AU626833B2 - Blown plastic container - Google Patents

Description

rI OPI DATE 06/09/89 AOJP DATE 05/10/89 APPLN. ID 30481 89 PCT NUMBER PCT/US89/00455 TREATY (PCT) INTER A.AT (51) International Patent Classification 4 1/02, B29C 49/10 (11) International Publication Number: WO 89/ 07554 Al (43) International Publication Date: 24 August 1989 (24.08.89) (21) International Application Number: PCT/US89/00455 (22) International Filing Date: 6 February 1989 (06.02.89) D iatr ta AT rop patent), AU, BB, BE rop~mp l3B La.CI-I (European patent), E ea ateD I FR (European patent), GB (European patent), HU, IT (European patent), JP, KP, KR, LK, LU (Euronean patent), MC, MG, MW, NL (European patent), NO, RO, SD, SE (European patent), SU.

Published With international search report.

(31) Priority Application Number: 157,449 (32) Priority Date: (33) Priority Country: 19 February 1988 (19.02.88) (71) Applicant: BROADWAY COMPANIES, INC. [US/ US]; 35 E. First Street, Dayton, OH 45402 (US).

(72) Inventors: BARTLEY, Harold, D. 3920 Monterey Avenue, Springfield, OH 45500 GAISER, William, R, 6124 Singletree Lane, Dayton, OH 45400

(US).

(74) Agents: HENDERSON, Gilbert, N. et al.; Biebel, French Nauman, 2500 Kettering Tower, Dayton, OH 45423 (US).

(54) Title: BLOWN PLASTIC CONTAINER (57) Abstract A bottle (20) useful for containing a carbonated beverage is produced from a ptrison or preform (30) by a blow.

molding method and apparatus so that an annular single thickness depending skirt (28) is formed integrally with the bottle bottom (25) providing a self-standing support for the bottle WO 89/07554 PCT/US89/0(455 BLOWN PLASTIC CONTAINER Background of the Invention This invention relates to &aa g blown oute exc-V u 'i eplastic containers. It has particular relation to pressure resistant bottles such as used for carbonated beverages, or the like, formed of bi-axially molecularly oriented polyethylene terephthalate. However, the principles of the invention may be applied to non-pressure containers, such as for wine, water, or the like, and the principles further are not intended to be limited to bottles formed of polyethylene terephthalate (PET), although the use of such material is preferred.

Blown pressure vessels in the form of plastic bottles formed of PET material have come into general use as disposable containers for carbonated beverages. In order to obtain the drsired bi-axial orientation and to provide the preferred shape as a pressure vessel, such bottles have commonly been made with rounded or semi-spherical bottoms.

In order to support such bottles in an upright position for filing, shelving and the like, auxiliary base cups, usually formed of polyethylene or polypropylene, assembled on the bottle after blowing, have come into widespread usage, as shown for example in U. S. Patents of Chang, Nos. 4,436,216 issued March 13, 1984 and 4,438,856 issued March 27, 1984.

The industry has recognized the desirability of eliminating such base cups due, to the additional expense and inconvenience involved. The additional expense includes not only the cost of the cups themselves, but the cost and maintenance of the attendant separate lines of equipment to produce and handle the cups, and to assemble and glue or weld the same over the bottoms of the bottles. The recycling of

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WO 89/07554 PCT/US89/00455 -2such bottles also presents special problems due to the necessity for removing the base cups to separate the material of the base cups from the material of the bottles themselves.

Various attempts have been made to produce bottles formed of bi-axially oriented plastic material, such as PET, which are free standing on the bottom, using only plastic material which is integral with the bottle itself. Thus, carbonated beverage bottles have been proposed with i::0 ""hampaign" bottoms such as in the U. S. Patents of Aoki, 4,465,199 issued August 14, 1984 and Gittner et al, 4,177,239 issued December 4, 1979, in which the bottom end wall is formed with an inwardly convex surface. The pressure within the bottle tends to cause the bottom to reverse or bulge out, and this must be resisted by adding material to the inwardly directed convex curve or fold forming the champaign bottom.

