CA1200752A

CA1200752A - Power assisted rotatable film wrapping apparatus

Info

Publication number: CA1200752A
Application number: CA000435449A
Authority: CA
Inventors: Patrick R. Lancaster, Iii; William G. Lancaster
Original assignee: Individual
Current assignee: Individual
Priority date: 1982-08-27
Filing date: 1983-08-26
Publication date: 1986-02-18
Also published as: GB2126187A; US4524568A; GB8322948D0; DE3330489C2; DE3330489A1; GB2126187B

Abstract

ABSTRACT OF THE DISCLOSURE

A rotatable film wrapping apparatus for wrapping a load on a conveyor with an overwrap of stretched plastic film web, having a film web pre-stretching mechanism which is provided with a constant torque by a power assistance mechanism. The power assistance mechanism comprises a stationary ring adjacent a rotary ring on which the film roll and pre-stretch mechanism are mounted, and a friction roller on the rotary ring which contacts the stationary ring to transfer rotational energy to the pre-stretch device as the rotary ring rotates. The pre-strech mechanism comprises a downstream roller across which the film is drawn to the load at a speed which varies, and an upstream roller linked by gears to the downstream roller so that the upstream roller rotates, at a fixed fraction of the speed of the downstream roller to stretch film between the rollers. The energy of the friction roller is transferred through an adjustable constant torque device to the pre-stretch mechanism without controlling the speed of the pre-stretch mechanism, and since a constant torque is added to the pre-stretch mechanism, the the force on the film to the load can be substantially reduced while allowing the pre-stretch drive to speed up and slow down according to the film demand from corners or changing load size. This permits higher levels of stretch, faster payout speeds, and use of less uniform film than were thought possible previously. Relatively centered loads with minimum corner protrusion may be wrapped without the constant torque device by a proper selection of gears such that the downstream roller surface speed is driven slightly below the average relative surface speed of the load.

Description

t~75i~2 B~CKG~OUND VF IHE INVENTION

m e present invention generally relates to pRckaging and more particularly is directed to a rotating stretch wrapping apparatus for S mak mg unitary packages which hold a plurality of compGnents, each package ocntaining a lcad wrapped in a web of stretched film.
Case packing or bo ~ is a ocm~n way of shipping ~ltiple unit productsO Multiple unit products are generally stacked in a coIrugated hox or are wrapped with kraft paper with the ends of the kraft paper being glu0d or taped.
Scme manufac*urers use strapping of vertical steel or plastic bLnding to unitize the product. m e pm blems incurred in the use of strapping are the reguiremen~ of oostl~ oorner pro~ectors, danyer of bending or snapping and injuring the operator while applyL~g this high tension ~aterial to the loads, the ever present prcblem of settling due to ~oisbure wetting the cartons, and the sides bulging or normal vibration~s causing the straps to loosen and the lcad to come apaxt.
Glue is an alternati~e method used in some areast but cllstomer dissatisfaction with gl~ is high because r~val of glued cart~ns or 20 bags fr~n tl~e unit~zed lc~ds tends to tear outside layers of the cartons. Glue, alt~g}- an ~nex~ensive material, demands interleaving for product orientation ar~l thus requires more durable and expensive pac~lcaging material.
Because of the lack of alterna'cives of packaging, ~pe is 25 c~rrently being used ~ h~rizc~tally bind the top layer of the load.
However, tape is ex~ensive and allc~ws relatively free ~vement of all p~ su~w~.
Ar~other way of shiF~?ing products is ~y putting a sleeve or oovering of heat shrinkable materi 1 aroNnd the prodhlcts and shrinking 3~ the sleeve tD fonm a unitized package. The use of heat shrinkable film is described in U.S. Patent Nos. 3,793,798; 3,626,645; 3,590,549 and 3,514,920. A discussion of this art is set ~orth in U.S. Patent No.
3r867,806.
An eoonomi~l way of pac~aging pro~ucts is by wrapping the product load with a w~b of stretched plastic filmO

~ 1 ~ ~;-`i ()'75~

The elasticity of the stretched plastic film holds the products of the load under more tension thc~n either shrink wr~p or kraft wrap, particularly with products which settle when packaged. ~he eff~ctiveness of stretched plastic film in holdi~lg a load tcgether is a function of ~he contaLnment or stretch for oe keiny pl~oed on the load a~d the ultimate strength of the ~otal layered film wrap. These kwo functions are determined by the mcdulus or hardness of the fi~m after stretch has occurred and the ultimate strength of the fi~m af~er application. Containment ~orce is currently achieved by naxImizing elongation until just kelow a critical Foint where bre ~ g of the fi~m oc.curs.
The use of wrapping machinery to wrap s~ret~hed film ~round a load is ~ell known in the aLt. ~our types of stretch wrapping apparatus are oommonly used in the packaging industry and these types are generally ~escribed æ spil-al rotary machines, full web rotary machines, passthrough ~achLnes, and circular rotating machines~
A typical spiral machine is shLwn in U.S~ Patent ~o~ 3~863~425 in w~ich film is guided from a roll and wLapped arou~d a cylindrical load in a spiral oonfiguration. A carriage dxives the filn roll adjaoent the surfa oe of the load to deposit a spiral wrap around the load and retuxns in the opposite direction tD deposit another spiral overwrap aroNnd the load.
Spiral wrapping machines ~hich are curlY~ntly oommercially available are m2nufactured by Lantech, Inc. under Mcdel Nos. SVS-80, SV~M-80, STVS-80~ STV5M-80 and SAHS-~0.
A full web type of apparatus which wraps stret~h0d fi~m around a rctating load is disclosed in U.S. Patent No. 3,876,806 assigned to lantech, Inc. A similar ~ull web apparatus us ~ a tensioned cling film wrapped around a rotating load i5 shcwn by ~.S. Patent ~o. 3,986,611 while another apparatus using a tacky PVC fi~m is discl~sed in U.S
Patent No. 3,795,086.
Full web wrapping machines typical of those presen~ly commercially available æ e Model Nos. S-65, T-S5 and SAH-70 man~aciured by Lante~h~ Inc.
~nother ~ype of ~achine ~or wrapping a pallet load oo~mDnly called a passthrDugh ~achine is disclosed in U.S. Patent No. 3,596,434.
In ~his referenoe a pallet load is transported ~long a conveyor and the leading fa oe of the ExLllet load contacts a vertical CUrtalrl of film .~{.1~3 4~ ~
formEd by the s~aled leading edges of film webs dispensed by two rolls of film on opposite sides of the path of the pallet load. The pallet load oontinues to mcve along the conveyor, carrying with it ~he sealed fi~m curtain until the bw~ side faces of the pallet lçad as well as the front face are covered by film w~b. A p~ir of clamping jaws then close b~hind the pallet load, bringing the ~lo fihn web portions ~railing from the side faces of the pallet load into contact with one another ~ nd the pallet. The jaws then seal the film web portions tcge~her along two vertical l mes, and cut the web portions between those tw~ seals. Thus, the film web portions are connected to c wer the trailing face of the pallet load, and the film curtain across the conveyor is re-established to re~eive the next pallet load. The pallet load may subs~quently be exposed to heat in order to shrink ~he film web thus applying unitizing tension to the load, as i5 disclosed in U.S. Pat~nt No. 3,662,512.
Co~mercial passthrough machines are c~Irrently manufactured ky Weldotron, Arenco, and 5~T of France.
Varicus apparatus and processes have been developed to rotatably wrap stacked components to form a load.
Stationary loads which æ e Ibrought to a loading area an~l are wrapped by a rotating member which dis ~ ses stretched film arc~u~l a load are disclosed in U.S. Patent Nos. 4,079,565 and 4,109,445. U.S~
Patent No. 4,079,565 discloses a full web vertical wrap of the loa~
while U~S. Patent No. 4,109,445 discloses the hoxizontal spiral wrap of a load. U.S. P~tent ~ 4,050,220 discloses a wraFping devioe for multiple unit loads. Each load is oonvey~d bo a wrapping æea in which a load is supported on one or m~re stationary planar surfaces. The leadung ~dge of a roll of stretchable plast~c wraF~ing material is held adjaoent to the load, and the r~ll of material is rDtat~d about the load and ~he suppoxting planar surfaoes, WrappLng the load and the supp~rting surfa oe s toget~r. pl~stic wrapping material is stretche~ during the wrapping cperation so that the material is under tension when applied to the load. After the wrapping cycle is oomplete, the load is pushed past the ends of the supporting surfaces, and ~-~ wraFping ma$erLal which ccvered t~ suppor~ing surfaoes collapses against the suppor~e1 sides of the load. FuLther developments of this wrapping system are disclosed in ~.S. Patent Nos. 4,110,957 and 4,178,734.
U.S. Patent No. 603,585 discloses a spiral wrapping device for enclosing individual n~spapers ~n paper wrap for mailing purposes.

