Abstract:
Provided are a system and method for cutting boards into two board pieces, even ending one of the board pieces at a first side while travelling transversely on a conveyor and even ending the other board piece at a second side of the conveyor.

Description:
This application claims priority to U.S. provisional patent application No. 61/684,529, filed 17 Aug. 2012, the complete disclosure of which is incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     The invention relates to a system and method for cutting boards into two board pieces, even ending one of the board pieces at a first side while travelling transversely on a conveyor and even ending the other board piece at a second side of the conveyor. 
     BACKGROUND OF THE INVENTION 
     It is common for lumber to be cut into two pieces transversely, i.e. 2×4×20′ cut into 2−2×4×10′, to improve the overall grade and therefore value. An example is a board that has knots or other defects in one end, but not the other end. Cutting into two shorter boards keeps the defects in one segment from devaluing the other segment. 
     Typically, lumber cut in this manner in automated lumber handling systems require one part to be diverted to another system or one of the two boards to be relocated to an empty lug for handing. A common method to relocate is for the control system to recognize the need and to interrupt the feeding process to allow an empty lug to be developed right behind the lug containing the board needing to be relocated and arms used to lift one portion over the lugs and into the empty lug space. The creation of the empty lug amounts to loss of opportunity and the related lost production. There have been methods devised in an attempt to solve this problem, that require each board to be acted upon individually, causing complexity in controls and mechanical systems, limiting the speed possible and increasing the cost. 
     An example of prior art cutting systems shown in U.S. Pat. No. 6,892,614 (Olsen), issued, 17 May 2005, and U.S. Published Patent Application No. 2003/0183052 (Olsen), published 2 Oct. 2003, the complete disclosures of which are incorporated herein by reference. 
     SUMMARY OF THE INVENTION 
     An objective of the invention is to provide an efficient system and method in which the two portions of the cut in two board remains on their original now shared lug space, but each piece is even ended so that they can be sorted or other manufacturing process performed independently. Due to length variation of the boards, it is required that the boards be even ended to an index point to allow automated handing and processing. 
     Provided is a double even ending board cutting system comprising:
         a conveyor comprising an endless chain loop having lugs constructed to convey un-cut boards and boards cut into first and second board pieces transversely, the first conveyor having a first side index line and a second side index line;   a first section of the conveyor comprising a plurality of first powered rollers constructed to move first board pieces travelling on the conveyor to the first side index line to even end first board pieces at the first side index line traveling through the first section;   a second section of the conveyor comprising a plurality of second powered rollers constructed to move second board pieces travelling on the conveyor to the second side index line to even end second board pieces at the second side index;   and   an overhead hold back constructed to hold the second board pieces in place on the traveling conveyor while the first board pieces are being moved by the first powered rollers and to hold the first board pieces in place while the second board pieces are being moved by the second powered rollers.       

     Also provided is a method of double even ending boards comprising:
         conveying a first board piece and a second board piece transversely on a conveyor comprising an endless chain loop having lugs, the first conveyor having a first side index line and a second side index line;   using a plurality of first powered rollers located in a first section of the conveyor to move the first board piece to the first side index line to even end the first board piece, using an overhead hold back to hold the second board piece and any uncut boards in place while the first board piece is being moved; and   using a plurality of second powered rollers located in a second section of the conveyor to move the second board piece to the second side index line to even end the second board piece, using the overhead hold back to hold the first board piece in place while the second board piece and any uncut boards are being moved.       

    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates a side view of section A of the system. 
         FIG. 2  illustrates a side view of section B of the system. 
         FIG. 3  illustrates a side view of section C of the system. 
         FIG. 4  illustrates a top view of the system. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     The system and method to even end each end of a cut in two board to opposite even ends of the system without needing electronic controls or complicated mechanical systems will be described with reference to the attached non-limiting Figures. 
     The system comprises a conveyor  2  having a plurality of lugged chains  4  with lugs  6  attached driven in such a way as to convey boards  20  transversely. The system further comprises a cutter  8  constructed to cut the boards  20  into first board pieces  22  and second board pieces  24 . The conveyer  2  has a first index line  30  on a first side, such as a far side, and a second index line  34  on a second side, such as a near side. 
     A first section B, shown in  FIG. 2 , of the conveyor comprises a series of first powered rollers  32  to propel the first board piece  22  to the first index  30  while the piece  22  is traveling on the chains  4  over the rollers  32 . These rollers  32  are directed to even end the first board pieces  22  to the first side index line  30 . An overhead hold back device  40  is constructed to hold the second board pieces  24  and uncut boards  20  in place on the chains  4  (i.e. the second board pieces  24  and uncut boards  20  continue to travel with the chains  4  but are not moved in relation to the sides of the conveyor  2 ) while the first board pieces  22  are even ended at the first index line  30  by the first rollers  32 . 
     The hold back device  40  employs, for example, a rigid support member  42  running in the direct of lumber flow with a flexible portion  44  attached. This flexible portion  44  is angled to and in contact with the second board pieces  24  and uncut boards  20  to prevent them from moving in the direction to the far end index line  30  but allowing them to be propelled by the chains  4  in the chain flow direction. This flexible member  44  can be as long as the rollers  32  and in contact with a multiple of boards  24  and  20  of varying sizes effectively preventing them from changing their location in a side-to-side direction. Exiting this first section B far end cut in two boards  22  have been positioned to the first index line  30  and all others (un cut boards  20  and near end cut in two boards  24 ) have not moved from their original location relative to the sides of the conveyor  2 . 
     It is envisioned that the system can work without the flexible member  44  being angled. Also, an opposing member underneath the lumber powered or unpowered may be used to improve the performance of the hold back device  40 . 
     A second section C, shown in  FIG. 3 , of the conveyor  2  is much like the first section B, with a plurality of second rollers  36  operating in the opposite direction as the first rollers  32 , i.e. toward the second index line  34 . In the second section C, the second board pieces  24  and uncut boards  20  are moved by the second rollers  36  towards the second index line  34  to even end the second board pieces  24  at the second index line  34 . The overhead hold back device  40  is constructed to hold the first board pieces  22  in place on the chains  4  while the second board pieces  24  and uncut board pieces  20  are even ended at the second index line  34  by the second rollers  36 . 
     In this embodiment, the rollers  32  and  36  remain running as long as the chain  4  is running, thus not requiring a control system. However, a control system can be used if desired to control the rollers  32  and  36  and chain  4 . 
     While the invention has been described with reference to particular embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the scope of the invention. Therefore, it is intended that the invention not be limited to the particular embodiments disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope and spirit of the appended claims.