DE10141639A1 - Thermoplastic blank tempering comprises using a heat radiating unit which has electrical connections, a carrier and a reflector - Google Patents

Abstract

An arrangement for tempering thermoplastic blanks, comprises a heat radiating unit which has electrical connections for energy supply, and which is held in a carrier. A reflector (22) is located opposite the heat radiating unit, and consists of a plate type middle section (65) and at least two plate type side sections (60,67). The side sections are at an angle of 20-40 degrees to the central section. The reflector has a coating which either increases or decreases wavelengths and the coating is located near the middle section.

Description

The invention relates to a device for Tempering of preforms from one thermoplastic material containing at least one Has radiant heater with electrical connections provided for energy supply and by a carrier is supported and at the opposite to Radiant heater a reflector is arranged.

Such devices are used in particular in the Manufacture of blow molded containers used to one for carrying out the blowing process and for the Achieve an optimal material distribution To achieve tempering of the preforms.

With such a container formation Blast pressure effects are preforms from one thermoplastic material, for example preforms made of PET (polyethylene terephthalate), within one Blower module different processing stations fed. Typically, such a Blower module a heater and a Blower device, in the area of which previously tempered preform through biaxial orientation to one Container is expanded. The expansion takes place with Using compressed air to expand into the Preform is initiated. The procedural Procedure for such an expansion of the preform is explained in DE-OS 43 40 291.

Within the blow module, the preforms can as well the blown containers with the help of different Handling devices are transported. Known is for example the use of transport mandrels, onto which the preforms are placed. The Moldings can also be used with others Carriers are handled. The use of Gripping pliers for handling preforms described for example in FR-OS 27 20 679. On Expanding mandrel, which is used for holding in a mouth area of the preform is insertable in the WO 95 33 616 explains.

The shaping of preforms already explained Containers are made on the one hand with the so-called Two-step process in which the preforms first manufactured in an injection molding process, then temporarily stored and only later conditioned in terms of their temperature and too inflated in a container. On the other hand such a transformation in the so-called One-step process in which the preforms immediately after their injection molding manufacture and sufficient consolidation tempered and then inflated.

Both in the two-stage process and in the One step processes are used to temper the Preforms before blow molding heaters used, which have tubular radiant heaters. This is usually an infrared Spotlights, because such spotlights are technically simple are controllable and the infrared radiation with good Efficiency is absorbed by the preforms. The preforms are typically made at one such heating on the fixed installed Radiant heaters passed. Due to the Part of the radiant pattern of the radiant heater reaches the emitted heat radiation does not affect the preforms, but gets into an environment. This reduces the achievable efficiency. To improve the Efficiency is already from DE-OS 24 06 955 known, opposite to the radiant heaters Arrange reflectors that correspond to one half of a cylinder wall are contoured. The DE-OS 24 27 611 also describes the construction of arched Reflectors.

The use of such reflectors could However, do not enforce it in practice, since hoped increase in efficiency at Heating was reached.

The object of the present invention is a Device of the type mentioned in the introduction construct that improved energy efficiency is achieved when the preforms are heated.

This object is achieved in that the reflector is a plate-like and located in essentially extending parallel to the radiant heater Middle part and at least two plate-like and at least in some areas at an angle to the middle section has extending side panels.

The use of angled relative to each other oriented plate-like reflectors leads to a significant improvement in efficiency at Heating. The reflectors can also be used inexpensive to manufacture, especially because of this is, the middle part and the side parts in one piece produce and by appropriate bends transfer into each other. The construction of the Reflectors from the middle part and the side parts proves itself especially in the implementation of the One-step procedure as advantageous, since here the Preforms are moved in cycles and at least the predominant part of the period of their heating in Focus of the respective reflector positioned can be.

An advantageous distance between the heater and the reflector can be achieved in that the Side parts relative to the middle part with an angle in Range from 20 ° to 40 °.

In particular, it is thought that the angle of inclination is about 30 °.

This leads to a structurally simple implementation supports that the middle part is a flat plate spans.

