A method, device and storage medium for generating a side milling tool path with an inclination angle

Abstract

The application relates to the technical field of side blade machining, in particular to a side milling machining tool path generation method with an inclination angle, a device and a storage medium. Compared with the prior art, the technical scheme provided by the application has the beneficial effects as follows: a segmented tool path structure is used, tool path splicing is realized through an inserted transition section tool path, and a machining tool position point is obtained; a step-by-step approximation method is used to iterate the tool axis direction back and forth between two cone surfaces, the intersection line of the two cone surfaces is finally obtained, and the intersection line is used as the tool axis direction of the inflection point position of the tool path.

Description

Technical Field

[0001] This invention relates to the field of side milling technology, and more specifically, to a method, equipment, and storage medium for generating toolpaths for side milling with an angle. Background Technology

[0002] Side-cutting is an efficient and practical method for machining curved surfaces. However, it's not suitable for complex surfaces such as non-ruled or non-developable ruled surfaces. In such cases, a tilt angle can be specified for the side-cutting toolpath, transforming it into point milling and enabling high-precision machining of complex surfaces. During side-cutting, a tilt angle is also specified for the toolpath to avoid tool collisions. Furthermore, the tapered end mill used in side-cutting naturally has a fixed angle with the guide surface. The tilt angle affects the machining accuracy of curved surfaces at corner positions; without proper handling, it can lead to overcutting or undercutting.

[0003] When machining non-ruled surfaces or considering tool avoidance factors, a tilt angle is added to the side cutting edge toolpath. For a single guide surface, adding a tilt angle to the toolpath only requires adding an additional included angle to the tool axis; however, for connected guide surfaces, the tool axis direction at the corner is generally difficult to determine. A common method is to leave a certain machining allowance at the corner and then perform root / corner clearing. To obtain an accurate solution, a geometric intersection method is generally used. A conical surface is constructed at the corner, and the intersection line of the conical surfaces is obtained through geometric intersection. The direction of the intersection line is used as the tool axis direction. This method relies on a geometric kernel, and the intermediate process involves modeling and intersection calculations. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and to propose an algorithm for quickly determining the tool axis direction at corner positions based on numerical calculation, and to apply this algorithm to the generation of side cutting toolpaths.

[0005] To achieve the above objectives, the present invention provides a method for generating toolpaths for side milling with tilt angles, the specific steps of which are as follows:

[0006] S1. Specify the current machining surface or guide surface;

[0007] S2. User-specified or automatically generated original processing line;

[0008] S3. Generate the actual machining line based on factors such as layering, offset, and compensation;

[0009] S4. Insert a transition section into the actual machining line, determine the machining tool position point, and use the successive approximation method to determine the tool axis direction;

[0010] S5. The toolpaths in step S4 are spliced ​​together to form the final five-axis side-edge machining toolpath.

[0011] Preferably, step S4 includes step S41, which is specifically as follows:

[0012] S41. Insert transition section: Divide each guide surface machining section into three sections, namely the front transition section, the middle section and the rear transition section.

[0013] Preferably, step S4 includes step S42, which is specifically as follows:

[0014] S42. Insert a transition segment to complete the splicing of the toolpaths, and perform corresponding processing on toolpath intersections, toolpath extensions, and toolpath fillets respectively.

[0015] Preferably, step S4 includes step S43, which is specifically as follows:

[0016] S43. Calculate the tool position point of the transition section: The tool position point of the intermediate section is the tool head coordinate, which is directly obtained from the machining line; for the transition section, the corner of the intersecting toolpath can be directly used as the tool position point; the tool position point of the extended toolpath or rounded toolpath can be obtained by discretization.

[0017] Preferably, step S4 includes step S44, which is specifically as follows:

[0018] S44. The tool axis direction of the transition section is calculated using the successive approximation method: the tool axis of the intermediate section is determined by the direction of the generatrix of the current guide surface tangent or ruled surface. If there is a side tilt angle, the tool axis is rotated.

