DE102009022374A1 - Device for expanding plastic performs to plastic container, has blow mold which forms hollow space inside which plastic preforms are expanded, where blow mold has inner wall against which plastic preforms are expanded - Google Patents

Abstract

The device comprises a blow mold (2) which forms a hollow space (4) inside which plastic performs (10) are expanded. The blow mold has an inner wall (8) against which the plastic performs are expanded. An impingement device is provided for impinging the plastic performs with a medium. The areas (B1,B2) of the inner wall of the blow mold, are temperature controlled. An independent claim is also included for a method for expanding plastic performs to a plastic container.

Description

The The present invention relates to a device and a Method for producing plastic containers. Out In the prior art, current methods have long been known. In this case, plastic preforms, for example made of PET, which usually have circular cross sections, first heated and then inside a blow mold expanded to plastic containers. In the course of this expansion process these plastic containers are pressurized with compressed air, expanded in this way against the inner wall of the blow mold to become.

Partially However, plastic containers are required in the market, which do not have a circular cross section, but a different cross section, such as a oval basic shape. Also for producing such plastic containers Several methods are known from the prior art. So is For example, it is known that certain areas of the outer wall the plastic preforms are heated more strongly, so that they become stronger during the subsequent stretch blow molding process expand, making a total of one circular Cross-section deviating bottle shape arises.

This Operation is also known in the art as "preferential heating ".

From the JP 08174552 A is a blow molding known. In this case, heat-insulating reinforcing materials are used, so that the mold has a total of a double structure. Furthermore, heaters and water holes for cooling water are provided. The JP 63207630 A also describes a way to control a thickness in a circumferential direction of a bottle. Here also an elliptical blow mold is provided here.

From the US 4,380,526 For example, the apparatus and method for making non-cylindrical preform articles from PET is known. In this case, blow molds are used, which themselves have an elliptical cross section. The surface of the blow mold, against which the thermoplastic material is urged, can have an effect on the shaping along the main axis for non-round containers. For this purpose, it is proposed to apply a heat-insulating material in the region forming the container. This Teflon material is intended to improve the coefficient of friction with the plastic material of the plastic preform and reduce heat transfer from the material of the preform to the blow mold.

Of the The present invention is therefore based on the object, a device for expanding plastic preforms available which provides a simpler way to form also non-cylindrical, for example, oval, bottles offers.

This According to the invention by a device after Claim 1 and achieved by a method according to claim 13. Advantageous embodiments and further developments are Subject of the dependent claims.

A Inventive device for expanding Plastic preforms to plastic containers has a blow mold, which in turn forms a cavity, within of which the plastic preforms to plastic containers are expandable. Furthermore, the blow mold has an inner wall on, against which the plastic preforms are expanded and a loading device to the plastic preforms with a To apply medium to expand it. It is the Inner wall of the blow mold at least partially tempered.

According to the invention in a circumferential direction of the blow mold different areas the inner wall different temperature. It is therefore proposed according to the invention that within the blow mold different areas of the inner wall and preferably angle segments are tempered differently. It is possible, for example, that the "flat Sides of the blow mold at a higher temperature be held as the remaining form. In the blowing process comes the Preform (which preferably has a constant temperature) first on these flat sides to concerns. By the higher temperature of the blow mold in these segments cools the material does not degrade so quickly compared to a standard process.

On This way, the material can even continue on the flat sides be stretched, so that the production of, for example, oval containers is relieved. In contrast to known from the prior art Procedure is suggested that the oval shape of a first uniformly heated preform first generated during the actual expansion process. It is It is possible that it is the different temperature Areas around actively tempered areas, for example additionally heated or even the thermal damping media be used, which a fast heat dissipation prevent from said segments.

In addition, it would also be possible for different regions of the container surface coming to rest on the inner wall to differ are temperature controlled. It would thus be possible, for example, for small air holes to be provided in certain areas of the inner wall, through which heated air is directed onto the preform and in this area makes possible a greater stretching thereof. Through this air outlet and an air cushion can be formed, which facilitates stretching of the plastic material. The different temperature control can also be achieved by different materials on the surface of the inner wall of the blow mold.

