Hydraulic system and injection molding machine

Abstract

The hydraulic system is applied to an injection molding machine and comprises a mold locking control loop and a glue injection control loop, the mold locking control loop comprises a first direction valve, a second direction valve, a third direction valve, a fourth direction valve, a first cartridge valve, an overflow valve and a safety valve, the pressure maintaining device is arranged to lock the mold at preset pressure and maintain the pressure; and the glue injection control loop is connected with the mold locking control loop, comprises a hydraulic lock, a plurality of direction valves, a second cartridge valve and a proportional overflow valve, and is set to control the density of molten glue through proportional molten glue back pressure. The injection molding machine solves the problem of low production efficiency of plastic products of an injection molding machine in the prior art.

Description

Technical Field

[0001] The present application relates to the technical field of injection molding machines, and in particular to a hydraulic system and an injection molding machine. Background Art

[0002] Injection molding machines play an important role in national production. They can efficiently and mass-produce various types of plastic products to meet the needs of many fields such as automobiles, electronics, and home appliances. They improve production efficiency, ensure the stability and consistency of product quality, reduce production costs, promote the development of the plastic products industry, and play an important role in promoting economic growth in related industries.

[0003] In recent years, the production efficiency of plastic products by injection molding machines has been continuously improved, but there are still problems such as long production time and low production efficiency of plastic products. Summary of the invention

[0004] The main purpose of the present application is to provide a hydraulic system and an injection molding machine to solve the problem of low plastic product production efficiency of the injection molding machine in the prior art.

[0005] According to one aspect of the present application, a hydraulic system is provided, which is applied to an injection molding machine, and includes: a mold locking control circuit and a glue injection control circuit, wherein the mold locking control circuit includes: a first directional valve, a second directional valve, a third directional valve, a fourth directional valve, a first cartridge valve, a relief valve and a safety valve, which are configured to lock the mold at a preset pressure and maintain the pressure; wherein the A port and the B port of the second directional valve are respectively connected to the oil inlet and the oil return port of the mold adjustment motor; the relief valve and the fourth directional valve are pilot valves of the first cartridge valve; the P port and the A port of the safety valve are connected to the rodless cavity of the mold locking cylinder, and the T port and the B port of the safety valve are connected to the A port of the third directional valve; the B port of the third directional valve is connected to the rod cavity of the mold locking cylinder; the glue injection control circuit is connected to the mold locking control circuit, and includes: a hydraulic lock, multiple directional valves, a second cartridge valve and a proportional relief valve, which are configured to control the melt density by proportional melt back pressure.

[0006] Optionally, when the safety valve is not powered, its valve core is in a closed state; when the safety valve is powered, its P port is connected to the B port, its T port is connected to the A port, and its valve core is in an open state.

[0007] Optionally, when the solenoid 2YA of the third directional valve and the solenoid 4YA of the safety valve are powered, the valve core of the first cartridge valve is closed and the valve core of the safety valve is opened, forming a differential speed-increasing circuit, and the oil enters the rodless chamber of the locking cylinder through the third directional valve and the safety valve to perform a rapid mold closing action; when approaching the set end position, the solenoid 3YA of the fourth directional valve is powered, the valve core of the first cartridge valve is opened, and a slow mold closing action is performed.

[0008] Optionally, when the solenoid 1YA of the third directional valve and the solenoid 5YA of the first directional valve are powered, the oil enters the rod chamber of the locking cylinder through the third directional valve, and the oil in the rodless chamber of the locking cylinder is quickly depressurized through the first directional valve to achieve a rapid mold opening action; when the solenoid 3YA of the fourth directional valve is powered, the valve core of the first cartridge valve is opened, generating oil return back pressure, and performing a slow mold opening action.

[0009] Optionally, when the second directional valve controls the mold adjusting motor to rotate forward, the mold adjusting forward action is realized; when the second directional valve controls the mold adjusting motor to rotate reversely, the mold adjusting backward action is realized.

