Web feeding means for container forming apparatus

April 28, 1953 s. r. howard 2,636,731

WEB FEEDING MEANS FOR CONTAINER FORMING APPARATUS

Filed March 30, 1948 4 Sheets-Sheet 1

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April 28, 1953

S. R. HOWARD

2,636,731

WEB FEEDING MEANS FOR CONTAINER FORMING APPARATUS

Filed March 30, 1948

Sheets-Sheet 2

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ATTORNEY

April 28, 1953 s. _R Howard 2,636,731

WEB FEEDING MEANS FOR CONTAINER FORMING APPARATUS

Filed March 30, 1948 4 _Sheets__{Sheet 3}

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ATTORNEY

April 28, 1953

S. R. HOWARD

Filed March 30, 1948 web FEEDING MEANS FOR CONTAINER FORMING APPARATUS

2,636,731

Sheets-Sheet 4

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188

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INVENTOR.

BY

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ATTORNEY

Patented Apr. 28, 1953

2,636,731

UNITED STATES PATENT OFFICE

2,636,731

WEB FEEDING MEANS FOR CONTAINER FORMING APPARATUS

Stanley R. Howard, Milton, Mass., assignor to Pneumatic Scale Corporation, Limited, Quincy, Mass., a corporation of Massachusetts

Application March 30, 1948, Serial No. 17,972

Claims.

This invention relates to container forming apparatus.

In general the object of the invention is to provide a novel and improved packaging machine wherein a printed web of flexible sheet material, such as heat sealable printed paper, is utilized to, produce successive filled and sealed containers in a rapid, efficient and commercially acceptable manner and wherein novel provision is made for controlling the feeding of the web to effect registration of the successive printed sections of the web with relation to the container forming mechanisms within tolerances permitted by the commercial acceptability of the packages produced. In its preferred embodiment the invention is embodied in a tea-bagging machine.

With this general object in view and such others as may hereinafter appear, the invention consists in the packaging apparatus and in the various structures, arrangements and combinations of parts hereinafter described and particularly defined in the claims at the end of this specification.

In the drawings illustrating the preferred embodiment of the invention, Fig. 1 is a side elevation of a tea bagging machine embodying the present invention; Fig. 2 is a front elevation of the lower portion of the machine shown in Fig. 1 and illustrating the web advancing grippers; Fig. 3 is a plan view of the web advancing grippers shown in Fig. 2; Fig. 4 is an enlarged detail view in side elevation of web retracting mechanism and control means therefor; Fig. 5 is a detail view in cross section taken on the line 5—5 of Fig. 1; Fig. 6 is a front elevation of a completed tea bag and adjacent sections indicating the length of the normal net advance, and the advance with a corrective stroke, relative to the predetermined length of a bag section or distance between the printed indicia on the web; and Fig. 7 is an electrical wiring diagram for the control mechanism.

Referring now to the drawings, the present invention is illustrated as embodied in a commercial machine for making individual filled and sealed containers such as tea bags, from an elongated web or strip of container forming material in accordance with the method disclosed in the United States patent to Patterson, No. 2,272,530, issued February 10, 1942, and, in general comprises an improvement in the apparatus disclosed in the United States patent to Patterson No. 2,385,229, issued September 18, 1945. As herein shown, such machines may be constructed in duplex form for simultaneously producing two strips of connected and filled bags and for severing the strips through sealed portions thereof to form individual packages.

(Cl. 271—2.6)

In the operation of such a machine, and as illustrated in Fig. 1, a web of heat-sealable paper 10 is withdrawn from a supply roll 12 thereof and advanced over container forming mechanism 16 5 which operates to fold the web longitudinally along a medial line to bring together the two half sections of the web preparatory to forming a strip of connected bag sections 18. The container forming material is drawn over the form10 ing mechanism 16 by vertically and horizontally reciprocable gripping and advancing mechanism 20 operative to nominally advance the strip substantially one bag length each cycle of operation and to present the strip in operative relation to ¹⁵ the sealing mechanism, indicated generally at 22, arranged to apply heat and pressure to seal the strip simultaneously along a transverse zone 24 and an adj acent longitudinal zone 2 6 during each sealing operation to form a series of connected ²⁰ bag sections closed on one side by the folded edge 28 and heat sealed along the remaining side and at the top and bottom.

