EP1993803A1

EP1993803A1 - Device and method for producing multicomponent plastic parts

Info

Publication number: EP1993803A1
Application number: EP07704130A
Authority: EP
Inventors: Matthias Sieverding; Jochen Zwiesele; Marco Gruber; Jochen Mitzler
Original assignee: KraussMaffei Technologies GmbH
Current assignee: KraussMaffei Technologies GmbH
Priority date: 2006-03-07
Filing date: 2007-01-25
Publication date: 2008-11-26
Also published as: CN101374646A; KR20080109824A; WO2007101747A1; CA2643490A1; US20090218726A1; DE102006010310A1

Abstract

The invention relates to a method and a device for producing a plastic part that consists of a plurality of components. The device according to the invention comprises a closing unit for receiving at least one mold in which a thermoplastic molded body can be shaped or positioned, and at least one polyurethane unit for introducing a polyurethane material into a larger cavity comprising the thermoplastic molded body. The invention is characterized in that at least one additional polyurethane unit for introducing an additional polyurethane material having different product properties into the same or a different, larger cavity, is provided or in that the first polyurethane unit is adapted for an additional polyurethane material having different product properties being introduced into the same or a different, larger cavity.

Description

description

title

Apparatus and method for producing multi-component plastic parts

The present invention relates to an apparatus and a method for producing multi-component plastic parts according to the preambles of claims 1 and 9 or 16.

It is known to coat a molded part, in particular a plastic molded part, by means of a polyurethane material. In this case, a method is also already used according to which the molded part is inserted into an enlarged cavity, so that a free space is formed between the cavity wall and the inserted molded part. In this room, a polyurethane material is filled to coat the inserted plastic part. After crosslinking and curing of the polyurethane material, the mold forming the enlarged cavity can be opened and the coated product removed.

The object of the present invention is to provide an integrated system with which a thermoplastic molding can be coated with at least two different polyurethane materials.

This object is achieved in terms of apparatus by the features defined in claims 1 and 9 and procedurally by the features defined in claim 16.

In terms of apparatus, two alternative concepts are pursued. According to a first alternative, a closing unit is associated with at least two polyurethane units, each of which can fill its own, separate mold cavities formed by the closing unit, the reactive material provided by them. According to the other alternative, a mold cavity is formed by the closing unit, in which polyurethane material with different material properties can be filled into different partial cavities. The design necessary for this will be described in more detail below. Two polyurethane units can be completely separated or use different parts of the system together. Thus, it is possible to supply two mixing heads by means of a switching unit via a single metering machine. In this case, for example, a component "inline" can be gassed in order to achieve a foam effect. "Inline fumigation" can be carried out by means of a CO2 gas. Thus, it is possible, for example, in a door inner module for a motor vehicle to form the lower area in a thin-walled and compact manner with a first color and to foam the upper parapet area and make it soft with a different color. If only one PUR unit is used, the propellant can be fed separately for each shot.

A particular advantage is given by the fact that the closing unit is also assigned to a plasticizing and injecting device, which can bring the thermoplastic melt in an associated mold. In this case, in a first cycle step, the thermoplastic molded body can be formed, which is then coated in the subsequent steps with at least two polyurethane materials with different material properties. Of course, it is also possible to form a system in which two or more plasticizing and injecting devices are used.

A closing unit, which is particularly suitable for this method, is equipped with a rotatable insert, wherein the insert cooperates with at least two platens. Between the clamping plates and the intermediate insert each forming tools are arranged. Of course, three, four or more platens may be disposed around the insert. For this purpose, the insert must of course be provided with a corresponding number of surfaces for receiving the respective mold parts.

A particular advantage is given when compared to the mold for the plasticizing and injection unit, a further mold is arranged, so that the closing unit can close both molds in the manner of a sandwich process. If the insert is cube-shaped, identical mold halves can be arranged on all four sides, of which at least two cooperate with mold halves arranged on the clamping plates. In this case, the enlarged cavity or the enlarged cavities would each result in a subsequent transfer step by closing with another mold half on a backing plate.

