Method and equipment for generating side milling machining tool path with inclination angle and storage medium

Abstract

The invention relates to the technical field of side edge machining, in particular to a method and equipment for generating a side milling machining tool path with an inclination angle and a storage medium. Compared with the prior art, the technical scheme provided by the invention has the following beneficial effects that a sectional type tool path structure is utilized, tool path splicing is realized by inserting a transition section tool path, and a machining tool location point is obtained; and iterating the cutter axis direction back and forth between the two conical surfaces by using a successive approximation method to finally obtain an intersection line of the two conical surfaces, and taking the intersection line as the cutter axis direction of the inflection point position of the cutter path.

Description

Technical Field

[0001] The present invention relates to the technical field of side edge processing, and in particular to a method, device and storage medium for generating a side milling tool path with an inclination angle. Background Art

[0002] Side edge machining is an efficient and practical method for surface machining. However, for complex surface types such as non-ruled surfaces or non-developable ruled surfaces, side edge machining tool paths cannot be used for machining. In this case, a side edge machining tool path can be assigned a side tilt angle, and the side edge machining can be changed to point milling to achieve high-precision machining of complex surfaces. During the side edge machining process, a side edge angle will also be assigned to the tool path to avoid tool collision in consideration of tool avoidance. In addition, the tapered milling cutter in the side edge machining naturally has a fixed angle with the guide surface. The existence of the side tilt angle will affect the surface machining accuracy at the corner position. If it is not properly handled, it will cause overcutting or undercutting.

[0003] When machining non-straight surfaces or considering tool avoidance factors, a tilt angle is added to the side edge tool path. For a single guide surface, to add a tilt angle to the tool path, you only need to add an additional angle to the tool axis; but for connected guide surfaces, the direction of the tool axis at the corner position is generally difficult to determine. The common method is to leave a certain machining allowance at the corner position and then perform root / corner cleaning. If you want to obtain an accurate solution, the geometric intersection method is generally used to construct a cone surface at the corner position, obtain the cone surface intersection line through geometric intersection, and use the intersection line direction as the tool axis direction. This method relies on the geometric kernel, and the intermediate process involves modeling and intersection operations. Summary of the invention

[0004] The purpose of the present invention is to solve the deficiencies of the prior art, propose an algorithm for quickly determining the tool axis direction at a corner position based on numerical calculation, and apply this algorithm in the generation of side edge tool paths.

[0005] To achieve the above object, the present invention provides a method for generating a side milling tool path with an inclination angle, and the specific steps are as follows:

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

[0007] S2. Original processing line specified by the user or automatically generated;

[0008] S3. Generate the actual processing line for the factors of layering, offset and compensation;

[0009] S4. inserting a transition section into the actual processing line, determining the processing tool position point, and using the successive approximation method to determine the tool axis direction;

[0010] S5. Connect the tool paths in step S4 to form a final five-axis side edge machining tool path.

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

[0012] S41. Insert transition section: divide each guide surface processing section into three sections, namely, a front transition section, a middle section and a rear transition section.

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

[0014] S42. Insert the transition section to complete the splicing of the tool paths, and perform corresponding processing on the tool path intersection, tool path extension and tool path rounding.

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

[0016] S43. Calculate the tool position point of the transition section: the processing tool position point of the middle section is the tool head coordinate, which is directly obtained from the processing line; for the transition section, the corner of the cross tool path can be directly used as the processing tool position point; the tool position point of the extended tool path or the rounded tool path can be obtained by discretization.

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

[0018] S44. Calculate the direction of the cutter axis in the transition section by using the stepwise approximation method: the cutter axis in the middle section is determined by the direction of the current tangent line of the guide surface or the generatrix of the ruled surface. If there is a side tilt angle, the cutter axis is rotated;

[0019] Tool axis of transition section: The transition section is composed 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 and the inflection point, and the tool axis is obtained by linear interpolation. The tool axis of the fillet is consistent with the tool axis direction 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, which includes a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the steps of the above method when executing the program.