The paper being unwound from the supply roll i 2 and advanced by the gripper mechanism 20 is ²⁰ arranged to pass over a take-up roll 59 mounted for axial movement in a bracket 65. and then over an idler roll 71. The movable take-up roll 59 is yieldingly urged outwardly in its supporting bracket 65 by springs 67 and is capable of inward 30 movement during the unwinding operation in order to maintain the web relatively taut and to take up any slack between the gripper mechanism and the supply roll. The supply roll 12 may be provided with suitable retarding means such 35 as a friction bearing, indicated at 51, for preventing inadvertent unwinding of the web material, and, the idler roll 71 may likewise be maintained under a slight friction.

Provision is also made for depositing successive 40 charges of the commodity into successive of the uppermost bag sections, as they are being formed, by feeding mechanism indicated generally at 30, the feeding mechanism operating in timed relation to the operation of the strip advancing and 45 heat sealing mechanisms 20, 22 respectively. In the operation of the machine, the open top of a bag section which has been provided with a charge of the commodity during one cycle of operation is closed during a succeeding cycle. 50 Thereupon, the strip is intermittently advanced to severing mechanism, indicated generally at 32, which operates to sever the strip through successive transverse sealed portions 24 to form individual filled and sealed bags.

The machine illustrated and described in the Patterson Patent No. 2,385,229, above referred to, was particularly designed for producing pa4 of the web at a point approximately halfway between two marks 44 when the web is at rest, as illustrated in Fig. 1. Thus, during intermittent advancement of the web the light beam may be intercepted by a mark at about the halfway point in its advance, as illustrated in Fig. 7. The detector unit herein illustrated is arranged to be excited to prevent a retractive stroke only when the light beam is intercepted by a mark during the “scanning” period, that is when the circuit is closed by the timing switch 48, and then only when the beam is cut off by the leading edge of a rapidly passing mark. If the mark does not appear during the scanning period, no correction is made, and, if the beam falls directly on the mark, and the mark then passes by so that the beam then falls on the relatively lighter background of the web during the scanning period no correction is made.

In the operation of the apparatus, assuming that the average bag length is approximately 2½ inches, for example, successive normal advancing and retracting movements are arranged to cause a net advance of the web about Λ of an inch less than the average bag length or about 2j5i inches net advance each cycle so as to effect a gradual and cumulative rising or “creeping up” of the marks 44 relative to the light beam until a point is reached where the beam is intercepted by a mark moving therepast. When this occurs the retracting mechanism is rendered inoperative so that the web is permitted to remain in its fully advanced position, the linear advance being slightly more, approximately of an inch more, than the predetermined length of a bag section, making the total stroke about 2H inches. Thus, it will be seen that the web advancing movement is either increased or decreased relative to the predetermined bag length within such tolerances as to effect substantial registration of successive bag sections with the container forming mechanisms.

Referring now to Figs. 1 and 2 for a more detailed description of the web advancing and retracting mechanisms, as therein shown, opposed grippers 48, 42 are arranged to be horizontally reciprocated in brackets 52, 54 respectively, the latter being adjustably clamped upon vertical rods 56, 58 supported for vertical reciprocation in suitable bearings provided in the machine frame. The rods, 56, 58 are arranged to be vertically reciprocated in timed relation to the operation of the bag forming mechanisms by a cam 69 mounted fast on the main cam shaft (60, and, as herein shown, provision is made for initially adjusting the effective stroke of the cam in order to enable adjustment of the linear advance of the grippers with relation to the spacing of the bag sections of the web. The rods 56, 58 are secured at their lower ends to a pair of yokeshaped tie pieces 62 only one of which is shown, the illustrated tie piece having a central slotted portion 64 for cooperation with a slide block 66 mounted on one end of an eccentric stud 68 car65 ried in a lever 70 fast on a rocker shaft 72, the eccentric stud being rotatably adjustable in the lever 70. The eccentric end of the stud 68 is provided with a roller 74 cooperating with the fixed cam path of the cam 66, as clearly shown 70 in Fig. 5.

