US3286433A

US3286433A - Bag top sealing machine and method for forming a bag top closure

Info

Publication number: US3286433A
Authority: US
Inventors: Harold K Johnson; Richard H Ayres
Original assignee: Bemis Co Inc
Current assignee: Amcor Flexibles North America Inc
Priority date: 1963-02-14
Filing date: 1963-02-14
Publication date: 1966-11-22
Anticipated expiration: 1983-11-22

Description

Nov. 22, 1966 H. K. JOHNSON ETAL 3,236,433

BAG TOP SEALING MACHINE AND METHOD FOR FORMING A BAG TOP CLOSURE 4 Sheets-Sheet 1 Filed Feb. 14, 1963 a N MWSm 4 4 y J mm a g HY mh BMW Nov. 22, 1966 H. K JOHNSON ETAL BAG TOP SEALING MACHINE AND METHOD FOR FORMING A BAG TOP CLOSURE 4 Sheets-Sheet 2 Filed Feb. 14, 1965 I 11 I l I IUII' I s v N fi 50$ R 5 E 2 mwwwm NJ 7 V M I? 4 K D m MW MK HR M Y 1 B I Nov. 22, 1966 H. K. JOHNSON ETAL BAG TOP SEALING MACHINE AND METHOD FOR FORMING A BAG TOP CLOSURE 4 Sheets-Sheet 5 Filed Feb. 14, 1963 Tm HNJHN A freewa s INVENTOR S Wq-Wutam.

Nov. 22, 1966 H. K. JOHNSON ETAL 3, 33

BAG TOP SEALING MACHINE AND METHOD FOR FORMING A BAG TOP CLOSURE 4 Sheets-Sheet 4 Filed Feb. 14, 1965 5 ,n m H mm M mwmfi m n? 7 m 4 0 MW. M, n a

FIG. 5

United States Patent 3 286,433 BAG TOP SEALING MACHINE AND METHOD FOR FORMING A BAG TOP CLOSURE Harold K. Johnson, Bloomington, and Richard H. Ayres,

Minneapolis, Minn., assignors to Bemis Company, Inc.,

a corporation of Missouri Filed Feb. 14, 1963, Ser. No. 258,446 11 Claims. (Cl. 5339) This invention is related to new and novel apparatus for heat sealing a bag top of a filled bag, for example polyethylene bags, to form a bag top closure. More particularly this invention is related to new and novel apparatus for trimming a bag top and directing hot air against 0pposite trimmed top edge portions of a filled plastic bag made of, for example, polyethylene to form a bag top closure on the bag and method for forming a heat seal bead bag top closure.

There are a number of different methods presently available for heat sealing polyethylene bags to form a bag top closure, the most common method utilizing heater bars with steel bands to carry the bag top between the heater bars. In utilizing this method, the heat is transmitted from the heater bars through the steel bands to a bag top. Such methods have a number of disadvantages. For example in utilizing a steel band, the bands actually compress the polyethylene as it is heated and thus weaken the seal. This effect is even more pronounced when the bags are of a gusseted type. Additionally, contamination is relatively critical with the steel band method, the contamination resulting in weakened areas in the seal. Further, a relatively large unit is required while various adjustments and temperature are very critical in comparison to the criticality of such factors in the method and apparatus of the invention described hereinafter.

One of the objects of this invention is to provide a new and novel method for forming a top closure seal on a filled plastic bag and apparatus for carrying out said method. Another object of this invention is to provide new and novel apparatus that blows hot air against opposite top edge portions of a filled plastic bag to form a bag top heat seal head. A further object of this invention is to provide new and novelapparatus for trimming a bag to a predetermined elevation and then forming a heat seal seam along the trimmed edge portions.

Still another object of this invention is to provide new and novel apparatus for trimming the bag top edges and then forming a heat seal seam through the use of hot air as the bag is being conveyed in a given direction. A still further object of this invention is to provide new and novel apparatus that may be utilized for heat sealing bags of different gauge material and which will trim the top edges to a determined elevation, clean the trimmed upper edges of the bag top and thence form a heat seal seam along the trimmed bag top edge portion.

Other and further objects are those inherent in the invention herein illustrated, described, and claimed and will be apparent as the description proceeds.

To the accomplishment of the aforegoing and related ends, this invention then comprises the features hereinafter fully described and particularly pointed out in the claims, the following description setting forth in detail certain illustrative embodiments of the invention, these being indicative, however, of but a few of the various ways in which the principles of the invention may be employed.

3,286,433 Patented Nov. 22, 1966 The invention is illustrated by reference to the drawings in which the same reference numerals refer to the same parts and in which:

FIGURES 1A and 1B when fitted together along the line XX with an appropriate reduction in the scale of FIGURE 1B forms a plan view of the bag top sealing machine of this invention, other than that the control housing is not shown and portions are broken away to more clearly illustrate other structure;

FIGURES 2A and 2B when fitted together along the line YY together with an appropriate reduction in scale of FIGURE 2B form a vertical side elevational view of the bag top heat sealing machine of this invention (the heat seal housing not being shown);

FIGURE 3 is a transverse cross sectional view generally taken along the line and in the direction of arrows 33 of FIGURE 1A to more fully illustrate the construction of the mechanism for heating air and the structure adjacent the forward transverse support;

FIGURE 4 is an enlarged, fragmentary transverse sectional view generally taken along the line and in the direction of arrows 4-4 of FIGURE 1A to more fully illustrate the structure utilized in cleaning the trimmed bag top edge portions and structure for adjustably retaining the bag top conveyor belts in position to supportingly hold the trimmed bag top at the desired elevation;

FIGURE 5 is a still further enlarged fragmentary horizontal view illustrating the bag top opening bar spreading the bag top edge portions, said view being generally taken along the line and in the direction of the arrows 55 of FIGURES 4 and 6;

FIGURE 6 is a fragmentary longitudinal view of structure of FIGURE 5, said view being taken along the line and in the direction of the arrows 6-6 of FIGURE 5;

FIGURE 7 is an enlarged fragmentary transverse sectional view generally taken along the line and in the direction of arrows 77 of FIGURE 1A to illustrate the mounting of the hot air bars and the construction of said bars, part of the mounting bracket and the girts being broken away;

FIGURE 8 is an enlarged transverse sectional view generally taken along the line and in the direction of arrows 88 of FIGURE 1B to more fully illustrate the mechanism for trimming the bag top;

FIGURE 9 is a simplified wiring schematic of the control mechanism and circuitry of this invention; and

FIGURE 10 is a fragmentary cross sectional view of a bag top closure formed by a modified form of the machine.

