Method and device for the production of a three-dimensional object by means of sintering

1. A process for producing a three-dimensional object by layer-wise solidification of a pulverulent material by sintering of the material at points corresponding to the cross-section of the object by means of the action of radiation energy, the process comprising the steps of:

applying a layer of the pulverulent material to a substrate or a previously sintered layer;

pre-heating the pulverulent material to a working temperature (T A ) below the temperature at which the powder is sintered;

sintering of the material at the points corresponding to the cross-section of the object in the layer;

and

repeating the steps of applying a layer, pre-heating and sintering until the object is completed;

wherein, during said process for producing a three-dimensional object, the specific thermal capacity C P (T) of the pulverulent material is established on an applied powder layer before at least one sintering step by determining the quantity of heat taken up per temperature interval (dQ/dT) for at least two temperature intervals, and

wherein the process includes controlled heating of an applied powder layer for determining the quantity of heat (Q) taken up by the powder per temperature interval for at least two temperature intervals.

2. The process according to claim 1 , further comprising determining a material-specific temperature (T characteristic ) of the pulverulent material.

3. The process according to claim 2 , wherein the material-specific temperature is a temperature selected from the group consisting of a melting temperature, a glass transition temperature and an onset temperature.

4. The process according to claim 2 , further comprising adjusting the working temperature (T A ) so that it lies below an said determined material-specific temperature (T characteristic ) by a preset temperature interval (ΔT red ).

5. The process according to claim 1 , further comprising determining the power of the radiation source required for sintering as a function of the quantity of heat taken up per temperature interval.

6. The process according to claim 1 , further comprising controlling or regulating the heating power of a heating device used for pre-heating as a function of the quantity of heat taken up per temperature interval.

7. The process according to claim 1 , further comprising the step of determining the quantity of heat taken up by the powder per temperature interval is carried out during the producing of the object.

8. The process according to claim 1 , further comprising providing a laser as a radiation source.

9. The process according to claim 1 , further comprising providing a plastic powder for the pulverulent material.

10. The process according to claim 9 , wherein the plastic material comprises a polyamide or a polystyrene.

11. The process according to claim 1 , further comprising determining a material-specific temperature (T characteristic ) of the pulverulent material from a change of the quantity of heat taken up per temperature interval.

12. The process according to claim 1 , further comprising adjusting the working temperature (T A ), to which the powder is to be pre-heated, as a function of the change ascertained.