EP3495036B1 - Mixer insert for static mixer, static mixer and method of manufacturing - Google Patents

Description

The invention relates to a one-piece (static) mixer insert according to the preamble of claim 1 for a static mixer, comprising a first mixing element with a plurality of intersecting first webs (extending along the longitudinal center axis and arranged at an angle thereto) and at least one along a longitudinal axis second mixing element adjacent to the first mixing element and rotated by a twisting angle, in particular of 90°, relative to the first mixing element about the longitudinal axis, in particular identical, with a plurality of intersecting second webs (extending along the longitudinal central axis and arranged at an angle thereto), wherein the first webs have first web ends facing the second mixing element and the second webs have first web ends facing the first mixing element and wherein a part of the first and second web ends are distributed over the outer circumference of the mixer insert. The feature of the distributed arrangement of the first and second web ends over the outer circumference of the mixer insert means that these first and second webs or their web ends would end on the outer circumference, ie not in the interior of the mixer insert, without the connecting sections provided according to the invention to be explained later. The first web ends facing the second mixing element are arranged between a first crossing plane, in which the first webs intersect, and the second mixing element. Analogously, the second web ends are arranged between a second crossing plane, in which the second webs intersect, and the first mixing element. The webs are preferably support sections of the mixing elements which extend in a straight line, at an angle to and along the longitudinal central axis. Each mixing element has two groups of preferably parallel webs, where the two groups or the webs of the two groups intersect. The two groups of webs are preferably arranged in such a way that a web of the other group is accommodated perpendicularly to the longitudinal axis between each two webs of one group. At least one of the two groups has at least two webs which are spaced apart perpendicularly to the longitudinal axis, with a web of the other group being arranged between the webs. Each mixing element preferably comprises between three and twenty, preferably between four and twelve, ribs which are distributed over the two groups and are arranged next to one another perpendicularly to the longitudinal axis. More preferably, the first and at least the second mixing element have the same number and/or arrangement of fins.

Furthermore, the invention relates to a static mixer according to claim 10, comprising at least one, preferably exclusively one, mixer insert according to the invention. The mixer insert is arranged in a preferably tubular or line-shaped surrounding housing, which is preferably formed by the inner circumference of a fluid line of a device, in particular an industrial production device, very particularly preferably a spraying device.

Furthermore, the invention relates to a method for producing such a mixer insert according to the preamble of claim 11.

In the CH642564A1 describes a basic technology for static mixers with a so-called X-grid structure. The known mixer insert is arranged inside a tubular container and comprises a plurality of individual mixing elements arranged one behind the other along a longitudinal axis of the mixer element, each of which comprises a plurality of intersecting webs. In the known mixer insert, the mixing elements are alternately 90° relative to the longitudinal axis arranged twisted to each other. The well-known mixer insert or its individual mixing elements can only be produced in a complex metal casting process, with the mold being destroyed. In addition, filling the tubular housing with individual mixing elements to form the mixer insert is time-consuming. It has also become known to weld the individual mixing elements together at certain points to form a one-piece mixer insert.

Various methods have become known for producing the aforementioned X-grid geometry more cost-effectively from plastic. Only as an example is on the EP 2 001 580 B1 referred.

The applicant himself has described a mixer insert that is optimized in terms of production technology and consists of two plastic injection-molded parts that can be pushed into one another perpendicularly to form the mixer insert. Such a mixer insert is in the WO 2017/097860 A1 disclosed. However, the known mixer insert is only suitable to a limited extent or not at all for high pressures such as occur, for example, in supply lines for molten thermoplastic material in plastic injection molding devices, nor for high temperatures, which also occur in the aforementioned application.

The documents are also available for the technological background DE 10 2015 121 351 A1 of the applicant and the documents CH 706 732 A2 and EP 3 034 159 famous. DE 10 2015 121 351 A1 discloses a one-piece mixer insert according to the preamble of claim 1.

Proceeding from the aforementioned prior art, the invention is based on the object of specifying a one-piece and cost-effective mixer insert for static mixers which can be made simply and cost-effectively from materials that are stable under pressure and temperature, in particular metal or ceramic can be manufactured. Furthermore, the task consists in specifying a static mixer with such a mixer insert and an optimized production method for the production of such a mixer insert.

