DE102020118093A1 - Process for manufacturing a workpiece using additive manufacturing - Google Patents

Abstract

Method for producing a workpiece (1) by means of additive manufacturing, comprising at least the following steps:a) providing a powdered material (2);b) first irradiating particles (3) of the material (2) in an irradiation area (4) with a first irradiation intensity, so that particles (3) of the material (2) in an area (5) adjoining the irradiation area (4) are prefixed to the material (2) in the irradiation area (4); andc) second irradiation of the particles (3) of the material (2) in the irradiation region (4) with a second irradiation intensity, the second irradiation intensity being greater than the first irradiation intensity.

Description

The present invention relates to a method for producing a workpiece using additive manufacturing. The method can be used in particular to produce a housing for a sanitary fitting.

It is known from the prior art to manufacture workpieces, such as metal components, by means of additive manufacturing using what are known as 3D printing methods. In additive manufacturing, the workpieces are built up in layers, for example by partially irradiating a powdered material. The irradiation can take place in particular by means of a laser. Here, the powdery material in an irradiation area of a laser beam of the laser is suddenly heated, so that an atmosphere around a focal point of the laser beam is overheated and generates a pressure wave that explosively moves away or "blasts" particles of the powdery material in adjacent areas of the irradiation area. This effect can mean that particularly fine structures of the workpiece cannot be printed and/or that additional support structures have to be provided.

Proceeding from this, it is the object of the present invention to at least partially solve the problems described with reference to the prior art. In particular, a method for producing a workpiece by means of additive manufacturing is to be specified, by means of which finer structures of the workpiece can be produced and/or by means of which support structures can be avoided at least in part.

These objects are solved by the features of the independent patent claim. Further advantageous refinements of the method are specified in the dependent patent claims. It should be pointed out that the features listed individually in the dependent patent claims can be combined with one another in any technologically meaningful way and define further refinements of the invention. In addition, the features specified in the patent claims are specified and explained in more detail in the description, with further preferred configurations of the invention being presented.

1. a) Bereitstellen eines pulverförmigen Materials;
2. b) erstes Bestrahlen von Partikeln des Materials in einem Bestrahlungsbereich mit einer ersten Bestrahlungsintensität, sodass Partikel des Materials in einem an den Bestrahlungsbereich angrenzenden Bereich an dem Material in dem Bestrahlungsbereich vorfixiert werden; und
3. c) zweites Bestrahlen der Partikel des Materials in dem Bestrahlungsbereich mit einer zweiten Bestrahlungsintensität, wobei die zweite Bestrahlungsintensität größer ist als die erste Bestrahlungsintensität.

A method for manufacturing a workpiece by means of additive manufacturing, which comprises at least the following steps, contributes to this:

1. a) providing a powdered material;
2. b) first irradiating particles of the material in an irradiation area with a first irradiation intensity, so that particles of the material in an area adjoining the irradiation area are prefixed to the material in the irradiation area; and
3. c) second irradiation of the particles of the material in the irradiation area with a second irradiation intensity, the second irradiation intensity being greater than the first irradiation intensity.

The sequence of steps b) and c) occurs in particular in chronological succession.

The method can be used, for example, to produce a workpiece for a sanitary fitting.

In step a), a powdered material is provided. The powdered material can be, for example, powdered metal such as stainless steel, copper, copper alloy or brass. The powdered material includes a large number of particles. The provision of the powdery material takes place in particular on a base plate on which the workpiece is formed. In particular, it can be provided in the form of a powder bed.

In the additive manufacturing of the workpiece, the workpiece is built up in layers by partial irradiation or exposure of the material. The irradiation can be carried out, for example, by a laser beam or an electron beam. Furthermore, the irradiation leads to at least partial melting of the particles of the material at the irradiated point of the powdery material, so that individual particles of the powdery material bond to one another. Building up the workpiece in layers can be understood, for example, as meaning that a plurality of layers are formed one after the other or layer by layer. A layer essentially describes a horizontal cross-section through the component. In this context, it can also be provided that the layered construction is carried out in or with a powder bed of the powdered material. In additive manufacturing, for example, selective laser melting (SLM) or selective laser sintering (SLS) can be used. A 3D printer can be used for this purpose, for example.

mit:

P:

Strahlleistung oder Laserleistung in Watt

DS:

