A control line-based tool axis control method for five-axis CNC machining of impeller annular cutters

Abstract

The invention discloses a control line-based tool axis control method for five-axis CNC machining of an impeller annular tool. The method comprises the following steps: determining a feasible domain of non-interference tool axis control points according to a contact point on a machining blade profile; finding an intersection of the feasible domains of non-interference tool axis control points corresponding to the contact points on each machining trajectory on the machining blade profile to obtain a feasible domain of non-interference common tool axis control points for each machining trajectory; generating a non-interference tool axis control line in the feasible domain of non-interference common tool axis control points; calculating a corresponding tool center point according to each control point on the non-interference tool axis control line and the corresponding contact point; the invention adopts an annular tool to machine an impeller, which can effectively alleviate tool wear, reduce operation complexity, and improve the surface quality of a workpiece; and the tool axis produced by the control line does not depend on the surface parameter characteristics, and the tool axis changes smoothly, thus avoiding the phenomenon of obvious tool joint marks caused by machining in different areas.

Description

Technical Field

[0001] The invention relates to the field of numerical control machining, and in particular to a tool axis control method for five-axis numerical control machining of an impeller annular cutter based on a control line. Background Art

[0002] Centrifugal impellers are increasingly used in modern defense, energy and other civilian fields, with typical examples being turboshaft aircraft engines, air compressors, ventilators, etc. High-efficiency and precision CNC machining technology for such parts has become one of the important manifestations of the core competitiveness of advanced manufacturing companies.

[0003] In order to achieve excellent aerodynamic performance of the impeller flow channel during high-speed rotation of the impeller, the centrifugal impeller structure adopts a three-dimensional flow design method, with a large blade profile twist angle, a narrow and long flow channel, and a blade with variable thickness and a variable rounded corner transition. The inlet edge of the impeller blade is basically perpendicular to the impeller rotation axis, while the exhaust edge is basically parallel to the rotation axis. The radial direction of the blade from the inlet edge to the exhaust edge along the flow channel gradually transitions from being basically perpendicular to the impeller rotation axis to being basically parallel to the rotation axis. This complex structure requires the use of a five-axis CNC machine tool for CNC machining of the impeller. In five-axis machining, if the tool axis vector changes dramatically, the machine tool's rotation axis will produce a large angular velocity and angular acceleration. A large number of engineering practices have shown that excessive angular angular velocity and angular acceleration of the machine tool's rotation axis will seriously affect the quality of the machined surface. Therefore, tool axis control in five-axis CNC machining of impellers is particularly important.

[0004] During the machining of impellers, the tool wears seriously due to the difficult machining characteristics of the material. When using a ball-end tool, the contact area between the ball-end tool and the workpiece surface is large, the wear is serious, and the tool must be changed many times during machining. The current solution to this problem is to process in different areas. However, the operation of the process of processing in different areas is complicated, which not only increases the machining cost, but also causes obvious tool connection marks between different areas, reducing the surface quality of the workpiece. Summary of the invention

[0005] The purpose of the present invention is to provide a control line-based impeller annular cutter five-axis CNC machining tool axis control method, which uses an annular cutter to process the impeller, can effectively alleviate the wear of the tool, reduce the complexity of operation, and improve the surface quality of the workpiece.

[0006] The present invention adopts the following technical solution: a control line-based impeller annular cutter five-axis CNC machining tool axis control method, comprising the following steps:

[0007] According to the contact points on the processed blade surface, the corresponding feasible domain of the non-interference tool axis control points is determined;

[0008] The intersection of the feasible domains of non-interference tool axis control points corresponding to the cutting contact points on each machining trajectory on the machining blade profile is calculated to obtain the feasible domain of non-interference common tool axis control points of each machining trajectory;

[0009] Generate non-interference tool axis control lines in the feasible domain of non-interference common tool axis control points;

[0010] The corresponding tool center point is calculated based on each control point on the non-interference tool axis control line and the corresponding cutting contact point.

