Five-axis machining center tool wear online monitoring compensation system and method thereof

Abstract

The application discloses a kind of five-axis machining center tool wear online monitoring compensation systems, including five-axis machining center body, the five-axis machining center body includes X axis, Y axis, Z axis three linear axes and A axis, C axis two rotary axes, and chucking on rotary axis main shaft, the main shaft is clamped with tool, further include data acquisition module, wear monitoring module, compensation calculation module and execution compensation module;The data acquisition module is correspondingly arranged with main shaft or tool, and the state data in the process of tool processing is collected;The wear monitoring module is connected with data acquisition module, and the feature extraction is carried out to state data.The application compared with prior art has the advantages that: provide a kind of five-axis machining center tool wear online monitoring compensation system and its method, which can realize the real-time acquisition of tool processing state data, the intelligent extraction of wear feature and the real-time mapping generation of compensation value calculation, compensation value.

Description

Technical Field

[0001] This invention relates to the field of CNC machining technology, specifically to an online monitoring and compensation system and method for tool wear in a five-axis machining center. Background Technology

[0002] Five-axis machining centers are widely used in aerospace, mold manufacturing, and medical device industries because they can achieve efficient and precise machining of complex curved surface parts.

[0003] However, during five-axis machining, the relative posture between the tool and the workpiece changes continuously, the cutting load is complex and variable, the tool wear rate is fast and the wear pattern is diverse, which seriously affects the machining accuracy and surface quality.

[0004] Existing tool management mainly relies on timed replacement or offline inspection. Offline inspection requires stopping the machine to disassemble the tool, which has a long inspection cycle and cannot reflect the true wear status of the tool during the machining process in a timely manner. This may result in the use of severely worn tools to continue machining between two inspections, causing parts to be out of tolerance or even scrapped.

[0005] Existing online monitoring systems are mostly designed for three-axis machining scenarios, lacking effective analytical methods for the coupling characteristics of cutting forces, vibrations, and acoustic emission signals caused by dynamic changes in tool posture during five-axis linkage machining, resulting in low wear identification accuracy.

[0006] Therefore, there is an urgent need for a monitoring and compensation system that can realize real-time monitoring of tool wear status, accurate calculation of wear amount, and online writing and execution of compensation value during five-axis machining. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to overcome the above-mentioned technical defects and provide a five-axis machining center tool wear online monitoring and compensation system and method that can realize real-time acquisition of tool processing status data, intelligent extraction of wear characteristics and calculation of wear amount, and real-time mapping and generation of compensation value.

[0008] To solve the above-mentioned technical problems, the technical solution provided by the present invention is as follows: a five-axis machining center tool wear online monitoring and compensation system, including a five-axis machining center body, the five-axis machining center body including three linear axes (X-axis, Y-axis, and Z-axis) and two rotary axes (A-axis and C-axis), and a spindle clamped on the rotary axes, the spindle clamping a tool, and also including a data acquisition module, a wear monitoring module, a compensation calculation module and an execution compensation module;

[0009] The data acquisition module is set up corresponding to the spindle or tool to collect status data during the tool machining process;

[0010] The wear monitoring module is connected to the data acquisition module, which extracts features from the status data, obtains tool wear feature parameters, and calculates the tool wear amount based on the tool wear feature parameters.

[0011] The compensation calculation module is connected to the wear monitoring module and calculates the tool compensation value based on the tool wear. The execution compensation module is connected to the compensation calculation module and the CNC system of the five-axis machining center body, and inputs the tool compensation value into the CNC system to perform online compensation for the tool trajectory and tool offset.

[0012] Preferably, the status data includes at least one of cutting force signal, vibration signal, spindle current signal, and acoustic emission signal.

[0013] Preferably, the data acquisition module includes at least one of a force sensor, an acceleration sensor, a current sensor, and an acoustic emission sensor;

[0014] The force sensor is located on the spindle bearing housing, the acceleration sensor is located on the spindle, the current sensor is connected in series with the spindle drive circuit, and the acoustic emission sensor is located on the spindle.

[0015] Preferably, the wear monitoring module includes a signal preprocessing unit and a wear identification unit;

[0016] The signal preprocessing unit performs filtering and noise reduction on the state data and extracts time-frequency domain features to obtain tool wear feature parameters.

[0017] The wear identification unit calculates the tool wear amount based on the tool wear characteristic parameters.

