DE102017219977A1 - METHOD FOR GENERATING A COMPONENT - Google Patents

Abstract

The present invention relates to a method for the generative, layered construction of a component (60) made of a material in which in addition to an irradiation is heated inductively, wherein the induction coil (5) over an action surface (9) of time, which by vertical projection of a Impact region (2aa, 2ba, 2ca) results in the at least one layer (2a), a coil path (8) describes, and wherein the coil path (8) at least two sections (8a, b), which extend at an angle relative to each other.

Description

Technical area

The present invention relates to a method for the generative, layered construction of a component made of a material.

State of the art

Generative manufacturing methods not only allow a rapid construction of prototypes, but it can, for example, due to their geometry otherwise difficult to manufacture components or components are manufactured with specific material properties. The structure is done, for example. Layer by layer, and it can also generate geometries that z. B. would not be accessible by a casting process. In the layered structure, for example, sequentially applied layer by layer of a powdery component material. After applying a layer, it is selectively irradiated, for. B. with a laser, and so solidified in a desired range (eg., By melting or sintering). Subsequently, the next powder layer is applied and solidified according to the component geometry to be produced in certain areas.

Presentation of the invention

The present invention is based on the technical problem of specifying a particularly advantageous method for the generative, layered construction of a component.

According to the invention this object is achieved with the features of claim 1. Thus, in order to assist solidification with an induction coil, the component produced so far is heated inductively in an area of action, which may, for example, help prevent cracking in the component due to temperature gradients. In the present case, the induction coil is additionally moved. In this movement, it describes a coil path over an area of action associated with the area of action, and this should have at least two sections extending at an angle relative to each other. The coil path may, for example, be curved, or may also be constructed from a plurality of sections which are each straight, set at an angle to one another, cf. below in detail. In simple terms, the induction coil is not simply moved in a straight line over the contact surface, which advantageously allows optimization of the heating strategy or adaptation to the component geometry. The coil path can thus, for example, also be matched with an irradiation or exposure pattern with which the area to be solidified per layer is filled.

Preferred embodiments are to be found in the dependent claims and the entire disclosure, wherein the presentation does not always distinguish in detail between process or device aspects; In any case, implicitly, the disclosure should be read with regard to all categories of claims, in particular always to the method as well as to a device that is set up for a corresponding method.

The coil path lies in the contact surface, this results from vertical projection of the exposure region in the at least one layer, ie the layer which is produced at this time (and inductively heated in the production thereof). The contact surface is usually a (smaller) portion of the currently processed layer; In an arrangement of the induction coil over the contact surface is given an inductive coupling with the previously produced part of the component. Decisive for the coupling is not only the area fraction solidified in the currently processed layer. That region of the component produced to date, into which the induction coil arranged on the surface of the layer currently being processed can in principle couple, is referred to as the "exposure region".

In the Einwirkbereich the magnetic field of the induction coil can still penetrate in such a way that an inductive heating is possible. An influencing variable is therefore first the penetration depth of the magnetic field. Furthermore, the area of action in the at least one layer is also determined by where in the layer (s) has previously been solidified (see also below). In solidified areas eddy currents can form and inductive heating is possible. The effective area is then obtained by vertical projection of the area of action into the currently processed layer, cf. also 2 for illustration. In the case of the vertical projection into the at least one layer, it is considered in simplified terms as a surface (specifically, this surface should lie on the surface of the at least one layer).

The coil path is considered to be the line which describes the induction coil over the contact surface. As a rule, the induction coil can describe an overall greater moving distance over the entire layer currently being processed, but the "coil path" is then only that part of it which lies in the contact surface. Reversal points or the like, which has the coil movement outside of the contact surface, so remain in the main claim according angled course out of consideration. The coil path may in particular result in a path which describes a maximum of the magnetic field strength generated by the induction coil in the contact surface when the induction coil is moved over the contact surface. The coil path may, for example, also result as an intersection and as a result of the movement then as a cutting line having the surface of action with the (moving) axis of the induction coil (the axis along which the induction coil has its main magnetic direction). If the induction coil is switched off in the meantime, no magnetic field is generated and the coil path is interrupted so far.

As "induction coil" is understood in general any conductor geometry that allows an inductive heating. In a simple case, it could also be merely a conductor loop, but it is also an arrangement with a plurality (at least two) turns possible, which may be arranged in the form of a cylindrical or preferably flat coil. Possible upper limits of the number of turns may be, for example, not more than 50, 40, 30, 20, 10 or 5 (increasingly preferred in the order of entry). Preferably, an alternating field is applied, the induction coil can, for example, with a capacitor form a resonant circuit. The penetration depth of the magnetic field can then depend, for example, on the frequency of the alternating field.

