A method for detecting cavity pressure of die casting mold

Abstract

The present invention discloses a system and method for detecting the cavity pressure of a die-casting mold, which relates to the field of measurement technology. The detection system includes a fixed component and a measuring component. The fixed component includes a movable mold core and a push rod pressure plate that are spaced apart, and the front end of the movable mold core is provided with a cavity; the measuring component includes a push rod and a pressure sensor located on the push rod pressure plate. One end of the push rod can movably pass through the movable mold core and extend into the cavity, while the other end abuts against the pressure sensor on the push rod pressure plate. The fixed component also includes a movable mold frame located behind the movable mold core, and a push rod mounting plate located at the push rod pressure plate. One end of the push rod passes through the movable mold frame and the movable mold core and extends into the cavity, while the other end passes through the push rod mounting plate and abuts against the pressure sensor. The present invention can obtain an accurate cavity pressure value, effectively monitor the actual pressure to which the molten metal in the cavity is subjected, and help control the quality of castings.

Description

Technical Field

[0001] The present invention relates to the field of measurement technology, and in particular to a system and method for detecting the cavity pressure of a die-casting mold. Background Art

[0002] High-pressure casting involves solidifying molten metal under pressure. The pressure exerted on the molten metal within the mold cavity is referred to as cavity pressure. The higher the cavity pressure within a reasonable range, the denser the solidified casting and the fewer internal defects. Therefore, cavity pressure is a crucial parameter in the high-pressure casting process and requires careful monitoring. Cavity pressure is generated by the hydraulic oil in the die-casting machine's injection cylinder pushing the piston, which in turn pushes the shot rod. The other end of the shot rod is connected to a punch, which applies pressure to the molten metal, generating internal pressure.

[0003] Currently, cavity pressure testing is performed by measuring the hydraulic oil pressure and converting it into a theoretical value. Specifically, the pressure of the oil in the hydraulic cylinder of the die-casting machine is measured, and the internal pressure of the molten metal is calculated based on the cross-sectional area of ​​the hydraulic cylinder piston, the pressure of the piston on the injection rod, the pressure of the injection punch on the molten metal, and the cross-sectional area of ​​the injection punch. However, this testing method has the following drawbacks:

[0004] 1. The molten metal directly subjected to the punch pressure is only the molten metal in the mold runner, which is then indirectly transferred to the molten metal in the cavity. Since the runner width is generally narrow, the molten metal in the runner may solidify locally first, resulting in pressure transmission attenuation, making the actual cavity pressure lower than the calculated theoretical value;

[0005] 2. The punch is a movable part that moves in the pressure chamber. After the two are worn, the fitting gap expands. The molten metal may seep out of the gap and condense on the side wall of the pressure chamber, causing the punch to jam and affecting the pressure transmission, resulting in the actual cavity pressure being less than the calculated theoretical value. Summary of the Invention

[0006] In response to the defects existing in the prior art, the purpose of the present invention is to provide a system and method for detecting the cavity pressure of a die-casting mold, which can obtain accurate cavity pressure values, effectively monitor the actual pressure exerted on the molten metal in the cavity, and help control the quality of castings.

[0007] To achieve the above objectives, the present invention provides a system for detecting the cavity pressure of a die-casting mold, comprising:

[0008] A fixed assembly, the fixed assembly comprising a movable mold core and a push rod pressure plate arranged at intervals, the front end of the movable mold core being provided with a cavity;

[0009] The measuring assembly includes a push rod and a pressure sensor located on the push rod pressure plate. One end of the push rod can move through the movable mold core and extend into the mold cavity, and the other end abuts against the pressure sensor on the push rod pressure plate.

[0010] Based on the above technical solution, the fixing assembly also includes a movable mold frame located behind the movable mold core, and a push rod mounting plate located at the push rod pressure plate. One end of the push rod passes through the movable mold frame and the movable mold core and extends into the mold cavity, and the other end passes through the push rod mounting plate and rests on the pressure sensor.

