Intelligent hydraulic mode locking mechanism based on magnetorheological effect and mode locking compensation method

Abstract

The invention relates to the technical field of hydraulic mechanical mold locking, in particular to an intelligent hydraulic mold locking mechanism based on the magnetorheological effect and a mold locking compensation method.The intelligent hydraulic mold locking mechanism comprises a fixed mold plate, a movable mold plate, a tail mold plate and a guide threaded pull rod, and a magnetorheological fluid bearing flange is installed between a mold locking hydraulic cylinder fixed to the tail mold plate and the movable mold plate; a connecting base plate is arranged between the flange connecting concave plate and the movable mold plate, four pressure sensors are arranged between the connecting base plate and the movable mold plate, a cavity between the flange connecting convex plate and the flange connecting concave plate is a closed containing cavity, a permanent magnet is installed in the flange connecting convex plate in an embedded mode, and an electromagnetic coil is installed in the flange connecting concave plate in an embedded mode. The closed containing cavity is filled with magnetorheological fluid. According to the invention, the dynamic adjustment response speed of the mold locking force and the anti-unbalance loading forming precision are improved, the size is continuous and controllable, the mold locking force fluctuation caused by slow continuous or intermittent pressure maintaining response of the mold locking hydraulic cylinder is avoided, the viscosity of the magnetorheological fluid is changed by trace electromagnetic pulses to establish the compensation self-adaptive mold locking force, and the comprehensive energy consumption is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of hydraulic mechanical mold clamping, and particularly to an intelligent hydraulic mold clamping mechanism and a mold clamping compensation method based on the magnetorheological effect. Background Art

[0002] Injection molding machines and die-casting machines are mechanical devices that inject molten materials into the mold cavity under high pressure through mold clamping, and eject the products after pressure holding and cooling and shaping. Among them, during the mold clamping and pressure holding processes, a mold clamping force needs to be continuously provided to resist the mold expansion force to ensure the forming accuracy. Hydraulic mold clamping and pressure compensation is to continuously or intermittently supplement the pressure through a hydraulic system to ensure that the mold clamping force always reaches the set value when the mold is closed. Among them, the non-uniform load during the injection filling process is likely to cause an eccentric load effect, resulting in local fluctuations in the mold clamping force, generating flash or mold expansion defects. At the same time, a pressure sensor is used to feedback and adjust the oil pressure, and the response of the hydraulic system is slow (about 200 - 500 ms), and it cannot quickly compensate for the dynamic mold cavity pressure change. Summary of the Invention

[0003] In order to solve the problems existing in the above-mentioned prior art, the present invention provides an intelligent hydraulic mold clamping mechanism and a mold clamping compensation method based on the magnetorheological effect.

[0004] On the one hand, an intelligent hydraulic mold clamping mechanism based on the magnetorheological effect provided by the present invention adopts the following technical solutions: An intelligent hydraulic mold clamping mechanism based on the magnetorheological effect includes a fixed template, a moving template, a tail template, and a guiding threaded tie rod. The fixed template, the moving template, and the tail template are all installed on the guiding threaded tie rod. A mold clamping hydraulic cylinder is fixed on the tail template, and a magnetorheological fluid bearing flange is installed between the mold clamping hydraulic cylinder and the moving template. The magnetorheological fluid bearing flange includes a flange connecting convex plate and a flange connecting concave plate. The flange connecting convex plate is connected to the push rod of the mold clamping hydraulic cylinder. A connecting cushion plate is arranged between the flange connecting concave plate and the moving template. Four pressure sensors are arranged between the connecting cushion plate and the moving template, and the four pressure sensors are respectively installed at the four corners of the connecting cushion plate. The flange connecting convex plate and the flange connecting concave plate are buckled and fixed. The cavity between the flange connecting convex plate and the flange connecting concave plate is a closed cavity. A sealing ring for sealing the closed cavity is arranged on the flange connecting concave plate. A permanent magnet is embedded in the flange connecting convex plate, and an electromagnetic coil winding is embedded in the flange connecting concave plate as an exciting body. The closed cavity is filled with magnetorheological fluid.

[0005] Optionally, the magnetorheological fluid is a silicone oil-based magnetorheological fluid containing iron oxide nanoparticles.

