Laser scanning path planning method and additive manufacturing method

Abstract

The present invention relates to the field of additive manufacturing technology, and discloses a laser scanning path planning method and an additive manufacturing method, which include the following steps: establishing a three-dimensional model of a part to be formed, slicing the three-dimensional model to obtain a plurality of slice layers; obtaining data of the original contour line of any of the slice layers, offsetting the original contour line of the slice layer inward in sequence, finally obtaining a plurality of contour lines, generating a contour line group corresponding to the slice layer, and numbering each contour line of the contour line group from the outside to the inside as i1, i2...in, where n≥2; connecting each contour line of the contour line group from the outside to the inside in sequence to form a spiral laser scanning path corresponding to each slice layer. The present invention is more in line with the original contour shape of the slice layer, ensuring that the laser head continuously travels a long distance at the rated speed, reducing the number of light interruptions and frequent speed switching, while improving the scanning flatness and the part forming quality.

Description

Technical Field

[0001] The present invention relates to the technical field of 3D printing, and in particular to a laser scanning path planning method and an additive manufacturing method. Background Art

[0002] Laser Deposition Melting (LDM) technology, which features powder feeding, is an organic combination of rapid prototyping technology and laser cladding technology. It uses metal powder as raw material and high-energy laser beam as heat source. According to the scanning path planned by the layered slicing information of the CAD model of the formed part, the fed metal powder is melted layer by layer, quickly solidified, and deposited layer by layer, thereby realizing the direct manufacturing of the entire metal part.

[0003] In the deposition process of metal parts, the laser scanning path directly affects the part structure. At present, the more mature filling path planning schemes in the industry mainly include parallel lines, arc lines, etc. On parts with arc features, the above scanning schemes have disadvantages such as more broken light, more empty paths, and less smooth surface of parts. Summary of the invention

[0004] The object of the present invention is to provide a laser scanning path planning method and an additive manufacturing method, which are used to fit the original contour shape of the part slice as closely as possible and improve the smoothness quality of the part surface.

[0005] In order to achieve the above object, the present invention provides the following technical solutions:

[0006] A laser scanning path planning method comprises the following steps:

[0007] Establishing a three-dimensional model of the part to be formed, and slicing the three-dimensional model to obtain a plurality of slice layers;

[0008] Acquire the data of the original contour line of any of the slice layers, perform inward offset processing on the original contour line of the slice layer in turn, finally obtain a plurality of contour lines, generate a contour line group corresponding to the slice layer, and number each contour line of the contour line group from the outside to the inside as i1, i2....in, where n≥2;

[0009] Each contour line of the contour line group is sequentially connected from the outside to the inside to form a spiral laser scanning path corresponding to each slice layer.

[0010] Compared with the prior art, the present invention obtains a contour line group by processing the original contour line offset, and forms a complete spiral laser scanning path by sequentially and continuously processing all contour lines, which can fully cover the slice layer, ensure that the laser head travels a longer distance at the rated speed, reduce the number of light interruptions and frequent speed switching, facilitate heat dissipation, avoid thermal stress concentration, and the walking path largely fits the original contour shape of the part slice layer, thereby greatly improving the smoothness quality of the part surface;

[0011] The "step effect" and oxidation phenomenon caused by multiple scanning of the original contour by the traditional scanning path can be avoided, especially for metal materials with poor liquid fluidity and poor wettability, as well as parts with complex, curved, thin-walled structures. The contour lines are scanned multiple times, which has the disadvantages of more broken light, more empty paths, and less smooth surface of parts. The technical solution of the present invention can effectively improve the surface quality of the product, simplify the surface treatment process, and improve production efficiency and product qualification rate.

