A method and system for temperature control at the feed port of an injection molding machine

Abstract

This invention discloses a temperature control method and system for the feed port of an injection molding machine. It calculates a target temperature control value based on empirical values ​​and the set temperature of the feed port temperature measuring point; it then determines whether the real-time temperature of the feed port temperature measuring point is within the target temperature control range. If so, it enters a segmented PWM pulse width modulation program, including: adjusting the percentage of the water valve output time corresponding to the previous temperature detection cycle using the temperature change value of the feed port temperature measuring point corresponding to the previous temperature detection cycle, and controlling the water valve output through the adjusted percentage. In other words, this invention adjusts the percentage of the water valve output time corresponding to the previous temperature detection cycle using the temperature change value of the feed port temperature measuring point corresponding to the previous temperature detection cycle in each temperature detection cycle, and calculates the target temperature control value based on empirical values. This achieves segmented PWM pulse width modulation of the target temperature control value, reducing fluctuations in the actual temperature of the feed port.

Description

Technical Field

[0001] This invention relates to the field of injection molding machines, and more particularly to a method and system for temperature control at the discharge port of an injection molding machine. Background Technology

[0002] Currently, in the field of all-electric injection molding machines, the temperature of the inner wall of the barrel is controlled by the temperature detected at the discharge port temperature measuring point. However, the discharge port temperature measuring point is not located inside the inner wall of the barrel. Therefore, directly controlling the temperature of the inner wall of the barrel by the temperature monitored at the discharge port temperature measuring point (there is a large temperature difference between the two) cannot achieve precise temperature control.

[0003] Furthermore, the current control method for the water valve at the injection molding machine's discharge port is relatively simple, controlling the discharge port temperature merely by opening and closing the valve. The discharge port temperature control function screen includes settings for the set discharge port temperature and the lower deviation. When the discharge port temperature reaches the set temperature, the water valve opens; when the temperature drops to the lower deviation temperature, the water valve closes (for example, if the set discharge port temperature is 50℃ and the lower deviation is 2℃, a control signal is output when the actual discharge port temperature is greater than or equal to 50℃, and the water valve opens; when the actual temperature is less than or equal to the lower deviation temperature of 48℃, the control signal stops, and the water valve closes). This on / off control method cannot stabilize the discharge port temperature within a certain range, failing to precisely control the discharge port temperature, affecting the material temperature, and consequently impacting the customer's production. In actual operation, if the lower deviation is set too small, the water valve will open when the temperature at the discharge port reaches the set temperature. At this time, the temperature is still rising and there will be overshoot. When the temperature at the discharge port drops to the lower deviation temperature (lower deviation temperature = set temperature - lower deviation), the water valve will close. At this time, the temperature will drop significantly, and the temperature fluctuation will be large, which will affect the product quality.

[0004] Specifically, current industry technology has two problems: First, there is a certain deviation between the temperature measuring point at the discharge port and the actual position on the inner wall of the barrel, which is not the location truly important in the process, so the current temperature control is not precise. Second, if customers use the aforementioned on / off temperature control method, the actual temperature at the discharge port will be unstable, fluctuating significantly, which can easily lead to instability in the storage time and remaining quantity, affecting the customer's product quality. For example, a customer experienced inconsistent product dimensions during production, which was found to be caused by unstable injection quantity. After in-depth analysis, it was discovered that the large fluctuations in the actual temperature at the discharge port caused the remaining quantity to change accordingly, resulting in a decrease in the repeatability of product dimensions. Summary of the Invention

[0005] To accurately and stably control the actual temperature at the injection port, thereby indirectly and accurately controlling the temperature of the inner wall of the barrel, and thus stabilizing the injection residue and improving product quality for customers, this invention proposes a temperature control method for the injection port of an injection molding machine, comprising:

[0006] Obtain the empirical value corresponding to the injection molding machine model to be controlled; the empirical value is the deviation between the temperature at the discharge port temperature measuring point and the temperature of the inner wall of the barrel.

[0007] Set temperature control parameters; the temperature control parameters include: temperature detection cycle, target temperature control value, and target temperature control range; wherein, the target temperature control value is obtained by empirical value and the set temperature of the feeding port temperature measuring point, the lower limit of the target temperature control range is the lower deviation temperature of the target temperature control value, and the upper limit of the target temperature control range is the upper deviation temperature of the target temperature control value.

