DE102021128341B4 - Method for forming a preform inserted into a mold of a forming and filling station into a container and filling the container being formed with liquid filling material - Google Patents

Abstract

Method for shaping a preform (10) inserted into a mold of a forming and filling station into a container and filling the container that is formed with liquid filling material (11), the preform (10) having its opening (15) in sealed engagement with the Opening of a forming and filling nozzle (14) of the forming and filling station is held and in a first step the preform (10) is filled with filling material, after which in a second step a stretching rod (16) provided in the forming and filling station is removed a waiting position above the preform (10) is moved into the preform (10), characterized in that after the preform (10) has been filled, this and any areas of the filling element (14) that are in fluid communication with it are closed to the outside in such a way that no Filling material (11) can escape and the retraction of the stretching rod (16) leads to an increase in pressure inside the preform, wherein in the second step the stretching rod (16) is moved into the preform (10), displacing filling material and thereby increasing the internal pressure in the preform, and that in a third step, when the stretching rod (16) reaches a defined position within the preform (10), filling material (11) is placed under pressure around the stretching rod (16) and/or through the stretching rod (16) into the preform (10) is initiated.

Description

The invention relates to a forming and filling process according to the preamble of claim 1.

Generic processes are usually carried out in so-called forming and filling machines. Forming and filling machines are intended to replace conventional machines in which a preform is first formed into a container and then the container is filled, i.e. a separate blowing and a separate filling station are provided. In such conventional machines, thermally conditioned preforms placed in external molds are first formed into the finished containers in two temporally and spatially separated steps in the blow molding station by introducing gas under high pressure, and these are then filled in the filling station in a next step.
Forming and filling processes are basically from the DE 10 2014 019 400 A1 and the DE 10 2010 007 541 A1 known. In such processes, thermally conditioned preforms are simultaneously expanded and filled into the desired container shape by introducing liquid filling material under high pressure. During the forming and filling process, as in conventional processes, the preforms are arranged in an outer shape of a forming and filling station, which specifies the final desired container shape by expanding the preform until it rests on the inner contour of the outer form. To the general description of the simultaneous forming and filling process, which can also be referred to as the hydraulic forming process, in the DE 10 2010 007 541 A1 is explicitly referred to, so that further explanations are unnecessary here. As far as forming and filling stations, forming and filling nozzles, forming and filling processes, forming and filling machines or forming and filling processes are discussed below, this always refers to the hydraulic forming of a preform into a container while simultaneously filling the container.

The preforms are made of thermoplastic material, in particular for example PET, and are thermally conditioned in upstream heating devices, for example so-called heating lanes or heating sections, so that subsequent forming into a container is possible. Examples of suitable heating devices are, for example, in WO 2012/083910 A1 described, which shows a conventional blowing machine and conventional blowing processes, namely separate blowing and filling stations. With regard to the thermal conditioning of the preforms, heating devices of conventional blow molding machines can also be used for forming and filling machines with hydraulic forming of the preforms. This document also shows the basic structure of a blow molding station with a multi-part mold that can assume an open and a closed position, and how it can also be used in the present invention, so that no further explanations are given about the shapes of a molding and filling station must, but reference can be made to the descriptions there. This document also shows typical transport and handling devices for the transport of preforms and containers as well as for the handling of preforms and containers as they pass through such a machine, which can also be used in the present invention.

To support the shaping, stretch rods that are usually adjustable in the longitudinal direction are provided in the forming and filling stations and also in conventional blowing stations, which are inserted into the preform during the forming process. The function of these stretching rods is usually to stretch the preform in the axial direction while in contact with it until it reaches the bottom of the closed outer mold. In addition, the stretching rods have a centering function for the preform, so that the preform or the container bubble resulting from it during the forming process is created as symmetrically as possible around the stretching rod and thus around the longitudinal direction of the preform.

The US 2012/0299224 A1 describes a generic method in which, in a first step, the preform is first filled with filling material and then the stretching rod is inserted into the preform. This is intended to displace any air remaining in the preform, for example to avoid a disturbing influence of the air on the filling material to be filled.

The object of the invention is to demonstrate an optimized method for forming a preform into a container while filling it at the same time. Furthermore, a corresponding device for carrying out methods according to the invention is disclosed and technical teachings for operating forming and filling machines are disclosed.

The object of the invention is achieved by a method with the features of claim 1. Further design features of the method according to the invention are the subject of subclaims 2 to 5.

As is also known in the prior art, for example in conventional blow molding processes, but also in molding and filling processes, the preform is with An opening is held in sealed engagement with the opening of a filling element, hereinafter also referred to as a forming and filling nozzle, of the forming and filling station and is filled with filling material in a first step. Since this filling does not have to cause expansion of the preform in the first step, this filling can take place at a low filling pressure, for example at a pressure below a forming pressure, depending on the preform this can be 10 bar or lower. The filling material can also be fed into this first step under a higher pressure, namely with a forming pressure, in order to initiate an expansion of the preform. In such cases, a typical forming pressure can also be above 10 bar and, for example, between 15 bar and 40 bar. In a second step, a stretch rod provided in the forming and filling station is then moved into the preform from a waiting position above the preform.

