Multi-model-based non-ruled surface machining path interpolation method and machine tool

Abstract

The invention discloses a multi-model-based non-ruled surface machining path interpolation method, which comprises the following steps of: generating machining path model information based on a workpiece machining path line and a driving geometry for defining a cutter shaft direction; the processing path model information at least comprises cutter location point track model information, cutter shaft point track model information and cutter location point and cutter shaft point correlation function information; iterative interpolation of geometry and processing speed is carried out based on the processing path model information, firstly geometric interpolation is carried out to carry out dense decomposition interpolation steps on the processing path, data of all the interpolation steps are arranged into a list according to the processing sequence, then processing speed setting is carried out, and the processing speed is set based on an interpolation cutter location point after geometric interpolation; position information of each physical axis is calculated and stored according to the cutter axis vector inverse solution of the interpolation cutter location point; and arranging the interpolated and inversed information into a control command list to drive the machine tool equipment. The machining track of the non-ruled surface can be more accurately planned, the machining error is reduced, and the precision is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of machining, and in particular relates to a non-ruled surface machining path interpolation method based on multiple models and a machine tool. Background Art

[0002] For non-ruled surface machining, the tool axis vector and tool axis point are usually not defined by the machining surface. The tool axis vector needs to be defined by another method, such as: the tool axis vector is perpendicular to the upper surface of the workpiece, or the tool axis vector is parallel to a given vector, or the tool axis vector is defined by a driving geometry (point / line / surface). After the direction of the tool axis vector is determined, the tool axis point can be determined by the intersection of the tool axis vector and a certain geometric model (such as the lower surface of the workpiece during cutting, or the driving point / line / surface of milling), or by the length of the given tool axis vector. The mathematical model of the tool axis point can be obtained by fitting a series of tool axis points on the path. However, the prior art does not pass the mathematical model of the tool axis point trajectory to the interpolation module. Because the interpolator of the CNC system only has the mathematical model of the tool position point line segment (such as a circular arc line) and the information of the tool axis vector at the starting point and end point of the line segment, when the interpolator performs interpolation calculations on the line segment model, there is a lack of a reasonable method for interpolating the tool axis vector. An approximate method is to find a point on the tool axis vector at the start and end of the line segment, and then perform densification interpolation on the line connecting these two points. The number of interpolation points is consistent with the number of interpolation points of the tool position point trajectory segment, and the direction of the line connecting the two corresponding interpolation points is used as the tool axis vector after interpolation. The result is that it is difficult to obtain smooth tool axis motion control, which is prone to jitter, affecting the processing quality and efficiency. In order to make up for this defect, it is often necessary to discretize the processing path into point-to-point motion with very small intervals. The consequence is that the amount of processing program data is greatly increased, which brings difficulties to data transmission, program reading and modification. Moreover, even if it is discretized into point-to-point motion with very small intervals, jitter will occur due to frequent changes in the direction of motion. Summary of the invention

[0003] To solve the above problems, the purpose of the present invention is to provide a non-straight surface machining path interpolation method and machine tool based on multi-models. Interpolation is performed based on machining path model information including tool position point trajectory model information, tool axis point trajectory model information and tool position point and tool axis point correlation function information. The machining trajectory of the non-straight surface can be planned more accurately, machining errors and jitter can be reduced, and machining accuracy can be improved.

[0004] The technical solution provided by the present invention is: a non-ruled surface machining path interpolation method based on multiple models, comprising the following steps:

[0005] Step 1: Generate machining path model information based on the workpiece machining trajectory and the driving geometry defining the tool axis direction, wherein the machining path model information at least includes tool position point trajectory model information, tool axis point trajectory model information, and tool position point and tool axis point correlation function information;

[0006] Step 2: Iterative interpolation of geometry and machining speed is performed based on the machining path model information. First, geometric interpolation is performed to decompose the interpolation steps of the machining path. The data of all interpolation steps are arranged into a list according to the machining order. Then, the machining speed is set based on the interpolation tool position after geometric interpolation.

[0007] Step 3: Calculate the position information of each physical axis based on the inverse solution of the tool axis vector of the interpolated tool position and store it;

[0008] Step 4: Arrange the interpolated and inversely solved information into a control command list to drive the machine tool equipment.

[0009] Preferably, in step 1, generating the machining path model information based on the workpiece machining trajectory and the driving geometry defining the tool axis direction further includes:

[0010] When the machining of the workpiece is suitable for the tool axis vector to be perpendicular to the upper surface of the workpiece, the direction of the tool axis vector is determined by the normal vector of the upper surface of the workpiece, or, when the machining of the workpiece is suitable for the tool axis vector to be parallel to a given vector, the direction of the tool axis vector is determined by the given vector, and the tool axis point is determined by setting the limiting condition of the tool axis vector length. If a series of tool axis points can be expressed by simple geometric curves, these simple geometric curves are used as tool axis point trajectory models, otherwise the tool axis point trajectory model is expressed by fitting a series of tool axis points into spline curves. If the workpiece machining trajectory line can be expressed by simple geometric curves, these simple geometric curves are used as tool position point trajectory models, otherwise the workpiece machining trajectory line is discretized into multiple points, and the series of discrete points are fitted into a tool position point trajectory model, and the tool position point trajectory model and the tool axis point trajectory model are divided according to the arc length using a preset mathematical rule to obtain the tool position point and tool axis point correlation function information.

[0011] Preferably, in step 1, generating the machining path model information based on the workpiece machining trajectory and the driving geometry defining the tool axis direction further includes:

[0012] When the processing of the workpiece is suitable for taking a driving point to determine the direction of the tool axis vector, a point is selected in the adjacent space of the processing as the driving point, that is, the tool axis point, and a tool axis vector is generated between the tool position point. If the workpiece processing trajectory can be expressed by simple geometric curves, these simple geometric curves are used as the tool position point trajectory model. Otherwise, the workpiece processing trajectory is discretized into multiple points, and the series of discrete points are fitted into a spline curve as the tool position point trajectory model.

[0013] Preferably, in step 1, generating the machining path model information based on the workpiece machining trajectory and the driving geometry defining the tool axis direction further includes:

[0014] When the processing of the workpiece is suitable for taking curves as driving geometry, a driving curve is defined in the adjacent space of the processing. The driving curve is a tool axis point trajectory model. The tool axis points are divided according to the arc length using a preset mathematical rule on the driving curve. A plane is generated through each tool axis point and perpendicular to the driving curve. The intersection of the plane and the processing surface is the processing line. If the processing line can be expressed by a simple geometric curve, these simple geometric curves are used as the tool position point trajectory model. Otherwise, the processing line is discretized into multiple points, and this series of points are fitted into a spline curve to obtain the tool position point trajectory model. The tool position point trajectory model and the tool axis point trajectory model are divided according to the arc length using a preset mathematical rule to obtain the tool position point and tool axis point correlation function information.

