Patent Publication Number: US-8112848-B2

Title: Slider for a fluid tight slide fastener

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The entire disclosure of British patent application No. GB0618329.7 filed on Sep. 18, 2006 is incorporated herein by reference in its entirety. 
     BACKGROUND 
     1. Field of the Invention 
     This invention relates to a slider for a fluid tight fastener. 
     2. Description of the Related Art 
     Examples of such a fluid tight fastener are described in EP-A-1057423 and EP-A-1175842. In such a fluid tight fastener, a coil like continuous coupling member is sewn onto a tape surface near an edge of the tape. The other surface of the tape is coated with a fluid proof layer which extends beyond the edge of the tape to form a sealing lip. When the coupling members of adjacent tapes are engaged, the sealing lips of the fluid proof layers abut to form a seal. Such fasteners can provide a reasonably good seal against liquids or gasses, depending on various factors such as the design of the sealing lips of the fluid proof layers, the extent to which they are urged together by the coupled elements and the extent of flexing of the fastener in use. 
     The slider shown in EP-A-1057423 and EP-A-1175842 incorporates a guide plate or “guide flange” in the form of a thin blade which projects from the wedge which joins the upper and lower plates of the slider. This guide plate extends between the outer ends of the coupling elements and the sealing lips. Thus the guide plate creates upper and lower paths within the slider and serves to ensure more accurate alignment of the coupling elements as they are brought together and enables greater pressure to be exerted on the sealing lips whilst keeping them aligned. 
     In practice, the slider shown in EP-A-1057423 and EP-A-1175842 has been made of three parts, with the guide plate being formed separately and sandwiched between the upper and lower plates and guide posts. This adds significantly to the cost of the production process. 
     SUMMARY 
     Thus a first aspect of the present invention provides a slider for a fluid tight slide fastener, the slider having upper and lower plates joined together by a guide post and a guide plate formed on the guide post to cooperate with the upper and lower plates to guide the coupling elements and sealing lips of the slide fastener, wherein the slider is integrally formed. In particular the slider may be die cast or moulded as a single, integral member of metal or plastics material. By integrally forming the slider we are able to strengthen the slider, and in particular in the region between the upper plate and the guide plate where the slider parts are subject to greater separation forces as the slider is pulled along the fastener to urge the sealing lips together. This substantially reduces the cost of the production process and also leads to an improvement in product quality because of the avoidance of any misalignment or other errors which may arise in an assembly process. 
     A difficulty with the prior art slider design was the use of a relatively thin guide plate which extended a relatively long distance from the guide post and so was unsupported. This could not be reliably moulded as an integral part of the slider. 
     In another feature of the invention, the trailing portion of the guide plate is joined to the upper plate by a web which extends from the guide post. The web may extend to the trailing edge of the guide plate. 
     In another feature of the invention, the forward part of the guide plate is thickened relative to the trailing end. The outer edge of the thickened part may be chamfered. 
     The underside of the guide plate may be substantially flat, forming with the lower plate a guide channel for the coupling elements. The underside of the trailing end may be thickened where it joins the guide post. 
     In one embodiment, the trailing end of the upper plate has downwardly projecting guide flanges extending perpendicularly from the edge of the upper plate. In another embodiment, the guide flanges may be wedge shaped in cross section, to form a guide channel which is narrowed at its upper region, near the upper plate. 
     Other aspects and preferred features of the invention will be apparent from the following description and the accompanying claims. 
     The invention will be further described by way of example with reference to the accompanying drawings in which: 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a side view of a prior art slider. 
         FIG. 2  is a plan view of the slider of  FIG. 1 . 
         FIG. 3  is an end view of the slider of  FIGS. 1 and 2 , on a slider fastener. 
         FIG. 4  is a side view of a slider forming a first embodiment of the invention. 
         FIG. 5  is a trailing end view of the slider of  FIG. 4 . 
         FIG. 6  is a longitudinal cross-section of the slider of  FIG. 4 . 
         FIG. 7  is a plan view of the slider of  FIG. 4 . 
         FIG. 8  is a trailing end view of a second embodiment of the invention. 
         FIG. 9  is a longitudinal cross-section view through the embodiment of  FIG. 8 . 
         FIG. 10  is a perspective view of the embodiment of  FIG. 8  with an upper plate cut away. 
         FIG. 11  is a longitudinal cross-sectional view of a slider according to a third embodiment of the present invention. 
