A hydraulic pressure shaft controller-based injection control method for a die casting machine

Abstract

The application discloses a die casting machine injection control method based on a hydraulic shaft controller and relates to the field of die casting machine control. The method comprises the following steps: a processor including a first kernel for logic processing and a second kernel for real-time motion control is adopted; a motion command issued by a die casting machine controller is received by the first kernel; a speed control instruction sequence and a pressure control instruction sequence corresponding to an injection shaft are obtained by analysis; the speed control instruction sequence and the pressure control instruction sequence are combined with corresponding speed closed-loop control parameters and pressure closed-loop control parameters respectively to form a motion data block which is then sent to the second kernel; the second kernel executes speed closed-loop control and pressure closed-loop control in a preset control period according to the motion data block; and a generated speed or pressure control signal is output to a corresponding speed servo valve module or a pressure servo valve module via an analog output module, so that resource isolation and time sequence decoupling of logic processing tasks and real-time motion control tasks are realized in the processor.

Description

Technical Field

[0001] This invention relates to the field of die casting machine control, and more particularly to a die casting machine injection control method based on a hydraulic shaft controller. Background Technology

[0002] Die casting machines are metal forming equipment widely used in the automotive, electronics, and aerospace industries. Their working principle involves injecting molten metal into a mold cavity under high pressure and high speed in a very short time, followed by rapid cooling and solidification under pressure, resulting in metal castings with complex structures and precise dimensions. In recent years, with the accelerating trend towards lightweighting in new energy vehicles and the widespread adoption of integrated large die-cast structural components (such as vehicle chassis), higher requirements have been placed on the speed control precision, pressure response speed, and process consistency of the die casting process.

[0003] Traditional die-casting machines mostly use hydraulic systems composed of on / off valves or ordinary proportional valves. These systems have low control bandwidth, slow response, and poor steady-state performance, making it difficult to achieve stable speed control during the high-speed filling stage and to seamlessly switch from speed mode to pressure mode within milliseconds at the end of the filling process. Speed ​​fluctuations can easily lead to defects such as air entrapment and cold shuts, while delayed pressure build-up directly affects the density and mechanical properties of the castings, severely restricting the yield and production efficiency of high-end die-cast parts.

[0004] To overcome the aforementioned bottlenecks, valve-controlled hydraulic systems based on high-frequency response proportional servo valves are gradually becoming the development direction of modern high-performance die-casting machines. This technology continuously and precisely regulates flow and pressure through servo valves, theoretically achieving high dynamic and high-precision injection control. However, the actual performance of a servo valve control system depends not only on the frequency response characteristics of the valve itself, but also on the real-time performance of the control algorithm, the processing capability of feedback signals, and the collaborative efficiency of the hardware and software architecture. Existing controllers mostly adopt a single-core processor architecture, which is prone to computational bottlenecks when simultaneously handling communication, instruction parsing, and dual closed-loop (speed / pressure) real-time control tasks. This leads to control cycle jitter and closed-loop delays, failing to fully realize the performance potential of the servo valve. Summary of the Invention

[0005] To overcome the problems of lag, insufficient control accuracy, and poor real-time performance in traditional die-casting machine hydraulic systems during high-speed injection and rapid pressurization switching, and to fully leverage the dynamic performance advantages of high-frequency response proportional servo valves, this invention proposes a die-casting machine injection control method based on a hydraulic shaft controller. The die-casting machine includes one or more injection shafts; the hydraulic shaft controller includes a processor and an analog output module; the processor includes a first core for logic processing and a second core for real-time motion control; the method includes:

[0006] The first core receives motion commands from the die-casting machine controller, corresponding to each injection axis. For each motion command:

[0007] The motion command is parsed to obtain the speed control command sequence and pressure control command sequence of the corresponding injection axis; the speed control command sequence, pressure control command sequence, speed closed-loop control parameters and pressure closed-loop control parameters are combined and encapsulated into a motion data block and sent to the second kernel;

[0008] Through the second core, based on the motion data block corresponding to each injection axis, speed closed-loop control and pressure closed-loop control are performed on the corresponding injection axis within a preset control cycle. According to the type of closed-loop control currently being performed, the corresponding control signal is output to the speed servo valve module or pressure boosting servo valve module of the corresponding injection axis via the analog output module to adjust the speed of the injection piston or the pressure of the boosting cylinder.

[0009] Furthermore, the second core performs speed closed-loop control and pressure closed-loop control on the corresponding injection axis within a preset control cycle based on the motion data block corresponding to each injection axis, and outputs corresponding control signals to the speed servo valve module or pressure boosting servo valve module of the corresponding injection axis via the analog output module according to the currently executed closed-loop control type, including:

[0010] For each injection axis:

[0011] Based on its corresponding speed control command sequence, speed closed-loop control parameters and its injection piston position feedback signal, speed closed-loop control is executed to generate speed control signal, which is then output to the speed servo valve module corresponding to the injection shaft via the analog output module.

