A constant temperature system with a cold water circulation system for a polyurethane injection machine and a method for regulating the same

Abstract

The application discloses a kind of polyurethane glue injection machine constant temperature systems with cold water circulation system and its regulation and control method, including glue injection machine ontology, raw material storage tank, constant temperature jacket, cold water circulation unit, heating unit, temperature detection unit, control unit and heat preservation unit.Constant temperature jacket is formed circulation cavity by being sleeved in raw material storage tank outside;Cold water circulation unit is by cold water tank, circulating pump, cooler and flow regulating valve and forms loop;Heating unit contains electric heating pipe and temperature controller;Temperature detection unit is monitored raw material, circulating medium and cold water temperature by three sensors respectively;Control unit adjusts the operating parameter of each component according to temperature signal;Heat preservation unit uses thick rock wool to wrap constant temperature jacket.The constant temperature system of the application realizes raw material accurate constant temperature by cold and hot double regulation and control, realizes high-precision constant temperature control of polyurethane raw material in glue injection process, improves cooling efficiency, reduces energy consumption, while enhancing system adaptability, guarantee product forming quality.

Description

Technical Field

[0001] This invention belongs to the field of temperature control technology for polyurethane dispensing equipment, specifically relating to a constant temperature system for a polyurethane dispensing machine with a cold water circulation system and its control method. Background Technology

[0002] Polyurethane dispensing machines are core equipment in the production of polyurethane products. During operation, they must maintain the polyurethane raw materials at a specific constant temperature to ensure the material's flowability, reactivity, and the final product's molding quality. Existing polyurethane dispensing machines often employ single heating or simple cooling systems, which have the following drawbacks: 1) Low temperature control accuracy makes it difficult to cope with temperature fluctuations caused by changes in ambient temperature and exothermic reactions of raw materials during production, resulting in unstable viscosity of raw materials and large deviations in the amount of adhesive injected. 2) Insufficient cooling efficiency. When the raw material reaction is exothermic or overheated, the temperature cannot be quickly reduced to the set range, which can easily cause problems such as premature solidification of the raw material and blockage of equipment pipelines. 3) High energy consumption: Traditional constant temperature systems lack efficient energy recycling mechanisms, and the heating and cooling processes are independent of each other, resulting in energy waste; 4) Existing constant temperature systems have poor adaptability and cannot flexibly adjust constant temperature parameters according to the characteristics of different polyurethane raw materials and product requirements, which limits their application range. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of the prior art and provide a constant temperature system for a polyurethane dispensing machine with a cold water circulation system and its control method, so as to achieve high-precision constant temperature control of polyurethane raw materials during the dispensing process, improve cooling efficiency, reduce energy consumption, enhance system adaptability, and ensure product molding quality.

[0004] To achieve the above objectives, the present invention is implemented using the following technical solution: In a first aspect, the present invention provides a constant temperature system for a polyurethane dispensing machine with a cold water circulation system, comprising a dispensing machine body, a raw material storage tank, a constant temperature jacket, a cold water circulation unit, a heating unit, a temperature detection unit, a control unit, and a heat preservation unit. The thermostatic jacket is fitted on the outside of the raw material storage tank, and a closed circulation cavity is formed between the thermostatic jacket and the raw material storage tank. The cold water circulation unit includes a cold water tank, a circulation pump, a cooler, and a flow regulating valve. The outlet of the cold water tank is connected to the inlet of the circulation pump through a pipe. The outlet of the circulation pump is connected to the inlet of the cooler through a pipe. The outlet of the cooler is connected to the inlet of the flow regulating valve through a pipe. The outlet of the flow regulating valve is connected to the inlet of the circulation chamber through a pipe. The outlet of the circulation chamber is connected to the return outlet of the cold water tank through a pipe, forming a cold water circulation loop. The heating unit includes an electric heating element and a temperature controller for adjusting the heating power of the electric heating element. The electric heating elements are evenly distributed in the circulation chamber, and the electric heating elements are electrically connected to the temperature controller. The temperature detection unit includes a first temperature sensor, a second temperature sensor, and a third temperature sensor. The first temperature sensor is located inside the raw material storage tank and is used to detect the raw material temperature. The second temperature sensor is located inside the circulation chamber and is used to detect the temperature of the circulating medium. The third temperature sensor is located inside the cold water tank and is used to detect the cold water temperature. The control unit is electrically connected to the circulating pump, cooler, flow regulating valve, temperature controller, first temperature sensor, second temperature sensor and third temperature sensor respectively. The control unit adjusts the speed of the circulating pump, the cooling power of the cooler, the opening degree of the flow regulating valve and the heating power of the electric heating tube according to the temperature signals detected by each temperature sensor.

[0005] Furthermore, the insulation unit includes an insulation layer made of rock wool insulation material and wrapped around the outside of the constant temperature jacket, with a thickness of 5~10cm.

[0006] Furthermore, the cold water tank is equipped with a liquid level sensor, which is electrically connected to the control unit. When the water level in the cold water tank is lower than a set threshold, the control unit sends an alarm signal and controls the circulation pump to stop working.