Typical penetration depths of the magnetic field are in the millimeter range, so for example. Lower limits at least 0.5 mm or 0.8 mm and (independent) upper limits at most 10 mm, 8 mm, 6 mm, 4 mm, 2 mm, 1.5 mm (increasingly preferred in the order of entry). The usual layer thicknesses are smaller, upper limits can be, for example, at most 200 .mu.m, 150 .mu.m, 100 .mu.m, 80 .mu.m, 60 .mu.m or 50 .mu.m, with possible (independent) lower limits at least 5 .mu.m, 10 .mu.m or 15 .mu.m (increasingly preferred in the order of entry). This illustrates that the "exposure area" in the construction direction (this corresponds to the thickness direction of the layers) extends over at least 2, 4, 6, 8 or 10 layers (number of layers n), which is applied directly in front of the at least one layer and selectively solidified (possible upper limits may, for example, be at most 500, 400, 300, 200, 100 shifts).

In the processing of the n + 1-th layer, for example, the "contact surface" can result from a consideration of the layers n produced immediately above, with the region of each of these layers being solidified to produce this specific component perpendicular to the at least one layer n + 1 is projected (several components can be produced in parallel, but the solidified area is not considered). With regard to a quantification of the layer number n, reference is made to the above information. Each of these projections then yields a partial area, and the contact area results as a union of these partial areas and of the area solidified in the n + 1-th layer.

At least two sections of the coil path should extend "angled" relative to one another, ie not parallel to one another; The sections may be perpendicular or oblique (not parallel and not perpendicular) to each other. Preferably, more than two sections of the coil path are angled relative to each other (in pairs). Generally, in the context of this disclosure, "a" and "an" are to be read as indefinite articles and thus without expressly indicating otherwise always as "at least one" and "at least one".

In a preferred embodiment, the at least two sections at an angle of at least 45 °, further and more preferably at least 60 ° or 75 °. Advantageous upper limits are in the order of naming increasingly preferred at most 135 °, 120 °, or 105 °, upper and lower limits are generally also disclosed independently. In general, the sections do not necessarily have to extend in a straight line, with tangents being then applied to the sections for the angle consideration. Nevertheless, a coil path that extends in sections in a straight line may nevertheless be preferred. An incoming direction of a respective section also in the case of angle observation results from the direction of movement of the induction coil.

In a preferred embodiment, the coil path or at least a portion thereof extends spirally around a point in the at least one layer. The coil path can therefore extend over the circulation to the point or away from it (the direction of extension of the coil path is determined by the direction of movement of the induction coil). In this case, in particular, a stepped extension possible, a corresponding coil path can therefore also be composed of a plurality of each straight section. The spiral shape can allow a particularly good "filling" of the contact surface and thus a good support for solidification. In particular, the coil path can also represent a Fermatian spiral, that is to say initially to the center and then away from it (or vice versa). In other words, the direction of rotation may change.

In a preferred embodiment, the coil path extends at least partially curved. He then has at least partially a curve shape. This can be provided in combination with straight sections in each case, so that, for example, the or the curve sections (e) in each case connects or connect two straight sections for themselves. The coil path can also have a total waveform.

In a preferred embodiment, the coil path at least over the greater part of its extension describes a continuous, uninterrupted path. In any case, the "greater part" means more than 50% of the total extent, with at least 60%, 70%, 80% and 90%, respectively, being increasingly preferred in the order in which they are mentioned; the coil path can also be uninterrupted (100%). In general, however, such an uninterrupted extension is not mandatory, but the coil path can, for example, be constructed of several parts which each extend from edge to edge of the contact surface (a direction reversal then takes place outside of the contact surface).

In a preferred embodiment, a part of the coil path extends along an edge of the contact surface, so initially an edge region is traversed. In this case, the coil path can preferably follow the contour of the edge, at least in a certain approximation (not necessarily exactly, but in the manner of an averaging).

In a preferred embodiment, the edge is an outer edge of the contact surface, which lies on the outside with respect to directions from the centroid of the contact surface. Preferably, this outer edge is then initially traveled, that is, the part of the coil path extending along the outer edge is thus at the beginning thereof.

The contact surface can also have an inner edge, namely, if the component encloses a (partial) cavity. In general, with the induction coil, initially such an inner edge can be traversed, but in a preferred embodiment, first the outer edge and then the inner edge is traversed, that is, a first part of the coil path extends along the outer edge and a subsequent part along the inner edge. These parts of the coil path need not necessarily follow one another directly, in between the coil path can, for example, also describe a spiral or meander shape for filling in the surface.

