METHOD FOR PRODUCING A PRINTER NOZZLE

Abstract

A method for producing a printer nozzle (12, 122, 200) for dispensing a molten material, which has a nozzle body with a receiving section (20) and an outlet section (22, 222) which is, in particular, in the shape of a cone or truncated cone, characterized by the method steps of injection molding powder containing metal and sintering.

Claims

1. A method for producing a printer nozzle (12, 122, 200) for dispensing molten material, in particular a printer nozzle for FFF printing, comprising a nozzle body with a receiving section (20) and an outlet section (22, 222) which is, in particular, in the shape of a cone or truncated cone, characterized by the steps injection molding of powder containing metal, and sintering.

2. The method according to claim 1, characterized in that after the injection, the green body available is debinded and the brown body available is sintered.

3. The method according to claim 1, characterized in that the green body and/or the brown body and/or the sintered body, in particular the green body, are machined.

4. The method according to claim 1, characterized in that the nozzle body is manufactured at least in sections by two-component injection molding.

5. The method according to claim 1, characterized in that an inner channel (26, 226) extending in the longitudinal direction of the nozzle body is formed, which channel has a conical shape on the outlet section side.

6. The method according to claim 1, characterized in that the outlet section is machined by removing layers (232, 236), starting from the distal region of the outlet section (222) to achieve a desired outlet opening diameter.

7. The method according to claim 1, characterized in that the injection molding is carried out using a tool with a tool mandrel, the geometry of which corresponds to at least the inner channel (26, 226) to be produced, in particular the inner channel and outlet opening (24, 130, 230) to be produced.

8. The method according to claim 1, characterized in that the two-component injection molding produces a first region (29) of the nozzle body, which preferably delimits the conical region (27) of the inner channel (26) at least partially, and a second region, wherein for the first region a material is used that is more wear-resistant than that of the second region.

9. The method according to claim 1, characterized in that a powder based on iron materials is used as the powder.

10. The method according to claim 1, characterized in that at least one material from the group of unalloyed steel, low-alloyed case-hardened steel, higher-alloyed ferritic steel and austenitic steel is used as the iron base material.

11. The method according to claim 1, characterized in that a low-alloy steel is one with at least 0.1% by weight to 1.3% by weight of carbon, especially one with the following alloying elements in % by weight 0.1-1.3% C 0-2% Si 0-1% Mn 0-2% Cr 0-0.5% Mo 0-8% Ni residual Fe and unavoidable impurities, is used.

12. The method according to claim 1, characterized in that a higher alloy steel is one with a proportion by weight of carbon between 0.01% and 2.5% and at least 12% of at least one of the elements chromium and nickel, in particular one with the alloying elements 0.01-2.5% C 0-3% Si 0-3% Mn 0-40% Cr 0-3% Mo 0-45% Ni residual Fe and unavoidable impurities, wherein at least 12% by weight of at least one of the elements Cr or Ni is contained, is used.

13. The method according to claim 1, characterized in that a low-alloy steel with an alloy composition of the metal powder in % by weight is used as follows: 0.7-1.1% C 0.0-0.4% Si 0.2-0.5% Mn 1.3-1.7% Cr residual Fe and unavoidable impurities.

14. The method according to claim 1, characterized in that a low-alloy steel with an alloy composition of the metal powder in % by weight is used as follows: 0.1-0.6% C 0.0-0.2% Si 18-23% Ni 22-28% Cr 1.0-1.6% Nb residual Fe and unavoidable impurities.

15. The method according to claim 1, characterized in that the sintered body, if necessary after machining, is subjected to a heat treatment, in particular hardening, such as case hardening, tempering, carbonitriding, nitriding.

16. The method according to claim 1, characterized in that the powder used for the first region (29) of the printer nozzle (12, 122, 200) is one with a material based on the group of cobalt and nickel.

17. The method according to claim 1, characterized in that that hard particles such as oxides, carbides, nitrides and/or PCD are mixed into the base material, in particular that for the first region (29) of the printer nozzle (12, 122, 200).

18. The method according to claim 1, characterized in that hard particles are used in % by weight of the mixture of hard particles and base material: TABLE-US-00002 carbides, such as WC, 1-50% oxides, such as Al.sub.2O.sub.3, Y.sub.2O.sub.3, 0.1-5.0% nitrides, such as BN, 0.1-5.0%

19. The method according to claim 1, characterized in that metal particles of a numerical metal particle size distribution D.sub.90=50 ?m, in particular D.sub.99=40 ?m, are used.

