Abstract:
A fastener for plastic bags opened and closed by a slider includes first and second track members with each having one of a pair of interlocking profiles. The fastener has opposite ends with terminations. A slider is mounted on the fastener and has a separation member with a wide portion and a narrow portion positioned in the fastener. The slider, upon complete closure of the fastener, rides up onto a termination moving the wide portion of the separation member out from between the fastener allowing the profiles to lock along the entire length of the fastener.

Description:
FIELD OF THE INVENTION 
     The present invention relates generally to fasteners for plastic bags that are opened and closed by a slider, and, more particularly, to leak resistant fasteners. 
     BACKGROUND OF THE INVENTION 
     Plastic bags are a popular household item used for a variety of uses such as storage of food. The addition of reclosable fasteners or zippers to these bags has further enhanced their utility and the addition of a slider has made the fasteners easier to open and close. 
     Although sliders have made opening and closing the fasteners easier, some of the slider operated fasteners have leakage across the fastener when the fastener is closed. This is caused by a separation member or finger on the slider that extends between sides of the fastener. Even when the fastener is completely closed, a portion of the separation member extends into the fastener preventing closure of the fastener at that location. One solution to this leakage has been to remove a portion of a fastener track at the location of the slider in the fastener closed position. When the slider is in this location, the separation member is in this portion of the fastener track and the fastener is completely closed. Precise sizing and locating the removed portion is difficult and failure to remove the correct amount and in the correct location can result in leaking and possible operation failure of the slider. 
     Another solution to the problem of leakage is a slider with a pivoting separation member. When the slider is moved to close the fastener, the separation member pivots out of the fastener. When the slider is reversed to open the fastener, the separation member pivots down into the fastener. An example of this slider is disclosed in U.S. Pat. No. 5,871,281. These sliders are complex to design and manufacture and are costly. In addition, the fact that the separation member must pivot to operate impacts the reliability of the slider. There is a need for a low cost, highly reliable slider and reclosable fastener arrangement that is leak resistant. 
     SUMMARY OF THE INVENTION 
     The present invention is directed to a slider that when used to open and close a fastener on a plastic bag provides a leak resistant closure. The slider has a top, depending side walls, a front or nose portion with a ramp on the nose portion, a rear portion, and a separation member or finger formed on the underside of the top extending from the nose portion toward the rear portion. The ramp can instead be incorporated into the shape of the separation member. The leak resistant feature is accomplished by withdrawing the operable portion of the separation member from cooperating features of the fastener. The separation member has a wide portion and a narrow portion. The fastener includes a pair of tracks and each track has an interlocking profile. Each track has two ends with a termination on each end. As the slider closes the fastener, the wide and narrow portions of the separation member move within the fastener with the wide portion holding the profiles open. As the slider is moved to close the fastener, the fastener passes along the separation member from the wide portion to the narrow portion and this along with body of the slider moves the profiles together interlocking the profiles. This action is reversed during the fastener opening movement of the slider. One example of this opening and closing is described in U.S. Pat. No. 5,007,143 which is incorporated by reference herein. When the slider reaches the termination at the end of the fastener, the ramp on the slider engages and travels up the termination. As this occurs, the slider is pivoted up which moves the wide portion of the separation member out of from between the fastener allowing the profiles to interlock up to the termination. The shape and positioning of the ramping surfaces and the relative location of slider retention shoulders control the change in orientation of the slider and the stiffness of the fastener is also a factor. The ramp can include a lock such as an indention which snap locks onto the termination and reduces the likelihood of the slider accidently being moved to open the fastener enough to allow leakage. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Other objects and advantages of the invention will become apparent upon reading the following detailed description in conjunction with the drawings in which: 
     FIG. 1 is an enlarged perspective view of a slider constructed in accordance with the principles of the present invention; 
     FIG. 2 is a side elevation view of the slider illustrated in FIG. 1, 
