DE19808145A1 - Injection moulding of articles with two components - Google Patents

Abstract

A first material is injected into the mould so that it only wets part of the mould cavity wall. Subsequently another material is injected to wet the rest of the mould wall. Independent claims are also included for the following: (a) an injection moulding mould with a sensor fitted at the transition between the two sections of mould wall; and (b) an injection moulding installation with two side extruders (4,5) between the main extruder screw tip and the nozzle (2).

Description

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

Generic processes are under the term "mono-sandwich process" and "two-component process" known.

In the mono-sandwich process, an injection mold is first placed in a mold particularly pure plasticized material injected, which is on the wall the injection mold solidified and then a filling material injection molded, which forms the core of the injection molded part and in general inferior materials. This makes it possible with low Material costs, especially using recycled materials Manufacture injection molded parts whose surfaces are made entirely of high quality Material.

To manufacture injection molded parts with elements made of different materials, the two-component process is used, in which different Injection units plasticizable materials in different places in the Introduce the injection mold so that, for example, a toothbrush with areas  hard plastic and an articulated intermediate area made of softer Plastic can be made. The two-component process is required however, a very expensive injection molding device and is therefore a relative expensive manufacturing process.

The invention lies in the light of the prior art Task based on a simple method for injection molding of injection molded parts to propose from different materials.

This object is achieved with a generic method in which the first plasticized material is placed in the cavity so that there is only one Part of the wall of the cavity wetted and then the other plasticized material is placed in cavity so that there is at least part the remaining area of the wall of the cavity is wetted.

In the method according to the invention, part of the cavity first becomes kept inaccessible or there is so little first plasticizable material injected that only part of the cavity wall is wetted. Subsequently at least one other material is placed in the cavity, which in the Remaining area of the wall of the cavity solidifies, so that the finished Injection molded part has an outer surface made of different materials.

The method allows the use of a slightly modified one conventional mono-sandwich injection molding machine, being contrary to the previous known method, care is taken to ensure that the second material is not is completely covered by the first material. Especially when second  A high quality material can also be used with the material Process according to the invention injection molded parts made of different materials are manufactured by conventional, two-component processes manufactured injection molded parts are indistinguishable.

A preferred variant provides that the first plasticized material and at least one other plasticized material through the same opening in the Cavity is injected. A single opening in the injection mold for different materials leads to cheap manufacturing costs for the Injection molding device and allows a simple procedure because the individual materials one after the other in the same place in the injection mold be injected. Accurate dosing and cycle times help different injection molded parts for excellent work results.

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

Alternatively or in addition to the described method, the Injecting the first material into at least part of the remaining area releasing slide are moved. Under slider is either a  understood valve-like part that a channel to a portion of the Releases cavity of the injection mold. This allows one injection point the flow of plasticized material in different channels to direct different sections of the cavity. The slider can, however also be designed in the manner of a plunger, which in a partial area of the Inserted cavity of the injection mold, a portion of the wall of the cavity. When the slider is withdrawn, at least one Part of the remaining area of the wall of the cavity is exposed, leaving the other plasticized material in this area wets the wall of the cavity.

Beyond the use of various plasticizable materials, Hollow injection molded parts can also be produced if the Injection molding a gas space is formed in the injection mold. A such gas space is by blowing a gas during the Injection molding process reached.

A large number of particularly advantageous applications open up when one plasticized material a relatively soft or rubbery and at least one other plasticized material is a relatively hard material. During that soft or rubbery material the function of a seal, a tire or takes over a handle, the relatively hard material is used to create one solid body.

Special effects are also achieved in that the plasticizable Materials at least two different colors or transparencies exhibit. While the different colors serve optical effects, it is  also possible, injection molded parts with colored and transparent areas manufacture, for example as a cover with a transparent window can be used. In particular, transparent injection molded parts, which in Sub-areas are colored with a view to prevent a view described methods can be produced particularly inexpensively.

It is also advantageous for different applications if at least plasticized material has gas inclusions. Reduce gas inclusions Weight and material expenditure and can, depending on the application, further have specific advantages.

For example, for recycling recycled particles, it is proposed that at least one plasticized material inclusions of another component having. For example, elastomers can be used in a soft material Recycled particles can be mixed in to adjust the hardness of the material.

It is particularly suitable for carrying out the method according to the invention an injection mold that has at least one sensor at the transition between partial area and remaining area of the wall of the cavity Injection mold is arranged. These sensors allow, for example, with Pressure, temperature or ultrasound meters determine when a certain plasticized material the location of the wall in which the sensor is appropriate. This allows the process to be closely monitored and control.

