CA1077319A - Apparatus for forming a convoluted container sidewall - Google Patents

Abstract

APPARATUS FOR FORMING A CONVOLUTED
CONTAINER SIDEWALL

Abstract of the Disclosure Apperatus for wrapping a sidewall blank about a mandrel utilizing two wrapping wings which are rotated about the mandrel axis by respective drive trains, each drive train comprising a shaft positioned coaxially with the mandrel, a lever arm connecting the wrapping wing to the shaft, a slide member positioned in a trans-versely extending slot in a common reciprocating carriage, and a crank arm secured to the shaft and pivotably connected to the slide member. One of the wiping wings can be provided with an L-shaped blade with one leg of the L-shaped blade extending forwardly in the direction of travel of that wiping wing during the wrapping operation to lead the blade of the other wiping wing.

Description

27~,35 :~3'7~

APPARAT~S FOR FOKMING ~ CONVOI.UT~D
CONTAIN~R SIDEWALL
This invention relates to an apparatus for wrapping a sidewall blank about a mandrel to Eorm a convoluted sidewall.
Numerous machines for wrapping a sidewall blank about a mandrel have been designed to employ a two-element or three-element clam shell mechanism for folding the blank about the mandrel. However the clam shell mechanism tends to slap the mandrel at the conclusion oE the fold-ing operation, causing noise and substantial machine stress. The clam shell mechanism also permits undesirable variations in the diameter of the formed tubular bodies. These difficulties can be avoided or at least minimized by employing two wrapping wings which are rotated about the mandrel axis to wrap the blank about the mandrel. However, when a blank is wrapped about a mandrel by using two wiper blades starting at - locations intermediate the side edges of the blank, some means for wrapping one side edge ahead of the other side edge is necessary to achieve an overlap of the side edges without damaging the blank. This can be accomplished with each wiper blade being controlled by its own individual cam and lever system. However, rotary cams are expensive to ~` design and to manufacture, and are not adapted to adjustments. Frank P.
Richards, U.S. 3,958,501 discloses an apparatus for operating the two wiping wings wherein a lost motion mechanism permits the rotation of one of the wiping wings to be terminated before the opposite side margins are overlapped by the continued rotation of the other wiping wing.
While this apparatus has the advantage of ease of design, construc-tion and adjustment, the operation of the apparatus results in a high noise level. Substantial noise results from the resiliently mounted drive rod striking the metal stop pin, the flexing of the heavy duty spring on the resiliently mounted drive rod, and the backlash from the rack and pinion gear.

