CA1328719C - Sequential injection molding machine - Google Patents
Sequential injection molding machineInfo
- Publication number
- CA1328719C CA1328719C CA000616478A CA616478A CA1328719C CA 1328719 C CA1328719 C CA 1328719C CA 000616478 A CA000616478 A CA 000616478A CA 616478 A CA616478 A CA 616478A CA 1328719 C CA1328719 C CA 1328719C
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- mold
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- molds
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- clamping
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- Injection Moulding Of Plastics Or The Like (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
An injection molding machine and method of operation is disclosed having a plurality of accessory arrangements for molding a plurality of piece parts in efficient overlapping time cycle using primary and secondary molten plastic injection units, primary and secondary clamping units, a plurality of injection units in various arrays including molding piece parts in reverse or uniform orientation. In particular, an injection molding machine has a plurality of molding stations arranged in tandem where each station includes at least one mold, each mold comprising a pair of cooperating mold halves, fixed and movable platens supporting the mold halves; a single primary clamping means and a plurality of secondary clamping means for opening and closing the molds in accordance with a plurality of permutations and combinations at the direction of a programmed clamping control means, and a process for opening and closing molds comprises the steps of closing all molds by means of the primary clamping means, clamping the mold halves of each mold individually by the secondary clamping means, connecting the primary clamping means to the molds at all stations by means of a serial connection with secondary clamping means, unclamping a first pair of mold halves at a first mold station, and separating the mold halves at the first station by moving the remaining molds at the remaining stations by means of the primary clamping means and the serial connection.
An injection molding machine and method of operation is disclosed having a plurality of accessory arrangements for molding a plurality of piece parts in efficient overlapping time cycle using primary and secondary molten plastic injection units, primary and secondary clamping units, a plurality of injection units in various arrays including molding piece parts in reverse or uniform orientation. In particular, an injection molding machine has a plurality of molding stations arranged in tandem where each station includes at least one mold, each mold comprising a pair of cooperating mold halves, fixed and movable platens supporting the mold halves; a single primary clamping means and a plurality of secondary clamping means for opening and closing the molds in accordance with a plurality of permutations and combinations at the direction of a programmed clamping control means, and a process for opening and closing molds comprises the steps of closing all molds by means of the primary clamping means, clamping the mold halves of each mold individually by the secondary clamping means, connecting the primary clamping means to the molds at all stations by means of a serial connection with secondary clamping means, unclamping a first pair of mold halves at a first mold station, and separating the mold halves at the first station by moving the remaining molds at the remaining stations by means of the primary clamping means and the serial connection.
Description
~32~7~9 The present invention relates to injection molding machines and relates, in particular, to such machines having the capability of operating a plurality of molds arranged in series. In particular, the invention is concerned with a process for opening and closing molds in an injection molding machine, and an improved clamping cycle.
This Application is a divisional of Canadian Patent Application, Ser. NoO 589,420 filed Jan. 27/89.
The prior art shows injection molding machines having the capability of operating a plurality of molds arranged in series. For example, U.S. Patent No.
3,707,342, issued to A. Lohman on December 26, 1972 ;
shows two molds spaced apart in tandem with a dual noz~le injection unit positioned therebetween to fill the two molds alternately. No provision is made for separate means to stuff the molds.
U.S. Patent No. 3,898,030, issued August 5, 1975 to T.G. sishop~ entitled Injection-Mold Clamping Unit Having Alternately Ejecting Die Assemblies, describes that latches 80A and 80B are used to couple separable mold halves 56A and 58A whereby single clamping and ejection units are used for both molds.
U.S. Patent No. Re 28,721, reissued to J.J.
Farrell on February 24, 1976, entitled Time Saver Plastic Draw-Back Valve Assembly, describes a primary reciprocating-screw -1- ~ :.' ~1 ' i32871~ ~7-423 injection unit 12 and an auxiliary injection piston 50 with a valve 52 for divertinq molten plastic 10w from t~e primary unit to the secondary unit thereby isolatinq the primar~ unit and permittin~ the secondary unit to "stu~" mold 32.
O~her pertinent machine patents include PCT
Publication No. W0 86/011~6, dated February 26, 1986 and We~t German Patent No. ~428780, da~ed Marc~ 13, 1986.
In addition, the prior art shows stack and sandwiah mold arran~ements wherein the molfl cavity plate~ are digposed ~ack to back separated by an inte~ral hot runner. ~epxeeentative of staak mold arran~emen~s are U..S. Patent ~08. 3,7~3,040, 3,973,892 an~ 4,400,341.
Stack or sandwic~ mold arrangementfi are well known in the artl however, their draw backs lnaluae a le~ than optimum operat~nq cycle and lack o~ versati~ity ln component~.
~ dditional publications of interest are U.S. Patent No. ~,752,207, issued June 21, 19~8 to ~aaden, including a related brochure entitled "~TU~RE - Twin~Statlon In~ection-Mouldinq Machlne3" an~ a brochure b~ Stork Plastics Machinery entitled "Stork rJ-Type In~ection M~uldin~ Mach~ne".
, ~ 32 8~1 9 ~7-423 The '207 patent and related Stubbe brochure (publis~ed October 1986) show a ~oose neck connection between a plastic injection uni.t and a distributor carried by a movable platen.
The Stork brochure ~publi~hed on or about 1985) shows an injection unit disposed perpendicular to the mold clamp unit axis.
Moreover, there i9 a disadvantaqe in combini.n~ a hot runner wi.th mold element~ as a sin~le piece part.
Such an arrangement necessita~es replacement o a complete multiple elem~nt mold and ho~ runner as a unit when one wishes to ~han~e molds. Whereas when ~he mold elements are separable from the hot runner ~ystem, i~ ls merely necessary ~o remove mold elements while ~he hot runner remains a machine fixturq.
U.S. Patent ~lo. 4,539,171 ~o ~orensen is al~o of interest. In the '171 patent, ~hermoplastic material i8 transferred from an injection unit to a sandwich mold by means of a so-called snorkel 30 and a cooperatin~ noz~le 16. The snorkel and nozzle make a connection to provide a conduit for thermoplastic material. The snorkel and nozzle move relative to another alon~ a common axis :~
which i~ parallel to an~ spaced ~rom central axi~ 13 alon~ which clampinq platens 10 an~ 11 rec~procata.
.
132~7~
In accordance with one aspect of the invention there is provided in an injection molding machine having a plurality of molding stations arranged in tandem where each station includes at least one mold, each mold comprising a pair of cooperating mold halves, fixed and movable platens supporting the mold halves, a single primary clamping means and a plurality of secondary clamping means for opening and closing the molds in accordance with a plurality of permutations and combinations at the direction of a programmed clamping control means, a process for opening and closing molds comprising the steps of closing all molds by means of the primary clamping means, clamping the mold halves of each mold individually by the secondary clamping means, connecting the primary clamping means to the molds at all stations by means of a serial connection with secondary clamping means, unclamping a f irst pair of mold halves at a f irst mold station, and separating the mold halves at the first station by moving the remaining molds at the remaining stations by means of the primary clamping means and the serial connection.
In accordance with another aspect of the invention there is provided in a method of molding articles sequentially at two different molding stations each having a mold where both stations are within a single unitary injection molding machine, the maahine _4_ , - ,.
-" 172~719 being operable to inject material at a primary injection pressure and at a secondary injection pressure, an improved clamping cycle comprising the steps of arranging the molds of two molding stations A
and B in series, clamping the molds of both stations A
and B to oppose a primary injection pressure, clamping the mold at station B to oppose a secondary injection pressure, injecting molten plastic into the mold at station B solely, releasing the primary injection pressure on the molds of both stations A and B, again clamping the molds of both stations A and s to oppose the primary injection pressure, again clamping the mold at station A to oppose the secondary injection pressure, injecting molten plastic into the mold at station A solely, and again releasing the primary injection pressure on the molds of both stations A and B whereby the molds at stations A and B are clamped under secondary injection pressure independently.
A further feature of the invention is to provide a primary clamping system operable to clamp all mold stations simultaneously. A single primary clamp means cooperating with and making a series connection with a plurality of secondary clamp means is operable in response to a clamp control unit to open and close molds at a plurality of tandemly arranged mold stations in accord with various permutations and combinations.
-" ~328719 It is a further feature of the invention to provide an independent secondary clamping system operable to clamp platens of a given mold station directly and selectively or, in the alternative, operable to clamp mold halves of said given station directly and selectively.
It is a further feature of the invention to mount secondary clamps directly upon the mold platens.
A feature of this invention is a novel molding sequence in which a part molded at a station A, for example, which is serviced by a primary and a secondary injection means may be of entirely different size and structural complexity than another part molded at a station B. In accordance with this feature, filling and stuffing of the mold at station B may be accomplished sequentially by a single injection means.
A still further feature of the invention is that two parts requiring generally equal cooling periods may be molded at two tandemly arranged stations using a single primary clamp means. The single primary clamp means acting upon two stations in the same time interval that would be required if the parts were -molded successively at the two mold stations utilizing primary and secondary clamp means.
1~28719 In contrast to the above prior art disclosures, there is disclosed herein an injection molding machine having a plurality of molding s-tations with a plurality of machine accessories arranged in various combinations developing a sequence of operations calculated to reduce molding cycle time per part particularly when molding large parts, such as large containers or autobody parts.
There is particularly described herein an injection molding machine which enables the mold assemblies to be operable independently of each other and to be readily separable from the machine.
A further feature disclosed herein is the provision of a plurality of mold stations arranged in series and separated by a discrete, central, movable machine platen.
A further feature disclosed herein is the provision of structure for transferring molding compound from an injection unit to a manlfold distributor block along a path which is perpendicular to the clamping axis or the longitudinal machine axis.
A still further feature disclosed herein is the provision of seal means for sealing the injection unit nozzle to the distributor block orifice along an axis I which is perpendicular to the clamping axis.
I
-~32~719 A further feature disclosed herein is the incorpora-tion in the central movable platen of a distributor communicating with whatever mold halves may be attached to the central platen.
' A further feature disclosed herein is the provision of a check valve in the distributor block to prevent leakage of resin when the injection unit nozzle is not in sealing contact with the distributor block orifice.