20. The method according to claim 1, characterized in that the powder used is preferably one which contains 50% by weight to 80% by weight of metal powder and 20% by weight to 50% by weight of binder.

21. The method according to claim 1, characterized in that as a binder at least one material from the group polyamide, polyoxymethylene, polycarbonate, styrene-acrylonitrile copolymer, polyimide, natural wax and oil, thermoset, cyanates, polypropylenes, polyacetates, polyethylenes, ethylene-vinyl acetates, polyvinyl-alcohols, polyvinyl chlorides, polystyrene, polymethyl methacrylates, aniline, water, mineral oil, agar, glycerin, polyvinyl butyryl, polybutyl methacrylate, cellulose, oleic acid, phthalate, paraffin, wax, in particular carnauba wax, ammonium, polyacrylate, diglyceride stearates and oleates, glyceryl monostearates, isopropyl titanates, lithium stearates, monoglycerides, formaldehydes, octyl acid phosphates, olefin sulfonates, phosphate esters, acid fatty alcohol esters, stearic acid, zinc stearates is used.

22. The method according to claim 1, characterized in that that a binder is used that contains the following components: a) 10% by weight to 50% by weight of polyamide, b) 40% by weight to 80% by weight of acid fatty alcohol esters, and c) 2% by weight to 20% by weight of an organic acid.

23. A printer nozzle (12, 122, 200) manufactured according to claim 1.

24. Use of a printer nozzle (12, 122, 200) according to claim 23 for filament 3D printing (FFF printing).

25. Use according to claim 24, wherein pure plastic or filled plastic, in particular plastic filled with ceramic, renewable raw material such as wood, and/or plastic-coated metal, is printed using the printer nozzle (12, 122, 200).

Description

[0079] FIG. 1 shows a schematic representation of a printer head in detail and

[0080] FIGS. 2, 3 show embodiments of printer nozzles.

[0081] FIG. 1 shows a section of a printer head 10 intended for FFF printing, by means of

[0082] which molten plastic, which may be filled, is applied in layers to a substrate in order to produce a body using the additive process according to a 3D model. The printer head has a printer nozzle 12 manufactured according to the invention, which is screwed into a heating block 14. The printer nozzle 12 merges into a section 25 that guides plastic threads and is surrounded by a heat sink 16 at a distance from the heating block 14. The distance between heating block 14 and heat sink 16 serves as a heat insulator.

[0083] FIG. 1 shows several layers 17 as an example, which are successively applied onto one another, with a next layer of liquid plastic being applied onto a solidified layer.

[0084] The printer nozzle 12 consists of a nozzle body, which in turn consists of a receiving section 20 with an external thread for screwing into the section 14 and an outlet section 22 having a cone or truncated cone shape with a nozzle opening 24, through which the plastic 25 is dispensed.

[0085] In the longitudinal axis direction and coaxially surrounding the longitudinal axis, a nozzle channel 26 runs within the nozzle 12, i.e. the nozzle body, which channel tapers conically towards its distal end, i.e. towards the nozzle outlet opening 24 (section 27), as is self-explanatory from the drawing.

[0086] The nozzle 12 is manufactured using metal powder injection molding and sintering. Metal powder of a suitable alloy is kneaded with a binder to form a homogeneous powder mixture and heated.

[0087] The following process steps are used to produce the metal mixture, i.e. the feedstock: [0088] charging the metallic and organic components, [0089] heating, mixing, shearing to form a homogeneous mass, [0090] discharge and, if necessary, crushing into injection-moldable granules.

[0091] The metal mixturethe feedstockis processed in the injection molding process. For this purpose, the feedstock is injected into a closed tool at high pressure. The mold is completely filled and the feedstock is plasticized.

[0092] During injection molding, pressures between 100 bar and 2000 bar, preferably between 400 bar and 1000 bar, are used. The temperatures are between 80? C. and 280? C., preferably between 100? ? C. and 150? C.

[0093] The tool into which the feedstock is injected at high pressure should have a temperature between 10? C. and 150? C., especially between 25? C. and 35? C.

[0094] After cooling, a so-called green compact is removed from the tool in order to then debind it, for example thermally, chemically or catalytically, so that the nozzle 12 is then available as a brown compact.

[0095] Debinding can preferably be carried out in a temperature range between 40? C. and 60? ? C.

[0096] To achieve a precision molded part, sintering is then carried out at high temperatures. A hardening or tempering process can then be carried out.

[0097] Depending on the material from which the pressure nozzle 12 is made in the injection molding process, sintering takes place in the temperature range between 1150? C. and 1350? C.

