A method, system, apparatus, and medium for hobbing an internal spline gear

Abstract

The application provides a method, system, device and medium for gear cutting of an internal spline gear, the method comprising the following steps: obtaining theoretical tooth profile parameters and tooth surface modification parameters of an internal spline gear workpiece, constructing and analyzing a parameterized tooth surface topology modification model, and generating a helical feed trajectory of a gear cutting tool; determining a preset cutting line speed based on the trajectory, and obtaining target set values of a feed speed, a spindle speed and a rotational angle speed of a rotary table; calculating a target set value of a driving deflection angle according to a kinematic constraint equation; in the interpolation control process, synchronously obtaining feedback values corresponding to the above parameters based on the cutting line speed; calculating motion deviation amounts of the feedback values and the corresponding target set values, and performing dynamic compensation on each parameter based on a compensation control strategy; and controlling multi-axis linkage of a machine tool to continuously cut the internal spline gear workpiece based on the compensated parameters. The technical solution provided by the application can improve the machining precision and forming quality of the internal spline gear.

Description

Technical Field

[0001] This application relates to the field of gear machining technology, and in particular to a method, system, equipment and medium for turning internal splined gears. Background Technology

[0002] With the rapid development of high-end equipment manufacturing such as automotive powertrains, aerospace, and industrial robots, the demand for key transmission components such as high-load-bearing and high-centering-precision internal splined gears continues to rise, and the requirements for complex gear manufacturing processes are also constantly increasing. How to perform efficient continuous cutting of internal splined gears and simultaneously achieve high-precision machining and composite shaping in a single clamping has become a core requirement for ensuring the performance of transmission components and improving manufacturing efficiency.

[0003] In existing technologies, the forming of internal spline gears is typically achieved through traditional gear shaping processes or five-axis gear turning systems based on set kinematic parameters. For example, when machining on a five-axis CNC machine tool with a gear turning cutter, synchronous cutting is usually performed using a pre-fixed tool deflection angle and feed rate. However, in practical applications, existing gear turning methods based on fixed parameters suffer from several drawbacks when facing high-speed cutting conditions with high-frequency multi-axis linkage. The lack of a closed-loop verification and dynamic adjustment mechanism for the instantaneous dynamic spatial posture of the tool and workpiece leads to risks such as microscopic trajectory mismatch, accumulation of servo tracking errors caused by multi-axis linkage, and spatial interference in complex internal hole machining environments. Furthermore, during high-speed gear turning, the high-speed rotation of the spindle and table, along with their dynamic spatial yaw, generates a gyroscopic effect. The resulting precession torque causes micron-level elastic bending deformation of the tool holder, further exacerbating the deterioration of tooth surface forming accuracy. Summary of the Invention

[0004] In view of this, this application provides a method, system, apparatus and medium for machining internal spline gears to solve the above problems.

[0005] Firstly, a method for turning internal splined gears is provided, applied to a five-axis CNC machine tool. The five-axis CNC machine tool includes a rotary table and a tool spindle system, each having at least one rotational degree of freedom. The internal splined gear workpiece to be machined is clamped on the rotary table, and the turning cutter is mounted on the tool spindle system. The method includes:

[0006] The theoretical tooth profile parameters and tooth surface modification parameters of the internal spline gear workpiece are obtained. A parameterized tooth surface topology modification model is constructed based on the theoretical tooth profile parameters and tooth surface modification parameters. The parameterized tooth surface topology modification model is analyzed by a preset kinematic solution algorithm to generate a helical feed trajectory of the turning cutter along the axial and circumferential coupled motion of the internal spline gear workpiece.

[0007] Based on the helical feed trajectory, the preset cutting line speed is determined, and the first target setting value of the feed speed corresponding to the helical feed trajectory is obtained. Based on the preset cutting line speed, the second target setting value of the spindle speed of the tool spindle system and the third target setting value of the rotational angular velocity of the rotary table are determined.

[0008] Based on the preset kinematic constraint equations, and based on the first target setting value, the second target setting value, and the third target setting value, the fourth target setting value is calculated as the active deflection angle of the cutting tool axis relative to the workpiece axis of the internal spline gear workpiece.

[0009] During the interpolation control process, the preset cutting line speed is used as a reference to synchronously control the rotational angular velocity and spindle speed, and the feedback values ​​corresponding to the active deflection angle, feed rate, spindle speed and rotational angular velocity are obtained respectively.

[0010] Calculate the motion deviation between each feedback value and the corresponding target setting value, and perform dynamic compensation on the active deflection angle, feed rate, spindle speed and rotational angular velocity based on each motion deviation and the preset compensation control strategy. The target setting value includes the first target setting value, the second target setting value, the third target setting value and the fourth target setting value.

[0011] Based on the dynamic compensation of the active deflection angle, feed rate, spindle speed and rotational angular velocity, the tool spindle system and the rotary table are linked to enable the gear cutting cutter to continuously cut the internal spline gear workpiece.

[0012] The above technical solution, by acquiring feedback values ​​of active deflection angle, feed rate, spindle speed and rotational angular velocity in real time during the interpolation control process of the machine tool, and calculating the motion deviation between each feedback value and the pre-planned first to fourth target settings, and then performing dynamic compensation based on the motion deviation, eliminates the risk of spatial interference caused by instantaneous pose deviation during the five-axis linkage high-speed cutting process, and ensures the machining accuracy of the internal spline gear.

[0013] Optionally, a parametric tooth surface topology modification model is constructed based on theoretical tooth profile parameters and tooth surface modification parameters, specifically including:

[0014] The reference theoretical tooth surface equation is constructed based on the theoretical tooth profile parameters;

[0015] Obtain the preset tooth profile convexity, tooth bulge, tooth tip chamfer radius, and tooth root transition radius from the tooth surface modification parameters;

[0016] Based on the tooth profile convexity, tooth bulging, tooth tip chamfer radius, and tooth root transition radius, a multi-maintenance profile parameter matrix is ​​constructed.

[0017] Substitute the multi-maintenance profile parameter matrix into the preset tooth surface deviation function to calculate the spatial deviation compensation mesh;

[0018] The spatial deviation compensation mesh is superimposed onto the reference theoretical tooth surface equation to generate a parameterized tooth surface topology modification model.

[0019] The above technical solution constructs a multi-dimensional matrix by modifying parameters such as tooth profile convexity, tooth bulge, and chamfer transition arc, and then substitutes them into the deviation function to generate a spatial deviation compensation grid, which is then superimposed on the reference tooth surface equation. This allows the final generated helical feed trajectory to directly contain the composite micro-modification amount, thus achieving high-precision composite modification of the internal spline in a single clamping operation.

[0020] Optionally, after generating the helical feed trajectory of the gear cutting tool coupled to the axial and circumferential motion of the internal spline gear workpiece, and before determining the preset cutting speed based on the helical feed trajectory, the method further includes:

[0021] The spiral feed trajectory is parametrically resampled to generate a kinematic sequence containing position, velocity, acceleration, and jerk attributes.

[0022] Extract each motion segment from the kinematic sequence and insert acceleration / deceleration transition segments into each motion segment;

[0023] Based on a preset maximum acceleration threshold, constraint processing is performed on the kinematic sequence after the insertion of the acceleration / deceleration transition segment to obtain a smooth reconstructed trajectory, which is then used as the helical feed trajectory.

[0024] The above technical solution, by resampling the helical feed trajectory including position, velocity, acceleration and jerk attributes, inserting acceleration and deceleration transition segments in each motion segment, and performing smooth constraint processing on the trajectory sequence using the maximum jerk threshold, limits the sudden acceleration changes of the servo axis in the complex trajectory interpolation process, and avoids severe mechanical shock and vibration of the machine tool structure.

[0025] Optionally, based on preset kinematic constraint equations and using the first, second, and third target settings, a fourth target setting is calculated to determine the active deflection angle of the cutting tool axis relative to the workpiece axis of the internal spline gear workpiece. This specifically includes:

[0026] Obtain the average rotation radius of the cutting edge of the gear cutting tool, and obtain the preset inner hole radius of the internal spline gear workpiece;

[0027] Based on the first target setting value, the second target setting value and the average turning radius of the cutting edge, determine the tool side kinematic components including the tool space velocity vector;

[0028] Based on the third target setting value, the preset inner hole radius and the first target setting value, determine the workpiece side kinematic components that include the workpiece composite velocity vector;

[0029] Based on the tool-side kinematic components and the workpiece-side kinematic components, a preset trigonometric function mapping analysis is performed to obtain the fourth target setting value of the active deflection angle.

[0030] The above technical solution extracts the average turning radius of the cutting edge of the tool, the preset inner hole radius of the workpiece, and the corresponding target velocity vector. It then uses trigonometric function mapping to analyze the combined kinematic components of the tool side and the workpiece side, and accurately calculates the safe deflection angle that matches the current specific tool and workpiece dimensions. This prevents physical collisions between the tool and the inner spline hole wall from a geometric and kinematic perspective.

[0031] Optionally, based on the various motion deviations and a preset compensation control strategy, dynamic compensation is performed on the active deflection angle, feed rate, spindle speed, and rotational angular velocity, specifically including:

[0032] Obtain the spatial attitude matrix of the current interpolation cycle generated by the interpolation control, and determine the instantaneous angular velocity vector of each rotation axis in the rotary table and tool spindle system based on the feedback value corresponding to the spindle speed, the feedback value corresponding to the rotational angular velocity, and the spatial attitude matrix.

