Machine for wrapping substantially parallelepiped box elements

Hide panel

Patent issued

01/12/1993

Inventor(s):	Gamberini, Antonio Boriani, Silvano
Assignee	G.D. Societa per Azioni (Bologna)
Application	No. 07/730,701 filed on 07/16/1991
Current US Class	53/234, 53/228
Field of search	53/228, 53/230, 53/231, 53/232, 53/234, 53/375.9, 53/387.4, 53/466, 53/586
International Classes:	B65B 1106, B65B 4908, B65B 5110
Examiners
Primary	Sipos John
Secondary	Johnson Linda B.
Attorney, agent or firm:	Cushman, Darby & Cushman
US patent references	3040488, 3150475, 4194340, 4711065, 5003755
Foreign patents	3599 A/90 (07/17/1990, IT), 524460 (07/31/1940, GB), 962991 (06/30/1964, GB), 1112352 (04/30/1968, GB), 1239108 (06/30/1971, GB), 2235913 (02/28/1991, GB)

A machine for wrapping substantially parallelepiped box elements, typicallypacks of cigarettes, comprises a push rod by which each box is directedagainst a respective wrapper of heat-sealable material, and directedtogether with the wrapper into a pocket, also folders by which the wrapperis closed into a tubular sheath around the box, and a heat-seal device bywhich the overlapping edges of the wrapper are secured to one another. Thefolding and heat-seal steps both take place while the box remainspositioned in the pocket, with the folders and heat-seal device operatingsequentially and in such a way that the overlapping extremities of thewrapper are secured before bring released by the folders, thereby ensuringthat the wrapper remains taut.
BACKGROUND OF THE INVENTION
The present invention relates to a machine for wrapping elements of boxlikeand substantially parallelepiped embodiment.
In particular, the present invention relates to a machine by whichsubstantially paralleleliped box elements are enveloped in wrappers ofheat-sealable material.
The prior art embraces numerous wrapping machines, and more especiallycellophane wrapping machines, by which substantially parallelepipedcommodities, notably packs of cigarettes, can be enveloped bothindividually and in groups. Such machines generally comprise means bywhich to feed and subsequently index the boxes or packs, also foldingmeans, and sealing means.
Each box element is urged by the feed means against a respective wrapper,which includes a sheet of the heat-sealable material supplied in adirection perpendicular to the feed direction, and directed ultimatelyinto a recess together with the wrapper.
The dimensions of the recess are substantially identical to those of thebox element, such that upon insertion, the wrapper is forced into a `U`shape around the element by the side walls of the recess, with twoextremities or flaps projecting.
The folding means, which include a moving folder and a fixed folder, serveto fashion each wrapper into a tubular sheath around the respective boxelement by engaging the two projecting flaps and flattening them intooverlapping contact against one side or face of the element.
Finally, the two overlapping flaps are secured one to the other by thesealing means and the tubular configuration is thus rendered stable.
In many machines, the recess include one of a plurality of radial pocketsprovided by a rotary wrapping head that is indexed about a horizontal axisthrough a number of work stations.
The moving folder effects a reciprocating movement, and serves to flattenthe lower of the projecting flaps against the rearwardmost face of the boxelement at a moment immediately following the entry of the element and thecorresponding wrapper into the pocket, and immediately prior to theindexing movement of the head.
The fixed folder is provided by the bottom edge of an external hood, orcasing, disposed coaxial with the wrapping head in such a way thatsubsequent rotation of the head has the effect of flattening the upperprojecting flap of material over the already folded lower flap and thuscompleting the operation whereby the wrapper is fashioned into a tubularsheath around the box element.
While it is true that high operating speeds are obtainable with a structureof the type outlined above, there are also certain drawbacks as regards acorrect and durable fold of the wrappers around the corresponding boxelements.
A correctly folded wrapper is of great importance nonetheless, and adetermining factor contributing to the ultimate appearance of the endproduct.
Accordingly, it is essential that the wrapper be properly taut when foldedaround the respective box element.
The drawbacks in question derive first and foremost from the fact that,even with the projecting flaps of the wrapper properly folded against therelative side or face of the box element, the requisite tubularconfiguration of the wrapper does not hold sufficiently stable throughuntil the subsequent heat-sealing operation which, as already suggested,occurs at a time and location posterior to those of the folding operation.
