Gas injection device of foam injection molding machine

Abstract

The present application relates to a gas injection device for a foaming injection molding machine, and belongs to the technical field of injection molding machines. The gas injection device includes a gas source; a pressure reducing valve; an air inlet check valve; an injection cylinder; an injection piston; a connecting rod mechanism for connecting the injection piston and the injection screw; an injection head for connecting the gas storage chamber and the injection barrel; an injection check valve located between the injection head and the injection cylinder, and the gas in the gas storage chamber enters the injection barrel in one direction through the injection check valve; when the injection screw is pre-molded and retreats, the injection piston is driven to slide in the injection cylinder by the connecting rod mechanism, compressing the volume of the gas storage chamber. After the air pressure rises to a level exceeding the melt pressure, the injection head opens, and the inert gas enters the injection barrel through the injection head. The present application simplifies the gas injection system, and realizes the synchronization of the gas injection flow and the pre-molding of the injection screw, thereby reducing the manufacturing cost of the equipment.

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, causing it to expand and form in the mold, forming a lightweight product with micropores inside.

[0003] Gas injection methods include physical foaming and chemical foaming. Existing physical foaming gas injection equipment includes a gas storage tank, a booster pump, a gas control valve, a gas flow meter (imported), a gas flow control valve (imported), a gas injection nozzle, a metering feedback unit, and control software. The gas injection system and the injection molding machine's injection system are independent of each other but interconnected, making control relatively complex. While the plasticizing system rotates the screw to plasticize, the metering feedback unit precisely controls the timing and flow rate of gas injection into the melt based on parameters such as the melt's flow rate, temperature, and pressure, thereby achieving uniform mixing of the gas and melt and the gas mass ratio 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 requires multiple components to work together, 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 foam injection molding machine.

[0006] This application provides a gas injection device for a foam injection molding machine. The following technical solutions are adopted:

[0007] A gas injection device for a foaming injection molding machine, a gas source, is used to store inert gas.

[0008] The cam is provided with a check valve for intake and output of the gas source, and the check valve is provided ...

[0009] By adopting the above technical solution, the gas injection device uses a connecting rod mechanism to transmit the movement of the injection screw to the gas injection piston, so that the injection screw can synchronously compress the volume of the gas storage chamber of the gas injection cylinder when pushing the melt to plasticize, allowing the inert gas to automatically enter the injection barrel through the gas injection head by pressure balance, simplifying the existing gas injection system and reducing costs. The gas injection process is coordinated with the plasticizing process, which is beneficial to the flow rate and injection stroke of the inert gas, automatically matching the flow rate and plasticizing stroke of the melt, and uniformly mixing with the melt, without the need for a complex control system and precise and expensive gas flow measurement and adjustment.

[0010] Optionally, the connecting rod 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 on the sliding sleeve, and the end of the second connecting rod is provided with a limited position arranged on the limit end of the sliding sleeve.

[0011] By adopting the above technical solution, the structural composition of the connecting rod mechanism is disclosed. The connecting rod 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 the mechanism when the injection screw is pre-plasticized and retreats, compressing the volume of the gas storage chamber and allowing the inert gas to enter the injection barrel through the gas injection head; the end of the second connecting rod is provided with a limiting end arranged on the sliding sleeve, which can ensure the stability and accuracy of the gas injection piston moving with the injection screw, thereby achieving stable gas injection.

[0012] Optionally, a plurality of hinged parts are arranged at intervals on the first connecting rod, and a hinged rod rotatably matched with the hinged part and a horizontal driving member driving the hinged rod to move horizontally are provided on one side of the injection barrel for lifting.

[0013] By adopting the above technical solution, the first connecting rod is provided with multiple hinged parts, which cooperate with the lifting hinged rod and the horizontal driving part. Through the cooperation between the hinged rod and different hinged seats, the connecting rod length ratio, L2 / L1, is changed, thereby adjusting the gas injection amount during pre-molding to adapt to the gas injection requirements of different products.

