DE102022101000B4 - Method and apparatus for generating a CAM-oriented time spline curve and surface - Google Patents

Abstract

Method for generating a CAM-oriented time spline curve and surface, characterized in that it comprises the following steps: Step S1: Presetting a residual height error E, determining a first number of toolpaths on the initial surface S (u, v) based on the constraint Emde residual height error E and converting each of the first number of toolpaths into a time spline curve to obtain the first number of time spline curves, the step S1 specifically comprisingStep S11: converting an initial parameter curve S( u,v) according to the dynamic performance of the machine tool and the machining error limitation into a time-based curve r0(t) based on the initial surface r0(u)|v=0; Step S12: Calculate a bandwidth dt,j(t,E) ( where j = 1,2,...,n), which satisfies the residual height error constraint Em, in the parameter direction v using the curve r0(u) |v=0 as an initial curve; Step S13: Calculate a tool path rj satisfying the curve r0( u) |v=0 is used as the initial tool trajectory and the residual height error constraint Em is satisfied, according to the bandwidth dt,j(t,E); converting the tool path rj into a time-based curve r(t)j according to the dynamic performance of the machine tool and the machining error constraint; step S14 : repeating step S13 until the entire surface of the initial surface S(u,v) is covered; step S2: discretizing the first number of time spline curves into a point column according to a preset time step and performing surface reconstruction for the point column, to obtain a surface with time and residual height error E as parameters, wherein step S2 specifically comprisesStep S21: Obtaining a discrete point column P{pi,j, i = 1,...,m; j = 1,...,n} on the entire discrete surface according to a preset time step δt; Step S22: Perform a surface reconstruction according to the discrete point column P{pi,j, i = 1,...,m;j = 1 ,...,n} to obtain a reconstructed surface S(t,dt,j(t,E)) such that all discrete point columns P{pi,j, i =1,...,m; j =1,...,n} are located on the reconstructed surface S(t,dt,j(t,E)) and the error bound of the Hausdorff distance is satisfied in the discrete sense with the initial surface S(u,v); Step S3: Generate a tool path for the surface with time and residual height error E as parameters according to the residual height error constraint Emder machining requirements and use a time spline curve that satisfies the residual height error constraint E and the dynamic power constraint of the machine tool as a tool path, the step S3 specifically comprising step S31: Record the individual time-spline curves r(t)j corresponding to the discrete point columns in step S2; Step S32: Assign the parameters of the time-based spline curve r(t)j to those of the reconstructed surface S(t ,dt,j(t,E));Step S33: Determine the interval of the new time spline curve based on the magnitude relationship between the residual height error restriction Em required for actual processing and the preset residual height error E;Step S34: determining the time spline curve obtained in step S1 adjacent to the new time spline curve based on the interval size of the new time spline curve and performing linear interpolation according to the adjacent time spline curve in step S1 to determine a new time spline curve; step S35: optimize the new time spline curve obtained by step S34 so that the optimized tool path achieves the dynamic performance and error limitation of the machine tool Fulfills.

Description

FIELD OF THE INVENTION

The present application relates to the technical field of CNC machine tools, in particular a method for generating a CAM-oriented time spline curve and surface.

STATE OF THE ART

When CNC machine tools machine complex curved surfaces, they generally discretize complex curved surfaces into a large number of continuous polyline segments or smooth curves, and input polyline segments or curves into a CNC system as a tool machining path for machining. Although such a continuous polyline segment processing method is easy to calculate and can realize real-time processing, the amount of input data is large, frequent starting and stopping is expected when processing at a corner, and the processing efficiency is relatively low. Another method is high-speed and high-precision machining, which generally uses a spline curve toolpath for machining. Although spline curve has the advantages of small data amount and smooth machining trajectory compared to discrete polyline segments, and at the same time higher editing efficiency because it does not require frequent starting and stopping, but both polyline segment editing and spline curve editing require speed planning required during CNC machining, so that the machining trajectory not only meets the machining error requirements but also the dynamic performance limitations of the machine tool. The existing spline interpolation algorithms require two processes, namely speed planning and interpolation calculation, in the numerical control system, and it is difficult to meet the real-time requirements.

Therefore, it is necessary to provide a method for generating a time spline surface that can not only meet the machining efficiency and machining accuracy but also meet the real-time machining requirements.

DE 10 2011 082 800 A1 relates to a system and a method for the automated creation of robot programs.

CN 1 12 255 966 A disclosed a self-adaptive method for generating machining traces for curved parts of short length.

CN 1 06 547 251 describes a method for generating a five-axis milling path based on information feedback through interpolation in a sensitive area at low speed.

