Abstract:
A device and method of use for applying twist-ties onto flexible packages on an assembly line. Each package has a front panel including an exterior surface. Each twist-tie is a strip of material having a first face. The apparatus comprises a glue applicator (e.g., a spray head), a supply (e.g., reel) of twist-tie material, a carrier (e.g., channel shaped head including magnets), and a package support (e.g., conveyor). The package support holds each package at a first station in an orientation whereupon the exterior surface of the front panel is oriented vertically. The carrier is arranged to be oriented in a first horizontal position for receipt of a respective twist-tie thereon so that the first face of the twist-tie is facing upward. The glue applicator applies glue (e.g., sprays hot glue) downward onto the first face of the twist-tie as it is advanced onto the carrier. The carrier is pivotable to a position so that the glued first face of the twist-tie is oriented in a vertical plane facing the exterior surface of the front panel of the package and is then movable in a horizontal direction to carry the twist-tie into engagement with the exterior surface of the front panel of the package to fixedly secure the twist-tie thereon. The carrier includes an air jet to aid in the release of the twist-tie from the magnetic holding of the carrier. The carrier is then brought back to its original position for receipt of another glue-bearing twist-tie thereon.

Description:
RELATED APPLICATIONS 
     This application is a Divisional of our earlier filed U.S. patent application Ser. No. 09/734,121, filed on Dec. 11, 2000 now U.S. Pat. No. 6,453,967, entitled Compound Motion Apparatus and Method for Applying Twist-Ties to Flexible Packages, whose disclosure is incorporated by reference herein, and which is assigned to the same assignee as the subject invention. 
    
    
     BACKGROUND OF THE INVENTION 
     This invention relates generally to apparatus for making flexible packages, and more particularly to apparatus for applying twist-ties to reclosable, flexible packages. 
     Various types of flexible packages for holding particulate materials, e.g., ground or whole bean coffee, cereals, cookies, etc., have been disclosed in the patent literature and are commercially available today. “Twist-ties” (sometimes also referred to as “tin-ties”) are frequently incorporated into such packages to enable the packages to be reclosed for multiple serving usage. In particular, such twist-ties are elongated strips commonly made of either plastic and wire or paper and wire, with the wire being embedded in the plastic or paper. The twist-tie is fixedly secured on one of the panels of the package adjacent the package&#39;s mouth. After the mouth of the package has been opened and some of the package&#39;s contents removed, the package can be reclosed by folding or rolling the upper end (the mouth) of the package about the twist-tie, with the ends of the twist-tie extending beyond the margins of the rolled/folded portion. The ends of the twist-tie can then be bent or folded over the rolled/folded mouth to prevent it from unrolling/unfolding, thereby keeping the mouth closed to prevent air from reaching the remaining contents in the package. 
     Heretofore the application and securement of a twist-ties to poly-laminate or other material flexible packages on an assembly line has been accomplished in several ways. For example, in one way an applicator is used to apply, e.g., spray, hot glue to one face of a strip of twist-tie material while the strip is held in vertical plane on a wheel or disk arranged to be rotated about a horizontal axis. Once the glue has been applied to the twist-tie the disk is rotated 90 degrees to carry the twist-tie with its adhesive-bearing face directed toward a horizontally oriented flexible package (e.g., bag) onto which it is to be secured. The bag is then pressed against the glue-bearing twist-tie. This method of applying twist-tie to a flexible package is shown in U.S. Pat. No. 5,389,190 (Larsen et al.). 
     A second way of applying a twist-tie to flexible packages on an assembly line is to apply, e.g., spray, the hot glue directly to a preselected area on each bag while the bag is held in a vertical plane. Then the twist-tie can be pressed onto the bag in the area bounded by the applied glue. 
