A VP switching control method for all-electric injection molding machines based on instantaneous speed control mode

Abstract

The present application relates to a VP switching control method for an all-electric injection molding machine based on an instantaneous control mode, comprising the following steps: implementing a size priority mode when the screw reaches the injection stage, obtaining the screw movement speed in real time, and performing interval control on the screw movement speed; entering an automatic deceleration mode when the screw moves to the automatic deceleration position, and maintaining the screw movement speed at a preset VP switching position until the screw movement speed reaches zero; entering an instantaneous control mode after the screw passes the preset VP switching position, obtaining a preset instantaneous time and a preset instantaneous speed, and controlling the screw according to the preset instantaneous time and preset instantaneous speed; monitoring the injection pressure of the screw in the instantaneous control mode; obtaining the screw's instantaneous movement time, and when the screw's instantaneous movement time coincides with the preset instantaneous time, performing a VP switching on the screw and entering a pressure holding stage. The present application has the effect of providing a buffer during the process of the screw switching from speed control to pressure control.

Description

Technical Field

[0001] The present application relates to the technical field of electric injection molding machines, and in particular to a VP switching control method for an all-electric injection molding machine based on an instantaneous speed control mode. Background Art

[0002] An electric injection molding machine is a fully electric horizontal injection molding machine. It is the primary molding equipment for producing various plastic parts from thermoplastics or thermosetting plastics. It utilizes AC servo motors, ball screws, toothed pulleys, and other components to drive the various mechanisms within the machine. All mechanisms within the machine are electrically driven. Each mechanism, including those involved in the injection and mold closing processes, is driven by servo motors.

[0003] The working process of an injection molding machine is as follows: powdered or granular plastic is fed from the injection molding machine's hopper into a heated barrel. It is heated and melted to a molten state. The screw then pushes the molten plastic from the nozzle at the front of the barrel into the mold cavity. The mold cavity temperature is relatively low, and upon encountering the heated plastic, it cools and solidifies into a plastic product. During the injection molding process, the screw speed must be controlled to allow a large amount of plastic to be filled into the mold cavity. When the mold cavity is almost full of plastic, the screw speed control must be switched to pressure control to accommodate the cooling and shrinkage of the plastic injected into the mold cavity. This allows the screw to pressurize the remaining plastic into the voids within the mold cavity, thus forming the product. The switchover point between screw speed control and pressure control corresponds to a switching point. This switching point is called the VP switching point, also known as the speed and pressure switching point.

[0004] In the related art, the injection speed and pressure switching control method of the electric injection molding machine is to increase the pressure of the screw when the screw moves to the speed and pressure switching point so that the movement of the screw can be smoothly switched from speed control to pressure control.

[0005] However, switching the screw from speed control to pressure control takes only a split second. If the screw speed is instantly reduced to zero and the screw pressure is increased to allow the screw to complete the speed and pressure switch, the screw injection work will have no chance to buffer, which may affect the injection molding effect and cause product defects. Summary of the Invention

[0006] In order to improve the phenomenon of no buffer between screw speed and pressure switching in the related art, the present application provides a VP switching control method for an all-electric injection molding machine based on an instantaneous control mode.

[0007] The present application provides a VP switching control method for an all-electric injection molding machine based on an instantaneous speed control mode, which adopts the following technical solutions:

[0008] A VP switching control method for an all-electric injection molding machine based on an instantaneous speed control mode comprises the following steps:

[0009] When the screw enters the injection stage, the screw implements the size priority mode, obtains the screw movement speed in real time, and performs interval control on the screw movement speed before the screw reaches the preset VP switching position;

[0010] When the screw moves to the automatic deceleration position, it enters the automatic deceleration mode until the screw movement speed reaches zero when it reaches the preset VP switching position;

[0011] After the screw passes the preset VP switching position, it enters the instantaneous speed control mode, obtains the preset instantaneous speed time and the preset instantaneous speed, and controls the screw according to the preset instantaneous speed time and the preset instantaneous speed. The instantaneous speed control mode includes a time control mode, an automatic pressure maintaining tracking mode, and a pressure rise monitoring mode;

[0012] Monitor the injection pressure of the screw that enters the instantaneous speed control mode, obtain the instantaneous speed pressure of the screw in real time, and compare it with the preset VP switching pressure monitoring value to determine whether the instantaneous speed pressure of the screw is normal;

[0013] The instantaneous speed movement time of the screw is obtained. When the instantaneous speed movement time of the screw is consistent with the preset instantaneous speed time, the screw is VP-switched and enters the pressure holding stage.