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~ccordingly, it Ls an oblect of the present invention to pro-vide a new and Improved apparatus for formi~g a convoluted tube.
Another obJect of the invention is to provide a drive mechanism for two folding wings which does not employ rotary cams to diEferentiate between the rotation of the two Eolding wings. ~nother ob~ect of the invention is to provide a dr-ive mechanism for two folding wings which has a low operation noise level. Other ob~ects, aspects and advantages of the invention will be apparent from a study of the specification, the draw-ings and the appended claims of the invention.
In the drawings, FIGURE 1 is a diagrammatic representation of a container forming machine embodying the present invention;
FIGURE 2 is a plan view, partly in cross section, of the ; mechanism of the sidewall wrapping station of FIGURE 1 in the open position; ' FIGURE 3 is a plan view, partly in cross section, of the mechanism of the sidewall wrapping station in the closed position;
FIGURE 4 is a partial elevational view in cross section taken along the line 4-4 in FIGURE 2;
FIGURE 5 is a cross-sectional view taken along line 5-5 in FIGURE 2; and FIGURE 6 is a cross-sectional view taken along line 6-6 in FIGURE 4.
Referring now to FIGURE 1 in detail, thermoplastic coated paperboard sidewall blanks 11 are individually withdrawn from magazine 12 and transferred to conveyor 13 by sidewall feeder 14. The blank 11 is passed through sidewall heater 15 to heat to a suitable bonding temperature the thermoplastic coating in the side marginal positions which are to be overlapped in the formation of the sidewall into a con-talner and, if desired, in the bottom marginal position which is to be bonded to the botto~ member 16. Turret 17 is mounted for rotation aboue lts horl~ontal a~l~ and 1~ provldod with a plursllty of m~ndrels 18 whl~h extend rndl~lly outwnrdly from ~aid hori~ontal ~x18 4n n vartlcal plane perpendlcul~r to ~ald horl20ntal n~i~. ThQ ~androl~ 18 ~r~ ~pDc~d ap~rt on th~ turr~t 17 ln ~ nnl~or~ n~n~ar. A s~ltabl- botto~ P~d~r mech~nls~ 19, for ~x~mpla ~ chlp ~dor, ~upplie~ ~ndl~ldu~l boet~
me~b-r~ 16 to tbY outQr~o~t ~nd ~c~ of ~andr~l~ 18. E4~h ~Qndr~l 18 f~ provld~d with ouitabl~ ~ean~ for ~ ~pl~ suctlon ~aDs, to hold th- ~otto~ mEmb~r 16 in plscc o~ tha e~d f~ce of th~ ~antrel. Sh~ turrQt rotate~, at~p~ioe, 1~ 5 clockwi~o dir~ction ~ ~f~wcd ~ FIGURe 1, to ~uYo a b~r~ ~aDdrel eo the botto~ fsading ~taelon to r~cd v~ a ~otto~
s~ber 16 a~d then to tho horizontsl po~ltlD~ i~ a~lg~ment ~ith ~o~v~or ~an~ 13 to recQiv~ ~ heat~d blank 11. B~ch ~dral 18 ~ a aid~d l cl~p 21 assQciated thor~with ~hlch ~8 ln th~ opQn po~ltlon, ~p~c~d apart fro~ lts ma~dr~ 8, ~t cha ~idawsll blan~ s~c~ g ~tatlo~ to per~t th~ h~st~d b~snk 1~ eo ba ~n~srted ~ee~ee~ tho ~andr~l 18 M~d cls~p ~1 by oDn~e~or ~an~ 13. `The cl~p 21 1~ tha~ nct~at~d to oec~re th~ ~edian or i~t~r~Qdl~t~ port~o~ of ~ hest~d bl~k 11 i~ pos~tlo~
on ~a~arQl 18g ~fter v~l~h the tusrQt 17 1- l~d ~d to tb~ ~se po-ltio~ to carTy th~ ~cur~d ~ k ll ~d ~ott~ ~exb~r 16 to ~b~
: 20 id ~ l ~rapping tatlon. The ~id~N~ll wrapp~ 2~0 22 ~r~p~ t~
~lADk 11 arouDd ~andrel 18 to form co~ol~t- ~d to appl~ pr~s~u~ to t~ overlapped heat~d ~lde ~ar~ins to bond the ~a~ ~ar~ln~ t~Qræb~ .
- formlng a tubular oldFwall 23. ::
: ~t ths neat ~nd~slng of turr~t 1~ tho ~s~r~l earryi~g the .
: ~ubular ~id~all 23 S~ ~o~a ~ro~ th~ sidsw~ rApping ~e~t~o~ to thQ
b~tto~ Saatlng stat:lon, ~h~r~ ~he ~s~ of thc ~id~all ~d~c~nt ehc botto~ R~bar 16 1~ hoat~d ~y botto~ heatinB m~an- 24 to ~ ~ult~bla `~ ~oDa~Dg t~ratura. Tha eurr~t 17 ~B thc~ l~de~*d to tranJport th~
~andral 18 a~d th~ h~atad dd~usll 23 to ~ ~otto~ ~4allng ~tation, ~h~re botto~ ~all~ D~n~ ~5 ~ppllos pro~u~s to th~ ~eat~d postlo~s ~ 3-.