Further, it is difficult, if not impossible, to achieve the desired bi-axial orientation in the bottom material itself, for optimum strength and stress crack resistance.

201 Carbonated beverage bottles are also being made with a bottom in which pentaloid leg portions are formed in the'bottom wall, which partially project outwardly, to form support or locating feet, as shown in U. S. Patent No.

33,598,270 and U. S. Patent No. 4,518,558 issued May 21, 1985 to Anway et al. While carbonated beverage bottles having such pentaloid legs have been successful, they are subject to stress cracking, and further do not provide an annularly unifirm support as to permit the bottle always to stand upright on a wire shelf.

Annularly continuous integral base supports have been suggested in the U. S. patents of Uhlig, 3,843,005 and 3,949,034. These supports are in the form of double-walled i i 3 depending skirts which are pinched off, in the blow-molding process, from the material making up the bottom wall of the parison or preform, and are pressure molded into a skirt of ring shaLe during the blowing step. While such concept provides a useful and continuous support from a mechanical point of view, it severely reduces the pressure strength of the container as a pressure vessel and impairs the integrity of the vessel. This is particularly true when PET material is used, since it does not weld readily to itself, and a low or weak molecular bond is formed between the adjacent layers making up the skirt. Accordingly, the strength of the bottom is dependent primarily upon the mechanical strength of the f rather than the substantially higher tensile strength of the material forming the bi-axially oriented container wall.

Summary of the Invention According to the present invention there is provided a blow-moulded bottle formed from a preform of PET material fo: containing a carbonated beverage, the oblow-moulded bottle comprising: a tubular body having a longitudinal centre axis, •ego ,a neck connected to a first end of the tubular body, S" a curved bottom connected to a second end of the tubular body, and a bi-axially stretched single thickness annular depending skirt formed integrally with the curved bottom, wherein the skirt i. positioned radially inward of the tubular body and cor-ent:ic with the tubular body, and the skirt projects downwardly from the curved buttom to a terminating plane which is spaced from the curved bottom, thereby providing for the support of the bottle in an upright position.

According to the present invention there is further provided a method of forming a blow-moulded bottle from a preform of PET material for containing a carbonated Si L 14,~ 4 beverage, comprising the steps of: forming the preform to have an open top portion, a closed bottom portion and a skirt portion depending on the closed bottom portion, inserting the preform in a bottle mould, blowing the bottle having a neck, a tubular body and a curved bottom from the preform in the bottle mould while simultaneously engaging and stretching the skirt portion on the closed bottom portion of the preform to form a bi-axially stretched single thickness annular depending skirt integral with the curved bottom, such that the skirt is positioned radially inward of the tubular body and concentric with the tubular body, and the skirt portion of the preform is stretched to form the skirt downwardly from the curved bottom to a terminating plane which is spaced from the curved bottom, thereby providing for the support of the bottle in an upright position.

According to the present invention there is further provided an apparatus for manufacturing a blow-moulded bottle formed from PET for containing a carbonated ebeverage, comprising: bottle mould capable of receiving a bottle preform having an open neck portion, a closod bottom Sportion and a skirt portion depending from the closed bottom portion, o ul stretching fingers which extend into the bottle mould through a bottom of the mould, the stretching fingers having distal ends capable of engaging with the skirt portion of the bottle preform within the mould, and a cam positioned to guide the stretching fingers dhie the bottle is blown from the bottle preform, the stretching fingers mounted for unison movement while retracting from within the mould, wherein the bottle having a neck, a tubular body and a curved bottom is capable of being blown from the bottle preform in the mould, the stretching fingers engaging the skirt portion of the bottle preform when the

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-4A bottle is being blown and the cam causing the stretching fingers to expand radially while moving axially to a longitudinal centre axis of the bottle, thus forming a bi-axially stretched single thickness annular depending skirt formed integrally with the curved bottom of the bottle, the skirt being positioned radially inward of the tubular body of the bottle and concentric with the tubular body and extending downwardly from the curved bottom to a terminating plane which is spaced from the curved bottom, thereby providing for the support of the bottle in an upright position.

