A driving mechanism for injection molding machine injection stage

Abstract

This utility model relates to the field of injection molding machine control system technology, and discloses an injection stage drive mechanism for an injection molding machine. A hydraulic cylinder is provided between the front end of the injection stage body and the fixed platen for driving the injection stage body to engage with the gate in a first state and for driving the injection stage body away from the fixed platen in a second state. A hydraulic system for controlling the extension and retraction of the hydraulic cylinder is connected to the cylinder, and a pressure detection unit is provided on the cylinder or hydraulic system. When the injection stage body is in the first state, the pressure detection unit can detect the hydraulic pressure inside the cylinder or hydraulic system to determine the contact force between the injection stage body and the gate. With this injection stage drive mechanism, after the injection stage engages with the fixed platen, the pressure detection unit detects the hydraulic pressure value inside the cylinder or hydraulic system to obtain the cylinder's thrust pressure, thereby determining the contact force between the injection stage nozzle and the gate of the fixed platen, thus reducing the risk of over-engagement and injection leakage.

Description

Technical Field

[0001] This utility model relates to the field of injection molding machine control system technology, and in particular to an injection molding machine stage drive mechanism. Background Technology

[0002] The injection molding machine's injection unit is one of the core components of the injection molding machine, primarily responsible for melting, plasticizing, and injection molding of plastic. Its functions include feeding, melting, and injection: the screw rotates to shear and melt plastic granules (melting process), and then injects the molten plastic into the mold under high pressure (injection process). A similar injection molding machine injection unit is disclosed in Chinese invention patent publication number CN109955436A.

[0003] The injection molding machine's injection station needs to move forward and backward during injection, cleaning, and maintenance. Before actually producing a product, the injection station needs to move forward and connect with the mold gate to form a certain contact force to prevent material leakage.

[0004] Traditional injection molding machine injection units are typically driven by a motor and lead screw or a motor and pulley, with position switches determining whether the injection unit has moved into position. However, when the position switch detects that the injection unit is aligned with the mold gate, it sends a signal to the controller, which then controls the injection mechanism to perform injection. During this process, due to the limitations of the position switch, it cannot determine the tightness of the connection between the injection nozzle and the mold gate (i.e., the contact force between them), thus posing a risk of over-alignment or injection leakage, and therefore requires improvement. Utility Model Content

[0005] This invention addresses the shortcomings of existing technologies by providing an injection molding machine stage drive mechanism that can both advance and retreat the injection stage and detect the contact force between the injection stage and the fixed template after they are aligned, thereby reducing the risk of over-alignment and injection leakage.

[0006] To solve the above-mentioned technical problems, the present invention provides a solution through the following technical method: An injection molding machine injection unit drive mechanism includes an injection unit body, a fixed platen, and a gate formed on the fixed platen. A hydraulic cylinder is provided between the front end of the injection unit body and the fixed platen for driving the injection unit body to engage with the gate in a first state and driving the injection unit body away from the fixed platen in a second state. A hydraulic system for controlling the extension and retraction of the hydraulic cylinder is connected to the hydraulic cylinder. A pressure detection unit is provided on the hydraulic cylinder or the hydraulic system. When the injection unit body is in the first state, the pressure detection unit can detect the hydraulic pressure inside the hydraulic cylinder or the hydraulic system to determine the contact force between the injection unit body and the gate.

[0007] By employing the above-mentioned solution, the movement of the injection unit body driven by a hydraulic cylinder can improve the smoothness of the injection unit's advance and retreat. Simultaneously, the hydraulic pressure within the hydraulic system provides a certain buffering force, making the contact between the injection unit and the gate on the fixed platen more gentle, thereby reducing the impact between them. After the injection unit and the fixed platen are connected, the hydraulic pressure value in the hydraulic cylinder or hydraulic system is detected by a pressure detection unit to obtain the cylinder's jacking pressure. This allows for the determination of the contact force between the injection nozzle and the gate on the fixed platen, thus reducing the risk of over-connection and injection leakage.

