Abstract:
A plastic bag closer slider has a separator normally resting in notches in the tops of slider track strips, when the slider is at a bag-closed stop. As the slider is moved in the bag-opening direction, the separator is cammed downward by ends of the notches to disengage interlocking profile features and open the tag. In another embodiment, notches are omitted. The separator is manufactured with a normally down position but is resiliently biased upward when the bag is closed. As the slider is moved in the bag-opening direction, the pointed end of the separator wedge descends between the strips to open the bag. When the slider is moved in the bag-closing direction, the separator is cammed upward by the drag of the strip tops and the tapering walls of the slider squeeze interlocking profile features together, closing the bag.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates generally to reclosable plastic bags with closing zippers, and more particularly to zipper slider features thereof. 
     2. Description of the Prior Art 
     Various inventions have been made in the field of zipper-type closures for plastic bags. A problem encountered with some such closures has been the inadvertent separation of the slider from the bag. Another is unreliable opening or closing of the bag, and undue wear on certain features. To assist in the opening of some bags, some type of separator has been used. However, even when the bag is closed, the separator remains in place, enabling certain types of contents, such as powders and liquids, to spill out. One technique which has been used in an effort to overcome this problem, is to provide a notch in the tracks in which the separator can be received when the slider is at the bag-closing end of the tracks, thereby enabling the tracks to be completely closed without the separator maintaining a force in the tracks tending to open the bag. But the problem with such a notch is that it is difficult to make exactly the right length and depth, and it is difficult to install the slider exactly in place over the notch. If any of these elements occurs out of precise tolerance, then the slider will fail to operate properly. While some such efforts have been made in the slide tracks and slider to overcome such problems, the present invention is addressed to further improvement. 
     SUMMARY OF THE INVENTION 
     Described briefly, according to one embodiment of the invention, a flexible bag has a zipper-type closure with flexible strips attached to the bag walls, the strips having interlocking rib and groove profiles, and a slider. The slider is movable in one direction longitudinally of the strips to progressively separate the rib from the groove to open the bag, and is movable in the opposite direction to progressively return the rib to retained condition in the groove to close the bag. The slider has a separator normally situated in a rest position in the tops of the strips, when the slider is in a bag-closed stop location. As the slider is moved in the bag-opening direction, the separator pivots downward to disengage the interlocking profile features and open the bag. When the slider is moved in the bag-closing direction, the separator is cammed upward by the strip tops until it rides atop the strips, and the tapering walls of the slider squeeze the interlocking profile features together, closing the bag. A guide pin on the slider guides the slider to a desired point, without opening the bag. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a front elevational view of a reclosable plastic bag with a zipper assembly according to one embodiment of the present invention. 
     FIG. 2 is a top plan view thereof. 
     FIG. 3 is an enlarged section through the slider and track portion taken at line 3--3 in FIG. 2 and viewed in the direction of arrows and showing the slider in a bag-closed stop position. 
     FIG. 4 is a much-enlarged cross sectional view taken at line 4--4 in FIG. 2 and viewed in the direction of the arrows. 
     FIG. 5 is a top plan view of the bag assembly with the slider in position with the bag partially open. 
     FIG. 6 is a sectional view through the slider and track assembly taken at line 6--6 in FIG. 5 and viewed in the direction of the arrows. 
     FIG. 7 is a much-enlarged cross sectional view thereof taken at line 7--7 in FIG. 5 and viewed in the direction of the arrows. 
     FIG. 8 is a top plan view of the bag assembly with the slider in a bag partially-open position but with the slider moving to the right toward the bag-closed stop position. 
     FIG. 9 is a sectional view therethrough taken at lines 9--9 in FIG. 8 and viewed in the direction of the arrows. 
     FIG. 10 is a much-enlarged cross sectional view taken at line 10--10 in FIG. 8 and viewed in the direction of the arrows. 
     FIG. 11 is a sectional view taken at line 11--11 in FIG. 9 and viewed in the direction of the arrows to show the tapering walls of the slider. 
     FIG. 12 is a front elevational view of a reclosable plastic bag with a zipper assembly according to another embodiment of the present invention. 
     FIG. 13 is a top plan view of the FIG. 12 embodiment. 
     FIG. 14 is an enlarged sectional view taken at lines 14--14 in FIG. 13 and viewed in the direction of the arrows. 
     FIG. 15 is a further enlarged sectional view through the slider itself taken at the same cutting plane as FIG. 14 except with the slider separate from the bag as before installation on the bag. 
     FIG. 16 is a top plan view of the bag assembly of FIGS. 12 and 13 but with the slider in position with the bag partially open. 
