DE102005000681A1 - Thermoplastic container blow molding process involves heating tool parts with temperature control fluids at different temperatures and switching fluid flow between different tool areas - Google Patents

Abstract

During the blow molding stage the tool shells(5,6) and base part(7) are heated by at least two temperature control fluids at different temperatures. Flow of each temperature control fluid can be switched to heat or cool different areas of the tool. Switching(40) between the different temperature control fluids is performed either electrically or electropneumatically and the operation is monitored. Inner and outer shells and the tool base may be heated to different levels relative to each other. Various combinations of heating(48,49) and cooling(46,47) include: a) cooling the outer shells and base part while passively heating the inner shells; b) heating the outer shells and base to a temperature above that of the surrounding environment while passively cooling the inner shells; c) heating the outer and inner shells to a moderately warm temperature, e.g. 21-100[deg]C, while inner shells are heated to higher temperatures, e.g. 101-180[deg]C; d) cooling the base part while outer shells are heated to a moderately warm temperature and inner shells to a high temperature or e) inner shells are indirectly heated by contact with the outer shells. An independent claim is included for the blow molding plant each of whose blow molding tools are linked to a heating system with a fluid flow changeover valve(40). The latter unit is connected to two or more temperature control fluid supply lines at different temperatures and can switch(41,42;44,45) the different fluids to each part of a blow molding tool as required.

Description

The The invention relates to a method for the blow molding of containers, in a preform after a thermal conditioning within stretched a blow mold and formed by blowing pressure into the container as well as in the mold halves and a bottom part of the blow mold of at least two tempering agents different temperature can be controlled.

The Invention relates to this In addition, an apparatus for blow molding containers, the at least one Blowing station with a blow mold, as well as the blow mold with mold halves and a bottom part is provided and in which the blow mold to a Tempering device is connected.

at such a container molding by blowing pressure are preforms of a thermoplastic Material, for example PET preforms (polyethylene terephthalate), within a blow molding machine different processing stations fed. Typically, such a blow molding machine has a heating device and a blowing device, in the region of which previously tempered Preform expanded by biaxial orientation to a container becomes. The expansion takes place with the help of compressed air, which in the is initiated to expanding preform. The procedural Sequence in such an expansion of the preform is in the DE-OS 43 40 291 explained.

Of the fundamental Construction of a blowing station for container molding is described in DE-OS 42 12 583. Possibilities for tempering The preforms are described in DE-OS 23 52 926.

Within the blow molding apparatus, the preforms and the blown containers transported by means of different handling devices become. proven In particular, the use of transport thorns, to which the preforms are attached. But the preforms can be handled with other support devices. The usage grippers for handling preforms and use of expanding mandrels for mounting in a mouth region of the preform insertable are, belong also available Constructions.

A Handling of containers using transfer wheels For example, in DE-OS 199 06 438 in an arrangement of the transfer wheel between a blowing wheel and an output path.

The already explained Handling of the preforms takes place on the one hand in the so-called two-stage process, where the preforms initially in an injection molding process produced, then stored and later conditioned in temperature and inflated to a container become. On the other hand, an application in the so-called one-step process, in which the preforms immediately after their injection molding Manufacture and sufficient solidification suitable tempered and subsequently be inflated.

in the With regard to the blowing stations used are different embodiments known. At blow stations, which are arranged on rotating transport wheels are, a book-like Aufklappbarkeit the mold carriers are frequently encountered. But it is also possible to use relatively displaceable or differently guided mold carriers. at fixed blow molding stations, which are particularly suitable for multiple cavities for container molding are typically arranged parallel to each other Plates as mold carriers used.

Frequently it is necessary to cool and / or heat the tools used. For this purpose, the support wheel appropriate tempering via rotary joints or rotary distributor supplied. Especially with a required use of tempering with different temperatures are the rotary distributors used designed as comparatively complex and expensive components, the at a larger number from connected processing stations under consideration the required line connections also a considerable amount of space taking.

task It is the object of the present invention to provide a method of the mentioned type to improve such that a simplified constructive Structure and a simplified operation are supported.

These Task is inventively characterized solved, that the Blow mold at least partially switchable from one each the tempering is tempered.

Further Object of the present invention is to provide a device of initially mentioned type to construct such that a resource supply the carrying wheel is simplified.

