Method for Grading and Measuring Lumber and a Trimming Device for Performing Said Method

The present invention relates to a method for grading and measuring lumber, preferably boards and planks, during their transport through a trimming device. The invention also relates to a trimming device for performing said method.

In grading and measuring pieces of lumber during their transport through a trimming device it is previously known first to cut the root ends off the pieces of lumber in order to adjust these ends. Thereafter the lumber is transported by a transversely directed roller conveyor to a side stop, and thereafter to another transversely directed roller conveyor combined with measurement flaps. A grader is inspecting the lumber and decides where the pieces are to be cut. Depending thereon he also adjusts one of a number of end stops arranged in combination with a third transversely directed roller conveyor, which feeds the root ends of the lumber pieces against the chosen end stop whereafter top ends cuts are made. When measured from the root end surfaces the lumber will have a length which is the same as a multiple of a length module unit, which consequently does not happen until the lumber has passed to top end cutter blade arranged as the last process station. Every piece will be fed three times in the transverse direction of the trimming device.

It is an object of the present invention to provide a method by which it is possible to let only those pieces of lumber, which at the grading are found to be defect or of an inferior quality, be fed three times in the transverse direction of the trimming device while all the rest of the lumber can pass through the trimming device only with two transverse feedings which will make the work procedure simplified and faster. Furthermore, the method according to the invention makes it possible, when there are defects, inferior quality etc., to make the determination or measurement of the length of a piece of lumber, the top of which is to be cut, from the top surface of the lumber.

This is accomplished by a method for grading and measuring lumber, preferably boards and planks, during their transport through a trimming device, in which the lumber is cut at the root and top ends, said method being characterized by the fact, that the lumber, such as a piece of board, immediately after the root end cut by top cutting by less than one length module unit, is given a length that is exactly one multiple of the length module unit, the piece of board thereafter being transported to a turning device, where all sides of the board are inspected, which is known per se, the piece of board thereafter either being transported out of the trimming device, or, if additional top end cutting is required, being transported with its top end surface against a locating stop, which is chosen with regard to the required length of the top end cut and which is set into an active position, said locating stop being brought to follow the top end surface under continuous contact for axial guidance of the piece of board, said piece of board thereafter being transported to and cut by a cutting device, such as a cutter blade, said cutting device being arranged in a vertical plane at a distance of one or several length module units from the stopping plane of the guiding locating stop.

A trimming device for performing said method and comprising a transverse conveyor, a root end cutter blade, top end cutter blades, transversely directed roller conveyors, measurement flaps, end stops and a turning device is characterized by the fact that said trimming device in its transport direction is provided with in turn a transversely directed roller conveyor located immediately before the root end cutter blade, which is located at one side of the transverse conveyor, a stop located in the transport direction of said transversely directed roller conveyor at the other side of said transverse conveyor, a line of measurement flaps, said line extending transversly across said transverse conveyor, said flaps being swingable upwards and downwards relative to the transport plane of said transverse conveyor and spaced by a distance of one length module unit, said said flaps being provided with electric switch means, a transversely directed roller conveyor arranged in combination with said measurement flaps and having its transport direction away from said stop, a top end cutter blade located at the same side as said stop, the plane of said top end cutter blade being parallel to and at a distance less than one length module unit from the plane of said stop in the transverse direction of the plane, a turning device, adjacent to said turning device a line of measurement flaps which are swingable upwards and downwards, said flaps being spaced by a distance of one length module unit, a transversely directed additional roller conveyor in the transport direction of which and outside of said transverse conveyor a line of locating stops are located, that locating stop which is most adjacent to said transverse conveyor lying in the same plane as said top end cutter blade, said locating stops being spaced by a distance of one length module unit and each locating stop being moveable in the longitudinal direction of said transverse conveyor and provided with means which can be swung upwards and downwards and brought into or out of an active stopping position for a piece of board, and a top end cutter blade located substantially in the same plane as the locating stop which is located most adjacent said transverse conveyor.