A further feature disclosed herein is the provision of a central movable platen with individual manifold sections on opposite sides of the platen operable to feed moldable resin to mold halves carried by the central platen under the control of valve means positioned upstream of the central platen. The central movable platen may be cored for cooling and the manifold sections isolated from the platen by an insulating air gap.
A further feature disclosed herein is the ;
provision of valve means in the manifold distributor block operable to place the injection unit and/or a packing unit in communication with the individual manifolds, selectively.
A further feature disclosed herein is the provision of power means for effecting and maintaining the seal between the manifold distributor block and the ~ `
13 2 8 r~
, ~ , injection unit nozzle where the power means operates along a path which is perpendicular to the mold clamping axis.
A further feature disclosed herein is the provision of a plurality of mold stations arranged in series and separated by a discrete, central, movable machine platen.
A still further feature disclosed herein is the feeding of molten plastic into a plurality of individual mold cavities at different, serially arranged mold stations utilizing a single primary injection means and one or more secondary injection means to fill and pack (stuff) each said mold cavity in sequence thereby increasing overall productivity of individual molds.
A further feature disclosed herein is the use of primary injection means dually as a mold cavity ~ ;~
"filler" and a mold cavity "stuffer".
~A further feature disclosed herein is a novel sequencing system for utilizing primary and secondary ~
,,:
injection means to inject molten plastic into a ~-plurality of mold stations clamped by a single, primary clamping means, where the primary injection means performs both, a mold filling and stuffing function at one station 1~ ~
: ' :
. , ~3~871,9 A further feature disclosed herein is the provision of an injection molding machine in which one or more primary injection means are mounted on a fixed or movable platen with track means facilitating motion of the units, to and fro, along the longitudinal axis (x axis) of the machine.
A still further feature disclosed herein is the incorporation, into a multi-station injection molding machine, of a parts removal device or robot which is operable to remove parts molded in reverse or in identical orientation at each station.
A further feature disclosed herein is the provision of a secondary injection means mounted on a movable platen whose design lends itself to a wide -variety of mounting locations on said movable platen, i.e. top, side or bottom of said movable platen.
A further feature disclosed herein is the provision of an injection molding machine on a single rame means comprising at least two injection means and at least four mold stations arranged in series.
-9a- -~7-423 132~7~
An injection molding machine embracing ~eature~
described herein includes, in one comblnation or another, a main frame, fixed and movable platens to support mold halves and primary and secondary clamp means. The secondary clamp mean~ are usually attached to the mold platens, however, i~ nece~sary they may also be mounted directly on mold halves that are attached to the pla~ens.
A distributing manifola iB incorporated in a central movahle platen includin~ valve means or ~irectin~ molten plas~ic to oppose~ mola s~atlon. The manifoLd includes a connec~ion to a primary injection means and to a seconflary in~eat~on means with appropria~e valve means ~or controllin~ flow ~rom the primary injection means.
In an alternative embodiment o~ the machine, the primary in~ection means is pro~rammed to melt su~icient plastic to fill two molds. A irst mold is then filled by the primary injection mean~ and stuffe~ by a secondary in~ection means. Next, molten plastic flow i~ ~;
directed to a second mold station where the filling of the molfl as well as the ~tu~fin~ Btep i8 performed solely by the primary in~ection mean~. In thl~
embodiment the clampin~ ~unction may be 601ely by the ~3~7~9 87-~23 . ..
primary clamp means or by the primary clamp means in combination with ~econdary clamps, depending upon size, configuration and relative coolinq rates o~ the respective molded parts.
Further, the machine includes ejection means and a parts remover (robot) which operates on rec~ilinear coordinates to move from moldinq station to molding station along a ~irst axi3 and into and ou~ of an open mold alon~ a ~econ~ axi 8 .
Product may be molded in the same or in rever~e orientation with appropriate modification of tlle part3 remover and the flow path of the molten plastic.
In rever~e orientation, the remover hea~3 carries flual "plck up" elements, while product molded in same orientation is ~rasped by a remover head wlth a ~in~le pick up.
In certain ~ituatlon~, the ~ize and compLexlty o~
th~ mol~ed parts require the use of a plurality o~
primary injection means adapted to cooperate with a plurality of secondary injection means to insure complete ~illing an~ stuf~ing the corresponding mold cavity in a qiven mold station.
A ~urther embodiment o~ the mac~in0 takes the orm of a double capacity unit. In thi~ arrangement, there ` ~
~328719 87-423 are four molding -qtations, two primary injection means and two central platen~, each incorporating a ~istributor.
o~her features an~ advantages o~ the preisent invention wi.ll become more apparent from an examination of the s~cceeding speci~icatlon when read in conjunction with the appended drawings, in which:
.
~RIF,F DESCRIPTION OF THE DRAWI~C~S
Flg. 1 showici A side view o~ a typical lay out of - t~e sequential molding machine of thie pre~ent invention with the distributor block bro~en away for clarity:
Fig. 2 is a view aimilar to Fig. 1 showing the oppoeite moldin~ station open with the molded part ~ .
poised for removal:
Fig. 3 is an additional side ~iew ~howing both mold stations in the closed condition with primary anfl :~
secondary clamp mean~i In operation:
- Fiq. 4 is a side of the machine with the moldefl .
part~i remover or robot in an open mold retrieving a part;
Fig. 5 is a top plan view of the illustration of Fi~
Fig. 6 is similar to Fi~. 5 showing the robot in the opposite moldinq stationJ
13287~9 87-~23 , , Fig. 7 i~ a plot of the machine sequence o~
operation charti.ng the position of the various mac~ine accessories against the step by step generation o~ the molded parts Pig~. 8, 9 and 10 show an alternative arrangement of primary and secondary injection means ~erving two molding stations;
Fi~. ].1 is a plan view of an injection molfling machine with an alternative ~econdary or parting line clamp ~tructure, Fi~. 12 is a schematic illustration of details of the structure and moun~inq mean~ o t~e alternative . seconaary clamp o~ Flg. 11;
¦ Fi~. 13 is a plan view of a ma~hine modification in w~ich a plurality of primary injection means are :
utilized in combination with a plurali~y o~ di~tributor block~ anA corre~ponding aecondary in~ection mean~
Fig. 14 is a side view of an additional machine modi~ication showing double sets o~ primary and secondary injection means and robots ~ervicing ~our mold stationss Fi~. 15 is a char~ fletailing the opera~ing sequence o~ the machine o~ Fiq. 14;
. -13~
~: ' .
~7-423 ~328'~19 Fi~. 16 i.s a side view o an altexnative machine arrangement facilitating molding piece parts in the same physical orientation using a single primary in~ection means Fi~. 17 is similar to Fiq. 16 modified to use two primary injection units;
Fi~. 18 is a cycle chart for the Fi~ 18 modi~icationt Fig. 19 is a plan view o a modi~led molding machine with por~ions broken away to illustrate an al~ernative manifold structure, Fiq. 20 is a plan view of a portion of Fiq. 19, enlarged, showinq the hot runner sy~tem, the in~ection .
unit ~extruder), the injection unit nozzle clamp means and mold halvesS
Fig. 21 iB a view similar to Fig. 20 showinq the in~ection untt in po~ition to ~upply mol~able material ~. :
to the hot runner 6ystem with the injection unit nozzle clamped to the hot runner ~ystem, Flg. 2~ is an elevational view of the ri~ht side of Fiq. ~1 showing the valve means for switclling molding material to manifold sections, the nozzle clamping means and a packing cylin~er or ~tuffer, and, Fi~. 23 ls a ~ectlonal view, enlarqed, a~ viewed in the plane of the line 5-5 o Fiq. 20 and in the ~7 - a~2 3 ~328~19 direction o~ the arrows, s~owing the seal between the nozzle and the manifold distributor block and showing the valve means.
DE~AILED DESCRIPTION OF THE PREFER~D EMBODI~EN~
Referring ~o Figs. 1, 2 and 3, a basic embodiment of the injection moldinq machine o~ the present invention is disclosed comprising molding stations A and B havin~ es~ential aacessories deining a primary clamp section 11, a ~econflary clamp sectiort 12, a primary molten plastic injection section 13 anfl a secondary injection section 14. Either ~he primary and/or 3econdary injection unit may be o~ the reciprocating screw type or pi_ton type.
Molds 16 and 17, frequen~ly of diferent configura~ions, comprise mol~ halves 18 and 19 and 21 and 22, respectively.
Mold halves 19 and 21 are mounted on central movable platen 26 and halves 18 and 22 are mounted on movable platen 24 ana ~ixed platen 27, respectively.
Platens 23 and 27, fixed to the machine frame 31, upport tie bars 28 and 29 in the usual and cu~tomary ashi on .
' - --].5--i ~7-~23 132~719 Pla~en 24 i9 connected to primaxy clamping pi~ton 32 and is reciprocated thereby sliding on tie b~rs 28 and 29.
~, Central platen 26 is also movable on tie bars 28 ana 29 and i~ releasably connected to movable platen 24 and fixe~ platen 27 by ~econdary clamping mean0 12 in a manner which will be explained in qreater ~etail as this :' ... .
specification proceeds.
Machine section 14 includes a di~tribution block 33 incorporated in platen 26, wi~h heating ~lemente 34, ~. molten plastic supply channel 36 and sel~ctor valve 37 ¦ ~~or diverting compound ~low from station A to ~tation B
and vice ver~a.
~ he Ai~tributor blocX 33 terminates in a cylinder ~8 ~aving a pis~on 39 an~ a reservoir 41.
A ~econ~ c~annel 42, adapted to make a connection with a reaiprocatin~ primary in jection ~ection 13, a~ i8 most apparent in Fi~. 2, include6 a shut off valve 42 for cu~ting off molten plas~ic ~low from the primary injection means.
With the plston 39 in the retracted po~ition, a~
shown in Fig. 1, the molten pla3tic advanced by the ~i injection section 13 opera~e3 to ~ill the mold cavity to which 0elector valv- 37 is ~et ~tation B in ~ and ~imultaneously ills reservoir or accumulator 41. ~1pon ~:
~ ' ' ~ -16-87-~23 ~32871~
closure o~ ~hut of valve 43, i~olating the injection section 13, actuati,on of the piston 39 i9 operable to "stuf~" t~e mold cavity to which molten plastic was inltially directed.
~ bviously the reservoir can be reestablished and rechar~ed upon retraction of the piston 39 in preparation to char~e the opposite mold cavity.
