DIE COMPRISING METAL PRINTED PARTS FOR THE EXTRUSION OF MOULDED BODIES

Abstract

The invention relates to a die (10) for the extrusion of catalyst molding, catalyst support molding, or adsorbent molding (60) in flow direction (32) of an extrudable composition from an entry side (12) to a discharge side (14) of the die comprising a shell (56) and comprising one or more channel-formers (18) which are displacers of the extrudable composition and which extend in flow direction of the extrudable composition, wherein the channel-formers (18) have been metal-printed.

It is preferable that this is free from cavities for receiving extrudable composition which extend at right angles to the flow direction (32) of the extrudable composition, and that this is free from connections running at right angles from channel-formers (18) to the interior side wall (22) of the die (10).

The invention further relates to a process for the production, by means of 3D metal printing, of a metal-printed die (10) for the extrusion of catalyst moldings/support moldings (60).

Claims

1.-15. (canceled)

16. A die for the extrusion of catalyst moldings, catalyst-support moldings or adsorbent moldings in flow direction of an extrudable composition from an entry side to a discharge side of the die comprising a shell and comprising one or more channel-formers which are displacers of the extrudable composition and which extend in flow direction of the extrudable composition, where the channel-formers which are displacers of the extrudable composition have been secured by way of one or more connecting webs on an interior side wall of the die, wherein the die is free from connections running at right angles from channel-formers to the interior side wall of the die and is free from cavities for receiving extrudable composition which extend at right angles to the flow direction of the extrudable composition, and wherein the channel-formers have been metal-printed.

17. The die according to claim 16, wherein the channel-formers have a connection to one another.

18. The die according to claim 16, wherein some of the channel-formers have connection to one another.

19. The die according to claim 16, wherein, for the extrusion of catalyst moldings or of support moldings, this has 2 to 20 channel-formers parallel to the flow direction of the extrudable composition.

20. The die according to claim 16, wherein the channel-formers extending in flow direction of the extrudable composition have first and second diameters different from one another, and have a circular or polygonal shape.

21. The die according to claim 16, wherein it is composed of a metal-printed insert in which the channel-formers and connecting webs are present, and of the shell.

22. The die according to claim 21, wherein the shell has been manufactured from a plastics material.

23. The die according to claim 21, wherein the shell has been manufactured from a Teflon.

24. The die according to claim 16, wherein the shell and the channel-formers connected by way of connecting webs to the interior side wall thereof have been manufactured from a single piece and have been metal-printed.

25. The die according to claim 24, wherein the shell has an exterior jacket which serves to retain the die.

26. The die according to claim 25, wherein the exterior jacket has been manufactured from a plastics material.

27. The die according to claim 25, wherein the exterior jacket has been manufactured from a Teflon.

28. A metal-printed insert with channel-formers and with connecting webs for the production of a die according to claim 21.

29. A process for production, by means of 3D metal printing of the metal-printed die according to claim 16 for the production of a die for the extrusion of catalyst molding, catalyst support molding, or adsorbent molding, with at least the following process steps: a) application of a metal powder in successive layers, b) before application of a subsequent metal powder layer, irradiation of the preceding powder layer with a laser in a prescribed region, c) melting of the metal powder in the prescribed region over the entire layer thickness of the metal powder layer of said region by the energy introduced in step b), and formation of a compact metal layer bonded to the compact metal layer located thereunder, d) by alternating application and melting of a plurality of powder layers on top of one another, production of the metal-printed die or of the metal-printed insert as combination of molten layers composed of the metal powder layers applied on top of one another.

30. A process for production, by means of 3D metal printing of the metal-printed insert according to claim 21 for the production of a die for the extrusion of catalyst molding, catalyst support molding, or adsorbent molding, with at least the following process steps: a) application of a metal powder in successive layers, b) before application of a subsequent metal powder layer, irradiation of the preceding powder layer with a laser in a prescribed region, c) melting of the metal powder in the prescribed region over the entire layer thickness of the metal powder layer of said region by the energy introduced in step b), and formation of a compact metal layer bonded to the compact metal layer located thereunder, d) by alternating application and melting of a plurality of powder layers on top of one another, production of the metal-printed die or of the metal-printed insert as combination of molten layers composed of the metal powder layers applied on top of one another.

