EP4240701A1

EP4240701A1 - Glass extrusion assembly and glass extrusion method for the direct manufacturing of compact, three-dimensional and geometrically defined semifinished products and components made of glass

Info

Publication number: EP4240701A1
Application number: EP21811243.1A
Authority: EP
Inventors: Jens Bliedtner; Anne-Marie SCHWAGER; Jens Kobelke; Jan Dellith; Andreas Hopf; Volker Reichel
Original assignee: Ernst-Abbe-Hochschule Jena; Leibniz Institut fuer Photonische Technologien eV
Current assignee: Ernst-Abbe-Hochschule Jena; Leibniz Institut fuer Photonische Technologien eV
Priority date: 2020-11-06
Filing date: 2021-10-29
Publication date: 2023-09-13
Also published as: WO2022096061A1; DE102020129314A1

Abstract

The invention relates to a glass extrusion assembly comprising a peripheral mirror system (3), a switchable heatable nozzle (4) having an outlet opening (41), and a transport system (2). The nozzle (4) is situated in a process chamber surrounding a heatable platform (42). The nozzle (4) and the platform (42) can be positioned in three axes relative to one another by a movement unit. The peripheral mirror system (3) is situated outside the process chamber (5). For extrusion, the glass fibre (7, 8) to be extruded can be continuously introduced from a material feed unit (1) into the nozzle (4) by means of the transport system (2), through the peripheral mirror system (3), via an inlet opening (51) of the process chamber (5). For the purpose of heating, the nozzle (4) can be irradiated using at least one controlled laser (63), wherein, in the operating state, a thermocouple monitors the heating temperature during the heating of the nozzle (4), such that the glass fibre heated by the laser light is above its melting point in the form of a flowable fluid in the nozzle (4) and can flow out of the outlet opening (41) towards the platform (42). The sub-systems can be controlled/operated simultaneously and precisely by an open-loop and closed-loop control unit and by this glass extrusion assembly being operated as intended.

Description

Glass extrusion arrangement and glass extrusion process for the direct production of compact, three-dimensional and geometrically defined semi-finished products and components made of glass

The invention relates to a glass extrusion arrangement and a generative glass extrusion process for the direct production of compact, three-dimensional and geometrically defined semi-finished products and components made of glass using at least one continuously supplied, commercially available and optionally coated glass fiber, the fiber material being both low-melting glass systems (Tg << 1000 °C, such as fibers for image transmission) as well as higher-melting glass systems (Tg >> 1000°C, such as pure or modified silica glass) can be used.

Generative (additive) manufacturing processes represent a way of creating three-dimensional objects / components that differ significantly from classic removing / machining manufacturing processes, such as turning, drilling, milling, sawing or planing, in that a component is created by joining and Material quantities are joined together, which among other things leads to significantly greater freedom of form.

One form of assembling and assembling is the selective positioning of discrete amounts of material against and on top of each other to create a component in layers. For this purpose, quantities of material are dispensed from an extruder in a fluid state onto a carrier, on which they then cool and solidify, which is why these 2D or 3D printing processes are referred to as extrusion processes.

A suitable device for a plastics extrusion process for producing three-dimensional objects is disclosed in DE 690 33 809 T2. This device comprises a heatable extruder with a heatable nozzle that can be moved in the x, y, and z direction relative to a carrier plate on which the component is built. The starting material is fed to the extruder in the form of a plastic rod or a flexible plastic strand, heated to its melting point in the extruder and discharged as a free-flowing fluid through a nozzle.

For the purpose of heating the extruder, a controlled resistance heater is provided which is connected to a thermocouple to heat the feedstock just above the melting point.

In order to ensure that the starting material is ejected as a fluid through the nozzle of the dispensing head, there is a supplementary electrical heating device which heats the nozzle in a temperature-controlled manner.

The volume rate of the delivered fluid is controlled by the feed of the flexible strand. The smaller the diameter of the flexible strand, the more precisely the volumetric flow rate of fluid delivery can be controlled.

Effective on/off fluid delivery can be achieved simply by stopping the feed motors.

Accurate temperature control to which the flexible strand is heated in the dispensing head also helps regulate its flow.

The disadvantage of this arrangement and this method is that it is limited to the use of thermoplastics and thus low temperatures below 200°C.

In general, 3D printing with glass is still relatively uncommon and largely unexplored.

The Karlsruhe Institute of Technology (KIT) is currently developing a special stereolithography process (SLA process) to print glass bodies.

For this purpose, a composite material made of photopolymer and glass powder is developed, which is solidified by UV radiation. This creates a green body.

In order to generate a pure glass component, the green body must be debound and sintered in a second process. This process removes the photopolymer, which acted as a binder, and the glass particles form a solid bond (also known as sintering).

The Missouri University of Science and Technology follows a different technical approach, which is based on the established processes of "welding with filler wire" and "laser cladding with wire".

Glass rods are used as filaments, which are melted using a CO ₂ laser.

A three-dimensional body is created on the construction platform by moving a construction platform in the x-y-z direction and simultaneously laying down / applying the melted glass rod (technical approach of the Laser Center Hanover).

Lawrence Livermore National Laboratory uses Direct Ink Writing for 3D glass printing.

For this purpose, a suspension of pyrogenic silica and tetraethylene glycol dimethyl ether is extruded in layers through a nozzle onto the construction platform.

Almost transparent and dense glass components can be generated by a subsequent compression and sintering process.

The Massachusetts Institute of Technology (MIT) has developed a material extrusion printer for optically transparent glasses.

The extrudate is present as a glass melt in a melting furnace.

This melting furnace is arranged above the processing area and the melt is extruded in layers from the melting furnace through a heated nozzle as a glass strand onto the construction platform under pressure.

The process chamber has a processing temperature of approx. 550°C.

When the build process is complete, the process chamber is slowly cooled to avoid stress-induced glass breakage.

Due to the structure at MIT, only minimal layer thicknesses of 4 mm can be generated with this technical solution, so that only works of art can be produced due to this very low level of detail of the objects.

The Micron 3D company has a device structure that is analogous to that at MIT.

With this technical solution, layer thicknesses of 100 μm can be achieved through special adjustments to the nozzle design, with typical extrusion materials being borosilicate glass or soda-lime glass.

A disadvantage of this extrusion process for glass is that a melting furnace is required to melt the extrudate.

This melting step is very energy- and time-consuming and therefore very cost-intensive.

On the one hand, the furnace must be thermally stable, which is particularly critical for high-melting glass types.

On the other hand, the melting furnace must be thermally decoupled from the actual processing area in order to avoid temperature gradients (which lead to undesirable tension and thus reduced mechanical stability of the extruded component) and the associated process fluctuations.

In order to be able to generate three-dimensional components, the entire solid melting furnace is moved in x-y directions, which is also a disadvantage. (A z-axis is built into the process chamber.)

Another disadvantage is that due to the processing temperatures of approx. 550° C. in the process chamber and over 1000° C. in the melting furnace, the movement units have to be designed for extreme conditions, which involves a certain amount of effort and corresponding costs.

In addition, the extrusion volume is dependent on the capacity of the melting furnace, which is also disadvantageous.

