Closed-loop parameter adjusting method for injection molding process

Abstract

The invention discloses an injection molding process closed-loop parameter adjustment method which comprises the following steps: S1, collecting real-time injection molding data to form a real-time cavity pressure curve; s2, the mold intelligent terminal compares the real-time cavity pressure curve with the standard cavity pressure curve, compares feature point numerical values, calculates the difference between the real-time cavity pressure curve and the standard cavity pressure curve and judges the difference, and if the difference is within a preset range, injection molding continues to be conducted according to the current injection molding process parameters; if the difference is not within the preset range, executing the step S3; s3, the mold intelligent terminal automatically adjusts injection molding process parameters according to the difference and the injection molding process parameters corresponding to the current real-time cavity pressure curve and inputs the injection molding process parameters into the injection molding machine, and the injection molding machine carries out injection molding again; and S4, the steps S1-S3 are repeated until the difference between the real-time cavity pressure curve and the standard cavity pressure curve is within a preset range, and closed-loop control is formed. According to the invention, the injection molding process is digitalized, closed-loop control is realized, the efficiency is high, the precision is high, and the systematization degree is high.

Description

Technical Field

[0001] The invention belongs to the field of injection molding process control, and specifically relates to a closed-loop parameter adjustment method for an injection molding process. Background Art

[0002] In the prior art, the adjustment of injection molding machine parameters depends on the experience and judgment of the operator. When manually adjusting the parameters, the quality of the injection molded product and the rationality of the injection molding process are generally judged based on the evaluation of the weight and size of the injection molded product. If the injection molded product is not qualified, the injection molding process parameters are adjusted and the injection molded product is evaluated and judged after another injection. The high degree of manual participation and the different experience and skill levels of different operators can easily lead to inconsistency in the adjustment results and subjective judgment errors, and the efficiency is low, the accuracy is poor, and it cannot be managed systematically.

[0003] In view of this, the present invention is proposed. Summary of the invention

[0004] The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art and provide a closed-loop parameter adjustment method for an injection molding process, which can automatically adjust the injection molding parameters with consistent standards, simple quantification, easy closed-loop, and reduced labor.

[0005] In order to solve the above technical problems, the basic concept of the technical solution adopted by the present invention is:

[0006] A closed-loop parameter adjustment method for an injection molding process comprises the following steps:

[0007] S1. The mold intelligent terminal collects real-time injection molding data to form a real-time cavity pressure curve;

[0008] S2. The mold intelligent terminal compares the real-time cavity pressure curve and the standard cavity pressure curve, and adopts the method of comparing characteristic points. By comparing the values ​​of the characteristic points of the cavity pressure curve, the difference between the two is calculated and judged:

[0009] If the difference is within the preset range, the injection molding will continue according to the current injection molding process parameters;

[0010] If the difference is not within the preset range, execute step S3;

[0011] S3. The mold intelligent terminal automatically adjusts the injection molding process parameters according to the difference and the injection molding process parameters corresponding to the current real-time cavity pressure curve and inputs them into the injection molding machine, and the injection molding machine performs injection molding again;

[0012] S4, repeating steps S1-S3 until the difference between the real-time cavity pressure curve and the standard cavity pressure curve is within a preset range, thereby forming a closed-loop control.

[0013] By collecting real-time injection data during each injection to form a real-time cavity pressure curve and comparing it with the standard cavity pressure curve, it can be determined whether the difference between the two pressure curves is within a preset range.

[0014] If the difference is not within the preset range, it means that the injection molded product formed by this injection molding is unqualified, and the injection molding process parameters need to be adjusted and the injection molding is carried out using the adjusted injection molding process parameters until the comparison difference between the real-time cavity pressure curve after the injection molding process parameters are adjusted and the standard cavity pressure curve is within the preset range. The injection molding machine continues to produce under the injection molding process parameters corresponding to the current real-time cavity pressure curve.

[0015] If the difference is within the preset range, it means that the injection molded product formed by this injection molding is qualified, the current injection molding process parameters are reasonable, and production can continue under the current injection molding process parameters.

[0016] The injection molding process parameters are adjusted by the mold intelligent terminal based on the difference between the current real-time cavity pressure curve and the standard cavity pressure curve and the injection molding process parameters corresponding to the current real-time cavity pressure curve. The mold intelligent terminal automatically adjusts the injection molding process parameters and inputs them into the injection molding machine.