[0008] Monitor the real-time temperature of the temperature measuring point at the material outlet of the injection molding machine to be controlled;

[0009] Determine whether the real-time temperature of the feed port temperature measuring point is within the target temperature control range. If so, enter the segmented PWM pulse width modulation program, including: using the PWM pulse width modulation method to adjust the percentage of the water valve output time corresponding to the feed port temperature measuring point in the previous temperature detection cycle, and controlling the water valve output through the adjusted percentage; when the current temperature detection cycle is the first temperature detection cycle, control the water valve output through the initial duty cycle.

[0010] Furthermore, the temperature control method further includes:

[0011] Determine whether the real-time temperature at the feeding port temperature measuring point is within the target temperature control range. If not, determine whether the real-time temperature at the feeding port temperature measuring point is less than the lower limit of the target temperature control range. If yes, enter the segmented PWM pulse width modulation program when the real-time temperature reaches the lower deviation temperature. If no, open the water valve output and enter the segmented PWM pulse width modulation program when the real-time temperature at the feeding port temperature measuring point drops to the upper limit of the target temperature control range.

[0012] Furthermore, the segmented PWM pulse width modulation program specifically includes:

[0013] The temperature change value of the feed port temperature measuring point corresponding to the previous temperature detection cycle is obtained. When the temperature change value is positive and greater than the preset value, the output time of the water valve in the current temperature detection cycle is increased by the preset increase value. The percentage of the water valve output time in the current temperature detection cycle is adjusted based on the increased output time, and the output of the water valve is controlled by the adjusted percentage in the current temperature detection cycle.

[0014] When the temperature change value is negative and its absolute value is greater than the preset value, the output time of the water valve in the current temperature detection cycle is reduced by the preset reduction value, and the percentage of the water valve output time in the current temperature detection cycle is adjusted based on the reduced output time, and the output of the water valve is controlled by the adjusted percentage in the current temperature detection cycle.

[0015] When the absolute value of the temperature change is less than the preset value, the percentage of the water valve output time corresponding to the current temperature detection cycle remains unchanged.

[0016] Furthermore, the formula for calculating the percentage of time the water valve outputs is as follows:

[0017] D = Ton / T;

[0018] Where Ton represents the output time of the water valve within one temperature detection cycle, T represents the temperature detection cycle, and D represents the percentage of the water valve's output time within one temperature detection cycle.

[0019] Furthermore, the method for obtaining the experience value includes:

[0020] Multiple sets of environmental operating data are set, and the discharge port temperature and barrel inner wall temperature are tested on different models of injection molding machines based on each set of environmental operating data to obtain the temperature difference value of each model of injection molding machine under each set of environmental operating data; the temperature difference value is the difference between the discharge port temperature and the barrel inner wall temperature; the average value of the corresponding temperature difference value for each model is obtained as the empirical value corresponding to that model of injection molding machine.

[0021] Furthermore, the environmental operating data includes: the set temperature at the tail end of the barrel and the set temperature at the discharge port temperature measuring point.

[0022] This invention also proposes a temperature control system for the feed port of an injection molding machine, comprising:

[0023] The testing module is used to obtain the empirical values ​​corresponding to the injection molding machine model to be controlled; the empirical values ​​are the deviation between the temperature at the material outlet temperature measuring point and the temperature of the inner wall of the barrel.

[0024] The parameter setting module is used to set temperature control parameters. The temperature control parameters include: temperature detection cycle, target temperature control value, and target temperature control range. The target temperature control value is obtained through empirical values ​​and the set temperature of the feeding port temperature measuring point. The lower limit of the target temperature control range is the lower deviation temperature of the target temperature control value, and the upper limit of the target temperature control range is the upper deviation temperature of the target temperature control value.

[0025] The monitoring module is used to monitor the real-time temperature of the temperature measuring point at the material outlet of the injection molding machine to be controlled;

[0026] The control module is used to enter a segmented PWM pulse width modulation program when the real-time temperature at the feed port temperature measuring point is within the target temperature control range. This program includes: adjusting the percentage of the water valve output time corresponding to the current temperature detection cycle using the temperature change value at the feed port temperature measuring point corresponding to the previous temperature detection cycle through PWM pulse width modulation, and controlling the water valve output through the adjusted percentage; when the current temperature detection cycle is the first temperature detection cycle, the water valve output is controlled through the initial duty cycle.

