CA1192718A - Method and apparatus for making billowed filling elements for packaging and elements made thereby - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE

A plastified mass of thermoplastic material con-taining an expanding agent is extruded and sliced into pieces by shaped cutting edges to produce--on expanding--elements which are shaped in a billowed manner or a double-bubble manner.
The billowed elements have an inturned peripheral edge which prevents nesting and interlocking together when used in a ship-ping container. Similarly, the double bubble elements preclude nesting and interlocking.

Description

A MTHOD AN~ APPARATUS ~OR MAKING BILL()~`JED FILLING
ELE'i'~ENTS EOR PACXAGING AND ELE~IE~TS '~DE T~IEREBY

This inven-tion relates to loose fill packaging elements and to a method and apparatus for making filling elements for loose fill packaging.
As is known, various types of loose fill packing elements have been used to insulate articles in shipping con-tainers against damage from vibrationand impact forces during shlpment of the articles. In many cases, in order to avoid the disadvantages of pac;:aging materials such as sawdust, popcorn, excelsior and the like, resort has been made to the use of resilient thermoplastic elemerts. These elements have been produced in various shapes in order to provide a cushioning effect for -the arti--les being shipped, and a nesting or inter-locking arrangment which forestalls a shifting or migration of the cushioned articles within the shipping container in the course of the shipment of the article.
Heretofore, in order to manufacture the resilient thermoplastic packaging elements, it has been known to extrude a heat-plastified mass of thermoplastic material containing an expanding agellt through an orifice to form a rod which is then severed at longitudinal increments into discrete elements. In some cases, it has been known to cool -the rod af-ter extrusion and prior to cutting. In such cases, the subsequently cut elements are of an expanclable nacure. That is, the element, can '~e subjected to heat at a ]ater time to cause an ~:parl-ion of the elements due to the expandiny agent incorporated therLin.
Such foamable elements can be shipped in bu]k to the ultimate user and thereafter expanded under heat into a foamed useable state. Where the shapes of the elements permit, the foamed elements can then be poured from hoppers or the like into individual shipping containers. In other cases, the extruded rod can be cut prior to cooling so that discrete elements severed from the rod can be individually cooled into an expandable state.
Generally, the elements which have been produced by an extrusion of a thermoplastic material through an orifice of a die and a severing of a resultant rod have had a uniform thickness. That is, each element has had a constant dimension in the direction of the extrusion and a substantially regular shape. Because of the regular shape, the thermoplastic elements have often tended to pack together within a shipping container such that the bulk weight of the elements in the container is relatively high. Accordingly, attempts have been made to impart shapes to the elemen,s which tend to createlarge empty spaces among the elements in a container and thereby reduce the bulk weight of the packaging material. These attempts, however, have generally been directed towards the providing of a specific type of cross-section to produce an irregular shape. For example, it has been known to extrude a foamable thermoplastic material through an orifice to produce a rod-like length having an irregular cross-section, for e~;am~le or a so,.ewhat triancu'-~r shape, C-shape or E_5ha2G
and to thereafter sever the rod into segment.,. ~t has al.s(>
been known to extrude the thermoplastic ma-terial to form a cylindrical rod -~hich is subsequently sliced into thin pieces which, after being heat-expanded, derorm into a somewha-t partly spherical shape. Other techniques have also been known, such as described in U.S. Patent 4,104,440, for making packaging particles with a normally curved configuration having two curved substantially co-extensive surfaces with one surface being con-cave and comprised of a substantially unfoamed skin while theremainder of the particle is foamed. Also, as described in U.S.
Patent 3,961,000, it has been known to extrude a plastic compo-sition through an orifice such that the protruding mass is bounded by a convex surface that extends from the perimeter of the orifice in a partially spherical sweep, to cut off the pro-truding mass along a path which is substantially straight or linear as compared to the convex surface, and to expand and cool the resultant pieces to form bodies having hollow subs-tantially hemispherical configurations. These bodies are formed so as to either nest or interlock with each other in order to prevent migration.
In essence ! the previously known techniques have relied upon the severing of an extruded material in a straight line manner; that is, the severing of the extruded rod has been carried out by using a straight edged blade which cuts in a direction perpendicular to the longitudinal axis of the extruded rod. As a result, the resulting packaging elements, after foaming, are ~enerally of regular shape con~orming to the 7~

