EP4655653A1

EP4655653A1 - Method for generating toolpath, and system for generating toolpath and computer-readable storage medium thereof

Info

Publication number: EP4655653A1
Application number: EP23924694.5A
Authority: EP
Inventors: Kai Wang
Original assignee: Siemens Industry Software Inc
Current assignee: Siemens Industry Software Inc
Priority date: 2023-03-02
Filing date: 2023-03-02
Publication date: 2025-12-03
Also published as: WO2024178727A1; CN120604184A

Abstract

Disclosed is a method for generating a toolpath of a tool for fixed shaft milling. The method includes: inputting a workpiece geometry, the workpiece geometry including a milling region; defining a region falling within the same range of height and communicated with the milling region on the workpiece geometry as an auxiliary region, the height being a height defined along an orientation of a tool axis; defining a combined region of the milling region and the auxiliary region as a transition region; generating a spiral toolpath of the transition region; and replacing a portion for milling the auxiliary region in the spiral tool path with a non-milling toolpath. The method is favorable to improving uniformity of the toolpath. Further disclosed is a system for generating a toolpath and computer-readable storage medium thereof.

Description

METHOD FOR GENERATING TOOLPATH, AND SYSTEM FOR GENERATING TOOLPATH AND COMPUTER-READABLE STORAGE MEDIUM THEREOF

TECHNICAL FIELD

The present disclosure relates to methods for generating toolpaths, and in particular, relates to a method for generating a toolpath for fixed shaft milling, and a system for generating a toolpath and a computer-readable storage medium thereof.

