DE102013102325A1 - Method and device for producing large-area hollow bodies - Google Patents

Abstract

A method is described for producing a hollow body (10, 122) made of thermoplastic material in a blow molding process with a blow mold (62, 120, 144) comprising at least two blow molded parts (58, 60). In the opened blow mold (62, 120, 144) at least two preforms (54, 56, 104, 106, 136, 138) are brought into juxtaposition. The blow mold (62, 120, 144) is then closed and the preforms (54, 56, 104, 106, 136, 138) are formed separately from one another by inflation to individual chambers (12, 14, 112, 114). The individual chambers (12, 14, 112, 114) weld together at mutually facing sections and together form a hollow body (10, 122).

Description

The invention relates to a method and an apparatus for producing a hollow body of thermoplastic material in the blow molding process.

Large-area hollow bodies are hollow bodies which have a small height in relation to their length or width. Such hollow bodies are used for example as wall or door elements for industry use, for. B. for clean room cells, cooling chambers and sanitary cells.

Such hollow bodies are produced by a blow molding by blow molding. The blowing system comprises an extrusion head which is usually circular in cross-section and whose nozzle circumference has at least twice the width of such hollow bodies for the production of large-area hollow bodies. For example, an extrusion head to produce about 2 meters wide hollow bodies requires a diameter of about 1.3 m. Such extrusion heads are extremely expensive to produce, therefore relatively expensive and have the disadvantage that due to the process, a relatively large slug is created, which adversely affects the output of the blower.

It is an object of the invention to provide a simple method and an apparatus for producing large-area hollow body.

This object is achieved for a method having the features of claim 1 and for a device having the features of claim 14. Advantageous developments are specified in the dependent claims.

According to the invention, a method for producing a hollow body made of thermoplastic material in the blow molding process is specified, in which the blow mold used in this case comprises at least two blow molded parts and can assume an open or a closed state. In the open state of the blow mold blow moldings are spaced apart so that preforms are introduced into the blow mold. When closed, the blow moldings touch in such a way that the preforms are blown to the hollow body. The blow moldings may be, for example, symmetrically flared blow mold halves. The blow moldings may also be asymmetrical, e.g. Also, a blow molding as a cavity and the other blow molding can be formed flat. The use of several blow moldings for a blow mold is possible.

In the open state of the blow mold at least two preforms are placed in juxtaposition between the blow moldings. In this context juxtaposition means that the preforms initially do not touch. When closing the blow mold and simultaneous or subsequent inflation, the preforms are deformed so that they come into contact at the facing areas, wherein for each preform a separate compressed air supply, for example in the form of a blowing needle or a mandrel is provided. During the blowing process, the preforms weld to the facing surfaces.

The invention primarily enables the production of large-area hollow bodies with a height-width ratio of, for example, 1 to 5 to 100 and with a hollow body length which is greater than the hollow body width. Flat hollow bodies of this type have, for example, an article width of 2 m, an article height of 5 cm and an article length of up to 6 m.

Characteristic of hollow bodies which are produced by this method is that they have a longitudinal web extending in the longitudinal direction of the hollow body. Hollow bodies, which consist of more than two individual chambers, correspondingly have a plurality of such longitudinal webs. So hollow bodies, which consist of three individual chambers, thus two longitudinal webs, etc. However, the method can not be limited only to the production of flat hollow bodies, but can also be applied to the production of other hollow bodies, which consist of several individual chambers.

Preferably, at least two extrusion heads are arranged at a distance from each other. In this case, the number of extrusion heads corresponds to the number of preforms required for producing the hollow body, so that at the same time all the preforms for the hollow body to be molded are extruded. The extrusion heads are arranged at such a large distance from each other that the preforms do not touch each other during extrusion. This effectively prevents welding of the preforms prior to introduction into the blow mold.

In one embodiment of the method, the extrusion heads are arranged above the blow mold such that the preforms are in the required juxtaposition after extrusion and prior to closing the blow mold.

In another embodiment, at least one of the extrusion heads may be slidably mounted so that the preforms are brought into juxtaposition by displacing the movable extrusion heads prior to closing the blow mold. Subsequently, the blow mold closed and blown the preforms to the hollow body.

In a further embodiment of the method, the extrusion heads are arranged such that the preforms are extruded outside the opened blow mold. In order to allow the transfer of the preforms into the intended position in the open blow mold, either the blow mold is moved into the appropriate position under the extrusion heads or the extrusion heads are brought into the appropriate position above the blow mold.

