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

Abstract

The present invention discloses a multi-model-based interpolation method for the machining path of non-developable surfaces. Based on the workpiece machining trajectory line and the driving geometry defining the cutter axis direction, machining path model information is generated. The machining path model information at least includes cutter location point trajectory model information, cutter axis point trajectory model information, and the associated function information between the cutter location points and the cutter axis points. Based on the machining path model information, iterative interpolation of geometry and machining speed is performed. First, geometric interpolation is carried out to densify and decompose the interpolation steps of the machining path, and the data of all interpolation steps are arranged into a list according to the machining order. Then, the machining speed is set, and the machining speed is set based on the interpolated cutter location points after geometric interpolation. The position information of each physical axis is calculated by inverse solution of the cutter axis vector of the interpolated cutter location points and stored. The information after interpolation and inverse solution is arranged into a control command list to drive the machine tool equipment. It can more accurately plan the machining trajectory of non-developable surfaces, reduce machining errors, and improve the accuracy.

Description

Technical Field

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

[0002] For non-developable surface machining, the tool axis vector and the tool axis point are usually not defined by the machining surface. The tool axis vector needs to be defined by other methods. For example, 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 geometric model (such as the lower surface of the workpiece during cutting, or the driving point / line / surface of milling machining), or can be determined by a given length of the tool axis vector. After fitting a series of tool axis points on the path, a mathematical model of the tool axis points can be obtained. However, the prior art does not transfer the mathematical model of the tool axis point trajectory to the interpolation module. Because the interpolator of the numerical control system only has the mathematical model of the tool point segment (such as an arc segment) and the information of the tool axis vector at the starting point and the ending point of the segment. When the interpolator performs interpolation calculation on the 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 starting point and the ending point of the segment respectively, and then perform densification interpolation on the line connecting these two points. The number of interpolation points is the same as that of the tool point trajectory segment. The direction of the line connecting the corresponding interpolation points of the two is used as the interpolated tool axis vector. The result is that it is difficult to obtain smooth tool axis motion control, and it is easy to generate jitter, affecting the machining quality and efficiency. To make up for this defect, it is often necessary to discretize the machining path into point-to-point motions with very small intervals, which results in a large increase in the amount of machining program data, bringing difficulties to data transmission, program reading and modification. Moreover, even if it is discretized into point-to-point motions with very small intervals, jitter will still be generated due to frequent changes in the motion direction. Summary of the Invention

[0003] To solve the above problems, the object of the present invention is to provide a non-developable surface machining path interpolation method and a machine tool based on multiple models. Interpolation is performed based on the machining path model information including tool point trajectory model information, tool axis point trajectory model information, and the correlation function information between tool points and tool axis points, which can more accurately plan the machining trajectory of non-developable surfaces, reduce machining errors and jitter, and improve machining accuracy.

[0004] The technical solution provided by the present invention is as follows: A non-developable surface machining path interpolation method based on multiple models, including the following steps:

[0005] Step 1: Generate machining path model information based on the workpiece machining trajectory line and the driving geometry that defines the cutter axis direction. The machining path model information at least includes cutter location point trajectory model information, cutter axis point trajectory model information, and the associated function information between cutter location points and cutter axis points.

[0006] Step 2: Perform iterative interpolation of geometry and machining speed based on the machining path model information. First, perform geometric interpolation to densify and decompose the interpolation steps of the machining path, arrange the data of all interpolation steps in a list according to the machining order, and then set the machining speed. Set the machining speed based on the interpolated cutter location points after geometric interpolation.

[0007] Step 3: Calculate the position information of each physical axis according to the inverse solution of the cutter axis vector of the interpolated cutter location points and store it.

[0008] Step 4: Arrange the information after interpolation and inverse solution 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 line and the driving geometry that defines the cutter axis direction further includes:

[0010] When the machining of the workpiece is suitable for the cutter axis vector to be perpendicular to the upper surface of the workpiece, determine the cutter axis vector direction through the normal vector of the upper surface of the workpiece. Or, when the machining of the workpiece is suitable for the cutter axis vector to be parallel to a given vector, determine the cutter axis vector direction through the given vector. Determine the cutter axis points by setting the limiting conditions of the cutter axis vector length. If a series of cutter axis points can be expressed by simple geometric curves, use these simple geometric curves as the cutter axis point trajectory model. Otherwise, express the cutter axis point trajectory model by fitting a series of cutter axis points into a spline curve. If the workpiece machining trajectory line can be expressed by simple geometric curves, use these simple geometric curves as the cutter location point trajectory model. Otherwise, discretize the workpiece machining trajectory line into multiple points and fit the discretized series of points into a cutter location point trajectory model. And obtain the associated function information between cutter location points and cutter axis points by dividing the cutter location point trajectory model and the cutter axis point trajectory model according to the arc length using a preset mathematical rule.

[0011] Preferably, in Step 1, generating the machining path model information based on the workpiece machining trajectory line and the driving geometry that defines the cutter axis direction further includes:

[0012] When the machining of the workpiece is suitable for the case of determining the cutter axis vector direction by a driving point, select a point as the driving point, that is, the cutter axis point, in the adjacent space of the machining to generate the cutter axis vector between the cutter axis point and the cutter location point. If the workpiece machining trajectory line can be expressed by simple geometric curves, use these simple geometric curves as the cutter location point trajectory model. Otherwise, discretize the workpiece machining trajectory line into multiple points and fit the discretized series of points into a spline curve as the cutter location point trajectory model.

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

[0014] When the machining of the workpiece is applicable to the case of taking a curve as the driving geometry, a driving curve is defined in the adjacent space of the machining. This driving curve is the cutter axis point trajectory model. The driving curve is divided by arc length according to a preset mathematical rule to obtain cutter axis points. Planes are generated through each cutter axis point and perpendicular to the driving curve. The intersection line of these planes and the machining surface is the machining line. If the machining line can be expressed by simple geometric curves, these simple geometric curves are used as the cutter location point trajectory model. Otherwise, the machining line is discretized into multiple points, and a series of these points are fitted into a spline curve to obtain the cutter location point trajectory model. The cutter location point trajectory model and the cutter axis point trajectory model are divided by arc length according to a preset mathematical rule to obtain the cutter location point and cutter axis point correlation function information.