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Or tbe ~de~ll 23 ~nd boetom Dlember 16 to for~ th~ bottom seal. ~I~ one embodimene ebe bot~om ~a~ab~r 16 ha~ ~ sbsp~ ~t l~ast ~ubs~ant~lllly ~quAI
to ~he h-pe of tbo ~ f~ce of wn~r~l 18, aDd the bott~D nar8in o~ the tubul~ dd~ll 23 ls ~old~d lnw rdly lllto contact v~th th~ bDttom ~bDr 16 to for~ thls bottam ~e~. A coDtainor of thlo typ~ llu~
tr-ted b~ I. L. ~llc07~ . Paton~ No. 3,369,726, ~0~UQd Febru~r~ 20, 19~8. I~ ~soth~ D~lt the boltto~ r 16 can bo ~or~d ~th a cantr l dloe portlo~ h~ring ~ di~t~r ~ubst~tiall~ ~qual to the d~ter of th~ s~d fac~ o~ dr~l 18 ~n~ ~n s~ular fl~nge portion i~ ~ 10 fold~d to e~t~ ol~t~rtly rom tha ~rsdrel 1~ t l~ast approximat~
parall~l to tha ~da sllrfaco o~ th~ dr~l 18. I~ th~ latt~s aDbodl-~t ehe fl~nge pore~ of th~ ~otto~ ~ember ~6 ~s~ be bond~td to t~
contacti~g ~ ac~ of the t~bu~r lde~ll 23. It d~s~red, th~ tubular otto~ n~rg~ ean b~ lo~gcr tl~n t~ f~ng~ of bottom ~diB~ 111 .

b~r 16 to penn~t t~ ~otto~ ~sg~n to ~e folaed appro~clmately laO to for~ hlch cont~ets l~oth ~ie~ o~ t~ fla~gc of bo~to~ ~r 16.
If ~lr~d, th~ botto~ ~ eAn ~ rollo~ b3r ~rulta~lo ks~ a~O
Whcr~ eh~ botto~ ~be~ 16 i2~ flaDg~d, bott~ f~edor ~Ig c~s enplo ;- ~ucelon eup ~r~f~ n~ch~ t dl~ca ~n ~e c~ip fed a~d tl~e~
20 forced tbrwJgb a die to for~ ~h2 fl~z ~Dd the~ ~ppll~d to t~e end face of ~dr~1 18.
hfter t~ botcors sl~l lo fo~ned, th~ twrr~t 17 1~ ~o~ed to tras~port th~ fons~d con~r 26 rO fi strippiD8 ~ta~i~, sQd ~h~ 80 ciat~d cl~p 21 1~ ~oved to eh~ op~ po~tiou to relea~ th~ ta~er 264, Altbs~ugh ~ ~ult~ble ~echani~al strlppir~ ~ ~ b~ e~plol~ed5 It :: ia prewntly pt~ ble eo ut~ e pfieu~tlc pree~urQ appl~ed tbrou~h the ~ndr~l to tbe ~ a of th~ cont~i~er to ~d~¢~ th~ t~lner frc~ :
th~ pocka'c of turr~t 27. ~urret 27 la rotata~
~tep~o~ s~out horir~l JaS18 28 to ~r~ tha ~e¢ted coneain~r 25 ~ro 30 th~ ~l hort~ontal pode~o~ to ~ v~rtlc~ podt~o~ ~lth tEts ope~

