EP2125327A1

EP2125327A1 - Aftercooling device and method for aftercooling preforms

Info

Publication number: EP2125327A1
Application number: EP08708179A
Authority: EP
Inventors: Stefan Bock
Original assignee: Netstal Maschinen AG; Maschinenfabrik und Giesserei Netstal AG
Current assignee: Netstal Maschinen AG
Priority date: 2007-01-25
Filing date: 2008-01-25
Publication date: 2009-12-02
Also published as: CA2676615A1; CN101588910A; MX2009006790A; BRPI0807856A2; JP2010516507A; WO2008090207A1; CA2676615C; CN101588910B

Abstract

The invention relates to a device and a method for finishing and calibrating preforms (10) which are removed from a multiple injection tool in an unstable shape, and proposes an air cooler integrated into the water cooled cooling jackets (21) for the outer side of the open end face of the preform (10). Particularly in the case of special preform varieties, the areas which are unsupported in the cooling jackets (21) can be prestrengthened on the outside, from the beginning of the transfer from the open molds (8, 9) to the removing and/or cooling jackets, by means of a cooling which uses cooling air or deep cooled air. With the novel solution, the highest quality can be assured, in particular with respect to dimensional stability and the absence of pressure points under load, by means of a calibration in the cooling jackets (32) and the treatment in the area of the aftercooling.

Description

Aftercooler and method for post-cooling preforms

Technical area

The invention relates to an aftercooling device for preforms, wherein the still dimensionally unstable preforms are removed by means of a removal gripper, the open mold halves of an injection molding and at least partially nachkühlbar in water-cooled extraction or cooling sleeves.

The invention further relates to a method for the aftercooling of preforms with a threaded part, a blowing part and a neck ring, which are at least partially cooled in still hot, form unstable state in water-cooled cooling sleeves.

State of the art

In practice, three aftercooling systems have become established for the production of preforms:

According to a first concept, the still hot preforms are transferred directly to the cooling sleeves of an aftercooler. In this case, the aftercooler has a multiple of cooling positions in relation to the number of preforms of a Spritzgiesszyklus.

According to a second concept, the preforms are removed from the open molds by a light removal robot without cooling effect and transferred to an aftercooler and subsequently cooled. According to a third concept of the applicant, the robot function is divided into a removal gripper with water-cooled removal sleeves and an additional transfer gripper for transfer to an aftercooler.

According to the latest development, the injection molding machine cycle time is further shortened, whereby the preforms are removed from the molds in a soft and dimensionally unstable state. But so far less noticed problems come to the fore. For physical reasons, the cooling within the walls of the preforms runs unevenly:

As soon as the preforms are removed from the open mold halves, they pass through the

Temperature differences within the preform, in particular the Preformwandung, immediately thermal stresses or shrinkage stresses in the preforms and thereby

Shape changes on.

Every mechanical intervention and every handling by robotic grippers can be too

Mold damage.

The same occurs at horizontal position of the preforms in the aftercooler.

Thus, any intervention in the context of post-cooling to a very delicate work. In the production of injection molded parts by means of injection molding machines, the cooling time is a determining factor for the duration of a full cycle. The first and main cooling performance still takes place in the injection molds. Both injection mold halves are intensively water cooled during the injection molding process, so that the temperature of the injection molded parts can still be reduced in the form of, for example, 280 ° C at least in the outer layers to a range of about 70 ° C. It is in the outer layers very quickly below the so-called glass transition temperature of about 80 ° C. The actual Injection molding process until the removal of the injection molded parts could be almost halved in the recent past. This with optimal qualities in relation to the preforms. The preforms must be solidified in the mold halves so strong that they can be taken without damage from the removal aids and handed over to a removal device. The removal device has a shape adapted to the dimensions of the injection molded part. The intensive water cooling in the injection mold halves results, for physical reasons, a time-delayed temperature reduction down to the core area of the preform wall. This means that the mentioned about 70 ° C are not uniformly achieved in the entire cross section. The consequence is that seen in the material cross-section, a rapid re-heating from the inside to the outside, as soon as the intensive water cooling is interrupted by the forms. Aftercooling of the preforms outside the mold is of great importance for two reasons. Changes in shape but also surface damage, such as bruises, etc., must be avoided during aftercooling. It must also be prevented that the cooling in the higher temperature range is too slow and set by re-heating locally harmful crystal formations. The goal is a uniform amorphous state in the material of the finished preform. The residual temperature of the finished preforms should be so deep that in large packing containers with thousands of loose poured molded parts at the points of contact no pressure and adhesion damage can occur. The finished molded parts must not exceed a surface temperature of 40 ° C even after slight re-heating. Aftercooling after removal of the hot, dimensionally unstable preforms from the injection mold is very important for dimensional accuracy.

With WO 2004/041510, the Applicant proposes an intensive cooling station and a post-cooling station and, in the case of the intensive cooling station, insertable cooling pins for internal cooling in the preforms. The inner shape of the cooling sleeves is matched to the corresponding inner shape of the injection mold, such that the preforms after removal from the injection molds are as far as possible inserted into the cooling sleeves as far as possible to the solid wall system. If the preforms are in a lying position during the first phase of the aftercooling, then they tend to lay down on the corresponding cooling sleeve part. Due to a more intensive cooling contact in the lower area, the preforms are cooled down more strongly, whereby stresses occur in the preform and the preform has a tendency to ovalize. If in the first phase of the aftercooling with shortened cooling in the injection molds individual preforms slightly deform, then the corresponding shape change in already solidified preforms can not be corrected. By a targeted control of suction and blowing air, a swelling pressure can be generated in the interior of the preforms according to a preferred embodiment of WO 2004/041510 and the not yet solidified preform be brought to complete concern to the entire inner wall surface of the cooling sleeve. After the full application of the preforms to the inner wall surface of the cooling sleeves, the surface contact is maintained for several seconds and produces a calibration effect for each individual preform. The calibration effect gives a high production and quality standard in the production of preforms, as it was not possible in the older state of the art. The preforms are brought back into an exact form in this way shortly after removal from the injection molds. Any dimensional changes are reversed after the first critical handling of the injection molds in the cooling sleeves again. The calibration of the preforms allows them to be taken out of molds at even higher temperatures and to achieve an even shorter injection cycle time.

