DE878105C - Method and device for blowing seamless, bottle-shaped hollow bodies made of plastic - Google Patents

Description

Method and device for blowing seamless, bottle-shaped Hollow bodies made of plastic There are processes for blowing seamless hollow bodies made of plastic, in which, as shown in Fig. I, in conventional injection molding machines Manufactured plastic body (preform) 1 in a thermoplastic state in a Hollow form 2 are hung and inflated.

Then methods have become known in which from an annular, valve-like opening plastic is pressed out and inflated. The ring-shaped, valve-like opening (Fig. 2), from which the plastic 3 is pressed, is thereby of a housing 4 and a valve piston adjustable with respect to the housing or Valve stamp 5 formed. The air for inflating the resulting hollow body 6 is fed through a bore 7 in the valve stem 5.

It has been shown - and this is where the invention comes in - that one compared to this process, a technical advance is achieved if you know how shown in Fig. 3, made up of valve-like annular openings provided by a housing 4 and an adjustable valve piston 5 are formed, plastic 3 is pressed out, but housing 4 and valve stem 5 not in the same direction, from the annular As seen from the outlet opening (as is the case in Fig. 2), but in the opposite direction as shown in Fig. 3.

For example, the following facility is used for this purpose: On the valve stem 5 in Fig. 4, which has a hole 7 for the supply of the blown air carries, a movable slider 8 is attached to this valve stem and against the valve stem 5 with a seal, for example a stuffing box 9, closed.

Between the housing 4 and the slider 8 is a shared Form 10 attached. After closing the mold 10, plastic 3 is in the of the slider 8, the housing 4, the mold 10 and the valve stem 5 are formed Injected cavity.

Then, as shown in Fig. 5, the sliding piece 8 and the shape 10 on the one hand and the housing 4 with the valve piston 5 on the other hand from each other removed, at the same time from the housing 4 plastic 3 pressed out and through the hole 7 air is blown. The sequence of the manufacturing process for a Hollow body first gives that in Fig. 5 and finally that in Fig. 6 or 7 schematically shown picture. The valve stem 5 and the housing 4 are also against each other movable. But they change their position to one another during the blowing process only as far as the exit cross-section through which the plastic 3 is removed from the housing 4 exits, should be changed.

As shown in Figs. 6 and 7, it is caused by blowing in air in the hole 7 forming hollow body 11 is during the entire manufacturing process both on the opening side (bottle neck 12 in Fig. 6) and on the opposite side Side (bottle bottom I3 in Fig. 6). This has the advantage that the hollow body in the event of inequalities within the material, it is less easy to become asymmetrical, than is the case with the previously known methods, in which only one end of this resulting hollow body, as for example in Figs. I and 2 is held during the manufacturing process. With the latter The hollow body, as Fig. 1 shows particularly clearly, can process within "Dodge" the hollow form 2 to the side, resulting in unequal wall thicknesses of the finished Hollow body leads.

The fact that the resulting hollow body II, in Fig. 6 and 7, held during the manufacturing process at both ends 12, I3 (in Fig. 6) is, gives the possibility of the resulting hollow body during inflation to pull apart or stretch in the longitudinal direction. The stretching in two directions which the wall of each hollow body experiences during inflation, can therefore in the case of the present one Process can be reinforced by an additional stretching in the longitudinal direction. It will be discussed later that this is particularly important in the processing of some plastics Meaning is.

For influencing the manufacturing process of the resulting Hollow body is one with the stretching of the resulting plastic body additional, previously unknown possibility, so that the manufacturing process of a hollow body overall by the following factors or the way in which they are changed and coordinated during the manufacturing process, the following is determined: a) the size of the annular outlet cross-section for the plastic 3, which is determined by the respective distance between housing 4 and valve stem 5, in Fig. 3 to 7, as well as housing 14 and valve stem 5 in Figs. 8 and 9, is determined, b) the speed at which the plastic 3 is pressed out of the housing 4 becomes, c) the speed with which in Figs. 4 to 7 slider 8 and shape 10 on the one hand and housing 4 with valve plunger 5 on the other hand as well as in Fig. 8 and 9 slider 8 and shape 2 on the one hand and housing 14 and valve stem 5 on the other hand be separated from each other, d. H. the extent to which the resulting plastic body is pulled apart or stretched in the longitudinal direction, d) the amount or the Pressure generated by channel 7 in Figs. 4 to 7 or channel 15 in Figs. 8 and II injected air.

