Abstract:
A laminating press comprises a plurality of press units adapted to individually receive respective stacks of individual laminae and press the laminae together face to face so as to independently form in parallel a corresponding number of laminated products. The press units are mounted along a conveyor and displaced thereby between a loading position and a discharged position while individually holding their respective stacks of laminae in compression.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates generally to lamination processes and apparatuses and, more particularly, to a laminating press suited for making laminated beams.  
         [0003]     2. Description of the Prior Art  
         [0004]     A variety of laminated wood beams are used in construction work today as joists, girders, posts, columns or other structural pieces. Laminated wood beams are known to be stronger, more resistant and more dimensionally stable than continuous wood beams.  
         [0005]     The laminated beams are made from stack of individual laminae coated with an adhesive and then maintained face to face in compression while the adhesive is allowed to set.  
         [0006]     The prior art laminating presses used to maintain the stacks of laminae in compression are relatively complex, cumbersome and generally very costly to purchase.  
       SUMMARY OF THE INVENTION  
       [0007]     It is therefore an aim of the present invention to provide a new laminating press which is relatively simple and economical.  
         [0008]     It is also an aim of the present invention to provide a laminating press which is of compact construction.  
         [0009]     Therefore, in accordance with an aspect of the present invention, there is provided a laminating press comprising a frame, a conveyor mounted to said frame, and a plurality of press units adapted to individually receive respective stacks of individual laminae and press the laminae together face to face so as to independently form in parallel a corresponding number of laminated products, the press units being mounted along the conveyor and displaceable thereby between a loading position and a discharged position while individually holding their respective stacks of laminae in compression. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]     Having thus generally described the nature of the invention, reference will now be made to the accompanying drawings, showing by way of illustration a preferred embodiment thereof, and in which:  
         [0011]      FIG. 1  is a perspective view of a beam-laminating press in accordance with an embodiment of the present invention;  
         [0012]      FIG. 2  is a side elevation view of the beam-laminating press shown in  FIG. 1 ;  
         [0013]      FIG. 3  is an enlarged side view of an edge aligning system forming part of the beam-laminating press shown in  FIG. 1 ;  
         [0014]      FIG. 4  is a side view of a backstop mechanism forming part of the beam-laminating press shown in  FIG. 1 ; and  
         [0015]      FIGS. 5   a  and  5   b  are schematic side views of an automatic release system forming part of the beam-laminating press shown in  FIG. 1 . 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0016]      FIG. 1  illustrates an embodiment of a laminating press  10  suited for making laminated cross lumber beams or timbers B composed of a plurality of elongated wood pieces bonded together face to face.  
         [0017]     The laminating press  10  generally comprises an infeed conveyor  11  for feeding the press  10  with individual laminae, for instance elongated wood planks, a frame  12  defining an inclined plane on which is mounted a hydraulic conveyor  14 , a plurality of individual press units  16  ( 13  in the illustrated example) fixedly mounted at regular intervals along the conveyor  14  and driven thereby, an edge aligning system  18  mounted on a side of the infeed conveyor  11  opposite the frame  12 , and a discharge conveyor  20  extending parallel to the infeed conveyor  11  underneath the lower end of the frame  12  for successively receiving laminated beams B from the individual press units  16 . The inlet and discharge conveyors  11  and  20  are preferably provided in the form of endless belt conveyors and are of conventional construction.  
         [0018]     The frame  12  is made from heavy sturdy steel tubes assembled to each other such as by welding. The frame  12  is configured to support the hydraulic conveyor  14  carrying the press units  16  at an angle of about preferably 45 degrees while providing the required clearance for the passage of the press units  16  on the return run or bottom run of the conveyor  14  as shown in  FIGS. 1 and 2 . Mounting the conveyor  14  at an angle is advantageous in that it provides for significant space saving and, thus, important operating cost reductions  
         [0019]     The hydraulic conveyor  14  comprises a plurality (five in the illustrated embodiments) of laterally spaced-apart endless chains  22  trained about pairs of longitudinally spaced-apart sprockets  24   a  and  24   b . The top and bottom sprockets  24   a  and  24   b  are mounted to respective axles extending transversally at the top and bottom ends of the frame  12 , respectively. At least one of the axles, preferably the one at the top end of the frame  12 , is driven by a hydraulic motor  26  ( FIG. 2 ) through a chain transmission  28  to drive the laterally spaced-apart endless chains  22  in unison in either one of a forward direction and a backward direction. As shown in  FIG. 4 , the chain transmission includes a sprocket wheel  38 . A backstop mechanism  40  is selectively engageable with the sprocket wheel  38  to substantially eliminate the back loads on the hydraulic motor  26 , thereby allowing using a smaller and less expensive motorization to drive the chains  22  and, thus, the press units  16 . It also advantageously provides for the use of a bi-directional motor.  
