Machining path interpolation numerical control system and machine tool based on multiple models

Abstract

The invention discloses a multi-model-based machining path interpolation numerical control system and a machine tool, and the system comprises a memory which obtains and stores machining path information and interpolated stepping information; the interpolator is used for reading the processing path information from the memory based on a selected interpolation strategy to carry out iterative interpolation of geometry and processing speed; wherein the interpolation strategy comprises the steps of performing interpolation on an upper computer, performing interpolation on a lower computer, performing coarse interpolation on the upper computer and performing fine interpolation on the lower computer; the inverse solver is used for inversely calculating the position information of each physical axis from the cutter location point position of the interpolation cutter location point and the cutter axis vector direction and storing the position information; and the driver is used for generating and outputting a motion control and / or IO control command to drive each shaft of the machine tool and matched equipment to work. Through the precise cutter location point track model, the cutter axis point track model and the cutter location point and cutter axis point correlation function, high-precision machining path control can be realized based on different interpolation strategies, so that the machining precision of a machined part is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of machining, and in particular relates to a machining path interpolation numerical control system and a machine tool based on multiple models. Background Art

[0002] The processing equipment in the machining field usually uses a CNC system. The processing program generated after the processing path and process planning in the CAM software is usually input into the CNC system in the format of G and M codes. The processing of complex mechanical parts is usually processed in the machining center through multi-axis processing such as turning, milling, and drilling. The engine impeller is a typical complex part. The impeller is widely used in the fields of energy, aviation, and navigation.

[0003] The five-axis machining program usually includes three-dimensional linear motion (G1) and circular motion (G2) of the tool position point. The linear motion or circular motion here refers to the motion trajectory of the tool position point, and the direction of the tool axis is expressed in the NC program in the following two ways. One way is to use the three components of the tool axis vector. The other way is to use the angles of the two rotation axes of the five-axis machine tool.

[0004] Before interpolation, NC programs expressed in rotational axis angles are generally converted into NC programs expressed in tool axis vectors using kinematic algorithms. After the NC program expressed in tool axis vectors is imported into the CNC system, the program must be interpolated in the interpolator of the CNC system. This is because the interpolator of the CNC system only has the mathematical model parameters of the tool position point segment (such as the radius and direction of a circular arc) and the information of the tool axis vectors at the start and end points of the segment. When the interpolator interpolates the segment model, there is a lack of a reasonable method to interpolate the tool axis vector. An approximate method is to find a point on the tool axis vector at the start and end points of the 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 interpolated tool axis vector. See Figure 5 Obviously, the shape of the workpiece cut in this way has a bow height error compared with the original conical surface, and for workpieces with higher precision requirements, the existing methods are difficult to meet the requirements. Summary of the invention

[0005] To solve the above problems, the purpose of the present invention is to provide a multi-model based machining path interpolation CNC system and machine tool, which can achieve high-precision machining path control based on different interpolation strategies through accurate tool position point trajectory model, tool axis point trajectory model and tool position point and tool axis point correlation function, thereby improving the machining accuracy of the workpiece.

[0006] The technical solution provided by the present invention is: a multi-model-based machining path interpolation numerical control system, comprising:

[0007] A memory, for acquiring and storing machining path information and interpolated step information, wherein the machining path information at least includes a tool position point trajectory model, a tool axis point trajectory model, and a tool position point and tool axis point correlation function; wherein the tool position point trajectory curve is correlated with an upper edge curve of a machining surface, and the tool axis point trajectory curve is correlated with a lower edge curve of a machining surface;

[0008] An interpolator, based on a selected interpolation strategy, reads the processing path information from the memory to perform iterative interpolation of geometry and processing speed, wherein the geometric interpolation decomposes each processing path on the processing path into interpolation steps according to a tool position point trajectory model, a tool axis point trajectory model, and a correlation function, arranges the data of all interpolation steps into a tool position point list according to a processing sequence, and then performs processing speed setting, and sets the processing speed based on the interpolated tool position point after geometric interpolation; wherein the interpolation strategy includes: interpolation on a host computer, interpolation on a slave computer, and coarse interpolation on a host computer and fine interpolation on a slave computer;

[0009] The inverse solver calculates and stores the position information of each physical axis from the tool position position of the interpolated tool position and the tool axis vector direction;

[0010] Driver generates and outputs motion control and / or IO control commands to drive the machine tool axes and supporting equipment.

[0011] Preferably, the interpolation strategy for interpolation performed on the host computer further includes executing the following steps on the host computer:

[0012] The interpolation module of the host computer obtains the processing path information, including the tool position point trajectory model, the tool axis point trajectory model and the tool position point and tool axis point correlation function, by sharing memory with the CAM module; or the modeling parameters of the above models are transferred from the CAM module to the interpolation module by data interaction, and then the modeling parameters are restored to the mathematical model; the above data interaction method can adopt the text file interaction method;

[0013] Determine the interpolation step length according to the interpolation cycle and / or the control accuracy and / or the theoretical processing speed;

[0014] The interpolation step length is used to segment the tool position point trajectory curve of the machining path line segment to obtain the interpolation tool position point;

[0015] Based on the correlation function between the tool position point and the tool axis point, the corresponding interpolation point on the tool axis point trajectory model is determined, and the interpolation tool axis point coordinates and tool axis vector information corresponding to the interpolation tool position point are obtained;

[0016] The interpolation tool position coordinates and tool axis vector data information are stored in an interpolation step list.

[0017] Preferably, the interpolation strategy for interpolation performed on the host computer further includes executing the following steps on the host computer:

[0018] Based on the acceleration limit and / or acceleration / deceleration model, the theoretical processing speed on the tool position path segment is taken as the maximum value, the theoretical processing speed at the end point of the path segment is taken as the starting point, and the theoretical processing speed corresponding to each interpolation tool position is gradually adjusted in the direction of the midpoint of the path segment in both directions in order to obtain a continuous and smooth processing speed;

[0019] And / or, adding a zero-length line segment at the endpoint of the path segment to set the theoretical processing speed of the path segment endpoint and the change of the tool axis vector; wherein the theoretical processing speed of the zero-length line segment is used for adjusting the above processing speed.

[0020] Preferably, the interpolation strategy for interpolation performed on the lower computer further includes executing the following steps on the lower computer:

[0021] The processing path segments are stored in the memory of the lower computer in the form of code, and the code contains the modeling parameter information of the processing path model. The code parser of the lower computer takes out N lines of code from the memory each time and converts them into a processing path segment array, and inputs the array into the interpolator module. At the same time, the interpolator module obtains the interpolation cycle and the acceleration and deceleration model;

[0022] The modeling parameter information of each machining path line segment code is restored into a tool position point trajectory mathematical model, a tool axis point trajectory mathematical model and a tool position point and tool axis point correlation function;

[0023] Determine the interpolation step length, segment the tool position point trajectory model of the machining path line segment according to the interpolation step length, and obtain the interpolation tool position point, wherein the arc angle of the tool axis direction change is segmented for the zero-length line segment;

[0024] The corresponding interpolation point on the tool axis point trajectory model is determined by the tool position point and tool axis point correlation function, the interpolation tool axis point coordinates and tool axis vector information are obtained, and the interpolation tool position point coordinates and tool axis vector data information are stored in an interpolation step list.