Zhong et al. International Journal of Automation and Computing, Vol. 17, 2020, pp. 1-16 is a review article concerning the interpolation and smoothing of toolpaths for the computer numerically controlled machining of freeform surfaces.

Disclosure of the invention

The exemplary embodiment of the present description is based on the object of providing a method for generating a CAM-oriented time spline curve and surface and an associated device in order to provide a method for generating a time spline surface that not only improves processing efficiency and Not only can meet machining accuracy, but also meet real-time machining requirements.

• Die vorliegende Erfindung stellt ein Verfahren zum Erzeugen einer CAM-orientierten Zeit-Spline-Kurve und -Oberfläche gemäß Anspruch 1 sowie eine Vorrichtung gemäß Anspruch 3 bereit.

According to the exemplary embodiment of the present description, the task is solved by the following:

• The present invention provides a method for generating a CAM-oriented time spline curve and surface according to claim 1 and an apparatus according to claim 3.

• Wenn mit der technischen Lösung der Erfindung komplexe gekrümmte Oberflächen bearbeitet werden, kann eine Zeit-Spline-Kurve automatisch als Werkzeugweg auf der zu bearbeitenden komplexen gekrümmten Oberfläche gemäß dem Resthöhenfehler erzeugt werden. Daher kann die gekrümmte Oberfläche, die nach der Rekonstruktion der erzeugten Zeit-Spline-Oberfläche erhalten wird, als eine Zeit-Spline-Oberfläche betrachtet werden. Die Zeit-Spline-Oberfläche kann automatisch einen Werkzeugweg gemäß dem Resthöhenfehler erzeugen und kann beim Erzeugen des Werkzeugweges nicht nur die Anforderungen des Resthöhenfehlers erfüllen, sondern auch eine einfache und schnelle Berechnung durchführen. Zusätzlich hat der erzeugte Werkzeugweg die Vorteile der Spline-Kurvenbearbeitung, nämlich hinsichtlich der Datenmenge, des glatten Weges und der hohen Verarbeitungseffizienz. Gleichzeitig erfüllt die Zeit-Spline-Kurve die Anforderungen der dynamischen Leistung und des Bearbeitungsfehlers der Werkzeugmaschine. Die Zeit wird als Parameter herangezogen und es nicht notwendig, eine Geschwindigkeitsplanung der Spline-Kurve durchzuführen. Vielmehr wird direkt eine Interpolationsberechnung gemäß den Zeitparametern durchgeführt. Somit werden die Vorteile einer einfachen und bequemen Berechnung erreicht. Die Echtzeit-Bearbeitungsanforderungen der Werkzeugmaschine können erfüllt werden und die Eigenschaften von hoher Geschwindigkeit und hoher Präzision werden erreicht. Die Zeit-Spline-Oberfläche, die durch die vorliegende Erfindung erzeugt wird, integriert die Arbeit der Geschwindigkeitsplanung im CNC-System. Basierend auf der Oberfläche können die Werkzeugwegerzeugung und die Geschwindigkeitsplanung miteinander kombiniert werden, was nicht nur die Rechenkomplexität der Werkzeugwegerzeugung reduziert, sondern auch die Berechnungseffizienz des Geschwindigkeitsplanungsalgorithmus effektiv verbessert, womit die endgültige Hochgeschwindigkeits- und Hochbearbeitungsanforderung erfüllt und schließlich die Bearbeitung komplexer gekrümmter Oberflächen erreicht wird.

With at least one of the exemplary embodiments of the present description, the following advantageous effects can be achieved:

• When complex curved surfaces are machined with the technical solution of the invention, a time spline curve can be automatically generated as a tool path on the complex curved surface to be machined according to the residual height error. Therefore, the curved surface obtained after reconstructing the generated time spline surface can be considered as a time spline surface. The time spline surface can automatically generate a tool path according to the residual height error, and when generating the tool path, it can not only meet the requirements of the residual height error, but also perform simple and quick calculation. In addition, the generated tool path has the advantages of spline curve processing, namely in terms of data quantity, smooth path and high processing efficiency. At the same time, the time spline curve meets the requirements of machine tool dynamic performance and machining error. Time is used as a parameter and it is not necessary to perform speed planning of the spline curve. Rather, an interpolation calculation is carried out directly according to the time parameters. Thus, the advantages of a simple and convenient calculation are achieved. The real-time machining requirements of the machine tool can be met, and the characteristics of high speed and high precision are achieved. The time spline surface created by the present invention integrates the work of speed planning in the CNC system. Based on the surface, tool path generation and speed planning can be combined together, which not only reduces the computational complexity of tool path generation, but also effectively improves the calculation efficiency of the speed planning algorithm, thereby meeting the final high-speed and high-speed machining requirement, and finally achieving the machining of complex curved surfaces.

