Servo valve control mechanism for injection molding machine and system thereof

Abstract

This invention discloses a servo valve control mechanism and system for an injection molding machine. The injection molding machine includes a screw, a motor for driving the rotational movement of the screw, and a hydraulic cylinder for driving the axial movement of the screw. The servo valve control mechanism controls the operating speed of the hydraulic cylinder and includes a proportional valve connected to the hydraulic cylinder for adjusting its operating speed, and a host computer connected to the proportional valve for adjusting its valve opening size. This invention eliminates the need for a controller; the position of the hydraulic cylinder is directly fed back to the host computer, which then performs the analysis and calculations directly, resulting in faster and more accurate calculations. Furthermore, it reduces wiring connections, simplifies the overall wiring layout, reduces the possibility of circuit interference, and significantly reduces machine and after-sales costs.

Description

Technical Field

[0001] This invention relates to the technical field of injection molding machines, and more particularly to a servo valve control mechanism and system for injection molding machines. Background Technology

[0002] The injection unit of an injection molding machine is the core injection unit of the entire machine, and the screw is a key component of the injection unit. The injection molding machine uses the screw to transport and melt the raw material, and finally inject it into the mold to form the shape. Therefore, the injection screw needs to move axially and rotate during the injection process.

[0003] Currently, injection molding machines primarily rely on hydraulic transmission for power, so the axial movement of the screw requires the drive of a hydraulic cylinder. Therefore, to ensure successful injection, precise control of the hydraulic cylinder's operating speed is necessary. In existing products, a host computer sends three signals—pressure, flow rate, and position—to the controller. The controller performs internal calculations and then sends instructions to the valve. The valve then outputs its valve core according to the controller's instructions. Throughout the control process, the cylinder's position or pressure value is fed back to the controller. The controller compares the host computer's instructions with the cylinder's feedback instructions and performs calculations and calibrations until the host computer's instruction value and the cylinder's feedback value are consistent. Summary of the Invention

[0004] (a) Technical problems to be solved

[0005] The technical problem to be solved by the present invention is to provide a servo valve control mechanism and system for an injection molding machine. The controller is eliminated, the position of the oil cylinder is directly fed back to the host computer, and the host computer directly analyzes and calculates the data, which is faster and more accurate. In addition, the number of wiring connections is reduced, the overall wiring layout is simpler, the possibility of circuit interference is reduced, and the machine cost and after-sales cost are greatly reduced.

[0006] (II) Technical Solution

[0007] The solution adopted by the present invention to solve the above-mentioned technical problem is a servo valve control mechanism for an injection molding machine. The injection molding machine includes a screw, a motor for driving the rotational movement of the screw, and a hydraulic cylinder for driving the axial movement of the screw. The servo valve control mechanism is used to control the operating speed of the hydraulic cylinder, including a proportional valve connected to the hydraulic cylinder for adjusting the operating speed of the hydraulic cylinder, and a host computer connected to the proportional valve for adjusting the valve opening size of the proportional valve.

[0008] Furthermore, the servo valve control mechanism also includes a resistance ruler for detecting the position of the hydraulic cylinder, and the resistance ruler is electrically connected to the host computer; the host computer includes a control module for analyzing and calculating the feedback from the resistance ruler.

[0009] Furthermore, the control module includes a PID control system.

[0010] By adopting the above solution, the controller is eliminated, the number of wiring connections is reduced, the overall wiring layout is simpler, the possibility of circuit interference is reduced, and the machine cost and after-sales cost are greatly reduced.

[0011] The solution adopted by the present invention to solve the above-mentioned technical problems is a servo valve control system for an injection molding machine, the servo valve control system comprising:

[0012] The hydraulic cylinder drive module is used to drive the axial movement of the screw.

[0013] A proportional valve control module is connected to the hydraulic cylinder drive module and is used to control the speed of the axial movement of the hydraulic cylinder drive module.

