DE2400951A1 - METHOD AND DEVICE FOR THE MANUFACTURING OF PLASTIC BOTTLES - Google Patents

Description

PA Γ EN 'ΓΑ N WA LT E

DR. ING. A. VAN DERWERTH - DR. FRAN Z LE DE RE R

21 HAMBURG 90 β MÖNCHEN 80

WITSTORFERSTR 32 TEL. (O40J 770861 LUCILE-CRAHN-STR. 22 · TEL. (08 111 * 7 29 - »7

Munich, January 9th 19.74

M / ta

IBS X

Applicant: 4 P Verpackungen GmbH,

896o Kempten, Allgäu, Ulmer Str. 18

Method and device for the production of plastic bottles.

The invention relates to a method for producing plastic bottles, in which first a plastic body (Preform), in particular by injection molding, is made of plastic, the plastic body on a Temperature of the thermoelastic area of the plastic is tempered, an inflation of the entire plastic body tempered in this way, with the exception of the edge of the bottle opening forming part with the associated molecular orientation of the plastic to the finished bottle shape and then the bottle is cooled while maintaining the molecular orientation of the art Substance is carried out.

The invention also relates to a device for performing the method, namely a device with a first workstation for the production of a plastic

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DEUTSCHE BANK AO .. HARBURC 93 / 208IS POSTSCHECK! HAMBURG 1173 20-206 TELEGRAMS! LEATHER PATENT MÖNCHEN

body (preform), in particular by injection molding of the plastic, around a mandrel located within a correspondingly designed mold, with another work station for tempering the plastic body to a temperature of the thermoelas fish Area of the plastic and with a last work station for inflating the entire, so tempered and the plastic body still on the mandrel with the exception of its forming the edge of the bottle opening Partly within a blow mold with the associated molecular orientation of the plastic to the finished bottle shape and to cool the bottle while maintaining the molecular orientation of the plastic and to Ejection of the bottle from the device.

The method of the type described above is generally under the. also the abbreviation used in the following IBS procedure (injecting-blowing-stretching). Procedure known. In this method, in a repeated description, in other words, preforms are first used made of amorphous plastics such as PVC, for example injected, these preforms to temperatures of thermoelastic state of the plastic and then with simultaneous stretching, i.e. molecular orientation of the plastic, inflated into bottles. This process is particularly important with regard to the improvements in properties that can be achieved thereby the finished bottle is particularly advantageous in terms of strength and gas tightness. One downside to this However, the method consists in that starting from a certain size of the, for example, injected preform only bottles of certain maximum sizes can be produced, since care is taken when inflating must that a certain yield point of the plastic

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is not exceeded, since above this limit there will be signs of tearing in the plastic. Under this and also other aspects are for a proper production of plastic bottles according to the IBS process the following statements are of particular importance.

The elongation at break of amorphous plastics is strongly temperature-dependent in the temperature range of the thermoelastic state of these plastics and reaches, for example, for PVC, K value 57, a maximum value of approx. 500% or a degree of stretching of approx. 6: 1 at a temperature of approx . 92 ° to 94 ^Oi C. Since the one hand, to achieve an optimum bottle wall thickness and an optimum Re.ckgradverteilung preforms must be used with the bottom towards increasing wall thickness and since consequently the other hand, to achieve an optimum Blasverhaltens the preforms in depending on their wall thickness profile of a respectively optimum and must be assigned a temperature profile characterized by increasing temperatures in the direction towards the bottom, it follows from this that not all parts of the preform with regard to their temperature can be in the range of the maximum elongation at break; this applies in particular to the lower areas of the preform, from which the lower area of the bottle body and the bottle base are to be formed by the aforementioned inflation. In the above-mentioned areas of the preform, as a result of the higher temperatures in these areas, the elongation at break limit is already reached at values of elongation or degree of stretching lower than those specified above The degree of stretching of only 4.5: 1 must be expected. This in turn means that when the total stretching is divided up, for which the maximum value of the stretching degree of 4.5: 1 is to be set, on the one hand stretching in the circumferential direction and on the other hand stretching in the longitudinal direction, taking into account a more pressure-resistant for the production Bottles with a favorable distribution ratio of 2: 1

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this results in a value of 1.5: 1 for the degree of stretching in the longitudinal direction and a value of 3: 1 in the uro-tangential direction. This value of 3: 1 for the maximum possible degree of circumferential stretching also represents the ratio from bottle diameter to given mouth diameter. This in turn means that depending on the the bottle diameter to be executed is the mouth or cap diameter must have certain minimum values.

