A thermal error compensation system for an optical element processing CNC lathe

Abstract

The utility model relates to numerical control lathe technical field, concretely relates to a kind of thermal error compensation system for optical element processing numerical control lathe, comprising: multiple point temperature detection module, including multiple temperature sensors;Temperature acquisition and processing module, and multiple point temperature detection module are electrically connected by cable;Thermal error compensation module, integrated in temperature acquisition and processing module, for calculating the thermal displacement compensation amount according to the temperature signal after processing;Compensation output interface, it is set on temperature acquisition and processing module, for the thermal displacement compensation amount is output to numerical control system or servo driver;Servo driver is provided with independent compensation signal input port, the compensation signal input port is electrically connected with the compensation output interface, for receiving the thermal displacement compensation amount and the position instruction of motor is corrected in real time;Effective offset thermal deformation causes processing error, under the premise that machine tool mechanical structure is not greatly changed, significantly improve processing precision.

Description

Technical Field

[0001] This utility model relates to the field of CNC lathe technology, and specifically to a thermal error compensation system for a CNC lathe used in optical component processing. Background Technology

[0002] In the ultra-precision turning of optical components (such as laser crystals, infrared lenses, and freeform surfaces), the machining accuracy of CNC lathes directly affects the surface accuracy and quality of these components. During machine tool operation, the spindle motor, feed servo motor, ball screw assembly, and power devices all generate heat, leading to uneven thermal deformation of key mechanical structures such as the bed, spindle box, and guideways. This "thermal drift" error caused by thermal deformation, typically at the micrometer or even sub-micrometer level, has become a key factor restricting further improvements in the machining accuracy of optical components.

[0003] Currently, conventional CNC lathes mostly employ mechanical structure optimization (such as symmetrical design and selection of materials with low thermal expansion coefficients) or additional cooling systems (such as forced air cooling and liquid cooling) to suppress temperature rise and thermal deformation. However, these methods have limitations: mechanical structure optimization is costly and has limited effectiveness; cooling systems often only control the overall temperature, making it difficult to eliminate uneven deformation caused by local thermal gradients, and they cannot actively compensate for thermal deformation that has already occurred. More importantly, most existing economical CNC systems lack the function of electronic-level, real-time monitoring and compensation for thermally induced errors, or only rely on simple compensation based on a single temperature sensor, resulting in insufficient accuracy and reliability.

[0004] Therefore, there is an urgent need for a cost-effective, easy-to-implement solution that can effectively compensate for thermal errors in order to improve the long-term stability and machining accuracy of CNC lathes used for optical component processing. Utility Model Content

[0005] The purpose of this invention is to provide a thermal error compensation system for CNC lathes used in optical component processing. This system monitors the temperature field changes of key parts of the machine tool in real time through electrification and actively compensates for servo drive commands, thereby effectively offsetting the processing errors caused by thermal deformation and significantly improving processing accuracy without drastically altering the mechanical structure of the machine tool.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: A thermal error compensation system for a CNC lathe used in optical component processing includes: a multi-point temperature detection module comprising multiple temperature sensors arranged on the bed guide rails, spindle box, and lead screw seat; a temperature acquisition and processing module electrically connected to the multi-point temperature detection module via cables, used to acquire and process the temperature detection signals output by each temperature sensor; a thermal error compensation module integrated into the temperature acquisition and processing module, used to calculate the thermally induced displacement compensation amount based on the processed temperature signals; and a compensation output interface disposed on the temperature acquisition and processing module, used to output the thermally induced displacement compensation amount to the CNC system or servo driver; wherein the servo driver is provided with an independent compensation signal input port, which is electrically connected to the compensation output interface, used to receive the thermally induced displacement compensation amount and correct the motor position command in real time.

[0007] A further technical solution is that the bed guide rail, spindle box and lead screw seat are pre-set with multiple mounting holes or fixing slots for fixing the temperature sensor, and the temperature sensor is pressed against the metal surface of the corresponding installation position by a metal pressure plate or elastic element; the temperature sensor is a digital temperature sensor or a platinum resistance thermometer, and multiple temperature sensors are connected to the temperature acquisition and processing module by RS485 or I²C bus.

[0008] A further technical solution is that the temperature acquisition and processing module includes a microcontroller, a digital-to-analog converter circuit, and a front-end signal conditioning circuit adapted to the resistance temperature detector (RTD); the microcontroller is used to perform thermal error calculation, the RTD circuit is used to convert the digital compensation quantity into an analog voltage signal; and the compensation output interface is an analog voltage output interface.

