Cooling liquid temperature control system based on heat balance of machine tool

Abstract

The invention relates to the technical field of machine tool precision machining, in particular to a cooling liquid temperature control system based on machine tool heat balance, which is characterized in that a multi-dimensional temperature sensing module is used for synchronously collecting the temperatures of a plurality of characteristic positions of a machine tool body, the workshop environment temperature and the liquid inlet temperature, the liquid return temperature and the cutting area temperature in a cooling liquid circulation loop; the machining working condition and load sensing module communicates with a machine tool numerical control system and is used for obtaining motion instruction parameters and spindle real-time load signals in a machining program, and the multi-stage collaborative heat exchange module comprises a main heat exchange loop, an auxiliary heat exchange loop and a heat buffering unit. The heat balance cooperative control module is electrically connected with the multi-dimensional temperature sensing module, the machining working condition and load sensing module and the multi-stage cooperative heat exchange module. The balance cooperative control module is combined with main shaft load signals and working condition sudden change characteristics, working condition sudden change advanced early warning is achieved through the machining working condition and the load sensing module, and cutting heat sudden change is rapidly compensated in cooperation with the main multi-stage cooperative heat exchange design.

Description

Technical Field

[0001] This invention relates to the technical field of precision machining of machine tools, and specifically to a coolant temperature control system based on the thermal balance of machine tools. Background Technology

[0002] In the field of precision machining, the heat generated by machine tools during processing causes thermal expansion and deformation of the bed, spindle, and feed system. Coolant, as a key medium in the machine tool's thermal management system, directly affects the overall thermal balance of the machine tool and the dimensional accuracy of the workpiece. Especially in ultra-precision machining and high-consistency batch processing scenarios, the rationality of coolant temperature control strategies has become a crucial factor restricting further improvements in machining accuracy.

[0003] Most existing machine tool coolant constant temperature control systems adopt a technical approach that combines fixed temperature setting with fixed-frequency compressor start-stop control. This involves maintaining the coolant temperature at a preset value (e.g., 20°C) for an extended period, and using temperature sensors to detect changes in the coolant tank temperature to control the start and stop of the refrigeration unit to achieve constant temperature. For example, the machine tool cutting fluid constant temperature tank disclosed in CN217453198U and the CNC machine tool constant temperature cooling device disclosed in CN222002812U primarily rely on the tank structure, circulating pump, and refrigeration components to maintain a stable coolant temperature.

[0004] However, the above-mentioned technical approach has gradually revealed the following interrelated technical defects in practical applications:

[0005] Traditional systems typically set the coolant temperature to a fixed value without fully considering the dynamic changes in ambient temperature and machine tool bed reference temperature. When the ambient temperature is significantly higher than the coolant set value, for example, when the ambient temperature is 28°C but the coolant temperature is forcibly controlled at 20°C, the machine tool bed casting is prone to uneven temperature gradients during continuous heat exchange, leading to shrinkage or warping deformation in localized areas of the bed, with thermal deformation reaching approximately 0.02 mm / m or more.

[0006] This type of uneven thermal deformation will directly cause the relative positional shift between the tool and the workpiece, resulting in machining dimensional errors, and even amplifying the cumulative error in multi-axis linkage machining. At the same time, due to the temperature difference between the coolant temperature and the machine tool structure temperature, it will also exacerbate the imbalance of heat exchange inside the machine tool, making it difficult for the original constant temperature control strategy to maintain an overall thermally stable state.

[0007] Existing coolant temperature control systems mostly employ single-point temperature detection, with control logic primarily based on passive feedback, making it difficult to respond proactively to sudden changes in machining load. Although the high-precision machine tool cutting fluid and ambient temperature control system disclosed in announcement number CN116372653A achieves temperature regulation through dual pumps and a control unit, its control is still mainly based on the coolant temperature itself.

[0008] In actual machining processes, machine tool conditions often exhibit significant dynamic changes: when switching from finishing to roughing, the spindle load rate jumps rapidly, and the rate of heat generation increases accordingly. Because traditional systems lack coordinated utilization of heat source changes such as spindle load and machining cycle time, the cooling system typically takes 30 to 60 seconds to respond. During this period, the coolant temperature is prone to overshoot fluctuations of 2 to 3°C, leading to a significant increase in workpiece thermal expansion and contraction errors and a higher dimensional tolerance rate.

[0009] To achieve liquid temperature stability at the ±0.1°C level, existing systems often require frequent start-stop of the compressor or maintaining the refrigeration unit in a high-frequency operating state, resulting in high energy consumption and equipment wear. On the other hand, the intermittent refrigeration method adopted to reduce energy consumption is prone to introducing obvious temperature sawtooth fluctuations, making it difficult to balance energy efficiency and processing accuracy requirements.