This problem is aggravated in the case of the expedient described above,whereby the box element and the ensheathing wrapper are held in place inthe respective pocket, during the rotation of the wrapping head, throughthe agency of an essentially cylindrical hood or casing. In the course ofsuch rotation, in effect, contact with the inner surface of the casing islimited to the longitudinal corner edges of the exposed face of the boxelement.
Besides being unable to guarantee that the correct tubular configuration ofthe wrapper is maintained, the contact in question is difficult to achieveand maintain for two contrasting reasons, namely: too hard a contact maywell result in a damaging compression of the longitudinal edges of therear face of the box element, as well as causing the lower flap, pinchedbetween the fixed casing and the indexing element, to slide away frombeneath the upper flap; by contrast, insufficient pressure in the contactbetween the casing and the element will result in the two flaps beingallowed an undue degree of freedom, such that the wrapping material canslacken and the requisite tautness be lost.
Moreover, the wrapper is embodied in an extremely thin and pliable materialthat readily accumulates an electrostatic charge, a characteristic whichcomplicates the operation of the moving folder, caused as it is to slidein close contact with the lower of the two projecting flaps to the end offlattening the material tightly against the box element. This same slidingaction has the effect of inducing an electrostatic charge in the flap,which consequently tends to cling and is drawn back by the folder on thereturn stroke.
The problem is compounded by the fact that these electrostatic chargesincrease proportionally with any increase in the velocity of the slidingcontact between folder and flap, that is to say with higher operatingspeeds of the wrapping machine.
As may readily be deduced, in effect, the moving folder tends to drag thelower flap such that it bunches beneath the upper flap, with theinevitable result that the requisite olean, flush overlapping contactcannot be obtained subsequently.
This bunching or creasing of the lower flap leads in turn to a furtherdrawback during the subsequent heat-sealing operation, namely: the factthat one of the two overlapping extremities of the wrapper may be creasedsignifies a reduction in the surface areas effectively in contact, hencean inevitable reduction in dependability of the heat-sealed joint.
SUMMARY OF THE INVENTION
Accordingly, the object of the present invention is one of structuring awrapping machine of the type in question in such a way that theheat-sealable sheets of wrapping material are folded correctly into atubular configuration about their respective box elements and held steadythereafter until the heat-sealing operation has been accomplished, thuseliminating the drawbacks mentioned above.
The stated object is fully realized, according to the present invention, ina machine for wrapping substantially parallelepiped boxlike elements thatcomprises feed means, by which the box elements are directed againstrespective wrappers fashioned from a heat-sealable material andtransferred as one with the wrappers into a recess proportioned toaccommodate the box elements and wrappers together, also folding means bywhich each wrapper is formed into a tubular sheath about the correspondingbox element, and sealing means by which the overlapping extremities of thewrapper are secured one to the other to render the tubular formationstable.
In the machine disclosed, the folding means and the sealing means operatetogether at a single work station of which the recess forms a part, andare designed to execute the respective folding and heat-sealing operationsin a succession of steps, effected substantially without pause, wherebythe overlapping extremities of the wrapper are engaged by the sealingmeans before being released by the folding means, such that the wrapper isheld taut over the relative box element until the overlapping surfaces ofthe wrapper have been heat-sealed one to the other.