Brief Description of the Drawings In order that the present invention might be more fully understood, preferred embodiments will be described hereinafter by way of example only with reference to the accompanying drawings in which: Fig. 1 is a perspective view of a bottle maide in accordance with a preferred embodiment of the invention; Fig. 2 is an enlarged fragmentary sectional view of the pressure bottom of the bottle, taken generally along the line 2-2 of Fig. 1; Fig. 3 is an enlarged sectional view through the preform of this embodiment and employed in the making of the bottle of Fig. 1; t e I i iii Li-.llip_-f i Fig. 4 is a perspective view, with parts broken away, showing the mould mechanism of this embodiment with the preform of Fig. 3 inserted within a mould cavity; Fig. 5 is a view similar to Fig. 2 showing the partially formed bottle during the blow-moulding operation; Fig. 6 is a view similar to Fig. 4 showing a further stage in the moulding operation; Fig. 7 is a view similar to Fig. 4 showing the moulding operation at its completed or final stage; Fig. 8 is a transverse section through the skirt forming mechanism of this embodiment showing the position of the parts at the entry of the fingers into the skirt portion of the preform, as illustrated in Fig. 4; Fig. 9 is a view similar to Fig. 8 showing the moved position of the fingers into gripping engagement with the depending skirt portion of the preform; a Fig. 10 is a view of the parts similar to Fig. 8 but showing the parts in a further moved position a: 0corresponding generally to the position shown in Fig. 6; Fig. 11 is a view similar to Fig. 8 and showing the S* 00 S"position of the parts generally corresponding to the view thereof in Fig. 7; and Fig. 12 is a plan view looking into the mechanism in which the fingers are in the position as illustrated in Go Fig. 9.

*00 (i Description of Preferred Embodiments A pressure bottle for carbonated beverages and the like, in accordance with a preferred embodiment of the invention, includes a pressure bottom, in which the bottom seat.

is formed with an integral single thickness annular S. depending support skirt. The bottle is blown from a go preform which is similarly formed with an annular skirt portion formed about a closed bottom. During the blowing of the preform into the shape of the bottle, in the bottle mould, an annular array of fingers with distal ends engage the skirt portion of the preform and stretch it radially of .i i 6 -6the geometric center of the preform concurrently with the preform movement, under the influence of the blowing force, into the mating bottom surface of the mould. This stretching and guiding movement as provided by the finger operated mechanism occurs concurrently with and by reason of, the blowing force exerted on the p,--form in the mould, so that an annular single thickness skirt is formed on the resulting bottle simultaneously with the blowing of the bottle.

The bottle has a pressure bottom in whtch the integrity of the bottom and the bi-axial orientation of the material are achieved without substantial disruption of the curved bottom portion of the preform into the final bottom shape, apart from the natural stretching which occurs during the blowing operation. The depending annular skirt portion of the preform, which provides the material ultimately making up the integral, single thickness support skirt for the bottle, is engaged or contacted at accurately spaced locations on an internal or inside surface by the eeoc distal ends of fingers of the guiding and stretching mechanism, and is caused to be expanded symmetrically about the center axis Df the bottle concurrently with the blowing of the container. Thereafter, the fingers are retracted from the inside surface of the completed skirt to permit ease*: the removal of the finished container.

The radial outward movement of the array of fingers is programmed by cams to coincide with the blowing and expanding of volume of the parison, such that an annular skirt of predetermined dimension is formed in the finished article. The axial length of the skirt exceeds the maximum depth of the bottom wall of the bottle within the confines of the skirt, so that the lower circular edge of the skirt terminates in a generally common support plane and provides a stable upright support for the completed bottle.

