CN114559055B

CN114559055B - 3D printing method

Info

Publication number: CN114559055B
Application number: CN202210233756.5A
Authority: CN
Inventors: 韩向阳; 刘普祥; 魏盼
Original assignee: Shenzhen Huayang New Material Technology Co ltd
Current assignee: Shenzhen Huayang New Material Technology Co ltd
Priority date: 2022-03-10
Filing date: 2022-03-10
Publication date: 2023-08-11
Anticipated expiration: 2042-03-10
Also published as: CN114559055A

Abstract

The invention relates to the technical field of metal additive manufacturing, and in order to solve the technical problem of large stress existing in forming a part with a large area or a large sectional area change, the invention discloses a 3D printing method, which comprises the steps of defining laser beam scanning lines in a contour area, and scanning line by line in a serpentine line layout; defining laser scanning lines to be distributed in a shape of a Chinese character kou in a core area; scanning the solid outline area line by line once from left to right and from bottom to top at a fixed laser beam diameter, a preset power and a speed; increasing the diameter of the laser beam by a preset amplification factor, and randomly scanning two disjoint character shapes in the solid core area; and recovering the original diameter of the laser beam, scanning for a predetermined number of times along the outline of the entity, and performing powder spreading action after the scanning is finished. The partition, the scanning line shape and the scanning rotation mode are arranged, the scanning line length is reduced, the heat concentration is reduced through partition and sectional scanning, the stress concentration coefficient is reduced, and deformation and cracking are prevented.

Description

3D printing method

Technical Field

The invention relates to the technical field of metal additive manufacturing, in particular to a 3D printing method.

Background

The selective laser melting forming technology is characterized by rapid melting and solidification. The existing scanning method is extremely easy to generate high stress when forming large-area parts or products with large sectional area changes. Meanwhile, the scanning time is long, and the forming efficiency is low.

Disclosure of Invention

The invention aims to provide a 3D printing method to solve the technical problem of high stress in forming large-area parts or parts with larger sectional area changes.

In order to achieve the above purpose, the specific technical scheme of the 3D printing method of the present invention is as follows:

a 3D printing method, comprising the steps of:

step S1, importing a file of a target part into laser selective melting process slicing software;

s2, defining an A-A type section of the target part as a solid section, and defining a B-B type section of the target part as a hollow section;

defining a cross section boundary line as a solid outline, defining a solid outline area by horizontally extending a predetermined distance inwards along the solid outline, and defining the rest area of the solid outline area as a solid core area;

dividing the hollow section into an inner contour and an outer contour, defining the inner boundary line and the outer boundary line of the hollow section as an outer contour region, defining the inner contour region and the outer contour region as an inner contour region, and defining the hollow section residual region as a hollow core region;

step S3, defining laser beam scanning lines in a serpentine line layout in the solid outline area, the inner outline area and the outer outline area, and scanning line by line; defining laser scanning lines to be distributed in a shape of a Chinese character kou in the entity core area and the hollow core area;

s4, defining the space between snakelike lines as D, defining the length of the character pattern in the X direction as L, the length of the character pattern in the Y direction as H, the space between character pattern scanning lines in the X direction as w, the space between character pattern scanning lines in the Y direction as H, and defining the diameter of the laser beam as phi; wherein D is smaller than phi, L is larger than phi, H is larger than phi, w is smaller than phi, H is smaller than phi, H is larger than H, and L is larger than w;

step S5, if the current scanning object is a solid section, the laser beam comprises the following steps when scanning the current layer:

step S51, scanning the solid outline area line by line once from left to right and from bottom to top at a fixed laser beam diameter, a preset power and a preset speed;

step S52, increasing the diameter of the laser beam by a preset amplification factor, and randomly scanning two disjoint character shapes on the solid core area;

s53, recovering the original diameter of the laser beam, scanning for a preset number of times along the solid outline, and performing powder paving action by the printer after the scanning is finished;

step S54, scanning the next layer, and circularly executing the steps S51 to S53;

if the current scanning object is a hollow section, the laser beam comprises the following steps when scanning the current layer:

step S51', scanning the inner contour area and the outer contour area one by one line at the same time from left to right and from bottom to top at a fixed laser beam diameter, a preset power and a preset speed;

step S52', increasing the diameter of the laser beam by a preset amplification factor, and randomly scanning the hollow core area by two disjoint fonts;

step S53', recovering the original diameter of the laser beam, scanning for a preset number of times along the inner contour and the outer contour, and performing powder paving action by the printer after the scanning is finished;

step S54', scan the next layer, and loop through steps S51' to S53'.