[0014] By adopting the above technical solution, when the screw enters the injection stage, the size priority mode is implemented for the screw. At this time, the screw movement speed is obtained in real time. The screw movement speed is interval-controlled before the screw reaches the preset VP switching position. The screw movement speed is controlled within this interval until the screw moves to the automatic deceleration position and enters the automatic deceleration mode, so that the screw movement speed is zero when it reaches the preset VP position. Then, the system enters the instantaneous control mode. The system obtains the preset instantaneous time and preset instantaneous speed, controls the screw according to the preset instantaneous speed, and monitors the injection pressure of the screw entering the instantaneous control mode. The screw instantaneous pressure is obtained and compared with the preset VP switching pressure monitoring value to determine whether the screw instantaneous pressure at this time is normal, so that the screw instantaneous pressure is kept within the normal range until the screw instantaneous movement time is consistent with the preset instantaneous time, at which time the screw is VP-switched and enters the pressure holding stage. By setting the instantaneous speed control mode to control the screw, the screw is buffered during the process of switching from speed control to pressure control, so that the screw can better enter the pressure holding stage and ensure the quality of injection molding.

[0015] Furthermore, the size priority mode means that the screw decelerates in advance before reaching the preset VP switching position and stops at the preset VP switching position.

[0016] By adopting the above technical solution, the size priority mode enables the screw to decelerate in advance when it reaches the preset VP switching position, so that the speed of the screw is zero when it reaches the preset VP switching position, and it is convenient to control the speed of the screw after entering the instantaneous speed control mode.

[0017] Furthermore, the preset instantaneous speed time can be set in a range of 10ms-3000ms, and the setting method of the preset instantaneous speed time includes the following three methods:

[0018] Turn off the system's automatic time calculation function and enter the preset instantaneous speed time in the system before screw injection;

[0019] Turn on the automatic time calculation function of the system. When the screw enters the instantaneous speed control mode, obtain the total injection time of the screw and the screw speed control running time, and subtract the two to obtain the preset instantaneous speed time;

[0020] Using standard fixed time, multiple modes are set in the system with a time range of 10ms-3000ms. The system automatically executes according to the requirements of multiple modes.

[0021] By adopting the above technical solution, the range of the preset instantaneous time is between 10ms and 3000ms, and there are three methods for setting the preset instantaneous time, which can be selected according to actual conditions. The preset instantaneous time can be manually entered, the system automatically sets the preset instantaneous time, and a standard fixed time can be used as the preset instantaneous time.

[0022] Furthermore, the preset instantaneous speed is the running speed of the screw after entering the instantaneous speed control mode.

[0023] By adopting the above technical solution, the preset instantaneous speed is the running speed of the screw after entering the instantaneous speed control mode. The preset instantaneous speed is set for the screw after entering the instantaneous speed control mode, so that the screw can always maintain the same speed.

[0024] Furthermore, the instantaneous screw pressure is obtained in real time and compared with a preset VP switching pressure monitoring value to determine whether the instantaneous screw pressure is normal, including the following steps:

[0025] When the instantaneous pressure of the screw does not exceed the preset VP switching pressure monitoring value, it is judged to be normal, and the injection pressure of the screw is continuously monitored until the screw enters the holding pressure stage;

[0026] When the screw instantaneous pressure exceeds the preset VP switching pressure monitoring value, it is judged as abnormal, an alarm signal is issued, and the screw instantaneous pressure is reduced until the screw enters the pressure holding stage.

[0027] By adopting the above technical solution, the instantaneous pressure of the screw is obtained in real time and compared with the preset VP switching pressure monitoring value. When the instantaneous pressure of the screw does not exceed the preset VP switching pressure monitoring value, it is judged to be normal, and the instantaneous pressure of the screw is continuously monitored until it enters the pressure holding stage; when the instantaneous pressure of the screw exceeds the preset VP switching pressure monitoring value, it is judged to be abnormal. At this time, the system issues an alarm signal and reduces the instantaneous pressure of the screw until the screw enters the pressure holding stage.

