Patent Publication Number: US-2006010728-A1

Title: Means and method of securing uniform tension upon and extending the life of silkscreen

Description:
This application is a continuation-in-part of patent application Ser. No. 10/879,896, filed Jun. 29, 2004. 
    
    
     TECHNICAL FIELD  
      This invention relates to the art of silkscreen application, and in particular, a method for and apparatus enabling the extended life of a silkscreen, while allowing a more uniform tension thereon during use, resulting in a superior end product.  
     BACKGROUND OF THE INVENTION  
      Use of silkscreening to transfer colors and/or patterns to wearing apparel and other objects is well known and has been utilized for a long period of time. The art of silkscreening and the mechanisms for facilitating the silk screening have evolved and improved over the years, but the one constant is the screen itself, which also has improved, which must be fabricated of a flexible, strong, durable, fine mesh fabric, and therefore, becomes quite expensive. It has, therefore, become imperative that the amount of silkscreen material that is wasted be kept to a minimum, and further, that the screen be capable of being used many times.  
      It is with the increasing need for efficiency in mind that screens are primarily used on retensionable frames that allow multiple use of the screen and thus have become standard, but even though the frame has many improvements over the former expandable frames utilizing rectangular cross-section elements, the screen still tends to wear at the portion where the fabric is tensioned over the frame element itself.  
     SUMMARY OF THE INVENTION  
      It is with the prior art in mind that the present invention provides a means and method for securing a more uniform tension on the screen during the printing process, but also provides the opportunity of utilizing a stronger, more coarse material, where the material actually contacts the frame, increasing the life of the printing screen.  
      It is another feature of the present invention that through the utilization of an interlocking member allowing the end-to-end or side-to-side splicing of a fine mesh screen to a more economical material to allow the use of a smaller piece of the more expensive screen, and yet accomplish the desired results.  
      The utilization of a pair of opposing interlocking members which extend substantially to the outer edge of the fabric reduces the size of the pre-softening pocket and thus increases the size of the usable mesh.  
      The utilization of a smaller piece of screen material results in less material to stretch which requires less “stretch time” and therefore a quicker stabilization and earlier use.  
      Another feature of the present invention creates, through the utilization of one or more screen extensions, the ability to place greater tension upon the screen material.  
      Still another feature of the present invention is a more stable screen printing mesh.  
      Yet another feature of the present invention is the ability to utilize a greater percentage of the screen print area.  
      The use of the extension facilitates the movement of the pre-softening pocket outwardly freeing up more of the actual screen area for use enabling larger prints and facilitates the actual coating process.  
      Further, the use of the extension allows the screen to remain substantially flat during the printing process, improving the transfer while reducing the wear on both the screen and the squeegee. Empirically, the screen lasts as much as three times longer. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is a plan view of the tandem screen extender in place on a retensionable screen frame.  
       FIG. 2  is an isometric view of the interconnection between the silkscreen and the tandem extender bar and extender screen.  
       FIG. 3  is a sectional view along lines  3 - 3  of  FIG. 2 .  
       FIG. 4  is a sectional view showing the inventive extender as used on one form of the tensionable frame.  
       FIG. 5  is a sectional view showing the extender bar and extender tandem as shown on a second form of retensionable roller frame.  
       FIG. 6  is a plan view utilizing the tandem system in conjunction with a second extender.  
       FIG. 7  is graphical comparison of the amount of screen which is usable utilizing the two systems of securement.  
       FIG. 8  is a graphical representation of the amount of pressure necessary utilizing the securement system of the prior art.  
       FIGS. 9 and 9 A depict a planar and an elevational view of the invention suspension system.  
       FIGS. 10 and 10 A compare the portion of readily usable space of the screen utilizing the prior art and inventive suspension systems. 
    
