DE102013010207A1 - A method for producing containers filled with a liquid product from preforms made of a thermoplastic material - Google Patents

Abstract

The present invention relates to a method for producing containers filled with a liquid filling material from preforms made of a thermoplastic material. The object of the invention is to present a method for the controlled and / or controlled reshaping of a preform into a container in which contamination of the outside of the container or of the filling machine by splashed contents from the stretching rod is avoided. To achieve the object, a method for producing containers filled with a liquid filling material 8 from preforms 1 made of a thermoplastic material is proposed, the respective preform being at least thermally conditioned and then during a forming phase in a mold 4 by liquid introduced into the preform under pressure Filling material is reshaped with axial and radial stretching into the container, which is characterized in that the axial stretching is initiated by the filling material supplied to the preform in pulses.

Description

The present invention relates to a method for producing containers filled with a liquid product from preforms made of a thermoplastic material.

Methods are known from the prior art in which a container, in particular a bottle, is produced from a plastic preform. For this purpose, the blank is at least thermally conditioned and then deformed during a forming phase in a mold by a liquid to be introduced into the preform liquid pressure medium hydraulically under axial and radial stretching in the container.

In most known methods, a so-called stretching rod is used for the axial stretching, which is introduced into the preform through the mouth of the preform, which later represents the container opening. With the stretching rod, a mechanical force is exerted on the bottom of the preform so that the thermally conditioned preform is axially stretched. The greatest force is required to initiate the stretching process. It is important to steer the axial stretching in a controlled manner so that the future container forms uniformly and the wall thickness reaches the desired values.

However, the use of a stretch rod in the hydraulic molding with liquid filling material has the disadvantage that the stretching rod must be immersed in the medium and always remains on removal bar from the filled container contents on the stretching bar, which can contaminate the filling machine or the container outer sides. Especially with sugary liquids or the partial container filling with syrup, this leads to contamination that must be avoided.

From the DE 10 2011 015 666 A1 For example, a method is known in which a guiding and shaping device acts on the preform during the extension from the outside. It is difficult to transfer the tensile forces required to initiate the stretching on the preform, so that these forces must be applied primarily from the inside by pressure of the inflowing medium. But it can not be differentiated between axially and radially acting force, so that the initiation of the axial stretching is problematic.

The object of the invention is to provide a method for controlled and / or controlled forming of a preform in a container, in which contamination of the container outside or the filling machine is avoided by spilled product from the stretching rod.

To solve the problem, a method for producing filled with a liquid product containers of preforms made of a thermoplastic material is proposed, wherein the respective preform at least thermally conditioned and then during a Umformphase in a form by under pressure in the preform introduced liquid contents under axial and radial stretching is transformed into the container, which is characterized in that the axial extension is introduced by the preform pulsed filling material.

According to the invention, the liquid medium is fed in pulses to a thermally preconditioned preform, so that the axial stretching process is initiated. Pulse-like feeding of the pressure medium is understood to mean a feed which takes place directly into the empty preform and whose jet diameter and feed speed are suitable for imparting an impulse upon impact with the preform and thus triggering the drawing process.

The feeding of the filling material preferably takes place in the axial direction of the preform, so that the full impulse of the filling material jet impinging in the preform is available for the axial stretching.

The diameter and velocity of the product jet depend on the force required to initiate the stretching of the preform and thus depend on the material used, the geometry of the preform and also the thermal conditioning.

When using a stretch rod according to the prior art are usual stretching forces between 400 N and 600 N. In order to achieve comparable values between 350 N and 650 N with a Füllgutstrahl, the beam diameter between 3 and 20 mm and the flow rate between 30 and 100 must m / s lie. The exact values also depend on the product used.

The feed rate can be changed during the filling and molding process. In particular, the filling and molding process can be started at a high feed rate to achieve a large impulse for the initiation of the stretching operation. During the filling and molding process, the feed rate can then be reduced to allow controlled axial and radial shaping of the container. Likewise, the jet diameter of the medium in the course the filling and molding process changed, in particular reduced.

The axial extension of the preform can be guided by a guide device acting from outside on the preform. The guide device may in particular partially enclose the preform or be gripping on the preform. The axial stretching process can thereby be controlled and the pressure of the inflowing into the preform filling material for the axial or radial stretching can be used. For this purpose, the axial stretching speed of the preform can be limited at least temporarily.