As an alternative to reacting the - possibly already partially coated - thermoplastic molded body, this can be introduced into an enlarged cavity, which either has at least two partial cavities which are separated or in which different partial cavities are successively formed by pulling out a drawer or a core pull. Even with this procedure, advantageously, the plasticizing and injection unit can already be integrated into the system. Moreover, it is also possible to use a turning plate closing unit.

If a separating device is provided for the separation of different partial cavities, then this can preferably be formed retractable. The retraction may possibly also be done with already closed mold. Especially in the latter case, it is possible to completely fill a partial cavity, so that after opening the mold no free space remains, in which the separator was added. A particular advantage when using a plurality of partial cavities is the use of a polyurethane unit which can discharge at least two polyurethane materials with different properties in succession. For this purpose, switching mechanisms are necessary which, for example, provide different material additives (eg different color and / or a gassing of the components, such as CO ₂ ) depending on the shot selected. If the corresponding material is introduced into a cavity or into partial cavities with only a single polyurethane unit, then means for changing the flow direction are expedient. On the one hand, this can be a channel system in the molding tool, which can be switched over from its flow direction with respect to the various partial cavities. On the other hand, one polyurethane unit can be applied to different gate marks. If, in addition to the aforesaid switching possibility, a separating device is also provided, the separating device may preferably also be designed such that the switchable flow paths into the various cavity spaces can be realized with it.

Of course, it is also possible to equip the closing unit with a turntable, a sliding table or an index plate arrangement. The individual components are known per se and need not be explained in detail in the present case.

Further advantages, including procedural nature, are defined in the subclaims.

The present invention will be explained in more detail with reference to two embodiments and with reference to the accompanying drawings. The drawings show in

Figure 1 is a schematic diagram of a first embodiment of a system according to the invention, Figure 2 is a schematic diagram of a second embodiment of a system according to the invention and Figure 3 is an enlarged detail cross-sectional view of a mold with switchable flow path.

FIG. 1 shows a schematic plan view of a first embodiment of a system according to the invention. In this case, a closing unit 10 is centrally provided, of the present case, however, only platens 12, 14 and 16 and a rotatable about a vertical axis insert 18 are shown. Not shown are traction-transmitting elements such as spars or drives for opening and closing the clamping unit and for applying a closing pressure. However, these design elements are well known in the art and can be presumed for the present invention.

The insert 18 is present translationally fixed and only rotatable. On the other hand, the platens 12, 14 and 16 are respectively slidable in the direction of the insert 18 and in the opposite direction.

- A - Between each platen 12, 14 and 16 and the insert 18, a mold 20, 22 and 24 is arranged. Each of these molds consists of two mold halves 20 ', 20 "and 22', 22" and 24 ', 24 ", of which the mold halves 20', 22 'and 24' on the insert and the mold halves 20", 22 "and 24 are attached to the platens 12, 14 and 16. The mold halves 20 ', 22', 24 'and 25' are identical. In each case in cooperation of the arranged on the insert 18 mold halves with the mold halves on the platens 12, 14 and 16 results in corresponding Kavitätsräume, which will be explained below.

In the embodiment according to FIG. 1, the platen 12 is assigned a plasticizing and injection unit 26 (shown only very schematically), into which a thermoplastic starting material is introduced via a hopper 30. By means of a drive 28, the plasticizing and injecting device 26 is driven, thereby melting the starting material and injected in a conventional manner in the cavity of the mold 20. In this case, the plasticizing and injection unit 26 is shown in the back process state in Figure 1. During injection, the plasticizing and injecting device 26 is moved forward, so that its injection nozzle adjoins the sprue of the mold 20 for introducing the melt.

The platen 16 is associated with a first polyurethane unit 32 comprising a mixing head 34 with an outlet tube. The mixing head 34 can, as indicated by the double arrow, be moved in the direction of the platen 16 and opposite it. As a result, the mixing head with its outlet pipe can be coupled to a sprue area of the molding tool 24.

