DE102015112445A1 - Mixing head with a lubricating device for a cleaning piston - Google Patents

Abstract

The invention relates to a mixing head (1) for a reaction casting machine for producing reaction plastic, with a mixing chamber (2) within which a control piston (4) is arranged for regulating a component flow consisting of at least two components to be mixed, one to the mixing chamber (2 ) subsequent outlet channel (5), one in the outlet channel (5) retractable cleaning piston (6) which is inserted in at least one cleaning state, forming a radial gap (7) with the outlet channel (5) in the outlet channel (5), and a lubricating device (8) for lubricating the radial gap (7), wherein the lubricating device (8) has a lubricating channel (10), and the lubricating channel (10) in turn has an inlet region (3) which is oblique to a longitudinal axis of the outlet channel (5) in the outlet channel (5) opens, so that in the cleaning state, a lubricant is selectively conveyed into the radial gap (7) into it; a Reaktionsgießmaschine with such a mixing head (1); and a method for producing foam with such a mixing head (1).

Description

The invention relates to a mixing head (also referred to as Umlenkmischkopf) for a Reaktionsgießmaschine (eg, a polyurethane foaming), which is prepared for the production of reaction plastics, such as polyurethane foams, with a mixing chamber, within which a control piston for regulating a component flow (eg at least two to be mixed, reactive components) is arranged, an adjoining the mixing chamber outlet channel, an insertable into the outlet channel cleaning piston which is inserted in at least one cleaning state, forming a radial gap with the outlet channel in the outlet channel, and a lubricating device for lubricating the radial gap. A radial gap, which may also be referred to as a (circumferential) annular gap, in particular when the cleaning piston is arranged concentrically in the outlet channel, is also present when the cleaning piston rests in the outlet channel / outlet cylinder so that a liquid film of the lubricant still fits between them ,

Generic mixing heads are already known from the prior art. For example, the DE 195 15 039 A1 a device for mixing at least two chemically reactive plastic components under high pressure, with a cylindrical mixing chamber, in which the components are injected, wherein for discharging residual plastic mixture within the mixing chamber, a reversible piston is arranged. Also, the device has a cylindrical settling chamber / outlet chamber / outlet channel, which adjoins the mixing chamber and extends at an angle of preferably 90 ° to the longitudinal axis of the mixing chamber, wherein in the settling chamber, a reversible cleaning piston for discharging the reactive plastic mixture from the settling chamber is arranged , The cleaning piston has formed on its cylindrical surface recesses which are filled with spacer material and arranged helically on the lateral surface, so that when an axial movement of the cleaning piston this is rotated.

The EP 2 233 268 B1 further discloses a high pressure mixing apparatus suitable for mixing reactive chemical constituents and dispensing a resulting mixture.

It is therefore already known to use cleaning piston, clean / clear the outlet channel, which is often formed to a part of a bore / outlet bore, the other part of a spout. The cleaning itself is done by reciprocating this cleaning piston within the outlet channel, whereby excess material is pushed out of the outlet channel to the environment out. In order to convey as much material as possible out of the outlet channel and to free the outlet channel as completely as possible from excess material, the cleaning piston usually has a relatively narrow fit with its outer peripheral side opposite the inner peripheral side of the outlet channel. In particular, if it forms a layer of a plastic material, such as a polyurethane layer on the inside of the outlet channel, thereby the displacement of the cleaning piston is significantly more difficult. For the movement of the cleaning piston then usually very large axial forces are necessary. It follows, in turn, that the surfaces of the cleaning piston and the outlet bore are exposed to very high frictional forces, whereby the wear of the cleaning piston and the outlet channel is significantly increased.

Although there are also active lubrication, such as a pump, where the lubricating effect is good and the pollution is low, but then show other disadvantages, in particular, then existing filters are often changed. In the case of cascaded filters, however, the production costs of the lubricating unit are unfortunately very high.

When using known static lubrication, it has further been found to be disadvantageous that they are relatively expensive to operate and also often can not provide a sufficiently high lubrication performance of the radial gap over the entire operation. Especially with lubricating devices that move the radial piston through a lubrication sump, the lubricant can foam so much at long operating times that only a foam-lubricant mixture can be conveyed into the radial gap. The lubricant must therefore be replaced relatively frequently, whereby the operating costs of the mixing head increase significantly. Also, in these embodiments, the lubricant can easily escape again before it enters the radial gap, as a result of which the lubricant / lubricating fluid has to be regularly replenished and changed. Frequently, the known designs are also installation-dependent, being particularly affected in a vertical mounting position with upwardly directed / open outlet channel / outlet nozzle / directed / open outlet bushing, the lubricating effect. Often then additional pump circuits are necessary, which in turn require additional filters. The structure is in turn consuming.