[0009] A further technical solution is that the compensation output interface is an industrial fieldbus interface, which communicates with the CNC system via CAN, EtherCAT or Modbus protocols.

[0010] A further technical solution is that the temperature acquisition and processing module is equipped with a non-volatile memory for storing temperature compensation parameters, which can be updated through an external debugging interface.

[0011] A further technical solution is that the temperature acquisition and processing module is an independent PCB board, which is installed in the low-voltage module area of ​​the CNC lathe electrical cabinet. It is fixed in the electrical cabinet of the CNC lathe by guide rail clips or screws, and the PCB board has reserved multiple terminal interfaces for connecting the cables of the multi-point temperature sensors.

[0012] Compared with the prior art, the beneficial effects of this utility model are: This invention utilizes a distributed, multi-point temperature sensing network to accurately capture the thermal field distribution and trends of key machine tool components. Combined with a thermal error model, it provides real-time, forward-looking compensation, effectively suppressing the impact of thermal drift on machining accuracy. It is particularly suitable for the long-duration, high-load precision machining of optical components. This invention eliminates the need for expensive modifications or replacements of large mechanical structures such as the machine tool bed and guideways. The compensation function is primarily achieved through an additional electrical module, resulting in a simple structure, low implementation cost, and ease of upgrading existing machine tools. The temperature acquisition and processing module uses an independent PCB board, resulting in a compact structure that is easy to install in an electrical cabinet. The system compensation parameters are adjustable and can be adapted to different machine tools or machining conditions by updating the parameters in the memory or the compensation model, demonstrating strong versatility. The use of a bus-based sensor network and shielded cables reduces wiring complexity and signal interference. The modular design also facilitates system maintenance and replacement. Attached Figure Description

[0013] Figure 1 A schematic diagram showing the structure of the thermal error compensation system provided by this utility model and its connection with the control system of a CNC lathe used for optical element processing. Figure 2 This is a structural block diagram of the temperature acquisition and processing module in this utility model.

[0014] Icons: Multi-point temperature detection module 1, Temperature acquisition and processing module 2, Microcontroller 21, Digital-to-analog conversion circuit 22, Front-end signal conditioning circuit 23, Non-volatile memory 24, Thermal error compensation module 3, Compensation output interface 4. Detailed Implementation

[0015] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present utility model and are not intended to limit the present utility model.

[0016] Example 1 This utility model provides a thermal error compensation system for CNC lathes used in optical component processing, such as... Figure 1As shown, the control system of the CNC lathe for optical component processing includes a CNC system layer, a servo drive layer, and a mechanical execution layer. The CNC system layer contains the CNC system. The servo drive layer includes a servo driver and a compensation signal input terminal, so that the CNC system can send position commands to the servo driver of the servo drive layer. The mechanical execution layer includes a feed motor. The servo driver sends drive current to the feed motor so that the feed motor can drive the mechanical structure to operate. During operation, thermal deformation error will be generated, which will affect the accuracy of the mechanical structure. At this time, the thermal error compensation system obtains the thermal displacement compensation amount through the internal multi-point temperature detection module 1, temperature acquisition and processing module 2, and thermal error compensation algorithm, and outputs the thermal displacement compensation amount to the compensation signal input terminal of the servo drive layer through the compensation output interface 4. This utility model's thermal error compensation system adopts a modular, layered design. The system includes a multi-point temperature detection module 1, a temperature acquisition and processing module 2, a thermal error compensation module 3, and a compensation output interface 4. It forms a closed-loop compensation link with the servo drive of the CNC lathe. Specifically, the multi-point temperature detection module 1 consists of multiple temperature sensors. The sensor type is selected according to requirements: a digital temperature sensor (such as DS18B20, 1-Wire / I²C interface) or a platinum resistance thermometer (such as PT100 / PT1000). Multiple temperature sensors can be arranged on the bed guide rails, spindle box, and lead screw seat. Specifically, on the CNC lathe's bed guide rails (1-2 locations on each side for monitoring overall bed thermal expansion), the spindle box (2-3 locations near the spindle bearings for monitoring spindle frictional heat), and the lead screw seat (X-axis / Each of the Z-axis has one sensor mounting hole or fixing slot for monitoring the heat generation of the feed system. The temperature sensor is pressed against the metal surface of the mounting position by a metal pressure plate or elastic element to ensure temperature conduction efficiency and avoid detection delay caused by air gaps. Multiple temperature sensors are connected by RS485 or I²C bus, sharing two signal lines, which are led to the temperature acquisition and processing module 2 through shielded cables. The shielding layer is centrally grounded in the electrical cabinet to resist electromagnetic interference from the servo system.

