Technology:
I2S continuously strives to improve the technology of the metals processing industry. Please contact us if we can answer any questions regarding our technology development and capabilities. Read about our development of a Field Programmable Grid Array (FPGA) motion control system.
Automatic Gauge Control - AGC

I2S has designed, manufactured, installed and started up well over one hundred computerized Automatic Gauge Control Systems based on the mass flow equation. In the words of our customers, these systems are “outstanding performers.”  I2S, LLC has installed AGC on one way mills, reversing mills, tandem mills, Two-Highs, ST 20 High Cluster Mills and combination Four-High / Z-High Mills.

The I2S, LLC Computerized AGC System has two modes of operation:
  1. Computerized adaptive feed forward control using the mill screwdown as means of correction also referred to as a "Mass Flow".
  2. "After the fact" control using only the exit gauge
The Mass Flow Method of Gauge Control The basic adaptive feed forward system uses the following inputs:
  • Entry Thickness Gauge
  • Exit Thickness Gauge
  • Entry Pulse Generator
  • Exit Pulse Generator
  • Separating Force
  • Mill Modulus
The basis for the mass flow gauge control is that the volume of metal that is entering the mill is equal to the volume of metal leaving it. The basic equation is:  Lin x Tin x Win = Lout xTout x Wout.  The philosophy is to compute the thickness of the strip leaving the roll bite in the smallest practical increment of strip travel and issue proportional corrections to the mill screwdown.  By utilizing this robust mathematical model, thickness control is optimized even while running slowly and during speed changes.
The exit thickness gauge is used as a master reference, and this gauge is read and averaged every time the primary loop is read (Volume in = Volume out). If the primary loop is not maintaining the exact desired thickness, it is adjusted slightly to bring the average output strip thickness deviation to zero. This cycle of events is repeated on a continuous basis and system adjustments are made as necessary.

The “After the Fact” Method of Gauge Control
The other mode of gauge control is the exit feedback method. This is called “After the Fact”, on legacy mills "GB-100". This mode uses only the exit gauge for making corrections to the screwdown.  One tach, either driven off the exit side of the mill, or the mill tach (whichever is available), is used to initiate the corrections.  It is based on the assumption that the thickness of the metal in the roll gap is the same as the thickness at the gauge.  It reads the gauge over a short interval and averages these readings to get a better idea of the thickness of the metal at the roll gap.  If this averaged thickness is different than the desired thickness, the mill screwdown is issued a command to move a proportional amount based on mill modulus and separating force.

This system is used on the loading pass from the payoff, when entry side pulse tach or strip thickness gauge cannot be used.
Elongation Control
The I2S elongation control system acquires elongation comparison signals by means of two high resolution tachometers (entry & exit). A tach termination board processes the signals into the tach interface board contained in the industrial IBM compatible computer.

I2S' elongation software then analyzes the tach signals. By comparing the measured "length in" with the measured "length out" of the strip, the actual elongation is calculated. If the specified elongation is not being achieved, the screwdown control board sends movement commands to the hydraulic screwdown system. Adjustments in the screwdown force increase or decrease the elongation to match the specified elongation setpoint value entered by your operator.

The I2S elongation control system continuously monitors the actual elongation to make sure you achieve your customers' specifications, consistently. For more information on applying our elongation technology to your company's particular production, please contact a representative in our sales department.




Statistical Process Control - SPC

Why SPC?  Prevention vs. Detection
A traditional approach to manufacturing is to depend on production to make the product and on quality control to inspect the final product and screen out items not meeting specifications.  In administrative situations, work is often checked and rechecked in efforts to catch errors.  This is wasteful because it allows time and materials to be invested in products or services that are not always useable.  After-the-fact inspection is uneconomical;  it is expensive and unreliable, and wasteful production has already occurred. (*)

A prevention strategy sounds sensible -- even obvious -- to most people.  It is easily captured in such slogans as, “Do it right the first time.”  However, this kind of cheerleading is not enough.  What is required is an understanding of the elements of a Statistical Process Control system. (*)

The I2S, LLC SPC data gathering system is largely based on the methods and interpretations as outlined in the Ford Motor Company’s publication listed in the footnote below.

(*)  Taken from the Ford Motor Company’s booklet number 80-01-251 “Continuing Process Control and Process Capability Improvement”  September 1985.

Overview of the SPC/QC System
We sample the gauge deviations from the exit gauge and use them to generate range and average charts.  Standard deviations and Cpk values are also calculated.

While the mill is running we also display range and average charts on the screen, a kind of ”SPC on the fly.”  These charts are constantly being updated while the strip is being rolled and provides instant feedback to the operator on how the gauge quality is being maintained.  There are also screens on the computer that enable the setting of specification limits, full scale ranging for the charts and other setup information.

At I2S, LLC we do not stop our quality reporting with these SPC charts, we also provide other optional methods of inspecting gauge control quality.

It is a crucial part of business today that for every process control system there is a flexible, easy to use, quality control system that can be used to monitor performance.  With the I2S, LLC automatic gauge control coupled with the SPC/QC reporting package, control and verification go hand in hand.