CA2192503A1 - Blow molding machine operating in accordance with the reheat method for producing hollow plastic articles - Google Patents
Blow molding machine operating in accordance with the reheat method for producing hollow plastic articlesInfo
- Publication number
- CA2192503A1 CA2192503A1 CA002192503A CA2192503A CA2192503A1 CA 2192503 A1 CA2192503 A1 CA 2192503A1 CA 002192503 A CA002192503 A CA 002192503A CA 2192503 A CA2192503 A CA 2192503A CA 2192503 A1 CA2192503 A1 CA 2192503A1
- Authority
- CA
- Canada
- Prior art keywords
- blow
- path
- parisons
- heating
- deflection
- 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.)
- Abandoned
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C49/00—Blow-moulding, i.e. blowing a preform or parison to a desired shape within a mould; Apparatus therefor
- B29C49/42—Component parts, details or accessories; Auxiliary operations
- B29C49/4205—Handling means, e.g. transfer, loading or discharging means
- B29C49/42113—Means for manipulating the objects' position or orientation
- B29C49/42121—Changing the center-center distance
- B29C49/42122—Adapting to blow-mould cavity center-center distance
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C35/00—Heating, cooling or curing, e.g. crosslinking or vulcanising; Apparatus therefor
- B29C35/02—Heating or curing, e.g. crosslinking or vulcanizing during moulding, e.g. in a mould
- B29C35/08—Heating or curing, e.g. crosslinking or vulcanizing during moulding, e.g. in a mould by wave energy or particle radiation
- B29C35/0805—Heating or curing, e.g. crosslinking or vulcanizing during moulding, e.g. in a mould by wave energy or particle radiation using electromagnetic radiation
- B29C2035/0822—Heating or curing, e.g. crosslinking or vulcanizing during moulding, e.g. in a mould by wave energy or particle radiation using electromagnetic radiation using IR radiation
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C2949/00—Indexing scheme relating to blow-moulding
- B29C2949/07—Preforms or parisons characterised by their configuration
- B29C2949/0715—Preforms or parisons characterised by their configuration the preform having one end closed
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C49/00—Blow-moulding, i.e. blowing a preform or parison to a desired shape within a mould; Apparatus therefor
- B29C49/02—Combined blow-moulding and manufacture of the preform or the parison
- B29C49/06—Injection blow-moulding
Landscapes
- Engineering & Computer Science (AREA)
- Manufacturing & Machinery (AREA)
- Mechanical Engineering (AREA)
- Blow-Moulding Or Thermoforming Of Plastics Or The Like (AREA)
Abstract
To be able to guide the parisons in a reheat type blow molding machine having separate heat and blow paths along the path where they are heated up to blow temperature, i.e., in narrowly spaced relationship past the heating devices, with the spacing being independent of the pitch of the mold cavities on the blow path, and to be able to blow a plurality of parisons on the blow path at the same time, the present invention suggests a straight heating path (1) and at least one straight blow path (7), and that the transportation device (2) for receiving parisons in close pitch should comprise arms (4) which laterally project in such a manner that the deflection radius (r) of the transportation device (2) of the heating path (1) is smaller than the deflection radius (R) of the mandrel type receiving means, and that at least one transfer device (11) should be interposed between a deflection portion of the heating path (1) and the portion of the blow path (7) which faces the deflection portion, and should be controlled in such a manner that it grips the parisons and puts them on the blow path when the parisons on the deflection portion of the heating path (1) are spaced apart from one another at a distance corresponding to the spacing of the blow mold cavities on the blow path (7).
Description
' 21925Q3 A blow molding m~chine operating in accordance with the reheat method for producing hollow plastlc article~
_______________________________________________________ The present invention relate~ to the production o~ plastic hollow articles in a spec~al type of blow molding process wherein pa~ison6 made in an in~ection molding proce~s are taken from a supply device and heated on a hoating path to blow tQmperature and are subsequently transferred into one or a plurality of blow molds in whlch they are blown to form hollow pla~tic articles of a 6hape and size predetermined by the mold cavity of the blow mold, subsequently cooled and then removed. Such a method in which cold parison~ that have b~en removed from a supply device are aga1n heated up to blow t~mperature is mo6t of the time called "reheat m~thod".
To be able to heat the individual par~60ns evenly up to blo~
temperature over their entire length and above all o~er their entire cross-section, and since the heat penetrates through the cross-section only at a relatively slow pace, the pari~ons mostly move on 8 long heating route along a straight or circular p~th on which spaced apart heating units, mostly i~rared radiators, are arranged, the portions of the path between the heating units being so-called compensating or cooling sections in which the heat, which has externally been ~pplied to the parisons, has enough time to penetrate through the cross-section. Moreover, these sections are to ensure that the external wall of the parison i6 not overheated, - 21925~3 -which happens quite often wlth many plastics that are sens~tlve with respect to the 60-called proce~s window.