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~ch n~ is placç~d on a ~ylindrical o~re with a ci~nference appl~x~tely ~ice ~t of a newspaper, and each newsF~per advances c~ ong th~ length of the ct~re as the oore is rotat0d. ~qraE~irlg paper is ~l.i~3d to ~ core at an angl~ d the wraE~?~ paper be~een 3~ewsp~ers is se~ered as each n~wspaper reaches the erx~ of ~ ~linder and is p.la~ d C51 a flat hcrizon ~l surfa oe , th~re~y colla~sing the ~apping paper against ~he ~erside of the new ~ r prcviously press~d ~5. Patent No. 1,417,591 discloses a wrapp ~ machine for ~ al items sua~ as b~xes in which each su~h item is cvnveyed along th~ surface c~ a h~rizon~.31 sheet of wrapping material. '~e ed~es of wr~ g msteri~l on each side of an item are curled ~pwar~ meet one anothe~- atop ~ ibem ~o ke wrapped there~q~ f.o ~ a ~ube a~und the ~ ~ leading end of ~e ~ e is sealed and the trail~ng end of the b~be is severed and then sealed to enclose the item. Ano~her de~i oe which utilizes this system of wrapping is disclosed in UOS. Patent No.
3,473,2~8.
In U.S. Pat~nt No. 2,575,467, a wrapper of cylin~rical packages for material such as sausage is disclosed Ln which the package i~ rotat~d ~bout its cylindrical axis as wrapping tape is applied at an angle to orm a cylindrical wrap.
In U.S. Patent No. 2,863,270~ two cylindrical ikems of ~pproximately egual diameter ane abutted at their planar ends, and placed by hand in a cradle which exposes the oo~plete circumferenoe of the abutting ends. A roll of wrapping material is ~hen dri~en by a hand crank ~ nism to circulate around the circumferen oe of the abutting ends, applying wraFping material theneto. ~hen sealed together, the pair of cyli~drical itEms are remaved nom the cradle by hand.
A spiral wrapping machine for long bundles of items such as filaments is disclosed in U.S. Patent No. 3,000,167. As the bundle of filaments ~oves alcng its axis throu~h the wrapp ~ ~rea, a ring circulates abx~lt the bundle carrying a roll of wrapping material which is a~plied bo ~he hundle ~o form a spiral wrap pat~ern. Because the nonmal load of filaments or 5imi1ar items is m~ch longer than the wrapping area, i~ is not neces&~ry bo prcvide support for the b~ndle in the wrapping area, and there~ore no support stxucture i5 wrapped with the bundle.

,.... .. .

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All of these priox art apparatuses suffer from a severe limitati.on which relates to cost per unit load for film unitization.
Friction brake devices do not maLntain a c3n~istent stretch force on the fi.~r.l~ These brake devices are s~ject to vari2ticn ~le to their ph~sical oonstruction, se~siti~ity to spsed c ~ e caused ~y passage of l~d coxners, and the resultant sudden acceleration and deceleration of fi~m payoutO A t~pical 40" x 48" pallet load will incur a surface speed chz~ge of m~re than 40% with ach quarter tNrn. Moreover, it can be app~e~iated that these ~peed changes are substan~ially disoontinuwus as fi.lm disp~se~ by relative rotation of the film roll arcund the load is in~_-~epted by successi~e o~rners of the load. Higher rotation speed of 12-18 revolutions per minute prcdh oe additional resona~ing fo~ces ~hich ch~ ~e ~uring payout and the resu].tant weight decrease of the fi~m roll.
A~.~itional limitations on maxlmlm elongation are caused by film roll i~2rfections and g~uge variations which aocentuate the force var ~ tions de~r~rib~d above to produ oe fi~m ru ~ s. Even th3ugh all of the films pre~ously described carry manufactures specifie,d elongati~n capabilities above 30Q%, ~hese rates cannot be approached because of limitations imposed ky fricti~n-~ype brake devicesu Cçmmercial circular rotatiny wxaFping ~achines are presently nanufactured by Lantech~ Inc. under the trademark LaNRIN3eR, and are pr~vided with wrapping rLng Lnner diameters of 36 inc~es, 54 inches, 72 inches, and 84 inches. In dif~erentia~ing betw~ the v æ ious circular r~tating wra~pLng ~achines manufactured by Lantech, Inc., the manual n~del has the ~esignation SR; the ~ull web nDdels have the designations SVR and 5AVR; the multiple banding models have the designation SV~R and SAY~R; the sp ~ 1 mLdels have the designation SVSR and 5~VSR, and the conti~us wxap ox bundler m~dels have ~he model designations SVCR and SAVCR.
U~ted States Pate~t Nos. 4,302,920 and 4,317,322, assigned to Lantech, Inc., discloses a pre-s~retch fil~ elongation ~stem moun~ed adjacent a fi~m xoll and rDtated about a stationary load. lbe pre-stretch system ~hich is mDunted o~ the rotating ring includes an upstream roller and a downstream roller across which the film web successi~ely passes~ The two rollers are speed ocupled by gears, belts, or the like, which force a oonstant ratio of angular velocity ~etween the rDllers. Film is drawn fram the film roll and across each of the rollers by relative rD~ation oE the ring around the load. T~e fixed speed ratio be~een the upstream and dc~tream rollers, ~n w~ich the ~wnstream roller Ir~ves m~re ~c3cly than the u~?stream roller, causes substantial stretching bet:~een the rollers of the w~b. However, it can be a~reciat~3d that the e~tire fc~rce exerted be~een the rollers is due 5 to film being wrapped about the load. In this d~7ioe the s~ibstantial ch~nges Ln payout ~ ~d are tr~t~ed directl~ from the load back t~x~gh the web to the pre-stretch d~vioe, so tha~ the level of ~orce exer~ on the film betwee~ ~he downstr~am roller and the load remainc relati~ely cDnstan~.
SUMMARY OF THE INVENTION
~ , , In one aspect of the invention, the invention provides for applying stretchable plastic film to pallet loads using a pre-stretching mechanism which is responsive to the force exerted by the film web being drawn through the pre~stretching mechanism during rotation of a film roll about a load.
In another of its aspects, the invention also provides a pre-stretching mechanism having a constant torque charact-eristic~ Because a constant torque is added to the pre-stretching mechanism, the speed changes required for the corners are transmitted directly to the pre-stretch mechanism allowing substantial reduction in force on the film required to drive the pre-stretch mechanism, which permits higher levels of stretch, faster payout speeds, and use of less uniform film than were previously thought possible. The present invention reduces the likelihood of load collapse and improves the film tolerance of irregular loads as the force on the film web between the downstream roller and the load is less than in the prior art.
Although the invention is set forth in the claims, the invention itself and the method by which it is made and used may be better understood by referring to the following description taken in connection with the accompanying drawings forming a part hereof, in which like reference numerals refer to like parts throughout the several views and in whicho . i . ,. - - .. ~ . .