[0014] Optionally, the stroke of the air injection cylinder is S2, the stroke of the injection screw is S1, the length of the first connecting rod from the hinged rod to the injection screw is L1, and the length of the first connecting rod from the hinged rod to the limit end is L2.

[0015] .

[0016] By adopting the above technical solution, a certain relationship is satisfied between the injection cylinder stroke S2, the injection screw stroke S1 and the lengths of different parts of the first connecting rod, and the sliding amount of the injection piston in the injection cylinder can be accurately controlled, thereby accurately controlling the amount of inert gas injected into the injection barrel by the injection cylinder, so that the mass ratio of the inert gas and the melt is constant, and the structure of the injection device is simple and reliable.

[0017] Optionally, the diameter of the gas injection cylinder is d, the volume of the gas injection cylinder is V, and the gas injection volume of the gas injection cylinder is determined by the stroke S2 ​​and the diameter d of the gas injection cylinder.

[0018] .

[0019] By adopting the above technical solution, the gas injection volume of the gas injection cylinder is determined by the gas injection cylinder stroke S2 ​​and diameter d. The gas injection volume can be flexibly controlled to adapt to different production needs. By replacing gas injection cylinders with different outer diameters, the gas injection volume can be adjusted.

[0020] Optionally, a hinged portion is provided on the first connecting rod so as to slide along the length direction, and a hinged rod is provided on one side of the injection barrel so as to be lifted and lowered and rotatably matched with the hinged portion.

[0021] By adopting the above technical solution, the hinge part is set to slide along the length direction of the first connecting rod, so that the hinge rod drives the hinge part to move up and down directly, realizing stepless adjustment of the ratio of L2 and L1, and further adapting to the gas injection requirements of different products.

[0022] Optionally, the gas injection device includes a plurality of gas injection cylinders arranged in parallel, each of which has a gas injection piston slidably installed therein, adjacent gas injection cylinders are arranged in parallel, and a plurality of groups of gas injection pistons are fixed to the second connecting rod.

[0023] By adopting the above technical solution, another way to adjust the gas injection volume is provided. Multiple parallel and parallel gas injection cylinders work together, and cooperate with multiple groups of gas injection pistons fixed to the second connecting rod to increase the gas storage capacity and gas injection flow of the gas injection device.

[0024] 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 sealing head sealing the end of the gas injection head valve body;

[0025] The gas injection shaft and the inner wall of the gas injection head valve body are formed with a gas transmission narrow slit, the gas injection sealing head is provided with a sealing inclined surface, and the gas injection head valve body is provided with a gas injection head pressure action chamber that is in contact with the sealing inclined surface. When the pressure of the gas storage chamber is higher than the melt pressure by 0.5-2 MPa, the gas injection one-way valve is in an open state, and the gas is transported from the gas storage chamber to the injection barrel.

[0026] By adopting the above technical solution, the structural composition of the gas injection head is disclosed. When the pressure of the gas storage chamber is higher than the melt pressure by 0.5-2 MPa, the gas injection one-way valve opens, and the 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 action chamber, 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, thereby ensuring the stability and accuracy of the gas injection process and avoiding the melt in the injection barrel from flowing into the gas injection head valve body.

[0027] Optionally, it also includes a pressure maintaining component for maintaining the pressure of the gas injection cylinder, and the pressure maintaining component includes a boosting one-way valve, a directional valve and a boosting cylinder. The two ends of the boosting one-way valve are respectively connected to the gas storage chamber and the directional valve. The directional valve controls the piston rod of the boosting cylinder, and the gas in the boosting cylinder enters the gas storage chamber in one direction through the boosting one-way valve.

[0028] By adopting the above technical solution and setting the pressure-maintaining component, the injection cylinder can maintain stability and high pressure, making the injection process more reliable and helping to improve the quality of products produced by the foam injection molding machine.