If new glass material is required for the process, the furnace cover must be removed and the glass melt placed in the melting furnace. This discontinuous feeding takes place under the highest security measures and with equipment from the glass foundry, which represents a further disadvantage. This process step also means that molten glass must be ready for the process in a separate furnace, which in turn increases the complexity and costs of the entire extrusion process.

However, additive manufacturing processes for the production of compact, three-dimensional and geometrically defined semi-finished products and components made of glass are a promising addition to already established production processes and are of great importance for individualized production due to their high flexibility and the "tool-free" production, so that it is of great interest to further improve these procedures.

However, the direct additive production of components made of glass has hardly been established to date. Initial approaches are based on powder bed methods such as selective laser melting (SLM) or selective laser sintering (SLS).

Stereolithographic methods (SLA) with powder-filled binder systems have already been successfully tested, but are still in the experimental stage.

Well-known extrusion methods currently focus on the processing of low-melting glass systems using extrusion masks, e.g. for the production of complex preforms.

A method is known from WO 2019/079 704 A1, for example, in which bulk metal glasses are treated with the aid of a laser.

However, coated glass fibers or glass strands cannot be used for glass extrusion in 3D printing techniques using the technical solution according to the teaching of WO 2019/079704 A1.

WO 2015/065 936 A1 discloses a method in which quartz glass can be produced additively by melting quartz glass fibers using a CO ₂ laser source. In this process, combined laser heads focus laser radiation onto the glass fiber to melt it, using a three-axis system to move the printing surface and glass substrate. However, direct extrusion of coated glass fibers or glass strands cannot be made possible by the technical solution according to the teaching of WO 2015/065 936 A1.

WO 2015/120 430 A1 teaches a method for the production of vitrified three-dimensional quartz glass molded parts, based among other things on the method of selective laser beam sintering with material-specific scan and parameter concepts.

The use of synthetic and natural silica glass powders enables additive manufacturing using selective high-temperature laser sintering (HT-SLS).

However, direct extrusion of coated glass fibers or glass strands cannot be made possible by the technical solution according to the teaching of WO 2015/120 430 A1.

WO 2015/077 262 A1 discloses the 3D printing of glass using the SLE (Selective Laser Etching) method. This procedure is a two-step, subtractive 3D process.

In a first step, ultra-short pulsed laser radiation is focused. This happens on a micrometer-sized volume inside transparent materials. The laser radiation is only absorbed in the focus by multi-photon processes. The material heats up briefly and strongly, then cools down quickly and changes locally and permanently. There are no microcracks.

For the second process step, the exposed workpiece is removed from the laser exposure system and developed in a wet-chemical etching bath. The laser-modified glass is dissolved very selectively, with this etching process starting on the outside and then working its way inwards along the modification in order to create the inner structures.

However, direct extrusion of coated glass fibers or glass strands cannot be made possible by the technical solution according to the teaching of WO 2015/077 262 A1. WO 2016/198 148 A1 discloses the production of 3D-printed components with ultrasonically controlled microscale structure, with in situ manipulation of the discontinuous fiber structure during the printing process within a 3D-printed polymer composite architecture, which is a novel method for the immediate alignment of Microscale glass fibers in a selectively cured photocurable resin system.

Ultrasonic forces are used to align the fibers in the desired 3D architecture. To achieve this, a switchable, focused laser module is mounted on a support of a three-axis 3D printing table over an ultrasonic alignment device containing a mixture of photocurable resin and discontinuous glass fiber reinforcement 14 μm in diameter (50 μm in length).

However, direct extrusion of coated glass fibers or glass strands cannot be made possible by the technical solution according to the teaching of WO 2016/198148 A1.

On the subject of 3D printing of glass, US 2017/0283297 A1 discloses a method for 3D printing of objects/components in which materials are deposited from walls by multiple print heads, while the print heads are moved along the 3D coordinates of the walls, where the operations of filling the material into the printheads, melting the material in the printheads and metering the melted material through an opening in each of the printheads are carried out simultaneously while the printheads are moved along the 3D coordinates so that the object / component is built.

US 2017/0283297 A1 also discloses an apparatus for 3D printing of objects/components, which includes a print head and the mechanism for 3D positioning of the print head, using a glass melting furnace as the print head and an alignment device for aligning a plane of the wall, which is arranged in such a way as to allow the formation of the plane of the wall (2D or 3D), after the material has been deposited (=extruded) through an opening in the print head.

According to US 2017/0283297 A1, this method for printing walls and structures made of glass is said to be of particular interest for the construction industry, because glass, in contrast to concrete, is easier to process and more detailed. Multi-layer glass walls are to be optionally equipped with thermal conductivity, colors and light reflections.

Since glass is resistant to germs and almost maintenance-free, the walls and structures made of 3D printed glass can be used in refrigeration facilities and hospitals.

However, direct extrusion of coated glass fibers or glass strands for 3D printing of glass cannot be made possible by the technical solution according to the teaching of US 2017/0283297 A1.

DE 10 2018 109 131 A1 discloses a device for producing a three-dimensional object made of glass or glass ceramic, in particular by means of additive manufacturing technology, comprising at least the following components:

• at least one print head with at least one print nozzle,

• a device for feeding printing material from a reservoir to the print head,

• at least one laser source to form a heating zone,

• a print table for separating the print material, with the heating zone being placed between the print head and the print table and the print head and print table moving relative to each other in the x, y and z directions and the device having at least one of the following components:

- A device for measuring the temperature in the heating zone and a device for regulating and / or controlling the temperature in the

- heating zone, whereby the temperature in the heating zone is adjusted in such a way that the printing material has a viscosity in the range from 104 dPas to 107.6 dPas a device for cleaning the surface of the printing material before it enters the print head and/or - a device for treating the surface of the print material before it enters the printhead.

According to the technical teaching of DE 10 2018 109 131 A1, the extrusion cannot be switched on and off quickly and no direct extrusion of coated, commercially available glass fibers or glass strands (so-called endless fibers) for 3D printing of glass is possible.

The object of the present invention is to specify a glass extrusion arrangement and a glass extrusion method for the direct production of compact, three-dimensional and geometrically defined semi-finished products and components made of glass, which avoids the disadvantages of the prior art mentioned above and in particular an extrusion of coated glass fibers or glass fiber strands with the The aim of the additive production of high-quality 3-dimensional glass components is made possible, whereby the extrusion should be able to be switched on and off quickly and, as glass fiber material, both low-melting glass systems (Tg<< 1000°C) and higher-melting glass systems (Tg>> 1000°C, such as pure or modified silica glass) can be used.

According to the invention, this object is achieved by the features of the 1st and 3rd claim.

Further advantageous configuration options of the invention are specified in the subordinate patent claims.

The essence of the invention is that a single-stage, continuous process using a glass extrusion system enables the direct production of compact, 3-dimensional and geometrically defined semi-finished products and components made of glass using a continuously supplied, commercially available and optionally coated glass fiber.

Low-melting glass systems (Tg << 1000°C, e.g. fibers for image transmission, such as oxidic crown or flint glasses) as well as higher-melting systems (Tg >> 1000°C, For example, from differently modified silica glass, such as photonic crystal fibers) are processed.