[0025] Preferably, the interpolation strategy for interpolation performed on the lower computer further includes executing the following steps on the lower computer:

[0026] Based on the acceleration and deceleration mode, the interpolator takes the theoretical processing speed on the tool position path segment as the maximum value, the theoretical processing speed at the end point of the path segment as the starting point, and aims to obtain a continuous and smooth processing speed. It gradually adjusts the theoretical processing speed corresponding to each interpolated tool position in both directions toward the midpoint of the path segment.

[0027] Preferably, the performing of coarse interpolation on the upper computer and fine interpolation on the lower computer further includes executing the following steps on the upper computer:

[0028] The coarse interpolation module of the host computer obtains the processing path information, including the tool position point trajectory model, the tool axis point trajectory model and the tool position point and tool axis point correlation function, by sharing memory with the CAM module; or the modeling parameters of the above models are transferred from the CAM module to the coarse interpolation module by data interaction, and then the modeling parameters are restored to the mathematical model; the above data interaction method can adopt the text file interaction method;

[0029] Determine the theoretical coarse interpolation step length according to the coarse interpolation accuracy, divide the arc length of each line segment in the machining path line segment list by the theoretical coarse interpolation step length, and round it to N, and divide the arc length of the line segment by N to obtain the actual coarse interpolation step length L;

[0030] The line segment is segmented using the actual interpolation step length L. The tool position trajectory model is first segmented equally to obtain the interpolation tool position.

[0031] Find the interpolation point on the tool axis point trajectory model 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;

[0032] The sublist of N segments generated after the rough interpolation of a single path segment is stored in the processing path segment list to replace the segment before interpolation; wherein the speed of each segment in the sublist is the same as the speed of the segment before interpolation;

[0033] And / or, where the speeds of adjacent line segments suddenly change and the movement directions suddenly change, the speeds of adjacent line segments are adjusted with the goal of speed smoothing.

[0034] Preferably, the performing of coarse interpolation on the upper computer and fine interpolation on the lower computer further includes executing the following steps on the lower computer:

[0035] The fine interpolation module of the lower computer obtains the list information of the machining path line segments after the rough interpolation, including the tool position point trajectory model, the tool axis point trajectory model and the tool position point and tool axis point correlation function information, by sharing memory with the rough interpolation module of the upper computer; or the modeling parameters of the above models are transferred from the rough interpolation module to the fine interpolation module by data interaction, and then the modeling parameters are restored to the mathematical model; the above data interaction method can adopt the text file interaction method;

[0036] Among them, if the modeling parameters of the above-mentioned model are transferred from the rough interpolation module to the fine interpolation module by means of data interaction, the processing path segments are stored in the memory of the lower computer in the form of code, and the code contains the modeling parameter information of the processing path model. The code parser of the lower computer takes out N lines of code from the memory each time and converts them into a processing path segment array, and inputs the array into the fine interpolator module. At the same time, the fine interpolator module obtains the interpolation cycle and the acceleration and deceleration model;

[0037] The modeling parameter information of each machining path line segment code is restored into a tool position point trajectory mathematical model, a tool axis point trajectory mathematical model and a tool position point and tool axis point correlation function;

[0038] Determine the fine interpolation step length, segment the tool position point trajectory model of the machining path according to the fine interpolation step length, and obtain the fine interpolation tool position point, wherein the arc angle of the tool axis direction change is segmented for the zero-length line segment;

[0039] The corresponding interpolation point on the tool axis point trajectory model is determined by the tool position point and tool axis point association function, the interpolation tool axis point coordinates and tool axis vector information are obtained, and the interpolation tool position point coordinates and tool axis vector data information are stored in an interpolation step array.

[0040] Preferably, the performing of coarse interpolation on the upper computer and fine interpolation on the lower computer further comprises:

[0041] The host computer performs the following steps:

[0042] The upper computer generates and outputs a processing program for the list data obtained after rough interpolation and sends it to the lower computer;

[0043] The lower computer performs the following steps:

[0044] Acquire the machining program to execute the fine interpolation operation, and perform speed smoothing processing after the fine interpolation;

[0045] The inverse solver is imported, and the inverse solver calculates the position information of each physical axis from the tool position coordinates of the interpolated tool position and the tool axis vector information according to the machine tool inverse motion algorithm.

[0046] Preferably, a zero-length line segment is added to the endpoint of the path segment to set the theoretical processing speed of the path segment endpoint and the change information of the tool axis vector; wherein the theoretical processing speed of the zero-length line segment is used for adjusting the above processing speed.

[0047] Preferably, when interpolation control is performed on a flexible tool, the offset required for reverse compensation 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 reverse compensation offset to effectively compensate for the error caused during the machining process:

[0048] 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;

[0049] 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;

[0050] 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;

[0051] 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;

[0052] According to the values ​​of the second component and the fourth component, the final optimized tool axis vector is synthesized.

[0053] Preferably, when interpolation control is performed on a rigid tool, it is determined whether the tool is deformed by force during the machining process when the machining path is generated according to the initial tool axis vector and the workpiece model and the initial tool axis vector is executed. When the initial tool axis vector is deformed by force during the machining path, the tool force deformation amount that needs to be reversely compensated is calculated based on the machining feature data 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 based on the tool force deformation amount formula;

[0054] 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;

[0055] 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.

[0056] Based on the same concept, the present invention also provides a machine tool, comprising any one of the above-mentioned multi-model-based machining path interpolation numerical control systems.

[0057] Due to the adoption of the above technical solution, the present invention has the following advantages and positive effects compared with the prior art:

[0058] 1. The present invention can achieve high-precision processing path control through accurate tool position point trajectory model, tool axis point trajectory model and tool position point and tool axis point correlation function, thereby improving the dimensional accuracy and surface quality of the workpiece. The interpolator can perform iterative interpolation of geometry and processing speed according to the processing path information, optimize the processing path, reduce unnecessary movement, and improve processing efficiency. The interpolator provides a variety of interpolation strategies, including interpolation in the host computer, interpolation in the slave computer, and rough interpolation in the host computer and fine interpolation in the slave computer. This can adapt to different processing requirements and machine tool performance, and improve the flexibility and applicability of processing. The processing speed is set based on the interpolated tool position point after geometric interpolation. The speed can be dynamically adjusted according to the geometric characteristics and process requirements of the processing path to optimize the processing process. The inverse solver can calculate the position information of each physical axis according to the position of the interpolated tool position point and the direction of the tool axis vector, ensuring the coordinated movement of each axis during the processing process and improving the processing accuracy.

[0059] 2. The present invention obtains accurate processing path information through shared memory or data interaction, ensuring accurate control of the tool position point and tool axis point. At the same time, the use of the tool position point and tool axis point correlation function ensures the coordinated movement of the two during the processing, which is particularly important for complex processing tasks. When the host computer interpolation strategy is adopted, the interpolation calculation can be implemented in the CAM module, so that the three-dimensional model of the workpiece can be obtained during interpolation, and nonlinear errors will not be caused due to the lack of the three-dimensional model of the workpiece during interpolation, and the correlation function can be easily obtained; the interpolation calculation can also be implemented outside the CAM module, but some model data, such as correlation functions, will be missing; due to the non-real-time nature of the interpolation calculation performed by the host computer, very complex calculations can be performed without worrying about the large amount of calculation being limited by the interpolation cycle. The foresight in traditional CNC is infinitely magnified. The N-line program foresight of traditional CNC can be extended to the entire processing program foresight, and reverse foresight can also be performed, which is conducive to ensuring the continuity and smooth changes of speed and acceleration as well as process parameters in a global range. The lower computer does not need to perform interpolation calculations (except for necessary real-time interpolation), and the algorithm module of the lower computer can be relatively simple, reducing hardware costs, improving reliability and stability, and even eliminating the need for an industrial computer. The interpolation algorithm is placed in the software of the upper computer, which is conducive to debugging, updating, upgrading, and maintenance.