In addition, there are of course other influencing factors the properties of the plastic to be processed, the choice of processing temperatures as well as the dimensions of the manufacturing facility, however, in the present In connection with this, the latter three points are left out of consideration. By corresponding Changing or coordinating the parameters mentioned under a) to d) during of the process you have it in your hand, both the wall thickness and the shape (slim, spherical or ellipsoidal flattened) the resulting hollow body ii (in Fig. 6 and 7) can be influenced much more extensively than is possible with other methods is. Will -man without using a shape 2, for example a slim, tubular one Hollow body rI erzeilen, because it is shown on the left half of Fig. 7, so you pull slider 8 and form 10 on the one hand as well as housing 4 and valve stem 5 on the other hand relatively quickly apart and at the same time presses plastic 3 out of the housing 4 without supplying too much blown air through the bore 7. Conversely, if an ellipsoidal or spherical hollow body 11, as shown in Fig. 6 plastic is pressed out of the housing 4 and blows the resulting hollow body by supplying air from the channel 7 at the same time relatively strong, with slider 8 and form 10 on the one hand and housing 4 and Valve plunger 5 on the other hand are relatively slowly removed from each other.

For some cases, especially if you are spherical or ellipsoidal Want to produce flattened hollow body, it has proven advantageous to use the Manufacturing process as shown on the right half of Fig. 7 in the manner to lead that first without significant supply of blown air through the channel 7 plastic 3 pressed out of the housing 4 and housing 4 and valve stem 5 on the one hand as well as slider 8 and mold 10 on the other hand only very slowly apart so that there is a lump-shaped plastic preform II in Fig. 7 on the right forms, which is not or only very weakly inflated. After getting a sufficient has formed large lump-shaped preform 11, this is at the same time in the Drawn length and inflated, being only and to a small extent more Plastic 3 is fed from the housing 4.

The wall thickness of the resulting hollow bodies can be influenced, firstly, by inserting the housing 4 and valve stem 5 in Figs. 4 to 7 resp. Housing 14 and valve plunger 5 changed in the cross-section formed in Figs. 8 and 9, secondly, by expressing the amount of that expressed in units of time from this cross-section Plastic material larger or smaller and thirdly by moving the plastic in warmer (lower toughness of the plastic = low wall thickness) or in colder Condition (high toughness of the plastic = large wall thickness) processed. The fact, that one with this procedure shape and wall thickness of the hollow body to be produced without With the help of hollow forms 2 (Fig. 1 and 8 left as well as 9 to 12), so alone through has better control of the manufacturing process than before is in a considerable advantage in many cases. This is primarily true if you the surface of the resulting hollow body, as shown below, during the Want to influence the manufacturing process, what you have access to this surface must, or if you want to save the mold 2. But even if you are using hollow molds 2 works, has the better control of the process through the procedure described Advantages.

In fact, most of the time, value will be placed on the ones that are to be produced Blow hollow bodies into a mold. To make this possible, the housing 4 (Fig. 3 to 7) given a special shape, as shown in Fig. 8, as slim tube 14 can be formed because only then is the technical feasibility is to use a hollow form 2 TO. The housing 14 extends in the longitudinal direction through the entire hollow mold 2. The slider 8 (Fig. 8) is useful here designed so that there is part of the cylindrical wall of the plastic to be filled Forms cavity.

If a tubular housing 14 is used, the plastic 3, as shown in Fig. 8, by a piston 16 or 16 running in this housing 14 by means of a commercially available spray or spray nozzle attached to the free lower end of the housing 14 Pressing device are pressed out.