Technologically, the process is based on a glass extrusion arrangement that is made up of several individually controllable subsystems. Only the combination of these subsystems and their simultaneous operation with precisely controlled parameters makes the method mentioned possible.

The glass extrusion arrangement comprises the following subsystems: - a peripheral mirror system, which is designed according to the technical teaching of DE 10 2009 021 448 B3, - a switchable, heatable nozzle, which is designed according to the technical teaching of DE 10 2016 125 166 A1 and which one Carrier plate / platform is spatially assigned, these two elements to each other in 3 axes (X, Y and Z axis) can be positioned, and - a transport system.

The switchable, heatable nozzle can be moved in the x, y and z direction relative to the carrier plate/platform on which the glass component is built.

As an alternative to this, however, the support plate/platform can also be movable in relation to the nozzle in the directions x, y and z, or there is also the further alternative possibility that both the nozzle and the support plate/platform can be moved in order to y and z direction to be adjustable.

The starting material is continuously fed to the switchable, heatable nozzle by means of the transport system through the peripheral mirror system in the form of a commercially available and optionally coated glass fiber, with the peripheral mirror system (CO ₂ - or other lasers radiating for heating, alternatively also flame-based and mechanical Heating possible) preheating of the glass fiber and complete removal of any existing sheathing from the glass fiber takes place and in the nozzle (with the function of an extrusion unit) the final heating of the glass fiber to its softening range takes place, so that a free-flowing fluid made of glass is discharged via the outlet opening of the movable, heatable nozzle.

For the purpose of heating the nozzle, at least one controlled laser is provided for heating, with a thermocouple monitoring the heating temperature during heating so that the glass fiber heated by the laser radiation is present in the nozzle as a free-flowing fluid above its softening point.

The volume rate of the delivered fluid glass is controlled by the feed of the glass fiber through the transport system with adjustable feed motors. The smaller the diameter of the glass fiber used, the more precisely the volumetric flow rate of the fluid glass delivery can be controlled.

Precise control of the temperature to which the glass fiber is heated in the switchable nozzle in the softening region also aids in controlling the flow of the fluid glass being dispensed.

The peripheral mirror system according to DE 10 2009 021 448 B3 comprises at least one controlled laser (e.g. CO ₂ laser) and a peripheral mirror with a peripheral mirror system axis and an optical system which couples a beam of laser light perpendicular to the peripheral mirror system axis into the peripheral mirror in such a way that that, after multiple reflections, it impinges on the glass fiber to be treated, whose axis runs in the same direction inside the peripheral mirror as the axis of the peripheral mirror system.

This subsystem of the glass extrusion arrangement (in the form of the peripheral mirror system) is operated by coupling the laser beam bundle into the peripheral mirror for a predetermined processing time, with the glass fiber, the peripheral mirror and/or the optical system being held relatively still or moved relative to one another. The switchable, heatable nozzle as a subsystem of the glass extrusion arrangement is already known per se from a device according to the technical teaching of DE 10 2016 125 166 A1 for the generative production of a three-dimensional object from a material that can be solidified by cooling and has a temperature-dependent viscosity, containing a heatable Platform as a carrier on which the three-dimensional object / component is produced in layers, and a nozzle with a nozzle opening for extrusion of the molten glass fiber (fluid), whereby the heated platform and the switchable, heated nozzle are three-dimensional in relation to each other in x, y and z direction with a feed rate are movable.

In the glass extrusion arrangement, the temperature of the fluid and its viscosity can be specified by the laser-heated nozzle, with the energetic radiation, e.g. CO ₂ laser radiation or other laser radiation, causing a controllable energy input with a specified radiation intensity over a specified emission time into the nozzle and with simultaneously controlled ejection of the fluid, in that a partial volume of the fluid in the nozzle is heated to a passage temperature that is higher than the specified temperature, at which the viscosity of the partial volume is so low that the partial volume, when subjected to a specified pressure, passes through the nozzle opening .

For this purpose, the nozzle in the glass extrusion arrangement according to the present invention is supplied with a commercially available glass fiber which has already been preheated by the peripheral mirror system and has been freed from its possibly existing coating.

The actual melting process takes place in the switchable, heatable nozzle (fiber extrusion unit). For this purpose, several laser sources are advantageously arranged around them. The energetic irradiation of the nozzle heats it up and at the same time melts the glass of the preheated glass fiber to be extruded.

It is important and essential that the preheating of the glass fiber and the removal of any existing coating of the glass fiber by the Circumferential mirror system in the glass extrusion arrangement before entry into the switched nozzle, as already described above, takes place in that energetic radiation, e.g. whereby it is possible to irradiate the glass fiber circumferentially with the beam and thereby to heat it up.

The rapid switching of the laser and the associated dosing of the energy input into the switchable, heatable nozzle allows the viscosity of the material in the softening area to be set in a defined manner by the last temperature increase for the extrusion.

The beam guidance from the energy source(s) to the coupling point at the peripheral mirror and at the switchable nozzle can be realized in different ways.

With the help of optical components (collimation and focusing optics), the energy beam can be guided to the desired position. Depending on the beam parameters in combination with optical components, the focus diameter and the associated intensity can be defined.

The focus diameter and thus the intensity can be varied and adjusted by regulating the laser power and varying the distance between the starting material and the energy source/optical components or between the energy source and the optical components. This makes it possible to define which volume is to be melted and which should be available for the construction process (3D printing).

With these technical measures alone, a very flexible production can be generated, which has not been the case with rapid technologies up to now. With additive processes, it is necessary to divide the component to be created into process-dependent single-layer filament sections. Thanks to the new technical solution made available in the form of the glass extrusion arrangement and the glass extrusion process, it is now possible to vary each individual layer depending on the component and geometry.

Flat surfaces can be applied with a high volume because the step aspect does not come into play here.

As soon as the geometry takes on three-dimensional contours, the slice layer height is decisive for the dimensions of the stair step geometry and thus significantly determines the dimensional accuracy and surface quality.

By varying the volume, with the help of this new technical solution, each layer edge structure can be adjusted and manufactured depending on the required specifications.

It is also possible to react to different starting materials by varying the laser wavelength and focusing the exposure spot of the laser radiation. - Each material has an absorption coefficient depending on the wavelength used and independent of the focus. This coefficient indicates how much energy can be absorbed by the material in relation to the output power. This absorbed energy is converted into heat and heats the material up to the required processing temperature. This makes it possible to switch between low-temperature and high-temperature glasses with little effort.

The switchable, heatable nozzle can be part of an extrusion unit, which can be designed as a single or multiple chamber system. At least one switchable, heatable nozzle is then arranged on each of these chambers.

A glass fiber with a different starting material or a glass fiber with the same starting material but with different doping properties can be melted through each nozzle of each of the individual process chambers. On the one hand, this makes it possible to produce gradient workpieces that do not only consist of two components. From this, new design options and bases for three-dimensional components can be generated and derived. Because each chamber can be filled individually, composite structures can also be manufactured.

On the other hand, there is also the possibility of precisely defining continuous material component progressions and consequently property progressions.

Depending on how the laser sources for the individual chambers are switched on and off, stepped or graduated transitions can be generated.