[0017] The mold intelligent terminal automatically collects real-time injection molding data to form a real-time cavity pressure curve, compares the real-time cavity pressure curve with the standard cavity pressure curve, and determines whether the injection molding process parameters need to be adjusted and how to adjust the injection molding process parameters based on the comparison results, and inputs the adjusted injection molding process parameters into the injection molding machine. When the injection molding machine adopts the adjusted injection molding process parameters for injection molding, real-time injection molding data is collected to form a real-time cavity pressure curve. A new round of steps are all automatically completed by the mold intelligent terminal, which can realize closed-loop control and completely complete the execution and adjustment of the injection molding work until continuous production is met. There is no need for manual intervention in parameter adjustment, and automatic parameter adjustment is realized with unified standards.

[0018] Furthermore, in step S1, real-time injection molding data is collected, including data in the mold, and also includes collecting process parameters of the injection molding machine, and the process parameters of the injection molding machine are matched with the real-time cavity pressure curve data.

[0019] Since the injection molding product is injected into the mold by the injection molding machine, and the injection molding machine performs injection under the set injection molding process parameters, the current real-time cavity pressure curve data formed by the injection into the mold corresponds to the current process parameters of the injection molding machine. In order to correctly and accurately adjust the injection molding process parameters, the real-time injection molding data that needs to be collected includes the data collected in the mold and the process parameters of the injection molding machine, and the process parameters of the injection molding machine must correspond to the real-time cavity pressure curve data.

[0020] Furthermore, if the mold intelligent terminal wants to compare the real-time cavity pressure curve with the standard cavity pressure curve, it needs to obtain the standard cavity pressure curve first. The standard cavity pressure curve is determined before the mold leaves the factory.

[0021] The standard cavity pressure curve in step S2 is obtained by performing multiple injection molding tests before the mold leaves the factory, recording the cavity pressure curve of each test, and evaluating the quality of the finished product. When the product quality is qualified, the corresponding cavity pressure curve is determined as the standard curve.

[0022] Furthermore, in step S2, by comparing the values ​​of characteristic points of the time when the sensor in the mold contacts the melt, the filling time, the peak pressure, the peak time, the rate of decrease of the cavity pressure curve after holding pressure, or the time when the slope of the second half of the cavity pressure curve changes significantly, a quantitative representation of the difference between the real-time cavity pressure curve and the standard cavity pressure curve is obtained.

[0023] When the method of comparing feature points is adopted, one or at least one feature point is compared.

[0024] Furthermore, in step S3, the mold intelligent terminal automatically adjusts the injection molding process parameters. By quantitatively representing the curve differences, the mold intelligent terminal automatically analyzes the injection molding process parameters that need to be adjusted, combines the injection molding process parameters corresponding to the current real-time cavity pressure curve, and appropriately adjusts the process that needs to be adjusted to generate a new set of injection molding process parameters.

[0025] Furthermore, it is determined whether the injection speed needs to be adjusted based on the comparison of the time when the sensor in the mold contacts the melt, the mold filling time or the peak time;

[0026] Alternatively, when holding pressure is set based on a set time after the start of injection, it is determined whether the injection speed needs to be adjusted based on the peak pressure comparison.

[0027] Furthermore, it is determined whether the injection pressure needs to be adjusted based on the peak pressure comparison.

[0028] Furthermore, according to the comparison of the decreasing speed of the cavity pressure curve after holding pressure, it is judged whether the holding time or holding speed needs to be adjusted;

[0029] Determine whether the mold temperature needs to be adjusted based on the drop rate of the cavity pressure curve after pressure holding;

[0030] By comparing the time when the slope of the second half of the cavity pressure curve changes significantly, it can be determined whether the pressure holding end time needs to be adjusted.

[0031] After adopting the above technical scheme, the present invention has the following beneficial effects compared with the prior art.

[0032] The invention discloses a closed-loop parameter adjustment method for an injection molding process, comprising the following steps: S1, collecting real-time injection molding data to form a real-time cavity pressure curve; S2, a mold intelligent terminal compares the real-time cavity pressure curve with a standard cavity pressure curve, and adopts a method of comparing characteristic points, by comparing the values ​​of characteristic points at the time when the sensor in the mold contacts the melt, the filling time, the peak pressure, the peak time, the cavity pressure curve decrease speed after holding pressure, or the moment when the slope of the second half of the cavity pressure curve changes significantly, the difference between the two is calculated and a judgment is made: if the difference is within a preset range, the injection molding is continued according to the current injection molding process parameters; if the difference is not within the preset range, step S3 is executed; S3, the mold intelligent terminal automatically adjusts the injection molding process parameters according to the difference and the injection molding process parameters corresponding to the current real-time cavity pressure curve, and inputs them into the injection molding machine, and the injection molding machine performs injection molding again; S4, steps S1-S3 are repeated until the difference between the real-time cavity pressure curve and the standard cavity pressure curve is within the preset range, thereby forming a closed-loop control. The mold intelligent terminal compares the real-time cavity pressure curve with the standard cavity pressure curve, calculates the difference between the two and makes a judgment to determine whether the injection molded product is qualified and whether the injection molding process parameters need to be adjusted. If no adjustment is needed, the production continues or if adjustment is needed, the injection molding process parameters are automatically adjusted and the adjusted injection molding process parameters are input into the injection molding machine for execution, and then a new round of steps such as collecting real-time injection molding data are performed again. The present invention digitizes the injection molding process, and the mold intelligent terminal can realize closed-loop control, does not require manual intervention to adjust parameters, reduces dependence on manual experience, and is more standardized.