It is therefore the object of the present invention to remedy these known from the prior art disadvantages and in particular to provide a mixing head available that should be cleanable as possible and used in various ways, whereby its life should not be adversely affected or even increased.

This is inventively achieved in that the lubrication device has a lubrication channel, and the lubrication channel in turn has a junction which obliquely / transversely, preferably orthogonally, to a longitudinal axis of the outlet channel (eg approximately an axial region of the outlet channel) opens into the outlet channel, so in the cleaning state, a lubricant targeted in the radial gap is conveyed / injectable is / is promoted / injected.

By such lubricant promotion, the friction forces are significantly reduced in the relative displacement between the cleaning piston and the outlet channel in an axial region within the outlet channel. Because the mutually sliding surfaces of the cleaning piston and the outlet channel are thereby selectively lubricated in the area within the outlet channel. As a result, lubrication is performed as effectively as possible within the areas of the mixing head affected by a material application. Also, the lubricant can thereby be preserved over the entire operating life of the mixing head in a suitable composition for an optimal lubrication line.

The lubrication line can also pass into a circumferential, that is to say surrounding the cleaning piston junction area.

In addition to an orthogonal confluence, angles of 15 ° to 165 °, in particular 30 ° and 60 ° at ± 5 ° deviation, are also suitable.

Further advantageous embodiments are claimed in the subclaims and explained in more detail below.

It is advantageous if the lubricating device uses one of the mixing chamber supplied components as a lubricant. As a result, the lubrication is implemented particularly effectively. There are thus no harmful to the foam to be produced materials supplied.

Most preferably, the mixing head is configured for a reaction casting machine (e.g., a polyurethane foaming machine) that produces a reaction plastic / foam material / foam such as a polyurethane material / PUR material / polyurethane foam / PUR foam. In this context, it is particularly advantageous if the lubricant is then formed as a first component of the PUR foam, which is anyway required for the manufacture of the material. Preferably, the lubricant is a polyol / polyhydric alcohol. This avoids that additional materials, which are not required for the production of the material, come into contact with the material to be produced.

If the cleaning piston has an evacuation contour in at least one axial region, which is widened in such a way that the radial gap is reduced in its radial extent, the cleaning piston is designed to be particularly effective for cleaning.

In this context, it is particularly advantageous if the junction region of the lubrication channel is arranged such that the lubricant is selectively conveyed into the radial gap at the axial height of the axial region in the cleaning state. Then the lubrication is used purposefully.

It is also advantageous if the lubricating device has a pump unit for conveying the lubricant. As a result, the lubricant can be conveyed into the radial gap formed between the cleaning piston and the outlet channel in the lubricating state particularly quickly. The lubrication is implemented as effectively as possible.

In this context, it is also advantageous if a pump unit for conveying the lubricant (viewed in its conveying direction) on the output side with the opening into the outlet channel lubrication channel and (again viewed in its conveying direction) is hydraulically connected on the input side with a lubricant supply. As a result, particularly short delivery paths are implemented and the lubricant can be conveyed into the radial gap as short a path as possible from a region / mixing head housing region arranged radially adjacent / outside the cleaning piston.

If the pump unit continues to be driven in such a way (preferably electronically and / or hydraulically) that the lubricant is pumped into the outlet channel at predetermined time intervals, the delivery of the lubricant is implemented particularly efficiently. Because outside of the cleaning state of the mixing head, such as in a mixed state / conveying state, in which the several, individual components of the material to be produced / foam material / foam through the mixing chamber into the outlet channel and then out of this again, No lubricant is needed. The lubricant can then be kept away from the cleaning piston to avoid air mixing of the lubricant as much as possible. In addition, no foam can penetrate into the lubricator when it is closed.

It is also expedient if the pumping unit has a pumping piston which, in a conveying state of the pumping unit (during its movement / displacement in a first (axial) displacement direction) contains a quantity of lubricant (determined / specified) contained in a pressure chamber of the pumping unit Lubrication channel) pushes in the outlet channel / -befördert / -pumpt. The pump unit is thus designed to be particularly powerful.

