WO2009103805A1

WO2009103805A1 - Method and device for the compression injection moulding of preforms

Info

Publication number: WO2009103805A1
Application number: PCT/EP2009/052068
Authority: WO
Inventors: Stefan Bock
Original assignee: Netstal-Maschinen Ag
Priority date: 2008-02-21
Filing date: 2009-02-20
Publication date: 2009-08-27

Abstract

The invention relates to a method and a device for the compression injection moulding of preforms (10), comprising an injection moulding machine with a movable tool carrier plate (5) having a mould half (8) with cores (24) and a fixed tool carrier plate (2), to which a mould half with a plurality of mould nests or cavities (60) is assigned. The cores (24) adopt a filling or dosing position for producing an annular flow around said cores (24). The cores (24) penetrate the cavities (60) before completion of the melt dosage to such a depth that the mould nests are at least substantially closed to the exterior. The melt is introduced into the cavities (60) when the moulds are not completely sealed, the valves are closed and the compression pressure is produced using the cores (24) by the complete closure of the moulds.

Description

Method and device for compression injection molding of preforms

Technical area

The invention relates to a method for compression injection molding of preforms by means of an injection molding machine with a movable tool carrier plate having a mold half with cores and a stationary tool carrier plate, which is associated with a mold half with a plurality of mold cavities, wherein the melt on the side of the stationary tool carrier plate on metered valves are introduced into the mold cavity or cavities and the cores are so far penetrated into the cavities before completion of the melt dosage that the cavities are at least substantially closed to the outside.

The invention further relates to a device for compression injection molding of preforms by means of an injection molding machine, a movable and a stationary tool carrier plate with a mold cavity with a plurality of mold cavities, wherein the movable mold half is formed with a core carrier plate and with cores and the melt supply into the cavities arranged on the side of the stationary tool carrier plate and the injection nozzle to the mold cavities or cavities valve-closed is closed.

State of the art

In the production of flat plates, especially CD's, compression molding is a prerequisite. The melt is passed through the one half of the mold with relatively low pressure in the cavity, at a time, where the form is almost closed. However, the cavity is only partially filled with melt. As soon as the metered quantity of melt introduced is introduced, the movable mold half is moved toward the stationary mold half and, by reducing the size of the cavity, it is filled out and then the so-called embossing pressure is applied. As a rule, CD's are produced by means of a special injection molding machine with a horizontal movement axis.

The production of preforms is more problematic in that it is a hollow mold with a considerable length dimension. In industrial practice, preforms are produced in the classical spheroidal casting process by means of injection molding machines with a horizontal axis. For example, reference is made to WO 2004/073953 of the Applicant. The raw material is fed in granular form via a funnel to a plasticizing unit and prepared. In the injection cycle, a valve between the plasticizing screw and an injection piston is opened and metered into a melt deposit placed upstream of the injection piston. After closing the mold halves and opening the valve, the melt is injected in batches by way of hot runner nozzles into each of the cavities of the injection mold. The injection piston generates a sufficient hydraulic pressure over the required time. The preform is cooled rapidly. After, for example, 14 seconds, the mold halves are opened by withdrawing the core side of the tool or the corresponding movable mold half and the preforms are removed from the open mold halves. The corresponding technology has reached a high level today, so that up to 200 preforms with the highest quality can be produced in short cycle times.

The so-called compression injection molding has been known for at least for the production of thin-walled forms for over two decades. JP 620 90 210 proposes for a vertical press. A portion of processed melt is placed in the still open mold halves, and then the mold halves are closed with respect to the outer contours of the mold. As a next step, a plunger moves with the complementary bottom shape of the Container is formed, with a corresponding compression pressure and gives the molded parts the definitive shape.

EP 567 870 shows a hydraulic press for the production of plastic parts in the compression method. Again, the machine axis or the direction of movement of the movable mold half is vertical. In each case, a metered portion of melt is inserted into the open lower half of the mold and the exact part shape is produced by closing the molds. About appropriate control medium, the closing movement or the speed profile of the upper mold half can be controlled.

JP 202 21 0808 proposes to produce preforms with an analogous concept. In contrast to the aforementioned solutions, liquid melt is metered into the open cavity. Thereafter, the core, which generates the interior of the preform, retracted into the cavity and at the same time closed the mold. The amount of melt is chosen so large that with closed mold halves, the cavities are completely filled. It is not known to the applicant whether this solution could ever be put into practice.

JP 2001 000 219518 is another solution for the automated production of preforms. Here, the core is retracted before introducing the liquid melt in upright cavities. Thereafter, the melt is metered from below into the cavity via a valve-controlled spray nozzle, the core with the movable mold half is completely retracted, at the same time the mold is closed and the compression pressure is applied. The exact dosage can be adjusted by equalizing flows between the cavity and the valve needle vestibule.