[0033] Based on the preset moment of inertia tensor and instantaneous angular velocity vector, the gyroscopic effect compensation torque corresponding to each rotation axis is calculated.

[0034] Based on the gyroscopic effect compensation torque and the preset stiffness coefficient, each gyroscopic effect compensation torque is converted into a corresponding kinematic compensation component, and the kinematic compensation component is superimposed on the dynamic compensation performed on the active deflection angle, feed rate, spindle speed and rotational angular velocity.

[0035] The above technical solution extracts the instantaneous angular velocity vector of each rotation axis based on the current spatial attitude matrix and feedback velocity, and calculates the gyroscopic effect compensation torque generated by high-frequency rotation by combining the rotational inertia tensor. Then, it uses the stiffness coefficient to convert it into a kinematic compensation component and superimposes it into dynamic compensation, thereby offsetting the micro-elastic deformation of the tool caused by the dynamic torque under high-speed cutting conditions.

[0036] Optionally, the tool spindle system is linked with the rotary table to enable the gear cutting tool to continuously cut the internal spline gear workpiece, specifically including:

[0037] In each machining pass of continuous cutting, the actual feedback value of the cutting line speed, the feedback value corresponding to the feed speed and the preset radial depth of cut are obtained, and the spindle load current feedback value of the current tool spindle system is obtained. The spindle load current feedback value is used as a characterization parameter of the tool cutting edge state.

[0038] The actual feedback value of the cutting line speed, the feedback value corresponding to the feed speed, the radial depth of cut and the spindle load current feedback value are input into the preset surface roughness prediction model to obtain the surface roughness prediction value for the current machining pass.

[0039] When the predicted surface roughness value is greater than the preset roughness threshold, a fine-tuning compensation instruction is generated for the axial reference surface. The fine-tuning compensation instruction includes a preset step offset along the axial direction of the internal spline gear workpiece. Based on the fine-tuning compensation instruction, axial step compensation is performed on the tool spindle system and the rotary table in the next machining pass.

[0040] The above technical solution collects actual cutting speed parameters, radial depth of cut, and spindle load current that characterizes the wear state of the tool edge. It uses a model to predict the surface roughness of the current pass and automatically triggers a fine-tuning compensation command including axial step offset when the predicted value exceeds the standard, thus establishing an adaptive fine-tuning closed loop based on the actual physical state of the tool and the quality of the machined surface.

[0041] Optionally, after performing axial step compensation on the tool spindle system and rotary table in the next machining pass according to the fine-tuning compensation command, it also includes:

[0042] The measured surface roughness value of a continuous preset number of teeth after axial step compensation is extracted by a preset in-machine measurement unit.

[0043] Each measured surface roughness value is compared with a preset roughness threshold.

[0044] When all measured surface roughness values ​​are less than or equal to the preset roughness threshold, the generation of fine-tuning compensation commands will stop.

[0045] The above technical solution utilizes the on-machine measurement unit to extract the measured surface roughness value after axial step compensation and compare it with the threshold, providing a real physical measurement verification basis for the pre-predictive compensation action. When the measured quality meets the standard, the generation of fine-tuning compensation instructions is automatically terminated, thus forming a complete processing quality verification mechanism with clear steady-state exit conditions.

[0046] Secondly, a system for turning internal splined gears is provided, applied to a five-axis CNC machine tool. The five-axis CNC machine tool includes a rotary table and a tool spindle system. The rotary table and the tool spindle system each have at least one rotational degree of freedom. The internal splined gear workpiece to be machined is clamped on the rotary table, and the turning cutter is mounted on the tool spindle system. The system includes:

[0047] The trajectory planning module is used to obtain the theoretical tooth profile parameters and tooth surface modification parameters of the internal spline gear workpiece, construct a parameterized tooth surface topology modification model based on the theoretical tooth profile parameters and tooth surface modification parameters, and analyze the parameterized tooth surface topology modification model through a preset kinematic solution algorithm to generate a helical feed trajectory of the turning cutter along the axial and circumferential coupled motion of the internal spline gear workpiece.

[0048] The parameter setting module is used to determine the preset cutting line speed based on the helical feed trajectory, and obtain the first target setting value of the feed speed corresponding to the helical feed trajectory. Based on the preset cutting line speed, it determines the second target setting value of the spindle speed of the tool spindle system and the third target setting value of the rotational angular velocity of the rotary table.

[0049] The attitude calculation module is used to calculate the fourth target setting value of the active deflection angle of the cutting tool axis of the gear cutting tool relative to the workpiece axis of the internal spline gear workpiece based on the preset kinematic constraint equations, the first target setting value, the second target setting value, and the third target setting value.

[0050] The status acquisition module is used to synchronously control the rotational angular velocity and spindle speed based on the preset cutting line speed during the interpolation control process, and to obtain the feedback values ​​corresponding to the active deflection angle, feed rate, spindle speed and rotational angular velocity respectively.

[0051] The dynamic compensation module is used to calculate the motion deviation between each feedback value and the corresponding target setting value, and to perform dynamic compensation on the active deflection angle, feed rate, spindle speed and rotational angular velocity based on each motion deviation and the preset compensation control strategy. The target setting value includes a first target setting value, a second target setting value, a third target setting value and a fourth target setting value.

[0052] The linkage cutting module is used to control the linkage between the tool spindle system and the rotary table based on the dynamically compensated active deflection angle, feed rate, spindle speed and rotational angular velocity, so that the gear cutting cutter can continuously cut the internal spline gear workpiece.

[0053] Thirdly, an electronic device is provided, including a digital control core for performing kinematic calculations and dynamic compensation calculations as described in any of the above methods, and sending compensated control commands to a multi-axis servo drive unit via an industrial fieldbus interface to drive physical cutting actions; a programmable logic controller for executing logical action control of the five-axis CNC machine tool; a memory for storing instructions and machining parameter data; a human-machine interface for displaying machining status and receiving operation commands; and an industrial fieldbus interface for communicating with the multi-axis servo drive unit.

[0054] Fourthly, a computer-readable storage medium is provided, the computer-readable storage medium storing instructions that, when executed, perform the method as described in any of the preceding claims.

[0055] In summary, implementing one or more technical solutions provided in this application has at least the following technical effects or advantages:

[0056] By constructing a fully intelligent gear turning architecture encompassing underlying trajectory decoupling, multi-physics field feedforward compensation, and adaptive closed-loop process quality control, this solution overcomes the accuracy limitations caused by traditional CNC gear turning relying on preset static parameters. On one hand, this solution elevates traditional pure geometric trajectory interpolation to a "physical-level" closed-loop servo control that integrates machine tool stiffness, actual tool load, and spatial dynamics effects. This endows general-purpose five-axis machine tools with intelligent attributes of "real-time perception and dynamic correction" for complex machining conditions. This not only significantly reduces trial-and-error time during new product introduction but also avoids wear on the machine tool spindle due to abnormal forces, significantly extending the service life of gear turning tools. On the other hand, this solution eliminates the heavy reliance on specific specialized equipment (such as high-precision gear shapers or broaching machines) for complex internal spline machining. Without increasing the cost of underlying hardware modifications, it greatly expands the process boundaries of general-purpose five-axis CNC machine tools, providing a manufacturing solution that balances production flexibility, machining consistency, and economic benefits for high-load transmission components in high-end equipment manufacturing fields such as aerospace, new energy vehicles, and industrial robots. Attached Figure Description

[0057] Figure 1 This is a flowchart illustrating a method for machining internal spline gears disclosed in this application.

[0058] Figure 2 This is a schematic diagram of a system for turning internal splined gears disclosed in this application;

[0059] Figure 3 This is a schematic diagram of the structure of an electronic device disclosed in this application.

[0060] Explanation of reference numerals in the attached diagram: 201, Trajectory planning module; 202, Parameter setting module; 203, Attitude calculation module; 204, Status acquisition module; 205, Dynamic compensation module; 206, Linked cutting module; 301, Digital control core; 302, Communication bus; 303, Human-machine interface; 304, Industrial fieldbus interface; 305, Memory; 306, Programmable logic controller. Detailed Implementation

[0061] To enable those skilled in the art to better understand the technical solutions in this specification, the technical solutions in the embodiments of this specification will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments.

[0062] In the description of the embodiments of this application, the electronic device can be integrated into the control system of a five-axis CNC machine tool. By calling the program instructions stored in the memory, the coordinated control of each motion axis of the five-axis CNC machine tool can be achieved. For ease of description, the execution subject of the following method steps will be uniformly described using the digital control core in the electronic device as an example. However, in practical applications, this subject constitutes the core control part of the five-axis CNC machine tool.

[0063] In the description of the embodiments of this application, the words "for example" or "for instance" are used to indicate examples, illustrations, or explanations. Any embodiment or design that is described as "for example" or "for instance" in the embodiments of this application should not be construed as being more preferred or advantageous than other embodiments or design options. Rather, the use of the words "for example" or "for instance" is intended to present the relevant concepts in a specific manner.

