EP1007318A1

EP1007318A1 - Method for injection moulding, injection mould, injection moulding device and method for filling a main extruder from a secondary extruder

Info

Publication number: EP1007318A1
Application number: EP98951185A
Authority: EP
Inventors: Heiner Becker
Original assignee: Structoform Spritzgiessen Anisotroper Strukturkomponenten GmbH
Current assignee: Structoform Spritzgiessen Anisotroper Strukturkomponenten GmbH
Priority date: 1997-08-21
Filing date: 1998-08-21
Publication date: 2000-06-14
Also published as: WO1999010158A1; EP1005408B1; WO1999010157A1; EP1005408A1

Abstract

The invention relates to a method wherein a first plastified material is injected into the cavity of an injection mould whereafter another plastified material is also injected into said cavity. The inventive method is characterised in that the first plastified material is fed into the cavity in such a way that it wets only one partial area of the cavity wall and the other plastified material is subsequently fed into the cavity so that it wets at least one part of the remaining area of the cavity wall. Said method enables injected moulded parts to be manufactured using various materials and by means of simple injection devices.

Description

Process for injection molding, injection mold and injection molding device and process for filling a main extruder from a secondary extruder

The invention relates to a method for injection molding injection-molded parts made of plasticizable material, in which a first plasticized material is injected into the cavity of an injection mold and then another plasticized material is injected into the cavity, an injection mold and an injection molding device with a plasticizing unit and an injection unit.

Generic methods are known under the terms "mono-sandwich method" and "two-component method".

In the mono-sandwich process, for example, a particularly pure plasticized material is first injected into an injection mold, which solidifies on the wall of the injection mold and then a filling material is injected, which forms the core of the injection molded part and generally has lower-quality materials. This makes it possible to produce injection molded parts with low material costs, in particular using recycled material, the surfaces of which consist entirely of high-quality material.

In order to produce injection molded parts with elements made of different materials, the two-component process is used, in which different injection units introduce plasticizable materials into the injection mold at different points, so that, for example, a toothbrush with areas made of hard plastic and an articulated intermediate area made of softer material Plastic can be made. However, the two-component process requires a very complex injection molding device and is therefore a relatively expensive production process.

In view of the prior art, the object of the invention is to propose a simple method for the injection molding of injection molded parts made of different materials.

This object is achieved with a generic method in which the first plasticized material is added to the cavity in such a way that it only wets a part of the wall of the cavity and the other plasticized material is then added to the cavity so that at least part of the Remaining area of the wall of the cavity wetted.

In the method according to the invention, a part of the cavity is first kept inaccessible, or so little first plasticizable material is injected that only a part of the cavity wall is wetted. Then at least one further material is placed in the then released remaining cavity, which solidifies in the remaining area of the wall of the cavity, so that the finished injection molded part has an outer surface made of different materials.

The method enables the use of a modified conventional mono-sandwich injection molding machine, whereby contrary to the previously known methods, care is taken to ensure that the second material is not completely covered by the first material. In particular if a high-quality material is also used as the second material, injection-molded parts can be produced from different materials with the method according to the invention indistinguishable from conventional two-component injection molded parts.

A preferred variant provides that the first plasticized material and at least one other plasticized material are injected into the cavity through the same opening. A single opening in the injection mold for different materials leads to inexpensive manufacturing costs for the injection molding device and allows simple process control, since the individual materials are injected into the injection mold in succession at the same place. Accurate dosing and filling times allow excellent work results to be achieved with a wide variety of injection molded parts.

Since the transition area of the injection molded part between the partial area and the remaining area of the wall often forms an odd or blurred line in practice, it is proposed that so much first material be added to the injection mold that after the other material has been injected, the first material up to a shoulder extends in the cavity between the partial area and the remaining area. The shoulder can be any edge that preferably leads from the wall to the cavity interior and forms a barrier for the further flow of the first plasticized material in the area of the shoulder.

As an alternative or in addition to the described method, after the first material has been injected, a slide which releases at least part of the remaining area can be moved. Slide means either a valve-like part that releases a channel to a partial area of the cavity of the injection mold. This makes it possible to direct the flow of the plasticized material via different channels into different partial areas of the cavity from an injection point. The slider can, however also be designed in the manner of a plunger, which is pushed into a partial area of the cavity of the injection mold and covers a partial area of the wall of the cavity. When the slide is pulled back, at least a part of the remaining area of the wall of the cavity is exposed, so that the other plasticized material in this area wets the wall of the cavity.

In addition to the use of various plasticizable materials, hollow injection molded parts can also be produced if a gas space is formed in the injection mold during the injection molding process. Such a gas space is achieved by blowing in a gas during the injection molding process. Cavities can also be formed in such a way that a quantity of material is stretched into an empty space in the cavity (injection blow molding). In this way, two-component injection-molded parts can be produced in a cost-effective manner that have a cavity. The cavity can be left under gas pressure.

