Temperature control method of machine tool cooling system, machine tool cooling system and machine tool
Patent Information
- Application Number
- CN202610965705.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-06-30
- Publication Date
- 2026-09-25
Smart Images
Figure CN122807670A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of CNC machine tool technology, and more specifically, to a temperature control method for a machine tool cooling system, a machine tool cooling system, and a machine tool. Background Technology
[0002] Currently, with the rapid development of modern manufacturing towards high precision and high efficiency, high-end CNC machine tools such as double-gantry five-axis CNC machining centers are increasingly widely used in aerospace, precision mold making, and automotive parts manufacturing. These machine tools typically have complex machining processes and extremely high requirements for machining accuracy. Because machine tools generate a large amount of cutting heat and frictional heat during high-speed operation or high-power cutting, if the cooling system cannot remove this heat in a timely and stable manner, key machine tool components (such as spindles, lead screws, and beds) will undergo thermal deformation, directly leading to dimensional deviations and severely affecting the machining accuracy and surface quality of the workpiece. Therefore, the temperature control accuracy and stability of the machine tool cooling system have become one of the key factors determining the overall machining performance of the machine tool.
[0003] In existing technologies, machine tool coolers mainly employ a feedback-based temperature control strategy, which adjusts the cooling output solely by detecting the inlet and outlet temperatures of the cooling medium. Specifically, when the detected outlet temperature is higher than the set value, the cooler increases the compressor frequency to increase cooling capacity; when the detected outlet temperature is lower than the set value, it decreases the compressor frequency to reduce cooling capacity.
[0004] However, during machine tool operation, the heat load often changes drastically and suddenly. For example, when a machine tool suddenly switches from a low-load condition to a high-load condition, the heat generated inside the machine tool will surge instantly; conversely, when the load suddenly decreases, the heat generation will decrease instantly. Since the compressor needs a certain response time to adjust from the current frequency to the target frequency, during this "adjustment lag period," the cooling capacity of the chiller cannot immediately match the rapidly changing heat load of the machine tool. This can easily lead to significant fluctuations in the temperature of the cooling medium (overshoot or undershoot), making it impossible to achieve rapid temperature control. Summary of the Invention
[0005] The main objective of this invention is to provide a temperature control method for a machine tool cooling system, a machine tool cooling system, and a machine tool, in order to solve the problem in the prior art that the outlet water temperature of a machine tool cooler is prone to large fluctuations during the temperature adjustment process, making it difficult to maintain a constant water temperature.
[0006] To achieve the above objectives, according to one aspect of the present invention, a temperature control method for a machine tool cooling system is provided. The machine tool cooling system has a conventional flow path through which the compressor is connected to the evaporator via a condenser and a first electronic expansion valve, and a bypass flow path through which the compressor is connected to the evaporator via a second electronic expansion valve. The temperature control method includes: Step S1: controlling the conventional flow path to open, obtaining the time point at which the machine tool enters the target load condition, and sending a load signal containing the current heat load characterization value Q and the target heat load characterization value Q' to the cooling system during a first preset time period T before the time point; Step S2: obtaining the target operating frequency H' of the compressor when the machine tool enters the target load condition based on the current heat load characterization value Q, the target heat load characterization value Q', and the current operating frequency H of the compressor; Step S3: determining the adjustment timing for adjusting the compressor's operating frequency from the current operating frequency H to the target operating frequency H' based on the relationship between the target heat load characterization value Q' and the current heat load characterization value Q, and controlling the bypass flow path to open while adjusting the compressor's operating frequency until the compressor's operating frequency is adjusted to the target operating frequency H'.
[0007] Furthermore, based on the current heat load characterization value Q, the target heat load characterization value Q', and the compressor's current operating frequency H, the target operating frequency H' of the compressor when the machine tool enters the target load condition is obtained, including: according to the formula: H' = (Q') / (Q') H) / Q, the target operating frequency H' of the compressor is calculated.
[0008] Further, in step S3, the timing for adjusting the compressor's operating frequency from the current operating frequency H to the target operating frequency H' is determined based on the relationship between the target heat load characterization value Q' and the current heat load characterization value Q. This includes: if the target heat load characterization value Q' is greater than the current heat load characterization value Q, then timing begins when the compressor receives the load signal, and the compressor's operating frequency is adjusted after a second preset time period T'; the second preset time period T' is less than the first preset time period T; if the target heat load characterization value Q' is less than the current heat load characterization value Q, then the compressor's operating frequency is adjusted when the machine tool's heat load characterization value is at the target heat load characterization value Q'.
[0009] Furthermore, the first preset time period T is 3~5 min; and / or, in step S3, the second preset time period T' is obtained by: according to the formula: T'=T-(H'-H) / n; where n is the frequency adjustment rate of the compressor and satisfies: 1Hz / s≤n≤5Hz / s.
[0010] Furthermore, in step S3, the method of controlling the opening of the bypass flow path while adjusting the operating frequency of the compressor includes: when the operating frequency of the compressor is adjusted, the second electronic expansion valve is opened simultaneously, and the opening control strategy of the second electronic expansion valve is determined according to the relationship between the target heat load characterization value Q' and the current heat load characterization value Q.
[0011] Furthermore, in step S3, the method of controlling the opening of the bypass flow path while adjusting the operating frequency of the compressor includes: simultaneously opening the second electronic expansion valve while adjusting the operating frequency of the compressor, and controlling the opening adjustment rate of the second electronic expansion valve to be linearly proportional to the frequency adjustment rate of the compressor.
