DE102021131219A1 - Device for debinding a green body - Google Patents

Abstract

The invention relates to a device for debinding a green body (1). The device comprises a debinding station (2) which includes a heatable debinding chamber (20). The device also includes an acid reservoir (3), which is fluidically connected to the debinding chamber (20) and is designed and provided to receive an acid (4) required for debinding and to the debinding chamber (20) for a debinding process of the green body (1st ) to provide required acid in gaseous state. The device also includes heating means (5) for heating the acid reservoir (3) independently of the debinding chamber (20). Control means (10) are provided, which are provided and set up to control the amount of acid (4) required for debinding, which the acid reservoir (3) provides to the debinding chamber (20), by adjusting the temperature of the heating means (5). to control. The invention also relates to a method for debinding a green body (1).

Description

The invention relates to a device for debinding a green body.

A green body or green body is a component that consists of a powdery material, such as a metal or ceramic powder, which is held in shape by a binder. The green body is an intermediate product which, although it has all the geometric properties of the component to be produced, requires further processing steps. Normally, in a further step, the typically organic binder is dissolved out of the green body and the part is then sintered. Debinding turns the green body into a so-called brown body or brown compact, which in turn becomes the finished component through sintering. The sintering is associated with a shrinking process.

Manufacturing methods known as “Fused Deposition Modeling” (FDM) or “Fused Filament Fabrication” (FFF) are known, in which a filament is manufactured in layers in a printer unit to form a metallic or ceramic printed part, which forms a green body. However, a green body can also be provided by other types of production, for example by metal powder injection molding. In any case, the binder is removed from the green body by debinding.

It is known to use binder systems made from polyoxymethylene (POM) or other organic substances as binders. Catalytic binder removal is known for removing binder from such a green body, in which the green body is treated in a gaseous, acidic atmosphere of hydrogen halides, formic acid or nitric acid at elevated temperature. Corresponding methods are, for example, in EP 0 413 231 A1 , the EP 2 686 286 A1 and the CN106270506A1 described, to which reference is made in this respect. An example of a catalytic process is the so-called Catamold® process from BASF SE, in which nitric acid and nitrogen form a gaseous, acidic atmosphere that is used in childbirth.

A catalytic debinding with oxalic acid is from the WO 94/25205 A1 known.

The debinding process typically involves two phases. In the first phase, the binder is largely removed in a gaseous, acidic atmosphere, with a residual binder remaining, which is then thermally decomposed in the sintering furnace in a second phase. The first phase takes place in what is known as a debinding station, which is suitable for receiving the gaseous acid and can be heated so that there are no cold spots where the acid could condense.

A disadvantage of known debinding systems is that it is difficult to dose the exact amount of acid required for debinding.

Accordingly, the object of the invention is to provide a device for effective debinding of a green body.

This object is achieved by a device having the features of patent claim 1 and a method having the features of patent claim 17 . Developments of the invention are specified in the dependent claims.

Accordingly, the present invention considers a device for debinding a green body. The device includes a debinding station with a heatable debinding chamber for debinding the green body and an acid reservoir. The acid reservoir is fluidically connected to the debinding chamber and designed and provided to receive an acid required for debinding and to provide the debinding chamber with the acid in the gaseous state required for a debinding process of the green body.

According to the present invention, the apparatus further comprises heating means for heating the acid reservoir independently of the debinding chamber. In this case, control means are provided which are set up to control the quantity of acid required for debinding, which the acid reservoir makes available to the debinding chamber, by adjusting the temperature of the heating means.

The invention is based on the idea of providing the acid required for the debinding process in a separate acid reservoir, with the acid provided for the process being able to be suitably controlled via the temperature of the acid reservoir, which can be set independently of the temperature of the debinding chamber. In this way, the temperature of the acid reservoir can be used to precisely set the amount of acid that is converted into a gaseous state and can flow into the debinding chamber via the fluidic connection and is thus made available for debinding the green part.

Here, the heating means of the acid reservoir and their control of the heat input or the temperature of the acid can be adjusted in such a way that a controlled phase transition of the acid takes place. The heating means for heating the acid reservoir, which are arranged independently of the debinding chamber, in conjunction with the control means, enable improved dosing of the acid supplied for debinding, regardless of the temperature in the debinding chamber.