unexpanded state. While such elements may be free-flowing when poured into a shipping container from a supply nozzle, the elements tend to interlock in use within the shipping container and thus occupy less space (i.e. taking on a greater bulk density) than necessary in shipping containers.
Accordingly, :it is an object of the :invention to provide a rnethod for making expanclable filling elements which are capable of deforming in a three dimensional manner upon foaming.
It is another object of the invention to provide a simple means of forming discrete foamable thermoplastic elements which are capable of foaming into regular non-interlocking shapes.
It is another object of the invention to provide a simple apparatus for making filling elements of regular three dimensional shapes.
It is another object of the invention to provide loose fill packing elements of three dimensional billowed shapes.
It is another object of the invention to reduce the bulk density oi a loose fill packaging material to a mini , .
In accorclance with the present invention, there is provided in an apparatus for making filling elements for packaging, the combination comprising an extruder for extruding a heat-plastified mass of theroplastic material con-taining an expanding agent, said extruder having a die at one end, said die having at least one orifice therein for extrusion of the heat-plastified mass therethrough along a longitudinal axis; and a rotary cutter having at least one cutting blade having a non-linear cutting edge for cutting the mass extruded through said orifice, said cutter being disposed on an axis of rotation perpendicular to said longitlldinal axis and in spaced facing relation to said die to move said non-linear edge of said blade through an arcuate path -to cut individual pieces from the extruded mass.

:1 ~9~71~3 In accordance with another aspect of the invention, there is provided an apparatus for making filling elements for packaging, said apparatus comprising an extruder for extruding a heat-plastified mass of therMoplastic material containing an expanding agent, said extruder having a die at one end with at least one orifice therein for extrusion of the heat-plastified mass therethrough; and a rotary cutter having a plurality of cutting blades thereon for ~ c~c~
sequentially cutting the mass ext~uded throughlsaid orifice, said cutter being disposed in spaced facing relation to said die to move each blade through an arcuate path to cut pieces from the extruded mass, at least one of said blades having a non-linear cutting edge for cutting through the extruded mass.
Briefly, the invention is directed to a method and apparatus for making expandable filling elements for packaging. In addition, the invention is directed to a loose fill packing element of expandable thermoplastic material and a loose fill packaging material made of such elements.
In accordance with the method, a heat-plastified mass of thermo-plastic material containing an expanding agent is extruded through an orifice having a predetermined cross-sectional shape along a longitudinal axis. The extruded mass is - ~a -3~t~

then cut cr sli_ed transversel~ to the axis adjacent to the orifice ar alonc a non-1inQ~r ?ath ac^oss the extru(1ed ma.;s to form a lurality of expandable pieces each of which has a recessed Eront face. The cut pieces are then cooled to prevent suDstan~ial expansion. The sliciny of the extruded mass occurs at intervals such that each piece is of a relatively thin thic}--ness which is greater than a transverse width of â rectilinear section of the piece. For example, slicing occurs at intervals of 0.25 to 0.375 inches.
In order to use the foamable pieces for packaging pur-poses, a mass of the pieces is heated to expand each piece.
The heating results in each piece deforming inwardly of itself along the periphery thereof.
The orifice through which the plastified mass is extruded may be of any suitable shape. For example, the orifice may have a rectangular cross-sectional shape such that each cut piece has a like rectangular cross-sectional shape. The orifice may also be of another cross-sectional shape such as oval, circular, fluted-circular, tri-lobal and triangular. Likewise, the resultant cut pieces may have similar cross-sectionalshapes.
The cutting of the extruded mass may also be accom-plished along different types of non-linear paths. For example, the non-linear cutting path may be V-shaped, or of a semi-circular shape, a zig-zag shape, or a shape having a plurality of contiguous perpendicularlydisposed sections.
In one embodiment, the plastified mass is extruded through an orifice which is disposed in a V-shaped groove of a die and which is of rectanyular cross-sectional shape with a ~2'~