If bottles with a capacity of 0.5 liters or more are to be produced, the above-mentioned relationship between the bottle diameter on the one hand and the mouth or mouth diameter on the other hand results in the production of bottles. Closure diameter various _f very serious disadvantages. A first disadvantage is that correspondingly large closures are neither available on the market nor even exist as standard closures and are therefore, on the one hand, to be newly developed and, on the other hand, are expensive due to the increased material requirements and / or the small number of pieces. Another disadvantage is that in order to achieve a good seal tightness under the requirement of causing certain surface pressures in the seals with increasing closure diameter and in comparison to the neck wall thickness which decreases as a result of the stronger inflation, increasing closing forces have to be applied to the bottle neck, from which the There is a risk of compression or this risk increases. Furthermore, when plastic closures are used, the gas permeation increases with increasing closure diameter. Furthermore, to ensure the necessary sealing tightness in particular in stress on internal pressure and in particular in metal closures higher material _s tärken required. Another disadvantage is that, assuming a constant bottle weight, the flow

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resistance in the injection mold with increasing mouth diameter and decreasing wall thickness of the preform increases exponentially, so that increased demands on the tool design and precision are to be asked in order to avoid wall thickness errors and the resulting poorer controllability of the manufacturing process to avoid. Another disadvantage is that when using closures each of a different diameter correspondingly changed or adapted filling and closing machines are used Need to become.

Another very significant disadvantage of the IBS process is that by means of this process crystalline or partially crystalline plastics do not lead to bottles with optimal wall thickness and stretching degree distributions can be processed; and this is due to the fact that with Stretching temperature at the crystallite melting point has a very steep course of the modulus of elasticity over the temperature with a constant temperature distribution in the preform would have to be worked. Such a temperature distribution can be However, this can hardly be achieved in practice in the case of conical preforms with wall thickness increasing in the direction towards the bottom and moreover leads to an uncontrollable deformation behavior during stretching or inflation. On the other hand, the use of preforms with constant wall thickness would either result in bottles with non-uniform Wall thickness distribution with weak spots in the floor area or lead with insufficient stretching degrees in this area. The former is at compared to the bottle length short and the latter is the case with preforms of the same length,

From US Pat. No. 2,715,751, a method for producing bottles is known in which, following the production by injection molding of the preform this still continues on the

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The preform located in the mandrel is removed from the injection mold and placed in an intermediate mold. In this intermediate form, compressed air, for example, is fed into the interior of the Preforms for at least partial detachment introduced by the mandrel, after which the still on the mandrel and correspondingly slightly and at least partially expanded preform is removed from the intermediate mold and introduced into a blow mold, in which inflation of the preform to the shape of the finished bottle is carried out. The said minor and at least partial intermediate inflation of the preform serves the purpose of preventing tearing of the preform during final inflation due to the tendency of the hot plastic material for sticking to the metal surfaces of the mold. For this reason, the known intermediate inflation is only allowed one result in slight expansion of the preform, so that the preform is not destroyed can occur during intermediate inflation.

Based on the known IBS process and the The device of the generic type described at the outset is based on the object of the present invention, the stated The method and the associated device continue in this way form and improve so that the disadvantages specified above in detail and in detail can be avoided. This means that it should be possible to produce plastic bottles which, on the one hand, have a large ratio between them Have bottle body diameter and the bottle mouth diameter and / or which are made of partially crystalline or made of crystalline plastics.

This object is according to the invention from a procedural point of view solved in that in the plastic body (preform) following its manufacture in the injection molding process a desired temperature distribution within

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of the thermoplastic area of the plastic is produced so that the preform, which is tempered in this way, becomes at least one In some areas, a much larger bladder made of non-oriented plastic is inflated (intermediate inflation) that in this blasling with essentially complete maintenance of its shape and size. a desired temperature distribution is generated within the thermoelastic region of the plastic and that then the molecular-orientated inflation to the finished bottle shape is carried out.

