(19)
(11)EP 3 349 960 B1

(12)EUROPEAN PATENT SPECIFICATION

(45)Mention of the grant of the patent:
10.06.2020 Bulletin 2020/24

(21)Application number: 16770267.9

(22)Date of filing:  22.09.2016
(51)International Patent Classification (IPC): 
B29C 45/56(2006.01)
(86)International application number:
PCT/EP2016/072521
(87)International publication number:
WO 2017/050881 (30.03.2017 Gazette  2017/13)

(54)

INJECTION MOULDING METHOD

SPRITZGIESSVERFAHREN

PROCÉDÉ DE MOULAGE PAR INJECTION


(84)Designated Contracting States:
AL AT BE BG CH CY CZ DE DK EE ES FI FR GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR

(30)Priority: 25.09.2015 GB 201517010

(43)Date of publication of application:
25.07.2018 Bulletin 2018/30

(73)Proprietor: GR8 Engineering Limited
Chichester, West Sussex PO19 7JU (GB)

(72)Inventor:
  • CLARKE, Peter Reginald
    Petworth West Sussex GU28 0NU (GB)

(74)Representative: Jenkins, Peter David 
Page White & Farrer Bedford House John Street
London WC1N 2BF
London WC1N 2BF (GB)


(56)References cited: : 
EP-A2- 2 653 286
JP-A- 2014 237 226
US-A- 3 602 946
JP-A- S63 179 722
JP-B2- 2 870 341
  
      
    Note: Within nine months from the publication of the mention of the grant of the European patent, any person may give notice to the European Patent Office of opposition to the European patent granted. Notice of opposition shall be filed in a written reasoned statement. It shall not be deemed to have been filed until the opposition fee has been paid. (Art. 99(1) European Patent Convention).


    Description


    [0001] The present invention relates to a method of injection moulding an article. In particular, the present invention relates to the injection moulding of preforms for containers from thermoplastic resin material.

    [0002] Injection moulding of articles from plastics materials, in particular thermoplastic polymers, is well known in the art. In particular, the injection moulding of containers, and preforms for containers, from plastics material is conventional in the art.

    [0003] It is often desired to injection mould plastics containers having a small wall thickness, for example to reduce material costs. When it is necessary to injection mould an article, such as a container preform, having a high L/T ratio (where L is the flow length of the molten plastics material from the injection gate and T is the wall thickness), a high injection pressure at the gate is needed to ensure that the mould cavity is filled with the molten plastics material. The gate acts to restrict material flow therethrough, and the wall section directly opposite the gate also restricts the material flow into the cavity. However, for wall thicknesses of less than 1 mm and L/T ratios of greater than 50, even if a high injection pressure at the gate is used the periphery of the mould cavity most remote from the gate may not be fully filled with the molten plastics material. It has been proposed to flow the molten material into the cavity at a faster rate to try to fill the cavity, which may require to increase the fill pressure. The higher fill pressure will, in turn, require a higher mould clamp pressure to counter the hydraulic force on the walls defining the mould cavity. It should be readily apparent to the skilled reader why injection moulding machines for the manufacture of plastics packaging need to have very high injection speeds and pressures, and very rigid platens, with consequential complexity and expense, to make what appears to be a simple article or preform.

    [0004] JP-A-S63/179722 discloses molding a product by extruding a melt between a movable mold and a fixed mold after the melt is poured into a groove section formed in the center of the movable mold and then compressing the melt while the movable mold is actuated.

    [0005] There is a need in the art for a cost effective, robust injection moulding process that at least partly overcomes the various problems with known processes as discussed above.

    [0006] In particular, there is a need for an injection moulding process, that is suitable for producing injection moulded articles, such as containers, preforms for containers, lids, tubs, closures, etc. having high flow-length: wall thickness ratios, and/or low material stress, which can be produced using conventional injection moulding machines and therefore can be interfaced with the minimum of problems into conventional production practices.

    [0007] The present invention aims at least partly to meet these needs in the art of injection moulded article, in particular container preform, manufacture.

    [0008] The present invention accordingly provides a method of injection moulding an article according to claim 1.

    [0009] Optionally, step (e) of moving the second movable mould part is commenced after closing the injection inlet in step (d).

    [0010] Optionally, in steps (e) and (f) the first movable mould part and the second movable mould part are moved at least partly simultaneously, further optionally simultaneously.

    [0011] Optionally, step (e) to move the second movable mould part is commenced, and further optionally completed, before step (f) to move the first movable mould part.

    [0012] Optionally, step (f) to move the first movable mould part is carried out at least partly simultaneously, further optionally simultaneously, with step (g) to move the second movable mould part.

    [0013] Optionally, in step (g) the first movable mould part is stationary.

    [0014] Optionally, after step (e), and further optionally after steps (e) and (f), the first and second movable mould parts and the at least one further mould part are disposed in a second configuration so as to define a second intermediate moulding cavity at least partly filled with the moulding material.

    [0015] Optionally, the second intermediate moulding cavity has a larger moulding volume than the first intermediate moulding cavity.

    [0016] Preferred features are defined in the dependent claims.

    [0017] Accordingly, the preferred embodiments of the present invention provides a method which can actively changes the L/T ratio of a moulded article during injection from a relatively low average L/T ratio in a first intermediate moulding cavity to a relatively high average L/T ratio in a subsequent second intermediate moulding cavity, and a yet relatively higher average L/T ratio in a subsequent final moulding cavity. This is achieved by allowing first and second movable mould parts to move forwardly and/or rearwardly after during injection to effectively reduce the L/T ratio in a step-wise manner by defining three successive cavity configurations of progressively reducing L/T ratio.

    [0018] This invention in one particular embodiment employs a mould in an injection moulding machine in which the filling pressure of the injected material to be moulded is controlled by moving a part of the mould away from the injection gate, or vice versa. In either case, this movement of a mould part can increase the width of the portion of the mould cavity opposite the gate and so provide a low average L/T ratio during injection, and thereby reduce the filling pressure of the injected material. Thereafter the average L/T ratio is progressively increased in a step-wise manner to produce the final moulded article.

    [0019] The method can be used for injection moulding a variety of articles, typically having a large substantially flat structure, and in particular preferably composed of PET, such as preforms for containers, trays, closures, lids, tubs, etc, which can be circular but optionally having a non-circular or non-rounded, e.g. rectangular, configuration in plan.

    [0020] The lids may be thin lids that are moulded with a shape and configuration to fit any desired container.