[0012] When the position feedback signal of the injection piston of the injection shaft meets the preset pressure boosting trigger condition, pressure closed-loop control is executed to generate a pressure control signal according to the pressure control command sequence, pressure closed-loop control parameters and pressure feedback signal corresponding to the injection shaft, and then output to the pressure boosting servo valve module corresponding to the injection shaft through the analog output module.

[0013] Furthermore, the motion command includes a speed command data block and a boost command data block.

[0014] Furthermore, the process of parsing the motion command to obtain the corresponding speed control command sequence and pressure control command sequence for the injection axis includes:

[0015] The speed command data block is parsed to extract multiple position parameters, speed parameters corresponding to each position parameter, and acceleration parameters corresponding to each position parameter. The position parameters, corresponding speed parameters, and corresponding acceleration parameters are grouped into multiple data items according to their one-to-one correspondence, and the multiple data items are arranged in the order of the injection stroke to form a speed control command sequence.

[0016] The pressurization command data block is parsed to extract multiple time parameters and pressure parameters that correspond one-to-one with each time parameter; the time parameters and the corresponding pressure parameters are grouped into multiple data items according to their one-to-one correspondence, and the multiple data items are arranged in chronological order to form a pressure control command sequence.

[0017] Furthermore, the hydraulic shaft controller also includes:

[0018] The analog input module is used to acquire the pressure feedback signal of the booster cylinder of each injection shaft and provide the pressure feedback signal to the second core for pressure closed-loop control;

[0019] The signal input module is used to collect the injection piston position feedback signal of each injection axis and provide the injection piston position feedback signal to the second core for speed closed-loop control.

[0020] Furthermore, the step of generating a speed control signal by performing speed closed-loop control based on the corresponding speed control command sequence, speed closed-loop control parameters, and injection piston position feedback signal specifically involves:

[0021] Construct a continuous speed target curve based on the speed control command sequence;

[0022] The current actual position of the injection piston is determined based on the feedback signal of the injection piston position.

[0023] Based on the current actual position, interpolation is performed on the continuous velocity target curve to obtain the target velocity corresponding to the current moment;

[0024] The current actual velocity of the injection piston is calculated based on the actual positions of the two most recently acquired adjacent injection pistons and the preset time interval.

[0025] The target speed is compared with the current actual speed to obtain the speed deviation;

[0026] Based on the speed deviation and the speed closed-loop control parameters, the speed control signal is generated through a closed-loop control algorithm.

[0027] Further, the step of generating a pressure control signal by performing pressure closed-loop control based on the pressure control command sequence, pressure closed-loop control parameters, and pressure feedback signal corresponding to the injection shaft includes:

[0028] A continuous pressure target curve is constructed based on the pressure control command sequence;

[0029] Based on the system time of the current control cycle, time interpolation is performed on the continuous pressure target curve to obtain the target pressure value corresponding to the current moment;

[0030] The current actual pressure is determined based on the pressure feedback signal;

[0031] The target pressure value is compared with the current actual pressure to obtain the pressure deviation;

[0032] The pressure control signal is generated based on the pressure deviation and the pressure closed-loop control parameters through a closed-loop control algorithm.

[0033] Furthermore, for each injection shaft, the corresponding speed servo valve module includes:

[0034] A first servo valve is provided at the oil inlet of the injection cylinder on the injection shaft, a second servo valve is provided at the oil return port of the injection cylinder on the injection shaft, and a first servo valve amplifier and a second servo valve amplifier are electrically connected to the first servo valve and the second servo valve respectively.

[0035] Furthermore, during the execution of speed closed-loop control:

[0036] When the current target speed is less than the preset high-speed threshold, the second core outputs the speed control signal and a shut-off signal to the analog output module; the analog output module outputs the speed control signal to the first servo valve amplifier to drive the first servo valve to operate, and outputs the shut-off signal to the second servo valve amplifier to shut off the second servo valve;

[0037] When the current target speed is greater than or equal to the high-speed threshold, the second core outputs the speed control signal and the second control signal to the analog output module, wherein the second control signal is calculated based on the amplitude of the speed control signal and a preset proportional coefficient; the analog output module outputs the speed control signal to the first servo valve amplifier to drive the first servo valve to operate, and outputs the second control signal to the second servo valve amplifier to drive the second servo valve to operate, so that the opening degree of the first servo valve and the second servo valve maintains a preset proportional relationship.

[0038] Furthermore, the analog output module is used to convert the speed control signal or pressure control signal into a corresponding analog control signal and output it to the corresponding speed servo valve module or pressure boosting servo valve module; wherein, the analog control signal is a voltage signal or a current signal.