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DFSCRIPrION OF THE D~
EIGUgl: 1 discloses a perspeotive view of the inventio~ ~ly broken awa~ disclosing the irYv~ntive apparatus;
El(~ 2 di~closes an enlarged reversed side elevational view 5 of ~e i~ventian as sh~ Ln EIGU~E l;
El(~53 3 is an enlarg~l fron~ elevatior~al view of the in~en~:ion shown in FIaJlæ l;
~ IGURE 4 ~s a oontinuous spiral burx~ling sys~n with a s~nae of o~secutive padsages wra~ped b~ 'che ~entic~;
E'~ E S discloses a ~1 w~ >de of wral~ acoc~plished ~y the ~;r~tive ~paratus;
El~æ 6 di~closes a bandirig m~de of wra~ aoo~rg?lish~ y the ~ renti~re a ~ aratus;
EIGUE~E 7 discloses a spiral ~de of ~ap acccnplish~ y the ~ entive aE~?aratus;
FIGURE 8 discloses a side elevational view o~ a web severing ism used in the invention;
EIGURE 9 disclo~es a front elevation view of the w~b severing mechanism shuwn in diffexent positions during cutting of the film wEb;
FIGURE 10 is an isola~ed enlI~3ed side view of the pre-stre~ching mechani~m of ~he invention;
FIGURE 11 is a bctbom view of the apparatus of ~IGU~E 10;
FIGU~E 12 is a top plan view of an alternate embodlment of the oonveyor assembly of the m vention;
PIG~RE 13 is a side elevational view of the apparatus of FIGURE 12; and EI~UFE 14 is a fr~nt cxoss-~ectional view ta`hen along 11nR
13'-131 o~ FIGURE 13.

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q~ best mode and prefexred ~bodin~t of the present ~sv~ion is disclosed in Figures 1 thr~ugh 3, 10 and 11, anf~l 5h~15 a ri~ wra~?~ apparatus ln ~prising a feed oonveyor 12, a wra~? and 5 lo,~ co~sve~or a~ribly 14, a film disp~nsing mechanism 16 with a c~tting nE~har~s~ lû ~ a take~off oc~nv~yor 20.
AS ~own in Figure 1, a pllLrality of cartons 22 forming a l~d 24 ~ lxen loaded in a stacked xel~ ship on an in~e~d canVeyQr assaTbly 12 by ei~her manual ox mech~nical means. It shauld ~e n~ted lQ that. the lc~d, aepending on its nature and composikion, may or may not r~.~m~r~ $pacing. The loading device 11 is schematically shown and may be one of a ~ er of ~ypes of stacking or plac ~ devices which are weli known in the art t~ place a stack of cartons or materials into designa~d ar~as~
In the preferred embodirent, the loa~ 24 is placed on an infeed conveyor 12 which is ~cmprised of an endless belt 26 m~unted on frame ~pport 28.
An alternate embodlment of the infeed oonveyor oould take the fonm of a hydraulic or pneumatic pushing devi oe (not shown) which ~an be ussd to en~age each load 24 with a pla~3l to push the load into the wrapp~ny area. However, the conveyor embodiment is preferred and the belts of the conveyor of the present in~ention are preferably ~extur~d so that ~hey have a high coefficient of friction.
The parti~ular arrangement of the conveyors set forth ~
Figures 1 and 2 lends itself to random ~ariatian of total load siæe in all three dimensions. It is apparent however that other configurations sould be oonstructed which w~uld be ~dvan~ageous f~r specific pro~ucts~
Thus, ~he conveyan oe of 12 packs or 6 packs of cans or bottles oauld be handled ~y a horizontal oonveyor with guide conveyors on each side.
The c3nve~or belt 26 as seen in Figure 2 is mcunted on r411ers 30 which are rokatably jourDalle,d.by suitable beari~g means in brackets which are secured to the rame ~upport 28. The infeed o~n~eyor 12 caxries the loads 24 onto a wrapping station 41 ccmprising a film dispensing apparat~s 16~ and a wra~ping con~eyor assembly 14.
The preferred emtodiment and best nDdR of the invention cc~pri~es a fra~e 42 on which a sbeel "d~nut" or ring-shap~d filn ~ f~ 7 5~

s ~ rt member 44 is rDtatably m~unted and supported on three planes by guide rollers 46. If desired, the film support me~ber can be oonstructed of alumlnum~ A plurality of guide rollers 46 project inward from the fr-dme 42 cn axms 47 and m~unting plates 48 o engage the rl~g-shapod nenter so that it can ~e driven in a predet ~ path. A
friction drive wheel 49 is positioned adjacent the ring nemker 44 at its base and e ~ ges the member 44 to rotate the me~ber 44 within the guide wheel rollins area. The fricti~n drive wheel 49 is driven by a m~tor 50 having a shaft which is suitably connected with a drive r0duoer 52. A
~aterial roll dispensing shaft 54 is rotatably secured to the rin~
member 44 ~or rotation on its axis and is adapted to receive and hold a rDll of fi~m material 56. A stationary ring 60 concen~ric with ~nd parallel ~o r.ing ~ember 44 is fixed to frame 42 on a side of rin~ member 44 opposibe that of ~ilm roll 56.
15 Typical films which can be used ~ the stretch wrapp ~
apparatus are EV~ c ~ lymer films with a high EV~ oDntent such as the films ~anufactured by ConsDlidated Ihermcplastics "RS 50", Bemis "Super'To~gh~, and PPD "St~y~Tight" films. PVC films such as Borden Resinite "PS-26" can be used in the invention along ~ith premium films such as Mkbil-X, Presto premium and St. Regis which utilize a new lcw pressure polymerization process resin ~anufactured by Uhion Caxbilde and DCW Chemical Co~pany. This resin, called 1 ~ear low density polyethylene, has si ~ fican~ly different stretch characteristics than previous stretch films. These characteristics allow the fi~m to withstand the high stress of extreme elonga~ion wi~hcut tearing dNring wxapping of the lold.
It sh~uld be not~d that fi~m, film material and fi~m web are used int ~ ngeab.ly throughout the specification.
The fi~m web is passed through a pre-stre~ching or elongation ~ ism 70 and is tucked or fastened underneath the lo~d or held in clamp a~sembly 62. The pre-stretshing mechani~m 70 which is best seen in Figures 1, 3, 10 and 11, oomprises oonnected roller memkers 72 ænd 74 which are rotatably mounted on respective shafts 73 and 75 which~are in turn jourT~lled into a housing 76. m e housing 76 is rotatably mounted on a pivo~ axle 61 journalled ~o the ring me~ber 44. The r~llers 72 a~d 74 are oonnected ko~ether by gears 77 and 79 which mesh tcgether and ~re dri~en as the filn w~b enga~es the rubber roller surfa oe s driving the .

