Method and apparatus for generating a work piece containing an information code

Abstract

A method and an apparatus (10) for generating a three-dimensional work piece containing an information code are provided. The method comprises the steps of applying a raw material powder (18) onto a carrier (14) by means of a powder application device (16), irradiating electromagnetic or particle radiation (22) onto the raw material powder (18) applied onto the carrier (14) by means of an irradiation device (20), and controlling the operation of the powder application device (16) and the irradiation device (20) so as to generate an information code pattern (36) on or in the work piece (12), wherein the information code pattern (36) is defined by the microstructure (34) of the work piece (12).

Claims

1. A method for generating a three-dimensional work piece, the method comprising the steps: applying a raw material powder onto a carrier by means of a powder application device, irradiating electromagnetic or particle radiation onto the raw material powder applied onto the carrier by means of an irradiation device, controlling the operation of the powder application device and the irradiation device so as to generate an information code pattern on or in the work piece, wherein the information code pattern is defined by the microstructure of the work piece; controlling the operation of the powder application device and the irradiation device so as to tailor the microstructure of the work piece such that a specific physically determinable microstructure parameter defining the microstructure is set in a first state or value and a second state or value based on the information code being represented by a first information code state or value and a second information code state or value, and wherein the first state/value of the specific physically determinable microstructure parameter corresponds to the first information code state/value and the second state/value of the specific physically determinable microstructure parameter corresponds to the second information code state/value.

2. The method of claim 1, further comprising the step: controlling the operation of the powder application device and the irradiation device so as to tailor the microstructure of the work piece such that the first state/value of the specific physically determinable microstructure parameter on the one hand and the second state/value of the specific physically determinable microstructure parameter on the other hand are defined by a first material composition or a first material distribution within the microstructure on the one hand and a second material composition or a second material distribution within the microstructure on the other hand, a relatively coarse grain size on the one hand and a relatively fine grain size on the other hand, a substantially directionally/dendritically solidified texture on the one hand and a substantially polycrystalline and/or substantially globulitic texture on the other hand, an anisotropic texture on the one hand and an isotropic texture on the other hand, and/or a first spatial direction of an anisotropic texture with respect to a build direction on the one hand and a second spatial direction of the anisotropic texture with respect to the build direction on the other hand, or vice versa.

3. The method of claim 1, further comprising the step: controlling the operation of the powder application device and the irradiation device so as to tailor the microstructure of the work piece such that the first state/value of the specific physically determinable microstructure parameter on the one hand and the second state/value of the specific physically determinable microstructure parameter on the other hand are defined by a first value of a mechanical property on the one hand and a second value of the mechanical property on the other hand, a first value of an electrical property on the one hand and a second value of the electrical property on the other hand, a first value of a thermal property on the one hand and a second value of the thermal property on the other hand, a first value of a magnetic property on the one hand and a second value of the magnetic property on the other hand, and/or a first value of a chemical property on the one hand and a second value of the chemical property on the other hand, or vice versa.

4. The method of claim 1, further comprising the step: controlling the operation of the powder application device and the irradiation device so as to tailor the microstructure of the work piece such that the first state/value of the physically determinable microstructure parameter is located on or restricted to a first spatial portion of the work piece and the second state/value of the physically determinable microstructure parameter is located on or restricted to a second spatial portion of the work piece, wherein the first and second portions are spatially disjoint.

5. The method of claim 1, further comprising the step: controlling the operation of the powder application device and the irradiation device so as to tailor the microstructure of the work piece such that the information code pattern forms a two-dimensional matrix code.

6. The method of claim 5, wherein the two-dimensional matrix code is a Quick Response Code.

7. The method of claim 1, wherein the information code pattern is generated using an encoding scheme.

8. The method of claim 1, wherein the information code pattern is a biunique mapping of the information code onto the microstructure of the work piece.

9. The method of claim 1, wherein the information code pattern represents a production date, a production location, a production method, a production apparatus, a producer, a company, a production series, a serial number, an identification of the work piece, or a destination.

10. A method for generating a three-dimensional work piece, the method comprising the steps: applying a raw material powder onto a carrier by means of a powder application device, irradiating electromagnetic or particle radiation onto the raw material powder applied onto the carrier by means of an irradiation device, controlling the operation of the powder application device and the irradiation device so as to generate an information code pattern on or in the work piece, wherein the information code pattern is defined by the microstructure of the work piece, and controlling the operation of the powder application device and the irradiation device so as to tailor the microstructure of the work piece such that the information code pattern forms a linear barcode.

