A method for optimizing sharp corners in filling paths for additive manufacturing

Abstract

The present invention discloses a method for optimizing sharp corners in filling paths for additive manufacturing, comprising the following steps: slicing a model to obtain a slice contour polygon to be filled; filling the slice contour polygon, wherein when using oriented parallel straight lines to fill the path, the optimization goal is to maximize the angle between the path direction and the slice contour edge, generating a series of oriented parallel straight line segments that intersect the slice contour edge for filling; and when using an offset contour to fill the path, deleting the offset path within the sharp corner area and filling the sharp corner area with equidistant offset line segments to generate an equidistant path, which is then sequentially connected with the remaining offset paths to form a filling path for filling. This method reduces sharp corners by adjusting the path direction, thereby alleviating over-pile-up and improving the flatness of the additive surface.

Description

Technical Field

[0001] The invention relates to a method for optimizing sharp corners of a filling path used in additive manufacturing, and belongs to the technical field of additive manufacturing. Background Art

[0002] During additive manufacturing, for directional parallel straight line filling paths, there is a certain angle between the direction of the path and the edge of the slice contour. If the angle between the direction of the path and the edge of the slice contour is small, a sharp corner will appear; for offset contour filling paths, if the angle between adjacent edges of the slice contour is small, as the offset distance increases, the angle will gradually decrease to form a sharp corner. When the filling tool moves to a sharp corner, the direction of movement changes, and the movement speed will decrease from normal speed to turning speed. When it turns to the other direction, the movement speed will increase from turning speed to normal speed. If uniform material filling is performed at a sharp corner, due to the change in movement speed, material over-accumulation will occur at the sharp corner. Since the speed changes drastically at the sharp corner and the feeding mechanism responds slowly, it is difficult to avoid over-accumulation by adjusting the feeding speed. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to overcome the defects of the prior art and provide a method for optimizing the sharp corners of a filling path for additive manufacturing.

[0004] In order to solve the above technical problems, the technical solutions adopted by the present invention are as follows:

[0005] A method for optimizing fill path corners for additive manufacturing, comprising the following steps:

[0006] Step 1: Slice the model to obtain the slice outline polygons that need to be filled.

[0007] Step 2: Fill the slice contour polygon. When using oriented parallel straight lines to fill the path, the optimization goal is to maximize the angle between the path direction and the slice contour edge. Generate a series of oriented parallel straight line segments that intersect with the slice contour edge for filling.

[0008] When using an offset contour to fill a path, delete the offset path inside the sharp-angled area, use equidistant offset line segments to fill the sharp-angled area, generate an equidistant path, and connect it with the undelete offset path in sequence to form a fill path for filling.

[0009] Furthermore, in step 2, when using oriented parallel straight lines to fill the path, the angle between the path direction and the slice contour edge is maximized, satisfying the following formula:

[0010]

[0011] stxx=1

[0012] Where s i is the normalized length of the i-th slice contour edge, v i is the unit direction vector of the i-th slice contour edge, x is the unit direction vector of the path direction, and the value of x is solved by the formula;

[0013] Along the path direction, a series of directional parallel straight line segments intersecting with the slice contour edge are generated with the set filling spacing, and the starting and ending points of adjacent straight line segments are connected in sequence to generate a directional parallel straight line filling path.

[0014] Furthermore, the normalized length s of the i-th slice contour edge is i The calculation formula is,

[0015]

[0016] Where L is the total side length of the slice contour polygon, l i is the length of the contour edge of the i-th slice.

[0017] Furthermore, the unit direction vector v of the i-th slice contour edge i The calculation formula is,

[0018]

[0019] Where, is the direction vector of the i-th slice contour edge, l i is the length of the contour edge of the i-th slice.

[0020] Furthermore, in step 2, when the offset contour is used to fill the path, the following optimization steps are included:

[0021] Step 2.2.1: continuously offset the slice contour polygon inward according to the offset distance to generate an offset contour filling path;

[0022] Step 2.2.2 Detecting sharp corners: For any path point p on the offset contour filling path i Angle Among them, p i-1 and p i+1 Point p i The previous path point and the next path point, if the angle θ at the path point i Less than the sharp angle setting value Then determine the path point p i For the sharp corner point;

[0023] Step 2.2.3 Group the nearest corner points of adjacent offset contour filling paths into a group in the order from the slice contour polygon, i.e. the slice contour boundary to the inside of the filling area. in, is the path point p i The corresponding j group of offset contours fills the sharp corner points of path k;

[0024] by is the center of the circle, and distance Draw a circle with a radius of and in, is the waypoint o i The corresponding j groups of offset contours fill the sharp corner points of path k, is the waypoint q i The corresponding j groups of offset contours fill the sharp corner points of path k, The offset path segment straight line segment straight line segment and offset path segments The enclosed area is the sharp corner area;

[0025] Step 2.2.5 Delete the offset path inside the sharp corner area and use equidistant offset line segments To fill the sharp-angle area, generate an equidistant path, and connect it with the undeleted offset path in sequence according to the principle of the closest distance between adjacent offset path points to form a filling path.