Also would it be possible for that in certain areas the inner wall, in which a weaker draft should occur, cooled by the air holes Air meets the preforms. In addition, in certain Be arranged areas of the inner wall and radiation sources, which the material of the plastic preform with, for example Apply infrared radiation or microwave radiation, stronger around certain wall areas of the plastic preform to warm up.

at a preferred embodiment, the said cavity one deviating from a circular cross section Cross-section, for example an elliptical cross-section, on. This Cavity depends in particular on the shape of the produced Be ratio from and can be elliptical, for example be executed. In particular, the cavity in its Lengthwise at any point of the generating Bottle body one of a circular cross-section deviating cross-section on.

at a further advantageous embodiment, the Inner wall on a first area, the first predetermined radial distance to a longitudinal axis of the plastic preform as well as a second area that compares a second greater distance to the first predetermined distance to the longitudinal axis of the plastic preform, wherein the first area is warmed up more than that second area. As mentioned above, the plastic preforms become initially heated uniformly and then blow molded. Below the longitudinal axis of the plastic preform is understood in particular its symmetry axis, so that the distance of the plastic preform to the first area less is the distance of the plastic preform to the second region.

The said areas may have different temperature levels However, it would also be possible for the Temperature in the inner wall in the first region in the circumferential direction the inner wall changes to the temperature in the second area.

at a further advantageous embodiment, the Blow mold at least two separable Blasformsegmente on.

at a further advantageous embodiment, the Different temperable areas of the blow mold different Materials on. For example, in the stronger heated area, the first contacted by the blow mold is used, a material which has a low coefficient of friction with respect to the plastic of the preform. So For example, a Teflon material could be used in this area be used.

at a further advantageous embodiment, the Blow mold at least one channel to a medium for tempering the inner wall to guide through the blow mold. It serves this Channel prefers to be in the more heated Area to cause a higher warming. Instead of However, it would also be possible for a channel to be electrical Heating devices, such as heating resistors within to use the blow mold or its wall.

at a further advantageous embodiment, the Blow mold at least two separate channels for a tempering medium. So, in addition to the heating channel for the more heated areas also be used a cooling medium to the rest Cooling down areas of the blow mold. These chilled Inner walls are used in particular to a comparatively cause rapid solidification of the plastic preforms.

at a further advantageous embodiment, the Device on a vibration generating device, which a Relative vibration between the plastic preform and at least created a region of the blow mold. In particular, a relative vibration generated between the plastic preform and that area first, the plastic preform during its expansion touched. This vibration can stick to it Material of the plastic preform at the said area of Blow mold can be prevented. In this case, the vibration generating device be designed such that a vibration of said area, for example occurs in the longitudinal direction of the container, however, it would also be transversal and oscillations in the circumferential direction possible. The vibration generating device is preferably used an ultrasonic sonde or the like.

Preferably, the vibration generating means excites a portion of the inner wall the blow mold to swing. As mentioned, ultrasonic vibrations are preferably used. However, it would also be possible that the vibration generating means does not excite the blow mold, but the preform to vibrate. In particular, the region of the inner wall is excited to vibrate, which is contacted first.

It However, it should be noted that the vibration generating device described here also in connection with conventional blow molding, in particular Blow molding with uniformly tempered inner wall can be used.

at a further advantageous embodiment, the Device on an orientation device, which in terms of the plastic preform its rotational position with respect to its longitudinal axis oriented. In this case, such an orientation device of Blow mold upstream, so that the plastic preforms correctly oriented to get into this. Although, as mentioned, preferably the plastic preforms are evenly heated, However, however, a certain rotational position of the plastic preforms to comply with certain containers, for example also unscrew a screw cap on the container is and this in a certain direction on the container must sit. Therefore, the plastic preform is preferred in terms of aligned to its rotational position. Preferably, it is therefore possible the so-called neck alignment in containers with non-cylindrical Closures in the blowing module or in front of the blowing module in to perform a intermediate star. This will ensure the container shape fits the closure orientation.

at a further advantageous embodiment, the Blow mold within its wall a thermal insulating element on. In this case, this thermal insulating element is preferably behind the area of the wall, which is stronger in operation should be heated. By this insulating element is effected that in the said area heat worse to the blow mold is dissipated and thus this area is permanently warmer than the rest of the blow mold.

Farther it would be possible that on the inner wall of the Blow mold sections, an insulating layer is arranged. Also, this insulating layer can in particular in the stronger be provided heated area.

The The present invention is further directed to a plant for manufacturing directed by plastic containers, this attachment a device of the type described above and has a this device in the transport direction of the container preceding heater for heating the plastic preforms. Preferably, this heating device is designed such that the plastic preforms are evenly heated become.

at a further advantageous embodiment, the Plant in the direction of movement or transport direction of the plastic containers an orientation device on which the plastic preforms oriented in terms of their rotational position. Preferably, this is Orientation device between the heater and provided the forming device.

