blow or stretch-blow machines

Abstract

A blow or stretch blow machine has multiple dies, each die having a front, a back, and a bottom. Each die includes a first half-die and a second half-die hinged about a hinge axis and also includes a base. Each die includes an actuation mechanism for synchronously actuating the half-die and the base. The actuation mechanism is actuated by an actuator of the die and is independent of the machine's motor structure. The base cooperates with a suitable forming part to cyclically form a closed cavity adapted to receive a preheated preform and allow the preform to expand by blow or stretch blow within the cavity to obtain a bottle or container. The base is wedge-shaped and includes a horizontal closed surface and an inclined surface. The horizontal closed surface faces the bottom of the die. The actuation mechanism of the base includes a wedge element having an inclined surface that slopes downward toward the front of the die. The inclined surface of the base is slidably connected to the inclined surface of the wedge element.

Description

Technical Field

[0001] The present invention relates to a blow or stretch blow machine for use with preforms made of polymer materials, the blow or stretch blow machine being adapted to transform the preforms into bottles or containers, and more specifically, the present invention relates to a molding half-mold opening and closing mechanism. Background Technology

[0002] Obtaining bottles or containers by blowing a properly heated preform into a mold of the desired shape is a well-known technique in the packaging industry (specifically, the industry used to manufacture bottles or containers).

[0003] There are essentially two different techniques (simple blow and stretch blow), which involve the pneumatic blowing of preforms in a mold and the parallel mechanical stretching. In both cases, the preform must arrive at the blow or stretch blow machine under thermal conditions corresponding to the material's softening point in order to allow for plastic deformation within the mold.

[0004] Blowing or stretch blowing machines for preforms are known and include multiple openable dies comprising two halves hinged at one end and actuated by suitably arranged levers sized to open and close the halves in a manner synchronized with predetermined loading steps of the preform and unloading steps of the formed bottle. These levers are typically operated via forming cam couplings adapted to provide alternating movements with patterns defined by the shape of the cams themselves.

[0005] In a rotary machine, multiple molds are arranged radially around a central axis of rotation, and the devices for opening and closing the molds are synchronized with the movements of other devices that cooperate in the operation of the machine (e.g., motion devices for allowing preforms to enter and bottles to leave, or blowing and moving devices for different parts of the molds).

[0006] Traditional mold motion systems and opening / closing systems are complex and, in particular, not very versatile. In fact, to modify the opening / closing contour, the cam system must be replaced with a different cam system (where the cam contour corresponds to the new motion). Furthermore, using complex mechanical motion transmission systems means that conventional machines suffer from high wear and tear and therefore require frequent and careful maintenance.

[0007] Semi-die opening / closing systems are also known, which involve the use of dedicated motorized structures. However, in this case (especially when moving the base plate), the rods used are complex, which may lead to more maintenance and therefore more system downtime. Furthermore, the presence of motorized structures increases the size of the blow or stretch blow unit, which is incompatible with the requirement for a compact and small system. Summary of the Invention

[0008] The problem solved by this invention is to make a blow or stretch blow machine available for making bottles from plastic materials. This blow or stretch blow machine overcomes the above-mentioned disadvantages and is therefore simpler in construction, requires less maintenance, and is more compact.

[0009] Such problems are solved by machines as outlined in the appended claims, the definitions of which form part of this specification.

[0010] Specifically, the present invention relates to a blow or stretch blow molding machine for forming bottles or containers from polymer materials. The machine has a plurality of molds movable on a conveying system, wherein each mold has a front, a back, and a bottom, and each mold includes a first half-mold and a second half-mold hinged about a hinge axis and includes a base. Each mold includes an actuation mechanism for synchronously actuating these half-molds and the base to cooperate with suitable forming portions to cyclically form closed cavities. The actuation mechanism is actuated by an actuator. Independent of the machine's motor structure, the closed cavity is adapted to receive a preheated preform and allows the preform to expand to obtain a bottle or container by blowing or stretching within the blown cavity. The blown or stretch blown machine is characterized by a wedge-shaped base that includes a horizontal closed surface and an inclined surface, wherein the horizontal closed surface faces the bottom of the mold, and wherein the actuation mechanism of the base includes a wedge element having an inclined surface that slopes downward toward the front of the mold, the inclined surface of the base and the inclined surface of the wedge element being slidably connected to each other. Attached Figure Description

[0011] Other features and advantages of the invention will become more apparent from the description of some embodiments given below by way of non-limiting, symbolic example, with reference to the accompanying drawings, in which:

[0012] Figure 1 A top perspective view of a blowing or stretching blowing unit according to the present invention is shown;

[0013] Figure 2 It shows Figure 1A simplified side cross-sectional view of the blow or stretch blow unit in its initial operating state (where the die support and bracket have been omitted);