If the lubricant is introduced into the pressure chamber as a component of the foam to be produced, for example using a non-return valve, then the lubricant is particularly easy to prepare.

In this connection, it is furthermore advantageous if the pumping piston is arranged and configured in such a way that it draws lubricant into the pressure chamber in a suction state (ie during a movement / displacement in a second (axial) displacement direction opposite to the first (axial) displacement direction) / sucks. As a result, an intake state also effectively implemented by means of the pump piston. Also, the pump unit is therefore particularly simple in construction and inexpensive to produce.

If the pump piston continues to be switchable between the intake state and the delivery state by means of a hydraulic actuation device, a hydraulic connection which is already present in a reaction casting machine can be used to switch over the lubricating device / pumping unit. As a result, the operation of the lubrication device is particularly cost possible.

In addition, it is advantageous if the pump piston is stepped, i. at a cooperating with the hydraulic actuator axial broadening region has a larger diameter than at a projecting into the pressure chamber axial region. As a result, particularly high displacement forces for conveying the lubricant can be transmitted to the pump piston.

Is the pump piston also adjustable in its stroke, namely preferably by means of a stop screw, acting in a second displacement direction of the pump piston on this movement limiting, the pressure chamber and thus indirectly the stroke volume of lubricant to the respective application is adjustable. This makes it easy to adjust the lubrication performance to the respective operating condition.

In this context, it is also advantageous if a second channel portion of the outlet channel is formed by a connected to the first channel section / subsequent outlet nozzle. As a result, the mixing head is designed to be particularly functional in itself.

It is also advantageous if the lubrication channel is introduced directly in the mixing head housing area. As a result, the structure of the mixing head can be further simplified. It is also useful if the pump unit is attached / disposed on the mixing head housing area, whereby the conveying paths of the lubricant are kept as low as possible.

The cleaning piston advantageously protrudes into the outlet channel in such a way and is in its axial displacement / movement in the cleaning state within the first and the second channel portion movable so that it faces away in the cleaning state from one side of the first channel portion, which opens to the environment end is displaceable up to the opening end. This results in a particularly effective cleaning of the outlet channel. The cleaning piston can thus drive from the top to the very bottom.

It is also advantageous in this context if the lubrication channel so connects to the outlet channel and the lubricant is conveyed into the outlet channel, that in the cleaning state with the movement of the cleaning piston, the lubricant is conveyed into the axial region of the second channel section. As a result, lubrication of the second channel section is also implemented particularly effectively and the movement of the cleaning piston is further simplified.

Furthermore, the invention also relates to a reaction casting machine with a mounted mixing head according to one of the aforementioned embodiments.

Also, the invention relates to a method for producing foam / foam material, with a mixing head according to one of the aforementioned embodiments, wherein a lubricant in the cleaning state of the mixing head is selectively conveyed by a cleaning piston adjacent mixing head housing portion by means of the lubrication channel obliquely into the radial gap , As a result, the lubrication of the cleaning piston is carried out particularly effectively.

The invention will now be explained in more detail with reference to figures.

Show it:

1 a sectional view of a mixing head according to the invention according to an advantageous embodiment, wherein the mixing head is shown cut along the cleaning piston and along the mixing chamber, so that both the outlet channel within which the cleaning piston is movable, and the attachment of the lubricating device are visible, and

2 a sectional view according to the in 1 with "II-II" marked cutting line, so that in particular the internal structure of the pumping unit of the lubrication device and their connection to the lubrication channel are illustrated.

The figures are merely schematic in nature and are for the sole purpose of understanding the invention. The same elements are provided with the same reference numerals.

In 1 is a mixing head according to the invention 1 illustrated particularly vividly according to a preferred embodiment. The mixing head according to the invention 1 is designed as a Umlenkmischkopf. Consequently, the mixing head points 1 one in a housing 20 trained mixing chamber 2 which is designed to mix at least two different components together. The mixing head 1 is as a mixing head 1 a Reaktionsgießmaschine trained and used in operation. Consequently, the mixing head is 1 especially suitable for mixing at least two components which react with one another and to combine / mix them into a component stream.

A first component in a preferred application is a polyol / polyhydric alcohol, a second component is an isocyanate, which reacts both components in a mixed state to form a polyurethane foam.

