CN109597355B - Design method of curved surface micro-texture numerical control machining cutter shaft vector - Google Patents
Design method of curved surface micro-texture numerical control machining cutter shaft vector Download PDFInfo
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Abstract
The invention provides a design method of a curved surface microtexture numerical control machining cutter shaft vector, which comprises the following steps: 1) taking the intersection line of the guide line of the micro-texture model or the offset plane of the micro-texture surface at a certain distance as a cutter path curve; 2) establishing a three-dimensional coordinate system at the cutter center point according to the cutter path curve, the processing direction and the curved surface information of the original smooth blade; 3) establishing a reference plane in a three-dimensional coordinate system; 4) solving a cutter shaft swingable area in a reference plane according to the currently processed blade, the adjacent blade and the cutter parameter information; 5) taking a bisection angle of a swingable area of a cutter shaft as an initial cutter shaft vector; 6) and optimizing the initial cutter axis vector by using a neighborhood minimum search iterative algorithm. The method provided by the invention can overcome the problems of frequent cutter lifting and complicated and changeable cutter shaft vector generation in the conventional curved surface processing cutter shaft control method.
Description
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 curve i1,2, 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 angle
For 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 the content of the first and second substances,
representing straight lines
And the line of intersection C1There is only one intersection point;
if the moving point I1Taken at point F of intersection C1,replacing the calculated vector m with a direction vector for forming an angle theta in the advancing direction of the cutter; 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 the ith cutter center point cutter axis vector k on the cutter path curveiCorresponding angular coordinate of machine tool rotation axis (alpha)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 value
Taking 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 times
The 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 the content of the first and second substances,
representing straight lines
And 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 machine tool rotating shaft1。
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 angle
For 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,
wherein u and v are respectively machine tool spindlesThe specific value of u + v is 1, which can be determined by a person skilled in the art according to the actual microtexture type, the machine tool structure and the machining process requirements, generally, u + v is 0.5, and if the influence of the machine tool rotation shaft angle change or the cutter inclination angle change on the microtexture surface is expected to be large, the value of u or v is increased correspondingly; 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 the ith cutter center point cutter axis vector k on the cutter path curveiCorresponding angular coordinate of machine tool rotation axis (alpha)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 value
Taking 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 time
The 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 |
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 (5)
1. The design method of the numerical control machining cutter shaft vector of the curved surface microtexture is characterized by comprising the following steps of: the method 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; for the micro-texture of the groove type and the micro-texture of the rib type with the triangular section, aiming at each cutter center point on the cutter path curve, firstly and secondly performing two times of rotation operation to obtain two reference planes which are respectively parallel to two inclined planes of the triangle, and respectively solving cutter axis vectors;
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
And 8: sequentially calculating all the curve lines of the tool pathCutter axis vector k of cutter center pointi1,2, n, using the cutter axis vector as an optimization variable, and weighting and summing the quantities of variation of the machine tool rotation axis and the machining inclination angle of the cutter
For 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 kiOptimizing;
in step 5, 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 formula2If 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 moving point I1The judgment conditions are as follows:
wherein the content of the first and second substances,
representing straight lines
And 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；
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 the ith cutter center point cutter axis vector k on the cutter path curveiCorresponding angular coordinate of machine tool rotation axis (alpha)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.
2. The design method of the curved surface microtexture numerical control machining cutter shaft vector according to claim 1, characterized in that: the radius r of the cutter in the step 1 is equal to the depth of the processed micro-texture, and the edge length le2r, and the transition section semicircular cone angle theta is 15 degrees.
3. The design method of the curved surface microtexture numerical control machining cutter shaft vector as claimed in claim 2, characterized in that: 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 rib type micro texture, the cutting surface of the micro texture and the curved surface of the original smooth blade are outwardly offset by the radius of the edge angle of the cutter, and the intersecting line of each offset surface is used as a cutter path;
the arc chord error of adjacent cutter center points on the cutter path curve does not exceed the processing error.
4. The design method of the curved surface microtexture numerical control machining cutter shaft vector as claimed in claim 2, characterized in that: the current blade curved surface and the adjacent blade curved surface are outwardly and oppositely offset by the radius of the tool shank.
5. The design method of the curved surface microtexture numerical control machining cutter shaft vector according to claim 1, characterized in that: the solution process of the optimized mathematical model 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 combine mThe cutter shaft vector replaces the initial cutter shaft vector at the cutter center point, and the optimized target value is calculated
Taking 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 times
The difference value of (2) meets the requirement of iteration precision epsilon, and the calculation is stopped.
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