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

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

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

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

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

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

[0021] Preferably, the method further includes inserting a transition arc in the list. When applied to laser cutting, a transition arc is inserted at the joint where the tangential direction change of the machining path exceeds a preset threshold.

[0022] Preferably, when performing interpolation control for a rigid tool, it is judged whether the initial tool axis vector is deformed by force during the generation of the machining path according to the initial tool axis vector and the workpiece model and during the machining process. When the initial tool axis vector is deformed by force during the machining path, the tool force deformation amount that needs to be compensated in the reverse direction is calculated based on the machining feature data of the non-developable surface collected in real time. The tool diameter, the force applied to the tool, and the tool protrusion length are obtained, and the tool force deformation amount δ is calculated according to the tool force deformation amount formula;

[0023] Optimize the deformed initial tool axis vector according to the tool force deformation amount compensated in the reverse direction to effectively compensate the error brought during the machining process, and obtain the optimal tool axis vector;

[0024] Among them, the machining feature data of the rigid tool includes the three cutting elements, the surface morphology characteristics of the machined surface, the machine tool error, and the data related to the machining process.

[0025] Preferably, when performing interpolation control for a flexible tool, the offset amount that needs to be compensated in the reverse direction is calculated based on the prediction mathematical model and the preset process parameters, and the offset initial tool axis vector is optimized according to the offset amount compensated in the reverse direction to effectively compensate the error brought during the machining process:

[0026] Call the first prediction mathematical model, calculate the trailing amount generated by cutting the workpiece according to the target parameter information of the current position point, and then calculate the first angle that needs to swing along the cutting feed direction for reverse compensation;

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

[0028] Call the second prediction mathematical model, 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 swing in the vertical direction along the cutting feed direction for reverse compensation;

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

[0030] Synthesize the final optimized tool axis vector according to the values of the second component and the fourth component.

[0031] Based on the same concept, the present invention also provides a multi-model-based non-developable surface machining path interpolation machine tool, including:

[0032] A path generation module that generates machining path model information based on the workpiece machining trajectory line and the driving geometry that defines the tool axis direction. 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 association function information;

[0033] An iterative interpolation module that performs iterative interpolation of geometry and machining speed based on the machining path model information. First, perform geometric interpolation to densify and decompose the interpolation steps of the machining path, arrange the data of all interpolation steps in a list according to the machining order, and then set the machining speed based on the interpolated tool position points after geometric interpolation;

[0034] An inverse solution operation module that inversely calculates and stores the position information of each physical axis according to the tool axis vector of the interpolated tool position point;

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

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

[0037] The technical solution of the present invention performs interpolation based on a multi-model interpolation method, based on machining path model information including cutter location point trajectory model information, cutter axis point trajectory model information, and the correlation function information between cutter location points and cutter axis points. Compared with the prior art that only performs interpolation for the cutter location point trajectory, it can more accurately plan the machining trajectory and cutter axis movement for non-developable surface machining, improve the motion smoothness and machining accuracy. The setting of the machining speed is based on the interpolated cutter location points after geometric interpolation, making the machining motion smoother and improving the quality of the machined surface. Through iterative interpolation of geometry and machining speed, the machining path is optimized, unnecessary movement of the cutter axis is reduced, and the machining efficiency is improved. The setting of the machining speed takes into account the result of geometric interpolation, avoiding machining instability caused by sudden speed changes. Arranging the interpolation step data into a list ensures the continuity of the machining path, reduces pauses during machining, and improves machining efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] The following further elaborates on the specific embodiments of the present invention with reference to the drawings, where:

[0039] Figure 1 is a schematic diagram of an embodiment of the multi-model non-developable surface machining path interpolation method of the present invention;

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

[0041] Figure 3 is a schematic diagram of an embodiment where the cutter axis vector is parallel to a given vector;

[0042] Figure 4 is a schematic diagram of an embodiment where the cutter axis vector drives the geometry as a driving point;

[0043] Figure 5 is a schematic diagram of an embodiment where the cutter axis vector drives the geometry as a straight line;

[0044] Figure 6 is a schematic diagram of an embodiment where the cutter axis vector drives the geometry as a cylindrical surface;

[0045] Figure 7 is a schematic diagram of an example of the cutter location point path and the theoretical machining speed;

[0046] Figure 8 is Figure 7 an example of the speed distribution after example interpolation. DETAILED DESCRIPTION OF THE EMBODIMENTS

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

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

[0049] The machining of non-developable surfaces of the present invention includes at least the following two cases: 1. The case where the machining surface itself is not a developable surface; 2. The case where the machining surface is a developable surface but the developable surface is not used to define the tool axis vector. For example, in the case of machining a cylinder by a water jet, during machining, a three-dimensional model of the cylinder is not established, but only the trajectory of the tool position points. This case is also suitable for adopting the solution of the present invention.

[0050] The First Embodiment

[0051] This embodiment provides a multi-model-based interpolation method for non-developable surface machining paths, including the following steps:

[0052] Step 1: Generate machining path model information based on the workpiece machining trajectory line and the driving geometry defining the tool axis direction. The machining path model information at least includes tool position point trajectory model information, tool axis point trajectory model information, and the associated function information between the tool position points and the tool axis points;

[0053] Step 2: Perform iterative interpolation of geometry and machining speed based on the machining path model information. First, perform geometric interpolation to densify and decompose the interpolation steps of the machining path, arrange the data of all interpolation steps in a list according to the machining order, and then set the machining speed, setting the machining speed based on the interpolated tool position points after geometric interpolation;

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

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

[0056] The technical solution of this embodiment performs interpolation based on a multi-model interpolation method and the machining path model information including tool point trajectory model information, tool axis point trajectory model information, and the correlation function information between tool points and tool axis points. Compared with the prior art that only interpolates the tool point trajectory, it can more accurately plan the machining trajectory of non-developable surfaces and the tool axis movement, improving the motion smoothness and machining accuracy. The machining speed is set based on the interpolated tool points after geometric interpolation, making the tool movement smoother and improving 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 the machining efficiency is improved. The setting of the machining speed takes into account the results of geometric interpolation, avoiding machining instability caused by sudden speed changes. The interpolation step data is arranged in a list for easy data transmission, ensuring machining continuity.