WO 2004/041510 proposes two variants for the generation of an inflation pressure. According to a first variant, a sealing ring is arranged on a cooling pin or on a blowing nozzle which is brought to bear against the conical transition in the preform interior. According to the second variant of the solution, the blowing nozzle has annular seals which are intended for the frontal support of the opening edge of the preform. Here, the swelling pressure acts on the entire preform. The disadvantage of both solutions is that in practice in multiple injection molding with, for example, 100 to 200 mold cavities a very high precision for the guidance or movement of all nozzles must be assumed.

EP 900 135 proposes a concept analogous to the aforementioned second solution variant. The sealing of the Oeffnungsrandes requires a certain compressive force and also a sufficient dimensional stability of the threaded portion. In order to avoid changes in the shape of the threaded part, the preforms must be left to a higher dimensional stability in the injection molds. But this is contrary to a shortening of the injection molding cycle time.

On the basis of more extensive investigations, it was recognized that a calibration of the still hot, dimensionally unstable preforms immediately after the removal of the removal robot from the open mold halves brings great advantages. However, the success did not come at all Preform types. It was found that with preforms with a non-threaded thread area with respect to the cooling sleeves, the problems of dimensional accuracy could not be solved. It has been recognized by the inventor that with an ever shorter machine cycle time, the entire open end side can be particularly endangered for handling in the area of aftercooling. This not least because the threaded part protrudes from the cooling sleeve and can not be cooled over the cooling sleeve. This is true regardless of whether the peform is calibrated or not.

The invention has now the object of developing a method and a device which, in the field of aftercooling, especially with respect to handling, at least in common preforms, ensuring the highest quality parameters and a maximum dimensional accuracy of the preform with the shortest possible cycle time allowed.

Presentation of the invention

The aftercooling device according to the invention is characterized in that the cooling sleeves are integrated in the region of the outer open end side of the preforms with air blowing devices, via which the outer skin, at least one unsupported region of the preforms, can be solidified with cooling air.

The inventive method is characterized in that the outer skin, at least part of the outer open non-supporting end sides of the preforms, are cooled by air blowing devices, which are integrated in the cooling sleeves with cooling air and thereby solidified.

It has been recognized by the inventor that a calibration after introducing the hot preforms into the cooling sleeves with a substantially cylindrical or slightly conical blowing part brings a great progress for the production of classical preforms. For calibration, the interior of the preform, at least of the blow-molded part, must be mechanically sealed. Already the force of the compressed air for the calibration, but at least as the mechansiche sealing force creates new problems when the area of the open end of the Preformwandabschnitte is not supported by the cooling sleeve inner wall. The equally important finding is that the outer side of the open end of the preform can be solidified immediately after the transfer from the open mold halves to the cooling sleeves, as soon as the air cooling is integrated in the cooling sleeves. This means a gain in time of, for example, 1 to 2 seconds in order to bring the targeted thread area by a further external cooling by means of cooling air in a more dimensionally stable state. In the case of the blower part, a corresponding external cooling could immediately bring disadvantages in that the calibration would require larger air pressures. In the cylindrical portion of the blower immediately acts the water cooling of the cooling sleeves by direct wall contact. This showed from the beginning a great success. The entire area of the neck ring should be air-cooled or solidified so far from the outside that the mechanical forces due to sealing forces can no longer cause any form of damage. In the case of calibration, the location of the external air cooling is preferably chosen to be approximately from the inside vis-a-vis the sealing force of the press or sealing rings.

The new aftercooling solution prefers the concept of a thermo-bottle closure for calibration and / or handling. The delicate wall material is equal to both applications. In one case it is glass, in the other it is the still easily deformable plastic. The sealing point does not have to be determined with the highest precision according to the solution according to the invention. The great advantage of the new invention is that, with full achievement of all quality criteria, a massive reduction of the entire cycle time and a corresponding increase in performance of the injection molding machine of 15% to 20% is made possible. The demolding of the preforms can take place earlier, in a still highly dimensionally unstable state of the preforms.

In practice, there is a large variety of preforms that can make a specific treatment necessary.

Particularly tricky prove to be preforms, which have a conically tapered neck lug between the cylindrical blower and the neck ring.

Another delicate preform has an extension in the corresponding neck part. The new invention makes it possible that even with a strong reduction of the dry-running time, the dimensional accuracy can be fully maintained. This means that due to the special air cooling of the outer open end side there is also a reserve for an even shorter machine cycle time. Field tests have shown that with clear preforms the machine cycle time can be reduced by 15% and with dyed preforms by 20%.

The new invention allows a number of particularly advantageous embodiments. It is to the claims 2 - 17 and 19 - 29 reference.

Advantageously, in the case of a calibration, the compressed air swells steplessly from the beginning of the calibration. As a result, the shrinkage compensation can be continuously achieved even with increasing solidification of the preform. Preferably, the compressed air supply is ensured by programmed increase of the control voltage of a control valve and a corresponding increase in the calibration pressure reproducible.