The container or bottle, as outlined above, is formed of plastic material, having a pressure bottom incorporating an annular single thickness depending skirt pLIAIVj tEj L~4 -7which is formed as an integral part of the material of the container and which has a length in an axial direction with respect to the axis of the bottle, which length exceeds the depth of the bottom within the skirt, to form a stable support platform for holding the bottle or container in an upright position.

A preform for the blow moulding of the bottle is provided having a pressure bottom in which the preform has a generally tubular or annular skirt portion surrounding a closed and generally rounded bottom portion, in which the skirt portion of the preform is adapted to form an annular support skirt or platform on the finished container for supporting the container in an upright position.

A method and apparatus for making the self-standing exemplary container, as outlined above, includes the simultaneous forming of a single thickness integral depending skirt during the blowing of the preform in a bottle mould.

An apparatus for making the exemplary container, as outlined above, includes a plurality of axially and radially movable fingers which have distal ends proportioned to engage a depending skirt portion of a preform. The fingers are programmed to stretch the skirt portion radially simultaneously with the blowing of the preform into the shape of the container within the mould.

A stretch or forming mechanism and method, is provided in which distal ends of an annular array of fingers are configured to engage an annular skirt portion of a preform, in the interior of a blow mould. The fingers are programmed, by cams, to spread radially apart from each other while engaged with the preform skirt portion, and the mechanism is operated by physical engagement of the preform with the mechanism, during the blowing of the preform in the mould, to form a self-supporting skirt in surrounding relation to the bottom of the container.

Referring to the figures of the drawings, which illustrate preferred embodiments of the invention, a blown S1A, n1 ~L\ICIr ir Il -7A plastic pressure container or bottle in accordance with this embodiment is illustrated generally at 20 in Fig. 1.

The bottle 20 may be conventionally formed of polyethylene terephthalate (PET) for containing carbonated beverages.

The bottle is formed with a generally cylindrical wall portion 22, a neck 23, and an upper threaded end 24 adapted to receive a screw cap, as conventional. The bottle 20 is also Ci *r C

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C 0 *0*0 44 i C cO L I i ;LI~,~I WO 89/07554 WO 89/054 PCT/US89/00455 -8formed with a generally semi-spherical curved pressure bottom The bottom 25 of the bottle is formed, inwardly of its outermost diameter, with a depending integral, annular, single thickness skirt 28. The skirt 28 terminates in a generally flat or planar bottom 29 and has a length, in the axial direction of the bottle, which exceeds the maximum depth of the curved bottom 25 within the annular dimensions of the skirt 28. The skirt 28 provides the means by which the bottle is supported in a free-standing upright position.

The preform 30 from which the bottle 20 is formed, is illustrated in sectional view in Fig. 3, in which like parts are marked with like reference numbers plus 10. The preform may be formed by any conventional means, such as by injection molding, and is formed with a depending skirt portion 38, which will become the skirt 28 of the bottle extending generally axially below a closed bottom portion The preform 30 is Conventional except for the integral single thickness cylindrical skirt portion 38 extending below and axially outwardly of the curved bottom 35, from which the bottle skirt 28 is formed.

The stretching or expanding mechanism employed by this r ia oto perform the method of this an and to expand the skirt 28 to the position shown in Fig. 2, from the skirt portion 38 of the preform 30, is illustrated generally at 40 in Figs. 4 through 12. For the purpose of establishing the identity of the various parts, reference may be had to the sectional view of Fig. 8 which shows the mechanism 40 in its start or initial position at the beginning of the blow molding cycle. The expanding mechanism 40 is shown as being received within the open bottom end of a mold 41, which has a mold cavity 41a (Fig. 4) therein, and the mechanism 40 in effect forms a closure to the bottom open end of the mold, 4 \i~N4 I ii i* l~.rcl-ne~~cmr~- WO 89/07554 PCT/US89/00455 -9and is provided with parts which configure and define the shape of the bottom 25 of the bottle The mechanism 40 is mounted on an air cylinder 42, which extends outwardly of the mold cavity, on a generally upwardly extending slotted mounting sleeve 44. The upper end of the sleeve 44 supports a cylindrical body 45 of aluminum material or the like. The outer cylindrical surface of the body 45 is received in the open end of the mold cavity 41a and in effect forms a closure for the mold cavity, as shown in Fig. 4.

