US2982334A

US2982334A - Longitudinal seam sealer

Info

Publication number: US2982334A
Authority: US
Inventors: Francis H Cooper; Gilbert W Tew
Original assignee: Sperry Rand Corp
Current assignee: Sperry Corp
Priority date: 1959-04-24
Filing date: 1959-04-24
Publication date: 1961-05-02
Anticipated expiration: 1978-05-02

Description

May 2, 1961 F. H. COOPER 15T/u. 2,982,334

VLONGITUDIML sEAM SEALER 3 Sheets-Sheet 2 IN1/EN TQRS 01961' W Tew f1 TT N E YS Filed April 24, 1959 May 2, 1961 F. H. COOPER ET AL LONGITUDINAL SEAM sEALER 5 Sheets-Sheet 5 Filed April 24, 1959 INVENTORS1 finnois' E bayer BYZZKZ W Tel/f A TTNEYS United States Pate LONGITUDINAL SEAM SEALER Francis H. Cooper and Gilbert W. Tew, Durham,vN.C., assignors to Sperry Rand Corporation, Wilmington, Dei., a corporation of Delaware Filed Apr. 24, 1959, Ser. No. 803,7 58

18 Claims. (Cl. 154-42) This invention relates to apparatus for sealing the longitudinal edges of material folded over into the form of a generally cylindrical tube, and particularly to apparatus for sealing successive lengths of the tube as it is formed in a package forming and iillin-g machine.

In general the apparatus is intended to be used with a bag forming and iilling machine wherein a continuous web of sheet material is drawn through a tube former and guided thereby, without internal mandrels or supports, into the form of a generally cylindrical ytube with the longitudinal edges of the` sheet Vmaterial overlapping along one side of the tube to'form a longitudinal seal.

The machine effects periodic drawing of the material through the tube former at intervalsv between which the tube is stationary. While the tube is stationary the ap-k paratus of the present invention functions to seal the overlapping edges of the material to form a longitudinal seal in the tube.

` Av relatively light paramagnetic bar is mounted tol extend into the tube-forming device" to` lie inside the tube directly inwardly of the overlappedredgres of lthesheet material. The bar is mounted at its outer end only, its

inner end (inside the tube) being unsecured. On-the outside of the tube a sealing head isjmounted and provided with an elongated edge portion arranged directly opposite the back-up bar with the overlapped edges of the tube-forming material therebetween. The` sealing head is provided with means for magnetizingV the same whereby it attracts the back-up bar..` to itself 'and thereby applies pressure to the overlapped` tube-forming material to eect sealing thereof. It is contemplatedthat the tube-forming material be a heat scalable type of material and the sealing head is further heated to a temperature sufficient to veffect .a heat seal under pressure. The sealing headtisrmaintained magnetized to apply 'pressure to theseam while the tube is` stationary.. When the tube-forming machine cycles'to draw `another length of material through'the tube former, thesealing head' is fdemagnetized to release the back-up bar and thusfree the webof material'for l movement withmitinterference fronior substantial contact-with the sealing means.-

The sealing head is held in fixed position relative tothe machine, the back-up bar being resilient and normally- 1 y Patented `May 2,v 1961 icc uniform pressure is applied throughout a substantial length of seam during the sealing cycle.

A further object of the invention is to provide a longitudinal seam sealer wherein the pressure on the seam is intermittently released without employing any moving parts. t Y

A still further object of the invention is to provide a seam sealer wherein the pressure applied to the seam is variable but accurately controllable without requiring the adjustment of any structural members.

An additional object is` to provide a seam sealer of the ltype set forth that is readily and easily adjustable for use with different sized tube formers. Y Y

Another object of the invention is to provide a longitudinal seam sealer of the type set forth that is relatively simple and economical in construction, yet highly Vefficient and completely reliable in operation.