Very particularly preferably, the aftercooling device is assigned a refrigeration unit for generating cryogenic air, in particular below 0 ° C. It is associated with a pressure generator for the cooling air, with an air pressure of less than 2 bar, preferably less than 1, 2 bar, for the cooling air can be generated. Advantageously, the operation of the insert is controlled, the aftercooling device having a control by means of which the air blowing device can be activated immediately, from the moment of the preform transfer to the removal or cooling sleeves. The use of deep-frozen air brings two enormous advantages: First, an even more intensive immediate solidification of the outer skin in the opening area can be achieved immediately after the transfer of the preforms, which are still hot-drawn from the injection molds. This means that before any mechanical action by handling or calibration occurs, this particularly endangered lot is so strongly solidified that no more ovalization or local flatulence occurs. The frozen air allows as another advantage to reduce the amount of cooling air. For example, the air pressure can be reduced to only 1 bar instead of 4 bar. It can be achieved with a much smaller amount of air, the same effect as with ambient air. In particular, the frozen air can be controlled in terms of quantity and temperature targeted. According to a particularly advantageous embodiment of the new invention, it is proposed that the air blowing device is designed as directed against the outer, open end side of the preforms air ducts. Preferably, the aftercooling device has an activation and deactivation control, by means of which the air blowing device can be activated from the moment of preform transfer to the removal or cooling sleeves and during the calibration phase. The solution according to the invention can be used in the field of aftercooling wherever there is a risk of damage due to handling.

A particularly advantageous embodiment has a gripper with a plurality of nipples, each with an insertion in the preforms and the insertion of the nipples radially aufbauchbare pressing or sealing rings, which are insertable into the preforms. The pressing rings are preferably formed as radially aufbauchbare sealing rings, via which a sealing force in the direction of the inner wall of the preforms can be generated via a bore in the nipples in the interior of the blower part of the preforms for the construction of an inflation pressure. Particularly preferably, the inflation pressure is controlled such that a minimum pressure can be started and this swells up to the optimum pressure.

Another important design idea is that the nipples can be introduced position-controlled to a selectable optimum sealing point in a range between threaded part and blower in the preforms. This can accommodate a wide variety of forms of transition between threaded part and blower. The best sealing point is sought at the beginning of each production. After retracting the nipples, the outer wall of the entire preform blow-molded part must be in wall contact with the corresponding inner wall of the extraction sleeve. Preferably, therefore, the preforms are already introduced into the removal sleeves when they are taken over by the removal sleeves until complete and full inner wall contact of the entire blow molding part, including the closed bottom part. The preforms are post-cooled during the period of several injection molding cycles in water-cooled cooling tubes of an aftercooler, wherein the calibration takes place within the duration of an injection molding cycle or is limited by the duration of an injection molding cycle. The removal of the preforms from the cooling sleeves can be done easily.

According to the device, each nipple on two relatively movable pipe sections, at the end of each a retaining shoulder is firmly attached. For both previously described Solutions has each nipple air channels, via which controlled compressed air in the interior of the Blasteile the preforms can be fed. By means of controlled adjustment means, the actuator plate is moved with respect to the platform, for a simultaneous activation of the press or sealing rings. The adjustment means have a pure support function during the calibration. The press or sealing rings keep in squeezed state on the preform inside. Even a small force of the adjusting means for the actuator plate is sufficient for a good sealing. Advantageously, the nipples are arranged on a common actuation plate on a platform, via which the retraction and extension movement of the nipple into or out of the preforms and the positioning of the nipple takes place within the sampling sleeves. For this purpose, the platform controlled drive means are assigned to the positioning of the press or sealing rings in an optimal penetration or at an optimal location.

According to a first preferred embodiment, the removal of the preforms from the removal sleeves and the transfer to cooling sleeves of an aftercooler takes place when a sufficient dimensional stability is achieved, but within the time of an injection molding cycle. After calibration, the press or sealing rings can be relaxed and the pressure in the interior of the blowing parts can be released. A negative pressure can be generated via the air channels via the nipples and the preforms can be transferred to the aftercooler by means of the nipples. The nipple has no cooling function for this purpose. Preferably, during the short calibration time no exchange of air between the interior of the preform and the ambient air. The nipples are equipped with air channels, via which in the preforms vacuum for Preformentnahme can be generated. Within the nipples, the air duct for compressed air and suction air can be the same. Preferably, the pipe sections are arranged displaceable one inside the other, wherein the inner pipe section has at least one air channel. For the concept of the first approach, the device has a controllable removal gripper, with a number of removal sleeves, which corresponds at least to the number of injection positions of the injection molds. The device is equipped with a controllable compressed air connection for generating an inflation pressure in the interior of the preforms for the calibration of the preforms and a controllable connection for suction, wherein after switching to vacuum instead of the inflation pressure, the preforms can be removed by means of the nipple from the removal sleeves. In this concept, the device next to the removal gripper consists of an aftercooler and a transfer gripper for the transfer or for relocating the preforms from the removal gripper to the aftercooler, for final cooling of the preforms, regardless of the injection molding cycle. According to a second advantageous embodiment, the device has an aftercooler designed as a removal robot with a multiple number of cooling positions with respect to the injection positions of the injection molds. Here, the preforms to be transferred hot are inserted into each free cooling positions, calibrated, cooled intensively and ejected after the final cooling. Here, the nipples can support the ejection of the ready-cooled preforms from the extraction sleeves and the transfer to a conveyor belt with controlled suction and compressed air. Also, according to the second embodiment, after the calibration, the pressing or sealing rings can be relaxed, the pressure in the interior of the blowing parts drained, the nipple extended and held in a waiting position to repositioning the aftercooler for a new batch of preforms of the subsequent injection molding.

For both embodiments, the calibration of the preforms by compressed air and is limited in the period by the Spritzgiesszyklus. Pressing and calibrating the still soft preforms has enormous advantages:

First, by the firm pressing of the outer skin of the preforms to the inner, cooled with water withdrawal tube ensures maximum heat transfer and maximum cooling effect.