[0029] Optionally, a safety exhaust assembly is also included, which includes a manual exhaust valve, a safety valve and a pressure gauge. The gas discharge from the gas storage chamber is controlled by the manual exhaust valve. The pressure gauge is used to monitor the gas discharge pressure. A muffler is also provided at the output end of the safety valve.

[0030] By adopting the above technical solution, the manual exhaust valve can control the gas discharge from 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 muffler can be used to reduce the noise caused by the sudden discharge of high-pressure gas exceeding the set safety pressure, thereby reducing the impact on the surrounding environment and personnel.

[0031] In summary, this application includes at least one of the following beneficial technical effects:

[0032] This application connects the gas injection piston and injection screw via a connecting rod mechanism. When the injection screw is injecting, it drives the gas injection piston to draw in gas from the gas source. When the injection screw is pre-molding, it drives the gas injection piston to compress the gas storage chamber to allow inert gas to enter the injection barrel. This simplifies the structure of the gas injection device and the complex software control, while also simplifying the process and reducing manufacturing costs.

[0033] The application can ensure the required high pressure and pressure stability of the gas injection cylinder by setting the pressure maintaining component, ensure the stability of the gas injection volume, and improve the foaming quality of the product;

[0034] This application uses the air intake pressure of the injection head, the spring force and the pressure of the injection melt to always have the pressure to close the injection head, thereby ensuring the sealing of the injection head piston, the sensitivity of the injection head opening, and reducing the reflux of the melt. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is a schematic diagram of the overall structure of an embodiment of the present application.

[0036] Figure 2 It is a structural schematic diagram of the connecting rod mechanism of an embodiment of the present application.

[0037] Figure 3 It is a structural schematic diagram of the fixing bracket of an embodiment of the present application.

[0038] Figure 4 It is a structural schematic diagram of the hinged portion and the hinged rod of an embodiment of the present application under stepless adjustment.

[0039] Figure 5 It is a structural schematic diagram of the gas injection head in the closed state according to an embodiment of the present application.

[0040] Figure 6 It is a structural schematic diagram of the gas injection head in an open state according to an embodiment of the present application.

[0041] Figure 7 yes Figure 5 Schematic diagram of the cross section at AA in the middle.

[0042] Figure 8 It is a schematic diagram of the gas path principle of the pressure maintaining component and the safety exhaust component of the embodiment of the present application.

[0043] Explanation of reference numerals: 1. gas source; 2. inlet check valve; 3. gas injection cylinder; 31. gas storage chamber; 4. gas injection piston; 5. connecting rod mechanism; 51. first connecting rod; 511. hinged portion; 512. strip-shaped through hole; 52. sliding sleeve; 53. second connecting rod; 531. position limiting end; 54. position limiting ring; 6. gas injection head; 61. gas injection head valve body; 611. gas inlet; 612. gas outlet; 6121. gas injection head pressure chamber; 613. first gas injection chamber; 614. second gas injection chamber; 615. annular receiving groove; 62. gas injection head piston; 621. gas injection through hole; 6 3. Spring; 64. Gas injection shaft; 641. Gas delivery slit; 65. Gas injection sealing head; 651. Sealing inclined surface; 7. Gas injection check valve; 8. Pressure maintaining assembly; 81. Boost check valve; 82. Directional valve; 83. Boost cylinder; 84. Suction check valve; 9. Safety exhaust assembly; 91. Manual exhaust valve; 92. Safety valve; 93. Pressure gauge; 94. Muffler; 10. Pressure reducing valve; 11. Injection screw; 12. Injection barrel; 13. Fixed bracket; 131. Lifting platform; 132. Make way slot; 133. Positioning socket; 14. Articulated rod; 15. Horizontal drive member. DETAILED DESCRIPTION

[0044] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation. Since the embodiments disclosed in the present invention can be set in different directions, these terms indicating directions are only for illustration and should not be regarded as limitations. For example, "up" and "down" are not necessarily limited to directions opposite to or consistent with the direction of gravity. In addition, features defined as "first" and "second" may explicitly or implicitly include one or more of such features.