[0028] Furthermore, the time control mode is that after the screw enters the instantaneous speed control mode, only the instantaneous speed movement time of the screw is monitored, and when the instantaneous speed movement time of the screw is consistent with the preset instantaneous speed time, the pressure holding stage is automatically entered.

[0029] By adopting the above technical solution, the time control mode only monitors the instantaneous movement time of the screw after the screw enters the instantaneous speed control mode. Once the instantaneous movement time of the screw is consistent with the preset instantaneous speed time, the screw enters the pressure holding stage.

[0030] Furthermore, the automatic pressure-holding tracking mode is to start the pressure-holding tracking mode after the screw enters the instantaneous speed control mode, monitor the screw injection pressure, and obtain the first section pressure-holding pressure value in the pressure-holding stage, compare the screw injection pressure with the first section pressure-holding pressure value, judge the pressure state of the screw and perform processing.

[0031] By adopting the above technical solution, the automatic pressure-holding tracking mode is turned on after the screw enters the instantaneous speed control mode, the screw injection pressure is monitored, and the screw injection pressure is compared with the first section of the pressure-holding pressure value in the pressure-holding stage, so as to judge the pressure state of the screw and take appropriate measures, so that the screw injection pressure in the instantaneous speed control mode is kept within the normal range.

[0032] Furthermore, the step of comparing the screw injection pressure with the first-stage holding pressure value to determine the screw pressure state and perform processing includes the following steps:

[0033] When the peak value of the screw injection pressure is greater than the first stage holding pressure value, it is determined to be in a pressure reduction state, and the screw is subjected to a pressure reduction operation until the screw injection pressure reaches the first stage holding pressure value, and then the holding stage is automatically entered;

[0034] When the peak value of the screw injection pressure is less than the first-stage holding pressure value, it is determined to be in a switching state, the automatic holding pressure tracking mode of the screw is switched to the time control mode, and an alarm message is issued. When the screw instantaneous speed movement time of the screw is consistent with the preset instantaneous speed time, the holding pressure stage is automatically entered.

[0035] By adopting the above technical solution, if the screw injection pressure is higher than the first-stage holding pressure value, the screw will quickly run at the first-stage holding pressure value after entering the holding stage. Changing the pressure value in a short time may affect the screw injection, so it is necessary to reduce the screw injection pressure in the instantaneous control mode until the screw injection pressure reaches the first-stage holding pressure value and automatically enters the holding stage; if the screw injection pressure is continuously lower than the first-stage holding pressure value, it means that there is no need to control the screw injection pressure too much in the instantaneous control mode. At this time, the system will switch the automatic holding pressure tracking mode of the screw to the time control mode until the screw enters the holding stage.

[0036] Furthermore, the pressure rise monitoring mode is to start the pressure rise monitoring mode after the screw enters the instantaneous control mode, and obtain the injection pressure of the screw in real time. If it is detected that the injection pressure of the screw is gradually increasing, the pressure holding stage is immediately entered.

[0037] By adopting the above technical solution, in pressure rise monitoring mode, the screw injection pressure is acquired in real time. If the screw injection pressure shows a gradual upward trend, it indicates that the screw injection pressure is continuously increasing. To avoid the screw having to quickly reach the required pressure value after entering the pressure holding stage, the system immediately enters the pressure holding stage when it detects a gradual upward trend in the screw injection pressure.

[0038] Furthermore, when the screw enters the instantaneous speed control mode, the time control mode, the automatic pressure holding tracking mode and the pressure rise monitoring mode are all turned on, if the screw meets the conditions of any mode in the instantaneous speed control mode, it switches to the pressure holding stage.

[0039] By adopting the above technical solution, when the screw enters the instantaneous speed control mode, the time control mode, the automatic pressure holding tracking mode and the pressure rise monitoring mode can be turned on at the same time. When the three modes are turned on at the same time, if the screw meets the conditions of any mode in the instantaneous speed control mode, it can switch to the pressure holding stage.

