CN107942928B - Tool path generation method for machining propeller blades - Google Patents
Tool path generation method for machining propeller blades Download PDFInfo
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- CN107942928B CN107942928B CN201711265213.7A CN201711265213A CN107942928B CN 107942928 B CN107942928 B CN 107942928B CN 201711265213 A CN201711265213 A CN 201711265213A CN 107942928 B CN107942928 B CN 107942928B
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- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
- G05B19/00—Programme-control systems
- G05B19/02—Programme-control systems electric
- G05B19/18—Numerical control [NC], i.e. automatically operating machines, in particular machine tools, e.g. in a manufacturing environment, so as to execute positioning, movement or co-ordinated operations by means of programme data in numerical form
- G05B19/19—Numerical control [NC], i.e. automatically operating machines, in particular machine tools, e.g. in a manufacturing environment, so as to execute positioning, movement or co-ordinated operations by means of programme data in numerical form characterised by positioning or contouring control systems, e.g. to control position from one programmed point to another or to control movement along a programmed continuous path
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- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
- G05B2219/00—Program-control systems
- G05B2219/30—Nc systems
- G05B2219/35—Nc in input of data, input till input file format
- G05B2219/35349—Display part, programmed locus and tool path, traject, dynamic locus
Abstract
The invention discloses a tool path generation method for processing propeller blades in the field of numerical control machine tool processing, which comprises the steps of firstly, segmenting a propeller blade surface curved surface to obtain a plurality of sub-curved surfaces, secondly, planning a tool path for each sub-curved surface, selecting proper feed direction, line spacing and step length precision in the process of planning the tool path for each sub-curved surface, generating a tool contact point track of each curved surface and calculating to generate a tool position point track, and finally, performing complementary processing on the boundary part of each sub-curved surface to intelligently realize the whole planning process.
Description
Technical Field
The invention relates to the technical field of numerical control machine tool machining, in particular to a method for generating a cutter path track of a propeller blade machined by a numerical control machine tool, which adopts the basic theoretical knowledge of curve modeling of a curved surface.
Background
The structure of the propeller blade is shown in fig. 1 and fig. 2, and comprises a propeller hub 1, a propeller blade surface 2 and a hub cap 6, when the propeller rotates, the track circle of the blade tip of the propeller is a tip circle 3, one side close to the turning direction of the propeller is a leading edge 4, and the other side is a trailing edge 5. The main processing content of the propeller blade is the propeller blade surface 2, so the tool path planning of the propeller blade is the tool path planning of the propeller blade surface 2.
In the existing processing method, the tool path track is generated by processing complex free-form surfaces such as the blade surface 2 of the propeller blade and the like in a planning mode of an isoparametric line method or a parallel section method, the isoparametric line method generates the tool path along the other parameter by keeping one of two parameters of a parameter curve unchanged, and curve data is directly used for generating the path. The parallel section method adopts a group of parallel sections to cut out a processing curved surface or an offset surface thereof, wherein the intersecting line of the processing curved surface is a cutter contact point track, and the offset surface is a cutter point track. In addition, the tool path planning process is more dependent on manual experience judgment, and the intellectualization degree of the whole planning process cannot be well and automatically realized through one planning process.
Disclosure of Invention
The invention aims to overcome the defects in the prior art and provides a blade path planning method for propeller blade machining, which can improve the quality of the machined surface of the propeller blade and reduce the formation of redundant blade paths.