Presentation of the invention

• 1 ein schematisches Ablaufdiagramm eines Verfahrens zum Erzeugen einer CAM-orientierten Zeit-Spline-Kurve und -Oberfläche gemäß der technischen Lösung des Ausführungsbeispiels der vorliegenden Beschreibung,
• 2 eine schematische Darstellung der mehreren Werkzeugwege, die keine Zeitparameter enthalten und gemäß einem voreingestellten Resthöhenfehler E auf der anfänglichen Oberfläche bestimmt werden, in der technischen Lösung des Ausführungsbeispiels der vorliegenden Beschreibung
• 3 eine schematische Darstellung des Umwandlungseffekts des Umwandelns eines Werkzeugweges, der keinen Zeitparameter enthält, in eine Zeit-Spline-Kurve, die eine Restfehlerbeschränkung und einen Zeitparameter enthält, in der technischen Lösung des Ausführungsbeispiels der vorliegenden Beschreibung,
• 4 eine schematische Darstellung des Rekonstruktionseffekts der Rekonstruktion mehrerer Zeit-Spline-Kurven in eine Oberfläche in der technischen Lösung des Ausführungsbeispiels der vorliegenden Beschreibung,
• 5 eine schematische Darstellung des Vergleichs der anfänglichen Oberfläche mit der rekonstruierten Oberfläche in der technischen Lösung des Ausführungsbeispiels der vorliegenden Beschreibung,
• 6 eine schematische strukturelle Darstellung einer Vorrichtung zum Erzeugen einer CAM-orientierten Zeit-Spline-Kurve und -Oberfläche gemäß der technischen Lösung des Ausführungsbeispiels der vorliegenden Beschreibung.

In order to better explain the technical solution in the exemplary embodiments according to the present description or in the prior art, the accompanying drawings used in the explanation of the exemplary embodiments or the prior art are briefly described below, it being understood that the following drawings only represent some exemplary embodiments of the application and it is possible for those of ordinary skill in the art to obtain further drawings from such drawings without any inventive steps. Show in it

• 1 a schematic flowchart of a method for generating a CAM-oriented time spline curve and surface according to the technical solution of the exemplary embodiment of the present description,
• 2 a schematic representation of the multiple tool paths, which do not contain time parameters and are determined according to a preset residual height error E on the initial surface, in the technical solution of the embodiment of the present description
• 3 a schematic representation of the conversion effect of converting a tool path containing no time parameter into a time spline curve containing a residual error constraint and a time parameter in the technical solution of the embodiment of the present description,
• 4 a schematic representation of the reconstruction effect of reconstructing several time spline curves into a surface in the technical solution of the exemplary embodiment of the present description,
• 5 a schematic representation of the comparison of the initial surface with the reconstructed surface in the technical solution of the exemplary embodiment of the present description,
• 6 a schematic structural representation of a device for generating a CAM-oriented time spline curve and surface according to the technical solution of the exemplary embodiment of the present description.

CONCRETE EMBODIMENTS

For a better understanding of the task, the design and the advantages of one or more exemplary embodiments of the present invention, the configurations of one or more exemplary embodiments according to the present description will be fully and clearly explained below using the accompanying drawings and specific exemplary embodiments of the description. It is understood that the exemplary embodiments described represent only a part of the exemplary embodiments of the present description rather than all of the exemplary embodiments.

As listed above, when machining complex curved surfaces with CNC machine tools, generally complex curved surfaces are discretized into a large number of continuous polyline segments or smooth curves, which are input into a CNC system as a tool machining path for machining. The amount of machining data of continuous polyline segments is large and frequent starting and stopping is expected at corners, resulting in low machining efficiency. Therefore, it is necessary to provide a method for producing a spline surface that can not only meet machining efficiency but also meet machining accuracy requirements.

The configurations of the individual exemplary embodiments of the present description which is described in detail below using the drawings.

1 shows a schematic flowchart of a method for generating a CAM-oriented time spline curve and surface according to an exemplary embodiment of the present description. From a program perspective, the process can be carried out by a program that is installed on an application server or an application terminal.

• Schritt S1: Voreinstellen eines Resthöhenfehlers E, Bestimmen einer ersten Anzahl von Werkzeugwegen auf der anfänglichen Oberfläche S(u,v) basierend auf der Beschränkung E_m des Resthöhenfehlers E und Umwandeln jedes der ersten Anzahl von Werkzeugwegen in eine Zeit-Spline-Kurve, um die erste Anzahl von Zeit-Spline-Kurven zu erhalten.

As in 1 shown, the process may include the following steps:

• Step S1: Preset a residual height error E, determine a first number of toolpaths on the initial surface S(u,v) based on the constraint E _m of the residual height error E, and convert each of the first number of toolpaths into a time spline curve to get the first number of time spline curves.

