Data processing: generic control systems or specific application – Generic control system – apparatus or process – Optimization or adaptive control
Reexamination Certificate
1999-06-30
2003-04-22
Starks, Jr., Wilbert L. (Department: 2121)
Data processing: generic control systems or specific application
Generic control system, apparatus or process
Optimization or adaptive control
C700S071000, C700S110000, C700S124000, C700S129000, C702S179000, C702S180000, C702S183000
Reexamination Certificate
active
06553270
ABSTRACT:
BACKGROUND
This invention relates to apparatus and methods for automatically monitoring and adjusting manufacturing processes, for example, processes which produce an ongoing stream of outputs such as discrete absorbent articles, for example disposable diapers, effective to absorb body fluids. 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 of fabrication and assembly machines.
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 a web of either baffle or body side liner material along a longitudinally extending path, applying the absorbent core to the advancing web, and then applying the second web over the combination of the advancing 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. As added, such other elements are typically registered on the absorbent article in one or both of the with machine direction and the cross machine direction.
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 process 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 such as disposable diapers, 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 for controlling the manufacturing process 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 recognize and/or report an anomalous process condition, or both.
A typical manufacturing automatic process control system can make adjustments to the process in real time based on horizontal analysis such as averaged data collected from a pre-determined quantity, e.g. a predetermined number of serially-arranged units of work pieces currently being processed. In addition, such typical manufacturing automatic process control system can automatically cull product according to predetermined criteria upon the occurrence of a pre-defined triggering event that e.g. inherently produces at least a minimum quantity of defective product. Thus, depending on the nature and severity of a given destabilizing event, the process controller may respond to the destabilizing event by culling product and/or by making adjustments to one or more process conditions, for example, shutting down the operation, speeding up or slowing down the operation, changing one or more of the other operating parameters, sounding an alarm to alert an operator, or the like.
Upon the occurrence of such destabilizing events, the data representing products fabricated by such manufacturing operation may begin moving away from target conditions whereupon corrective action should be taken in the manufacturing operation; or the data may move outside acceptable specifications whereby the respective units of product should be culled from the product stream. However, such control systems typically collect a number of data points from sequentially arranged units of product in the stream of goods being produced, and compute a data average, before taking corrective action. In the meantime, defective product may be produced, and may subsequently be packaged for shipment.
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 become out-of-tolerance. If such non-catastrophic deviations in process conditions can be detected quickly enough after the deviation from target begins to show up in the product, 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.
In some cases, the changes are so severe, or happen so quickly, that process corrections based on such anomalies detected in the product concurrently being produced are insufficient to avoid production of defective product which must be culled.
Further, where the anomalous condition is inherently temporary and short term, by the time automatic corrective action based on currently collected anomalous data, namely horizontal analysis, can be implemented, the temporary time period during which the anomalous behavior occurs may have expired. In such event, the corrective action is applied to non-defective work pieces, risking the possibility of creating defective work pieces that would have, but for the corrective action, been within acceptable specifications.
Exemplary of destabilizing events of interest in the invention are, for example, splices in any of the several materials being fed into the process, web breaks, defective zones in an input material, the start-up period, the shut-down period, unplanned start-up and unplanned shut-down periods, and the like. Typical responses to such more drastic anomalous destabilizing events might be culling product from the manufacturing line, 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.
Where the process produces product wherein one or more elements is mis-registered on Th
Hein John Gerard
Houle Alain Christian
Lashbrook Glen Everett
Norman Andrew
Pennings Michael Earl
Barnes Crystal J.
Kimberly--Clark Worldwide, Inc.
Starks, Jr. Wilbert L.
Wilhelm Thomas D.
Wilhelm Law Service
LandOfFree
Proactive control of a process after the beginning of a... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Proactive control of a process after the beginning of a..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Proactive control of a process after the beginning of a... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3084246