[0012] Furthermore, the opening control strategy of the second electronic expansion valve is determined based on the relationship between the target heat load characterization value Q' and the current heat load characterization value Q, including: if the target heat load characterization value Q' is greater than the current heat load characterization value Q, the second electronic expansion valve gradually increases from zero opening and closes when the compressor's operating frequency increases to the target operating frequency H'; if the target heat load characterization value Q' is less than the current heat load characterization value Q, the second electronic expansion valve gradually decreases from a preset opening value B' and closes when the compressor's operating frequency decreases to the target operating frequency H'.
[0013] Furthermore, when the target heat load characterization value Q' is greater than the current heat load characterization value Q, the method of gradually increasing the opening of the second electronic expansion valve from zero includes: controlling the opening of the second electronic expansion valve to gradually increase from zero in B steps per Hertz, where B is the adjustment step number of the second electronic expansion valve and satisfies: 5≤B≤15.
[0014] Furthermore, when the target heat load characterization value Q' is less than the current heat load characterization value Q, the method for obtaining the preset opening value B' includes: according to the formula B'=(Q-Q') B yields the following: where B is the adjustment step number of the second electronic expansion valve and satisfies: 5≤B≤15.
[0015] Furthermore, when the target heat load characterization value Q' is less than the current heat load characterization value Q, the method of gradually reducing the second electronic expansion valve with a preset opening value B' includes: controlling the opening of the second electronic expansion valve to gradually decrease from the preset opening value B' at B steps per Hertz, where B is the adjustment step number of the second electronic expansion valve and satisfies: 5≤B≤15.
[0016] Furthermore, if the target heat load characterization value Q' is greater than the current heat load characterization value Q, the temperature control method also includes step S4 after step S3: when the compressor's operating frequency increases to the target operating frequency H', the bypass flow path is closed, the liquid outlet temperature value of the evaporator is obtained, and the relationship between the liquid outlet temperature value and the preset temperature threshold is used to determine whether to reopen the bypass flow path or increase the compressor's operating frequency.
[0017] Furthermore, in step S4, the method for determining whether to reopen the bypass flow path or increase the operating frequency of the compressor based on the relationship between the outlet temperature value and the preset temperature threshold includes: if the outlet temperature value is less than the preset temperature threshold, then reopen the bypass flow path; if the outlet temperature value is greater than the preset temperature threshold, then increase the operating frequency of the compressor.
[0018] According to another aspect of the present invention, a machine tool cooling system is provided, comprising: a compressor having an exhaust end and an intake end; a condenser communicating with the exhaust end of the compressor; an evaporator for exchanging heat with a coolant; a first electronic expansion valve connected between the condenser and the evaporator; a second electronic expansion valve connected between the exhaust end of the compressor and the evaporator; and a controller electrically connected to the compressor, the first electronic expansion valve, and the second electronic expansion valve, the controller being configured to perform the temperature control method of the machine tool cooling system as described above.
[0019] According to another aspect of the present invention, a machine tool is provided, including the machine tool cooling system described above.
[0020] By applying the technical solution of this invention, when the heat load of the machine tool remains constant, the conventional flow path is opened. During the first preset time period T before the machine tool enters the target load condition (high load or low load), the machine tool sends a load signal to the cooling system containing the current heat load characterization value Q and the target heat load characterization value Q'. The cooling system calculates the target operating frequency H' based on the current heat load characterization value Q, the target heat load characterization value Q', and the current operating frequency H of the compressor. Subsequently, while adjusting the operating frequency of the compressor, the bypass flow path is opened (i.e., the second electronic expansion valve is opened), allowing high-temperature and high-pressure gas to enter the evaporator through the bypass flow path. The hot gas bypass technology is used to offset the cooling capacity fluctuation caused by the compressor frequency change, thereby maintaining the outlet water temperature (coolant temperature) of the evaporator constant during the compressor frequency transition until the compressor frequency reaches the target operating frequency H'. This achieves precise temperature control during the sudden change of machine tool load, thus solving the problem in the prior art where the outlet water temperature of the machine tool cooler is prone to large fluctuations during the temperature adjustment process, making it difficult to maintain a constant water temperature. Meanwhile, by utilizing the heat neutralization mechanism of bypass hot gas and conventional refrigerant during compressor frequency transition, a dynamic balance of cooling output is achieved, effectively avoiding significant water temperature fluctuations caused by compressor frequency increase or decrease lag, ensuring that the evaporator outlet water temperature remains constant, thereby guaranteeing the machining accuracy of the machine tool during high and low load switching. Attached Figure Description
[0021] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:
[0022] Figure 1 A schematic diagram of an embodiment of a machine tool cooling system according to the present invention is shown;
[0023] Figure 2 It shows Figure 1 Logic diagram of the temperature control method of the cooling system when the machine tool enters a high-speed or high-load working state;
[0024] Figure 3 It shows Figure 1 The logic diagram of the temperature control method of the cooling system when the machine tool enters a low-load working state.
[0025] The above figures include the following reference numerals:
[0026] 10. Compressor;
[0027] 20. Condenser;
[0028] 30. First electronic expansion valve;
[0029] 40. Evaporator;
[0030] 50. Second electronic expansion valve;
[0031] 60. Pump;
[0032] 70. Coolant storage tank;
[0033] 81. From the machine tool return port; 82. To the machine tool outlet. Detailed Implementation
[0034] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.
[0035] It should be noted that, unless otherwise specified, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.