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end up. ~ pu~her arm 29 1~ ~ovad thr~ugh the upright poc~et of turret 27 to ~o~e the c~nta~n~r 26 onto conve~o:r 31. If de~ir~d, t~ conveyoro can be pooltioned on oppo~lte olded o~ turret 27 and pu~hQr ~r~ 29 can move alt2r~at~ cont~iD~rs to oppo81ee conv~yora.
Ref~rrlng no~ to ~IGURE 4, bottom me~ber 16 1~ illustrated as h~vlng ~ centrsl dlec port~sn 32 and ~ snnular flange po~lon 33 and ~8 beld ln plsce o~ the end f~ce of mandrel 18 by th2 ~ubatmospheric pr~s-: sure mainta~ned ln ~onduit 34 and lts brenche~. ~prlng bia0ed ~iplng blades 35 and 36, carrled by foldlng wing 37 ant 38S ~e~pectivelyt con-~act the o~t~r surface of ~ld~uall bl~#~ 11 on opposlte altæ6 of e~e re~p~ctlve cla~p 21 ~hen ~andrel 18 18 ind~xed l~to the ~id~wall wrap-plng statl~n. The foldln~ ~lngs 37 snd 38 are then actust~d to rotate about the longltud ~ 1 a~ls o~ the ~a~dr~l 18 ~n oppo~lte directio~
at ~n at l~ast subst~ntlally ou~t~t di~taace ~ro~ the loDglt~diQal asi~ of the ~9ndrel 18 ~o ~rap the ~ide~all ~l~n~ round ~andrel lB
~ith one s~d~ ~argin o~ blan~ 11 Dv~rlapping the oppo~it~ side ~r~a ~-o~ blan~ 11 to fora the eonfolut~ conCalnar ~idewall 23. The le~di~
edge of blade 35 can be ro~toed ~ ~dvane~ of tb~ l~ading ~dge of bl~de 36 by a ~e~ degrees to th~t blade 35 cau~e~ the le~t etge port1on of ~de~
~all blan~ 11 to fold a~aia~t mn~trol 18 ~fore bl~d¢ 36 f~ld3 the ri8ht edge portion of Uan~ 113 there~y c~w 1D~ the rigbt edge portlon of blau~ o overlap the leEt edge portion thereof. Wh~n the rotation of blades 35 ~nd 36 1~ co~pleted~ ~eallng head 39 1~ ~ctuat~d by pisto~ ~0 ~f pDeu~atl~ cylinder 41 to pr~es the beated right oedgQ portloa of : blnn~ 11 ag~ln~t t:he heat ~ left edBe p~rt~oa thereof to achleYe a thermal bondi~g of the thermopla~eic coati~gs ~d there~y form the co~-voluted container ddc~All 23. For sak~ of s$mplieity t~e ¢ylinder 41 18 3hD~ pqrpendlcul~r to ~eal~ng hea~ 39 and dlreetl~ connec~d thereto.
~oYnyer~ ~n a pres~ntl7 pre~erræd em~3di~ent the egllDder 41 i~ mou~ted on tha fr~mo ~ a stAt~onary positlon ~ppro:Rimatoly par~ l to ~eall~g - s :
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1l~'7'7 ~L~3 he~d ~9 wh~n he~d 39 i8 in the 88alin~ po~ltlon. A plvot~d rocker arm mechani~m, ~hirh 1~ ~ounted on ~old~ng win~ 38 and operate~ ~e~ling he~d 39 vls a sprlng bla~ plunger, rot~te~ i~to po~itioD to b~
operatad by the pl-ton 40 o~ cyllnder 41, eh~rebg ~r~nolatl~g the ~otlo - of the piston 40 of cyllnder 41 ~pproxi~Qeely 90- to move the ~ealing head ~9 a8a~nst the ovorlappQd 8id~ u~rgiu~ of blsnk ~1.
Referrlng no~ to F~GURES 2-6, the ~ctuatlDn mechanl~m of ~lde~
wall ~rspp~ng D n~ 22 c~mprl~es a carr~age 42 whlch 18 mounted for ~or-~rd ~d retractlve ~otlon by ~leeve bear~ng~ 43 ~d 44 o~ gulde rod~ 45 ~nd 46 secured to hou~l~g 47. The ~otion of carrlnge 42 1~ efected by coupllng 48, which i8 actus~t ~ 08ClllAting shaft 4~, yok~ 50, con~ect-~n8 l~n~sge 51 ~nd yoke 52. Shaft 49 ean b~ o~cillat ~ ~y ~ rotnr~ CE~
:~ ln tSe ind&~lng ~¢c~anism (not ~ho~n) for t~rret 17. Carrlage 42 h~ ~
flrs~ open~ng 53 therethrough extending ln the dlr~ctio~ of the recipro-c~ting tlo~ of carrl~gQ 42. A shaft 54 i~ poslti~n~d ln op~nln~ 53 80 88 to be coaxisl wlth ~nd a~lQll9 8p~Ced fro~ t~s ~aodr~l 18 ~h~h 18 ln tha sldeball blADk ~rapplng ~tation of turret 17. Opo~ing 53 1~
suff~clently l~rRe in both the l~gieu~nai and trs~svor~e directl~ to - preYe~t iDterfer~nce bet~ee~ carrlsge 42 an~ shaft 54. -~ ~leere ~haft 55 i~ mounted ~oaxlally with ~d ~urround~ng an lnten~ed~te portlo~ of shAft ~ by ~Rans ~f bush~ngs 56 ~nd S7- The upper end o~ sha~t 54 18 ~ Dounted in bushlng 5~ in a cross bar S9 whic~ e~tent~ bet~e~n oppo~lt~
sides of hou~lng 47. A bushlng 61 is posltloned betw~en ~leo~e 55 and cylindric~l euppore w~ll 62 whlch is ~lded to cro~-b~r 63 ~hich exeena~ between oppo31te ~ldes of hOU81ng 47- Wrappin~ wing 37 le con-: nected to thc lo~r end of ~h~ft 54 by ar~ cl~mp 64, ~hile Ur8pp ~lng 38 1B ~onnected to the lower end of ~leev~ shaft 55 b~ srm cla~p 65 Arm C1J~P8 64 snd 65 ~re p~ovlded with ~u~table ~e~ns, not ~ho~n, for fix~d ~ngage~ent ~lth ~ha~t 34 ~nd ~leeve 55, respectl~ely, 0uch th~t the rotation o~ ~h~ft 54 ~nd ~12eve S5 effects the correspond~ng rotation o~ arm clamps 64 and 65. Suitable engaging means lncludes keys in keyways and set screws.
Carriage 42 is provided with lLnear slots 66 and 67, which ex-tend along a straight line perpendlcular to the direction oE recipro-cating motion of carriage 42. One end of lever arm 68 is secured about shaft 54 for rotation therewith, while a slide means, e.g., roller 69, is positioned in slot 66 and is pivotably attached to the other end of lever arm 68 by shaft 71. One end of lever arm 72 is secured about sleeve 55 for rotation therewith while a slide means, e.g. ? roller 73, is positioned in slot 67 and is pivotably attached to the other end of lever 72 by shaft 74. A thrust bearing 75 is positioned about shaft 54 between lever 68 and bar 59, while a thrust bearing 76 is positioned about shaft 54 between lever 68 and carriage 42. A thrust washer 77 is positioned about shaft 54 between carriage 42 and sleeve 55, while ` thrust washer 78 is positioned about sleeves 55 between lever 72 and ;~ support wall 62.
` Referring now to FIGURE 6, wiping blade 36 is resiliently biased in the frame of right folding wing 38 by spring means 81, while wiping blade 35 is resiliently biased in the frame of left folding wing 37 by spring means 82. Wiping blades 35 and 36 can be formed of any suitable material which will not damage the surface of the blank 11, e.g. nylon.
In a presently preferred embodiment, blade element 83 is a 1/8-inch thick flat bar nylon element having the blank contacting surface curved in the form of a semicircle having a 1/16-inch radius and mounted on a steel backup bar 84, while blade 35 has a nylon element 85 having a `~ generally L-shaped configuration mounted on a steel backup bar 86, each leg having a thickness of approximately 1/8-inch. The long leg of blade element 85 is at least substantially radial to the axis of the mandrel 18, while the short leg extends approximately 1/8-inch beyond the long leg in the direction of movement of blade element 85 during the wrapping .

