EP0150716A2 - Dosing and mixing apparatus for high viscosity multiple component materials - Google Patents

Abstract

The apparatus has piston pumps (1, 4) for the pumping and dosing of the individual components and a mixing and extruding unit (7) with a static mixing tube, immediately upstream of which the components are brought together in a premixing chamber. The apparatus is distinguished by the fact that the mixing and extruding unit (7) has at least two parallel-running static mixing tubes (9, 11), between which at least one empty tube (11) is arranged, and by the fact that mixing heads (8, 10), which are fitted onto the ends and in which channels (15, 16) deflect the mixture in each case by about 180 DEG , respectively connect a static mixing tube (9, 11) to an empty tube (11) and vice versa and connect the first upstream static mixing tube to the premixing chamber, via an inlet channel (13), and the last downstream static mixing tube to a discharging nozzle, via an outlet channel (18).

Description

The invention relates to a metering and mixing device for highly viscous multi-component materials according to the preamble of claim 1.

Dosing and mixing devices are used for example for conveying, dosing, mixing and extruding highly viscous two-component materials for insulating glass sealing or for PU foam processing.

In a known metering and mixing device, the parent component and the hardener are combined in one Mixing chamber attached to the base of the device. The merged material is first mixed in a static mixing tube and then conveyed to the extrusion unit with a hose with a length of approx. 2.5 m. In the extrusion unit, the premixed material is mixed again with a static mixing tube and then discharged with a spray gun. The hose with a length of 2.5 m or more is required so that, for example, an insulating glass pane that is not moved can be sealed all around in one operation.

To clean the device after the discharge of the mixed material has ended, it is necessary to rinse the mixing chamber, the first static mixing tube, the hose, the second static mixing tube and the spray gun. This rinsing is usually carried out with a solvent, for example methylene chloride. Flushing with the base component, which would be preferable to flushing with a solvent for environmental reasons, is practically never used, since the material loss during the flushing process is large due to the large hose volume to be flushed, and the base component is usually much more expensive than a solvent.

It has therefore been proposed in US-PS 36 23 704 a metering and mixing device according to the preamble of claim 1, in which the mixing chamber is arranged after the hose, and the actual mixing process takes place only in a mixing tube. However, it has been found that - if only a static mixing tube is used for mixing - this mixing tube must have an extremely long length. The mixer result is not satisfactory for mixing tube lengths such as are used for portable extrusion units.

It is therefore proposed in DE-OS 22 02 635 a mixing and extruding unit in which the mixing tube is angled several times in order to be able to keep the portable unit reasonably short.

Surprisingly, however, it turns out that even with this known metering and mixing device according to the preamble of claim 1, material is not mixed as homogeneously as in the device described in the introduction, in which two mixing chambers connected via the working hose are provided.

The invention has for its object to develop a metering and mixing device for highly viscous two-component materials according to the preamble of claim 1 such that a homogeneous mixed material is obtained with a small volume to be rinsed before a longer service life.

This object is achieved by the features specified in the characterizing part of claim 1.

According to the invention, it has been recognized that in metering and mixing devices with piston pumps for the conveyance of the individual components of a multi-component mixture, for example a two-component mixture with base component and hardener, a partial cross-mixing, as is achieved with static mixing tubes, is not sufficient for a homogeneously mixed material. At the dead centers of the piston pumps, quantities deviating from the correct dosing are conveyed. Therefore, in order to achieve a homogeneous material mixture, it is also necessary to mix the material flow lengthways. Such longitudinal mixing takes place at the beginning described device in the approximately 2.5 m long piece of hose, but it does not take place in the known device according to the preamble of claim 1, since in this device the parent component and the hardener are only brought together after the hose.

According to the invention, therefore, in a device according to the preamble of claim 1, longitudinal mixing is forced into empty tubes which are arranged between static mixing tubes of the mixing and extruding device. The empty pipes are connected at both ends to a static mixer via mixing heads, in which the material flow is deflected by 180 °; in other words, the material runs alternately through static mixing tubes and empty tubes in a "meandering" way. Due to the turbulence caused by the deflection, longitudinal mixing, which compensates for the fluctuations in the mixing ratio due to the dead centers of the piston pumps, is already achieved in a comparatively short way in the empty pipes. This means that the volume that has to be flushed after finishing the work is small.

• Gemäß Anspruch 2 bestehen die Umlenkkanäle in den Mischköpfen, die eine 180°-Umlenkung des Gemisches bewirken, aus zwei 90°-Knieen. Durch diese Gestaltungen der Mischköpfe wird eine starke zusätzliche Längsverwirbelung hervorgerufen. Durch diese Strömungsverhältnisse wird die Längsvermischung wesentlich verbessert, so daß eine weitere Reduzierung der Länge des Leerrohres möglich ist.

Further developments of the invention are specified in the subclaims:

• According to claim 2, the deflection channels in the mixing heads, which bring about a 180 ° deflection of the mixture, consist of two 90 ° knees. This design of the mixing heads creates a strong additional longitudinal swirl. The longitudinal mixing is significantly improved by these flow conditions, so that a further reduction in the length of the empty tube is possible.