[0019] The tool axis of the transition section: The transition section consists of inflection points, fillets, or extension lines. The tool axis of the inflection point is obtained by successive approximation. The extension line is the line connecting the end of the middle section to the inflection point, and the tool axis is obtained by linear interpolation. The tool axis of the fillet is in the same direction as the tool axis of the inflection point to ensure the continuity of the tool axis and the consistency of the layering. Finally, the tool axis direction of the entire transition section is calculated.

[0020] The present invention also provides a computer device, the computer device including a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that the processor executes the program to implement the steps of the above method.

[0021] The present invention also provides a computer-readable storage medium having a computer program stored thereon, characterized in that: when the program is executed by a processor, it implements the steps of the above method.

[0022] Compared with the prior art, the technical solution proposed in this application has the following beneficial effects: by using a segmented toolpath structure, toolpath splicing is achieved by inserting transitional toolpath segments, and machining tool positions are obtained; by using a stepwise approximation method, the tool axis direction is iterated back and forth between two conical surfaces, and finally the intersection line of the two conical surfaces is obtained, and the intersection line is used as the tool axis direction at the inflection point of the toolpath. Attached Figure Description

[0023] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0024] Figure 1 This is a schematic diagram of the toolpath for side-edge machining according to the present invention;

[0025] Figure 2 This is a schematic diagram of the processing line and transition section of the present invention;

[0026] Figure 3 This is a schematic diagram of the spliced ​​toolpath structure of the present invention;

[0027] Figure 4 This is a schematic diagram showing the tool axis direction and tilt angle at the inflection point of the present invention;

[0028] Figure 5 This is a schematic diagram illustrating the geometric constraint relationship of the roll angle in this invention;

[0029] Figure 6 This is a schematic diagram of the rootless (A+B+C>π) method of the present invention;

[0030] Figure 7 This is a schematic diagram of a single root (A+B+C=π) according to the present invention;

[0031] Figure 8 This is a schematic diagram of the double root (A+B+C<π) of the present invention;

[0032] Figure 9 This is a schematic diagram of the successive approximation of the present invention;

[0033] Figure 10 This is an iterative flowchart of the present invention;

[0034] Figure 11 This is an iterative schematic diagram of the present invention;

[0035] Figure 12 This is a schematic diagram of the included angle difference and iteration points of the present invention;

[0036] Figure 13 This is a schematic diagram of three iteration points in a single iteration process of the present invention;

[0037] Figure 14The graph of the rootless function (A+B+C>π) of this invention;

[0038] Figure 15 The graph of the single root function (A+B+C=π) of this invention;

[0039] Figure 16 This is the graph of the double-root function of the present invention (A+B+C<π). Detailed Implementation

[0040] The technical solutions in the embodiments of the present invention will be clearly and completely described and discussed below with reference to the accompanying drawings. Obviously, what is described here is only a part of the examples of the present invention, not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the protection scope of the present invention.

[0041] It should be noted that when a component is described as "fixed to" another component, it can be directly on the other component or may have a component in between. When a component is considered "connected to" another component, it can be directly connected to the other component or may have a component in between. When a component is considered "set on" another component, it can be directly set on the other component or may have a component in between. The terms "vertical," "horizontal," "left," "right," and similar expressions used in this document are for illustrative purposes only.

[0042] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0043] Example 1

[0044] First, the terms used in this embodiment are explained as follows:

[0045] Side-cutting milling: This method uses the side edge of the cutting tool as the cutting edge to machine along the curved surface, resulting in a smoother surface finish. It is a highly efficient and precise surface machining method, particularly suitable for the finishing of complex curved surfaces.

[0046] Guide surface: The target surface for side-cutting machining, and also the constraint surface for the machining toolpath. Generally speaking, the guide surface consists of a set of connected surfaces.

[0047] Side tilt angle: The angle between the tool axis and the guide surface. In side cutting, the side tilt angle can be used in conjunction with an appropriate tool head to transform side cutting into point milling, which is used to process some non-ruled surfaces or surfaces that cannot be developed; sometimes, a side tilt angle is also actively added to the toolpath to avoid collisions.