[0039] Compared with the prior art, the present invention has at least the following beneficial effects:

[0040] (1) The present invention employs a processor comprising a first core for logic processing and a second core for real-time motion control. The first core receives motion commands from the die-casting machine controller, parses them to obtain the speed control command sequence and pressure control command sequence of the corresponding injection shaft, and encapsulates them with the corresponding speed closed-loop control parameters and pressure closed-loop control parameters to form motion data blocks, which are then sent to the second core. The second core executes speed closed-loop control and pressure closed-loop control within a preset control cycle based on the motion data blocks, and outputs the generated speed or pressure control signal to the corresponding speed servo valve module via the analog output module. Alternatively, a booster servo valve module can be used to achieve resource isolation and timing decoupling between logic processing tasks and real-time motion control tasks within the processor. As a result, the second core does not need to respond to non-real-time task interference and can stably run the closed-loop control algorithm with a fixed and deterministic cycle. This ensures that the control signal output by the analog output module has strict time determinism and high response consistency, fundamentally eliminating defects such as control cycle drift, execution delay, or control signal jitter caused by logic processing and real-time motion control sharing the same processing resources. This significantly improves the real-time performance and reliability of the die-casting machine control system during high-speed injection and booster switching processes.

[0041] (2) In this invention, the second core determines whether the preset pressure triggering condition is met based on the position feedback signal of the injection piston, and switches between speed closed-loop control and pressure closed-loop control accordingly: when the pressure triggering condition is not met, the speed control signal is output to the speed servo valve module; when the pressure triggering condition is met, the pressure control signal is output to the pressure servo valve module, thereby realizing the automatic control mode switching based on real-time position feedback.

[0042] (3) The present invention collects the position feedback signal of the injection piston through the signal input module and the pressure feedback signal of the booster cylinder through the analog input module, and uses them for speed closed-loop control and pressure closed-loop control respectively. That is, the control output is dynamically adjusted through real-time feedback, which improves the control accuracy of the injection piston movement speed and booster cylinder pressure.

[0043] (4) In the speed closed-loop control, the second core constructs a continuous speed target curve based on the speed control command sequence, and interpolates the target speed on the curve according to the current actual position of the injection piston. Combined with the actual speed calculated by the position feedback, a speed deviation is generated, and then a speed control signal is output. In the pressure closed-loop control, a continuous pressure target curve is constructed based on the pressure control command sequence, and the current target pressure value is obtained according to the system time interpolation. Combined with the pressure feedback signal, a pressure deviation is generated, and then a pressure control signal is output, thereby realizing high-fidelity tracking of complex injection process trajectories. Attached Figure Description

[0044] Figure 1 This is a schematic diagram of the structure of the hydraulic shaft controller according to an embodiment of the present invention;

[0045] Figure 2 This is a schematic diagram of the communication structure between the injection shaft and the hydraulic shaft controller in an embodiment of the present invention. Detailed Implementation

[0046] The following are specific embodiments of the present invention, which are described in conjunction with the accompanying drawings to further illustrate the technical solutions of the present invention. However, the present invention is not limited to these embodiments.

[0047] To overcome the problems of slow response, insufficient control accuracy, and poor real-time performance in traditional die-casting machine hydraulic systems during high-speed injection and rapid pressurization switching, and to fully leverage the dynamic performance advantages of high-frequency response proportional servo valves, this invention proposes a die-casting machine injection control method based on a hydraulic shaft controller. The die-casting machine includes one or more injection shafts; the hydraulic shaft controller includes a processor (specifically an ARM processor) and an analog output module; the processor includes a first core for logic processing and a second core for real-time motion control.

[0048] Specifically, such as Figure 1 As shown, the hydraulic shaft controller further includes:

[0049] The EtherCAT slave (i.e., a communication interface module based on the EtherCAT industrial Ethernet protocol) is used to realize real-time communication between the die-casting machine controller and the first core.

[0050] The data storage unit is used to store motion data blocks parsed by the first kernel and sent to the second kernel.

[0051] A power-loss protected memory is used to save the motion data block when power is off;

[0052] The information exchange module is used to connect to the human-machine interface or local operating device;

[0053] The power supply module is used to receive external power input and provide operating power to the processor, analog input module, analog output module, signal input module, EtherCAT slave, data memory, power-down protection memory, and information exchange module.

[0054] In this embodiment, the analog output module is a multi-channel structure with multiple independent digital-to-analog conversion channels, which can provide control signals to multiple speed servo valve modules and multiple booster servo valve modules; the analog input module is also a multi-channel structure with multiple independent analog-to-digital conversion channels, which are used to collect the pressure feedback signals of the booster cylinders of each injection shaft.

[0055] In addition, such as Figure 2 As shown, the injection shaft in this embodiment includes an injection cylinder, a booster cylinder, a position gauge, a pressure sensor, a speed servo valve module, and a booster servo valve module. The position gauge is connected to the injection piston rod via mechanical linkage or a non-contact method to detect the axial displacement position of the injection piston in real time and outputs the position signal to the signal input module. The pressure sensor is installed on the hydraulic chamber of the booster cylinder to detect the oil pressure within the booster chamber and outputs the pressure signal to the analog input module.