This longitudinal swirl, which is comparable to a rolling movement of the mixture, is further increased when the channels in the mixing heads "empty channels", ie channels without a static mixing insert (claim 4).

Since the measures characterized in claims 1 to 5 lead to an excellent longitudinal mixing, which - as has been recognized according to the invention - is required for a homogeneously mixed material, it is possible to increase the length of the mixing tubes and the empty tube to about 10 to 50 cm to reduce. This makes the mixing and extrusion unit with mixing chamber, mixing tubes, mixing heads, empty tube and spray gun very handy and has only a small flush volume.

The additional "S" -shaped deflection provided in accordance with claim 8 when entering or exiting the mixing heads increases the longitudinal turbulence and thus further improves the longitudinal mixing.

The small volume of the parts to be cleaned after completion of the work predestines the mixing and extruding unit designed according to the invention to be rinsed with the parent component instead of with a solvent (for example in the case of a two-component mixture). This flushing process, which has already been proposed per se, has so far not been widely used due to the high material losses and the associated high costs. However, the small volume to be flushed, due to which the material losses reach the order of magnitude of two 400 g at most, allows the device to be flushed with the parent component in an environmentally friendly manner instead of with a solvent at a reasonable cost. In particular, if the working hose is very long, the cost of the lost material in the device designed according to the invention can even be considerably lower than in the case of a conventional device which is flushed with a solvent. In any case, the multi-component metering and mixing device according to the invention for highly viscous multi-component materials has the advantage that the mixing and extruding unit according to one of claims 1 to 9 easily to existing devices in which previously the mixing chamber and a first static mixer before Working hose are arranged and the flushing was carried out with a solvent, can be retrofitted so that existing devices can be operated in an environmentally friendly manner.

In addition, it is of course also possible to use the mixing and extruding unit designed according to the invention in a multicomponent metering and mixing device for highly viscous multicomponent materials, in which rinsing with the base component and the "rinsing material" is returned to an intermediate container or the storage container for the base component .

• Figur 1 den Prinzipaufbau einer erfindungsgemäß aufgebauten Zweikomponenten-Dosier und Mischvorrichtung,
• Figur 2 einen Längsschnitt durch eine erfindungsgemäß ausgebildete Misch- und Extrudiereinheit, und
• Figur 3, 4 und 5 Querschnitte durch die in Figur 2 dargestellte Misch- und Extrudiereinheit.

The invention is described below using an exemplary embodiment with reference to the drawing, in which:

• FIG. 1 shows the basic structure of a two-component metering and mixing device constructed according to the invention,
• FIG. 2 shows a longitudinal section through a mixing and extruding unit designed according to the invention, and
• Figures 3, 4 and 5 cross sections through the mixing and extruding unit shown in Figure 2.

Figure 1 shows the basic structure of a two-component dosing and mixing device for highly viscous two-component ten materials according to an embodiment of the invention.

During the mixing and discharge phase, a piston pump 1 conveys the base component from a storage container 2 via a hose line 3 and a piston pump 4 the hardener from a storage container 5 via a hose line 6 to a mixing and extrusion unit 7, which can be connected, for example, to a spray gun .

The piston pumps 1 and 4 for conveying and metering the base component and the hardener can be designed in the known manner as double-acting piston pumps. The pumps are arranged in a metering frame and mechanically interlocked with one another via a lever beam which is infinitely adjustable within the metering range of the pumps to adjust the mixing ratio. This construction of the pumps is known, so that there is no need to go into this in the following.

FIG. 2 shows part of a mixing and extruding unit designed according to the invention. The mixing and extruding unit 7 has a first mixing head 8, a first static mixing tube 9, a second mixing head 10, an empty tube 11 and a second static mixing tube 12.

The parent component and the hardener, which have been brought together from the hose lines 3 and 6 in a mixing chamber (not shown), enter the first mixing head 8, where they are redirected twice in a double knee 13 of the inlet channel with small radii of curvature by 90 ° without them the direction of flow changes, flow through the first static mixing tube 9 and then enter the second mixing head 10. The mixture is in the second mixing head 10 through 180 ° in a channel without mixing with a The radius of curvature is redirected and flows through the empty tube 11. Then the mixture is redirected again in the first mixing head in a channel with a small radius of curvature and without a mixing insert by 180 ° and flows through the second mixing tube 12. After flowing through the "double knee" 14 in the second Mixing head 12, which forces an “S” deflection of the mixture, the mixture emerges and can be fed, for example, to a spray gun or another extrusion unit.

In the static mixing tube 9, the material brought together in the mixing chamber is initially mixed essentially only transversely, while longitudinal mixing takes place in the empty tube 11. This longitudinal mixing is strongly supported by the turbulent flow, which is caused by the two 180 ° deflections in the mixing heads and the "S" deflection.