BACKGROUND

In a conventional method for generating the toolpath for fixed shaft milling, a generated spiral toolpath is partially congested and dents tend to be formed on the surface of a machined workpiece in the case that the tool is applied to the workpiece in which, along a circumferential direction perpendicular to the direction of the tool axis, a portion of the milling region is contiguous whereas the other portion is not contiguous.
SUMMARY
One object of the present disclosure is to provide a method for generating a toolpath. With the method, uniformity of the toolpath is improved in the case that the tool is applied to a workpiece in which, along a circumferential direction perpendicular to the direction of the tool axis, a portion of the milling region is contiguous whereas the other portion is not contiguous.
Another object of the present disclosure is to provide a computer-readable storage medium. With the storage medium, uniformity of the toolpath is improved in the case that the tool is applied to a workpiece in which, along a circumferential direction perpendicular to the direction of the tool axis, a portion of the milling region is contiguous whereas the other portion is not contiguous.
Still another object of the present disclosure is to provide a system for generating a toolpath. With the system, uniformity of the toolpath is improved in the case that the tool is applied to a workpiece in which, along a circumferential direction perpendicular to the direction of the tool axis, a portion of the milling region is contiguous whereas the other portion is not contiguous.
Some specific embodiments of the present disclosure provide a method for generating a toolpath of a tool for fixed shaft milling. The method includes:
inputting a workpiece geometry, the workpiece geometry including a milling region;
defining a region falling within the same range of height and communicated with the milling region on the workpiece geometry as an auxiliary region, the height being a height defined along a direction of a tool axis;
defining a combined region of the milling region and the auxiliary region as a transition region;
generating a spiral toolpath of the transition region; and
replacing a portion for milling the auxiliary region in the spiral tool path with a non-milling toolpath.
With the method for generating the toolpath, uniformity of the toolpath is improved in the case that the tool is applied to a workpiece in which, along a circumferential direction perpendicular to the direction of the tool axis, a portion of the milling region is contiguous whereas the other portion is not contiguous.
In one exemplary embodiment of the method for generating the toolpath, the step of generating the constant Z toolpath of the transition region includes:
generating a constant Z toolpath of the transition region, the constant Z toolpath including several closed curves, each of the closed curves corresponding to a milling layer;
generating, between each two adjacent closed curves of the closed curves, a spiral curve connecting the two closed curves, each two adjacent spiral curves of the spiral curves being connected to the same point of the closed curves, and each of the spiral curves being such defined that in the case that a tip point of the tool moves along the spiral curve, the tool is constantly in contact with the transition region; and
forming the spiral toolpath by connecting two closed curves at two ends and all the spiral curves.
In another exemplary embodiment of the method for generating the toolpath, the step of generating the constant Z toolpath of the transition region includes:
moving the tool towards the transition region along the direction of the tool axis, and stop moving the tool in response to being contact with the transition region;
generating a three-dimensional grid according to a set of coordinates of the tip point of the tool in response to the tool being in contact with the transition region; and
acquiring the constant Z toolpath by calculating closed curves of the several milling layers based on the three-dimensional grid.
In still another exemplary embodiment of the method for generating the toolpath, generating, between each two adjacent closed curves of the closed curves, the spiral curve connecting the two closed curves includes:
determining corresponding points on a lower closed curve in each two adjacent curves of the closed curves along a normal direction of discrete points on an upper closed curve in each two adjacent closed curves of the closed curves, and connecting each two corresponding points by a line segment to form a transition line;
selecting a discrete point on an uppermost closed curve as a connection point for connecting the spiral curve;
successively determining, from top to bottom, the discrete point on each of the closed curves that is connected to the connection point on the upper closed curve thereof by the transition line, and determining the discrete point as the connection point for connecting the spiral curve;
projecting each of the transition lines to the three-dimensional grid along the direction of the tool axis to form a transition projection line; and
with respect to each two adjacent closed curves of the closed curves, determining a point on the transition projection line connecting the two closed curves, and connecting the points by line segments to form the spiral curve.
In yet still another exemplary embodiment of the method for generating the toolpath, a height of each section on the spiral curve along the direction of the tool axis is proportional to a ratio of a corresponding section thereof on the upper closed curve to the closed curve. In this way, uniformity of the toolpath is improved, and milling quality is enhanced.
In yet still another exemplary embodiment of the method for generating the toolpath, a discrete point with a minimum curvature is selected on the uppermost closed curve as the connection point for connecting the spiral curve. In this way, the tool may be inserted at a relatively smooth position, and milling quality is enhanced
In yet still another exemplary embodiment of the method for generating the toolpath, prior to generating the spiral toolpath of the transition region, the workpiece geometry is discretized into a triangular patch model. In this way, subsequent operations are facilitated.
In yet still another exemplary embodiment of the method for generating the toolpath, the spiral toolpath of the transition region is generated by using a CAM module of Siemens NX software. In this way, efficiency is improved.
Some specific embodiments of the present disclosure further provide a computer-readable storage medium storing a computer program therein, wherein the computer program, when loaded and run by a processor, causes the processor to perform the method for generating the toolpath as described above. In this way, uniformity of the toolpath is improved in the case that the tool is applied to a workpiece in which, along a circumferential direction perpendicular to the direction of the tool axis, a portion of the milling region is contiguous whereas the other portion is not contiguous.
Some specific embodiments of the present disclosure further provide a modeling system for a tubular structure. The system includes a processor and a memory storing a computer program, wherein the processor, when loading and running the computer program, is caused to perform the method for generating the toolpath as described above. In this way, uniformity of the toolpath is improved in the case that the tool is applied to a workpiece in which, along a circumferential direction perpendicular to the direction of the tool axis, a portion of the milling region is contiguous whereas the other portion is not contiguous.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are merely for schematic and illustrative description and demonstration of the present disclosure, instead of limiting the scope of the present disclosure.
FIG. 1 to FIG. 4 are flowcharts of a method for generating a toolpath of a tool according to one exemplary embodiment of the present disclosure;
FIG. 5 to FIG. 12 are schematic diagrams of a method for generating a toolpath of a tool according to one exemplary embodiment of the present disclosure; and
FIG. 13 is a flowchart of a method for generating a toolpath of a tool according to another exemplary embodiment of the present disclosure.
Reference numerals and denotations thereof:
100–workpiece geometry
101–milling region
102–auxiliary region
S–direction of tool axis
10–three-dimensional grid
20–constant Z toolpath
21–closed curve
31–spiral curve
40–spiral toolpath curve
50–non-milling toolpath
61–transition line
62–transition projection line