Dicke der Pulverschicht

ΔyS:

Versatz des Laserstrahls zwischen zwei Schmelzspuren

vS:

Geschwindigkeit des Laserstrahls oder Elektronenstrahls (Scangeschwindigkeit)

In step b), particles of the material are first irradiated or exposed to light in an irradiation area with a first irradiation intensity. The irradiation area is in particular a (limited) area on which a beam for heating the material in additive manufacturing strikes the material and/or on which the beam in additive manufacturing is directed and/or focused. the irradiation area can in particular have a round cross-section. The provision of the pulverulent material according to step a) can take place at the same time as step b) or with a time overlap. In step b), the material is first irradiated with a first irradiation intensity. The irradiation intensity can be adjusted in particular via the operating parameters of the 3D printer and/or a laser. The higher the irradiation intensity, the more the material is heated in the irradiation area and/or the more the individual particles of the powdery material are fused together. The irradiation intensity can be, for example, a volume energy (E _V ) that is introduced into the irradiation area. The volume _{energy (E V} ) is calculated using the following formula: $${\text{E}}_{\text{V}}=\frac{\text{P}}{{\text{D}}_{\text{S}}\ast \Delta {\text{y}}_{\text{S}}\ast {\text{v}}_{\text{S}}}\left[{\text{K/mm}}^3\right]\left(\text{joules per cubic millimeter}\right)$$

With:

P:

Beam power or laser power in watts

DS:

Thickness of the powder layer

ΔyS:

Offset of the laser beam between two melting tracks

vS:

Speed of the laser beam or electron beam (scanning speed)

The irradiation intensity can thus be controlled, for example, by controlling the beam power or laser power of the laser.

Due to the first irradiation of the particles of the material in the irradiation area, not only are the particles of the material in the irradiation area at least partially fused with one another, but also particles of the material in an adjacent area are prefixed. “Prefixed” can in particular be understood to mean that the particles in the adjoining area are not completely fused with one another, but are only partially melted and/or weakly connected to one another (materially bonded). The adjoining area can extend, in particular, in a ring shape around the irradiation area.

In step c), a second irradiation or exposure of the particles of the material in the irradiation area takes place with a second irradiation intensity. The layered construction of the workpiece in step c) can also be carried out in or with a powder bed of the powdered material. This can also mean that the powdered material is provided according to step a) at the same time as step c) or with a time overlap. In step c), as in step b), for example selective laser melting (SLM) or selective laser sintering (SLS) can be used. The 3D printer can also be used for this. As a result of the second irradiation, particles of the material in the irradiation area and/or in the adjoining area can be at least partially further fused together. Furthermore, in step c), a density of the material in the irradiation area and/or the adjoining area can be increased to a desired density.

In addition, in step c) a complete material connection can be created under the individual particles of the material. The pre-fixing of the particles of the material allows finer structures to be fabricated and at least partially reduces the need for support structures.

The second irradiance is greater than the first irradiance. For example, the second irradiance may be at least 10% greater than the first irradiance.

If steel is used as the material in powder form, a first radiation power of the laser can be 140 watts to 180 watts in order to generate the first radiation intensity.

When using steel as the powdered material, the second radiation power of the laser can be 220 watts to 300 watts in order to generate the second radiation intensity.

The first irradiation intensity can be so low that the first irradiation does not produce a pressure wave that moves particles of the material away from the irradiation area. In particular, the first irradiation intensity can be so low that the first irradiation does not produce a pressure wave that moves particles of the material away from the adjacent area.

The irradiation of the particles of material in the irradiation area can be interrupted between steps b) and c). This can mean in particular that the material in the irradiation area is not irradiated between steps b) and c). Furthermore, this can also mean that the laser does not emit a laser beam. Interruption can last for example 1 to 5 seconds.

The material can be cooled down by at least 10 °C (Celsius) between steps b) and c).

In step b), particles of the material can be pre-fixed at a distance of up to 5 mm (millimeters) from the irradiation area.

The info-fixed particles of the material produced in step b) can be used to produce an overhang of the workpiece. The overhang can in particular be a protruding area of the workpiece and/or an area protruding from the workpiece. The overhang can be produced in particular without a support structure.