If, as shown in Fig. 8, a piston 16 is used, this will be Housing 14 with the piston 16 expediently as an independent one from the actual Bladder device, that is to say, for example, a machine part that is independent of the valve stem 5 in the form of, for example, a replaceable cartridge. This achieves that at the same time as the emptying of each located in the bladder Cartridge other cartridges 14 filled with plastic 3 outside the bladder device and can be heated, so that the bladder device as a whole is better utilized will.

The cartridges 14 (Fig. 8) can be outside of the blowing device both with the help of an injection molding machine with an already heated, in a plastic state located plastic, as with the help of a press with cold, in commercially available State of the present plastic are filled, in this latter case the cartridge 14 together with the piston 16 for so long before blowing the plastic hollow body is heated until the plastic 3, which it contains, has become plastic.

When using a slim, tubular housing 14 during the first phase of the manufacturing process (as described earlier) of the from the shape 2 (Fig. 8 left) and from the track piece 8 formed hollow space with plastic 3 filled. This must be done so that no plastic can escape in the wrong direction, seal the housing 14 against the mold 2 as shown in FIG.

During the second phase of the manufacturing process, as in Figs. 8 and 9 shown the mold 2 with the sliding piece 8 on the one hand opposite the Housing 14 and the valve stem 5 on the other hand moved while at the same time Plastic 3 pressed out through the annular slot between housing 14 and valve stem 5 and through either, as shown in Figs. 4 to 7, in the valve stem 5 drilled hole 7 or, as shown in Figs. 8 to 11, through the one in the slide 8 attached hole 15 air is blown.

Earlier it was shown how without the aid of various types Hollow forms 2 (Fig. 1 and 8 to 12), hollow bodies of very different shapes only can be achieved in that the influencing the manufacturing process of the hollow body Factors a) to d) are coordinated appropriately. In the same In a wise way, these factors influencing the manufacturing process will then also be superimposed on one another vote if you have different types of hollow bodies with the help of different types Hollow forms 2 (Fig. 1 and 8 to 12) want to produce. For example, in the Case of a very slim, tubular bottle neck shape (wine bottle) during of the manufacturing process the various factors influencing the manufacturing process a) to d) change and coordinate with one another as if one were without a hollow form Make slim, tubular, hollow bodies as shown under 11 in Fig. 7 on the left wanted to. if you have a spherical bottle hollow shape (bulbous bottles), this is how one becomes the factors influencing the manufacturing process during the manufacturing process Change and coordinate in such a way as if you were to get a spherical one without a hollow shape Hollow body II, as shown in Fig. 7 on the right, wanted to manufacture '. In this way can be used in the manufacture of hollow plastic bodies with hollow molds due to of the present process either plastic hollow bodies with more uniform wall thicknesses achieve or with greater certainty larger and, above all, slimmer hollow bodies than was previously possible with other methods.

A hitherto unknown, in many cases particularly favorable Possibility of making hollow bodies made of plastic, in particular slim hollow bodies, Fig. 9. In this way, we have already discussed several times Housing 14 and punch 5 on the one hand and form 2 and guide piece 8 on the other moved against each other while at the same time plastic 3 is pressed out of the housing 14 and blown air is supplied through the duct 15. Thereby the manufacturing process in this case by the choice of the speed with which the named parts 2, 5, 14 and 15 are moved against each other, as well as by the choice of speed, with which the plastic 3 emerges from the housing 14, as well as through the choice of the amount or the pressure of the blown air, which is supplied through the channel 15, is directed so that the plastic 3 is as immediately as possible after exiting the housing 14 on -the wall of the hollow mold 2, so this so to speak continuously with plastic 17 is laid out or lined.

This type of control of the manufacturing process, which, by the way, is a represents a particularly happy possibility, hollow bodies of the most varied Form, such as barrels, canisters, baskets, etc. to be lined with plastic film-like, is available in clear contrast to a procedure such as that shown in Figs. I, 6 and 7 and how it was described above.