Such a ~ystffm does normally not present any difficulties in cases where only one parison i~ transferred ~nto a blow ~old one at a time after having passed throug~ the heating path (e.g. EP 0 387 735 Al). By contrast, if pari~onc are to be transferred into a plu~ality of blow molds arranged on a spec~al blow path 60 as to incr~ase the output snd thu~
enhance the economlc e~ficiency of a reheat ~ystem, the di~ficulty ari~es that th~ pari~ons are ~o move along the heating p~th in A relat1vely close pitch for an e~ficient exploitation of the radiation emitted, while the pitch of th~
cavities of the blow molds has to ~e adapt~d to the volume of the blown ~ollow articles and thu6 to the size o~ the blow moldc with their cavitie6 or ~old cavities and cooling chaDnels, i.e. the parison~ are to pass along ~hs heating path in ~elatively close pitch, whereas the blow mold ca~ities mu~t be acco~mo~Ated on the blow path in wider p tch in comparison therewith.
DE 31 30 129 A1 de~cribe~ this problem and suggests, as the solution, a heating wheel which rotate~ between heating boxes ~ixedly arrsnged on the outer circumference with a clo~e pitch ~or the parison6 or the retAinin~ mandrels receiving said parisons, from which wheel they are trans~erred by a tran6fer wheel to a blow wheel on which the blow molds ere arranged in a pitch adapted to the size of said molds. As for the 6uggestion made in DE 31 30 129 Al, a transfer is possible for the rea~on that at the beginning not each of the retaining mandrels is equipped with a parison fxom the supply device, but only e.g. the first, third, fifth, 6eventh mandrel dnd then after ~ complete rotation of the h~ating wheel every second, ~orth, sixth, eighth ... retaining mandrel, and a paricon i~ transferred accordingly into a blow -mold only after two rotations. since a new parison is simultsneou61y put onto every po6ition on the heating wheel that has b~come free due to transfer to the blow whesl, with the parison being tran~ferred into a blow mold on the blow wheel ~fter t~o rotations, the m~chine operates continuously, and since it i6 only every second pari~on that is transf~rd from the ~oating wheel to the blow wheel ~n continuou~
sequenre, the pitch on the blow wheel can be twice a~ great ~s ~hat on the heating wheel. o~ cour~e, in this method every pa~ison can e.g. pa58 through the heating path three tLmes be~ore being transferred to the blow wheel, and the blow mold pitch can be chosen accordingly.
Th16 mothod, however, has, e.g., the disadvantage that in thi~ sy6tem, too, only one blow mold including a cavity can be filled with a pari~on one at a time and al~o that every parison hss to pass through two rotation6 of the heating wheel before being removed from the he~ting wheel and transferred to the blow wheel, with the effect that the heating p~th consi6ts of two equal sections, 60 that, as ~ar as a heating operation up to the blow temperature is conc~rned, there i6 no pos6ibility of adaptively ~hanqing ~he heating conditions and the compensating and/or cooling section~ between the heeting devices during the ~econd run in compari~on with the first ~un.
Moreove~, a machine which operates in accordance with this known system requires noticeably more space ~or the same output.
It has therefore been the object o~ the p~esent invention to prrovide a reheat type blow molding machine with the aid of which it i6 not only po~ible to guide the parisons in close pitch on the heating path past the heating section~ and the inte~po6ed compen6ating and/or cooling sections, while the '~192sn3 blow mold or blo~ mold cavity pitch on the blow path i6 independent of the pitch of the pari6cns on the heating path, but with which ~ plurallty of blow mold~ ~n th~ blow path or one or a plurality of blow mold6 with a plurality of blow cavitie~ can simultaneously be equipped with parison~ which c~n simultan~ou61y be blown to form hollow pla~tic article~.
This ob~ect of the lnvention is sol~ed ~ith the means de~ined in p~tent clatm 1. The subclaims relate to expedlent embodiments o~ the inventive idea. The invention 18 illus~rated in the drawings wi~h re~erence to ~n ~mbodiment and described wi~h reference to said embodimen~.
~ig. 1 is a partial view on a blow molding machine ~ccording to the invention, where ~ome devices thst do not pertain to the invention, for 1nst~nce gearing and control cabinets, have been omitted;
~ig. 2 shows a 6ection taken from Fig. 1 on an enlarged ~c~le in compa~ison with Fig. l;
~ig. 3 6how6 a cycl~ time diagram.
1 gener~lly designates a ~eating path on which an endless conveyor device, such as a chain 2, runs over de~lection pulley~ 3, 3'. Chain 2 carries outwardly pro~ectin~ arm~ 4, of which only a ~ew have been drawn in. The ends of arm6 4 are fo~med a5 parison mounting6, e.g. in the form of ret~ining mandrel~ which are put lnto rotation during the advance movement. A parison taken from a 6upply device 1' can be attached onto each of retaining mandrel~ 5. 6, 6~, 6~l ...
6n de6ig~ate heating means arranged in spaced-ap~rt relation6hip along the heating path, for lnstance, infrared radiators whose radiation will externally heat the parisons which have been attached onto mandrels S. The drawing just show6 heating means arranged along a side of the conveyor 2192~q3 device 2, but these mean6 may also be po6itioned next to the advance run and the return run of chain 2 in the illu~tration.