Due to the compact design of the individual process chambers, each with a switchable, heatable nozzle including the respective laser source, a large number of chamber systems can be combined into a complete system. As a result, there are no limitations with regard to different material combinations.

Furthermore, volume and cross-section can also be defined via the movement kinematics of the switchable, heatable nozzle or the heatable carrier plate.

With this procedure, the processing speed (as known from the prior art) depends on the heating power and the material feed. In the glass extrusion arrangement and the glass extrusion process, new glass of the glass fiber must be thermally converted to the state of plastic deformability and flowability by the peripheral mirror system and the subsequent switchable nozzle and can only then be applied to the heatable carrier plate. The time required for this determines the maximum processing speed.

In addition to the heating output, cooling also plays a role, which is understood to be a spontaneous process. However, it is also within the scope of the invention to stimulate the cooling process (e.g. by blowing out or air cooling) in order to improve the processing time and the structural accuracy. In contrast to the glass extrusion arrangement and the glass extrusion method, the currently known arrangements and methods do not allow rapid adjustment of the heating output, since the periphery and the components used are not designed for this.

Due to the possibility of quickly switching the switchable, heatable nozzle on and off by means of the laser beam sources (this means that a change between the heating and cooling phase is possible very quickly) and the timely regulation of the energy supplied to it, higher processing speeds can be achieved for the glass extrusion process according to the invention be achieved, which is a very big advantage over the previously known methods.

Process temperatures that are required in a timely manner can also be set. The entire construction process can be made more efficient and effective compared to conventional methods.

Commercially available glass fibers, which are used in fiber optics or telecommunications, for example, serve as the starting material for the glass extrusion process for 3D glass printing.

These fibers exist in the most varied variations (size, length, material) on the market. The glass fibers can be ordered wound up to a length of several kilometers. This almost endless supply of starting material means that the glass 3D printing process can be completed without interruptions. Time-consuming refilling, as with a melting furnace, is no longer necessary.

Standard glass fibers typically have a diameter of 125 μm. Due to these small dimensions, very high levels of detail can be achieved during extrusion. In this way, optical elements such as lenses could be constructed with true contours.

It should be noted that 1 kilometer of standard fiber with a diameter of 125 μm is only sufficient for a shaped body with a volume of 12.27 cm ³ .

For higher volume rates, e.g. for large components, thicker glass fibers (e.g. 300μm) are also available. Commercially available glass fibers have a protective plastic sheath. Depending on where it is used / where it is laid, this plastic coating has certain properties.

This plastic jacket would disrupt the printing process. For this reason, the plastic jacket is removed by means of the peripheral mirror system before the actual 3D printing process, in which the plastic jacket is removed by the targeted introduction of energy, with the glass fiber advantageously also being preheated at the same time.

The result of this pre-treatment of the peripheral mirror system is a glass fiber that is cleaned and at the same time preheated for the switchable nozzle, which is used for the glass extrusion process for 3D glass printing.

Depending on the jacket material, a wide variety of laser types can be used for the glass extrusion process. The basic requirement is the absorption of the wavelength in the plastic jacket.

Likewise, specially manufactured glass fibers can be used directly from the fiber drawing tower for the glass extrusion process. Various material variations can be set here.

Due to this variety of materials of glass fibers that can be used and due to the fast and flexible control of the switchable nozzle by means of laser radiation for the actual extrusion of the glass, a broad portfolio of printable glasses can be achieved with the glass extrusion arrangement and the glass extrusion process.

In order to adapt the glass extrusion process to the respective requirement, certain parameters have to be monitored and controlled.

For example, the laser energy and the clock frequency of the laser beam sources must be adjustable via a distance control (between the dosing element and the build platform). The greater the distance between platform and outlet nozzle the more volume has to be melted.

The distance sensor transmits a value to the control and regulation unit, which regulates the laser sources (energy, cycle time).

Communication between the movement kinematics and the laser system is also required.

Here, too, energy and cycle time must be adapted to the feed movement. If components made of gradient material and/or material combinations are required, the individual laser sources (per chamber) must be switched in such a way that no defects or other artefacts occur.

Active temperature monitoring at the plastification site controls the energy input into the starting material. This allows fluctuations in the system to be detected and compensated for. A defined cooling can be implemented, for example, by means of a flow controller-controlled blowing cooling

Furthermore, the laser power can be adjusted efficiently so that the desired volume is optimally melted. Heat dissipation into the holding system can also be monitored and minimized if necessary.

A control-detection unit, e.g. In this way, a statement about the removal of the cladding layer can be generated.

The advantage of this technical solution in the form of the glass extrusion arrangement and the glass extrusion process is that, starting from a wide variety of glass fibers, they can be used in a variety of ways for 3D glass printing due to the targeted interaction of the peripheral mirror system and switchable nozzle.

Specifically, the following fiber systems can be processed: a) undoped quartz glass

Advantage: no evaporation reactions when melting/welding, very low TEC, high resistance to temperature changes

Disadvantage: high temperature, but not a problem due to the low mass as a result of the fiber diameter b) doped quartz glass fiber

Advantage: lower melting temperature, lower average TE;

Higher refractive index glasses

Disadvantage: uncontrolled dopant evaporation, bubbles (e.g.

_GeO , _P4O10 , _B2O3 , etc. ₎

Dopant Al ₂ O ₃ (or combination of Al ₂ O ₃ -TiO ₂ doping) -> there are no evaporation-endangering effects from Al ₂ O ₃ or TiO ₂ . c) Soft glass (fibers for image transmission, crown/flint glass)

Advantage: very low melting temperature

Disadvantage: high TEC, lower thermal shock resistance, lower strength compared to a)

Another advantage of the glass extrusion arrangement and the glass extrusion process is that the development and use of special fibers and dopings in the form of “printing fibers” that are adapted to the respective printing process is possible, which are taken directly from a fiber drawing tower and introduced into the arrangement and there can be edited with the method.

The invention is explained in more detail below with reference to the schematic drawings and the exemplary embodiments. show:

1: a schematic representation of a first embodiment of the glass extrusion arrangement according to the invention,

FIG. 2: a schematic detailed representation of a section of the glass extrusion arrangement according to FIG switchable, heatable nozzle, which is spatially assigned to a carrier plate,

3: a schematic detailed representation of a section of a second embodiment of the glass extrusion arrangement according to the invention with two switchable nozzles,

4: a schematic detailed representation of a section of a third embodiment of the glass extrusion arrangement according to the invention with a switchable nozzle for the direct melting of an uncoated glass fiber,

5: a schematic detailed representation of a section of a fourth embodiment of the glass extrusion arrangement according to the invention with a switchable nozzle for indirect melting of a preheated glass volume to which an uncoated glass fiber is fed,

Fig. 6a - h: exemplary cross-sectional representations of various uncoated or coated gas fibers,

7: a schematic detailed view of a section of a fifth embodiment of the glass extrusion arrangement according to the invention with the switchable nozzle according to FIG. 4 with online monitoring and

Fig. 8a, b): two exemplary cross-sectional representations of components with a support structure in the form of an axicon (a) and a concave perforated mirror (b)

9: a schematic representation of an arrangement with two glass extrusion arrangements according to the invention.