    [0021] Embodiments of the present invention will now be described by way of example only with reference to the accompanying drawings, in which:

    Figure 1 is a schematic cross-section through an injection mould having movable parts for use in a method of injection moulding a preform in accordance with a first embodiment of the present invention;

    Figure 2 is a schematic cross-section through the injection mould of Figure 1 showing injection of a molten material into a first intermediate moulding cavity formed by a first arrangement of the movable mould parts in a first phase of the method;

    Figure 3 is a schematic cross-section through the injection mould of Figure 1 showing the molten material in the first intermediate moulding cavity after closure of the gate of the injection inlet;

    Figure 4 is a schematic cross-section through the injection mould of Figure 1 showing a second arrangement of the movable mould parts in a second phase of the method;

    Figure 5 is a schematic cross-section through the injection mould of Figure 1 showing a third arrangement of the movable mould parts in a third phase of the method; and

    Figure 6 and 7 respectively illustrate plan and cross-sectional views of the substantially planar preform produced according to the method using the injection mould of the illustrated embodiment of Figures 1 to 5.



    [0022] Referring to Figures 1 to 5, there is shown an injection mould 2 for use in a method in accordance with a first embodiment of the present invention for injection moulding a preform 100 for subsequent moulding to form a container. The preform 100 is substantially planar. The preform 100 is moulded from a thermoplastic resin material. Typically, the thermoplastic resin material comprises polyester, for example at least one polyalkylene polyester or a blend of polyalkylene polyesters. Preferably, the polyester comprises at least one polyester selected from polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate and polybutylene naphthalate. Most preferably the polyester comprises polyethylene terephthalate (PET).

    [0023] Although the embodiment shows a substantially planar preform 100, the invention can be used to mould other preform shapes, as stated above, and using other thermoplastic resins.

    [0024] The injection mould 2 comprises first and second movable mould parts 4, 6 and at least one further mould part 8. These mould parts 4, 6, 8 define a mould cavity 10 of the injection mould 2.

    [0025] The injection mould 2 further comprises an injection inlet 12 for injecting molten thermoplastic resin material into the mould cavity 10. The injection inlet 12 is located in the vicinity of the first movable mould part 4 and the second movable mould part 6 is remote from the injection inlet 12. The injection inlet 12 comprises a feed nozzle 14 and a gate 16 of the feed nozzle 14, the gate 16 being controllable in known manner selectively to open and close the injection inlet 12 by movement of a valve pin 17. The injection inlet 12 may be located in or opposite to the first movable mould part 4. In the illustrated embodiment, the injection inlet 12 is located in the first movable mould part 4. The injection inlet 12 preferably has a dynamic seal to allow the first mould part 4 to slide in a back and forth manner along the injection inlet 12, and the valve pin 17 at the 16 gate also moves with the reciprocating stroke.

    [0026] The first and second movable mould parts 4, 6 are on a common side of the injection mould 2. The at least one further mould part 8 is on an opposite side of the injection mould 2 from the first and second movable mould parts 4, 6. In the illustrated embodiment, a mould separation line 18 is provided between two mould halves 20, 22. A first mould half 20 comprises a first further mould part 24, which is stationary during the moulding process, and a second mould half 22 comprises the first and second movable mould parts 4, 6 and a second further mould part 26, which is stationary during the moulding process.

    [0027] The first and second movable mould parts 4, 6 are mutually adjacent. The second movable mould part 6 is annular and wholly surrounds the first movable mould part 4.

    [0028] The second movable mould part 6 moulds at least a part, or all, of an outer peripheral portion 102 of the preform 100. The second further mould part 26 moulds at least a part, or all, of a peripheral edge 104 of the preform 100.

    [0029] The mould 2 is closed prior to the moulding method cycle by urging together two mould halves 20, 22 under a desired applied load.

    [0030] In the moulding method, referring in particular to Figure 1 initially the first and second movable mould parts 4, 6 and the further mould parts 24, 26 are disposed in a first configuration so as to define a first intermediate moulding cavity 30. In the first configuration the first movable mould part 4 is in a first rearward position and the second movable mould part 6 is in a first forward position.

    [0031] The first intermediate moulding cavity 30 has substantially the same volume as the final moulding cavity. The area and stroke of the first mould part 4 create a volume of the first intermediate moulding cavity 30 which is substantially equal to the volume of the whole article to be moulded. Accordingly, the first intermediate moulding cavity 30 has a preselected volume so that a predetermined dose is injected, the predetermined dose being determined by the volume of the first intermediate moulding cavity 30 which in turn is set by the spacing of the back position of the first mould part 4. Such a predetermined dose therefore can eliminate the need to use shooting pots or other upstream predosing of the volume of polymeric resin material to be injected and compression moulded.

    [0032] The back position of the first mould part 4 is preferably adjustable, typically by a distance of +/- 100 to 200 microns. Accordingly, the predetermined dose is adjustable by adjusting the back stroke limit of the first movable mould part 4.

    [0033] The back position of the second mould part 6 is also preferably adjustable, typically by a distance of +/- 100 to 200 microns. The adjustable dimension can be employed to mould preforms with different thicknesses, for example with a thickness +/- 100 to 200 microns thicker or thinner than a nominal design thickness of the preform. The adjustable thickness can be employed to optimize the weight of the container.

    [0034] The first intermediate moulding cavity 30 is defined substantially between the first movable mould part 4 and the first further mould part 24 opposite thereto. A peripheral edge of the first intermediate moulding cavity 30 is defined by a side surface 32, which is a non-moulding surface, of the second movable mould part 6. A moulding surface 34 of the first movable mould part 4 is located spaced from an opposite moulding surface 36 of the first further mould part 24. A moulding surface 38 of the second movable mould part 6 is located adjacent to an opposite moulding surface 40 of the first further mould part 24, and so no portion of the first intermediate moulding cavity 30 is defined between the second movable mould part 6 and the first further mould part 24. The first intermediate moulding cavity 30 has a minimum width of at least 1 mm. Most preferably, the first intermediate moulding cavity 30 has a width at any location thereof within the range of from 0.5 to 10 mm, further optionally from 1 to 5 mm, still further optionally from 0.7 to 1.2 mm.

    [0035] Then, referring in particular to Figure 2, molten thermoplastic resin material 42 is injected into the first intermediate moulding cavity 30 through the injection inlet 12 to fill the first intermediate moulding cavity 30 with the molten material 42. Typically, the molten material 42 is injected at an injection pressure of from 3,000kPa to 60,000kPa.

    [0036] Preferably, a predosed amount of the molten material 42 is injected into the first intermediate moulding cavity 30, and the predosed amount is typically within +/- 1 wt% of a target weight of the molten material 42 to be injected into the first intermediate moulding cavity 30. The target weight corresponds to a weight of the preform 100. The weight of the thermoplastic resin material 42 injected into the first intermediate moulding cavity 30 is the same as the weight of the preform 100. The use of such a predosed amount can avoid the need for any upstream predosing, since the volume of the first intermediate moulding cavity 30 in front of the first mould part 4 substantially defines the desired volume of material to be injected and so would correspond to the volume of any predose.

    [0037] After the required weight of thermoplastic resin material 42 has been injected, which weight is limited by the volume in front of the first mould part, the injection inlet 12 is closed, in particular by closing the gate 16 using the valve pin 17, as shown in Figure 3.

