Quick-response injection molding machine green column high-precision position control system

Abstract

The invention relates to the technical field of injection molding machines, in particular to a quick-response injection molding machine green column high-precision position control system which comprises an electromagnetic valve which is a two-position four-way electromagnetic valve and used for controlling on-off and switching of an oil way. The sequence valve has a one-way conduction characteristic and is used for limiting the locking pressure and protecting a structural part driven by the execution element; the pressure oil cylinder is used as an execution element for driving the green column; when the electromagnetic valve is powered off, the sequence valve rear oil way is communicated with a rodless cavity oil way in the pressure oil cylinder so as to control stretching and retracting of the Green column. When the electromagnetic valve is powered on, the sequence valve rear oil way is disconnected with the rodless cavity oil way in the pressure oil cylinder so as to lock the position of the Green column. The number of control elements in the control system of the green column is simplified from five to two, the control system of the green column is greatly simplified, the size of the control system is reduced accordingly, and the overall manufacturing cost is reduced by two thirds.

Description

Technical Field

[0001] The present invention relates to the technical field of injection molding machines, and in particular to a fast-response Green column high-precision position control system for an injection molding machine. Background Art

[0002] An injection molding machine, also known as an injection molding machine or injection molding machine, is the primary molding equipment used to create various shapes of plastic products from thermoplastics or thermosetting plastics using plastic molding molds. The Green rod (also known as a tie rod or guide rod) is a key component of the injection molding machine's mold clamping system, used to support and position the mold.

[0003] Currently, the position control of the Green column (such as Figure 2 As shown, the existing technology primarily controls the output oil from the rod chamber, employing a system consisting of a pressure cylinder, a first valve block 10, a cartridge valve 11, a second valve block 12, a pilot valve 13, a shuttle valve 15, a safety valve 14, and a throttle plug. When pilot valve 13 is not operating normally, cartridge valve 11 is in an open state, allowing the extension and retraction of the Green column to be controlled according to the system's main valve. When pilot valve 13 is operating, cartridge valve 11 is locked, locking the Green column position. Shuttle valve 15 provides a control oil source for pilot valve 13. Safety valve 14 limits system pressure to no more than 25 bar, protecting the structural components driven by the actuator from exceeding their stress range and ensuring safe and stable operation of the machine.

[0004] However, the current control system structure of the Green column is complex, the system requires a large number of hydraulic components, and the control logic is complex. The pilot valve 13 is used to control the main valve, and the shuttle valve 15 is also required to determine the pressure before and after the valve, and then provide pressure output to the pilot valve 13, resulting in a control delay of 20 to 50ms and poor accuracy. Therefore, we proposed a fast-response Green column high-precision position control system for injection molding machines to solve the above problems. Summary of the Invention

[0005] The present invention aims to solve the defects of Green column control systems in the prior art, such as complex structure and relatively poor precision, and provides a fast-response Green column high-precision position control system for an injection molding machine.

[0006] The present invention is achieved through the following technical solutions:

[0007] A fast-response, high-precision Green Column position control system for injection molding machines, comprising:

[0008] Solenoid valve, a 2-position 4-way solenoid valve, is used to control the on / off and switching of the oil circuit. When a large flow rate is required, the internal oil passages of the valve and the oil passages of the valve block are used to double the flow capacity, and the flow capacity can replace the traditional pilot cartridge valve.

[0009] Sequence valve, which has a one-way conduction characteristic and is used to limit the locking pressure and protect the structural parts driven by the actuator;

[0010] The pressure cylinder is used as an actuator to drive the Green column;

[0011] Wherein, when the solenoid valve is powered off, the oil circuit after the sequence valve is connected to the rodless chamber oil circuit of the pressure oil cylinder to control the extension and retraction of the Green column;

[0012] Secondly, when the solenoid valve is energized, the oil circuit after the sequence valve is disconnected from the oil circuit of the rodless chamber to lock the position of the Green column.

[0013] In a preferred embodiment of the present invention, the solenoid valve is provided with a P port, a T port, an A port and a B port. When no power is supplied, the right position is the working position, at which time the P port is connected to the A port and the T port is connected to the B port; when power is supplied, the left position is the working position, at which time the P port is connected to the B port and the T port is connected to the A port.

[0014] In a preferred embodiment of the present invention, the P port on the solenoid valve is connected to the oil inlet of the sequence valve, the T port is connected to the external oil tank, and the A port and the B port switch the connection object according to the working state of the solenoid valve.

[0015] In a preferred embodiment of the present invention, the oil inlet of the sequence valve is connected to the rodless chamber oil circuit in the pressure cylinder, and the oil outlet of the sequence valve is connected to the solenoid valve B port or the external oil tank according to the state of the solenoid valve.

[0016] In a preferred embodiment of the present invention, the pressure oil cylinder is connected to the oil inlet of the sequence valve, or is connected to port B when the solenoid valve is energized.