     Both of such methods of application suffer from one or more drawbacks. For example, the disadvantage of applying glue to the twist-tie on a disk and then rotating the disk, as described above, is that the glue is applied from a horizontal direction onto a vertically oriented twist-tie strip. Accordingly, the force of gravity tends to pull the hot glue downward and away from (off) the twist-tie strip as the strip is carried into a horizontal orientation for application to a horizontally oriented bag. If there are inconsistencies in the glue material, the application of the glue to the twist-tie becomes unreliable, resulting in misapplication of the twist-tie to the package. 
     The disadvantages of applying glue directly to the bag while the bag is held in a vertical orientation and then pressing the twist-tie against the glue-bearing area on the bag is three-fold. First, since the glue is applied from a horizontal direction onto a vertically oriented bag, the force of gravity will also act to pull the glue downward and away from (off) the area of the bag to receive the twist-tie strip. If there are inconsistencies in the glue material, the application of the glue to the twist-tie bearing portion of the bag becomes unreliable, resulting in misapplication of the twist-tie to the bag, as well as “stringing” of residual glue between the glue applicator head and the bag, thereby resulting in an off-quality bag (i.e., a bag with glue extending out beyond the margins of the twist-tie). The second disadvantage of this method of twist-tie application is that since the bag is formed of a flexible material, e.g., a polylaminate, if the bag flexes between the glue application and the twist-tie application, the twist-tie may not be placed onto the glue strip. The third disadvantage is that if the bag is missing on the conveyor or other device for carrying the bags to the glue head and the glue head is activated, then the hot glue can be dispensed into the machine, resulting in reliability and safety issues. 
     Examples of other apparatus for applying twist-ties to packages are found in the following U.S. Pat. Nos. 3,534,520 (Moran), 3,825,039 (Crabb), 3,890,190 (Eburn, Jr. et al.), 3,895,989 (Lucas), 3,919,8290 (Burford et al.), 4,420,355 (Saur), 4,490,960 (Klemestrud), 4,559,766 (Matsushita), 4,559,977 (Dilley), 4,586,412 (Johnson), 4,655,264 (Dilley), 4,660,351 (Saitoh), 4,696,244 (Sampson et al.), 4,730,434 (Knudsen), 5,045,042 (Rutledge), 5,121,682 (Parker et al.) and 5,402,619 (Nelson et al.). 
     SUMMARY OF THE INVENTION 
     These and other objects of the instant invention are achieved by providing apparatus and a method for applying twist-ties to a flexible packages. Each package comprises a front panel including an exterior surface. Each of the twist-ties comprises a strip of material having a first and a second opposed faces. 
     The apparatus basically comprises a glue applicator, a supply of twist-tie material, a carrier, and a package support. The package support is arranged to hold the package at a first station in an orientation, whereupon the front panel of the package is oriented in a vertical plane. The carrier has a twist-tie receiving face and is arranged to be oriented in a first position, wherein its twist-tie receiving face is in a horizontal plane. The supply of twist-tie material is arranged to sequentially provide respective twist-ties to the twist-tie receiving face of the carrier so that the first face of each respective twist-tie is facing upward. The glue applicator is disposed above the carrier and arranged for applying glue downward onto the upwardly facing first face of each respective twist-tie. 
     The carrier is pivotable to a second position after the glue is applied to the first face of the twist-tie, wherein the first face of the twist-tie is oriented in a vertical plane facing the exterior surface of the front panel of the package on the package support at the first station. The carrier is also movable in a horizontal direction to carry the twist-tie with the glue on its first face into engagement with the exterior surface of the front panel of the package to fixedly secure the twist-tie thereon. 
