US3678813A

US3678813A - Bag machine

Info

Publication number: US3678813A
Application number: US176898A
Authority: US
Inventors: Robert J Wech
Original assignee: Individual
Current assignee: Individual
Priority date: 1971-09-01
Filing date: 1971-09-01
Publication date: 1972-07-25
Anticipated expiration: 1989-07-25

Abstract

The bag machine of the present disclosure is of the type which can produce bags made of various thermoplastic sheet material and can be adapted to make side weld or bottom weld bags. The following description will, however, be confined to the production of side weld bags. A roll of plastic web is mounted on an unwind stand and traverses a folding board constraining the web to fold along its longitudinal median or along a line spaced from and parallel to the longitudinal median in the event it is desired to produce wicketed bags having a lip with a pair of holes in which is inserted a U-shape wire called a wicket. Downstream of the folding board a gusseter is provided to produce a fold which permits greater expansion at the bottom of the bag. The folded and gusseted web thence comes under the influence of a reciprocating transversely disposed seal and cutter bar which divides the web, at longitudinally spaced intervals, to produce individual bags. The bags are then transported to a table which is provided with devices for arranging the bags into a stack.

Description

[is] 3,678,813 July 25, 1972 United States Patent Wech [54] BAG MACHINE ABSTRACT [72] Inventor: Robert-J. Wech, Pinecrest Road, RR. 5, Green Bay, Wis. 54303 plastic sheet materiwe Mi t 0 t dd e m mn n w .m e b r e V e w 0 in w n .w t D.

& 1 o N production of side weld bags.

Related U.S. Application Data Division of Ser. No. 760,048, Sept. 16, i968.

d and A roll of plastic web is mounted on an unwind stan traverses a folding board constrainin g the web to fold along its Field ofSearclii............::::::::::::..........

II- C I n .l. .111] 2 8 555 [[i folding board a gusseter is provided to produce a fold which permits greater expansion at the bottom of the bag. The folded and gusseted web thence comes under the influence of :1

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INVENTOR. ROBERT .1 weca ATTORNEYS BACKGROUND OF THE INVENTION In order to attain a production rate of 200 or more quality thermoplastic bags per minute it is essential to design the bag making machine with features that provide: (a) positive control of the film during its unwinding from the parent roll; (b) maintenance of a fixed positional relationship between the parent roll supporting stand and the infeed frame of the baging machine; when desired, a gusseting mechanism which provides a minimum drag to the film while insuring a gusset of constant depth; (d) web draw rolls whose nip pressure is evenly distributed and has the ability to apply a differential nip pressure from one end of the rolls to the other; (e) mechanism which will release the nip pressure in the event film movement is stopped to prevent the creation of flat spots on the film; (f) a seal bar which will maintain a uniform evenly distributed temperature throughout its length and one that is shielded to prevent heat loss to the film; (g) a seal bar drive arranged for a manual or automatic lift when desired or when web feeding is interrupted for any reason; (h) mechanisms to vary the length of the bag being produced while the machine is operating to correct or change the size of the bags accurately under operating conditions with no down time and; (i) a bag transporting conveyor, which conventionally runs at higher speed than the film, including an easily adjustable positive control arrangement whereby adjustments can be made under operating conditions to insure that the trailing end of the bag is engaged by a conventional bag slow down mechanism to stack the bags so that their margins are in registration.

SUMMARY OF THE INVENTION The present application is concerned with the provision of a gusseting mechanism which makes a gusset of constant depth,

. is rapidly adjustable to change the depth of the gusset and is movable transversely in the event it is desired to change the path of the film relative to the longitudinal median of the bag machine. To achieve such flexibility it is preferable, if not essential, that the gusseter be mounted at a place where the speed of the web is substantially constant so as to obviate the problems of uneven gusset depth due to film bounce. To fulfill this condition the gusseter of the present invention is mounted between the folding board and the infeed frame of the bag machine. The construction of the gusseting attachment is designed so that an operator can rapidly and easily adjust the gusseter to produce gussets of a wide range of depth and it also has the ability to reduce, to an absolute minimum, drag imposed on the film thereby reducing the nip pressure of the web feeding rolls. The gusseter is also designed to facilitate threading of a new roll of film into the machine. This is desirably accomplished by moving the gusset forming wheel out of contract with the film.