hei,ht ~wice ~n-~ width thereof, while a V-sha?ed cu~ is made in the forward end of the e~'cruded mass by a cutting blade ~,/ith a V-sha?ed cutting edge. The pieces which are cut aresubce~luGntly heatecl to expa~d and deform into shell-li};e bodles. In one ca~-e, the V-shap-d cut is made by a blade which has a cutting edge~ith an angle less than -the angle of the V-shaped qroove of the die.
This produces an elongated shell-like body which tends to be thicker from the center to the outward sides. Upon expanding under heat, the difference in thickness causes the expanding l~ body to bubble or billow while expandiny the side outwardly such that the center buckles at the groove formed by the blade. The resulting expanded body is characterized in having a billo-.ed shape with a free inturned peripheral edge defining an open mouth of lesser extent than the surrounding portions of thebody.
In another case, the cutting edge of the blade may define an angle equal to or more than the angle of the V-shaped groove of the die. In this case, a body is produced which has a slight gouge or crease running longitudinally of the shell-like body at the bottom of the recess of the body. Upon expanding under heat, the longitudinal crease tends to buckle forwardly while the body billows so that a longitudinal rib forms between two bubbled or billowed sections. The resulting expanded body is characterized in having a billowed shape with two pockets separated by a central rib, i.e., a double bubble.
The apparatus of the invention includes an extruder having a die with at least one orifice for the extrusion of the heat-plastified mass and a rotary cutter with a-t least one cutting blade having a non-linear cutting eclge for cutting the extruded ~ass. The cutter is disposec' in spaced ~acir3 ~elation to the die and moves the cut.ing edcJe of the ;olade .hrou~l an arcuate pa-th to cut pieces from ~he extru~'ed mass. ~or exar~r,le, the arcuate path of the blade of the cutter may ha~1e a four inch radius while the outermcst point of the ~u.~ing edge is spaced from the die face at a listance of approximately 0.005 inches.
With each pass of a blade, the extruded mass is sliced at inter-vals of 0.25 to 0.375 inches. In this regard, it is to be noted that the ~ass may extrude a greater distance bet~Jeen cuts. How-ever, the speed of the cutter is synchronized with the output ofthe extruder to obtain a nominal thickness of approximately 1/64 to 1/4 inches in the direction of extrusion.
The rotary cutter may utilize blades with cutting edges of various shapes. For example, the cuttiny edges may be pointed tips of triangular shapes, edges of V-shape, semi-circular shape, zig-zag shape or of a shape having a plurality of contiguous per-pendicularly disposed sections. Also, the cutter may be provided with blades having different cutting edges. For example, the cutter may be constructed with a pair of diametrically opposed

2~ blades with one of the blades having a non-linear cutting edge while the other has a linear cutting edge. A cutter of this type produces pieces with two different types of cut shapes.
Specifically, each piece has a substantially flat end caused by the linear cutting edge while the opposite end is of a non-linear shape corresponding either to the outside or to the inside of the cutting ecge of the other blade.
In addition, the apparatus includes a cooling means for cooling the cut pieces in order to prevent substantial expansion ~:3.9~7~L~