Referring now in particular to FIGURES 1A, 1B, 2A, 2B and 3 there are illustrated a plan view, a side vertical elevational view, and a transverse sectional view of the bag top sealing machine, generally designated 10, of this invention in conjunction with a fragmentary illustration of the pedestal assembly 11 for supporting the machine 10 in overhanging relationship to a conveyor 12. (see FIGURE 4) that extends the longitudinal length of the machine 10 to support the bottom of a filled bag 14 as it is conveyed through the bag top sealing machine. The bag top sealing machine includes a longitudinally extending frame 15; a bag top conveyor assembly 16 for holding the bag top sidewalls closely adjacent one another at the proper elevation relative to the conveyor 12 while the bag top is moved through the machine; a bag top trimming assembly 17 mounted on the forward end of the frame to trim off the excess bag top before the bag top seal bead is formed; a bag top cleaning assembly 18 for cleaning off material which would contaminate the heat seal bead off the adjacent edges of the bag top that are subsequently sealed together; a bag top seal forming assembly 19 for forming a top closure heat seal bead on the filled bag and control mechanism 20 for the machine.

The frame is mounted on a pedestal assembly 11 which includes a pair of longitudinally spaced horizontally extending support rods 22 mounted by a support bracket 23 to extend outwardly therefrom (see FIGURES 2A and 3). The support bracket 23 in turn is mounted on the upper end of the elevating column 24, the elevating column being mounted by a pedestal base (not shown) to be adjustably positioned in a vertical direction by mechanism not shown. Since the pedestal assembly is a conventional item and does not form a part of this invention, it will not be further described.

For purposes of facilitating the description of machine 10, the vertical plane of conveyance of the bag top of bag 14 through the machine will be referred to as the central longitudinal axis LL of the machine, a location in a horizontal direction at right angles to said plane as transversely outwardly (right or left), the end of the machine where the bag enters as the forward end, and the end where the bag exits from the machine as the rear or back end. Thus as the bag top moves through the machine it is considered as being moved in a rearward direction.

The main frame includes a longitudinally extending angle iron 27 that mounts a pair of annular mounting members 28 in depending relation thereto for being mounted on the respective support rod 22. Set screws (not shown) are provided for holding the mounting members 28 in a transversely adjusted position on the support rods. Welded to the vertical leg of the angle iron to ex tend thereabove is a longitudinally extending main support plate 29, the upper end of the support plate being bent to form an inwardly extending horizontal flange 29a. Bolted at 27 to the rear end portion of the main support plate is a vertical, generally transversely extending drive end (rear) support 30 while to the front vertical edge portion of the main support plate there is bolted a second vertical transverse support 31, each of the

supports

30 and 31 have angle reinforcing portions. Each of the

supports

30 and 31 extend transversely from the main support plate inwardly to the axis LL and thence outwardly a substantial distance on the other side of axis LL (see FIGURES 1A and 1B).

A right side girt 32 and left side girt 33 extend longitudinally between the

supports

30 and 31 in transverse spaced relationship to one another, one on either side of axis LL. The aforementioned girts have generally horizontal legs 32a and 33a, vertical legs 32b and 33b respectively and vertical flange members 320 and 330 at either end that are bolted by bolts 34 to the lower central portion of adjacent transverse support.

A support bracket 40 having a back wall 40a is at its back wall bolted to the lower central portion of the support 31 on the side opposite

girts

32, 33 to extend forwardly thereof. The support bracket also includes a horizontal bottom wall portion 40d joined at its rear edge to the lower edge of the back wall and a second bottom wall portion 40c likewise joined to the back wall 40a. The bottom wall portions are of a size and located to have their adjacent inner longitudinal edges in spaced relation on either of the axis LL to form a throat 44 that extends the longitudinal length of the support bracket 40. Further as may be noted in FIGURE 3 the support bracket is mounted on the support 31 to have the bottom wall portions located at a substantially lower elevation than the girt horizontal legs 32a and 33a. Cut

outs

46 and 47 are formed in the lower central portion of the support 31 and back wall 40a respectively, said cutouts having contiguous edges other than for edge portions in the support 31 which extend to a substantially lower elevation than

bottom wall portions

40d and 40e. As may be noted in FIGURE 3 the side edges of the cutouts are inclined inwardly in an upward direction while the top edges are rounded and located at an elevation substantially above the horizontal legs of the girts.

The bracket 40 also has an angle reinforcing flange 40!) joined at respective edges to the back wall 401: and wall portion 40c and a similar flange 40c joined at respective edges to wall 40a and wall portion 40d. A U-shamfl bracket 49 is provided adjacent the front portion of bracket 40, the lower ends of the legs of the bracket 49 being welded to wall portions 40d and 40:: respectively.

Members

40b, 40c and 49 serve to rigidly hold

portions

40d and 40e in spaced relation.

The structure of the frame 15 having been generally set forth, the bag top conveyor assembly 16 will now be described. The assembly 16 includes a mount 52 that journals a pair of vertically extending shafts 53 and 54 in transverse spaced relationship, the mount being welded to the rear central portion of the support 30 (see FIG- URES 1A and 2A). Keyed to the upper end of the shaft 53 is a tooth gear 58 having a chain 55 extended there around for driving said shaft. The chain 55 is extended through an opening in plate 29 and then around a tooth gear 56 that is keyed to the motor shaft 57 of the motor '51. The motor is mounted on a motor mount 59 which in turn is attached to the rearward end portion of the main support plate transversely opposite the shaft mount 52.

