CA1331263C

CA1331263C - Stretch blow molding method and machine

Info

Publication number: CA1331263C
Application number: CA000600467A
Authority: CA
Inventors: Hermann Voss
Original assignee: Individual
Current assignee: Individual
Priority date: 1988-05-25
Filing date: 1989-05-24
Publication date: 1994-08-09
Anticipated expiration: 2011-08-09
Also published as: CN1039211A; DE3817633C2; AR246063A1; DE3817633A1

Abstract

ABSTRACT

Thermoplastic parisons are fed to a distributing station within a circular array of stationary or orbitable stretch blow molds. A mobile or stationary device serves to transfer parisons from the distributing station to those molds wherein the cavities are ready to accept parisons, and a mobile removing device is used to lift finished stretch blow molded articles out of the respective molds and to deliver them to a take-off station. The transferring and removing devices can be assembled into a unit and can be operated in such a way that removal of one or more articles from one or more first molds takes place simultaneously with insertion of one or more parisons into one or more second molds.

Description

~3~ 2a3 The invention relates to improvements in methods of and in machines for making hollow plastic articles, and more particularly to improvements in methods of and in machines for making blow molded articles of thermoplastic material. Still more particularly, the invention relates to improvements in methods and machines which can be resorted to with advantage Eor the making of stretch blow molded articles, namely articles which are obtained as a result of mechanically effected biaxial stretching and pneumatically effected expansion of thermoplastic ~,~
parisons in the cavities of blow molds.
A stretch blow molding machine normally comprises several molds which define cavities for reception of thermoplastic parisons. The molds cooperate with nozzles which serve to inject into the parisons metered quantities of a pressurized fluid, and with mechanical stretching devices which lengthen the parisons prior, during or subsequent to expansion with pressurized fluid. In many presently known machines, the molds are mounted on a turntable which is indexible about a vertical axis so that the molds advance seriatim past a charging station where the cavities of the molds receive thermoplastic parisons. The parisons are thereupon subjected to a mechanical biaxial stretching aetion and are expanded with a compressed fluid to assume a shape conforming to the surfaces bounding the cavities of the respective molds. As a rule, conversion of parisons into hollow plastic articles (e.g., bottles) is completed not later than when the respective mold completes about f ^: ``
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2, ~ 3 three-fourths of a full revolution about the axis of the turntable. The thus obtained plastic articles are removed form the cavities of the respective molds so that each mold is empty not later than when it reaches the charging station.
An advantage of the just outlined conventional method and machine is that the articles can be turned out at regular intervals. The machine will turn out n = 4 articles per revolution of the turntable if the latter supports four equidistant molds.
The speed at which the turntable can be indexed about the vertical axis depends upon several parameters.
One of these parameters is the interval of time which is required to convert the parison in the cavity of a mold into a stretch blow molded article. In addition, the period of time which elapses for each full revolution of the turntable depends upon the length of the interval which is required to insert a parison into the cavity of a mold and upon the length of the interval which elapses to remove a freshly formed hollow article from the respective mold. Thus, if the turntable is in continuous rotary motion, the speed of such movement is dependent upon at least three variablesO On the other hand, if the turntable is driven in stepwise fashion, the length of intervals of dwell is determined by the periods of time which are needed for insertion of parisons and for removal of hollow articles whereas the speed of movement of the stepwise driven turntable between successive stoppages depends upon the period of time which is required to complete the mechanical stretching and the pneumatic blowing operation, i.e., the conversion of a parison into a hollow article, as well as upon maximum permissible acceleration and deceleration of the molds.
The turntable cannot be subjected to abrupt acceleration or deceleration because this could adversely affect the positions of parisons in the respective mold cavities.
The peripheral speed of the continuously or intermittently rotating turntable is inversely proportional to its diameter. All of these factors prevent a conventional stretch blow molding machine from turning out a large, or even a relatively large, number of articles per unit of time.
~ nother drawback of stretch blow molding machines which employ continuously or intermittently rotating turntables for the molds is that the supplying of hot waterl coolant, compressed fluid, electric current and parisons to as well as removal of hollow articles from the cavities of molds presents numerous problems.
For example, it is necessary to provide means for conveying electric current between stationary and mobile parts, and the same holds true for the means which serve to supply a pressurized fluid (e.g., compressed air) for expansion of parisons in the cavities of the respective molds, to supply hot water and to supply a suitable coolant. Additional serious problems arise in connection with the sealing of paths for the flow of pressurized fluid into the parisons which are confined in the cavities of moldsO The electrically operated monitoring and signal generating devices on the turntable must transmit signals to stationary parts outside of the .. l' j .;',, .. :. . :. . ..

turntable. All this contributes to the bulk, cost and complexity of conventional machines.
S~ill another drawback of conventional machines is that they cannot simultaneously produce two or more different types of hollow stretch blow molded articles.
Thus, each and every mold is provided with the same cavity and each mechanical stretching device is the same as all other devices. On the other hand, the demand for blow molded hollow thermoplastic articles of all sizes and shapes has grown beyond all expectations so that there exists and urgent need for methods and machines which can be relied upon to turn out large numbers of such articles per unit of time. One of the reasons for growing popularity of hollow thermoplastic articles is that their making and disposal are satisfactory for -~
- ecological reasons.
One feature of the present invention resides in -the provision of a method of manipulating thermoplastic parisons and blow molded articles ~including stretch blow molded articles). The method comprises the steps of feeding parisons to a distributing station, positioning a plurality (namely at least two) of blow molds around the distributing station, transferring discrete parisons from the distributing station into discrete molds, converting parisons in the respective molds into blow molded articles, and removing the articles from the respective molds.
; The step of removing an article from a mold can immediately precede the step of transferring a parison into such mold, i.e., the step of introducing a parison .

s~ ~ 3 into the then empty cavity o a mold can follow, practically instantaneously, the evacuation of a freshly formed article from ~he same mold.
Each step of converting a parison in one of at least two molds can take place simultaneously with the : `
step of transferring a parison into the other of the at least two molds, and vice versa.
The transferring step can include conveying the parisons along an arcua~e path, particularly along an endless annular path (such as a circular path) prior to entry of parisons into molds. The removing step can include transporting articles from the respective molds toward or away from the center of the annular path.
The positioning step can include placing the `: molds in a circle around the distributing station, and the transferring step can include clamping the parisons at the distributing station and delivering the thus clamped parisons to the molds.
The removing step can include lifting articles out of the respective molds, In accordance with a presently preferred embodiment, the method further comprises the step of holding the molds against movement relative to the distributing station in the course of the feeding, transferring, converting and removing steps (~or example, the molds ean be fixedly mounted on a stationary support), and the step of transferring a parison into one of the molds can take place simultaneously with conversion of a parison into an article in another mold.
The transferring and removing steps can include .--~

