US-12623285-B2 - Filter device for an additive manufacturing device

US12623285B2US 12623285 B2US12623285 B2US 12623285B2US-12623285-B2

Abstract

Disclosed is a filter system for an additive manufacturing device for purifying a process gas of the additive manufacturing device wherein, in order to purify a volume of process gas during operation, the filter system has at least one permanent filter. The permanent filter is configured so as to be thermally stable in a manner such that during operation, the permanent filter is stable at a temperature of more than 110° C. Further disclosed is an additive manufacturing device as well as an additive manufacturing process.

Inventors

Ulrich Kleinhans
Philip Stroebel

Assignees

EOS GMBH ELECTRO OPTICAL SYSTEMS

Dates

Publication Date: 20260512
Application Date: 20210602
Priority Date: 20200617

Claims (10)

1 . An additive manufacturing device for manufacturing a component in an additive manufacturing process, the additive manufacturing device comprising: a process chamber; a feed system for introducing a build material into the process chamber in layers; an irradiation unit for selectively solidifying the build material in the process chamber; and a filter system for purifying a process gas of the additive manufacturing device, the filter system comprising: a permanent filter that is regenerable and configured to remain installed during repeated operating cycles; and a cleaning arrangement configured to clean the permanent filter in situ by a reverse-flow cleaning gas pulse to remove collected particles.
2 . The additive manufacturing device of claim 1 , wherein the filter system comprises a filter chamber having a transparent region, and an energy input source configured as a radiant heating system disposed to couple heat radiation into the filter chamber through the transparent region to heat particles entrained in the process gas.
3 . The additive manufacturing device of claim 1 , wherein the permanent filter is configured to be thermally stable at a temperature of more than 150° C.
4 . The additive manufacturing device of claim 1 , wherein the permanent filter comprises a metal filter and/or a ceramic filter and/or a glass wool filter, wherein the metal filter is constructed from at least one corrosion-resistant steel and/or from a nickel-based alloy and/or from copper and/or from mixtures or alloys thereof.
5 . The additive manufacturing device of claim 1 , wherein a mesh size of a filter material of the permanent filter is between 0.5 μm and 30 μm.
6 . The additive manufacturing device of claim 1 , wherein the permanent filter comprises a support structure designed to support a filter surface of the permanent filter, wherein the support structure runs parallel to a filter material of the permanent filter, in at least a subarea on a dirty gas side and/or on a clean gas side of the permanent filter, or is integrated into the permanent filter.
7 . The additive manufacturing device of claim 1 , wherein a diameter of filaments and/or wires which form a filter material of the permanent filter is less than 20 μm, wherein a diameter of wires that form a support structure is more than 100 μm in thickness.
8 . The additive manufacturing device of claim 1 , wherein a dirty gas side of the permanent filter coming into contact with the process gas to be purified has a meandering pleated surface, at least in regions, wherein folds are disposed in the meandering pleated surface in order to form a pleated surface of the dirty gas side, wherein the folds for pleating are folds in a continuous fabric or are welded together and/or bonded together.
9 . The additive manufacturing device of claim 1 , wherein the permanent filter is disposed in the filter system in a manner such that a dirty gas side coming into contact with the process gas to be purified is an outer surface of the permanent filter and/or wherein the permanent filter is disposed in the filter system in a manner such that the dirty gas side coming into contact with the process gas to be purified is an inner surface of the permanent filter.
10 . The additive manufacturing device of claim 1 , wherein the permanent filter is configured in a manner such that an oxidation reaction of particles present in the permanent filter can be initiated, wherein the permanent filter is coupled to an energy input source, and a metal fabric or a portion of a metal fabric of the permanent filter constitutes a heating element.

Description

TECHNICAL FIELD OF THE INVENTION The present invention relates to a filter system for an additive manufacturing device, to an additive manufacturing device with a filter system of this type, as well as to a process for the additive manufacture of a component. BACKGROUND OF THE INVENTION When producing prototypes and now also in mass production, additive manufacturing processes are becoming increasingly relevant. In general, the term “additive manufacturing processes” should be understood to mean those manufacturing processes in which, as a rule based on digital 3D construction data, a manufactured product or component is built up by depositing material. Building is usually accomplished by applying a build material in layers and selectively solidifying it. A synonym for additive manufacturing which is often also employed is the term “3D printing”; the production of models, samples and prototypes using additive manufacturing processes is often described as “Rapid Prototyping” and the production of tools is described as “Rapid Tooling”. Selective solidification of the build material is often carried out by repeatedly applying thin layers of the usually powdered build material one over another and, by means of spatially restricted irradiation, for example by means of light or heat radiation, solidifying it at those positions intended to form part of the manufactured product to be produced following manufacture. Examples of processes operating by irradiation are “selective laser sintering” or “selective laser melting”. The powder particles of the build material are partially or completely melted during the course of solidification with the aid of the energy introduced locally to that position by the irradiation. After cooling, these powder particles are then bonded together into the form of a solid body. In production of this type, it is frequently necessary for a process gas to be conveyed through the process chamber (in particular with a fan) for the purposes of cooling or discharge. The process gas which emerges in this regard usually entrains particles of the build material and/or particles which arise from the process, in particular metal condensates when metallic build materials are used, some of which are highly reactive and can react even at room temperature with small quantities of oxygen in the air, with the release of a great deal of heat. In order to prevent contamination of the process gas with the particles, for example in order to counteract gradual contamination of the process chamber and/or the fan, it is necessary to filter the process gas after it leaves the process chamber. However, because of the high reactivity of the particles, in the region of filters on which the particles which are entrained in the process gas collect, uncontrolled filter fires or dust explosions may occur. This risk is higher when, for example, a corresponding filter chamber is opened in order to exchange the filter or filters, whereupon the probability of reaction is increased because of the associated increased supply of oxidizing agents, for example oxygen from the air. SUMMARY OF THE INVENTION An objective of the present invention is to provide an improved or alternative filter system or a manufacturing device provided with a filter which enables the filter to be removed safely when exchanging the filter in an additive manufacturing device. In this regard, the invention is concerned with the field of additive manufacturing, wherein this manufacturing is carried out in a (closed) process chamber through which a process gas is conveyed and which is then filtered. The term “process gas” as used here should be understood to mean a gas which is discharged from a process chamber, in particular sucked out, and which, depending on the production process, may also comprise or be an inert gas. In the process gas, both unsolidified fractions of a build material as well as by-products of the process such as condensates, for example metal condensates, may be present. Components of this type which are entrained in the process gas are amalgamated into the term “particle”. A filter system in accordance with the invention for an additive manufacturing device serves to purify a process gas of the additive manufacturing device. In order to purify a volume of process gas during operation, the filter system has at least one (dimensionally stable) permanent filter which is preferably configured so as to be thermally stable, preferably combustion resistant, in a manner such that during operation, the permanent filter is stable at a temperature of more than 110° C. In the context of the invention, the term “permanent filter” (or durable filter) should be understood to mean filters which, in contrast to the usual filter models, can stay in place for many (multiple) cycles and/or permanently during the operation of the additive manufacturing device. To this end, a permanent filter is cleaned after a certain time, i.e. the filtrate is remove