[0010] Optionally, the injection control circuit includes multiple directional valves including: a fifth directional valve, a sixth directional valve and a seventh directional valve, wherein the fifth directional valve is connected to the hydraulic lock, and the A port of the fifth directional valve is connected to the rod chamber of the injection cylinder, and the B port is connected to the rodless chamber of the injection cylinder; the A port of the sixth directional valve is connected to the rodless chamber of the injection cylinder, the B port is connected to the rod chamber of the injection cylinder, and the B port of the sixth directional valve is connected to the lower oil port of the second cartridge valve, and the side oil port of the second cartridge valve is connected to the oil tank; the seventh directional valve and the proportional relief valve are the pilot valves of the second cartridge valve.

[0011] Optionally, when the seventh directional valve is not powered and the electromagnet 3YA of the sixth directional valve is powered, the valve core of the second cartridge valve is closed, and the oil enters the rod chamber of the injection cylinder to push the piston to perform injection.

[0012] Optionally, when the seventh directional valve is not powered and the electromagnet 4YA of the sixth directional valve is powered, the valve core of the second cartridge valve is closed, and the oil enters the rodless chamber of the injection cylinder to push the piston to perform an injection-retraction action.

[0013] Optionally, when the fifth directional valve is not powered, no oil passes through the hydraulic lock and the shooting cylinder is locked; when the electromagnet 1YA of the fifth directional valve is powered, the oil enters the rodless chamber of the shooting cylinder, and the oil pushes the piston of the shooting cylinder to move toward the rod chamber of the shooting cylinder, thereby achieving the retreat of the injection seat; when the electromagnet 2YA of the sixth directional valve is powered, the oil enters the rod chamber of the shooting cylinder, and the oil pushes the piston of the shooting cylinder to move toward the rodless chamber of the shooting cylinder, thereby achieving the advancement of the injection seat.

[0014] Optionally, when the melt action is being performed, the screw retreats under the action of the front material pressure, the electromagnet 5YA of the seventh directional valve is energized, the valve core of the second cartridge valve is opened, and the oil returns to the oil tank after passing through the second cartridge valve, the seventh directional valve and the proportional relief valve; the proportional relief valve is set to perform stepless adjustment of the melt back pressure.

[0015] According to another aspect of the present application, an injection molding machine is also provided, comprising the above hydraulic system.

[0016] In the present application, a hydraulic system for an injection molding machine is provided, which focuses on optimizing the design of the clamping hydraulic control circuit of a small hinged injection molding machine, thereby improving the opening and closing speeds while ensuring the clamping accuracy, thereby shortening the production time and improving production efficiency. The system has the characteristics of good versatility and fast response speed. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings: Figure 1 is a schematic diagram of a hydraulic system applied to an injection molding machine according to an embodiment of the present application; Figure 2 is a schematic diagram of a clamping control circuit of a hydraulic system according to an embodiment of the present application; Figure 3 It is a schematic diagram of a glue injection control circuit of a hydraulic system according to an embodiment of the present application. DETAILED DESCRIPTION

[0018] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0019] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0020] Unless otherwise specifically stated, the relative arrangement, numerical expressions and numerical values ​​of the parts and steps set forth in these embodiments do not limit the scope of the present application. At the same time, it should be understood that, for ease of description, the sizes of the various parts shown in the accompanying drawings are not drawn according to the actual proportional relationship. The technology, methods and equipment known to those of ordinary skill in the relevant art may not be discussed in detail, but in appropriate cases, the technology, methods and equipment should be considered as a part of the authorization specification. In all examples shown and discussed here, any specific value should be interpreted as being merely exemplary, rather than as a limitation. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters represent similar items in the following drawings, and therefore, once a certain item is defined in an accompanying drawing, it does not need to be further discussed in subsequent drawings.

[0021] In order to better understand the embodiments of the present application, the technical terms involved in the embodiments of the present application are explained as follows: Injection molding machine, also known as injection molding machine or injection machine, is a main molding equipment used to make thermoplastics or thermosetting plastics into plastic products of various shapes through plastic molding molds. Figure 1 is a schematic diagram of a hydraulic system of an injection molding machine according to an embodiment of the present application, and the hydraulic system is applied to an injection molding machine, such as Figure 1 As shown, the hydraulic system includes: a mold locking control circuit 1 and a glue injection control circuit 2.