DETAILED DESCRIPTION

For clearer descriptions of the technical features, objects, and the technical effects of the present disclosure, the specific embodiments of the present disclosure are hereinafter described with reference to the accompanying drawings. In the drawings, like reference numerals denote elements having the same structure or having the similar structure but the same function.
In this text, the term "exemplary" or "schematic" is used herein to mean "serving as an example, instance, or illustration, " and any illustration or embodiment described herein as "exemplary" shall not be necessarily construed as preferred or advantageous over other illustrations or embodiments.
For brevity, parts relevant to the present disclosure are merely illustrated in the drawings, and these parts do not denote the actual structure of the product.
FIG. 1 to FIG. 4 are flowcharts of a method for generating a toolpath of a tool according to one exemplary embodiment of the present disclosure. The method is applicable to fixed shaft milling. As illustrated in FIG. 1, the method includes steps S10 to S50.
In S10, a workpiece geometry is input. As illustrated in FIG. 5, a workpiece geometry 100 includes a milling region 101 (that is, the region that is not indicated by dot hatching in FIG. 5) . In an exemplary embodiment, the milling region 101 is a region forming an included angle of more than 65 degrees with a horizontal direction (the horizontal direction is perpendicular to a direction S of a tool axis) . The region forming an included angle of less than 65 degrees with the horizontal direction is indicated by dot hatching and is a non-milling region, which is, however, not limited hereto. In some other exemplary embodiments, a range of the milling region may be adjusted according to actual needs. In this exemplary embodiment, the input workpiece geometry 100 is a triangular patch model. For clear illustration in the drawings, in FIGS. 5 to 8 and FIGS. 10 to 12, no triangular patch model is drawn for the workpiece geometry 100, and a simplified version of the triangular patch model is illustrated.
In S20, a region falling within the same range of height and communicated with the milling region 101 on the workpiece geometry 100 is defined as an auxiliary region 102. In this exemplary embodiment, the auxiliary region 102 is a region that is dot hatched. The height is a height defined along the direction S of the tool axis.
In S30, a combined region of the milling region 101 and the auxiliary region 102 is defined as a transition region.
In S40, a spiral toolpath of the transition region is generated.
Specifically, as illustrated in FIG. 2, step S40 includes the following steps S41 to S43, to improve uniformity of the toolpath.
In S41, a constant Z toolpath of the transition region is generated, wherein the constant Z toolpath includes several closed curves, each of the closed curves corresponding to a milling layer.
Specifically, as illustrated in FIG. 3, step S41 includes the following steps S411 to S413, to improve accuracy of the toolpath.
In S411, the tool is moved towards the transition region along the direction S of the tool axis, and the moving of the tool is stopped in response to being contact with the transition region.
In S412, a three-dimensional grid 10 as illustrated in FIG. 6 is generated according to a set of coordinates of the tip point of the tool in response to the tool being in contact with the transition region.
In S413, referring to FIG. 7, a constant Z toolpath 20 is acquired by calculating closed curves 21 (FIG. 7 merely schematically illustrates one of the closed curves 21) of the several milling layers based on the three-dimensional grid 10. This step may be understood as follows: The closed curves 21 are formed by intersection between several planes perpendicular to the direction S of the tool axis and the three-dimensional grid 10, and an equal distance is defined between each two adjacent planes.
In S42, a spiral curve connecting the two closed curves is generated between each two adjacent closed curves 21 of the closed curves 21, wherein each two adjacent spiral curves of the spiral curves are connected to the same point of the closed curves 21, and each of the spiral curves is such defined that in the case that a tip point of the tool moves along the spiral curve, the tool is constantly in contact with the transition region.
Specifically, as illustrated in FIG. 4, step S42 includes the following steps S421 to S425, to improve accuracy of the spiral curve.
In S421, referring to FIG. 8, corresponding points on a lower closed curve 21 in each two adjacent curves 21 of the closed curves 21 along a normal direction of discrete points P on an upper closed curve 21 in each two adjacent closed curves 21 of the closed curves 21 determined, and each two corresponding points are connected by a line segment to form a transition line 61. FIG. 8 merely schematically illustrates one transition line 61 and two discrete points P connected thereto.
In S422, a discrete point P on an uppermost closed curve 21 is selected as a connection point for connecting the spiral curve. In an exemplary embodiment, a discrete point P with a minimum curvature is selected on the uppermost closed curve 21 as the connection point for connecting the spiral curve. In this way, the tool may be inserted at a relatively smooth position, and milling quality is enhanced
