CN116079074A

CN116079074A - Variable-angle conformal laser selective material-increasing manufacturing method

Info

Publication number: CN116079074A
Application number: CN202310059976.5A
Authority: CN
Inventors: 杜家龙; 鲁金忠; 陆旻炜; 张红梅; 罗开玉
Original assignee: Jiangsu University
Current assignee: Jiangsu University
Priority date: 2023-01-20
Filing date: 2023-01-20
Publication date: 2023-05-09

Abstract

The invention discloses a variable angle conformal laser selective area additive manufacturing method, which comprises the steps of discretizing a workpiece model slice plane by using dynamic conformal slice processing; the growth rotation angle between slice planes is adjusted by restraining the thickness of the conformal slice layer, and the conformal slice layer is scattered into a series of conformal slice layers with different angles and thicknesses according to the shape of a formed workpiece. Forming a workpiece by adopting an inverted laser mode on the basis; the laser beam is used for melting or sintering the selected area of the powder layer from the lower part through the high-temperature-resistant glass, and the workpiece is manufactured layer by layer from top to bottom. According to the method, multi-degree-of-freedom direction layered data processing can be realized according to the shape of the formed workpiece, and the information of each conformal slice layer can be independently adjusted, so that the preparation of a complex shape structure is realized, and the use of an additional supporting structure in the material adding process is avoided.

Description

Variable-angle conformal laser selective material-increasing manufacturing method

Technical Field

The invention relates to a laser additive processing technology, in particular to a variable-angle conformal laser selective additive manufacturing method.

Background

The laser selective melting (SLM) and laser selective sintering (SLS) technologies utilize laser beams to directly manufacture the preset powder into the three-dimensional solid piece according to model data, and the method is suitable for various engineering applications in a plurality of key industrial fields such as aerospace, aviation, automobiles, biomedicine, molds and the like due to high molding accuracy, good surface quality and few subsequent procedures.

At present, a plane slicing and layering strategy is generally adopted in laser selective area additive manufacturing, namely, a three-dimensional model is sliced along the z axis of the height direction of a workpiece, so that a group of horizontal slice layers are generated on an x-y plane. These layers are stacked one on top of the other to create the sliced layers required for the additive process, however the traditional additive approach employing planar layer-by-layer printing strategies has limited flexibility in terms of customization and multi-material integration. The freedom to print complex geometries is also limited.

Chinese patent with patent grant publication No. CN 209918884U discloses an additive manufacturing apparatus for high-degree-of-freedom complex structural parts, which can effectively prepare high-degree-of-freedom complex structural parts through three-dimensional space positioning auxiliary support, but is not adjusted for a forming method. The Chinese patent with the patent grant publication number of CN 109501272B provides a layering method for a hanging feature structure in additive manufacturing and an additive manufacturing method thereof, wherein the thickness and layering of layers are adjusted through the angle proportion of triangular surfaces in Z-direction layering of a statistical model, so that the forming precision and quality are improved, but the method still adopts a Z-direction slicing layering mode, does not adjust the additive manufacturing direction, and cannot adapt to high-precision manufacturing of large-area-rate workpieces. The Chinese patent with the patent grant publication number of CN 111941826B provides a block additive manufacturing method of complex parts, wherein a part model to be processed is used for adjusting the placement posture of sub-blocks according to whether the sub-blocks can be printed or not, and a plurality of sub-blocks are spliced to finish part manufacturing, so that a new idea is provided for complex geometric construction additive manufacturing.

Disclosure of Invention

Aiming at the problems, the invention provides a variable-angle conformal laser selective area additive manufacturing method, which is realized through the following technical steps:

s1, carrying out dynamic shape-following slicing treatment on a three-dimensional model of a formed workpiece, discretizing a slice plane of the three-dimensional model of the formed workpiece, and acquiring shape-following slice layers and related coordinate information from top to bottom. Wherein the slice plane is defined as K _i I=0, 1,2, … … for slice plane K _i And K is equal to _i+1 The conformal slice layer of the formed workpiece between is defined as P _i ，i＝0,1,2,……。

Step S1 is subdivided into the following steps:

step 1, unlike the traditional Z-direction plane equidistant slicing, the dynamic shape-following slicing treatment sets the plane with the highest height direction of the formed workpiece as an initial slicing plane K ₀ Slicing from top to bottom. Each slice plane K _i The centroid of the geometric cross section of the upper molded workpiece is defined as R _i I=0, 1,2, … …, initialSlice plane K ₀ The initial centroid on the upper part is R ₀ 。

Step 2, in order to calculate and output the position and direction of the subsequent slice plane, each conformal slice layer P _i The nominal layer thickness is defined as T _i I=0, 1,2, … …, and the intersection angle of two adjacent slice plane normals is defined as the growth rotation angle α _i I=0, 1,2, … …, initial offset angle τ=1°.