[0022] Hydraulic systems are widely used systems in industry and machinery that use the pressure of a liquid (usually oil) to transfer power and energy. Hydraulic systems are widely used because of their ability to provide high force, precise control, and reliability in a variety of environments. The working principle of hydraulic systems is based on Pascal's Law, which states that the pressure applied to a stationary fluid in a closed system is equal in all directions. This means that in a hydraulic system, a force applied to a small area is proportionally amplified when it is transferred to a large area through the liquid.

[0023] In the process of injection molding, injection control is a very critical link, which directly affects the quality and production efficiency of the final product. The injection control circuit is mainly responsible for injecting the molten plastic into the mold cavity at a predetermined pressure and speed.

[0024] The clamping control circuit is an important part of the injection molding machine. It is responsible for ensuring that the mold remains closed during the injection and holding process and can withstand high pressure. The clamping force directly affects the quality and production efficiency of the product.

[0025] The hydraulic system in the embodiment of the present application focuses on optimizing the clamping control circuit and injection control circuit of a small-sized hinged injection molding machine, and can be applied to most high-speed small-sized hinged injection molding machines, with high system integration, compact structure, and convenient later maintenance. Detailed description is given below.

[0026] Figure 2 is a schematic diagram of a clamping control circuit of a hydraulic system according to an embodiment of the present application, such as Figure 2 As shown, the mold locking control circuit 1 includes: a first directional valve 101, a second directional valve 102, a third directional valve 104, a fourth directional valve 105, a first cartridge valve 103, an overflow valve 106 and a safety valve 107, which are configured to lock the mold at a preset pressure and maintain the pressure.

[0027] Directional valves (also called reversing valves) are very important control components in hydraulic and pneumatic systems. They are used to change the direction of the fluid, thereby controlling the action of the actuator (such as a cylinder or motor).

[0028] The cartridge valve is a compact hydraulic control valve, usually used in a multi-way block or valve block integrated in a hydraulic system. It can achieve multiple functions such as direction control, pressure control, flow control, etc. Common functions include reversing, overflow, pressure reduction, sequential action, etc.

[0029] The relief valve is a pressure control valve in the hydraulic system. Its main function is to limit the maximum working pressure of the system and protect the system from damage due to overpressure.

[0030] The safety valve is an important protective device used to prevent the pressure in the hydraulic or pneumatic system from exceeding the set safety limit. When the system pressure exceeds the preset value, the safety valve will automatically open and release excess fluid (oil or gas), thereby reducing the system pressure and preventing equipment damage or safety accidents.

[0031] like Figure 2 As shown, the A port and the B port of the second directional valve 102 are respectively connected to the oil inlet and the oil return port of the mold adjustment motor; the overflow valve 106 and the fourth directional valve 105 are the pilot valves of the first cartridge valve 103; the P port and the A port of the safety valve 107 are connected to the rodless cavity of the clamping cylinder, and the T port and the B port of the safety valve 107 are connected to the A port of the third directional valve 104; the B port of the third directional valve 104 is connected to the rod cavity of the clamping cylinder.

[0032] The clamping cylinder is one of the key components in the injection molding machine. Its main function is to provide sufficient clamping force during the injection molding process to ensure that the mold remains closed under high pressure. The design and operation of the clamping cylinder are crucial to ensuring product quality, mold life and production efficiency.

[0033] According to an optional embodiment of the present application, when the safety valve 107 is not powered, its valve core is in a closed state; when the safety valve 107 is powered, its P port is connected to the B port, and its T port is connected to the A port, and its valve core is in an open state.

[0034] When the safety valve 107 is not powered, the valve core inside it is in a closed state. At this moment, if the pressure in the system exceeds a predetermined value, the oil cannot release the pressure through this valve because the valve core is closed.

[0035] When the safety valve 107 is powered, port P will be connected to port B, and port T will be connected to port A. In this way, the high-pressure oil from port P can flow to port B, and the oil in port A can return to the tank through port T. This process allows the oil to flow under certain conditions, such as when it is necessary to unload the pressure or change the direction of the oil circuit.