With regard to the one-piece mixer insert, this object is achieved with the features of claim 1, i.e. in the case of a generic mixer insert, in that each of the first web ends of the first mixing element, which are distributed over the outer circumference of the mixer insert, is materially connected via a connecting section to a connection section, in particular one that is spatially closest to the the outer circumference of the mixer insert is connected to the second web ends of the axially adjacent second mixing element which are arranged in a distributed manner. In other words, each first web end facing the second mixer insert and arranged on the outer circumference of the mixer insert transitions in one piece or monolithically via a respective connection section, in particular designed as a connecting web, into one of the second web ends of the second mixing element, facing the first mixing element and arranged on the outer circumference. As a result, the first web ends of the first mixing element, which are distributed over the outer circumference, support an associated second web end via the respective connection section formed monolithically with a respective first web end, so that a layered, monolithic production of the mixer insert, in particular in a 3D printing process or in a generative process , very particularly preferably in a powder bed process, even more preferably in a laser sintering process is possible. A complex casting technique that was previously used and the destruction of the casting mold for demolding purposes is therefore no longer necessary. At the same time, the mixing element according to the invention can be made of pressure- and temperature-stable materials, in particular metal or ceramics, which is preferred, so that a pressure- and temperature-stable, monolithic mixer insert has at least two, preferably only two or only three axially adjacent webs that each have intersecting webs Mixing elements results. Prefers is when the connecting sections connecting the respective first and second web ends distributed over the outer circumference, in particular in the form of connecting webs, extend both at an angle to the longitudinal extent of the respectively assigned first web and at an angle to the longitudinal extent of the respectively assigned second web. In other words, it is preferred if the connecting sections each span an angle (not equal to 180°) with the two webs connected via the respective connecting section.

With regard to the static mixer, the object is achieved with the features of claim 10, i.e. in a generic static mixer through the use of at least one, preferably exclusively one mixer insert designed according to the concept of the invention, which to complete its mixer functionality in a tubular, for example a Fluid line formed surrounding housing is added to an inlet and an outlet axially spaced therefrom, wherein the inner diameter of the surrounding housing corresponds to the outer circumference of the mixer insert, possibly plus a (particularly small) game.

With regard to the method, the object is achieved with the features of claim 11, i.e. in a generic method in that the mixer insert is built up monolithically, in layers by means of layers adjacent along the longitudinal axis and extending perpendicularly to the longitudinal axis in a generative process or in a 3D printing process The first mixing element is first built up in layers with its first web ends distributed over the outer circumference of the mixer insert and then to the first web ends of the first mixing element distributed over the outer circumference Connecting web formed connecting section is connected in perspective (i.e. built up in layers) and that a second web or its second web end of the second mixing element is connected in layers to each connecting section, wherein the second mixing element is also built up in layers after the first mixing element, so that a one-piece , monolithic mixer insert results with at least two mixing elements twisted about the longitudinal axis and the mixing elements are monolithically designed or connected to one another at their web ends which are distributed over the outer circumference and face one another via a connecting web.

Advantageous developments of the invention are specified in the dependent claims.

In order to avoid repetition, features disclosed according to the device should also apply and be claimable as according to the method. Likewise, features disclosed according to the method should also apply and be claimable as disclosed according to the device.

The invention is based on the idea of designing the mixer insert in such a way that it can be manufactured from metal or ceramic using a 3D printing process or alternatively a generative process, such as a powder bed process, very particularly preferably a laser sintering process, preferably without the need to remove support material again or use support structures to be removed again or to have to build. According to the invention, this is achieved in that the first web ends of the first intersecting webs of the first mixing element, which are distributed over the outer circumference of the mixer insert and face the second mixing element, and the second web ends of the second intersecting webs of the second intersecting webs, which are distributed over the outer circumference and face the first mixing element second mixing element are designed or connected monolithically or are via a respective connecting section made of the mixer insert material, in particular metal or ceramic. The connecting sections, in particular the connecting webs, preferably each run at an angle both to the longitudinal extent of the respective first and the respective second web monolithically connected or formed to one another via the respective connecting section. An embodiment is very particularly preferred in which there are no free web ends in the transition area between the first mixing element and the second mixing element, but rather these transition into the respective adjacent mixing element via corresponding connecting sections. The monolithic connection of the web ends of the first and second mixing element, which are distributed over the outer circumference and face the other mixing element, not only enables a revolutionary production of the mixer insert made of metal or ceramic in a 3D printing process or in a generative process, but also pressure stability of the resulting mixer insert is significantly increased in comparison to known mixer inserts with the respective free web ends facing the adjacent mixing element, since axial forces can be supported or absorbed via the intermediate elements.