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rollers. The gears 77 and 79 ~perate so that ~h~ film w~b passes first acr~ss ~he ups~ream roller 72 and then across t ~ ~ownstream roller 74 as it is pull~d from film roll 56 t~ the load 24, and the filn w~b drives the dbwnstream roller 74 at a fas~er rate than the upstre~n r~ller 72, causing the fil~ to be accelerated and stretched in a narrcw spaoe 80 between the two rDllers. me ratio of the gear 77 to the gear 79 preferably ranges from 4:5 ~o 1O4~ The pre-str~tching mechanism 70 is pivotable on pivot axle 61 so that upstre~m roller 72 i5 norma].ly uLge~ against fi~m rvll 56 in any well-~lcwn oonventional manner such as ~y a oDil spriny (not shGwn), which ~aintains oontact of upstream rolle~
72 and ilm rDll 56 as film pa~Gut reduces the diameter of film x~ll 56.
Contact of roller 72 and roll 56 prevents unoolltroll.0d payout of ilm w~b due to n~tum of film roll 56 upcn s~den dece!l~eration of r~ller 72.
Pa~er assistanoe asse~ibly 90 is bes~ ~derstood ~r referr~
to Figures 10 and 11. 5hafts 61~ 73 and 75 ~ter~ thr~gh housir~ 76 and ring 44 a distance at least equal to the distanoe ket~ r~ry r~g 44 and ~tatic~y rihg 60. Shafts 73 ar~l 75 pas5 ~hrough a slot 45 defined in ring 44, 50 that ~ihafts 73 ar~ 75 may pi~not ar~und shaft 61.
The pawer assistance ass~bly included a pcwer ~ransfer ass ~ ly 140 cc~pris ~ a oontact or fric~ion rDller 53 ~Lunted on the end of piv~t axle 61 so as to contact the surface of stationary rIng 600 Contact of r ~ 60 and r~ller 63 is ~aintained thro~ghçut the revolution of the ~oving "dcnut" ~r ring 44 because rings 44 and 60 are con~entric.
R~ller 63 is preferably made of .rubber or another material with resilienoe and a high ooefficient of fric~ion against the ma~erial of ring 60, wh~ch is preferably metal. me xe~ilien~e of roller 63 co~pensates for any ~ r e~nDrs in alignment or shape Gf r ~ s 60 and 44. T~e friction of rDller 63 against ~he ring 60 causes r~ller 63 to freely rotate cib3ut pivot c~x~e 61 on bearing raoes 62 while ring 44 is xotated. This frictional engagemen~ avoids the ~re exFensive alternative of placing gear tEe~h c ~ the surfa~e of rin~ 60, and replacing rDller 63 with a gear bo mesh with rL~g 60. R~ller 63 i5 locked in rotation with ~ransfer gear 64, both of which free wheel about piv~t axle 61.

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-fflmsfer gear 64 meshes with clutch gear 65 which free ~ls on ~str~rn gOE sh~t 75, which also exl:e~s th~lgh }~us~ 76. An adjustable o~nstant torque dev~ce 67 iS il~llll~l (~ shaft 75 adja~lt gear 65, and a pin 66 is ~rovid~3d to lock gear 65 ~o the ir~ p~te 68 5 of csonstant torque de~Tice 67. The output plate 69 of oDnstant ton~ue d~rice 67 is loc)c0d t~ shaft 75 and rotates with ~tream roller 74.
ffle adjustable oonstant to~e devioe 67 is pr~ferably a hys~resis c:lutc~ as m~del ~1 available off-~.shelf fmrn l)ana Industrial of We~ster, Massa~use~tsO Suc:h devioes acce~ an ir~3u~
10 r~tation thr~gh the input plate 68 ar~ supply an adjust~le oo~stant torque thr~h tl~e ou~sut plate 69. Iq~e amount of constant t4~e may be adjusted prior to wrapping 1:~ manipulatian of built~in oantrols attached bo aevice 67. m e ~pesd at which cutput plate 69 is ro~a~ed is independent of the speed at which input pla~e 68 is rc~a~0d, ~o that xotational speed of output plate 69 is determined by the speed at ~hich film is drawn acrDss roller 74 by rotation about the load. ~owever, becau æ energy is developed by roll~r 63 and transferred ~hrough gears 64 and 65 bo toxque devi~e 67, the cutput plate 69 suFplies a portion of the torque neressary to dri~e rollers 74 and 72~ and ~he portion supp.lied is a ccr~stant regardless of r ~ speed ~r load size. Thus, ~he force bo the load is reduoed, and held relatively constant regard~.ess of lcad size or corner passage.
It will be appreciated that gears 64 and 65 remain ~eshæd as ~he housing 76 piv~ts cn pivot axle 61, kecause the pivot aKle 61 and the downstrsam rol~Pr shaft 75 ~emain at a oo ~ nt distance ~n3m one another during pi~oting. I~exef~re, torque is prcvided by the constant ~Dxque device 67 regardless of the piv~ted posi~ion of hous ~ 76 or ~he di~me of ~ilm roll 56.
Because ~ s of substantially cylindrical cross-section draw film at a s~kstantially oonstant rate with minimal foxoe variations on film web 58 between rDllers 72 and 74, the pcwer assistanoe assembly 90 may be nodifie1 for these loads ~y ooupling of clutch gear 65 din~tl~
to roller 74~ This can be acoompLi~hed by locking or splining ge~r 65 to shaft 75, or by locking input platQ 68 b~ output plate 69~ Thu~s, the xDller 74 ~s force1 bo rotate at t~e speel of gear 6S. This effec~ively e~imina~es the boxque device 67 from power assistanoe asse~ly 90.