Keyed to the shaft 53 intermediate gear 58 and mount 52 is a tooth gear 56, the gear 56 being mounted in intermeshing relationship with a second tooth gear 56 keyed on shaft 54. Keyed on the lower end of each of the shafts 53 and 54 are pulley sheaves 57, there being a pulley belt 60 extended around the shaft 54 pulley sheave and a similar pulley belt 61 around the pulley sheave on shaft 53. Thus motor 51 is drivingly connected to shaft 53, the shafts 53, 54 being rotated in opposite directions through gears 56 to cause the belts 60, 61 through th sheaves 57 to be driven in opposite directions.

Mounted on the forward end portions of each of the

bottom wall portions

40d and 40e of the support bracket to extend there above is a vertical stud shaft 62, the stud shafts in turn rotatably mounting pulley sheaves 63 and 64 respectively at an elevation slightly above the respective wall portion. The pulley sheaves each have a pair of vertically spaced pulley grooves. The lower half of pulley sheave 63 has the belt 60 drivingly extended there around while the lower half of pulley sheave 64 has the belt 61 drivingly extended there around whereby said sheaves are drivingly rotated in opposite directions.

Referring now in particular to FIGURE 3, there is provided for belt 60 an idler pulley assembly having a pulley sheave 66 rotatably mounted in depending relation to the pulley bracket 67 by a stud shaft 68. The pulley bracket is bolted to the rearward side support 31 and is provided with a transversely elongated slot 67a to permit transverse adjustment of the stud shaft 68 (see FIGURE 1A). In this connection it is to be mentioned that the upper end of the stud shaft is threaded whereby a nut may -be threaded thereon and loosened to permit transversely adjusting th stud shaft.

As may be noted from FIGURES 1A, 1B and 3 the outer run 60a of the belt in passing over the pulley sheave on shaft 54 extends in a divergingly outwardly forward direction to pass through a cutout (not shown) in the lower portion of the support 30 and passes over the pulley sheave 66 to have its inner surface contact said sheave. The outer run then converges transversely inwardly in a forward direction to pass through cutout 69 formed in the support 31 adjacent the lower outer corner portion of said support (see FIGURE 3), and thence extends over the pulley sheave 63. The belt 60 then extends in a rearward direction to have its inner run 60b extend generally in a straight line other than for limited divergencies resulting from adjustably positioning the belt guides and other structure which will be described hereinafter. As a result the belt 60 may be properly tensioned by making proper adjustments of the idler pulley assembly as described heretofore.

The wall portion 40a has an outwardly projecting ear 40) that mounts an upright stud bolt 101, the stud bolt being extended through a transversely elongated slot in the wall portion for limited transverse adjustment. A bushing 102 is provided on the stud bolt to have the outer run 61a of the belt 61 hear there against. Since the stud bolt is adjustably held in a transversely elongated slot, the belt 61 may be adjustably tensi-oned.

As the bushing 102 is located a greater transverse distance from the central longitudinal distance L-L of the machine than the pulley sheaves 64 and the pulley sheave on shaft 53 the outer run 61a converges from bushing 102 toward said central axis in a rearward direction to pass through cutout 72 and over the pulley sheave on shaft 53 and in a forward direction to pass over pulley sheave 64, the last mentioned pulley sheaves positioning the inner run 61b to extend in a generally straight line between said sheaves and closely adjacent the run 60b other than for belts, guides and other structure to be described.

In order to supp-ortingly hold the inner runs of the belts 60 and 61 closely adjacent one another but at the same time permit limited transverse adjustment thereof, there are provided elongated right and left belt guides 76 and 77, respectively, said belt guides being generally U-shaped in transverse cross section (see FIGURE 4). The belt guides each include a pair of longitudinally spaced transversely extending ear portions 76a and 77a respectively, said ears each having a vertical aperture formed therein to have a pivot member 79 extended therethrough for pivotally supporting the respective ear in the bifurcated end of the belt guide stud 80. The belt guide studs connected to the guide 76 extend transversely outwardly from the central longitudinal axis L-L through appropriate apertures formed in the vertical leg 33b of a girt 33 and thence through an aperture formed in the lug 85 that is dependingly welded to the outer transverse edge portion of a horizontal leg 33a. As may be noted in FIGURE 2A there are provided two lugs 85 in longitudinal spaced relationship on the girt 33. The outer end of each belt guide stud is threaded to have a nut 81 threaded thereon while a retainer ring 82 is press fitted on intermediate portion of the belt guide stud to be closely adjacent the vertical leg of the girts 33. A second retainer ring 83 is slid-ably mounted on the belt guide stud, there being provided a coil spring 84 having one end seated against the retainer ring 83 and the opposite end seated against the retainer ring 82 to thereby resiliently urge the belt guide stud 80 of girt 33 transversely inwardly toward the central axis LL. However, the transverse inward movement of the belt guide 76 is limited by the position of the nut 81 on the stud 80.

The structure for adjustably mounting belt guide 77 is the same as that for mounting the guide 76 other than that the belt guide studs 80 for the guide 77 extend transversely outward from the central axis LL through the vertical girt leg 32b and thence through apertured lugs 85. The last mentioned lugs are located transversely outwardly of the leg 32b and are welded to the horizontal girt leg 32a to depend therefrom. As a result, the transverse position of the belt guide 77 likewise can be adjusted by appropriately threading the nuts 81 on the studs 80, which are pivotally connected to the guide 77 whereby the inner runs 60b and 61b are resiliently held in sufilciently tight abutting relationship to supportingly convey a bag top without movement relative to the belts.

The belt guides 76, 77 are located intermediate the

supports

30 and 31 and are of longitudinal length to extend closely adjacent each of the supports. Portions of the belt guides located intermediate the forward lugs and the support 31 are bent a few degrees to diverge slightly transversely outwardly of one another in a forward direction.