[0036] In this invention, unless otherwise stated, directional terms such as "up" and "down" are generally used in relation to the direction shown in the accompanying drawings, or in relation to the vertical, perpendicular, or gravitational direction; similarly, for ease of understanding and description, "left" and "right" are generally used in relation to the left and right shown in the accompanying drawings; "inner" and "outer" refer to the inner and outer contours of each component itself, but the above directional terms are not intended to limit this invention.
[0037] To address the problem in the prior art that the outlet water temperature of machine tool coolers is prone to significant fluctuations during the temperature adjustment process, making it difficult to maintain a constant water temperature, this application provides a temperature control method for a machine tool cooling system, a machine tool cooling system, and a machine tool.
[0038] like Figures 1 to 3 As shown, the machine tool cooling system has a conventional flow path where the compressor 10 is connected to the evaporator 40 through the condenser 20 and the first electronic expansion valve 30, and a bypass flow path where the compressor 10 is connected to the evaporator 40 through the second electronic expansion valve 50. The temperature control method of the machine tool cooling system includes:
[0039] Step S1: Control the opening of the normal flow path, obtain the time point when the machine tool enters the target load condition, and send a load signal containing the current heat load characterization value Q and the target heat load characterization value Q' to the cooling system during the first preset time period T before the time point;
[0040] Step S2: Based on the current heat load characterization value Q, the target heat load characterization value Q', and the current operating frequency H of the compressor 10, obtain the target operating frequency H' of the compressor 10 when the machine tool enters the target load condition;
[0041] Step S3: Based on the relationship between the target heat load characterization value Q' and the current heat load characterization value Q, determine the timing for adjusting the operating frequency of compressor 10 from the current operating frequency H to the target operating frequency H', and control the bypass flow path to open while adjusting the operating frequency of compressor 10 until the operating frequency of compressor 10 is adjusted to the target operating frequency H'.
[0042] By applying the technical solution of this embodiment, when the heat load of the machine tool remains constant, the conventional flow path is opened. During the first preset time period T before the machine tool enters the target load condition (high load or low load), the machine tool sends a load signal to the cooling system containing the current heat load characterization value Q and the target heat load characterization value Q'. The cooling system calculates the target operating frequency H' based on the current heat load characterization value Q, the target heat load characterization value Q', and the current operating frequency H of the compressor. Then, while adjusting the operating frequency of the compressor, the bypass flow path is opened (i.e., the second electronic expansion valve 50 is opened), allowing high-temperature and high-pressure gas to enter the evaporator 40 through the bypass flow path. The hot gas bypass technology is used to offset the cooling capacity fluctuation caused by the compressor frequency change, thereby maintaining the outlet water temperature (coolant temperature) of the evaporator 40 constant during the compressor frequency transition until the compressor frequency reaches the target operating frequency H'. This achieves precise temperature control during the sudden change of machine tool load, thereby solving the problem in the prior art where the outlet water temperature of the machine tool cooler is prone to large fluctuations during the temperature adjustment process, making it difficult to maintain a constant water temperature. Meanwhile, by utilizing the heat neutralization mechanism of bypass hot gas and conventional refrigerant during compressor frequency transition, a dynamic balance of cooling output is achieved, effectively avoiding significant water temperature fluctuations caused by compressor frequency increase or decrease lag, ensuring that the evaporator outlet water temperature remains constant, thereby guaranteeing the machining accuracy of the machine tool during high and low load switching.
[0043] In this embodiment, a machine tool cooling control scheme with an advance feedback mechanism is proposed. Through the communication between the machine tool program and the corresponding cooling machine program, when the machine tool is about to operate at high power or high speed in the preset program, the cooling machine is adjusted and frequency increased in advance. During the frequency increase process, the bypass flow path is adjusted to keep the outlet water temperature of the evaporator 40 constant. At the moment when the machine tool operates at high power, the bypass is closed to achieve the function of instantaneous rapid temperature control. Through the advance feedback mechanism and adjustment between the machine tool and the cooling system, the water temperature is kept constant to maintain the machining accuracy of the machine tool.
[0044] In this embodiment, the flow direction of the cooling medium in the conventional flow path is as follows: the high-temperature, high-pressure gas discharged from the exhaust end of the compressor 10 sequentially enters the condenser 20, the first electronic expansion valve 30, and the evaporator 40; the liquid refrigerant returning from the evaporator 40 then enters the suction end of the compressor 10. The flow direction of the cooling medium in the bypass flow path is as follows: the high-temperature, high-pressure gas discharged from the exhaust end of the compressor 10 sequentially enters the second electronic expansion valve 50 and the evaporator 40; the liquid refrigerant returning from the evaporator 40 then enters the suction end of the compressor 10.
[0045] In this embodiment, the heat exchange flow path of the coolant is as follows: it enters the evaporator 40, pump 60 and coolant storage tank 70 sequentially from the machine tool return port 81 and then flows to the machine tool outlet 82 to cool the machine tool.
[0046] In this embodiment, the target operating frequency H' of the compressor 10 when the machine tool enters the target load condition is obtained based on the current heat load characterization value Q, the target heat load characterization value Q', and the current operating frequency H of the compressor 10, including:
[0047] According to the formula: H' = (Q') H) / Q, the target operating frequency H' of compressor 10 is calculated.
[0048] Specifically, based on the machine tool's current heat load characterization value Q, the target heat load characterization value Q', and the compressor's current operating frequency H, the formula H' = (Q') is used. The H) / Q linear mapping calculates the target operating frequency H' required by compressor 10 when the machine tool enters the target load condition, achieving a precise correspondence between compressor frequency and machine tool thermal load. In this way, by establishing a linear proportional relationship between the thermal load characterization value and compressor frequency, the target operating frequency of the compressor can be quickly and accurately predicted and set according to changes in machine tool operating conditions, ensuring that the cooling capacity of the cooling system matches the changes in machine tool thermal load, and providing an accurate frequency adjustment basis for subsequent precise temperature control.
