WO2006069849A1

WO2006069849A1 - Mixing head provided with a sealing collar

Info

Publication number: WO2006069849A1
Application number: PCT/EP2005/056034
Authority: WO
Inventors: Hans Jürgen Kern; Robert Brunner
Original assignee: Krauss-Maffei Kunststofftechnik Gmbh
Priority date: 2004-12-23
Filing date: 2005-11-17
Publication date: 2006-07-06
Also published as: DE102004063375A1

Abstract

The invention relates to a mixing head for processing and introducing a thermosetting material into a closed mould, wherein said mixing head comprises an outlet pipe having a discharge channel through which the thermosetting material in introduced into the closed mould. The aim of said invention is to obtain, while introducing the material into the closed mould, a seal between a sealing head and the closed mould or an insert. For this purpose, a sealing device (41, 46, 48) is provided at the end of the outlet pipe on the output side and interacts with the mould or an element inserted therein in such a way that the seal is produced.

Description

MIXING HEAD WITH SEALING CUFF

description

The invention relates to a mixing head according to the preamble of claim 1.

Mixing heads for processing thermoset materials, especially polyurethane, are well known. In this case, for example, two materials are intimately mixed in a mixing chamber and discharged through a discharge channel into a mold. The reaction then takes place in the mold, usually at elevated temperature, whereby a correspondingly formed product can be formed corresponding to the mold surface. In particular, with regard to the production of large-sized and provided with a foam-backed construction, for example, for the interior of motor vehicles, such applications are realized.

Often the thermoset material mixed with one another from the reaction components is introduced into an open mold, the mold is then closed and the reaction is carried out. However, in order to increase the efficiency of such a production process, it is also known to no longer fill an open mold with the thermoset starting material and then to close it, but to fill a self-contained mold via an injection point, as is the case with injection molding. is already known for thermoplastic materials in itself. It is already known, a hollow mold - also called cavity - provide that is evacuated, for example, during the introduction of a reaction mixture and to keep this mold closed until the end of the reaction time. For this purpose, the mixing head, with which the reaction mixture is fed into the mold, usually connected to the end of the reaction time with the filling opening.

In DE 42 16 393 a post-mixer for a mold of the RIM technique is described. Such a post-mixer is used to mix the reaction mixture formed in a mixing head again - possibly better - with each other. An embodiment of such a post-mixer is proposed in DE 42 16 393, which may also remain in a product as a "lost element." This post-mixer has at its front mouth region a sealing lip which seals the post-mixer accommodated in a mold on both sides - should ensure. A sealing device on the mixing head and in particular a sealing of the mixing head relative to the post-mixer is not addressed in DE 42 16 393.

DE 101 30 650 describes a method for introducing liquid into a mold. In this case, the outflow end of a conveyor is screwed to an outer layer of a later composite element. In a preferred embodiment, an O-ring may be placed between a mixing head and the outer layer of the later composite element for sealing.

In DE 103 00 101 A1 a process for the production of polyurethane moldings is described, in which although it is mentioned that the mixing head can dock before each shot with a special mixing head portal or manually to the tool. However, a seal between the mixing head and a mold is not described in DE 103 00 101 A1.

DE 1 554 999 deals with a device for producing molded parts. In this case, a thermal seal or thermal insulation is provided between an ejection cylinder and the filling opening of a mold. From DE 1 554 999, however, it is not clear whether this seal also represents a pressure-tight seal and whether this seal is loosely inserted between the ejection cylinder and the filling opening or attached to an element.

The problem with all known mixing heads in general that material could escape in the transition region to the mold to the outside environment, which should be prevented.

The object of the present invention is therefore to specify a mixing head in which these problems are avoided. The object is achieved by a mixing head according to the features of claim 1.

A central idea of the present invention is the outlet-side arrangement of a sealing device on the mixing head, wherein the sealing device cooperates sealingly with a tool or a part inserted in a tool. In this case, a sealing collar is provided as a sealing device, which is arranged at least at the outlet end of the outlet pipe.

The sealing sleeve can also extend over the essential area of the outlet pipe and can even be supported on the housing side.

According to a particular embodiment, an annular groove is provided on the outlet-side end face of the sealing collar, which results radially outside or inside an annular projection, which can be pressed with high surface pressure sealing in a more or less elastic inserted part. Since no excessive pressures occur when introducing the reaction mixture, such a patch seal is very efficient and effectively prevents the escape of the reaction mixture to the environment.

