US2978852A - Bag top closing and sealing machine - Google Patents

Description

April 11, 1961 F. L. HOPKINS ETAL 2,978,852?

BAG TOP CLOSING AND SEALING MACHINE Filed March '7, 1960 5 Sheets-Sheet 1 8Q JNVENTORS FRANKLHOPK/NS y RICHARD h. A YRES 7 ATTORNEYS April 11, 1961 F. L. HOPKINS ET AL 2,978,852

BAG TOP CLOSING AND SEALING MACHINE 5 Sheets-Sheet 2 Filed March '7, 1960 April 1951 F. L. HOPKINS ETAL 2,978,852

BAG TOP CLOSING AND SEALING MACHINE Filed March 7, 1960 5 Sheets-Sheet 3 FIG. 4

INVENTORS FRA NK 1.. HOPKINS 1 By RICHARD h. AYREJ (47TORNEYJ TRA VEL April 11, 1961 F. HOPKINS ETAL 2,978,852

BAG TOP CLOSING AND SEALING MACHINE Filed March 7, 1960 5 Sheets-Sheet 4 -I l 4 4 85 I I] 4 l! 1 -93 I] I 92 u l INVENTORS FRANK L HOPKINS y RICHARD /1./4 YRES A 7- TORNE Y6" April 11, 1961 F. HOPKINS ETAL 2,978,352

BAG TOP CLOSING AND SEALING MACHINE 5 Sheets-Sheet 5 Filed March 7, 1960 il I r -g:fl-9,

FIG. 11

5 5m H mm N m t m T L mw NH mm W R WW FIG. 9

United States Frank L. Hopkins and Richard H. Ayres, Minneapolis,

Minn, assignors to Bemis Bro. Bag Company, Minneapolls, Mlnn., a corporation of Missouri Filed Mar. 7, 1960, Ser. No. 13,376

12 Claims. (Cl. 53-137) This invention relates, to newand useful improvements in machines for closing and sealing the open tops of relatively large flexible walled bags by firmly pressing the walls of each bag top into flatwise relation and sewing them together by a row of stitches extending the length of the bag top and folding a strip of sealing tape over the closed bag top walls and adhering it thereto by coacting pressure means, as disclosed in Patent No. 2,845,- 760, granted August 5, 1958.

The present invention distinguishes from the machine disclosed in the above noted patent in that independent means is provided for pressing the walls of the sealtape into firm contact with the bag top walls closely adjacent to the opposed sides of the row of stitching, thereby to prevent any possible danger of leakage in the composite bag top closure along the row of stitching, as is possible with sewn bag tops as now commonly constructed.

According to the present invention a thin flexible thermo-plastic coated sealing tape is folded over the sewn bag top walls with the side walls overlying and concealing the row of stitches thereof in such a manner that when the operation of closing and sealing the bag top has been completed, it is unlikely that the sealed bag top will become defective or leaky from rough handling and treatment in transit.

Applicants have discovered that to assure the formation of a positive leakproof closure of the type wherein the bag top walls are secured together by a row of chain stitching, and a strip of adhesive coated sealing tape is then folded over the flattened bag top walls and secured thereto by passing the tape-covered bag top between a pair of co-acting pressure elements, that leakage may occur along the row of stitching because of the inability of the pressure elements to press the walls of the sealing tape into intimate bonding engagement with the bag top Walls in close proximity to the chain stitching.

After considerable experimental work in an effort to provide a hermetically sealed bag top closure, applicants discovered that by utilizing a thin flexible thermo-plastic coated sealing tape and pressing the walls of the sealing tape into bonding engagement with the flattened bag top 'walls by co-acting pairs of dual belt runs, the belt runs of each pair of dual belt runs being vertically spaced apart to straddle or receive the row of chain stitching therebetween, that the belts of each dual belt run can be so arranged that they will engage the tape walls in close proximity to the opposed sides (top and bottom) of the chain stitching, whereby the needle holes are positively sealed against leakage and thus assuring a hermetically sealed bag top closure.