[0064] In the description of the embodiments of this application, the term "multiple" means two or more. For example, multiple systems means two or more systems, and multiple screen terminals means two or more screen terminals. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the indicated technical features. Thus, a feature defined with "first" or "second" may explicitly or implicitly include one or more of that feature. The terms "comprising," "including," "having," and variations thereof all mean "including but not limited to," unless otherwise specifically emphasized.

[0065] Figure 1 This is a flowchart illustrating a method for turning internal splined gears according to an embodiment of this application. It can be implemented using a digital control system or run on a system for turning internal splined gears. This computer program can be integrated into an application or run as a standalone utility application. The specific steps of a method for turning internal splined gears are described in detail below.

[0066] S101: Obtain the theoretical tooth profile parameters and tooth surface modification parameters of the internal spline gear workpiece, construct a parameterized tooth surface topology modification model based on the theoretical tooth profile parameters and tooth surface modification parameters, and analyze the parameterized tooth surface topology modification model through a preset kinematic solution algorithm to generate a helical feed trajectory of the turning cutter along the axial and circumferential coupled motion of the internal spline gear workpiece.

[0067] For example, in the pre-planning stage of actual gear turning, the digital control core 301 first reads and parses the engineering data of the internal spline drawing. In addition to extracting the basic parameters that determine the macroscopic profile of the gear, the digital control core 301 also simultaneously extracts the microscopic morphological requirements for optimizing the transmission force state. In its internal virtual coordinate system, the digital control core 301 integrates these macroscopic and microscopic features into a three-dimensional target forming surface that meets the preset tolerance zone requirements. Subsequently, relying on the unique staggered axis generating mechanism of gear turning, the built-in kinematics solving module calculates how the cutting edge of the tool forms a conjugate envelope with the target surface, and then reversely derives and plans a composite feed path. On this path, the gear cutting tool must not only penetrate along the axial direction of the workpiece's inner hole, but also strictly cooperate with the circumferential rotation of the workpiece. This final output helical feed trajectory has all the spatial clearance and microscopic shaping offsets embedded in advance at the geometric level, generating a high-precision spatial trajectory coordinate set to guide subsequent servo multi-axis linkage.

[0068] In one possible implementation, a parameterized tooth surface topology modification model is constructed based on theoretical tooth profile parameters and tooth surface modification parameters. Specifically, this includes: constructing a reference theoretical tooth surface equation based on the theoretical tooth profile parameters; obtaining preset tooth profile convexity, tooth bulging, tooth tip chamfer radius, and tooth root transition radius from the tooth surface modification parameters; constructing a multi-dimensional tooth surface modification parameter matrix based on the tooth profile convexity, tooth bulging, tooth tip chamfer radius, and tooth root transition radius; substituting the multi-dimensional tooth surface modification parameter matrix into a preset tooth surface deviation function to calculate a spatial deviation compensation mesh; and superimposing the spatial deviation compensation mesh onto the reference theoretical tooth surface equation to generate the parameterized tooth surface topology modification model.

[0069] In this embodiment, the parametric tooth surface topology modification model refers to a comprehensive three-dimensional mathematical expression that integrates the standard gear geometry with microscopic local morphological variations. It represents the ideal spatial surface that an internal spline gear is expected to machine after specific anti-interference or noise reduction modification design. For example, this model not only defines the macroscopic involute profile of the gear but also precisely defines the three-dimensional coordinate offset of each microscopic coordinate point on the tooth surface relative to its standard theoretical position using a digital mesh, thus providing a unique three-dimensional coordinate reference for subsequent spatial multi-axis interpolation linkage of the gear cutting tool.

[0070] Specifically, firstly, based on macroscopic theoretical tooth profile parameters such as module, pressure angle, and number of teeth, a baseline theoretical tooth surface equation without any microscopic modification is derived and constructed through the involute and tooth line generation mechanism, serving as the geometric basis for subsequent superimposed deformation. Subsequently, to improve the load distribution during gear meshing and eliminate edge stress concentration, several key microscopic design quantities in the tooth surface modification parameters are obtained: tooth profile convexity is used to characterize the slight convex deformation along the tooth height direction, tooth bulging is used to characterize the slight convex deformation along the tooth width axial direction, and the radius of the tooth tip chamfer and the radius of the tooth root transition arc define the smooth transition dimensions of the tooth tip anti-interference clearance region and the tooth root anti-fatigue region, respectively. After extracting the above values, a multi-modality modification parameter matrix is ​​constructed based on the spatial geometric relationship and domain boundaries of the tooth profile convexity, tooth bulging, tooth tip chamfer, and tooth root transition arc radius. ,in For tooth profile convexity measurement, For tooth-shaped bulging, The radius of the chamfered arc at the tooth tip. To determine the radius of the tooth root transition arc, discrete scalar values ​​are transformed into a structured spatial array. Next, this multi-dimensional profile parameter matrix is... Substituting the preset tooth surface deviation function, boundary fitting is performed using spatial interpolation and a surface smoothing transition algorithm to calculate a spatial deviation compensation mesh covering the entire machining domain. This mesh is essentially a set of three-dimensional deviation coordinates containing the minute normal and tangential displacements of each node on the tooth surface, which can be expressed as a deviation distribution function. Where u and w are the normalized spatial coordinates along the tooth height and tooth width directions, respectively. Finally, the spatial deviation compensation mesh calculated above is mapped point-by-point and superimposed onto the aforementioned reference theoretical tooth surface equation using a three-dimensional vector superposition method. In this context, the formula is synthesized through geometric analysis:

[0071]

[0072] in, The unit normal vector of the corresponding coordinate point of the tooth surface is used as the reference theory, so that the originally regular standard involute equation has local topological bulge or depression features, thereby generating the final required parametric tooth surface topology modification model in the underlying geometric space.

[0073] In one possible implementation, after generating the helical feed trajectory of the cutting tool coupled along the axial and circumferential directions of the internal spline gear workpiece, and before determining the preset cutting speed based on the helical feed trajectory, the method further includes: parametrically resampling the helical feed trajectory to generate a kinematic sequence containing position attributes, velocity attributes, acceleration attributes, and jerk attributes; extracting each motion segment from the kinematic sequence and inserting acceleration / deceleration transition segments into each motion segment; performing constraint processing on the kinematic sequence after inserting acceleration / deceleration transition segments based on a preset maximum acceleration / deceleration threshold to obtain a smooth reconstructed trajectory, and using the smooth reconstructed trajectory as the helical feed trajectory.

[0074] Specifically, the initially generated helical feed trajectory is usually a pure geometric trajectory. In high-speed gear turning with multi-axis linkage, if this pure geometric trajectory is directly used as input for interpolation, the abrupt curvature changes between adjacent trajectory segments will cause the machine tool's servo axes to generate infinite acceleration or jerk (jump) during motion switching. By resampling and inserting acceleration / deceleration transition segments (e.g., using S-shaped or polynomial acceleration / deceleration flexible control algorithms), discrete geometric path points are transformed into a continuous kinematic sequence. When inserting acceleration / deceleration transition segments, boundary conditions are matched to ensure that the position, velocity, and acceleration of the transition segment and adjacent motion segments at the connection point remain continuous (i.e., the first and second derivatives of the displacement function are continuous), thereby eliminating microscopic kinematic discontinuities.

[0075] For example, the digital control core 301 pre-obtains the maximum acceleration threshold (i.e., jerk limit) that the machine tool's mechanical structure can withstand. During the constraint processing stage, if the digital control core 301 detects that the jerk of a certain kinematic sequence exceeds the maximum acceleration threshold, it actively lengthens the acceleration / deceleration transition time of that segment or fine-tunes the trajectory corner, thereby transforming rigid impacts into smooth reconstructed trajectories. This limits abrupt acceleration changes of the servo axes during complex topology mesh interpolation from the underlying control algorithm, avoiding machine tool structural vibration and mechanical impact under high-frequency multi-axis linkage.

[0076] S102: Based on the helical feed trajectory, determine the preset cutting line speed and obtain the first target setting value of the feed speed corresponding to the helical feed trajectory. Based on the preset cutting line speed, determine the second target setting value of the spindle speed of the tool spindle system and the third target setting value of the rotational angular velocity of the rotary table.

[0077] In this embodiment, the preset cutting speed refers to the basic linear velocity reference value of the relative motion between the cutting edge and the workpiece contact point when the cutting edge of the gear turning tool continuously removes material in the circumferential direction of the inner hole of the internal spline gear workpiece. It is used to represent the core dynamic boundary index that must be maintained during the machining process to ensure surface roughness quality and tool service life. For example, for a workpiece of a specific material and a gear turning tool with a specific coating, the preset cutting speed is usually set to a constant preset cutting constant, such as 180 m / min, in conjunction with a basic cutting database. This serves as the calculation benchmark for the subsequent reverse derivation of the dynamic speed of each servo rotary axis.