This object is achieved in that the tempering device has a switching device with at least two Temperiermittelversorgungen different temperature is connected and controllably connects at least a portion of the blow mold with one of the Temperiermittelversorgungen.

By the controllability and switchability of the tempering is it is possible without the implementation of assembly operations each needed To provide temperature control in the blow mold. If necessary Rotary distributors used are only those tempering of the blow mold supplied the for a concrete application case actually needed. In particular thought, the switching of the temperature control in dependence operator inputs in the area of a control of the blow molding machine.

Preferably selects Operator of the machine in the area of a control and operating device only the product to be manufactured and the controller then leads all Adjustments in the Area of the switching device and the tempering automatically and without further assistance from the operator.

A simple operability is supported by the fact that the switching of the tempering is electrically controlled.

A Another control variant is that the switching of the tempering is controlled electropneumatically.

to increase the operational reliability becomes suggested that a function monitoring carried out becomes.

A adaptability to different product requirements is provided by that the Blow mold forming inner shells, outer shells and the bottom part be tempered differently relative to each other.

to Production of standard bottles proves to be advantageous that the Outer shells as well the bottom part cooled and that the Inner shells are only passively tempered.

to Production of bottles with increased temperature resistance It is suggested that the outer shells and the bottom part at a temperature level above an ambient temperature be tempered and that the Inner shells are only passively tempered.

A Production of heat-resistant Bottles are supported by that the outer shells and the bottom part is warm and the inner shells are kept hot.

A another operating variant is that the bottom part is cooled, the outer shells warm and the inner shells are kept warm become.

To a simple structural design, it helps that the inner shells indirectly by heat-conducting Contact with the outer shells be tempered.

A very robust technical realization is provided by that the Switching device formed from at least one 3-2-way ball valve is.

To an individually predetermined temperature distribution during manufacture different containers wear it in that the Blow mold from outer shells, Inner shells and a bottom part is formed.

A easy connection to the Temperiermittelversorgungen is achieved in that the switching device stationary next to a rotatable mounted blowing wheel is arranged.

In The drawings are exemplary embodiments of the invention shown schematically. Show it:

1 A perspective view of a blowing station for the production of containers from preforms,

2 a longitudinal section through a blow mold, in which a preform is stretched and expanded,

3 a sketch to illustrate a basic structure of a device for blow molding containers,

4 a modified heating section with increased heating capacity and

5 a schematic diagram for illustrating the operation of a switching device of the temperature control for two optionally supplied temperature control.

The basic structure of a device for forming preforms ( 1 ) in containers ( 2 ) is in 1 and in 2 shown.

The device for forming the container ( 2 ) consists essentially of a blowing station ( 3 ), which are blown ( 4 ) into which a preform ( 1 ) can be used. The preform ( 1 ) can be an injection-molded part of polyethylene terephthalate be lat. To enable insertion of the preform ( 1 ) in the blow mold ( 4 ) and to allow removal of the finished container ( 2 ) the blow mold ( 4 ) from mold halves ( 5 . 6 ) and a bottom part ( 7 ), which by a lifting device ( 8th ) is positionable. The preform ( 1 ) in the area of the blowing station ( 3 ) of a transport mandrel ( 9 ), which together with the preform ( 1 ) passes through a plurality of treatment stations within the device. But it is also possible to use the preform ( 1 ), for example via pliers or other handling means directly into the blow mold ( 4 ).

To enable a compressed air supply line is below the transport mandrel ( 9 ) a connecting piston ( 10 ) disposed of the preform ( 1 ) Supplies compressed air and at the same time a seal relative to the transport mandrel ( 9 ). In a modified construction, it is basically also conceivable to use solid compressed air supply lines.

A stretching of the preform ( 1 ) takes place with the aid of a stretching rod ( 11 ), by a cylinder ( 12 ) is positioned. Basically, it is also conceivable, a mechanical positioning of the stretch rod ( 11 ) via curve segments that are acted upon by Abgriffrollen. The use of curve segments is particularly useful when a plurality of blow molding stations ( 3 ) are arranged on a rotating blowing wheel. A use of cylinders ( 12 ) is useful when stationarily arranged blow molding stations ( 3 ) are provided.