In a variant of the aforementioned embodiment, the transport of the preforms from the extrusion heads to the blow mold takes place by means of a gripping device. Preferably, the extrusion heads are equidistant from each other as the preforms are to be positioned in the blow mold. Thereafter, the blow mold is closed and the preforms are blown to the hollow body.

In the embodiment described above, the extrusion of the preforms can be carried out both continuously and discontinuously. Which of the two methods can be used depends on the length of the preforms, the meltability of the extrudate and the cooling time of the hollow body in the closed blow mold. In continuous extrusion, the melted material produced by the extruders is continuously extruded from the extrusion head as a preform, while in the batch process the melted material is conveyed to a melt store for later application as a preform in a relatively short period of time.

If the extrusion time of the preforms takes too long - due to an excessively long cooling time of the hollow body in the blow mold - the preform loses too much heat of fusion and, as a consequence, the blowing process can no longer be reliably controlled. Thus, with short cooling times and not too long preforms, the continuous process can be used; For long cooling times and / or long preforms, the batch process can be used advantageously. The advantage over the discontinuous embodiment is the shortening of the cycle time, because the extrusion of the preform can already take place with the blow mold closed.

In a further embodiment of the method, only one extrusion head is provided which successively extrudes the preforms, which together form the hollow body. A gripping device with at least one gripper takes the preforms individually from the extrusion head and transports them one after the other between the blow moldings of the opened blow mold and arranges them in juxtaposition. After the last preform has been arranged, the blow mold is closed and the hollow body is blown as already described above. In this embodiment of the method, only the discontinuous extrusion of the preforms can be used, because the transfer of the first, the second and optionally all other preforms into the open blow mold has to take place in a short time sequence.

In an additional embodiment, at least two extrusion heads are provided, wherein more preforms are required for forming the hollow body than extrusion heads are provided.

A gripping device with at least two grippers transports the preforms in sub-sets one after the other to the opened blow mold and arranges them there in juxtaposition. Only when all the preforms required for producing the hollow body are transported between the blow moldings of the opened blow mold, the blow mold is closed and the hollow body blown as already described above.

In a preferred embodiment, all preforms of a hollow body, each with a separate mandrel or a separate blowing needle are blown simultaneously with the same parameters. This means in particular that in each preform the same gas is injected with the same gas pressure. In this case, all preforms expand the same, so that the hollow body has a constant high-quality surface structure.

Preferably, the hollow body cools in the closed blow mold, while each preform is subjected to a uniform gas pressure. As a result, pressure differences of the gas filling of the individual preforms are avoided. This effectively prevents the preforms from expanding differently and the resulting hollow body from having irregularities.

It is advantageous that the hollow body produced in the interior has continuous longitudinal webs with a wall thickness substantially double compared to the outer wall. These longitudinal webs stabilize the hollow body particularly effectively, without the restrictions on the surface design of the front and rear walls of the hollow body. If the longitudinal webs are not sufficient for absorbing the forces on the front or rear wall, the opposing walls can additionally be supported against one another by means of taps.

According to a further aspect of the invention, a device is specified with which Hollow body made of thermoplastic material can be produced by the method according to the invention. For this purpose, the device comprises a blow mold comprising at least two blow moldings and at least one extrusion head, from which preforms are preferably extruded discontinuously. The extruded preforms are placed between the blow moldings of the opened blow mold so that they are deformed into single chambers in the closed blow mold and touch and weld on facing portions.

In one embodiment of the device, at least two extrusion heads, at least one of which is displaceable from a first position to a second position, are arranged above the blow mold and preferably extrude the preforms intermittently between the blow moldings of the opened blow mold. In this case, the movable extrusion heads are arranged in the second position, so that the preforms are spaced from each other during extrusion, so do not touch. After extrusion, the slidably disposed extrusion heads and thereby also the extrusions extruded from these extrusion heads are displaced to the first position, thereby bringing the preforms into juxtaposition. After the subsequent closing of the blow mold, the preforms are blown to the hollow body.

In another embodiment of the device, at least two extrusion heads are provided, which are arranged in a third position and extrude preforms. The apparatus further comprises a gripping device with at least two grippers, preferably as many grippers as extrusion heads, which remove the extruded preforms from the extrusion heads and transport them between the blow moldings of the opened blow mold. While the preforms are blown to the hollow body, the preforms of the next hollow body are already extrudable.

