Cutter path and blank cutting volume calculation method based on point set representation

Abstract

The invention discloses a tool path and blank cutting volume calculation method based on point set representation, and the method converts a blank and a tool path into point sets, calculates the cutting volume through the intersection of the point sets, and simplifies the traditional geometric calculation. Meanwhile, the density of the point set can be flexibly adjusted, the calculation efficiency and precision of tool path optimization are improved, and dependence on an STL file and a third-party plug-in is avoided. The method is suitable for large-scale tool path optimization tasks, and the flexibility and controllability of the tool path optimization process can be improved.

Description

Technical Field

[0001] The present invention relates to the technical field of tool path optimization, and particularly relates to a method for calculating tool paths and blank cutting volumes based on point set representation. Background Art

[0002] Between the design of parts and the machining process on machine tools, it is necessary to utilize Powermill to provide perfect machining strategies to help users generate the best machining plans.

[0003] In the prior art, it is usually necessary to rely on third-party software such as ncbrain to optimize tool paths to ensure machining efficiency. These software need to process a large amount of geometric data during the optimization process and optimize tool paths by calculating cutting volumes. Although such tools are powerful, they have the following significant deficiencies:

[0004] High cost: Third-party software usually requires high licensing fees, and using them requires professional skills, which brings greater economic and technical burdens to small and medium-sized enterprises or individual users.

[0005] Lack of flexibility: Third-party software relies on specific geometric models and requires specific input and output interface support, which limits its application flexibility in different scenarios.

[0006] Therefore, there is an urgent need for a new tool path optimization method that can avoid using complex geometric models, improve calculation efficiency, and reduce dependence on third-party software. Summary of the Invention

[0007] In view of this, the present invention provides a method for calculating tool paths and blank cutting volumes based on point set representation, aiming to solve the problems mentioned in the background art.

[0008] To achieve the above object, the technical solution of the present invention is as follows:

[0009] A method for calculating tool paths and blank cutting volumes based on point set representation, characterized by including the following steps:

[0010] S1: Generate a point set of the blank, calculate the preliminary blank on the original workpiece using a virtual tool path, and represent each unit voxel with a point set, and adjust the density of the point set according to actual needs to balance calculation accuracy and efficiency;

[0011] S2: Convert the tool path into a point set, convert the tool path to be optimized into a set of point sets, and this point set accurately represents the cutting position of the tool to ensure that the cutting process can be accurately simulated;

[0012] S3: Calculate the cutting volume through point set intersection, compare the point sets of the blank and the tool path, screen out the cut voxels, and then calculate the cutting volume;

[0013] S4: Optimize the tool path. Based on the calculation result of the cutting volume, adjust the parameters of the tool path to achieve tool path optimization. According to actual requirements, multiple iterations can be performed until the optimization goal is met.

[0014] By adopting the above method, by converting the blank and the tool path into point sets and using the intersection between the point sets to calculate the cutting volume, the traditional geometric calculation is simplified and the dependence on third-party software is avoided.

[0015] Preferably: S4 specifically includes the following steps.

[0016] S4.1: Locally offset the original tool path upward according to the actual remaining state to ensure that the cutting material of each segment of the tool path is basically uniform.

[0017] S4.2: For the offset tool path, adjust the cutting speed of each segment of the tool path according to the actual removed volume of each segment of the tool path. When the cutting amount is large, reduce the cutting speed to avoid tool damage, and when the cutting amount is small, increase the cutting speed to improve the processing efficiency.

[0018] By adopting the above steps, the tool path can be effectively optimized and the processing efficiency can be improved.

[0019] Preferably: S4.2 specifically includes the following steps.

[0020] S4.21: Establish a tool library. According to the tool diameter and the material of the workpiece to be cut, define the best feed rate of each tool per unit cutting volume.

[0021] S4.22: Reconstruct the remaining model. Represent the remaining model in the form of point sets to avoid complex STL operations.

[0022] S4.23: Reconstruct the tool path trajectory. Represent the geometric shape formed in space after the tool moves along the tool path trajectory in the form of point sets.

[0023] S4.24: Boolean operation. Realize the Boolean intersection and Boolean difference set operations between the remaining model and the tool path trajectory.

[0024] By adopting the above steps, the tool path can be optimized and the processing efficiency can be improved.

[0025] Preferably: The blank is composed of multiple small cubes, and the tool path is also composed of multiple small cubes. By adopting the above structure, it is convenient to generate point sets and thus simplify the calculation.

[0026] Preferably: The sizes of the small cubes that make up the blank are the same as those of the small cubes that make up the tool path. By adopting the above structure, it can ensure the subsequent removal of the overlapping part and simplify the calculation.

