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CN-121972688-A - Power regulation and control method for accurate coupling of length of scanning vector of two-dimensional section and energy density in additive manufacturing

CN121972688ACN 121972688 ACN121972688 ACN 121972688ACN-121972688-A

Abstract

The invention discloses a power regulation and control method for accurately coupling scanning vector length and energy density of a two-dimensional section in additive manufacturing, which adopts a dynamic regulation and control strategy of laser energy density for regulating and controlling the coupling of the scanning vector length and the laser energy density to accumulate layer by layer to prepare a two-dimensional variable-section complex component, wherein in the forming process, the dynamic regulation and control strategy of the laser energy density takes the scanning vector length as a minimum regulation and control unit, and regulates and controls laser power in real time according to different scanning vector lengths corresponding to different sections obtained by slicing the two-dimensional variable-section complex component until the last layer is deposited to finish printing. Therefore, the invention can achieve the purposes of improving the forming quality, controlling the linearity of the technological parameters, effectively inhibiting the defects and forming the complex components in a high-precision integrated manner.

Inventors

  • DAI DONGHUA
  • XING ZHENHONG
  • CHEN TAO

Assignees

  • 南京航空航天大学

Dates

Publication Date
20260505
Application Date
20251231

Claims (10)

  1. 1. A power regulation and control method for precisely coupling the length of a scanning vector of a two-dimensional section with the energy density of additive manufacturing is characterized in that a dynamic regulation and control strategy of the laser energy density, which is used for regulating and controlling the coupling of the length of the scanning vector and the energy density of laser, is adopted to prepare a two-dimensional variable-section complex component layer by layer in an accumulated manner; in the forming process, the dynamic regulation strategy of the laser energy density takes the scanning vector length as a minimum regulation unit, and regulates and controls the laser power in real time according to different scanning vector lengths corresponding to different sections obtained by slicing the two-dimensional variable-section complex component, so as to control the laser energy density input and monitor the center temperature of a molten pool, ensure that the heat input amounts of different scanning vector positions are consistent, reduce the energy input amount difference of the scanning vector positions corresponding to the different scanning vector lengths until the last layer is deposited, and finish printing.
  2. 2. The method for adjusting and controlling the power of accurate coupling of the length of a scanning vector of a two-dimensional cross section of additive manufacturing and energy density according to claim 1, wherein in the forming process, the dynamic adjusting and controlling strategy of the laser energy density dynamically adjusts and controls the laser power in the moving process of a vibrating mirror through an energy density adjusting and controlling function, and the energy density adjusting and controlling function is expressed as follows: ; P t represents laser power set values applied at different positions under the current scanning vector length, P 0 represents a power preset value, F (x) represents a power regulation equivalent substitution function, b represents a laser power error coefficient, and gamma represents an energy density error coefficient; the power regulation equivalent substitution function F (x) is expressed as follows: ; ; in the above formula: The method comprises the steps of expressing a galvanometer motion equation, d expressing a laser spot diameter, ρ expressing a powder bed stacking density, C p expressing a specific heat capacity, T m expressing a material melting point, T 0 expressing an ambient temperature, L m expressing a material melting latent heat, alpha eff expressing an effective powder absorption coefficient related to a powder bed stacking state, k eff expressing an effective powder bed heat conduction coefficient, h expressing a powder bed thickness, T peak expressing a molten pool center temperature, and h conv expressing a convective heat transfer coefficient.
  3. 3. The method for regulating and controlling the power of accurate coupling of the length of a scanning vector of a two-dimensional section of additive manufacturing and energy density according to claim 2, wherein the motion equation of a galvanometer is a scanning speed change function related to the position x of the scanning vector; When the scanning vector length of the laser During the acceleration, uniform speed and deceleration phases of the vibrating mirror exist, wherein: the equation of motion during the galvanometer acceleration phase is expressed as: ; The equation of motion at the galvanometer deceleration stage is expressed as: wherein Indicating the position of the deceleration phase of the galvanometer, Representing the position corresponding to the cut-off moment of the vibrating mirror acceleration stage; the equation of motion of the vibrating mirror during uniform motion is recorded as Constant preset value for scanning speed Expressed as: ; When the scanning vector length of the laser The method only comprises the stage of acceleration and deceleration of the vibrating mirror, wherein: the equation of motion during the galvanometer acceleration phase is expressed as: ; The equation of motion at the galvanometer deceleration stage is expressed as: , ; a is a quadratic term fitting coefficient, and c is a first order quadratic term fitting coefficient.
  4. 4. The method for power regulation and control of accurate coupling of scan vector length and energy density of two-dimensional cross section of additive manufacturing according to claim 2, wherein the energy density error coefficient γ is quantitatively calibrated during the forming process, and the energy density error coefficient γ in the energy density regulation and control equation is corrected according to the following rule: when delta is 3 percent and 10 percent, the single regulation amplitude delta of gamma is less than or equal to 0.05; When delta is 10 percent and 20 percent, the single regulation amplitude delta of gamma is less than or equal to 0.10; when delta is 20 percent and 30 percent, the single regulation amplitude delta of gamma is less than or equal to 0.15; wherein delta represents the temperature difference rate, and the calculation formula is as follows: ; ; in the above formula: representing the actual monitored bath center temperature; a molten bath center temperature for the corresponding position calculated based on the molten bath center temperature calculation model, the molten bath center temperature calculation model being expressed as: ; in the above formula: a calculation value representing the bath center temperature at the scan vector position x; representing ambient temperature; Indicating the effective absorption coefficient of the powder in relation to the state of accumulation of the powder bed; Representing the laser power; representing the diameter of a laser spot; Representing the bulk density of the powder bed; Representing a galvanometer motion equation; Represents the specific heat capacity; Represents the melting point of the material; indicating the latent heat of fusion of the material; Indicating the effective heat conductivity coefficient of the powder bed; representing the powder bed thickness; representing the convective heat transfer coefficient.