First embodiment

Structure of the glass extrusion arrangement and direct extrusion (3D glass printing) for the production of a compact, three-dimensional and geometrically defined component (9) in the form of a preform for a structured special optical fiber (e.g. a photonic crystal fiber) from a coated 125 μm standard glass fiber (7) from undoped or Al-doped SiO ₂ using the glass extrusion arrangement The glass extrusion arrangement shown in Figures 1 and 2 for the direct extrusion of a coated glass fiber (7) for the production of compact, three-dimensional and geometrically defined semi-finished products or components (9) comprises:

- a material feed unit (1) as material reserve and preheating unit for heating the coated glass fiber (7) by inductive heating or IR radiation,

- A transport system (2) as an uninterrupted supply of material for the continuous supply of a coated glass fiber (7), in the exemplary embodiment a 125 μm standard glass fiber (SiO ₂ fiber with Al doping between 0 and 20 mol% Al ₂ O ₃ , the melting temperature with undoped SiO ₂ is approx. 1750°C and is reduced by approx. 60K per mol% Al ₂ O ₃ ), which is continuously unwound from a drum within the material feed unit (1),

- A peripheral mirror system (3) with a laser (61), in the example a CO ₂ laser with a wavelength of 10.6 μm, and a peripheral mirror (62) as a stripping and preheating system system, through which the material from the feed unit (1st ) a coated glass fiber (7) is continuously guided/moved through the transport system (2) and is thereby irradiated radially, with a sufficiently high energy input taking place that at a temperature of approx. 400 to 600°C the organic coating (layer thickness in the range of less than 100 nm) is completely removed from the glass fiber (8),

- A switchable nozzle (4) for 3D glass printing, in the exemplary embodiment consisting of molybdenum), which indirectly via an optical system in the form of lenses, e.g. via two lasers (63) in the example a CO ₂ laser radiation (with a Beam power in the kilowatt range) is heated (see Fig. 2) and with which the desired temperature for the transition of the glass fiber (8) into fluid glass (91) is set specifically at T> 1000°C and the material flow is switched on and off can, wherein the nozzle (4) is in the immediate vicinity of a heated platform (42) and on their Outlet opening (41) that discharges the fluid glass (91) and deposits it on the platform (42) in two or three dimensions (with a thickness in the range from 100 μm to several 100 μm [- each depending on the material flow, which can be selected individually by the Laser power is set, and the specified traversing speed], during which the nozzle (4) and the platform (42) are moved relative to one another in the x, y and z direction in a definable manner with the traversing speed, so that the corresponding 3D - Component (9) can arise as intended, and

- A measurement and control system with temperature and movement sensors and computer-based control and regulation technology connected to the lasers (61, 63), the material feed unit (1) and the transport system (2) in order to ensure a constant feed of the glass fiber (7, 8) into the nozzle (4) and monitoring and setting of the required temperature(s) for a constant discharge of liquid glass (91) from the outlet opening (41) of the switchable nozzle (4).

The switchable nozzle (4) is arranged in a process chamber (5) surrounding the heatable platform (42), the platform (42) being positionable in 3 axes (X, Y and Z) by a movement unit. However, it is also within the scope of the invention that the platform (42) can be positioned in 5 axes by a movement unit (not shown in the figures).

Furthermore, a gas flow controller can be provided (also not shown in the figure), which can direct cooling air to the heated platform (42) in a controlled manner.

The peripheral mirror system (3) is arranged outside of the process chamber (5), with the coated glass fiber (7) to be extruded passing through the transport system (2) from the material feed unit (1) through the peripheral mirror system (3) via the inlet opening (51) of the Process chamber (5) is introduced into the switchable nozzle (4) for extrusion via the outlet opening (41). These subsystems can be controlled and operated simultaneously with precisely controlled parameters by a control and regulation unit in order to use the glass extrusion system to directly produce compact, 3-dimensional and geometrically defined semi-finished products and components (9) made of glass using a continuously supplied, commercially available and to enable optionally sheathed (coating) glass fiber.

In the peripheral mirror system (3), one or more lasers (61) are used to strip the coated glass fiber (7) (see FIG. 2), in which the continuously fed glass fiber (7) is irradiated radially and thus a sufficiently high Energy is introduced in order to completely remove the cladding of the glass fiber (7) in the form of the organic coating (e.g. in the form of acrylate) from this in order to arrive at a cladding-free glass fiber (8) which is continuously fed into the switchable, heatable nozzle ( 4) is introduced to melt.

In addition and advantageously, it can be provided that a detection system ensures the removal of the organic emissions that arise during this stripping (not shown in FIGS. 1 and 2).

The material feed unit (1) is advantageously applied to heat the glass fibers (7, 8) by inductive heating or IR radiation.

The actual intensive preheating of the glass fiber (7, 8), however, takes place through the scope spiegelsy system (3).

As shown in Fig. 2, the switchable nozzle (4) is heated indirectly via laser beams from at least one laser (63), in the example from two lasers (63) for CO ₂ laser radiation, so that the stripped glass fiber (8) in this is melted.

Because the nozzle (4) can be switched quickly by means of the laser-generated temperature control, the desired glass viscosity is set in a targeted manner, monitored by sensors and constantly adjusted to the desired value in the control loop (not shown in FIGS. 1 and 2). Temperature is readjusted, and it is also possible to switch the material flow of the glass fiber (8) melted to the fluid glass (91) on and off for 3D printing on the heatable platform (42).

The transport system (2) conveys the 125 μm standard glass fiber continuously into the peripheral mirror system (3) and the stripped glass fiber (8) into the following switchable nozzle (4) so that the still coated glass fiber (7) can be removed from the material feed unit (1). uninterrupted to the place of extrusion at the outlet opening (41) of the switchable nozzle (4) and fluid glass (91) is always ready for the 3D glass printing process.

The measuring and control system in the form of the control and detection unit (not shown in Figures 1 and 2) serves to control the entire glass extrusion process through the individually controllable subsystems of the glass extrusion arrangement for the constant material input and output by means of the transport system (2), a temperature monitoring unit and movement and distance sensors (not shown in Figures 1 and 2) being coupled in at the same time and connected to the control and regulation system (also not shown in Figures 1 and 2) of the at least one laser (63), [in the exemplary embodiment two] of the switchable nozzle (4) and the laser (61) of the peripheral mirror system (3) as well as the material feed (1) are connected in order to design the entire 3D printing process in a defined and continuous manner, so that the sequential placement of individual layers a preform as a 3-D molded body [= component (9) in Fig. 1] with typical dimensions from 20 mm to 50 mm in height or diameter with definable structures.

The individual layers of the 3D shaped body [=component (9)] are deposited on the heated platform (42), with the preheating temperature being individually selected depending on the type of glass in order to avoid thermally induced stresses as a result of high cooling rates. For this purpose, the thermal shock resistance (TWB) of the respective Observe the type of glass, for example when using undoped or Al-doped SiO ₂ as follows:

The 3-D shaped body [=component (9) in FIG. 1] is then separated from the platform (42) and the surface is smoothed, for example, with laser polishing.