[0048] Tapered end mills: Tapered end mills occupy an important position in the metalworking industry due to their versatility, low cost, high efficiency, and high-quality machining capabilities. Their wide range of applications and reliable performance make them an indispensable tool in manufacturing and machining. Compared to ordinary end mills, tapered end mills naturally have a fixed angle with the guide surface.

[0049] Tool position point: The tool position point refers to the point used to represent the characteristics of the tool during programming and machining, and it is also the reference point for tool setting and machining. For various end mills, it is generally the intersection of the tool axis and the bottom of the tool; for turning tools, it is the tool tip; and for drill bits, it is the drill tip.

[0050] See Figure 1 This embodiment provides a method for generating toolpaths for side milling with tilt angles:

[0051] Specify the machining surface (guide surface)

[0052] Specify machining line or calculate machining line

[0053] The actual machining line is generated by considering factors such as layering, offset, and compensation.

[0054] By assembling the machining lines, a complete machining toolpath can be generated.

[0055] (The implementation varies slightly across platforms; for example, some platforms stitch the images together first and then perform offsetting and compensation.)

[0056] For the machining of side cutting edges with tilt angles and in conjunction with the toolpath generation process for side cutting edges, this invention optimizes the toolpath splicing process, as follows:

[0057] 1. A segmented toolpath structure is adopted, and toolpath splicing is achieved by inserting front and rear transition sections.

[0058] 2. Determine the tool axis direction by successive approximation.

[0059] When splicing toolpaths, the specific steps are as follows:

[0060] See Figure 2 The insertion of transition sections: To support the layered function of the toolpath and to take into account the tool compensation process, this invention designs each guide surface machining section as a three-section structure: a front transition section, a middle section, and a rear transition section.

[0061] The process of segmenting the toolpath is as follows:

[0062] Front transition section: The transition toolpath that connects to the previous guide surface, and is automatically inserted during splicing. It generally includes: inflection points, toolpath fillets, toolpath extension lines, and their combinations.

[0063] Post-transition section: The transition toolpath that connects to the next guide surface, automatically inserted during splicing. It generally includes: inflection points, toolpath fillets, toolpath extension lines, and their combinations.

[0064] Middle section: The actual processing line of the current guide surface, which will be cut off during splicing as needed.

[0065] See Figure 3 The spliced ​​toolpath is shown in the figure:

[0066] Tool path intersection: When the middle section of the tool path intersects, the middle section is cut off at the intersection point, and the intersection point (inflection point) is inserted as the transition section between the two tool paths.

[0067] Knife path extension: When the middle segments do not intersect, there are three scenarios:

[0068] 1) The extension line of the first segment intersects with the second segment;

[0069] 2) The extension line of the latter segment intersects with the former segment;

[0070] 3) The extension lines of the two cutter paths intersect.

[0071] For the first scenario: extend the first segment (middle segment) and find its intersection with the second segment (middle segment). If they intersect, insert an extension line after the first segment as a transition segment; simultaneously, truncate the second segment and insert an intersection point (inflection point) before it as a transition segment. The other two scenarios can be handled similarly; otherwise, there is no solution for the toolpath.

[0072] Tool path fillet: Based on the position where the spliced ​​machining line is tangent to the circle, cut off the machining line and insert an arc segment as a transition segment.

[0073] Calculate the transition section cutter position:

[0074] Without considering the effects of toolpath layering, offset, compensation, etc., the machining tool position point (tool head coordinates) of the middle section can be obtained directly from the machining line; for the transition section, the toolpath inflection point can be directly used as the machining point; the extension line or toolpath fillet can be obtained by discretization of the tool position point.

[0075] The tool axis direction in the transition section is calculated using successive approximation.

[0076] The direction of the cutter shaft in the middle section can be determined by the direction of the tangent of the guide surface (or the generatrix of the ruled surface). (If there is a side tilt angle, the cutter shaft can be rotated).