7S~

Ihe wrapp~ng ocnv~yor as~rbly 14 as best seen .in Fi~lres :1 a~ld 2 ca~prises two stacked co~veyors 92 ar~l 94. Ihese corn~eyors are st~ plate t~pe oo~v~yors ~æll ]ul~ .in the art o~?ris~ driven endless bel~s 96 and 98 ~unt~l on a pluralit:y of rollers 100. ~lhe 5 rollers are s~ppor~ed ~y plates 102 secur~ in t:ul:n to a :Era~ meTber ~not s ~ ) ~ ich holds the rollers ~n a rotatable position. The endless belt 96 is r~tated in a direction A sh3wn by ~he arrow in Figure

2 and frictionally engages the ~cp surfaoe of endless belt 98 to drive it at ~he same speed. Belt 98 is driven by a motor assembly 104 shown in Figure 1 which is oannected by ge~r me3n5 106 and linkage 108 in the fonm of chains or belts tD drive the oon~eyors, The ~pper belt segment of oonveyo~ 94 ~ravels downstream with ~he lcwer ~ t travelling upstream. The ~pper belt ~egment of oonveyor 92 travels ups ~ while the lçwer segment travels db~n~rtn~i~. The upper and/or lawer conveyor ean oomprise m~ltiple belts.
This construction allows a w~b of film to be wrapp0d around a load 24 which was carried from the in~eed oonveyor 12 onbo the wrapping station 41~ The stretched wrap of web is wrapped around the oc~veyor assembly 14 and the load with both the load and wrap being carried ky the oonveyor assembly in ~he same direc*ionu In the full web~ sp:Lral and kanding wcdes, the oonveyor asse~bly and wrapp ~ rLng is stopped, the clamp apparatus 62 cla~ps the film web and the cutter mechanisn 18 severs the film web. The oonveyor asse~bly 14 is ac*ivated ~arry.~ng the load and the wrap dbwnstxsan to a ~ake-off conve~or 20. When the load en~ounters t~e take-off oonveyor 20 as shcwn in Figure 2, the elonga~2d stretched w~ ~ off of the end of the c~nveyor ass0~bly assumes its me~ry position M against the load in ~he ~paoe between the oonve~or asse~bl~ 14 and take-off OQnveyOr 20, allowing the oontained load ccvered by strebched wrap to be carried away, As sho~n in Figures 8 and 9, the cut~ing mechanism 110 us2d in the preferLed e~bodimen~ and best m~db of the inven~ion inoorporatJes a driven piv~ted standard which is a~a~ted tD pro~ect upward tD engage the filn web between clamping apparatNs 62 and ~he load 24. The cutting mechanism 110 oomprises a ~ ort standard 112 which is piv~tally ~cunted at 114 tD a base ~Ember 116~ The base nEnber 116 can either be a part of frame 42 or be æ cured to frame 42. A pneumatic lifting cylinder 118 has one end xDunted ~y a suitable ~ar or bracke~ attachment to the ba æ ~neb3er 116 with ~he end of its piston r~d 119 at~a~hed t~

7~

the s~rt st~ 112 ~y suitable means such as a ~oke m~rrber 121.
~Jpon activatian of the pn~atic cylin~er, the upright standard 112 is transported in an arcuate path into the ~ T web 58. M~unted to the su~ort standard is a cutting asse~ly 120 c(xrprising a s~o~t pl~te 113, a pneunatic cylinder 122 n~unted to the suF~ort p~te 113, a~ a c:utting blade assç~rbly 123 n~t:ed to the piStCal rod 126 of cyli~er 122. ~ brush 128 is vertically n~unted on ~e suE~por~ plat ~ao b.ru~
d~n the trailing edge of the web against the oorlYeyor asserrbly. A
r~r 130 is positionRd in front of brush 128 bo pr~ect the brus~ base ~mm initial o~ntact with the film w~b ~nd <~nveyor ass~bly.
Upo~ a~pr~priate acti~ation, as for ~nple a predetermir~ nur.rb~ of revolutions o the r~ ~[~rber, ~i~h is s~l 1:~ an a~r~priate seIlsor cuttir~g ~ani~n 110 is prc~ll~ ward 50 ~lat the cuttirPg asssr~l~ 120 en~ages the îilm w~b~ ~3e b~de assenbly 123 15~ subsequently severs the fi~ b fmm ~e load. If desired, the cyli~ 118 can be activated after cutting to prc~el the stand~rd 112 fon~ard a ~t~nni~ distance causir~ the brush 128 to engage the r~3nai~er of the trailing edge of the fi~ b a~ wipe it against an underlying film l~yer.
q~he conve~or ass~ly 14 leads fra[l the infeed wrlveyor 12 to a take off o~ve~or 20 ~i~h is acnstructed liXR the infeed co~ or and xuns at the ~me spe~d as the ini~eed c~nv~yor. In order ~ ntrol b~h ccn~vey~rs at the same rate of speed, a suitable m~cha~cal means ~r~t sha~ is ~iet up to ~[~ t~ drive of both the infeed ~onve~r and the ~5 tal~off ~r~yo~ equal to ~e reductioal gear~ asse~ly of 'che drive mDtor. ~s, if the n~tor slaws down or s~ds up to drive t~e wraE~ir~
~hanism a~c ~;ffer~nt speeds, ~:he infeed and W~off oor~veyors are sin~ltan~sly sp~ded ~p or sla~ed d~ so that t~ load is ~3d to ~eyor asse~bly 14 and taken away fr~m the conv~yor ass~ly 14 at consistent x~l~tive ~d.
III an alt~rnate ~de of wra~in~, continuously ~ra~ped loads are taken off o:E the apparatus and are severed ~to s~parate load~s away fr~n the a~paratus. In this ~inert, the ta}Ge~ff ~eyor 220 carries the oantinu~usly spiral wra~d loa~ as shc~ ~n Figure 4 oonnected tL~gether b~ the film over~rap i~an ~he wra~ping statio~. The tal~ff oo~sveyor asse~bly 220 carries ths Spil~ undle ~to cutting aonv~yar 222.

?~ ~75Z
.
The wra~d .spiral bundle 224 as seen in Figure 4 is sev~
into indivi~al packages b~ a ~llotin~lilce cuttirg a~?aratus 225 cx~prisirlg a frame 227 and a cutter n~isr[l 229 slideably maunt~
the frame. ~e cutter m~chanism 229 ~nsists of a bcw fra~ 230 str~g with high nich ~ne wire 232 which is electrically c~nnected to a so~rce of enexgy. The resistanoe of the wnre causes suffici~n~ heat so that when ~he wire is reciprocabed bet ~ th~ encapsulabed loads 22~ bo cut them apart, the film material is simultan20usly b¢nded to ~he edyes so t~at the fi~m wQll ~ot unravel in shiFment. As ~he ~rapped loads 124 of the spiral bundle 224 enters the CUttLng area, a sensor 131 prDje~ts a light souroe thrcugh the transpar~nt film in a space S between the individual l~ads against a ne1ecbor 133 bo ge~era~e an elec~xical signal ccmm:nding the cutber blade drive c ~ try ~Q activa~e a pneumatic cyLinder 236. Upon activation, the hot cutter wire 232 is dri~en ~hrcugh the film to sev r t~e load 124 fram the wr~pped spiral bundle 224. Such SenSLng apparabus ale well kncwn in t~e art, and any standard cir~uit can be used bo cause the ~neuma~ic cylinder 236 to be activated ~hen the sensor senses a spa oe between loads 124. I~h~se, a l ~ t s~ t~h, CDntact switch~ pressure sensitive switch or other Z0 suitable mean5 can be used b~ activate the cylinder 236. In cper~tion the bow 230 is dri~en dcwnward during one cu~ and driven upward on the ~ext cut to prowide smooth, efficient operation.
The wire is ~ ~ ted ky CQnneCting it t~ a curxen source of abc~lt nine volts which heats the wnre sufficiently so tha~ the.e~es of the filn are bond~d to ~orm a hQlding ed~e. The severed edge stretches back to its original memory ~ e t4 form ~he ~Dldiny sha~e. The ~piral bundle advances and ~he nRxt sp~ ~ S ~etween ~e lo~ds 124 is sensed by the light SenSDr 131. The cutting wire 232 which has been pr~lio~sly driven ~cwn is lifted upward se~(ering the wra ~ loads in the s~
mannYr as previousl~ discussed.
Other c~tting apparat~s can be used in pla oe of the hea1 c~ltting wine, namel~ a kni~e blade with sawbQo~h edges secured to ~he frame in.plaoe of the cutter wireO When the bla~e is driven a~ail~t ~he film, the cut*ing edge strikes the wrapping material substan~ially causing the wrapping ~aterial bo shear. m e cutting is do~e while the wrapped ~undle is beLng translxort~d by ~he conve~rs.