Secondly, the external dimensions of the preforms are accurately restored with the calibration and remain during the subsequent strain hardening.

Third, with the rapid passage of the so-called glass transition temperature, the physical quality parameters are ensured.

Fourth, with the production of a highly cooled and solidified outer material layer sufficient dimensional stability of the preforms for the subsequent handling of the removal sleeves in the cooling sleeves of an aftercooler and the subsequent discharge to a conveyor belt is achieved.

According to another particularly advantageous Ausgestaltungsweg device is proposed according to that the water-cooled removal sleeves in the area between the threaded part and the blower part ventilation ducts for a corresponding external cooling of the corresponding preform region, further having an air connection for the ventilation ducts. Depending on the geometric configuration of the preforms, the ventilation channels are in the transition region between the threaded part and the neck ring and / or arranged in the transition region between neck ring and blower. Preferably, the water-cooled extraction sleeves are formed from standardized parts, such that occasionally guide rings for the ventilation channels for cooling the transition region between the threaded portion and the neck ring and / or the transition region between neck ring and blower can be customized.

According to the method it is further proposed that an external cooling of the preforms by means of air is used immediately after the transfer of the preforms to the cooling sleeves of the removal gripper until the end of the calibration in the area between the threaded part and the blowing part. Preference for the calibration of nipples mounted press or sealing rings are position-controlled introduced into the transition region between the threaded portion and the neck ring or into the transition region between the neck ring and the blow molding in the preforms. In combination, the preforms are cooled and solidified from the outside in the transition region between threaded part and neck ring and / or into the transition region between the neck ring and the blow part from the outside already after being inserted into the cooling sleeves and during the calibration. A very special advantage is that even before the calibration on the critical non-supporting parts of the preforms, immediately after the transfer from the open mold halves to the cooling sleeves, the outer skin of the preforms is immediately solidified more strongly, so that the mechanical gripper forces no negative impact on the have corresponding areas. In the case of preforms with a widening neck, the transition region between the threaded part and the neck ring is air-cooled from the outside. Here, the preforms are pushed to the stop of the neck rings on the front side of the cooling sleeves, wherein the cooling sleeves are formed so that between the bottom part of the preforms and the corresponding bottom part of the cooling sleeves a minimum gap, preferably in the range of hundredths of a millimeter, remains can be canceled with the calibration. Brief description of the invention

The invention will now be explained with reference to some embodiments with further details. Show it:

1 shows schematically the new invention in a ready position before

Calibration of the preforms; FIG. 2a shows a nipple optimally inserted into a preform in the region of the open end side of the preform; Figure 2b shows a nipple in an enlarged scale with a floating arranged pressing or sealing ring. FIG. 3 a shows an external cooling of the transition region between

Threaded part and blown part of the preforms; Figure 3b shows a partial section of Figure 3a on a larger scale; FIG. 4a shows a detail enlargement of an air-outside cooling; FIG. 4b shows an air-outside cooling in a preform with a widening neck part; Figures 5a, 5b and 5c again very schematically show an optimal

Penetration of the press or sealing rings and the external cooling, wherein in the figures 5b and 5c additionally a Luftaussenkühlung the delicate, non-supported areas takes place; FIG. 6a shows a differently configured thick-walled preform with corresponding positioning of the nipple or of the sealing ring; FIG. 6b shows the solution according to FIG. 6a, but the inflation pressure has been released and the sealing ring has been relieved; FIG. 6c shows the removal of a preform by means of the nipple in the function of a holding nipple; Figure 7 schematically shows an example of a first approach with an additional aftercooler; 8 shows schematically an example of a second approach in which the

Removal robot is designed as an aftercooler; FIG. 9 shows a heat profile recorded on a preform, which without

Calibration was created; FIG. 10a shows a test example with a preform calibration; FIG. 10b shows a faulty preform in which the transition region which was not supported in the cooling sleeve without solidification according to the invention.

Ways and embodiments of the invention

FIG. 1 shows a situation after extension of the removal device 11 from the open mold halves 8 and 9 and the beginning of the calibration and the intensive cooling. The platform 17 with the nipples 30 is already in a ready position for a retraction movement into the preforms 10 according to arrow 31. The platform 17 is supported via an arm 14 on a displacement device 32 and linear guide rails 33 on a support bracket 36 and is connected via a linear drive 34th moved parallel to Maschinenaxe 37. The linear drive 34 is anchored to the back of a tab of the support plate 4. With the activation of the linear drive 34, the nipple 30 on the removal device 1 1 and moved away (as indicated by arrow 31). The actuator plate 16 are associated with adjusting means 18, which is the only function the squeezing and relieving the Pressbzw. Have sealing rings 56.

Figures 1 and 7 show schematically an injection molding machine for preforms with the following main elements: a machine bed 1, on which a support plate 4 and a fixed mold mounting plate 2 and an injection unit 3 are mounted. A movable platen 5 is supported axially displaceably on the machine bed 1. The two plates 2 and 4 are interconnected by spars 6, which are passed through the movable platen 5. Between the support plate 4 and the movable platen 5 is a drive unit 7 for generating the closing pressure. The fixed platen 2 and the movable platen 5 each carry a mold half 8 or 9, between which a plurality of cavities can be formed to produce a corresponding number of sleeve-shaped injection molded parts. The injection molded parts 10 are produced in the cavities between mandrels 26 and cavities 27. After opening the mold halves 8 and 9, the sleeve-shaped injection-molded parts 10 adhere to the mandrels 26. The same injection-molded parts 10 in the finished cooled state are shown in Figure 7 top left, where they are just dropped from a Nachkühleinrichtung 19. The upper spars 6 are for the purpose of better showing the details between the open mold halves shown interrupted. According to the solution according to FIGS. 1 and 7, the four method steps for the injection-molded parts 10 after completion of the injection molding process correspond to a first approach:

"A" is the removal of the injection molded parts or preforms 10 from the two mold halves.