Mounted on the

bottom wall portions

40d and 40e of the support bracket 40 to overlie said wall portions are generally channel shaped belt guides 88 and 89 respectively (see FIGURE 1B). Welded to the lower leg of each belt guide at opposite longitudinal end portions thereof is a lug 90, each lug having a transversely elongated slot therein (not shown) through which a bolt 91 is extended and thence threaded into an appropriate aperture in the respective bottom wall portion. By loosening the bolts 91, the guides may be transversely adjustably spaced. Referring to FIGURE 1B, the

guides

88 and 89 are positioned to in normal operation retain the inner runs of the belt in overlaying relationship relative to the throat 44 and in abutting relationship.

A description of the bag top conveyor assembly having been set forth, the bag top trimmer assembly 17 will now be described (see in particular FIGURES 1B, 2B and 8). The assembly 17 includes the upper pulley sheave portions of pulleys 63 and 64 and pulley sheaves 93, 98, which are generally of the same construction as pulley sheaves 63 and 64. Pulley sheave 93 is rotatably mounted on a stud shaft 94 which in turn is mounted on the bottom wall portion 40c intermediate the belt guide 89 and the pulley sheave 64. The stud shaft 94 positions the pulley sheave 93 to have one circumferential portion overlie the throat 44.

A belt 96 is extended around the upper half of pulley sheave 64 to be driven thereby, thence extends rearwardly over the upper groove of the pulley sheave 93, and thence transversely outwardly to pass around the pulley sheave 95 that is rotatably mounted on the stud shaft 101, the bushing 102 being located intermediate the bottom wall portion 40c and the pulley sheave 95. Accordingly, the inner run 96a of the belt 96 substantially overlies the adjacent portion of run 61b, but is vertically spaced therefrom as indicated in FIGURES 2B and 8.

A second belt 99 is extended around the upper grooved portion of the pulley sheave 63 to be driven thereby and thence extends rearwardly to have one run pass over the upper grooved portion of pulley sheave 98, pulley sheave 98 being rotatably mounted on a stud shaft 100 and transversely spaced about the same distance from throat 44 as stud shaft 94 but on the opposite side thereof. A pulley sheave 106 is rotatably mounted on the upper end of a stud bolt 107, the stud bolt being mounted on a bottom wall 40a, and extending through a transversely extending slot (not shown but same as slot 104 for stud bolt 101). As may be noted

sheaves

95 and 106 are closely adjacent one another. A bushing 108 is provided on the stud shaft intermediate pulley sheave 106 and the bottom wall portion 402. As may be noted in FIGURE 1B, the pulley sheaves 63, 64, 93, 98, 95 and 106 are positioned so that the runs 96a and 99a of the

belts

96 and 99, respectively, at the forward end of the machine are spaced to form a throat but

adjacent sheaves

93 and 98 are held in abutting relationship. The belts thence are curved to extend transversely outwardly in abutting relationship in a left-hand direction along runs 96b and 9% respectively. Thus, the runs 96a and 99a pass through the nip betwen pulley sheaves 93 and 98 and thence as the belts extend transversely outwardly, they are held in abutting relationship since they are at the same vertical elevation. Purpose of mounting the belts in the aforementioned manner will become apparent hereinafter.

In addition to providing transversely elongated slots 104 to permit limited transverse adjustment of

sheaves

95 and 106, the stud bolt 100 is extended through a transversely elongated slot (not shown) and stud shafts 62 are each extended through longitudinally elongated slots (not shown) to permit limited adjustment in the corresponding directions of elongation of the respective slots. As a result of providing such slots and the idler pulley assembly, the

belts

60, 61, 96 and 99 may be properly tensioned.

Mounted on the bottom wall portion 40c intermediate U-shaped bracket 49 and pulley sheave 93 is a knife mounting plate 109 while on the bottom wall portion 40d there is provided a second knife mounting plate 110. For the aforementioned knife mounting plates there are provided clamp plates 111 and 112, respectively. Bolts 113 are extended through appropriate transversely elonigated apertures formed in each of the knife mounting plates and the clamping plates and are secured to the respective bottom wall portion for clampingly retaining the knife 114 which is positioned between the clamping plates and the knife mounting plates. The aforementioned knife advantageously may be a razor blade that is held by the aforementioned plates to extend diagonally across the throat 44 with the cutting edge facing in a forward direction. The aforementioned knife mounting members retain the blade at an elevation slightly lower than a bottom edge of the inner runs 96a and 99a of the respectively belts.

The knife mounting plates and clamping plates have adjacent vertical surfaces that are generally planar and are mounted on the bracket 40 to hold the adjacent inner runs of

belts

60, 61 and 93, 99 respectively in abutting or substantially abutting engagement, whereby a bag top will be held against movement relative said belts as it is cut by the knife.

The trimmer assembly having been described, the structure of the bag top cleaning assembly 18 will now be set forth (see FIGURES 1A, 2A, 4, and 6). The assembly 18 includes a right angle bracket 140 having transversely elongated slots 144 formed in the horizontal leg thereof through which bolts 141 are extended for mounting the bracket on the left girt 32, the slots permitting limited transverse adjustment of the bracket. Welded to the leading edge of the horizontal leg of bracket 140 is a horizontally extending bag top opening rod 142, the rod being mounted to extend across the inner runs of both belts 60 and 61 and at a slightly higher elevation than the top surfaces of said belts, but at a lower elevation than the cutting edge of the knife 114.

The bracket 140 has an upwardly extending leg 14% that mounts a short stud shaft 143, the stud shaft in turn rotatably mounting a narrow width brush 144 to rotate about a transverse horizontal axis. As may be noted from FIGURES 4-6, the brush 144 is positioned to have one circumferential bristled portion thereof extend to approximately the same elevation as the lower surface portion of the bag top opening rod at a position rearwardly of said bar. Further as may be noted from said figures the brush is positioned to be directly vertically above the adjacent surface portions of runs 60b and 61b.