Typically, the injection section 13 include~ a plasticizing-i.n~ection unit re~erred to in the ar~ a~ a reciprocating-screw extruder.
Fi~s. 4, 5 and 6 are similar to Flg~. 1, 2 and 3 and ~how de~aila o~ one em~odiment o~ the ~econdary clamp means and the structure and operation o~ the ~
molded parts removal unit or robot. , Referrinq to Fig. 4, the parts removal-unit operate~ automa~iaally in tlmed ~quencei in rohot ~ -~ashion, and includes a first Leq 44 which reciprocates ~;
under control of power unit 46 alon~ the lon~itudinal axis (x axis) o~ the machine guided by a track (not ~ ' shown). ~he power unit 46 i8 supported by ~ixe~ platen 27. `
When the part removal head 48 is in register with an open mold, such as t~e open mold at station A ~n Fiq.
4, a second ley 4~ i9 actuated by suitable power mean~
to advance the head alon~ a eeaond axis (~ axis) into ' ~
~7-~23 ~28719 re~ister with finished part P. The part is then ejeated from core 51 by ejector pins 52, in well known fa~hion, and picked up by the head.
The head 48 is provided with a source of vacuum and a valve operable to direc~ vacuum to the part side of the head where upon the part P is grasped and drawn away from the core by the head. The heafl i6 retracted automatically and the part P released to an appropriate container (not shown) for packa~ing or further processing, as the ca~e may be.
Fig~. 5 and 6 are top plan views o~ the illu~tration of Fig. 4 anfl show details and operation o~
one embodiment of the secondary clamp sea~ion indlcated generally by the re~erence numeral 12.
Pairs o~ opposed arms S3 and 54, ixed to central platen 26, are formed with notche~ 56 and 57 and cam ~ace~ 5~ and 59. The notche~ are enga~sfl by ~og~ or lu~s 61 and 62 having mating cam faces 63 and 64. The lu~s 61 anfl 62, operable to reciprocate in timefl sequence un~er the control of pl~ton-cylinder ~ssemblies 66 and 67, are mounted on the movable platen 24 and fixed platen 27, xespectively.
As mold halves of a given mold station approach their closed po~ition, the lu~s move into matlng notche~
..
. . .
~7-~23 ~328719 and the mating cam faces engage one another to drive the mold halves into ti~ht face to face contact holdin~ the ~old halves sealea during cavity stuffing and subsequent cooling period independently of the primary clamp means in a manner and according to an operating ~equence set forth in the cycle chart of Fi~. 7.
Fiq. 6 shows the part removal head 48 in place in the open mold at ~tation s poisefl to retract ~rom the mold to transfer part P out of ~he machine.
In thi~ po~ition t~e vac~um o~ the head 48 ha~ ~een diverted fro~ the ri~ht side of the head to the left side of the head as viewed in Fiq. 6 to accompli~h the part pick up at station s.
Referrin~ in de~ail to Fig. 7, a plot showing a typical molding cycle of the machine of Figs. 1 ~hrough 6 is lai~ out coordinately where t~e y axis i8 a ~che~ule of sequenti~l positions o~ the variou~ m~chin~
components or accessories for stations A and B, and the x axis i8 a schedule of the proqres~ of the part through the molding ~teps.
The chart is read in the following fashion:
startin~ at the upper left hand corner at the polnt in~icatea by the letter S, one 'IpiC~8 Up'l the moldinq cycle by notin~ the small c~rcle~ extendin~ alon~ t~e y axis w~ich indica~e that primary clamp 11 is open, -19~
1 .
87-~23 13287~9 injection section 13 is back (to the right in Fig. 4), the injection section 13 i.6 plasticizing, shut o valve ~3 is closed, secondary injecti.on section 1~ (stu~fer piston 38) is retracte~, selector valve 37 i~ open to station ~, secondary clamp section 12 is clamplng R tation A, secondary clamp 12 at station B is free (open), ejector pins 52 are retracted at station A, ejector pins 52 are forward tejecting) at station B, robot or pick up hea~ 48 ha~ moved alon~ machine x axi~
to station B and along t~e z axis into the mold at ~tation ~.
~ eferring to the point x at the lower lef~ corner o~ the chart of ~iq. 7, i~ i~ apparent when the variou~
mac~ine elements are in the po~ition~ ~uat indicated by "reading" the char~ a molfled part is coolin~ in it~ mold at ~tation A and ~he robo~ or pick up head 48 i~
positioned in ~e open moLd at station B.
The chart is read in the manner de~cribed incrementally from le~t to right, the machine having produced two part~ P upon arriving at end E of a complete cycle.
Referring now to Fi~s. 8, 9 and 10, an alternative embodiment of the primary and seconaary injection means i~ ~isclosed schematically. In thi~ arrangement molding stations A and B are serviced by an in~sction unit 68 ~328719 87-~23 and secondary injection unit 69. A selector valve 71, (qhown as a two way valve but which ma~ be a three way valve) disposed in ~istributor block 72 within platen 70, i8 operable to ~ivert the flow of molten plastic from injection unit 68 to the mold at station B as indicated schematically in Fi~. 9 or to the mol~ at~;
s~ation A as indicat~d sc~ematically in Fi~. 10. Thus, ~ .
operation of the injec-tion unit in the Fi~. 9 :~
arrang~ment delivers molten plastic simultaneously to the mold o~ station B an~ to the seaon~ary in~ection unit 69. At ~he appropriate interval ~elector valve 71 : :
directs the mol~en plastic to mol~ station A wllile in~ection continues into station B rom the 6econdary in~ection unit, The signlflcance o~ this arr~n~ement i~
that (1) the primary in~ection unit is pro~rammed to prepare sufficient plastic to satisfy the molas of both .
mold stations A and Bt (2) the s~condary in~ection unit 69 completes injection into the mold at ~tation B a~ter ~ ~
selector valve 71 shifts the flow of plastic to station ~ :
A; ~3) molten plastic i5 delivered directly to ~tation A
~rom the primary injection unit to comPlete the :~
in~ection, whereby either the primary and/or secondary unit may serve as a stuffer. For example, as a variation of this embodiment one may also stu~f station A with ~econdary in~ection unit 69 wi~h appropriate valving,.
. -21-~; - . -. ~ :
13287~9 Either the primary or ~econdary in~ection uni~s may be of the reciprocating screw type or the piston type~
Injection pressure of molten plastic into a mold cavity to fill a mold cavity is fre~uently of a level ranging from 15,000 to 21,000 psi and injection pressure to "hold or stuf" the cavity to com~ensate or shrinkage is frequently of the order of 6,000 psi.
~ he~e pre~ure levels can be develope~ by prlmaxy and/or secondary in~ection means.
When piece part~ molfled at ~tations A and B have substantia]ly uniform or equal cooling period~, secondary clamping mean~ (parting line clamps) can be eliminated and the molds of sta~ion A and B are held clamped by the primary clamping unit and both molds are opened simultaneou~ly.
In situation~ where the cooling periods are unequal it is ne~e~sary to u~e part~ng line clamps in ad~ition to primary clamp.
Referring now to Fig~. ll and I2, an alternatlve design for a secondary clampin~ unit i~ di~losed wherein partin~ line clamp elements 73 and 74 are shown mounted on mold halves 75 as at 76 shown in Fi~s. 11 and 12. The units at station A and s~ati.on ~ are of iden~ical structure. There~ore, only one modi~ie~
seoondary clamping unit will he described~
.. ,: :: - . -~ ~7-~23 ~287~9 The clamp elements 73 and 74 are opera~ed by a pi~ton-cylinder arran~ement 77 on opposite side6 of a mold station such as is shown at s~ations A and B in Fig. 11. Matinq mold halves are ~ormed with eut out~ or :
recesses 81 and 82 fitted with hardened inserts 83 and 84 secured to mold halves by bol ts 87 and 88. Each insert is formed with a taper matin~ with a ~-corresponding taper on the complementary elamps 73-74.
Actuation of the e~linder unit 77 moves the clamps on opposite sides o~ the moLd~ along a piston rod 86 (fixed to a mold half as at 76) ~rom a retraete~ posi~ion of Fig. 12 to an operatinq position shown ln Fi~. 11 driving the ~old halves into fAee to faee contaet under very high compressive stress.
~ote that the parting line elamp ~truatur~ of Figs. ;~
11 and 12 i6 moun~ed directly on the mold halves and operates directly on the mol~ halves, in contrast to the seeondary clamp strueture described previously whicll i9 mounted on the mold platens and operates direetly on the mold platens.
Obviously, any of a number of arrangements may be devised in mounting the seeondary clampin~ arrangement on the mold halves as engineering and other design eonsiderations dletate.
.
, ~ .,.
' 87-~23 ` 132~719 I Referring to Fig. 13, a ~urther alternative '~ embodiment of the injection molding machine is disclosea wherein the open mold configuration at station B
represents a large, complex part. In order to insure adequate flllin~ and stu~fin~, a machine modification is arranged wherein a plurality of primary injection units ~1, 92 and 93 are mounted on the top of fixed platen 94. Suitable tracks 96 are provided for advancin~ tl~e injection unit~ to and ~ro to make appropriate connection with matin~ ~econdary in jection units ox ~tuf~ers 97, 98 and 99 incorpora~ed in a central movable ~ platen 101. Thus, in operation ~he primary injection .' unit~ and cooperating ~tu~er units are operable individually or collectively in various combinat~ons and permutation~ a~ de~ign complexi~y o~ the molded part~
aictat~ .
Obviou~ly, the po~ition and number of the primary injection and cooperating stuffer unit~ is a matter of choice con~istent with part retrieval, overall length o~
machine, ~loor space and so ~orth.
Fig. 14 illustrates a double capacity ~achine in which there are four molding stations A, B, ~ and D, two oppo~ed primary in~ection extruder3 10~ and 103 with ~wo central mold platens 104 and 106 each incorporatin~ a secondary extru~ion unit~ or stuX~ers 107 and 108, in .~
87-~23 ~L32871~ ~
the fashion and for the purpo~e previously described, for servicing mold stations ~ and C on the left and mold stations B and A on the right, respecti~e]y. ~he reference numerals ]09 and 111 designate mold part removal units or robot~. Naturally, each mold station could have a plurality of molds as required.
