Data processing: generic control systems or specific application – Specific application – apparatus or process – Product assembly or manufacturing
Reexamination Certificate
1994-07-21
2001-04-17
Gordon, Paul P. (Department: 2121)
Data processing: generic control systems or specific application
Specific application, apparatus or process
Product assembly or manufacturing
C702S155000, C144S357000, C144S416000
Reexamination Certificate
active
06219585
ABSTRACT:
SUMMARY OF THE INVENTION
1. Field of the Invention
The invention relates to a scanning device for determining the shape of irregular cylindrical objects. More specifically, the invention relates to a laser scanning device which can determine the shape of a log in three dimensions to allow a log to be properly positioned during a sawing operation in order to maximize the yield from a log.
2. Description of the Related Art
It is well known to utilize a scanner to control the position of a log during a sawing operation. A conventional log scanning system is illustrated in
FIG. 1. A
row of photoemitters
2
is positioned above log L which is movably supported on a saw apparatus by headblocks
6
. A row of photoreceivers is disposed below log L in opposition to the row of photoemitters
2
. Each photoemitter is directed toward a corresponding photoreceiver. In this manner, the outline of front edge
7
of log L can be determined as log L is moved into the path of the light emitted by the photoreceivers while simultaneously monitoring the position of headblocks
6
. An outline of back edge
8
of log L can be obtained by the relative positions of each headblock
6
(see FIG.
2
). Combining the two outlines (front edge and back edge) provides a horizontal longitudinal log profile which can be used to detect curvature of the log in the horizontal plane (see FIG.
2
). Since this type of system does not measure curvature of log L in the vertical plane, the sawing pattern of log L must be determined on the assumption that there is not curvature in the vertical plane. This assumption is usually erroneous and thus causes error in determining optimum sawing patterns (see FIG.
3
).
A primary function of a log scanner is to properly position the log with respect to a vertical sawblade so that slab can be removed on the first cut which enables the first board removed (on the second cut) to be of a minimum width and length after round edges thereof have been removed. Of course, the board must also be straight. If log position for this open face is determined by the conventional scanner discussed above, any curvature in the vertical plane will cause the resulting board to be curved. Such a board cannot be edged to the desired width unless a large amount of extra wood is removed from log L to compensate for the error. This is wasteful of time and natural resources
In addition, to the device disclosed above, it is well known to use a laser to scan a log in two dimensions as the log is moved through the path of the laser. Such a device is disclosed in U.S. Pat. No. 4,941,100 (issued Jul. 10, 1990) and is useful to allow control of a vertical edger which removes top and bottom portions of a log to allow a rectangular board to be cut. However, because such a device also determines contour in only two dimensions, it does not aid in determining the proper thickness of a slab in order to open the face of the log for optimum yield.
SUMMARY OF THE INVENTION
An object of the invention is to provide a log position control device which can accurately position the log for a sawing operation in order to maximize the yield of the log.
Another object of the invention is to position a log to allow a first cut of a saw operation to open a face of the log which is just high enough to allow the desired sized board to be cut during the second saw operation.
A still further object of the invention is to provide an apparatus which can easily determine the contour of a log in three dimensions.
These objects are achieved by directing beams from a series of line projecting lasers onto a log which is to be cut. A camera is positioned in opposition to the log to detect the position of the laser beam lines on the log. The position of the headblocks is also detected. A three dimensional contour of the log is determined by the position and straightness of the laser lines as a function of headblock position.
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James C. Green, Pres., 3-D Log Scanning and Optimization, Oct. 20, 1993, 16 pp.
Hughes Michael G.
Rousseau William A.
Gordon Paul P.
Silvatech Corporation
Sughrue Mion Zinn Macpeak & Seas, PLLC
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