Thanks to the improved dosing of the acid, the debinding process can be controlled and carried out with maximum effectiveness, so that, for example, debinding that is too rapid, which could damage the green body with inclusions, is ruled out. At the same time, the separation of the debinding chamber and the acid reservoir increases safety, since the possibility of contact with the acid, for example when inserting the green body into the debinding chamber, is reduced.

Another advantage associated with the invention is that no mechanically moving parts are necessary to provide the required amount of gaseous acid.

Any connection that enables gas exchange between the acid reservoir and the debinding chamber is considered to be a fluidic connection within the meaning of the present invention.

The green body consists of a metal and/or ceramic powder mixed with a binder. For example, the green body can comprise a printed part which is produced in layers from a filament using a 3D printing process. The filament consists of a metal or ceramic powder mixed with a binder. In a 3D print, for example, a filament is used that has a metal powder made of copper, stainless steel or tempered steel. Examples of materials are 17-4PH or 316L stainless steels and 42CrMo4 heat-treatable steels. For the use of ceramic powder, exemplary embodiments provide that the ceramic powder consists of aluminum oxide or zirconium oxide or generally an oxide ceramic, nitride ceramic or carbide ceramic or a mixture of such ceramics.

Alternatively, the green body can be an injection molded part, for example, in which a binder is used to connect the metal and/or ceramic powder during the injection molding process. Suitable materials that form the metal powder or ceramic powder are, for example, in EP 2 686 286 A1 described. Alternatively, the green body can also have been manufactured in a further primary shaping process, in particular in a primary shaping process from a liquid, plastic or pulpy state.

One embodiment of the invention provides that the heating means have separate heating elements for different heating zones of the acid reservoir, with the acid reservoir and the acid contained in it being able to be heated to different degrees in the different heating zones. It can be provided that the different heating zones are arranged vertically one above the other. This aspect of the invention allows to increase and refine the control effect provided by the heating means. For example, only the uppermost heating zone is heated when the amount of gaseous acid to be provided is only small, and additional heating zones are connected when the amount of acid is to be increased.

An advantageous embodiment provides that the acid is present in the acid reservoir at room temperature (20° C.) as a solid which changes directly into the gaseous state from a sublimation point. The heating means are controlled by the control means, for example, in such a way that the temperature of the acid reservoir is above or below the sublimation point. As a result, the amount of gaseous acid provided can be controlled in a particularly simple and effective manner. The acid can also be handled and transported particularly well in its solid form. In one embodiment, the acid is present in granular form in the acid reservoir.

In one embodiment, oxalic acid is used as the acid. Oxalic acid has a low hazard class compared to other acids. For a sublimation of the oxalic acid, it is provided that the heating means of the acid reservoir, in conjunction with the control means, are designed to heat the oxalic acid to 157° C., 157° C. being the sublimation point of oxalic acid.

However, it is pointed out that the present invention is not limited to the use of acids in solid form. In principle, acids which are liquid at room temperature can also be used. An example of this is nitric acid. Nitric acid enables the binder to be removed from the green body relatively quickly.

The acid reservoir can be connected to the debinding chamber in a variety of ways. An embodiment of this provides that the debinding chamber and the acid reservoir are designed in one piece. Alternatively, the debinding chamber and the acid reservoir are connected via a closure, for example a quick-release closure are connected to each other, so that the acid reservoir can be removed and cleaned or refilled with acid in a simple manner.

In a further variant, the device comprises an exchangeable acid cartridge which contains the acid and which is inserted into the acid reservoir. This allows a particularly effective and safe handling of the acid. The acid cartridge contains granules of oxalic acid, for example. By heating the granules, the granules sublimate into the gaseous state.

Furthermore, it can be provided that a valve is arranged between the acid reservoir and the debinding chamber, which valve can open and close a flow-mechanical connection between the acid reservoir and the debinding chamber. The valve is designed, for example, as a slide valve that can be moved electrically, pneumatically and/or hydraulically. Configurations provide that the valve is temperature-resistant and acid-resistant at least up to a temperature of 200°C.

An embodiment of the invention provides that the debinding station includes external heating in order to provide a uniform temperature inside the debinding chamber. For example, electric heating mats are provided that encompass the entire debinding chamber, so that the temperature distribution in the debinding chamber is as homogeneous as possible. Alternatively or in addition, the heating can be provided by thermal oil or by heating elements located within a wall of the debinding chamber.