[0014] The host computer control module is connected to the proportional valve control module and the hydraulic cylinder drive module respectively, and is used to analyze and calculate based on the position value of the hydraulic cylinder drive module and send the signal to the proportional valve control module.

[0015] Furthermore, it also includes a position detection module, which is connected to the hydraulic cylinder drive module and the host computer control module respectively, for detecting the position of the hydraulic cylinder drive module and sending a signal to the host computer control module.

[0016] Preferably, the position detection module includes a resistance ruler.

[0017] Furthermore, the host computer control module includes a preset module and a PID control module connected to the preset module. The preset module includes a preset speed value. The PID control module is connected to the cylinder drive module and the proportional valve control module respectively. It is used to analyze and calculate the position of the cylinder drive module to obtain the actual speed value and compare it with the preset speed value. If the actual speed value is less than the preset speed value, the valve port of the proportional valve control module is opened wider. If the actual speed value is greater than the preset speed value, the valve port of the proportional valve control module is closed narrower.

[0018] Furthermore, the PID control module includes a PID calculation unit that uses differential calculation to calculate the position of the cylinder drive module, and a speed PID control unit for comparing the actual speed value with the preset speed value.

[0019] Furthermore, the preset module also includes a preset position value. The PID control module is used to analyze and calculate the preset position value to obtain a speed value, and compare it with the preset speed value. If the speed value is less than the preset speed value, the valve port of the proportional valve control module is controlled to open; if the speed value is greater than the preset speed value, the valve port of the proportional valve control module is controlled to close.

[0020] Furthermore, the PID control module includes a PID calculation unit that uses integral calculation to analyze and calculate the preset position value, and a speed PID control unit for comparing the speed value with the preset speed value.

[0021] Specifically, when the injection molding machine performs various actions, the host computer sends signals such as pressure and flow rate to the proportional valve. After receiving the instruction, the proportional valve starts working and simultaneously feeds back its current working status to the host computer. The host computer compares the values ​​fed back by the proportional valve with the target values ​​and optimizes them to form a closed-loop control of force and flow rate.

[0022] Furthermore, it also includes a motor drive module for driving the rotational movement of the screw.

[0023] Specifically, after the operator sets the preset speed value and preset position value, the PID calculation unit of the host computer will calculate a speed value by integration based on the preset position value and send this speed value to the speed PID control unit. The speed PID control unit of the host computer will compare the preset speed value with this speed value and then control the opening and closing of the proportional valve to control the movement of the hydraulic cylinder.

[0024] Once the hydraulic cylinder starts moving, its position is fed back to the host computer via a resistance gauge. The host computer's PID calculation unit performs differential calculations based on the resistance gauge feedback to obtain the current actual speed value. It then compares this actual speed value with the preset speed value. If the actual speed value is slower, it controls the proportional valve to open the valve port wider, thereby ensuring that the hydraulic cylinder speed matches the preset speed value.

[0025] (III) Beneficial Effects

[0026] Compared with the prior art, the present invention designs a servo valve control mechanism and system for an injection molding machine, which eliminates the controller. The position of the oil cylinder is directly fed back to the host computer, which also directly analyzes and calculates the data, making the calculation faster and more accurate. In addition, it reduces the number of wiring connections, making the entire wiring layout simpler, reducing the possibility of circuit interference, and greatly reducing the machine cost and after-sales cost. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of a servo valve control mechanism for an injection molding machine according to this embodiment;

[0028] Figure 2 This is a schematic diagram of a servo valve control system for an injection molding machine according to this embodiment;

[0029] Figure 3 This is a schematic diagram of the structure of a servo valve control system for an injection molding machine according to this embodiment.

[0030] Explanation of reference numerals in the attached diagram: 1. Screw; 2. Motor; 3. Hydraulic cylinder; 4. Proportional valve; 5. Host computer; 101. Hydraulic cylinder drive module; 102. Proportional valve control module; 103. Host computer control module; 1031. Preset module; 1031a. Preset speed value; 1031b. Preset position value; 1032. PID control module; 1032a. PID calculation unit; 1032b. Speed ​​PID control unit; 104. Position detection module. Detailed Implementation

[0031] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and should not be construed as limiting the scope of the invention.