The still plastic parts are thereby from one in the space between the open

Mold halves lowered sampling device 1 1 recorded (Figure 1) and raised with this in the position "B".

"B" is the phase of calibration and intensive cooling.

"B" / "C" is the transfer of the preforms 10 from the removal device 1 1 to a

Transfer gripper 12 and the transfer of the preforms 10 of the transfer gripper 12 to a

Aftercooler 19, according to the first solution.

"D" is the discharge of the cooled and brought into a dimensionally stable state preforms

10 from the Nachkühleinrichtung 19.

Figures 1 and 7 show as it were snapshots of the main steps for the handling according to the first approach. In the position "B", the injection molding parts 10 arranged vertically one above the other are taken over by the transfer gripper 12 or 12 'and brought into a standing position, according to the phase "C", by pivoting the transfer device in the direction of the arrow P. The transfer gripper 12 consists of a pivotable about an axis 13 platform 17 which carries an actuating plate 16, which are arranged at a parallel distance from each other. The actuator plate 16 is parallel to the platform 17 via a drive or adjusting means 18 exhibited, so that in the position "B" the sleeve-shaped injection molded parts 10 taken from the removal device 1 1 and pivoted in the position "C" position in the overlying Nachkühleinrichtung 19 can be pushed. The respective transfer takes place by changing the distance "S" between the actuating plate 16 and the platform 17. The still hot injection-molded parts 10 are ready-cooled in the Nachkühleinrichtung 19 and ejected after a displacement of the Nachkühleinrichtung 19 in the position "D" and on a conveyor belt 20th thrown. The reference numeral 23 denotes the water cooling with corresponding supply and discharge lines, which are indicated for simplicity with arrows and are assumed to be known. The reference numerals 24/25 indicate the air side, wherein 24 for the injection resp. the compressed air supply and 25 for the vacuum resp. Air suction stands (Figures 6a and 6c). From Figure 2a, the direct relationship between the function of the nipple 30 as Kalibriernippel and the conical portion 47 of a preform 10 is expressed. The corresponding conical outer part of the preform 10 is cooled in advance immediately after removal from the open mold halves 8, 9 in advance and solidifies the non-supporting outer wall layer within the cooling sleeve 21 (FIG. 3b). This gives the entire preform at the tapered transition 47 a sufficient dimensional stability. Outwardly, the air guide ring 1 14 is held within the head portion 143 of the cooling sleeve 21. During assembly, the air guide ring 114 is inserted with the inner sleeves 144 of the cooling sleeve 21 from right to left. The cooling air is indicated by the arrows 145, 145 '. FIGS. 2a and 3b show that before the pressing or sealing ring 56 comes into contact with the preform, the cooling air is in action.

FIG. 2b shows the insertion part of the nipple 30 according to FIG. 6a on a larger scale. A very preferred feature is the floating bearing of the pressing or sealing ring 56. The pressing ring 56 is held on both end sides by means of loose support rings 100. The two loose support rings 100 have an inner diameter "D", which is greater by a small clearance than the outer diameter "d" of the support tube 52. Also in the longitudinal direction is game "Sp" between the support ring 100 and the connector 80. So gets the pressing or sealing ring 56 in the inactive state a freedom of movement in terms of a slight Taumeins or swimming. The result is automatically an optimum annular sealing point, e.g. 57, 57 'or 57 "on the pressing or sealing ring 56.

FIGS. 3a and 3b show an external cooling of the preforms 10xx in the not uncritical transition 47 between the threaded part 44 and the blower part 43. Many preforms 10xx have an outer conical taper 110 in this section. This conical taper 10 is disadvantageous inasmuch as the region 47 of the taper vis-a-vis the cooling sleeve 21 is unsupported. There is no contact with the inner wall 1 11 of the cooling sleeves. Cooling air can be injected via an air connection 1 12 and discharged back into the open air via a cooling duct 1 13. This additional cooling has the great advantage that it can be used effectively from the first moment of transfer of the preforms 10 to the cooling sleeves 21 and additionally over the entire calibration time. With an additional solidification of the relevant Preformaussenseite a possible deformation by the contact pressure of the pressing or sealing ring 56 is counteracted. The most striking structural difference to a "normal" cooling sleeve lies in that an air guide ring 14 is arranged in the open mouth region. On the inside of the air guide ring 114, an annular cooling channel is arranged from the point of the air connection 1 12 to the Abblasstelle 1 13 'to the environment around the respective preform part. Thus, the cooling air sweeps targeted the whole corresponding consiche outside of the preforms to the front side of the neck ring 137th

FIGS. 4a and 4b show a preform 10x with a conically widened neck piece 136. In this preform type, the widened neck piece already belongs to the blow molding part and rests on the inner wall of the cooling sleeve 130 during the calibration. The cooling sleeve inner wall gives the preform 10x the definitive outer shape. The whole blown part of the preform 10x is up to the neck ring 137. The optimum sealing point of the pressing or sealing ring 56 lies in the region of the cylindrical portion in the region of the neck ring 137 (FIG. 5b). But this part is at risk of deformation of the pressing or sealing ring 56 in terms of deformation, since this part is only partially supported from the outside. Here comes the additional external air cooling (KL) to bear. With the air cooling of the threaded part 44 and the neck ring 137, the outer skin of the thread 44 gets a higher strength. This is independent of whether the preform is calibrated or not.