[0078] Specifically, the spatial geometric characteristics and cutting process requirements of the spiral feed trajectory input from the previous step are first analyzed. Based on the machining process standards, a preset cutting speed suitable for the current machining conditions is determined. Simultaneously, the displacement change rate of the spiral feed trajectory in the time dimension is analyzed. Specifically, the first-order numerical differentiation of the coordinate components of each node of the spiral feed trajectory along the workpiece axis with respect to the interpolation time is performed to obtain the first target set value of the feed speed characterizing the tool displacement along the workpiece axis per unit time. Subsequently, using this preset cutting speed as the absolute calculation benchmark, the rotational speed is calculated by combining the gear generating kinematics principle in gear turning. On the one hand, by utilizing the mathematical mapping relationship of circumferential motion between the preset cutting speed and the nominal cutting diameter of the gear cutting tool, the tool rotation frequency required to maintain the cutting speed is derived in reverse, thereby determining the second target setting value of the spindle speed of the tool spindle system. On the other hand, based on the strict theoretical speed ratio (i.e., theoretical tooth ratio) synchronous meshing relationship between the tool and the workpiece in the gear turning process, combined with the distribution requirements of the preset cutting speed in the circumferential direction of the workpiece's inner hole, the rotational angular frequency required to be maintained at the end of the worktable is calculated synchronously, thereby determining the third target setting value of the rotational angular velocity of the rotary worktable. After the above kinematic calculation including velocity vector decomposition and theoretical speed ratio mapping, the preset cutting speed is finally determined based on the helical feed trajectory, and the first target setting value of the feed speed corresponding to the helical feed trajectory is obtained. Based on this preset cutting speed, the second target setting value of the spindle speed of the tool spindle system and the third target setting value of the rotational angular velocity of the rotary worktable are determined.

[0079] S103: Based on the preset kinematic constraint equations, and based on the first target setting value, the second target setting value, and the third target setting value, calculate the fourth target setting value of the active deflection angle of the cutting tool axis relative to the workpiece axis of the internal spline gear workpiece.

[0080] For example, gear turning is physically a conjugate generating motion of spatially intersecting gears. After receiving the pre-planned linear feed and dual-axis rotation speeds (i.e., the first to third target settings), the CNC core 301 incorporates these one-dimensional kinematic parameters into a pre-set macroscopic spatial envelope model. This model contains strictly satisfying cutting edge conjugate envelope boundaries and spatial avoidance constraint equations. The CNC core 301 solves these equations using a low-level algorithm, mapping the independently operating axis speed parameters to a unified spatial geometric posture, thereby calculating the absolute spatial angle (i.e., axis intersection angle) at which the tool axis must be tilted relative to the workpiece hole centerline. For example, for internal splines with specific helix angle and depth of cut requirements, the CNC core 301 integrates these speed settings and automatically derives a spatial cross-offset angle such as 15.5 degrees to ensure that the direction of the relative cutting speed is strictly tangent to the helix of the spline tooth groove, completing the crucial transition from time / velocity domain commands to three-dimensional spatial posture domain commands.

[0081] In one possible implementation, based on a preset kinematic constraint equation and a first, second, and third target setpoint, a fourth target setpoint is calculated to determine the active deflection angle of the gear cutting tool axis relative to the workpiece axis of the internal spline gear workpiece. Specifically, this includes: obtaining the average rotation radius of the cutting edge of the gear cutting tool and a preset inner hole radius of the internal spline gear workpiece; determining the tool-side kinematic components, including the tool space velocity vector, based on the first, second, and average rotation radius of the cutting edge; determining the workpiece-side kinematic components, including the workpiece composite velocity vector, based on the third target setpoint, the preset inner hole radius, and the first target setpoint; and performing a preset trigonometric function mapping analysis based on the tool-side and workpiece-side kinematic components to obtain the fourth target setpoint for the active deflection angle.

[0082] In this embodiment, the fourth target setting value of the active deflection angle refers to the absolute theoretical reference benchmark of the tilt angle between the tool spindle centerline and the workpiece rotation centerline in the three-dimensional coordinate system, which must be maintained during the five-axis linkage gear turning process so that the cutting edge of the gear cutting tool can accurately generate cuts with the inner wall of the internal spline gear workpiece according to the expected helical feed trajectory without physical spatial interference. For example, when machining an internal spline with a length-to-diameter ratio greater than a preset threshold, since the safety clearance between the tool and the hole wall is less than the preset safety clearance distance, tool holder interference and collision are likely to occur if precise spatial angle deflection is not performed. Therefore, it is necessary to pre-calculate the fourth target setting value of the active deflection angle as a specific angle (e.g., 15.5 degrees) to serve as the sole source of geometric control commands for subsequent machine tool rotary axes (such as the A-axis or B-axis) to perform attitude interpolation and closed-loop servo fine-tuning.

[0083] Specifically, after determining the basic speed parameters of each motion axis, in order to eliminate interference blind spots from the underlying physical space and satisfy the gear forming principle, the average rotation radius of the cutting edge of the gear cutting tool is accurately obtained by first reading the three-dimensional geometric dimension information of the pre-imported tool file and workpiece drawing, and obtaining the preset inner hole radius of the internal spline gear workpiece, which characterizes the physical constraint boundary of the workpiece machining space. Subsequently, based on the first target set value reflecting the cutting axial displacement rate and the second target set value reflecting the tool rotation frequency, and combined with the aforementioned average rotation radius of the cutting edge, vector synthesis calculation is performed to derive the combined linear velocity of the tangential rotation and axial feed of the cutting edge in space, thereby determining the tool space velocity vector. The tool side kinematic components (where These are the components of the tool side velocity vector along each linear axis of the machine tool. Simultaneously, based on the third target setting value reflecting the workpiece's generating rotation reference, the preset inner hole radius defining spatial interference constraints, and combined with the aforementioned first target setting value, relative kinematic transformation is performed to derive the instantaneous linear velocity characteristics of the inner hole wall generated by the table rotation and relative feed motion, thereby determining the component containing the workpiece's composite velocity vector. The workpiece-side kinematic components, of which These are the three-dimensional orthogonal components of the workpiece-side composite velocity vector in the corresponding machine tool space coordinate system. Finally, based on the fundamental laws of gear meshing and the preset kinematic constraint equations that ensure the relative cutting velocity direction is strictly tangent to the expected tooth helix angle, the tool-side kinematic components and workpiece-side kinematic components established in different coordinate reference systems are placed in the same relative cutting velocity field. The spatial velocity triangle rule is used to construct the relative cutting velocity vector equation. It then performs a preset trigonometric function mapping analysis, using the inverse trigonometric function geometric projection equation:

[0084]

[0085] The spatial tilt angle that allows the tool to both complete its generating motion and safely avoid obstacles is calculated, and from this, the fourth target setpoint for the active deflection angle is finally obtained (here, the fourth target setpoint corresponds to the solved spatial tilt angle). ).

[0086] At this point, the target settings for feed rate, spindle speed, rotational angular velocity, and active deflection angle obtained from the analysis of the helical feed trajectory have been determined, and the 301 digital control core controls the machine tool to enter the multi-axis linkage interpolation execution stage based on the above target settings.

[0087] S104: During the interpolation control process, the rotational angular velocity and spindle speed are synchronously controlled based on the preset cutting line speed, and the feedback values ​​corresponding to the active deflection angle, feed rate, spindle speed and rotational angular velocity are obtained respectively.

[0088] In this embodiment, the feedback value refers to the actual physical motion state measurement data collected and transmitted in real time by high-precision detection elements (such as grating rulers or absolute encoders) of the underlying servo drive system when a five-axis CNC machine tool executes the linkage control commands for each axis. This data represents the actual execution result and actual pose state of each motion axis of the machine tool after being disturbed by physical factors within the current micro-interpolation cycle. For example, for the A-axis or B-axis controlling tool deflection, the command-set angle may be 15.5 degrees. However, under the resistance generated by the high-speed cutting load, the actual deflection angle read in real time by the circular grating may be 15.48 degrees. This 15.48 degrees is the feedback value for that instantaneous cycle, and it is the core objective basis for subsequently triggering closed-loop dynamic fine-tuning.

[0089] Specifically, during the interpolation control process at the microscopic time scale, when the macroscopically continuous helical feed trajectory is discretized into tiny instruction steps executable by the servo driver, a preset cutting speed is always used as a benchmark to ensure the quality of tooth surface formation and the stability of tool force, serving as a constant physical constraint limiting the upper limit of the entire machining system's dynamics. Based on this benchmark, the rotational angular velocity and spindle speed are synchronously controlled using the electronic gearbox or cross-coupling control algorithm of the underlying CNC system, ensuring that the workpiece's rotational frequency and the tool's high-frequency rotation maintain an absolute and strict theoretical speed ratio match at the cutting contact point. However, in real high-frequency multi-axis linkage machining scenarios, the actual response posture and speed of each physical axis of the machine tool often deviate slightly from the theoretical target set value due to the combined interference of multiple non-ideal physical factors such as sudden changes in dynamic cutting force, backlash lag in the mechanical transmission chain, and rigid deformation of the servo motor. Therefore, a high-frequency closed-loop sensor network configured at the ends of each feed and rotary axis of the machine tool is used for real-time status acquisition. Feedback values ​​are obtained for the following parameters: active deflection angle (characterizing the tool's anti-interference attitude in space), feed rate (characterizing the material removal efficiency of the cutting layer), spindle speed (characterizing the tool's cutting power output), and rotational angular velocity (characterizing the workpiece generating cycle). Through this underlying closed-loop operating mechanism of "reference constraint - synchronous drive - status perception," the rotational angular velocity and spindle speed are synchronously controlled based on a preset cutting linear velocity during interpolation control, and feedback values ​​for the active deflection angle, feed rate, spindle speed, and rotational angular velocity are obtained.