With this construction it will be seen that by rotary adjustment of the eccentric stud 68 the effective length of the lever arm 70 may be varied, rotary adjustment in one direction operating to 75 increase the distance from the center of the

2,636,’ per tea bags made from a web of plain, unprinted heat sealable paper, and such machines are at the present time in extensive successful commercial use. However, when printed webs are used in a machine having a linear web advanc- 5 ing mechanism arranged to advance the web a length corresponding to a predetermined length of a bag section it is difficult to maintain correct registration of successive printed bag sections with the package forming instrumentalities since, 10 in practice, the sections may vary due to inaccuracies in printing, the effect of variations in. atmospheric conditions upon the web stretching of the web during withdrawal or possible slippage of the web. Thus, in the operation of such 15 prior machines on a printed web, any slight variations in the printed sections were cumulative so that eventually the web became out of register with the bag forming and severing mechanisms:- 20

In the illustrated embodiment of the invention, see Fig. 2, each web gripping and advancing mechanism 20 includes a pair of opposed cooperating grippers 40, 42 mounted to be horizontally reciprocated into and out of gripping en- 25 gagement with the web, and, to be vertically reciprocated to advance the web each cycle of operation. In practice, the linear stroke of the grippers-is initially adjusted so as to advance the web a distance slightly more than the predeter- 30 mined bag length or slightly more than the distance between successive substantially equally spaced registration marks 44 on the web, and normally immediately thereafter, provision is made for retracting the web a distance sufficient 35 so that the net advance of the web during each normal cycle of operation is slightly less than the predetermined bag length.

In the illustrated embodiment of the invention, provision is made for preventing retrac- 40 tion of the web by control mechanism responsive to the passage of the registration marks at a predetermined time in the web advancing cycle of operation thus permitting the web to remain in its initially advanced and overfed position 45 when a deviation of the registration mark from a predetermined position beyond permissible tolerances occurs thereby providing in effect a corrective stroke in the linear advance of the wet) during the same cycle of operation in which de- 50 tection of the need for correction by the control mechanism occurs.

In general, the control mechanism includes a photo-sensitive detector, indicated generally at 48, arranged to cooperate with the spaced regis- 55 tration marks 44 during the advancing cycle of operation; a timing switch 48 arranged to render the detector operative at a predetermined time in the web advancing cycle; web retracting means, indicated generally at 49; and a sole- 60 noid operated latch 50 arranged to render the web retracting means inoperative when actuated by the detector mechanism to permit an overfeed of the web. The gripper members are arranged to yieldingly engage the web during the advancing stroke with sufficient firmness to effect positive unwinding and advancement of the web, and, immediately after completing the web advancing stroke the gripper pressure may be released sufficiently to permit slippage of the web between the grippers during the web retracting operation.

In practice, the photo-sensitive detector 45 may be disposed relative to the web so that the light beam image is concentrated on the edge

2,636,731

...

rocker shaft 72 to the center of the roller 74 to thus decrease the effective stroke, and, rotary adjustment in the opposite direction operating to decrease the distance from the center of the rocker shaft to the center of the roller to thus increase the effective stroke. Thus, the linear movement of the gripper units may be initially adjusted so as to effect a linear advance of the web a distance slightly more than the predetermined spacing between successive markings 44. It will be understood that the gripper carrying brackets 52, 54 may be adjusted on their respective rods 5G, 58, to align the cooperating gripper units 40, 42 for cooperation with successive transverse sealed portions 24 of the web.

While the above description has been confined thus far to the operation of one pair of cooperating gripper units 40, 42 for advancing a web of container forming material into operative relation to the package forming instrumentalities, it will be understood that in the duplex machine herein illustrated, an identical and simultaneously operating pair of gripper units 4S0, 420 are carried by the brackets 52, 54 respectively, as illustrated in Fig. 3, the brackets being also adjustably supported upon similar vertical rods 5S0, 580 arranged to be vertically reciprocated by the cam 60 through similar connections including a lever arm fast on the rocker shaft 72 so that in operation each pair of grip- pers are simultaneously operated to cause the webs to be advanced into operative relation to their respective container forming, filling and severing mechanisms.