     FIG. 3 is a front view of the slider on a fastener; 
     FIG. 4 is a cross sectional view of the slider and fastener of the present invention in the fastener closed configuration; 
     FIG. 5 is a side elevation view of the slider and fastener with the slider locked on an end termination clip; 
     FIG. 6 is a view similar to FIG. 5 with the slider on an terminal end of the fastener; 
     FIG. 7 is a perspective view of an alternative embodiment of the slider; 
     FIG. 8 is a cross sectional view of an alternative embodiment of a fastener slider arrangement; 
     FIG. 9 is a partial cross sectional view of a fastener slider arrangement illustrating the forces on and action of the slider during parking; 
     FIG. 10 is a cross sectional view of a slider on a fastener; and 
     FIG. 11 is a cross sectional view of a slider on a fastener illustrating the reaction of the slider and fastener during parking of the slider. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring initially to FIG. 1, there is illustrated a slider  10  that when combined with a fastener  12  (FIGS. 4 and 5) eliminates the need for a slider parking notch to provide a leak resistant closure of the fastener  12 . A parking notch is a notch cut in the tracks of prior art fasteners in which a slider is located in a fastener closed position such that a separation finger on the slider is out of engagement with tracks on the fastener allowing the fastener to be fully closed. As will be described in detail hereinafter, the need for a parking notch is eliminated by docking or parking the slider  10  on an fastener end termination such as an end termination clip  14  (FIG. 5) which lifts at least a portion of a separation finger or member  16  (FIG. 3) on the slider  10  out from between the fastener  12  allowing complete closure of the fastener  12 . 
     To understand how a leak resistant fastener and slider arrangement is accomplished reference is first made to the slider  10  (FIGS.  1 - 3 ). The slider  10  is of the type described in U.S. Pat. No. 5,007,143 and this patent is incorporated by reference in its entirety. The slider  10  includes a top  18  with a forward portion or nose  20  and a rear portion  22 . A pair of sides or side walls  24  and  26  depend downwardly from the top  18 . At the lower end of each side wall  24  and  26  are shoulders  28  and  30  (FIGS.  3  and  4 ), respectively, which cooperate with the separation finger  16  to assist in opening and closing the fastener  12 . 
     The nose  20  of the slider  10  extends forward of the top  18  and has an inclined ramp  32  on the front under side of the nose  20 . An indention or lock  34  (FIG. 2) is formed on the under side of the slider nose  20  behind the ramp  32 . The lock  34  snaps onto an enlarged end  36  of the termination clip  14  after the ramp  32  has passed over the end  36  in the fastener closed position (FIG.  5 ). 
     The separation finger  16  has a first wide portion  40  (FIG. 3) and a second narrow portion  42  (FIG.  4 ). The separation finger  16  with the first and second portions  40  and  42  interact with first and second portions  44  and  46  (FIGS. 6 and 7) of the fastener  12  to lock and unlock first  48  and second  50  profiles on the fastener  12  thereby opening and closing the fastener  12  in the manner described in U.S. Pat. 5,007,143. More specifically, the wide portion  40  of the separation finger  16  in cooperation with the shoulders  28  and  30  spread the first and second portions  44  and  46  which separates the first and second profiles  48  and  50  thereby opening the fastener  12  (FIG. 6) as the slider  10  is moved. To close the fastener  12 , the slider  10  is moved in the reverse direction and the narrow portion  42  of the separation finger  16  cooperates with the shoulders  28  and  30  and the sides  24  and  26  of the slider  10  to bring the first and second portions  44  and  46  together which brings together and locks the first and second profiles  48  and  50  (FIG.  7 ). 
     To close the fastener  12  completely, at least the wide portion  40  of the separation finger  16  is removed from between the first and second portions  44  and  46 . This is accomplished by docking or parking the nose  20  of the slider  10  on the end  36  of the termination clip  14  (FIG.  5 ). As the slider  10  closes the fastener  12  and approaches the termination clip  14 , the ramp  32  engages the end  36  of the clip  14  causing the nose  20  and that end of the slider  10  to rock or rotate upwardly in the direction of the arrow  52  in FIG.  5 . As this action occurs, the wide portion  40  of the separation finger  16  is moved up and out from between the fastener portions  44  and  46 . Since only the narrow portion  42  of the separation finger  16  is between the first and second portions  44  and  46 , the first and second profiles  48  and  50  lock along the entire length of the fastener  12  up to the termination clip  14 . Upon complete closure of the fastener  12 , the slider  10  is locked on the termination clip  14  by the lock  34  snapping onto the end  36  of the termination clip  14  (FIG.  5 ). 