Each heating path has associated therewith at lea~t one blow path generally designated ~y 7, on which in the illu6trated c~se a blow mean~ 8 i8 arranged with a blow mold ~' having e.g. four respective oavitioo or mold cavitie~. A ~low path 7 fu~ther includes ~ ch~in 10 ~hich ~otat6s ~round deflection chain wheel6 9, 9' in the d~rection of the ~rrow and from which the blown hollow pla~tic article6 are removed. In the case of the illustrated machine a heatlng path 1 operates along two blow paths 7, 7a, t~s 1~6t-mentioned blow path being equipped with a blow means 8a, which is identical with blow mean~ 8, and with deflection pulleys 9a, 9a' and a chain 10~ runn~ng around pulley~ 9a, 9a'.
Tran6fer device~ 11, lla which in controlled fashion remove the par~on~ which have been heated to blow temperature from the deflection portion of the heating path and put them on chain 10 of the blow path or ch~ins 10, lOa of blow paths 7, 7~ are interpo6ed between the end of the heating path 1 ~t the left side in the drawing and the beg~nn1ng of the blow paths 7, 7~ at the right ~ide in the drawing, i.e. between deflection pulley 3 of heating path 1 and deflection pulley6 9, ga of blow path 7, illustrated on an enlarged ~cale in Fig. 2. These tran~fer devices 11, lla are o~ such a structure that on the heating path they grip a plurality, according to the illustxation, for example, a set of four parisons at the same time, remove th~m from their retaining mandrels ~nd pivot them over chain6 lo, lOa of the blow path(~). To thi~ end, the illustrated lev~r-~haped transfe~
devices ll may e.g. have provided th~reon grippers 12 which opexate mechanically or pneumatic~lly (negative pressure).
~lY2sa3 As chown in the drawings, the one tran6fer device, e.g.
transfer device 11, grip~ with its g~ippers, e.g. grippers 12, 12', 12", 12"', ~ ~et of ~ve~al pari60ns, e.g. foux pari~ons 13, 13', 13", 13/", wheneve~ 6aid parisons are equally spaced apart in the deflection posit~on on deflectlon pulloy 3 of heating path l. In thi~ position, i.e. whe~ the conveyor devic~ 2 is deflected ~ the deflection pulley 3, the pitch between the parisons 13 and their retaining mand~el6, ~espectively, becomes greater because the conveyo~-devlce deflection radiu6 r of pulley 3 is smaller than the radiuc R which is de~cribed by the circul~r arc through the center axes of the parisons at~ached onto the end~ of ~rms 4.
This mean6 that as soon as the predetermined number of pa~isons on their arms 4 have re~c~ed the deflection pulley and all, e.g. four parisons at a t~me, occupy an angle e~ually divided by the center pl~ne M on the deflection pulley 3, the parisons will be transferred from the heating path onto the blow p~th if the length of arm~ 4 ~nd thus the deflec~ion radius of the parison~ a~Q dimensioned such that, when the take-ovsr position has been reached, the distance between the pa~isons is equal to the pltcb of the mold6 of mold cavities in the blow mold or blow mold~.
The conveyor device 2 is expediently moved cyclicly in the direct~on of the arrow, i.e. each advance movement i~
followed by a standstill pe~iod. Adv~nce and stand~till periodc on the heating path may, for in6tance, amount to 0.2 s each.
Thus, the parisons are removed by the transfer device 11 in spacsd-ape~t relationship ~rom the con~eyor device 2 ~nd ~re transferred to the chain lo of blow path 7, the spacing of said parisons corre6ponding to the one of the blow mold cavitles in one or a plurality of blow molds that are arranged side by side.
The conveyox device o~ the blow path, e.g. chain 10, i6 also moved in t1med fashion, ~nd the parison8 are tran6ferred f~om the conveyor device 2 to the conveyor device 10 wheneve~ the two devices have a 6tandstill period at the same time o~
~lmost ~t the same time. The advan~e and 6tandstill ~eriod~
o~ chain 10, however, can be ~aried within ce~tain limit~, since th~y are independent of tho6e of the heatlng path, and can be adapted to the blow cycle time, i.e. the time noeded fo~ ~eeding a blow mold with one ot 8 plurality of p~ri~on~
until the ~emoval of the hollow pla~tic art1cles blown. There i8 enough time ~or such an operation because after each gripping of e.g. fou~ parisons at an advance and st~nd6till time of 0.2 s each, an ~dvanae time of 0.2 s x 4 ~ a ctand6till time of 0.2 s x 4 = a period of 1.6 8 will pa~s on the heating path untll there are again four pari60n~ to be grippsd on the portion of the deflection pulley 3 fo~ ~emoval purposes ~nd ~or the pivotal movement of the t~ansfer devices which, of course, also needs some time, though a short one.
This ratio will be fu~ther improved in favo~ of a longer time interval for gripping the parisons and for transferring and processing said parisons in the blow path ~f, in accordance with the illustratlon, a h~ating path 1 operates on two blow paths 7, ~a, because in such-a case the transfer dovics 11, for instance, will not grip the next four pari~3ons which have been precycled fo~ deflection after the parisons have been transferred to chain 10, but only those four parisons following the n~ct ones, the above-mentioned parisons which have been precycled after the transfer are gripped by the transfer device lla and moved onto blow path 7a.