[0033] The specific implementation modes of the present invention are further described in detail below in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The accompanying drawings are part of the present invention and are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention, but do not constitute an improper limitation of the present invention. Obviously, the drawings described below are only some embodiments. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work. In the accompanying drawings:

[0035] Figure 1 It is a schematic diagram of a closed-loop parameter adjustment method for an injection molding process of the present invention.

[0036] Figure 2 It is a schematic diagram of the cavity pressure change in the present invention.

[0037] It should be noted that these drawings and textual descriptions are not intended to limit the conceptual scope of the present invention in any way, but are intended to illustrate the concept of the present invention for those skilled in the art by referring to specific embodiments. DETAILED DESCRIPTION

[0038] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. The following embodiments are used to illustrate the present invention but are not used to limit the scope of the present invention.

[0039] In the description of the present invention, it should be noted that the terms "upper", "lower", "front", "back", "left", "right", "vertical", "inside", "outside", etc. indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings. They are only used to facilitate the description of the present invention and simplify the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, they cannot be understood as limitations on the present invention.

[0040] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0041] The present invention provides an injection molding system, which includes a mold intelligent terminal, a mold, and an injection molding machine. The mold intelligent terminal is electrically connected to a pressure sensor installed in the mold and communicates with the injection molding machine.

[0042] The mold intelligent terminal is provided with a computing device with edge computing capabilities and an onboard display input device.

[0043] The onboard display input device provided in the mold intelligent terminal is, in this embodiment, an industrial LCD screen fixedly installed on the mold intelligent terminal, which is touch-operated, suitable for extreme environments, stable in operation, and has a long service life. It is used to display real-time curves; query and compare historical curves; display and modify parameters. Its operation menu includes: real-time display: display real-time pressure curves, characteristic point analysis results display, and qualified marks; parameter setting: used to configure acquisition parameters, monitoring strategies, and output signals; data management: can query historical curves, compare multiple curves, view trend charts, and export data; process tuning: first trial process calculation, tuning start button, display process parameters, display tuning suggestions, process write button; equipment management: equipment information display, equipment upgrade button, etc. Its operation interface is written in Qt.

[0044] The airborne display input device has good transmission stability and timeliness, is easy to use, and can be assembled according to the required configuration, which can save configuration and avoid waste.

[0045] The mold intelligent terminal has edge computing capabilities and can analyze the collected data, such as comparing different curves and analyzing curve feature points. It can optimize the injection molding process based on the collected data; it can monitor the pressure data according to the configured monitoring strategy, etc.

[0046] The mold intelligent terminal has local data storage, which can store no less than one week's data locally and supports USB data export.

[0047] The injection molding system also includes a production line robot arm, which is connected to the mold intelligent terminal for communication and control. The production line robot arm is installed next to the mold. When the mold intelligent terminal monitors the real-time cavity pressure curve to be abnormal, it controls the production line robot arm to sort unqualified injection molding products to the designated area for manual quality inspection.

[0048] In this embodiment, the injection molding system also includes a server, which communicates with the mold intelligent terminal. The mold intelligent terminal has a network port communication, is connected to the factory local area network, and is in the same local area network as the background server and the injection molding machine, and is used to transmit data to the background, query historical data from the background, and interact with the injection molding machine.

[0049] The mold intelligent terminal communicates with the injection molding machine through the local area network, the protocol is OPC, and the injection molding machine supports the OPC communication protocol. The background server runs the OPC Server, the injection molding machine is connected, and the mold intelligent terminal is an OPC Client, which obtains the injection molding process parameters of the injection molding machine from the OPC server.

[0050] The mold intelligent terminal can collect and modify the injection molding process parameters of the injection molding machine without the need for an external network. It can be connected and operated on-site, with on-site calculations at a fast speed. In addition, each mold intelligent terminal performs edge computing, and resources are dispersed, reducing server pressure.

[0051] The mold intelligent terminal has local data storage. In addition to uploading data to the background server, it can store no less than one week's data locally and supports USB data export.

[0052] Alternatively, in other embodiments, a server may not be provided, and the required server functions may be moved to the mold intelligent terminal.