[0011] On the basis of the above technical solution, the detection system further includes a data acquisition and display terminal, and the data acquisition and display terminal is electrically connected to the pressure sensor.

[0012] The present invention provides a method for detecting the cavity pressure of a die-casting mold, which is implemented based on the above-mentioned detection system and specifically includes the following steps:

[0013] Based on the pressure value detected by the pressure sensor after the molten metal fills the cavity, the cavity pressure measurement values ​​at different times are calculated;

[0014] According to the cavity pressure measurement value at the current moment and the true value of the cavity pressure at the current moment, the variance value of the cavity pressure measurement error is obtained;

[0015] Based on the measurement error covariance at the current moment, the confidence level of the cavity pressure measurement value is calculated;

[0016] The estimated value of the cavity pressure at the current moment is calculated based on the confidence level of the cavity pressure measurement value, the state value at the current moment and the cavity pressure measurement value at the current moment. The state value at the current moment is the cavity pressure predicted at the current moment using the cavity pressure measurement value at the previous moment.

[0017] On the basis of the above technical solution, the pressure value is obtained by the pressure sensor after the molten metal fills the cavity, and the specific steps include:

[0018] The cavity is filled with molten metal, which hits the ejector pin;

[0019] The molten metal generates cavity pressure and exerts pressure on the ejector pin after being subjected to the punch pressure.

[0020] The ejector rod transmits the real-time pressure to the tail end of the ejector rod and applies the pressure to the pressure sensor, which detects the pressure value.

[0021] On the basis of the above technical solution, the calculation obtains the cavity pressure measurement values ​​at different times, wherein the cavity pressure measurement values ​​are calculated as follows:

[0022] P2=F3 / S3

[0023] Among them, P2 represents the measured value of the cavity pressure, F3 represents the pressure exerted on the ejector pin, that is, the pressure value detected by the pressure sensor, and S3 represents the cross-sectional area of ​​the ejector pin.

[0024] On the basis of the above technical solution, the variance value of the cavity pressure measurement error is obtained according to the current cavity pressure measurement value and the current cavity pressure true value. The specific calculation method is:

[0025] z(k)=x(k)+v(k)

[0026] x(k)=Ax(k-1)+Bu(k-1)

[0027] Among them, z(k) represents the measured value of the cavity pressure at the current moment, x(k) represents the true value of the cavity pressure at the current moment, v(k) represents the variance value of the cavity pressure measurement error, A and B both represent constants, x(k-1) represents the true value of the cavity pressure at the previous moment, and u(k-1) represents the cavity pressure control value at the previous moment.

[0028] On the basis of the above technical solution, the reliability of the cavity pressure measurement value is calculated based on the measurement error covariance at the current moment. The specific calculation method is:

[0029] Kg=P(k|k-1) / (P(k|k-1)+R)

[0030] Where Kg represents the confidence level of the cavity pressure measurement value, P(k|k-1) represents the measurement error covariance predicted by using the cavity pressure measurement value at the previous moment, and R represents the measurement error coefficient of the cavity pressure.

[0031] Based on the above technical solution, the specific calculation method for the measurement error covariance at the current moment is:

[0032] x(k|k-1)=x(k-1|k-1)

[0033] P(k|k-1)=P(k-1|k-1)+Q

[0034] Among them, x(k|k-1) means using the cavity pressure measurement value at the previous moment to predict the cavity pressure at the current moment, x(k-1|k-1) means using the cavity pressure measurement value at the previous moment to predict the cavity pressure at the previous moment, P(k-1|k-1) means using the cavity pressure measurement value at the previous moment to predict the measurement error covariance at the previous moment, and Q means the confidence level of the cavity pressure estimate.