[0008] Preferably, the hydraulic system includes an oil tank, an oil pump, and a valve assembly connected in sequence via an oil circuit. The oil cylinder is connected to and controlled by the valve assembly. The oil pump is used to draw hydraulic oil from the oil tank into the oil circuit to drive the oil cylinder to run. The valve assembly is used to switch the direction of the oil circuit to change the extension and retraction direction of the oil cylinder.

[0009] Using the above scheme, the speed of the oil pump can control the forward and backward speed and the jacking pressure of the oil cylinder, and the valve assembly can change the extension and retraction direction of the oil cylinder, thereby achieving efficient control of the oil cylinder.

[0010] Preferably, the cylinder sidewall of the hydraulic cylinder has a detection hole, and the pressure detection unit is installed in the detection hole.

[0011] The above solution enables the pressure detection unit to accurately detect the hydraulic pressure inside the cylinder.

[0012] Preferably, an internal threaded bushing is provided on the outside of the detection hole for the pressure detection unit to be threaded into.

[0013] By adopting the above solution, the threaded fit between the pressure detection unit and the internal threaded bushing can not only improve the ease of disassembly and assembly of the pressure detection unit, but also ensure its stability after installation.

[0014] Preferably, the outer ring of the pressure detection unit is provided with a compression ring, and a sealing ring is provided between the compression ring and the internal thread bushing.

[0015] By adopting the above solution, the sealing ring can improve the sealing performance between the pressure detection unit and the internal threaded bushing, thereby preventing hydraulic oil leakage in the cylinder.

[0016] Preferably, a three-way connector is provided in the oil circuit, with the inlet of the three-way connector connected in series with one of its outlets in the oil circuit, and the pressure detection unit connected to the other outlet of the three-way connector.

[0017] The above solution ensures that the pressure detection unit can be stably installed on the oil circuit of the hydraulic system, and guarantees the stability of the installation.

[0018] Preferably, the pressure detection unit is sequentially coupled with a controller and a drive unit, and the valve assembly is coupled to and controlled by the controller. The hydraulic system also includes a power source for driving the oil pump and coupled to the drive unit. The controller has a preset pressure threshold. When the injection unit is in the first state, the pressure detection unit can detect the hydraulic pressure in the cylinder or hydraulic system. If the measured hydraulic pressure value is greater than the pressure threshold, the controller reduces the operating speed of the power source through the drive unit to lower the hydraulic pressure value to the pressure threshold and controls the valve assembly to lock the oil circuit, thereby achieving pressure holding. Conversely, if the measured hydraulic pressure value is less than the pressure threshold, the controller increases the operating speed of the power source through the drive unit to raise the hydraulic pressure value back to the pressure threshold and controls the valve assembly to lock the oil circuit, thereby achieving pressure holding.

[0019] Using the above scheme, the pressure detection unit, controller, drive unit and power source can form a feedback adjustment loop to dynamically adjust the jacking pressure of the oil cylinder according to the pressure threshold built into the controller, so that the jacking pressure is maintained at the pressure threshold, thereby ensuring the balance of contact force between the injection stage body and the fixed template gate.

[0020] Preferably, the drive unit is a frequency converter.

[0021] By adopting the above scheme, the frequency converter can achieve stepless speed regulation of the power source, making the forward and backward movement of the hydraulic cylinder and the injection platform more stable and smooth.

[0022] Preferably, the controller is also coupled to an input unit that responds to external triggers to adjust pressure threshold parameters.

[0023] By adopting the above solution, users can input the required pressure threshold to the controller according to the characteristics of different products, thereby improving the applicability of the injection molding machine.

[0024] Preferably, the push rod and cylinder of the hydraulic cylinder are fixed to the front side of the fixed template and the front side of the launching platform body respectively by hinges.