[0040] In summary, this application includes at least one of the following beneficial technical effects:

[0041] 1. When the screw enters the injection stage, the size priority mode is implemented for the screw. At this time, the screw movement speed is obtained in real time. The screw movement speed is controlled in intervals before the screw reaches the preset VP switching position. The screw movement speed is controlled within this interval. When the screw reaches the automatic deceleration position, the screw is decelerated until the speed reaches zero when it reaches the preset VP position. Then it enters the instantaneous control mode. The system obtains the preset instantaneous time and preset instantaneous speed, controls the screw according to the preset instantaneous speed, and monitors the injection pressure of the screw entering the instantaneous control mode until the screw instantaneous movement time is consistent with the preset instantaneous time. The screw is switched to VP and enters the pressure holding stage. By setting the instantaneous control mode to control the screw, the screw is buffered during the process of switching from speed control to pressure control, so that the screw can better enter the pressure holding stage, ensuring the quality of injection molding;

[0042] 2. By setting three instantaneous speed control modes: time control mode, automatic pressure holding tracking mode and pressure rise monitoring mode, the screw entering the instantaneous speed control mode can be flexibly controlled so that the screw is ready to smoothly enter the pressure holding stage. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 This is a flow chart of a VP switching control method for an all-electric injection molding machine based on an instantaneous control mode provided by the present application;

[0044] Figure 2 This is a flowchart of the operation of the time control mode in this application;

[0045] Figure 3 It is a timing diagram in the time control mode of this application;

[0046] Figure 4 This is a flowchart of the operation of the automatic pressure-maintaining tracking mode in this application;

[0047] Figure 5 This is the timing diagram in the automatic pressure-maintaining tracking mode of this application;

[0048] Figure 6 This is a flowchart of the operation of the pressure rise monitoring mode in this application;

[0049] Figure 7 This is a timing diagram of the pressure rise monitoring mode in this application;

[0050] Figure 8 This is a flowchart of the operation of S4 in this application. DETAILED DESCRIPTION

[0051] The following is combined with Figure 1 -Attached Figure 8 , further details of this application are given.

[0052] A VP switching control method for all-electric injection molding machines based on instantaneous control mode, referring to Figure 1 , including the following steps:

[0053] S1. When the screw enters the injection stage, the screw implements the size priority mode, obtains the screw movement speed in real time, and performs interval control on the screw movement speed before the screw reaches the preset VP switching position.

[0054] Specifically, the working process of an injection molding machine mainly includes the following stages: mold closing, injection, pressure holding, pre-molding, cooling, mold opening, and ejection. The injection and pressure holding stages are particularly important, and the screw is required in both the injection and pressure holding stages. During the injection stage, the plastic enters the barrel with a screw through a hopper. A heating device is installed outside the barrel to heat the barrel so that the plastic entering the barrel is heated to a molten state. At this time, the screw enters the injection stage, and the screw speed is controlled so that the screw drives the heated plastic into the closed mold cavity, and the plastic is filled into the mold cavity. When most of the volume in the mold cavity is filled, that is, when the plastic fills 90%-99% of the entire mold cavity volume, it is necessary to switch the screw speed control to pressure control so that the screw enters the pressure holding stage. The purpose of the holding pressure phase is that once the plastic fills the mold cavity, it solidifies upon cooling. Controlling the screw pressure pushes the remaining plastic in the barrel into the mold cavity, filling every void and completing the injection. When the injection phase switches to the holding pressure phase, a speed-pressure switching point, known as the VP switching point, is passed. After this VP switching point, the system switches from screw speed control to pressure control, allowing the screw to complete the injection process.

[0055] The timing of the system's VP switching is crucial. In this embodiment, S1 implements size-priority mode after the screw enters the injection phase, causing it to decelerate before reaching the preset VP switching position and stop there. The system determines the preset VP switching position based on the screw's injection motion and pre-configures it. Once the screw enters the injection phase, the screw's speed is acquired in real time and controlled within a range. This range is from the start of injection to the preset VP switching position. The screw's speed is the speed of the screw during injection.

[0056] After the screw movement speed is interval-controlled after entering the injection stage, the following steps are performed:

[0057] S2. When the screw moves to the automatic deceleration position, it enters the automatic deceleration mode until the screw movement speed reaches zero when it reaches the preset VP switching position.

[0058] Specifically, the screw operates in size-priority mode during the injection phase, requiring the screw to reach zero speed before reaching the preset VP switching position. An automatic deceleration position is configured within the screw speed control range. This position is pre-configured in the system and serves as a reminder to the system before the preset VP switching position. When the screw reaches the automatic deceleration position, the system senses its arrival and enters automatic deceleration mode, ensuring that the screw reaches zero speed at the preset VP switching position.