According to the solution to the problem just given, it is an absolutely necessary one that cannot be overlooked Characteristic of the method according to the invention that in the inflation to the final bottle shape by no means like this is the case with the IBS procedure, from a plastic body in the size and shape of the preform is assumed, but rather from that already by intermediate inflation of the Preform formed bladder, which at least in partial areas the same has a much larger shape than the preform. Furthermore, this is by no means negligible Way to note that the intermediate inflation of the parison to form the parison occurs with a temperature distribution is to be carried out within the thermoplastic temperature range of the plastic, so during this Interim inflation no molecular orientation of the plastic takes place. Otherwise it would occur during intermediate inflation any expansion of the plastic must be added to the expansion during the final inflation of the bottle, so that the maximum permissible elongation has been exceeded. Due to the temperature control of the preform according to the invention a temperature distribution within the thermoplastic area and the resulting intermediate inflation which is free of molecular orientation it is possible to fully use the maximum permissible value of the total elongation or the total degree of stretching in the final Exploit inflation to the finished bottle shape. In this way it is possible to proceed proportionally from a preform small diameter, namely a diameter that

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for the mouth diameter of the finished bottle is characteristic, a finished bottle of considerably larger bottle body diameter to produce, with between said bottle diameter and the mouth diameter there is a ratio which is significantly greater than the maximum permissible value of the degree of stretching; the said ratio can, for example, be twice or a greater multiple of the maximum value of the degree of stretching.

Furthermore, the inventive design or further development of the known IBS method created the possibility for the first time to use partially crystalline or crystalline plastics as starting products for the production of plastic bottles and to be able to process them into the plastic bottles. This further new and advantageous possibility of the method according to the invention is due to the fact that the intermediate inflation of the preform provided according to the invention forms a bladder whose wall thickness or wall thickness distribution, which is reduced compared to the preform, is responsible for the generation of the final inflation finished bottle allows the necessary temperature distribution. While the final inflation has so far been carried out in the preform, i.e. with a plastic body with a relatively thick wall thickness, as a result of which the necessary temperature distribution for preforms made of partially crystalline or crystalline plastics could not be generated in the usable manner and correctness, is now from the Assumed a bladder with a thinner wall thickness, which allows the above-mentioned generation of the temperature distribution. The method according to the invention is therefore far superior to the known IBS method in terms of its applicability.

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In an advantageous development of the method according to the invention it can be provided that the thermoplastic Intermediate inflation of the preform on the entire preform with the exception of the edge of the bottle opening forming edge is carried out. Another further training measure of the method according to the invention can consist in that the thermoplastic intermediate inflation at different circumferential and / or height areas of the preform is carried out. In the case of the first training measure, it is possible, for example, bottles or to produce equivalent hollow bodies, the cross section of which, for example, provided in the bottom area, extends over the whole Bottle height extends. On the other hand, on the basis of the second training measure, it is possible to use bottles as well to produce other hollow bodies with more or less uniformly distributed localized widenings, in particular For example, elliptical cross-sections of different shapes in different height areas of the Bottles come into question. Such bottles are for example due to their special display effect in preferred in certain market areas.

In terms of device technology, the specified object is achieved in that the first workstation has a further work station for tempering the preform to a temperature of the thermoplastic area of the Plastic is downstream that this downstream

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Work station another work station for the intermediate inflation of the preform thus tempered to one at least partially significantly enlarged plastic body (bladder) within a correspondingly designed Intermediate blow mold is connected downstream and that this intermediate blow station at the same time that station for the Tempering the plastic body to a temperature of the thermoelastic area of the plastic.

Advantageous further training measures for the device according to the invention can consist in the fact that the entire Intermediate blow mold with the exception of the area to be assigned to the edge forming the edge of the bottle opening opposite the Injection mold is enlarged or that the intermediate blow mold at different circumferential and / or Height areas compared to the injection mold is designed to be differently enlarged.

With regard to the advantages achieved by the device according to the invention, reference is made to the relevant statements to the method according to the invention and also to the more detailed description of the content of the Drawings referenced.