Step 3, the later slice plane K _i+1 Is based on the slice plane K of the previous layer _i And nominal slice layer thickness T _i Determined by slicing plane K _i Centroid R of (2) _i Creating a radius T for the center of a circle _i The sphere surface and the mass center of the sphere surface are calculated as follows:

wherein Un is the coordinate point of the molded workpiece in the geometric section of the slicing plane Ki, un E { (X) _n ,Y _n ,Z _n ) I n= (1, 2, … …, L) }, L being the slice plane K of the shaped workpiece _i The number of coordinate points contained in the upper cross section.

Over centroid R _i As slice plane K _i Is defined as an initial intersection A ₀ The point A is moved along the sphere surface in four directions (X+, X-, Y+ and Y-) at offset angle τ ₀ Obtaining a point set A _m M=0, 1,2,3,4. Respectively connect A _m And centroid R _i Obtaining the corresponding normal A _m R _i Point A of crossing _m Creation and A _m R _i Vertical plane F _m M=0, 1,2,3,4. By this operation, five alternative slice planes F are obtained _m . Judging through a minimum section method to obtain a local optimal plane, wherein a section calculation formula is as follows:

wherein S is _m In alternative slice planes for forming workpiecesF _m Geometric cross-sectional area at m=0, 1,2,3,4; q (Q) _w In alternative slice plane F for forming workpieces _m At any point Q on the outer boundary of the geometric cross section ₁ Coordinate points obtained at intervals β clockwise for the start point, w=1, 2,3 … …, h,0<Beta is less than or equal to 1 mu m; h is the section plane F of the formed workpiece _m The number of the outer boundary coordinate points of the geometric section; q'. _D In alternative slice plane F for forming workpieces _m At any point Q 'on the boundary of the inner hole of the geometric section' ₁ D=1, 2,3 … …, H as coordinate points acquired by the starting point at the interval β clockwise; h is the section plane F of the formed workpiece _m The number of the inner hole boundary coordinate points of the geometric section; g is the section plane F of the formed workpiece _m The number of geometric cross-section holes, g=1, 2,3 … …, V; v is the section plane F of the formed workpiece _m The geometric cross-section of the inner hole is the largest.

The plane with the smallest geometric cross-sectional area of the formed workpiece is the local optimal slicing plane F _s (F _s ∈F _m ) The corresponding tangent point is the local optimal tangent point A _s (A _s ∈A _m )。

Step 4, updating the alternative slice plane to enable the initial intersection point A ₀ Equal to the local optimal tangent point A obtained by the previous round of searching _s Alternative slice plane F ₀ Equal to the local optimum slice plane F obtained by the previous round of search _s . After the update is completed, connect centroid R _i And A is a ₀ The point A is moved in four directions (X+, X-, Y+ and Y-) along the surface of the sphere at offset angle τ ₀ Obtain a new point A _m M=0, 1,2,3,4. Respectively connect A _m And centroid R _i Obtaining the normal A _m R _i Each point A _m Create a AND A _m R _i Vertical plane F _m . By this operation, five alternative slice planes F are obtained _m . Obtaining the cross-sectional area of the formed workpiece on the alternative slice plane by using a cross-sectional calculation formula (2), and obtaining a plane F with the minimum geometric cross-sectional area of the formed workpiece by a minimum cross-sectional method _s For a locally optimal plane, corresponding tangent point A _s Is a locally optimal tangent point. When the local optimum plane F _s ＝F ₀ I.e. the local optimum tangent point is A _s ＝A ₀ And (5) executing the step (5), otherwise, repeating the step (4).

Step 5, judging that when τ=0.001°, executing step 6; otherwise let τ=0.1τ, go to step 4.

