Abstract:
Provided is a printer for printing stamps on boards and a method of printing stamps on boards. The printer is capable of printing multiple types of stamps simultaneously on boards.

Description:
[0001]    This application claims priority to U.S. Provisional Application Ser. No. 61/245,724, filed 25 Sep. 2009, the complete disclosure of which is incorporated herein by reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The invention relates to printers and methods of applying stamps to boards. 
       BACKGROUND OF THE INVENTION 
       [0003]    The production of lumber involves the application of a stamp on a planed board that will remain with the board until it reaches the end user. These stamps primarily show the grade and sometimes other attributes of each piece of lumber. There are various sanctioning organizations that insure the quality and integrity of the various grades of lumber produced. These sanctioning organization control the issuing of stamps and their use. In addition to grade identification, stamps can be used to identify moisture content and heat treatment (for pest pasteurization) which is generally required on exported products. 
         [0004]    For example, with southern yellow pine (SYP), most of the stamps are controlled or governed by SPIB http:www.spib.org/, which is an organization that sets and inspects the rules for each lumber grade. The stamp typically includes the grade mark, which identifies the grade of the board, and an identification indicating the SPIB “member” that manufactured the lumber. Generally, the board is only stamped in one location. However, recent market changes have required additional stamp locations along the lengthwise face of the board. 
         [0005]    HT (heat treated for pest pasteurization) stamps usually are required to be applied to any wood packaging materials of any length being exported. Many manufacturers export two foot blocks that have been trimmed from the longer lengths of lumber to remove defects. Each two foot block must be marked with the HT stamp. The HT stamp cannot have a grade. The HT must state KD 19 HT. The U.S. Department of Agriculture Animal &amp; Plant Health Inspection Service (APHIS) has entered into a Memorandum of Understanding with the Southern Pine Inspection Bureau (SPIB). The overall direction and control of the cooperative program is to be maintained by APHIS. The program provides the necessary documentation that kiln dried southern pine lumber exported to foreign countries has reached a critical temperature at the core to eradicate the “Pinewood Nematode” and its vectors (56° C./133° F. for 30 minutes). The HT mark is not limited to yellow pine, and is also used for other lumber types. 
         [0006]    Mechanical printers, generally known as “grade printers,” have been widely used in planer mill applications many years, stamping the grade on each individual piece of lumber using rubber stamps. The rubber stamps are typically located on rotating wheels with only one stamp being located on each wheel. The appropriate arm is lowered with a cylinder when the corresponding piece of lumber transverses beneath the rotating wheel. The wheel must travel the same lineal speed as the lumber to avoid smearing the stamp on the lumber. Presently, the wheels are driven by roller chains from the head shaft of the lugged conveyor that the boards are traversing on, i.e. the wheels are mechanically timed with the conveyor by the chains. 
         [0007]    The lumber is generally transported on lugs, with one board per lug, transversely through a mill. Grade printers are located downstream of a board trimmer to apply a stamp to each board. For example, a lumber grader might call for grade #2-8′ on a near end of a board and grade #3-10′ on a far end of the board. When this happens, the trimmer will cut an eighteen foot board in two pieces at approximately an eight foot position. As these two pieces come out of the trimmer, the far end piece will be picked up and “jumped” into the empty lug behind it. Once these different grade boards are on different lugs, they can be stamped with the appropriate gradestamps. 
         [0008]    In addition, the stamps must also be timed to land, preferably centered, on the width of the board. Thus, for different width boards, such as 4, 6, 8, 10 and 12 inch boards, the stamp might not be located in the same position on a 4 inch wide board as on a 12 inch wide board. The timing is generally done mechanically, either with adjustable sprocket assemblies or an on-the-fly mechanical adjustment requiring a series of sprockets in a cross-shaped pattern. 
         [0009]    Many mills desire to stock longer package lengths, such as 16, 18 and 20 foot lengths, with the ability to cut the finished package into two shorter lengths. If this is done, each end of the board must contain the same grade stamp so that when they are cut in two smaller sections, each piece will include the required grade stamp. When stamps, including the grade are required on each end of the board, the conventional grade printer must span across the conveyor and similar grade stamping arms must be placed on the far end of the board. 
         [0010]    HT stamps must be placed every two feet or less on the board upstream of the trimmer to mark two foot cut-offs prior to trimming. Thus, when the stamp must include HT, two printers are required, the HT printer upstream of the trimmer and the grade printer downstream of the trimmer. Since the two foot blocks are normally dropped out to a turntable to be hand stacked, the HT stamp can be applied in the block conveyor or manually by the turntable operator. 