[0059] In the automatic deceleration mode, the movement speed of the screw will be greatly reduced. In the automatic deceleration mode, the fastest deceleration mode is adopted. The movement speed of the screw in the automatic deceleration mode will drop linearly, and the movement speed of the screw will be zero when it reaches the preset VP switching position.

[0060] When the screw movement speed reaches zero when it reaches the preset VP switching position, the following steps are performed:

[0061] S3. After the screw passes the preset VP switching position, it enters the instantaneous speed control mode, obtains the preset instantaneous speed time and the preset instantaneous speed, and controls the screw according to the preset instantaneous speed time and the preset instantaneous speed. The instantaneous speed control mode includes time control mode, automatic pressure holding tracking mode and pressure rise monitoring mode.

[0062] Specifically, once the screw passes the preset VP switching position, range control of the screw's speed ceases and the screw enters the next mode: instantaneous speed control. Instantaneous speed control is used between speed control and pressure control. After completing speed control, the screw is further adjusted to facilitate a smoother transition to pressure control.

[0063] In transient control mode, a preset transient time and preset transient speed are preconfigured in the system. The preset transient time refers to the time it takes for the screw to enter transient control mode. The preset transient time can be set between 10ms and 3000ms. The preset transient time is shorter, and during this time, the screw is controlled so that it reaches its optimal state within the preset transient time and enters the pressure holding phase.

[0064] Specifically, there are three methods for setting the preset instantaneous speed time:

[0065] 1. User definition: turn off the system's automatic time calculation function and enter the preset instantaneous speed time in the system before screw injection;

[0066] 2. Automatic calculation of the system: Turn on the automatic calculation time function of the system. When the screw enters the instantaneous speed control mode, obtain the total injection time of the screw and the screw speed control running time. Subtract the two to get the preset instantaneous speed time;

[0067] 3. Use standard fixed time: Set multiple modes in the system, with a time range of 10ms-3000ms, and the system automatically executes according to the requirements of multiple modes.

[0068] In the user-defined mode, the user can input the preset instantaneous speed time in the instantaneous speed control mode into the system. When the user-defined mode is selected, the automatic calculation time function of the system will be turned off, that is, the screw will be executed according to the user-defined preset instantaneous speed time when entering the instantaneous speed control mode.

[0069] In the automatic calculation mode, users do not need to configure a preset instantaneous speed time in the system. The system's automatic time calculation function is enabled. In this function, when the screw enters the instantaneous speed control mode, the system will obtain the total injection time and the screw speed control operation time. The total injection time is the time required for the screw to inject. The total injection time is configured in the system in advance and is set according to the screw's injection operation. The screw speed control operation time is the time from the screw entering the injection stage to the moment it enters the instantaneous speed control mode. The subtraction of the two is the preset instantaneous speed time.

[0070] When using the standard fixed time method, the system will set up multiple groups of modes, and the time range is between 10ms-3000ms. Each mode has different corresponding parameters. Each mode is configured in the system in advance, and the system will automatically implement according to the requirements of multiple modes.

[0071] The preset instantaneous speed is also configured in the system in advance. The preset instantaneous speed is the running speed of the screw after entering the instantaneous speed control mode. After entering the instantaneous speed control mode, the screw will run according to the preset instantaneous speed to ensure that the screw runs at a consistent speed throughout the entire process in the instantaneous speed control mode.

[0072] In this embodiment, the instantaneous speed control mode includes the time control mode, the automatic pressure maintaining tracking mode and the pressure rising monitoring mode. The parameters of each mode are different, and the requirements for the screw in the instantaneous speed control mode are also different. Figure 2 and Figure 3 , the specific steps of the time control mode are as follows:

[0073] S31, time control mode is that after the screw enters the instantaneous speed control mode, only the instantaneous speed movement time of the screw is monitored. When the instantaneous speed movement time of the screw is consistent with the preset instantaneous speed time, it automatically enters the pressure holding stage.