It also contributes to a simple constructive Design at least one of the side panels clamps a flat plate.

To adapt to the rounded contour of the preforms it is also possible that at least one of the Side panels spanned a curved plate.

Another design variant is that at least one of the side parts made of plate-like Segments is formed.

A further improvement in efficiency can can be achieved in that the reflector at least in some areas a coating for Has wavelength transformation.

For example, it is possible that the coating a substance to lengthen the wavelength having.

Another frequency component can be used be that the coating is a substance for Shortening the wavelength.

A further improvement in energy yield can can be achieved in that the coating both a substance for shortening the wavelength as well a substance to lengthen the wavelength having.

To ensure a possible transformation large proportion of radiation in the area well from thermoplastic material of absorbable wavelengths it is proposed that the coating be a substance has only in a selective frequency range the wavelength of the radiation changes.

A typical application is that the Reflector in the area of a heating section single-stage device for container formation is.

It is also contemplated that the reflector in Area of a heating section of a two-stage Device for container formation is arranged.

An optimization of the reflection behavior in Dependence on a typical design of the Preforms can be achieved in that the Middle part has a width that is about one Outside diameter of the preform to be tempered equivalent.

A wavelength transformation already through that to be warmed. Material that has passed through Radiation components are supported in that the Coating is arranged in the region of the middle part.

In the drawings, embodiments of the Invention shown schematically. Show it:

Fig. 1 is a schematic diagram of a plan view of an apparatus for molding containers using the one-step process,

Fig. 2 is a schematic representation of a side view of a transfer device which is arranged between an injection module and a blowing module,

Shows a side view of a blow station, be inflated in the preforms with their openings facing upwards to containers. 3,

Fig. 4 shows a longitudinal section through a blow mold in which a parison is stretched and expanded,

Fig. 5 is a perspective view of a heating device with several tubular radiant heaters and opposite reflector and

Fig. 6 is a plan view according to the viewing direction VI in Fig. 5.

The device for temperature control can be used, for example, when the one-step process is implemented. The basic structure of such a single-stage device using an injection molding module ( 1 ) and a blowing module ( 2 ) is shown in Fig. 1.

The embodiment of a single-stage device for container forming shown in FIG. 1 has an injection molding module ( 1 ) and a blow module ( 2 ), which are connected to one another by a transfer device ( 3 ). The injection molding module ( 1 ) is equipped with an extruder ( 4 ) and an injection mold ( 5 ), in the area of which a plurality of cavities ( 6 ) for the production of preforms ( 7 ), not shown in FIG. 1, are arranged.

The blow module ( 2 ) is provided with a plurality of mounting elements ( 8 ) which can be transported along a closed circulation path ( 9 ). The holding elements ( 8 ) are fed to a blowing station ( 10 ), in the area of which the preforms ( 7 ) are deformed relative to one another into containers ( 11 ), not shown. A distance from the longitudinal axes ( 12 ) of the preforms ( 7 ) relative to one another is greater in the area of the blowing station ( 10 ) than in at least one other area of the circulation path ( 9 ).

In order to carry out the change in distance of the longitudinal axes ( 12 ) of the preforms ( 7 ), a distance between the holding elements ( 8 ) is changed relative to one another. This change in distance can be carried out with the aid of a distance modifier ( 13 ), which according to the embodiment in FIG. 1 is provided with a spiral-like profile ( 14 ). In the embodiment shown, the spiral profile ( 14 ) is designed as a groove in a shaft ( 15 ) which is connected to a drive ( 16 ) for specifying a rotational movement. The drive ( 16 ) can be coupled to the shaft ( 15 ) via a gear ( 17 ).

When using a shaft ( 15 ) with a groove-like profile ( 14 ), the holding elements ( 8 ) are advantageously provided with guide elements ( 18 ) which engage in the profile ( 14 ). The guide elements ( 18 ) can be formed, for example, from laterally projecting bolts which carry cam rollers ( 19 ).

