Process for the Accelerated Production of Objects by Means of Generative Manufacturing

Patent metadata

Field	Value
Publication number	US-2016279872-A1
Application number	US-201415037109-A
Country	US
Kind code	A1
Filing date	Dec 1, 2014
Priority date	Dec 2, 2013
Publication date	Sep 29, 2016
Grant date	—

Abstract

A process for the layer-by-layer construction of a three-dimensional object (3) from a pulverulent construction material by means of successively solidifying layers of the pulverulent construction material in each case at those sites of a layer which correspond to a cross section of the object, wherein the solidification is accomplished by introducing heat energy, has the following steps for each layer: a step of providing a layer of a pulverulent construction material, a step of preheating the applied construction material to a preheating temperature, below the temperature at which the material is solidified, and a step of solidifying the applied layer by means of electromagnetic radiation or particle radiation (7), wherein, in the solidification step, during a predetermined period of time, the start of which coincides with the beginning of the solidification step, the quantity of heat introduced per unit area is reduced over time and can be described by a function which decreases monotonously depending on the time.

First claim

1 . A method for a layer-wise construction of a three-dimensional object from a building material in powder form by means of a sequential solidification of layers of the building material in powder form at those positions of a layer that correspond to the cross-section of the object, wherein the solidification is effected by introducing heat energy and the method for each layer comprises the following steps:
a step of providing a layer of a building material in powder form on a building support or a layer that has been previously solidified at selected positions, a step of pre-heating the applied building material up to a pre-heating temperature below the temperature at which the material is solidified and a step of solidifying the applied layer by means of electromagnetic radiation or particle radiation, in which step a solidification radiation incidence region sequentially sweeps over all positions of the layer corresponding to the cross-section of the object so that the powder at these positions is solidified by the heat energy introduced by the radiation, characterized in that in the solidification step the heat energy introduced per unit area in the solidification radiation incidence region is reduced with time during a predetermined period the start of which coincides with the start of the solidification step and can be described by a function monotonically decreasing with time.

2 . The method according to claim 1 , in which the solidification is effected by means of at least one photon or particle beam that is directed sequentially onto positions of the layer to be solidified.

3 . The method according to claim 1 , in which the solidification is effected by means of electromagnetic radiation and the solidification radiation incidence region is an area.

4 . The method according to claim 1 , in which the monotonically decreasing function is empirically determined by determining in pre-tests the temperature change of the building material layer for a heating-up to temperatures below the temperature at which the solidification is carried out, in which pre-tests
a plurality of objects to be manufactured or a plurality of test specimens is manufactured, cross-sections of the objects to be manufactured or of the test specimens are solidified at different points in time from the start of the solidification step of a layer and after the end of the building process a property of the objects or test specimens to be manufactured is determined and the mentioned function, according to which the heat amount introduced per unit area is reduced during the predetermined period and the length of the predetermined period are determined based on the determined property of the objects ( 3 ) or test specimens to be manufactured.

5 . The method according to claim 4 , in which the property determined at the objects or test specimens to be manufactured is a mechanical property, a dimension or a parameter for describing the surface quality.

6 . The method according to claim 1 , in which the heat amount introduced per unit area is reduced by reducing the radiant flux in the solidification radiation incidence region that is sweeping over the powder.

7 . The method according to claim 1 , in which the heat amount introduced per unit area is reduced by an increase of the velocity with which the solidification radiation incidence region sweeps over the powder layer.

8 . A device for a layer-wise construction of a three-dimensional object according to a method according to claim 1 , wherein the device comprises:
a building support for carrying the object to be formed; an application device for applying a layer of the building material in powder form onto the surface of the support or an already at least partially solidified layer, a heating device, which is able to supply heat energy for an areal pre-heating of the building material layer in powder form, an irradiation device that emits electromagnetic radiation or particle radiation and is able to sweep with a solidification radiation incidence region sequentially over all positions of the layer that correspond to the cross-section of the object, such that the powder at these positions is solidified by the heat energy introduced by the radiation, and a control device that controls the device for a layer-wise construction such that after a lowering of the building support by an amount corresponding to a layer thickness, the application device applies a layer of the building material in powder form onto the building support or a layer that has already been solidified at selected positions, and subsequently the irradiation device solidifies the building material in powder form in a region corresponding to a cross-section of the object by sweeping a solidification radiation incidence region sequentially over all positions of the layer corresponding to the cross-section of the object such that the powder at these positions is solidified by the heat energy introduced by the radiation, wherein the control device controls the irradiation device such that during a predetermined period from the start of the solidification of the powder in a powder layer by the irradiation device the heat amount introduced per unit area into the building material in powder form by the irradiation device in the solidification radiation incidence region decreases in correspondence to a function decreasing monotonically with time.

9 . The device according to claim 8 having a temperature measuring device that is able to make a contactless measurement of the temperature of a partial region of a powder layer.

Assignees

• Eos Gmbh Electro Optical Systems

Inventors

• Paternoster Stefan

Classifications

• B33Y10/00

  Processes of additive manufacturing · CPC title

• B29C64/393

  for controlling or regulating additive manufacturing processes · CPC title

• B33Y50/02

  for controlling or regulating additive manufacturing processes · CPC title

• B28B1/001

  Rapid manufacturing of 3D objects by additive depositing, agglomerating or laminating of material (selective deposition modelling of metallic powder B22F10/00; rapid manufacturing of 3D objects in general and in particular of plastics B29C64/00) · CPC title

• B29C64/40

  Structures for supporting 3D objects during manufacture and intended to be sacrificed after completion thereof · CPC title