Pulse cooling and heating intelligent mold temperature controller and control method

Abstract

The invention relates to the technical field of mold temperature control, and particularly discloses a pulse cooling and heating intelligent mold temperature controller and a control method. Comprising a plurality of mold cavity surface temperature sensors, a waterway temperature sensor, a flow sensor, a liquid electromagnetic valve group, a mold heater and a control unit electrically connected with the sensors, the electromagnetic valve group and the heater, according to the method, the mold surface temperature fluctuation can be obviously reduced, the mold surface temperature peak-peak fluctuation after pulse cooling control is obviously reduced, and the dimensional stability and the surface quality of an injection molding part can be improved; through zoning temperature control, the temperature difference of all parts of the mold is reduced, and warping and internal stress concentration can be reduced; due to the fact that the low-temperature refrigerant is adopted, the heat exchange efficiency is obviously improved, the cooling time is shortened, and the production efficiency is improved; and through the real-time monitoring and protection strategy of the flow / temperature difference, the risks of mold thermal shock and equipment failure caused by abnormal cooling are reduced.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of mold temperature control, and particularly relates to an intelligent mold temperature controller for pulse cooling and heating and a control method. BACKGROUND

[0002] In the aspect of plastic mold temperature control, currently, a mold temperature machine or a cold water machine is generally used to continuously cool through the cooling water circuit of the mold, and the cooling medium can be cooling oil or cooling water. High-temperature molds generally use oil-type mold temperature machines, and medium and low-temperature molds use water-type mold temperature machines or cold water machines. The temperature of the mold is determined by the cooling medium temperature of the mold temperature machine or the cold water machine. Such a control method can have several problems. First, the mold temperature deviation is relatively large. When the molten plastic enters the mold cavity, the heat that can be taken away by continuous cooling is a constant, and the heat of the molten plastic cannot be taken away in time, resulting in a large mold temperature rise. Second, the cooling efficiency is low. Different plastics have different temperature requirements for mold temperature when they are molded and solidified. When continuous cooling is used, the temperature of the mold temperature machine must be adjusted to the temperature required for the material to be molded and solidified. Especially in the case where the mold temperature requirement is relatively high, the heat removal speed is slow, resulting in a long cooling time and affecting the production efficiency. Third, the precision of the plastic product is affected, especially for precision plastic products. The mold temperature, as an important condition for plastic molding, can greatly affect the precision of the plastic product. Fourth, the coolant continuously circulates in the mold water circuit, and when the product has been solidified and molded in the mold and does not need to be cooled, the cooling is ineffective, resulting in energy loss.

[0003] To solve the above problems, the present application provides an intelligent mold temperature controller for pulse cooling and heating and a control method. SUMMARY

[0004] The present application aims to provide an intelligent mold temperature controller for pulse cooling and heating and a control method to solve the problems raised in the background.

[0005] To achieve the above-mentioned purpose, the present application provides the following technical solutions:

[0006] The intelligent mold temperature controller for pulse cooling and heating comprises:

[0007] a plurality of mold cavity surface temperature sensors, water circuit temperature sensors, flow sensors, liquid solenoid valve groups, mold heaters, and a control unit electrically connected to the above-mentioned sensors, the solenoid valve groups, and the heaters;

[0008] The control unit is used to output pulse control signals according to a pulse control strategy based on the mold cavity surface temperature, the return water temperature, and the flow to drive the solenoid valve groups and the heaters, so as to realize the closed-loop temperature control of the pulse cooling and heating of the mold.

[0009] Preferably, the control unit comprises a PLC or embedded host module, an HMI for human-machine interaction, a data recording module, and an interface for communicating with the injection molding machine or molding machine to obtain process stage signals;

[0010] The electromagnetic valve group is a multi-path partition electromagnetic valve, each path corresponding to one or more partitions of the mold, and the control unit generates independent or coordinated pulse control signals for each partition according to the temperature of each partition and the importance of each partition;

[0011] The output of the flow sensor is used to determine the health status of the loop in real time, and when the flow or temperature difference is detected to be lower than the preset threshold, the sensor is abnormal, or the valve response is abnormal, the control unit performs a protection action and sends an alarm.