[0006] Optionally, there are 16 permanent magnets, which are divided into two inner and outer circles and evenly arranged along the circumferential direction of the flange connecting convex plate. There are also 16 electromagnetic coil windings, which are divided into two inner and outer circles and evenly arranged along the circumferential direction of the flange connecting concave plate. The permanent magnets correspond to the electromagnetic coil windings one by one.

[0007] On the other hand, the present invention also discloses an intelligent hydraulic mold clamping compensation method based on the magnetorheological effect, which includes the following steps: S1. The mold clamping hydraulic cylinder pushes the moving template to complete mold closing and shuts down the driving hydraulic pump, and the closed-loop feedback control system is started. S2. The pressure sensors at the four corners of the connecting cushion plate detect the pressure set value and distribution deviation of the connecting cushion plate. The electromagnetic coil windings are connected to a pulsed current to generate a variable magnetic field, which is superimposed on the basic magnetic field provided by the permanent magnets and acts on the magnetorheological fluid, so that the magnetorheological fluid maintains a set semi-cured state.

[0008] S3. When the pressure loss or deviation feedback by the pressure sensor exceeds the set threshold, the PID controller calculates the current adjustment amount and outputs a control signal to the current controller to execute the adjustment of the electromagnetic coil winding current change.

[0009] S4. The combined magnetic field changes the viscosity of the local magnetorheological fluid at the corresponding position. The pressure sensor detects and updates the feedback pressure and deviation threshold change in real time. When the design requirements are met, the coil current stops adjusting.

[0010] Compared with the prior art, the present invention has the following technical effects: The present invention uses the injection molding machine mold clamping mechanism to add a magnetorheological fluid bearing flange mechanism, reducing the setting and maintenance requirements of complex structures such as continuous or intermittent pressure compensation electro-control valves and mechanical devices of the mold clamping cylinder required for high precision and fast response. After mold closing, a magnetorheological fluid mold clamping compensation pressure is established through the closed-loop feedback of the pressure sensor, and the mold clamping force is locally dynamically and precisely compensated with a micro current. It is an energy-efficient and maintenance-free hydraulic mold clamping compensation method without mechanical wear. Description of the Drawings

[0011] Figure 1 It is a schematic diagram of the mold clamping mechanism provided by the embodiment of the present invention; Figure 2 It is a schematic diagram of the magnetorheological fluid bearing flange mechanism provided by the embodiment of the present invention; Figure 3 It is a schematic diagram of the electromagnetic coil distribution provided by the embodiment of the present invention; Figure 4 It is a schematic diagram of the pressure sensor installation provided by the embodiment of the present invention; Figure 5 It is a schematic diagram of the installation of the moving template and the magnetorheological fluid bearing flange mechanism provided by the embodiment of the present invention; Figure 6This is the intelligent mold clamping control flow chart provided by the embodiments of the present invention.

[0012] Description of reference numerals: 1, fixed platen; 2, moving platen; 3, tail platen; 4, guiding threaded tie rod; 5, mold clamping hydraulic cylinder; 6, flange connection convex plate; 7, flange connection concave plate; 8, sealing ring; 9, permanent magnet; 10, electromagnetic coil winding; 11, magnetorheological fluid; 12, connecting backing plate; 13, pressure sensor. Specific embodiments

[0013] The following is a further detailed description of the present invention in conjunction with the attached Figure 1 - attached Figure 6 drawings.

[0014] The magnetorheological fluid is used as the dynamic adjustment medium for the mold clamping force. It is a magnetic soft particle suspension formed by mixing tiny soft magnetic particles with high magnetic permeability and low hysteresis and non-magnetic conductive liquid. This suspension shows low viscosity characteristics under zero magnetic field conditions, while showing high viscosity and low fluidity liquid characteristics under the action of a strong magnetic field.

[0015] Referring to Figures 1-6 , the embodiments of the present invention disclose an intelligent hydraulic mold clamping mechanism based on the magnetorheological effect, including a fixed platen 1, a moving platen 2 and a tail platen 3. The fixed platen 1, the moving platen 2 and the tail platen 3 are connected in series by guiding threaded tie rods 4 to form a three-beam and four-column mold clamping frame structure. Threads are provided at both ends of the guiding threaded tie rod 4, and the middle section is a smooth section. The moving platen 2 can slide along the smooth section. Fixed nuts are provided at both ends of the fixed platen 1, and the fixed nuts are threadedly connected to the guiding threaded tie rod 4, and the fixed nuts fix the position of the fixed platen 1. Similarly, the tail platen 3 is also fixed by a fixed nut.