[0014] Figure 3 It shows in Figure 2 Views of the blowing or stretching blowing unit in different operating states;

[0015] Figure 4 It shows Figure 1 A simplified top cross-sectional view of the blow or stretch blow unit in its initial operating state (where the die support and bracket have been omitted);

[0016] Figure 5 It shows in Figure 4 Views of the blowing or stretching blowing unit in different operating states. Detailed Implementation

[0017] Referring to the accompanying drawings, reference numeral 1 generally indicates the injection molding die for the container in a blow or stretch blow machine. Typically, the blow or stretch blow machine according to the invention is rotary and includes a plurality of dies 1 arranged radially relative to the substantially vertical axis of rotation of the machine.

[0018] By rotating around the machine's axis of rotation, each mold 1 is cyclically transported to a loading station for loading preforms and / or an unloading station for unloading bottles C obtained from the preforms. Blowing or stretch blowing is performed between the loading of the preforms and the unloading of the bottles.

[0019] Mold 1 includes a front, a back, and a bottom.

[0020] Each mold 1 is mounted on a bracket 20 fixed to a turntable, and each mold includes a first half-mold 2a and a second half-mold 2b hinged around a hinge axis 3, which is generally parallel to the rotation axis of the machine. The hinge axis 3 is located at one end of the half-molds 2a, 2b facing the machine axis (the back of the mold 1), while the half-molds 2a, 2b include edges 9a, 9b at the other end (the front of the mold 1), which are designed to face each other when the mold 1 is closed.

[0021] Each half-mold 2a, 2b is C-shaped in cross-section and includes front portions 37a, 37b, side portions 38a, 38b and rear portions 39a, 39b respectively.

[0022] Therefore, the first half-mold 2a and the second half-mold 2b can be in the closed mold structure around the hinge axis 3. Figure 4 ) and opening the mold structure ( Figure 1 and Figure 5They can rotate between each other. The half-molts 2a and 2b can therefore open / close like the two shells of a bivalve.

[0023] The mold 1 includes a base 4 (wherein the base is adapted to cooperate with half molds 2a, 2b to close the bottom of the mold 1) and a device for vertically moving the base plate (base) for cyclically forming a closed cavity suitable for receiving a preheated preform, and for allowing the preform to expand by blow or stretch blow within the cavity to obtain a bottle or container.

[0024] The half-molds 2a and 2b include outer surfaces 5a and 5b and inner surfaces 6a and 6b, respectively. Corresponding forming parts S are applied to the inner surfaces 6a and 6b. As the mold closes, these forming parts become a whole, reverse-simulating the shape of the bottle C to be obtained from the preform and defining the space for the expansion of the preform.

[0025] In some embodiments, such a forming portion S can be separated from and is replaceable from the half molds 2a, 2b to allow for the formation of bottles C with different shapes and sizes. Thus, replacing the forming portion S is sufficient to begin production of different bottles.

[0026] The half molds 2a and 2b include bottom openings from which the lower part of the molding portion S protrudes. Furthermore, the molding portion S has a bottom opening at the bottom portion of the bottle to be obtained, and the bottom opening of the molding portion is adapted to be closed by the alternating movement of the aforementioned base 4.

[0027] The closing element 19 of the mold 1 is rotatably mounted on one of the two half molds 2a, 2b (in the example in the figure, on the right half mold 2a), and the closing element is adapted to keep the half molds 2a, 2b engaged during blow or stretch blow.

[0028] The motion mechanism of the closing element 19 and the holding system of the half mold are described in patent application EP15164317.8 filed by the same applicant on April 20, 2015.

[0029] The mold 1 also includes a support 10, which includes an L-shaped element 10a to which the mold 1 is hinged.

[0030] The blowing and stretch blowing machine for containers according to the invention is characterized by an opening / closing system comprising half-dies 2a, 2b and a base 4, which has an independent motorized structure instead of an actuating cam. Therefore, each die 1 of the blowing or stretch blowing machine includes its own motorized structure that opens / closes the half-dies 2a, 2b and the base 4 and independently of the machine's motorized structure that sequentially conveys the dies 1 along the working path.

[0031] The aforementioned motor structure for opening / closing the half-molds 2a, 2b and the base 4 is an actuator utilizing rotary motion. A preferred example of this actuator is a stepper motor, and more preferably, a rotary brushless motor.

[0032] Therefore, the mold 1 according to the invention includes a horizontally arranged actuator 30 that moves a single synchronous actuation mechanism 40 of the half molds 2a, 2b and the base 4.

[0033] As described in more detail below, this embodiment also allows for better control of the blowing or stretch blowing process, and due to the absence of a mechanical cam, this embodiment has the advantage of reducing machine vibration, noise, and wear.

