Abstract:
A self-aligning zipper seal module adapted for quick change-out in a sealing carriage. The zipper seal module allows for a quick modification of a sealing carriage in order to accommodate different package dimensions. The module is stored and is installed in a closed and aligned position by use of an aligning handle. The module is easily installed or removed with a single tool and is designed to reduce the potential for operator injury by isolation from heat sources and by virtue of the aligning handle. The various seal facings of the module are oriented to equalize pressure on the facings during sealing and increase stripping efficiency. The zipper seal facings incorporate a novel insert design, thereby eliminating the need for stocking different sized facings to accommodate various bag widths. A return module of similar design is used to quickly return the sealing carriage to a standard configuration.

Description:
BACKGROUND OF THE INVENTION 
     1. Technical Field 
     The present invention relates to a reclose or zipper seal jaw design for use in a sealing carriage of a vertical form and fill packaging machine, and, in particular, to a quick-change, reclosable zipper seal jaw module and standard or “return” module that can accommodate variable bag sizes. The modules are self-aligning, easily installed on existing bridge assembly hardware, and incorporate several safety enhancements. 
     2. Description of Related Art 
     Vertical form, fill, and seal packaging machines are commonly used in the snack food industry for forming, filling, and sealing bags of chips and other like products. Such packaging machines take a packaging film, such as polypropylene, from a sheet roll of said film, and forms the film into a vertical tube around a product delivery cylinder. The vertical tube is vertically sealed along its length to form a back seal. The machine applies a pair of heat-sealing jaws or facings against the tube to form a transverse seal. This transverse seal acts as the top seal on the bag below and the bottom seal on the package being filled and formed above. After the seal has been formed, the film tube is pushed downward to draw out another package length. The package below the transverse seal is separated by cutting across the sealed area. 
     Before each transverse seal is formed by the sealing jaws, the product to be packaged is dropped through the product delivery cylinder and formed tube and is held within the tube above the bottom transverse seal. Prior to forming the upper transverse seal, the sealing jaws are brought together in two steps. First, a pair of stripping plates or bars are brought into contact with the film in order to flatten the tube and strip product out of the area to be sealed. Second, the final closing movement of the jaws is performed, thereby forming the transverse seal. 
     The bag sealing functions of a vertical form, fill, and seal machine are best described with reference to FIGS. 1 a  and  1   b.  FIG. 1 a  shows a sealing carriage on a prior art form, fill, and seal packaging machine. FIG. 1 b  is a cross-section of a prior art facing assembly installed in said carriage. Opposed transverse seal jaw facings  102 ,  104  (hereinafter referred to by Applicants as “jaw facings”) are shown attached to opposed bridge assemblies  106 ,  108 . Behind each jaw facing  102 ,  104  is a heat probe  128 ,  130  capable of heating the exposed surface of the jaw facings up to 405° F. during operation. Placed between the jaw facings  102 ,  104  and their respective bridge assemblies  106 ,  108  is a heat separator  136 ,  138 . The heat separators  136 ,  138  provide a thermal barrier between the jaw facings  102 ,  104  and the bridge assembly  106 ,  108  in order to minimize heat transfer to the bridge assembly  106 ,  108  and other components attached thereto. A thermocouple or thermoster  132 ,  134  is placed between the heat separator  136 ,  138  and the heat probe  128 ,  130  in order to monitor the jaw facing  102 ,  104  temperature. As previously described, a transverse seal is formed when a tube of film placed between the jaw facings  102 ,  104  is flattened as the jaw facings  102 ,  104  are brought in close proximity to each other. This is accomplished by both bridge assemblies  106 ,  108  traversing towards each other while riding on two stationary rods  110 ,  112 . 
     Also shown attached to the bridge assemblies  106 ,  108  are a pair of opposed crumb plates  114 ,  116 . When the bridge assemblies  106 ,  108  are brought together, the crumb plates  114 ,  116  slightly overlap, thereby forming a temporary “S” shaped constriction in the flattened film tube. This “S” shaped constriction provides a means for keeping product out of the transverse seal area while the tube of film above the constriction is filled with product. Two stripper bars  118 ,  120  are also shown attached to the bridge assemblies  106 ,  108 . The stripper bars  118 ,  120  are typically spring loaded and provide the stripping function previously described. 
