DE10005264C1 - Multicomponent pressure injection molding employs melt stores with pistons separating the main- from secondary components, causing injection by use of main component as a hydraulic fluid - Google Patents

Abstract

The invention relates to the production of multi-component plastic shaped parts, which are comprised of a main constituent and of at least one minor constituent, on an injection molding machine. Said injection molding machine is equipped with a main aggregate, which is configured as a plasticizing and injecting unit and which is provided for preparing the main constituent, and is equipped with an auxiliary aggregate for preparing the minor constituent. According to the invention, the highly viscous minor constituent (19) is prepared by the auxiliary aggregate (17) and is fed to a storage space (10) of a melt reservoir (8) that is assigned to said auxiliary aggregate (17). The highly viscous main constituent (18) is prepared by the main aggregate (6) and is fed to a pressure space (11) of the melt reservoir (8). The minor constituent (19) and the main constituent (18) are dosed by a displacement measuring device of the main aggregate (6). The minor constituent (19) is stored in the storage space (10) and the main constituent (18) is stored in the pressure space (11) while being separated from one another by a sealing plunger (9) of the melt reservoir (8). The minor constituent (19) contained in the storage space (10) and the main constituent (18) contained in the pressure space (11) of the melt reservoir (8) are injected, optionally in succession or simultaneously, with the hydrostatic injection pressure of the main constituent (18) of the main aggregate (6) into a tool cavity (20; 21; 22).

Description

The invention relates to a method for producing Multi-component molded parts made of plastic, consisting of a main component and at least one secondary compo nente, on an injection molding machine with a plastic Ornamental and injection unit trained main unit for the provision of the main component and at least an auxiliary unit for the provision of secondary comm component and a device for performing this Procedure.

The components to be processed are both for plastic melts, as well as chemically reactive hige, as well as liquids that together or time in different order, with which Plastic melt can be injected into a tool and if necessary chemically with the plastic melt react. The components to be processed can with regard to their properties, such as viscosity, process Differentiate processing temperature and compatibility. From DE 39 32 416 C2 a method is known in which Generate several for one injection cycle separately te plastic melts in front of at least one sprue or the entrance opening of a sprue system Mold first in a egg in the exit area ner suitable injection unit arranged collection room in a disc-like arrangement perpendicular to the longitudinal axis the injection unit must be deposited before it is delivered after the Structure of the complete filling quantity for the mold in the collecting room overall with a single stroke of Injection unit through the sprue or the entrance opening the sprue system into the mold be injected. The disc-like arrangement the plastic melts in the collecting space by suitable  Selection and layering of the plastics used testifies that in the already melted state in the Collection room. The specialist should the hint given how several differed Liche and already melted plastic melts in a collection room in an injection mold end of an injection cylinder or an extruder can be deposited in layers, and then without noticeable mixing with a stroke of the injection unit to be pressed into the injection mold.

The application of this procedure is however out chose plastics whose layers are deposited nation in the common collecting room no mutual Influences on the contact surfaces, for example Temperature compensation, or chemical reactions fear let it. There is also some mixing of the ver different components in the common collecting room to exclude. The use of mechanical separation slices cannot provide a thorough remedy, because as a result of the filling grooves and through openings which pressed the components, with vortex formation mutual influences of the components cannot be prevented.

All plastic components, regardless of their different properties, under the same one spray conditions such as pressure, temperature and speed speed, injected.

Furthermore, the order of injection is the compo can only be selected to a limited extent, since the main component in the must be injected last. Chemically with reacting to each other or with the plastic melts Liquids cannot be processed.

In the device for performing the method according to DE 39 32 416 C2, the plasticizing units are on in any case connected to a common collecting room, the one selected in the exit area of a single  Injection unit is arranged. The flow of all art melted components is caused by the movement of the Auger piston realizes the volume of the common seed collecting space reduced. The positioning of the Collection space is due to that for the injection necessary forces by mechanical transmission limbs are transferred and a correspondingly large Make dimensioning necessary.

The object of the invention is to avoid or Mi minimizing the disadvantages described, a method and an apparatus for performing this method to demonstrate that processing the most diverse Materials and in a freely selectable order possible lichen. Furthermore, the individual components should be under processing conditions that are optimal for them can be worked.

The object is achieved by the in claim 1 specified method and be in claim 4 written device.

The method according to the invention enables processing processing of different materials with one Injection unit. The main and the secondary component who initially in mechanically separated rooms Men provided for injection. Plastic melt, also chemically reactive, as well as liquid that are suitable with the melts at to react chemically, at the same time or in selectable order, with the hydrostatic pressure the main component is injected with a touch the components together when injecting, un is done indirectly in front of the tool cavity. Corresponding their different chemical and physical Properties as well as the conditions of the process and the device, the individual components  Injection molding devices are also known, in which axially movable control pistons, torpedoes or cuffs, from pressure individual plastic components moved, selectively flow paths open and close with multi-component injection molding. These devices are used for simultaneous and / or consecutive merging of under different melt flows. The movable ones used for it Arranged elements are line by fluidic drive be, partly moved by melt, namely by a pressure difference referencing itself from the respective end faces acting pressures results in a resulting Force that moves the pressure-controlled elements triggers. The movements selectively melt channels released and blocked.

Three such devices are described below ben.

Thus, in the injection molding device according to EP 0 748 677 A1, the manufacturing and maintenance costs for the tax reducing in the nozzle head, a control piston with several ren control edges within a formed in the nozzle head Control chamber mounted longitudinally displaceable, with which, depending depending on the pressure of the skin or core material skin or core material can be controlled via the nozzle head and the supply of the plastic material that is not being conveyed (Skin or core material) is lockable.

An injection molding tool is known from DE 197 57 411 C1, which has, among other things, a controllable device, which optionally the first feed channel with separation of the second feed channel directly with the outlet opening connects or decouples. The controllable facility will from a slidably arranged in the first feed channel, tubular piston element formed, one by the Fluid pressure can be acted upon in the first feed channel Piston area and one by the fluid pressure in the second Feed channel has acted upon second piston surface. Depending on the stronger fluid pressure in the first or second Feed channel is the piston element in different switching  positions for closing or opening the first and / or second feed channel slidable. An axial passage Opening of the tubular piston element is a component of the first feed channel and coaxial to the valve pin arranged. It can be opened and closed with the locking needle close.

From DE 24 45 112 A1 is a spray nozzle arrangement obviously, which has a single feed channel, which opens laterally from the form and at least three separate ones Has chambers, each separated and coaxial la are arranged to each other. Each chamber is with one independent feed line for a material connected ches to be injected and has a unit for Pressing on.

A disadvantage of the three devices described above gene is that they are severely restricted in their application are. Either they are part of the injection mold or the injection unit. A simple installation between the nozzle-side tool carrier plate and the nozzle-side Half of the tool is not possible.

The provision of a defined melt volume for the Skin components are not possible with these devices. They are therefore not suitable for storing and dosing. The movable elements of the devices mentioned act only as separating or control elements, but not for displacement supply of the melt in the sense of its promotion.

An increase in injection pressure due to a pressure over Settlement cannot be achieved with these devices. In the three devices described above one for each injection of different melts Injection unit needed for every material.

The control and dosage as well as the timing, at for example for the simultaneous phase, in the skin and core comm component must be sprayed at the same time through the spray casting machine.  

under each of them optimally adapted conditions mounted and injected.

According to an advantageous embodiment of the invention According to the method, the hydro is transmitted static injection pressure of the main component the secondary component via a sealing piston where every time you touch the components is closed.

This is also an advantageous embodiment of the process according to the invention to see that, as required, several secondary components and only one main component in a process for the production of multi-component Molded parts are provided and injected. This makes it possible to make molded parts with a lot of difference lichen properties, what the range of use the procedure significantly increased.

The inventive device according to claim 4 enables the production of multi-component molds share according to the method according to claim 1 with the advantages shown.

According to an advantageous embodiment of the Invention according device are several auxiliary units and just as many melt stores assigned to them exist the. This allows the device to be used for the production from different components standing multi-component molded parts are enlarged. Not all existing auxiliary units and associated ones Melt storage must be in the manufacture of the more molded components are used. This can cause a necessary to convert the device to the Production of other products will be accelerated. This is also an advantageous embodiment hen that the melt memory is not in the injection axis must be arranged, but also parallel or can be arranged at any angle to it because the injection pressure does not have mechanical links  hydrostatically via appropriately dimensioned Transfer connecting lines and melt storage becomes. This results in advantages in terms of Mastery of the occurring forces, but also in loading train on the user-friendly accessibility of the Melt storage in case Pa becomes necessary parameter changes or product changes.

There is also an embodiment of the fiction moderate device in that the backflow of the Auxiliary component in the auxiliary unit by a back check valve is prevented.

According to a further embodiment, connections are channels provided in the melt memory that the overflow the main component to the tool possible. This makes it possible to use the main component before the secondary component or before the secondary components into the tool. It is also possible Lich, the main component also concluding to inject.

The connection channels are expediently through the piston opened or closed to the main control component. The main component and the Auxiliary component can be in a common tool cavity as well as in separate tool cavities be injected so that after the sandwich and also worked according to the overmolding process can be.

An embodiment of the invention is also included therein see that the piston has a control piston with overflow can be controlled. Such a trained melt storage is particularly then useful if a pressure over the piston setting should be achieved.

Finally, there is also an embodiment of the Invention to see that the piston as a step piston  is formed, resulting in easy adjustment the pressure conditions can be reached.

The invention will now be described in exemplary embodiment len are explained in more detail.

In the accompanying drawing:

Fig. 1: Apparatus for producing Mehrkomponen ten-shaped parts, in a schematic representation;

Fig. 2: melt reservoir, in longitudinal section,

Fig. 3: in other melt reservoir, in longitudinal section,

Fig. 4: further melt storage, in longitudinal section.

The apparatus of Fig. 1 comprises a main unit 6 for providing the main component 18, three secondary units 7 for the provision of three secondary components 19, individually to the auxiliary units 7, three melt memory 8, in the connecting lines from the melt memories 7 cavity to subordinate to the tool 23 of the tool side of the nozzle-side tool half 3 and the ejector-side tool half 4 arranged control devices 12 and check valves 13 in the connecting lines from the auxiliary units 7 to the melt accumulators 8 .

The main unit 6 is designed as a plasticizing and spraying unit. The Liche in the antechamber 25 Liche, plasticized main component 18 is after actuation of the injection piston 17 in the injection cylinder by the screw piston 15 , with the reverse flow lock 16 , first in the middle melt memory 8 , as shown in FIG. 1, and then, for example, in succession the upper melt reservoir 8 and the lower melt store pressed. 8 From Fig. 2 it can be seen that the main component 18 reaches the pressure chamber 11 via the connecting channel 27 in the base body 22 . In the storage space 10 there is the secondary component 19 , which was metered by the auxiliary unit 7, for example a plasticizing unit, as a low-viscosity plastic component, with the aid of a displacement measuring device (not shown) on the screw piston 15 of the main unit 6 . When metering the secondary component 19 into the storage space 10 , the piston 9 has moved from its left end position into the position shown in FIG. 2, pushing the main component 18 out of the pressure chamber 11 into the screw chamber 25 and pushing the screw piston 15 to the right would have. When a predetermined path is reached, the measuring device of the main unit 6 gives a signal to terminate the filling process of the secondary component 19 . The main assembly 6 then plasticizes the main component 18 up to a predetermined plasticizing stroke. If there are several melt stores 8 , the filling processes of the storage spaces 10 take place one after the other, so that precisely defined quantities of the individual secondary components 19 are available. As already explained, the main component 18 is pressed into the pressure chamber 11 in the injection process after actuation of the control 12 , where it strikes the piston 9 . This displaces the secondary component 19 from the storage space 10 into the tool cavity 23 .

In the position of the piston 9 shown in FIG. 2, the main component 18 , without coming into contact with the secondary component 19, can be injected into the tool cavity 23 as the first component after actuation of the control device 12 via the connecting channel 28 .

When the piston 9 has reached its left end position again, the main component 18 can flow into the tool cavity 23 via the connection channel 26 that has now been released. The connecting channel 28 is not available in this case. In sandwich injection molding, the main component 18 forms the core material and the secondary component 19 the skin material. However, if the main component 18 form the skin material, it is in the position shown in Fig. 2 position of the piston 9, without interfering with the side component 19 in contact, after actuation of the control device 12 via the then existing connection channel 28 first into the tool cavity 23 injected. The control device 12 is designed, for example, as a hydraulically or pneumatically operated 2-way valve or rotary slide valve. The check valves 13 prevent the back flow of the main component 18 and the secondary component 19, both when injecting and during the placement. When using several melt stores 8 , for example three as shown in Fig. 1, by pressing the respective control devices 12 , the individual NEN secondary components 19 and the main component 18 can be injected into the tool cavity 23 in the desired order.

Fig. 3 shows another melt memory 8. In an axial bore, the piston 9 receives a control piston 24 , which also has an axial bore. During injection, the main component 18 acts on the calf 9 , which displaces the secondary component 19 from the storage space 10 . The axial bore in the control piston 24 is blocked. When the piston 9 reaches the left end position, it blocks the connection between the storage space 10 and the tool cavity 23 . At the same time, the control piston 24 is actuated and the main component 18 can flow from the pressure chamber 11 through the axial bore in the control piston 24 into the tool cavity 23 . Connecting channels 26 ; 28 are not required. The length and diameter of the piston 9 , the storage chamber 10 and the pressure chamber 11 can be adapted well to the structural installation conditions. In particular, the piston 9 can be designed as a stepped piston with which a pressure transmission can be effected. Basically, there is a possibility of adaptation to the respective properties of the individual components and the processing conditions. The associated melt stores 8 are then designed differently accordingly. Since the melt storage 8 can be easily replaced, a simple adaptation to changed component properties or processing conditions is also possible.

An increase in the pressure of the secondary component 19 is thus achieved, for example, in order to overcome greater flow resistances during injection, such as occur with long flow paths or very thin wall thicknesses of the farm part. It is also possible in this way to compensate for inevitable pressure losses when the highly viscous main component 18 flows from the main unit 6 to the melt reservoir 7 .

Fig. 4 shows a further melt storage 8 , which is used in overmolding multi-component injection molding. The tool with the tool cavities 20 ; 21 is designed in rotary, transfer or slide technology. The melt reservoir 8 is heated by means of a heating device 14 . In principle, all melt stores 8 and connecting lines can be heated. This is a further, easy-to-implement option for optimal adaptation to the respective component properties and processing conditions.

During the injection process, the tool cavity 20 is first filled with the secondary component 19 of the auxiliary unit 7 from the storage space 10 by the pressure of the piston 9 . After the reprint time, both control devices 12 are switched and the tool cavity 21 is connected via the connecting channels 26 ; 27 filled with the main component 18 from the main unit 6 .

In this procedure, the injection and hold pressure time for the secondary component 19 and the main component 18, for example, run in succession. However, parallel injection is also possible if the pressure conditions during the injection process result in a defined filling process.

It is also possible to use the bi-injection method, in which the main component 18 and the secondary component 19 act simultaneously in a common tool cavity 20 ; 21 are injected and the flow fronts collide at a specific point in the farm part.

reference numeral

2

ejector-side platen

3rd

tool half on the nozzle side

4

ejector side tool half

6

Main unit

7

Auxiliary unit

8th

Melt storage

9

piston

10th

Storage space for secondary components

11

Print room for main component

12th

Control device

13

check valve

14

Heating device

15

Snail piston

16

Non-return valve

17th

Injection pistons

18th

Main component

19th

Minor component

20th

Tool cavity

21

Tool cavity

22

Basic body

23

Tool cavity

24th

Control piston

25th

Anteroom

26

Connecting channel

27

Connecting channel

28

Connecting channel

Claims (12)

1. A method for producing multi-component molded parts made of plastic, consisting of a main component and at least one secondary component, on an injection molding machine with a main unit designed as a plasticizing and injection unit for the provision of the main components and at least one auxiliary unit for the provision of the loading Secondary component,
wherein the highly viscous secondary component is provided by the sub-assembly and is supplied to a storage space of a melt store assigned to the auxiliary assembly and the high-viscosity main component is provided by the main assembly and is supplied to a pressure chamber of the melt store,
characterized in that

• - The dosage of the secondary component ( 19 ) and the main component ( 18 ) by means of a Wegmeßein direction of the main unit ( 6 ),
• the secondary component ( 19 ) is stored in the storage space ( 10 ) and the main component ( 18 ) in the pressure space ( 11 ), separated by a sealing piston ( 9 ) of the melt reservoir ( 8 ),
• - Controlled by control devices ( 12 ), in selectable sequence or simultaneously, the secondary component ( 19 ) from the storage space ( 10 ) and the main component ( 18 ) from the pressure space ( 11 ) of the melt reservoir ( 8 ) with the hydrostatic injection pressure of The main component ( 18 ) of the main unit ( 6 ) is injected into a tool cavity ( 20 ; 21 ; 23 ) between a tool half ( 3 ) on the nozzle side and a tool half ( 4 ) on the launcher side.

2. The method according to claim 1, characterized in that the injection of the secondary component ( 19 ) into the tool takes place by the hydrostatic injection pressure of the main component ( 18 ) of the main unit ( 6 ) through the sealing piston ( 9 ) in the melt reservoir ( 8 ) is transferred to the secondary component ( 19 ). 3. The method according to claim 1 or 2, characterized in that for one injection cycle two or more secondary components th ( 19 ) of the same number of auxiliary units ( 7 ), each with its own melt storage ( 8 ) are provided. 4. An apparatus for performing the method according to claim 1, wherein the auxiliary unit is assigned a melt memory, which comprises a storage space for storing the metered by the auxiliary unit th provided secondary component and a pressure chamber for receiving the main component provided by the main unit, characterized that

• - Between the storage space ( 10 ) and the pressure space ( 11 ), which is controlled by the hydraulic pressures when metering the secondary component ( 19 ) and the main component ( 18 ), axially displaceable, the volume ratios between the storage space ( 10 ) and the pressure space ( 11 ) changing the sealing piston ( 9 ) is arranged,
• - A control device ( 12 ) is arranged in the connecting line from the melt reservoir ( 8 ) to the tool cavity ( 23 ),
• - A path measuring device for controlling the metering of the main component ( 18 ) through the main unit ( 6 ) and the secondary component ( 19 ) through the auxiliary unit ( 7 ) on the main unit ( 6 ) is present.

5. The device according to claim 4, characterized in that the sealing piston ( 9 ) for the transmission of the hydrostatic injection pressure of the main component ( 18 ) of the main unit ( 6 ) in the pressure chamber ( 11 ) on the secondary component ( 19 ) in the storage space ( 10 ) the melt storage ( 8 ) is suitably designed. 6. Apparatus according to claim 4 or 5, characterized in that a plurality of auxiliary units ( 7 ) and just as much melt storage ( 8 ) are assigned to them. 7. The device according to claim 6, characterized in that the melt memory ( 8 ) are arranged in, or parallel to or at any angle to the injection axis. 8. Device according to one of the claims 4 to 7, characterized in that a check valve ( 13 ) is arranged in a connecting line between the auxiliary unit ( 7 ) and the melt reservoir ( 8 ). 9. Device according to one of claims 4 to 8, characterized in that in the melt memory ( 8 ) connecting channels ( 26 ; 28 ) for the overflow of the main component ( 18 ) from the pressure chamber ( 11 ) are arranged in the connecting line to the tool. 10. The device according to claim 9, characterized in that the opening and closing of the connecting channels ( 26 ; 27 ; 28 ) by the piston ( 9 ) is controllable. 11. Device according to one of claims 4 to 10, characterized in that the piston ( 9 ) an axially displaceable control piston ( 24 ) with end sealing surfaces and an axial overflow channel for the main component ( 18 ) from the pressure chamber ( 11 ) in the connecting line owns the tool. 12. Device according to one of the claims 4 to 11, characterized in that the piston ( 9 ) is designed as a stepped piston.