[0012] Preferably, the control unit can use a control method matched with the type of temperature sensor used, such as a mold surface temperature sensor or a waterway temperature sensor, and the mode of injection molding, including rapid cooling, short cycle or long cycle.

[0013] Another aspect of the present application is to provide a control method for an intelligent mold temperature controller for pulse cooling and heating, applied to the above-mentioned controller, the method comprising the following steps:

[0014] S1, rapid cooling mode: using a mold surface temperature sensor, when the measured temperature is greater than the temperature set value, the liquid electromagnetic valve is opened, and when the measured temperature is lower than the temperature set value, the liquid electromagnetic valve is closed;

[0015] S2, short cycle cooling mode: using a mold surface temperature sensor, the controller receives a synchronization signal from the machine and gives a pulse signal (adjustable), and measures whether the temperature exceeds the upper limit, and when it exceeds, the valve is opened, and when it is lower, the valve is closed;

[0016] S3, long cycle cooling mode: using a mold surface temperature sensor, the controller outputs a pulse signal according to the set temperature and adjusts the interval and size (PID control);

[0017] S4, sensor installed in the cooling waterway mode: the controller opens the liquid electromagnetic valve once every period, and when the water temperature is detected to be greater than the set temperature value, the valve is opened, but when the temperature is lower than the temperature set value, the valve is closed;

[0018] S5, the controller uses a mold surface or waterway temperature sensor and a flow sensor to collect temperature and flow data in real time, and monitors according to the set temperature upper and lower limits and the flow lower limit value, and when the real-time temperature and flow are detected to be out of limits, the controller sends an alarm signal;

[0019] S6, continuously collecting the actual temperature of the mold surface or water return through the mold surface temperature sensor or water temperature sensor, comparing with the set temperature, forming a temperature curve with the target temperature (set temperature) as the axis, and the collection period can be adjusted.

[0020] Preferably, the rapid cooling mode in step S1, that is, using a mold surface temperature sensor, when the measured temperature is greater than the temperature set value, the liquid electromagnetic valve is opened, and when the measured temperature is lower than the temperature set value, the liquid electromagnetic valve is closed.

[0021] Preferably, the short cycle cooling mode in step S2, that is, using a mold surface temperature sensor, the controller gives a pulse signal (adjustable) when receiving the synchronization signal of the machine, and measures whether the temperature exceeds the upper limit, and opens the valve when it exceeds, and closes the valve when it is lower.

[0022] Preferably, the long cycle cooling mode in step S3, that is, using a mold surface temperature sensor, the controller outputs a pulse signal according to the set temperature and adjusts the interval and size (PID control).

[0023] Preferably, the sensor installation in the cooling water circuit mode in step S4, that is, the controller opens the liquid electromagnetic valve once every period, and when the detected water temperature is greater than the set temperature value, the valve is opened, but when the temperature is lower than the temperature set value, the valve is closed.

[0024] Preferably, in step S5, the measured temperature and flow are compared with the preset threshold value to determine whether the circuit is in a working condition that meets the heat transfer requirement or in an abnormal working condition, and a circuit working condition state identifier is obtained; the circuit working condition state identifier includes normal, pre-warning and failure.

[0025] Preferably, in step S6, by setting the mold target temperature required for molding, the controller obtains the real-time temperature curve with the required coordinates and length from the continuously collected measured temperature.

