Self-adaptive tool path planning method for complex curved surface mold machining

Abstract

The invention provides a self-adaptive tool path planning method for complex curved surface mold machining, and relates to the technical field of mold machining. Comprising the following steps: step 1, carrying out pre-modeling analysis on a mold, according to the shape of a complex curved surface of a predetermined mold, constructing a pre-cutting feature of the predetermined mold by adopting a basic graph splicing mode, recording the splicing and combining process of each basic graph of the pre-cutting feature, and carrying out reverse combination, in the process, the distance between the contour range of the pre-cutting feature and the complex curved surface of the preset mold is controlled to be 0.1-0.3 mm; the method comprises the following steps of 1, tool path shape pre-combination analysis, 2, tool path shape pre-combination analysis, 3, complex curved surface mold modeling and 4, milling speed control. According to the method, the basic graph is subjected to pre-modeling in the mode that the coincidence range is smaller than 10%, the machining speed of the regular basic graph can be reflected through the reverse combination process, the machining efficiency is improved, meanwhile, the follow-up grinding time can be shortened, the middle vacant area is sawed away, and the situation that the machining track is too long is avoided.

Description

Technical Field

[0001] The invention relates to the technical field of mold processing, and in particular to an adaptive tool path planning method for complex curved surface mold processing. Background Art

[0002] Molds are tools used for molding and blanking in industrial production, and are known as the "mother of industry". Molds play an extremely important role in the manufacturing industry. They achieve the processing of the appearance of objects by changing the physical state of the molded materials. They are commonly used in the processing of plastic products. The mold itself has a certain degree of precision, especially when it comes to complex curved surfaces. Usually, it requires complicated programming and then CNC milling equipment for processing, followed by grinding, heat treatment, coating and other processes to produce finished products.

[0003] In the process of processing molds, CNC milling equipment in the prior art usually uses the dimensions corresponding to the complex curved surfaces of the mold for programming after modeling to enable the CNC milling equipment to perform processing. However, due to the difficulty of surface processing, the programming process usually takes a lot of time, and the complex shape also affects the processing time. Summary of the invention

[0004] 1. Technical issues to be solved

[0005] In view of the deficiencies in the prior art, the present invention provides an adaptive tool path planning method for complex curved surface mold processing, which solves the problem of slow programming and prolonged processing time when the existing CNC milling equipment processes complex curved surfaces.

[0006] (II) Technical solution

[0007] To achieve the above objectives, the present invention is implemented through the following technical solutions: an adaptive tool path planning method for complex curved surface mold processing, comprising the following steps:

[0008] Step 1: Mold pre-modeling analysis

[0009] According to the shape of the complex curved surface of the predetermined mold, the predetermined mold pre-cut features are constructed by splicing basic graphics, and the splicing and combination process of each basic graphic of the pre-cut features is recorded and reversely combined. During the process, the contour range of the pre-cut features and the spacing between the complex curved surface of the predetermined mold are controlled to be 0.1-0.3mm;

[0010] Step 2: Pre-combination analysis of tool path shape

[0011] According to the reverse combination of the basic graphics of the pre-cut features and the processing shapes of a single CNC milling tool, the features are compared, and the tool pre-cutting range is obtained by the method of minimum overlap area and the pre-cutting path with the fastest processing speed of each corresponding basic graphic is recorded;

[0012] Step 3: Complex surface mold modeling

[0013] On the basis of step 1, a model of a complex curved surface mold is constructed, and shape coordinate parameters of the curved surface are obtained. Then, the coincidence point of the pre-cut path and the shape coordinate parameters is obtained as the starting point of the next milling process and the machining tool path is regenerated.

[0014] Step 4: Milling speed control

[0015] According to the overlapping points obtained in step three, the gradient thickness range is obtained in combination with the position range distributed in the corresponding basic figure, and the milling speed is controlled in a manner that the distance gradient decreases and the speed increases according to the horizontal spacing of the gradient thickness range and the shape coordinate parameters, and the flow rate of the cutting fluid is controlled according to the milling speed.