In the axial direction of the mixing chamber 2 considered, is the mixing chamber 2 elongated, rectilinear and tube-like design and opens at one end into an outlet channel 5 , Inside the mixing chamber 2 is a control piston 4 in an example cylindrical mixing area 37 used, depending on the position of a component flow in the mixing chamber 2 mixed components / material components from the mixing chamber 2 out at high speed to the outlet channel 5 is conveyed into (open position of the Steuerkobens 4 ) or the components are prevented from mixing (closed position of the control head 4 ). The position of the spool 4 is in the usual way by means of a hydraulic control unit 39 at one of the outlet channel 5 facing away, widened piston head 40 adjustable. At the exit of the component stream from the mixing chamber 2 in the outlet channel 5 the component current changes direction. Because the outlet channel 5 is transverse in this embodiment, namely perpendicular, ie 90 ° to the mixing chamber 2 aligned. The component flow is thus at a right angle from the mixing chamber 2 out in the outlet channel 5 diverted.

The outlet channel 5 is in this embodiment by two channel sections 16 and 17 educated. A first channel section 16 closes directly to the mixing chamber 2 and is like the mixing chamber 2 an integral part of the case 20 namely, a mixing head housing portion 18 of the housing 20 , The first channel section 16 is formed directly as a bore with a constant over its length diameter / inner diameter. Also, the first channel section 16 within the mixing head housing area 18 educated. A second channel section 17 in the axial direction to the first channel section 16 immediately connected, is as a spout 19 educated. The spout 19 is towards the environment with its first section of the canal 16 opposite end 21 opened in this picture. The spout 19 is tubular shaped and therefore also referred to as outlet pipe. The spout 19 is by means of a positive, non-positive and / or cohesive connection firmly with the mixing head housing area 18 connected. The first and the second channel section 16 and 17 are arranged coaxially to each other and therefore also extend straight. The first and the second channel section 16 and 17 have a same inner diameter, whereby they together the outlet channel 5 form, which also has a constant inside diameter along its length.

In a conveying state / mixing state of the mixing head 1 / of the reaction casting machine becomes the material to be produced from the plurality of components through the mixing chamber 2 as well as the outlet channel 5 to the end opened to the environment 21 the outlet nozzle 19 promoted. In this delivery state is a cleaning piston 6 as explained below, for cleaning the outlet channel 5 is configured, positioned so that the component flow unhindered by the mixing chamber 2 over the outlet channel 5 to the end 21 can flow out. In a cleaning state of the mixing head 1 / the Reaktionsgießmaschine serves the cleaning piston 6 then again to clean the outlet channel 5 ,

Like also in 1 can be seen, is the cleaning piston 6 essentially as an oblong (along its longitudinal axis 42 ) extending rod, namely a solid rod, formed with a first end in the outlet channel 5 protrudes into it. The cleaning piston 6 is coaxial with the outlet channel 5 arranged (longitudinal axis 42 of the cleaning piston 6 is therefore congruent with the longitudinal axis of the outlet channel 5 ) and slidable in its axial direction in the housing 20 stored. A rod-shaped area 22 of the cleaning piston 6 has a constant over its length outer diameter, or may have a larger diameter in the front region. This rod-shaped area 22 protrudes directly into the outlet channel 5 into and is in this outlet channel 5 displaceable in the axial direction. Consequently, the outer diameter of the rod-shaped portion 22 chosen slightly smaller than the inner diameter of the outlet channel 5 , At a broadening area 23 of the cleaning piston 6 which is connected to the outlet channel 5 opposite end of the rod-shaped area 22 is attached, depending on switched position / switched state of the cleaning piston 6 a hydraulic pressure in an axial direction of the cleaning piston 6 at. This will make the widening area 23 in the cleaning state so hydraulically acted upon, that the cleaning piston 6 with the rod-shaped area 22 towards the end 21 the outlet nozzle 19 is moved / is and in the conveying state so hydraulically biased that the rod-shaped area 22 turn the mixing chamber 2 to the outlet channel 5 free.

The outer diameter of the rod-shaped area 22 , ie the design of the outer peripheral side 24 of the rod-shaped area 22 is on the inner diameter, ie the dimension of the inner peripheral side 25 the outlet channel 5 tuned so that the rod-shaped area 22 with the outlet channel 5 a sliding fit is received. In the cleaning state of the mixing head 1 becomes the cleaning piston 6 thereby in the axial direction to the end 21 postponed that into the outlet channel 5 protruding end face 26 of the rod-shaped area 22 on the inner circumference side 25 entrained during the conveying state residues of the component flow and finally at a fully extended position over the end 21 out to the environment out of the outlet channel 5 also promoted.