[0036] The mold locking control circuit in the hydraulic system provided in the present application adopts a self-locking safety valve, so that it can cut off the oil circuit in both the mold opening and mold closing stages to protect the safety of the operator.

[0037] According to another optional embodiment of the present application, when the electromagnet 2YA of the third directional valve 104 and the electromagnet 4YA of the safety valve 107 are powered, the valve core of the first cartridge valve 103 is closed and the valve core of the safety valve 107 is opened, forming a differential speed-increasing circuit, and the oil enters the rodless chamber of the locking cylinder through the third directional valve 104 and the safety valve 107 to perform a rapid mold closing action; when approaching the set end position, the electromagnet 3YA of the fourth directional valve 105 is powered, and the valve core of the first cartridge valve 103 is opened to perform a slow mold closing action.

[0038] The high-pressure oil enters the rodless chamber of the clamping cylinder through the third directional valve 104 and the already opened safety valve 107. The pressure in the rodless chamber of the clamping cylinder increases, pushing the piston to move quickly. The oil in the rod chamber of the clamping cylinder flows back to the rodless chamber through the one-way valve, forming a differential circuit, further accelerating the piston movement speed. This configuration takes advantage of the area difference between the two chambers, allowing the piston to move forward at a faster speed.

[0039] When approaching the set end position, the electromagnet 3YA of the fourth directional valve 105 is energized. The valve core of the first cartridge valve 103 opens under the pilot action. At this time, the high-pressure oil no longer flows directly into the rodless chamber through the safety valve 107, but enters after being regulated by the first cartridge valve 103, thereby reducing the pressure or flow supplied to the rodless chamber. As a result, the piston changes from fast movement to a slower speed for final positioning or pressurization operation, that is, slow mold closing action.

[0040] The hydraulic system provided in the present application can achieve zero back pressure control in the mold clamping control circuit, and perform full differential control in the mold clamping stage, so as to achieve the purpose of increasing the mold clamping speed. The mold clamping of general small-scale hinged injection molding machines is divided into three or more stages of control, most of which are slow mold clamping first, then fast mold clamping, and finally slow control at the end of the mold clamping stage. The mold clamping control circuit in the embodiment of the present application can perform zero back pressure control through the pilot valve at the beginning of the mold clamping stage, and perform fast differential in combination with the one-way valve. At the end of the mold clamping stage, the pilot valve is used to add back pressure to reduce the speed of the differential, so as to achieve the slow control required at the end of the mold clamping stage. In the mold opening stage, the first section is first depressurized by the directional valve, and the remaining oil in the second section can flow back to the main oil circuit through the safety valve.

[0041] The clamping control circuit in the hydraulic system provided in the present application has the advantage of fast clamping speed, which can realize rapid differential movement throughout the clamping process, reduce machine cycle time, and improve production efficiency.

[0042] In some optional embodiments of the present application, when the electromagnet 1YA of the third directional valve 104 and the electromagnet 5YA of the first directional valve 101 are powered, the oil enters the rod chamber of the locking cylinder through the third directional valve 104, and the oil in the rodless chamber of the locking cylinder is quickly depressurized through the first directional valve 101, thereby realizing a rapid mold opening action; when the electromagnet 3YA of the fourth directional valve 105 is powered, the valve core of the first cartridge valve 103 is opened, generating oil return back pressure, and performing a slow mold opening action.

[0043] When the electromagnet 1YA of the third directional valve 104 is energized and the electromagnet 5YA of the first directional valve 101 is energized, the high-pressure oil enters the rod chamber of the mold-locking oil cylinder through the third directional valve 104, pushing the piston to move backward (i.e., in the mold-opening direction). The oil in the rodless chamber of the mold-locking oil cylinder directly returns to the oil tank through the first directional valve 101 that has been switched to a state, achieving rapid pressure relief. In this configuration, since the oil in the rodless chamber of the mold-locking oil cylinder can be quickly discharged without encountering significant resistance, a rapid mold opening action can be achieved.

