Discharge nozzle

Abstract

A discharge nozzle (10) is designed to discharge at least one plasticised, temperature-controlled and solidifiable material (20) into a temperature-controlled construction space (30) for producing a three-dimensional object (40) by means of additive manufacturing, wherein the discharge nozzle (10) has a body (12) with a circumference and a nozzle tip (14) through which the plasticised and temperature-controlled material (20) flows. The discharge nozzle (10) is at least partially surrounded by at least one nozzle insulation (70'), wherein the circumference in the region of the nozzle tip (14) decreases up to an outlet opening (50) of the discharge nozzle (10), and wherein the at least one nozzle insulation (70) follows the circumference at a distance. A device (100) is provided for producing a three-dimensional object (40) by means of additive manufacturing by discharging the material (20) into the construction space (30) using a corresponding discharge nozzle (10).

Description

[0001] Discharge nozzle

[0002] Description

[0003] Reference to related applications

[0004] The present application relates to and claims the priority of German patent application 10 2024 107 704.2, filed on March 18, 2024, the disclosure content of which is hereby expressly incorporated in its entirety into the subject matter of the present application.

[0005] Field of the invention

[0006] The present invention relates to a discharge nozzle configured to discharge at least one plasticized, tempered, and solidifiable material into a construction space for producing a three-dimensional object by means of additive manufacturing, having the features of claim 1, and to a device for producing a three-dimensional object by means of additive manufacturing by discharging at least one plasticized, tempered, and solidifiable material into a construction space, having the features of claim 10.

[0007] State of the art

[0008] In conventional devices for producing a three-dimensional object using additive manufacturing with continuous or discontinuous material discharge, the basis for the process is, for example, plastic granulate, which is fed from a material reservoir to the feed zone of the plasticizing screw via a lateral or vertical material feed nozzle. The molten material is then transported further via a mass reservoir towards the discharge nozzle. All screw zones as well as the discharge nozzle can be separately thermally heated, with the temperature gradient usually becoming increasingly higher towards the discharge nozzle. Higher melt temperatures during deposition promote better fusion of the material already deposited in the build space and thus increase component quality, as, among other things, higher component densities can be achieved. The discharge nozzle is heated, for example, using a heating device, in particular a heating band.The nozzle tip, and in particular the discharge nozzle outlet—the point at which the molten material exits the nozzle—is not directly heated. This nozzle tip is located within the build chamber during material deposition, which is heated by warm air. However, the nozzle tip is cooled by convection within the build chamber. Depending on the material being processed, there can be a significant difference between the set temperatures of the discharge nozzle and the build chamber. This effect is amplified by additional forced convection, particularly due to a forced air flow, caused by a heat source and / or heat sink located directly at the discharge nozzle, to influence the temperature of the component surface directly at the deposition location.This means that the material discharged from the nozzle tip has a lower temperature than specified by the system, since both the nozzle heating device and the temperature sensor on the nozzle are located outside or above the build space. The lower temperature of the molten material to be deposited directly at the usually tapered point of the nozzle tip also means that higher pressures must be applied to transport the material from the material reservoir towards the outlet opening of the discharge nozzle. Depending on the temperature or the difference between the nozzle temperature and the convective air, the heating output of the nozzle heating bands must be readjusted, which can result in temperature fluctuations depending on the control parameters.

[0009] A prior art solution can be found, for example, in EP 3 106 290 A1. In summary, a method and a device for applying a material are disclosed. A 3D printer, a 3D printing head, a machine tool, and a control device for the device are provided. A heating element is used to locally heat an area upstream of the movement of the 3D printing head or extruder. A cooling element, in particular a guide element, cools the applied material and, if applicable, the surface. The heating element and / or the cooling element are advantageously arranged in the direction of movement of the extruder.

[0010] EP 4 017 704 A1 describes a print head for an additive manufacturing system, in particular for a 3D printer, with at least one tempering element, in particular a cooling element, arranged adjacent to the print head and designed in the form of an annular nozzle. EP 3 401 081 B1 discloses a modeling device for producing a three-dimensional object, comprising a plasticizing section that plasticizes a thermoplastic material to convert it into a molten material; an ejection section for ejecting the molten material; a first air-blowing section that blows air from a periphery of the nozzle toward the molten material ejected from the nozzle; a platform on which the molten material ejected from the nozzle is deposited; and a control unit that changes a relative positional relationship between the ejection section and the platform.