[0056] The method includes:

[0057] The first core receives motion commands from the die-casting machine controller, corresponding to each injection axis. For each motion command:

[0058] The motion commands include speed command data blocks and boost command data blocks.

[0059] The motion command is parsed to obtain the speed control command sequence and pressure control command sequence of the corresponding injection axis; the speed control command sequence, pressure control command sequence, speed closed-loop control parameters and pressure closed-loop control parameters are combined and encapsulated into a motion data block and sent to the second kernel;

[0060] In this invention, the speed closed-loop control parameters include, but are not limited to: proportional gain, integral time, derivative time, and maximum allowable acceleration;

[0061] The pressure closed-loop control parameters include, but are not limited to: proportional gain, integral time, derivative time, and maximum allowable pressure change rate (i.e., the upper limit of the pressure rise / fall slope).

[0062] The above parameters can be configured by the die-casting machine controller when issuing motion commands, or pre-stored in the non-volatile memory of the hydraulic shaft controller. Figure 1 (Not shown) is used by the second kernel to construct the target curve and execute closed-loop control. The non-volatile memory also stores a preset high-speed threshold.

[0063] To clearly illustrate the data structure of the speed control command sequence and the pressure control command sequence, this embodiment shows their components in list form:

[0064] Table 1: Speed ​​Control Command Sequence

[0065]

[0066] Table 2: Pressure Control Command Sequence

[0067]

[0068] Wherein, P1 to Pn represent multiple preset position parameters of the injection piston during the injection stroke, V1 to Vn are the speed parameters expected to be reached at the corresponding positions, and A1 to An are the corresponding acceleration parameters; T1 to Tn represent multiple time parameters starting from the beginning of the pressurization stage, and they increase sequentially in chronological order, and Q1 to Qn are the pressure parameters to be applied at the corresponding times.

[0069] In Table 1, the “serial number” indicates the execution order of the speed control data items during the injection stroke: serial number 1 corresponds to the first control point near the zero-return starting position, serial number n corresponds to the last control point near the mold cavity, and each serial number is arranged sequentially according to the actual path of the injection piston moving from the zero-return starting position towards the mold cavity.

[0070] In Table 2, the “serial number” indicates the execution order of the pressure control data items, which is consistent with the order of the time parameters.

[0071] Where n is a positive integer, representing the number of data items in each instruction sequence.

[0072] The process of parsing the motion command yields the corresponding speed control command sequence and pressure control command sequence for the injection axis, including:

[0073] The speed command data block is parsed to extract multiple position parameters, speed parameters corresponding to each position parameter, and acceleration parameters corresponding to each position parameter. The position parameters, corresponding speed parameters, and corresponding acceleration parameters are grouped into multiple data items according to their one-to-one correspondence, and the multiple data items are arranged in the order of the injection stroke to form a speed control command sequence.

[0074] In this embodiment, the data items are arranged in the order of the injection stroke, which means that they are sorted sequentially according to the physical path of the injection piston moving from the zero-return starting position towards the mold cavity.

[0075] The pressurization command data block is parsed to extract multiple time parameters and pressure parameters that correspond one-to-one with each time parameter; the time parameters and the corresponding pressure parameters are grouped into multiple data items according to their one-to-one correspondence, and the multiple data items are arranged in chronological order to form a pressure control command sequence.

[0076] The hydraulic shaft controller also includes:

[0077] The analog input module is used to acquire the pressure feedback signal of the booster cylinder of each injection shaft and provide the pressure feedback signal to the second core for pressure closed-loop control;

[0078] The signal input module is used to collect the injection piston position feedback signal of each injection axis and provide the injection piston position feedback signal to the second core for speed closed-loop control.

[0079] This invention acquires the position feedback signal of the injection piston through a signal input module and the pressure feedback signal of the booster cylinder through an analog input module, and uses them for speed closed-loop control and pressure closed-loop control, respectively. That is, the control output is dynamically adjusted through real-time feedback, which improves the control accuracy of the injection piston movement speed and booster cylinder pressure.

[0080] Through the second core, based on the motion data block corresponding to each injection axis, speed closed-loop control and pressure closed-loop control are performed on the corresponding injection axis within a preset control cycle. According to the type of closed-loop control currently being performed, the corresponding control signal is output to the speed servo valve module or pressure boosting servo valve module of the corresponding injection axis via the analog output module to adjust the speed of the injection piston or the pressure of the boosting cylinder.

[0081] In this embodiment, the speed servo valve module is used to adjust the flow rate of hydraulic oil entering the injection cylinder according to the speed control signal, thereby controlling the movement speed of the injection piston; the pressure boosting servo valve module is used to adjust the hydraulic pressure of the pressure boosting chamber according to the pressure control signal during the pressure boosting stage, so as to achieve and maintain the set pressure boosting pressure.