    [0038] Thereafter, referring in particular to Figure 4, in the illustrate embodiment the first movable mould part 4 is moved forwardly from the first rearward position to a second forward position and the second movable mould part 6 is moved rearwardly from the first forward position to a second rearward position. Such movements dispose the first and second movable mould parts 4, 6 and the further mould parts 24, 26 in a second configuration so as to define a second intermediate moulding cavity 44 filled with the molten material 42.

    [0039] In the illustrated embodiment, movement of the first and second movable mould parts 4, 6 is commenced after closing the injection inlet 12 and the first and second movable mould parts 4, 6 are moved simultaneously. However, in alternative embodiments, the first and second movable mould parts 4, 6 may be moved only at least partly simultaneously, i.e. one part 4, 6 may move prior to or after movement of the other part 4, 6. In further alternative embodiments, the second movable mould part 6 may be moved initially without any movement of the first mould part 4, which remains stationary, or the movement of the second movable mould part 6 may be commenced and optionally completed before any movement of the first mould part 4. Also, in alternative embodiments, the first and/or second movable mould parts 4, 6 be moved after commencement of the injecting step and at least partly after the closing step, i.e. one or both parts 4, 6 may start movement before the injection inlet 12 has been closed, although there is movement of one or both parts 4, 6 after the injection inlet 12 has been closed.

    [0040] The second intermediate moulding cavity 44 has a larger moulding volume than the first intermediate moulding cavity 30. The second intermediate moulding cavity 44 has a larger moulding area, when viewed as a plan, than the first intermediate moulding cavity 30. Typically, the second intermediate moulding cavity 44 has a moulding area, when viewed as a plan, which is from 80 to 120%, optionally from 90 to 110%, further optionally from 95 to 105%, larger than the first intermediate moulding cavity 30.

    [0041] Therefore typically the first and second mould parts 4, 6 have a substantially similar respective area. Typically, the first and second mould parts 4, 6 have respective areas which are within +/- 20%, preferably +/- 10%, more preferably +/- 5% of each other.

    [0042] The second intermediate moulding cavity 44 comprises a first portion 46 between the first movable mould part 4 and the first further mould part 24 and a second portion 48 between the second movable mould part 6 and the first further mould part 24. In the illustrated embodiment, the second portion 48 annularly surrounds the first portion 46.

    [0043] The second portion 48 has a larger width than the first portion 46. The second portion 48 typically has a minimum width of at least 0.5 mm, optionally wherein the second portion has a width at any location thereof within the range of from 0.5 to 10 mm, further optionally from 0.5 to 5 mm, still further optionally from 0.7 to 1.2 mm. The first portion 46 typically has a maximum width of no more than 1 mm. The second intermediate moulding cavity 44 has a larger volume than the final moulding cavity.

    [0044] As the second movable mould part 6 is moved rearwardly, from the first forward position to the second rearward position, the molten material 42 flows over the moulding surface 38 of the second movable mould part 6, and correspondingly also over the opposite moulding surface 40 of the first further mould part 24 which has been exposed by the rearward withdrawal of the second movable mould part 6. As the second movable mould part 6 is moved rearwardly, a portion 50 of the molten material 42 flows outwardly away, in the illustrated embodiment annularly away, from the first movable mould part 4.

    [0045] Thereafter, referring in particular to Figure 5, the second movable mould part 6 is moved forwardly from the second rearward position to a third forward position. This movement disposes the first and second movable mould parts 4, 6 and the further mould parts 24, 26 in a third configuration so as to define a final moulding cavity 52 of the injection mould 2 filled with the molten material 42. The final moulding cavity 52 defines a cavity outer surface 54 which defines the outer shape 106 of the preform 100 to be moulded. The first movable mould part 4 is stationary while the second movable mould part 6 is moved forwardly. As the second movable mould part 6 is moved forwardly, the molten material 42 is caused to fill the final moulding cavity 52 and the molten material 42 flows outwardly, in the illustrated embodiment annularly, away from the first movable mould part 4.

    [0046] At the end of the forward movement of the second movable mould part 6, the molten material 42 is packed under compression, by a clamping force, in the final moulding cavity 52 to define the final preform shape and dimensions. This may be achieved in a holding phase, and shrinkage of the solidified material may be substantially accommodated by the holding phase.

    [0047] When the first mould part 4 is advanced to its forward limit, the excess material is distributed over the second mould part 6. When the second mould part 6 is advanced to its forward limit, the material cannot flow back over the first mould part 4 because the material over the first mould part 4 has substantially solidified, and therefore the material over the first mould part 4 is shrinking and the pressure is reducing. The clamping force requirement is equal to the area of only one mould part, i.e. the second mould part 6, and not both the first and second mould parts 4, 6. This multistage moulding process therefore significantly reduces, and in the embodiment can effectively halve, the clamp force requirement for the preform to accommodate shrinkage of the solidified material.

    [0048] After the molten material 42 has solidified within the final moulding cavity 52, the injection mould 2 is opened by separating the two mould halves 20, 22 along the mould separation line 18, and the preform 100 is removed from the injection mould 2 for subsequent moulding into a container.

    [0049] In the illustrated embodiment, the final moulding cavity 52 has a maximum width of no more than 1 mm at any location thereof, optionally within the range of from 0.3 to 1 mm, further optionally from 0.5 to 0.75 mm.

    [0050] Typically the sequential steps of injecting the resin into the first intermediate mould cavity 30, firstly moving the first and second mould parts 4, 6 to form the second intermediate mould cavity 44, and secondly moving the second mould part 6 to form the final mould cavity 52 are conducted within a period of less than 2 seconds, optionally less than 1 second, further optionally less than 0.5 seconds.

    [0051] Figures 6 and 7 show plan and sectional views of the substantially planar preform 100 according to the illustrated embodiment. The preform 100 typically has a wall thickness T of from 0.3 to 0.75 mm, optionally from 0.4 to 0.6 mm, further optionally about 0.5 mm, over at least a central portion of the preform. The preform 100 has a surface area A of from 500 to 50,000 mm2. The preform 100 has a maximum width W and a wall thickness T, and the ratio of width W: wall thickness T is from 100:1 to 350:1, optionally from 150:1 to 250:1, further optionally about 200:1. The preform 100 has an average bulk width W' and a bulk depth D', and the ratio of average bulk width W': bulk depth D', defining a bulk aspect ratio, is at least 5:1, optionally from 5:1 to 25:1. The preform 100 has a bulk depth D' which is at most 25 mm, optionally from 1 to 25 mm, further optionally from 2 to 20 mm.

    [0052] The substantially planar preform 100 has an overall general shape and configuration which is planar, although the preform 100 may have some localised three-dimensional shaping. Typically, a peripheral edge 108 of the preform 100 is in the form of a three-dimensionally moulded non-planar flange 110 and is configured to form an upper edge of the resultant container. The flange 110 may be configured to engage a lid, and may be pre-shaped with a lid-engaging or lid-sealing surface structure.