[0053] The mold intelligent terminal is placed adjacent to the injection molding machine in the same workplace and communicates via a local area network.

[0054] The mold intelligent terminal is set up next to the injection molding machine in a position that is easy to view and operate, and is provided with a matching work base or connecting frame for easy use on the ground or fixed on the injection molding machine.

[0055] The mold intelligent terminal has signal input detection, which can connect some electrical signals of the injection molding machine to the mold intelligent terminal. The mold intelligent terminal can take actions based on these signals, such as the mold closing signal, which the mold intelligent terminal can use as the signal to start data collection.

[0056] According to mold flow analysis and mold characteristics, the installation position of the sensor is determined, and a pressure sensor is installed. The pressure sensor is connected to the junction box, which is fixed to the mold. The junction box is a transfer function, which is connected to the analog-to-digital conversion chip of the mold intelligent terminal through a cable. The mold intelligent terminal converts the electrical signal of the pressure sensor into a digital signal through the analog-to-digital conversion chip. The junction box has a unique identifier, and the mold intelligent terminal can adapt the pressure sensor parameters configured by the background server according to the connection with the junction box.

[0057] The mold intelligent terminal communicates with the background server through MQTT. The mold intelligent terminal uploads the collected data to the server for storage. The results of the edge computing of the mold intelligent terminal are also uploaded to the server. The server displays the data through the web. The server also manages mold information, such as the sensor signal, installation location, sensor parameters, etc. installed on the mold. The mold intelligent terminal pulls all parameter information corresponding to the mold from the server.

[0058] The mold intelligent terminal can perform edge computing: When collecting data, the mold intelligent terminal will calculate the characteristic values ​​of the cavity pressure curve in real time as needed, such as the time point when the pressure starts to rise, the peak pressure and the peak time.

[0059] When collecting data, the mold intelligent terminal will monitor the cavity pressure curve data according to the configured monitoring strategy, and generate an alarm message when the data value exceeds the range. The monitoring strategies supported by the mold intelligent terminal include: area monitoring - the pressure cannot exceed the specified range within the specified time interval; peak monitoring - the peak value of the cavity pressure curve cannot exceed the specified range; peak time - the time when the peak value of the cavity pressure curve reaches the specified range; peak integral monitoring - the peak integral of the cavity pressure curve cannot exceed the specified range; curve integral monitoring - the full integral of the cavity pressure curve cannot exceed the specified range; curve range monitoring - specify two complete cavity pressure curves, and the real-time cavity pressure curve must be within the two specified cavity pressure curve intervals, etc.

[0060] The mold intelligent terminal can analyze the production line situation: the mold intelligent terminal can analyze the abnormal situation of the production line through the feature point set of historical data within a self-defined time range. For example, if the cycle of the cavity pressure curve changes, the occasional situation may be caused by equipment abnormality, and the equipment needs to be tested. If the cavity pressure curve reaches a new stable state after the cycle changes, it may be that the process parameters have been adjusted; for example, if the interval time of the cavity pressure curve changes, it means that a shutdown has occurred and needs to be checked.

[0061] The mold intelligent terminal can perform first-trial process calculations: key information such as injection molding machine model, injection molding material, mold type, product wall thickness, etc. is input through the mold intelligent terminal's onboard display input device screen. The mold intelligent terminal will calculate the first-trial process parameters. Based on the first-trial process parameters and combined with the process optimization function, the mold trial can be completed quickly.

[0062] Process tuning of mold intelligent terminal: The mold intelligent terminal has a built-in process tuning expert system algorithm. According to the real-time cavity pressure curve data collected by the current injection molding process, it is compared with the expected standard cavity pressure curve. In combination with the expert system algorithm, the injection molding process parameters are adjusted and output to the screen of the onboard display input device for injection molding process parameter display. The adjusted injection molding process parameters are highlighted. After the new injection molding process parameters are executed, the real-time cavity pressure curve collected is compared with the standard cavity pressure curve again to determine whether it needs to be tuned again, until the real-time cavity pressure curve and the standard cavity pressure curve meet the expected degree of fit.

[0063] The mold intelligent terminal can perform historical records and trend statistics: the mold intelligent terminal uploads the results of edge computing to the server for storage. Through time tags, the mold intelligent terminal can obtain historical curve records from the server.

[0064] If a time tag range is selected, the set of characteristic points of all cavity pressure curve records within this range can be retrieved from the server to form a characteristic trend graph, such as a peak trend graph, a production cycle trend graph, a cycle interval trend graph, etc. Combined with the data of this characteristic point, the stability of the production line, whether there is downtime, whether there is process adjustment, etc. can be analyzed.

