Injection blow molding die and method

Abstract

The injection blow mould comprises a punch (1) having a blow opening (3) and an exhaust opening (4), a blow mould cavity (2) configured to receive therein the punch (1) with a hot and soft preform (30a) disposed thereon, and a cooling device associated with the blow mould cavity (2), the blow opening (3) being connected to a first conduit (6) communicating with a first pressurised gas source configured to supply pressurised gas through the blow opening (3) at an overpressure (OP) above a blow pressure (BP) suitable for blowing the preform (30a) into a container (30b), and the exhaust opening (4) being connected to a second conduit (7) connected to a pressure limiting device set at the blow pressure (BP). Gas in the container (30b) that exceeds the blow pressure (BP) is allowed to escape through the exhaust opening (4), thereby creating a cooling gas flow from the blow opening (3) to the exhaust opening.

Description

Technical Field

[0001] The present invention generally relates to injection blow molding dies and methods, and more particularly to dies and methods for injection molding a plastic preform and blow molding the preform into a container. The injection blow molding dies and methods are useful in container molding machines.

Background Art

[0002] In container molding machines, there is known a type comprising a preform molding unit configured to form a preform by injecting a molten plastic material into a preform molding die, and a container molding unit configured to form a container by blowing the preform into a blow molding die.

[0003] In this known type of container molding machine, the preform molding die includes a preform molding cavity having an inner surface defining an outer surface of the preform, which cooperates with a punch having an outer surface defining an inner surface of the preform. The injection blow molding die includes a blow molding cavity having an inner surface defining an outer surface of the container obtained by blowing the preform. The blow molding cavity is configured to receive a punch therein and a preform disposed on the punch in a hot and soft state.

[0004] The injection blow molding die includes a blow device configured to deliver pressurized gas into the interior of a heated and soft preform through one or more blow openings disposed within the punch when the punch carrying the preform is disposed inside the blow molding cavity to expand the preform until the expanded preform contacts the inner surface of the blow molding cavity to form the container, and a cooling device configured to cool the outer surface of the container associated with (or attendant to, associated to) the blow molding cavity and in contact with the inner surface of the blow molding cavity.

[0005] Different types of transfer devices are known for transferring a punch carrying heated soft preform from a preform molding cavity to a blow molding cavity.

[0006] WO2017093578A1 discloses an injection and blow molding die comprising one or more rows of molding cavities arranged on a base plate, each row of cavities having an alternate arrangement of n injection molding cavities and n+1 blow molding cavities, with blow molding cavities on opposite ends of the row, and one or more rows of punches arranged on a movable plate, each row of punches having 2n punches aligned with each other. The movable plate is actuated to move alternately to move the punches from the injection molding cavities to the blow molding cavities and vice versa.

[0007] The mold of WO2017093578A1 described above further includes a plurality of injection nozzles configured to inject molten plastic material into an injection molding cavity to form a preform on a punch located within the injection molding cavity, and a blowing device configured to supply compressed gas into the interior of the preform located on the punch within the blow molding cavity through a blow opening located within the punch to inflate the preform into the container. The injection molding cavity and the blow molding cavity are formed in separate individual injection blocks and individual blow blocks, respectively. The blow blocks are cooled by a cooling fluid circulating through cooling conduits located inside the blow blocks to cool the outer surface of the container that is in contact with the inner surface of the blow molding cavity.

[0008] In any case, in order to obtain enough clay to allow the formed container to be removed from the injection blow molding die without deformation, the temperature must be lower than the temperature of the blow molding die, and the time required for this temperature decrease slows down the production speed of the container forming machine.

[0009] For example, when an injection blow molding die is used that has a cooling system containing a cooling fluid circulating through cooling conduits within the blow molding cavity, the cooling system cools only the outer surface of the container that is in contact with the inner surface of the blow molding cavity, but does not cool the inner surface of the container. Therefore, a relatively long cooling time is still required before the container can be removed from the injection blow molding die without deformation.

[0010] DE2605967A1 discloses an injection blow molding die that is internally cooled by circulating mist supplied and removed through an internal duct within a blow mandrel, comprising a combination of features included in the preamble of claim 1 of this patent application.

[0011] US3944141 also discloses a similar type, but it further uses a pressure bag. [Overview of the Initiative] [Problems that the invention aims to solve]

[0012] However, in order to shorten the cooling time required before the finished container can be removed from the injection blow molding die, an injection blow molding die is needed that is equipped with means for cooling both the outer and inner surfaces of the container once it has expanded in the blow molding cavity. [Means for solving the problem]

[0013] According to a first aspect, the present invention contributes to satisfying the above need by providing an injection blow molding die comprising a punch having an outer surface defining the inner surface of a plastic preform, an injection molding cavity configured to receive the punch therein and having an inner surface defining the outer surface of the preform, and a blow molding cavity having an inner surface defining the outer surface of a container obtained by blowing the preform.

[0014] An injection molding cavity is configured to receive a punch therein, and an injection device is configured to inject molten plastic material into the injection molding cavity through one or more injection nozzles when the punch is positioned inside the injection molding cavity, thereby forming a preform.

[0015] A blow molding cavity is configured to receive one of the preforms placed on a punch into it in a hot and soft state, and the blowing apparatus is configured to deliver pressurized gas into the hot and soft preform through one or more blow openings located within the punch when the punch carrying the preform is placed inside the blow molding cavity, thereby inflating and blow molding the preform to adopt the shape of a container defined by the inner surface of the blow molding cavity.

[0016] A transfer device can be optionally provided to transfer the punch from the injection molding cavity to the blow molding cavity and vice versa.

[0017] To cool the outer surface of the molded container that is in contact with the inner surface of the blow-molded cavity, the injection blow molding die includes a cooling device configured to cool the inner surface of the blow-molded cavity.

[0018] One or more blow openings are connected to a first conduit that communicates with a first pressurized gas supply source configured to supply pressurized gas through one or more blow openings at an overpressure higher than the blow pressure, and the blow pressure is a pressure suitable or sufficient to inflate the preform into the shape of a container by blow molding.

