Abstract:
A lumber processor includes slowdown conveyor to transition lumber pieces from one processing device to a subsequent processing device where the movement of lumber pieces changes from lineal to lateral motion; a printer station includes a printer boom which includes a lateral translation device to move a symbol printer over the path of travel of the conveyor to allow the printer to mark pieces of lumber that are passing beneath the printer station.

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention relates to cut lumber processing and handling devices that will allow greater manufacturing efficiency and lower costs while increasing quality of the resulting products. More specifically, the present invention relates to a scanner which will operate in cooperation with a printer which will print results derived from the scanning operation on each lumber place for subsequent sorting and handling in a lumber mill.  
         BACKGROUND OF THE INVENTION  
         [0002]    In present-day in lumber mills, the practice has become common of increasing throughput speeds in order to reduce costs and to take advantage of increased processing speeds made possible by the use of operational sensors and computers. However, when new equipment is installed in a production line, it is desirable that the production speed of the original equipment not be compromised. It sometimes happens in established mills that new equipment can be operated efficiently at higher speeds than the already installed equipment so that some type of accommodation is required to minimize any reduction in the through put speed and capacity of the mill operation.  
           [0003]    A difficulty in enhancing mill production capacity is the wide variety as well as the number of defects in the lumber that are encountered. Some of these defects cannot be accurately detected by automatic sensors particularly those operating at the increased conveying speeds presently in use. As a consequence, human inspection is still required for some grades of lumber. Such human inspections can take place where the lumber path is required to turn through as much as 90° such as when the lumber is passed from a planing device to a sorting device in a mill operation. With the increasing scarcity of good grade of lumber, the types and variety of the defects in the lumber are likely to increase so that the necessity of effective scanning, electronically and by visual inspection, before sorting is correspondingly increased to assure that the final product is marketable.  
         SUMMARY OF THE INVENTION  
         [0004]    The present invention provides an arrangement for a lumber mill and a method of operation that will enable a mill operator to maintain the production capacity while taking advantage of increased grading accuracy speeds afforded by presently available defect scanning devices. In addition, a mounting arrangement for a symbol printer is provided to improve the flexibility of the printing operation relative to conveying apparatus conventionally used in lumber mills.  
           [0005]    More specifically, in presently operating mills and in other environments, it has been the practice to employ slowdown conveyors to transition lumber pieces from one processing device to a subsequent processing device and were the movement of the lumber piece changes from lineal to lateral motion. In cooperation with at least one of the slowdown conveyors where a sequential series are employed, at a printing station, a printing boom is installed which includes a lateral translation device to move a symbol printer over the path of travel of the conveyor to allow the printer to mark pieces of lumber that are passing beneath the printer station. The printer output is preferably a symbol that will enable a downstream positioned inspector to confirm the classification of the lumber piece set by the scanning device.  
           [0006]    With this arrangement control of the production speed can be maintained without diminishing the production rate of the mill. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0007]    [0007]FIG. 1 is a top plan view of a conveying set up from a scanning position to an output position;  
         [0008]    [0008]FIG. 2 is a side view in elevation of the set up of FIG. 1;  
         [0009]    [0009]FIG. 3 is an end view taken along lines  3 - 3  of FIG. 2; and  
         [0010]    [0010]FIG. 4 is a detail view taken along lines  4 - 4  of FIG. 3. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0011]    Referring to the drawings where like numerals designate corresponding parts throughout the several views, there is shown in FIG. 1 a conveying arrangement  10  which includes a manning station  12 , a first slow down conveyor  14  downstream of the station  12  and a second slow down conveyor  16  downstream of the first conveyor  12 . The flow of pieces of lumber through the arrangement is indicated by the arrow  18  in the figures. Downstream of the conveyor  16  is lateral conveyor  20  which moves in the direction of arrow  22  to an inspection station  24  from which the boards are passed to feeder  26  which spaces the boards out on conveyor  30  to allow reading by a reader  32  of the printed material placed at station  16  as described below.  