[0074] Specifically, the time control mode is the most basic instantaneous speed control mode. When the screw is in the instantaneous speed control mode, only the instantaneous speed of the screw is monitored. When the instantaneous speed of the screw matches the preset instantaneous speed, the screw automatically enters the pressure holding stage. The instantaneous speed of the screw refers to the time it takes for the screw to move after entering the instantaneous speed control mode. The instantaneous speed of the screw changes in real time until it matches the preset instantaneous speed. This indicates that the screw's movement time in the instantaneous speed control mode has reached the preset instantaneous speed. At this point, the screw needs to enter the pressure holding stage, and the system will automatically control the screw to enter the pressure holding stage.

[0075] The instantaneous speed control mode also includes the automatic pressure maintaining tracking mode, refer to Figure 4 and Figure 5 , the automatic pressure keeping tracking mode is as follows:

[0076] S31, automatic pressure holding tracking mode is to start the pressure holding tracking mode after the screw enters the instantaneous speed control mode, monitor the screw injection pressure, and obtain the first section pressure holding pressure value in the pressure holding stage, compare the screw injection pressure with the first section pressure holding pressure value, judge the screw pressure state and take appropriate measures.

[0077] Specifically, the automatic pressure-holding tracking mode is enabled in addition to the time-controlled mode. Once the screw enters automatic pressure-holding tracking mode, the screw injection pressure is monitored. The screw injection pressure is the pressure at which the screw operates in instantaneous speed control mode. The screw injection pressure changes in real time and requires monitoring. The system obtains the first pressure-holding pressure value during the pressure-holding phase and compares it with the injection pressure to determine the screw pressure status and take appropriate action.

[0078] After the screw passes through the transient control mode, it enters the holding phase. This phase consists of four main stages, each requiring different screw pressure values. The screw pressure is initially controlled according to the first holding pressure value. In transient control mode, the screw injection pressure is pre-controlled so that the screw reaches the first holding pressure value as soon as possible after entering the holding phase.

[0079] Compare the screw injection pressure with the first stage holding pressure value to determine the screw pressure state and take appropriate measures as follows:

[0080] S311. When the peak value of the screw injection pressure is greater than the first stage holding pressure value, it is determined to be in a pressure reduction state, and the screw is depressurized until the screw injection pressure reaches the first stage holding pressure value, and then automatically enters the pressure holding stage.

[0081] When the monitored peak screw injection pressure exceeds the first-stage holding pressure value, the system is in a pressure-reducing state. The peak screw injection pressure is the maximum value in instantaneous control mode. A pressure-reducing state indicates that the screw injection pressure is too high. If the screw injection pressure remains above the first-stage holding pressure value, the screw will quickly operate at the first-stage holding pressure value after entering the holding stage. Changing pressure values ​​in a short period of time may affect screw injection. Therefore, it is necessary to reduce the screw injection pressure in instantaneous control mode until the screw injection pressure reaches the first-stage holding pressure value, automatically entering the holding stage.

[0082] S312: When the peak value of the screw injection pressure is less than the first stage holding pressure value, it is judged to be in a switching state, and the automatic holding pressure tracking mode of the screw is switched to the time control mode, and an alarm message is issued. When the instantaneous speed movement time of the screw is consistent with the preset instantaneous speed time, it automatically enters the holding pressure stage.

[0083] When the peak value of the screw injection pressure is less than the first-stage holding pressure value, the system is considered to be in a switching state. If the screw injection pressure continues to be lower than the first-stage holding pressure value, it indicates that excessive control of the screw injection pressure is not required in the instantaneous speed control mode. At this time, the system switches the screw's automatic holding pressure tracking mode to the time control mode and issues an alarm message. The alarm message is "The peak value of the screw injection pressure is less than the first-stage holding pressure value, automatically entering the time control mode." When the screw's instantaneous speed control mode is switched to the time control mode, according to the requirements of the time control mode, when the screw's instantaneous speed movement time matches the preset instantaneous speed time, the system automatically enters the holding stage.

[0084] The instantaneous control mode also includes a pressure rise monitoring mode, refer to Figure 6 and Figure 7 , the pressure rise monitoring mode is as follows:

[0085] S31, pressure rise monitoring mode: after the screw enters the instantaneous speed control mode, the pressure rise monitoring mode is turned on to obtain the injection pressure of the screw in real time. If it is detected that the injection pressure of the screw is gradually increasing, the pressure holding stage is immediately entered.