[0019] The blowing device is positioned within the punch, spaced apart from one or more blowing openings, and further comprises one or more exhaust ports connected to a second conduit that communicates with a pressure limiting device set to the blowing pressure. The pressure limiting device allows gas in the container to escape through one or more exhaust ports if the pressure exceeds the blowing pressure.

[0020] Therefore, once the preform is fully expanded into the container, the gas inside the container exceeds the blow pressure, generating a gas flow from one or more blow openings to one or more exhaust ports that cool the inner surface of the container. This, in addition to the cooling of the outer surface of the container performed by the cooling device, contributes to reducing the cooling time required for the finished container to be removed from the blow-molded cavity without deformation, thereby increasing the production rate.

[0021] When using the injection blow molding die of the present invention, the improvement achieved by simultaneously cooling the container wall both internally and externally contributes to forming a rigid outer shell on both sides of the plastic wall of the container, thus providing a stable structure for the container that prevents subsequent deformation.

[0022] According to a first modified example of the blowdown device, the pressure limiting device includes a pressure limiting valve located in the second conduit and configured to allow pressurized gas to escape from inside the container through one or more exhaust ports when the pressure inside the container exceeds the blowdown pressure.

[0023] All of the above features shown in Figures 1 to 3B of the drawings are related to the prior art, such as that disclosed in DE2605967A.

[0024] According to a second modified example of the blowing device that constitutes the core of the present invention, the pressure limiting device is equipped with a second pressurized gas supply source that communicates with a second conduit, and is configured to supply pressurized gas at the blowing pressure through one or more exhaust ports when the pressure inside the preform is less than or equal to the blowing pressure, and to recover the pressurized gas flowing out of the container through one or more exhaust ports when the pressure inside the preform exceeds the blowing pressure.

[0025] In a third modification of the blowing device, the pressure limiting device also communicates with the second conduit and includes a second pressurized gas supply source configured to supply pressurized gas through one or more exhaust ports at the blowing pressure, and is disposed within the second conduit. When the pressure inside the preform is below the blowing pressure, the pressurized gas is allowed to flow from the second pressurized gas supply source into the interior of the preform through one or more exhaust ports. When the pressure inside the container exceeds the blowing pressure, the pressure limiting valve is configured to allow the pressurized gas to escape from the interior of the container through the exhaust ports.

[0026] The injection blow mold further includes an opening and closing device configured to open and close one or more blow openings and one or more exhaust ports when a punch carrying the preform is disposed within the blow molding cavity.

[0027] For this purpose, the punch includes a base body and a molded body. The molded body is movable relative to the base body in an axial direction coaxial with the longitudinal axis of the punch between an open position and a closed position. In the open position, a gap is formed between the base body and the molded body to provide a proximal gas passage. In the closed position, no gap or gas passage exists between the base body and the molded body.

[0028] The punch further includes a valve body axially movable relative to the molded body between the open position and the closed position. In the open position, a gap is formed between the molded body and the valve body to provide a distal gas passage. In the closed position, no gap or gas passage exists between the molded body and the valve body.

[0029] In a first example, the proximal gas passage is connected to the second conduit such that the proximal gas passage constitutes one or more exhaust ports, and the distal gas passage is connected to the first conduit such that the distal gas passage constitutes one or more blow openings. An actuator is operatively connected to move the molded body between the open position and the closed position to open and close one or more exhaust ports, and an elastic element is disposed to bias the valve body to the closed position. This elastic element is set to allow the valve body to be moved to the open position by the influence of overpressure within the first conduit to open and close one or more blow openings.

[0030] In this first example, one or more blow openings provided by (or having) the distal gas passage are preferably formed as a single opening around the entire circumference of the longitudinal axis of the punch, and optionally are disposed in the distal region of the punch that defines a region of the preform intended to form the bottom of the container. One or more exhaust ports provided by the proximal gas passage are preferably formed as a single opening around the entire circumference of the longitudinal axis of the punch, and optionally are disposed in the proximal region of the punch that defines a region of the preform intended to form the shoulder of the container. [[ID=④]] [[ID=⑤]]

[0031] [[ID=⑥]] [[ID=⑦]]In the second example, the proximal gas passage is connected to a first conduit such that the proximal gas passage constitutes one or more blow openings, and the distal gas passage is connected to a second conduit such that the distal gas passage constitutes one or more exhaust ports. A first actuator is operatively connected to move the forming body between an open position and a closed position to open and close one or more blow openings, and a second actuator is operatively connected to move a valve body between an open position and a closed position to open and close one or more exhaust ports. [[ID=⑧]] [[ID=⑨]]

[0032] [[ID=⑩]] [[ID=⑪]]In this second embodiment, one or more blow openings provided by the proximal gas passage are preferably formed as a single opening around the entire circumference of the longitudinal axis of the punch, and optionally are disposed in the proximal region of the punch that defines a region of the preform intended to form the shoulder of the container. One or more exhaust ports provided by the distal gas passage are preferably formed as a single opening around the entire circumference of the longitudinal axis of the punch, and optionally are disposed in the distal region of the punch that defines a region of the preform intended to form the bottom of the container. [[ID=⑫]] [[ID=⑬]]

[0033] [[ID=⑭]] [[ID=⑮]]Throughout this specification, the term "proximal" is used to indicate a location near the base of the punch, and the term "distal" is used to indicate a location away from the base of the punch. [[ID=⑯]] [[ID=⑰]]

[0034] [[ID=⑱]] Without departing from the scope of the present invention, any one of the first, second, and third variations of the blow device can be combined with any one of the first and second embodiments of the injection blow molding die.

