WO2001038065A1

WO2001038065A1 - Multi-component injection molding nozzle of an injection molding machine

Info

Publication number: WO2001038065A1
Application number: PCT/DE2000/004053
Authority: WO
Inventors: Karl-Heinz Haberkorn; Volker Reichert; Dieter Lehmann; Bernd Hupfer
Original assignee: Reichert Gmbh Kunststofftechnik & Maschinenbau
Priority date: 1999-11-26
Filing date: 2000-11-15
Publication date: 2001-05-31
Also published as: DE19956898C1

Abstract

The inventive adapter plate (1) for an injection molding machine used for producing injection molded parts, which are comprised of several plastic constituents, comprises a device for controlling and combining, according to the pressure of the melt, the plastic constituents that are provided by plasticizing units. The device consists of a valve piston (25) which is displaceably arranged in the melt cylinder (24) that is aligned with the injection axis (26). In addition, a unit (23) is provided for automatically removing the device from the stationary die half (3). The invention is used in the production of injection molded parts that are comprised of several plastic constituents.

Description

MULTI-COMPONENT SPRAY NOZZLE IN AN INJECTION MOLDING MACHINE

The invention relates to an adapter plate for an injection molding tool of an injection molding machine for the production of injection moldings consisting of several plastic components. Injection molding machines of this type have a fixed, nozzle-side and a movable tool carrier plate, on which the mold halves of the injection molding tool are detachably and exchangeably fastened.

The plastic components provided by two or more injection units are usually passed over an injection head before being injected into the cavity of the injection mold. A major disadvantage of this device is that it is an expensive single-purpose machine.

State of the art

In DE 40 21 856 an injection mold is shown, which should avoid this disadvantage. In particular, this injection molding tool is intended to enable rapid tool replacement. It has a nozzle body, preferably with a plurality of nozzle channels which are connected to injection units, and a nozzle head. The nozzle body is held in a separate mounting plate, which is between the fixed mold carrier plate and the right mold half of the injection molding arranged and preferably detachably connected to both parts. According to a special embodiment of this injection molding tool, it is possible to open or close the annularly shaped nozzle channels in the nozzle head by displacing tubular inserts and a nozzle pin by the respective melt pressure which is caused by the injection units during the injection process.

The nozzle pin is opened by the melt pressure against a spring force. The opening and closing of the annular gap-shaped nozzle channels in the nozzle head by means of the tubular inserts and the nozzle pin can be controlled by measuring the melt pressure by means of pressure sensors in circular melt channels in the nozzle body when predetermined pressure values are reached. Likewise, control after measurement of the cavity pressure by means of pressure sensors is possible. In order to be able to produce thin-walled, sprueless multi-layer molded parts, the melt flows are brought together in a heated multi-channel nozzle shortly before the mold cavity. For this purpose, the nozzle head protrudes into the right half of the mold and nozzle channels open directly into the mold cavity.

A disadvantage of this injection molding tool is that it has to be specially adapted to accommodate the nozzle head and cannot be replaced by a simple one that is commonly used. Furthermore, the manufacture of the nozzle body and the nozzle head is complex and therefore expensive.

Solutions are known in which the injection molding cylinders are connected to the tool via variously constructed adapter pieces. According to DE 35 87 947 T2, a valve element is integrated into this adapter piece, which selectively clears the way for the material from one of the two connected injection units. This valve element is operated externally. An additional drive is required for this. The melt channels are released or blocked by rotating a piston in a cylinder. It is disadvantageous that the melt flow is briefly interrupted when switching. The control edges are not covered or covered. Simultaneous injection, with both plasticizing and injection units are not connected to the tool cavity. There is no hot-cold separation between the device and the tool.

The disadvantages of the above-mentioned solution also have the intermediate plate element according to US 4,710,118, which provides for such adapter constructions to be extended to tools with a plurality of mold nests.