[0098] Since injection molding enables close-contour production, the nozzle 12 can, if necessary, be used immediately after sintering or hardening. However, there is also the possibility of carrying out machining, which can basically take place in every step of the method, for example the green compact, the brown compact or the sintered component can be machined.

[0099] For successive machining of the printer nozzle or the nozzle bore, which depending on the embodiment should preferably have a diameter between 0.2 mm and 0.6 mm, the following should be mentioned: [0100] metal cutting machining, [0101] laser drilling, [0102] wire erosion, [0103] if necessary, surface grinding, especially of the nozzle end, ie the stop surface and the thread end, as well as [0104] if necessary, vibratory grinding.

[0105] Preferably, standard M6 printing nozzles with a diameter of 0.2 mm, 0.4 mm and 0.6 mm are produced using the method according to the invention.

[0106] Iron material is particularly suitable as a base material for the metal powder. A material from the group of unalloyed steel, low-alloyed case-hardened steel, higher-alloyed ferritic steel and austenitic steel can be used.

[0107] There is also the possibility of making regions of the nozzle 12 particularly wear-resistant by means of two-component injection. For this purpose, corresponding regions 29, in particular the inner channel 26 in the region of the nozzle outlet 24, can be made from a material which has, for example, cobalt or nickel as the base material, wherein hard particles such as oxides, carbides, nitrides and/or polycrystalline diamond can be mixed in.

[0108] Regardless of this, the numerical particle size distribution of the metal particles should be D.sub.90=50 ?m, in particular D.sub.99=40 ?m. This means that 90% of the particles are smaller than or equal to 50 ?m or 99% of the particles are equal to or smaller than 40 ?m.

[0109] The feedstock to be injected should in particular contain 50 to 80% by weight of metal powder and 20 to 50% by weight of binder.

[0110] It should also be emphasized that as a binder at least one material from the group polyamide, polyoxymethylene, polycarbonate, styrene-acrylonitrile copolymer, polyimide, natural wax and oil, thermoset, cyanates, polypropylene, polyacetate, polyethylene, ethylene-vinyl acetate, polyvinyl-alcohols, polyvinyl chlorides, polystyrene, polymethyl methacrylates, aniline, water, mineral oil, agar, glycerin, polyvinyl butyryl, polybutyl methacrylate, cellulose, oleic acid, phthalate, paraffin, wax, especially carnauba wax, ammonium, polyacrylate, diglyceride stearates and oleates, glyceryl monostearates, isopropyl titanates, lithium stearates, monoglycerides, formaldehydes, octyl acid phosphates, olefin sulfonates, phosphate esters, acid fatty alcohol esters, stearic acid, zinc stearates can be used.

[0111] The inner channel 26 can be formed in the injection molding tool by means of a mandrel the outer geometry of which corresponds to the inner geometry of the inner channel, taking into account the shrinkage during debinding and in particular during sintering.

[0112] It is possible to produce the nozzle body with an inner channel and nozzle opening using the injection molding process, wherein different mandrels are used for different nozzle openings, as can be seen from FIG. 2.

[0113] The nozzle 122 can have inner channels of different diameters, indicated by lines 124, 126, 128, which channels open into openings 130, 132, 134, which have different diameters. For example, an inner channel with a diameter of 1.75 mm, bounded by line 124, or one with a diameter of 2.85 mm, bounded by line 126, opens into opening 130 with a diameter of 0.25 mm, in the opening 132 with a diameter of 0.4 mm or in the opening 132 with a diameter of 0.6 mm. Furthermore, it is possible to also reproduce internal channels of other internal diameters, which are indicated by line 128.

[0114] An alternative formation of nozzle outlet openings of different diameters is illustrated by FIG. 3. In order to achieve different opening diameters, layers are removed starting from the outlet section 222 of the nozzle 200 from the end face region 227 in order to achieve nozzle openings of different diameters, wherein the inner channel 226 is the same for all openings, while the length of the conical section 228 varies depending on the removed layers.

[0115] In the basic design of the nozzle body 200, it has an opening 230, which is, for example, of 0.25 mm. If a layer 232 is removed, the opening is enlarged in accordance with the angle of inclination of the conical section 228, resulting in a nozzle opening 234 of, for example, 0.40 mm. If a further layer 236 is removed, a larger outlet opening of, for example, 0.60 mm is created.

[0116] The manufacturing process of a printer nozzle according to the invention, with which a viscous feedstock is injected into a closed tool of an injection molding machine, is described below using an example:

[0117] Both value ranges and preferred temperatures are mentioned, which are then listed according to the claims.