Hence, in the illustrated embodiment the cycle r~tio wlll be 4 : 1 if a cycle consists of an advance time and a ~tandstill time. This mean~ that one cycle is passed on the blow path at the ,same time at which four cycles a~e passed on t~e heating 219250~
path 1. An atte~pt is made in the diagram of Fig. 3 to explain this proce6s; it i6 here a~sumed, but not imperative, that a cylce i~ also divided on the blowh path into two section6 of equal length, namely advanc~ time and ~tand6till time. As can be seen, on the he~ting path 1, four cycles th~t consi6t of advance (v) ~nd 6tandstill (s) are needed to brin~
four pa~is~n6 on the deflection portion into the positlon required ~or a txansfer onto the blow path. It ~ here important that the standst~ll (s) of the conveyo~ device 2 of the he~t~ng path 1 and the ctandstill (S') of the chaln 10 of the blow path 7 overlap to ~uch an extent that both de~ice~
have a ~tandstill pe~iod at the sams time, the standstill period o~ chain 10, however, being pos~ibly longer than that of conveyo~ device 2. During the standstill period of chain 10, it is not only the parisons already positioned on the heating path, in the illustrated ~as~ fou~ parisons, th~t are removed from ~aid path and put ~n chain 10, but four parl~on~
that a~e po~itioned between the opened blow mold parts are g~ipped by the closing mold, blown, cooled and then ~emoved from the mold a~ blown hollow articles. It would even be possible to cyclicly move the conveyor device 2 of heating path 1 onw~rds a~ter a transfer device has been li~ted, i.e.
even before the pari60n6 have been put on the conveyor device 10 or lOa of blow path 7, 7a. Thereupon, an advance movement (V) of four par1son6 takes place on the blow path between or toward6 the blow mold halves, which were opened 1n the meantime, and the ti~ing cycle begins anew. The difference is that in the stralght section of the he~ting p~th the p~ri60ns which pa~s through the heating devices in close pitch ha~e been given, on the deflection portion, a g~eater spacing from one another (- pitch) which corresponds to the ~itch of the mold cavities on the blow p~th, while the pari60ns on said blow path do not change their pitch, but ~aintain lt, since in the case of the heating path the de~lection radius of the conveyor device 2 is ~maller than the ~adiu6 described by the 21~ZS03 _ g parisons on a~ms 4, while on the blow path the de~lection ~adius i8 equal to the one described by the pari~on~ carried by chain 10. If according to the llluxtration in Fig. 1 a heating path 6erves two blow paths, the parison6 are transferred from the heat~ng path 1 to the blow path 7 not durlng the standstill period of the eighth cycle, but only du~ing that of the twel~th cycle on the deflection p~th, i.e.
twice the amount of time i8 available ~or th~ ~dvance movement and th~ transfer o~ the parison6 into the mold cavitiec and fo~ the blowing and cooling opera~ions.
As can be seen, this cystem is very flexible because, e~pecially on the blow path, a cycle ne~d not cons~et of advance and standstill times of the ~ame length. To g~in time for thick-walled hollow plastic articles for blowing and coollng operations in the blow mold, lt is e.g. possi~le to interpose a co-called urgent advance between two s~and6t~11 timos, i.e. to p~olong the standstill tlmes, and it 15 equally pos~ible to prolong the ~dvance time accordingly, e.g., ~n orde~ to gain a longer cooling or compensating time for the paxison6 transferred to the blow path prior to their int~oduction into the blow mold. As is gene~ally known, the reheat method has certain difficulti~s in evenly distrlbuting the heat, which ha6 been applied to the su~face of the pa~i60ns from the outside, ac~o~s the entire cross-section of the parisons down to the inner wall, which is quite easily accomplished when the heat has enough time to propagate across the cross-section evenly.
Moreover, the machine according to the invention is flexible with respect to the number and arrangement of the blow molds and the size of the mold cavities, especi~lly when a heating path serves two blow paths. For in6tance, ~t is possible, of cours~ within certain limits, to produce sm~ller plastic hollow articles of a greater wall thlckness on one blow path _, ~nd corre6pond~ngly greater and thu6 thinner-wallad hollow plastic article~ on the ~econd blow p~th from the same p~rison~ that have been h~ated on the heating path.
_______________________________________________________ The present invention relate~ to the production o~ plastic hollow articles in a spec~al type of blow molding process wherein pa~ison6 made in an in~ection molding proce~s are taken from a supply device and heated on a hoating path to blow tQmperature and are subsequently transferred into one or a plurality of blow molds in whlch they are blown to form hollow pla~tic articles of a 6hape and size predetermined by the mold cavity of the blow mold, subsequently cooled and then removed. Such a method in which cold parison~ that have b~en removed from a supply device are aga1n heated up to blow t~mperature is mo6t of the time called "reheat m~thod".
To be able to heat the individual par~60ns evenly up to blo~
temperature over their entire length and above all o~er their entire cross-section, and since the heat penetrates through the cross-section only at a relatively slow pace, the pari~ons mostly move on 8 long heating route along a straight or circular p~th on which spaced apart heating units, mostly i~rared radiators, are arranged, the portions of the path between the heating units being so-called compensating or cooling sections in which the heat, which has externally been ~pplied to the parisons, has enough time to penetrate through the cross-section. Moreover, these sections are to ensure that the external wall of the parison i6 not overheated, - 21925~3 -which happens quite often wlth many plastics that are sens~tlve with respect to the 60-called proce~s window.
