Gas injection device of foaming injection molding machine

Abstract

The invention relates to a gas injection device of a foaming injection molding machine, and belongs to the technical field of injection molding machines. The gas injection device comprises a gas source; a pressure reducing valve; an air inlet one-way valve; injecting air cylinders; a gas injection piston; the connecting rod mechanism is used for connecting the gas injection piston and the injection screw rod; the gas injection head is communicated with the gas storage chamber and the injection charging barrel; the gas injection one-way valve is located between the gas injection head and the gas injection cylinder, and gas in the gas storage chamber enters the injection charging barrel in a one-way mode through the gas injection one-way valve; and when the injection screw retreats in a pre-plasticized mode, the gas injection piston is driven by the connecting rod mechanism to slide in the gas injection cylinder, the volume of the gas storage chamber is compressed, after the gas pressure rises to exceed the melt pressure, the gas injection head is opened, and inert gas enters the injection charging barrel through the gas injection head. The gas injection system is simplified, the gas injection flow and pre-plasticizing of the injection screw are synchronously carried out, and the manufacturing cost of equipment is reduced.

Description

Technical Field

[0001] The present application relates to the technical field of injection molding machines, and in particular to a gas injection device for a foaming injection molding machine. Background Art

[0002] The foaming injection molding machine is a special equipment used to produce lightweight porous plastic products. It injects a foaming agent into the plastic melt to expand it in the mold to form a lightweight product with micropores inside.

[0003] Gas injection methods include physical foaming and chemical foaming. The existing physical foaming gas injection device includes a gas storage tank, a booster pump, a gas control valve, a gas flow meter (imported part), a gas flow control valve (imported part), a gas injection nozzle, a metering feedback unit and a control software. The gas injection device and the injection system of the injection molding machine are independent of each other, but they are also linked to each other, and the control is relatively complex. When the plasticizing system is rotating the screw to plasticize, the metering feedback unit accurately controls the time and flow rate of gas injection into the melt according to the flow rate, temperature, pressure and other parameters of the melt, thereby achieving uniform mixing of gas and melt and the mass ratio of gas in the melt.

[0004] Regarding the above-mentioned related technologies, the above-mentioned gas injection method guarantees the foaming effect and quality to a certain extent, but it requires multiple components to work together, and each component has its specific functions and structural requirements to ensure the accuracy and stability of the entire gas injection process, resulting in a more complex structure involving the coordination of multiple expensive components, which not only increases the manufacturing cost of the equipment, but also makes the maintenance and process debugging of the equipment more difficult, thereby affecting the popularization and promotion of this technology. Summary of the invention

[0005] In order to simplify the gas injection system and reduce the production cost of the equipment, the present application provides a gas injection device for a foaming injection molding machine.

[0006] The present application provides a gas injection device for a foaming injection molding machine. The following technical solution is adopted: A gas injection device for a foaming injection molding machine, a gas source, is used to store inert gas, The intake check valve is connected to the output end of the gas source. The gas injection cylinder is located between the gas source and the intake check valve and has a gas storage chamber for storing gas. The inert gas of the gas source enters the gas injection cylinder unidirectionally through the intake check valve. The gas injection piston is slidably installed in the gas injection cylinder. The linkage mechanism is used to connect the gas injection piston and the injection screw. The gas injection head communicates the gas storage chamber and the injection barrel. The gas injection check valve is located between the gas injection head and the gas injection cylinder. The gas in the gas storage chamber enters the injection barrel unidirectionally through the gas injection check valve. When the injection screw pre-plasticizes and retracts, the gas injection piston is driven to slide in the gas injection cylinder through the linkage mechanism, compressing the volume of the gas storage chamber, so that the inert gas is pressurized to overcome the melt pressure of the gas injection head, thereby opening the gas injection head and entering the injection barrel through the gas injection head.