A hollow threaded nut 46 is received in the bottom of the body 45 and *:arries a cross pin 47. The ends of the pin are engaged in suitable tapped openings formed in the upper end of the sleeve 44. By this means the body 45, tha sleeve 44, and the air cylinder 42 are assembled as a relatively rigid unit.

The means for mechanically engaging the skirt portion 38 of the preform 30 and for causing the same to assume the position of the skirt 28 of the bottle concurrently with bottle blowing, comprises a plurality of identical elongated upstanding articulated fingers 50. The fingers havv outwardly turned distal ends 52 (Fig. 8) which are proportioned to be received as an annular array within the confines of the skirt portion 38, and are programmed to 'move radially outwardly into engagement with the skirt portion, as shown in Fig. 9, during the initial stages of the blowing operation.

The fingers 52 have lower ends which are pivotally mounted on mounting pins 53 in an annular finger support plate 55. The plate 55 is received exteriorly of the mold cavity with the Zingers mounted thereon extending into the interior of the viold, through corresponding radially i WO 39/07554 PCr/US89/00455 extending slots 54 formed in the outer vertical walls of the body 45. The support plate 55, as best shown in Fig. 9, is provided with a central opening which is slidably received on the sleeve 44 for movement between an upper position, as shown in Fig. 8, in which the fingers are guided into and received within the confines of the skirt portion 38, and a 1ower position as shown in Fig. 11, in which the fingers are caused to be spread apart to carry the skirt portion to the final position concurrently with the pressure molding of the bottom An annular, flat slotted keeper plate 56 is mounted on the upper surface of the finger support plate and retains the lower ends of the fingers, and the cross pins 53, within an upwardly opening groove 51 formed in the upper surface of the fingersupport plate 55. Compression springs 58 are inserted between the bottom of the groove 57 and the bottom of the respective fingers 50, to cause the fingers to be urged or biased rotationally outwardly, about the pins 53.

The individual fingers are provided with a first generally straight section 50a through the slots 54 and a second inwardly sloping section 50b. These sections are provided with operative cam-engaging surfaces on their respective inner and outer edges so that the concurrent movement of the fingirs may be programmed to provide the desired result.

The finger support plate 55 is connected to the air cylinder 42 by means of a cross head 60. The cross head may conveniently take the form of a nut threaded on the end of the actuating rod 63 of the air cylinder 42, and tapped to receive the threaded ends of a plurality of elongated retainer bolts 65. The inner ends of the bolts 65 are tapped to enter the crosshead 60, and pass through axially elongated d I WO 89'"7554 PCTJUS89/00455 -11slots 66 formed in the side wall of the sleeve 44 and through the plate 55. The slots 66 are the same length, and define, by their length, the extent of movement of the finger support plate 55 on the sleeve 44.

The fingers 50 are programmed to provide for the controlled stretching of the skirt portion 38 concurrently with the formation of the bottom 25 of the blown bottle in the mold cavity. As shown, for example, in Fig. 5, the preform is substantially blown into the configuration of the mold walls prior to the formation of the bottom 25 of the container 20. This is accompanied by a substantial axial lengthening of the preform in the mold cavity during the initial blowing stages, as illustrated in Fig. 5. The fingers 50 are programmed, by the expanding mechanism 40, to begin the initial radial widening or spreading substantially at the po Ation of the blowing operation shown in Fig. with completion thereof concurrently with the completion of the bottom of the bottle. This movement is accomplished by cams which operate against cam surfaces formed on the inner and outer edges of the individual fingers.