Hereagain, the location of primary injecting units i8 a ma~tex of ~e~ign choice based on machine ~ize lim~'tations and available operating ~pace.
~ he machine con~i~uration o~ Fi~. 14 show~ the mold~ open at stations A and D while the molds at station~ R and C are closed.
This confiquration is developed in the following ~ a gh i on .
I Assume tha~ the primary clamping means actuated by ~-piston 32 has moved all movable platens 24, 104, 25 and lOfi to the r~ht a~ainst stationary platen 27 clo~lng all molds at stat1ons A, a, C an~ D with all secondary clamps 12-12 latched.
11pon an appropriate signal from the clamp control ~Figure 5), the secondary clamp 12 at ~tation A i~
relea~e~ while the secondary clamp~ 12 a~ s~ation~ B, C
and D remain latched.
~2~719 The piston 32 i~ ordered to move to the left. This occurrence opens ~he mold at ~tation A and dog 117 secured to movable platen 25 moves ~rom the da~hed line position to the solid line position to abut stop 118.
Contact between the dog 117 and stop 11~ stop~
movable platen 106 in the position shown in Fig. 14 and blocks further separation of mold halves at station A.
Upon the occurrence o~ t~e above-noted abutment and in timefl se~uence, the secondary clamp at station D i8 . . :
unlatched 80 that upon continued motion of the piAton 32 to the left the mold at station D opens to complete development of the mold layout shown in Fiq. 14, i.e.
molds at Rtation~ A and ~ are open and mol~s at station~
B and C remain clo~e~ and clamped.
Aqain starting from a closed mold position at , stations A, B, C and D, ~he molds at station~ ~ an~ C
are openefl in similar fashion in response to the appropriate si~nals ~rom the clamp control unit.
Fig. 15 is an operating schedule showing the sequential positions o~ the various machine accessories as the double capacity unit o~ Fi~. 14 operates to produce ~our molded parts per cycle.
Fig. 16 shows a machine arrangement in which a single primary injection unit i5 utilized to mold parts at ~tations A and B where each part i8 molded in th~
13287~
same physical and ~patial orientation. Si~niicantly, in this arrangement, the robot head require~ only a single pick up unit in that each mold part iB graaped while dlsposed in t~e same orientation.
In this machine configuration a segment of the molten pla~tic flow channel leading to ~ta~ion B i~
carried by and reciprocates with the central platen 104 and is separa~le ~rom ~he flow channel serv~ng station A
as ~hown by the re~erence numeral 100. The ~low channels opera~e to ~upply the mold at ~tation B when valve~ 112 and 113 are open and ~alve 114 ia alosed.
Ater injection and suitable holdin~ at station B valves . and 113 are clos~d, valve 114 is opened and molten plastic i~ injected into the mold a~ sta~ion A at the ¦ appropriate time in ~he molding cycle. In order to I ~acilitate ~his arrangement, a conical cut out 116 1 j ~ormed in the stationary platen 119.
¦ Dependinq, ~or example, upon the s~milarity of molded parts anfl cooling time required, use of a ~econdary injection unit or stuffer i~ optional.
Correspondin~ly, u~e oE secondary clamp units iB al80 an optional acces~ory. The necess~ty ~or secondary clampin~ unit~ depends primarily on ths relative cooling rate~ o~ the part~ m~lde~ at each ~ation.
1` .
:,; , .
~328719 a7-~23 Fig. 17 shows a modification of the arran~ement o Fig. 16 in which two primary injection units are utilized, one ~ervicin~ molding station A and the another servicing station B. In this arrangement, stuffer unit~ are unnecessary in that the primary injection units act dually to perform the mold filling and mold ~tufing function.
Fig. 18 i~ a chart of the molding cycle of Fi~. 17 indicating the various posi~ions of maahine accessories fluring the course of moldin~, coolin~ and e~ecting piece parts ~rom stations A and B ~equentially.
When using more than one injec~ion means, ~iferent resins may be injec~ed into ~ eren~ mold aavities or di~erent resins may be coinjected in the ~ame mold cavity to gain a layered waLl ~ruature.
DE S CR I PT I O N OF T HE ALTE R NAT I VE EM BOD I M ENT
Referring now to Figs. 19-23, a modified in~ection moldin~ mac~ine indicated ~enerally by the reference numeral 111 includes fixed platens 112 and 113, carried by a base frame supporting pairs of tie rods 116-116 and 117-117 in the usual and customary ~ashion. A movable oentral pla~en, in~icated generaLly at P, incorporating a hot runner ~y~tem compri3es a manlfold distributor ..
~a28719 block 120, moldable material switching valve means 121, manifold mean~ de~ining manifold section5 122 and 123, and mold halves 124 and 126 supported by said central platen Central platen P is movable in coo~eration wit~
movakle platen 127 to open and close mold hal~es at mold stations indicated at A and B to mold articles, such as At C.
The clamps 128, 129, 131 and 132 operate ~o ~eal and maintain close con~act between mold halves durinq molding in controllefl ~eq~ence.
Note that manifold section~ 122 and 123 s~raddle and are supported removably by movable central platen 136.
Except ~or suitable fastenlng means and ~pacer~
~not shown), the manifold sectlon~ 122 and 123 are isolated from the central platen 136 by an insulatinq air gap indicated by the reference numeral lOS.
Frequent~y, it is desirabla to includè cooling coils in the central platen 136 to prevent ove~eatin~ ;;
and attendant expansion o~ the platen leading to siezing t~ the tie rods 116-116 and 117-117.
Cooling of the central platen 136 in combina~ion with the insulating air gap 105 protects the manifold sections 122 and 123 from overheating.
r~'" ~
87-~23 ~32g71~
Mold ha].ves 124 and 126 are also supported by ~he central platen 136 and the manifold section~ 122 and 123 are sealed against respective-mold halves 124 and 126 about the periphery o~ mold openings 106 by seaL means defining a raised annulus or boss as indica~ed by the reference numerals 100 and 101.
Mani~olfl dis~ributor block 120, connected ~o the central plat~n 36, include~ molding material ~witc~ing valve 121 and provide~ ~upport for an injection unit nozzle clampin~ mean~ in~icated generally by the ~e~erence numeral 142.
An injection unit in the o~m of an extruder 143, movably ~upporte~ b~ means (not shown), i8 movable from the po~ition shown in Fig. 20 to an in~ection position indicated in Fi~. 21, alon~ a Fath or axi~ indicated by the reference nume~al 144. The axis 144 is generally parallel to the injection mol~ing machine axis (mol~
clamping axis~ indicated by the reference numeral 146.
When the injection unit 143 is in the in~ection position (Fi~. 21), nozzle 147 i~ aligned with and commUnicates wit~ ori~ice 1~8 o~ manifold di~tributor bloclc 120.
A seal, indicated at S~ ig. 23~, is-e~fected by the contact hetween 6urface 149 o~ mani~old di3~rlbutor bloclc in~ert 151 and sur~ace 152 of noz le insert 153.
.
.,.,: - ~ . : i i. . : ~ . ., ` : : : : . . . .
87-~23 ~ he seal i~ maintained by no~zle clamping means 142 defining, in this embodiment of the invention, cylinder 154 with cooperating piston 156 secured to,the manifold ~istributor block 120 by rods 157. The nozzle clamping means acts alon~ axis 160, whlch is perpendicular to machine or clamping axis 14~.
Switching valve means 121, upstream of the manifol~
mean3, defining a spool valve i8 operatefl in cyclic fashion in ~ynchronism with ~he molding cycLe ~o switch moldable material to appropriate maniold sea~ion 122 and 123 via condults 133 and 13~ (Fi~. 23). The 8pool valve 121 is rec~proaated by valve opera~ng ayllnder ~ -159 (Fi~. 22), a~ indicated by the arrow 161 oP Fiq. 23.
Ball clleck valve 162 i~ provided in moldable material flow path 163 to prevent leakage when the nozzle i~ unalamped and the seal between the no~le and ~:
the manifold di~tributor block i~ broken.
A stu~fer or packer unit 164 is located upstream o the spool valve 121 and communicates with the flow path 163 via conduit 16fi. ~:
I~ is anticipated ~hat the ~troke of the in~ection ;
unit 143 in moving ~rom the position o~ Fiq. 20 to the injectlon position of Fi.g. ?.1 will vary from one molding set-up to another dependinq upon the "buil~ up" or ~ thickne~s of the mold halve~. ~
:: ' 1;'''' .. , ,,.,.,, "` . .' .. ''~ ; ' . ' ' ' ~32871~
That is, the injec~ion poi3ition will vary along the machine axis depending upon ~he dimensions o the mold halves in the closed position measured alon~ the lon~itudinal or clamping axiis o~ the machine.
The stroke o~ the injection unit is also advanta~eous in that it provides access for a robot or other automatia molded article retrieval device to enter open mold halve~i to ~rasp and remove a mold~A ~r~icle C.
It iq ~o be understood that the invention i~ not limited to the illustrations described and shown hereln, whiah are deemed to be merely illustrative of the best modes of carrying out the invention, and which are susceptible of modificat~on of form, i~ize, arrangement o parts anA detall~ o~ ope*atlon. The invention rather is lntende~ to encompass all such modi~ication~ w~lch are wlthin it~ spirit and scope as defined by ~he claims.
This Application is a divisional of Canadian Patent Application, Ser. NoO 589,420 filed Jan. 27/89.
The prior art shows injection molding machines having the capability of operating a plurality of molds arranged in series. For example, U.S. Patent No.
3,707,342, issued to A. Lohman on December 26, 1972 ;
shows two molds spaced apart in tandem with a dual noz~le injection unit positioned therebetween to fill the two molds alternately. No provision is made for separate means to stuff the molds.
U.S. Patent No. 3,898,030, issued August 5, 1975 to T.G. sishop~ entitled Injection-Mold Clamping Unit Having Alternately Ejecting Die Assemblies, describes that latches 80A and 80B are used to couple separable mold halves 56A and 58A whereby single clamping and ejection units are used for both molds.
U.S. Patent No. Re 28,721, reissued to J.J.
Farrell on February 24, 1976, entitled Time Saver Plastic Draw-Back Valve Assembly, describes a primary reciprocating-screw -1- ~ :.' ~1 ' i32871~ ~7-423 injection unit 12 and an auxiliary injection piston 50 with a valve 52 for divertinq molten plastic 10w from t~e primary unit to the secondary unit thereby isolatinq the primar~ unit and permittin~ the secondary unit to "stu~" mold 32.