[0018] Preferably, the compensation calculation module includes a tool geometry compensation unit and a trajectory compensation unit;

[0019] The tool geometry compensation unit corrects the tool radius compensation value and the tool length compensation value according to the tool wear amount;

[0020] The trajectory compensation unit corrects the five-axis linkage machining trajectory based on the tool wear.

[0021] Preferably, the execution compensation module includes a communication interface unit, which communicates with the CNC system via either Ethernet or fieldbus to write the tool compensation value into the tool compensation register of the CNC system.

[0022] Another aspect of the present invention discloses an online monitoring and compensation method for tool wear in a five-axis machining center, comprising the following steps:

[0023] S1: Collect status data during the tool machining process through the data acquisition module;

[0024] S2: The wear monitoring module extracts features from the status data, obtains tool wear feature parameters, and calculates the tool wear amount based on the tool wear feature parameters;

[0025] S3: The compensation calculation module calculates the tool compensation value based on the tool wear amount;

[0026] S4: The execution compensation module inputs the tool compensation value into the CNC system to perform online compensation for the tool path and tool offset.

[0027] Preferably, step S2 includes filtering and denoising the state data and extracting time-frequency domain features to obtain tool wear feature parameters.

[0028] Preferably, S3 includes correcting the tool radius compensation value and tool length compensation value according to the tool wear amount, and correcting the five-axis linkage machining trajectory according to the tool wear amount.

[0029] The advantages of this invention compared with the prior art are as follows: This invention achieves real-time synchronous acquisition of multi-dimensional state data such as cutting force, vibration, current and acoustic emission by arranging force sensors, acceleration sensors, current sensors and acoustic emission sensors in the spindle bearing housing, spindle and drive circuit, thus overcoming the defects of long offline detection cycle and information lag.

[0030] In this invention, the data is filtered and denoised, and the time-frequency domain features are extracted. Combined with the wear identification model, the tool wear is calculated, which effectively analyzes the signal coupling characteristics in five-axis linkage machining and improves the wear identification accuracy.

[0031] In this invention, the wear amount is mapped in real time to the tool radius, length compensation value and five-axis linkage trajectory correction amount through the tool geometry compensation and trajectory compensation unit; it is directly written into the tool compensation register of the CNC system through the communication interface, realizing closed-loop online control of compensation monitoring, without the need for machine stoppage and manual intervention, which significantly improves the accuracy and efficiency of five-axis machining. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of an online tool wear monitoring and compensation system for a five-axis machining center.

[0033] Figure 2 This is a structural diagram of the data acquisition module.

[0034] Figure 3 This is a flowchart illustrating an online monitoring and compensation method for tool wear in a five-axis machining center. Detailed Implementation

[0035] The present invention will now be described in further detail with reference to the accompanying drawings.

[0036] Combined with appendix Figure 1-3As shown, a five-axis machining center tool wear online monitoring and compensation system includes a five-axis machining center body, which includes three linear axes (X-axis, Y-axis, and Z-axis) and two rotary axes (A-axis and C-axis), as well as a spindle clamped on the rotary axes.

[0037] The spindle is equipped with a cutting tool. It also includes a data acquisition module, a wear monitoring module, a compensation calculation module, and a compensation execution module. The data acquisition module is configured corresponding to the spindle or cutting tool to collect status data during the tool machining process. The wear monitoring module is connected to the data acquisition module, extracts features from the status data, obtains tool wear characteristic parameters, and calculates the tool wear amount based on these parameters.

[0038] The compensation calculation module is connected to the wear monitoring module and calculates the tool compensation value based on the tool wear. The execution compensation module is connected to the compensation calculation module and the CNC system of the five-axis machining center body, and inputs the tool compensation value into the CNC system to perform online compensation for the tool trajectory and tool offset.

[0039] The data acquisition module includes at least one of a force sensor, an acceleration sensor, a current sensor, and an acoustic emission sensor. The force sensor is located in the spindle bearing housing and is used to collect radial and axial cutting force signals on the spindle bearing during the cutting process, reflecting the mechanical load state between the tool and the workpiece. The acceleration sensor is located in the spindle housing or spindle end and is used to collect vibration signals of the spindle and the tool, capturing cutting chatter and abnormal vibration frequencies caused by tool wear.

[0040] The current sensor is connected in series with the spindle drive circuit to collect the spindle motor drive current signal. Current fluctuations can indirectly reflect changes in cutting load and tool wear. The acoustic emission sensor is located on the outer wall of the spindle near the tool end to collect high-frequency elastic wave signals generated by material fracture and friction during tool cutting. It is sensitive to tool chipping and microcracks. The above multiple sensors can be selected individually or in combination according to the machining conditions. For example, force sensors and current sensors are the main sensors during rough machining, while acoustic emission sensors are added during finish machining to monitor minute wear.

