DE1267412B - Device for producing vessels open on one side, in particular cups, from inflatable thermoplastic material - Google Patents

Description

Device for producing vessels that are open on one side, in particular Cups, Made of Inflatable Thermoplastic The invention relates to a device for producing vessels open on one side, in particular Cups, made of a film made of inflatable, numerous microscopic, consists of finely divided gas bubbles containing thermoplastic material, with a jig for the later forming the edge of the vessel part of the Foil and with a mold and an inner punch that can be pushed into the mold and a The outer ram corresponding to the bottom of the vessel and which can also be inserted, as well as with a Device for trimming the edge of the vessel.

There are already devices of this type for making cups and other similar containers made from very thin, flexible, clear plastic exist, became known. These cups are, for example, a beverage bottle added and thrown away after use.

Other known cups are provided with sealing lids and can be filled with food or other goods.

The known cups have the disadvantage that they once as a result very flexible due to the extremely low wall thickness, d. H. are not very stable and therefore can also be easily damaged. The small wall thickness is with the known Cups, however, are absolutely necessary for those manufactured in very large numbers Cups to achieve the lowest possible cost of materials. In addition, it is disadvantageous that the known cups ensure a low level of thermal insulation, so that this especially when filling very hot or very cold drinks, food, etc. Like. Is very uncomfortable.

In these known devices in each case at least the final deformation of the plastic film made by compressed air as the material the film is incompressible and therefore the walls of the mold and the stamp not exactly matched to a defined, the film receiving mold cavity can be.

It has also been proposed to press-fit vessels manufacture of multi-layer material into a hollow mold using a stamp, however, this vessel material cannot be firmly clamped at the edge, but rather has to it slip during the deformation, so that irregularities with respect to the Amount of material sliding on the circumference arise, unless one Provides a fabric layer in the multilayer material, but not only that cumbersome, but also very time-consuming.

In the invention, a thermo- plastic plastic assumed, which has the special property that after heating it under Pressure in a flowable state, namely within an extruder and after pressure relief, inflates from within, d. H. numerous microscopic and finely divided, forms or contains closed gas bubbles on all sides. Such a plastic has become known, for example, under the trademark »Styrofoam«.

The invention has also been built on the knowledge that by using such a plastic for the manufacture of cups compared to the previously known cups, a considerable saving in material is achieved, whereby the cup is correspondingly light, but still a larger one Wall thickness than the previously known cup is preserved and as a result very stable and is rigid. Another essential aspect is that as a result of the numerous, self-contained on all sides, to a certain extent embedded in the plastic Gas bubbles produce an extremely good thermal insulation.

However, it has now proven particularly difficult to remove the bloated To deform plastic in the desired manner, in particular on cups or Similar containers, which have a relatively thin wall thickness and at the same time to receive certain reinforced parts.

The invention is based on the object of providing a device of to create the type explained at the beginning, which in a particularly simple manner a Deformation of the hot, either coming directly from an extruder or one re-heated inflated plastic film is permitted.

The object is achieved according to the invention in that the Shape and the stamp are designed and coordinated in such a way that they have a defined mold cavity for receiving the vessel educational Part of the inflated film by slightly compressing the film free permit. In this way, there is the advantage that the defined mold cavity enclosing components, i.e. the mold wall and the outer punch or counter punch on the one hand and the forming die or inner die on the other hand still subsequently something can be moved against each other in the sense of compressing the material. This has the advantage that the surface of the cup is smoothed on all sides will.

An advantageous embodiment of the invention is achieved by that the form and the outer die are made of metal and have a coating made of polytetrafluoroethylene and that the inner stamp is made of a material is formed, which has a low thermal conductivity. That way will a too rapid cooling of the deformed cup material avoided and at the same time easy loosening or pushing the cup out of the mold is guaranteed.

In this context, it is particularly advantageous that the inner punch is made of press paper, press board or press linen.

In the drawing, an embodiment of the invention is in the scheme shown, namely shows F i g. 1 shows a side view of an overall system of a Cup molding machine with an upstream extruder, FIG. 2 a horizontal section through part of the system according to section line II-II in F i g. 1, Figure 3 is a partial cross-section according to section line 111-111 in FIG. 1, Fig. 4 shows a detail from FIG. 1 in section and in an enlarged view and FIG. 5 is a view of FIG. 4 according to line V-V.

The left part of the in F i g. 1 shown system is from a Extruder 1 formed, which is equipped with a hopper 2 for the to be processed, plastic, which is described in more detail below, is provided. In itself known Way, the extruder essentially consists of a receptacle for the plastic, which can be heated and pressurized, so that the liquid to pasty Plastic is expediently pressed out at the outlet end 3 by means of a screw will.

A wide nozzle 4 is connected upstream of this end, from which a hot one Plastic film 5 emerges.

The hot film passes from the extruder 1 onto the table 21 of the cup molding machine 1, 2, 4 and 5. The cup forming machine consists essentially of a lower part, which is below the table surface 21 in the one shown in FIG. 1 schematically the housing 22 shown, the usual drive elements and a control device, expediently contains a cam control for the actuation of the entire system. The waste part 23 of the plastic film remaining after the production of the cups, from which according to FIG. 2 two rows of cups each have been formed; will pulled off by take-off rollers 24. Appropriately, the periodically driven Rollers 24 arranged slightly below the table level, so that, as explained later is, the finished cups can be blown over the rollers. The top 25 of the cup molding machine contains the actual shape, which, as below still in connection with FIG. 4 is moved up and down periodically and when cutting out the cup at the edge of the cup in each case by a device 26 can be locked with a locking pin. The locking pin is actuated pneumatically through the compressed air line 27. The upper part is by means of a stand with lateral pillars 28, 29, set up.