[0044] When the mold opening speed needs to be slowed down, the electromagnet 3YA of the fourth directional valve 105 is energized. The valve core of the first cartridge valve 103 is opened, but a certain back pressure is introduced at this time. This back pressure is generated by the first cartridge valve 103 adjusting the oil return path, so that the oil in the rodless chamber of the clamping cylinder encounters resistance when it is discharged, thereby slowing down the movement speed of the piston and realizing a slow mold opening action.

[0045] To further adjust the required back pressure level, this can be achieved by adjusting the pressure setting value of the relief valve 106. The relief valve 106 here plays a role in limiting the maximum back pressure, ensuring that a safe working pressure range can be maintained even during slow mold opening, and the function of zero back pressure during mold opening can be achieved.

[0046] The above design allows the system to first execute most of the mold opening stroke at a higher speed, and then automatically switch to a slower speed when approaching the end point, so as to accurately control the final position and reduce impact. This can achieve the technical effect of protecting the mold and improving processing accuracy.

[0047] The clamping control circuit in the hydraulic system provided by the present application has the advantage of stable mold opening, which reduces hydraulic shock by releasing pressure before mold opening. This control method can ensure the stability of the machine during mold opening, reduce oil return shock, and make mold opening smoother.

[0048] In some other optional embodiments of the present application, when the second directional valve 102 controls the mold adjusting motor to rotate forward, the mold adjusting forward action is realized; when the second directional valve 102 controls the mold adjusting motor to rotate reversely, the mold adjusting backward action is realized.

[0049] The mold adjustment motor is an important component used to adjust the mold thickness in the injection molding machine. During the injection molding process, the thickness of the mold may need to be adjusted according to different product and process requirements. The mold adjustment motor achieves precise adjustment of the mold thickness by driving the mold moving mechanism (usually a screw or a gear rack mechanism).

[0050] In the embodiment of the present application, the second directional valve 102 is used in the injection molding machine to control the forward and reverse rotation of the mold adjustment motor, thereby adjusting the mold thickness (i.e., the mold adjustment forward and backward movements). The injection molding machine can flexibly adjust the mold closing thickness, ensuring that each mold closing can reach the optimal state, thereby improving production efficiency and product quality.

[0051] Figure 3 is a schematic diagram of a glue injection control circuit of a hydraulic system according to an embodiment of the present application, such as Figure 3 As shown, the injection control circuit 2 is connected to the mold locking control circuit 1, and includes: a hydraulic lock 201, a plurality of directional valves, a second cartridge valve 204 and a proportional relief valve 206, which are configured to control the melt density by proportional melt back pressure.

[0052] A hydraulic lock is a device used to keep an actuator (such as a cylinder or motor) in position in a hydraulic system. It prevents movement by blocking the flow of oil within the actuator, thus ensuring that the system remains stable when no action is required.

[0053] A proportional relief valve is a pressure control valve used in hydraulic systems that can adjust the system pressure based on an input electrical signal (usually current or voltage). Unlike traditional relief valves, proportional relief valves can achieve stepless pressure regulation, providing more precise and flexible pressure control.

[0054] like Figure 3As shown, the injection control circuit 2 includes multiple directional valves including: a fifth directional valve 202, a sixth directional valve 203 and a seventh directional valve 205, wherein the fifth directional valve 202 is connected to the hydraulic lock 201, and the A port of the fifth directional valve 202 is connected to the rod chamber of the injection cylinder, and the B port is connected to the rodless chamber of the injection cylinder; the A port of the sixth directional valve 203 is connected to the rodless chamber of the injection cylinder, the B port is connected to the rod chamber of the injection cylinder, and the B port of the sixth directional valve 203 is connected to the lower oil port of the second cartridge valve 204, and the side oil port of the second cartridge valve 204 is connected to the oil tank; the seventh directional valve 205 and the proportional relief valve 206 are the pilot valves of the second cartridge valve 204.

[0055] The injection cylinder (also called the injection seat moving cylinder or injection unit moving cylinder) is an important component of the injection molding machine. Its main function is to move the injection unit (including the screw, barrel and nozzle, etc.) during the injection process to achieve precise injection position control.