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preferably continuously moving at least one conveyor between the distributing station and the molds t and providing the at least one conveyor with first facilities (e.g., first tongs) for accepting parisons at the distributing station and for inserting parisons into molds, and with second facilities (e.g., second tongs) ;~-for accepting articles from molds. ` ~-The transfPrring step can further include ~ ~delivering parisons from the distributing station to the ~ "
molds in a predetermined sequence (i.e., in accordance with a predetermined pattern), and the removing step can further include evacuating articles from molds in a predetermined sequence.
The transferring step can involve the use of ;
mobile tongs for discrete parisons, and the removing step can include lifting articles out of the respective molds and delivering lifted articles to an article storing and/or evacuating facility (e.g., to a belt conveyor for plastic bottles, vials or like containers).
It is also possible to select the transferring step in such a way that it involves simultaneously withdrawing a plurality of parisons from the distributing station. The removing step can include simultaneously removing articles from at least two molds.
The transferring step can include pneumatically transferring (either by suction or with a pressurized fluid) parisons from the distributing station to the ~--molds. Analogously, the removing step can include `~
pneumatically conveying (by suction or with a pressurized fluid~ articles from the molds to storage or to a ~ J~
take-off conveyor. Alternatively, the transferring step can include conveying parisons by gravity feed, and the removing step can include evacuating articles from the respective molds by gravity feed. It is also possible to rely on a combination of gravity feed and pneumatic conveying, either for transfer of parisons to the molds and/or for the removal of articles from the respective molds.
Another feature of the invention resides in the provision of a machine for manipulating thermoplastic parisons and blow molded articles, particularly stretch blow molded articles. The improved machine comprises means defining a distributing station, means for feeding parisons to the distributing station, a plurality of blow molds which are disposed around thé distributing station, means for transferring parisons from the distributing station into molds for conversion into blow molded articles, and means for removing articles from the molds.
The machine further comprises a support for the molds.
The support can be stationary, and the transferring means ;~ can be mounted for movement relative to the distributing station and relati~e to the molds on the support.
Alternatively, the machine can comprise means (such as a mobile support in the form of a turntable) for moving the molds relative to the distributing station. The moving means can define for the molds a predetermined path, and the transferring means of such machine can comprise means for delivering parisons into molds in a first portion of the path. The removing means of such machine preferably comprises means for evacuating articles from molds in a - ~

~ ~ r~ 3 different second portion of the path.
The transferring means (e.g., in the form of one or more chutes) can be s~ationary relative to the support. Alternatively, the machine can employ ~ -transferring means which is movable relative to -the support. The movable transferring means can comprise tonys for parisons and means for moving the tongs between the distributing station and the molds. The arrangement can be such that the transferring means is equipped with tongs for simultaneous retention of two or more parisons.
The means for moving the tongs can be designed to move the tongs at an at least substantially constant speed. -~
The removing means can be provided on the transferring means or vice versa. ~-: . , .
In accordance with a presently preferred embodiment, the transferring means comprises tongs for parisons and means for moving the tongs between the distributing station (where the tongs receive parisons) and the molds (where the tongs are relieved of parisons).
Such machine can further comprise means for controlling the moving means. The transferring means of this machine can comprise a lever having a plurality of arms and means -for pivoting the lever about a predetermined axis which is disposed between the arms. The tongs are provided on ;
one of the arms, and the removing means is provided on another arm. The controlling means can comprise means for circulating the axis along a substantially circular ;
path about the distributing station. Each of the arms can include a first portion or section which is pivotable about the axis and a second portion or section which i9 _ g _ :
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pivotable and/or otherwise movable relative to the first portion or section. The tongs and the removing means are carried on the second portions or sections o the respective arms. The controlling means can be designed to maintain the removing means in register with an article-containing mold and to simultaneously maintain the tongs in register with a parison at the distributing station.
The molds of the improved machine are open-and-shut molds. Each such mold can comprise a plurality of sections which define a cavity for parisons and blow molded articles. At least one section of each mold is movable relative to at least one other mold section between an open position in which a parison is insertable into or an article is removable from the cavity, and a closed position in which the parison or the article is confined in the cavity. Means is provided for moving the at least one section of each mold between open and closed positions, and the machine further comprises means for controlling the operation of such moving means. The controlling means can comprise cam and follower means.
In order to simplify the controlling means, the latter preferably further comprises a rotor or other suitable means for moving the cam means relative to the molds.
Such cam means can include at least one endless cam which surrounds the distributing station. The rotor is preferably driven to rotate about an axis at the , i distributing station. Such rotor can include a horizontal end wall and an annular wall which is mounted on or is integral with the end wall. The cam and . ,.. , .. : . , . , . ~ .. .. ... ~

,, follower means of the controlling means can include a cam and follower unit on the end wall to move the one section ~ ~-of each mold between open and closed positions, and the annular wall of the rotor can be provided with or can -~
carry one or more additional cam and follower units to regulate the operation of means for converting parisons into hollow articles.
Each cam can constitute a groove cam.
The converting means can include valves which serve to admit pressurized fluid into parisons in the cavi~ies of molds and means for actuating the valves.
Such actuating means can receive motion from a follower which tracks one of the cams on the annular wall of the rotor. The actuating means can comprise holders for the valves and means for reciprocating the holders and their valves relative to the parisons in the cavities of the --molds in response to rotation of the rotor and resulting displacement of the followers tracking the cams. Each holder can be provided with means for sealing the parisons in their mold cavities to prevent the escape of gaseous fluid from parisons when the valves are open.
The converting means can further include means for mechanically stretching parisons in the cavities of the molds, and such stretching means can receive motion from the follower tracking one of the cams on the annular wall of the rotor. The converting means of such machine can further comprise a step-up transmission which is interposed between the stretching means and the respective follower. Such transmission can comprise an input element which is operatively connected (e.g., by a ,. :

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2 ~ 3 motion transmitting link~ with the respective follower, an output element which is operatively connected with the respective stretching means, and an intermediate element which receives motion from the input element and serves to transmit motion to the output element in such a way that the extent of movement of the output element exceeds the extent of movement of the input element. At least one element of the transmission can include a belt and pulley drive. The belt and pulley drive of the intermediate element can be designed in such a way that it comprises a larger-diameter pulley which is driven by the input element, a smaller-diameter pulley which serves to drive the output element, and an endless Elexible element which is trained over the pulleys. The transmission can Eurther comprise a friction-operated coupling device between the input element and the respective follower and~or a friction-operated coupling device between the output element and the stretching means.
The cam which controls the actuating means for the valves can be provided with a single lobe which is tracked by followers to effect an opening of the respective valves. The flanks of the lobe can make with the remaining portion of the cam angles of 100-135 degrees, preferably angles at least close to 135 degrees.
That cam on the annular wall of the rotor which initiates opening and closing of the valves is preferably installed at a levPl below the cam which controls the movements of the mechanical stressing means. The cam which controls the movements of the stretching means : - ~.. , . : . :. :.: : . ::.:: : .
. ~ ,: . . . : . ,- .: .:: . . : .. , : . .