[0015] Preferably, in step 1, generating the machining path model information based on the workpiece machining trajectory and the driving geometry defining the tool axis direction further includes:

[0016] When the machining of the workpiece is suitable for determining the direction of the tool axis vector perpendicular to a driving surface, a driving surface is defined in the adjacent space of the machining, and the driving surface matches the local shape of the workpiece. If the workpiece machining trajectory can be expressed by simple geometric curves, these simple geometric curves are used as tool position point trajectory models. Otherwise, the workpiece machining trajectory is discretized into multiple points, and the series of discrete points are fitted into a tool position point trajectory model. For each discretized point, the perpendicular point is found on the driving surface as the tool axis point. If a series of tool axis points can be expressed by simple geometric curves, these simple geometric curves are used as the tool axis point trajectory model. Otherwise, a series of tool axis points are fitted into a spline curve to obtain the tool axis point trajectory model, and the tool position point trajectory model and the tool axis point trajectory model are divided according to the arc length using a preset mathematical rule to obtain the tool position point and tool axis point correlation function information.

[0017] Preferably, the discretized tool position point and tool axis vector are offset by a tool head radius away from the workpiece machining surface, and then the offset series of tool position points are fitted as a spline curve as a tool position point trajectory model, and the offset series of tool axis points are fitted as a spline curve as a tool axis point trajectory model, and the tool position point trajectory model and the tool axis point trajectory model are divided according to the arc length using a preset mathematical rule to obtain the tool position point and tool axis point correlation function information.

[0018] Preferably, the method further comprises, during the interpolation process:

[0019] Insert the IO command into the buffer. In each interpolation cycle, the data that first enters the buffer is output from the interpolator to the inverse solver and IO module. The inverse solver calculates the position information of each physical axis from the interpolation tool position point and tool axis vector according to the machine tool inverse motion algorithm. If there is offset data input, the offset amount is superimposed, saved and output to the position control module of each axis.

[0020] Preferably, the method further comprises inserting a zero-length line segment at each line segment connection point, and optimizing the theoretical processing speed based on the tangential direction change of the zero-length line segment.

[0021] Preferably, the method further comprises inserting a transition arc in the list, and when applied to laser cutting processing, inserting a transition arc at a junction where a tangential direction change of the processing path exceeds a preset threshold.

[0022] Preferably, the method further comprises, when interpolation control is performed on a rigid tool, determining whether the tool is deformed by force during the machining process according to the initial tool axis vector and the workpiece model during the machining process, when the initial tool axis vector is deformed by force during the machining process, calculating the tool force deformation amount that needs to be reversely compensated according to the machining feature data of the non-straight surface collected in real time, obtaining the tool diameter, the force acting on the tool and the protruding length of the tool, and calculating the tool force deformation amount δ according to the tool force deformation amount formula;

[0023] The deformed initial tool axis vector is optimized according to the reversely compensated tool force deformation to effectively compensate for the error caused during the machining process and obtain the optimal tool axis vector;

[0024] The processing characteristic data of the rigid tool include three cutting elements, topographical characteristics of the processed surface, machine tool errors and data related to the processing technology.

[0025] Preferably, the method further comprises, when interpolation control is performed on the flexible tool, calculating the offset required for reverse compensation based on the prediction mathematical model and preset process parameters, and optimizing the offset initial tool axis vector according to the reverse compensation offset to effectively compensate for the error caused by the machining process:

[0026] The first prediction mathematical model is called to calculate the drag amount of the cutting workpiece according to the target parameter information of the current position point, and then calculate the first angle that needs to be swung along the cutting feed direction to perform reverse compensation;

[0027] Acquire a first component of the initial tool axis vector along the cutting feed direction, and perform a first optimization according to the first angle to obtain a second component result of the optimized tool axis vector along the cutting feed direction;

[0028] The second prediction mathematical model is called to calculate the lateral taper generated by cutting the workpiece according to the target parameter information of the current position point, and then calculate the second angle that needs to be swung in the vertical direction along the cutting feed direction to perform reverse compensation;

[0029] Obtaining a third component of the initial tool axis vector in a direction perpendicular to the cutting feed direction, and performing a second optimization according to the second angle to obtain a fourth component result of the optimized tool axis vector perpendicular to the cutting feed direction;

[0030] According to the values ​​of the second component and the fourth component, the final optimized tool axis vector is synthesized.

[0031] Based on the same concept, the present invention also provides a non-ruled surface machining path interpolation machine tool based on multiple models, comprising:

[0032] A path generation module generates machining path model information based on a workpiece machining trajectory line and a driving geometry defining a tool axis direction, wherein the machining path model information at least includes tool position point trajectory model information, tool axis point trajectory model information, and tool position point and tool axis point correlation function information;

[0033] Iterative interpolation module performs iterative interpolation of geometry and processing speed based on processing path model information. First, geometric interpolation is performed to decompose the interpolation steps of the processing path. The data of all interpolation steps are arranged into a list according to the processing sequence. Then, the processing speed is set based on the interpolation tool position after geometric interpolation.

[0034] The inverse solution operation module calculates and stores the position information of each physical axis based on the inverse solution of the tool axis vector of the interpolated tool position;

[0035] The command execution module arranges the interpolated and inverse solved information into a control command list to drive the machine tool equipment.

[0036] Due to the adoption of the above technical solution, the present invention has the following advantages and positive effects compared with the prior art:

[0037] The technical solution of the present invention uses a multi-model-based interpolation method to interpolate based on machining path model information including tool position point trajectory model information, tool axis point trajectory model information, and tool position point and tool axis point correlation function information. Compared with the prior art that only interpolates the tool position point trajectory, it can more accurately plan the machining trajectory and tool axis motion of non-straight surface machining, thereby improving motion smoothness and machining accuracy. The machining speed is set based on the interpolated tool position points after geometric interpolation, so that the machining motion is smoother and the quality of the machined surface is improved. Through iterative interpolation of geometry and machining speed, the machining path is optimized, unnecessary movement of the tool axis is reduced, and machining efficiency is improved. The setting of the machining speed takes into account the results of geometric interpolation, avoiding machining instability caused by speed mutations. The data of the interpolation steps are arranged in a list to ensure the continuity of the machining path, reduce pauses during machining, and improve machining efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] The specific embodiments of the present invention are further described in detail below with reference to the accompanying drawings, wherein:

[0039] Figure 1 A schematic diagram of an embodiment of a non-ruled surface machining path interpolation method based on multiple models of the present invention;

[0040] Figure 2 is a schematic diagram of an embodiment in which the tool axis vector is perpendicular to the upper surface of the workpiece;

[0041] Figure 3 It is a schematic diagram of an embodiment in which a knife axis vector is parallel to a given vector;

[0042] Figure 4 It is a schematic diagram of an embodiment in which the tool axis vector driving geometry is a driving point;

[0043] Figure 5 It is a schematic diagram of an embodiment in which the tool axis vector driving geometry is a straight line;

[0044] Figure 6 It is a schematic diagram of an embodiment in which the tool axis vector driving geometry is a cylindrical surface;

[0045] Figure 7 This is a schematic diagram of the tool position path and theoretical processing speed examples;

[0046] Figure 8 for Figure 7 Example of velocity distribution after example interpolation. DETAILED DESCRIPTION

[0047] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. The advantages and features of the present invention will become more apparent from the following description and claims. It should be noted that the drawings are all in a very simplified form and use non-precise ratios, which are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the present invention.