In order to drivingly rotate the brush 144 in the direction of arrow 145 there is provided an air nozzle 146, the outlet end of said air nozzle being located adjacent the top circumferential portion of the brush 144 as shown in FIGURE 2A. The opposite end of the air nozzle is fluidly connected to one end of the fluid line 147, the opposite end of said line being connected to a pressurized source of air 161 (see FIGURE 1A). A valve 162 is provided in the line 147 to regulate the flow of air through said line.

The nozzle 146 mounted on a transversely extending rod 149 by a clamp member 148 there being provided a set screw (not shown) for retaining the clamp member in a transversely adjusted position on the rod 149 and at the desired angle of inclination. The opposite end of the rod is welded to clamp 150 which in turn is mounted on the vertical rod 151. The clamp 150 has a vertical aperture through which rod 151 is extended and has a bifurcated end portion opening to said aperture. A bolt 15012 is extended through apertures in the bifurcated portion and has a nut threaded thereon so that clamp may be clampingly retained in a vertically adjusted position on the rod 151. The lower end of the rod 151 is welded to a plate 152 which has longitudinally elongated apertures formed therein through which bolts 153 are extended and threaded into appropriate apertures in the girt leg 33a. Due to the provision of the elongated apertures in the plate 152, the plate and the structure thereon may be adjustably positioned in a longitudinal direction a limited amount to appropriately space the outlet end of the nozzle from the brush 144 while the clamp 150 permits limited vertical adjustment of the nozzle and the clamp 148 permits limited transverse and rotational adjustment of said nozzle. Thus elements 148153 provide means for adjustably positioning the nozzle so that the exit of air therefrom drives brush 144. Thus the nozzle in effect provides an air motor for driving said brush, it being understood that a conventional air motor could be mounted on the bracket 140 and have the brush keyed on its motor shaft to be driven thereby in place of the structure described. However, the air jet drive has a definite advantage over the use of an air motor since in addition to driving the brush, the air from the jet also follows the brush around and blows free the dust or contamination loosened by the brush.

The bag top cleaning assembly 18 having been described, the structure of the bag top seal forming assembly 19 will now be set forth (see FIGURES 1A, 2A and 7). The assembly 19 includes a generally T-shaped bracket having a cross bar plate bolted to the main support plate, said plate having elongated slots through which bolts 171 are extended to permit limited vertical adjustment of the bracket 170. The center leg 17% of the bracket 170 extends transversely from the cross bar plate to overlie the girt 32. The inner end portion of leg 17% is bifurcated and has a vertical aperture formed therein for receivingly mounting the vertical rod portion 172a of the hot air bar mounting member 172, there being a clamp bolt extended through appropriate apertures to tighten the bifurcated branches of member 172 to clampingly hold the vertical rod portion.

The mounting member 172 also has horizontally extending bar 172b which is formed integral with the lower end of the rod 172a, the bar in turn mounting a pair of longitudinally spaced horizontal slide rods 172c in parallel relationship. As may be noted in FIGURES 1A and 7, the slide rods extend transversely across the space between the girts and are located vertically above said girts.

Sli-dably mounted on the rods 1720 in transverse spaced relation are longitudinally enlongated hot air bars 174 and 175 respectively, there being a bar on either side of the central axis L-L in transverse spaced relationship thereto. Each of the hot air bars has a removable bottom cover plate 176 to provide an enclosed plenum chamher 177 that extends substantially the entire length of the bars. An elongated slot 178 opens from the respective plenum chamber to direct hot air in a transverse direction toward the central longitudinal axis L-L, the slots 178 being of a very small height and elongated in a longitudinal direction to extend the length of the respective plenum chamber. Also formed in the hot air bars are inlets 179 that open to the respective plenum chamber, one end of a flexible air hose 180 being attached to bar 174 to open through inlet 179 to the respective plenum chamber while one end of a similar hose 181 likewise opens to the plenum chamber in bar 175. The opposite ends of

hoses

180, 181 are fluidly connected through elbows 182, 184 respective to opposite legs of the T-joint 183.

The third leg of the T-joint 183 is fluidly connected to one leg of a T-joint 188, T-joint 188 being mounted on the one end of the transversely extending pipe 189. The opposite end of the pipe extends through an aperture in the main support plate and thence is connected by the elbow 190 to the hot air heating mechanism generally designated 21. The third leg of the T-joint 188 mount-s a tubular mounting member 192 that in turn mounts a thermometer 191, the thermometer having leads (not shown) that extend through members 190, 188 and 189 to a position adjacent the hot air heating mechanism in order to measure the temperature of the air leaving said mechanism.

In order to minimize the loss of heat there is provided a generally box shaped housing 195 that encloses elbows 182 and 184, T-

joints

183, 188, and a portion of the pipe 189. The aforementioned housing includes a removable cover member 105a and has appropriate apertures formed in the walls thereof to provide for making the previously described connections to the members in the housing. The housing 195 at one end is mounted on the main support 29 rearwardly of the T-bracket 170 and has insulating material (not shown in the housing to surround the members mounted in said housing).

The heating mechanism 21 includes a generally rectangular box shaped fin tube casing 201 having a removable top cover 202, said casing being mounted on the angle bracket 27 to sit on the horizontal leg thereof (see FIG- URES 1A and 3). Mounted within the fin tube casing to extend substantially the longitudinal length thereof is a fin tube housing. The fin tube housing includes a pair of longitudinally extending

tubes

204 and 205 that are welded together in abutting relationship. One longitudinal end of each of the aforementioned tubes extend through appropriate apertures formed in the end wall of the generally box shaped member 206 and welded thereto while the opposite ends of the tubes are welded to and extend through apertures formed in a wall of box member 207. As may be noted from FIGURE 1A, the opposite ends of the

box members

206 and 207 open to the adjacent end walls of the fin tube casing 201, the box members supporting the tubes in spaced relation to the side walls, bottom wall, and cover of the fin tube casing. Mounted in each chamber formed by the

box members

206 and 207 is a fin tube cover plate 209 that closes the open ends of the tubes other than for the apertures 208a and 20% which are of a substantially smaller diameter than the inside diameter of the respective tube into which said apertures open.