First., it is desirable to retract the fingers so that the ends 52 reside about a circle which has a diameter somewhat less than the inside diameter of the skirt 38, to provide for ease of insertion of the gripping ends 52 within the skirt portion, as shown in Fig. 8. This movement inwardly of the fingers, against the compression springs 59, is accomplished by the interengagement of outside tapered cam surfaces 70 on the straight sections 50a of the arms with an encircling outside retaining ring 72. The ring 72 is mounted by spacer blocks 73 on the upper flat surface of the body and is formed with an annularly smooth inside surface. The finger retaining ring defines the extent of spreading

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W 89/07554 PCT/US89/00455 -12movement of the fingers within the slots 54 and retains the fingers within the slots in assembled relation. The relatively short sloping cam surfaces 70 are in engagement with the retaining ring 72 only in the position illustrated inl Eigs. 4 and 8, in which the gripping ends 52 are inserted into the sleeve portion 38, and the plate 55 is in abutment with the bottom of the body During the blowing, the preform, under the influence of internal air pressure applied thereto, moves downwardly or axially of the mold cavity, and this movement is translated to the expanding mechanism 40. To assist in the translation of this movement to the mechanism including the finger support plate 55, the mechanism may be provided with a center pin 80 having a broadened head 82 proportioned to engage the curved bottom portion 35 of the preform 30, at the outer surface. The lower end of the pin 80 is threaded into the crosshead 60 and accordingly moves axially concurrently with the cross head and with the finger support plate 55. The enlarged head 82 transmits the force of z2 movement of the preform, during blowing, to the plate 55 and effects the movement of this plate and the asmembled fingers in the direction indicated by the arrows 613 in Figs. 9- 11..

The initial movement of the preform causes the parts to assume the position as shown in Fig. 9 and the distal ends 52 of the fingers 50 will move outwardly into initial gripping and confined relation to the inside surface of, the skirt portion 38. This initial outer gripping movement is assured by an inside annular cam 90 on the body 45. The inside cam engages an inside sloping surface 92 of each of the fingers 50, causing the fingers to pivot about the support pins 53 within their respective individual slots WO 89/07554 PCT/US89/00455 -13- 54. The finger retaining plate 72 is provided with sufficient clearance with the finger sections 50a to assure the outward movement of the fingers as defined by the cam and the inside tapered surface 92. Thereafter, throughout the extent of the straight sections 50a, the inside cam will ride on the inside surfaces and will continue to define this position of the fingers.

In order to illustrate the operation of the expanding mechanism 40 when approaching the end of the blow, the phantom views of the finger parts are illustrated in broken line in Fig. 10 in the relative position which the same parts occupy in Fig. 9. The full line position shows the movement of the fingers 50 radially outwardly to cause a concurrent circular expansion of the skirt portion 38 when the preform has been blown to approximately the position as illustrated in FI g. 6.

The second major programmed expanding movement of the fingers 56 is caused by the engagement of the inside sloping surfaces 95 of the finger sections 50b with a slotted cam or spreader plate 96 carried on the upper surface of the body 45. The spreader plate 96 has a somewhat concave upper surface 96a against which the bottom portion 35 of the preform will be moved in the final forming of the bottom of the bottle. The plate 96 is formed with a plurality of 25 marginal slots 97, corresponding in number to the fingers and in axial alignment with the body slots 54. The plate slots terminate at inside finger engaging surfaces 98. The surfaces 98 engage the sloping surfaces 95 of the fingers as the fingers, the pin 80, and the finger support plate 55 move downwardly within the mold during the blowing operation.