[0035] According to a second aspect, the present invention provides an injection blow molding method comprising the following conventional steps: - Firstly, the method comprises the step of receiving a punch into an injection molding cavity, wherein the punch defines the inner surface of a preform and the injection molding cavity defines the outer surface of the preform. -The method then includes the step of injecting molten plastic material into the injection molding cavity through at least one injection nozzle of an injection device when the punch is positioned inside the injection molding cavity to form one of the preforms. -In the next step, the method includes receiving a punch that places and supports one of the preforms on itself in a hot and soft state inside a blow molding cavity that defines the outer surface of the vessel to be obtained. -The method then includes the step of delivering pressurized gas into the interior of the preform through one or more blow openings located in the punch to inflate the preform into the container by blowing or blow molding the preform, when the punch carrying the preform is positioned inside the blow molding cavity.As a final conventional step, the method includes the step of cooling the outer surface of the container that is in contact with the blow molding cavity by a cooling device associated with (or accompanying) the blow molding cavity before removing the container from the mold.

[0036] The injection blow molding method of the present invention further includes, as an additional distinguishing (or identifying, or distinguishing) step, a step of supplying pressurized gas at an overpressure higher than the blow pressure through one or more blow openings by a first pressurized gas supply source communicating with a first conduit connected to one or more blow openings, wherein the blow pressure is suitable or sufficient to inflate a hot and soft preform into a container by blow molding; and a step of releasing the pressurized gas from inside the container through one or more exhaust ports provided in the punch at a position spaced apart from one or more blow openings, wherein the one or more exhaust ports are connected to a second conduit communicating with a pressure limiting device set to the blow pressure.

[0037] As a result, when the preform is fully expanded to the shape of the container, the gas inside the container exceeds the blow pressure, generating a gas flow from one or more blow openings to one or more exhaust ports, which cools the inner surface of the container. [Brief explanation of the drawing]

[0038] The aforementioned features and advantages will be better understood from the following detailed description of some exemplary and non-limiting embodiments with reference to the attached drawings. [Figure 1] Figure 1 is a cross-sectional view in the open position of a punch, injection molding cavity, and blow molding cavity belonging to an injection blow molding die according to the cited prior art (see DE2605967A). [Figure 2] Figure 2 is a cross-sectional view of the punch and blow-molding cavity shown in Figure 1 in the closed position. [Figure 3] Figures 3A and 3B are schematic diagrams of the punch and blow molding cavity of Figures 1 and 2, working in conjunction with a first modified example of the blowing apparatus in two different operating stages. [Figure 4]Figures 4A and 4B are schematic diagrams of the punch and blow molding cavity of Figures 1 and 2, working in cooperation with the blow apparatus in two different operating stages according to the principle of the present invention. [Figure 5] Figures 5A and 5B are schematic diagrams of the punch and blow molding cavity of Figures 1 and 2, working in cooperation with a third modification of the blow apparatus according to an additional embodiment that forms part of the present invention in two different operating stages. [Figure 6] Figure 6 is a cross-sectional view of a punch and blow molding cavity belonging to a second example injection blow molding die in the closed position. [Modes for carrying out the invention]

[0039] First, referring to Figures 1 and 2, reference numerals 1, 22, and 2 indicate the punch, injection molding cavity, and blow molding cavity of an injection blow molding die according to a first embodiment of the present invention, respectively. In Figures 1 and 2, several elements belonging to the blow molding apparatus are omitted as they will be described in detail below with reference to Figures 3A, 3B, 4A, 4B, and 5A, 5B.

[0040] The punch 1 has a longitudinal axis A, and the injection molding cavity 22 and the blow molding cavity 2 each have their respective longitudinal axes parallel to the longitudinal axis A of the punch 1, for example. A transfer device (not shown) is configured to transfer the punch from the inside of the injection molding cavity to the inside of the blow molding cavity, and vice versa.

[0041] Punch 1 has an outer surface that defines the inner surface of the preform 30a, and the injection molding cavity 22 formed within the injection molding block 23 defines the outer surface of the preform 30a. The injection molding cavity 22 is configured to receive punch 1 in a closed position (not shown), and the injection molding block 23 has an injection nozzle 24 through which an injection device can inject molten plastic material into the injection molding cavity 22, as is common in the prior art, and form the preform 30a by injection molding.

[0042] When the punch 1 and blow molding cavity 2 are aligned with each other as shown in Figures 1 and 2, they are movable between an open position (Figure 1) where the punch 1 and blow molding cavity 2 are separated from each other, and a closed position (Figure 2) where the punch 1 is coupled to the blow molding cavity 2 to form an injection blow molding die together.

[0043] The blow molding cavity 2 has an inner surface that defines the outer surface of the container 30b obtained by blowing or blow molding the preform 30a. The punch 1 holds one of the preforms 30a in a hot and soft state when the punch 1 is received into the blow molding cavity 2 to form the blow molding die. In the illustrated example, the preform 30a has a neck portion 31 formed in cooperation with two neck half-moulds 17a, 17b that move with the punch 1 and also connect to the blow molding cavity 2 in the die closing position.

[0044] The punch 1 comprises a base body 10, a molded body 11, and a valve body 13. The molded body 11 is movable relative to the base body 10 in an axial direction coaxial with the longitudinal axis A of the punch 1, between a closed position (Figure 1) in which there is no gap between the base body 10 and the molded body 11, and an open position (Figure 2) in which a gap is formed between the base body 10 and the molded body 11 to provide a proximal gas passage 12. The valve body 13 is movable axially relative to the molded body 11 between a closed position (Figure 1) in which there is no gap between the molded body 11 and the valve body 13, and an open position (Figure 2) in which a tip gas passage 14 is formed between the molded body 11 and the valve body 13.

[0045] The proximal gas passage 12 is formed around the entire circumference of the longitudinal axis A of the punch 1 and is located in the proximal region of the punch 1, defining the area of ​​the preform 30a intended to form the shoulder of the container 30b. The distal gas passage 14 is formed around the entire circumference of the longitudinal axis A of the punch 1 and is located in the distal region of the punch 1, defining the area of ​​the preform 30a intended to form the bottom of the container 30b. In the first embodiment shown in Figures 1 and 2, the distal gas passage 14 constitutes a blow opening 3 connected to the first conduit 5, and the proximal gas passage 12 constitutes an exhaust port 4 connected to the second conduit 7.