[0017] Furthermore, such as Figure 2As shown, the temperature acquisition and processing module 2 is electrically connected to the multi-point temperature detection module 1 via a cable. It is used to acquire and process the temperature detection signals output by each temperature sensor. The temperature acquisition and processing module 2 includes a microcontroller 21, a digital-to-analog converter circuit 22, and a front-end signal conditioning circuit 23 adapted to the resistance temperature detector (RTD). The microcontroller 21 is used to perform thermal error calculation, and the RTD 22 is used to convert the digital compensation quantity into an analog voltage signal. The temperature acquisition and processing module 2 can be a separate PCB board (size can be selected as 150mm×100mm or 200mm×120mm, adaptable to mainstream electrical cabinet installation space). The internal components of this PCB board include: a microcontroller 21 (MCU, such as STM32F407, ARM Cortex-M4 core, 168MHz, used to perform temperature data processing and thermal error calculation), and a digital-to-analog converter circuit 22 (DAC, such as AD5624, 12-bit precision, 4...). The system includes: channel output (converting digital compensation values ​​into analog voltage signals), front-end signal conditioning circuit 23 (only required when using platinum resistance thermometers, containing a constant current source, operational amplifier, and low-pass filter circuit to eliminate lead wire errors and environmental noise from the platinum resistance thermometer), low-noise power supply circuit (LDO chip TPS7A4700, outputting a stable 3.3V / 5V voltage to power the sensor and internal chip), non-volatile memory 24 (EEPROM, such as AT24C64, 64Kbit capacity, used to store temperature compensation parameters, such as reference temperature, coefficient of thermal expansion, and compensation curve coefficient, which can be updated via an external debugging interface), and external debugging interface (USB or RS232 interface, used to update the compensation parameters in the EEPROM without disassembling the module). The installation method involves placing the temperature acquisition and processing module 2 in the low-voltage module area of ​​the CNC lathe electrical cabinet (away from servo drives, contactors, and other high-voltage components to reduce electromagnetic interference), secured by guide rail clips or M3 screws, and reserving multiple terminal interfaces on the PCB board for connecting shielded cables of multi-point temperature sensors.

[0018] Furthermore, the thermal error compensation module 3 is integrated into the temperature acquisition and processing module 2, and is used to calculate the thermally induced displacement compensation amount based on the processed temperature signal. Specifically, this module is not integrated as a separate hardware entity, but rather as a software program within the MCU of the temperature acquisition and processing module 2. The MCU periodically reads the detection signals from multiple temperature sensors, combines them with the compensation parameters stored in the EEPROM, and calculates the thermally induced displacement compensation amount (e.g., X-axis compensation ΔX = a1(T1-T0) + a2(T2-T0)) using a "linear / polynomial model". Where T0 is the reference temperature, T1 is the bed guide rail temperature, and T2 is the X-axis temperature. (The temperature of the lead screw seat, a1 / a2 are the calibrated coefficients of thermal expansion); the compensation output interface 4 is located on the temperature acquisition and processing module 2 and is used to output the thermally induced displacement compensation amount to the CNC system or servo drive. The servo drive is equipped with an independent compensation signal input port, which is electrically connected to the compensation output interface 4 to receive the thermally induced displacement compensation amount and correct the motor position command in real time. Specifically, the compensation output interface 4 is adapted to the servo drive, and according to the communication requirements between the CNC system and the servo drive, the compensation output interface 4 is divided into two types: ① Analog voltage output interface: from the DAC of the temperature acquisition and processing module 2. The circuit configuration outputs 0-5V analog voltage; ② Industrial fieldbus interface: supports CAN, EtherCAT or Modbus protocols, and transmits digital compensation quantities directly to the CNC system via the bus; The servo driver is equipped with an independent compensation signal input port (in the form of a plug or terminal), which is electrically connected to the compensation output interface 4 via a shielded cable: If it is an analog voltage interface, the driver directly receives the voltage signal and superimposes the compensation quantity before the position loop control; if it is a bus interface, the driver indirectly obtains the compensation quantity through the CNC system to realize real-time correction of the motor position command.