An embodiment of the static mixer insert in which the is not distributed over the outer circumference is very particularly preferred arranged, first and second web ends, so those web ends in the interior of the mixer insert are also not designed as free ends, but monolithically or materially connected to the respective axially adjacent mixing element are formed or connected. In a further development of the invention, this is preferably achieved in that the first and second web ends, which are not distributed over the outer circumference, meet along a transverse axis extending perpendicularly to the longitudinal axis and are connected to one another materially there, in particular perpendicularly to the longitudinal axis. Optionally and preferably, this transverse axis is completed or terminated at both ends by first and/or second webs arranged on the outer circumference and/or connecting sections (in particular connecting webs) connecting them.

In the case of the classic X-grid geometry, each mixing element has two crossing planes spaced apart along the longitudinal axis, in which crosspieces of the mixing element intersect.

In a further development of the invention, this is not the case with a mixer insert according to the invention, but the mixing elements of the mixer insert according to the invention are expediently designed in such a way that they each have only a single crossing plane extending perpendicularly to the longitudinal center axis in which the webs of the respective mixing element intersect. The feature 'intersect' means that the webs not only meet in a crossing plane, but also extend beyond the crossing plane. As a result, an embodiment of the mixing element can be realized which has free web ends at most in the area of the mixer insert ends, ie at the ends pointing away from one another, which point axially away from all adjacent mixing elements.

An embodiment of the mixer insert is particularly expedient in which the intersecting first webs and/or the intersecting second webs form an angle opening along the longitudinal axis of between 89° and 1°, preferably between 80° and 10°, even more preferably between 70 ° and 20 °, most preferably between 60 ° and 30 °, even more preferably between 59 ° and 53 °, most preferably spanning 56 °, in particular, which is preferred when the ratio between height and longitudinal extent of each of the mixer elements along the longitudinal central axis and the diameter of the respective mixer element should be one to one. The webs preferably each span an angle with the longitudinal central axis which corresponds to half of the above-mentioned angle between two intersecting webs.

In the classic X-grid geometry, each mixer element has intersecting webs that extend from an outer peripheral side of the associated mixing element to a diametrically opposite outer peripheral side of the mixing element. In a development of the invention, this is not the case here—this means that, according to a preferred embodiment, none of the first and second webs extends from an outer peripheral side of the associated mixing element to a diametrically opposite outer peripheral side of the mixing element.

An embodiment of the mixer insert is particularly expedient in which the length of the mixer insert is an even multiple of the outside diameter of the enveloping contour, ie the outside diameter of the mixer insert. It is preferred if the ratio of the length of each mixer insert to its diameter, measured perpendicularly to the longitudinal extent, is one to one. As already mentioned, one embodiment of the Mixer insert particularly preferred, in which all the second mixing element facing first web ends of the first webs of the first mixing element are materially connected to the second mixing element, in particular to the first mixing element facing second web ends of the second webs of the second mixing element. In principle, it is very particularly preferred if the (outer) enveloping contour of the mixer insert is in the form of a circular cylinder.

According to a preferred embodiment, it is provided that at least some of the webs, in particular at or in the region of the first and/or second web ends and/or the web ends of the second mixing element pointing away from the first mixing element, are provided with fluid conductor elevations monolithically formed with the respective webs , which taper, in particular in the shape of an arrow, along the longitudinal axis (perpendicular to it) against the direction of flow of fluid flowing through a finished mixer insert, in order to deflect or displace the fluid laterally, in order to prevent the fluid from flowing directly against a peripheral wall surrounding the mixer insert in a finished static mixer is pressed. As a result, dead zones and thus deposit effects in the area where the web ends adjoin the peripheral wall can be reduced, as can pressure losses.