An important object of the present invention, therefore, is to provide independent pressure means for engaging each wall of the sealing tape above and below the row of chain stitching of the bag top, which pressure means is heated to thereby reactivate the plastic coating on the inner surfaces of the tape walls whereby the atent O:

. Patented Apr. 11, 1961 2 tape walls may be firmly bonded to the bag top walls adjacent to each side of the row of chain stitching.

A further object of the invention is to provide a mechanism for positively sealing closed bag tops after the walls of the bag tops have been secured together by a row of chain stitching, said mechanism including means for applying a strip of thermo-plastic coated sealing tape over the flattened bag top walls and folding the side wall portions of the tape downwardly into engagement with the flattened bag top walls and overlying and concealing the row of chain stitching, and vertically spaced means being provided at each side of the flattened.

bag top walls for straddling the row of chain stitching and firmly pressing the tape walls above and below the row of chain stitching into firm and intimate bonding engagement with the bag top walls closely adjacent to the chain stitching, thereby positively sealing the needle holes against leakage and assuring a hermetically sealed closure;

A further and more specific object of the invention resides in the provision of pairs of dual belt runs engageable with the tape walls at opposite sides of the bag top, and the belt runs of each pair of dual belt runs being spaced apart vertically to provide a gap therebetween for receiving the row of stitching, and whereby the tape walls are pressed into firm contact with the walls of the bag top adjacent to each side of the chain stitching.

A further object resides in the provision of means for heating the dual pairs of belt runs whereby the thermoplastic coating on the inner surfaces of the tape walls may be reactivated to assure an intimate bond between the tape walls and the bag top walls.

Other objects of the invention reside in the specific construction of the tape heating means which comprises one or more fixed heating bars located at one side of the travel path of the bag tops, and a plurality of floatingly mounted heating bars at the opposite side of said travel path, said floatingly mounted heating bars having means for yieldably retaining them in engagement with the dual pairs of belt runs, thereby to heat the belt runs and at the same time firmly holding them against the tape walls as the bag tops travel through the apparatus; the floatingly mounted heating bars also allowing the metal belt runs to closely follow the contour of the bag tops, when sealing the tops of gusseted bags which are not of uniform thickness because of the intucked end walls; and in the provision of means for automatically maintaining said heating bars at a predetermined temperature.

Other objects of the invention reside in the means provided for driving the pairs of dual belts in synchronism with the movement of the bag bodies through the machine; and in the prow'sion of a bag top sealing mechanism which is extremely simple and inexpensive to manufacture.

These and other objects of the invention and the means for their attainment will be more apparent from the following description taken in connection with the accompanying drawings.

In the accompanying drawings there has been disclosed a structure designed to carry out the various objects of the invention, but it is to be understood that the invention is not confined to the exact features shown, as various changes may be made within the scope of the claims which follow.

In the drawings:

Figure 1 is a front elevation of the machine showing the bag tops as they are successively fed. through the machine;

Figure (2 is a sectional plan view substantially on the line 2-2 of Figure 1, with some of the parts omitted, showing the travel path of the bag tops, and the arrangement of the heating bars along the sides thereof, some of the parts being broken away;

Figure 3 is a diagrammatic view showing the drive means for the dual endless steel belts and the compression rolls; 1

Figure 4 is a sectional plan view on the line 4-4 of Figure 6, on an enlarged scale, showing the stationary and theresiliently mounted heating bars, and the conductor bars for conducting heat from the heating bars to the co-acting belt runs which directly engage the tape walls, and partially showing the means for tensioning the dual metal belts;

Figure 5 is a cross-sectional view on the line 55 of Figure 4, showing the vertical spacing between the dual belts of each pair of dual belt runs, thereby to accommodate the row of chain stitching therebetween, and whereby the walls of the sealing tape are pressed firmly into intimate bonding engagement with the flattened bag top walls in close proximity to the chain stitching, and also showing the means for tensioning the dual metal belts;