In S423, the discrete point P on each of the closed curves 21 that is connected to the connection point on the upper closed curve 21 thereof by the transition line 61 is successively determining, from top to bottom, and the discrete point is determined as the connection point for connecting the spiral curve.
In S424, referring to FIG. 9, each of the transition lines 61 is projected into the three-dimensional grid 10 to form a transition projection line 62. FIG. 9 merely schematically illustrates two transition lines 61 (drawn by dotted lines) , two transition projection lines 62 (drawn by dashed-dotted lines) , and discrete points P connected thereto.
In S425, referring to FIG. 9, with respect to each two adjacent closed curves 21 of the closed curves 21, a point Q on the transition projection line 62 connecting the two closed curves 21, and the points are connected by line segments to form the spiral curve. Formed spiral curves 31 are represented by the dotted lines in FIG. 10 (FIG. 10 merely schematically illustrates one of the spiral curves 31) . In an exemplary embodiment, a height of each section (for example, the line segment connecting two points Q in FIG. 9) on the spiral curve 31 along the direction of the tool axis is proportional to a ratio of a corresponding section (that is, the section between two upper discrete points in FIG. 9) thereof on the upper closed curve 21 to the closed curve 21 (that is, the upper closed curve 21 in FIG. 9) . In this way, uniformity of the toolpath is improved, and milling quality is enhanced.
In S43, a spiral toolpath 40 is formed by connecting two closed curves 21 at two ends and all the spiral curves 31. The formed spiral toolpath 40 is as illustrated in FIG. 11.
In S50, a portion for milling the auxiliary region 102 in the spiral tool path 40 is replaced with a non-milling toolpath 50. FIG. 12 illustrates a state upon the replacement. In the path, the dotted-line portion represents the non-milling toolpath 50, and the solid-line portion represents the remaining spiral toolpath 40. By adding a tool insertion path and a tool exit path upon combination of the non-milling toolpath 50 and the spiral toolpath 40, the toolpath for machining the workpiece geometry 100 is formed.
With the method for generating the toolpath, uniformity of the toolpath is improved in the case that the tool is applied to a workpiece (for example, the workpiece illustrated in FIG. 5) in which, along a circumferential direction perpendicular to the direction of the tool axis, a portion of the milling region is contiguous whereas the other portion is not contiguous.
In an exemplary embodiment, the spiral toolpath of the transition region is generated by using, for example, a CAM module of Siemens NX software. In this way, efficiency is improved.
FIG. 13 is a flowchart of a method for generating a toolpath of a tool according to another exemplary embodiment of the present disclosure. The method for generating the toolpath according to this exemplary embodiment is different from the above method for generating the toolpath in addition of step S60. In S60, specifically, prior to generating the spiral toolpath of the transition region, the workpiece geometry is discretized into a triangular patch model. In this way, subsequent operations are facilitated. In this exemplary embodiment, the input workpiece geometry is a physical model, which is transformed into a triangular patch model upon processing by step S60.
Some specific embodiments of the present disclosure further provide a computer-readable storage medium storing a computer program therein, wherein the computer program, when loaded and run by a processor, causes the processor to perform the method for generating the toolpath as described above. In this way, uniformity of the toolpath is improved in the case that the tool is applied to a workpiece in which, along a circumferential direction perpendicular to the direction of the tool axis, a portion of the milling region is contiguous whereas the other portion is not contiguous.
Some specific embodiments of the present disclosure further provide Embodiments of the present disclosure further provide a modeling system for a tubular structure. The system includes a processor and a memory storing a computer program, wherein the processor, when loading and running the computer program, is caused to perform the method for generating the toolpath as described above. In this way, uniformity of the toolpath is improved in the case that the tool is applied to a workpiece in which, along a circumferential direction perpendicular to the direction of the tool axis, a portion of the milling region is contiguous whereas the other portion is not contiguous.
It should be understood that, although this specification is described based on the embodiments, not each of the embodiments discloses an independent technical solution. Such description manner of the specification is only for clarity. A person skilled in the art should consider the specification as an entirety. The technical solutions according to the embodiments may also be suitably combined to derive other embodiments that may be understood by a person skilled in the art.
A series of detailed descriptions given in this specification are merely intended to illustrate feasible embodiments of the present disclosure, instead of limiting the protection scope of the present disclosure. Any equivalent embodiments or modifications, for example, combinations, segmentations, or repetition of features, derived without departing from the spirit of the present disclosure shall fall within the protection scope of the present disclosure.