O~her pertinent machine patents include PCT
Publication No. W0 86/011~6, dated February 26, 1986 and We~t German Patent No. ~428780, da~ed Marc~ 13, 1986.
In addition, the prior art shows stack and sandwiah mold arran~ements wherein the molfl cavity plate~ are digposed ~ack to back separated by an inte~ral hot runner. ~epxeeentative of staak mold arran~emen~s are U..S. Patent ~08. 3,7~3,040, 3,973,892 an~ 4,400,341.
Stack or sandwic~ mold arrangementfi are well known in the artl however, their draw backs lnaluae a le~ than optimum operat~nq cycle and lack o~ versati~ity ln component~.
~ dditional publications of interest are U.S. Patent No. ~,752,207, issued June 21, 19~8 to ~aaden, including a related brochure entitled "~TU~RE - Twin~Statlon In~ection-Mouldinq Machlne3" an~ a brochure b~ Stork Plastics Machinery entitled "Stork rJ-Type In~ection M~uldin~ Mach~ne".
, ~ 32 8~1 9 ~7-423 The '207 patent and related Stubbe brochure (publis~ed October 1986) show a ~oose neck connection between a plastic injection uni.t and a distributor carried by a movable platen.
The Stork brochure ~publi~hed on or about 1985) shows an injection unit disposed perpendicular to the mold clamp unit axis.
Moreover, there i9 a disadvantaqe in combini.n~ a hot runner wi.th mold element~ as a sin~le piece part.
Such an arrangement necessita~es replacement o a complete multiple elem~nt mold and ho~ runner as a unit when one wishes to ~han~e molds. Whereas when ~he mold elements are separable from the hot runner ~ystem, i~ ls merely necessary ~o remove mold elements while ~he hot runner remains a machine fixturq.
U.S. Patent ~lo. 4,539,171 ~o ~orensen is al~o of interest. In the '171 patent, ~hermoplastic material i8 transferred from an injection unit to a sandwich mold by means of a so-called snorkel 30 and a cooperatin~ noz~le 16. The snorkel and nozzle make a connection to provide a conduit for thermoplastic material. The snorkel and nozzle move relative to another alon~ a common axis :~
which i~ parallel to an~ spaced ~rom central axi~ 13 alon~ which clampinq platens 10 an~ 11 rec~procata.
.
132~7~
In accordance with one aspect of the invention there is provided in an injection molding machine having a plurality of molding stations arranged in tandem where each station includes at least one mold, each mold comprising a pair of cooperating mold halves, fixed and movable platens supporting the mold halves, a single primary clamping means and a plurality of secondary clamping means for opening and closing the molds in accordance with a plurality of permutations and combinations at the direction of a programmed clamping control means, a process for opening and closing molds comprising the steps of closing all molds by means of the primary clamping means, clamping the mold halves of each mold individually by the secondary clamping means, connecting the primary clamping means to the molds at all stations by means of a serial connection with secondary clamping means, unclamping a f irst pair of mold halves at a f irst mold station, and separating the mold halves at the first station by moving the remaining molds at the remaining stations by means of the primary clamping means and the serial connection.
In accordance with another aspect of the invention there is provided in a method of molding articles sequentially at two different molding stations each having a mold where both stations are within a single unitary injection molding machine, the maahine _4_ , - ,.
-" 172~719 being operable to inject material at a primary injection pressure and at a secondary injection pressure, an improved clamping cycle comprising the steps of arranging the molds of two molding stations A
and B in series, clamping the molds of both stations A
and B to oppose a primary injection pressure, clamping the mold at station B to oppose a secondary injection pressure, injecting molten plastic into the mold at station B solely, releasing the primary injection pressure on the molds of both stations A and B, again clamping the molds of both stations A and s to oppose the primary injection pressure, again clamping the mold at station A to oppose the secondary injection pressure, injecting molten plastic into the mold at station A solely, and again releasing the primary injection pressure on the molds of both stations A and B whereby the molds at stations A and B are clamped under secondary injection pressure independently.
A further feature of the invention is to provide a primary clamping system operable to clamp all mold stations simultaneously. A single primary clamp means cooperating with and making a series connection with a plurality of secondary clamp means is operable in response to a clamp control unit to open and close molds at a plurality of tandemly arranged mold stations in accord with various permutations and combinations.
-" ~328719 It is a further feature of the invention to provide an independent secondary clamping system operable to clamp platens of a given mold station directly and selectively or, in the alternative, operable to clamp mold halves of said given station directly and selectively.
It is a further feature of the invention to mount secondary clamps directly upon the mold platens.
A feature of this invention is a novel molding sequence in which a part molded at a station A, for example, which is serviced by a primary and a secondary injection means may be of entirely different size and structural complexity than another part molded at a station B. In accordance with this feature, filling and stuffing of the mold at station B may be accomplished sequentially by a single injection means.
A still further feature of the invention is that two parts requiring generally equal cooling periods may be molded at two tandemly arranged stations using a single primary clamp means. The single primary clamp means acting upon two stations in the same time interval that would be required if the parts were -molded successively at the two mold stations utilizing primary and secondary clamp means.
1~28719 In contrast to the above prior art disclosures, there is disclosed herein an injection molding machine having a plurality of molding s-tations with a plurality of machine accessories arranged in various combinations developing a sequence of operations calculated to reduce molding cycle time per part particularly when molding large parts, such as large containers or autobody parts.
There is particularly described herein an injection molding machine which enables the mold assemblies to be operable independently of each other and to be readily separable from the machine.
A further feature disclosed herein is the provision of a plurality of mold stations arranged in series and separated by a discrete, central, movable machine platen.
A further feature disclosed herein is the provision of structure for transferring molding compound from an injection unit to a manlfold distributor block along a path which is perpendicular to the clamping axis or the longitudinal machine axis.
A still further feature disclosed herein is the provision of seal means for sealing the injection unit nozzle to the distributor block orifice along an axis I which is perpendicular to the clamping axis.
I
-~32~719 A further feature disclosed herein is the incorpora-tion in the central movable platen of a distributor communicating with whatever mold halves may be attached to the central platen.
' A further feature disclosed herein is the provision of a check valve in the distributor block to prevent leakage of resin when the injection unit nozzle is not in sealing contact with the distributor block orifice.
A further feature disclosed herein is the provision of a central movable platen with individual manifold sections on opposite sides of the platen operable to feed moldable resin to mold halves carried by the central platen under the control of valve means positioned upstream of the central platen. The central movable platen may be cored for cooling and the manifold sections isolated from the platen by an insulating air gap.
A further feature disclosed herein is the ;
provision of valve means in the manifold distributor block operable to place the injection unit and/or a packing unit in communication with the individual manifolds, selectively.
A further feature disclosed herein is the provision of power means for effecting and maintaining the seal between the manifold distributor block and the ~ `
13 2 8 r~
, ~ , injection unit nozzle where the power means operates along a path which is perpendicular to the mold clamping axis.
A further feature disclosed herein is the provision of a plurality of mold stations arranged in series and separated by a discrete, central, movable machine platen.
A still further feature disclosed herein is the feeding of molten plastic into a plurality of individual mold cavities at different, serially arranged mold stations utilizing a single primary injection means and one or more secondary injection means to fill and pack (stuff) each said mold cavity in sequence thereby increasing overall productivity of individual molds.
A further feature disclosed herein is the use of primary injection means dually as a mold cavity ~ ;~
"filler" and a mold cavity "stuffer".
~A further feature disclosed herein is a novel sequencing system for utilizing primary and secondary ~
,,:
injection means to inject molten plastic into a ~-plurality of mold stations clamped by a single, primary clamping means, where the primary injection means performs both, a mold filling and stuffing function at one station 1~ ~
: ' :
. , ~3~871,9 A further feature disclosed herein is the provision of an injection molding machine in which one or more primary injection means are mounted on a fixed or movable platen with track means facilitating motion of the units, to and fro, along the longitudinal axis (x axis) of the machine.
A still further feature disclosed herein is the incorporation, into a multi-station injection molding machine, of a parts removal device or robot which is operable to remove parts molded in reverse or in identical orientation at each station.
A further feature disclosed herein is the provision of a secondary injection means mounted on a movable platen whose design lends itself to a wide -variety of mounting locations on said movable platen, i.e. top, side or bottom of said movable platen.
A further feature disclosed herein is the provision of an injection molding machine on a single rame means comprising at least two injection means and at least four mold stations arranged in series.
-9a- -~7-423 132~7~
An injection molding machine embracing ~eature~
described herein includes, in one comblnation or another, a main frame, fixed and movable platens to support mold halves and primary and secondary clamp means. The secondary clamp mean~ are usually attached to the mold platens, however, i~ nece~sary they may also be mounted directly on mold halves that are attached to the pla~ens.
A distributing manifola iB incorporated in a central movahle platen includin~ valve means or ~irectin~ molten plas~ic to oppose~ mola s~atlon. The manifoLd includes a connec~ion to a primary injection means and to a seconflary in~eat~on means with appropria~e valve means ~or controllin~ flow ~rom the primary injection means.
In an alternative embodiment o~ the machine, the primary in~ection means is pro~rammed to melt su~icient plastic to fill two molds. A irst mold is then filled by the primary injection mean~ and stuffe~ by a secondary in~ection means. Next, molten plastic flow i~ ~;
directed to a second mold station where the filling of the molfl as well as the ~tu~fin~ Btep i8 performed solely by the primary in~ection mean~. In thl~
embodiment the clampin~ ~unction may be 601ely by the ~3~7~9 87-~23 . ..
primary clamp means or by the primary clamp means in combination with ~econdary clamps, depending upon size, configuration and relative coolinq rates o~ the respective molded parts.
Further, the machine includes ejection means and a parts remover (robot) which operates on rec~ilinear coordinates to move from moldinq station to molding station along a ~irst axi3 and into and ou~ of an open mold alon~ a ~econ~ axi 8 .
Product may be molded in the same or in rever~e orientation with appropriate modification of tlle part3 remover and the flow path of the molten plastic.
In rever~e orientation, the remover hea~3 carries flual "plck up" elements, while product molded in same orientation is ~rasped by a remover head wlth a ~in~le pick up.