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~33:~?~3 preferably includes a first section at a level below a second section. The first section is tracked by the respective follower in one position (e.g., inoperative position) of the stretching means, and the second section is tracked when the stretching means for a mold assumes another position (e.g., ~he operative position). The length of the first section can equal or approximate the length of the second section. Gradual transitions are preferably provided between the first and second sections, and such transitions can be inclined relative to the two sections at angles of between 40 and 60 degrees.
The transferring means can comprise at least one chute for parisons. Such chute can have a slope which is sufficient to ensure that a parison which enters the chute can slide by gravity feed toward the cavity of an open mold. It is also possible to provide means for pneumatically and/or mechanically conveying parisons along one or more chutes from the distributing station to the cavities of open and empty molds. For example, the transferring means can comprise a chute for each mold.
Each such chute has an upper end portion adjacent the ~ `
distributing station and a lower end portion adjacent the respective mold. Such transferring means can further comprise gates or other suitable means Eor releasably locking the lower end portions of the chutes so ~s to ensure that a parison can leave the respective chute only , when the adjacent mold is open and its cavity is ready to receive a parison.
The molds can form a complete ring around the ; ` ~

- ~, distributing station. Alternatively, ~he machine can comprise only two, three or another relatively small number of molds. The distributing s~ation can be located at or close to the center of the circular array of molds.
The novel features which are considered as characteristic of the invention are set forth in particular in the appended claims. The improved machine itself, however, both as to its construction and its mode of operation, together with additional features and advantages thereof, will be best understood upon perusal of the following detailed description of certain specific embodiments with reference to the accompanying drawing.
FIG~ 1 is a schematic plan view of a machine which embodies one form of the invention and operates with a ring-shaped array of stationary molds;
FIG. 2 is a schematic elevational view of a second machine wherein the molds are mounted on a rotary support in the form of a turntable;
FIG. 3 is a schematic plan view of a third machine with stationary molds and with a combined parison ~-J
transferring and article removing device;
FIG. 4 is an enlarged fragmentary vertical sectional view substantially as seen in ~he direction of arrows from the line IV-IV of FIG. 3;
FIG. 5 is a developed view of two cams in the machine of FIGS. 3 and 4;
FIG. 6 is a schematic plan view of a third machine wherein the means for transferring parisons to ~he cavities of molds comprises a set of stationary . . ,, i, ~,,.. , .. -. ~ ,,,: - , -:~ ,: - - -.. -.. :, ~.

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chutes; and FIG. 7 is a similar schematic plan view of a fourth machine wherein the transferring means comprises a single chute which can be moved around the parison distributing station.
Referring first ~o FIG. 1, there is shown a stretch blow molding machine including a plate-like support 1 for a set of molds 6 forming a ring 5 around a parison distributing station 2. Parisons 22 are fed to the station 2 by an endless belt conveyor 27 substantially radially of the array of molds 6, and ~-~
finished stretch blow molded articles 9 are removed from molds 6 by a removing device 10 for delivery to a take-off station 3, namely onto the upper reach of an endless belt conveyor 8. The machine further comprises a transferring device 15 which serves to transfer parisons 22 from the station 2 to selected molds 6, for example, in a predetermined sequence. Still further, the machine comprises parison converting means including means for mechanically stretching parisons 22 in the cavities of the respective molds 6 and means for admitting into the parisons metered quantities of a pressurized fluid ~such as compressed air) to ensure that the shape of each article 9 will conform to the shape of the surface bounding the cavity in the respective mold 6.
The distributing station 2 occupies or is close to the center 4 of the circular array 5 which is formed by the molds 6, and the take-off station 3 is outwardly adjacent a marginal portion 7 of the support 1. The conveyor 8 at the station 3 can deliver articles 9 to a 2 ~ ~
magazine. The removing device 10 is designed to lift articles 9 out of the respective mold cavities and to thereupon move the lifted articles along an arcuate or other path on their way toward the conveyor 8 at the take-off station 3. The illustrated removing device 10 is mounted for angular movement about an upright pivot member 11 which is adjacent the marginal portion 7 of the support 1 close to the take-off station 3. The free end of the removing device 10 carries tongs or grippers 12 which can engage a finished article 9 for delivery onto the conveyor 80 The illustrated removing device 10 includes a composite elongated arm which is assembled of several articulately connected sections or portions (portions 13 and 14 are shown in FIG. 13 so that it can move its tongs 12 toward and into register with the cavities of selected molds 6. Once an article 9 has been lifted out of the cavity of the respective mold 6, the removing device 10 is caused to turn about the axis of the pivot member 11 in order to move the tongs 12 above the adjacent receiving end of the continuously or intermittentl~ driven conveyor 8 at the take-off station 3. The machine can be equipped with two or more removing devices 10 each of which is positioned and designed to remove articles 9 from the cavities of an adjacent group of two or more molds 6. Alternatively, or in addition - thereto/ the ring-shaped array 5 of molds 6 can be caused to turn about the distributing station 2 so as to move successive or selected molds 6 into the range of tongs 12 on the composite arm 13+14 of the removing device 10.
The transferring device 15 comprises tongs 24 ~ 3 3 ~ 2 i j at the free end 23 of an elongated composite arm 16 which is turnable about a vertical axis deined by an upright pivot member 18 mounted in a bearing 17 within the array 5 of molds 6. The arm 16 is assembled of several portions or sections (two are shown in FIG~ 1, as at 20 and 21) which are articulakely connected to each other by one or more joints 19. Such design of the transferring device 15 enables its tongs 24 to accept a parison 22 at the distributing station 2 and to transfer the thus accepted parison into the cavity of a selected mold 6.
The means for opening and closing the jaws of the tongs 24 is or can be of conventional design and is not specifically shown in the drawing. The same holds true for the means for opening and closing the jaws or claws of the tongs 12 forming part of the removing device 10.
It goes without saying that the machine further comprises suitable means for pivoting the arm 16 of the transferring device 15 about the axis of the pivot member 18 and for increasing or reducing the distance between the pivot member 18 and the claws of the tongs 24 in order to enable the device 15 to accept parisons 22 at the station 2 and to deliver the thus accepted parisons into the unoccupied cavity of a selected mold 6.
The molds 6 are preferably designed in such a way that biaxial stretching or lengthening of parisons 22 precedes pneumatic expansion of the parisons to complete the conversion of a parison into a hollow article 9, e.g., a bottle, a vial or an analogous con-tainer for flowable media. FIG. 1 shows that each mold 6 comprises two sections 25, 26 at least one of which is movable ;~
~.
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relative to the other so as to assume an open position (in which the tongs 24 can introduce a parison 22 in~o the respective cavity or the tongs 12 can remove a finished article 93 or a closed position in which the parison 22 is properly confined in the cavity and is ready to be acted upon by the stretching means as well as to receive a requisite quantity of a compressed gaseous fluid.
In accordance with one presently preferred embodiment, the molds 6 are stationary, iOe., they are not movable relative to and/or with the support 1. It is then necessary to design the transferring device or devices 15 in such a way that parisons 22 can be transferred from the station 2 into the cavity of any one : of the ring-shaped array 5 of molds 6, and that the removing device or each removing device 10 can lift a inished article 9 from `any selected mold 6. The effective length of the arms of the illustrated devices 10 and 15 can be changed within a range which is necessary to ensure that the tongs 12 can be moved between the take-off station 3 and any selected mold 6, and that the tongs 24 can be moved between the distributing station 2 and any selected mold 6. This applies, of course, if the machine of FIG. 1 employs a single transferring device 15 and a single removing device 10. The manner in which the tongs 24 on the arm 16 of a transferring device 15 can pick up parisons 22 from the feeding conveyor 27 for introduction into the cavity of a selected mold 6, and in which the removing device 10 can lift articles 9 out of mold cavities for ~ `