Furthermore, it can be provided that the debinding station has a fan arranged in the debinding chamber and air baffles for homogeneous material and temperature distribution. In order to operate the fan, it can be provided that a motor is arranged outside the debinding chamber, which motor drives the fan via a shaft projecting into the debinding chamber. A seal is provided at the entry of the shaft into the debinding chamber, which represents a gas-tight and acid-tight rotary feedthrough and prevents gas from escaping.

• - Aufnahme einer Säure, die zur Mitwirkung bei der Entbinderung eines Grünkörpers geeignet ist, in einem Säurereservoir, welches an eine beheizbare Entbinderstation zur Entbinderung des Grünkörpers angeschlossen ist,
• - Erhitzen der Säure im Säurereservoir durch von der Entbinderstation unabhängige Heizmittel, sodass die Säure zumindest teilweise in gasförmigen Zustand übergeht, dabei
• - Steuerung der Heizmittel zur Dosierung der Menge an Säure, die für die Entbinderung in gasförmigen Zustand übergeht,
• - Gasaustausch zwischen dem Säurereservoir und der Entbinderstation, bei dem die gasförmige Säure zumindest teilweise in die Entbinderstation strömt, und
• - Entbindern des Grünkörpers in der Entbinderstation unter Mitwirkung der gasförmigen Säure.

In a further aspect of the invention, the invention relates to a method for debinding a green body, which has the following steps:

• - Acquisition of an acid, which is suitable for participating in the debinding of a green body, in an acid reservoir, which is connected to a heatable debinding station for debinding of the green body,
• - Heating the acid in the acid reservoir by means of heating independent of the debinding station, so that the acid is at least partially converted into the gaseous state
• - control of the heating means for dosing the amount of acid that turns into gaseous state for debinding,
• - Gas exchange between the acid reservoir and the debinding station, in which the gaseous acid flows at least partially into the debinding station, and
• - Debinding of the green body in the debinding station with the participation of the gaseous acid.

One embodiment of the method provides that the acid is taken up in the acid reservoir in the solid state and sublimes when heated, the temperature of the heating means being controlled in such a way that the temperature of the acid reservoir is above or below the sublimation temperature of the acid.

• 1 ein erstes Ausführungsbeispiel einer Vorrichtung zur Entbinderung eines Grünkörpers mit einer Entbinderkammer und einem gesonderten Säurereservoir;
• 2 ein weiteres Ausführungsbeispiel einer Vorrichtung zur Entbinderung eines Grünkörpers mit einer Entbinderkammer und einem gesonderten Säurereservoir, wobei das Säurereservoir über mehrzonige Heizmittel beheizbar ist;
• 3 ein weiteres Ausführungsbeispiel einer Vorrichtung zur Entbinderung eines Grünkörpers mit einer Entbinderkammer und einem gesonderten Säurereservoir, wobei das Säurereservoir eine Patrone umfasst; und
• 4 ein weiteres Ausführungsbeispiel einer Vorrichtung zur Entbinderung eines Grünkörpers mit einer Entbinderkammer und einem gesonderten Säurereservoir, wobei zwischen der Entbinderstation und dem Säurereservoir ein Ventil angeordnet ist.

The invention is explained in more detail below with reference to the figures of the drawing using several exemplary embodiments. show:

• 1 a first embodiment of a device for debinding a green body with a debinding chamber and a separate acid reservoir;
• 2 a further exemplary embodiment of a device for debinding a green body with a debinding chamber and a separate acid reservoir, the acid reservoir being heatable via multi-zone heating means;
• 3 a further exemplary embodiment of a device for debinding a green body with a debinding chamber and a separate acid reservoir, the acid reservoir comprising a cartridge; and
• 4 a further exemplary embodiment of a device for debinding a green body with a debinding chamber and a separate acid reservoir, a valve being arranged between the debinding station and the acid reservoir.

The 1 until 4 each represent exemplary embodiments of a device for catalytic debinding of a green body. The green body can be a metallic and/or ceramic pressure part, which consists of a metal or ceramic powder mixed with a binder. The printed part is created, for example, with a manufacturing process known as “Fused Deposition Modeling” (FDM) or “Fused Filament Fabrication” (FFF). procedure. In this manufacturing process, a filament is manufactured in layers in a printer unit to form a metallic or ceramic printed part. The filament comprises a metal or a ceramic powder mixed with a binder, typically organic. Alternatively, the base body is produced, for example, by metal powder injection molding or ceramic powder injection molding.