[0060] 3. When the strategy of coarse interpolation of the upper computer and fine interpolation of the lower computer is adopted, the present invention can reduce the computational burden of fine interpolation of the lower computer by performing coarse interpolation on the upper computer. The coarse interpolation algorithm is placed in the software of the upper computer, which is easy to debug, update, upgrade and maintain. The amount of data after coarse interpolation is much smaller than the amount of data interpolated in the upper computer, and the stability requirements for data transmission between the upper and lower computers are low. For processing techniques that require real-time collection of multiple feedback signals and adjustment of processing data, the real-time performance is good and it is easier to achieve high speed and high precision requirements. The fine interpolation performed in the lower computer is based on the coarse interpolation results of the upper computer, and further refines the processing path. By restoring the modeling parameter information to a mathematical model and considering the relationship between the tool position point and the tool axis point in the fine interpolation, more accurate trajectory planning is achieved. The fine interpolation module of the lower computer can efficiently process the data after coarse interpolation, reduce data processing time, and improve processing efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0061] The specific embodiments of the present invention are further described in detail below with reference to the accompanying drawings, wherein:

[0062] Figure 1 It is a schematic diagram of the composition of the multi-model-based machining path interpolation numerical control system of the present invention;

[0063] Figure 2 It is a schematic diagram of the process of interpolation performed by the host computer of the present invention;

[0064] Figure 3 It is a schematic diagram of the process of interpolation performed on the lower computer of the present invention;

[0065] Figure 4 It is a flow chart of the present invention in which the upper computer performs rough interpolation and the lower computer performs fine interpolation;

[0066] Figure 5 A schematic diagram of bow height error generated by a two-axis swing head of a five-axis water jet cutting machine tool in the prior art;

[0067] Figure 6 This is an example of tool location path and theoretical processing speed;

[0068] Figure 7 An example of velocity distribution after interpolation. DETAILED DESCRIPTION

[0069] 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.

[0070] 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.

[0071] First embodiment

[0072] See also Figure 1 , this embodiment provides a multi-model-based machining path interpolation numerical control system, including:

[0073] A memory, for acquiring and storing machining path information and interpolated step information, wherein the machining path information at least includes a tool position point trajectory model, a tool axis point trajectory model, and a tool position point and tool axis point correlation function; wherein the tool position point trajectory curve is correlated with an upper edge curve of a machining surface, and the tool axis point trajectory curve is correlated with a lower edge curve of a machining surface;

[0074] An interpolator, based on a selected interpolation strategy, reads the processing path information from the memory to perform iterative interpolation of geometry and processing speed, wherein the geometric interpolation decomposes each processing path on the processing path into interpolation steps according to a tool position point trajectory model, a tool axis point trajectory model, and a correlation function, arranges the data of all interpolation steps into a tool position point list according to a processing sequence, and then performs processing speed setting, and sets the processing speed based on the interpolated tool position point after geometric interpolation; wherein the interpolation strategy includes: interpolation on a host computer, interpolation on a slave computer, and coarse interpolation on a host computer and fine interpolation on a slave computer;

[0075] The inverse solver calculates and stores the position information of each physical axis from the tool position position of the interpolated tool position and the tool axis vector direction;

[0076] Driver generates and outputs motion control and / or IO control commands to drive the machine tool axes and supporting equipment.

[0077] The technical solution of this embodiment can achieve high-precision processing path control through accurate tool position point trajectory model, tool axis point trajectory model and tool position point and tool axis point correlation function, thereby improving the dimensional accuracy and surface quality of the workpiece. The interpolator can perform iterative interpolation of geometry and processing speed according to the processing path information, optimize the processing path, reduce unnecessary movement, and improve processing efficiency. The interpolator provides a variety of interpolation strategies, including interpolation in the host computer, interpolation in the slave computer, and rough interpolation in the host computer and fine interpolation in the slave computer. This can adapt to different processing requirements and machine tool performance, and improve the flexibility and applicability of processing. The processing speed is set based on the interpolated tool position after geometric interpolation. The speed can be dynamically adjusted according to the geometric characteristics and process requirements of the processing path to optimize the processing process. The inverse solver can calculate the position information of each physical axis according to the position of the interpolated tool position point and the direction of the tool axis vector, ensuring the coordinated movement of each axis during the processing process and improving the processing accuracy.

[0078] Preferably, see Figure 2 The interpolation strategy for interpolation on the host computer further includes executing the following steps on the host computer:

[0079] The interpolation module of the host computer obtains the processing path information, including the tool position point trajectory model, the tool axis point trajectory model and the tool position point and tool axis point correlation function, by sharing memory with the CAM module; or the modeling parameters of the above models are transferred from the CAM module to the interpolation module by data interaction, and then the modeling parameters are restored to the mathematical model; the above data interaction method can adopt the text file interaction method;

[0080] Determine the interpolation step length according to the interpolation cycle and / or the control accuracy and / or the theoretical processing speed;

[0081] The interpolation step length is used to segment the tool position point trajectory curve of the machining path line segment to obtain the interpolation tool position point;

[0082] Based on the correlation function between the tool position point and the tool axis point, the corresponding interpolation point on the tool axis point trajectory model is determined, and the interpolation tool axis point coordinates and tool axis vector information corresponding to the interpolation tool position point are obtained;

[0083] The interpolation tool position coordinates and tool axis vector data information are stored in an interpolation step list.

[0084] The technical solution of this embodiment obtains accurate processing path information through shared memory or data interaction, ensuring accurate control of the tool position point and tool axis point. At the same time, the use of the tool position point and tool axis point correlation function ensures the coordinated movement of the two during the processing process, which is particularly important for complex processing tasks. When the host computer interpolation strategy is adopted, the interpolation calculation can be implemented in the CAM module, so that the three-dimensional model of the workpiece can be obtained during interpolation, and nonlinear errors will not be caused due to the lack of the three-dimensional model of the workpiece during interpolation, and the correlation function can be easily obtained; the interpolation calculation can also be implemented outside the CAM module, but some model data, such as correlation functions, will be missing; due to the non-real-time nature of the interpolation calculation performed by the host computer, very complex calculations can be performed without worrying about the large amount of calculation being limited by the interpolation cycle. The foresight in traditional CNC is infinitely magnified. The N-line program foresight of traditional CNC can be extended to the entire processing program foresight, and reverse foresight can also be used, which is conducive to ensuring the continuity and smooth changes of speed, acceleration and process parameters in a global range. The lower computer does not need to perform interpolation calculations (except for necessary real-time interpolation), and the algorithm module of the lower computer can be relatively simple, reducing hardware costs, improving reliability and stability, and even eliminating the need for an industrial computer. The interpolation algorithm is placed in the software of the upper computer, which is conducive to debugging, updating, upgrading, and maintenance.

[0085] In the CAM software, each line segment of the generated machining path can be expressed by a C++ class Entity, and the entire machining path can be represented by a C++ Entity object list. <entity>To express. The class member processing quality level m_dQuality can be used to distinguish processing lines, cut-in and cut-out lines, fast-forward lines, etc. For example, 1-5 is 5-level processing quality, 9 is cut-in and cut-out, 10 is idle fast-forward, and 13 is idle transition line. 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:

[0086]

[0087]

[0088]

[0089] Specifically, if the interpolation module is placed outside the CAM software but 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 processing path information can be expressed in a text file. For example, 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 processing path segment. The entire processing path is a combination of the information of the above single-segment processing path segments.