    [0053] In Figure 6 the solid rectangular line surrounds an area A moulded by the first mould part 4 and the area B surrounds the area A and is moulded by the second mould part 6. Typically area A and area B differ by no more than +/- 5%, preferably by no more than +/- 1%. The dotted line C indicates the peripheral edge of the material during moulding when the first and second mould parts 4, 6 are aligned.

    [0054] The preform 100 produced by the injection moulding method of the present invention may be made into a container by stretch moulding the preform 100, for example by thermoforming, optionally with plug assistance. In a particularly preferred embodiment the preform 100 is substantially planar and the resultant container is in the form of a tray.

    [0055] The movement of the first and second mould parts 4, 6 may be controlled by one or more pressure actuators (not shown), which may be pneumatically controlled, for example the pneumatic fluid being compressed air, or hydraulically controlled, for example using a hydraulic oil. The pressure actuator(s) can be selectively pressurised to urge the first and second mould parts 4, 6 to their respective forward positions. The forward and rearward positions can be defined by respective mechanical stops or by interlocking of the mould parts. The injection pressure from the injected molten resin material can urge the first movable mould part 4 rearwardly to the rearward position as shown in Figure 2. The rearward position can be defined by a mechanical stop. Typically, the pressure applied to the first mould part 4 is sufficient to force the material over the moulding surface of the second mould part 6, for example from 200 to 300 kilograms per square centimeter, and the the squeezing pressure to pack the moulding with the second mould part 6 is also for example from 200 to 300 kilograms per square centimeter.

    [0056] The method of the preferred embodiments of the present invention provide a method of injection compression moulding in which the moulding cavity receives a precise shot dose of resin material injected into it. With this method the shot dose is controlled by the volume in front of the first mould part. The forward strokes of the first and second mould parts are limited, and therefore do not apply continuous pressure to the material. A pressure is applied before shrinkage of the injected material, and after shrinkage of the injected material there is substantially no pressure applied to the material. The force required to advance the first mould part is only that needed to flow the material across the second mould part. The force required by the second mould part is what is needed to flow the material to the limit of the peripheral edge of the cavity, and subsequently the shrinkage allows the second mould part to reach its forward limit.

    [0057] The area and stroke of the first mould part create a volume equal to that of the whole moulded article to be produced, thereby creating a pre-determined dose that is adjustable by adjusting the back stroke limit, therefore eliminating the need to use shooting pots or other upstream pre-dosing.

    [0058] The back positions of the first and second mould parts are adjustable to create preforms with different thicknesses in the range of 100 to 200 microns thicker or thinner than the design thickness of the preform. This can optimize the weight of the resultant container.

    [0059] The projected area of the first and second mould parts are of a similar area. When the first mould part is advanced to its forward limit, the excess material is distributed over the second mould part. When the second mould part is advanced to its forward limit the material cannot flow back over the first mould part as the material over the first mould part has substantially solidified, therefore the material over the first mould part is shrinking and the pressure is reducing. The clamping force requirement is equal to the area of only one mould part, not both. This effectively halves the clamp force requirement for the preform.

    [0060] The thermoplastic resin is typically PET. The melt density of PET is approximately 1.2 gcm-3, the melt density is affected by the intrinsic viscosity (IV) and melt temperature of the PET. The density of solidified PET (at room temperature, for example 20°C) is approximately 1.33 gcm-3. Accordingly, there is approximately a 10% volume shrinkage of the PET within the mould cavity between the initial injected material and the final solidified material.

    [0061] In a particularly preferred embodiment, in order to accommodate the shrinkage of the solidified PET material, the volume of injected PET resin in front of the first mould part is adjusted to exactly 110% of that required to fill the final mould cavity to produce the moulded article. In another embodiment, using polypropylene (PP) the volume of injected PP resin would be 120% of that required to fill the final mould cavity to produce the moulded article, the higher % being due to the lower density of PP compared to PET.

    [0062] In the initial phase of the moulding operation in which the molten resin is injected into the first intermediate moulding cavity 30, the second mould part 6 is disposed forwardly to a first, initial, forward position.

    [0063] The second mould part 6 is then retracted to form the second intermediate moulding cavity 44, and the first mould part 4 is urged forward as the second mould part 6 is retracted so that resin material flows outwardly into the periphery of the second intermediate moulding cavity 44.

    [0064] The second mould part 6 then completes the filling of the second intermediate moulding cavity 44 by being moved forwardly to reach an intermediate forward position.

    [0065] After a subsequent dwell period during which the resin shrinkage is substantially completed, the second mould part 6 is moved forwardly to reach a second, final, forward limit and then there is no further pressure applied to the material by the second mould part 6.

    [0066] The second mould part 6 has two forward limits: the first, initial, forward limit almost touches the opposite moulding surface to minimize the thickness of the cavity at that location to prevent material flow over the front face of the second mould part 6 and therefore limit the moulding cavity volume to that which is defined in front of the first mould part 4; and a second, final, forward limit which defines the final thickness of the preform.

    [0067] During a cooling phase after solidification of the molten material, the pressure actuator(s) can be deactivated.

    [0068] Although various embodiments of the present invention have been described in detail, it will be apparent to those skilled in the art that other modifications of the injection mould and the injection moulding process may be employed that are within the scope of the invention as defined in the appended claims.


    Claims

    1. A method of injection moulding an article (100), the method comprising the steps of:

    (a) providing an injection mould (2) comprising a plurality of mould parts (4, 6, 8, 24, 26) defining a mould cavity (10) of the injection mould (2), the plurality of mould parts including first and second movable mould parts (4, 6), wherein the second movable mould part (6) is annular and wholly surrounds the first movable mould part (4), and the plurality of mould parts further includes at least one further mould part (8) which is on an opposite side of the injection mould (2) from the first and second movable mould parts (4, 6), the injection mould (2) further comprising an injection inlet (12) for injecting molten thermoplastic resin material into the mould cavity (10), wherein the injection inlet (12) is located in the vicinity of the first movable mould part (4) and the second movable mould part (6) is remote from the injection inlet (12);

    (b) disposing the first and second movable mould parts (4, 6) in a first configuration so as to define a first intermediate moulding cavity (30), in which first configuration the first movable mould part (4) is in a first rearward position and the second movable mould part (6) is in a first forward position, wherein in the first configuration the first intermediate moulding cavity (30) is defined substantially between the first movable mould part (4) and the at least one further mould part (8), a moulding surface (34) of the first movable mould part (4) is located spaced from an opposite moulding surface (36) of the at least one further mould part (8), and a moulding surface of the second movable mould part (6) is located adjacent to the opposite moulding surface (36) of the at least one further mould part (8);

    (c) injecting molten thermoplastic resin material (42) into the first intermediate moulding cavity (30) through the injection inlet (12) to fill the first intermediate moulding cavity (12) with the molten material (42);

    (d) closing the injection inlet (12);

    (e) after commencement of the injecting step and at least partly after the closing step, moving the second movable mould part (6) from the first forward position to a second rearward position;

    (f) moving the first movable mould part (4) from the first rearward position to a second forward position; and

    (g) moving the second movable mould part (6) from the second rearward position to a third forward position thereby to dispose the first and second movable mould parts (4, 6) in a final configuration so as to define a final moulding cavity (52) of the injection mould (2) filled with the molten material (42), the final moulding cavity (52) defining a cavity outer surface (54) which defines the outer shape (106) of the article (100) to be moulded.