[0065] like Figure 1 As shown, the present invention proposes a closed-loop parameter adjustment method for an injection molding process, comprising the following steps:

[0066] S1. The mold intelligent terminal collects real-time injection molding data to form a real-time cavity pressure curve;

[0067] S2. The mold intelligent terminal compares the real-time cavity pressure curve with the standard cavity pressure curve, calculates the difference between the two and makes a judgment:

[0068] If the difference is within the preset range, the injection molding will continue according to the current injection molding process parameters;

[0069] If the difference is not within the preset range, execute step S3;

[0070] S3. The mold intelligent terminal automatically adjusts the injection molding process parameters according to the difference and the injection molding process parameters corresponding to the current real-time cavity pressure curve and inputs them into the injection molding machine, and the injection molding machine performs injection molding again;

[0071] S4, repeating steps S1-S3 until the difference between the real-time cavity pressure curve and the standard cavity pressure curve is within a preset range, thereby forming a closed-loop control.

[0072] By collecting real-time injection data during each injection to form a real-time cavity pressure curve and comparing it with the standard cavity pressure curve, it can be determined whether the difference between the two pressure curves is within a preset range.

[0073] If the difference is not within the preset range, it means that the injection molded product formed by this injection molding is unqualified, and the injection molding process parameters need to be adjusted and the injection molding is carried out using the adjusted injection molding process parameters until the comparison difference between the real-time cavity pressure curve after the injection molding process parameters are adjusted and the standard cavity pressure curve is within the preset range. The injection molding machine continues to produce under the injection molding process parameters corresponding to the current real-time cavity pressure curve.

[0074] If the difference is within the preset range, it means that the injection molded product formed by this injection molding is qualified, the current injection molding process parameters are reasonable, and production can continue under the current injection molding process parameters.

[0075] The injection molding process parameters are adjusted by the mold intelligent terminal based on the difference between the current real-time cavity pressure curve and the standard cavity pressure curve and the injection molding process parameters corresponding to the current real-time cavity pressure curve. The mold intelligent terminal automatically adjusts the injection molding process parameters and inputs them into the injection molding machine.

[0076] The mold intelligent terminal automatically collects real-time injection molding data to form a real-time cavity pressure curve, compares the real-time cavity pressure curve with the standard cavity pressure curve, and determines whether the injection molding process parameters need to be adjusted and how to adjust the injection molding process parameters based on the comparison results, and inputs the adjusted injection molding process parameters into the injection molding machine. When the injection molding machine adopts the adjusted injection molding process parameters for injection molding, real-time injection molding data is collected to form a real-time cavity pressure curve. A new round of steps are all automatically completed by the mold intelligent terminal, which can realize closed-loop control and completely complete the execution and adjustment of the injection molding work until continuous production is met. There is no need for manual intervention in parameter adjustment, and automatic parameter adjustment is realized with unified standards.

[0077] During the first injection molding, a closed-loop parameter adjustment method for the injection molding process is provided, wherein step S0 is provided before step S1.

[0078] S0. Input the key information of injection molding machine model, injection molding material, mold type, and product wall thickness through the onboard display input device screen of the mold intelligent terminal. The mold intelligent terminal performs the first trial process calculation, calculates the first trial injection molding process parameters and inputs them into the injection molding machine. Based on the first trial injection molding process parameters, the injection molding machine performs injection molding. Based on the first trial injection molding process parameters and combined with the process optimization function of the mold intelligent terminal, the mold trial can be completed quickly.

[0079] In other embodiments, in order to ensure safety during mold closing, the calculated first trial injection molding process parameters are displayed through the onboard display input device of the mold intelligent terminal, and are automatically input into the injection molding machine after confirmation by the operator, and the injection molding machine performs injection molding.

[0080] The process tuning of the mold intelligent terminal is carried out through the following methods: the mold intelligent terminal has a built-in process tuning expert system algorithm, and compares the real-time cavity pressure curve data collected by the current injection molding process with the expected standard cavity pressure curve. In combination with the expert system algorithm, the injection molding process parameters are adjusted and output to the screen of the onboard display input device for injection molding process parameter display, highlighting the adjusted injection molding process parameters. The mold intelligent terminal inputs the new injection molding process parameters into the injection molding machine. After the injection molding machine executes the new injection molding process parameters, the mold intelligent terminal compares the collected real-time cavity pressure curve with the standard cavity pressure curve again to determine whether it needs to be tuned again until the real-time cavity pressure curve and the standard cavity pressure curve meet the expected degree of fit.

[0081] In step S1, real-time injection molding data is collected, including data in the mold, and also includes collecting process parameters of the injection molding machine, and the process parameters of the injection molding machine are matched with real-time cavity pressure curve data.