BRIEF DESCRIPTION OF THE DRAWINGS FIGS. IA and IB, when viewed together along the break line R show the bag machine of the present invention in longitudinal section wherein the path of the web is shown by a broken line and the direction of web feed is indicated by arrows applied thereto.

FIG. 8 is a partial section, on enlarged scale, taken along the line 88 of FIG. 4.

DESCRIPTION OF THE PREFERRED EMBODIMENT General Arrangement With reference to FIGS. IA, IB, 2A and 2B it will be noted that the bag machine of the present invention is generally indicated by the numeral 20 and it comprises an unwind stand 22 (FIG. 2A) rotatably supporting core shafts 24 which in turn support film rolls 26. The web, designated by the letter W, unwound from the roll 26 is folded along a line parallel to its ends by a folding board or a V-board 28. When so called even edged bags are made the fold line is located at the longitudinal median of the web while the fold line for lipped bags is spaced from and parallel to the longitudinal median. FIG. 2A shows the V-board set up for producing lipped bags since the left hand margin of the web, identified by L. H., is laterally spaced from the right hand margin R. H. downstream from the V- board 28. The web then comes under the influence of a gusseting mechanism 30 which forms an inwardly directed fold on that portion of the web which defines the bottom of the completed bag. The fold is shown by a dotted line in FIG. 2A and is identified by numeral 32.

Referring to FIG. IA it will be seen that the gusseting mechanism 30 is mounted on support arms 34 pivotally connected to a transverse rod 36 mounted to and extending between laterally spaced infeed frame members 38. Rotatably supported on the transverse rod 36 is a roller 40 which directs the web between a first set of infeed rolls of 42 connected to conventional nip pressure regulating means 43. The web is thence trained about a plurality of idler rollers 44, mounted on dancer arms 46, and rollers 48 extending between and rotatably mounted on the infeed frame members 38. The length of web accumulated in the path defined by the rollers 44 and 48 serves to provide a temporary supply which automatically increases or decreases in response to transient values of web tension. This arrangement tends to produce a constant value of web tension.

The bag machine frame comprises a base plate 50 having mounted thereon transversely spaced upwardly projecting side frame members 52 located substantially at the midportion of the machine. At the discharge end, outfeed frame members 54 are also mounted on the base plate 50 and served to support bag discharge control devices explained in detail hereinafter.

Referring again to FIG. IA it will be observed that between the infeed frame members 38 and the mid-frame members 52 a horizontal accessory platform 56 is connected therebetween and it serves to support hole punching assemblies 58 mounted on a base plate 60. As shown in FIG. 2B the base plate 60 is mounted on a rectangular frame 62 and is transversely adjustable on this frame. It is held in a selected transverse position by a lock screw 64. Longitudinal adjustment of the rectangular frame 62 carrying the hole punch assemblies 58 is accomplished by racks 66 and pinions 68. As shown diagrammatically in FIG. 2B the racks 66 are fixed to the inner surfaces of the side rails 56 while the pinions 68 are keyed to a transversely extending shaft 70 rotatably mounted in the rectangular frame 62. On one end of the shaft 70 a knob 71 is keyed for rotating the shaft 70 and consequently adjusting the longitudinal position of the hole punching assemblies 58.

Downstream of the hole punching assemblies 58 an electronic web registration device 72 commonly referred to as a scanner, is likewise mounted for longitudinal and transverse adjustment. Longitudinal adjustment is accomplished by pinions 74 (FIG. IA) in mesh with the racks 66. The pinions 74 are mounted on a transverse shaft 76 rotatably carried in generally L-shaped in frames 78. On the upright legs of the L frames 78 a transverse bar 79 is secured. Slidably mounted on the bar 79 is the scanner 72 which can be locked in any transverse position by a lock screw 80. On the horizontal leg of the L frame 78 a transverse bar 82 is mounted and it will be observed, by inspection of FIG. 1A, that its upper surface is in substantially the same plane as the web line. In order to insure repeated response of the scanner the upper surface of the transverse bar 82 is white in color so as to provide good contrast for detection of the printed registration mark. As is conventional the scanner is electrically connected to the control circuit of the bag machine to deenergize the clutch and simultaneously energize the brake thereby arresting the movement of the web for a sufficient period of time to allow the transverse seal bar to operate and thereby make the side weld for two longitudinally adjacent bags. After the seal bar completes its function the control circuit is then conditioned to release the brake and engage the clutch commencing web movement.