[0011] Furthermore, the feasible domain of the corresponding non-interference tool axis control points is determined to include:

[0012] Determine the corresponding annular blade center point according to the cutting contact point on the processed blade profile;

[0013] Determine the initial domain of the center point of the annular knife on a spherical surface with the center point of the blade as the center of the sphere and (R1-R2) as the radius; wherein R1 is the radius of the annular knife and R2 is the radius of the bottom edge of the annular knife;

[0014] A first offset surface and a second offset surface are generated respectively according to the machining blade profiles and adjacent blade profiles on both sides of the machining channel, and a tool center point feasible domain surface without interference is generated in the tool center point initial domain by using the first offset surface and the second offset surface;

[0015] Generate an auxiliary surface according to the first offset surface and the second offset surface, and project the feasible domain surface of the tool center point onto the auxiliary surface to obtain the feasible domain of the non-interference tool axis control point corresponding to the blade center point A;

[0016] The feasible domain of the non-interference tool axis control points corresponding to the blade center point A is taken as the feasible domain of the non-interference tool axis control points of the cutting contact point.

[0017] Further, generating a tool center point feasible domain surface without interference in the tool center point initial domain by using the first offset surface and the second offset surface includes:

[0018] Discretize the initial domain of the knife center point into a number of arcs of equal height;

[0019] Select the point O' corresponding to each contour arc on the normal vector extension line of the tangent contact point 2,i , to satisfy Among them, A is the blade center point corresponding to the cutting contact point, O 2,i is a point on the contour arc;

[0020] Using Point O' 2,i Generate several tool axis lines with points on the contour arc;

[0021] Points on the contour arc corresponding to the tool axis line which does not intersect the first offset surface and the second offset surface are selected to form a tool center point feasible domain surface without interference.

[0022] Further, generating the auxiliary curved surface according to the first offset surface and the second offset surface includes:

[0023] The edge line of the first offset surface is offset radially outward along the impeller rotation axis to obtain a first offset curve;

[0024] The first offset curve is rotated around the impeller rotation axis to a predetermined position to obtain an auxiliary curved surface; wherein the predetermined position is a projection position of an edge line of the second offset surface on the rotation path of the first offset curve.

[0025] Furthermore, projecting the feasible domain surface of the tool center point onto the auxiliary surface includes:

[0026] Discretize the normal vector direction of the contact point on the feasible domain surface of the tool center point to obtain several non-interference tool center point trajectory lines;

[0027] The point O' corresponding to the contour arc where the non-interference tool center point trajectory line is located 2,i The projection point is used to project the point on the trajectory line of the non-interference tool center point onto the auxiliary surface.

[0028] Further, generating the first offset surface and the second offset surface respectively according to the processed blade profiles and adjacent blade profiles on both sides of the processing channel includes:

[0029] Offset the processed blade profile to the processing channel direction by R1;

[0030] Offset the adjacent blade profiles by R1 in the direction of the machining channel.

[0031] Furthermore, the optimization principles for generating non-interference tool axis control lines in the feasible domain of non-interference common tool axis control points include:

[0032] The cumulative arc length of the non-interference tool axis control line is the shortest and the curvature change is the smallest.

[0033] Further, calculating the corresponding tool center point according to each control point on the non-interference tool axis control line and the corresponding cutting contact point includes:

[0034] Determine the cutting edge point of the tool based on the control point and the cutting contact point;

[0035] Generate a spherical surface S with the blade center as the sphere center and (R2-R1) as the radius A ;

[0036] Generate a spherical surface S with the line connecting the control point and the blade center point as the diameter and the center of the line as the center. B ;

[0037] According to the spherical surface S A and spherical surface S B Determine the center point of the knife.

[0038] Further, according to the spherical surface S A and spherical surface S B Determining the knife center point includes:

[0039] According to the spherical surface S A and spherical surface S B Determine the space curve circle l O ;

[0040] Determine the plane ∑ according to the control point, the tangent contact point and the surface normal vector at the tangent contact point;

[0041] Based on the space curve circle l O Calculate the tool center point with plane∑.