Step 6, if alpha _i Less than or equal to 0.5 DEG, and the local optimum slice plane F is obtained at the moment _s Namely the next slice plane K _i+1 Obtaining a slice plane K _i And K is equal to _i+1 Conformal slice layer P of the formed workpiece therebetween _i Information, executing step 7; otherwise, let T _i ＝0.5T _i And executing the step 3-5.

And 7, repeating the steps 3-6 until the dynamic conformal slicing treatment of the three-dimensional model of the molded workpiece is completed by making i=i+1 and τ=1°.

S2, paving the powder on the high-temperature-resistant glass according to the Pi data and the position information of the conformal slice layer, wherein the actual layer thickness of the conformal slice layer after dynamic conformal slice treatment is in an uneven state, and adjusting the thickness of the powder layer by means of a flexible scraper to enable the thickness of the powder layer to meet the actual layer thickness setting of the conformal slice layer. And a plurality of heterogeneous powders can be paved on the surface of the high-temperature-resistant glass according to a set area, so that the additive manufacturing of the multi-dimensional heterogeneous material is realized.

S3, inputting the coordinate information obtained by the dynamic shape-following slice processing operation into a six-axis manipulator with a printing base at the tail end, moving the printing base to carry the formed workpiece to be positioned in the forming cabin, dynamically adjusting the position and the posture of the printing base according to the coordinate information, and enabling the formed and solidified shape-following slice layer P to be formed _i-1 The lower surface is closely attached to the next powder layer to be formed; for the first layer conformal slice layer P ₀ The lower surface of the printing base is provided with an adhesive, and after the pose of the printing base is adjusted, the lower surface of the printing base is tightly attached to the first powder layer.

S4, arranging a laser lens below the forming cabin, enabling a laser beam to melt or sinter a powder layer from below through high-temperature-resistant forming glass by means of the lens, carrying out laser selective additive manufacturing on the conformal slicing layer Pi in an inverted laser mode, and solidifying the formed first conformal slicing layer P ₀ Is adhered to the lower surface of the printing base.

S5, after the follow-up slice layer Pi is molded and solidified, the six-axis manipulator is controlled to lift the printing base and move the molded workpiece out of the molding cabin. And sucking and recovering residual powder on the high-temperature resistant glass in the forming cabin.

And S6, making i=i+1, repeating the steps S2-S5, sequentially preparing and solidifying the conformal slice layer from top to bottom until the preparation of the molded workpiece is completed, and removing the molded workpiece from the lower surface of the printing base.

For step S3, to achieve six-degree-of-freedom movement of the printing base, the printing base is mounted at the end of the six-axis manipulator, and the six-axis manipulator is arranged according to the slice plane centroid R _i The coordinates dynamically convert the spatial position and angle of the printing base. The centroid coordinates need to be converted into six-degree-of-freedom coordinates before being input into the manipulator control cabinet, and the converted ri= (X) _i ,Y _i ,Z _i ,U _i ,V _i ,W _i ) Wherein X is _i 、Y _i 、Z _i Respectively, relative to the centroid R of the absolute coordinate system _i Coordinates of U _i 、V _i 、W _i Respectively slice plane normal vectors K _i Included angles of x, y, z axes relative to an absolute coordinate system.

The actual layer thickness of the conformal slice layer after dynamic conformal slice treatment presents an uneven state, the strategy of changing laser power is adopted to control the molding quality and precision when preparing each slice layer, the energy density is limited on the basis, the laser power is adjusted according to the actual thickness of the powder layer, the thermal influence on the finished solidified layer is reduced, and the uniformity of internal tissues is improved. The specific control equation is as follows:

VED _i ＝Pτ _i /(vτ _i ×Hτ _i ×dτ _i ) (3)；

wherein, VED _i For the set laser action conformal slice layer P _i Energy density; pτ _i Is a conformal slice layer P _i Laser input power; vτ _i Is a conformal slice layer P _i Laser scanning speed; hτ _i Is a conformal slice layer P _i Powder thickness, dτ _i Is a conformal slice layer P _i The laser scans the pitch. The control strategy is to ensure the non-settingDisturbing other parameters and energy density VED _i On the premise of stability, the laser input power Pτ _i Concomitant slice layer actual layer thickness Hτ _i And changes.