An electrical heater element 211 is mounted in a fin tube 225 located within the tube 204 while a second heater element 212 connected in parallel with element 211 is mounted in the fin tube 226 which in turn is mounted in the tube 205 (see FIGURE 9). The aforementioned heater elements and fin tubes extend outwardly through the respective apertures 209a and 2091) of the cover plates 209 while the leads of said elements thence extend through the chamber of box member 206 and outwardly through the apertures 213 and a corresponding aperture (not shown) formed in the cover 202. The combination of a heater element and fin tube is a stock item, the fin tube being of a construction having a spiral fin formed integral with the exterior circumferential surface of a tube to extend the length thereof except for either axial end portion. As a result the combination of, for example, tube 204 and fin tube 225 form a spiral air passage 225a within tube 204.

In order to provide air to be heated in

tubes

204 and 205, a line 217 at one end is connected through a valve 220 to the pressurized source of air 161 while the opposite end is connected through the' elbow 218 to the boss 219 that is welded to the

tubes

204 and 205 to open into the interior of both of said tubes such as shown in FIG- URE 3. The boss 219 is located a short distance rearwardly of the box member 206. Air flows through an elbow 218 into the spiral passageways to be heated, the heated air existing from the

tubes

204 and 205 through an outlet boss that is connected to the tubes adjacent but forwardly of the box member 207 in a manner correspond- 10 ing to that illustrated in FIGURE 3. The outlet boss in turn has the elbow connected thereto. Insulating material (not shown) is placed in the casing 201 to surround the structure previously described as being located in said casing.

Referring now particularly to FIGURE 9, the electrical components and circuitry, generally designated 20, will now be described, it being understood that most of the electrical control elements other than heater elements and leads are located in the control housing (not shown) which is mounted above the heater element casing. The electrical components and circuitry 20 includes main power lines L1 and L2, power line

L1 having junctions

231, 232 formed thereon while the power line L2 has

junctions

233, 234 and 235 formed thereon. A fuse 236 is located in each of the power lines such as illustrated in FIGURE 9.

A pressure actuated switch 237 is connected across

junctions

231 and 238, said switch having an operative linkage 239 extending into the air stream passing through either the tube 204 or tube 205, or the inlet or the exit passageway from said tubes. For convenience, the connection is illustrated as extending into the passageway in tube 204. The pressure actuated switch is of the type that it is normally in open position, however upon airflow exerting a force against the operative connection 239, the switch is moved to a closed position to electrically connect junction 231 to junction 233, but to break said connection upon the cessation of airflow. The reason for providing this switch will become more apparent hereinafter.

Connected across

junctions

238 and 242 is a manually operated on-off switch 241, switch 241 being of the type that is resiliently retained in an open position but upon being manually depressed will establish electrical connection between

junctions

238 and 242. Connected across

junctions

242 and 243 is a stop reset switch 244, switch 244 being of the type that is resiliently retained in an on position, however upon being manually depressed will break the electrical connection between

junctions

242 and 243.

A solenoid coil 245 of a starter relay is connected across

junctions

243 and 233, the starter also including a first terminal 246, a second terminal 247, a third terminal 248 and a fourth terminal 249. Terminal 246 is connected by line 250 to junction 242 while terminal 247 is connected by line 251 to junction 238. A normally open switch member is provided to be operated by the energization of coil 245 to electrically connect

terminals

246 and 247 but to break this connection when coil 245 is de-energized.

The center variable lea-d 253 of the powerstat 254 is connected to terminal 249 of the starter, the powerstat at one end being connected to junction 232. The outer variable lead 255 of the powerstat is connected to junction 235. Also electrically connected to junction 235 is one end of the heater element 211, the opposite end of said element being connected to junction 256. Also junction 256 is connected by a line 257 to junction 258, one end of the heater element 212 being connected to junction 258 and the opposite end being connected to junction 234. Junction 258 is also connected by line 259 to terminal 248.

The starter also includes a normally open switch mean- =ber that upon energizati-on of coil 245 moves to electri cally con-nect terminals 248 and 249 to thereby apply power to the heater elements 211 and 212 but upon be ing tie-energized breaks the electrical connections to said heater elements. As a result of providing the aforementioned circuitry the heater elements may be energized only when air is flowing through the spiral passages, this resulting from the provision of the pressure actuated switch which prevents the heater elements burning out by being overheated.

In order to vary the temperature of the air exiting through pipe 189, the powerstat may be varied in a conventional manner. Normally the powerstat is adjusted 1 1 so that the air exiting through pipe 189 is of a tempera ture range 400-500 F.

Also to be mentioned is that a separate control circuit-ry (not shown) is provided for energizing motor 51 and that a separate drive motor and control circuitry is provided for driving the conveyor 12, the upper run of the conveyor being driven at the same speed as runs 60b, 61b, 96b and 99b of the respective belts. Since such circuitry is conventional and does not form part of this invention it will not be described.

The structure of the apparatus of this invention having been described, the operation thereof will now be set forth. Before using the machine the bag top guides are appropriately adjustably positioned for the gauge material of the bags to be heat sealed and as to whether the bag top is of a gusseted type or a non-gusseted type. That is the bag top guides are adjustably spaced so that the inner runs of the belts 60 and 61 will firmly supportingly hold the bag top side walls in abutting relationship to one another. Likewise the knife mounting members are transversely positioned. Additionally the hot air bars are adjustably positioned (vertically and transversely) for the desired bead thickness, the vertical lowering of the hot air bars giving a thicker bead.

