CN116430796A - Machining path local fairing method based on geometric clipping - Google Patents
Machining path local fairing method based on geometric clipping Download PDFInfo
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- 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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Abstract
The invention provides a geometric cutting-based local fairing method for a processing path, which comprises the steps of adopting a rounded corner strategy to bias an original processing path outwards and then bias inwards to obtain an arc-shaped closed curve formed by a turning line and an arc, respectively carrying out Boolean difference operation on the arc-shaped closed curve and the curves of the original processing path and the original processing path which are biased outwards by a tiny value to obtain a line segment set and an arc set, and splicing the line segments and the arc in the two sets according to the sequence to obtain the fairing curve of the original processing path. The local fairing method can generate a local fairing path with good continuity aiming at the processing paths of various complex contours including curves with curvature changes, has simple algorithm process and small operation amount, has good universality and robustness, generates a tool path which is smooth and suitable for high-speed processing, and finally achieves the aim of improving the processing efficiency.
Description
Technical Field
The invention belongs to the technical field of planar machining tool path fairing programming, and particularly relates to a machining path local fairing method based on geometric cutting.
Background
Along with automation, informatization and intellectualization of manufacturing industry, the requirements of high-speed high-precision multi-axis linkage numerical control systems in various industries are rapidly increased, such as industrial robot systems for welding, gluing, cutting and the like. Therefore, the high-speed high-precision five-axis linkage numerical control system has important strategic significance. In order to realize high-precision and high-efficiency machining, the primary task of the five-axis numerical control system is to generate smooth and high-efficiency cutter movement in real time. For this purpose, both path generation and feed rate planning are to be started.
In the actual machining process, the straight-line segment path is most widely used. However, when the machine tool is run to the corner of the small segment path, the change in direction of the tool produces a large centripetal acceleration. In particular, in the case of high-speed, high-precision and high-curvature machining, the higher acceleration can cause the vibration of the machine tool and the deterioration of the surface quality of the part. In addition, since interpolation computation is complex and time-consuming, it is generally performed off-line, and the processing efficiency is reduced. Currently numerical control programs are typically expressed in code form conforming to the ISO 6983 standard, wherein the tool path is typically a discrete linear path, the G01 code. The linear tool path is tangentially discontinuous at the corners and, to reduce speed fluctuations, commercial numerical control systems typically use feed speeds well below the commanded value through the corners. In order to make the machine tool run smoothly during machining and to improve the machining efficiency, it is necessary to smooth the straight path.
Aiming at the strategy of acquiring the path of the fairing tool in numerical control machining, the existing track fairing method is mainly divided into two types, namely global track fairing and local track fairing, namely corner fairing. Global fairing is the approximate replacement of a straight line segment path with a spline curve, while local fairing refers to the replacement of the corners of each straight line segment trajectory with a spline curve. The existing path global fairing method has the advantages that the continuity of the whole path can be ensured, but the deviation between a new spline path after global fairing and an original small line segment path is difficult to be restrained. Therefore, the calculation method is simple, and the local fairing method with small calculation amount has more practical significance.
Disclosure of Invention
In order to realize a cutter path local fairing method with smaller calculated amount and faster speed, the invention provides a local processing path fairing method based on geometric cutting, which solves the problem of path deviation of the existing global fairing method and the performance deficiency of most local fairing methods. Compared with a global fairing method, the method has high reduction degree on the original path on the basis of realizing the global continuity of the path as much as possible; on the basis of keeping universality and robustness, aiming at the contour boundary of a curve with different curvatures, acquiring a 'round angle' at a boundary turning position through basic geometric cutting and Boolean operation, and outputting a final fairing path through line segment splicing so as to realize high-speed and high-efficiency processing.