In a further embodiment variant of the device, at least one extrusion head, which is positioned outside the blow mold, is provided, which extrudes the preforms of a hollow body, preferably discontinuously one after the other. After extrusion, each preform is removed from the extrusion head by means of a gripping device and placed between the blow moldings of the opened blow mold. After the last of the respective hollow body forming preforms is arranged, the blow mold is closed and the hollow body is blown.

Embodiments of the invention will be described below with reference to the drawings. It shows:

1 a hollow body according to the invention in a partially sectioned plan view;

2 a sectional view along the sectional plane AA after 1 ;

3 a sectional view along the section plane BB after 1 ;

4 a perspective schematic representation of an apparatus for producing a hollow body of two preforms with the method referred to as discontinuous;

5 the blowing of a hollow body consisting of two preforms after the in 4 shown methods;

6 a sectional view along the cutting plane CC after 5 ;

7 a schematic representation of an apparatus for producing a hollow body with the method referred to as continuous; and

8th a schematic representation of the method according to the invention, in which the preforms are transported one after the other in the blow mold.

1 shows a hollow body 10 in a partially sectioned plan view. The hollow body 10 is made up of the individual chambers 12 and 14 together, from the preforms 54 and 56 (in 4 shown) were formed and welded together at their facing portions. They form a longitudinal ridge there 16 out, along the hollow body 10 from a first end face 18 up to a second end face 20 runs. The longitudinal bar 16 separates a first interior 26 the first single chamber 12 from a second interior 28 the second single chamber 14 and supports a front wall 22 against a back wall 24 of the hollow body 10 by pointing to the front or back wall 22 . 24 acting forces on the opposite rear or front wall 24 . 22 derives. Here is the respective front or rear wall 22 . 24 in the area of the longitudinal ridge 16 smooth.

Furthermore, the hollow body 10 by additionally shown as an example bungs 30 . 32 . 34 . 36 . 38 . 40 reinforced, as are known in the general state of the art. The naps 30 to 40 can be designed arbitrarily and serve mainly the stiffening of the hollow body 10 ,

2 shows a sectional view of the hollow body 10 along the in 1 registered section plane AA. In the cut shown Vernapfungen 34 . 38 it can be seen that wall areas of the front wall 22 and the back wall 24 welded together. In 2 is good to see that the hollow body 10 is very flat, with the distance between the front wall 22 and back wall 24 in comparison to the distance between the two end faces 18 . 20 each other is very small.

3 shows a sectional view of the hollow body 10 along the in 1 registered section plane BB. Between the first interior 26 and the second interior 28 is the longitudinal bar 16 , This longitudinal ridge 16 has one compared to the outer wall of the hollow body 10 in about double wall thickness, since both chambers 12 . 14 are welded flat. Also, it can be clearly seen in this figure that the hollow body 10 is flat, because the distance between the front wall 22 and the back wall 24 is much less than the distance between a first side surface 42 and a second side surface 44 ,

4 shows schematically a perspective and partially sectional view of elements of a device 50 for producing a hollow body 10 from two preforms 54 . 56 in the process referred to as discontinuous. The device 50 includes the extrusion heads 66 and 68 as well as a blow mold 62 made from a first blow-molded part 58 and a second blow molding 60 which, as indicated by the arrows P6 and P7, can be brought into contact with each other and the blow mold 62 form. The plane in which the blow-molded parts 58 . 60 with closed blow mold 62 touch, is called a mold parting plane 64 designated.

Above the blow mold 62 are two extrusion heads 66 . 68 arranged, which are mounted independently of each other displaceable relative to each other, as indicated by the arrows P1 and P2. The extrusion heads 66 . 68 each extrude a preform 54 . 56 in the direction of the extrusion direction indicating arrow P3 or P4 between the blow moldings 58 . 60 the open blow mold 62 , wherein the preform 54 from the extrusion head 66 and the preform 56 from the extrusion head 68 is produced. Here are the extrusion heads 66 . 68 spaced so far apart that the preforms 54 . 56 do not touch during extrusion. After complete extrusion, there is a possibility that at least one of the extrusion heads 66 . 68 can be moved until the preforms 54 . 56 in juxtaposition between the blow moldings 58 . 60 the open blow mold 62 are arranged.