[0049] In this embodiment, in step S3, determining the timing for adjusting the operating frequency of compressor 10 from the current operating frequency H to the target operating frequency H' based on the relationship between the target heat load characterization value Q' and the current heat load characterization value Q includes:
[0050] If the target heat load characterization value Q' is greater than the current heat load characterization value Q, then the compressor 10 starts timing when it receives the load signal, and adjusts the operating frequency of the compressor 10 after the second preset time period T'; the second preset time period T' is less than the first preset time period T;
[0051] If the target heat load characterization value Q' is less than the current heat load characterization value Q, then the operating frequency of the compressor 10 is adjusted when the heat load characterization value of the machine tool is at the target heat load characterization value Q'.
[0052] Specifically, when the target heat load characterization value Q' is greater than the current heat load characterization value Q, the compressor 10 starts timing after receiving the load signal. After a second preset time period T' shorter than the first preset time period T, it starts frequency increase regulation to reserve sufficient adjustment time. When the target heat load characterization value Q' is less than the current heat load characterization value Q, frequency decrease regulation is started only when the actual heat load of the machine tool drops to the target value Q', ensuring that the frequency decrease action is synchronized with the actual low load condition. In this way, a strategy of advance prediction and shortening the waiting time is adopted for high load conditions to compensate for the risk of water temperature overshoot caused by the compressor frequency increase lag, ensuring that the frequency adjustment is completed before the high load of the machine tool arrives. For low load conditions, an actual load triggering strategy is adopted to avoid excessive cooling capacity or excessively low water temperature caused by premature frequency decrease due to prediction deviation. Thus, the compressor frequency and machine tool heat load can be accurately matched in both operating conditions, maintaining water temperature stability.
[0053] Optionally, the first preset time period T is 3~5 min; and / or, in step S3, the second preset time period T' is obtained by using the formula: T'=T-(H'-H) / n; where n is the frequency adjustment rate of the compressor 10 and satisfies: 1Hz / s≤n≤5Hz / s. Thus, when the machine tool's heat load increases, the controller calculates the second preset time period T' based on the first preset time period T (3~5 min) and the compressor frequency adjustment rate n (1~5Hz / s) using the formula T'=T-(H'-H) / n, and waits for T' time after receiving the load signal before starting the compressor to increase its frequency, ensuring that the compressor frequency reaches the target operating frequency H' before the machine tool enters a high load state.
[0054] In this embodiment, the first preset time period T is 3-5 minutes. In step S3, the second preset time period T' is obtained by using the formula: T'=T-(H'-H) / n; where n is the frequency adjustment rate of the compressor 10 and satisfies: 1Hz / s≤n≤5Hz / s. Thus, by dynamically calculating the precise advance adjustment time T', the physical time lag required for the compressor to rise from the current frequency H to the target frequency H' is eliminated, achieving perfect synchronization between "cooling demand" and "cooling supply" on the time axis. This ensures that the cooling system has sufficient cooling capacity during high-load cutting of the machine tool, thereby preventing the water temperature from rising due to response delay and ensuring machining accuracy.
[0055] In this embodiment, the method of controlling the bypass flow path to open while adjusting the operating frequency of the compressor 10 in step S3 includes:
[0056] When starting to adjust the operating frequency of the compressor 10, the second electronic expansion valve 50 is opened synchronously, and an opening control strategy for the second electronic expansion valve 50 is determined according to the relationship between the target heat load characterization value Q' and the current heat load characterization value Q.
[0057] Specifically, when the compressor 10 starts to adjust its operating frequency, the second electronic expansion valve 50 is opened synchronously to establish a bypass flow path, and differential control is performed according to the magnitude relationship between the target heat load characterization value Q' and the current heat load characterization value Q: when Q' > Q, during the frequency rising process of the compressor, the opening degree of the second electronic expansion valve 50 gradually decreases as the compressor frequency increases to offset the increase in cooling capacity, until the frequency stabilizes and then the bypass flow path is closed (the second electronic expansion valve 50 is closed); when Q' < Q, during the frequency decreasing process of the compressor, the opening degree of the second electronic expansion valve 50 gradually increases as the compressor frequency decreases to compensate for the decrease in cooling capacity, until the frequency stabilizes and then the bypass flow path is gradually closed (the second electronic expansion valve 50 is closed). In this way, through the linkage adjustment of the bypass flow path and the frequency conversion of the compressor, the fluctuation of cooling capacity is counteracted in real time during the dynamic change of the compressor frequency, realizing the smooth transition of cooling output, effectively avoiding large water temperature jitter caused by the step change of the compressor frequency, and ensuring that the outlet water temperature is always constant during the load switching process of the machine tool.
[0058] Optionally, in step S3, the method for controlling the opening of the bypass flow path while adjusting the operating frequency of the compressor 10 comprises:
[0059] When adjusting the operating frequency of the compressor 10, the second electronic expansion valve 50 is opened synchronously, and the opening adjustment rate of the second electronic expansion valve 50 is controlled to have a linear proportional relationship with the frequency adjustment rate of the compressor 10.
