Automatic Gauge Control System

Automatic Gauge Control System

Walco's Next Generation of Automatic Gauge Control Technology Enhances Metal Output Quality with Heightened Speed, Performance and Consistency.

The next generation of automatic gauge control system technology from Walco efficiently solves the classical problems presented by outdated closed-loop AGC systems on cold reduction mills. Closed-loop technology makes measuring the strip gage at the roll bite impossible. This necessitates downstream measuring that gives rise to a transport which creates waste, added costs of downtime and inefficiency.

The Power of Advanced DSP Technology

Walco's AGC System has been developed with the latest technology using "off-the-shelf" components. The brain of our AGC system is an advanced Digital Signal Processor (DSP) motion control processor. Powered by an 80MHz Motorola DSP56303 processor, the DSP performs all AGC calculations providing critical analog and digital interfaces to the rolling mill. The DSP processor rack is connected directly to a host computer via USB or industrial Ethernet interface. And because our AGC program runs on the DSP, there is no delay in issuing roll position corrections. In fact, the DSP calculates gage errors every 0.001328 seconds! Once the gage error has been calculated and sent to the roll position system target register, the system immediately moves to the new target position.

The DSP processor used by Walco’s AGC system performs the following functions:

  • Mass Flow and Feedback AGC
  • Closes the position loop on the hydraulic cylinder(s)
  • Feed-forward component to the final AGC correction
  • Low pass, high pass and anti-alias filtering of AGC component signals
  • Gathering of all quality control information required by the host PC
  • Multi-step mill auto-stop algorithm
  • Variable mill speed defect tracking (multi-point slowdown)
  • Left and right winder wrap counters
  • Rolling force calculation
  • Gathers all analog channels and performs unit scaling
  • Gathers all digital inputs and de-bounce signals
  • Joystick control of roll position cylinders
  • Roll position system cylinders close to force calculations and operation
  • All rotary encoder integrity tests including wrong encoder counts, missing A or B channel, improper channel phasing, and over frequency
  • DSP-to-host computer USB or Ethernet communication.

Mass Flow Advantages

Walco’s AGC system employs constant mass flow theory enhanced with digital filtering, an entry gage error feed-forward component and a rotary buffer for storing entry and exit length information. The system retains the downstream thickness gage as a final arbiter of strip thickness, as any AGC system must do. The constant mass flow system obtains quick, accurate response by measuring the length of the strip at entry and exit sides of the mill, and also measuring entry gage. The entry gage is sampled every 10 mm of entry strip movement and stored in a memory buffer in the DSP. The entry gage samples are recalled from memory after that segment of the material reaches the roll bite. The gage control computer knows the exact instant when this measured segment reaches the roll bite due to the high resolution strip driven encoder arm that measures the entry strip length.

Walco’s AGC system features these new enhancements:

  • All analog channels have separate high voltage "analog isolators" to remove any potential problems related to ground loops
  • All analog input signals utilize 16-bit high-speed 5-microsecond A/D converters
  • Blazing fast data transfer from DSP to the host computer using USB or Ethernet communications
  • Color graphic touch screen operator interface
  • All Windows XP supported printers may be used
  • Direct network connection of the host computer
  • All digital signals are multiplexed and de-bounced
  • Customer can easily edit a text file to change any system parameters
  • Tasks on the DSP processor card are rapidly compiled into DSP56303 assembly language

strip test technology in AGC systemsComputerized Strip Chart Technology

Windows XP integration into the ACG system enables the printing of the exit linear strip thickness profile on a graphics printer eliminating slow and sloppy two-pen chart recorders. The response time of the computerized strip chart is 5 milliseconds – at least 4 times faster than the best analog recorders. The SPC printout is metric and contains date, time, mill run time, average and maximum speed as well as comprehensive entry and exit data including nominal thickness, total meters, standard deviation, mean thickness, and a histogram with 60 different categories.

Why Walco

Founded in 1931, Walco has become one of the largest electrical apparatus service facilities in the northeast. Walco has built a rich tradition of integrity, innovation and a commitment to customer service like none other. Walco helps customers across the U.S. and around the world stay productive utilizing Walco's advanced technology, state-of-the-art facilities, superior training, a culture of high performance, safety and educational sharing.

We provide support 24/7, 365-days-a-year and stand behind what we do. Walco will be here long after the job is complete with an organization unparalleled in its dedication to your success. There’s a reason we say "Never Underestimate the Power of Total Commitment".