CA1176014A - Delay stretch and blow machine system - Google Patents
Delay stretch and blow machine systemInfo
- Publication number
- CA1176014A CA1176014A CA000431694A CA431694A CA1176014A CA 1176014 A CA1176014 A CA 1176014A CA 000431694 A CA000431694 A CA 000431694A CA 431694 A CA431694 A CA 431694A CA 1176014 A CA1176014 A CA 1176014A
- Authority
- CA
- Canada
- Prior art keywords
- parison
- parisons
- machine system
- forming
- mold
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Landscapes
- Blow-Moulding Or Thermoforming Of Plastics Or The Like (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
In a machine system for continuous formation of molecularly oriented plastic bottles by blowing heat-conditioned parisons comprising a plurality of parison-forming stations, i.e., sixteen (16); a plurality of blow-ing stations, but fewer in number than the number of pari-son-forming stations, i.e., four (4); and a storage area between the parison-forming and parison-blowing stations, improvements are described primarily in the storage area and in the mechanisms for transferring hot parisons from the parison-forming station to the storage area and from the storage area, sequentially in multiples, to the blowing station.
In a machine system for continuous formation of molecularly oriented plastic bottles by blowing heat-conditioned parisons comprising a plurality of parison-forming stations, i.e., sixteen (16); a plurality of blow-ing stations, but fewer in number than the number of pari-son-forming stations, i.e., four (4); and a storage area between the parison-forming and parison-blowing stations, improvements are described primarily in the storage area and in the mechanisms for transferring hot parisons from the parison-forming station to the storage area and from the storage area, sequentially in multiples, to the blowing station.
Description
7&V~a~
IMPROVED DELAY STRETCH AND BLOI~I MACHI~IE SYSTEM
This application is a division of Canadian Serial 344,143, filed January 22, 1980.
This invention is directed to a m~thod ana appara-tus for molding a plastic bottle based on the hot-blow or one-step technique for manufacture of molecularly-oriented plastic bottles. More particularly, it is directed to im-provements in a hot-blow or one-step machine system for the manufacture of plastic bottles comprising a given number of parison-forming stations, i.e., sixteen (16); a given but lesser numher of blowing stations, i.e., four (4); and a storage area between the parison-forming and parison-blowing stations, permi~ting a high degree of parison mold and blow mold utillzation and overall efficiency; and to the improved method of manufacture.
In recent years substantial effort has been di-rected to the ~ormation of molecularly-oriented plastic bottles as a :replacement, or paxtial replacement, for glass bottles. According to the prior art, the manufacture of molecularly-oriented bottles ha~e utilized either a reheat, the so-called two-stage! process and system or a hot-blow, the so-called one stage, process and system. In the reheat or two-stage process, parisons are first injection molded in a parison mold, cooled to room temperature, and stored ~or subsequent blowing into the finished bottle in a blow moldt At time of blowing, the parisons are reheated to the blowing temperature of the plastic prior to blowing. In the hot-blow or one-stage process and system, the parison is injection molded in a parison mold and, substantially immediately after formation, is transferred while at the blowing temperature to a blow mold where the parison is blown into the finished bottle.
Each of the above-noted systems and processes have advantages and disadvantages. In the reheat process and system, efficient and effective use can be made of both the parison forming and the blowing stations which need not be integrated. However, substantial thermal energy is lost during the total operation in that the parison, after forma-tion, is cooled down during storage and then reheated at the time of blowing. Moreover, the parisons from storage must be fed to the blow station, duplicating handling. The hot-blow process and system eliminates heat loss and duplicate handling. However, the advantages of the hot-blow process and system are mitigated in that conventionally in order to have proper temperature conditioning of the parison at the blowing station, for each parison station there is a corres-ponding blowing station. Since the time required for pari-son formation, including temperature conditioning, is sub-stantially longer than for parison blowing, i.e., approxi-mately twenty seconds for parison formation versus five seconds for parison blowing for a polyethylene terephthalate (PET) bottle, the blowing stations are only inefficiently used.
As described in our Canadian copending application No. 303,720, filed May 19, 1978, it is ncw recognizedthat there can be a substantial delay between parison formation and the blowing of the parison without detriment to the properties of the finished bottle. For example, tests have established that there is no significant change in tensile yie~d values for delays in blowing of the parison after parison forma-tion of up to ninety seconds and longer; and, furthermore, that temperature distrihution in the walls of the parison varies only slightly over substantial periods, Based in $ ~ ~4 part on the aforesaid recognition, a process and rnachine system is described in our copending application Serial No. 303,720 whereby the number of blow molds (N/X) is an integral fraction of the larger number (N) of parison or injection molds. A parison storage area is provided between the parison forming and blowing stations. The present invention is directed to improvements in our earlier machine system and in the process of operation to provide a machine system and process which is more compact and trouble-free. The modifications which will be more fully apparent from the following drawing and detailed description of the invention are primarily in the mechanisms employed and the methods used for taking the hot parisons from the parison-forming station;
in transferring the hot parisons to the storage unit, and taking and transferring the hot parison from the storage unit to the blow stations.
The invention to which the claims in this divisional are directed pertains to a machine system for manufacturing plastic bottles comprising a plurality of parison-forming stations, a plurality of blowing stations fewer in number than the number of parison-forming stations, a storage area for holding parisons formed at the parison-forming station, and means for transferring parisons from the parison-forming station to the storage area and from the storage area to the blowing stations. The improvement relates to the storage area including a storage plate and the transfer means frorn the storage plate to the blowing stations which transfer means includes lateral transfer means for receiving the entire plurali1y of parisons from the storage plate. Shuttle means is provided for sequentially transferring a plurality of parisons but fewer than the entire plurality of parisons from the lateral transfer means to the blowing station.
The invention also comprehends the method of forming plastic bottles comprising the steps of simultaneously forming a plurality of parisons in a closed mold at a parison-forming station, the mold comprising a plurality of parison-forming cavities and each of the cavities including a neck ring assembly, opening the mold and simultaneously receiving the plurality of hot parisons with parison gripper means and separating the parisons from the neck ring assembly, positioning the parisons in a storage - 3a -area, repeatedly withdrawing a plurality of the parisons fewer in number than the entire plurality of parisons from the storage area at substantially the blowing temperature of the parisons and transferring the parisons to a blow mold for blowing, and blowing the parisons in the blow mold until the entire plurality of parisons have been blown.
The invention also pertains to a method of forming a molecularly-oriented plastic bottle comprising the steps of forming a parison in a closed parison-forming mold, the mold including a neck ring assembly, opening the mold and removing the parison from the mold including the neck ring assembly while the parison is hot, temperature-conditioning the parison while free of the neck ring assembly in at least select areas of the parison, and stretching and blowing the parison without cooling the parison substantially below the stretch and blow temperature of the parison after the parison formation.
In the drawing, which illustrates in detail a preferred embodiment and mode of operation, FIGURE 1 is a plan view of the overall machine system;
FIGURE 2 is a side elevational view of the overall machine system;
FIGURE 3 is a cross-sectional view taken along lines 3 - 3 of FIGURE 1 showing primarily the parison take-out mechanism;
FIGURE 4 is a perspective view of one parison take-out gripper and rela-ted mechanism;
FIGURE 5 is a cross-sectional view taken along lines 5 - 5 of FIGURE 4;
FIGURE 6 is a broken-away view looking in along lines 6 - 6 of FIGURE 4;
FIGURE 7 is a plan view showing primarily the horizontal movement of the transfer mechanism for transferring parisons from the parison-forming station to the parison storage area;
FIGURE 8 is a side view partly in phantom lines showing primarily the rotary movement of the transfer mechanism 6~
for transferring parisons from the parison-~orming station to the parison storage area;
FIGURE 9 is a cross-sectional view of a single collet in the non-gripping mode which forms a part of the parison transfer mechanism;
FIGURE 10 is a cross-sectional view of a single collet taken along lines 10-10 of FIGURE 7 in the gripping mode;
FIGURE 11 is an end view of a single collet;
FIGURE 12 is a plan view of the storage plate ~or re-taining parisons, not shown;
FIGURE 13 is a side view of the heatingelementwhichmay be employed to heat-condition stored parisons;
FIGURE 14 is a broken-away plan view of the heating element shown in FIGURE 13;
~ IGURE 15 is a plan view showing primarily the lateral transfer mechanism for positioning the parisons for delivery to the shuttle for final delivery to the blow station;
FIGURE 16 is a cross-s0ctional view taken along lines 16-16 of FIGURE 15 showing a section of the lateral trans-fer mechanism of FIGURE 15;
FIGURE 17 is a schematic view showing the sequence of operation of the air cylinders of the lateral transfer me-chanism;
FIGURE 18 is a side view of a blowhead assembly in the down p~sition;
FIGURE 19 is a side view of the blowhead assembly in the up position, appearing with.Figures 17 and 20;
FIGURE 20 is a sectional view showing detail of the blowhead assembly, appearing with ~igures 17 and 19;
FIGURE 21 is a view of one blowhead assembly taken along lines 21-21 of FIGURE 18 primarily illustrating the stop mechanism of the assembly when a parison is not present;
FIGURE 22 is a view of the blow mold assembly par-tially in section;
FIGURE 22a is a plan view of the blow mold assembly;
FIGURE 23 is a plan view of the shuttle mechanism for transferring the parisons from the storage area into the blow molds;
FIGURE 24 is a cross-sectional view of the shuttle mechanism ~aken along lines 24-24 of FIGURE 23;
FIGURE 2S is a schematic view of the operation of the shuttle mechanism; and FIGURE 26 is a schematic view showing the parison and bottle movement through the machine system, with Figure 22A.