[0060] Specifically, during the frequency adjustment process of the compressor 10, the adjustment action of the second electronic expansion valve 50 is started synchronously, and the opening change rate of the second electronic expansion valve 50 is controlled to maintain a linear proportional relationship with the frequency change rate of the compressor 10, so that the change of the bypass flow rate and the change of the cooling capacity of the compressor are synchronously matched in real time. In this way, by establishing a linear linkage mechanism between the opening of the bypass valve and the frequency of the compressor, dynamic balance compensation for cooling output is realized, effectively eliminating water temperature fluctuations caused by sudden changes in cooling capacity during the frequency conversion process of the compressor, and ensuring continuous constant coolant temperature during frequency adjustment.
[0061] In this embodiment, determining the opening control strategy for the second electronic expansion valve 50 according to the relationship between the target heat load characterization value Q' and the current heat load characterization value Q comprises:
[0062] If the target heat load characterization value Q' is greater than the current heat load characterization value Q, the second electronic expansion valve 50 gradually increases from zero opening, and closes when the operating frequency of the compressor 10 increases to the target operating frequency H'.
[0063] If the target heat load characterization value Q' is less than the current heat load characterization value Q, the second electronic expansion valve 50 gradually decreases at a preset opening value B', and closes when the operating frequency of the compressor 10 decreases to the target operating frequency H'.
[0064] Specifically, when the target heat load value Q' is greater than the current heat load value Q, the second electronic expansion valve 50 gradually increases its opening from 0 to introduce hot gas bypass to offset the excess cooling capacity caused by the frequency increase. The bypass is closed once the compressor frequency reaches the target frequency H'. When the target heat load value Q' is less than the current heat load value Q, the second electronic expansion valve 50 gradually decreases its opening from a preset degree B' to compensate for the insufficient cooling capacity caused by the frequency decrease. The bypass is completely closed once the compressor frequency drops to the target frequency H'. In this way, the bypass valve's operating logic is dynamically adjusted according to the direction of load increase or decrease, precisely matching the cooling capacity changes during compressor frequency transitions. The thermal effect of hot gas bypass balances cooling capacity fluctuations, ensuring the stability of the outlet water temperature throughout the load switching process. This avoids water temperature overshoot or undershoot caused by frequency regulation lag, thus guaranteeing the machining accuracy of the machine tool.
[0065] In this embodiment, the method for gradually increasing the opening of the second electronic expansion valve 50 from zero when the target heat load characterization value Q' is greater than the current heat load characterization value Q includes:
[0066] The opening of the second electronic expansion valve 50 is controlled to gradually increase from zero in steps B per hertz, where B is the number of adjustment steps of the second electronic expansion valve 50 and satisfies: 5≤B≤15.
[0067] Specifically, when the target heat load characterization value Q' is greater than the current heat load characterization value Q, the second electronic expansion valve 50 is controlled to start from the closed state. As the operating frequency of the compressor 10 increases by 1Hz, the opening degree of the second electronic expansion valve 50 increases by B steps (where B is an integer value between 5 and 15) until the compressor frequency reaches the target operating frequency H'. In this way, by setting a fixed number of steps B for the opening increment of the bypass valve for every 1Hz change in compressor frequency, a linear and precise match between the bypass hot gas flow and the increase in compressor cooling capacity is achieved. This effectively offsets the impact of the rapid increase in cooling capacity on water temperature during compressor frequency increase, ensuring a constant coolant temperature during high load switching and maintaining the machining accuracy of the machine tool.
[0068] In this embodiment, when the target heat load characterization value Q' is less than the current heat load characterization value Q, the method for obtaining the preset opening value B' includes:
[0069] According to the formula B' = (Q - Q') B yields the following result: where B is the adjustment step number of the second electronic expansion valve 50 and satisfies: 5≤B≤15.
[0070] Specifically, when the target heat load characterization value Q' is less than the current heat load characterization value Q, the controller, based on the difference between the current heat load and the target heat load (Q-Q') and the bypass valve adjustment step number B (5≤B≤15), uses the formula B'=(Q-Q'). B calculates the initial preset opening value B' and quickly adjusts the second electronic expansion valve 50 to this opening value B' before the compressor starts to reduce its frequency. Then, as the compressor frequency decreases, the bypass valve is gradually closed until it is shut off. In this way, by dynamically calculating the initial bypass opening value B' based on the heat load difference, the cooling capacity gap can be quickly compensated by hot gas bypass at the moment when the cooling capacity drops sharply due to the compressor frequency reduction, preventing the water temperature from rising rapidly due to insufficient cooling capacity. Through the strategy of "bypass compensation first, then frequency conversion adjustment", high-precision constant water temperature control is achieved during low-load switching.
[0071] In this embodiment, the method of gradually reducing the second electronic expansion valve 50 by a preset opening value B' when the target heat load characterization value Q' is less than the current heat load characterization value Q includes:
[0072] The opening degree of the second electronic expansion valve 50 is controlled to gradually decrease from the preset opening degree value B' in B steps per hertz, where B is the adjustment step number of the second electronic expansion valve 50 and satisfies: 5≤B≤15.
[0073] Specifically, when the target heat load characterization value Q' is less than the current heat load characterization value Q, based on the second electronic expansion valve 50 being adjusted to the initial preset opening degree B', as the compressor 10 operating frequency decreases by 1Hz, the opening degree of the second electronic expansion valve 50 is reduced by B steps (where B is an integer value between 5 and 15), until the compressor frequency drops to the target operating frequency H', at which point the bypass valve is completely closed. In this way, by establishing a fixed step increment B for the bypass valve to close for every 1Hz decrease in compressor frequency, a linear synchronous match is achieved between the bypass hot gas flow and the reduction in compressor cooling capacity. This avoids insufficient cooling capacity and water temperature rise caused by excessively rapid compressor frequency reduction, ensuring a smooth transition and constant coolant temperature during low-load switching, and guaranteeing the machining accuracy of the machine tool.