According to the invention, it is provided that after the preform has been filled, this and any areas of the filling element that are in fluid communication with it are closed to the outside in such a way that no filling material can escape. It is preferred that this area, which is closed to the outside, be completely filled with filling material. It is therefore preferred that the closing to the outside only takes place after sufficient filling material has been supplied to displace air or other gases.

After this filling in the first step, in a second step a stretching rod provided in the forming and filling station is moved into the preform from a waiting position outside the preform, usually above the preform. By retracting the stretching rod, the filling material in the thermally conditioned and therefore deformable preform is displaced in all directions, namely an amount of filling material corresponding to the volume of the immersing stretching rod. Since this area is closed to the outside, no liquid can escape. Retracting the stretch rod leads to an increase in pressure, analogous to retracting a cylinder piston into a cylinder filled with liquid. The preform is the component of the system that is closed to the outside and can offer the least resistance to the increasing internal pressure. As a result, the preform is expanded or stretched bidirectionally in the circumferential direction and in the longitudinal direction as soon as the internal pressure has reached a sufficient level, namely a forming pressure.

According to the invention, part of the pump power otherwise required at the beginning of the forming and filling process, which provides the liquid pressure for the forming, is taken over by retracting the stretching rod.

In the method according to the invention it is further provided that in a third step, when the stretching rod reaches a defined position within the preform, filling material is introduced into the preform under a forming pressure around the stretching rod and/or through the stretching rod. The defined position of the stretching rod at which step 3 should start can, for example, be the position of the stretching rod on the preform tip. The defined position of the stretching rod can, for example, also be a position in which the stretching rod is still at a distance from the top of the stretching rod, for example at a distance of less than 1 cm, preferably less than 0.5 cm, more preferably a few millimeters. In this third step, according to the invention, the flow of filling material is switched on during or after the stretching rod is retracted and the shaping of the preform is started or continued by introducing filling material at volume flows of up to 20 liters/s and pressures of up to 40 bar, if already in the first step an expansion of the preform was initiated.

The term “steps” is to be interpreted broadly in the method according to the invention. Time overlaps, in particular, for example, between the first and second steps and/or between the second and third steps, are entirely possible and can be advantageous. For example, it is conceivable that the movement of the stretch rod into the preform begins before the filling of the preform in the first step with a filling material has been completely completed and the closing against the external environment has taken place. It is also conceivable that the third step, namely the supply of filling material under a forming pressure, does not take place with the stretching rod stationary, but with a moving stretching rod. The only important thing is that the desired effects are achieved, ie the retraction of the stretching rod, more precisely the immersion of the stretching rod into the filling material in the preform, should preferably begin when it is ensured that no filling material can escape from the preform and the preform and areas of the filling element communicating with it are preferably vented. Only then does the increasing immersion of the horizontal bar lead to the desired pressure build-up. Starting to immerse the stretch rod before the area has been closed to the outside reduces this effect, although a small time overlap can be advantageous in order to shorten the overall process time. The filling material flow should preferably be switched on in the third step at the latest when the stretching rod no longer causes any further displacement of filling material in the preform. Here, too, the connection can also take place if the displacement of filling material by the stretching rod has not yet been completely completed. This can also be done with a view A shortening of the process time can be advantageous, because in this third step the expansion of the preform can generally take place at a greater speed than in the second step.

It is preferably provided that the preform and any areas of the filling element that are in fluid communication with it are vented in the first step after or during filling and before retracting the stretching rod, preferably until all gas volumes have been completely displaced, so that the preform and areas of the Filling element is completely filled with filling material. In this way it is ensured that no more compressible gas components are contained in the preform, for example, which would be disadvantageous for the build-up of pressure in the preform.

Filling and venting are usually carried out, for example, via separate valves provided in the forming and filling station, which are closed again after filling and venting so that no filling material can leave the preform.

The EP 2 272 652 A2 describes a non-generic conventional blowing process in which, in addition to a stretching rod, a piston coaxially surrounding the stretching rod can be moved into the preform during the blowing process. The air supply through the blowing nozzle and the movement of the piston can be controlled in such a way that the piston compresses the blown air in the preform, which contributes to increasing the blowing pressure. In this way, blown air can be saved. However, the conditions in forming and filling machines are significantly different than in conventional blow molding stations. In addition, in the known method, it is not the stretch rod that is used, but rather an additional piston for displacement or compression.

There are a number of ways in which the method according to the invention can be designed up to the finished forming and filling of the container.