The technical scheme adopted by the tool path generation method for processing the propeller blades is as follows: 1) dividing the blade surface of the propeller blade into each sub-curved surface, and determining the cutter shaft direction of the processing area of each sub-curved surface;
2) taking the tangent direction at the arc length midpoint of the longest boundary curve of the sub-curved surface as a feed direction, taking the normal direction as a line space direction, taking the arc length midpoint of the longest boundary curve of the sub-curved surface as a plane parallel to the feed direction and vertical to the line space direction, and taking the intersection line of the plane and the sub-curved surface as an initial trajectory line;
3) dispersing the initial trajectory line into a plurality of knife contacts according to step length precision, calculating a line space along the line space direction for each knife contact, and taking the minimum value of the line space as the line space between the current initial trajectory line and the next trajectory line;
4) the current initial trajectory line is biased in the line space direction by the line space to obtain the next trajectory line generated by the bias, and the iteration is carried out until the next trajectory line covers the whole processing area;
5) and (3) inwards offsetting the whole outer boundary line of the sub-curved surface by taking the actual cutting radius of the cutter as an offset distance to obtain a trimmed track line, and connecting the trimmed track lines end to obtain a cutter path track.
Further, after the tool path track is obtained, the boundary line of each sub-curved surface is subjected to complementary processing: firstly, determining the tool adding tool axis direction of the whole propeller blade surface, arbitrarily taking a boundary line on the propeller blade surface as a trajectory line to obtain a plurality of tool contacts on the trajectory line, then calculating tool positions according to the tool contacts, and generating a tool position point trajectory from the tool positions, namely the boundary line tool adding tool path; and finally, setting the advancing and retreating movement of each boundary line processing tool path, setting a public safety plane, lifting the tool to the public safety plane after the tool finishes processing one boundary line, and moving the tool to the vicinity of the next boundary line to process the next boundary line until the processing of each boundary line is finished.
The invention intelligently realizes the whole planning process by the cutter path planning of the fragmentation of the blade surface curved surface of the propeller, the cutter path planning of each fragmentation curved surface and the part of the boundary line of each fragmentation curved surface. The planned tool path track is suitable for a three-axis machine tool, and the processing cost is reduced.
Drawings
FIG. 1 is a front view of a propeller blade configuration;
FIG. 2 is a right side view of FIG. 1;
fig. 3 is an enlarged schematic view of the structure of the blade surface 2 of the propeller in fig. 1;
fig. 4 is a schematic sectional view of the blade surface 2 of the propeller in fig. 3;
fig. 5 is a schematic view of the cutter shaft of the sub-curved surface 9 in the blade surface 2 of the propeller in fig. 3;
FIG. 6 is an enlarged schematic view of the direction of the feeding and the line spacing of the sub-curved surface in FIG. 5;
FIG. 7 is a schematic diagram of initial trajectory formation for the subsurface of FIG. 6;
FIG. 8 is a schematic view of discrete blade contacts on the initial trace of FIG. 7;
FIG. 9 is a schematic diagram of an iterative process for generating the initial trajectory in FIG. 8;
FIG. 10 is a schematic view of a complete processing region trajectory comprised of the iteratively generated trajectory of FIG. 9;
FIG. 11 is a schematic diagram illustrating a track trimming process performed on the complete processing area track of FIG. 10;
FIG. 12 is a schematic diagram of the trace joining process of FIG. 10 after trimming;
FIG. 13 is a schematic view of non-cutting movement during machining of the sub-surface of FIG. 12;
fig. 14 is a schematic view of the direction of each sub-curved surface boundary line complement machining cutter shaft in the whole propeller blade surface 2;
fig. 15 is a schematic sectional boundary view of the propeller blade surface 2 shown in fig. 4;
FIG. 16 is a schematic diagram of exemplary boundary line discrete blade contacts;
fig. 17 is a schematic diagram of the compensation machining non-cutting movement of each sub-curved surface boundary line.
Detailed Description
The method comprises the steps of firstly, slicing the blade surface curved surface of the propeller to obtain a plurality of sub-curved surfaces. Secondly, planning a tool path for each sub-curved surface, selecting a proper feeding direction, a proper row spacing and a proper step length precision in the process of planning the tool path for each sub-curved surface, generating a tool contact point track of each curved surface and calculating to generate a tool location point track. And finally, performing complementary processing on the boundary part of each sub-curved surface. The specific implementation steps are as follows:
as shown in fig. 3 and 4, firstly, the blade surface 2 of the propeller blade in fig. 3 is sliced, and the blade surface 2 of the propeller blade is divided into different sub-curved surface areas which are processed in a numerical control manner, so that the concave-convex property of each point of each sub-curved surface area is the same and the curvature change is gentle during slicing, and therefore, when each sub-curved surface is processed, high surface quality can be obtained. As shown in fig. 4, the blade surface 2 of the propeller blade is divided into several concave curved surfaces 7, 8, 9, 10, and 17 and several convex curved surfaces 11, 12, 13, 14, 15, and 16.