[0010] Existing machine tool coolant constant temperature control technologies generally focus on the static control of coolant temperature, failing to consider the thermal balance of the machine tool structure and the dynamic changes in machining load to build a coordinated regulation mechanism between coolant temperature, ambient temperature, and machine tool thermal state. This makes it difficult to meet the higher requirements of high-precision and high-stability machining for thermal management systems. Summary of the Invention

[0011] Therefore, the purpose of this invention is to provide a coolant temperature control system based on machine tool thermal balance, which relies on machining condition and load sensing modules to realize early warning of sudden changes in working conditions, and cooperates with a multi-stage collaborative heat exchange design to quickly compensate for sudden changes in cutting heat.

[0012] To achieve the above objectives, the present invention provides the following technical solution:

[0013] A coolant temperature control system based on machine tool thermal balance includes:

[0014] The multi-dimensional temperature sensing module is used to simultaneously collect the temperature of multiple characteristic locations on the machine tool bed, the ambient temperature of the workshop, and the inlet temperature, return temperature, and cutting zone temperature in the coolant circulation loop.

[0015] The machining condition and load sensing module communicates with the machine tool CNC system to obtain motion command parameters and real-time spindle load signals in the machining program, and identifies sudden changes in working conditions such as the switching between roughing and finishing based on changes in machining parameters and spindle load.

[0016] The multi-stage collaborative heat exchange module includes a main heat exchange loop with thermal inertia, a secondary heat exchange loop with high response characteristics, and a thermal buffer unit to reduce the conduction of temperature fluctuations.

[0017] The thermal balance collaborative control module is electrically connected to the multi-dimensional temperature sensing module, the processing condition and load sensing module, and the multi-level collaborative heat exchange module, respectively.

[0018] The thermal balance collaborative control module constructs a thermal balance reference temperature that reflects the overall thermal state of the machine tool based on the weighted fusion result of the temperature at multiple characteristic locations of the machine bed and combined with the trend of ambient temperature change. Based on the thermal balance reference temperature, it generates a dynamic target temperature of coolant that varies with the thermal state of the machine bed.

[0019] Meanwhile, the thermal balance collaborative control module combines the spindle load signal and the characteristics of sudden changes in working conditions to output control commands that combine feedforward and feedback, and coordinates the heat exchange intensity of the main heat exchange circuit, the working state of the secondary heat exchange circuit, and the heat exchange path of the thermal buffer unit, thereby achieving coordinated matching between the coolant temperature and the machine tool thermal state and ambient temperature under different processing conditions.

[0020] The present invention is further configured such that: the multi-dimensional temperature sensing module includes multiple bed temperature sensors arranged on the machine tool spindle box, worktable and bed force reference surface, and an ambient temperature sensor arranged in the non-heat source area of ​​the workshop;

[0021] The thermal balance collaborative control module performs weighted fusion processing on the temperature signals collected by each bed temperature sensor, and corrects the fusion result based on the changing trend of ambient temperature to obtain the thermal balance reference temperature.

[0022] The dynamic target temperature of the coolant is set based on the thermal balance reference temperature, and the temperature difference between the two is controlled within a preset allowable range.

[0023] The present invention is further configured such that: the thermal balance collaborative control module has a built-in segmented ambient temperature compensation logic, and sets an ambient temperature change rate threshold;

[0024] When the real-time ambient temperature change rate is less than or equal to the threshold, the thermal balance reference temperature is corrected using a first environmental compensation coefficient.

[0025] When the real-time ambient temperature change rate is greater than the threshold, the system switches to a second environmental compensation coefficient for correction. The second environmental compensation coefficient is greater than the first environmental compensation coefficient to adapt to the thermal balance adjustment requirements under different ambient temperature change rates.

[0026] The present invention is further configured such that: the processing condition and load sensing module includes a program parsing unit, a load monitoring unit, and a condition identification unit;

[0027] The program parsing unit is used to parse machining parameters such as cutting depth, feed rate and spindle speed in the machining program;

[0028] The load monitoring unit is used to collect real-time load signals of the spindle.

[0029] The working condition identification unit identifies working condition change characteristics such as the switching between roughing and finishing based on changes in machining parameters and sudden changes in spindle load, and outputs a working condition change warning signal within a preset time window before the working condition change occurs.

[0030] The present invention is further configured such that: the processing condition and load sensing module also includes a thermal load mapping unit.