In certain ~ituatlon~, the ~ize and compLexlty o~
th~ mol~ed parts require the use of a plurality o~
primary injection means adapted to cooperate with a plurality of secondary injection means to insure complete ~illing an~ stuf~ing the corresponding mold cavity in a qiven mold station.
A ~urther embodiment o~ the mac~in0 takes the orm of a double capacity unit. In thi~ arrangement, there ` ~
~328719 87-423 are four molding -qtations, two primary injection means and two central platen~, each incorporating a ~istributor.
o~her features an~ advantages o~ the preisent invention wi.ll become more apparent from an examination of the s~cceeding speci~icatlon when read in conjunction with the appended drawings, in which:
.
~RIF,F DESCRIPTION OF THE DRAWI~C~S
Flg. 1 showici A side view o~ a typical lay out of - t~e sequential molding machine of thie pre~ent invention with the distributor block bro~en away for clarity:
Fig. 2 is a view aimilar to Fig. 1 showing the oppoeite moldin~ station open with the molded part ~ .
poised for removal:
Fig. 3 is an additional side ~iew ~howing both mold stations in the closed condition with primary anfl :~
secondary clamp mean~i In operation:
- Fiq. 4 is a side of the machine with the moldefl .
part~i remover or robot in an open mold retrieving a part;
Fig. 5 is a top plan view of the illustration of Fi~
Fig. 6 is similar to Fi~. 5 showing the robot in the opposite moldinq stationJ
13287~9 87-~23 , , Fig. 7 i~ a plot of the machine sequence o~
operation charti.ng the position of the various mac~ine accessories against the step by step generation o~ the molded parts Pig~. 8, 9 and 10 show an alternative arrangement of primary and secondary injection means ~erving two molding stations;
Fi~. ].1 is a plan view of an injection molfling machine with an alternative ~econdary or parting line clamp ~tructure, Fi~. 12 is a schematic illustration of details of the structure and moun~inq mean~ o t~e alternative . seconaary clamp o~ Flg. 11;
¦ Fi~. 13 is a plan view of a ma~hine modification in w~ich a plurality of primary injection means are :
utilized in combination with a plurali~y o~ di~tributor block~ anA corre~ponding aecondary in~ection mean~
Fig. 14 is a side view of an additional machine modi~ication showing double sets o~ primary and secondary injection means and robots ~ervicing ~our mold stationss Fi~. 15 is a char~ fletailing the opera~ing sequence o~ the machine o~ Fiq. 14;
. -13~
~: ' .
~7-423 ~328'~19 Fi~. 16 i.s a side view o an altexnative machine arrangement facilitating molding piece parts in the same physical orientation using a single primary in~ection means Fi~. 17 is similar to Fiq. 16 modified to use two primary injection units;
Fi~. 18 is a cycle chart for the Fi~ 18 modi~icationt Fig. 19 is a plan view o a modi~led molding machine with por~ions broken away to illustrate an al~ernative manifold structure, Fiq. 20 is a plan view of a portion of Fiq. 19, enlarged, showinq the hot runner sy~tem, the in~ection .
unit ~extruder), the injection unit nozzle clamp means and mold halvesS
Fig. 21 iB a view similar to Fig. 20 showinq the in~ection untt in po~ition to ~upply mol~able material ~. :
to the hot runner 6ystem with the injection unit nozzle clamped to the hot runner ~ystem, Flg. 2~ is an elevational view of the ri~ht side of Fiq. ~1 showing the valve means for switclling molding material to manifold sections, the nozzle clamping means and a packing cylin~er or ~tuffer, and, Fi~. 23 ls a ~ectlonal view, enlarqed, a~ viewed in the plane of the line 5-5 o Fiq. 20 and in the ~7 - a~2 3 ~328~19 direction o~ the arrows, s~owing the seal between the nozzle and the manifold distributor block and showing the valve means.
DE~AILED DESCRIPTION OF THE PREFER~D EMBODI~EN~
Referring ~o Figs. 1, 2 and 3, a basic embodiment of the injection moldinq machine o~ the present invention is disclosed comprising molding stations A and B havin~ es~ential aacessories deining a primary clamp section 11, a ~econflary clamp sectiort 12, a primary molten plastic injection section 13 anfl a secondary injection section 14. Either ~he primary and/or 3econdary injection unit may be o~ the reciprocating screw type or pi_ton type.
Molds 16 and 17, frequen~ly of diferent configura~ions, comprise mol~ halves 18 and 19 and 21 and 22, respectively.
Mold halves 19 and 21 are mounted on central movable platen 26 and halves 18 and 22 are mounted on movable platen 24 ana ~ixed platen 27, respectively.
Platens 23 and 27, fixed to the machine frame 31, upport tie bars 28 and 29 in the usual and cu~tomary ashi on .
' - --].5--i ~7-~23 132~719 Pla~en 24 i9 connected to primaxy clamping pi~ton 32 and is reciprocated thereby sliding on tie b~rs 28 and 29.
~, Central platen 26 is also movable on tie bars 28 ana 29 and i~ releasably connected to movable platen 24 and fixe~ platen 27 by ~econdary clamping mean0 12 in a manner which will be explained in qreater ~etail as this :' ... .
specification proceeds.
Machine section 14 includes a di~tribution block 33 incorporated in platen 26, wi~h heating ~lemente 34, ~. molten plastic supply channel 36 and sel~ctor valve 37 ¦ ~~or diverting compound ~low from station A to ~tation B
and vice ver~a.
~ he Ai~tributor blocX 33 terminates in a cylinder ~8 ~aving a pis~on 39 an~ a reservoir 41.
A ~econ~ c~annel 42, adapted to make a connection with a reaiprocatin~ primary in jection ~ection 13, a~ i8 most apparent in Fi~. 2, include6 a shut off valve 42 for cu~ting off molten plas~ic ~low from the primary injection means.
With the plston 39 in the retracted po~ition, a~
shown in Fig. 1, the molten pla3tic advanced by the ~i injection section 13 opera~e3 to ~ill the mold cavity to which 0elector valv- 37 is ~et ~tation B in ~ and ~imultaneously ills reservoir or accumulator 41. ~1pon ~:
~ ' ' ~ -16-87-~23 ~32871~
closure o~ ~hut of valve 43, i~olating the injection section 13, actuati,on of the piston 39 i9 operable to "stuf~" t~e mold cavity to which molten plastic was inltially directed.
~ bviously the reservoir can be reestablished and rechar~ed upon retraction of the piston 39 in preparation to char~e the opposite mold cavity.
Typically, the injection section 13 include~ a plasticizing-i.n~ection unit re~erred to in the ar~ a~ a reciprocating-screw extruder.
Fi~s. 4, 5 and 6 are similar to Flg~. 1, 2 and 3 and ~how de~aila o~ one em~odiment o~ the ~econdary clamp means and the structure and operation o~ the ~
molded parts removal unit or robot. , Referrinq to Fig. 4, the parts removal-unit operate~ automa~iaally in tlmed ~quencei in rohot ~ -~ashion, and includes a first Leq 44 which reciprocates ~;
under control of power unit 46 alon~ the lon~itudinal axis (x axis) o~ the machine guided by a track (not ~ ' shown). ~he power unit 46 i8 supported by ~ixe~ platen 27. `
When the part removal head 48 is in register with an open mold, such as t~e open mold at station A ~n Fiq.
4, a second ley 4~ i9 actuated by suitable power mean~
to advance the head alon~ a eeaond axis (~ axis) into ' ~
~7-~23 ~28719 re~ister with finished part P. The part is then ejeated from core 51 by ejector pins 52, in well known fa~hion, and picked up by the head.
The head 48 is provided with a source of vacuum and a valve operable to direc~ vacuum to the part side of the head where upon the part P is grasped and drawn away from the core by the head. The heafl i6 retracted automatically and the part P released to an appropriate container (not shown) for packa~ing or further processing, as the ca~e may be.
Fig~. 5 and 6 are top plan views o~ the illu~tration of Fig. 4 anfl show details and operation o~
one embodiment of the secondary clamp sea~ion indlcated generally by the re~erence numeral 12.
Pairs o~ opposed arms S3 and 54, ixed to central platen 26, are formed with notche~ 56 and 57 and cam ~ace~ 5~ and 59. The notche~ are enga~sfl by ~og~ or lu~s 61 and 62 having mating cam faces 63 and 64. The lu~s 61 anfl 62, operable to reciprocate in timefl sequence un~er the control of pl~ton-cylinder ~ssemblies 66 and 67, are mounted on the movable platen 24 and fixed platen 27, xespectively.
As mold halves of a given mold station approach their closed po~ition, the lu~s move into matlng notche~
..
. . .
~7-~23 ~328719 and the mating cam faces engage one another to drive the mold halves into ti~ht face to face contact holdin~ the ~old halves sealea during cavity stuffing and subsequent cooling period independently of the primary clamp means in a manner and according to an operating ~equence set forth in the cycle chart of Fi~. 7.
Fiq. 6 shows the part removal head 48 in place in the open mold at ~tation s poisefl to retract ~rom the mold to transfer part P out of ~he machine.
In thi~ po~ition t~e vac~um o~ the head 48 ha~ ~een diverted fro~ the ri~ht side of the head to the left side of the head as viewed in Fiq. 6 to accompli~h the part pick up at station s.
Referrin~ in de~ail to Fig. 7, a plot showing a typical molding cycle of the machine of Figs. 1 ~hrough 6 is lai~ out coordinately where t~e y axis i8 a ~che~ule of sequenti~l positions o~ the variou~ m~chin~
components or accessories for stations A and B, and the x axis i8 a schedule of the proqres~ of the part through the molding ~teps.
The chart is read in the following fashion:
startin~ at the upper left hand corner at the polnt in~icatea by the letter S, one 'IpiC~8 Up'l the moldinq cycle by notin~ the small c~rcle~ extendin~ alon~ t~e y axis w~ich indica~e that primary clamp 11 is open, -19~
1 .
87-~23 13287~9 injection section 13 is back (to the right in Fig. 4), the injection section 13 i.6 plasticizing, shut o valve ~3 is closed, secondary injecti.on section 1~ (stu~fer piston 38) is retracte~, selector valve 37 i~ open to station ~, secondary clamp section 12 is clamplng R tation A, secondary clamp 12 at station B is free (open), ejector pins 52 are retracted at station A, ejector pins 52 are forward tejecting) at station B, robot or pick up hea~ 48 ha~ moved alon~ machine x axi~
to station B and along t~e z axis into the mold at ~tation ~.