of the piecQs. Thls cooling means may be in the form oE a wat~V
tank disposed helow the extrucler clie to receive se~/tred ~,ie(e-which drop under gravity.
Still further, the apparatus may be provide-3 with a heati.lg means for subseauent heatingiof the severed pieces in order to expand each piece of the mass into a fully expanded or partially expanded state.
In a case where the heat-plastified mass is extruded through an orifice of rectangular cross-section having a height twice the width thereof and is cut with a blade having a V-shaped cutting edge, the expandable elements have an elongated shell-like body with a generally smooth recessed inner surface and a contorted ou-ter surface. When these expandable elements are subsequently heated and expanded, each element has a shell-like body defining a hollow billowed shape with a free inturned peri-pheral edge defining an open mouth of lesser extent than the surrounding portions of the body. A loose fill packing material comprised of a plurality of these expanded elements is character-ized by having the elements disposed in contiguous non-nesting non-interlocking relation, i.e., in an abutting relation. As such, each element occupies a maximum volume, thus reducing the overall bulk density of the packing material, for example, within a shipping container. For example, the bulk. density of the pack-ing material is about 0.25 pounds per cubic foot.
In a case where the orifice is in a V-shaped recess of a die and the blade is spaced closer to the die wi-th a V-shaped cutting edge equal to or more than the angle of the die recess, an expandable body is obtained which gives a double bubble shape upon expanding. As aDove, a loose rill pac~ing materi~l co~-prised of these expanded elements has the elements in a~ tted non-nesting non-interlocking relation.
It is to be noted tha-t the ~illowed configuration o the expanded elements adds to the resiliency of the eie.~,erlts oy imparting a spring-like characteristic. Fur-ther, since the mouths of eleMents are smaller than the surrounding contour, nesting of the elements is substantially eliminated.
It has ~een found that the cuttin~ of the extruding plastified mass into pieces having end walls of different shapes influences the direction in which expansion occurs when the pieces are expanded. That is, where the front "wall" of each piece is cut on a non-linear path to have a recessed front wall while the rear "wall" is cut to have a complementary shape or a flat shape, the elements have a tendency of expanding in the direction of the rear wall. Thus, if the basic cross-sectional shape is cylindrical, the expanding elements tend to expand in the manner of a balloon. ~here the cut cross-sectional shape is rectangular, the expanded state tends to be billowed. In any event, the expandable piece tends to expand at a lesser rate radially than axial]y so that as the piece expands toward the rear wall, the periphery tends to move relatively radially in-wardly. The differential expansion is believed to occur since a tough skin is formed about the periphery of the cut pieces during extrusion while the ends, i.e., the front wall and rear wall are exposed with an open cell structure. Thus, expansion occurs in the direction of least resistance.
~here both end walls of the extruding plastified mass _9_ 7~

are C'lt /ith tn~ sa~e tv?e of cuc-i~c~, 2dae, the cut pi~ces .h~vfe a substclntial~ uni~orm thic};ness. In the case where~ tl~le ~xtr~d-ing mass is suc essi~Jely cut wi.h cuttlr.g ec3ges of alternatinc~
shapes, two ~pes of pieces result.
These and other objects and advantages of the invention will hecome more apparent from the following detailed description and appended clairns taken in conjunction with the accompanying drawings in which:
Fig. 1 illustrates a perspective view of an apparatus for making filling elements in accordance with the invention;
Fig. 2 illustrates an enlarged exaggerated view of a loose fill packing element in an expandable state and an expanded state as produced by the apparatus of Fig. 1;
Fig. 3 illustrates a perspective view of a rotary cut-ter having a modified cutting blade in accordance with the invention;
Fig. 4 illustrates an apparatus havin~ a further modi~
fied cutter in accordance with the invention;
Fig. 5 illustrates an enlarged exaggerated view of a modified packing element in an expandable state and an expanded state as produced by tlle cutter of Fig. 4;
Fig. 6 illustrates an enlarged exaggerated view of a further modiEied packing element in an expandable state and an expanded state;
Figs. 7 to 11 illustrate various orifice shapes for the die of the apparatus according to the invention;
Fig~ 12 illustrates a plan view of an extrudate which is cut in accordance with a cutter having different c~tting --lq--blades in accordar.ce ~ith ~he in~ention;
Fig. 13 i1lustra~es a ~Jie~,/ similar to ~ig. 12 of an e;t-udate cut ~ith a modi ied cut~er having di. erent typ-s of cutting blades in accordance with the invention;
~ ig. 14 illustrates a fragmentary view of a furthcr mod fied apparatus for making filling elements of a double bubble type in accordance with the invention;
Fig. 15 illustrates a perspective view of an expanded double bubble type of filling element in accordance with the invention;
Fig. 16 illustrates an end view of the filling element of Fig. 15; and Fig. 17 illustrates a view taken on line 17-17 of Fig.
15.
Referring to Fig. 1, the apparatus employs an extruder of generall- known structure for extruding a heat-plastified mass of thermoplastic material containing an expanding agent. To this end, the extruder includes a die 10 at one end which is con-structed in block-like manner. The die 10 has a plurality of cylindrical plugs 11 mounted in a flat end face 12. Each plug 11 has an orifice or bore 13 of rectangular cross-section with a height greater than the width, for example with a height 1 1/2 times the width. As shown, each plug 11 has a V-shaped vertical groove 14 coincident with the orifice 13 forming an angle of approxlmately 90 with a depth of e.g. approximately 3/16 lnches and a width of approximately 3/16 inches, while the end face 12 of the die 10 has similar curvilinear grooves 15 of V-shaped cross-section forming continuations of the groove 1~ in each _ 1 , 'f'~ll8 plug 11. In addi ion, each plug 11 has two flat surf2ces 16, each disposed on an opposi~e sidc of 'ne (1roov? 1~ to for~ a CortinUatlOn of the flat face 12 of the die 10. r3urinc oper~tion of the ext~u~er, an e~trudate 17 is e~truded througrl each o' the orifices 13. The ext-udate 17 thus tal~es on the same cross~
sectional shape as the res?ective orifice 13.
In addition, the app~ratus includes a rotary c tter 18 whichis mounted on an axis of ro-tation perpendicular to the longi-tudinal axes along which the e~trudate 17 is extruded from the die 10. The cutter 18 includes a shaft 19, a cylindrical mount-ing block ~0 and a plurality, e.g. two, eutting bladcs 21. Each blade 21 is mounted in a radial groove 22 of the block 20 and is secured in place via scre-s 23 which pass throush suitable bores (not shown) in the bloc'~ 20 perpendicularl~ o the groove 22.
Each blace 21 has an elongated base 24 from ;hich a plurality of cuttinc3 edses or points 25 project. Each point 25 has a pointed tip, e.g. of a tri2nsular shape, wherein the for-ward face 26 is of lar~er di~cnsion than thc rear face 27 such th~t a char~bcr 28 is formed about the edge of the tip. The pointed tips arc spaccd from the base ~ so as to provide a clear-ancc to avoid cloc;sing during opcration. Furt'lcr, each pointed tip may form an angle of from 20 to 30 ~ith a leng-~h of about 1/~ inch.
The cuttcr 18 is disposeà on an a~:is of rotation wnich is perpcndicular to and co-planar ~ith thc a~:cs of e~:trusion of ~ac'l orificc 13. Thc cut~:cr 18 rotates so as to move cactl cuttinc poir,t 2~ of a blac'e 21 throuc3h an arcuatc pa h to cut: V-sh.3pcd pieccs 29 from tnc e::t-ud~tc 17 ei:truced from eacl orlfice 13.