The sealing collar may be made of steel or a harder plastic material, which preferably cooperates with a more elastic material which may be formed as a pickled part.

Alternatively, however, the sealing collar can also consist of two or more materials, with a more elastic material being provided on the outlet side. Both materials of the sealing sleeve can be positively connected to each other via undercuts, so that a separation of the two parts is not readily possible.

According to a preferred embodiment, the sealing collar is closed substantially flush with the outlet end of the outlet pipe. This is particularly helpful if only the outer part of the sealing collar in a sealing manner with a corresponding part of either the tool or an inserted part cooperates. In this case, in particular only the outlet pipe itself comes into contact with the reaction mixture to be introduced into the tool. Thus, adhesion of the reaction mixture to the sealing material itself is substantially prevented.

But the sealing sleeve can protrude axially over the outlet pipe and cover this outlet side at least partially. In this case, a seal between the tool and the outlet pipe or between the inserted partition and the outlet pipe would come to rest.

Alternatively, it is entirely possible to dispense with a complete sealing collar in which a sealing element, which is preferably annular, is placed on the outlet-side end face of the outlet pipe and at least partially covers the outlet pipe. A particular embodiment is given when the outlet pipe and the sealing element are positively connected to each other, for example, by an end face of the outlet pipe annularly formed, undercut groove in the corresponding projections of the sealing element are resilient and latching used. Concrete embodiments of the present invention are explained in more detail with reference to the accompanying drawings. The drawings show in:

Fig. 1: a schematic detail view of an inventively designed

Outlet pipe, which is introduced in a tool and

2a-c: three embodiments for sealing arrangements on the outlet side

Front side of the mixing head.

In Fig. 1, only the outlet-side tip of a mixing head is shown substantially. This part of the mixing head comprises an outlet pipe 22, in which a channel (not shown) which opens into a mixing chamber is provided, through which a reaction mixture can be discharged. In the illustration in Fig. 1, a portion of a cleaning piston 24 is arranged in this channel, which - as the name suggests - is designed for cleaning the channel and cycle is moved forward for cleaning purposes. When introducing the reaction mixture itself, this cleaning piston 24 is withdrawn. In the present embodiment, the outlet pipe 24 is surrounded by a sealing collar 26 made of steel. The sealing collar and the outlet pipe 24 terminate at the outlet-side end face substantially flush. In this case, a circumferential annular groove 26 is introduced in the end face of the sealing collar, so that radially outside the annular groove, a circular projecting edge is formed.

The outlet pipe 24 is presently introduced into a conical opening 28 of a tool. The conical opening serves for a better introduction of the outlet channel 22 into the injection opening.

The tool itself consists in the present case of a lower mold 10 and an upper mold 12. Both tools 10 and 12 are shown only in part. Between the two tools 10, 12 a Kavitätsraum is formed, wherein in the present case on the bottom of the lower tool a skin 14 and in the region of the upper tool an insert 16 are arranged. The skin 14 and the insert 16 were inserted into the opened tool. Then the tool is been concluded. In the area of the injection opening, the insert 16 has a cylindrical sprue support 18, which ensures that the insert 16 does not fall down in the region of the sealing edge 20. Rather, the crown-shaped sprue support 18 supports the insert 16, wherein flow openings are formed to the rest of the cavity. When inserting the outlet pipe 22 into the conical opening of the annular projection of the existing steel sealing sleeve 26 comes to rest on the sealing edge 20 of the insert, whereby a high surface pressure arises, resulting in a complete seal against the outside environment. In this state, the reaction material can be introduced via the discharge tube 22 (with the cleaning piston 24 retracted) into the cavity and in particular between the skin 14 and the insert 16. In this case, the starting material flows through the openings of the crown-shaped sprue support 18 into the cavity space. Is the introduction of material completed, a cylindrical Abdichtschieber 30 is provided in the lower mold 10, which moves upwards and presses the skin 14 against the insert.

In Fig. 1 in this context - separated by the solid line - two alternatives are given. In an alternative - left side - the cylindrical Abdichtschieber is disposed substantially immediately below the crown-shaped sprue support and has at the upper end a corresponding crown-shaped configuration, so that the projections of the crown-shaped sprue support 18 engage in the recesses of the Abdichtschiebers 30 and vice versa. In this interlocking manner, a seal is made possible.