[0086] Specifically, when the instantaneous control mode is set to pressure rise monitoring mode, the system automatically activates this mode. In this mode, the screw's injection pressure is captured in real time. If the screw's injection pressure shows a gradual upward trend, it indicates that the screw's injection pressure is continuously increasing. To prevent the screw from reaching the required pressure quickly after entering the pressure holding phase, the system immediately enters the pressure holding phase when it detects a gradual upward trend in the screw's injection pressure.

[0087] In addition, the instantaneous speed control mode also implements three modes: time control mode, automatic pressure holding tracking mode and pressure rise monitoring mode. When the screw enters the instantaneous speed control mode, the time control mode, automatic pressure holding tracking mode and pressure rise monitoring mode are all turned on. If the screw meets the conditions of any mode in the instantaneous speed control mode, it will switch to the pressure holding stage.

[0088] After entering the instantaneous speed control mode, the following steps are performed on the screw:

[0089] S4. Monitor the injection pressure of the screw that has entered the instantaneous speed control mode, obtain the instantaneous speed pressure of the screw in real time, and compare it with the preset VP switching pressure monitoring value to determine whether the instantaneous speed pressure of the screw is normal.

[0090] When the screw enters the instantaneous speed control mode, the injection pressure will be monitored. The instantaneous speed pressure of the screw in the instantaneous speed control mode is obtained in real time and compared with the preset VP switching pressure monitoring value. Among them, the preset VP switching pressure monitoring value is configured in the system in advance. The screw instantaneous speed pressure is compared with the preset VP switching pressure monitoring value to determine whether the screw instantaneous speed pressure is normal.

[0091] Specifically, refer to Figure 8 , judging whether the screw instantaneous pressure is normal includes the following steps:

[0092] S41. When the instantaneous pressure of the screw does not exceed the preset VP switching pressure monitoring value, it is judged to be normal, and the injection pressure of the screw is continuously monitored until the screw enters the pressure holding stage.

[0093] When the monitored screw instantaneous pressure does not exceed the preset VP switching pressure monitoring value, it means that the screw instantaneous pressure is normal at this time, that is, the screw injection pressure monitoring is continued to obtain the screw instantaneous pressure in real time and compare it to ensure that the screw instantaneous pressure is always in a normal state.

[0094] S42. When the screw instantaneous pressure exceeds the preset VP switching pressure monitoring value, it is judged as abnormal, an alarm signal is issued, and the screw instantaneous pressure is reduced until the screw enters the pressure holding stage.

[0095] When the monitored screw instantaneous pressure exceeds the preset VP switching pressure monitoring value, it means that the screw instantaneous pressure is abnormal and needs to be adjusted. At this time, the system will issue an alarm signal and reduce the screw instantaneous pressure until the screw instantaneous movement time reaches the preset instantaneous time and enters the pressure holding stage.

[0096] In the instantaneous speed control mode, in addition to real-time screw pressure monitoring, the system also calculates the time after the screw enters the instantaneous speed control mode. The specific steps are as follows:

[0097] S5. Obtain the instantaneous speed time of the screw. When the instantaneous speed time of the screw is consistent with the preset instantaneous speed time, perform VP switching on the screw and enter the pressure holding stage.

[0098] When the screw enters the instantaneous speed control mode, the screw instantaneous speed time is obtained. The screw instantaneous speed time is the time the screw stays in the instantaneous speed control mode. When the screw instantaneous speed time is consistent with the preset instantaneous speed time, the screw can be switched to VP and enter the pressure holding stage.

[0099] The examples of this specific embodiment are all preferred embodiments of this application and are not intended to limit the scope of protection of this application. Identical components are represented by the same reference numerals. Therefore, any equivalent changes made based on the structure, shape, and principle of this application should be included in the scope of protection of this application.