Figure 6 is a cross-sectional elevation on the line 6-6 of Figure 4, showing the independent mounting of the belt-supporting pulleys at the receiving end of the apparatus;

Figure 7 is a fragmentary view, partially broken away,

showing the means for anchoring the resiliently mounted heating bars against longitudinal movement;

Figure 8 is a fragmentary view on the line 8-8 of Figure 7, on an enlarged scale;

Figure 9 is a view showing the upper portion of a sealed bag top having a sealing tape or membrane applied thereto in accordance with the present invention;

Figure 10 is a detail sectional view on the line 1tl-1 of Figure 9, indicating in dotted lines, how the walls of the sealing tape are pressed into firm bonding engagement with the bag top walls above and below the row of chain stitching by the pressure exerted on the tape walls by the co-acting heated belt runs; and

Figure 11 is a fragmentary view, partially broken away, showing the pressure rolls at the discharge end of the apparatus for firmly pressing the tape walls into intimate contact with the bag top walls and the chain stitching, as each bag top is discharged from the machine.

Main supporting frame The novel bag top closing and sealing mechanism herein disclosed comprises an elongated main supporting frame 2, shown having a mounting plate 3 at one end to facilitate attaching it to a bag top sewing mechanism, not shown .in the drawings, such as shown in Figures 1 and 3 of Patent No. 2,845,760. The frame comprises a horizontal wall portion 4 and a rear upright wall portion 5 which cooperate to form an angular frame section, as best illustrated in Figure 5.

The'main supporting frame also comprises an elongated front angular frame section 6 secured to the rear frame section 2 by laterally disposed frame sections 7 and 8 at the front and rear ends ofthe frame, respectively, and intermediate cross members 9 and 11, best illustrated in Figure 2. The bag top closing and sealing mechanism herein disclosed distinguishes from the machine disclosed in theabove mentioned patent in the means provided for pressing the tape walls into bonding engagement with the flattened bag top walls.

Tape applying mechanism Heretofore, co-acting single belt runs have been utilized for pressing the walls of a sealing tape into engagement with the bag top walls. This method of pressing the sealing tape into engagement with the bag top walls has not proven entirely satisfactory because when utilizing only'a single belt run at each side of the bag top, the needle holes of the chain stitching are not completely sealed adjacent to the row of stitching because of the inability of such belt runs (usually rubber) pressing the tape walls into firm bonding engagement with the bag top walls in close proximity to the opposed sides of the chain stitching with suflicient pressure to assure a leaktight connection between the tape walls and the bag top walls along these areas. In such known equipment the actual sealing of the tape walls to the walls of the bag top is accomplished by a pair of rubber-faced pressure rolls between which each bag top must pass as it leaves the rubber belts.

To thus press the walls of the sealing tape into engagement with the bag top walls closely adjacent to the opposite sides of the chain stitching, dual belts l2 and 13 are provided at each side of the travel path of the bag tops, as best illustrated in Figures 1, 8 and 10. These belts are preferably constructed of flexible band metal and are supported at the receiving end of the machine upon independently mounted pulleys 14 and 15. These pulleys are independently adjustable to maintain the endless belts 12 and 1.3 at the proper operating tension, as will subsequently be described.

Belt supporting and drive means At the discharge end of the machine the endless belts 12 and 13 are supported upon drive pulleys 16, secured to the lower ends of upright shafts 17 and 17 mounted in suitable upright bearings 18 forming a part of the main supporting frame. Secured to the upper ends of shafts 17 and 17 are a pair of spur gears 19 and 19, respectively, which mesh with one another to cause the shafts 17 and 17' to rotate in opposite directions, as indi cated by the arrows in Figure 3. A sprocket wheel 21 is secured to shaft 17 directly above spur gear 19, and has a driving connection with a drive chain 2 2, the opposite end of which is connected to a source of power, subsequently to be described.