[0090] First row: m_nEntityNo,m_dQuality,m_dThickness,m_nOffset

[0091] Second line: m_nEntityType_TCP,m_EPt_TCP_X,m_EPt_TCP_Y,m_EPt_TCP_Z,m_dRadius_TCP,m_dLength_TCP,{P;K,X,Y,Z,R;K,X,Y,Z,R;K,X,Y,Z,R;...;K,X,Y,Z,R}

[0092] 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;K,X,Y,Z,R;K,X,Y,Z,R;K,X,Y,Z,R;...;K,X,Y,Z,R}

[0093] 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.

[0094] The parameters in the second line, except for the parameters in {}, can also refer to the definition of the Entity class example above. The parameters in {} are only available when m_nEntityType_TCP is 4. The parameters in {} represent the parameters of the tool point NURBS spline curve (P is the level of the NURBS spline curve, K is the node vector parameter, X / Y / Z is the control point coordinate, R is the weight of the control point, and the number of node vector parameters must be equal to the number of control points plus the level number P).

[0095] The parameters in the third line, except for the parameters in {}, can also refer to the definition of the Entity class example above. The parameters in {} are only available when m_nEntityType_Axis is 4. The parameters in {} represent the parameters of the tool axis point NURBS spline curve (P is the level of the NURBS spline curve, K is the node vector parameter, X / Y / Z is the control point coordinate, R is the weight of the control point, and the number of node vectors must be equal to the number of control points plus the level number P).

[0096] 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.

[0097] The above text file is passed to the interpolation module. The interpolation module must first import the path information in the text file into an Entity list list <entity>, and restore the modeling parameters representing straight lines, arcs, and spline curves into mathematical models.

[0098] Preferably, the interpolation strategy for interpolation performed on the host computer further includes executing the following steps on the host computer:

[0099] Based on the acceleration limit and / or acceleration / deceleration model, the theoretical processing speed on the tool position path segment is taken as the maximum value, the theoretical processing speed at the end point of the path segment is taken as the starting point, and the theoretical processing speed corresponding to each interpolation tool position is gradually adjusted in the direction of the midpoint of the path segment in both directions in order to obtain a continuous and smooth processing speed;

[0100] And / or, adding a zero-length line segment at the endpoint of the path segment to set the theoretical processing speed of the path segment endpoint and the change of the tool axis vector; wherein the theoretical processing speed of the zero-length line segment is used for adjusting the above processing speed.

[0101] The technical solution of this embodiment can achieve continuous and smooth changes in the processing speed by adjusting the theoretical processing speed based on the acceleration limit and acceleration and deceleration model, reduce the impact and vibration during the processing, and improve the processing quality. Smooth speed changes reduce the wear on machine tools and tools and extend the service life of the equipment. By gradually adjusting the theoretical processing speed in both directions to the midpoint of the path segment, the ideal processing speed can be reached more quickly, improving the processing efficiency. Adding a zero-length segment at the endpoint of the path segment to set the theoretical processing speed, the acceleration and deceleration near this point can be conveniently set during interpolation.

[0102] When performing speed interpolation, according to the acceleration limit of the machine, the acceleration limit of the specific process and the acceleration and deceleration model, the theoretical processing speed on the tool position path is taken as the target, and the theoretical processing speed at the path endpoint is taken as the starting point. The theoretical processing speed corresponding to each interpolated tool position is gradually adjusted in both directions toward the midpoint of the path to obtain a continuous and smooth processing speed.

[0103] The acceleration and deceleration models include trapezoidal acceleration and deceleration, trigonometric function acceleration and deceleration, exponential acceleration and deceleration, S-curve acceleration and deceleration, cubic polynomial acceleration and deceleration, etc. Figure 6 This is an example of a tool location path. Different path segments have different theoretical processing speeds. Figure 7 This is an example of speed distribution after interpolation. The simplest trapezoidal acceleration and deceleration is used here. The speed 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 speed interpolation step, the interpolation information is saved in (m_dSpeed, m_bDelay, m_sDelay), where the delay Delay is calculated from m_dSpeed ​​and m_dLength.

[0104] The present invention adopts an iterative interpolation method, that is, based on the introduced tool position point trajectory curve, tool axis point trajectory curve, tool position point and tool axis point correlation function, process parameter model, etc., geometric interpolation is first performed, and then the speed of the interpolated short line segment is set. Here, a speed model that can adapt to the continuous change of line segment characteristics (such as change of movement direction) is required. When performing the next step of process parameter interpolation, a group of process parameter models (cutting seam taper model, back drag model, etc.) that can adapt to the change of line segment characteristics and continuous change of speed are required. Therefore, in the entire processing program, the process parameters can change with the actual working conditions, and the interpolation accuracy is higher.

[0105] Preferably, before performing velocity interpolation, geometric interpolation is also performed to decompose each section of the processing path into interpolation steps, and the data of all interpolation steps are arranged into a list according to the processing sequence. The steps are:

[0106] a. Determine the interpolation step length. The first method: calculate the interpolation step length based on an interpolation cycle and the theoretical processing speed; the second method: determine the interpolation step length based on the control accuracy, and then calculate the number of interpolation cycles required for the interpolation step length based on the interpolation cycle and the theoretical processing speed; for zero-length line segments (joints), the interpolation step length refers to the arc angle of the tool axis direction change within an interpolation cycle or refers to the arc angle determined based on the arc angle control accuracy.

[0107] b. Use the interpolation step size to segment the machining path tool position point (TCP) trajectory curve to obtain the interpolated tool position point. For zero-length line segments (joint points), the arc angle of the tool axis direction change can also be segmented.

[0108] c. Use the tool position point and tool axis point association function to find the interpolation point on the tool axis point trajectory curve, and obtain the tool axis point coordinates and tool axis vector information of the corresponding interpolated tool position point. For the case of interpolation inside the CAM, the association function can be obtained from the Entity class. For the case of interpolation outside the CAM, the association function can be limited to the case of equal division. For zero-length tool position point segments (joints), no association function is required, and the tool axis point can be determined by the arc angle interpolation step, which is independent of the tool position point. For the case where the tool axis point trajectory curve degenerates into a point, no association function is required to determine the tool axis point.

[0109] d. Store the interpolation point data in the list list <pathstep>.

[0110] Here PathStep is a C++ class that collects the interpolation information of each interpolation point after interpolation. The following is an example of the PathStep class:

[0111]

[0112] In the geometric interpolation step, the interpolation information is mainly the geometric information of the interpolation point.

[0113] (m_StepPtS, m_StepPtE, m_nEntityNo, m_dOrientAngle, m_dLength, m_bDrive, m_sDrive).

[0114] For a specific processing technology, a process parameter interpolation step can be added to calculate the process-related parameters at the interpolation tool position. If necessary, adjust the tool position and tool axis vector, or adjust the process parameters. For example: for water jet cutting, according to the kerf taper model and the drag model and the speed of the current interpolation step, the current jet taper (m_dTE) and jet drag (m_dJL) are calculated at the interpolation tool position. If the tool axis inclination causes a substantial change in the actual cutting thickness, the cutting speed (m_dSpeed) also needs to be adjusted.