[0007] By adopting the above technical solution, the gas injection device uses the linkage mechanism to transfer the movement of the injection screw to the gas injection piston, so that when the injection screw pushes the melt for plasticization, the volume of the gas storage chamber of the gas injection cylinder can be compressed synchronously, and the inert gas can automatically enter the injection barrel from pressure balance through the gas injection head, simplifying the existing gas injection system, reducing the cost, and the gas injection process is coordinated with the plasticization process, which is beneficial to the flow rate of the inert gas and the gas injection stroke, and automatically matches the flow rate of the melt and the plasticization stroke, and is uniformly mixed with the melt, without a complex control system and precise and expensive measurement and adjustment of the gas flow rate.

[0008] Optionally, the linkage mechanism includes a first connecting rod, a sliding sleeve and a second connecting rod. The two ends of the first connecting rod are respectively fixed to the injection screw and the sliding sleeve. One end of the second connecting rod is fixed to the gas injection piston, and the other end is slidably installed in the sliding sleeve. A limiting end is arranged at the end of the second connecting rod and is limited in the sliding sleeve.

[0009] By adopting the above technical solution, the structural composition of the linkage mechanism is disclosed. The linkage mechanism connects the gas injection piston and the injection screw, and can drive the gas injection piston to slide in the gas injection cylinder through this mechanism when the injection screw pre-plasticizes and retracts, compressing the volume of the gas storage chamber, so that the inert gas enters the injection barrel through the gas injection head; a limiting end is arranged at the end of the second connecting rod and is limited in the sliding sleeve, which can ensure the stability and accuracy of the gas injection piston moving with the injection screw, and further realize stable gas injection.

[0010] Optionally, a plurality of hinge parts are arranged at intervals on the first connecting rod. A hinge rod that rotates in cooperation with the hinge parts and a horizontal driving part that drives the hinge rod to move horizontally are arranged on one side of the injection barrel in a lifting manner.

[0011] By adopting the above technical solution, a plurality of hinge parts are arranged on the first connecting rod, which cooperate with the lifting hinge rod and the horizontal driving part. By the cooperation of the hinge rod and different hinge seats, the length ratio of the connecting rod, L2 / L1, is changed, so as to adjust the injection gas volume during pre-plasticization to adapt to the injection gas requirements of different products.

[0012] Optionally, the stroke of the injection cylinder is S2, the stroke of the injection screw is S1, the length of the first connecting rod from the hinge rod to the injection screw is L1, and the length of the first connecting rod from the hinge rod to the limit end is L2. 。

[0013] By adopting the above technical solution, a certain relationship is satisfied among the stroke S2 of the injection cylinder, the stroke S1 of the injection screw and the lengths of different parts of the first connecting rod, which can accurately control the sliding amount of the injection piston in the injection cylinder, so as to accurately control the amount of inert gas injected into the injection barrel by the injection cylinder, make the mass ratio of the inert gas and the melt constant, and the injection device has a simple and reliable structure.

[0014] Optionally, the diameter of the injection cylinder is d, the volume of the injection cylinder is V, and the injection gas volume of the injection cylinder is determined by the stroke S2 and the diameter d of the injection cylinder. 。

[0015] By adopting the above technical solution, the injection gas volume of the injection cylinder is determined by the stroke S2 and the diameter d of the injection cylinder, and the injection gas volume can be flexibly controlled to meet different production requirements. By replacing the injection cylinder with different outer diameters, the size of the injection gas volume can be adjusted.

[0016] Optionally, a hinge part is slidably arranged along the length direction on the first connecting rod, and a hinge rod which is rotationally matched with the hinge part is arranged on one side of the injection barrel in a lifting manner.

[0017] By adopting the above technical solution, the hinge part is slidably arranged along the length direction of the first connecting rod, so that the hinge rod drives the hinge part to move directly up and down, realizing stepless adjustment of the ratio of L2 and L1, and further adapting to the injection gas requirements of different products.

[0018] Optionally, the injection device includes a plurality of injection cylinders arranged in parallel, an injection piston is slidably installed in each injection cylinder, adjacent injection cylinders are arranged in parallel, and multiple groups of injection pistons are all fixed to the second connecting rod.

[0019] By adopting the above technical solution, another way to adjust the injection gas volume is provided. A plurality of injection cylinders arranged in parallel and in parallel work together, and cooperate with multiple groups of injection pistons fixed to the second connecting rod, which can increase the gas storage capacity and injection gas flow of the injection device.