.
~ n al'cern~te c~nv~yor ass~nbly erh~di~nt 300 can be used in plaoe of the cc~e~or ass~ly previously disclosed~ In ~is errb~
m~nt, the loatl carry~ belt 310 as sh~ in Figures 12 - 14 is positi~ned ~ver a ~el slider bed 312 which can be ~t:ably ~ted to 5 a fr~Te or ups~ sup~orts. Alst) secured k~ ~ frame or su~
are a steel base pl~te 314 with ~de rails 316 fo~d an each side ~cs fonn c~har~ to oorltairl 1:he r~und belt 318. ~ elt 318 is of ~
st~ard cx~ pe well la~ in the art. me load carryin~ belt 310 is ~nted an rollers 320, 322 and is driven ~y rc>ller 324 as is 10 well-k~n in the art. Belt 310, which is of the sa~ ~sitioq~ as the co~v~r belt which has previously b~en descri~l/ has a frictio~
surfaoe whi~h enables it ~ carry a load suita~l~ al~g its surfaoe.
I~e r~nd belts 318 an~ 31û' are respectively m~unted a~ dc~stre3m ys 326 ~hich are m~te~ to *~f~s 32~ ans of r~lle~ ~e;3r~
assellblies 330. The ~elt is positior~3d lty alig~r~t pull~ys 332 ar~d 334 ~e ~rar~ or in case of pullies 326 ar~d 332 to the steel slider ~d 312.
q~he r~und belts 318 a~ 318' are ~ted ~ ~e c~utside o:E belt 310 aran~d r~l} 322 and ~I:river r~ller 324. mus, it can be see~ t~at rather than us~ the lower cc~v~yor structure, whi~h has previ~sly ~en d~scr~bed, a r~nd belt oon~re~r is util~z~d which engages a~ly the ~ r ed~ f t:he fi~rl web wra~ed amu~ the conve~or ~ss~rbly. In this ~xiin~t *lere i5 a ~ dis~ce of app~tely ts~o to three in~es betb~ the end of the d~stxeam pull~y 326 to t~e edge o:E
roller 320 ~;o that t~ b of film will engage to a slight ex~t the t~ of the cc~ror ass~rbly. ~ver, sinoe the w~b is ~e~ carried forwar~, fricti~n for~xs d~ r~t ~ild up unli~ those of prior ar~
~ioes., qhe ~eration of the wra~ing a~?aratus is the sar~ as lthat of the prefer~ed ~din~t.

3 In the c~peratian of the inventive wra~ping a~?aratus, tl~ full w~b, spiral w~ib, anld banding modes of aperation a~e cperat~d in a s~stant:iaUy i~ ical mar~r.. In these ~des~ a feed oonveyor 12 br~s the load 24 o~ a~ping oor~ ro~ asse~ibly 14 whi~ t~
car:ries the lo~d to a predetennin~ wra~? positi~n ~nthin the fi~m 35 dispensing p~h and the a~rlv~yQr asse~ stops, lea~ the load in a stationary posi'cion. q~he leading edge 57 of the film w ~ 58 is held in clamping ~sse~bly 62 located beneath the conveyor asse~bly 14 as :is best seen in Figure 3. Rota~ion of ring 44 about the load is then b~3n.

1~?(~75~
As ring 44 rotate~, f.ilm is drawn fro~ film roll 56 across the surfaoe of noller 74 to encircle the load. ~s, the rotation speed of r~ller 74 is established by ~he linear speed of the film web being wrapped on the load. Thrcugh gears 79 and 77, the rotation s ~ of upstream rDller 72 is held to a constant ratio of that of dbwnstream roller 74, 50 that when upstream roller 72 oontacts film roll 56 and engages the film web, the filn web is stretched during passage between the rollèrs due b~ the speed differential ~here~betweenO
AS rlng 44 rotates~ the contact of rDller 63 with stationary ring 60 forces roller 63 to rotate, thexeby rctating transfer gear 64.
Clutch gear 65 meshes with transfer gear 64 and transfers energy to input platR 68 of constant torque device 67 through locking pin 66. m e output plate 69 of constant torque devi oe ~7 supplies a constant torque ~ downstre~m roller 74 ~hrcugh roller shaft 75~ Thus, the foroe expexienced by the load in its effort to dr~ film across ups~ream roller 72 and downstream roller 74 is reduced, and the variations in speed required ky the filn web due to oorner passage on the load is experienced without change in for oe on the film.
Alternativ~ly, if the load is substantially cylindri~al, the oanstant torgue device 67 may be elImina~e~ as descr~b~d above, so that clubrh gear 65 rDtates r~ller 74 at a constant ~pee1. The force experienced by the load in its effort tD draw film across rollers 72 and 74 is a~ain xeduoed, and speed var- tions are held to a muni~um by the shape of the load.
,~s film paycut reduces t~e diameter of film roll 56, the hous~ng 76 is pi~oted as no~ed a~cve to naintain contact of upstream noller 72 with film rDll 56. Sim~lt~neously, gears 64 and 65 remain meshed and the torque supplied thrcugh oonstant torgue devioe 67 remains constant regardless of the package siz~ or rate of ring rotation.
After at least one wrap has been made arou~d the load and the clamp assembly, the clamps are rotated releasLng edge 57 which is held by the fi~m web ~rap. If the wrap is for a full web load as shswn in Figure 5 or a banded lcad as shown in Fi~ure 6, a plurality of overlying layers of film are wra~ped arcund the load and the conveyor asse~bly 14.
In the spiral wrap mDde as shc~ in Figure 7, a plural n~rber of wraps are wrappad ar~d the d~wnstream end of the load as sh~n in phantom in Figure 7 .u~ ~he s~e manner as t~De banding in Figure 6 and ~he s:~onveyor as~semd~ly is activated carrying the load dah~stream to a take-of:E