[0074] In this embodiment, if the target heat load characterization value Q' is greater than the current heat load characterization value Q, the temperature control method further includes step S4 after step S3:
[0075] When the operating frequency of compressor 10 increases to the target operating frequency H', the bypass flow path is closed, the liquid outlet temperature value of evaporator 40 is obtained, and the relationship between the liquid outlet temperature value and the preset temperature threshold is used to determine whether to reopen the bypass flow path or increase the operating frequency of compressor 10.
[0076] Specifically, when the compressor 10's operating frequency increases to the target operating frequency H' and the bypass flow path is closed, the outlet temperature of the evaporator 40 is monitored in real time and compared with a preset temperature threshold. If the outlet temperature is lower than the preset threshold, it indicates that the cooling capacity is excessive, and the bypass flow path is reopened to recover some of the cooling capacity. If the outlet temperature is still higher than the preset threshold, it indicates that the cooling capacity is insufficient at the current frequency, and the operating frequency of the compressor 10 is further increased until the temperature meets the requirements. In this way, the actual cooling effect after frequency conversion regulation is finely corrected through a closed-loop feedback mechanism. By using bypass flow path fine-tuning or further frequency increase, static errors are eliminated, ensuring that the outlet water temperature can be accurately and stably maintained within the set range under high machine tool load conditions. This prevents water temperature runaway caused by model calculation deviations or operating condition fluctuations, thereby ensuring high-precision machining requirements.
[0077] In this embodiment, the method for determining whether to reopen the bypass flow path or increase the operating frequency of the compressor 10 based on the relationship between the outlet temperature value and the preset temperature threshold in step S4 includes:
[0078] If the outlet temperature is lower than the preset temperature threshold, the bypass flow path will be reopened.
[0079] If the outlet temperature is greater than the preset temperature threshold, the operating frequency of compressor 10 will be increased.
[0080] Specifically, after the compressor 10 reaches the target frequency H' and the bypass path is closed, the outlet temperature of the evaporator 40 is acquired in real time and compared with a preset temperature threshold. If the outlet temperature is less than the preset temperature threshold, it indicates that the current cooling capacity is excessive, so the bypass path is reopened to introduce hot air to offset the excess cooling capacity. If the outlet temperature is greater than the preset temperature threshold, it indicates that the current cooling capacity is insufficient, so the operating frequency of the compressor 10 is increased to improve the cooling output. In this way, through the closed-loop feedback mechanism of the outlet temperature, the frequency conversion control based on heat load prediction is corrected in real time, effectively eliminating static temperature deviations caused by model errors or operating condition disturbances, ensuring the precise constantness of the outlet water temperature under steady-state high load, and further guaranteeing the consistency of machine tool processing accuracy.
[0081] like Figure 1As shown, this application also provides a machine tool cooling system, including a compressor 10, a condenser 20, an evaporator 40, a first electronic expansion valve 30, and a second electronic expansion valve 50. The compressor 10 has a discharge end and a suction end. The condenser 20 is connected to the discharge end of the compressor 10. The evaporator 40 is used for heat exchange with coolant. The first electronic expansion valve 30 is connected between the condenser 20 and the evaporator 40. The second electronic expansion valve 50 is connected between the discharge end of the compressor 10 and the evaporator 40. A controller is electrically connected to the compressor 10, the first electronic expansion valve 30, and the second electronic expansion valve 50, and the controller is configured to execute the temperature control method of the machine tool cooling system described above.
[0082] In this embodiment, the machine tool cooling system comprises a compressor 10, a condenser 20, an evaporator 40, and a first electronic expansion valve 30 forming the main refrigeration circuit. A second electronic expansion valve 50 connects the exhaust end of the compressor 10 to the evaporator 40, forming a hot gas bypass circuit. The controller is electrically connected to each component and, by executing the aforementioned temperature control method, coordinates the adjustment of the compressor 10 frequency and the bypass valve opening when the machine tool load changes, achieving dynamic balance of cooling capacity. Thus, the hardware architecture described above in this embodiment, combined with the control strategy, can respond to machine tool load fluctuations in real time. By using the hot gas bypass mechanism, it can offset the cooling capacity fluctuations during compressor frequency conversion, ensuring a highly constant coolant temperature during load switching and steady-state operation, thereby guaranteeing the machining accuracy of the machine tool. Simultaneously, it achieves energy-saving operation through precise energy matching.
[0083] Specifically, the machine tool cooling system has a conventional flow path in which the compressor 10 is connected to the evaporator 40 through the condenser 20 and the first electronic expansion valve 30, and a bypass flow path in which the compressor 10 is connected to the evaporator 40 through the second electronic expansion valve 50.
[0084] In this embodiment, when the machine tool is in normal working condition, only the normal flow path is opened, and the frequency rise and fall is controlled by water temperature. This special adjustment is only performed when there is a sudden large load change.