[0057] Preferably, referring to Figure 2 and Figure 3 , in step 1, further including generating the machining path model information based on the workpiece machining trajectory line and the driving geometry defining the tool axis direction:

[0058] When the machining of the workpiece is applicable to the tool axis vector being perpendicular to the upper surface of the workpiece, the tool axis vector direction is determined by the normal vector of the upper surface of the workpiece; or when the machining of the workpiece is applicable to the tool axis vector being parallel to a given vector, the tool axis vector direction is determined by the given vector. The tool axis points are determined by setting the limiting conditions for the length of the tool axis vector (the limiting conditions mentioned here include thickness or intersection points with a certain surface, etc.). The tool axis point trajectory model is expressed by fitting a series of tool axis points into a spline curve. 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 the tool axis point trajectory model. If the workpiece machining trajectory line can be expressed by simple geometric curves, these simple geometric curves are used as the tool point trajectory model; otherwise, the workpiece machining trajectory line is discretized into multiple points, and a series of the discretized points are fitted into the tool point trajectory model. The correlation function information between tool points and tool axis points is obtained by dividing the tool point trajectory model and the tool axis point trajectory model according to a preset mathematical rule by arc length.

[0059] In this embodiment, the tool axis point trajectory model is expressed by a spline curve, and the tool axis vector can be accurately controlled. 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 machining accuracy and stability. The information of the correlation function between the tool location points and the tool axis points obtained by the equal division method ensures the smoothness of the tool movement, reduces the vibration and impact during the machining process, and improves the quality of the machined surface. Of course, any method in the prior art can be used to obtain the correlation function between the tool location points and the tool axis points, which should fall within the scope protected by the general inventive concept of the present invention. For example, assuming that the arc lengths corresponding to the current points on the upper edge curve and the lower edge curve are S1 and S2 respectively, the mathematical rules can be: (1) S2 = C * S1; (2) S2 = C * S1 * S1. The former is a linear mathematical rule, and the special case is equal division, while the latter is a non-linear mathematical rule.

[0060] Preferably, referring to Figure 4 In step 1, the generation of the machining path model information based on the workpiece machining trajectory line and the driving geometry defining the tool axis direction further includes:

[0061] When the machining of the workpiece is suitable for the case where a driving point is used to determine the tool axis point, for example, when the workpiece machining trajectory line is distributed in an approximately concave or convex shape, a point is selected as the driving point, that is, the tool axis point, in the adjacent space of the machining to generate a tool axis vector between the tool axis point and the tool location point. The tool axis point trajectory model degenerates into a point; if the workpiece machining trajectory line can be expressed by simple geometric curves, these simple geometric curves are used as the tool location point trajectory model, otherwise the workpiece machining trajectory line is discretized into multiple points, and a series of discrete points are fitted into the tool location point trajectory model. The adjacent space refers to the space range within a certain distance that includes the workpiece and the tool.

[0062] In this embodiment, by selecting a driving point to define the tool axis vector, the direction of the tool can be conveniently controlled to adapt to the shape change of the workpiece, ensuring the smoothness of the tool movement, reducing the vibration and impact during the machining process, and improving the quality of the machined surface.

[0063] Preferably, referring to Figure 5 , in step 1, the generation of the machining path model information based on the workpiece machining trajectory line and the driving geometry defining the tool axis direction further includes:

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

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

[0066] Preferably, referring to Figure 6 , in step 1, further including generating the machining path model information based on the workpiece machining trajectory line and the driving geometry defining the tool axis direction:

[0067] When the machining of a workpiece is applicable to the case where the tool axis vector direction is determined perpendicular to a drive surface, for example, when the machining trajectory lines of the workpiece are distributed in an approximately tubular or spherical shape, a drive surface is defined in the adjacent space of the machining. The drive surface matches the local shape of the workpiece. If the machining trajectory lines of the workpiece can be expressed by simple geometric curves, these simple geometric curves are used as the tool point trajectory model. Otherwise, the machining trajectory lines of the workpiece are discretized into multiple points, and a series of the discretized points are fitted into a tool point trajectory model. For each discretized point, the foot point on the drive surface is found as the tool axis point, and then a series of tool axis points are fitted into a spline curve to obtain the 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 the tool axis point trajectory model. Otherwise, they are fitted into a spline curve to express the tool axis point trajectory model. And the tool point trajectory model and the tool axis point trajectory model are divided according to the arc length by a preset mathematical rule to obtain the correlation function information of the tool point and the tool axis point.

[0068] In this embodiment, by adopting a drive surface, see Figure 6 Taking the drive cylindrical surface as an example for illustration, if the machining trajectory lines of the workpiece can be expressed by simple geometric curves, these simple geometric curves are used as the tool point trajectory model. Otherwise, the machining trajectory lines of the workpiece are discretized into multiple points, and a series of the discretized points are fitted into a spline curve as the tool point trajectory model. For each tool point after discretization, the foot point on the drive cylindrical surface is found 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 further fitted into a spline curve to obtain the tool axis point trajectory model, and the tool point trajectory model and the tool axis point trajectory model are equally divided to obtain the correlation function information of the tool point and the tool axis point. When the machining trajectory lines of the workpiece form an approximately cylindrical surrounding situation, the tool axis point trajectory model generated by the drive cylindrical surface ensures the continuity of the tool axis movement, avoids machining instability caused by discontinuity, and thus improves the machining accuracy. The method of using the drive cylindrical surface allows the tool to machine with a more reasonable posture, reduces the risk of collision interference, and improves the machining efficiency. The preset mathematical rule division method in this embodiment includes linear or non-linear mathematical relationships. For example: Assume that the arc lengths corresponding to the current points 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, and the special case is equal division. The latter is a non-linear mathematical rule.