[0041] In one embodiment, the wear monitoring module includes a signal preprocessing unit and a wear identification unit. The signal preprocessing unit performs filtering and noise reduction on the state data and extracts time-frequency domain features to obtain tool wear feature parameters. Specifically, the filtering and noise reduction uses wavelet thresholding or empirical mode decomposition to remove environmental noise and harmonic interference.

[0042] Time-frequency domain feature extraction includes extracting the mean and variance of the cutting force signal, the peak frequency and frequency band energy ratio of the vibration signal, the harmonic distortion rate of the current signal, and the root mean square value and impact count of the acoustic emission signal. These feature parameters are strongly correlated with the wear amount of the tool flank.

[0043] The wear identification unit calculates the tool wear amount based on the tool wear feature parameters. It can use a regression model based on support vector machine, random forest or deep neural network to map the multidimensional feature parameters into the tool flank wear amount value.

[0044] The compensation calculation module includes a tool geometry compensation unit and a trajectory compensation unit. The tool geometry compensation unit corrects the tool radius compensation value and the tool length compensation value according to the tool wear amount. For example, when the detected tool wear amount in the radial direction is 0.02 mm, the tool radius compensation value of the CNC system is updated to the original compensation value minus 0.02 mm.

[0045] When wear in the tool length direction is detected, causing axial dimension deviation, the tool length compensation value is corrected accordingly. The trajectory compensation unit corrects the five-axis linkage machining trajectory based on the tool wear amount. For the tool tip offset caused by the change in tool attitude angle during five-axis machining, the actual position deviation of the tool tip in the workpiece coordinate system is calculated by combining the rotation angles of the A-axis and C-axis, and the corrected tool position coordinates are generated to ensure the machining accuracy of complex curved surfaces.

[0046] The compensation module includes a communication interface unit, which communicates with the CNC system via either Ethernet or fieldbus to write the tool compensation value into the tool compensation register of the CNC system.

[0047] Ethernet communication is suitable for open CNC systems that support OPC UA or MTConnect protocols, enabling high-speed data transmission and remote monitoring;

[0048] Fieldbus systems such as PROFIBUS or EtherCAT are suitable for closed-loop compensation scenarios with high real-time requirements. After the compensation value is written, the CNC system automatically calls the updated tool compensation parameters in subsequent interpolation calculations to achieve online real-time compensation of tool path and tool offset.

[0049] In a specific implementation, this invention discloses an online monitoring and compensation method for tool wear in a five-axis machining center, comprising the following steps:

[0050] S1: Collect status data during the tool machining process through the data acquisition module;

[0051] S2: The wear monitoring module extracts features from the status data, obtains tool wear feature parameters, and calculates the tool wear amount based on the tool wear feature parameters;

[0052] S3: The compensation calculation module calculates the tool compensation value based on the tool wear amount;

[0053] S4: The execution compensation module inputs the tool compensation value into the CNC system to perform online compensation for the tool path and tool offset.

[0054] In one embodiment: S2 includes filtering and denoising the state data and extracting time-frequency domain features to obtain tool wear feature parameters. For example, after performing wavelet denoising on the cutting force signal, the average cutting force and fluctuation amplitude in the time domain are extracted, as well as the proportion of feature frequency energy related to tool wear in the frequency domain, and a multi-dimensional feature vector is input into the wear recognition model.

[0055] In one embodiment: S3 includes correcting the tool radius compensation value and tool length compensation value according to the tool wear amount, and correcting the five-axis linkage machining trajectory according to the tool wear amount. For example, in the machining of a five-axis impeller, when the tool ball head radius decreases due to wear, not only is the tool radius compensation value updated, but the actual position of the tool tip is also recalculated according to the current A-axis and C-axis swing angles, and the XYZ coordinates of the subsequent tool path are corrected to avoid overcutting or undercutting of the blade profile.