In one embodiment, for example, it can be provided that the stretching rod is retracted into the preform to such an extent that it comes into contact with the tip of the preform and then stretches it as the stretching rod is retracted further until it reaches the bottom of the outer mold. This stretching process can begin before or after the filling material flow is switched on.

As a rule, in this configuration, the filling material is filled into the preform around the stretching rod, for example. In this case, the horizontal bar could be solid, i.e. H. There are no channels to be provided within the horizontal bar. However, as explained in more detail in the following embodiments, it is also conceivable that the stretch rod is hollow and filling material is introduced into the preform through it. In this case, hollow means that at least one channel is formed within the stretching rod.

An advantageous embodiment in this context provides that the stretching rod is retracted until directly in front of the tip of the preform and then a stream of filling material running through the stretching rod, possibly in addition to a stream of filling material running around the stretching rod, is switched on. Through outlet openings at the end of the stretching rod on the preform side, defined, directed jets of filling material can be generated, which center the preform around the stretching rod and thus also in the mold, without contact between the stretching rod and the preform being absolutely necessary. The required direction and strength of the product jets can be determined empirically. It is conceivable, for example, that lateral openings are provided in the tip area of the stretching rod, from which lateral jets of filling material emerge in the direction of the preform. The openings and the filling material jets should be arranged symmetrically around the longitudinal axis of the stretch rod in order to achieve the desired centering effect. The tip area is defined as the rounded horizontal bar area plus a longitudinal extension of max. 1 or 2 cm.

In a further embodiment, it can be provided that shortly before the stretching rod comes into contact with the tip of the preform, a stream of filling material directed towards the tip is generated, i.e. the stream of filling material is directed in the axial direction of the stretching rod. This jet creates a fluid cushion between the stretching rod and the preform tip, which can remain until the end of the stretching path. In other words, in this embodiment the preform is stretched without contact of the stretching rod with the preform tip. The stretching process is primarily achieved by the directed jet while the stretching rod is being retracted. The beam strength and distance of the horizontal bar from the tip can be determined empirically and depend, for example, on the plastic used, wall thickness and the plastic temperature.

This last described embodiment can of course also work with laterally directed filling material jets, which simultaneously center the preform or support centering, so that both functions of a stretch rod are realized by filling material jets.

The main advantage of at least the last-mentioned embodiment is that the preform can be stretched without direct contact between the tip and the stretching rod.

Also disclosed is a device which is controlled and designed in such a way that methods according to the invention can be carried out with it. Also disclosed is the use of a device for forming a preform inserted into a mold of a forming and filling station into a container and filling the forming container with liquid filling material for carrying out one of the methods according to the invention.

• 1 den ersten Schritt eines erfindungsgemäßen Verfahrens,
• 2 den zweiten Schritt eines erfindungsgemäßen Verfahrens und
• 3 weitere Schritte und Ausgestaltungen des Verfahrens.

The invention will be further described below using several illustrations. This shows:

• 1 the first step of a method according to the invention,
• 2 the second step of a method according to the invention and
• 3 further steps and configurations of the procedure.

The 1-3 show a schematic representation of process steps according to the invention, with the preform 10 being shown without the surrounding shape, against the inner contour of which the preform is expanded, to simplify the drawing. Other elements of a typical forming and filling station are only shown in these figures to the extent that they contribute to the understanding of the process. The forming and filling nozzle 14 is shown very schematically only by its sealing area that comes into contact with the preform. Since both the external shape and the forming and filling station are not essential to the invention in their specific configurations, their graphic representation and explanation are not necessary.

In 1 a preform 10 is shown, into which filling material 11 is filled in the state shown, shown by arrows 12 and 13. The filling takes place via a forming and filling nozzle 14 of a forming and filling station, not shown. The forming and filling nozzle 14 is sealed against a mouth edge 15 of the preform 10. For this purpose, the filling nozzle 14 has an annular seal 25 made of an elastic material.

The preform 10 is further accommodated in an outer shape, not shown, of the forming and filling station, which specifies the desired final container shape through its inner contour. Above the mouth edge 15 of the preform 10 you can see the lower end of a stretching rod 16 in the forming and filling nozzle 14. The stretching rod position shown can be, for example, its required waiting position.

In the in 1 In the first step of a method according to the invention shown, the preform 10 is filled with filling material 11, preferably with simultaneous venting. For this purpose, a valve (not shown) controlling the inflow of the filling material (11) is opened. For the preferably simultaneous venting, a venting valve (both not shown) controlling a venting line is also opened.

After the filling and preferably also the venting has been completed, the stretching rod 16 is moved into the preform 10. In the exemplary embodiment shown, the preform is completely filled and preferably completely vented and closed to the outside, so that no filling material can be displaced out of the preform 10, as indicated by the symbol 17. In the in 2 In the situation shown, the stretch rod may have reached its defined position according to the claim or may still be on the way to this defined position, for example if this defined position according to the claim is the contact position on the preform tip.