Also another preliminary step is to vertically adjust the pedestal assembly so that a filled bag being carried by the upper run of conveyor 12 will have its bag top edges located at .a proper elevation relative the knife. Now the motor 51 is actuated to drive the respective mem bers driven thereby and

valves

162 and 220 are opened to give the proper flow rate of air. The flow of air through lines 217 and subsequently outwardly through the hot air bars will result in the pressure actuated switch 237 being moved to a closed position. Now upon moving the switch 241 to a closed position the solenoid coil 245 is energized to provide a hold-in circuit across

terminals

246, 247 and also to energize the heater elements through terminals .248, 249. After the heater elements have been energized a sufficient period of time to bring the air temperature up to the desired temperature range, the temperature being indicated by thermometer 191, the drive mechanism of conveyor :12 is actuated so the conveyor will move a bag to have its leading edge 230a enter the throat 44. As the leading edge of the bag advances sufficiently to be intermediate the knife mounting members 109-112, the belts are held by said members in sufficiently tight abutting relationship so that the bag cannot move relative to the

inner runs

60b, 61b, 96a, 99a of the belts. As the bag is further advanced in the direction of arrow 275, first the leading vertical edge 230a engages the cutting edge of the knife 114 and then further advancement of the bag results in the portion 23% of the bag top above the cutting edge of the knife to be trimmed off. The trimmed portion 23% is moved at the same rate as the bag off which it is trimmed and subsequently advances to a position such as illustrated in FIGURE 2B wherein said trimmed portion is carried by runs 96b and 99b transversely outwardly to a position to fall off the support 40 and be deposited in an appropriate receptacle.

The trimmed bag then moves rearwardly past through the

cutouts

46 and 47 to subsequently have the leading edge thereof abut against the 'bag top opening bar (see FIGURES 5 and 6). As may be noted in these figures, the trimmed top edges of the bag are at an elevation whereby they engage the bar 142. The further advancement of the bag causes the top leading edge portion of the bag to be bent backwardly and this results in the top portions of the side walls spreading apart whereby one top sidewall portion overlies the generally horizontal portion of inner run 60b and the opposite side wall portion overlies the horizontal portion of inner run 61b, the interior surfaces of the thus bent over portions facing up. The radial distance from the bar 142 to the bottom angular portion of the brush is sufficiently small so that in conjunction with the rate of movement of the belts, the bent over bag top sidewall portions do not resume a vertical extending position prior to being engaged by the brush. The brush revolving in the direction 145 brushingly engages the interior surfaces of the folded down top side wall portions to clean any material from said side wall portion that would otherwise contaminate the seal subsequently formed.

After the inner surfaces of the top sidewall portions of the bag have been cleaned by the brush, they can again generally resume their vertical shape, the continued advancement of the bag bringing the leading edge intermediate the hot air bars 174 and 175. As may be noted from FIGURE 7, the outlets of the hot air bars each direct the exiting air generally horizontally toward the other bar at an elevation approximately the same or slightly lower than the maximum normal elevation of the trimmed bag top edges in a vertical upright condition. As a result the flow of air from the bars strikes the opposite sidewall portions of a bag to move them into an upright abutting relationship throughout the longitudinal length of the bag top prior to the time that the bag material is sufficiently heated to cause the bag material to flow, provided the sidewalls are not already in that position. As the bag top is further advanced between the hot air bars the bag material is sufliciently heated so it is momentarily melted to flow to form a bag top bead 250 such as illustrated in FIGURE 7. Thus, prior to heating the material sufliciently to melt it, the bag top sidewalls extend to an elevation such as shown in dotted lines between the arrows indicating the air flow from the hot air bars and upon being heated the bag top bead is formed as indicated in FIGURE 7. The air stream thereby serves two functions: (1) hold the edge portions to be sealed in a juxtaposed condition and (2) heat said edge portions to form a seal bead.

The air stream also serves a third function. That is by suitably adjusting valve 220, the air pressure of the air exiting from the hot air members can be adjustably controlled. By controlling the pressure exerted on the molten bead, the top sidewall beaded edge portions are forced together with suitable force to make a good seal.

Further advancement of the bag moves it out from between the hot air bars and subsequently it passes from between belts 61 and 62. During the last mentioned movement of the bag the bead cools sulficiently so that the bag may be handled without danger of rupturing the bead seal. Since the belt runs 60b, 61b are of relatively long length, belts have suflicient time to cool after exiting from beneath the hot air bars and before moving to the forward end of the machine. As a result there is no overheating of the belts 60 and 61. Also to be mentioned, if it is desired to move a substantially larger number of bags through the machine in a given period of time whereby the beads do not cool sufficiently prior to exiting from the machine, cooling mechanism (not shown) may be provided for blowing a stream of cold air onto the bag top beads to cool them more rapidly.

In the event air flow through

tubes

204 and 205 is interrupted, the switch 237 will open to stop the application of power across the heater elements. Also the application of power across said elements will be stopped by depressing reset switch 244 sufiiciently long to de-energize coil 245. This results in the hold-in circuit being broken and it will not be reestablished until switch 241 is again manually depressed.

As a further illustration of the invention but not as a limitation thereof, the following illustrative dimensions are given. In one machine the longitudinal length of the main support plate 29 is about 25 inches, the corresponding length of the support 40 is about 14 inches, the corresponding length of each hot air outlet 178 is about 8 inches and the height of each outlet is about 0.010 inch.

Although the machine has been described with both a trimmer subassembly and a cleaning subassembly, it is to be understood, for some fields of use a more inexpensive type machine is suitable. For example in certain packaging operations where a relatively dust free product is to be packaged a machine such as described heretofore without the bag top trimming, and bag top opening and cleaning assembly is suitable. In such cases a bag top seal bead is formed as illustrated in FIGURE where the seal bead is shown at 305, the portion of the bag above the seal being shown as 306. If the bag of FIGURE 10 were trimmed as described with reference to the use of the machine of FIGURES 1-9, portion 306 would have been trimmed off.

As many widely apparently different embodiments of this invention may be made without departing from the spirit and scope thereof, it is to be understood that we do not limit ourselves to the specific embodiments herein.