Referring now primarily to FIGURES 1 and 2, the machine system of the present application in accordance with application Serial No. 303,720 comprises an injection assem-bly 10, a parison-forming section 100, a parison take-out and transfer mechanism 200, a parison storage plate 300, a parison transfer and shuttle mechanism 400, a blow section 500, and a conveyor for taking away finished bottles 600.
Injection Assembly The injection assembly 10 is of standard or con-ventional configuration and includes a feed hopper 12 con nected to a manifold 14 through barrel and screw 16. The assembly includes a shut-off valve and accumulator piston 18 for maintaining a holding pressure on the preforms com-pensating for shrinkage as the plastic temperature is rapidly lowered after injection. "Preform" and parison are used herein interchangeably. The entire assembly is mounted on a square welclment frame 20. Details of the injection as-sembly are shown in greater detail in application Serial No.
303,720 Parison-Yorming S-tation .. . . , _ Referring now primarily to FIGURES 1, 2 and 3~ the parison-forming section 100 includes a stationary mold sec-tion 102 containing sixteen mold cavities, each mold prefer-ably having a circumferential cooling passage, all being of conventional design and, accordingly, not shown in detail, The neck ring assemblies 104 are fixed to plate 10~ and support the paxison 8 when withdrawn from the moldS The neck ring assembly and its operation are more fully described in the concurrently filed Duga application entitled "Improved Neck Ring Assembly" hereinbefore noted. Sixteen neck rings, preferably liquid cooled, are attached to plate 106. The parison-forming mold also includes a core rod mold plate 140 which is on the main movable platen of the parison-forming press and applies the force to the mold com-ponents~ The core rod mold plate contains sixteen core rods 142 which are preferably individually liquid cooled. The press is actuated by toggle means, or other suitable means including hydraulic means, carried on base 144. The parison-forming press is shown in greater detail in Serial No.
303,720.
Parison St rage Se-ction The storage section 300 serves two purposes. One is to provide a holding position for the parisons prior to transferring to the blow stations; and the other is to hold the group of preformed parisons during a conditioning heat period. The storage section 300 as best shown in FIGURE 12 comprises a storage plate made up of four coupled jaw sets formed by bars 302 and 304, each forming four holding jaws 303. In addition to the four coupled jaw sets, the s~orage plate includes two pair of longitudinally extending bars 306 and 308~ Each pair of bars 306 and 308 is driven by a rack and pinion 310~ All of the moving components of the stoxage plate are moved simultaneously by a single air cylinder 314 attached to one of bars 302 at 316, Upon actuation of air cylinder 314, piston rod 318 retracts causing bars 304 to move to~ard the cylinder and at the same time rack and pin-ion 310 causes the second pair of bars 302 to move in the opposite direction, This movement opens and closes the jaw sets and forms openings 312 when closed for holding the parisons, Take-Out And Tran'sf'er' Section Referring primarily to FIGURES 1 - 11, it will be seen that the transfer mechanism includes a take-out mechan-ism 201 which picks the hot parisons 8 from the parison-~1~ 7~
forming section 100 with gripper jaw sets 208 while theparisons are extending longitudinally on neck ring plate 106 held by neck ring assembly 104. After the parisons have cleared the parison-forming station, the control of the gripper jaws is relinquished to collets 249 which carry the parisons through a ninety degree angle and positions them for acceptance by the storage plate, previously described.
Thus, referring primarily to FIGURES 3 - 6, the take-out mechanism comprises two sets of arms 202 and 204, each set mounted on a carriage 206. Each arm in turn carries eight gripper jaws 208. Each gripper jaw comprises four separate gripping fingers 210~ The gripping fingers, at-tached to U-shaped member 212 through spring 214 and guide pin 216, are padded with an insulating material 218 to minimize heat-transfer on the body surface of the parison.
The U-shaped member is integral with a scissor arm 220 pivotable on pivot member 222. Each of the scissor arms 220 is attached to a support member 223. Carriage 206 is moved transversely into andout of the parison-forming section by a single air cylinder 230 Each set of eight gripper jaws is operated individually by air cylinders 232 and 234 mov-ing ac~uator members 203 ana 205 in conjunction with rack and pinion 231. The take-out mechanism extends into the parison section, picks the hot parisons from the parison-forming stat:ion with gripper jaws 208 working in conjunc-tion with the neck ring assembly, as previously defined, and carries the preforms into the position shown in F~GURE
3~
When the prefoxms are positioned as shown in FIGURE 3, a rotary transfer mechanism 240, referring pri-marily to FIGURES 7 and 8, laterally movable on support xods 242 and 244 by air cylinder 246, transports the preforms from the take-out gripping fingers 210 to the storage plate 300, positioning the preform ir. a vertical base do~n posi-tion. The rotary transfer mechanism or unit includes a pivotally rnounted frame 247 to rotate transve~se pla~e 248 lP~ 4 through a ninety degree arc. The transverse plate contains sixteen air-operated collets 249 which are inserted into the open ends of the preforms, then expanded to hold each preform securely.
Each collet 249 comprises, as seen most clearly from FIGURES 9 ~ 11, a probe member 250 securely anchored at base members 252 by screws 254 to transverse plate 248.
The probe member includes an outer sleeve 256 and an inner sleeve 258 spaced therefrom. The outer sleeve contains slits 260 at its end~ as seen most clearly in FIGURE 11;
whereas the inner sleeve fits snugly onto a collet actuating member 262 which ends in a camming surface 264 which coacts with the outer sleeve. Additionally, there is an O-ring member 266 which circumscribes the outer sleeve 256. Ac-tuating member 262 is act~d upon by spring 268 when plate 270, actuated by air cylinder 271, simultaneously contacts each actuating member and presses inward against spring 268.
As best shown in FIGURE 9, camming surface 264 is pushed inward and sleeve member 256 is contracted by O-ring 266 so that the collet will enter a parison 8. Upon release of pressure on actuator 262 by plate 270, the end of the collets are expanded by surface 264 to grip the parison 8.
The transfer mechanism as shown most clearly in FIGURES 7 and 8 is pivotally mounted at 276 to allow trans-verse plate 248 when retracted fully in the direction of the arrows in FIGURE 7 to rotate ninety degrees carrying the colle*s and parisons into the vertical position through actuation of air cylinder 278. When plate 24a is in the vertical position as shown in ~IGURE 8, the parisons con-trolled by collets 249 are lowered vertically to be receivedby storage plate 300 with closing of jaws 303. Plate 270 actuates members 262 to release the parisons from the col-lets as plate 24~ is retracted vertically by air cylinder 246.
Temperature-Conditionlng Element The storage section includes, in addition to storage plate 300, a heat-conditioniny element 350 whi~h, as best seen in FIGURES 13 and 14, is vertically movable on guide rods 352. The heating element comprises sixteen individual pockets 351 for receiving parisons 8 while re-tained in storage plate 300. Each pocket contains heating elements 354 which will circumscribe the parison 8. As will be more ully apparent hereinafter, the heating element 350 must travel vertically a sufficient distance to free the path for the transverse movement of the lateral transfer device into position for the shuttle mechanism. FIGURE 13 shows the movement of the bottom 403 of the lateral transfer plate 402 and the bottoms of preforms 8. Additionally, the temperature-conditioning element is constructed so that its vertical movement is uninhibited by stationary rods 370 which carry the lateral transfer unit. This is accomplished b~ having the individual pocket units integral with a com-mon floor 353.