[0077] The tool axis of the transition section: The transition section is generally composed of inflection points, fillets, or extension lines. The extension line can be considered as the line connecting the end of the middle section to the inflection point, and the tool axis can be obtained by linear interpolation. The fillet tool axis must be aligned with the tool axis direction of the inflection point to ensure the continuity of the tool axis and the consistency of the layering. Therefore, once the tool axis direction at the inflection point is determined, the tool axis direction of the entire transition section can be calculated.

[0078] Considering that the toolpath may use a tapered end mill or have a side tilt angle, a successive approximation method is used to calculate the tool axis direction at the inflection point. The specific steps are as follows:

[0079] See Figure 4 Angle A: The angle between the cutter shaft and guide surface 1 (the tangent plane at the inflection point) (side tilt angle); Angle B: The angle between the cutter shaft and guide surface 2 (the tangent plane at the inflection point) (side tilt angle).

[0080] See Figures 5-8 At the inflection point, construct two conical surfaces, with the normal to the tangent plane of the guiding surface as their axis. The angles between the conical surfaces and the axis are (π / 2 - A) and (π / 2 - B), respectively. Let the angle between the normals of the two tangent planes be C. At this point:

[0081] 1) No solution (A+B+C>π): There is no solution when the two cones do not intersect.

[0082] 2) Simple root (A+B+C=π): When two cones are tangent, there is one and only one solution. The solution is the line of intersection of the cones.

[0083] 3) Two roots (A+B+C<π): When two cones intersect, there are two solutions, which are the lines of intersection of the cones.

[0084] See Figure 9 and Figure 10 Then, a successive approximation process is performed:

[0085] Using the constraints of these two tilt angles, we obtain the numerical solution for the tool axis direction by a stepwise approximation method.

[0086] Iteration initial value

[0087] Tool axis: Theoretically, the initial direction can be random. However, to speed up convergence, it is recommended to use the intersection of the tangent plane of guide surface 1 at that point and the tangent plane of guide surface 2 at that point, where both included angles are 0.

[0088] Angle α: The angle between the cutter axis and the tangent plane of guide surface 1 at that point;

[0089] Angle b: The angle between the cutter shaft and the tangent plane of the guide surface 2 at that point;

[0090] Iteration target

[0091] Angle a->Angle A;

[0092] Angle b -> Angle B;

[0093] Iterative process

[0094] One iteration consists of two steps:

[0095] first step

[0096] 1) Angle difference: Δa = included angle A – included angle a;

[0097] 2) Rotate the cutter shaft by an angle Δa, so that the angle between the cutter shaft and the tangent plane of the guide surface 1 is A;

[0098] Step 2

[0099] Angle difference: Δb = angle B – angle b;

[0100] Rotate the cutter shaft by an angle Δb, so that the angle between the cutter shaft and the tangent plane of the guide surface 2 is B.

[0101] Termination conditions:

[0102] Angle a = angle A, which holds true within the tolerance range;

[0103] Angle b = angle B, which holds true within the tolerance range.

[0104] The principle behind the above iterative process is as follows:

[0105] In one iteration, two rotations actually occur. Ignoring the initial iteration, the iteration process can be simplified as: rotating from cone 2 to cone 1, and then rotating back to cone 2. Therefore, after one iteration, the angle difference 2(Δb) is always 0. The iteration function at this point is:

[0106] Iteration function:

[0107] f(dir) = f(x, y, z) = Δa

[0108] The root of the function:

[0109] f(dir)=f(x,y,z)=Δa=0

[0110] See Figures 11 to 16 Here is a proof of convergence:

[0111] Iteration point definition:

[0112] Iteration point = cone vertex + iteration vector

[0113] Let the hypotenuses of the two cones both have a length of 1. If the iteration vector is normalized, the iteration point will always lie on the base of the cone. Therefore, each iteration can form an equilateral triangle, and the angle of the (vertices) is exactly the angle difference of the current iteration.

[0114] At this time, it exists that:

[0115]

[0116] Therefore, it is sufficient to prove that the length of the connection, dist, converges to 0.