A special optical fiber, e.g. in the form of a photonic crystal fiber with cavities of different sizes (e.g. bandgap fibers, anti-resonant fibers, evanescent sensor fibers with large internal cavities) can be produced from this preform in an adapted fiber drawing process.

Second embodiment

Direct extrusion (3D glass printing) of a coated glass fiber (7) in the glass extrusion arrangement for the production of a dense and transparent optical semi-finished product or optical component (9) made of borosilicate glass

In this exemplary embodiment, an already established coated glass fiber (7) made of high-melting glass is used as the starting material (although low-melting glasses could also be used). The diameter of the fiber (7) used in this exemplary embodiment is typically 250 μm (however, the nozzle geometry and the extrusion parameters can also be adapted for other fiber dimensions).

The glass fiber (7) is continuously unwound from a drum by means of the controlled fiber transport system (2) (designed as a roller capstan) and fed to the glass extrusion arrangement explained in the first exemplary embodiment at a defined feed speed. In the peripheral mirror system (3), the fiber coating is first removed without leaving any residue. For this purpose, laser radiation is homogenized in the peripheral mirror by multiple reflections and the glass fiber is thereby irradiated peripherally. The coated glass fiber (7) is heated to temperatures of approx. 400 - 600°C and the coating is thereby removed without leaving any residue. In this step, the fiber material is also preheated as an offset temperature for the subsequent extrusion step.

The stripped and preheated glass fiber (8) is now fed to the switchable nozzle (4). The nozzle (4) is heated indirectly by means of energetic radiation, in this exemplary embodiment CO ₂ laser radiation, and heats the fiber (8) made of high-melting glass until it has reached the required viscosity. A laser (63) with a beam power in the medium kilowatt range is used for this purpose, which is sufficient to heat the fiber (8) to temperatures of T>1000°C. The material flow can be varied or stopped via the individually selectable laser power. In connection with the traversing speed, the layer thickness of the deposited fluid glass (91) can be precisely controlled and varied over a wide range from D<100 μm to several 100 μm. Analogously, the structural width of the fluid glass (91) can also be varied.

The fluid glass (91) (=extrudate) is deposited on the heated platform (42), with the preheating temperature being selected individually depending on the type of glass in order to avoid thermally induced stresses as a result of high cooling rates. For this purpose, the thermal shock resistance (TWB) of the respective glass type is taken into account, for example when using borosilicate glasses of this exemplary embodiment as follows: The component (9) is built up as a 3D shaped body with typical dimensions of 20 mm to 50 mm in diameter or height and variably realizable structures via the sequential deposition of individual layers.

The component (9) is then mechanically separated from the platform (42) and removed from the process chamber (5). The outer surface is smoothed using a laser polish and then slowly cooled down in a separate, temperature-controlled oven.

Third embodiment

Direct extrusion (3D glass printing) of a coated glass fiber (7) from high-melting glass in the glass extrusion arrangement for the production of a glass body (9) with inner contours

In the third exemplary embodiment, the glass fiber with the sheathing (7) is fed in analogously to the first and the second exemplary embodiment.

In this exemplary embodiment, the glass fiber with the casing (7) is stripped by one or more mechanical cutters, which remove the casing from the glass fiber (7) with as little residue as possible by means of a peeling process.

The stripped and preheated glass fiber (8) is then fed to the switchable nozzle (4). The nozzle (4) is heated directly or indirectly by means of energetic radiation and heats the fiber (8) until the required viscosity is reached. In this exemplary embodiment, a laser system (63) with a beam power in the medium kilowatt range is used, which is sufficient to heat the 3D printing fiber to temperatures of T>1000°C.

The material flow of the fluid glass (91) can be varied or stopped via the individually selectable laser power. In connection with the traversing speed, the layer thickness of the on the heated platform (42) (preheating temperature is selected individually depending on the type of glass in order to reduce thermally induced stresses due to high To avoid cooling rates) deposited material can be precisely controlled and varied over a wide range from D < 100 microns to several 100 microns. The structure width of the material can be varied analogously.

The component is built up as a 3D shaped body with typical dimensions of 20 mm to 50 mm in height and variably realizable structures by sequentially depositing individual layers from the fluid glass (91).

In order to be able to realize inner contours or steep transitions in the 3D shaped body (93), support structures (100) are also built up in the resulting cavities and walls during the layered construction on the platform (42) (shown in Figures 8a and 8b) .

The support structures (100) can be produced from different preform structures (see FIG. 6) of the same type or different materials.

After the construction process and cooling of the 3D shaped body (93), it is separated from the platform (42) and removed from the process chamber.

If a dissimilar material is used as the support structure, the separation process can also take place chemically. For this purpose, the 3D shaped body (93) is placed in a KOH bath, as a result of which the dissimilar material, which has a significantly higher etching rate than the 3D shaped body (93), separates from it.

If a high surface quality and/or component shape accuracy is to be achieved, the additively manufactured 3D shaped body (93) is subjected to a grinding and/or polishing process.

In order to achieve parts with a high level of homogeneity, further process steps such as pressure glazing and fine cooling can be carried out. Fourth embodiment

Direct extrusion (3D glass printing) of a coated glass fiber (7) from high-melting glass in the glass extrusion arrangement for the production of a glass body (9) in the form of a gradient component

In a fourth exemplary embodiment, the coated fiber (7) is fed in and the cladding is removed in the same way as in exemplary embodiments 1, 2 or 3.

In contrast to the exemplary embodiments 1, 2 or 3, at least two switchable nozzles 4a and 4b are used in the fourth exemplary embodiment (shown in FIG. 3).

Both nozzles (4a and 4b) transport two fibers made of different glass materials with two different properties (91a and 91b).

Both nozzles (4a and 4b) can work simultaneously or sequentially, the component platform (42) and the two nozzles (4a and 4b) being moved relative to one another in the x, y and z direction by a drive system not shown in FIG.

In this exemplary embodiment, a gradient component (9a; 9b) is built on the construction platform (42) with two different refractive indices n1 and n2.

Any graduated glass with different properties (e.g. different refractive indices) can be produced with this arrangement.

If the refractive index inside the component (9b) is high (e.g. n2 = 1.8) and lower in the outer area (e.g. n1 = 1.5), then gradient glasses can be used for preforms (for fiber drawing) or conversely, optical disks for the correction of spherical aberrations can also be manufactured. In order to generate fewer internal stresses in the component, it is advantageous to set temperatures above 450° C. in the process chamber (5) and to subject the component to controlled cooling T(t) after the construction process. Also, the linear expansion coefficients of the different glass materials should not differ too much.

Working with an arrangement of several nozzles (4) as shown in FIG. 3 also allows the use of a different support material. If this support material (ULE) has a different etching behavior than the base material (quartz glass), the support geometry can also be removed after the construction process in an acid or lye by deposits in it. It is advantageous to use a 45% KOH solution. (8 μm/min removal for quartz glass and 1 μm/min removal for ULE).

Fifth embodiment

Extruder arrangement [(switchable nozzle (4)] for the direct and indirect laser beam melting of a glass fiber without a coating (8) in the glass extrusion arrangement

In the case of the switchable nozzles (4) (= extruder arrangements) shown in Figures 4 and 5, depending on the diameter of the glass fiber used without sheathing (8) (typically 150 μm to 1 mm), glass strands (91) are in the dimensions of the fiber diameter (through the glassy molten state increased by a factor of 1.15) on the platform (42).