The scanning line length is reduced by setting the subareas, the scanning line shape and the scanning rotation mode; through the regional and sectional scanning, the heat concentration is reduced, so that the stress concentration coefficient is reduced, and deformation and cracking are prevented.

Further, in step S5, the serpentine scan lines of adjacent layers are at an included angle α,180 ° > α > 1 °.

Further, in step S5, the zigzag scanning lines of the adjacent layers are rotated by an angle β in the clockwise direction, 180 ° > β > 91 °, and the zigzag scanning lines are moved by a distance δ in the X-direction and by a distance Ω in the Y-direction, wherein δ > 10×Φ, Ω > 10×Φ. By means of scanning rotation, overlapping of scanning lines on the upper side and the lower side is prevented, and metallurgical defects are avoided.

Further, in step S5, in the X direction, the distance between the glyphs is greater than 10 (l+w); in the Y direction, the distance between the glyphs is greater than 10 (h+h).

Further, in step S5, the ratio of the laser beam power to the scanning speed is maintained or increased before the laser beam diameter is changed.

Further, in step S5, after the original diameter of the laser beam is recovered, the power range of the laser beam is 35-300W, and the power range of the scanning speed of the laser beam is 50-900 mm/S.

Further, in step S5, the range of the predetermined amplification factor is 1.05 to 2.

Further, in step S5, the predetermined number of scans is in the range of 0 to 4.

The 3D printing method provided by the invention has the following advantages:

by arranging the subareas, different subareas are provided with different scanning line shapes, and the scanning lines between the adjacent layers are provided with rotation angles, so that the length of the scanning lines can be reduced, the scanning lines are shorter, the reaction speed is increased, the heat concentration is low, and the reduction of stress concentration is facilitated; the heat concentration is reduced through partition and sectional scanning, so that the stress concentration coefficient is reduced, and deformation and cracking are prevented; the arrangement of the scanning rotation mode can prevent the scanning lines on the upper side and the lower side from overlapping, and metallurgical defects are avoided. The scanning line adopting the form or the shape solves the problems of long scanning time and low forming efficiency.

Drawings

FIG. 1 is a schematic illustration of a hollow box part provided by the present invention;

FIG. 2 is a cross-sectional view of parts A-A and B-B provided by the present invention;

FIG. 3 is a cross-sectional view of a laser scanning pattern A-A provided by the present invention;

FIG. 4 is a partial enlarged view for the position A in FIG. 3;

FIG. 5 is a cross-sectional view of a laser scanning format B-B provided by the present invention;

FIG. 6 is a partial enlarged view for B in FIG. 5;

fig. 7 is a schematic view of scanning of a non-contour area according to the present invention.

In the figure: 11. a physical outline; 12. a physical core area; 13. a solid outline region; 211. an outer contour; 212. an inner profile; 22. a hollow core region; 231. an outer contour region; 232. inner contour area.

Detailed Description

The present invention will be described in further detail with reference to the drawings and examples, in order to make the objects, technical solutions and advantages of the present invention more apparent. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention.

Aiming at the problems of large stress and low forming efficiency of a large-area part or a product with larger sectional area change formed by selective laser melting, the invention provides a 3D printing method.

Referring to FIG. 1, a pre-printed part is defined, typically having either concave or convex portions, and the present invention is illustrated as a hollow box representing the basic structure of the part.

According to the principle of selective laser melting forming, the part is formed in a layer-by-layer stacking mode. The internal hollow box body is used as a file of a target part to be imported into a laser selective melting process slicing software, and the layering thickness of each part is defined as d.

Referring to fig. 2, the sectional area of the case body is abrupt in the height direction, and the sectional shapes of the case body at different positions are greatly different. And slicing the box body parts by slicing software. A profile slice with a layer thickness d is formed. The sectional shape is also different depending on the height.