In this cas~, each ~lacle point 25 forms an an~le 1CSS than the ansle o, the associated groove 1~1 an~l is sp~ced from th~- ~froovc 14 of a dis'.~nce of appro;ir~ately .005 incncs.
The cutter 18 is disnosc~l such that the b],ac3ex 21 cut the extruded mass 17 in a transverse direction adjacent each ori-fice 13 and alon~ a non-linear path across thc extruded mass to form e~;pandable pieces 29 of thermoplastic material. The cutting or slicing of the extrudate 17 is similar to a peeling action in whieh the pointed edges 25 peel through the extrudate to peel off the pieces 29. As indieated, eaeh eutting point 25 is aligned with a respective orifice 13 to move through a curvilinear groove 15 in the die 10~ Hence, each cut piece 29, as shown in ~ig. 2, has a recessed front wall (i.e. of substantially V-shape) which corresr~onds to the shape of the outside surfacc of a cuttinq point 25 and a rear wall of complcmentary shape to the front wall.
The rotary cutter 21 is timcd to rotate relative to the spced of e;trusion such that the individual pieccs 29 have a thic,;ness of, for e~ar,tple, appro~;imatcly 1/4 inch to appro:;i-mate],y l/G4 inch.
The picces 29 arc cooled irn~,ediatcly after cutting so as to retain an e~pandable nature. To this end, the pieees 29 may be allowed to fall under gravit~ dircc~ly into a cooling trougll o' water, or the picccs r-,ay be other~.:ise coolecl arter eutting.
Each cooled picce 29 is characteri~ed by having a relatively tOU5}1 Sr:ill about thc pcriphery whilc the front and rear walls have a lcss d~r.,e sur-acc.
~ftcr cooling, thc individual picccs r~ay ~c hcated, --1,-for e:~amDle, bv using stea~, in order to e~.pand -the pieces to a larger size. During heating, since the 2erim2ter of th~ pieces ten~s to resis~ expansion, and since the front face of e~ach picce is recessed towards its re~rr face, e~:~ansioll tak~es ~la~e pri-maril~ in a rearward direction. Thus, eac~l "iece de'orms inwar of itsel~ along the periphery in-to a shcll-like boAy defininc; a billo~cd shape with a free inturned peripheral edge cle~inincj an open mouth of lesser extent than the surroundinc3 portions of the body.
Prior to expansion, it has been found th2t the expand-able state of the piece 29 has an elonsated shell-like body with a generally smooth recessed inner surface and a slightly con-torted outer surface. This contorted surfacc appears to be caused b~ a small differential e;~pansion of the cut pieccs to com21ete coolinq.
Because of the billo::ed sh~ c of thc expan~lcd elemcnts, the elements can be s2aced ~rom eac'l othcr in a mutually con-tiguous abutting relationship without nesting or interloc~ing with each other. As such, the ex~anded elements can occupy a greater volume, for example, within a ship"lna containcr. This in turn reduces the ovcrall bul'-~ dcnsit, of a mass of the ele-ments ~ithin thc ship?ing containcr, anc' thus reduccs the trans-portation costs of a packaged article.
The billo.;ed shape of thc e:;panclcci. elements also aclc's to the resiliency of the elements relative to each ot~er. That S, cach elemcnt tends to act as a sDring.
The billo:ec' elellcnts m~. Lc voure(l ~rom a hoi~per dircctly into a ship2inc; containcr. ~o this cnd, the mouth of 1. ~ZL 9 ~2 r;~ 3 ~