A second sprocket wheel 23 is secured to shaft 17 above sprocket wheel 21, and has a chain 24 connecting it to a sprocket wheel 25 secured to the upper end of a shaft 26, mounted in a bearing 27 of the main frame. A pressure roll 28 is secured to the lower end of shaft 26 and cooperates with a similar roll 29 to impart a final squeezing action to each bag top as it is discharged from the machine. Annular resilient inserts 31 are seated in annular grooves provided in the peripheries of pressure rolls 2% and 2h, and are located at an elevation to engage and press the sealing tape into intimate bondingengagement with the chain stitching, as is best illustrated in Figure 11.

Roller 29 is secured to the lower end of a shaft 32 rotatably mounted in a bearing member 33 having laterally extending arms 34 and 35 bored to receive the end portions of a stub shaft 36, secured in a hub 37 of the machine frame. A set screw 38 secures the stub shaft 36 against axial and rotary movementsin the hub 37. The upper ends of shafts 26 and 32 are operatively connected together by a pair of spur gears 39 and 41, respectively, as indicated in-Figures l and 3, whereby the pressure rolls 28 and 29 are rotated in opposite directions, as indicated by the arrows in Figure 3.

Pressure rolls 28 and 29 are yieldably held in engagement with the flattened tape-covering bag top, as shown in Figures 2 and 11, by a tension rod 42 having one end secured in a lug 43 provided on the bearing member 27 of shaft 26, as clearly illustrated in Figure 2. The opposite end portion of rod 42 is slidably received in a lug 44 secured to hearing member =33 of shaft 32, and has a spring 45 coiled about one end portion thereof, one end of which is seated against lug 44, and its opposite end against a washer-and-nut combination 46, whereby the spring may be tensioned to constantly urge roller 2 in a direction towards roller 23. The pressure exerted upon the bag top by rollers 28 and 29 may be varied as desired by manipulation of nut 46.

The means for driving the dual belts 12 and 13 and the pressure rolls 2% and 29 is best illustrated in Figure l, and comprises a speed reducer 47 having a shaft 48 to which is secured a V-pulley 49 having a V-belt 51 connecting it to a suitable source of power such as an electric motor, not shown in the drawings. The speed reducer has a depending speed reduction shaft 52 to the lower end of which a sprocket wheel 53 is secured. Sprocket 53 has a driving connection with chain 22, as will be noted by reference to Figure l. A chain tightener, generally indi cated at 54, is adjustably mounted on a bracket 55 secured to the upright wall portion 5 of the main supporting frame, as indicated at 56 in Figure 1. Sprocket 54 provides means for maintaining chain 22 at the proper operating tension.

Mounted on shaft 52 directly above sprocket 53 is a similar sprocket '57 having a chain 58 connecting it to a sprocket wheel 59 secured to the upper end of a shaft 61. Secured to the lower end of shaft 61 is a bag top feed roll 62 which cooperates with a similar roll 63, indicated in Figure 2, to successively feed the bag tops from the tape folder 64, partially indicated in Figures 1 and 2, to the dual belt runs 12 and 13, as will be understood by reference to Figures 1 and 2.

Suitable means, not shown, is provided for supporting a roll of tape over the machine and guiding it into the tape folder 64-. Such a mechanism is shown and described in Patent No. 2,845,760, and it is therefore believed unnecessary to herein describe said mechanism in detail. The bag top feed rolls 62 and 63 are interconnected by a pair of spur gears 65, indicated in Figure 1. A tape clipper, generally indicated by the numeral 50, is shown in Figurel for clipping the tape between bag tops, as the bag tops are successively fed along between the dual pairs of belt runs 12 and 1 3.