[0025] By adopting the above scheme, the hinge seat allows the hydraulic cylinder to form a certain amount of movement space between the launcher body and the fixed template. This ensures the stability and smoothness of the launcher body when moving forward and backward, and reduces the installation accuracy requirements of the hydraulic cylinder, thereby reducing the processing difficulty and saving costs.

[0026] This invention, by employing the above technical solutions, achieves significant technical advantages: The hydraulic cylinder drives the injection unit to move, improving the smoothness of the injection unit's advance and retreat. Simultaneously, the hydraulic pressure within the hydraulic system provides a buffering force, resulting in a gentler connection between the injection unit and the gate on the fixed mold plate, thus reducing impact. After the injection unit and fixed mold plate are connected, the hydraulic pressure value within the cylinder or hydraulic system is detected by the pressure detection unit. This allows for the determination of the cylinder's thrust pressure, thereby assessing the contact force between the injection nozzle and the gate on the fixed mold plate, further reducing the risk of over-connection and injection leakage. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the structure of this embodiment. Figure 1 ; Figure 2 This is a schematic diagram of the structure of this embodiment. Figure 2 ; Figure 3 This is a schematic diagram of the structure of this embodiment. Figure 3 ; Figure 4 This is a schematic diagram of the structure of this embodiment. Figure 4 ; Figure 5 This is a schematic diagram of the structure of this embodiment. Figure 5 ; Figure 6 This is a system architecture diagram for this embodiment; Figure 7 This is a schematic diagram of the structure of this embodiment. Figure 6 .

[0028] The parts referred to by the numbers in the above attached diagrams are as follows: 1. Injection unit body; 2. Fixed mold plate; 3. Gate; 4. Hydraulic cylinder; 5. Pressure detection unit; 6. Oil circuit; 7. Oil tank; 8. Oil pump; 9. Valve assembly; 10. Detection hole; 11. Internal threaded bushing; 12. Extrusion ring; 13. Sealing ring; 14. T-joint; 15. Inlet; 16. Controller; 17. Drive unit; 18. Power source; 19. Input unit; 20. Push rod; 21. Hinge seat; 22. Barrel; 23. Nozzle; 24. Cylinder; 25. Guide block; 26. Guide rail; 27. Injection molding machine; 28. Worktable; 29. ​​Position and speed sensor; 30. Outlet. Detailed Implementation

[0029] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments.

[0030] like Figures 1 to 6As shown, this embodiment discloses an injection molding machine injection unit drive mechanism, including an injection unit body 1, a fixed platen 2 located on the front side of the injection unit body 1, and a gate 3 opened on the side of the fixed platen 2 near the injection unit body 1. An injection barrel 22 is fixedly installed on the front side of the injection unit body 1, and a nozzle 23 for docking with the gate 3 is provided at the front end of the barrel 22. For ease of description, the state in which the injection unit body 1 docks with the gate 3 is the state in which the nozzle 23 docks with the gate 3, and the state in which the injection unit body 1 moves away from the gate 3 is the state in which the nozzle 23 is separated from the gate 3. In this embodiment, a hydraulic cylinder 4 is provided between the front end of the injection unit body 1 and the fixed platen 2 for driving the injection unit body 1 to dock with the gate 3 in a first state and driving the injection unit body 1 away from the fixed platen 2 in a second state. The push rod 20 and the cylinder barrel 24 of the hydraulic cylinder 4 are both fixed to the fixed platen 2 and the front side of the injection unit body 1 respectively by hinge seats 21. There are two hydraulic cylinders 4, which are respectively located on both sides of the barrel 22 to achieve the purpose of force balance.

[0031] To improve the stability and smoothness of the injection stage body 1 during movement, two guide blocks 25 are fixedly installed at the bottom of the injection stage body 1, and two guide rails 26 are installed below the injection stage body 1 for the two guide blocks 25 to slide and engage. The guide rails 26 are fixed above the worktable 28 of the injection molding machine 27.