FIG. 4b shows yet another interesting design concept. The cooling sleeve is composed of standardized components and consists of an inner cooling sleeve 130, an outer cooling sleeve 131 and a jacket sleeve 132 and a head ring 133, with which the air channels (gap Sp) are formed. Depending on the shape of the preform 10, 10x, 10xx, the inner cooling sleeve 130 is designed and a corresponding head ring 133 or 1 14 mounted. With 138 the lowest thread, with 134 of the base of an actuator plate and 135 denoted the sealing rings. According to FIGS. 4a and 4b, the cooling sleeve 10x is designed so that a minimal gap 139 of a few tenths of a millimeter remains after the insertion of the preforms into the cooling sleeves at the bottom part. In contrast, the neck ring 137 should already rest completely upon insertion of the cooling sleeve.

It can be dispensed with in many cases in a purely cylindrical blower, according to Figure 5a, an external cooling. However, in the endeavor to shorten the machine cycle time even more, it may also be advantageous in the case of preforms with a cylindrical blow-molded part to solidify the threaded part early, so that any handling during the after-cooling does not lead to any damage to the thread. FIG. 5b shows a preform with an enlarged diameter in the region of the open end. This preform is no longer supported in the area Neckring 137 and thread in the cooling sleeve. Here it is therefore of great advantage if the outer skin of said area is solidified immediately after the transfer of the injection molds to a removal gripper with cooling air.

FIG. 5c shows a solution which can prevent deformations, especially bumps in the relevant section, when the corresponding blow part is tapered (FIG. 10b). This is especially true for extremely short cycle times of less than 10 seconds and for thicker preform wall thicknesses. In the common preforms for PET bottles of 1 - 2 liters content of treated with cooling air section is usually 3 to 5 cm, the thread itself makes up about 2 cm.

It is clear from the above that for the preforms 10, 10x, 10xx from the moment of removal from the open mold halves

the best possible cooling conditions exist at all times; The preform will, except for a brief interruption, immediately after

Sliding from the open mold halves in the cooling sleeves until retraction of the

Nipple 30 during the calibration phase to the inner cooling surfaces of the

Extraction sleeves 40 pressed on; the short break for a 100% concern of the preform 10 is made up for by the much longer lasting calibration; After calibration, the preforms 10, 10x, 10xx are already in a dimensionally stable state on all sides. Therefore, the preforms 10, 10x, 10xx remain dimensionally stable in their outer geometric shape after calibration until the final cooled state.

With maximum design of the water cooling circuits

==> in the injection molds,

==> in the field of injection molding cavities and injection molding mandrel as well

==> in the extraction sleeve a maximum intensive effect is generated. It is not the goal within a Spritzgiesszyklus the preforms 10, 10X, 10xx ready to cool. However, it is desirable to bring the preforms 10, 10x, 10xx to the end of the two to three times longer post-cooling in a pourable, storage and transportable state.

This results in big advantages:

==> the prerequisite for an extreme shortening of the cycle time,

==> thus further increasing the productivity of

injection molding machine,

==> a maximum dimensional accuracy of the preforms

==> as well as the best possible qualitative properties of the preforms, for example with regard to crystallinity, dimensional accuracy and freedom from damage.

FIGS. 6a, 6b and 6c show the calibration and removal of the preforms 10 from the extraction sleeves 40 by means of the nipples 30 in the function of holding nipples. Above the nipple 30, the interior of the blower part is set to negative pressure (FIG. 6a), or the preform 10 is sucked to the nipple 30 (symbol) according to FIG. 6b. On the support tube 52, a centering ring 58 is attached at the rear end, which fits exactly to the open end of the preform 10, for holding the preforms exactly on the nipples 30. On the opposite side of the preform 10, compressed air is applied to the closed preform end (+ sign ) according to FIG. 6c. The preform 10 goes to stop 50 to the actuator plate 16 and the removal sleeve 40 can be completely removed and passed, for example, the aftercooler or be dropped according to a second approach by switching to compressed air.

In the figure 6a, the control of the compressed air supply is shown schematically. Via a voltage-controlled control valve 35, 38 is set via the voltage in volts by means of control 39, the compressed air supply for the calibration, preferably from the beginning of the calibration, a continuous swelling of the inflation pressure is sought. This can be counteracted by cooling effect of the cooling sleeve 21-adjusting shrinkage of the preform 10 and a rapid solidification of the outer skin can be achieved. The preform 10 can thus be pressed against the inner wall of the cooling sleeve in an optimal manner during the entire duration of the calibration without causing bloating in the area of the unsupported areas or damage due to the handling of the preforms. FIG. 7 shows a station at the end of the injection process with opened mold halves 8 and 9, respectively. The temperature of the preforms 10 was lowered in the mold with maximum cooling effect. The preforms 10 may well still be dimensionally unstable, such that they could deform with immediate ejection after the mold opening at the slightest external force. At the end of the injection process, the removal device is already in start position (Figure 1) and can be lowered after the mold opening without time delay between the open mold halves. In the solution shown in FIG. 7, an independent post-cooling device 19 is used, in which the still-hot preforms 10 are finished cooled during 3 to 4 injection molding cycles. In the "B" / "C" phase of FIG. 7, a transfer gripper 12 transfers the preforms 10 to the post-cooling device 19. The post-cooling of the preforms takes place in water-cooled sleeves.

In FIG. 7, the horizontal plane is designated by EH and the vertical plane by EV. The horizontal plane EH is defined by the two coordinates X and Y and the vertical plane by the coordinates Y and Z. The Z coordinate is vertical, and the X coordinate is oriented transversely to it. The transfer gripper 12 performs a pivotal movement as well as a linear movement in the X-coordinate. The transfer gripper 12 can be additionally formed with a controlled movement in the Y-coordinate. Because the transfer gripper 12 already has a controlled movement in the X coordinate, the exact positioning of the preforms 10 located on the nipples 30 of the transfer gripper 12 in the X direction can be performed by a correspondingly controlled / regulated movement. For the transfer of the preforms 10 to the aftercooler 19, the aftercooler 19 is moved in the X direction to a fixed position in this case, controlled the transfer gripper 12 in the Y direction / regulated and brought into the desired position. In the preferred embodiment, the movement means for the aftercooler 19 for the two coordinates X and Y for exact positioning for the transfer of the preforms 10 are controllable /. In this case, the transfer gripper 12 is set in each case in a fixed transfer position.