[0115] According to the machine tool inverse motion algorithm, the position information of each physical axis is calculated from the tool axis vector of the interpolated tool position. The position information can be incremental or absolute. The interpolation information is stored in (m_StepPtS, m_StepPtE, m_bDrive, m_sDrive).

[0116] In order to reduce the amount of data, a data compression step can be added here. In the interpolation step data list generated in the above steps, adjacent interpolation steps with the same data are found and these interpolation steps are merged into an interpolation step that is repeated multiple times. The repetition information is saved in (m_bRepeat, m_sRepeat).

[0117] The above interpolation information (m_bIO, m_bDrive, m_bDelay, m_bRepeat) is listed as a command control word list. The command control word consists of 4 WORDs, 64 bits, or 8 bytes. The format is as follows:

[0118] "IO|Drive|Delay|Repeat"

[0119] The "IO" field occupies a 16-bit WORD

[0120] The "Drive" field occupies a 16-bit WORD

[0121] The "Delay" field occupies a 16-bit WORD

[0122] The "Repeat" field occupies a 16-bit WORD.

[0123] In the case of interpolation on the host computer, send the above command control word list to the lower computer of the CNC system. Because the amount of data after interpolation is relatively large, the method of sending data in batches can be used to send data to the lower computer. The function of the lower computer is to cache the interpolation data and execute the motion commands and IO commands of each physical axis in the data in sequence. If interpolation is performed on the lower computer, the interpolation information is directly stored in the memory of the lower computer.

[0124] For some motion commands and IO commands that need to be generated in real time, such as the cutting head height following function in water jet cutting, the lower computer needs to generate the compensation motion step command of the motion axis based on the height information fed back by the height following sensor, and insert the compensation motion step command in real time during the execution of the original interpolation data.

[0125] Second embodiment

[0126] In some solutions of the first embodiment, the specific method of the strategy for interpolation in the host computer is specifically disclosed. The technical solution provided in this embodiment is described in detail in Figure 3 The interpolation strategy for interpolation in the lower computer further includes executing the following steps in the lower computer:

[0127] The processing path segments are stored in the memory of the lower computer in the form of code, and the code contains the modeling parameter information of the processing path model. The code parser of the lower computer takes out N lines of code from the memory each time and converts them into a processing path segment array, and inputs the array into the interpolator module. At the same time, the interpolator module obtains the interpolation cycle and the acceleration and deceleration model;

[0128] The modeling parameter information of each machining path line segment code is restored into a tool position point trajectory mathematical model, a tool axis point trajectory mathematical model and a tool position point and tool axis point correlation function;

[0129] Determine the interpolation step length, segment the tool position point trajectory model of the machining path line segment according to the interpolation step length, and obtain the interpolation tool position point, wherein the arc angle of the tool axis direction change is segmented for the zero-length line segment;

[0130] The corresponding interpolation point on the tool axis point trajectory model is determined by the tool position point and tool axis point correlation function, the interpolation tool axis point coordinates and tool axis vector information are obtained, and the interpolation tool position point coordinates and tool axis vector data information are stored in an interpolation step list.

[0131] The technical solution of this embodiment is local path interpolation. The amount of data after interpolation is relatively small (regardless of the total processing path length), and the stability of data transmission between the upper and lower computers is not high; the data processing after the pause is simple and the response is fast; for the processing technology that needs to collect a lot of feedback signals in real time and adjust the processing data, the real-time performance is good, and it is easier to achieve the requirements of high speed and high precision. The strategy framework for interpolation in the lower computer is relatively close to the products on the market, and only the interface between the lower computer and the upper computer (such as the G code program format and the program interpreter) needs to be customized and developed.

[0132] Preferably, the interpolation strategy for interpolation performed on the lower computer further includes executing the following steps on the lower computer:

[0133] Based on the acceleration and deceleration mode, the interpolator takes the theoretical processing speed on the tool position path segment as the maximum value, the theoretical processing speed at the end point of the path segment as the starting point, and aims to obtain a continuous and smooth processing speed. It gradually adjusts the theoretical processing speed corresponding to each interpolated tool position in both directions toward the midpoint of the path segment.

[0134] The technical solution of this embodiment accurately adjusts the theoretical processing speed through the acceleration and deceleration mode, ensuring the stability of the tool during the processing. The continuous and smooth processing speed reduces the vibration and impact during the processing, which helps to improve the quality of the processed surface. By interpolating in the lower computer, the calculation burden of the upper computer can be reduced, the processing path can be more optimized, and the processing efficiency can be improved. The lower computer is usually closer to the control link of the machine tool, which can achieve a faster response speed and reduce the waiting time during processing. The application of the acceleration and deceleration mode ensures the stability of the speed change during the processing and avoids the system instability caused by the sudden change of speed. By gradually adjusting the processing speed, the overshoot and oscillation phenomenon of the system during acceleration or deceleration can be reduced.

[0135] This embodiment also has processes such as expressing processing paths, geometric interpolation, IO interpolation, and inverse solution operations. The specific methods / processes are basically the same as those in the first embodiment, except that, in this embodiment, interpolation is performed in the lower computer.

[0136] Third embodiment

[0137] In some solutions of the first embodiment, the specific method of the strategy for interpolation in the upper computer is specifically disclosed. In some solutions of the second embodiment, the specific method of the strategy for interpolation in the lower computer is specifically disclosed. The technical solution provided in this embodiment is described in detail in Figure 4 The method of performing rough interpolation on the upper computer and fine interpolation on the lower computer further includes executing the following steps on the upper computer:

[0138] The coarse interpolation module of the host computer obtains the processing path information, including the tool position point trajectory model, the tool axis point trajectory model and the tool position point and tool axis point correlation function, by sharing memory with the CAM module; or the modeling parameters of the above models are transferred from the CAM module to the coarse interpolation module by data interaction, and then the modeling parameters are restored to the mathematical model; the above data interaction method can adopt the text file interaction method;

[0139] Determine the theoretical coarse interpolation step length according to the coarse interpolation accuracy, divide the arc length of each line segment in the machining path line segment list by the theoretical coarse interpolation step length, and round it to N, and divide the arc length of the line segment by N to obtain the actual coarse interpolation step length L;

[0140] The line segment is segmented using the actual interpolation step length L. The tool position trajectory model is first segmented equally to obtain the interpolation tool position.

[0141] Find the interpolation point on the tool axis point trajectory model 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;

[0142] The sublist of N segments generated after the rough interpolation of a single path segment is stored in the processing path segment list to replace the segment before interpolation; wherein the speed of each segment in the sublist is the same as the speed of the segment before interpolation;

[0143] And / or, where the speeds of adjacent line segments suddenly change and the movement directions suddenly change, the speeds of adjacent line segments are adjusted with the goal of speed smoothing.