[0031] The thermal load mapping unit generates a thermal load reference value that characterizes the trend of the rate of change of cutting heat generation based on the analytically obtained machining parameters, spindle load signal and pre-stored material-tool thermal load coefficient, and uses the thermal load reference value as the input parameter for the feedforward control of the thermal balance collaborative control module.

[0032] The present invention is further configured such that: in the multi-stage coordinated heat exchange module:

[0033] The main heat exchange circuit includes a main liquid tank, a variable frequency refrigeration unit, and a main heat exchanger.

[0034] The secondary heat exchange circuit includes a heat buffer tank and at least one high-frequency response heat exchange component. The high-frequency response heat exchange component has a faster response speed than the variable frequency refrigeration unit and is used to quickly compensate for the coolant temperature when the operating conditions change abruptly.

[0035] The thermal buffer unit includes a phase change energy storage material layer and a temperature adaptive flow guiding structure disposed in the coolant flow path, which is used to absorb or release transient heat caused by sudden changes in operating conditions, so as to weaken the thermal shock of transient adjustment of the secondary heat exchange circuit to the main heat exchange circuit.

[0036] The present invention is further configured such that: a spiral guide plate and a variable frequency stirring device are provided inside the large volume liquid tank;

[0037] The thermal balance collaborative control module dynamically adjusts the rotation speed of the variable frequency stirring device based on the difference between the inlet and outlet temperatures of the coolant, in order to reduce temperature stratification inside the tank.

[0038] The present invention is further configured such that: the thermal balance collaborative control module adopts a feedforward-feedback composite control method, wherein:

[0039] Feedforward control adjusts the cooling capacity of the main heat exchange circuit or starts the auxiliary heat exchange circuit for pre-compensation based on the early warning signal of sudden change in operating conditions and the heat load reference.

[0040] Feedback control corrects the operating parameters of the main heat exchange loop and the auxiliary heat exchange loop based on the deviation between the actual temperature of the coolant and the dynamic target temperature of the coolant.

[0041] During the stable operating phase, feedback control of the main heat exchange loop is the primary method; during the phase of sudden changes in operating conditions, the control mode switches to one dominated by feedforward control, with the main and auxiliary heat exchange loops working in coordination.

[0042] The present invention is further configured to include a multi-component thermal coordination module for the machine tool and a coolant status monitoring module;

[0043] The multi-component thermal coordination module of the machine tool is used to collect the temperature information of the independent cooling circuits corresponding to the machine tool spindle, lead screw and guide rail. When the deviation between the temperature of any independent cooling circuit and the thermal balance reference temperature exceeds the allowable range, the flow rate of the corresponding cooling circuit and the heat exchange parameters of the main heat exchange circuit are adjusted synchronously to avoid decoupling of the cooling state of each component from the overall thermal balance state of the machine tool and causing additional thermal deformation.

[0044] The coolant status monitoring module is used to monitor the flow rate and changes in thermophysical parameters of the coolant. When the detection results meet the preset maintenance conditions, it outputs a maintenance prompt signal.

[0045] Compared with the shortcomings of the prior art, the beneficial effects of the present invention are as follows:

[0046] By using multi-dimensional temperature sensing and segmented environmental compensation, a thermal balance reference temperature is constructed to dynamically adapt to the random bed thermal state and ambient temperature, so that the coolant temperature drifts synchronously with the machine tool thermal state, avoiding the thermal stress caused by traditional fixed constant temperature and reducing the amount of bed thermal deformation.

[0047] By relying on the processing condition and load sensing module, it realizes early warning of sudden changes in working conditions, and with the main multi-stage collaborative heat exchange design, it can quickly compensate for sudden changes in cutting heat.

[0048] By coordinating the thermal regulation of multiple machine tool components, the cooling status of core components such as the spindle, lead screw, and guide rails is ensured to match the overall thermal balance. Combined with coolant status monitoring, performance degradation is prevented from affecting heat exchange efficiency. Attached Figure Description

[0049] Fig. 1 This is a flowchart illustrating the system framework of the present invention.

[0050] Fig. 2 This is a framework diagram of the multi-stage collaborative heat exchange module of the present invention. Detailed Implementation

[0051] Reference Figs. 1-2 The embodiments of the present invention will be further described below.

[0052] This embodiment discloses a coolant temperature control system based on machine tool thermal balance. Its core includes a multi-dimensional temperature sensing module, a machining condition and load sensing module, a multi-level collaborative heat exchange module, a thermal balance collaborative control module, and extended multi-component thermal collaboration modules and coolant status monitoring modules. Each module interacts with the CAN bus via industrial Ethernet (Profinet protocol). The thermal balance collaborative control module, as the core control unit, coordinates signal processing and command output, forming a closed-loop control system of sensing-judgment-adjustment-monitoring. The specific implementation details of each module and the system's collaborative working logic are described in detail below.