A large number of particularly advantageous applications open up when a plasticized material is a relatively soft or rubber-like material and at least one other plasticized material is a relatively hard material. While the soft or rubber-like material takes on the function of a seal, a tire or a handle, the relatively hard material serves to produce a solid base body.

Special effects are also achieved in that the plasticizable materials have at least two different colors or transparencies. While the different colors serve optical effects, it is also possible to produce injection molded parts with colored and transparent areas, for example as a cover with a transparent window can be used. In particular, transparent injection molded parts, which are colored in partial areas to prevent a view through, can be produced particularly inexpensively using the described method.

It is also advantageous for various applications if at least one plasticized material has gas inclusions. Gas inclusions reduce weight and material costs and, depending on the application, can have other specific advantages.

For recycling recycling particles, for example, it is proposed that at least one plasticized material have inclusions of another component. For example, elastomers can be used in a soft material

Recycled particles can be mixed in to adjust the hardness of the material.

The method described above can also be used to combine biodegradable material with other materials, in particular with other biodegradable materials. On the one hand, a material mixture can take place, on the other hand, the different materials can also be injected as the first and second material. This combination opens up completely new possibilities, since the biodegradable material can be surrounded by a protective layer, for example. In particular, the protective layer can only be selected to be resistant over a period of time or under certain conditions. For example, a water-decomposable material can be surrounded by a layer that can be degraded by microorganisms or by UV light. This creates a water-resistant part, which, after the outer layer has been broken down, can be quickly decomposed. It goes without saying that the combination of a biodegradable material is itself advantageous. An injection mold which has at least one sensor which is arranged at the transition between the partial region and the residual region of the wall of the cavity of the injection mold is particularly suitable for carrying out the method according to the invention. These sensors allow, for example, pressure, temperature or ultrasound measuring devices to determine when a certain plasticized material has reached the location of the wall in which the sensor is attached. This allows the injection process to be closely monitored and controlled.

In particular, it is possible to arrange such a sensor in an ejector hole in the tool. For example, this can be an ultrasonic sensor that is used for quality assurance. By using an ejector hole, the sensor can be attached without further effort, since the provision of suitable ejector holes has to be carried out anyway and only a further, corresponding hole needs to be provided. An existing hole can also be used, particularly in the case of existing shapes.

It goes without saying that this can be any type of bore in the ejector block as long as it extends to the workpiece. The hole can be closed on the tool side, but it is still possible to bring a sensor extremely close to the workpiece using this hole.

It is advantageous if an injection mold which can be used above all for the method according to the invention has a shoulder which is arranged at the transition between the partial region and the remaining region of the wall of the cavity of the injection mold. As stated above, this paragraph allows a straight transition line between the components. In spitless spraying, a two-component mixture remains in the hot runner of the injection mold, which mixture can get into the cavity of the injection mold when another part is sprayed. However, this would lead to contamination of the outer layer of the next injection molded part. It is therefore proposed that the injection mold have a hot runner with a diverter which allows plasticized material flowing to the cavity to flow into an overflow. After the first injection molding process, the bypass device first deflects downstream material into the overflow until pure material reaches the channel. This makes it possible to collect the dirt in the overflow and then dispose of it. The material collected in the overflow can also be used further, for example in order to subsequently seal a gas hole in the vicinity of the overflow. This can be done for example by means of a stamp which conveys melt from the overflow.

An injection molding device with a plasticizing unit and an injection unit is also proposed, which has at least two secondary extruders, which are arranged between the screw tip and the nozzle tip. The use of several secondary extruders allows different materials to be added to the injection mold one after the other in order to use the process according to the invention to produce injection molded parts from a wide variety of materials.

An injection molding device with at least one injection unit, which comprises an injection piston, which can inject melt from a melt chamber, and with at least two extruders connected to this melt chamber is also proposed. Such an arrangement makes it possible to inject extremely small workpieces and also use very sensitive melts for this purpose. In particular, it is also possible to use the fifo (first in, first out) principle To load the melt chamber with two different types of melt and in this way to produce precision components from different materials or to carry out micro-injection molding with two different materials.

An injection molding device with a main extruder, which has a melt space from which a nozzle extends via a hot runner, and with a secondary extruder can be operated particularly simply in such a way that melt from the secondary extruder is transferred out of the melt space when the melt space enters via a switching device second channel can be connected, which is connected to the secondary extruder, the switching device being coupled to the movement of the secondary extruder.

Such a coupling can be ensured, for example, simply by a rigid connection between the switching device and the secondary extruder. On the other hand, spring elements can be provided. In addition, it is also conceivable to actively operate the switching device and to control it, for example by means of pneumatics or hydraulics, as a function of the movement of the plasticizing device.

The switching device can comprise an adjusting nozzle which bears on a surface, preferably on a surface of the secondary extruder, and is fastened with a flange. Such an adjustment nozzle also ensures an extremely simple construction and an extremely simple replacement of the adjustment nozzle, regardless of the other features of the injection molding device.