The A-A type section is defined as a solid section, and the B-B type section is defined as a hollow section. Because the solid section and the hollow section are different in area, the product stress is effectively reduced, and the forming effect is improved. During subsequent scanning, different scanning strategies are defined.

Referring to fig. 3 and 4, the cross-sectional area thereof is divided according to the solid cross-sectional area. The solid cross-section boundary line is defined as a solid outline 11. In the X direction, a region having a dimension T from the solid outline 11 and a dimension T from the solid outline in the Y direction is defined as a solid outline region 13. The areas other than the solid outline area 13 are defined as solid core areas 12. The values of the dimensions T and T may be the same or different, and may be defined as the distance along the normal vector of the physical outline 11. Meanwhile, the numerical values of T and T are smaller than half of the side lengths of the solid section in the horizontal and vertical directions.

For the solid profile region 13, the laser scan lines are in a serpentine arrangement, in a progressive scan. For the core region, the laser scan lines are in the form of a letter, a return letter, or multiple enclosures.

The distance between the serpentine scanning lines is defined as D, and the length of the X direction of the orographic scanning lines is defined as L. The length of the Y direction is H, the X-direction distance of the scanning lines is w, and the Y-direction distance is H. The laser beam diameter is defined as Φ. Wherein D is less than phi, L is more than phi, H is more than phi, w is less than phi, H is less than phi, H is more than H, and L is more than w.

The laser beam first maintains the laser beam diameter phi unchanged while scanning the current layer. The outer contour area is scanned line by line from left to right and from bottom to top along a serpentine scanning line at a specific laser power P at a laser scanning speed V only once. Wherein the scanning power P of the laser beam is 50-300W; the scanning speed V of the laser beam is 50-1000 mm/s.

The diameter phi of the laser beam is then enlarged, and the diameter enlargement factor K is preferably in the range of 1.05 to 2. The laser beam begins to scan the core region along the zig-zag scan line. When scanning, the laser beam completes the complete scanning of a single character-shaped scanning line in random sequence. The next glyph scan line is then randomly scanned. Two character-shape scanning lines of continuous scanning are ensured, and the X-direction line segments are not directly connected. The distance between each other is more than 10 (L+w); the Y-direction line segments are not directly connected, and the distance between the Y-direction line segments is larger than 10 (H+h). Only once.

After the laser beam diameter becomes larger, the laser power increases and the laser scanning speed remains unchanged or decreases appropriately. Or the laser power is unchanged, and the laser scanning speed is reduced. The laser power P is 60-300W; the laser scanning speed V is 40-1000 mm/s. In any case, the ratio of the laser power P to the laser scanning speed V is ensured to be unchanged or to be increased appropriately compared with the laser beam diameter before being changed.

Finally, the laser beam diameter is adjusted back to the original size Φ. Scanning along the solid outline 11 is started. After the laser beam diameter is adjusted, the laser power is reduced, and the laser scanning speed is maintained unchanged or is increased appropriately. The laser power P is 35-300W, and the laser scanning speed V is 50-900 mm/s.

The number of profile scans is N, which can be defined as 0, 1, 2, 3, 4.

After the current layer is scanned, the 3D printer finishes laying powder, and the laser beam starts to scan the next layer.

When scanning the next layer, the laser beam first begins to scan the solid profile region 13 along a serpentine scan line, as previously described. The laser power and scanning speed are the same as the previous layer. However, the direction of the serpentine scanning line changes at an angle alpha, 180 degrees alpha > 1 degrees, with the scanning line of the previous layer, and each subsequent layer scans the solid outline area 13 in this way.

After the solid outline region 13 is scanned, the laser beam begins to scan the solid core region 12 along the zig-zag scan line in a manner consistent with that described above. But the direction of the zig-zag scan line is also changed. In the clockwise direction, the n+1th layer scan line segment is rotated by a certain angle beta, 180 degrees > beta > 91 degrees compared with the N layer. At the same time, the square scanning line moves along the X direction by a certain distance delta and along the Y direction by a certain distance omega. And delta > 10 x phi; omega > 10 x phi. Ensuring that the scan lines of the two connected layers do not overlap. Each subsequent layer scans the core area in this manner.

And (5) circularly and reciprocally, and sequentially completing the scanning of the solid section.