[0042] Another technical solution of the present invention: a control line-based impeller annular cutter five-axis CNC machining tool axis control method, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the above-mentioned control line-based impeller annular cutter five-axis CNC machining tool axis control method is implemented.

[0043] The beneficial effects of the present invention are as follows: the present invention adopts an annular cutter to process the impeller, which can effectively alleviate the wear of the tool, reduce the complexity of operation, and improve the surface quality of the workpiece. The tool axis produced by the control line does not depend on the surface parameter characteristics, and the tool axis changes smoothly, avoiding the obvious tool mark caused by area processing. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 Schematic diagram of the initial domain of the center point of the ring knife in an embodiment of the present invention;

[0045] Figure 2 Schematic diagram of the discrete model of the initial feasible domain of the ring knife in the embodiment of the present invention;

[0046] Figure 3 Schematic diagram of three situations of non-interference tool center point interference determination in an embodiment of the present invention;

[0047] Figure 4 is a schematic diagram of an auxiliary curved surface in an embodiment of the present invention;

[0048] Figure 5 It is a schematic diagram of the feasible domain of the non-interference tool axis control point on the auxiliary surface in an embodiment of the present invention;

[0049] Figure 6 This is a schematic diagram of an initial control line in an embodiment of the present invention;

[0050] Figure 7 Schematic diagram of the optimization model of the cutter axis control line of the annular cutter in the embodiment of the present invention;

[0051] Figure 8 Schematic diagram of the cutting contact model of the annular knife processing in the embodiment of the present invention;

[0052] Fig. 9 Schematic diagram of knife center point solution based on control line in an embodiment of the present invention;

[0053] Fig.10 This is a model diagram for solving the center point of the ring knife in an embodiment of the present invention;

[0054] Fig.11 This is a diagram showing the changing rules of the kinematic variables of the machine tool of the present invention. DETAILED DESCRIPTION

[0055] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0056] In view of the difficulties in impeller channel processing, the present invention generates a tool axis vector by constructing a circular tool axis control line. The tool axis control method does not depend on the curved surface. As long as the tool axis control line is smooth, the generated tool axis is also smooth. The method can effectively solve the blade gnawing problem caused by tool axis interference and tool axis mutation in impeller processing, and significantly improve the processing quality of the blade surface.

[0057] The invention discloses a control line-based five-axis CNC machining tool axis control method for an impeller annular tool, comprising the following steps: determining the corresponding feasible domain of non-interference tool axis control points according to the tangent contact points on the machining blade profile; finding the intersection of the feasible domain of non-interference tool axis control points corresponding to the tangent contact points on each machining trajectory on the machining blade profile to obtain the feasible domain of non-interference common tool axis control points for each machining trajectory; generating non-interference tool axis control lines in the feasible domain of non-interference common tool axis control points; and calculating the corresponding tool center point according to each control point on the non-interference tool axis control line and the corresponding tangent contact point.

[0058] The present invention uses an annular cutter to process the impeller, which can effectively alleviate the wear of the tool, reduce the complexity of operation, and improve the surface quality of the workpiece. The tool axis produced by the control line does not depend on the surface parameter characteristics, and the tool axis changes smoothly, avoiding the obvious tool mark caused by area processing.

[0059] In one embodiment, determining the corresponding feasible domain of the non-interference tool axis control point includes: determining the corresponding annular tool edge center point according to the contact point on the machining blade profile; determining the tool center point initial domain of the annular tool on a spherical surface with the edge center point as the center of the sphere and (R1-R2) as the radius; wherein R1 is the radius of the annular tool and R2 is the radius of the annular tool bottom edge; generating a first offset surface and a second offset surface according to the machining blade profile and the adjacent blade profile on both sides of the machining channel, respectively, and using the first offset surface and the second offset surface to generate a non-interference tool center point feasible domain surface in the tool center point initial domain; generating an auxiliary surface according to the first offset surface and the second offset surface, and projecting the tool center point feasible domain surface onto the auxiliary surface to obtain the non-interference tool axis control point feasible domain corresponding to the edge center point A; using the non-interference tool axis control point feasible domain corresponding to the edge center point A as the non-interference tool axis control point feasible domain of the contact point.