[0035] On the basis of the above technical solution, the cavity pressure estimation value at the current moment is calculated based on the cavity pressure measurement value confidence level, the current state value and the current cavity pressure measurement value. The specific calculation method is:

[0036] x(k|k)=(1-Kg)·x(k|k-1)+Kg·z(k)

[0037] Where x(k|k) represents the estimated value of the cavity pressure at the current moment.

[0038] Compared with the existing technology, the advantages of the present invention are: through the setting of the push rod, the pressure at the end of the push rod can be directly obtained, which solves the inaccuracy, non-real-time and measurement uncertainty problems of the indirect measurement scheme. It can perform instantaneous detection within the window time and obtain accurate cavity pressure values ​​in real time, effectively monitoring the actual pressure of the molten metal in the cavity, which helps to control the quality of castings. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0040] Figure 1 Schematic diagram of the structure of a system for detecting the cavity pressure of a die-casting mold according to an embodiment of the present invention;

[0041] Figure 2 for Figure 1 A magnified schematic diagram of point A in the middle;

[0042] Figure 3 The figure is a flow chart of a method for detecting the cavity pressure of a die-casting mold according to an embodiment of the present invention. DETAILED DESCRIPTION

[0043] In order to make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. It should be noted that the orientation or position relationship indicated by the terms "upper" and "lower" is based on the orientation or position relationship shown in the drawings, which is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present application. 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 it can be indirectly connected through an intermediate medium, or it can be a communication between the two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to the specific circumstances. In this application, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "comprises", "comprising" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or apparatus comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article or apparatus. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of additional identical elements in the process, method, article or apparatus comprising the element.

[0044] See also Figure 1 As shown, embodiments of the present invention provide a system for detecting die-casting mold cavity pressure. This system addresses the current indirect measurement and conversion methods, which fail to accurately represent the actual metal fluid pressure in the cavity using theoretical cavity pressure values, cannot detect pressure in real time, and cannot eliminate measurement equipment errors. The die-casting mold cavity pressure detection system includes a fixed component and a measuring component.

[0045] The fixed assembly includes a movable mold core and a push rod pressure plate, which are spaced apart. The front end of the movable mold core is provided with a mold cavity. The measuring assembly includes a push rod and a pressure sensor located on the push rod pressure plate. One end of the push rod can move through the movable mold core and extend into the mold cavity, while the other end abuts against the pressure sensor on the push rod pressure plate. For the specific arrangement of the pressure sensor, please refer to Figure 2 shown.

[0046] Furthermore, the fixed assembly also includes a movable mold frame located behind the movable mold core, and a push rod mounting plate located at the push rod pressure plate. One end of the push rod passes through the movable mold frame and movable mold core, extending into the mold cavity, while the other end passes through the push rod mounting plate and abuts against the pressure sensor. Once the push rod is positioned within the movable mold frame, movable mold core, and push rod mounting plate, it can move freely along its length, thereby transmitting the pressure in the mold cavity to the pressure sensor at the rear end of the push rod, thereby measuring the cavity pressure.

[0047] Furthermore, the die-casting mold cavity pressure detection system also includes a data acquisition and display terminal, and the data acquisition and display terminal is electrically connected to the pressure sensor, that is, the data acquisition and display terminal is connected to the pressure sensor through a signal line. Figure 1 In the figure, number 1 represents the cavity, number 2 represents the movable mold core, number 3 represents the movable mold frame, number 4 represents the ejector pin, number 5 represents the ejector pin mounting plate, number 6 represents the ejector pin pressure plate, number 8 represents the signal line, and number 9 represents the data acquisition and display terminal. Figure 2 In the figure, reference numeral 7 denotes a pressure sensor.

