Perfected double-walled assembled preform, and procedure for making it

Abstract

An assembled preform (1) is provided for the making of a double-walled blown container, comprising an external preform (10) and an internal preform (11) arranged inside said external preform (10), and between said external preform (10) and said internal preform (11) is defined a volume (6), the volume (6) containing a determined gas, and characterized in that said internal preform (11) comprises locking means (18) for cooperating by locking interference with a surface of an internal region (3) of said external preform (10) when said second internal preform (11) it is inserted inside said external preform (10). The process for the making of said assembled preform is also disclosed.

Description

[0001] PERFECTED DOUBLE-WALLED ASSEMBLED PREFORM, AND PROCEDURE FOR MAKING IT

[0002] DESCRIPTION

[0003] The present invention refers to a double-walled preform for the making of double-walled containers following the blowing of said preform and, more precisely, to an assembled preform made of two concentric pre forms wherein an internal preform is inserted inside an external preform in a fixed manner one inside the other . The present invention also relates to the process for the making of the aforementioned double-walled preform .

[0004] The present invention is directed to all fields wherein a container for the containing of liquids requires adequate barrier protections as a double-walled container can provide , and in order to preserve the characteristic properties of the contained liquid product over the time .

[0005] State of the art

[0006] As is known, containers obtained by blowing PET preforms or similar material are intended to contain liquids in di f ferent products sectors : beverage , chemical , pharmaceutical , food, etc .

[0007] For determined uses and applications it is necessary to make blown PET containers or similar material and having a double wall feature . More precisely, the system of the two concentric preforms is used when it is necessary to improve and enhance certain features that cannot be obtained using a single preform . The constructive solution of the container equipped with a double wall is particularly suitable for containers intended to contain liquids which need adequate protection in order to preserve their characteristic properties by protecting the liquid from contacting with the air or with other environments that can alter the chemical composition thereof .

[0008] For example , typical is the case of a traditional container which, when it is partially emptied, it foresees the increase of the head space with an increased amount of air contacting the liquid as the product comes out of the container . One of these conditions occurs for beer kegs .

[0009] In fact , in traditional containers , the beer is dispensed by blowing CO2 inside thereof . As the beer is dispensed, the headspace becomes enriched with CO2 , altering the balance between the liquid phase and the gaseous phase of the beer contained in the keg .

[0010] In the constructive solution where a double-walled container is provided, for the making of the latter the blowing of two PET preforms or similar material is foreseen, wherein an internal preform is coaxially inserted inside an external preform .

[0011] According to this embodiment , it is possible to have two individual pre forms with di f ferent mechanical features according to the final use of the blown container and to the liquid to be contained therein .

[0012] For example , through the process of blowing two preforms , it is possible to obtain a blown double walled container where the external preform will have the function of mechanically protecting the internal container, while the internal preform which is destined to receive the liquid, will have all the features and treatments necessary to preserve the properties of the liquid contained therein ( for example , O2 barrier, CO2 barrier, UV barrier, etc . ) .

[0013] This constructive solution has the disadvantage related to the fact that for the production process of the double preform, the step of inserting the internal preform into the external preform is normally carried out upstream of the blowing line . This assembling operation is performed by sending the two separate preforms to an expensive automation system which is designed for inserting the two preforms one into the other, and for conveying the assembled preform to the subsequent blowing step for the making of the double walled container .

[0014] On the other hand, according to an alternative production process , the internal and external preforms are assembled after the production thereof . The disadvantage of this alternative constructive solution consists in the fact that the fixing of the assembly is carried out through an expensive welding system so as to prevent the two preforms from slipping of f during the handling thereof .

[0015] Therefore , the present invention aims to solve the aforementioned disadvantages by providing an improvement to an assembled double walled preform and the production process therefor, wherein the assembling of the two preforms ( internal and external ) in a permanent , simple , and ef fective manner is provided .