The patents GB 2 430 642 and GB 2 430 643 show two further solutions for the compression injection molding of preforms. In this case, the injection mandrel moves horizontally in the direction of the solid mold half. The hot melt is on the side of the cavity via a controllable injection valve according to the injection cycle in the Cavity introduced. The solution is based on several plates, which are movable to the open side of the cavities. It is proposed a movable plate with the cores and a displaceable relative to the plate with the cores neckring plate. The plate with the cavities is formed with a sealing contact with a cylindrical outer portion of the cores. As a solution, it is proposed to provide means by which the relative velocity between cores and cavities in the phase in which the core approaches the cavity can be adjusted as a function of the distance between cores and cavities. It is assumed that it is not enough if only the pressure is regulated. During the injection phase, the cores can be pushed back by the injection pressure. The disadvantage of this solution is that the concept is only suitable for a small number of cavities. GB patent specification 2 430 642 proposes a shutter plate which can be moved independently of the cores. The closure plate allows the cores to move relative to the cavities.

Presentation of the invention

The object of the invention was therefore to search for solutions which allow 50 to 200 and more preforms to be produced by the compression spraying method in one cycle, without any qualitative losses with respect to comparably large injection molding machines of the prior art, for example according to WO 2004 / 073953, with the aim of shortening the machine cycle time for the production of preforms over the prior art.

The method according to the invention is characterized in that the cores occupy a filling or metering position around the cores to produce a ring flow, and the melt is introduced for each cavity in a predosed amount.

The inventive device is characterized in that by means of the cores, the open Preformseiten are lockable to the outside and the Device has a control device for positioning the core carrier plate or the cores in a metering position and pre-metered amounts of melt are introduced into the cavities, wherein the compression pressure for the production of the part shape in the individual cavities can be generated via the cores.

It has been recognized by the inventor that high productivity with the compression spraying method is only possible in the context of the currently best solutions of the prior art, for example according to WO 2004/073953. None of the previous compression spray techniques allowed to produce 200 preforms with cycle times of, for example, 8 to 15 seconds.

The new invention assumes

That the mold cavities are at least substantially closed to the outside before metering and the cores are moved into a filling or metering position,

Wherein in this position the melt is introduced as a ring flow of a pre-metered amount of melt into the cavity, preferably until it is completely filled

• And the compression pressure by means of the cores, preferably by the positive connection, is generated.

In the new invention, the actual injection process runs in three main phases:

• Phase 1: After closing the open end side of the preform

Retracting the cores in a controlled position, preferably on a first stop;

• Phase 2: close and dose the tool;

• Phase 3: Enable the advance of the cores to generate the

Compression pressure, preferably on a second stop. It is not mandatory that the cores occupy an exact position in the metering position. The cores can be moved via a control device within a filling area in such a way that the annular inflow of the melt into the cavity is optimized. For example, with the flow pressure of the melt, the core can be pushed back slightly until completion of the dosage. It is important that after completion of the dosage, the cavity is filled with the pre-dosed amount of melt and the cores occupy a predeterminable dosing position before the compression pressure starts. The compression pressure is built up and maintained for several seconds.

It is a known fact that a hot plastic mass at a pressure of about 1000 bar is such a strong elastic material that it is more than 10% compressible equal to a spring. Due to the fact that the metering pressure can be chosen much lower with, for example, 50 to 200 bar, the metering is correspondingly less affected by the compression behavior of the melt mass. This means that the dosage is better controllable and thus can be brought to a higher accuracy. Another advantage is that the sealing behavior of the cores and cavities with increasing compression pressure is better because on the one hand on the outer sealing surfaces applied a higher sealing pressure and on the other hand, the sealing length with the deeper penetration of the cores is greater.

The decisive advantage of the new invention is that, on the one hand with pre-dosed quantities a) the dosage for all preforms can be brought to a higher level with respect to the dosing accuracy with respect to an exact and equal dosage for each of the mold cavities, b) the dosing time can be massively shortened. This is because the dosage is prepared immediately before each mold cavity or each cavity and the predosing during the time Preformentnahme and the next dosing phase is prepared. A particularly important point is that a pre-metered identical amount of melt is simultaneously introduced into each of the mold cavities. This also has the great advantage that, for example, an exact final metering by a correction from a shrinkage compensation space is possible.

The new invention allows a number of particularly advantageous embodiments. It is for the claims 2 to 12 and 14 to 27 reference.

Preferably, the injection molding machine is designed as a horizontal machine, with horizontally movable mold half. In a horizontal position of the machine or the mold cavity meets after opening a valve needle, the first melt jet symmetrically directly to the top of the cores and is then deflected into a ring flow. Depending on the contour of the core tip, part of this melt may adhere to the tip, with the advantage that this particularly delicate batch cools down first. However, the injection molding machine can also be designed as a vertical machine.

Most preferably, the drive of the movable mold half via toggle lever, wherein the compression pressure is generated within 12 ° to 15 ° to the dead center of the toggle. The new solution takes advantage of toggle geometry in a double sense:

• The first movement of the cores takes place almost without resistance very quickly up to the dosing range, preferably with an adjustable first stop or stop at the beginning of the dosing phase.