[0056] According to an optional embodiment of the present application, when the seventh directional valve 205 is not powered and the electromagnet 3YA of the sixth directional valve 203 is powered, the valve core of the second cartridge valve 204 is closed, and the oil enters the rod chamber of the injection cylinder to push the piston to perform injection.

[0057] The main function of the injection cylinder (also called injection cylinder or injection cylinder) is to push the screw forward during the injection molding process and inject the molten plastic into the mold.

[0058] After the sixth directional valve 203 is switched, the high-pressure oil enters the rod chamber of the injection cylinder through the sixth directional valve 203. Since the valve core of the second cartridge valve 204 is closed, the oil in the rodless chamber of the injection cylinder cannot flow out through the second cartridge valve 204. The oil in the rodless chamber of the injection cylinder is forced to be discharged through the sixth directional valve 203 and returned to the oil tank. The high-pressure oil pushes the piston of the injection cylinder to move toward the rodless chamber, thereby performing the injection action.

[0059] This setting ensures that the oil can only drive the piston to inject glue in one direction, while allowing the oil in the other direction to flow back to the oil tank freely. This design helps to improve the efficiency and control accuracy of the injection process.

[0060] According to another optional embodiment of the present application, when the seventh directional valve 205 is not powered and the electromagnet 4YA of the sixth directional valve 203 is powered, the valve core of the second cartridge valve 204 is closed, and the oil enters the rodless chamber of the injection cylinder, pushing the piston to perform the injection-retraction action.

[0061] After the sixth directional valve 203 is switched, the high-pressure oil enters the rodless chamber of the injection cylinder through the sixth directional valve 203. Since the valve core of the second cartridge valve 204 is closed, the oil in the rod chamber of the injection cylinder cannot flow out through the second cartridge valve 204. The oil in the rod chamber of the injection cylinder is forced to be discharged through the sixth directional valve 203 and returned to the oil tank. The high-pressure oil pushes the piston of the injection cylinder to move toward the rod chamber, thereby performing the ejection action.

[0062] The above arrangement ensures that the oil can drive the piston from the rodless chamber side of the injection cylinder to eject and retract, while allowing the oil on the rod chamber side to flow back freely to the tank. This design helps to achieve fast and controlled ejection, which is very important for equipment such as injection molding machines because it can help reduce cycle time and improve production efficiency.

[0063] In some optional embodiments of the present application, when the fifth directional valve 202 is not powered, no oil passes through the hydraulic lock 201, and the shooting cylinder is locked; when the electromagnet 1YA of the fifth directional valve 202 is powered, the oil enters the rodless chamber of the shooting cylinder, and the oil pushes the piston of the shooting cylinder to move toward the rod chamber of the shooting cylinder, thereby realizing the retreat of the injection seat; when the electromagnet 2YA of the sixth directional valve 203 is powered, the oil enters the rod chamber of the shooting cylinder, and the oil pushes the piston of the shooting cylinder to move toward the rodless chamber of the shooting cylinder, thereby realizing the advancement of the injection seat.

[0064] When the fifth directional valve 202 is de-energized, no oil can enter or leave the shooting cylinder through the fifth directional valve 202. Since there is no oil flow, the hydraulic lock 201 will maintain its current state, preventing the oil in the shooting cylinder from moving, thereby locking the shooting cylinder in the current position.

[0065] When the electromagnet 1YA of the fifth directional valve 202 is energized, the high-pressure oil enters the rodless chamber of the shooting cylinder through the fifth directional valve 202. The oil pushes the piston of the shooting cylinder to move toward the rod chamber, realizing the backward movement of the injection seat. The oil in the rod chamber of the shooting cylinder is discharged through the fifth directional valve 202 and returns to the oil tank.

[0066] When the electromagnet 2YA of the sixth directional valve 203 is energized, the high-pressure oil enters the rod chamber of the shooting cylinder through the sixth directional valve 203. The oil pushes the piston of the shooting cylinder to move toward the rodless chamber, realizing the forward movement of the injection seat. The oil in the rodless chamber of the shooting cylinder is discharged through the sixth directional valve 203 and returns to the oil tank.

