CN113721551A

CN113721551A - Numerical control machining method and numerical control machining equipment

Info

Publication number: CN113721551A
Application number: CN202010456287.4A
Authority: CN
Inventors: 朱志浩; 朱蓓; 赵建华; 邱明勇; 杨锦涛; 邹志强
Original assignee: Symg Shanghai Intelligence System Co ltd
Current assignee: Symg Shanghai Intelligence System Co ltd
Priority date: 2020-05-26
Filing date: 2020-05-26
Publication date: 2021-11-30

Abstract

The invention provides a numerical control machining method and numerical control machining equipment, wherein the method comprises the following steps: 1) continuous micro-segment identification: identifying a continuous micro-segment part needing smooth compression according to the length and the vector angle between the programming points of the program segment to be processed; 2) and (3) node vector parameterization: parameterizing a programming point for a continuous micro-segment part needing smooth compression to obtain a node vector parameter corresponding to the programming point; 3) solving the first order tangent vector: constructing an interpolation curve through continuous 4 programming points to calculate a first tangent vector corresponding to the programming points; 4) smooth compression program segment: compressing the programming points into spline curves according to the programming point instruction values of the continuous micro-segments to be smoothly compressed and the corresponding first-order tangent vector values; and checking whether the Euclidean distance from the programming point to the corresponding spline point meets the machining precision or not, and correspondingly adjusting the control point to carry out error control. The numerical control machining method and the numerical control machining equipment are used for smoothing the machining track within the precision range.

Description

Numerical control machining method and numerical control machining equipment

Technical Field

The invention relates to the technical field of numerical control machining, in particular to a numerical control machining method and numerical control machining equipment.

Background

In the numerical control machine tool machining, the free curves and the free curved surfaces have been widely used in the die machining, the automobile part machining and the aviation part machining. However, fast high quality machining of free curves and surfaces has been a difficult point in machining. In the conventional machining of a free curve or a curved surface of a numerical control system, a large number of tiny straight line segments are generally approximated by a large number of tiny line segments by CAM (Computer-aided manufacturing) software, and then the numerical control system machines the large number of tiny straight line segments, which are generated by the CAM software approximating the designed free curve or the curved surface, according to a straight line interpolation method (G01 method).

When the CAM software is used for processing, if the tolerance setting is large (such as +/-0.03), the CAM software adopts a tiny line segment to approach a designed free curve or curved surface, the effect is poor, and then the processing is carried out according to a G01 mode, so that the processed workpiece surface has inclined planes, ripples, stripes and the like, and the surface quality cannot meet the requirements. If the tolerance setting is small (e.g., +/-0.001), the amount of program data generated by the CAM software is very large, which may consume a lot of computer resources. And the length of a tiny line segment for approaching a free-form curved surface or a curve is too small, and the acceleration of each axis is frequently changed due to the adoption of a linear interpolation mode of a numerical control system, so that the vibration of a machine tool is caused, and the surface quality of a machined workpiece is finally influenced.

Chinese patent CN101881952B discloses a method for smooth compression of program segment suitable for numerical control devices, which can avoid the uneven surface of the workpiece caused by linear interpolation at the transition of the program segment, but the processing precision is not precisely controllable.

Therefore, it is desirable to solve the problem that the precision and efficiency of the conventional micro-segment smoothing compression processing method for numerical control machining cannot meet the production requirements.

Disclosure of Invention

In view of the above-mentioned shortcomings of the prior art, the present invention aims to provide a numerical control machining method and a numerical control machining device, which are used for solving the problem that the precision and efficiency of the micro-segment smooth compression processing method for numerical control machining in the prior art cannot meet the production requirement.

In order to achieve the above objects and other related objects, the present invention provides a method for digitally processing a communication signal, comprising the steps of: providing a machining program curve P required by numerical control machining equipment₀P_nSaid machining program curve P₀P_nComprises at least two micro-segment instruction points P_iAnd P_j(ii) a Identifying successive micro-segment portions P_i P_j(ii) a The continuous micro-segment part P_i P_jObtaining a target processing curve according to the deviation range: if the continuous micro-segment portion P_i P_jCan be smoothly compressed into a spline curve meeting the processing precision, i.e. form a continuous micro-segment part P_i P_jA corresponding target processing curve; if a continuous micro-segment portion P_i P_jCan not be smoothly compressed into a spline curve meeting the processing precision, and j is reduced to k until a continuous micro-segment part P_i P_kCan be smoothly compressed into a spline curve meeting the processing precision, and then the continuous micro-segment part P is obtained_i P_kCorresponding sub-target processing curves; the remaining micro-segment portion P is then compressed smoothly in the same manner_k P_jTo obtain a remaining micro-segment portion P_k P_jProcessing curves of the sub-targets corresponding to the instruction points; all the sub-target processing curves are connected in sequence to obtain a continuous micro-segment part P_i P_jThe target machining curve of (1); wherein, P_iFor the machining program curve P₀P_nAnd k is more than or equal to i and j is more than or equal to m at any micro-segment instruction point, and the j is a positive integer.

In an embodiment of the present invention, the continuous micro-segment P is obtained_i P_jAfter the target machining curve is obtained, the numerical control machining equipment machines the workpiece according to the target machining curve.

In an embodiment of the invention, the identification of the continuous micro-segment portion P_i P_jThe method comprises the following steps: curve P of the machining program₀P_mUpper adjacent two micro-segment instruction point P_n，P_n+1Length between and a preset micro-segment length threshold d_maxComparing, if the length between the two adjacent instruction points is greater than the threshold d of the micro-segment length_maxThen the corresponding two micro-segment instruction points P are set_n，P_n-1Set as the break-off point of the continuous micro-segment; three adjacent micro-segment instruction points P_n-1，P_n，P_n+1Formed vector angle P_n-1P_nP_n+1Comparing the vector angle with a preset angle threshold value, and if the vector angle is larger than the angle threshold value, enabling a programming point P corresponding to the intersection point of the vector angle_nSet as the break-off point of the continuous micro-segment; a starting point P₀And a disconnection point P adjacent thereto_nEnd point P_mAnd a disconnection point P adjacent thereto_n+1Or a continuous micro-segment portion between two adjacent disconnection points is identified as the continuous micro-segment portion P_i P_jWherein n and m are positive integers, and n is more than i and less than or equal to m or n is more than j and less than or equal to m.

In an embodiment of the present invention, the continuous micro-segment portion P is divided into two portions_i P_jThe step of smooth compression into a spline curve satisfying the machining accuracy includes: obtaining and said continuous micro-segment portion P_i P_jNode vector parameters corresponding to the micro-segment instruction points on the micro-segment instruction points; through said continuous micro-segment portion P_i P_jConstructing an interpolation curve by the upper continuous 4 micro-segment command points to calculate a first tangent vector corresponding to the 4 micro-segment command points; according to the continuous micro-segment part P_i P_jA micro-segment instruction point, a node vector parameter corresponding to the micro-segment instruction point, and a continuous micro-segment part P_i P_jA first tangent vector corresponding to the continuous 4 micro-segment command points on the surface of the substrate, and a continuous micro-segment part P_i P_jCompressed into a first order continuous smooth spline curve.

In an embodiment of the present invention, the method for obtaining node vector parameters includes: according to the chord length delta P between two adjacent micro-segment command points_iVector angle P formed by the instruction points of three adjacent micro-segments_i-1P_iP_i+1To obtain and micro-segment instruction point P_iCorresponding node vector parameter u_i。

In one embodiment of the present invention, the continuous micro-segment portion P is passed through_i P_jThe step of constructing an interpolation curve for the upper continuous 4 micro-segment command points to calculate a first tangent vector corresponding to the 4 micro-segment command points includes: according to successive micro-segment instruction points P_i-2、P_i-1、P_i、P_i+1、P_i+2And the node vector parameter value u corresponding to each instruction point_i-2、u_i-1、u_i、u_i+1、u_i+2Constructing 4 micro-segment instruction points P respectively passing through_i-2、P_i-1、P_iAnd P_i+1Of a cubic polynomial interpolation curve Q_i-2(u) and passing through 4 consecutive instruction points P of said micro-segment_i-1、P_i、P_i+1And P_i+2Of a cubic polynomial interpolation curve Q_i-1(u); solving two cubic polynomial interpolation curves Q_i-2(u)、Q_i-1(u) at the micro-segment instruction point P_iFirst order tangent vector Q'_i-2(u_i)、Q'_i-1(u_i) (ii) a The obtained micro-segment command point P_iFirst order tangent vector Q'_i-2(u)、Q'_i-1(u) average value as the micro-segment instruction point P_iCorresponding first order tangent vector value T_i。

In an embodiment of the present invention, the continuous micro-segment portion P_i P_jThe step of compressing into the first order continuous smooth spline curve satisfying the machining accuracy includes: calculating the starting point P of the continuous micro-segment part to be smoothly compressed_iAnd a termination point P_jControl point G of the curve in between₁And G₂(ii) a Obtaining a curve control point G₁And G₂Correspondingly fitting a cubic Bezier curve; adjusting the curve control point G according to the machining error₁And G₂And adjusting and fitting the cubic Bezier curve to obtain the first-order continuous smooth spline curve meeting the processing precision.

In one embodiment of the present invention, the computing microSegment instruction point P_iAnd P_jThe method of curve control point in between comprises: when the micro-segment instruction point P_iAnd P_jIs a non-adjacent micro-segment instruction point, and P_i、P_j、T_i、T_jWhen the planes are coplanar, calculating and sequentially approaching micro-segment instruction points P according to a least square method_kCurve control point G of_k1And G_k2Wherein the micro-segment instruction point P_kFor instruction point P of micro-segment_iAnd P_jMicro-segment instruction points in between.

In an embodiment of the present invention, the computation micro-segment instruction point P_iAnd P_jThe method of curve control point in between comprises: when the micro-segment instruction point P_iAnd P_jIs a non-adjacent micro-segment instruction point, and P_i、P_j、T_i、T_jWhen not coplanar, sequentially calculating instruction points P passing through micro-segment_kCurve control point G of_k1Coefficient parameter alpha and curve control point G_k2The coefficient parameter β of (a); when alpha > 0 and beta < 0, a curve control point G is calculated from the coefficient parameters alpha and beta₁And G₂(ii) a When alpha is less than or equal to 0 or beta is greater than or equal to 0, making j reduce by 1, if j is>i +1, calculating a curve control point G according to the coefficient parameters alpha and beta₁And G₂(ii) a If j is i +1, the control point G is directly calculated₁And G₂。

In an embodiment of the present invention, the step of adjusting the curve control point according to the machining error includes: when the micro-segment instruction point P_iAnd P_jWhen the instruction points are non-adjacent micro-segment instruction points, calculating the obtained curve control point G_k1And G_k2Mean value G of₁And G₂(ii) a Calculate by P_i、G₁、G₂、P_jThe deviation delta E of the fitted cubic Bezier curve of the control points; judging whether the deviation delta E is smaller than a preset deviation E or not, and if so, taking P as the deviation delta E_i、G₁、G₂、P_jFitting cubic Bezier curves for the control points to serve as the first-order continuous smooth spline curve meeting the machining precision; when the deviation delta E is larger than or equal to the preset deviation E, j is made to be j-1, and then P is recalculated_iAnd P_jControl point G of the curve in between₁And G₂。

In an embodiment of the present invention, the continuous micro-segment portion P_i P_jCompressing into a first-order continuous smooth spline when the instruction point P is a micro-segment_iAnd P_jWhen the instruction points are adjacent micro-segment instruction points, namely j ═ i +1, the curve control point G is directly calculated₁And G₂To obtain a fitting curve C_t(u) and fitting the curve C_t(u) as a continuous micro-segment P_i P_jThe corresponding target curve.

In order to achieve the above object, the present invention further provides a numerical control machining apparatus for communication signals, including: a processing program curve providing module suitable for providing a processing program curve P required by the numerical control processing equipment₀P_nSaid machining program curve P₀P_nComprises at least two micro-segment instruction points P_i(ii) a A continuous micro-segment recognition module adapted to recognize a continuous micro-segment part P_iP_j(ii) a A target processing curve module comprising a smoothing compression unit adapted to compress said continuous micro-segment portion P_iP_jObtaining a target processing curve according to the deviation range: if the continuous micro-segment portion P_iP_jCan be smoothly compressed into a spline curve meeting the processing precision, i.e. form a continuous micro-segment part P_iP_jA corresponding target processing curve; a smooth compression unit adapted to compress the continuous micro-segment portion P_iP_jWhen the sample curve which can not be smoothly compressed and meets the processing precision is obtained, j is reduced to k until the continuous micro-segment part P_iP_kCan be smoothly compressed into a spline curve meeting the processing precision, and then the continuous micro-segment part P is obtained_iP_kCorresponding sub-target processing curves; the smoothing compression unit is further adapted to smooth-compress the remaining micro-segment portion P again in the same manner_k P_jTo obtain a remaining micro-segment portion P_k P_jProcessing curves of the sub-targets corresponding to the instruction points; the target processing curve module is also suitable for connecting all sub-target curves in sequence to obtain a continuous micro-segment part P_iP_jTarget processing koji ofA wire; wherein, P_iFor the machining program curve P₀P_nAnd k is more than or equal to i and j is more than or equal to m at any micro-segment instruction point, and the j is a positive integer.

In an embodiment of the invention, the numerical control machining apparatus machines the workpiece according to the target machining curve.

In an embodiment of the present invention, the continuous micro-segment identification module includes: a length comparison unit adapted to compare the machining program curve P₀P_mUpper adjacent two micro-segment instruction point P_n，P_n+1Length between and a preset micro-segment length threshold d_maxComparing, if the length between the two adjacent instruction points is greater than the threshold d of the micro-segment length_maxThen the corresponding two micro-segment instruction points P are set_n，P_n-1Set as the break-off point of the continuous micro-segment; an angle comparison unit suitable for comparing the adjacent three micro-segment command points P_n-1，P_n，P_n+1Formed vector angle P_n-1P_nP_n+1Comparing the vector angle with a preset angle threshold value, and if the vector angle is larger than the angle threshold value, determining a micro-segment instruction point P corresponding to the intersection point of the vector angle_nSet as the break-off point of the continuous micro-segment; an identification unit adapted to identify a start/end point and an adjacent break point or a continuous micro-segment portion between two adjacent break points as the continuous micro-segment portion P_iP_jStarting point P₀And a disconnection point P adjacent thereto_nEnd point P_mAnd a disconnection point P adjacent thereto_n+1Or a continuous micro-segment portion between two adjacent disconnection points is identified as the continuous micro-segment portion P_iP_jWherein n and m are positive integers, and n is more than i and less than or equal to m or n is more than j and less than or equal to m.

In an embodiment of the invention, the smooth compression unit includes: a node vector parameter component adapted to obtain a vector of parameters associated with said continuous micro-segment portion P_iP_jNode vector parameters corresponding to the micro-segment instruction points on the micro-segment instruction points; a first order sagittal assembly adapted to pass through said continuous micro-segment portion P_iP_jConstructing interpolation curve for the upper continuous 4 micro-segment command points to calculate one corresponding to the 4 micro-segment command pointsStep tangent vector; a spline curve generation component for generating a spline curve from the continuous micro-segment portion P_iP_jA micro-segment instruction point, a node vector parameter corresponding to the micro-segment instruction point, and a continuous micro-segment part P_iP_jA first tangent vector corresponding to the continuous 4 micro-segment command points on the surface of the substrate, and a continuous micro-segment part P_iP_jCompressed into a first order continuous smooth spline curve.

In an embodiment of the invention, the node vector parameter component is adapted to be based on a chord length Δ P between two adjacent instruction points of the micro-segment_iVector angle P formed by the instruction points of three adjacent micro-segments_i-1P_iP_i+1To obtain and micro-segment instruction point P_iCorresponding node vector parameter u_i。

In an embodiment of the present invention, the first tangent vector component includes: a binomial interpolation curve part suitable for the instruction point P of continuous micro-segment_i-2、P_i-1、P_i、P_i+1、P_i+2And the node vector parameter value u corresponding to each instruction point_i-2、u_i-1、u_i、u_i+1、u_i+2Constructing 4 micro-segment instruction points P respectively passing through_i-2、P_i-1、P_iAnd P_i+1Of a cubic polynomial interpolation curve Q_i-2(u) and passing through 4 consecutive instruction points P of said micro-segment_i-1、P_i、P_i+1And P_i+2Of a cubic polynomial interpolation curve Q_i-1(u); a one-order vector cutting component of the micro-segment instruction point, which is suitable for solving the two cubic polynomial interpolation curves Q_i-2(u)、Q_i-1(u) at the micro-segment instruction point P_iFirst order tangent vector Q'_i-2(u_i)、Q'_i-1(u_i) (ii) a A first tangent vector averaging part adapted to average the obtained micro-segment command point P_iFirst order tangent vector Q'_i-2(u)、Q'_i-1(u) average value as the micro-segment instruction point P_iCorresponding first order tangent vector value T_i。

In an embodiment of the present invention, the spline curve generating component includes: control point calculating unit, and control point calculating methodFor calculating the starting point P of the continuous micro-segment portion to be smoothly compressed_iAnd a termination point P_jControl point G of the curve in between₁And G₂(ii) a A Bezier curve acquisition unit adapted to acquire and curve control points G₁And G₂Correspondingly fitting a cubic Bezier curve; a machining error control part adapted to let the control point calculation unit adjust the curve control point G according to a machining error₁And G₂And adjusting and fitting the cubic Bezier curve to obtain the first-order continuous smooth spline curve meeting the processing precision.

In an embodiment of the present invention, the control point calculating unit includes: a first calculation unit adapted to calculate a micro-segment command point P_iAnd P_jIs a non-adjacent micro-segment instruction point, and P_i、P_j、T_i、T_jWhen the planes are coplanar, calculating and sequentially approaching micro-segment instruction points P according to a least square method_kCurve control point G of_k1And G_k2Wherein the micro-segment instruction point P_kFor instruction point P of micro-segment_iAnd P_jMicro-segment instruction points in between.

In an embodiment of the present invention, the curve control point calculating unit includes: a control point coefficient calculating unit adapted to calculate a control point coefficient when the micro-segment command point P is detected_iAnd P_jIs a non-adjacent micro-segment instruction point, and P_i、P_j、T_i、T_jWhen not coplanar, sequentially calculating instruction points P passing through micro-segment_kCurve control point G of_k1Coefficient parameter alpha and curve control point G_k2The coefficient parameter β of (a); a second calculation unit adapted to calculate a curve control point G based on the coefficient parameters alpha and beta when alpha > 0 and beta < 0₁And G₂(ii) a A third calculation unit adapted to, when alpha ≦ 0 or beta ≧ 0, the compression unit adapted to self-subtract j by 1, then j by 1, if j is>i +1, calculating a curve control point G according to the coefficient parameters alpha and beta₁And G₂(ii) a If j is i +1, the control point G is directly calculated₁And G₂。

In an embodiment of the present invention, the machining error control unit includes: a control point mean value calculation unit suitable for micro-segment fingerOrder point P_iAnd P_jWhen the instruction points are non-adjacent micro-segment instruction points, calculating the obtained curve control point G_k1And G_k2Mean value G of₁And G₂(ii) a A deviation calculation unit adapted to calculate P_i、G₁、G₂、P_jThe deviation delta E of the fitted cubic Bezier curve of the control points; an adjusting unit adapted to adjust the deviation Delta E by P when the deviation Delta E is smaller than a preset deviation E_i、G₁、G₂、P_jFitting cubic Bezier curves for the control points to serve as the first-order continuous smooth spline curve meeting the machining precision; when the deviation delta E is larger than or equal to the preset deviation E, a fourth curve control point calculating component is adopted, the fourth curve control point calculating component is suitable for enabling j to be j-1, and then P is recalculated_iAnd P_jControl point G of the curve in between₁And G₂。

In an embodiment of the invention, the smooth compression unit further comprises a fifth curve control point calculating component, and the fifth curve control point calculating component is adapted to calculate the control point P at the micro-segment command point P_iAnd P_jWhen the instruction points are adjacent micro-segment instruction points, namely j ═ i +1, curve control points are directly calculated to obtain a fitting curve C_t(u) and fitting the curve C_t(u) as a continuous micro-segment P_i P_jThe corresponding target curve.

As described above, the numerical control machining method and the numerical control machining apparatus of the present invention have the following advantageous effects: the smooth machining track in the precision range can be improved.

Drawings

FIG. 1 is a flowchart of a numerical control machining method according to an embodiment of the present invention;

FIG. 2A is a continuous micro-segment judgment diagram (I) in an embodiment of the numerical control machining method of the present invention;

FIG. 2B is a continuous micro-segment judgment diagram (II) in another embodiment of the numerical control machining method of the present invention;

FIG. 3 is a flow chart of continuous micro-segment target curve fitting in one embodiment of the numerical control machining method of the present invention;

FIG. 4A is a schematic diagram illustrating a control point calculation in an embodiment of the numerical control machining method of the present invention;

FIG. 4B is a schematic diagram of the calculation of control points in another embodiment of the numerical control machining method of the present invention;

FIG. 5 is a diagram illustrating simulation effects of the numerical control machining method according to an embodiment of the present invention;

FIG. 6A is a machined surface of a workpiece without the use of the present numerically controlled machining method;

FIG. 6B is a machined surface of a workpiece using the numerical control machining method of the present invention;

FIG. 7 is a schematic structural diagram of a CNC machining system according to an embodiment of the present invention.

Description of the element reference numerals

71 processing program curve providing module

72 continuous micro-segment identification module

73 target processing curve module

Detailed Description

The embodiments of the present invention are described below with reference to specific embodiments, and other advantages and effects of the present invention will be easily understood by those skilled in the art from the disclosure of the present specification. The invention is capable of other and different embodiments and of being practiced or of being carried out in various ways, and its several details are capable of modification in various respects, all without departing from the spirit and scope of the present invention. It is to be noted that the features in the following embodiments and examples may be combined with each other without conflict.

It should be noted that the drawings provided in the following embodiments are only for illustrating the basic idea of the present invention, so that the components related to the present invention are only shown in the drawings rather than drawn according to the number, shape and size of the components in actual implementation, the type, quantity and proportion of the components in actual implementation can be changed freely, and the layout of the components can be more complicated.

The numerical control processing method and the numerical control processing equipment are used for providing the micro-segment smooth compression processing method for numerical control processing, which can meet the production requirements in terms of precision and efficiency.

As shown in fig. 1, the method of the present invention comprises the steps of:

step (I), continuous micro-segment identification: and identifying the part of the workpiece needing smooth compression through the length of the line segment to be processed and the vector angle information between the line segments.

And (II) parameterizing a node vector: and (3) parameterizing the programming point by combining the relation between the length and the angle of the continuous micro-segment part needing smooth compression, and acquiring the node vector parameter corresponding to the programming point.

Solving a first-order tangent vector: and solving the first-order tangent vector by adopting a four-point construction method, constructing a cubic polynomial by continuous 4 programming points, and solving the first-order tangent vector of the corresponding point.

Step (four), requiring internal smooth compression program segment with precision: according to the instruction value of the continuous micro-segment programming point to be smoothly compressed and the corresponding first-order tangent vector, a broken line track described by the programming point is compressed into a first-order continuous smooth curve; and checking whether the Euclidean distance between the programming point and the corresponding spline point (the spline curve value corresponding to the node vector parameter value obtained by calculating the programming point) meets the processing precision, and adjusting the control point of the spline curve to carry out error control on the spline curve which does not meet the requirement.

The numerical control processing method of the communication signal comprises the following steps:

step 100, providing a machining program curve P required by the numerical control machining equipment₀P_nSaid machining program curve P₀P_nComprises at least two micro-segment instruction points P_iAnd P_j。

Step 200, identifying a continuous micro-segment part P_i P_j。

Step 300, the continuous micro-segment part P_i P_jAnd obtaining a target processing curve according to the deviation range.

In particular, if the continuous micro-segment portion P_i P_jCan be smoothly compressed into a spline curve meeting the processing precision, i.e. form a continuous micro-segment part P_i P_jCorresponding target processing curve.

If a continuous micro-segment portion P_i P_jCan not be smoothly compressed into a spline curve meeting the processing precision, and j is reduced to k until a continuous micro-segment part P_i P_kCan be smoothly compressed into a spline curve meeting the processing precision, and then the continuous micro-segment part P is obtained_i P_kThe corresponding sub-target processing curve.

Step 400, the remaining micro-segment P is compressed smoothly in the same way_k P_jTo obtain a remaining micro-segment portion P_kP_jAnd (5) processing curves of the sub-targets corresponding to the instruction points.

Step 500, connecting all sub-target processing curves in sequence to obtain a continuous micro-segment part P_i P_jThe target processing curve of (1).

Specifically, wherein, P_iFor the machining program curve P₀P_nAnd k is more than or equal to i and j is more than or equal to m at any micro-segment instruction point, and the j is a positive integer.

The following embodiments of the numerical control machining method provided by the present invention are described in detail with specific examples, and it should be understood by those skilled in the art that the following embodiments are not intended to limit the scope of the present invention, which is within the scope of the present invention in other similar machining environments, or in other similar apparatuses or similar methods.

In a specific embodiment, the numerical control machining device may be a numerical control lathe, a vertical machining center, a five-axis linkage machine tool, or the like.

Specifically, a processing drawing formed by drawing software is adopted. Generally, two-dimensional graphics can be formed by CAD, and three-dimensional graphics can be formed by Pro/E, inventor, solidworks and other software. The curve to be processed is the outline of a two-dimensional workpiece figure or the outline of a cross-sectional figure of a three-dimensional workpiece figure.

The processing program curve is a curve obtained by carrying out micro-line segment differentiation on a curve of a free-form surface to be processed in a drawing by computer aided manufacturing software according to a processing drawing. The micro-segment instruction point is a point at which the machining program curve is subdivided into micro-segments (hereinafter referred to as "micro-segments").

Step 200, identifying a continuous micro-segment part P_i P_j。

Wherein the step 200 identifies a continuous micro-segment portion P_i P_jThe method comprises the following steps:

step 201 is executed: curve P of the machining program₀P_mUpper adjacent two micro-segment instruction point P_n，P_n+1Length between and a preset micro-segment length threshold d_maxComparing, if the length between the two adjacent instruction points is greater than the threshold d of the micro-segment length_maxThen the corresponding two micro-segment instruction points P are set_n，P_n-1Set as the break-off point for the continuous micro-segment.

As shown in fig. 2A, a method of determining a continuous micro segment will be described by way of example. Program segment P_i-1P_iAnd P_i+6P_i+7The length is larger than the micro-segment length d of the system setting_max(d in this example)_max2mm), program segment P_iP_i+1、P_i+1P_i+2、P_i+2P_i+3、P_i+ ₃P_i+4、P_i+4P_i+5、P_i+5P_i+6And P_i+6P_i+7The lengths of the micro-segments are all less than the length d of the micro-segment_max. Program segment P_iP_i+1、P_i+1P_i+2、P_i+2P_i+3、P_i+ ₃P_i+4、P_i+4P_i+5And P_i+5P_i+6In addition to the program segment P_i+2P_i+3And P_i+3P_i+4Vector angle of (theta)_i+3Greater than the maximum rotation angle theta set by the system_max(in this example,. theta._max30 °), others are less than θ_max. At this time, the program segment P is inferred_iP_i+1、P_i+1P_i+2、P_i+2P_i+3Is a continuous micro-segment; program segment P_i+3P_i+4、P_i+4P_i+5、P_i+5P_i+6Are continuous micro-segments.

Step 202 is executed: three adjacent micro-segment instruction points P_n-1，P_n，P_n+1Formed vector angle P_n-1P_nP_n+1Comparing the vector angle with a preset angle threshold value, and if the vector angle is larger than the angle threshold value, enabling a programming point P corresponding to the intersection point of the vector angle_nSet as the break-off point for the continuous micro-segment.

As shown in fig. 2B, a program segment P_i-1P_iAnd P_i+6P_i+7The length is larger than the micro-segment length d of the system setting_maxProgram segment P_iP_i+1、P_i+1P_i+2、P_i+2P_i+3、P_i+3P_i+4、P_i+4P_i+5、P_i+5P_i+6And P_i+6P_i+7The lengths of the micro-segments are all less than the length d of the micro-segment_max. Program segment P_iP_i+1、P_i+1P_i+2、P_i+2P_i+3、P_i+3P_i+4、P_i+4P_i+5And P_i+5P_i+6In addition to straight line segment P_i+2P_i+3、P_i+3P_i+4Vector angle of (theta)_i+3And straight line segment P_i+3P_i+4、P_i+4P_i+5Vector angle of (theta)_i+4Greater than the maximum rotation angle theta set by the system_maxAll others are less than theta_max. At this time, the program segment P is inferred_iP_i+1、P_i+1P_i+2、P_i+2P_i+3Is a continuous micro-segment; program segment P_i+4P_i+5、P_i+5P_i+6Are continuous micro-segments.

Step 203 is executed: a starting point P₀And a disconnection point P adjacent thereto_nEnd point P_mAnd a disconnection point P adjacent thereto_n+1Or a continuous micro-segment portion between two adjacent disconnection points is identified as the continuous micro-segment portion P_i P_jWherein n and m are positiveAn integer, and n is more than i and less than or equal to m or n is more than j and less than or equal to m.

In a CNC program, in an irregular program segment generated by a CAM system, a part needing to be precisely machined often has the characteristic of a program segment with a large length or sharp angle change; the portion that can be continuously and smoothly compressed tends to have a short length and a gentle change in angle.

And identifying continuous micro-segments in the CNC program through the length of the line segments to be machined and the vector angle between the line segments. And judging whether the program segment in the CNC needs to be subjected to smooth compression processing or not through continuous micro-segment identification. The non-continuous micro-segment part is not subjected to smooth compression treatment; and (3) performing smooth compression treatment on the continuous micro-segment part: and processing the continuous micro-segment into a continuous smooth path, wherein the processed path and the original path meet a certain deviation range.

Specifically, according to practical experience, it is preferable that the preset micro-segment length threshold d is_maxIs 0 mm-2 mm. The preset angle threshold value is 0-30 degrees.

In particular, the continuous micro-segment portion P_i P_jThe step of smooth compression into a spline curve satisfying the machining accuracy includes:

step 310: obtaining and said continuous micro-segment portion P_i P_jAnd node vector parameters corresponding to the micro-segment command points.

The method for acquiring the node vector parameters comprises the following steps:

according to the chord length delta P between two adjacent micro-segment command points_iVector P formed by three adjacent micro-segment command points_i-1P_iP_i+1To obtain and micro-segment instruction point P_iCorresponding node vector parameter u_i。

Node vector parameter u_iCalculated according to the following formula:

wherein

Wherein u is_i(i ═ 1,2,. cndot., n) as parameter value, |.

DELTA.P

_i1,2, n-1 is two adjacent programming points (x)_i,y_i,z_i) And (x)_i+1,y_i+1,z_i+1) inter-Euclidean distance, angle P_i-1P_iP_i+1Is a vector P_i-1P_iAnd P_iP_i+1The vector angle formed.

Step 320 is executed: through said continuous micro-segment portion P_i P_jConstructing an interpolation curve by the upper continuous 4 micro-segment command points to calculate a first tangent vector corresponding to the 4 micro-segment command points, wherein the first tangent vector comprises the following steps:

according to successive micro-segment instruction points P_i-2、P_i-1、P_i、P_i+1、P_i+2And the node vector parameter value u corresponding to each instruction point_i-2、u_i-1、u_i、u_i+1、u_i+2Constructing 4 micro-segment instruction points P respectively passing through_i-2、P_i-1、P_iAnd P_i+1Of a cubic polynomial interpolation curve Q_i-2(u) and passing through 4 consecutive instruction points P of said micro-segment_i-1、P_i、P_i+1And P_i+2Of a cubic polynomial interpolation curve Q_i-1(u)；

Solving two cubic polynomial interpolation curves Q_i-2(u)、Q_i-1(u) at the micro-segment instruction point P_iFirst order tangent vector Q'_i-2(u_i)、Q'_i-1(u_i)；

The obtained micro-segment command point P_iFirst order tangent vector Q'_i-2(u)、Q'_i-1(u) average value as the micro-segment instruction point P_iCorresponding first order tangent vector value T_i。

The CNC machining program contains a large number of G01 instructions describing the shape of a workpiece to be machined, and the program does not contain a first tangent vector value of a programming point, and the first tangent vector of the programming point needs to be determined through the programming point and two points, namely a front point and a rear point. Specifically, in this embodiment, the specific process of solving the first order tangent vector is as follows:

programming point is P_iAnd two successive program points P successive thereto_i-2、P_i-1、P_i+1、P_i+2Corresponding node vector parameter is u_i-2、u_i-1、u_i、u_i+1、u_i+2Two cubic polynomial interpolation curves can be constructed to pass through 4 continuous programming points P respectively_i-2、P_i-1、P_iAnd P_i+1And P_i-1、P_i、P_i+1And P_i+2。

Q_i-2(u)＝a_i-2+b_i-2u+c_i-2u²+d_i-2u³,u∈[u_i-2,u_i+1]

Q_i-1(u)＝a_i-1+b_i-1u+c_i-1u²+d_i-1u³,u∈[u_i-1,u_i+2]

Two interpolation curves Q are obtained_i-2(u)、Q_i-1(u) at a programming point P_iFirst order tangent vector Q'_i-2(u_i)、Q'_i-1(u_i) (ii) a Specifically, the above two cubic polynomials correspond to the coefficient a through 4 successive programming points_i-2、b_i-2、c_i-2、d_i-2And a_i-1、b_i-1、c_i-1、d_i-1The following formula is satisfied:

will program the point P_i-2、P_i-1、P_i、P_i+1And P_i+2And corresponding node vector parameter value u_i-2、u_i-1、u_i、u_i+1And u_i+2Substituting the equation to obtain a cubic polynomial curve Q_i-2(u) and Q_i-1Coefficient a of (u)_i-2、b_i-2、c_i-2、d_i-2And a_i-1、b_i-1、c_i-1、d_i-1. Two cubic polynomial curves at the programming point P_iThe first order tangent vector of (A) is:

Q'_i-2(u_i)＝b_i-2+2c_i-2u_i+3d_i-2u_i ²

Q'_i-1(u_i)＝b_i-1+2c_i-1u_i+3d_i-1u_i ²

the obtained programming point P_iFirst order tangent vector Q'_i-2(u_i)、Q'_i-1(u_i) As the programming point P_iCorresponding first order tangent vector value T_i。

In order to make the calculated first-order tangent order approximate to the first-order tangent order of the program smooth compression acquisition curve, two cubic polynomials are taken at a programming point P_iThe average value of the first-order tangent vectors is taken as the first-order tangent vector of the programming pointIs T_iDetermined according to the following formula:

the first tangent vector of the two foremost and rearmost programming points of the successive micro-segments is determined by the following formula:

step 330: according to the continuous micro-segment part P_i P_jA micro-segment instruction point, a node vector parameter corresponding to the micro-segment instruction point, and a continuous micro-segment part P_i P_jA first tangent vector corresponding to the continuous 4 micro-segment command points on the surface of the substrate, and a continuous micro-segment part P_i P_jCompressed into a first order continuous smooth cubic Bezier curve, represented by P₁P₂，P₂P₃，…，P_n-1P_nComposed of successive micro-segments, target curves to be synthesized

Wherein C is_t(u) is a cubic Bezier curve.

The continuous micro-segment part P_i P_jThe step of compressing into the first order continuous smooth spline curve satisfying the machining accuracy includes: for program segment P₁P₂，P₂P₃，…，P_n-1P_nThe formed continuous micro-segment is compressed into a multi-segment cubic Bezier curve C meeting the processing precision_t(u) including control point calculation and machining error control, comprising:

step 331 is executed: calculating the starting point P of the continuous micro-segment part to be smoothly compressed_iAnd a termination point P_jControl point G of the curve in between₁And G₂。

The calculation micro-segment instruction point P_iAnd P_jThe method of curve control point in between comprises:

when the micro-segment instruction point P_iAnd P_jIs a non-adjacent micro-segment instruction point, and P_i、P_j、T_i、T_jWhen the planes are coplanar, calculating and sequentially approaching micro-segment instruction points P according to a least square method_kCurve control point G of_k1And G_k2Wherein the micro-segment instruction point P_kFor instruction point P of micro-segment_iAnd P_jMicro-segment instruction points in between.

For example, assume a micro-segment instruction point is P_iAnd P_jThe corresponding first order tangent vector is T_iAnd T_jCurve C_t(u) is the curve S (u) at the programming point P_iAnd P_jThe curve segment between, P_kK e (i j) is at the programming point P_iAnd P_jThe programming point in between.

The starting point P of the instruction point passing through the micro segment can be calculated according to the following steps_iEnd point P_jAnd an intermediate point P_kOf the cubic Beizer curve of_k1And G_k2：

Calculating the plane pi and the passing P_kAnd parallel to T_jPoint of intersection P of straight lines of_d；

② calculating straight line P_i P_jAnd through P_dAnd parallel to T_iPoint of intersection P of straight lines of_c；

Thirdly, calculating the control points G of the other 2 Beizer curves_k1And G_k2：

when the micro-segment instruction point P_iAnd P_jIs a non-adjacent micro-segment instruction point, and P_i、P_j、T_i、T_jWhen not coplanar, sequentially calculating instruction points P passing through micro-segment_kCurve control point G of_k1Coefficient parameter alpha and curve control point G_k2The coefficient parameter β of (a);

when alpha > 0 and beta < 0, a curve control point G is calculated from the coefficient parameters alpha and beta₁And G₂；

For example, the starting point P of the instruction point passing through the micro segment can be calculated according to the following steps_iEnd point P_jAnd an intermediate point P _k2 other control points of the cubic Beizer curve:

uniformization of chord length parameter u_i～u_jIs composed of

Solving the unknown numbers alpha and beta by using a least square method according to the following formula:

(3s²tT_i)α+(3t²sT_j)β＝P_k-(s³+3s²t)P_i-(t³+3t²s)P_j

s(s-2t)(T_k×T_i)α+t(2s-t)(T_k×T_j)β＝2st(T_k×(P_i-P_j))

wherein, T_kTo program point P_kThe corresponding first order tangent vector, s and t, is determined as follows:

checking whether alpha is more than 0 and beta is less than 0, if so, calculating:

G_k1＝P_i+αT_i

G_k2＝P_j+βT_j

when alpha is less than or equal to 0 or beta is greater than or equal to 0, making j reduce by 1, if j is>i +1, calculating a curve control point G according to the coefficient parameters alpha and beta₁And G₂(ii) a If j is i +1, the control point G is directly calculated₁And G₂.

The step of adjusting the curve control points according to the machining error comprises:

when the micro-segment instruction point P_iAnd P_jWhen the instruction points are non-adjacent micro-segment instruction points, calculating the obtained curve control point G_k1And G_k2Mean value G of₁And G₂；

Wherein k is_iA system number value corresponding to the starting point of the curve segment; k is a radical of_jAnd the system number value corresponding to the end point of the curve segment is obtained.

Calculate by P_i、G₁、G₂、P_jThe deviation delta E of the fitted cubic Bezier curve of the control points;

judging whether the deviation delta E is smaller than a preset deviation E or not;

the deviation can be determined, for example, according to the following formula:

wherein the content of the first and second substances,

is u_kThe corresponding programming point instruction value;

is u_kAt spline curve C_t(u) function value of (u).

When the deviation Delta E is smaller than the preset deviation E, the value is calculated by P_i、G₁、G₂、P_jFitting cubic Bezier curves for the control points to serve as the first-order continuous smooth spline curve meeting the machining precision;

when the deviation delta E is larger than or equal to the preset deviation E, j is made to be j-1, and then P is recalculated_iAnd P_jControl point G of the curve in between₁And G₂。

For example, the method of solving the control points may be as follows:

establishing a quadratic equation to be recorded as: alpha²+ B α + C ═ 0 where:

A＝16-|T_i+T_j|²

B＝12(P_j-P_i)·(T_i+T_j)

C＝-36|P_j-P_i|²

and solving parameter coefficients according to a root equation:

the control points can be found:

step 332: obtaining a curve control point G₁And G₂Correspondingly fitting a cubic Bezier curve;

step 333: adjusting the curve control point G according to the machining error₁And G₂And adjusting and fitting the cubic Bezier curve to obtain the first-order continuous smooth spline curve meeting the processing precision.

Step 400, the remaining micro-segment P is compressed smoothly in the same way_k P_jTo obtain the remaining micro-segment partP_kP_jAnd (5) processing curves of the sub-targets corresponding to the instruction points.

Specifically, the remaining micro-segment portion P is smoothly compressed in a manner that repeats step 300_k P_jTo obtain a remaining micro-segment portion P_k P_jAnd (5) processing curves of the sub-targets corresponding to the instruction points.

In particular, if the continuous micro-segment portion P_k P_jCan be smoothly compressed into a spline curve meeting the processing precision, i.e. form a continuous micro-segment part P_k P_jA corresponding target processing curve;

if a continuous micro-segment portion P_k P_jCan not be compressed smoothly into a spline curve meeting the processing precision, and j is reduced to f until a continuous micro-segment part P_k P_fCan be smoothly compressed into a spline curve meeting the processing precision, and then the continuous micro-segment part P is obtained_k P_fCorresponding sub-target processing curves;

the remaining micro-segment portion P is then compressed smoothly in the same manner_f P_jTo obtain a remaining micro-segment portion P_f P_jAnd (5) processing curves of the sub-targets corresponding to the instruction points.

Step 500, connecting all sub-target processing curves in sequence to obtain a continuous micro-segment part P_iP_jThe target processing curve of (1).

The continuous micro-segment part P_i P_jCompressing into a first-order continuous smooth spline when the instruction point P is a micro-segment_iAnd P_jWhen the instruction points are adjacent micro-segment instruction points, namely j ═ i +1, the curve control point G is directly calculated₁And G₂To obtain a fitting curve C_t(u) and fitting the curve C_t(u) as a continuous micro-segment P_i P_jThe corresponding target curve.

The method comprises the following steps:

In the step (I) of the method, the specific process of continuous micro-segment identification is as follows:

identifying successive micro-segment portions P_i P_j。

The continuous micro-segment part P_i P_jObtaining a target processing curve according to the deviation range:

if the continuous micro-segment portion P_i P_jCan be smoothly compressed into a spline curve meeting the processing precision, i.e. form a continuous micro-segment part P_i P_jCorresponding target processing curve.

In the step (II) of the method, the specific process of node vector parameterization is as follows:

will P₁P₂，P₂P₃，…，P_n-1P_nThe composition of continuous micro-segment is fit-synthesized by a plurality of segments of cubic Beizer curve C_t(u) a target curve S (u), C_t(u) is the target curve S (u) at the programming point P_iAnd P_jThe third Beizer curve in between. Need to be aligned to the programming point P_i(namely, the instruction points of the micro-segment) are parameterized, and each programming point P is obtained according to the length relation and the angle relation between the programming points_iCorresponding node vector parameter value u_iParameterization is performed according to the following formula:

as shown in FIG. 3, in the step (IV), the cubic Bezier curve C is obtained according to the deviation range_tThe specific process of (u) is as follows:

reading in continuous micro-segment P_i(i is more than or equal to 1 and less than or equal to n) and corresponding first-order tangent vector T_i(1≤i≤n)；

② i is 1, j is n;

(iii) judging whether j is i +1, i.e. judging P_i、P_jIf j > i +1, i.e. P_i、P_jNot adjacent programming points (i.e. non-adjacent micro-segment instruction points), the following steps are entered:

fourthly, judging P_i、P_j、T_i、T_jOr coplanar. If coplanar, calculating to approximate to P in sequence according to least square method_k(i < k < j) curve control point G_k1And G_k2(ii) a If not, the following steps are carried out:

calculating the approaching point P in turn_k(i < k < j) curve control point G_k1And G_k2If the coefficient parameters alpha and beta do not satisfy the conditions that alpha is greater than 0 and beta is less than 0, j is made to be j-1, and the process returns to the step (iv); otherwise, the following steps are carried out:

calculating control point G_k1And G_k2Mean value G of₁And G₂If the deviation requirement E is satisfied, P_i、P_jThe straight line segment between is represented by P_i、G₁、G₂And P_jCubic Beizer curve substitution for 4 control points; let i be j, j be n, returnReturning to the step IV; otherwise, let j equal to j-1, return to step c.

The specific process of the control point calculation in the step (IV) of the invention is as follows:

1. if j is i +1, a spline curve is directly simulated, and the method for solving the control points is as follows:

A＝16-|T_i+T_j|²

B＝12(P_j-P_i)·(T_i+T_j)

C＝-36|P_j-P_i|²

and solving parameter coefficients according to a root equation:

the control points can be found:

2. if j > i + 1:

assume a programming point of P_iAnd P_jThe corresponding first order tangent vector is T_iAnd T_jCurve C_t(u) is the curve S (u) at the programming point P_iAnd P_jThe curve segment between, P_kK e (i j) is at the programming point P_iAnd P_jThe programming point in between.

Calculating a starting point P passing or approaching the programmed point_iEnd point P_jAnd a middle programming point P_kThe specific course of the other 2 control points of the cubic Beizer curve for k e (i j) is as follows:

1)T_jin the process of P_i、P_j、T_iWithin a defined plane pi

As shown in fig. 4A, the solving process is as follows:

a) calculating the pi and P of the plane_kAnd parallel to T_jPoint of intersection P of straight lines of_d；

b) Calculating straight line P_i P_jAnd through P_dAnd parallel to T_iPoint of intersection P of straight lines of_c；

c) Calculate the control points G of the other 2 Beizer curves_k1And G_k2：

2)T_jIs not at P_i、P_j、T_iWithin a defined plane pi

As shown in fig. 4B, the solving process is as follows:

a) uniform chord length parameter u_i～u_jIs composed of

b) Solving the unknowns α and β with a least squares method according to:

(3s²tT_i)α+(3t²sT_j)β＝P_k-(s³+3s²t)P_i-(t³+3t²s)P_j

s(s-2t)(T_k×T_i)α+t(2s-t)(T_k×T_j)β＝2st(T_k×(P_i-P_j))

c) checking whether alpha is greater than 0 and beta is less than 0, if yes, calculating

G_k1＝P_i+αT_i

G_k2＝P_j+βT_j

If not, let j subtract 1, return to step c to recalculate the curve control point.

In the step (four), if j is larger than i +1, whether the machining error meets the requirement needs to be further judged. The specific process of machining error calculation is as follows:

according to the obtained control point G_k1And G_k2The average value is obtained according to the following formula

Candidate cubic Bezier curve C_t(u) by control point by P_i、G₁、G₂And P_jAs defined. The deviation calculation of the fitted curve is determined according to the following formula:

wherein the content of the first and second substances,

is u_kThe corresponding system instruction value;

is uk at spline C_tAnd (u) the corresponding spline curve.

If the deviation is within the preset range E, the control point P is used_i、G₁、G₂And P_jDefined cubic Bezier curve C_t(u) instead of P_i、P_jA straight line segment in between; if the requirement is not met, the step c is returned to for recalculating the curve control point by changing j to j-1.

In the step (IV) of the invention, the smooth compression program section in the precision requirement range is as follows: according to the instruction value P corresponding to the programming point of the continuous micro-segment_iNode vector parameter value u_iAnd a first order tangent vector value T_iA 1 is to P₁P₂，P₂P₃，…，P_n-1P_nThe composition of continuous micro-segment is fit-synthesized by a plurality of segments of cubic Beizer curve C_t(u) a target curve S (u), C_t(u) is the target curve S (u) at the programming point P_iAnd P_jA cubic Beizer curve in between, wherein point P is to be programmed_iAnd P_jThe continuous micro-segment between the two is compressed into a curve C_t(u) comprises the steps of:

step (four-one) of calculating a programming point P_iAnd P_jControl point G of the curve in between₁And G₂To obtain a fitted curve;

step (four two) according to curve control point G₁And G₂And performing machining error control to adjust the fitting curve.

Wherein, in the step (IV), the program point P is calculated_iAnd P_jThe control points of the curve in between to obtain the fitting curve comprises the following steps:

step (four one for one) of judging a programming point P_iAnd P_jWhether it is a non-adjacent programming point;

step (four or two) if programming point P_iAnd P_jFor non-adjacent programming points, the programming point P is noted_kTo program point P_iAnd P_jThe programming point between, judge P_i、P_j、T_i、T_jIf coplanar, calculating approximate programming point P according to least square method_kCurve control point G of_k1And G_k2。

For example, assume a program point of P_iAnd P_jThe corresponding first order tangent vector is T_iAnd T_jCurve C_t(u) is the curve S (u) at the programming point P_iAnd P_jThe curve segment between, P_kK e (i j) is at the programming point P_iAnd P_jThe programming point in between.

The starting point P for the programmed point can be calculated as follows_iEnd point P_jAnd an intermediate programming point P_kOf the cubic Beizer curve of_k1And G_k2：

Wherein, in step (four or two), if P_i、P_j、T_i、T_jIf not, calculating approximate programming point P_kCurve control point G of, k e (i j)_k1And G_k2The coefficient parameters α and β.

For example, the starting point P for the programmed point can be calculated as follows_iEnd point P_jAnd an intermediate programming point P _k2 other control points of the cubic Beizer curve:

uniformization of chord length parameter u_i～u_jIs composed of

(3s²tT_i)α+(3t²sT_j)β＝P_k-(s³+3s²t)P_i-(t³+3t²s)P_j

s(s-2t)(T_k×T_i)α+t(2s-t)(T_k×T_j)β＝2st(T_k×(P_i-P_j))

G_k1＝P_i+αT_i

G_k2＝P_j+βT_j

if not, let j subtract 1 and go back to step (four one) to recalculate the curve control point.

Wherein, in the step (IV), the control of the machining error according to the curve control point is carried out at a programming point P_iAnd P_jThe method is carried out under the condition of non-adjacent programming points and comprises the following steps:

step (four two one) of calculating the obtained curve control point G_k1And G_k2Mean value G of₁And G₂；

Step (four two) calculation with P_i、G₁、G₂、P_jFitting a curve C to the control points_i(u) a deviation Δ E;

step (four, two and three) of judging whether the deviation delta E is smaller than the preset deviation E, if so, the deviation delta E is determined to be P_i、G₁、G₂、P_jFitting a curve C to the control points_i(u) as a programming point P_iAnd P_jTarget curve in between.

Wherein, in the step (four two one), the average value G₁And G₂For example, it can be obtained according to the following formula:

In step (four, two), the deviation can be determined according to the following formula:

wherein the content of the first and second substances,

is u_kThe corresponding programming point instruction value;

is u_kAt spline curve C_t(u) function value of (u).

In the step (forty-two-three), if the result of determining whether the deviation Δ E is smaller than the preset deviation E is no, j is made to be j-1, and the process returns to the step (forty-one) to recalculate the curve control point.

Wherein, in step (four one for one)) In, if the point P is programmed_iAnd P_jFor adjacent programming points, the curve control points are directly calculated to obtain a fitting curve C_t(u) and fitting the curve C_t(u) as a programming point P_iAnd P_jTarget curve in between.

For example, the method of solving the control points may be as follows:

A＝16-|T_i+T_j|²

B＝12(P_j-P_i)·(T_i+T_j)

C＝-36|P_j-P_i|²

and solving parameter coefficients according to a root equation:

the control points can be found:

fig. 5 shows the simulation effect of the method of the invention, as shown in fig. 5, the path curve obtained according to the method of the invention is smoother compared to the original machining path.

In order to further verify the effect of the method of the present invention in actual numerical control machining, the method of the present invention was applied to program segment processing in numerical control machining, and the results of machining using the method of the present invention and the results of machining not using the method of the present invention are shown in fig. 6A and 6B.

As can be seen from a comparison of fig. 6A and 6B, the machined surface obtained by using the method of the present invention has almost no asperities and is significantly smoother.

The method of the invention has the following beneficial effects and advantages:

1. high efficiency: the algorithm is integrated in the machine tool, so that the time consumed by CAM software for providing smaller tolerance data is avoided, and the generation efficiency of the whole part is improved;

2. the accuracy is as follows: the algorithm can restore the design prototype of the workpiece in the CAM software on line according to the point information provided by the CAM software;

3. stability: the algorithm of the invention fits a large number of micro-segments into a curve, effectively reduces the vibration of the machine tool through curve interpolation, and improves the stability of the machine tool.

While this invention has been described in terms of a preferred embodiment, there are alterations, permutations, and various substitute equivalents, which fall within the scope of this invention. It should also be noted that there are many alternative ways of implementing the methods and systems of the present invention. It is therefore intended that the following appended claims be interpreted as including all such alterations, permutations, and various substitute equivalents as fall within the true spirit and scope of the present invention.

As shown in fig. 7, in an embodiment, the numerical control machining system of communication signals of the present invention includes a machining program curve providing module 71, a continuous micro-segment identifying module 72, and a target machining curve module 73.

The machining program curve providing module 71 is adapted to provide a machining program curve P required by the numerical control machining apparatus₀P_nSaid machining program curve P₀P_nComprises at least two micro-segment instruction points P_i。

The continuous micro-segment recognition module 72 is adapted to recognize the continuous micro-segment part P_iP_j。

The target processing curve module 73 comprises a smoothing and compression unit adapted to compress the continuous micro-segment portion P_iP_jObtaining a target processing curve according to the deviation range: if the continuous micro-segment portion P_iP_jCan be smoothly compressed into a spline curve meeting the processing precision, i.e. form a continuous micro-segment part P_iP_jA corresponding target processing curve; smooth compressionUnit adapted to be in a continuous micro-segment part P_iP_jWhen the sample curve which can not be smoothly compressed and meets the processing precision is obtained, j is reduced to k until the continuous micro-segment part P_iP_kCan be smoothly compressed into a spline curve meeting the processing precision, and then the continuous micro-segment part P is obtained_iP_kCorresponding sub-target processing curves; the smoothing compression unit is further adapted to smooth-compress the remaining micro-segment portion P again in the same manner_kP_jTo obtain a remaining micro-segment portion P_k P_jAnd (5) processing curves of the sub-targets corresponding to the instruction points.

The target processing curve module 73 is further adapted to sequentially connect all sub-target curves to obtain a continuous micro-segment portion P_iP_jThe target processing curve of (1).

Wherein, P_iFor the machining program curve P₀P_nAnd k is more than or equal to i and j is more than or equal to m at any micro-segment instruction point, and the j is a positive integer.

Specifically, the numerical control machining equipment machines the workpiece according to the target machining curve.

The continuous micro-segment recognition module 72 includes: a length comparison unit adapted to compare the machining program curve P₀P_mUpper adjacent two micro-segment instruction point P_n，P_n+1Length between and a preset micro-segment length threshold d_maxComparing, if the length between the two adjacent instruction points is greater than the threshold d of the micro-segment length_maxThen the corresponding two micro-segment instruction points P are set_n，P_n-1Set as the break-off point of the continuous micro-segment;

an angle comparison unit suitable for comparing the adjacent three micro-segment command points P_n-1，P_n，P_n+1Formed vector angle P_n-1P_nP_n+1Comparing the vector angle with a preset angle threshold value, and if the vector angle is larger than the angle threshold value, determining a micro-segment instruction point P corresponding to the intersection point of the vector angle_nSet as the break-off point of the continuous micro-segment;

an identification unit adapted to identify as said start/end point and an adjacent breakpoint or a continuous micro-segment portion between two adjacent breakpoint pointsContinuous micro-segment part P_iP_jStarting point P₀And a disconnection point P adjacent thereto_nEnd point P_mAnd a disconnection point P adjacent thereto_n+1Or a continuous micro-segment portion between two adjacent disconnection points is identified as the continuous micro-segment portion P_i P_jWherein n and m are positive integers, and n is more than i and less than or equal to m or n is more than j and less than or equal to m.

Specifically, the smooth compression unit includes: a node vector parameter component adapted to obtain a vector of parameters associated with said continuous micro-segment portion P_i P_jNode vector parameters corresponding to the micro-segment instruction points on the micro-segment instruction points; a first order sagittal assembly adapted to pass through said continuous micro-segment portion P_i P_jConstructing an interpolation curve by the upper continuous 4 micro-segment command points to calculate a first tangent vector corresponding to the 4 micro-segment command points; a spline curve generation component for generating a spline curve from the continuous micro-segment portion P_i P_jA micro-segment instruction point, a node vector parameter corresponding to the micro-segment instruction point, and a continuous micro-segment part P_i P_jA first tangent vector corresponding to the continuous 4 micro-segment command points on the surface of the substrate, and a continuous micro-segment part P_i P_jCompressed into a first order continuous smooth spline curve.

In particular, the node vector parameter component is suitable for being used for adjusting the chord length delta P between two adjacent micro-segment instruction points_iVector angle P formed by the instruction points of three adjacent micro-segments_i-1P_iP_i+1To obtain and micro-segment instruction point P_iCorresponding node vector parameter u_i。

Specifically, the first order tangent vector assembly includes: a binomial interpolation curve part suitable for the instruction point P of continuous micro-segment_i-2、P_i-1、P_i、P_i+1、P_i+2And the node vector parameter value u corresponding to each instruction point_i-2、u_i-1、u_i、u_i+1、u_i+2Constructing 4 micro-segment instruction points P respectively passing through_i-2、P_i-1、P_iAnd P_i+1Of a cubic polynomial interpolation curve Q_i-2(u) and passing through 4 consecutive instruction points P of said micro-segment_i-1、P_i、P_i+1And P_i+2Of a cubic polynomial interpolation curve Q_i-1(u); a one-order vector cutting component of the micro-segment instruction point, which is suitable for solving the two cubic polynomial interpolation curves Q_i-2(u)、Q_i-1(u) at the micro-segment instruction point P_iFirst order tangent vector Q'_i-2(u_i)、Q'_i-1(u_i) (ii) a A first tangent vector averaging part adapted to average the obtained micro-segment command point P_iFirst order tangent vector Q'_i-2(u)、Q'_i-1(u) average value as the micro-segment instruction point P_iCorresponding first order tangent vector value T_i。

Specifically, the spline curve generation component includes: a control point calculation unit adapted to calculate a starting point P of a continuous micro-segment portion to be smoothly compressed_iAnd a termination point P_jControl point G of the curve in between₁And G₂(ii) a A Bezier curve acquisition unit adapted to acquire and curve control points G₁And G₂Correspondingly fitting a cubic Bezier curve; a machining error control part adapted to let the control point calculation unit adjust the curve control point G according to a machining error₁And G₂And adjusting and fitting the cubic Bezier curve to obtain the first-order continuous smooth spline curve meeting the processing precision.

The control point calculation unit includes: a first calculation unit adapted to calculate a micro-segment command point P_iAnd P_jIs a non-adjacent micro-segment instruction point, and P_i、P_j、T_i、T_jWhen the planes are coplanar, calculating and sequentially approaching micro-segment instruction points P according to a least square method_kCurve control point G of_k1And G_k2Wherein the micro-segment instruction point P_kFor instruction point P of micro-segment_iAnd P_jMicro-segment instruction points in between.

The curve control point calculation unit includes: a control point coefficient calculating unit adapted to calculate a control point coefficient when the micro-segment command point P is detected_iAnd P_jIs a non-adjacent micro-segment instruction point, and P_i、P_j、T_i、T_jWhen not coplanar, sequentially calculating instruction points P passing through micro-segment_kCurve control point G of_k1Coefficient parameter alpha and curve control point G_k2The coefficient parameter β of (a); a second calculation unit adapted to calculate a curve control point G based on the coefficient parameters alpha and beta when alpha > 0 and beta < 0₁And G₂(ii) a A third calculation unit adapted to, when alpha ≦ 0 or beta ≧ 0, the compression unit adapted to self-subtract j by 1, then j by 1, if j is>i +1, calculating a curve control point G according to the coefficient parameters alpha and beta₁And G₂(ii) a If j is i +1, the control point G is directly calculated₁And G₂。

The machining error control means includes: a control point mean value calculation unit suitable for calculating the mean value of the micro-segment instruction point P_iAnd P_jWhen the instruction points are non-adjacent micro-segment instruction points, calculating the obtained curve control point G_k1And G_k2Mean value G of₁And G₂(ii) a A deviation calculation unit adapted to calculate P_i、G₁、G₂、P_jThe deviation delta E of the fitted cubic Bezier curve of the control points; an adjusting unit adapted to adjust the deviation Delta E by P when the deviation Delta E is smaller than a preset deviation E_i、G₁、G₂、P_jFitting cubic Bezier curves for the control points to serve as the first-order continuous smooth spline curve meeting the machining precision; when the deviation delta E is larger than or equal to the preset deviation E, a fourth curve control point calculating component is adopted, the fourth curve control point calculating component is suitable for enabling j to be j-1, and then P is recalculated_iAnd P_jControl point G of the curve in between₁And G₂。

The smooth compression unit further includes a fifth curve control point calculation section adapted to calculate a fifth curve control point at the micro-segment command point P_iAnd P_jWhen the instruction points are adjacent micro-segment instruction points, namely j ═ i +1, curve control points are directly calculated to obtain a fitting curve C_t(u) and fitting the curve C_t(u) as a continuous micro-segment P_i P_jThe corresponding target curve.

It should be noted that the structures and principles of the processing program curve providing module 71, the continuous micro-segment identifying module 72 and the target processing curve module 73 correspond to the steps in the numerical control processing method of the communication signal one by one, and therefore, the description thereof is omitted.

It should be noted that the division of the modules of the above system is only a logical division, and the actual implementation may be wholly or partially integrated into one physical entity, or may be physically separated. And these modules can be realized in the form of software called by processing element; or may be implemented entirely in hardware; and part of the modules can be realized in the form of calling software by the processing element, and part of the modules can be realized in the form of hardware. For example, the x module may be a processing element that is set up separately, or may be implemented by being integrated in a chip of the apparatus, or may be stored in a memory of the apparatus in the form of program code, and the function of the x module may be called and executed by a processing element of the apparatus. Other modules are implemented similarly. In addition, all or part of the modules can be integrated together or can be independently realized. The processing element described herein may be an integrated circuit having signal processing capabilities. In implementation, each step of the above method or each module above may be implemented by an integrated logic circuit of hardware in a processor element or an instruction in the form of software.

For example, the above modules may be one or more integrated circuits configured to implement the above methods, such as: one or more Specific Integrated circuits (ASICs), or one or more Microprocessors (MPUs), or one or more Field Programmable Gate Arrays (FPGAs), etc. For another example, when one of the above modules is implemented in the form of a Processing element scheduler code, the Processing element may be a general-purpose processor, such as a Central Processing Unit (CPU) or other processor capable of calling program code. For another example, these modules may be integrated together and implemented in the form of a system-on-a-chip (SOC).

In an embodiment of the present invention, the present invention further includes a computer-readable storage medium, on which a computer program is stored, and the computer program, when executed by a processor, implements any of the above numerical control processing methods for communication signals.

Those of ordinary skill in the art will understand that: all or part of the steps for implementing the above method embodiments may be performed by hardware associated with a computer program. The aforementioned computer program may be stored in a computer readable storage medium. When executed, the program performs steps comprising the method embodiments described above; and the aforementioned storage medium includes: various media that can store program codes, such as ROM, RAM, magnetic or optical disks.

In summary, the numerical control machining method and the numerical control machining equipment of the invention are used for providing the micro-segment smooth compression processing method for numerical control machining, which can meet the production requirements in terms of both precision and efficiency. Therefore, the invention effectively overcomes various defects in the prior art and has high industrial utilization value.

The foregoing embodiments are merely illustrative of the principles and utilities of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or change the above-mentioned embodiments without departing from the spirit and scope of the present invention. Accordingly, it is intended that all equivalent modifications or changes which can be made by those skilled in the art without departing from the spirit and technical spirit of the present invention be covered by the claims of the present invention.

Claims

1. A numerical control machining method is characterized by comprising the following steps:

providing a machining program curve P required by numerical control machining equipment₀ P_nSaid machining program curve P₀ P_nComprises at least two micro-segment instruction points P_iAnd P_j；

Identifying successive micro-segment portions P_i P_j；

if the continuous micro-segment portion P_i P_jCan be smoothly compressed into spline curves meeting the processing precision, i.e. form continuous micro-segmentsPart P_i P_jA corresponding target processing curve;

if a continuous micro-segment portion P_i P_jCan not be smoothly compressed into a spline curve meeting the processing precision, and j is reduced to k until a continuous micro-segment part P_i P_kCan be smoothly compressed into a spline curve meeting the processing precision, and then the continuous micro-segment part P is obtained_i P_kCorresponding sub-target processing curves;

the remaining micro-segment portion P is then compressed smoothly in the same manner_k P_jTo obtain a remaining micro-segment portion P_k P_jProcessing curves of the sub-targets corresponding to the instruction points;

all the sub-target processing curves are connected in sequence to obtain a continuous micro-segment part P_i P_jThe target machining curve of (1);

wherein, P_iFor the machining program curve P₀ P_nAnd k is more than or equal to i and j is more than or equal to m at any micro-segment instruction point, and the j is a positive integer.

2. The numerical control machining method according to claim 1, characterized in that the continuous micro-segment portion P is obtained_i P_jAfter the target machining curve is obtained, the numerical control machining equipment machines the workpiece according to the target machining curve.

3. The numerical control machining method according to claim 1, characterized in that the identification of the continuous micro-segment portion P is carried out_i P_jThe method comprises the following steps:

curve P of the machining program₀ P_mUpper adjacent two micro-segment instruction point P_n，P_n+1Length between and a preset micro-segment length threshold d_maxComparing, if the length between the two adjacent instruction points is greater than the threshold d of the micro-segment length_maxThen the corresponding two micro-segment instruction points P are set_n，P_n-1Set as the break-off point of the continuous micro-segment;

three adjacent micro-segment instruction points P_n-1，P_n，P_n+1Formed vector angle P_n-1P_nP_n+1Comparing the vector angle with a preset angle threshold value, and if the vector angle is larger than the angle threshold value, enabling a programming point P corresponding to the intersection point of the vector angle_nSet as the break-off point of the continuous micro-segment;

a starting point P₀And a disconnection point P adjacent thereto_nEnd point P_mAnd a disconnection point P adjacent thereto_n+1Or a continuous micro-segment portion between two adjacent disconnection points is identified as the continuous micro-segment portion P_i P_jWherein n and m are positive integers, and n is more than i and less than or equal to m or n is more than j and less than or equal to m.

4. The numerical control machining method according to claim 1, characterized in that the continuous micro-segment portion P is divided into_i P_jThe step of smooth compression into a spline curve satisfying the machining accuracy includes:

obtaining and said continuous micro-segment portion P_i P_jNode vector parameters corresponding to the micro-segment instruction points on the micro-segment instruction points;

through said continuous micro-segment portion P_i P_jConstructing an interpolation curve by the upper continuous 4 micro-segment command points to calculate a first tangent vector corresponding to the 4 micro-segment command points;

according to the continuous micro-segment part P_i P_jA micro-segment instruction point, a node vector parameter corresponding to the micro-segment instruction point, and a continuous micro-segment part P_i P_jA first tangent vector corresponding to the continuous 4 micro-segment command points on the surface of the substrate, and a continuous micro-segment part P_i P_jCompressed into a first order continuous smooth spline curve.

5. The numerical control machining method according to claim 4, wherein the method of acquiring the node vector parameters includes:

according to the chord length delta P between two adjacent micro-segment command points_iVector angle P formed by the instruction points of three adjacent micro-segments_i- ₁P_iP_i+1To obtain and micro-segment instruction point P_iCorresponding node vector parameter u_i。

6. The numerical control machining method according to claim 4, characterized in that the continuous micro-segment portion P is passed through_i P_jThe step of constructing an interpolation curve for the upper continuous 4 micro-segment command points to calculate a first tangent vector corresponding to the 4 micro-segment command points includes:

7. The numerical control machining method according to claim 4, characterized in that the continuous micro-segment portion P is formed by cutting a continuous micro-segment_i P_jThe step of compressing into the first order continuous smooth spline curve satisfying the machining accuracy includes:

calculating the starting point P of the continuous micro-segment part to be smoothly compressed_iAnd a termination point P_jControl point G of the curve in between₁And G₂；

Obtaining a curve control point G₁And G₂Correspondingly fitting a cubic Bezier curve;

according to the processing errorSetting the curve control point G₁And G₂And adjusting and fitting the cubic Bezier curve to obtain the first-order continuous smooth spline curve meeting the processing precision.