Such a ~ystffm does normally not present any difficulties in cases where only one parison i~ transferred ~nto a blow ~old one at a time after having passed throug~ the heating path (e.g. EP 0 387 735 Al). By contrast, if pari~onc are to be transferred into a plu~ality of blow molds arranged on a spec~al blow path 60 as to incr~ase the output snd thu~
enhance the economlc e~ficiency of a reheat ~ystem, the di~ficulty ari~es that th~ pari~ons are ~o move along the heating p~th in A relat1vely close pitch for an e~ficient exploitation of the radiation emitted, while the pitch of th~
cavities of the blow molds has to ~e adapt~d to the volume of the blown ~ollow articles and thu6 to the size o~ the blow moldc with their cavitie6 or ~old cavities and cooling chaDnels, i.e. the parison~ are to pass along ~hs heating path in ~elatively close pitch, whereas the blow mold ca~ities mu~t be acco~mo~Ated on the blow path in wider p tch in comparison therewith.
DE 31 30 129 A1 de~cribe~ this problem and suggests, as the solution, a heating wheel which rotate~ between heating boxes ~ixedly arrsnged on the outer circumference with a clo~e pitch ~or the parison6 or the retAinin~ mandrels receiving said parisons, from which wheel they are trans~erred by a tran6fer wheel to a blow wheel on which the blow molds ere arranged in a pitch adapted to the size of said molds. As for the 6uggestion made in DE 31 30 129 Al, a transfer is possible for the rea~on that at the beginning not each of the retaining mandrels is equipped with a parison fxom the supply device, but only e.g. the first, third, fifth, 6eventh mandrel dnd then after ~ complete rotation of the h~ating wheel every second, ~orth, sixth, eighth ... retaining mandrel, and a paricon i~ transferred accordingly into a blow -mold only after two rotations. since a new parison is simultsneou61y put onto every po6ition on the heating wheel that has b~come free due to transfer to the blow whesl, with the parison being tran~ferred into a blow mold on the blow wheel ~fter t~o rotations, the m~chine operates continuously, and since it i6 only every second pari~on that is transf~rd from the ~oating wheel to the blow wheel ~n continuou~
sequenre, the pitch on the blow wheel can be twice a~ great ~s ~hat on the heating wheel. o~ cour~e, in this method every pa~ison can e.g. pa58 through the heating path three tLmes be~ore being transferred to the blow wheel, and the blow mold pitch can be chosen accordingly.
Th16 mothod, however, has, e.g., the disadvantage that in thi~ sy6tem, too, only one blow mold including a cavity can be filled with a pari~on one at a time and al~o that every parison hss to pass through two rotation6 of the heating wheel before being removed from the he~ting wheel and transferred to the blow wheel, with the effect that the heating p~th consi6ts of two equal sections, 60 that, as ~ar as a heating operation up to the blow temperature is conc~rned, there i6 no pos6ibility of adaptively ~hanqing ~he heating conditions and the compensating and/or cooling section~ between the heeting devices during the ~econd run in compari~on with the first ~un.
Moreove~, a machine which operates in accordance with this known system requires noticeably more space ~or the same output.
It has therefore been the object o~ the p~esent invention to prrovide a reheat type blow molding machine with the aid of which it i6 not only po~ible to guide the parisons in close pitch on the heating path past the heating section~ and the inte~po6ed compen6ating and/or cooling sections, while the '~192sn3 blow mold or blo~ mold cavity pitch on the blow path i6 independent of the pitch of the pari6cns on the heating path, but with which ~ plurallty of blow mold~ ~n th~ blow path or one or a plurality of blow mold6 with a plurality of blow cavitie~ can simultaneously be equipped with parison~ which c~n simultan~ou61y be blown to form hollow pla~tic article~.
This ob~ect of the lnvention is sol~ed ~ith the means de~ined in p~tent clatm 1. The subclaims relate to expedlent embodiments o~ the inventive idea. The invention 18 illus~rated in the drawings wi~h re~erence to ~n ~mbodiment and described wi~h reference to said embodimen~.
~ig. 1 is a partial view on a blow molding machine ~ccording to the invention, where ~ome devices thst do not pertain to the invention, for 1nst~nce gearing and control cabinets, have been omitted;
~ig. 2 shows a 6ection taken from Fig. 1 on an enlarged ~c~le in compa~ison with Fig. l;
~ig. 3 6how6 a cycl~ time diagram.
1 gener~lly designates a ~eating path on which an endless conveyor device, such as a chain 2, runs over de~lection pulley~ 3, 3'. Chain 2 carries outwardly pro~ectin~ arm~ 4, of which only a ~ew have been drawn in. The ends of arm6 4 are fo~med a5 parison mounting6, e.g. in the form of ret~ining mandrel~ which are put lnto rotation during the advance movement. A parison taken from a 6upply device 1' can be attached onto each of retaining mandrel~ 5. 6, 6~, 6~l ...