11. A method for generating a three-dimensional work piece, the method comprising the steps: applying a raw material powder onto a carrier by means of a powder application device, irradiating electromagnetic or particle radiation onto the raw material powder applied onto the carrier by means of an irradiation device, controlling the operation of the powder application device and the irradiation device so as to generate an information code pattern on or in the work piece, wherein the information code pattern is defined by the microstructure of the work piece, and controlling the operation of the powder application device and the irradiation device so as to tailor the microstructure of the work piece such that the microstructure of the work piece is defined by at least one of a size of grains, a grain morphology and a texture, wherein, in particular, the grain morphology and/or the texture of the microstructure is defined by at least one of a substantially directionally/dendritically solidified grain morphology, a substantially polycrystalline grain morphology, a substantially globulitic grain morphology, an anisotropic texture, an isotropic texture and a spatial direction of an anisotropic texture with respect to a build direction.

Description

(1) Further features, advantages and technical effects of the invention will become apparent from the following description of exemplary embodiments with reference to the accompanying drawings, in which:

(2) FIG. 1 schematically illustrates an apparatus for generating a three-dimensional work piece containing an information code pattern,

(3) FIG. 2 schematically illustrates an information code pattern on or in a work piece generated by the apparatus of FIG. 1, and

(4) FIG. 3 illustrates a hardness map obtained from an information code pattern.

(5) FIG. 1 shows an apparatus 10 for generating a three-dimensional work piece 12. The apparatus 10 comprises a carrier 14 and a powder application device 16 for applying a raw material powder 18 onto the carrier 14. The raw material powder 18 has a nominal chemical composition (in weight %) of 0.02% C, 17% Cr, 10.5% Ni, and 2.3% Mo, the balance being Fe. The raw material powder 18 is provided in form of a spherical powder with a mean particle size of 40 m. The apparatus 10 further comprises an irradiation device 20 for emitting electromagnetic or particle radiation 22. In particular, the electromagnetic or particle radiation 22 is emitted by at least one radiation source 24 of the irradiation device 20 and is guided and/or processed by at least one optical unit 26 of the irradiation device 20. The carrier 14 is designed to be displaceable in vertical direction so that, with increasing construction height of a work piece, as it is built up in layers from the raw material powder on the carrier 14, the carrier 14 can be moved downwards in the vertical direction. The operation of the carrier 14, the powder application device 16 and the irradiation device 20 is controlled by means of a control unit 28. The apparatus 10 further comprises an input device 30 for inputting arbitrary information 32.

(6) The control unit 28 converts information 32 input by the input device 30 into an information code by employing a known encoding scheme, such as a linear barcode or a two-dimensional matrix code (e.g. QR-code), or the like. Alternatively, the control unit 28 converts automatically generated information into the information code. The information and thus the information code may represent a production date, a production location, a production method, a production apparatus, a producer, a company, a production series, a serial number, an identification of the work piece, a destination, or the like.

(7) For example, the input information 32 is indicative of a specific production apparatus and the information code is a linear barcode. In this case, the control unit 28 converts the data indicative of the specific production apparatus into a linear barcode encoding for example a name and/or a serial number of the specific production apparatus. The information code (i.e. the linear barcode) is represented by a first information code state, namely black bars or just state black, and a second information code state, namely white bars or just state white.

(8) In a further step, the work piece 12 containing the information code is generated. To this end, the control unit 28 controls the carrier 14, the powder application device 16 and the irradiation device 20 in dependence on the crystallization behavior of the raw material powder 18, in order to tailor the microstructure 34 of the work piece 12 generated from the raw material poser 18 by an additive construction method such that specific physically determinable microstructure parameter defining the microstructure 34 of the generated work piece is set in a first state 34a and a second state 34b based on the information code, wherein the first state 34a of the specific physically determinable microstructure parameter corresponds to the first information code state (black) and the second state 34b of the specific physically determinable microstructure parameter corresponds to the second information code state (white) (see FIG. 2).

(9) The first state 34a and the second state 34b differ from each other and are thus distinguishable. In the present example, the specific physically determinable microstructure parameter defining the microstructure 34 is the grain size of the microstructure 34 and the texture of the microstructure 34. The control unit 28 controls the carrier 14, the powder application device 16 and/or the irradiation device 20 in dependence on the crystallization behavior of the raw material powder 18, in order to tailor the microstructure 34 of the work piece 12 made of the raw material powder 18 by an additive construction method such that the first state 34a of the specific physically determinable microstructure parameter is restricted to a first spatial portion 35a of the work piece 12 (namely the portions indicated by the black bars of the work piece 12, see FIG. 2) and is defined by a relatively coarse grain size and by an anisotropic and substantially single crystalline and directionally solidified texture. Contrary thereto, the second state 34b of the specific physically determinable microstructure parameter is restricted to a second spatial portion 35b of the work piece 12 (namely the portions indicated by the white bars between the black bars of the work piece 12, see FIG. 2) and is defined by a relatively fine grain size and by an isotropic and substantially polycrystalline and globulitic texture (see FIG. 2).