     Both of the jaw facings  102 ,  104  are constructed with a central channel  141 ,  143  to accommodate a knife or cutting tool  122 . This knife  122  is recessed within the channel  141  of one of the jaw facings  102  and held in place by two knife brackets  124 ,  126  attached to the bridge assemblies  106 ,  108 . After the transverse seal has been formed on the flattened film tube, the knife brackets  124 ,  126  are rotated slightly, thereby exposing the knife  122  to the transverse seal. This action cuts the transverse seal, thereby completing the process of forming, filling, and sealing a single package. 
     The prior art carriage described above is designed such that the jaw facings  102 ,  104  can be removed in order to install jaw facings  102 ,  104  that provide for different vertical widths of the resultant transverse seals. The facing assembly shown in FIG. 1 b  is aligned at the factory, and removal from the sealing carriage by the operator of more than the jaw facings  102 ,  104 , crumb plates  114 ,  116 , and stripper bars  118 ,  120  is not recommended. Such design is also not easily adapted to the formation of a zipper seal along with the standard transverse seal. In fact, as will be explained below, a form, fill, and seal packaging system must be substantially modified when it is used to install a zipper seal at the top of the package. 
     A zipper seal is a resealable barrier that can be installed on the top end of a bag either immediately below or above the upper transverse seal. After the consumer breaks the upper transverse seal to gain access to the product within the package, the zipper seal can be reclosed, thereby keeping the product fresh. Such package is referred to as a “reclose” bag. Consequently, the terms “zipper seal module” and “reclose module,” and many other descriptive terms using as adjectives the words “zipper” or “reclose,” are used herein by Applicants interchangeably. 
     FIGS. 2 a  and  2   b  show one embodiment of a reclose food package  281  incorporating a zipper seal  283 . FIG. 2 a  is a perspective view of a flexible, plastic package or bag  281  used to contain potato chips, tortilla chips, and the like. FIG. 2 b  is a cross-section of the top of said bag  281 . The food package  281  shown is typical in that it has an upper transverse seal  285  and a lower transverse seal  287 . However, this bag also uniquely incorporates a zipper or reclose seal  283  immediately below the upper transverse seal  285 . The zipper seal  283  is made up of a male engagement member  291  and a female engagement member  289 . 
     For the embodiment illustrated, the package  281  is opened for the first time by pulling on the exterior walls of the package  281  below the zipper seal  283 . The two opposed members  289 ,  291  separate, thereby opening the zipper seal  283 . Stress can then be exerted on the upper transverse seal  285  until it opens. Once this occurs, the package  281  is fully opened and the product, such as tortilla chips  293 , may be consumed. The package  281  can then be resealed by applying pressure to the exterior of the package  281  along the zipper seal  283 , thereby forcing the male engagement member  291  back into the female engagement member  289 . This novel reclose bag design is described in detail in U.S. patent application Ser. No. 09/079,382 filed on May 15, 1998 now U.S. Pat. No. 5,972,386. 
     When making the reclose bag  281  illustrated, the opposed members  289 ,  291  (of the zipper seal  283 ) must be heat sealed to the inside surface of the food package  281 . Further, these opposed members  289 ,  291  must be heat-sealed together at each end  295 ,  297 . This is accomplished by applying a heat and pressure sealing device to an outer areas of the zipper seal  283 . 
     The film that enters a form and fill machine to form the reclose package  281  shown in FIG. 2 a  is typically a continuous sheet with graphics presented on one side. The side of the sheet on which the graphics are presented will ultimately comprise the outside of the package  281 . The unprinted side of the sheet will ultimately comprise the inside of the package  281 . Prior to entering the form and fill machine, zipper seals  283  must be attached to the inside film surface by securing one of the opposed members  289 ,  291  on the inside surface of the film with the zipper seal  283  in the closed configuration position. The zipper seal  283  thus secured should be oriented such that when the upper transverse seal  285  is formed on the package  281 , the zipper seal  283  is located in its proper position below and parallel to the upper transverse seal  285 . This will allow for the formation of both the transverse seal  285  and the permanent attachment of the zipper seal  283  to the inside of the package  281 . The simultaneous formation of the transverse seal  285  and the installation of the zipper seal  283  can be accomplished with an extensively modified prior art sealing carriage, in part by installing a second set of facings for sealing the zipper seal into the package along with the existing set of facings. As will be described, such adaptation of an existing form and fill sealing carriage makes for a number of technical difficulties and unsatisfactory results. 