[0117] Since Pt(i+1) is the closest point from Pt(i) to the cone surface, the distance is: see [reference needed]. Figure 13

[0118] Therefore, in each iteration (an iteration process is divided into two steps), the length of the connecting line is always decreasing, eventually converging to the closest point between the two cones; when the two cones intersect, they converge to 0.

[0119] The graph of the function dist is Figures 14-16 As shown.

[0120] illustrate:

[0121] The theoretical maximum value of dist is 2, which can be obtained if and only if the two cones are coaxial and opposite in direction, and the cone radius approaches 0.

[0122] When A+B+C<π has a local maximum, the iteration will get stuck in a loop (singularity). If the direction of the iteration happens to be on the plane of the axes of the two cones, it is necessary to actively break out of the loop.

[0123] While geometric intersection methods can also obtain the tool axis direction, in practice, it requires first constructing two conical surfaces and then performing the intersection operation, making its efficiency dependent on the underlying geometric kernel. Our method (the successive approximation method), however, uses purely mathematical methods, requiring only the calculation of the included angle and rotation vector in each iteration, resulting in low computational cost and high accuracy.

[0124] Initial value for tool axis iteration: Theoretically, the initial direction of the tool axis can be random, and it will eventually converge after multiple iterations. However, it is recommended to use the intersection direction of guide surface 1 (tangent plane) and guide surface 2 (tangent plane) as the initial value for iteration.

[0125] The relationship between the two roots (A+B+C<π) is that the two roots are mirror images of each other, and the mirror plane is the plane formed by the axes of the two cones.

[0126] Convergence speed: The convergence speed of this method is very fast in the early stage, but as it gradually approaches the root, the convergence speed decreases.

[0127] The segmented structure mentioned in this embodiment only refers to the three-segment structure; the segmented structure is not limited to three segments.

[0128] The successive approximation algorithm mentioned in this embodiment is essentially a process of iterating successively using the positional relationship between two conical surfaces to finally obtain the target solution. The successive approximation method in this article is actually an iterative method or a variation of the iterative method; therefore, methods with similar iterative forms between two conical surfaces are also included in this embodiment.

[0129] Example 2

[0130] This embodiment provides a computer device, such as a smartphone, tablet computer, laptop computer, desktop computer, rack server, blade server, tower server, or cabinet server (including standalone servers or server clusters composed of multiple servers) capable of executing programs. The computer device in this embodiment includes, but is not limited to, a memory and a processor that can be interconnected via a system bus.

[0131] In this embodiment, the memory (i.e., the readable storage medium) includes flash memory, hard disk, multimedia card, card-type memory (e.g., SD or DX memory), random access memory (RAM), static random access memory (SRAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), programmable read-only memory (PROM), magnetic memory, disk, optical disk, etc. In some embodiments, the memory can be an internal storage unit of a computer device, such as the hard disk or RAM of the computer device. In other embodiments, the memory can also be an external storage device of the computer device, such as a plug-in hard disk, smart media card (SMC), secure digital card (SD), flash card, etc., equipped on the computer device. Of course, the memory can also include both internal storage units and external storage devices of the computer device. In this embodiment, the memory is typically used to store the operating system and various application software installed on the computer device. In addition, the memory can also be used to temporarily store various types of data that have been output or will be output.

[0132] In some embodiments, the processor may be a central processing unit (CPU), a controller, a microcontroller, a microprocessor, or other data processing chip. The processor 22 is typically used to control the overall operation of a computer device. In this embodiment, the processor is used to run program code stored in memory or process data.

[0133] This embodiment also provides a computer-readable storage medium, such as flash memory, hard disk, multimedia card, card-type memory (e.g., SD or DX memory), random access memory (RAM), static random access memory (SRAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), programmable read-only memory (PROM), magnetic memory, disk, optical disk, server, App application store, etc., which stores computer programs, and the programs perform corresponding functions when executed by a processor.

[0134] Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, nor to combinations thereof. Those skilled in the art can make various changes, modifications, or combinations within the scope of the claims, which do not affect the essence of the present invention. Unless otherwise specified, the embodiments and features described in this application can be arbitrarily combined with each other.