[0069] In one embodiment, when performing interpolation control for rigid tool machining (referring to machining with relatively small tool deformation during the machining process, such as milling), it is determined whether the initial tool axis vector undergoes force-induced deformation during the machining process when generating a machining path according to the initial tool axis vector and the workpiece model and executing the machining process. When the initial tool axis vector undergoes force-induced deformation during the machining path, the tool force-induced deformation amount that needs to be compensated backward is calculated based on the machining feature data of the non-developable surface collected in real time. The tool diameter, the force applied to the tool, and the tool protrusion length are obtained, and the tool force-induced deformation amount δ is calculated according to the tool force-induced deformation amount formula:

[0070]

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

[0072] The initial tool axis vector after deformation is optimized according to the tool force-induced deformation amount compensated backward to effectively compensate the errors brought during the machining process, and the optimal tool axis vector is obtained;

[0073] wherein, the machining feature data of the rigid tool includes the three cutting elements, the surface topography features of the machined surface, the machine tool errors, and the data related to the machining process.

[0074] The tool deflection amount is calculated according to the three cutting elements, and the same method can also be used for backward compensation to reduce errors. It overcomes the defects of common tool axis vector determination methods such as the normal machining method, the preset tool axis method, and the interpolation method.

[0075] In one embodiment, when performing interpolation control for flexible tool machining (referring to machining with relatively large tool deformation during the machining process, such as water jet cutting, laser cutting, plasma arc cutting, etc.), the offset amount that needs to be compensated backward is calculated based on the prediction mathematical model and the preset process parameters, and the initial tool axis vector after offset is optimized according to the offset amount compensated backward to effectively compensate the errors brought during the machining process:

[0076] The first prediction mathematical model is called, and the trailing amount generated by cutting the workpiece is calculated according to the target parameter information of the current position point, and then the first angle that needs to swing along the cutting feed direction is calculated for backward compensation;

[0077] The first component of the initial tool axis vector along the cutting feed direction is obtained, and the first optimization is performed according to the first angle to obtain the second component result of the optimized tool axis vector along the cutting feed direction;

[0078] Call the second prediction mathematical model, 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 swing in the vertical direction along the cutting feed direction for reverse compensation;

[0079] Obtain the third component of the initial tool axis vector in the vertical direction along the cutting feed direction, and perform a second optimization according to the second angle to obtain the result of the fourth component 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, synthesize the finally optimized tool axis vector.

[0081] Preferably, Figure 1 The figure shows a schematic diagram of an embodiment of a non-developable surface machining path interpolation method based on multiple models. The interpolation module can be placed outside the CAM software. If on the same computer, the interpolation module can obtain the above path information through shared memory. If not on the same computer, the machining path information can be expressed in a text file. If it is passed to the interpolation module through 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 includes inserting a zero-length line segment at each line segment connection point and optimizing the theoretical machining 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 and optimizing the theoretical machining speed based on the tangential direction change at the front and rear ends of the zero-length line segment, the tool movement becomes smoother, reducing vibration and impact during machining and improving the quality of the machined surface. This zero-length line segment can also achieve the transition of the tool axis vector direction of the adjacent line segments at the connection point. That is to say, although there is no movement of the tool point position on this zero-length line segment, there can be multi-axis movement generated by the change of the tool axis direction.

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

[0085] The rapid traverse speed can be directly obtained from the user-set parameters. The rapid traverse speed and the calculated machining speed are stored in list <entity>In the Entity.m_dSpeed member variable. Preferably, the method further includes inserting a transition arc in the list. When applied to high-speed and high-precision machining processes such as laser cutting, a transition arc is inserted at the joint 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 forward and backward tangential directions of each line segment connection point in the machining path and determine the magnitude of the tangential direction change. Set a threshold for tangential change to evaluate when a transition arc needs to be inserted to optimize the path. At the joint where the tangential direction changes by more than the preset threshold, insert a transition arc into the list according to the preset radius and other parameters. <entity>Among them. Inserting a transition arc can effectively avoid jitter and deterioration of machining quality caused by sharp corners, which is particularly crucial in high-speed and high-precision machining such as laser cutting. At the same time, the addition of the transition arc can reduce the machine tool vibration caused by rapid turning or the zero-speed turning adopted to avoid jitter, thereby improving the machining efficiency and quality. By inserting a transition arc at key connection points, the continuity and smoothness of the machining path are enhanced, sharp turns in the machining path are avoided, and the mechanical impact on the machine tool is reduced.

[0087] Preferably, the discrete tool position points and the tool axis vector are offset by one tool tip radius away from the workpiece machining surface side, and then a series of offset tool position points are fitted into a spline curve as the tool position point trajectory model, and a series of offset tool axis points are fitted into a spline curve as the tool axis point trajectory model. The tool position point and tool axis point correlation function information is obtained by dividing the tool position point trajectory model and the tool axis point trajectory model according to a preset mathematical law by arc length. By offsetting by one tool tip radius outward, possible errors in actual engineering are fully considered, thereby improving the final machining accuracy. This embodiment is applicable to the cases of cutting or milling machining. The way of dividing according to the preset mathematical law in this embodiment includes linear or non-linear mathematical laws. For example: assuming that the arc lengths corresponding to the current points 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, and the special case is equal division, and the latter is a non-linear mathematical law.