:;
~ 3 ~ 3 transport to the conveyor 8 at the take-off station 3 can be seen in FIG. 2.
The molds 6 of FIG. 2 are mounted on a support in the form o a turntable 49 which is rotated by a gear transmission 150 receiving motion from a variable-speed electric or other suitable motor 1510 The turntable 49 moves successive or selected molds S to a first location where the arm 16 of the transferring device 15 delivers parisons 22 which are taken off the feeding conveyor 27, `
and to a second location where the molds 6 are opened or are already open so as to enable the removing device 10 to lift the articles 9 out of the respective mold `
cavities and to transfer the thus lifted articles onto the conveyor 8 at the take-off station 3. The molds 6 can be indexed to the two locations one after the other or in any desired sequence. It is also possible to provide two or more locations for delivery of parisons 22 thereto and to provide two or more locations for removal ;
of articles from mold cavities. An advantage of the machine of FIG. 2 is that it can accommodate a large number of molds 6. MoreovPr, this machine renders it possible to employ a transferring device 15 with two or more arms 16 tonly one shown) or with a single arm or two or more tongs 24 (not shown) for simultaneous insertion of parisons 22 into two or more molds 6.
Analogously, the removing device 10 can be designed for simultaneous removal of articles 9 from two or more mold cavities.
Another advantage of the machine of FIG. 2 is that it can be equipped with substantially stationary ~33.~2~
transferring and removing devices 15 and 10, respectively. Thus, the distances which must be covered by the tongs of the transferring device 15 and by the ,, tongs o the removing device 10 are much shorter than the distances which such tongs must cover in the machine of FIG. l wherein the molds 6 are mounted on a stationary or fixed support l. However, the versatility of the machine of FIG. 2 can be considerably enhanced if the devices lO
and 16 are movable relative to the turntable 49 so that they can readily reach any selected mold 6 on the turntable. By superimposing the movements of the devices lO, 15 upon the movements of the turntable 49, the machine of FIG. 2 renders it possible to increase the output by reducing to a minimum the length of intervals which elapse for evacuation of freshly formed articles 9 from the respective mold cavities (as soon as the parison-converting step in a cavity is completed) and by reducing the length of intervals which are required to introduce parisons into freshly emptied molds 6. The turntable 49 can be maintained in motion during insertion of parisons 22 into and during removal of articles 9 from mold cavities, especially if the turntable supports a large number of molds so that its peripheral speed is relatively low.
FIG. 3 shows a modified machine with three equidistant open-and-shut molds 6 disposed in a circle about a distrihuting station 63 for parisons 22. The transferring device 15 of FIGS. l and 2 is replaced with a different transferring device including a conveyor in the form of a lever 52 having two arms extending to ~ 3 ~ r~ ~

opposite sides of a vertical fulcrum 51 which is movable along an endless path indicated by a phantom-line circle 62. Each arm is composed of several portions or sections. Thus, one of the arms includes a first portion or section 53 connected to the fulcrum 51 and a second ~ ~:
portion or section 54 connected to the first section 53 by a pivot member 56. The free end o:E the section 54 carries tongs 55 for removal of parisons 22 from the distributing station 63. The other arm of the lever 52 includes a first portion or section 57 mounted on the fulcrum 51 and a second portion or section 59 which is articulately connected to the section 57 by a pivot member 58. The free end of the section 59 carries tongs 60 for removal of articles 61 from the cavity of the adjacent mold 6. The tongs 60 is movable up and down so as to lift and article 61 out of the cavity of the adjacent mold 6.
The lever 52 can turn about the axis of the fulcrum 51 while the latter travels along the endless circular path 62. The means Eor moving the fulcrum 51 along such path is not shown in FIG. 3. The portions or sections 54 and 59 can pivot relative to the respective portions or sections 53, 57 while the fulcrum 51 is at a standstill and/or while the fulcrum 51 travels along the path 62. The direction in which articles 61 can be removed from the machine of FIG. 3 is indicated by an arrow A. The tongs 60 can deposit articles 61 on a conveyor which moves in the direction of arrow A and perform the function of the conveyor 8 of FIGS. 1 and 2.
The arrangement is preferably such that the lifting of a .

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~ 3~2~3 finished article 61 from the respective mold cavity takes place simultaneously with the engagement of a parison 22 at the distributing station 63 by the tongs 55. Once the introduction of a parison 22 into an open mold 6 is completed, the sections 25, 26 of such mold are closed and the stretching and blowing operations can begin to convert the parison into an article 61. The molds 6 are mounted on a ring-shaped wall member 102 resting on a support 1. The feeding conveyor for parisons 22 is indicated by arrow B.
FIG. 4 shows the means 64 for controlling the movements of mold sections 25, 26 between open and closed positions and the means for converting parisons 22 into articles 61 as well as the means for controlling the opening and closing means for the mold sections 25, 26 and the operation of the converting means.
The controlling means 64 comprises three cam and cam follower units 65, 66 and 67. The unit 67 serves to open and close the sections 25, 26 of the molds 6, the unit 66 serves to regulate the admission of pressurized fluid into parisons 22, and the unit 65 serves to initiate and control movements of stretching members 78 which increase the length of parisons 22 in the cavities of the respective molds 6. The controlling means 64 further includes a cupped rotor 68 which has a horizontal end wall or bottom wall 70 and an annular wall 69 extending upwardly from the end wall 70 and having in its external surface 72 two groove cams 74, 75 forming part of the units 65, 66, respectively. A groove cam 71 in the underside 73 of the end wall 70 forms part of the -unit 67. The hub 112 of the cupped rotor 68 is rotatable in antifriction bearings or in other suitable bearings 113 carried by the support 1.
The support 1 carries the aforementioned ring-shaped wall member 102 for all three molds 6, or a discrete upright wall member 102 for each of the three molds. The wall member or members 102 movably support roller followers of the cam and follower units 65, 66 and 67. The cam 74 receives a roller follower 84 and the cam 75 receives a roller follower 83. The means 76 for moving the parts of the converting means in response to rotation of the cupped rotor 68 relative to the wall member or wall members 102 (i.e., relative to the molds 6) includes a set of links, levers and like parts which receive motion from the followers 83 and 84. It will be noted that the cam 75 for the follower 83 is located at a level below the cam 74 for the follower 84.
The upper follower 84 transmits motion to a compressed-gas connection 77 carrying a holder and actuating means 114 for a valve 200 which must be opened in order to admit pressurized fluid (such as compressed air~ into the parison 22 in the cavity of the respective mold 6. The holder 114 has means for sealingly engaging a nipple 80 of the parison 22 to prevent uncontrolled escape of pressurized fluid during pneumatic expansion of the parison in the cavity of the mold 6. The valve 200 is opened in automatic response to lowering of the holder 114 by the follower 83 into sealing engagement with the nipple 80.
The follower 84 initiates and controls the ,:

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movements of a stretching member 78. A discrete stretching member 78 and a discrete holder 114 is provided for each of the molds 6.
The holder 114 which is shown in FIG. 4 is connected to one end of a pivotable lever 79 which is mounted on the wall member 102, as at 81, and the shorter arm of which is connected to a motion transmitting link 82 receiving motion from the follower 83 in the cam 75.
Relatively small up-and-down movements o the motion transmitting link 82 result in much larger up-and-down movements of the holder 114 and valve 200. The valve 200 opens automatically when the holder 114 is lowered into sealing engagement with the nipple 80-of the parison 22 in the adjacent mold 6. When the admission of a requisite quantity of pressurized fluid is completed, the cupped rotor 68 causes the follower 83 to pivot the lever 79 in a counterclockwise direction (as seen in FIG. 4) so that the holder 114 is lifted above and away from the nipple 80 and the valve 200 closes automatically to terminate the admission of pressurized fluid into the parison 22 (which by then is converted into an article 61). The unit 67 thereupon effects an opening of the respective mold 6 so that the tongs 60 can lift the article 61 out of the mold cavity preparatory to transfer onto the conveyor which advances articles 61 in the ~: :
direction of arrow A.
The follower 84 in the cam 74 is connected with a motion transmitting link 85 which, in turn, can ~ ;
transmit motion to the input element 87 of a step-up transmission 86. The latter further includes an output - 24 - :~
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~33~
element 88 and an intermediate element or transmission 89. The output element 88 can move an entraining member 99 for the stretching member 78 at the respective stretch blow molding station. The purpose of the intermediate element 83 of the transmission 86 is to transform relatively short displacements of the input element 87 into longer movements of the output element 88 and stretching member 78.
A friction-operated coupling device 94 is provided between the motion transmitting link 85 and the input element 87 of the transmission 86~ The input element 87 is a belt drive having two toothed pulleys 90, 91 and an internally toothed belt 93 which is trained over these pulleys. The friction-operated coupling device 94 engages the external surface of the belt 93.
Such external surface is rough to ensure adequate engagement with the coupling device 94. The latter is or can include a friction pad provided on the motion transmitting link 85 and bearing against the external ~o surface of the belt 93.
The output element 88 of the transmission 86 also comprises two toothed pulleys 97 and an endless internally toothed belt 98 which is trained over these pulleys. The belt 98 transmits motion to the entraining member 99 for the stretching member 78.
The intermediate element 89 of the transmission 86 comprises a large-diameter pulley 95 which is coaxial `
with and is non-rotatably connected to the pulley 90 of the input element 87, and a smaller-diameter pulley 97 (e.gO~ an extension of the upper pulley of the output .
: :~: : .
,. ~ ~ ~ , . .,. . . , . :

~ 3 element 88~ which transmits torque to the output element 88. An internally toothed endless belt 96 is trained over the pulleys 95 and 97 of the element 89 to ensure that the stretching member 78 covers a relatively long distance in response to a relatively short upward or downward movement of the coupling device 9~. The entrainin~ member 99 can be a functional equivalent of the coupling device 94, i.e., it can comprise a rough-surfaced friction pad which bears against the rough external surface of the endless toothed belt 98 of the output element 88 to move the stretching member 78 up or down, depending upon ths configuration of that portion of the cam 74 which is then tracked by the follower 84. The entraining member 99 can be fixedly secured to the stretching member 78.
FIG. 4 shows a parison 22 during conversion into an article 61. The stretching member 78 is shown in a retracted position in which its lower end is spaced apart from the bottom wall of the biaxially stretched ~ :
parison 22. The valve 200 is open and admits compressed gaseous fluid into the interior of the parison 22 while the nipple 80 is sealingly engaged by the holder 114. :
The latter can comprise one or more sealing rings which directly engage the nipple 80 of the parison 22 in the cavity of the adjacent mold 6. It is clear that the stretching member 78 is fully extracted from the freshly finished article 61 before the latter is lifted out of or otherwise removed from the cavity of the respective mold .
6. ~t such time, the follower in the cam 71 at the underside of the end wall 70 of cupped rotor 68 maintains : .

-~33~
the sections 25, 26 of the mold 6 in open positions.
The lower end portion of the motion transmitting link 82 of FIG. 4 is guided by a coulisse 100 on the wall member 102, and a second coulisse 101 is provided for the lower end portion of the motion transmitting link 85. The illustrated wall member 102 is assumed to constitute a circumferentially complete or composite enclosure (see FIG. 3) surrounding the three molds 6 which, in turn, surround the distributing station 63 and the path 62 for movement of the fulcrum 51 for the combined parison transferring and article removing lever 52. As mentioned above~ a discrete pair of motion transmitting members 82, 85 is provided for each mold 6O
Howev~r, the cupped rotor 68 and its endless annular cams 71, 74, 75 are common to the three molds 6. The configuration of two of these annular cams is shown in developed view in FIG. 5, namely that of the cam 74 and that of the cam 75.
The configuration of cams 74 and 75 is such that they do not effect an abrupt acceleration or deceleration of the motion transmitting links 82, 85 at ~: the three blow molding stations. It is preferred to ~ ensure that the movements of the links 82, 85 are carried : out at a constant rate which can be readily achieved by appropriate selection of configuration of the cams 74 and 75. As shown in FIG. 5, the cam 75 has a single lobe 103 which causes the corresponding follower 83 to lower a holder 114 into engagement with the nipple 80 of the adjacent parison 22 when the lobe 103 reaches the respective mold 6 while the rotor 68 rotates about its ~ ~ 2 ~ 3 vertical axis. The flanks 104, 105 of the lobe 103 preferably make with ~he plane of the end wall 70 and with the remaining portion 106 of the cam 75 angles of 100-150, most preferably angles of close to or exactly 135.
The cam 74 has a first section 112 at a lower level and a second section with ~nd portions 107, 108 at a higher second level. The section 112 is tracked by a roller follower 84 when the respective stretching member 78 is maintained in raised position. The transitions between the two sections 107-108 and 112 of the cam 74 are preferably smooth and gradual and can make with the - plane of the end wall 70 angles of 40-60 degrees. These transitions are or can be mirror images of each other.
The maximum height of th~ lobe 103 of the cam -~
75 and the difference between the levels of the two sections 107-108 and 112 of the cam 74 determine the extent of vertical movement of the holders 114 and of the stretching members 78, respectively. As a rule, sùch differences will be relatively small in order to avoid excessive acceleration of the motion transmitting links , . ~ .. .
82 and 85.
FIG. 4 further shows a gear 168 which forms ,.,~ ,.~ ., "
part of the means for driving the cupped rotor 68 about its vertical axis. Only three molds 6 have been shown in FIG. 3 for the sake of clarity; the machine of FIGS. 3 and 4 can comprise two, four or more molds without departing from the spirit of the invention.
The conveyor 27 of the means for feeding parisons 22 to the station 2 or 63 can be installed at a "~ ~ `
:, .

.,:: : :
' ~
' ~: -:: .