[0144] When the strategy of coarse interpolation of the host computer and fine interpolation of the lower computer is adopted, the technical solution of this embodiment can reduce the calculation burden of fine interpolation of the lower computer by performing coarse interpolation on the host computer. The coarse interpolation algorithm is placed in the software of the host computer, which is easy to debug, update, upgrade and maintain. The amount of data after coarse interpolation is much smaller than the amount of data interpolated on the host computer, and the stability requirements for data transmission between the upper and lower computers are low. For processing techniques that require real-time collection of multiple feedback signals and adjustment of processing data, the real-time performance is good and it is easier to achieve high-speed and high-precision requirements. Coarse interpolation calculation can be implemented in the CAM module, and the three-dimensional model of the workpiece can be obtained during interpolation, and nonlinear errors will not be caused by the lack of the three-dimensional model of the workpiece; fine interpolation calculation cannot be implemented in the CAM module, and the three-dimensional model of the workpiece cannot be obtained during interpolation. Nonlinear errors will be caused by the lack of the three-dimensional model of the workpiece during interpolation, but because of coarse interpolation, this nonlinear error is much smaller than the method of directly interpolating on the lower computer. And the data processing after the pause is simple and the response is fast. For processing techniques that require real-time collection of many feedback signals and adjustment of processing data, the real-time performance is good and it is easier to achieve high speed and high precision requirements. Coarse interpolation shares the complex calculations, and fine interpolation does not require very complex calculations, and the problem that the amount of calculation is limited by the interpolation cycle is alleviated. In addition, this embodiment provides text file interaction and other methods to increase the compatibility and flexibility of the system with other software (such as CAM systems). The interpolation tasks of the upper computer and the lower computer are separated, so that they can be adjusted according to different processing requirements and machine tool performance.

[0145] Preferably, the performing of coarse interpolation on the upper computer and fine interpolation on the lower computer further includes executing the following steps on the lower computer:

[0146] The fine interpolation module of the lower computer obtains the list information of the machining path line segments after the rough interpolation, including the tool position point trajectory model, the tool axis point trajectory model and the tool position point and tool axis point correlation function information, by sharing memory with the rough interpolation module of the upper computer; or the modeling parameters of the above models are transferred from the rough interpolation module to the fine interpolation module by data interaction, and then the modeling parameters are restored to the mathematical model; the above data interaction method can adopt the text file interaction method;

[0147] Among them, if the modeling parameters of the above-mentioned model are transferred from the rough interpolation module to the fine interpolation module by means of data interaction, the processing path segments are stored in the memory of the lower computer in the form of code, and the code contains the modeling parameter information of the processing path model. The code parser of the lower computer takes out N lines of code from the memory each time and converts them into a processing path segment array, and inputs the array into the fine interpolator module. At the same time, the fine interpolator module obtains the interpolation cycle and the acceleration and deceleration model;

[0148] The modeling parameter information of each machining path line segment code is restored into a tool position point trajectory mathematical model, a tool axis point trajectory mathematical model and a tool position point and tool axis point correlation function;

[0149] Determine the interpolation step length, segment the tool position point trajectory model of the machining path according to the interpolation step length, and obtain the interpolation tool position point, wherein the arc angle of the tool axis direction change is segmented for the zero-length line segment;

[0150] The corresponding interpolation point on the tool axis point trajectory model is determined by the tool position point and tool axis point association function, the interpolation tool axis point coordinates and tool axis vector information are obtained, and the interpolation tool position point coordinates and tool axis vector data information are stored in an interpolation step array.

[0151] The fine interpolation performed on the lower computer in this embodiment is based on the rough interpolation result of the upper computer, further refines the processing path, and realizes more accurate trajectory planning by restoring the modeling parameter information to a mathematical model and considering the association between the tool position point and the tool axis point in the fine interpolation. The fine interpolation module of the lower computer can efficiently process the data after rough interpolation, reduce the data processing time, and improve the processing efficiency. The code parser is used to quickly convert the processing path segment array, which improves the response speed and processing efficiency of the lower computer. This embodiment also ensures the stability of data interaction between the upper and lower computers through shared memory or text file interaction, and reduces data transmission errors. The tool position point and tool axis point in the fine interpolation are smoothly associated, making the tool movement smoother and improving the finish of the processed surface. The fine interpolation strategy can be adjusted according to different processing requirements, increasing the flexibility of the system. The fine interpolation module can be optimized according to the computing power of the lower computer and the performance of the machine tool to adapt to different processing environments. The processing of zero-length segments during the fine interpolation process ensures the continuity of the processing path and avoids possible processing interruptions.

[0152] Preferably, the performing of coarse interpolation on the upper computer and fine interpolation on the lower computer further comprises:

[0153] The host computer performs the following steps:

[0154] The upper computer generates and outputs a processing program for the list data obtained after rough interpolation and sends it to the lower computer;

[0155] The lower computer performs the following steps:

[0156] Acquire the machining program to execute the fine interpolation operation, and perform speed smoothing processing after the fine interpolation;

[0157] The inverse solver is imported, and the inverse solver calculates the position information of each physical axis from the tool position coordinates of the interpolated tool position and the tool axis vector information according to the machine tool inverse motion algorithm.

[0158] The machining program generated by the host computer in this embodiment is based on the result of rough interpolation, which ensures the accuracy of the tool trajectory. The lower computer performs fine interpolation on this basis, further refines the machining path, and improves the machining accuracy. The speed smoothing after fine interpolation reduces the impact and vibration during the machining process and improves the quality of the machined surface. The rough interpolation of the host computer and the fine interpolation of the lower computer work together to optimize the machining path, reduce unnecessary movement, and improve machining efficiency.

[0159] In some embodiments, a zero-length line segment is added to the endpoint of the path segment to set the theoretical processing speed of the path segment endpoint and the change information of the tool axis vector; wherein the theoretical processing speed of the zero-length line segment is used for adjusting the above processing speed.

[0160] By adding zero-length segments at the endpoints of the path segments, the theoretical processing speed can be accurately set and controlled, making the tool speed change smoother during the processing, reducing the processing error caused by the speed mutation, and improving the processing accuracy. Smooth speed changes reduce vibration and impact during the processing, thereby improving the quality of the processed surface.

[0161] This embodiment also has processes such as expressing processing paths, geometric interpolation, IO interpolation, and inverse solution operations. The specific methods / processes are basically the same as those in the first embodiment. The difference is that in this embodiment, coarse interpolation is performed on the upper computer and further fine interpolation is performed on the lower computer.

[0162] Fourth embodiment

[0163] This embodiment is applicable to the first to third embodiments. When interpolation control is performed on a flexible tool, the offset required for reverse compensation is calculated based on a predictive mathematical model and preset process parameters. 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 machining process:

[0164] 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;

[0165] 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;

[0166] 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;

[0167] 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;

[0168] According to the values ​​of the second component and the fourth component, the final optimized tool axis vector is synthesized.

[0169] The calling prediction mathematical model for prediction includes:

[0170] Determine the current cutting speed in the water jet cutting scenario;

[0171] The cutting speed of each point on the cutting path is calculated based on the mathematical model corresponding to the ruled surface and the preset processing parameters.

[0172] Where, v is the cutting speed, Nm is the material machinability parameter, Pw is the water pressure, is the water flow rate, is the abrasive flow rate, Cs is the proportional factor, q is the cutting quality level, H is the material thickness, and D is the jet beam diameter. In the embodiment of the present application, Pw, The specific value corresponding to the superscript D is not limited in the embodiments of the present application, and the specific values ​​in the above formula are only examples.

[0173] The calling of the first prediction mathematical model to calculate the drag amount generated by cutting the workpiece according to the target parameter information of the current position point includes:

[0174] Get the current cutting speed, and combine the material thickness, material type, and process parameter information at the current position to calculate the drag amount caused by water jet cutting as follows:

[0175]

[0176] Among them, J(h) is the back-support amount, P is the water pressure, is the abrasive flow rate, h is the cutting depth, and v is the cutting speed. In the embodiment of the present application, the fixed values ​​of each parameter can be predetermined according to demand or experiment, etc., and the embodiment of the present application is not limited to this, and the specific values ​​in the above formula are only examples.