It is advantageous if one is primarily for the method according to the invention  usable injection mold has a paragraph at the transition between Partial area and remaining area of the wall of the cavity of the injection mold is arranged. As stated above, this paragraph allows an even one Transition line between the components.

When spraying without sprues, a two-part remains in the hot runner of the injection mold Component mixture that when injecting another part into the cavity the injection mold can get. However, this would result in contamination the outer layer of the next injection molded part. Therefore suggested that the injection mold have a hot runner with a Diverter device that allows flowing to the cavity to let plasticized material flow into an overflow. After the first Injection molding is initially carried out using the diverter incoming material is diverted into the overflow until pure material in the Channel reached. This allows the contaminants to overflow collect and then dispose of.

Ultimately, an injection molding device with a plasticizing unit and Injection unit proposed that has at least two secondary extruders are arranged between the screw tip and the nozzle tip. The usage Several secondary extruders allow different materials to be used in succession to give the injection mold in order with the method according to the invention Manufacture injection molded parts from a wide variety of materials.

The method according to the invention and a wide variety of exemplary embodiments Application of the method according to the invention are shown in the drawing  and are explained in more detail below. It shows,

Fig. 1 shows schematically a three-dimensional view of an injection molding apparatus according to the invention with a tool,

Fig. 2 shows a detail from Fig. 1 in section,

Fig. 3 is a section through an alternative embodiment of an injection molding apparatus in a schematic representation;

Fig. 4 shows a section through a lid member,

Fig. 5 is an enlarged detail of Fig. 4,

Fig. 6 shows a section through a further cover member,

Fig. 7 shows a section through a roller member,

Fig. 8 shows a section through a portion of the roller member according to Fig. 7 an embodiment with a profile,

Fig. 9 shows a section through a detail of the roller device according to Fig. 7, tires with positive connection

Fig. 10 is a section through a detail of the roller member of FIG. 7 with gas-filled tire member

Fig. 11 is a section molded by a section of a roller member of FIG. 7 from the hub forth tire member,

Fig. 12 is a section through a roller device having ball roller,

Fig. 13 is a section through a handle,

Fig. 14 is a view of a brush handle,

Fig. 15 is a section through a housing with schematically illustrated in the upper part of seal in the housing and in the lower part, shown schematically seal in the cover part and cable aperture,

Fig. 16 is a section through a cable gland,

Fig. 17 is a view of a first embodiment of a bottle stopper,

Fig. 18 is a section through another embodiment of a bottle stopper,

Fig. 19 is an injection molding with tools and

Fig. 20 shows a detail of Fig. 19 with a hot channel for runnerless syringes.

The injection molding apparatus 1 shown in Fig. 1 has a nozzle 2 which is connected to a tool 3 in connection. 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 partial area of the wall of the cavity of the tool cavity is wetted with plasticized material and only after pulling the slide 12 is a remaining area of the wall of the cavity wetted with plasticized material. 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. 2. The nozzle 2 is first connected to a partial area with a first plasticized material 13 , which is fed via the hopper 7 and the auxiliary extruder 4 . 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 the other material, 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 apparatus according to the invention is shown in FIG. 3. Here, on two sides of the tool 20 extruder 21, 22 and 23, 24 arranged. 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 . Alternatively, is also possible first to the extruder 21 plasticized material are pushed into the extruder 22, after which, the light coming from extruder 21 plasticized material is conveyed into the cavity 29 with the extruder 22 first and subsequently-provided to the extruder 22 plasticized material is replenished. The same process variants are of course also possible with the extruders 23 and 24 , it being also possible to carry out the process according to the invention 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 the device according to FIG. 3 can be used to fill up to four different materials into the cavity 29 through an opening 26 or 28 , and that the device allows a wide variety of processes to be carried out by 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. 4. 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 that solidifies on the walls of the cavity and the softer material 45 conveyed at point 41 , which flows into the mold in the middle area between the walls of the cavity.