[0082] The process involves using a second core to perform speed closed-loop control and pressure closed-loop control on the corresponding injection axis within a preset control cycle, based on the motion data block corresponding to each injection axis. Depending on the currently executed closed-loop control type, a corresponding control signal is output via an analog output module to the speed servo valve module or pressure boosting servo valve module of the corresponding injection axis.

[0083] For each injection axis:

[0084] Based on its corresponding speed control command sequence, speed closed-loop control parameters and its injection piston position feedback signal, speed closed-loop control is executed to generate speed control signal, which is then output to the speed servo valve module corresponding to the injection shaft via the analog output module.

[0085] The process of generating a speed control signal by performing speed closed-loop control based on the corresponding speed control command sequence, speed closed-loop control parameters, and injection piston position feedback signal is as follows:

[0086] Construct a continuous speed target curve based on the speed control command sequence;

[0087] In this embodiment, the second kernel processes the speed control command sequence to construct a continuous speed target curve. This speed control command sequence consists of multiple data items arranged in the order of the injection stroke. Each data item includes a position parameter, a corresponding speed parameter, and a corresponding acceleration parameter. Based on each data item in the speed control command sequence, the second kernel utilizes the correspondence between the position, speed, and acceleration parameters to construct a continuous speed target curve. Specifically, the second kernel generates a transition segment between every two adjacent positions based on the position, speed, and acceleration parameters in adjacent data items, ensuring continuous speed variation along the stroke and no abrupt acceleration changes. In other words, the speed change between adjacent positions is smooth, and the acceleration transitions smoothly, effectively avoiding hydraulic shocks and servo valve oscillations caused by sudden changes in motion. The resulting continuous speed target curve serves as the input reference for speed closed-loop control, driving the servo valve to ensure smooth injection piston movement and controllable filling process.

[0088] Specifically, the methods for constructing the continuous velocity target curve include, but are not limited to:

[0089] (1) Using the position, velocity, and acceleration of two adjacent data items as boundary conditions, a smooth trajectory is generated by fitting a fifth-order polynomial;

[0090] (2) Use S-shaped acceleration and deceleration (such as a seven-segment acceleration profile) to make the acceleration change continuously and ensure that the velocity and position are continuously differentiable;

[0091] (3) When the acceleration of two adjacent data items is zero, a cubic polynomial or uniform acceleration model can be used to generate the transition segment.

[0092] The calculation of the target velocity does not depend on linear interpolation of the velocity parameters, but is solved in real time based on the kinematic relationship of the constructed curve.

[0093] The current actual position of the injection piston is determined based on the feedback signal of the injection piston position.

[0094] It should be noted that before the closed-loop control begins, the die-casting machine has completed the mold closing action and the zeroing operation of the injection piston. At this time, the position gauge (such as a magnetostrictive displacement sensor or a linear displacement sensor) mounted on the injection shaft is in normal working condition and outputs a valid start position signal to the second core through the signal input module. Therefore, during the execution of speed closed-loop control, the second core can continuously acquire the real-time position feedback signal of the injection piston for the purpose of obtaining the target speed.

[0095] Based on the current actual position, interpolation is performed on the continuous velocity target curve to obtain the target velocity corresponding to the current moment;

[0096] The current actual velocity of the injection piston is calculated based on the actual positions of the two most recently acquired adjacent injection pistons and the preset time interval.

[0097] In this embodiment, the second kernel performs control operations according to a preset control cycle, which corresponds to a fixed time interval (e.g., 1 millisecond) pre-set by the system. Within each control cycle, the signal input module obtains the position feedback signal of the injection piston from the position ruler of the injection shaft and determines the current actual position of the injection piston based on this signal. Simultaneously, the second kernel reads the actual position of the injection piston stored in the previous control cycle, thereby obtaining the actual positions of the injection piston within two consecutive adjacent control cycles. Based on these two adjacent positions and the preset time interval, the current actual speed of the injection piston is calculated in real time. Since the time interval is a known and constant system parameter, the speed calculation only depends on the change between two adjacent actual positions, eliminating the need for additional speed sensors and achieving highly responsive real-time speed feedback.

[0098] The target speed is compared with the current actual speed to obtain the speed deviation;

[0099] Based on the speed deviation and the speed closed-loop control parameters, the speed control signal is generated by a closed-loop control algorithm (e.g., PID algorithm).

[0100] For each injection axis, the corresponding speed servo valve module includes:

[0101] A first servo valve is provided at the oil inlet of the injection cylinder on the injection shaft, a second servo valve is provided at the oil return port of the injection cylinder on the injection shaft, and a first servo valve amplifier and a second servo valve amplifier are electrically connected to the first servo valve and the second servo valve respectively.