For this information, reference is made in full to WO 2004/041510, and also to PCT 2007/000319.

In the illustrated position of Figures 7 and 8, the two mold halves 8 and 9 in the open state, so that the aftercooler 60 can retract into the free space 62 between the mold halves. The aftercooler 60 has a total of three movement axes, a horizontal movement axis in the Y coordinate, a vertical movement axis in the Z axis. Coordinate and a Drehaxe 63, which are coordinated by a machine control 90. The Drehaxe 63 serves only the discharge of the finished cooled preforms 10 on a conveyor belt 20. The Drehaxe 63 is mounted relative to a base plate. Movement means for the vertical movement is a vertical drive 65. The vertical drive 65 is slidably mounted on a base plate 66 of a horizontal drive 67. The horizontal drive 67 has an AC servo motor with a vertical axis. The base plate 66 is mounted on four sliding on two parallel slides back and forth. The base plate 66 has on the right side of the image a vertically upwardly directed base plate part, on which the vertical drive 65 is anchored. The vertical drive 65 also has an AC servo motor with a horizontal axis.

The Nachkühleinrichtung according to Figure 8 has a plurality of parallel rows. In the example shown, 12 cooling sleeves 21 are shown in a vertical row. The cooling sleeves 21 can be arranged much closer in relation to the conditions in the injection molded parts. Therefore, not only will multiple parallel rows be proposed, but additionally an offset of the rows will be proposed. This means that for a first Spritzgiesszyklus the cooling tubes numbered 1, for a second injection cycle, the cooling tubes numbered 2, etc. are referred to. In the example with four parallel rows, if all rows are filled with # 3, the rows of # 1 are prepared for ejection onto the conveyor belt 20 as described. The remainder is analogous throughout the entire production period. In the example shown, the total after-cooling time is on the order of three to four times the injection molding time. The Luftdruckbzw. Vacuum conditions in the Nachkühleinrichtung 19 must be controllable in rows, so that at any given time all rows 1 and 2, etc. can be activated simultaneously. In addition to the accuracy of the path control of the aftercooler 19 and the platform 17, it is important that the acceleration and deceleration functions are optimally controlled. The visualization takes place in a command device of the machine control resp. of the machine computer 90 instead. The movements can be optimized in every way. This affects, for example, start and stop, but above all accelerations and decelerations in terms of speed and distance.

FIG. 9 shows a heat profile recorded on a preform 10xx, which was created without calibration. Note the large temperature difference of 62.8 ° C to 45.7 ° C. This results in a radial temperature difference at the end of the stem of the preform of 17.1 ° C. This led to an ovalization of the outer shape in the first cooling process. This undesirable ovalization can be reduced or prevented only by a longer cooling time in the mold tool. In the example shown, the heat profile shown was measured at a cycle time of 13.5 seconds. The quality was about 0.2 mm, which is just within the tolerance limit.

FIG. 10a shows a test example with the calibration of the preform 10xx with cooling air. The temperature distribution is in a much smaller range of only 3.9 ° C. The cycle time of 13.5 sec. Was lowered to 1 1, 5 sec. The ovality was only 0.05 mm instead of 0.2 mm. It follows that according to the invention more precise preforms can be produced with a shorter cycle time.

FIG. 10b shows a preform 10xx in which the external cooling according to the invention was not used. The calibration pressure was too high, causing it to bulge in the unsupported conical area.

Claims

claims

1. Nachkühlvorrichtung for preforms (10), wherein the still dimensionally unstable preforms (10) by means of a removal gripper (11) the open mold halves (8, 9) taken from an injection molding and at least partially nachkühlbar in water-cooled withdrawal or cooling sleeves (21), characterized in that the cooling sleeves (21) in the region of the outer open end side of the preforms (10) are integrated air blowing devices over which the outer skin, at least one unsupported portion of the preforms (10), is solidifiable with cooling air.

2. Aftercooling device according to claim 1, characterized in that it is associated with a refrigeration unit for generating cryogenic cooling air.

3. Aftercooling device according to claim 2, characterized in that it is associated with a pressure generator for the cooling air, with which an air pressure of less than 4 bar can be generated.

4. aftercooler according to one of claims 1 to 3, characterized in that it comprises a control by means of which the air blowing device from the moment of P reform transfer to the removal or cooling sleeves (21) can be activated.

5. aftercooler according to claim 4, characterized in that the cooling air quantity and / or the cooling air temperature is controllable, wherein the maximum values are adjustable immediately after the Preformübergabe.

6. Aftercooling device according to one of claims 1 to 5, characterized in that the air blowing device is designed as directed against the outer, open end side of the preforms air ducts or cooling channels (113).

7. aftercooler according to one of claims 1 to 6, characterized in that the water-cooled removal sleeves in the region between the threaded portion (44) and the blowing member (43) and the cylindrical shaft cooling channels (113) for a corresponding external cooling of the preforms (10 ), further comprising an air connection (112) for the cooling channels (113).

8. aftercooler according to one of claims 1 to 7, characterized in that in dependence on the geometric configuration of the preforms (10), the ventilation channels in the region between threaded portion (44) and neck ring (137) and / or in the transition region between the neck ring (137 ) and cylindrical blowing member (43) are arranged.

9. aftercooling device according to one of claims 1 to 8, characterized in that the water-cooled removal sleeves are formed such that the whole Preformblasteil, with the exception of the threaded portion (44) and the neck ring (137), is completely inserted into the removal sleeve.