[0016] Preferably, in the step 1, if the distance between the contour range of the basic figure of the pre-cut feature combination and the complex curved surface is greater than 0.1-0.3 mm, the corresponding local part is modeled in detail using parameterization.

[0017] Preferably, in the step 2, the reverse combination of the basic graphics and the area left in the middle of the pre-cut path are processed by first retaining and then sawing.

[0018] Preferably, in step three, the pre-cut path restores the processing process of the complex curved surface mold according to the reverse combination of the basic graphics splicing, and adopts a layer-by-layer cutting method from top to bottom.

[0019] Preferably, the path generated in the process of regenerating the machining tool path by the pre-cutting path is continuous. If the included overlapping point is within the range of the milling basic figure, the process continues to be completed. After the machining is completed, the tool is returned to the corresponding overlapping point and the tool is moved again for machining. The above-mentioned tool moving path is the straight-line distance from the next basic figure to the overlapping point.

[0020] Preferably, the straight-line distance is locally bent according to the moving angular range of the milling tool to avoid tool collision.

[0021] Preferably, the free range from the cutting range corresponding to the machining tool path to the shape coordinate parameters is defined as the grinding range, and parametric grinding is performed.

[0022] (III) Beneficial effects

[0023] The invention provides an adaptive tool path planning method for complex curved surface mold processing.

[0024] It has the following beneficial effects:

[0025] 1. In the present invention, by using the basic graphics with an overlap range of less than 10% for pre-modeling, the processing speed of the regular basic graphics can be reflected through the reverse combination process, which can effectively improve the processing efficiency and reduce the subsequent grinding time. The empty area in the middle is sawed off to avoid the processing track being too long.

[0026] 2. In the present invention, by controlling the contour range of the pre-cut feature and the spacing between the complex curved surface of the predetermined mold to be 0.1-0.3 mm, it is convenient for the subsequent generation of processing trajectories to avoid tool collision or extend unnecessary corner adjustment length. In addition, it can also ensure that the subsequent grinding process can grind out complex curved surfaces that meet the surface accuracy.

[0027] 3. In the present invention, by obtaining a gradient thickness range according to the position range of the basic figure corresponding to the overlapping point, the milling speed and the flow rate of the cutting fluid are controlled accordingly, thereby preventing the occurrence of milling defects caused by local overheating due to excessive cutting speed. DETAILED DESCRIPTION

[0028] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] Embodiment 1:

[0030] An embodiment of the present invention provides an adaptive tool path planning method for complex curved surface mold processing, comprising the following steps:

[0031] Step 1: Mold pre-modeling analysis

[0032] According to the shape of the complex curved surface of the predetermined mold, the pre-cut features of the predetermined mold are constructed by splicing basic graphics, and the splicing and combination process of each basic graphic of the pre-cut features is recorded and reversely combined. In the process, the contour range of the pre-cut features and the spacing between the complex curved surface of the predetermined mold are controlled to be 0.1-0.3mm. The basic graphics used in the above process include cuboids, cubes, ellipsoids, spheres, cylinders, cones, and tables. By controlling the volume range of the basic graphics, the overlap area and the unevenness of the smaller outer edges are minimized, and the unit volume is controlled to be greater than 5 cubic meters. Square millimeters, to avoid basic graphics that are too small to be conducive to later cutting, in the above process, the volume range overlap of each basic graphic is controlled to be less than 10%, the above basic graphic splicing and combination process is the process of splicing and combining each basic graphic into a complex curved surface shape, and the corresponding reverse combination process is the top-down layer-by-layer removal process of each basic graphic splicing, which is used to simulate the milling removal process. In the above, by controlling the contour range of the pre-cut feature of 0.1-0.3mm and the complex curved surface spacing of the predetermined mold, it is convenient for the turning of the milling band saw, that is, to ensure the continuity of the trajectory;

