A Communication from the PLACE Div. of TAPPI

Providing practical information to the converting and packaging industries…

Automatic Servo Positioned Air Knife Systems for Optimal Cast Film Quenching
by Fred Suppon and Beth Wells, Black Clawson Converting Machinery, Inc.

APPLICATION: A servo positioned air knife system with enhanced manual features provides multiple axis position repeatability, stable air pressure and velocity, consistent air temperature control, and a user friendly set up.
The days of cast film manufacturers running the same product day after day without changeover are fast becoming something of the past. With demands increasing for more custom blends, bringing new products to market, and shorter runs, the film industry has seen a need for quicker changeover between products, less down time, less set up time and the ability to meet specifications on a product in less time from start up. One response to this demand is an innovative new servo positioned air knife system with enhanced manual features developed to help address these issues by providing numerous advantages.

These features have all been combined into one system that provides optimal cast film quenching and gentle pressure to lay the film smoothly on the chill roll. It also minimizes the entrapped air layer between the film and the chill roll with superior repeatability over traditional air knives. This paper examines these and other features and lists expected benefits.

To address air knife position with relation to the die and chill roll, this system allows three modes of mobility. They are vertical (orbital around the chill roll axis), radial (linear position from the chill roll surface), and angle of the air knife lips or beak. Each axis of movement relies on control from its own servo positioning system. Repeatable positioning, stable pressure, and temperature aid the pursuit of producing the highest quality film for a converter. The automatic and manual features fully described in the paper combine into one system to give the converter an effective tool toward the goal of optimum film quality.

Inertial Measurement Of Roller Parallelism
by Sebastian Busch, PRUFTECHNIK Service, Inc.

APPLICATION: Because many web handling problems result from roller alignment issues, the inertial measurement of roller parallelism provides a new approach to solving an old problem.
Until now, roller alignment has relied almost exclusively on optical means. When measuring with optical means, line of sight between the reference line outside the machine and the rolls to be aligned is necessary. When using sticks and dial gauges for alignment in addition to line-of-sight constraints, a short distance between rolls is a requirement. If a machine is already in operation, encased areas of the machine are particularly difficult to access. This further compounds the problem. In addition, all traditional ways of alignment require a considerable amount of time for performing measurements. This often translates into an extended period of downtime.

In contrast to all conventional system, inertial alignment is a completely new approach to roll alignment. It uses highly accurate ring laser gyroscopes that have a so-called “inertia.” These high-precision instruments have become known as the backbone of navigational systems in aircraft and satellites. If a point in Cartesian space is specified as a reference point as the ideal point with the device, the device can then specify every other point in the same space with respect to its deviation from the horizontal and vertical planes. An “ideal” roller within the machine becomes a reference point. Inertial alignment stores and remembers its relative position and compares it with each subsequent roller being measured. Their relative angular position can be stored, displayed, and processed automatically, without any need for manual intervention.

By using an inertial measurement, gaining complete insight in a plant is possible. Inertial alignment allows pinpointing the root cause of a problem very quickly and accurately. It also provides the first complete picture ever performed in the lifetime of a machine.

For information about the PLACE Division of TAPPI, access the TAPPI web page at tappi.org. To obtain the complete papers whose expanded summaries appear in this section, go to the TAPPI web site at tappi.org., then click on "the PLACE" in the section designated Journals.

Telephone inquiries are welcome at the TAPPI Service Line by calling 800/332-8686 in the United States, 800/446-9431 in Canada, or 770/446-1400 in other countries. Send FAX to 770/446-6947. Address mail to TAPPI, 15 Technology Parkway South, Norcross, GA, 30092.

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