According to the invention, the static mixer insert according to the invention can be produced monolithically, preferably from metal or ceramics, specifically in a 3D printing process or in a generative process, very particularly preferably in a powder bed process, even more preferably in a laser sintering process or alternative generative processes. It is essential that the mixer insert is built up in layers in the axial direction, ie in the direction of its longitudinal extension, with the layers perpendicular to the longitudinal axis build up or extend. In this case, the first mixing element is first built up in layers, specifically with its first web ends facing a later second mixing element, which then transition in layers or are connected to respective connecting sections, in particular connecting webs, to which the second web ends of the second mixing element to be built up in layers then directly adjoin. facing the first mixing element. The connecting sections remain in the mixer insert and therefore no longer have to be removed, which not only results in a mixer insert that is surprisingly simple to manufacture, but also in a mixer insert that is particularly pressure-resistant and, due to the choice of material, also temperature-stable.

Further advantageous configurations of the mixer insert that can be produced by means of a method according to the invention are disclosed in connection with the explanation of the features according to the device.

With at least one, preferably exclusively one, mixer insert according to the invention, which comprises a plurality of, in particular exclusively two or exclusively three, mixing elements, of which adjacent mixing elements are arranged rotated relative to one another by an angle of rotation, for example of 90° or less, about the longitudinal central axis Way form a static mixer in which the mixer insert is received in a surrounding housing. The static mixer is characterized in that the mixer insert is accommodated in a, in particular tubular, surrounding housing, which is preferably made of metal or ceramic and very particularly preferably by an industrial device, such as an injection molding device, or a fluid line or a fluid line provided therein Fluid line section is formed.

The static mixer according to the invention and/or the one-piece mixer insert according to the invention is suitable in particular, but not limited to this, for use in plastic injection molding machines for mixing thermoplastic, molten plastic to be injected in order to homogenize the temperature profile.

Further advantages, features and details of the invention result from the following description of preferred exemplary embodiments and from the drawings.

Fig. 1, 4 sowie Fig. 6 bis Fig. 9

unterschiedliche, teilweise perspektivische Ansichten eines nach dem Konzept der Erfindung ausgebildeten Mischereinsatzes, umfassend ausschließlich zwei axial benachbarte Mischelemente, deren Stege monolithisch über Verbindungsabschnitte miteinander verbunden sind,

Fig. 3

eine perspektivische Darstellung der die Mischelemente bzw. deren Stegenden monolithisch miteinander ausbildenden bzw. verbindenden Verbindungsabschnitte bzw. eine entsprechende Verbindungsabschnittsgeometrie, und

Fig. 2 und Fig. 5

zur besseren Nachvollziehbarkeit eine isolierte Darstellung der eigentlich monolithisch miteinander verbundenen Mischelemente ohne Verbindungsabschnitte.

These show in:

Fig. 1, 4 and Fig. 6 to Fig. 9

different, partially perspective views of a mixer insert designed according to the concept of the invention, comprising only two axially adjacent mixing elements whose webs are monolithically connected to one another via connecting sections,

3

a perspective representation of the connecting sections forming or connecting the mixing elements or their web ends monolithically to one another or a corresponding connecting section geometry, and

2 and 5

for better comprehensibility, an isolated representation of the actually monolithically connected mixing elements without connecting sections.

In the figures, the same elements and elements with the same function are identified by the same reference symbols.

The figures show a one-piece, monolithic (static) mixer insert 1, in this case made of metal, for forming a static mixer by arranging the mixer insert 1 in a tube or line-like surrounding housing, not shown. The mixer insert 1 has a circular-cylindrical (outer) enveloping contour. The mixer insert 1 comprises a first mixing element 2 at the bottom in the plane of the drawing and a second mixing element 3 which is adjacent axially along a longitudinal axis L. The two mixing elements 2, 3 are designed monolithically, avoiding free web ends or merge into one another via connecting sections 4, which are only for reasons of the better comprehensibility or identifiability in the figures are represented graphically or in different colors - in reality, these look from their outer surface or composition like the actual mixing elements 2, 3, i.e. merge seamlessly into them.

The first mixing element 2 has a plurality of first webs 6 which intersect in a single first crossing plane 5 and which extend along the longitudinal central axis L and are arranged at an angle to it or form an angle with it. In the exemplary embodiment shown, two intersecting first webs each span an angle α of 56° in the present case.