  5. 5. The power regulation and control method for accurately coupling the length of a scanning vector of a two-dimensional section with the energy density for additive manufacturing according to claim 1, wherein a dynamic regulation and control strategy for the energy density of laser is constructed by the following steps: extracting the central temperature and position information of a molten pool in the single-channel deposition process, and fitting to obtain a galvanometer motion equation ; Based on the obtained galvanometer motion equation Combining the relation between the laser power and the laser energy density to construct a temperature change function And simplify to obtain the central temperature of the molten pool Is calculated according to the formula; based on the obtained temperature variation function Combining the center temperature of the molten pool measured by the test to obtain a relation function of the laser power and the scanning vector position ; Relation function based on laser power and scanning vector position correlation Extracting dimensionless power regulation equivalent substitution function ; Equivalent substitution function of power regulation Introducing into the simulation model heat source code to provide an accuracy adjustment error coefficient so that the extracted molten pool center temperature is matched with experimental data to match the temperature difference rate Controlling the accuracy adjustment error coefficient to be within 3 percent, wherein the accuracy adjustment error coefficient comprises a power correction coefficient And error coefficient ; Based on the obtained power correction coefficient And error coefficient Construction of equivalent Power Regulation function ; Based on the obtained equivalent power regulation function Construction of an energy density control equation ; Based on the constructed energy density regulation equation Constructing energy density regulating function to calculate output actual power set value 。
  6. 6. The method for adjusting and controlling power by precisely coupling length of scanning vector of two-dimensional cross section with energy density for additive manufacturing according to claim 5, wherein the function of temperature variation Expressed as: ; in the above formula: representing ambient temperature; Indicating the effective absorption coefficient of the powder in relation to the state of accumulation of the powder bed; Representing the laser power; representing the diameter of a laser spot; Representing the bulk density of the powder bed; Representing a galvanometer motion equation; Represents the specific heat capacity; Represents the melting point of the material; indicating the latent heat of fusion of the material; Indicating the effective heat conductivity coefficient of the powder bed; representing the powder bed thickness; Representing the convective heat transfer coefficient; Representing the distance from the center of the bath; representing coefficients related to the shape of the bath.
  7. 7. The method for adjusting and controlling the power of the precise coupling of the length of the scanning vector and the energy density of the two-dimensional cross section of the additive manufacturing according to claim 6, wherein the relation function of the laser power and the position of the scanning vector is related Expressed as: ; equivalent substitution function for power regulation The expression is as follows: ; ; in the above formula: Representing a galvanometer motion equation; representing the diameter of a laser spot; Representing the bulk density of the powder bed; Represents the specific heat capacity; Represents the melting point of the material; representing ambient temperature; indicating the latent heat of fusion of the material; Indicating the effective absorption coefficient of the powder in relation to the state of accumulation of the powder bed; Indicating the effective heat conductivity coefficient of the powder bed; representing the powder bed thickness; indicating the center temperature of the molten pool; representing the convective heat transfer coefficient.
  8. 8. The method for regulating and controlling power by accurately coupling length of scanning vector of two-dimensional cross section with energy density for additive manufacturing according to claim 7, wherein the temperature difference rate is as follows Calculated by the following formula: ; ; in the above formula: representing the actual monitored bath center temperature; a molten bath center temperature for the corresponding position calculated based on the molten bath center temperature calculation model, the molten bath center temperature calculation model being expressed as: ; in the above formula: representing scan vector position A calculated bath center temperature; representing ambient temperature; Indicating the effective absorption coefficient of the powder in relation to the state of accumulation of the powder bed; Representing the laser power; representing the diameter of a laser spot; Representing the bulk density of the powder bed; Representing a galvanometer motion equation; Represents the specific heat capacity; Represents the melting point of the material; indicating the latent heat of fusion of the material; Indicating the effective heat conductivity coefficient of the powder bed; representing the powder bed thickness; representing the convective heat transfer coefficient.
  9. 9. The method for regulating and controlling power by accurately coupling length of scanning vector of two-dimensional cross section with energy density for additive manufacturing according to claim 8, wherein the equivalent power regulating and controlling function Expressed as: ; the energy density control equation P (x) is expressed as: ; Actual power set point Calculated by the following formula: ; in the above formula: As a function of the power correction factor, As a coefficient of the laser power error, Equivalent substitution function for power regulation; is an equivalent power regulation function An inverse function of (2); is an energy density error coefficient; The power is preset.
  10. 10. The method for regulating and controlling the power of the accurate coupling of the scanning vector length and the energy density of the two-dimensional section of the additive manufacturing according to claim 1 is characterized in that in the forming process, laser process parameters are that a power preset value P 0 =200W and a scanning speed v=1000 mm/s, and the used metal powder is high-specific gravity tungsten alloy powder and comprises the following components of 98wt.% W, 1.4wt.% Ni and 0.6wt.% Fe.