The combination of the injection molding module ( 1 ), the blowing module ( 2 ) and the transfer device ( 3 ) provides a so-called one-step device for blow molding containers ( 11 ), in which the preforms ( 7 ) from the injection molding module ( 1 ) to the blowing module ( 2 ) be transferred at a temperature that is above the ambient temperature. It is therefore not necessary in the area of the blow module to heat the preforms ( 7 ) from an ambient temperature to the blow temperature, but only a suitable temperature modification or temperature profile is required in the area of a temperature control section ( 20 ). For this purpose, the temperature control section ( 20 ) has heating devices ( 21 ) which can be equipped, for example, with infrared radiators. To improve the utilization of the applied heating energy, reflectors ( 22 ) are used. In the embodiment shown, the reflectors ( 22 ) have a reflector profile ( 23 ) which is adapted to the external design of the preforms ( 7 ). The reflectors ( 22 ) can be positioned transversely to the circulation path ( 9 ) in order to support the closest possible arrangement on the preforms ( 7 ).

The support elements ( 8 ) are transported along the circulation route ( 9 ) in cycles with successive standstill phases and transport phases. The function of the transfer device ( 3 ), the positioning of the reflectors ( 22 ) and the rotational movement of the distance modifier ( 13 ) are adapted to the respective movement cycle. A conveyor of the holding elements (8) along the circulation path (9) can be effected for example by means of a driven sprocket (24) having a profile (25) for acting on the holding elements (8) and preferably in the region of a deflection of the circulation path (9) is arranged.

The cycle operation of the blow module ( 2 ) is controlled in such a way that a larger number of preforms ( 7 ) can be produced in the area of the injection molding module ( 1 ) than are subsequently simultaneously formed into containers ( 11 ) in the area of the blow module ( 2 ). For example, in the variant shown, it is intended to produce ten preforms ( 7 ) simultaneously in the area of the injection molding module ( 1 ) and in the area of the blowing station ( 10 ) from the ten preforms ( 7 ) to five containers ( 11 ) in five successive cycle cycles to produce.

Another variant consists in producing five preforms ( 7 ) simultaneously in the area of the injection molding module ( 1 ) and in the area of the blowing station ( 10 ) producing a container ( 11 ) from these five preforms ( 7 ) in five successive cycle cycles.

Fig. 2 illustrates in a side view the structure of the transfer device ( 3 ). In particular, it can also be seen that the injection mold ( 5 ) is formed from a cavity block ( 26 ) and from injection molding cores ( 27 ) which can be positioned relative to the cavity block ( 26 ) by a lifting device ( 28 ). After a sufficient thermal solidification of the preforms ( 7 ) within the injection mold ( 5 ), the preforms ( 7 ) are raised together with the injection molding cores ( 27 ) and a support element ( 29 ) of the transfer device ( 2 ) can be moved into the area of the injection molding module ( 1 ) retract. The preforms ( 7 ) are then inserted into transport recesses ( 30 ) in the support element ( 29 ). This takes place, if necessary, after opening the mouth molds ( 31 ) and to facilitate stripping off the injection-molded cores ( 27 ) with compressed air support or using suitable stripping or ejection devices.

The support element ( 29 ) is carried by an adjusting device ( 32 ) which is arranged displaceably along a guide ( 33 ). After the support element ( 29 ) has been moved, the support element ( 29 ) is raised by the adjusting device ( 32 ) so that the preforms ( 7 ) can be acted upon by the mounting elements ( 8 ).

The support elements ( 8 ) are guided along the circulation path ( 9 ) by rails ( 34 ). In the area of the blowing station ( 10 ), a connecting piston ( 35 ) can be lowered, through which a pressurized medium for expanding the preforms ( 7 ) can be passed through the holding element ( 8 ) into the preforms ( 7 ).