[0060] The embodiment of the present invention takes the blade back profile of a centrifugal impeller as an example to illustrate the specific implementation steps of the invention.

[0061] The initial conditions that the center point of the ring knife should satisfy are:

[0062] (1) The distance from any tool center point to the center point A of the annular blade is (R1-R2), where R1 is the radius of the annular blade and R2 is the radius of the annular blade bottom.

[0063] (2) In order to avoid the annular cutter and the processing blade S y In case of global interference, the annular cutter axis vector i should be ensured m The angle between the surface normal vector n at the contact point P is no greater than 90°. That is, it satisfies:

[0064] i m n ≥ 0 (1)

[0065] (3) Due to the unidirectional nature of the impeller channel when the annular cutter is machining the blade profile, the tool axis should always point to the blade tip and cut along the flow direction, that is, the tool axis vector i m The feed direction f should satisfy:

[0066] i m ·(f×n)≥0 (2)

[0067] In summary, the initial domain S of the ring knife center point o It is located on the 1 / 4 sphere S1 with the blade center point A as the sphere center and (R1-R2) as the radius, such as Figure 1 shown.

[0068] After obtaining the initial domain of the tool center point, calculate the feasible domain boundary of the tool center point without interference of the ring tool in this area. The specific steps are as follows:

[0069] First, take the center point A of the circular cutter as the origin and the normal vector direction n of the contact surface as X. L Axis, feed direction f is Z L axis, according to the right-hand theorem, determine Y L The direction of the axis is used to establish a local coordinate system. According to the spatial relationship, a point B is made on the straight line with the same direction as n. With AB as the diameter, a spherical surface S2 is made that can intersect with the spherical surface S1. The intersection line of the two spherical surfaces is X. L Arc curves with equal height in different directions, such as Figure 2 (a) As shown. Repeating this operation can obtain a series of arc curves with equal heights at the initial tool center point. (i=1,2,…N, where N is the total number of circular arc curves of equal height).

[0070] Then, on the straight line with point A as the origin and in the same direction as each arc curve, there exists The only corresponding point is O' 2,i , which satisfies the knife center point O2 like Figure 2 (b) As shown in Figure 2. From the knife center point O on the arc curve 2,i And the corresponding O' 2,i Construct a tool axis sequence (i.e. the straight line where the tool axis is located) to facilitate subsequent tool axis interference judgment.

[0071] Then, the first offset surface and the second offset surface are generated respectively according to the processed blade profiles and adjacent blade profiles on both sides of the processing channel. The specific method is:

[0072] The blade profile S y The radius of the annular cutter R1 is offset in the direction of the impeller processing channel, and a pipe surface with a radius of R1 is made at the blade tip line, and a quarter of it is taken to prevent the tool from colliding with the blade tip line, and the offset surface S' is obtained. y (i.e. the first offset surface). At the same time, the adjacent blade profile S d The radius of the circular cutter R1 is offset in the direction of the impeller processing channel, and a pipe surface with a radius of R1 is made at the blade tip line. A quarter of it is taken to obtain the offset surface S' d (ie the second biasing surface).

[0073] Then, the first offset surface and the second offset surface are used to generate a non-interference tool center point feasible domain surface in the tool center point initial domain. First, the tool center point initial domain is discretized into a number of contour arcs according to the above steps; the point O' corresponding to each contour arc is selected on the normal vector extension line of the contact point. 2,i , to satisfy Among them, A is the blade center point corresponding to the cutting contact point, O 2,i is a point on the contour arc; using point O' 2,iGenerate a number of tool axis lines with the points on the contour arcs; select points on the contour arcs corresponding to the tool axis lines that do not intersect the first offset surface and the second offset surface to form a tool center point feasible domain surface without interference.

[0074] Specifically, determine the contour arc O' 2,i After the projection, check whether it intersects with the blade offset surface. If there is a projection point on the blade offset surface, it means that the tool axis corresponding to this tool center point interferes with the blade. Through projection judgment, the boundary of the feasible domain S of all non-interfering tool center points can be obtained.