In the following, the entire invention, i.e. that of the invention, will be described Method and the associated device, going further in detail with reference to the drawings described; in this shows:

FIG. 1 shows a schematic representation of what is essential for carrying out the method according to the invention Part of the associated device, which at the same time in terms of device technology is affected by the invention,

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FIG. 2a longitudinal section / through a preform, 2b a bladder produced from this by intermediate inflation 2c and one from the latter bottle made by final inflation,

FIG. 3a again shows longitudinal sections through a preform 3b, a blister and a finished one 3c bottle, with blasling and bottle each

two provided at different heights and extending over the entire circumference Have bulges, and

FIG. 4a shows a plan view of a further bottle 4b and two longitudinal sections through the same ge-4c measured line IVb-IVb or IVc-IVc of Figure 4a.

In Figure 1 is a rotatably arranged on a boom of a machine, not shown, mandrel carrier 1 four thorns 2 shown. This mandrel carrier 1 can be advanced step by step in the direction of arrow A in such a way that that all mandrels located in a particular work station each around a work station to be advanced. Overall, in the mandrel carrier 1 shown in Figure 1, four work stations I, II, III and IV provided.

As shown in Figure 1, the mandrel 2 located in the work station I is surrounded by an injection mold 3 which is made in one piece and between the inner wall and the outer surface of the mandrel 2, an annular cavity consists in which the plastic from which the bottles are to be made, for example by injection molding is to be brought in. In addition to the annular shape of the cavity, it is located in the area of the free end of the mandrel nor via a connection cavity which is used to produce a bottom part of the preform. To remove the two

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for example by injection molding on the mandrel 2 The preform produced in the work station I from the injection mold 3 is well known Way in the direction of the arrow B by means of mechanical, hydraulic or pneumatic sliding devices directions from the mandrel carrier 1 moved away. As a rule, this movement away of the injection mold 3 takes place at the same time with the injection unit downstream of the injection mold 3, from the one in FIG. 1 only to indicate it the plasticizing screw 5 is still partially shown.

The mandrel 2 located in the work station II is surrounded by a two-part tempering mold 6, by means of which the preform located on the mandrel 2 to a temperature the thermoplastic area of the plastic used in each case can be brought. For this purpose are on the tempering mold 6 only schematically shown heating means 7 is provided. These heating means 7 can be in any Be designed, for example, as induction heating means, as continuous heating means for hot water, steam, air or similar. Furthermore, on the tempering mold 6 again only schematically indicated coolant 8 is provided, which is basically designed in the same way in terms of its structure can be like the heating means 7 according to the description given above. In principle, it should be noted that the Workstation II indicated arrangement of both the heating means 7 and the cooling means 8 in no way for the implementation of the method according to the invention is necessary. In practice, the arrangement of the heating means 7 and the To align the coolant 8 with what temperatures and in particular with what temperature profile the preform coming from workstation I is fed to workstation II and with which temperature profile it is fed from the the latter station of the intermediate inflation in the working

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station III is to be supplied. The cooling means 8 are used in particular in combinative Zusaminenwirkung * with the heating means 7 for forming an optimum temperature for the Zwischenauf blowout profile of the preform, said temperature profile has to be in the thermoplastic range of the plastic.

In the area of work station III is the preform still on the mandrel: 2 and thus also the mandrel 2 is surrounded by a two-part intermediate blow mold 9, so that when the preform is inflated by means of air supplied in a known manner through the interior of the dome 2 to form the preform Blasling is inflatable, the shape of which is that formed by the inner boundary surface of the intermediate blow mold 9 Shape corresponds. The parison formed in this way is therefore seen as a whole, namely in the longitudinal direction and / or Seen in the circumferential direction, larger than the preform. These Enlargement of the preform to form the parison by way of intermediate inflation relates to the preform in the depicted Case of Figure 1 in its entirety with the exception of that part of the preform which later forms the opening edge of the finished bottle. This from the intermediate inflation unaffected part of the preform remains unchanged in terms of its shape. Because the preform prior to its intermediate inflation to a temperature of the thermoplastic area of the plastic has been tempered, the plastic remains molecularly misaligned during the intermediate inflation to the bladder, i.e. there is no stretching of the same to improve the properties of the plastic.