[0046] In this first embodiment of the prior art, an actuator 15 (symbolically shown in Figures 1 and 2) is operably connected to move the molded body 11 between an open position and a closed position, and an elastic element 20 is positioned to bias the valve body 13 to the closed position. The elastic element 20 is, for example, a helical spring set to move the valve body 13 to the open position due to the influence of a specific pressure in the first conduit 5.

[0047] The aforementioned blow apparatus is configured to deliver pressurized gas through the blow opening 3 into the hot and soft interior of the preform 30a in order to inflate the preform 30a against the inner surface of the blow molding cavity 2 in order to form one of the containers 21, and to release the gas inside the inflated container 30b through the exhaust port 4 under the specific conditions described below.

[0048] As a result, as shown by the thick arrow in Figure 2, once the container 30b is formed and before it is removed from the blow molding die, a gas flow is generated inside the container 30b from the blow opening 3 adjacent to the bottom of the container 30b to the exhaust port 4 adjacent to the shoulder of the container 30b, cooling the inner surface of the container 30b. For this reason, the blow opening 3 and the exhaust port 4 are positioned as far apart from each other as possible within the punch 1.

[0049] The blow molding cavity 2 is formed in a blow molding block 18, which has cooling conduits 19 located inside. The cooling device is configured to circulate cooling fluid through the cooling conduits 19 to cool the inner surface of the blow molding cavity 2 and the outer surface of the container 30b that is in contact with it. Therefore, both the inner and outer surfaces of the container 30b are cooled before the container 30b is removed from the blow molding die, reducing cycle time and increasing production speed.

[0050] Next, referring to Figures 3A, 3B, 4A, 4B, and 5A, 5B, respectively, in conjunction with the elements of the first embodiment, a first modified example (according to the prior art), a second modified example, and a third modified example of the blowing device, as well as their operation, will be described.

[0051] All of the first, second, and third modifications of the blowing apparatus share the common feature that a first conduit 5 to which the blowing opening 3 is connected is in communication with a first pressurized gas supply source 6 configured to supply pressurized gas through the blowing opening 3 at an overpressure OP, e.g., 12 bar, which is higher than the blowing pressure BP, e.g., 9 bar, e.g., and this blowing pressure BP is suitable for fully inflating the preform 30a until it is applied to the inner surface of the blow-molded cavity 2 and obtains the shape of the container 30b.

[0052] However, in the first, second, and third modified versions of the blowdown device, the second conduit 7 to which the exhaust port 4 is connected is in communication with a pressure limiting device set to the blowdown pressure BP. The pressure limiting device differs for each modified version and is configured to release the gas in the container 30b through the exhaust port 4 when the gas exceeds the blowdown pressure BP.

[0053] In the first modified example of the blowdown device shown in Figures 3A and 3B, the pressure limiting device communicating with the second conduit 7 connected to the exhaust port 4 simply comprises a pressure limiting valve 9 (see Figures 3A and 3B) set to the blowdown pressure BP.

[0054] As shown in Figure 3A, when the blow operation is performed with the second modification of the blow device, first, pressurized gas from the first pressurized gas supply source 6 is supplied at an overpressure OP to the inside of the preform 30a through the blow opening 3, causing the preform 30a to begin expanding, and the internal pressure rises from a pressure below the blow pressure BP toward the blow pressure BP, while the pressure limiting valve 9 remains closed.

[0055] Next, as shown in Figure 3B, when the preform 30a comes into contact with the inner surface of the blow-molded cavity 2 and fully expands to form the container 30b, the first pressurized gas supply source 6 continues to supply pressurized gas OP at overpressure through the blow opening 3, and the pressure inside the container 30b rises to a level exceeding the blow pressure BP, which causes the pressure limiting valve 9 to open, thereby allowing the gas inside the container 30b to escape through the exhaust port 4, thereby creating a cooling gas flow inside the container 30b from the blow opening 3 to the exhaust port 4.

[0056] In the second modified example of the blowdown device according to the first embodiment of the present invention shown in Figures 4A and 4B, the pressure limiting device communicating with the second conduit 7 connected to the exhaust port 4 includes a second pressurized gas supply source 8 communicating with the second conduit 7, and a pressure limiting valve 9 positioned in the second conduit 7 between the exhaust port 4 and the second pressurized gas supply source 8. The second pressurized gas supply source 8 supplies pressurized gas at the blowdown pressure BP from the exhaust port 4. The pressure limiting valve 9 is configured to allow pressurized gas at the blowdown pressure BP to flow into the preform 30a from the second pressurized gas supply source 8 via the exhaust port 4 when the internal pressure of the preform 30a is less than or equal to the blowdown pressure BP, and to release the pressurized gas from the inside of the container 30b via the exhaust port 4 when the internal pressure of the container 30b exceeds the blowdown pressure BP.

[0057] As shown in Figure 4A, when performing a blow operation using a second modified example of the blow device according to the principle of the present invention, first, pressurized gas from the first pressurized gas supply source 6 is supplied to the inside of the preform 30a via the air outlet 3 at an overpressure OP, and at the same time, pressurized gas from the second pressurized gas supply source 8 is supplied to the inside of the preform 30a via the pressure limiting valve 9 and the exhaust port 4 at the blow pressure BP, causing the preform 30a to start expanding, and the internal pressure rises from a pressure below the blow pressure BP toward the blow pressure BP.

[0058] Next, as shown in Figure 4B, when the preform 30a comes into contact with the inner surface of the blow-molded cavity 2 and fully expands to form the container 30b, the first pressurized gas supply source 6 continues to supply pressurized gas OP at overpressure through the blow opening 3, thereby causing the pressure inside the container 30b to exceed the blow pressure BP, thereby releasing the gas inside the container 30b through the exhaust port 4 and shifting the pressure limiting valve 9 to close the gas passage back to the second pressurized gas supply source 8, thus releasing the gas from the pressure limiting valve 9 and thus creating a cooling gas flow inside the container 30b from the blow opening 3 to the exhaust port 4.