As illustrated in Figs. 2 and 3, each gripper unit 48, ¢2 and their corresponding units 400, 420 are supported for horizontal reciprocation upon individual rods 76 slidingly carried in the brackets 52, 54, each rod being provided with a coil spring 78 interposed between a portion of its supporting bracket and a collar 80 adjustably secured to the rod, the springs being arranged to urge the grippers inwardly into cooperating engagement with their opposing grippers and the container forming webs. The rods 76 of each unit are joined at their outer ends by a tie piece 82 and each tie piece carries a roller 84 arranged to cooperate with elongated cams 86 secured to vertical cam shafts 88, 90 respectively. Thus, in the operation of the machine, the gripper units 40, 400 and 42, 420 are horizontally reciprocated simultaneously into and from engagement with the vzebs, the springs 78 effecting a yielding engagement therewith and the cams 86 operating to positively separate the grippers. In the present embodiment of the invention, the cams 86 may be designed to relieve the grip on the web as soon as the grippers have completed their downward stroke to permit the web to be drawn back by the retracting mechanism, as indicated at 87 in Fig. 3, The vertical cam shafts 88, 90 are arranged to be rotated from the main cam shaft IGO by connections including bevel gears 92, 94 to the vertical shaft 88, bevel gears 96, 98 to a horizontal shaft 100, and a second set of bevel gears to the vertical shaft 90. One gripper member, 40, may be yieldingly mounted to provide a more accurate control of the gripper pressure, and, as herein shovzn, the gripper member 40 is provided with a pair of pins 101, 103 slidingly carried in a block 106 secured to the end of the rod 76. Springs 107 coiled about the pins and interposed between the gripper member and the block are arranged to yieldingly urge the gripper 40 toward its oppos ing gripper, each pin 101, 103 being provided with a nut 109 on its outer end for adjustably limiting the movement in such direction.

As above stated, the retracting mechanism indicated generally at 49 is arranged to normally retract the web slightly in order to effect a normal net advance of the web a distance slightly less than the predetermined bag length, and, as shown in Figs. 1 and 4, the retracting mechanism may comprise a pivotally mounted lever 192 arranged to cooperate with the idler roll 71 to grip the web between the end of the lever 102 and the idler roll and to effect reverse rotation of the roller 71 and retraction of the web when the lever is rocked in a clockwise direction viewing Fig. 4. As herein shown, the lever 102 may be mounted fast on a stud 104 pivotally carried by one arm 106 of a two-armed lever pivotally mounted on a rocker shaft 108, the second arm 110 being provided with a spring 112 arranged to yieldingly urge the retracting lever into cooperating engagement with the roller 71. The spring 112 is connected at its other end to a similar arm forming a part of the retracting mechanism for the second web of the duplex unit. A stop screw 114 engageable with the outer end of the arm 106 is arranged to adjustably limit the position of the lever 102 with relation to the roller 71 for most efficient results during the retracting operation.

As illustrated in Fig. 1, the lever 102 is arranged to be rocked to effect retraction of the web by a cam 118 fast on the horizontal cam shaft 100 and through connections including a cam roll 120 carried on the end of a vertical rod 122 mounted to be reciprocated in a bearing 124, the rod 122 being urged downwardly to hold the roller 120 against its cam by a spring 126 interposed between a portion of the bearing and a collar 116. The upper end of the rod 122 is provided with a tie piece 128 which carries two separate rods 125, 127 for cooperation with opposed retracting mechanisms of the duplex unit. Each rod 125, 127 is provided with a yieldable connection in which the rod is arranged to pass through a swivel 129 carried by an arm 131 also fast on the stud 104 the rod being provided with a collar 138 for engagement with the underside of the swivel to positively urge the retracting lever 162 into an inoperative position. A coil spring 132 interposed between the other side of the swivel and a nut and washer 134 at the outer end of the rod permits the lever 102 to be yieldingly rocked in a direction to effect the retracting movement. A third arm 137 fast on the stud 104 is arranged to cooperate with a stop screw 117 carried by the arm 106 for adjustably limiting the rocking or retracting movement of the lever 102, the yieldable connection permitting the rod 125 to slide through its swivel 129 when the arm 137 engages the stop. As previously described, the idler roll 71 may be held under a slight friction to prevent slippage.