[0045] The following is combined with Figure 1-8 This application is described in further detail.

[0046] The embodiment of the present application discloses a gas injection device for a foam injection molding machine.

[0047] Reference Figure 1 The gas injection device of the foam injection molding machine includes a gas source 1, an air inlet one-way valve 2, a gas injection cylinder 3, a gas injection piston 4, a connecting rod mechanism 5, a gas injection head 6, a gas injection one-way valve 7, a pressure maintaining component 8 and a safety exhaust component 9.

[0048] The gas source 1 is an inert gas cylinder commonly used in the prior art, which stores inert gas. 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 of the gas.

[0049] The air intake check valve 2 is arranged between the air source 1 and the air injection cylinder 3 , and the inert gas from the air source 1 enters the air injection cylinder 3 in a one-way manner through the air intake check valve 2 .

[0050] The gas injection piston 4 is slidably mounted on the gas injection cylinder 3, so that the end of the gas injection piston 4 and the inner cavity of the gas injection cylinder 3 form a gas storage chamber 31 for storing inert gas. The gas injection cylinder 3 has two communication holes connected to the gas storage chamber 31. One of the communication holes is connected to the gas inlet check valve 2 and is used for inputting inert gas, serving as an input hole. The other communication hole is connected to the gas injection head 6 and is used for outputting inert gas, serving as an output hole.

[0051] The gas injection check valve 7 is provided between the gas injection head 6 and the gas injection cylinder 3, through which the inert gas in the gas injection cylinder 3 can only enter the gas injection head 6. The output end of the gas injection head 6 is connected to the injection barrel 12 of the injection molding machine.

[0052] Reference Figure 2 and Figure 3 The connecting rod mechanism 5 is used to connect the gas injection piston 4 and the injection screw 11 in the injection barrel 12, so that the injection screw 11 and the gas injection piston 4 form a linkage. When the hydraulic system controls the injection screw 11 to pre-plasticize and retreat, the gas injection piston 4 is driven by the connecting rod mechanism 5 to slide forward in the gas injection cylinder 3, 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 gas injection one-way valve 7 and the gas injection head 6, realizing automatic injection of gas into the melt and mixing with it.

[0053] The connecting rod mechanism 5 includes a first connecting rod 51, a sliding sleeve 52, and a second connecting rod 53. A limiting ring 54 is mounted on one end of the first connecting rod 51 to limit its position on the injection screw 11. The limiting ring 54 is hingedly connected to the first connecting rod 51. The limiting ring 54 and the injection screw 11 slide together, ensuring that rotation of the injection screw 11 does not cause synchronous rotation of the first connecting rod 51.

[0054] The sliding sleeve 52 is a vertically arranged cylindrical sleeve. The other end of the first connecting rod 51 is fixedly connected to the bottom of the sliding sleeve 52. The sliding sleeve 52 defines a sliding chamber along its length. One end of the second connecting rod 53 is provided with a stopper 531 disposed in the sliding chamber. The other end of the second connecting rod 53 is fixedly connected to the end of the gas injection piston 4.

[0055] In order to adjust the amount of gas injected in 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 in shape 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 achieve 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, etc. 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 opposite to the hinged rod 14 , so as to improve the stability of the hinged rod 14 .

[0056] Define the stroke of the 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 injection cylinder 3 to the pre-molding stroke S1 of the screw is determined by the L2 / L1 of the first connecting rod 51, as shown in the following formula:

[0057] .

[0058] 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 air pressure, the gas injection volume of the gas injection cylinder 3 is determined by the stroke S2 ​​of the gas injection cylinder 3 and the diameter d. The specific formula is as follows:

[0059] .

[0060] In other embodiments, a hinge portion 511 is slidably installed on the first connecting rod 51 along its length direction. The first connecting rod 51 is provided with a strip-shaped through hole 512 for limiting the sliding arrangement of the hinge portion 511. The hinge portion 511 and the hinge rod 14 are rotatably matched.