[0032] To detect the extension and retraction of the hydraulic cylinder 4 and the contact force between the injection unit body 1 and the fixed mold plate 2, a hydraulic system for controlling the extension and retraction of the hydraulic cylinder 4 is connected to the hydraulic cylinder 4. This hydraulic system is a closed hydraulic system specifically used to drive the forward and backward movement of the injection unit and to establish pressure between the gate 3 and the mold. The injection, mold closing, material storage, and ejection actions of the electric injection molding machine 27 are controlled by a servo motor (not shown). The forward and backward movement of the injection unit and the establishment of pressure between the gate 3 and the mold are achieved using an independent hydraulic pump, which has the advantages of high efficiency, simple structure, and stable control. Compared with the traditional drive method using lead screws or pulleys, the structure is simpler, the stability is higher, and the risk of material leakage from the gate 3 and the nozzle is lower. A pressure detection unit 5 is provided on the hydraulic cylinder 4 or the hydraulic system, and the pressure detection unit 5 is preferably a hydraulic pressure sensor. In this embodiment, when the injection unit body 1 is in the first state, the pressure detection unit 5 can detect the hydraulic pressure inside the hydraulic cylinder 4 or the hydraulic system to determine the contact force between the injection unit body 1 and the gate 3. Specifically, the hydraulic system includes an oil tank 7, an oil pump 8, and a valve assembly 9 connected sequentially via an oil circuit 6. The oil cylinder 4 is connected to and controlled by the valve assembly 9. The oil pump 8 draws hydraulic oil from the oil tank 7 into the oil circuit 6 to drive the oil cylinder 4. The valve assembly 9 switches the direction of the oil circuit 6 to change the extension / retraction direction of the oil cylinder 4. The operating principle of the oil pump 8 driving the oil cylinder 4, the structure of the valve assembly 9, and the principle by which the valve assembly 9 drives the oil cylinder 4 to change direction are common knowledge in the field and do not involve improvements to this solution; therefore, they will not be elaborated upon here.

[0033] When the pressure detection unit 5 is installed on the hydraulic cylinder 4, a detection hole 10 is provided on the side wall of the cylinder barrel 24 of the hydraulic cylinder 4, and the pressure detection unit 5 is disposed in the detection hole 10. Specifically, an internal threaded bushing 11 is integrally provided on the outer side of the detection hole 10, communicating with the detection hole 10 itself for threaded connection of the pressure detection unit 5. A compression ring 12 is fixedly surrounded on the outer side of the pressure detection unit 5, and a sealing ring 13 is provided between the compression ring 12 and the internal threaded bushing 11. The sealing ring 13 is made of rubber, which can effectively improve the installation sealing of the pressure detection unit 5, thereby preventing hydraulic oil leakage in the hydraulic cylinder 4.

[0034] When the pressure detection unit 5 is installed on the oil circuit 6, the oil circuit 6 is provided with a three-way fitting 14, which is preferably a three-way pipe or an oil distribution block. The inlet 15 of the three-way fitting 14 and one of its outlets 30 are connected in series on the oil circuit 6. The pressure detection unit 5 is threaded to the other outlet 30 of the three-way fitting 14, thereby realizing the detection of oil pressure in the oil circuit 6.

[0035] To achieve feedback regulation of the jacking pressure of the hydraulic cylinder 4, a controller 16 and a drive unit 17 are sequentially coupled to the pressure detection unit 5. The controller 16 is preferably a microcontroller or PLC, and the drive unit 17 is preferably a frequency converter, but can also be an electrical control component such as a control module. The valve assembly 9 is coupled to and controlled by the controller 16. The hydraulic system also includes a power source 18 for driving the oil pump 8 and coupled to the drive unit 17. The power source 18 is preferably a motor fixed on the injection stage body 1, and its output shaft is coaxially fixed to the input shaft of the oil pump 8. The controller 16 has a preset pressure threshold, which corresponds to the contact force when the nozzle 23 and the gate 3 are joined.