75~2 conveyor so that a spiral wrap is formed arour~d the load. ~~n the loa~l reaches a station where ~ end is sensed ~ a feeler gav~e, light æns~ ~s, pressure sensitive sw~tch or ~ther suitable sensing ~cha~sm, b~th ~e ta}ce off corn~yor an~ veyor asserr~bly 5 stap and a sec~ ~nd is pla~ed ar~nd the upstream e~d of ~e load in the sam~ ~r as if a barx~ or ful 1 we~ wrap were be~ wra~l around th~ ls~ad. It ~uld be not~ hat t~Lere is a space ~etween tl~ conYeyor asse~rbly 14 and the W~off canv~yor 20 all~ the 5tretched ~Eilm web to be discharged ~m t~e ocxnv~yor ass~ibly ar~d ass~ne its ~ry 10 position M ~ the l~ad.
me er~d of the wra~ c~cle is d~termi~d in the present inYentic~ ~y a pmKimit~y switch locat~d a short distance c~c~y frcrn ri~g 44 ~ich senses a ~ent m~tal plate secured ~o the rirlg. me pr~x:~ni~
switch is electrically ao~nect~d to a ~unter whi~h i.s activated to 15 deterrni~ eac~ revolutic~ of wrap. The particular ~unter which is util~ed is an Eagle c~n'cer, ~del D21ûO ~G, whic~ is an off~ shelf standar~ c~a~. ~en the cDunter has i~3icated a prede~mired n~rber of revolutioxls de~rmin~ che t~pe of wrc3p ar~ the loacl desired to ~e wrc~, the oounter activates a swi~h ~ic~ st~s the 20 take off ccs~v~or an~ w~ir~ OQrn~eyor asse~bly for cutting of ~e film web. The activation of t~e flu;d cylir~rs to f:ire in a predete~mined order ar~ ~t~l a ~redetermin~d dist~noe is well lm~wn in the art and can be as~oonplished b~ alr~n fluid circuitry.. ~en the cutter n~chanisrn is acti~ated, the cuttex sta~rd ar~ head is c~ upwar~
25 and ~buts ~e film cæry~ ~e :ilm ~ the l[ud~lle of the load. It sho~ld }:e ~ted that the disper~;ing roll 56 ~ ring 44 in the stx~p posi~ion is located ~clerr~ath ~e lo~ and is subs~cantially perpe~cular ~ the axis of the load. ~en t:he film r~ll has b~#~n positioned ~ thi~s mann~, ff~e web itself has enga~ed e~ther the load 30 edge or oarn~or ass~bly eclge and is angled fran the edge ~n 1~awards the roll p~siti~ned cn the rin~ he cutter ~hanism 110 w~ driven upward ~y the F~tic ~lirx3er 113 engages the angl~d fi~ b and carries it into s~stantial c;~ ormanoe with a perper~icular lin~ dra~
fr~n the center axis of the corn~or asser~ly with ~e bru~ 128 3S bru~hing the fi~m d~ aver an uru~rlying film layer wra~d ar~ the conveyor ass~ly as is ~n in Figure 9. q~e clamping me~anism 6? is t~n rotat~d t~ clanp and hold ~e film w~b be~n ~he cutter ~ad 120 and the di~ensing r~ll 56. The pn~a~ic ~yli~er 122 of the cutting head is then f~3d, driv~ng a s~w~th cutter blac~ 221 inbD 'che film web 58 to ~ever the film web. ~en the film w~b is severed~ a srr2~11 portior~ of tl~ trailing edge is left hanging :Eree fran the wrap. If desired, this film edge may ~e wip~3d onto the load l~y firing the cNtter standar~ c~rlin~er 118 a secor~l ti~ so that ~che star~ard n~ves a short distanoe ~urth~r on carrying the brush on bo wipe the remnant edge against ~he wrc~pO Ihe c~tter stc~ndard is then withdrawn away frcm the load ~to a rest position as sh ~ in phantom in Figure g for the next cutting ope~a~ion and the con~eyors are activ~ ~o carry the wrclpped load awa~ frcm the wrapping static~ and a new load into the wrapping E~tati~n. , In the oontinuDus wrappLng cperation, the previously descr;J~3d cutter m~nism is not usedc~nd the loads are oontLn~ly carri~
along the ~rc~ ing oonveyor as~bly onto a take-off conveyor whi~
~paoes the 1~ for severing dcwns~m. ~le loadsc~re then sev~ed beb~ the spaoed film areas as previously di~cus~ and taken ~y t~
an~ trnns~t area.
It can be seen that the invention provides a novel and useful improvement over the prior art rotating wrapping machines, both those utilizing brake stretching systems and those utilizing coupled roller stretching systems. This is advantageously accomplished without the need to transfer electrical power or control signals from a stationary source to devices such as brakes or motors on the rota~ing r~ng.
Most plastic films when stretched above their yield point gain significantly in modulus and ultimate strengl:h.
The typical polyethylene will multiply three times the ultimate strength in pounds per square inch of cross sectional area after being elongated approximately 300 percent. This significant increase in strength begins approximately when the yield point is exceeded in the elongation phase. Limitations of friction-based constant force devices prevent currenl:
stretch wrap applications from achieving the higher levels of containment force and ultimate strength available in the oremost plastic films. Achieving the higher elongation levels with the invention allows fewer revolutions of film with equivalent holding power. These higher levels of stretch not only allow fewer revolutions of film but also less film by weight for each revolution.

~,f~ 5~

Thus, it is be:Lieved that the present apparatus allow.s at least double the practical level of elongation currently experienced with prior art "brake" systemsO This gives higher containment forces and/or lower film costs to the end user.
Furthermore, preferred apparatus allows for more precise control of elongation allowing the user to get maximum cost efficiency from high yield films, along with higher film strength or modulus achieved at higher levels of elongation.
The higher levels of elongation are achieved on the film without disruptive or crushing forces on the load because of the mechanical advantage experienced between the pulling force to the pallet and the force between the rollers further supplemented by the constant torque assistance.
The novel construction of the apparatus provides for isolation of the film roll from stretch forces which eliminates premature film failure from roll end damage or roll down of edges under force. The use of ~his simplified construction eliminates the use of friction brakes and the problems of those brakes such as speed variation, break away from stop position, temperature variation, wear and operator control meddling.
The use of the film web for speed control as opposed to motor driven devices also eliminates the need for compensation devices for corner passages, length/width variation or roller rotation speed variation, as well as eliminating tension compensation devices.
It can thus be seen that a unique apparat~s and process are provided in that two xollers interconnected for constant speed ratio are speed-controlled by film drawn to a load. The film is stretched beyond its yield point as it accelerates between the rollers. A constant portion of the force is provided by film drawn to the load, and an additional constant portion of the force is provided by the power assistance device. Higher forces achieved during pre-stretch are slightly relieved between the downstream roller -- 19 ~

s~

and the load producing inelastic strain recovery since the film i5 stretched above its yield point. The present apparatus essentially eliminates the neck down of the film we~ normally experienced at high elongation rates. By lim~ting the stretching action to a minimum di~tance between the rollers and avoidinq secondary stretch betwe~n the second roller and the load, web neck down is significantly reduced.
In the foregoing description, the invention has been described with reference to a particular preferred em~od.iment, although it is to be understood that the specific details shown are merely illustrative, and the invention may be carried out in other ways without departing from the true spirit and scope of the following claims:

.. .. .. . _ _ _

Claims

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. An apparatus for making a unitary package using a single web of stretchable plastic material to form an overwrap, comprising: a frame; a dispenser means mounted to said frame, said dispenser means being adapted to hold and dispense a roll of stretchable material; drive means adapted to drive said dispenser means in rotation about a load;
elongation means connected to said drive means and adapted to receive and engage stretchable material pulled from said dispenser means, said elongation means comprising at least a closely spaced apart downstream roller and an upstream roller interconnected by speed control means;
said elongation means being driven by said drive means and by engagement of the stretchable material pulled from the dispenser means during rotation of the dispenser means about the load, said upstream and downstream rollers being acted upon by said speed control means so that said downstream roller transports said stretchable material faster than said upstream roller to cause said stretchable material to elongate between said upstream and downstream rollers.