[0011] All of these documents focus on heating or cooling the melt to an optimal temperature directly at the deposition point. There is no optimization of the temperature at the nozzle tip or the discharge nozzle outlet with regard to an equally optimal process pressure of the plasticized material in the feed of the injection molding machine or 3D printing machine up to the discharge nozzle outlet, and with regard to an optimal temperature of the plasticized material to be discharged.

[0012] CN 2 08 558 301 U discloses a 3D printing device comprising a printing unit with a print nozzle that tapers conically toward the nozzle opening, and an insulating layer with an opening in which the print nozzle is located. The insulating layer rests on a periphery in the region of the conical taper and protrudes from the periphery in a direction away from the nozzle opening. The insulating layer reduces excessive temperatures in the area of ​​the nozzle opening.

[0013] WO 2022 / 148 935 A1 discloses a device for three-dimensional printing, comprising a print head equipped with a nozzle through which a stream of molten material emerges, and a thermal insulation system for the print head. The device includes a system for conveying at least one gaseous fluid at a controlled temperature in the vicinity of the nozzle outlet. The conveying system comprises a circulation line for the gaseous fluid, in which the print head is placed, wherein the thermal insulation system is configured to enable the fluid to be conveyed in the line. The website www.roboter-bausatz.de sells so-called silicone socks, which can be slipped over the so-called hot ends of generally conically tapered 3D printing nozzles and rest directly against them to prevent temperature fluctuations in the print nozzle.

[0014] In these documents, the temperature of the discharge nozzle is primarily influenced, but only secondarily and to a lesser extent the temperature in the build space, in particular the temperature directly at the build location or storage location of the material.

[0015] Description of the invention

[0016] The invention is therefore based on the object of specifying a discharge nozzle in which a temperature of the discharge nozzle at the nozzle tip can be adjusted to the temperature desired at the deposition location in order to produce good process conditions.

[0017] This object is achieved with a discharge nozzle configured to discharge at least one plasticized, tempered, and solidifiable material into a tempered construction space for producing a three-dimensional object by means of additive manufacturing according to the features of claim 1. The discharge nozzle comprises a body with a circumference and a nozzle tip through which the plasticized and tempered material flows, wherein the discharge nozzle is at least partially surrounded by at least one nozzle insulation, wherein the circumference decreases in the region of the nozzle tip up to an outlet opening of the discharge nozzle, and wherein the at least one nozzle insulation follows the circumference at a distance.The object is also achieved with a device for producing a three-dimensional object by means of additive manufacturing by discharging at least one plasticized, tempered and solidifiable material into a construction space using a corresponding discharge nozzle according to the features of claim 10.

[0018] By optimally adjusting the temperature of the plasticized material to be dispensed at the nozzle tip or the discharge nozzle outlet to the desired temperature at the deposition location, and thereby achieving optimal process pressure of the plasticized material in the feed of the device for producing the 3D object up to the outlet, the process flow and component quality of the object to be produced can be significantly improved. Furthermore, by insulating the nozzle tip with a fluid cushion, in particular an air cushion, between the nozzle insulation and the nozzle tip, the temperature can be kept essentially constant over the entire length of the thermally insulated area.

[0019] Advantageous further developments are the subject of the dependent patent claims. The features listed individually in the patent claims can be combined with one another in a technologically expedient manner and can be supplemented by explanatory facts from the description and details from the figures, thereby demonstrating further embodiments of the invention.

[0020] The body preferably has a heating device, wherein the at least one nozzle insulation is arranged between the heating device and an outlet opening of the discharge nozzle, adjacent to a circumference of the body, extends radially outward from the contact with the circumference and then, at a distance from the circumference of the body, to just before the outlet opening, and completely surrounds the discharge nozzle. The heating device thus sets the optimal temperature in the discharge nozzle for the deposition of the plasticized material up to just before the nozzle tip, which is then passively maintained by the nozzle insulation at the nozzle tip up to the outlet opening of the discharge nozzle.

[0021] Due to the fact that the at least one nozzle insulation preferably extends at a substantially constant distance from the circumference of the body up to just before the outlet opening of the discharge nozzle and thus results in constant spatial conditions between the nozzle insulation and the nozzle tip or constant volumes for the insulating fluid, such as air, the temperature can advantageously be kept extremely constant.

[0022] To maintain temperature consistency, it is also particularly advantageous if the at least one nozzle insulation is preferably made of a material with low thermal conductivity. This results in less heat loss or heat inflow to or from the nozzle tip from the environment.