The glass fiber is fed without sheathing (8) to the switchable nozzle (4) via take-off rollers of the transport system (2).

The glass fiber (8) is transferred coaxially into the molten area in a very short time by a laser ring mirror, so that the viscosity of the material of the glass fiber (8) drops abruptly in that viscosity-temperature range (approx. 1-3 dPas) where the material is converted into a good flowable state. The softened and free-flowing volume of material can thus pass through the nozzle (4) very quickly and be deposited on the platform (not shown in FIG. 4). A pulsed CO ₂ laser is preferably used for the partial melting process. With pulse lengths in the ps-ms range of the radiation from the laser (63), a very metered supply of fluid glass (91) can thus take place.

This is a prerequisite for the process control in order to be able to quickly stop and restart the material feed of fluid glass (91) when there is a change in contour during the construction process, and also for the use of several extruders in a construction process (see fourth exemplary embodiment and FIG. 3) .

In the extruder arrangement for indirect melting of a preheated glass volume, shown in FIG. 5, the glass fiber without a jacket (8) is conveyed into a heating container of the switchable nozzle (4) in the form of an enlarged material storage reservoir.

In this enlarged material reservoir (heating vessel), the introduced glass volume is brought to a pre-extrusion temperature by a heating source, preferably heating strips (52) in the form of resistance-heated strips (see FIG. 5). Depending on the type of glass used, a typical preheating range can be between 400 °C and 1,500 °C.

At the end of the heating container, the glass volume has a viscosity between 4 - 10 dPas, for example. The radiation from the laser (63) now applies a defined laser energy to a radiation converter (72).

The radiation converter (72) has a very good transmission of the optical radiation into thermal energy in order to bring the provided glass volume very quickly into a viscosity-temperature range (approx. 1-3 dPas) where the material [the fluid glass ( 91)] is converted into a readily flowable state.

In this extrusion arrangement, a significantly larger glass strand can be discharged due to the preheated glass volume provided. A switchable nozzle (4), in this embodiment with a variable nozzle diameter (41), can the diameter of the fluid glass (91) can be adjusted accordingly in a range from 200 μm to several millimeters.

Sixth embodiment

Arrangement for online-monitored and online-controlled glass exit

The arrangement shown in FIG. 7 for the online-monitored and online-controlled outlet of fluid glass (91) as part of the overall glass extrusion arrangement has a temperature measuring device (70) in the area at the outlet opening (41) of the switchable nozzle (4), preferably a pyrometer.

The temperature of the fluid glass (91) is measured online with this pyrometer. The measured, calibrated temperature signal is used to determine the viscosity of the fluid glass (91) in order to control the outlet of the fluid glass (91) in a controlled operation.

The power of the lasers (63) and the two fiber feed devices (73) of the transport system (2) are controlled as a function of the measured temperature.

This control circuit ensures that a homogeneous flow of glass can be ensured throughout the entire construction process.

Seventh embodiment

Arrangement with multiple extruders for additive processing of sections of provided solids

A disadvantage of additive manufacturing can be the relatively long processing times when dealing with large-volume or simple geometric shapes. This disadvantage is overcome by the hybrid production concept with an arrangement as shown in FIG. 9, for example.

The starting point is the provision of a prefabricated blank, semi-finished product or finished component (94a). the Areas (94b) that have a more complicated shape and can only be produced to a limited extent or not at all by conventional separating processes such as milling and grinding are built up layer by layer by the first switchable nozzle (4a).

Such typical contours, as shown in FIG. 9 using the example of internal cooling, include, for example, internal contours, undercuts, thin webs, contours with a high aspect ratio (the ratio of height to width) or special free-form surfaces.

In order to achieve an exact transition between the two shaped bodies (94a) and (94b), it is necessary to reference and align the axis systems X,Y,Z and X'Y',Z'. This is done with the help of the referencing unit (101), which is preferably designed to be optical and/or tactile.

The processing sequence includes the following steps:

- Positioning and aligning the component (94a) on the construction platform (42),

- Referencing of the component position with the extruder systems, [only shown here in Fig. 9, the switchable nozzles (4a and 4b) with the transport system (2) and glass fiber with sheathing (7)],

- heating of the component (94a) to the required process temperature,

- Start the printing process with the first switchable nozzle (4a),

- Layered structure of the area (94b),

- After completion of the additive process, the component (94) is cooled with a temperature-time function known to those skilled in the art, also referred to as fine cooling.

If the areas (94b) to be built up are relatively small compared to the component volume (94a), these connection areas (joining zones) (95) can be partially heated to the required process temperature by a laser beam (64). In this case, the heating of the entire component volume (94a) in the process chamber can be omitted. The joining zone (95) shown in FIG. 9 represents a peripheral area of the component (94a), which is quasi-simultaneously through the Beam deflection between the maximum areas (64a) and (64b) is heated.

The transition between two joining partners with different linear expansion coefficients is often difficult and sometimes not even possible.

According to the present invention, glass transition solders are used to solve this problem. In the arrangement according to FIG. 9, a second switchable nozzle (4b) is additionally used for this purpose, which discharges a second glass strand with a glass transition solder. If a zone with glass transition solder (94c) is now applied between the component (94a) and the area (94b) to be produced additively using (4b), components (94) made of different materials can also be connected. For example, a material combination of a glass ceramic (94a) and a silica glass (94b) is also possible. A metal-glass composite can also be built up with the available glass transition solders.

There are often production-related defects that lead to breakouts, edge damage or larger surface defects and thus make glass substrates and finished components unusable. In the case of larger components, e.g. telescope mirrors, this leads to considerable material losses.

With the arrangement according to FIG. 9, it is possible to heal such defects by applying a partial layer (94d) with the switchable nozzle (4a) [the processing is not shown in the picture]. In this case, material (91a) of the same type as component (94a) is preferably used. A subsequent finishing process by fine grinding and polishing of the area (94d) is required in most cases.

The arrangement according to FIG. 9 makes it possible to combine the advantages of subtractive manufacturing (grinding, lapping, polishing) and additive manufacturing. On the one hand, prepared semi-finished products can be used as components (94a), which are finished after the additive process stage by form grinding and polishing to form the complete component (94). On the other hand, you can Components are inserted into the extrusion system after the complete subtractive process stage in order to build up or add additional contour elements or to repair component defects.

The advantage of the provided technical solutions of the glass extrusion arrangement and the glass extrusion process is that by means of the method using the glass extrusion arrangement, both standard glass fiber systems with a complete or partial sheathing and standard glass fiber systems without sheathing are converted into semi-finished products and components of all kinds using 3D glass printing so that these products can be put to a wide variety of uses or further processing.

The glass extrusion arrangement and the glass extrusion process are particularly interesting for the production of modified glass fibers (e.g. for image transmission), of components or semi-finished products made of glass.

In the process, for example, commercially available and optionally coated glass fibers are fed in continuously. The process can also be used to process both low-melting glass systems (Tg << 1000°C, e.g. for glass fibers for image transmission) and higher-melting systems (Tg >> 1000°C).