[0090] S105: Calculate the motion deviation between each feedback value and the corresponding target setting value, and perform dynamic compensation on the active deflection angle, feed rate, spindle speed and rotational angular velocity based on each motion deviation and the preset compensation control strategy. The target setting value includes the first target setting value, the second target setting value, the third target setting value and the fourth target setting value.

[0091] For example, the digital control core 301 captures the actual physical state of each motion axis in real time at an extremely high sampling frequency (e.g., millisecond level) and compares it with the planned theoretical trajectory at high speed. Assuming the theoretically planned active deflection angle (fourth target setpoint) is 15.500 degrees, while the actual feedback value collected by the grating ruler is 15.485 degrees, the digital control core 301 immediately calculates a motion deviation of 0.015 degrees. Subsequently, the digital control core 301 calls a preset compensation control strategy (e.g., PID closed-loop feedback adjustment for single-axis micro-position correction, cross-coupling synchronization control for multi-axis macro-motion synchronization, or state-space control law for comprehensive adjustment of the coupled dynamics of the entire system) to convert the absolute deviation into instantaneous fine-tuning increment commands for each servo axis and directly injects them into the speed loop and position loop at the bottom layer of the machine tool. This "real-time comparison-high-speed difference-instant correction" mechanism, based on a microscopic time scale, can quickly pull the actual spatial pose of the tool and the rotational speed of each axis back to the absolutely safe theoretically planned path in the instant that a slight mismatch in trajectory is caused by fluctuations in conventional cutting load or mechanical transmission clearance, thereby ensuring strict physical synchronization under high-frequency multi-axis linkage.

[0092] In one possible implementation, dynamic compensation is performed on the active deflection angle, feed rate, spindle speed, and rotational angular velocity based on various motion deviations and a preset compensation control strategy. Specifically, this includes: acquiring the spatial attitude matrix of the current interpolation cycle generated by the interpolation control, and determining the instantaneous angular velocity vector of each rotation axis in the rotary table and tool spindle system based on the feedback values ​​corresponding to the spindle speed, the feedback values ​​corresponding to the rotational angular velocity, and the spatial attitude matrix; calculating the gyroscopic effect compensation torque corresponding to each rotation axis based on the preset moment of inertia tensor and instantaneous angular velocity vector; converting each gyroscopic effect compensation torque into a corresponding kinematic compensation component based on the gyroscopic effect compensation torque and a preset stiffness coefficient, and superimposing the kinematic compensation component into the dynamic compensation performed on the active deflection angle, feed rate, spindle speed, and rotational angular velocity.

[0093] In this embodiment, the gyroscopic effect compensation torque refers to the amount of reverse cancellation of the unexpected precession torque induced by the high-speed rotation of the spindle and the worktable and their dynamic tilting in spatial orientation during five-axis linkage high-speed gear turning. It is used to represent the compensation torque reference that must be calculated and applied from the underlying dynamic level in order to maintain the absolute cutting trajectory of the tool in an extremely narrow inner hole. For example, when the tool spindle rotates at a speed within a first preset speed range (e.g., 3000 rpm) and simultaneously performs attitude interpolation fine-tuning at a second preset frequency range, the rotational inertia of the spindle rotor will generate a torque similar to the deflection of a gyroscope, causing the tool holder to produce micron-level elastic bending deformation. The gyroscopic effect compensation torque of, for example, 15 N·m, calculated at this time is a key dynamic parameter set to accurately quantify and cancel this physical deformation at the control level.

[0094] Specifically, when performing high-frequency interpolation on complex topology-modified meshes, the spatial attitude matrix of the current interpolation cycle generated by the interpolation control is first obtained. This matrix serves as a mathematical direction cosine operator describing the relative rotation and tilt directions of the tool and workpiece in three-dimensional microspace. Subsequently, based on the feedback values ​​corresponding to the spindle speed, the feedback values ​​corresponding to the rotational angular velocity, and the spatial attitude matrix, the pure scalar rotational velocity data is transformed into a spatial vector cross product and mapping with the spatial attitude matrix containing direction attributes. This allows for the precise deconstruction and determination of the instantaneous angular velocity vectors of each rotation axis in the rotary table and tool spindle system. ,in These are the instantaneous angular velocity components around the X, Y, and Z axes, comprehensively mapped to the tool's local coordinate system during multi-axis linkage. Furthermore, a preset rotational inertia tensor matrix reflecting the mass distribution characteristics of the machine tool's rotating components is retrieved. Combining Euler's dynamic equations, and based on a pre-defined coupling calculation between the moment of inertia tensor and the instantaneous angular velocity vector, the dynamic calculation expression is as follows:

[0095]

[0096] The additional dynamic disturbances generated by high-speed rotation and high-frequency oscillation are isolated, allowing for the calculation of the gyroscopic compensation torque for each rotation axis. However, CNC low-level commands cannot directly output "torque" to correct geometric position deviations. Therefore, physical parameters characterizing the mechanical resistance to deformation of each axis of the machine tool are introduced, based on the gyroscopic effect to compensate for torque and a preset stiffness coefficient matrix. By inversely mapping force and displacement using Hooke's law, the gyroscopic effect compensation torques are transformed into corresponding kinematic compensation components. This mapping equation is expressed as: This achieves a leap in physical dimensions from the dynamic "force" domain to the kinematic "displacement / angle" domain. Finally, the kinematic compensation components... The correction offsets of each feed axis and rotary axis are superimposed on the dynamic compensation performed on the active deflection angle, feed rate, spindle speed, and rotary angular velocity, and injected into the control loop as feedforward adjustment. It should be noted that the dynamic compensation here consists of two layers of compensation mechanisms: the first layer is a closed-loop feedback compensation based on motion deviation, which corrects the deviation between the target setpoint and the feedback value of each axis in real time, and is used to eliminate motion trajectory tracking errors caused by sudden changes in cutting force, transmission backlash, etc.; the second layer is a kinematic feedforward compensation based on gyroscopic effect to compensate for torque, which pre-calculates the dynamic disturbance based on the instantaneous angular velocity vector and moment of inertia tensor of each rotary axis and applies it in advance, in order to counteract the rectangular deformation of the precession force induced by the coupling of high-speed rotation and attitude sway. The two compensation layers work together in the control loop in a composite architecture of "feedforward + feedback". The feedforward layer actively cancels the foreseeable dynamic disturbances before the deviation occurs, and the feedback layer corrects the residual error in real time after the deviation occurs. In the end, dynamic compensation is performed on the active deflection angle, feed rate, spindle speed and rotational angular velocity based on each motion deviation and the preset compensation control strategy.

[0097] S106: Based on the active deflection angle, feed rate, spindle speed and rotational angular velocity after dynamic compensation, the tool spindle system and the rotary table are linked to enable the gear cutting cutter to continuously cut the internal spline gear workpiece.

[0098] For example, the digital control core 301 converts the target set values ​​of each dimension after feedforward correction and real-time dynamic compensation into high-frequency low-level servo drive commands. In the physical machining environment, the gear cutting tool maintains high-speed rotation under the drive of the tool spindle, while the rotary table drives the internal spline gear workpiece to rotate synchronously according to the strict generating theoretical speed ratio. The relative motion of the two forms a precise cutting speed field at the microscopic contact point. Since the tool spatial posture (active deflection angle) and feed rate (feed speed and rotation speed of each axis) have been offset in real time from the dynamic deformation and mechanical error caused by high-speed linkage, the gear cutting tool can remove the metal residue in the extremely restricted internal spline cavity with a stable and continuous feed state along the predetermined helical feed trajectory. This multi-axis linkage after full-dimensional dynamic correction ensures that the tool cutting edge always cuts into the material with a relative cutting angle close to the theoretical set value, and finally stably and accurately generates the internal spline tooth surface that meets the design expectations, forming an execution closed loop from kinematic compensation algorithm to solid material removal.

[0099] In one possible implementation, the tool spindle system is controlled to link with the rotary table, enabling the gear cutter to continuously cut the internal spline gear workpiece. Specifically, this includes: acquiring the actual feedback value of the cutting linear velocity, the feedback value corresponding to the feed rate, and the preset radial depth of cut in each machining pass of the continuous cutting; acquiring the current spindle load current feedback value of the current tool spindle system; using the spindle load current feedback value as a characterization parameter of the tool edge state; inputting the actual feedback value of the cutting linear velocity, the feedback value corresponding to the feed rate, the radial depth of cut, and the spindle load current feedback value into a preset surface roughness prediction model to obtain a predicted surface roughness value for the current machining pass; when the predicted surface roughness value is greater than a preset roughness threshold, generating a fine-tuning compensation command for the axial reference surface, the fine-tuning compensation command including a preset step offset along the axial direction of the internal spline gear workpiece; and performing axial step offset compensation on the tool spindle system and the rotary table in the next machining pass based on the fine-tuning compensation command.

[0100] In this embodiment, the surface roughness prediction model refers to a data-driven and physical mechanism joint algorithm architecture that integrates multi-dimensional kinematic machining parameters and underlying physical and electronic control signals. It is used to represent the feedforward quantitative mapping relationship between the current comprehensive cutting physical parameters and the final micro-unevenness of the internal spline gear tooth surface under unknown tool wear conditions and complex spatial multi-axis linkage conditions. For example, this model can be trained using a large amount of pre-collected gear cutting experimental data combined with machine learning algorithms (such as support vector machines or deep neural networks). When the current linear velocity, feed rate, depth of cut, and current ampere value reflecting changes in tool resistance are input, the model can output a predicted value such as Ra1.6 in real time, thereby transforming the physical surface quality, which is difficult to measure directly with probes during machining, into a data indicator that can be monitored in real time by the underlying control algorithm.