[0036] To facilitate the adjustment of operating parameters such as pressure threshold, the controller 16 is also coupled to an input unit 19 that responds to external triggers to adjust the pressure threshold parameters. The input unit 19 is preferably a touch screen, which integrates a virtual keyboard that responds to external triggers, enabling both parameter input and convenient viewing of parameter changes by the user.

[0037] To facilitate monitoring of the operating position and speed of the launcher body 1, a position and speed sensor 29 coupled to the controller 16 is provided on one side of the launcher body 1. It can convert the measured operating position and speed of the launcher body 1 into a detection signal and send it to the controller 16.

[0038] like Figure 7 As shown, in order to meet the needs of different customers, the oil tank 7, power source 18 and valve assembly 9 can be set on the injection unit body 1 or installed under the worktable 28 of the injection molding machine 27.

[0039] The specific working principle is as follows: As the injection stage body 1 moves forward, the controller 16 controls the power source 18 to operate via the drive unit 17, thereby driving the oil pump 8 and controlling the valve assembly 9 to switch the oil circuit 6 in the hydraulic system to the forward operating state. This drives the oil cylinder 4 to retract, thus propelling the injection stage body 1 closer to the fixed template 2. During this process, the position and speed sensor 29 can monitor the operating position and speed of the injection stage body 1 in real time. When the nozzle 23 on the injection stage body 1 is about to contact the gate 3, the controller 16 controls the power source 18 to decelerate via the drive unit 17, causing the oil pump 8 to operate at a reduced speed. This serves both as a buffer and as a way to save energy.

[0040] When the nozzle 23 on the injection stage 1 aligns with the gate 3 on the fixed template 2 (i.e., the injection stage 1 operates in the first state), the controller 16 controls the power source 18 to continue operating, driving the injection stage 1 to apply pressure to the fixed template 2, thereby increasing the contact force between the nozzle 23 and the gate 3. Simultaneously, the controller 16 activates the pressure detection unit 5 to detect the hydraulic pressure in the cylinder 4 or the hydraulic system. If the measured hydraulic pressure value is greater than the pressure threshold, it indicates that the nozzle 23 is over-aligned with the gate 3. The controller 16 then reduces the operating speed of the power source 18 via the drive unit 17 to lower the hydraulic pressure value to the pressure threshold and controls the valve assembly 9 to lock the oil circuit 6, thereby maintaining pressure and keeping the contact force between the nozzle 23 and the gate 3 at the pressure threshold. In this state, the controller 16 initiates the injection program to inject raw material into the gate 3, effectively reducing the risk of raw material leakage.

[0041] Conversely, if the measured hydraulic pressure value is less than the pressure threshold, it indicates that the contact force between the nozzle 23 and the gate 3 is insufficient. In this case, the controller 16 increases the operating speed of the power source 18 through the drive unit 17 to raise the hydraulic pressure value back to the pressure threshold, and controls the valve assembly 9 to lock the oil circuit 6, thereby achieving pressure holding. Then, the controller 16 starts the injection program to carry out the injection process.

[0042] When the injection stage body 1 retracts, the controller 16 first terminates the injection program, and then controls the valve assembly 9 to switch the oil circuit 6 in the hydraulic system to the reverse running state, thereby driving the oil cylinder 4 to extend, and then driving the injection stage body 1 away from the fixed template 2, so that the injection stage body 1 moves to the second state.

[0043] The above control process can be implemented by means of the built-in program of the controller 16 or an equivalent analog circuit, which is common knowledge in the field and will not be described in detail here.