Additional objects and advantages will become apparent to those skilled in the art as the description proceeds with reference to the accompanying drawings,

wherein: v

substantially along the line 4 4 of Fig. 2; v

Fig. 5 is'an enlarged vertical sectional View taken sub-l Y stantially lalong the line V5--5 of Fig. 2;

Fig. 6 is a fragmentary sectional view taken along the line 6-6 of Fig. 4;

'Figs.'7, 8, 9 and Figs. 10, 11, 12 illustrate vfurther modifications of sealing head adapted for use in the apparatus shown in Figs. 1 through 6.

t Referring iirst to Fig. 1,` the longitudinal seam sealer is shown` as part of a bagfforming, filling and sealing machine of thetype ldisclosed and claimed in `the copeuding 'application of Gilbert W.: YTew, Serial No.

811,867', filed May 8, 1959, now Patent VNo. 2,953,882.

Only so much of that machine is shown herein 'as will serve to show the enviroment for the `seamsealer yof the 'present invention. i. A 'Y Fig. 1 shows a fragmentaryportion 2' of the frame of the machine and shows arweb of material 4 fed fromV a suitable reel' (not shown) over-:anidler roll 6 `'and along a guiding collar 8 of a tube former. A one-way clutch v roll it) prevents retrograde movement of the web 4. The

' web tisV guided by the collar 8 tothe inner surface of `a 1 spaced from the elongated edgerportion ofthe sealing head tot thereby permitfreeimovement .ofthetube theref between. .Mere energization of electromagnet coilsvonA the l sealing' vThe Vapparatusofgthe present inventionfalso includes novel structural features Ywhichwill` be.` described in detail f lherein. Y

an. apparatusffn'f` forming alongitudinaliseal-in a tube of:

sheetimaterial by meansy presentingsubstantially no obstruction tothe interior offth tubeg l* f ftion of ahopper arrangedv to deliver ysuccessivecharges -of head eects ythe clamping previously de tubular` portion 12, of the tube former andV wherein the Vweb Vis caused `to assume"`a tubular vshape 4with its lon-j gitudinal edges overlapped at thefleft side ofthe tubey ,(as seenin Fig;A 1) and to extend' vdownwardly through the tube former `as aftube shown' inphantom lineat 14, The tube former shown guides the.. material 4 into tubular shape without;v employing internal'` rrlandrel's` or 'formera of any liindf,` Numerall indicates a fragmentary pormaterial to thein'terior of .thev tube former'to befdep'osited l in the tube-14 asit is frnmefd,v `As describedin th'e'c'o-v I pendingapplicationlidentified, above, a combine'dfhraw t 4fifinotlier object -kof'f tleitinventionis to@ provide a lor'r-V gitudinal. seamfsealerfinta tube-forming machine wherein bar and transverse sealingA mechanism periodically grips4 Fig. 4'is any enlarged horizontal sectional view taken Y 3 distance corresponding to the length of each successive bag formed thereby and severed from the tube. Therefore, the tube 14 is caused to move downwardly intermittently with spaced intervals during which it is stationary as shown. i

The apparatus of the present invention effects sealing of'the overlapped longitudinal edges 18 (see Fig. 3) during those periods when the tube is stationary.

Referring next to Fig. 5, the tube former having the collar 8 and tubular portion 12 is Vmounted in a bracket 20 on the frame of the machine. The tubular portion 12 comprises radially spaced overlapped forward edge portions 22 (see Fig. 2 also) arranged to guide opposite edges of the web 4 to the overlapping relationship shown in Fig. 3.V Y Y A further bracket 24 is mounted on the bracket 2t), by bolts 26 or the like, and is provided with a groove 28 in its upper edge slightly above and forwardly of the V-shaped front portion of the tube former. A relatively thin, narrow, and somewhat flexible back-up bar 30 of soft steel or other paramagnetic material is secured in the groove 28 by means of a screw 32 and is bent downwardly, at 34, to extend substantially vertically downwardly inside the tubular portion 12 in a position directly inwardly and closely adjacent theoverlapped edges 18 of the tube. As shown, the back-up bar 30Yis of reduced thickness adjacent its upper end whereby it is more flexible in that area than throughout the rest of its length. Asshown the back-up bar 30 is covered by a layer 36 of material that is non-adherent to the heat softened material of the web 4 so that the hot seam will not stick to the back-up bar. A suitable material for the coating 36 is Teilon or Teflon-impregnated Fiberglas.

The back-up bar 30 extends downwardly within the tube 14 a distance at least equal to the length of material drawn through the tube former at each cycle of operation.