Referring to fig. 5 and 6, for a hollow section, its sectional area is divided according to its sectional area. The inner and outer boundary lines of the defined section are respectively an outer contour 211 and an inner contour 212. A region having a dimension T1 from the outer contour 211 in the X direction and a dimension T1 from the outer contour 211 in the Y direction is defined as an outer contour region 231. In the X-direction, a region having a dimension T3 from inner contour 212 and a dimension T3 from inner contour 212 in the Y-direction is defined as inner contour region 232.

The hollow section is defined as a hollow core region 22 except for the inner and outer contour regions 231. The X-direction dimension of the core region is T2, and the Y-direction dimension is T2.

The values of the dimensions T1 and T3 and T1 and T3 may be the same or different, and may be defined as the distance along the normal vector of the contour. Simultaneously, the numerical values of T1 and T3 and T1 and T3 are smaller than half of the side lengths of the hollow section in the horizontal and vertical directions.

For the inner contour area and the outer contour area, the laser scanning lines are in a serpentine layout and adopt a progressive scanning mode. For the core region, the laser scan lines are in the form of a letter, a return letter, or multiple enclosures. The scan lines are equally spaced apart as shown in fig. 4 (only the pictographic form is shown for ease of illustration).

An inner contoured region 232 and an outer contoured region 231, the laser beam scan lines are scanned line by line in a serpentine arrangement. The difference is that the inner profile area 232 and the outer profile area 231 do not need to be sequenced. And the serpentine scan directions of the inner contour region 232 and the outer contour region 231 may be the same or different. If different, the two parts are in the same cross section. A certain included angle is formed between the two components, and the included angle is 0-180 degrees.

For the hollow core region 22, the laser scan lines are laid out in a zig-zag, or multiple surrounds.

The outer contour 211 and the inner contour 212 of the hollow section correspond to the way the solid contours are scanned as described above.

And after the scanning of the current layer is completed, the scanning is performed in a manner of scanning the solid section until the scanning of the hollow section area is completed.

Further, referring to fig. 7, in order to improve the appearance quality of the product, when the vector dimension in the height direction of the box body or along the normal vector of the contour line is smaller than M. At this time, the cross section in the height direction is only the core region and the contour line. The core area is scanned in a serpentine mode, the specific scanning mode is consistent with the previous scanning mode, and the printing work of the box part is completed in a circulating and reciprocating mode.

In summary, a 3D printing method can be obtained, which includes the following steps:

step S1, importing a file of a target part into laser selective melting process professional software;

for the solid cross-section dividing region, a cross-section boundary line is defined as a solid outline 11, a predetermined distance extending horizontally inward along the solid outline 11 is defined as a solid outline region 13, and the remaining region of the solid outline region (13) is defined as a solid core region 12;

for the hollow cross-section dividing region, the inner and outer boundary lines defining the hollow cross-section are respectively an inner contour 212 and an outer contour 211, a predetermined distance extending horizontally inward along the outer contour 211 is defined as an outer contour region 231, a predetermined distance extending horizontally outward along the inner contour 212 is defined as an inner contour region 232, and the hollow cross-section remaining region is defined as a hollow core region 22;

step S3, defining laser beam scanning lines in a serpentine line layout in the solid outline region 13, the inner outline region 232) and the outer outline region 231, and scanning line by line; defining laser scan lines in a zig-zag arrangement in the solid core region 12 and the hollow core region 22;

step S51, scanning the solid outline region 13 line by line once from left to right and from bottom to top at a fixed laser beam diameter, a predetermined power and a predetermined speed;

step S52, increasing the diameter of the laser beam by a preset amplification factor, and randomly scanning two disjoint character shapes on the solid core area 12;

step S53, recovering the original diameter of the laser beam, scanning for a preset number of times along the solid outline 11, and performing powder spreading action by the printer after the scanning is finished;

step S51' of scanning the inner contour area 232 and the outer contour area 231 simultaneously one time row by row from left to right, from bottom to top, with a fixed laser beam diameter, a predetermined power and a speed;

step S52', increasing the diameter of the laser beam by a preset amplification factor, and randomly scanning the hollow core area 22 by two disjoint glyphs;

step S53', recovering the original diameter of the laser beam, scanning along the inner contour 212 and the outer contour 211 for a preset number of times at the same time, and performing powder spreading action by the printer after the scanning is finished;

step S54', scan the next layer, and loop through steps S51' to S53'.