As shown in FIG. 1B upstream of the scanner the web passes between intermittently operating draw rolls 84 associatedwith upper and lower sets of the

stripper fingers

86 and 88, respectively, detachably mounted on transverse bars 90 and 91. The draw rolls are connected, as hereinafter will be more particularly described, with means, generally indicated by the numeral 92, for controlling the nip pressure the draw rolls exert on the film and for removing the nip pressure when required, either selectively or automatically.

To resist the deflection of the draw rolls, particularly at their midportion and thereby insure an even value of nip pressure along the length of the draw rolls, a back-up roll 94, in rolling contact with the lower draw roll, is provided. The backup roll 94 is rotatably mounted in a yoke 96 having a link extension 98 which forms one link of a parallel linkage mechanism 100. The vertical position of the back-up roll 94 and accordingly the back-up force it will apply to the draw rolls 84 can be selected by adjusting a screw jack 102.

Immediately downstream of the draw rolls there is provided a vertically reciprocating sealing mechanism 104, cooperating with an intermittently rotating seal roll 106 for making the transverse seals in the folded web. These seals constitute the lateral margins of the bags. The seal mechanism is reciprocated by a pair of cams 108 (one of which is shown in FIG. 1B) keyed to a shaft 110.

After the web passes the seal mechanism individual bags are at that time produced and they are received by a continuously operating belt conveyor 112. The index conveyor comprises a series of transversely spaced and aligned upper and lower sets of

belts

114 and 116, respectively, moving in a direction indicated by the arrows in FIG. 18, Those reaches of the belts which are traveling from left to right, as viewed in FIG. 1B, are in contact for the purpose of gripping the bags discharged from the sealing mechanism and transporting them to a stacking table 118 provided with adjustable stop plates 120 for collecting the bags in a stack.

The upper belts 114 of the index conveyor 112 pass around an idler shaft 122 rotatably supported on linkages 124 mounting a cam follower roller 126 which is held in engagement with a cam 128 by a spring 130. As shown in FIG. 1B the cam 128 is mounted on a shaft 132 and during operation the linkages 124 are oscillated raising and lowering the idler shaft 122 which serves the purpose of accommodating any over travel of the bags as they issue from the sealing and cutting mechanism 104 and thus prevent wrinkling of the bag.

Before the bags are discharged to the stacking table 118 they come under the influence of conventional corrugating rollers 134 which serve to stiffen the bag in the direction of movement so as to prevent distortion thereof as it is ejected to the stacking table 118. Before being discharged to the stacking table the trailing end of the bag is momentarily gripped by a slow down mechanism 136 of known construction.

In order to synchronize the speed of the belt conveyor so that bags discharged therefrom are momentarily gripped at or adjacent theirtrailing edge, an electrically adjustable direct current drive arrangement 138 (FIG. 1B) is provided. The drive 138 includes a DC motor, belt and pulley, not shown, for driving a shaft 143. The shaft 143 has an adjustable pitch pulley 144 at its opposite end which drives a belt 145 trained about a pulley 146 mounted on a shaft 147. The shaft 147 provides power for the corrugating rollers 134. To drive the index conveyor 112, a belt and pulley drive train, not shown, transmits power from the shaft 143 to the upper index conveyor drive roller which is adjacent the lower set of corrugating rollers 134. For purposes of adjusting the pitch of the adjustable pulley 144, a tightener pulley 148 tensions the belt and is carried by a stub shaft 150 mounted on an adjustable arm I52.

