DE102007036472B3 - Device for mixing and applying reactive plastics, uses motorized rotary mixer with discharge jet with two dosing devices for plastics components - Google Patents

Abstract

A mixing/application device has a mixing head (10) with mixing chamber (12) containing a motorized rotary mixer (18) and with an discharge jet (16) with two dosing devices for the plastics components bring mixed, in which each dosing device has a cylindrical dosing chamber (30) and a connecting dosing channel (32), an axially controlled dosing piston (36), a dosing valve (34) and a filling channel (48) with filling valve (50).

Description

The The invention relates to a device for mixing and application of reactive plastics.

On Many technical fields use plastics that are made two or more liquid ones or pasty Components exist. These plastic components become one with each other mixed and react with each other, whereby the plastic hardens. Important is that the plastic components as well as possible and in as possible exactly metered ratio be mixed together and applied before curing.

From the DE 295 16 188 U1 a device for mixing and applying reactive plastics is known, which has a mixing head with a mixing chamber in which a motor-driven rotary mixer is arranged. Dosing devices are attached to the mixing head, through which in each case the plastic components to be mixed are metered into the mixing chamber. The rotating mixer mixes the components dynamically and dispenses them through an ejection nozzle that attaches axially to the mixing chamber for application. The metering devices are separate components mounted on the mixing head, resulting in a complex construction and assembly. The overall dimensions of the device are relatively large due to the attached metering devices. The metering devices have needle valves which open or close the supply of the plastic components by axial movement in the metering volume. The separately applied metering devices result in larger flow distances of the components. The axial stroke movement of the valve needle in the metering volume causes pressure fluctuations in the supplied components. This can lead to difficulties when plastics are to be applied in very small quantities.

From the DE 10 2004 042 728 A1 is a device for the metered application of liquid or pasty plastic known. The plastic is passed through a valve designed as a valve filling valve in a metering chamber. From the metering chamber, the plastic passes through a metering valve designed as a slide valve to a discharge nozzle. A metering piston is displaceable in the metering chamber in order to convey the plastic from the metering chamber to the discharge nozzle. The metering chamber bends at right angles into the direction of flow of the metering valve and the discharge nozzle, resulting in an unfavorable course of flow. A mixture of several plastic components is not provided.

From the US 6,932,243 B2 For example, a device for mixing and applying reactive plastics is known in which a dynamic mixer arranged in a mixing chamber mixes and dispenses the plastic components. The components are supplied from cartridges that are parallel to the axis of the mixer drive. The plastic components pass from the cartridge directly into the mixing chamber, without an additional metering device being provided for the exact metering of the supplied plastic components.

From the DE 203 19 813 U1 a device for mixing and metered discharge of reactive plastics with a mixing head is known. In the mixing head, a mixing chamber is formed, in which a motor-driven rotary mixer is arranged. An outlet nozzle adjoins the mixing chamber axially. Two metering devices for the plastic components to be mixed in each case have a cylindrical metering chamber, a metering channel axially aligned with the metering chamber, which opens into the mixing chamber, a metering piston which can be axially displaced in the metering chamber and a filling channel opening laterally into the metering chamber.

Of the Invention is based on the object, a device for mixing and applying reactive plastics to sheep especially for the exact mixing and application of even the smallest Quantities is suitable.

These The object is achieved by a device having the features of patent claim 1.

advantageous versions The invention are specified in the subclaims.

The inventive device is particularly suitable for mixing and application of smallest Amounts of plastic. This means that the dosage of the supplied plastic components with high accuracy, so that even with small amounts supplied the mixing ratio exactly can be complied with. The mixture of the supplied components takes place in the mixing chamber by a dynamic mixer, the dimensions the mixing chamber and thus the mixer are kept small, too to ensure intimate mixing for small quantities and be able to keep the reacting quantities very small.

