Patent Publication Number: US-10315361-B2

Title: Method of forming raceway knockout

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 13/837,981, filed Mar. 15, 2013, which claims priority to U.S. Provisional Patent Application No. 61/707,375, filed Sep. 28, 2012. The entire contents of both applications are incorporated by reference herein. 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention relates to raceway knockouts, such as disclosed in U.S. Pat. No. 5,195,287. A conventional office panel or raceway supports electrical and telecommunications wire or conduit. The raceway includes optional blank or knockout portions to permit a user to access the wires. In general, the knockout is formed by removing the blank from the raceway, creating an opening. The knockout is then inserted into the opening and re-attached to the raceway. Although various methods are known for re-attaching the knockout, these methods suffer from two main flaws. First, the knockout is too readily removable from the raceway such that the knockout can be separated from the raceway unintentionally. Second, the knockout or an attaching element stands proud of the raceway, so that the knockout and the raceway do not form a seam that is flush with the raceway. 
     SUMMARY OF THE INVENTION 
     In one embodiment, the invention provides a method for forming a knockout on a raceway. The method includes removing a knockout from the raceway to form an opening, positioning the knockout within the opening, and thereafter attaching the knockout to the raceway by welding the knockout and the raceway together. 
     In another embodiment, the invention provides a method for joining a first plastic workpiece and second plastic workpiece. The method includes positioning an edge of the first workpiece adjacent an edge of the second workpiece so that the edges engage one another in a facing relationship; positioning a welding horn adjacent the first workpiece and the second workpiece, a welding surface of the welding horn being in contact with both the first workpiece and the second workpiece; and welding the edges of the first and second workpieces together by an ultrasonic welding process. 
     In yet another embodiment, the invention provides a welding horn for welding plastic material along a weld seam. The welding horn includes a welding surface adapted to weld the plastic material and a plurality of energy directors. The plurality of energy directors are positioned on the welding surface and each energy director includes a truncated pyramid having a recessed peak. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a raceway and a knockout removed from the raceway. 
         FIG. 2  is a perspective view of the raceway of  FIG. 1  with the knockout inserted in an opening of the raceway. 
         FIG. 3  is a perspective view of a welding horn. 
         FIG. 4  is an enlarged perspective view of the welding horn of  FIG. 3 . 
         FIG. 5  is a perspective view of the welding horn of  FIG. 3  applied to the raceway of  FIG. 2 . 
         FIG. 6  is a cross-section view of the welding horn during a welding process. 
         FIG. 7  is an enlarged portion of  FIG. 5 . 
         FIG. 8  is a perspective view of one side of the raceway of  FIG. 2  with the knockout re-attached. 
         FIG. 9  is a perspective view of the other side of the raceway of  FIG. 2  with the knockout re-attached. 
         FIG. 10  is a plan view of a welding horn according to another embodiment. 
         FIG. 11  is a plan view of one side of the raceway of  FIG. 2  with the knockout re-attached by the welding horn of  FIG. 10 . 
     
    
    
     Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. 
     DETAILED DESCRIPTION 
       FIG. 1  shows a first workpiece, such as a panel or raceway  10 , and a second workpiece, such as a blank or knockout  20 , that is formed by punching or removing a portion of the raceway  10  and thereby forming a slot or opening  30  on the raceway  10 . In one embodiment, the raceway  10  and knockout  20  are made from a plastic or polymeric material and the knockout  20  is removed from the raceway  10  by a punching process. In the illustrated embodiment, the knockout  20  has a generally rectangular shape with rounded corners. In addition, the opening  30  is completely enclosed by the raceway  10 . In other embodiments, the knockout  20  may have a different shape, or the opening  30  may be formed along an edge of the raceway  10 . 
     As shown in  FIG. 2 , after the knockout  20  has been removed from the raceway  10 , the knockout  20  is re-positioned within the opening  30 . In one embodiment, the knockout  20  is held in place by friction between the edges of the knockout  20  and the edges of the raceway  10 . The knockout  20  is aligned with the raceway  10  so that each edge of the knockout  20  is directly adjacent and abuts an edge of the raceway  10 , thereby forming a seam  40  between the raceway  10  and the knockout  20 . That is, the edges of the knockout  20  are positioned to engage the edges of the raceway  10  around the opening  30  in a facing relationship so that there is no overlap between the knockout  20  and the raceway  10 . Stated another way, the knockout  20  is coterminous with the opening  30 . In one embodiment, the knockout  20  is removed from and re-inserted into the raceway  10  by a double-punch apparatus that punches the knockout  20  out of the raceway  10  in a first motion and moves the knockout  20  back into the opening  30  in the second motion. In some embodiments, the knockout  20  and the raceway  10  are positioned in a side-by-side relationship such that at least one edge of the knockout  20  and one edge of the raceway  10  are directly adjacent and abut one another. 
       FIG. 3  shows a sonotrode or welding horn  50  for welding the knockout  20  to the raceway  10  by an ultrasonic welding process. The horn  50  includes a welding surface  60 . The welding surface has a profile or shape that corresponds to the shape of the seam  40 . In the illustrated embodiment, the horn  50  includes a non-welding surface positioned adjacent the welding surface  60 . The welding surface  60  has a rectangular shape and at least partially encloses the non-welding surface  70 . In other embodiments, the welding surface  60  and/or the non-welding surface  70  can have a different shape configured to apply an acoustic vibration along the interface between the raceway  10  and the knockout  20 . 
     As shown in  FIG. 4 , the welding surface  60  includes multiple energy directors  80  for forming welds along the seam  40 . Each energy director  80  is formed as a truncated pyramid  90  having a recessed peak  100 . In the illustrated embodiment, the recessed peak  100  is formed as a dimple having a generally hemispherical shape. In the illustrated embodiment, the energy directors  80  are arranged in multiple rows extending along the welding surface  60 . The energy directors  80  generally form a grid pattern along the welding surface  60 . In other embodiments, the energy directors  80  are arranged in order to reduce the possibility that large portions of the seam  40  are aligned with valleys or spaces between the energy directors  80 , which would prevent consistent welding along the seam  40  and result in large gaps between welds. For instance, in some embodiments, the rows of energy directors  80  may be staggered relative to one another so that adjacent energy directors  80  are offset. In other embodiments, the energy directors  80  are arranged such that the maximum distance between energy directors  80  that form welds on the seam  40  (and therefore the maximum distance between adjacent welds along the seam  40 ) is less than a predetermined length. 
     As shown in  FIG. 5 , the raceway  10  and the re-inserted knockout  20  are positioned between the horn  50  and an anvil  110 . The welding surface  60  is generally aligned with the seam  40  and positioned to contact both the raceway  10  and the knockout  20 . As shown in  FIGS. 6 and 7 , at least some of the energy directors  80  straddle or span across the seam  40  and contact both workpieces, creating several discrete welds along the seam  40  between the raceway  10  and the knockout  20 . The welding horn  50  transmits an acoustic vibration to the raceway  10  and the knockout  20  to melt each workpiece along the seam  40 . The energy directors  80  concentrate the acoustic vibration laterally to melt the adjacent edges of the raceway  10  and knockout  20 . As the melted edges are solidified, the raceway  10  and the knockout  20  are bonded so that the knockout  20  may be removed by a user without the need for tools and without deforming the raceway  10 . In one embodiment, the welding surface  60  is applied to the seam  40  for between approximately one and three seconds, and applies a vibration at a frequency of approximately 20,000 cycles per second (20 kHz) and an amplitude of approximately 1.5 thousandths of an inch. These parameters can be altered to adjust the strength of the weld with a high degree of accuracy. 
     As shown in  FIG. 8 , the horn  50  forms multiple impressions  120  on the side of the raceway  10  to which the horn  50  is applied. The impressions  120  correspond to the shape of the energy directors  80 . By comparison,  FIG. 9  shows that the reverse side of the raceway  10  does not include any impressions. To remove the knockout  20 , a user applies pressure to the knockout  20  to cause the knockout  20  to break away from the raceway  10  along the seam  40 . The user may then pass conduit, such as electric wiring, through the resulting opening  30 . The welding process provides a method for re-attaching the knockout  20  to the raceway  10  such that the knockout  20  is flush with and uniform with the raceway  10 , and so that the knockout  20  will not fall out of the opening  30  until the user wishes to remove the knockout  20 . In addition, the welding horn  50  permits two adjacent workpieces to be joined along an edge rather than requiring that the workpieces overlap. 
     In the illustrated embodiment, the raceway  10  and knockout  20  have the same thickness, and the surfaces of the raceway  10  and the knockout  20  to which a welding horn  50  is applied are coplanar. 
       FIG. 10  illustrates another embodiment of the welding horn  250 . In this embodiment, the energy directors  280  are arranged in multiple rows extending the length of the welding surface  260  and generally form a grid pattern along the welding surface  260 . However, each energy director  280  is rotated about an axis extending perpendicularly from the welding surface  260 . As a result, the grid pattern includes rows of energy directors  280  that extend in a direction that forms an acute angle with respect to an edge of the welding surface  260 , rather than being parallel or perpendicular to the edge. In the illustrated embodiment, the angle is approximately 45 degrees relative to an edge of the welding surface  260 . In other embodiments, the angle may be changed to increase the contact between both workpieces and an energy director, or to accommodate the geometry of the seam. The angled orientation reduces the possibility that a seam between two workpieces (e.g., seam  40 ) will be aligned along a space between the energy directors  280 , which would prevent the energy director  280  from contacting both workpieces across the seam and inhibit welding. The angled orientation of the energy directors  280  therefore improves the quality of the weld.  FIG. 11  illustrates a pattern of impressions  320  formed on the side of the raceway  10  to which the horn  250  is applied. 
     In other applications, the first workpiece and the second workpiece have different thicknesses so that the surfaces to which the welding horn  50  is applied are coplanar but the reverse surfaces are not coplanar. Also, in other embodiments the surfaces of the first workpiece and the second workpiece to which the welding horn  50  is applied are substantially coplanar but are offset by a small distance. 
     Various features of the invention are set forth in the following claims.