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

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

[0090] The line segment is segmented using the actual interpolation step size L. First, the tool position point trajectory curve is equally divided to obtain interpolation tool position points;

[0091] The interpolation points on the tool axis point trajectory curve are found through the tool position point and tool axis point correlation function to obtain the tool axis vector information corresponding to the interpolation tool position points;

[0092] The N segments generated after interpolation are stored in a sub-list, and the data in this sub-list replaces the line segments before interpolation;

[0093] The data after interpolation is smoothed in terms of speed through the sub-list, and the speeds of adjacent line segments are adjusted at the places where the speed changes suddenly.

[0094] Optionally, each line segment of the generated machining path is represented by a C++ class Entity, and the entire machining path can be represented by a list of C++ Entities <entity>It is expressed by using the member variable m_dQuality of the class Entity to distinguish the processing line, the cutting-in and cutting-out lines, and the rapid feed straight line.

[0095] For example, 1 - 5 represents the 5th level of processing quality, 9 represents the cutting-in and cutting-out, 10 represents the rapid feed during idle travel, and 13 represents the transition line during idle travel.

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

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

[0098]

[0099]

[0100]

[0101] When performing geometric interpolation, the following method can be adopted:

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

[0103] The first line: m_nEntityNo, m_dQuality, m_dThickness, m_nOffset;

[0104] The 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 general parameters of this path segment, and the definition in the example of the above Entity class can be referred to.

[0107] Except for the parameters within {}, the parameters in the second line can also refer to the definition in the example of the above Entity class. When m_nEntityType_TCP is 4, the parameters within {} are used to replace, and the parameters within {} represent the parameters of the tool point NURBS spline curve (P is the degree of the NURBS spline curve, the X / Y / Z within 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 degree number; the K within the second () is the knot vector parameter, and the number of knot vectors should be equal to the number of control points plus the degree).

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

[0109] Usually, the first line of the text file should give the tool 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 gives a feasible embodiment for geometric interpolation. Through the above geometric interpolation method, the machining trajectory of the non-developable surface can be accurately planned, the machining error can be reduced, and the machining accuracy can be improved. The iterative optimization of geometric interpolation and speed smoothing simplifies the data processing process and improves the calculation speed. Specifically, when performing geometric rough interpolation on the host computer, the interpolation steps are as follows:

[0111] a. Determine the interpolation step size. Determine the theoretical interpolation step size according to the rough interpolation accuracy, and put the list <entity>Divide the arc length of each Entity by the theoretical interpolation step length, and round down to N. Divide the arc length of the Entity by N to obtain the actual interpolation step length L;

[0112] b. Divide the Entity using the actual interpolation step length L. First, equally divide the trajectory curve of the tool center point (TCP) to obtain the interpolated tool center points;

[0113] c. Use the correlation function between the tool center point and the tool axis point to find the interpolation points on the trajectory curve of the tool axis point, and obtain the tool axis vector information corresponding to the interpolated tool center points;

[0114] d. Store the N Entities generated after interpolation into a sub-list list <entity>, replace this list with the Entity before interpolation. The effect after rough interpolation is list <entity>The number has increased, but the arc length of each Entity has become shorter.

[0115] e. Sub-list list <entity>The speed of the Entity in [ ] inherits the theoretical machining speed of the Entity before interpolation. After rough interpolation, the list after interpolation can be processed <entity>Perform speed smoothing processing, adjust the speeds of adjacent Entities at the locations of speed mutations, and achieve a smooth effect of gradual speed change (acceleration and deceleration).

[0116] Subsequently, the host computer inserts IO commands. For specific machining processes, according to the attributes of the machining path, corresponding IO control commands are inserted at appropriate interpolation tool point Entities. For example: for milling machining, insert milling cutter selection commands (m_nIO1), spindle on / off commands (m_bIO2), coolant on / off commands (m_bIO3), etc.

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

[0118] Furthermore, the host computer module generates and outputs the machining program text and imports it into the memory of the lower computer.

[0119] Regarding Figure 1 the illustrated embodiment, preferably, the method further includes during interpolation:

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

[0121] Through geometric interpolation and speed interpolation in this embodiment, the machining trajectory of non-developable surfaces can be accurately planned. Adding a rough interpolation step in the host computer can reduce the calculation burden of the fine interpolation in the lower computer. Based on the result of geometric rough interpolation, perform speed interpolation and iterative optimization to obtain a relatively continuous and smooth theoretical machining speed, which is beneficial to improving machining efficiency and quality. Specifically, continue to refer to Figure 1 , taking the Codesys-based numerical control system as an example, the code parser of the lower computer fetches 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 with the data type of ENTITY structure array, and 100 is the assumed number of ENTITY members. The M code is converted into the IO command member of ENTITY (such as bIO1). The data of the spline curve is converted into the member structures SplineTCP and SplineAxis of ENTITY.

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

[0123] Input the CNCData array into an interpolator module. The data converted from N lines of code (i.e., CNCData) is input to the poqDataIn port of the interpolator, the interpolation period (assumed to be 1000 microseconds) is input to the dwIpoTime port, and the acceleration / deceleration mode code (assumed to be 1, i.e., trapezoidal acceleration / deceleration) is input to the iVelMode port. The Interpolator restores the data CNCData converted from N lines of code to the machining path mathematical model (including the tool point trajectory model, the tool axis point trajectory model, and the correlation function between the tool point and the tool axis point), and then performs geometric interpolation. Each segment of the machining path on the machining path is densified and decomposed into interpolation steps, and the data of all interpolation steps are arranged into an array according to the machining order. The steps are as follows:

[0124] a. Determine the interpolation step size. Calculate the interpolation step size according to the interpolation period (dwIpoTime) and the theoretical machining speed.