[0012] In one implementation, the step of sequentially connecting each contour line of the contour line group from outside to inside to form a spiral laser scanning path corresponding to each slice layer specifically includes:

[0013] Take any point on the contour line i1 as the entry point, and make a tangent line of the contour line i1 from the entry point, and the angle between the tangent line and the preset straight line is σ;

[0014] A tangent is drawn for each of the contour lines obtained by the offset, all the tangents are parallel to each other, and all the tangents are numbered L1, L2, L3, ..., Ln from the outside to the inside;

[0015] Intersect the tangent line Lm+1 with the contour line im, and obtain the positions of the two intersection points of the tangent line Lm+1 and the contour line im, where 1≤m≤n;

[0016] Taking the entry point of the contour line i1 as the starting point, laser scanning is performed along a first direction, the first direction being a clockwise or counterclockwise direction, taking the second intersection point where the contour line i1 and the tangent line L2 intersect in the first direction as the inflection point, and entering the contour line i2 along the tangent line L2;

[0017] Scan along the first direction on the contour line im+1, and enter the contour line im+2 with the second intersection point where the contour line im+1 and the tangent line Lm+2 in the first direction as the turning point, and complete the laser scanning from the contour line i1 to the contour line in sequence, and connect the contour line group in series into a U-shaped spiral line.

[0018] When the above technical solution is adopted, the spiral scanning path formed by the above scanning method is more closely aligned with the original contour shape of the slice layer, ensuring that the laser head can travel continuously for a long distance at the rated speed, reducing the number of light interruptions and frequent speed switching, and can effectively eliminate the accumulation of thermal stress in the scanning layer, while improving the scanning flatness and the quality of part molding; avoiding the traditional scanning path causing relatively sharp corners at the edge of the part. During the actual printing process, the laser head travel speed changes frequently, and the acceleration and deceleration process at the sharp corners will cause the actual travel route to be longer, and the metal powder will be stacked more, resulting in powder waste and rough part surface.

[0019] In one implementation, the data of the original contour line of any of the slice layers is obtained, and the original contour line of the slice layer is offset inward in sequence to finally obtain a plurality of contour lines, a contour line group corresponding to the slice layer is generated, and each contour line of the contour line group is numbered i1, i2....in from the outside to the inside; specifically: the original contour line of the slice layer is offset inward in sequence at equal distances to obtain a plurality of contour lines, and the offset distance of the contour line is d.

[0020] When the above technical solution is adopted, the distance between each two adjacent contour lines in and contour lines in+1 is d, which is conducive to the planning of the laser scanning path, making the scanning more uniform and improving the scanning quality.

[0021] In one implementation, a tangent is made to each of the contour lines obtained by the offset, and all the tangents are parallel to each other;

[0022] Specifically, a tangent is made for each of the offset contour lines, all of the tangents are parallel to each other, and the distance between every two adjacent tangents is D, and D is calculated by the inclination angle σ of the tangent L1 and the offset distance d.

[0023] When the above technical solution is adopted, based on the tangent L1 on the original contour line i1, the tangent L2 on the contour line i2 can be made according to the distance D between two adjacent tangents, and all tangents such as tangents L3, L4, L5 can be made by analogy.

[0024] In one implementation, the distance D between two adjacent tangent lines is cosσ*(sinσ / cosσ*d+d).

[0025] In one implementation, the tangent line Lm+1 is intersected with the contour line im to obtain the positions of the two intersection points of the tangent line Lm+1 and the contour line im; specifically:

[0026] According to the inclination angle σ of the tangent line L1, the distance D between two adjacent tangent lines and the position of the entry point, starting from the contour line i2, make tangents for each contour line from the outside to the inside, find the intersection point of each tangent line Lm+1 with the contour line im, and record the position of the intersection point.

[0027] An additive manufacturing method, using the laser scanning path planning method described in the first aspect to plan a scanning path;

[0028] By adopting the coaxial powder feeding method, laser scanning and deposition are performed on each slice layer of the part to be formed according to the planned scanning path, and the part to be formed is formed layer by layer.

[0029] When the above technical solution is adopted, the laser scanning path planning method described in the first aspect is applied to the coaxial powder feeding additive manufacturing method, which can increase the application scope of the coaxial powder feeding technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The drawings described herein are used to provide further understanding of the present invention and constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0031] Figure 1 This is a schematic diagram of an I-shaped laser scanning route in the prior art;

[0032] Figure 2 A schematic diagram of a contour line group for a specific workpiece slice layer processed according to an embodiment of the present invention;

[0033] Figure 3 A schematic diagram of a tangent line with an incision angle σ for an incision point on an original contour line according to an embodiment of the present invention;

[0034] Figure 4 A schematic diagram of the distance between two adjacent tangent lines according to an embodiment of the present invention;