[0019] Working Principle: Taking the temperature acquisition and processing module as an example (using a PCB board), during operation, the MCU reads the temperature signal from a digital temperature sensor or platinum resistance thermometer. After filtering and amplification by the front-end signal conditioning circuit, the signal is sampled by the MCU's built-in ADC. The MCU calculates the Z-axis thermal displacement compensation amount based on the difference between the real-time temperature and the reference temperature, using the compensation formula. The compensation output interface outputs two signals simultaneously: the DAC converts the "Z-axis thermal displacement compensation amount" into a corresponding analog voltage and transmits it to the servo driver; the EtherCAT bus transmits the digital signal of the "Z-axis thermal displacement compensation amount" to the CNC system. The servo driver prioritizes receiving the analog voltage signal and superimposes the "Z-axis thermal displacement compensation amount" before executing the position command from the CNC system, driving the Z-axis motor to make slight adjustments to compensate for the position shift caused by thermal expansion.

[0020] The thermal error compensation system for CNC lathes used in optical component processing, provided by this utility model embodiment, offers the following advantages: Through a distributed multi-point temperature sensing network, it can accurately capture the thermal field distribution and changing trends of key machine tool components. Combined with a thermal error model, it provides real-time and forward-looking compensation, effectively suppressing the impact of thermal drift on machining accuracy. This system is particularly suitable for long-duration, high-load precision machining of optical components. This utility model eliminates the need for expensive modifications or replacements to large mechanical structures such as the machine tool bed and guideways. The compensation function is primarily achieved through additional electrical modules, resulting in a simple structure, low implementation cost, and ease of upgrading existing machine tools. The temperature acquisition and processing module uses an independent PCB board, which is compact and easy to install in an electrical cabinet. The system compensation parameters are adjustable and can be adapted to different machine tools or different processing conditions by updating the parameters in the memory or the compensation model, demonstrating strong versatility. The use of a bus-based sensor network and shielded cables reduces wiring complexity and signal interference. The modular design also facilitates system maintenance and replacement.

[0021] Although the present invention has been described herein with reference to several illustrative embodiments, it should be understood that many other modifications and implementations can be devised by those skilled in the art, which will fall within the scope and spirit of the principles disclosed herein. More specifically, various variations and modifications can be made to the components and / or layout of the subject matter combination within the scope of the drawings and claims disclosed herein. Besides variations and modifications to the components and / or layout, other uses will be apparent to those skilled in the art.

Claims

1. A thermal error compensation system for an optical element processing CNC lathe, characterized by, include: The multi-point temperature detection module includes multiple temperature sensors arranged on the bed guide rails, spindle box and lead screw seat; The temperature acquisition and processing module is electrically connected to the multi-point temperature detection module via a cable, and is used to acquire and process the temperature detection signals output by each temperature sensor; The thermal error compensation module, integrated into the temperature acquisition and processing module, is used to calculate the thermal displacement compensation amount based on the processed temperature signal. A compensation output interface is provided on the temperature acquisition and processing module to output the thermal displacement compensation amount to the CNC system or servo driver. The servo driver is equipped with an independent compensation signal input port, which is electrically connected to the compensation output interface. This port is used to receive the thermal displacement compensation amount and correct the motor position command in real time.

2. The thermal error compensation system for optical element machining CNC lathe according to claim 1, wherein, The bed guide rail, spindle box and lead screw seat are provided with multiple mounting holes or fixing slots for fixing the temperature sensor, and the temperature sensor is pressed against the metal surface of the corresponding installation position by metal pressure plate or elastic element. The temperature sensor is a digital temperature sensor or a platinum resistance thermometer, and multiple temperature sensors are connected to the temperature acquisition and processing module via RS485 or I²C bus.

3. The thermal error compensation system for optical element machining CNC lathe according to claim 1, wherein, The temperature acquisition and processing module includes a microcontroller, a digital-to-analog converter circuit, and a front-end signal conditioning circuit adapted to the resistance temperature detector (RTD). The microcontroller is used to perform thermal error calculation, and the digital-to-analog converter is used to convert the digital compensation amount into an analog voltage signal. The compensation output interface is an analog voltage output interface.

4. The thermal error compensation system for optical element machining CNC lathe according to claim 3, characterized in that, The compensation output interface is an industrial fieldbus interface, which communicates with the CNC system via CAN, EtherCAT or Modbus protocols.

5. The thermal error compensation system for optical element machining CNC lathe as claimed in claim 1 wherein, The temperature acquisition and processing module is equipped with a non-volatile memory for storing temperature compensation parameters, which can be updated through an external debugging interface.

6. The thermal error compensation system for optical element machining CNC lathe according to claim 1, wherein, The temperature acquisition and processing module is an independent PCB board. The temperature acquisition and processing module is installed in the low-voltage module area inside the electrical cabinet of the CNC lathe. It is fixed in the electrical cabinet of the CNC lathe by guide rail clips or screws. The PCB board has multiple terminal interfaces for connecting cables of multiple temperature sensors.

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