     
    2. A method according to claim 1 wherein (i) the injection inlet (12) is located in or opposite to the first movable mould part (4) and/or (ii) the first and second movable mould parts (4, 6) are on a common side of the injection mould (2) and/or (iii) wherein the first and second movable mould parts (4, 6) are mutually adjacent.
     
    3. A method according to claim 1 or claim 2 wherein the second movable mould part (6) moulds at least a part, or all, of an outer peripheral portion (102) of the article (100).
     
    4. A method according to any foregoing claim wherein the first intermediate moulding cavity (30) has substantially the same volume as the final moulding cavity (52).
     
    5. A method according to any foregoing claim wherein in injection step (c) a predosed amount of the molten material (42) is injected into the first intermediate moulding cavity (30), optionally wherein in injection step (c) the predosed amount of the molten material (42) is within +/- 1 wt% of a target weight of the molten material (42) to be injected into the first intermediate moulding cavity (30).
     
    6. A method according to any foregoing claim wherein step (e) of moving the second movable mould part (6) is commenced after closing the injection inlet (12) in step (d) and wherein either in steps (e) and (f) the first movable mould part (4) and the second movable mould part (6) are moved at least partly simultaneously, optionally simultaneously, or step (e) to move the second movable mould part (6) is commenced, and optionally completed, before step (f) to move the first movable mould part (4).
     
    7. A method according to any foregoing claim wherein either step (f) to move the first movable mould part (4) is carried out at least partly simultaneously, optionally simultaneously, with step (g) to move the second movable mould part (6), or in step (g) the first movable mould part (4) is stationary.
     
    8. A method according to any foregoing claim wherein after step (e), and optionally after steps (e) and (f), the first and second movable mould parts (4, 6) and the at least one further mould part (24) are disposed in a second configuration so as to define a second intermediate moulding cavity (44) at least partly filled with the molten material (42), optionally (i) wherein the second intermediate moulding cavity (44) has a larger moulding volume than the first intermediate moulding cavity (30) and/or (ii) wherein the second intermediate moulding cavity (44) has a larger moulding area, when viewed as a plan, than the first intermediate moulding cavity (30), optionally wherein the second intermediate moulding cavity (44) has a moulding area, when viewed as a plan, which is from 80 to 120%, optionally from 90 to 110%, further optionally from 95 to 105%, larger than the first intermediate moulding cavity (30).
     
    9. A method according to claim 8 wherein (i) the second intermediate moulding cavity (44) comprises a first portion (46) between the first movable mould part (4) and at least one further mould part (24) and a second portion (48) between the second movable mould part (6) and the at least one further mould part (24), and the second portion (48) has a larger width than the first portion (46), optionally wherein the second portion (48) annularly surrounds the first portion (46), and/or (ii) the second intermediate moulding cavity (44) has a larger volume than the final moulding cavity (52).
     
    10. A method according to claim 9 wherein (i) the second portion (46) has a minimum width of at least 0.5 mm, optionally wherein the second portion (46) has a width at any location thereof within the range of from 0.5 to 10 mm, further optionally from 1 to 5 mm, still further optionally from 0.7 to 1.2 mm, and/or (ii) the first portion has a maximum width of no more than 1 mm, optionally from 0.3 to 1 mm.
     
    11. A method according to any foregoing claim wherein in step (e) as the second movable mould part (6) is moved from the first forward position to the second rearward position the molten material (42) flows over a moulding surface (38) of the second movable mould part (6), and optionally a portion of the molten material (42) flows outwardly away from the first movable mould part (4), further optionally a portion of the molten material (42) flows annularly away from the first movable mould part (4).
     
    12. A method according to any foregoing claim wherein in step (g) as the second movable mould part (6) is moved from the second rearward position to the third forward position the molten material (42) is caused to fill the final moulding cavity (52), and optionally the molten material (42) flows outwardly away from the first movable mould part (4), further optionally the molten material (42) flows annularly away from the first movable mould part (4).
     
    13. A method according to any foregoing claim wherein the final moulding cavity (52) has a maximum width of no more than 1 mm at any location thereof, optionally within the range of from 0.3 to 1 mm, further optionally from 0.5 to 0.75 mm.
     
    14. A method according to any foregoing claim wherein the article (100) is a substantially planar preform for forming a container or a substantially planar lid for a container, optionally (i) wherein the article (100) has a wall thickness T of from 0.3 to 0.75 mm, optionally from 0.4 to 0.6 mm, further optionally about 0.5 mm, over at least a central portion of the article and/or (ii) wherein the article (100) has a surface area A of from 500 to 50,000 mm2.
     
    15. A method according to any foregoing claim wherein after steps (e) and (f), the first and second movable mould parts (4, 6) and the at least one further mould part (24) are disposed in a second configuration so as to define a second intermediate moulding cavity (44) at least partly filled with the molten material (42), and wherein the first intermediate moulding cavity (30) moulds a first intermediate article having a first L/T ratio, the second intermediate moulding cavity (44) moulds a second intermediate article having a second L/T ratio and the final moulding cavity (52) moulds a final article (100) having a third L/T ratio, wherein each L/T ratio is a ratio, averaged along a maximum length of the respective article, of the maximum length of the article and a thickness of the article along that maximum length, and wherein the first L/T ratio is lower than the second L/T ratio and the second L/T ratio is lower than the third L/T ratio.
     


    Ansprüche

    1. Ein Verfahren zum Spritzgießen eines Gegenstandes (100), wobei das Verfahren die Schritte aufweist:

    (a) Bereitstellen einer Spritzgussform (2) mit mehreren Formteilen (4, 6, 8, 24, 26), die einen Formhohlraum (10) der Spritzgussform (2) definieren, wobei die mehreren Formteile erste und zweite bewegbare Formteile (4, 6) aufweisen, wobei das zweite bewegbare Formteil (6) ringförmig ist und das erste bewegbare Formteil (4) vollständig umgibt und die mehreren Formteile ferner wenigstens ein weiteres Formteil (8) enthalten, das sich auf einer dem ersten und zweiten bewegbaren Formteil (4, 6) gegenüberliegenden Seite der Spritzgussform (2) befindet, wobei die Spritzgussform (2) ferner einen Einspritzeinlass (12) zum Einspritzen von geschmolzenem thermoplastischem Harzmaterial in den Formhohlraum (10) aufweist, wobei der Einspritzeinlass (12) in der Nähe des ersten bewegbaren Formteils (4) angeordnet ist und das zweite bewegbare Formteil (6) vom Einspritzeinlass (12) entfernt ist;