[0048] The specific use process of the detection system of the present invention is described as follows: fix the pressure sensor to the tail end of the ejector pin, install the pressure sensor on the ejector pin mounting plate, and use the ejector pin pressure plate to press the pressure sensor; connect the data acquisition and display terminal to the pressure sensor through a signal line, the data acquisition and display terminal receives the voltage signal of the pressure sensor, and the data acquisition and display terminal performs a peeling and zeroing operation; install the ejector pin mounting plate on the movable mold frame of the mold to be tested, and the ejector pin passes through the ejector pin holes on the movable mold frame and the movable mold core and extends into the mold cavity. When installing, apply lubricating oil on the ejector pin to reduce the friction of the movement in the ejector pin hole. At this time, the detection system is Installation is completed; production of die-cast parts begins, the molten metal fills the cavity of the mold and contacts the ejector pin. The molten metal generates cavity pressure after being subjected to the pressure of the punch, which generates pressure on the ejector pin. The cross-sectional area of ​​the ejector pin is S3, and the cavity pressure to be measured is P2. The ejector pin is subjected to pressure F3 = S3 × P2; the ejector pin transmits real-time pressure to the tail end and applies it to the pressure sensor, and the pressure sensor 7 receives the pressure value in real time; the pressure sensor detects the pressure, converts it into a voltage signal, and transmits it to the data acquisition and display terminal through the signal line. The signal is displayed after processing, and the pressure F3 of the ejector pin at a certain moment can be displayed. Then the cavity pressure to be measured at this moment is P2 = F3 / S3.

[0049] The present invention directly obtains the pressure at the end of the push rod through the setting of the push rod, which solves the inaccuracy, non-real-time and measurement uncertainty problems of the indirect measurement scheme. It can perform instantaneous detection within the window time and obtain accurate cavity pressure values ​​in real time, effectively monitoring the actual pressure of the molten metal in the cavity, which helps to control the quality of castings.

[0050] See also Figure 3As shown, an embodiment of the present invention provides a method for detecting the cavity pressure of a die-casting mold, which is implemented based on the above-mentioned detection system. The detection method specifically includes the following steps:

[0051] S1: Based on the pressure value detected by the pressure sensor after the molten metal fills the cavity, the cavity pressure measurement values ​​at different times are calculated;

[0052] In the present invention, the pressure value is obtained by detecting the pressure sensor after the molten metal fills the cavity, and the specific steps include:

[0053] S101: The cavity is filled with molten metal, and the molten metal hits the ejector pin;

[0054] S102: The molten metal generates cavity pressure after being subjected to the punch pressure and exerts pressure on the ejector pin;

[0055] S103: The ejector rod transmits the real-time pressure to the tail end of the ejector rod and applies the pressure to the pressure sensor, which detects and obtains the pressure value.

[0056] In the present invention, the cavity pressure measurement values ​​at different times are calculated, wherein the cavity pressure measurement values ​​are calculated as follows:

[0057] P2=F3 / S3

[0058] Among them, P2 represents the measured value of the cavity pressure, F3 represents the pressure exerted on the ejector pin, that is, the pressure value detected by the pressure sensor, and S3 represents the cross-sectional area of ​​the ejector pin.

[0059] Specifically, fix the pressure sensor to the tail end of the ejector pin, install the pressure sensor on the ejector pin mounting plate, and use the ejector pin pressure plate to press the pressure sensor; connect the data acquisition and display terminal to the pressure sensor through the signal line, the data acquisition and display terminal receives the voltage signal of the pressure sensor, and performs the tare and zero reset operation on the data acquisition and display terminal; install the ejector pin mounting plate on the movable mold frame of the mold to be tested, and the ejector pin passes through the ejector pin holes on the movable mold frame and the movable mold core and extends into the cavity. When installing, apply lubricating oil on the ejector pin to reduce the friction of the movement in the ejector pin hole. At this time, the detection system is installed; start production For die castings, the molten metal fills the cavity of the mold and contacts the ejector pin. The molten metal generates cavity pressure after being subjected to the pressure of the punch, which generates pressure on the ejector pin. The cross-sectional area of ​​the ejector pin is S3, and the cavity pressure to be measured is P2. The ejector pin is subjected to pressure F3=S3×P2; the ejector pin transmits real-time pressure to the tail end and applies it to the pressure sensor, and the pressure sensor 7 receives the pressure value in real time; the pressure sensor detects the pressure, converts it into a voltage signal, and transmits it to the data acquisition and display terminal through the signal line. The signal is displayed after processing, and the pressure F3 of the ejector pin at a certain moment can be displayed. Then the cavity pressure to be measured at this moment is P2=F3 / S3.