[0033] Step 2: Pre-combination analysis of tool path shape

[0034] According to the reverse combination of the basic graphics of the pre-cut features, the features are compared with the processing shapes of a single CNC milling tool, and the tool pre-cutting range is obtained by the method of minimum overlap area, and the pre-cutting path of the fastest processing speed of each corresponding basic graphics is recorded. The processing shapes of the above-mentioned single CNC milling tool refer to the shapes that can be processed by the milling tool. In order to facilitate this step, the similar basic graphics selected according to the processing shapes of the single CNC milling tool in step one can be adjusted and then spliced, which is convenient for generating the processing tool path in step three, which is conducive to reducing the amount of calculation and improving the generation speed;

[0035] Step 3: Complex surface mold modeling

[0036] On the basis of step 1, a model of a complex curved surface mold is constructed, and the shape coordinate parameters of the curved surface are obtained. Then, the coincidence point of the pre-cut path and the shape coordinate parameters is obtained as the starting point of the next milling process and the machining tool path is regenerated. The pre-cut path restores the machining process of the complex curved surface mold based on the reverse combination of the basic graphics splicing, and adopts a layer-by-layer cutting method from top to bottom. The coincidence point is defined as the starting point of the next milling process because it is convenient for positioning. Although the coincidence point is not necessarily the end point of the previous milling process, if multiple coincidence points are obtained in the same milling process, the coincidence point at the end of the machining path is used first, so as to reduce the processing time of the current basic graphics. The movement range from the first basic figure to the next basic figure is not adopted in order to facilitate the replacement of the milling tool or the turning and movement of the milling tool. The coincidence point is highlighted in the modeling process and marked with different colors from top to bottom. It is preferred to use gradually darker colors according to the downward depth from top to bottom to facilitate differentiation. In the process of CNC milling, the position of the coincidence point is measured by the dimension measuring equipment to determine whether there is a processing deviation. If the dimension coordinate position of the coincidence point based on any external contour angle of the mold changes, it means that the mold position of the processing is offset and needs to be adjusted.

[0037] Step 4: Milling speed control

[0038] According to the overlapping points obtained in step three, and in combination with the position range distributed in the corresponding basic figure, the gradient thickness range is obtained, and the milling speed is controlled in a manner that the distance gradient decreases and the speed increases according to the gradient thickness range and the horizontal spacing of the coordinates of the shape coordinate parameters. The flow rate of the cutting fluid is controlled according to the milling speed. The above-mentioned gradient thickness range is similar to the operation of solid slicing, which is convenient for distance positioning. At the same time, since the mold is first three-dimensionally modeled and then milled, the process is made more intuitive and visible through the gradient thickness range method, and the corresponding milling speed change will also correspond to the change in the temperature of the mold. In this case, controlling the flow rate of the cutting fluid can minimize the thermal deformation of the mold and greatly reduce the processing error. At the same time, the processed surface will not harden due to excessive temperature, which is of obvious significance for molds using high hardness materials.

[0039] In step one, if the distance between the contour range of the basic figure of the pre-cut feature combination and the complex surface is greater than 0.1-0.3mm, the corresponding local part will be modeled in detail using parametric modeling. By using parametric detailed modeling locally, the complexity of step three can be reduced, and it is also convenient to maximize the fit of the various processing shapes of the CNC milling tool. After the parametric detailed modeling of the local part, it is also convenient to replace the new basic figure.

[0040] In step 2, the reverse combination of the basic graphics and the empty area in the middle of the pre-cut path are processed by first retaining and then sawing off. The sawing method can increase the processing speed. The basic graphics can also be spliced ​​according to the shape of the complex curved surface of the predetermined mold, and processed layer by layer by gradual milling and horizontal sawing, so as to reduce the wear of the milling tool.

[0041] The path generated in the process of regenerating the machining tool path by the pre-cutting path is continuous. If the included coincidence point is within the range of the milling basic figure, it will continue to be completed. After the machining is completed, the tool will return to the corresponding coincidence point and move the tool again for machining. The above-mentioned tool moving path is the straight-line distance from the next basic figure to the coincidence point.

[0042] The straight line distance is adjusted according to the moving angle range of the milling tool to avoid tool collision.

[0043] The free range from the cutting range corresponding to the machining tool path to the shape coordinate parameters is defined as the grinding range, and parametric grinding is performed. Since the contour range of the pre-cut feature and the distance between the complex surface of the predetermined mold are controlled in advance to be 0.1-0.3mm, it is convenient to use grinding of different precisions to produce molds with complex surfaces that meet the surface accuracy requirements.

