Control unit for pulsed irradiation in additive manufacture
A method for the computer-aided provision of control instructions for pulsed irradiation in the additive production of a component structure includes establishing process parameters, including a pulse frequency, a pulse width, a scan speed, and an irradiation power; defining the pulse frequency and scan speed as process constants; and determining parameter values of the pulse width and of the irradiation power from the process constants which have been defined. A corresponding computer program product, a method for bed-based additive production, and a corresponding control device are adapted for pulsed irradiation in the additive production of a component structure.
1 . A method for additive production of a component structure, comprising:
a) providing, via a computer, control instructions (f, τ, v, P) for pulsed irradiation, comprising:
i) establishing process parameters, comprising a pulse frequency (f), a pulse width (τ), a scan speed (v) and an irradiation power (P),
ii) defining the pulse frequency (f) and scan speed (v) as process constants and defining a melt pool overlap (o) as a process constant, wherein the melt pool overlap (o) is based on parameter values of the established process parameters, and
iii) determining parameter values of the pulse width (τ) and of the irradiation power (P) from the process constants which have been defined;
b) executing the control instructions for the additive production of the component structure comprising generating an energy beam along an irradiation path (V) including generating consecutive pulses of the pulsed irradiation along the irradiation path (V) and generating consecutive melt pools along the irradiation path (V) wherein the consecutive melt pools have the melt pool overlap (o) along the irradiation path (V).
2 . The method as claimed in claim 1 ,
wherein a value of the pulse frequency (f) between 1 kHz and 25 kHz is selected.
3 . The method as claimed in claim 1 ,
wherein a value of the irradiation power (P) between 50 W and 300 W is determined such that the value of the irradiation power (P) is above a first threshold to ensure sufficient melting of a powder bed and below a second threshold to avoid material evaporation, pores or cavities in the component structure.
4 . The method as claimed in claim 1 , wherein the consecutive melt pools have the melt pool overlap (o) along the irradiation path (V) that is above a threshold value to achieve a homogeneous and coherent component structure.
5 . The method as claimed in claim 1 ,
wherein the melt pool overlap (o) comprises;
a pathwise melt pool overlap based on parameter values of the pulse width (τ), pulse frequency (f) and scan speed (v), and
a layerwise melt pool overlap based on a value of the irradiation power (P).
6 . The method as claimed in claim 1 ,
wherein a geometry of the component structure is divided into layers and wherein the pulse frequency (f) and scan speed (v) are defined as process constants with each of the divided layers.
7 . The method as claimed in claim 1 ,
wherein a duty cycle of between 25% and 75% is selected for the pulsed irradiation.
8 . The method as claimed in claim 1 ,
wherein a value of the scan speed (v) between 100 mm/s and 3000 mm/s is selected.
9 . The method as claimed in claim 1 ,
wherein with an increasing defined pulse frequency (f), a lower irradiation power (P) and a smaller pulse width (τ) are determined.
10 . A computer program product stored on a non-transitory computer readable media, comprising:
commands which, when executed by a computer, cause this computer to carry out the method as claimed in claim 1 .
11 . A control device for the additive production of a component structure,
wherein the control device is configured to employ the control instructions provided by the method as claimed in claim 1 in order to control an energy beam of an additive production apparatus in the course of the additive production of the component structure.
12 . An additive production apparatus, comprising:
a control device as claimed in claim 11 ;
a construction platform;
a powder bed;
a coater configured to distribute powder from the powder bed layerwise on the construction platform;
a beam source of the energy beam;
wherein the control device is configured to employ the control instructions to control the energy beam along an irradiation path (V) such that the executing step (b) comprises generating the energy beam with consecutive pulses of the pulsed radiation and generating consecutive melt pools with the consecutive pulses in each layer of the powder bed on the construction platform such that the consecutive melt pools have a melt pool overlap (o) along the irradiation path (V) based on the determined parameter values of the pulse width and the irradiation power and such that the melt pool overlap (o) is above a threshold value to achieve a homogeneous and coherent component structure.
13 . The method as claimed in claim 7 ,
wherein a duty cycle of 50% is selected for the pulsed irradiation.
14 . The computer program product as claimed in claim 10 ,
wherein the commands control the irradiation in an additive production apparatus.
15 . The control device as claimed in claim 11 ,
wherein the energy beam comprises a laser beam.
16 . The method as claimed in claim 1 , wherein a value of the melt pool overlap (o) is based on a value of the pulse width and wherein the value of the pulse width is selected such that the value of the melt pool overlap (o) is sufficient to bring about a homogeneous or coherent structure of the component in the executing step b).
17 . The method as claimed in claim 16 , wherein the executing step b) comprises generating individual pulses having a respective length along an irradiation path which produce respective melt pools with the same respective length along the irradiation path, wherein the respective melt pools overlap by the melt pool overlap (o).
18 . The method as claimed in claim 5 ,
wherein a value of the pathwise melt pool overlap is based on a value of the pulse width and wherein the value of the pulse width is selected such that the value of the melt pool overlap (o) is above a threshold value to bring about a homogeneous or coherent structure of the component in the executing step b); and
wherein a value of the layerwise melt pool overlap is based on a value of the irradiation power and wherein the value of the irradiation power is above a threshold value to bring about a homogeneous or coherent structure of the component in the executing step b).
19 . The method as claimed in claim 17 , wherein the respective melt pools are elliptical in shape and wherein the melt pool overlap is a lenticular or circular region.
20 . A method for additive production of a component structure, comprising:
a) providing, via a computer, control instructions (f, τ, v, P) for pulsed irradiation, comprising:
i) establishing process parameters, comprising a pulse frequency (f), a pulse width (τ), a scan speed (v) and an irradiation power (P),
ii) defining the pulse frequency (f), the scan speed (v) as process constants which have constant values during the method, and
iii) determining parameter values of the pulse width (τ) and of the irradiation power (P) from the constant values of the process constants which have been defined;
b) executing the control instructions for the additive production of the component structure including generating an energy beam along an irradiation path (V) including generating consecutive pulses of the pulsed radiation along the irradiation path (V) and generating consecutive melt pools along the irradiation path (V) with the consecutive pulses, wherein the consecutive melt pools have a melt pool overlap (o) along the irradiation path (V) based on the determined parameter values of the pulse width and the irradiation power such that the melt pool overlap (o) along the irradiation path (V) is above a threshold value to achieve a homogeneous and coherent component structure.