The method according to the invention and the trimming device for performing said method will be closer explained below in connection with a description of an embodiment of the invention shown in the attached drawing.

FIG. 1 shows schematically a side view of a trimming device according to the invention, in which the frame supporting the movable parts is omitted for the sake of clarity.

FIG. 2 shows a plane view of the trimming device in which the supporting frame is omitted.

The trimming device according to the invention comprises a transverse conveyor which is formed by a number of endless chains 1 only shown partly and which supports suitably spaced dogs 2 of which only a few are illustrated to the left in the figures. The driving direction of the transverse conveyor is illustrated by the arrow 3 in the centre of FIG. 2.

The trimming device is provided with the following means as seen in the driving direction. A root end cutter blade 4 is provided at the left side of the transverse conveyor as seen in the driving direction. A transversely directed roller conveyor formed by rollers 5 has a conveying direction indicated by the arrow 6. The upper surfaces of the rollers 5 are located at a somewhat higher level than the chains 1. A stop 7 is adjustably arranged in line with said roller conveyor 5 and somewhat outside of the right side of the transverse conveyor. A number of measurement flaps 8 are journalled on a shaft 9 in such a way that they can be individually swung upwards from the position shown in FIG. 1. The right sides of the measurement flaps 8 as seen in the driving direction of the conveyor are the sides for stopping and engagement, and the distance between the sides is one length module unit, which can be for example 300mm. At each measurement flap 8 an electric switch means 10 is provided for a purpose which will be closer explained below. In combination with the line of measurement flaps 8 a transversely directed roller conveyor formed by rollers 11 is provided with a driving direction indicated by the arrow 12. A top end cutter blade 13 is provided parallel to said stop 7. An extension line from the cutter blade 13 to the stop 7 will have the length a, which is less than one length module unit, said line being perpendiculary broken as the cutter blade 13 and the stop 7 are not in the same vertical plane. The distance from said top end cutter blade 13 to each measurement flap 8 is a multiple of the length module unit. A device for turning the pieces of lumber around their own longitudinal axis is only schematically illustrated with the reference number 14, said device being driven preferably at the same pace as the transverse conveyor 1. The turning device 14 can preferably be of the construction described in U.S. Pat. No. 3,759,384. At the turning device 14 the place of a grader 15 is schematically shown. A number of measurement flaps 16 are located having their longitudinal direction aligned with the measurement flaps 8. A further top end cutter blade 17 is provided in the same vertical plane as the top end cutter blade 13. A further turning device 18 is provided of the same kind as the first mentioned turning device 14. A grader has the reference number 19. Measurement flaps 20 are provided in line with said measurement flaps 16. Still another top end cutter blade 21 is located in the same vertical plane as said top end cutter blades 13 and 17. Outside at each top end cutter bade a collector 22,23,24 is provided for cut off pieces.

Ahead of the top end cutter blade 21 as seen in the transport direction a roller conveyor formed by rollers 25 is provided with a transport direction indicated by the arrow 26. In the driving direction of the roller conveyor and outside on the right side of the transverse conveyor displaceable locating stops 27a-e are provided, said stops having means which are swingable upwards and downwards. The locating stops 27a-e are spaced by a distance which is equal to one length module unit. In the same plane as the locating stop 27a, which is situated most adjacent the transverse conveyor, a top end cutter blade 28 is arranged.