    (b) Anordnen des ersten und des zweiten bewegbaren Formteils (4, 6) in einer ersten Konfiguration, um einen ersten Zwischenformhohlraum (30) zu definieren, in welcher ersten Konfiguration sich das erste bewegbare Formteil (4) in einer ersten hinteren Position befindet und sich das zweite bewegbare Formteil (6) in einer ersten vorderen Position befindet, wobei in der ersten Konfiguration der erste Zwischenformhohlraum (30) im Wesentlichen zwischen dem ersten bewegbaren Formteil (4) und dem wenigstens einen weiteren Formteil (8) definiert ist, eine Formfläche (34) des ersten bewegbaren Formteils (4) von einer gegenüberliegenden Formfläche (36) des wenigstens einen weiteren Formteils (8) beabstandet angeordnet ist und eine Formfläche des zweiten bewegbaren Formteils (6) angrenzend an die gegenüberliegenden Formfläche (36) des wenigstens einen weiteren Formteils (8) angeordnet ist;

    (c) Einspritzen von geschmolzenem thermoplastischem Harzmaterial (42) durch den Einspritzeinlass (12) in den ersten Zwischenformhohlraum (30), um den ersten Zwischenformhohlraum (12) mit dem geschmolzenen Material (42) zu füllen;

    (d) Schließen des Einspritzeinlasses (12);

    (e) nach Beginn des Einspritzschritts und zumindest teilweise nach dem Schließschritt, Bewegen des zweiten bewegbaren Formteils (6) von der ersten vorderen Position in eine zweite hintere Position;

    (f) Bewegen des ersten bewegbaren Formteils (4) von der ersten hinteren Position in eine zweite vordere Position; und

    (g) Bewegen des zweiten bewegbaren Formteils (6) von der zweiten hinteren Position in eine dritte vordere Position, um dadurch das erste und das zweite bewegbare Formteil (4, 6) in einer Endkonfiguration anzuordnen, um so einen Endformhohlraum (52) der Spritzgussform (2) zu definieren, der mit dem geschmolzenen Material (42) gefüllt ist, wobei der Endformhohlraum (52) eine Hohlraumaußenfläche (54) definiert, die die äußere Form (106) des zu formenden Gegenstandes (100) definiert.


     
    2. Verfahren nach Anspruch 1, bei welchem (i) der Einspritzeinlass (12) in oder gegenüber dem ersten bewegbaren Formteil (4) angeordnet ist und/oder (ii) das erste und das zweite bewegbare Formteil (4, 6) auf einer gemeinsamen Seite der Spritzgussform (2) sind und/oder (iii) das erste und das zweite bewegbare Formteil (4, 6) aneinander angrenzen.
     
    3. Verfahren nach Anspruch 1 oder Anspruch 2, bei welchem das zweite bewegbare Formteil (6) zumindest einen Teil oder die Gesamtheit eines äußeren Umfangsabschnitts (102) des Gegenstandes (100) formt.
     
    4. Verfahren nach einem der vorhergehenden Ansprüche, bei welchem der erste Zwischenformhohlraum (30) im Wesentlichen das gleiche Volumen wie der Endformhohlraum (52) hat.
     
    5. Verfahren nach einem der vorhergehenden Ansprüche, bei welchem im Einspritzschritt (c) eine vordosierte Menge des geschmolzenen Materials (42) in den ersten Zwischenformhohlraum (30) eingespritzt wird, wobei optional im Einspritzschritt (c) die vordosierte Menge des geschmolzenen Materials (42) innerhalb +/- 1 Gew.-% eines Zielgewichts des geschmolzenen Materials (42) liegt, das in den ersten Zwischenformhohlraum (30) eingespritzt werden soll.
     
    6. Verfahren nach einem der vorhergehenden Ansprüche, bei welchem der Schritt (e) des Bewegens des zweiten bewegbaren Formteils (6) nach dem Schließen des Einspritzeinlasses (12) in Schritt (d) begonnen wird und entweder in den Schritten (e) und (f) das erste bewegbare Formteil (4) und das zweite bewegbare Formteil (6) zumindest teilweise gleichzeitig, optional gleichzeitig, bewegt werden oder der Schritt (e) zum Bewegen des zweiten bewegbaren Formteils (6) vor dem Schritt (f) zum Bewegen des ersten bewegbaren Formteils (4) begonnen und optional abgeschlossen wird.
     
    7. Verfahren nach einem vorhergehenden Ansprüche, bei welchem entweder Schritt (f) zum Bewegen des ersten bewegbaren Formteils (4) zumindest teilweise gleichzeitig, optional gleichzeitig mit Schritt (g) zum Bewegen des zweiten bewegbaren Formteils (6) ausgeführt wird, oder in Schritt (g) das erste bewegbare Formteil (4) stationär ist.
     
    8. Verfahren nach einem der vorhergehenden Ansprüche, bei welchem nach Schritt (e) und optional nach Schritten (e) und (f) das erste und zweite bewegbare Formteil (4, 6) und das wenigstens eine weitere Formteil (24) in einer zweiten Konfiguration angeordnet werden, um einen zweiten Zwischenformhohlraum (44) zu definieren, der zumindest teilweise mit dem geschmolzenen Material (42) gefüllt ist, wobei optional (i) der zweite Zwischenformhohlraum (44) ein größeres Formvolumen als der erste Zwischenformhohlraum (30) hat und/oder (ii) der zweite Zwischenformhohlraum (44) im Grundriss eine größere Formfläche als der erste Zwischenformhohlraum (30) hat, wobei optional der zweite Zwischenformhohlraum (44) im Grundriss eine Formfläche hat, die 80 bis 120%, optional 90 bis 110%, weiter optional 95 bis 105% größer als der erste Zwischenformhohlraum (30) ist.
     
    9. Verfahren nach Anspruch 8, bei welchem (i) der zweite Zwischenformhohlraum (44) einen ersten Abschnitt (46) zwischen dem ersten bewegbaren Formteil (4) und wenigstens einem weiteren Formteil (24) und einen zweiten Abschnitt (48) zwischen dem zweiten bewegbaren Formteil (6) und dem wenigstens einen weiteren Formteil (24) aufweist und der zweite Abschnitt (48) eine größere Breite als der erste Abschnitt (46) hat, wobei optional der zweite Abschnitt (48) den ersten Abschnitt (46) ringförmig umgibt, und/oder (ii) der zweite Zwischenformhohlraum (44) ein größeres Volumen als der Endformhohlraum (52) hat.
     
    10. Verfahren nach Anspruch 9, bei welchem (i) der zweite Abschnitt (46) eine minimale Breite von mindestens 0,5 mm hat, wobei optional der zweite Abschnitt (46) an jeder Stelle eine Breite im Bereich von 0,5 bis 10 mm, optionaler von 1 bis 5 mm, noch optionaler von 0,7 bis 1,2 mm hat, und/oder (ii) der erste Abschnitt eine maximale Breite von nicht mehr als 1 mm, optional von 0,3 bis 1 mm hat.
     