Claims

1. A method for generating toolpaths for side milling with an angle, characterized in that, The specific steps are as follows: S1. Specify the current machining surface or guide surface. The guide surface is the target surface for side-edge machining and also the constraint surface for the machining toolpath. It consists of a set of connected surfaces. S2. User-specified or automatically generated original processing line; S3. Generate the actual machining line based on factors such as layering, offset, and compensation; S4. Insert a transition section into the actual machining line, determine the machining tool position point, and determine the tool axis direction; S5. Combine the toolpaths from step S4 to form the final five-axis side-edge machining toolpath; Step S4 includes step S44, which is as follows: S44. The successive approximation method is used to calculate the tool axis direction of the transition section: the tool axis of the intermediate section is determined by the direction of the generatrix of the tangent of the guide surface or the ruled surface corresponding to the intermediate section. If there is a side tilt angle, the tool axis is rotated. The tool axis of the transition section: The transition section consists of inflection points, fillets, or extension lines. The tool axis of the inflection points is obtained by a successive approximation method. The extension line is the line connecting the end of the middle section to the inflection point, and the tool axis is obtained by linear interpolation; the rounded corner tool axis and the tool axis of the inflection point are in the same direction to ensure the continuity of the tool axis and the consistency of the layering; Numerical solutions for the tool axis direction are obtained using a successive approximation method: where guide surface 1 and guide surface 2 are two adjacent guide surfaces at the inflection point, guide surface 1 is the guide surface on the side before the inflection point, and guide surface 2 is the guide surface on the side after the inflection point, and the inflection point is the inflection point position between guide surface 1 and guide surface 2; angle A is the target angle between the tool axis and the tangent plane of guide surface 1 at the inflection point, and angle B is the target angle between the tool axis and the tangent plane of guide surface 2 at the inflection point; Iteration initial value Cutter axis: The direction of the intersection of the tangent plane of guide surface 1 at the inflection point and the tangent plane of guide surface 2 at the inflection point, where the two included angles a and b are both 0; Angle a: The current angle between the cutter axis and the tangent plane of guide surface 1 at this inflection point; Angle b: The current angle between the cutter axis and the tangent plane of the guide surface 2 at this inflection point; Iteration target Angle a approaches angle A; Angle b approaches angle B; Iterative process One iteration consists of two steps: first step 1) Angle difference: Δa = Angle A - Angle a; 2) Rotate the cutter shaft by an angle Δa, so that the angle between the cutter shaft and the tangent plane of the guide surface 1 is A; Step 2 Angle difference: Δb = angle B - angle b; Rotate the cutter shaft by an angle Δb, so that the angle between the cutter shaft and the tangent plane of the guide surface 2 is B. Termination conditions: Angle a = angle A, which holds true within the tolerance range; Angle b = angle B, which holds true within the tolerance range.

2. The method for generating a side milling toolpath with an angle according to claim 1, characterized in that, Step S4 includes step S41, which is as follows: S41. Insert transition section: Divide each guide surface machining section into three sections, namely the front transition section, the middle section and the rear transition section.

3. The method for generating a side milling toolpath with an angle according to claim 2, characterized in that, Step S4 includes step S42, which is as follows: S42. Insert a transition segment to complete the splicing of the toolpaths, and perform corresponding processing on toolpath intersections, toolpath extensions, and toolpath fillets respectively.

4. The method for generating a side milling toolpath with an angle according to claim 3, characterized in that, Step S4 includes step S43, which is as follows: S43. Calculate the tool position point of the transition section: The tool position point of the intermediate section is the tool head coordinate, which is directly obtained from the machining line; for the transition section, the corner of the intersecting toolpath can be directly used as the tool position point; the tool position point of the extended toolpath or rounded toolpath can be obtained by discretization.

5. A computer device, the computer device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the program, it implements the steps of the method according to any one of claims 1 to 4.

6. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the program is executed by a processor, it implements the steps of the method according to any one of claims 1 to 4.

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