[0007] Furthermore, the cooler is a plate heat exchanger with a heat exchange area of ​​1-3 m² and an operating pressure of 0.3-0.8 MPa.

[0008] Furthermore, the electric heating element is made of stainless steel, has a power of 1-5kW, and has an anti-corrosion coating on its surface.

[0009] Furthermore, the temperature detection unit has a detection accuracy of ±0.1℃, and the temperature sensor has an operating temperature range of -20℃ to 150℃.

[0010] Furthermore, the control unit is a PLC controller, which is equipped with a touch screen display for setting constant temperature parameters, displaying real-time temperature and equipment operating status.

[0011] Furthermore, the control unit adjusts the temperature based on the temperature signals detected by each temperature sensor, including the following steps: Step S1: The control unit periodically collects the raw material temperature Tr detected by the first temperature sensor, the circulating medium temperature Tc detected by the second temperature sensor, and the cold water temperature Tw detected by the third temperature sensor. At the same time, it collects the circulating flow rate Q, the cold water tank level H, and the operating status parameters of the circulating pump, cooler, and flow regulating valve to form a system operation dataset. Step S2: The control unit compares the raw material temperature Tr with the set temperature Ts to obtain the temperature deviation ΔT=Tr−Ts, and calculates the temperature change rate per unit time to characterize the trend of system heat load change; Step S3: The control unit identifies the current operating status of the system based on the changes in temperature deviation ΔT, temperature change rate, and circulating flow rate Q, and classifies the operating status into rapid adjustment condition, fine adjustment condition, or steady-state insulation condition. Step S4: The control unit predicts the system heat load based on the temperature change rate, ambient temperature change, and circulation flow rate change trend, and generates feedforward compensation to adjust the cooling or heating capacity in advance. Step S5: When the system is in rapid adjustment mode, the control unit increases the speed of the circulating pump and increases the cooling power of the cooler or the heating power of the electric heating tube, while increasing the opening of the flow regulating valve to improve the heat exchange capacity of the circulating medium and make the raw material temperature quickly approach the set temperature. Step S6: When the system is in fine adjustment mode, the control unit performs proportional-integral-derivative adjustment on the circulating pump speed, cooler power and electric heating tube power according to the temperature deviation and feedforward compensation, so that the raw material temperature gradually approaches the set temperature and reduces temperature overshoot. Step S7: When the temperature deviation is less than the set stable threshold, the system enters the steady-state heat preservation mode. The control unit reduces the speed of the circulating pump and limits the maximum output power of the cooler and electric heating tube, only compensating for the system heat loss to maintain temperature stability. Step S8: The control unit performs linkage control based on the detection results of the circulation flow rate Q and the water level H in the cold water tank. When the circulation flow rate is lower than the set threshold, the output power of the cooler and electric heating tube is limited. When the water level is lower than the set water level, the circulation pump is controlled to stop running and an alarm signal is issued. Step S9: During the temperature stabilization phase, the control unit prioritizes low-speed, low-power continuous operation to control the circulating pump and cooler, in order to reduce energy consumption and mechanical wear caused by frequent start-ups and shutdowns of the equipment. Step S10: The control unit records the temperature regulation parameters under different ambient temperatures, circulation flow rates and heat loads, and calls up the historical optimal parameters when the same or similar operating conditions occur, so as to improve temperature control efficiency and reduce system energy consumption.

[0012] Furthermore, when the water level in the cold water tank falls below a set threshold, the control unit issues an alarm signal and controls the circulation pump to stop working, including the following steps: Step S1: The control unit periodically collects the liquid level height H detected by the liquid level sensor in the cold water tank, and at the same time collects the cooling water inlet flow rate Qin, the outlet flow rate Qout, the operating status of the circulating pump, the system target temperature Ts, and the current raw material temperature Tr to form liquid level operation data; Step S2: The control unit compares the liquid level height H with the preset liquid level threshold, and divides the liquid level of the cold water tank into ultra-low liquid level zone, low liquid level zone, normal liquid level zone, high liquid level zone and ultra-high liquid level zone according to the liquid level height. Step S3: When the liquid level is in the ultra-low liquid level zone, the control unit activates the water shortage protection mode, immediately shuts down the operation of the circulating pump and cooler, issues an alarm signal, and at the same time controls the water replenishment device to replenish water to the cold water tank at the maximum water replenishment flow rate. Step S4: When the liquid level is in the low liquid level zone, the control unit limits the cooling power of the cooler and the speed of the circulating pump, and controls the water replenishment device to continuously replenish water at the set water replenishment flow rate, so that the liquid level gradually returns to the normal liquid level zone. Step S5: When the liquid level is in the normal liquid level zone, the control unit keeps the circulating pump and cooler running at the set power according to the system temperature control requirements, and at the same time maintains the liquid level stability by finely adjusting the water replenishment flow rate; Step S6: When the liquid level is in the high liquid level zone, the control unit gradually reduces the water replenishment flow rate and appropriately increases the circulation flow rate to enhance the heat exchange capacity of the circulating medium and reduce the rate of water level rise. Step S7: When the liquid level reaches the high liquid level zone, the control unit shuts off the water supply device and discharges excess cooling water through the overflow pipe or drainage device to prevent the cold water tank from overflowing. Step S8: The control unit predicts the change in the cold water tank level based on the changing trend of the cooling water outlet flow rate Qout. When an increase in the outlet flow rate is detected, the control unit activates the water replenishment device in advance to perform feedforward water replenishment in order to reduce the fluctuation of the water level. Step S9: The control unit adjusts the cooling system load according to the cold water tank level. When the liquid level is sufficient, the cooling system is allowed to operate at high power. When the liquid level is low, the circulation pump speed and cooler power are reduced to prioritize liquid level stability. Step S10: The control unit records the changes in the cold water tank level under different operating conditions and predicts the timing of water replenishment based on historical data, so as to realize the adaptive liquid level regulation operation of the cooling system.