What is claimed is:
1. A machine for convolutely wrapping a parallelepiped box-like elementhaving opposed first and second faces, opposed third and fourth faces andopposed fifth and sixth faces, with a sheet of flexible and heat sealablewrapping material about said first, third, second and fourth faces andheat sealing, corresponding overlapped regions of the resulting wrapper toone another against said second face to provide a wrapped element,comprising:
transversally spaced first and second wall means defining between them arecess sized to slidingly accommodate said element, with first faceleading, said second face trailing and a first respective thickness ofsaid sheet of wrapping material interposed between said third face andsaid first wall means and a second respective thickness of said sheet ofwrapping material interposed between said fourth face and said second wallmeans; said first and second wall means also defining between them apathway longitudinally extending parallel to said first and second wallmeans and along which said box-like element can be moved from an upstreamend towards a downstream end of said first and second wall means;
means for receiving a sheet of flexible, heat sealable wrapping materialathwart said recess at said upstream end of said first and second wallmeans;
means for supplying a parallelepiped box-like element into positionupstream of said sheet of wrapping material and in axial alignment withsaid recess, with said first face thereof leading;
reciprocating push rod means engageable with said second face of saidelement for stuffing said element into said sheet of wrapping materiallongitudinally along said pathway and thereby inserting said element, withsaid sheet of wrapping material wrapped about said third, first and fourthfaces thereof, into said recess, with two flaps of said sheet of wrappingmaterial trailing;
first and second stop means associated with said first and second wallmeans and being transversally movable between a first, projected positionin which they effectively obstruct said recess at a downstream location,and a second, withdrawn position in which they effectively permitlongitudinal passage therepast of said element wrapped by said wrapper;
said reciprocating push rod means when engaged with said second face ofsaid element being adapted to stuff said element, with said sheet ofwrapping material wrapped about said third, first and fourth faces thereofso far along said pathway that said first face of said element, with athickness of said sheet of wrapping material thereon, engages said firstand second stop means, thereby defining a wrapping and sealing location insaid recess for said element;
means defining a first slot through said first wall means at a locationwhich is longitudinally spaced upstream from said first stop means by anamount which is effectively equal to the comparable dimension of saidthird face of said element longitudinally of said pathway, plus twothicknesses of said sheet of wrapping material;
means defining a second slot through said second wall means at a locationwhich is longitudinally spaced upstream from said second stop means by anamount which is effectively equal to the comparable dimension of saidfourth face of said element longitudinally of said pathway, plus twothicknesses of said sheet of wrapping material;
a first folder disposed for movement transversally of said pathway at saidfirst slot, between a withdrawn position, in which said first folder islocated effectively outside said recess, and a second position in whichsaid first folder projects into said recess immediately upstream of saidelement having said two flaps trailing, so as to fold and hold a first oneof said flaps flatwise against said second face of said element;
a second folder disposed for movement transversally of said pathway at saidsecond slot, between a withdrawn position, in which said second folder islocated effectively outside said recess, and a second position in whichsaid second folder projects into said recess immediately upstream of saidelement having a second one of said two flaps trailing, so as to fold andhold said second flap flatwise against said second face of said element,with two corresponding regions of said first and second flaps disposed inoverlapping relation;
heat sealing means associated with one of said folders so as to beeffectively carried into and out of said recess thereby, and actuablewhile said first and second folders are in said second positions thereof,for heat sealing said corresponding regions of said first and second flapsto one another;
said first and second folders having respective foremost edges which firstenter said recess as said folders are moved from said first positionsthereof towards said second positions thereof, and respective leadingfaces extending from the respective said foremost edges and which facedownstream when said first and second folders are disposed in said secondpositions thereof; and
said leading faces of said folders angling towards upstream from therespective said foremost edges thereof so as to tend to localize to saidforemost edges contact of said folders with respective ones of said flapsas said folders are moved from said first positions thereof to said secondpositions thereof.
2. The wrapping and sealing machine of claim 9, wherein:
said heat sealing means is movably associated with said one of saidfolders, for movement generally longitudinally of said passageway betweenan upstream position spaced out of contact with said corresponding regionsof said first and second flaps, and a downstream position engaging aconvolutely outermost one of said corresponding regions.
3. The wrapping and sealing machine of claim 2, wherein:
said one of said folders has means defining an opening therethrough, facingdownstream with respect to said pathway when said one of said folders isdisposed in said second position thereof; said heat sealing means beingdisposed to move through said opening for reaching said downstreamposition thereof, and for retracting into said one of said folders to saidupstream position thereof.
4. The wrapping and sealing machine of claim 2, wherein:
said push rod means is sufficiently narrow transversally of said recessbetween said first and second wall means, as to permit said first andsecond folders to begin folding respective ones of said flaps against saidsecond face of said element, before withdrawing longitudinally upstream.
5. The wrapping and sealing machine of claim 2, wherein:
said first and second wall means are each coordinately divided into twoportions, namely an upstream portion and a downstream portionlongitudinally between said slots and said wrapping and sealing locationin said recess for said element; and
a structure carrying said downstream portion of said first and second wallmeans and being movable generally transversally relative to said upstreamportion of said first and second wall means, for carrying away saidwrapped element.