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oper~tlon. Tha- th~ l~g of bl-de el~=~nt ~5 coDt~ctlr.l~ the blank 11 h~-8 totnl length o~ ~ppro~1~3at~ly 1/4-lnch In thl~ partlcul~r ~mb~diment.
~1RO 1D thll~ p~st~cular em~odin~nt th~ blada ~ 83 i~ ~ount~d wlth th~ tralllog edg~ ther~ long th~ Or oldi~g ~rlng 38 whll~ the bl~de element BS ~ mounted 11l ~oldlng ~ng 37 ~ltb th~ tralling edgo th~roof off0~t t~ard tb~ l~dlng ~lto of fold~ riDB 37. and the ~old-Ing ~e~ 37 ~nd 38 r~3 mount¢d au~h tbat the ~ngl~ bet~en thc cl~mp 21 ~nd the ~rll~llog edg~ of blad~ el~e~t 85 1~ at least equal to, 1~ ~t sllghtly gre~lter th~n, th~ le betlrecn the cl~lmp 21 ~d the mld-lino of bl~de elelDcnt 83, such that ~h~ ng eago o~ L~ p~d blade ~le-mene 8S i- 8everal d0gre03 ~n ad~ans:~ o~ th~ di~lg ed$e of bl~de ol~
Dlent a3, to thereby csu~e th~ s~d~ lDarg~n o~ bl~ 11 co~tacted b~ blad~
ele~nt 85 to fold In~srd~ under the oppos~a dde ~rgl~ o~ blallk 11 ;~ contncted b~ bl~de ele~ t 83. ~bQ leadlD~ ~d8~ of bl~dQ el~at B5 ~ end~ for~Qrdlr o~ the ~dJac~C le~tiDg ~ of ~EoldlD~ ~lfiS~ 37 to pro~d~ ~os~ e~ b~tw~ ~o~i~g q~ 37 aDI~ ~dSIl~ l~ad 39 ~t th4 . eonell~oioll of the ~r~ppl~g motio~
After th~ co~letioa o th~ llag Dpl#l~lt~ the i~d~ing ~clunlsm for turr~t 17 ~:au~s turret 11 t~ ~ndrcl 18 c~
the n~wly fo~ed tl~b~g 23 o~t of th~ ~idff7~11 wr~pplng st~tIon to~rd th2 botto~ h~atlDg ~t~tion ~md tbe ~arsdYel 18 cs~ ing tho ~ly f~
blsDlc 11 to mova Ol~t of th* ~ltes~sll bl~k r~eeiv~ seatlon to7~srd e~e sldewall bl~k vr~ppiDg otat~ Upon the co~nce~nt o~ th move-t of th~ m~ndrel lB e}~y~g t~e t~blng ~ clllsting s1~ft 49 1~
acti~atcd to C8U8~ ~sapplng ~lngs 37 ~nd 38 to retr~ct frols th~ ~rapped or closed posltlo~, sho~n ln ~IGURl~ 6, to th~ n po~tion, thereby pQr--. mltt~DE~ the ~ndrel 18 carr~lng th~ n~ly ~ k 11 to ~nter th~ sid~
~all bl~ pp~ng ~t~tio~.
Rea~o~a'ble v~r~atlo~s ~nt ~odific~ion~ ~re possible ~l~chin the JCOpO of th~ forego~ tl0C108Ur~, lth~ drawl~g8 ~nd the appeltded :