The 1 shows a device for debinding a green body, in which a plurality of green bodies 1 are arranged on shelves 25 in a debinding station 2 . The binder is released from the base bodies 1 by means of a gaseous acid under the action of heat.

The debinding station 2 has a corrosion-resistant debinding chamber 20 made of stainless steel, for example, around which an external heater in the form of a large number of heating mats 9 is arranged for uniformly heating an interior 21 of the debinding chamber 20 . The heating mats 9 are connected to a controller 10, which controls the heat output of the heating mats 9 and thus the temperature in the interior 21 to a desired value.

In the interior 21 of the debinding chamber 20, a fan 6 and air baffles 7 are also arranged. They serve to evenly distribute gaseous acid and temperature. The fan 6 in the illustrated embodiment is driven by a motor 8 via a shaft 81 , the motor 8 being arranged outside the debinding chamber 20 . A seal 82 is provided at the entry of the shaft 81 into the debinding chamber 20 , which seals off the interior space 20 of the debinding chamber 20 and prevents gas from escaping from the debinding chamber 20 . The motor 8 can also be controlled via the controller 10.

For introducing a green part 1 into the interior 21, the debinding station 2 has a door 22 which is provided with an acid-resistant and acid-tight O-ring. Provision can also be made to introduce nitrogen and/or other gases into the interior 20 of the debinding station 2 that are necessary or beneficial during the debinding process.

The device also includes an acid reservoir 3 . This forms an additional chamber that is spatially separated from the debinding chamber 20 . The acid reservoir 3 is detachably arranged on the underside or base plate of the debinding chamber 20 via a quick-release fastener 12 . The acid reservoir 3 forms an interior space 31 which is fluidically connected to the interior space 21 of the debinding chamber 20, i. H. Gaseous acid provided in the acid reservoir can flow into the interior 21 of the debinding chamber 20 .

The acid reservoir 3 also includes heating means 5 for heating the acid reservoir 3 independently of the debinding chamber 20. These heating means 5 are also formed by heating mats, for example, although this is only to be understood as an example and basically any heating means can be used. The heating power of the heating means 5 is set by the controller 10 .

The acid reservoir 3 contains an acid 4 that is required for the debinding process. For this purpose, it is provided that the acid 4 is introduced into the acid reservoir 3 in a solid form, for example in the form of granules. The heating means 5 make it possible to heat the acid 4 to a desired temperature and thus to control the amount of acid 4 required for debinding, which flows into the debinding chamber 20 in gaseous form.

In one embodiment, oxalic acid is used as acid 4, which sublimes at a temperature of 157° C., ie undergoes a direct phase transition from the solid to the gaseous state. The control means 10 control the heating means 5 in such a way that the temperature of the acid reservoir 3 is above or below the sublimation temperature of 157° C., so that it is easy to set whether and how much gaseous acid flows into the debinding chamber and changes to the gaseous state and is available there for debinding.

In other embodiments, other acids that are in the solid state at room temperature may be used. In addition, it can alternatively be provided that the acid is present in the acid reservoir 3 in the liquid state and is converted from the liquid state into the gaseous state by heating. An example of a liquid acid is nitric acid.

The acid reservoir 3 and the debinding chamber 20 constitute separate chambers in that their internal temperature is independently adjustable. The temperature in the interior 21 of the debinding chamber 20 is set by the external heater 9 . The temperature in the interior 31 of the acid reservoir 3 is set by the heating means 5 . The acid reservoir 3 and the debinding chamber 20 are fluidly coupled to one another, so that gaseous acid can flow from the acid reservoir 3 into the debinding chamber 20 and the gas atmosphere can be adjusted there. However, this fluidic coupling causes no or only a slight thermal coupling, so that the temperature of the acid reservoir 3 does not is determined by the temperature of the external heater 9, but by the temperature of the heating means 5. Provision can optionally be made for the debinding chamber 20 and the acid reservoir 3 to be arranged at a significant spatial distance from one another in order to ensure thermal decoupling. In this respect, the figures are only to be understood schematically.

A gas exchange takes place through the connection between the interior 31 of the acid reservoir 3 and the interior 21 of the debinding station 2 , in which the gaseous acid flows from the acid reservoir 3 into the debinding station 2 after heating. It is possible to control the heat input of the heating means 5 onto the acid 4 via the controller 10 connected to the heating means 5 of the acid reservoir 3 . In this way it is possible to precisely control the amount of acid that is converted into the gaseous state and made available for debinding.