[0016] A mold clamping hydraulic cylinder 5 is fixed on the tail platen 3. A magnetorheological fluid bearing flange is connected to the push rod of the mold clamping hydraulic cylinder 5. The push rod of the mold clamping hydraulic cylinder 5 is installed on the end face of the moving platen 2 through the magnetorheological fluid bearing flange. The push rod of the mold clamping hydraulic cylinder 5 pushes the moving platen 2 to move back and forth along the guiding threaded tie rod 4, so that the moving platen 2 opens and closes the mold. The fixed platen 1 is used as the injection port for reserving the injection channel.

[0017] The magnetorheological fluid bearing flange includes a flange connection convex plate 6 and a flange connection concave plate 7. The flange connection convex plate 6 and the flange connection concave plate 7 are buckled. A sealing ring 8 is arranged in the flange connection concave plate 7. The flange connection convex plate 6 and the flange concave plate form a closed cavity through the sealing ring 8. The closed cavity is an annular cavity, and the flange connection convex plate 6 and the flange connection concave plate 7 are fixed by bolts after being buckled. The flange connection convex plate 6 and the push rod of the mold clamping hydraulic cylinder 5 are fixed by bolts. A permanent magnet 9 is fixedly embedded in the flange connection convex plate 6. An electromagnetic coil winding 10 is fixedly installed in the flange connection concave plate 7 as an exciting body. The closed cavity is filled with a silicone oil-based magnetorheological fluid 11 containing iron tetroxide nanoparticles. The flange connection concave plate 7 symmetrically installs 16 electromagnetic coil windings 10 in two concentric circles around the center to provide a variable magnetic field, and 16 permanent magnets 9 are installed at the corresponding positions of the flange connection convex plate 6 to provide a basic magnetic field.

[0018] A connecting cushion plate 12 is installed between the magnetorheological fluid bearing flange and the moving template 2. The connecting cushion plate 12 is bolted to the moving template 2, and the connecting cushion plate 12 is fixed to the flange connection concave plate 7 by bolts.

[0019] Pressure sensors 13 are installed at the four corners of the connecting cushion plate 12 in a cross shape. Circular grooves are provided at the four corners of the connecting cushion plate 12. The pressure sensors 13 are located in the grooves. The detection ends of the pressure sensors 13 are in contact with the bottom of the grooves, and the other ends of the pressure sensors 13 are in contact with the moving template 2. During installation, first place the pressure sensors 13 into the grooves so that the detection ends of the pressure sensors 13 are in contact with the bottom of the grooves, and then fix the connecting cushion plate 12 to the moving template 2 by bolts. The surface of the connecting cushion plate 12 where the grooves are provided is in contact with the surface of the moving template 2.

[0020] The four pressure sensors 13 detect whether the connecting cushion plate 12 evenly transmits force to the moving template 2, and are used to judge whether the pressure is eccentric between the flange connection convex plate 6 and the flange connection concave plate 7, so as to adjust the magnetic field force.

[0021] A closed-loop feedback control system is established. Four groups of pressure sensors 13 are installed in a cross shape in the connecting cushion plate 12 between the magnetorheological fluid bearing flange and the moving template 2. Through the fuzzy PID control algorithm, a mathematical model of the clamping force deviation and the output current is established. According to the type of injection material, the initial PID parameters are preset to dynamically adjust the clamping force at different positions of the moving template 2 and optimize the control response.

[0022] The intelligent hydraulic clamping mechanism adopts a closed-loop feedback control system, four independent detection channels for the pressure sensors 13, a synchronous error calculation set value following algorithm, and a PID feedback adjustment control strategy and a safety protection mechanism. After the moving template 2 is closed and the clamping force fluctuation is stable, the hydraulic oil pump of the clamping cylinder is turned off, and the electromagnetic coil is switched to the pulse mode. The magnetorheological fluid 11 maintains a semi-solid state during the pulse interval, reducing the comprehensive energy consumption.

[0023] The present invention also discloses an intelligent hydraulic clamping compensation method based on the magnetorheological effect: S1. The clamping hydraulic cylinder 5 pushes the moving template 2 to complete the mold closing and closes the driving hydraulic pump, and the closed-loop feedback control system is started; S2. The pressure sensors 13 at the four corners of the connecting backing plate 12 detect the pressure set value and distribution deviation of the connecting backing plate 12. The electromagnetic coil winding 10 is connected to a pulsed current to generate a variable magnetic field, which acts on the magnetorheological fluid 11 in superposition with the basic magnetic field provided by the permanent magnet 9, so that the magnetorheological fluid 11 maintains a set semi-cured state.