-~ 3 ~

level above the support 1. However, it is also possible to install the feeding means at a level beneath the support for the molds 6 and to provide suitable means (e.g., a ~echanical elevator or a suction generating device, not shown) for lifting parisons 22 from the level of feeding means beneath the support 1 to a level above the support so that they can be engaged by the tongs 12 or 5s.
FIG. 6 shows that a mobile transferring device (such as the device 15 of FIG. 1) can be replaced by a transferring device 28 including a set of stationary chutes or troughs 29 each having an upper end at the distributing station 2 and a lower end 30 at the respective mold 6. Each chute 29 defines a channel wherein a parison 22 can slide by gravity from the station 2 toward the respective mold 6. The lower ends 30 of the chutes 29 are provided with disengageable (e.g., retractible) locking or arresting devices or gates 31 which arrest the parisons 22 adjacent the respective molds 6 and are automatically retracted as soon as the cavity of the adjacent mold is ready to receive a fresh parison, i.e., as soon as the removal of a freshly formed article is completed.
A parison 22 can leave the discharge end of the feeding conveyor 27 by gravity alone and/or with assistance from suitable mechanical or pneumatic means, e.g., nozzles which discharge compressed air and effect the transfer of parisons from the conveyor 27 into selected chutes 29 and/or promote the advancement of parisons in the chutes. Disengagement (e.g., retraction) ~33~2~

of locking devices 31 can take place in automatic response to opening of the respective molds 6, or with a certain delay following such opening so as to provide an interval of time for evacuation of a freshly formed article 9 or 61 from the mold cavi~y before the locking device 31 opens or is retracted in order to enable the parison 22 to leave the chute 29 and to enter the adjacent mold cavity.
FIG. 7 illustrates a por~ion of a further stretch blow molding machine wherein the means for transferring parisons 22 into selected molds 6 comprises :~
a single chute 33 having an upper end 32 adjacent the distributing station 2 and a lower end provided with a locking device 35. The upper end 32 can turn about a :
vertical axis 34 so that the locking device 35 advances - along an arcuate path adjacent the ring-shaped array of molds 6 which surround the station 2 and are fixedly mounted on the support 1. The means for turning~the single chute 33 about the axis 34 can comprise a stepping motor or any other suitable means which can index the chute 33 through angles of desired magnitude so as to ~ :
move the locking device 35 adjacent that mold 6 wherein the cavity is ready to receive a parison 22. The indexing means is operated in accordance with a :~
predetermined program. The arrangement may be such that opening of a mold 6 automatically entails a movement of the locking device 35 to proper position for opening and ~:
, admission of a parison 22 into the cavity of such mold, ~:
preferably with an automatic delay which is needed to allow for evacuation of the freshly formed article from - -~;:

11 3 ~ 3 ~
such mold.
Parisons 22 can slide off ~he chute 33 and into the adjacent mold cavities by gravity feed (i.e., due to appropriate selection of inclination of the channel in the chute 33), or such admission of parisons into the mold cavities can be assisted by properly distributed and oriented nozzles which discharge jets of compressed air or another suitable fluid. Mechanical introducing means can be used in addition to or in lieu of nozzles for compressed air or another gaseous fluid.
Referring again to FIG. 1, the removing device 10 may but need not necessarily be outwardly adjacent the support 1 for the molds 6. For example, the removing device can be movably installed in the area 4 within the ring-shaped array 5 of the molds 6. Such modification is analogous to that which is shown in FIG. 3 wherein the lever 52 forms part of the means for transerring parisons 22 into molds 6 as well as of the means for removing articles 61 from the cavities of the molds. An advantage of the arrangement which is shown in FIG. 3 is that the removing means including the tongs 60 is nearer to all of the molds 3 than the removing device 10 of FIG.
1. On the other hand, the device 10 of FIG. 1 exhibits the advantage that it can be moved out of the way so that it does not interfere with the delivery of parisons 22 by the feedin~ conveyor 27 and/or with transfer of parisons 22 from the distributing station 2 to the cavities of the molds 6.
It is further possible to modify the improved machine in such a way that the take-off station 3 is ~,, " ~ " ~
, . ~ , . . . .
,~,, . : . .. . .

~3~2 ~3 located in the space 4 within the ring-shaped array 5 of molds 6 which surround the distributing s~ation 2 or 63.
For example, the support 1 of FIG. 1 can be provided with an opening (not shown) and the tongs 12 are then movable to a position above such openin~ to release an article 9 which descends through the opening to be intercepted by a collecting receptacle beneath the support 1 or to descend onto a conveyor performing the function of the conveyor 8 of FIG. 1. Still further, it is possible to provide a conveyor or articles 9 or 61 at a level above the station 2 and to equip the removing device 10 with suitable means for raising freshly removed articles 9 to the level of such overhead conveyor to which the articles can adhere by suction or on which the articles can be held in any other suitable way. The just described mode of removing articles 9 or 61 exhibits the advantage that the removing device 10 or its equivalent must cover relatively short distances from the cavities of the molds 6 to the take-off station at a level above the station 2.
All embodiments of the improved method and all embodiments of the improved machine exhibit the advantage -~
that the number of blow molded articles which can be turned out per unit of time is higher than in heretofore known machines and in accordance with heretofore known methods. The reason is that the parisons 22 are invariably delivered to a central location within the array of molds, irrespective of whether the molds are stationary or are caused to circulate around the parison distributing station. The output of the improved machine is high even if the molds are caused to orbit stepwise `:`

lr~ 3 around the distributing sta-tion so that they are stationary during insertion oE parisons into and/or during removal of finished articles from the mold cavities. It is also wi~hin the purview of the invention to maintain the molds 6 in motion during insertion of parisons and/or during removal of finished blow molded articles.
An important advantage of that embodiment of the improved machine which employs stationary molds (including the machines shown in FIGS. 1 and 3 to 7) is that such mounting of molds simplifies the admission of pressurized fluid, heating liquid, coolant and the supplying of electrical energy to various electrically operated or current-consuming parts on or adjacent the molds. This will be readily appreciated since the conduits which supply pressurized fluid to the holders (such as 114) of valves (such as 200) need not include stationary and moving parts; they can extend all the way from a stationary source of pressurized fluid to the respective holders. All that is necessary is to employ relatively short flexible conduits which enable the holders 114 to move up and down to an extent which is necessary to properly engage their sealing elements with the nipples 80 of the parisons 22 and to permit convenient evacuation of blow molded articles from the mold cavities. Moreover, the construction of means for moving the holders 114 and the stretching members 78 , relative to the molds 6 is simpler and less expensive if such moving means are associated with stationary molds.
It has been found that the life span of sealing elements ~,3~,2~i3 which are used in conjunction with stationary molds is a multiple of the life expectancy of sealing elements which are used to prevent uncontrolled escape of pressurized fluid in machines wherein the molds are in motion during conversion of parisons into hollow articles.
Stationary molds are desirable on the additional ground that this simplifies the design of parts which supply heating and cooling fluids (particularly water) to the molds. It has been found -~
that the versatility and availability factor of the improved machine can be increased hundertfold by resorting to a set of stationary molds with a centrally located parison distributing station. Similar observations apply for the economy of operation of the `~
improved machine. A machine with stationary molds is surprisingly simple, compact and reliable. The controls are simple and inexpensive, and the energy requirements are much lower than those of a conventional machine with orbiting molds. Moreover, the controls are more reliable and their operation is much more accurate than in machines with orbiting moldsO
A further important advantage of the improved machine, irrespective of whether it employs stationary or mobile molds, is that it can be readily set up to turn out two or more different types of blow molded articles in a simultaneous operation. This can be achieved by using identical parisons or by using two or more different types and/or sizes of parisons. The regulation of converting operation is sufficiently simple and 2 ~ ~ ;
reliable to ensure that the wall thickness of each blow molded article matches or closely approximates a desired optimum wall thic~ness. This renders it possible to achieve considerable economies as concerns the consumption of thermoplastic material because the quantity of material which is needed for the making of discrete articles can be calculated in advance with a high degree of accuracy.
Since the controls (including detectors, sensors, adjusters, gauges and others) which are used in a machine with stationary molds are not subjected to extensive stresses and can be fixedly mounted adjacent the parts to be monitored, the machine of the present invention can employ high-quality detectors, sensors and like parts which can monitor the operation of the machine with a heretofore unmatched degree of accuracy.
Therefore, the operation of the improved machine can be regulated by a computerized controlling system. ~owever, it is equally within the purview of the invention to provide the machine with semiautomatic or with manually operable controls. Irrespective of the nature of selected controls (whether programmed, semiautomatic or manual), the machine renders it possible to individually select optimum heating and/or cooling for each mold, to individually select the periods of confinement of parisons in the cavities of discrete molds, to individually regulate the extent of biaxial stretching of parisons if the improved machine constitutes a stretch blow molding machine, and/or to otherwise individually select any and all parameters which influence th~ quality ::