[0032] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0033] This embodiment:

[0034] like Figure 1 As shown in this embodiment, a servo valve control mechanism for an injection molding machine includes a screw 1, a motor 2 for driving the rotation of the screw 1, and a hydraulic cylinder 3 for driving the axial movement of the screw 1. The servo valve control mechanism controls the operating speed of the hydraulic cylinder 3 and includes a proportional valve 4 connected to the hydraulic cylinder 3 for adjusting the operating speed of the hydraulic cylinder 3, and a host computer 5 connected to the proportional valve 4 for adjusting the valve opening size of the proportional valve 4. Further, the servo valve control mechanism also includes a resistance ruler for detecting the position of the hydraulic cylinder 3, and the resistance ruler is electrically connected to the host computer 5. The host computer 5 includes a control module for analyzing and calculating the feedback from the resistance ruler. In this embodiment, the control module is a PID control system. By adopting the above scheme, the controller is eliminated, the number of wiring connections is reduced, the overall wiring layout is simpler, the possibility of circuit interference is reduced, and the machine cost and after-sales cost are significantly reduced.

[0035] like Figures 1-3 As shown in this embodiment, a servo valve control system for an injection molding machine includes a cylinder drive module 101 for driving the axial movement of a screw 1; a proportional valve control module 102 connected to the cylinder drive module 101 and used to control the speed of the axial movement of the cylinder drive module 101; and a host computer control module 103 connected to both the proportional valve control module 102 and the cylinder drive module 101, used to analyze and calculate based on the position value of the cylinder drive module 101 and send a signal to the proportional valve control module 102. Further, a position detection module 104 is also included, connected to both the cylinder drive module 101 and the host computer control module 103, used to detect the position of the cylinder drive module 101 and send a signal to the host computer control module 103. Preferably, the position detection module 104 is a resistance ruler. Further, a motor drive module is also included for driving the rotational movement of the screw 1.

[0036] Furthermore, the host computer control module 103 includes a preset module 1031 and a PID control module 1032 connected to the preset module 1031. The preset module 1031 includes a preset speed value 1031a. The PID control module 1032 is connected to the cylinder drive module 101 and the proportional valve control module 102, respectively. It is used to analyze and calculate the position of the cylinder drive module 101 to obtain the actual speed value, and compare it with the preset speed value 1031a. If the actual speed value is less than the preset speed value 1031a, the valve of the proportional valve control module 102 is opened wider; if the actual speed value is greater than the preset speed value 1031a, the valve of the proportional valve control module 102 is closed narrower. Furthermore, the PID control module 1032 includes a PID calculation unit 1032a, which uses differential calculation to calculate the position of the cylinder drive module 101, and a speed PID control unit 1032b, which is used to compare the actual speed value and the preset speed value 1031a. Furthermore, the preset module 1031 also includes a preset position value 1031b. The PID control module 1032 is used to analyze and calculate the preset position value 1031b to obtain a speed value, and compare it with the preset speed value 1031a. If the speed value is less than the preset speed value 1031a, the valve port of the proportional valve control module 102 is opened; if the speed value is greater than the preset speed value 1031a, the valve port of the proportional valve control module 102 is closed. Furthermore, the PID control module 1032 includes a PID calculation unit 1032a, which uses integral calculation to analyze and calculate the preset position value 1031b, and a speed PID control unit 1032b, used to compare the speed value with the preset speed value 1031a. Specifically, when the injection molding machine performs various actions, the host computer 5 sends pressure, flow and other signals to the proportional valve 4. After receiving the instruction, the proportional valve 4 starts to work. At the same time, the proportional valve 4 feeds back the current working status to the host computer 5 in real time. The host computer 5 compares the values ​​fed back by the proportional valve 4 with the target values ​​and optimizes them to form a closed-loop control of force and flow.