[0026] Compared with the prior art, the beneficial effects of the present application are:

[0027] (1) The present application is different from the continuous cooling mode. The heat exchange efficiency is greatly improved by using a lower temperature coolant. Through rapid heat exchange, when the molten plastic enters the mold cavity, the mold temperature can be prevented from rising rapidly due to the input of a large amount of heat, and the mold temperature can be kept constant in a relatively narrow range, thereby improving the mold temperature control precision. Compared with the traditional mold temperature machine, the coolant used has a temperature much lower than the required temperature of the mold during the solidification of the plastic, and the cooling efficiency is greatly improved, thereby shortening the cooling time and improving the production efficiency. Multiple temperature controls are provided at different parts of the mold, so that the overall temperature of the mold is more uniform, and the quality of the plastic product can be improved. Because of the intermittent cooling mode, cooling is provided according to actual requirements, which can greatly save cooling medium and reduce energy consumption compared with the continuous cooling mode. Real-time flow detection can timely reflect the mold cooling state, and the cooling circuit can be checked and troubleshot more quickly, thereby facilitating the inspection and maintenance of the equipment.

[0028] (2) The present application can significantly reduce the temperature fluctuation of the mold surface, and the peak-to-peak fluctuation of the mold surface temperature after pulse control is significantly reduced, which is beneficial to improve the dimensional stability and surface quality of the injection molded part. The maximum temperature difference between the partitions is reduced, which helps to reduce warping and internal stress concentration. Because of the use of a lower temperature coolant, the heat exchange efficiency is significantly improved, the cooling time is shortened, and the production efficiency is improved. During the trial production stage, the output per unit time is significantly increased, and the number of defective products is reduced. Through real-time monitoring of the flow / temperature difference and protection strategy, the risk of mold thermal shock and equipment failure caused by abnormal cooling is reduced. The pulse cooling mode embodies the on-demand cooling, reduces the energy loss caused by continuous circulation of the coolant during normal mold cooling, and has good energy-saving effect. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 It is one of the composition block diagrams of the pulse cooling and heating intelligent mold temperature controller of the present application;

[0030] Figure 2 It is the second composition block diagram of the pulse cooling and heating intelligent mold temperature controller of the present application;

[0031] Figure 3 It is the third composition block diagram of the pulse cooling and heating intelligent mold temperature controller of the present application;

[0032] Figure 4 It is a low-temperature mold forming control chart of an embodiment of the present application;

[0033] Figure 5 It is a high-temperature mold forming control chart of an embodiment of the present application;

[0034] Figure 6 It is an ultrahigh-temperature mold forming control chart of an embodiment of the present application. DETAILED DESCRIPTION

[0035] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative effort belong to the scope of protection of the present application.

[0036] Embodiment one:

[0037] Please refer to Figures 1 to 3 The pulse cooling and heating intelligent mold temperature controller comprises:

[0038] a plurality of mold cavity surface temperature sensors, waterway temperature sensors, flow sensors, a liquid electromagnetic valve group, a mold heater, and a control unit electrically connected with the above-mentioned sensors, the electromagnetic valve group, and the heater;

[0039] The control unit is configured to output pulse control signals according to a pulse control strategy based on the mold cavity surface temperature, the return water temperature, and the flow, so as to drive the electromagnetic valve group and the heater, so as to realize closed-loop temperature control of pulse cooling and heating of the mold.

[0040] Specifically, the control unit comprises a PLC or an embedded main control module, an HMI for human-computer interaction, a data recording module, and an interface for communicating with an injection molding machine or a molding machine to obtain process stage signals.

[0041] The electromagnetic valve group is a multi-way partition electromagnetic valve, each way corresponding to one or more partitions of the mold, and the control unit generates pulse control signals for each way independently or cooperatively according to the temperature of each partition and the importance of each partition.

[0042] The output of the flow sensor is used to judge the health status of the loop in real time, and when the flow or temperature difference is lower than the preset threshold, the sensor is abnormal, or the valve response is abnormal, the control unit performs a protection action and issues an alarm.

[0043] Specifically, the pulse cooling and heating intelligent mold temperature controller is characterized in that the control unit can adopt a control mode matched with the type of temperature sensor used, such as a mold surface temperature sensor or a waterway temperature sensor, and the mode of injection molding, such as rapid cooling, short cycle, or long cycle.