In a preferred embodiment, the coil path in the at least one layer and another coil path in a directly following layer are at least partially overlapping-free, that is, in any case, not completely congruent. In other words, the coil path is thus changed from the at least one to the immediately following layer. Preferably, there may be several such changes in the coil path, although not necessarily between all layers. The coil path can thus remain the same over several layers and then be changed, in order then to remain the same over several layers.

The overlap or the absence thereof refers to the construction direction in which layer by layer is set to each other. A certain offset between the coil paths can be achieved, for example, already with mutually offset starting points. But there may also be further deviations, the coil paths can then, for example. (Partially) rotated to each other and / or scaled differently ("stretched" or "compressed"). Furthermore, the coil paths can also be completely independent of one another, for example meandering in one layer and spiraling in the other.

In the following, the ratio of irradiation or exposure relative to the coil path is considered. In general, for example, an electron beam source can also be provided as the radiation source. A laser source, for example a CO ₂ laser, Nd: Yag laser or Yb fiber laser, or else a semiconductor laser (diode laser) is preferred. The beam is then moved across the powder bed (this is "scanned"), by selective on or off of the beam, a respective area can be irradiated and solidified or not. In the following, the "irradiation area" is considered to be that area which would be irradiated by the source at a given point in time with irradiation released (although not permanently must be irradiated); the irradiation area is then moved across the layer and the radiation is selectively released. In its movement across the layer, the irradiation area describes a "scan path".

In a preferred embodiment, the scan path intersects the centerline of the coil path repeatedly, at least over part of the coil path. The scan path can therefore be oscillated back and forth in an oscillating manner about the center line of the coil path, ie a good part of its extent perpendicular to the center line of the coil path and thus to the feed direction of the coil. This can result in a particularly efficient combination of the (inductive) heating strategy with the irradiation or exposure pattern.

In a preferred embodiment, the scan path intersects the center line of the coil path, at least in sections, obliquely, ie not perpendicular. On the one hand, this can enable efficient filling of the surface to be heated / irradiated. With such an inclination, however, it is also possible, for example, to implement a variation of the scan path from layer to layer comparatively easily. The scan path can therefore be inclined for example in the at least one layer in one direction and be inclined in the following layer in an exactly opposite direction (so that therefore the scan paths are not congruent). This can offer advantages in terms of the material composite produced, figuratively favoring a good "gearing" of the layers.

In a preferred embodiment, the scan path intersects the center line at an angle of at least 20 °, further and particularly preferably at least 30 ° or 35 °. Advantageous upper limits can be in the order of naming increasingly preferred at most 80 °, 70 ° or 65 °, with the upper and lower limits are generally also disclosed independently. The angle of intersection is considered to be in each case the smaller of two angles, which include the center line of the coil path and the scan path at the intersection point (and which add up to 180 °).

In a preferred embodiment, the scan path extends at least in sections parallel to the center line. This can be particularly preferred in areas in which the coil path has a change in direction, in particular in "corners" or strongly contoured areas of the component. In such areas, the scan path may then preferably extend over at least 60%, 70%, or 80% of its extent parallel to the center line of the coil path (possible upper limits may be due to reverse loops etc., for example, at most 95%, 90% or more). 85% lie). With the scan line parallel to the center line, for example, said corner regions can be scanned efficiently, without surface areas having to be overrun unnecessarily many times.

In a preferred embodiment, the generatively produced component is a component of a turbomachine, for example a blade of the turbomachine, in particular an airfoil. Within the turbomachine but also other applications are conceivable, for example. The production of sealants, etc.

The invention also relates to a device for generatively constructing a component, this device having a radiation source, an induction coil and a movement unit for moving the induction coil. With the moving unit, the induction coil is movable over the layer or a powder bed holder. Furthermore, the device has a control unit for controlling the movement unit, wherein this control unit is set up to carry out a method described here. A control unit of the radiation source or of a radiation-guiding device (for example of a scanning mirror) is also preferably set up to carry out a method described here.

With regard to both the device and the method, reference is expressly made to the prior art appraisal which is to be considered part of the disclosure. the metallic material is preferably held in powder form, also referred to as "powder bed process".

list of figures

In the following, the invention will be explained in more detail with reference to embodiments, wherein the individual features in the context of the independent claims in another combination may be essential to the invention and continue to distinguish not in detail between the different categories of claims.