6n de6ig~ate heating means arranged in spaced-ap~rt relation6hip along the heating path, for lnstance, infrared radiators whose radiation will externally heat the parisons which have been attached onto mandrels S. The drawing just show6 heating means arranged along a side of the conveyor 2192~q3 device 2, but these mean6 may also be po6itioned next to the advance run and the return run of chain 2 in the illu~tration.
Each heating path has associated therewith at lea~t one blow path generally designated ~y 7, on which in the illu6trated c~se a blow mean~ 8 i8 arranged with a blow mold ~' having e.g. four respective oavitioo or mold cavitie~. A ~low path 7 fu~ther includes ~ ch~in 10 ~hich ~otat6s ~round deflection chain wheel6 9, 9' in the d~rection of the ~rrow and from which the blown hollow pla~tic article6 are removed. In the case of the illustrated machine a heatlng path 1 operates along two blow paths 7, 7a, t~s 1~6t-mentioned blow path being equipped with a blow means 8a, which is identical with blow mean~ 8, and with deflection pulleys 9a, 9a' and a chain 10~ runn~ng around pulley~ 9a, 9a'.
Tran6fer device~ 11, lla which in controlled fashion remove the par~on~ which have been heated to blow temperature from the deflection portion of the heating path and put them on chain 10 of the blow path or ch~ins 10, lOa of blow paths 7, 7~ are interpo6ed between the end of the heating path 1 ~t the left side in the drawing and the beg~nn1ng of the blow paths 7, 7~ at the right ~ide in the drawing, i.e. between deflection pulley 3 of heating path 1 and deflection pulley6 9, ga of blow path 7, illustrated on an enlarged ~cale in Fig. 2. These tran~fer devices 11, lla are o~ such a structure that on the heating path they grip a plurality, according to the illustxation, for example, a set of four parisons at the same time, remove th~m from their retaining mandrels ~nd pivot them over chain6 lo, lOa of the blow path(~). To thi~ end, the illustrated lev~r-~haped transfe~
devices ll may e.g. have provided th~reon grippers 12 which opexate mechanically or pneumatic~lly (negative pressure).
~lY2sa3 As chown in the drawings, the one tran6fer device, e.g.
transfer device 11, grip~ with its g~ippers, e.g. grippers 12, 12', 12", 12"', ~ ~et of ~ve~al pari60ns, e.g. foux pari~ons 13, 13', 13", 13/", wheneve~ 6aid parisons are equally spaced apart in the deflection posit~on on deflectlon pulloy 3 of heating path l. In thi~ position, i.e. whe~ the conveyor devic~ 2 is deflected ~ the deflection pulley 3, the pitch between the parisons 13 and their retaining mand~el6, ~espectively, becomes greater because the conveyo~-devlce deflection radiu6 r of pulley 3 is smaller than the radiuc R which is de~cribed by the circul~r arc through the center axes of the parisons at~ached onto the end~ of ~rms 4.
This mean6 that as soon as the predetermined number of pa~isons on their arms 4 have re~c~ed the deflection pulley and all, e.g. four parisons at a t~me, occupy an angle e~ually divided by the center pl~ne M on the deflection pulley 3, the parisons will be transferred from the heating path onto the blow p~th if the length of arm~ 4 ~nd thus the deflec~ion radius of the parison~ a~Q dimensioned such that, when the take-ovsr position has been reached, the distance between the pa~isons is equal to the pltcb of the mold6 of mold cavities in the blow mold or blow mold~.
The conveyor device 2 is expediently moved cyclicly in the direct~on of the arrow, i.e. each advance movement i~
followed by a standstill pe~iod. Adv~nce and stand~till periodc on the heating path may, for in6tance, amount to 0.2 s each.
Thus, the parisons are removed by the transfer device 11 in spacsd-ape~t relationship ~rom the con~eyor device 2 ~nd ~re transferred to the chain lo of blow path 7, the spacing of said parisons corre6ponding to the one of the blow mold cavitles in one or a plurality of blow molds that are arranged side by side.
The conveyox device o~ the blow path, e.g. chain 10, i6 also moved in t1med fashion, ~nd the parison8 are tran6ferred f~om the conveyor device 2 to the conveyor device 10 wheneve~ the two devices have a 6tandstill period at the same time o~
~lmost ~t the same time. The advan~e and 6tandstill ~eriod~
o~ chain 10, however, can be ~aried within ce~tain limit~, since th~y are independent of tho6e of the heatlng path, and can be adapted to the blow cycle time, i.e. the time noeded fo~ ~eeding a blow mold with one ot 8 plurality of p~ri~on~
until the ~emoval of the hollow pla~tic art1cles blown. There i8 enough time ~or such an operation because after each gripping of e.g. fou~ parisons at an advance and st~nd6till time of 0.2 s each, an ~dvanae time of 0.2 s x 4 ~ a ctand6till time of 0.2 s x 4 = a period of 1.6 8 will pa~s on the heating path untll there are again four pari60n~ to be grippsd on the portion of the deflection pulley 3 fo~ ~emoval purposes ~nd ~or the pivotal movement of the t~ansfer devices which, of course, also needs some time, though a short one.
