Method for determining building instructions for an additive manufacturing method, method for generating a database with correction measures for controlling the process of an additive manufacturing method

1. A method for determining building specifications describing process control for the additive manufacturing of a building structure on the basis of a simulation of the manufacture of the building structure, the method comprising:

accessing a manufacturing data set for the building structure, the manufacturing data set describing the building structure in layers to be manufactured;

calculating a global heat development in already manufactured layers of the building structure based at least in part on a building history of the building structure and heat input by an energy beam;

determining a local heat development in a vicinity of the heat input by the energy beam;

determining the process control based at least in part on the global heat development and the local heat development;

loading correction measures of the process control from a database based at least in part on the global heat development and the local heat development; and

assigning the correction measures locally to individual vectors of a tool path of the energy beam; wherein

at least one mass integral is calculated for individual vectors of the tool path; and

correction measures are determined on the basis of a comparison of the calculated mass integral with mass integrals stored in the database.

2. The method as claimed in claim 1 , wherein the correction measures of the process control are determined in such a way that a melt pool produced by the energy beam has a size that is in a defined interval.

3. The method as claimed in claim 1 , further comprising calculating a mass integral for individual vectors of the tool path over a defined integration volume;

wherein the integration volume contains a part of the surface of the building structure facing the energy beam; and

wherein a point of the vector considered lies in the integration volume.

4. The method as claimed in claim 3 , further comprising calculating at least one mass integral at the beginning and one mass integral at the end of the vector for the vectors.

5. The method as claimed in claim 4 , further comprising selecting, from the mass integrals calculated per vector, a mass integral with a lowest value.

6. The method as claimed in claim 4 , further comprising calculating a value corresponding to a mean value of the mass integrals from the mass integrals calculated per vector.

7. The method as claimed in claim 3 , wherein in order to determine the correction measures for a vector considered:

the calculated mass integral is compared with mass integrals stored in the database;

that stored mass integral most similar to the calculated mass integral is selected from the database; and

the correction measures of the process control stored with the selected mass integral are selected for the vector considered.

8. The method as claimed in claim 3 , wherein to determine the correction measures in the form of correction values for a vector considered:

the calculated mass integral is compared with mass integrals stored in a database;

those stored mass integrals which are the most similar to the calculated mass integral are selected from the database; and

the correction values for process parameters of the process control stored with the selected mass integrals are selected for the vector considered and an interpolation of said correction values is carried out, wherein the result of the interpolation is used as a resulting correction value for the correction.

9. The method as claimed in claim 3 , wherein the mass integral has the shape of an ellipsoid or of a semi-ellipsoid having a semi-axis δr in the x-y-plane of the layer to be manufactured and δz in the z-direction.

10. The method as claimed in claim 1 , wherein the correction measures include at least one of: a reduction of the power of the energy beam, a lengthening of the pause times between the irradiation times of individual vectors, an increase of the movement speed of the energy beam, an increase of the hatch distance between the vectors, an alteration of the vector order, an alteration of the vector length, an alteration of the vector orientation.

11. A method for determining correction measures for building specifications describing process control for additive manufacturing of building structures on the basis of a simulation, the method comprising:

defining process parameters for the process control are defined;

accessing a manufacturing data set for the building structure, said manufacturing data set describing the building structure in layers to be manufactured;

assessing a global heat development in the form of a reference temperature;

calculating local heat development in the vicinity of the heat input by an energy beam;

calculating the local heat development in the vicinity of the heat input by the energy beam for representative volume elements with a predefined geometry;

if a calculated heat development exceeds a threshold, assigning correction measures of the process control locally to individual vectors of a tool path of the energy beam;

calculating a mass integral over a partial volume of the representative volume element in which the correction measures are required; and

storing the correction measures with the associated mass integral in a database.

12. The method as claimed in claim 11 , wherein the representative volume elements have the shape of

parallelepipeds,

prisms having two lateral surfaces extending parallel to the layers and at least one lateral surface extending at an inclination to the layers and connecting the parallel lateral surfaces, and/or

triangular prisms having a lateral surface extending parallel to the layers.

13. The method as claimed in claim 11 , further comprising using a parallelepipedal representative volume element, the boundary of which is surrounded all around by the material of the building structure, to ascertain reference values for the process control;

wherein the correction parameters aim to reduce the energy input of the energy beam.

14. The method as claimed in claim 11 , further comprising calculating a melt pool size by calculating the mass integral over a partial volume of the representative volume element containing a part of the surface of the representative volume element facing the energy beam, localized on a plurality of points of the tool path;

wherein for said points the melt pool size is calculated taking account of the local heat development and the reference temperature.

15. The method as claimed in claim 11 , wherein the mass integral has the shape of an ellipsoid or of a semi-ellipsoid having a semi-axis δr in the x-y-plane of the layer to be manufactured and δz in the z-direction.