By the fact that the rod-shaped area 22 of the cleaning piston 6 as well as the outlet channel 5 adopt a clearance fit / push fit, forms a kind of gap, namely a radial gap 7 between the outer peripheral side 24 and the inner peripheral side 25 out. The on the inner circumference side 25 adhering material of the component flow is thereby at least partially in the cleaning state in the radial gap 7 between the outlet channel 5 and the cleaning flask 6 pushed in, causing the outer peripheral side 24 and the inner circumference side 25 in the axial displacement / movement of the cleaning piston 6 be subjected to increased friction. The radial gap 7 may be formed as an annular gap, that is, as a continuous gap in the circumferential direction or as in the circumferential direction, such as by a clearance contour, the cleaning piston 6 radially thickened outward, be formed interrupted gap. The evacuation contour is then in an axial region 9 of the cleaning piston 6 formed permanently (both in the cleaning state and in the conveying state / mixing state of the mixing head 1 ) axially in the outlet channel 5 is inserted. The evacuation contour is then preferably widened, for example in the form of a mushroom-shaped head, so that the radial gap 7 is at least partially reduced in its radial extent in this axial region of the evacuation contour. The radial gap 7 However, it is always dimensioned so that at least one film of lubricant radially between the inner peripheral side 25 and the outer peripheral side 24 is arranged. The junction area 3 of the lubrication channel 10 is then also arranged such that the lubricant targeted at the height of the axial region 9 in the cleaning state in the radial gap 7 is conveyed in.

To reduce the frictional forces between the cleaning piston 6 and the outlet channel 5 is a lubricating device according to the invention 8th at the mixing head 1 intended. The exact structure of this lubrication device 8th is particularly associated with 2 clear. The lubrication device 8th consists of a pump unit 11 and one in the mixing head housing area 18 introduced lubrication channel 10 who, as in 1 is particularly easy to see, substantially parallel to the mixing chamber 2 , also straight. The lubrication channel 10 flows into the outlet channel 5 in an axial area 9 the outlet channel 5 axially offset from the mouth of the mixing chamber 2 is arranged. The lubrication channel 10 has a junction area for this purpose 3 on, the obliquely / transversely, namely perpendicular to the outlet channel 5 runs and also obliquely / transversely, namely at an angle of approximately 90 ° in the axial region 9 / Outlet channel 5 opens. The lubrication channel 10 opens into the axial area 9 in both the conveying state and the cleaning state of the mixing head 1 / the reaction casting machine permanently through a part of the rod-shaped area 22 is covered.

Furthermore, spaced from the outlet channel 5 , is the pump unit 11 to the lubrication channel 10 connected. The pump unit 11 has one pump piston 12 on, which is mounted axially displaceable. As in 2 shown, the pump piston 12 furthermore a substantially rod-shaped first longitudinal section 30 on, in the axial direction in a pump housing 31 the pump unit 11 is guided. The pump housing 31 is fixed to the mixing head 1 connected and thus a solid component desselbigen, or may be outside of the mixing head housing. The pump housing 31 is about at the mixing head 1 namely at the mixing head housing area 18 screwed or otherwise firmly but removable again with the mixing head housing area 18 connected. The pump piston 12 , as in 2 To recognize particularly well, acts with one end face, namely a first end face 27 with a hydraulic pressure chamber 13 together. In 2 is the pump piston 12 shown in a first stop position in a first direction of displacement in which he largely / maximally in the pressure chamber 13 is moved into. In this first stop position is the pump piston 12 / the pump unit 11 in a basic position in which, for example, a lubricant already with a certain pressure in the pressure chamber 13 connected lubrication channel 10 is pressed in / is. In this first stop position is at the same time also in the pressure room 13 opening feed channel 28 a lubricant supply 38 via a check valve 29 with the pressure room 13 connected. The feed channel 28 is under slight pressure (return pressure of the component). This pressure also prevails in the pressure chamber 13 , Also, the lubrication channel 10 by conditioning the pump piston 12 on a closure body designed as a valve seat 36 from the pressure room 13 separated. This first stop position of the pump piston 12 is implemented at the end of the cleaning state, so that the lubricant already on the lubrication channel 10 obliquely, namely perpendicular / orthogonal to its longitudinal axis in the outlet channel 5 / in the radial gap 7 pressed in / conveyed / injected.