A processing path local fairing method based on geometric clipping comprises the following steps:
(1) The input processing path b with turning angle 0 The outward offset distance R, the turning angle adopts an offset strategy of arc connection, the radius of the arc is R, and a closed curve b is obtained m ；
(2) Will b m Bias into its enclosed region to obtain curve b n ，b n Two end points of each arc are positioned at b 0 And b n Each arc of (b) 0 The turning lines between the two ends of the arc form an arc closed curve together, and all the arc closed curves form a set { p } i -a }; wherein i is E [1, M]M represents the number of arcuate closed curves;
(3) Will { p } i Each arcuate closed curve in } is offset outwardly by a distance d 1 Obtain the set { q } i }；
(4) Will b 0 Biasing delta outward to obtain closed curve b s In the two-dimensional plane, will { q i And b 0 And b s Respectively performing Boolean difference operation to obtain segment set { L ] j Sum of arcs { S } and i -a }; wherein j is E [1, M+1 ]]；
(5) Sequentially { L } j Sum { S } i Splicing to obtain curve b p The method comprises the steps of carrying out a first treatment on the surface of the Pair b p The multi-segment line simplification is carried out on all the top points to obtain a rounded fairing curve b f 。
In the above step, b is input 0 Is a non-closed curve, is a multi-section line comprising a plurality of points; b 0 Is a processing path with turning angle generated by the prior processing path generation technology and comprises the condition of curve-straight line mixingThe condition is as follows. The offset distance and the arc radius R are taken as the whole original path b 0 The fillet radius in local smoothing is a set value, and the value depends on the original processing path b 0 Is a specific structure of (a).
Pair b in step (1) and step (4) 0 Biasing outwardly means that b 0 Respectively biasing the inner side and the outer side of the two bias lines, and respectively connecting the corresponding two ends of the two bias lines obtained by the biasing to form a surrounding b 0 Is a closed curve of (a). Strategy pair b using circular arc connection in step (1) 0 Biasing can be at b 0 The arc with the specified radius R is obtained at the position corresponding to the turning angle, so that the later extraction and splicing are facilitated.
Preferably, in step (2), the closed curve b m The distance biased into the enclosed region is- (R + delta), where the symbol "-" indicates direction. Original path b 0 The purpose of biasing outwards and inwards is to obtain a circular arc and an arc-shaped closed curve, and the closed curve b m Is formed by b 0 The outward offset distance R is obtained, in practice, by taking the straight portion and b 0 Curve b with partially coincident straight lines n Will close curve b m The inward bias-R distance is not practical and requires a small increase in the bias distance to achieve.
Preferably, the offset distance d in step (3) 1 And (3) not more than the offset distance delta in the step (4), wherein delta is a tiny value.
Step (3) outwardly biasing each arcuate closed curve a distance d 1 Is to take d for the convenience of subsequent cutting operation 1 ＝5。
Preferably, in the step (3), the arcuate closed curve is biased outwards (bias amplification), that is, the turning line and the circular arc forming the arcuate closed curve are respectively biased away from the arcuate region defined by the two, and the turning line and the circular arc scribing after the biasing are connected by the circular arc.
Preferably, in steps (1) and (4), two-dimensional graphic computing library pairs b are used, respectively 0 An outward bias is performed.
Preferably, in the step (5), the method comprises{L j Sum { S } i And comparing the end point coordinates of the line segment and the circular arc in the middle, and splicing the line segment and the circular arc according to the comparison sequence.
Specifically, in step (5), the line segments { L } are collected in order j Sum of arcs { S } and i the specific operation of the splicing is as follows:
taking b 0 Either of the terminal sites serves as a head site (x 0 ,y 0 ) Pair of line segment sets { L ] j Traversing the inner line segment, taking one end point as (x) 0 ,y 0 ) As line segment L 0 Let L 0 The other end point is (x) 1 ,y 1 ) And is defined as L 0 Tail end of (2); then for the circular arc set { S } i Traversing, taking one end point as (x) 1 ,y 1 ) Arc S of (2) 0 Let S 0 The other end point is (x) 2 ,y 2 ) And is defined as S 0 Tail end of (2); then take { L } j One end point in the } is (x) 2 ,y 2 ) As line segment L 1 Thus circulate in turn from { L j Sum { S } i Taking out the corresponding line segment and the circular arc from the first and the last splice to obtain a curve b p 。
Compared with the prior art, the invention has the beneficial effects that:
according to the processing path local fairing method based on geometric clipping, an original processing path is outwards biased by adopting a rounded corner strategy and then inwards biased to obtain an arc-shaped closed curve formed by a turning line and an arc, the arc-shaped closed curve, the original processing path and the curve of which the original processing path are outwards biased by a tiny value are respectively subjected to Boolean difference operation to obtain a line segment set and an arc set, and the line segments and the arcs in the two sets are spliced in sequence to obtain the fairing curve of the original processing path. The local fairing method can generate a local fairing path with good continuity aiming at the processing paths of various complex contours including curves with curvature changes, has simple algorithm process and small operation amount, has good universality and robustness, generates a tool path which is smooth and suitable for high-speed processing, and finally achieves the aim of improving the processing efficiency.