     FIG. 17 is an enlarged sectional view through the slider and track assembly taken at line 17--17 in FIG. 16 and viewed in the direction of the arrows. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     For the purposes of promoting an understanding of the principles of the invention, reference will now be made to the embodiment illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended, such alterations and further modifications in the illustrated device, and such further applications of the principles of the invention as illustrated therein being contemplated as would normally occur to one skilled in the art to which the invention relates. 
     Referring now to the drawings in detail, a plastic bag 11 of conventional construction may be a sheet of polyethylene folded along the line 12 providing front and rear walls 13 and 14 (FIG. 4) sealed at the right-hand edge 16 and left-hand edge 17 by heat, ultrasonic or other type of sealing means. The marginal portions near the upper edges 13U and 14U are sealed by heat, ultrasonic welding or otherwise to base flanges 18B and 19B of elongated flexible plastic strips 18 and 19 at the front and rear bag walls. These strips are crimped and sealed at the right-hand end 18R and left-hand end 18L to the top of the bag and to each other. These strips which are typically made of extruded plastic have complementary profiles in which a portion of the rear strip 19 forms a groove 19G therein which interlockingly receives the rib 18P with flanged head 18H of an arrow-shaped cross section profile portion in strip 18. Since the groove is C-shaped, after the faces 18F and 19F are forced toward each other, forcing the head into the groove, the strips will remain together, with the groove resiliently holding the rib head snugly in the groove, sealing the bag closed. In this condition, the strip upper flange edges 18T and 19T (FIG. 10) touch each other and supplement the coupling of the rib head with the groove in providing a secondary closure of the top of the bag assembly. 
     Slider 21 is mounted on the strips 18 and 19. It includes a tunnel 22 of generally rectangular cross-sectional configuration extending lengthwise through it from an entrance end 23 to an exit end 24, the entrance and exit terminology referring to the relative direction of the track strip profile entering the entrance end 23 as the slider is moved to the right, and exiting end 24 as the slider is moved to the right in the direction of arrow 26 (FIG. 8) as the bag is closed. A slot 27 (FIGS. 4 and 11) in the bottom of the slider converges from the entrance end 23 to the exit end 24, as shown at 28 and 29 in FIG. 11. Likewise, the tunnel walls 31 and 32 converge in the same way between the entrance end 23 and exit end 24 of the slider. Therefore, as the slider is moved to the right in the direction of arrow 26, the open top of the bag is squeezed closed by the convergence of the walls 28 and 29 and 31 and 32 from the entrance end 23 to the exit end 24 of the tunnel. 
     As shown in FIG. 2, the top of the slider has an opening 33 therein that is partially closed by a separator tab 34 with a pointed portion 36 pointing in the same direction as walls 31 and 32 converge toward the exit end 24 of the slider. As shown in FIG. 5, the strip upper flanges have notches 37 and 38 therein. When the slider is in the bag-closed end stop position shown in FIGS. 1, 2, and 3, tab 34 projects into the notches and the pointed portion 36 extends down to a location touching the top 39 of the portion of the strip 19 profile which forms the groove 19G. A downwardly projecting guide post 41 in the slider extends down between the edges 18T and 19T. It serves two purposes. First of all, it very slightly spreads the edges of the slot near the entrance end 38E of the notch 38. It also serves as a stop to limit the movement of the slider in the bag opening direction of arrow 42, at the left-hand end where the bag is crimped at 18L so the slider will not slide off the end. Similarly it can serve as a stop at the right-hand end. 
     In the use of the assembly and starting with the bag closed as in FIGS. 1 through 4, the tab 34 is resting in the notch with its tip against the top 39 of the profile groove 19G portion. To open the bag, the slider is moved to the left in the direction of arrow 42. As it does so, the entrance edges 37E and 38E of the notches 37 and 38 in the upper flanges of the strips 18 and 19, are engaged by the sides of tab 34 and serve as cam surfaces which force the tab downward in the direction of arrow 43 to the position shown in FIGS. 5, 6 and 7, during which the point 36 is forced down on the top portion of the profile forming groove 19G and, sliding down on the curved surface 40 (FIG. 4) pushes that portion to the left in a direction away from the rib head 18H to separate these features as shown in FIG. 7 whereupon the bag is opened at this point. Further movement of the slider to the left in the direction of arrow 42 (FIG. 5) opens the rest of the bag top as shown at 46. When post 41 reaches the left-hand end of the bag where the strips 18 and 19 are crimped together, it stops the travel of the slider at that location. 