• The second movement for the compression pressure can be delayed, but with the maximum possible closing force close to the extended position of the toggle lever on a second adjustable stop or stop.

According to a further embodiment, the drive of the movable mold half hydraulically or electrically, in particular via a linear drive or a servomotor, take place. Especially in the case of a drive with servomotor or Linear motor, the core movement with maximum accuracy controlled repeatable, regulated in the phase of cavity filling and selectively positioned without mechanical stop or programmed as a movement sequence.

The dosage is prepared for each one dosing for each shot and for each mold cavity in an upstream dosing antechamber. In this case, the pre-metering quantity in the metering antechamber is codetermined by a double valve associated with each mold cavity, which valve is designed as an injection valve on one end side and as a feed valve on the other end side of a valve needle. About a controlled movement, the injection valve is alternately opened in the mold cavity or in the entrance to the dosing antechamber in a shrinkage compensation chamber and the opposite each output closed. Furthermore, the individual metering antechambers can be designed as metering cylinders to which a piston plate with a respective ejection piston moves relatively for each metering antechamber, so that the pre-metered melt quantity is introduced identically and at the same time over the shortest possible path into all mold cavities. In this case, it is possible that the introduction of the melt into the cavities is controlled to be intersecting with the retraction movement of the cores into the cavities. By the way of the ejection piston the pre-metering quantity is determined. By using different diameters and lengths of the metering cylinder and the ejection piston large jumps can be made in relation to the Dosiermengen, for example, for particularly large or thick preforms.

According to a particularly advantageous embodiment, this dosing antechamber is additionally preceded by a shrinkage compensation chamber for each mold cavity, so that during the first shrinkage phase of the preform still melt can flow into the mold cavity. During the shrinkage compensation by the valve, the input into the shrinkage compensation chamber is closed.

According to a further advantageous embodiment, the metering of the melt can take place in the mold cavity itself. The cores are controlled so far introduced into the cavities until a pre-definable dosing set is. This presupposes that the movable tool carrier plate for the metering position is positionally and weggesteuert / -geregelt, so that adjusts a desired metering in the cavity. Already with a melt pressure of more than 20 bar, the mold cavity can be filled in essentially any repeatable way and thus the exact pre-metering of the melt quantity can be achieved. A high metering pressure of, for example, 50 to 250 bar, preferably 100 to 200 is required so that the melt can be introduced at high speed into the most distant cavity areas of the cavity, in particular the threaded portion of the preforms, and further that all cavities have the same filling conditions to have. Fast filling prevents premature local cooling of the melt in the edge area of the cavities.

In contrast to the relatively low dosing pressure, usually less than 200 bar, the compression pressure should be brought to 300 to 600 bar. For this purpose, the new solution takes advantage of the compression pressure very much advantage. A plasticizing screw itself, since it primarily has the task of melt processing, a pressure pump with a poor efficiency. In contrast, the mechanical pressure generation during compression molding with the cores is optimal in relation to the required energy.

Brief description of the invention

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

FIG. 1 shows a schematic overview of an injection molding machine for the production of preforms of the prior art; FIG. 2a shows the tool and injection side of a device according to the invention; FIGS. 2 b to 2 e show four different positions of the tool or of the tool

Positive connection of an inventive injection molding machine.

FIG. 2b shows a start position with open shapes. The Figure 2c shows the neck rings, already retracted. FIG. 2d shows the end of the pre-metering, and FIG. 2e shows a situation in the compression phase; the form drive with toggle levers and a closed

Mold; schematically the angle range α for the closing process until the end of the filling or dosing; the angular range β of the compression phase; c three positions when retracting a neck ring and a core into a cavity; Figure 4a shows the neck ring and the core in the retracted position; in Figure 4b, the neck ring is already in a sealing position; in the figure 4c, the core is retracted in a metering position; g seven positions of a whole injection cycle; e five positions for the dosing or mold filling process with a dosing chamber upstream of each cavity and a shrinkage compensation chamber; c schematically three positions for the metering and the compression phase; schematically shows the melt supply into the cavity with a Dosiervorraum and a shrinkage compensation space for the melt for a preform; shows a second adjustable stop; shows a first adjustable stop; schematically shows an injection molding machine with vertical

Ax; a combination of an inventive solution with an extruder and a Fi-Fo-melt storage. Ways and embodiments of the invention