~ eferring to the point x at the lower lef~ corner o~ the chart of ~iq. 7, i~ i~ apparent when the variou~
mac~ine elements are in the po~ition~ ~uat indicated by "reading" the char~ a molfled part is coolin~ in it~ mold at ~tation A and ~he robo~ or pick up head 48 i~
positioned in ~e open moLd at station B.
The chart is read in the manner de~cribed incrementally from le~t to right, the machine having produced two part~ P upon arriving at end E of a complete cycle.
Referring now to Fi~s. 8, 9 and 10, an alternative embodiment of the primary and seconaary injection means i~ ~isclosed schematically. In thi~ arrangement molding stations A and B are serviced by an in~sction unit 68 ~328719 87-~23 and secondary injection unit 69. A selector valve 71, (qhown as a two way valve but which ma~ be a three way valve) disposed in ~istributor block 72 within platen 70, i8 operable to ~ivert the flow of molten plastic from injection unit 68 to the mold at station B as indicated schematically in Fi~. 9 or to the mol~ at~;
s~ation A as indicat~d sc~ematically in Fi~. 10. Thus, ~ .
operation of the injec-tion unit in the Fi~. 9 :~
arrang~ment delivers molten plastic simultaneously to the mold o~ station B an~ to the seaon~ary in~ection unit 69. At ~he appropriate interval ~elector valve 71 : :
directs the mol~en plastic to mol~ station A wllile in~ection continues into station B rom the 6econdary in~ection unit, The signlflcance o~ this arr~n~ement i~
that (1) the primary in~ection unit is pro~rammed to prepare sufficient plastic to satisfy the molas of both .
mold stations A and Bt (2) the s~condary in~ection unit 69 completes injection into the mold at ~tation B a~ter ~ ~
selector valve 71 shifts the flow of plastic to station ~ :
A; ~3) molten plastic i5 delivered directly to ~tation A
~rom the primary injection unit to comPlete the :~
in~ection, whereby either the primary and/or secondary unit may serve as a stuffer. For example, as a variation of this embodiment one may also stu~f station A with ~econdary in~ection unit 69 wi~h appropriate valving,.
. -21-~; - . -. ~ :
13287~9 Either the primary or ~econdary in~ection uni~s may be of the reciprocating screw type or the piston type~
Injection pressure of molten plastic into a mold cavity to fill a mold cavity is fre~uently of a level ranging from 15,000 to 21,000 psi and injection pressure to "hold or stuf" the cavity to com~ensate or shrinkage is frequently of the order of 6,000 psi.
~ he~e pre~ure levels can be develope~ by prlmaxy and/or secondary in~ection means.
When piece part~ molfled at ~tations A and B have substantia]ly uniform or equal cooling period~, secondary clamping mean~ (parting line clamps) can be eliminated and the molds of sta~ion A and B are held clamped by the primary clamping unit and both molds are opened simultaneou~ly.
In situation~ where the cooling periods are unequal it is ne~e~sary to u~e part~ng line clamps in ad~ition to primary clamp.
Referring now to Fig~. ll and I2, an alternatlve design for a secondary clampin~ unit i~ di~losed wherein partin~ line clamp elements 73 and 74 are shown mounted on mold halves 75 as at 76 shown in Fi~s. 11 and 12. The units at station A and s~ati.on ~ are of iden~ical structure. There~ore, only one modi~ie~
seoondary clamping unit will he described~
.. ,: :: - . -~ ~7-~23 ~287~9 The clamp elements 73 and 74 are opera~ed by a pi~ton-cylinder arran~ement 77 on opposite side6 of a mold station such as is shown at s~ations A and B in Fig. 11. Matinq mold halves are ~ormed with eut out~ or :
recesses 81 and 82 fitted with hardened inserts 83 and 84 secured to mold halves by bol ts 87 and 88. Each insert is formed with a taper matin~ with a ~-corresponding taper on the complementary elamps 73-74.
Actuation of the e~linder unit 77 moves the clamps on opposite sides o~ the moLd~ along a piston rod 86 (fixed to a mold half as at 76) ~rom a retraete~ posi~ion of Fig. 12 to an operatinq position shown ln Fi~. 11 driving the ~old halves into fAee to faee contaet under very high compressive stress.
~ote that the parting line elamp ~truatur~ of Figs. ;~
11 and 12 i6 moun~ed directly on the mold halves and operates directly on the mol~ halves, in contrast to the seeondary clamp strueture described previously whicll i9 mounted on the mold platens and operates direetly on the mold platens.
Obviously, any of a number of arrangements may be devised in mounting the seeondary clampin~ arrangement on the mold halves as engineering and other design eonsiderations dletate.
.
, ~ .,.
' 87-~23 ` 132~719 I Referring to Fig. 13, a ~urther alternative '~ embodiment of the injection molding machine is disclosea wherein the open mold configuration at station B
represents a large, complex part. In order to insure adequate flllin~ and stu~fin~, a machine modification is arranged wherein a plurality of primary injection units ~1, 92 and 93 are mounted on the top of fixed platen 94. Suitable tracks 96 are provided for advancin~ tl~e injection unit~ to and ~ro to make appropriate connection with matin~ ~econdary in jection units ox ~tuf~ers 97, 98 and 99 incorpora~ed in a central movable ~ platen 101. Thus, in operation ~he primary injection .' unit~ and cooperating ~tu~er units are operable individually or collectively in various combinat~ons and permutation~ a~ de~ign complexi~y o~ the molded part~
aictat~ .
Obviou~ly, the po~ition and number of the primary injection and cooperating stuffer unit~ is a matter of choice con~istent with part retrieval, overall length o~
machine, ~loor space and so ~orth.
Fig. 14 illustrates a double capacity ~achine in which there are four molding stations A, B, ~ and D, two oppo~ed primary in~ection extruder3 10~ and 103 with ~wo central mold platens 104 and 106 each incorporatin~ a secondary extru~ion unit~ or stuX~ers 107 and 108, in .~
87-~23 ~L32871~ ~
the fashion and for the purpo~e previously described, for servicing mold stations ~ and C on the left and mold stations B and A on the right, respecti~e]y. ~he reference numerals ]09 and 111 designate mold part removal units or robot~. Naturally, each mold station could have a plurality of molds as required.
Hereagain, the location of primary injecting units i8 a ma~tex of ~e~ign choice based on machine ~ize lim~'tations and available operating ~pace.
~ he machine con~i~uration o~ Fi~. 14 show~ the mold~ open at stations A and D while the molds at station~ R and C are closed.
This confiquration is developed in the following ~ a gh i on .
I Assume tha~ the primary clamping means actuated by ~-piston 32 has moved all movable platens 24, 104, 25 and lOfi to the r~ht a~ainst stationary platen 27 clo~lng all molds at stat1ons A, a, C an~ D with all secondary clamps 12-12 latched.
11pon an appropriate signal from the clamp control ~Figure 5), the secondary clamp 12 at ~tation A i~
relea~e~ while the secondary clamp~ 12 a~ s~ation~ B, C
and D remain latched.
~2~719 The piston 32 i~ ordered to move to the left. This occurrence opens ~he mold at ~tation A and dog 117 secured to movable platen 25 moves ~rom the da~hed line position to the solid line position to abut stop 118.
Contact between the dog 117 and stop 11~ stop~
movable platen 106 in the position shown in Fig. 14 and blocks further separation of mold halves at station A.
Upon the occurrence o~ t~e above-noted abutment and in timefl se~uence, the secondary clamp at station D i8 . . :
unlatched 80 that upon continued motion of the piAton 32 to the left the mold at station D opens to complete development of the mold layout shown in Fiq. 14, i.e.
molds at Rtation~ A and ~ are open and mol~s at station~
B and C remain clo~e~ and clamped.
Aqain starting from a closed mold position at , stations A, B, C and D, ~he molds at station~ ~ an~ C
are openefl in similar fashion in response to the appropriate si~nals ~rom the clamp control unit.
Fig. 15 is an operating schedule showing the sequential positions o~ the various machine accessories as the double capacity unit o~ Fi~. 14 operates to produce ~our molded parts per cycle.
Fig. 16 shows a machine arrangement in which a single primary injection unit i5 utilized to mold parts at ~tations A and B where each part i8 molded in th~
13287~
same physical and ~patial orientation. Si~niicantly, in this arrangement, the robot head require~ only a single pick up unit in that each mold part iB graaped while dlsposed in t~e same orientation.
In this machine configuration a segment of the molten pla~tic flow channel leading to ~ta~ion B i~
carried by and reciprocates with the central platen 104 and is separa~le ~rom ~he flow channel serv~ng station A
as ~hown by the re~erence numeral 100. The ~low channels opera~e to ~upply the mold at ~tation B when valve~ 112 and 113 are open and ~alve 114 ia alosed.
Ater injection and suitable holdin~ at station B valves . and 113 are clos~d, valve 114 is opened and molten plastic i~ injected into the mold a~ sta~ion A at the ¦ appropriate time in ~he molding cycle. In order to I ~acilitate ~his arrangement, a conical cut out 116 1 j ~ormed in the stationary platen 119.
¦ Dependinq, ~or example, upon the s~milarity of molded parts anfl cooling time required, use of a ~econdary injection unit or stuffer i~ optional.
Correspondin~ly, u~e oE secondary clamp units iB al80 an optional acces~ory. The necess~ty ~or secondary clampin~ unit~ depends primarily on ths relative cooling rate~ o~ the part~ m~lde~ at each ~ation.
1` .
:,; , .
~328719 a7-~23 Fig. 17 shows a modification of the arran~ement o Fig. 16 in which two primary injection units are utilized, one ~ervicin~ molding station A and the another servicing station B. In this arrangement, stuffer unit~ are unnecessary in that the primary injection units act dually to perform the mold filling and mold ~tufing function.
Fig. 18 i~ a chart of the molding cycle of Fi~. 17 indicating the various posi~ions of maahine accessories fluring the course of moldin~, coolin~ and e~ecting piece parts ~rom stations A and B ~equentially.