As in 2 shown, S(u,v) represents the initial surface on which multiple toolpaths are determined. The toolpath is marked S _i . As in 3 shown, taking one of the tool paths as an example, the tool path S _i , which does not contain any time parameters, is converted into a time spline curve D(t, E _i ), which contains a constraint E _m of the residual height error E and a time parameter, and finally become, as in the left half of 4 shown, time spline curves are obtained containing constraints E _m of the residual height error E and time parameters and their number of the number of tool paths in 2 corresponds.

Step S2: Discretize the first number of time spline curves into a point column according to a preset time step and perform surface reconstruction on the point column to obtain a surface with time and residual height error E as parameters.

As in 4 shown, an interpolation time is set in this step and all time spline curves obtained in step S1 are discretized into point columns based on which a surface reconstruction is performed, thus the one in the right half of 4 surface shown is obtained, which uses the time and the residual height error E as parameters.

Step S3: Generate a tool path for the surface with time and residual height error E as parameters according to the residual height constraint E _m of the machining requirements, and use a time spline curve that satisfies the residual height error constraint E _m and the dynamic power constraint of the machine tool as a tool path.

The surface reconstruction was performed in step S2. A surface is thus obtained with time and residual height error E as parameters.

After a tool path is generated for the reconstructed surface according to the residual height error constraint E _m of the machining requirements, the obtained time spline curve, which can satisfy the residual height error constraint E _m and the dynamic power constraint of the machine tool, is used as the tool path, thereby meeting the machining requirements of the CNC -Machine tool for the complex surface can be met. As in 5 shown, shows the left half of 5 schematically the initial surface in 2 (to clearly compare this initial surface with the reconstructed surface is in 5 no reference symbol shown), and the right half schematically shows the reconstructed surface. It can be seen that there is only a small difference in the shape of the two surfaces, which is within the error range of complex surface machining.

When complex curved surfaces are machined with the technical solution of the invention, a time spline curve can be automatically generated as a tool path on the complex curved surface to be machined according to the residual height error E. Therefore, the curved surface obtained after reconstructing the generated time spline surface can be considered as a time spline surface. The time spline surface can automatically generate a tool path according to the residual height error E, and when generating the tool path, it can not only meet the requirements of the residual height error E, but also perform simple and quick calculation. In addition, the generated tool path has the advantages of spline curve processing, namely in terms of data quantity, smooth path and high processing efficiency. At the same time, the time spline curve meets the requirements of machine tool dynamic performance and machining error. Time is used as a parameter and it is not necessary to perform speed planning of the spline curve. Rather, an interpolation calculation is carried out directly according to the time parameters. Thus, the advantages of a simple and convenient calculation are achieved. The real-time machining requirements of the machine tool can be met, and the characteristics of high speed and high precision are achieved. The time spline surface created by the present invention is generated, integrates the work of speed planning in the CNC system. Based on the surface, tool path generation and speed planning can be combined together, which not only reduces the computational complexity of tool path generation, but also effectively improves the calculation efficiency of the speed planning algorithm, thereby meeting the final high-speed and high-speed machining requirement, and finally achieving the machining of complex curved surfaces.

• Schritt S11: Umwandeln einer anfänglichen Parameterkurve S(u,v) gemäß der dynamischen Leistung der Werkzeugmaschine und der Bearbeitungsfehlerbeschränkung in eine zeitbasierte Kurve r₀ (t) basierend auf der anfänglichen Oberfläche r₀ (u) |_v=0;
• Schritt S12: Berechnen einer Bandbreite d_t,j (t,E) (wobei j =1,2,...,n), die die Resthöhenfehlerbeschränkung E_m erfüllt, in der Parameterrichtung v unter Verwendung der Kurve r₀ (u) |_v=0 als Anfangskurve;
• Schritt S13: Berechnen eines Werkzeugweges r_j, der die Kurve r₀ (u) |_v=0 als anfängliche Werkzeugtrajektorie verwendet und die Resthöhenfehlerbeschränkung E_m erfüllt, gemäß der Bandbreite d_t,j (t,E);

More specifically, step S1 specifically includes the following:

• Step S11: Converting an initial parameter curve S(u,v) according to the dynamic performance of the machine tool and the machining error limitation into a time-based curve r ₀ (t) based on the initial surface r ₀ (u) | _v=0 ;
• Step S12: Calculate a bandwidth d _t,j (t,E) (where j =1,2,...,n) that satisfies the residual height error constraint E _m in the parameter direction v using the curve r ₀ (u) | _v=0 as initial curve;
• Step S13: Calculate a tool path r _j that has the curve r ₀ (u) | _v=0 is used as the initial tool trajectory and the residual height error constraint E _m is satisfied, according to the bandwidth d _t,j (t,E);

• Schritt S14: Wiederholen des Schritts S13, bis die gesamte Oberfläche der anfänglichen Oberfläche S(u,v) abgedeckt ist.