At the in 1 illustrated embodiment, the stretching system is designed such that a tandem arrangement of two cylinders ( 12 ). From a primary cylinder ( 13 ), the stretch rod ( 11 ) first before the beginning of the actual stretching process into the area of a soil ( 14 ) of the preform ( 1 ) hazards. During the actual stretching process, the primary cylinder ( 13 ) with extended stretch rod together with a primary cylinder ( 13 ) carrying carriages ( 15 ) from a secondary cylinder ( 16 ) or via a cam control. In particular, the secondary cylinder ( 16 ) such a cam-controlled use that of a leadership role ( 17 ), which slides along a curved path during the execution of the stretching process, a current stretching position is specified. The leadership role ( 17 ) is from the secondary cylinder ( 16 ) pressed against the guideway. The sled ( 15 ) slides along two guide elements ( 18 ).

After closing in the range of girders ( 19 . 20 ) arranged mold halves ( 5 . 6 ) there is a locking of the carrier ( 19 . 20 ) relative to each other by means of a locking device ( 40 ).

For adaptation to different shapes of a mouth section ( 21 ) of the preform ( 1 ) is according to 2 the use of separate thread inserts ( 22 ) in the area of the blow mold ( 4 ) intended.

2 shows in addition to the blown container ( 2 ) also shown in dashed lines the preform ( 1 ) and schematically a developing container bubble ( 23 ).

3 shows the basic structure of a blow molding machine with a heating line ( 24 ) and a rotating blowing wheel ( 25 ) is provided. Starting from a preform input ( 26 ), the preforms ( 1 ) of transfer wheels ( 27 . 28 . 29 ) in the area of the heating section ( 24 ). Along the heating route ( 24 ) are radiant heaters ( 30 ) as well as blowers ( 31 ) arranged to the preforms ( 1 ) to temper. After a sufficient temperature of the preforms ( 1 ) these are to the blowing wheel ( 25 ), in whose area the blowing stations ( 3 ) are arranged. The finished blown containers ( 2 ) are provided by further transfer wheels of a delivery line ( 32 ).

To get a preform ( 1 ) into a container ( 2 ) that the container ( 2 ) Has material properties which have a long useful life from inside the container ( 2 ), in particular beverages, special process steps in the heating and orientation of the preforms ( 1 ) be respected. In addition, advantageous effects can be achieved by adhering to special dimensioning regulations.

When thermoplastic material can different plastics are used. Can be used for example PET, PEN or PP.

The expansion of the preform ( 1 ) during the orientation process is carried out by compressed air supply. The compressed air supply is in a Vorblasphase in which gas, for example, compressed air, is supplied at a low pressure level and divided into a subsequent Hauptblasphase in which gas is supplied at a higher pressure level. During the pre-blowing phase, compressed air is typically used with a pressure in the interval of 10 bar to 25 bar and during the main blowing phase compressed air is supplied at a pressure in the interval of 25 bar to 40 bar.

Out 3 is also apparent that in the illustrated embodiment, the heating section ( 24 ) from a plurality of circulating transport elements ( 33 ) is formed, the chain-like aneinan strung along and along pulleys ( 34 ) are guided. In particular, it is envisaged to open a substantially rectangular basic contour by the chain-like arrangement. In the illustrated embodiment, in the region of the transfer wheel ( 29 ) and an input wheel ( 35 ) facing the extent of the heating section ( 24 ) a single relatively large-sized deflection ( 34 ) and in the region of adjacent deflections two comparatively smaller dimensioned deflection wheels ( 36 ) used. In principle, however, any other guides are conceivable.

To enable a dense arrangement of the transfer wheel ( 29 ) and the input wheel ( 35 ) relative to each other, the arrangement shown to be particularly useful, since in the region of the corresponding extent of the heating section ( 24 ) three deflection wheels ( 34 . 36 ), in each case the smaller deflection wheels ( 36 ) in the area of the transition to the linear curves of the heating section ( 24 ) and the coarser diverting wheel ( 34 ) in the immediate transfer area to the transfer wheel ( 29 ) and to the input wheel ( 35 ). Alternatively to the use of chain-like transport elements ( 33 For example, it is also possible to use a rotating heating wheel.

After a finished blowing of the container ( 2 ), these are picked up by a picking wheel ( 37 ) from the field of blowing stations ( 3 ) and via the transfer wheel ( 28 ) and an output wheel ( 38 ) to the output section ( 32 ).