[0048] It should be noted that all directional indications in the embodiments of the present invention (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0049] The non-ruled surface processing of the present invention includes at least the following two situations: 1. The processing surface itself is not a ruled surface; 2. The processing surface is a ruled surface but the ruled surface is not used to define the tool axis vector. For example, when a cylinder is processed by a water jet, a three-dimensional model of the cylinder is not established during processing, but only the trajectory of the tool position point. This situation is also suitable for the solution of the present invention.

[0050] First embodiment

[0051] This embodiment provides a non-ruled surface machining path interpolation method based on multiple models, comprising the following steps:

[0052] Step 1: Generate machining path model information based on the workpiece machining trajectory and the driving geometry defining the tool axis direction, wherein the machining path model information at least includes tool position point trajectory model information, tool axis point trajectory model information, and tool position point and tool axis point correlation function information;

[0053] Step 2: Iterative interpolation of geometry and machining speed is performed based on the machining path model information. First, geometric interpolation is performed to decompose the interpolation steps of the machining path. The data of all interpolation steps are arranged into a list according to the machining order. Then, the machining speed is set based on the interpolation tool position after geometric interpolation.

[0054] Step 3: Calculate the position information of each physical axis based on the inverse solution of the tool axis vector of the interpolated tool position and store it;

[0055] Step 4: Arrange the interpolated and inversely solved information into a control command list to drive the machine tool equipment.

[0056] The technical solution of this embodiment uses a multi-model-based interpolation method to interpolate based on machining path model information including tool position point trajectory model information, tool axis point trajectory model information, and tool position point and tool axis point correlation function information. Compared with the prior art that only interpolates the tool position point trajectory, it can more accurately plan the machining trajectory and tool axis movement of non-straight surfaces, thereby improving movement smoothness and machining accuracy. The machining speed is set based on the interpolated tool position points after geometric interpolation, which makes the tool movement smoother and improves the quality of the machined surface. Through iterative interpolation of geometry and machining speed, the machining path is optimized, unnecessary movement of the tool axis is reduced, and machining efficiency is improved. The setting of the machining speed takes into account the results of geometric interpolation to avoid machining instability caused by speed mutations. The data of the interpolation steps are arranged in a list to facilitate data transmission and ensure machining continuity.

[0057] Preferably, see Figure 2 and Figure 3 In step 1, the processing path model information is generated based on the workpiece processing trajectory line and the driving geometry defining the tool axis direction, further comprising:

[0058] When the machining of the workpiece is suitable for the tool axis vector to be perpendicular to the upper surface of the workpiece, the direction of the tool axis vector is determined by the normal vector of the upper surface of the workpiece, or, when the machining of the workpiece is suitable for the tool axis vector to be parallel to a given vector, the direction of the tool axis vector is determined by the given vector, the tool axis point is determined by setting the limiting conditions of the tool axis vector length (the limiting conditions mentioned here include thickness or intersection with a certain surface, etc.), and the tool axis point trajectory model is expressed by fitting a series of tool axis points into spline curves. If this series of tool axis points can be expressed by simple geometric curves (such as straight lines, arcs, etc.), these simple geometric curves are used as tool axis point trajectory models. If the workpiece machining trajectory line can be expressed by simple geometric curves, these simple geometric curves are used as tool position point trajectory models, otherwise the workpiece machining trajectory line is discretized into multiple points, and the series of discrete points are fitted into a tool position point trajectory model, and the tool position point trajectory model and the tool axis point trajectory model are divided according to the arc length using a preset mathematical rule to obtain the tool position point and tool axis point correlation function information.

[0059] This embodiment expresses the tool axis point trajectory model through a spline curve, which can accurately control the tool axis vector. Specifically, NURBS or other spline curves can be used to make it perpendicular to the upper surface of the workpiece or parallel to a given vector. The continuity and smoothness of the spline curve ensure the continuity and smoothness of the tool axis movement, thereby improving the processing accuracy and stability. The tool position point and tool axis point correlation function information obtained by the equal division method ensures the smoothness of the tool movement, reduces the vibration and impact during the processing process, and improves the quality of the processed surface. Of course, any method in the prior art can also be used to obtain the tool position point and tool axis point correlation function, which should belong to the scope of protection of the general inventive concept of the present invention. For example, assuming that the arc lengths corresponding to the current point on the upper edge curve and the lower edge curve are S1 and S2 respectively, the mathematical law can be: (1) S2 = C*S1; (2) S2 = C*S1*S1. The former is a linear mathematical law, the special case is equal division, and the latter is a nonlinear mathematical law.

[0060] Preferably, see Figure 4 In step 1, the processing path model information is generated based on the workpiece processing trajectory line and the driving geometry defining the tool axis direction, further comprising:

[0061] When the machining of the workpiece is suitable for taking a driving point to determine the tool axis point, for example, when the workpiece machining trajectory is distributed in an approximate concave or convex shape, a point is selected in the machining adjacent space as the driving point, that is, the tool axis point, and a tool axis vector is generated between the tool position point, and the tool axis point trajectory model is degenerated into a point; if the workpiece machining trajectory can be expressed by a simple geometric curve, these simple geometric curves are used as the tool position point trajectory model, otherwise the workpiece machining trajectory is discretized into multiple points, and the series of discrete points are fitted into the tool position point trajectory model. The adjacent space represents the spatial range within a certain distance including the workpiece and the tool.

[0062] This embodiment selects a driving point to define the tool axis vector, which can conveniently control the direction of the tool to adapt it to the shape changes of the workpiece, ensure the smoothness of the tool movement, reduce vibration and impact during the processing, and improve the quality of the processed surface.

[0063] Preferably, see Figure 5 In step 1, the processing path model information is generated based on the workpiece processing trajectory line and the driving geometry defining the tool axis direction, further comprising:

[0064] When the machining of the workpiece is suitable for taking curves as driving geometry, for example, when the machining trajectory of the workpiece is distributed into a shape that is approximately around a curve (such as a straight line), a driving curve (such as a straight line) is defined in the adjacent space of the machining. The driving curve is a tool axis point trajectory model. The tool axis points are divided according to the arc length using a preset mathematical rule on the driving curve. A plane is generated through each tool axis point and perpendicular to the tangent direction of the driving curve. The intersection of the plane and the machining surface is the machining line. If the machining line can be expressed by a simple geometric curve, these simple geometric curves are used as the tool position point trajectory model. Otherwise, the machining line is discretized into multiple points, and this series of points is fitted into a spline curve to obtain the tool position point trajectory model, and the tool position point trajectory model and the tool axis point trajectory model are divided equally by arc length (one of the implementation methods) to obtain the tool position point and tool axis point correlation function information. The preset mathematical rule division method in this embodiment includes linear or nonlinear mathematical rules. For example, assuming that the arc lengths corresponding to the current point on the upper edge curve and the lower edge curve are S1 and S2 respectively, the mathematical rule can be: (1) S2 = C*S1; (2) S2 = C*S1*S1. The former is a linear mathematical rule, the special case of which is equal division, and the latter is a nonlinear mathematical rule.