[0067] The above configuration enables the system to lock the position of the injection cylinder when necessary, and can quickly and accurately control the forward and backward movement of the injection seat, ensuring accurate positioning and efficient operation during the injection process.

[0068] In some other optional embodiments of the present application, when the melt action is performed, the screw retreats under the action of the front material pressure, the electromagnet 5YA of the seventh directional valve 205 is energized, the valve core of the second cartridge valve 204 is opened, and the oil returns to the oil tank after passing through the second cartridge valve 204, the seventh directional valve 205 and the proportional relief valve 206; the proportional relief valve 206 is configured to perform stepless adjustment on the melt back pressure.

[0069] When the electromagnet 5YA of the seventh directional valve 205 is energized, the valve core of the second cartridge valve 204 opens, allowing oil to pass through, which provides an oil return path for the shooting cylinder or related actuators.

[0070] When the seventh directional valve 205 is energized, the oil can flow out of the actuator (such as the shooting cylinder) and pass through the valve. The proportional relief valve 206 can adjust the pressure on the oil return path as needed, thereby achieving adjustable back pressure. The proportional relief valve is usually controlled by an electrical signal, and its opening pressure can be adjusted very accurately, thereby achieving continuous and stepless regulation of the back pressure.

[0071] Back pressure helps maintain the uniformity and consistency of the molten plastic, prevents the generation of bubbles, and in some cases can also help improve the plasticization quality. By changing the electrical signal applied to the proportional relief valve 206, its opening pressure can be continuously adjusted, and the required back pressure value can be set by the control system.

[0072] The injection circuit in the hydraulic system provided in the present application controls the density of the molten glue by proportional molten glue back pressure.

[0073] The embodiment of the present application also provides an injection molding machine, which includes the above-mentioned hydraulic system, and thus the injection molding machine includes all the technical effects of the above-mentioned hydraulic system. Since the technical effects of the hydraulic system have been described in detail above, they will not be repeated here.

[0074] For ease of description, spatially relative terms such as "above", "above", "on the upper surface of", "above", etc. may be used herein to describe the spatial positional relationship between a device or feature and other devices or features as shown in the figure. It should be understood that spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation described in the figure. For example, if the device in the accompanying drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below other devices or structures". Thus, the exemplary term "above" may include both "above" and "below". The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatially relative descriptions used herein are interpreted accordingly.

[0075] In addition, it should be noted that the use of terms such as "first" and "second" to limit components is only for the convenience of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore cannot be understood as limiting the scope of protection of this application.

[0076] The above are only preferred embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A hydraulic system, characterized in that: The hydraulic system is applied to an injection molding machine and comprises: a mold clamping control circuit (1) and a glue injection control circuit (2), wherein: The mold locking control circuit (1) comprises: a first directional valve (101), a second directional valve (102), a third directional valve (104), a fourth directional valve (105), a first cartridge valve (103), a relief valve (106) and a safety valve (107), and is configured to lock the mold at a preset pressure and maintain the pressure; Wherein, the A port and the B port of the second directional valve (102) are respectively connected to the oil inlet and the oil return port of the mold adjustment motor; the overflow valve (106) and the fourth directional valve (105) are pilot valves of the first cartridge valve (103); the P port and the A port of the safety valve (107) are connected to the rodless cavity of the mold locking cylinder, and the T port and the B port of the safety valve (107) are connected to the A port of the third directional valve (104); the B port of the third directional valve (104) is connected to the rod cavity of the mold locking cylinder; The injection control circuit (2) is connected to the mold locking control circuit (1), and comprises: a hydraulic lock (201), a plurality of directional valves, a second cartridge valve (204) and a proportional relief valve (206), and is configured to control the density of the molten glue by proportional molten glue back pressure; The seventh directional valve (205) and the proportional relief valve (206) among the multiple directional valves included in the injection control circuit (2) are pilot valves of the second cartridge valve (204); When the glue is melted, the screw moves backward under the action of the material pressure at the front end, the electromagnet 5YA of the seventh directional valve (205) is powered, the valve core of the second cartridge valve (204) is opened, and the oil returns to the oil tank after passing through the second cartridge valve (204), the seventh directional valve (205) and the proportional relief valve (206); The proportional relief valve (206) is configured to perform stepless regulation on the back pressure of the molten plastic.