[0060] S2: Obtain the variance of the cavity pressure measurement error based on the current cavity pressure measurement value and the current cavity pressure true value;

[0061] In the present invention, the variance of the cavity pressure measurement error is obtained based on the current cavity pressure measurement value and the current cavity pressure true value. The specific calculation method is:

[0062] z(k)=x(k)+v(k)

[0063] x(k)=Ax(k-1)+Bu(k-1)

[0064] Among them, z(k) represents the measured value of the cavity pressure at the current moment, x(k) represents the true value of the cavity pressure at the current moment, v(k) represents the variance value of the cavity pressure measurement error, A and B both represent constants, x(k-1) represents the true value of the cavity pressure at the previous moment, and u(k-1) represents the cavity pressure control value at the previous moment, that is, the control value input by the measurement system in order to change the state at the previous moment.

[0065] S3: Based on the measurement error covariance at the current moment, the confidence level of the cavity pressure measurement value is calculated;

[0066] In the present invention, the confidence level of the cavity pressure measurement value is calculated based on the measurement error covariance at the current moment. The specific calculation method is:

[0067] Kg=P(k|k-1) / (P(k|k-1)+R)

[0068] Where Kg represents the confidence level of the cavity pressure measurement value, P(k|k-1) represents the measurement error covariance predicted by using the cavity pressure measurement value at the previous moment, and R represents the measurement error coefficient of the cavity pressure.

[0069] In the present invention, the specific calculation method for the measurement error covariance at the current moment is:

[0070] x(k|k-1)=x(k-1|k-1)

[0071] P(k|k-1)=P(k-1|k-1)+Q

[0072] Among them, x(k|k-1) means using the cavity pressure measurement value at the previous moment to predict the cavity pressure at the current moment, x(k-1|k-1) means using the cavity pressure measurement value at the previous moment to predict the cavity pressure at the previous moment, P(k-1|k-1) means using the cavity pressure measurement value at the previous moment to predict the measurement error covariance at the previous moment, and Q means the confidence level of the cavity pressure estimate. The larger the Q, the more confidence the estimate has.

[0073] S4: Calculate the estimated value of the cavity pressure at the current moment based on the confidence level of the cavity pressure measurement value, the state value at the current moment, and the cavity pressure measurement value at the current moment. The state value at the current moment is the cavity pressure at the current moment predicted by the cavity pressure measurement value at the previous moment.

[0074] In the present invention, the estimated value of the cavity pressure at the current moment is calculated based on the confidence level of the cavity pressure measurement value, the current state value, and the current cavity pressure measurement value. The specific calculation method is:

[0075] x(k|k)=(1-Kg)·x(k|k-1)+Kg·z(k)

[0076] Where x(k|k) represents the estimated value of the cavity pressure at the current moment.

[0077] The detection method of the present invention is described in detail as follows:

[0078] 1. After obtaining the cavity pressure measurement values ​​at different times, within the continuous stable measurement time range, the true value of the cavity pressure at a certain moment is recorded as x(k), then:

[0079] x(k)=Ax(k-1)+Bu(k-1);

[0080] 2. At this moment, the measurement system can measure a cavity pressure value, namely:

[0081] z(k)=x(k)+v(k);

[0082] 3. After a calculation cycle, measure the system state change:

[0083] x(k|k-1)=x(k-1|k-1)

[0084] P(k|k-1)=P(k-1|k-1)+Q;

[0085] Update the formula to get:

[0086] Kg=P(k|k-1) / (P(k|k-1)+R)

[0087] The estimated value of the cavity pressure at the current moment is:

[0088] x(k|k)=(1-Kg)·x(k|k-1)+Kg·z(k);

[0089] Furthermore, P(k|k)=(1-Kg)·P(k|k-1), where P(k|k) represents the measurement error covariance at the current moment.