    11. Verfahren nach einem der vorhergehenden Ansprüche, bei welchem in Schritt (e), wenn das zweite bewegbare Formteil (6) von der ersten vorderen Position in die zweite hintere Position bewegt wird, das geschmolzene Material (42) über eine Formfläche (38) des zweiten bewegbaren Formteils (6) fließt und optional ein Teil des geschmolzenen Materials (42) von dem ersten bewegbaren Formteil (4) nach außen wegfließt, optionaler ein Teil des geschmolzenen Materials (42) ringförmig vom ersten bewegbaren Formteil (4) wegfließt.
     
    12. Verfahren nach einem der vorhergehenden Ansprüche, bei welchem in Schritt (g), wenn das zweite bewegbare Formteil (6) von der zweiten hinteren Position in die dritte vordere Position bewegt wird, das geschmolzene Material (42) zum Füllen des Endformhohlraums (52) veranlasst wird und optional das geschmolzene Material (42) von dem ersten bewegbaren Formteil (4) nach außen wegfließt, optionaler das geschmolzene Material (42) ringförmig von dem ersten bewegbaren Formteil (4) wegfließt.
     
    13. Verfahren nach einem der vorhergehenden Ansprüche, bei welchem der Endformhohlraum (52) an jeder Stelle eine maximale Breite von nicht mehr als 1 mm hat, optional im Bereich von 0,3 bis 1 mm, optionaler von 0,5 bis 0,75 mm.
     
    14. Verfahren nach einem der vorhergehenden Ansprüche, bei welchem der Gegenstand (100) ein im Wesentlichen planer Vorformling zum Bilden eines Behälters oder ein im Wesentlichen planer Deckel für einen Behälter ist, wobei optional (i) wobei der Gegenstand (100) eine Wandstärke T von 0,3 bis 0,75 mm, optional von 0,4 bis 0,6 mm, optionaler von etwa 0,5 mm, über zumindest einen zentralen Abschnitt des Gegenstandes hat und/oder (ii) der Gegenstand (100) eine Oberfläche A von 500 bis 50.000 mm2 hat.
     
    15. Verfahren nach einem der vorhergehenden Ansprüche, bei welchem nach den Schritten (e) und (f) das erste und das zweite bewegbare Formteil (4, 6) und das wenigstens eine weitere Formteil (24) in einer zweiten Konfiguration angeordnet werden, um einen zweiten Zwischenformhohlraum (44) zu definieren, der zumindest teilweise mit dem geschmolzenen Material (42) gefüllt ist, und der erste Zwischenformhohlraum (30) einen ersten Zwischengegenstand mit einem ersten L/T-Verhältnis formt, der zweite Zwischenformhohlraum (44) einen zweiten Zwischengegenstand mit einem zweiten L/T-Verhältnis formt und der Endformhohlraum (52) einen finalen Gegenstand (100) mit einem dritten L/T-Verhältnis formt, wobei jedes L/T-Verhältnis ein über eine maximalen Länge des jeweiligen Gegenstandes gemitteltes Verhältnis der maximalen Länge des Gegenstandes und einer Dicke des Gegenstandes entlang dieser maximalen Länge ist, und wobei das erste L/T-Verhältnis niedriger als das zweite L/T-Verhältnis ist und das zweite L/T-Verhältnis niedriger als das dritte L/T-Verhältnis ist.
     


    Revendications

    1. Procédé de moulage par injection d'un article (100), le procédé comprenant les étapes de :

    (a) fournir un moule d'injection (2) comprenant une pluralité de parties de moule (4, 6, 8, 24, 26) définissant une cavité de moule (10) du moule d'injection (2), la pluralité de parties de moule comprenant des première et deuxième parties de moule mobiles (4, 6), la deuxième partie de moule mobile (6) étant annulaire et entourant entièrement la première partie de moule mobile (4), et la pluralité de parties de moule comprenant en outre au moins une autre partie de moule (8) qui se trouve sur un côté du moule d'injection (2) opposé aux première et deuxième parties de moule mobiles (4, 6), le moule d'injection (2) comprenant en outre une entrée d'injection (12) pour injecter un matériau de résine thermoplastique fondu dans la cavité de moule (10), l'entrée d'injection (12) étant située à proximité de la première partie de moule mobile (4) et la deuxième partie de moule mobile (6) étant éloignée de l'entrée d'injection (12) ;

    (b) disposer les première et deuxième parties de moule mobiles (4, 6) dans une première configuration de manière à définir une première cavité de moulage intermédiaire (30), dans laquelle première configuration, la première partie de moule mobile (4) est dans une première position reculée et la deuxième partie de moule mobile (6) est dans une première position avancée, dans laquelle première configuration, la première cavité de moulage intermédiaire (30) est essentiellement définie entre la première partie de moule mobile (4) et ladite au moins une autre partie de moule (8), une surface de moulage (34) de la première partie de moule mobile (4) étant située à distance d'une surface de moulage opposée (36) de ladite au moins une autre partie de moule (8), et une surface de moulage de la deuxième partie de moule mobile (6) étant située de manière adjacente à la surface de moulage opposée (36) de ladite au moins une autre partie de moule (8) ;

    (c) injecter un matériau de résine thermoplastique fondu (42) dans la première cavité de moulage intermédiaire (30) à travers l'entrée d'injection (12) pour remplir la première cavité de moulage intermédiaire (30) avec le matériau fondu (42) ;

    (d) fermer l'entrée d'injection (12) ;

    (e) après le commencement de l'étape d'injection et au moins en partie après l'étape de fermeture, déplacer la deuxième partie de moule mobile (6) de la première position avancée vers une deuxième position reculée ;

    (f) déplacer la première partie de moule mobile (4) de la première position reculée vers une deuxième position avancée ; et

    (g) déplacer la deuxième partie de moule mobile (6) de la deuxième position reculée vers une troisième position avancée pour ainsi disposer les première et deuxième parties de moule mobiles (4, 6) dans une configuration finale de manière à définir une cavité de moulage finale (52) du moule d'injection (2) remplie du matériau fondu (42), la cavité de moulage finale (52) définissant une surface extérieure de cavité (54) qui détermine la forme extérieure (106) de l'article (100) devant être moulé.


     
    2. Procédé selon la revendication 1, dans lequel (i) l'entrée d'injection (12) est située dans ou en face de la première partie de moule mobile (4), et/ou dans lequel (ii) les première et deuxième parties de moule mobiles (4, 6) sont sur un côté commun du moule d'injection (2), et/ou dans lequel (iii) les première et deuxième parties de moule mobiles (4, 6) sont mutuellement adjacentes.
     
    3. Procédé selon la revendication 1 ou 2, dans lequel la deuxième partie de moule mobile (6) moule au moins une partie ou la totalité d'une portion périphérique extérieure (102) de l'article (100).
     