each respecti~v~e elenent is smaller than it~ ~;ene-ral cor~ol~r ~3 that adjacent element.~ do not lnterloc!~ or nest ~ith one arot~h~ r~
In order to ~ake an ex2andable fil]ina elemenL, a p1astified mass Or .her;nor~ stic materia] containin(7 an c::~a.nd-ing ac~ent is e~truded throuc;ll each orifice of the die a]on~ a longitudinal axis toward the cutter. As the material e trudes, the cutter repeatedly cuts the extruding material at each orifice in a direction transverse to the longitudinal axis and along a non-linear path across the extruded mass in order to form a plu-ralit~ of e~pandable pieces. ~ach piece has a thickness which isrelativel~ thin. Each cut piece is then cooled, for e.Yample, b~;
dro?ping under gravity into a water bath (not shown) so as to prevent substantial e~pansion, or cooled by air.
After cooling, a ~lass of thc picces can bc heatcd to e~pand each piecc for use as a pac'~-aging material. Such e:;pan-sion may be provided after shipment of the e~pandahle pieces to an ultimatc uscr. The pieces may al.ernatively be slic~htl~ e:~-pan~ed un~cr lleat ~y their manuracturer and be shippcd in this condition to an ultimatc uscr for further e~:pansion. During e~pansion, eac'l ?iece àe orr~s inwarc'ly of itself alorg the peri-phery relati~;e to the a::ial e:~?ansion of the piece.
Rcferri;ls to Fis. 3, whcrcin li`:c reference characters indicate li~c parts as abovc, the cutte- may utilizc a blace 40 of di_ferent cons~ruction from that dcscribed abo~e. As indi-cated, each blade 40 is of a U-shape with legs 41 disposed in suitablc matins rccesses 42 in a rotar,~ mounting bloc: 43 and cac~ le~ 11 has a suitablc borc (:,c,t ~;howo) Lc r rcc,e~ r~3 a screw 44. In addition, cach cuttir.q bladc 40 has a ~)lurality of non-linear cutti.-(3 edges 45 for cuttinc the mass (e::trudat~ 17) e~trude~ .h-ough the respective ori~ices 13. As sho,/n, e3~.,h cuttins edae 45 is of V-shape sized to move throllgh cl respe-ctive groove 15 of the die 10 and is di~ected outiardli~ of the cut~rr 14.
The pieces which are cu~ Erom the extrudate 17 b~ the blade 40 are of similar sha2e to -those as shol.Jn in Fis. 2.
Referring to Fig. 4, wherein like reference characters indieate like parts as above, the blade 40 may alternatively be formed with eutting edges 45' which are of semi-circular shape.
In this case, the pieces 46 (see Fig. 5) t~hich are cut from the extrudate have a recessed front face 47 of semi-circular shape and a rear face 48 of similar semi-circular shape. ~hen expanded, as shown in Fig. 5, the pieces tend to ta}:e on a bowed sha2e t.~ith a substântiâlly C-shaped cross-section.
Alternatively, the cutting blade ~ay also have cutting edges which are of a zig-za~ shape so as to produce pieces 49 from the extrudate which have recessed front and rear faces 50, 51, respeetively. Sueh pieces, t~hen expanded, tend to form pieees Wi~}l a star-li'e eross-see~ion.
Referring to Figs. 7 to ll, the orifice through ~hich thc e~:trudate is extruc-lcd may be other than of rectangular sha2e.
For example, the orifiee may be of circular cross-sec~ion so as to produce a piece 52 having a similar cross-scc~ion (see Fig. 7).
Also, the orifice may be of oval, fluted-circular, tri-lo'.~ular or triancular shal)e so as to produce 2ieces ~3, 54, 55, 56 of corres?orcling cross-section.l~ sha,~ as srlo.:n in ~`igs. ~ o 11, res~ec~ivelv.