[0023] It has also proven particularly advantageous if the at least one nozzle insulation preferably comprises at least one of the following materials: metal, ceramic, or plastic. Metals and plastics exhibit particularly high mechanical resistance, whereas ceramic has particularly low thermal conductivity.

[0024] For the maintenance of the discharge nozzle and the adjustment of the discharge nozzle to individual external conditions, it is advantageous that the at least one nozzle insulation is preferably removably attached to a circumference of the body.

[0025] Advantageously, the temperature consistency at the nozzle tip or the outlet opening of the discharge nozzle can preferably be further improved if at least one nozzle insulation and at least one temperature control line, such as a fluid channel or an annular nozzle, are arranged between the heating device and the outlet opening on the circumference of the body, which is designed to supply heat specifically to the three-dimensional object and / or in particular to the build point and thus to locally control the build space temperature in the region of the deposition location where the material is applied. The nozzle insulation and temperature control line extend from the system on the circumference, initially radially outward and then at a distance from the circumference of the body.This allows for advantageous temperature conditions at the construction point to be optimized for the construction of the three-dimensional object, and at the same time, the temperature at the nozzle can be maintained independently by the nozzle insulation.

[0026] An optimum of temperature constancy can advantageously be achieved in that the at least one nozzle insulation and the at least one temperature control line, such as a fluid channel or an annular nozzle, preferably extend at a substantially constant distance from the circumference of the body until shortly before the outlet opening and are at a substantially constant distance from one another at least in the radial direction.

[0027] In order to advantageously achieve a uniform temperature distribution within the body of the discharge nozzle, the heating device preferably comprises at least one heating band arranged on the circumference of the body.

[0028] The features listed individually in the patent claims can be combined with one another in a technologically meaningful manner and can be supplemented by explanatory facts from the description and by details from the figures, whereby further embodiments of the invention are shown.

[0029] The invention will now be explained in more detail using an exemplary embodiment. Fig. 1a shows a schematic view of an apparatus for producing a 3D object,

[0030] Fig. 1 b is a section of Fig. 1a showing the discharge nozzle with the nozzle insulation partially surrounding its body circumference,

[0031] Fig. 2 is a schematic view of a second embodiment of the discharge nozzle according to the invention.

[0032] Description of preferred embodiments

[0033] The invention will now be explained in more detail by way of example with reference to the accompanying drawings. However, the embodiments are only examples and are not intended to limit the inventive concept to a specific arrangement. Before describing the invention in detail, it should be pointed out that it is not limited to the specific components of the device and the specific method steps, since these components and methods can vary. The terms used herein are intended to describe particular embodiments only and are not used in a limiting sense. Furthermore, when the singular or indefinite article is used in the description or claims, this also refers to the plural of these elements, unless the overall context clearly indicates otherwise.

[0034] Fig. 1a schematically shows a device 100 for producing a three-dimensional object 40 such as an additive manufacturing unit. Via a feed unit, designed as a hopper in the exemplary embodiment, solid material is fed to a plasticizing unit 16, in which it is plasticized and fed, for example, by a conveyor screw, to a discharge unit with a discharge nozzle 10. From there, it is discharged via a discharge opening 50 into a temperature-controlled or temperature-adjustable build space 30 in order to produce an object 40 that is manufactured on a slide 18. The material can be discharged dropwise and / or strandwise. The discharge nozzle 10 is designed to discharge at least one plasticized, temperature-controlled and solidifiable material 20 into a temperature-controlled or temperature-adjustable build space 30 for producing the three-dimensional object 40 by means of additive manufacturing.The discharge nozzle 10 has a body 12 through which the plasticized and tempered material 20 flows. The discharge nozzle 10 is at least partially surrounded by at least one nozzle insulation 70. Although only one nozzle insulation 70 is shown in the figures, this can, however, be enveloped and / or surrounded, for example, by a second, additional nozzle insulation. By adjusting the temperature at the nozzle tip 14 or the outlet opening 50 of the discharge nozzle 10, which can be measured by means of a temperature sensor T, for example, to the temperature prevailing at the deposit location 55 and the thereby achievable optimal process pressure of the plasticized material 20 in the feed of the device 100 for producing the 3D object up to the outlet opening 50, the component quality of the object 40 to be produced can be significantly improved. The temperature of the nozzle tip 14 orThe outlet opening 50 of the discharge nozzle 10 thus remains largely unaffected by a convection flow 80 of a fluid located in the construction space 30, such as air. To maintain a constant temperature, it may also be advantageous if only the part of the body 12 that is surrounded by the nozzle insulation 70 protrudes into the construction space 30.