     To open the fastener  12 , the slider  10  is grasped and moved away from the termination clip  14 . As the slider  10  begins to move, the lock  34  moves off of the end  36  of the termination clip  14  and the ramp  32  slides over the end  36 . As this occurs, the wide portion  40  of the separation finger  16  moves between the first and second fastener portions  44  and  46  to separate the first and second profiles  48  and  50  and open the fastener  12 . 
     Although the fastener  12  is terminated by a clip  14  in the embodiment illustrated in FIGS. 1-5, other forms of terminating the ends of the fastener  12  will also provide the desired result. For example, FIG. 6 illustrates a fastener  112  that is terminated by an end weld  114 . The end weld  114  may be formed by heated bars pressed against the end of the fastener  112 , ultrasonic welding or other ways known in the art. As the slider  10  approaches the end weld  114 , the wide portion  40  of the separation finger  16  encounters increased resistance as it attempts to spread the first and second fastener portions  44  and  46  which are tightly bound in a closed configuration by the end weld  114 . The convergence of the first and second fastener portions  44  and  46  behind the separation finger  16  and the transition into the end weld  114  form a natural ramp on which the ramp  32  and nose  20  of the slider  10  ride. This action rocks the slider  10  in the direction of the arrow  119  (FIG. 6) moving the wide portion  40  of the separation finger  16  from between the first and second fastener portions  44  and  46  as in the embodiment of FIGS. 1-5. This action is reversed as the slider  10  is pulled away from the end weld  114  to open the fastener  112 . 
     If desired, the nose  20  with the ramp  32  can be eliminated from the slider  10 . Such a slider  110  is illustrated in FIG.  7 . Except for a nose and ramp, the slider  110  is identical to slider  10 . Both the sliders  10  and  110  function to close a zipper  12  completely. As each slider  10  and  110  approaches a zipper end termination  14  or  114 , an elastic twisting deformation of the zipper profiles  48  and  50  occurs. The deformation is caused by abrupt change in the orientation of the profiles  48  and  50  from spread apart to interconnected. The deformation of the profiles by the slider  10  or  110  increases the magnitude of the reaction force against the separation finger  16 . The deformed profiles  48  and  50  form a ramp which shifts the contact point with the slider  10  or  110  resulting in a reaction force with an upward component in the direction of arrow  112  (FIGS.  8  and  9 ). This upward force causes a rotational moment  114  (FIGS. 9 and 11) on the slider  10  or  110  about the shoulders  28  and  30  in a direction that lifts the separation finger  16  out from between the profiles  48  and  50 . Referring to FIG. 9, the distance D between the upward reaction force  112  to the shoulders  28  and  30  affects the magnitude of the moment indicated by the arrow  114  acting to lift or disengage the separation finger  16  from the profiles  48  and  50 . 
     Lifting of the separation finger  16  occurs due to a clearance  116  (FIG. 10) between the slider  110  or  10  and the profiles  48  and  50 . A shown in FIG. 9, the upward reaction force  112  rotates the slider  10 ,  110  relative to the fastener  12  to the extent allowed by the clearance  116 . Because the slider  10 ,  110  is rigid, additional relative motion, if required, will only occur through elastic deformation of the portion of the profiles  48  and  50  within the slider  10 ,  110 . The beam stiffness of the profiles  48  and  50  and the unsupported lengths D 1  and  116  (FIG. 11) determine how much force is required to lift or move the separation member  16  out of the profiles  48  and  50 . This rocking of the slider  10 ,  110  can be accomplished by the engagement of the ramp  32  with the end termination  14 ,  214  or the weld  114 . 
     While the present invention has been described with reference to one or more particular embodiments, those skilled in the art will recognize that many changes may be made thereto without departing from the spirit and scope of the present invention. Each of these embodiments and obvious variations thereof is contemplated as falling within the spirit and scope of the claimed invention, which is set forth in the following claims.