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

[0022] Compared with the prior art, the technical solution proposed in the present application has the following beneficial effects: utilizing a segmented tool path structure, tool path splicing is achieved by inserting a transition segment tool path, and a processing tool position point is obtained; utilizing a stepwise approximation method, the tool axis direction is iterated back and forth between the 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 turning point of the tool path. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0024] Figure 1 It is a schematic diagram of the tool path flow for side edge processing of the present invention;

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

[0026] Figure 3 It is a schematic diagram of the tool path structure after splicing of the present invention;

[0027] Figure 4 It is a schematic diagram of the knife axis direction and the inclination angle at the inflection point of the present invention;

[0028] Figure 5 It is a schematic diagram of the geometric constraint relationship of the roll angle of the present invention;

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

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

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

[0032] Fig. 9 It is a schematic diagram of successive approximation of the present invention;

[0033] Fig.10 It is an iterative flow chart of the present invention;

[0034] Fig.11 It is an iterative schematic diagram of the present invention;

[0035] Fig.12 It is a schematic diagram of angle difference and iteration point of the present invention;

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

[0037] Fig.14is the rootless function image of the present invention (A+B+C>π);

[0038] Fig.15 is the single root function image of the present invention (A+B+C=π);

[0039] Fig.16 It is the double root function image (A+B+C<π) of the present invention. DETAILED DESCRIPTION

[0040] The following will clearly and completely describe and discuss the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings of the present invention. Obviously, what is described here is only a part of the examples of the present invention, not all the examples. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0041] It should be noted that when a component is referred to as being "fixed to" another component, it may be directly on the other component or there may also be a component centered. When a component is considered to be "connected to" another component, it may be directly connected to the other component or there may also be a component centered. When a component is considered to be "set on" another component, it may be directly set on the other component or there may also be a component centered. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only.

[0042] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0043] Example 1

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

[0045] Side edge milling: Using the side edge of the tool as the cutting edge to process along the curved surface can obtain a smoother surface processing quality. It is an efficient and high-precision surface processing method, especially suitable for the finishing process of complex curved surfaces.

[0046] Guide surface: The target surface for side edge machining, and also the constraint surface of the machining tool path. Generally speaking, the guide surface is composed of a group of connected surfaces.

[0047] Rake angle: the angle between the tool axis and the guide surface. In side edge processing, the rake angle can be used with an appropriate tool head to transform side edge processing into spot milling, which is used to process some non-straight surfaces or non-developable straight surfaces; sometimes the rake angle is actively added to the tool path to avoid collision.

[0048] Conical milling cutter: Conical milling cutter occupies an important position in the metal processing industry with its versatility, low cost, high efficiency and high-quality processing capabilities. Its wide range of applications and reliable performance make it an indispensable tool in the manufacturing and processing fields. Compared with ordinary milling cutters, conical milling cutters naturally have a fixed angle with the guide surface.

[0049] Tool position point: The so-called tool position point refers to the point used to indicate the tool characteristics when programming and processing. It is also the reference point for tool setting and processing. For various end mills, the intersection of the tool axis and the bottom of the tool is generally taken; for turning tools, it is taken as the tool tip; for drill bits, it is taken as the drill tip.

[0050] See also Figure 1 , this embodiment provides a method for generating a side milling tool path with an inclination angle:

[0051] Specify machining surface (guide surface)

[0052] Specify processing line or calculate processing line

[0053] Generate actual processing lines taking into account factors such as layering, offset, compensation, etc.

[0054] Splice processing lines to generate complete processing toolpaths

[0055] (The implementation varies slightly on each platform, for example, some platforms first splice and then perform offset and compensation.)

[0056] Aiming at the side edge machining process with an inclination angle and combining the side edge machining tool path generation process, the present invention optimizes the tool path splicing process, and the specific methods are as follows:

[0057] 1. Use segmented tool path structure to achieve tool path splicing by inserting front and rear transition sections

[0058] 2. Use successive approximation to determine the direction of the tool axis

[0059] When splicing tool paths, the details are as follows:

[0060] See also Figure 2 , inserting transition section: to support the layering function of tool path and taking into account the tool compensation process. The present invention designs each guide surface processing section into three sections, namely: front transition section, middle section and rear transition section.

[0061] The segmentation process of the tool path is as follows:

[0062] Front transition section: The transition tool path connected to the previous guide surface, which is automatically inserted during splicing. Generally includes: inflection point, tool path fillet, tool path extension line and their combination.

[0063] Rear transition section: The transition tool path connected to the next guide surface will be automatically inserted during splicing. Generally includes: inflection point, tool path fillet, tool path extension line and their combination.

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

[0065] See also Figure 3 , the tool path after splicing 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, and the intersection (inflection point) is inserted as the front and back transition section between the two tool paths.

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

[0068] 1) The extension line of the previous section intersects with the next section;

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

[0070] 3) The extension lines of the front and rear tool paths intersect.