In this respect, it does not matter to what extent hot channels or only supply channels are arranged in this nozzle. In addition, the hot runner can have a pressure-dependent valve. With such an arrangement, passage control of the hot runner via the movement of the secondary extruder can be dispensed with. The passage is then regulated depending on the pressure. At low pressures, at which melt is transferred from the secondary extruder to the main extruder, such a pressure valve does not yet respond. It only switches at pressures that are applied by the main extruder during the spraying process. In this way, the spraying process can be further simplified. Such a pressure-dependent valve can also be used advantageously independently of the other features of the injection molding device.

The switching device, on the other hand, can have two subchannels that open or close the hot runner or the feed channel depending on the position of the switching device. This enables simple control of the switching device depending on the movement of the secondary extruder.

In particular, it is possible to design one of the subchannels in such a way that it closes the second channel from the secondary extruder to the main extruder when the secondary extruder has reached its transport position in which it can convey melt into the main extruder.

The switching device can have a subchannel block in which the subchannels are arranged and which is guided in a block guide. This ensures reliable switching. For example, the adjustment nozzle described above can be used as the subchannel block. However, other devices, such as plates, with the subchannels are also conceivable as a subchannel block. The subchannel block can be used as described above connected to the secondary extruder or controlled independently of it.

A particularly simple construction can be ensured if the hot runner is arranged in the block guide. Then the subchannel block can be shifted in such a way that on the one hand a subchannel opens the hot runner and on the other hand the other subchannel - if the subchannel block is arranged in the appropriate position - opens the path between the secondary extruder and the hot runner or main extruder.

In addition, an injection molding device with a movable between an injection position and a rest position along a path

Main extruder and proposed with at least one secondary extruder, which comprises a switching device between the injection position and the

Rest position is arranged which is a channel with an input and a

Has output and which is pivotable between a loading position and a release position, with the input on the

Auxiliary extruder and the exit points to the main extruder and being in the

Release position the way for the main extruder is free. If the input is rigidly connected to the secondary extruder, the above-described movement coupling between the switching device and secondary extruder follows immediately. However, other couplings are also conceivable.

Such a pivotable switching device allows the above-described methods and also other methods in their

Accelerate or simplify the process considerably, regardless of the movement coupling with the secondary extruder. It is no longer necessary to use the secondary extruder or extruders with the main extruder to move with. Rather, the secondary extruder and the switching device are suitably controlled depending on the respective time of the process. If the main extruder is in its rest position, the switching device is brought into its loading position, and the secondary extruder and the main extruder are each applied to the input or output of the switching device. Then the main extruder can be loaded through the secondary extruder. After loading, the secondary extruder is removed from the entrance and the switching device is pivoted away, so that the path for the main extruder is clear.

The arrangement described above is very small if the input and the output of the switching device form an acute angle to one another. With such an arrangement, the switching device can be arranged directly in front of a nozzle plate of the injection molding device, since no additional space is required at this point for the secondary extruder and this protrudes approximately V-like from the main extruder. In this way, the distance to be traveled by the main extruder can be minimized, so that the overall time for the injection molding process is reduced.

It goes without saying that such a V-shaped arrangement of the main and secondary extruders is advantageous in itself in order to reduce the installation space required and thus the distance to be traveled by the main extruder.

In addition, an injection molding device is provided with a main extruder which can be moved along a path between an injection position and a rest position, which in its injection position with a nozzle passes through a nozzle plate and at least part of an adapter plate through an injection opening, and with a secondary extruder which is between a loading position and a Release position is shiftable, proposed, in the release position the path of the injection device is free and in the loading position an outlet of the secondary extruder points to the nozzle of the main extruder and this outlet is arranged in an opening of the adapter plate which opens into the injection opening. The adapter plate opening can on the one hand open into the spray opening at an angle of 90 ° and on the other hand at an acute angle.

It is also conceivable to provide the opening for the secondary extruder in the nozzle plate. This is particularly advantageous when there is no adapter plate. For this purpose, the outlet of the secondary extruder is arranged in the loading position in an opening in the die plate which points into the injection opening.

As a result of the measure described above, the position in which the main extruder has to be if it is to be filled with a melt by the secondary extruder can be shifted extremely close to the tool into the tool space. In this way, the distance to be covered by the main extruder is minimized when driving back to release the exit, so that the total time for the injection process is reduced.

The auxiliary extruder can be supported on the output side, at least in its filling position, against a force exerted by the main extruder. This can be done by a guide in the adapter plate or a nose engaging in the adapter plate. In this way, a correct fit of the main extruder at the outlet of the secondary extruder can be ensured while the main extruder is being filled from the secondary extruder. In addition, the secondary extruder does not need to be designed to be exceptionally stable, since the support described above ensures sufficient stability. It is with this arrangement in particular, it is also possible to use known auxiliary extruders and to provide them with a corresponding extension piece, so that this embodiment can be implemented at relatively low cost.

Ultimately, the invention proposes a method for filling a main extruder of an injection molding device with a melt from a secondary extruder, the melt being filled into the main extruder through a feed channel into a hot runner which is connected on the one hand to the main extruder and on the other hand to a tool the injection process is controlled in such a way that a sprue of a solidified or solidifying workpiece is left in the hot runner between the tool and the point at which the feed channel opens into the hot runner until the main extruder is filled with the melt.