Lateral Transfer And Shuttle Mechanism The preformed parisons, after temperature-condi-tioning and the lowering of the heat-conditioning element 20 350, are received from the storage plate 300 by a lateral transfer unit 402, which moves in transversely between the rows of preforms in the storage plate 300~ The lateral trans-~er unit as best shown in FIGU~ES 15 and 16 comprises four ~arrier bar sets 404, 406, 408 and 410, each with indepen-dently actuating air cylinders 412 and mounted on a slidable l~teral transfer carriage 414. Each of the four carrier bar sets include encompassing gripper bars 420 and 422 which are moved about centers 424 and 426 by air cylinder 412 to for,m four sets of jaws 413, When the piStO}I rods 430 of 30 the air cylinder 412 are re.tracted, the jaws 413 are closed forming openings 432, see set 404, which hold the preform.
When the piston is extended as in 406, 4Q8 and 410, the jaws 413 are open. This permits, as will be more fully de-veloped hereinafter, the parisons of the respective rows to be individually and sequentially received by the shuttle mechanism. The transfer carriage is moved transversely .~7~;0~ge into and out from under the storage plate by a single ~ir cylinder 416.
After the transfer unit has been moved in, and transversely out from under the storage plate after collect-ing the preforms, individual actuating cylinders then ad-vance or index the carriage so that each carriage bar set is posiiioned with respect t~ the shuttle to transfer a row of four preforms to the blow mold as schematically shown in FIG~RE 17. The indexing carriage dispenses all four rows and then returns to the storage plate for a new set of pre-forms.
The individual rows of preforms in the lateral transfer unit are positioned for receipt by the shuttle me-chanism by three individual actuating cylinders, i.e., cylinder 416 and cylinders 440 and 442 shown in phantom Iines in FIGURE 15. As shown schematically in FIGURE 17, the first cylinder, 416, and the second cylinder are fully extended and the third cylinder is retracted when under the storage plate. When the first cylinder is retracted, the second c~linder is extended and the third cylinder is re-tracted, the first row of parisons is positioned for receipt by the shuttle. Once the ~ixst row of paris~ns is received, the latexal transfer mechanism is indexed by the second cy-linder remaining extended, with the third cylinder being extended, to position the second row of parisons for receipt by the shuttle mechanism~ The third row of parisons or pre~orms is positioned by the second cylinder being retracted and the third cylinder retracted. The fourth and last row is positioned again by the third cylinder being extended.
As will be apparent, the lateral transfer jaws must provide a free path for the preforms in two directio~s to permit the shuttle mechanism to come in and select and remove the preforms and to permit the lateral transfer jaws to pass between the downward extended pre~orms in the storage plate.
The preforms are received from the lateral trans-fer jaws by shuttle mechanism 45Q. The shuttle mechanism as best shown in FIGU~ES 23 and 24 includes eight spaced apart jaw sets 454 arranged side by side on shuttle frame 451 a-t fixed pivots 455 and 4S7. The jaws of the shuttle are opened and closed by the co-action of air cylinders 462 and 464. The shuttle mechanism is traversed between two positions as shown diagrammatically in FIGURE 25 by a single air cylinder 460.
Referring to FIGURE 25, in a first and start-up position A, the shuttle mechanism receives a first set of four preforms from the first row of the lateral transfer unit and in a second position B deposits the preforms in the blow mold 502 of the blow mold section. Thereafter, the shuttle mechanism moves forward during the blowing of the ¦ first set of parisons to a third position C to receive a second set of four preforms from row two of the lateral trans-fer unit~ Thereafter, the shuttle mechanism in a fourth position D deposits four blown bottles 608 taken from the blow molds, i.e., the bottles formed from the preforms of row one; onto a conveyor assembly 600 and deposits four fresh parisons into the blow mold. The cycle is continuous-ly repeated.
Blow Mold Section The blow mold section 500 comprises four liquid-- cooled molds 502 which split simultaneously for opening and closing o~ the molds to allow for insertion of the parisons and for finished bottle removal. As best shown in FIGURE 22, the blow mold comprises side sections 504 and 506, and bot-tom section 508. The side sections 504 and 506 move away from each other simultaneously as frame member 510 moves in-ward through actuation of to~gle linkage 512 about fixed center 514. As mold halves 504 and 506 commence opening, the bottom section of the mold 508 moVes downward in slideway 521 as frame member 510 moves inward and linka~e 520 is ac-tuated pivoting about points 519, 522, 523 and 524.
Once the molds are closed, the blo~heads 528, as best shown in FIGURES 18 - 21~ are brouqht into the down V~4 position actuating stretch rod 530. The positioning and actuation of the blowheads is controlled by toygle arrange-ment 540 movin~ carriage 542 through camming groove 544 with air cylinder 546. The toggle and cam arrangement lock the blowhead into the down position.
As seen in FIGURE 20, when the blowhead is in the down position, the flange 9 on the neck ring of the parison rests on top part 548 of the blow mold. In this position the jaws 454 of the shuttle mechanism because of their con-struction are free to move in under the blowhead and aroundlegs 550 and engage the parison above the top of the parison flange. The shuttle jaw construction, permitting the jaws to come into position and to be removed while the blow mold is in the operating or down position, permits greater speed in the operation of the unit.
As is also apparent ~rom FIGURE 20, the blowhead is actuated by delivering air under high pressure through passage 525 to the top of the blowhe~d 528 positioned in sleeve 529 by spring 526. The air pressure on the top of the blowhead causes the blowhead to slide in sleeve 529, and effectively functions as a piston forcing the blowhead into sealing engagement with elastomeric seal 527. The downward thrust of the blowhead is opposed by the toggle and cam lock arrangement. As is apparent, legs 550 do not contact the mold if a preform is present; but in the eVent a preform is not present, the legs will rest on the top of the blow mold. This prevents downward movement of the blow-head in theevent a parison is inadvertently not present.
Conveyor Section The conveyox section 600 comprises a suitable endless belt 602 on rollers 604 constructed and arranged in ~elation to the blow mold section to receive and convey away finished bottles 608 dropped thereon by shuttle 450.
Mode Of Operation Of Machine System The machine system is designed to operate on a 20-second cycle, suitable for PET However, the cycle can 1.~ 4 be varied to suit processing requirements for any particular plastic material.
As described in Serial No 303,720, at the parison-forming station the parison or preform press, at the com-mencement of theoperation, is closed with the neck ring car-rier plate 106 and core rod plate 140 in the mold position and with the injection nozzles forward for injection. Gran-ular plastic from feed hopper 12 which has been properly plasticized in the reciprocating screw 16 is injected under high ram pressure through the manifold into the pre~orm mold cavities, not shown. The nozzle valve c~oses permitting the injector screw to plasticize the next charge for the next set of parisons. The accumulator piston 18 maintains the holding pressure on the preforms, compensating for shrinkage as the plastic temperature is rapidly lowered~ After the injection of the parison is complete and the parison tem-perature-conditioned, the core rod platen 140 is retra~ted as neck ring carrier plate 106 is also being retracted car-rying the finished parisons 8 from within the parison mold plate 102 as best shown in FIGURE 1. The preforms are then ready to be transferred to the storage area.
As best shown in FIGURES 1 and 2, the take-out mechanism 201 thrusts into the opened parison mold and the gripper jaws 208 grasp each preform at ~hich time the neck ring assemblles 104 open as previously described The take-out mechanisrn riding on carriage 206 withdraws the parisons allowing the injection mold to close to begin the cycle for forming the next group of preforms.