Description

Power regulation and control method for accurate coupling of length of scanning vector of two-dimensional section and energy density in additive manufacturing Technical Field The invention relates to a power regulation and control method for accurately coupling the length of a scanning vector of a two-dimensional section with energy density in additive manufacturing, and belongs to the technical field of laser powder bed melting additive manufacturing. Background The laser powder bed melting (LPBF) is an important component part of the additive manufacturing technology, combines part model design, selectively scans and melts deposited metal powder layer by layer based on high-energy laser beams, realizes integrated forming of complex components, and has the advantages of no need of a die, high forming freedom, short process route, integrated digital forming and the like compared with the traditional machining mode. However, based on the processing characteristics of a high-energy laser beam that allows a material to be melted and solidified by inputting a large amount of energy in a short time, a series of thermal defects, such as cracks, etc., caused by heat accumulation are inevitably generated in practical applications. In the laser additive manufacturing process, a loading position of a laser beam is adjusted through a vibrating mirror, so that the phenomenon that the scanning vector length difference exists in the slicing process of a two-dimensional variable cross section is inevitable, the movement process of the vibrating mirror is an acceleration and deceleration process, namely, under the same power/energy density, the difference exists between the heat input quantity in the same time in the acceleration and deceleration process of the vibrating mirror and the heat input quantity in the uniform movement process of the vibrating mirror, and therefore, the defects of high temperature gradient generated in the laser processing process, large heat accumulation and further heat defect generation probability are increased, and meanwhile, for a component with an edge variable angle, the large probability of the acceleration and deceleration process of the vibrating mirror occurs at the edge positions and the variable angle positions in the height direction, and the component generates large heat stress under the action of high heat accumulation, so that the component generates warping and the like are amplified. If the defects of the edges of the components are reduced by simply regulating and controlling the power, the probability of the defects such as unfused holes in the internal deposition process is increased, so that the laser energy density of the two-dimensional variable-section component with the variable vector length needs to be regulated and controlled in real time in a targeted manner, the defects such as cracks and warpage generated in the acceleration and deceleration process of the edge vibrating mirror are reduced, and meanwhile, the good internal deposition quality is ensured, so that the aim of accurately regulating and controlling the energy density of the two-dimensional variable-section vector with different lengths and different positions is fulfilled. Disclosure of Invention The invention aims to provide a power regulation and control method for accurately coupling the length of a scanning vector of a two-dimensional section with energy density in additive manufacturing, so that the energy density of different positions of vectors with different lengths of a two-dimensional complex section can be accurately regulated and controlled, and the purposes of parameter controllability, performance optimization and defect inhibition can be achieved. In order to achieve the technical purpose, the invention adopts the following technical scheme: A power regulation and control method for accurately coupling scanning vector length and energy density of two-dimensional cross section in additive manufacturing adopts a dynamic regulation and control strategy of laser energy density for regulating and controlling the coupling of scanning vector length and laser energy density to prepare a two-dimensional variable cross section complex component layer by layer in an accumulated manner; In the forming process, the dynamic regulation strategy of the laser energy density takes the scanning vector length as a minimum regulation unit, and the laser power is regulated and controlled in real time according to different scanning vector lengths corresponding to different sections obtained by slicing the two-dimensional variable-section complex component, so as to control the laser energy density input until the last layer is deposited, and the printing is completed. Preferably, in the forming process, the dynamic regulation strategy of the laser energy density dynamically regulates the laser power in the vibrating mirror motion process through an energy density regulation function, and the energy density