What we claim is:

1. A method for forming a bag top closure seal on a bag top of a heat sealable bag comprising supportingly conveying in a given horizontal direction a heat sealable bag at its sidewalls at an elevation below the top marginal edges of the bag, spreading the top marginal edge portions of the bag as it is being conveyed, cleaning the interior surface of the spread marginal edge portions, and after cleaning the spread marginal edge portions, directing streams of hot air toward one another in directions transverse to the movement of the bag to contact the bag top adjacent to its marginal edges to form a heat seal bead closure.

2. For use in conjunction with a conveyor for conveying a filled heat sealable bag in a longitudinal direction to form a top closure heat seal, a bag top sealing machine comprising a longitudinally extending frame above said conveyor, longitudinally elongated conveyor means mounted on said frame for supportingly holding bag top sidewall portions of said filled bag in abutting relationship as the bag is being rearwardly moved by said conveyor and engaging said bag below the top marginal edges thereof, means mounted on the frame for discharging hot air against opposite sidewall portions of the bag that extend above said conveyor means to form a heat seal bead that provides a bag top closure, means mounted on said frame forwardly of the hot air discharge means to trim off the portion of the bag top that extends more than a predetermined amount above said conveyor means, and means on the frame intermediate said trimmer means and the hot air discharge means for cleaning contaminating material from adjacent interior sidewall portions of the trimmedbag that extend above said convey-or means.

3. A method of forming a bag top closure seal on a bag top of a filled heat sealable bag comprising supportingly conveying a heat sealable bag in a given horizontal direction at its sidewalls while holding together portions of the sidewalls below the top marginal edges of the bag and above the contents of the bag, cleaning the interior surfaces of the sidewalls that extend above said sidewall portions as the bag is being supportingly conveyed, and forcing the cleaned bag top portions together and forming a bag top closure heat seal bead including directing streams of hot air toward one another in directions transverse to the movement of the bag with sufiicient force to hold the bag to-p sidewall portions in abutting relationship and momentarily melt said edge portions to form the heat seal head.

4. In a machine for forming a heat seal bead joining adjacent bag sidewalls having marginal edges and made of a heat sealable material, a frame, means on the frame for supportingly holding said sidewalls in abutting relationship at an elevation spaced from said marginal edges and conveying said sidewalls in a rearward direction, means mounted on the frame for trimming off a portion of said sidewalls that extends more than a predetermined amount away from said conveyor means toward said marginal edges as the sidewalls are being conmelt said heat sealable material and form a heat seal bead.

joining said trimmed sidewlalls as they are being conveyed.

5. The structure of claim 2 further characterized in that said cleaning means includes means for spreading said adjacent sidewall portions apart, a brush rotatably mounted rearwardly adjacent said spreading means to have the bristles thereof brushingly engage the interior sidewall portions and means on the'frame for driving said brush.

6. In a machine for forming a bag top heat seal bead on a filled bag, a frame, means on the frame for conveying a heat sealable bag in a rearward direction and supportingly holding opposite bag top sidewalls in abutting relationship at an elevation below the top marginal edges of the bag, means for cleaning contaminating material from the interior surfaces of bag top sidewalls that extend above said conveying means, and means on the frame rearwardly of the cleaning means for forming a bag top heat seal bead closure along the cleaned portions of the bag top.

7. The structure of claim 6 further characterized in that the last mentioned means includes hot air means for discharging hot air against bag top sidewall portions to heat the bag top sufiiciently to form said heat seal bead and means for supplying hot air to said hot air means.

8. A bag top closure forming machine to form a bag top heat sea-l bead on a filled bag made of heat sealable material as it is being supportingly conveyed, said machine comprising a longitudinally extending frame, a pair of conveyor belts on said frame to extend generally the longitudinal length thereof, said belts each having inner runs, means for mounting said conveyor belts with said inner r-uns sufficiently closely adjacent one another to supportingly hold the bag top sidewalls against movement relative to the belts and to engage said sidewalls at an elevation above the contents in said bag and below the top marginal edges of said bag, knife means mounted on the forward end of the frame to trim off a portion of the top of the bag extending above said inner runs as the bag is being conveyed, means on the frame at an elevation above the knife means to cooperate with the inner runs to conveyingly hold the bag top as it is being trimmed, said belt mounting means including means for driving said belts to have the inner runs move in the same direction at the same rate as said conveyor and means driven by the belts for driving bag top conveying holding means, means mounted on the frame rearwardly of the trimming means for cleaning the top interior surface portions of the trimmed bag top that extend above said belts, and means mounted on the frame rearwardly of the bag top cleaning means for forcing the cleaned bag top sidewall portions into abutting engagement and thence form a bag top closure heat seal bead as the bag is being conveyed.

9. For forming a bag top closure heat seal head on a filled bag as it is being conveyed in a rearward direction, a heat seal machine comprising an elongated longitudinally extending frame, conveyor means mounted on the frame for conveyingly holding sidewall portions of a filled bag together at an elevation below the top marginal edges thereof and above the contents in the bag, means mounted on the frame for spreading the top sidewall portions of the bag extending above said conveyor means and cleaning the interior surfaces of the spread apart bag top portions, and means mounted on the frame rearwardly of the bag top cleaning means for forcing the bag top spread apa-rt portions into abutting relationship and forming a top closure heat seal bead while the bag top portions are in abutting relationship.

10. The structure of claim 9 further characterized in that the last mentioned means comprises a longitudinally elongated hot air discharge member on either tnansverse 15 side of the normal path of movement of the bag top through said machine to direct a stream of hot air of a temperature to momentarily melt the bag top material toward the other hot air member and at an elevation to strike the bag top, and means for supplying hot aid of said temperature to said hot air members.

11. The method of claim 3 further characterized in that it includes the step of trimming the bag top in advance of the cleaning step and While the bag top is being supportingly conveyed.

References Cited by the Examiner UNITED STATES PATENTS Smith 219364 Haslacher.

Piazze 53-373 X Kleist 219-305 X Phillips et a1 53373 X FRANK E. BAILEY, Primary Examiner. 10 P. H. POHL, Assistant Examiner.