Simultaneous with the closing of the mold and the 3Q commencement of formation o~ a new set of parisons, the ro-tar~ transfer mechanism 240 as best shown in FIGURE 7 is moved inward transversely by air cylinder 246 on rods 242 and 244. Upon moving forward, the gripper jaws 208 Qn the take-out mechanism holding the parisons permits the parisons to be centered against the stop bar 238 as a result of the neck flange 9 o~ parison 8 being brought into contact with .4 the s~op bar 238 by colle~s 249. This is desirable in order that all of the parisons are exactly even for subsequent gripping by the collets and jaws of the storage plate, la-teral transfer unit and the shuttle jaws as shown in FIGURE
26 where SR-l is the first position of stop rail 238; SR-2 is the second position of the stop rail, i.e., butted against parison flange 9; SPJ is the storage plate jaws; LTJ is the lateral transfer jaw; SMJ is the shuttle mechanism jaw, and BM is the top part of the blow mold. With the parison but-ting up against the stop bar 238, actuator plate 270 simul-taneously contacts all sixteen collet actuators 262 and the collet probe 250 enters the necks of the parisons. Substan-tially simultaneously, the take-out gripper jaws 208 are released as shown in ~IGURE 7 and the collets grip the pre-forms, permitting the preform to be withdrawn by the trans-verse movement of the collets when piston rod 245 of air cylinder 246 is retracted. T~e transverse pla~e 248 is then xotated downward ninety degrees as best shown in FIGURE 8, to place the preforms in position in the storage plate 300 At the time the transverse plate 248 carrying the collets 249 is rotated downward, the jaws 303 of the storage plate are open After the parisons are rotated into the vertical position, the jaws of the storage plate close securing the preforms while the collets are released and retracted, The transverse p:Late is rotated ninety degrees upward into a position for receiving the next group of parisons~
The storage plate 300 after receiving the parisons permits temperature-conditioning of the parisons with heat-conditioning element 350, As shown in ~IGURES 13 and 14 the storage element riding on ~ertical rods 352 can rise upward clearing the bottom 403 of the lateral transfer unit 402 and encompassing the preforms 8 while in the storage plate. As is apparent from the broken-away view in FIGURE
14, the heat-conditionin~ unit is constructed in order that the pockets 351 avoid carrier rod 370.
~ hen the prefo~ms are properly heat~conditioned P~ 4 within the heating pockets, the heating element is lowered clearing the way for the transverse movement of the lateral transfer unit 402. The lateral transfer mechanism as best shown in FIGURES 15 and 16 enters under the storage plate being guided between the rows of parisons with the lateral transfer jaws being open. After the lateral transfer unit is properly positioned, the jaws of the lateral transfer unit are closed and the jaws of the storage plate are opened.
The parisons are withdrawn transversely from under the stor-age plate by large air cylinder 416. The first row of pari-sons are then positioned for acceptance by the shuttle me-chanism 450. The shuttle jaws 454 come in, grasp the first row of preforms, position A of FIGURE 25; and thereafter retract to posi~ion B, depositing the first row of preforms into the open blow molds 502~ Simultaneously, the blow molds close about the preforms while the shuttle jaws are still in place and the lateral transfer unit indexes the second row of parisons into the shuttle position as shown in FIGURE 17~ The shuttle jaws open and extend to the posi-tion C in FIGURE 25 to secure a second set of parisons.Simultaneous with this movement, the blowhead of the blcw mold assembly comes down and the first set of parisons are blown to the finished bottles, The jaws of the shuttle close arQund the second row of preforms and around the fin-ished bottles 608 in the blo~ molds. The blowhead rises, the blow mold opens, and the shuttle mechanism retracts into position D of FIGURE 25 carrying the finished bottles to conVeyor mechanism 600 while positioning the second row of preforms in the blow molds~ Simultaneously the blow mold 30 closes, the third row of parisons are indexed into the shut-tle position as shown in FIGURE 17, and the shuttle returns to position A for the third row of preforms. The cycle is continuously repeated.
Although the improved machine system has been de-scribed usiny a 20~-second cycle designed for the use of PET, the machine system can be modified to accommodate the curing characterlstics of any plastic material. Moreover, although the improved machine system has been described using sixteen preform molds and four blow molds, the ratio can be modified to best suit a given temperature cycle. The ratios can be-any whole number such as 8 to 2; 4 to 1; 9 to 3; 3 to 1, or the like.
Additionally, the machine system and process, since the neck ring is removed from the parison after formation at the parison-forming station of the neck ring finish, permits the complete temperature-conditioning of the neck and shoul-der areas of the parison. Thus, in a system in which the neck ring mechanism is used as a-means of transferring the parison from the parison-forming station to the blow station, it is not possible in view of the heat-transfer characteris-tics of the neck ring to effectively temperature-condition the neck and shoulder areas of the parison. This can lead to defects in the neck and shoulder areas of the final bot-tles. According to the present machine system and prGcess, it is possible to apply heat or remove heat during the pari-son transfer or storage period to and from those and onlythose areas o~ the parison requiring temperature-condition-ing. This temperature-conditioning permits a better transi-tion from the neck finish to the body of the final bottles providing, inter_alia, a better appearance.
~ hough the abilit~ to heat-condition the parison including in select areas is a unique advantage o~ the pre-sently described machine s~stem and process, it is to be understood that it may not be essential, depending upon the total operating conditions, to use a heat conditioning element, If the heat-conditioning element is not emplo~ed, various modifications can be made in both the rotary trans-fer mechanism and in the lateral transfer mechanism, As will be apparent to one skilled in the art) various modifications can be made in the hereinbefore de-scribed m~chine system and process with respect to making improved bottles. The pre~erred embodiments described are not to be construed as a limitation o~ the invention.
IMPROVED DELAY STRETCH AND BLOI~I MACHI~IE SYSTEM
This application is a division of Canadian Serial 344,143, filed January 22, 1980.
This invention is directed to a m~thod ana appara-tus for molding a plastic bottle based on the hot-blow or one-step technique for manufacture of molecularly-oriented plastic bottles. More particularly, it is directed to im-provements in a hot-blow or one-step machine system for the manufacture of plastic bottles comprising a given number of parison-forming stations, i.e., sixteen (16); a given but lesser numher of blowing stations, i.e., four (4); and a storage area between the parison-forming and parison-blowing stations, permi~ting a high degree of parison mold and blow mold utillzation and overall efficiency; and to the improved method of manufacture.
In recent years substantial effort has been di-rected to the ~ormation of molecularly-oriented plastic bottles as a :replacement, or paxtial replacement, for glass bottles. According to the prior art, the manufacture of molecularly-oriented bottles ha~e utilized either a reheat, the so-called two-stage! process and system or a hot-blow, the so-called one stage, process and system. In the reheat or two-stage process, parisons are first injection molded in a parison mold, cooled to room temperature, and stored ~or subsequent blowing into the finished bottle in a blow moldt At time of blowing, the parisons are reheated to the blowing temperature of the plastic prior to blowing. In the hot-blow or one-stage process and system, the parison is injection molded in a parison mold and, substantially immediately after formation, is transferred while at the blowing temperature to a blow mold where the parison is blown into the finished bottle.
Each of the above-noted systems and processes have advantages and disadvantages. In the reheat process and system, efficient and effective use can be made of both the parison forming and the blowing stations which need not be integrated. However, substantial thermal energy is lost during the total operation in that the parison, after forma-tion, is cooled down during storage and then reheated at the time of blowing. Moreover, the parisons from storage must be fed to the blow station, duplicating handling. The hot-blow process and system eliminates heat loss and duplicate handling. However, the advantages of the hot-blow process and system are mitigated in that conventionally in order to have proper temperature conditioning of the parison at the blowing station, for each parison station there is a corres-ponding blowing station. Since the time required for pari-son formation, including temperature conditioning, is sub-stantially longer than for parison blowing, i.e., approxi-mately twenty seconds for parison formation versus five seconds for parison blowing for a polyethylene terephthalate (PET) bottle, the blowing stations are only inefficiently used.
As described in our Canadian copending application No. 303,720, filed May 19, 1978, it is ncw recognizedthat there can be a substantial delay between parison formation and the blowing of the parison without detriment to the properties of the finished bottle. For example, tests have established that there is no significant change in tensile yie~d values for delays in blowing of the parison after parison forma-tion of up to ninety seconds and longer; and, furthermore, that temperature distrihution in the walls of the parison varies only slightly over substantial periods, Based in $ ~ ~4 part on the aforesaid recognition, a process and rnachine system is described in our copending application Serial No. 303,720 whereby the number of blow molds (N/X) is an integral fraction of the larger number (N) of parison or injection molds. A parison storage area is provided between the parison forming and blowing stations. The present invention is directed to improvements in our earlier machine system and in the process of operation to provide a machine system and process which is more compact and trouble-free. The modifications which will be more fully apparent from the following drawing and detailed description of the invention are primarily in the mechanisms employed and the methods used for taking the hot parisons from the parison-forming station;
in transferring the hot parisons to the storage unit, and taking and transferring the hot parison from the storage unit to the blow stations.