     FIGS. 3 a  and  3   b  illustrate one prior art embodiment known to Applicants of a modification of a sealing carriage to accommodate the formation of a reclose bag. FIG. 3 a  is a perspective view of a modified sealing carriage, while FIG. 3 b  is a cross-section of the modified facing assembly. By comparing FIGS. 3 a  and  3   b  with FIGS. 1 a  and  1   b,  it is evident that a second set of opposed facings  340 ,  342  have been installed below the first opposed set of facings  302 ,  304 . The second set of opposed facings  340 ,  342  are the means for sealing the zipper below the transverse seal on the reclose bag. Consequently, they are known as zipper seal jaw facings  340 ,  342  and referred to herein by Applicants as “zipper seal facings.” The stripper bars  318 ,  320  are now attached below the zipper seal facings  340 ,  342 . Each of the zipper seal facings  340 ,  342  must also have a respective heat probe  344 ,  346  and thermosters  348 ,  350 . 
     Prior art modifications to the sealing carriage of a form and fill packaging system to accommodate the manufacture of reclose bags are not easily installed, have exhibited poor performance characteristics, raise several safety concerns, and are only suitable for one package size and zipper configuration. Consequently, the modification shown in FIGS. 3 a  and  3   b  is not a desirable fix. As will be explained, the purchase of a dedicated form and fill machine only capable of constructing reclose bags is also not an acceptable alternative. 
     By way of background, most chip packaging facilities have on-site one to several (and perhaps as many as seven or eight) vertical form, fill, and seal packaging machines. A single packaging facility might be required in any given week to package several different product lines in numerous different bag sizes for each product line by using the same form and fill packaging machines. Each form and fill packaging machine is quite expensive, for example, in the range of $50,000 to $150,000, and represents a large capital investment. Consequently, it is critical to the economic efficiency of the packaging facility that each form and fill machine be capable of being quickly adapted to handle a variety of bag widths and lengths. This is easily done with the prior art vertical form, fill, and seal machine discussed herein for standard (non-reclose) bags. The facings  102 ,  104  (shown in FIG. 1 a ) can accommodate any required bag width up to the total width of the facings  102 ,  104 . The bag length is easily adjusted by changing the amount of film travel below the facings  102 ,  104 . However, converting a prior art vertical form, fill, and seal machine from the configuration shown in FIGS. 1 a  and  1   b  to the configuration shown in FIGS. 3 a  and  3   b  requires extensive modifications to the machine to allow for additional attaching points, electrical connections, controls, and to accommodate additional stripper travel. Once these modifications are made, it typically takes several hours to install the additional set of facings and accompanying heat probes, stripper plates, and other required items. It then takes an additional several hours to reconvert the assembly back to a standard transverse seal configuration. 
     It is expected that a typical packaging facility will only need to dedicate a small portion of the packaging assets to the formation of reclose bags incorporating zipper seals. Consequently, a permanent changeover to a reclose bag configuration or the use of a specifically built reclose bag machine would result in such packaging machine sitting idle for long periods of time. The ability to quickly change over from a standard transverse seal configuration to a reclose configuration is, therefore, a major consideration. The present down-time involved in changing from one configuration back to the other, which is in excess of several hours, adds considerably to the labor costs in running reclose bags and reduces the overall packaging capacity of any single packaging facility. 
     Along the same lines, prior art reclose designs allow for the production of only one bag width for any given set of zipper seal facings  340 ,  342 . This is due to the fact that the zipper seal facings  340 ,  342  have a rectangular shaped recess in order to accommodate the zipper seal while at the same time sealing the zipper seal at each end and around its edges to the inside of the bag. If a change in bag size is required for a reclose bag, the zipper seal facings  340 ,  342  must be removed from the reclose assembly and replaced with a new zipper seal facing  340 ,  342  to accommodate the new bag&#39;s width. This again takes two to four hours to accomplish, thereby requiring additional man hours and reducing the efficiency of the packaging facility. The zipper seal facings  340 ,  342  are also expensive items, presently costing approximately $7,500.00 per each set of facings  340 ,  342 . Capital investment must therefore be made for every conceivable bag width so that a specific sized zipper seal facing  340 ,  342  can be on hand whenever a corresponding bag width needs to be run on the form and fill machine in the reclose configuration. 
     The need to replace components on the modified carriage and facing assemblies shown in FIGS. 3 a  and  3   b  increases the safety hazards involved in such change over operation. In order to remove or install the zipper facings  340 ,  342  and related components, it is necessary to bring the carriage to the open position. An inadvertent activation of the closing feature of the carriage while an operator is attempting to remove or install a component could result in serious injury. Further, during operation the various facings  302 ,  304 ,  340 ,  342  are heated to 350° F. In order to remove the facings  302 ,  304 ,  340 ,  342  after operation, they must either be allowed to cool or careful attention must be paid to insure that the operator is not burned by the facings  302 ,  304 ,  340 ,  342  or accompanying heat probes  328 ,  330 ,  344 ,  346 . The cutting knife  122  is also extremely sharp and must be carefully removed. 