Nominal slice layer thickness T _i Not more than 100 μm and not less than one-half of the average particle diameter of the powder. Different conformal slice layers may use different T' s _i 。

The gain effect of the invention:

(1) The invention provides a variable angle conformal laser selective area additive manufacturing method which comprises dynamic conformal slicing treatment, wherein the growth corner between slicing planes is adjusted by restraining the thickness of conformal sliced layers, and a three-dimensional model of a formed workpiece is discretized into a series of conformal sliced layers with unequal angles and thicknesses by taking the minimum cross-sectional area of the formed workpiece as an index. The multi-degree-of-freedom direction layered data processing of the workpiece can be realized through the method, the method is suitable for workpieces with various complex shapes, the preparation of cantilever structures and other structures which are difficult to ensure by adopting a plane slicing mode is realized, and the use of an additional supporting structure in the material adding process is avoided.

(2) According to the variable-angle conformal laser selective area additive manufacturing method provided by the invention, inverted laser is adopted, a strategy of layer-by-layer manufacturing from top to bottom is adopted, only a single powder layer is required to be paved on the surface of the high-temperature resistant glass in the forming cabin in the manufacturing process, the actual thickness of the powder layer is adjusted through the flexible scraper, and the paving of the non-uniform powder layer is facilitated, on one hand, the powder feeding device can be used for respectively paving heterogeneous powder on the surface of the high-temperature resistant glass according to a preset area, and the powder paving of various materials between layers is realized; realizing multi-dimensional heterogeneous material additive manufacturing; on the other hand, the quantity of various powder in the forming cabin is reduced, and the mixing probability of various powder is reduced. And the quality of the heterogeneous material additive component is improved.

(3) According to the variable-angle conformal laser selective area material-increasing manufacturing method provided by the invention, inverted laser is adopted, a strategy of layer-by-layer manufacturing from top to bottom is adopted, the upper end of a workpiece is fixed on the lower surface of a printing base, the pose of the printing base is dynamically adjusted according to coordinate information obtained by dynamic slicing treatment through a six-axis manipulator, the pose adjustment of multiple degrees of freedom of a complex workpiece can be realized, the limitation of a traditional molding powder cylinder on the size of the workpiece is avoided, and the preparation of large-size complex components is facilitated.

Drawings

FIG. 1 is a schematic diagram of dynamic random laser selective additive manufacturing process;

FIG. 2 is a schematic diagram of a dynamic conformal slice processing flow;

FIG. 3 is a schematic diagram of a dynamic conformal slice processing local optimum planar search;

FIG. 4 is a schematic view of dynamic conformal slicing process layering of a molded workpiece (print base station position);

FIG. 5 is a schematic view of dynamic shape-following slicing process layering of a shaped workpiece (refractory glass position);

FIG. 6 is a conformal slice layer P ₀ A linear scan path schematic;

reference numerals: 1-powder feeding device, 2-powder layer, 3-forming workpiece, 4-six-axis mechanical arm, 5-printing base station, 6-flexible scraper, 7-high temperature resistant glass, 8-lens and 9-laser.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in detail with reference to the accompanying drawings and specific embodiments.

Examples:

a certain sine-shaped pipe fitting has a height of 30 pi mm, and the center line expression of the pipe fitting after inverted placement is x=100000 sin (z/15000000) in units: the section of the material is annular with the outer diameter of 15mm and the wall thickness of 3 mm. The powder material is Ti6Al4V, and the variable angle conformal laser selective additive manufacturing processing is carried out by the following process steps:

s1, carrying out dynamic shape-following slicing treatment on the three-dimensional model of the S-shaped pipe, discretizing the slice plane of the three-dimensional model of the S-shaped pipe, and acquiring shape-following slice layers and related coordinate information from top to bottom. The slice plane is defined as K _i I=0, 1,2, … …, slice plane K _i And K is equal to _i+1 The conformal slice layer of the formed workpiece between is defined as P _i ，i＝0，1,2,……。

Slice layer P with first layer shape ₀ For example, a specific dynamic shape-following slice processing method is as follows：

1. The dynamic conformal slicing process sets the plane with the highest height direction of the S-shaped pipe piece as an initial slicing plane K ₀ The initial centroid is R ₀ Initial offset angle τ=1°.