[0013] Secondly, the present invention provides a method for regulating the temperature control system of a polyurethane dispensing machine with a cold water circulation system as described in any of the first aspects, comprising the following steps: Step S1: Start the control unit, initialize the first temperature sensor, the second temperature sensor, the third temperature sensor, the liquid level sensor and the circulating flow detection device, and set the raw material target temperature Ts, temperature stability threshold, circulating flow threshold and cold water tank liquid level threshold on the touch screen. Step S2: The control unit periodically collects the raw material temperature Tr, circulating medium temperature Tc, cold water temperature Tw, circulating flow rate Q, and cold water tank level H, and collects the operating status parameters of the circulating pump, cooler, flow regulating valve, and electric heating tube to form a system operation dataset; Step S3: The control unit compares the raw material temperature Tr with the target temperature Ts, calculates the temperature deviation ΔT, and calculates the temperature change rate per unit time based on the continuously collected temperature data to determine the trend of system heat load change. Step S4: The control unit identifies the current operating status of the system based on the changes in temperature deviation ΔT, temperature change rate, and circulating flow rate Q, and classifies the operating status into rapid adjustment condition, fine adjustment condition, or steady-state heat preservation condition. Step S5: When the raw material temperature is higher than the target temperature, the control unit increases the speed of the circulating pump and the cooling power of the cooler, while increasing the opening of the flow regulating valve to enhance the circulating heat exchange; when the raw material temperature is lower than the target temperature, the control unit increases the heating power of the electric heating tube and adjusts the circulating flow rate to bring the raw material temperature closer to the target temperature. Step S6: When the system is in fine adjustment mode, the control unit performs proportional-integral-derivative adjustment on the circulating pump speed, cooler power and electric heating tube power according to the temperature deviation ΔT, so as to reduce temperature overshoot and improve temperature stability. Step S7: When the temperature deviation is less than the set stable threshold, the control unit puts the system into a steady-state heat preservation mode, and reduces the speed of the circulating pump and limits the maximum output power of the cooler and electric heating tube to only compensate for the heat loss of the system to maintain the stability of the raw material temperature. Step S8: The control unit performs graded control of the liquid level based on the detection result of the liquid level H in the cold water tank. When the liquid level is lower than the set liquid level threshold, an alarm signal is issued and the circulation pump is stopped. At the same time, the water replenishment device is started to replenish water to the cold water tank. Step S9: The control unit performs linkage control based on the changing trends of the circulating flow rate Q and the cold water tank level H. When the circulating flow rate suddenly increases, the water replenishment device is activated in advance to perform feedforward water replenishment, and the operating power of the cooling system is dynamically adjusted according to the liquid level status. Step S10: The control unit records the temperature regulation parameters under different ambient temperatures, circulation flow rates and heat loads, and recalls the historical optimal control parameters when the same or similar operating conditions occur.

[0014] Compared with the prior art, the beneficial effects achieved by the present invention are as follows: The constant temperature system and control method of the polyurethane dispensing machine with cold water circulation system provided by the present invention, by setting the cold water circulation unit and the heating unit to work together, and with the high-precision temperature monitoring unit and control unit, achieves precise control of the temperature of polyurethane raw materials, with a constant temperature accuracy of ±0.1℃, effectively solving the problem of low constant temperature accuracy in the prior art, and ensuring the fluidity and reaction stability of the raw materials. The cold water circulation unit uses a plate heat exchanger as a cooler, which has high heat exchange efficiency. The cold water flow rate is regulated by a flow regulating valve, which can quickly respond to temperature changes. When the raw material temperature is too high, it can quickly reduce the temperature to the set range to prevent the raw material from solidifying prematurely and improve production continuity. The control unit intelligently adjusts the circulation pump speed, cooler cooling power and electric heating tube heating power according to the detection signals of each temperature sensor, realizing efficient energy utilization. Compared with traditional constant temperature systems, energy consumption is reduced by more than 30%. The constant temperature parameters can be flexibly set via the touch screen to adapt to the constant temperature requirements of different types of polyurethane raw materials, thus expanding the application range of the equipment. The setting of the heat preservation unit reduces the heat loss of the circulating medium, further improving the constant temperature stability and reducing energy consumption. Polyurethane products produced using the constant temperature system of this invention have good density uniformity, small hardness deviation, and significantly improved product quality. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the structure of a constant temperature system for a polyurethane dispensing machine with a cold water circulation system, provided as an embodiment of the present invention.