    4. Procédé selon l'une quelconque des revendications précédentes, dans lequel la première cavité de moulage intermédiaire (30) a essentiellement le même volume que la cavité de moulage finale (52).
     
    5. Procédé selon l'une quelconque des revendications précédentes, dans lequel, à l'étape d'injection (c), une quantité pré-dosée du matériau fondu (42) est injectée dans la première cavité de moulage intermédiaire (30), éventuellement dans lequel, à l'étape d'injection (c), la quantité pré-dosée du matériau fondu (42) est dans la plage de +/- 1 % en poids d'un poids cible du matériau fondu (42) devant être injecté dans la première cavité de moulage intermédiaire (30).
     
    6. Procédé selon l'une quelconque des revendications précédentes, dans lequel l'étape (e) de déplacement de la deuxième partie de moule mobile (6) est commencée après la fermeture de l'entrée d'injection (12) à l'étape (d), et dans lequel soit, dans les étapes (e) et (f), la première partie de moule mobile (4) et la deuxième partie de moule mobile (6) sont déplacées au moins en partie de manière simultanée, éventuellement de manière simultanée, soit l'étape (e) de déplacement de la deuxième partie de moule mobile (6) est commencée, et éventuellement terminée, avant l'étape (f) de déplacement de la première partie de moule mobile (4).
     
    7. Procédé selon l'une des revendications précédentes, dans lequel soit l'étape (f) de déplacement de la première partie de moule mobile (4) est effectuée au moins en partie de manière simultanée, éventuellement de manière simultanée, avec l'étape (g) de déplacement de la deuxième partie de moule mobile (6), soit la première partie de moule mobile (4) est stationnaire à l'étape (g).
     
    8. Procédé selon l'une quelconque des revendications précédentes, dans lequel, après l'étape (e), et éventuellement après les étapes (e) et (f), les première et deuxième parties de moule mobiles (4, 6) et ladite au moins une autre partie de moule (24) sont disposées dans une deuxième configuration de manière à définir une deuxième cavité de moulage intermédiaire (44) au moins en partie remplie du matériau fondu (42), éventuellement (i) dans lequel la deuxième cavité de moulage intermédiaire (44) a un volume de moulage plus grand que la première cavité de moulage intermédiaire (30), et/ou (ii) dans lequel la deuxième cavité de moulage intermédiaire (44) a une zone de moulage plus grande, quand elle est vue comme un plan, que la première cavité de moulage intermédiaire (30), éventuellement dans lequel la deuxième cavité de moulage intermédiaire (44) a une zone de moulage, quand elle est vue comme un plan, qui est de 80 à 120 %, éventuellement de 90 à 110 %, voire même éventuellement de 95 à 105 %, plus grande que la première cavité de moulage intermédiaire (30).
     
    9. Procédé selon la revendication 8, dans lequel (i) la deuxième cavité de moulage intermédiaire (44) comprend une première portion (46) entre la première partie de moule mobile (4) et au moins une autre partie de moule (24), et comprend une deuxième portion (48) entre la deuxième partie de moule mobile (6) et ladite au moins une autre partie de moule (24), la deuxième portion (48) ayant une largeur plus grande que la première portion (46), éventuellement dans lequel la deuxième portion (48) entoure la première portion (46) de manière annulaire, et/ou (ii) la deuxième cavité de moulage intermédiaire (44) a un volume plus grand que la cavité de moulage finale (52).
     
    10. Procédé selon la revendication 9, dans lequel (i) la deuxième portion (48) a une largeur minimale d'au moins 0,5 mm, éventuellement dans lequel la deuxième portion (48) a une largeur, quel que soit son emplacement, comprise entre 0,5 et 10 mm, voire même éventuellement entre 1 et 5 mm, voire encore même éventuellement entre 0,7 et 1,2 mm, et/ou dans lequel (ii) la première portion a une largeur maximum ne dépassant pas 1 mm, éventuellement comprise entre 0,3 et 1 mm.
     
    11. Procédé selon l'une quelconque des revendications précédentes, dans lequel, à l'étape (e) lorsque la deuxième partie de moule mobile (6) est déplacée de la première position avancée vers la deuxième position reculée, le matériau fondu (42) s'écoule sur une surface de moulage (38) de la deuxième partie de moule mobile (6), et éventuellement une portion du matériau fondu (42) s'écoule vers l'extérieur loin de la première partie de moule mobile (4), voire même éventuellement une portion du matériau fondu (42) s'écoule de manière annulaire loin de la première partie de moule mobile (4).
     
    12. Procédé selon l'une quelconque des revendications précédentes, dans lequel, à l'étape (g) lorsque la deuxième partie de moule mobile (6) est déplacée de la deuxième position reculée vers la troisième position avancée, le matériau fondu (42) est amené à remplir la cavité de moulage finale (52), et éventuellement le matériau fondu (42) s'écoule vers l'extérieur loin de la première partie de moule mobile (4), voire même éventuellement le matériau fondu (42) s'écoule de manière annulaire loin de la première partie de moule mobile (4).
     
    13. Procédé selon l'une quelconque des revendications précédentes, dans lequel la cavité de moulage finale (52) a une largeur maximale ne dépassant pas 1 mm quel que soit son emplacement, éventuellement comprise entre 0,3 et 1 mm, voire même éventuellement comprise entre 0,5 et 0,75 mm.
     
    14. Procédé selon l'une quelconque des revendications précédentes, dans lequel l'article (100) est une préforme essentiellement plane servant à former un récipient ou un couvercle essentiellement plan pour un récipient, éventuellement (i) dans lequel l'article (100) a une épaisseur de paroi T de 0,3 à 0,75 mm, éventuellement de 0,4 à 0,6 mm, voire même éventuellement d'environ 0,5 mm, sur au moins une portion centrale de l'article, et/ou (ii) dans lequel l'article (100) a une aire surfacique A de 500 à 50000 mm2.
     
    15. Procédé selon l'une quelconque des revendications précédentes, dans lequel, après les étapes (e) et (f), les première et deuxième parties de moule mobiles (4, 6) et ladite au moins une autre partie de moule (24) sont disposées dans une deuxième configuration de manière à définir une deuxième cavité de moulage intermédiaire (44) au moins en partie remplie du matériau fondu (42), et dans lequel la première cavité de moulage intermédiaire (30) moule un premier article intermédiaire ayant un premier ratio L/T, la deuxième cavité de moulage intermédiaire (44) moule un deuxième article intermédiaire ayant un deuxième ratio L/T et la cavité de moulage finale (52) moule un article final (100) ayant un troisième ratio L/T, chaque ratio L/T étant un rapport, moyenné le long d'une longueur maximale de l'article correspondant, de la longueur maximale de l'article par une épaisseur de l'article le long de cette longueur maximale, et le premier ratio L/T étant inférieur au deuxième ratio L/T et le deuxième ratio L/T étant inférieur au troisième ratio L/T.
     




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    Cited references

    REFERENCES CITED IN THE DESCRIPTION



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    Patent documents cited in the description