Dual belt tensioning means Another important feature of the invention resides in the means provided for maintaining the dual belt runs 12 and 13 at the proper operating tension. Such a tensioning means is illustrated in Figures 4, 5 and 6. It c0m prises a pair of tension rods 66 and 67. The upper tension rod 66 is shown having one end pivoted to an arm 60 secured to the upper end ofa shaft 68, mounted for rocking movement in a bearing 69 in the machine frame, as best illustrated in Figure 6. Shaft 68 has an arm 71 secured to its lower end by a pin 72. Arm 71 is disposed in right angular relation to arm 60 at the upper end of shaft 63 and has a stud 73 secured thereto which rotatably supports pulley 14.

Pulley 14 at the front side of the machine is supported on a stud 74 having its upper end secured in an arm 75, as indicated at 76 in Figure 6. Arm 75 is secured to the lower end of a shaft 77 having an arm '78 secured to its upper end by suitable means, such as a set screw 79. Tension rod '66 has one end pivoted to arm 60, as indicated at 81 in Figure 5. The opposite end portion of rod 66 is slidably received in a guide 82 pivoted to arm 78, as will be understood by reference to Figure 5. A spring 83 is coiled about rod 66 and has one end seated against guide 82 and its opposite end against an adjusting nut 84 received in threaded engagement with rod 66, whereby arms 71 and 75 are constantly urged in a direction to tension co-acting belt runs 12-12.

The lower co-acting belt runs 13-13 are maintained at the proper operating tension by the tension rod 67, one end of which is pivoted to an arm 85 by a pivot pin or stud 86. The opposite end of rod 67 is slidably sup ported in a guide 87 and has a spring 88 coiled thereabout, one end of which is seated against guide 87 and its opposite end against an adjusting nut '89, secured to the threaded end portion of rod 67, as shown in Figure 5.

Guide 87 is pivoted to an arm 91 secured to a hub 92 mounted for pivotal movement on a sleeve 93, bored to receive a bolt 94 having its upper end received in threaded engagement with the machine frame, as indicated at 95 in Figure 6. A washer 96 is positioned between the bottom end of the sleeve 93 and the head of bolt 94,

G. whereby the sleeve may be non-rotatably secured in position so that the hub may rotate freely on the sleeve 93, as will be understood by reference to Figure 6. It is to be understood that the sleeve 93 is slightly longer than the hub 92, thereby to permit the hub to rotate freely on the sleeve 93 without binding.

The hub 92 has an arm 97 at its lower end disposed in right angular relation to the arm 91 at its upper end. Pulleys 15-15 are rotatably' supported at the outer ends of arms 97 and 98 by pivot pins or studs 99, as best illustrated in Figure 6. Suitable anti-friction bearings may be provided for supporting pulleys 14 and 15 upon their respective studs. Arm 98 is secured to a hub 101 in a manner similar to the way arm 97 is secured to hub 92. Ann 85, as shown in Figures 5 and 6, is secured to the- Belt heating means Another important feature of the present invention resides in the arrangement of the dual metallic belts 12 and 13 and the means provided for heating them to cause the plastic coating on the tape to become reactivated so that the tape walls may be intimately bonded to the bag top walls, as the bag tops successively pass through the bag top sealing mechanism.

To thus heat the dual belt runs, a plurality of heating bars are provided. Two such heating bars 102 and 103 are shown arranged in end-to-end relation at one side of the travel path of the bags, and four relatively shorter heating bars 104, 105, 106 and 107 are similarly arranged at the opposite or front side of the travel path, as best illustrated in Figure 2. Heating bars 102 and 103 are fixedly secured to the main supporting frame by suitable bolts 108, received in apertures provided in the supporting frame and having their lower .threaded terminals shown received in threaded engagement with the heating bars 102 and 103, as best illustrated in Figure 5.