This causes the fingers, and the associated skirt portion, to be expanded concurrently with the expansion of the container L 9 i i WO 89/07554 PCT/US89/00455 -14bottom between the phantom and full line positions as illustrated in Fig. 10, accompanied by the concurrent radially outward movement of the individual fingers It has been found desirable to incorporate an annular riding member, illustrated as a stabilizing ring 1100. The ring 100 is formed with an upper molding surface 102 which forms a continuation of the upper surface 96a of the plate 96, and has the same outer diameter as the body The stabilizing ring 100 has an inside diameter at 102 which permits the ring to ride on the outer sloping surfaces of the arms 50 at the tapered portions 50b thereof. As the fingers expand to their final position as shown in Fig. 10, the stabilizing ring 100 rides down in telescoping relation to the outer surface of the spreader plate 96, with the final position thereof illustrated in Fig. 11. The outer circumference of the stabilzing ring 100 is formed with a plurality of slots 106 to provide a path for the air otherwise trapped within the mold cavity, to escape past the ring during the final portion of the blowing operation when the bottom of the preform is coming into contact with the surfaces 97 and 102.

The final portion of movement, which may have an axial extent approximately equal to the corresponding axial length of the skirt 28, is preferably accomplished without further expansion, by the engagement of a straight inside section 110 of the fingers 50, at the gripping ends 52, with the cam surface 98 of the spreader plate 96. This engagement is illustrated as just beginning in Fig. 10 and as completed in Fig. 11. In this final movement, the bottom 25 is completed, with the skirt 28 nested between the cylindrical I inside surface 102 of the stabilizing ring 100 and the finger ends 52.

i i1 WO 89/07554 PCT/US89/00455 The motive force for moving the finger assembly, including the finger support plate 55 and fingers 50, axially between its first and second positions, in the direction of the arrows 83, is the force imparted thereon by the preform itself as it is blown into the interior of the mold and bears down upon the enlarged head 82 of the pin 80. This force also causes the head 82 to tuck in the nipple 111 of plastic material on the outer surface of the bottom wall portion left by the eNtrusion gate. The pin 80 and head 82 also serve the function of preventing over-bulging of the bottom during blowing.

The air cylinder 42 is double-ended and serves a primary purpose of providing an ejecting force of the bottle when the mold is opened and for returning the spreading mechanism to its first or start position as shown in Fig. 8.

Also, the cylinder may provide a controlled air cushion, through suitable valving (not shown) during the blowing operation for assisting in controlling the rate of movement of the parison within the mold cavity.

The operation of the na t \is largely self evident from the foregoing description and from the sequence of view of Figs. 4-7 and Figs. 8-11. A preform as illustrated in Fig. 3 i, molded with the annular depending skirt portion 38, and the same is conventionally inserted into the neck of a mold cavity for blowing. The expanding mechanism 40 is moved to the elevated or start position substantially as shown in Fig. 4, with the stabilizing ring 100 in place resting on the shoulder or knee portion joining the straight sections 50a with the inwardly inclined sections 50b of the fingers. This is the position as illustrated in Fig. 4. The skirt-engaging ends 52 of the arms 50 are arranged substantially in a circular array and are received 17 I .i ,1 WO 89/07554 PCT/US89/00455 -16within the confines of the skirt portion 38 of the preform as shown in Fig. 8. This position is defined by the engagement of the outside sloping surfaces 70 with the outside cam 72.

The initial blowing movement, bearing on the head 82 of the pin 80, will move the finger support plate 55 and associated cross head 60 downwardly, and in the direction of the arrow 83, releasing the engagement of the cam surfaces with the first or outside cam 72 and simultaneously bringing the second or inside cam 90 into engagement with the inside finger surfaces 92. This movement causes the gripper ends 52 to move outwardly into firm contact with the depending skirt portion 38.

Continued blowing of the preform is accompanied by continued movement, in the direction of the arrows 38, of the" finger assembly including the finger support plate 55 and the fingers 50, as shown in Fig. 10 with the engagement of the sloping inside finger surfaces 90 and the cam surfaces 98 of the spreader plate 96, while the final movement defines the final position of the pressure bottom 25, bringing the newly formed dependent skirt 28 into the annular opening formed in the stabilizing ring 100, to the position shown in Fig. 11.