In this way it can be ensured that the melt from the secondary extruder does not inadvertently flow towards the workpiece, but instead reaches the main extruder. As soon as the main extruder is filled accordingly, the workpiece can be ejected.

A valve in the hot runner can be dispensed with by the prescribed method.

The sprue advantageously extends directly to the point at which the feed channel opens into the hot runner.

The method according to the invention and a wide variety of exemplary embodiments for using the method according to the invention are shown in the drawing and are explained in more detail below. It shows, FIG. 1 schematically, a three-dimensional view of an injection molding device according to the invention with a tool,

FIG. 2 shows a detail from FIG. 1 as a sectional view,

FIG. 3 shows a section through an alternative embodiment of an injection molding device in a schematic illustration,

FIG. 4 shows a section through a cover component,

FIG. 5 shows an enlarged detail from FIG. 4,

FIG. 6 shows a section through a further cover component,

FIG. 7 shows a section through a roller component,

FIG. 8 shows a section through a section of the roller component according to FIG. 7 in an embodiment with a profile,

9 shows a section through a section of the roller component according to FIG

7 with positive tire connection,

FIG. 10 shows a section through a section of the roller component according to FIG. 7 with a gas-filled tire part,

FIG. 11 shows a section through a section of a roller component according to FIG. 7 with the tire part molded on from the hub, FIG. 12 shows a section through a roller component with a ball roller,

FIG. 13 shows a section through a handle,

FIG. 14 shows a view of a brush handle,

FIG. 15 shows a section through a housing with a seal in the housing shown schematically in the upper part and a seal in the cover part and cable passage shown schematically in the lower part,

FIG. 16 shows a section through a screwed cable gland,

FIG. 17 shows a view of a first embodiment of a bottle stopper,

Figure 18 shows a section through another embodiment of a

Bottle stopper,

FIG. 19 shows an injection molding device with a tool,

FIG. 20 shows a detail from FIG. 19 with a hot runner for sprueless spraying,

FIG. 21 shows a further injection molding device in a schematic illustration,

FIG. 22 shows a perspective view of a hot runner block with an adjusting nozzle as the switching device, FIG. 23 shows a section through the adjustment nozzle according to FIG. 4,

FIG. 24 shows a schematic section through a further switching device,

FIG. 25 shows a schematic illustration of a tilting nozzle and serving as a switching device

Figure 26 shows another injection molding device in schematic representation.

The injection molding device 1 shown in FIG. 1 has a nozzle 2 which is connected to a tool 3. On the other side of the nozzle there are two secondary extruders 4 and 5, which are placed on the main extruder 6. The two secondary extruders have feed hoppers 7 and 8 and the main extruder has a feed hopper 9.

The tool 3 has a first inlet 10 for plasticized components and a second inlet 11 for a gas to form a cavity in the injection molded part. In addition, a slide 12 is provided in the tool 3. This slide 12 ensures that initially only a portion of the wall of the cavity of the tool cavity with plasticized! Material is wetted and a residual area of the wall of the cavity is wetted with plasticized material only after pulling the slide 12. The cavity of the tool is thus divided into a partial area and a remaining area, the remaining area being released only after the slide 12 has been pulled.

The part of the injection molding device 1 adjoining the nozzle 2 is shown as a detail in FIG. The nozzle 2 is first connected to a partial area with a first plasticized material 13, which passes through the filling funnel 7 and the Auxiliary extruder 4 is fed. This is followed by a further area, which is fed via the hopper 8 and the secondary extruder 5 with a second plasticized material 14. The remaining area of the injection molding device 1 is filled with a third plasticized material 15, which is fed via the hopper 9 and is conveyed in the main extruder 6 by means of a screw 16.

This allows different plasticized materials 13, 14, 15 to be filled into the tool 3 via the nozzle 2 in succession. Preferably, when changing from one material to another, the slide 12 is pulled in order to wet a remaining area of the wall of the cavity of the tool with another plasticized material.

Another injection molding device according to the invention is shown in FIG. 3. Here, extruders 21, 22 and 23, 24 are arranged on two sides of a tool. The extruders 21 and 22 convey plasticizable material to a channel 25, which leads to an opening 26 in the tool 20, and the extruders 23 and 24 convey plasticized material to a channel 27, which leads to an opening 28 in the tool 20.

To operate the device, either plasticized material can first be conveyed with the extruder 21 to the cavity 29 of the tool 20, after which another plasticized material is then conveyed into the cavity 29 with the extruder 22. As an alternative to this, plasticized material can also first be pushed into the extruder 22 with the extruder 21, after which the plasticized material originating from the extruder 21 is first conveyed into the cavity 29 with the extruder 22 and then plasticized material provided with the extruder 22 is subsequently conveyed. The same process variants are of course also possible with the extruders 23 and 24 possible, the implementation of the method according to the invention also being possible with the extruders 21 and 22 alone.