Furthermore, the device comprises 50 two, each in the mold parting plane 64 arranged mandrels 70 . 72 , Here are the blow moldings 58 . 60 designed so that when the blow mold is closed 62 the blowhorn 70 the preform 54 and the blowhorn 72 the preform 56 is assigned respectively. After that, each of the blow spikes 70 . 72 Compressed air supplied to the preforms 54 . 56 inflation. The preforms adapt 54 . 56 the inner contour of the blow mold 62 on, causing the single chambers 12 . 14 be formed and welded to the touching surfaces and thus form the hollow body 10 ,

5 shows one for blowing one out of two preforms 54 . 56 existing hollow body 10 Device provided in the so-called batch process 50 , The illustration shows the position and the transformation of, from the preforms 54 . 56 resulting single chambers 12 . 14 in the blow mold 62 , The blow molding 58 is not shown here to give an insight into the closed blow mold 62 to enable. The preform 54 was made from an annular opening at the bottom 84 of the extrusion head 66 extruded while the preform 56 from an annular opening at the bottom 86 of the extrusion head 68 was extruded.

The two preforms 54 . 56 are in the blow mold 62 arranged and welded together on the respective sides facing each other. The welded sections form one in the hollow body 10 extending longitudinal ridge 16 , Each preform 54 . 56 and the individual chambers formed therefrom 12 . 14 is a blowhorn 70 . 72 assigned, by the compressed air 76 . 78 blown. In doing so, each of the preforms becomes 54 . 56 and every single chamber 12 . 14 compressed air at the same time 76 . 78 supplied with exactly the same pressure and with the same volume flow. Likewise, the vent after the completion of the blowing process at exactly the same time with the same volume flow from the individual chambers 12 . 14 to be done. This has the consequence that the hollow body 10 an outer wall with a over the surface of the hollow body 10 considered to have approximately uniform thickness, while the longitudinal ridge 16 has an approximately double compared to the outer wall thickness.

The representation after 5 further clarifies how the individual chambers 12 . 14 in the already closed blow mold 62 are arranged. It will be between the bottom of the extrusion heads 66 . 68 and the top 88 the blow mold 62 the slugs 80 . 82 educated.

6 shows a sectional view of a portion of the extrusion head 66 , the closed blow mold 62 , of the hollow body 10 and a Butzens 80 along the in 5 shown sectional plane CC, where in the 5 for better clarity not shown blow molding 58 is shown with. The slug 80 is a material overhang that will be removed later. Between the top 88 of the blow 62 and the bottom 84 of the extrusion head 66 was closing the blow mold 62 from the preform 54 the slug 80 separated. Between the bottom 84 and an outer wall of the Butzens 80 is an angle α.

This prevents the slug 80 during the closing of the blow mold 62 not on the extrusion head base 84 demolishes, a certain angle may not be fallen below. This angle depends on the melt-toughness of the preform 54 . 56 , It follows that with larger nozzle diameter and the distance between the extrusion head underside 84 and the blow mold top 88 grows larger and thus the proportion of Butzens 80 at the total length of the preform 54 increases and thus the performance of the device 50 adversely affected.

7 shows a schematic representation of a device 90 for producing a hollow body 122 consisting of the individual chambers 112 . 114 , The device 90 includes an extrusion device 92 , a first gripping device 94 for transporting the preforms 104 . 106 in the blow mold 120 , a second gripping device 96 for removing the finished blown hollow body 122 from the blow mold 120 , and a blowing device 98 ,

The extrusion device 92 includes two extrusion heads 100 . 102 , each of which is a preform 104 . 106 is extruded.

Here are the extrusion heads 100 . 102 arranged so that the preforms 104 . 106 do not touch.

The first gripping device 94 comprises two relatively movable grippers, each of the grippers transporting one of the preforms 104 . 106 into the blow mold. Are the preforms 104 . 106 Extruded, grab the gripper of the first gripping device 94 the preforms 104 . 106 Take them from the extrusion heads 100 . 102 take off and transport the preforms 104 . 106 to the blowing device 98 , During or after transport, the grippers move relative to each other and thereby change the distance of the preforms 104 . 106 from the distance of the extrusion heads 100 . 102 to the distance that the preforms 104 . 106 in the blowing device 98 to have.