The plastic is namely after the process shown in Fig. 9 Left to a lesser extent during the manufacturing process than with the procedure shown in Figs. 6 and 7 and of course incomparable to a lesser extent than with a procedure according to the method as shown schematically in Fig. 1 made clear. In other words, in a procedure according to Fig. G is a much smaller plastic surface that is not held in place by a fixed boundary available. This means that the plastic 17 is his during the blowing process It is less easy to accidentally change shape or even tear it apart can be different than with the aforementioned procedure.

This makes it possible to process plastics in a state in which they have the tendency to "flow away" because they only have a relative have very low internal strength, as is the case, for example, if thermoplastic plastics are heated to a relatively high temperature.

The processing of the plastics in a relatively highly heated, highly plastic, In a very soft state, however, it is useful, for example, if you have hollow bodies wants to blow with very thin, foil-like walls. The procedure shown in Fig. 9, explains -the possibilities for the production of seamless blown hollow bodies made of plastic with foil-like thin walls.

In order to use the device described, thin the hollow body with a thin film Produce walls, it is in some cases, among other things, expediently, the ring-shaped Exit cross-section formed by the valve stem 5 (Fig. 7) and the housing 4 is to set very tight and to a certain extent the plastic by blowing and longitudinal stretching "To pull out" of this ring cross-section, as shown schematically in Fig. 7 on the left is indicated.

In many cases it is useful to use the various previously indicated Possibilities to unite three steering of the manufacturing process and for example In the first phase of the manufacturing process, the upper part (bottle neck) of the hollow body by making a thin-walled, almost cylindrical hollow body 11 (Fig. 7 left) and then against the wall of the upper (neck) part of a Hollow form 2 (Fig. 9) blows, but in the second phase of the production process the Make the lower part (bottle belly) of the hollow body, as shown in Fig. 9.

With this approach, for example, hollow bodies can be very advantageous produce; which have a thick-walled, stable "bottle belly" with a winch for stoppers), a "bottle belly" with a film-like thin, elastic wall and one not closed have heavy "bottle bottoms". Such hollow bodies are gan for many purposes especially valuable because they are capable of being glued in some cases from plastic Bags or pouches, in other abier bottles, canisters or cans made of sheet metal or Replace glass.

One uses the process of processing plastics that are not in a highly plastic, very soft, but in a tough, solid state, so does the process for the same reasons that it does the processing of Softer plastics than other processes allowed the far safer manufacture much larger hollow bodies are possible than those previously known Process could be produced.

In some cases, especially for mass production purposes it is desirable to add the above-mentioned lump-shaped plastic preform 11 (Fig. 7 right) to give a precisely defined shape. This is done using a preform 18 (Fig. 10) is used. The slider 8 (Fig. 10) extends over a larger part or the entire length of the preform I8. The housing 14 closes in a sealing manner with the preform I8 ah. From the housing 14 so long plastic is pressed until the pre-form I8 is filled and thus a precisely defined lump of plastic in the form a preform 19 has arisen. After the preform is removed and a hollow shape 2 has been closed around the preform 19, as already described, through Inflate and stretch the front body 19 first an intermediate body 11 (Fig. 11) and finally the final hollow plastic body 20 lining the hollow mold develop.

For the purposes of mass production, one is expediently in a machine several of each one sliding body 8 (Fig. 12) and one Horizontal stamp 5 existing units and a turret-like arrangement of the corresponding machine parts ensure that, for example, to the first Unit closes a preform 18 and a preform 19 is injected while at the same time a hollow mold 2 closes around the second unit and the preform 19 is inflated and stretched while simultaneously by the third unit of the finished Holtilkörper 20 (Fig. 11) is removed.