[0065] This embodiment determines the tool axis vector by driving a curve (such as a straight line), which can conveniently control the direction of the tool to adapt it to the shape change of the workpiece and improve the processing accuracy. The processing line is discretized into multiple points and fitted into a spline curve. The continuity and smoothness of the spline curve ensure the continuity and smoothness of the tool axis movement, reduce vibration and impact during the processing, and improve the quality of the processed surface. The method of using a driving curve can conveniently control the direction of the tool, allowing the tool to process in a more appropriate posture compared to the driving point.

[0066] Preferably, see Figure 6 In step 1, the processing path model information is generated based on the workpiece processing trajectory line and the driving geometry defining the tool axis direction, further comprising:

[0067] When the machining of the workpiece is suitable for determining the direction of the tool axis vector perpendicular to a driving surface, for example, when the machining trajectory of the workpiece is distributed into a surface that is approximately tubular or spherical, a driving surface is defined in the adjacent space of the machining, and the driving surface matches the local shape of the workpiece. If the machining trajectory of the workpiece can be expressed by simple geometric curves, these simple geometric curves are used as tool position point trajectory models, otherwise the machining trajectory of the workpiece is discretized into multiple points, and a series of discrete points are fitted into a tool position point trajectory model. For each discrete point, the perpendicular foot point is found on the driving surface as the tool axis point, and then a series of tool axis points are fitted into a spline curve to obtain a tool axis point trajectory model. If this series of tool axis points can be expressed by simple geometric curves (such as straight lines, arcs, etc.), these simple geometric curves are used as tool axis point trajectory models, otherwise they are fitted into spline curves to express the tool axis point trajectory model. The tool position point trajectory model and the tool axis point trajectory model are divided according to the arc length using a preset mathematical rule to obtain the tool position point and tool axis point correlation function information.

[0068] This embodiment adopts a driving curved surface, see Figure 6 Taking the driven cylindrical surface as an example, if the workpiece machining trajectory can be expressed by simple geometric curves, these simple geometric curves are used as the tool position point trajectory model. Otherwise, the workpiece machining trajectory is discretized into multiple points, and the series of discrete points are fitted into a spline curve as the tool position point trajectory model. For each discrete tool position point, the perpendicular point is found on the driven cylindrical surface as the tool axis point. If a series of tool axis points can be expressed by simple geometric curves, these simple geometric curves are used as the tool axis point trajectory model. Otherwise, a series of tool axis points are fitted into a spline curve to obtain the tool axis point trajectory model, and the tool position point trajectory model and the tool axis point trajectory model are divided equally to obtain the tool position point and tool axis point correlation function information. When the workpiece machining trajectory is similar to the situation of cylindrical encirclement, the tool axis point trajectory model generated by the driven cylindrical surface ensures the continuity of the tool axis motion, avoids the machining instability caused by discontinuity, and thus improves the machining accuracy. The method of using the driven cylindrical surface allows the tool to process in a more reasonable posture, reduces the risk of collision interference, and improves machining efficiency. The preset mathematical rule division method in this embodiment includes linear or nonlinear mathematical relationships. For example, assuming that the arc lengths corresponding to the current points on the upper and lower curves are S1 and S2 respectively, the mathematical rule may be: (1) S2 = C*S1; (2) S2 = C*S1*S1. The former is a linear mathematical rule, with the special case of equal division, and the latter is a nonlinear mathematical rule.

[0069] In one embodiment, when interpolation control is performed for rigid tool processing (referring to processing with a small amount of tool deformation during the processing, such as milling), it is determined whether the tool is deformed by force during the processing of the initial tool axis vector and the workpiece model during the processing path generated and the initial tool axis vector is executed. When the initial tool axis vector is deformed by force during the processing of the processing path, the tool force deformation amount that needs to be reversely compensated is calculated based on the processing feature data of the non-straight surface collected in real time, the tool diameter, the force acting on the tool and the tool protruding length are obtained, and the tool force deformation amount δ is calculated according to the tool force deformation amount formula:

[0070]

[0071] Where D is the tool diameter, P is the force on the tool, L is the tool protrusion length, and E is a natural constant with a value of 2.718;

[0072] The deformed initial tool axis vector is optimized according to the reversely compensated tool force deformation to effectively compensate for the error caused during the machining process and obtain the optimal tool axis vector;

[0073] The processing characteristic data of the rigid tool include three cutting elements, topographical characteristics of the processed surface, machine tool errors and data related to the processing technology.

[0074] The tool clearance is calculated based on the three cutting elements, and the same method can be used for reverse compensation to reduce errors. This overcomes the defects of commonly used tool axis vector determination methods such as normal processing method, preset tool axis method, and interpolation method.

[0075] In one embodiment, when interpolation control is performed for flexible tool processing (referring to processing with large tool deformation during processing, such as water jet cutting, laser cutting, plasma arc cutting, etc.), the offset required for reverse compensation is calculated based on the prediction mathematical model and preset process parameters, and the initial tool axis vector after the offset is optimized according to the reverse compensation offset to effectively compensate for the error caused during the processing:

[0076] The first prediction mathematical model is called to calculate the drag amount of the cutting workpiece according to the target parameter information of the current position point, and then calculate the first angle that needs to be swung along the cutting feed direction to perform reverse compensation;

[0077] Acquire a first component of the initial tool axis vector along the cutting feed direction, and perform a first optimization according to the first angle to obtain a second component result of the optimized tool axis vector along the cutting feed direction;

[0078] The second prediction mathematical model is called to calculate the lateral taper generated by cutting the workpiece according to the target parameter information of the current position point, and then calculate the second angle that needs to be swung in the vertical direction along the cutting feed direction to perform reverse compensation;

[0079] Obtaining a third component of the initial tool axis vector in a direction perpendicular to the cutting feed direction, and performing a second optimization according to the second angle to obtain a fourth component result of the optimized tool axis vector perpendicular to the cutting feed direction;

[0080] According to the values ​​of the second component and the fourth component, the final optimized tool axis vector is synthesized.

[0081] Preferably, Figure 1 A schematic diagram of an implementation scheme of a non-ruled surface machining path interpolation method based on multiple models is given. The interpolation module can be placed outside the CAM software. If it is on the same computer, the interpolation module can obtain the above path information through shared memory. If it is not on the same computer, the machining path information can be expressed in a text file. If it is passed to the interpolation module via a text file, the interpolation module can first import the path information in the text file into an object list list of a C++ line segment class Entity. <entity>.

[0082] Preferably, the method further comprises inserting a zero-length line segment at each line segment connection point, and optimizing the theoretical processing speed based on the tangential direction change of the zero length.

[0083] By inserting a zero-length line segment at each line segment connection point, the theoretical processing speed is optimized based on the tangential direction change of the front and rear ends of the zero-length line segment, making the tool movement smoother, reducing vibration and impact during the processing, and improving the quality of the machined surface. The zero-length line segment can also realize the transition of the tool axis vector direction of adjacent line segments at the connection point, that is, although there is no movement of the tool position point in the zero-length line segment, there can be multi-axis movement caused by the change of the tool axis direction.