A sealing assembly, indicated generally by numeral 38, includes a sealing head 40. The sealing head 40 comprises a pair of side plates 42 (see Fig. 3) converging inwardly at their forward edges and terminating in end faces 44 substantially coplanar but spaced apart and extending the full vertical length of thesealing head. The plates 42 are likewise of soft steel or iron or may be of any other suitable paramagnetic metal. A body 46 of nonmagnetic heat-conductive material is secured between the forward edges ofthe plates 42 by means of screws 48 or the like. The body 46 may be of aluminum, brass, or other metals or alloys having good heat-conductivity and yet being non-magnetic. The forward edge portion 50 of coils 56 are energized, magnetic force draws the backup bar 30 toward the sealing head, such movement being permitted by the flexibility of the back-up bar and particularly of the upper portion thereof previously described. The back-Yup bar is sufficiently rigid, however, so that it springs back away from the sealing head when the coils 56 are de-energized. Energization of the coils S6 is accomplished automatically in timed relation to operation of the bag-forming machine.

The sealing assembly 38 also includes mounting means for the sealing head 40. One of the plates 42 is provided with brackets 62 (see Fig. 2) secured to the outer face thereof. A support link 64 is pivotally connected to the brackets 62 by bolts 66, whereby the sealing head 40 is pivotally mounted on the support link 64 about an axis parallel to the longitudinal edge portion of the sealing head dened by the faces 44 and 50. The supporting link 64 is provided with laterally extending ears 68 (see also Figs. 4 and 5), through which adjusting screws 70'are threaded. The adjusting screws 70 bear -against the side plate 42 to which brackets 62 are attached and may be adjusted so as to pivotally adjust the sealing head 40 about the axis of screws 66. By means of lock nuts 72 the sealing head 40 is locked in the desired position of adjustment about the axis described.

The supporting link 64 is in turn pivotally mounted on a bracket 74 for pivotal movement about an axis defined by bolts 76. The supporting link 64 is formed with an upper horizontal `flange portion 77 having an arcuate slot 78 (Fig. 4) therein concentric to the axis defined by bolts 76. A lever 80 is pivoted to the bracket 74 on Vthe upper bolt 76 and is provided with a portion 81 ex- A tending radially to underlie the arcuate slot 78. Thus the body 46 is positioned between the faces 44 and is substantially coplanar therewtih and with those faces denes an elongated edge portion of the sealing head 40. A suitable heating element 52 is positioned within the body 46 and a thermostatic control element 54 is like- Wise positioned in the body 46.y

A plurality of wire coils 56 are arranged Yabout magnet cores 58 clamped between the plates 42 by bolts 60. The cores 58 are of paramagnetic material and are held in rrn contact with the plates 42 to. establish a good magnetic flux path. Thus, the plates 42 and cores 58 define an electromagnet structure having spaced pole faces 44 previously referred to. ,When the coils 56 are energized by Ydirect current one of the faces, 44Vwill become a north pole of theA magnet and the other face 44 becomes thefsouth pole. When so energized the poles 44jattract back-up bar'30 and draw the same towardythe sealinghead 40 with substantial force. Thus the overlapped edges 18 ofthe web4 are, tightly clamped together under 'pressure and heated by the body 46 sufciently to form a heat sealed joint or seam longitudinally of the tube '14. AAs previously described, .the backup bat 30 and the faces 44 and 50 are normally spaced apart suciently to permit the overlapped edges oftube 14 to moverrfreely therebetween. However, when :the

the lever 80 is pivotally adjustable relative to supporting link 64 but can be clamped thereto in a desired position of angular adjustment by means of clamping bolt 82 passing through the portion 81 and arcuate slot 78. The forward face of supporting link 64 is provided with a stop screw 84 and lock nut 86 in position to engage an extended portion 87 of lever 80 and this limits pivotal movement between link 64 and lever 80 in one direction. Thus, by loosening clamp screw 82 the sealing head 40 may. be readily and easily swung rearwardly (downwardly in Fig. 4) away from back-up bar 30, about the axis of screws 76 and without disturbing the posi tion of lever 80. Such movement of the sealing head isA sometimes desirable to render the back-up bar 30 temporarily accessible to an operator. When it is desired to return the'parts to their original position the sealing head 40 need only be swung forwardly until stop screw 84 engages the extended portion 87 of lever 80, which determines the correct position Vfor the sealing head. Thereupon the clamp screw 82 may be tightened to lock the head in the desired position.