[0035] Figure 5 A schematic diagram of making tangent lines for each contour line according to an embodiment of the present invention;

[0036] Figure 6 It is a schematic diagram of the intersection of the tangent line Lm+1 and the contour line im according to an embodiment of the present invention;

[0037] Figure 7 A laser scanning route map according to an embodiment of the present invention;

[0038] Figure 8 Schematic diagram of the spiral scanning obtained in the embodiment of the present invention. DETAILED DESCRIPTION

[0039] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0040] In the description of the present invention, it is necessary to understand that the terms "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship are based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0041] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0042] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0043] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0044] like Figure 1As shown, the I-shaped scanning path used in the traditional process will produce relatively sharp corners at the edge of the part. In the actual printing process, the speed of the laser head changes frequently. The acceleration or deceleration process at the sharp corners will cause the actual travel route to be longer and the metal powder to be stacked more, resulting in powder waste and rough part surface.

[0045] To solve the above problems, an embodiment of the present invention discloses a laser scanning path planning method, comprising the following steps:

[0046] S1: Establish a three-dimensional model of the part to be formed, slice the three-dimensional model, and obtain a number of slice layers;

[0047] S2: Get the original contour line data of any slice layer, offset the original contour line of this slice layer inwards in sequence, finally get several contour lines, generate a contour line group corresponding to this slice layer, and number each contour line of the contour line group from outside to inside as i1, i2....in, where n≥2;

[0048] S3: Connect each contour line of the contour line group from outside to inside in sequence to form a spiral laser scanning path corresponding to each slice layer.

[0049] Compared with the prior art, the present invention obtains a contour line group by offsetting the original contour line, which can fully cover the slice layer; all contour lines are sequentially and continuously formed into a complete spiral laser scanning path, ensuring that the laser head travels a longer distance at the rated speed, reducing the number of light interruptions and frequent speed switching, which is beneficial to heat dissipation and avoiding thermal stress concentration, and the travel path largely fits the original contour shape of the part slice layer, greatly improving the smoothness quality of the part surface;

[0050] The "step effect" and oxidation phenomenon caused by multiple scanning of the edge contour of the slice layer by the traditional scanning path can be avoided, especially for metal materials with poor liquid fluidity and poor wettability, and parts with complex, curved, thin-walled structures. The contour lines are scanned multiple times, which has the disadvantages of more broken light, more empty paths, and less smooth surface of parts. The technical solution of the present invention can effectively improve the surface quality of the product, simplify the surface treatment process, and improve production efficiency and product qualification rate.

[0051] Specifically, the above step S3 includes:

[0052] S300: taking any point on the contour line i1 as an entry point, and drawing a tangent line of the contour line i1 from the entry point, wherein the angle between the tangent line and a preset straight line is σ, wherein the preset straight line may be an X-axis line in the established rectangular coordinate system, or a straight line determined in other directions;

[0053] S301: Draw tangents for each contour line obtained by offset, all tangents are parallel to each other, and all tangents are numbered L1, L2, L3, ..., Ln from outside to inside;

[0054] S302: intersecting the tangent line Lm+1 with the contour line im, obtaining positions of two intersection points of the tangent line Lm+1 and the contour line im, where 1≤m≤n;

[0055] S303: taking the entry point of the contour line i1 as the starting point, performing laser scanning along a first direction, the first direction being a clockwise or counterclockwise direction, taking the second intersection point where the contour line i1 intersects with the tangent line L2 in the first direction as the turning point, and entering the contour line i2 along the tangent line L2;

[0056] S303: Scan along the first direction on the contour line im+1, and enter the contour line im+2 with the second intersection point of the contour line im+1 and the tangent line Lm+2 in the first direction as the turning point, and complete the laser scanning from the contour line i1 to the contour line in sequence, and connect the contour line groups into a U-shaped spiral line.