It is pointed out that the type of connection of the acid reservoir 3 to the debinding chamber 20 by means of a quick-release fastener 12 is only to be understood as an example. In principle, any connecting means can be used, for example a flange connection. Furthermore, alternatively, it can be provided that the acid reservoir is designed in one piece with the debinding chamber 20 , the acid being fed into the acid reservoir 3 via the door 22 .

The 2 shows a further embodiment of a device for debinding a green part 1, the basic structure of the device 1 is equivalent to. In contrast to the in 1 illustrated embodiment, the acid reservoir 3 has a multi-zone heating means 5 . The heating means 5 includes three heating areas 51 which form three separate heating zones of the acid reservoir 3 . The heating areas 51 or the heating zones 51 formed by them can be operated via the controller 10 in such a way that there are different temperatures in the individual heating zones and therefore a different heat input to the acid 4 . The heating areas 51 are arranged at different heights around the acid reservoir 3 in the vertical direction. In this way, improved control of the heat input into the acid 4 is possible. Consequently, how much acid is gasified and provided to the debinding unit 2 can be more precisely controlled.

The 3 FIG. 12 represents a further embodiment variant of a device for debinding a green part 1. The acid reservoir 3 accommodates a cartridge 35 which contains the acid 4. FIG. The cartridge 35 is suspended, for example, in a lower opening in the floor of the debinding chamber 20, this being understood to be purely exemplary. The debinding chamber 20 and the acid reservoir 3 are designed in one piece in this variant, although this is only optional. The acid 4 is arranged in the cartridge 35 as granules or in some other way as a solid. In another embodiment, the acid in the cartridge 35 is filled with a liquid acid 4 .

The acid arranged in the cartridge 35 is heated in the manner explained by the heating means 5 , the heating means 5 being controlled by the control means 10 . In particular, the heating means are controlled via the control means 10 in such a way that the granules are heated above a sublimation temperature during debinding. Also in this embodiment, different heating zones 51 according to the 2 be provided.

The 4 12 represents an embodiment in which a controllable valve 15 is arranged between the acid reservoir 3 and the debinding chamber 20, which valve can open and close the opening between the acid reservoir 3 and the debinding chamber 20. In this way, the entry of gaseous acid 4 from the acid reservoir 3 into the debinding station 2 can be stopped. Closing can be useful, for example, if the proportion of gaseous acid in the gas mixture in the interior 21 exceeds a predefined limit value or if the acid reservoir 3 must be closed for safety reasons, for example when introducing a green body 1 into the debinding station 3. The valve 15 be closed when no debinding takes place in the debinding chamber 20 or when the acid reservoir 3 is removed from the debinding chamber 20.

The valve 15 is designed, for example, as a slide valve, the position of which can be adjusted via an actuator (not shown). The actuator can also be connected to the controller 10 .

In all of the exemplary embodiments, the controller 10 may include at least one processor and an associated storage medium containing program code which, when executed by the at least one processor, performs the control. The controller 10 contains measured values with regard to the temperature in the interior 21 of the debinding chamber 20 and in the interior 31 of the acid reservoir 3 as input variables, which are provided by sensors (not shown). In this case, further sensors can be provided which provide the controller 10 with measured values, for example with regard to the pressures in the debinding chamber 20 and the acid reservoir 3 as well as with regard to the gas composition in the debinding chamber 20. The controller 10 may contain "if-then" rules such as: "If the level of acidic gas in the debinding chamber 20 is below percentage X, then give a command to the Heating means 5 for heating the control chamber 3 above the sublimation temperature”. An even simpler control command could be: "Command the heating means 5 to heat the control chamber above the sublimation temperature for a period of 5 minutes after a corresponding control signal is present". The control to be carried out in each specific case is measured by the usual considerations of the person skilled in the art.

In this case, the “control” can also include regulation, provided sufficient feedback is provided to the control unit 10 via sensors with regard to the values to be set.

It is also pointed out that the controller 10 shown in the figures is used not only to control the heating means 5 but also, for example, the motor 8 and the external heater 9 . However, this is only to be understood as an example and schematically. Alternatively, separate controls for the heating means 5 and for the other components 8, 9 can be provided.