[0044] The control method of the pulse cooling and heating intelligent mold temperature controller is characterized by the following:

[0045] S1, fast cooling mode: using mold surface temperature sensor, when the measured temperature is greater than the temperature set value, the liquid solenoid valve is opened, when the measured temperature is lower than the temperature set value, the liquid solenoid valve is closed.

[0046] S2, short cycle cooling mode: using mold surface temperature sensor, the controller receives a pulse signal (adjustable) when the machine synchronization signal is received, and measures whether the temperature exceeds the upper limit, and the valve is opened when it exceeds, and the valve is closed when it is lower.

[0047] S3, long cycle cooling mode: using mold surface temperature sensor, the controller outputs pulse signal according to the set temperature and adjusts the interval and size (PID control)

[0048] S4, sensor installed in cooling water mode: the controller opens the liquid solenoid valve every period, and the valve is opened when the detected water temperature is greater than the set temperature value, but the valve is closed when the temperature is lower than the temperature set value.

[0049] S5, the controller uses mold or water temperature sensor and flow sensor to collect temperature and flow data in real time, and monitors according to the set temperature upper and lower limits and flow lower limit value, and sends an alarm signal when the real-time temperature and flow are detected to be out of limit

[0050] S6, the actual temperature of the mold surface or water return is continuously collected by the mold surface temperature sensor or water temperature sensor, and compared with the set temperature to form a temperature curve with the target temperature (set temperature) as the axis, and the collection period can be adjusted.

[0051] Before the equipment selection, the project evaluation will be carried out, such as the heat brought in each cycle, cycle time, mold heat dissipation and so on, and the appropriate machine model and configuration are evaluated.

[0052] As can be seen from the above, the difference from the continuous cooling mode is that the use of lower temperature refrigerant greatly improves the heat exchange efficiency. Through rapid heat exchange, when the molten plastic enters the mold cavity, it can prevent the rapid temperature rise of the mold temperature caused by a large amount of heat input, and keep the mold temperature constant in a relatively narrow range, improving the mold temperature control precision.

[0053] Compared with the traditional mold temperature machine, the use of refrigerant with temperature much lower than the temperature required by the mold during plastic molding and curing greatly improves the cooling efficiency, shortens the cooling time and improves the production efficiency.

[0054] Multiple temperature control can be set up at different parts of the mold to make the overall temperature of the mold more uniform and improve the quality of plastic products.

[0055] Because of the intermittent cooling mode, cooling is provided according to actual requirements, which can greatly save cooling medium and reduce energy consumption compared with continuous cooling mode.

[0056] Real-time flow detection can reflect the mold cooling state in time, faster cooling circuit inspection and troubleshooting, facilitate the inspection and maintenance of the equipment, and reduce the related investment.

[0057] Through different control methods, different mold temperature control requirements can be met, and the use range is wide.

[0058] Example two:

[0059] As shown in Figures 4-6 Product and mold basic information:

[0060] Product: shell; mass 55.96g; size 110x117x67mm; wall thickness range 2.5mm / 1.4mm(max / min); material PP+GF10; hole number 2; injection molding machine: vertical 200t; mold structure: one upper and two lower.

[0061] On-site observation:

[0062] Baseline (continuous cooling of mold temperature machine) cycle: 30s; cooling time 12s.

[0063] This embodiment (pulse cooling) cycle: 26s; cooling time 8s.