         [0020]     The backstop mechanism  40  includes a pawl  42  in the form of a small pivoted latch selectively engageable with the teeth of the sprocket wheel  38  to lock the same against clockwise rotation. As shown in  FIG. 4 , the pawl  42  is pivoted between an idle position and a locking position (shown in broken lines) by a small pneumatic or hydraulic cylinder  44 . The pawl  42  is normally maintained in its idle position by cylinder  44 .  
         [0021]     As shown in  FIGS. 1 and 2 , each press section  16  includes a stationary jaw or platen  52 , for instance in the form of an elongated rectangular tube member fixedly secured to the endless chains  22  of the conveyor  14  and extending transversally with respect thereto, a stack support preferably provided in the form of a number of upstanding backing members  54  extending at right angles from the stationary jaw  52  at regular intervals therealong to form a side arresting surface for the stack of laminae to be pressed bonded together, an elongated plate  56  extending parallel to the stationary jaw  52  to unitize the backing members  54  at the end thereof opposite to the stationary jaw  52 , a movable jaw or platen comprising a number of movable jaw segments  58  operated by pairs of pneumatic actuators  60  mounted to the elongated plate  56 . The pneumatic actuators  60  are preferably provided in the form of pneumatic dampers or chock absorbers of the type used in truck and tractor suspensions. The use of that type of fluid driven actuator is advantageous in that it provides for the application of a uniform pressure all along the length of the stack of laminae and prevents the wood from being damaged. The use of pneumatic actuators instead of hydraulic cylinders is also advantageous in that it permits to reduce the size of each press units, which results in savings in operating and maintenance costs. Each movable jaw segment  58  is displaceable toward and away from the stationary jaw  52  to press and release the stack of elongated laminae loaded in the press units  16 . The movable jaw segments  58  permit to apply individual pressing load along the stack of elongated laminae, thereby allowing accommodating variations in the height of the stack along the length thereof. The application of punctual pressing loads provides added flexibility. The above-described press unit  16  is advantageous in that it provides for the lamination of beams of various thickness, width, length and type of wood without variations in the quality of the final product. However, it is understood the movable jaw segments  58  could be replaced by a continuous elongated jaw or platen. Also, the elongated plate  56  could be replaced by a number of plate segments pairing the baking members  54  and supporting a pair of pneumatic actuators  60 .  
         [0022]     As shown in  FIGS. 5   a  and  5   b , each press unit  16  is further provided with an automatic pressure release system  61  to automatically release a stack of bonded laminae directly onto the discharge conveyor  20  each time a press unit  16  engages a triggering arm  63  fixed on one side of the lower end of the frame  12 . More particularly, the system  61  comprises a valve  65  displaceable from a closed position ( FIG. 5   a ) for maintaining the pressure within the pneumatic actuators  60  to an open position ( FIG. 5   b ) for purging the fluid pressure from the actuators  60 , thereby allowing the bonded laminae to drop by gravity onto the discharge conveyor  20 . The valve  65  is displaced between the open and closed positions thereof by an actuating lever  67 . As shown in  FIGS. 5   a  and  5   b , while the press unit  16  is driven forward by the conveyor  14 , the lever  67  contacts the triggering arm  63  which causes the lever  67  to pivot in the direction indicated by arrow  69  to the position shown in  FIG. 5   b , thereby causing the pressure in the pneumatic actuators  60  to be released.  