1 shows an entire injection molding machine of the prior art for the production of preforms 10 with a machine bed 1, on which a fixed tool carrier plate 2 and an injection unit 3 and a support plate 4 are mounted. A movable tool carrier plate 5 is supported axially displaceably on the machine bed 1. The fixed tool carrier plate 2 and the support plate 4 are interconnected by four bars 6, which enforce the movable tool carrier plate 5 and lead. Between the support plate 4 and the movable tool carrier plate 5 is a drive unit 7 for generating the closing movement and the closing pressure. The fixed tool carrier plate 2 and the movable tool carrier plate 5 each carry a mold half 8 and 9, in each of which a plurality of cores 24 and cavities 60 is arranged, which together form the mold cavities for producing a corresponding number of sleeve-shaped injection molded parts. After opening the mold halves 8 and 9, the sleeve-shaped injection-molded parts 10 adhere to the cores 24. The preforms 10 are still in a semi-solid state at this time and are indicated by broken lines. The same injection-molded parts 10 in the finished cooled state are shown in FIG. 1 at the top left, where they are just dropped from a post-cooling device 19. The upper spars 6 are shown interrupted for the purpose of better showing the details between the open mold halves.

FIG. 1 shows the four most important handling phases for the preforms 10 after completion of the injection process:

"A" is the removal of the injection molded parts or preforms 10 from the two mold halves 8, 9. The still semi-rigid sleeve-shaped parts are thereby received by a in the space between the open mold halves 8, 9 and a lowered into the position "A" removal device 11 and with this in the position "B" raised (receiving device 11 'in Figure 1).

"B" is the transfer position of the removal device 11 with the preforms 10 at a transfer gripper 12 ("B" in Fig. 1). "C" is the transfer of the preforms 10 from the transfer gripper 12 to a

Nachkühleinrichtung 19. "D" is the discharge of the cooled and brought into a dimensionally stable state

Preforms 10 from the Nachkühleinrichtung 19.

FIG. 1 shows, as it were, snapshots of the four main steps for handling after removal from the mold halves 8, 9. In the position "B", the sleeve-shaped preforms 10 arranged vertically one above the other are taken over by the transfer gripper 12 or 12 'and by pivoting the transfer device in the direction of the arrow P in a position horizontally next to each other, according to the phase "C" brought. The transfer gripper 12 consists of a pivotable about an axis 13 holding arm 14, which carries a holding plate 15 to the parallel spacing a support plate 16 is arranged for cores 24. The support plate 16 can be raised by means of two hydraulic devices 17 and 18 parallel to the holding plate 15, so that in the position "B" the sleeve-shaped injection molded parts 10 are retrieved from the removal device 11 and pushed by the pivoted to the position "C" position in the overlying Nachkühleinrichtung 19 can be. The respective transfer takes place by increasing the distance between the holding plate 15 and the support plate 16. The still semi-rigid preforms 10 are ready-cooled in the aftercooling device 19 during three to four cycles and then, after a displacement of the Nachkühleinrichtung 19, in the position "D" expelled and thrown on a conveyor belt 20.

FIGS. 2a to 2e show the solution according to the invention. In the figure 2a, the cores 24 are extended. The tool is in open position. The movable tool carrier plate 5 is at the far left. Analogously, the neck rings 62 are shown with the Neckringträgerplatte 80 in disengaged position, immediately after the removal of the preforms of a previous injection cycle. The neckring support plate 80 is supported or guided on the movable tool carrier plate 5 and can perform its own driving movement via a drive 23, not shown. With The movable tool carrier plate 5 is fixedly connected to a core carrier plate 81, so that the cores 24 are moved directly with the positive locking. The mold cavity 82 may also be slidably guided on the spars 6. Immediately on the fixed tool carrier plate 2 is a hot runner plate 83, which is part of a two-part tool, consisting of the hot runner plate 83 and the mold cavity 82. These two plates are relatively displaceable. As will be explained below, with the corresponding relative movement, melt can be metered into the mold cavities. The mold cavity 82 can be moved for this purpose by a drive 23 which is supported on the movable tool carrier plate 5. The drive 23 presses the cavity plate 82 in the direction of the hot runner plate 83, wherein a spring 84 is tensioned (Figure 2b). With the relaxation of the spring 84, the mold cavity 82 is moved to the left and filled a Dosiervorraum 70 with new melt during the opening movement of the positive connection. Instead of the spring 84, any drive, such as a throttled hydraulic cylinder can be used. The injection unit 3 according to FIG. 2a consists of a plasticizing unit 31 with a plasticizing screw 32, a feed hopper 26 for the granulate feed and an injection nozzle 28 with corresponding drives 35. 33 denotes a reservoir for additives which are metered into the plasticizing space by means of a pump 34 , It is important that with a plasticizing screw 32 in the zone X a good mixing is achieved. The plasticizing screw 32 performs by means of motor 35 a rotary movement and a linear displacement. The entire injection unit 3 can be moved horizontally, as indicated by arrow 36, so that the injection nozzle 28 is moved into or out of contact with the hot runner plate 83.

Figures 2b to 2e show four successive situations for the compression molding according to the new invention. FIG. 2b shows the injection molding tool in the starting situation for one injection cycle, wherein the mold halves are open and the cores 24 are in the retracted position. FIG. 2c already shows the preparation of a spraying cycle. The neck rings 62 have penetrated into the inlet region of the cavities 60 and close the corresponding outer edge. The valve is still in closed position.