     The placement of the zipper seal facing  340 ,  342  below the standard jaw facing  302 ,  304  also introduces several problems. It can be seen from FIGS. 2 b  and  3   b  that the area that is required to be stripped of product prior to applying both a standard transverse seal and a reclose seal is approximately doubled in length compared to the area that requires stripping when only a transverse seal is formed. More importantly, with the zipper seal  283  located below the transverse seal  285 , the zipper seal  283   b  is closest to the product and will always have to be stripped even if portions of the transverse seal  285  do not require stripping. This is problematic in that the zipper seal  283  is significantly thicker than the transverse seal  285 . Effective stripping widths for a transverse seal  285  are on the order of 0.030 inches, while effective stripping widths for a zipper seal  283  are on the order of 0.125 inches. Consequently, stripping efficiency of the transverse seal area is lost because the strippers must be set to accommodate the thicker zipper seal  283  located below. Further, the chassis or frame of the form and fill machine must be modified to allow space for stripping in light of the addition of components below the existing facings and accompanying stripper bars. The alternative is to limit the amount of stripping travel, which in turn limits the ability to remove product from the sealing areas. 
     It is also evident that the zipper seal facings  340 ,  342 , unlike the jaw facings  302 ,  304 , are not centered along the axis of the closing force acting on the carriage. FIG. 3 b  shows two force vectors F indicating that the force exerted on the assembly is centered along the axis of travel of bridge assemblies  306 ,  308  along the stationary rods  310 ,  312 . These force vectors typically produce a pressure of 1000 to 1200 psi along the facings  302 ,  304  during seal formation. However, the rigidity of the facing assembly shown in FIG. 3 b  is not sufficient to equally distribute this pressure because of the cantilevered location of the zipper seal facings  340 ,  342  away from the centerline of the supporting bridge assemblies  306 ,  308 . The zipper seal facings  340 ,  342  act as lever arms rotating away from the force F centered on the bridge assemblies  306 ,  308 . Unless this phenomena is counteracted, sufficient pressure cannot be applied on the zipper seal to adequately and uniformly attach it to the inside of the bag. A prior art fix to this problem is to install springs (not shown) behind the zipper seal facings  340 ,  342  in order to counteract the rotating effect. This fix has been demonstrated to reduce the overall pressure applied by the carriage assembly on the bag film. To counteract this loss of pressure, the heat or the dwell time must be increased, or both. Increasing the dwell time reduces the productivity of the bag maker, while heat can only be increased to a certain level before other adverse consequences are experienced. 
     Consequently, a need exists for a modular zipper seal jaw unit that can be easily removed from or installed on a prior art form and fill packaging machine sealing carriage, thereby quickly modifying the sealing carriage for a reclose configuration. This zipper seal jaw module should incorporate safety features to keep the operator away from heat sources and should physically lock in the closed position in order to avoid inadvertent closure of the device on the operator&#39;s hands during removal or installation. Ideally, the module should be self-aligning and quickly installable with a minimal number of tools. The module design should allow for a uniform application of pressure during the sealing mode between the jaw facings and the zipper seal facings. Further, the orientation of the module should allow for no interference with the form and fill machine chassis during stripping and promote increased stripping efficiency. A single module should be easily convertible to handle any width reclose bag without the need to stock and replace various sizes of zipper facings. The invention should also incorporate a standard return module that can be quickly and easily substituted for the reclose module to return the form and fill package machine to standard transverse seal operation. 
     SUMMARY OF THE INVENTION 
     The proposed invention comprises a quick-change zipper seal jaw module and accompanying return module that are self-aligning and easily installed in less than fifteen minutes with a single standard tool. The zipper seal module uses two rigid support members to support an opposed pair of zipper seal facings and an opposed pair of jaw facings. The support members can also support crumb plates and stripper bars, as needed. Each support member is easily attached to an existing bridge assembly with one or more bolts. Each support member also has at least one threaded receiver for receiving a bolt from an aligning tool. This aligning tool holds the opposed facings together in an aligned position when the module is being installed, removed, or while in storage. The heating requirements of the module are completely self-contained and connected to electrical quick-connect plugs which mate with quick-connect outlets installed on the chassis of the form and fill machine. 