The channel 30 optionally connects the extruders 23 and 24 to the extruders 21 and 22 with the interposition of a pump 31 and thus allows four different plasticized materials to be introduced one after the other into the cavity 29 of the tool 20 at the opening 26 or at the opening 28. The corresponding necessary sliders are not shown to increase clarity. However, a person skilled in the art will readily recognize that with the device according to FIG. 3, up to four different materials can be filled into the cavity 29 through an opening 26 or 28 and that the device allows a wide variety of process procedures by means of built-in slides.

For example, it is possible to use a device according to FIG. 1 or 3 to produce the cover component 40 shown in FIG. For this purpose, a harder material 42 is first injected into an injection mold at the sprue 41, which solidifies on the walls of the mold. Subsequently, a slide is pulled, which opens an opening in the areas 43, 44, so that softer material 45 conveyed on the sprue 41 flows in the cavity of the tool into the space released by the slide, in order to form a protruding seal 46.

The cover 40 thus has a sheath made of harder material 42 under which there is a softer material 45 which is only visible as a ring 46 in the edge region of the cover 40.

The sprue area shown enlarged in FIG. 5 shows the harder plasticized material 42, which solidifies on the walls of the cavity and the softer material 45 conveyed at point 41, which flows into the mold in the central region between the walls of the cavity.

FIG. 6 shows an alternative embodiment for producing a cover by the method according to the invention. The cover component 50 shown there consists of a curved cover part 51, which is first injected from the mold inlet 53 via a channel 52. Subsequently, the slide 54 is changed over so that softer material flowing in from the opening 53 penetrates via the channels 55 and 56 into a sealing area 57 released by a slide in order to form an annular seal 58 which is firmly connected to the curved cover component 51 made of harder material is.

Instead of using a slide or in addition to this, a shoulder 59 (see FIG. 4) can be provided at the transition point between the materials in the mold, which ensures that the first plasticized material only flows up to this shoulder and only the second plasticized Material flows over this paragraph. In FIG. 4, a shoulder 59 of this type, arranged transversely to the direction of flow, is provided, opposite which another shoulder 60 is arranged. As a result, the hard component 42 only flows up to the shoulders 59 and 60 and hardens at the edge of the mold. The flowing material 45 is no longer braked by the shoulders 59 and 60, since the plastic material 52 on the outside has already solidified up to the inner edge of the shoulder, so that the flowing material 45 flows over the shoulder and wets the remaining area of the wall of the cavity .

A roller component 70 with different configurations of a radially outer tire 71 to 75 is shown in FIGS. 7 to 11. In its basic variant, the roller component 70 consists of a hub 76 and a radial one on it subsequent tires 71. The mold intended for injecting this component has an inlet 77 which leads to a channel 78 in order to inject the hub part 76 from a harder material. A slide 79 arranged between the inlet 77 and the channel 78 is then changed over so that softer material flows via the channel 80 into the radially outer region of the hub 76 in order to form a tire 71.

The embodiment variant according to FIG. 8 provides that a profile is formed in the tire 72. According to FIG. 9, the tire 73 is connected to the hub component 76 by means of a positive connection 81. FIG. 10 finally shows the introduction of a gas into the tire part in order to achieve a "balloon effect" by means of an air bubble 82. The last embodiment according to FIG. 11 shows an alternative way of producing the tire by injecting the softer tire component via the channel 78 following the harder component, so that, similar to the cover component according to FIG. 4, the softer component flows in the middle of the hard component and forms a tire 75 radially outside. Here too, it is possible to work either with a slide which releases a remaining area of the cavity or with a heel which hinders the flow of the first component.

A further roller component, which can also be referred to as a ball roller 90, is shown in FIG. 12. Here, a hard component is first injected into the mold via a ring sprue 91 and then a soft component is injected via the sprues 92 and 93. However, like the cover component according to FIG. 4, this component can also be produced with two different materials injected one after the other at the sprue 91. The hardness of the soft component 94 can be adjusted by mixing in elastomer recycling particles. FIG. 13 shows a handle 100 comprising a handle body 101 and a handle shell 102, a gas bubble 103 preferably being provided in the handle body. The handle body is injected from a harder material through the inlet 104 and the handle shell from the foam 105 through the inlet 105. Optionally, soft components can be molded on the inside, for example for door handles or as a lever for a handbrake and for pedals.

FIG. 14 shows a brush handle 110, in which a soft component 111 is first injected over the sprue 112 and then a hard component 114 is injected over the sprue 113. Of course, as in the other exemplary embodiments, the different materials 1 1 1 and 1 14 can additionally or alternatively have different colors or can be plasticizable materials with different properties in other respects. In particular, any type of handles, cutlery, for example for camping with a soft handle, designer cutlery, toothbrushes or tool handles can be produced by this method. By combining it with a gas bubble, it is also possible, for example, to produce two-component, hollow parts, in particular handles or the like.