--1~--Referrin~ to Fiys. 12 an~i 13, the cuttinq blades (not shown) for a cutter may be made ~;ith ciif~erent cutting ed.;~s.
For e~:ample, a cutt~ar may be provided with a cul;tincl b]~lcie as shown in Ficj. 3 and a cutting blade havi,l~ a straic3ht edge~. In this case, the cutter cuts pieces ln yalrs with alternatincJ
shapes. Specifical]y, as shown in ~ig. 14, the first piece of one pair has a recessed front face conforming to the ncn-linear eutting edge and a flat rear face formecl by the straight cutting edge. The second piece of the pair has a flat front face con-forming to the straight eutting edge and a pointed rear face which is of a shape eorresponding to the inside edge of the non-linear cutting edge~.
As shown in Fig. 13, if a blade having a zig-zag shaped cutting edse is used ~ith a blacle ha~ing a straight cutting edgc, the resulting pieees have corrcsponding fron~ and rear faces, as indicate_. That is, the front face of a first plece is re-cesscd by a plurality of contiguous perpendicularly disposed sections while the rear face is flat. The sccond piece of each pair has a flat front faec and a rear face ~hic~ has a projection forr~cd by a plurality of eontiguous perpendicularly disposed surfaces.
It is to be noteci that the various ?ieccs :;illCil are eut in thc ~anncr sho:;n in Fiss. 12 and 13 ~:ith fla~ .ron~ faccs tclld to e-:pand tohares the rcar surfacc duc to the lar~gcr arca of the rcar surfaces.
Re'errins to ~ig. l~, whcrcin li}:c charactcrs indica~c li~e parts as abo~e, thc~ cutter l'i, hc~s a pL~ir of bl3cles 21' (onl,~ onc of :Jhich is sho:n) ~ach o' WhiCil il.~s CUttinf~ pO~ S

t7~L~

2j' formed at an ancJle~ equal to or grea~er thall the arc~1e of the groo~e 14. For example, the angle of the cuttin~3 ?oints 2,' is approximately 100~ while the width is appro~irnatcl~ 1/4 inch.
During operat:ion, with each ~lade point 25' spaced from a groo-e 14 a distance of approximately .005 inch, the pieces 57 cut and cooled from the extrudate 17 have a scored line or crease down the middle of the front face. Thus, upon heating, the pieces 57 tend to expand less aloncJ the crease than in the areas adjacent the crease. As a result, as indicated in Figs. 15 and 16, a rib 58 tends to form at the crease within the e.~panding piece while a double bubblc is formed. The resulting e~panded element 59 is thus characterized in having a double bub-ble shape (see Figs. 15 and 17). This double bubble shape is similar in front view to the billowed shape of the pieces 29 dcscribed abovc ~lith respect to Fig. 2 with thc addition of a raised central rib 58 along a line corresponding to the crcase in the une~:panded state. This formed rib serves to reinforcc the e~pandcd piece 59. From thc rear, the double bu~blc shape shows t~o somcwhat hcmis~hcrical shapes 60, 61 (i.e. bubbles) merging to.,e~tilcr along a central longitudinal depression G2 which deprcs-sion is t~c ~acksidc o~ thc ccn~ral rib 58 at the fro.~t.
The heat at the die 10 ma~ be adjusted, e.s. betwcen 180 to 300F, to cause various effects in thc scvercc3 picccs.
For c:~:ample, with a high temperaturc, each scvcrcd piccc curls to a closcd s!cll while, :ith a lo:: tcrlpcrature, cac!l piccc tencs to form a ccm?lctel~ open shcll. Thc dou!~lc ~u!;~le cffect occurs at a tcm.~cratulc (J~ a.)out 200 ~.`.
The shai~c of thc scverc(3 pi cc~ is al_o ir-f'ucnccd 'a~