     The zipper facings are located above the jaw facings in one embodiment of the invention. This requires that the package film be run upside-down, but also increases stripping efficiency, since the thicker zipper seal is located further from the product level in the bag during sealing. Further, the zipper seal facings and jaw facings are oriented such that the pressure applied on the module by the bridge assemblies during a sealing step is generally distributed equally about all facing contact surfaces. A knife adapter is provided to move the location of the knife to the repositioned jaw facings. 
     In one embodiment of the invention, the zipper seal facing is constructed of a slotted channel that allows for the installation of end inserts. This allows for the same zipper facing to be used to make varying widths of reclose bags by merely changing the size of the end inserts or moving the inserts relative to each other within the slotted channel. 
     The invention also provides for a “return” module which returns the vertical form, fill, and seal machine to a standard transverse seal configuration using the same mounting hardware as used with the reclose or zipper seal module. The return module is also self-aligning by use of an alignment handle. 
     The invention is a great improvement over the prior art for a number of reasons. The time involved in changing a form and fill machine from a standard transverse seal configuration to a reclose configuration has been reduced from several hours to less than 15 minutes. A similar time saving is involved when adjusting the zipper seal facing of the invention for varying bag widths since the zipper seal facing need not be removed. This feature also saves a considerable amount of capital investment, since changing a reclose bag width does not require the use of a different, and expensive, size jaw facing. 
     The use of an aligning handle with both the reclose module and return module greatly increases safety during change-over operations and when required maintenance must be performed. Since the module is completely self-contained, maintenance on heat probes, thermosters, and other module components can be done off-line and away from the potential crushing hazards associated with working on sealing carriage components while the sealing carriage is in the open position. Changing facings can also be done off-line. The modular installation and removal using the aligning handle is done with the sealing carriage in the closed position, thereby keeping an operator away from hot components immediately after operation and reducing the chance of the facings inadvertently closing on an operator&#39;s hand. 
     The invention performs the sealing function more efficiently than prior art designs and increases stripping efficiency due to the reversed and centered relative orientation of the jaw facings and zipper seal facings. Normal dwell times and temperatures can be used while still producing uniform and acceptable transverse seals and zipper seals. The orientation of the facings centered on the bridge assembly also adds minimally to the vertical space required below the bridge assemblies to accommodate stripping travel. Therefore, the modules do not interfere with an existing form and fill machine chassis during the stripping phase of package formation. 
     The above as well as additional features and advantages of the present invention will become apparent in the following written detailed description. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The novel features believed characteristic of the invention are set forth in the appended claims. The invention itself, however, as well as a preferred mode of use, further objectives and advantages thereof, will be best understood by reference to the following detailed description of illustrative embodiments when read in conjunction with the accompanying drawings, wherein: 
     FIG. 1 a  is a perspective view in elevation of a prior art sealing carriage; 
     FIG. 1 b  is a cross-section of a prior art facing assembly; 
     FIG. 2 a  is a perspective representation of a food package incorporating a zipper seal; 
     FIG. 2 b  is a cross-section of the top portion of a food package incorporating a zipper seal; 
     FIG. 3 a  is a perspective view in elevation of a prior art modification to a sealing carriage to accommodate a reclose configuration; 
     FIG. 3 b  is a cross-section of a prior art modification to a facing assembly to accommodate a reclose configuration; 
     FIG. 4 a  is a perspective view in elevation of the reclose module of the present invention installed on a prior art sealing carriage; 
     FIG. 4 b  is a cross-section of the reclose module of the present invention; 
     FIG. 5 is a perspective view in elevation of the reclose module of the present invention with an aligning handle installed; 
     FIG. 6 is a perspective view in elevation of the aligning handle of the present invention; 
     FIG. 7 is a perspective view in elevation of one embodiment of a zipper seal facing of the present invention; 
     FIG. 8 is a perspective view in elevation of the knife assembly of the present invention; 
     FIG. 9 is a cross-section view of the return module of the present invention; and 
     FIG. 10 is a perspective view in elevation of the return module of the present invention with handles. 
    
    
     DETAILED DESCRIPTION 
     FIGS. 4 a  and  4   b  illustrate one preferred embodiment of the reclose module of the present invention. FIG. 4 a  is a perspective view of the reclose module installed in a prior art sealing carriage, while FIG. 4 b  is a cross-section of the reclose module in position on the bridge assemblies  406 ,  408  without the aligning handle installed, which handle will be described in further detail below. 