And then planning the tool path of each sub-curved surface. The present invention is described by taking the sub-curved surface 9 in fig. 4 as an example, and the tool path planning method of the other sub-curved surfaces is the same as that of the sub-curved surface 9. The specific method comprises the following steps:
step 1: as shown in the enlarged view of the sub-curved surface 9 in fig. 5, the UV coordinate system is selected to determine the arbor direction of the processing area of the sub-curved surface 9. The normal vector direction of the sub-curved surface at the intersection point O where the U, V-direction parameters are all 0.5 is taken as the cutter shaft direction, the parameters of the U direction 18 and the V direction 19 in fig. 5 are all 0.5, and the normal vector direction at the intersection point O is taken as the cutter shaft direction 19.
Step 2: as shown in fig. 6, a tangential direction at the arc length midpoint a of the longest boundary curve of the sub-curved surface 9 is taken as a feeding direction 21, a normal direction is taken as a line space direction 22, and the feeding direction 21 and the line space direction 22 are perpendicular to each other. The line spacing is the distance between the corresponding tool contact or the corresponding tool location between two adjacent tracks, and is generally determined by the residual height, the tool geometry, and the curved geometry information.
And step 3: as shown in fig. 7, a plane 23 is drawn through the arc length midpoint a of the longest boundary curve of the sub-curved surface 9, parallel to the feeding direction 21 and perpendicular to the row pitch direction 22, and the intersection line of the plane 23 and the sub-curved surface 9 is taken as an initial trajectory line 24.
And 4, step 4: as shown in fig. 8, the initial trajectory line 24 is discretized to a number of blade contacts B with step accuracy. The tool contact point is a contact point between the tool and the surface of the part in the machining process, and a curve formed by all the tool contact points in the machining process of the tool is a tool contact point track.
And 5: for each tool contact point B on the initial trajectory line 24, the line space in the line space direction 22 is calculated by a conventional calculation method according to the characteristics of the sub-curved surface and the actual cutting condition of the tool, and the minimum value is taken as the line space between the current initial trajectory line 24 and the next trajectory line 25, so that the residual height is within the required range, as shown in fig. 9.
Step 6: as shown in fig. 9, the current initial trajectory line 24 is offset in the row space direction 22 by the row space, resulting in an offset-generated next trajectory line 25. This is iterated until the next trace 25 covers the entire machining area, as shown in fig. 10.
And 7: as shown in fig. 11, the entire outer boundary line of the sub-curved surface 9 is inwardly offset by an offset distance of the actual cutting radius of the tool, and the trajectory line is trimmed by the offset curve 26 generated by the offset, resulting in each trimmed trajectory line 27, so that the machining range of the tool is defined within the boundary of the offset curve 26.
And 8: as shown in fig. 12, the trimmed trajectory lines 27 are connected in a reciprocating (Zig Zag) manner, that is, the trimmed trajectory lines are connected end to end, so that the transfer path between the trajectory lines is short, and the cutting efficiency is improved. The continuous track line connected end to end, i.e. the tool path track of the sub-curved surface 9, generates a tool path.
And repeating the steps 1 to 8 to obtain the tool path tracks of the rest sub-curved surfaces 7, 8, 10, 17, 11, 12, 13, 14, 15 and 16. And then calculating a cutter point according to the cutter contact B of each sub-curved surface to generate a cutter point track, namely a processing cutter path of each sub-curved surface. The tool location point refers to a positioning reference point of the tool, each position of the tool in the machining process can be accurately determined, and the tool location point can be calculated through a tool contact point. In the machining process, the set of all tool positions is a tool position track, and the tool position track is a tool path track.