    
    
     DESCRIPTION OF THE DRAWING 
     FIG. 1 is an isometric view of a portion of one exemplary twist-tie applying apparatus constructed in accordance with this invention for adhesively securing twist-ties onto flexible packages, e.g., bags, on an assembly line basis; 
     FIG. 2A is an isometric view of the portion of the apparatus of FIG. 1 showing the apparatus after a twist-tie has had glue applied to its exposed (upwardly directed) surface and has been delivered to a carrier of the apparatus for application to a bag; 
     FIG. 2B is a side elevational view of the portion of the apparatus shown in FIG. 2A, but with a portion of the apparatus removed for clarity; 
     FIG. 3A is an isometric view of the portion of the apparatus of FIG. 1 showing the apparatus after the twist-tie with the glue applied to its exposed surface has been pivoted to a position opposite the bag onto which it is to be adhesively secured; 
     FIG. 3B is a side elevational view of the portion of the apparatus shown in FIG. 3A, but with a portion of the apparatus removed for clarity; 
     FIG. 4A is an isometric view of the portion of the apparatus of FIG. 1 showing the apparatus after the carrier bearing the glue-bearing twist-tie has been extended into the position wherein the glued surface of the twist-tie is in intimate engagement with a portion of the bag to adhesively secure the twist-tie to the bag; 
     FIG. 4B is a side elevational view of the portion of the apparatus shown in FIG. 4A, but with a portion of the apparatus removed for clarity; 
     FIG. 5A is an isometric view of the portion of the apparatus of FIG. 1 showing the apparatus after the carrier has been retracted, leaving the twist-tie adhesively secured to the bag; 
     FIG. 5B is a side elevational view of the portion of the apparatus shown in FIG. 5A, but with a portion of the apparatus removed for clarity; 
     FIG. 6A is an isometric view of the portion of the apparatus of FIG. 1 showing the apparatus after the carrier has been pivoted back to its home position ready for receipt of another twist-tie thereon; and 
     FIG. 6B is a side elevational view of the portion of the apparatus shown in FIG. 6A, but with a portion of the apparatus removed for clarity. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to FIG. 1, there is shown at  20  in FIG. 1 one exemplary embodiment of an apparatus constructed in accordance with this invention for applying twist-ties  10  onto flexible packages  12 . Before discussing the apparatus  20 , a brief discussion of the construction of the twist-tie  10  is in order. To that end each twist-tie is of conventional construction, e.g., it comprises a ribbon-like web of material, such as plastic or paper, having a pair of wires or other deformable members extending along the web&#39;s respective marginal edges and embedded in the plastic or paper material. Being a ribbon-like web, the twist-tie includes an opposed pair of faces  10 A and  10 B (FIG.  5 B). In accordance with a preferred embodiment of this invention the wires making up the twist-tie are steel or some other material that is attracted to a magnet to expedite the holding of the twist-tie in place on a magnetic carrier head (to be described later) forming a portion of the apparatus  20 . 
     As can be seen in FIG. 1, the apparatus  20  basically comprises a conveyor  22  for carrying a plurality of flexible packages, e.g., bags,  12  one-by-one in the direction of the arrow shown in that figure to an applicator unit or assembly  24  at which a respective twist-tie  10  is applied to the package. The applicator assembly will be described in detail later. Suffice it for now to state that it includes the heretofore identified magnetic carrier head. Associated with the applicator assembly  24  is a twist-tie supply assembly  26 . The twist-tie supply assembly  26  basically comprises a reel  28  of ribbon-like material  14  for making respective twist-ties therefrom and plural rollers  30  for carrying the ribbon-like material  14  to a knife assembly  32  where it is cut into respective predetermined lengths to form respective twist-ties  10 . In particular, the ribbon-like material  14  is pulled from the reel  28 , deposited on the magnetic carrier head of the applicator assembly  24  by a pair of drive rollers  34 . The drive rollers  34  are located adjacent the upstream side of the applicator assembly  24  to pull the leading portion of the web of material  14  in a horizontal plane, with a face of the ribbon-like material facing upward onto the magnetic carrier head. The knife assembly  32  is located downstream of the drive rollers  34  and immediately upstream of the magnetic carrier head of the applicator assembly  24  to sever the leading end of the ribbon-like material  14  deposited on the carrier head at a predetermined point from the free end thereof to complete the formation of the twist-tie  10  on the carrier head. The length of the twist-tie, i.e., the distance between its free ends, is preferably greater than the width of the bag onto which it is to be applied, as is conventional. In the embodiment shown each bag  12  includes a front panel  12 A, a rear panel  12 B, a pair of gusseted side panels  12 C and a flanged, sealed top  12 D. 