[0020] Optionally, the gas injection head includes a gas injection head valve body, a gas injection head piston slidably mounted on the gas injection head valve body, a spring sleeved on the gas injection head piston, a gas injection shaft connected to the gas injection head piston, and a gas injection seal head sealing the end of the gas injection head valve body; A gas transmission narrow slit is formed between the gas injection shaft and the inner wall of the gas injection head valve body. The gas injection seal head is provided with a sealing inclined surface, and the gas injection head valve body is provided with a gas injection head pressure acting cavity that fits the sealing inclined surface. When the pressure in the gas storage chamber is 0.5 - 2 MPa higher than the melt pressure, the gas injection check valve is in an open state, and gas is transported from the gas storage chamber to the injection barrel.

[0021] By adopting the above technical solution, the structural composition of the gas injection head is disclosed. When the pressure in the gas storage chamber is 0.5 - 2 MPa higher than the melt pressure, the gas injection check valve opens, and gas flows from the gas storage chamber to the gas injection head valve body, pushing the gas injection head piston to slide, releasing the fit between the sealing inclined surface and the gas injection head pressure acting cavity, so that the gas can flow into the barrel along the gas transmission narrow slit. The gas transmission narrow slit has a flow-limiting effect on the melt, ensuring the stability and accuracy of the gas injection process and avoiding the situation where the melt in the injection barrel flows into the gas injection head valve body.

[0022] Optionally, it further includes a pressure maintaining assembly for maintaining the pressure of the gas injection cylinder. The pressure maintaining assembly includes a boosting check valve, a direction valve, and a boosting cylinder. Two ends of the boosting check valve are respectively communicated with the gas storage chamber and the direction valve. The direction valve controls the piston rod of the boosting cylinder, and the gas of the boosting cylinder enters the gas storage chamber unidirectionally through the boosting check valve.

[0023] By adopting the above technical solution, the setting of the pressure maintaining assembly enables the gas injection cylinder to maintain stability and high pressure, making the gas injection process more reliable and contributing to improving the product quality produced by the foam injection molding machine.

[0024] Optionally, it further includes a safety exhaust assembly. The safety exhaust assembly includes a manual exhaust valve, a safety valve, and a pressure gauge. The manual exhaust valve controls the gas discharge of the gas storage chamber. The pressure gauge is used to monitor the gas discharge pressure, and a silencer is further provided at the output end of the safety valve.

[0025] By adopting the above technical solution, the manual exhaust valve can control the gas discharge of the gas storage chamber, facilitating the gas discharge operation. The pressure gauge can monitor the gas discharge pressure to ensure the safety and controllability of the gas discharge process. The silencer can reduce the noise caused by the sudden discharge of high-pressure gas exceeding the set safety pressure, reducing the impact on the surrounding environment and personnel.

[0026] In summary, the present application includes at least one of the following beneficial technical effects: This application connects the gas injection piston and the injection screw through a linkage mechanism. When the injection screw injects, it drives the gas injection piston to inhale the gas from the gas source. When the injection screw is pre-plasticized, it drives the gas injection piston to compress the gas storage chamber so that the inert gas enters the injection barrel, simplifying the structure of the gas injection device and the complex software control. At the same time, the process is also simplified, reducing the manufacturing cost; Through the setting of the pressure holding component in this application, the required high pressure and pressure stability of the gas injection cylinder can be guaranteed, ensuring the stability of the gas injection volume and improving the foaming quality of the product; Under the action of the intake pressure of the gas injection head, the spring force, and the pressure of the injected melt in this application, there is always a pressure to close the gas injection head, ensuring the sealing performance of the gas injection head piston, the sensitivity of the gas injection head to open, and reducing the situation of melt backflow. Brief Description of the Drawings

[0027] Figure 1 is the overall structural schematic diagram of the embodiment of this application.

[0028] Figure 2 is the structural schematic diagram of the linkage mechanism of the embodiment of this application.

[0029] Figure 3 is the structural schematic diagram of the fixed bracket of the embodiment of this application.