~ 3 3 ~
of products and the output of the machine. For example, the controls of the machine can render it possible to individually select the temperature profiles for discrete molds 6 in order to take into account ~he nature oE
thermoplastic material of (different) parisons which are fed for delivery to certain molds. If the machine of the present invention is used for the making of bottles or like containers, it can turn out high-quality bottles the weight of which is less than the weight of similarly dimensioned bottles which are produced in conventional machines by between 5 and ~0 percent.
Each of the illustrated machines can be operated in such a way that the introduction of a parison 22 into an empty mold 6 takes place immediately upon completed removal of a freshly formed article 9 or 61.
This is possible regardless of whether the machine employs stationary molds or a set of molds which orbit about the parison distributing station. When the molds are caused to orbit, the just described mode oE inserting parisons 22 and of removing articles 9 or 61 reduces the necessary number of interruptions of orbital movement of the molds because each interruption can be used for insertion oE at least one parison as well as for removal of at least one article~ A reduction of the number of interruptions of orbital movement of the molds contributes to smoother operation of the machine, to a higher output of the machine and to greater predictability of the converting step because the parisons in the cavities of the molds need not be accelerated and decelerated as often as in presently 2 ~ 3 known machines with orbiting molds.
The placing of the parison distributing station 2 or 63 at or close to the center of the array of stationary or orbiting molds 6 also exhibits a number of important advantages. Thus, when the parisons are supplied in accordance with heretoEore known proposals, the station to which fresh parisons are delivered to -~
assume a position close to the molds is located outside of the annulus of orbiting molds. Therefore, it is invariably necessary to slow down or to actually arrest the mold which is about to receive a parison, and the same holds true for removal of finished articles from the cavities of molds in conventional machines. Repeated acceleration and deceleration of molds necessitates the provision of numerous controls and entails considerable wear upon the moving parts. Moreover, and as already pointed out above, conventional machines are -~
not suited for simultaneous production of two or more ;~
different types of blow molded articles because this would even further complicate the controls and the regulation of supply of electrical energy, heating liquid, coolant and pressurized gaseous fluido The machines which are shown in FIGS. 1 and 3 to 7 exhibit the additional advantage that the mass of moving parts (such as of the devices 10, 15 of FIG. 1, the lever 52 of FIG. 3 and the chute 33 of FIG. 7) is a minute fraction of the combined mass of molds and their rotary support. This reduces the energy requirements of the means for moving such parts and renders it possible to move the parts at a speed which is much higher than -~ ~3~2~
that of a turntable with a large number of molcs thereon9 Moreover, the intervals which are requ.ired for j, acceleration or dec01eration of a transferring and/or removing device are much shorter than those which elapse for acceleration or deceleration of a large number of molds which are mounted on a rotary support.

Claims

1. A method of making thermoplastic blow molded objects, comprising the steps of feeding parisons to a distributing station from a location outside of said distributing station; transferring parisons from said station to a plurality of blow molds around the distributing station; converting parisons in the respective molds into blow molded articles; and removing the articles from the respective molds.

2. The method of claim 1, wherein the step of removing an article from a mold immediately precedes the step of transferring a parison into the respective mold.

3. The method of claim 1, wherein each step of converting a parison in one of two selected molds takes place simultaneously with the step of transferring a parison into the other of the two molds and vice versa.

4. The method of claim 1, wherein said transferring step includes conveying the parisons along an arcuate path prior to introduction of parisons into molds.

5. The method of claim 4, wherein said arcuate path is an annular path and said removing step includes transporting articles from the respective molds toward the center of said annular path.

6. The method of claim 4, wherein said arcuate path is an annular path and said removing step includes transporting articles in directions away from the center of the annular path.

7. The method of claim 1, wherein the molds form a circle around the distributing station and said transferring step in-cludes clamping the parisons at the distributing station and delivering clamped parisons to the molds in the circle.

8. The method of claim 1, wherein said removing step includes lifting the articles out of the respective molds.

9. The method of claim 1, further comprising the step of holding the molds against movement relative to the distributing station in the course of said feeding, transferring, converting and removing steps, the step of transferring a parison into one of the molds taking place simultaneously with conversion of a parison into an article in another of the molds.

10. The method of claim 9, wherein said transferring and removing steps include continuously moving at least one conveyor between the distributing station and the molds and providing the at least one conveyor with facilities for accepting parisons at said station and for inserting accepted parisons into molds, and with facilities for accepting articles from molds.

11. The method of claim 10, wherein said transferring step includes delivering parisons from said station to the molds in a predetermined sequence and said removing step includes evacuating articles from molds in a predetermined sequence.

12. The method of claim 1, wherein said transferring step involves the use of mobile tongs for discrete parisons.

13. The method of claim 1, wherein said removing step includes lifting articles out of the respective molds and delivering the lifted articles to an article storing and evacuating facility.

14. The method of claim 1, wherein said transferring step includes simultaneously withdrawing a plurality of parisons from the distributing station.

15. The method of claim 1, wherein said removing step includes simultaneously removing articles from at least two molds.

16. The method of claim 1, wherein said transferring step includes pneumatically conveying parisons from said station to the molds.

17. The method of claim 1, wherein said removing step includes pneumatically conveying articles from the molds.

18. The method of claim 1, wherein said transferring step includes conveying parisons by gravity feed.

19. The method of claim 1, wherein said removing step includes evacuating articles by gravity feed.

20. The method of claim 1, wherein said transferring step includes conveying parisons with a pressurized fluid

21. The method of claim 1, wherein said removing step includes evacuating articles with a pressurized fluid.

22. Machine for making thermoplastic blow molded objects, particularly stretch blow molded objects, comprising a distributing station; means for feeding parisons to said station from outside of said station; a plurality of blow molds around said station; means for transferring parisons from said station into said molds for conversion into blow molded articles; and means for removing the blow molded articles from said molds.