2. Let the nominal layer thickness T of the conformal slice layer ₀ 100 μm, slice plane K ₀ And K is equal to ₁ The normal intersection angle between them is defined as the growth rotation angle alpha ₀ 。

3. In slice plane K ₀ Centroid R of (2) ₀ Creating a sphere surface with a radius of 100 mu m for a circle center, wherein a centroid calculation formula is as follows:

wherein Un is the coordinate point of the molded workpiece in the geometric section of the slicing plane Ki, un E { (X) _n ,Y _n ,Z _n ) I n= (1, 2, … …, L) }, L being the slice plane K of the shaped workpiece _i The number of coordinate points contained in the upper cross section. Obtaining a centroid R through a formula (1) ₀ The coordinates are (0, 0),

over centroid R ₀ (0, 0) as a slice plane K ₀ Is defined as an initial intersection A ₀ (0, 100) moving the point a along the sphere surface in four directions (x+, X-, y+ and Y-) at a bias angle τ=1° ₀ Obtain point A _m (m=0, 1,2,3, 4). Respectively connect A _m And centroid R _i Obtaining the corresponding normal A _m R _i Point A of crossing _m Creation and A _m R _i Vertical plane F _m (m=0, 1,2,3, 4). By this operation, five alternative slice planes F are obtained _m . Judging through a minimum section method to obtain a local optimal plane, wherein a section calculation formula is as follows:

wherein S is _m In alternative slice plane F for forming workpieces _m Geometric cross-sectional area of the upper part，m＝0,1,2,3,4；Q _w In alternative slice plane F for forming workpieces _m At any point Q on the outer boundary of the geometric cross section ₁ A coordinate point is obtained clockwise according to a distance beta as a starting point, w=1, 2,3 … … and h; h is the section plane F of the formed workpiece _m The number of the outer boundary coordinate points of the geometric section; q'. _D In alternative slice plane F for forming workpieces _m At any point Q 'on the boundary of the inner hole of the geometric section' ₁ D=1, 2,3 … …, H as coordinate points acquired by the starting point at the interval β clockwise; h is the section plane F of the formed workpiece _m The number of the inner hole boundary coordinate points of the geometric section; g is the section plane F of the formed workpiece _m The number of geometric cross-sectional holes, g=1, 2,3 … …, v; v=1.

The plane with the smallest geometric cross-sectional area of the formed workpiece is a local optimal plane F _s (F _s ∈F _m ) The corresponding tangent point is the local optimal tangent point A _s (A _s ∈A _m )。

4. Updating the alternative slice plane to enable the initial intersection point A ₀ Equal to the local optimal tangent point A obtained by the previous round of searching _s Alternative slice plane F ₀ Equal to the local optimum slice plane F obtained by the previous round of search _s . After the update is completed, connect centroid R _i And A is a ₀ The point A is moved in four directions (X+, X-, Y+ and Y-) along the surface of the sphere at offset angle τ ₀ Obtain a new point A _m M=0, 1,2,3,4. Respectively connect A _m And centroid R _i Obtaining the normal A _m R _i Each point A _m Create a AND A _m R _i Vertical plane F _m . By this operation, five alternative slice planes F are obtained _m . Obtaining the cross-sectional area of the formed workpiece on the alternative slice plane by using a cross-sectional calculation formula (2), and obtaining a plane F with the minimum geometric cross-sectional area of the formed workpiece by a minimum cross-sectional method _s For a locally optimal plane, corresponding tangent point A _s Is a locally optimal tangent point. When the local optimum plane F _s ＝F ₀ The local optimal tangent point is A _s ＝A ₀ And (5) executing the step (5), otherwise, repeating the step (4).

5, let τ=0.1τ, execute step 4 until τ=0.001 °, at which point the local optimum tangent point a is obtained ₀ (0.666651852337931,0, 99.997777851849160) and the corresponding local optimum slice plane F _s 。

6, slice plane K ₀ Is (0, 1), the locally optimal slice plane F _s Is (0.066665185233793,0,9.999777785184916), slice plane K ₀ And F is equal to _s Normal line angle of intersection growth angle alpha ₀ = 0.3819662021782669337 ° < 0.5 °, at which time the local optimum slice plane F _s Namely the next slice plane K ₁ Obtaining a slice plane K ₀ And K is equal to ₁ Conformal slice layer P of the formed workpiece therebetween ₀ Information, go to step 7 (if α ₀ More than or equal to 0.5 DEG, let T ₀ ＝0.5T ₀ And executing the step 3-5. )

And 7, repeating the steps 3-6 until the dynamic conformal slicing treatment of the three-dimensional model of the formed workpiece is completed by making i=i+1 and τ=1°.