The invention to which the claims in this divisional are directed pertains to a machine system for manufacturing plastic bottles comprising a plurality of parison-forming stations, a plurality of blowing stations fewer in number than the number of parison-forming stations, a storage area for holding parisons formed at the parison-forming station, and means for transferring parisons from the parison-forming station to the storage area and from the storage area to the blowing stations. The improvement relates to the storage area including a storage plate and the transfer means frorn the storage plate to the blowing stations which transfer means includes lateral transfer means for receiving the entire plurali1y of parisons from the storage plate. Shuttle means is provided for sequentially transferring a plurality of parisons but fewer than the entire plurality of parisons from the lateral transfer means to the blowing station.
The invention also comprehends the method of forming plastic bottles comprising the steps of simultaneously forming a plurality of parisons in a closed mold at a parison-forming station, the mold comprising a plurality of parison-forming cavities and each of the cavities including a neck ring assembly, opening the mold and simultaneously receiving the plurality of hot parisons with parison gripper means and separating the parisons from the neck ring assembly, positioning the parisons in a storage - 3a -area, repeatedly withdrawing a plurality of the parisons fewer in number than the entire plurality of parisons from the storage area at substantially the blowing temperature of the parisons and transferring the parisons to a blow mold for blowing, and blowing the parisons in the blow mold until the entire plurality of parisons have been blown.
The invention also pertains to a method of forming a molecularly-oriented plastic bottle comprising the steps of forming a parison in a closed parison-forming mold, the mold including a neck ring assembly, opening the mold and removing the parison from the mold including the neck ring assembly while the parison is hot, temperature-conditioning the parison while free of the neck ring assembly in at least select areas of the parison, and stretching and blowing the parison without cooling the parison substantially below the stretch and blow temperature of the parison after the parison formation.
In the drawing, which illustrates in detail a preferred embodiment and mode of operation, FIGURE 1 is a plan view of the overall machine system;
FIGURE 2 is a side elevational view of the overall machine system;
FIGURE 3 is a cross-sectional view taken along lines 3 - 3 of FIGURE 1 showing primarily the parison take-out mechanism;
FIGURE 4 is a perspective view of one parison take-out gripper and rela-ted mechanism;
FIGURE 5 is a cross-sectional view taken along lines 5 - 5 of FIGURE 4;
FIGURE 6 is a broken-away view looking in along lines 6 - 6 of FIGURE 4;
FIGURE 7 is a plan view showing primarily the horizontal movement of the transfer mechanism for transferring parisons from the parison-forming station to the parison storage area;
FIGURE 8 is a side view partly in phantom lines showing primarily the rotary movement of the transfer mechanism 6~
for transferring parisons from the parison-~orming station to the parison storage area;
FIGURE 9 is a cross-sectional view of a single collet in the non-gripping mode which forms a part of the parison transfer mechanism;
FIGURE 10 is a cross-sectional view of a single collet taken along lines 10-10 of FIGURE 7 in the gripping mode;
FIGURE 11 is an end view of a single collet;
FIGURE 12 is a plan view of the storage plate ~or re-taining parisons, not shown;
FIGURE 13 is a side view of the heatingelementwhichmay be employed to heat-condition stored parisons;
FIGURE 14 is a broken-away plan view of the heating element shown in FIGURE 13;
~ IGURE 15 is a plan view showing primarily the lateral transfer mechanism for positioning the parisons for delivery to the shuttle for final delivery to the blow station;
FIGURE 16 is a cross-s0ctional view taken along lines 16-16 of FIGURE 15 showing a section of the lateral trans-fer mechanism of FIGURE 15;
FIGURE 17 is a schematic view showing the sequence of operation of the air cylinders of the lateral transfer me-chanism;
FIGURE 18 is a side view of a blowhead assembly in the down p~sition;
FIGURE 19 is a side view of the blowhead assembly in the up position, appearing with.Figures 17 and 20;
FIGURE 20 is a sectional view showing detail of the blowhead assembly, appearing with ~igures 17 and 19;
FIGURE 21 is a view of one blowhead assembly taken along lines 21-21 of FIGURE 18 primarily illustrating the stop mechanism of the assembly when a parison is not present;
FIGURE 22 is a view of the blow mold assembly par-tially in section;
FIGURE 22a is a plan view of the blow mold assembly;
FIGURE 23 is a plan view of the shuttle mechanism for transferring the parisons from the storage area into the blow molds;
FIGURE 24 is a cross-sectional view of the shuttle mechanism ~aken along lines 24-24 of FIGURE 23;
FIGURE 2S is a schematic view of the operation of the shuttle mechanism; and FIGURE 26 is a schematic view showing the parison and bottle movement through the machine system, with Figure 22A.
Referring now primarily to FIGURES 1 and 2, the machine system of the present application in accordance with application Serial No. 303,720 comprises an injection assem-bly 10, a parison-forming section 100, a parison take-out and transfer mechanism 200, a parison storage plate 300, a parison transfer and shuttle mechanism 400, a blow section 500, and a conveyor for taking away finished bottles 600.
Injection Assembly The injection assembly 10 is of standard or con-ventional configuration and includes a feed hopper 12 con nected to a manifold 14 through barrel and screw 16. The assembly includes a shut-off valve and accumulator piston 18 for maintaining a holding pressure on the preforms com-pensating for shrinkage as the plastic temperature is rapidly lowered after injection. "Preform" and parison are used herein interchangeably. The entire assembly is mounted on a square welclment frame 20. Details of the injection as-sembly are shown in greater detail in application Serial No.
303,720 Parison-Yorming S-tation .. . . , _ Referring now primarily to FIGURES 1, 2 and 3~ the parison-forming section 100 includes a stationary mold sec-tion 102 containing sixteen mold cavities, each mold prefer-ably having a circumferential cooling passage, all being of conventional design and, accordingly, not shown in detail, The neck ring assemblies 104 are fixed to plate 10~ and support the paxison 8 when withdrawn from the moldS The neck ring assembly and its operation are more fully described in the concurrently filed Duga application entitled "Improved Neck Ring Assembly" hereinbefore noted. Sixteen neck rings, preferably liquid cooled, are attached to plate 106. The parison-forming mold also includes a core rod mold plate 140 which is on the main movable platen of the parison-forming press and applies the force to the mold com-ponents~ The core rod mold plate contains sixteen core rods 142 which are preferably individually liquid cooled. The press is actuated by toggle means, or other suitable means including hydraulic means, carried on base 144. The parison-forming press is shown in greater detail in Serial No.
303,720.
Parison St rage Se-ction The storage section 300 serves two purposes. One is to provide a holding position for the parisons prior to transferring to the blow stations; and the other is to hold the group of preformed parisons during a conditioning heat period. The storage section 300 as best shown in FIGURE 12 comprises a storage plate made up of four coupled jaw sets formed by bars 302 and 304, each forming four holding jaws 303. In addition to the four coupled jaw sets, the s~orage plate includes two pair of longitudinally extending bars 306 and 308~ Each pair of bars 306 and 308 is driven by a rack and pinion 310~ All of the moving components of the stoxage plate are moved simultaneously by a single air cylinder 314 attached to one of bars 302 at 316, Upon actuation of air cylinder 314, piston rod 318 retracts causing bars 304 to move to~ard the cylinder and at the same time rack and pin-ion 310 causes the second pair of bars 302 to move in the opposite direction, This movement opens and closes the jaw sets and forms openings 312 when closed for holding the parisons, Take-Out And Tran'sf'er' Section Referring primarily to FIGURES 1 - 11, it will be seen that the transfer mechanism includes a take-out mechan-ism 201 which picks the hot parisons 8 from the parison-~1~ 7~
forming section 100 with gripper jaw sets 208 while theparisons are extending longitudinally on neck ring plate 106 held by neck ring assembly 104. After the parisons have cleared the parison-forming station, the control of the gripper jaws is relinquished to collets 249 which carry the parisons through a ninety degree angle and positions them for acceptance by the storage plate, previously described.
Thus, referring primarily to FIGURES 3 - 6, the take-out mechanism comprises two sets of arms 202 and 204, each set mounted on a carriage 206. Each arm in turn carries eight gripper jaws 208. Each gripper jaw comprises four separate gripping fingers 210~ The gripping fingers, at-tached to U-shaped member 212 through spring 214 and guide pin 216, are padded with an insulating material 218 to minimize heat-transfer on the body surface of the parison.