Drawings
FIG. 1 is a flow chart of a method for local fairing of a processing path based on geometric clipping according to an embodiment of the invention;
FIG. 2 shows the original processing path b 0 Performing bias treatment and obtaining a schematic diagram of an arcuate closed curve set;
FIG. 3 is a set { q } i And original processing path b 0 Acquiring a non-corner line segment (linear line segment) set schematic diagram through Boolean difference operation;
FIG. 4 is a set { q } i And closed curve b s Obtaining a circular arc set schematic diagram at a corner through Boolean difference operation;
fig. 5 is a graph comparing a partial fairing back path (a) and an original tooling path (b) generated using the method of an embodiment of the present invention.
Detailed Description
The technical solution of the present invention will be further described in detail with reference to the drawings and the specific embodiments of the present invention, it should be understood that the specific embodiments described herein are only for explaining the present invention and are not limiting the present invention.
As shown in fig. 1, a method for local fairing of a processing path based on geometric clipping includes the following steps:
step 101: inputting an original processing path b with turning angles 0 Offset radius R.
Input raw machining path b 0 Is a non-closed multi-segment line comprising a plurality of points. The offset radius R determines the corner radius of the final output fairing curve at the turn.
Step 102: curve b is calculated by using two-dimensional graph 0 Biased outwardly by a distance d 0 R, obtaining a closed curve b comprising an arc m . Strategy pair b adopting circular arc connection 0 Is biased outwards and can be carried out in the original processing path b 0 And a fillet with a specified radius (R) is obtained at the position corresponding to the turning angle and is used for later extraction and splicing.
This step ultimately outputs a closed fairing curve b m 。
Step 103:
step 103-1: will b m Bias into the closed region- (R+delta) gives curve b n ，b n Two end points of each arc are positioned at b 0 And b 0 The turning line between two end points of the previous arc and the arc form an arc-shaped closed curve together, and all the arc-shaped closed curves form a set { p } i (as shown in FIG. 2, set { p } in FIG. 2 i Shown as a set of arcuate curves); wherein i is E [1, M]M represents the number of arcuate closed curves;
step 103-2: for subsequent clipping operations, for the set { p } i Bias amplification, i.e. given a short distance d 1 (usually take d 1 =5), to obtain a biased arcuate closed curve set { q } i }。
Step 104: curve b is calculated by using two-dimensional graph 0 Performing outward bias by a small value delta to obtain a curve b s 。
Step 105: as shown in FIGS. 3 and 4, in a two-dimensional plane { q } i And b 0 And b s Respectively performing Boolean difference operation and respectively processing the original processing path b 0 Sum { q i Cutting each arcuate closed curve in the sequence to obtain a segment set { L } j Sum of arcs { S } and i -a }; wherein j is [1, M+1 ]]。
Step 106:
step 106-1: for the segment set { L } obtained in step 105 j Sum of rounded curves { S } i Comparing the end point coordinates of the line segment and the circular arc in the process of the comparison, and splicing the line segment and the circular arc according to the comparison sequence to obtain a complete rounded curve b p ；
Specifically:
taking b 0 Either of the terminal sites serves as a head site (x 0 ,y 0 ) Pair of line segment sets { L ] j Traversing the inner line segment, taking one end point as (x) 0 ,y 0 ) As line segment L 0 Let L 0 The other end point is (x) 1 ,y 1 ) And is defined as L 0 Tail end of (2); then for the circular arc set { S } i Traversing and takingOne of the end points is (x) 1 ,y 1 ) Arc S of (2) 0 Let S 0 The other end point is (x) 2 ,y 2 ) And is defined as S 0 Tail end of (2); then take { L } j One end point in the } is (x) 2 ,y 2 ) As line segment L 1 Thus circulate in turn from { L j Sum { S } i Taking out the corresponding line segment and the circular arc from the first and the last splice to obtain a curve b p 。
Step 106-2: to reduce too dense point-to-curve b in the path p The multi-segment line simplification is carried out on all the peaks on the upper surface to obtain a final rounded curve b f 。
The generating method of the embodiment is implemented by a c++ programming language, and typical application examples are as follows:
an example selects a processing path having a curved shape, as shown in fig. 5 (b), the maximum width of which is 1280mm and the maximum height of which is 426mm. The figure is characterized in that a plurality of turning angles exist and the whole path is formed by mixing straight line segments and curved line segments, and the areas have a plurality of sharp corners (turning angles) in the processing process, so that high-speed processing cannot be realized.