[0056] In a specific implementation of this invention, before starting machining on a five-axis machining center, a force sensor is installed on the spindle bearing housing, and an acceleration sensor and an acoustic emission sensor are installed at the spindle end. A current sensor is connected in series with the spindle drive circuit. During machining, the data acquisition module synchronously collects cutting force, vibration, current, and acoustic emission status data in real time and transmits them to the wear monitoring module. The wear monitoring module filters and denoises the status data, extracts time-frequency domain features, and calculates the tool wear amount through a wear identification model. The compensation calculation module calculates the tool radius, length compensation correction value, and five-axis trajectory correction amount based on the wear amount. The execution compensation module writes the compensation value into the CNC system tool compensation register via Ethernet or fieldbus. The CNC system automatically executes the compensation in subsequent interpolation cycles, realizing online monitoring and closed-loop compensation of tool wear.

[0057] The contents not described in detail in this specification are existing technologies known to those skilled in the art.

[0058] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0059] The present invention and its embodiments have been described above. This description is not restrictive, and the accompanying drawings are only one embodiment of the present invention; the actual structure is not limited thereto. In conclusion, if those skilled in the art are inspired by this description and design similar structures and embodiments without departing from the spirit of the invention, such designs should fall within the protection scope of the present invention.

Claims

1. A five-axis machining center tool wear online monitoring and compensation system, comprising a five-axis machining center body, the five-axis machining center body including three linear axes (X-axis, Y-axis, and Z-axis) and two rotary axes (A-axis and C-axis), and a spindle clamped on the rotary axes, wherein a tool is clamped on the spindle, characterized in that: It also includes a data acquisition module, a wear monitoring module, a compensation calculation module, and a compensation execution module; The data acquisition module is set up corresponding to the spindle or tool to collect status data during the tool machining process; The wear monitoring module is connected to the data acquisition module, which extracts features from the status data, obtains tool wear feature parameters, and calculates the tool wear amount based on the tool wear feature parameters. The compensation calculation module is connected to the wear monitoring module and calculates the tool compensation value based on the tool wear. The execution compensation module is connected to the compensation calculation module and the CNC system of the five-axis machining center body, and inputs the tool compensation value into the CNC system to perform online compensation for the tool trajectory and tool offset.

2. The online monitoring and compensation system for tool wear in a five-axis machining center according to claim 1, characterized in that: The status data includes at least one of cutting force signal, vibration signal, spindle current signal, and acoustic emission signal.

3. The online monitoring and compensation system for tool wear in a five-axis machining center according to claim 1, characterized in that: The data acquisition module includes at least one of a force sensor, an acceleration sensor, a current sensor, and an acoustic emission sensor; The force sensor is located on the spindle bearing housing, the acceleration sensor is located on the spindle, the current sensor is connected in series with the spindle drive circuit, and the acoustic emission sensor is located on the spindle.

4. The online monitoring and compensation system for tool wear in a five-axis machining center according to claim 1, characterized in that: The wear monitoring module includes a signal preprocessing unit and a wear identification unit; The signal preprocessing unit performs filtering and noise reduction on the state data and extracts time-frequency domain features to obtain tool wear feature parameters. The wear identification unit calculates the tool wear amount based on the tool wear characteristic parameters.

5. The online monitoring and compensation system for tool wear in a five-axis machining center according to claim 1, characterized in that: The compensation calculation module includes a tool geometry compensation unit and a trajectory compensation unit; The tool geometry compensation unit corrects the tool radius compensation value and the tool length compensation value according to the tool wear amount; The trajectory compensation unit corrects the five-axis linkage machining trajectory based on the tool wear.

6. The online monitoring and compensation system for tool wear in a five-axis machining center according to claim 1, characterized in that: The execution compensation module includes a communication interface unit, which communicates with the CNC system via either Ethernet or fieldbus to write the tool compensation value into the tool compensation register of the CNC system.

7. A method for online monitoring and compensation of tool wear in a five-axis machining center, using the system as described in any one of claims 1-6, characterized in that: Includes the following steps: S1: Collect status data during the tool machining process through the data acquisition module; S2: The wear monitoring module extracts features from the status data, obtains tool wear feature parameters, and calculates the tool wear amount based on the tool wear feature parameters; S3: The compensation calculation module calculates the tool compensation value based on the tool wear amount; S4: The execution compensation module inputs the tool compensation value into the CNC system to perform online compensation for the tool path and tool offset.

8. The method for online monitoring and compensation of tool wear in a five-axis machining center according to claim 7, characterized in that: S2 includes filtering and denoising the state data and extracting time-frequency domain features to obtain tool wear feature parameters.

9. The method for online monitoring and compensation of tool wear in a five-axis machining center according to claim 7, characterized in that: S3 includes correcting the tool radius compensation value and tool length compensation value according to the tool wear amount, and correcting the five-axis linkage machining trajectory according to the tool wear amount.

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