6. The wrapping and sealing machine of claim 2, further including:
means for extracting said wrapped element from said recess.

BRIEF DESCRIPTION OF THE DRAWINGS
The invention will now be described in detail, by way of example, with theaid of the accompanying drawings, in which:
FIGS. 1 and 2 are longitudinal sections through the feed station of amachine according to the present invention; and
FIG. 3 is an illustration, on smaller scale, of a wrapping head formingpart of the machine according to the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to the drawings, 1 denotes a machine, in its entirety, handlingsubstantially parallelepiped and boxlike elements 3 to be enveloped inwrappers of heat-sealable material, which comprises feed and transfermeans including a reciprocating push rod 2, also folding means 6 andsealing means 7, at least associated with a work station denoted 8. Thereciprocating push rod 2 is capable of movement through a rectilinearhorizontal trajectory between a retracted position and an extended feedposition. Unless otherwise stated during the course of the description,the expressions forward, back, front, and rear, etc., are referred to thefeed direction described by the push rod in reciprocating between theretracted and extended positions. Similarly, the general reference to abox element 3 in the context of the specification can indicate a singlepacket of cigarettes or a group of packets, or indeed any given commodityof parallelepiped shape, singly or collectively, such as might beenveloped in a sheet of heat-sealable wrapping material. The push rod 2reciprocates internally of a channel 20, through which the box elements 3are guided from an initial position between the rod 2 and the channel 20,having been directed into place substantially at the moment in which thepush rod 2 reassumes the retracted position, for example by means of anelevator 21. The channel 20 is embodied essentially as a pair ofhorizontal guide plates 22 rigidly associated with a supporting structure(not illustrated) that forms part of the wrapping machine 1.
Numerals 23 and 24 denote two vertical guides associated with thehorizontal plates 22 and providing a path down which to direct singlesheets of heat-sealable wrapping material. The sheets, or wrappers 4, aresupplied to the station from above by conventional means (not illustratedin the drawings,) and brought to rest in a precise position as will becomeclear in due course.
Numeral 5 denotes a recess positioned in alignment with the push rod 2, bywhich the single box elements 3 are accommodated together with theirwrappers 4. The movement of the push rod 2 toward the extended positionterminates at the moment when the box element 3, directed forward by therod, has entered the interior of the recess 5.
Broadly considered, the recess 5 is created by an inner wall 10 settransverse to the rectilinear trajectory of the box elements 3, and a pairof horizontal walls 11 which occupy the same planes as are occupied by thehorizontal plates 22, at least during the passage of the box element 3into the recess.
The recess 5 generally will be encompassed by a further pair of side walls,vertical and parallel, which are not illustrated. The dimensions of therecess 5 are substantially identical to those of the box element 3, whichthus entirely occupies the recess 5 substantially without protruding fromits confines. The transverse dimension of the wrapper 4 (+i.e. transverseto the direction through which the wrapper approaches the station 8,) isgreater than the corresponding dimension of the box element 3.Accordingly, the wrapper projects from each side or end of the box element3 and is flattened against the corresponding side or end faces by thevertical side walls as the box element enters the recess 5. Thelongitudinal dimension of the wrapper 4, and the position in which thewrapper is held prior to being invested by the leading face 3a of the boxelement 3, are such that the wrapper 4 is folded around the box elementinto a `U` configuration by engagement with the edges of the recess walls11, the two extremities of the `U` projecting rearward as flaps of whichthe upper is denoted 15 and the lower denoted 16.
The flaps 15 and 16 are flattened against the box element 3 by the foldingmeans 6, and bonded one to the other thereafter by the sealing means.According to the present invention, the folding means 6 and the sealingmeans 7 are both caused to operate as part of the work station 8 at whichthe box element 3 is received into the recess 5, being mutually associatedand activated in succession, the folding means first, and then the sealingmeans, substantially without any pause.
Moreover, the sealing means 7 are brought to bear on the flaps 15 and 16 ofthe wrapper 4 while these plays are still engaged by the folding means 6and held thus correctly tensioned.
With particular reference to the example of FIGS. 1 and 2, the foldingmeans 6 include a pair of substantially flat elements 13 and 14 positionedin vertical alignment on opposite sides of the guide channel 20 andtraversed toward or away from one another, by means not illustrated, in avertical plane normal to the direction of movement of the push rod 2.