S2, slicing the Ti6Al4V powder according to the conformal slice layer P _i The data and the position information are laid on the high temperature resistant glass, the actual conformal slice layer thickness after the dynamic conformal slice treatment presents an uneven state, and the thickness of the powder layer is adjusted by a flexible scraper to enable the powder layer thickness to meet the requirement of the conformal slice layer P _i Setting the actual layer thickness.

S3, inputting the coordinate information subjected to the dynamic shape-following slicing processing operation into a six-axis manipulator with a printing base at the tail end, moving the printing base to carry the formed workpiece in a forming cabin, and dynamically adjusting the position and the posture of the printing base according to the coordinate information obtained by the dynamic slicing processing to enable the formed and solidified shape-following slicing layer P _i-1 The lower surface is closely attached to the next layer of Ti6Al4V powder layer to be formed. (for the first layer conformal slice layer P ₀ The lower surface of the printing base is provided with an adhesive, and after the pose of the printing base is adjusted, the lower surface of the printing base is tightly attached to the first powder layer

S4, arranging a laser lens below the forming cabin, enabling a laser beam to melt or sinter the powder layer from below through high-temperature-resistant forming glass by means of the lens, and enabling the conformal slicing layer P to be shaped in an inverted laser mode _i And performing laser selective additive manufacturing. (first layer following slice layer P after curing and shaping) ₀ Is adhered to the lower surface of the printing base), and the molding quality and precision are controlled by adopting a strategy of changing laser power when preparing each slice layer.

Preparation of conformal slice layer P with Linear scanning strategy ₀ For example, by defining the energy density, the laser power is adjusted according to the actual thickness of the powder layer, and the specific control equation is as follows:

VED ₀ ＝Pτ ₀ /(vτ ₀ ×Hτ ₀ ×dτ ₀ ) (3)；

wherein, VED ₀ Conformal slice layer P for laser action ₀ Energy density, set VED ₀ ＝50W/mm ³ ；Pτ ₀ Is a conformal slice layer P ₀ Laser input power; vτ ₀ Is a conformal slice layer P ₀ Laser scanning speed, vτ ₀ ＝1000mm/s；Hτ ₀ Is a conformal slice layer P ₀ Powder thickness, dτ ₀ Is a conformal slice layer P ₀ Laser scan pitch dτ ₀ ＝50μm。

Due to T ₀ =100 μm, i.e. sheet plane K ₀ Distance R from the K centroid ₀ R ₁ =100 μm, slice plane K ₀ And K is equal to ₁ Growth rotation angle alpha ₀ 0.3819662021782669337 ° and the shaped workpiece section is annular with an outer diameter of 15mm and a wall thickness of 3 mm.

Then slice layer P follows ₀ The theoretical minimum powder thickness is:

conformal slice layer P ₀ The theoretical maximum powder thickness is:

as shown in fig. 6, a linear scanning strategy is applied to prepare a conformal slice layer P ₀ Self-conforming slice layer P ₀ Minimum powder thickness direction conformal slice layer P ₀ The scanning single channels are sequentially arranged at the maximum powder thickness, and the thickness and the power of each scanning single channel are sequentially as follows:

s5, conformal slice layer P _i After molding and curing, the six-axis manipulator is controlled to lift the printing base and move the molded workpiece out of the molding cabin.

Claims

1. The angle-variable shape-following laser selective area additive manufacturing method is characterized by comprising the following specific steps of:

s1, carrying out dynamic shape-following slicing treatment on a three-dimensional model of a formed workpiece, discretizing a slice plane of the three-dimensional model of the formed workpiece, and acquiring shape-following slice layers and related coordinate information from top to bottom; wherein the slice plane is defined as K _i I=0, 1,2, … … for slice plane K _i And K is equal to _i+1 The conformal slice layer of the formed workpiece between is defined as P _i ，i＝0,1,2,……；

Step S1 is subdivided into the following steps:

step 1, unlike the traditional Z-direction plane equidistant slicing, the dynamic shape-following slicing treatment sets the plane with the highest height direction of the formed workpiece as an initial slicing plane K ₀ Sequentially slicing from top to bottom to obtain slice planes K _i The centroid of the geometric cross section of the upper molded workpiece is defined as R _i I=0, 1,2, … …, initial slice plane K ₀ The initial centroid on the upper part is R ₀ ；