[0102] During the execution of speed closed-loop control:

[0103] When the current target speed is less than the preset high-speed threshold, the second core outputs the speed control signal and a shut-off signal to the analog output module; the analog output module outputs the speed control signal to the first servo valve amplifier to drive the first servo valve to operate, and outputs the shut-off signal to the second servo valve amplifier to shut off the second servo valve;

[0104] In this embodiment, the closing signal output by the analog output module refers to the analog signal that makes the servo valve close, which is usually 0mA or a bias current lower than the valve core opening threshold.

[0105] When the current target speed is greater than or equal to the high-speed threshold, the second core outputs the speed control signal and the second control signal to the analog output module, wherein the second control signal is calculated based on the amplitude of the speed control signal and a preset proportional coefficient; the analog output module outputs the speed control signal to the first servo valve amplifier to drive the first servo valve to operate, and outputs the second control signal to the second servo valve amplifier to drive the second servo valve to operate, so that the opening degree of the first servo valve and the second servo valve maintains a preset proportional relationship.

[0106] When the position feedback signal of the injection piston of the injection shaft meets the preset pressure boosting trigger condition (that is, when the actual position of the injection piston reaches the preset pressure boosting start position), pressure closed-loop control is executed to generate a pressure control signal according to the pressure control command sequence, pressure closed-loop control parameters and pressure feedback signal corresponding to the injection shaft, and then output to the pressure boosting servo valve module corresponding to the injection shaft through the analog output module.

[0107] In this invention, the second core determines whether the preset pressure triggering condition is met based on the position feedback signal of the injection piston, and switches between speed closed-loop control and pressure closed-loop control accordingly: when the pressure triggering condition is not met, a speed control signal is output to the speed servo valve module; when the pressure triggering condition is met, a pressure control signal is output to the pressure servo valve module, thereby realizing automatic control mode switching based on real-time position feedback.

[0108] The step of generating a pressure control signal by performing pressure closed-loop control based on the pressure control command sequence, pressure closed-loop control parameters, and pressure feedback signal corresponding to the injection shaft includes:

[0109] A continuous pressure target curve is constructed based on the pressure control command sequence;

[0110] Specifically, the methods for constructing the continuous pressure target curve include, but are not limited to:

[0111] (1) Using the pressure value and time parameter of two adjacent data items as endpoint conditions, combined with the preset pressure change rate constraint (such as the maximum pressure rise / fall slope), cubic spline interpolation, fifth polynomial fitting or S-shaped function are used to generate a smooth transition segment;

[0112] (2) Adopt an S-shaped pressure ramp strategy (e.g., a seven-segment pressure change profile) to make the pressure change rate change continuously, thereby avoiding hydraulic shock or servo valve oscillation caused by sudden pressure changes.

[0113] (3) When the time interval between two adjacent data items is short and the pressure difference is small, a linear gradual change section or a constant pressure section can be used for connection.

[0114] The calculation of the target pressure does not rely on simple linear interpolation of the pressure parameters, but is solved in real time based on the time-pressure function relationship of the constructed continuous pressure target curve, ensuring the stability and response accuracy of the pressure closed-loop control.

[0115] Based on the system time of the current control cycle, time interpolation is performed on the continuous pressure target curve to obtain the target pressure value corresponding to the current moment;

[0116] The current actual pressure is determined based on the pressure feedback signal;

[0117] The target pressure value is compared with the current actual pressure to obtain the pressure deviation;

[0118] Based on the pressure deviation and the pressure closed-loop control parameters, the pressure control signal is generated by a closed-loop control algorithm (e.g., PID algorithm).

[0119] In this embodiment, the second core transmits the received injection piston position feedback signal, the pressure feedback signal from the booster cylinder, and the current actual velocity of the injection piston calculated based on the injection piston position feedback signal to the first core; the first core transmits the above information (i.e. Figure 2 The feedback signal is uploaded to the die-casting machine controller.

[0120] In the speed closed-loop control, the second core constructs a continuous speed target curve based on the speed control command sequence, and interpolates the target speed on the curve according to the current actual position of the injection piston. Combined with the actual speed calculated by position feedback, a speed deviation is generated, and then a speed control signal is output. In the pressure closed-loop control, a continuous pressure target curve is constructed based on the pressure control command sequence, and the current target pressure value is obtained by interpolating the system time. Combined with the pressure feedback signal, a pressure deviation is generated, and then a pressure control signal is output, thereby achieving high-fidelity tracking of complex injection process trajectories.

[0121] The analog output module is used to convert the speed control signal or pressure control signal into a corresponding analog control signal and output it to the corresponding speed servo valve module or pressure boosting servo valve module; wherein, the analog control signal is a voltage signal or a current signal.

[0122] In this embodiment, the speed control signal refers to a digital control command generated by the second core for adjusting the speed of the injection piston. This speed control signal is represented digitally in the second core (e.g., a 16-bit signed integer) and sent to the analog output module. The analog output module performs a D / A conversion on the digital signal, outputting a corresponding analog voltage signal (e.g., ±10V) or current signal (e.g., 4–20mA) to the speed servo valve module of the corresponding injection axis to drive the servo valve to adjust the hydraulic flow, thereby controlling the speed of the injection piston. Although this signal undergoes a conversion from digital to analog during transmission, its control function remains consistent; therefore, it is collectively referred to as the speed control signal.