[0085] During machine tool operation, the system continuously monitors its own operating status. When it detects that it is about to enter high-speed or high-load operation, it sends a high-load signal to the cooling system at a time interval T in advance, simultaneously sending the current heat load characterization value Q1 and the corresponding target heat load characterization value Q1' for high load or high speed. After receiving the load signal, the cooling system reads its current compressor frequency H1 and calculates the required compressor frequency H1' for high load operation of the machine tool = (Q1') / (Q1'). H1) / Q1. Since compressor adjustment requires time, the required adjustment time is calculated as t = (H1' - H1) / n; (n is the compressor adjustment rate, usually set to 1~5Hz / s based on compressor specifications). After (Tt) time, when the cooler receives a high load or high speed signal, the compressor begins frequency increase adjustment at a rate of n. Simultaneously with the frequency increase, the second electronic expansion valve 50 opens. For every 1Hz increase in compressor frequency, the bypass electronic expansion valve opens by B steps (B is a matching value developed during cooler development; the increase in cooling capacity for every 1Hz increase corresponds to the decrease in cooling capacity for every B steps the bypass valve opens; based on experience, B is usually set between 5 and 20). This ensures that the water temperature does not fluctuate during compressor frequency increase. When the compressor reaches H1', it indicates that the machine tool has entered a high-load working state. At this time, the second electronic expansion valve closes, and the cooler outputs high-frequency, high-capacity cooling, ensuring that the water temperature does not fluctuate. T is used to ensure that the machine tool has enough adjustment time. Usually, it takes 2 to 3 minutes for the cooling machine to be loaded to full frequency, so T is usually set to 3 to 5 minutes.
[0086] Similarly, when a machine tool suddenly switches from a high-load operating state to a low-load operating state, a stable water temperature is also required. Specifically, when the machine tool suddenly switches from a high-load to a low-load state, a low-load signal is sent in advance by time T, along with the current heat load characterization value Q2 and the corresponding target heat load characterization value Q2' at the low load. Afterwards, the cooling system reads its current compressor frequency H2 and calculates the required compressor frequency H2' = (Q2') at the corresponding low load of the machine tool. Calculate the required opening degree B' of the second electronic expansion valve under low load at the current frequency: B' = (H2 - H2'). B. When the machine tool switches to low-load operation, the opening of the second electronic expansion valve is simultaneously adjusted to B' to instantly reduce the cooling system output and ensure a constant water temperature. Finally, as the machine tool enters low-load operation, the compressor begins frequency reduction regulation at a rate of n. For every 1Hz reduction in compressor frequency, the second electronic expansion valve closes step B, ensuring that the cooling system output remains constant and the water temperature is maintained. During this process, the bypass path mixes the high-temperature exhaust gas with the throttled low-temperature liquid refrigerant, thus reducing cooling output and achieving "ineffective work."
[0087] This application also provides a machine tool (not shown) including the machine tool cooling system described above.
[0088] As can be seen from the above description, the embodiments of the present invention achieve the following technical effects:
[0089] When the machine tool's heat load remains constant, the conventional flow path is opened. During the first preset time period T before the machine tool enters the target load condition (high load or low load), the machine tool sends a load signal to the cooling system containing the current heat load characterization value Q and the target heat load characterization value Q'. The cooling system calculates the target operating frequency H' based on the current heat load characterization value Q, the target heat load characterization value Q', and the compressor's current operating frequency H. Then, while adjusting the compressor's operating frequency, the bypass flow path is opened (i.e., the second electronic expansion valve is opened), allowing high-temperature and high-pressure gas to enter the evaporator through the bypass flow path. The hot gas bypass technology is used to offset the cooling capacity fluctuations caused by the compressor frequency change, thereby maintaining a constant evaporator outlet water temperature (coolant temperature) during the compressor frequency transition period until the compressor frequency reaches the target operating frequency H'. This achieves precise temperature control during the machine tool load change process, thus solving the problem in the prior art where the outlet water temperature of the machine tool cooler is prone to large fluctuations during the temperature adjustment process, making it difficult to maintain a constant water temperature. Meanwhile, by utilizing the heat neutralization mechanism of bypass hot gas and conventional refrigerant during compressor frequency transition, a dynamic balance of cooling output is achieved, effectively avoiding significant water temperature fluctuations caused by compressor frequency increase or decrease lag, ensuring that the evaporator outlet water temperature remains constant, thereby guaranteeing the machining accuracy of the machine tool during high and low load switching.
[0090] Obviously, the embodiments described above are merely some, not all, embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort should fall within the scope of protection of the present invention.
[0091] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.
[0092] It should be noted that the terms "first," "second," etc., used in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented in sequences other than those illustrated or described herein.
[0093] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.
Claims
1. A temperature control method for a machine tool cooling system, characterized in that, The machine tool cooling system has a conventional flow path in which the compressor (10) is connected to the evaporator (40) through the condenser (20) and the first electronic expansion valve (30), and a bypass flow path in which the compressor (10) is connected to the evaporator (40) through the second electronic expansion valve (50). The temperature control method includes: Step S1: Control the opening of the conventional flow path, obtain the time point when the machine tool enters the target load condition, and send a load signal containing the current heat load characterization value Q and the target heat load characterization value Q' to the cooling system during the first preset time period T before the time point; Step S2: Based on the current heat load characterization value Q, the target heat load characterization value Q', and the current operating frequency H of the compressor (10), obtain the target operating frequency H' of the compressor (10) when the machine tool enters the target load condition; Step S3: Based on the relationship between the target heat load characterization value Q' and the current heat load characterization value Q, determine the timing for adjusting the operating frequency of the compressor (10) from the current operating frequency H to the target operating frequency H', and control the bypass flow path to open while adjusting the operating frequency of the compressor (10) until the operating frequency of the compressor (10) is adjusted to the target operating frequency H'.
2. The temperature control method for a machine tool cooling system according to claim 1, characterized in that, The step of obtaining the target operating frequency H' of the compressor (10) when the machine tool enters the target load condition based on the current heat load characterization value Q, the target heat load characterization value Q', and the current operating frequency H of the compressor (10) includes: According to the formula: H' = (Q') H) / Q, the target operating frequency H' of the compressor (10) is calculated.