The mixing head 34 is connected via component supply lines 46 and 48 with two containers 38 and 40, in which the two polyurethane components isocyanate and polyol are included. These two components are supplied by means of pumps under high pressure to the mixing head 34. In addition, the mixing head 34 is connected via a feed line 52 to a paint container 50, from which a first color material is supplied to the mixing head 34. The polyurethane components and the coloring material are mixed together in the mixing head and via the outlet pipe discharged. The individual metering systems and polyurethane subunits are shown in FIG. 1 only very schematically. In practice, these systems are made somewhat more complex, but the skilled person is sufficiently known due to the diverse state of the art.

The platen 14 is associated with a second polyurethane unit 32 ', which also comprises a mixing head, which in turn, according to the double arrow, in the direction of the platen 14 and in the opposite direction thereof is movable. The drive for this - as well as the facial expressions is again not shown. Also, the mixing head 36 can couple with its outlet pipe to a sprue of the mold 22 so as to be able to transfer the polyurethane mixture in the mold cavity of the mold 22 can.

The mixing head 36 is in turn coupled to the containers 38 and 40 via the component supply lines 42 and 44 and receives from these via the pumps the components isocyanate and polyol. Of course, separate containers could be provided. Again via a supply line 56, the mixing head 36 is connected to a container 54 for a second color component.

When operating the system shown only systematically in FIG. 1, the procedure is as follows:

First, in a first cycle step, a plastic melt is produced by means of the plasticizing and injection unit 26 and injected into the cavity of the tool 20. After curing of the thermoplastic material, the platen 12 is moved away from the insert 12, and after opening the remaining platen 14 and 16, the insert can be rotated 90 ° counterclockwise (Figure 1). In this case, the thermoplastic product produced in the previous step is held in the mold half 20 'and carried along accordingly.

Now, the clamping plates 12, 14 and 16 are closed and locked again, which forms an enlarged cavity due to a corresponding shape in the mold 22. This is between the cavity wall of the Forming tool half 22 "and the product formed a space in which now by means of the approached mixing head 36, a polyurethane material is injected.

After at least partial curing (crosslinking) of the polyurethane material, the mixing head 36 and also the clamping plate 14 - as well as the other platen 12 and 16 - back process in an opposite direction to the insert plate 18, so that the insert 18 free by 90 ° can turn counterclockwise. After a further closing of the platens 12, 14 and 16, a further enlarged cavity is formed in the mold 24 with appropriate formation of the mold half 24 ", in the after approaching the mixing head 34, another polyurethane material with a different material property, eg. a different color, can be injected.

Depending on the configuration of the various cavities in the molds 22 and 24, a thermoplastic part coated with different polyurethane materials can thus be produced. If, after the opening of the clamping plates 12, 14 and 16, the turning plate 18 is again rotated by 90 °, then the finished product can be removed at the lower picture position in FIG.

All of the above-mentioned method steps can be carried out in the same cycle; This means that in the cavities of the molds 20, 22 and 24 respectively corresponding materials can be introduced at the same time and at least partially harden in the cavities, so that the insert 18 after opening the platens 12, 14 and 16 can be further rotated.

Of course, other devices can be added to the system shown in FIG. Thus, the two molds 22 and 24 can be assigned injection devices for introducing a release agent onto the cavity surface of the mold halves 22 "and 24". Furthermore, it is possible to provide a removal robot or a robotics for inserting a part.

FIG. 2 shows a somewhat modified embodiment of a present system according to the invention compared to the illustration in FIG. Now, as compared to Figure 1, the platen 14 as well as the second Polyurethane unit 32 'omitted. For this, the mixing head 34 'is provided in a modified form. Namely, the mixing head 34 'is now adapted for switching the supply of an additive or additive, which can be added to the polyurethane components polyol and isocyanate.

Thus, the mixing head 34 'is connected via the supply line 56' to a container 54 ', from which the second color can be supplied to the mixing head 34'. Depending on the shot, the mixing head 34 'now mixes either the first color component or the second color component with the two reaction components polyol and isocyanate and injects this different mixture into partial cavities of the enlarged cavity in the mold 24.