If you want a large and complicated maso you can have an economic one Avoid exploiting the parts that move against each other, so you can get a economic utilization of the machine equipment also dadlu-rch achieve that one sliding body 8 (Fig. 12) and stretching punch 5 outside of the actual blowing device encapsulated in a suitable mold 18 with a plastic pre-body 19 and that from sliding body 8, horizontal punch 5 and pre-body 19 existing unit cartridge-like in the Blaseeinrichtun with the Holhllfofm 2 uses. The pre-body 19 is also in this case during the entire production process by means of the slide 8 and the horizontal ram (Valve temple) 5 guided or held. So it will be during the manufacturing process less easily inadvertently deform than a preform I (Fig. I). This means that one also ate with the present method when using this Last described variant plastic with greater security or in softer State can process than with the method according to Abib. I or 2, being the fact the possibility that is not available to the same extent with the method according to Fig. I or 2 the longitudinal stretching of the plastic is a very special advantage of this Procedure.

It should be noted that the previously discussed and illustrated by Fig. 9 schematically illustrated variant of the present method, of course, the Processing of plastics in an even softer state is permitted than the method shown in Figs. 10, II, 12.

Also to be mentioned is the fact that the preform 19 (Fig. 10) of course must have a different shape than a preform I (A, bb. I), The former is not only inflated but also lengthways should be stretched.

The found in connection with the present proceedings and described in-the-lengthening of the pre-body 19 (Fig. 10), in particular the Fig. II illustrated on the left, can of course also be carried out when the preform 19 is outside of the process by a method other than that described here the blower is made and nor used for the purpose of inflation in this will. So you can, for example, a preform 19 (Fig. 10) in a known manner Manufacture in an injection molding machine and then use the valve stamp (the can be referred to here as a horizontal punch 5) and slide over the slider 8. Preform I9, stretching ram 5 and slider 8 are then heated together. After this Heating up, the hollow mold 2 is closed around the preform 19, and the preform is, as already described, inflated and at the same time stretched, as illustrated in Fig. 11 on the left.

Here too, the stretching punch 5 with the slider is expedient for this purpose 8 as a separate from the blowing apparatus and in this or in a hollow form 2 unit that can be used like a cartridge. In this case several for the same blower device or the same hollow shape 2 specific preforms 19 each with a slider 8 and a stretching punch 5 simultaneously outside the blower are heated so that the actual blower with the hollow form 2 is better utilized.

The choice of all the dimensions of the manufacturing facility, for example the diameter of the outlet opening for the plastic in the housing 14 or the Valve stem 5 etc., as well as the coordination of all during the manufacturing process variable sizes on each other (for example exit speed of the plastic out of the housing 14 in relation to the speed at which the housing 14 and valve plunger 5 on the one hand and slider 8 and shape 2 on the other hand from one another remove), briefly the whole management and design of the manufacturing process of the Hollow bodies, as already indicated, one will in many cases make the the resulting plastic body 11 (Fig. 11, left) inflated as much as possible at the same time and is drawn out. The resulting stretching of the processed Plastic in two directions brings an improvement in properties some plastics with it, which is of the utmost importance. For example the originally brittle plastic polystyrene is known by stretching in two directions Beyond a certain amount it is so elastic that it can be used to produce a film. It is one of the main advantages of the method described that it is the resulting stretching of the processed plastic during the manufacturing process in the production of plastic hollow bodies allowed to go much further than allowed other processes and that this makes it possible, for example from polystyrene to produce blown hollow bodies with film-like thin and elastic walls. it is a matter of course in plastics technology that all parts of the manufacturing facility, As in the present case, for example, forms 2 in Figs. 1 and 8 to I2, or the slider 8 in Figs. 4 to I2, the one with the plastic to be processed come into contact, as well as the processed plastic itself, which is responsible for the processing must have the most appropriate temperature in each case. In the present case it has now been found that there are hollow bodies that are symmetrical on all sides for blowing, especially when these without hollow forms 2 2 (according to Figs. I and 8 to I2, i.e. roughly corresponding to Fig. 4 to 7) are to be produced is of particular importance, that the temperature differences within the for processing in the blowing device plastic that is coming should be eliminated as completely as possible.

The housing 14 to be inserted into the blowing apparatus like a cartridge is therefore useful after filling with plastic 3 so long in a boiler room Leave with the same and constant temperature everywhere until all temperature differences disappear have balanced inside.