         [0011]    The printers are mechanically driven via roller chain drives from the main drive. Chain slack and surge cause numerous maintenance problems and increase costs. There is generally insufficient room on present printers to include 6-8 grades on each end of a board and HT marks on 2 foot centers without interfering with the lugged chains that transport the lumber on 2 foot centers. 
         [0012]    In view of the many shortcomings of present lumber printers, there is a great need for a printer that is capable of cost effectively applying stamps having different grades and other information, such as HT, manufacturer and dryness to lumber in one efficient step. 
       SUMMARY OF THE INVENTION 
       [0013]    An objective is to provide an improved printer that is capable of cost effectively applying stamps having different grades and other information, such as HT, manufacturer and dryness to lumber in one efficient step. 
         [0014]    Another objective is to provide an improved printer which is capable of apply a stamp having a first grade on one end of a board and a second stamp having a second grade at the other end of the board in one step. 
         [0015]    The above objectives and other objectives are obtained by a printer comprising:
       a support constructed and arranged such that a length of the support can mount over a width of a conveyor for conveying boards transversely to be stamped;   a drive shaft rotatably mounted to the support, the drive shaft disposed generally in the direction of the length of the support;   a plurality of arms movably connected to the drive shaft;   at least one lift mechanism constructed and arranged for lifting and lowering at least one arm;   at least one wheel rotatably mounted to at least one arm, the wheel having a plurality of stamps located around an outer surface of the wheel, and the wheel rotatably driven by rotation of the shaft;   a drive mechanism constructed and arranged for rotating the drive shaft;   a wheel position device constructed and arranged for determining a location of the stamps on the wheel; and   an ink supply mechanism constructed and arranged for applying ink to the stamps.       
 
         [0024]    The above objectives and other objectives are also obtained by a method of stamping boards using a printer comprising:
       a support constructed and arranged such that a length of the support mounts over a width of a conveyor for conveying boards transversely to be stamped;   a drive shaft rotatably mounted to the support, the drive shaft disposed in generally the direction of the length of the support;   a plurality of arms movably connected to the drive shaft;   a plurality of lift mechanisms constructed and arranged for lifting and lowering the arms;   a plurality of wheels rotatably mounted to the arms, the wheels having a plurality of stamps located around an outer surface of the wheels, and the wheels rotatably driven by rotation of the shaft;   a drive mechanism constructed and arranged for rotating the drive shaft;   a wheel position device constructed and arranged for determining a location of the stamps on the wheels; and   an ink supply mechanism constructed and arranged for applying ink to the stamps, the method comprising:   conveying a board on a conveyor under the printer so that the length of the board is substantially aligned with a length of the printer;   determining a desired stamp to be applied to the board;   rotating the shaft to rotate the wheels to a starting location for applying the desired stamp;   dropping the wheels down onto the board being conveyed for a time period sufficient for the wheels to rotate and apply the desired stamp to the board; and   lifting the wheels off of the board when the desired stamp is applied to the board and before an undesired stamp is applied.       
 
         [0038]    The objectives and other objectives are further obtained by a planer mill comprising:
       a conveyor constructed and arranged for conveying boards transversely;   a board positioning device constructed and arranged for determining a location of a board being conveyed on the conveyor;   a trimmer in communication with the conveyor constructed and arranged for cutting boards into desired lengths; and   a printer constructed and arranged for printing stamps on boards being conveyed on the conveyor, the printer comprising:   a support constructed and arranged such that a length of the support is mounted over a width of the conveyor;   a drive shaft rotatably mounted to the support, the drive shaft disposed in generally the direction of the length of the support;   a plurality of arms movably connected to the drive shaft;   at least one lift mechanism constructed and arranged for lifting and lowering at least one arm;   at least one wheel rotatably mounted to at least one arm, the wheel having   a plurality of stamps located around an outer surface of the wheel, and the wheel rotatably driven by rotation of the shaft;   a drive mechanism constructed and arranged for rotating the drive shaft;   a wheel position device constructed and arranged for determining a location of the stamps on the wheel; and   an ink supply mechanism constructed and arranged for applying ink to the stamps.       
 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0052]      FIG. 1  illustrates a view of a lumber printer; 
           [0053]      FIG. 2  illustrates a view of a lumber printer; 
           [0054]      FIG. 3  illustrates a view of a lumber printer; 
           [0055]      FIG. 4  illustrates a view of a lumber printer; 
           [0056]      FIG. 5  illustrates a view of a lumber printer; and 
           [0057]      FIG. 6  illustrates a sample stamp. 