Another positive aspect of the present technical solution is that the glass extrusion arrangement and the method using this arrangement can be used for different, fusible fiber systems (in addition to the most diverse types of glass fibers, such as undoped or doped quartz glass fibers, soft glass fibers). As a result, the scope of the invention is not tied to starting materials in the same way as other methods which can only use special starting materials.

All of the features presented in the description, the exemplary embodiments and the following claims can be be essential to the invention individually or in any combination with one another.

Reference List

1 - material feeding unit

2 - transport system

3 - perimeter mirror system

4 - switchable nozzle

4a - first switchable nozzle

4b - second switchable nozzle

41 - outlet opening

42 - platform

5 - process chamber

51 - entrance opening

52 - heating tapes

61 - laser of the perimeter mirror system

62 - perimeter mirror

63 - Laser of switchable nozzle

64 - laser beam

64a - first maximum area

64b - second maximum area

65 - scanning mirror

7 - fiberglass with sheath

70 - temperature gauge

72 - radiation converter

73 - fiber feed device

8 - fiberglass without sheath

9 - component

9a; 9b - components with different refractive indices

91 - fluid glass

91a - first property of the fluid glass

91b - second property of the fluid glass

93 - 3D molding

94 - component 94a - finished component (glass ceramic)

94b - area with complicated shape (fused silica)

94c - glass transition solder

94d - area built up in layers 95 - connection area (joining zone)

101 - referencing unit

100 - support structure n1 - first refractive index n2 - second refractive index

X, Y, Z - spatial axes x, y, z - directions in 3D space

Claims

patent claims

1. Glass extrusion arrangement for the direct extrusion of a glass fiber (8) or a coated glass fiber (7) for the production of a compact, 3-dimensional and geometrically defined semi-finished product or component (9) made of glass, which several, individually controllable subsystems in the form

- a peripheral mirror system (3),

- a switchable, heatable nozzle (4) with an outlet opening (41),

- And a transport system (2), characterized in that

• the nozzle (4) is arranged in a process chamber (5) surrounding a heatable platform (42),

• the nozzle (4) and the platform (42) can be positioned in relation to one another in 3 axes in the x, y and z directions by means of a movement unit,

• the peripheral mirror system (3) is arranged outside the process chamber (5), with the glass fiber (7, 8) to be extruded from a material feed unit (1) continuously by means of the transport system (2) through the peripheral mirror system (3) through an inlet opening (51 ) of the process chamber (5) can be inserted into the nozzle (4) for melting and subsequent extrusion of fluid glass (91),

• through the outlet opening (41), the fluid glass (91) for generating the component (9) in the direction of the platform (42) can be removed and

• the subsystems can be controlled and operated simultaneously and precisely by a control and regulation unit, wherein

• the peripheral mirror system (3) comprises at least one controlled laser (61) and a peripheral mirror (62) with a peripheral mirror system axis and an optical system which, in the operating state, emits a beam of laser light perpendicular to the peripheral mirror system axis Circumferential mirror (62) couples in that, after multiple reflections, it impinges on the glass fiber (7) to be treated, the axis of which runs in the same direction inside the peripheral mirror (62) as the peripheral mirror system axis.

• the nozzle (4) can be irradiated with at least one controlled laser (63) for the purpose of heating, with a thermocouple monitoring the heating temperature when heating the nozzle (4) in the operating state so that the glass fiber (8) heated by the laser light is above its melting point is present as a free-flowing fluid in the nozzle (4) and can flow out of the outlet opening (41) in the direction of the platform (42), and

• the nozzle (4) can be switched by quickly switching the laser (63) on and off, in that this rapid switching on and off can very quickly generate a change between the heating and cooling phases.

2. Glass extrusion arrangement according to claim 1, characterized in that the transport system (2) comprises at least one controllable feed motor, the feed motor controlling the volume rate of the delivered fluid glass (91) via the feed of the glass fiber (8) when the transport system (2) is in operation .

3. Glass extrusion method for the direct production of compact, three-dimensional and geometrically defined semi-finished products and components (9) made of glass, using a glass extrusion arrangement according to claim 1 or 2, wherein the method is a generative printing method in which a continuously supplied, commercially available and Optionally coated glass fibers (7, 8) are passed through the peripheral mirror system (3) by means of the transport system (2), preheated in the process and completely freed of any coating that may be present and then through the switchable, heatable nozzle (4) within the process chamber (5). fluid glass (91) is melted and extruded, in which the fluid glass (91) via the outlet opening (41) of the nozzle (4) in the direction of the platform (42) is dispensed and the nozzle (4) and the platform (42) are moved relative to one another in a predetermined manner in the x, y and z direction, with the volume rate of the dispensed fluid glass (91) being determined by the advance of the fluid glass (91) conveyed by the transport system (2nd ) conveyed glass fiber (8) and the diameter of the outlet opening (41) of the switchable nozzle (4) is controlled, so that predetermined amounts of glass in the fluid state are dispensed in portions onto the heatable platform (42), on which they then cool and become the component (9) solidify, the material of the glass fiber (7, 8) comprising both low-melting and higher-melting glass systems.

4. The method according to claim 3, characterized in that by the control and regulation unit

- the laser (61) is switched quickly and the associated dosing of the energy input in the peripheral mirror system (3) is carried out in order to set the viscosity of the glass fiber (7, 8) in a defined manner before it enters the nozzle (4) and to seal any existing sheathing of the to completely remove glass fiber (7),

- the temperature is controlled when the nozzle (4) is heated by means of the at least one controlled laser (63), with at least one temperature sensor monitoring the heating temperature when the switchable nozzle (4) is heated, with feedback, and

- the feed motor of the transport system (2) for feeding the glass fiber (7, 8) is controlled with feedback from at least one temperature sensor and at least one movement sensor, with the volume rate of the fluid glass (91) being dispensed being controlled via the feeding of the glass fiber (8). will.

5. The method according to claim 4, characterized in that when the nozzle (4) is heated by means of the at least one controlled laser (63), the focal spot diameter and thus the intensity of the laser is changed by varying the distance between the nozzle (4) and the laser (63). (63) is varied to set the volume of the Glass fiber (8) is melted in the nozzle (4), which should be available for the 3D printing of the fluid glass (91) on the platform (42).

6. The method according to one or more of claims 3 to 5, characterized in that in the layered structure of the component (9) consisting of the fluid glass (91) which is placed on the platform (42) and cooled there, in addition Support structures (100) are also built up with a 3D shaped body (93), in which the layer thickness of the structure is adjusted by changing the power of the laser (63) of the switchable nozzle (4) and the traversing speed of the movement of the nozzle (4) and the platform (42) is varied to each other in the range of <100 microns to several 100 microns.

7. The method according to one or more of claims 3 to 6, characterized in that at least two switchable nozzles (4a and 4b) deposit different fluid glasses (91) with different properties (91a and 91b) on the platform (42).

8. The method according to claim 10, that the different properties (91a and 91b) different refractive indices (n1 and n2) for the construction of optical structures or different base and support material for the construction of the 3D shaped body (93) and the support structure (100) are.