[0071] For the first scenario: extend the front section of the tool path (middle section) and intersect it with the back section of the tool path (middle section). If they intersect, insert an extension line after the front section of the tool path as the back transition section of the front section; at the same time, cut off the back section of the tool path, and insert an intersection point (inflection point) before the back section of the tool path as the front transition section of the back section of the tool path. The other two situations can be handled similarly, and there is no solution for other tool paths.

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

[0073] Calculate the transition section tool position:

[0074] Without considering the influence of tool path layering, offset, compensation and other factors, the machining tool position point (tool head coordinates) of the middle section can be obtained directly by machining the line; for the transition section, the tool path turning point can be directly used as the machining point; the extension line or tool path fillet can be obtained by discretization to obtain the tool position point.

[0075] Calculating the tool axis direction in the transition section using stepwise approximation

[0076] The knife axis of the middle section can be determined by the direction of the tangent line of the guide surface (or the generatrix of the ruled surface) (if there is a tilt angle, the knife axis can be rotated).

[0077] Tool axis of transition section: The transition section is generally composed of an inflection point, a fillet, or an extension line. The extension line can be regarded as the line from the end of the middle section to the inflection point, and the tool axis can be obtained by linear interpolation; the tool axis of the fillet must be consistent with the tool axis direction of the inflection point to ensure the continuity of the tool axis and the consistency of the layering. Therefore, as long as the tool axis direction of the inflection point is determined, the tool axis direction of the entire transition section can be calculated.

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

[0079] See also Figure 4 : Angle A: the angle (roll angle) between the tool axis and the guide surface 1 (the tangent plane at the inflection point); Angle B: the angle (roll angle) between the tool axis and the guide surface 2 (the tangent plane at the inflection point).

[0080] See also Figure 5-Figure 8 : Make two cones at the inflection point, with the cones taking the normal of the tangent plane of the guide surface as the axis, and the angles between the cones and the axis are (π / 2-A) and (π / 2-B) respectively. Let C be the angle between the two tangent plane normals, then:

[0081] 1) No solution (A+B+C>π): When the two cones do not intersect, there is no solution;

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

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

[0084] See also Fig. 9 and Fig.10 , followed by successive approximation:

[0085] Using the constraints of these two roll angles, we use the successive approximation method to obtain the numerical solution of the tool axis direction.

[0086] Iteration initial value

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

[0088] Angle a: the angle between the tool axis and the tangent plane of the guide surface 1 at this point;

[0089] Angle b: the angle between the tool axis and the tangent plane of the guide surface 2 at this point;

[0090] Iteration Target

[0091] Angle a->Angle A;

[0092] Angle b -> Angle B;

[0093] Iterative process

[0094] One iteration is divided into two steps:

[0095] first step

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

[0097] 2) Rotate the knife axis by an angle Δa, so that the included angle between the knife axis 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 knife axis by an angle of Δb so that the included angle between the knife axis and the tangent plane of the guide surface 2 is B;

[0101] Termination conditions:

[0102] Angle a = Angle A, which is within the tolerance range;

[0103] Angle b = angle B, which is valid within the tolerance range.

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

[0105] In one iteration, two rotations are actually performed. If the first iteration is not considered, 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. At this time, the iteration function 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 also Figures 11 to 16 , to prove the convergence:

[0111] Iteration point definition:

[0112] Iteration point = cone vertex + iteration vector

[0113] Assume that the length of the hypotenuse of the two cones is 1. At this time, as long as the iteration vector is normalized, the iteration point must be located on the base of the cone. Therefore, each iteration process can form an equilateral triangle, and the (vertex) angle is exactly the angle difference of the current iteration.

[0114] At this time there are:

[0115]

[0116] So we just need to prove that the line length dist converges to 0.

[0117] And because: Pt(i+1) is the closest point on the cone from Pt(i), so the distance: see Fig.13

[0118] Therefore, in each iteration (one iteration process is divided into two steps), the length of the iterative connection line is always shrinking, and finally converges to the nearest point of the two cone surfaces; when the two cone surfaces intersect, they converge to 0.

[0119] The function graph of dist is Figure 14-16 shown.

[0120] illustrate:

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

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

[0123] Although the geometric intersection method can also obtain the tool axis direction, in actual use, it is necessary to first construct two cone surfaces and then perform the intersection operation. The efficiency depends on the underlying geometric kernel. This method (progressive approximation method) purely uses mathematical methods. Each iteration only needs to calculate the angle and rotation vector, which has a small amount of calculation and high accuracy.

[0124] Initial value of tool axis iteration: In theory, 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 the guide surface 1 (cutting plane) and the guide surface 2 (cutting plane) as the initial value of the iteration.