The traversing plane of the flat elements 13 and 14 is separated from theinner wall 10 of the recess 5 by a distance which is substantially equalto the depth of the box element 3, i.e. the dimension as measured alongthe direction of movement of the push rod 2. The movement of the flatelements 13 and 14 is such that the sum of their strokes is greater thanthe distance by which they are separated when fully spread apart.Accordingly, the leading edges 13b and 14b of the two elements exhibitcomplementary profiles that allow them to overlap without mutual contact.
As is discernible from FIGS. 1 and 2, the flat folding elements 13 and 14are angled marginally from their traversing plane in order to reduce theamount of electrostatic charge generated in the wrapper 4. The bottom flatelement 14 exhibits a more robust structure than the top element 13, andcarries a two-arm lever 17 which is pivotably anchored to the sideopposite that which enters into contact with the wrapper 4. It is to thislever 17, and more exactly to the tip of one of the two arms adjacent tothe shaped leading edge 14a of the flat element 14, that the conventionalsealing means 7 are mounted.
The flat element 14 provides an opening 18 alongside the leading edge 14a,through which the sealing means 7 are able to pass and enter into contactwith the wrapper 4.
The remaining arm of the lever 17 articulates with a control rod 25 whichis set in motion axially (by means not illustrated) and serves to rotatethe lever 17 in opposite directions between two limit positions, wherebythe sealing means 7 are brought into direct contact with or distanced fromthe wrapper 4, respectively.
As illustrated in FIGS. 1 and 2, and as discernible clearly from FIG. 2,the face of the flat element 14 that engages in contact with the foldedwrapper 4 is disposed parallel with the inner wall 10 of the recess 5. Theface in question occupies an area surrounding the opening 18, for a reasonthat will become clear in due course.
Numerals 26 and 27 denote top and bottom openings located between the guideplates 22 and the side walls 11 of the recess 5, serving to allow thepassage of the flat elements 13 and 14. The dimension of the bottomopening 27 measured along the direction of movement of the push rod 2 isgreater than the corresponding dimension of the top opening 26, by reasonof the bulk of the bottom flat element 14 and the sealing means 7, whichnaturally must be greater than that of the top flat element 13 alone. Anyobstruction that might be caused by the bottom opening 27 to the progressof the box elements 3 is precluded by the incorporation of an appendage 28into the bottom element 14 at its leading edge 14b, embodied in such a wayas to occupy the same plane as the bottom guide plate 22 when the bottomflat element 14 is in the lowered position and thus substantially restorecontinuity between the guide plate 22 and the wall 11 of the recess.
In the embodiment illustrated, the inner wall 10 effectively includes twovertical stops 12, which are positioned on opposite sides of the recess 5,occupying a common plane parallel to the wall 10 and capable of movementtherein toward and away from one another, between a position drawntogether, in which an advancing box element 3 is intercepted, and aposition spread apart, in which an advancing box element 3 is notintercepted.
Operation of the wrapping machine 1 according to the invention will now bedescribed, starting from a situation in which the push rod 2 is retractedand the elevator 21 is in the process of introducing a box element 3 to beensheathed in a corresponding wrapper 4. At the moment when the elevator21 draws into alignment with the bottom guide plate 22, the elements 13and 14 of the folding means will be in the drawn apart position and thesealing means 7 will be in the at-rest position of FIG. 1. The push rod 2is now actuated and extends along the feed direction, entering intocontact with the rearwardmost face 3p of the box element 3. Theforwardmost face 3a thus invests the wrapper 4 which was previously fedinto position between the vertical guides 23 and 24, whereupon the boxelement 3 is carried fully forward into the recess 5, pinning the wrapper4 against the inner wall 10, i.e. against the movable stops 12, which arecurrently are drawn together and motionless in the intercepting position.
As the push rod 2 proceeds forward, the wrapper 4 is folded into a `U`shaped configuration around the box element 3 by the edges of thehorizontal walls 11, and tautened gradually as the result of friction withthe plates 22, with the appendage 28 and with the walls 11 themselves. Themoment that the push rod 2 has completed its forward stroke, the foldingmeans 6 begin drawing together, the top element 13 first and then thebottom element 14, entering into contact with the upper and lower flaps 15and 16, whereupon the push rod 2 commences its return to the retractedposition. Accordingly, the vertical space occupied by the push rod 2 isless than that occupied by the box element 3, as discernible in FIGS. 1and 2.