Fig. 3 shows a side view of the blowing station ( 10 ). The blowing station ( 10 ) is provided with mold carriers ( 36 , 37 ) which each hold blow mold segments ( 38 , 39 ). The mold carriers ( 36 , 37 ) together with the blow mold segments ( 38 , 39 ) can be adjusted transversely to the circulation path ( 9 ) in order to be able to carry out opening and closing movements. In the embodiment shown, the mold carriers ( 36 , 37 ) are positioned with the aid of pivoting levers ( 40 ) which are pivotably mounted in the region of a base plate ( 41 ). The pivot levers ( 40 ) have main bearings ( 42 ) for connection to the base plate ( 41 ). A connection to the mold carriers ( 36 , 37 ) takes place via swivel joints ( 43 ), a connection to a positioning element ( 44 ) takes place via swivel joints ( 45 ).

The positioning element ( 44 ) can be adjusted in the vertical direction along a guide ( 46 ). The adjustment can take place, for example, with the aid of a threaded rod ( 47 ) which is set in rotation by a drive ( 48 ). When the positioning element ( 44 ) is raised, the blowing station ( 10 ) is opened, and when the positioning element ( 44 ) is lowered, the blowing station closes.

From Fig. 3 it can also be seen that a lifting device ( 49 ) is used for positioning the connecting piston ( 35 ), which has a drive ( 50 ). The lifting device ( 49 ) has guide elements ( 51 ) for a transport carriage ( 52 ) which holds the connecting piston ( 35 ). The adjustment movement can be transmitted, for example, via a drive belt ( 53 ).

Fig. 4 shows schematically within the blowing station ( 10 ) in addition to the blown container ( 11 ) in dashed lines the preform ( 7 ) and a developing container bladder ( 54 ). The preform ( 7 ) or the container ( 11 ) can be held within the blow molding station ( 10 ) by a threaded insert ( 55 ) and a stretching rod ( 56 ) is used to stretch the preform ( 7 ). The threaded insert ( 55 ) holds a mouth region ( 57 ) of the preform ( 7 ) and the stretching rod ( 56 ) exerts pressure on a bottom ( 58 ) of the preform ( 7 ) while the stretching process is being carried out during the feed movement. The blow mold ( 10 ) can be provided with a base insert ( 60 ) in order to enable the shape of a container base ( 59 ) with contour undercuts.

Different thermoplastic materials can be used Plastics are used. Are operational for example PET, PEN or PP.

The preform ( 7 ) expands during the orientation process by supplying compressed air. The compressed air supply is divided into a pre-blowing phase, in which gas, for example compressed air, is supplied at a low pressure level and into a subsequent main blowing phase, in which gas is supplied at a higher pressure level. Compressed air with a pressure in the interval from 10 bar to 25 bar is typically used during the pre-blowing phase and compressed air with a pressure in the interval from 25 bar to 40 bar is fed in during the main blowing phase.

Fig. 5 shows an enlarged and perspective view of the heating device ( 21 ). In the area of a support frame ( 61 ), a plurality of tubular radiant heaters ( 62 ) are arranged one above the other in the vertical direction, which are received by mounting blocks ( 63 ) in the area of their ends. The radiant heaters ( 62 ) are preferably made of quartz glass and the mounting blocks ( 63 ) can be made of ceramic. Heating coils ( 64 ) run through the radiant heaters ( 62 ) and are electrically contacted in the area of the mounting blocks ( 63 ).

The reflector ( 22 ) is arranged opposite the radiant heaters ( 62 ). The reflector ( 22 ) has a plate-like middle part ( 65 ) and two plate-like side parts ( 66 , 67 ). The middle part ( 65 ) extends essentially parallel to a plane spanned by the radiant heaters ( 62 ), the side parts ( 66 , 67 ) run obliquely to this plane. The side parts ( 66 , 67 ) and the middle part ( 65 ) together span three boundary lines of a trapezoidal base.

In the embodiment shown, the side parts ( 66 , 67 ) have an inclination relative to the central part ( 65 ) of approximately 30 °. The side parts ( 66 , 67 ) are realized in this embodiment as a flat plate. In principle, it is also conceivable for the side parts ( 66 , 67 ) to be curved, in particular with the intention of realizing a curvature in the direction of the radiant heaters ( 62 ) starting from the central part ( 65 ). In addition, it is also contemplated to realize the side parts ( 66 , 67 ) from individual segments, which can each be made from flat plates and / or from curved plates.