[0084] The interpolation module calls the process model to calculate the theoretical processing speed. The theoretical processing speed is calculated for each processing path and the endpoint of the path. This method requires that the processing path information contains information about changes in process parameters (such as thickness information, which is obtained by calculating the distance between the tool position point and the tool axis point or by the workpiece thickness parameter). The process model for calculating the processing speed uses the process parameters as independent variables and considers the curvature changes of the path curve (for example, the speed of the arc is different from the speed of the straight line, and the smaller the arc radius, the slower the speed). When calculating the speed of the path endpoint, the change in the path direction of the two adjacent line segments must also be considered.

[0085] The idle fast forward speed can be directly obtained from the user setting parameters. The idle fast forward speed and the calculated processing speed are stored in the list <entity>Preferably, the method further comprises inserting a transition arc in the list, and when applied to a high-speed and high-precision machining process such as laser cutting, inserting a transition arc at a junction where the tangential direction of the machining path changes by more than a preset threshold.

[0086] Specifically, first obtain the geometric data of the machining path, including the endpoint positions and connection methods of the line segments. Calculate the front and rear tangent directions of each line segment connection point in the machining path, and determine the magnitude of the change in the tangent direction. Set a threshold for tangent change to evaluate when a transition arc needs to be inserted to optimize the path. At the point where the tangent direction changes beyond the preset threshold, insert a transition arc into the list according to the preset radius and other parameters. <entity>Inserting transition arcs can effectively avoid jitter and reduced processing quality caused by sharp corners, which is particularly important in high-speed and high-precision processing such as laser cutting. At the same time, the addition of transition arcs can reduce machine tool vibration caused by rapid steering or zero-speed steering used to avoid jitter, thereby improving processing efficiency and quality. By inserting transition arcs at key connection points, the continuity and smoothness of the processing path are enhanced, sharp turns in the processing path are avoided, and the mechanical impact of the machine tool is reduced.

[0087] Preferably, the discretized tool position point and tool axis vector are offset by a tool head radius away from the workpiece processing surface, and then the offset series of tool position points are fitted into a spline curve as a tool position point trajectory model, and the offset series of tool axis points are fitted into a spline curve as a tool axis point trajectory model, and the tool position point trajectory model and the tool axis point trajectory model are divided according to the arc length using a preset mathematical rule to obtain the tool position point and tool axis point correlation function information. By offsetting outward by a tool head radius, the possible errors in the actual project are fully considered, thereby improving the final processing accuracy. This embodiment is suitable for cutting or milling processing. The preset mathematical rule division method in this embodiment includes linear or nonlinear mathematical rules. For example, assuming that the arc lengths corresponding to the current point on the upper edge curve and the lower edge curve are S1 and S2 respectively, the mathematical rule can be: (1) S2 = C*S1; (2) S2 = C*S1*S1. The former is a linear mathematical rule, with the special case of equal division, and the latter is a nonlinear mathematical rule.

[0088] Preferably, when performing geometric interpolation in step 2, the following steps are included:

[0089] Coarse interpolation is performed before fine interpolation. The coarse interpolation step includes determining the interpolation step length, determining the theoretical interpolation step length according to the interpolation accuracy, dividing each line segment in the list by the theoretical interpolation step length, and rounding to N, and dividing each line segment in the list by N to obtain the actual interpolation step length L;

[0090] The actual interpolation step length L is used to segment the line segment. The tool position point trajectory curve is first divided equally to obtain the interpolation tool position point.

[0091] The interpolation point on the tool axis point trajectory curve is found through the correlation function between the tool position point and the tool axis point, and the tool axis vector information corresponding to the interpolation tool position point is obtained;

[0092] Store the N line segments generated after interpolation into a sublist, and replace the line segments before interpolation with the data in this sublist;

[0093] The sublist is used to perform speed smoothing processing on the interpolated data, and the speed of the adjacent line segments is adjusted at the location where the speed suddenly changes.

[0094] Optionally, each line segment of the generated machining path can be expressed as a C++ class Entity, and the entire machining path can be represented by a C++ Entity list. <entity>To express, use the member variable m_dQuality of the Entity class to distinguish the processing line, cutting-in and cutting-out line, and fast-forward line;

[0095] For example, 1-5 represents level 5 processing quality, 9 represents cutting in and out, 10 represents fast forward in the idle stroke, and 13 represents the idle stroke transition line.

[0096] The processing path information is obtained by means of shared memory; or, the processing path information is expressed by means of a text file, wherein the processing path information text file contains general parameters of path segments, parameters of tool position point NURBS spline curves, and parameters of tool axis point NURBS spline curves.

[0097] If the interpolation module is placed inside the CAM software, the interpolation module can directly obtain the above path information. The example of class Entity is as follows:

[0098]

[0099]

[0100]

[0101] When performing geometric interpolation, the following methods can be used:

[0102] When the interpolation module cannot obtain the machining path model information by sharing memory with the CAM module, a text file can be used to pass the machining path model information to the interpolation module and restore it to a mathematical model in the interpolation module. The following example uses three lines in a text file (can also be combined into one line, three lines are for easy reading) to express the information of a machining path segment. The entire machining path is a combination of the information of the above single-segment machining path segments.

[0103] First row: m_nEntityNo, m_dQuality, m_dThickness, m_nOffset;

[0104] Second line: m_nEntityType_TCP,m_EPt_TCP_X,m_EPt_TCP_Y,m_EPt_TCP_Z,m_dRadius_TCP,m_dLength_TCP,{P; (X,Y,Z,R;X,Y,Z,R;...;X,Y,Z,R;X,Y,Z,R);(K;...K)};

[0105] The third line: m_nEntityType_Axis,m_EPt_Axis_X,m_EPt_Axis_Y,m_EPt_Axis_Z,m_dRadius_Axis,m_dLength_Axis,{P; (X,Y,Z,R;X,Y,Z,R;...;X,Y,Z,R;X,Y,Z,R);(K;...K)};

[0106] The parameters in the first line are the common parameters of the path segment, which can be defined by referring to the definition of the Entity class example above.

[0107] The parameters in the second line, except for the parameters in {}, can also refer to the definition of the Entity class example above. When m_nEntityType_TCP is 4, the parameters in {} are used instead. The parameters in {} represent the parameters of the tool point NURBS spline curve (P is the level of the NURBS spline curve, X / Y / Z in the first () are the control point coordinates, R is the weight of the control point, and the number of control points is at least equal to the number of levels; K in the second () is the node vector parameter, and the number of node vectors must be equal to the number of control points plus the level).

[0108] The parameters in the third line can also refer to the definition of the Entity class example above, except for the parameters in {}. The parameters in {} are only available when m_nEntityType_Axis is 4. The parameters in {} represent the parameters of the NURBS spline curve of the tool axis point.

[0109] Usually the first line of the text file should give the tool position point and tool axis point information at the origin of the machining path: m_StartPt_TCP_X, m_StartPt_TCP_Y, m_StartPt_TCP_Z, m_StartPt_Axis_X, m_StartPt_Axis_Y, m_StartPt_Axis_Z.