[0030] Figure 4 is the structural schematic diagram of the hinge part and the hinge rod under stepless adjustment in the embodiment of this application.

[0031] Figure 5 is the structural schematic diagram of the gas injection head in the closed state in the embodiment of this application.

[0032] Figure 6 is the structural schematic diagram of the gas injection head in the open state in the embodiment of this application.

[0033] Figure 7 is Figure 5 the cross-sectional schematic diagram at A-A in

[0034] Figure 8 is the gas path principle schematic diagram of the pressure holding component and the safety exhaust component in the embodiment of this application.

[0035] Description of the reference numerals: 1. air source; 2. intake check valve; 3. injection cylinder; 31. air storage chamber; 4. injection piston; 5. linkage mechanism; 51. first link; 511. hinge portion; 512. strip through hole; 52. sliding sleeve; 53. second link; 531. limit end; 54. limit ring; 6. injection head; 61. injection head valve body; 611. air inlet; 612. air outlet; 6121. pressure acting chamber of the injection head; 613. first injection chamber; 614. second injection chamber; 615. annular accommodation groove; 62. injection head piston; 621. injection through hole; 63. spring; 64. injection shaft; 641. narrow gas transmission slit; 65. injection seal head; 651. sealing inclined surface; 7. injection check valve; 8. pressure maintaining assembly; 81. boosting check valve; 82. direction valve; 83. boosting cylinder; 84. intake check valve; 9. safety exhaust assembly; 91. manual exhaust valve; 92. safety valve; 93. pressure gauge; 94. silencer; 10. pressure reducing valve; 11. injection screw; 12. injection barrel; 13. fixed bracket; 131. lifting platform; 132. relief groove; 133. positioning socket; 14. hinge rod; 15. horizontal driving member. Detailed implementation manners

[0036] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. These are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Since the disclosed embodiments of the present invention can be arranged in different directions, these terms indicating directions are only for illustration and should not be regarded as limitations. For example, "upper" and "lower" are not necessarily limited to the directions opposite to or consistent with the direction of gravity. In addition, features defined with "first" and "second" may explicitly or implicitly include one or more of such features.

[0037] The following will Figure 1-8 further describe the present application in detail.

[0038] An injection device of a foam injection molding machine is disclosed in an embodiment of the present application.

[0039] Referring to Figure 1 , the injection device of the foam injection molding machine includes an air source 1, an intake check valve 2, an injection cylinder 3, an injection piston 4, a linkage mechanism 5, an injection head 6, an injection check valve 7, a pressure maintaining assembly 8, and a safety exhaust assembly 9.

[0040] The gas source 1 is an inert gas cylinder commonly used in the prior art, which stores inert gas inside. A pressure reducing valve 10 is installed at the output end of the gas source 1 to adjust the outlet pressure of the gas source 1 and stabilize the output flow rate of the gas.

[0041] The intake one-way valve 2 is arranged between the gas source 1 and the injection cylinder 3. Through the intake one-way valve 2, the inert gas of the gas source 1 enters the injection cylinder 3 unidirectionally.

[0042] The injection piston 4 is slidably installed in the injection cylinder 3, so that a gas storage chamber 31 for storing inert gas is formed between the end of the injection piston 4 and the inner cavity of the injection cylinder 3. There are two communication holes on the injection cylinder 3 that communicate with the gas storage chamber 31. One of the communication holes communicates with the intake one-way valve 2 for the input of inert gas and serves as the input hole. The other communication hole communicates with the injection head 6 for the output of inert gas and serves as the output hole.

[0043] The injection one-way valve 7 is arranged between the injection head 6 and the injection cylinder 3. Through the injection one-way valve 7, the inert gas in the injection cylinder 3 enters the injection head 6 unidirectionally. The output end of the injection head 6 is communicated with the injection barrel 12 of the injection molding machine.