This ratio will be fu~ther improved in favo~ of a longer time interval for gripping the parisons and for transferring and processing said parisons in the blow path ~f, in accordance with the illustratlon, a h~ating path 1 operates on two blow paths 7, ~a, because in such-a case the transfer dovics 11, for instance, will not grip the next four pari~3ons which have been precycled fo~ deflection after the parisons have been transferred to chain 10, but only those four parisons following the n~ct ones, the above-mentioned parisons which have been precycled after the transfer are gripped by the transfer device lla and moved onto blow path 7a.
Hence, in the illustrated embodiment the cycle r~tio wlll be 4 : 1 if a cycle consists of an advance time and a ~tandstill time. This mean~ that one cycle is passed on the blow path at the ,same time at which four cycles a~e passed on t~e heating 219250~
path 1. An atte~pt is made in the diagram of Fig. 3 to explain this proce6s; it i6 here a~sumed, but not imperative, that a cylce i~ also divided on the blowh path into two section6 of equal length, namely advanc~ time and ~tand6till time. As can be seen, on the he~ting path 1, four cycles th~t consi6t of advance (v) ~nd 6tandstill (s) are needed to brin~
four pa~is~n6 on the deflection portion into the positlon required ~or a txansfer onto the blow path. It ~ here important that the standst~ll (s) of the conveyo~ device 2 of the he~t~ng path 1 and the ctandstill (S') of the chaln 10 of the blow path 7 overlap to ~uch an extent that both de~ice~
have a ~tandstill pe~iod at the sams time, the standstill period o~ chain 10, however, being pos~ibly longer than that of conveyo~ device 2. During the standstill period of chain 10, it is not only the parisons already positioned on the heating path, in the illustrated ~as~ fou~ parisons, th~t are removed from ~aid path and put ~n chain 10, but four parl~on~
that a~e po~itioned between the opened blow mold parts are g~ipped by the closing mold, blown, cooled and then ~emoved from the mold a~ blown hollow articles. It would even be possible to cyclicly move the conveyor device 2 of heating path 1 onw~rds a~ter a transfer device has been li~ted, i.e.
even before the pari60n6 have been put on the conveyor device 10 or lOa of blow path 7, 7a. Thereupon, an advance movement (V) of four par1son6 takes place on the blow path between or toward6 the blow mold halves, which were opened 1n the meantime, and the ti~ing cycle begins anew. The difference is that in the stralght section of the he~ting p~th the p~ri60ns which pa~s through the heating devices in close pitch ha~e been given, on the deflection portion, a g~eater spacing from one another (- pitch) which corresponds to the ~itch of the mold cavities on the blow p~th, while the pari60ns on said blow path do not change their pitch, but ~aintain lt, since in the case of the heating path the de~lection radius of the conveyor device 2 is ~maller than the ~adiu6 described by the 21~ZS03 _ g parisons on a~ms 4, while on the blow path the de~lection ~adius i8 equal to the one described by the pari~on~ carried by chain 10. If according to the llluxtration in Fig. 1 a heating path 6erves two blow paths, the parison6 are transferred from the heat~ng path 1 to the blow path 7 not durlng the standstill period of the eighth cycle, but only du~ing that of the twel~th cycle on the deflection p~th, i.e.
twice the amount of time i8 available ~or th~ ~dvance movement and th~ transfer o~ the parison6 into the mold cavitiec and fo~ the blowing and cooling opera~ions.
As can be seen, this cystem is very flexible because, e~pecially on the blow path, a cycle ne~d not cons~et of advance and standstill times of the ~ame length. To g~in time for thick-walled hollow plastic articles for blowing and coollng operations in the blow mold, lt is e.g. possi~le to interpose a co-called urgent advance between two s~and6t~11 timos, i.e. to p~olong the standstill tlmes, and it 15 equally pos~ible to prolong the ~dvance time accordingly, e.g., ~n orde~ to gain a longer cooling or compensating time for the paxison6 transferred to the blow path prior to their int~oduction into the blow mold. As is gene~ally known, the reheat method has certain difficulti~s in evenly distrlbuting the heat, which ha6 been applied to the su~face of the pa~i60ns from the outside, ac~o~s the entire cross-section of the parisons down to the inner wall, which is quite easily accomplished when the heat has enough time to propagate across the cross-section evenly.
Moreover, the machine according to the invention is flexible with respect to the number and arrangement of the blow molds and the size of the mold cavities, especi~lly when a heating path serves two blow paths. For in6tance, ~t is possible, of cours~ within certain limits, to produce sm~ller plastic hollow articles of a greater wall thlckness on one blow path _, ~nd corre6pond~ngly greater and thu6 thinner-wallad hollow plastic article~ on the ~econd blow p~th from the same p~rison~ that have been h~ated on the heating path.