[0027] Preferably, the sizes of the small cubes are adjustable. With the above structure, the calculation accuracy can be guaranteed.

[0028] Preferably, the method for calculating the volume in S3 is Boolean operation. By removing the space covered by the tool path point set from the blank point set, the removed points are obtained.

[0029] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0030] 1. By adopting the tool path and blank cutting volume calculation method based on point set representation provided by the present invention, by converting the blank and the tool path into point sets, the use of STL files and complex Boolean operations is avoided, reducing the calculation complexity and resource consumption.

[0031] 2. The density of the point set can be dynamically adjusted, the calculation accuracy can be flexibly controlled, and the calculation efficiency of tool path optimization can be effectively improved.

[0032] 3. This method can be used in combination with the development platform based on Powermill, without additional dependence on third-party software, increasing the controllability and flexibility of the tool path optimization process. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 is a flowchart of the tool path and blank cutting volume calculation method based on point set representation;

[0034] Figure 2 is a schematic structural diagram of the blank;

[0035] Figure 3 is a schematic structural diagram of the blank converted into a point set;

[0036] Figure 4 is a schematic diagram of the tool and the tool path;

[0037] Figure 5 is a schematic three-dimensional structural diagram generated during the tool movement process;

[0038] Figure 6 is Figure 5 a schematic structural diagram of being converted into a point set. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0039] The present invention will be further described below in conjunction with the embodiments and the drawings.

[0040] As Figures 1 to 6 shown, in this embodiment, a blank of 1000*1000*1000 (unit: millimeter) is taken as an example. The blank is composed of small cubes with a side length of 1 millimeter. It is set that the point at the lower left corner of each small cube represents this cube and is defined as a voxel. Through conversion, these small cubes are converted into a series of point sets in space.

[0041] In NC machining, the bottom - layer data of all tool paths are sets of points. Therefore, tool paths can be converted into a large number of straight - line segments. In this embodiment, taking a ball - end mill as an example, when the tool moves along these straight - line segments, it is actually like a ball sweeping in space, forming a cylinder with spherical ends. By dividing this cylinder into small cubes with a side length of 1 mm, during the division process, there will inevitably be some incomplete cubes. At this time, we fill or discard them according to the principle of rounding. Similarly, we set the point at the lower - left corner of each small cube to represent this cube, and then convert the tool - path into a set of points in space.

[0042] Since the sizes of the small cubes that make up the blank are the same as those of the small cubes that make up the tool path, through Boolean operations, duplicate points are removed, and these points are the actual volume to be cut.

[0043] Based on the calculated cutting volume, tool - path optimization can be carried out, which is specifically divided into the following two steps:

[0044] 1. Tool - path layering: The original tool path is locally offset upward according to the actual remaining state to ensure that the cutting material of each tool path is basically uniform. In Powermill, by converting the tool path into a reference line and using the upward - offset function of the reference - line tool path, the single - layer tool path is converted into a multi - layer tool path. In this way, some of the multi - layer tool paths obtained do not actually cut material, commonly known as "empty tool paths". In order to remove these empty tool paths, it is necessary to obtain the actual remaining state before each tool path cuts. In actual machining and programming, the tool path is a continuous process. The machining result of each tool path is actually the remaining model of the next tool path. Through the above steps, duplicate points have been removed, and the remaining points are the remaining model. Using the native function of Powermill, over - cutting inspection of the multi - layer tool path can be carried out through the remaining model, so as to trim the "empty tool paths" that do not cut material, and thus complete the tool - path layering.

[0045] 2. Feed optimization: For the offset tool path, according to the actual removed volume of each tool path, the cutting speed of each tool path is adjusted. When the cutting amount is large, the cutting speed is reduced to avoid tool damage, and when the cutting amount is small, the cutting speed is increased to improve the machining efficiency. Feed optimization specifically includes the following four steps.

[0046] 2.1 Tool - library establishment: According to the tool diameter and the material of the workpiece to be cut, the best feed rate (F: mm / min) per unit cutting volume is defined for each tool. Specifically, it can be referred to the following table.

[0047]

[0048] 2.2. Reconstruct the residual model: Represent the residual model in the form of a point set, avoiding complex STL operations.

[0049] 2.3. Reconstruct the tool path trajectory, representing the geometric shape formed in space after the tool moves along the tool path trajectory in the form of a point set.

[0050] 2.4. Boolean operation, implementing the Boolean intersection and Boolean difference operations between the residual model and the tool path trajectory.