[0123] Similarly, the pressure control signal refers to the digital control command generated by the second core for adjusting the pressure of the booster cylinder. This pressure control signal is represented digitally in the second core (e.g., a 16-bit signed integer) and sent to the analog output module. The analog output module performs a D / A conversion on the digital signal, outputting a corresponding analog voltage signal (e.g., ±10V) or current signal (e.g., 4–20mA) to the booster servo valve module used to control the booster process of the injection shaft, thereby driving the servo valve to adjust the hydraulic pressure in the booster chamber and thus controlling the booster process of the injection system. Although this signal undergoes a conversion from digital to analog during transmission, its control function remains consistent, and therefore it is collectively referred to as a pressure control signal.

[0124] In this embodiment, the booster servo valve module includes a booster servo valve and its corresponding servo valve amplifier. The servo valve amplifier receives analog voltage or current signals from the analog output module and converts them into drive current to control the valve core displacement of the booster servo valve, thereby adjusting the hydraulic pressure of the booster chamber.

[0125] This invention employs a processor comprising a first core for logic processing and a second core for real-time motion control. The first core receives motion commands from the die-casting machine controller, parses them to obtain the speed control command sequence and pressure control command sequence corresponding to the injection axis, and combines them with the corresponding speed closed-loop control parameters and pressure closed-loop control parameters to encapsulate them into motion data blocks before sending them to the second core. Based on these motion data blocks, the second core executes speed closed-loop control and pressure closed-loop control within a preset control cycle, and outputs the generated speed or pressure control signals to the corresponding speed servo valve module or pressure boosting servo valve module via an analog output module. This achieves resource isolation and timing decoupling between logic processing tasks and real-time motion control tasks within the processor. Consequently, the second core does not need to respond to non-real-time task interference and can stably run the closed-loop control algorithm at a fixed and deterministic cycle, ensuring that the control signals output by the analog output module have strict time determinism and high response consistency. This fundamentally eliminates defects such as control cycle drift, execution delay, or control signal jitter caused by logic processing and real-time motion control sharing the same processing resources, significantly improving the real-time performance and reliability of the die-casting machine control system during high-speed injection and pressure boosting switching.

[0126] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indication will also change accordingly.

[0127] Furthermore, in this invention, descriptions involving terms such as "first," "second," and "a" are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0128] In this invention, unless otherwise explicitly specified and limited, the terms "connection," "fixed," etc., should be interpreted broadly. For example, "fixed" can mean a fixed connection, a detachable connection, or an integral part; it can mean a mechanical connection or an electrical connection; it can mean a direct connection or an indirect connection through an intermediate medium; it can mean the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0129] Furthermore, the technical solutions of the various embodiments of the present invention can be combined with each other, but only if they are feasible for those skilled in the art. If the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

Claims

1. A hydraulic shaft controller-based injection control method for a die casting machine, characterized by, The die-casting machine includes one or more injection shafts; the hydraulic shaft controller includes a processor and an analog output module; the processor includes a first core for logic processing and a second core for real-time motion control; the method includes: The first core receives motion commands from the die-casting machine controller, corresponding to each injection axis. For each motion command: The motion command is parsed to obtain the speed control command sequence and pressure control command sequence of the corresponding injection axis; the speed control command sequence, pressure control command sequence, speed closed-loop control parameters and pressure closed-loop control parameters are combined and encapsulated into a motion data block and sent to the second kernel; Through the second core, based on the motion data block corresponding to each injection axis, speed closed-loop control and pressure closed-loop control are performed on the corresponding injection axis within a preset control cycle. According to the type of closed-loop control currently being performed, the corresponding control signal is output to the speed servo valve module or pressure boosting servo valve module of the corresponding injection axis via the analog output module to adjust the speed of the injection piston or the pressure of the boosting cylinder.

2. The injection control method for a die-casting machine based on a hydraulic shaft controller according to claim 1, characterized in that, The process involves using a second core to perform speed closed-loop control and pressure closed-loop control on the corresponding injection axis within a preset control cycle, based on the motion data block corresponding to each injection axis. Depending on the currently executed closed-loop control type, a corresponding control signal is output via an analog output module to the speed servo valve module or pressure boosting servo valve module of the corresponding injection axis. For each injection axis: Based on its corresponding speed control command sequence, speed closed-loop control parameters and its injection piston position feedback signal, speed closed-loop control is executed to generate speed control signal, which is then output to the speed servo valve module corresponding to the injection shaft via the analog output module. When the position feedback signal of the injection piston of the injection shaft meets the preset pressure boosting trigger condition, pressure closed-loop control is executed to generate a pressure control signal according to the pressure control command sequence, pressure closed-loop control parameters and pressure feedback signal corresponding to the injection shaft, and then output to the pressure boosting servo valve module corresponding to the injection shaft through the analog output module.