A further frequent application of the described method is the production of a housing 120 shown in FIG. 15. In the schematic illustration according to FIG. 15, this housing 120 has a seal 121 in the upper part of the drawing and one in one in the lower part of the figure Matching cover part 122 arranged seal 123 which interacts with a correspondingly shaped opposite side 124 in the housing 120. This housing can be produced in accordance with the previously described cover using the method shown in FIGS. 4 and 6. An advantageous one Design of the housing shows a cable passage 125, which has a ring 126 made of a softer plastic material.

A cable gland 130 with claw-shaped strain relief 131 and a seal 132 is shown in FIG. 16. In this embodiment, a harder component 134 is first injected at the tool inlet 133, which forms the body of the cable gland 130 and the claws of the strain relief 131. Subsequently, the slide 135 is flipped so that in addition to the central channel 136, two further channels 137 and 138 are released, so that inflowing softer material can flow into an area released by a slide (not shown) to form the seal 132. At the same time, a partial flow of the softer material flows in the central channel 136 to the strain relief 131 in order to also form a body 139 made of softer material there.

While the claws of the strain relief 131 are shown in the uncompressed state in the upper part of FIG. 16, the lower part of the figure shows how the claws of the strain relief 131 are pressed together by means of a screwed-on gill nut 140.

It goes without saying that a large number of electrical articles or electrical accessory articles can be produced in this way.

FIG. 17 shows a bottle cap 150 as a further exemplary embodiment. This bottle cap consists of a harder component 151, which forms the base body, and a softer component 152, which emerges in a ring-shaped manner and acts as a seal. A gas bubble 153 is provided within the harder component 151 to save material and to allow a higher flexibility of the bottle stopper. The closure can also be solid.

Another bottle cap 160 is shown in FIG. 18. In this bottle cap, a hard inner part 161 is surrounded by a softer material 162, and the type of materials can also be exchanged. The inner part 161 preferably has ribs 165 running from a central axis 163 to an annular body 164.

The method according to the invention can be used for countless other applications, such as wheels made of hard and soft components, children's toys made of differently colored components, joints made of hard and soft components, and lids made of opaque and transparent areas. Other examples include: screwdriver handles, clothes hangers with anti-slip edges, shock absorbers, buffers, silent blocks, furniture fittings, buttons or shoe soles. For example, parts can also be produced, of which at least one material component is non-stick or hydrophobic. This component is then quasi self-cleaning and could be used, for example, for shoe soles, in particular for shoe soles with studs. Other important areas of application are conveyor belts, transport rollers and transport rollers.

Figures 19 and 20 show the use of a tool with a special hot runner. When two different materials 170, 171 are injected into a tool 173 with an injection unit 172, different materials 170, 171 enter the tool 173 one after the other. An outer ring is formed in the hot runner from the first component 170, in which the further component 172 forms the core lies. After the spraying process with the Component 171, however, has to be replenished with new component 170 and usually the rest of the second component 171 remaining in the hot runner 174 is pressed into the cavity as contamination.

In order to avoid such contamination, FIG. 20 shows an overflow 175 and a slide 176 in the hot runner 174. The slide 176 allows the rest of the second component 171 with the replenished first component 170 to be pressed into the overflow 175 and only then the cavity 177 to release when the first material is again on the slide 176. A sprue bar is no longer necessary.

The injection molding device 200 shown in FIG. 21 comprises an injection unit with an injection plunger 201, which can inject melt from a melt chamber 202. Melt from two extruders 203 and 204 can be filled into the melt space 202. The injection piston 201 is driven by an injection cylinder 205. With such an arrangement, particularly fine precision components can be produced. This arrangement is particularly suitable for micro injection molding with two different starting materials.

The connection between the extruders 203 and 204 can be ensured on the one hand via valves. However, it is also possible to ensure that the melt space 202 is filled as desired by suitable selection and control of the melt streams flowing during filling.

A hot runner block 230 shown in FIG. 22 cooperates with a special adjustment nozzle 231. This adjusting nozzle 231 is attached to a secondary extruder 263 by means of a flange. In this way, the adjustment nozzle 231 can be positioned very easily. In particular, the distance of the Not the end of the nozzle when the adjustment nozzle is adjusted, as is the case with screwed-in adjustment nozzles according to the prior art.

The hot runner block 230 has a continuous channel 232 and a central, round opening 233 which intersects the channel 232 and into which the adjusting nozzle 231 can be inserted. This nozzle 231 has a bore 234 extending transversely to the nozzle axis. which corresponds to the diameter of the channel 232 and is aligned with the channel 232 by sinking the adjusting nozzle into the opening 233 of the hot runner block 230.

An L-shaped bore 235 is provided above the bore 234 in the adjustment nozzle 231, which is also to be aligned with the channel 232 and then connects the secondary extruder 236 to the channel 232 in order to plasticize material from the secondary extruder 236 through the L-shaped one Promote channel 235 to channel 232.

Channel 232, on the other hand, communicates with a main extruder 237.

The adjusting nozzle 231 thus serves as a switching device in order to switch a flow path between the main extruder 237 and the secondary extruder 236 or the workpiece. It is understood that such an adjusting nozzle 231 is also advantageous for other switching devices.