[0053] Multi-dimensional temperature sensing module: Used to synchronously collect temperature signals from the machine tool, environment, and coolant across all dimensions, providing data support for the construction of thermal equilibrium reference temperature. Specific implementation details are as follows:

[0054] Four PT1000 high-precision platinum resistance sensors (measuring range -50℃ to 200℃, accuracy ±0.01℃, response time ≤50ms) are selected and fixed to four core locations on the machine tool via threaded mounting brackets: the mounting surface connecting the spindle box and the bed (close to the spindle bearing area, with the highest sensitivity to thermal deformation); the bottom of the T-slot in the center of the worktable (directly reflecting the thermal state of the workpiece bearing area); the bed force reference surface (close to the guide rail mounting surface, related to the thermal deformation of the feed system); and the end face of the leadscrew bearing seat (supplementing the thermal state data of the feed system). Thermal grease is applied between the sensor probe and the mounting surface to ensure efficient heat conduction. After installation, a waterproof sealing sleeve is used to encapsulate the sensor and prevent coolant corrosion.

[0055] A digital temperature sensor (measurement range -10℃~60℃, accuracy ±0.1℃) is selected and installed in a well-ventilated area away from the machine tool heat source in the workshop (≥5m away from the nearest machine tool). It is fixed on a metal bracket to avoid direct sunlight and airflow. The sampling frequency is set to 10Hz.

[0056] Two K-type thermocouple sensors (measuring range 0℃~100℃, accuracy ±0.05℃) are selected and installed in the inlet and return lines of the coolant circulation loop, respectively: the inlet sensor is installed at the connection between the main heat exchange loop outlet and the cutting zone pipeline, and the return sensor is installed at the connection between the cutting zone return pipeline and the main coolant tank; clamp-type installation is adopted, with the probe inserted into the pipeline to a depth of 1 / 3 of the pipe diameter and in direct contact with the coolant.

[0057] An infrared temperature sensor (measurement range -20℃~300℃, accuracy ±0.1℃, response time ≤10ms) is selected and fixed to the side of the machine tool spindle by a bracket. The temperature measuring lens is aimed at the contact area between the tool and the workpiece, and the lens is equipped with a dustproof and waterproof cover to avoid contamination by cutting chips and coolant.

[0058] Signal processing and thermal equilibrium reference temperature construction:

[0059] The thermal balance collaborative control module performs weighted fusion of signals collected by four bed temperature sensors. The weighting coefficients are determined experimentally based on the thermal deformation sensitivity of each installation position: 0.4 for the spindle box mounting surface, 0.3 for the worktable center, 0.2 for the bed force reference surface, and 0.1 for the lead screw bearing seat end face. The fusion formula is: T = 0.4 × T + 0.3 × T + 0.2 × T + 0.1 × T.

[0060] The built-in segmented compensation logic sets the threshold for the rate of change of ambient temperature to 0.5℃ / h. The temperature change rate is calculated every 10 seconds based on real-time data from the ambient temperature sensor. When the rate of change is ≤0.5℃ / h, the first environmental compensation coefficient K1=0.1 is used for correction. When the rate of change is >0.5℃ / h, the second environmental compensation coefficient K2=0.3 (K2=3×K1) is used. The correction formula is: T=T+K×(TT), where T is the ambient temperature reference value when the machine tool starts.

[0061] The dynamic target temperature of the coolant is set based on the thermal balance reference temperature, and the temperature difference between the two is preset to an allowable range of ±0.5℃, i.e., T∈[T-0.5℃,T+0.5℃], to ensure that the coolant temperature drifts synchronously with the thermal state of the machine tool.

[0062] Processing condition and load sensing module: Used to acquire processing condition and load information during the processing, identify sudden changes in processing conditions and generate thermal load reference values, providing input for feedforward control. Specific implementation is as follows:

[0063] The module uses a microcontroller as the core processing unit and establishes communication with the machine tool CNC system through an industrial Ethernet interface (RJ45). It uses the OPCUA protocol to read the machining program and spindle load data in real time. At the same time, it interacts with the thermal balance co-control module through the CAN bus, with the communication baud rate set to 500kbps.