31. The process according to claim 29, which further comprises the additional steps of: e) experimental investigation of the die in respect of the flow behavior of the extruded composition in the die, f) repeated conduct of the steps a) to e) and optionally f), where the structure of the die is altered.

32. A process for the development of new catalyst molding, catalyst support molding or absorbent molding produced by means of extrusion with the steps of: (i) production of a plurality of different dies with different structure by the process according to claim 27, where the dies can be produced simultaneously or in succession, (ii) extrusion of various moldings with the various dies, (iii) experimental investigation of the various moldings with regard to their physical and chemical properties in a bed, (iv) optionally repetition of the steps (i) to (iii), where the design of the dies is altered.

33. The process according to claim 32, wherein the moldings are investigated experimentally in respect of their pressure loss and/or of their catalytic activity in a bed.

Description

[0054] The figures depict examples and embodiments of the invention, which are explained in more detail in the description below, in which:

[0055] FIG. 1 shows a die of the prior art in longitudinal section

[0056] FIG. 2 shows a die of the prior art in plan view of the entry side

[0057] FIG. 3 shows a first embodiment of a die of the invention in longitudinal section

[0058] FIG. 4 shows a first variant of the embodiment as in FIG. 1 in longitudinal section

[0059] FIG. 5 shows a second variant of the embodiment as in FIG. 1 in longitudinal section

[0060] FIG. 6 shows a metal-printed insert as in the second variant depicted in FIG. 3 in longitudinal section

[0061] FIG. 7 shows a second embodiment of a die of the invention in plan view of the entrance side

[0062] FIG. 8 shows the second embodiment as in FIG. 7 in plan view of the discharge side

[0063] FIG. 9 shows the second embodiment as in FIG. 7 in 3D depiction of the discharge side

[0064] FIG. 10 shows the second embodiment as in FIG. 7 in a sectional 3D depiction

[0065] FIG. 11 shows the second embodiment as in FIG. 7 in a 3D depiction of the entry side

[0066] FIG. 12 shows a third embodiment of a die of the invention in longitudinal section

[0067] FIG. 13 shows the third embodiment as in FIG. 12 in plan view of the entry side

[0068] FIG. 14 shows the third embodiment as in FIG. 12 in plan view of the discharge side

[0069] FIG. 15 shows the third embodiment as in FIG. 12 in a 3D depiction of the discharge side

[0070] FIG. 16 shows the third embodiment as in FIG. 12 in a sectional 3D depiction

[0071] FIG. 17 shows the third embodiment as in FIG. 12 in a sectional 3D depiction of the entry side

[0072] FIG. 18 shows a fourth embodiment of a die of the invention in longitudinal section,

[0073] FIG. 19 shows the fourth embodiment as in FIG. 18 in plan view of the entry side

[0074] FIG. 20 shows the fourth embodiment as in FIG. 18 in plan view of the discharge side

[0075] FIG. 21 shows the fourth embodiment as in FIG. 18 in a 3D depiction of the discharge side

[0076] FIG. 22 shows the fourth embodiment as in FIG. 18 in a sectional 3D depiction

[0077] FIG. 23 shows the fourth embodiment as in FIG. 18 in a 3D depiction of the entry side

[0078] FIG. 24 shows a plan view of a molding extruded with a die as in the second or fourth embodiment

[0079] FIG. 25 shows a plan view of the molding extruded with a die as in the third embodiment

[0080] FIG. 26 shows a photograph of the molding extruded with a die as in the fourth embodiment

[0081] FIG. 27 shows a photograph of the molding extruded with a die as in the third embodiment

[0082] FIGS. 1 and 2 show a die of the prior art. An extrudable composition flows here in flow direction (32) from an entry side (12) to a discharge side (14) of the die. The die comprises a shell (56), the internal side (22) of which has a diameter constriction (38), with a plurality of channel-formers (18) which are displacers of the extrudable composition and extend in flow direction of the extrudable composition. The displacers (18) are formed by metal pins inserted into a metal plate (20) with apertures (42). The metal plate (20) is connected at right angles to the internal side (22) of the shell (56). Below the metal plate (20) there are therefore cavities (62) for receiving extrudable composition which extend at right angles to the flow direction (32) of the extrudable composition. The shell (56) has a jacket (58) made of plastic with an external side (24) with diameter step (44) which serves to retain the die (10).