[0064] Implementation method:

[0065] 1. According to the mold structure, the upper mold and the two lower molds are divided into three temperature control zones, and the three temperature control zones are all installed with mold surface temperature sensors for collecting the real-time temperature of the mold cavity, and the collection frequency is 20ms;

[0066] 2. Considering that the material is PP, a large amount of cooling is needed during solidification, so a fast cooling method is adopted, that is, using mold surface temperature sensor, when the measured temperature is greater than the temperature setting value, the liquid electromagnetic valve is opened, when the measured temperature is lower than the temperature setting value, the liquid electromagnetic valve is closed;

[0067] 3. According to the temperature requirement of PP material forming, the mold cavity temperature is set to 40℃;

[0068] 4. Replace the original mold temperature machine with a cold water machine, and set the refrigerant temperature to 18℃, (the temperature of the mold temperature machine refrigerant is 40℃);

[0069] 5. Use 3 groups of liquid electromagnetic valves (including flow sensors) to correspond to 3 mold surface temperature sensors, and carry out temperature closed-loop control of 3 mold temperature controllers.

[0070] Implementation results:

[0071] Cycle time: from 30s to 26s, absolute reduction of 4s, about 13.33% reduction.

[0072] Cooling time: from 12s to 8s, absolute reduction of 4s, about 33.33% reduction (exemplary measurement).

[0073] Yield improvement (theoretical calculation):

[0074] Baseline yield: 3600 / 30 = 120 pieces / hour;

[0075] Pulse scheme yield: 3600 / 26 ≈ 138.46 pieces / hour;

[0076] Absolute increase ≈ 18.46 pieces / hour, relative increase about 15.38%.

[0077] Calculated on an 8-hour shift: from 960 pieces / shift to ≈ 1107.7 pieces / shift, an increase of about 147.7 pieces per day (8h). (The above yield calculation is based on the theoretical value of single machine continuous production, and the actual yield is affected by mold changing, downtime, etc.)

[0078] Electricity comparison:

[0079] This scheme: pulse cooling + cold water unit combination:

[0080] Production time 23 hours, power consumption 62kwh, average hourly power consumption: 62 / 23 = 2.7kw

[0081] Traditional scheme: mold temperature controller + hot runner controller:

[0082] Production time 12 hours, power consumption 58.7kwh, average hourly power consumption: 58.7 / 12 = 4.9kw,

[0083] Electricity comparison:

[0084] Pulse cooling controller + cold water unit, average hourly power consumption is 2.7kw; mold temperature controller average hourly power consumption is 4.9kw, can save electricity 2.2kw per hour, according to 22 hours of work per day, 300 days a year, can save electricity 14520 degrees, according to industrial flat electricity price 0.62 yuan / degree, can save electricity fee 9002.4 yuan.

[0085] As can be seen from the above, the design can significantly reduce the fluctuation of mold surface temperature: after pulse control, the peak-peak fluctuation of mold surface temperature is significantly reduced, which is conducive to improving the dimensional stability and surface quality of injection molded parts.

[0086] Significant improvement in temperature non-uniformity in subareas: reduction of maximum temperature difference between subareas, which helps to reduce warping and internal stress concentration.

[0087] Part defect / reject rate reduction: During the field trial, the reject rate was significantly reduced, and the rate of returned and scrapped parts was also reduced.

[0088] Energy consumption and resource utilization improvement: Due to the on-demand cooling and duty cycle optimization, the cooling medium pump and the cold source operate more optimally, and the energy consumption is estimated to be reduced.

[0089] Mold and equipment reliability improvement: Through real-time monitoring of flow / temperature difference and protection strategy, the risk of mold thermal shock and equipment failure caused by abnormal cooling is reduced.

[0090] As can be seen from the above, directly reducing the field baseline cycle from 30s to 26s (cooling time from 12s to 8s) achieves synchronous shortening of the cycle and cooling time, significantly improves productivity and reduces the waiting time for cooling of each part.

[0091] Productivity improvement and energy efficiency improvement are parallel, and the safe and stable operation of the equipment and mold is guaranteed through the flow / temperature difference protection logic.