It is conceivable z. B. a process sequence in which transmitted by the pulsed inflowing medium, a high initial pulse to the preform and the stretching process is triggered. After a first axial stretch, the guide means limits the rate of axial stretching and simultaneously guides the forming preform to ensure symmetrical formation of the container. The pressure of the inflowing material in the preform can then be converted more or less strongly into the radial extension, depending on the degree of limitation of the axial extension.

Conversely, a support of the axial extension by the guide device is possible. For this purpose, the guide device is preferably arranged cross on the preform and can transmit tensile forces in the axial direction of the preform.

An embodiment of the invention will be explained in more detail below with reference to the accompanying drawings, which show the following:

1 shows a preform in a mold;

2 shows a preform in the phase of initiation of stretching by a pulse jet;

3 shows a container forming from a preform.

In 1 is a preform 1 pictured over an estuary 2 and a rotationally symmetrical body 3 features. The preform 1 is in a form 4 , In a filling machine, not shown, the preform 1 hydraulically formed by introducing a liquid filling material and filled at the same time.

This is done on the muzzle 2 of the preform 1 the filling head 5 a filling machine sealingly attached. The filling head 5 is with a supply line 6 provided for the liquid contents by a throttle valve 7 can be opened and closed.

The molding and filling of the container is then, as in 2 represented by a pulse jet of the medium 8th initiated. The contents 8th gets into the preform at high speed 1 initiated. This will be the preform 1 axially stretched. By further inflowing contents 8th the formation of the container takes place within the mold 4 ,

When using conventional preforms, a force of 400-600 N is required to initiate stretching. In the illustrated embodiment is as a filling 8th Water used. The jet exerts a stretching force on the bottom of the preform, which depends on the mass and velocity of the jet. The mass of the beam can be influenced by the diameter. The applied stretching force can thus be controlled via the beam diameter and the jet velocity. For a jet with a diameter of 10 mm, a stretching force of 385 N results at a jet velocity of 70 m / s and of 635 N at 90 m / s according to the formula: F = density × beam cross section × feed rate ²

In the in 2 The process phase shown has the preform 1 experience a first both axial and radial extension.

In 3 is the shaping of the container 9 more advanced. The axial and radial stretching is carried out hydraulically by pressure effect of the supplied under pressure filling 8th , where the container 9 expands with increasing filling degree in the circumference. During the filling process, the feed rate of the medium can be changed and in particular reduced.

QUOTES INCLUDE IN THE DESCRIPTION

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Cited patent literature

• DE 102011015666 A1 [0005]

Claims (11)

Method for producing liquid goods ( 8th ) filled containers of preforms ( 1 ) of a thermoplastic material, wherein the respective preform ( 1 ) at least thermally conditioned and then during a forming phase in a mold ( 4 ) by being pressurized into the preform ( 1 ) introduced liquid product ( 8th ) is deformed under axial and radial stretching into the container, characterized in that the axial extension through the preform ( 1 ) Pulsed fed ( 8th ) is initiated. Method according to claim 1, characterized in that the filling material ( 8th ) in the axial direction of the preform ( 1 ) is supplied. Method according to claim 1 or 2, characterized in that the filling material ( 8th ) the preform ( 1 ) is fed at high speed, preferably at 30 to 100 m / s, in particular at 70 to 90 m / s. Method according to one of claims 1 to 3, characterized in that the filling material ( 8th ) is supplied with a beam diameter of 3 to 20 mm, preferably from 5 to 14 mm and in particular of 10 mm. Method according to one of claims 1 to 4, characterized in that in the preform ( 1 ) pulsed impinging ( 8th ) exerts a force of from 350 to 650 N, preferably from 400 to 600 N. Method according to one of claims 1 to 5, characterized in that the feed rate of the filling material ( 8th ) is changed during the filling and molding process. A method according to claim 6, characterized in that the feed rate of the medium ( 8th ) is reduced during the filling and molding process. Method according to one of claims 1 to 7, characterized in that the beam diameter of the medium ( 8th ) is changed during the filling and molding process. Method according to one of claims 1 to 8, characterized in that the axial extension at least temporarily by a from the outside of the preform ( 1 ) attacking leadership institution is performed. A method according to claim 9, characterized in that the guide means the preform ( 1 ) is partially enclosing or cross-gripping arranged on the preform. A method according to claim 9 or 10, characterized in that the guide means limits the axial stretching speed at least temporarily.

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