The U-shaped member is integral with a scissor arm 220 pivotable on pivot member 222. Each of the scissor arms 220 is attached to a support member 223. Carriage 206 is moved transversely into andout of the parison-forming section by a single air cylinder 230 Each set of eight gripper jaws is operated individually by air cylinders 232 and 234 mov-ing ac~uator members 203 ana 205 in conjunction with rack and pinion 231. The take-out mechanism extends into the parison section, picks the hot parisons from the parison-forming stat:ion with gripper jaws 208 working in conjunc-tion with the neck ring assembly, as previously defined, and carries the preforms into the position shown in F~GURE
3~
When the prefoxms are positioned as shown in FIGURE 3, a rotary transfer mechanism 240, referring pri-marily to FIGURES 7 and 8, laterally movable on support xods 242 and 244 by air cylinder 246, transports the preforms from the take-out gripping fingers 210 to the storage plate 300, positioning the preform ir. a vertical base do~n posi-tion. The rotary transfer mechanism or unit includes a pivotally rnounted frame 247 to rotate transve~se pla~e 248 lP~ 4 through a ninety degree arc. The transverse plate contains sixteen air-operated collets 249 which are inserted into the open ends of the preforms, then expanded to hold each preform securely.
Each collet 249 comprises, as seen most clearly from FIGURES 9 ~ 11, a probe member 250 securely anchored at base members 252 by screws 254 to transverse plate 248.
The probe member includes an outer sleeve 256 and an inner sleeve 258 spaced therefrom. The outer sleeve contains slits 260 at its end~ as seen most clearly in FIGURE 11;
whereas the inner sleeve fits snugly onto a collet actuating member 262 which ends in a camming surface 264 which coacts with the outer sleeve. Additionally, there is an O-ring member 266 which circumscribes the outer sleeve 256. Ac-tuating member 262 is act~d upon by spring 268 when plate 270, actuated by air cylinder 271, simultaneously contacts each actuating member and presses inward against spring 268.
As best shown in FIGURE 9, camming surface 264 is pushed inward and sleeve member 256 is contracted by O-ring 266 so that the collet will enter a parison 8. Upon release of pressure on actuator 262 by plate 270, the end of the collets are expanded by surface 264 to grip the parison 8.
The transfer mechanism as shown most clearly in FIGURES 7 and 8 is pivotally mounted at 276 to allow trans-verse plate 248 when retracted fully in the direction of the arrows in FIGURE 7 to rotate ninety degrees carrying the colle*s and parisons into the vertical position through actuation of air cylinder 278. When plate 24a is in the vertical position as shown in ~IGURE 8, the parisons con-trolled by collets 249 are lowered vertically to be receivedby storage plate 300 with closing of jaws 303. Plate 270 actuates members 262 to release the parisons from the col-lets as plate 24~ is retracted vertically by air cylinder 246.
Temperature-Conditionlng Element The storage section includes, in addition to storage plate 300, a heat-conditioniny element 350 whi~h, as best seen in FIGURES 13 and 14, is vertically movable on guide rods 352. The heating element comprises sixteen individual pockets 351 for receiving parisons 8 while re-tained in storage plate 300. Each pocket contains heating elements 354 which will circumscribe the parison 8. As will be more ully apparent hereinafter, the heating element 350 must travel vertically a sufficient distance to free the path for the transverse movement of the lateral transfer device into position for the shuttle mechanism. FIGURE 13 shows the movement of the bottom 403 of the lateral transfer plate 402 and the bottoms of preforms 8. Additionally, the temperature-conditioning element is constructed so that its vertical movement is uninhibited by stationary rods 370 which carry the lateral transfer unit. This is accomplished b~ having the individual pocket units integral with a com-mon floor 353.
Lateral Transfer And Shuttle Mechanism The preformed parisons, after temperature-condi-tioning and the lowering of the heat-conditioning element 20 350, are received from the storage plate 300 by a lateral transfer unit 402, which moves in transversely between the rows of preforms in the storage plate 300~ The lateral trans-~er unit as best shown in FIGU~ES 15 and 16 comprises four ~arrier bar sets 404, 406, 408 and 410, each with indepen-dently actuating air cylinders 412 and mounted on a slidable l~teral transfer carriage 414. Each of the four carrier bar sets include encompassing gripper bars 420 and 422 which are moved about centers 424 and 426 by air cylinder 412 to for,m four sets of jaws 413, When the piStO}I rods 430 of 30 the air cylinder 412 are re.tracted, the jaws 413 are closed forming openings 432, see set 404, which hold the preform.
When the piston is extended as in 406, 4Q8 and 410, the jaws 413 are open. This permits, as will be more fully de-veloped hereinafter, the parisons of the respective rows to be individually and sequentially received by the shuttle mechanism. The transfer carriage is moved transversely .~7~;0~ge into and out from under the storage plate by a single ~ir cylinder 416.
After the transfer unit has been moved in, and transversely out from under the storage plate after collect-ing the preforms, individual actuating cylinders then ad-vance or index the carriage so that each carriage bar set is posiiioned with respect t~ the shuttle to transfer a row of four preforms to the blow mold as schematically shown in FIG~RE 17. The indexing carriage dispenses all four rows and then returns to the storage plate for a new set of pre-forms.
The individual rows of preforms in the lateral transfer unit are positioned for receipt by the shuttle me-chanism by three individual actuating cylinders, i.e., cylinder 416 and cylinders 440 and 442 shown in phantom Iines in FIGURE 15. As shown schematically in FIGURE 17, the first cylinder, 416, and the second cylinder are fully extended and the third cylinder is retracted when under the storage plate. When the first cylinder is retracted, the second c~linder is extended and the third cylinder is re-tracted, the first row of parisons is positioned for receipt by the shuttle. Once the ~ixst row of paris~ns is received, the latexal transfer mechanism is indexed by the second cy-linder remaining extended, with the third cylinder being extended, to position the second row of parisons for receipt by the shuttle mechanism~ The third row of parisons or pre~orms is positioned by the second cylinder being retracted and the third cylinder retracted. The fourth and last row is positioned again by the third cylinder being extended.
As will be apparent, the lateral transfer jaws must provide a free path for the preforms in two directio~s to permit the shuttle mechanism to come in and select and remove the preforms and to permit the lateral transfer jaws to pass between the downward extended pre~orms in the storage plate.
The preforms are received from the lateral trans-fer jaws by shuttle mechanism 45Q. The shuttle mechanism as best shown in FIGU~ES 23 and 24 includes eight spaced apart jaw sets 454 arranged side by side on shuttle frame 451 a-t fixed pivots 455 and 4S7. The jaws of the shuttle are opened and closed by the co-action of air cylinders 462 and 464. The shuttle mechanism is traversed between two positions as shown diagrammatically in FIGURE 25 by a single air cylinder 460.
Referring to FIGURE 25, in a first and start-up position A, the shuttle mechanism receives a first set of four preforms from the first row of the lateral transfer unit and in a second position B deposits the preforms in the blow mold 502 of the blow mold section. Thereafter, the shuttle mechanism moves forward during the blowing of the ¦ first set of parisons to a third position C to receive a second set of four preforms from row two of the lateral trans-fer unit~ Thereafter, the shuttle mechanism in a fourth position D deposits four blown bottles 608 taken from the blow molds, i.e., the bottles formed from the preforms of row one; onto a conveyor assembly 600 and deposits four fresh parisons into the blow mold. The cycle is continuous-ly repeated.
Blow Mold Section The blow mold section 500 comprises four liquid-- cooled molds 502 which split simultaneously for opening and closing o~ the molds to allow for insertion of the parisons and for finished bottle removal. As best shown in FIGURE 22, the blow mold comprises side sections 504 and 506, and bot-tom section 508. The side sections 504 and 506 move away from each other simultaneously as frame member 510 moves in-ward through actuation of to~gle linkage 512 about fixed center 514. As mold halves 504 and 506 commence opening, the bottom section of the mold 508 moVes downward in slideway 521 as frame member 510 moves inward and linka~e 520 is ac-tuated pivoting about points 519, 522, 523 and 524.
Once the molds are closed, the blo~heads 528, as best shown in FIGURES 18 - 21~ are brouqht into the down V~4 position actuating stretch rod 530. The positioning and actuation of the blowheads is controlled by toygle arrange-ment 540 movin~ carriage 542 through camming groove 544 with air cylinder 546. The toggle and cam arrangement lock the blowhead into the down position.
As seen in FIGURE 20, when the blowhead is in the down position, the flange 9 on the neck ring of the parison rests on top part 548 of the blow mold. In this position the jaws 454 of the shuttle mechanism because of their con-struction are free to move in under the blowhead and aroundlegs 550 and engage the parison above the top of the parison flange. The shuttle jaw construction, permitting the jaws to come into position and to be removed while the blow mold is in the operating or down position, permits greater speed in the operation of the unit.