The workpiece can be a housing for a sanitary fitting. Sanitary fittings serve in particular to provide a liquid as required at a washbasin, sink, shower and/or bathtub. The housing can also be designed in particular with an outlet and/or an outlet opening for the liquid. Furthermore, the housing for accommodating functional elements of the sanitary fitting, such as. B. shut-off valves, mixing valves and / or liquid lines or the like, be formed.

• 1: ein nach einem hier beschriebenen Verfahren hergestelltes Werkstück in einer Seitenansicht; und
• 2: eine Detailansicht des Werkstücks während seiner Herstellung in der Seitenansicht.

The present invention and its technical environment are explained in more detail below with reference to the figures. It should be pointed out that the invention should not be limited by the exemplary embodiment shown. In particular, it is also possible to extract partial aspects of the facts explained in the figures and to combine them with other components of the description. It shows as an example and schematically:

• 1 : a side view of a workpiece produced according to a method described here; and
• 2 : a detailed side view of the workpiece during its manufacture.

1 shows a workpiece 1 that was produced using a method described here. For this purpose, an initially powdery material 2 was provided on a base plate 9 . The workpiece 1 was then built up in layers with an overhang 7 by partial irradiation of the material 2 using a laser 8 .

the 2 shows the workpiece 1 during its manufacture in a 1 Area marked with a rectangle 10 in a detailed view. In the 2 a first irradiation or exposure of particles 3 of the powdered material 2 takes place by the laser 8 with a laser beam 11 in an irradiation area 4 with a first irradiation intensity. The laser beam 11 has a round cross section. Particles 3 of the material 2 are pre-fixed to the material 2 of the irradiation area 4 in an area 5 adjoining the irradiation area 4 . The first irradiation intensity during the first irradiation is so low that the laser beam 11 does not generate a pressure wave that explosively moves particles 3 in the adjoining area 5 away from the irradiation area 4 . As a result, particles 3 in the adjoining area 5 can be melted with the particles 3 in the irradiation area 4 and bonded to them. The adjoining area 5 is ring-shaped and extends around the irradiation area 4. The first irradiation of the particles 3 in the irradiation area 4 prefixes particles 3 up to a distance 6 from the irradiation area 4 in the adjoining area 5. The particles 3 of the material 2 in the irradiation area 4 are more strongly interconnected than the particles 3 of the material 2 in the adjacent area 5. Therefore, the material 2 in the irradiation area 4 has a higher density than in the adjacent area 5. After the first Irradiation can be interrupted, so that the material 2 cools down. As a result, thermal stresses in the material 2 can be reduced. A second irradiation of the particles 3 of the material 2 in the irradiation area 4 can then take place with a second irradiation intensity. The second irradiation intensity can be higher than the first irradiation intensity because the pressure wave generated by the laser beam 11 can no longer explosively move the pre-fixed particles 3 in the adjoining area 5 .

With the proposed method, finer structures can be produced and supporting structures can be avoided.

Reference List

1

workpiece

2

material

3

particles

4

irradiation area

5

adjacent area

6

distance

7

overhang

8th

laser

9

base plate

10

rectangle

11

laser beam

Claims (7)

Method for producing a workpiece (1) by means of additive manufacturing, comprising at least the following steps: a) providing a powdered material (2); b) first irradiation of particles (3) of the material (2) in an irradiation area (4) with a first irradiation intensity, so that particles (3) of the material (2) in an area (5) adjoining the irradiation area (4) on the Material (2) in the irradiation area (4) are pre-fixed; and c) second irradiation of the particles (3) of the material (2) in the irradiation area (4) with a second irradiation intensity, the second irradiation intensity being greater than the first irradiation intensity. Method according to one of the preceding claims, wherein the first irradiation intensity is so low that no pressure wave is generated during the first irradiation, which moves particles (3) of the material (2) away from the irradiation area (4). Method according to one of the preceding claims, wherein the irradiation of the particles (3) of the material (2) in the irradiation area (4) is interrupted between steps b) and c). Method according to one of the preceding claims, wherein the material (2) is cooled between steps b) and c). Method according to one of the preceding claims, wherein in step b) particles (3) of the material (2) are pre-fixed at a distance (6) of up to 5 mm from the irradiation area (4). Method according to one of the preceding claims, wherein the pre-fixed particles (3) of the material (2) produced in step b) are used to produce an overhang (7) of the workpiece (1). Method according to one of the preceding claims, in which the workpiece (1) is a housing for a sanitary fitting.

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