3. The temperature control method for a machine tool cooling system according to claim 1, characterized in that, In step S3, determining the timing for adjusting the operating frequency of the compressor (10) from the current operating frequency H to the target operating frequency H' based on the relationship between the target heat load characterization value Q' and the current heat load characterization value Q includes: If the target heat load characterization value Q' is greater than the current heat load characterization value Q, then when the compressor (10) receives the load signal, the timing starts, and the operating frequency of the compressor (10) is adjusted after the second preset time period T'; the second preset time period T' is less than the first preset time period T; If the target heat load characterization value Q' is less than the current heat load characterization value Q, then the operating frequency of the compressor (10) is adjusted when the heat load characterization value of the machine tool is at the target heat load characterization value Q'.
4. The temperature control method for the machine tool cooling system according to claim 3, characterized in that, The first preset time period T is 3~5 minutes; and / or, in step S3, the method for obtaining the second preset time period T' is as follows: According to the formula: T'=T-(H'-H) / n; where n is the frequency regulation rate of the compressor (10) and satisfies: 1Hz / s≤n≤5Hz / s.
5. The temperature control method for a machine tool cooling system according to claim 1, characterized in that, In step S3, the method of controlling the opening of the bypass flow path while adjusting the operating frequency of the compressor (10) includes: When the operating frequency of the compressor (10) is adjusted, the second electronic expansion valve (50) is opened synchronously, and the opening control strategy of the second electronic expansion valve (50) is determined according to the relationship between the target heat load characterization value Q' and the current heat load characterization value Q.
6. The temperature control method for a machine tool cooling system according to claim 1, characterized in that, In step S3, the method of controlling the opening of the bypass flow path while adjusting the operating frequency of the compressor (10) includes: When adjusting the operating frequency of the compressor (10), the second electronic expansion valve (50) is opened simultaneously, and the opening adjustment rate of the second electronic expansion valve (50) is controlled to be linearly proportional to the frequency adjustment rate of the compressor (10).
7. The temperature control method for a machine tool cooling system according to claim 5, characterized in that, The step of determining the opening control strategy of the second electronic expansion valve (50) based on the relationship between the target heat load characterization value Q' and the current heat load characterization value Q includes: If the target heat load characterization value Q' is greater than the current heat load characterization value Q, the second electronic expansion valve (50) gradually increases from zero opening, and closes the second electronic expansion valve (50) when the operating frequency of the compressor (10) increases to the target operating frequency H'. If the target heat load characterization value Q' is less than the current heat load characterization value Q, the second electronic expansion valve (50) gradually decreases by a preset opening value B', and closes the second electronic expansion valve (50) when the operating frequency of the compressor (10) decreases to the target operating frequency H'.
8. The temperature control method for a machine tool cooling system according to claim 7, characterized in that, When the target heat load characterization value Q' is greater than the current heat load characterization value Q, the method for gradually increasing the opening of the second electronic expansion valve (50) from zero includes: The opening of the second electronic expansion valve (50) is controlled to gradually increase from zero in steps B per hertz, where B is the adjustment step number of the second electronic expansion valve (50) and satisfies: 5≤B≤15.
9. The temperature control method for a machine tool cooling system according to claim 7, characterized in that, When the target heat load characterization value Q' is less than the current heat load characterization value Q, the method for obtaining the preset opening value B' includes: According to the formula B' = (Q - Q') B yields the following result: where B is the adjustment step number of the second electronic expansion valve (50) and satisfies: 5≤B≤15.
10. The temperature control method for a machine tool cooling system according to claim 7, characterized in that, When the target heat load characterization value Q' is less than the current heat load characterization value Q, the method of gradually reducing the second electronic expansion valve (50) by a preset opening value B' includes: The opening degree of the second electronic expansion valve (50) is controlled to gradually decrease from the preset opening degree value B' in B steps per hertz, where B is the adjustment step number of the second electronic expansion valve (50) and satisfies: 5≤B≤15.
11. The temperature control method for a machine tool cooling system according to claim 1, characterized in that, If the target heat load characterization value Q' is greater than the current heat load characterization value Q, the temperature control method further includes step S4 following step S3: When the operating frequency of the compressor (10) increases to the target operating frequency H', the bypass flow path is closed, the outlet temperature value of the evaporator (40) is obtained, and the relationship between the outlet temperature value and the preset temperature threshold is used to determine whether to reopen the bypass flow path or increase the operating frequency of the compressor (10).
12. The temperature control method for a machine tool cooling system according to claim 11, characterized in that, In step S4, the method for determining whether to reopen the bypass flow path or increase the operating frequency of the compressor (10) based on the relationship between the outlet temperature value and the preset temperature threshold includes: If the outlet temperature is less than the preset temperature threshold, the bypass flow path will be reopened. If the outlet temperature is greater than the preset temperature threshold, the operating frequency of the compressor (10) will be increased.
13. A machine tool cooling system, characterized in that, include: The compressor (10) has an exhaust end and an intake end; A condenser (20) is connected to the exhaust end of the compressor (10); Evaporator (40), the evaporator (40) is used for heat exchange with coolant; A first electronic expansion valve (30) is connected between the condenser (20) and the evaporator (40); The second electronic expansion valve (50) is connected between the exhaust end of the compressor (10) and the evaporator (40); The controller is electrically connected to the compressor (10), the first electronic expansion valve (30) and the second electronic expansion valve (50), and is configured to perform the temperature control method of the machine tool cooling system as described in any one of claims 1 to 12.
14. A machine tool, characterized in that, Includes the machine tool cooling system as described in claim 13.