     A glue applicator  36 , e.g., a hot-melt glue spray head, is located downstream of the knife assembly  36  and above the upstream end of the carrier head to spray a single stream of hot melt glue onto the upwardly directed face of the ribbon-like material  14  as it is fed onto the carrier head. The glue spray head  36 , along with the other components of the apparatus, such as the knife assembly, the conveyor, etc., is controlled by an electrical controller (not shown) so that the spray head starts depositing of the glue on upper face of the material  14  at a predetermined distance from the leading end of the material  14  (i.e., what will be the leading end of the twist-tie  10  to be made) and stops depositing the glue a predetermined distance from the point at which the material  14  is severed by the knife assembly  32  (i.e., what will be the trailing end of the twist-tie  10 ). In particular, the apparatus is arranged so that the glue is applied to the central portion of the twist-tie for a length equal to approximately the width of the front panel, i.e., the distance between the two opposed gusseted side panels  12 C. The upper face of the material  14  to which the glue is applied becomes the face  10 A of the twist-tie  10  and is the face that becomes adhesively secured to the exterior surface of the top flange portion  12 D of the front panel  12 A of the package  12 . When secured, as will be described later, the twist-tie is centered on the package so that its free ends extend a short distance beyond the marginal edges of the flanged top  12 D, as is conventional. 
     Referring now to FIGS. 2A and 2B it can be seen that the applicator assembly  24  includes a solenoid controlled, dual-rod, pneumatic cylinder  38 . The cylinder includes a pair of rods  40  coupled to the piston (not shown) in the pneumatic cylinder. Each rod  40  has a free end on which a block  42  is mounted. The dual-rod cylinder  38  is itself mounted on a support plate, which also supports two blocks  46  to which a pair of linear bearings  44  are mounted. A pair of guide rods  48  extend into respective ones of the linear bearings  46 . A coil spring  50  is interposed between one linear bearing  46  and a stop washer  52  on one of the guide rods and a similar coil spring is interposed between the other linear bearing and a stop washer on the other guide rod. The coil springs are compression springs which are loaded slightly to bias the carrier head in the normal or retracted “home” position shown in FIGS. 2A and 2B so that the carrier head is away from the flange of the bag on which the twist-tie is to be adhesively secured. 
     A rack gear  54  is fixedly mounted on a lower portion of the block  42  and projects horizontally therefrom. The rack gear has plural teeth extending upward along its top edge which intermesh with plural teeth disposed around the periphery of an idler gear  56 . The idler gear is mounted on a main housing  58 . The main housing  58  serves to pivotably mount the magnetic carrier thereon, as will be described later. The idler gear  56  is mounted on a shaft that extends through a bearing (not shown) within the main housing  58 . Also mounted on the main housing  58  is a sector gear  60 . The sector gear is mounted on a shaft (not shown) extending through a pivotable support member  62 . The idler gear&#39;s teeth engage the teeth of the sector gear  60 . 
     The heretofore mentioned magnetic carrier head, now designated by the reference number  64 , is mounted on the pivotable support member  62 . The carrier head  64  basically comprises a an elongated channel-shaped member having a slot or channel  66  extending along its upper surface between a pair of upwardly directed marginal flanges. When the dual rod cylinder is in its retracted (home) position, the bottom of the channel  66  of the carrier head is in a horizontal plane, slightly lower in elevation than the plane of the incoming ribbon-like material for forming the twist-tie. 
     The leading edge of the carrier head&#39;s channel  66  is chamfered (See FIGS. 5A and 6A) to facilitate the introduction of the free end of the ribbon-like material  14  therein during the formation of the twist-tie as described above. Plural magnets (not shown) are located within the carrier head below the channel  66 . The magnets serve to magnetically attract the wires of the twist-tie to hold the twist-tie in place within the channel  66 . 