In this manner, a substantially circular, continuous, integral, single thicknress supporting skirt is formed as shown in Figs. 1 and 2 which has a lower planar edge 29, which extends in the axial direction of the bottle below the lowermost portion of the pressure bottom 25. This skirt provides a stable and firm pedestal for the completed bottle While the process, products and apparatus herein described constitute preferred embodiments of this invention, it is to be understood that the invention is not limited to these precise process, products and apparatus, and that i c WO 89/07554 PCr/US89/00455 -17changes may be made therein without departing from the scope of the invention which is defined in the appended claims.

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Claims (8)

1. A blow-moulded bottle formed from a preform of PET material for containing a carbonated beverage, the blow-moulded bottle comprising: a tubular body having a longitudinal centre axis, a neck connected to a first end of the tubular body, a curved bottom connected to a second end of the tubular body, and a bi-axially stretched single thickness annular depending skirt formed integrally with the curved bottom, wherein the skirt is positioned radially inward of the tubular body and concentric with the tubular body, and the skirt projects downwardly from the curved bottom to a terminating plane which is spaced from the curved bottom, thereby providing for the support of the bottle in an upright position.

2. A method of forming a blow-moulded bottle from a preform of PET material for containing a carbonated beverage, comprising the steps of: forming the preform to have an open top portion, a closed bottom portion and a skirt portion depending on the closed bottom portion, inserting the preform in a bottle mould, blowing the bottle having a neck, a tubular body S:: and a curved bottom from the preform in the bottle mould while simultaneously engaging and stretching the skirt portion on the closed bottom portion of the preform to form a bi-axially stretched single thickness annular depending skirt integral with the curved bottom, such that the skirt is positioned radially inward of the tubular body and concentric with the tubular body, and the skirt portion of the preform is stretched to form the skirt downwardly from the curved bottom to a terminating plane which is spaced i d.A 4 from the curved bottom, thereby providing for the support Y IIL-~~_ 19 of the bottle in an upright position.

3. A method according to claim 2 wherein the skirt portion of the preform is stretched radially outward of a longitudinal centre axis of the bottle and axially of the centre axis to form the annular skirt.

4. Apparatus for manufacturing a blow-moulded bottle formed from PET for containing a carbonated beverage, comprising: a bottle mould capable of receiving a bottle preform having an open neck portion, a closed bottom portion and a skirt portion depending from the closed bottom portion, stretching fingers which extend into the bottle mould through a bottom of the mould, the stretching fingers having distal ends capable of engaging with the skirt portion of the bottle preform within the mould, and a cam positioned to guide the stretching fingers while the bottle is blown from the bottle preform, the stretching fingers mounted for unison movement while "retracting from within the mould, wherein the bottle having a neck, a tubular body and a curved bottom is capable of being blown from the bottle preform in the mould, the stretching fingers engaging the skirt portion of the bottle peform when the bottle is being blown and the cam causing the stretching fingers to expand radially while moving axially to a longitudinal centre axis of the boti thus forming a bi-axially stretched single thickness annular depending skirt formed integrally with the carved bottom of the bottle, the skirt being positioned radially inward of the tubular body of the bottle and concentric with he tubular body and extending downwardly from the curved bottom to a terminating plane which is spaced from the curved bottom, thereby providing for the support of the bottle in an A upright position. 6 i 20 Apparatus according to claim 4, further comprising a stop member associated with the stretching fingers such that the stop member is capable of engaging with the bottle preform and is responsive to movement of the preform during blowing, thereby causing the unison movement of the fingers.

6. Apparatus according to claim 5, wherein the stop member has a surface capable of defining the curved bottom of the bottle.

7. A blow-moulded bottle formed from a preform of PET material substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

8. A method of forming a blow-moulded bottle from a preform of PET material substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings. *e tQ

9. Apparatis for manufacturing a blow-moulded bottle from A preform of PET material substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings. DATED THIS 6TA DAY OF MAY, 1992. BROADWAY COMPANIES INC, By Its Patent Attorneys: GRIFFITH HACK CO. Fellows X1istitute of Patent Attorneys of Australia. 0t