[0177] The calling of the second prediction mathematical model to calculate the lateral taper produced by cutting the workpiece according to the target parameter information of the current position point includes:

[0178] Get the current cutting speed and material thickness, and calculate the current lateral taper angle:

[0179]

[0180] Wherein, TA is the lateral taper produced by cutting, V is the cutting speed, and H is the thickness of the material being cut at the current cutting point. In the embodiment of the present application, the fixed values ​​of each parameter can be predetermined according to demand or experiment, etc., and the embodiment of the present application is not limited to this, and the specific values ​​in the above formula are only examples.

[0181] In one embodiment, the initial tool axis vector is determined according to the generatrix of the ruled surface to be processed or the preset cutting direction, including: if the upper edge curve and the lower edge curve of the ruled surface are simple geometric curves, the upper edge curve and the lower edge curve are perpendicular to the processing surface and offset outward by a tool radius; if the upper edge curve and the lower edge curve of the ruled surface are not simple geometric curves, each ruled surface is discretized into a combination of straight generatrixes; the straight generatrix group is perpendicular to the processing surface and offset outward by a tool radius, and the upper point of the offset straight generatrix group is fitted as the upper edge curve as the trajectory curve of the tool position point, and the lower point of the straight generatrix group is fitted as the lower edge curve as the trajectory curve of the tool axis point. If the upper edge curve or the lower edge curve is a simple geometric curve, it is not necessary to determine its parameter equation by using a curve fitting method, but its parameters can be directly determined by using an existing function expression as its mathematical model. Among them, the special case of the mathematical model of a simple geometric curve is an arc, and the parameter equation of the arc is x(u)=cos(u), y(u)=sin(u). If the upper edge curve or the lower edge curve is not a simple geometric curve, but a complex curve, it is necessary to perform curve fitting. Specifically, any available method can be used to perform curve fitting on the upper edge curve and the lower edge curve, and then obtain its mathematical model, which is not limited to this embodiment of the present application. A special case of the mathematical model of a complex curve is a non-uniform rational B-spline (NonUniformRationalB-Splines, NURBS) curve parameter equation. From the above analysis, it can be seen that in the embodiment of the present application, the mathematical model of the upper edge curve and the mathematical model of the lower edge curve can correspond to a straight line or circular arc or spline curve, or can correspond to one or a group of other complex functions, or correspond to a database, etc. Moreover, in practical applications, the upper edge curve and the lower edge curve corresponding to the same straight surface can be the same or different, which is not limited to this embodiment of the present application.

[0182] In one embodiment, the initial tool axis vector is determined according to the generatrix of the ruled surface to be processed or the preset cutting direction, including: if the upper edge curve and the lower edge curve of the ruled surface are simple geometric curves, the upper edge curve and the lower edge curve are perpendicular to the processing surface and offset outward by a tool radius; if the upper edge curve and the lower edge curve of the ruled surface are not simple geometric curves, each ruled surface is discretized into a combination of straight generatrixes; the straight generatrix group is perpendicular to the processing surface and offset outward by a tool radius, and the upper point of the offset straight generatrix group is fitted as the upper edge curve as the trajectory curve of the tool position point, and the lower point of the straight generatrix group is fitted as the lower edge curve as the trajectory curve of the tool axis point. If the upper edge curve or the lower edge curve is a simple geometric curve, it is not necessary to determine its parameter equation by using a curve fitting method, but its parameters can be directly determined by using an existing function expression as its mathematical model. Among them, the special case of the mathematical model of a simple geometric curve is an arc, and the parameter equation of the arc is x(u)=cos(u), y(u)=sin(u). If the upper edge curve or the lower edge curve is not a simple geometric curve, but a complex curve, it is necessary to perform curve fitting. Specifically, any available method can be used to perform curve fitting on the upper edge curve and the lower edge curve, and then obtain its mathematical model, which is not limited to this embodiment of the present application. A special case of the mathematical model of a complex curve is a non-uniform rational B-spline (Non Uniform Rational B-Splines, NURBS) curve parameter equation. From the above analysis, it can be seen that in the embodiment of the present application, the mathematical model of the upper edge curve and the mathematical model of the lower edge curve can correspond to a straight line or circular arc or spline curve, or can correspond to one or a group of other complex functions, or correspond to a database, etc. Moreover, in practical applications, the upper edge curve and the lower edge curve corresponding to the same straight surface can be the same or different, which is not limited to this embodiment of the present application.

[0183] Preferably, when interpolation control is performed on a rigid tool, it is determined whether the tool is deformed by force during the machining process according to the initial tool axis vector and the workpiece model when a machining path is generated and the initial tool axis vector is executed. When the initial tool axis vector is deformed by force during the machining path, the tool force deformation amount that needs to be reversely compensated is calculated based on the machining feature data 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 based on the tool force deformation amount formula:

[0184]

[0185] 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;

[0186] 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;

[0187] The processing characteristic data include three cutting elements, topographical characteristics of the processed surface, machine tool errors and data related to the processing technology.

[0188] 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.

[0189] The core idea of ​​the present invention is to consider multiple models based on multiple interpolation strategies to perform interpolation optimization on the machining path of the machining surface. Based on three interpolation strategies, and on the basis of the tool position point trajectory curve model, the tool axis point trajectory curve model, and the tool position point and tool axis point correlation function, iterative interpolation of the geometric model and the speed model, and appropriate optimization adjustment of the tool axis by the process model are comprehensively considered. The above multiple models are optimized to improve the control accuracy of the interpolation and reduce the machining error.

[0190] Based on the same concept, the present invention also provides a machine tool, comprising any one of the above-mentioned multi-model-based machining path interpolation numerical control systems.

[0191] If 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, and the computer software is stored in a storage medium, including several instructions to enable 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., various media that can store program code.

[0192] 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.

[0193] 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.< / pathstep> < / entity> < / entity>

Claims

1. A machining path interpolation numerical control system based on multiple models, characterized in that: include: A memory, for acquiring and storing machining path information and interpolated step information, wherein the machining path information at least includes a tool position point trajectory model, a tool axis point trajectory model, and a tool position point and tool axis point correlation function; An interpolator, based on a selected interpolation strategy, reads the processing path information from the memory to perform iterative interpolation of geometry and processing speed, wherein the geometric interpolation decomposes each processing path on the processing path into interpolation steps according to a tool position point trajectory model, a tool axis point trajectory model, and a correlation function, arranges the data of all interpolation steps into a tool position point list according to a processing sequence, and then performs processing speed setting, and sets the processing speed based on the interpolated tool position point after geometric interpolation; The interpolation strategy includes: interpolation on the upper computer, interpolation on the lower computer, and rough interpolation on the upper computer and fine interpolation on the lower computer; The inverse solver calculates and stores the position information of each physical axis from the tool position position of the interpolated tool position and the tool axis vector direction; Driver generates and outputs motion control and / or IO control commands to drive the machine tool axes and supporting equipment.

2. The multi-model based machining path interpolation numerical control system according to claim 1, characterized in that: The interpolation strategy for interpolation on the host computer further includes executing the following steps on the host computer: The interpolation module of the host computer obtains the processing path information, including the tool position point trajectory model, the tool axis point trajectory model and the tool position point and tool axis point correlation function, by sharing memory with the CAM module; or the modeling parameters of the above models are transferred from the CAM module to the interpolation module by data interaction, and then the modeling parameters are restored to the mathematical model; the above data interaction method can adopt the text file interaction method; Determine the interpolation step length according to the interpolation cycle and / or the control accuracy and / or the theoretical processing speed; The interpolation step length is used to segment the tool position point trajectory curve of the machining path line segment to obtain the interpolation tool position point; Based on the correlation function between the tool position point and the tool axis point, the corresponding interpolation point on the tool axis point trajectory model is determined, and the interpolation tool axis point coordinates and tool axis vector information corresponding to the interpolation tool position point are obtained; The interpolation tool position coordinates and tool axis vector data information are stored in an interpolation step list.