The first webs 6 are divided into two groups 7, 8 of webs, the first webs 6 of the groups 7, 8 being arranged perpendicularly to the longitudinal center axis L in alternation. The first webs 6 have the second mixing element 3 facing first web ends 9 which are arranged axially between the second mixing element 3 and the single first crossing plane 5 . The first web ends 9 are divided into a part of the first web ends 10 distributed over the outer circumference and a part of the inner first web ends 11.

The second mixing element 3 is constructed almost identically to the first mixing element 2 with the essential difference that the second mixing element 3 is arranged rotated by 90° about the longitudinal central axis L relative to the first mixing element 2 . The second mixing element 3 comprises a multiplicity of crossing second webs 12 which intersect in a single second crossing plane 13 . The second intersecting webs 12 also span an angle α oriented in the longitudinal axis L or opening along the longitudinal axis L of 56° in the exemplary embodiment. The second webs 12 are also divided into two groups 14, 15 of perpendicular to the longitudinal center axis L alternating second webs. The second webs 12 have the second web ends 16 facing the first mixing element 2, which are in turn divided into a part of second web elements 17 distributed over the outer circumference and a part of inner second web ends 18.

Out of 1 It can be seen that each of the first web ends 10 arranged distributed over the outer circumference is connected via a respective web-shaped connecting section 4 to an axially opposite (nearest) second web end of second web ends 17 arranged distributed over the outer circumference. The connecting sections 4 are designed like webs and run at an angle to the longitudinal extent of the respectively assigned first web 6 and the respectively assigned second web 12. The inner first and second web ends 11, 18 are also connected to one another via connecting sections, with the connecting sections for connecting the inner web ends 11 , 18 how out 3 results, extend along a perpendicular to the longitudinal axis L extending transverse axis Q.

It can thus be seen in the figures that there are no free web ends in the transition area between the first and second mixing element 2, 3, but these continue via a respective connecting section in the axially opposite or closest web end of the axially adjacent mixing element.

For reasons of clarity, only in the 8 , 9 an axial flow direction (flow direction) extending along the longitudinal axis L of at least one fluid to be mixed by means of a finished static mixer which comprises a mixer insert 1 according to the invention is shown or drawn in with the arrow F. It can be seen that the first webs in the area of their first web ends 10 distributed over the outer circumference have or form raised fluid conductor elevations 19 in the radial direction, which taper against the fluid flow direction F and thus deflect the oncoming fluid laterally, which means that a direct impact of the at least prevent fluid from flowing onto or against a peripheral wall surrounding the mixer insert 1 in a finished static mixer.

Such fluid guide elevations 19 are also found again at web ends 20 of the second webs 12 facing away from the first mixing element 2 or that part of these web ends 20 which end on the outer circumference.

Of course, the mixer insert 1 shown can also be manufactured without the fluid conductor elevations 19 .

The mixer insert 1 shown in the figures and designed according to the concept of the invention is built up in layers in the axial direction, in particular by laser sintering, starting in the plane of the drawing at the bottom, so that the mixer insert 1 during manufacture is layered along the longitudinal axis L, here in the plane of the drawing from below grows upwards. The first web ends 9 are each connected to a connecting section 4, which then merges into a next, assigned second web end 16. It is essential that at least all of the first web ends 10 distributed over the outer circumference are each connected via a connecting section 4 to an assigned, in particular spatially next to the outer circumference arranged distributed over the second web end 17 are connected or monolithic. As explained, all free, first and second web ends 9, 16 are connected to one another here, i.e. also the inner first web ends 11 and the inner second web ends 18.

Reference sign

1

mixer insert

2

first mixing element

3

second mixing element

4

connection section

5

first crossing level

6

first webs

7

first group of first webs

8th

second group of first webs

9

first web ends

10

Part of first webs distributed over the outer circumference of the mixer insert

11

Part of the first webs arranged inside

12

second webs

13

second crossing level

14

first group of second webs

15

second group of second webs

16

second web ends

17

Part of second webs distributed over the outer circumference of the mixer insert

18

Part of the second webs arranged inside

19

fluid conductor elevations

20

web ends of the second webs facing away from the first mixing element

L

longitudinal axis

Q

transverse axis

a

Angle between crossing webs

f

Flow direction (flow direction) of fluid

Claims (11)