[0024] S3. When the feedback pressure loss or deviation detected by the pressure sensors 13 exceeds the set threshold value, the PID controller calculates the current adjustment amount and outputs a control signal to the current controller to execute the adjustment of the current change of the electromagnetic coil winding 10.

[0025] For example, the four pressure sensors are the No. 1, 2, 3, and 4 sensors in sequence. If the pressure value of the No. 1 sensor is lower than the preset value and the pressure values of the No. 2, 3, and 4 pressure sensors are normal, the dynamic adjustment program is started. The No. 1 sensor feeds back the pressure variable to the controller, and the controller collects the real-time pressure values of the remaining No. 2, 3, and 4 pressure sensors; the controller adjusts the electromagnetic coil near the position of the No. 1 sensor to increase the output current, and the magnetic field strength is increased to increase the viscosity of the magnetorheological fluid, thereby increasing the support stiffness. The No. 1 pressure sensor monitors the pressure recovery change in real time and dynamically adjusts until the set value is reached. When the current of the electromagnetic coil near the No. 1 pressure sensor increases, the current of the electromagnetic coils near the No. 2, 3, and 4 pressure sensors should decrease, so as to maintain the basic viscosity of the magnetorheological fluid near the No. 2, 3, and 4 pressure sensors and avoid the residual magnetic field interfering with the system rebalancing. Continuously obtain the dynamic feedback of the pressure at the four corners of the connecting backing plate, and perform iterative optimization on the current output through the PID controller. When the standard deviation of the pressure at the four corners returns to the allowable error band, the system switches to the steady-state maintenance mode.

[0026] S4. The combined magnetic field changes the viscosity of the local magnetorheological fluid 11 at the corresponding position. The pressure sensors 13 detect and update the feedback pressure and deviation threshold change in real time. When the design requirements are met, the coil current stops adjusting.

[0027] The core component design provided by the present invention is a set of magnetorheological fluid-hydraulic composite intelligent clamping system. Compared with the clamping structure of the traditional injection molding machine, a dynamic adjustment flange with an annular cavity of magnetorheological fluid 11 is installed at the connection between the push rod of the clamping hydraulic cylinder 5 and the dynamic plate 2. The magnetorheological fluid 11 is filled into the annular cavity, the push rod flange on the upper end face of the cavity is embedded with a permanent magnet 9, and 16 groups of exciting coil windings are evenly arranged on the outer periphery of the lower end face, and the gradient magnetic field intensity is adjusted by changing the coil current. Under the action of the magnetic field, the rheological properties of the liquid are changed, and the flow resistance of the liquid is increased, so that before the clamping cylinder responds to the pressure compensation, a highly controllable compensation clamping force is quickly established. The clamping force is combined with the feedback signal of the pressure sensor 13 to realize a low-delay (about 50ms) dynamic response system, and the mold letting phenomenon caused by the compression of the hydraulic oil is eliminated by solidifying the magnetorheological fluid 11, thereby reducing the fluctuation and error of the clamping force. After the clamping force is stable, the electromagnetic coil is switched to the pulse mode, and the magnetorheological fluid 11 maintains a semi-solid state during the pulse interval to reduce the external input energy.

[0028] The hydraulic clamping method provided by the method can improve the dynamic adjustment response of the clamping force and the anti-eccentric load forming accuracy while reducing the complex structural conditions such as electromechanical control valves and mechanical devices. The size can be continuously controlled to avoid the clamping force fluctuation caused by the slow response of the continuous or intermittent pressure holding of the clamping hydraulic cylinder 5. The viscosity of the magnetorheological fluid 11 is changed by a trace electromagnetic pulse to establish a compensating adaptive clamping force, thereby reducing the overall energy consumption. It is an energy-saving, efficient and maintenance-free hydraulic clamping compensation method.