The metering devices for the respective components have a metering chamber, which opens axially aligned via a metering channel into the mixing chamber. This is a very short and straight flow path for the dosed in the Mischkam supplied to mer supplied components. The feed path has no corners and edges, which could lead to dead volumes, in which the material can settle. The supply of the component from the metering chamber into the mixing chamber is effected by a metering chamber in the axially displaceable metering. The movement of the metering piston is controllable, using a hydraulic or electric drive of the piston is used. The piston movement can thus be precisely controlled, so that on the one hand, the supplied amount of the component can be accurately metered and on the other hand, the pressure of the component in the metering chamber can be kept low. The transition from the metering chamber to the metering passage opening into the mixing chamber is closed by a metering valve operating without displacement, in particular by a slide valve movable transversely to the flow direction. The opening and closing of the metering valve therefore does not lead to any pressurization of the flowable component, which could lead to pressure fluctuations and thus dosage inaccuracies.

Of the Pressure in the metering device can thus be very accurate and constant be respected. In particular, this pressure can be kept very low be because of the flow path from the metering chamber into the mixing chamber is short and straight and thus little flow resistance offers, which would have to be overcome by a pressure build-up. The Device is therefore particularly suitable for mixing and applying highly filled Plastic material, eg. B. of silver-filled electrically conductive Plastic. Because this highly filled Material is expensive, it is of particular advantage that this Material can be precisely dosed in the smallest amounts. Besides, they are the short ways and the small volumes of advantage, because only small Material losses during flushing incurred the device. The low pressures with which the plastic components supplied in particular, are in the processing of highly filled materials also beneficial because these materials tend to that at higher To press, z. B. from about 4 bar of the filler sedimented, settles and clumps.

Essential is further that the metering devices completely integrated in the mixing head are. The metering chambers and those from the metering chambers into the mixing chamber leading metering channels are directly in a housing receiving the mixing chamber block educated. This results in optimally short and simple flow paths for the plastic components.

at a mixing head of two diametrically arranged metering devices is a narrow construction possible. Thereby can several mixing heads next to each other be arranged at a small distance of the discharge nozzles.

The exact dosage of even the smallest amounts of the supplied plastic components allows a wide range of variation for the mixing ratio of the components supplied. Even with small amounts, the mixing ratio can be set variably in a range of 100: 100 to 100: 5. The dynamic mixer preferably has a servo drive with a very precisely adjustable speed, so that here too an optimal adaptation to the properties and the amount of plastic components is possible. With the device according to the invention metering can be achieved below 50 mm ³ s ^-1 .

In the following the invention will be explained in more detail with reference to an embodiment shown in the drawing. The only one shows 1 an axial section through the device.

In the embodiment the device is shown in an embodiment, the two metering devices has, so that two plastic components reacting with each other A and B can be processed. It is obvious that, if necessary, more as two metering devices can be provided, if a larger number to be mixed by components. Further dosing devices are in agreement with the following described and shown in the drawing Dosing built up. The dosing devices are depending on their number at the same mutual angular distance about the vertical Arranged axis of the device.

The device has a mixing head 10 on, which is designed as a one-story housing block. The mixing head 10 has an axially centrally vertical bore, the lower end of a circular cylindrical mixing chamber 12 forms. The lower wall of the mixing chamber 12 is from an attached nozzle cover 14 formed, in which axially aligned with the mixing chamber 12 and connected to this a discharge nozzle 16 is used. In the mixing chamber 12 is a mixer 18 used that over a shaft 20 is driven in rotation. A seal 22 encloses the wave 20 and seal the mixing chamber 12 at its upper end. The wave 20 is by means of a ball bearing 24 rotatable in the mixing head 10 stored, one being the shaft 20 enclosing helical compression spring 26 the mixer 18 at the seal 22 abutting so that no dead space in the mixing chamber 12 above the mixer 18 arises. The upper end of the shaft 20 is with one on top of the mixing head 10 flanged drive motor 28 coupled. The one with the wave 20 axially aligned drive motor 28 is preferably as a servo drive with adjustable control ter speed formed.

In the illustrated embodiment, two plastic components A and B of the mixing chamber 12 fed. For supplying each of these components, a metering device is provided. These metering devices are diametrically opposite each other with respect to the central axis of the mixing head, ie with respect to the axis of the shaft 20 and the mixer 18 arranged. Since the two metering devices have the same structure, the following description applies to both metering devices.