As is also apparent ~rom FIGURE 20, the blowhead is actuated by delivering air under high pressure through passage 525 to the top of the blowhe~d 528 positioned in sleeve 529 by spring 526. The air pressure on the top of the blowhead causes the blowhead to slide in sleeve 529, and effectively functions as a piston forcing the blowhead into sealing engagement with elastomeric seal 527. The downward thrust of the blowhead is opposed by the toggle and cam lock arrangement. As is apparent, legs 550 do not contact the mold if a preform is present; but in the eVent a preform is not present, the legs will rest on the top of the blow mold. This prevents downward movement of the blow-head in theevent a parison is inadvertently not present.
Conveyor Section The conveyox section 600 comprises a suitable endless belt 602 on rollers 604 constructed and arranged in ~elation to the blow mold section to receive and convey away finished bottles 608 dropped thereon by shuttle 450.
Mode Of Operation Of Machine System The machine system is designed to operate on a 20-second cycle, suitable for PET However, the cycle can 1.~ 4 be varied to suit processing requirements for any particular plastic material.
As described in Serial No 303,720, at the parison-forming station the parison or preform press, at the com-mencement of theoperation, is closed with the neck ring car-rier plate 106 and core rod plate 140 in the mold position and with the injection nozzles forward for injection. Gran-ular plastic from feed hopper 12 which has been properly plasticized in the reciprocating screw 16 is injected under high ram pressure through the manifold into the pre~orm mold cavities, not shown. The nozzle valve c~oses permitting the injector screw to plasticize the next charge for the next set of parisons. The accumulator piston 18 maintains the holding pressure on the preforms, compensating for shrinkage as the plastic temperature is rapidly lowered~ After the injection of the parison is complete and the parison tem-perature-conditioned, the core rod platen 140 is retra~ted as neck ring carrier plate 106 is also being retracted car-rying the finished parisons 8 from within the parison mold plate 102 as best shown in FIGURE 1. The preforms are then ready to be transferred to the storage area.
As best shown in FIGURES 1 and 2, the take-out mechanism 201 thrusts into the opened parison mold and the gripper jaws 208 grasp each preform at ~hich time the neck ring assemblles 104 open as previously described The take-out mechanisrn riding on carriage 206 withdraws the parisons allowing the injection mold to close to begin the cycle for forming the next group of preforms.
Simultaneous with the closing of the mold and the 3Q commencement of formation o~ a new set of parisons, the ro-tar~ transfer mechanism 240 as best shown in FIGURE 7 is moved inward transversely by air cylinder 246 on rods 242 and 244. Upon moving forward, the gripper jaws 208 Qn the take-out mechanism holding the parisons permits the parisons to be centered against the stop bar 238 as a result of the neck flange 9 o~ parison 8 being brought into contact with .4 the s~op bar 238 by colle~s 249. This is desirable in order that all of the parisons are exactly even for subsequent gripping by the collets and jaws of the storage plate, la-teral transfer unit and the shuttle jaws as shown in FIGURE
26 where SR-l is the first position of stop rail 238; SR-2 is the second position of the stop rail, i.e., butted against parison flange 9; SPJ is the storage plate jaws; LTJ is the lateral transfer jaw; SMJ is the shuttle mechanism jaw, and BM is the top part of the blow mold. With the parison but-ting up against the stop bar 238, actuator plate 270 simul-taneously contacts all sixteen collet actuators 262 and the collet probe 250 enters the necks of the parisons. Substan-tially simultaneously, the take-out gripper jaws 208 are released as shown in ~IGURE 7 and the collets grip the pre-forms, permitting the preform to be withdrawn by the trans-verse movement of the collets when piston rod 245 of air cylinder 246 is retracted. T~e transverse pla~e 248 is then xotated downward ninety degrees as best shown in FIGURE 8, to place the preforms in position in the storage plate 300 At the time the transverse plate 248 carrying the collets 249 is rotated downward, the jaws 303 of the storage plate are open After the parisons are rotated into the vertical position, the jaws of the storage plate close securing the preforms while the collets are released and retracted, The transverse p:Late is rotated ninety degrees upward into a position for receiving the next group of parisons~
The storage plate 300 after receiving the parisons permits temperature-conditioning of the parisons with heat-conditioning element 350, As shown in ~IGURES 13 and 14 the storage element riding on ~ertical rods 352 can rise upward clearing the bottom 403 of the lateral transfer unit 402 and encompassing the preforms 8 while in the storage plate. As is apparent from the broken-away view in FIGURE
14, the heat-conditionin~ unit is constructed in order that the pockets 351 avoid carrier rod 370.
~ hen the prefo~ms are properly heat~conditioned P~ 4 within the heating pockets, the heating element is lowered clearing the way for the transverse movement of the lateral transfer unit 402. The lateral transfer mechanism as best shown in FIGURES 15 and 16 enters under the storage plate being guided between the rows of parisons with the lateral transfer jaws being open. After the lateral transfer unit is properly positioned, the jaws of the lateral transfer unit are closed and the jaws of the storage plate are opened.
The parisons are withdrawn transversely from under the stor-age plate by large air cylinder 416. The first row of pari-sons are then positioned for acceptance by the shuttle me-chanism 450. The shuttle jaws 454 come in, grasp the first row of preforms, position A of FIGURE 25; and thereafter retract to posi~ion B, depositing the first row of preforms into the open blow molds 502~ Simultaneously, the blow molds close about the preforms while the shuttle jaws are still in place and the lateral transfer unit indexes the second row of parisons into the shuttle position as shown in FIGURE 17~ The shuttle jaws open and extend to the posi-tion C in FIGURE 25 to secure a second set of parisons.Simultaneous with this movement, the blowhead of the blcw mold assembly comes down and the first set of parisons are blown to the finished bottles, The jaws of the shuttle close arQund the second row of preforms and around the fin-ished bottles 608 in the blo~ molds. The blowhead rises, the blow mold opens, and the shuttle mechanism retracts into position D of FIGURE 25 carrying the finished bottles to conVeyor mechanism 600 while positioning the second row of preforms in the blow molds~ Simultaneously the blow mold 30 closes, the third row of parisons are indexed into the shut-tle position as shown in FIGURE 17, and the shuttle returns to position A for the third row of preforms. The cycle is continuously repeated.
Although the improved machine system has been de-scribed usiny a 20~-second cycle designed for the use of PET, the machine system can be modified to accommodate the curing characterlstics of any plastic material. Moreover, although the improved machine system has been described using sixteen preform molds and four blow molds, the ratio can be modified to best suit a given temperature cycle. The ratios can be-any whole number such as 8 to 2; 4 to 1; 9 to 3; 3 to 1, or the like.
Additionally, the machine system and process, since the neck ring is removed from the parison after formation at the parison-forming station of the neck ring finish, permits the complete temperature-conditioning of the neck and shoul-der areas of the parison. Thus, in a system in which the neck ring mechanism is used as a-means of transferring the parison from the parison-forming station to the blow station, it is not possible in view of the heat-transfer characteris-tics of the neck ring to effectively temperature-condition the neck and shoulder areas of the parison. This can lead to defects in the neck and shoulder areas of the final bot-tles. According to the present machine system and prGcess, it is possible to apply heat or remove heat during the pari-son transfer or storage period to and from those and onlythose areas o~ the parison requiring temperature-condition-ing. This temperature-conditioning permits a better transi-tion from the neck finish to the body of the final bottles providing, inter_alia, a better appearance.
~ hough the abilit~ to heat-condition the parison including in select areas is a unique advantage o~ the pre-sently described machine s~stem and process, it is to be understood that it may not be essential, depending upon the total operating conditions, to use a heat conditioning element, If the heat-conditioning element is not emplo~ed, various modifications can be made in both the rotary trans-fer mechanism and in the lateral transfer mechanism, As will be apparent to one skilled in the art) various modifications can be made in the hereinbefore de-scribed m~chine system and process with respect to making improved bottles. The pre~erred embodiments described are not to be construed as a limitation o~ the invention.