According to EP 0 357 301 AI, the valve element can be rotated in such a way that both material flows can get mixed into the tool. The disadvantage here is that when the melt flows are switched over, the melt flow is briefly interrupted by rotating the piston in the cylinder. The control edges are not covered or covered. Another disadvantage is that an additional drive for actuating the valve is necessary. There is also no hot-cold separation between the device and the tool. From DE 195 21 718 Cl a control piston is known which is mounted in a longitudinally displaceable manner within the control chamber and can be controlled depending on the respective pressure of the plastic component. The control unit is arranged in the nozzle head of an injection molding machine. The control piston has several control edges, which open or close the melt channels in the event of a longitudinal displacement with an additional turning valve operated by turning. This solution has manufacturing disadvantages because it is very complex due to the complicated geometry of the control piston and the bore. Furthermore, an additional closure valve is required, which is actuated by a separate drive. Unintentional mixing of the melts cannot be ruled out because the shut-off valve is arranged so that both melts can mix in the right anteroom when the piston is in the intermediate position. Since the volume between the nozzle outlet and the blocking element is greater than zero, melt mixtures are possible. There is no defined starting position and no position fixing of the piston. The use of the control unit remains limited to the machine nozzle head. Their installation in an intermediate plate is not designed. Presentation of the invention

The invention has for its object to provide an adapter plate with a device that can be manufactured with less effort and with which it is possible to operate existing multi-component injection molding machines with conventional injection molds.

Furthermore, in order to improve the processing conditions and results and to reduce the energy consumption, a better separation of the hot / cold phases of the plastic components and spatial separation of the hot from the cold parts are to be achieved.

The object is achieved by the adapter plate specified in claim 1.

Two or more melt streams are brought together and passed into a tool as an annular layer flow with a core. The device is relatively inexpensive and therefore inexpensive to manufacture. The adapter plate makes it possible to use a wide variety of injection molding tools with customarily designed and dimensioned sprue bushings, for example, otherwise used on single-component injection molding machines, on existing two- or multi-component injection molding machines. For example, a simple injection molding tool can be used for two-component sandwich injection molding on an existing two-component injection molding machine without complex conversions. Since these simple tools usually do not have a heater, the automatic movement of the device in the adapter plate enables a clean separation of the hot and cold phases. The separation is made possible by the spring pushing the sprue bush off the tool after the one injection unit has been moved. The spatial separation of the sprue bush from the tool prevents heat from flowing into the tool to be cooled and reduces heat consumption. In addition, the spring-operated retraction of the devices Intermediate spraying outside the injection mold from the injection mold.

With simple tools without a hot runner, the retraction enables a clean separation between the molded part with the sprue and the device.

With hot runner molds, the retraction causes any melt pressure that may still be present in the hot runner to decrease, should this be necessary. According to an advantageous embodiment of the invention, the valve piston consists of individual step pistons forming the melt chambers, which are simple to manufacture, easy to replace and can be adapted to the respective requirements of the melt pressure-dependent control. Another advantageous embodiment of the invention consists in that the stepped pistons are pressed against the device nozzle by a prestressed spring. As a result, the device automatically remains in the zero position or returns to it. It is also an embodiment of the invention that the stepped pistons are pressed against the device nozzle by spring travel-independent hydraulic drives.

According to a further embodiment of the invention, these hydraulic drives can be controlled independently of the melt pressure prevailing in the melt chambers. Another embodiment of the invention provides that the hydraulic drives can be controlled by the control of the injection molding machine.

Likewise, an embodiment of the invention is that the control pistons are designed to be acted upon and controlled in a combined manner by the spring and the hydraulic drives.

With the above-mentioned configurations of the invention, further control and merging variants of the melt streams can be realized. The stepped pistons form a "pressure balance" with the springs and / or the hydraulic drives with regard to the melt pressure. Depending on the forces acting on the end faces of the step pistons, there is a static balance of forces, which the step pistons each have a defined one Holds position. If the balance of forces is changed, for example by the pressure building up in the melt chamber, the stepped piston moves to the right until the static balance of forces is restored. The left-hand end faces of the stepped pistons lift off from stops and are additionally acted upon by the melt pressure, so that the movement of the stepped pistons is advantageously self-reinforcing. According to another embodiment of the invention, the prestressed step pistons seal the melt chambers against the bore of the device nozzle in their zero position and thus prevent the melt from escaping in an uncontrolled manner. The device remains closed until the melt pressure set for the control is reached. The fact that the mechanical stops limiting the closing movement of the stepped piston also have a sealing function means that there is no advantage that there is no wear-related leakage. As a result of the axial movements of the stepped piston of the valve piston in the melt cylinder, the device can be monitored in a simple manner. The movements of the stepped pistons are recorded via displacement sensors. Signals derived from this record the state of the device and can be fed to a connected controller. Because a further embodiment of the invention provides the possibility of connecting the melt chambers individually or together with the bore of the device nozzle, both a melt or one of several alone or two or more can be injected simultaneously or in succession. This creates a wide range of variations in the use of the injection molding machine and the injection molding tool. An advantageous embodiment of the invention can also be seen in the fact that the stepped piston closest to the device nozzle has a hole lying in the injection axis and connecting the melt chamber with the bore of the device nozzle.

One embodiment of the invention further consists in the step pistons being dependent on the respective chambers prevailing melt pressure are controllable. An advantageous embodiment of the invention can also be seen in the fact that the device nozzle corresponds in terms of its shape, arrangement and dimensions of the spray nozzle to the injection unit of the injection molding machine. It is therefore possible, for example, to use existing two-component injection molding machines and simple injection molding tools without expensive conversions for two-component sandwich injection molding. Because, according to a further embodiment of the invention, the melt-carrying parts, the step pistons and the melt cylinder are designed to be interchangeable independently of the adapter plate remaining in the injection molding machine, an easy adaptation to changed parameters of the method and the injection molded parts is possible. Furthermore, an embodiment of the invention is to be seen in the fact that the device nozzle is releasably connected to the melt cylinder. Therefore, the melt-carrying parts of the device are easily accessible, preferably after unscrewing the device nozzle, and can be replaced in a simple manner. Accessibility from the left is made possible after removing the tool half on the nozzle side.

On the other hand, it is also possible to largely replace the device from the right, without removing the adapter plate from the injection molding machine. Furthermore, an embodiment of the invention consists in that heating devices are arranged in the region of the melt cylinder and the melt channels.

With the help of the heating devices of the melt cylinder, the temperature in the melt channels and the melt chambers is brought to an entered target temperature, at which a perfect axial movement of the stepped piston is guaranteed, without a melt flow taking place over the fit of the stepped piston and the melt cylinder. Finally, an advantageous embodiment of the invention can be seen in the fact that there is a device for automatic, spring-actuated movement of the adapter plate with the device from the fixed tool half, which disengages the device nozzle from the tool sprue bushing brings.

This results in the spatial separation of the hot and cold parts of the device and heat flow into the tool to be cooled is avoided.

Brief description of the drawings

1: detail of an injection molding machine with injection mold and adapter plate with device, in section,

Fig. 2: Detail of the device according to Fig.l, in a schematic sectional view.

Best way to carry out the invention

The adapter plate 1 shown in FIG. 1 consists of a 100 to 120 mm thick steel plate which is screwed onto the tool holder plate 2 on the spray nozzle side together with the tool half 3 on the spray nozzle side. The adapter plate 1 contains the device in which the two melt flows

4; 15 are merged. In principle, it is of course also possible to provide a device for merging more than two melt streams according to the same principle. The melt flow 15 passes through the melt channel 17 into the melt chamber 7, which through the step coils 8; 12 of the valve piston 25 is limited.

When the melt flow 15 is injected into the tool cavity 11, a melt pressure builds up, which acts on the annular surface 9 of the stepped piston 8 and thereby moves it to the right.

This clears the coaxial bore 10 shown in FIG. 2 in the stepped piston 12 and the melt stream 15 flows into the tool cavity 11. The bore 10 has rounded inlet edges at the inlet and outlet of the melt stream 15 and is tapered at the outlet. Flow disturbances can thereby be largely avoided. At the same time, the injection pressure acts on the flow nisch optimized end face 13 of the stepped piston 12 and pushes it to the left.

The melt chamber 14 is thus sealed against the melt flow 4, as can be seen from FIG. 2. If the melt stream 4 is injected, a pressure also builds up in the melt chamber 14. If this is higher than the melt pressure of the melt flow 15, for example twice as high with a corresponding end face area ratio on the stepped piston 12, which acts on the right end face 13 of the stepped piston 12, the stepped piston 12 moves to the right and the melt flow 4 also flows into the tool cavity 11. With the pressure control of the stepped piston 8; 12 of the valve piston 25 in the melt cylinder 24, the melt flows 4; 15 inject one after the other or simultaneously.

When the melt flows 4; 15, immediately before the bore 27 in the device nozzle 20, disturbances in the laminar melt profiles must be largely avoided so that no mixing of the melt streams 4; 15 can be done. This is achieved through rounded edges and widening holes.

The device also acts as a spring-operated shut-off nozzle in that the step piston 8; 12 trained valve piston 25 opens only against the biasing force of the spring 19. The step piston 8; 12 together with the springs 19 and / or with the hydraulic drives, not shown in the drawing, form a "melt pressure compensator". Depending on the on the respective end faces of the stepped piston 8; 12 attacking forces there is a static balance of forces, which the stepped piston 8; 12 holds in a respective position. 1 and 2 each show the rest position. The pressure in the melt chamber 14 is applied to the left annular end face of the stepped piston 12. On the right-hand side, the force of the springs 19 or the force of the hydraulic drives (not shown) or both act together via the stepped piston 8. With a correspondingly graduated dimensioning of the end faces of the stepped piston 8; 12 can act on the annular surface of the pressure of the melt chamber 7. If the equilibrium of forces is changed, for example by the pressure building up in the melt chamber 14, the plug piston 12 moves to the right until the static equilibrium has been restored.

If the stepped piston 12 moves to the right, the pressure of the melt flow 4 is additionally applied to its left end face. Accordingly, due to the larger area, with the melt pressure remaining the same, the force directed to the right increases. The movement to the right is therefore advantageously “self-reinforcing”. The same applies to the stepped piston 8.

After initiating its movement to the right, the additional left end face is acted upon by the pressure of the melt flow 15 in the melt chamber 7, which "reinforces" this movement. The closing movements of the stepped piston 8; 12 to the left are limited by mechanical stops on the device nozzle 20 and on the right-hand end face of the stepped piston 12, which at the same time have sealing functions. Because the force of the springs 19 and the hydraulic drives (not shown) acting from the right keep the bore 10 in the stepped piston 12 and the bore 27 of the device nozzle 20 under prestress, wear-related leakages of the melt streams 4; 15 can be avoided. Another advantage can be derived from the axial movement of the stepped piston 8; 12 derive from the simple monitoring possibility of the device. If the stepped piston 8 moves to the right, the path into the tool cavity 11 is opened to the melt flow 15. When the stepped piston 12 moves to the right, the path for the melt flow 4 opens. This can be done both individually and together. Do the step pistons 8; 12 to the left, the melt streams 4; 15 locked. By the movements of the stepped piston 8; 12 are detected via displacement sensors (not shown), signals are detected which determine the respective state of the device and, for example, visualize it via a control (also not shown). If the device nozzle 20 is first used for the melt flow 4 and then shut off for the melt flow 15 and the tool opened for ejecting the molding, a compression spring assembly 23 presses the device nozzle 20 of the device from the tool sprue bushing 21. In the vast majority of cases, this means that the hot and cold phases are separated at the same time because, for example, tools for sandwich injection molding generally do not have a hot runner. This pressing of the device also enables intermediate spraying outside. The melt emerging from the device nozzle 20 can flow out through the gap 22. After the tool has been closed, the non-positive connection between the device nozzle 20 and the tool sprue bushing 21 is restored by starting the device nozzle 20 for the melt flow 15. Since the device nozzle 20 with the bore 27 corresponds in terms of its shape, arrangement and dimensions of the spray nozzle to the injection unit of the injection molding machine, which in turn corresponds to the tool sprue bushings 21 of the tools used, the device can be used in conjunction with the usual tools. For example, existing two-component injection molding machines and simple injection molding tools can advantageously be combined and used for the two-component sandwich injection molding without complex conversions. The melt channels 6; 17 and the melt cylinder 24 are heated by means of two heating devices 28. The connection for the heating current of the heating device 28 and for temperature sensors (not shown) is expediently made via a multipole plug. The two hot runner control loops can either be controlled via a separate control device or via the machine control.

Industrial applicability

The device according to the invention is used in an injection mold of an injection molding machine for the production of injection molded parts consisting of several plastic components. Existing multi-component injection molding machines can can be operated with the invention with conventional injection molds.

Adapter plate for an injection mold of an injection molding machine

LIST OF REFERENCE NUMBERS

Adapter plate spray nozzle-side tool carrier plate spray nozzle-side tool half

melt stream

sprue bushing

Melt channel (for melt flow 4)

Melt chamber (for melt flow 4)

stepped piston

Ring surface (of the stepped piston 8) bore (in the stepped piston 12) tool cavity of the stepped piston

End face (of the stepped piston 12) Climelzekammer (for melt flow 15) melt flow sprue bushing melt channel (for melt flow 15)

feather

Device nozzle Tool sprue bushing gap Pressure springs

melt cylinder

plunger

Injection axis

drilling

heater

Claims

Adapter plate for an injection mold of an injection molding machine

1.Adapter plate for an injection molding machine for the production of injection moldings consisting of several plastic components, with a fixed and a movable tool carrier plate and a mold consisting of two tool halves, which is arranged between the fixed tool carrier plate and the one tool half and is detachably connected to the latter, and in which a device for melt pressure-dependent control and merging of the plastic components provided by plasticizing units is arranged, characterized in that ß

- The device consists of a melt cylinder (24) lying in the injection axis (26), into which melt channels (6; 17) open, and - A valve piston (25) slidably arranged in the melt cylinder (24) and

- A device for automatically moving the device from the fixed tool half (3) is available.

2. Adapter plate according to claim 1, characterized in that ß the valve piston (25) from the melt chambers (7; 14) form , the individual step piston (8; 12).

3. Adapter plate according to claim 2, d a d u r c h g e k e n n z e i c h n e t, d a ß a step piston (8; 12) against a device nozzle (20) biasing spring (19) is provided.

4. adapter plate according to claim 2, d a d u r c h g e k e n n z e i c h n e t, that the step piston (8; 12) against the device nozzle (20) biasing hydraulic drives are provided.

5. adapter plate according to claim 4, d a d u r c h g e k e n n z e i c h n e t, d a ß the hydraulic drives for the stepped piston (8; 12) are designed to be controllable independently of the melt pressure building up in the melt chambers (7; 14).

6. Adapter plate according to claim 5, d a d u r c h g e k e n n z e i c h n e t, that the hydraulic drives are designed to be controllable by the control of the injection molding machine.

7. adapter plate according to claims 3 and 4, d a d u r c h g e k e n n z e i c h n e t, d a ß the control piston (8; 12) by the spring (19) and the hydraulic drives are designed to be acted upon in combination.

8. Adapter plate according to claim 3, d a d u r c h g e k e n n z e i c h n e t, that the prestressed step pistons (8; 12) the melt chambers (7; 14) are designed to seal against a bore (27) of the device nozzle (20).

Adapter plate according to one of claims 1 to 8, characterized in that the melt chambers (7; 14) individually or together with the Bore (27) of the device nozzle (20) are designed to be connectable.

10. An adapter plate according to claim 9, characterized in that the step piston (12) closest to the device nozzle (20) has a bore (27) in the injection axis (26) that connects the melt chamber (7) with the bore (27) of the device nozzle (20). 10) has.

11. Adapter plate according to one of claims 1 to 10, d a d u r c h g e k e n n z e i c h n e t, that the step pistons (8; 12) are designed to be controllable depending on the melt pressure in the melt chambers (7; 14).

12. Adapter plate according to one of claims 3 to 11, d a d u r c h g e k e n n e e c h e d, that the device nozzle (20) with its bore (27) corresponds in shape, arrangement and dimensions of the spray nozzle to the injection unit of the injection molding machine.

13. Adapter plate according to one of claims 1 to 12, d a d u r c h g e k e n n z e i c h n e t, d a ß the stepped piston (8; 12) and the melt cylinder (24), regardless of the adapter plate (1), are designed to be interchangeable.

14. Adapter plate according to claim 13, d a d u r c h g e k e n n z e i c h n e t, that the device nozzle (20) with the melt cylinder (24) is releasably connected.

15. Adapter plate according to claim 14, d a d u r c h g e k e n n z e i c h n e t, that a ß the device nozzle (20) is designed to be screwed.

16. Adapter plate according to one of claims 1 to 15, characterized in that ß a heating device (28) is arranged in the area of the melt cylinder (24) and the melt channels (6; 17).

17. Adapter plate according to claim 1, d a d u r c h g e k e n n z e i c h n e t, d a ß the device for automatically moving the device from the fixed tool half (3) consists of a device nozzle (20) out of engagement with the tool sprue bushing (21) bringing pressure spring package (23).