In addition to the intermediate inflation described, the temperature of the bladder is controlled to a temperature in work station III

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Temperature of the thermoelastic area of the plastic. For this purpose, there are 9 heating means on the intermediate blow mold Io and coolant 11 provided for their formation and arrangement the above remarks on the Heating means 7 and the cooling means 8 of the tempering mold 6 apply unchanged.

In the next workstation, workstation IV, is the bladder still on a mandrel 2 surrounded by a blow mold, again made in two parts. The interior of this blow mold 12 corresponds to Shape of the bottle to be produced, onto which the bladder in turn passes through the bottle to be passed through the interior of the dome 2 Blown air is inflatable. During this inflation of the bladder to form the finished bottle, the in the workstation III provided temperature control of the Molecular-orientated stretching to a temperature of the thermoelastic area of the plastic of the plastic, so that the finished bottle has special and targeted strength properties after it has cooled down and has other properties. To carry out the cooling mentioned, there are 12 coolants on the blow mold intended. During this cooling by means of the coolant 13, the blown bladder, which has been blown into the finished bottle, stands under an internal pressure, so that the solidification of the plastic by cooling while maintaining the Molecular orientation is carried out.

The mold halves of the tempering mold 6 or the intermediate blow mold 9 and the blow mold 12 are perpendicular to the plane of the paper in FIG Workstation II or III and IV process steps to be carried out moved apart in order for the purpose of

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Forwarding of the mandrel carrier 1, the mandrels 2 together with the plastic bodies located on them with the To bring forms 6,9 and 12 out of engagement. The finished blown bottle is stripped off in the station IV by actuating the axially displaceable on the mandrel Stripper 19, this axial displacement with the help suitable means contained in the mandrel carrier 1, but not shown in Fig.l, made in a known manner will.

In the example shown in FIG. 1, according to the description already given, the tempering mold 6 is in two parts and its halves can be moved apart perpendicular to the plane of the paper in FIG. 1 to release the dome 2; However, such a design of the tempering mold 6 is by no means absolutely necessary; Tempering mold 6 can also be made in one piece and by a radial movement away from the mandrel carrier 1 out of the area of the mandrel 2 can be moved away. The blow mold 12 can also be moved away from the mandrel carrier 1 in the radial direction, at the same time the stripping of the bottle not as described above with the aid of the stripper 19, but with the aid of in this case, the blow mold 12, which acts as a stripper and is pulled off in the closed state, takes place. The removal the bottle from the blow mold 12 by opening both of them

Halves found after partial or complete radial The blow mold is moved away from the area of the mandrels 2.

The parts of the device not touched by the invention, for example the entire injection unit, the device frame, the drive means for the mandrel carrier1, electrical, mechanical, hydraulic or pneumatic Supply units and facilities are not shown in the drawings in order to convey the essence of the To better express the invention.

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Figures 2a, 2b and 2c illustrate the invention Method based on a comparison of a preform 14, one from the preform 14 by intermediate opening Blasling produced Blaslings 15 and one from the Blasling 15 produced by final inflation of the Sov7ohl bottle for the bladder 15 as well as for the finished bottle it is a hollow body of substantially cylindrical shape. Figures 2a, 2b and 2c are not necessarily to be understood to scale, but can certainly be understood to scale, so that from Such a consideration of the representations of these cited figures shows that from the preform 14 a bottle 16 can be produced which is considerably larger than the preform, both in the circumferential direction as well as in the longitudinal direction, the opening edge 17 of the bottle 16 having the same diameter as the corresponding one Area of the preform 14; Incidentally, this also applies to the opening wheel of the blown blow 15.

In FIGS. 3a, 3b and 3c there is again a preform 14, a bladder 15a and a finished bottle 16a are shown. Blasling 15a and finished bottle 16a differ in In this case, however, from the bladder 15 or the bottle in that two arranged at different heights and there circumferential bulges 18 are provided, the preform having a wall thickness profile in its longitudinal direction can have, due to which a uniform wall thickness distribution can be achieved in the bottle.

In FIGS. 4a, 4b and 4c, a further one is in the way of the invention Method and bottle 16b that can be produced by means of the device according to the invention are shown. With this bottle Elliptical bulges 18a and 18b are provided in two different height areas, which are at 90 ° to each other are offset.

