Data processing: software development – installation – and managem – Software program development tool – Translation of code
Reexamination Certificate
1998-12-31
2001-07-10
Powell, Mark (Department: 2122)
Data processing: software development, installation, and managem
Software program development tool
Translation of code
C717S152000
Reexamination Certificate
active
06260188
ABSTRACT:
BACKGROUND
This invention relates to apparatus and methods for automatically monitoring and evaluating manufacturing processes, for example operations which produce an ongoing stream of outputs such as discrete absorbent articles effective to absorb body fluids, for example disposable diapers. Such absorbent article products are typically fabricated as a sequence of work pieces being continuously processed on a continuous web and/or continuous processing line. Such absorbent article product generally comprises an absorbent core confined between a moisture impervious baffle of e.g. polyethylene and a moisture pervious body side liner of e.g. non-woven fibrous material. The absorbent articles are typically made by advancing one of the webs along a longitudinally extending path, applying the absorbent core to a first one of the webs, and then applying the second web over the combination of the first web and the absorbent core. Other elements such as elastics, leg cuffs, containment flaps, waste bands, and the like are added as desired for the particular product being manufactured, either before, during, or after, applying the second web. Such elements may be oriented longitudinally along the path, or transverse to the path, or may be orientation neutral.
Typical such manufacturing processes are designed to operate at steady state at a pre-determined set of operating conditions. A typical such process has a beginning and an end, and has a start-up period corresponding with the beginning of the operation of the process, and a shut-down period corresponding with the end of the operation of the process. The start-up period of the operation generally extends from the initiation of the process to the time the process reaches specified steady state conditions. The shut-down period of the operation generally extends from the time the process leaves steady state conditions to the termination of operation of the process.
While the process is operating at steady state conditions, the result desired from the process is desirably and typically achieved. For example, where the process is designed to produce a certain manufactured good, acceptable manufactured goods are normally produced when the process is operating at specified steady state conditions.
As used herein, “steady state” conditions represents more than a single specific set of process conditions. Namely, “steady state” represents a range of specified process conditions which correspond with a high probability that acceptable goods will be produced, namely that the products produced will correspond with specified product parameters.
Known statistical models and control models are based on assumptions that the goods produced during operation of a given such process represent a single homogeneous population of goods. The focus of such statistical models and control models is based on steady state conditions.
However, actual operation of many manufacturing processes, including highly automated processes, typically includes the occurrence of periodic, and in some cases numerous, destabilizing events. A “destabilizing event” is any event which upsets, interferes with, or otherwise destabilizes the ongoing steady state characteristics of either process parameters or unit-to-unit product parameters. A typical such destabilizing event is one which either causes unacceptable product to be made, or which causes the process controller to detect and/or report an anomalous condition, or both.
Depending on the nature and severity of any given destabilizing event, the destabilizing event may lead to any one or more of a number of possible results, for example, shutting down of the operation, speeding up or slowing down of the operation, changing one or more of the other operating parameters, sounding of an alarm to alert an operator, or the like. Upon the occurrence of such destabilizing events, the products fabricated by such manufacturing operation may be moving out of the tolerance range of predetermined required specifications whereupon corrective action should be taken in the manufacturing operation; or the product stream may move outside such specifications and should be culled from the product stream.
A variety of possible events in the manufacturing operation can cause the production of absorbent articles which fall outside the specification range. For example, stretchable materials can be stretched less than, or more than, desired. Elements can become misaligned relative to correct registration in the manufacturing operation. Timing between process steps, or speed of advance of an element, can be slightly out-of-tolerance. If such non-catastrophic changes in process conditions can be detected quickly enough, typically process corrections can be made, and the variances from target conditions can accordingly be reduced, without having to shut down the manufacturing operation and without having to cull, and thereby waste, product.
Other destabilizing events require more drastic action. Typical such more drastic destabilizing events are splices in any of the several inputs being fed into the process, web breaks, defective zones in an input material, the start-up period, the shut-down period, and the like. Typical responses to such more drastic anomalous destabilizing events might be culling product from the output, sending one or more corrective control commands to control actuators on the process line, sounding an alarm, slowing down the processing line, shutting down the process line, and the like.
A variety of automatic product inspection systems are available for routine ongoing automatic inspection of product being produced on a manufacturing line and for periodically and automatically taking samples for back-up manual evaluation. Indeed, periodic manual inspection of product samples is still important as a final assurance that quality product is being produced. The question to be addressed in that regard is directed toward timing and frequency of sampling and corresponding manual inspection and evaluation.
Where product is outside the specification range, and should be culled, it is desired to cull all defective product, but only that product which is in fact defective. If too little product is culled, or if the wrong product is culled, then defective product is inappropriately released into the stream of commerce. On the other hand, if product which in fact meets product specification is culled, then acceptable product is being wasted.
Body fluid absorbing absorbent articles such as are of interest herein for implementation of the invention are typically manufactured at speeds of about 50 to about 1200 articles per minute on a given manufacturing line. Accordingly, it is impossible for an operator to manually inspect each and every article so produced. If the operator reacts conservatively, culling product every time he/she has a suspicion, but no solid evidence, that some product may not meet specification, then a significant amount of in fact good product will have been culled. By contrast, if the operator takes action only when a defect has been confirmed using visual or other manual inspection, defective product may already have been released into the stream of commerce before the defective condition is discovered.
One way for the operator to inspect the product for conformity with the specification range is for the operator to periodically gather and inspect, off-line, physical samples of the product being produced. Random such inspections stand little prospect of detecting temporary out-of-specification conditions or of identifying leading and/or trailing elements of a group of defective products being produced. Where such samples are taken by an operator in response to a suspected out-of-specification condition, given the high rate of speed at which such articles are manufactured, by the time the operator completes the inspection, the suspected offensive condition may have existed long enough that questionable or defective product will have either been shipped or culled without the operator having any solid basis on which to m
Bett Thomas Arthur
Lindeke Anne Marie
Ungpiyakul Tanakon
Holmes Michael B.
Kimberly--Clark Worldwide, Inc.
Powell Mark
Wilhelm Thomas D.
Yee Paul Y.
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