Each of the metering devices has a metering chamber 30 on, which has the shape of a hollow cylindrical bore. At its inner end is the dosing chamber 30 in a dosing channel 32 over, the axially aligned with the metering chamber 30 followed. The dosing chamber 30 and the dosing channel 32 are in the housing block of the mixing head 10 designed and arranged so that its axis coincides with the vertical axis of the mixing chamber 12 or the mixer 18 an acute angle of z. B. includes about 60 °. The dosing channel 32 flows with its inner end at the upper end of the mixing chamber 12 in the outer circumferential surface. In the dosing channel 32 is at the transition from the dosing chamber 30 a metering valve 34 used. The metering valve 34 is designed as a slide valve and can be perpendicular to the axis of the dosing 32 be moved between a dosing 32 releasing open position and one the dosing 32 closing closed position. The actuation of the metering valve 34 can be electromagnetically, hydraulically or pneumatically.

From the dosing channel 32 opposite outer end of the metering chamber 30 is a dosing piston 36 in the dosing chamber 30 axially insertable, wherein the metering piston 36 has a smaller diameter than the metering chamber. Following to the outer end of the dosing 30 encloses a seal 38 the metering piston 36 and closes the dosing chamber 30 sealing off. The metering piston 36 is with its outer from the mixing head 10 outstanding end coupled with a metering drive. In the illustrated embodiment, the metering is an outside of the mixing head 10 flanged cylinder-piston unit, which is an outer cylinder 40 with a piston 42 in which the metering piston 36 is attached. The piston 42 is for example about two pressure chambers 44 and 46 Both sides with fluid pressure, in particular hydraulic, acted upon. A control ensures a precisely controllable movement of the piston 42 and thus the dosing piston 36 ,

It is readily apparent that the metering z. Belly a controlled electric drive can be.

Axially parallel to the mixing chamber 12 or the mixer 18 leads from the top of the mixing head 10 a filling channel 48 in the dosing chamber 30 , The filling channel 48 flows into the dosing chamber 30 in the area of its outer end. In the filling channel 48 is a filling valve 50 used. The filling valve 50 is preferably also designed as a slide valve, which is perpendicular to the axis of the filling channel 48 is displaceable between a filling channel 48 releasing open position and one of the filling channel 48 closing closed position. Also the filling valve 50 can be operated electromagnetically or by fluid pressure.

On one at the top of the mixing head 10 arranged connection piece 52 of the filling channel 48 can a cartouche 54 be placed, containing the respective plastic component A or B. The cartouche 54 is at its opposite end by a sliding plug 56 locked. The stopper 56 can by pressurizing in the cartridge 54 be moved to the component A or B in the filling channel 48 to push. For this purpose, pressure cylinders are on the device 58 above the mixing head 10 attached, with a spring-loaded sealing piston 60 are equipped. The sealing piston 60 gets to the end of the cartridge 54 put on, seals the cartridge 54 and presses it onto the connecting piece 52 , Through the sealing piston 60 is compressed air from the pressure cylinder 58 into the cartouche 54 initiated to the stopper 56 to move. For easy change of cartridges 54 becomes the sealing piston 60 against the spring force from the cartridge 54 pulled, whereby this can be removed and replaced by a new one.

Because the cartridges 54 and their respective driving impression cylinders 58 axially parallel to the axis of the drive motor 28 on top of the mixing head 10 are arranged, resulting in a space-saving arrangement of the cartridges 54 and the printing cylinder 58 ,

The device shown in the drawing works in the following way:
To the dosing chamber 30 to fill, the filling valve 50 in the open position and the metering valve 34 brought into the closed position, as shown in the drawing for the left metering device. The metering piston 36 is removed from the dosing chamber by means of its metering drive 30 pulled outwards so that he is the dosing chamber 30 releases. Now, the plastic component A or B from the cartridge 54 through the pressurized plug 56 over the filling channel 48 in the dosing chamber 30 be introduced until it is filled with the component A or B.

During operation, then the filling valve 50 in the closed position and the metering valve 34 switched to the open position, as shown in the drawing for the right metering device. The piston 42 the metering drive is now advanced under control, whereby the metering piston 36 axially into the metering chamber 30 Penetrates and settles in this dosing chamber 30 located plastic component through the dosing 32 into the mixing chamber 12 repressed. The rotary driven mixer 18 mixes over the dosing channels 32 in the mixing chamber inflowing components A and B and gives them over the discharge nozzle 16 out.