When using more than one injec~ion means, ~iferent resins may be injec~ed into ~ eren~ mold aavities or di~erent resins may be coinjected in the ~ame mold cavity to gain a layered waLl ~ruature.
DE S CR I PT I O N OF T HE ALTE R NAT I VE EM BOD I M ENT
Referring now to Figs. 19-23, a modified in~ection moldin~ mac~ine indicated ~enerally by the reference numeral 111 includes fixed platens 112 and 113, carried by a base frame supporting pairs of tie rods 116-116 and 117-117 in the usual and customary ~ashion. A movable oentral pla~en, in~icated generaLly at P, incorporating a hot runner ~y~tem compri3es a manlfold distributor ..
~a28719 block 120, moldable material switching valve means 121, manifold mean~ de~ining manifold section5 122 and 123, and mold halves 124 and 126 supported by said central platen Central platen P is movable in coo~eration wit~
movakle platen 127 to open and close mold hal~es at mold stations indicated at A and B to mold articles, such as At C.
The clamps 128, 129, 131 and 132 operate ~o ~eal and maintain close con~act between mold halves durinq molding in controllefl ~eq~ence.
Note that manifold section~ 122 and 123 s~raddle and are supported removably by movable central platen 136.
Except ~or suitable fastenlng means and ~pacer~
~not shown), the manifold sectlon~ 122 and 123 are isolated from the central platen 136 by an insulatinq air gap indicated by the reference numeral lOS.
Frequent~y, it is desirabla to includè cooling coils in the central platen 136 to prevent ove~eatin~ ;;
and attendant expansion o~ the platen leading to siezing t~ the tie rods 116-116 and 117-117.
Cooling of the central platen 136 in combina~ion with the insulating air gap 105 protects the manifold sections 122 and 123 from overheating.
r~'" ~
87-~23 ~32g71~
Mold ha].ves 124 and 126 are also supported by ~he central platen 136 and the manifold section~ 122 and 123 are sealed against respective-mold halves 124 and 126 about the periphery o~ mold openings 106 by seaL means defining a raised annulus or boss as indica~ed by the reference numerals 100 and 101.
Mani~olfl dis~ributor block 120, connected ~o the central plat~n 36, include~ molding material ~witc~ing valve 121 and provide~ ~upport for an injection unit nozzle clampin~ mean~ in~icated generally by the ~e~erence numeral 142.
An injection unit in the o~m of an extruder 143, movably ~upporte~ b~ means (not shown), i8 movable from the po~ition shown in Fig. 20 to an in~ection position indicated in Fi~. 21, alon~ a Fath or axi~ indicated by the reference nume~al 144. The axis 144 is generally parallel to the injection mol~ing machine axis (mol~
clamping axis~ indicated by the reference numeral 146.
When the injection unit 143 is in the in~ection position (Fi~. 21), nozzle 147 i~ aligned with and commUnicates wit~ ori~ice 1~8 o~ manifold di~tributor bloclc 120.
A seal, indicated at S~ ig. 23~, is-e~fected by the contact hetween 6urface 149 o~ mani~old di3~rlbutor bloclc in~ert 151 and sur~ace 152 of noz le insert 153.
.
.,.,: - ~ . : i i. . : ~ . ., ` : : : : . . . .
87-~23 ~ he seal i~ maintained by no~zle clamping means 142 defining, in this embodiment of the invention, cylinder 154 with cooperating piston 156 secured to,the manifold ~istributor block 120 by rods 157. The nozzle clamping means acts alon~ axis 160, whlch is perpendicular to machine or clamping axis 14~.
Switching valve means 121, upstream of the manifol~
mean3, defining a spool valve i8 operatefl in cyclic fashion in ~ynchronism with ~he molding cycLe ~o switch moldable material to appropriate maniold sea~ion 122 and 123 via condults 133 and 13~ (Fi~. 23). The 8pool valve 121 is rec~proaated by valve opera~ng ayllnder ~ -159 (Fi~. 22), a~ indicated by the arrow 161 oP Fiq. 23.
Ball clleck valve 162 i~ provided in moldable material flow path 163 to prevent leakage when the nozzle i~ unalamped and the seal between the no~le and ~:
the manifold di~tributor block i~ broken.
A stu~fer or packer unit 164 is located upstream o the spool valve 121 and communicates with the flow path 163 via conduit 16fi. ~:
I~ is anticipated ~hat the ~troke of the in~ection ;
unit 143 in moving ~rom the position o~ Fiq. 20 to the injectlon position of Fi.g. ?.1 will vary from one molding set-up to another dependinq upon the "buil~ up" or ~ thickne~s of the mold halve~. ~
:: ' 1;'''' .. , ,,.,.,, "` . .' .. ''~ ; ' . ' ' ' ~32871~
That is, the injec~ion poi3ition will vary along the machine axis depending upon ~he dimensions o the mold halves in the closed position measured alon~ the lon~itudinal or clamping axiis o~ the machine.
The stroke o~ the injection unit is also advanta~eous in that it provides access for a robot or other automatia molded article retrieval device to enter open mold halve~i to ~rasp and remove a mold~A ~r~icle C.
It iq ~o be understood that the invention i~ not limited to the illustrations described and shown hereln, whiah are deemed to be merely illustrative of the best modes of carrying out the invention, and which are susceptible of modificat~on of form, i~ize, arrangement o parts anA detall~ o~ ope*atlon. The invention rather is lntende~ to encompass all such modi~ication~ w~lch are wlthin it~ spirit and scope as defined by ~he claims.
Claims (3)
1. In an injection molding machine having a plurality of molding stations arranged in tandem where each station includes at least one mold, each mold comprising a pair of cooperating mold halves, fixed and movable platens supporting said mold halves, a single primary clamping means and a plurality of secondary clamping means for opening and closing said molds in accordance with a plurality of permutations and combinations at the direction of a programmed clamping control means, a process for opening and closing molds comprising the steps of:
closing all molds by means of said primary clamping means, clamping the mold halves of each mold individually by said secondary clamping means, connecting said primary clamping means to the molds at all stations by means of a serial connection with secondary clamping means, unclamping a first pair of mold halves at a first mold station, and separating the mold halves at said first station by moving the remaining molds at the remaining stations by means of said primary clamping means and the serial connection.
closing all molds by means of said primary clamping means, clamping the mold halves of each mold individually by said secondary clamping means, connecting said primary clamping means to the molds at all stations by means of a serial connection with secondary clamping means, unclamping a first pair of mold halves at a first mold station, and separating the mold halves at said first station by moving the remaining molds at the remaining stations by means of said primary clamping means and the serial connection.
2. The method of claim 1 including the steps of blocking further separation of said first pair of mold halves to limit separation, thereafter unclamping a second pair of mold halves at a second station whereby said second pair of mold halves separate as a result of continued molten of said primary clamping means.
3. In a method of molding articles sequentially at two different molding stations each having a mold where both stations are within a single unitary injection molding machine, said machine being operable to inject material at a primary injection pressure and at a secondary injection pressure, an improved clamping cycle comprising the steps of:
arranging the molds of two molding stations A and B in series, clamping the molds of both stations A and B to oppose a primary injection pressure, clamping the mold at station B to oppose a secondary injection pressure, injecting molten plastic into the mold at station B solely, releasing the primary injection pressure on the molds of both stations A and B, again clamping the molds of both stations A and B
to oppose said primary injection pressure, again clamping the mold at station A to oppose said secondary injection pressure, injecting molten plastic into the mold at station A solely, and again releasing the primary injection pressure on the molds of both stations A and B whereby the molds at stations A and B are clamped under secondary injection pressure independently.
arranging the molds of two molding stations A and B in series, clamping the molds of both stations A and B to oppose a primary injection pressure, clamping the mold at station B to oppose a secondary injection pressure, injecting molten plastic into the mold at station B solely, releasing the primary injection pressure on the molds of both stations A and B, again clamping the molds of both stations A and B
to oppose said primary injection pressure, again clamping the mold at station A to oppose said secondary injection pressure, injecting molten plastic into the mold at station A solely, and again releasing the primary injection pressure on the molds of both stations A and B whereby the molds at stations A and B are clamped under secondary injection pressure independently.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000616478A CA1328719C (en) | 1988-01-29 | 1992-08-31 | Sequential injection molding machine |
Applications Claiming Priority (6)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US07150157 US4867938B1 (en) | 1988-01-29 | 1988-01-29 | Sequential injection molding process |
| US150,157 | 1988-01-29 | ||
| US294,308 | 1989-01-06 | ||
| US07/294,308 US4981638A (en) | 1988-01-29 | 1989-01-06 | Method and apparatus for clamping an injection unit to a molding machine |
| CA000589420A CA1315507C (en) | 1988-01-29 | 1989-01-27 | Sequential injection molding machine |
| CA000616478A CA1328719C (en) | 1988-01-29 | 1992-08-31 | Sequential injection molding machine |
Related Parent Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000589420A Division CA1315507C (en) | 1988-01-29 | 1989-01-27 | Sequential injection molding machine |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1328719C true CA1328719C (en) | 1994-04-26 |
Family
ID=27168198
Family Applications (3)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000616479A Expired - Fee Related CA1328720C (en) | 1988-01-29 | 1992-08-31 | Sequential injection molding machine |
| CA000616478A Expired - Fee Related CA1328719C (en) | 1988-01-29 | 1992-08-31 | Sequential injection molding machine |
| CA000616480A Expired - Fee Related CA1328721C (en) | 1988-01-29 | 1992-08-31 | Sequential injection molding machine |
Family Applications Before (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000616479A Expired - Fee Related CA1328720C (en) | 1988-01-29 | 1992-08-31 | Sequential injection molding machine |
Family Applications After (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000616480A Expired - Fee Related CA1328721C (en) | 1988-01-29 | 1992-08-31 | Sequential injection molding machine |
Country Status (1)
| Country | Link |
|---|---|
| CA (3) | CA1328720C (en) |
-
1992
- 1992-08-31 CA CA000616479A patent/CA1328720C/en not_active Expired - Fee Related
- 1992-08-31 CA CA000616478A patent/CA1328719C/en not_active Expired - Fee Related
- 1992-08-31 CA CA000616480A patent/CA1328721C/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| CA1328721C (en) | 1994-04-26 |
| CA1328720C (en) | 1994-04-26 |
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