[0027] Furthermore, the control module is specifically used to: determine whether the real-time temperature of the feeding port temperature measuring point is within the target temperature control range; if not, determine whether the real-time temperature of the feeding port temperature measuring point is less than the lower limit of the target temperature control range; if yes, enter the segmented PWM pulse width modulation program when the real-time temperature reaches the lower deviation temperature; if no, open the water valve output, and enter the segmented PWM pulse width modulation program when the real-time temperature of the feeding port temperature measuring point drops to the upper limit of the target temperature control range.

[0028] Furthermore, the segmented PWM pulse width modulation program specifically includes:

[0029] The temperature change value of the feed port temperature measuring point corresponding to the previous temperature detection cycle is obtained. When the temperature change value is positive and greater than the preset value, the output time of the water valve in the current temperature detection cycle is increased by the preset increase value. The percentage of the water valve output time in the current temperature detection cycle is adjusted based on the increased output time, and the output of the water valve is controlled by the adjusted percentage in the current temperature detection cycle.

[0030] When the temperature change value is negative and its absolute value is greater than the preset value, the output time of the water valve in the current temperature detection cycle is reduced by the preset reduction value, and the percentage of the water valve output time in the current temperature detection cycle is adjusted based on the reduced output time, and the output of the water valve is controlled by the adjusted percentage in the current temperature detection cycle.

[0031] When the absolute value of the temperature change is less than the preset value, the percentage of the water valve output time corresponding to the current temperature detection cycle remains unchanged.

[0032] Furthermore, the testing module is specifically used to set multiple sets of environmental operating data, and to test the discharge port temperature and the barrel inner wall temperature based on each set of environmental operating data on different models of injection molding machines, so as to obtain the temperature difference value of each model of injection molding machine under each set of environmental operating data; the temperature difference value is the difference between the discharge port temperature and the barrel inner wall temperature; the average value of the corresponding temperature difference value for each model is obtained as the empirical value corresponding to that model of injection molding machine.

[0033] Compared with the prior art, the present invention has at least the following beneficial effects:

[0034] (1) This invention obtains the empirical value corresponding to the injection molding machine model to be controlled; calculates the target temperature control value by combining the empirical value with the set temperature of the discharge port temperature measuring point; determines whether the real-time temperature of the discharge port temperature measuring point is within the target temperature control range; if so, it enters the segmented PWM pulse width modulation program, including: adjusting the percentage of the water valve output time corresponding to the current temperature detection cycle by using the temperature change value of the discharge port temperature measuring point corresponding to the previous temperature detection cycle through the PWM pulse width modulation method, and controlling the output of the water valve by the adjusted percentage; that is, in each temperature detection cycle, this invention uses the temperature change value of the discharge port temperature measuring point corresponding to the previous temperature detection cycle to adjust the percentage of the water valve output time corresponding to the current temperature detection cycle, and calculates the target temperature control value based on the empirical value, thereby realizing segmented PWM pulse width modulation of the target temperature control value and reducing the fluctuation of the actual temperature of the discharge port;

[0035] (2) The present invention calculates the target temperature control value based on empirical values, so that the actual temperature of the inner wall of the barrel is as close as possible to the target temperature control value, and performs segmented PWM pulse width modulation on the target temperature control value based on the temperature detection cycle, thereby achieving accurate and stable control of the actual temperature of the discharge port, and indirectly achieving accurate and stable control of the temperature of the inner wall of the barrel, stabilizing the injection residual amount, and improving the product quality of customers.

[0036] (3) By setting multiple sets of environmental operating data, the present invention tests the discharge port temperature and barrel inner wall temperature on different models of injection molding machines based on each set of environmental operating data, obtains the temperature difference value of each model of injection molding machine under each set of environmental operating data, and obtains the average value of the corresponding temperature difference value of each model as the corresponding empirical value of the injection molding machine, thereby improving the accuracy of the empirical value and thus improving the control accuracy of the actual discharge port temperature. Attached Figure Description

[0037] Figure 1 A flowchart of a temperature control method for the feed port of an injection molding machine;

[0038] Figure 2 This is a schematic diagram of a temperature control system module for the feed port of an injection molding machine;

[0039] Figure 3 The waveform of temperature change using the existing on / off temperature control method;

[0040] Figure 4 The temperature change waveform diagram is shown using the temperature control method of the present invention. Detailed Implementation

[0041] The following are specific embodiments of the present invention, which are described in conjunction with the accompanying drawings. However, the present invention is not limited to these embodiments.

