DE8814563U1 - Deep drawing device - Google Patents

Description

Gill-Ann. üassia

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_ 3 - (16 079) Deep drawing device

The innovation concerns a deep-drawing device for deep-drawing plastic films, consisting of a lower mold part and an upper mold part in which a pre-stretching device that can be moved up and down is arranged.

Such deep-drawing devices are well known and do not require any special written proof. In such deep-drawing devices, the plastic film to be deep-drawn is preheated accordingly and inserted in time between the mold upper and lower parts, which are initially open to one another. These are closed after the film web has come to a standstill. After this, the so-called pre-stretcher, which is sealed in the mold upper part, is moved downwards to a certain depth in order to pre-stretch the deformable film. After this, a suitable gas (usually air) is introduced into the mold upper part under pressure. This then applies the pre-stretched film to the walls of the mold cavity in the mold lower part, which is usually cooled, and in this way forms a container of the appropriate shape, more or less deep, from the film web. Since the film is more or less taut against the contact surface of the pre-stretcher head during pre-stretching, i.e. is in frictional contact with it, the stretching in this area of the film is inevitably more or less slowed down, i.e.

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-ltThe film area forming the bottom surface of the cup-like container usually remains thicker than the side wall areas of the container, which can expand unhindered during deep drawing. This is particularly noticeable when processing relatively thick plastic film.

The innovation is therefore based on the task of creating a deep-drawing device with which the cup-like containers to be formed have at least approximately the same wall thickness in the base area as the side walls.

This task is solved with a deep-drawing device of the type mentioned at the beginning according to the innovation by the features stated in the characterizing part of the main claim. Practical embodiments are given in the subclaims.

Pre-stretchers provided with a gas guide channel are known, but such pre-stretchers equipped with a gas guide channel serve to remove sterilization medium (e.g. Dat.pl ;) introduced into the formed cup from the inner bottom area of the formed container in order to be able to achieve perfect sterilization of the bottom area as well. Apart from that, a pre-stretcher designed in this way and known in advance would not be suitable or only ^very little suitable for the present purpose, since the opening of the gas guide channel. ¹ ?

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^Since the gas cushion between the pre-stretching head 2 and the film 15 is essentially only of interest in the pre-stretching phase, the compressed gas required for this can easily be taken via a corresponding valve from the supply line (not shown) to connection ^11J .

As mentioned above, the gas-permeable film contact surface can be made of suitable, porous material 5, but it is also possible to provide the gas-permeable film contact surface 1 with fine holes or fine slots 6 as shown in Fig. 2. The gas-permeable surface 1 is expediently formed from a surface part 8 inserted into a recess 7 of the pre-stretcher head 2. In order to be able to supply the entire gas-permeable surface with gas, a gas distribution chamber 10 is arranged between the outlet 9 of the gas supply channel M and the gas-permeable contact surface 1. In particular when using gas-permeable, porous material, it is also possible, as can be seen from Fig. 3, to insert a correspondingly adapted,

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A suitable fabric, e.g. textile-based, can also be used for the permeable surface.

Claims (1)

-&Lgr;&Pgr;&EEgr;&Kgr; ijH..·. S.J.I * * · ( 16 07 9) S ei hu t. '.yi a ri s &rgr; r ü che : 1. Deep-drawing device for deep-drawing plastic films, consisting of a lower mold part and an upper mold part, in which a pre-stretcher that can be moved up and down is arranged, characterized in that at least a partial area of the film contact surface (1) of the pre-stretcher head (2) is designed to be gas-permeable and the pre-stretcher shaft (3) is provided with a gas supply channel ( ¹⁰ ). 2. Device according to claim 1, characterized in that the gas-permeable film contact surface (1) is formed from porous material (5). 3. Device according to claim 1, characterized in that the gas-permeable film contact surface (1) is provided with fine holes or fine slots (6). H. Device according to one of claims 1 to 3, characterized in that the gas-permeable surface (1) is formed from a surface part (8) inserted into a recess (7) of the pre-stretcher head (2). &kgr;&igr;.. .;!a.ssia 5. Device according to one of claims 1 to 4, characterized in that a gas distribution chamber (10) is arranged between the outlet (9) of the gas supply channel (1) and the gas-permeable contact surface (1).