DE2056719C3 - Method for producing hollow bodies from thermoplastic material with an additional opening - Google Patents

Description

35

The invention relates to a method / to manufacture hollow bodies from thermoplastic Plastic with an additional opening next to the one created by blowing during the expansion process Opening in the wall of the hollow body, piercing the still plastic wall of the emerging Hollow body.

In addition to the opening created by the blow molding process when producing hollow bodies further openings are often necessary. /. B. a filling and a ventilation opening (DE-GM 19 00 553).

It is known to make such openings, for example, by inserting core parts during the blowing process to produce (DE-GM 19 97 091). This requires one relatively large effort, especially with simpler training of the openings is not justified.

It is also known to start with blow molding to extrude a tube and then to close it by squeezing both ends, whereupon a Blowing needle is passed through the still plastic material, through which the blown air then enters the otherwise closed Cavity is introduced (FR-PS 14 05 298 and 14 75 911). But this process serves not for making additional openings.

It is also known to attach to openings of Höhlkör pern to make a thickening of the wall (DE-PS 8 33 620 and US ^ PS 28 i 9 573).

Maii can after the blowing process and after the er * cold the thermoplastic material produce additional openings by drilling or the like, the The disadvantage arises that drilling chips can get into the interior of the container. Removing the drilling chips is sometimes difficult, but in any case time-consuming. Furthermore, after the actual blowing process, there is another Operation required.

The invention aims to overcome the aforementioned disadvantages.

This object is achieved according to the invention in a method of the type mentioned at the outset solved that the odv.r during the blowing process in the immediate Subsequently, part of the material removed from the additional opening by means of the blow needle the wall is at least partially pressed into the blow needle as a result of the guidance of the blow needle, and then that move this material by means of gas pressure to the inside of the hollow body with permanent adhesion there! will. It is thereby achieved that all for further use in a simple manner in one operation The necessary openings of the hollow body can be produced without the need for special core parts and the like and without drilling chips and the like being able to occur.

In one embodiment of the method according to the invention, the material is on the opposite The inside of the hollow body is thrown. It was found that hollow bodies produced in this way did not lead to any The material introduced in this way is prone to damage.

According to another embodiment of the invention, the material is in the immediate vicinity the blow needle pressed onto the inside of the hollow body.

The invention is explained below with reference to the drawing. It shows

F i g. I a section from a hollow body produced according to the invention.

F i g. 2 and 3 training of suitable blown needles.

In the case of the hollow body according to FIG. 1 can be /. B. around the fuel tank of a motor vehicle or an agricultural auxiliary device. The hollow body is first produced in a known manner by blowing, and at the same time a filling liquid is attached to the wall 1 2 is molded. The filler neck 2 represents a reinforcement of the material leads. This has the consequence that within this Maierialverslärkung. namely within the still as Solid material of the existing nozzle, the plastic something remains in the plastic state longer. The blow needle can now through this plastic plastic compound are performed, the material at least partially penetrating the blow needle. If you now the blow needle is subjected to a gas pressure, then the penetrated material is again out of the Blow needle removed, after which the blow needle backgc / o and the process is complete.

F 1 g. 2 shows a blow needle 3. which is especially for one such blowing process is suitable. It is a matter of a tubular body with a beveled spil / c. When inserting the blow needle 3 through the Emfüllstui zen 2 according to F 1 g. I practically all of the displaced material is taken up into the hollow space of the blow needle took. Then the gas pressure is suddenly applied to the blow needle 3 and hurls it plastic material on the opposite wall, where it sticks to the inside of the hollow body. The hollow body is expediently blown with Slütz air, which ensures that the wall can break through is prevented. The blown material

welds to the container wall, which causes the so-made. Container no chips or other stray material.

Fig.3 shows another blow needle 4, the one in front represents closed hollow body, the mil several holes distributed around the circumference 5 for the exit of the blown air is provided. For example, there may be 6 or 8 holes 5 evenly distributed around the circumference. The arrows 6 indicate the auxiritis opening of the blown air.

With the help of the blow needle 4 shown in FIG the filler neck 2, which is still in the plastic state, is also shown in FIG. I pierce, being the displaced material is partially pushed in front of the blow needle 4, partially adheres to its wall and partially penetrates into the holes 5. After the blow needle 4 has passed into the interior of the container

the gas is blown off, the backward-facing Gas jets the material removed from the filler neck 2 in the immediate vicinity of the blow needle 4 press it against the wall. This also provides a desired reinforcement of the container wall in the Proximity of the filler port 2 created.

If the container wall is sufficiently thick, the method can be carried out practically at any point on a hollow body produced in this way. If, on the other hand, thin-walled hollow bodies are to be produced, then a reinforcement of the wall thickness is expediently provided at the point at which the opening is to be made, expediently as in the exemplary embodiment according to FIG. 1 a reinforcement in the form of a filler neck Z.

1 sheet of drawings

Claims (5)

Patent claims: 1. Process for the production of hollow bodies Made of thermoplastic with an additional opening next to the one during the expansion process opening created by the blowing in the wall of the hollow body, piercing the still plastic wall of the resulting hollow body, characterized in that the during the blowing process or in the immediate Subsequently, part of the material removed from the additional opening by means of the blowing needle (3, 4) the wall (I) is at least partially pressed into the blowing needle (3, 4) as a result of the blowing needle being guided> 5 and that then this material by means of gas pressure on the inside of the hollow body with a permanent there Liability is moved. 2. The method according to claim 1, characterized in that the material is ^{thrown onto the opposite inner space r} <e of the hollow body. 3. The method according to claim I. characterized in that that the material in the immediate vicinity of the blow needle (4) on the inside of the Hollow body is pressed. 4. The method according to claim I. characterized in that that at the point where the additional opening is made, a reinforcement of the Wall thickness of the hollow body is made 5. The method according to claim 4, characterized in that that the reinforcement is designed in the form of a connecting piece (2).