Furthermore, the controller 10 can in principle also be provided in a different way than via a processor and program code, for example via an analog circuit.

A sintering furnace for sintering the brown part produced by the debinding follows the device described in a manner known per se. During sintering, any residual binder still contained in the brown part also decomposes.

It should be understood that the invention is not limited to the embodiments described above, and various modifications and improvements can be made without departing from the concepts described herein. It is further pointed out that any of the features described can be used separately or in combination with any other features, provided they are not mutually exclusive. The disclosure extends to and encompasses all combinations and sub-combinations of one or more features described herein. If ranges are defined, these include all values within these ranges as well as all sub-ranges that fall within a range.

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• EP 0413231 A1 [0004]
• EP 2686286 A1 [0004, 0018]
• CN 106270506 A1 [0004]
• WO 9425205 A1 [0005]

Claims (18)

Device for debinding a green body (1), which has: - a debinding station (2) which comprises a heatable debinding chamber (20), - an acid reservoir (3), which is fluidically connected to the debinding chamber (20) and is designed and provided to receive an acid (4) required for debinding and the acid required for a debinding process of the green body (1) in the debinding chamber (20). provide gaseous state, - heating means (5) for heating the acid reservoir (3) independently of the debinding chamber (20), and - Control means (10) which are provided and set up to control the quantity of acid (4) required for debinding, which the acid reservoir (3) provides to the debinding chamber (20), by adjusting the temperature of the heating means (5). . device after claim 1 , characterized in that the heating means (5) have separate heating areas (51) for different heating zones of the acid reservoir (3), wherein the acid reservoir (3) and the acid (4) contained in it can be heated to different degrees in the different heating zones. device after claim 2 , characterized in that the various heating areas (51) are arranged vertically one above the other. Device according to one of the preceding claims, characterized in that the acid (4) is present in the acid reservoir (3) as a solid which changes directly into the gaseous state from a sublimation point. device after claim 4 , characterized in that the acid (4) is present in granular form in the acid reservoir (3). claim after claim 4 or 5 , characterized in that the acid (4) is oxalic acid. Device according to one of the preceding claims, as far as dependent on claim 4 , characterized in that the heating means (5) are controlled by the control means (10) such that the temperature of the acid reservoir (3) is above or below the sublimation temperature. Claim according to one of Claims 1 until 3 , characterized in that the acid (4) is present in liquid form in the acid reservoir (3) at room temperature. claim after claim 8 , characterized in that the acid (4) is nitric acid. Device according to one of the preceding claims, characterized in that the debinding chamber (20) and the acid reservoir (3) are designed in one piece. Device according to one of Claims 1 until 9 , characterized in that the debinding chamber (20) and the acid reservoir (3) are connected to one another via a closure (12). Device according to one of the preceding claims, characterized in that the device comprises a replaceable acid cartridge (35) which contains the acid and which is inserted into the acid reservoir (3). Device according to one of the preceding claims, characterized in that between the acid reservoir (3) and the debinding chamber (20) there is a valve (15) which opens and closes a flow-mechanical connection between the acid reservoir (3) and the debinding chamber (20). can. device after Claim 13 , characterized in that the valve (15) is a slide valve. Device according to one of the preceding claims, characterized in that the debinding station (2) has external heating (9) for the debinding chamber (20). Device according to one of the preceding claims, characterized in that the debinding station (2) has a fan (6) arranged in the debinding chamber (20) and air baffle plates (7) for material and temperature distribution. Process for debinding a green body, which has the steps: - receiving an acid (4), which is suitable for participating in the debinding of a green body (1), in an acid reservoir (3) which is connected to a heatable debinding station (2) for debinding of the green body (1), - heating of the acid (4) in the acid reservoir (3) by heating means (5) independent of the debinding station (2), so that the acid (4) is at least partially converted into a gaseous state, in the process - controlling the Heating means (5) for dosing the amount of acid (4) that changes into the gaseous state for debinding, - gas exchange between the acid reservoir (3) and the debinding station (2), in which the gaseous acid (4) is at least partially debinding station (2) flows, and - debinding of the green body (1) in the debinding station (2) with the participation of the gaseous acid. procedure after Claim 17 , characterized in that the acid (4) is received in the solid state in the acid reservoir (3) and sublimes when heated, the temperature of the heating means (5) being controlled such that the temperature of the acid reservoir (3) is above or below the sublimation temperature the acid lies.

Images