The The present invention is further directed to a method of expansion directed from plastic preforms to plastic containers, wherein the plastic preforms within a blow mold into plastic containers be expanded and wherein the plastic preforms against a Inner wall of the blow mold by applying a (preferably gaseous) medium are expanded. According to the invention different areas of the inner wall of the blow mold different tempered or different areas of the plastic preforms during the expansion process applied to different temperatures.

at Another preferred method will be used in some areas the plastic preforms introduced stiffening pattern.

Further Advantages and embodiments will be apparent from the attached Drawings:

In this demonstrate:

1 A schematic representation of an arrangement for expanding plastic containers;

2a - 2d four illustrations of a blow mold to illustrate a transformation process;

3 a representation of a blow mold according to the invention;

4 a further partial view of a blow mold according to the invention;

5a , b two illustrations of a blow mold according to the invention;

6a , b two illustrations of a blow mold according to the invention; and

7a . 7b two representations of another blow mold according to the invention.

1 shows a schematic representation of an arrangement 30 for expanding plastic preforms. This arrangement has a transport device or feeder shown only schematically 26 on which of the actual forming device 20 Containers. This may, for example, be a feed star. Another transport device or discharge device 28 serves to remove the formed plastic containers from the plant. At the forming device 20 is a plurality of devices according to the invention 1 or blowing stations 1 arranged, in each of which the plastic preforms are expanded to plastic containers. Each of these blowing stations points 1 a blow mold 2 within, within which the plastic preforms are reshaped. In addition, each of the individual blowing stations can 1 a stretch rod 22 have, which transforms the plastic preform into a plastic container or this stretches. The device 20 also has a rotatable (arrow P1) carrier 24 on where the individual blowing stations 1 are arranged. The reference sign 6 illustrates (roughly schematically) a loading device for the beating of the plastic preforms with air, such as a blowing nozzle.

Upstream (in the transport direction of the plastic preforms with respect to the forming device 20 has the arrangement 30 a heating device 32 for heating the plastic preforms. In this facility 32 the plastic preforms or at least their basic body are heated uniformly. In addition, an alignment device (not shown) may also be present, which aligns a rotational position of the plastic preforms along their longitudinal axis. This alignment device can, for example, on the feeder 26 but also already in the course of plastic preforms by the heater 32 be provided. The heater 32 can be designed for example as a passage furnace.

The 2a - 2d show four representations of a blow mold in the course of an expansion process. The basic idea of the present invention is that individual regions B1 of the blow mold are heated to a greater extent than other regions B2, these regions B1 being first touched during the expansion through the preform and premature freezing of the plastic material being prevented at this heated region, so that the Material still stretched into other areas.

In the in the 2a - 2d shown blow molds are each shown in black (heated) areas 12 more heated than the remaining areas B2. at 2a an illustration is shown in which a still undrawn plastic preform within a cavity 4 passing through the two blow mold halves 2a and 2 B is formed, is arranged. This will be within the entire blow mold 2 Angle segments or zones tempered differently in the circumferential direction. More specifically, the flat sides, ie, the areas B1, are maintained at a higher temperature than the remaining area of the blow mold 2 , As in 2 B shown, comes the plastic preform 10 in an expansion by compressed air first on these flat sides to concern. Due to the higher temperature of the blow mold in these areas B1, the material of the plastic preform cools 10 not so fast in these areas (cf. 2c ) and the material can also be further stretched on these flat sides.

The reference number 8th refers to an inner wall of the blow mold in its entirety, which, as mentioned above, is tempered differently in different regions in the circumferential direction. A mentioned Neckausrichtung the plastic preforms is used in particular for the production of bottles with non-cylindrical closures and is in the blowing module 20 or before the blowing module, for example, as mentioned in the feeder 26 completed. In this way it is ensured that the container shape also fits to its closure orientation.

At the in 2c As shown, the plastic preform is already almost completely expanded, which is also expressed by its now thinner wall. At the in 2d As shown, the plastic preform was completely against the inner wall 8th the blowing device expands. In this way, a uniform distribution of material during the actual blowing process is achieved by differently tempered mold segments. In this way it is possible for the heater 32 no changes are made, so that for expanding a uniformly tempered preform can be used. Furthermore, it would be possible for certain regions of the blow mold, in particular those regions, which the preform initially touches, ie the sections B1, to be vibrated. Thus, an ultrasonic sonde (not shown) could be used which would cause this particular area of the tuyere to vibrate. However, it would also be possible for the entire blow mold 2 or their halves to vibrations (relative to the plastic preform) are excited.