3. The multi-model based machining path interpolation numerical control system according to claim 2, characterized in that: The interpolation strategy for interpolation on the host computer further includes executing the following steps on the host computer: Based on the acceleration limit and / or acceleration / deceleration model, the theoretical processing speed on the tool position path segment is taken as the maximum value, the theoretical processing speed at the end point of the path segment is taken as the starting point, and the theoretical processing speed corresponding to each interpolation tool position is gradually adjusted in the direction of the midpoint of the path segment in both directions in order to obtain a continuous and smooth processing speed; And / or, adding a zero-length line segment at the endpoint of the path segment to set the theoretical processing speed of the path segment endpoint and the change of the tool axis vector; wherein the theoretical processing speed of the zero-length line segment is used for adjusting the above processing speed.

4. The multi-model based machining path interpolation numerical control system according to claim 1, characterized in that: The interpolation strategy for interpolation on the lower computer further includes executing the following steps on the lower computer: The processing path segments are stored in the memory of the lower computer in the form of code, and the code contains the modeling parameter information of the processing path model. The code parser of the lower computer takes out N lines of code from the memory each time and converts them into a processing path segment array, and inputs the array into the interpolator module. At the same time, the interpolator module obtains the interpolation cycle and the acceleration and deceleration model; The modeling parameter information of each machining path line segment code is restored into a tool position point trajectory mathematical model, a tool axis point trajectory mathematical model and a tool position point and tool axis point correlation function; Determine the interpolation step length, segment the tool position point trajectory model of the machining path line segment according to the interpolation step length, and obtain the interpolation tool position point, wherein the arc angle of the tool axis direction change is segmented for the zero-length line segment; The corresponding interpolation point on the tool axis point trajectory model is determined by the tool position point and tool axis point correlation function, the interpolation tool axis point coordinates and tool axis vector information are obtained, and the interpolation tool position point coordinates and tool axis vector data information are stored in an interpolation step list.

5. The multi-model based machining path interpolation numerical control system according to claim 4, characterized in that: The interpolation strategy for interpolation on the lower computer further includes executing the following steps on the lower computer: Based on the acceleration and deceleration mode, the interpolator takes the theoretical processing speed on the tool position path segment as the maximum value, the theoretical processing speed at the end point of the path segment as the starting point, and aims to obtain a continuous and smooth processing speed. It gradually adjusts the theoretical processing speed corresponding to each interpolated tool position in both directions toward the midpoint of the path segment.

6. The multi-model based machining path interpolation numerical control system according to claim 1, characterized in that: The method of performing rough interpolation on the upper computer and fine interpolation on the lower computer further includes executing the following steps on the upper computer: The coarse interpolation module of the host computer obtains the processing path information, including the tool position point trajectory model, the tool axis point trajectory model and the tool position point and tool axis point correlation function, by sharing memory with the CAM module; or the modeling parameters of the above models are transferred from the CAM module to the coarse interpolation module by data interaction, and then the modeling parameters are restored to the mathematical model; the above data interaction method can adopt the text file interaction method; Determine the theoretical coarse interpolation step length according to the coarse interpolation accuracy, divide the arc length of each line segment in the machining path line segment list by the theoretical coarse interpolation step length, and round it to N, and divide the arc length of the line segment by N to obtain the actual coarse interpolation step length L; The line segment is segmented using the actual interpolation step length L. The tool position trajectory model is first segmented equally to obtain the interpolation tool position. Find the interpolation point on the tool axis point trajectory model 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; The sublist of N segments generated after the rough interpolation of a single path segment is stored in the processing path segment list to replace the segment before interpolation; The speed of each line segment in the sublist is the same as the speed of the line segment before interpolation; And / or, where the speeds of adjacent line segments suddenly change and the movement directions suddenly change, the speeds of adjacent line segments are adjusted with the goal of speed smoothing.

7. The multi-model based machining path interpolation numerical control system according to claim 6, characterized in that: The method of performing rough interpolation on the upper computer and fine interpolation on the lower computer further includes executing the following steps on the lower computer: The fine interpolation module of the lower computer obtains the list information of the machining path line segments after the rough interpolation, including the tool position point trajectory model, the tool axis point trajectory model and the tool position point and tool axis point correlation function information, by sharing memory with the rough interpolation module of the upper computer; or the modeling parameters of the above models are transferred from the rough interpolation module to the fine interpolation module by data interaction, and then the modeling parameters are restored to the mathematical model; the above data interaction method can adopt the text file interaction method; Among them, if the modeling parameters of the above-mentioned model are transferred from the rough interpolation module to the fine interpolation module by means of data interaction, the processing path segments are stored in the memory of the lower computer in the form of code, and the code contains the modeling parameter information of the processing path model. The code parser of the lower computer takes out N lines of code from the memory each time and converts them into a processing path segment array, and inputs the array into the fine interpolator module. At the same time, the fine interpolator module obtains the interpolation cycle and the acceleration and deceleration model; The modeling parameter information of each machining path line segment code is restored into a tool position point trajectory mathematical model, a tool axis point trajectory mathematical model and a tool position point and tool axis point correlation function; Determine the fine interpolation step length, segment the tool position point trajectory model of the machining path according to the fine interpolation step length, and obtain the fine interpolation tool position point, wherein the arc angle of the tool axis direction change is segmented for the zero-length line segment; The corresponding interpolation point on the tool axis point trajectory model is determined by the tool position point and tool axis point association function, the interpolation tool axis point coordinates and tool axis vector information are obtained, and the interpolation tool position point coordinates and tool axis vector data information are stored in an interpolation step array.

8. The multi-model based machining path interpolation numerical control system according to claim 6, characterized in that: The performing of rough interpolation on the upper computer and fine interpolation on the lower computer further comprises: The host computer performs the following steps: The upper computer generates and outputs a processing program for the list data obtained after rough interpolation and sends it to the lower computer; The lower computer performs the following steps: Acquire the machining program to execute the fine interpolation operation, and perform speed smoothing processing after the fine interpolation; The inverse solver is imported, and the inverse solver calculates the position information of each physical axis from the tool position coordinates of the interpolated tool position and the tool axis vector information according to the machine tool inverse motion algorithm.

9. The multi-model based machining path interpolation numerical control system according to claim 1, characterized in that: A zero-length line segment is added to the endpoint of the path segment to set the theoretical processing speed of the path segment endpoint and the change information of the tool axis vector; wherein the theoretical processing speed of the zero-length line segment is used for adjusting the above processing speed.

10. The multi-model based machining path interpolation numerical control system according to claim 1, characterized in that: When interpolation control is performed on a flexible tool, the offset required for reverse compensation is calculated based on the predicted mathematical model and the preset process parameters, and the offset initial tool axis vector is optimized 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.

11. The multi-model based machining path interpolation numerical control system according to claim 1, characterized in that: When interpolation control is performed on a rigid tool, it is determined 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, the tool force deformation amount that needs to be reversely compensated is calculated based on the machining feature data of the machining 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 based on 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.

12. A machine tool, characterized in that: A multi-model based machining path interpolation CNC system comprising any one of claims 1 to 11.

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