[0075] More specifically, taking the determination of the knife axis and the adjacent blades as an example, the contour arc Over O' 2,i Projection. If the projection curves are all on the offset surface S' d On, such as Figure 3 (a), then the knife center point on this contour arc line is 2,i All tool axes formed will interfere with adjacent blades during machining. If the projection point curve and the blade offset surface S' d The edge line l' d Intersect, such as Figure 3 (b) is located on the offset surface S' d The knife center point on the contour arc line corresponding to the projection curve of 2,i The tool axis formed will interfere with the adjacent blades during the machining process. d The points on the contour arc line without intersection are the non-interference knife center points of the circular knife. Over O' 2,i Projection and offset surface S' d No intersection, such as Figure 3 (c) shows that the knife center point on this contour arc line is 2,i The tool axis formed does not interfere with the adjacent blades during the machining process. Through the above judgment conditions, the feasible domain surface S of the tool center point without interference can be obtained.

[0076] Then, an auxiliary curved surface is generated according to the first offset surface and the second offset surface, specifically including: offsetting the edge line of the first offset surface radially outward along the impeller rotation axis to obtain a first offset curve; rotating the first offset curve around the impeller rotation axis to a predetermined position to obtain an auxiliary curved surface; wherein the predetermined position is the projection position of the edge line of the second offset surface on the rotation path of the first offset curve.

[0077] That is, take the bias surface S' y The edge line l' yThe curve l is obtained by offsetting the outer side of the hub by a normal distance Δ greater than half the depth of the machining channel. Δ , l Δ The auxiliary surface S is obtained by rotating around the impeller axis of rotation Δ Take the offset surface S' d The edge line is l' d , the curve l' d Projected onto the auxiliary surface as surface S Δ The other side boundary, S Δ As auxiliary surfaces solved by tool axis control points, such as Figure 4 As shown in this figure, the auxiliary surface S Δ The first biasing surface and the second biasing surface are nearly perpendicular.

[0078] The non-interference knife center area S is along the X L A series of non-interference tool center point trajectory lines are obtained by equi-height discretization in the direction. According to the above projection direction, the non-interference tool center point trajectory lines are projected onto the auxiliary surface S Δ The feasible domain of the non-interference knife axis control point of the circular knife corresponding to the cutting contact point is obtained. like Figure 5 shown.

[0079] Specifically, the normal vector direction of the contact point of the feasible domain surface of the tool center point is discretized to obtain a number of non-interference tool center point trajectory lines; the point O' corresponding to the contour arc where the non-interference tool center point trajectory line is located 2,i The projection point is used to project the point on the trajectory line of the non-interference tool center point onto the auxiliary surface.

[0080] Through the above method, we get a feasible domain of non-interference tool axis control points corresponding to a cutting contact point. Then, take a plane perpendicular to the impeller's rotation centerline to obtain the blade's equal height section line. For all the contact points (P i 1 ,P i 2 ,…,P i n ), the corresponding feasible domain of non-interference tool axis control points is like but As all the tangent points (P i 1 ,P i 2 ,…,P i n ) is the feasible domain of non-interference common tool axis control points.

[0081] like This means that during the machining process, one control line cannot control the annular cutter to complete the machining of the entire profile. At this time, you can select a smaller tool to regenerate the control line, or divide the blade into several areas along the radial direction and construct a tool axis control line for each area.

[0082] From the initial feasible domain surface set of non-interfering tool axis control points Take any point (T1, T2, ..., T m ), by (T1,T2,…,T m ) The space curve generated by fitting can be used as the tool axis control line for five-axis machining without interference of the circular tool. The initial tool axis control line L k like Figure 6 When constructing the tool axis control line, in order to obtain the optimal tool axis control line, the control line should be generated according to certain criteria. The optimization principle of the control line is: the cumulative arc length of the non-interference tool axis control line is the shortest and the curvature change is the smallest;

[0083] In order to take into account all the cutting rows on the blade, the middle cutting row on the blade should be optimized. First, calculate the middle cutting row l M All contact points The corresponding non-interference tool axis vector set And the A and C angle mapping decomposition is performed to obtain the plane domain set of machine tool kinematic variables (Φ1, Φ2, ..., Φ m ), and establish a coordinate system with the cumulative arc length s of the discrete cutting contact points of equal arc length on the cutting line and the machine tool kinematic variables A and C as coordinate axes, such as Figure 7 Then the feasible domain of each machine tool kinematic variable is discretized.