[0057] In this case, the spiral scanning path formed by the above scanning method is more in line with the original contour shape of the slice layer, ensuring that the laser head can travel continuously for a long distance at the rated speed, reducing the number of light interruptions and frequent speed switching, and can effectively eliminate the thermal stress accumulation in the scanning layer, while improving the scanning flatness and the part molding quality; avoiding the traditional scanning path causing relatively sharp corners at the edge of the part. In the actual printing process, the laser head travel speed changes frequently, and the acceleration and deceleration process at the sharp corners will cause the actual travel route to be longer, and the metal powder will be stacked more, resulting in powder waste and rough part surface.

[0058] As preferably, Figure 2 As shown, step S2 is specifically: the original contour line of the slice layer is offset inward in sequence with equal distances to obtain a plurality of contour lines, and the offset distance of the contour line is d. In this case, the distance between each two adjacent contour lines in and contour line in+1 is d, which is conducive to the planning of the laser scanning path, making the scanning more uniform and improving the scanning quality.

[0059] According to actual operation requirements, the entry point of the original contour line is preferably selected from the upper left, lower left, lower right, and upper right of the figure. Taking the upper left as an example, Figure 3 A brief description:

[0060] Point p0 is the entry point of the tangent line Lm at the upper left corner of the contour line im. The straight line p1p0 is named as the tangent line Lm, and the straight line p0p2 is the preset straight line. 1≤m≤n, and ∠p1p0p2 is the set entry angle σ. According to the entry angle σ and the offset distance d, the distance D between two adjacent tangent lines is calculated as cosσ*(sinσ / cosσ*d+d). Figure 4 The length of the midline segment b0b1 is the distance D between the tangent lines l1 and l2.

[0061] In some implementations, such as Figure 5 As shown, step S301 is specifically as follows: tangents are drawn for each contour line obtained by offset, all tangents are parallel to each other, and the distance between each two adjacent tangents is D, which is calculated by the inclination angle σ of the tangent L1 and the offset distance d. In this case, based on the tangent L1 on the original contour line i1, the tangent L2 on the contour line i2 can be drawn according to the distance D between the two adjacent tangents, and so on, all tangents such as tangents L3, L4, L5, etc. can be drawn.

[0062] Specifically, the distance D between two adjacent tangent lines = cosσ*(sinσ / cosσ*d+d).

[0063] In some implementations, such as Figure 6 As shown, step S302 is specifically as follows: starting from contour line i2, according to the inclination angle σ of tangent line L1, the distance D between two adjacent tangent lines and the position of the entry point, tangent lines are made for each contour line from the outside to the inside, the intersection point of each tangent line Lm+1 and contour line im is obtained, and the position of the intersection point is recorded.

[0064] The present invention also discloses an additive manufacturing method, which uses the laser scanning path planning method described above to plan the scanning path; adopts a coaxial powder feeding method to perform laser scanning deposition on each slice layer of the part to be formed according to the planned scanning path, and forms the part to be formed layer by layer. In this case, applying the laser scanning path planning method described in the present invention to the coaxial powder feeding additive manufacturing method can increase the application scope of the coaxial powder feeding technology.

[0065] The present invention is applicable to parts with regular shapes, as well as complex, curved, thin-walled and other structures, and can effectively improve the surface quality of products.

[0066] The present invention is briefly described below by taking a cylindrical part as an example.

[0067] S1: import a cylindrical 3D model with a radius of 100 mm and a height of 10 mm, slice the 3D model, and obtain several slice layers;

[0068] S2: Get the original contour line data of any slice layer, and perform equal distance offset processing on the original contour line of this slice layer inwards in sequence. The offset distance d of the contour line is 3mm. Finally, several contour lines are obtained, and a contour line group corresponding to this slice layer is generated. Each contour line of the contour line group is numbered i1, i2....in from the outside to the inside, where n≥2;

[0069] S3: Take any point on the contour line i1 as the entry point, and draw a tangent line from the entry point to the contour line i1. The angle σ between the tangent line and the horizontal line is 30°;

[0070] S4: Draw tangents for each contour line obtained by offset, all tangents are parallel to each other, and all tangents are numbered L1, L2, L3...Ln from the outside to the inside; the distance between each two adjacent tangents is D, where D is calculated by the inclination angle σ of the tangent L1 and the offset distance d, D = cosσ*(sinσ / cosσ*d+d);