For this purpose, it is of course necessary that the material to be filled can be introduced in a desired manner in a predetermined Teilkavität. An embodiment with which this is possible, for example, is shown in FIG. FIG. 3 shows a schematic detail sectional view of a molding tool, as it can be installed as a molding tool 24 in FIG. 3 includes a first mold half 60 'and a second mold half 60 ", and the first mold half 60' may be attached to the insert.

Between the two mold halves 60 'and 60 ", a cavity is formed, in which a thermoplastic molded body 68 is already arranged. Between the thermoplastic body 68 and the cavity wall of the mold half 60", a cavity with two partial cavities 66' is provided in an enlarged cavity. The two partial cavities 66 'and 66 "are separated by a separating ruler 70, so that they have no connection to one another. The separating ruler 70 is fixed to the mold half 60 "and extends in a closed manner with the mold closed to the thermoplastic molding 68th

In the mold half 60 "a channel system is formed, wherein - starting from the sprue 62 - a main channel extends to a junction and from there into two sub-channels 62 'and 62" splits. These sub-channels in turn lead into the sub-cavities 66 'and 66 ". At the branch point is a switching device in The circuit is indicated by the double arrow Depending on the switching position, the flow path is either from the sprue 62 to the partial cavity 66 'or from the sprue 62 to Teilkavität 66 "realized. In combination with the mixing head 34 ', depending on the operation of the mixing head, first a first polyurethane material having a first material property can now be filled into the partial cavity 66'. Thereafter, the deflecting flap is switched over and a polyurethane material filled with a second material property in the second Teilkavität. After at least partially crosslinking and curing of the polyurethane materials, the tool 60 'can be opened and the finished part removed.

Of course, a variety of other measures for filling different partial cavities are known. So it is possible to provide separate flow channels in different sub-cavities, in which case the mixing head must be implemented from one to another sprue. It is also possible to work with core pulls or slides, which are withdrawn after filling a partial cavity to form a further partial cavity, in which case a further polyurethane material with a different material property is filled into the newly created partial cavity in a subsequent step.

With regard to the material property, the addition substances can be changed so that the haptics, for example, the softness or hardness of the material changes, also different structures can be created in this way. Of course, it is also possible to use not only two, but several separate polyurethane units or polyurethane units (mixing heads) with several switching and variation options in order to be able to provide an even greater combination of materials.

Overall, the present invention enables a versatile coating of a thermoplastic material or generally a liner with at least two or more polyurethane materials having different material properties. LIST OF REFERENCE NUMBERS

Clamping unit First chuck Second chuck Third chuck Rotatable insert First mold ', 20 "First mold mold halves Second mold, 22" Second mold mold halves Third mold', 24 "Third mold mold halves" Mold half Plasticizing and injection unit Drive funnel, 32 ' , 32 "Polyurethane Unit (PUR Unit), 34 'First Mixing Head Second Mixing Head Polyol Container Isocyanate Container Isocyanate Feed Line to Second Mixing Head Polyol Feed Line to Second Mixing Head Isocyanate Feed Line to First Mixing Head Polyol Feed Line to First Mixing Head First Color Paint Tube Color Line to first mixing head, 54 'container with second paint, 56' paint line to the second / first mixing head Detail section of a molding tool ', 60 "mold halves with molding cavity PUR supply channel', 62" PUR subchannel , 64 'Switchable diverter flap', 66 Mold cavity

Thermoplastic product

metal ruler

Claims

claims

A system for producing a polyurethane-coated thermoplastic part comprising

- A closing unit (10) for receiving at least one mold (20, 22, 24), wherein a thermoplastic molded body (68) is positioned in an enlarged cavity and

- At least one polyurethane unit (32) for introducing a polyurethane material into at least a portion of the enlarged, the thermoplastic molded body receiving cavity, characterized in that at least one further polyurethane unit (32 ') for introducing a further polyurethane material is provided with other product properties in another part of the enlarged cavity or in another enlarged cavity.

2. System according to claim 1, characterized in that each polyurethane unit (32, 32 ') is assigned its own separate mold (22, 24) in the closing unit (10) for introducing the associated polyurethane material.

3. System according to claim 1, characterized in that at least two polyurethane units (32, 32 ') are associated with a single mold (22, 24) in the closing unit (10) for introducing the associated polyurethane material.