[0042] Example 1

[0043] In this embodiment, the discharge port refers to the point where the plastic granules enter the mold; the storage port refers to molten plastic granules in preparation for the next injection molding step; and the injection residue refers to the amount of plastic that fails to be injected into the mold during the injection molding process. Since the temperature, stability, and fluctuation range of the discharge port all affect the injection residue, this invention uses empirical values ​​to precisely control the target temperature, ensuring that the discharge port temperature always fluctuates within the target temperature control range corresponding to the target temperature control value. This precise and stable control of the discharge port temperature indirectly and precisely controls the temperature of the inner wall of the barrel, significantly improving the quality of the injection-molded product. Figure 1 As shown, in order to accurately and stably control the actual temperature of the feed port, this invention proposes a temperature control method for the feed port of an injection molding machine, comprising:

[0044] Obtain the empirical value corresponding to the injection molding machine model to be controlled; the empirical value is the deviation between the temperature at the discharge port temperature measuring point and the temperature of the inner wall of the barrel.

[0045] The methods for obtaining the experience value include:

[0046] Multiple sets of environmental operating data are set, and the discharge port temperature and barrel inner wall temperature are tested on different models of injection molding machines based on each set of environmental operating data to obtain the temperature difference value of each model of injection molding machine under each set of environmental operating data; the temperature difference value is the difference between the discharge port temperature and the barrel inner wall temperature; the average value of the corresponding temperature difference value for each model is obtained as the empirical value corresponding to that model of injection molding machine.

[0047] It should be noted that, in this embodiment, obtaining empirical values ​​requires the addition of thermocouples to the injection molding machine of the model to be tested. Specifically, a patch thermocouple is placed on the inner wall of the barrel as data source 2; the thermocouple originally set at the discharge port serves as data source 1 (i.e., the discharge port temperature measurement point). The discharge port temperature is obtained through data source 1, and the barrel inner wall temperature is obtained through data source 2.

[0048] The environmental operating data includes: the set temperature at the tail end of the barrel and the set temperature at the discharge port temperature measuring point; it may also include the set temperature of the cooling water.

[0049] The injection molding machine models provided in this embodiment include, but are not limited to, the models listed in Table 1 below:

[0050]

[0051]

[0052] In this embodiment, the discharge port temperature and barrel inner wall temperature were tested using injection molding machines of models 80 and 1400 listed in Table 1. The results are shown in Table 2 below:

[0053]

[0054] From Table 2 above, we can conclude that:

[0055] Experience points 80 = (3.3 + 3.7 + 3.9 + 2.8 + 3.9 + 2.5) / 6 = 3.35;

[0056] In the formula, empirical value 80 This represents the empirical value for an 80 injection molding machine. The calculation of the corresponding empirical value for a 1400 injection molding machine is the same as that for an 80 injection molding machine.

[0057] It should be explained that most older injection molding machine models do not have thermocouples installed in the inner wall of the barrel. Redesigning all injection molding machine models to add thermocouples would require a huge amount of manpower and resources, and the workload would be enormous. Therefore, this invention only adds thermocouples to the injection molding machine model under test to obtain the temperature difference value under different operating conditions, and then obtains the corresponding empirical value for that model. This avoids redesigning all injection molding machines and obtains the target temperature control value through empirical values, which reduces the modification cost and improves the control accuracy of the barrel inner wall temperature.

[0058] This invention sets multiple sets of environmental operating data and tests the discharge port temperature and barrel inner wall temperature on different injection molding machine models based on each set of environmental operating data. It obtains the temperature difference value of each injection molding machine model under each set of environmental operating data, and obtains the average value of the corresponding temperature difference value for each model as the corresponding empirical value for that injection molding machine model. This improves the accuracy of the empirical value and thus improves the control precision of the actual discharge port temperature.

[0059] Set temperature control parameters; the temperature control parameters include: temperature detection cycle, target temperature control value, and target temperature control range; wherein, the target temperature control value is obtained by empirical value and the set temperature of the feeding port temperature measuring point, the lower limit of the target temperature control range is the lower deviation temperature of the target temperature control value, and the upper limit of the target temperature control range is the upper deviation temperature of the target temperature control value.

