US2321647A - Apparatus for making containers - Google Patents

Description

June 15, 1943.

Filed Sept. 21, 1939 can't-Rm.

CABIN E 1' III/1 I 'IIIIII Patented June 15,1943

orric APPARATUS FOR MAKING CONTAINERS Frank 0. Brougham and Edmond E. Poulin, Springfield, Mam, assimorl to United States Envelope Company, Springfield,

poratlon of Maine Mass a cor- Applioation September 21, 1939, Serial No. 295,938 r,

3 Clad.

The present invention relates to an improved apparatus for producing containers such as bags or envelopes from thin, flexible, moisture-proof transparent material, having the characteristic,

of being rendered adhesive through the applica- According to the invention, material having the above mentioned characteristics is folded to form a web providing continuous overlying areas, which web is then heat sealed or welded and severed at predetermined intervals to'complete a container-upon each operation of the severing device. However, we have found that after welding, material such as Pliofilm remains in a soft and tacky state for a considerable period of time, and obviously, soft and tacky material is not easily or neatly out. For this reason, we have provided spaced welds with unsoftened and therefore non-tacky material between, where it is easily cut, leaving the preceding and succeeding containers firmly Welded on either side of the cut. The invention further contemplates automatic control of the feed to insure proper registration of a printed design without disturbing the timing of the welding and cutting operations.

The above and other advantageous features of the invention will hereinafter more fully appear with reference to the accompanying drawing, in which:

Fig. 1 is a view in side elevation illustrating the apparatus embodying the invention.

Fig. 2 is a plan View of the parts shown in Fig. i.

Fig. 3 is a fragmentary view in perspective of a portion of a web and associated apparatus.

Fig. 4 is a diagram of the electrical devices for automatically controlling registration of a printed web. a

Fig. 5 is a sectional view on an enlarged scale, illustrating a modified form of heat sealing and severing device.

Referring first to Fig. l, a supply of thin, flexible, transparent material having the characteristics of Pliofilm is indicated at i, in the form of a roll from which the material 2 is led upwardly around a guide roll 3 to a suitable former 4, which folds the material 2 into a continuous web 2a of double thickness. As will hereinafterappear, the width of the folded web determines the depth of the pockets in the bags or containers which are subsequently cut from the web, with the former 4 beingof any suitable type to produce a folded web of the desired width,

The folded web 20 passes from the former 1% between rotatably driven pull rolls 5, which feed the web continuously over a platen roll it coop= crating with a rotating heat sealing-element i. The element 7 provides a heated bar 6 having spaced longitudinal sealing projections 9 which are adapted to engage the web 20; as supported by the platen roll 6 to produce spaced welds ta extending transversely across the web, as indicated in Fig. 2, in dotted lines.

After being operated upon by the sealing bar 8, the folded web firmly sealed along the spaced transverse welds So, next passes over a second platen roll iii for operation upon by a rotatably driven knife H. The rate of feed of the folded web 2a by the pull rolls 5 and the timing of the sealing element '8 is such that the knife ii en= gages the web to sever the same just as a pair of welds 9a are symmetrically disposed with reference to a vertical plane passing through the rotational axes of the platen roll it ,and knife ii.

' Consequently, the cut made by the knife ii is exactly between the welds to, entirely outside of the tacky zones, as indicated at lid in Fig. 2, and acomplete envelope i2, closed along three sides by the web fold and two welds ta, is thus produced by each operation of the knife ii.

In normal operation of the machine, the feeding oi. the material is suiiiciently constant from one bag to the next that no diiiiculty exists in placing the out between two closely spaced welds. In running. printed webs, where a design D is repeated for each bag, a slight slipping or variation in the web repeated many times, causes the printed design to get out of register with the welding and cutting of the web into individual bags. Since eventually half of the design might be on one bag and half on the next, well known photo-electric means are employed to constantly supervise the relation of the printed design to the welding and cutting means.

To this end, there is included in the connection between-the driving motor i3 and the pull rolls 5 a differential driving device it, which ineludes an element l5 providing gear teeth a in mesh with a worm IS. The worm i 6 is in turn driven by an auxiliary motor ii, and when the motor I! is at rest, the friction of the worm gearing prevents the element it from turning, with .the result that the main driving motor it rotates the pull rolls 5 as through a direct driving conde ree? recting motor I! rotate the element IS in one direction or the other; by rotation of the worm IS, the pull rolls 5 will be advanced or retarded with respect to the sealing element I and knife ll, depending upon the direction of rotation of the element l5.

In order to insure that the folded web 26 with the spaced designs D thereon will always be properly positioned for operation upon by the knife H exactly between welds, the web is provided at intervals with suitable indicia l8, see Fig. 3, and suitable light-sensitive means are provided for producing electrical impulses in response to the passage of the indicia i8. As shown; the indicia I8 are in the form of spots spaced on the web at intervals corresponding exactly tothe distance between designs D, and in the following description it will be assumed for purposes of illustration that the spots N are sufiiciently opaque to prevent passage of light through the otherwise transparent material.

In Fig. 4, there is illustrated a source of light i9, and a photo-electric cell 20 is disposed on the opposite side of the web 2a from the light source 99, so that when movement of the web 2a brings a spot it under the light source i9, there occurs a variation in the conductivity of the cell 20, as compared to its conductivity when only the unmarked transparent web is passing between the light source and cell. Conductors 2| lead from the cell 23 to a control cabinet 22, containing apparatus responsive to variations in the conductivity of the cell 23, and since the present invention does not reside in the details of a photo-electric cell, or its known manner of operation for register control, as contemplated herein, the control cabinet 22 is shown only diagrammatically as being adapted to function substantially as shown and described in Weber Patent No. 1,961,538, dated June 5, 1934.