Studies have shown that the mixture of highly viscous materials does not flow in the actual sense, but executes a kind of "rolling movement" in the empty pipe. The speed in the "rolling movement" phase is different in different layers. As a result, excellent longitudinal mixing is achieved over a short path length. This longitudinal mixing in conjunction with the transverse mixing subsequently achieved in the second mixing tube compensates for material inhomogeneities due to the uneven delivery rates of the piston pumps at the dead centers.

Another factor in the good mixing is the two 90 ° deflections in the double knees of the mixing heads after the combined material enters and before the material mixture exits.

The static mixing tubes can be constructed in a manner known per se, so that their construction need not be discussed in more detail. The length of the individual tubes is preferably between 25 and about 50 cm in the exemplary embodiment shown, so that only a small volume has to be rinsed in the rinsing process described below, and thus the rinsing losses are low.

To carry out the rinsing process, a 2-way valve 15 is switched over, so that the hardener no longer enters the hose line 6 into the mixing chamber in which the two materials are brought together, but is guided back into the storage container 5 via a hose line 16 . The hardener therefore circulates during the rinsing phase.

During the rinsing phase, the parent component continues to enter from the hose line 3 into the mixing chamber (not shown in detail) and displaces the mixing chamber 8, the mixing head 8, the static mixing tube 9, the second mixing head 10, the empty tube 11, the 180.degree. Pipe bend of the first mixing head 8, the second stasch mixing tube 12 and the spray gun and after the entire mixture of materials in the mixing and extrusion unit has emerged from the spray gun and the unit 7 contains only the base component, the rinsing process is ended When the work is started, the "pure" parent component in the mixing and extruding unit 7 has to be displaced by a material mixture with a correct mixing ratio before the sealing of insulating glass panes can be started.

The total material losses during the rinsing process and during Due to the compact design of the mixing and extrusion unit, “restart process” is low and is approximately in the order of magnitude of 400 g at the start and end of work. This makes it possible to rinse with the parent component in an environmentally friendly manner at about the same cost as in known devices which are rinsed with solvents.

Furthermore, the mixing and extruding unit according to the invention can advantageously be used in a two-component metering and mixing device for highly viscous two-component materials with recycling of the base component used for rinsing. Such a device is manufactured, for example, by Reinhardt-Technik and is described in the older German patent application P 33 177 34.1. The use of the mixing and extruding unit according to the invention makes it possible to significantly reduce the size of the intermediate container which is used for the intermediate storage of the materials expelled at the end of work and at the start of work,

Furthermore, the mixing and extruding unit constructed according to the invention can of course also be used in a device in which rinsing is carried out with a detergent such as methylene chloride.

The dosing and mixing device constructed according to the invention can of course not only be used for mixing, dosing and extruding two-component materials for insulating glass sealing, but also of any highly viscous two- and multi-component materials, such as PU foam materials.

Furthermore, it is also possible to use more than two static mixing tubes and more than one empty tube, and the one allow individual pipes to flow through the mixture alternately; the mixture then flows alternately through mixing and empty tubes on a "meandering" path.

Claims (10)

1. Dosing and mixing device for highly viscous multi-component materials with piston pumps (1.4) for conveying and dosing the individual components and with a mixing and extruding unit (7) with a static mixing tube, immediately before the components are brought together in one Premixing chamber takes place,
characterized in that the mixing and extruding unit (7) has at least two parallel static mixing tubes (9, 11), between which at least one empty tube (11) is arranged, and in that front-mounted mixing heads (8, 10) in which channels (15, 16) divert the mixture by approximately 180 °, one static mixing tube (9, 11) each with an empty tube (11) and vice versa, as well as the first static upstream via an inlet channel (13) with the premixing chamber and the downstream static one Connect the mixing tube to an outlet nozzle via an outlet channel (18) '. 2. Device according to claim 1,
characterized in that the channels in the mixing heads, which deflect the mixture through 180 °, have a small radius of curvature. 3. Device according to claim 2,
characterized in that the channels in the mixing heads for the 180 ° deflection have two 90 ° knees. 4. Device according to one of claims 1 to 3,
daduch characterized in that the channels in the mixing heads have no static mixing inserts. 5. The device according to claim 1 or 4,
characterized in that the length of the mixing tubes (9, 11) and the empty tubes (10) is approximately the same. 6. Device according to one of claims 1 to 5,
characterized in that the mixing tubes (9, 11) and the empty tubes (10) each have a length of approximately 10 to 50 cm. 7. Device according to one of claims 1 to 6,
characterized in that the total length of the empty tubes (10) is less than 50 cm. 8. Device according to one of claims 1 to 7,
characterized in that the inlet channel of the inlet mixing head (8) and / or the outlet channel of the outlet mixing head (10) have two 90 ° knees which deflect the mixture in an "S" shape. 9. Device according to one of claims 1 to 8,
characterized in that only two static mixing tubes are provided, between which there is an empty tube in the flow path of the mixture. 10. The device according to one of claims 1 to 9,
characterized in that when used as a two-component mixing device, the mixing and extruding unit (7) can be rinsed with the parent component.

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