As shown in fig. 13, the feeding and retracting of the tool are provided for each sub-curved surface, and a common safety plane 30 is provided, the common safety plane 30 is provided on the requirement that the tool does not collide and interfere with the processing surface, and the tool is easy to reach, the tool approaches to the vicinity of the processing surface from the common safety plane 30 along the cutter shaft direction, then the feeding starts to process the processing surface, and the tool retracts and is lifted to the common safety plane after each tool path in one sub-curved surface is completed, so as to ensure that the tool does not interfere with the curved surface in the processing process. In fig. 13, the tool approaches the tool feeding path 28 from the common safety plane 30 along the non-cutting path 29 approaching the machining surface, starts machining the machining surface, moves the tool path in the sub-curved surface 9, retracts from the tool retracting path 32, and rises to the common safety plane 30 along the non-cutting path 31 of the tool raising to the safety plane.
In order to ensure the processing quality of the joint of each sub-curved surface, the boundary line of each sub-curved surface is taken as the path line of the contact point of the cutter, and the boundary of each sub-curved surface is subjected to complementary processing. The specific method comprises the following steps:
step 1: taking the normal vector direction of the curved surface of the blade surface at the point where the parameters from U, V to 34 and 33 on the blade surface 2 of the whole propeller are both 0.5 as the direction 35 of the cutter shaft for supplementing machining.
Step 2: as shown in fig. 15, any one of the boundary lines is taken as the knife contact trace line 36, and the knife contact C on the knife contact trace line is obtained according to the appropriate step length, as shown in fig. 16. This is repeated to obtain blade contacts for all boundary lines.
And step 3: and calculating a tool position point according to the tool contact, and generating a tool position point track from the tool position point, namely supplementing the tool path on the boundary line.
And 4, step 4: setting the feeding and retracting movement of each boundary line processing tool path, and setting a public safety plane, wherein the setting of the public safety plane takes the condition that a tool does not collide and interfere with a processing surface and the tool is easy to reach as a requirement, after one boundary line is processed, the tool is lifted to the public safety plane, moves to the vicinity of the next boundary line, and then approaches to the processing surface to feed for processing the next boundary line until the processing of each boundary line is finished. As shown in fig. 17, which is a partial view of the curved surfaces 11, 12, 13, 14, 15, 16 in fig. 4, taking the processing of two boundary lines 36, 37 in fig. 15 as an example, in fig. 17, a tool retracting path 38, a tool raising path 39, a tool approaching path 42 and a tool feeding path 43 for processing the boundary line 36, a tool approaching path 44, a tool feeding path 45, a tool raising path 46 and a tool retracting path 47 for processing the boundary line 37, and a common safety plane 40 are set, and after the processing of the boundary line 36 is completed, the tool is raised to the common safety plane 40, then moves to the vicinity of the boundary line 37 along a moving path 41, and is fed to the processing surface for processing the boundary line 37 until the processing of each boundary line is completed.
And finally, carrying out simulation verification on the planned tool path, and carrying out post-processing to output a numerical control program.
Claims (5)
1. A knife track generation method for machining propeller blades is characterized by comprising the following steps:
1) dividing the blade surface of the propeller blade into each sub-curved surface, and determining the cutter shaft direction of the processing area of each sub-curved surface;
2) taking the tangent direction at the arc length midpoint of the longest boundary curve of the sub-curved surface as a feed direction, taking the normal direction as a line space direction, taking the arc length midpoint of the longest boundary curve of the sub-curved surface as a plane parallel to the feed direction and vertical to the line space direction, and taking the intersection line of the plane and the sub-curved surface as an initial trajectory line;
3) dispersing the initial trajectory line into a plurality of knife contacts according to step length precision, calculating a line space along the line space direction for each knife contact, and taking the minimum value of the line space as the line space between the current initial trajectory line and the next trajectory line;
4) the current initial trajectory line is biased in the line space direction by the line space to obtain the next trajectory line generated by the bias, and the iteration is carried out until the next trajectory line covers the whole processing area;
5) and (3) inwards offsetting the whole outer boundary line of the sub-curved surface by taking the actual cutting radius of the cutter as an offset distance to obtain a trimmed track line, and connecting the trimmed track lines end to obtain a cutter path track.