[0110] This embodiment provides a feasible implementation of geometric interpolation. The above geometric interpolation method can accurately plan the machining trajectory of non-ruled surfaces, reduce machining errors, and improve machining accuracy. The iterative optimization of geometric interpolation and speed smoothing simplifies the data processing process and improves the calculation speed. Specifically, when the upper computer performs geometric rough interpolation, the interpolation steps are:

[0111] a. Determine the interpolation step length. Determine the theoretical interpolation step length based on the rough interpolation accuracy. <entity>The arc length of each Entity in is divided by the theoretical interpolation step length, and rounded to N. The arc length of the Entity is divided by N to obtain the actual interpolation step length L.

[0112] b. Use the actual interpolation step length L to segment the Entity, first divide the tool position point (TCP) trajectory curve into equal parts to obtain the interpolation tool position point;

[0113] c. Find the interpolation point on the tool axis point trajectory curve through the tool position point and tool axis point correlation function, and obtain the tool axis vector information corresponding to the interpolation tool position point;

[0114] d. Store the N entities generated after interpolation into a sublist list <entity>, replace the Entity before interpolation with this list. The effect after the rough interpolation is completed is list <entity>The number of Entities increases, but the arc length of each Entity becomes shorter.

[0115] e. Sublist list <entity>The speed of the Entity in the interpolation inherits the theoretical processing speed of the Entity before interpolation. <entity>Perform speed smoothing processing, adjust the speed of the neighboring Entity where the speed changes suddenly, and achieve a smooth speed gradient (acceleration and deceleration) effect.

[0116] Subsequently, the host computer inserts the IO command. For a specific machining process, according to the attributes of the machining path, the corresponding IO control command is inserted at the appropriate interpolation tool position Entity, such as: for milling machining, insert the milling cutter selection command (m_nIO1), spindle on / off command (m_bIO2), cutting fluid on / off command (m_bIO3), etc.

[0117] Optionally, for a specific machining process, a process parameter interpolation step can be added to calculate process-related parameters at the interpolated tool position. If necessary, adjust the tool position and tool axis vector, or adjust the process parameters. For example: for milling, calculate the cutting force change and the compensation amount of the tool position, adjust the position of the tool position (m_SPt_TCP, m_EPt_TCP), and even the angle of the tool axis vector and the position of the tool axis point (m_SPt_Axis, m_EPt_Axis).

[0118] The upper computer module further generates and outputs the machining program text and imports it into the memory of the lower computer.

[0119] For Figure 1 In the embodiment shown, preferably, the method further comprises during the interpolation process:

[0120] Insert IO commands into the circular buffer. In each interpolation cycle, the data that first enters the circular buffer is output from the interpolator to the inverse solver and IO module. The inverse solver calculates the position information of each physical axis from the interpolated tool position and tool axis vector according to the machine tool inverse motion algorithm. If there is offset data input, the offset is superimposed, saved and output to the position control module of each axis.

[0121] This embodiment can accurately plan the machining trajectory of non-ruled surfaces through geometric interpolation and velocity interpolation. The upper computer adds a rough interpolation step to reduce the computational burden of the lower computer fine interpolation. Based on the results of geometric rough interpolation, velocity interpolation and iterative optimization can obtain a relatively continuous and smooth theoretical machining speed, which is conducive to improving machining efficiency and quality. For details, continue to refer to Figure 1 Taking the Codesys-based CNC system as an example, the code parser of the lower computer takes out N lines from the memory each time and converts these N lines of code into an ST language array similar to CNCData:ARRAY[0..99]OF ENTITY. This is an array named CNCData, and the data type is an array of ENTITY structure. 100 is the number of assumed member ENTITY. M code is converted to IO command member of ENTITY (such as bIO1). Spline curve data is converted to member structures SplineTCP and SplineAxis of ENTITY.

[0122] Here ENTITY is an ST language structure that collects the information converted from a line segment in the CNC code.

[0123] Input the CNCData array into an interpolator module, input the data converted by N lines of code (i.e. CNCData) into the poqDataIn port of the interpolator, input the interpolation period (assuming 1000 microseconds) into the dwIpoTime port, and input the acceleration / deceleration mode code (assuming 1, i.e. trapezoidal acceleration / deceleration) into the iVelMode port. The interpolator (Interpolator) restores the CNCData data converted by N lines of code into a machining path mathematical model (including the tool position point trajectory model, tool axis point trajectory model, and the tool position point and tool axis point correlation function), and then performs geometric interpolation. Decompose each machining path on the machining path into interpolation steps, and arrange the data of all interpolation steps into an array according to the machining order. The steps are:

[0124] a. Determine the interpolation step length. Calculate the interpolation step length based on the interpolation cycle (dwIpoTime) and the theoretical processing speed.

[0125] b. Calculate the number of interpolation cycles required for the interpolation step length based on the interpolation cycle and theoretical processing speed. For example, if the speed is slow, the interpolation step length requires 10 interpolation cycles, then within 10 interpolation cycles, the position data output by the interpolator will not change until the 10th interpolation cycle. If the speed is fast, an interpolation step length only requires 0.1 interpolation cycles, then within 1 interpolation cycle, the position data output by the interpolator will change by the equivalent of 10 interpolation steps, which may affect the processing accuracy. Therefore, for high-speed and high-precision application scenarios, a smaller interpolation cycle should be used.

[0126] c. Use the interpolation step length to segment the machining path tool position point (TCP) trajectory curve to obtain the interpolated tool position point. For zero-length line segments (joints), the arc angle of the tool axis direction change can also be segmented. The densification interpolation technology of the tool position point straight line, arc, and spline curve belongs to the prior art and is not within the scope of the present invention. The XYZ position information of the tool position point is stored in fXPos, fYPos, and fZPos.

[0127] d. Find the interpolation point on the tool axis point trajectory curve through the tool position point and tool axis point association function, and obtain the tool axis point coordinates and tool axis vector information of the corresponding interpolated tool position point. The association function of this embodiment only considers the case of equal division. For straight lines and circular arc curves, it is relatively simple to reconstruct the mathematical model of the trajectory curve. For NURBS spline curves, it is necessary to reconstruct the mathematical model of the NURBS spline curve from the data of the SPLINE structure, and then calculate the arc length of the tool axis point curve based on this mathematical model. The XYZ position information of the tool axis point is saved in fXPosAxis, fYPosAxis, and fZPosAxis.

[0128] e. Calculate the tool axis inclination (saved in fInclination) and azimuth (saved in fAzimuth) based on the tool position point and tool axis point information.

[0129] f. Store the interpolation point data into an ST language array similar to PathData:ARRAY[0..999]OF PATHSTEP. This is an array named PathData, and its data type is an array of PATHSTEP structures.

[0130] Here PATHSTEP is an ST language structure that collects the interpolation information of each interpolation point after interpolation.

[0131] The interpolator performs speed interpolation according to the acceleration and deceleration mode (such as trapezoidal acceleration and deceleration-1, trigonometric function acceleration and deceleration-2, exponential acceleration and deceleration-3, S-curve acceleration and deceleration-4, cubic polynomial acceleration and deceleration-5, etc.), takes the theoretical processing speed on the tool position point path as the target, takes the theoretical processing speed of the path endpoint as the starting point, and gradually adjusts the theoretical processing speed corresponding to each interpolated tool position point in the direction of the path midpoint in both directions to obtain a continuous and smooth processing speed. Figure 7 The figure shows an example of a tool position path with different theoretical machining speeds in different path segments. Figure 8 The figure shows an example of velocity distribution after interpolation. The simplest trapezoidal acceleration and deceleration is used here. The velocity smoothness can be improved by using S-curve acceleration and deceleration or other acceleration and deceleration models. Since acceleration and deceleration take time, the theoretical processing speed may not be achieved for shorter path segments. In the velocity interpolation step, the interpolation information is saved in (fVel).