The same applies analogously to the case that a preform Pre-body 19 brought into a defined shape is used. Also in this case it is it is important to take care that when inflating begins within the fore body there are no temperature differences.

It has also been found that for slides to manufacture hollow plastic bodies Changes in the temperature of individual layers or points dbs processed Plastic are of particular importance. For example, if you cool the valve stem 5 (Fig. 9) during the manufacturing process, vigorously, it becomes a thin layer of the plastic 17, which when flowing out of the housing 14 with .dem valve stem 5 has come into direct contact, cool and solidify.

Since this layer is only very thin, it will become in the further stretching of the plastic 17, which the blowing process has as a result, torn apart, and On the inner skin surface of the finished hollow body, a scar-like appearance arises Drawing that is desirable in some cases.

Conversely, if the valve stem 5 is heated higher than the other Corresponds to the temperature of the plastic to be processed 3 (Fig. 9), then mian a particularly smooth and shiny inner surface of the skin surface of the hollow body achieve.

If you cool the upper ring edge of the housing 14 while escaping of the plastic 3 from the housing 14 (Fig. g), so you can have a marben-like patterned Achieve outer skin of the wall of the hollow plastic body. If you heat it up, you get the outer wall of the hollow body a greater smoothness than usual. Both effects are in many cases desirable and there is a particular advantage in having them the method described can be achieved more easily than with other methods.

The same effect can be achieved if you take the place of the above Ring edge of the housing 14 the plastic 17 itself immediately after leaving the housing 14 heats or cools by blowing or spraying.

In the case of using a preform 19 can also be a Achieve pitted patterned outer surface of the wall of the finished hollow body, if a thin outer skin layer of the fore body is sharply cooled without, however to cool the entire mass of the preform. This happens, for example, in both cases you can put the hot plastic very quickly into a relatively cool preform 18 (Fig. 10) injection and the preform also opens very quickly. The outer layer of skin is then frozen due to the cooling and tears when the front body is inflated, so that a pitted pattern is achieved.

Conversely, if you want to make a preform 19 (Fig. 10) without using it a mold to produce a hollow body with a smooth outer skin surface, so used one expediently as hot a preform 18 as possible and also heats the preform 19 before inflating and stretching again. This is most conveniently done by blowing hot air or by radiant heating.

By locally cooling the skin surface of the resulting Plastic hollow body 11, which can be made, for example, by spraying or spraying with drops of coolant or by touching the plastic with heat sinks can accomplish, it is possible to create wart, lens or line-like markings to achieve in the skin of the hollow body, which is also a desirable in some cases Show effect. Such an effect is particularly evident with hollow bodies, which are blown according to the present process without a mold. But also with hollow bodies, which are blown in a mold, this effect is effective if the one used Plastic is clear or translucent. One can see this effect in the rest can also be achieved by using the processed plastic grains of another Plastic or a variety of the plastic in question with a different melting point admixed, for example in the case of polystyrene, another commercial grade.

To the caking of the finished plastic hollow body 20 and To complicate the manufacturing facility, is in the final phase of the manufacturing process expediently the valve piston or

Stretching ram 5 and the upper part of the housing 14 with the piston 16 chilled. For this purpose, cooling air can be blown into the interior of the housing 14, for example or a cooling liquid can be injected while inside the valve stem 5 appropriate cooling or heating lines are provided.

The caking of the finished plastic hollow body 20 (Ab, b. II) the valve stem 5 can also be avoided by going through the interior of the valve stem 5 supplies pressurized lubricating fluid and this through a hole provided in the middle of the front surface of the valve punch 5 between Valve plunger 5 and plastic or plastic hollow body 20 is pressed out.