[0026] Furthermore, the sharp angle setting value

[0027] Furthermore, the sharp angle setting value The steps to determine are:

[0028] Set sharp corners The angle is α, the cusp point The angle is β, then

[0029] like Then β = α, and the generated bias path has sharp corners;

[0030] like Then β>α, and the generated offset path points do not have sharp corners;

[0031] Therefore, the sharp angle setting value Set to

[0032] The beneficial effects achieved by the present invention are:

[0033] The present invention discloses a method for optimizing sharp corners in a filling path for additive manufacturing. By planning the filling path and adjusting the path direction to reduce sharp corners, this method avoids material accumulation at the sharp corners due to a sudden change in the direction of movement when the additive manufacturing filling moves to the sharp corners. This method can reduce the over-accumulation phenomenon and improve the flatness of the additive surface. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a schematic diagram of a directional parallel straight line filling path;

[0035] Figure 2 This is a schematic diagram of the parallel straight line filling path without sharp corners after optimization by this method;

[0036] Figure 3 It is a schematic diagram of the offset contour filling path;

[0037] Figure 4 It is a schematic diagram of the sharp corner area formed by the sharp corner points;

[0038] Figure 5 It is a schematic diagram of the sharp angle setting value;

[0039] Figure 6 This is a schematic diagram of the non-sharp-corner offset contour filling path after optimization by this method. DETAILED DESCRIPTION

[0040] The present invention will be further described below in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention.

[0041] This embodiment discloses a method for optimizing fill path corners for additive manufacturing, comprising the following steps:

[0042] Step 1: Slice the model to obtain the slice outline polygons that need to be filled.

[0043] Step 2: For directional parallel straight line fill paths or offset contour fill paths, use different methods to reduce sharp corners.

[0044] When filling a path with oriented parallel lines, the angle between the path direction and the slice contour edge is calculated to be the largest, thereby reducing sharp corners.

[0045] When using an offset outline to fill a path, the sharp corners are reduced by adjusting the path shape in the sharp corner area.

[0046] Specifically, when a path is filled using directional parallel straight lines, the following steps are specifically included:

[0047] Step 2.1: For directional parallel straight line filling paths, Figure 1As shown in the figure, by calculating the maximum angle between the path direction and the slice contour edge, the sharp angle is reduced. Orientation is a fixed direction. The angle between the direction of the parallel line and the X-axis is a fixed direction, such as 30 degrees or 60 degrees.

[0048] 2.1.1 First, normalize the lengths of the sides of the slice contour polygon as shown below:

[0049]

[0050] Where L is the total side length of the slice contour, l i is the length of the contour edge of the i-th slice, s i is the normalized length of the contour edge of the i-th slice.

[0051] 2.1.2 Then calculate the unit direction vector v of the i-th slice contour edge i

[0052]

[0053] in, is the direction vector of the i-th slice silhouette edge.

[0054] 2.1.3 Finally, maximize the angle between the path direction and the slice contour edge to satisfy the following formula:

[0055]

[0056] stxTx=1

[0057] Where x is the unit direction vector of the path direction, and the value of x is solved using the following formula.

[0058] 2.1.4 Generate a series of oriented parallel straight line segments that intersect with the slice contour edge along the path direction and filling spacing, and then connect the starting and ending points of adjacent straight line segments in sequence to generate a oriented parallel straight line filling path, such as Figure 2 shown.

[0059] When using offset contour to fill a path, the following steps are included:

[0060] Step 2.2: For the offset contour filling path, Figure 3 As shown, the sharp corners can be reduced by adjusting the path form in the sharp corner area.

[0061] 2.2.1 First, according to the offset distance, the slice contour polygon is continuously offset inward to generate an offset contour filling path.

[0062] 2.2.2 Then detect the sharp corners. For any path point p on the offset contour filling path, i Angle Among them, p i-1 and p i+1 Point p i The previous path point and the next path point. If the angle θ at the path point i Less than the set value Then the path point is a sharp corner point, that is p i For sharp corners.

[0063] 2.2.3 The nearest corner points of adjacent offset contour filling paths are grouped into a group in the order from the slice contour polygon, i.e. the slice contour boundary to the inside of the filling area. in, is the path point p i The corresponding j group of offset contours fills the sharp corner points of path k;

[0064] by is the center of the circle, and distance Draw a circle with a radius of and in, is the waypoint o i The corresponding j groups of offset contours fill the sharp corner points of path k, is the waypoint q i The corresponding j groups of offset contours fill the sharp corner points of path k, The offset path segment straight line segment straight line segment and offset path segments The enclosed area is the sharp corner area.