[0016] Thanks to the technical solution of the present invention, the blown double-walled container is thus obtained by blowing an already assembled preform which contains a first and a second preform coaxially inserted one into the other in a locked manner .

[0017] Therefore , the obj ect of the present invention is to provide two preforms having a geometry such as to allow a fixed and permanent assembl ing of one preform inside the other, in such a way as to guarantee that during the necessary handling both for the transporting of the preforms and for the processing up to the blowing thereof , the stability of the assembly be not compromised .

[0018] BRIEF DESCRIPTION OF THE INVENTION

[0019] The obj ect of the present invention is a process for the making of a double-walled assembled concentric preform which comprises a first internal preform which coaxially inserted internally in a second external preform, and wherein the two concentric preforms are mechanically assembled in an irreversible manner and so as to form a single indivisible body .

[0020] According to one aspect of the present invention, the two concentric preforms are irreversibly coupled and can be handled and processed as i f they were a single preform .

[0021] According to another aspect of the present invention, the two preforms are produced individually, with materials which can be homogeneous or inhomogeneous .

[0022] The obj ect of the present invention is also the assembled concentric a double-walled preform obtained by means of the aforementioned process .

[0023] Therefore , the present invention provides a process for the making of a double-walled preform, and an assembled preform thus obtained substantially according to the appended claims .

[0024] DETAILED DESCRIPTION OF THE INVENTION

[0025] A detailed description of two preferred embodiments of a double-walled preform and the related assembling process according to the present invention will now be provided, given by way of a non-limiting example , with reference to the accompanying figures , wherein :

[0026] Figure 1 illustrates a longitudinal sectional view of an assembled double-walled preform of the state of the art ;

[0027] Figure 2 is a partially sectional and detailed view of a portion of the assembled preform of Figure 1 ;

[0028] Figure 3 is a partial view and in longitudinal section of a part of an assembled preform of the state of the art ;

[0029] Fig . 4A is a longitudinal sectional view of a first embodiment of an inner preform which forms part of the assembled double-walled preform of the present invention;

[0030] Fig . 4B is a longitudinal sectional view of a second embodiment of an inner preform which forms part of the assembled double-walled preform of the present invention;

[0031] Fig . 5A is an elevational and perspective view o f an assembled preform of the present invention;

[0032] Figure 5B is a perspective view and in longitudinal section of the assembled preform of Figure 5A according to the present invention; and

[0033] Figure 6 is a perspective view and partially in longitudinal section of the neck region of a blown container obtained with the assembled preform of the present invention .

[0034] With reference now to figures 1 , 2 and 3 , an assembled double wall preform according to the state of the art is illustrated therein .

[0035] As can be seen in Figure 1 , an assembled preform 1 i s provided, and consisting of a first external preform 10 and a second internal preform 11 inserted into the first external preform 10 , both the external 10 and internal 11 preforms typically having a cylindrical profile .

[0036] The external preform 10 has a neck region 2 which comprises a substantially smooth internal surface 3 , and an external surface 4 which constitutes the thread 5 for coupling with a relative cap (not shown in the figures ) in the manner already known per se .

[0037] On the other hand, the internal preform 11 can be completely included / contained in the external preform 10 or overlap it for a short distance ( as illustrated in figures 1 and 2 ) .

[0038] Similarly to the external preform 10 , the internal preform 11 also has a neck region 12 which has an internal surface (normally cylindrical or slightly f rusto-conical shaped) , and an external surface which typically has two contacting regions 13 and 14 for interfacing on the surface 3 of the respective neck region 2 of the external preform 10 (better illustrated below) .

[0039] As can be seen in the figure , after the assembling of the external 10 and internal 11 preforms , a volume 6 is generated and de fined between the external preform 10 and the internal preform 11 , the arrangement being such that once the container is blown the volume 6 is capable of generating an internal volume of gas which is functional for the operation of said container (better illustrated below) .