Step 2, in order to calculate and output the position and direction of the subsequent slice plane, each conformal slice layer P _i The nominal layer thickness is defined as T _i I=0, 1,2, … …, and the intersection angle of two adjacent slice plane normals is defined as the growth rotation angle α _i I=0, 1,2, … …, initialOffset angle τ=1°;

step 3, the later slice plane K _i+1 Is based on the slice plane K of the previous layer _i And nominal slice layer thickness T _i Determined by slicing plane K _i Centroid R of (2) _i Creating a radius T for the center of the sphere _i The sphere surface and the mass center of the sphere surface are calculated as follows:

wherein Un is the coordinate point of the molded workpiece in the geometric section of the slicing plane Ki, un E { (X) _n ,Y _n ,Z _n ) I n= (1, 2, … …, L) }, L being the slice plane K of the shaped workpiece _i The number of coordinate points contained in the upper section;

over centroid R _i As slice plane K _i Is defined as an initial intersection A ₀ The point A is moved along the sphere surface in four directions (X+, X-, Y+ and Y-) at offset angle τ ₀ Obtaining a point set A _m M=0, 1,2,3,4; respectively connect A _m And centroid R _i Obtaining the corresponding normal A _m R _i Point A of crossing _m Creation and A _m R _i Vertical plane F _m M=0, 1,2,3,4; by this operation, five alternative slice planes F are obtained _m The method comprises the steps of carrying out a first treatment on the surface of the Judging through a minimum section method to obtain a local optimal plane, wherein a section calculation formula is as follows:

wherein S is _m In alternative slice plane F for forming workpieces _m Geometric cross-sectional area at m=0, 1,2,3,4; q (Q) _w In alternative slice plane F for forming workpieces _m At any point Q on the outer boundary of the geometric cross section ₁ Coordinate points obtained at intervals β clockwise for the start point, w=1, 2,3 … …, h,0<Beta is less than or equal to 1 mu m; h is the section plane F of the formed workpiece _m Geometric section onThe number of out-of-plane boundary coordinate points; q'. _D In alternative slice plane F for forming workpieces _m At any point Q 'on the boundary of the inner hole of the geometric section' ₁ D=1, 2,3 … …, H as coordinate points acquired by the starting point at the interval β clockwise; h is the section plane F of the formed workpiece _m The number of the inner hole boundary coordinate points of the geometric section; g is the section plane F of the formed workpiece _m The number of geometric cross-section holes, g=1, 2,3 … …, V; v is the section plane F of the formed workpiece _m The largest number of inner holes of the geometric section;

the plane with the smallest geometric cross-sectional area of the formed workpiece is the local optimal slicing plane F _s (F _s ∈F _m ) The corresponding tangent point is the local optimal tangent point A _s (A _s ∈A _m )；

Step 4, updating the alternative slice plane to enable the initial intersection point A ₀ Equal to the local optimal tangent point A obtained by the previous round of searching _s Alternative slice plane F ₀ Equal to the local optimum slice plane F obtained by the previous round of search _s After the update is completed, connect centroid R _i And A is a ₀ The point A is moved in four directions (X+, X-, Y+ and Y-) along the surface of the sphere at offset angle τ ₀ Obtain a new point A _m M=0, 1,2,3,4; respectively connect A _m And centroid R _i Obtaining the normal A _m R _i Each point A _m Create a AND A _m R _i Vertical plane F _m Through this operation, five alternative slice planes F are obtained _m Obtaining the cross-sectional area of the formed workpiece on the alternative slice plane by using a cross-sectional calculation formula (2), and obtaining a plane F with the minimum geometric cross-sectional area of the formed workpiece by a minimum cross-sectional method _s For a locally optimal plane, corresponding tangent point A _s As a local optimum tangent point, the local optimum plane F _s ＝F ₀ I.e. the local optimum tangent point is A _s ＝A ₀ Executing the step 5, otherwise repeating the step 4;

step 5, judging that when τ=0.001°, executing step 6; otherwise, let τ=0.1τ, execute step 4;