     The reclose module is self-contained comprising many of the individual components which together make up the prior art modification embodiment shown in FIGS. 3 a  and  3   b.  With reference to FIG. 4 b,  included within the reclose module are a pair of opposed jaw facings  402 ,  404 , a pair of opposed zipper seal facings  440 ,  442 , heat probes  428 ,  430 ,  444 ,  446 , thermosters  448 ,  450 , heat barriers  436 ,  438 , crumb plates  414 ,  416 , and stripper bars  418 ,  420 . 
     The module itself is mounted onto the sealing carriage at the bridge assemblies  406 ,  408  by four installation bolts  456 ,  460 , two of which are shown in the cross-sectional view of FIG. 4 b.  Two nut wells  464 ,  466  visible on FIG. 4 a  provide access to these bolts  460  and show the relative position of the bolts  460  along the length of a bridge assembly  408 . (FIG. 5 shows the two installation bolts  560 ,  562  that would be received by the nut wells  464 ,  466  shown on FIG. 4 a ). Since installation of the entire module onto the bridge assemblies  406 ,  408  is accomplished by tightening four uniform nuts on four bolts  456 ,  460 , a single socket wrench is the only tool required in changing over from a return module (which will be described below) and the reclose module, and vice versa. 
     The relative vertical positioning of the facings pairs  402 ,  404 ,  440 ,  442  (the jaw facings  402 ,  404  and the zipper seal facings  440 ,  442  are both referred to by Applicants generically as “facings”) have been reversed in the preferred embodiment illustrated. The zipper seal facings  440 ,  442  are now located above the jaw facings  402 ,  404 . This embodiment is preferred because it reduces the need to strip through the thicker zipper seal area on the bag. By reversing the facings  402 ,  404 ,  440 ,  442  relative to their vertical orientation, the zipper seal and the transverse seals can be made first before the bag is filled from what will become the bottom of the bag. With the bag being filled inverted, the area most likely requiring stripping is the transverse seal area, since it is located closest to the product level in a filled bag. Consequently, the stripping gap can be set narrowly in order to efficiently strip this area. The only other adjustment required is that the packaging film must be run upside-down through the form and fill machine. 
     Another distinct advantage of the present invention over the prior art is the added rigidity of the module and the centering of the pressure transmitted to the facings  402 ,  404 ,  440 ,  442  by the force vectors F acting on the bridge assemblies  406 ,  408 . First, all of the various components that make up the reclose module are mounted on or supported by two support members  472 ,  474 . Each support member  472 ,  474  is extremely rigid and made from a contiguous piece of metal or other suitable material such as hardened steel. The front support member  474  (referenced, like all other components referred to by Applicants as “front” or “rear,” from its position on the sealing carriage while viewed by an operator) is constructed to provide a snug fit about the front bridge assembly  408 . The rear support member  472  must have some tolerance in its fit with the rear bridge assembly  406  in order to accommodate the auto-aligning feature of the invention which will be described below. Second, the zipper seal facings  440 ,  442  and jaw facings  402 ,  404  have also been re-oriented so that they are more centrally aligned with the force vectors F acting on the bridge assemblies  406 ,  408 . This alignment with the force vectors F combined with the rigidity provided by the design of the support members  472 ,  474  resolves the pressure loss problem of prior art designs whereby the prior art zipper seal facings tend to deflect away from the package film during sealing. Consequently, the present invention provides for an even distribution of pressure about the zipper facings  440 ,  442 , and the jaw facings  402 ,  404 . This in turn allows the form and fill machine to operate at shorter dwell times and standard temperatures. 
     As noted previously, prior art reclose facing assembly designs do not allow for removal of components from the bridge assemblies, as the alignment of the facing is factory set. Consequently, most repair work that must be done on the prior art facing assembly, such as the replacement of heat probes or thermosters, must take place with the prior art facing assembly installed on the bridge assemblies. This exposes the operator to many of the safety hazards previously discussed. The present invention, however, provides for a self-aligning feature that is accomplished prior to installing the module on the bridge assemblies  406 ,  408 . Consequently, any maintenance that must be performed on the module components can be done safely off-line. This is accomplished by use of an aligning handle as illustrated in FIGS. 5 and 6. 
     FIG. 5 shows one embodiment of the aligning handle  576  installed on a reclose module. FIG. 6 shows the aligning handle  676  without the reclose module attached. The aligning handle  676  is constructed of a rigid material, such as hardened steel, and can be of a contiguous cast design, made up of several major components welded together, or made up of several major components bolted together. Importantly, the aligning handle has two front engaging means  678 ,  680  and two rear engaging means  682 ,  684 . These engaging means  678 ,  680 ,  682 ,  684  in the embodiment illustrated comprise bolts with knobs at one end, but could be of any suitable design to rigidly attach the handle to modules. 