    
     BEST MODE FOR CARRYING OUT THE INVENTION  
      As seen in  FIG. 1 , a rectangular silk screen panel  2  is secured to interconnecting or splicing members  4  along the majority of each of its edges, and the interconnecting splicing or tandem members  4  is likewise connected to extender mesh strips  6 , which are then, as explained hereinafter, each attached to one of the linear elements  8  of the retensionable frame. Each of the side elements  8  are interconnected by a rigid corner member  10 , and as known in the prior art, a tensioning element, judiciously applied to the side members  8 , allows the appropriate tension to be placed upon silkscreen member  2 .  
      Reference is now had to  FIG. 2 , wherein it can be seen that the screen mesh  2  is secured to the tandem unit  4  by being secured by a spline element  12 , which as explained hereinafter, is locked into the tandem unit  4 . The extender mesh  6  likewise is secured to a spline member  14  and again, as explained hereinafter, is locked into member  4 . The exterior or opposite edge of extender unit  6  is likewise secured to a spline  16 , which is subsequently secured to the retensionable frame member.  
      Reference is now had to  FIG. 3 , wherein it can be seen that the tandem unit  4  is a wide block-shaped W in cross-section with vertical exterior legs  18  and  20  and a modified T-shaped interior leg  22 , such that the fabric  2  is wrapped around spline member  12 , which is then captured in a protective locking element  24 , including a second protruding lip  26 , which is snapped beneath the protrusion of T-shaped center leg  22 . Likewise the extender mesh  6  is wrapped around spline member  14 , which is then snapped into the opposite side of tandem  4  and locked in place beneath the opposite lip of the T-shaped center leg  22 .  
      As stated hereinabove,  FIGS. 4 and 5  depict two distinct retensionable frame members; the one shown in  FIG. 4  includes tubular sides which are kept from bowing by rigid supports  30  which lie inside the roller tension element  32  to which the extender  6  is secured. Extender  6  is attached to the spline member  34 , which is very similar to spline member  14 , described hereinabove.  FIG. 5  depicts a similar attachment to a retensionable frame, wherein the roller  36  does not have a support member, but the screen may be cut to accommodate any bowing.  
      Reference is now had to  FIG. 6  which is similar to  FIG. 1  and identical numbers will identify identical elements. It is to be noted, however, that in this particular depiction, extender member  6  is actually secured to a second spline  16  to secure the structure to another tandem element, allowing a daisy chain extender  38  which is then secured to the frame element  8 . This particular configuration allows increased tension upon large screens by allowing the tension to be originally applied through extender member  6  and then removing extender  38  once a predetermined extended size is reached and securing spline  16  directly to the roller  8  and applying further tension. It is to be understood that in certain circumstances more than one extender could be used depending upon the relative size of the screen and frame. Further, when greater tension is required a series of extenders may be used, sequentially removing them as the screen expands (the screens do not quickly return to size) until the desired tension is reached. It is the overall goal that the actual silkscreen never contacts the frame.  
      The graphical representation of  FIG. 7  depicts a frame  40  having a first extender  42  and the screen  44 . The line A depicts the perimeter P′P′ of the useful area of the screen  44  when fastened to the frame  40  in the manner known in the prior art, whereas the line B and perimeter P′P′ illustrates a much greater area when using the extender or trampoline suspension  42 .  
       FIG. 8  illustrates the methodology of generating the curve(s) of  FIG. 7  in that the amount of pressure required to achieve an acceptable screen print at the squeegee is measured, and the rapid increase required as the frame is approached is reflected in the curve A.  
       FIGS. 9 and 9 A depict the inventive concept of having a separate frame  43  and an extended mesh  42  intermediate the exterior frame  40  and the screen mesh  44  to stabilize the screen mesh  44  and render a much greater portion usable for quality screening.  
       FIGS. 10 and 10 A graphically display the functional differences when the intermediate frame  43  extending web  42  are used.  
      In addition to the advantages mentioned hereinabove, it is to be noted that the pre-softening of the corner can actually occur in the screen  2  itself or can in fact be accomplished by having splines  4  be shorter than the relative side of the fabric  2 , allowing the pre-softening to occur in the extender mesh  6 .  
      Further, the tandem stretching bar prevents overtensioning or breaking the silk screen fabric by physically intervening or interrupting the process when it contacts the stretching frame.  
      The membrane and screen printing frame connector bar can be preshaped with presoftened corner bands and deflection compensation to accept non-tailored screen printing mesh.  
      Thus, as can be seen, the present invention gives the silkscreen handler a method and apparatus for greatly reducing the amount of fabric used, stabilizing the fabric during use and further extends the life of the fabric.