While in the extrusion device 92 the preforms 104 . 106 are extruded, the last two extruded preforms 112 . 114 in the blowing device 98 according to the already related 5 blown method described. For this purpose, the blowing device comprises 98 two blow spines 116 . 118 and a blow mold comprising two blow moldings 120 , After blowing, the blow mold opens 120 along a mold parting plane and the second gripping device 96 takes the from the two preforms 112 . 114 resulting hollow body 122 , Subsequently, the first gripping device places 94 the preforms 104 . 106 between the blow moldings of the opened blow mold 120 what this closes and the blowing device 98 blows another hollow body.

8th shows a schematic representation of a device 124 for producing a hollow body in a further method. The device 124 includes an extrusion device 126 , a first gripping device 128 , a second gripping device 130 and a blowing device 132 ,

The blowing device 132 includes two blow pins 140 . 142 for blowing the preforms 136 . 138 to the hollow body and a separable on a mold parting plane, two blow molds comprehensive blow mold 144 ,

The extrusion device 126 includes an extrusion head 134 who is a preform 136 extruded in the direction of arrow P5. The previously extruded preform 138 was already from the first gripping device 128 from the extrusion head 134 removed, while closed and between the blow moldings of the open blow mold 144 brought. After extruding the preform 136 this is the second gripping device 130 from the extrusion head 134 removed and spaced from preform 138 between the blow moldings of the opened blow mold 144 arranged. Subsequently, the blow mold 144 closed and blown the preforms according to the method already described above to a single hollow body. After the subsequent opening of the blow mold 144 the hollow body produced is removed from the blow mold by a removal device, not shown.

Alternatively or additionally, a hose closing device can be provided which closes the preforms at their upper and at their lower end already before the closing of the blow mold. This may be necessary to stabilize the preforms by supplying supporting air, wherein the supply of the supporting air can be carried out in a known manner either via the extrusion heads or via blowing mandrels.

In the method described above as discontinuous, the extrusion heads are displaced along the mold parting plane. However, the displaceable extrusion heads may also extrude the preforms in other locations such that they are brought into juxtaposition within or outside the mold parting plane before being transferred between the opened blow moldings.

LIST OF REFERENCE NUMBERS

10, 122

hollow body

12, 14, 112, 114

Single chamber

16

longitudinal web

18, 20

face

22

front wall

24

rear wall

26, 28

inner space

30, 32, 34, 36, 38, 40

Vernapfung

42, 44

side surface

50, 90, 124

contraption

54, 56, 106, 106, 136, 138

preform

58, 60

Blow-Molded

62, 120, 144

blow

64

Parting plane

66, 68, 100, 102, 134

extrusion head

70, 72, 116, 118, 140, 142

mandrel

76, 78

compressed air

80, 82

slugs

84, 86

Extrusion head underside

88

Blasformoberseite

92, 126

extrusion device

94, 96, 128, 130, 140

gripping device

98, 132

blower

142, 144

grab

P1, P2, P3, P4, P5, P6, P7

arrows

α

angle

Claims (19)