[0090] The method for detecting the cavity pressure of the die-casting mold of the present invention can solve the inaccuracy, non-real-time and measurement uncertainty problems of indirect measurement solutions. It can perform instantaneous detection within the window time and obtain accurate cavity pressure values ​​in real time, effectively monitoring the actual pressure of the molten metal in the cavity, which helps to control the quality of castings.

[0091] In one possible implementation, an embodiment of the present invention further provides a readable storage medium, which is located in a PLC (Programmable Logic Controller) controller. The readable storage medium stores a computer program, which, when executed by a processor, implements the following steps of the method for detecting the cavity pressure of a die-casting mold:

[0092] Based on the pressure value detected by the pressure sensor after the molten metal fills the cavity, the cavity pressure measurement values ​​at different times are calculated;

[0093] According to the cavity pressure measurement value at the current moment and the true value of the cavity pressure at the current moment, the variance value of the cavity pressure measurement error is obtained;

[0094] Based on the measurement error covariance at the current moment, the confidence level of the cavity pressure measurement value is calculated;

[0095] The estimated value of the cavity pressure at the current moment is calculated based on the confidence level of the cavity pressure measurement value, the state value at the current moment, and the cavity pressure measurement value at the current moment.

[0096] In the present invention, the pressure value is obtained by detecting the pressure sensor after the molten metal fills the cavity. The specific process includes:

[0097] The cavity is filled with molten metal, which hits the ejector pin;

[0098] The molten metal generates cavity pressure and exerts pressure on the ejector pin after being subjected to the punch pressure.

[0099] The ejector rod transmits the real-time pressure to the tail end of the ejector rod and applies the pressure to the pressure sensor, which detects the pressure value.

[0100] In the present invention, the cavity pressure measurement values ​​at different times are calculated, wherein the cavity pressure measurement values ​​are calculated as follows:

[0101] P2=F3 / S3

[0102] Among them, P2 represents the measured value of the cavity pressure, F3 represents the pressure exerted on the ejector pin, that is, the pressure value detected by the pressure sensor, and S3 represents the cross-sectional area of ​​the ejector pin.

[0103] The present invention directly obtains the pressure at the end of the push rod through the setting of the push rod, which solves the inaccuracy, non-real-time and measurement uncertainty problems of the indirect measurement scheme. It can perform instantaneous detection within the window time and obtain accurate cavity pressure values ​​in real time, effectively monitoring the actual pressure of the molten metal in the cavity, which helps to control the quality of castings.

[0104] The storage medium can adopt any combination of one or more computer-readable media. The computer-readable medium can be a computer-readable signal medium or a computer-readable storage medium. The computer-readable storage medium can be, for example, but not limited to: an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, device or component, or any combination of the above. More specific examples (non-exhaustive list) of computer-readable storage media include: an electrical connection with one or more wires, a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the above. In this document, a computer-readable storage medium can be any tangible medium containing or storing a program that can be used by or in conjunction with an instruction execution system, device or device.

[0105] A computer-readable signal medium may include a data signal propagated in baseband or as part of a carrier wave, which carries computer-readable program code. Such propagated data signals may take a variety of forms, including but not limited to electromagnetic signals, optical signals, or any suitable combination thereof. A computer-readable signal medium may also be any computer-readable medium other than a computer-readable storage medium, which may transmit, propagate, or transfer a program for use by or in conjunction with an instruction execution system, apparatus, or device. The program code contained on the computer-readable medium may be transmitted using any suitable medium, including but not limited to wireless, wire, optical cable, RF, etc., or any suitable combination thereof.