[0016] Figure 2 This is a schematic diagram of the structure of a constant temperature system for a polyurethane dispensing machine with a cold water circulation system, provided as an embodiment of the present invention. Detailed Implementation

[0017] The present invention will be further described below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and should not be used to limit the scope of protection of the present invention.

[0018] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are used only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0019] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art will understand the specific meaning of the above terms in this invention based on the specific circumstances. Example 1

[0020] like Figure 1 As shown, this embodiment of the invention provides a constant temperature system for a polyurethane dispensing machine with a cold water circulation system, including a dispensing machine body, a raw material storage tank, a constant temperature jacket, a cold water circulation unit, a heating unit, a temperature detection unit, a control unit, and a heat preservation unit. The thermostatic jacket is fitted outside the raw material storage tank, and a closed circulation chamber is formed between the thermostatic jacket and the raw material storage tank. The cold water circulation unit includes a cold water tank, a circulating pump, a cooler, and a flow regulating valve. The outlet of the cold water tank is connected to the inlet of the circulating pump via a pipe. The outlet of the circulating pump is connected to the inlet of the cooler via a pipe. The outlet of the cooler is connected to the inlet of the flow regulating valve via a pipe. The outlet of the flow regulating valve is connected to the inlet of the circulation chamber via a pipe. The outlet of the circulation chamber is connected to the return outlet of the cold water tank via a pipe, forming a cold water circulation loop. The cooler is a plate heat exchanger with a heat exchange area of ​​2㎡ and an operating pressure of 0.5MPa. The heating unit includes an electric heating element and a temperature controller. The electric heating element is made of stainless steel with an anti-corrosion coating on its surface. It has a power of 3kW and is evenly distributed in the circulation chamber. The electric heating element is electrically connected to the temperature controller. The temperature detection unit includes a first temperature sensor, a second temperature sensor, and a third temperature sensor. The detection accuracy is ±0.1℃, and the working temperature range is -20℃ to 150℃. The first temperature sensor is located inside the raw material storage tank, the second temperature sensor is located inside the circulation chamber, and the third temperature sensor is located inside the cold water tank. The control unit is a PLC controller equipped with a touch screen, and is electrically connected to the circulating pump, cooler, flow regulating valve, temperature controller, various temperature sensors and liquid level sensors respectively. The insulation unit includes an 8cm thick rock wool insulation layer, which is wrapped around the outside of the constant temperature jacket; The cold water tank is equipped with a liquid level sensor, which is electrically connected to the control unit.

[0021] During operation, set the target constant temperature of the raw material to 50℃ via the touch screen, start the equipment, and the first temperature sensor detects an initial raw material temperature of 25℃. The control unit then activates the electric heating element, adjusting the heating power to 3kW. Simultaneously, it activates the circulating pump, adjusting its speed to 1500r / min and the flow regulating valve opening to 80%. Cold water enters the circulation chamber through the cooler (cooling function not activated yet), working in conjunction with the electric heating element to heat the circulating medium. When the second temperature sensor detects that the circulating medium temperature reaches 50℃, the control unit adjusts the heating power of the electric heating element to 1kW to maintain the circulating medium temperature. The temperature of the raw material is stable. When the first temperature sensor detects that the raw material temperature has risen to 50°C, the system enters a constant temperature state. If the raw material temperature rises to 51°C due to exothermic reaction during production, the first temperature sensor transmits a signal to the control unit. The control unit controls the cooler to start, adjusts the cooling power to 50%, and increases the opening of the flow regulating valve to 100% to accelerate the cold water circulation speed and quickly reduce the temperature of the circulating medium, thereby reducing the raw material temperature to 50°C. If the water level in the cold water tank is lower than the set threshold, the level sensor sends a signal, the control unit sends an alarm signal, and controls the circulating pump to stop working.

[0022] The polyurethane foam products produced using this constant temperature system were tested and found to have a density uniformity error of ±1.5% and a Shore hardness deviation of ±0.8HA, indicating stable product quality.

[0023] In this embodiment, the insulation unit includes an insulation layer made of rock wool insulation material and wrapped around the outside of the constant temperature jacket, with a thickness of 5~10cm.

[0024] The cold water tank is equipped with a liquid level sensor, which is electrically connected to the control unit. When the water level in the cold water tank is lower than the set threshold, the control unit sends an alarm signal and controls the circulation pump to stop working.

[0025] The cooler is a plate heat exchanger with a heat exchange area of ​​1-3 m² and a working pressure of 0.3-0.8 MPa.

[0026] The electric heating element is made of stainless steel, with a power of 1-5kW, and the surface of the electric heating element is coated with an anti-corrosion coating.

[0027] The temperature detection unit has a detection accuracy of ±0.1℃, and the temperature sensor has an operating temperature range of -20℃ to 150℃.

[0028] The control unit is a PLC controller, which is equipped with a touch screen display for setting constant temperature parameters, displaying real-time temperature and equipment operating status.