Claims (7)
1. A blow molding machine operating according to the reheat method for producing hollow plastic articles, comprising a heating path for heating cold parisons taken from a supply device, from which path, after having been heated, they are transferred to a blow path at a greater spacing from one another (wider pitch), which corresponds to the spacing of the blow mold cavities, than on the heating path, on which blow path they are introduced into one or a plurality of blow molds and in which blow molds they are blown to form hollow plastic articles of a desired shape, are then cooled and taken from said molds for the accommodation of new parisons, c h a r a c t e r i z e d i n that said heating and blow paths (1, 7) include straight transportation devices (2, 10) guided around deflection devices (3, 9) for said parisons, and that at least along one side of said transportation device (2) heating means (6) are arranged and along one side of said transportation device (10) at least one blow mold (8) is arranged, that said transportation device (2) of said heating path (1) includes arms (4) for receiving said parisons in close pitch, which arms (4) laterally project in such a manner that the deflection radius (r) of said transportation device (2) is smaller than the deflection radius (R) of the mandrel type receiving means on said arms (4), and that for a removal from said heating path and a transfer to said blow path of a plurality of successive parisons at a time, a transfer device (11) is interposed between a deflection portion of said heating path and the section of said blow path (7) that faces said deflection portion, and is controlled such that it grips said parisons and puts them on said blow path whenever on the deflection portion of said heating path said parisons have a spacing corresponding to the spacing of said blow mold cavities on said blow path.
2. A blow molding machine according to claim 1, characterized by a control means which moves said parisons on said heating path (1) and said blow path (7) in cycles which respectively consist of advance and standstill periods (V and S, respectively), and wherein removal from said heating path and transfer to said blow path take place during a standstill period (S) in which a plurality of parisons are positioned on the deflection path of said heating path at equal distances and said conveyor device (10) is simultaneously at a standstill on said blow path in the position in which said parisons are received.
3. A blow molding machine according to claims 1 and 2, characterized by a control means by which at each cycle of said heating path all parisons are advanced by said transportation device (2) by the same amount, but at each cycle of said blow path only so many parisons are advanced by said transportation device (10) as have simultaneously been transferred from said heating path to said blow path.
4. A blow molding machine according to claim 1, characterized in that at both sides of the extension of a center plane (M) through said heating path two blow paths (7, 7a) are provided with one respective transportation device (10, 10a) and with one respectively assigned transfer device (11, 11a).
5. A blow molding machine according to claims 1 and 4, characterized in that said transportation devices (10, 10a) rotate in the same direction.
6. A blow molding machine according to claims 1, 4, and 5, characterized by a control means by which each of said transfer devices (11, 11a) receives from said deflection portion, every second set of parisons which are ready to be taken over on said deflection portion of said heating path (1) and transfers said set to said conveyor device (10, 10a) and said blow path (7, 7a).
7. A blow molding machine according to claim 1, characterized in that the length of said arms (4) which laterally project from said conveyor device (2) of said heating path (1) and the spacing of said retaining mandrels (5) from said conveyor device (2) are defined by the distance of said mold cavities on said blow path (7, 7a).
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19529969A DE19529969C2 (en) | 1995-08-14 | 1995-08-14 | Blow machine for the production of hollow bodies made of plastic using the reheat process |
| CA002192503A CA2192503A1 (en) | 1995-08-14 | 1996-12-10 | Blow molding machine operating in accordance with the reheat method for producing hollow plastic articles |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19529969A DE19529969C2 (en) | 1995-08-14 | 1995-08-14 | Blow machine for the production of hollow bodies made of plastic using the reheat process |
| CA002192503A CA2192503A1 (en) | 1995-08-14 | 1996-12-10 | Blow molding machine operating in accordance with the reheat method for producing hollow plastic articles |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2192503A1 true CA2192503A1 (en) | 1998-06-10 |
Family
ID=25678906
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002192503A Abandoned CA2192503A1 (en) | 1995-08-14 | 1996-12-10 | Blow molding machine operating in accordance with the reheat method for producing hollow plastic articles |
Country Status (2)
| Country | Link |
|---|---|
| CA (1) | CA2192503A1 (en) |
| DE (1) | DE19529969C2 (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE19958435A1 (en) * | 1999-12-03 | 2001-06-07 | Krupp Corpoplast Maschb Gmbh | Method and device for blow molding containers |
| EP1762367A3 (en) | 2005-09-09 | 2008-02-06 | KOSME Gesellschaft mbH | Process and device for transferring of tubular, thermoplastig preforms in a blowmolding machine |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4106886A (en) * | 1977-06-21 | 1978-08-15 | Beloit Corporation | Parison pickers with variable spacing |
| DE3130129C2 (en) * | 1981-07-30 | 1985-12-05 | Krupp Corpoplast Maschinenbau GmbH, 2000 Hamburg | Blow molding machine for blow molding hollow bodies |
| ES2045598T3 (en) * | 1989-03-14 | 1994-01-16 | Bekum Maschf Gmbh | PROCEDURE FOR HEATING INJECTED PREFORMS REMOVED FROM A RESERVE TANK FOR THE SUBSEQUENT BLOWING TO FORM HOLLOW BODIES IN A BLOWING MOLD AND DEVICE FOR BLOW-MOLDING PREFABRICATED PREFORMS. |
-
1995
- 1995-08-14 DE DE19529969A patent/DE19529969C2/en not_active Expired - Fee Related
-
1996
- 1996-12-10 CA CA002192503A patent/CA2192503A1/en not_active Abandoned
Also Published As
| Publication number | Publication date |
|---|---|
| DE19529969A1 (en) | 1997-02-20 |
| DE19529969C2 (en) | 1998-07-02 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Discontinued |