The upper flap 15 is folded against the relative face 3p of the box element3 by the corresponding flat element 13, which remains in contact with theflap 15 through a distance equal to approximately half the length by whichthe flap 15 projects from the box element 3. Thereafter, the lower flap 16is flattened by the remaining element 14 against the same face 3p of thebox element 3, overlapping the flap 15, which was folded previously. Thebottom element 14 passes almost entirely across the lower flap 16,extending to the point where the sealing means 7 are brought intoalignment with the area of overlap between the two flaps 15 and 16 of thewrapper 4. Once the bottom flat element 14 is fully forward with itsparallel face disposed entirely in contact with the lower flap 16, thecontrol rod 25 is actuated to direct the sealing means 7 onto theoverlapping flaps 15 and 16, firmly against the box element 3. The sealingmeans 7 are activated to secure the flaps 15 and 16 together, thenreturned to their normally retracted at-rest position. Thereafter, theflat elements 13 and 14 are drawn apart in readiness for a further foldingand heat-sealing operation.
It will be evident beyond doubt that the wrapper 4, and in particular theoverlapping flaps 15 and 16, have no opportunity of receding once folded,given that the folding and heat-sealing operations are substantiallysimultaneous. Once folded, moreover, the flaps 15 and 16 are heldpositively and without interruption against the corresponding face 3p ofthe box element 3 until after a heat-seal has been effected. Thus, thewrapper 4 is fashioned into a tubular sheath around the respective boxelement 3 and suitably tensioned, then heat-sealed while continuing to beheld taut by the selfsame folding and tensioning means. Notwithstandingthat there may be electrostatic charges induced in the flaps 15 and 16 bythe return movement of the flat elements 13 and 14, there can be noadverse effects, given that the flaps 15 and 6 have already been sealedbefore the elements 13 and 14 are withdrawn.
With each heat-seal operation completed, suitable transfer means areactivated to distance the box element 3, now partly enveloped by a wrapper4 folded into a tubular sheath and secured by an overlapping longitudinaljoint.
In the example of FIG. 3, the recess 5 appears as one of a plurality ofequispaced radial pockets 9 provided by a rotary wrapping head 19 which isarranged to be indexed about a horizontal axis. In this arrangement, theinner wall 10 may be fixed in relation to the head 19 and embodied with ahole providing passage to means of conventional embodiment (notillustrated) by which the box elements 3 are ejected from each pocket 9 inturn. The wrapping head 19 is described no further, being conventional inembodiment. The notion of embodying the inner wall 10 of the pocket 5 astwo movable stops 12 will be seen to offer significant advantages, giventhat the partly enveloped box elements 3 can be ejected by passing forwardwhen the stops 12 are spread apart. Thus, the pocket 5 becomes part of acontinuous channel incorporating means at a given location, in thisinstance the stops 12, by which the box elements 3 can be detainedtemporarily. The box elements 3 can be distanced by negative pressuremeans 29, for example, offered to the forwardmost face 3a of the wrappedelement 3 (as in FIG. 2).
The option also exists of displacing and distancing the box elements 3 withheat-sealed wrappers by causing successive elements with as yet unsealedwrappers to act as pushing means.
Both solutions enable a reduction in the duration of the folding andheat-sealing cycle, hence a higher operating speed of the wrapping machine1. Providing that the various steps of the cycle are appropriatelycalculated, in effect, the push rod 2 can commence its forward strokeagainst the box element 3 even as the flat elements 13 and 14 begindrawing apart upon completion of the heat-sealing operation. More exactly,as the push rod 2 moves forward with a further element 3 and the foldingmeans 13 and 14 recede, the movable stops 12 will spread, the last boxelement 3 to be ensheathed in its wrapper 4 is removed by the ejectionmeans 29, and immediately as the wrapped box element 3 has passed through,the movable stops 12 can draw together to reinstate the inner wall 10 inreadiness to intercept the next box element 3 together with the relativewrapper 4, duly folded into `U` shaped formation.