       
    
    
     DETAILED DESCRIPTION 
       [0058]    The invention will now be explained with reference to the attached  FIGS. 1-6 .  FIGS. 1-5  illustrate a lumber printer  1  having a support  2 . The support is sized to be mounted over the width of a conveyor  40  conveying lumber in the form of boards  42  transversely. Thus, for conveyors  40  conveying boards  42  having a length of up to 24 feet, the length of the support  2  must be greater than 24 feet. 
         [0059]    A drive shaft  4  is rotatably mounted to the support  2  generally in the direction of the length of the support  2 . Preferably, the shaft  4  is split into two sections, shaft section  6  and shaft section  8 , that can rotate independently of each other. The shaft  4  is rotated by a drive mechanism  10 , such as an electric motor. Alternatively, drive mechanism  10  can be any suitable mechanism, such as hydraulic. If the shaft  4  is split into two sections, each shaft section  6  and shaft section  8  should have an associated drive mechanism  10  so that the shafts sections  6  and  8  can be rotated independently of one another. Referring to the shaft  4  below also includes the shafts  6  and  8  unless otherwise stated. 
         [0060]    A plurality of arms  12  are movably mounted to the shaft  4 . Each arm  12  has at least one wheel  14  rotatably mounted on the arm  12 . The wheel  14  is rotated by the shaft  4 , such as by a roller chain  16  or other suitable drive, such as belts or gears. The wheel  14  has at least one stamp  18 , preferably at least two stamps  18 , and most preferably at least three stamps  18  located on an outer surface of the wheel  14 . The stamps  18  can include any desired information, such as lumber grade, moisture content, heat treatment, manufacturer identification or any other information pertinent to that board. An example of a heat treatment stamp is shown in  FIG. 6 . 
         [0061]    The arms  12  are lifted up and down in relation to the conveyor  40  by a lift mechanism  20 . The lift mechanism  20  is preferably a pneumatic cylinder. Other suitable lift mechanisms include hydraulic, solenoid, or electric motor. Preferably, each arm  12  has an associated lift mechanism  20  so that they can be raised and lowed independently of one another. 
         [0062]    The printer  1  includes a wheel position device. An example of the wheel position device is an encoder  24  associated with the shaft  4  for determining the position of the stamps  18  on the wheel  24 . If there are two shafts sections  6  and  8 , each shaft should have an associated encoder  24 . The position of the wheels  14  are mechanically timed to the shaft  4 , or shaft sections  6  and  8 , so that if the position of the shaft  4  is known then the position of the stamps  18  on the wheels  14  are known. While not preferred, alternatively, encoders can be placed on each wheel  14 . While not preferred, other means in place of encoders can be utilized if desired, such as switches or photocells. 
         [0063]    The support  2  preferably also includes a support lift  30  that raises or lowers the height of the shaft  4  in relation to the conveyor  40 , which in turn raises and lowers the arms  12  and wheels  14  as a unit. Thus, the initial position of all of the wheels  14  can be set using the support lift  30 , and then the individual wheels  14  can be separately raised and lowered using the lift mechanisms  20 . An example of the support lift  30  is a pipe  32  rotatably mounted to the side supports  34 , a side arm  36  and a lock  38 . By moving the arm  36 , the pipe  32  rotates, which either lifts or lowers the arms  12  and the position of the pipe  32  can be secured using the lock  38 . Any suitable support lift  30  can be used, such as hydraulic, electric or mechanical, which is capable of lifting and lower the shaft  4  in relation to the conveyor  40 . 
         [0064]    The conveyor  40  has an associated board positioning device  52  that determines the location of a board  42  being conveyed on the conveyor  40 . The board position device  52  can be an encoder  52  that determines the shaft position and resulting lug and board position on the conveyor  40  that provides input to the controller  50  as to the location of a board  42  on the conveyor  40 . While not preferred, other means in place of encoders can be utilized if desired, such as switches or photocells. 