Converting the tool path r _j into a time-based curve r(t) _j according to the dynamic performance of the machine tool and the machining error limitation;

• Step S14: Repeat step S13 until the entire surface of the initial surface S(u,v) is covered.

• S111: Umwandeln der Datenpunkte in einem Werkstückkoordinatensystem gemäß den Strukturparametern der Werkzeugmaschine in ein Werkzeugmaschinenkoordinatensystem und Durchführen einer Kurvenanpassung der Datenpunkte in dem Werkzeugmaschinenkoordinatensystem, um eine angepasste Kurve zu erhalten;
• S112: Diskretisieren der angepassten Kurve in Schritt S111, Erhalten eines diskreten Punkts, Umwandeln des diskreten Punkts in das Werkstückkoordinatensystem und Berechnen des Hausdorff -Abstands zwischen der Kurve in dem Werkstückkoordinatensystem und dem diskreten Punkt;
• S113: Einstellen der angepassten Kurve in Schritt S111, so dass der Hausdorff -Abstand die Fehlerbeschränkung erfüllt;
• S114: Umwandeln der angepassten Kurve in Schritt S113 in eine Zeit-basierten Kurve;
• S115: Feststellen, ob die Zeit-Spline-Kurve in Schritt S114 die dynamische Leistungsbeschränkung jeder Antriebswelle der Werkzeugmaschine erfüllt, wobei die dynamische Leistungsbeschränkung eine Geschwindigkeitsbeschränkung, eine Beschleunigungsbeschränkung und eine Ruckbeschränkung umfasst;

In a further training, step S11 specifically includes the following:

• S111: converting the data points in a workpiece coordinate system into a machine tool coordinate system according to the structural parameters of the machine tool and performing curve fitting of the data points in the machine tool coordinate system to obtain a fitted curve;
• S112: discretizing the fitted curve in step S111, obtaining a discrete point, converting the discrete point into the workpiece coordinate system, and calculating the Hausdorff distance between the curve in the workpiece coordinate system and the discrete point;
• S113: Adjusting the fitted curve in step S111 so that the Hausdorff distance satisfies the error limitation;
• S114: converting the fitted curve into a time-based curve in step S113;
• S115: Determine whether the time spline curve satisfies the dynamic power limitation of each drive shaft of the machine tool in step S114, the dynamic power limitation including a speed limitation, an acceleration limitation and a jerk limitation;

Specifically, in this step, it is assumed that the symbol f(t) represents a curve with time as a parameter, and the dynamic performance constraints include speed constraints, acceleration constraints and jerk constraints, which can be expressed as follows: $$\{\begin{array}{c}\left|f_{\mathrm{\Omega }}^{\text{'}}\left(t\right)\right|\le v_{\mathrm{\Omega }\text{Max}},\\ \left|f_{\mathrm{\Omega }}^{"}\left(t\right)\right|\le v_{\mathrm{\Omega }\text{Max}\text{,}}\\ \left|f_{\mathrm{\Omega }}^{"\text{'}}\left(t\right)\right|\le v_{\mathrm{\Omega }\text{Max}}\end{array}$$

• S116: Verwenden eines Verfahrens zum Erhöhen der Anzahl an Knoten oder zum Reduzieren des Zeitparameterbereichs, wenn die dynamische Leistungsbeschränkung in Schritt S115 nicht erfüllt ist;
• S117: Iterative Optimierung durch Schritt S116, um eine zeitoptimale Zeit-Spline-Kurve zu erhalten, die die dynamische Leistung und den Bearbeitungsfehler erfüllt.

Ω stands for the X, Y, Z, A and C axes, V _Ωmax for the speed limit, A _Ωmax for the acceleration limit, J _Ωmax for the jerk limit, and A, C for two rotation axes. The A axis can be rotated around the X axis and the C axis can be rotated around the Z axis.

• S116: using a method of increasing the number of nodes or reducing the time parameter range if the dynamic power constraint is not satisfied in step S115;
• S117: Iterative optimization through step S116 to obtain a time-optimal time spline curve that satisfies the dynamic performance and machining error.