     Returning to FIG. 5, when the aligning handle is placed in the proper position in relation to the accompanying module, each of the four engaging means  578 ,  580 ,  582 ,  584  secure the opposed sections of the reclose module by twisting the respective knobs, which in turn causes the bolts  578 ,  580 ,  582 ,  584  to seat in threaded receivers (indicated by dashed lines  486 ,  488  on FIG. 4 b ) located in the support members  572 ,  574 . These threaded receivers are located such that the zipper seal facings  540 ,  542  and jaw facings  502 ,  504  are aligned once the aligning handle  576  has been properly secured to the reclose module. The entire reclose module can then be carried in one, self-contained package by the aligning handle  576 . 
     To install the reclose module, it is placed in between the bridge assemblies while the sealing carriage is in the open position. The bridge assemblies are then slowly closed such that the installation bolts  560 ,  562  are directed through the respective bolt and nut wells on the receiving bridge assemblies. 
     By referring back to FIG. 4 b,  it can be seen that the front support member  474  is now snugly fitted about the front bridge assembly  408 . Although shown apart in FIG. 4 b,  at this stage the front and rear portions of the module would be held tightly together in an aligned position by the aligning handle. The rear support platform  472  allows for tolerance about the rear bridge assembly  406  in order that this alignment can be maintained while the installation bolts  456 ,  460  are tightened with standard nuts (not shown). Once the nuts have been tightened on the installation bolts  456 ,  460 , the alignment handle is removed and the alignment of the module is thereafter maintained by the installation bolts  456 ,  460 . 
     Returning to FIG. 5, also shown is an electrical quick connect plug  594 . This electrical quick-connect plug  594  consolidates the wiring to various electrical components in the reclose module, such as the heat probes and thermosters. A receiving female outlet for this quick connect plug  594  can be installed on the modified form and fill machine chassis, thereby accommodating a quick and simple positive connection between the electrical control and inputs of the form and fill machine with the electrical components contained within the reclosed module. Although FIG. 5 shows only one quick-connect plug  594 , an alternative embodiment of the reclose module comprises two quick-connect plugs, each with a wire harness directed to electrical components associated with one half of the module. Such a two-plug embodiment would require two separate receiving outlets installed on the chassis of the form and fill machine. Additional electrical controls are added to the form and fill machine to separately control the electrical components associated with the zipper seal facings  540 ,  542 , and would be consolidated in the receiving outlets. 
     Returning to the installation of the invention&#39;s reclose module in a sealing carriage, and comparing FIGS. 3 b  and  4   b,  it can be seen that the channels  341 ,  343 ,  441 ,  443  in the jaw facings  302 ,  304 ,  402 ,  404  that are designed to accommodate the knife are no longer in the same position relative to the bridge assemblies  306 ,  308 ,  406 ,  408 . The knife is not a component of the embodiment of the reclose module shown in FIG. 4 b,  but, rather, remains attached to the bridge assembly  406 ,  408 . Consequently, it is necessary to provide another modification to the sealing carriage in order to account for the lower position of the invention&#39;s jaw facings  402 ,  404 . This is accomplished by knife adapters  801 ,  803  illustrated in FIG.  8 . When using the knife  822  with the reclose module, the knife adapters  801 ,  803  reposition the knife  822  relative to the lower positioned jaw facings  402 ,  404 . 
     The knife adapters  801 ,  803  comprise two extenders  805 ,  807  and two installation pins  809 ,  811 . The installation pins  809 ,  811  hold the knife  822  in the knife adapters  801 ,  803  by positioning the knife  822  in receiving slots  813 ,  815 , and passing the pins  809 ,  811  through a hole  817  in either end of the knife  822 . 
     The knife  422  is installed on the reclose module as illustrated in FIG. 4 a  after the reclose module is installed on the bridge assemblies  406 ,  408 , as described above. The sealing carriage is then opened. The extensions  405 ,  407  are then fitted over the existing knife brackets  424 ,  426 . The knife  422  is inserted into the channel on the rear jaw facing  402 . The installation pins  409 ,  411  are next inserted through holes in the end of each knife bracket  424 ,  426  and holes at the ends of the knife  422 . Likewise, the knife  422  can be removed by reversing the above sequence when the reclose module is removed from the sealing carriage. 