FIG. 2d shows, as a subsequent step, the metering process, the first phase of the injection process. The cores 24 are retracted, as shown by arrow 85, into a filling or metering position of the cores 24 within the cavities 60. At the same time, this is the beginning of the melt dosage into the cavities 60 according to arrow 86.

FIG. 2e already shows the compression phase as a third phase. The cores 24 are pressed according to double arrow 87 by a compression path in the cavity 60 with filled melt. The valves are already closed. After the start of the compression phase, a new dosing quantity is prepared for the next injection cycle.

FIG. 3a shows the form-locking side with the two tool halves 8, 9 in the closed position. The drive support plate 4, together with the toggle mechanism 40 and the movable tool carrier plate 5, a horizontally displaceable assembly. The horizontal displacement is accomplished by a column nut adjustment and primarily needed for adaptation for different thicknesses. The toggle mechanism 40 consists of a crosshead 41 and four tab connections 42, further comprising four 5-point toggle levers, each of the 5-point toggle lever having a first toggle lever 43 and a second toggle lever 44. Both are connected via a common knee joint 45. The knee lever 43 are connected via bearings 46 at articulation points 47 with the drive support plate 4. The knee lever 44 are connected via bearings 48 at articulation points 49 with the movable tool carrier plate 5. The crosshead 41 is via the tab connection 42 via joints 50 and 52 with the respective knee levers 43 in engagement. The tab connection 42 may be formed as a longer lever, so that the power transmission ratio is improved. The toggle drive 55 consists of a cylinder 56 and a piston rod 51. The cylinder 56 is connected via a flange to the crosshead 41. The Piston rod 51 has a piston rod end bearing 53, which is connected via a piston rod abutment 54 with the drive support plate 4. FIG. 3b schematically shows an angle range α for the closing process until the end of the metering phase. FIG. 3c shows the angular range β of the compression phase.

Figures 4a to 4c show schematically three situations when retracting a core 24 and the neck ring 62, 62 ', 62 "in a cavity 60. The cavity 60 is determined in the cylindrical part by a cooling sleeve 61. In the area of the open end side of the preform the outer contour, in particular the entire threaded portion of the preform 10, is determined by a neck ring 62. The entire inner shape of the preform 10 is formed by the core 24 (Figure 4c). The core 24 moves with the movable mold half 8 in a horizontal direction. The same applies to the neck ring 62, 62 ', 62 ", as far as the retraction movement into the cavity 60 is concerned. In order to free the threaded portion of the preform 10, the neck ring 62 must be split so that the two halves can move transversely to the horizontal motion, as shown in FIG. 4a. At the beginning of an injection cycle, the neck ring 62 is first closed and closed to the cavity 60 until a tight seal is achieved (FIG. 4b). Finally, the core 24 moves into the cavity 60 (Figure 4c).

Figures 5a to 5g show seven situations according to the new solution with the compression molding method. FIGS. 5a and 5c correspond to FIGS. 4a and 4b. FIG. 5 c (notwithstanding FIG. 4 c) shows that the cores 24 are not yet completely retracted into the cavity 60. FIG. 5d shows the same core position as in FIG. 5c; however, a metered amount of melt (dotted) has already been injected into the cavity 60. The compression phase is expressed in FIG. 5e (preform black). For this purpose, the core 24 is completely pressed into the position in which the preform 10 receives the final injection mold. FIG. 5f shows the core 24 already extended and FIG. 5g shows the release of the preform 10.

Figures 6a to 6e show a preferred embodiment in which the melt is predosed before injection into the cavity 60. The dosing room 70 has a cylindrical shape, so that a corresponding piston 71 analogous to a piston pump can make a presettable displacement movement.

In FIG. 6a, the metering antechamber 70 is filled. In this case, the injection opening 103 is closed with the valve needle tip 104. Simultaneously with the filling of the metering antechamber 70, a shrinkage compensation chamber 75 also remains fully filled. The core 24 is already moving into a metering position. The metering antechamber 70 is preceded by a shrinkage compensation chamber 75.

According to Figure 6b shows the beginning of the dosage. The metering antechamber 70 and the shrinkage compensation chamber 75 are filled.

FIG. 6 c shows the actual filling phase or metering phase of the cavity 60. The valve needle 73 is retracted to the right. The injection nozzle 74 is open. The filling opening 115 is closed with the rear valve seat 106. The piston 71 is already shifted to the right according to arrow 116 and is in the process of displacing the melt in the metering antechamber 70 and metering it into the cavity 60.

FIG. 6d shows the phase of the shrinkage compensation after the compression phase. The valve 106 is in the retracted position and closes the filling opening 107. The compression pressure prevails both in the shrinkage compensation chamber 75 and in the cavity 60. A compensating flow, at least during the first cooling or shrinking phase of the preform 10, takes place via the free connecting passage 117 , Thus, the shrinkage is compensated by the melt under compression in the heated shrinkage compensation space 75.

FIG. 6 e shows the situation at the end of the cooling or shrinking phase. The valve needle tip 104 has already closed the injection opening 103. The metering antechamber 70 and the shrinkage compensation chamber 75 can be refilled for the next injection cycle. The great advantage of a solution according to FIGS. 6a to 6e lies in the fact that during the mold opening and closing of the mold again a pre-metered amount of melt can be provided. This results in a time saving for an injection cycle of 1 to 3 seconds. With a preform with 4 mm wall thickness and 25 grams of weight is expected in the latest state of the art with about 14 seconds cycle time, with the hold time about 6 seconds and the remaining cooling time about 3 seconds. The shrinkage can be up to 8% in extreme cases. The dosing phase itself can be reduced to 1/2 - 1 second. Once the optimum, freely preselectable closing position has been reached (FIG. 6b), the injection of the melt from the chambers into the cavities 60 must be initiated. Exactly at this "switching point" has the closing unit on a damping of any kind (Figure 2b), such as a spring 84 to drive, which generates a higher back pressure against the closing forces than needed for injecting the melt from the melt chambers for filling the cavities 60 Hydraulic cylinders would be conceivable, which would accompany the entire stroke and close the valve in the desired position by means of a displacement transducer.These cylinders could also absorb the closing movement in a short construction to initiate the injection stroke, but after the injection process this would be a complete closure If the closing unit moves to the said damping, the force builds up on the piston plate and the melt is now forced into the cavities 60 (FIG.

When the end position of the individual pistons is reached, the damping is released again, with the existing closing force, as already mentioned, to completely close the mold and to pressurize the enclosed melt in the respective cavity 60 for the "compression molding" The dimensions of the individual pistons or chambers must be designed such that the closing force can generate the required pressure for injecting the melt into the cavities 60. The now substantially identical amounts of melt in the individual cavities 60 and the remaining melt chambers is in all cases Cavities 60 a same melt pressure during the holding pressure phase, which compensates for the shrinkage caused by volume shrinkage of the melt new solution, the melt path between the dosing antechamber 70 and the respective cavities for each cavity is identical. This, in contrast to the hot runner plate of the prior art. This results in preforms 10 under optimum conditions and with the highest qualities.

After completion of the cooling time, the tool is opened in a known manner. With the opening stroke of the closing unit, the refilling of the melt chambers can be initiated at the same time and the damping can be returned to its starting position, depending on the design. The piston plate is pushed by the inflowing melt back into a presettable position. The closure needles are controlled such that they keep the nozzles closed during the filling process in order to prevent the melt from flowing into the cavities 60 due to the filling pressure (FIG. 6e).

It can be assumed that the closing forces are significantly lower than those of the prior art, for example in accordance with WO 2004/073953. Investigations revealed a force requirement of only 5 to 10 KN / cavity. Based on this insight, it may be assumed that the system manages with one third of the closing force.

A shot pot can basically be dispensed with with the new solution. Advantageously, a much cheaper extruder can be used in conjunction with a Fi-Fo melt storage according to patent application no. 0268/08 25.2.2008. In principle, energy is saved on both solutions, since the injection process is no longer performed by a separate drive but by the already existing closing movement. The content of this application is explained as an integral part of the present application. The piston plate must be designed so that it can be heated with integrated cartridges. These can be arranged, for example, in the pistons or heating plates in a sandwich construction. It is also important to ensure that the leakage material, which is likely to occur in chip form, can fall out of the individual pistons free. The cleaning process Hesse fine air ducts in the piston significantly improve from which the Leckagematehal can be blown out at intervals still to be determined by means of air blasts. The amount of leakage late neck will be very small anyway due to the small expected pressures as described above. In addition, this amount can be determined constructively by the design of the gap. Without leakage, however, can not be worked because the material also acts as a lubricant.

When cavities damage can be moved to the state of the art. The nozzle needle is frozen in the "nozzle closed" position, which forces the material for the damaged cavity in the melt chamber back into the hot runner in the hot runner instead of in the cavity.

Figures 7a to 7c show the metering and the compression phase. In FIG. 7 a, the cavity 60 is used as a metering antechamber 70 by a predetermined retraction of the core 24. On the open end side of the preform 10, the cavity 60 is substantially sealed by the neck ring 62 and the core 24. According to FIG. 7b, the melt is injected into the cavity 60 at a preselectable melt pressure and the valve is closed at the metering end (FIG. 7c). Only now does the compression phase begin, in which the core 24 is pressed into the cavity 60 with full closure force and the melt is compacted. To the injection nozzle 28, a nozzle heating belt 63 is arranged.