lot~ ,~319 claims to the invention. While slots 6~ and 67 have been shown in the plate element o~ carriage ~2, th~ carriage 42 can be provided with any suitable means defining the first and second slots 66 and 67, preferably a rigidly fixed part of the carriage 42. While slots 66 and 67 have been illustrated in the presently preferred position of extending along a single straight line perpendicular to the direction of reciprocating motion of carriage 42, the slots 6S and 67 can be positioned along sep-arate lines which intersect the direction of reciprocating motion at angles other than 90. However, it is still desirable that the slots be positioned such that the slide elements have a component of travel perpendicular to the direction of reciprocating motion. If desired, for ease in manufacture, slots 66 and 67 can intersect opening 53 or be in the form of a single slot when opening 53 is not employed or does not intersect the slots. The alignment of slots 66 and 67 along a single straight line perpendicular to the direction of reciprocating motion is particularly advantageous in the machining of the slots in plate ~2.
While the slide elements 69 and 73 have been illustrated as rollers, any - other suitable slide element could be employed. The width of the slide elements is preferably just sufficiently less than the width of the cor-.~
responding slot to permit freedom of movement of the slide element along the length of the slot, while avoiding any significant play of the slide element in a direction transverse to the slotO In a presently preferred embodiment the clearance between the slide elements and the ad~acent ` walls of the slot is approximately 0.002 inch. The movement of thewrapping wings under the sole control of the slide members provides for the relatively smooth operation of the wrapping wings in contacting the blank 11 and wrapping the blank about the mandrel as compared to the ~slapping of the clam shell mechanisms. While the shaft 54 has been illustrated as extending through opening 53 in carriage 42 for com-pactness and minimum length of lever arms o8 and 72, it is possible for ; shaft 54 to be positioned outside of carriage 42 by employing longer .