[0037] In use, after the operator sets the preset speed value 1031a and the preset position value 1031b, the PID calculation unit 1032a of the host computer 5 will calculate a speed value by integration based on the preset position value 1031b, and send this speed value to the speed PID control unit 1032b. The speed PID control unit 1032b of the host computer 5 will compare the preset speed value 1031a with the speed value, and then control the opening and closing of the proportional valve 4 to control the action of the hydraulic cylinder 3.

[0038] When the hydraulic cylinder 3 starts to move, the position of the hydraulic cylinder 3 is fed back to the host computer 5 through the resistance ruler. The PID calculation unit 1032a of the host computer 5 performs differential calculation based on the feedback from the resistance ruler to obtain the current actual speed value. It then compares the actual speed value with the preset speed value 1031a. If the actual speed value is slower, it controls the proportional valve 4 to open the valve port wider, so as to make the speed of the hydraulic cylinder 3 consistent with the preset speed value 1031a.

[0039] The above are merely preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A servo valve control system for an injection molding machine applied to a servo valve control mechanism, the injection molding machine comprising a screw (1), a motor (2) for driving the rotational movement of the screw (1), and a hydraulic cylinder (3) for driving the axial movement of the screw (1); characterized in that: The servo valve control mechanism is used to control the running speed of the hydraulic cylinder (3), including a proportional valve (4) connected to the hydraulic cylinder (3) for adjusting the running speed of the hydraulic cylinder (3), and a host computer (5) connected to the proportional valve (4) for adjusting the valve port size of the proportional valve (4); the servo valve control mechanism also includes a resistance ruler for detecting the position of the hydraulic cylinder (3), and the resistance ruler is electrically connected to the host computer (5); the host computer (5) includes a control module for analyzing and calculating the feedback from the resistance ruler; the control module includes a PID control system; The servo valve control system includes The hydraulic cylinder drive module (101) is used to drive the axial movement of the screw (1); A proportional valve control module (102) is connected to the cylinder drive module (101) and is used to control the speed of the axial movement of the cylinder drive module (101); The host computer control module (103) is connected to the proportional valve control module (102) and the cylinder drive module (101) respectively, and is used to analyze and calculate the position value of the cylinder drive module (101) and send the signal to the proportional valve control module (102). It also includes a position detection module (104), which is connected to the cylinder drive module (101) and the host computer control module (103) respectively, for detecting the position of the cylinder drive module (101) and sending a signal to the host computer control module (103). The host computer control module (103) includes a preset module (1031) and a PID control module (1032) connected to the preset module (1031). The preset module (1031) includes a preset speed value (1031a). The PID control module (1032) is connected to the cylinder drive module (101) and the proportional valve control module (102) respectively. It is used to analyze and calculate the position of the cylinder drive module (101) to obtain the actual speed value, and compare it with the preset speed value (1031a). If the actual speed value is less than the preset speed value (1031a), the valve port of the proportional valve control module (102) is opened wider. If the actual speed value is greater than the preset speed value (1031a), the valve port of the proportional valve control module (102) is closed smaller. The PID control module (1032) includes a PID calculation unit (1032a) that uses differential calculation to calculate the position of the cylinder drive module (101) and a speed PID control unit (1032b) that compares the actual speed value with the preset speed value (1031a). The preset module (1031) further includes a preset position value (1031b). The PID control module (1032) is used to analyze and calculate the preset position value (1031b) to obtain a speed value, and compare it with the preset speed value (1031a). If the speed value is less than the preset speed value (1031a), the valve port of the proportional valve control module (102) is controlled to open; if the speed value is greater than the preset speed value (1031a), the valve port of the proportional valve control module (102) is controlled to close. The PID control module (1032) includes a PID calculation unit (1032a) that uses integral calculation to analyze and calculate the preset position value (1031b) and a speed PID control unit (1032b) for comparing the speed value with the preset speed value (1031a).

2. The servo valve control system for an injection molding machine applied to a servo valve control mechanism according to claim 1, characterized in that: It also includes a motor drive module for driving the rotation of the screw (1).

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