From the description thus far it will be observed that the printed container forming web having spaced registration marks 44 thereon corresponding to the predetermined length of successive package sections may be intermittently advanced a distance slightly more than the distance between registration marks, initial adjustment of the linear feed being accomplished by rotation of the eccentric roller stud 68 in the lever arm 70 to provide an overfeed of the web, and, it will also be observed that the web may be normally retracted a short distance each cycle

2,636^731 of operation so as-to obtain a net advance of the web':. a distance slightly less than the·; predetermined package-length. In practice; the cam 118 may be. designed.to retain, the. lever 102. in its;retracting position, until; the, beginning.of, the. next cycle of operation, whereupon the lever. 102 may be.rocked- to its inoperative position at,the_;same time that the cam·. S2 effects downward,movement of: the: grippers during the web advancing stroke.

In order to. prevent, retraction, of. the; web. and thus permit the. web:to remain.in its initially, advanced and overfed position, the solenoid., operated, latch-50 is arranged to engage, the? extended end of the: arm-(:37 to. hold:the lever i.02 in its inoper.ative...position when the solenoid (33, is-energised, by·..the; detector unit: 46, and, as herein shown, the pivotally mounted latch 59 is provided' with: an arm 1.39 connected,by a.link 140:to the. armature 144 of the solenoid, the latch being normally, maintained in an-inoperative position by .a spring. (46. When the, retracting, member (02 is thus held¹ by the latch 50, the: operating, rod (25 is: permitted to slide-through its swivel (2.9. by virtue: of the yieldable connection. .

Referring now, particularly to Fig. 7, the dete.c- . tor: unit 46-is, arranged to-energise the solenoid (38 to prevent retraction of_; the web .when the .deteetpr, unit ,is. actuated by a registration mark .44 and, as herein shown, the, detector unit may- comprise any usual -or pref erred, photo-sensitive control, system-adapted, to. concentrate a beam of light-on the, web and- which is arranged, to be excited by a rapid'Phange,- in the reflective-characteristics; of the, surface upon, which the beam, is concentrated,such.as a rapid-change from a light to a dark surface of the moving web, the dark surface, being herein: illustrated as; comprising: the spaced: registration, marks 44 arranged to intercept the,beam.,.- When , the detector unit is thus excited.it is ,arranged, to- operate a relay (76 to. close a·.circuit- IJ8 to; the: solenoid (38, In.practice, the light beam, is continuously, operated but the unit .is operative to, actuate, the, relay 176 upon interception.,of.the:.beam;only during a predetermined time in the .cycle.:Of. operation, such;,predetermined time being herein deflned;as thescanning period, and,which,corresponds,to a time when the web has. been advanced substantially halfway in its movemenfcfr.om one position, of operation to another., .

As shown in Fig, 7 the scanning period is, controlled, by; the. timing, switch, 48 which includes a stationary contact (80 and a; movable contact. (82;. the;.-, movable contact, 1.82 being normally urged into, circuit closing-engage- . ment with, the stationary contact 1.80 by a leaf spring 184. The,contact,members 130, 182 are mounted upon an adjustable bracket; (86, and, the switch is operated to open, and close, a circuit. (88 to the detector unit. 46, in. timed relation to.-the operation of the machine.by, a cam 190 fast, on a vertical cam shaft 192-and, a cooperating- cam roller 194 carried by an; arm, (96 pivotally mounted at 198, The arm .196 is.provided with a-lateral extension .arranged .to engage,and rock .the con-, tact arm,.182.to. open the circuit .188, and a.spring 202 is provided .to; urge the. roller i 94. against its cam. The,’switch-.cam shaft 192 is arranged, to be rotated from the vertical, shaft 38 by. a gear train . including. a gear 204, idler_igear,2il6, and gear .2.08. fasten: the. switch,cam shaft,:1.9.2,,

Thus, the;circuit, (88. to,the detector;. unit,is closed..by, the.; cam (90 to provide a, scanning period during theadvancing stroke, at which-time . the.·, detectorsunit is rendered operative to energise the solenoid when the light beam is intercepted by a .registration .mark.. The, time .at which, the scanning period.startsrelative to. the moving, period, of the web, may be varied by rotary adjustment of ,thecontact,carrying bracket.186 mounted for rotary movement on the switch cam shaft (92 and provided,with an arcuate slotted portion 210 at its outer, end arranged- to receive a bolt 2(2 for fastening the bracket in its adjusted position.