[0044] Refer to Figure 2 and Figure 3 , the connecting rod mechanism 5 is used to connect the injection piston 4 and the injection screw 11 in the injection barrel 12, so that the injection screw 11 and the injection piston 4 form a linkage. When the hydraulic system controls the injection screw 11 to pre-plasticize and retreat, the injection piston 4 is driven to advance and slide in the injection cylinder 3 through the connecting rod mechanism 5, so that the volume of the gas storage chamber 31 is compressed, and the melt pressure of the inert gas injection head 6 enters the injection barrel 12 through the injection one-way valve 7 and the injection head 6, realizing the automatic injection of gas into the melt and mixing with it.

[0045] The connecting rod mechanism 5 includes a first connecting rod 51, a sliding sleeve 52 and a second connecting rod 53. One end of the first connecting rod 51 is provided with a limit ring 54 that is limit-mounted on the injection screw 11. The limit ring 54 is hinged to the first connecting rod 51. At the same time, the limit ring 54 is slidably matched with the injection screw 11, so that the rotation of the injection screw 11 does not drive the first connecting rod 51 to rotate synchronously.

[0046] The sliding sleeve 52 is a columnar sleeve arranged vertically. The other end of the first connecting rod 51 is fixedly connected to the bottom of the sliding sleeve 52. The sliding sleeve 52 has a sliding chamber along its length direction. One end of the second connecting rod 53 is provided with a limit end 531 arranged in the sliding chamber. The other end of the second connecting rod 53 is fixedly connected to the end of the injection piston 4.

[0047] In order to adjust the gas injection volume of a single injection, a plurality of hinged parts 511 are evenly spaced along the length direction of the first connecting rod 51. The hinged part 511 is annular as a whole and has through holes penetrating the end faces on both sides. A fixed bracket 13 is provided on one side of the injection barrel 12. A lifting platform 131 is provided on the fixed bracket 13 for lifting. The lifting platform 131 is provided with a hinged rod 14 for inserting into the hinged part 511. The lifting and lowering of the lifting platform 131 is achieved by a mechanism that can realize linear drive such as a cylinder and a motor. In order to make the hinged rod 14 and the hinged part 511 cooperate, a horizontal driving member 15 for driving the hinged rod 14 to move horizontally is also provided on the fixed bracket 13. The horizontal driving member 15 can be a cylinder or a linear module. Among them, a clearance groove 132 for the first connecting rod 51 to swing is also provided on the lifting platform 131. A positioning socket 133 for inserting the hinged rod 14 is provided on the other side of the clearance groove 132 relative to the hinged rod 14 , so as to improve the stability of the hinged rod 14 .

[0048] Define the stroke of the air injection cylinder 3 as S2, the stroke of the injection screw 11 as S1, the length from the hinged rod 14 to the limit ring 54 as L1, and the length from the hinged rod 14 to the limit end 531 as L2. The ratio of the stroke S2 ​​of the air injection cylinder 3 and the pre-plastic stroke S1 of the screw is determined by L2 / L1 of the first connecting rod 51, and the specific formula is as follows: .

[0049] The diameter of the gas injection cylinder 3 is defined as d, and the volume of the gas injection cylinder 3, that is, the volume of the gas storage chamber 31 is defined as V. Under a certain gas pressure, the gas injection volume of the gas injection cylinder 3 is determined by the stroke S2 ​​and the diameter d of the gas injection cylinder 3. The specific formula is as follows: .

[0050] In other embodiments, a hinged portion 511 is slidably mounted on the first connecting rod 51 along its length direction, and the first connecting rod 51 is provided with a strip-shaped through hole 512 for limiting the sliding arrangement of the hinged portion 511, and the hinged portion 511 and the hinged rod 14 are rotatably matched.

[0051] In other embodiments, the gas injection volume of a single injection can also be adjusted by replacing the gas injection cylinder 3 , and selecting a gas injection cylinder 3 with a different diameter to adjust the gas injection volume.

[0052] In other embodiments, the gas injection device includes a plurality of gas injection cylinders 3, and the plurality of gas injection cylinders 3 are arranged in parallel with each other. The gas injection pistons 4 of the plurality of gas injection cylinders 3 are all fixed at the end of the second connecting rod 53, and the output end of the gas injection cylinder 3 is connected to the gas injection head 6. The second connecting rod 53 can drive the plurality of gas injection pistons 4 to slide synchronously, thereby realizing the synchronous gas injection operation of the plurality of cylinders.