• 1a in schematischer Darstellung eine Vorrichtung zum generativen Aufbauen eines Bauteils aus einem Pulverbett, mit einer Induktionsspule zum unterstützenden induktiven Heizen;
• 1b als Detailansicht einen Schnitt zu 1a;
• 2 eine erste Möglichkeit, wie sich ein von der bewegten Induktionsspule beschriebener Spulenpfad über eine Einwirkfläche erstrecken kann;
• 3 eine zweite Möglichkeit, wie sich ein von der bewegten Induktionsspule beschriebener Spulenpfad über eine Einwirkfläche erstrecken kann;
• 4 eine dritte Möglichkeit, wie sich ein von der bewegten Induktionsspule beschriebener Spulenpfad über eine Einwirkfläche erstrecken kann;
• 5 eine erste Möglichkeit zur Abstimmung des Spulenpfads und eines Scanpfads der Bestrahlung;
• 6 eine zweite Möglichkeit zur Abstimmung des Spulenpfads und eines Scanpfads der Bestrahlung;
• 7 einen Schnitt durch ein generativ hergestelltes Schaufelblatt.

In detail shows

• 1a a schematic representation of an apparatus for generative construction of a component of a powder bed, with an induction coil for supporting inductive heating;
• 1b as detail view a cut too 1a ;
• 2 a first possibility of how a coil path described by the moving induction coil can extend over an action surface;
• 3 a second possibility of how a coil path described by the moving induction coil can extend over an action surface;
• 4 a third possibility of how a coil path described by the moving induction coil can extend over an action surface;
• 5 a first possibility for tuning the coil path and a scan path of the irradiation;
• 6 a second possibility for tuning the coil path and a scan path of the irradiation;
• 7 a section through a generatively produced airfoil.

Preferred embodiment of the invention

1a shows a device 1 for the generative construction of a component in a schematic representation. Shown is a view of the currently processed layer 2a , the previously processed layers 2 B . 2c lie underneath in the drawing plane, the construction direction points out of the plane of the drawing (and lies perpendicular to it). From the powdery, as a layer 2a applied material is solidified depending on the component geometry only selectively a range. This is done by irradiation with a laser beam 3 , the associated radiation source 10 is for the sake of clarity, in addition to the powder bed recording located, but in practice, for example. Be arranged above it. The laser beam 3 and thus an irradiation area 4 be over the layer 2a moved, which is selectively irradiated for selective solidification.

To assist solidification is also an induction coil 5 provided at a moving unit 6 is movably mounted. To the induction coil 5 An AC voltage is applied, including a power supply 7 is provided with a capacitor (the electrical leads and other details are not shown for clarity). With the induction coil 5 If necessary, the component or a part of it produced so far can be heated, which, for example, can help to prevent temperature gradients and thus crack formation during solidification.

The induction coil 5 describes in her movement about the layer 2 away a coil path 8th , in 1a however, for the sake of clarity, the induction coil is next to the coil path 8th shown. The coil path 8th runs according to the invention angled and in particular curved. So can the coil path 8th advantageously to the component contour or to the contour of an action surface 9 be adjusted.

1b illustrated in a parallel to the direction of construction section, as the contact surface 9 results. From the shift 2a which is being processed at this time becomes an area 2aa solidified, the rest of the area 2ab Not. Also in the previously processed layers 2 B . 2c each became an area 2ba . 2ca solidified, a respective different area 2 bb . 2cb not, according to the previously manufactured component. The inductive coupling is now determined on the one hand after a penetration depth 10 the magnetic field, on the other hand after the areas solidified in the previous layers 2ba . 2ca , The result is the effective area 9 through a vertical projection, these solidified areas 2aa . 2ba . 2ca into the currently processed layer.

2 shows a first way, as the coil path 8th the contact surface 9 can fill. The coil path 8th has several sections 8a . b on, which extend angled to each other. Shown is a spiral shape with the beginning on the outside and the coil path 8th extends to the middle. The coil path 8th is composed of six parts, intermittently. For each part, the circled digit indicates the starting point and the machining rank (the coil path 8th is driven from the inside to the outside). A similar coil path 8th but could also be constructed coherently without interruptions.

3 shows an already somewhat more complex impact surface 9 that is not just an outer edge 30 but also an inner edge 31 Has. The coil path 8th initially extends along the outer edge 30 , then the inner edge 31 left. In this case, there are interruptions between different parts of the coil path 8th so this is not connected.

4 illustrates a possibility, as with the same impact surface 9 a coil path 8th connected in such a way that also initially the outer edge 30 and then the inner edge 31 is traversed. In the present case has the coil path 8th the shape of a Fermatian spiral.