[0084] In order to satisfy the shortest cumulative arc length, first calculate the spline curve in M i (A i ,C i ,s i ), for all spline curves in the machine tool kinematic variable plane domain set (Φ1, Φ2, …, Φ m ) The curvature at the intersection point is summed and the curvature sum is guaranteed to be minimum. This can approximately achieve the minimum curvature change on the curve. The mathematical model is established as follows:

[0085]

[0086] In order to minimize the curvature change, the curve is connected to the machine tool kinematic variable plane domain set (Φ1, Φ2, ..., Φ m ) The arc length of adjacent intersection points is approximately replaced by the chord length. The following mathematical model is established:

[0087]

[0088] Among them, M i (A i ,C i ,s i )∈Φ i .

[0089] At the same time, satisfying f opt1 and f opt2 The spline curve can ensure that the kinematic variables of the machine tool change smoothly during the machining process, while avoiding interference between the tool axis and the parts, and the tool axis changes smoothly.

[0090] Finally, site analysis is required. This process includes:

[0091] Determine the blade center point of the tool according to the control point and the contact point; generate a spherical surface S with the blade center point as the sphere center and (R2-R1) as the radius A ; Generate a spherical surface S with the line connecting the control point and the blade center point as the diameter and the center of the line as the center B ; According to the spherical surface S A and spherical surface S B Determine the center point of the knife.

[0092] Among them, according to the spherical surface S A and spherical surface S B Determining the knife center point includes: according to the spherical surface S A and spherical surface S B Determine the space curve circle l O ; Determine the plane ∑ based on the control point, the tangent point and the surface normal vector at the tangent point; Based on the space curve circle l O Calculate the tool center point with plane∑.

[0093] Specifically, the control line can be discretized to obtain the control point corresponding to the cutting contact point. For a given control point on the knife axis control line, the tool posture is unique when the annular knife and the blade are in contact. Figure 8 As shown in the figure, it is the contact model of the annular cutter machining. The control point selected according to the relationship of the annular cutter machining surface is T. From the annular cutter structure model, it can be seen that the distance from the tool center point to the tool edge center point A is R2-R1, that is, there is a tool center point O2 located on the sphere S with A as the center and R2-R1 as the radius. A On, such as Fig. 9 shown.

[0094] The annular cutter shaft is perpendicular to the end face where the center line of the rounding of the bottom edge of the cutter (circular dotted line) is located. The knife center point is located at The sphere S is the diameter and the midpoint of TA is the center of the sphere B superior.

[0095] When the control point T, the contact point P and the surface normal vector n at the contact point P remain unchanged, the center point of the annular cutter is located on the spherical surface S at the same time. A and S B The knife center is located on the intersection of the two spheres. According to the spatial relationship, the intersection of the two spheres is the space curve circle l O .

[0096] When the control point T, the contact point P and the surface normal vector n at the contact point P remain unchanged, the unique plane Σ is determined by the point T, the point P and the vector n passing through the point P, and the tool center point is located on the plane. A and S B The intersection circle l O On the left, the knife center point that meets the conditions is the plane Σ and the curve circle l O The intersection of Fig.10 As shown in the figure, there are two points O2 and O3. The annular cutter with the tool center point O3 intersects with the surface, which does not satisfy the annular cutter and surface contact model. Therefore, when machining a free-form surface centrifugal impeller based on the control line annular cutter point milling, under the conditions of given control points, contact points and surface normal vectors at the contact points, there is a unique tool center point, which together with the control point constitutes the unique cutting posture of the tool.