[0082] Since the injection molding product is injected into the mold by the injection molding machine, and the injection molding machine performs injection under the set injection molding process parameters, the current real-time cavity pressure curve data formed by the injection into the mold corresponds to the current process parameters of the injection molding machine. In order to correctly and accurately adjust the injection molding process parameters, the real-time injection molding data that needs to be collected includes the data collected in the mold and the process parameters of the injection molding machine, and the process parameters of the injection molding machine must correspond to the real-time cavity pressure curve data.

[0083] In step S2, the mold intelligent terminal needs to compare the real-time cavity pressure curve with the standard cavity pressure curve, and needs to first obtain the standard cavity pressure curve. The standard cavity pressure curve is determined before the mold leaves the factory and can be pre-stored in the mold intelligent terminal.

[0084] The standard cavity pressure curve in step S2 is obtained by performing multiple injection molding tests before the mold leaves the factory. The cavity pressure curve of each test is recorded and the quality of the finished product is evaluated. When the product quality is qualified, the corresponding cavity pressure curve is determined as the standard curve and bound to the mold code as the basis for subsequent quality judgment of the mold.

[0085] In step S2, a method of comparing characteristic points is adopted to compare the values ​​of the characteristic points of the cavity pressure curve to obtain a quantitative representation of the difference between the real-time cavity pressure curve and the standard cavity pressure curve.

[0086] The characteristic points include the time when the sensor in the mold contacts the melt, the filling time, the peak pressure, the peak time, the decreasing speed of the cavity pressure curve after holding pressure, and the moment when the slope of the second half of the cavity pressure curve changes significantly.

[0087] When the method of comparing feature points is adopted, at least one of the feature points is compared.

[0088] In this embodiment, a solution of comparing one feature point is adopted.

[0089] The mold intelligent terminal collects real-time injection pressure data sensed by the pressure sensor inside the mold during each injection to form a real-time cavity pressure curve. By comparing it with the standard cavity pressure curve, it can determine whether the difference between the two pressure curves is within the preset range.

[0090] If the difference is not within the preset range, it means that the injection molded product formed by this injection molding is unqualified. It is necessary to use a robotic arm to sort the unqualified products to the designated area, and it is necessary to adjust the injection molding process parameters and use the adjusted injection molding process parameters for injection molding until the comparison difference between the real-time cavity pressure curve after adjusting the injection molding process parameters and the standard cavity pressure curve is within the preset range. The injection molding machine continues to produce under the injection molding process parameters corresponding to the current real-time cavity pressure curve.

[0091] If the difference is within the preset range, it means that the injection molded product formed by this injection molding is qualified, the current injection molding process parameters are reasonable, and production can continue under the current injection molding process parameters.

[0092] The difference is within the preset range, which means that the real-time cavity pressure curve and the standard cavity pressure curve do not match but the difference is small. This difference is within the preset difference range and is acceptable, so the injection molded product is still considered qualified; or, the difference is within the preset range, which means that the real-time cavity pressure curve and the standard cavity pressure curve match, and the difference is zero.

[0093] The injection molding process parameters are adjusted by the mold intelligent terminal based on the difference between the current real-time cavity pressure curve and the standard cavity pressure curve and the injection molding process parameters corresponding to the current real-time cavity pressure curve. The mold intelligent terminal automatically adjusts the injection molding process parameters and displays them through the onboard display input device, and automatically inputs them into the injection molding machine.

[0094] The mold intelligent terminal automatically collects real-time injection molding data to form a real-time cavity pressure curve, compares the real-time cavity pressure curve with the standard cavity pressure curve, and determines whether the injection molding process parameters need to be adjusted and how to adjust the injection molding process parameters based on the comparison results, and inputs the adjusted injection molding process parameters into the injection molding machine. When the injection molding machine adopts the adjusted injection molding process parameters for injection molding, real-time injection molding data is collected again to form a real-time cavity pressure curve. A new round of steps can be performed to achieve closed-loop control, completely complete the execution and adjustment of the injection molding work until continuous production is met, and realize automatic parameter adjustment with unified standards.

[0095] In step S3, the mold intelligent terminal automatically adjusts the injection molding process parameters. Based on the quantitative representation of the curve difference, the mold intelligent terminal automatically analyzes the injection molding process parameters that need to be adjusted, combines the injection molding process parameters corresponding to the current real-time cavity pressure curve, and appropriately adjusts the process that needs to be adjusted to generate a new set of injection molding process parameters.