The diameter of the dosing piston 36 and via the metering adjustable adjustable feed rate of the metering piston 36 determine the case of the two dosing each in the mixing chamber 12 supplied amount of components A and B. In this way, the mixing ratio can be set adjustable.

To the discharge of the plastic through the discharge nozzle 16 to interrupt, the metering valves 36 closed and the drive of the metering piston 36 stopped. The filling valves 50 stay closed. Because the metering valve 34 is a displacement-free working slide valve, leads to the closing of the metering valve 34 neither to an increase in pressure in the dosing chamber 30 still to a Nachschieben the respective component through the metering 32 into the mixing chamber 12 , If the discharge of the plastic continues, then the metering valve 34 opened again and the drive of the metering piston 36 started. Again, there is no pressure change in the metering chamber 30 and in the dosing channel 32 , An interruption of the discharge, z. B. to continue the discharge on another workpiece or at another point of the workpiece, thus leading neither to the end of the discharge nor the new start of the discharge to a fault or inaccuracy.

For compressible components, before closing the metering valve 34 a defined retraction of the dosing piston 36 done to the material in the mixing chamber 12 and the discharge nozzle 16 to relax and repress the material from the discharge nozzle 16 to prevent.

The metering devices for the various components A and B can optionally also be provided in duplicate. By switching the dosing a continuous operation is possible by during filling of the dosing 30 a metering device on the loading of the mixing chamber 12 is switched by the parallel, other metering device.

10

mixing head

12

mixing chamber

14

nozzle cover

16

discharge nozzle

18

mixer

20

wave

22

poetry

24

ball-bearing

26

Helical compression spring

28

drive motor

30

metering

32

metering

34

metering valve

36

dosing

38

poetry

40

cylinder

42

piston

44

pressure chamber

46

pressure chamber

48

filling channel

50

filling valve

52

spigot

54

cartridge

56

Plug

58

pressure cylinder

60

sealing piston

Claims (7)

Device for mixing and applying reactive plastics, with a mixing head ( 10 ), with one in the mixing head ( 10 ) formed mixing chamber ( 12 ), with one in the mixing chamber ( 12 ) arranged, motor-driven rotary mixer ( 18 ), with an axial to the mixing chamber ( 12 ) subsequent discharge nozzle ( 16 ) and with at least two metering devices for the plastic components (A, B) to be mixed, the metering devices each having a cylindrical metering chamber ( 30 ), an axial alignment with the metering chamber ( 30 ) subsequent dosing channel ( 32 ), which enters the mixing chamber ( 12 ) at an acute angle with respect to its central axis, one in the metering chamber ( 30 ) axially controlled displaceable dosing piston ( 36 ), one between the dosing chamber ( 30 ) and the dosing channel ( 32 ) used displacement-free operating metering valve ( 34 ), one side into the dosing chamber ( 30 ) filling channel ( 48 ) and one in the filling channel ( 48 ) inserted displacement-free filling valve ( 50 ), and wherein the metering devices completely into the mixing head ( 10 ) are integrated. Devices according to claim 1, characterized in that the drive motor ( 28 ) for the mixer ( 18 ) is a servo drive with adjustable controlled speed. Device according to claim 1, characterized in that the metering drive is a fluid-actuated cylinder-piston unit or an electric drive. Device according to one of the preceding claims, characterized in that the plastic components (A, B) of cartridges ( 54 ) are supplied to the filling channels ( 48 ) can be attached. Device according to claim 4, characterized in that the cartridges ( 54 ) on top of the mixing head ( 10 ) parallel to the axis of the mixing chamber ( 12 ), of the mixer ( 18 ) and the drive motor ( 28 ) are arranged. Device according to one of the preceding claims, characterized in that two metering devices are arranged diametrically opposite each other in a central axis of the mixing chamber ( 12 ) einschließenden level are arranged and that a plurality of devices parallel to this plane adjacent to each other are coupled to each other. Device according to one of the preceding claims, characterized characterized in that the metering devices each provided in duplicate and that the dosing devices of each pair are for one continuous operation alternately between filling operation and dosing can be switched.