In Fig. 4 the actual deformation device is shown in the scheme, which is explained below with simultaneous description of the mode of operation will. First, the hot plastic film 5 in cooperation with the extruder brought onto the table 21 with the rollers 24. Then the movable upper part 25 with the therein against the force of a spring (not shown) by a small amount Dimension in the vertical direction displaceable form 30 lowered downwards. the Form 30 is suitably made of metal and is on its inner surface with a Coating made of polytetrafluoroethylene. The upper part is lowered by means of a double-acting pressure cylinder with piston on a pneumatic Way (not shown). Part of the film, generally a circular area, is between the lower edge 31 of the mold and an outer ring 32 on the one hand and the table surface 21, in particular the upper edge 33 of a sleeve 34 on the other hand clamped and at the same time cooled by heat dissipation so far that a Deformation of this ring part of the film can no longer take place, and thus will a relatively strong cup rim is formed.

Then a forming die which is mounted displaceably within the sleeve 35 pushed upwards into the mold 30, the punch 35 being called the The film part clamped at the edge pushes it in front of it and presses it into the mold 30. The displacement of the forming die 35 takes place pneumatically through the double-sided controllable pressure cylinder 36 with the two compressed air connections 37 and 38. If the forming die 35 is to be moved upwards through the compressed air line 38 air is led into the cylinder, so that the piston located therein is also moves upwards and over the piston rod 39, an arm 40 and the push rod 41 acts on the forming die. The forming die 35 is expedient for reasons the thermal insulation is made of a material that has less good thermal conductivity as metals. The stamp is preferably made of press paper, press board or Press lines formed. However, a metal core can also be provided which is provided with a corresponding surface coating.

The push rod 41 is hollow according to Figure 4 and on the one hand connected to a compressed air connection 42; on the other hand, it is inside the forming die 35 attached, at the end of which there are some outlet openings 43 through which the compressed air can pass through. Through the line 42 is automatic compressed air is supplied by the connected control device at the moment, in which the mechanical deformation process between forming punch 35 and form 30 ends is. The forming die 35 is dimensioned so that between its outer surface and the The inner surface of the mold 30 leaves just as much space as it is occupied by the cup will. The through openings 43 onto the inner surface of the molded cup supplied Compressed air is used to better detach the cup from the forming die, and also to faster cooling of the cup, and eventually it contributes to some compression hardening of the mug.

It is also pointed out here that coaxial to the form 30, namely in the bottom piece, a counter punch 44 is provided which is vertical is held displaceably by means of an axis 45. The underside of the counter stamp 44, which corresponds to the bottom shape of the cup to be formed, is expediently as well as the mold 30, provided with a coating made of polytetrafluoroethylene. When the mold has been lowered in the manner previously described, it lays down the counter punch 44 under its own weight on the middle part of the hot foil on, causing a certain cooling and solidification of the central part of the film enters while the film from the underside through the end face 46 of the forming die is held, which is then just at the level of the table surface 47. While the shape of the counter-punch shifts, constantly in contact with the film, into the mold until it reaches the figure shown in FIG. 4 assumes the position shown. In Fig. 4 this position is only shown to clarify the mold surface, in reality In this position the counter-punch would be in its outermost lower position are located, as indicated by dash-dotted lines.

As soon as, as described above, the cup is shaped is, the further, pneumatically working pressure cylinder 48 is put into action, which by means of a piston rod 49 via knee-shaped articulated levers 50, 51, the the two sleeves 34 arranged next to one another according to FIG. 4 and 5 together shifts a little bit upwards, with the mold 30 also opposite the upper part 25 is moved so that the edge of the cup between the upper edge of the Sleeve 34 and the ring 32 is cut off. So that the upper part 25 is not at the same time is raised, it is previously at the upper end of the rod 52 by the locking device 26, 27 blocked.

It can now after the separation of the upper part 25 again be guided to the top, which is also done by means of a pneumatic cylinder, so that the counter punch 44 at the same time as an exit launcher for the finished cup the form 30 is used.

The cup can then in the direction of arrow 53 (FIG. 1) by means of a blowpipe (not shown) are blown away. The entire previously explained The process is advantageously carried out by means of a cam control known per se 54 controlled, which in cooperation with the upstream extruder and the Transport device for the film all other mechanical movements by pneumatic Cylinder actuated in the right cycle.

Claims (3)

Claims: 1. Device for producing unilaterally open Vessels, especially cups, made of a film made of inflatable, numerous microscopically small, finely divided thermoplastic material containing gas bubbles consists, with a jig for the later forming the edge of the vessel Part of the film and with a mold and an inner punch that can be pushed into the mold and an outer ram that corresponds to the bottom of the vessel and can also be pushed in, as well as with a device for trimming the edge of the vessel, d a d u r c h g e -marked, that the mold (30) and the stamp (35, 44) are designed and matched to one another are that they have a defined mold cavity for receiving the forming the vessel Part of the inflated film with slight compression of the film free permit. 2. Apparatus according to claim 1, characterized in that the shape (30) and the outer die (44) are made of metal and have a coating is made of polytetrafluoroethylene and that the inner punch (35) is made of a material is formed, which has a low thermal conductivity. 3. Apparatus according to claim 2, characterized in that the inner punch (35) is made of press paper, press board or press linen. Considered publications: German utility model no. 1,843,819; French patents nos. 1 219 210, 1843819.