The vbracket 74 is provided with a portion 88 on which a solenoid 90 is mounted. The solenoid 90 is provided with the 'usual movable armature 92-which is connected, through pivoted link 94 to the inner end of lever 80.

' The portion 88 of bracket 74 is further provided with a post 96 to which one end of a tension spring 98 is secured. The other end of spring 98 is attached vto lever 80, at 100. An arm 101 on portion 88 acts as a stop to limit outward movement of armature 92 when solenoid is de-energized.

- The machine on which the present apparatus is employed includes a housing portion 102 having an opening 104 (Fig. 2)in a wall thereof vand through which the portion 88 of bracket 74 extends. The plate portion 105 of bracket 74 bears against the outer face of the housing 102 and is' secured thereto by bolts 106 extending through the plate portion 105, through elongated slots 107 in thehousing 102 and threadedly engaging clamp vin a direction to move the sealing head towardand from the center of the tube'14. lIt is contemplated that tube formers of different sizes will 'be employed with the bag forming and filling machine and the present sealing apparatus can be employed to form the longitudinal seal in a bag of any diameter the` machine is capable of producing. The full line showing of Fig. 4 shows the bracket 74 in its foremost position for the sealing of a small tube 14. The dotted line showing of Fig. 4 shows the position the parts `would `assume when adapted to form a seal in a large tube v14'. It is to be noted that the adjustment for tubes of different sizes is accomplished simply by adjusting the bracket 74 along the slots 107. The screws 70, previously described, are employed to swing the sealing head 4u about the axis by bolts 66 to properly align the pole faces and the sealing face with the adjacent edge or face of back-up bar 30.

As previously described, heat and pressure are applied to the seam by energizing the coils 56 to thus magnetically dr-aw the back-up bar into pressure engagement with the seam. Upon de-energization of the coils 56 the back-up bar springs back to its released position. For extra fast release, a current of reversed polarity, smaller in magnitude than the original energizing current, is applied to the coils 56 to neutralize any residual magnetism in the sealer assembly or back-up bar.

When the machine is turned'on, preparatary to its cyclic operation, solenoid coil 90 isv energized and remains so until the machine is turned off. The energized solenoid 90 draws its armature 92 inwardly to the; extent of its movement, causing lever 80 to pivot about screws 76 and to thus swing the sealing head into its operative position shown. If it becomes necessary to gain access to the back-up bar 3l), the same may be accomplished without de-energizing the solenoid in the manner previously described. When the machine is shut off and `solenoid 9d `is de-energized, spring 98 effectsr clockwise swinging movement of the lever 8) and supportinglink 64,as -limited by arm 101, to thus retract the sealing head Y 40 Lfrom its operative position adjacent the back-up bar 30. `Even in such released position, however, the screw 82 'may be loosened to swing the sealing head farther Yawayfrom back-up bar 30, if desired or necessary.

Suitable wiring, indicated generally by numerals and 112 in Fig. 2, is provided to furnish electrical energy to the heating element 52, thermostatic control 54, and the electromagnet coils 56. It will be obvious to those skilled inthev `art that the pressure and temperature ap- Y plied to the seaml may be regulated atwill' without the necessity of making any mechanical adjustments, "fSuitable electrical controls (not shown) are contemplated 'for controlling the temperature maintained in the body 46 and the pressure applied to theseam may beV regulated by varying the current flowing in the coils `56. Suitable controls `for such currentrnay be provided by vthose skilled in the art and it is considered unnecessary, for an understanding of the invention, to show or describe suchcontrols.

described, comprises poleA faces 44 spaced apart laterally and extending the full Vlength of the elongated edge portion of the sealer-head.Y In 'this' yform of construction a back-up bar must be provided having a width at least about equal to the overall width of the sealing face of the head 4G. The faces 44 must have a substantial area a seam of substantial Iwidth Visvnecessarily formed by the The sealer head 40- shown inFig. 3 and heretofore 6 further embodiments of the sealing head adapted for forming narrow seams.