         [0023]     As best shown in  FIGS. 2 and 3 , the edge aligning system  18  comprises a frame  62 , a number of laterally spaced-apart pivot arms  64  pivotally mounted to the frame  62  and operated by respective hydraulic cylinders  66  (four in the illustrated example) which are, in turn, pivotally mounted between the frame  62  and the pivot arms  64 . The arms  64  are rigidly link together at their upper ends by a cross tubular member  68 . A number of spring-loaded pressing members  70  are pivotally mounted at regular intervals along the cross tubular member  68 . As shown in  FIG. 3 , each spring-loaded pressing member  70  comprises a pusher  72  mounted for sliding movement on a series of pins  74  extending at right angles from a base member  76 . Springs  80  are mounted about the pins  74  between the base member  76  and the pusher  72 . As shown in  FIG. 2 , the cylinders  66  are retracted to cause the pivot arms  64  to pivot from an idle position (shown in broken lines) to an operational position in which the pusher  72  are pressed against the side edges of the stack of laminae that has just been loaded in one of the press units  16 . By so conjointly applying the pushers  72  against the side edges of the stack of laminae, the offsets between each of the laminae can be reduced before the laminae be pressed bonded together face to face by the pressing unit  16  in which the stack has been loaded. This system contributes to reduce wood fibre waste.  
         [0024]     In operation, individual elongated laminae, such as elongated wood members, are fed lengthwise to the press  10  via the infeed conveyor  11 . The hydraulic conveyor  14  is operated to position one of the press units  16  at a loading position at the bottom of the frame  12 , as shown in  FIGS. 1 and 2 . Then, the conveyor  14  is stopped and pawl  42  is engaged with sprocket wheel  38  to prevent the transmission of backlash forces to the motor  26 .  
         [0025]     The press unit  16  to be loaded with a stack of laminae is preferably stopped at an angle to the infeed conveyor  11 , as shown in  FIG. 2 . The individual laminae are then manually stacked into the press unit  16 . It is understood that the opposed faces of the laminae are covered with an adhesive. It is also understood that depending on the length of the laminae, more than one stack could be placed end-to-end into a same press unit  16  in order to simultaneously form a corresponding number of laminated beams.  
         [0026]     Once the individual laminae have been properly stacked into the press unit  16 , the cylinders  66  of the edge-aligning system  18  are retracted to cause the pushers  72  to press the stack of laminae against the backing members  54  of the press unit  16  in order to appropriately align the laminae with respect to each other. While the stack of laminae is held at the sides thereof between the pushers  72  and the backing members  54 , the pneumatic actuators  60  of the press unit  16  are connected by the operator to a source of pneumatic pressure to cause the mobile jaw segments  58  to move towards the fixed jaw  52 , thereby pressing the laminae face to face. The pneumatic actuators  60  are pressurized to the desired pressure and then disconnected from the pneumatic source. Thereafter, the hydraulic cylinders  66  are expanded to cause the arms  64  to pivot back to their idle position (shown in broken lines in  FIG. 2 ), thereby moving the pushers  72  away from the compressed stack of laminae held between the mobile jaw  58  and the fixed jaw  52  of the press unit  16 .  
         [0027]     The hydraulic conveyor  14  is then powered back to bring the next press unit  16  in position for receiving and compressing another stack of laminae as per the procedure described hereinabove. The press units  16  are, thus, sequentially loaded. While the press units  16  are carried about the loop defined by the conveyor  14 , the mobile jaw segments  58  are maintained press against the stacks of laminae to cure the beams. During the setting period, the press units  16  are sequentially brought to an unloading position at the lower end of the return line of the conveyor  14  above the discharge conveyor  20 . The press units  16  are sequentially unloaded each time a press unit  16  completes its run about the conveyor  14  and passes by the triggering arm  65 . Once the actuating lever  67  of the valve  65  of the pneumatic actuators  60  of the press unit  16  passing by the triggering arm  63  has been rotated to its open position, as shown in  FIG. 5   b , the pressure exerted by the mobile jaw segments  58  on the laminated beam is released and the beam falls down by gravity onto the discharge conveyor  20 . Guards  82  are preferably fixedly mounted on the endless chains  22  between each press unit  16  to ensure that the laminated beams fall onto the discharge conveyor  20  and not on a side thereof. The guards  82  are preferably provided in the form of upstanding tubular members slightly inclined to the vertical in a direction away from the press units  16  located immediately downstream thereof with respect to the direction of travel of the press units  16  (i.e. the counter clockwise direction in the embodiment illustrated in  FIG. 1 ).  
         [0028]     The above described press  10  is cheaper and simpler than conventional laminating press of equivalent capacity. Furthermore, it is of compact construction which results in important cost savings.  
         [0029]     While a detailed description of an embodiment of the present invention has been given, it is understood that many changes and modifications may be made without departing from the spirit of the invention. All such modifications are intended to be included within the scope of the appended claims.