1. A one-piece mixer insert (1) for a static mixer, the mixer insert (1) comprising a first mixing element (2) having a plurality of crossing first rods (6) and the mixer insert (1) comprising at least one second mixing element (3) adjacent to the first mixing element (2) along a longitudinal axis (L), twisted around the longitudinal axis (L) by a twist angle, in particular of 90°, relative to the first mixing element (2) and having several crossing second rods (12), the first rods (6) having first rod ends (9) facing the second mixing element (3) and the second rods (12) having first rod ends (9) facing the first mixing element (2) and part of the first and second rod ends (10, 17) being distributed over the outer circumference of the mixer insert (1),
   characterized in that
   each of the first rod ends (10) distributed over the outer circumference of the mixer insert (1) is connected to one of the second rod ends (17) distributed over the outer circumference of the mixer insert (1) in a material-bonded manner via a connection portion (4), in particular a connection web.
2. The mixer insert (1) according to claim 1,
   characterized in that
   the mixer insert (1) is produced as a monolithic component, in particular made of metal or ceramic, in a 3D printing process or in a generative process, in particular in a powder bed process, preferably in a laser sintering process, or in a 3D printing process.
3. The mixer insert according to claim 1 or 2,
   characterized in that
   the first and second rod ends (11, 18) which are not distributed over the outer circumference are connected to one another in a material-bonded manner, in particular together with part of the first and second rod ends (10, 17) distributed over the outer circumference, via a connection portion which extends perpendicular to the longitudinal axis (L), preferably from one outer circumference side to a diametrically opposite outer circumference side of the mixer insert (1).
4. The mixer insert according to any one of the preceding claims,
   characterized in that
   the first rods (6) cross exclusively in a first crossing plane (5) which extends perpendicular to the longitudinal axis (L) and the second rods (12) cross exclusively in a second crossing plane (13) which extends perpendicular to the longitudinal axis (L) and which is parallel to the first crossing plane (5).
5. The mixer insert according to any one of the preceding claims,
   characterized in that
   the crossing first rods (6) and/or the crossing second rods (12) form an angle (α) between 89° and 1°, preferably between 80° and 10°, even more preferably between 70° and 20°, particularly preferably between 60° and 30°, even more preferably between 59° and 53°, more preferably of 56°, which opens along the longitudinal axis (L).
6. The mixer insert according to any one of the preceding claims,
   characterized in that
   none of the first and second rods (6, 12) extends from an outer circumference side of the corresponding mixing element (2, 3) to a diametrically opposite outer circumference side of the mixing element (2, 3).
7. The mixer insert according to any one of the preceding claims,
   characterized in that
   the longitudinal extension of the mixer insert (1) is an even multiple of the shell contour outer diameter of the mixer insert (1).
8. The mixer insert according to any one of the preceding claims,
   characterized in that
   all first rod ends (9) of the first rods (6) of the first mixing element (2) facing the second mixing element (3) are connected to the second mixing element (3) in a material-bonded manner.
9. The mixer insert according to any one of the preceding claims,
   characterized in that
   fluid-guiding protrusions for displacing fluid which extend along the longitudinal axis (L) and which taper perpendicular thereto, preferably in an arrow-like manner, are formed at least on part of the first and/or second rod ends (9, 16) and/or at least on part of the rod ends (20) of the second rods (12) facing away from the first mixing element.
10. A static mixer having a mixer insert (1) according to any one of the preceding claims disposed in a housing having an inlet and an outlet axially spaced apart therefrom.
11. A method for producing a mixer insert (1) according to any one of claims 1 to 9,
    characterized in that
    the mixer insert (1) is formed monolithically, in layers which are adjacent along the longitudinal axis (L) and which extend perpendicular to the longitudinal axis (L), in a 3D printing process or in a generative process, in particular in a powder bed process, preferably in a laser sintering process, wherein the first mixing element (2) comprising its first rod ends (10) distributed over the outer circumference of the mixer insert (1) is first formed in layers and a connection portion (4), in particular a connection web, is then connected in layers to each of the first rod ends (10) of the first mixing element (2) distributed over the outer circumference and in that a second rod (17) of the second mixing element (3) is connected in layers to each connection portion (4).

Images