[0059] In the third modified example of the blowdown device according to the present invention shown in Figures 5A and 5B, a pressure limiting device communicating with a second conduit 7 connected to the exhaust port 4 supplies pressurized gas through the exhaust port 4 at a blowdown pressure BP, and a second pressurized gas supply source 8 is provided which is configured to recover the pressurized gas flowing out of the container 30b through the exhaust port 4 when the pressure inside the container 30b exceeds the blowdown pressure BP.

[0060] As shown in Figure 5A, when blowing is performed using the third modified example of the blowing device, first, pressurized gas from the first pressurized gas supply source 6 is supplied to the inside of the preform 30a through the blow opening 3 at an overpressure OP, and at the same time, pressurized gas from the second pressurized gas supply source 8 is supplied to the inside of the preform 30a through the exhaust port 4 at the blow pressure OP. As a result, the preform 30a begins to expand, and the internal pressure rises from a pressure below the blow pressure BP toward the blow pressure BP.

[0061] Next, as shown in Figure 5B, once the preform 30a contacts the inner surface of the blow-molded cavity 2 and fully expands to form the container 30b, the first pressurized gas supply source 6 continues to supply pressurized gas OP at overpressure through the blow opening 3. This causes the pressure inside the container 30b to exceed the blow pressure BP, allowing the gas inside the container 30b to escape through the exhaust port 4 and return to the second pressurized gas supply source 8, creating a cooling gas flow inside the container 30b from the blow opening 3 to the exhaust port 4.

[0062] A blow-off device according to any one of the first, second, or third modifications may be equipped with other valve elements and / or accessories (not shown) commonly used in pneumatic circuits, which does not alter the operation of the blow-off device as described above.

[0063] When using the blowing apparatus according to Figures 3A and 3B or the first modified example shown in the figures, or the second modified example shown in Figures 4A and 4B, the compressed gas output generated by a pressure exceeding the blowing pressure BP passing through the exhaust port 4 and the pressure limiting valve 9 can, advantageously, be directed to a suitably sized tank (not shown) or a network of pressurized gas lines (not shown), and as a result, this pressurized gas close to the blowing pressure BP can be used for other purposes, such as driving a pneumatic piston or other accessory element of the same injection blow molding die or other machine or apparatus.

[0064] Therefore, the increased consumption of pressurized gas due to the cooling gas flow generated inside the container 30b is mitigated by the fact that the exhausted pressurized gas can be used to drive other pneumatic mechanisms.

[0065] Similar to the blow apparatus according to the second modification shown in Figures 4A and 4B or the third modification shown in Figures 5A and 5B, which implement the principles of the present invention, using a second pressurized gas supply source 8 in addition to the first pressurized gas supply source 6 makes it possible to reach the blow pressure BP more quickly in the container 30b, thereby contributing to further reducing cycle time and increasing the productivity of the system.

[0066] When using the blow device according to the third modified example shown in Figures 5A and 5B, it must be considered that the pressurized gas discharged from the exhaust port 4, which is returned to the second pressurized gas supply source 8, is relatively hot after cooling the inner surface of the container 30b, and preferably must be cooled before being supplied again into the container 30b in subsequent blow cycles.

[0067] When any one of the second or third modifications of the blow device is applied to the first embodiment shown in Figures 1 and 2, the elastic element 20 is configured to allow the valve body 13 to be moved to the open position due to the effect of the overpressure OP in the first conduit 5 provided by the first pressurized gas supply source 6.

[0068] Figure 6 shows an injection blow molding die according to a second example of the present invention, which differs primarily from the first example described above with reference to Figures 1 and 2, in that a proximal gas passage 12 is connected to a first conduit 5, thereby forming a blow opening 3, and a distal gas passage 14 is connected to a second conduit 7, thereby forming an exhaust port 4. The second example further differs from the first example in that a second actuator 16 (indicated by a symbol in Figure 6) is operably connected to move a valve body 13 between an open position and a closed position instead of an elastic element.

[0069] The blow opening 3 is formed around the entire circumference of the longitudinal axis A of the punch 1 and is located in the proximal region of the punch 1, defining the area of ​​the preform 30a intended to form the shoulder of the container 30b, while the exhaust port 4 is formed around the entire circumference of the longitudinal axis A of the punch 1 and is located in the distal region of the punch 1, defining the area of ​​the preform 30a intended to form the bottom of the container 30b. Thus, in this second embodiment, the cooling gas flow generated inside the container 30b (indicated by arrows in Figure 6) flows in the opposite direction to that in the first embodiment, which yields equivalent results.

[0070] Any one of the second and third modifications of the blowing apparatus shown in Figures 3A, 3B, 4A, 4B, and 5A, 5B can be applied to the second embodiment shown in Figure 6.

[0071] In both the first and second examples of injection blow molding dies shown in Figures 1, 2, and 6, the blow molding cavity 2 has a cylindrical inner surface intended to form the cylindrical body portion of the container 30b, while two neck-shaped half molds 17a, 17b are intended to form the neck and shoulder portions of the container 30b. This allows the mold to open and the container 30b to be extracted axially from the blow molding cavity 2. However, alternatively, without departing from the scope of the present invention, a pair of radially opening half blow-moulding cavities may be provided to form containers with more complex body shapes.