[0092] Although embodiments of the present application have been shown and described, it will be understood by those having ordinary skill in the art that various changes, modifications, substitutions and alterations can be made therein without departing from the principles and spirit of the present application, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A pulse cooling and heating intelligent mold temperature controller, characterized in that, include: A plurality of mold cavity surface temperature sensors, water circuit temperature sensors, flow sensors, liquid solenoid valve groups, mold heaters, and control units electrically connected to the aforementioned sensors, the solenoid valve groups, and the heaters; The control unit is used to output pulse control signals according to the pulse control strategy based on the surface temperature of the mold cavity, the return water temperature and the flow rate, so as to drive the solenoid valve group and the heater, thereby realizing closed-loop temperature control of mold cooling and heating.

2. The intelligent mold temperature controller for pulse cooling and heating according to claim 1, characterized in that, The control unit includes a PLC or embedded main control module, an HMI for human-machine interaction, a data recording module, and an interface for communicating with the injection molding machine or molding machine to obtain process stage signals. The solenoid valve group is a multi-channel partitioned solenoid valve, with each channel corresponding to one or more partitions of the mold, and the control unit generates independent or coordinated pulse control signals for each partition based on the temperature and importance of each partition. The output of the flow sensor is used to determine the health status of the circuit in real time. When the flow rate or temperature difference is detected to be lower than a preset threshold, or when the sensor or valve response is abnormal, the control unit performs a protection action and issues an alarm.

3. The intelligent mold temperature controller for pulse cooling and heating according to claim 1, characterized in that, The control unit can adopt a matching control method according to the type of temperature sensor used, such as a mold surface temperature sensor or a water circuit temperature sensor, and the injection molding method, including rapid cooling, short cycle or long cycle.

4. A control method for a pulse cooling and heating intelligent mold temperature controller, characterized in that, Applied to the controller as described in any one of claims 1-3, the control method includes the following steps: S1. Rapid cooling method: A mold surface temperature sensor is used. When the measured temperature is greater than the temperature set value, the liquid solenoid valve opens; when the measured temperature is lower than the temperature set value, the liquid solenoid valve closes. S2, Short-cycle cooling mode: Using a mold surface temperature sensor, the controller sends a pulse signal when it receives the machine's synchronization signal, and at the same time measures whether the temperature exceeds the upper limit. If it exceeds the upper limit, the valve opens; if it is below the upper limit, the valve closes. S3, Long-cycle Cooling Mode: Employs a mold surface temperature sensor, and the controller outputs pulse signals and adjusts the spacing and magnitude according to the set temperature; S4, Sensor installed in cooling water circuit mode: The controller opens the liquid solenoid valve every once in a while. When the detected water temperature is higher than the set temperature value, the valve opens, but when the temperature is lower than the set temperature value, the valve closes. S5. The controller uses surface or water temperature sensors and flow sensors to collect temperature and flow data in real time. It monitors the data according to the set upper and lower temperature limits and the lower flow limit. When the real-time temperature or flow exceeds the limit, the controller issues an alarm signal. S6. The actual temperature of the mold surface or water return water is continuously collected by the mold surface temperature sensor or water circuit temperature sensor, and compared with the set temperature to form a temperature curve with the target temperature as the axis. The collection period and duration are adjustable.

5. The control method of the pulse cooling and heating intelligent mold temperature controller according to claim 4, characterized in that, The real-time temperature is acquired periodically at a frequency of 20ms or higher, resulting in time-series temperature data with time resolution.

6. The control method of the pulse cooling and heating intelligent mold temperature controller according to claim 4, characterized in that, The measured temperature and flow rate in step S5 are compared with the preset threshold to determine whether the loop is in a condition that meets the heat transfer requirements or in an abnormal condition, and to obtain the loop operating condition status identifier; the loop operating condition status identifier includes normal, warning and fault.

7. The control method of the pulse cooling and heating intelligent mold temperature controller according to claim 4, characterized in that, As described in step S6, by setting the target temperature of the mold required for molding, the controller obtains a real-time temperature curve by continuously collecting the measured temperature with the required coordinates and length.

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