[0035] In Fig. 1 b, further advantageous features of the discharge nozzle 10 are shown enlarged, which are described below.

[0036] In order to keep the temperature substantially constant over the entire length of the thermally insulated region, complete insulation of the nozzle tip 14 by means of a fluid cushion, in particular an air cushion, between the nozzle insulation 70 and the nozzle tip 14 is advantageous. This can be achieved by the body 12 having a circumference that decreases in the region of a nozzle tip 14 up to an outlet opening 50 of the discharge nozzle 10, and by the at least one nozzle insulation 70 following the circumference at a distance.

[0037] It is advantageous if an optimal temperature for the deposition of the plasticized material 20 can be set in the discharge nozzle 10 up to just before the nozzle tip 14. It is also advantageous if this temperature is subsequently passively maintained by the nozzle insulation 70 at the nozzle tip 14 up to the outlet opening 50 of the discharge nozzle 10. This can be achieved by the body 12 having a heating device 60 and by the at least one nozzle insulation 70 being arranged between the heating device 60 and an outlet opening 50 of the discharge nozzle 10, adjacent to a circumference of the body 12.

[0038] The at least one nozzle insulation 70 preferably extends radially outward from the contact area on the circumference and then, at a distance from the circumference of the body 12, to just before the outlet opening 50 and preferably completely surrounds the discharge nozzle 10. To maintain a constant temperature of the nozzle tip 14 or the outlet opening 50 of the discharge nozzle 10, it may also be advantageous if the heating device 60 does not protrude into the temperature-controlled or temperature-adjustable installation space 30.

[0039] In order to keep the temperature constant, it is advantageous to create constant spatial conditions between the nozzle insulation 70 and the nozzle tip 14 or constant volumes for the insulating fluid, such as air, in particular along the body 12. This can be achieved in that the at least one nozzle insulation 70 extends at a substantially constant distance from the circumference of the body 12 until shortly before the outlet opening 50 of the discharge nozzle 10.

[0040] Preferably, the at least one nozzle insulation 70 is made of a material with low thermal conductivity. Particularly high mechanical resistance or low thermal conductivity can be achieved by the at least one nozzle insulation 70 comprising at least one of the materials metal, ceramic, or plastic.

[0041] For the maintenance of the discharge nozzle 10 and the adjustment of the discharge nozzle 10 to individual external conditions, it is advantageous if the at least one nozzle insulation 70 is removably attached to a circumference of the body 12.

[0042] As shown in a second embodiment in Fig. 2, the temperature constancy at the nozzle tip 14 or the outlet opening 50 of the dispensing nozzle 10, as well as at a construction point at which the material is dispensed onto the three-dimensional object, can be advantageously improved by arranging at least one nozzle insulation 70 and at least one temperature control supply line 75, such as a fluid channel or an annular nozzle, between the heating device 60 and the outlet opening 50 on the circumference of the body 12. The temperature control supply line 75 can be connected to a temperature control source (not shown in the drawing), so that, as indicated by the arrows 90, temperature-controlled air or another gaseous medium or fluid can be supplied to the construction point in a targeted manner.At the same time, however, the at least one nozzle insulation 70 is arranged on the nozzle body 12 in such a way that this temperature control occurs independently of the desired temperature for the material in the nozzle body. This temperature control is therefore not influenced by the temperature control of the build point due to the nozzle insulation 70. The temperature control line is thus configured to supply heat to the three-dimensional object 40 and / or to locally control the build space temperature in the area of ​​the deposit location 55.

[0043] Preferably, the at least one nozzle insulation 70 and the temperature control supply line 75, such as a fluid channel or an annular nozzle, extend from the peripheral contact point, initially radially outward, and then spaced apart from the periphery of the body. They are preferably spaced apart from one another at least radially and completely surround the discharge nozzle 10. Thus, in the radially outer layer, for example, tempered air can reach the construction point, while the inner layer contributes to the temperature control of the body 12.

[0044] An optimum of temperature constancy can advantageously be achieved in that the at least one nozzle insulation 70 and the temperature control supply line 75 extend at a substantially constant distance from the circumference of the body 12 up to just before the outlet opening 50 and are at a substantially constant distance from one another at least in the radial direction.

[0045] Because the heating device 60 has at least one heating band arranged on the circumference of the body 12, a uniform temperature distribution within the body of the discharge nozzle can advantageously be achieved.