10. aftercooler according to one of claims 1 to 9, characterized in that the water-cooled extraction sleeves are formed of standardized parts, such that occasionally guide rings (114) for the ventilation channels for cooling the transition region between threaded portion (44) and the neck ring (137 ) and / or the transition region between Neckring (137) and blower (43) can be used.

11. aftercooler according to one of claims 1 to 10, characterized in that it comprises means with a plurality of nipples (30) each having an insertion in the preforms (10) and the insertion of the nipple (30) radially aufbauchbare pressing or Have sealing rings (56) which are insertable into the preforms (10).

12. Aftercooling device according to claim 11, characterized in that the pressing rings are designed as radially aufbauchbare, in particular floating mounted sealing rings (56), via which for the construction of an inflation pressure in the interior of the blower member (43) of the preforms (10) a mechanically producible and adjustable sealing force in the direction of the inner wall of the preforms (10) can be generated.

13. Aftercooling device according to one of claims 11 or 12, characterized in that the nipples (30) with the particular floating bearing press or sealing rings (56) position-controlled in a selectable optimum sealing point in a region between the threaded part (44) and blower ( 43) in the preforms (10) are insertable.

14. Aftercooling device according to one of claims 11 to 13, characterized in that the preforms (10) in still hot, form unstable state of the injection mold for aftercooling water-cooled sampling sleeves transferable and by means of the in the preforms (10) insertable nipple (30) with compressed air can be calibrated to exact external dimensions.

15. aftercooler according to one of claims 11 to 14, characterized in that the nipple (30) on a common actuating plate (16) are arranged, which controlled drive means are assigned for the introduction and positioning of the pressing or sealing rings (56) in one optimum penetration depth or at an optimal location for the sealing rings (56) in the preforms (10) or in the removal cooling sleeves.

16. Aftercooling device according to one of claims 1 to 15, characterized in that it comprises a controllable removal gripper (11), with at least a number of water-cooled withdrawal sleeves, corresponding to the number of injection molding positions of the injection molds, preferably a 3- to 4-fold number of injection molding positions in the injection mold.

17. aftercooler according to one of claims 1 to 16, characterized in that it comprises a removal gripper (11) with the water-cooled removal sleeves, a transfer gripper (12, 12 ') with nipples (30) and an aftercooler (19) having a number of cooling positions which corresponds to 3 to 4 times the number of injection positions, wherein the blow part (43) of the preforms (10) in the sampling sleeves calibrated and the preforms (10) in a predetermined exact form within each injection cycle by means of the transfer gripper (12, 12 '), the aftercooler (19) and after the final cooling a removal (20) can be transferred.

18. A method for aftercooling of preforms (10) with a threaded part (44), a blower (43) and a neck ring (137), which are at least partially recooled in still hot, form unstable state in water-cooled cooling sleeves (21), characterized in that the outer skin, at least part of the outer open, unsupported end faces of the preforms (10), is cooled and thereby solidified with cooling air via air blowers integrated in the cooling sleeves (21).

19. The method according to claim 18, characterized in that the compressed air for the calibration from the beginning of the calibration swells continuously, so that the outer skin of the preform (10) continues to cool until the maximum inflation pressure for shrinkage compensation is achieved, wherein the swelling of the air pressure preferably By increasing the control voltage of a control valve in the compressed air supply is achieved.

20. The method according to claim 18 or 19, characterized in that is used as cooling air frozen air at a temperature in the range of preferably below 0 °.

21. The method according to claim 20, characterized in that cooling air of less than 4 bar is used.

22. The method according to any one of claims 18 to 21, characterized in that the cooling air insert is controlled, such that the maximum cooling effect takes place immediately after Preformübergabe.

23. Method according to claim 18, wherein an external cooling of the preforms (10 is done by air.

24. The method according to any one of claims 18 to 23, characterized in that in the case of preforms (10) with an expanding neck of the transition region between the threaded part (44) and neck ring (137) is air-cooled from the outside.

25. The method according to any one of claims 18 to 23, characterized in that in the case of preforms (10) with an outwardly tapered neck portion of this region of the preforms (10) is air-cooled from the outside.

26. The method according to any one of claims 18 to 25, characterized in that a) to nipples (30) mounted press or sealing rings (56) position-controlled in each of the preforms (10) in the region between the threaded part (44) and blower ( 43) are introduced, wherein b) the press or sealing rings (56) up to the contact to the inner wall of the preforms (10) and c) by generating a radially directed in the direction of the inner wall force of the interior of the blower member (43) is sealed outside.

27. The method according to any one of claims 18 to 26, characterized in that the blast parts (43) of the preforms (10) after insertion of the preforms (10) in the cooling sleeves (21) and the extension from the open mold halves (8, 9 ) within the period of a Spritzgiesszyklus the preforms (10) are calibrated to the inner wall of the cooling sleeves (12) by continuously swelling compressed air to exact external dimensions.

28. The method according to any one of claims 18 to 27, characterized in that the nipple (30) with the pressing or sealing rings (56) position-controlled in a selectable optimum sealing point in a region between the threaded part (44) and blower (43) in the preforms (10) are introduced.

29. The method according to any one of claims 18 to 28, characterized in that the preforms (10) immediately after insertion into the cooling sleeves (21) from the outside in the transition region between the threaded portion (44) and the neck ring (137) and / or be air-cooled to the transition region between the neck ring (137) and the blower (43) from the outside and in combination after extending the cooling sleeves (21) from the open mold halves (8, 9) by means of nipples (30) mounted press or Positionally controlled sealing rings (56) into the transition region between the threaded portion (44) and the neck ring (137) or into the transition region between the neck ring (137) and the blowing member (43) introduced into the preforms (10) and within an injection cycle be calibrated.