[0029] In this embodiment, the control unit adjusts the temperature based on the temperature signals detected by each temperature sensor, including the following steps: Step S1: The control unit periodically collects the raw material temperature Tr detected by the first temperature sensor, the circulating medium temperature Tc detected by the second temperature sensor, and the cold water temperature Tw detected by the third temperature sensor. At the same time, it collects the circulating flow rate Q, the cold water tank level H, and the operating status parameters of the circulating pump, cooler, and flow regulating valve to form a system operation dataset. Step S2: The control unit compares the raw material temperature Tr with the set temperature Ts to obtain the temperature deviation ΔT=Tr−Ts, and calculates the temperature change rate per unit time to characterize the trend of system heat load change; Step S3: The control unit identifies the current operating status of the system based on the changes in temperature deviation ΔT, temperature change rate, and circulating flow rate Q, and classifies the operating status into rapid adjustment condition, fine adjustment condition, or steady-state insulation condition. Step S4: The control unit predicts the system heat load based on the temperature change rate, ambient temperature change, and circulation flow rate change trend, and generates feedforward compensation to adjust the cooling or heating capacity in advance. Step S5: When the system is in rapid adjustment mode, the control unit increases the speed of the circulating pump and increases the cooling power of the cooler or the heating power of the electric heating tube, while increasing the opening of the flow regulating valve to improve the heat exchange capacity of the circulating medium and make the raw material temperature quickly approach the set temperature. Step S6: When the system is in fine adjustment mode, the control unit performs proportional-integral-derivative adjustment on the circulating pump speed, cooler power and electric heating tube power according to the temperature deviation and feedforward compensation, so that the raw material temperature gradually approaches the set temperature and reduces temperature overshoot. Step S7: When the temperature deviation is less than the set stable threshold, the system enters the steady-state heat preservation mode. The control unit reduces the speed of the circulating pump and limits the maximum output power of the cooler and electric heating tube, only compensating for the system heat loss to maintain temperature stability. Step S8: The control unit performs linkage control based on the detection results of the circulation flow rate Q and the water level H in the cold water tank. When the circulation flow rate is lower than the set threshold, the output power of the cooler and electric heating tube is limited. When the water level is lower than the set water level, the circulation pump is controlled to stop running and an alarm signal is issued. Step S9: During the temperature stabilization phase, the control unit prioritizes low-speed, low-power continuous operation to control the circulating pump and cooler, in order to reduce energy consumption and mechanical wear caused by frequent start-ups and shutdowns of the equipment. Step S10: The control unit records the temperature regulation parameters under different ambient temperatures, circulation flow rates and heat loads, and calls up the historical optimal parameters when the same or similar operating conditions occur, so as to improve temperature control efficiency and reduce system energy consumption.

[0030] In this embodiment, when the water level in the cold water tank is lower than a set threshold, the control unit issues an alarm signal and controls the circulation pump to stop working, including the following steps: Step S1: The control unit periodically collects the liquid level height H detected by the liquid level sensor in the cold water tank, and at the same time collects the cooling water inlet flow rate Qin, the outlet flow rate Qout, the operating status of the circulating pump, the system target temperature Ts, and the current raw material temperature Tr to form liquid level operation data; Step S2: The control unit compares the liquid level height H with the preset liquid level threshold, and divides the liquid level of the cold water tank into ultra-low liquid level zone, low liquid level zone, normal liquid level zone, high liquid level zone and ultra-high liquid level zone according to the liquid level height. Step S3: When the liquid level is in the ultra-low liquid level zone, the control unit activates the water shortage protection mode, immediately shuts down the operation of the circulating pump and cooler, issues an alarm signal, and at the same time controls the water replenishment device to replenish water to the cold water tank at the maximum water replenishment flow rate. Step S4: When the liquid level is in the low liquid level zone, the control unit limits the cooling power of the cooler and the speed of the circulating pump, and controls the water replenishment device to continuously replenish water at the set water replenishment flow rate, so that the liquid level gradually returns to the normal liquid level zone. Step S5: When the liquid level is in the normal liquid level zone, the control unit keeps the circulating pump and cooler running at the set power according to the system temperature control requirements, and at the same time maintains the liquid level stability by finely adjusting the water replenishment flow rate; Step S6: When the liquid level is in the high liquid level zone, the control unit gradually reduces the water replenishment flow rate and appropriately increases the circulation flow rate to enhance the heat exchange capacity of the circulating medium and reduce the rate of water level rise. Step S7: When the liquid level reaches the high liquid level zone, the control unit shuts off the water supply device and discharges excess cooling water through the overflow pipe or drainage device to prevent the cold water tank from overflowing. Step S8: The control unit predicts the change in the cold water tank level based on the changing trend of the cooling water outlet flow rate Qout. When an increase in the outlet flow rate is detected, the control unit activates the water replenishment device in advance to perform feedforward water replenishment in order to reduce the fluctuation of the water level. Step S9: The control unit adjusts the cooling system load according to the cold water tank level. When the liquid level is sufficient, the cooling system is allowed to operate at high power. When the liquid level is low, the circulation pump speed and cooler power are reduced to prioritize liquid level stability. Step S10: The control unit records the changes in the cold water tank level under different operating conditions and predicts the timing of water replenishment based on historical data, so as to realize the adaptive liquid level regulation operation of the cooling system.