[0060] Specifically, assuming the temperature deviation between the discharge port temperature measuring point and the inner wall temperature of the barrel is 3℃ (i.e., the inner wall temperature of the barrel is 3℃ higher than the temperature of the discharge port temperature measuring point), and the set temperature of the discharge port temperature measuring point is 50℃, then the target temperature control value is equal to 53℃.

[0061] The following are specific examples:

[0062] The target temperature control value is set to 50℃, with a lower deviation of 2℃, an upper deviation of 3℃, a temperature detection cycle of 20 seconds, and a preset value of 0.1℃. Therefore, the target temperature control range is [48℃, 53℃].

[0063] Monitor the real-time temperature of the temperature measuring point at the material outlet of the injection molding machine to be controlled;

[0064] Determine whether the real-time temperature of the feed port temperature measuring point is within the target temperature control range [48℃, 53℃]. If so, enter the segmented PWM pulse width modulation program, including: using the temperature change value of the feed port temperature measuring point corresponding to the previous temperature detection cycle to adjust the percentage of the water valve output time corresponding to the current temperature detection cycle through the PWM pulse width modulation method, and controlling the output of the water valve through the adjusted percentage; when the current temperature detection cycle is the first temperature detection cycle, control the output of the water valve through the initial duty cycle.

[0065] The temperature control method further includes:

[0066] Determine if the real-time temperature at the discharge port temperature measuring point is within the target temperature control range [48℃, 53℃]. If not, determine if the real-time temperature at the discharge port temperature measuring point is less than the lower limit of the target temperature control range, 48℃. If yes (i.e., the real-time temperature at the discharge port temperature measuring point is less than the lower limit of the target temperature control range), enter the segmented PWM pulse width modulation program when the real-time temperature reaches the lower deviation temperature of 48℃. If no (i.e., the real-time temperature at the discharge port temperature measuring point is greater than the upper limit of the target temperature control range), open the water valve output (open the water valve in full-pass mode, i.e., the duty cycle is 1, with a maximum duty cycle of 1 and a minimum of 0), and enter the segmented PWM pulse width modulation program when the real-time temperature at the discharge port temperature measuring point drops to the upper limit of the target temperature control range, 53℃.

[0067] The segmented PWM pulse width modulation program specifically includes:

[0068] The temperature change value of the feed port temperature measuring point corresponding to the previous temperature detection cycle is obtained. When the temperature change value is positive and it is greater than the preset value of 0.1℃, the output time of the water valve in the current temperature detection cycle is increased by the preset increment value (the preset increment value is 2 seconds in this embodiment). The percentage of the water valve output time in the current temperature detection cycle is adjusted based on the increased output time, and the output of the water valve is controlled by the adjusted percentage in the current temperature detection cycle.

[0069] When the temperature change value is negative and its absolute value is greater than the preset value of 0.1℃, the output time of the water valve in the current temperature detection cycle is reduced by the preset reduction value (the preset increase value in this embodiment is -2 seconds). Based on the reduced output time, the percentage of the water valve output time in the current temperature detection cycle is adjusted, and the output of the water valve is controlled by the adjusted percentage in the current temperature detection cycle.

[0070] It should be noted that the water valve output control in this embodiment is divided into ten levels: Level 1: 2 / 18 (i.e., the water valve is open for 2 seconds and closed for 18 seconds); Level 2: 4 / 16; Level 3: 6 / 14... Level 9: 18 / 2; Level 10: 20 / 0 (i.e., the water valve is fully open).

[0071] When the absolute value of the temperature change is less than the preset value, the percentage of the water valve output time corresponding to the current temperature detection cycle remains unchanged until the temperature is lower than the lower deviation temperature, at which point the water valve closes.

[0072] The formula for calculating the percentage of time the water valve outputs is:

[0073] D = Ton / T;

[0074] Where Ton represents the output time of the water valve within one temperature detection cycle, T represents the temperature detection cycle, and D represents the percentage of the water valve's output time within one temperature detection cycle.

[0075] Figure 3 The temperature change waveform is shown in the example obtained by setting the temperature at the tail end of the barrel to 180°C (heating temperature at the tail end of the barrel), the temperature at the discharge port measuring point to 50°C, and the cooling water to 15°C.