After a cleaning process has been carried out, ie again when the conveying state of the mixing head is implemented 1 , becomes the pump piston 12 then shifted in one of the first displacement direction opposite second direction of displacement, so that the first end 27 from that into the pressure room 13 opening area of the lubrication channel 10 moved away and thereby the volume of the pressure chamber 13 is enlarged. This creates a negative pressure within the pressure chamber 13 , whereupon the check valve 29 is opened. Through the opening check valve 29 is in this state of motion, namely the so-called intake of the pump unit 11 , Lubricant from the lubricant supply 38 in the pressure room 13 sucked in / sucked in. Is the pressure room 13 completely filled, is the pump piston 12 with a first end 27 opposite second end 41 turn on a stop screw 15 in plant (second stop position). Then the check valve closes 29 , When switching the mixing head 1 in the cleaning state, then turn the pump piston 12 moved in the opposite, first axial displacement direction and the check valve 29 safely pressed into its closed position, at the same time the lubricant through the lubrication channel 10 in the outlet channel 5 escapes. This state is also called the delivery state of the pump unit 11 referred to, which lasts until the pump piston 12 resumes his basic position.

In one at the first longitudinal section 30 subsequent, opposite the first longitudinal section 30 widened, second longitudinal section 32 is the pump piston 12 extended. Consequently, this second longitudinal section becomes 32 also referred to as widening section / area. This second longitudinal section 32 is in a opposite the pressure chamber 13 sealed control room 33 slidably mounted. The second longitudinal section 32 acts on the axial displacement of the pump piston 12 with a hydraulic actuator 14 together. This hydraulic actuator 14 has two hydraulic connections 34 and 35 on. A first hydraulic connection 34 opens in an axial area of the control room 33 in the control room 33 so that he has the second longitudinal section 32 axially pressurized in the direction of the first displacement direction with hydraulic pressure. The second hydraulic connection 35 opens axially offset to the first hydraulic connection 34 in the control room 33 so that he has the second longitudinal section 32 pressurized with hydraulic pressure in the second direction of displacement. Depending on the operated hydraulic connection 34 . 35 with pressure medium, thereby becomes the pump piston 12 urged in the first or second direction of displacement and thus the intake or the delivery state of the pumping unit 11 implemented. Both the first hydraulic connection 34 as well as the second hydraulic connection 35 are connected to a hydraulic supply.

The stroke of the pump piston 12 and thereby the amount of lubricant to be delivered is by means of the stop screw 15 with one end face in the control room 33 protrudes into it, set. This stop screw 15 is in the pump housing 31 taken rotatable. Depending on their rotational position thus the axial stroke of the pump piston 12 and indirectly, the size of the pressure chamber 13 set. This is a lubrication device 8th implemented, which is a pump in the form of a pump unit / pump unit 11 that in the mixing head 1 is integrated, with a lubrication channel 10 such across the outlet channel 5 runs so that the forming radial gap 7 between the cleaning piston 6 and the outlet channel 5 depending on the position of the pump unit 11 supplied with lubricant. By building the pump unit 11 Lubricant is particularly easy at individual time intervals / time intervals, for example, after each shot / discharge process of the component flow, in the radial gap 7 be conveyed during the cleaning state.

In other words, is thus a lubrication device 8th constructed at regular intervals (eg after each shot of the reaction casting machine) a small amount of lubricant, preferably polyol, in the gap (radial gap 7 ) between the cleaning piston 6 and the outlet channel 5 / the outlet hole 16 pumps and so the sliding surfaces 24 . 25 lubricates. In the basic position of the pump unit 11 (first stop position) is the first hydraulic connection 34 under pressure, with the second hydraulic connection 35 relieved at the same time. This will be the closure body 36 in the connection area between the pressure chamber 13 and the lubrication channel 10 by means of the pump piston 12 locked. This fills the room / pressure room 13 over the check valve 29 with lubricant / polyol from the return bore / feed channel 28 of the mixing head 1 , When sucking the pump piston moves 12 back, causing the room / pressure room 13 simultaneously via the check valve 29 additionally fills. When pumping finally the pump piston 12 drove up, into the pressure room 13 into it, so that in the room 13 build up a pressure. Then the check valve closes 29 and polyol flows through the bore / lubrication channel 10 in the gap / radial gap 7 between the cleaning piston 6 and the outlet pipe / outlet channel 5 , The pump piston 12 can build up very high pressures due to the hydraulic filling (different diameters front and rear). The amount of pumping can with the stroke of the pump piston 12 to be adjusted (via the screw 15 ).

