US-12617119-B2 - Computer-assisted shingle sawing method and installation

Abstract

A computer-assisted shingle sawing method for recovery optimization using a 0-1 defect relative to the clear line, comprising the steps of taking an image of a next slab to be cut from a wood block; defining from that image, a clear line there-across; and locations of defect on that slab relative to the clear line, determining edge lines of shingles recoverable from the slab according to optimal shingle grade recovery; sawing the next slab along these edge lines, and sawing the next slab from the wood block, thereby releasing an optimum recovery of shingles from the slab. In another aspect there is provided a method for shingle recovery optimization using an optimization by inversion strategy, wherein the inclination of a parting line for cutting the next slab from the wood block is determined for optimal shingle grade recovery. There is also provided an installation for carrying out these methods.

Inventors

• Pierre Michaud

Assignees

• CLAIR INDUSTRIAL DEVELOPMENT CORPORATION LTD.

Dates

Publication Date

20260505

Application Date

20230921

Claims (4)

1. 1 . A computer-assisted shingle sawing method comprising: taking an image of a shingle to be cut from a wood block; determining from said image, an exposure line on said shingle, said exposure line defining an exposed portion of said shingle and a covered portion of said shingle; determining from said image, a location of a defect on said shingle relative to said exposure line; and if said defect is found in said exposed portion of said shingle, adjusting an inclination of said wood block prior to said shingle being cut from said wood block, to orient said shingle in a position where said defect is located in said covered portion of said shingle.
2. 2 . A computer-assisted shingle sawing method comprising: taking an image of a next shingle to be cut from a wood block; determining from said image a covered portion of said shingle and a position of a defect relative to said covered portion; determining from said image, prior to said shingle being cut from said wood block, an orientation of said shingle to position said defect in said covered portion of said shingle; and adjusting an inclination of said wood block to obtain said orientation.
3. 3 . The computer-assisted shingle sawing method as claimed in claim 2 , wherein said orientation defines a location of a thick end of said shingle relative to said defect, for obtaining a best wood recovery value of said wood block.
4. 4 . A computer-assisted shingle sawing method comprising: taking an image of a shingle to be cut from a wood block; determining from said image an exposed region and a covered region of said shingle and a position of a defect relative to said regions; determining from said image, prior to said shingle being cut from said wood block, an orientation of said wood block to position said defect in said covered region of said shingle; and adjusting an inclination of said wood block to obtain said orientation.

Description

This is a Continuation application of application Ser. No. 17/300,060, filed on Feb. 26, 2021. FIELD OF THE PRESENT INVENTION The present invention pertains to the field of shingle sawing, and more particularly, it pertains to a shingle sawing method and installation using a computer-assisted machine including machine vision and a grade selection algorithm. BACKGROUND OF THE PRESENT INVENTION The shingle sawing profession is perhaps the most demanding one in the field of forest industries. A shingle sawyer must be capable of picking up a cedar slab laid against a large vertical rotating saw without looking, and trim both sides of this slab on a nearby table saw. The trimming is done by trimming a first edge, flipping the slab over and trimming the other edge. The trimming is done while watching the main saw; periodically readjusting the cedar block on the main saw's carriage and releasing the carriage's back and forth motion for sawing another slab and repeating the motion. The trimming on the table saw is done to produce the best available width for a top-quality grade of shingles, or a best available width for a second or third grade of shingles depending on the market demand at that time. A shingle sawyer must pay attention to his work at all times. A shingle sawyer cannot let his mind wander away for a second as most people do when doing monotonous job. Therefore, the rumour is true; you can recognize a long-time shingle sawyer by counting his/her remaining fingers. It becomes more and more difficult to find workers who want to enter the profession. New generation sawyers are not as productive as their elders. Five years ago, a good shingle sawyer was producing on average 22-23 squares of shingles per eight-hour shift. A square of shingles is 100 square feet. Today, a good shingle sawyer produces on average 15-16 squares per eight-hour shift. Therefore, there is a need in the industry for robotic or computer-assisted machinery to fulfil the void left by the unavailability of workers in this field. There are, however, major difficulties to overcome in the sawing of shingles by computer-assisted machines. The grade selection standard for wood shingle requires visual acuity, a subjective interpretation of dozens of quality criteria, and a keen decision-making ability that is difficult to match by a computer. It will be appreciated that the grade-selection standards for wood shingles have not been written for interpretation by a computer. For example, some of the grade selection criteria for one grade of wood shingle are listed below. CAN/CSA 0118.2-94 (0118.2M-94) Eastern White Cedar Shingles. Extra-Grade A: Grading: This grade has a clear face which allows the following characteristics:Grain: Diagonal grain is accepted when the grain diverges or slants 1 inch or less in 4 inches of length measured from the butt.Sapwood: Accepted above the clear line, 8″ (203 mm) from the butt.Decay: Not accepted, including the butt and the exposed edges.Pin Knots: They refer to ingrown knots of 1/16″ (1.5 mm); are accepted above the clear line, 8″ (203 mm) from the butt.Edges: Shingles widening at the tip are not accepted. They must possess parallel sides, within ¼″ (6 mm)Length: Length shall not exceed ¼″ (6 mm) less than nominal length, except a minus tolerance of 1 inch below nominal length is permitted in fifteen (15%) of the running inches in the bundle, from 15″ to 15¾″ (380 to 400 mm) Feather tips shall be permitted.Shingle thickness: At time of manufacturing, shingles should be reasonably uniform in thickness. The approximative thickness of a 16″ (406 mm) shingle must follow the 5/2 rule, i.e., the thickness of the butts of 5 shingles must measure about 2″ (50 mm) plus or minus 5%.Width: The minimum width is 3″ (76 mm), with no more than 20% of the running inches (running millimetres) of the bundle consisting of shingles of 3½ in (89 mm) and less.Torn grain: Accepted on 10% of the running inches (max. 1/16″/1.5 mm long).Waves: Accepted on 10% of the running inches, when judged “abnormally visible”.Shingles that have any slight deviation from the Grade A criteria are classified in other classifications:CLEAR—Grade B:SECOND CLEAR—Grade C;CLEAR WHITE—Brown Label, orUTILITY (cull)—Grade D. These secondary grades accept some relaxations to the Grade A criteria, with added tolerable defects related to check and ring shake; wane; inclination of grain; soundness of knots; inter-grown knots; black knots; encased knots; loose knots; unsound knots; holes; bark; streaks of resin; decay; and in the relative location of knots, holes, resin, bark, or decay to the clear line of the shingle. It will be appreciated that a major portion of these criteria are determined subjectively. These criteria are not related to 1 and 0 defect determinations, as it is done by a computer. A good shingle sawyer normally does an apprenticeship as a bundle maker for a thousand hours or more to develop skills in learning shingle quality criteria. Af