DE2011928A1 - Thin walled plastic container prodn by combined injection - moulding and deep drawing - Google Patents

Abstract

Thin walled plastic containers are produced by preforming a molten granulate and heating the preform to the temp. required for deep drawing in an injection mould, moving the lower mould part with the heated preform by a supporting, axially displaceable turntable to a deep drawing position, and pressing the preform in this position against a cooled deep drwing component which is also supported on a turntable. Deep containers and containers with a complicated shape or an esp. thin wall can be easily produced at a low cost.

Description

Process for the production of particularly thin-walled plastic containers The identification relates to a process and a device for the creation of especially thin-walled plastic containers.

The production of plastic containers, in particular cups, takes place either with deep-drawing or injection molding machines. With the thermoforming machines Plastic foils inserted into the mold, specially made for the production of cups used. The injection molding machines, on the other hand, are used to manufacture plastic cups the actually cheaper raw material, namely granules, which are in a molten state is injected directly into the injection mold, that is, without prior processing. It follows that the production of plastic cups with a Deep-drawing machine is less economical than an injection molding machine.

The deep-drawing machines, however, are left with the manufacture of those Reserved plastic cups that have particular difficulties with injection molding machines prepares what is the case if it is particularly thin or particularly large Mug is only made with relatively expensive injection molds can be. So cups can only be injected with one wall thickness, for example four times as much is required A deep-drawn cup, on the other hand, can be ol-ne further with the desired thin wall thickness can be produced, i.e. it has only a quarter of the actual weight of raw material than the molded cup. Because it However, exceptionally large quantities are involved in the production of cups, ~ the weight of the raw material plays an important role in the pricing of the cups. In this respect, the deep-drawing machine is the same as the opposite. the injection molding machine more advantageous.

However, it should also be noted that it is special for pulling deep cups and complex container shapes still additional expenses for The thermoforming machine is needed to achieve the distribution of thicknesses in the same way as one would like to have them.

It should also be mentioned that the packaging industry is economic en reasons who want to manufacture plastic containers themselves, especially in connection with . the packaging machines with which the containers are filled and sealed will. : it is not without further ado with the previous production machines possible.

The invention is based on the idea of taking advantage of the thermoforming machines and the injection molding machines, bypassing the disadvantages of these two machines to make them usable in a combined injection molding-deep-drawing arrangement.

In the method according to the invention, this is achieved in that an injection mold merely pre-forms the supplied molten granulate and a temperature suitable for deep-drawing the preform by heating achieved, and that the lower mold part it dtn warm preform through one of these supporting, for example axially displaceable turntable in a position for the deep drawing of the preform arrives and there against a search for example attached to a turntable and cooled n deep-drawn upper part is pressed.

The lower part of the mold can be used for easy opening of the injection mold and secure sticking of the preform on the lower part of the mold to a slightly higher level Temperature than the mold top are heated, what by vacuum bar. Compressed air can be supported on the opposite sides.

In a device for carrying out the method are an injection molded upper part stationary on the injection molding machine and at least two injection molded lower parts or at least two deep-drawn upper parts on the rotary discs of the injection-molded deep-drawn assembly attached. To increase the working speed, the turntable can be deep-drawn have any number of deep-drawn tops.

The injection mold can also be designed in such a way that through it only one disc but with different wall thicknesses especially for the Manufacture of cups with reinforced bottom and reinforced cup rim injection molded will. For the production of bottle-shaped and similar containers are known in US Divide the shapes lengthways.

An exemplary embodiment of the invention is shown schematically in the drawing shown.

An injection mold of the injection molding deep-drawing arrangement consists of one Upper mold part 2 and a lower mold part 3. The upper mold part 2 is on the injection molding machine Stationarily attached, of which only the injection molding cylinder 1 is shown is.

The lower mold part 3 is also axially on the upper front side displaceable three-disc 4 arranged. There are at least two on the turntable 4 this mold lower parts are provided, of which, as can be seen from the drawing, the The second lower mold part 5 is located in the deep-drawn area 6 and with the deep-drawn upper part 7 is connected.

The deep-drawn upper part 7 is on the lower face of another Rotary disk 8 attached. On the threshing disc 8 there is at least one more Deep-drawn upper part 9, which lies in the ejection area 10 '.

The molded parts 3, 5, 7, 9 of the injection-molded Tifziehordnung still have Channels 10, 11, 12 formed in a known manner, which are in the injection molding and Tifziehstellung with a compressed air or. Vacuum line are connected. the injection mold is also designed in such a way that the injection-molded preform 13 has a stronger one on the bottom and on the belt part Has wall thickness than on its other parts.

To make a cup, the piston of the injection molding cylinder presses 1 in a conventional manner melted granules into the injection mold 2,3, which are not cooled, but heated. This heating is set so that the lower part of the mold 3 receives a temperature that still requires deep drawing of the preform 13 by means of compressed air and vacuum or just one of these two media.