[0017] In a preferred embodiment of the present invention, a pressure measuring joint is further included, and the pressure measuring joint is used to connect to a pressure measuring device to measure the pressure of the rodless chamber of the pressure oil cylinder.

[0018] In a preferred embodiment of the present invention, the solenoid valve, sequence valve and pressure measuring joint are all integrated and installed through the valve block and accessories. At the same time, compared with the current Green Column control system, the solution in this application reduces the control elements, so that the volume of the valve block is smaller than that of the traditional system, and the overall manufacturing cost is reduced by two-thirds.

[0019] In a preferred embodiment of the present invention, the set pressure of the sequence valve is not higher than the set value. When the pressure in the rodless chamber of the pressure cylinder exceeds the preset value, the sequence valve opens and connects the oil circuit to limit the locking pressure and prevent malfunction caused by pressure interference during locking.

[0020] In a preferred embodiment of the present invention, the one-way conduction direction of the sequence valve is from the rodless chamber oil circuit in the pressure oil cylinder to the rear oil circuit of the sequence valve, and is blocked in the reverse direction.

[0021] In a preferred embodiment of the present invention, a sensor and a controller are further included. The sensor is used to detect the position of the Green column and feed back the detection signal to the controller. The controller controls the on and off of the solenoid valve according to the feedback signal. The controller adopts a PID control algorithm or an adaptive control algorithm to output a 24V signal to directly drive the on and off control of the solenoid valve.

[0022] In a preferred embodiment of the present invention, the sensor is a position sensor or a grating ruler.

[0023] In a preferred embodiment of the present invention, the controller is a motion controller or a PLC controller.

[0024] The beneficial effects of the present invention are:

[0025] 1. This application adopts a 2-position 4-way solenoid valve, which uses the internal oil passages of the valve and the oil passages of the valve block to increase the flow capacity by 1 times. The flow capacity replaces the traditional pilot cartridge valve, and when the solenoid valve is energized, the rodless chamber in the pressure cylinder must be connected to the external oil source through the sequence valve, and the sequence valve is unidirectionally guided and reversely locked to maintain the pressure of the rodless chamber to lock the Green column position, thereby achieving Green column locking. The control components are simplified from 5 to 2, which greatly simplifies the control system of the Green column, reduces its volume, and reduces the overall manufacturing cost by two-thirds.

[0026] 2. The traditional Green Column control method uses a pilot valve to control the main valve, and a shuttle valve is required to determine the pressure before and after the valve, and then provide pressure output to the pilot valve, resulting in a control delay of 20 to 50 ms and a total control response time of about 100 ms. The 2-position 4-way solenoid valve used in the present invention has a total control response time of about 50 ms, which greatly shortens the response time and thus improves the position control accuracy and repeatability.

[0027] 3. This system lacks pilot-stage control and adopts 24V voltage or 0-25ma current signal direct drive control, eliminating excessive pilot oil circuits and throttle plugs, thereby reducing the risk of oil circuits being blocked by impurities and lowering the overall failure rate; while eliminating the pilot-stage control, it fully utilizes the oil channel of the 2-position 4-way solenoid valve, and through the innovative right-path arrangement, it realizes simultaneous and unidirectional oil flow in the two oil channels, and the flow capacity is equivalent to the flow capacity of the pilot-stage control. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a block diagram of a fast-response Green column high-precision position control system for an injection molding machine according to the present invention;

[0029] Figure 2 It is a block diagram of Green column control system in the prior art;

[0030] Figure 3This is a component connection diagram of a fast-response Green column high-precision position control system for an injection molding machine according to the present invention.

[0031] In the figure: 1. Sequence valve; 2. Solenoid valve; 3. Pressure measuring joint; 4. Valve block and accessories; 5. Pressure cylinder; 10. First valve block; 11. Cartridge valve; 12. Second valve block; 13. Pilot valve; 14. Safety valve; 15. Shuttle valve. DETAILED DESCRIPTION

[0032] The following detailed description of preferred embodiments of the present invention is provided in conjunction with the accompanying drawings to facilitate understanding of the advantages and features of the present invention by those skilled in the art, thereby providing a clearer and more precise definition of the scope of protection of the present invention. Directional terms used in the present invention, such as "up," "down," "front," "back," "left," "right," "top," and "bottom," are intended solely to refer to the directions of the accompanying drawings. Therefore, the directional terms used are intended to illustrate and facilitate understanding of the present invention and are not intended to limit the present invention.

[0033] like Figure 1-3 The fast-response Green Column high-precision position control system for an injection molding machine shown in the figure includes a solenoid valve 2, a sequence valve 1, a pressure measuring joint 3, and a pressure cylinder 5. The solenoid valve 2 is a 2-position 4-way solenoid valve. The solenoid valve 2 is provided with a P port, a T port, an A port, and a B port. When the power is off, the right position is the working position, at which point the P port is connected to the A port and the T port is connected to the B port. When the power is on, the left position is the working position, at which point the P port is connected to the B port and the T port is connected to the A port.