[0053] Reference Figure 4 and Figure 5, the gas injection head 6 includes a gas injection head valve body 61, a gas injection head piston 62, a spring 63, a gas injection shaft 64, and a gas injection sealing head 65. The gas injection head piston 62, the gas injection shaft 64, and the gas injection sealing head 65 are coaxially and fixedly connected. The top of the gas injection head valve body 61 has an air inlet 611 communicating with the gas injection cylinder 3, and the bottom has an air outlet 612 communicating with the injection barrel 12. Among them, the gas injection head valve body 61 is provided with a gas injection head pressure acting chamber 6121 at the air outlet 612, and the gas injection head pressure acting chamber 6121 is integrally in the shape of a horn with an opening downward. The side wall of the gas injection sealing head 65 is provided with a sealing inclined surface 651 that fits the gas injection head pressure acting chamber 6121.

[0054] The gas injection head valve body 61 is further provided with an annular accommodation groove 615 between the gas injection head pressure acting chamber 6121 and the second gas injection chamber 614. The annular accommodation groove 615 communicates with the gas transmission narrow slit 641 so that gas can be pre-stored in the annular accommodation groove 615 to facilitate the efficient and stable pushing of the gas injection sealing head 65 during gas injection.

[0055] One side of the gas injection head valve body 61 along the axial direction is provided with a first gas injection chamber 613 for the gas injection head piston 62 to slide and a second gas injection chamber 614 for the gas injection shaft 64 to slide. The outer diameter of the gas injection head piston 62 is larger than that of the gas injection shaft 64 as a whole, thereby restricting the opening degree of the gas injection head 6. The spring 63 is sleeved on the gas injection head piston 62, and the two ends are respectively abutted against the gas injection head piston 62 and the bottom wall of the first gas injection chamber 613.

[0056] The gas injection head piston 62 is provided with gas injection through holes 621 for gas to flow at intervals, and the gas injection through holes 621 and the air inlet 611 are arranged in a staggered manner. The radial cross-section of the gas injection shaft 64 is an incomplete circular surface, so that a gas transmission narrow slit 641 is formed between the side wall of the gas injection shaft 64 and the inner wall of the second gas injection chamber 614.

[0057] Before injecting gas, the gas injection sealing head 65 and the air outlet 612 are in a sealed state. At the same time, the top of the gas injection head piston 62 fits the top wall of the first gas injection chamber 613, and the gas injection head piston 62 and the first gas injection chamber 613 are also in a sealed state. When the pressure in the gas storage chamber 31 is higher than the melt pressure by 0.5 - 2 MPa under the pushing action of the gas injection head piston 62, the gas injection check valve 7 is opened under this pressure, and the gas injection head piston 62 is pushed downward, so that the gas can enter the injection barrel 12 along the first gas injection chamber 613, the gas transmission narrow slit 641, and the air outlet 612.

[0058] Refer to Figure 6, the pressure-holding assembly 8 is used to ensure the injection pressure in the injection cylinder 3, and it includes a boosting check valve 81, a directional valve 82, a boosting cylinder 83, and a suction check valve 84. Both ends of the boosting check valve 81 are connected to the gas storage chamber 31 and the directional valve 82, and the other end of the directional valve 82 is connected to the boosting cylinder 83. The gas flow direction is: from the directional valve 82 through the boosting check valve 81 to the gas storage chamber 31. The inner cavity of the boosting cylinder 83 is connected to the output end of the suction check valve 84, and the gas path between the intake directional valve 82 and the input hole of the injection cylinder 3 is connected to the input end of the suction check valve 84 to facilitate the suction of the boosting cylinder 83.

[0059] The injection pressure of the injection cylinder 3 under normal conditions is set and monitored by a pressure relay (not marked in the figure). When the gas pressure in the injection cylinder 3 is less than the set value, the directional valve 82 opens, and the boosting cylinder 83 inputs the gas along the directional valve 82 and the boosting check valve 81 into the gas storage chamber 31 until the injection pressure is boosted to the set value.