Claims

1. A VP switching control method for an all-electric injection molding machine based on an instantaneous speed control mode, characterized in that: The following steps are involved: When the screw enters the injection stage, the screw implements the size priority mode, obtains the screw movement speed in real time, and performs interval control on the screw movement speed before the screw reaches the preset VP switching position; When the screw moves to the automatic deceleration position, it enters the automatic deceleration mode until the screw movement speed reaches zero when it reaches the preset VP switching position; After the screw passes the preset VP switching position, it enters the instantaneous speed control mode, obtains the preset instantaneous speed time and the preset instantaneous speed, and controls the screw according to the preset instantaneous speed time and the preset instantaneous speed. The instantaneous speed control mode includes a time control mode, an automatic pressure maintaining tracking mode, and a pressure rise monitoring mode; Monitor the injection pressure of the screw that enters the instantaneous speed control mode, obtain the instantaneous speed pressure of the screw in real time, and compare it with the preset VP switching pressure monitoring value to determine whether the instantaneous speed pressure of the screw is normal; Obtaining the instantaneous speed time of the screw, and when the instantaneous speed time of the screw is consistent with the preset instantaneous speed time, performing VP switching on the screw and entering the pressure holding stage; The time control mode is that after the screw enters the instantaneous speed control mode, only the instantaneous speed movement time of the screw is monitored, and when the instantaneous speed movement time of the screw is consistent with the preset instantaneous speed time, the pressure holding stage is automatically entered; The automatic pressure-holding tracking mode is to start the pressure-holding tracking mode after the screw enters the instantaneous speed control mode, monitor the screw injection pressure, obtain the first pressure-holding pressure value in the pressure-holding stage, compare the screw injection pressure with the first pressure-holding pressure value, determine the screw pressure state and perform processing; The pressure rise monitoring mode is to start the pressure rise monitoring mode after the screw enters the instantaneous control mode, and obtain the injection pressure of the screw in real time. If it is detected that the injection pressure of the screw is gradually increasing, the pressure holding stage is immediately entered.

2. The VP switching control method of an all-electric injection molding machine based on an instantaneous speed control mode according to claim 1 is characterized in that: The size priority mode means that the screw decelerates in advance before reaching the preset VP switching position and stops at the preset VP switching position.

3. The VP switching control method of an all-electric injection molding machine based on an instantaneous speed control mode according to claim 1 is characterized in that: The preset instantaneous speed time can be set in the range of 10ms-3000ms, and the setting method of the preset instantaneous speed time includes the following three methods: Turn off the system's automatic time calculation function and enter the preset instantaneous speed time in the system before screw injection; Turn on the automatic time calculation function of the system. When the screw enters the instantaneous speed control mode, obtain the total injection time of the screw and the screw speed control running time, and subtract the two to obtain the preset instantaneous speed time; Using standard fixed time, multiple modes are set in the system with a time range of 10ms-3000ms. The system automatically executes according to the requirements of multiple modes.

4. The VP switching control method of an all-electric injection molding machine based on an instantaneous speed control mode according to claim 1 is characterized in that: The preset instantaneous speed is the running speed of the screw after entering the instantaneous speed control mode.

5. The VP switching control method of an all-electric injection molding machine based on an instantaneous speed control mode according to claim 1 is characterized in that: The instantaneous screw pressure is obtained in real time and compared with the preset VP switching pressure monitoring value to determine whether the instantaneous screw pressure is normal, including the following steps: When the instantaneous pressure of the screw does not exceed the preset VP switching pressure monitoring value, it is judged to be normal, and the injection pressure of the screw is continuously monitored until the screw enters the holding pressure stage; When the screw instantaneous pressure exceeds the preset VP switching pressure monitoring value, it is judged as abnormal, an alarm signal is issued, and the screw instantaneous pressure is reduced until the screw enters the pressure holding stage.

6. The VP switching control method of an all-electric injection molding machine based on an instantaneous speed control mode according to claim 1 is characterized in that: The step of comparing the screw injection pressure with the first-stage holding pressure value to determine the screw pressure state and perform processing includes the following steps: When the peak value of the screw injection pressure is greater than the first stage holding pressure value, it is determined to be in a pressure reduction state, and the screw is subjected to a pressure reduction operation until the screw injection pressure reaches the first stage holding pressure value, and then the holding stage is automatically entered; When the peak value of the screw injection pressure is less than the first-stage holding pressure value, it is determined to be in a switching state, the automatic holding pressure tracking mode of the screw is switched to the time control mode, and an alarm message is issued. When the screw instantaneous speed movement time of the screw is consistent with the preset instantaneous speed time, the holding pressure stage is automatically entered.

7. The VP switching control method of an all-electric injection molding machine based on an instantaneous speed control mode according to claim 1 is characterized in that: When the screw enters the instantaneous speed control mode, the time control mode, the automatic pressure holding tracking mode and the pressure rise monitoring mode are all turned on, and if the screw meets the conditions of any mode in the instantaneous speed control mode, it switches to the pressure holding stage.

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