     To close the bag, the slider is gripped by the hand and pulled to the right in the direction of arrow 26 (FIG. 8). As it slides, engagement of the edges of the flanges 18T and 19T with the sides of the tab 34, tends to move the tab up in the clockwise direction of arrow 47 (FIG. 9) as the convergence of the tunnel walls 31 and 32 toward slider exit end 24 (FIG. 11) also squeezes the strips 18 and 19 together, such that the tab moves up to the location shown in FIGS. 9 and 10 where the point is riding on top of the upper inner edges of the flanges 18T and 19T, as shown in FIGS. 9 and 10. The tab will continue to ride in this position until the slider reaches the notch 38 at the bag-closed stop position of the slider, where the slider stops. At that point, the tab drops into the notch 38 to the position as shown in FIG. 3. 
     If the sound of the tab dropping into the notch is not sufficient to alert the user to stop pulling the slider, the fact that the slot 27 between slider walls 28 and 29 at the bottom of the slider extends inboard of the bottom edges 18L and 19L of the strips 18 and 19 to the base flanges 18B and 19B of the track strips, enables them to engage any abutment such as 18A or 19A which were formed at the end of each of the strips during the crimping closed thereof when the assembly is manufactured. Otherwise the pin 41 will stop the travel at the crimp of the upper edges 18T and 19T at the ends. 
     The disposition of the bottom slot walls 28 and 29 inboard of the outer bottom edges of the track strips at 18L and 19L, not only when the bag is closed, but also when the bag is open as in FIG. 7, prevents the slider from being pulled off the top of the strips and provides good vertical stability of the slider relative to the tracks at all times. 
     The material for the track strips is typically an extruded low density polyethylene. The material for the slider is typically a molded HMW plastic. 
     As indicated above, it is desirable that the tab 34 have a predisposition to descend into the notches 37 and 38 when the slider is moved into the bag-closed stop position shown in FIGS. 1-4. If the slider is molded in one step, with the tab 34 co-planar with the rest of the top of the slider, it may require a special molding technique to establish the predisposition for it to descend into the notch. It is also possible to mold the slider in two parts, with the tab being integral with the right-hand part and the opening 33 molded into the left-hand part, followed by ultrasonically or otherwise welding the two parts together. In this situation, the tab could be molded or separately attached such as to project downward into the notch or even into the space between the complementary rib and groove 18P and 19G as shown in FIGS. 6 and 7. The stop post 41 may be of metal or plastic driven into or through or molded or adhesively secured to the underside of the tunnel roof where shown in FIG. 3. 
     Referring now to FIGS. 12 through 17, components which are identical to or very similar to those in FIGS. 1 through 11 are given the same reference numerals but with a prefix &#34;1&#34;. In this example, the bag 111 is like bag 11 except that the elongated flexible plastic strips 118 and 119 do not have the notch 38 in the top thereof. This is evident upon comparison of FIG. 5 with FIG. 16, and FIG. 6 with FIG. 17. Also, slider 121 is different in the respect that, in this embodiment, it is molded with the wedging tab 134, 136, perpendicular to the top of the tunnel, as shown in the sectional view of FIG. 15. The post 141 may be made and mounted as described for post 41. The material of the slider, being flexible and somewhat resilient, enables the tab 134, 136 to be resiliently pushed upward in the direction of arrow 147 to the position shown in FIG. 14 and dotted in FIG. 16, as the slider is moved in the bag-closing direction of arrow 126 (FIG. 16). When the tab is in this position, the tip of it rests atop the upper edges 118T and 119T of the strips 18 and 19, as shown for the previously described embodiment in FIG. 10. The side edges of the point converge in the same, bag-opening direction as slider walls 131 and 132, toward the exit end 124 of the slider. It is preferable that, as in the previously described embodiment, the post 141 not resiliently bend but, instead remain in the position shown in FIG. 14 between edges 18T and 19T, so it typically would be made of metal pressed into position through the top of the slider. 
     In this embodiment of the invention, when the slider is moved to the left in the bag-opening direction of arrow 142 from the bag-closed position shown in FIG. 13, and although the tab 134, 136 may be resting atop the top flanges 18T and 19T, it is stressed out of its normal molded unstressed position shown in FIG. 15 and tends to move downward. Therefore, with this and the point on the tab portion 136, it descends down between the upper flanges in the direction of arrow 143 and continues to push down to open the bag as in the previously described embodiment where the tab is cammed downward by the notch edges. This latter embodiment is the preferred embodiment because the guide strips 18 and 19 are easier to manufacture without the notch, enabling higher production and less scrap. Also, when the slider is moved in the direction of arrow 126 to the closed position, it can move completely out of not only the space between the tongue and groove 18H and 19G (FIG. 4), but also out of the space between the upper flanges to the position as shown in FIGS. 10 and 14. 
     While the invention has been illustrated and described in detail in the drawings and foregoing description, the same is to be considered as illustrative and not restrictive in character, it being understood that only the preferred embodiment has been shown and described and that all changes and modifications that come within the spirit of the invention are desired to be protected.