[0083] In the first embodiment, depicted in FIG. 3, of a die of the invention, an extrudable composition flows in flow direction (32) from an entry side (12) to a discharge side (14) of the die. The die comprises a shell (56), the internal side (22) of which has a diameter constriction (38), with a plurality of channel-formers (18), which are displacers of the extrudable composition and extend in flow direction of the extrudable composition. Channel-formers (18) here with a smaller first diameter (26) form a ring surrounding a central channel-former (18) with a greater second diameter (28). There are connections (30) between some of the channel-formers (18), and the channel-formers are connected by way of connecting webs (36) to the interior side wall (22) of the shell (56). The ends (40) of the channel-formers (18) here lie within the plane of the discharge aperture (50). Said connecting webs (36) run at an angle of less than 90° to the interior side wall (22) to the channel-formers (18). The die comprising shell (56), connecting webs (36) and channel-formers (18) has been manufactured from a single piece and produced by 3D metal printing. The shell (56) has a jacket (58) made of plastic with an external side (24) with diameter step (44) which serves to retain the die (10). The dimensioning of the jacket is such that it can be fitted into a die plate intended to receive a plurality of individual dies (10).

[0084] In the first variant, depicted in FIG. 4, of the embodiment depicted in FIG. 3, the jacket (58) made of plastic is omitted. The dimensioning of the entire die is such that it can be fitted into a cutout of a die plate.

[0085] In the second variant, shown in FIG. 5, of the embodiment depicted in FIG. 3, only an insert (34) comprising connecting webs (36) and channel-formers (18) has been metal-printed. The shell (56) with diameter step (44) and with interior side wall (22) of the die (10) has been manufactured from plastic. The insert (34) is fitted into the shell (56) and has the frictional and interlocking connection thereto.

[0086] In FIG. 6, the insert (34) comprising connecting webs (36) and channel-formers (18) for the production of a die as in FIG. 5 is shown separately.

[0087] FIGS. 7 to 11 show various depictions of a second embodiment of the die of the invention. Arranged around a central channel-former (18, 54) with hexagonal shape (54) in this embodiment there are channel-formers (18, 52) of rounded shape with a smaller first diameter (26) in an exterior circle and channel-formers (18, 52) of rounded shape with a greater second diameter (28) in a concentric interior circle. The central channel-former (18, 54) has connection by way of three connecting webs (36) to the interior side wall (22) of the shell (56) of the die (10). The exterior and interior channel-formers (18, 52) have connection by way of a respective connecting web (36) to the interior side wall (22) of the die (10). The die has been manufactured from a single piece, and has a jacket (58) made of plastic with a diameter step (44).

[0088] FIGS. 12 to 17 show various depictions of a third embodiment of the die of the invention. In contrast to the second embodiment shown in FIGS. 7 to 11, this embodiment has four circular channel-formers (18) of equal size in a square arrangement, with ends (40) lying within the plane of the discharge aperture, thus giving a clover-leaf arrangement with the shaping (48) of the discharge aperture. Each of the four channel-formers has connection to a respective connecting web (36), these together forming a rib system (16).

[0089] FIGS. 18 to 23 show various depictions of a fourth embodiment of the die of the invention. Likewise arranged around a central channel-former (18) with hexagonal shape (26) in this embodiment there are channel-formers (18) of rounded shape with a smaller first diameter (28) in an exterior circle and channel-formers (18) of rounded shape with a greater second diameter (54) in a concentric interior circle. In this embodiment, in contrast to the second embodiment shown in FIGS. 7 to 11, all channel-formers (18) have connection to the central channel-former with hexagonal shape (54) and have connection by way of three connecting webs (36) in the manner of a rib system (16) to the interior side wall (22) of the die (10).

[0090] FIG. 24 shows a molding (60) extruded with a die of the third embodiment, with a molding shape (64) in the form of a clover leaf corresponding to the shape of the die aperture, and with walls (66) and circular channels (68) in clover-leaf arrangement.

[0091] FIG. 25 shows a molding (60) extruded with a die of the second or fourth embodiment, with a molding shape (64) corresponding to the shape of the die aperture, and with walls (66) and circular and, respectively, hexagonal channels (68).