Spacers 109 are interposed between heating bars 102 and 103 and the main supporting frame, as indicated in Figures 5 and 7. The lower ends of spacers 109 are preferably beveled at opposite sides, as shown at 111 in Figure 7, to reduce the transmission of heat from the heating bars 102 and 103 to the main frame. Each heat ing bar 102 and 103 has a heat-conducting plate or bar 112 secured to its inner face by bolts or screws 110. Heat-conducting bars 112 are longitudinally grooved, as shown at 113 in Figure 8 to permit free passage of the chain stitching at one side of the bag top, as will be understood by reference to Figure 8. The relatively shorter heating bars 104, 105, 106 and 107 are similarly provided with heat-conducting bars 114 secured to their respective heating bars by bolts 115. Said heat-conducting bars are longitudinally grooved, as at 129, shown in Figure 8, to clear the chain stitching at the front side of the bag tops,

To yieldably hold the heating bars 104, 105, 106 and 107 against the belt runs, said heating bars are mounted for independent movement so that they may yield to any irregularities occurring in the bag top walls, as the bag tops pass through the machine. Each of the relatively shorter heating bars at the front side of the travel path of the bag tops is shown having two shouldered studs ,116 secured thereto which project laterally therefrom Secured in threaded engagement with the outer end portion of each stud 116 is a nut 123, shown in Figure 4'. Nuts 123 are adjustably secured to the terminals of their respective studs 116, and provide seats for the forked terminals 124 of a plurality of flat spring elements 125, best illustrated in Figures 2 and 4. The intermediate portion of each spring element 125 is apertu-red to receive an adjusting screw 126 having its threaded end portion received in threaded engagement with the composite supporting bar or member 118, as will be understood by reference to Figure 4. The nuts 123 of studs 116 engage the forked end portions of the resilient elements 125 whereby said elements 125 constantly urge heating bars 104, 105, 106 and 107 in a direction towards the tape walls. Manipulation of adjusting screws 126 will vary the inward pressure of the movable heating bars against the dual belt runs 12 and 13, as will be understood.

Supporting bar 118 may be constructed of a plurality of flat members a, b and c, secured together in flatwise relation by the bolts 119 and a plurality of screws 121}, indicated in dotted lines in Figure 8. Members a and c extend the full length of the composite member or bar 118, whereas the intermediate members b are relatively shorter and serve as spacers between the top and bottom members a and c. It will also be noted that the intermediate members b have their ends spaced apart to provide the openings 1'17 for the studs 116. See Figures 7 and 8. If desired, supporting member 11-5 may be otherwise constructed as, for example, it may be formed from a single piece of bar stock in which case the openings 117 for the studs 116 would be drilled.

A spacer 128 is provided on each stud 116 between its nut 123 and the composite supporting bar 118 for limiting the inward movement of the heating bars, in the event such movement is to be limited. Each heating bar 104, 105, 106 and 107 has a heat conducting bar on plate 114 secured thereto by bolts 115, as will be understood by reference to Figure 8. From the foregoing, it will be noted that when the heating bars are secured in their respective positions in the machine frame, the opposed longitudinally extending grooves 113 and 129 in their respective heat conducting bars will permit free passage of the chain stitching between the heat conducting bars as the flattened bag tops are fed through the machine. It will also be noted that the dual pairs of belt runs 1213 and 12-13 at opposite sides of the travel path of the bag tops will engage the tape walls closely adjacent to the chain stitching, whereby the tape walls are pressed firmly into intimate bonding engagement with the bag top walls in close proximity to the chain stitching, whereby the needle holes are positively sealed against leakage.

- Means is provided for restraining the resiliently and floatingly mounted heating bars 104, 105, 1% and 197 against relative longitudinal movement in the machine frame, and is shown comprising a plurality of connecting links 132, 1135, 134 and 135, shown in Figures 1 and 7. Connecting links 132 and 133 each have one end pivotally connected to a common anchor pin 136, mounted in a bracket 137 secured to the supporting member 118 by suitable means such as welding. The opposite ends of links 132 and 133 are pivotally connected to their respective heating elements 104 and 105 by pivot pins 1139.

Belt cleaning elements 140 are prefenably provided for cleaning the metallic belts, as indicated on Figures 1, 2, and 4.

Heating bars 106 and 107 are similarly restrained against relative longitudinal movement by links 134 and 135, each having one end pivotally connected to a common anchor'stud 141 mounted in a bracket 142 secured to member 118, in a manner similar to heating bars 104 and 105.