[0034] In the example shown, actuator 30 is either a rotary brushless motor or a stepper motor and is fixed to bracket 20. Bracket 20 includes a plate 20a extending onto mold 1, such that half-molds 2a, 2b are accommodated between L-shaped element 10a and plate 20a. Rotary actuator 30 is connected to Archimedes screw 51 via transmission member 50.

[0035] The actuation mechanism 40 includes a sliding member 33 having a tubular cavity 61 arranged along a horizontal line located on a vertical plane dividing the two half-molds 2a and 2b. An Archimedean screw 51 is inserted into the cavity 61. Appropriate bosses on the inner surface of the tubular cavity 61 cooperate with the grooves of the Archimedean screw 51, such that the sliding member 33 advances or retracts according to the direction of rotation of the Archimedean screw 51 as it rotates.

[0036] The sliding member 33 is associated with a first slider 34a, which is located above the sliding member 33 and slidably mounted to the guide device 35. The guide device 35 is fixed and mounted on the bracket 20. The sliding member 33 can therefore slide between an advance position (or closed position) and a retracted position (or open position).

[0037] The sliding member 33 is also integral with the connecting element 33' at the bottom, which in turn is connected to the second sliding member 34b, which is slidably mounted on the corresponding guide device 35' fixed to the bracket 20.

[0038] The connecting element 33' is associated with the two half molds 2a and 2b via corresponding connecting rods 36a and 36b.

[0039] The first ends of the two connecting rods 36a and 36b are coaxially hinged to the connecting element 33', while the other ends are respectively hinged to the corresponding engaging elements 70a and 70b between the side portions 38a and 38b and the rear portions 39a and 39b of the half molds 2a and 2b. Thus, specifically as follows... Figure 4 and Figure 5 As shown, when the sliding member 33 is in the forward position, the half molds 2a and 2b face each other along edges 9a and 9b and the mold 1 is closed; conversely, when the sliding member 33 is in the retracted position ( Figure 5 When the connecting rods 36a and 36b act on the hinge points that are hinged to the half molds 2a and 2b, they bring these half molds to the open position.

[0040] It is evident that the sliding member 33 corresponds to different degrees of opening of the half-molds 2a and 2b along all intermediate positions of the guide device 35. As will be explained better below, the possibility of limiting the different degrees of opening of the half-molds 2a and 2b according to the size of the container to be formed can optimize processing time: in fact, for small containers, it is not necessary to fully open the mold to load the preform and unload the molded container, thus reducing the total time for each work step and thereby speeding up the production cycle. Since it is still possible to partially open the half-molds 2a and 2b to load smaller preforms, the same applies to larger containers.

[0041] Another advantage associated with only partially opening the half-molds 2a and 2b is the reduction of forces during travel and vibrations in the machine.

[0042] The sliding member 33 is also operatively connected to the opening-closing mechanism of the base 4.

[0043] The second sliding member 34b is integral with the L-shaped element 41, which includes a horizontal portion 41a facing the front of the mold surface 1. The front of the horizontal portion 41a includes a wedge-shaped element 41b having an inclined surface 41c that slopes downward toward the front of the mold 1.

[0044] The horizontal portion 41a of the L-shaped element 41 slides through the bracket 20, specifically through the vertical plate 20b facing the front of the mold 1 and including the guide, on which the third slider 34c associated with the base 4 slides vertically.

[0045] The base 4 is wedge-shaped and includes a horizontal closed surface 4a and an inclined surface 4b. The horizontal closed surface faces the bottom of the mold 1, and the inclination of the inclined surface is complementary to the inclination of the wedge element 41b. The inclined surface 4b includes a fourth slider 34d, which slides in a guide formed on the wedge element 41b.

[0046] Therefore, when the sliding element 33 is in the retracted position under the rotation of the Archimedes screw 51 ( Figure 2 When the sliding element 33 and therefore the wedge-shaped element 41b are in the retracted position, the base 4 is in a lower open position. On the other hand, when the sliding element 33 and therefore the wedge-shaped element 41b are in the forward position ( Figure 3 When the base 4 is in the closed position, it is pushed upward by the action of the wedge element.

[0047] The specific advantage of this mechanism is that it minimizes the connecting mechanisms, thus making it structurally simple and requiring almost no maintenance.

[0048] In a preferred embodiment, the blow or stretch blow machine or die 1 includes a command and control unit configured to manage motion laws for opening / closing individual dies 1, thereby enabling predetermined opening / closing cycles for each type of container C to be formed. For example, when the container C to be formed is small, the die can be partially opened, thereby increasing productivity, as described above.

[0049] Compared to traditional machines, this is a significant advantage because it eliminates the need to replace mechanical parts (cam profiles).