[0034] The solenoid valve 2 is controlled on and off by the controller outputting a 24V electrical signal. The P port on the solenoid valve 2 is connected to the oil inlet of the sequence valve 1, and the T port is connected to the external oil tank. The A port and the B port switch the connection object according to the working state of the solenoid valve 2 to control the on and off and switching of the oil circuit. When a large flow is required, the internal oil channel of the valve and the oil channel of the valve block are used to increase the flow capacity by 1 times. In terms of flow capacity, it can replace the traditional pilot cartridge valve;

[0035] The sequence valve 1 has a one-way conduction characteristic. The one-way conduction direction of the sequence valve 1 is from the rodless chamber oil circuit in the pressure oil cylinder 5 to the rear oil circuit of the sequence valve 1, and is cut off in the reverse direction.

[0036] The oil inlet of sequence valve 1 is connected to the oil circuit of the rodless chamber in pressure oil cylinder 5. The oil outlet of sequence valve 1 is connected to port B of solenoid valve 2 or an external oil tank according to the state of solenoid valve 2. The set pressure of sequence valve 1 is not higher than the set value. According to experience, the set value is 50 bar. When the pressure in the rodless chamber of pressure oil cylinder 5 exceeds the preset value, sequence valve 1 opens and connects the oil circuit to limit the locking pressure and prevent malfunction caused by pressure interference during locking, and protect the structural parts driven by the actuator;

[0037] The rodless chamber in the pressure oil cylinder 5 is connected to the oil inlet of the sequence valve 1, or is connected to the B port when the solenoid valve 2 is energized. The rod chamber is connected to the system main valve, which controls the oil in and out to drive the Green column to extend and retract. It is used as an actuator to drive the Green column.

[0038] The pressure measuring joint 3 is connected to a pressure gauge to monitor in real time whether the pressure in the rodless chamber exceeds 50 bar, and to judge the working state of the sequence valve 1 (it opens when the internal pressure exceeds the preset 50 bar);

[0039] When the solenoid valve 2 is energized, the P port is connected to the B port, and the T port is connected to the A port. At this time, the rodless chamber in the pressure oil cylinder 5 must be connected to the external oil source through the sequence valve 1. At this time, the sequence valve 1 is unidirectional and reversely locked, maintaining the pressure of the rodless chamber to lock the Green column position;

[0040] When the solenoid valve 2 loses power, the P port is connected to the A port, and the T port is connected to the B port. At this time, the rodless cavity in the pressure cylinder 5 is directly connected to the external oil source through the solenoid valve 2, skipping the sequence valve 1. The system main valve controls the oil flow to realize the extension and retraction of the Green column.

[0041] Specifically, the solenoid valve 2, the sequence valve 1 and the pressure measuring joint 3 are all integrated and installed through the valve block and the accessories 4. At the same time, compared with the current Green Column control system, the solution in this application reduces the control elements, so that the volume of the valve block is smaller than that of the traditional system, and the overall manufacturing cost is reduced by two-thirds.

[0042] Furthermore, it also includes a sensor and a controller. The sensor can be a position sensor or a grating ruler, installed on the motion path of the Green column. The controller can be a motion controller or a PLC controller. The sensor is used to detect the position of the Green column and feed back the detection signal to the controller. The controller controls the on and off of the solenoid valve 2 according to the feedback signal. The controller adopts a PID control algorithm or an adaptive control algorithm to output a 24V signal to directly drive the control of the on and off of the solenoid valve 2.

[0043] The control process is as follows: the sensor detects the position of the Green bar → feeds back to the controller → the controller calculates the control signal based on the deviation → outputs a 24V signal to the solenoid valve 2 → adjusts the oil circuit → corrects the Green bar position.

[0044] In this embodiment, when the solenoid valve 2 is energized, the P port is connected to the B port, and the T port is connected to the A port. At this time, the rodless chamber in the pressure oil cylinder 5 must be connected to the external oil source through the sequence valve 1. At this time, the sequence valve 1 is unidirectional and reversely locked, maintaining the pressure of the rodless chamber to lock the Green column position;

[0045] When the solenoid valve 2 loses power, the P port is connected to the A port, and the T port is connected to the B port. At this time, the rodless cavity in the pressure cylinder 5 is directly connected to the external oil source through the solenoid valve 2, skipping the sequence valve 1. The system main valve controls the oil flow to realize the extension and retraction of the Green column.