[0076] Figure 4 The temperature change waveform obtained in this embodiment is based on an experiment with the following parameters: the set temperature at the tail end of the barrel is 180°C, the target temperature control value is 50°C, the cooling water temperature is 15°C, the upper deviation is 3°C, the lower deviation is 2°C, the temperature detection cycle is 20s, and the preset value is 0.1°C.

[0077] from Figure 3 (The horizontal axis represents time, and the vertical axis represents temperature.) It can be seen that the actual temperature at the discharge port is as high as 50.1℃ and as low as 44.6℃, with a difference of 5.5℃ between the two.

[0078] from Figure 4 (The horizontal axis represents time, and the vertical axis represents temperature.) It can be seen that the actual temperature at the discharge port ranged from a high of 48.3℃ to a low of 46.9℃, a difference of 1.4℃. Figure 3 Compared to the previous year, the temperature deviation was reduced by 4.1℃, a reduction of 74.5%, indicating a very good control effect.

[0079] This invention obtains the empirical value corresponding to the injection molding machine model to be controlled; calculates the target temperature control value based on the empirical value and the set temperature of the discharge port temperature measuring point; determines whether the real-time temperature of the discharge port temperature measuring point is within the target temperature control range; if so, it enters a segmented PWM pulse width modulation program, including: adjusting the percentage of the water valve output time corresponding to the previous temperature detection cycle using the temperature change value of the discharge port temperature measuring point corresponding to the previous temperature detection cycle through PWM pulse width modulation, and controlling the water valve output through the adjusted percentage; that is, in each temperature detection cycle, this invention uses the temperature change value of the discharge port temperature measuring point corresponding to the previous temperature detection cycle to adjust the percentage of the water valve output time corresponding to the current temperature detection cycle, and calculates the target temperature control value based on the empirical value, thus realizing segmented PWM pulse width modulation of the target temperature control value and reducing the fluctuation of the actual temperature of the discharge port.

[0080] Example 2

[0081] like Figure 2 As shown, the present invention also proposes a temperature control system for the feed port of an injection molding machine, comprising:

[0082] The testing module is used to obtain the empirical values ​​corresponding to the injection molding machine model to be controlled; the empirical values ​​are the deviation between the temperature at the material outlet temperature measuring point and the temperature of the inner wall of the barrel.

[0083] The testing module is specifically used to set multiple sets of environmental operating data, and to test the discharge port temperature and the barrel inner wall temperature on different models of injection molding machines based on each set of environmental operating data, so as to obtain the temperature difference value of each model of injection molding machine under each set of environmental operating data; the temperature difference value is the difference between the discharge port temperature and the barrel inner wall temperature; the average value of the corresponding temperature difference value for each model is obtained as the empirical value corresponding to that model of injection molding machine.

[0084] The parameter setting module is used to set temperature control parameters. The temperature control parameters include: temperature detection cycle, target temperature control value, and target temperature control range. The target temperature control value is obtained through empirical values ​​and the set temperature of the feeding port temperature measuring point. The lower limit of the target temperature control range is the lower deviation temperature of the target temperature control value, and the upper limit of the target temperature control range is the upper deviation temperature of the target temperature control value.

[0085] The monitoring module is used to monitor the real-time temperature of the temperature measuring point at the material outlet of the injection molding machine to be controlled;

[0086] The control module is used to enter a segmented PWM pulse width modulation program when the real-time temperature at the feed port temperature measuring point is within the target temperature control range. This program includes: adjusting the percentage of the water valve output time corresponding to the current temperature detection cycle using the temperature change value at the feed port temperature measuring point corresponding to the previous temperature detection cycle through PWM pulse width modulation, and controlling the water valve output through the adjusted percentage; when the current temperature detection cycle is the first temperature detection cycle, the water valve output is controlled through the initial duty cycle.

[0087] The control module is specifically used to: determine whether the real-time temperature of the temperature measuring point at the discharge port is within the target temperature control range; if not, determine whether the real-time temperature of the temperature measuring point at the discharge port is less than the lower limit of the target temperature control range; if yes, enter the segmented PWM pulse width modulation program when the real-time temperature reaches the lower deviation temperature; if no, open the water valve output, and enter the segmented PWM pulse width modulation program when the real-time temperature of the temperature measuring point at the discharge port drops to the upper limit of the target temperature control range.