[0072] The present invention also provides an injection blow molding method that can be carried out by either of the first or second examples of an injection blow molding die in cooperation with either of the second or third modifications of a blow apparatus, the method comprising the following steps known in the art: - The first step is to receive a punch 1 defining the inner surface of the preform 30a into an injection molding cavity 22 defining the outer surface of the preform 30a, and then inject molten plastic material into the injection molding cavity 22 through at least one injection nozzle 24 of the injection device when the punch 1 is positioned inside the injection molding cavity 22 to form one of the preforms 30a. -The next step is to receive the punch 1, which has one of the preforms 30a placed on the punch 1 in a hot and soft state, into the blow molding cavity 2, wherein the blow molding cavity 2 defines the outer surface of the container 30b obtained by blowing the preform 30a. -The next step is to deliver pressurized gas at an overpressure OP into the interior of the preform 30a through at least one blow opening 3 located in the punch 1, when the punch 1 supporting the preform 30a is positioned inside the blow molding cavity 2, wherein the pressurized gas at the overpressure OP is supplied by a first pressurized gas supply source 6, and the overpressure OP is suitable for inflating the preform 30a into the container 30b by blow molding, or exceeds a sufficient blow pressure BP. -Finally, when the pressure inside the container 30b exceeds the blow pressure BP, the pressurized gas is released from inside the container 30b through an exhaust port 4 provided in the punch 1 and positioned spaced apart from the blow opening 3, wherein the exhaust port 4 is connected to a second conduit 7 that communicates with a pressure limiting device set to the blow pressure BP.

[0073] As a result, when the gas inside the container 30b exceeds the blow pressure BP, a gas flow is generated from the blow opening 3 to the exhaust port 4. This gas flow cools the inner surface of the container 30b, while the outer surface of the container 30b that is in contact with the blow molding cavity 2 is cooled by the cooling device attached to the blow molding cavity 2.

[0074] According to the principles of the present invention, the method further includes the following: - A second pressurized gas supply source (8) communicating with the second conduit (7) supplies pressurized gas at blow pressure (BP) through at least one exhaust port (4), and when the pressure inside the container (30b) exceeds the blow pressure (BP), the pressurized gas flowing out of the container (30b) through at least one exhaust port (4) is recovered.

[0075] The scope of the present invention is defined by the appended claims. The following is the invention as originally described in the application. <Claim 1> Injection blow molding die, A punch (1) that defines the inner surface of the preform (30a), A blow molding cavity (2) defining the outer surface of a container (30b) obtained by blowing an injected preform (30a), wherein the blow molding cavity (2) is configured to receive the punch (1) into which the punch (1) is equipped with one of the preforms (30a) placed on the punch (1) in a hot and soft state, A blowing apparatus configured to deliver pressurized gas into the interior of the preform (30a) through at least one blow opening (3) located in the punch (1) when the punch (1) supporting the preform (30a) is positioned inside the blow molding cavity (2), It has, The at least one blow opening (3) is connected to a first conduit (5) which communicates with a first pressurized gas supply source (6) configured to supply pressurized gas through the at least one blow opening (3) at an overpressure (OP) higher than the blow pressure (BP), the blow pressure (BP) being a pressure suitable for blowing the preform (30a) into the container (30b), The blow device further comprises at least one exhaust port (4) located within the punch (1) at a position spaced apart from the at least one blow opening (3), and connected to a second conduit (7) that communicates with a pressure limiting device set to the blow pressure (BP), wherein when the pressure limiting device exceeds the blow pressure (BP), it allows the gas in the container (30b) to escape through the at least one exhaust port (4). As a result, a gas flow is generated inside the container (30b) from the at least one blow opening (3) to the at least one exhaust port (4), cooling the inner surface of the container (30b). An injection blow molding die characterized in that the pressure limiting device comprises a second pressurized gas supply source (8) which is in communication with the second conduit (7), supplies pressurized gas through the at least one exhaust port (4) at the blow pressure (BP), and is configured to recover the pressurized gas flowing out of the container (30b) through the at least one exhaust port (4) when the pressure inside the container (30b) exceeds the blow pressure (BP). <Claim 2> The injection blow molding die according to claim 1, wherein the pressure limiting device comprises a pressure limiting valve (9) disposed in the second conduit (7) and configured to allow the pressurized gas to escape from the inside of the container (30b) through the at least one exhaust port (4) when the pressure inside the container (30b) exceeds the blow pressure (BP). <Claim 3> The injection blow molding die according to claim 1 or 2, further comprising a cooling device configured to cool the inner surface of the blow molding cavity (2) and the outer surface of the container (30b) in contact with it. <Claim 4> The injection blow molding die according to claim 1, 2, or 3, wherein the pressure limiting device comprises a second pressurized gas supply source (8) that communicates with the second conduit (7) and is configured to supply pressurized gas through the at least one exhaust port (4) at the blow pressure (BP), and a pressure limiting valve (9) disposed within the second conduit (7) and configured to allow the pressurized gas to flow from the second pressurized gas supply source (8) into the preform (30a) through the at least one exhaust port (4) when the pressure inside the preform (30a) is less than or equal to the blow pressure (BP), and to allow the pressurized gas to escape from the container (30b) through the at least one exhaust port (4) when the pressure inside the container (30b) exceeds the blow pressure (BP). <Claim 5> The injection blow molding die according to any one of claims 1 to 4, further comprising an opening / closing device configured to open and close the at least one blow opening (3) and the at least one exhaust port (4) when the punch (1) carrying the preform (30a) is positioned inside the blow molding cavity (2). <Claim 6> The injection blow molding die according to claim 5, wherein the punch (1) comprises a base (10) and a molded body (11), and the molded body (11) is movable relative to the base (10) in an axial direction coaxial with the longitudinal axis (A) of the punch (1) between an open position in which a gap between the base (10) and the molded body (11) provides a proximal gas passage (12) and a closed position in which there is no gap or gas passage between the base (10) and the molded body (11). <Claim 7> The injection blow molding die according to claim 6, wherein the punch (1) further comprises a valve body (13), the valve body being movable in the axial direction relative to the molded body (11) between an open position in which a gap between the molded body (11) and the valve body (13) provides a distal gas passage (14) and a closed position in which there is no gap or gas passage between the molded body (11) and the valve body (13). <Claim 8> The injection blow molding die according to claim 7, wherein the proximal gas passage (12) is connected to the second conduit (7) and constitutes the at least one exhaust port (4), and the distal gas passage (14) is connected to the first conduit (5) and constitutes the at least one blow opening (3). <Claim 9> The injection blow molding die according to claim 7, wherein the proximal gas passage (12) is connected to the first conduit (5) and constitutes the at least one blow opening (3), and the distal gas passage (14) is connected to the second conduit (7) and constitutes the at least one exhaust port (4). <Claim 10> The injection blow molding die according to claim 8 or 9, further comprising an actuator (15) movably connected to move the molded body (11) between the open position and the closed position. <Claim 11> The injection blow molding die according to claim 8, further comprising an elastic element (20) disposed to bias the valve body (10) to the closed position, wherein the elastic element (20) is configured to allow the valve body (10) to move to the open position due to the influence of the overpressure (OP) in the first conduit (5). <Claim 12> The injection blow molding die according to claim 9, further comprising a second actuator (16) movably connected to move the valve body (10) between the open position and the closed position. <Claim 13> The injection blow molding die according to claim 7, 8, or 9, wherein the proximal gas passage (12) and the distal gas passage (14) are formed around the entire circumference of the longitudinal axis (A) of the punch (1). <Claim 14> An injection blow molding die according to any one of claims 1 to 4, wherein the at least one blow opening (3) is provided by a distal gas passage (14) located in the distal region of the punch (1) that is formed around the entire circumference of the longitudinal axis (A) of the punch (1) and defines a region of the preform (30a) intended to form the bottom of the container (30b), and the at least one exhaust port (4) has a proximal gas passage (12) located in the proximal region of the punch (1) that is formed around the entire circumference of the longitudinal axis (A) of the punch (1) and defines a region of the preform (30a) intended to form the shoulder of the container (30b). <Claim 15> An injection blow molding die according to any one of claims 1 to 4, wherein the at least one blow opening (3) is provided by a proximal gas passage (12) located in the proximal region of the punch (1) that is formed around the entire circumference of the longitudinal axis (A) of the punch (1) and defines a region of the preform (30a) intended to form the shoulder of the container (30b), and the at least one exhaust port (4) has a distal gas passage (14) located in the distal region of the punch (1) that is formed around the entire circumference of the longitudinal axis (A) of the punch (1) and defines a region of the preform (30a) intended to form the bottom of the container (30b). <Claim 16> An injection blow molding method, A step of receiving a punch (1), wherein the punch (1) is provided with an injection preform (30a) that is placed on the punch (1) in a hot and soft state, inside a blow molding cavity (2) that defines the outer surface of a container (30b) obtained by blowing the preform (30a), When the punch (1) supporting the preform (30a) is positioned inside the blow molding cavity (2), the step of delivering pressurized gas into the interior of the preform (30a) through at least one blow opening (3) positioned in the punch (1), A step of supplying pressurized gas through at least one blow opening (3) at an overpressure (OP) higher than the blow pressure (BP) by a first pressurized gas supply source (6) communicating with a first conduit (5), wherein the blow pressure (BP) is a pressure suitable for blowing the preform (30a) into the container (30b), The pressurized gas is released from the container (30b) when the pressure inside the container (30b) is higher than the blow pressure (BP) by connecting the at least one exhaust port (4) to a second conduit (7) that communicates with a pressure limiting device set to the blow pressure (BP), through an at least one exhaust port (4) provided in the punch (1) and positioned spaced apart from the at least one blow opening (3), and by connecting the at least one exhaust port (4) to a second conduit (7) that communicates with a pressure limiting device set to the blow pressure (BP). It has, As a result, when the gas inside the container (30b) exceeds the blow pressure (BP), a gas flow is generated from the at least one blow opening (3) to the at least one exhaust port (4), and the gas flow cools the inner surface of the container (30b). The method described above is An injection blow molding method further comprising the steps of supplying pressurized gas at the blow pressure (BP) through the at least one exhaust port (4) by a second pressurized gas supply source (8) communicating with the second conduit (7), and recovering the pressurized gas flowing out of the container (30b) through the at least one exhaust port (4) when the pressure inside the container (30b) exceeds the blow pressure (BP).

