Contour line scanner

A method of economically optimizing the sawing of boards from a cant having a pair of opposite broad faces defining a thickness of the cant and a pair of opposite side faces defining a width of the cant, the method comprising:

• storing current values of boards of different widths for a selected grade of lumber;
• projecting a thin line of light onto each opposite side face of a cant in a plane parallel to the width of the cant to form a pair of contour lines along the opposite side faces and thereby define a grade line on each side face at a predetermined position spaced between the broad faces of the cant corresponding to said selected grade;
• sensing the relative positions of the contour lines widthwise of the cant;
• positioning one of the cant and a first saw for sawing the cant lengthwise normal to said plane along a first sawline at a specified widthwise position inwardly adjacent a first one of the contour lines so as to saw the cant along the first sawline in accordance with the selected grade;
• determining a second sawline parallel to the first sawline at a widthwise position relative to the second one of said contour lines to maximize, in accordance with the stored values, the aggregate value of boards of the selected grade to be sawn from the cant, and
• positioning a second saw to saw the cant along the second sawline.

A method of economically optimizing the sawing of boards from a cant having a pair of opposite nonparallel side faces, the method comprising:

• storing current values of lumber of different grades, the grade being determined by a dimensional characteristic of the lumber including an amount of corner truncation and by a nondimensional characteristic of the lumber;
• storing current values of boards of different widths for a selected grade of lumber;
• grading the cant in accordance with said nondimensional characteristic to determine its grade;
• projecting a line of light onto each opposite side face of the cant in a plane parallel to the width of the cant to form a pair of contour lines along the opposite side faces;
• positioning the lines of light normally to said plane in accordance with said grade to delineate a maximum amount of corner truncation on the side faces of said cant for said grade as a function of said dimensional characteristic;
• and
• determining positions of at least two parallel sawlines spaced apart between said contour lines which will produce a maximum value of lumber from the cant, including lumber having said maximum amount of corner truncation.

Sawmill control apparatus for sensing the contours of an irregularly-shaped elongated wooden workpiece and determining an economically optimum sawline, comprising:

• beam-forming means for projecting thin coplanar sheets of light against opposite sides of the workpiece in a predetermined plane extending lengthwise of the workpiece to form a pair of contour lines defining a widthwise dimension of the workpiece and characterizing any irregularities in the workpiece in said plane;
• matrix sensor means directed normally to said plane and having a two-dimensional field of view for sensing the contour lines at a plurality of intervals along a substantial lengthwise portion of the workpiece and producing a pair of output signals corresponding to the widthwise position of the pair of contour lines at each interval;
• means responsive to the pairs of output signals at each interval for determining the widthwise positions of the contour lines and computing therefrom an optimum sawline through the workpiece normal to said plane as a function of the widthwise dimension of the workpiece defined in said predetermined plane by said contour lines;
• and
• means responsive to the computing means for positioning one of the workpiece and a saw for sawing the workpiece along said optimum sawline.