Image analysis – Applications – Manufacturing or product inspection
Reexamination Certificate
1998-12-31
2002-06-11
Ahmed, Samir (Department: 2623)
Image analysis
Applications
Manufacturing or product inspection
C700S124000
Reexamination Certificate
active
06404910
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to apparatus and methods for monitoring and evaluating manufacturing operations which produce an ongoing stream of discrete absorbent articles effective to absorb body fluids. Such products are typically fabricated as a sequence of work pieces on a continuous web. Such absorbent articles generally comprise 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 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. 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 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.
Upon the occurrence of certain events, the products fabricated by such manufacturing operations may be moving out of a tolerance range of predetermined required specifications whereupon corrective action should be taken in the manufacturing operation; or the product may fall 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 reduced, without having to shut down the manufacturing operation and without having to cull, and thereby waste, product.
Certain events, however, inherently result in production of out-of-tolerance product whereby no amount of process control can avoid product culling. Exemplary of such events are splices in the base continuous web.
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. If product which in fact meets product specification is culled, the good product is being wasted.
Body fluid absorbing absorbent articles 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 hand 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. However, if the operator takes action only when a defect has been confirmed using visual inspection, defective product may already have been released into the stream of commerce.
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. Where such samples are taken 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 his/her inspection, the suspected offensive condition may have existed long enough that questionable product will have either been shipped or culled without the operator having any solid basis on which to make the ship/cull decision. Further, automated manufacturing process controls may have self-corrected the defect condition before the operator can complete the visual inspection and act on the results of such visual inspection.
While off-line inspection is the primary determinant of quality, and defines the final quality and disposition of the product, on-line inspection, and off-line inspection of on-line-collected data, typically associated with certain manufacturing events, may provide valuable insight into both the operation characteristics of the manufacturing process, and the final quality parameters of the product.
Recent advances in product inspection include use of one or more vision imaging systems having a camera disposed along the path of manufacture. A vision imaging system camera can thus be placed in a fixed location, for collecting visual images of the product at that location. The vision imaging system continuously collects images of the product work pieces as the product precursors pass the point in the manufacturing process which is being monitored. The images so collected are transmitted to a visual display device such as a video monitor at the operator's station, whereby the operator can visually monitor certain visual parameters of the product at the respective location along the manufacturing path.
Such vision imaging systems typically run continuously during manufacturing operations, such that the operator can continuously, or at any time, monitor the condition of the product being manufactured at the given location in the manufacturing line. However, conventional continuous-duty vision imaging systems do not provide any mechanism for the operator to archive any images being viewed.
Some current vision imaging systems can be used to instantaneously capture the full digital representation of a vision image, and to capture and transfer measurement data representing limited portions of each of the images to be evaluated, but have very limited ability to store or transfer full visual images related to that data. The memory storage capacity of such vision imaging systems provides a limited capacity for temporarily or permanently storing vision images so collected. The collected images and data can be transferred to permanent storage within the vision imaging systems, but the imaging system has very limited capacity to permanently store the images, and such permanent storage will compromise the ability to continue collecting data while simultaneously transferring collected data to permanent storage at the production speeds contemplated here of, for example and without limitation, at least 200 inspections per minute.
The capacity to simultaneously collect data, and transfer data to permanent storage, is a function of both the complexity of the inspection of images being captured and analyzed, and the frequency with which images are to be captured. At typical manufacturing speeds for manufacturing absorbent articles such as diapers and incontinence products, namely at least 300-400 units per minute, current vision imaging systems are unable to sustain required rates of ongoing simultaneous capture and transfer of the images available for capture at the rate of one image per unit of production.
Removal or transfer of the data, and restarting of the collection process in such existing vision imaging system typically includes operator intervention, but can be done by pre-programmed computer control. While limited amounts of data can thus be collected and archived from a high speed operation such as illustrated in the drawings, the amount of data which can be collected relating to a given event is quite limited. Typically, current imaging systems will freeze on the first defective image detected. Restarting of the collection process can be pre-programed and thus computer controlled, or can be manual. Accordingly, to the extent the ongoing manufacturing process is producing data that could be useful to the operation and/or analysis of the process
Bernhardt Wayne Allen
Bett Thomas Arthur
Lemery Shawn Timothy
Ungpiyakul Tanakon
Ahmed Samir
Kimberly--Clark Worldwide, Inc.
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