Claims

1. Injection blow molding die, A punch (1) that defines the inner surface of the preform (30a), A blow molding cavity (2) that defines the outer surface of a container (30b) obtained by blowing an injected preform (30a), wherein the blow molding cavity (2) is configured to receive the punch (1) into which the punch (1) is equipped with one of the preforms (30a) that are placed on the punch (1) in a hot and soft state, A blowing apparatus configured to deliver pressurized gas into the interior of the preform (30a) through at least one blow opening (3) located in the punch (1) when the punch (1) supporting the preform (30a) is positioned inside the blow molding cavity (2), It has, The at least one blow opening (3) is connected to a first conduit (5) which communicates with a first pressurized gas supply source (6) configured to supply pressurized gas through the at least one blow opening (3) at an overpressure (OP) higher than the blow pressure (BP), the blow pressure (BP) being a pressure suitable for blowing the preform (30a) into the container (30b), The blow device further comprises at least one exhaust port (4), which is located within the punch (1) at a position spaced apart from the at least one blow opening (3), and is connected to a second conduit (7) that communicates with a pressure limiting device configured to release gas from inside the container (30b) through the at least one exhaust port (4) when the gas pressure inside the container (30b) exceeds the blow pressure (BP), As a result, a gas flow is generated inside the container (30b) from the at least one blow opening (3) to the at least one exhaust port (4), cooling the inner surface of the container (30b). An injection blow molding die characterized in that the pressure limiting device comprises a second pressurized gas supply source (8) which is in communication with the second conduit (7), supplies pressurized gas through the at least one exhaust port (4) at the blow pressure (BP), and recovers the pressurized gas flowing out of the container (30b) through the at least one exhaust port (4) when the pressure inside the container (30b) exceeds the blow pressure (BP).

2. The injection blow molding die according to claim 1, wherein the pressure limiting device comprises a pressure limiting valve (9) disposed in the second conduit (7) and configured to allow the pressurized gas to escape from the inside of the container (30b) through the at least one exhaust port (4) when the pressure inside the container (30b) exceeds the blow pressure (BP).