[0125] b. Calculate the number of interpolation periods required for this interpolation step size according to the interpolation period and the theoretical machining speed. For example, if the speed is relatively slow and this interpolation step size requires 10 interpolation periods, then within 10 interpolation periods, the position data output by the interpolator will not change until the 10th interpolation period arrives, and then the position data output by the interpolator will change. If the speed is relatively fast and an interpolation step size only requires 0.1 interpolation period, then within 1 interpolation period, the position data output by the interpolator will change by an amount equivalent to 10 interpolation steps, which may affect the machining accuracy. Therefore, for high-speed and high-precision application scenarios, a smaller interpolation period should be adopted.

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

[0127] d. The interpolation points on the tool axis point trajectory curve are found through the tool point and tool axis point correlation function, and the tool axis point coordinates and tool axis vector information corresponding to the interpolated tool points are obtained. The correlation function in this embodiment only considers the evenly divided case. For the cases of straight lines and arc curves, the mathematical model for reconstructing the trajectory curve is relatively simple. For NURBS spline curves, it is necessary to reconstruct the NURBS spline curve mathematical model from the data of the SPLINE structure, and then calculate the arc length of the tool axis point curve according to this mathematical model. The XYZ position information of the tool axis points is stored in fXPosAxis, fYPosAxis, and fZPosAxis.

[0128] e. Calculate the tool axis inclination (stored in fInclination) and azimuth angle (stored in fAzimuth) according to the tool 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, which is an array named PathData with the data type of PATHSTEP structure.

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

[0131] The interpolator performs speed interpolation. According to the acceleration and deceleration modes (such as trapezoidal acceleration and deceleration - 1, trigonometric acceleration and deceleration - 2, exponential acceleration and deceleration - 3, S-shaped curve acceleration and deceleration - 4, cubic polynomial acceleration and deceleration - 5, etc.), with the theoretical machining speed on the tool point path as the target and the theoretical machining speed at the path end point as the starting point, the theoretical machining speed corresponding to each interpolated tool point is gradually adjusted in both directions towards the path midpoint direction to obtain a continuous and smooth machining speed. Figure 7 Shown is an example of a tool point path with different theoretical machining speeds in different path segments. Figure 8 Shown is an example of the speed distribution after interpolation. Here, the simplest trapezoidal acceleration and deceleration is used. Using an S-shaped curve acceleration and deceleration or other acceleration and deceleration models can improve its speed smoothness. Since acceleration and deceleration take time, for relatively short path segments, the theoretical machining speed may not be achieved. In this step of speed interpolation, the interpolation information is stored in (fVel).

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

[0133] Optionally, for a specific machining process, a step of interpolating process parameters can be added here (for the specific descriptions of the flexible tool and rigid tool processes, refer to the foregoing embodiment part). Calculate the process-related parameters of the interpolated tool position points. When necessary, adjust the tool position points and tool axis vectors, or adjust the process parameters (such as adjusting the laser power). If the process parameter interpolation has been done in the rough interpolation of the host computer, the step of process parameter interpolation can be omitted optionally, so that the slave computer can not be configured with a process parameter model.

[0134] Import the PathData that has completed the above interpolation steps into a FIFO (First In First Out) circular buffer. In each interpolation cycle, output the PATHSTEP data that first enters the circular buffer from the piSetPosition port of the interpolator to the pi input ports of the inverse solver (InverseTransformer) and the IO module (IO Module). The related operations of the circular buffer belong to the prior art and will not be specifically described in the present invention.

[0135] In each interpolation cycle, the inverse solver (InverseTransformer) calculates the position information of each physical axis according to the machine tool inverse kinematics algorithm from the tool axis inclination angle (fInclination) and azimuth angle (fAzimuth) of the interpolated tool position point or other expressions of the tool axis vector. If offset data (dOffsetX, dOffsetY, dOffsetZ, dOffsetA, dOffsetB) is input, the offset amount must be added 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 the X Drive. The communication technology between the slave computer and each axis drive and the IO module (such as using EtherCAT bus communication) belongs to the prior art and will not be 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 function of error compensation, the lower computer needs to compare the position information fed back by the encoders of each axis with the error model, generate commands for the compensation motion steps of the motion axes, and insert and execute the commands for the compensation motion steps in real time during the execution of the original interpolation data. This belongs to the prior art and will not be specifically described in the present invention.

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

[0139] A path generation module that generates machining path model information based on the workpiece machining trajectory line and the driving geometry defining the cutter axis direction. The machining path model information at least includes cutter location point trajectory model information, cutter axis point trajectory model information, and the correlation function information between the cutter location points and the cutter axis points;

[0140] An iterative interpolation module that performs iterative interpolation of geometry and machining speed based on the machining path model information. First, it performs geometric interpolation to densify and decompose the interpolation steps of the machining path, arranges the data of all interpolation steps into a list according to the machining order, and then sets the machining speed, setting the machining speed based on the interpolated cutter location points after geometric interpolation;

[0141] An inverse solution operation module that inversely calculates and stores the position information of each physical axis according to the cutter axis vector of the interpolated cutter location points;

[0142] A command execution module that arranges the information after interpolation and inverse solution 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, including: a memory for storing a processing program; a processor that, when executing the processing program, implements the non-developable surface machining path interpolation method based on multiple models described in any one of the above.

[0144] Based on the same concept, the present invention also provides a readable storage medium with a processing program stored thereon. When the processing program is executed by a processor, it implements the non-developable surface machining path interpolation method based on multiple models described in any one of the above.

[0145] If the non-ruled 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, in essence, or the part that contributes to the prior art, or all or part of this technical solution, can be embodied in the form of software. This computer software is stored in a storage medium and includes several instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods described in various embodiments of the present disclosure. The aforementioned storage medium includes: various media that can store program codes, such as USB flash drives, mobile hard disks, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical discs.

[0146] Those skilled in the art can clearly understand that for the sake of convenient and concise description, the specific identification content executed by the above-described system and device can refer to the corresponding process in the foregoing method embodiments.