LIST OF REFERENCE NUMBERS

1

 mixing head

2

 mixing chamber

3

 confluence area

4

 spool

5

 outlet channel

6

 cleaning piston

7

 radial gap

8th

 lubricator

9

 axial

10

 lubrication channel

11

 pump unit

12

 pump piston

13

 pressure chamber

14

 actuator

15

 stop screw

16

 first channel section

17

 second channel section

18

 Mixing head housing area

19

 outlet connection

20

 casing

21

 The End

22

 rod-shaped area

23

 broadening range

24

 Outer peripheral side

25

 Inner circumferential side

26

 front

27

 first end

28

 feed

29

 check valve

30

 first longitudinal section

31

 pump housing

32

 second longitudinal section

33

 control room

34

 first hydraulic connection

35

 second hydraulic connection

36

 closure body

37

 mixing area

38

 lubricant feed

39

 Hydraulic control unit

40

 piston head

41

 second end

42

 clearance contour

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 19515039 A1 [0002]
• EP 2233268 B1 [0003]

Claims (10)

Mixing head ( 1 ) for a reaction casting machine for producing reaction plastic, with a mixing chamber ( 2 ) within which a control piston ( 4 ) is arranged to regulate a component flow consisting of at least two components to be mixed, one to the mixing chamber ( 2 ) subsequent outlet channel ( 5 ), one in the outlet channel ( 5 ) retractable cleaning piston ( 6 ), which in at least one cleaning state, forming a radial gap ( 7 ) with the outlet channel ( 5 ), into the outlet channel ( 5 ) is inserted, and a lubricating device ( 8th ) for lubricating the radial gap ( 7 ), characterized in that the lubricating device ( 8th ) a lubrication channel ( 10 ), and the lubrication channel ( 10 ) again a junction ( 3 ), which obliquely into the outlet channel ( 5 ), so that in the cleaning state, a lubricant targeted into the radial gap ( 7 ) is conveyed into it. Mixing head ( 1 ) according to claim 1, characterized in that the lubricating device ( 8th ) one of the mixing chamber ( 2 ) uses components supplied as lubricant. Mixing head ( 1 ) according to claim 1 or 2, characterized in that the cleaning piston ( 6 ) in at least one axial region ( 9 ) has a clearing contour which is formed widened such that the radial gap ( 7 ) is reduced in its radial extent. Mixing head ( 1 ) according to claim 3, characterized in that the junction area ( 3 ) of the lubrication channel ( 10 ) is arranged such that lubricant targeted at the axial height of the axial region ( 9 ) in the radial gap ( 7 ) is conveyed into it. Mixing head ( 1 ) according to one of claims 1 to 4, characterized in that a pump unit ( 11 ) for conveying the lubricant on the output side into the outlet channel ( 5 ) discharging lubrication channel ( 10 ) and on the input side with a lubricant supply ( 38 ) is hydraulically connected. Mixing head ( 1 ) according to claim 5, characterized in that the pump unit ( 11 ) is controlled in such a way / electronically and / or hydraulically controlled that the lubricant at predetermined time intervals in the outlet channel ( 5 ) is conveyed into it. Mixing head ( 1 ) according to claim 5 or 6, characterized in that the pump unit ( 11 ) a pump piston ( 12 ), which in a conveying state of the pump unit ( 11 ) one in a pressure room ( 13 ) amount of lubricant in the outlet channel ( 5 ). Mixing head ( 1 ) according to claim 7, characterized in that the pump piston ( 12 ) is arranged and configured such that it is in an intake state of the pump unit ( 11 ) Lubricant in the pressure chamber ( 13 ). Reaction casting machine with a mixing head ( 1 ) according to one of claims 1 to 8. Method for producing foam with a mixing head ( 1 ) according to one of claims 1 to 8, wherein a lubricant in the cleaning state of the mixing head ( 1 ) targeted by a cleaning piston ( 6 ) adjacent mixing head housing area ( 18 ) by means of the lubrication channel ( 10 ) obliquely into the radial gap ( 7 ) is conveyed into it.

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