[0097] In summary, the present invention proposes a control line-based five-axis machining tool axis control method for annular cutters, which solves the tool axis control problem in impeller machining. The present invention is used in the machining of a certain type of aero-engine centrifugal impeller, and a channel control line can be constructed, according to which the tool axis vector and tool center point at each cutting contact point can be obtained.

[0098] In addition, the changes of the machine tool rotation axis of the tool axis vector generated by the tool axis control method based on the control line and the general tool axis control method of a certain software with a fixed forward rake angle of 20° and a side slip angle of 3° are shown as follows Fig.11 As shown, Fig.11 (a) is the diagram of the variation of angle A. Fig.11 (b) is the C angle variation diagram. Fig.11 It can be seen that when the tool axis control method with fixed rake angle and side slip angle is adopted, the curvature of the change curve of the kinematic variable angle A of the machine tool is relatively large, and the rotation axis of the machine tool is prone to sudden changes during the processing, leaving defects on the processed surface. When the tool axis control method based on the control line is adopted, the change of the rotation axis of the machine tool is relatively stable, and the changes of its angle A and angle C are smoother than when the general algorithm is adopted. Therefore, the use of the tool axis control method based on the control line can effectively improve the processing quality. In addition, since the present invention uses an annular knife as a processing tool, the annular knife has the advantages of high efficiency and long tool life compared to a ball-end knife, and can also effectively improve the surface processing quality of the centrifugal impeller and reduce the processing cost to a certain extent.

[0099] The curved surface processed by the method of the present invention has the advantage of being smoother, and it also combines the advantages of high processing efficiency, good surface quality of parts processing and long tool life of annular cutters over ball-end cutters, so that one cutter can complete the processing of a blade surface before excessive wear. On the other hand, since the two rotating axes of the five-axis machining machine tool rotate evenly and slowly, the quality of the processed impeller is significantly improved.

[0100] The present invention also discloses a control line-based impeller annular cutter five-axis CNC machining tool axis control method, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the above-mentioned control line-based impeller annular cutter five-axis CNC machining tool axis control method is implemented.

[0101] The above-mentioned device can be a computing device such as a desktop computer, a notebook, a PDA, and a cloud server. The device may include but is not limited to a processor and a memory. Those skilled in the art will appreciate that the device may include more or fewer components, or a combination of certain components, or different components, for example, it may also include input and output devices, network access devices, etc.

[0102] The processor may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor may be a microprocessor or any conventional processor, etc.

[0103] In some embodiments, the memory may be an internal storage unit of the device, such as a hard disk or memory of the device. In other embodiments, the memory may also be an external storage device of the device, such as a plug-in hard disk, a smart memory card (Smart Media Card, SMC), a secure digital (Secure Digital, SD) card, a flash card (Flash Card), etc. equipped on the device. Further, the memory may also include both an internal storage unit of the device and an external storage device. The memory is used to store an operating system, an application program, a boot loader (BootLoader), data, and other programs, such as the program code of the computer program, etc. The memory may also be used to temporarily store data that has been output or is to be output.

[0104] It should be noted that the specific content of the above-mentioned device is based on the same concept as the embodiment of the method of the present invention. Its specific functions and technical effects can be found in the method embodiment part, and will not be repeated here.