2. Apparatus as claimed in claim 1 wherein said elongation means is adapted to maintain contact between said upstream roller and said roll of stretchable material during payout of said stretchable material.

3. Apparatus as claimed in claim 2 wherein said upstream roller and said downstream roller are adapted to maintain a constant distance between one another during payout of said stretchable material.

4. Apparatus as claimed in claim 1 including power assistance means comprising power transfer means and predetermined torque means, said power transfer means being coupled through said predeter-mined torque means to said elongation means.

5. Apparatus as claimed in claim 4 wherein said predetermined torque means is coupled to said downstream roller.

6. Apparatus as claimed in claim 4 wherein said predetermined torque means is adjustable.

7. Apparatus as claimed in claim 4 wherein said power transfer means comprises stationary ring means and transfer roller means, said stationary ring means being secured to said frame, said transfer roller means being coupled to said dispenser means and adapted to be rotated by revolution of said dispenser means relative to said stationary ring means.

8. Apparatus as claimed in claim 4 including transfer gear means and wherein said torque production means is coupled through said transfer gear means to said predetermined torque means.

9. Apparatus as claimed in claim 1 wherein said speed control means comprises upstream gear means and downstream gear means, said upstream gear means being coupled to said upstream roller and said downstream gear means being coupled to said downstream roller, said gear means being meshed to define a constant speed ratio of said upstream roller to said downstream roller.

10. Apparatus as claimed in claim 4 wherein said predetermined torque means comprises a hysteresis clutch.

11. An apparatus for providing an overwrap to unitize a load by dispensing a stretchable film web to encompass the load, comprising:
a frame; conveyor means attached to said frame, said conveyor means being adapted to carry said load through said frame; rotary ring means rotatably mounted to said frame; drive means adapted to drive said rotary ring means, dispenser means mounted to said rotary ring means, said dispenser means being adapted to hold and dispense a roll of stretchable film web; pre-stretch means mounted to said rotary ring means adjacent said dispenser means, upstream roller means and downstream roller means rotatably mounted to said pre-stretch means;
speed control means connecting said upstream roller means and said downstream roller means so that said downstream roller means and upstream roller means rotate at a constant speed ratio such that said film web passes across said upstream roller means at a first speed and said downstream roller means at a second speed higher than said first speed; and power assistance means connected to said pre-stretch means and adapted to derive predetermined torque from rotation of said rotary ring means and to contribute said predetermined torque to drive said pre-stretch means.

12. Apparatus as claimed in claim 11 further comprising stationary ring means mounted to said frame in coaxial relationship with said rotary ring means, and wherein said power assistance means comprises power transfer means and predetermined torque means, said power transfer means comprising transfer roller means, said transfer roller means being mounted to said pivot axle and adapted to derive rotational energy by revolution of said dispenser means relative to said stationary ring means; said predetermined torque means comprising an adjustable predetermined torque means having an input plate and an output plate, said transfer roller being adapted to transfer power during rotation of said rotary ring means to said input plate, said output plate being adapted to transmit predetermined torque to said downstream roller.

13. Apparatus as claimed in claim 11 wherein said power assistance means is adjustable to alter said predetermined torque.

14. Apparatus as claimed in claim 11 including wrapping conveyor means adapted to support said load within said rotary ring and carry said load and said film web encircling said load and wrapping conveyor away from said rotary ring.

15. Apparatus as claimed in claim 14 wherein said wrapping conveyor means comprises upper conveyor means and lower conveyor means, said upper conveyor means having an uppermost surface adapted to carry said load in a first direction at a first conveyor speed, said lower conveyor means having a lowermost surface adapted to carry said overwrap in said first direction at said first conveyor speed.

16. Apparatus as claimed in claim 11 wherein said power assistance means comprises power transfer means and predetermined torque means, said power transfer means being coupled to said predetermined torque means, and said predetermined torque means being coupled to said pre-stretch means.

17. Apparatus as claimed in claim 16 wherein said predeter-mined torque means is coupled to said downstream roller means.

18. Apparatus as claimed in claim 16 wherein said predeter-mined torque means comprises adjustable predetermined torque means.

19. Apparatus as claimed in claim 17 wherein said power transfer means comprises friction roller means, said friction roller means being coupled to said pre-stretch means and interacting with said stationary ring means to rotate said friction roller means during rotation of said rotary ring means about said load.

20. Apparatus as claimed in claim 16 including transfer gear means coupling said power transfer means to said predetermined torque means.

21. Apparatus as claimed in claim 18 wherein said adjustable predetermined torque means comprises a hysteresis clutch.

22. An apparatus for making a unitary package by dispensing a web of stretchable film web to form an overwrap, comprising: a frame;
ring means rotatably mounted to said frame; a dispenser means mounted to said ring means, said dispenser means being adapted to hold and dispense a roll of stretchable film web; said ring means providing rotation of said dispenser means about a load; elongation means connected to said ring means and adapted to receive and engage unstretched film web from said dispenser means, said elongation means comprising at least a downstream roller and an upstream roller, said elongation means being adapted to transport said film web across said downstream roller at a varying downstream speed substantially proportional to a speed at which said film web is wrapped about said load, said upstream roller being adapted to transport said film web at an upstream speed which is a fixed fraction of said variable downstream speed so that said film web is stretched between said upstream and downstream rollers; predetermined torque means connected to said elongation means and engaging a track means, said elongation means being driven by said predetermined torque means rotating along said track means and by engagement of the film web pulled from the dispenser means during rotation of the means about the load, and drive means adapted to drive said rotary ring means and said predetermined torque means.

23. An apparatus for wrapping a load with a stretched film web to form an overwrap, comprising: rotary ring means; dispenser means mounted to said rotary ring means, said dispenser means being adapted to dispense film web; said rotary ring means being rotatable to provide rotation of said dispenser means about a load; elongation means connected to said rotary ring means and adapted to receive film web pulled from said dispenser means, said elongation means comprising speed control means and at least a downstream roller and an upstream roller closely spaced apart and interconnected by said speed control means;
power transfer means coupled to said elongation means, said elongation means being driven by said power transfer means and by said film web pulled from said dispenser means, said power transfer means comprising stationary ring means and transfer roller means, said transfer roller means being adapted to interact with said stationary ring means to rotate said transfer roller means during rotation of said rotary ring means.

24. Apparatus as claimed in claim 23 wherein said power transfer means further comprises a hysteresis clutch coupled to said transfer roller means and to said elongation means.

25. Apparatus as claimed in claim 24 including transfer gear means, said transfer roller means being coupled through said transfer gear means to said hysteresis clutch.

26. Apparatus as claimed in claim 23 wherein said speed control means comprises upstream gear means and downstream gear means, said upstream gear means being coupled to said upstream roller and said downstream gear means being coupled to said downstream roller, said speed control means being adapted to rotate at a variable speed and said fixed fraction of said speed of downstream roller.

27. Apparatus as claimed in claim 24 wherein said power transfer means is coupled to said downstream roller.

28. Apparatus as claimed in claim 23 including wrapping conveyor means comprising upper conveyor means and lower conveyor means, said upper conveyor means having an uppermost surface adapted to carry said load in a first direction at a first conveyor speed through said rotary ring means and said stationary ring means, said lower conveyor means having a lowermost surface adapted to carry said overwrap in said first direction at said first conveyor speed through said rotary ring means and said stationary ring means.