8. The numerical control machining method according to claim 7, characterized in that the calculation micro-segment command point P_iAnd P_jThe method of curve control point in between comprises:

9. The numerical control machining method according to claim 7, characterized in that the calculation micro-segment command point P_iAnd P_jThe method of curve control point in between comprises:

When alpha is less than or equal to 0 or beta is greater than or equal to 0, making j reduce by 1, if j is>i +1, calculating a curve control point G according to the coefficient parameters alpha and beta₁And G₂(ii) a If j is i +1, the control point G is directly calculated₁And G₂。

10. The numerical control machining method according to claim 7, wherein the step of adjusting the curve control points according to the machining error includes:

judging whether the deviation Delta E is smaller than a preset deviation E or not,

11. The numerical control machining method according to claim 1, characterized in that the continuous micro-segment portion P is formed by cutting a continuous micro-segment_i P_jCompressing into a first-order continuous smooth spline when the instruction point P is a micro-segment_iAnd P_jWhen the instruction points are adjacent micro-segment instruction points, namely j ═ i +1, the curve control point G is directly calculated₁And G₂To obtain a fitting curve C_t(u) and fitting the curve C_t(u) as a continuous micro-segment P_i P_jThe corresponding target curve.

12. A numerical control machining apparatus, comprising:

a processing program curve providing module suitable for providing a processing program curve P required by the numerical control processing equipment₀ P_nSaid machining program curve P₀ P_nComprises at least two micro-segment instruction points P_i；

A continuous micro-segment recognition module adapted to recognize a continuous micro-segment part P_i P_j；

Target processing curve module including flatA sliding compression unit adapted to compress the continuous micro-segment portion P_iP_jObtaining a target processing curve according to the deviation range: if the continuous micro-segment portion P_i P_jCan be smoothly compressed into a spline curve meeting the processing precision, i.e. form a continuous micro-segment part P_i P_jA corresponding target processing curve;

a smooth compression unit adapted to compress the continuous micro-segment portion P_i P_jWhen the sample curve which can not be smoothly compressed and meets the processing precision is obtained, j is reduced to k until the continuous micro-segment part P_i P_kCan be smoothly compressed into a spline curve meeting the processing precision, and then the continuous micro-segment part P is obtained_i P_kCorresponding sub-target processing curves;

the smoothing compression unit is further adapted to smooth-compress the remaining micro-segment portion P again in the same manner_k P_jTo obtain a remaining micro-segment portion P_k P_jProcessing curves of the sub-targets corresponding to the instruction points;

the target processing curve module is also suitable for connecting all sub-target curves in sequence to obtain a continuous micro-segment part P_i P_jThe target machining curve of (1);

13. The numerical control machining apparatus according to claim 12, wherein the numerical control machining apparatus machines the workpiece in accordance with the target machining curve.

14. The numerical control machining apparatus according to claim 12, wherein the continuous micro-segment recognition module includes:

a length comparison unit adapted to compare the machining program curve P₀ P_mUpper adjacent two micro-segment instruction point P_n，P_n+1Length between and a preset micro-segment length threshold d_maxComparing, if the length between the instruction points of the two adjacent micro-segments is larger than the micro-segmentLength threshold d_maxThen the corresponding two micro-segment instruction points P are set_n，P_n-1Set as the break-off point of the continuous micro-segment;

an identification unit adapted to identify a start/end point and an adjacent break point or a continuous micro-segment portion between two adjacent break points as the continuous micro-segment portion P_i P_jStarting point P₀And a disconnection point P adjacent thereto_nEnd point P_mAnd a disconnection point P adjacent thereto_n+1Or a continuous micro-segment portion between two adjacent disconnection points is identified as the continuous micro-segment portion P_i P_jWherein n and m are positive integers, and n is more than i and less than or equal to m or n is more than j and less than or equal to m.

15. The numerical control machining apparatus according to claim 12, wherein the smooth compression unit includes:

a node vector parameter component adapted to obtain a vector of parameters associated with said continuous micro-segment portion P_i P_jNode vector parameters corresponding to the micro-segment instruction points on the micro-segment instruction points;

a first order sagittal assembly adapted to pass through said continuous micro-segment portion P_i P_jConstructing an interpolation curve by the upper continuous 4 micro-segment command points to calculate a first tangent vector corresponding to the 4 micro-segment command points;

a spline curve generation component for generating a spline curve from the continuous micro-segment portion P_i P_jA micro-segment instruction point, a node vector parameter corresponding to the micro-segment instruction point, and a continuous micro-segment part P_i P_jA first tangent vector corresponding to the continuous 4 micro-segment command points on the surface of the substrate, and a continuous micro-segment part P_i P_jCompressed into a first order continuous smooth spline curve.

16. The numerical control machining apparatus according to claim 15, wherein the nodal vector parameter assembly is adapted to be dependent on a chord length Δ P between two adjacent instruction points of the micro-segment_iVector angle P formed by the instruction points of three adjacent micro-segments_i-1P_iP_i+1To obtain and micro-segment instruction point P_iCorresponding node vector parameter u_i。

17. The digitally controlled machining device of claim 15, wherein the first tangent assembly includes:

a binomial interpolation curve part suitable for the instruction point P of continuous micro-segment_i-2、P_i-1、P_i、P_i+1、P_i+2And the node vector parameter value u corresponding to each instruction point_i-2、u_i-1、u_i、u_i+1、u_i+2Constructing 4 micro-segment instruction points P respectively passing through_i-2、P_i-1、P_iAnd P_i+1Of a cubic polynomial interpolation curve Q_i-2(u) and passing through 4 consecutive instruction points P of said micro-segment_i-1、P_i、P_i+1And P_i+2Of a cubic polynomial interpolation curve Q_i-1(u)；

A one-order vector cutting component of the micro-segment instruction point, which is suitable for solving the two cubic polynomial interpolation curves Q_i-2(u)、Q_i-1(u) at the micro-segment instruction point P_iFirst order tangent vector Q'_i-2(u_i)、Q'_i-1(u_i)；

A first tangent vector averaging part adapted to average the obtained micro-segment command point P_iFirst order tangent vector Q'_i-2(u)、Q'_i-1(u) average value as the micro-segment instruction point P_iCorresponding first order tangent vector value T_i。

18. The numerically controlled machining apparatus according to claim 15, wherein the spline curve generating assembly includes:

control point calculating unit, and control point calculating methodFor calculating the starting point P of the continuous micro-segment portion to be smoothly compressed_iAnd a termination point P_jControl point G of the curve in between₁And G₂；

A Bezier curve acquisition unit adapted to acquire and curve control points G₁And G₂Correspondingly fitting a cubic Bezier curve;

a machining error control part adapted to let the control point calculation unit adjust the curve control point G according to a machining error₁And G₂And adjusting and fitting the cubic Bezier curve to obtain the first-order continuous smooth spline curve meeting the processing precision.

19. The numerical control machining apparatus according to claim 18, characterized in that the control point calculation unit includes:

a first calculation unit adapted to calculate a micro-segment command point P_iAnd P_jIs a non-adjacent micro-segment instruction point, and P_i、P_j、T_i、T_jWhen the planes are coplanar, calculating and sequentially approaching micro-segment instruction points P according to a least square method_kCurve control point G of_k1And G_k2Wherein the micro-segment instruction point P_kFor instruction point P of micro-segment_iAnd P_jMicro-segment instruction points in between.

20. The numerical control machining apparatus according to claim 18, characterized in that the curve control point calculation unit includes:

a control point coefficient calculating unit adapted to calculate a control point coefficient when the micro-segment command point P is detected_iAnd P_jIs a non-adjacent micro-segment instruction point, and P_i、P_j、T_i、T_jWhen not coplanar, sequentially calculating instruction points P passing through micro-segment_kCurve control point G of_k1Coefficient parameter alpha and curve control point G_k2The coefficient parameter β of (a);

a second calculation unit adapted to calculate a curve control point G based on the coefficient parameters alpha and beta when alpha > 0 and beta < 0₁And G₂；

A third calculating means adapted to calculate when alpha is less than or equal to 0 or beta is more than or equal toAt 0, the compression unit is adapted to self-subtract j by 1, and then self-subtract j by 1 if j is>i +1, calculating a curve control point G according to the coefficient parameters alpha and beta₁And G₂(ii) a If j is i +1, the control point G is directly calculated₁And G₂。

21. The numerical control machining apparatus according to any one of claims 18, wherein the machining error control means includes:

a control point mean value calculation unit suitable for calculating the mean value of the micro-segment instruction point P_iAnd P_jWhen the instruction points are non-adjacent micro-segment instruction points, calculating the obtained curve control point G_k1And G_k2Mean value G of₁And G₂；

A deviation calculation unit adapted to calculate P_i、G₁、G₂、P_jThe deviation delta E of the fitted cubic Bezier curve of the control points;

an adjusting unit adapted to adjust the deviation Delta E by P when the deviation Delta E is smaller than a preset deviation E_i、G₁、G₂、P_jFitting cubic Bezier curves for the control points to serve as the first-order continuous smooth spline curve meeting the machining precision;

when the deviation delta E is larger than or equal to the preset deviation E, a fourth curve control point calculating component is adopted, the fourth curve control point calculating component is suitable for enabling j to be j-1, and then P is recalculated_iAnd P_jControl point G of the curve in between₁And G₂。

22. The numerical control machining apparatus according to claim 12, characterized in that the smooth compression unit further includes a fifth curve control point calculation section adapted to calculate a micro-segment command point P at the micro-segment command point P_iAnd P_jWhen the instruction points are adjacent micro-segment instruction points, namely j ═ i +1, curve control points are directly calculated to obtain a fitting curve C_t(u) and fitting the curve C_t(u) as a continuous micro-segment P_i P_jThe corresponding target curve.