3. The injection control method for a die-casting machine based on a hydraulic shaft controller according to claim 2, characterized in that, The motion commands include speed command data blocks and boost command data blocks.

4. The injection control method for a die-casting machine based on a hydraulic shaft controller according to claim 3, characterized in that, The process of parsing the motion command yields the corresponding speed control command sequence and pressure control command sequence for the injection axis, including: The speed command data block is parsed to extract multiple position parameters, speed parameters corresponding to each position parameter, and acceleration parameters corresponding to each position parameter. The position parameters, corresponding speed parameters, and corresponding acceleration parameters are grouped into multiple data items according to their one-to-one correspondence, and the multiple data items are arranged in the order of the injection stroke to form a speed control command sequence. The pressurization command data block is parsed to extract multiple time parameters and pressure parameters that correspond one-to-one with each time parameter; the time parameters and the corresponding pressure parameters are grouped into multiple data items according to their one-to-one correspondence, and the multiple data items are arranged in chronological order to form a pressure control command sequence.

5. The injection control method for a die-casting machine based on a hydraulic shaft controller according to claim 4, characterized in that, The hydraulic shaft controller also includes: The analog input module is used to acquire the pressure feedback signal of the booster cylinder of each injection shaft and provide the pressure feedback signal to the second core for pressure closed-loop control; The signal input module is used to collect the injection piston position feedback signal of each injection axis and provide the injection piston position feedback signal to the second core for speed closed-loop control.

6. The injection control method for a die-casting machine based on a hydraulic shaft controller according to claim 5, characterized in that, The process of generating a speed control signal by performing speed closed-loop control based on the corresponding speed control command sequence, speed closed-loop control parameters, and injection piston position feedback signal is as follows: Construct a continuous speed target curve based on the speed control command sequence; The current actual position of the injection piston is determined based on the feedback signal of the injection piston position. Based on the current actual position, interpolation is performed on the continuous velocity target curve to obtain the target velocity corresponding to the current moment; The current actual velocity of the injection piston is calculated based on the actual positions of the two most recently acquired adjacent injection pistons and the preset time interval. The target speed is compared with the current actual speed to obtain the speed deviation; Based on the speed deviation and the speed closed-loop control parameters, the speed control signal is generated through a closed-loop control algorithm.

7. The injection control method for a die-casting machine based on a hydraulic shaft controller according to claim 5, characterized in that, The step of generating a pressure control signal by performing pressure closed-loop control based on the pressure control command sequence, pressure closed-loop control parameters, and pressure feedback signal corresponding to the injection shaft includes: A continuous pressure target curve is constructed based on the pressure control command sequence; Based on the system time of the current control cycle, time interpolation is performed on the continuous pressure target curve to obtain the target pressure value corresponding to the current moment; The current actual pressure is determined based on the pressure feedback signal; The target pressure value is compared with the current actual pressure to obtain the pressure deviation; The pressure control signal is generated based on the pressure deviation and the pressure closed-loop control parameters through a closed-loop control algorithm.

8. The injection control method for a die-casting machine based on a hydraulic shaft controller according to claim 6, characterized in that, For each injection axis, the corresponding speed servo valve module includes: A first servo valve is provided at the oil inlet of the injection cylinder on the injection shaft, a second servo valve is provided at the oil return port of the injection cylinder on the injection shaft, and a first servo valve amplifier and a second servo valve amplifier are electrically connected to the first servo valve and the second servo valve respectively.

9. The injection control method for a die-casting machine based on a hydraulic shaft controller according to claim 8, characterized in that, During the execution of speed closed-loop control: When the current target speed is less than the preset high-speed threshold, the second core outputs the speed control signal and a shut-off signal to the analog output module; the analog output module outputs the speed control signal to the first servo valve amplifier to drive the first servo valve to operate, and outputs the shut-off signal to the second servo valve amplifier to shut off the second servo valve; When the current target speed is greater than or equal to the high-speed threshold, the second core outputs the speed control signal and the second control signal to the analog output module, wherein the second control signal is calculated based on the amplitude of the speed control signal and a preset proportional coefficient; the analog output module outputs the speed control signal to the first servo valve amplifier to drive the first servo valve to operate, and outputs the second control signal to the second servo valve amplifier to drive the second servo valve to operate, so that the opening degree of the first servo valve and the second servo valve maintains a preset proportional relationship.

10. The injection control method for a die-casting machine based on a hydraulic shaft controller according to claim 2, characterized in that, The analog output module is used to convert the speed control signal or pressure control signal into a corresponding analog control signal and output it to the corresponding speed servo valve module or pressure boosting servo valve module; wherein, the analog control signal is a voltage signal or a current signal.

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