     The channel-shaped carrier head  64  is mounted on the support member  62  so that when the carrier head is in its normal, retracted or “home” position, as shown in FIG. 2A, the channel  66  faces upward. Accordingly, the surface  10 A of the twist-tie bearing the glue applied by the glue spray head  36  also faces upward and is disposed horizontally. The glue spray head is mounted so that its single stream or jet of glue is directed from its nozzle onto the upper surface  10 A of the twist-tie, but not onto the carrier&#39;s flanges on either side of the channel  66 . 
     As can be seen in FIGS. 1,  2 A and  2 B, the apparatus  20  also includes an anvil  68  located immediately to the side of the conveyor  22  opposite to the carrier head. The anvil is an elongated member having a planar front face and is mounted on a support (not shown) so that its front face is at the height at which the magnetic carrier member holding the glue-bearing twist-tie is extended into contact with the exterior surface of the top flange  12 D of the package  12 . 
     Once the twist-tie  10  has had glue applied to its upper face  10 A and is residing in the channel  66  of the carrier head  64 , with the carrier&#39;s channel disposed in a horizontal plane facing upward, like that shown in FIG. 2A, the apparatus is ready to be pivoted to orient the twist-tie into a vertical position for application onto the exterior surface of the front face of the flanged top of the bag. To that end, as can be seen in FIG. 3B, the piston in the pneumatic cylinder is operated to cause the two rods  40  to extend outward (to the right in FIGS. 3A and 3B) carrying the block  42  with them. Since the rack gear  54  is mounted on the block  42 , the rack gear also moves outward (to the right). The loading on the coil springs  50  surrounding the guide rods  48  prevents the guide rods from moving into their respective linear bearings  46 , while also preventing the main housing  58  from moving with the rack gear  54 . The outward movement of the rack gear  54  causes the counterclockwise rotation of the idler gear  56 , which in turn causes the clockwise rotation of the sector gear  60 . This action pivots the carrier support member  62  and the magnetic carrier head  64  mounted thereon ninety degrees from its normal or home position (shown in FIGS. 2A and 2B) to the vertical orientation shown in FIGS. 3A and 3B. 
     Because the main housing is mounted on the spring loaded guide rods and pressure is applied by the springs in the opposite direction of the motion of the cylinder&#39;s rods  40 , the first portion of the extension of the block  42  does not push the main housing  58  closer to the bag  10 . Instead, this first 30%-50% of the cylinder&#39;s stroke translates the rack gear relative to the idler gear. As described above this results in a rotary motion of the carrier head, 90° of rotation, (clockwise as seen from the right side of the applier) until the mechanism reaches its mechanical stop, i.e., the block  42  contacts the main housing  58 . 
     Since the twist-tie is held magnetically within the channel  66  by the magnets of the carrier head, the pivoting of the carrier head to the vertical orientation will not result in the twist-tie falling out or otherwise being displaced during that movement. The carrier head is prevented from pivoting beyond 90° by virtue of the fact that the block  42  engages the main housing  58  when the head is at the vertical orientation shown in FIGS. 3A and 3B. At this point, the carrier head with the twist-tie magnetically held within the channel is located opposite the anvil  68  with the flange  12 D of the package  12  interposed therebetween and with the adhesive surface  10 A of the twist-tie  10  facing the exterior surface of the front panel portion of the flange  12 D. 