[0064] Program parsing unit: The program parsing unit uses regular expression algorithms to parse the machining program (G code / M code) and extract core motion command parameters such as cutting depth ap (mm), feed rate f (mm / r), spindle speed n (r / min) and tool diameter D (mm). The parsing frequency is synchronized with the machining program execution frequency (parameters are extracted once every 10 segments of G code are parsed). The parsing results are stored in the module's built-in Flash memory (storage capacity ≥1MB).

[0065] Load monitoring unit: It acquires the real-time load signal (load rate, in %) of the spindle through the spindle load feedback interface of the CNC system, and the sampling frequency is set to 20Hz; at the same time, it acquires the spindle current signal to help verify the load status, and the current measurement accuracy is ±0.1A.

[0066] Working condition identification unit: The preset spindle load change threshold is 30% (load rate change ≥30% per unit time). Combined with the changes in machining parameters extracted by the program parsing unit (such as the cutting depth jumping from 0.5mm (finishing) to 3mm (roughing)), it identifies working condition change characteristics such as roughing and finishing switching. The warning time window is set to 500ms. When a working condition change characteristic is detected, a high-level effective (voltage 3.3V) working condition change warning signal is output to the thermal balance collaborative control module 500ms in advance.

[0067] The thermal load mapping unit pre-stores the matching thermal load coefficient K (unit: W / (mm³·min)) for 50 common machining materials (45# steel, 6061 aluminum alloy, TC4 titanium alloy, etc.) and 25 commonly used cutting tools (carbide end mills, diamond grinding wheels, etc.), forming a thermal load coefficient database. Based on the analytical machining parameters and spindle load signal, the cutting heat generation rate is calculated through the thermal load model: Q=K×ap×f×n×π×D / 1000. The calculation result is output as a thermal load reference quantity to the thermal balance collaborative control module as a feedforward control input. Example: When roughing TC4 titanium alloy with a φ10mm carbide end mill, K=1.2W / (mm³·min), ap=3mm, f=100mm / r, n=6000r / min, and the calculated Q=7.065kW.

[0068] The multi-stage collaborative heat exchange module includes:

[0069] Main heat exchange circuit 101 includes a large-capacity main liquid tank 1, a variable frequency refrigeration unit 2, a main heat exchanger 3, and a circulating pump 4. The large-capacity liquid tank has a volume of 100L. The variable frequency refrigeration unit uses a scroll-type variable frequency compressor with a cooling capacity adjustment range of 5~15kW, a frequency conversion range of 30~60Hz, and a COP ≥ 3.8. The main heat exchanger is a plate heat exchanger with a heat exchange area of ​​2m². The circulating pump is a centrifugal pump with a flow rate adjustment range of 10~20L / min, a head ≥ 15m, and variable frequency speed control function.

[0070] The main liquid tank is equipped with a variable frequency stirring device (power 500W, speed adjustment range 50~300r / min).

[0071] The thermal balance control module dynamically adjusts the stirring speed based on the difference between the inlet and outlet temperatures of the coolant: when the temperature difference is >0.2℃, it runs at a high speed of 200~300r / min; when the temperature difference is ≤0.1℃, it runs at a low speed of 50~100r / min to reduce temperature stratification inside the tank.

[0072] The secondary heat exchange circuit 102 includes a small-volume heat buffer tank 5, a high-frequency response heat exchange assembly 6, and an electric three-way valve 7. The small-volume heat buffer tank has a volume of 8L and a built-in level sensor to ensure the liquid level is maintained at 1 / 2 to 3 / 4 of the height. The high-frequency response heat exchange assembly uses a combination of a semiconductor refrigeration component and an electric heating component. The semiconductor refrigeration component has a cooling power adjustment range of 1~3kW and a response time of ≤20ms. The electric heating component has a heating power of 1~2kW (PTC heating element, with good constant temperature characteristics). The electric three-way valve is electromagnetic, with a response time of ≤100ms, a nominal diameter of DN25, and a pressure resistance of ≥1.6MPa, enabling selective connection between the main and secondary circuits.

[0073] Connection and control logic: The secondary loop 102 is connected in parallel with the main loop 101. The common terminal of the electric three-way valve 7 is connected to the outlet of the main liquid tank 1, and its two working terminals are connected to the inlet of the main heat exchanger 3 and the inlet of the secondary loop heat buffer tank 3, respectively. The outlet terminals converge to the main coolant circulation pipeline 100. When the operating conditions are stable, the three-way valve opens the main loop and closes the secondary loop. When a sudden change in operating conditions is detected or a liquid temperature change rate ≥0.1℃ / ms is detected, the system switches to the secondary loop or the main and secondary loops work together to quickly compensate for temperature fluctuations through the high-frequency response heat exchange components.