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

[0126] Convergence speed: This method converges very quickly in the initial stage, but as it gradually approaches the root, the convergence speed here is also decreasing.

[0127] The segmented structure mentioned in this embodiment only mentions a three-segment structure, and the segmented structure is not limited to three segments.

[0128] The essence of the successive approximation algorithm mentioned in this embodiment is to use the positional relationship between the two cones, iterate successively, and finally obtain the target solution. The successive approximation method in this article is actually an iterative method or a variation of an iterative method; therefore, methods with similar iterative forms between two cones are also included in this embodiment.

[0129] Example 2

[0130] The present embodiment provides a computer device, such as a smart phone, tablet computer, laptop computer, desktop computer, rack server, blade server, tower server or cabinet server (including an independent server or a server cluster composed of multiple servers) that can execute programs. The computer device of the present embodiment includes at least but is not limited to: a memory and a processor that can communicate with each other through a system bus.

[0131] In this embodiment, the memory (i.e., readable storage medium) includes flash memory, hard disk, multimedia card, card-type memory (e.g., SD or DX memory, etc.), 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, magnetic disk, optical disk, etc. In some embodiments, the memory may be an internal storage unit of a computer device, such as a hard disk or memory of the computer device. In other embodiments, the memory may also be an external storage device of a computer device, such as a plug-in hard disk, a smart memory card (Smart Media Card, SMC), a secure digital (Secure Digital, SD) card, a flash card (Flash Card), etc. equipped on the computer device. Of course, the memory may also include both the internal storage unit of the computer device and its external storage device. In this embodiment, the memory is generally used to store the operating system and various application software installed on the computer device. In addition, the memory may also be used to temporarily store various types of data that have been output or are to be output.

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

[0133] This embodiment also provides a computer-readable storage medium, such as a flash memory, a hard disk, a multimedia card, a card-type memory (for example, an SD or DX memory, etc.), a random access memory (RAM), a static random access memory (SRAM), a read-only memory (ROM), an electrically erasable programmable read-only memory (EEPROM), a programmable read-only memory (PROM), a magnetic memory, a disk, an optical disk, a server, an App application store, etc., on which a computer program is stored, and the corresponding function is realized when the program is executed by a processor.

[0134] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and one or more of the above embodiments are combined into one embodiment. Those skilled in the art can make various changes or modifications or combinations within the scope of the claims, which does not affect the essence of the present invention. In the absence of conflict, the embodiments of the present application and the features in the embodiments can be combined with each other at will.

Claims

1. A method for generating a side milling tool path with an inclination angle, characterized in that: The specific steps are as follows: S1. Specify the current machining surface or guide surface; S2. Original processing line specified by the user or automatically generated; S3. Generate the actual processing line for the factors of layering, offset and compensation; S4. inserting a transition section into the actual processing line, determining the processing tool position point, and using the successive approximation method to determine the tool axis direction; S5. Connect the tool paths in step S4 to form a final five-axis side edge machining tool path.

2. The method for generating a tool path for side milling with an inclination angle according to claim 1, characterized in that: The step S4 includes step S41, and the step S41 is specifically as follows: S41. Insert transition section: divide each guide surface processing section into three sections, namely, a front transition section, a middle section and a rear transition section.

3. The method for generating a tool path for side milling with an inclination angle according to claim 2, characterized in that: The step S4 includes step S42, and the step S42 is specifically as follows: S42. Insert the transition section to complete the splicing of the tool paths, and perform corresponding processing on the tool path intersection, tool path extension and tool path rounding.

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

5. The method for generating a tool path for side milling with an inclination angle according to claim 4, characterized in that: The step S4 includes step S44, and the step S44 is specifically as follows: S44. Calculate the direction of the cutter axis in the transition section by using the stepwise approximation method: the cutter axis in the middle section is determined by the direction of the current tangent line of the guide surface or the generatrix of the ruled surface. If there is a side tilt angle, the cutter axis is rotated; Tool axis of transition section: The transition section is composed of inflection points, fillets or extension lines, and the tool axis of the inflection point is obtained by successive approximation method; The extension line is the line connecting the end of the middle segment and the inflection point, and the tool axis is obtained by linear interpolation; the fillet tool axis is consistent with the tool axis direction 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 segment is calculated.

6. A 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, the steps of the method according to any one of claims 1 to 5 are implemented.

7. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the program is executed by a processor, the steps of the method according to any one of claims 1 to 5 are implemented.

Images