In addition, the flanging can also advantageously be used independently of the other features of the adjusting nozzle 231 for any type of nozzle that is to be precisely adjusted. Another switching device 240 is shown in FIG. 24. This includes a hot runner 241, in which melt can be guided from a main extruder to a mold cavity (as indicated by arrow 246). A partial duct 242 branches off from this hot duct 241 and can be connected to a feed duct 243 of a secondary extruder as required. This is done in that a sleeve, which surrounds the hot runner and in which the supply channel 243 is provided. is moved along the hot runner 241. Through this movement, the feed channel 243 can optionally be brought into congruence with the partial channel 242.

A pressure valve is arranged in the hot runner 241 immediately behind the point at which the subchannel 242 branches off, so that no melt reaches the mold cavity during the filling of the main extruder through the secondary extruder. This is dimensioned such that it remains closed at the pressures applied by the secondary extruder, while it opens at the pressures applied by the main extruder.

Instead of the pressure valve 245, the spraying process can also be carried out in such a way that, starting from the mold cavity, a sprue is left in the hot runner 241, which reaches up to this point. This sprue ensures that the melt does not flow towards the mold cavity. Only when the main extruder is filled in the desired manner is the workpiece ejected with this sprue, so that the hot runner 241 is released again.

A further switching device is shown in FIG. 25. A tilting nozzle 250 with an input 251 and an output 252, which are connected by a channel 253, serves as the switching device. The tilt nozzle 250 is about an axis 254 pivotable and attached to a pull rod 256 of the main extruder 257 by means of a mounting bracket 255.

In a loading position (shown in FIG. 25), the inlet 252 points to the spray nozzle of the main extruder 257, while the inlet 251 points to a secondary extruder 258. In this position, the main extruder 257 and the secondary extruder 258 can be brought into contact with the inlet 251 and the outlet 252 and melt can be filled into the main extruder 257.

After the main extruder has been filled in the desired manner, the tilting nozzle 250 is folded up in the direction of the arrow, so that the path for the main extruder 257 is clear and the latter can be moved into its injection position.

In another embodiment, the secondary extruder 258 can be firmly connected to the tilting nozzle 250 and pivoted together with the latter.

As shown in Figs. 24 and 25, the secondary extruder and main extruder are arranged at an acute angle or in a V-shape with respect to one another. This makes it possible to bring the switching device 240 or 250 extremely close to the tool, so that the distances traveled by the main extruder are minimized. This leads to an increase in the speed of the spraying process.

Another possibility of how the working speed can be increased in a spraying device is shown in FIG. 26. Here, a nozzle 301 of a main extruder passes through a nozzle plate 302 and at least part of an adapter plate 303 through a spray opening 304 in order to get into its spray position. Here, the nozzle plate 302 denotes one Main extruder-side termination of the tool space, while the adapter plate 303 is a part arranged on the nozzle plate 302, which is used to adapt to different tools and the like.

An opening 305 is provided in the adapter plate 303, which opens into the spray opening 304. An extension piece 306 extends through the opening 305 and leads from an auxiliary extruder to an outlet 307. By moving the auxiliary extruder, the outlet 307 can be brought into the injection opening 304, so that when the nozzle 301 is in contact with the outlet 307, the main extruder can be filled by the auxiliary extruder.

For reasons of stability, a nose 308 is provided at the end of the outlet 307 pointing away from the secondary extruder, which lug engages in a corresponding recess 309 in the adapter plate 303. For cleaning purposes, the recess 309 can be guided out of the adapter plate 303, so that excess melt can be removed here.

As can be seen immediately, such an arrangement can minimize the distance to be traveled by the nozzle 301 if an adapter plate is provided in the tool space.

Since 306 standard components can be used as an extension piece, this embodiment is also particularly cost-effective. In order to prevent melt from running out, needle shutters can be provided at the outlet 307 and at the nozzle 301.

The above-described arrangements and methods can in particular also be used for pipes with a connecting sleeve, hoses with fastening elements, Brackets or connectors, pipes with flexible spacers or clutch pedals or other pedals including levers and linkages are made with a soft element on the pedal.

All of this can be done in a single spraying process, which considerably reduces the duration of the process.

In practice, switching from a first component to another and possibly to a third, fourth, etc. component requires a great deal of experience, since the timing must be precisely coordinated. In order to record the correct point in time, sensors can be installed in the injection molding device and in particular in the mold or in an ejector bore, which use pressure, temperature or ultrasound to monitor the filling of the cavity with the different plasticized materials. For better process monitoring, a pause can be made between the feeding of different plasticized materials. In addition, the path control of the screw, i.e. the path conveyed by the screw can be used directly to control the slide. Instead of the path, the time from the onset of the injection process can also be measured in order to determine the correct time for the slide control. Ultimately, the cavity pressure can also serve as a parameter for the slide control.

Claims

Claims:

1. A method for injection molding of injection-molded parts made of plasticizable material, in which a first plasticized material is injected into the cavity of an injection mold and then another plasticized material is injected into the cavity, characterized in that the first plasticized material is added to the cavity that it wets only a part of the wall of the cavity and then the other plasticized material is added to the cavity so that it wets at least a part of the rest of the wall of the cavity.