[0132] The interpolator inserts IO commands according to the IO command member of ENTITY (such as ENTITY.bIO1) and saves them in, for example, PATHSTEP.bIO1.

[0133] Optionally, for a specific processing technology, a process parameter interpolation step can be added here (for the specific description of the flexible tool and rigid tool process, see the aforementioned embodiment section), and the process-related parameters are calculated at the interpolated tool position. If necessary, the tool position and tool axis vector are adjusted, or the process parameters are adjusted (for example, laser power is adjusted). In the case where the rough interpolation of the upper computer has already interpolated the process parameters, the process parameter interpolation step can be optionally omitted, so that the lower computer does not need to configure the process parameter model.

[0134] The PathData that completes the above interpolation steps is imported into a FIFO (first in, first out) circular buffer. In each interpolation cycle, the first PATHSTEP data that enters the circular buffer is output from the piSetPosition port of the interpolator to the pi input port of the inverse transformer and the IO module. The relevant operations of the circular buffer belong to the prior art and are not elaborated in detail in the present invention.

[0135] In each interpolation cycle, the inverse transformer (InverseTransformer) calculates the position information of each physical axis from the tool axis inclination (fInclination) and azimuth (fAzimuth) of the interpolated tool position point or other tool axis vector expressions according to the machine tool inverse motion algorithm. If there is offset data (dOffsetX, dOffsetY, dOffsetZ, dOffsetA, dOffsetB) input, the offset must be superimposed and saved in fXPos, fYPos, fZPos, fAPos, fBPos, and output to the fSetPosition input port of the position control module (ControlAxisByPos) of each axis.

[0136] In each interpolation cycle, the position control module (ControlAxisByPos) outputs the axis position information to the corresponding axis drive, such as X Drive. The communication technology between the lower computer and each axis drive and IO module (such as using EtherCAT bus communication) belongs to the prior art and is not specifically described in the present invention.

[0137] For some motion commands and IO commands that need to be generated in real time, such as the error compensation function, the lower computer needs to compare the position information fed back by the encoder of each axis with the error model, generate the command of the compensation motion step of the motion axis, and insert the command of the compensation motion step in real time during the execution of the original interpolation data. This belongs to the prior art and will not be elaborated in detail in the present invention.

[0138] Based on the same concept, the present invention also provides a non-ruled surface machining path interpolation machine tool based on multiple models, comprising:

[0139] A path generation module generates machining path model information based on a workpiece machining trajectory line and a driving geometry defining a tool axis direction, wherein the machining path model information at least includes tool position point trajectory model information, tool axis point trajectory model information, and tool position point and tool axis point correlation function information;

[0140] Iterative interpolation module performs iterative interpolation of geometry and processing speed based on processing path model information. First, geometric interpolation is performed to decompose the interpolation steps of the processing path. The data of all interpolation steps are arranged into a list according to the processing sequence. Then, the processing speed is set based on the interpolation tool position after geometric interpolation.

[0141] The inverse solution operation module calculates and stores the position information of each physical axis based on the inverse solution of the tool axis vector of the interpolated tool position;

[0142] The command execution module arranges the interpolated and inverse solved information into a control command list to drive the machine tool equipment.

[0143] Based on the same concept, the present invention also provides an electronic device, comprising: a memory, the memory being used to store a processing program; and a processor, the processor implementing any one of the above-mentioned multi-model-based non-ruled surface machining path interpolation methods when executing the processing program.

[0144] Based on the same concept, the present invention also provides a readable storage medium, on which a processing program is stored. When the processing program is executed by a processor, any one of the above-mentioned non-ruled surface machining path interpolation methods based on multiple models is implemented.

[0145] If the non-straight surface machining path interpolation method based on multiple models is implemented in the form of program instructions and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this embodiment is essentially or the part that contributes to the prior art or all or part of the technical solution can be embodied in the form of software. The computer software is stored in a storage medium, including several instructions for a computer device (which can be a personal computer, server, or network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present disclosure. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM), random access memory (RAM), disk or optical disk, etc., and other media that can store program codes.

[0146] Those skilled in the art can clearly understand that, for the sake of convenience and brevity in description, the identification content specifically executed by the above-described system and device can refer to the corresponding process in the aforementioned method embodiment.

[0147] The embodiments of the present invention are described in detail above in conjunction with the accompanying drawings, but the present invention is not limited to the above embodiments. Even if various changes are made to the present invention, if these changes fall within the scope of the claims of the present invention and their equivalents, they still fall within the protection scope of the present invention.< / entity> < / entity> < / entity> < / entity> < / entity> < / entity> < / entity> < / entity> < / entity>

Claims

1. A non-ruled surface machining path interpolation method based on multiple models, characterized in that: The steps include: Step 1: Generate machining path model information based on the workpiece machining trajectory and the driving geometry defining the tool axis direction, wherein the machining path model information at least includes tool position point trajectory model information, tool axis point trajectory model information, and tool position point and tool axis point correlation function information; Step 2: Iterative interpolation of geometry and machining speed is performed based on the machining path model information. First, geometric interpolation is performed to decompose the interpolation steps of the machining path. The data of all interpolation steps are arranged into a list according to the machining order. Then, the machining speed is set based on the interpolation tool position after geometric interpolation. Step 3: Calculate the position information of each physical axis based on the inverse solution of the tool axis vector of the interpolated tool position and store it; Step 4: Arrange the interpolated and inversely solved information into a control command list to drive the machine tool equipment.

2. The non-ruled surface machining path interpolation method based on multiple models according to claim 1, characterized in that: In step 1, the processing path model information is generated based on the workpiece processing trajectory line and the driving geometry defining the tool axis direction, further comprising: When the machining of the workpiece is suitable for the tool axis vector to be perpendicular to the upper surface of the workpiece, the direction of the tool axis vector is determined by the normal vector of the upper surface of the workpiece, or, when the machining of the workpiece is suitable for the tool axis vector to be parallel to a given vector, the direction of the tool axis vector is determined by the given vector, and the tool axis point is determined by setting the limiting condition of the tool axis vector length. If a series of tool axis points can be expressed by simple geometric curves, these simple geometric curves are used as tool axis point trajectory models, otherwise the tool axis point trajectory model is expressed by fitting a series of tool axis points into spline curves. If the workpiece machining trajectory line can be expressed by simple geometric curves, these simple geometric curves are used as tool position point trajectory models, otherwise the workpiece machining trajectory line is discretized into multiple points, and the series of discrete points are fitted into a tool position point trajectory model, and the tool position point trajectory model and the tool axis point trajectory model are divided according to the arc length using a preset mathematical rule to obtain the tool position point and tool axis point correlation function information.

