Television – Special applications – Manufacturing
Reexamination Certificate
1998-12-04
2001-12-11
Lee, Richard (Department: 2613)
Television
Special applications
Manufacturing
C348S135000
Reexamination Certificate
active
06330024
ABSTRACT:
TECHNICAL FIELD
This invention pertains to the art of methods and apparatuses for measuring the quantity of material in a calender bank, and more specifically to methods and apparatuses for using digital imaging technology in a system for measuring and controlling the size and shape of a rolling calender bank. While the invention will be described in terms of processing an elastomeric material, the invention is also applicable to other materials such as pizza dough, plastics, paper pulp, or any material in which a bank is formed on a mill, calender or similar machine.
BACKGROUND ART
The size and shape of the rolling bank on a calender or mill is an important component in the calendering process. The bank provides a buffer to keep a uniform supply of material to the calender rolls. However, if the bank is not maintained at proper level, nonuniformities can appear in the calendered sheet. For example, if the bank is too low, voids can be formed in the sheet due to the “starved” condition of the bank. On the other hand, if the bank is too large, problems such as material scorching can occur, which produces cured or otherwise undesirable lumps in the sheet of material. In addition, variation in rolling bank size causes variation in the spreading force on the rolls resulting in uneven gauge of the sheet.
The ability to accurately control the size of the calender bank provides more uniform results in the calendered sheet in terms of component dimensions and composition. Inherent in the problem of controlling the bank size is the problem of being able to accurately measure the quantity and distribution of material present in the bank.
In the art, there have been a variety of methods and apparatuses employed in attempts to solve the problems associated with determining the bank size. For example, a method disclosed in U.S. Pat. No. 4,642,686 to Nagono et al. utilizes a video camera, a screen, and a light source to obtain a silhouette of the banked material. The area of the silhouette is then related to a quantity of material. The method involves a backlighting arrangement which is more complex than the inventive method.
Japanese Document No. 59-132314 to Yonezawa et al. discloses a method by which a television camera records a picture of a pair of blank rolls and then records a picture of the rolls having a bank of rubber therebetween. The difference between the pictures is obtained by a subtractor. The picture elements are then converted to black and white binary signals wherein the rubber is indicated in black. A correction means converts black portions which are below a predetermined width to white. This direct method of obtaining binary signals does not compensate for the problem of glare commonly encountered when shiny calendering rolls are employed.
European patent application 0 645 230 A1 to Hatanaka is also directed to a device for adjusting the quantity of a bank of material on a mill.
The present invention provides new and improved means for measuring and controlling the quantity of elastomeric material formed in a bank between two calendering rolls in a way which simply and effectively overcomes the problems currently encountered in the art.
DISCLOSURE OF INVENTION
In accordance with the practice of the present invention, there is provided a method for measuring the quantity of elastomeric material formed in a bank between two calendering rolls.
More particularly, in accordance with the present invention, a method utilizing digital images obtained by camera means trained on the calendering rolls is provided.
In accordance with one aspect of the invention, the method utilizes initial and secondary digital images comprising pixels having numerical values relating to lighter and darker hues. The initial image is obtained when the elastomeric material is absent and the secondary image is obtained when said elastomeric material is present. The inventive method is characterized by the steps of:
combining the initial and secondary images to form a third digital image wherein the elastomeric material is indicated by lighter hues;
excluding a portion of the third image which corresponds to the presence of the elastomeric material on a surface of the second roll;
measuring an area of lighter hues; and,
relating the area to the quantity of elastomeric material in the bank.
In accordance with another aspect of the invention, the third digital image is optionally multiplied by an integer constant to increase a contrast between lighter and darker hues.
In accordance with another aspect of the invention, the numerical values of each of the pixels of the third digital image are compared to a predetermined standard, and values above the standard are converted to pure white hues, and values below the standard are converted to pure black hues.
In accordance with another aspect of the invention, the third digital image is corrected for perspective and lens distortion.
In accordance with another aspect of the invention, the number of pixels corresponding to the lighter hues are compared with a total number of pixels in the third digital image to obtain a fraction of the image corresponding to the elastomeric material. A calibration matrix is then utilized to convert the fraction to an actual cross-sectional area of elastomeric material present in the bank.
In accordance with another aspect of the invention, a method for controlling the quantity of elastomeric material contained in a bank between calendering rolls in a calendering apparatus is provided. The method utilizes initial and secondary digital images comprising pixels having numerical values relating to lighter and darker hues. The initial image is obtained when the elastomeric material is absent and the secondary image is obtained when the elastomeric material is present. The inventive method is characterized by the steps of:
combining the initial and secondary images to form a third digital image wherein the elastomeric material is indicated by lighter hues;
excluding a portion of the third image which corresponds to the presence of the elastomeric material on a surface of the second roll;
measuring an area of lighter hues;
relating the area to a total quantity of the elastomeric material in the bank;
comparing the total quantity of the elastomeric material in the bank with a predetermined optimal quantity; and,
adjusting a feed rate of the elastomeric material to the calendering apparatus.
In accordance with another aspect of the invention, the elastomeric material is fed to the bank through a plurality of feed lines. In addition, the third digital image is divided into a plurality of zones, each zone corresponding to a region of the bank being fed by one of the feed lines. The quantity of elastomeric material contained in each of the regions is determined and compared to the total quantity of elastomeric material in the bank. The quantity of elastomeric material in each region is further be compared to the optimal quantity of elastomeric material in the bank.
In accordance with another aspect of the invention, the distribution of elastomeric material through each feed line is altered to optimize the quantity of elastomeric material in each region of the bank.
In accordance with another aspect of the invention, a system for determining the quantity of elastomeric material contained in a bank between first and second closely juxtaposed calendering rolls in a calendering apparatus is provided. The system utilizes initial and secondary digital images obtained by camera means trained on said rolls. The inventive system is characterized by:
combining means for combining the initial and secondary images to form a third digital image wherein the elastomeric material is indicated by lighter hues;
excluding means for excluding a portion of the third image which corresponds to the presence of the elastomeric material on a surface of the second roll;
measuring means for measuring an area of lighter hues; and
converting means for converting the area to the quantity of elastomeric material in the bank.
In accordance with another aspect of the in
Frerking, Jr. Harlan William
Vargo Richard David
Emerson Roger D.
Lee Richard
The Goodyear Tire & Rubber Company
The Goodyear Tire & Rubber Company
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