Method for producing a hollow body ( 10 . 122 ) made of thermoplastic material by blow molding, with at least two blow molded parts ( 58 . 60 ) blow mold ( 62 . 120 . 144 ), wherein at least two freshly extruded preforms ( 54 . 56 . 104 . 106 . 136 . 138 ) in the open blow mold ( 62 . 120 . 144 ) are brought into juxtaposition, then the blow mold ( 62 . 120 . 144 ) and then the preforms ( 54 . 56 . 104 . 106 . 136 . 138 ) separated from each other in the blow mold ( 62 . 120 . 144 ) are blown at the same time, so that they become single chambers ( 12 . 14 . 112 . 114 ) are deformed and welded together at facing portions. Method according to claim 1, characterized in that at least two extrusion heads ( 66 . 68 . 100 . 102 ) are spaced apart and at the same time the preforms ( 54 . 56 . 104 . 106 ) extrude. Method according to claim 2, characterized in that the extrusion heads ( 66 . 68 ) above the blow mold ( 62 ) and that the preforms ( 54 . 56 ) are extruded along the mold parting plane. Method according to claim 2 or 3, characterized in that at least one extrusion head ( 66 . 68 ) is displaceably mounted, the preforms ( 54 . 56 ) with open blow mold ( 62 ) in the space between the blow moldings ( 58 . 60 ) are extruded and that the preforms ( 54 . 56 ) after extrusion by moving the movable extrusion heads ( 66 . 68 ) are brought into juxtaposition. Method according to claim 2, characterized in that a gripping device ( 94 ) at the same time the preforms ( 104 . 106 ) from the extrusion heads ( 100 . 102 ) and into the open blow mold ( 120 ) transport. Method according to claim 5, characterized in that the extrusion heads ( 100 . 102 ) are mounted displaceably. Method according to claim 5, characterized in that the gripping device ( 94 ) the distance of the preforms ( 104 . 106 ) during the transfer into the blow mold ( 122 ) changed each other. Method according to claim 1, characterized in that a gripping device ( 128 ) the preforms ( 136 ) successively from an extrusion head ( 134 ) and successively in the open blow mold ( 144 ). Method according to one of the preceding claims, characterized in that the hollow body produced ( 10 . 122 ) is a flat hollow body. Method according to one of the preceding claims, characterized in that each preform ( 54 . 56 . 104 . 106 . 136 . 138 ) with a separate mandrel ( 140 . 142 ) is blown. Method according to one of the preceding claims, characterized in that the hollow body ( 10 . 122 ) is cooled in the blow mold and thereby each preform ( 54 . 56 . 104 . 106 . 136 . 138 ), which becomes a single chamber ( 12 . 14 . 112 . 114 ) is formed, is subjected to the same gas pressure. Method according to one of the preceding claims, characterized in that the hollow body ( 10 . 122 ) with inside continuous webs ( 16 ) is formed with a wall thickness which is approximately twice as great as that of the outer wall. Method according to one of the preceding claims, characterized in that the produced hollow body ( 10 . 122 ) additionally with naps ( 30 to 40 ) is formed. Contraption ( 50 . 90 . 124 ) for producing a hollow body ( 10 . 122 ) made of thermoplastic material by blow molding, with at least two blow molded parts ( 58 . 60 ) blow mold ( 62 . 120 . 144 ), wherein at least two preforms ( 54 . 56 . 104 . 106 . 136 . 138 ) arranged by at least one in an initial position extrusion head ( 66 . 68 . 100 . 102 . 134 ) are extruded, are placed in the open blow mold in juxtaposition, the blow mold ( 62 . 120 . 144 ) is closed, the preforms ( 54 . 56 . 104 . 106 . 136 . 138 ) after closing the blow mold by supplying blown air ( 76 . 78 ) deform such that the Enzelkammern formed thereby ( 12 . 14 . 112 . 114 ) welded to facing portions, the preforms ( 54 . 56 . 104 . 106 . 136 . 138 ) are blown separately in the blow mold at the same time, such that the individual chambers ( 12 . 14 . 112 . 114 ) separated from each other in the blow mold ( 62 . 120 . 144 ) are simultaneously blown. Device according to claim 14, characterized in that the device ( 50 ) at least two extrusion heads ( 66 . 68 ), which above the blow mold ( 62 ) and in the mold parting plane ( 64 ) are positioned at a distance to each other which is approximately the center distance of the individual chambers ( 12 . 14 . 112 . 114 ) corresponds. Apparatus according to claim 14, characterized in that at least one of the extrusion heads ( 66 . 68 ) is displaceably mounted from a first position to a second position that in the second position, the extrusion heads ( 66 . 68 ) the preforms ( 12 . 14 . 54 . 56 ) are extruded such that the preforms ( 12 . 14 . 54 . 56 ) are spaced apart and that when closing the blow mold ( 62 ) the extrusion heads ( 66 . 68 ) are back in the first position. Device according to claim 14, characterized in that the device ( 90 ) at least two extrusion heads ( 100 . 102 ) that the extrusion heads ( 100 . 102 ) outside a movement space of the blow molded parts ( 58 . 60 ) and are arranged such that the extruded preforms ( 104 . 106 . 112 ) do not touch the device ( 90 ) at least one gripping device ( 94 ), wherein with the gripping device ( 94 ) all a hollow body ( 10 . 122 ) forming preforms ( 104 . 106 ) or a subset of preforms ( 104 . 106 ) are transported simultaneously to the open blow mold. Apparatus according to claim 17, characterized in that the gripping device ( 94 ) in the direction of movement of the preforms ( 104 . 106 ) the distance of the preforms ( 104 . 106 ) can change to each other. Device according to claim 14, characterized in that a device ( 126 ) with an extrusion head ( 134 ) a gripping device ( 128 . 130 ), wherein with the gripping device ( 128 . 130 ) the preforms ( 136 . 138 ) of a hollow body ( 10 . 122 ) are successively transported to the open blow mold.

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