[0096] When adjusting the injection molding process parameters by comparing the values ​​of the characteristic points, the strategy is as follows:

[0097] 1. The contact time of the sensor in the mold with the melt. During injection molding, the material is injected from the injection barrel into the mold. The faster the material injection speed, the shorter the contact time of the sensor in the mold with the melt. The relationship can be approximately understood as linear, and the formula is: Among them, t0 is the time from mold closing to injection start, v is the injection speed, and x is the change in the material position in the injection barrel. Since the shape of the injection barrel is fixed, the injection time can be determined by the ratio of the change in the material position in the injection barrel during each injection to the injection speed, so the time from mold closing to the time when the sensor in the mold contacts the melt can be determined. By comparing the characteristic points of the time when the sensor in the mold contacts the melt, it can be determined whether the injection speed needs to be adjusted.

[0098] 2. Mold filling time refers to the time it takes for the melt to fill the mold cavity. The faster the injection speed, the shorter the mold filling time. Figure 2 As shown in the figure, the pressure starts to rise after the melt enters the mold cavity, and the pressure rises rapidly after the cavity is filled, which is manifested as a larger slope of the cavity pressure curve. The change in the slope of the cavity pressure curve after the melt contacts the pressure sensor can determine the filling time. By comparing the characteristic points of the filling time, it can be determined whether the injection speed needs to be adjusted.

[0099] 3. After the cavity is filled, the melt continues to enter the cavity of the mold, the pressure rises rapidly, reaches the maximum value (peak value), and then switches to pressure holding, that is, from the injection state to the pressure holding state. The peak value is related to the injection pressure. The higher the injection pressure, the greater the peak value. According to the comparison of the peak pressure characteristic points, it can be judged whether the injection pressure needs to be adjusted.

[0100] 4. Peak time is related to injection speed. The greater the injection pressure, the greater the peak value. However, peak time is not necessarily fast or slow. It depends on the injection speed. The faster the injection speed, the smaller the peak time. By comparing the characteristic points of peak time, it can be judged whether the injection speed needs to be adjusted.

[0101] 5. If the pressure holding is based on time, that is, the pressure holding is set based on the set time after the start of injection, for example, the pressure holding is started 5 minutes after the start of injection, then the injection speed may also affect the peak value. For example, if the injection speed is very slow and the melt material has not completely entered the mold cavity before the pressure holding is started, the peak pressure may be smaller than expected because the pressure holding is started before the peak value is actually reached. When the pressure holding is set based on a certain time, the injection speed can be judged based on the comparison of the peak pressure characteristic points.

[0102] 6. The holding pressure is generally lower than the injection pressure. After the holding pressure is switched, the cavity pressure curve begins to drop. If the curve drops quickly and forms a peak, it is because the holding time is too short, the gate is not sealed, and material reflux may occur. By comparing the characteristic points of the cavity pressure curve drop speed after holding pressure, it can be determined whether the holding time or holding speed needs to be adjusted.

[0103] 7. Under normal circumstances, the speed at which the cavity pressure curve drops after holding pressure depends on the cooling speed of the product, which is related to the temperature of the mold. By comparing the characteristic points of the speed at which the cavity pressure curve drops after holding pressure, it can be determined whether the mold temperature needs to be adjusted.

[0104] 8. In the second half of the cavity pressure curve, the moment when the slope changes significantly indicates that the gate is frozen and sealed, and it is most appropriate to end the pressure holding at this time. By comparing the characteristic points at the moment when the slope of the second half of the cavity pressure curve changes significantly, it can be determined whether it is necessary to consider adjusting the end time of the pressure holding.

[0105] The present invention uses a quantifiable curve to replace manual judgment of product quality, which is more scientific and accurate; the mold intelligent terminal automatically calculates the difference between the actual curve and the standard curve, and then adjusts the parameters through a specific parameter adjustment algorithm model, replacing the existing manual parameter adjustment. Through automated closed-loop control, human intervention is reduced and parameter adjustment efficiency is improved; based on real-time feedback of the cavity pressure curve, accurate process parameter adjustment is achieved, and accuracy is improved; the influence of human factors is reduced, the consistency of product quality is improved, and errors are reduced; a systematic closed-loop control mechanism is formed to facilitate process optimization and management, and can achieve systematic management.

[0106] The present invention discloses a closed-loop parameter adjustment method for injection molding process, comprising the following steps: S1, collecting real-time injection molding data to form a real-time cavity pressure curve; S2, the mold intelligent terminal compares the real-time cavity pressure curve with the standard cavity pressure curve, calculates the difference between the two and makes a judgment: if the difference is within the preset range, the injection molding is continued according to the current injection molding process parameters; if the difference is not within the preset range, step S3 is executed; S3, the mold intelligent terminal automatically adjusts the injection molding process parameters according to the difference and the injection molding process parameters corresponding to the current real-time cavity pressure curve and inputs them into the injection molding machine, and the injection molding machine performs injection molding again; S4, repeating steps S1-S3 until the difference between the real-time cavity pressure curve and the standard cavity pressure curve is within the preset range, forming a closed-loop control. The mold intelligent terminal compares the real-time cavity pressure curve with the standard cavity pressure curve, calculates the difference between the two and makes a judgment to determine whether the injection molding product is qualified and whether the injection molding process parameters need to be adjusted, and continues to produce when no adjustment is required or automatically adjusts when adjustment is required and inputs the adjusted injection molding process parameters into the injection molding machine for execution, and then performs a new round of steps such as collecting real-time injection molding data again. The mold intelligent terminal can achieve closed-loop control, without the need for human intervention to adjust parameters, and can achieve automatic parameter adjustment with unified standards.