[0065] 2.2.4 Assuming a sharp corner point The angle is α, point The angle is β, such as Figure 5 As shown, if Then β=α, then the generated bias path still has sharp corners; if If β>β, then the generated offset path point does not have sharp corners. Therefore, the setting value of the sharp corner

[0066] 2.2.5 Delete the offset path inside the sharp corner area and use equidistant offset line segments To fill the sharp corner area, generate an equidistant path, and connect the undeleted offset paths in sequence according to the principle of the closest distance between adjacent offset path points to form a filling path, such as Figure 6 shown.

[0067] By planning the filling path and adjusting the path direction to reduce sharp corners, the accumulation of material at the sharp corners caused by the sudden change in movement direction when the additive manufacturing filling moves to the sharp corners can be avoided. This can reduce the over-accumulation phenomenon and improve the flatness of the additive surface, especially at the sharp corners.

[0068] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for optimizing fill path corners for additive manufacturing, characterized in that: The following steps are involved: Step 1: Slice the model to obtain the slice outline polygons that need to be filled; Step 2: Fill the slice contour polygon. When using oriented parallel straight lines to fill the path, the optimization goal is to maximize the angle between the path direction and the slice contour edge. Generate a series of oriented parallel straight line segments that intersect with the slice contour edge for filling. When using an offset contour to fill a path, delete the offset path inside the sharp-angled area, use equidistant offset line segments to fill the sharp-angled area, generate an equidistant path, and connect it with the undelete offset path in sequence to form a fill path for filling.

2. A method for optimizing fill path corners for additive manufacturing according to claim 1, characterized in that: In step 2, when using directional parallel straight lines to fill the path, the angle between the path direction and the slice contour edge is maximized, satisfying the following formula: Where s i is the normalized length of the i-th slice contour edge, v i is the unit direction vector of the i-th slice contour edge, x is the unit direction vector of the path direction, and the value of x is solved by the formula; Along the path direction, a series of directional parallel straight line segments intersecting with the slice contour edge are generated with the set filling spacing, and the starting and ending points of adjacent straight line segments are connected in sequence to generate a directional parallel straight line filling path.

3. The method for optimizing fill path corners for additive manufacturing according to claim 2, wherein: The normalized length s of the i-th slice contour edge i The calculation formula is, Where L is the total side length of the slice contour polygon, l i is the length of the contour edge of the i-th slice.

4. A method for optimizing fill path corners for additive manufacturing according to claim 2 or 3, characterized in that: The unit direction vector v of the i-th slice silhouette edge i The calculation formula is, Where, is the direction vector of the i-th slice contour edge, l i is the length of the contour edge of the i-th slice.

5. The method for optimizing fill path corners for additive manufacturing according to claim 1, wherein: In step 2, when using offset contour filling path, the following optimization steps are included: Step 2.2.1: continuously offset the slice contour polygon inward according to the offset distance to generate an offset contour filling path; Step 2.2.2 Detecting sharp corners: For any path point p on the offset contour filling path i Angle Among them, p i-1 and p i+1 Point p i The previous path point and the next path point, if the angle θ at the path point i Less than the sharp angle setting value Then determine the path point p i For the sharp corner point; Step 2.2.3 Group the nearest corner points of adjacent offset contour filling paths into a group in the order from the slice contour polygon, i.e. the slice contour boundary to the inside of the filling area. in, is the path point p i The corresponding j group of offset contours fills the sharp corner points of path k; by is the center of the circle, and distance Draw a circle with a radius of and in, is the waypoint o i The corresponding j groups of offset contours fill the sharp corner points of path k, is the waypoint q i The corresponding j groups of offset contours fill the sharp corner points of path k, The offset path segment straight line segment straight line segment and offset path segments The enclosed area is the sharp corner area; Step 2.2.5 Delete the offset path inside the sharp corner area and use equidistant offset line segments To fill the sharp-angled area, generate an equidistant path, and connect the undeleted offset paths into a filling path in sequence based on the principle of the closest distance between adjacent offset path points.

6. The method for optimizing fill path corners for additive manufacturing according to claim 5, wherein: Sharp angle setting value 7. The method for optimizing fill path corners for additive manufacturing according to claim 6, wherein: Sharp angle setting value The steps to determine are: Set sharp corners The angle is α, the cusp point The angle is β, then like Then β = α, and the generated bias path has sharp corners; like Then β>α, and the generated offset path points do not have sharp corners; Therefore, the sharp angle setting value Set to

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