The material experiences a cooling from plastic to thermo-elastic Area. The injection mold 2, 3 is advantageously heated electrically Ways.

After the injection molding of the preform 13, the turntable 4 becomes axial displaced so that the lower mold part 3 is separated from the upper mold part 2. Of the The lower mold part 3 is now brought into the deep-drawn position 6 by the turntable 4.

In position 6, the turntable is moved axially 4 in the opposite direction than before the lower mold part 5 to the deep-drawn upper part 7 of the turntable 8 is pressed, whereupon a nozzle 14 provided in the channel 10 opens will. At the same time, the cooled deep-drawn upper part 7 via its channel 12 with it connected to the vacuum line. The warm preform 13 is then on the one hand through the compressed air, or on the other hand, deep-drawn by the vacuum in the deep-drawn upper part 7. The cooling of the deep-drawn upper part 7 causes the molding to solidify quickly 13 guaranteed.

After completion of the deep-drawing process, the turntable 4 is again axially vrschober-. The lower mold part 5 is then removed from the upper mold part 7. The windshield 8 then brings the cooled upper mold part 7 out of the area the deep-drawn position 6 in an ejection position 10, in which by supplying compressed air The cooled molding 15 is ejected into the deep-drawing foria 5.7.

It can of course increase the working speed and for a continuous production process of the cup, several lower mold parts 5 and mold upper parts 7 as shown in the drawing on the turntable 4 or 8 are provided.- Before everything, the rotary disk 8 karsn any number of Carry deep-drawn upper parts 7, so that the cups 15 the multiple cycle time of the injection-molded deep-drawn arrangement is available for cooling.

Since no significant cooling is required in the first step is, the output or the number of cycles is determined by the liquefaction performance of the injection molding machine and the number of deep-drawn upper parts 7 is determined. With sufficient condensing capacity The number of cycles of the machine arrangement corresponds to the injection molding machine Ratio, cooling time of the moldings 15 Number of deep-drawn upper parts 7 In addition can also multiply the performance of the machine through multiple tools in each station will. Adaptation to real needs is therefore possible within very wide limits.

A major advantage of this injection-molded deep-drawn arrangement is now In particular, it can be seen in the fact that instead of a specially manufactured flat semi-finished film product with a uniform wall thickness, the much cheaper granulate passes through the direct use for the production of plastic containers in an economical way Respect is extremely cheap.

Furthermore, the cups can be attached to the injection mold by means of a corresponding shape bond can be produced with different thicknesses at any point, whereby the preform can be positive as well as negative and to simplify tooling #### can only be produced as a simple shingle.

Furthermore, no punched edge falls during the manufacture of the plastic cups or ridge. In addition, the edge design of the preform by the formation of the injection mold in every way so gestelten that, for example the mouth roll of a drinking cup does not require additional work.

Another advantage of the injection deep drawing process is that the Drawing depths, i.e. the ratio of the drawing depth to the diameter of the molding, is practical unlimited it, so you can get not only simple cups but also bottle-like ones Can produce containers economically.

The new manufacturing process is also a more economical use of energy than possible with the previous method, since the heat of the preform to be injected is used for shaping and no intermediate cooling takes place.

With this manufacturing process, there is also the possibility of to make even the smallest production units profitable, so that the packaging Industry, even with limited sales, no longer dependent on sub-suppliers and can design their own containers individually. This also works has a positive effect on storage. The process is therefore compared to the conventional one Process a great simplification of the, woderen also the amortization of the arrangement Significantly suffered @@ rtert is allowed @ e.

Claims (7)

Claims Process for the production of particularly thin-walled plastic containers, characterized in that an injection mold (2,3) feeds the molten granulate only preformed and by heating a deep drawing of the preform (13) reached suitable temperature, and that the woraint part (3) with the warm Preform by a turntable that supports it, for example axially displaceable (4) in a position (6) for deep drawing of the preform and there against an example of a cloth on a turntable (8) attached and cooled deep-drawn part (7) is pressed 9. The method according to claim 1, characterized in that the Mold lower part for easy opening of the injection mold and safe sticking of the preform on the lower part of the mold to a slightly higher temperature, the upper part of the mold is heated. 3. The method nac 'claim 2, characterized in that the light Opening of the injection mold and the safe sticking of the preform on the mold by vacuum or. Compressed air is supported on the opposite sides. 4. Device for performing the method according to claim 1, characterized marked that the injection mold, -ssobertel is stationary on the injection molding machine and at least two springuss lower parts or at least two deep-drawn upper parts on the turntables of the injection-molded deep-drawn arrangement are attached. 5. Device according to claim A, characterized in that the Turntable of the deep-drawing assembly to increase the Arbeitsgeschwin speed a Has any number of deep-drawn tops. 6. Device according to claim 4, characterized in that the injection mold is designed such that only one disc of different Wall thickness, for example for the production of cups with a reinforced bottom and reinforced cup wall is injected. 7. Device for the production of bottle-shaped containers according to Claim 6, characterized in that the molds are divided longitudinally in a known manner are.