The correcting motor ii is of any suitable type and, as shown, is provided with separate series field windings 23 and 25, independent energizetion of which is adapted to cause the motor i! to rotate in opposite directions. Thus, energization of the motor i1 through one field winding 23, causes the motor to rotate in one direction to produce a retardation of the pull rolls 5 through operation of the difierential ll, while energization of the motor through the other field winding 33, causes the motor to operate in the opposite direction to produce an acceleration of the pull rolls 5.

The control apparatus also comprises a selector switch 25 driven in timed relation with the knife H, as shown in Fig. 4, and briefly-stated the functioning of the apparatus is as follows: Printed indicia i8 pass photo cell 20 to energize it and, if early, the impulse passes through one'side of the selector switch 25 to cause motor I! to momentarily retardthe web by means of differential i4 and pull rolls 5. If on time, impulse does not get through selector switch. If late, impulse goes through other circuit of selec-' tor switch to cause correcting motor to turn in the opposite direction to advance the web. The

amount of correction or displacement is predetermined by suitable adjustments in control cabinet 22 and may be or as much as $4,", de-

pending on the condition of the web, humidity and other factors influencing the running of the printed web.

With a 34 correction, we need have little concern, but when it is necessary to suddenly advance or retard the web by or even by Va". it will be seen that the accurate timing between the welding operation at I and 8 and the cuttinz operation at It and II will I be thrown out of register, with the result that the cut may come in the middle of a weld, or it may come entirely outside of the area bounded by the two welds, causing in the first case a faulty cut, and in the second case, one bag with two welds and another one with one side entirely unwelded.

In order to obviate this difllculty, we have located the photo electric cell 2. and its cooperating light source I8 and adjusted the selector switch so that the indicia spot l8 passes immediately after the cutting of one cut and before the welding of the next succeedingweld. By so doing,- we have caused the correcting impulse to come at a time when, although it may change the bag length, it will not interfere with the close timing between welding and cutting of any one seam. This relation is clearly shown in Fig. 3, wherein the indicia I8 is shown as passing over the cell 23 after the knife H has operated.

Although with existing photo-electric register controllers now on the market, this is the simplest method of achieving our result, we do not wish to limit ourselves to this method of timing the correcting operation, as it would not be difficult to time the correcting operation independently of the occurrence of the correcting impulse. For instance, by a condenser that would be charged at the time of the impulse and connected to a vacuum tube circuit by means of a rotary switch, in time with the machine, to cause the correcting operation at any desired time. Referring now to Fig. 5, there is shown, on an enlarged scale, amodified form of heat sealing and web-severing device incorporated in a single able on the head in any suitable manner, as by means of bolts 29 passing through elongated slots 30 in the arms 28a, and threaded into the head 27. Loosening of the bolts 29 will permit movement of the holder 28 on the head, and in order to obtain small adjustments of the holder, screws 3| are provided, threaded through lugs 32 so as to abut the upper ends of.the arms 28a.

The holder 28 carries a pair of sealing elements 33 extending downwardly toward the surface of the platen anvil 26, and a suitable electric heating coil 34 surrounds the elements 33 within the head 28. The head 28 with the elements 33, can be adjusted on the head 21 as described above, so as to cause the elements 33.

when heated, to engage the web 2a with just suificient pressure to form spaced parallel welds on the web similar to the welds 9a once for each web upon each downward movement of the head.

We claim:

1. A bag machine for making open-mouthed bags comprising means for rotatably mounting a supply roll of heat-fusible material so that the web of said heat-fusible material may be drawn through the machine, a pair of opposed draw rolls for drawing the web through the machine, a web forming element mounted between said draw rolls and the web supply roll arranged to engage said web along a line longitudinally thereof and intermediate its side edges and operable to cause the web to be folded lengthwise thereof into a doubled web with the free edges of the web residing adjacent one side of said doubled web and defining therebetween the open mouth of the bags, a sealing mechanism disposed at the other side of said draw rolls from said forming element and including relatively narrow closely spaced parallel heated portions arranged to engage periodically the doubled web transversely of said web to fuse together the fused zones therein.

'2. A machine fo making open-mouthed containers, comprising means for continuously feed-l, ing into the machine a length of heat-fusible material folded lengthwise into a doubled web bearing printed matter thereon at regular intervals, with free edges of the web lying closely adjacent each other and defining between them the open mouths of the containers to be made,

a sealing mechanism including relatively narrow, closely spaced, parallel heated portions arranged to periodically engage the doubled web transversely thereof to fuse together its overlying portions inpaired groups of relatively narrow closely spaced transverse welded zones, at regular intervals, cutting means engageable with said web after the operation of said heatsealing mechanism, and operable in timed relation with said sealing mechanism, to sever container sections from the web transversely thereof on lines intermediate each paired group of said spaced-welded zones, and register control apparatus comprising light-sensitive devices responsive to the movement of spaced indicia on said material to automatically maintain the movement of the web by said feeding means at such a rate that cthe printed matter on the web is always centered on a container, with said control apparatus adapted to function in an interval between the severing of one container and the welding of the next container.

3. A machine for making open-mouthed containers, comprising means for continuously feeding into the machine a length of heat-fusible material folded lengthwise int a doubled web. with free edges of the web lying closely adjacent each other and defining between them the open mouths of the containers to be made, a sealing mechanism including relatively narrow,

closely spaced, parallel heated portions ar-.

ranged to periodically engage the doubled web transversely thereof to fuse together its overlying portions in paired groups of relatively'narrow closely spaced transverse welded zones, at

regular'intervals, and cutting means comprising a blade located between said spaced parallel heated portions and operable to engage said web transversely, between each pair of welded zones,

' to sever container sections from the web.

FRANK O. BROUGHAM. EDMOND E. POULIN.

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