[0088] The segmented PWM pulse width modulation program specifically includes:

[0089] The temperature change value of the feed port temperature measuring point corresponding to the previous temperature detection cycle is obtained. When the temperature change value is positive and greater than the preset value, the output time of the water valve in the current temperature detection cycle is increased by the preset increase value. The percentage of the water valve output time in the current temperature detection cycle is adjusted based on the increased output time, and the output of the water valve is controlled by the adjusted percentage in the current temperature detection cycle.

[0090] When the temperature change value is negative and its absolute value is greater than the preset value, the output time of the water valve in the current temperature detection cycle is reduced by the preset reduction value, and the percentage of the water valve output time in the current temperature detection cycle is adjusted based on the reduced output time, and the output of the water valve is controlled by the adjusted percentage in the current temperature detection cycle.

[0091] When the absolute value of the temperature change is less than the preset value, the percentage of the water valve output time corresponding to the current temperature detection cycle remains unchanged.

[0092] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indication will also change accordingly.

[0093] Furthermore, in this invention, descriptions involving terms such as "first," "second," and "a" are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0094] In this invention, unless otherwise explicitly specified and limited, the terms "connection," "fixed," etc., should be interpreted broadly. For example, "fixed" can mean a fixed connection, a detachable connection, or an integral part; it can mean a mechanical connection or an electrical connection; it can mean a direct connection or an indirect connection through an intermediate medium; it can mean the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0095] Furthermore, the technical solutions of the various embodiments of the present invention can be combined with each other, but only if they are feasible for those skilled in the art. If the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

Claims

1. A method for temperature control at the feed inlet of an injection molding machine, characterized in that, include: Obtain the experience values ​​corresponding to the injection molding machine model to be controlled; The empirical value is the deviation between the temperature at the feed inlet temperature measuring point and the temperature of the inner wall of the barrel. The method for obtaining the empirical value includes: setting multiple sets of environmental operating data, testing the discharge port temperature and the barrel inner wall temperature on different models of injection molding machines based on each set of environmental operating data, and obtaining the temperature difference value of each model of injection molding machine under each set of environmental operating data; the temperature difference value is the difference between the discharge port temperature and the barrel inner wall temperature; and obtaining the average value of the corresponding temperature difference value for each model as the empirical value corresponding to that model of injection molding machine. Set temperature control parameters; the temperature control parameters include: temperature detection cycle, target temperature control value, and target temperature control range; wherein, the target temperature control value is obtained by empirical value and the set temperature of the feeding port temperature measuring point, the lower limit of the target temperature control range is the lower deviation temperature of the target temperature control value, and the upper limit of the target temperature control range is the upper deviation temperature of the target temperature control value. Monitor the real-time temperature of the temperature measuring point at the material outlet of the injection molding machine to be controlled; Determine whether the real-time temperature of the feed port temperature measuring point is within the target temperature control range. If so, enter the segmented PWM pulse width modulation program, including: using the PWM pulse width modulation method to adjust the percentage of the water valve output time corresponding to the feed port temperature measuring point in the previous temperature detection cycle, and controlling the water valve output through the adjusted percentage; when the current temperature detection cycle is the first temperature detection cycle, control the water valve output through the initial duty cycle.

2. The temperature control method for the feed inlet of an injection molding machine according to claim 1, characterized in that, The temperature control method further includes: Determine whether the real-time temperature at the feeding port temperature measuring point is within the target temperature control range. If not, determine whether the real-time temperature at the feeding port temperature measuring point is less than the lower limit of the target temperature control range. If yes, enter the segmented PWM pulse width modulation program when the real-time temperature reaches the lower deviation temperature. If no, open the water valve output and enter the segmented PWM pulse width modulation program when the real-time temperature at the feeding port temperature measuring point drops to the upper limit of the target temperature control range.

3. The temperature control method for the feed inlet of an injection molding machine according to claim 2, characterized in that, The segmented PWM pulse width modulation program specifically includes: The temperature change value of the feed port temperature measuring point corresponding to the previous temperature detection cycle is obtained. When the temperature change value is positive and greater than the preset value, the output time of the water valve in the current temperature detection cycle is increased by the preset increase value. The percentage of the water valve output time in the current temperature detection cycle is adjusted based on the increased output time, and the output of the water valve is controlled by the adjusted percentage in the current temperature detection cycle. When the temperature change value is negative and its absolute value is greater than the preset value, the output time of the water valve in the current temperature detection cycle is reduced by the preset reduction value, and the percentage of the water valve output time in the current temperature detection cycle is adjusted based on the reduced output time, and the output of the water valve is controlled by the adjusted percentage in the current temperature detection cycle. When the absolute value of the temperature change is less than the preset value, the percentage of the water valve output time corresponding to the current temperature detection cycle remains unchanged.