         FIG. 12  is a cross-sectional view taken on line A-A of  FIG. 11 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to  FIGS. 1 and 2 , these show a side view and plan view of a prior art slider  1 . Slider  1  has upper and lower plates  2 ,  3  with a bridge  4  formed on the upper plate  2  for receiving a slider puller (not shown). Upper and lower guide post halves  5 ,  6  depend from the upper and lower plates and sandwich a guide plate  7  between them. As seen in  FIG. 3 , side flanges  8 ,  9  depend from the left and right side edges of the upper and lower plates  2 ,  3  at the trailing ends of the plates so as to extend longitudinally of the slider  1 . When the slider  1  moves forward, the side flanges  8 ,  9  serve to couple the coupling elements  10  and urge sealing lips  11  of the fastener into abutting engagement with each other. As also illustrated in  FIG. 3 , the fluid tight slide fastener comprises tapes  12  with coil like coupling elements  10  mounted on one surface  13  near the outer edge  14  of the respective tapes. A fluid proof coating  15 , such as a rubber, elastomer or thermoplastics material, is provided on the other, upper surface  16 . The coating  15  has sealing lips  11  formed integrally therewith, which sealing lips  11  are guided by the guide plate  7  and upper plate  2  into an abutting, sealing position as the fastener elements  10  are coupled together. A reinforcing tape  17  is provided on the underneath surface of the tapes  12 . 
     Referring to  FIGS. 4 and 5 , these drawings show a slider  20  in accordance with the invention for a fluid tight slide fastener of the type described above. The slider has parallel upper and lower guide plates  21 ,  22 , and a guide post  23  joining both the guide plates  21 ,  22 . In addition, a guide plate  24  is disposed between the upper plate  21  and the lower plate  22  and spaced from the upper and lower plates  21 ,  22 , respectively. The guide plate  24  is joined with the guide post  23 . As shown in  FIG. 4 , the guide plate  24  extends out from the guide post  23  towards the forward and trailing ends  25 ,  26  of the slider  20 . As shown in  FIG. 5 , the guide plate  24  also extends toward opposed left and right sides of the guide post  23 . The upper and lower guide plates  21 ,  22 , guide post  23  and guide plate  24  are integrally formed, that is formed of a single unitary piece. They may be formed of metal by die-casting or of plastics by moulding, for example. 
     A bridge  37  for attaching a puller (not shown) is also integrally formed on the upper surface  38  of the upper plate  21 . The bridge  37  includes a front leg  37   a  mounted on the front end  25  of the slider  1 , a rear leg  37   b  mounted on the rear end  26  of the slider  1  and a bridge proper  37   c  connecting the front and rear legs  37   a ,  37   b  at their respective upper ends. Other structures for attaching a puller may be used, as known in the art. 
     The upper and lower plates  21 ,  22  are of generally the same outline or shape, as viewed in a plan. As seen in  FIG. 7 , both the plates  21 ,  22  taper towards the trailing end  26 . Upper and lower side flanges  27 ,  28  depend from the left and right opposed sides of the respective upper and lower plates  21 ,  22  over the tapering portion of the plates  21 ,  22 . The upper flange  27  is formed so as to project from the upper plate  21  toward the lower plate  22  and to stand at a right angle relative to the upper plate  21 , while the lower flange  28  is formed so as to project from the lower plate  22  toward the upper plate  21  and to stand at a right angle relative to the lower plate  22 . As known in the art, the lower flange  28  serves to urge the coupling elements  10  of the opposed tapes  12  toward each other and into engagement when the slider  20  moves forward. On the other hand, the upper flanges  27  serve to urge the sealing lips  11  toward each other and into abutting engagement with each other, when the slider  20  moves forward. Although the lips  11  would be pulled together as the coupling elements  10  are engaged, the side flanges  27  will reduce the strain on the coupling elements  10  and their connection to the tapes  12 , and also serve to ensure consistent orientation of the sealing lips  11 . 
     The guide plate  24  is a particular feature of this invention. Forming the upper and lower plates  21 ,  22  guide post  23  and guide plate  24  as an integral unit serves to strengthen the slider  20 . We also enhance the strength by increasing the thickness of the guide plate  24  and providing a greater mating area with the upper plate  21 . 
     As better seen in  FIG. 10 , the guide post  23  has a generally rectangular cross-section with a tapered end  23   a , ending in a trailing edge  39  of the guide post  23 . 
