Automatic floor board classification method and system therefor

A method and a system for classifying a plurality of random length boards of random grade, using a conveyer provided with reading units to read both the length and the grade of each board at a first end of said conveyer; a processor, receiving length and grade data from the reading units; calculating combinations of board lengths and grades and selecting a preferred combination of boards from the combinations; and a distribution section, located at a second end of the conveyer, and operated by the processor according to the preferred combination; the processor being fed with a large number of identified boards, from which to calculate the combinations of board lengths and grades, before they reach the distribution section.

FIELD OF THE INVENTION

The present invention relates to wood grading. More specifically, the present invention is concerned with automatic floorboard classification and bundling method and system therefor.

BACKGROUND OF THE INVENTION

In a conventional wood floor manufacturing line, boards processed by a tenoner are conveyed to manual sorting stations where operators form bundles, by arranging the boards in rows according to their grade. The floorboards to sort typically have a length in a range between 10 and 84 inches, in as many grades as determined by the producer according to the species.

Since bundles of floorboards are sold in units representing a surface (square foot), efforts are made to at least ensure a target surface in each bundle. However, since only the target surface is billed, it is important not to oversize the bundle. For that purpose, flexibility of the bundling system and method is needed.

U.S. Pat. No. 6,510,364 for example describes a method for selecting random length boards for nesting in a single row of predetermined lengths, including first arranging the boards on an accumulating rack, then conveying the boards to channels in an adjacent storage rack. As the boards are conveyed from the accumulating rack to the storage rack, their length is determined for transmission to a central processor. The processor calculates combinations of board lengths in the storage rack, which will form a single stock row having a combined board length within a predetermined target range. The processor then selects a preferred combination of boards from the possible combinations, and activates gates in the channels to drop the boards to a conveyor and move the selected boards to a stock row accumulating location. The processor then activates gates on the accumulating rack tracks to convey additional boards to empty channels in the storage rack, and repeats the process.

There is still in the art a need for an automatic floorboard classification method and a system therefor.

SUMMARY OF THE INVENTION

More specifically, there is provided a system for classifying a plurality of random length boards of random grade, comprising a conveyer provided with reading units to read both the length and the grade of each board at a first end of the conveyer; a processor receiving length and grade data from the reading units, calculating combinations of board lengths and grades and selecting a preferred combination of boards from the combinations; and a distribution section, located at a second end of the conveyer, and operated by the processor according to the preferred combination, wherein the processor is fed with a large number of identified boards, from which to calculate the combinations of board lengths and grades, before they reach the distribution section.

There is further provided a method of classifying a plurality of random length boards of random grade from a finishing station to a distribution station, comprising the steps of a) determining the grade of each board; b) determining the length of each board; c) conveying the boards from the finishing station to the distribution unit on a conveyer, reading both the grade and the length of each board at a first end of the conveyer for calculating combinations of board lengths and grades and selecting a preferred combination; and d) operating the distribution unit, at a second end of the conveyer, according to the preferred combination.

Other objects, advantages and features of the present invention will become more apparent upon reading of the following non-restrictive description of embodiments thereof, given by way of example only with reference to the accompanying drawings.

DESCRIPTION OF EMBODIMENTS OF THE INVENTION

As shown in the layout ofFIG. 1, a classification system according to an embodiment of an aspect of the present invention generally comprises a reading station14and a distribution station26.

The distribution station26typically comprises a vacuum belt feeder18and row-ordering conveyers20.

A central processor24communicates with the reading station14and the distribution station26to automatically operate the system. The processor calculates combinations of board lengths and grades to form rows, for example, of boards of a given grade to yield a combined board length, and selects a preferred combination of boards from the possible combinations.

FIG. 2is a close up view of the region of the reading station14at the output of a finishing machine, such as a tenoning machine10.

When they exit the tenoning machine10, the boards22-1to22-8as illustrated inFIG. 2for example, are aligned, a small extremity thereof facing an operator13as they are conveyed transversally by the output conveyer12of the tenoning machine10(see arrow A).

The operator13is then able to sort out the boards22by their grade, by pulling out the boards of a grade different from a target grade along a distance (b). In the illustration ofFIG. 2, the boards22-4,22-5and22-8have thus been sorted out.

Before leaving the output conveyer12of the tenoning machine10, the boards pass before sensors15and17, the sensor15being distances away from the sensor17so as to detect only the boards that have been pulled out by the operator over the distance (b), such as, here for example, boards22-4,22-5and22-8. Boards activating only the sensor17are identified as of the target grade, whereas boards that both sensors15and17detect correspond to those boards that have been previously pulled out by the operator13, here for example, boards22-4,22-5and22-8, and are therefore identified as belonging to a distinct grade.

Obviously, the number of sensors may be increased, corresponding to an associated number of distances over which the boards are pulled out by the operator, to sort out a corresponding number of different grades.

Alternatively, a scanner27is used instead of the operator13to determine the grade of the boards22. In this case, a code, such as a bar code for example, containing the grade information is affixed on each board after scanning. The same scanner27, located before the tenoning machine10, typically used to locate defaults to be corrected by the tenoning machine10, may be used to determine the grade of the boards, before they enter the tenoning machine10, for example.

Then the boards are passed over to the reading station14.