4. The temperature control method for the feed inlet of an injection molding machine according to claim 3, characterized in that, The formula for calculating the percentage of time the water valve outputs is: ； in, This indicates the output time of the water valve within one temperature detection cycle. Indicates the temperature detection cycle. This indicates the percentage of time the water valve is output within a temperature detection cycle.

5. A temperature control method for the feed inlet of an injection molding machine according to claim 4, characterized in that, The environmental operating data includes: the set temperature at the tail end of the barrel and the set temperature at the discharge port temperature measuring point.

6. A temperature control system for the feed inlet of an injection molding machine, characterized in that, include: The testing module is used to obtain the empirical values ​​corresponding to the injection molding machine model to be controlled; the empirical values ​​are the deviation between the temperature at the material outlet temperature measuring point and the temperature of the inner wall of the barrel. The testing module is specifically used to set multiple sets of environmental operating data, and to test the discharge port temperature and the barrel inner wall temperature on different models of injection molding machines based on each set of environmental operating data, so as to obtain the temperature difference value of each model of injection molding machine under each set of environmental operating data; the temperature difference value is the difference between the discharge port temperature and the barrel inner wall temperature; the average value of the corresponding temperature difference value for each model is obtained as the empirical value corresponding to that model of injection molding machine. The parameter setting module is used to set temperature control parameters; The temperature control parameters include: temperature detection cycle, target temperature control value, and target temperature control range; wherein, the target temperature control value is obtained through empirical value and the set temperature of the feeding port temperature measuring point, the lower limit of the target temperature control range is the lower deviation temperature of the target temperature control value, and the upper limit of the target temperature control range is the upper deviation temperature of the target temperature control value. The monitoring module is used to monitor the real-time temperature of the temperature measuring point at the material outlet of the injection molding machine to be controlled; The control module is used to enter a segmented PWM pulse width modulation program when the real-time temperature at the feed port temperature measuring point is within the target temperature control range. This program includes: adjusting the percentage of the water valve output time corresponding to the current temperature detection cycle using the temperature change value at the feed port temperature measuring point corresponding to the previous temperature detection cycle through PWM pulse width modulation, and controlling the water valve output through the adjusted percentage; when the current temperature detection cycle is the first temperature detection cycle, the water valve output is controlled through the initial duty cycle.

7. A temperature control system for the feed inlet of an injection molding machine according to claim 6, characterized in that, The control module is specifically used to: determine whether the real-time temperature of the temperature measuring point at the discharge port is within the target temperature control range; if not, determine whether the real-time temperature of the temperature measuring point at the discharge port is less than the lower limit of the target temperature control range; if yes, enter the segmented PWM pulse width modulation program when the real-time temperature reaches the lower deviation temperature; if no, open the water valve output, and enter the segmented PWM pulse width modulation program when the real-time temperature of the temperature measuring point at the discharge port drops to the upper limit of the target temperature control range.

8. A temperature control system for the feed inlet of an injection molding machine according to claim 7, characterized in that, The segmented PWM pulse width modulation program specifically includes: The temperature change value of the feed port temperature measuring point corresponding to the previous temperature detection cycle is obtained. When the temperature change value is positive and greater than the preset value, the output time of the water valve in the current temperature detection cycle is increased by the preset increase value. The percentage of the water valve output time in the current temperature detection cycle is adjusted based on the increased output time, and the output of the water valve is controlled by the adjusted percentage in the current temperature detection cycle. When the temperature change value is negative and its absolute value is greater than the preset value, the output time of the water valve in the current temperature detection cycle is reduced by the preset reduction value, and the percentage of the water valve output time in the current temperature detection cycle is adjusted based on the reduced output time, and the output of the water valve is controlled by the adjusted percentage in the current temperature detection cycle. When the absolute value of the temperature change is less than the preset value, the percentage of the water valve output time corresponding to the current temperature detection cycle remains unchanged.

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