3. The non-ruled surface machining path interpolation method based on multiple models according to claim 1, characterized in that: In step 1, the processing path model information is generated based on the workpiece processing trajectory line and the driving geometry defining the tool axis direction, further comprising: When the processing of the workpiece is suitable for taking a driving point to determine the direction of the tool axis vector, a point is selected in the adjacent space of the processing as the driving point, that is, the tool axis point, and a tool axis vector is generated between the tool position point. If the workpiece processing trajectory can be expressed by simple geometric curves, these simple geometric curves are used as the tool position point trajectory model. Otherwise, the workpiece processing trajectory is discretized into multiple points, and the series of discrete points are fitted into a spline curve as the tool position point trajectory model.

4. The non-ruled surface machining path interpolation method based on multiple models according to claim 1, characterized in that: In step 1, the processing path model information is generated based on the workpiece processing trajectory line and the driving geometry defining the tool axis direction, further comprising: When the processing of the workpiece is suitable for taking curves as driving geometry, a driving curve is defined in the adjacent space of the processing. The driving curve is a tool axis point trajectory model. The tool axis points are divided according to the arc length using a preset mathematical rule on the driving curve. A plane is generated through each tool axis point and perpendicular to the driving curve. The intersection of the plane and the processing surface is the processing line. If the processing line can be expressed by a simple geometric curve, these simple geometric curves are used as the tool position point trajectory model. Otherwise, the processing line is discretized into multiple points, and this series of points are fitted into a spline curve to obtain the tool position point trajectory model. The tool position point trajectory model and the tool axis point trajectory model are divided according to the arc length using a preset mathematical rule to obtain the tool position point and tool axis point correlation function information.

5. The non-ruled surface machining path interpolation method based on multiple models according to claim 1, characterized in that: In step 1, the processing path model information is generated based on the workpiece processing trajectory line and the driving geometry defining the tool axis direction, further comprising: When the machining of the workpiece is suitable for determining the direction of the tool axis vector perpendicular to a driving surface, a driving surface is defined in the adjacent space of the machining, and the driving surface matches the local shape of the workpiece. If the workpiece machining trajectory can be expressed by simple geometric curves, these simple geometric curves are used as tool position point trajectory models. Otherwise, the workpiece machining trajectory is discretized into multiple points, and the series of discrete points are fitted into a tool position point trajectory model. For each discretized point, the perpendicular point is found on the driving surface as the tool axis point. If a series of tool axis points can be expressed by simple geometric curves, these simple geometric curves are used as the tool axis point trajectory model. Otherwise, a series of tool axis points are fitted into a spline curve to obtain the tool axis point trajectory model, and the tool position point trajectory model and the tool axis point trajectory model are divided according to the arc length using a preset mathematical rule to obtain the tool position point and tool axis point correlation function information.

6. The non-ruled surface machining path interpolation method based on multiple models according to any one of claims 2 to 5, characterized in that: The discretized tool position point and tool axis vector are offset to the side away from the workpiece machining surface by a tool head radius, and then a series of tool position points after the offset are fitted into a spline curve as a tool position point trajectory model, and a series of tool axis points after the offset are fitted into a spline curve as a tool axis point trajectory model, and the tool position point trajectory model and the tool axis point trajectory model are divided according to the arc length using a preset mathematical rule to obtain the tool position point and tool axis point correlation function information.

7. The non-ruled surface machining path interpolation method based on multiple models according to claim 1, characterized in that: The method further comprises, during the interpolation process: Insert the IO command into the buffer. In each interpolation cycle, the data that first enters the buffer is output from the interpolator to the inverse solver and IO module. The inverse solver calculates the position information of each physical axis from the interpolation tool position point and tool axis vector according to the machine tool inverse motion algorithm. If there is offset data input, the offset amount is superimposed, saved and output to the position control module of each axis.

8. The non-ruled surface machining path interpolation method based on multiple models according to claim 1, characterized in that: The method further includes inserting a zero-length line segment at each line segment connection point, and optimizing the theoretical processing speed based on the tangential direction change of the zero-length line segment.

9. The non-ruled surface machining path interpolation method based on multiple models according to claim 8, characterized in that: The method further comprises inserting a transition arc in the list, and inserting the transition arc at a joint where the tangential direction of the machining path changes by more than a preset threshold.

10. The non-ruled surface machining path interpolation method based on multiple models according to claim 1, characterized in that: The method further includes, when interpolation control is performed on a rigid tool, determining whether the tool is deformed by force during the machining process according to the initial tool axis vector and the workpiece model during the machining process, when the initial tool axis vector is deformed by force during the machining process, calculating the tool force deformation amount that needs to be reversely compensated according to the machining feature data of the non-straight surface collected in real time, obtaining the tool diameter, the force acting on the tool and the protruding length of the tool, and calculating the tool force deformation amount according to the tool force deformation amount formula; The deformed initial tool axis vector is optimized according to the reversely compensated tool force deformation to effectively compensate for the error caused during the machining process and obtain the optimal tool axis vector; The processing characteristic data of the rigid tool include three cutting elements, topographical characteristics of the processed surface, machine tool errors and data related to the processing technology.

11. The non-ruled surface machining path interpolation method based on multiple models according to claim 1, characterized in that: The method further includes, when interpolation control is performed on the flexible tool, calculating the offset required for reverse compensation based on the prediction mathematical model and the preset process parameters, and optimizing the offset initial tool axis vector according to the reverse compensation offset to effectively compensate for the error caused during the machining process: The first prediction mathematical model is called to calculate the drag amount of the cutting workpiece according to the target parameter information of the current position point, and then calculate the first angle that needs to be swung along the cutting feed direction to perform reverse compensation; Acquire a first component of the initial tool axis vector along the cutting feed direction, and perform a first optimization according to the first angle to obtain a second component result of the optimized tool axis vector along the cutting feed direction; The second prediction mathematical model is called to calculate the lateral taper generated by cutting the workpiece according to the target parameter information of the current position point, and then calculate the second angle that needs to be swung in the vertical direction along the cutting feed direction to perform reverse compensation; Obtaining a third component of the initial tool axis vector in a direction perpendicular to the cutting feed direction, and performing a second optimization according to the second angle to obtain a fourth component result of the optimized tool axis vector perpendicular to the cutting feed direction; According to the values ​​of the second component and the fourth component, the final optimized tool axis vector is synthesized.

12. A non-ruled surface machining path interpolation machine tool based on multiple models, characterized in that: include: A path generation module generates machining path model information based on a workpiece machining trajectory line and a driving geometry defining a tool axis direction, wherein the machining path model information at least includes tool position point trajectory model information, tool axis point trajectory model information, and tool position point and tool axis point correlation function information; Iterative interpolation module performs iterative interpolation of geometry and processing speed based on processing path model information. First, geometric interpolation is performed to decompose the interpolation steps of the processing path. The data of all interpolation steps are arranged into a list according to the processing sequence. Then, the processing speed is set based on the interpolation tool position after geometric interpolation. The inverse solution operation module calculates and stores the position information of each physical axis based on the inverse solution of the tool axis vector of the interpolated tool position; The command execution module arranges the interpolated and inverse solved information into a control command list to drive the machine tool equipment.

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