[0147] The embodiments of the present invention have been 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, provided that these changes fall within the scope of the claims of the present invention and its equivalent technologies, they still fall within the protection scope of the present invention.< / entity> < / entity> < / entity> < / entity> < / entity> < / entity> < / entity> < / entity> < / entity>

Claims

1. A non-developable surface machining path interpolation method based on multiple models, characterized in that It includes the following steps: Step 1: Generate machining path model information based on the workpiece machining trajectory line and the driving geometry that defines the cutter axis direction. The machining path model information at least includes cutter location point trajectory model information, cutter axis point trajectory model information, and the associated function information between the cutter location point and the cutter axis point. Among them, the driving geometry includes the cases where the cutter axis vector is perpendicular to the upper surface of the workpiece, or when the machining of the workpiece is applicable to the cutter axis vector being parallel to a given vector, or a driving point is adopted to determine the cutter axis vector direction, or a curve is adopted as the driving geometry, or the cutter axis vector direction is determined perpendicular to a driving surface; Step 2: Perform iterative interpolation of geometry and machining speed based on the machining path model information. First, perform geometric interpolation to densify and decompose the interpolation steps of the machining path, arrange the data of all interpolation steps in a list according to the machining order, and then perform machining speed setting, setting the machining speed based on the interpolated cutter location points after geometric interpolation. Among them, the geometric rough interpolation steps are as follows: Determine the interpolation step length: Determine the theoretical interpolation step length according to the rough interpolation accuracy, divide the arc length of each line segment of the machining path by the theoretical interpolation step length and round up to N, and divide the arc length of the line segment by N to obtain the actual interpolation step length L; Use the actual interpolation step length L to divide the line segment. First, equally divide the cutter location point trajectory curve to obtain interpolated cutter location points; Find the interpolation points on the cutter axis point trajectory curve through the associated function between the cutter location point and the cutter axis point to obtain the cutter axis vector information corresponding to the interpolated cutter location points; Store the N sub-line segments generated after interpolation into a sub-line segment list, and replace the line segment before interpolation with this sub-line segment list; The speed of the sub-line segments in the sub-line segment list inherits the theoretical machining speed of the line segment before interpolation. After rough interpolation, perform speed smoothing processing on the sub-line segment list after interpolation is completed, and adjust the speeds of adjacent sub-line segments at the places where the speed changes suddenly to achieve a smooth effect of gradual speed change; Step 3: Calculate and store the position information of each physical axis according to the inverse solution of the cutter axis vector of the interpolated cutter location points; Step 4: Arrange the information after interpolation and inverse solution into a control command list to drive the machine tool equipment.

2. The multi-model based non-developable surface machining path interpolation method according to claim 1, wherein In Step 1, generating the machining path model information based on the workpiece machining trajectory line and the driving geometry that defines the cutter axis direction further includes: When the machining of the workpiece is applicable to the case where the tool axis vector is 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 applicable to the case where the tool axis vector is 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 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 the tool axis point trajectory model; otherwise, the tool axis point trajectory model is expressed by fitting a series of tool axis points into a spline curve. If the workpiece machining trajectory line can be expressed by simple geometric curves, these simple geometric curves are used as the tool location point trajectory model; otherwise, the workpiece machining trajectory line is discretized into multiple points, and a series of the discretized points are fitted into the tool location point trajectory model, and the tool location point and tool axis point correlation function information is obtained by dividing the tool location point trajectory model and the tool axis point trajectory model according to the arc length using a preset mathematical rule.

3. The multi-model based non-developable surface machining path interpolation method according to claim 1, characterized in that In step 1, further including generating machining path model information based on the workpiece machining trajectory line and the driving geometry defining the tool axis direction: When the machining of the workpiece is applicable to the case of determining the tool axis vector direction by using a driving point, a point is selected as the driving point, that is, the tool axis point, in the adjacent space of the machining, and a tool axis vector is generated between the tool axis point and the tool location point. If the workpiece machining trajectory line can be expressed by simple geometric curves, these simple geometric curves are used as the tool location point trajectory model; otherwise, the workpiece machining trajectory line is discretized into multiple points, and a series of the discretized points are fitted into a spline curve as the tool location point trajectory model.

4. The interpolation method for non-developable surface machining path based on multiple models according to claim 1, wherein In step 1, further including generating machining path model information based on the workpiece machining trajectory line and the driving geometry defining the tool axis direction: When the machining of the workpiece is applicable to the case of using a curve as the driving geometry, a driving curve is defined in the adjacent space of the machining. The driving curve is the tool axis point trajectory model. The tool axis points are obtained by dividing the driving curve according to the arc length using a preset mathematical rule. A plane is generated through each tool axis point and perpendicular to the driving curve. The intersection line of the plane and the machining surface is the machining line. If the machining line can be expressed by simple geometric curves, these simple geometric curves are used as the tool location point trajectory model; otherwise, the machining line is discretized into multiple points, and a series of the points are fitted into a spline curve to obtain the tool location point trajectory model, and the tool location point and tool axis point correlation function information is obtained by dividing the tool location point trajectory model and the tool axis point trajectory model according to the arc length using a preset mathematical rule.

5. The multi-model based non-developable surface machining path interpolation method according to claim 1, wherein In step 1, further including generating machining path model information based on the workpiece machining trajectory line and the driving geometry defining the tool axis direction: When the machining of a workpiece is applicable to the case where the cutter axis vector direction is determined perpendicular to a drive surface, a drive surface is defined in the adjacent space of the machining. The drive surface matches the local shape of the workpiece. If the machining trajectory line of the workpiece can be expressed by simple geometric curves, these simple geometric curves are used as the cutter location point trajectory model. Otherwise, the machining trajectory line of the workpiece is discretized into multiple points, and a series of discrete points are fitted into a cutter location point trajectory model. For each discrete point, the foot point on the drive surface is found as the cutter axis point. If a series of cutter axis points can be expressed by simple geometric curves, these simple geometric curves are used as the cutter axis point trajectory model. Otherwise, a series of cutter axis points are further fitted into a spline curve to obtain the cutter axis point trajectory model, and the cutter location point trajectory model and the cutter axis point trajectory model are divided according to the arc length by a preset mathematical rule to obtain the associated function information of the cutter location points and the cutter axis points.