5 Illustrates how a scan path 50 the irradiation area 4 over the layer 2 describes (see also 1a) , relative to the coil path 8th , specifically its centerline, can extend. The scan path 50 In this case, the center line intersects obliquely (not at right angles), which is particularly easy a variation of the scan path 50 from layer to layer. Regardless of this, a variation of the coil path can also be used 8th from layer to layer, cf. also the description introduction in detail.

6 shows a scan path 50 which can be particularly advantageous place in areas where the coil path 8th describes a curvature or a corner. The scan vectors can also be considered as shell vectors here.

7 shows as generatively produced component 60 an airfoil. This has cavities in its interior 61 on, for example, to guide a cooling fluid. The coil path 8th can now extend initially curved along the side walls of the airfoil; then the webs 62 be driven in between.

LIST OF REFERENCE NUMBERS

Device for generative construction 1 layer 2 Layer, edited at the time 2a Area, solidified 2aa Area, not solidified 2ab previously processed layers 2b, 2c Areas, solidified 2ba, 2ca Areas not solidified 2bb, 2cb laser beam 3 irradiation area 4 induction coil 5 Bewegeeinheit 6 power Supply 7 coils path 8th Sections of it 8a, b impact surface 9 radiation source 10 outer edge 30 inner edge 31 scan path 50 component 60 cavities 61 Stege 62

Claims (14)

Method for the generative, layered construction of a component (60) made of a material, wherein the material is held in an informal or shape-neutral manner and selectively solidified by irradiation within the layered structure within each layer (2), and wherein at least one layer (2a) for assisting solidification with an induction coil (5) is the component produced until then in an area of action (2aa, 2ba, 2ca) is inductively heated, and wherein the induction coil (5) is moved during the inductive heating and thereby over an action surface (9) away, which by vertical projection of the Einwirkbereichs (2aa, 2ba, 2ca ) into which at least one layer (2a) results, describes a coil path (8), and wherein the coil path (8) has at least two sections (8a, b) which extend at an angle relative to one another. Method according to Claim 1 in which the at least two sections (8a, b) enclose an angle of at least 45 ° and at most 135 °. Method according to Claim 1 or 2 in which the coil path (8), which the induction coil (5) describes over the contact surface (9), extends at least in sections around a point in the at least one layer and at the same time in the manner of a spiral also at least in steps to the point towards or away from it. Method according to one of the preceding claims, in which the coil path (8) which the induction coil (5) describes across the contact surface (9) extends at least in sections in a curved manner. Method according to one of the preceding claims, in which the coil path (8), which the induction coil (5) describes across the contact surface (9), is coherent, ie uninterrupted, over at least the greater part of its extent. Method according to one of the preceding claims, in which the contact surface (9) has an edge (30, 31), the induction coil (5) being initially moved along the edge (30, 31), that is to say a part of the coil path (8). along the edge (30,31) extends. Method according to Claim 6 in which the edge (30, 31) is an outer edge (30) with respect to a centroid of the contact surface (9), the contact surface (9) also having an inner edge (31) and the induction coil (5) after moving along the Outside edge (30) along the inner edge (31) is moved, that is, a part of the coil path (8) following the first part along the inner edge (29) extends. Method according to one of the preceding claims, in which the coil path (8) in the at least one layer (2a) and a further coil path in a directly following layer are at least partially overlapping-free. A method according to any one of the preceding claims, wherein a scan path (50) on which an irradiation region (4) is moved over the at least one layer (2a) during the selective solidification irradiation is moved along the coil path (8) and while the center line intersects at least over a part of the coil path (8) repeatedly. Method according to Claim 9 in which the scan path (50) obliquely intersects the center line of the coil path (8) at least over the part of the coil path (8). Method according to Claim 10 in which the scan path (50) intersects the center line of the coil path (8) at least over the part of the coil path (8) at an angle of at least 20 ° and at most 80 °. Method according to one of the preceding claims, in which a scan path (50), on which an irradiation area (4) is moved during the irradiation for selective solidification over the at least one layer (2a), is moved along the coil path (8) and thereby at least over a part of the coil path (8) across the center line of the coil path (8). Method according to one of the preceding claims, in which the component (60) is a component of a turbomachine, in particular an airfoil or a seal carrier. Device (1) for the generative, layered build-up of a component (60) from a formless or shape-neutral held material, which device (1) comprises: - a radiation source (10) for irradiating and thus solidifying the material, - an induction coil (5) for inductive heating and - a movement unit (6) for moving the induction coil (5), the apparatus (1) for carrying out a method according to one of the Claims 1 to 13 set up.

Images