[0051] In the Boolean operation of the point set, since the points are evenly distributed in the space coordinate system, by setting a unified voxel size, it can be ensured that the point set of the blank and the point set of the tool path cutting path have the same accuracy. This means that the blank and the tool path have the same point density on the same coordinate grid, avoiding mismatches between different precisions.

[0052] Therefore, the Boolean operation can be simplified by removing duplicates: when the point set of the blank coincides with the point set of the tool path cutting path, it is considered that the point has been cut, and then removed from the blank. This method not only improves the operation efficiency but also avoids the complex geometric calculations commonly found in traditional Boolean operations.

[0053] Specifically, it is to remove the space covered by the tool path point set from the blank point set to obtain the part cut by the tool. These removed points are the cut volume.

[0054] In the space represented by the point set, due to calculation accuracy, multiple points at the same position may coincide. Even if the points of the tool and the blank coincide in some areas, these points represent the actual cutting areas in the space.

[0055] During the Boolean operation, if the tool point set and the blank point set coincide in some areas, it means that the tool has cut the material in that area. Even if there are duplicate points, these points need to be regarded as valid data during the Boolean operation and participate in the final cutting volume calculation.

[0056] Of course, to avoid unnecessary computational effort, during actual operation, the system will remove duplicates for points at the same position. Although multiple tool path trajectories may form coincident points at the same position, these duplicate points will not be counted multiple times in the cutting volume calculation.

[0057] The final cutting volume calculation is based on the non-duplicate point set. After calculating the Boolean operation, the remaining point set represents the cutting volume.

[0058] In this embodiment, the side length of the small cube is not limited to an integer. At the same time, during the actual operation process, the side length of the small cube can be changed to optimize the accuracy.

[0059] Finally, it should be noted that the above description is only the preferred embodiment of the present invention. Under the inspiration of the present invention, those of ordinary skill in the art can make various similar representations without violating the purpose and claims of the present invention. Such transformations all fall within the protection scope of the present invention.

Claims

1. A method for calculating tool path and blank cutting volume based on point set representation, characterized in that, It includes the following steps: S1: Generate a point set of the blank. Calculate the preliminary blank on the original workpiece using a virtual tool path, and represent each unit voxel with a point set. Adjust the density of the point set according to actual requirements to balance calculation accuracy and efficiency; S2: Convert the tool path into a point set. Convert the tool path to be optimized into a set of point sets, which accurately represent the cutting positions of the tool, ensuring that the cutting process can be accurately simulated; S3: Calculate the cutting volume. Compare the point sets of the blank and the tool path, filter out the cut voxels, and then calculate the cutting volume; S4: Optimize the tool path. Based on the calculation results of the cutting volume, adjust the parameters of the tool path to achieve tool path optimization. According to actual requirements, multiple iterations can be performed until the optimization goal is met.

2. The method for calculating the cutting volume of the tool path and the blank based on the point set representation according to claim 1, wherein Specifically, S4 includes the following steps: S4.1: Locally offset the original tool path upward according to the actual remaining state to ensure that the cutting material of each tool path is basically uniform; S4.2: For the offset tool path, adjust the cutting speed of each tool path according to the actual removed volume of each tool path. Reduce the cutting speed when the cutting amount is large to avoid tool damage, and increase the cutting speed when the cutting amount is small to improve machining efficiency.

3. The method for calculating the cutting volume of a tool path and a blank based on point set representation according to claim 2, wherein Specifically, S4.2 includes the following steps: S4.21: Establish a tool library. Define the best feed rate per unit cutting volume for each tool according to the tool diameter and the material of the workpiece to be cut; S4.22: Reconstruct the remaining model. Represent the remaining model in the form of a point set, avoiding complex STL operations; S4.23: Reconstruct the tool path trajectory. Represent the geometric shape formed in space after the tool moves along the tool path trajectory with a point set; S4.24: Boolean operation. Implement the Boolean intersection and Boolean difference set operations between the remaining model and the tool path trajectory.

4. The method for calculating the cutting volume of the tool path and the blank based on the point set representation according to claim 3, wherein, The blank is composed of multiple small cubes, and the tool path is also composed of multiple small cubes.

5. The method for calculating the cutting volume of a tool path and a blank based on point set representation according to claim 4, wherein: The sizes of the small cubes that make up the blank are the same as those of the small cubes that make up the tool path.

6. The method for calculating the tool path and the blank cutting volume based on the point set representation according to claim 5, wherein: The sizes of the respective small cubes are adjustable.

7. The method for calculating the cutting volume of the tool path and the blank based on the point set representation according to claim 3, wherein: The method for calculating the volume in S3 is Boolean operation. By removing the space covered by the tool path point set from the blank point set, the removed points are obtained.

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