The insertion of the stretch rod 16 into the filled preform 10 leads to a displacement of the filling material 11 contained in the preform. Since this area is closed to the outside, this displacement leads to an undirected increase in pressure, which in turn is as shown in the drawing in 2 an expansion of the preform 10 in all directions. This is indicated by the arrows 18 and 19, which represent an expansion of the preform 10 in a bidirectional direction, and by arrows 20, which are intended to show an expansion in the longitudinal direction. The insertion of the stretching rod into the filled preform while at the same time closing this area against the external environment leads to the beginning of the forming of the preform because the pressure that builds up as a result has reached the level of a forming pressure. During this forming step, no further inflow of filling material has to take place, but a further inflow of filling material can begin before the stretching rod has displaced the maximum displaceable amount of filling material and has therefore reached its maximum possible displacement effect.

When the stretch rod 16 has reached a defined position in the preform 10, the flow of filling material is switched on as in 3 indicated by arrows 12 and 13. In the exemplary embodiment shown, the in 2 shown position of the horizontal bar 16 is the defined position as claimed. In alternative embodiments, this defined position can also be achieved be as soon as the stretch rod 16 rests on the preform tip.

In the case shown, the flow of filling material is guided both around the stretching rod 16 and through the stretching rod 16 into the preform 10. This has the advantage that a large inflow cross section is available and a large amount of filling material can therefore be supplied in a short time. The filling material 11 emerges from the stretch rod 16, among other things, through outlet openings 22, 21 and 23. The filling material 11, each delivered in a directed jet through the side outlet openings 22 and 21, ensures that the preform 10 is and remains centered around the stretching rod and therefore also in the mold. The jet directed through the outlet opening 23 perpendicularly onto the tip of the preform 10 also causes a centering of the preform 10, but also generates a filling material cushion and a stretching force in the lower region of the preform, which, when the stretching rod 16 is retracted further, through the opening 23 emitted beam is shifted accordingly and causes the preform to be stretched without the stretching rod having to rest on the tip of the preform 10.

Modifications of the stretching rod shown can, for example, provide that only the outlet opening 23 is provided in order to direct a jet of filling material with a stretching effect onto the preform tip in the axial direction of the preform. It is also possible that only the side outlet openings 22 and 21 are provided in order to thereby bring about centering of the preform 10, while, for example, the stretching of the preform in the axial direction is carried out by the stretching rod 16 itself, in that it rests on the preform tip and stretches the preform 10 in the direction of the bottom of the outer mold.

Claims (5)

Method for shaping a preform (10) inserted into a mold of a forming and filling station into a container and filling the container that is formed with liquid filling material (11), the preform (10) having its opening (15) in sealed engagement with the Opening of a forming and filling nozzle (14) of the forming and filling station is held and in a first step the preform (10) is filled with filling material, after which in a second step a stretching rod (16) provided in the forming and filling station is removed a waiting position above the preform (10) is moved into the preform (10), characterized in that after the preform (10) has been filled, this and any areas of the filling element (14) that are in fluid communication with it are closed to the outside in such a way that no Filling material (11) can escape and the retraction of the stretching rod (16) leads to an increase in pressure inside the preform, wherein in the second step the stretching rod (16) is moved into the preform (10), displacing filling material and thereby increasing the internal pressure in the preform, and that in a third step, when the stretching rod (16) reaches a defined position within the preform (10), filling material (11) is placed under pressure around the stretching rod (16) and/or through the stretching rod (16) into the preform (10) is initiated. Procedure according to Claim 1 , characterized in that the preform (10) and any areas of the forming and filling nozzle (14) that are in fluid communication with it are vented after or during the first step of filling and before the second step of retracting the stretching rod (16). Procedure according to Claim 1 or 2 , characterized in that the stretching rod (16) is retracted so far that it touches the tip of the preform (16) and exerts a stretching force until it reaches the bottom of the mold. Procedure according to one of the Claims 1 until 3 , characterized in that during the retraction of the stretching rod (16) and before it touches the tip of the preform (10), a flow of filling material running through the stretching rod (16) is switched on, which is directed via several outlet openings provided in the stretching rod (16). Beams (22, 21, 23) are emitted into the preform (10), the beams (22, 21, 23) being directed so that they keep the preform tip centered around the stretching rod (16) during forming into a container . Procedure according to one of the Claims 1 until 4 , characterized in that during the retraction of the stretching rod (16) and before it touches the tip of the preform (10), a flow of filling material (23) running through the stretching rod (16) and directed towards the tip of the preform (10) is switched on, which a filling material cushion is created that reaches up to the top, which is retained when the stretching rod (16) is retracted further until the bottom of the mold is reached.