     Continued operation of the pneumatic cylinder carries the rods  40  with the block  42  mounted thereon further outward, but the result of this final 50%-70% of the cylinder&#39;s stroke is the linear extension of the main housing and the carrier head mounted thereon. In particular, the continued operation of the cylinder causes the two guide rods  48  to begin moving through their respective linear bearings  46  since the block  42  cannot move any further due to its contact with the main housing  58 . Accordingly, the two coil springs  50  begin to compress between their respective linear bearings  46  and their stop washers  52  on the guide rods  48 . This action moves both the block  42  and the main housing  48  toward the exterior surface of the package&#39;s flange  12 D as shown in FIGS. 4A and 4B, thereby carrying the adhesive-bearing twist-tie in the carrier head  64  into contact with that portion of the exterior surface of the top flange of the package. The assembly  24  is arranged so that at the maximum extent of the extension of the carrier head  64 , the adhesive surface  10 A of the twist-tie  10  intimately engages the exterior surface of the flange  12 D, with the anvil&#39;s front face serving as a backstop. Accordingly, the twist-tie is effectively adhesively secured to the exterior surface of the bag&#39;s top flange at the front panel, with the marginal ends of the twist-tie extending beyond those marginal edges. Once the twist-tie is brought into engagement with the bag  12 , as just described, the apparatus  20  is arranged to be retracted under the automatic control of the controller. In particular, after a predetermined apply time, a solenoid valve (not shown) for the dual rod cylinder  38  is de-energized, and the cylinder&#39;s piston begins to retract. Because the springs  50  are under compression, the main housing  58  and the carrier head  64  mounted thereon retracts along with the cylinder&#39;s piston. This operation is shown in FIGS. 5A and 5B and will be described hereinafter. However, before doing that, it should be noted that in order to ensure that the twist-tie is released from its magnetic engagement within the carrier head&#39;s channel  66  when the carrier head is to be retracted, the carrier head  64  includes a plurality of air jet ports  70  (FIGS. 1,  2 B,  3 B,  4 B and  5 B) located therein. The air jet ports  70  are in communication with a source of compressed air (not shown) which is operated automatically by the controller (not shown) to produce an air blast to facilitate ejection of the twist-tie from the carrier head. The air blast remains energized from the time the twist-tie is pressed onto the bag until well after the carrier head has begun retracting. 
     The retraction of the carrier head is accomplished by providing air into the pneumatic cylinder  38  in an opposite direction from that provided to extend the carrier head toward the bag, to cause the cylinder&#39;s internal piston to move the rods guide rods  48  in the opposite direction from that described heretofore, i.e., right to left as shown in FIGS. 5A and 5B. This opposite air pressure, along with the bias provided by the compressed springs  50 , carries the main housing  58  and the guide member support  64  with it back towards its retracted position, whereupon the springs  50  return to their natural position as shown in FIGS. 5A and 5B. This action leaves the twist-tie  10  adhesively secured on the exterior surface of the bag&#39;s flange  12 D, with the opposed ends of the twist-tie extending beyond the marginal edges of the flange as best seen in FIG.  5 A. 
     Continued retraction of the piston in the pneumatic cylinder  38  carries the block  42  away from the main housing  48 , whereupon the rack gear  54  is carried away from the main housing  58 . This action causes the idler gear  56  to rotate clockwise, which in turn causes the sector gear  60  to rotate counterclockwise, thereby bringing the carrier head back to its home position, i.e., horizontal orientation, under the glue spray head  36  as shown clearly in FIGS. 6A and 6B. 
     The conveyor  22  is then operated by the controller to carry the package  12  with the twist-tie  10  adhesively secured to it from station at which the twist-tie applicator assembly  24  is located and to bring the next successive package to that station so that its flange is located adjacent the anvil and the carrier head for application of a twist-tie to that package. 
     As should be appreciated from the foregoing the apparatus and method of this invention offer various advantages over the prior art. In particular, the application of glue directly downward from a glue applying, e.g., spray, head onto a horizontally disposed twist-tie has the advantage that inconsistencies in the glue material have little or no effect on the glue application since gravity actually helps to pull the glue onto the twist-tie. Moreover, since the glue is applied directly to the twist-tie, alignment between the twist-tie and glue stripe is ensured. 
     As should be appreciated by those skilled in the art, the various components making up the system  20  are merely exemplary of numerous components that could be used in the system, e.g., a hydraulic cylinder or an electrically operated linear motor could be used to move the carrier head. The carrier head need not include magnets or have airfits, etc. 
     Without further elaboration the foregoing will so fully illustrate our invention that others may, by applying current or future knowledge, adopt the same for use under various conditions of service.