[0074] Thermal buffer unit 8: Installed at the connection between the secondary circuit outlet and the main circuit consolidation pipeline, it adopts a cylindrical cavity structure with a phase change energy storage material layer attached to the inner wall of the cavity. When the operating conditions change abruptly, the transient temperature fluctuations output by the secondary circuit first pass through the thermal buffer unit, and the phase change energy storage material absorbs / releases instantaneous heat to ensure a smooth transition of the coolant temperature after consolidation.

[0075] Thermal balance coordinated control module: A feedforward-feedback composite control method is used to achieve coordinated scheduling of various modules, and the specific implementation is as follows:

[0076] It uses a microcontroller as the core processing chip to process analog signals from various sensors; it is equipped with multiple UART, SPI, and CAN interfaces to enable communication with other modules; the power supply module adopts a wide voltage input and has overvoltage, overcurrent, and reverse connection protection functions.

[0077] Feedforward control strategy: Based on the early warning signal of sudden changes in operating conditions and the reference value of heat load output by the processing condition and load sensing module, the working status of the multi-stage collaborative heat exchange module is adjusted in advance. Example: When a roughing and finishing switching warning is received, the frequency of the main circuit variable frequency chiller unit is increased from 40Hz to 50Hz 500ms in advance, and the secondary circuit semiconductor cooling component is started up to 70% power to achieve feedforward compensation of "temperature control before heat is generated".

[0078] Feedback control strategy: Based on the deviation between the actual coolant temperature and the dynamic target temperature collected by the multi-dimensional temperature sensing module, the operating parameters of the main and auxiliary heat exchange loops are corrected. PID deviation adjustment logic is adopted: when the deviation is >0.3℃, the cooling power of the main loop or the compensation power of the auxiliary loop is increased; when the deviation is ≤0.1℃, the current parameters are kept stable to ensure that the liquid temperature control accuracy is ≤±0.08℃.

[0079] Control mode switching: During the stable operating phase (spindle load rate fluctuation ≤10%, no sudden changes in operating conditions), the main heat exchange loop feedback control is the primary mode, the secondary loop is on standby, and the thermal buffer unit works adaptively; During the sudden change in operating conditions (receiving a sudden change warning or load rate fluctuation >30%), the control mode switches to feedforward control as the primary mode and the main and secondary loops work together. The thermal buffer unit works hard to reduce fluctuations and ensures that the liquid temperature overshoot is ≤0.5℃.

[0080] Implementation of multi-component thermal coordination module and coolant condition monitoring module for machine tools:

[0081] PT100 sensors (accuracy ±0.05℃) are installed at the independent cooling circuit outlets of the machine tool spindle, lead screw, and X / Y / Z axis guideways to collect the temperature information of the cooling circuit of each component in real time, with a sampling frequency of 5Hz.

[0082] When the temperature of any component's cooling circuit deviates from the thermal balance reference temperature by ≥1℃, the thermal balance collaborative control module simultaneously performs two adjustments:

[0083] Adjust the electromagnetic flow valve of the corresponding component's cooling circuit (flow adjustment range 0.5~5L / min, accuracy ±0.1L / min) to increase or decrease the cooling flow rate;

[0084] Adjust the frequency of the main heat exchange circuit variable frequency refrigeration unit to ensure that the cooling status of each component matches the overall thermal balance of the machine tool. Example: When the spindle cooling circuit temperature is 1.2℃ higher than the thermal balance reference temperature, increase the spindle circuit flow rate from 2L / min to 3L / min, and simultaneously increase the main circuit cooling frequency by 5Hz.

[0085] Coolant status monitoring module: Monitoring parameters and sensors include coolant flow rate, impurity content, and thermophysical parameters. Flow rate monitoring uses an electromagnetic flow sensor (installed in the main circuit inlet pipe, measurement range 5~30L / min, accuracy ±0.1L / min); impurity content monitoring uses a laser particle counter (measurement range 1~100μm, accuracy ±1 particle / μL); thermophysical parameters are measured periodically using a portable thermal conductivity meter (measurement range 0.1~1.0W / (m·K)) and a specific heat capacity meter (measurement range 1.5~4.5kJ / (kg·℃)) (recommended every 8 hours).

[0086] Preset maintenance conditions: flow rate ≤ 8L / min; impurity content ≥ 10 particles / μL; thermal conductivity or specific heat capacity change rate relative to initial value ≥ 10%. When any of the test results meet the conditions, the thermal balance co-control module outputs a maintenance prompt signal (red LED indicator light stays on + buzzer alarm, and fault parameters are displayed in a pop-up window on the touch screen), reminding the operator to replace the coolant, filter, or clean the pipeline.

