conditioning the oldest and newest power draw one-minute averages to obtain a power draw deviation if one exists; (f) sampling the weight of the extrusion at the second running-weigh-scale; (g) comparing the second running-weigh-scale sample to the oldest stored first running-weigh-scale one-minute average and the power draw deviation to obtain a targeted running-weigh-scale average; (h) comparing the targeted running-weigh-scale average to the newest stored one-minute average from the first running-weigh-scale to obtain a deviation for the targeted value if one exists; and (i) 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 extrusion thickness in accordance with the amount of deviation and the take-away speed of the belt.

Claim 10

In a process comprising an extruder for providing a continuous sheet length of elastomeric extrusion, a variable speed take-away belt conveyor to vary the thickness of the extrusion as it exits the extruder, a first running-weigh-scale to measure the weight per unit area of the continuous extrusion, a cooling train to set the extrusion, and a second running-weigh-scale to measure the weight per unit area of the cooled extrusion, a method of controlling the thickness of the extruded elastomer comprising the steps of: (a) sampling the weight of the extrusion at the first running-weigh-scale each second; (b) computing and storing one-minute averages of the running-weigh-scale samples; (c) sampling the power draw at the extruder each second; (d) computing and storing one-minute averages of the power draw samples; (e) conditioning the oldest and newest power draw one-minute averages to obtain a power draw deviation if one exists; (f) sampling the weight of the extrusion at the second running-weigh-scale; (g) comparing the second running-weigh-scale sample to the oldest stored first running-weigh-scale one-minute average and the power draw deviation to obtain a targeted running-weigh-scale average; (h) comparing the targeted running-weigh-scale average to the newest stored one-minute average from the first running-weigh-scale to obtain a deviation for the targeted value if one exists; and (i) 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 extrusion thickness in accordance with the amount of deviation and the take-away speed of the belt.

Claim 11

In a process comprising an extruder for providing a continuous sheet length of elastomeric extrusion, a variable speed take-away belt conveyor to vary the thickness of the extrusion as it exits the extruder, a first running-weigh-scale to measure the weight per unit area of the continuous extrusion, a cooling train to set the extrusion, and a second running-weigh-scale to measure the weight per unit area of the cooled extrusion, apparatus for controlling the thickness of the extruded elastomer comprising: (a) means to sample the weight of the extrusion at the first running-weigh-scale each second; (b) means to compute and store one-minute averages of the first running-weigh-scale samples; (c) means to sample the power draw at the extruder each second; (d) means to compute and store one-minute averages of the power draw samples; (e) means to condition the oldest and newest stored power draw one-minute averages to a constant "k" indicative of the characteristic of the extruded material to obtain a power draw deviation if one exists; (f) means to periodically sample the weight of the extrusion at the second running-weigh-scale; (g) first comparator means to compare the second running-weigh-scale sample to the oldest stored first running-weigh-scale one-minute average and the power draw deviation to obtain a targeted running-weigh-scale average; (h) second comparator means to compare the targeted running-weigh-scale average to the newest stored first running-weigh-scale one-minute average to obtain a deviation for the targeted value if one exists; and (i) means to convert the deviation of the targeted value to a control signal for increasing or decreasing the speed of the take-away belt to vary the extrusion thickness in accordance with the amount of deviation and the take-away speed of the belt.

Claim 12

In a process comprising an extruder for providing a continuous sheet length of elastomeric extrusion, a variable speed take-away belt conveyor to vary the thickness of the extrusion as it exits the extruder, a first running-weigh-scale to measure the weight per unit area of the continuous extrusion, a cooling train to set the extrusion, and a second running-weigh-scale to measure the weight per unit area of the cooled extrusion, apparatus for controlling the thickness of the extruded elastomer comprising: (a) means to sample the weight of the extrusion at the first running-weigh-scale each second; (b) means to compute and store one-minute averages of the first running-weigh-scale samples; (c) means to sample the power draw at the extruder each second; (d) means to compute and store one-minute averages of the power draw samples; (e) means to condition the oldest and newest stored power draw one-minute averages to a constant "k" indicative of the characteristic of the extruded material to obtain a power draw deviation if one exists; (f) means to periodically sample the weight of the extrusion at the second running-weigh-scale; (g) first comparator means to compare the second running-weigh-scale sample to the oldest stored first running-weigh-scale one-minute average and the power draw deviation to obtain a targeted running-weigh-scale average; (h) second comparator means to compare the targeted running-weigh-scale average to the newest stored first running-weigh-scale one-minute average to obtain a deviation for the targeted value if one exists; and (i) means to convert the deviation of the targeted value to a control signal for increasing or decreasing the speed of the take-away belt to vary the extrusion thickness in accordance with the amount of deviation and the take-away speed of the belt.