(10) As a result the first and second states 34a, 34b of the specific physically determinable microstructure parameter define an information code pattern 36 by mapping the first and second information code states (black and white of the linear barcode) onto the information code pattern 36 on or in the work piece 12. Thus, the information code pattern 36 represents a biunique mapping of the information code onto the microstructure 34 of the work piece 12, wherefore the information code pattern 36 also forms the desired linear barcode (see FIG. 2). Hence, the generated work piece 12 is provided with the desired information (the word pattern) encoded in the information code pattern 36.

(11) Further, since the information code pattern 36 is encoded by a physically determinable microstructure parameter, namely the grain size and the texture of the microstructure 34, the information code pattern 36 and thus the provided information can be read out from the work piece 12, namely by determining the first and second states 34a, 34b of the physically determinable microstructure parameter by use of a position resolved optical and thus non-destructive measurement technique (e.g., microscope).

(12) Additionally, the different first and second states 34a, 34b of the specific physically determinable microstructure parameter result in different and distinguishable values of mechanical properties (e.g., strength, toughness, ductility, hardness or wear resistance), of thermal properties (e.g., thermal conductivity), of electrical properties (e.g., ohmic resistance or permittivity), of magnetic properties (e.g., magnetic permeability or inductivity) and of chemical properties (e.g., corrosion resistance or chemical reactivity) for the first and second states 34a, 34b.

(13) As a result, the first and second states 34a, 34b differ in their mechanical, thermal, electrical and/or chemical properties. Hence, the information code pattern 36 being defined by the first and second states/values 34a, 34b is also mechanically readable, for example, by a position resolved hardness measurement technique, such as material deformation due to monotonic loading, thermally readable, for example, by a position resolved thermal conductivity measurement technique, electrically readable, for example, by a position resolved electrical (ohmic) resistance measurement technique or by an eddy current measurement technique, and chemically readable, for example, by a position resolved chemical reactivity measurement technique.

(14) If desired, the control unit 28 may control the carrier 14, the powder application device 16 and the irradiation device 20 in dependence on the crystallization behavior of tire raw material powder 18, in order to tailor the microstructure 34 of the work piece 12 made of the raw material powder 18 by an additive construction method such that the, for example, first state 34a of the physically determinable microstructure parameter is restricted to a spatial portion 35a completely inside the completed work piece 12 (see FIG. 2). In this case, the information code pattern 36 is not visible from outside the work piece 12, but readable by material penetrating measuring techniques such as a position resolved eddy current measurement technique.

(15) FIG. 2 shows a three-dimensional sample work piece 12 containing an information code pattern 36 which is generated by the apparatus 10 of FIG. 1, wherein the apparatus 10 may comprise an irradiation device 20 having two laser irradiation sources 24. A first laser radiation source may emit electromagnetic radiation of 1000 W power, wherein a second laser radiation source may emit electromagnetic radiation of 400 W power so as to produce the spatial portions 35a and 35b of the work piece 12 which are irradiated by the first 1000 W laser radiation source and the second 400 W laser radiation source, respectively (see FIG. 2). Depending on the laser radiation source employed, a layer thickness of the raw material powder during manufacturing may be between 50 m and 150 m. The control unit (not shown) of the apparatus 100 may control the process parameters such that a similar energy density is provided to the raw material powder irrespective of the power of the first and the second laser radiation source.

(16) For appropriate use of the here suggested labeling method, it should be clearly distinguished between the two different microstructures (black and white). FIG. 3 depicts a hardness map obtained in the sample gauge length (BD; horizontal axis). As shown, the mean hardness values (HV; vertical axis) differ significantly for the two microstructures (black and white), revealing a value of about 215 HV for the fine-grained regions 35b (white; 400 W) and 190 HV for the columnar coarse-grained region 35a (black; 1000 W).

(17) The complexity of the embedded information code pattern 36 can be easily increased. For example, the shape of wither region (black and white, respectively) can be directly manipulated. As another example, the information code pattern 36 can be introduced in any area of the work piece 12, such as even beneath the outer surface the work piece 12, which is not visible by naked-eye inspection. In turn, highly loaded areas of the work piece 12, may not be suited for labeling, since the microstructure of a modified section may lead to inferior mechanical properties, e.g. in terms of yield strength of a columnar coarse-rained region. Thus, placement of the information code pattern 36 may also require thorough load distribution analyses and, if necessary, adaptation of the geometry of the work piece 12, in order to fully preserve the load bearing capacity of each single section of the work piece 12.