[0060] The safety exhaust assembly 9 is used to discharge the gas in the injection cylinder 3, so that when the injection molding machine stops working, the pressure in the injection cylinder 3 is balanced with the outside atmosphere, improving the service life of the injection device. The safety exhaust assembly 9 includes a manual exhaust valve 91, a safety valve 92, a pressure gauge 93, and a muffler 94. The manual exhaust valve 91 is connected to the gas storage chamber 31 and is used to discharge the high-pressure gas in the gas storage chamber 31. The safety valve 92 and the pressure gauge 93 are both arranged at the inlet end of the manual exhaust valve 91, where the safety valve 92 is used to ensure that the pressure in the injection cylinder 3 does not exceed the safety level, and the pressure gauge 93 is used to monitor the pressure before exhaust, further improving the safety of exhaust.

[0061] The implementation principle of the injection device of a foaming injection molding machine according to an embodiment of the present application is as follows: When the injection screw 11 is pre-plasticized, the injection screw 11 retreats horizontally backward. Under the action of the connecting rod mechanism 5, it drives the injection piston 4 to move forward and compresses the air pressure in the gas storage chamber 31. When the air pressure in the gas storage chamber 31 exceeds the injection check valve 7, injection starts. The gas overcomes the melt pressure at the injection head 6, causing the injection head piston 62, the injection shaft 64, and the injection seal head 65 to all slide downward, enabling the gas to enter the injection barrel 12 and mix with the melt until the injection screw 11 stops pre-plasticizing displacement, or the gas pressure in the injection cylinder 3 is lower than the melt pressure of the injection head 6, and the injection also stops synchronously; When the injection screw 11 starts to advance for injection, the piston of the injection cylinder 3 retreats, and gas is inhaled from the gas source 1 through the intake check valve 2 and supplemented to the injection cylinder 3. At this time, the directional valve 82 is in the closed state. If the gas pressure in the injection cylinder 3 is lower than the pressure set by the pressure relay, the directional valve 82 switches to the open position, and the boosting cylinder 83 opens to input gas into the gas storage chamber 31. The pressure-holding assembly 8 ensures that the injection pressure in the injection cylinder 3 reaches the set pressure; When the injection molding machine stops working, the staff manually controls the manual exhaust valve 91 to exhaust gas, reducing the time that the injection cylinder 3 is under high pressure for a long time and improving its service life.

[0062] The above are all preferred embodiments of this application, and the protection scope of this application is not limited thereby. Therefore, all equivalent changes made according to the structure, shape, and principle of this application shall be covered within the protection scope of this application.

Claims

1. An air injection device for a foaming injection molding machine, characterized in that, Comprising: A gas source (1) for storing inert gas; A pressure reducing valve (10) for setting the outlet pressure of the gas source (1); An intake check valve (2) connected to the output end of the gas source (1); An injection cylinder (3) located between the gas source (1) and the intake check valve (2), having a gas storage chamber (31) for storing gas, and the inert gas of the gas source (1) enters the injection cylinder (3) unidirectionally through the pressure reducing valve (10) and the intake check valve (2); An injection piston (4) slidably mounted in the injection cylinder (3); A linkage mechanism (5) for connecting the injection piston (4) and the injection screw (11); An injection head (6) communicating the gas storage chamber (31) and the injection barrel (12); An injection check valve (7) located between the injection head (6) and the injection cylinder (3), and the gas in the gas storage chamber (31) enters the injection barrel (12) unidirectionally through the injection check valve (7); When the injection screw (11) pre-plasticizes and retracts, the injection piston (4) is driven by the linkage mechanism (5) to slide in the injection cylinder (3), compressing the volume of the gas storage chamber (31), so that the inert gas is pressurized to overcome the melt pressure of the injection head (6), thereby opening the injection head (6) and entering the injection barrel (12) through the injection head (6).

2. The gas injection device of a foam injection molding machine according to claim 1, characterized in that, The linkage mechanism (5) includes a first connecting rod (51), a sliding sleeve (52) and a second connecting rod (53). The two ends of the first connecting rod (51) are respectively fixed to the injection screw (11) and the sliding sleeve (52). One end of the second connecting rod (53) is fixed to the injection piston (4), and the other end is slidably mounted in the sliding sleeve (52). A limiting end (531) arranged in the sliding sleeve (52) is provided at the end of the second connecting rod (53).