According to the 3D printing method provided by the invention, the subareas are arranged, different scanning line shapes are arranged in different subareas, and the scanning lines between adjacent layers are provided with the rotation angles, so that the length of the scanning lines can be reduced, the scanning lines are shorter, the reaction speed is increased, the heat concentration degree is low, and the stress concentration is reduced; the heat concentration is reduced through partition and sectional scanning, so that the stress concentration coefficient is reduced, and deformation and cracking are prevented; the arrangement of the scanning rotation mode can prevent the scanning lines on the upper side and the lower side from overlapping, and metallurgical defects are avoided. The scanning line adopting the form or the shape solves the problems of long scanning time and low forming efficiency.

The foregoing description of the preferred embodiments of the invention is not intended to be limiting, but rather is intended to cover all modifications, equivalents, and alternatives falling within the spirit and principles of the invention.

Claims

1. A 3D printing method, comprising the steps of:

defining a cross-section boundary line as a solid outline (11), defining a solid outline region (13) extending horizontally inward a predetermined distance along the solid outline (11), and defining the remaining region of the solid outline region (13) as a solid core region (12);

for the hollow section dividing region, an inner boundary line and an outer boundary line which define the hollow section are respectively an inner contour (212) and an outer contour (211), a predetermined distance is defined as an outer contour region (231) which extends horizontally inwards along the outer contour (211), a predetermined distance is defined as an inner contour region (232) which extends horizontally outwards along the inner contour (212), and a hollow section remaining region is defined as a hollow core region (22);

step S3, defining laser beam scanning lines in a serpentine layout in the solid outline area (13), the inner outline area (232) and the outer outline area (231), and scanning line by line; defining laser scan lines in a mouth-shaped layout in a solid core region (12) and a hollow core region (22);

step S51, scanning the solid outline area (13) line by line once from left to right and from bottom to top at a fixed laser beam diameter, a preset power and a preset speed;

step S52, increasing the diameter of the laser beam by a preset amplification factor, and randomly scanning two disjoint character shapes on the solid core area (12);

s53, recovering the original diameter of the laser beam, scanning for a predetermined number of times along the solid outline (11), and performing powder spreading action by the printer after the scanning is finished;

step S51', scanning the inner contour area (232) and the outer contour area (231) one time from left to right, from bottom to top and row by row at the same time with a fixed laser beam diameter, a preset power and a preset speed;

step S52', increasing the diameter of the laser beam by a preset amplification factor, and randomly scanning the hollow core area (22) for two disjoint characters;

step S53', recovering the original diameter of the laser beam, scanning for a preset number of times along the inner contour (212) and the outer contour (211) simultaneously, and performing powder spreading action by the printer after the scanning is finished;

step S54', scan the next layer, and loop through steps S51' to S53'.

2. A 3D printing method according to claim 1, characterized in that in step S5 the serpentine scan lines of adjacent layers form an angle α,180 ° > α > 90 °.

3. A 3D printing method according to claim 2, wherein in step S5, the zigzagged scan lines of adjacent layers are rotated by an angle β,180 ° > β > 91 °, while the zigzagged scan lines are moved by a distance δ, δ > 10X Φ, Ω > 10X Φ, in the X direction.

4. A 3D printing method according to claim 3, wherein in step S5, the distance between the glyphs in the X-direction is greater than 10 (l+w); in the Y direction, the distance between the glyphs is greater than 10 (h+h).

5. A 3D printing method according to claim 4, wherein in step S5 the ratio of the laser beam power to the scanning speed is maintained or increased before the laser beam diameter is changed.

6. The 3D printing method as defined in claim 5, wherein in step S5, after recovering the original diameter of the laser beam, the power range of the laser beam is 35-300W and the power range of the scanning speed of the laser beam is 50-900 mm/S.

7. The 3D printing method according to claim 5, wherein in step S5, the predetermined magnification factor ranges from 1.05 to 2.

8. The 3D printing method according to claim 7, wherein in step S5, the predetermined number of scans is in a range of 0 to 4.