[0044] Embodiment 2:

[0045] The difference between this embodiment and the first embodiment is that: according to the overall shape coordinate parameters of the complex curved surface mold, the mold is programmed to be polished after the tool is milled according to the machining tool path, and the speed of the free range is ground at a speed that is one-third of the speed of the removed part. In the process, the free range is ground using cutting fluid and micron-level corundum for auxiliary grinding. During the process, the fallen corundum and cutting fluid are continuously extracted, and the above-mentioned extraction process is removed using a vacuum device, which effectively prevents the fallen corundum and cutting fluid from interfering with the grinding process. In addition, the grinding chips can be quickly removed, and the cooling can be accelerated to a certain extent to avoid unnecessary errors in the complex curved surface of the mold caused by thermal deformation due to excessive grinding speed. In the above process, the grinding path can be readjusted according to the accuracy of the grinding tool.

[0046] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. An adaptive tool path planning method for complex surface mold processing, characterized in that: The following steps are involved: Step 1: Mold pre-modeling analysis According to the shape of the complex curved surface of the predetermined mold, the predetermined mold pre-cut features are constructed by splicing basic graphics, and the splicing and combination process of each basic graphic of the pre-cut features is recorded and reversely combined. During the process, the contour range of the pre-cut features and the spacing between the complex curved surface of the predetermined mold are controlled to be 0.1-0.3mm; Step 2: Pre-combination analysis of tool path shape According to the reverse combination of the basic graphics of the pre-cut features and the processing shapes of a single CNC milling tool, the features are compared, and the tool pre-cutting range is obtained by the method of minimum overlap area and the pre-cutting path with the fastest processing speed of each corresponding basic graphic is recorded; Step 3: Complex surface mold modeling On the basis of step 1, a model of a complex curved surface mold is constructed, and shape coordinate parameters of the curved surface are obtained. Then, the coincidence point of the pre-cut path and the shape coordinate parameters is obtained as the starting point of the next milling process and the machining tool path is regenerated. Step 4: Milling speed control According to the overlapping points obtained in step three, the gradient thickness range is obtained in combination with the position range distributed in the corresponding basic figure, and the milling speed is controlled in a manner that the distance gradient decreases and the speed increases according to the horizontal spacing of the gradient thickness range and the shape coordinate parameters, and the flow rate of the cutting fluid is controlled according to the milling speed.

2. The adaptive tool path planning method for complex curved surface mold processing according to claim 1, characterized in that: In the step 1, if the distance between the contour range of the basic figure of the pre-cut feature combination and the complex curved surface is greater than 0.1-0.3 mm, the corresponding local part is modeled in detail using parameterization.

3. The adaptive tool path planning method for complex curved surface mold processing according to claim 1, characterized in that: In the step 2, the reverse combination of the basic graphics and the area left in the middle of the pre-cut path are processed by first retaining and then sawing.

4. The adaptive tool path planning method for complex curved surface mold processing according to claim 1, characterized in that: In the step three, the pre-cut path restores the processing process of the complex curved surface mold according to the reverse combination of the basic graphics splicing, and adopts a layer-by-layer cutting method from top to bottom.

5. The adaptive tool path planning method for complex curved surface mold processing according to claim 1, characterized in that: The path generated in the process of regenerating the machining tool path by the pre-cut path is continuous. If the included overlapping point is within the range of the milling basic figure, it will continue to be completed. After the machining is completed, the tool will return to the corresponding overlapping point and move the tool again for machining. The above-mentioned tool moving path is the straight-line distance from the next basic figure to the overlapping point.

6. The adaptive tool path planning method for complex curved surface mold processing according to claim 5, characterized in that: The linear distance is adjusted to a local bending according to the moving angular range of the milling cutter to avoid tool collision.

7. The adaptive tool path planning method for complex curved surface mold processing according to claim 1, characterized in that: The free range from the cutting range corresponding to the machining tool path to the shape coordinate parameters is defined as the grinding range, and parametric grinding is performed.