[0101] Specifically, within each machining pass of a continuous cutting process that divides the features to be processed into multiple layers of removal depth, in order to overcome the quality fluctuations caused by traditional "blind cutting" with fixed parameters, the actual feedback values ​​of the cutting linear velocity describing the current kinematic and geometric cutting boundaries, the feedback value corresponding to the feed rate, and the radial depth of cut characterizing the material removal thickness in a single pass are first acquired simultaneously. Meanwhile, since the cutting edge of the gear cutting tool inevitably undergoes microscopic wear and dulling during high-speed, high-frequency cutting, this physical degradation directly leads to increased cutting resistance and increases the drive torque and power consumption of the spindle motor. Therefore, the current spindle load current feedback value of the tool spindle system is acquired in real time. This built-in electrical parameter is used as a characterizing parameter implicitly reflecting the state of the tool cutting edge. Subsequently, the captured actual feedback values ​​of the cutting linear velocity are... Feedback value corresponding to feed rate Radial depth of cut Feedback value of spindle load current Perform normalization and arrangement to construct process feature vectors in the real number field. and the feature vector The surface roughness prediction model is synchronously input into the preset model, and the prediction mapping function is used. Perform nonlinear feature mapping on multi-source heterogeneous data, where A nonlinear regression mapping operator, generated through machine learning training and solidification within the surface roughness prediction model, analyzes the microscopic tooth surface morphology resulting from the combined effects of the current physical cutting boundary, thus obtaining a predicted surface roughness value for the current machining pass. Then, this predicted quality is monitored in real-time during the pass intervals. When the predicted surface roughness value is assessed to be greater than a preset roughness threshold (i.e., the predicted tooth surface produced in the current pass cannot meet the quality standards), in order to suppress the cumulative effect of microscopic morphology deterioration across passes, the control logic is triggered to generate a fine-tuning compensation command for the axial reference surface. This fine-tuning compensation command includes a preset step offset along the axial direction of the internal spline gear workpiece, aiming to allow the unworn microscopic area of ​​the cutting edge to participate in subsequent cutting by fine-tuning the axial entry point of the tool, or to smooth out residual peaks from previous machining using the principle of misaligned cutting. Finally, based on the fine-tuning compensation instruction, axial step compensation is performed on the tool spindle system and the rotary table in the next machining pass. Through this adaptive fine-tuning mechanism based on physical feedback and quality prediction, the tool spindle system and the rotary table are ultimately controlled to work together, so that the gear cutting cutter can continuously cut the internal spline gear workpiece.

[0102] In one possible implementation, after performing axial step compensation on the tool spindle system and rotary table in the next machining pass according to the fine-tuning compensation command, the process further includes: extracting the measured surface roughness values ​​of a consecutive preset number of teeth after axial step compensation through a preset on-machine measurement unit; comparing each measured surface roughness value with a preset roughness threshold; and stopping the generation of the fine-tuning compensation command when all measured surface roughness values ​​are less than or equal to the preset roughness threshold.

[0103] In this embodiment, the in-machine measurement unit refers to high-precision contact or non-contact detection hardware integrated and installed inside the machining area of ​​a five-axis CNC machine tool. It represents a means of verifying the physical detection and quantitative analysis of the microscopic geometry of the machined tooth surface directly in situ without disrupting the single-setup positioning reference. For example, this unit can be a trigger-type micrometer probe automatically picked up by the machine tool magazine, or an optical laser confocal scanner with nanometer-level resolution. It can immediately extend into the confined cavity of the internal spline gear after the compensation cutting pass ends to acquire the actual surface roughness physical data, thereby providing closed-loop truth verification for the feedforward prediction model.

[0104] Specifically, after completing the dynamic fine-tuning action initiated based on feedforward prediction of quality deterioration—that is, after performing axial step compensation on the tool spindle system and rotary table in the next machining pass according to the fine-tuning compensation command—an in-situ physical inspection process is automatically triggered to verify whether the step offset has effectively pulled the tooth surface quality back to the acceptable range. First, the spindle is driven to position itself in the internal hole machining area. Using a preset on-machine measurement unit, a high-precision morphological scan is performed on the specific tooth surface that has just undergone step compensation cutting. To eliminate interference from single-point random errors caused by uneven local material hardness or residual chips, statistically significant array data needs to be obtained across multiple tooth pitches. Then, the measured surface roughness values ​​of a consecutive preset number of teeth after axial step compensation are extracted. Subsequently, the acceptable boundary conditions strictly defined in the process standard library for this internal spline gear drawing are retrieved, and each measured surface roughness value is rigorously logically judged and compared with a preset roughness threshold. After a full comparison and evaluation, if it is confirmed that all sampled physical data have fallen back to a safe process quality range, that is, when the measured surface roughness values ​​are all less than or equal to the preset roughness threshold, it means that the unworn cutting edge of the current tool and the new axial infeed origin have reached a new steady-state cutting balance. At this time, in order to avoid continuous meaningless offset leading to excessive consumption of machining allowance or causing new spatial interference, the closed-loop adjustment intervention logic is actively cut off, thereby stopping the generation of fine-tuning compensation commands. Conversely, when the cumulative number of continuously generated fine-tuning compensation commands reaches the preset maximum compensation number threshold, and the measured surface roughness values ​​are still greater than the preset roughness threshold, it indicates that the wear degree of the current tool cutting edge has exceeded the compensable range. At this time, the generation of fine-tuning compensation commands is stopped and a tool replacement alarm signal is output to avoid irreversible deterioration of tooth surface quality caused by continuing to process under excessive tool wear.

[0105] Figure 2 This is a schematic diagram of a system for machining internal splined gears according to an embodiment of this application. This system can be implemented through software, hardware, or a combination of both, forming all or part of the overall system. For example... Figure 2 As shown, the system includes:

[0106] The trajectory planning module 201 is used to obtain the theoretical tooth profile parameters and tooth surface modification parameters of the internal spline gear workpiece, construct a parameterized tooth surface topology modification model based on the theoretical tooth profile parameters and tooth surface modification parameters, and analyze the parameterized tooth surface topology modification model through a preset kinematic solution algorithm to generate a helical feed trajectory of the turning cutter coupled with the axial and circumferential motion along the internal spline gear workpiece.

[0107] The parameter setting module 202 is used to determine the preset cutting line speed based on the helical feed trajectory, and obtain the first target setting value of the feed speed corresponding to the helical feed trajectory. Based on the preset cutting line speed, it determines the second target setting value of the spindle speed of the tool spindle system and the third target setting value of the rotational angular velocity of the rotary table.

[0108] The attitude calculation module 203 is used to calculate the fourth target setting value of the active deflection angle of the cutting tool axis of the gear cutting tool relative to the workpiece axis of the internal spline gear workpiece based on the preset kinematic constraint equation, the first target setting value, the second target setting value, and the third target setting value.

[0109] The status acquisition module 204 is used to synchronously control the rotational angular velocity and spindle speed based on the preset cutting line speed during the interpolation control process, and to acquire the feedback values ​​corresponding to the active deflection angle, feed rate, spindle speed and rotational angular velocity respectively.

[0110] The dynamic compensation module 205 is used to calculate the motion deviation between each feedback value and the corresponding target setting value, and to perform dynamic compensation on the active deflection angle, feed speed, spindle speed and rotational angular velocity based on each motion deviation and the preset compensation control strategy. The target setting value includes a first target setting value, a second target setting value, a third target setting value and a fourth target setting value.

[0111] The linkage cutting module 206 is used to control the linkage between the tool spindle system and the rotary table based on the dynamically compensated active deflection angle, feed rate, spindle speed and rotational angular velocity, so that the gear cutting cutter can continuously cut the internal spline gear workpiece.

[0112] Based on the above embodiments, as an optional embodiment, the trajectory planning module 201 is specifically used for: constructing a reference theoretical tooth surface equation based on theoretical tooth profile parameters; obtaining preset tooth profile convexity, tooth bulging, tooth tip chamfer radius, and tooth root transition radius in the tooth surface modification parameters; constructing a multi-modality modification parameter matrix based on the tooth profile convexity, tooth bulging, tooth tip chamfer radius, and tooth root transition radius; substituting the multi-modality modification parameter matrix into a preset tooth surface deviation function to calculate the spatial deviation compensation mesh; and superimposing the spatial deviation compensation mesh onto the reference theoretical tooth surface equation to generate a parameterized tooth surface topology modification model.

[0113] Based on the above embodiments, as an optional embodiment, the trajectory planning module 201 is specifically used to: perform parameterized resampling on the helical feed trajectory to generate a kinematic sequence containing position attributes, velocity attributes, acceleration attributes, and jerk attributes; extract each motion segment in the kinematic sequence and insert acceleration / deceleration transition segments in each motion segment; perform constraint processing on the kinematic sequence after inserting acceleration / deceleration transition segments based on a preset maximum jerk threshold to obtain a smooth reconstructed trajectory, and use the smooth reconstructed trajectory as the helical feed trajectory.