2. The method according to claim 1, characterized in that the first plasticized material and at least one other plasticized material are injected through the same opening in the cavity.

3. The method according to any one of the preceding claims, characterized in that so much first material is added to the injection mold that after the other material has been injected, the first material extends to a step in the cavity between the partial area and the remaining area.

4. The method according to any one of the preceding claims, characterized in that after the injection of the first material at least a part of the remaining area releasing slide is moved.

5. The method according to claim 4, characterized in that the slide releases a channel to a portion of the cavity of the injection mold.

6. The method according to claim 4, characterized in that the slide directly releases a portion of the cavity of the injection mold.

7. The method according to any one of the preceding claims, characterized in that a gas space is formed during the injection molding process in the injection mold.

8. The method according to any one of the preceding claims, characterized in that a plasticized material is a relatively soft or rubbery and at least one other plasticized material is a relatively hard material.

9. The method according to any one of the preceding claims, characterized in that the plasticized materials have at least two different colors or transparency.

10. The method according to any one of the preceding claims, characterized in that at least one plasticized material has gas inclusions.

11. The method according to any one of the preceding claims, characterized in that at least one plasticized material has inclusions of another component.

12. Injection mold, characterized in that it has at least one sensor which is arranged at the transition between the partial area and the remaining area of the wall of the cavity of the injection mold.

13. Injection mold, in particular according to claim 12, characterized in that it has a shoulder which at the transition between the sub-area and

Remaining area of the wall of the cavity of the injection mold is arranged.

14. Injection mold, in particular according to claim 12 or 13, characterized in that it has a hot runner with a diverter which allows plasticized material flowing to the cavity to flow into an overflow.

15. Injection molding device with a plasticizing unit and an injection unit, characterized in that it has at least two secondary extruders which are arranged between the screw tip and the nozzle tip.

16. Injection molding device with at least one injection unit, which comprises an injection piston (201) which can inject melt from a melt space (202), and with at least two extruders (203, 204) connected to this melt space.

17. Injection molding apparatus with a main extruder (237, 257), which has a melt chamber, from which a nozzle emerges via a hot runner (241), and with a secondary extruder (236, 258), characterized in that the melt chamber via a switching device (230, 240) a second channel can be connected, which is connected to the secondary extruder (236, 258) and leads to the melt space, the switching device being coupled to the movement of the secondary extruder.

18. Injection molding device according to claim 17, characterized in that the switching device (230, 240) with the secondary extruder (236) is rigidly connected.

19. Injection molding apparatus according to claim 17 or 18, characterized in that the switching device (230) comprises an adjusting nozzle which bears on a surface, preferably an auxiliary extruder, and is fastened with a flange.

20. Injection molding device according to one of claims 17 to 19, characterized in that the hot runner (241) has a pressure-dependent valve (245).

21. Injection molding device according to one of claims 17 to 20, characterized in that the switching device (230, 240) has two sub-channels

(234, 235; 241, 242, 243), depending on the position of the

Switching device the hot runner or a feed channel from the

Open or close the secondary extruder.

22. Injection molding device according to claim 21, characterized in that the switching device (230) has a partial channel block (231) in which the Sub-channels (234, 235) are arranged and which is guided in a block guide (233).

23. Injection molding device with a main extruder (257) which can be moved along a path between an injection position and a rest position and with a secondary extruder (258), characterized by a switching device (250) which is arranged between the injection position and the rest position and which has a channel (253 ) with an input (251) and an output (252) and which is pivotable between a loading position and a release position, wherein in the

Loading position of the inlet (251) on the secondary extruder (258) and the outlet (252) on the main extruder (257) and the path for the main extruder (257) is free in the release position.

24. Injection molding device according to claim 23, characterized in that the inlet (251) and the outlet (252) form an acute angle to one another.

25. Injection molding apparatus having a main extruder which can be moved along a path between an injection position and a rest position and which, in its injection position, passes through a nozzle plate (302) and at least part of an adapter plate (303) through an injection opening (304), and with a secondary extruder that can be moved between a loading position and a release position, the path of the main extruder being free in the release position and in the

Loading position an outlet (307) of the secondary extruder points to the nozzle (301) of the main extruder, characterized in that the outlet (307) is arranged in an opening (305) of the adapter plate (303) which opens into the spray opening (304).

26. Injection molding apparatus according to claim 25, characterized in that the auxiliary extruder is supported on the output side at least in its filling position against a force exerted by the main extruder.

27. A method for filling a main extruder of an injection molding device with a melt from a secondary extruder, the melt being passed through a feed channel into a hot runner, on the one hand with the

Main extruder is connected and on the other hand leads to a tool, is filled into the main extruder and the injection process is controlled in such a way that a sprue of a solidified or solidifying workpiece is left in the hot runner between the tool and the point at which the feed channel opens into the hot runner until the main extruder is filled with the melt.