     The installation of the reclose module is completed once the support member installation bolts have been installed on the bridge assemblies, the knife has been properly positioned and attached with the knife adapters, and the electrical quick-connects have been inserted into the receiving outlets on the form and fill machine chassis. The entire installation process takes a single tool, a standard socket wrench, and takes less than fifteen minutes. 
     The reclose module is removed by first opening the sealing carriage. The knife and knife adapters are removed and the electrical quick-connects are disconnected from the chassis. The ceiling carriage is then closed. Next, the aligning handle is attached to the support members as previously described. The nuts are then removed from the support member installation bolts. Finally, the sealing carriage is opened and the reclose module is lifted therefrom by the aligning handle. 
     FIG. 7 shows the rear zipper facing  740  for one embodiment of the present invention. This embodiment shows another novel feature of the invention which eliminates the need for the use of a different zipper seal facing for each different bag width run in the reclose configuration. This is accomplished by using a slotted channel  796  in combination with two inserts  798 ,  799 . The inserts  798 ,  799  slide into and out of the channel, being held in place by the flange configuration of the edges of the channel and/or set screws (not shown). Rather than stocking various sizes of zipper facings having different widths of rectangular relief, different sized inserts  798 ,  799 , used to change the horizontal distance between the two inserts  798 ,  799 , can be kept in stock. Alternatively, a single size set of inserts  798 ,  799  can be used and simply moved horizontally along the channel  796  in order to adjust for the appropriate bag width. The inserts  798 ,  799  themselves can have teeth on their exposed contact surface (as shown), have a flat contact surface, or any other appropriate design. 
     Changing the bag width for a reclose configuration using this feature of the present invention is a relatively simple task. The reclose module is removed from the bridge assembly, as previously described. The operator next removes the reclose module to a work bench or similar area. The aligning handle is removed to allow access to the rear zipper facing  740 . Inserts  798 ,  799  are then removed and replaced with new inserts  798 ,  799  sized for the bag width to be run. Alternatively, the inserts  798 ,  799  are repositioned along the channel in order to adjust the distance separating them for the new bag width required. Removal of the entire zipper facing  740  is not required. The reclose module can then be realigned and reinstalled as previously described. 
     The embodiment of the invention&#39;s reclose module illustrated in FIG. 4 b  shows a rear zipper seal facing  440  with an insert  498  in the slotted channel, while the opposed front zipper seal  442  comprises a flat exposed surface. (This is also evident in FIG. 5.) An alternative embodiment of the invention comprises slotted channels in both the rear zipper facings  440  and the front zipper facings  442 . 
     In order to convert the modified form and fill machine of the present invention back to a standard (no zipper seal facings) configuration, the present invention utilizes what is called a “return” module, which returns the form and fill machine to the standard transverse seal operation. One embodiment of the return module of the present invention is shown in FIG.  9 . The return module shown comprises opposed jaw facings  902 ,  904 , support members  972 ,  974 , heat probes  928 ,  930 , thermosters  932 ,  934 , crumb plates  914 ,  916 , stripper bars  918 ,  920 , and thermal barriers  936 ,  938 . The support members  972 ,  974  are smaller than the support members used in the reclose module, but perform much the same function of maintaining a rigid support base for all of the various components that comprise the return module. 
     The return module is installed on the bridge assemblies  906 ,  908  in a manner similar to that previously described with regard to the reclose module. Specifically, it is attached to the bridge assemblies  906 ,  908  by four bolts  956 ,  960  connected to the support members  972 ,  974 . Since the jaw facings  902 ,  904  are in the same relative vertical positions as in a prior art facing assembly, a knife adapter, such as the one shown in FIG. 8, is not required for the return module. 
     The return module is aligned, stored, and transported using the invention&#39;s aligning handle  676 , as is illustrated in FIG.  6 . FIG. 10 shows the aligning handle  1076  installed on the return module. As with the reclose module, the return module is also equipped with one or more electrical quick disconnect  1094  electrical connections in order to connect the various electrical components of the return module to the modified form and fill machine controls. The installation of the reclose module is completed after the quick disconnect  1094  is mated with a respective plug on the chassis of the form and fill machine and the aligning handle  1076  is removed. The return module then functions just as the prior art facing assembly described in relation to FIG. 1 b.    
     The return module is easily installed in place of the reclose module on the modified form and fill machine of the present invention. Installation or removal of either module takes less than fifteen minutes, can be accomplished with a single standard socket wrench, and minimizes the operator&#39;s exposure to hot components and time spent with digits exposed while the sealing carriage is in the open position. 
     While the invention has been particularly shown and described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the invention.