Optics: measuring and testing – Inspection of flaws or impurities
Reexamination Certificate
2000-07-26
2002-10-08
Pham, Hoa Q. (Department: 2877)
Optics: measuring and testing
Inspection of flaws or impurities
C348S125000, C073S865800
Reexamination Certificate
active
06462811
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to the inspection and measurement of cutting tools and particularly to video camera-based systems and methods for inspecting and measuring each tooth of a multitooth saw blade.
2. Description of the Prior Art
To provide a high degree of cutting efficiency, accuracy and safety, the geometry of the teeth of multitooth circular saws as well as the straightness or flatness of the saw blade plate must be accurately maintained. To this end, industrial quality control systems have been developed for optically inspecting and measuring the geometries of the individual saw blade teeth and for grinding or, if necessary, replacing those teeth whose geometries fall outside prescribed limits. Saw blade plate runout, that is, the displacement of the blade from a reference plane, is also measured and, if necessary, the trueness of the blade is restored using special bending equipment.
Rapid and accurate inspection and measurement techniques are especially needed for the maintenance of present day thin kerf circular saws having small carbide teeth. By way of example, such teeth may have a kerf of only 1.3 mm yet have relatively complex geometries that cannot be efficiently inspected and measured manually or by conventional optical techniques. Thus, there have been developed systems for inspecting and measuring the teeth of carbide tooth saw blades that rely on a video camera to provide a magnified image of individual saw teeth. Computer software is used to analyze each tooth and provide visual inspection and measurement capabilities.
A video camera-based apparatus for inspecting the teeth of carbide tooth saw blades is disclosed in U.S. Pat. No. 5,861,564 issued Jan. 19, 1999. The apparatus of the '564 patent includes a base upon which the saw blade to be inspected is movably mounted to permit positioning the saw blade to bring each tooth of the blade to a viewing location. A single video camera is mounted on an arm carried by the base. The arm is pivotable about first and second axes permitting the camera to be moved to various positions in succession to view the face, top and side of a given tooth positioned at the viewing location.
Although the apparatus of the '564 patent permits inspection and measurement of three major surfaces (face, top and side) of an individual saw tooth, it requires manual adjustments in order to make measurements of each tooth. Thus, the saw blade must be angularly indexed manually to bring each tooth within the viewing location. Following imaging of the tooth face, the arm carrying the video camera is then unlocked and manually rotated from its vertical position approximately 90° about the first axis and locked in place to position the camera to image the tooth top. Next, the arm is unlocked and raised back to its vertical position, then rotated about the second axis approximately 90° to a horizontal position to permit imaging of the tooth side. These adjustments are time-consuming and must be made for each tooth of a saw blade which may have several dozen teeth. Moreover, the apparatus of the '564 patent is incapable of measuring the plate runout of the saw blade being inspected.
Accordingly, there is a need for a video camera-based saw tooth inspection and measurement system and method that is more automated, that is, that eliminates the aforementioned manual steps to thereby reduce the time for saw blade tooth inspection and measurement. In addition, there is a need for an automatic tooth system and method that provide for the measurement of saw blade runout and does so automatically for various angular positions along the saw blade.
SUMMARY OF THE INVENTION
In accordance with one specific exemplary embodiment of the invention, there is provided a system for inspecting first and second surfaces of a cutting member, such as a tooth of a carbide tooth circular saw blade, includes a support for carrying the cutting member, the cutting member being movable relative to the support to position the surfaces to be inspected within an inspection zone. First and second video cameras mounted on the apparatus relative to the inspection zone provide output signals representative of the images of the first and second surfaces, respectively. A computer responsive to the output signals generated by the first and second video cameras analyzes the output signals and calculates selected attributes of the surfaces presented for inspection. A frame grabber captures video images of the surfaces. A first video monitor coupled to the computer displays images of the surfaces being inspected while a second video monitor coupled to the computer displays graphical data relating to selected geometrical attributes of the surfaces. The system utilizes the video image data and an appropriate algorithm to control a servo motor to accurately position the cutting member in the field of view. Upper and lower semicircular light transmitters, coupled to a light source, surround the inspection zone to uniformly illuminate the zone and provide a sharp contrast between the surfaces under inspection and the background.
In accordance with another specific embodiment of the invention, there is provided a method for inspecting first and second surfaces of a cutting member, such as a tooth of a carbide tooth circular saw, using first and second video cameras, respectively, the method comprising the steps of moving the cutting member to position the first and second surfaces within an inspection zone, providing electrical video signals from the first video camera representative of the image of the first surface presented for inspection, storing a frame of said video signals provided by the first video camera, providing electrical video signals from the second camera representative of the image of the second surface presented for inspection, storing a frame of said video signals provided by the second camera, and displaying the stored frames.
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patent: 3410149 (1985-10-01), None
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PCT International Search Report dated Oct. 20, 2000 re International No. PCT/US 00/20345, international filing date Jul. 26, 2000.
Trinchera Salvatore R.
Turner James P.
Zierdt Charles H.
California Cedar Products Company
Koppel, Jacobs Patrick & Heybl
Pham Hoa Q.
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