FIG. 8a shows a particularly advantageous embodiment of the melt dosage according to FIGS. 6a to 6e. The device has for this purpose a metering antechamber 70 which is connected to a melt transfer channel 100 and an extruder, according to arrow 101. Within the Dosiervorraumes 70 and a melt channel 102, a valve needle 105 is arranged, which according to Figure 8a, the injection port 103 with the valve needle tip 104 closed. On the right half, the valve needle 105 has a valve body 106, which closes the valve seat 107 in the opposite position. The valve needle 105 is actuated by a piston 108, which within a cylinder 109 by means of a Pneumatikmediunns 112 and valves 110 and 111 is controlled in the required cycle of the injection cycle. The pneumatic medium 112 is shown with larger dots and the melt with fine dots. The melt is heated, at least in the metering antechamber 70, in the melt transfer channel 100 by means of heating elements 113. FIG. 8a shows an interplay between refilling the metering antechamber 70 and transferring the metering chamber volume into the cavity 60. For this purpose, the entire device 114 moves to the right. Because the melt transfer into the cavities 60 takes place independently of the flow in the melt transfer channel 100, the time previously required for filling the cavity 60 can be saved. This time saving can be on the order of 1 to 4 seconds, which means a considerable increase in productivity with a total cycle time of, for example, 12 seconds.

FIG. 8b shows the arrangement of two adjustable wedges 64, 65 between the hot runner plate 83 and the plate 67 as a second stop. By adjusting the two wedges 64, 65, the second stop can be adjusted, this by means of a controlled drive 66. With the second adjustable stop the exact dosage or the way of Dosierkolbens 71 can be preset.

With the first stop according to FIG. 8 c, at the end of the metering position, the path is released via the hydraulic cylinder 68 for the compression phase.

FIG. 9 shows diagrammatically a Sphtzgiessmaschine with vertical axis 120. From the function, however, correspond to all parts of a machine with a horizontal axis.

FIG. 10 shows a combination of the new invention with an extruder 89 and a multiplicity of miniature shot pots 90, whose most important components are: a metering antechamber 70, a valve needle 105, displacement piston 95 and a pneumatic cylinder 109. The extruder 89 performs a constant rotating movement out. The displacement piston 95 performs primarily a linear movement in the rhythm of the injection cycle. Analogously, the displacement piston 95 moves in time with the piston 108 and the valve needle 105. Additives 33 can by means of a Pump 34 are supplied to the plasticization.

The extruder 89 may be shorter than the plasticizing screw 32 according to FIG. 2a. The extruder 89 consists of an extruder screw 91 and an extruder barrel 92. The granules are fed via a feed hopper 26 to the extruder 89. The drive motor 93 may be a simple electric motor, since it only has to ensure a rotary movement for the extruder screw 91. The peculiarity of this solution is that immediately after the extruder 89 a Fi-Fo memory 94 is arranged. The fi-fi accumulator 94 has the peculiarity that the melt leaving the extruder 89 first also leaves the Fi-Fo accumulator 94 first and is fed into the melt transfer passage 100. In time with the filling process of the miniature shot pots 90, 70, a displacement piston 95 moves according to arrow 96 from top to bottom and vice versa. The displacement piston 95 is primarily axially driven, but may additionally perform a rotary motion, especially if it is a mixer. The Fi-Fo function also applies to the melt flowing directly from the extruder 89 into the Fi-Fo reservoir 94. When discharging the melt from the Fi -Fo storage 94 flows the melt from the extruder 89 as a parallel flow with the Extruderaustrag and is fed directly into the dosing Vorraum 90, 70.

Claims

claims

1. A method for compression injection molding of preforms (10) by means of an injection molding machine with a movable tool carrier plate (5) with a mold half (8) with cores (24) and a fixed tool carrier plate (2), which has a mold half with a plurality of mold cavities (60), wherein the melt on the side of the stationary tool carrier plate (2) metered via controlled valves in the mold cavities or in the cavities (60) is introduced and the cores (24) so far in the cavities before completion of the melt dosage (60), that the cavities (60) are at least substantially closed to the outside, that is, that the cores (24) have a filling or a filling around the cores (24) to produce a ring flow Take the metering position and the melt for each cavity (60) is introduced in a pre-metered amount.

2. The method according to claim 1, characterized in that, prior to the melt metering, a neck ring (62) moves toward each of the mold cavities, which close off the cavities (60) in an annular manner to the outside.

3. A method according to claim 1 or 2, characterized in that, for each weft, the quantity of melt pre-metered for a preform (10) is prepared for each mold cavity in a respective metering antechamber (70).

4. Method according to one of claims 1 to 3, characterized in that the predosing is co-determined by a double valve with controlled movement associated with each mold cavity (60) or the metering antechamber (70), which injector controls the injection valve the mold cavity or cavity (60) and the supply to the metering antechamber (70) cyclically opens and closes.

5. Method according to claim 4, characterized in that each dosing antechamber (70) is preceded by a shrinkage compensation chamber (75), the injection valve back being provided for opening and closing the supply to the shrinkage compensation chamber (75), so that the shrinkage of the preform (10) melt from the shrinkage compensation space (75) can flow into each mold cavity (60).