[0050] In some embodiments, the command and control unit is configured to manage the overall operation of the machine and perform the following functions:

[0051] - Read the pressure sensor inside the mold;

[0052] - Command processing time;

[0053] - Adjust the parameters of the blowing process;

[0054] -Actuation alarm signal;

[0055] - Adjust the heating of the preform;

[0056] - Adjust the machine's operating speed.

[0057] It is obvious that only a few specific embodiments of the present invention have been described, but those skilled in the art will be able to make all necessary changes to adapt these embodiments to specific applications without departing from the scope of protection of the present invention.

Claims

1. A blowing machine for blowing containers of polymeric material, said machine having a plurality of moulds (1) movable on a conveying system, wherein, Each of the molds (1) has a front, a back, and a bottom, each of the molds includes a first half-mold (2a) and a second half-mold (2b) hinged about a hinge axis (3) and also includes a base (4), wherein each of the molds (1) includes an actuation mechanism (40) for synchronously actuating the half-molds (2a, 2b) and the base (4) to cooperate with a suitable forming part (S) to cyclically form a closed cavity, the actuation mechanism being actuated by an actuator (30) of the mold, the actuation mechanism being independent of the machine's motor structure, the closed cavity being adapted to receive a preheated preform and allowing the preform within the closed cavity to be blown A preform is expanded to obtain a container, characterized in that the base (4) is wedge-shaped and includes a horizontal closed surface (4a) and a first inclined surface (4b), the horizontal closed surface facing the bottom of the mold (1), and wherein the actuation mechanism (40) of the base (4) includes a wedge element (41b) having a second inclined surface (41c) inclined downward toward the front of the mold (1), the first inclined surface (4b) of the base (4) and the second inclined surface (41c) of the wedge element (41b) are slidably connected to each other.

2. The machine of claim 1, wherein, The actuation mechanism (40) includes: a sliding member (33) having a tubular cavity (61) arranged along a horizontal line located on a vertical plane dividing the two half-molds (2a, 2b); an Archimedes screw (51) having threads and operatively inserted into the tubular cavity (61), wherein the inner surface of the tubular cavity (61) includes a protrusion that engages with the threads of the Archimedes screw (51), such that when the Archimedes screw (51) rotates, the sliding member (33) moves forward or backward according to the direction of rotation of the Archimedes screw (51).

3. The machine of claim 2, wherein, The sliding member (33) is associated with a first slider (34a), which is located above the sliding member (33) and is slidably mounted to a first fixed guide device (35).

4. The machine according to claim 2 or 3, wherein, The bottom of the sliding member (33) is integral with the connecting element (33'), which is then connected to the second sliding member (34b), which is slidably mounted to the corresponding second fixed guide device (35'). The connecting element (33') is associated with the two half molds (2a, 2b) by corresponding connecting rods (36a, 36b), each of which has a first end and a second end.

5. The machine of claim 4, wherein, The first ends of the connecting rods (36a, 36b) are coaxially hinged to the connecting element (33'), while the second ends are hinged between the corresponding side portions (38a, 38b) and the corresponding rear portions (39a, 39b) of the half molds (2a, 2b) at the corresponding engaging elements (70a, 70b), such that when the sliding member (33) is in the forward position, the half molds (2a, 2b) face each other along the corresponding edges (9a, 9b) and the mold (1) is closed; conversely, when the sliding member (33) is in the retracted position, the connecting rods (36a, 36b) act on the hinge points that are hinged to the half molds (2a, 2b), thereby bringing the half molds to the open position.

6. The machine of claim 4, wherein, The second sliding member (34b) is integrally formed with the L-shaped element (41), the L-shaped element including a horizontal portion (41a) facing the front of the mold (1), wherein the horizontal portion (41a) includes the wedge-shaped element (41b) at the front.

7. The machine of claim 1, wherein, The mold (1) includes a support (10) for the mold (1) and a fixed bracket (20), the bracket (20) including a vertical plate (20b) facing the front of the mold (1) and including a guide, on which a third sliding member (34c) associated with the base (4) slides vertically.

8. The machine of claim 7, wherein, The first inclined surface (4b) of the base (4) includes a fourth slider (34d) that slides in a guide formed on the wedge-shaped element (41b).

9. The machine according to claim 1, wherein, The machine or the mold (1) includes a command and control unit configured to manage motion laws for opening / closing a single mold (1), wherein the motion laws are provided for the full opening and / or partial opening of the half molds (2a, 2b).

10. The machine of claim 9, wherein, The command and control unit is configured to manage the overall operation of the machine and perform the following functions: - Read the pressure sensor inside the mold; - Command processing time; - Adjust the parameters of the blowing process; -Actuation alarm signal; - Adjust the heating of the preform; - Adjust the operating speed of the machine.

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