In the in 4 illustrated modified heating section ( 24 ) can by the larger number of radiant heaters ( 30 ) a larger amount of preforms ( 1 ) are tempered per unit time. The blowers ( 31 ) direct cooling air into the area of cooling air ducts ( 39 ), which the associated radiant heaters ( 30 ) in each case opposite and deliver the cooling air via outflow openings. Due to the arrangement of the outflow directions, a flow direction for the cooling air is substantially transverse to a transport direction of the preforms ( 1 ) realized. The cooling air channels ( 39 ) in the area of the radiant heaters ( 30 ) opposite surfaces provide reflectors for the heating radiation, it is also possible on the discharged cooling air and a cooling of the radiant heater ( 30 ) to realize.

5 shows a schematic diagram for a Temperiermittelumschaltung using a switching device ( 40 ). In the illustrated embodiment, the switching device ( 40 ) pneumatically controllable and control valves ( 41 . 42 ) are connected to a pneumatic actuator ( 43 ) connected. The control valves ( 41 . 42 ) are equipped with main valves ( 44 . 45 ) connected to a Temperiermittelzufuhr the blow mold ( 4 ) Taxes. The switching device ( 40 ) has connections ( 46 . 47 ) for the supply and discharge of a first temperature control and connections ( 48 . 49 ) for the supply and discharge of a second temperature control. The first temperature control means can be used for cooling and the second temperature control means for heating or cooling the blow mold ( 4 ) be used.

For the implementation of cold and warm tempering water is preferably used. An implementation the hot ones Tempering is preferably carried out using oil. Under one cold tempering here is a temperature in a temperature range from about 10 to 20 degrees Celsius. The term of warm tempering takes place in a temperature range of about 21 to 100 degrees Celsius. Under a hot tempering is understood a temperature range of about 101 to 180 degrees Celsius.

The valves ( 44 . 45 ) can be designed as pneumatically controlled 3-2-way ball valves.

According to one variant becomes a third circuit for the hot oil separately and not over guided the switching valves. This temperature control is used to heat the blow mold.

Claims (16)

A process for the blow molding of containers, in which a preform is stretched after a thermal conditioning within a blow mold and formed by blowing pressure into the container and in the mold halves and a bottom part of the blow mold of at least two temperature control means of different temperature are tempered, characterized in that the blow mold ( 4 ) is at least partially switchable tempered by one of the tempering. Method according to claim 1, characterized in that that the Switching the temperature control media is electrically controlled. Method according to claim 1, characterized in that that the Switching the temperature control media is controlled electropneumatically. Method according to one of claims 1 to 3, characterized that one function monitoring carried out becomes. Method according to one of claims 1 to 4, characterized in that the blow mold ( 4 ) forming inner shells, outer shells and the bottom part ( 7 ) are tempered differently relative to each other. Method according to one of claims 1 to 5, characterized in that the outer shells and the bottom part ( 7 ) are cooled and that the inner shells are only passively tempered. Method according to one of claims 1 to 5, characterized in that the outer shells and the bottom part ( 7 ) are tempered at a temperature above an ambient temperature and that the inner shells are tempered only passively. Method according to one of claims 1 to 5, characterized in that the outer shells and the bottom part ( 7 ) warm and the inner shells are kept hot. Method according to one of claims 1 to 5, characterized in that the bottom part ( 7 ) is cooled, the outer shells warm and the inner shells are heated hot. Method according to one of claims 1 to 5, characterized that the Inner shells indirectly by heat-conducting Contact with the outer shells be tempered. Apparatus for blow-molding containers, which has at least one blowing station with a blow mold, and in which the blow mold is provided with mold halves and a bottom part and in which the blow mold is connected to a tempering device, characterized in that the tempering device is a switching device ( 40 ), which is connected to at least two Temperiermittelversorgungen different temperature and the at least a portion of the blow mold ( 4 ) controllably connects with one of the Temperiermittelversorgungen. Apparatus according to claim 11, characterized in that the switching device ( 40 ) is electrically controllable. Apparatus according to claim 11, characterized in that the switching device ( 40 ) is formed electropneumatically controllable. Device according to one of claims 11 to 13, characterized in that the switching device ( 40 ) is formed from at least one 3-2-way ball valve. Device according to one of claims 11 to 14, characterized in that the blow mold ( 4 ) of outer shells, inner shells and a bottom part ( 7 ) is trained. Device according to one of claims 11 to 15, characterized in that the switching device ( 40 ) stationary next to a rotatably mounted blowing wheel ( 25 ) is arranged.