Claims

1. A driving mechanism for an injection molding machine, comprising an injection unit body (1), a fixed platen (2), and a gate (3) opened on the fixed platen (2), characterized in that: A hydraulic cylinder (4) is provided between the front end of the injection platform body (1) and the fixed template (2) for driving the injection platform body (1) to engage with the gate (3) in the first state and driving the injection platform body (1) away from the fixed template (2) in the second state. A hydraulic system for controlling the extension and retraction of the hydraulic cylinder (4) is connected to the hydraulic cylinder (4). A pressure detection unit (5) is provided on the hydraulic cylinder (4) or the hydraulic system. When the injection platform body (1) is in the first state, the pressure detection unit (5) can detect the hydraulic pressure inside the hydraulic cylinder (4) or the hydraulic system to determine the contact force between the injection platform body (1) and the gate (3).

2. The injection molding machine stage drive mechanism according to claim 1, characterized in that: The hydraulic system includes an oil tank (7), an oil pump (8), and a valve assembly (9) connected in sequence via an oil circuit (6). The cylinder (4) is connected to and controlled by the valve assembly (9). The oil pump (8) is used to draw hydraulic oil from the oil tank (7) into the oil circuit (6) to drive the cylinder (4) to run. The valve assembly (9) is used to switch the direction of the oil circuit (6) to change the extension and retraction direction of the cylinder (4).

3. The injection molding machine stage drive mechanism according to claim 1, characterized in that: The cylinder (4) has a detection hole (10) on the side wall of the cylinder barrel (24), and the pressure detection unit (5) is installed in the detection hole (10).

4. The injection molding machine stage drive mechanism according to claim 3, characterized in that: An internal threaded bushing (11) is provided on the outside of the detection hole (10) for the pressure detection unit (5) to be threaded.

5. The injection molding machine stage drive mechanism according to claim 4, characterized in that: The outer ring of the pressure detection unit (5) is provided with a compression ring (12), and a sealing ring (13) is provided between the compression ring (12) and the internal thread bushing (11).

6. The injection molding machine stage drive mechanism according to claim 2, characterized in that: A three-way connector (14) is provided on the oil circuit (6). The inlet (15) of the three-way connector (14) and one of its outlets (30) are connected in series on the oil circuit (6). The pressure detection unit (5) is connected to the other outlet (30) of the three-way connector (14).

7. The injection molding machine stage drive mechanism according to claim 2, characterized in that: The pressure detection unit (5) is coupled to a controller (16) and a drive unit (17) in sequence. The valve assembly (9) is coupled to and controlled by the controller (16). The hydraulic system also includes a power source (18) for driving the oil pump (8) and coupled to the drive unit (17). The controller (16) has a preset pressure threshold. When the injection stage body (1) is running in the first state, the pressure detection unit (5) can detect the hydraulic pressure in the oil cylinder (4) or the hydraulic system. If the measured hydraulic pressure value is greater than the pressure threshold, the pressure detection unit (5) can detect the hydraulic pressure in the oil cylinder (4) or the hydraulic system. If the measured hydraulic pressure is less than the pressure threshold, the controller (16) reduces the operating speed of the power source (18) through the drive unit (17) to reduce the hydraulic pressure value to the pressure threshold, and controls the valve assembly (9) to lock the oil circuit (6) to achieve pressure holding; conversely, if the measured hydraulic pressure value is less than the pressure threshold, the controller (16) increases the operating speed of the power source (18) through the drive unit (17) to increase the hydraulic pressure value back to the pressure threshold, and controls the valve assembly (9) to lock the oil circuit (6) to achieve pressure holding.

8. The injection molding machine stage drive mechanism according to claim 7, characterized in that: The drive unit (17) is a frequency converter.

9. The injection molding machine stage drive mechanism according to claim 7, characterized in that: The controller (16) is also coupled to an input unit (19) that responds to an external trigger to adjust the pressure threshold parameter.

10. The injection molding machine stage drive mechanism according to claim 1, characterized in that: The push rod (20) and cylinder (24) of the hydraulic cylinder (4) are fixed to the front side of the fixed template (2) and the main body of the firing platform (1) respectively through the hinge seat (21).

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