Claims (17)
1, In a machine system for manufacturing plastic bottles comprising a plurality of parison-forming stations;
a plurality of blowing stations fewer in number than the number of parison-forming stations; a storage area for hold-ing parisons formed at said parison-forming station, and means for transferring parisons from said parison-forming station to said storage area and from said storage area to said blowing stations; the improvement wherein the storage area includes a storage plate and the transfer means from said storage plate to said blowing stations includes lateral transfer means for receiving said entire plurality of pari-sons from said storage plate and shuttle means for sequen-tially transferring a plurality of parisons but fewer than said entire plurality of parisons from said lateral transfer means to said blowing station,
a plurality of blowing stations fewer in number than the number of parison-forming stations; a storage area for hold-ing parisons formed at said parison-forming station, and means for transferring parisons from said parison-forming station to said storage area and from said storage area to said blowing stations; the improvement wherein the storage area includes a storage plate and the transfer means from said storage plate to said blowing stations includes lateral transfer means for receiving said entire plurality of pari-sons from said storage plate and shuttle means for sequen-tially transferring a plurality of parisons but fewer than said entire plurality of parisons from said lateral transfer means to said blowing station,
2. The machine system of claim 1 wherein said storage plate includes a plurality of openings equal in number to said plurality of said parison-forming stations for simultaneously receiving said plurality of parisons, said openings being arranged in a plurality of rows and being formed by a plurality of jaw sets having closure means for simultaneously opening and closing said jaw sets.
3. The machine system of claim 1 wherein the closure means includes an air cylinder.
4. The machine system or claim 2 wherein said la-teral transfer means includes means for forming a plurality of openings equal in number to said plurality of parison-forming stations, said openings being arranged in rows.
5. The machine system of claim 4 wherein said openings are formed by jaw sets and the jaw sets of each row are individually actuated, whereby the jaw sets of each of said individual rows are independently opened and closed.
6. The machine system of claim 5 wherein said la-teral transfer means further includes means for indexing said transfer means whereby said plurality of rows are in-dependently positioned,
7, The machine system of claim 6 wherein said shuttle means comprises a plurality of openings for receiv-ing parisons spaced apart on longitudinally extending support bars.
8. The machine system of claim 7 wherein said openings are formed by a plurality of jaw sets, said jaw sets being simultaneously opened and closed.
9. The machine system of claim 8 wherein said blow-ing stations include a plurality of blow molds arranged in a row for receiving and blowing parisons and each mold in-cludes a blowhead having a stretch rod, said plurality of blow molds including means for simultaneously opening and closing said molds and means for simultaneously actuating said plurality of blowheads.
10. The machine system of claim 9 wherein said shuttle jaw sets are constructed and arranged to engage a parison neck in said blow molds while the blowheads of said blow molds are in the blowing position.
11, The machine system of claim 10 wherein said plurality of blow molds are splitable into halves and are integral with each other, and include actuating means whereby the two halves of said blow molds are simultaneously moved apart.
12, The machine system of claim 11 wherein said actuating means for said blow molds includes toggle means.
13. The machine system of claim 12 wherein said open-ing and closing of said molds simultaneously lowers said blowheads into actuating position and locks said blowheads down.
14. The machine system of claim 13 wherein said blow molds are in three pieces and include in addition to said split halves a bottom section which is simultaneously moved downward in slideway means by toggle means when said halves of said blow mold are opened.
15. The machine system of claim 14 wherein said blowheads include legs circumscribing said stretch rod.
16. The method of forming plastic bottles comprising the steps of-(1) simultaneously forming a plurality of parisons in a closed mold at a parison-forming station, said mold comprising a plurality of parison-forming cavities and each of said cavities including a neck ring assembly;
(2) opening said mold and simultaneously receiving said plurality of hot parisons with parison gripper means and separating said parisons from said neck ring assembly;
(3) positioning said parisons in a storage area;
(4) repeatedly withdrawing a plurality of said parisons fewer in number than the entire plurality of parisons from said storage area at substantially the blowing temperature of said parisons and transferring said parisons to a blow mold for blowing; and (5) blowing said parisons in said blow mold until said entire plurality of parisons have been blown.
(2) opening said mold and simultaneously receiving said plurality of hot parisons with parison gripper means and separating said parisons from said neck ring assembly;
(3) positioning said parisons in a storage area;
(4) repeatedly withdrawing a plurality of said parisons fewer in number than the entire plurality of parisons from said storage area at substantially the blowing temperature of said parisons and transferring said parisons to a blow mold for blowing; and (5) blowing said parisons in said blow mold until said entire plurality of parisons have been blown.
17. Method of forming a molecularly-oriented plastic bottle comprising the steps of-(1) forming a parison in a closed parison-forming mold, said mold including a neck ring assembly;
(2) opening said mold and removing said parison from said mold including said neck ring assembly while said parison is hot;
(3) temperature-conditioning said parison while free of said neck ring assembly in at least select areas of said parison; and (4) stretching and blowing said parison without cooling said parison substantially below the stretch and blow temperature of said parison after the parison formation.
(2) opening said mold and removing said parison from said mold including said neck ring assembly while said parison is hot;
(3) temperature-conditioning said parison while free of said neck ring assembly in at least select areas of said parison; and (4) stretching and blowing said parison without cooling said parison substantially below the stretch and blow temperature of said parison after the parison formation.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000431694A CA1176014A (en) | 1979-02-21 | 1983-06-30 | Delay stretch and blow machine system |
| CA000460035A CA1204905A (en) | 1979-02-21 | 1984-07-30 | Delay stretch and blow machine system |
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US06/013,417 US4310282A (en) | 1977-06-13 | 1979-02-21 | Delay stretch and blow machine system |
| US013,417 | 1979-02-21 | ||
| CA000344143A CA1151373A (en) | 1979-02-21 | 1980-01-22 | Delay stretch and blow machine system |
| CA000431694A CA1176014A (en) | 1979-02-21 | 1983-06-30 | Delay stretch and blow machine system |
Related Parent Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000344143A Division CA1151373A (en) | 1979-02-21 | 1980-01-22 | Delay stretch and blow machine system |
Related Child Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000460035A Division CA1204905A (en) | 1979-02-21 | 1984-07-30 | Delay stretch and blow machine system |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1176014A true CA1176014A (en) | 1984-10-16 |
Family
ID=27166553
Family Applications (2)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000431694A Expired CA1176014A (en) | 1979-02-21 | 1983-06-30 | Delay stretch and blow machine system |
| CA000460035A Expired CA1204905A (en) | 1979-02-21 | 1984-07-30 | Delay stretch and blow machine system |
Family Applications After (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000460035A Expired CA1204905A (en) | 1979-02-21 | 1984-07-30 | Delay stretch and blow machine system |
Country Status (1)
| Country | Link |
|---|---|
| CA (2) | CA1176014A (en) |
-
1983
- 1983-06-30 CA CA000431694A patent/CA1176014A/en not_active Expired
-
1984
- 1984-07-30 CA CA000460035A patent/CA1204905A/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| CA1204905A (en) | 1986-05-27 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CA1151373A (en) | Delay stretch and blow machine system | |
| CA1098666A (en) | Plastic bottle forming machine with modular design | |
| US4140464A (en) | Machine system for formation of molecularly oriented plastic bottles | |
| EP0001626B1 (en) | Injection blow molding apparatus method | |
| US4261949A (en) | Process for formation of molecularly oriented plastic bottles | |
| US3583031A (en) | Apparatus for blow molding hollow thermoplastic bodies | |
| CA2154826C (en) | Parison molding apparatus and method | |
| CA1311890C (en) | Dual injection mold preform transfer assembly | |
| CA1103868A (en) | Parison pickers with variable spacing | |
| US6217819B1 (en) | Universal single-row and multi-row insert stretch blow molding method and apparatus therefor | |
| US4709803A (en) | Preform transfer mechanism | |
| US5501589A (en) | Injection blow molding apparatus | |
| US6713013B2 (en) | Single-row and multi-row stretch blow molding method and apparatus therefor | |
| US6358038B1 (en) | Injection stretch blow molding machine | |
| US5169705A (en) | Servo electric driven stretch rods for blow molding machine | |
| US4241009A (en) | Parison pickers with variable spacing | |
| US4963086A (en) | Reheat blow molding machine for forming articles from preforms | |
| US4882119A (en) | Method for making partially crystalline biaxially oriented heat set hollow plastic containers | |
| EP0499136A2 (en) | Servo electric driven stretch rods for blow molding machine | |
| CA1176014A (en) | Delay stretch and blow machine system | |
| JPS62216722A (en) | Method and device for molding hollow vessel consisting of plastic material which can be molecular-oriented | |
| US5185163A (en) | Reheat blow molding machine for forming articles from preforms | |
| US4043734A (en) | Apparatus for blow molding plastic container | |
| GB2301308A (en) | Parison moulding including cooling of the parison |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |