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CN109597355A - The design method of the micro- texture numerical control processing generating tool axis vector of curved surface - Google Patents

The design method of the micro- texture numerical control processing generating tool axis vector of curved surface Download PDF

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CN109597355A
CN109597355A CN201811298656.0A CN201811298656A CN109597355A CN 109597355 A CN109597355 A CN 109597355A CN 201811298656 A CN201811298656 A CN 201811298656A CN 109597355 A CN109597355 A CN 109597355A
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tool
vector
microtexture
axis
tool axis
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CN109597355B (en
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张臣
魏盼
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Nanjing University of Aeronautics and Astronautics
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Nanjing University of Aeronautics and Astronautics
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    • G—PHYSICS
    • G05—CONTROLLING; REGULATING
    • G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
    • G05B19/00—Programme-control systems
    • G05B19/02—Programme-control systems electric
    • G05B19/18—Numerical control [NC], i.e. automatically operating machines, in particular machine tools, e.g. in a manufacturing environment, so as to execute positioning, movement or co-ordinated operations by means of programme data in numerical form
    • G05B19/404—Numerical control [NC], i.e. automatically operating machines, in particular machine tools, e.g. in a manufacturing environment, so as to execute positioning, movement or co-ordinated operations by means of programme data in numerical form characterised by control arrangements for compensation, e.g. for backlash, overshoot, tool offset, tool wear, temperature, machine construction errors, load, inertia

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Automation & Control Theory (AREA)
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Abstract

本发明提供了曲面微织构数控加工刀轴矢量的设计方法，包括以下步骤：1)将微织构模型引导线或微织构表面一定距离的偏置面的交线作为刀具路径曲线；2)根据刀具路径曲线、加工方向以及原光滑叶片曲面信息，在刀心点处建立三维坐标系；3)在三维坐标系中建立参考平面；4)根据当前加工叶片、相邻叶片以及刀具参数信息，在参考平面内求解刀轴可摆动区域；5)取刀轴可摆动区域二分角作为初始刀轴矢量；6)利用邻域最小搜索迭代算法对初始刀轴矢量进行优化。本发明提供的方法能够克服常规的曲面加工刀轴控制方法刀具频繁抬刀、刀轴矢量生成复杂多变不光顺的问题。

The invention provides a method for designing a tool axis vector for numerically controlled machining of a curved surface microtexture, comprising the following steps: 1) taking the intersection of a microtexture model guide line or a certain distance offset surface of the microtexture surface as a tool path curve; 2) ) Establish a three-dimensional coordinate system at the tool center point according to the tool path curve, machining direction and the surface information of the original smooth blade; 3) Establish a reference plane in the three-dimensional coordinate system; 4) According to the current processing blade, adjacent blades and tool parameter information , solve the swingable area of the tool axis in the reference plane; 5) take the bisection angle of the swingable area of the tool axis as the initial tool axis vector; 6) optimize the initial tool axis vector by using the neighborhood minimum search iterative algorithm. The method provided by the invention can overcome the problems of frequent tool lifting and complex, variable and unsmooth generation of the tool axis vector in the conventional surface machining tool axis control method.

Description

Design method of curved surface micro-texture numerical control machining cutter shaft vector
Technical Field
The invention relates to the technical field of numerical control machining of curved surface micro-textures, in particular to a design method of a numerical control machining cutter shaft vector of a curved surface micro-texture.
Background
With the development of the bionic surface engineering technology, a plurality of excellent surface performances such as micro-texture drag reduction, wear resistance and the like are proved by more and more researches, but the application and popularization of the bionic surface technology are always limited by complex and low-efficiency manufacturing technologies. Numerical control machining is used as a high-efficiency automatic machining means, and the problems of complex part shape, high precision requirement and the like can be effectively solved.
The design of the micro-texture numerical control cutter shaft vector in the prior art has the following problems:
1) the final calculated arbor feasible region is a cone-like spatial region. However, when a micro-texture is machined by using a five-axis numerical control technology, because the edge angle radius of the cutter is equivalent to the size of the micro-texture, the cutting edge is often embedded between the micro-textures for cutting, so that the swingable area of the cutter shaft of each interpolation point is a fan-shaped plane area instead of a conical space area, that is, when the cutter shaft is used for machining the micro-texture, the trend of the micro-texture at the moment is also considered when the overall interference is considered.
2) The processing objects are all directed to relatively smooth curved surfaces and the curved surfaces generally have uniform parameter distribution. However, the microtextured curved surface is formed by splicing a plurality of curved surfaces, and has no uniform parameterization, so when the cutter shaft calculation method is used, the cutter track feed direction is frequently changed suddenly, a tiny processing section can cause the movement of a cutter to be unstable, and the generated cutter shaft is complex and changeable; moreover, when a continuously undulating microtextured region is machined, if a machining method of a subarea mode is adopted, frequent tool lifting and tool lowering actions are caused, so that not only is the calculation complexity greatly increased and the machining efficiency reduced, but also the feeding mode does not accord with the design intention of an original profile.
3) The optimization target of the cutter shaft is single or the solution is relatively complex. Because the micro-texture has small size, the smoothness of the surface of the micro-texture can be influenced by slight vibration of a machine tool; similarly, the reciprocating change of the tool axis vector under the workpiece coordinate system can also cause the change of the cutting force, and the processing quality of the workpiece surface can be reduced. Therefore, the current cutter shaft control method based on the smooth curved surface is not suitable for processing the complex micro-texture on the curved surface.
Disclosure of Invention
The technical problem to be solved by the invention is to provide a numerical control machining cutter shaft vector design method which can meet the requirement of blade smoothness, avoid cutter interference and machine good micro-texture morphology.
The invention solves the technical problems through the following technical scheme:
the design method of the numerical control machining cutter shaft vector of the curved surface microtexture comprises the following steps:
step 1: determining parameters of the groove type microtexture and the rib type microtexture, and determining the type and the parameters of a used cutter according to the microtexture parameters;
step 2: extracting a tool path curve according to the microtexture model and generating a series of interpolation points on the curve regularly as tool center points;
and step 3: using a tool center point CC on the tool path curveiIf the advancing direction of the cutter is consistent with the parameter increasing direction of the cutter path curve, taking the unit tangent vector t at the cutter center point on the cutter path curve as an X axis, and otherwise, taking the reverse direction of the t as the X axis and passing through the cutter center point CCiMaking a cross section perpendicular to the X axis, the intersection line of the cross section and the surface of the original smooth blade passing through a knife center point CCiThe normal direction of the three-dimensional coordinate system is the Z-axis direction of the coordinate system, and the three-dimensional coordinate system is established according to a right-hand rule;
and 4, step 4: rotating the XOZ plane of the three-dimensional coordinate system established in the step 3 around the X axis by a certain angle to obtain a reference plane;
and 5: the current blade curved surface and the adjacent blade curved surface are biased outwards and oppositely, and a moving point I is respectively taken on the intersecting lines C1 and C2 of the reference plane and the biased curved surface in the step 41And I2Calculated to give point I2Critical cutter axis vector a of2；
Step 6: in step 3, the YOZ plane of the coordinate system and the intersection line C1Between two outer intersection points E and F, a moving point I meeting the judgment condition is searched1And calculates the point of action I1Critical cutter axis vector a of1；
And 7: taking a critical cutter axis vector a2And a1Is taken as the initial cutter axis direction and utilizes the critical cutter axis vector a2And a1Calculating to obtain a cutter axis vector ki；
And 8: sequentially calculating the cutter axis vectors k of all cutter center points on the cutter path curvei1,2, n, using the cutter axis vector as an optimization variable, and kiN is an initial variable value, and is weighted by the variation of the machine rotation axis and the tool machining inclination angleFor optimizing the target, n is the number of the cutter center points; the constraint condition is a critical cutter axis vector a1And a2Establishing optimized mathematical model of cutter axis vector, and setting cutter axis vector kiAnd (6) optimizing.
Preferably, the radius r of the tool in step 1 is equal to the depth of the micro-texture to be processed, and the edge length le2r, and the transition section semicircular cone angle theta is 15 degrees.
Preferably, the method for determining the tool path curve in step 2 is as follows,
for the groove type micro texture, the cutting surface of the micro texture is outwardly biased by the radius of the cutting edge of the cutter, and the intersecting line of each biased surface is taken as the path of the cutter;
for the convex type microtexture, outwardly offsetting the distance of the edge angle radius of the cutter from the cutting surface of the microtexture and the curved surface of the original smooth blade, and taking the intersecting line of each offset surface as a cutter path;
the arc chord error of adjacent cutter center points on the cutter path curve does not exceed the processing error.
Preferably, in step 4, for the groove type microtexture and the rib type microtexture with the triangular cross section, two rotation operations are performed first and then to obtain two reference planes parallel to the two inclined planes of the triangle for each tool center point on the tool path curve, and the tool axis vectors are respectively solved.
Preferably, the leading blade curve and the adjacent blade curve are offset outwardly toward each other by the radius of the shank.
Preferably, in step 5, if there is an intersection between the reference plane and the offset plane of the original smooth curved surface of the adjacent blade, the moving point I is determined2The calculation formula is as follows:
wherein theta is a semicircular cone angle of transition from the blade diameter to the handle diameter of the cutter;
calculating a moving point I according to the formula (1)2If the calculated vector n does not exceed the stroke of the machine tool rotation axis, n is a2；
If the reference plane and the offset plane of the original smooth curved surface of the adjacent blade do not have intersecting lines or the vector n exceeds the stroke of the machine tool rotating shaft, determining the critical cutter shaft vector a at the cutter center point in the reference plane according to the motion transformation relation equation of the cutter shaft vector and the limit coordinate of the machine tool rotating shaft2。
Preferably, step 6 is the moving point I1The judgment conditions are as follows:
wherein,representing straight linesAnd the line of intersection C1There is only one intersection point;
if the moving point I1The vector m is replaced by a direction vector which forms an angle theta in the advancing direction of the tool at the point F of the intersection line C1; if the vector m does not exceed the stroke of the machine tool rotating shaft, m is a1(ii) a Otherwise, determining a in the reference plane according to the motion transformation relation equation of the cutter shaft vector and the limit coordinate of the rotating shaft1。
Preferably, the arbor vector k is calculated in step 7iThe method of (1) is that,
preferably, the mathematical expression of the optimization objective in step 8 is,
wherein u and v are weighting factors of machine tool rotation axis angle change and tool inclination angle change respectively, and u + v is 1; giAnd gammaiThe tool path curve is characterized in that the tool path curve is a machine tool rotating shaft angle change measurement index and a tool inclination angle change measurement index corresponding to the ith and (i + 1) th tool center point, and the expressions are as follows:
wherein (A)i,Ci) Is a curve of the tool pathLast ith cutter center point cutter axis vector kiCorresponding angular coordinate of machine tool rotation axis, (α)i,βi) For the rake angle and the roll angle of the tool in the three-dimensional coordinate system, the calculation method is as follows,
wherein, the point Q is the intersection point of the Z axis and the tool path in the step 3.
Preferably, the solution of the mathematical model optimized in step 8 is,
step i: the critical cutter axis vector a1And a2The swingable areas of the cutter shafts between the cutter shafts are dispersed into m cutter shaft vectors with equal angular intervals, the jth cutter shaft vector of the ith cutter center point is expressed as,
step ii: respectively replacing the m cutter shaft vectors with the initial cutter shaft vectors at the cutter center point, and calculating an optimized target valueTaking the smallest corresponding cutter axis vector in the m optimized target values as an optimized cutter axis vector for iterating the cutter center point for the first time, and sequentially carrying out iteration optimization on all the cutter center points;
step iii: the optimized cutter shaft vector of the cutter center point iterated for the previous time is used as the initial cutter shaft vector of the cutter center point iterated for the next time, and the iterative optimization process is carried out in step ii until the total target value is obtained in the previous and subsequent timesThe difference value of (2) meets the requirement of iteration precision epsilon, and the calculation is stopped.
The design method of the curved surface microtexture numerical control machining cutter shaft vector provided by the invention has the advantages that: by solving the critical cutter shafts on the two sides in the cutter shaft swinging plane, the problem that the conventional curved surface machining cutter shaft control method can generate local interference on the side wall of the micro-texture is well solved; the final cutter shaft vector is generated in the solved cutter shaft swinging area by utilizing a neighborhood minimum search iterative algorithm, so that the processing quality of the micro-texture surface is effectively improved. On the premise of neglecting the technological error caused by the difference between the shape and the size of the cutter and the size of the micro-texture, the good micro-texture morphology can be processed, and a technical method support is provided for the numerical control processing of the micro-texture on the impeller blade.
Drawings
Fig. 1 is a flowchart of a design method of a curved surface microtexture numerical control machining cutter axis vector provided by an embodiment of the invention;
fig. 2 is a schematic diagram of a blade triangular cross-section groove type microtexture of a curved surface microtexture numerical control machining cutter axis vector provided by an embodiment of the invention;
FIG. 3 is a schematic diagram of a triangular section rib type microtexture of a blade with a curved surface microtexture numerically controlled machining cutter axis vector according to an embodiment of the present invention;
fig. 4 is a first critical cutter axis solving diagram of a curved microtexture numerical control machining cutter axis vector provided by the embodiment of the invention;
fig. 5 is a second schematic diagram of solving a critical cutter axis of a curved microtexture numerical control machining cutter axis vector provided by the embodiment of the present invention;
FIG. 6 is a schematic view of a swingable area of a cutter shaft of a curved microtexture numerical control machining cutter shaft vector provided by an embodiment of the present invention;
fig. 7 is a schematic view of a tool machining inclination angle of a curved microtexture numerical control machining tool axis vector provided by an embodiment of the present invention.
In the figure:
1-tool path curve;
2-intersection line of surface and original smooth blade surface;
3-a reference plane;
4-original smooth blade surface;
5-microtextured cut surface;
6-triangular cross-section groove ridge line in fig. 1;
7-impeller hub surface;
8-offset plane of current blade or adjacent blade;
9-blade surface.
Detailed Description
In order that the objects, technical solutions and advantages of the present invention will become more apparent, the present invention will be further described in detail with reference to the accompanying drawings in conjunction with the following specific embodiments.
As shown in fig. 1, a design method of a curved surface microtexture numerical control machining cutter shaft vector comprises the following steps:
step 1: determining parameters of the groove type microtexture and the rib type microtexture, and determining the type and the parameters of a used cutter according to the microtexture parameters; the cutter is preferably a ball-end cutter, the radius r of the cutter is equal to the depth of the processed microtexture, and the edge length l of the cuttereAnd 2r, the semi-circle taper angle theta of the transition section is 15 degrees.
Step 2: extracting a tool path curve according to the microtexture model and generating a series of interpolation points on the curve regularly as a tool center point, wherein the tool center point is the spherical center of the cutting edge of the ball-nose tool, namely the point through which the spherical center of the ball-nose tool passes;
referring to fig. 2, for a groove type microtexture, the microtexture cutting face is outwardly offset by the distance of the radius of the cutting edge of the cutter, with the intersection of the offset faces as the cutter path curve;
referring to fig. 3, for the convex type microtexture, the microtexture cutting surface and the original smooth blade curved surface are outwardly offset by the distance of the knife edge angle radius, and the intersecting line of each offset surface is taken as a knife path curve.
The knife center point generation rule is as follows: and generating a series of tool center points on the extracted tool path curve according to the principle that the arc chord error between adjacent tool center points does not exceed the machining error requirement. The smaller the arc chord error between adjacent cutter center points is, the smaller the machining error is.
And step 3: using a tool center point CC on the tool path curveiIf the advancing direction of the cutter is consistent with the parameter increasing direction of the cutter path curve, taking the unit tangent vector t at the cutter center point on the cutter path curve as an X axis, and otherwise, taking the reverse direction of the t as the X axis and passing through the cutter center point CCiMaking a cross section perpendicular to the X axis, the intersection line of the cross section and the surface of the original smooth blade passing through a knife center point CCiThe normal direction of the three-dimensional coordinate system is the Z-axis direction of the coordinate system, and the three-dimensional coordinate system is established according to a right-hand rule;
and 4, step 4: rotating the XOZ plane of the three-dimensional coordinate system established in the step 3 around the X axis by a certain angle to obtain a reference plane; for the micro-texture with the groove type and the rib type of the triangular section, aiming at each cutter center point on the cutter path curve, two times of rotation operations are firstly and secondly executed to obtain two reference planes which are respectively parallel to two inclined planes of the triangle, and cutter axis vectors are respectively solved.
And 5: referring to fig. 4 and 5, the current blade curved surface and the adjacent blade curved surface are outwardly biased toward each other by the radius R of the tool shank, and a moving point I is respectively taken on the intersecting lines C1 and C2 of the reference plane and the offset curved surface in step 41And I2Calculated to give point I2Critical cutter axis vector a of2；
If the reference plane and the offset plane of the original smooth curved surface of the adjacent blade have an intersection line, the moving point I2The calculation formula is as follows:
wherein theta is a semicircular cone angle of transition from the blade diameter to the handle diameter of the cutter;
calculating a moving point I according to the formula (1)2If the calculated vector n does not exceed the stroke of the machine tool rotation axis, n is a2；
If the reference plane and the offset plane of the original smooth curved surface of the adjacent blade do not have intersecting lines or the vector n exceeds the stroke of the machine tool rotating shaft, determining the critical cutter shaft vector a at the cutter center point in the reference plane according to the motion transformation relation equation of the cutter shaft vector and the limit coordinate of the machine tool rotating shaft2。
Step 6: in step 3, the YOZ plane of the coordinate system and the intersection line C1Between two outer intersection points E and F, a moving point I meeting the judgment condition is searched1And calculates the point of action I1Critical cutter axis vector a of1；
The judgment conditions are as follows:
wherein,representing straight linesAnd the line of intersection C1There is only one intersection point;
if the moving point I1The vector m is replaced by a direction vector which forms an angle theta in the advancing direction of the tool at the point F of the intersection line C1; if the vector m does not exceed the stroke of the machine tool rotating shaft, m is a1(ii) a Otherwise, according to the motion transformation relation equation of the cutter shaft vector and the limit coordinate of the machine tool rotating shaft,determining a in the reference plane1。
And 7: taking a critical cutter axis vector a2And a1Is taken as the initial cutter axis direction and utilizes the critical cutter axis vector a2And a1Calculating to obtain an initial cutter axis vector kiThe calculation method is as follows,
and 8: referring to fig. 6, the tool axis vectors k of all the tool center points on the tool path curve are sequentially calculatedi1,2, n, using the cutter axis vector as an optimization variable, and kiN is an initial variable value, and is weighted by the variation of the machine rotation axis and the tool machining inclination angleFor optimizing the target, n is the number of the cutter center points; the constraint condition is a critical cutter axis vector a1And a2Establishing optimized mathematical model of cutter axis vector, and setting cutter axis vector kiAnd (6) optimizing.
The mathematical expression of a specific optimization objective is,
u and v are weighting factors of machine tool rotation axis angle change and tool inclination angle change, respectively, and u + v is 1, and the specific value thereof can be determined by those skilled in the art according to the actual microtexture type, machine tool structure and machining process requirements, generally, u is 0.5, and if it is desired that the influence of machine tool rotation axis angle change or tool inclination angle change on the microtexture surface is large, the value of u or v may be correspondingly increased; giAnd gammaiRespectively measuring the angle change of the machine tool rotating shaft and the inclination angle of the tool corresponding to the ith and the (i + 1) th tool center points on the tool path curveThe change metric index is expressed as:
wherein (A)i,Ci) Is the ith cutter center point cutter axis vector k on the cutter path curveiCorresponding angular coordinate of machine tool rotation axis, (α)i,βi) Referring to fig. 6, for the rake angle and the roll angle of the tool in the three-dimensional coordinate system, the calculation method is as follows,
wherein, the point Q is the intersection point of the Z axis and the tool path in the step 3.
The solution process of the optimized mathematical model comprises the following steps:
step i: the critical cutter axis vector a1And a2The swingable areas of the cutter shafts between the cutter shafts are dispersed into m cutter shaft vectors with equal angular intervals, the jth cutter shaft vector of the ith cutter center point is expressed as,
step ii: respectively replacing the m cutter shaft vectors with the initial cutter shaft vectors at the cutter center point, and calculating an optimized target valueTaking the smallest corresponding cutter axis vector in the m optimized target values as an optimized cutter axis vector for iterating the cutter center point for the first time, and sequentially carrying out iteration optimization on all the cutter center points;
step iii: the optimized cutter shaft vector of the cutter center point is iterated for the last time, namely the initial cutter shaft vector of the cutter center point is iterated for the next time, and the iterative optimization process is carried out by repeating the step ii until the total target value is obtained for the previous time and the next timeThe difference value of (2) meets the requirement of iteration precision epsilon, and the calculation is stopped.
The user can set the numerical value of the iteration precision epsilon according to specific conditions and requirements, the smaller the iteration precision epsilon is, the more the iteration result is, and the more the iteration times are, the larger the calculated amount is.
In the embodiment, the impeller is implemented by about 110mm, the cross section of the groove of the microtexture is a regular triangle, the depth is about 0.2mm, the groove is positioned in the front half part of the pressure surface of the blade, the direction is approximately vertical to the flow direction of the fluid, the radius r of the edge angle of the ball head cutter used for processing the microtexture of the groove is 0.2mm, and the length l of the edge is longeThe radius R of the tool shank is 3mm, and the radius theta of the transition section semicircular cone angle theta is 15 degrees.
The micro-texture rib section is a regular triangle with the height of about 0.3mm, and is positioned on one side of the suction surface of the blade, the rib direction of the front half part is approximately vertical to the fluid flow direction, and the rib direction of the rear half part is approximately parallel to the fluid flow direction; the radius r of the edge angle of the ball-end cutter used for processing the rib micro texture is 0.3mm, and the length l of the edgeeThe radius R of the tool shank is 4mm, and the radius theta of the transition section semicircular cone angle theta is 15 degrees.
The machine tool is an AC-axis double-swing-table machine tool of a Demaji ULTRASONIC 20linear model, the maximum rotation angle of an A axis of a rotating shaft is set to be 120 degrees, a discrete region of a cutter shaft is divided into m-50 cutter shaft vectors, a weight factor u-v-0.5, and an iteration precision epsilon-0.001.
Verifying the result of the design method for the numerical control machining cutter axis vector of the curved surface microtexture provided by the embodiment by using VERICUT simulation and NXOpen C + + secondary development, as shown in tables 1 and 2; it can be known that the optimized cutter shaft does not interfere with adjacent blades, and the target value after optimization is reduced by 20%, so that the fluctuation range of the machine tool rotating shaft is reduced, and the cutting condition of the microtexture is improved.
TABLE 1 Critical cutter shaft and optimized front and rear cutter shaft vectors at numerical control machining cutter center point of groove
TABLE 2 target values for each iteration
Number of iterations 0 1 2 3 4 5
Total target value 22.885 21.031 20.139 18.989 18.557 18.063
Number of iterations 6 7 8 9 10 11
Total target value 18.035 18.015 18.008 17.998 17.988 17.988
The above-mentioned embodiments, objects, technical solutions and advantages of the present invention are further described in detail, it should be understood that the above-mentioned embodiments are only examples of the present invention, and are not intended to limit the present invention, and any modifications, equivalent substitutions, improvements and the like made by those skilled in the art without departing from the spirit and principles of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims (10)

1.曲面微织构数控加工刀轴矢量的设计方法，其特征在于：包括以下步骤：1. The design method of the NC machining tool axis vector of curved surface micro-texture is characterized in that: comprise the following steps: 步骤1：确定沟槽型微织构和肋条型微织构的参数，并根据微织构参数确定使用的刀具类型和参数；Step 1: Determine the parameters of groove-type microtexture and rib-type microtexture, and determine the type and parameters of the tool used according to the microtexture parameters; 步骤2：根据微织构模型提取刀具路径曲线并在曲线上规则生成一系列插补点作为刀心点；Step 2: Extract the tool path curve according to the microtexture model and regularly generate a series of interpolation points on the curve as the tool center point; 步骤3：以刀具路径曲线上一刀心点CCi为原点，如果刀具的前进方向和刀具路径曲线的参数增加方向一致，取刀具路径曲线上该刀心点处的单位切矢t为X轴，否则取t的反方向为X轴，过刀心点CCi做垂直于X轴的截面，该截面和原光滑叶片表面的交线经过刀心点CCi的法线方向为坐标系的Z轴方向，根据右手法则建立三维坐标系；Step 3: Take the tool center point CC i on the tool path curve as the origin, if the forward direction of the tool is consistent with the parameter increase direction of the tool path curve, take the unit tangent vector t at the tool center point on the tool path curve as the X axis, Otherwise, take the opposite direction of t as the X-axis, and make a cross-section perpendicular to the X-axis through the tool center point CC i . The normal direction of the intersection line of the cross-section and the original smooth blade surface passing through the tool center point CC i is the Z-axis of the coordinate system. direction, establish a three-dimensional coordinate system according to the right-hand rule; 步骤4：以步骤3建立的三维坐标系的XOZ平面为基面，围绕X轴旋转一定角度，得到参考平面；Step 4: Take the XOZ plane of the three-dimensional coordinate system established in step 3 as the base plane, and rotate around the X axis by a certain angle to obtain the reference plane; 步骤5：将当前叶片曲面和相邻叶片曲面向外相向偏置，在步骤4的参考平面与偏置曲面的交线C1和C2上分别取一动点I1和I2，计算得到在点I2处的临界刀轴矢量a2；Step 5: Offset the current blade surface and the adjacent blade surface toward each other, take a moving point I 1 and I 2 on the intersection lines C1 and C2 of the reference plane and the offset surface in step 4, and calculate the point I critical tool axis vector a 2 at 2 ; 步骤6：在步骤3坐标系的YOZ平面与交线C1的外侧的两个交点E和F之间寻找满足判断条件的动点I1并计算在动点I1处的临界刀轴矢量a1；Step 6: Find the moving point I 1 that satisfies the judgment conditions between the YOZ plane of the step 3 coordinate system and the two intersections E and F outside the intersection line C 1 and calculate the critical tool axis vector a at the moving point I 1 1 ; 步骤7：取临界刀轴矢量a2和a1的二分角方向作为初始刀轴方向，并利用临界刀轴矢量a2和a1计算得到刀轴矢量ki；Step 7: take the direction of the bisection angle of the critical tool axis vectors a 2 and a 1 as the initial tool axis direction, and use the critical tool axis vectors a 2 and a 1 to calculate the tool axis vector k i ; 步骤8：依次计算出刀具路径曲线上所有刀心点的刀轴矢量ki,i＝1,2,...,n，以刀轴矢量为优化变量，以ki,i＝1,2,...,n为变量初始值，以机床旋转轴以及刀具加工倾角的变化量加权和为优化目标，n为刀心点数量；约束条件为临界刀轴矢量a1和a2，建立刀轴矢量的优化数学模型，对刀轴矢量ki进行优化。Step 8: Calculate the tool axis vectors k i , i=1,2,...,n of all the tool center points on the tool path curve in turn, take the tool axis vector as the optimization variable, and take k i , i=1,2 ,...,n is the initial value of the variable, which is the weighted sum of the variation of the machine tool rotation axis and the machining inclination of the tool In order to optimize the objective, n is the number of tool center points; the constraints are the critical tool axis vectors a 1 and a 2 , establish the optimization mathematical model of the tool axis vector, and optimize the tool axis vector ki . 2.根据权利要求1所述的曲面微织构数控加工刀轴矢量的设计方法，其特征在于：步骤1中的刀具选用半径r与所加工的微织构深度相等，刃长le＝2r，过渡段半圆锥角θ＝15°的球头刀。2. the design method of the numerical control machining tool axis vector of curved surface microtexture according to claim 1, it is characterized in that: the tool selection radius r in the step 1 is equal to the microtexture depth processed, and the blade length le =2r , the transition section semi-conical angle θ = 15 ° ball nose knife. 3.根据权利要求2所述的曲面微织构数控加工刀轴矢量的设计方法，其特征在于：步骤2中确定刀具路径曲线的方法如下，3. the design method of surface micro-texture numerical control machining tool axis vector according to claim 2, is characterized in that: in step 2, the method for determining tool path curve is as follows, 对于沟槽类型的微织构，将微织构切削面向外偏置刀具刀刃半径的距离，以各个偏置面的交线作为刀具路径；For groove-type microtexture, offset the cutting surface of the microtexture outward by the distance of the tool edge radius, and take the intersection of each offset surface as the tool path; 对于凸起类型的微织构，将微织构切削面和原光滑叶片曲面向外偏置刀具刃角半径的距离，以各偏置面的交线作为刀具路径；For the convex type microtexture, offset the cutting surface of the microtexture and the surface of the original smooth blade by the distance of the radius of the tool edge, and take the intersection of the offset surfaces as the tool path; 在刀具路径曲线上相邻刀心点的弧弦误差不超出加工误差。The arc chord error of adjacent tool center points on the tool path curve does not exceed the machining error. 4.根据权利要求1所述的曲面微织构数控加工刀轴矢量的设计方法，其特征在于：步骤4中对于三角形截面沟槽类型的微织构和肋条类型的微织构，针对刀具路径曲线上的每个刀心点，先后执行两次旋转操作得到两个分别与三角形两个斜面平行的参考平面，并分别求解刀轴矢量。4. the design method of the numerical control machining tool axis vector of curved surface microtexture according to claim 1, is characterized in that: in step 4, for the microtexture of triangular cross-section groove type and the microtexture of rib type, for the tool path For each tool center point on the curve, perform two rotation operations successively to obtain two reference planes parallel to the two inclined surfaces of the triangle, and solve the tool axis vector respectively. 5.根据权利要求2所述的曲面微织构数控加工刀轴矢量的设计方法，其特征在于：当前叶片曲面和相邻叶片曲面向外相向偏置刀柄半径的距离。5 . The method for designing the NC machining tool axis vector of curved surface microtexture according to claim 2 , wherein: the current blade curved surface and the adjacent blade curved surface are offset by the distance of the tool shank radius outwards. 6 . 6.根据权利要求1所述的曲面微织构数控加工刀轴矢量的设计方法，其特征在于：步骤5中，如果参考平面与相邻叶片的原光滑曲面的偏置面存在交线，则动点I2计算公式如下：6. The design method of the numerical control machining tool axis vector of curved surface microtexture according to claim 1, it is characterized in that: in step 5, if the reference plane and the offset surface of the original smooth curved surface of the adjacent blade have an intersection, then The formula for calculating the moving point I 2 is as follows: 其中，θ为刀具刃径到柄径过渡的半圆锥角；Among them, θ is the semi-conical angle of the transition from the tool blade diameter to the shank diameter; 根据公式(1)计算出一动点I2，若计算出的矢量n未超出机床旋转轴行程，则n＝a2；Calculate a moving point I 2 according to formula (1), if the calculated vector n does not exceed the travel of the machine tool rotation axis, then n=a 2 ; 若参考平面与相邻叶片的原光滑曲面的偏置面没有交线或矢量n超出机床旋转轴行程，则根据刀轴矢量与机床旋转轴极限坐标的运动变换关系方程在该参考平面内确定该刀心点处的临界刀轴矢量a2。If there is no intersection between the reference plane and the offset surface of the original smooth surface of the adjacent blade or the vector n exceeds the travel of the machine tool rotation axis, then determine the reference plane according to the motion transformation equation between the tool axis vector and the limit coordinates of the machine tool rotation axis. The critical tool axis vector a 2 at the tool center point. 7.根据权利要求6所述的曲面微织构数控加工刀轴矢量的设计方法，其特征在于：步骤6中动点I1的判断条件为：7. the design method of curved surface micro-texture numerical control machining tool axis vector according to claim 6, is characterized in that: in step 6, the judgment condition of moving point I 1 is: 其中，表示直线与交线C1只有一个交点；in, represents a straight line There is only one point of intersection with the intersection line C1 ; 若此动点I1在交线C1端点F处取得，则用于此处刀具前进方向上成θ角度的方向矢量取代计算出的矢量m；若矢量m未超出机床旋转轴行程，则m＝a1；否则根据刀轴矢量与旋转轴极限坐标的运动变换关系方程，在该参考平面内确定a1。If the moving point I 1 is obtained at the end point F of the intersection line C1, the direction vector at the angle θ in the forward direction of the tool is used to replace the calculated vector m; if the vector m does not exceed the travel of the machine tool rotation axis, then m= a 1 ; otherwise, determine a 1 in the reference plane according to the equation of motion transformation between the tool axis vector and the limit coordinates of the rotation axis. 8.根据权利要求1所述的曲面微织构数控加工刀轴矢量的设计方法，其特征在于：步骤7中计算刀轴矢量ki的方法为，8. the design method of curved surface micro-texture numerical control machining tool axis vector according to claim 1, is characterized in that: in step 7, the method for calculating tool axis vector k i is, 9.根据权利要求1所述的曲面微织构数控加工刀轴矢量的设计方法，其特征在于：步骤8中优化目标的数学表达式为，9. the design method of the surface micro-texture numerical control machining tool axis vector according to claim 1, is characterized in that: the mathematical expression of optimization target in step 8 is, 其中，u和v分别为机床旋转轴角度变化和刀具倾角变化的权重因子，且u+v＝1；Gi和γi分别为刀具路径曲线上第i个和第i+1个刀心点对应的机床旋转轴角度变化度量指标和刀具倾角变化度量指标，其表达式为：Among them, u and v are the weight factors for the change of the machine tool rotation axis angle and the tool inclination angle, respectively, and u+v=1; G i and γ i are the i-th and i+1-th tool center points on the tool path curve, respectively The corresponding metric index of machine tool rotation axis angle change and tool inclination change metric index are expressed as: 其中，(Ai,Ci)为刀具路径曲线上第i个刀心点刀轴矢量ki对应的机床旋转轴的角度坐标，(αi,βi)为三维坐标系中的刀具前倾角和侧倾角，计算方法如下，Among them, (A i , C i ) is the angular coordinate of the machine tool rotation axis corresponding to the tool axis vector k i of the i-th tool center point on the tool path curve, (α i , β i ) is the tool rake angle in the three-dimensional coordinate system and the roll angle, calculated as follows, 其中，点Q为步骤3中Z轴与刀具路径的交点。Among them, the point Q is the intersection of the Z axis and the tool path in step 3. 10.根据权利要求9所述的面微织构数控加工刀轴矢量的设计方法，其特征在于：步骤8中优化的数学模型的求解过程为，10. the design method of surface microtexture numerical control machining tool axis vector according to claim 9, is characterized in that: the solution process of the mathematical model optimized in step 8 is, 步骤i：将临界刀轴矢量a1与a2之间的刀轴可摆动区域离散为等角度间隔的m个刀轴矢量，第i个刀心点的第j个刀轴矢量表示为，Step i: Discrete the swingable area of the tool axis between the critical tool axis vectors a 1 and a 2 into m tool axis vectors at equal angular intervals, and the jth tool axis vector of the ith tool center point is expressed as, 步骤ii：分别将m个刀轴矢量取代该刀心点处的初始刀轴矢量，并计算优化目标值将m个优化目标值中最小的一个对应的刀轴矢量，作为第一次迭代该刀心点的优化刀轴矢量，依次对所有刀心点进行迭代优化；Step ii: Replace the initial tool axis vector at the tool center point with m tool axis vectors respectively, and calculate the optimized target value Take the tool axis vector corresponding to the smallest one of the m optimization target values as the optimized tool axis vector of the tool center point in the first iteration, and perform iterative optimization on all the tool center points in turn; 步骤iii：以上一次迭代该刀心点的优化刀轴矢量作为下一次迭代该刀心点的初始刀轴矢量，步骤ii进行迭代优化过程，直到前后两次总目标值的差值满足迭代精度ε要求，停止计算。Step iii: The optimized tool axis vector of the tool center point in the previous iteration is used as the initial tool axis vector of the tool center point in the next iteration, and the iterative optimization process is carried out in step ii until the total target value of the two front and back times is reached. The difference of satisfies the requirement of iterative accuracy ε, and the calculation is stopped.
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