[0107] The above description is only a preferred embodiment of the present invention, and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technician familiar with this patent can make some changes or modifications to equivalent embodiments of equivalent changes by using the technical content suggested above without departing from the scope of the technical solution of the present invention. The implementation scheme in the above embodiment can also be further combined or replaced. However, any simple modification, equivalent change and modification made to the above embodiment based on the technical essence of the present invention without departing from the content of the technical solution of the present invention still falls within the scope of the solution of the present invention.

Claims

1. A closed-loop parameter adjustment method for an injection molding process, characterized in that: The following steps are involved: S1. The mold intelligent terminal collects real-time injection molding data to form a real-time cavity pressure curve; S2. The mold intelligent terminal compares the real-time cavity pressure curve and the standard cavity pressure curve, and adopts the method of comparing characteristic points. By comparing the values ​​of the characteristic points of the cavity pressure curve, the difference between the two is calculated and judged: If the difference is within the preset range, the injection molding will continue according to the current injection molding process parameters; If the difference is not within the preset range, execute step S3; S3. The mold intelligent terminal automatically adjusts the injection molding process parameters according to the difference and the injection molding process parameters corresponding to the current real-time cavity pressure curve and inputs them into the injection molding machine, and the injection molding machine performs injection molding again; S4, repeating steps S1-S3 until the difference between the real-time cavity pressure curve and the standard cavity pressure curve is within a preset range, thereby forming a closed-loop control.

2. The closed-loop parameter adjustment method for injection molding process according to claim 1, characterized in that: In step S1, real-time injection molding data is collected, including data in the mold, and also includes collecting process parameters of the injection molding machine, and the process parameters of the injection molding machine are matched with real-time cavity pressure curve data.

3. The closed-loop parameter adjustment method for injection molding process according to claim 1, characterized in that: The standard cavity pressure curve in step S2 is determined based on the cavity pressure curve corresponding to the qualified product before the mold leaves the factory.

4. The closed-loop parameter adjustment method for injection molding process according to claim 1, characterized in that: In step S2, by comparing the values ​​of the characteristic points of the time when the sensor in the mold contacts the melt, the filling time, the peak pressure, the peak time, the decreasing speed of the cavity pressure curve after holding pressure, or the time when the slope of the second half of the cavity pressure curve changes significantly, a quantitative representation of the difference between the real-time cavity pressure curve and the standard cavity pressure curve is obtained.

5. The closed-loop parameter adjustment method for injection molding process according to claim 4, characterized in that: When the method of comparing feature points is adopted, at least one of the feature points is compared.

6. The closed-loop parameter adjustment method for injection molding process according to claim 4, characterized in that: In step S3, the mold intelligent terminal automatically adjusts the injection molding process parameters. Based on the quantitative representation of the curve difference, the mold intelligent terminal automatically analyzes the injection molding process parameters that need to be adjusted, combines the injection molding process parameters corresponding to the current real-time cavity pressure curve, and appropriately adjusts the process that needs to be adjusted to generate a new set of injection molding process parameters.

7. The closed-loop parameter adjustment method for injection molding process according to claim 5, characterized in that: Determine whether the injection speed needs to be adjusted based on the time the sensor in the mold contacts the melt, the filling time or the peak time. Alternatively, when holding pressure is set based on a set time after the start of injection, it is determined whether the injection speed needs to be adjusted based on the peak pressure comparison.

8. The closed-loop parameter adjustment method for injection molding process according to claim 5, characterized in that: Determine whether the injection pressure needs to be adjusted based on the peak pressure comparison.

9. The closed-loop parameter adjustment method for injection molding process according to claim 5, characterized in that: According to the comparison of the decreasing speed of the cavity pressure curve after pressure holding, determine whether it is necessary to adjust the pressure holding time or pressure holding speed; Determine whether the mold temperature needs to be adjusted based on the comparison of the decreasing speed of the cavity pressure curve after pressure holding.

10. The closed-loop parameter adjustment method for injection molding process according to claim 5, characterized in that: By comparing the time when the slope of the second half of the cavity pressure curve changes significantly, it can be determined whether the pressure holding end time needs to be adjusted.

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