23. The machine of claim 22, further comprising a support for said molds.

24, The machine of claim 23, wherein said support is stationary and said transferring means is movable relative to said station and the molds on said support.

25. The machine of claim 23, further comprising means for moving said molds relative to said station.

26. The machine of claim 25, wherein said moving means defines for the molds a predetermined path, said transferring means including means for delivering parisons into molds in a first portion of said path and said removing means including means for evacuating articles from molds in a different second portion of said path.

27. The machine of claim 23, wherein said transferring means is stationary relative to said support.

28. The machine of claim 23, wherein said transferring means is movable relative to said support.

29. The machine of claim 22, wherein said transferring means includes tongs for parisons and means for moving said tongs between said station and said molds.

30. The machine of claim 22, wherein said transferring means includes tongs for a plurality of parisons.

31. The machine of claim 22, wherein said transferring means includes tongs for parisons and means for moving said tongs between said station and said molds at an at least substantially constant speed.

32. The machine of claim 22, wherein said transferring means comprises tongs for parisons and said removing means is provided on said transferring means.

33. The machine of claim 22, wherein said transferring means includes tongs for parisons and means for moving said tongs between said station where the tongs receive parisons and between said molds where the tongs are relieved of parisons, and further comprising means for controlling said moving means.

34. The machine of claim 33, wherein said transferring means comprises a lever having a plurality of arms and means for pivoting said lever about a predetermined axis which is disposed between said arms, said tongs being provided on one of said arms and said removing means being provided on another of said arms.

35. The machine of claim 34, wherein said controlling means comprises means circulating said axis along a substantially circular path about said station.

36. The machine of claim 34, wherein each of said arms includes a first portion which is pivotable about said axis and a second portion which is pivotable relative to the first portion, said tongs and said removing means being carried by the second portions of the respective arms.

37. The machine of claim 34, wherein said controlling means includes means for maintaining said removing means in register with an article-containing mold and for simultaneously maintaining said tongs in register with a parison at said station.

38. The machine of claim 37, wherein said molds are open-and-shut molds.

39. The machine of claim 22, wherein each of said molds is an open-and-shut mold having a plurality of sections defining a cavity for parisons and articles, at least one of said mold sections being movable relative to at least one other mold section between an open position in which a parison is insertable into or an article is removable from the cavity, and a closed position in which the parison or the article is confined in the cavity.

40. The machine of claim 39, further comprising means for moving said at least one section of at least two of said molds between open and closed positions and means for controlling the operation of said moving means.

41. The machine of claim 40, wherein said controlling means includes cam and cam follower means.

42. The machine of claim 41, wherein said controlling means further comprises means for moving said cam means relative to said molds.

43. The machine of claim 42, wherein said cam means includes at least one endless cam surrounding said station.

44. The machine of claim 40, wherein said controlling means includes a rotor and means for driving said rotor about an axis at said station.

45. The machine of claim 44, wherein said rotor includes an end wall, said controlling means further comprising cam means on said end wall and follower means tracking said cam means and operative to move said one section of each of said at least two molds relative to each other section of the respective mold in response to rotation of said rotor.

46. The machine of claim 45, wherein said rotor further comprises an annular wall and additional cam means provided on said annular wall, and further comprising means for converting parisons into articles, said converting means having additional follower means tracking said additional cam means.

47. The machine of claim 46, wherein the additional cam means on said annular wall includes at least one groove cam.

48. The machine of claim 46, wherein said converting means includes valves arranged to admit a pressurized gaseous fluid into parisons in the cavities of said molds, and means for actuating said valves, said actuating means receiving motion from said additional follower means.

49. The machine of claim 48, wherein said actuating means comprises holders for said valves and said holders being reciprocable relative to the parisons in the cavities of said molds in response to rotation of said rotor and resulting displacement of said additional follower means.

50. The machine of claim 49, wherein each of said holders includes means for sealing the parisons in their mold cavities to prevent the escape of gaseous fluid from parisons when said valves are open.

51. The machine of claim 46, wherein said converting means includes means for mechanically stretching parisons in the cavities of said molds, said stretching means receiving motion from said additional follower means.

52. The machine of claim 51, wherein said converting means further comprises step-up transmission means interposed between said stretching means and said additional follower means.

53. The machine of claim 52, wherein said transmission means comprises an input element receiving motion from said additional follower means, an output element operatively connected with said stretching means, and an intermediate element receiving motion from said input element and arranged to transmit motion to said output element so that the extent of movement of said output element exceeds the extent of movement of said input element.

54. The machine of claim 53, wherein at least one of said elements of said transmission means includes a belt and pulley drive.

55. The machine of claim 53, wherein said intermediate element includes a belt and pulley drive having a larger-diameter pulley driven by said input element, a smaller-diameter pulley arranged to drive said output element, and an endless flexible element trained over said pulleys.

56. The machine of claim 53, wherein said transmission means further comprises a friction-operated coupling between said additional follower means and said input element.

57. The machine of claim 48, further comprising a friction-operated coupling between said additional follower means and said converting means.

58. The machine of claim 48, wherein the additional cam means on said annular wall includes a single lobe which is tracked by said additional follower means to effect an opening of said valves.

59. The machine of claim 58, wherein said lobe includes two flanks making with the remaining portion of the additional cam means on said annular wall angles of between 100 and 150 degrees.

60. The machine of claim 59, wherein at least one of said angles is at least close to 135 degrees.

61. The machine of claim 48, wherein said additional cam means on said annular wall includes a first cam and a second cam, said additional follower means including a first follower tracking said first cam and a second follower tracking said second cam, said end wall being substantially horizontal and said rotor being turnable about a substantially vertical axis, said first follower being operatively connected with said valves and said first cam being located at a level below said second cam, said converting means further comprising means for mechanically stretching pari-sons in the cavities of said molds and means, including said second follower, for moving said stretching means relative to said molds.

62. The machine of claim 61, wherein said second cam is an annular cam and includes a first section at a first level and a second section at a level other than said first level.

63. The machine of claim 62, wherein said first section is located at a level below said second section.

64. The machine of claim 62, wherein the length of said first section in the circumferential direction of said annular wall equals or approximates the length of said second section.

65. The machine of claim 62, wherein said second cam further includes gradual transitions between said first and second sections.

66. The machine of claim 65, wherein said transitions are inclined relative to said sections at angles of between 40 and 60 degrees.

67. The machine of claim 22, wherein said transferring means includes at least one chute for parisons.

68. The machine of claim 67, wherein said chute has a slope which is sufficient to ensure that a parison which enters the chute slides by gravity toward one of said molds.

69. The machine of claim 22, wherein said transferring means includes at least one trough and means for pneumatically conveying parisons in said trough from said station to a selected mold.

70. The machine of claim 22, wherein said transferring means includes a chute for each of said molds, each of said chutes having an upper end portion adjacent said station and a lower end portion adjacent the respective mold, said transferring means further comprising means for releasably locking the lower end portions of said chutes.

71. The machine of claim 22, wherein said molds form a ring around said station.

72. The machine of claim 71, wherein said station is located at or close to the center of said ring.