Exergen IRt/c’s Used With Heated Metal Rollers To Increase Production

By employing Exergen IRt/c sensor technology, a significant increase in high quality output of web processing can be accomplished. Use the IRt/cs with stainless steel, chrome plated or other uncoated metal rollers. IRt/c systems enable users to

Increase throughput speeds up to 20%, or more, on the same machine
Reduce scrap up to 75% or more
Reduce set­up times
Process a greater variety of web materials on the same machine

Applications / Processes that would profit from the use of IRt/c technology:

Opaque films processing
Textile processing
Paper processing
Any continuous web processes using heated (or cooled) rollers

Use of Exergen’s unique patented, non­contact infrared sensors resolves earlier technical problems related to temperature measurement of shiny, uncoated metal rollers (because of the high infrared reflectivity of the uncoated metal surfaces). Exergen has developed and analyzed a two-stage method to accurately measure and control the heat output of heated (or cooled) metal rollers using the IRt/cs—even at extremely high speeds.

Stage 1: Startup and Standby Temperature Control

During start­up and stand­by conditions, the temperature of the heated roller will become uniform across the roller surfaces. The temperature can be reliably measured at any suitable location on the surface, or the edge, of the rollers. For Stage 1, merely install an IRt/c so that it can monitor a reliable signal from the roller

Running Temperature ControlUncoated Metal Rollers

On an unused edge of the roller, install a durable non­metallic target surface finish. This can be done with:

(a) a durable epoxy paint
(b) the incorporation of a thin metallic hoop, or ring, with a Teflon coating
(c) or the addition of a thin hoop, or ring, of black, hard anodized aluminum

Set up an IRt/c sensor that monitors this coated surface. Use this sensor to regulate the temperature of the roller. This is during start­up and stand­by modes.

Coated Metal Rollers (Teflon, silicon coating, any non metallic coating, etc.)

Install an IRt/c to aim at the center, or any suitable location, on the surface of the roller.

Stage 2: Running Temperature Control

For Stage 2, install an extra IRt/c sensor to directly monitor the web surface after it contacts the heated roller. As the web starts to move, (or, at a preset rpm) the temperature control system for the roller should be turned over to a control system connected to this IRt/c sensor.

This IRt/c sensor is mounted that it monitors the side of the web material that is heated. For webs heated on two sides, sensors should be mounted on each side to regulate each heated roller.

Multi­zone Rollers: use at least one IRt/c for each zone across the web.

Wide Webs: multiple IRt/c sensors are installed across the web.

Explanation

The most typical errors in web processing are as follows:

Temperature Measurement Errors ­ –  Incorrect Temperature Measurement

Internal temperature sensor location errors
Thermocouple “Slip ring” signal errors

Heat Transfer Errors ­ Errors caused by variations of heat transfer to the web.

Changes in pressure applied to the web as it touches the heated roller
Web material changes in moisture content, thickness, etc.
Dirt build­up on the heater roller surface that can hinder heat transfer to the web

As the roller accelerates, heat is taken away from the roller surface by the web material. Temperature gradients show up inside the roller, and on the roller surface. Conventional embedded, surface, or edge temperature sensors cannot effectively track and compensate for all these temperature differences, nor can they sufficiently measure the quantity of heat transferred to the web material.

Exergen’s Two Stage IRt/c Sensor & Control System automatically decreases all these sources of web temperature processing errors. Therefore, the actual temperature of the webs can be both closely (to within a few degrees) and dependably controlled using IRt/c sensor technology. The robust IRt/c sensors do not require power supply and periodic calibration. Their design is for years of trouble-free operation.

Exergen Corporation is the global leader in industrial and medical non­invasive temperature technology. Design and manufacturing take place in Watertown, the suburbs of Boston. Exergen, known for its award-winning temporal artery thermometer in the healthcare and consumer market, was based by Harvard research scientist Dr. Francesco Pompei. Dr. Pompei holds over 75 patents.