VReferring rst to Figs. 7, 8` and 9,- the coils 56 surround cores 58 clamped between side plates 120 in the same manner as described in connection with Fig. 3. The side plates 12d, however, are formed at their forward edge with spaced forwardly extending fingers 122. The fingers 122 on one of the plates alternatewith corresponding lfingers of the other plate and the ngers 122 are interleaved and arranged with' their end portions in the same vertical plane so as to define alternate spaced -but vertically aligned pole faces 124. As is obvious from Fig. 8, alternate pole ngers 122 are integral with one of the plates 120, whereas intermediate pole fingers are integral with the other plate 120. Thus, upon energization of the coils 56 the pole faces 124 are magnetized alternately as north and south poles, as indicated in the drawings. With this arrangement a much narrower back-up bar 30 may be provided and employed for forming narrower longitudinal seals. A body of heat-conductive

non-magnetic material

12,6 is cast about the fingers 122. to securely hold those lingers in the described relationship and to constitute a heat-supplying medium for the sealing operation. A suitable heating element 12S and a heat control unit are mounted in the body 126 for heating the same and controlling the temperature thereof.

A still further modification of sealing head is shown in VPigs. lO, ll and l2, wherein the pole* faces are defined by the ends of core bars 142 arranged in generally parallel relationship and embedded in a body 144 of cast heat-conductive but non-magnetic material. The core bars 142 are all arranged in the same vertical plane and are of generally L-shape so that their pole faces 140 are provided with only` a narrow gap 146 therebetween. The core bars 142 extend rearwardly beyond the cast body 144 and succeeding pairs thereof are bridged by core elements 148 fixed thereto by bolts 149. Each of ythe core elements 148 issurrounded` by a co-il 150 adapted to ybe energized to inagnetize the pole faces y14@ as north and south poles,V respectively. As sh0wn,4a plurality `of the pairs of `pole faces 140 are provided and define alternating north and south poles along the length of the sealing face of the head de-v scribed. `In this form `also a heating element 152 is mounted in the body 144, as is `a heat control device 154. The heating elements and the heat control devices re* ferred to herein in connection with the'different forms described may be any 'suitable unitsfor performing the described functionsV and arewell known to those'skilled intheart.` f f' As shown at- '16d in Figs.' l', 3 and 4, the sealingl head 40 is provided with a protective cover of srheetmetall or the like, arranged toV enclose all but the forward edge portion of the'head. While not shown in thedrawings, it is contemplated that the forms-shown in Figs. 7;'12 will also be providedwith such a cover `as the cover 16d:

The web 4 of bag-forming material maybe initially has been'found' thatlsucllv self-threading takes -placev witli-v` out interference `from the back-up bar" Sdwhich may remain mounted in place at all times.

if anV appreciable pressure is to be 'developed 'and thus While a limited number of the embodiments fof the in- `v'ention,k have beenshownandl described herein, it is to be lunderstood lthat the inventionernbraces other modifications falling withinthefscope of the appended claims;

l. In a machine for sealing overlapping--longitudinally i extending edges of al hollow tube of bag-forming rna-- t ,lterialz a frame; a thin back-up bar of paramagnetic material mounted on said frameto extend alor-ngV the path of' lmovement ofahollow tube-.closely'adjacent andl directly inwardly of the path of the overlapping `edges thereof, Y an assembly mounted on saidframe .and havingY arnagq netizable elongated edge portion extending along and closely adjacent said back-up bar outwardly of said path of overlapping edges, said elongated edge portion comprising spaced paramagnetic elements defining adjacent pole faces facing said back-up bar, whereby said paramagnetic elements may be selectively magnetized to draw said back-up bar and elongated edge portion toward each other to apply sealing pressure to said overlapped edges.

2. A machine as deiined in claim 1 wherein said backup bar and elongated edge portion are mounted on said frame to be normally spaced apart a distance slightly greater than the combined thickness of said overlapping edges but yieldably relatively movable toward each other by magnetic force acting therebetween.