Claims

1. A control line-based five-axis CNC machining tool axis control method for an impeller annular tool, characterized in that: The following steps are involved: According to the contact points on the processed blade surface, the corresponding feasible domain of the non-interference tool axis control points is determined; The intersection of the feasible domains of non-interference tool axis control points corresponding to the cutting contact points on each machining trajectory on the machining blade profile is calculated to obtain the feasible domain of non-interference common tool axis control points of each machining trajectory; Generating a non-interference tool axis control line in the feasible domain of the non-interference common tool axis control points; Calculate the corresponding tool center point according to each control point on the non-interference tool axis control line and the corresponding cutting contact point; Determine the corresponding feasible domain of non-interference tool axis control points including: Determine the corresponding annular blade center point according to the cutting contact point on the processed blade profile; Determine the initial domain of the center point of the annular knife on a spherical surface with the center point of the blade as the center of the sphere and (R1-R2) as the radius; wherein R1 is the radius of the annular knife and R2 is the radius of the bottom blade of the annular knife; Generating a first offset surface and a second offset surface respectively according to the machining blade profiles and adjacent blade profiles on both sides of the machining channel, and generating a tool center point feasible domain surface without interference in the tool center point initial domain by using the first offset surface and the second offset surface; Generate an auxiliary curved surface according to the first offset surface and the second offset surface, and project the feasible domain surface of the tool center point onto the auxiliary curved surface to obtain the feasible domain of the non-interference tool axis control point corresponding to the blade center point A; The feasible domain of the non-interference tool axis control points corresponding to the blade center point A is used as the feasible domain of the non-interference tool axis control points of the cutting contact point; The optimization principles for generating non-interference tool axis control lines in the feasible domain of non-interference common tool axis control points include: The non-interference tool axis control line has the shortest cumulative arc length and the smallest curvature change; Calculating the corresponding tool center point according to each control point on the non-interference tool axis control line and the corresponding cutting contact point includes: Determine the blade center point of the tool according to the control point and the cutting contact point; Generate a spherical surface S with the blade center as the sphere center and (R2-R1) as the radius A ; A spherical surface S is generated with the line connecting the control point and the blade center point as the diameter and the center point of the line as the sphere center. B ; According to the spherical surface S A and spherical surface S B Determine the knife center point; According to the spherical surface S A and spherical surface S B Determining the knife center point includes: According to the spherical surface S A and spherical surface S B Determine the space curve circle l O ; Determine the plane ∑ according to the control point, the tangent point and the surface normal vector at the tangent point; Based on the space curve circle l O Calculate the tool center point with plane∑.

2. The control line-based five-axis CNC machining tool axis control method for an impeller annular tool as claimed in claim 1, characterized in that: Generating a tool center point feasible domain surface without interference in the tool center point initial domain by using the first offset surface and the second offset surface comprises: Discretize the initial domain of the knife center point into a number of contour arcs; Select the point O2' corresponding to each contour arc on the normal vector extension line of the tangent point ,i , to satisfy Among them, A is the blade center point corresponding to the cutting contact point, O 2,i is a point in the contour arc; Using point O2' ,i Generate several tool axis lines with points on the contour arc; Points on the contour arc corresponding to the tool axis that does not intersect the first offset surface and the second offset surface are selected to form a tool center point feasible domain surface without interference.

3. A control line-based impeller annular cutter five-axis CNC machining tool axis control method as claimed in claim 1 or 2, characterized in that: Generating an auxiliary curved surface according to the first offset surface and the second offset surface comprises: The edge line of the first offset surface is offset radially outward along the impeller rotation axis to obtain a first offset curve; The first offset curve is rotated around the impeller rotation axis to a predetermined position to obtain the auxiliary curved surface; wherein the predetermined position is a projection position of an edge line of the second offset surface on the rotation path of the first offset curve.

4. The control line-based five-axis CNC machining tool axis control method for an impeller annular tool as claimed in claim 3, characterized in that: Projecting the feasible domain surface of the tool center point onto the auxiliary surface comprises: Discretize the feasible domain surface of the tool center point along the normal vector direction of the contact point to obtain a plurality of tool center point trajectory lines without interference; The point O2' corresponding to the contour arc where the non-interference tool center point trajectory line is located ,i is the projection point, and the point on the non-interference tool center point trajectory line is projected onto the auxiliary curved surface.

5. The control line-based five-axis CNC machining tool axis control method for an impeller annular tool as claimed in claim 1, characterized in that: Generating a first offset surface and a second offset surface respectively according to the processed blade profiles and adjacent blade profiles on both sides of the processing channel includes: Offsetting the machining blade profile in the direction of the machining channel by R1; The adjacent blade profiles are offset R1 in the direction of the machining channel.

6. A control line-based impeller annular cutter five-axis CNC machining tool axis control method, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the computer program, it implements the control line-based impeller annular tool five-axis CNC machining tool axis control method as described in any one of claims 1 to 5.

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