[0092] Production of moldings by means of what is known as 3D metal powder laser printing is described by way of example in DE 19649865 C1.

[0093] The extrusion dies are produced by using a process for the production of a molding. Production of moldings by means of what is known as 3D metal powder laser printing is described in principle in DE 19649865 C1. This process features construction of the molding from pulverulent metallic material via layer-by-layer construction based on the corresponding three-dimensional CAD data of the model of the extrusion die. The three-dimensional CAD data of the model of the extrusion die are generated with the aid of specific CAD software.

[0094] The production process itself features build-up of a metallic material made of successive pulverulent layers. The powder layer is irradiated by an energy source in a prescribed region before the next powder layer is applied. The energy introduced melts the powder, which bonds to give a coherent layer. The selected irradiation energy is such that the material is completely melted over its entire layer thickness. The irradiation is conducted in a plurality of traces over the prescribed region in a manner such that each successive trace to some extent overlaps the preceding trace; the individual traces are thus connected to one another, avoiding production of pores or similar defects. The distance between the traces is selected accordingly. The layering of a plurality of powder layers on top of one another, and irradiation of these, bonds the molten layers resulting from the powder layers applied on top of one another. During the process, an atmosphere of protective gas is maintained, and is effective in the region of the molten metal; this prevents, by way of example, oxidation. The heating of the powder starting material above its melting point, and melting over the entire layer thickness, produces a compact molding with a high level of strength properties.

[0095] After the actual production process there can also, as required by the material used and the precise design, be a need for downstream operations. Thermal processes can be considered in this context, for example in order to increase strength or to dissipate stresses. Processes which modify the surface properties of the molding are also used, for example downstream surface-polishing by means of sandblasting.

[0096] The invention is elucidated in more detail in the examples that follow.

EXAMPLES

Example 1 Production of 3D Printed Extrusion Dies

[0097] Production process: Powderbed Fusion (ASTM, ISO); the following other names are also used as alternatives for the same process (selective laser beam melting (VD)). Plant manufacturers in particular also use the following names: selective laser sintering, selective laser melting SLM™ (Realizer, SLM Solutions), direct metal laser sintering DMLS® (EOS), LaserCUSING® (Concept Laser) among other trademarks.

[0098] Plant description: Concept Laser—M2 curing

[0099] CAD software: Autodesk—Inventor 2017 (for 3D modelling)

[0100] Slicer software: Materialise—Magics 19 (for preparing the 3D model for printing)

[0101] Material Used:

[0102] Raw Material: [0103] stainless steel metal powder

[0104] Supplier Concept Laser [0105] chemical composition corresponding to X2 CrNiMo 17-13-2, 316L, 1.4404. [0106] Particle size distribution: D.sub.10=18.72 μm, D.sub.50=30.10 μm, D.sub.90=45.87 μm [0107] substantially round particle shape

[0108] Properties of Material: [0109] hardness: 190-220 HV [0110] density: 99.5%-99.9% [0111] elongation at break: 41%-52% [0112] minimal tensile strength R.sub.m, min: >614 MPa [0113] minimal yield strength R.sub.p,0.2, min: >486 MPa

[0114] Alternative Material: [0115] preferably metallic material [0116] preferably high abrasion resistance (tool steel) [0117] almost all metals, and also harder plastics, should be acceptable [0118] particle size preferably below 100 μm, preferably between 10 μm and 50 μm

[0119] Process Parameters Used:

[0120] Process Parameters [0121] protective gas: Nitrogen [0122] layer thickness: 25 μm [0123] laser power output: 150-380 W [0124] laser spot diameter: 100 μm [0125] laser spot velocity: 300-1100 mm/s

[0126] Alternative Process Parameters: [0127] protective gas: Preferably noble gas, depending on the reactivity of the metal used [0128] layer thickness: Preferably below 60 μm [0129] Laser power output: Preferably between 50-600 W, depending on the other process parameters [0130] laser spot diameter: preferably below 500 μm [0131] laser spot velocity: Preferably 100-8000 m m/s

[0132] “Autodesk—Inventor 2017” was used here to generate the three-dimensional CAD data of the model of the extrusion die. After modelling of the three-dimensional model, this is converted to an STL format in which the surface of the model is described by triangular faces. The STL format serves for relatively simple further processing of the model in specific data-processing software. The program used here is

[0133] Materialise—Magics. This program uses a build processor to determine the parameters and strategies used in the subsequent production process. The output computer file is then read directly at the 3D printer.