Heating bars 102 and 107, inclusive, are electrically heated by suitable resistance elements, not shown in the nated' by the numeral 147, connected to a source of electric power, not shown.

Heating bars 104, 105, 106, and 107 are shown having conduits 148, 149,151 and 152, respectively, electrically connecting them to a junction box 153 which, in turn, is electrically connected to the control box 14-7 by a conduit 154. The two banks of heating bars are thermostatically controlled by suitable thermostats, indicated 155 and 156. The electrical system shown in Figure l is well known in the art, and it is therefore deemed unnecessary herein to describe the same in detail.

As hereinbefore stated, the present invention is not concerned with the sewing of the bag top walls. Its primary purpose is to provide means for hermetically sealing the bag tops as the bag tops are successively fed through the machine. This is accomplished by applying a thin, flexible, plastic coated strip of sealing tape over each sewn bag top and pressing the side wall portions thereof into firm bonding engagement with the bag top walls closely adjacent to the opposite sides of the stitching and securing said tape wall portions thereto by the application of heat and pressure, whereby the bag tops are positively sealed against leakage, even when roughly handled in transit.

The novel bag top sealing mechanism herein disclosed has been found extremely practical and eflicient in actual operation. By applying a strip of thermoplastic coated tape over the sewn bag top walls and bonding it thereto by the use ofthe dual heated belt runs, one belt run engaging the tape walls above the chain stitching, and the other directly below the chain stitching, the tape walls 'may be pressed into intimate bonding engagement with the bag top Walls close to the row of stitching, which is of utmost importance to eifect a positive seal. After thus bonding the tape walls to the bag top walls, the portions of the tape which overly the chain stitching are pressed firmly against the stitching and bag top walls by the compression rolls 28 and 29 thereby to complete the closing and sealing of the bag tops.

It is apparent that many modifications and variations of the invention as hereinbefore set forth may be made without departing from the spirit and scope thereof. The specific embodiments described are given by way of example only and the invention is limited only by the terms of the appended claims.

We claim as our invention:

1. In an apparatus for applying a strip of thermoplastic coated tape over the upper marginal edge portions of the walls of a bag top whose walls have previously been secured together in flatwise relation by a row of chain stitching extending the length of the bag top, means for guiding a strip of sealing tape over the top edge of each sewn bag top and folding the side wall portions thereof downwardly into flatwise engagement with the opposed wall surfaces of the bag top and whereby the tape overlays and conceals the chain stitching, pairs of dual belt runs cooperating to form a travel path for the bag tops, the belt runs of each pair of dual belt runs being vertically spaced apart to receive the chain stitching therebetween, heating means for pressing the belt runs of each pair of dual belt runs into engagement with the tape walls closely adjacent to the opposite sides of the chain stitching, thereby to heat and reactivate the tape walls and cause them to become intimately bonded to the bag top walls.

2. An apparatus according to claim 1 wherein means is provided for controlling the temperature of the heating means.

3. In an apparatus for applying a strip of thermoplastic tape over the upper marginal edge portions of the walls of a closed bag top whose walls have previously been secured together in flatwise relation by a row of chain stitching extending the length of the bag top, means for guiding the tape over the top edge of each sewn bag top and folding the side portions thereof downwardly into fiatwise engagement with the opposed wall surfaces of the bag top and whereby the tape walls overlay and conceal the chain stitching, co-acting pairs of dual belts cooperating to form a travel path for the bag tops, means at each end of the apparatus for supporting said pairs of dual belts whereby the belts of each pair of dual belts are vertically spaced apart to provide gaps therebetween for receiving the chain stitching, heating bars at each side of said travel path, and resilient means for pressing the heating bars at one side of said travel path into heating engagement with their respective belt runs.