7~

the ~hic;;ness vf the ~iece relative to the widti~ o th~ ?i~
That l5, if the piece is too thic~, the "V" cut or cr?ase ma~
not create an~ dc)uble bubble e'fect. If the piece is too thin, the piece may well break or curl upo~ itsel.. 'rhus, the thic!~.-lle.,~ is ~ O 11 ~ _ C ~ e ~ c t!r ~ t~ur'.-~ f~o~ t~.~-die 10 and th_ speed of the cutter 18. Typicall~, the cutter 12 ma~ ro'ate at 1000 RP-~.
The shape of each piece is also in direct relation to the amount of blowing agent dispersed throught the e~trudate.
If the amount of blowing agent is too low, sufficiènt e~pansion will not occur. Thus, the shape will be similar to the immedi-ate shape that occurs upon leaving the cutter lS. If thc amount of blowing asent is too high, the severed piece may be torn and rar~3scd as the plastic w;ll not be able to hold thc c~ccssivc qas and rupturing will occur causing the piece to shrcd. Nucleators, as arc~ }~nown, may also be used to rJiVC a larr.3cr or smallcr cell structure.

Claims (8)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. In an apparatus for making filling elements for packaging, the combination comprising an extruder for extruding a heat-plastified mass of thermoplastic material containing an expanding agent, said extruder having a die at one end, said die having at least one orifice therein for extrusion of the heat-plastified mass therethrough along a longitudinal axis; and a rotary cutter having at least one cutting blade having a non-linear cutting edge for cutting the mass extruded through said orifice, said cutter being disposed on an axis of rotation perpendicular to said longitudinal axis and in spaced facing relation to said die to move said non-linear edge of said blade through an arcuate path to cut individual pieces from the extruded mass.

2. The combination as set forth in claim 1 wherein said die has a plurality of orifices, each said orifice having a rectangular cross-sectional shape with a height twice the width thereof and each said blade extends across said orifices with a plurality of V-shaped cutting edges, each said edge being aligned with a respective orifice to cut a mass extruded therefrom.

3. The combination as set forth in claim 2 where each die has a plug defining a respective orifice, each said plug having a V-shaped groove coincident with a respective orifice and each V-shaped cutting edge forms an angle less than the angle of said respective groove.

4. The combination as set forth in claim 2 where each die has a plug defining a respective orifice, each said plug having a V-shaped groove coincident with a respective orifice and each V-shaped cutting edge forms an angle at least equal to the angle of said respective groove.

5. An apparatus for making filling elements for packaging, said apparatus comprising an extruder for extruding a heat-plastified mass of thermoplastic material containing an expanding agent, said extruder having a die at one end with at least one orifice therein for extrusion of the heat-plastified mass therethrough; and a rotary cutter having a plurality of cutting blades thereon for sequentially cutting the mass extruded through each said orifice, said cutter being disposed in spaced facing relation to said die to move each blade through an arcuate path to cut pieces from the extruded mass, at least one of said blades having a non-linear cutting edge for cutting through the extruded mass.

6. An apparatus as set forth in claim 5 wherein said cutter has a pair of diametrically opposed blades thereon, one of said blades having said non-linear cutting edge thereon and the other of said blades having a linear cutting edge thereon for cutting through the extruded mass.

7. The combination as set forth in claim 5 wherein said die has a plurality of plugs therein, each said plug defining a respective orifice and having a V-shaped groove coincident with a respective orifice and wherein said blade has a plurality of cutting points thereon, each said point having a tip of triangular shape for passage through a respective groove of a respective plug.

8. The combination as set forth in claim 7, wherein each tip forms an angle of from 20° to 30°.