     Referring particularly to  FIGS. 5 and 6 , a web  29  joins the trailing portion  30  of the guide plate  24  to the upper plate  21 . Web  29  tapers in thickness from the guide post  23  to the trailing edge  31  of the guide plate  24 , to provide a smooth transition path for the sealing lips as they are urged together. 
     In the embodiment shown, the web  29  extends from the guide post  23  to the trailing edge  31  of the guide plate  24 . However, the web  29  may stop short of the trailing edge  31 . 
     The guide plate  24  includes a forward portion  32  extending from the guide post  23  toward the forward end  25  of the slider  20 , a tailing portion  30  extending from the guide post  23  toward the tailing end  26  of the slider  20  and a side portion  33  extending from the guide post  23  sideways or laterally of the slider  20   
     The forward portion  32  and the side portion  33  of the guide plate  24  are thickened, being thicker than the trailing portion  30  over a region extending approximately from the trailing edge  39  of the guide post  23  toward the forward end  25  of the slider  20 . The outer edge of the forward portion  32  and the side portion  33  is tapered in thickness, and has a chamfer  34 . The chamfer  34  is formed on the upper surface of the guide plate  24  and is disposed so as to face the upper plate  21 . A fillet  35  is provided on the under side of the trailing portion  30  of the guide plate  24  at the junction with the trailing edge  39  of the guide post  23 . The fillet  35  extends from the trailing edge  39  of the guide post  23  toward the trailing edge  31  of the guide plate  24  and is tapered in thickness in that direction. 
       FIGS. 8 to 10  show a second embodiment of the invention, similar to the embodiment of  FIGS. 4 to 7  and like parts are given like reference numerals. In this embodiment, the web  29  of the previous embodiment is omitted. However, the thickness of the forward portion  32  is continued rearward past the trailing edge  39  of the guide post  23  and tapers down in thickness to a trailing edge  31 ′ which is thinner than the forward portion  32  to thus form on the trailing portion  30  of the guide plate  24  a trailing surface  36  which slants down toward the trailing edge  31 ′ of the guide plate  24 . The opposed lateral sides of the trailing surface  36  merge in the chamfer  34  provided on the forward and side portions  32 ,  33 . On the trailing portion  30  is formed a sticklike nose portion  30 a extending from the trailing surface  36  toward the trailing end  26  of the slider  20 . 
     Also shown in this second embodiment is the provision of fillets  40  between the upper side flanges  27  and the upper plate  21  to form an outlet mouth  35  at the trailing end  26  of the slider  20  which is tapered inwardly from the plane of the fastener coating layer  15  (the bottom edge of the side flange  27 ) towards the upper plate  23 . The fillets serve to guide the sealing lips of the slide fastener and may be shaped to match the upper surface of the sealing lips  11 . 
     Also seen in  FIG. 10  is a shallow platform  41  on the upper surface  42  of the lower plate  22 . The shallow platform  41  serves to help orient in a suitable direction the posture that the coiled coupling elements  10  assume when coupled, as known in the art. 
       FIGS. 11 and 12  show a third embodiment of the present invention. The third embodiment is similar to the second embodiment shown in  FIGS. 8 through 10 . So, parts which are similar to those of the second embodiment shown in  FIGS. 8 through 10  are also denoted by the same reference numerals in  FIGS. 11 and 12  showing the third embodiment. In the third embodiment, the trailing surface  36  formed on the trailing portion  30  of the guide plate  24  extends to the trailing edge  31  of the guide plate  24 . Furthermore, the trailing portion  30  tapers in width or lateral dimension towards the trailing end  26  of the slider  1 , thus presenting a wedge-like shape as a whole. This ensures that the sealing lips  11  can pass smoothly through the slider  1  during the movement of the slider  1 , thereby mitigating frictional resistance caused by the sealing lips&#39; sliding movement against the guide plate  24 . 
     Conclusions, Ramifications, and Scope 
     As above stated, since the slider is integrally formed, the slider can be strengthened, and in particular in the region between the upper plate and the guide plate where the slider parts are subject to greater separation forces as the slider is pulled along the fastener to urge the sealing lips together. This substantially reduces the cost of the production process and also leads to an improvement in product quality because of the avoidance of any misalignment or other errors which may arise in an assembly process. 
     Although the description above contains many specificities, these should not be construed as limiting the scope of the invention but as merely providing illustrations of some of the presently preferred embodiments of this invention. 
     Thus the scope of the invention should be determined by the appended claims and their legal equivalents, rather than by the examples given.