Patent Publication Number: US-2005120839-A1

Title: Method of and device for trimming panels

Description:
This invention regards a method of trimming panels. More exactly, it concerns a method of processing wallboards, one side of which is provided with a pattern comprising seamlike portions along its joining edges. The invention also comprises a device for implementing the method.  
      Wallboards exist in several designs and are preferably provided with decoration suitable for the application, on one side.  
      A wallboard that has gained extensive use comprises a core panel made from waterproof plywood, with a decorating laminate glued to one side and a sealing laminate glued to the opposite side.  
      The thickness of the plywood panel is typically nine millimeters, while the thickness of the laminate is in the order of one millimeter. The side edges of the wallboard are provided with a groove, alternatively a tongue for joining together, and, as a result of their resistance to humidity and mechanical strength, the panels have been approved for use in damp rooms without requiring an additional damp course.  
      It is known to provide this type of wallboards with a ceramic tile-like pattern, where the seams of the patterns are arranged along the joining edges of the wallboards. It has been found that the joint seam between two adjacent panels is least visible if placed in a seam-like portion.  
      The width of the seam in the panel joint must be substantially uniform along the entire longitudinal extent of the seam in order to present an acceptable appearance. Due to production engineering problems related to different swelling in the various parts of the decorating laminate during production, the production of laminate panels with a relatively narrow seam along the wallboard edge has according to prior art caused great difficulties. This difference in swelling can cause the finished joint to have a variable seam width. In this connection, narrow seams mean a seam width in the order of five millimeters, such as is conventionally used in the case of wall mounted ceramic tiles.  
      When the wallboard is to be trimmed along the longitudinal edges prior to milling the tongue and groove, it is common according to prior art to move the wallboard along stationary rotating saw blades. It has been found that such a method is not sufficiently accurate for the production of wallboards where the wallboard is provided with a narrow seam decoration along its joining edges.  
      The object of the invention is to remedy the disadvantages of prior art.  
      The object is achieved in accordance with the invention, by the characteristics stated in the description below and in the following claims.  
      Due to the somewhat variable dimensions of the decorating laminate it is necessary to align each wallboard separately prior to trimming. After alignment, the wallboard is held on a stationary support, whereupon guide supported saw blades are displaced cuttingly along the edges of the stationary wallboard.  
      In a preferred embodiment the production process involves adding at least one alignment line to the decorating laminate, extending in the longitudinal direction of the wallboard, and possibly also in the transverse direction of the wallboard. The alignment line is of a design that allows it to be read by an optical reader.  
      When the wallboard has been placed on a trimming table and fixed to the trimming table, the fixing plate of the trimming table is displaced relative to the saw blades, preferably by means of servo motors, until the optical readers senses that the wallboard is in the correct position.  
      The saw blades are then displaced cuttingly along the edges of the wallboard by means of their relatively accurate guides.  
      The trimmed edges constitute an accurate reference for the subsequent processing, which includes milling the tongue and groove in the edges of the wallboard. 
    
    
      In the following, a description is given of a non-limiting example of a preferred method and embodiment illustrated in the accompanying drawings, in which:  
       FIG. 1  shows the decorating laminate side of a wallboard in the untrimmed and uncut state;  
       FIG. 2  shows the wallboard of  FIG. 1  after the trimming and cutting has taken place;  
       FIG. 3  shows a cross section of the facing edges of two wallboards, on a larger scale;  
       FIG. 4  shows the wallboard of  FIG. 3  after a tongue and groove respectively have been milled in the edges;  
       FIG. 5  shows the wallboard of  FIG. 4  after the wallboards have been joined;  
       FIG. 6  is a simplified plan view of a trimming table;  
       FIG. 7  shows the trimming table of  FIG. 6  as a wallboard enters the table;  
       FIG. 8  shows the trimming table of  FIG. 6  after the wallboard has come to an impact against a guide strip and is being aligned by means of servo motors; and  
       FIG. 9  shows the trimming table of  FIG. 6  while the wallboard is being trimmed and cut. 
    