Fig. 6 shows a preform ( 7 ) which is arranged between the radiant heaters ( 62 ) and the reflector ( 22 ). In particular, a beam path ( 68 ) is shown in FIG. 6, which illustrates how the essential portion of the heating radiation spreads. From Fig. 6 it can also be seen that a certain proportion of the heating radiation is reflected in the area of a surface ( 69 ) of the preform and is reflected back into the area of the radiant heater ( 62 ). Another portion of the heating radiation penetrates the preform and is thrown back in the direction of the preform ( 7 ), in particular in the region of the central part ( 65 ) of the reflector ( 22 ).

The main reason for penetration of the preform ( 7 ) by the heating radiation is that the radiant heaters ( 62 ) emit the heating radiation with different radiation frequencies and that the material of the preform ( 7 ) has an absorption behavior for the heating radiation depending on the respective wavelength , Since poorly absorbed wavelengths can penetrate the preform ( 7 ) even after a new reflection, particular consideration is given to providing the reflector ( 22 ) with a coating ( 70 ) at least in certain areas, which changes the wavelength when the heating radiation is reflected. In particular, it is contemplated to arrange the coating ( 70 ) in the area of the central part ( 65 ).

In order to ensure a uniform temperature control of the preforms ( 7 ) in the circumferential direction, the preforms ( 7 ) are at least temporarily set in rotation about their longitudinal axes during their heating.

Claims (16)

1. Device for the temperature control of preforms made of a thermoplastic material, which has at least one radiant heater, which is provided with electrical connections for energy supply and is supported by a support and in which a reflector is arranged opposite the radiant heater, characterized in that the reflector ( 22 ) has a plate-like central part ( 65 ) which extends essentially parallel to the radiant heater ( 62 ) and at least two plate-like side parts ( 66 , 67 ) which run at least in regions at an angle to the central part ( 65 ). 2. Device according to claim 1, characterized in that the side parts ( 66 , 67 ) are inclined relative to the central part ( 65 ) at an angle in the range from 20 ° to 40 °. 3. Device according to claim 2, characterized characterized in that the angle of inclination is about 30 ° is. 4. Device according to one of claims 1 to 3, characterized in that the central part ( 65 ) spans a flat plate. 5. Device according to one of claims 1 to 4, characterized in that at least one of the side parts ( 66 , 67 ) spans a flat plate. 6. Device according to one of claims 1 to 4, characterized in that at least one of the side parts ( 66 , 67 ) spans a curved plate. 7. Device according to one of claims 1 to 4, characterized in that at least one of the side parts ( 66 , 67 ) is formed from plate-like segments. 8. Device according to one of claims 1 to 7, characterized in that the reflector ( 22 ) at least in regions has a coating ( 70 ) for wavelength transformation. 9. The device according to claim 8, characterized in that the coating ( 70 ) has a substance for extending the wavelength. 10. The device according to claim 8, characterized in that the coating ( 70 ) has a substance for shortening the wavelength. 11. The device according to claim 8, characterized in that the coating ( 70 ) has both a substance for shortening the wavelength and a substance for extending the wavelength. 12. Device according to one of claims 8 to 11, characterized in that the coating ( 70 ) has a substance which changes the wavelength of the radiation only in a selective frequency range. 13. Device according to one of claims 1 to 12, characterized in that the reflector ( 22 ) is arranged in the region of a heating section of a single-stage device for container formation. 14. Device according to one of claims 1 to 12, characterized in that the reflector ( 22 ) is arranged in the region of a heating section of a two-stage device for container formation. 15. The device according to one of claims 1 to 14, characterized in that the central part ( 65 ) has a width which corresponds approximately to an outer diameter of the preform to be tempered ( 7 ). 16. Device according to one of claims 1 to 15, characterized in that the coating ( 70 ) is arranged in the region of the central part ( 65 ).