[0029] The intelligent hydraulic clamping method based on magnetorheological effect provided by the method can produce asymmetric eccentric load when the injection liquid is unevenly filled along the flow channel during the mold closing and injection molding process, detect the pressure and slight deviation changes of the moving template 2 in real time, adaptively and dynamically adjust the distribution viscosity of the magnetorheological fluid 11, maintain the semi-solidified state, quickly change the local pressure bearing capacity, compensate for the slight deformation caused by the injection eccentric load on the local strain of the mold cavity, and reduce the clamping force fluctuation and error. The system maintains the clamping force by combining the clamping hydraulic cylinder 5 with the dynamic compensation of the magnetorheological fluid 11, quickly responds to problems such as pressure loss and clamping force fluctuation caused by local eccentric load, and uses closed-loop feedback to adjust the pulse current to reduce the comprehensive energy consumption of clamping. At the same time, it reduces the complex structure setting and maintenance requirements of mechanical precision electric control valves and mechanical devices required for high-precision pressure maintenance.

[0030] The above are all preferred embodiments of the present invention, and are not intended to limit the protection scope of the present invention. Therefore, any equivalent changes made based on the structure, shape, and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. An intelligent hydraulic clamping mechanism based on magnetorheological effect, comprising a fixed mold plate (1), a movable mold plate (2), a tail mold plate (3) and a guide thread tie rod (4), wherein the fixed mold plate (1), the movable mold plate (2) and the tail mold plate (3) are all mounted on the guide thread tie rod (4), and a clamping hydraulic cylinder (5) is fixed on the tail mold plate (3), characterized in that: A magnetorheological fluid bearing flange is installed between the clamping hydraulic cylinder (5) and the movable platen (2); The magnetorheological fluid bearing flange comprises a flange connection convex plate (6) and a flange connection concave plate (7). The flange connection convex plate (6) is connected to a push rod of a clamping hydraulic cylinder (5). A connection pad (12) is arranged between the flange connection concave plate (7) and a movable plate (2). Four pressure sensors (13) are arranged between the connection pad (12) and the movable plate (2). The four pressure sensors (13) are respectively mounted on four corners of the connection pad (12). The flange connection convex plate (6) and the flange connection concave plate (7) are buckled and fixed. The cavity between the flange connection convex plate (6) and the flange connection concave plate (7) is a closed cavity. A sealing ring (8) is arranged on the flange connection concave plate (7) for sealing the closed cavity. A permanent magnet (9) is embedded in the flange connection convex plate (6). An electromagnetic coil winding (10) as an excitation magnet is embedded in the flange connection concave plate (7). The closed cavity is filled with magnetorheological fluid (11).

2. The intelligent hydraulic clamping mechanism based on magnetorheological effect according to claim 1 is characterized in that: The magnetorheological fluid (11) is a silicone oil-based magnetorheological fluid containing ferrosoferric oxide nanoparticles.

3. According to claim 1, it is characterized in that: Sixteen permanent magnets (9) are provided, and the sixteen permanent magnets (9) are divided into two inner and outer circles and are evenly arranged along the circumferential direction of the flange connection convex plate (6). Sixteen electromagnetic coil windings (10) are also provided, and the sixteen electromagnetic coil windings (10) are divided into two inner and outer circles and are evenly arranged along the circumferential direction of the flange connection concave plate (7). The permanent magnets (9) correspond to the electromagnetic coil windings (10) one by one.

4. A clamping compensation method using the intelligent hydraulic clamping mechanism based on magnetorheological effect as claimed in claim 1: characterized in that, The steps include: S1, the clamping hydraulic cylinder (5) pushes the moving platen (2) to complete the mold closing and close the driving hydraulic pump, and the closed-loop feedback control system starts; S2, the pressure sensors (13) at the four corners of the connecting pad (12) detect the pressure setting value and distribution deviation of the connecting pad (12), the electromagnetic coil winding (10) is connected to the pulse current to generate a variable magnetic field, which is superimposed with the basic magnetic field provided by the permanent magnet (9) and acts on the magnetorheological fluid (11), so that the magnetorheological fluid (11) maintains a set semi-solidified state; S3, when the pressure loss or deviation fed back by the pressure sensor (13) exceeds a set threshold, the PID controller calculates the current adjustment amount and outputs a control signal to the current controller to perform current change adjustment of the electromagnetic coil winding (10); S4, the combined magnetic field changes the viscosity of the local magnetorheological fluid (11) at the corresponding position, and the pressure sensor (13) detects and updates the feedback pressure and deviation threshold changes in real time. When the design requirements are met, the coil current stops adjusting.

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