Claims

A method for generating a toolpath of a tool for fixed shaft milling, comprising:

inputting a workpiece geometry, the workpiece geometry comprising a milling region;

defining a region falling within the same range of height and communicated with the milling region on the workpiece geometry as an auxiliary region, the height being a height defined along a direction of a tool axis;

defining a combined region of the milling region and the auxiliary region as a transition region;

generating a spiral toolpath of the transition region; and

replacing a portion for milling the auxiliary region in the spiral tool path with a non-milling toolpath.
The method according to claim 1, wherein the step of generating the spiral toolpath of the transition region comprises:

generating a constant Z toolpath of the transition region, the constant Z toolpath comprising a plurality of closed curves, each of the closed curves corresponding to a milling layer;

generating, between each two adjacent closed curves of the closed curves, a spiral curve connecting the two closed curves, each two adjacent spiral curves of the spiral curves being connected to the same point of the closed curves, and each of the spiral curves being such defined that in the case that a tip point of the tool moves along the spiral curve, the tool is constantly in contact with the transition region; and

forming the spiral toolpath by connecting two closed curves at two ends and all the spiral curves.
The method according to claim 2, wherein the step of generating the constant Z toolpath of the transition region comprises:

moving the tool towards the transition region along the direction of the tool axis, and stop moving the tool in response to being in contact with the transition region;

generating a three-dimensional grid according to a set of coordinates of the tip point of the tool in response to the tool being in contact with the transition region; and

acquiring the constant Z toolpath by calculating the closed curves of the milling layers based on the three-dimensional grid.
The method according to claim 3, wherein the step of generating, between each two adjacent closed curves of the closed curves, the spiral curve connecting the two closed curves comprises:

determining corresponding points on a lower closed curve in each two adjacent curves of the closed curves along a normal direction of discrete points on an upper closed curve in each two adjacent closed curves of the closed curves, and connecting each two corresponding points by a line segment to form a transition line;

selecting a discrete point on an uppermost closed curve as a connection point for connecting the spiral curve;

successively determining, from top to bottom, the discrete point on each of the closed curves that is connected to the connection point on the upper closed curve thereof by the transition line, and determining the discrete point as the connection point for connecting the spiral curve;

projecting each of the transition lines to the three-dimensional grid along the direction of the tool axis to form a transition projection line; and

with respect to each two adjacent closed curves of the closed curves, determining a point on the transition projection line connecting the two closed curves, and connecting the points by line segments to form the spiral curve.
The method according to claim 4, wherein a height of each section on the spiral curve along the direction of the tool axis is proportional to a ratio of a corresponding section thereof on the upper closed curve to the closed curve.
The method according to claim 4, wherein a discrete point with a minimum curvature is selected on the uppermost closed curve as the connection point for connecting the spiral curve.
The method according to claim 1, wherein prior to generating the spiral toolpath of the transition region, the workpiece geometry is discretized into a triangular patch model.
The method according to claim 1, wherein the spiral toolpath of the transition region is generated by using a CAM module of Siemens NX software.
A computer-readable storage medium storing a computer program therein, wherein the computer program, when loaded and run by a processor, causes the processor to perform the method for generating the toolpath as defined in any one of claims 1 to 8.
A system for generating a toolpath of a tool for fixed shaft milling, comprising: a processor and a memory storing a computer program, wherein the processor, when loading and running the computer program, is caused to perform the method for generating the toolpath as defined in any one of claims 1 to 8.