4. In an apparatus for sealing a sewn bag top against leakage, a supporting frame, two pairs of single pulleys at the receiving end of the machine and a pair of dual pulleys at the discharge end of the machine, a plurality of endless metallic belts mounted on said pulleys and having certain runs thereof disposed in contiguous relation and cooperating to form a travel path for the bag tops to be sealed, means for folding a strip of sealing tape over each flattened bag top, the belts at each side of said travel path being arranged in pairs with the belts of each pair being vertically spaced apart to receive therebetween the chain stitching of each bag top, a plurality of heating bars for heating the belt runs forming said travel path, said heated belt runs softening and reactivating the thermoplastic coating on said tape, and resilient means for constantly urging said heated belt runs into engagement with the tape walls closely adjacent to the stitching thereof, whereby all needle holes in the bag top walls are hermetically sealed.

5. In an apparatus according to claim 4, wherein the pulleys of each pair of single pulleys at the receiving end of the apparatus are mounted for independent adjustment.

6. In an apparatus according to claim 5, wherein the corresponding belts at each side of the travel path of the bag tops are tensioned by a belt tensioning device which is common to said corresponding belts, thereby to assure uniform tension in said belts.

7. In an apparatus according to claim 6, wherein means is provided at the discharge ends of said belts for receiving and applying a final squeezing action to the sealed bag tops, thereby to press the tape walls firmly into bonding engagement with the bag top walls and the chain stitching, thereby to hermetically seal each bag top closure against leakage.

8. In an apparatus according to claim 5, wherein the vertically spaced pulleys of each pair of single pulleys at the receiving end of the apparatus are mounted for swinging movement in a horizontal plane about vertical axes, and means for independently tensioning the belts supported on said vertically spaced pulleys.

9. In an apparatus for hermetically sealing a closed bag top whose walls have previously been secured together in fiatwise relation by a row of stitching extending the length of the bag top, means for applying a flexible sealing element over the flattened bag top walls and folding the side wall portions thereof downwardly into engagement with the opposed wall surfaces of the bag top and over the row of stitching, a pair of dual belt runs on each side of the bag top, the belt runs of each pair of dual belts being vertically spaced apart to receive the row of stitching therebetween, and means for simultaneously pressing said dual belt runs into engagement with the walls of the sealing element closely adjacent to the row of stitching, thereby to intimately bond the walls of the sealing element to the bag top walls adjacent to the stitching to positively prevent leakage of the contents from the bag body through the needle holes of the stitching.

10. An apparatus according to claim 9, wherein a plurality of independently mounted heating elements are provided for yieldably retaining the dual belt runs in engagement with the walls of the sealing element, and whereby the belt runs may follow the contour of the bag top walls as the bags pass through the apparatus.

11. An apparatus according to claim 10, wherein the heating means for the belt runs comprises an elongated fixed heating bar located at one side of the travel path of the bag tops and a plurality of relatively shorter heating bars arranged in end-to-end relation at the opposite side of said travel path, said heating bars cooperating to press the heated belt runs into intimate engagement with the walls of the sealing element directly above and below the row of stitching.

12. In an apparatus for hermetically sealing a closed bag top whose walls have previously been secured together in flatwise relation by a row of stitching extending the length of the bag top, means for applying a flexible sealing element over the flattened bag top walls and folding the side wall portions thereof downwardly into engagement with the opposed wall surfaces of the bag top and over the row of stitching, an elongated fixed heating bar located at one side of the travel path of the bag tops, and a plurality of independently mounted relatively shorter heating bars arranged in end-to-end relation at the opposite side of said travel path, said shorter heating bars yieldably retaining the dual belt runs in engagement with the walls of the sealing element permitting said dual belt runs to follow the contour of the bag top walls directly above and below the row of stitching, as the bags pass through the apparatus.

References Cited in the file of this patent UNITED STATES PATENTS 2,097,449 Cundall Nov. 2, 1937 2,362,462 Belcher Nov. 14, 1944 2,447,014 Irmscher Aug. 17, 1948 2,845,760 Hopkins Aug. 5, 1958

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