,. It will be, understood that the characteristics of the preferred detector unit 46 are such that if the light .beam is directly, in alignment with a registration mark. 44 when the timing switch 48 is closed, thus indicating substantially registration of the package sections with.the container forming mechanisms, within permissible tolerances, the relay 176 will not be. actuated , and also if the light beam, is directed, on the; mark and then passes from-the . mark, to the relatively lighter surface of-the web material during the scanning period, also indicating, substantially uniform and commercially acceptable registration of the package sections, the relay will not be actuated to prevent retraction of the. web. The only time the detecting unit will respond to the passage of the moving web is when the light beam is first directed.onto the relatively light surface of the web material when the timing, switch is closed and is then rapidly intercepted by the passage of a relatively darker surface registration mark during the scanning period, such .position being indicated generally in Fig. 7 wherein the switch contacts (80, (82: are closed and the light beam is just about to be intercepted by a mark 44, indicating that'the package sections are lagging slightly behind proper registration, with the container forming and severing instrumentalities.

Upon interception of the light beam by the registration mark at such time, the relay 176 will : be actuated to close the circuit (78 to the solenoid 138 which is in turn energised to rock the latch member S0 into latching engagement with the extended end of the arm 137 thus locking the lever 102 in its inoperative position to prevent retraction of the web from its initially advanced and overfed position. Thereafter, in the operation of the machine, the uppermost package section is sealed and provided. with a charge of the commodity, the lowermost package section is severed from the web, and . the advancing , mechanism is operated to effect normal advancement and retraction of the web during the succeeding cycle unless the position of the web during such cycle is such, as to again require that the initial over ...advancement of the. web be maintained. It will thus be seen that.the retracting mechanism is rendered inoperative to retract the web and that in effect, corrects the position of the web during the same cycle of operation that a deviation is de.. tected to maintain the variations in the lengths of successive package sections within predetermined tolerances.

From, the description, thus far it will be seen that in the operation of the web advancing and retracting mechanism, the. web is normally advanced a-distance slightly less than the average spacing of successive printed package sections and that such predetermined advancement will cause the. registration marks to rise relative to ·, the light beam concentrated on the moving web . and that this action will be cumulative so that eventually the mark, will intercept the. light beam, as described, to render the retracting mechanism inoperative, and . permit the web to remain in. its. initially, advanced position of a

2,636,731 distance slightly more than the predetermined package length. As herein shown, similar control mechanism is provided for controlling each web of a duplex container forming machine, and includes a similar retracting unit 498, detecting unit 460, solenoid operated latch 5G8. and timing switch 480 so that in operation, although the web advancing mechanisms are concurrently operated through the same cam SO, yet each web may be individually controlled to selectively prevent retraction of the web as determined by its individual detecting unit.

Thus, the package forming webs are maintained in substantially registered relation within predetermined tolerances with respect to their respective package forming mechanisms comprising the package sealing mechanism 22, filling mechanism 30, and severing mechanism 32. These mechanisms may comprise the mechanisms illustrated and described in the Patterson Patent No. 2,385.229 above referred to, and to which reference may be had for a more complete description and mode of operation thereof. As herein shown, successive connected filled and sealed packages advanced into operative position to the severing mechanism 32 are cut off and received in suitable guides 390. 392 through which they are advanced bv intermittently operated pusher arms 394, 396 to be delivered from the machine.

From the above description it will be seen toat provision is made in the nre’ent anparatns for controlling the intermittent advance of a printed web of container forming material into operative position to the package forming and severing mechan’sms in accordance with substantially equally spaced printed indicia on the web definmg the length of individual package sections, the control means beins adapted to correct the linear advance of the web during, the same cycle in which a deviation from a nre-’eterm’ned snacing is detected, whereby to maintain the spacing corresponding substantially to successive printed package sections and. within commercial limits of deviation therefrom.

While the preferred embodiment of the invention has been herein illustrated and described it will be understood that the invention may be embodied in other forms within the scope of the following claims.