An alternative embodiment for the production of a cover by the method according to the invention is shown in FIG. 6. 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 region 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, such a transversely disposed to the flow direction paragraph 59 is provided, which is arranged opposite a further shoulder 60. 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 member 70 with various configurations of a radially outer tire 71 to 75, FIGS. 7 to 11. The roller member 70 is in its basic version of a hub 76 and a radially adjoining tire 71st 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 of FIG. 8 provides that in the tire 72, a profile is formed. According to FIG. 9, the tire 73 is connected by means of a positive connection 81 with the hub member 76. Fig. 10 shows, finally, introducing a gas into the tire part, in order to achieve a "balloon" effect means an air bubble 82nd 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 in the middle of the hard one Component flows 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 the sprue 91 and then a soft component is injected via the sprue 92 and 93 . However, this component too, like the cover component according to FIG. 4, can 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 of a handle body 101 and a handgrip 102, a gas bubble 103 is provided preferably 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.

Fig. 14 shows a brush handle 110, in which first a soft component 111 is injected via the sprue 112 and is then injected a hard component 114 via the sprue 113th Of course, as in the other exemplary embodiments, the different materials 111 and 114 can additionally or alternatively have different colors or can be plasticizable materials with different properties in other respects.

Another common application of the described method is to manufacture a housing 120 shown in FIG. 15. This housing 120 has a need in the housing part seal 121 and disposed in a mating cover part 122 seal 123 which cooperates in the schematic representation of FIG. 15 in the upper part of the drawing in the lower part of the figure 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 embodiment 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 clamping nut 140 .

Fig. 17 shows as a further embodiment of a bottle closure 150th This bottle stopper consists of a harder component 151 , which forms the base body, and a softer component 152 , which emerges in a ring-like manner in a certain area and acts as a seal. A gas bubble 153 is provided within the harder component 151 in order to save material and to allow greater flexibility in the bottle closure.

A further 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 is for countless other applications usable, like from wheels made of hard and soft components Children's toys made of different colored components, joints made of hard and Soft components up to lids from opaque and transparent areas. Other examples are: screwdriver handles, hangers with non-slip edge, brush and toothbrush handles. Important areas of application are also conveyor belts, transport rollers and transport rollers.

The Figs. 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 lies as the core. After the end of the spraying process with component 171 , however, new component 170 has to be conveyed again and the rest of the second component 171 remaining in the hot runner 174 is usually thereby 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 to be pressed into the overflow 175 with the replenished first component 170 and the cavity 177 is only released when the first material is again present on the slide 176 . A sprue bar is no longer necessary.

In practice, the conversion from a first component to is required another experience, possibly a third, fourth, etc. component, because the timing has to be precisely coordinated. At the right time can detect in the injection molding device and in particular in the tool Sensors are attached which use pressure, temperature or ultrasound Filling the cavity with the different plasticized materials monitor. For better process monitoring, you can choose between the feeder a break from different plasticized materials. About that In addition, the displacement control of the screw, i. H. that of the snail subsidized route can be used directly to control the slide. Instead of along the way, the time from the onset of the injection process can also be measured to determine the right time for slide control. Ultimately can also use the cavity pressure as a parameter for the slide control to serve.

Claims (15)

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 be injected into the cavity through the same opening. 3. The method according to any one of the preceding claims, characterized characterized in that so much first material is placed in the injection mold is that after the other material is injected, the first material up to a paragraph in the cavity between the partial area and the remaining area extends. 4. The method according to any one of the preceding claims, characterized characterized in that after the injection of the first material at least part of the remaining area releasing slide is moved.   5. The method according to claim 4, characterized in that the slide a channel to a portion of the cavity of the injection mold releases. 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 characterized in that during the injection molding process in the injection mold Gas space is formed. 8. The method according to any one of the preceding claims, characterized characterized in that a plasticized material is a relatively soft or rubbery and at least one other plasticized material is relatively hard material. 9. The method according to any one of the preceding claims, characterized characterized in that the plasticized materials at least two have different colors or transparency. 10. The method according to any one of the preceding claims, characterized characterized in that at least one plasticized material gas inclusions having. 11. The method according to any one of the preceding claims, characterized characterized in that at least one plasticized material inclusions  another component. 12. Injection mold, characterized in that it has at least one sensor has, which at the transition between partial area and remaining area of Wall of the. Cavity of the injection mold is arranged. 13. Injection mold, in particular according to claim 12, characterized in that it has a paragraph that at the transition between subarea and Remaining area of the wall of the cavity of the injection mold is arranged is. 14. Injection mold, in particular according to claim 12 or 13, characterized characterized in that they have a hot runner with a diverter which allows plasticized material flowing to the cavity in an overflow stream. 15. Injection molding device with a plasticizing unit and an injection unit, characterized in that it has at least two secondary extruders has, which are arranged between the screw tip and nozzle tip.