[0087] System collaborative workflow:

[0088] Step 1: System initialization and startup, each module completes self-test (sensor calibration, communication link detection, component status detection); the multi-dimensional temperature sensing module collects the initial ambient temperature T and the temperature of each characteristic position of the bed; the machining condition and load sensing module establishes communication with the machine tool CNC system and loads the thermal load coefficient database.

[0089] Step 2: The thermal balance collaborative control module weights and fuses the initial bed temperature signal, combines it with the initial ambient temperature to generate the initial thermal balance reference temperature, and sets the initial coolant dynamic target temperature (temperature difference ±0.5℃).

[0090] Step 3: The machine tool starts processing. The multi-dimensional temperature sensing module simultaneously collects the bed temperature, ambient temperature, coolant inlet and outlet temperatures, and cutting zone temperature and transmits them to the thermal balance collaborative control module. The processing condition and load sensing module simultaneously analyzes the processing program, collects the spindle load signal, and identifies the working condition status.

[0091] Step 4: The thermal balance collaborative control module dynamically updates the thermal balance reference temperature and the dynamic target temperature of the coolant based on the real-time bed temperature and the rate of change of ambient temperature; when the machining condition and load sensing module identifies the characteristics of sudden changes in the working condition, it outputs an early warning signal and thermal load reference value 500ms in advance.

[0092] Step 5: The thermal balance collaborative control module outputs feedforward-feedback composite control commands: when the operating conditions are stable, adjust the cooling power and stirring speed of the main heat exchange circuit; when the operating conditions change abruptly, start the high-frequency response heat exchange component of the secondary circuit to work in coordination with the main circuit, and the thermal buffer unit weakens temperature fluctuations.

[0093] Step 6: The multi-component thermal coordination module of the machine tool monitors the temperature of the spindle, lead screw, and guide rail cooling circuit in real time. When the deviation exceeds the limit, the flow rate and main circuit parameters are adjusted synchronously. The coolant status monitoring module continuously monitors the coolant status and outputs a prompt signal when the maintenance conditions are met.

[0094] Step 7: After processing is completed, the system enters a low-power standby mode to maintain the coolant temperature within ±1℃ of the thermal equilibrium reference temperature, so as to facilitate a quick transition to a stable state for the next processing.

[0095] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any ordinary changes and substitutions made by those skilled in the art within the scope of the technical solution of the present invention should be included within the protection scope of the present invention.

Claims

1. A coolant temperature control system based on machine tool thermal balance, characterized in that, include: The multi-dimensional temperature sensing module is used to simultaneously collect the temperature of multiple characteristic locations on the machine tool bed, the ambient temperature of the workshop, and the inlet temperature, return temperature, and cutting zone temperature in the coolant circulation loop. The machining condition and load sensing module communicates with the machine tool CNC system to obtain motion command parameters and real-time spindle load signals in the machining program, and identifies sudden changes in working conditions such as the switching between roughing and finishing based on changes in machining parameters and spindle load. The multi-stage coordinated heat exchange module includes a main heat exchange loop, a secondary heat exchange loop, and a thermal buffer unit; The thermal balance collaborative control module is electrically connected to the multi-dimensional temperature sensing module, the processing condition and load sensing module, and the multi-level collaborative heat exchange module, respectively. The thermal balance collaborative control module constructs a thermal balance reference temperature that reflects the overall thermal state of the machine tool based on the weighted fusion result of the temperature at multiple characteristic locations of the machine bed and combined with the trend of ambient temperature change. Based on the thermal balance reference temperature, it generates a dynamic target temperature of coolant that varies with the thermal state of the machine bed. Meanwhile, the thermal balance collaborative control module combines the spindle load signal and the characteristics of sudden changes in working conditions to output control commands that combine feedforward and feedback. It coordinates and adjusts the heat exchange intensity of the main heat exchange circuit, the working state of the secondary heat exchange circuit, and the heat exchange path of the thermal buffer unit, thereby achieving coordinated matching between the coolant temperature and the machine tool thermal state and ambient temperature under different processing conditions.

2. The coolant temperature control system based on machine tool thermal balance according to claim 1, characterized in that: The multi-dimensional temperature sensing module includes multiple bed temperature sensors arranged on the machine tool spindle box, worktable and bed force reference surface, as well as an ambient temperature sensor arranged in the non-heat source area of ​​the workshop. The thermal balance collaborative control module performs weighted fusion processing on the temperature signals collected by each bed temperature sensor, and corrects the fusion result based on the changing trend of ambient temperature to obtain the thermal balance reference temperature. The dynamic target temperature of the coolant is set based on the thermal balance reference temperature, and the temperature difference between the two is controlled within a preset allowable range.