Grading and measuring of pieces of lumber is made in the following way in the trimming device described above. Lumber, preferably boards, arrive to the left end of the trimming device as seen in the figures. Here the root ends are inspected and cut when required by the transverse conveyor 1, which preferably is in continuous action, feeding the piece of board by the dogs 2 to the root end cutter blade 4. During the continued transport of the piece of board B it will arrive to the roller conveyor 5 and be fed laterally in the longitudinal direction of the board against the stop 7. Under guidance against the stop 7 it will come into contact with and lift up a number of measurement flaps 8, whereafter the roller conveyor 11 will move the piece of board in the direction indicated by the arrow 12, so that the root end of the piece of board will come into abutment with the nearest not lifted measurement flap 8. After guidance against said not lifted measurement flap the top end of the piece of board will be cut by the top end cutter blade 13. The piece of board will now have a length which is equal to a multiple of the length module unit, that is the piece of board has a length which is a number of times preferably 300mm, as each measurement flap 8 has a distance to the top end cutter blade 13 which is a multiple of the length module unit as described above. The lifted measurement flaps 8 will bring their respective electric switch means 10 to a closed state, whereby impulses are fed stepwise to a suitable signal storing device or a memory provided at each respective grader 15, 19. The piece of board is transported to the turning device 14, where it will be turned around its own longitudinal axis and inspected on all sides by the grader 15.

If the piece of board is without defects the grader 15 will give an electric impulse to lift the swingable means of the locating stop 27a. Hereby the drive force of the roller conveyor 25 on the piece of board will be counteracted and the piece of board will be transported away by the transverse conveyor without further treatment.

If the piece of board must be cut at the top end due to defects or to raise the quality thereof, the grader 15 can now by pressing certain buttons cut off the desired lengths. Hereby an impulse is given to swing up of the means of a locating stop, for example 27b if two length module units are to be cut away, so that the piece of board, when arrived on the roller conveyor 25, will be fed until its top end will abut the lifted means of the locating stop 27b, and after that said means will guide the top end until the piece of board will reach the top end cutter blade 28 and the top end will be cut away.

However if the grader finds that a greater length, for example two length module units more than what is possible by setting the outermost locating stop 27e, must be cut, the grader 15 will pull the piece of board towards himself, so that the root end in this case will move past two measurement flaps 16 towards the grader and under guidance of the root end on that measurement flap which has swung down closest to the root end surface the grader can make a cut by the top end cutter blade 17. The additional required cut is made by setting one of the locating stops 27b-e and by the top end cutter blade 28. The cut by the top end cutter blade 28 can not be more than five length module units as a rule, and if a longer cut is required, the grader can pull the end of the piece of board and make a preliminary cut by the top end cutter blade 17.

In the shown example of embodiment the graders 15 and 19 have the same function and the same equipment and each of them inspects every other piece of board. There may also be for example three graders, each of which will inspect every third piece of board.

After the cutting of the top ends by one or several top end cutter blades the lumber will pass marking apparatus (not shown) which are situated ahead of the top end cutter blade 28 as seen in the transport direction, and to a next transverse conveyor or a lumber collecting device.

The following advantages are obtained by the method and the device according to the invention. Immediately after the root end cut a top end cut is made which is smaller than one length module unit, and will give the piece of lumber a length of exactly one multiple of a length module unit. As a normal top end cut, especially in thick lumber, in most cases is shorter than one length module unit, only this top end cut will be necessary, whereafter the lumber can pass through the whole trimming device without any lateral displacements. The first top end cut which gives the lumber a length of a multiple of the length module unit, makes is possible thereafter to adjust the lumber directly from the top end surfaces of the lumber when additional cuts are to be made. The top end surfaces will thus be used as O-surfaces at the measurement. All top end cutter blades are located in the same plane, which facilitates the mounting and location thereof and of the measurement flaps and locating stops, the later means depending on the top end cutter blades as regards location. The positioning of the locating stops outside of the transverse conveyor gives a freer choice of construction and makes them easier to mount, compared to if they were positioned in the transverse conveyor in the usual manner. In the embodiment described above a continuous central line is produced for the device independently of how long the top end cuts are. Consequently the device according to the invention requires a house, which need not be as broad as the houses that are required by devices previously known.

The device according to the invention can be modified within the scope of the invention as regards details. Other saw means than cutter blades can be used, for example, and the length module unit can be any length unit or part thereof. The measurement flaps can be arranged to be pressed down instead of lifted by passing lumber. The locating stops can be so constructed, that they can be set into an active position dierctly by the grader.