step 6, if alpha _i Less than or equal to 0.5 DEG, thisLocally optimal slice plane F obtained at the time _s Namely the next slice plane K _i+1 Obtaining a slice plane K _i And K is equal to _i+1 Conformal slice layer P of the formed workpiece therebetween _i Information, executing step 7; otherwise, let T _i ＝0.5T _i Executing the step 3-5;

step 7, repeating the steps 3-6 until the dynamic conformal slicing treatment of the three-dimensional model of the formed workpiece is completed by making i=i+1 and τ=1°;

s2, paving powder on the high-temperature-resistant glass according to the Pi data and the position information of the conformal slice layer, wherein the actual layer thickness of the conformal slice layer after dynamic conformal slice treatment is in an uneven state, adjusting the thickness of the powder layer by means of a flexible scraper to enable the thickness of the powder layer to meet the actual layer thickness setting of the conformal slice layer, paving various heterogeneous powders on the surface of the high-temperature-resistant glass according to a set area, and realizing multi-dimensional heterogeneous material additive manufacturing;

s3, inputting the coordinate information obtained by the dynamic shape-following slice processing operation into a six-axis manipulator with a printing base at the tail end, moving the printing base to carry the formed workpiece to be positioned in the forming cabin, dynamically adjusting the position and the posture of the printing base according to the coordinate information, and enabling the formed and solidified shape-following slice layer P to be formed _i-1 The lower surface is closely attached to the next powder layer to be formed; for the first layer conformal slice layer P ₀ The lower surface of the printing base is provided with an adhesive, and after the pose of the printing base is adjusted, the lower surface of the printing base is tightly attached to the first powder layer;

s4, arranging a laser lens below the forming cabin, enabling a laser beam to melt or sinter a powder layer from below through high-temperature-resistant forming glass by means of the lens, carrying out laser selective additive manufacturing on the conformal slicing layer Pi in an inverted laser mode, and solidifying the formed first conformal slicing layer P ₀ Bonding to the lower surface of the printing base;

s5, after the follow-up slice layer Pi is molded and solidified, controlling a six-axis manipulator to lift the printing base station and move the molded workpiece out of the molding cabin, and sucking and recovering residual powder on high-temperature resistant glass in the molding cabin;

2. The method for manufacturing a variable angle conformal laser selective area additive material as claimed in claim 1, wherein for step S3, to achieve six degrees of freedom movement of the printing base, the printing base is mounted at the end of a six-axis manipulator, and the six-axis manipulator is based on a slice plane centroid R _i Coordinate dynamic conversion prints space position and angle of the base station, the barycenter coordinate needs to be converted into six degrees of freedom coordinate before inputting to the manipulator control cabinet, ri= (X) after conversion _i ,Y _i ,Z _i ,U _i ,V _i ,W _i ) Wherein X is _i 、Y _i 、Z _i Respectively, relative to the centroid R of the absolute coordinate system _i Coordinates of U _i 、V _i 、W _i Respectively slice plane normal vectors K _i Included angles of x, y, z axes relative to an absolute coordinate system.

3. The variable angle conformal laser selective area additive manufacturing method of claim 1, wherein the actual layer thickness of the conformal sliced layer after dynamic conformal slicing treatment presents a non-uniform state, the strategy of variable laser power is adopted to control the molding quality and precision when preparing each sliced layer, on the basis, the energy density is limited, the laser power is adjusted according to the actual thickness of the powder layer, the thermal influence on the finished solidified layer is reduced, the uniformity of internal tissues is improved, and the specific control equation is as follows:

VED _i ＝Pτ _i /(vτ _i ×Hτ _i ×dτ _i ) (3)；

wherein, VED _i For the set laser action conformal slice layer P _i Energy density; pτ _i Is a conformal slice layer P _i Laser input power; vτ _i Is a conformal slice layer P _i Laser scanning speed; hτ _i Is a conformal slice layer P _i Powder thickness, dτ _i Is a conformal slice layer P _i The laser scanning interval and the control strategy are that the energy density VED without disturbing other parameters is ensured _i StableOn the premise that the laser input power Pτ _i Concomitant slice layer actual layer thickness Hτ _i And changes.

4. A method of variable angle conformal laser selective area additive manufacturing as claimed in claim 1, wherein the conformal sliced layer has a nominal layer thickness T _i Not more than 100 μm and not less than one-half of the average particle diameter of the powder, different conformal slice layers can use unequal T _i 。