[0031] Secondly, the present invention provides a method for regulating the temperature control system of a polyurethane dispensing machine with a cold water circulation system as described above, comprising the following steps: Step S1: Start the control unit, initialize the first temperature sensor, the second temperature sensor, the third temperature sensor, the liquid level sensor and the circulating flow detection device, and set the raw material target temperature Ts, temperature stability threshold, circulating flow threshold and cold water tank liquid level threshold on the touch screen. Step S2: The control unit periodically collects the raw material temperature Tr, circulating medium temperature Tc, cold water temperature Tw, circulating flow rate Q, and cold water tank level H, and collects the operating status parameters of the circulating pump, cooler, flow regulating valve, and electric heating tube to form a system operation dataset; Step S3: The control unit compares the raw material temperature Tr with the target temperature Ts, calculates the temperature deviation ΔT, and calculates the temperature change rate per unit time based on the continuously collected temperature data to determine the trend of system heat load change. Step S4: The control unit identifies the current operating status of the system based on the changes in temperature deviation ΔT, temperature change rate, and circulating flow rate Q, and classifies the operating status into rapid adjustment condition, fine adjustment condition, or steady-state heat preservation condition. Step S5: When the raw material temperature is higher than the target temperature, the control unit increases the speed of the circulating pump and the cooling power of the cooler, while increasing the opening of the flow regulating valve to enhance the circulating heat exchange; when the raw material temperature is lower than the target temperature, the control unit increases the heating power of the electric heating tube and adjusts the circulating flow rate to bring the raw material temperature closer to the target temperature. Step S6: When the system is in fine adjustment mode, the control unit performs proportional-integral-derivative adjustment on the circulating pump speed, cooler power and electric heating tube power according to the temperature deviation ΔT, so as to reduce temperature overshoot and improve temperature stability. Step S7: When the temperature deviation is less than the set stable threshold, the control unit puts the system into a steady-state heat preservation mode, and reduces the speed of the circulating pump and limits the maximum output power of the cooler and electric heating tube to only compensate for the heat loss of the system to maintain the stability of the raw material temperature. Step S8: The control unit performs graded control of the liquid level based on the detection result of the liquid level H in the cold water tank. When the liquid level is lower than the set liquid level threshold, an alarm signal is issued and the circulation pump is stopped. At the same time, the water replenishment device is started to replenish water to the cold water tank. Step S9: The control unit performs linkage control based on the changing trends of the circulating flow rate Q and the cold water tank level H. When the circulating flow rate suddenly increases, the water replenishment device is activated in advance to perform feedforward water replenishment, and the operating power of the cooling system is dynamically adjusted according to the liquid level status. Step S10: The control unit records the temperature regulation parameters under different ambient temperatures, circulation flow rates and heat loads, and recalls the historical optimal control parameters when the same or similar operating conditions occur. Example 2

[0032] The difference between this embodiment and Embodiment 1 is that the electric heating tube has a power of 5kW, the plate heat exchanger has a heat exchange area of ​​3㎡, the insulation layer thickness is 10cm, and the target constant temperature of the raw material is set to 60℃. During use, the control unit intelligently adjusts the operating parameters of each component based on the temperature monitoring signal, ultimately maintaining the constant temperature accuracy of the raw material at ±0.1℃. The produced polyurethane elastomer products exhibit a density uniformity error of ±1.2% and a Shore hardness deviation of ±0.6HA. Example 3

[0033] The difference between this embodiment and Embodiment 1 is that the electric heating tube power is 1kW, the plate heat exchanger heat exchange area is 1㎡, the insulation layer thickness is 5cm, and the target constant temperature of the raw materials is set to 40℃. During use, the system maintains a stable constant temperature, and the produced polyurethane sealing products exhibit a density uniformity error of ±1.8% and a Shore hardness deviation of ±0.9HA.

[0034] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A constant temperature system for a polyurethane dispensing machine with a cold water circulation system, characterized in that, It includes the dispensing machine body, raw material storage tank, constant temperature jacket, cold water circulation unit, heating unit, temperature detection unit, control unit and heat preservation unit; The thermostatic jacket is fitted on the outside of the raw material storage tank, and a closed circulation cavity is formed between the thermostatic jacket and the raw material storage tank. The cold water circulation unit includes a cold water tank, a circulation pump, a cooler, and a flow regulating valve. The outlet of the cold water tank is connected to the inlet of the circulation pump through a pipe. The outlet of the circulation pump is connected to the inlet of the cooler through a pipe. The outlet of the cooler is connected to the inlet of the flow regulating valve through a pipe. The outlet of the flow regulating valve is connected to the inlet of the circulation chamber through a pipe. The outlet of the circulation chamber is connected to the return outlet of the cold water tank through a pipe, forming a cold water circulation loop. The heating unit includes an electric heating element and a temperature controller for adjusting the heating power of the electric heating element. The electric heating elements are evenly distributed in the circulation chamber, and the electric heating elements are electrically connected to the temperature controller. The temperature detection unit includes a first temperature sensor, a second temperature sensor, and a third temperature sensor. The first temperature sensor is located inside the raw material storage tank and is used to detect the raw material temperature. The second temperature sensor is located inside the circulation chamber and is used to detect the temperature of the circulating medium. The third temperature sensor is located inside the cold water tank and is used to detect the cold water temperature. The control unit is electrically connected to the circulating pump, cooler, flow regulating valve, temperature controller, first temperature sensor, second temperature sensor and third temperature sensor respectively. The control unit adjusts the speed of the circulating pump, the cooling power of the cooler, the opening degree of the flow regulating valve and the heating power of the electric heating tube according to the temperature signals detected by each temperature sensor.