         [0065]    It is important that the printer  1  remains in time with the conveyor  40  and boards  42  to prevent catastrophic mislabeling. If boards are mislabeled, the entire finished lumber inventory at the mill may have to be re-graded. Since the timing between the printer  1  and the boards  42  is electronic, not mechanically via a roller chain drive as in conventional printers, the printer  1  may become out of phase with the boards  42  without the operator being aware of the mismatch, causing catastrophic results of placing incorrect stamps  18  or no stamps on the boards  42 . Thus, preferably the controller  50  includes an alert feature if the printer  1  is out of phase with the boards  42 . For example, the controller  50  can monitor the encoders  24  on shafts sections  6  and  8  and encoder  52 . The encoders  24  and  52  could be determined to be “out of phase” by a pre-set (changeable) amount either “angular” or encoder counts. At the time the stamp  18  reaches the stamping position, the location of the encoders  24  and  52  can be compared by the controller  50 . If the stamp  18  is out of phase by an amount over the allowance, the conveyor  40  can be shut off and an alarm displayed, such as “Printer out of Phase”. The operator would have to push a reset button prior to conveyor  40  being able to start up again. There would also be a small j-box or console mounted on the end frame of the printer  1  with three buttons; ADVANCE TIMING, RETARD TIMING and SET TIMING. As the printer  1  and conveyor  40  are operating, the operator could hold down either button to appropriately center the stamp  18  position on the board width being run. The controller would “remember” encoder placements for differing board widths so that when they changed over from 4, 6, 8, 10 or 12 inch widths, the printer  1  would automatically be in phase with the boards  42 . If after adjusting timing, the operator wanted the controller  50  to retain that information, he could push the SET TIMING pushbutton. 
         [0066]    Preferably, the conveyor  40  or printer  1  includes a “board present” sensor, such as a photocell, located on the conveyor beneath the grade printer so that the controller  50  can measure the width of the board  42  through encoder  52 , and know the location of the board  52  with respect to the grade printer  1 , to automatically center the grade stamp  18  on the surface of the board  42 . 
         [0067]    A controller  50  is in communication with the lift mechanisms  20 , drive mechanisms  10 , encoders  24 , and encoder  52 . Once the desired stamps are determined for the particular board  42 , the desired wheels  14  are rotated to the starting position of the desired stamps  18 . When the board  42  passes under the printer  1 , the lift mechanisms  20  drop the desired arms  12  down so that the desired wheels  14  contact the board  42  and wheels  14  rotate as the board  42  moves under the printer  1  to apply the desired stamps  18  to a width of the board  42 . When the desired stamps  18  are completely applied to the board  42 , the lift mechanisms  20  lift the arms  12  so that the wheels  14  are no longer in contact with the board  42  and undesired stamps  18  are not applied to the board  42 . Examples of suitable controllers include an Allen Bradley or other brand PLC (programmable Logic Controller). 
         [0068]    The wheels  18  should be aligned with the shaft  4  so that all similar stamps  18  are aligned in the same position. In this manner, when the wheels  14  are lowered onto the board  42 , conflicting stamp information is not applied to the board  42 . For example, for grade, all stamps  18  having the desired grade to be applied are aligned so that when the wheel  18  are lowered onto the board  42 , the same grade is stamped on the board  42  in numerous positions along the length of the board  42 . If the desired split shaft  4  configuration is utilized, shaft section  6  and shaft section  8 , one portion of the board  42  can have a first grade stamped thereon and a second portion of the board  42  can have a second grade stamped thereon. Usually, the shaft  4  is split in the center to provide two equal length shaft sections  6  and  8 . However, any length of shaft sections  6  and  8  can be used, and even more sections can be formed by further splitting the shaft  4 . Thus, the desired stamps  18  can be aligned with the first shaft section  6  and the desired stamps  18  can be aligned with the second shaft section  8  to provide a first lumber grade or other stamp on a first section of the board  42  and a second lumber grade or other stamp on a second portion of the board  42 . The wheels  14  can have different stamps. For example, a group of wheels  14  can have stamps  18  containing grades and a second group of wheels  14  can include stamps  18  having heat treatment information. If the heat treatment is to be stamped on the board  42 , the wheels  14  should be no more than two feet apart the entire length of the board  42  to comply with current rules requiring a heat treatment stamp within every two feet along the length of the board  42 .  FIG. 5  illustrates a setup in which the wheels  14  having HT stamps  18  are no more than two feet apart and stamp  18  having grades 1-3 or 4-6 are present in both sections of the shaft sections  6  and  8 . In this manner, both the desired HT and grade can be stamped on a board  42  simultaneously. 
         [0069]    The improved printer described herein as the advantage that it can be placed upstream of a trimmer  60 , and is highly flexible. Multiple different stamps  18  can be simultaneously applied in any desired location along the length of the board  42  before the board  42  is trimmed to desired lengths using the trimmer  60 . 
         [0070]    Planer mills having conveyors  40  for conveying boards  42  transversely, board positioning devices  52 , and trimmers  60  are now well known. Any desired conveyor  40 , board positioning device  52 , and trimmer  60  can be used in combination with the novel printer described herein to practice the claimed invention. 
         [0071]    While the claimed invention has been described in detail and with reference to specific embodiments thereof, it will be apparent to one of ordinary skill in the art that various changes and modifications can be made to the claimed invention without departing from the spirit and scope thereof.