[0071] S5: According to the inclination angle σ of the tangent line L1, the distance D between two adjacent tangent lines and the position of the entry point, starting from the contour line i2, a tangent line is drawn to each contour line from the outside to the inside, and the intersection point of the tangent line Lm+1 and the contour line im is obtained, and the position of the intersection point is recorded, where 1≤m≤n;

[0072] S6: Taking the cut-in point of the contour line i1 as the starting point, laser scanning is performed along the first direction, where the first direction is the clockwise direction. Figure 7 As shown, the second intersection point where the contour line i1 and the tangent line L2 in the first direction intersect is taken as the turning point, and the contour line i2 is entered along the tangent line L2;

[0073] S7: Scan along the first direction on the contour line im+1, take the second intersection point of the contour line im+1 and the tangent line Lm+2 in the first direction as the turning point to enter the contour line im+2, complete the laser scanning from the contour line i1 to the contour line in sequence, and connect the contour line groups in series Figure 8 The spiral shown.

[0074] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine different embodiments or examples described in this specification.

[0075] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A laser scanning path planning method, characterized in that: The following steps are involved: Establishing a three-dimensional model of the part to be formed, and slicing the three-dimensional model to obtain a plurality of slice layers; Acquire the data of the original contour line of any of the slice layers, perform offset processing on the original contour line of the slice layer inwards in sequence, finally obtain a plurality of contour lines, generate a contour line group corresponding to the slice layer, and number each contour line of the contour line group from the outside to the inside as i1, i2....in, where n≥2, including: perform equidistant offset processing on the original contour line of the slice layer inwards in sequence to obtain a plurality of contour lines, and the offset distance of the contour line is d; Each contour line of the contour line group is sequentially connected from the outside to the inside to form a spiral laser scanning path corresponding to each slice layer; The step of sequentially connecting each contour line of the contour line group from outside to inside to form a spiral laser scanning path corresponding to each slice layer includes: taking any point on the contour line i1 as an entry point, and making a tangent line of the contour line i1 from the entry point, wherein the angle between the tangent line and the preset straight line is σ; A tangent is drawn for each of the contour lines obtained by the offset, all the tangents are parallel to each other, and all the tangents are numbered L1, L2, L3, ..., Ln from the outside to the inside; Intersect the tangent line Lm+1 with the contour line im, and obtain the positions of the two intersection points of the tangent line Lm+1 and the contour line im, where 1≤m≤n; Taking the entry point of the contour line i1 as the starting point, laser scanning is performed along a first direction, the first direction being a clockwise or counterclockwise direction, taking the second intersection point where the contour line i1 and the tangent line L2 intersect in the first direction as the inflection point, and entering the contour line i2 along the tangent line L2; Scan along the first direction on the contour line im+1, and enter the contour line im+2 with the second intersection point where the contour line im+1 and the tangent line Lm+2 in the first direction as the turning point, and complete the laser scanning from the contour line i1 to the contour line in sequence, and connect the contour line group in series into a U-shaped spiral line.

2. The laser scanning path planning method according to claim 1, characterized in that: The tangent lines are drawn for each of the contour lines obtained by the offset, and all the tangent lines are parallel to each other; Specifically, a tangent is made for each of the offset contour lines, all of the tangents are parallel to each other, and the distance between every two adjacent tangents is D, and D is calculated by the inclination angle σ of the tangent L1 and the offset distance d.

3. The laser scanning path planning method according to claim 2, characterized in that: The distance D between two adjacent tangent lines is cosσ*(sinσ / cosσ*d+d).

4. The laser scanning path planning method according to claim 2, characterized in that: The tangent line Lm+1 is intersected with the contour line im to obtain the positions of the two intersection points of the tangent line Lm+1 and the contour line im; specifically: According to the inclination angle σ of the tangent line L1, the distance D between two adjacent tangent lines and the position of the entry point, starting from the contour line i2, make tangents for each contour line from the outside to the inside, find the intersection point of each tangent line Lm+1 with the contour line im, and record the position of the intersection point.

5. An additive manufacturing method, characterized in that: Using the laser scanning path planning method according to any one of claims 1 to 4 to plan the scanning path; By adopting the coaxial powder feeding method, laser scanning and deposition are performed on each slice layer of the part to be formed according to the planned scanning path, and the part to be formed is formed layer by layer.

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