To ensure precisely coordinated movements of the individual parts of the Apparatus such as the piston I6 (Fig. 8) and the valve stem 5 and the housing 14 on the one hand and the Hohlkform 2 and the slide 8 on the other hand to achieve, these parts can be machnaisch in a known manner by cam drums or pushing. But since it is very important (for example in the case of changes in the properties of the processed plastic) the course of the Manufacturing process at any time and without inconvenience. lich and time-consuming mechanical processing of machine parts such as cams etc. vary too can, it is two-way, through the movements of the individual parts of the apparatus to control light-electric cells in a known manner on paper or a scan curves that have been recorded on another surface and can be easily redrawn, whereby the electrical impulses via amplifier tubes (valve tubes) to the control valves of hydraulic drive cylinders or to the direction of rotation and number of revolutions of Electric motors act via gear pumps and hydraulic pistons or via mechanical links move the individual parts of the apparatus. The Dept. and control device is two-way in one known in control technology Giving away ways with »repatriation«.

For this purpose, for example, the piston with the photoelectric scanning device mechanically connected. The piston follows a given by the scanning device Impulse, its movement leads the scanning device back to the zero position. This The process is usually as a control with feedback or as a feedback control known.

Claims (12)

PATENT CLAIMS: 1. Device for producing seamless hollow bodies made of plastics, in which the plastic consists of one of a housing and one opposite this housing movable valve piston formed annular opening asugepreetzt and is inflated to form a hollow body, characterized in that housing (4, 14) and valve stem (5) extend in opposite directions. 2. Apparatus according to claim I, characterized in that on the Valve piston (5) a slider (8) is movable and that valve piston (5) and Rail piece (8) are sealed against each other, either in the valve stem (5) or bores (15) for the supply of blown air are provided in the track piece (8). 3. Device according to Anlsplruch I and 2, characterized in that the slider (8) is connected to a split hollow mold (2, 10). 4. Process for producing seamless hollow bodies from plastic with devices according to claim 1 to 3, characterized in that in the ratio to the amount (or speed) of this as the housing (4, I4) leaking plastic as well as in relation to the amount (or the pressure) of the blown air slider (8) and Form (2, 10) so quickly and so far along the valve stem (5) from the housing (4, I4) are moved away that the plastic other than that caused by the inflation Stretching an additional stretching in the axial direction of the resulting hollow body learns. 5. Apparatus according to claim 1, characterized in that the housing (14)) has a tubular shape, is exchangeable, and that inside the housing (4, 14) a piston (16) runs which presses the plastic (3) out of the housing (4, 14). 6. Apparatus according to claim 1 and 5, characterized in that the plastic (3) from the housing (14) through one at the free end of the housing (14) attached screw shape is pressed out in a piston press. 7. A method for producing hollow bodies according to claim 1 to 6, characterized in that the speed of the emerging from the housing (14) Plastic, the speed with the slide (8) and shape (2, 10) lengthways of the valve stem (5) are moved away from the housing (4, 14) and the amount (or the pressure) of the blown air is selected so that the aos exiting the housing (14) Plastic directly applies to the wall of a hollow mold (2) by the shortest route. 8. Apparatus according to claim 1 to 3 and 5 and 6, characterized in that that an auxiliary form (18) is provided with which the plastic becomes a compact Body (19) is preformed. 9. A method for producing hollow bodies made of plastic according to Claims 1 to 4 and 8, characterized in that a sliding piece (8) and valve stem (5) encasing preform (19) made outside the blowing apparatus and with this is inserted into the blowing apparatus like a cartridge. 10. A method for producing hollow bodies according to claim 1 to 9, characterized in that the plastic-filled housing (4, 14) and / or the preform (19) prior to insertion into the blowing apparatus for the purpose of temperature equalization be reheated in a room with a constant temperature. II. A method for producing hollow bodies according to claims 1 to 6 and 8, characterized in that a cold preform (18) is used in the plastic is pressed in at high speed that the preform (18) after opened immediately after filling and immediately after opening the preform the blowing is started, so that a thin layer of skin of the preform (19) solidifies and is torn when inflated. 12. Method for producing hollow plastic bodies according to Claims I to II, characterized in that the plastic used is grains of a different or a variety of the same plastic with a different melting point be mixed in. Referenced publications: German patent specification No. 529 469.