Gusseting Mechanism The gusseting mechanism 30, generally referred to in the above described general arrangement, is shown in greater detail in FIGS. 3 through 8. Referring first to FIG. 3, which shows an enlarged perspective of this mechanism, it will be seen that the gusseting mechanism is supported on the arms 34 by

rails

184 and 186 rotatably carrying a shaft 188 having keyed thereon pinions I90 and 192. The pinions are in mesh with racks 194,196 fixed to the inner vertical surfaces of the support arms 34. The

pinions

190, 192 are held in place on the shaft 188 by collars 198. The shaft 188 has a threaded extension beyond the rail 186 and has threadedly mounted thereon a jam nut 200, serving to lock the shaft against rotation, and a hand wheel 202 secured to the shaft 188 for effecting rotation thereof to thereby cause longitudinal translation of the gusseter mechanism 30 whenever the shaft 188 is rotated.

Rigidly attached to the upper surface of the

rails

184 and 186 is a support plate 204 provided with a slot 206. The support plate 204 has attached thereto a mounting bracket generally indicated by the numeral 208 for rotatably supporting a gusseter wheel 210 which, when in its operative position is located between stationary

gusseter plates

212 and 214, the upper and lower plate respectively. These plates are rigidly fastened to a laterally adjustable support bar 216 overlying and spaced from a lower support bar 218 by a spacer block 220.

The gusseter mounting bracket 208 is shown in side elevation in FIG. 7 and reference to this Figure will show that the bracket comprises an elongate rectangular bar 222 secured to the support bar 218 by bolt 224 having slidably fitted thereon a bushing 226 which is received in the slot 206 and is dimensioned to provide a sliding fit. As will be evident by inspection of FIGS. 3 and 4 it will be seen that the bar 222 extends sub stantially normal to the support plate 204 and adjacent its out board end it is tapped to threadedly receive a pivot bolt 228 passing through a boss 230 of an arm 232 rotatably mounting the gusseter wheel 210 on a small flat head screw 234.

Also projecting from the boss 230 is a lug 236 carrying a pin 238 having a spring biased ball 240 mounted in a retaining sleeve 242. As shown in FIG. 4 the rectangular bar 222 has a spherically shaped depression 244 located to receive the spring biased ball 240 when the gusseting wheel 210 is moved to the phantom outlined position shown in FIG. 4. This holds the gusseting wheel in that position and-its main purpose is to facilitate threading of the film through the gusseter. Prior to repositioning the wheel for gusseting, hand folding of that portion of the film adjacent the

plates

212 and 214 can be done beforethe wheel 210 is located between the

gusseting plates

212 and 214.

The gusset forming members, that is the

plates

212, 214, and the gusseting wheel 210, are arranged so that they can be located transversely relative to the longitudinal median of the bag machine. Such an adjustment is required when it is desired to produce bags of different length. For example if the film roll on the unwind stand is 24 inches wide the maximum length of a non-gusseted bag would be half that length or 12 inches; while a gusseted bag made from the same film roll would be reduced in length by the amount used for the gusset. In the event film of greater width is used in order to produce gusseted bags of greater length it would be necessary to move the gusseting wheels 210 and the

gusseting plates

212 and 214 to the right, as viewed in FIG. 3. For this purpose a clamping arrangement 246 is provided. With particular reference to FIGS. 3 and 6 it will be observed that the clamp 246 comprises a generally U-shaped base member 248 rigidly attached to the support plate 204 by fasteners 250. The base member 248 is formed so that the support bar 218 slidably fits in the generally rectangular space defined by the base member 248 and the plate 204 (FIG. 6). Disposed above the base member 248 there is a clamping bar 252 having a clearance hole adjacent one end through which is disposed a bolt 254 threaded into the base member 248. On the other end of the bar another clearance hole is provided having disposed therein a stud 256 also threaded into the base member 248 and provided with a knob 257. At the intermediate portion of the clamping bar 252 a set screw 258 is threaded therein. bearing on the upper surface of the bar 216, and is in forceable contact therewith when the stud 256 is tightened. This, of course, locks the

bars

216 and 218 in place and accordingly maintains the lateral position of the gusseting wheel 210 and the

gusseting plates

212 and 214 since they are mounted, respectively, to the bar 218 and the bar 216. In view of the above it will be apparent that when it is desired to change the lateral position of the gusseting wheel 210 and the

plates

212 and 214 all that is necessary is to loosen the stud 256 sufiicient to remove the force supplied by the set screw 258 to the bar 216. The desired position of the gusseting mechanism can then be achieved manually by pushing or pulling the

interconnected bars

216 and 218.