[0040] With reference now to figure 2 , once the internal 11 and external 10 preforms have been assembled, the contacting region 13 on the external surface of the neck region 12 of the internal preform 11 interfaces with interference on the internal surface 3 of the neck 2 of the external preform 10 , and in such a manner to create one or more interference regions which allow the two preforms 10 and 11 to be mutually locked in a solid and permanent manner once assembled .

[0041] Similarly and as already illustrated in figure 1 , when the internal preform 11 is housed within the external preform 10 , the contacting region 14 at the external surface of the neck region 12 of the internal preform 11 interfaces with interference on the internal surface 3 of the neck 2 of the external preform 10 , creating an interference region which allows the preforms 10 and 11 to be mutually locked in a solid and permanent manner, one inside the other .

[0042] Furthermore , and as can be seen in Figure 2 , at least one pair of holes 15 are provided at the surface of the neck region 12 ( only one of which being shown in the figure ) . Once the two external 10 and internal 11 preforms have been assembled, the holes 15 are able to pneumatically communicate the internal volume 6 with the external environment in order to allow the gas flow inside / outside from / toward said internal volume 6 .

[0043] With reference now to figure 3 , the internal preform has protruding annular elements 18 arranged on the whole circumference of its external wall , the arrangement is such that once the two external 10 and internal 11 preforms have been assembled, the protruding annular elements 18 abut on the internal wall of the external preform 10 . This constructive solution makes it pos sible to have the blocked connection between the external preform 10 and the internal preform 11 more rigid .

[0044] Furthermore , and in order to allow a pneumatic communication between the holes 15 and the internal volume 6 and the external environment ( to allow the gas to flow from / toward said internal volume 6 during the use of the blown container ) , a series of longitudinal grooves 17 obtained at the internal wall of the external preform 10 at the contacting region of the annular elements 18 is provided .

[0045] With reference now to Figures 4A and 4B, two embodiments of the internal preform made according to the present invention are respectively illustrated in perspective from above .

[0046] For the sake of clarity, like parts will have like numbers and the detailed description thereof will be here omitted here since it has already been provided above .

[0047] With reference now to figure 4A, according to the first embodiment of the present invention, an internal preform 11 is provided which has a series of longitudinal grooves 15 obtained at the neck region 12 , the arrangement being such that once the internal preform 11 has been assembled inside the external preform 10 , the grooves 15 allow pneumatic communication of the internal volume 6 with the outside ( as previously described and better illustrated hereinafter ) .

[0048] Furthermore , the outer wall of the preform 11 has a protruding surface 18 along the whole perimeter of the outer wall . The protruding surface 18 has a plurality of longitudinal grooves 180 .

[0049] With reference now to figure 4B, an internal preform 11 according to a second embodiment of the present invention, is provided, the preform 11 having at least one hole 15 at the neck region 12 , the arrangement being such that once the internal preform 11 is assembled within the external preform 10 the hole 15 allows a pneumatic communication of the internal volume 6 with the outside ( as previously described and better illustrated hereinafter ) .

[0050] Furthermore , the outer wall of the preform 11 has a series of protruding longitudinal surface elements 18 arranged alternately along the whole perimeter of the outer wall . The arrangement of the protruding surface elements 18 is such as to create a series of separation grooves 180 between a first protruding surface element 18 and a second protruding surface element 18 adj acent to the first .

[0051] Furthermore , according to this alternative embodiment , one or more spacing regions 110 in the outer surface of the preform 11 are provided which do not have protruding elements 18 , and these spacing regions 110 are intercalated between two series of protruding elements 18 ( in the figure only one spacing region 110 is shown) .

[0052] With reference now to figures 5A and 5B, an assembled preform 1 according to the first embodiment of the present invention is illustrated .

[0053] For the sake of clarity, like parts will have like numbers and the detailed description thereof will be here omitted since already provided above .

[0054] As can be seen in the figures , an assembled preform according to the present invention is provided, which consists of a first external preform 10 housing inside thereof in a fixed manner a second internal preform 11 ( the latter being made according to the present invention and as previously illustrated) .