3. A machine as defined in claim 2 wherein said backup bar is mounted solely from one end thereof by resilient means.

4. A machine as defined in claim 2 wherein said backup bar is of reduced transverse dimensions at one end thereof, said one end being secured to said frame for mounting said back-up `bar thereon, said one end serving to resiliently mount said bar for movement toward and from said assembly.

5. A machine as defined in claim 1 wherein said assembly includes heating means to heat said elongated edge portion for heat sealing said hollow tube.

6. A machine as defined in claim 1 wherein said elongated edge portion further includes a body of heat-conductive non-magnetic material extending the lengththereof and means for heating said body.

7. A machine as deiined in claim 1 wherein said assembly is movably mounted on said machine for movement toward and from said back-up bar, and selectively operable means fol holding said sealing assembly fixed in said position adjacent said -back-up bar.

8. In a machine for sealing overlapping longitudinally extending edges of a hollow tube of bag-forming material, the improvement comprising; a frame; a back-up bar of paramagnetic material mounted on said frame to extend along the path of movement of a hollow tube closely adjacent and directly inwardly of the path of the overlapping edges thereof, an assembly having an elongated magnetizable edge portion extending along and closely adjacent said back-up bar outwardly of'said path of the overlapping edges, means for magnetizing said edge portion, one end of said back-up bar extending longitudinally beyond said path and being iixed to said frame, said back-up bar being of relatively small transverse dimensions whereby the resilience thereof at said one end Vpermits flexing of said bar toward said sealing assembly.

9. A machine as dened in claim 8 wherein said backup bar is of reduced transverse dimensions adjacent said one end whereby it is most flexible adjacent said one end.

10. In a machine for sealing overlapping longitudinally extending edges' of a hollow tube of bag-forming material, the improvement comprising; a frame; a back-up bar of paramagnetic material mounted on said frame to extend along the path-of movement of a hollow tube closely adjacent and directly inwardly of the path of overlapping edges thereof, an assembly mounted on said frame and having a magnetizable elongated edge portion extending along and closely adjacent said back-up bar outwardly of said path of overlapping edges, a bracket on said machine, said assembly being pivotally mounted on said bracket for swinging movement toward and from said back-up bar, and selectively operable means for swinging said assembly toward said bar and holding the same in fixed position adjacent said bar.

1l. A machine as defined in claim l() wherein said bracket and selectively operable means are mounted on said machine for adjustment thereon along a path to move said assembly toward or from said back-up bar.

12. A machine as deiined in claim 10 wherein said selectively operable means includes a lever pivotally connected at one end thereof to said assembly, means for holding said lever in a selected position of pivotal adjustment on said assembly, and power means drivingly connected to the other end of said lever.

13. A machine as dened in claim 10 wherein said sealing assembly comprises a head and a support therefor, said support being pivotally mounted on said bracket, said head being mounted on said support for pivotal adjustment about an axis substantially parallel to said back-up bar.

14. In an apparatus for sealing overlapping layers of material to form a seam and wherein a paramagnetic Vback-up bar is positioned against said seam on one side of said material, the improvement comprising; a magnetic pressing head engageable with the other side of said seam to magnetically attract said back-up bar and thereby apply sealing pressure to said seam, said head having au elongated edge portion for engaging said seam, said edge portionl comprising spaced paramagnetic elements defining adjacent pole faces whereby adjacent ones of said elements may be magnetized to opposite polarity to exert maximum magnetic force on said back-up bar.

15. Apparatus as defined in claim 14 including a body of heat-conductive non-magnetic material defining at least a portion of said elongated edge portion, and means for heating said body wherebyrto heat seal said seam.

16. Apparatus as defined in claim 15 wherein said spaced paramagnetic elements are embedded in said body and extend to the surface thereof at said elongated edge portion.

17. Apparatus as delined in claim 14 wherein said spaced elements comprise the parallel edges of plates extending along the sides of said elongated edge portion.

18. Apparatus as defined in claim 14 wherein said spaced elements comprise a plurality of spaced pole pieces aligned along said elongated edge portion.

References Cited in the le of this patent UNITED STATES PATENTS Leasure Aug. 18, 1959