• Schritt S21: Erhalten einer diskreten Punktspalte P{p_i,j,i = 1,...,m; j = 1,...,n} auf der gesamten diskreten Oberfläche gemäß einem voreingestellten Zeitschritt δt;
• Schritt S22: Durchführen einer Oberflächenrekonstruktion gemäß der diskreten Punktspalte P{p_i,j, i = 1,...,m; j = 1,...,n}, um eine rekonstruierte Oberfläche S(t,d_t,j (t,E)) zu erhalten, so dass sich alle diskreten Punktspalten P{p_i,_j, i = 1,...,m; j = 1,...,n} auf der rekonstruierten Oberfläche S(t,d_t,j (t,E)) befinden und die Fehlerbeschränkung des Hausdorff -Abstands im diskreten Sinne mit der anfänglichen Oberfläche S(u,v) erfüllt.

More specifically, step S2 specifically includes the following:

• Step S21: Obtaining a discrete point column P{p _i,j ,i = 1,...,m; j = 1,...,n} on the entire discrete surface according to a preset time step δt;
• Step S22: Performing a surface reconstruction according to the discrete point column P{p _i,j , i = 1,...,m; j = 1,...,n} to obtain a reconstructed surface S(t,d _t,j (t,E)) such that all discrete point columns P{p _i , _j , i = 1,...,m; j = 1,...,n} are located on the reconstructed surface S(t,d _t,j (t,E)) and the error bound of the Hausdorff distance is satisfied in the discrete sense with the initial surface S(u,v). .

• Schritt S31: Aufzeichnen der einzelnen Zeit-Spline-Kurven r(t)_j, die den diskreten Punktspalten in Schritt S2 entsprechen;
• Schritt S32: Zuordnen der Parameter der Zeit-basierten Spline-Kurve r(t)_j zu denen der rekonstruierten Oberfläche S(t,d_t,j (t,E));
• Schritt S33: Bestimmen des Intervalls der neuen Zeit-Spline-Kurve, nämlich der neuen Bandbreite, basierend auf der Größenbeziehung zwischen der Resthöhenfehlerbeschränkung E_m, die für die tatsächliche Verarbeitung erforderlich ist, und dem voreingestellten Resthöhenfehler E;
• Schritt S34: Bestimmen der Zeit-Spline-Kurve, die in Schritt S1 benachbart zu der neuen Zeit-Spline-Kurve erhalten wird, basierend auf der Intervallgröße der neuen Zeit-Spline-Kurve und Durchführen einer linearen Interpolation gemäß der benachbarten Zeit-Spline-Kurve, die in dem Schritt S1 erhalten wird, um eine neue Zeit-Spline-Kurve zu bestimmen;
• Schritt S35: Optimieren der neuen Zeit-Spline-Kurve, die durch Schritt S34 erhalten wird, so dass der optimierte Werkzeugweg die dynamische Leistung und die Fehlerbeschränkung der Werkzeugmaschine erfüllt.

More specifically, step S3 specifically includes the following:

• Step S31: record the individual time spline curves r(t) _j corresponding to the discrete point columns in step S2;
• Step S32: Assign the parameters of the time-based spline curve r(t) _j to those of the reconstructed surface S(t,d _t,j (t,E));
• Step S33: determining the interval of the new time spline curve, namely the new bandwidth, based on the magnitude relationship between the residual height error restriction E _m required for the actual processing and the preset residual height error E;
• Step S34: Determine the time spline curve obtained in step S1 adjacent to the new time spline curve based on the interval size of the new time spline curve and perform linear interpolation according to the adjacent time spline curve. curve obtained in step S1 to determine a new time spline curve;
• Step S35: Optimize the new time spline curve obtained by Step S34 so that the optimized tool path meets the dynamic performance and error limitation of the machine tool.

In the technical solution of the invention, by using the spline curve tool path with time as a parameter, the interpolation calculation can be carried out directly according to the time parameter based on the satisfaction of the machining error and the dynamic power limitation of the machine tool, improving the calculation speed of the curve interpolation and meeting the real-time requirement of the curve interpolation of the CNC System can be realized and the properties of high precision and high speed are achieved. In addition, when generating the tool path, the corresponding bandwidth can be adaptively generated under different residual error constraints according to the geometric parameters of the other direction of the surface, thereby improving the calculation speed of tool path generation. Regarding tool path generation in the present invention, the work of speed planning in the CNC system is combined. Thus, tool path generation and speed planning can be combined with each other, which not only reduces the computational complexity of tool path generation, but also effectively improves the calculation efficiency of the speed planning algorithm, thereby meeting the final high-speed and high-machining requirement.