The reading station14is typically a conveyer, conveying the boards longitudinally (arrow B,FIG. 2). It comprises sensors19, such as a length-measuring sensor that reads each board along a length thereof. The sensors19allow recording the length of each board, as well in known in the art

In the case when the grade was identified by an operator as described hereinabove, the grade may be recorded as soon as the location of the sensors15and17. In the case when the grade was read using a scanner, as described hereinbefore, a code reader21may be used from the location of this scanner on, to read the code containing the grade information as the boards are conveyed on the conveyer14towards the distribution station26(arrow B).

In any case, at this point, each board is fully identified, both by its grade and length, and the data are transmitted to the central processor24.

The boards may be fed from the reading station14to the vacuum belt feeder18of the distribution station26by an ejection station16.

As best seen in the close-up views ofFIG. 3, as they reach the ejection station16, the boards are taken over transversally on endless chains with cleats30(seeFIG. 3b). More precisely, a first series of cleats32receive the boards as they come and transmit them over to a second series of cleats34, which is synchronized with suction heads36of the vacuum belt feeder18, in a continuous flow.

The central processor24, already knowing the length and the grade of each incoming board at this point, may identify the suction head36collecting a given board22so as to monitor its displacement and make the suction head drop the board in the adequate one of the row-ordering conveyers20ofFIG. 1.

The vacuum belt feeder18may be a synchronised vacuum belt feeder as described in copending patent application U.S. Ser. No. 11/271,547, incorporated therein by reference. It is used to distribute the boards to one of the plurality of row ordering conveyers20.

The row-ordering conveyers20typically distribute the boards into rows.

A method for classification of wood boards, of constant or variable length, of a same grade for any given species of wood, according to an embodiment of a further aspect of the present invention will now be described in relation to the flowchart ofFIG. 4.

The boards to sort typically have a length in a range between 10 and 84 inches, although they made have any length, in as many grades as determined by the producer according to the wood species.

The method comprises recording and processing both the length and the grade of the boards at an early stage of the process.

Provided a plurality of random length boards of random grade, their grade is determined (step210), and, after exiting the finishing machine that fixes their length, the length of each board is determined (step220); as the boards are conveyed from the finishing machine to a distribution station both the length and the grade of each conveyed board is recorded and transmitted to a processor (step230) for calculating combinations of board lengths and grades and selecting a preferred combination of boards from the combinations (step240); and the distribution station is then operated according to the preferred combination (Step250).

Once cut out and milled, the boards exit tenoning machine10through an output conveyer12.

Step210may be performed at a number of stages, depending of the installation and available means. For example, their grade may be determined by the same scanner used to determine the remaining defaults to be dealt with by the finishing machine, before entering the finishing machine10as described hereinbefore, and each board gets a code containing the grade information on a side thereof. Alternatively, an operator sorts out the boards by grade as they exit the finishing machine10, as described hereinabove for example.

Step220may be performed as soon as the length of the boards is definite, i.e. generally from the exit of the finishing machine on. It may be convenient to have the length of each board measured as they are being conveyed to the distribution station26.

For example, the length may be detected for each conveyed board as they are conveyed on a conveyer of the reading unit14, equipped with length sensors as well known in the art.

In any case, step230is performed early as the boards are conveyed to the distribution station26.

They are finally they are fed to the vacuum belt feeder18according to both the length and grade thereof (step250).

The boards are ejected transversally so as to be received centrally (along a length thereof) on suction heads of the vacuum belt feeder18, for increase stability, as they are conveyed in essentially horizontal equilibrium. The vacuum belt feeder18thus takes over the boards, for a continuous and fast distribution thereof to row ordering conveyers20. More than 300 linear feet of wood may be processed per minute by this type of vacuum belt feeder18, the boards never being stopped on their way to the row-ordering conveyers20.

Since the length and the grade are both determined at an early stage of the classification method, the central processor is fed with a large number of identified boards, from which to calculate combinations of board lengths and grades, well before they reach the row-ordering conveyers20. The combination output of the processor is thus highly improved, resulting in correspondingly more effective solutions to arrange boards together into rows corresponding to bundles matching very closely a target surface. As a result, non-billable surface is reduced in each bundle.

Once the rows are completed, they are picked up by a vacuum system of the row-ordering conveyers20and conveyed to stacking and packaging stations22for example, where bundles of typically about 20 square feet, or any adequate surface are formed and secured.

People in the art will appreciate that the grade and the length of each board are recorded for transmission to the processor as early as possible. The length may be determined and recorded from the point where the length of the board is fixed, generally from the time they exit the tenoning machine on, using length determining techniques and tools such as optical motion sensors as known in the art. The grade may be determined any time before or after the tenoning machine, manually or with a scanner as described hereinabove. Both the length and the grade information are gathered and sent to the processor at an early stage, for an improved combination output and consequently, an optimized classification and bundling of the boards.

In the example described hereinabove, for example, there is a distance of about 80 feet between the tenoning machine and the ejection unit of the distribution station, i.e. roughly the length of the conveyor14, for a distance of 15 feet between the ejection unit and the first row-ordering conveyer. There are in average 25 boards on the conveyor14, and about 30 of them on their way to the first row-ordering conveyer, since at this point, they are conveyed side to side. Therefore, there are about 50 boards identified at each time for calculating combinations.

Obviously the precision of the present invention varies with the distribution of the lengths of the boards to be classified. However, the classification is optimized.

As people in the art will appreciate, the present method allows a continuous flow of boards for an optimized sorting thereof in regards to both length and grade, thereby yielding optimized classification.

Although the present invention has been described hereinabove by way of embodiments thereof, it may be modified, without departing from the nature and teachings of the subject invention as defined in the appended claims.