In order to accommodate the gusseter mechanism 30 to the machining characteristics of the film and to prevent damage to the film in the event portions of the film exhibit more or less resistance to formation, the gusseter wheel 210 is held in its operative position between the

plates

212 and 214 by a spring 260. As shown on FIG. 7 one end of the spring 260 is attached to a hook 262 having a threaded stem threaded into the arm 232. The hook 262 is held against rotation by ajam nut 264. The other end of the spring 260 is attached to a bead-chain 266 which extends beyond a catch 268 mounted on a bracket 270. As will be observed by reference to FIG. 6 the catch 268 is formed with two upwardly extending fingers which fit between adjacent beads of the chain 266. On the remaining end of the chain 266 a ring 272 is secured which serves to facilitate grasping of the chain and consequent tensioning of the spring 260 to the degree required by the forming characteristics of the film. When a desired degree of tension is achieved, usually determined by observing film formation while the machine is running, the chain is inserted between the upwardly extending pins of the catch 268. Accordingly it will be seen that by utilizing the spring 260 for urging the gusseter wheel 210 between the

plates

212 and 214 the gusseter has the ability to give in the event increased resistance is encountered consequently preventing damage to the film.

Another and further novel feature of the gusseter mechanism pertains to the general configuration of the

gusseter plates

212 and 214. As will be observed these plates are generally rectangular in configuration and are made arcuate at the intersection of the margins. As is known by those skilled in the art, regardless of their design, gusseting attachments wear rather rapidly even though surface preparations such as Teflon are applied to those portions of the gusset forming members which come in contact with the film. While the gusseting mechanism of the present invention reduces the wear to an absolute minimum, particularly on the gusseting wheel 210 since it is mounted for rotation thereby obviating or minimizing relative velocity between the gusseting wheel 210 and the film, the

gusseting plates

212 and 214 do encounter an appreciable amount of friction and thus are subject to wear. As shown in FIG. 8 the film encountering edges of the

gusseting plates

212 and 214 are identified as 212a and 214a respectively. The

plates

212 and 214 are provided with an auxiliary set of mounting holes, collectively identified by the numeral 278 (see FIG. 4) which correspond to the spacing of the mounting holes containing the screws 280. When the

edges

212a and 214a are worn to the extent that the gusseting function is impaired the

plates

212 and 214 are removed and are repositioned on the support bar 216 locating edges 21212 and 214b to make contact with the film and thus cooperate with the gussetin wheel 210 to form gussets.

hile the above arrangement of reversing the plates to use opposed margins of the

plates

212 and 214 to extend their useful life, it is within the scope of this invention to form the plates so that all four edges may be used.

Although the best mode contemplated for carrying out the present invention has been herein shown and described, it will be apparent that modification and variation may be made without departing from what is regarded to be the subject matter of the invention as set forth in the appended claims.

1 claim:

1. An apparatus for making thin thermoplastic bags from an elongate folded web comprising means for supplying such web folded along a line intermediate its edges, means for accumulating a quantity of the folded web and for imposing a desired tension to the web, means for intermittently pulling the web from said accumulating means while causing the web to be withdrawn from said supply means at substantially a constant rate, means located between said web supply means and said accumulating means, for forming a gusset at the folded margin of the web.

2. The apparatus of claim 1 wherein said gusset forming means comprises cooperating gusset forming members mounted on a frame which is movable relative to the longitudinal median of bag making apparatus.

3. The apparatus according to claim 1 wherein said gusset forming means includes vertically spaced rigidly mounted stationary plates having located therebetween a rotatable wheel resiliently biased between said plates.

4. The apparatus according to claim 3 wherein said plates are provided with at least one set of additional mounting holes so that they may be repositioned on the support therefor to present unworn plate margins to engage the moving web.

5. The apparatus according to claim 3 further comprising means mounting said rotatable wheel for pivotal movement toward and away from said plates, and means for holding said wheel away from said plates to facilitate threading of a new roll web through said gusset forming means.

6. The apparatus according to claim 5 wherein said wheel mounting means is connected to a spring which is arranged to impart a selected preload to said wheel dictated by the depth of the gusset desired and the machinability of the web.