[0106] Computer program code for performing the operations of the present invention can be written in one or more programming languages, or a combination thereof, including object-oriented programming languages ​​such as Java, Smalltalk, C++, and conventional procedural programming languages ​​such as "C" or similar programming languages. The program code can be executed entirely on the user's computer, partially on the user's computer, as a stand-alone software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In cases involving a remote computer, the remote computer can be connected to the user's computer through any type of network, including a local area network (LAN) or a wide area network (WAN), or can be connected to an external computer (e.g., through the Internet using an Internet service provider).

[0107] An embodiment of the present invention also provides a system for detecting the cavity pressure of a die-casting mold, comprising a first calculation module, a second calculation module, a third calculation module, and an execution module. The first calculation module is used to calculate the cavity pressure measurement values ​​at different times based on the pressure value detected by the pressure sensor after the molten metal fills the cavity; the second calculation module is used to obtain the variance value of the cavity pressure measurement error based on the cavity pressure measurement value at the current moment and the true value of the cavity pressure at the current moment; the third calculation module is used to calculate the confidence level of the cavity pressure measurement value based on the measurement error covariance at the current moment; and the execution module is used to calculate the estimated cavity pressure value at the current moment based on the confidence level of the cavity pressure measurement value, the current state value, and the cavity pressure measurement value at the current moment.

[0108] In the present invention, the pressure value is obtained by detecting the pressure sensor after the molten metal fills the cavity. The specific process includes:

[0109] The cavity is filled with molten metal, which hits the ejector pin;

[0110] The molten metal generates cavity pressure and exerts pressure on the ejector pin after being subjected to the punch pressure.

[0111] The ejector rod transmits the real-time pressure to the tail end of the ejector rod and applies the pressure to the pressure sensor, which detects the pressure value.

[0112] In the present invention, the cavity pressure measurement values ​​at different times are calculated, wherein the cavity pressure measurement values ​​are calculated as follows:

[0113] P2=F3 / S3

[0114] Among them, P2 represents the measured value of the cavity pressure, F3 represents the pressure exerted on the ejector pin, that is, the pressure value detected by the pressure sensor, and S3 represents the cross-sectional area of ​​the ejector pin.

[0115] In the present invention, the variance of the cavity pressure measurement error is obtained based on the current cavity pressure measurement value and the current cavity pressure true value. The specific calculation method is:

[0116] z(k)=x(k)+v(k)

[0117] x(k)=Ax(k-1)+Bu(k-1)

[0118] Among them, z(k) represents the measured value of the cavity pressure at the current moment, x(k) represents the true value of the cavity pressure at the current moment, v(k) represents the variance value of the cavity pressure measurement error, A and B both represent constants, x(k-1) represents the true value of the cavity pressure at the previous moment, and u(k-1) represents the cavity pressure control value at the previous moment.

[0119] In the description of this application, it should be noted that the terms "upper" and "lower" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on this application. 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, or it can be internal communication between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to the specific circumstances.

[0120] It should be noted that, in this application, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "comprising a ..." does not exclude the presence of other identical elements in the process, method, article or device comprising the element.

[0121] The foregoing is merely a list of specific embodiments of the present application, intended to enable those skilled in the art to understand or implement the present application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application is not limited to the embodiments shown herein, but is intended to conform to the broadest scope consistent with the principles and novel features of the present application.