4. System according to any one of claims 1 to 3, characterized in that a plasticizing and injection unit (26) for processing thermoplastic melt and an associated, in the closing unit (10) arranged molding tool (20) is provided in the introduction of the thermoplastic melt is possible.

5. System according to one of claims 1 to 3, characterized in that at least two plasticizing and injection units (26) for processing thermoplastic melt and one or more associated, in the closing unit (10) arranged molding tools (20) are provided in the a contribution of the thermoplastic melt is made possible.

6. System according to any one of the preceding claims, characterized in that the closing unit (10) a rotatable insert (18) and at least two with the insert (18) cooperating clamping plates (12, 14, 16) summarizes, wherein between the platens (12, 14, 16) and the insert (18), the molds (20, 22, 24) are arranged.

7. System according to claim 6, characterized in that the insert (18) is cube-shaped and on all four sides identical mold halves (20 ', 22', 24 ', 25') are arranged, of which at least two of the clamping plates (12, 14, 16) arranged mold halves (20 ", 22", 24 ") cooperate.

8. System according to any one of the preceding claims, characterized in that the closing unit (10) is equipped with a turntable, a sliding table or an index plate.

9. system for producing a polyurethane-coated thermoplastic part comprising

- A closing unit (10) for receiving at least one mold (20, 24), wherein a thermoplastic molded body (68) is positioned in an enlarged cavity and

- At least a first polyurethane unit (32 ") for introducing a first Polyurethane material in at least a portion of the enlarged, the thermoplastic molding cavity receiving cavity, characterized in that the first polyurethane unit (32 ") for introducing a further polyurethane material with other product properties in another part of the enlarged cavity or in a another enlarged cavity is provided.

10. System according to claim 9, characterized in that at least one plasticizing and injection unit (26) for processing thermoplastic melt and an associated molding tool (20) is provided, in which an introduction of the thermoplastic melt is made possible.

11. System according to one of claims 1 to 10, characterized in that the polyurethane unit (32 ") is associated with its own mold (24) in the closing unit for introducing the polyurethane material, wherein the enlarged cavity at least two Kavitätsräume (66 ', 66 ") which are alternately connectable to the runner (62) fluidly.

12. System according to any one of claims 1 to 11, characterized in that a separating device (70) for the separation of an enlarged cavity in at least two Kavitätsräume (66 ', 66 ") is provided.

13. System according to claim 12, characterized in that the separating device (70) switchable, in particular from the cavity is retractable.

14. System according to claim 113, characterized in that the separating device (70) is designed so that it is closed even when closed A mold (60) is retractable from the cavity.

15. System according to any one of claims 12 to 14, characterized in that the separating device is designed such that thus the switchable flow path is realized in different Kavitätsräume.

16. A method for producing a polyurethane-coated thermoplastic part, in which a thermoplastic body is inserted into a cavity or formed in a cavity, a larger cavity is formed with inserted thermoplastic body and at least the part of a cavity filled with a polyurethane material is, characterized in that at least one further polyurethane material with a different material property in a further cavity or another part of a cavity, which is also limited by the thermoplastic body is at least partially introduced.

17. The method according to claim 16, characterized in that in a first step, the thermoplastic part is formed in a first cavity, that the thermoplastic part is converted into another larger cavity and a polyurethane material is filled in the enlarged cavity that the thus formed Body is converted back into a larger cavity and a polyurethane material with a different material property in the larger

Cavity is filled.

18. The method according to claim 16, characterized in that in a first step, the thermoplastic part is formed in a first cavity, that the thermoplastic part is converted into another larger cavity that a polyurethane material at least in a part of the enlarged cavity is filled, and a polyurethane material is filled with a different material property in another part of the enlarged cavity.

19. The method according to claim 18, characterized in that the cavity is further increased after filling of the first polyurethane material.

20. The method according to claim 19, characterized in that the enlargement is carried out by pulling out a Kernzuges or a slide-in part.

21. The method according to claim 18 to 20, characterized in that the flow path is switched within a mold after the filling of the first material, such that the second material is filled in a further step in another Teilkavität.