2. The constant temperature system for a polyurethane dispensing machine with a cold water circulation system according to claim 1, characterized in that, The insulation unit includes an insulation layer, which is made of rock wool insulation material and wrapped around the outside of the constant temperature jacket. The thickness of the insulation layer is 5~10cm.

3. The constant temperature system of the polyurethane dispensing machine with a cold water circulation system according to claim 2, characterized in that, The cold water tank is equipped with a liquid level sensor, which is electrically connected to the control unit. When the water level in the cold water tank is lower than a set threshold, the control unit sends an alarm signal and controls the circulation pump to stop working.

4. The constant temperature system for a polyurethane dispensing machine with a cold water circulation system according to claim 1, characterized in that, The cooler is a plate heat exchanger with a heat exchange area of ​​1-3 m² and a working pressure of 0.3-0.8 MPa.

5. The constant temperature system for a polyurethane dispensing machine with a cold water circulation system according to claim 4, characterized in that, The electric heating element is made of stainless steel, has a power of 1-5kW, and has an anti-corrosion coating on its surface.

6. The constant temperature system for a polyurethane dispensing machine with a cold water circulation system according to claim 5, characterized in that, The temperature detection unit has a detection accuracy of ±0.1℃, and the temperature sensor has an operating temperature range of -20℃ to 150℃.

7. The constant temperature system for a polyurethane dispensing machine with a cold water circulation system according to claim 6, characterized in that, The control unit is a PLC controller, which is equipped with a touch screen display for setting constant temperature parameters, displaying real-time temperature and equipment operating status.

8. The constant temperature system for a polyurethane dispensing machine with a cold water circulation system according to any one of claims 2 to 7, characterized in that, The control unit adjusts based on the temperature signals detected by each temperature sensor, including the following steps: Step S1: The control unit periodically collects the raw material temperature Tr detected by the first temperature sensor, the circulating medium temperature Tc detected by the second temperature sensor, and the cold water temperature Tw detected by the third temperature sensor. At the same time, it collects the circulating flow rate Q, the cold water tank level H, and the operating status parameters of the circulating pump, cooler, and flow regulating valve to form a system operation dataset. Step S2: The control unit compares the raw material temperature Tr with the set temperature Ts to obtain the temperature deviation ΔT=Tr−Ts, and calculates the temperature change rate per unit time to characterize the trend of system heat load change; Step S3: The control unit identifies the current operating status of the system based on the changes in temperature deviation ΔT, temperature change rate, and circulating flow rate Q, and classifies the operating status into rapid adjustment condition, fine adjustment condition, or steady-state insulation condition. Step S4: The control unit predicts the system heat load based on the temperature change rate, ambient temperature change, and circulation flow rate change trend, and generates feedforward compensation to adjust the cooling or heating capacity in advance. Step S5: When the system is in rapid adjustment mode, the control unit increases the speed of the circulating pump and increases the cooling power of the cooler or the heating power of the electric heating tube, while increasing the opening of the flow regulating valve to improve the heat exchange capacity of the circulating medium and make the raw material temperature quickly approach the set temperature. Step S6: When the system is in fine adjustment mode, the control unit performs proportional-integral-derivative adjustment on the circulating pump speed, cooler power and electric heating tube power according to the temperature deviation and feedforward compensation, so that the raw material temperature gradually approaches the set temperature and reduces temperature overshoot. Step S7: When the temperature deviation is less than the set stable threshold, the system enters the steady-state heat preservation mode. The control unit reduces the speed of the circulating pump and limits the maximum output power of the cooler and electric heating tube, only compensating for the system heat loss to maintain temperature stability. Step S8: The control unit performs linkage control based on the detection results of the circulation flow rate Q and the water level H in the cold water tank. When the circulation flow rate is lower than the set threshold, the output power of the cooler and electric heating tube is limited. When the water level is lower than the set water level, the circulation pump is controlled to stop running and an alarm signal is issued. Step S9: During the temperature stabilization phase, the control unit prioritizes low-speed, low-power continuous operation to control the circulating pump and cooler, in order to reduce energy consumption and mechanical wear caused by frequent start-ups and shutdowns of the equipment. Step S10: The control unit records the temperature regulation parameters under different ambient temperatures, circulation flow rates and heat loads, and calls up the historical optimal parameters when the same or similar operating conditions occur, so as to improve temperature control efficiency and reduce system energy consumption.