[0046] The device schematically illustrated in Fig. 1a is a device 100 for producing a three-dimensional object by means of additive manufacturing by discharging at least one plasticized, tempered, and solidifiable material 20 into a build space 30, characterized by the use of a discharge nozzle 10 as described above. Tests have shown that with such nozzle insulation, the process pressure could be significantly reduced because, due to the now higher melt temperature of the material directly at the nozzle outlet, the melt viscosity is lowered and thus the resistance that must be applied for the melt to flow out of the outlet opening 50 is reduced. This leads to a lower shear stress on the material at the nozzle outlet, which can additionally increase the component quality.In addition, process stability is significantly increased, as fewer pressure fluctuations can be detected during the process. The heating output of the heating band at the nozzle is also less dependent on the build chamber temperature.

[0047] Especially when additional forced convection is present directly at the discharge nozzle, due to a heat source and / or heat sink located there, nozzle insulation has a positive effect on process stability. It goes without saying that this description is subject to various modifications, changes, and adaptations within the range of equivalents to the appended claims.

[0048] List of reference symbols

[0049] 10 Discharge nozzle

[0050] 12 bodies

[0051] 14 Nozzle tip

[0052] 16 Plasticizing unit

[0053] 18 slides

[0054] 20 materials

[0055] 30 installation space

[0056] 40 three-dimensional object

[0057] 50 Exit opening

[0058] 55 Storage location

[0059] 60 Heating device

[0060] 70 nozzle insulation

[0061] 75 Tempering supply line

[0062] 80 Fluid convection

[0063] 90 arrows

[0064] 100 Device for the production of 40

[0065] T Temperature sensor

Claims

Patent claims 1. Discharge nozzle (10) configured to discharge at least one plasticized, tempered, and solidifiable material (20) into a tempered or temperable construction space (30) for producing a three-dimensional object (40) by means of additive manufacturing, wherein the discharge nozzle (10) has a body (12) with a circumference and a nozzle tip (14) through which the plasticized and tempered material (20) flows, characterized in that the discharge nozzle (10) is at least partially surrounded by at least one nozzle insulation (70), that the circumference decreases in the region of the nozzle tip (14) up to an outlet opening (50) of the discharge nozzle (10), and that the at least one nozzle insulation (70) follows the circumference at a distance.

2. Discharge nozzle (10) according to claim 1, characterized in that the body (12) has a heating device (60) and that the at least one nozzle insulation (70) is arranged between the heating device (60) and an outlet opening (50) of the discharge nozzle (10) on a circumference of the body (12), extends from the contact with the circumference initially radially outwards and then at a distance from the circumference of the body (12) until shortly before the outlet opening (50) and preferably completely surrounds the discharge nozzle (10).

3. Discharge nozzle (10) according to claim 1 or 2, characterized in that the at least one nozzle insulation (70) extends at a substantially constant distance from the circumference of the body (12) until shortly before an outlet opening (50) of the discharge nozzle (10).

4. Discharge nozzle (10) according to one of the preceding claims, characterized in that the at least one nozzle insulation (70) consists of a material with a low thermal conductivity.

5. Discharge nozzle (10) according to one of the preceding claims, characterized in that the at least one nozzle insulation (70) comprises at least one of the materials metal, ceramic or plastic.

6. Discharge nozzle (10) according to one of the preceding claims, characterized in that the at least one nozzle insulation (70) is removably attached to a circumference of the body (12).

7. Discharge nozzle (10) according to one of the preceding claims, characterized in that between a heating device (60) and an outlet opening (50) of the discharge nozzle (10) on the circumference of the body (12) at least one nozzle insulation (70) and at least one temperature control line (75) surrounding it, which is designed to supply heat to the three-dimensional object (40) and / or to locally control the temperature of the construction space in the region of the deposit location (55), are arranged, which extend from the contact on the circumference initially radially outwards and then at a distance from the circumference of the body (12).

8. Discharge nozzle (10) according to claim 7, characterized in that the at least one nozzle insulation (70) and the at least one temperature control supply line (75) extend at a substantially constant distance from the circumference of the body (12) until shortly before the outlet opening (50) and are at a substantially constant distance from one another at least in the radial direction.

9. Discharge nozzle (10) according to one of claims 2 to 8, characterized in that the heating device (60) comprises at least one heating band which is arranged on the circumference of the body (12).

10. Device (100) for producing a three-dimensional object (40) by means of additive manufacturing by discharging at least one plasticized, tempered and solidifiable material (20) into a tempered or temperable construction space (30), characterized by the use of a discharge nozzle (10) according to one of the preceding claims 1 to 9.

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