         [0012]    The scanner  12  includes a high speed belt conveyor  34  which will receive a piece of lumber  36  typically from a planer machine upstream of arrangement  10  and rapidly move the piece  36  under a defect scanner  12 . One example of such a scanning operation involves the use of a laser and photocells with the laser used to illuminate the board and the photocells measuring the reflected light. Dark spots indicate the presence of a knot or other defect which warrants separation of the piece so marked from blemish free pieces of lumber. Other defects may also be detected depending on the type of lumber being handled and the market for which the lumber is intended. The use of several different types of defect scanners is also feasible and the subsequent scanners may be located adjacent the scanner  12  around the conveyor  34 . Since these types of scanners operate at high speeds, such as on the order 2000 ft/minute for board throughput, and the downstream printers presently available operate at much slower speeds, one or more slow down conveyors  14  and  16  which are typically used in mills such as where the production line turns though an angle, are used in combination with the printing operation. Typically, the printing equipment can operate on a piece of lumber moving at about 1000 ft/minute. To achieve this magnitude of reduced speed, the conveyors  14  and  16  which are usually belt conveyors as shown receive the piece of lumber at an angle to the direction of transport from the exit end of conveyor  34 . The width of each conveyor  14 ,  16  determines the number of pieces of lumber that can be accommodated as each piece is moved toward the printing station  38 .  
         [0013]    Since the slow down conveyors, to be effective, must spread out the pieces of lumber  36  laterally while still effecting longitudinal movement as shown on conveyors  14  and  16 , the present invention provides at the printing station  38  an adjustment capability for a printing head. In one form, a pair of support arms  40  is attached to the conveyor chassis. In an alternate form, the arms  40  may be mounted on the floor. At its upper end, the arms  40  pivotally support a pair of booms shown at  42  for adjustment about a horizontal axis  44 . At its free end, the booms  42  support a pair of vertically spaced guide rods  46  on which is slidably mounted a for a printing head  48 . In operation, the printing head  48  is preferably an ink jet printer and is therefore spaced a small distance from the surface to be printed and the thickness of the boards will thus determine the position of the booms above the conveyor. Once the booms are positioned for a run, further adjustment is unnecessary. Also carried on the free end of the booms is a hydraulic or air piston and cylinder  53  for positioning the printing head in operation as described below. It is preferred that upstream of the printing head  48 , a roller  50  be positioned to engage the upper surfaces of any bowed or twisted boards as they travel underneath the printing head  48  in order to flatten and stabilize the individual boards to improve the printing quality. To accommodate irregular boards and to avoid damage to the printer head, the booms may be capable of upward pivoting about axis  44  if an object impacts the roller  50  and the booms  42  under their own weight will then return to the selected position above the conveyor  16  after such an impact.  
         [0014]    A support platform or rod  55  extends between the ends of the booms  42  and on the upper side  52  of the platform  55  is supported a board position sensor such as a photocell. The photocell output will be sent to a computer such as at  58  which will then control the actuation of the piston and cylinder  53  to position the printing head directly over a plow of lumber  36  moving on conveyer  16  and then actuate the printing head to print a symbol on a piece of lumber. After printing one board, the computer will then move the printing head  48  laterally by actuation of the piston and cylinder  53  over an adjacent piece of lumber and print the appropriate indicia thereon. By way of example, in a mill operation, it is preferable to print a symbol as noted above that is representative of the quality or other characteristic of the piece of lumber as determined by the upstream defect scanner  12  the output of which is also fed to the computer and stored there at least until the inspected place of lumber is adjacent the printing head  48 . By appropriate software control, the scanned information symbol will be marked on the correct piece of lumber since the sequence of movement and timing will not vary between the scanner  12  and printing position  38  under normal operating conditions.  
         [0015]    From the printing position  38 , each piece will be pad to the landing table  20  where movement is shifted laterally in the direction of arrow  22  to a manual inspection position  24 . As is the practice, a worker may make sure each piece is graded properly and marked by the printer before the piece is passed to the board feeder  28  and symbol reader  32  after which sorting takes place and any subsequent milling operation.  
         [0016]    As will be apparent to those skilled in this field, various modifications to the foregoing process and apparatus are possible and it will be understood that such modifications are within the scope of this invention.