6. The interpolation method for non-developable surface machining paths based on multiple models according to any one of claims 2-5, characterized in that The discrete cutter location points are offset by a cutter head radius in the direction away from the workpiece machining surface with the cutter axis vector, and then a series of offset cutter location points are fitted into a spline curve as the cutter location point trajectory model. A series of offset cutter axis points are fitted into a spline curve as the cutter axis point trajectory model, and the cutter location point trajectory model and the cutter axis point trajectory model are divided according to the arc length by a preset mathematical rule to obtain the associated function information of the cutter location points and the cutter axis points.

7. The multi-model based non-ruled surface machining path interpolation method according to claim 1, wherein The method further includes during the interpolation process: Insert an 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 the IO module. The inverse solver calculates the position information of each physical axis from the interpolated cutter location points and the cutter axis vector according to the machine tool inverse kinematics algorithm. If offset data is input, the offset amount is superimposed and saved and output to the position control module of each axis.

8. The multi-model-based non-developable surface machining path interpolation method according to claim 1, wherein The method further includes inserting a zero-length line segment at each line segment connection point to optimize the theoretical machining speed based on the tangential direction change of the zero-length line segment.

9. The multi-model-based non-developable surface machining path interpolation method according to claim 8, characterized in that, The method further includes inserting a transition arc in the list, and inserting a transition arc at the joint where the tangential direction change of the machining path exceeds a preset threshold.

10. The interpolation method for non-developable surface machining path based on multiple models according to claim 1, wherein, The method further includes, when performing interpolation control for a rigid tool, judging whether the initial cutter axis vector is deformed by force during the generation of the machining path and the execution of the machining process according to the initial cutter axis vector and the workpiece model. When the initial cutter axis vector is deformed by force during the machining path process, the cutter force deformation amount that needs to be compensated in the reverse direction is calculated based on the machining feature data of the non-developable surface collected in real time. The cutter diameter, the force applied to the cutter, and the cutter protrusion length are obtained, and the cutter force deformation amount is calculated according to the cutter force deformation amount formula; The deformed initial cutter axis vector is optimized according to the cutter force deformation amount compensated in the reverse direction to effectively compensate for the error brought during the machining process, and the optimal cutter axis vector is obtained; Among them, the machining feature data of the rigid tool includes the three cutting elements, the surface topography features of the machined surface, the machine tool error, and the data related to the machining process.

11. The interpolation method for non-developable surface machining path based on multiple models according to claim 1, wherein The method further includes that when interpolation control is performed on a flexible tool, an offset amount that needs to be compensated backward is calculated based on a prediction mathematical model and preset process parameters, and the initial tool axis vector after offset is optimized according to the offset amount compensated backward to effectively compensate for the errors brought during the machining process: Call the first prediction mathematical model, calculate the trailing amount generated by cutting the workpiece according to the target parameter information of the current position point, and then calculate the first angle that needs to swing along the cutting feed direction for backward compensation; Obtain the first component of the initial tool axis vector along the cutting feed direction, and perform the first optimization according to the first angle to obtain the second component result of the optimized tool axis vector along the cutting feed direction; Call the second prediction mathematical model, 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 swing along the direction perpendicular to the cutting feed direction for backward compensation; Obtain the third component of the initial tool axis vector along the direction perpendicular to the cutting feed direction, and perform the second optimization according to the second angle to obtain the fourth component result of the optimized tool axis vector perpendicular to the cutting feed direction; Synthesize the final optimized tool axis vector according to the values of the second component and the fourth component.

12. A non-developable surface machining path interpolation machine tool based on multiple models, characterized in that, It includes: A path generation module that generates machining path model information based on the workpiece machining trajectory line and the driving geometry that defines the tool axis direction. The machining path model information at least includes tool position point trajectory model information, tool axis point trajectory model information, and the correlation function information between tool position points and tool axis points; wherein, the driving geometry includes the cases where the tool axis vector is perpendicular to the upper surface of the workpiece, or when the machining of the workpiece is applicable to the tool axis vector being parallel to a given vector, or a driving point is adopted to determine the tool axis vector direction, or a curve is adopted as the driving geometry, or the tool axis vector direction is determined by being perpendicular to a driving surface; An iterative interpolation module that performs iterative interpolation of geometry and machining speed based on the machining path model information. First, perform geometric interpolation to densify and decompose the interpolation steps of the machining path, arrange the data of all interpolation steps in a list according to the machining sequence, and then perform machining speed setting, and set the machining speed based on the interpolated tool position points after geometric interpolation; where the geometric rough interpolation steps are: Determine the interpolation step length: Determine the theoretical interpolation step length according to the rough interpolation accuracy, divide the arc length of each line segment of the machining path by the theoretical interpolation step length and round up to N, and divide the arc length of the line segment by N to obtain the actual interpolation step length L; Use the actual interpolation step length L to divide the line segment, first equally divide the tool position point trajectory curve to obtain interpolated tool position points; Find the interpolation points on the tool axis point trajectory curve through the correlation function between tool position points and tool axis points, and obtain the tool axis vector information corresponding to the interpolated tool position points; Store the N sub-line segments generated after interpolation into a sub-line segment list, and replace the line segment before interpolation with this sub-line segment list; The speed of the sub-line segments in the sub-line segment list inherits the theoretical machining speed of the line segment before interpolation. After rough interpolation, perform speed smoothing processing on the sub-line segment list after interpolation is completed, and adjust the speeds of adjacent sub-line segments at the places where the speed changes suddenly to achieve the smooth effect of gradual speed change; Inverse solution operation module, inversely calculates the position information of each physical axis according to the tool axis vector of the interpolated tool point position and stores it; Command execution module, arranges the interpolated and inversely solved information into a control command list to drive the machine tool equipment.

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