In the test procedure, a bias radius r=15 mm is set; the offset amplification distance of the arcuate closed curve is set to d i ＝5；b 0 The outward bias is performed to obtain a curve b s Is offset by delta=5. Fig. 5 (a) shows a partial fairing path diagram generated by the generating method of the embodiment, and the diagram shows that all turning corners of the original processing path are replaced by the smooth fillets, the connection transition between the straight line segment and the curve segment is smooth, and the path after partial fairing is suitable for high-speed processing and has high processing efficiency. Therefore, the processing path obtained by the generating method of the present embodiment has higher processing efficiency than that obtained by the ordinary method.
The foregoing is merely a preferred embodiment of the present invention, and it should be noted that various modifications and changes of the present invention will occur to those skilled in the art. Any modification, equivalent replacement, improvement, etc. made without departing from the principle of the present invention should be included in the protection scope of the present invention.
Claims (4)
1. The local fairing method of the processing path based on geometric clipping is characterized by comprising the following steps:
(1) The input processing path b with turning angle 0 The outward offset distance R, the turning angle adopts an offset strategy of arc connection, the radius of the arc is R, and a closed curve b is obtained m ；
(2) Will b m Bias into its enclosed region to obtain curve b n ，b n Two end points of each arc are positioned at b 0 And b n Each arc of (b) 0 The turning lines between the two ends of the arc form an arc closed curve together, and all the arc closed curves form a set { p } i -a }; wherein i is E [1, M]M represents the number of arcuate closed curves;
(3) Will { p } i Each arcuate closed curve in } is offset outwardly by a distance d 1 Obtain the set { q } i }；
(4) Will b 0 Biasing delta outward to obtain closed curve b s In the two-dimensional plane, will { q i And b 0 And b s Respectively performing Boolean difference operation to obtain segment set { L ] j Sum of arcs { S } and i -a }; wherein j is E [1, M+1 ]]；
(5) Sequentially { L } j Sum { S } i Splicing to obtain curve b p The method comprises the steps of carrying out a first treatment on the surface of the Pair b p The multi-segment line simplification is carried out on all the top points to obtain a rounded fairing curve b f 。
2. The geometric clipping-based processing path local fairing method according to claim 1, wherein the offset distance d in step (3) 1 And (3) not more than the offset distance delta in the step (4), wherein delta is a tiny value.
3. The geometric clipping-based processing path local fairing method according to claim 1, wherein the two-dimensional graphic calculation library pairs b are used in the steps (1) and (4), respectively 0 An outward bias is performed.
4. The geometric-clipping-based processing path local fairing method according to claim 1, wherein in step (5), for { L j Sum { S } i And comparing the end point coordinates of the line segment and the circular arc in the middle, and splicing the line segment and the circular arc according to the comparison sequence.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116738621A (en) * | 2023-08-09 | 2023-09-12 | 武汉华锋惠众科技有限公司 | Method, system, electronic equipment and storage medium for constructing derivative curved surface |
| CN116861570A (en) * | 2023-09-04 | 2023-10-10 | 武汉华锋惠众科技有限公司 | Boundary fairing method for automobile panel |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116738621A (en) * | 2023-08-09 | 2023-09-12 | 武汉华锋惠众科技有限公司 | Method, system, electronic equipment and storage medium for constructing derivative curved surface |
| CN116738621B (en) * | 2023-08-09 | 2023-11-17 | 武汉华锋惠众科技有限公司 | Method, system, electronic equipment and storage medium for constructing derivative curved surface |
| CN116861570A (en) * | 2023-09-04 | 2023-10-10 | 武汉华锋惠众科技有限公司 | Boundary fairing method for automobile panel |
| CN116861570B (en) * | 2023-09-04 | 2023-11-24 | 武汉华锋惠众科技有限公司 | Boundary fairing method for automobile panel |
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