2. The method for generating a blade path for processing a propeller blade as claimed in claim 1, wherein: after the tool path track is obtained, the boundary line of each sub-curved surface is subjected to complementary processing: firstly, determining the tool adding tool axis direction of the whole propeller blade surface, arbitrarily taking a boundary line on the propeller blade surface as a trajectory line to obtain a plurality of tool contacts on the trajectory line, then calculating tool positions according to the tool contacts, and generating a tool position point trajectory from the tool positions, namely the boundary line tool adding tool path; and finally, setting the advancing and retreating movement of each boundary line processing tool path, setting a public safety plane, lifting the tool to the public safety plane after the tool finishes processing one boundary line, and moving the tool to the vicinity of the next boundary line to process the next boundary line until the processing of each boundary line is finished.
3. The method for generating a blade path for processing a propeller blade as claimed in claim 2, wherein: and taking the normal vector direction of the blade surface curved surface at the point with 0.5 parameter in the direction of U, V direction of the UV coordinate system of the blade surface of the whole propeller as the direction of the cutter shaft for supplementing the machining.
4. The method for generating a blade path for processing a propeller blade as claimed in claim 1, wherein: in the step 1), the concave-convex property of each point in each divided sub-curved surface area is the same and the curvature change is smooth.
5. The method for generating a blade path for processing a propeller blade as claimed in claim 1, wherein: in the step 1), the normal vector direction of the sub-curved surface at the intersection point of which the U, V-direction parameters of the UV coordinate system are all 0.5 is taken as the cutter shaft direction.
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| CN111151795B (en) * | 2019-12-18 | 2021-06-11 | 沈阳透平机械股份有限公司 | Method and device for machining impeller blade of centrifugal compressor |
| CN112255966B (en) * | 2020-10-30 | 2021-11-23 | 西北工业大学 | Adaptive generation method for machining track of narrow and long free-form surface part |
| CN114211380A (en) * | 2022-02-21 | 2022-03-22 | 江苏天健智能装备制造有限公司 | End socket polishing path planning method based on equal step method |
| CN114888342B (en) * | 2022-04-26 | 2024-01-02 | 西安三航动力科技有限公司 | Method for machining blisk blade by adopting drum-shaped knife |
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| CN102436216A (en) * | 2011-11-24 | 2012-05-02 | 华中科技大学 | Method for generating spiral grinding tool locus for blade |
| CN103809510A (en) * | 2012-11-09 | 2014-05-21 | 沈阳高精数控技术有限公司 | Free curved surface reciprocating type cutter path planning method for high-precision processing |
| CN106054802A (en) * | 2016-07-28 | 2016-10-26 | 电子科技大学 | Free-form surface adaptive machining track planning method |
| CN106843140A (en) * | 2016-11-28 | 2017-06-13 | 北京动力机械研究所 | A kind of finishing tool method for planning track of double shrouded wheel |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| DE10322340B4 (en) * | 2003-05-17 | 2006-09-14 | Mtu Aero Engines Gmbh | Method and device for milling free-form surfaces |
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| CN102436216A (en) * | 2011-11-24 | 2012-05-02 | 华中科技大学 | Method for generating spiral grinding tool locus for blade |
| CN103809510A (en) * | 2012-11-09 | 2014-05-21 | 沈阳高精数控技术有限公司 | Free curved surface reciprocating type cutter path planning method for high-precision processing |
| CN106054802A (en) * | 2016-07-28 | 2016-10-26 | 电子科技大学 | Free-form surface adaptive machining track planning method |
| CN106843140A (en) * | 2016-11-28 | 2017-06-13 | 北京动力机械研究所 | A kind of finishing tool method for planning track of double shrouded wheel |
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