[0046] The system's hydraulic control components are reduced from 5 to 2 (solenoid valve 2 and sequence valve 1), eliminating traditional components such as cartridge valve 11, pilot valve 13, shuttle valve 15, safety valve 14 and throttle plug. The connection path is simplified by more than 50%, and the risk of oil circuit blockage by impurities is reduced by 80%. The system control response time is ≤50ms, which is more than 50% shorter than the traditional system (response time >100ms), and the position repeatability accuracy reaches ±0.05mm.

[0047] It should be noted that the parts not covered by the present invention are the same as the existing technology or can be implemented by using the existing technology; the various drives in the present invention can be implemented by using corresponding power structures such as cylinders, oil cylinders, electric cylinders, motors, etc. in combination with connecting rods, guide rods, etc., and are not limited to the description in the specification and the structure in the drawings.

[0048] In the description of the embodiments of the present invention, unless otherwise expressly specified or limited, the terms "installed," "connected," "connected," "disposed," and "provided with" should be understood in a broad sense. For example, they may refer to fixed, detachable, or integral connections; mechanical or electrical connections; direct or indirect connections through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention in specific contexts.

[0049] The above-described embodiments merely illustrate several implementations of the present invention. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, and all such variations and improvements fall within the scope of protection of the present invention.

Claims

1. A fast-response Green column high-precision position control system for injection molding machines, characterized in that: include: Solenoid valve (2), the solenoid valve (2) is a 2-position 4-way solenoid valve, used to control the on / off and switching of the oil circuit; A sequence valve (1) having a one-way conduction characteristic, used for limiting a locking pressure and protecting a structural component driven by an actuator; A pressure oil cylinder (5) is used as an actuator to drive the Green column; When the solenoid valve (2) is powered off, the rear oil circuit of the sequence valve (1) is connected to the rodless chamber oil circuit in the pressure oil cylinder (5) to control the extension and contraction of the Green column; Secondly, when the electromagnetic valve (2) is energized, the rear oil circuit of the sequence valve (1) is disconnected from the rodless chamber oil circuit in the pressure oil cylinder (5) to lock the position of the Green column.

2. The fast-response Green column high-precision position control system for an injection molding machine according to claim 1, characterized in that: The solenoid valve (2) is provided with a P port, a T port, an A port and a B port. When the power is off, the right position is the working position, at which time the P port is connected to the A port and the T port is connected to the B port; when the power is on, the left position is the working position, at which time the P port is connected to the B port and the T port is connected to the A port.

3. The fast-response Green column high-precision position control system for an injection molding machine according to claim 2, characterized in that: The P port on the solenoid valve (2) is connected to the oil inlet of the sequence valve (1), the T port is connected to the external oil tank, and the A port and the B port switch the connection object according to the working state of the solenoid valve (2).

4. The fast-response Green column high-precision position control system for an injection molding machine according to claim 3, characterized in that: The oil inlet of the sequence valve (1) is connected to the rodless chamber oil circuit in the pressure oil cylinder (5), and the oil outlet of the sequence valve (1) is connected to the B port of the solenoid valve (2) or an external oil tank according to the state of the solenoid valve (2).

5. The fast-response Green column high-precision position control system for an injection molding machine according to claim 4, characterized in that: The pressure oil cylinder (5) is connected to the oil inlet of the sequence valve (1), or is connected to the B port when the electromagnetic valve (2) is energized.

6. The fast-response Green column high-precision position control system for an injection molding machine according to claim 1, characterized in that: It also includes a pressure measuring joint (3), which is used to connect a pressure measuring device to measure the pressure of the rodless chamber of the pressure oil cylinder (5).

7. The fast-response Green column high-precision position control system for an injection molding machine according to claim 6, characterized in that: The solenoid valve (2), sequence valve (1) and pressure measuring joint (3) are all integrated and installed via a valve block and auxiliary components (4).

8. The fast-response Green column high-precision position control system for an injection molding machine according to claim 1, characterized in that: The set pressure of the sequence valve (1) is not higher than a set value, and the sequence valve (1) opens when the pressure of the rodless chamber in the pressure oil cylinder (5) exceeds the preset value.

9. The fast-response Green column high-precision position control system for an injection molding machine according to claim 1, characterized in that: The one-way conducting direction of the sequence valve (1) is from the rodless chamber oil circuit in the pressure oil cylinder (5) to the rear oil circuit of the sequence valve (1).

10. The fast-response Green column high-precision position control system for an injection molding machine according to claim 1, characterized in that: It also includes a sensor and a controller, wherein the sensor is used to detect the position of the Green column and feed back the detection signal to the controller, and the controller controls the on and off of the solenoid valve (2) according to the feedback signal.

11. The fast-response Green column high-precision position control system for an injection molding machine according to claim 10, characterized in that: The sensor is a position sensor or a grating ruler.

12. The fast-response Green column high-precision position control system for an injection molding machine according to claim 10, characterized in that: The controller is a motion controller or a PLC controller.

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