Finally, for the sake of completeness, it should be stated that the procedures provided with regard to the method according to the invention Temperature control of the preform or the blow molding based on temperature distributions within the thermoplastic or

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thermal load area of the plastic not necessarily are to be carried out in a single workstation of the associated device, but quite in several successive workstations can be brought about. It is only essential for the temperature control mentioned, that said temperature control of the preform must be completed before the beginning of the intermediate inflation of the preform to form the parison.

Finally, it is finally stated that it is in the device according to the invention for implementation of the method according to the invention in no way involves a device with a mandrel carrier according to FIG. 1 must act, but that the mandrel-bearer can also be designed differently; The only important thing here is that the mandrels of the mandrel carrier also otherwise aesthetic are consecutively different work stations in the According to the description according to the invention of the device can be supplied.

With regard to the terms "crystalline or partially crystalline plastics" used repeatedly above is explained on "VDI guidelines 2008" sheet 1 (May 1967 edition) and sheet 2 (July 1967 edition) and on "Kunststofftaschenbuch" 1971, pages 10-13 and 155-157 referenced. In some cases, the very narrow width of the temperature range for such plastics is even shown in the drawing specified, in which a thermoelastic processing is possible, from which inter alia. many difficulties can be seen, which are overcome by means of the present invention.

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Claims (7)

Patent claims: 1.] Process for the production of plastic bottles, in which first a plastic body (Preform), in particular by injection molding, is made of plastic that Plastic body tempered to a temperature of the thermoelastic area of the plastic is, an inflation of the entire, so tempered plastic body with the exception of his the part forming the edge of the bottle opening with the associated molecular orientation of the Plastic to the finished bottle shape and then a cooling of the bottle below Maintaining the molecular orientation of the plastic is carried out, characterized in that that a desired temperature distribution in the plastic body (preform) following its manufacture is generated within the thermoplastic area of the plastic that the so tempered Preform to form a parison made of non-oriented material that is substantially larger, at least in some areas Plastic is inflated (intermediate inflation) that in this bubble under essentially complete Maintaining its shape and size a desired temperature distribution within the thermoelastic Area of the plastic is generated and that this is followed by the molecular-oriented inflation is carried out to the finished bottle shape. - 19 - 509029/0428 2. The method according to claim 1, characterized in that the thermoplastic intermediate inflation of the preform on the entire preform with the exception of its forming the bottle opening edge Partly is carried out. 3. The method according to claim I _1, characterized in that the thermoplastic intermediate inflation of the preform on different circumferential and / or height areas of the preform different is carried out strongly. 4. The method according to any one of claims 1 to 3, characterized in that a part or. crystalline plastic Is used. 5. Device for performing the method according to one of the preceding claims, with a first Work station for the production of a plastic body (Preform), in particular by way of injection molding of the plastic, to a corresponding within a shaped mandrel located around, with another work station for temperature control of the plastic body to a temperature of the thermoelastic area of the plastic and with a last work station for inflating the entire temperature controlled in this way and the plastic body still on the mandrel with the exception of its part forming the edge of the bottle opening within a blow mold and associated therewith Molecular orientation of the plastic to the finished bottle shape and to cool the bottle while maintaining the molecular orientation of the plastic and ejecting the bottle from the Device, characterized in that the first work station (I) is followed by a further work station (II) for tempering the preform (14) to a .Temperature of the thermoplastic area of the plastic downstream is that this downstream work 509329/0428 - 2o - station (II) another work station (III) for intermediate inflation of preforms at such a temperature (14) to an at least partially enlarged plastic body (bladder) (15) within a corresponding designed intermediate blow mold (9) is connected downstream and that this intermediate blow station (III) at the same time the workstation for tempering the plastic body to a temperature of the thermoelastic Area of the plastic is. 6 · Device according to claim 5, characterized in that the entire intermediate blow mold (9) with the exception of the part to be assigned to the bottle opening edge opposite the Production mold (3) for the preform (14) enlarged is trained. 7. Apparatus according to claim 5 ^, characterized in that the intermediate blow mold (9) at different Circumferential and / or height areas of different strengths compared to the production mold (3) for the preform (14) is formed enlarged. +) des 5O9829 / CU2Ö Blank page