3. The coolant temperature control system based on machine tool thermal balance according to claim 2, characterized in that: The thermal balance collaborative control module has a built-in segmented ambient temperature compensation logic and sets an ambient temperature change rate threshold. When the real-time ambient temperature change rate is less than or equal to the threshold, the thermal balance reference temperature is corrected using a first environmental compensation coefficient. When the real-time ambient temperature change rate is greater than the threshold, the system switches to a second environmental compensation coefficient for correction. The second environmental compensation coefficient is greater than the first environmental compensation coefficient to adapt to the thermal balance adjustment requirements under different ambient temperature change rates.

4. The coolant temperature control system based on machine tool thermal balance according to claim 1, characterized in that: The processing condition and load sensing module includes a program parsing unit, a load monitoring unit, and a condition identification unit. The program parsing unit is used to parse machining parameters such as cutting depth, feed rate and spindle speed in the machining program; The load monitoring unit is used to collect real-time load signals of the spindle. The working condition identification unit identifies working condition change characteristics such as the switching between roughing and finishing based on changes in machining parameters and sudden changes in spindle load, and outputs a working condition change warning signal within a preset time window before the working condition change occurs.

5. A coolant temperature control system based on machine tool thermal balance according to claim 4, characterized in that: The processing condition and load sensing module also includes a thermal load mapping unit. The thermal load mapping unit generates a thermal load reference value that characterizes the trend of the rate of change of cutting heat generation based on the analytically obtained machining parameters, spindle load signal and pre-stored material-tool thermal load coefficient, and uses the thermal load reference value as the input parameter for the feedforward control of the thermal balance collaborative control module.

6. A coolant temperature control system based on machine tool thermal balance according to claim 5, characterized in that: In the multi-stage collaborative heat exchange module: The main heat exchange circuit includes a main liquid tank, a variable frequency refrigeration unit, and a main heat exchanger. The secondary heat exchange circuit includes a heat buffer tank and at least one high-frequency response heat exchange component. The high-frequency response heat exchange component has a faster response speed than the variable frequency refrigeration unit and is used to quickly compensate for the coolant temperature when the operating conditions change abruptly. The thermal buffer unit includes a phase change energy storage material layer disposed in the coolant flow path to absorb or release transient heat caused by sudden changes in operating conditions, so as to weaken the thermal shock to the main heat exchange circuit caused by transient regulation of the secondary heat exchange circuit.

7. A coolant temperature control system based on machine tool thermal balance according to claim 6, characterized in that: The large-capacity liquid tank is equipped with a spiral guide plate and a variable frequency stirring device. The thermal balance collaborative control module dynamically adjusts the rotation speed of the variable frequency stirring device based on the difference between the inlet and outlet temperatures of the coolant, in order to reduce temperature stratification inside the tank.

8. A coolant temperature control system based on machine tool thermal balance according to claim 7, characterized in that: The thermal balance collaborative control module adopts a feedforward-feedback composite control method, wherein: Feedforward control adjusts the cooling capacity of the main heat exchange circuit or starts the auxiliary heat exchange circuit for pre-compensation based on the early warning signal of sudden change in operating conditions and the heat load reference. Feedback control corrects the operating parameters of the main heat exchange loop and the auxiliary heat exchange loop based on the deviation between the actual temperature of the coolant and the dynamic target temperature of the coolant. During the stable operating phase, feedback control of the main heat exchange loop is the primary method; during the phase of sudden changes in operating conditions, the control mode switches to one dominated by feedforward control, with the main and auxiliary heat exchange loops working in coordination.

9. A coolant temperature control system based on machine tool thermal balance according to any one of claims 1-8, characterized in that: It also includes a multi-component thermal coordination module for machine tools and a coolant status monitoring module; The multi-component thermal coordination module of the machine tool is used to collect the temperature information of the independent cooling circuits corresponding to the machine tool spindle, lead screw and guide rail. When the deviation between the temperature of any independent cooling circuit and the thermal balance reference temperature exceeds the allowable range, the flow rate of the corresponding cooling circuit and the heat exchange parameters of the main heat exchange circuit are adjusted synchronously to avoid decoupling of the cooling state of each component from the overall thermal balance state of the machine tool and causing additional thermal deformation. The coolant status monitoring module is used to monitor the flow rate and changes in thermophysical parameters of the coolant. When the detection results meet the preset maintenance conditions, it outputs a maintenance prompt signal.

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