Claims

1. A method for detecting the cavity pressure of a die-casting mold, which is implemented based on a detection system for the cavity pressure of a die-casting mold, and is characterized in that: The specific steps include: Based on the pressure value detected by the pressure sensor after the molten metal fills the cavity, the cavity pressure measurement values ​​at different times are calculated; According to the cavity pressure measurement value at the current moment and the true value of the cavity pressure at the current moment, the variance value of the cavity pressure measurement error is obtained; Based on the measurement error covariance at the current moment, the confidence level of the cavity pressure measurement value is calculated; Calculating an estimated value of the cavity pressure at the current moment based on the cavity pressure measurement value confidence level, the current state value, and the current cavity pressure measurement value, wherein the current state value is the cavity pressure predicted at the current moment using the previous cavity pressure measurement value; Wherein, the detection system based on the die-casting mold cavity pressure includes a fixing component and a measuring component, the fixing component includes a movable mold core and a push rod pressure plate arranged at intervals, the front end of the movable mold core is provided with a cavity, the measuring component includes a push rod and a pressure sensor located on the push rod pressure plate, one end of the push rod can movably pass through the movable mold core and extend into the cavity, and the other end abuts against the pressure sensor of the push rod pressure plate, the fixing component also includes a movable mold frame located behind the movable mold core, and a push rod mounting plate located at the push rod pressure plate, one end of the push rod passes through the movable mold frame and the movable mold core and extends into the cavity, and the other end passes through the push rod mounting plate and abuts against the pressure sensor, the detection system also includes a data acquisition and display terminal, and the data acquisition and display terminal is electrically connected to the pressure sensor; The variance of the cavity pressure measurement error is obtained based on the current cavity pressure measurement value and the current cavity pressure true value. The specific calculation method is: z(k)=x(k)+v(k) x(k)=Ax(k-1)+Bu(k-1) Wherein, z(k) represents the measured value of the cavity pressure at the current moment, x(k) represents the true value of the cavity pressure at the current moment, v(k) represents the variance of the cavity pressure measurement error, A and B represent constants, x(k-1) represents the true value of the cavity pressure at the previous moment, and u(k-1) represents the cavity pressure control value at the previous moment; The confidence level of the cavity pressure measurement value is calculated based on the measurement error covariance at the current moment. The specific calculation method is: Kg =P(k|k-1) / (P(k|k-1) +R) Where Kg represents the confidence level of the cavity pressure measurement value, P(k|k-1) represents the measurement error covariance of the cavity pressure measurement value at the previous moment to predict the current moment, and R represents the measurement error coefficient of the cavity pressure. Among them, the specific calculation method for the measurement error covariance at the current moment is: x(k|k-1)=x(k-1|k-1) P(k|k-1) = P(k-1|k-1)+Q Among them, x(k|k-1) means using the cavity pressure measurement value at the previous moment to predict the cavity pressure at the current moment, x(k-1|k-1) means using the cavity pressure measurement value at the previous moment to predict the cavity pressure at the previous moment, P(k-1|k-1) means using the cavity pressure measurement value at the previous moment to predict the measurement error covariance of the previous moment, and Q means the confidence of the cavity pressure estimate. The estimated value of the cavity pressure at the current moment is calculated based on the confidence level of the cavity pressure measurement value, the current state value, and the current cavity pressure measurement value. The specific calculation method is: x(k|k) = (1-Kg)·x(k|k-1)+ Kg·z(k) Where x(k|k) represents the estimated value of the cavity pressure at the current moment.

2. A method for detecting the cavity pressure of a die-casting mold according to claim 1, characterized in that: The pressure value is obtained by the pressure sensor after the molten metal fills the cavity, and the specific steps include: The cavity is filled with molten metal, which hits the ejector pin; The molten metal generates cavity pressure and exerts pressure on the ejector pin after being subjected to the punch pressure. The ejector rod transmits the real-time pressure to the tail end of the ejector rod and applies the pressure to the pressure sensor, which detects the pressure value.

3. A method for detecting the cavity pressure of a die-casting mold according to claim 2, characterized in that: The calculation obtains the cavity pressure measurement values ​​at different times, wherein the cavity pressure measurement values ​​are calculated as follows: P2=F3 / S3 Among them, P2 represents the measured value of the cavity pressure, F3 represents the pressure exerted on the ejector pin, that is, the pressure value detected by the pressure sensor, and S3 represents the cross-sectional area of ​​the ejector pin.

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