    
      In the drawings, reference number  1  denotes a wallboard comprising a core panel  2  of waterproof plywood with a decorating laminate  4  glued to one side and a sealing laminate  6  glued to the opposite side.  
      The decorating laminate  4  of the wallboard  1  is designed in a ceramic tile pattern  8  in which the seamlike portions, hereinafter denoted seam  10 , are slightly recessed relative to the remaining of the surface.  
      The ceramic tile pattern  8  in  FIGS. 1 and 2  also comprises a border  12  that forms part of the decorating laminate  4 . The seam  10   a  which is to be located at the assembly joint between two adjacent wallboards  1  has been formed with half of its seam width on either wallboard  1 .  
      In  FIG. 1 , the wallboard  1  is shown in the untrimmed state, prior to trimming and cutting. An alignment line  14  runs parallel to the seam  10  along the middle of the wallboard  1 .  
      In order to illustrate the further processing of the wallboards  1 ,  FIG. 4  shows the wallboards after the facing edges of the wallboards  1  have been machined to give them a groove  16  and a tongue  18  respectively. In  FIG. 5 , two wallboards  1  are shown after assembly, where the seam  10   a  at the joint is formed by half a seam width from either wallboard  1 .  
      The wallboard  1  is trimmed and cut by means of a trimming table  20 . The trimming table  20  comprises an adjustment table  22  displaceably connected to the base  24  of the trimming table  20 , and which is controlled by means of two side servo motors  26  and one end servo motor  28 .  
      An end saw  30  is displaceable in the transverse direction of the trimming table  20  through use of a first guide  32 , and is arranged to be able to trim one end edge of the wallboard  1 .  
      A side saw  34  is displaceable in the longitudinal direction of the trimming table  20  by use of a second guide  36 , and is arranged to be able to trim one lateral edge on the wallboard  1 .  
      A cutting saw  38  is displaceable in the longitudinal direction of the trimming table  20  through use of a third guide (not shown), and is arranged to be able cut the wallboard  1  into two parts  1   a  and  1   b,  see  FIG. 3 .  
      A number of conveyor rollers  40  are rotatable supported in the adjustment table  22 , in the active position projecting slightly above the surface of the adjustment table  22  and the suction discs  46  through openings  42 . The conveyor rollers  40  are arranged so as to be able to transport the trimmed wallboards  1   a,    1   b  out of the trimming table  20 .  
      In the operating position, the saw blade of the cutting saw  38  projects through an elongated slot  44  in the adjustment table  22 .  
      A number of suction discs  46  are designed to keep the wallboard  1  fixed to the adjustment table  22  during the alignment and trimming of the wallboard  1 .  
      A first optical reader  48  and two other optical readers  50  connected to the base  24  are designed to read alignment lines  14 , see  FIG. 1 .  
      The optical readers  48 ,  50  control the servo motors  26 ,  28  in a manner that is known per se, by means of a control system (not shown).  
      The saws  30 ,  34  and  38  and the optical readers  48  and  50  are carefully aligned with respect to each other in order to be able to trim the wallboard  1  with the required degree of accuracy.  
      A wallboard  1  to be trimmed is moved in over the adjustment table  22  of the trimming table  20 , see  FIG. 7 , until it abuts an alignment ledge  52 , see  FIG. 8 .  
      Then the wallboard  1  is fixed to the adjustment table  22  by means of the suction discs  46 . The adjustment table  22  is displaced longitudinally and transversely by means of the end servo motor  28  and the side servo motors  26  respectively, until the optical readers  50  and  48  have located their corresponding alignment line  14  and an alignment line (not shown) added in the transverse direction of the wallboard  1 , respectively.  
      Thus the wallboard  1  is in the correct trimming position. The end saw  30  first trims one end, whereupon the side saw  34  and the cutting saw  38  carry out their respective cutting operations.  
      After the trimming has been completed, the suction discs  46  are released, whereupon the wallboards  1   a,    1   b  are moved out of the trimming table  20 .  
      The trimmed edges of the wallboards  1   a,    1   b  are located at an exact distance from the seam  10   a  and form a reference for the further processing of the wallboard  1 .