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~V~ 3~9 lever arms 68 and 72. While sleeve bea~ing 43 has been illustrated on the underside of plate 42 to provide clearance for lever arm 68, both sleeve bearings 43 and 44 can be mounted on the same side oE plate 42 where clearance is not a problem.

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Claims (4)

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

1. Apparatus for wrapping a blank about a mandrel, with the mandrel being in a blank wrapping position, to form a convoluted tubular sidewall, which comprises a mandrel; a clamp-ing means associated with said mandrel to hold an intermediate portion of a blank therebetween; first and second folding wing means; each of said first and second folding wing means having a frame, a wiping blade and means for resiliently mounting the wiping blade in the frame for movement of the blade along a line radial to the longitudinal axis of said mandrel when said man-drel is in the blank wrapping position; said first and second folding wing means being positioned for the wiping blades to con-tact the outer surface of the thus held blank on opposite sides of said clamping means; means for rotating each of said first and second folding wing means about the longitudinal axis of said mandrel in the blank wrapping position at an at least sub-stantially constant distance from the longitudinal axis of said mandrel to wrap the blank about said mandrel with one side mar-gin of said blank overlapping the opposite side margin of said blank; and means for sealing the thus overlapped side margins to thereby form a convoluted tubular sidewall; one of said wiping blades having a generally L-shaped configuration with one leg of the L-shaped wiping blade forming the surface which contacts said blank, said one leg extending forwardly in the direction of movement of said L-shaped wiping blade during the wrapping of said blank about said mandrel to lead the forward edge of the other of said wiper blades to cause the side margin of said blank contacted by said L-shaped wiping blade to fold inwardly under the opposite side margin of said blank contacted by the other of said wiper blades.

2. Apparatus in accordance with claim 1 wherein said one leg of said L-shaped wiping blade extends forwardly past the frame of the folding wing means in which said L-shaped wiping blade is mounted.

3. Apparatus in accordance with claim 2 wherein said L-shaped wiping blade is a unitary blade element having an L-shaped configuration and is mounted on a backup element.

4. Apparatus is accordance with claim 1 wherein said means for rotating comprises a carriage, means for effect-ing forward and retractive motion of said carriage, guide means for supporting said carriage in said guide means in a recipro-cating manner, first and second shafts, said second shaft being a sleeve positioned about and coaxially with said first shaft, said carriage having a first opening therein with said first shaft extending through said first opening, said first opening being sufficiently large in the direction of the reciprocating motion of said carriage to prevent interference between said carriage and said first and second shafts, said carriage having means defining first and second slots therein extending at least generally transversely to said direction of the reciprocating motion, a first slide element in said first slot in operative engagement therewith, means connecting said first slide element to said first shaft for rotating said first shaft responsive to movement of said first slide element, and a second slide element operatively positioned in said second slot in operative engage-ment therewith, and means connecting said second slide element to said second shaft for rotating said second shaft responsive to movement of said slide element.