[0114] Based on the above embodiments, as an optional embodiment, the attitude calculation module 203 is specifically used to: obtain the average rotation radius of the cutting edge of the gear cutting tool and obtain the preset inner hole radius of the internal spline gear workpiece; determine the tool-side kinematic component including the tool space velocity vector based on the first target setting value, the second target setting value and the average rotation radius of the cutting edge; determine the workpiece-side kinematic component including the workpiece composite velocity vector based on the third target setting value, the preset inner hole radius and the first target setting value; and perform a preset trigonometric function mapping analysis based on the tool-side kinematic component and the workpiece-side kinematic component to obtain the fourth target setting value of the active deflection angle.

[0115] Based on the above embodiments, as an optional embodiment, the dynamic compensation module 205 is specifically used to: obtain the spatial attitude matrix of the current interpolation cycle generated by the interpolation control, and determine the instantaneous angular velocity vector of each rotating axis in the rotary table and tool spindle system according to the feedback value corresponding to the spindle speed, the feedback value corresponding to the rotational angular velocity, and the spatial attitude matrix; calculate the gyroscopic effect compensation torque corresponding to each rotating axis based on the preset moment of inertia tensor and instantaneous angular velocity vector; convert each gyroscopic effect compensation torque into a corresponding kinematic compensation component based on the gyroscopic effect compensation torque and the preset stiffness coefficient, and superimpose the kinematic compensation component into the dynamic compensation performed on the active deflection angle, feed speed, spindle speed, and rotational angular velocity.

[0116] Based on the above embodiments, as an optional embodiment, the linkage cutting module 206 is specifically used to: obtain the actual feedback value of the cutting linear velocity, the feedback value corresponding to the feed rate, and the preset radial depth of cut in each machining pass of continuous cutting, and obtain the spindle load current feedback value of the current tool spindle system, and use the spindle load current feedback value as a characterization parameter of the tool cutting edge state; input the actual feedback value of the cutting linear velocity, the feedback value corresponding to the feed rate, the radial depth of cut, and the spindle load current feedback value into a preset surface roughness prediction model to obtain the surface roughness prediction value for the current machining pass; when the surface roughness prediction value is greater than the preset roughness threshold, generate a fine-tuning compensation command for the axial reference surface, the fine-tuning compensation command includes a preset step offset along the axial direction of the internal spline gear workpiece, and perform axial step compensation on the tool spindle system and the rotary table in the next machining pass according to the fine-tuning compensation command.

[0117] Based on the above embodiments, as an optional embodiment, the linkage cutting module 206 is specifically used to: extract the measured surface roughness values ​​of a continuous preset number of teeth after axial step compensation through a preset on-machine measurement unit; compare each measured surface roughness value with a preset roughness threshold; and stop generating fine-tuning compensation commands when each measured surface roughness value is less than or equal to the preset roughness threshold.

[0118] It should be noted that in the system for turning internal spline gears provided in this application, the above-mentioned functional modules do not operate in isolation, but rather rely on the real-time operating system at the bottom of the CNC system to build a rigorous data flow mechanism. For example, after resampling the parameterized tooth surface topology model at the non-real-time task layer, the trajectory planning module 201 writes the smoothed reconstructed trajectory data into the shared memory area of ​​the CNC system. The parameter setting module 202 and the attitude calculation module 203 then read the trajectory data from the shared memory area and complete the kinematic mapping calculation of the velocity vector and the active deflection angle during the interpolation preprocessing stage, generating a low-level control instruction set containing multi-axis linkage timing. When entering the high-frequency interpolation cycle, the status acquisition module 204 captures the position and current feedback values ​​of each servo drive in real time at a microsecond cycle through the machine tool fieldbus (such as EtherCAT or PROFINET). The dynamic compensation module 205 runs in the highest priority real-time interrupt task, completes the physical dimension decoupling calculation of gyro effect and motion deviation within the current interrupt cycle after receiving the feedback value, and directly superimposes the final kinematic compensation component into the drive command of the linkage cutting module 206 and sends it to the physical axis. Through the interaction of the above-mentioned layered architecture and real-time data bus, the data synchronization and coordination between complex microscopic spatial pose calculation and the high-speed closed-loop execution of the low-level servo is ensured.

[0119] This embodiment also discloses an electronic device applied to a five-axis CNC machine tool, referring to... Figure 3 The electronic device may include: at least one digital control core 301, at least one communication bus 302, human-machine interface 303, industrial fieldbus interface 304, at least one memory 305, and programmable logic controller 306.

[0120] The communication bus 302 is used to enable communication between these components.

[0121] The human-machine interface 303 may include a display screen and an operation panel for displaying processing status and receiving operation commands.

[0122] The industrial fieldbus interface 304 is used to communicate with multi-axis servo drive units via industrial fieldbuses (such as EtherCAT, PROFINET, or CANopen).

[0123] Specifically, in the industrial scenario of applying this application to a five-axis CNC machine tool, the aforementioned digital control core 301 can be concretized as the digital control kernel (NCK) of a computer numerical control (CNC) system. It is specifically responsible for handling complex floating-point operations, including high-frequency analysis of the parametric tooth surface topology model, spatial trigonometric function mapping, and dynamic feedforward compensation calculations including gyroscopic torque, ensuring nanosecond-level instruction interpolation cycles. The aforementioned programmable logic controller 306 is responsible for handling the logical action control of the machine tool, such as controlling the probe extension and retraction of the on-machine measurement unit, the clamping action of the spindle fixture, and the start and stop of the cutting fluid. The digital control core 301 and the programmable logic controller 306 interact via a communication bus 302.

[0124] Furthermore, the electronic device also includes a multi-axis servo drive unit that is connected to the industrial fieldbus interface 304 via a high-speed industrial fieldbus. The digital control core 301 calculates and superimposes dynamic compensation values ​​for position and speed loop commands such as active deflection angle, feed rate, spindle speed, and rotational angular velocity, and sends them to the multi-axis servo drive unit via the industrial fieldbus interface 304. The power amplifier module inside the servo drive unit converts the aforementioned low-voltage digital signals into high-power three-phase AC power, thereby driving the electric spindle in the tool spindle system and the direct-drive torque motor in the rotary table to achieve rigid cutting motion in physical space.

[0125] The memory 305 may include random access memory (RAM) or read-only memory. Optionally, the memory 305 may include a non-transitory computer-readable storage medium. The memory 305 can be used to store instructions, programs, code, code sets, or instruction sets. The memory 305 may include a program storage area and a data storage area, wherein the program storage area may store instructions for implementing a real-time operating system, instructions for motion control functions, instructions for implementing the above-described method embodiments, etc.; the data storage area may store processing parameter data involved in the above-described method embodiments, etc. Optionally, the memory 305 may also be at least one storage device located remotely from the aforementioned digital control core 301. Figure 3 As shown, the memory 305, which serves as a computer storage medium, may include a real-time operating system, a motion control program, a machining parameter database, and an application program for a method of turning internal spline gears.

[0126] exist Figure 3 In the electronic device shown, the human-machine interface 303 is mainly used to provide the operator with an interface for displaying the processing status and inputting operation instructions, and to obtain the processing parameters and operation instructions input by the operator; while the digital control core 301 can be used to call an application program of a method for turning internal spline gears stored in the memory 305. When executed by one or more digital control cores 301, the electronic device executes one or more methods as described in the above embodiments.

[0127] It should be noted that, for the sake of simplicity, the foregoing method embodiments are all described as a series of actions. However, those skilled in the art should understand that this application is not limited to the described order of actions, as some steps may be performed in other orders or simultaneously according to this application. Furthermore, those skilled in the art should also understand that the embodiments described in the specification are preferred embodiments, and the actions and modules involved are not necessarily essential to this application.

[0128] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0129] In the several embodiments provided in this application, it should be understood that the disclosed apparatus can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the shown or discussed mutual couplings or direct couplings or communication connections may be through some service interfaces; indirect couplings or communication connections between apparatuses or units may be electrical or other forms.

[0130] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0131] Furthermore, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0132] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage device (CMD). Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a memory 305 and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods of the various embodiments of this application. The aforementioned memory 305 includes various media capable of storing program code, such as a USB flash drive, external hard drive, magnetic disk, or optical disk.

[0133] The above description is merely an exemplary embodiment of this application and should not be construed as limiting the scope of this application. Any equivalent changes and modifications made in accordance with the teachings of this application shall still fall within the scope of this application. Those skilled in the art will readily conceive of other embodiments of this application upon considering the disclosure of this specification. This application is intended to cover any variations, uses, or adaptations of this application that follow the general principles of this application and include common knowledge or customary techniques in the art not described in this application. The specification and embodiments are considered exemplary only, and the scope of disclosure of this application is defined by the claims.