3 shows a possible representation of a blow mold according to the invention 2 , This blow mold 2 has separate fluid channels 18 respectively. 16 on. At the channels 16 These are cooling channels in which a liquid, as in For example, water flows, which has a comparatively low temperature, for example, a temperature between 10 ° and 20 ° Celsius. In other channels 18 can tile a tempering with a different temperature, for example, also water or oil with a temperature between 50 ° and 150 ° Celsius. In this way, the differently tempered area B1 and B2 within the blow mold 2 reached.

4 illustrates another variant to differently tempered areas within the blow mold 2 to reach. It would be possible, for example, an insulating or plastic layer 34 , like a Teflon layer, from the rear near the inner wall 8th the blow mold is introduced and cuts off a defined area of the blow mold from the heat dissipation to use.

A fine tuning would be possible by exchangeable inserts or insulating layers with different wall thicknesses. However, a supporting region of the surface B1 which is diluted in this region is preferably provided in order to increase the fatigue strength of the blow mold 2 in their entirety. Furthermore, it would be possible, a poorly thermally conductive material layer, such as a Teflon layer, on the surface of the inner wall 8th the form 2 B or to sink into the surface. In this case, however, the heat dissipation over different wall thicknesses would not be adjustable.

The Blow mold described here is both for the production of containers with oriented closures as well as for containers suitable with non-oriented closures. A Neckausrichtung or the orientation of the rotational position of the blow mold, for example be made so that means of image recognition via a camera is taken the mouth of the preform and from this image, the actual and target rotational position of the plastic preform is determined. As such "marking" can for example, the thread beginning of the thread of the plastic preform serve as the plastic preforms in these cases either have symmetrical threads that are not on it arrives, which start is in the front and which is behind or catchy threads, which in turn are unique.

In a further advantageous method, it would also be possible that the thin-walled areas by suitable container design measures such as grooves or other stiffening pattern at the distant points of the container ie in the 2a - 2d in the areas B2. In the context of the invention, however, in particular a damping of the cold quenching of the material in a first contact on the mold wall 8th proposed this damping, as described, active or passive, but in particular by partial tempering of the blow mold 2 is made in these places. In an active temperature control, as mentioned, an additional temperature control circuit is provided and in a passive temperature can also, as mentioned above, an additional temperature control by a localized in the blow mold 2 introduced material with poorer heat conduction than the rest of the blow mold 2 be made.

A Such passive temperature control could also be present Blow mold solutions are retrofitted and only in those cases where also a Neckausrichtung desired is, a corresponding module could be provided.

in the Trap of this passive solution can, as mentioned above, a vote of the heat conduction through the thickness of a introduced insulating layer can be controlled.

The 5a and 5b show a further embodiment of a blow mold according to the invention 2 , Here, a blow mold is shown, the interior of which is not oval but circular. However, this blow mold preferably also has a non-circular inner cross section. At the in 5a shown representation can be seen a heating element or a heating cartridge 42 which serves to heat a specific area of the inner wall in the circumferential direction of the blow mold. The reference number 18 in turn identifies a fluid channel for a heating medium

In this case, deviating from the illustration, two fluid channels 18 or two heating elements 42 be provided, or even these two heating systems are combined. The fluid channel has here in each case an inlet 18a and an expiry 18b on, with these inlets and outlets here perpendicular to the longitudinal direction L of the blow mold 2 extend. The fluid channel 18 extends as in 5a shown almost along the entire length of the blow mold 2 trained cavity 4 ,

The 6a and 6b show a further embodiment of a blow mold according to the invention. In this embodiment, in the blow mold halves 2a . 2 B in each case a vibration generating device 44 provided in the form of a sonotrode, which excites the blow mold halves to vibrate. In addition, it would also be possible to stimulate the blow molding frequencies not with ultrasound but with significantly lower frequencies, so that they vibrate. The inner wall 8th the blow mold 2 is here with a non-stick coating 48 Mistake.

The 6a and 6b show a further embodiment of a blow mold according to the invention. In this embodiment, in the wall of the blow mold 2 or the blow mold halves next to the temperature control channels 16 a plurality of air ducts provided through which a gaseous medium such as in particular air can be passed through the inner wall on the plastic preform. This creates during the blowing process, an air cushion, which also prevents material adheres to the inner wall of the blow mold early or early solidifies. In this case, heated air can be used, which is passed to the plastic preform.