• ein Zeit-Spline-Kurvenerzeugungsmodul 602 zum Voreinstellen eines Resthöhenfehlers E, zum Bestimmen einer ersten Anzahl von Werkzeugwegen auf einer anfänglichen Oberfläche S(u,v) basierend auf der Beschränkung E_m des Resthöhenfehlers E und zum Umwandeln jedes der ersten Anzahl von Werkzeugwegen in eine Zeit-Spline-Kurve, um die erste Anzahl von Zeit-Spline-Kurven zu erhalten;
• ein Oberflächenrekonstruktionsmodul 604 zum Diskretisieren der ersten Anzahl von Zeit-Spline-Kurven in eine Punktspalte gemäß einem voreingestellten Zeitschritt und zum Durchführen einer Oberflächenrekonstruktion an der Punktspalte, um eine Oberfläche mit Zeit- und Resthöhenfehlern als Parameter zu erhalten;
• ein Werkzeugentfernungserzeugungsmodul 606 zum Erzeugen eines Werkzeugweges für die Oberfläche mit Zeit- und Resthöhenfehlern als Parameter gemäß der Resthöhenfehlerbeschränkung E_m der Bearbeitungsanforderungen,

wobei eine Zeit-Spline-Kurve, die die Resthöhenfehlerbeschränkung E_m und die dynamische Leistungsbeschränkung der Werkzeugmaschine erfüllt, als Werkzeugweg verwendet wird, wie ferner in den Ansprüchen definiert.Based on the same idea, an embodiment of the description further provides an apparatus corresponding to the above method. 6 shows a schematic structural representation of one of the 1 corresponding device for generating a CAM-oriented time spline curve and surface according to the technical solution of the exemplary embodiment of the present description. As in 6 shown, the device includes the following:

• a time spline curve generation module 602 for presetting a residual height error E, determining a first number of toolpaths on an initial surface S(u,v) based on the constraint E _m of the residual height error E, and converting each of the first number of toolpaths into one Time spline curve to get the first number of time spline curves;
• a surface reconstruction module 604 for discretizing the first number of time spline curves into a point column according to a preset time step and performing surface reconstruction on the point column to obtain a surface with time and residual height errors as parameters;
• a tool distance generation module 606 for generating a tool path for the surface with time and residual height errors as parameters according to the residual height error constraint E _m of the machining requirements,

wherein a time spline curve satisfying the residual height error constraint E _m and the dynamic power constraint of the machine tool is used as a tool path, as further defined in the claims.

It should be understood that although the terms "first", "second", "third", etc. may be used in the present application to describe various information, such information should not be limited to these terms. These terms are only used to distinguish the same type of information from each other.

Claims (3)