[0055] As is evident in figure 5B, once the preform of the present invention has been assembled, the series of protruding elements 18 allow the blocking by interference of the respective walls of the internal preform 11 in the external preform 10 . With this arrangement , the grooves 180 (not shown in the figure ) allow the pneumatic communication of the internal volume 6 between the two preforms and the external environment , passing in a circuit defined through the series of grooves 15 at the neck region 12 of the internal preform 11 .

[0056] It should be noted here that, according to the present invention, similarly to the first embodiment of the internal preform 11 ( as i llustrated previously in figure 4A) , also according to the second embodiment of the internal preform 11 ( as illustrated in figure 4B ) once the preform 1 has been assembled, the outer wall spacing regions 110 of the internal preform 11 being free from any protruding elements 18 , allow a pneumatic communication between the internal volume 6 defined between the two preforms and the outer environment , through the holes 15 at the region of neck 12 of the internal preform 11 .

[0057] With reference now to figure 6 , the neck region of a blown container obtained with the assembled preform of the present invention is illustrated therein in a perspective and partially longitudinal section, and wherein the preferential flow channel of the gas coming from the internal volume 6 towards the outside during the functioning / emptying of the blown container obtained with the preform of the present invention is indicated by the arrows .

[0058] For the sake of clarity, like parts will have like numbers and the detailed description thereof will be here omitted as already given above .

[0059] As can be seen in the figure , once the preform 1 has been assembled according to the previously described embodiments , the same is blown according to an industrial process already known in the state of the art , and with the aim of obtaining a double-walled blown container ( only the top region of the neck region of the container being shown in the figure ) .

[0060] The blown container thus obtained therefore has a first container obtained by blowing the first preform 10 and a second container arranged inside the first container and obtained by blowing the internal preform 11 , the second container being capable of containing a liquid ( the liquid being typically a carbonated drink or similar ) . The second container being typically collapsible within the first container . This arrangement provides for a volume defined by the space 6 existing between the external preform 10 and the internal preform 11 once they are blown simultaneously, the volume 6 enveloping the wall of the internal container which wall is collapsible and therefore the internal volume 6 is variable .

[0061] The neck of the container does not undergo plastic deformation during the forming step (blowing) of the preform 1 and, therefore , retains the original structure of the assembled preform .

[0062] According to the present invention, the coupling in the contacting regions 18 between the two preforms 10 and 11 is preferably selected with an interference value of almost 0 . 2 mm, but can be in the comprised in the range from 0 . 02 mm up to 0 . 5 mm depending on the applications and the volume of the double-walled container obtained after the blowing of the assembled preform .

[0063] Therefore , as illustrated in the figure and according to the present invention, the arrangement of the grooves 180 formed at the outer wall of the internal preform 11 , and the ports 15 at the neck region 12 of the internal preform 11 is such that a preferential circuit is created as illustrated with the arrows F, and wherein the gas contained in the internal volume 6 between the external container 10 and the internal container 11 can flow more easily and quickly during operation / emptying of the blown container ( that is , both during filling of the blown container, both during the emptying of the blown container, and during the container recycling operations ) .

[0064] The facilitated flow of the gas through the aforementioned grooves 180 and 15 makes it possible to guarantee the absence of overpressure inside the container which could compromise the safety of the operators .

[0065] A description of the process for the manufacturing of the assembled preform 1 will now be provided .

[0066] First , the external 10 and internal 11 preforms are formed separately, each by inj ection moulding into a respective mould with a material which is chosen according to the applications for which the double-walled container is intended, obtained following the blowing of the said preform 1 once assembled .

[0067] Subsequently, the internal preform 11 is inserted inside the external preform 10 by bringing the neck part 12 of the internal preform 11 close to the neck part 3 of the external preform 10 .

[0068] Then, the inner preform 11 is pushed inside the outer preform 10 forcing the coupling by interference at the coupling surfaces areas 18 of the internal preform 11 at the respective surface region of the external preform 10 and as previously illustrated in the figures .