6. Method according to one of claims 1 to 5, characterized in that the introduction of the melt into the cavities (60) is controlled to be intersecting with the movement of the cores (24) into the cavities (60).

7. Method according to one of claims 1 to 6, characterized in that the final metering quantity is adjustable as a function of a selectable metering pressure or reprinting in the mold cavity (60) and in the shrinkage compensation chamber (75).

8. Method according to one of claims 1 to 7, characterized in that the metering pressure can be set in a range from 50 to 250 bar, preferably from 100 to 200 bar.

9. Method according to one of claims 1 to 8, characterized in that the melt in the cavity (60) is compacted with a compression force of 5 to 10 KN / cavity, with a subsequent holding pressure phase.

10. A method according to any one of claims 1 to 9, characterized in that the neck rings (62) are moved and driven relative to the cores (24) by means of a neck ring plate (80) such that the neck rings (62) as the first outwardly form a seal around the open edge of the cavities (60).

11. A method according to any one of claims 1 to 10, characterized in that the cores (24) have a rear cylindrical portion such that the cylindrical portion in a corresponding bore of the neck rings (62) over the required displacement forms a tight seal for the compression phase.

12. Method according to one of claims 1 to 11, characterized in that the entire compression pressure occurs mechanically via the positive connection or the cores (24), the dosing phase preferably passing into the compression phase without stopping the core movement ,

13. A device for compression injection molding of preforms (10) by means of an injection molding machine with a movable and a stationary tool carrier plate (2 bzw.5) with a mold cavity (82) having a plurality of mold cavities (60), wherein the movable mold half (8 ) is formed with a core support plate (81) and with cores (24), the melt supply in the mold cavities (60) on the side of the stationary tool carrier plate (2) and the injection valve to the mold cavities (60) valve controlled is lockable, I net net, that by means of the cores (24) the open Preformseiten are lockable to the outside and the device has a control device for positioning the core carrier plate (81) or the cores (24) in a metering position and pre-metered amounts of melt into the cavities (60) can be introduced, wherein the compression pressure for the production of the part shape in the individual cavities (60) via the cores (24) can be generated.

14. Device according to claim 13, characterized in that the individual metering antechambers (70) are designed as metering cylinders in which a piston plate with one ejector piston for each metering antechamber (70) is relatively movable, so that the in The quantity of moles pre-metered into the metering cylinders can be introduced identically and at the same time into all mold cavities or cavities (60).

15. The apparatus of claim 13 or 14, ad d u rch e ken nzeich net that it is designed as an injection molding machine with horizontal axis and horizontally movable tool carrier plate or with vertical axis and vertically movable tool carrier plate.

16. Device according to one of claims 13 to 15, d ad u rch ge I mean net that it is designed as an injection molding machine with a vertical axis and vertically movable tool carrier plate.

17. Device according to one of claims 13 to 16, d ad u rch ge ken nzeich net that the drive of the movable mold half (8) via toggle (43, 44) takes place and the compression pressure within 12 ° to the dead center of the toggle lever ( 43, 44) can be generated.

18. Device according to one of claims 13 to 16, d ad u rch ge I mean net that it has a positive connection with a hydraulic or an electric or a linear drive.

19. The device according to claim 13, wherein the movable tool carrier plate is associated with a neckring carrier plate movable relative to the cores.

20. Device according to one of claims 13 to 19, d ad u rch ge I mean net that the stationary tool carrier plate (2) is associated with a two-part tool.

21. Device according to claim 20, characterized in that the two-part tool consists of a stationary hot runner plate (83) and a mold cavity plate (82) which is movable relative to it.

22. Device according to one of claims 13 to 21, d ad u rch ge I mean net that the movable mold cavity plate (82) from the side of the movable tool carrier plate (5) is drivable.

23. Device according to one of claims 13 to 22, ad d ing ge chen Ize net, that each of the mold cavities (60) in the mold cavity (82) a Dosiervorraum (70) is assigned to the shot-wise preparation of the predosed amount for each individual cavity (60).

24. Device according to one of claims 13 to 23, d ad u rch ge I mean net, that between the mold cavity (82) and the hot runner plate (83) a preferably adjustable damping, for example, an oil throttle is arranged.

25. Device according to one of the claims 13 to 24, characterized in that between the piston plate (67) and the hot runner plate (83) and / or between the movable tool carrier plate (5) and the hot runner plate (83) an adjustable stop is arranged.

26. Device according to one of claims 13 to 25, characterized in that there is associated with each mold cavity or cavity (60) a double valve with a valve needle (105), the valve needle (105) resting on the valve needle (105) Side of the cavity (60) has a valve seat (107) for opening and closing the injection port (103) and on the opposite side a valve body (106) to open and close the inlet opening (103).

27. The device according to claim 13, wherein the device is used in combination with an extruder and a fused-melt reservoir (FIG. 10).