Claims

1. A method for turning internal splined gears, applied to a five-axis CNC machine tool, the five-axis CNC machine tool comprising a rotary table and a tool spindle system, wherein the rotary table and the tool spindle system each have at least one rotational degree of freedom, characterized in that... The internal spline gear workpiece to be machined is clamped on the rotary worktable, and the gear cutting cutter is mounted on the tool spindle system. The method includes: The theoretical tooth profile parameters and tooth surface modification parameters of the internal spline gear workpiece are obtained. A parameterized tooth surface topology modification model is constructed based on the theoretical tooth profile parameters and the tooth surface modification parameters. The parameterized tooth surface topology modification model is analyzed by a preset kinematic solution algorithm to generate a helical feed trajectory of the turning cutter along the axial and circumferential coupled motion of the internal spline gear workpiece. Based on the helical feed trajectory, a preset cutting line speed is obtained, and a first target setting value of the feed speed corresponding to the helical feed trajectory is obtained. Based on the preset cutting line speed, a second target setting value of the spindle speed of the tool spindle system and a third target setting value of the rotational angular velocity of the rotary table are determined. Based on the preset kinematic constraint equations, and based on the first target setting value, the second target setting value, and the third target setting value, a fourth target setting value is calculated for the active deflection angle of the cutting tool axis relative to the workpiece axis of the internal spline gear workpiece. During the interpolation control process, the preset cutting line speed is used as a reference, and the rotational angular velocity and the spindle speed are controlled synchronously. The feedback values ​​corresponding to the active deflection angle, the feed rate, the spindle speed and the rotational angular velocity are obtained respectively. Calculate the motion deviation between each of the feedback values ​​and the corresponding target set value, and perform dynamic compensation on the active deflection angle, the feed rate, the spindle speed and the rotational angular velocity based on each of the motion deviations and the preset compensation control strategy. The target set value includes the first target set value, the second target set value, the third target set value and the fourth target set value. Based on the dynamically compensated active deflection angle, feed rate, spindle speed, and rotational angular velocity, the tool spindle system is controlled to work in conjunction with the rotary table, so that the gear cutting cutter can continuously cut the internal spline gear workpiece.

2. The method according to claim 1, characterized in that, The construction of a parametric tooth surface topology modification model based on the theoretical tooth profile parameters and the tooth surface modification parameters specifically includes: Based on the theoretical tooth profile parameters, a reference theoretical tooth surface equation is constructed; Obtain the preset tooth profile convexity, tooth bulge, tooth tip chamfer radius, and tooth root transition radius from the tooth surface modification parameters; Based on the tooth profile convexity, tooth bulging, tooth tip chamfer radius, and tooth root transition radius, a multi-maintenance profile parameter matrix is ​​constructed. Substituting the multi-maintenance profile parameter matrix into the preset tooth surface deviation function, the spatial deviation compensation mesh is calculated; The spatial deviation compensation mesh is superimposed onto the reference theoretical tooth surface equation to generate the parameterized tooth surface topology modification model.

3. The method according to claim 1, characterized in that, After generating the helical feed trajectory of the turning cutter coupled axially and circumferentially along the internal spline gear workpiece, and before obtaining the preset cutting speed based on the helical feed trajectory, the method further includes: The spiral feed trajectory is parametrically resampled to generate a kinematic sequence containing position, velocity, acceleration, and jerk attributes. Extract each motion segment from the kinematic sequence and insert acceleration / deceleration transition segments into each motion segment; Based on a preset maximum acceleration threshold, constraint processing is performed on the kinematic sequence after the acceleration / deceleration transition section to obtain a smooth reconstructed trajectory, and the smooth reconstructed trajectory is used as the helical feed trajectory.

4. The method according to claim 1, characterized in that, The step of calculating a fourth target setting value—the active deflection angle of the cutting tool axis relative to the workpiece axis of the internal spline gear workpiece—based on the preset kinematic constraint equations, the first target setting value, the second target setting value, and the third target setting value, specifically includes: Obtain the average turning radius of the cutting edge of the gear cutting tool, and obtain the preset inner hole radius of the internal spline gear workpiece; Based on the first target setting value, the second target setting value and the average turning radius of the cutting edge, the tool side kinematic components including the tool space velocity vector are determined; Based on the third target setting value, the preset inner hole radius, and the first target setting value, determine the workpiece side kinematic components that include the workpiece composite velocity vector; Based on the tool-side kinematic components and the workpiece-side kinematic components, a preset trigonometric function mapping analysis is performed to obtain the fourth target setting value of the active deflection angle.

5. The method according to claim 1, characterized in that, The dynamic compensation for the active deflection angle, the feed rate, the spindle speed, and the rotational angular velocity, based on the motion deviations and a preset compensation control strategy, specifically includes: Obtain the spatial attitude matrix of the current interpolation cycle generated by the interpolation control, and determine the instantaneous angular velocity vectors of each rotation axis in the rotary table and the tool spindle system based on the feedback value corresponding to the spindle speed, the feedback value corresponding to the rotational angular velocity, and the spatial attitude matrix. Based on the preset moment of inertia tensor and the instantaneous angular velocity vector, the gyroscopic effect compensation torque corresponding to each of the rotation axes is calculated; Based on the gyroscopic effect compensation torque and the preset stiffness coefficient, each of the gyroscopic effect compensation torques is converted into a corresponding kinematic compensation component, and the kinematic compensation component is superimposed on the dynamic compensation performed on the active deflection angle, the feed rate, the spindle speed and the rotational angular velocity.

6. The method according to claim 1, characterized in that, The control of the tool spindle system in conjunction with the rotary table, enabling the gear cutting cutter to continuously cut the internal spline gear workpiece, specifically includes: In each machining pass of continuous cutting, the actual feedback value of the cutting line speed, the feedback value corresponding to the feed speed and the preset radial depth of cut are obtained, and the current spindle load current feedback value of the tool spindle system is obtained. The spindle load current feedback value is used as a characterization parameter of the tool cutting edge state. The actual feedback value of the cutting line speed, the feedback value corresponding to the feed speed, the radial depth of cut and the spindle load current feedback value are input into a preset surface roughness prediction model to obtain the surface roughness prediction value for the current machining pass. When the predicted surface roughness value is greater than the preset roughness threshold, a fine-tuning compensation instruction is generated for the axial reference surface. The fine-tuning compensation instruction includes a preset step offset along the axial direction of the internal spline gear workpiece. Based on the fine-tuning compensation instruction, axial step compensation is performed on the tool spindle system and the rotary table in the next machining pass.

7. The method according to claim 6, characterized in that, After performing axial step compensation on the tool spindle system and the rotary table in the next machining pass according to the fine-tuning compensation command, the process further includes: The measured surface roughness value of a continuous preset number of teeth after the axial step compensation is performed is extracted by a preset in-machine measurement unit. Each of the measured surface roughness values ​​is compared with the preset roughness threshold. When all the measured surface roughness values ​​are less than or equal to the preset roughness threshold, the generation of the fine-tuning compensation command is stopped.

8. A system for turning internal splined gears, applied to a five-axis CNC machine tool, the five-axis CNC machine tool comprising a rotary table and a tool spindle system, the rotary table and the tool spindle system each having at least one rotational degree of freedom, characterized in that... The internal spline gear workpiece to be machined is clamped on the rotary worktable, and the gear cutting cutter is mounted on the tool spindle system, which includes: The trajectory planning module is used to obtain the theoretical tooth profile parameters and tooth surface modification parameters of the internal spline gear workpiece, construct a parameterized tooth surface topology modification model based on the theoretical tooth profile parameters and the tooth surface modification parameters, and analyze the parameterized tooth surface topology modification model through a preset kinematic solution algorithm to generate a helical feed trajectory of the turning cutter along the axial and circumferential coupled motion of the internal spline gear workpiece. The parameter setting module is used to obtain a preset cutting line speed based on the spiral feed trajectory, and obtain a first target setting value of the feed speed corresponding to the spiral feed trajectory. Based on the preset cutting line speed, it determines a second target setting value of the spindle speed of the tool spindle system and a third target setting value of the rotational angular velocity of the rotary table. The attitude calculation module is used to calculate a fourth target setting value based on the preset kinematic constraint equations, the first target setting value, the second target setting value, and the third target setting value, the active deflection angle of the cutting tool axis of the gear cutting tool relative to the workpiece axis of the internal spline gear workpiece. The status acquisition module is used to synchronously control the rotational angular velocity and the spindle speed based on the preset cutting line speed during the interpolation control process, and to acquire the feedback values ​​corresponding to the active deflection angle, the feed rate, the spindle speed and the rotational angular velocity respectively. The dynamic compensation module is used to calculate the motion deviation between each of the feedback values ​​and the corresponding target set value, and to perform dynamic compensation on the active deflection angle, the feed speed, the spindle speed and the rotational angular velocity based on each of the motion deviations and the preset compensation control strategy. The target set value includes the first target set value, the second target set value, the third target set value and the fourth target set value. The linkage cutting module is used to control the linkage between the tool spindle system and the rotary table based on the dynamically compensated active deflection angle, the feed rate, the spindle speed and the rotational angular velocity, so that the gear cutting cutter can continuously cut the internal spline gear workpiece.

9. An electronic device applied to a five-axis CNC machine tool, characterized in that, include: The digital control core is used to perform kinematic calculation and dynamic compensation calculation in the method described in any one of claims 1-7, and to send the compensated control commands to the multi-axis servo drive unit through the industrial fieldbus interface to drive the physical cutting action. A programmable logic controller (PLC) is used to execute the logical motion control of the five-axis CNC machine tool. The memory is used to store instructions and processing parameter data; The human-machine interface is used to display the processing status and receive operation commands; the industrial fieldbus interface is used to communicate with the multi-axis servo drive unit.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores instructions that, when executed, perform the method as described in any one of claims 1-7.

Images