Method for generating a CAM-oriented time spline curve and surface, characterized in that it comprises the following steps: Step S1: presetting a residual height error E, determining a first number of toolpaths on the initial surface S (u, v) based on the constraint E _m of the residual height error E and converting each of the first number of toolpaths into a time spline curve to obtain the first number of time spline curves, wherein step S1 specifically comprises step S11: converting an initial one Parameter curve S(u,v) according to the dynamic performance of the machine tool and the machining error limitation into a time-based curve r ₀ (t) based on the initial surface r ₀ (u)| _v=0 ; Step S12: Calculate a bandwidth d _t,j (t,E) (where j = 1,2,...,n) that satisfies the residual height error constraint E _m in the parameter direction v using the curve r ₀ (u) | _v=0 as initial curve; Step S13: Calculate a tool path r _j that has the curve r ₀ (u) | _v=0 is used as the initial tool trajectory and the residual height error constraint E _m is satisfied, according to the bandwidth d _t,j (t,E); Converting the tool path r _j into a time-based curve r(t) _j according to the dynamic performance of the machine tool and the machining error limitation; Step S14: Repeat step S13 until the entire surface of the initial surface S(u,v) is covered; Step S2: Discretizing the first number of time spline curves into a point column according to a preset time step and performing a surface reconstruction for the point column to obtain a surface with time and residual height error E as parameters, wherein step S2 specifically comprises step S21: Obtaining a discrete point column P{p _i,j , i = 1,...,m; j = 1,...,n} on the entire discrete surface according to a preset time step δt; Step S22: Perform a surface reconstruction according to the discrete point column P{p _i,j , i = 1,...,m;j = 1,...,n} to obtain a reconstructed surface S( _t ,d _t,j (t,E)) so that all discrete point columns P{p _i,j , i =1,...,m; j =1,...,n} are located on the reconstructed surface S(t,d _t,j (t,E)) and the error bound of the Hausdorff distance is satisfied in the discrete sense with the initial surface S(u,v). ; Step S3: Generate a tool path for the surface with time and residual height error E as parameters according to the residual height error constraint E _m of the machining requirements, and use a time spline curve that satisfies the residual height error constraint E _m and the dynamic power constraint of the machine tool as a tool path, where the Step S3 specifically includes step S31: recording the individual time spline curves r(t) _j corresponding to the discrete point columns in step S2; Step S32: Assign the parameters of the time-based spline curve r(t) _j to those of the reconstructed surface S( _t ,d _t,j (t,E)); Step S33: Determine the interval of the new time spline curve based on the magnitude relationship between the residual height error restriction E _m required for the actual processing and the preset residual height error E; Step S34: Determine the time spline curve obtained in step S1 adjacent to the new time spline curve based on the interval size of the new time spline curve and perform linear interpolation according to the adjacent time spline curve. curve obtained in step S1 to determine a new time spline curve; Step S35: Optimize the new time spline curve obtained by Step S34 so that the optimized tool path meets the dynamic performance and error limitation of the machine tool. Method for generating a CAM-oriented time spline curve and surface according to Claim 1 , characterized in that step S11 specifically comprises: S111: converting the data points in a workpiece coordinate system according to the structural parameters of the machine tool into a machine tool coordinate system and performing curve fitting of the data points in the machine tool coordinate system to obtain a fitted curve; S112: discretizing the fitted curve in step S111, obtaining a discrete point, converting the discrete point into the workpiece coordinate system, and calculating the Hausdorff distance between the curve in the workpiece coordinate system and the discrete point; S113: Adjusting the fitted curve in step S111 so that the Hausdorff distance satisfies the error limitation; S114: converting the fitted curve into a time-based curve in step S113; S115: Determine whether the time spline curve satisfies the dynamic power limitation of each drive shaft of the machine tool in step S114, the dynamic power limitation including a speed limitation, an acceleration limitation and a jerk limitation; S116: Using a method to increase the number of nodes or reduce the time parameter range when the dynamic power power restriction is not met in step S115; S117: Iterative optimization through step S116 to obtain a time-optimal time spline curve that satisfies the dynamic performance and machining error. Apparatus for generating a CAM-oriented time spline curve and surface, characterized in that it comprises: a time spline curve generation module for presetting a residual height error E, for determining a first number of toolpaths on an initial surface S (including , v) based on the constraint E _m of the residual height error E and for converting each of the first number of toolpaths into a time spline curve to obtain the first number of time spline curves, the time spline curve generation module being concrete a module for converting an initial parameter curve S(u,v) according to the dynamic performance of the machine tool and the machining error limitation into a time-based curve r ₀ (t) based on the initial surface r ₀ (u) | _v=0 ; to calculate a bandwidth d _t,j (t,E) (where j = 1,2,...,n) that satisfies the residual height error constraint E _m in the parameter direction v using the curve r ₀ (u) | _v=0 as initial curve; to calculate a toolpath r _j that has the curve r ₀ (u) | _v=0 is used as the initial tool trajectory and the residual height error constraint E _m is satisfied, according to the bandwidth d _t,j (t,E); for converting the tool path r _j into a time-based curve r(t) _j according to the dynamic performance of the machine tool and the machining error limitation; and repeating the transformation of the tool path r _j until the entire surface of the initial surface S(u, v) is covered; a surface reconstruction module for discretizing the first number of time spline curves into a point column according to a preset time step and performing surface reconstruction on the point column to obtain a surface with time and residual height errors E as parameters, the surface reconstruction module specifically comprising a module to obtain a discrete point column P{p _i,j , i = 1,...,m; j = 1,...,n} on the entire discrete surface according to a preset time step δt; and to perform surface reconstruction according to the discrete point column P{p _i,j , i = 1,...,m; j = 1,...,n} to obtain a reconstructed surface S( _t ,d _t,j (t,E)) such that all discrete point columns P{p _i,j , i = 1,. ..,m; j = 1,...,n} are located on the reconstructed surface S(t,d _t,j (t, E)) and the error bound of the Hausdorff distance is satisfied in the discrete sense with the initial surface S(u, v). ; a tool distance generation module for generating a toolpath for the surface with time and residual height errors E as parameters according to the residual height error constraint E _m of the machining requirements, using a time spline curve that satisfies the residual height error constraint E _m and the dynamic power constraint of the machine tool as a tool path , wherein the tool distance generation module specifically comprises a module for recording the individual time spline curves r(t) _j corresponding to the discrete point columns of the surface reconstruction module; for mapping the parameters of the time-based spline curve r(t) _j to those of the reconstructed surface S( _t ,d _t,j (t,E)); for determining the interval of the new time spline curve based on the magnitude relationship between the residual height error constraint E _m required for the actual processing and the preset residual height error E; for determining the time spline curve obtained in the curve generation module adjacent to the new time spline curve based on the interval size of the new time spline curve and performing linear interpolation according to the adjacent time spline curve, obtained in the curve generation module to determine a new time spline curve; to optimize the new time spline curve obtained by the tool distance generation module so that the optimized tool path meets the dynamic performance and error limitation of the machine tool.

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