2. The hydraulic system according to claim 1, characterized in that: When the safety valve (107) is not powered, its valve core is in a closed state; When the safety valve (107) is powered, its P port is connected to its B port, its T port is connected to its A port, and its valve core is in an open state.

3. The hydraulic system according to claim 1, characterized in that: When the electromagnet 2YA of the third directional valve (104) and the electromagnet 4YA of the safety valve (107) are powered, the valve core of the first cartridge valve (103) is closed and the valve core of the safety valve (107) is opened, forming a differential speed-increasing circuit, and the oil enters the rodless chamber of the clamping cylinder through the third directional valve (104) and the safety valve (107), thereby performing a rapid clamping action; When approaching the set end position, the electromagnet 3YA of the fourth directional valve (105) is powered, and the valve core of the first cartridge valve (103) is opened to perform a slow mold closing action.

4. The hydraulic system according to claim 1, characterized in that: When the electromagnet 1YA of the third directional valve (104) and the electromagnet 5YA of the first directional valve (101) are powered, oil enters the rod chamber of the mold locking cylinder through the third directional valve (104), and the oil in the rodless chamber of the mold locking cylinder is quickly depressurized through the first directional valve (101), thereby realizing a rapid mold opening action; When the electromagnet 3YA of the fourth directional valve (105) is powered, the valve core of the first cartridge valve (103) opens, generating oil return back pressure and performing a slow mold opening action.

5. The hydraulic system according to claim 1, characterized in that: When the second directional valve (102) controls the mold adjustment motor to rotate forward, a mold adjustment forward action is achieved; When the second directional valve (102) controls the mold adjustment motor to rotate in reverse, the mold adjustment retraction action is achieved.

6. The hydraulic system according to claim 1, characterized in that: The injection control circuit (2) includes a plurality of directional valves including: a fifth directional valve (202), a sixth directional valve (203) and a seventh directional valve (205), wherein: The fifth directional valve (202) is connected to the hydraulic lock (201), and the port A of the fifth directional valve (202) is connected to the rod chamber of the shooting cylinder, and the port B is connected to the rodless chamber of the shooting cylinder; The A port of the sixth directional valve (203) is connected to the rodless chamber of the injection cylinder, and the B port is connected to the rod chamber of the injection cylinder. The B port of the sixth directional valve (203) is connected to the lower oil port of the second cartridge valve (204), and the side oil port of the second cartridge valve (204) is connected to the oil tank.

7. The hydraulic system according to claim 6, characterized in that: When the seventh directional valve (205) is not powered and the electromagnet 3YA of the sixth directional valve (203) is powered, the valve core of the second cartridge valve (204) is closed, and oil enters the rod chamber of the injection cylinder to push the piston to perform injection.

8. The hydraulic system according to claim 6, characterized in that: When the seventh directional valve (205) is not powered and the electromagnet 4YA of the sixth directional valve (203) is powered, the valve core of the second cartridge valve (204) is closed, and oil enters the rodless chamber of the injection cylinder, pushing the piston to perform an injection-retraction action.

9. The hydraulic system according to claim 6, characterized in that: When the fifth directional valve (202) is not powered, no oil flows through the hydraulic lock (201), and the shooting cylinder is locked; When the electromagnet 1YA of the fifth directional valve (202) is powered, oil enters the rodless chamber of the shooting cylinder, and the oil pushes the piston of the shooting cylinder to move toward the rod chamber of the shooting cylinder, thereby achieving the backward movement of the injection seat; When the electromagnet 2YA of the sixth directional valve (203) is powered, oil enters the rod chamber of the shooting cylinder, and the oil pushes the piston of the shooting cylinder to move toward the rodless chamber of the shooting cylinder, thereby moving the injection seat forward.

10. An injection molding machine, characterized in that: A hydraulic system comprising any one of claims 1 to 9.

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