This heated air can also cause heating of the plastic preform and thus promote a stretching of the same. In the in the 6a and 6b shown embodiment is a plurality of air ducts 52 provided, which the cavity 4 evenly surrounded in the circumferential direction. The reference number 54 refers to a plurality of feed channels which direct the gaseous medium from the air ducts to the plastic preforms.

However, it would also be possible for heated air to be conducted to the plastic preforms only in the areas in which they first touch the inner wall of the blow mold. The reference number 56 refers to a port to supply the gaseous medium to the air ducts. It would also be possible to provide a plurality of such terminals, which are distributed one behind the other in the longitudinal direction L, so as to promote the generation of a longitudinally uniform air cushion. Also, the cross sections of the air ducts could 52 vary in the longitudinal direction L, so as to bring about even discharge of the gaseous medium on the inner wall of the blow mold.

Also could have multiple connections 56 be distributed in the circumferential direction of the blow mold.

All Features disclosed in the application documents are considered to be essential to the invention as far as they are individually or in combination the prior art are new.

1

Contraption, blowing station

2

blow

2a, 2 B

blow mold halves

4

cavity

6

loading device

8th

inner wall the blow mold

10

Plastic preform

10a

wall of the plastic preform

12

heated areas

16

liquid channels for cooling medium

18

liquid channels for heating medium

18a, 18b

Supply and discharge of the liquid channel 18

20

shaping device

22

stretching rod

24

carrier

26

feeding

28

removal device

30

arrangement

32

heater

34

insulating

44

Vibrator

48

Anti-stick coating

52

Air ducts

54

supply channels

56

connection

B1, B2

areas

P1

arrow

L

longitudinal direction

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - JP 08174552 A [0004]
• JP 63207630 A [0004]
• US 4380526 [0005]

Claims (13)

Contraption ( 1 ) for expanding plastic preforms ( 10 ) to plastic containers, the device ( 1 ) a blow mold ( 2 ), which has a cavity ( 4 ) within which the plastic preforms ( 10 ) are expandable to plastic containers, and wherein the blow mold ( 2 ) an inner wall ( 8th ), against which the plastic preforms ( 10 ) are expanded with an impingement device ( 6 ) to pressurize the plastic preforms with medium to expand them, the inner wall ( 8th ) of the blow mold ( 2 ) is tempered at least in sections, characterized in that in a circumferential direction of the blow mold ( 2 ) different areas (B1, B2) whose inner wall ( 8th ) are different temperature. Device according to claim 1, characterized in that the cavity ( 4 ) has a different cross section from a circular cross-section. Device according to at least one of the preceding claims, characterized in that the inner wall has a first region (B1), which has a first predetermined radial distance to a longitudinal axis of the plastic preform ( 10 ), and a second region (B2) having a second distance, which is greater than the first predetermined distance, from the longitudinal axis of the plastic preform ( 10 ), and the first area is heated more than the second area. Device according to at least one of the preceding claims, characterized in that the blow mold ( 2 ) at least two separable Blasformsegmente ( 2a . 2 B ) having. Device according to at least one of the preceding Claims, characterized in that the different temperable areas of the blow mold different materials exhibit. Device according to at least one of the preceding claims, characterized in that the blow mold ( 2 ) has at least one channel to a medium for controlling the temperature of the inner wall by the blow mold ( 2 ). Device according to at least one of the preceding Claims, characterized in that the blow mold at least two separate channels for a tempering medium having. Device according to at least one of the preceding claims, characterized in that the device comprises a vibration generating device, which a relative vibration between the plastic preform and at least a portion of the blow mold ( 2 ) generated. Apparatus according to claim 8, characterized in that the vibration generating device ( 22 ) an area of the inner wall ( 8th ) of the blow mold to vibrate. Device according to at least one of the preceding Claims, characterized in that the device an orientation device comprising the plastic preform oriented with respect to a rotational position with respect to the longitudinal axis thereof. Device according to at least one of the preceding claims, characterized in that the blow mold ( 2 ) within its wall a thermal insulating element ( 24 ) having. Device according to at least one of the preceding claims, characterized in that on the inner wall ( 8th ) An insulating layer is arranged in sections. Method for expanding plastic preforms ( 10 ) to plastic containers, wherein the plastic preforms ( 10 ) within a blow mold ( 2 ) are expanded to plastic containers and wherein the plastic preforms ( 10 ) against an inner wall ( 8th ) of the blow mold ( 2 ) are expanded by application of a medium, characterized in that different regions (B1, B2) of the inner wall ( 8th ) of the blow mold ( 2 ) are tempered differently.