3. The injection blow molding die according to claim 1 or 2, further comprising a cooling device configured to cool the inner surface of the blow molding cavity (2) and the outer surface of the container (30b) in contact with it.

4. The injection blow molding die according to claim 1, 2, or 3, wherein the pressure limiting device comprises: a second pressurized gas supply source (8) that communicates with the second conduit (7) and is configured to supply pressurized gas through the at least one exhaust port (4) at the blow pressure (BP); and a pressure limiting valve (9) disposed within the second conduit (7) and configured to allow the pressurized gas to flow from the second pressurized gas supply source (8) into the preform (30a) through the at least one exhaust port (4) when the pressure inside the preform (30a) is less than or equal to the blow pressure (BP), and to allow the pressurized gas to escape from the container (30b) through the at least one exhaust port (4) when the pressure inside the container (30b) exceeds the blow pressure (BP).

5. The injection blow molding die according to any one of claims 1 to 4, further comprising an opening / closing device configured to open and close the at least one blow opening (3) and the at least one exhaust port (4) when the punch (1) supporting the preform (30a) is positioned inside the blow molding cavity (2).

6. The injection blow molding die according to claim 5, wherein the punch (1) comprises a base body (10) and a molded body (11), and the molded body (11) is movable relative to the base body (10) in an axial direction coaxial with the longitudinal axis (A) of the punch (1) between an open position in which a gap between the base body (10) and the molded body (11) provides a proximal gas passage (12) and a closed position in which there is no gap or gas passage between the base body (10) and the molded body (11).

7. The injection blow molding die according to claim 6, wherein the punch (1) further comprises a valve body (13), and the valve body is movable in the axial direction relative to the molded body (11) between an open position in which a gap between the molded body (11) and the valve body (13) provides a distal gas passage (14) and a closed position in which there is no gap or gas passage between the molded body (11) and the valve body (13).

8. The injection blow molding die according to claim 7, wherein the proximal gas passage (12) is connected to the second conduit (7) and constitutes the at least one exhaust port (4), and the distal gas passage (14) is connected to the first conduit (5) and constitutes the at least one blow opening (3).

9. The injection blow molding die according to claim 7, wherein the proximal gas passage (12) is connected to the first conduit (5) and constitutes the at least one blow opening (3), and the distal gas passage (14) is connected to the second conduit (7) and constitutes the at least one exhaust port (4).

10. The injection blow molding die according to claim 8 or 9, further comprising an actuator (15) movably connected to move the molded body (11) between the open position and the closed position.

11. The injection blow molding die according to claim 8, further comprising an elastic element (20) disposed to bias the valve body (10) to the closed position, wherein the elastic element (20) is configured to allow the valve body (10) to move to the open position due to the influence of the overpressure (OP) in the first conduit (5).

12. The injection blow molding die according to claim 9, further comprising a second actuator (16) movably connected to move the valve body (10) between the open position and the closed position.

13. The injection blow molding die according to claim 7, 8, or 9, wherein the proximal gas passage (12) and the distal gas passage (14) are formed around the entire circumference of the longitudinal axis (A) of the punch (1).

14. An injection blow molding die according to any one of claims 1 to 4, wherein the at least one blow opening (3) is provided by a distal gas passage (14) located in the distal region of the punch (1) that is formed around the entire circumference of the longitudinal axis (A) of the punch (1) and defines a region of the preform (30a) intended to form the bottom of the container (30b), and the at least one exhaust port (4) has a proximal gas passage (12) located in the proximal region of the punch (1) that is formed around the entire circumference of the longitudinal axis (A) of the punch (1) and defines a region of the preform (30a) intended to form the shoulder of the container (30b).

15. The injection blow molding die according to any one of claims 1 to 4, wherein the at least one blow opening (3) is provided by a proximal gas passage (12) located in the proximal region of the punch (1) that is formed around the entire circumference of the longitudinal axis (A) of the punch (1) and defines a region of the preform (30a) intended to form the shoulder of the container (30b), and the at least one exhaust port (4) has a distal gas passage (14) located in the distal region of the punch (1) that is formed around the entire circumference of the longitudinal axis (A) of the punch (1) and defines a region of the preform (30a) intended to form the bottom of the container (30b).

16. An injection blow molding method, A step of receiving a punch (1), wherein the punch (1) is provided with an injection preform (30a) that is placed on the punch (1) in a hot and soft state, inside a blow molding cavity (2) that defines the outer surface of a container (30b) obtained by blowing the preform (30a), When the punch (1) supporting the preform (30a) is positioned inside the blow molding cavity (2), the step of delivering pressurized gas into the interior of the preform (30a) through at least one blow opening (3) positioned in the punch (1), A step of supplying pressurized gas through at least one blow opening (3) at an overpressure (OP) higher than the blow pressure (BP) by a first pressurized gas supply source (6) communicating with a first conduit (5), wherein the blow pressure (BP) is a pressure suitable for blowing the preform (30a) into the container (30b), The pressurized gas is released from the container (30b) when the pressure inside the container (30b) is higher than the blow pressure (BP) by connecting the at least one exhaust port (4) to a second conduit (7) that communicates with a pressure limiting device set to the blow pressure (BP), through an at least one exhaust port (4) provided in the punch (1) and positioned spaced apart from the at least one blow opening (3), and by connecting the at least one exhaust port (4) to a second conduit (7) that communicates with a pressure limiting device set to the blow pressure (BP). It has, As a result, when the gas inside the container (30b) exceeds the blow pressure (BP), a gas flow is generated from the at least one blow opening (3) to the at least one exhaust port (4), and the gas flow cools the inner surface of the container (30b). The method described above is An injection blow molding method further comprising the steps of supplying pressurized gas at the blow pressure (BP) through the at least one exhaust port (4) by a second pressurized gas supply source (8) communicating with the second conduit (7), and recovering the pressurized gas flowing out of the container (30b) through the at least one exhaust port (4) when the pressure inside the container (30b) exceeds the blow pressure (BP).

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