[0134] In the present case the actual production process is followed by low-stress annealing for six hours, and support structures are removed by machining.

Example 2 Production of a Catalyst Composition

[0135] 0.8991 kg (30% by weight, based on the mixture of the diatomaceous earths) of a diatomaceous earth of type MN from EP Minerals, 1.4985 kg (50% by weight, based on the mixture of the diatomaceous earths (of a diatomaceous earth of type Masis from Diatomite SP CJSC and 0.5994 kg (20% by weight, based on the mixture of the diatomaceous earths) of a diatomaceous earth of type Diatomite 1 from Mineral Resources Ltd. are mixed for 30 minutes at 45 revolutions per minute in a Rohnrad mixer (Engelsmann, container volume 32 liters). The mixture of the diatomaceous earths is charged to a Mix-Muller (Simpson, year of construction 2007, container volume 30 liters) and mixed for 2 minutes at 33 revolutions per minute. A first solution consisting of 1.3706 kg of aqueous KOH solution (47.7% by weight) and 0.532 kg of ammonium polyvanadate (Treibacher) is then added over a period of 2 minutes and mixing is continued for 1 minute. 2.1025 kg of 48 percent sulfuric acid are added over a period of 2 minutes, and stirring is continued for one minute at 33 revolutions per minute. 0.3 kg of K.sub.2SO.sub.4 (K+S Kali GmbH) is next added to 1.587 kg of a 50 percent aqueous Cs.sub.2SO.sub.4 solution, and this is added to the Mix-Muller over a period of 2 minutes and mixed at 33 revolutions per minute for one further minute, and then 180 g of a starch solution (7.39% by weight of potato starch in deionized water) are added, with continued mixing. The resultant composition is then further mixed at 33 revolutions per minute until the total mixing time from addition of the diatomaceous earth is 15 minutes.

Examples 3 and 4 Production of Catalyst Moldings

[0136] The geometry of the molding is determined by a die through which the composition to be extruded is conveyed under high pressure. Dies as in FIGS. 18 to 23 (example 3) and 12 to 17 (example 4) were used. The extruded moldings and geometries as in FIG. 24 and, respectively, 25.

[0137] A screw extruder with a single screw is used here. Solids are fed into the screw from above. The extruder is water-cooled. The rotation rate of the conveying screw in the extruder is 10 revolutions per minute. The temperature of the solid during feed and of the moldings on discharge from the extruder is around 50° C. The throughput through an extruder is 6000 kg per day For reasons including non-constant conveying velocity of the strands, result is a length distribution, rather than a uniform length. The average length is moreover dependent on the geometry of the die. The moldings are then dried at 120° C. for 2 h and then calcined at 475° C. for 3 h. Excessively large and excessively small moldings are removed by way of sieve devices.

[0138] The resultant extrudates are shown in FIGS. 26 (example 3) and 27 (example 4).

LIST OF REFERENCE SIGNS

[0139] 10 Die [0140] 12 Entry side of die [0141] 14 Discharge side of die [0142] 16 Grid system [0143] 18 Channel-formers (≙Displacers, ≙Pins) [0144] 20 Metal plate [0145] 22 Interior side wall of die [0146] 24 External wall of jacket [0147] 26 First diameter of channel-formers [0148] 28 Second diameter of channel-formers [0149] 30 Connection of channel-formers [0150] 32 Flow direction of extrudable composition [0151] 34 Metal-printed insert [0152] 36 Connecting web [0153] 38 Diameter constriction of interior side wall [0154] 40 End of channel-formers [0155] 42 Apertures of metal plate [0156] 44 Diameter step of jacket [0157] 48 Shaping of discharge aperture [0158] 50 Discharge aperture [0159] 52 Round shape of channel-formers [0160] 54 Polygonal shape of channel-formers [0161] 56 Shell [0162] 58 Jacket [0163] 60 Extruded catalyst moldings, support or adsorbent moldings [0164] 62 Cavity [0165] 64 Shape of extruded moldings [0166] 66 Walls of extruded moldings [0167] 68 Channels of extruded moldings