3. The gas injection device of a foaming injection molding machine according to claim 2, characterized in that, A plurality of hinge parts (511) are arranged at intervals on the first connecting rod (51). An articulated rod (14) rotatably cooperating with the hinge parts (511) and a horizontal driving member (15) for driving the articulated rod (14) to move horizontally are arranged on one side of the injection barrel (12) in a lifting manner.

4. The gas injection device of a foam injection molding machine according to claim 3, characterized in that, The stroke of the injection cylinder (3) is S2, the stroke of the injection screw (11) is S1, the length of the first connecting rod (51) from the articulated rod (14) to the injection screw (11) is L1, and the length of the first connecting rod (51) from the articulated rod (14) to the limiting end (531) is L2. 。 5. The gas injection device of a foam injection molding machine according to claim 4, characterized in that, The diameter of the injection cylinder (3) is d, the volume of the injection cylinder (3) is V, and the gas injection volume of the injection cylinder (3) is determined by the stroke S2 and the diameter d of the injection cylinder (3). 。 6. The gas injection device of a foam injection molding machine according to claim 2, characterized in that, The hinge parts (511) are slidably arranged along the length direction on the first connecting rod (51), and an articulated rod (14) rotatably cooperating with the hinge parts (511) is arranged on one side of the injection barrel (12) in a lifting manner.

7. The gas injection device of a foam injection molding machine according to claim 2, characterized in that, The gas injection device includes a plurality of injection cylinders (3) arranged in parallel. The injection pistons (4) are slidably mounted in the injection cylinders (3). The adjacent injection cylinders (3) are connected in parallel, and multiple groups of injection pistons (4) are all fixed to the second connecting rod (53).

8. The gas injection device of a foaming injection molding machine according to claim 1, characterized in that, The gas injection head (6) includes a gas injection head valve body (61), a gas injection head piston (62) slidably mounted on the gas injection head valve body (61), a spring (63) sleeved on the gas injection head piston (62), a gas injection shaft (64) connected to the gas injection head piston (62), and a gas injection seal head (65) sealing the end of the gas injection head valve body (61); A gas transmission narrow slit (641) for gas passage is formed between the gas injection shaft (64) and the inner wall of the gas injection head valve body (61). The gas injection seal head (65) is provided with a sealing inclined surface (651), and the gas injection head valve body (61) is provided with a gas injection head pressure acting cavity (6121) that fits the sealing inclined surface (651). When the pressure in the gas storage chamber (31) is 0.5 - 2 MPa higher than the melt pressure, the gas injection one-way valve (7) and the gas injection head (6) are in an open state, and gas is transported from the gas storage chamber (31) to the injection barrel (12).

9. The gas injection device of a foaming injection molding machine according to claim 1, characterized in that, It further includes a pressure maintaining assembly (8) for maintaining the gas injection pressure of the gas injection cylinder (3). The pressure maintaining assembly (8) includes a boosting one-way valve (81), a directional valve (82), a boosting cylinder (83), and a suction one-way valve (84). The two ends of the boosting one-way valve (81) are respectively communicated with the gas storage chamber (31) and the directional valve (82), and the directional valve (82) controls the boosting action of the boosting cylinder (83); During boosting, the directional valve (82) is opened, and the boosting gas enters the gas storage chamber (31) through the directional valve (82) and the boosting one-way valve (81); After boosting, the directional valve (82) is closed, and the boosting cylinder (83) sucks gas from the gas source (1) through the suction one-way valve (84) to achieve resetting.

10. The gas injection device of a foaming injection molding machine according to claim 1, characterized in that, It further includes a safety exhaust assembly (9). The safety exhaust assembly (9) includes a manual exhaust valve (91), a safety valve (92), and a pressure gauge (93). The manual exhaust valve (91) controls the gas discharge of the gas storage chamber (31), and the pressure gauge (93) is used to monitor the pressure before gas discharge; A silencer (94) is further provided at the output end of the safety valve (92).

Images