9. The constant temperature system for a polyurethane dispensing machine with a cold water circulation system according to claim 8, characterized in that, When the water level in the cold water tank falls below a set threshold, the control unit issues an alarm signal and controls the circulation pump to stop working, including the following steps: Step S1: The control unit periodically collects the liquid level height H detected by the liquid level sensor in the cold water tank, and at the same time collects the cooling water inlet flow rate Qin, the outlet flow rate Qout, the operating status of the circulating pump, the system target temperature Ts, and the current raw material temperature Tr to form liquid level operation data; Step S2: The control unit compares the liquid level height H with the preset liquid level threshold, and divides the liquid level of the cold water tank into ultra-low liquid level zone, low liquid level zone, normal liquid level zone, high liquid level zone and ultra-high liquid level zone according to the liquid level height. Step S3: When the liquid level is in the ultra-low liquid level zone, the control unit activates the water shortage protection mode, immediately shuts down the operation of the circulating pump and cooler, issues an alarm signal, and at the same time controls the water replenishment device to replenish water to the cold water tank at the maximum water replenishment flow rate. Step S4: When the liquid level is in the low liquid level zone, the control unit limits the cooling power of the cooler and the speed of the circulating pump, and controls the water replenishment device to continuously replenish water at the set water replenishment flow rate, so that the liquid level gradually returns to the normal liquid level zone. Step S5: When the liquid level is in the normal liquid level zone, the control unit keeps the circulating pump and cooler running at the set power according to the system temperature control requirements, and at the same time maintains the liquid level stability by finely adjusting the water replenishment flow rate; Step S6: When the liquid level is in the high liquid level zone, the control unit gradually reduces the water replenishment flow rate and appropriately increases the circulation flow rate to enhance the heat exchange capacity of the circulating medium and reduce the rate of water level rise. Step S7: When the liquid level reaches the high liquid level zone, the control unit shuts off the water supply device and discharges excess cooling water through the overflow pipe or drainage device to prevent the cold water tank from overflowing. Step S8: The control unit predicts the change in the cold water tank level based on the changing trend of the cooling water outlet flow rate Qout. When an increase in the outlet flow rate is detected, the control unit activates the water replenishment device in advance to perform feedforward water replenishment in order to reduce the fluctuation of the water level. Step S9: The control unit adjusts the cooling system load according to the cold water tank level. When the liquid level is sufficient, the cooling system is allowed to operate at high power. When the liquid level is low, the circulation pump speed and cooler power are reduced to prioritize liquid level stability. Step S10: The control unit records the changes in the cold water tank level under different operating conditions and predicts the timing of water replenishment based on historical data, so as to realize the adaptive liquid level regulation operation of the cooling system.

10. A method for controlling the temperature control system of a polyurethane dispensing machine with a cold water circulation system as described in any one of claims 1 to 9, characterized in that, Includes the following steps: Step S1: Start the control unit, initialize the first temperature sensor, the second temperature sensor, the third temperature sensor, the liquid level sensor and the circulating flow detection device, and set the raw material target temperature Ts, temperature stability threshold, circulating flow threshold and cold water tank liquid level threshold on the touch screen. Step S2: The control unit periodically collects the raw material temperature Tr, circulating medium temperature Tc, cold water temperature Tw, circulating flow rate Q, and cold water tank level H, and collects the operating status parameters of the circulating pump, cooler, flow regulating valve, and electric heating tube to form a system operation dataset; Step S3: The control unit compares the raw material temperature Tr with the target temperature Ts, calculates the temperature deviation ΔT, and calculates the temperature change rate per unit time based on the continuously collected temperature data to determine the trend of system heat load change. Step S4: The control unit identifies the current operating status of the system based on the changes in temperature deviation ΔT, temperature change rate, and circulating flow rate Q, and classifies the operating status into rapid adjustment condition, fine adjustment condition, or steady-state heat preservation condition. Step S5: When the raw material temperature is higher than the target temperature, the control unit increases the speed of the circulating pump and the cooling power of the cooler, while increasing the opening of the flow regulating valve to enhance the circulating heat exchange; when the raw material temperature is lower than the target temperature, the control unit increases the heating power of the electric heating tube and adjusts the circulating flow rate to bring the raw material temperature closer to the target temperature. Step S6: When the system is in fine adjustment mode, the control unit performs proportional-integral-derivative adjustment on the circulating pump speed, cooler power and electric heating tube power according to the temperature deviation ΔT, so as to reduce temperature overshoot and improve temperature stability. Step S7: When the temperature deviation is less than the set stable threshold, the control unit puts the system into a steady-state heat preservation mode, and reduces the speed of the circulating pump and limits the maximum output power of the cooler and electric heating tube to only compensate for the heat loss of the system to maintain the stability of the raw material temperature. Step S8: The control unit performs graded control of the liquid level based on the detection result of the liquid level H in the cold water tank. When the liquid level is lower than the set liquid level threshold, an alarm signal is issued and the circulation pump is stopped. At the same time, the water replenishment device is started to replenish water to the cold water tank. Step S9: The control unit performs linkage control based on the changing trends of the circulating flow rate Q and the cold water tank level H. When the circulating flow rate suddenly increases, the water replenishment device is activated in advance to perform feedforward water replenishment, and the operating power of the cooling system is dynamically adjusted according to the liquid level status. Step S10: The control unit records the temperature regulation parameters under different ambient temperatures, circulation flow rates and heat loads, and recalls the historical optimal control parameters when the same or similar operating conditions occur.

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