[0069] In this condition, the preform 1 is irreversibly assembled and is ready to be delivered to the subsequent production blowing steps for obtaining a double-walled blown container, and according to a production process as already known in the state of the art .

[0070] Advantages

[0071] The present invention has a number of advantages .

[0072] A first advantage is given by the fact that transporting costs are halved since two separate preforms are not transported anymore , but only one preform inserted into each other .

[0073] A second advantage is given by the fact that the reduction in transporting costs allows a considerable expansion of the markets and a considerable expansion of the fields of use of the concentric preforms .

[0074] A third advantage is given by the fact that the present double-walled preform can be fed directly into the blower, eliminating the expensive automation system for the inserting of the two preforms one into the other .

[0075] A fourth advantage is given by the fact that anyone who owns a blow moulding machine will be able to use the present preform without resorting to the automatic system which, in addition of being expensive , makes the system more complex and lowers its reliability .

Claims

CLAIMS1. Assembled preform (1) for the making of a double walled blown container, comprising a first external preform(10) which comprises a neck part (2) which has an external region (4) which includes a threaded region (5) and an internal region (3) , and a second internal preform (11) arranged inside said first external preform (10) , said second internal preform (11) having a neck region (12) , and wherein between said first external preform (10) and said second internal preform (11) is defined a volume (6) , said volume (6) being provided to contain a determined gas, and wherein said second internal preform (11) comprises locking means (18) integrally obtained at the external surface of said second internal preform (11) and for cooperating by blocked interference with an internal surface (3) of said first external preform (10) when said second internal preform (11) is inserted into said first external preform (10) , characterized in that said locking means comprises a protruding surface (18) which is obtained at the proximity of said neck region (12) of said second internal preform(11) , and in that said protruding surface comprises a plurality of protruding elements (18) having a longitudinal shape and parallel arranged to the longitudinal axis of said second internal preform (11) and arranged along the perimeter of the external wall of said second internal preform (11) , the arrangement being such that between a first and a second protruding longitudinal element (18) a separating groove (180) is provided, and such that a plurality of longitudinal grooves (180) is provided for the separating of said plurality of protruding elements (18) one from each other.

2. Assembled preform (1) according to the preceding claim, wherein one or more spacing regions (110) are provided at said outer surface of said second inner preform (11) , said one or more spacing regions (110) being arranged between a first and a second plurality of protruding elements (18) .

3. Assembled preform (1) according to claim 1 or 2, wherein said locking interference between said protrudingsurface (18) of said second internal preform (11) and said surface region of said first external preform (10) is comprised in the range from 0.02 mm to 0.5 mm.

4. Assembled preform (1) according to the preceding claim, wherein said blocking interference is about 0.1 mm.

5. Assembled preform (1) according to any of the preceding claims, wherein a plurality of longitudinal grooves (15) is obtained at the edge part of said neck region (12) of said second internal preform (11) , the arrangement being such that said grooves (15) pneumatically communicate said internal volume (6) with the external environment.

6. Assembled preform (1) according to any of the preceding claims 1-4, wherein at least one or more holes (15) are provided at the edge part of said neck region (12) of said second internal preform (11) , the arrangement being such that said at least one or more holes (15) pneumatically communicate said internal volume (6) with the external environment .

7. Process for the making an assembled preform (1) according to the preceding claims 1-6, characterized by the fact that it includes the following steps :- Separate forming of said external preform (10) and said internal preform (11) by a separate injection moulding process for each preform;- Insertion of said internal preform (11) inside said external preform (10) until the neck part (12) of the second internal preform (11) abuts on the neck part (3) of the first external preform (10) ;- Biasing the internal preform (11) towards the inside of the external preform (10) forcing by interference the coupling through said locking means (18) on said internal region (3) of the neck part (2) of said external preform (10) ; and- Obtaining an assembled double walled preform (1) irreversibly blocked.

Images