In the other alternative shown in FIG. 1 - right side of the image - the cylindrical Abdichtschieber is annular on its front side and arranged radially outside the crown-shaped sprue support. If the sealing slide is now moved upwards, it pushes the skin 14 radially outward of the crown-shaped sprue support in a fully sealing manner against the insert part In each alternative described above, the cavity is closed in this area and the mixing head can return to the outlet pipe 22 without the reaction material introduced in the cavity and not yet cured flowing back again and exiting at the inlet opening.

The seal between outlet pipe and mold but can also be achieved in other ways. This will be described with reference to Figures 2a to 2c. FIG. 2 a corresponds in its embodiment to that embodiment in FIG. 1.

FIG. 2 b shows another embodiment variant for a sealing arrangement at the outlet-side end of the outlet pipe. Thus, the mixing head 40 according to FIG. 2b has an outlet pipe 42 which corresponds to the outlet pipe 22 from FIG. 1 (reference number 42 in FIG. 2a). However, the sealing sleeve 41 'is no longer formed from a single material. Rather, it consists at the discharge end of the sealing sleeve of a second material 50, which forms the flush termination with the outlet pipe 42. From the dimensioning, the two sealing sleeves 41 and 41 'do not differ. Only on the material condition at the discharge end. The second material 50 of the sealing sleeve 41 'can be chosen to be very elastic, so that a support is also possible directly on very hard inserts or on the tool. Of course, the outer contours of the sealing sleeve 41 'can also be designed differently. In the present case, the shapes of the two materials are chosen so that they engage in a form-fitting manner in order to prevent the sealing sleeve from being dissolved.

Another alternative embodiment of a sealing device is shown in Fig. 2c. Here, too, a sealing collar 41 "with a softer material 52 arranged on the front side is provided in the case of a mixing head 40" with a discharge pipe 42 '. However, here on the one hand, the outlet pipe 42 'in the front region is slightly conical. The sealing sleeve as well as the second elastic material 52 project beyond the outlet tube axially and surround it at the front. In this embodiment, the sealing collar 41 "can also be pressed directly to an insert or a tool, in particular a ring-shaped sealing portion between the insert or the tool on the one hand and the outlet pipe on the other comes to rest. This relatively high contact pressures can be realized here. This may prove necessary if the injection pressures have to be chosen a little higher.

Overall, the present invention provides a simple way to make the introduction of a reaction material in a closed mold without material exiting to the outside environment.

LIST OF REFERENCE NUMBERS

lower tool

upper tool

skin

depositors

crown sprue

Sealing edge design

Outlet tube mixing head

cleaning piston

sealing sleeve

Conical insertion aid

Sealing slide, 40 ', 40 "Front part of a mixing head, 41', 41" Sealing sleeve, 42 'spout

ring groove

annular projection

Separate sealing element, first variant

Separate sealing element, second variant

Claims

claims

1. Mixing head for processing and introducing thermoset material into a closed mold, wherein the mixing head has an outlet pipe (22, 42, 42 ') with a discharge channel (44) through which the thermoset material in the closed tool (10, 12) is discharged, characterized in that at the outlet end of the outlet pipe (22, 42, 42 ') a sealing device (41, 41', 41 ", 48, 50, 50, 52) is provided, which with a tool or a in a tool inserted part (20) sealingly cooperates, wherein the sealing device in the form of a sealing collar (41, 41 ', 41 ") is formed, which is coaxial with the outlet pipe (22, 42, 42') is arranged.

2. Mixing head according to claim 1, characterized in that the sealing collar (41, 41 ', 41 ") extends substantially over the entire outlet pipe (22, 42, 42') and the housing side is supported thereon.

3. Mixing head according to one of claims 1 or 2, characterized in that on the outlet-side end face of the sealing collar, an annular groove (46) is provided, whereby radially outside and / or within an annular projection (48) is formed.

4. Mixing head according to one of claims 1 to 3, characterized in that the sealing collar (41, 41 ', 41 ") is at least partially made of steel.

5. Mixing head according to one of claims 1 to 3, characterized that the sealing sleeve consists at least partially of a hard plastic material.

6. Mixing head according to one of claims 1 to 5, characterized in that the sealing collar (41 ', 41 ") consists of two materials, wherein a more elastic material (50, 52) is provided on the outlet side.

7. mixing head according to claim 6, characterized in that both materials are positively connected to each other.

8. Mixing head according to one of claims 1 to 7, characterized in that the sealing collar (41, 41 ') terminates substantially flush with the outlet-side end of the outlet pipe (42).

9. mixing head according to one of claims 1 to 7, characterized in that the sealing collar (41 ") projecting axially beyond the outlet pipe (42 ') and this at least partially covers the outlet side.