[0061] 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.

[0062] In other embodiments, the gas injection device includes multiple gas injection cylinders 3, which are arranged in parallel with each other. The gas injection pistons 4 of the multiple gas injection cylinders 3 are fixed to 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 multiple gas injection pistons 4 to slide synchronously, realizing multi-cylinder synchronous gas injection operation.

[0063] 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 fixedly connected. The top of the gas injection head valve body 61 has an air inlet 611 connected to the gas injection cylinder 3, and the bottom has an air outlet 612 connected to the injection barrel 12. Among them, the gas injection head valve body 61 is provided with a gas injection head pressure action chamber 6121 at the air outlet 612, and the gas injection head pressure action chamber 6121 is generally in the shape of a trumpet with an opening downward. The side wall of the gas injection sealing head 65 is provided with a sealing inclined surface 651 that fits with the gas injection head pressure action chamber 6121.

[0064] The gas injection head valve body 61 is also provided with an annular accommodating groove 615 between the gas injection head pressure action chamber 6121 and the second gas injection chamber 614. The annular accommodating groove 615 is connected to the gas transmission narrow slit 641 so that gas can be pre-stored in the annular accommodating groove 615, which facilitates the efficient and stable pushing of the gas injection sealing head 65 during gas injection.

[0065] A first gas injection chamber 613, in which the gas injection piston 62 slides, and a second gas injection chamber 614, in which the gas injection shaft 64 slides, are located along one side of the gas injection head valve body 61. The outer diameter of the gas injection head piston 62 is generally larger than that of the gas injection shaft 64, thereby limiting the opening of the gas injection head 6. A spring 63 is sleeved around the gas injection head piston 62, with its ends abutting the bottom walls of the gas injection head piston 62 and the first gas injection chamber 613, respectively.

[0066] The gas injection head piston 62 is provided with spaced apart gas injection holes 621 for gas flow, and the gas injection holes 621 are arranged alternately with the gas inlet 611. The radial cross-section of the gas injection shaft 64 is an incomplete circular surface, so that the sidewalls of the gas injection shaft 64 and the inner wall of the second gas injection cavity 614 are formed with gas transmission slits 641 for gas flow.

[0067] Before gas injection, the gas injection sealing head 65 and the gas outlet 612 are sealed. Simultaneously, the top of the gas injection head piston 62 abuts against 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 sealed. When the pressure in the gas storage chamber 31, driven by the gas injection head piston 62, exceeds the melt pressure by 0.5-2 MPa, the gas injection check valve 7 opens at this pressure and pushes the gas injection head piston 62 downward, allowing gas to enter the injection barrel 12 along the first gas injection chamber 613, the gas delivery slit 641, and the gas outlet 612.

[0068] Reference Figure 6The pressure-maintaining assembly 8 is used to ensure the injection pressure in the gas injection cylinder 3, and includes a boosting check valve 81, a directional valve 82, a boosting cylinder 83, and an intake check valve 84. The two 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 direction of gas flow 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 intake check valve 84, and the air path between the intake directional valve 82 and the input hole of the gas injection cylinder 3 and the input end of the intake check valve 84 are connected to facilitate the intake of gas by the boosting cylinder 83.

[0069] The normal injection pressure of injection cylinder 3 is set and monitored by a pressure relay (not shown). When the gas pressure in injection cylinder 3 falls below the set value, directional valve 82 opens, and booster cylinder 83 pumps gas through directional valve 82 and boost check valve 81 into gas storage chamber 31 until the pressure reaches the set injection pressure.

[0070] The safety exhaust assembly 9 is used to discharge the gas in the gas injection cylinder 3 so that when the injection molding machine stops working, the pressure in the gas injection cylinder 3 is kept in balance with the outside atmosphere, thereby improving the service life of the gas 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, wherein the safety valve 92 is used to ensure that the pressure in the gas injection cylinder 3 does not exceed the safety level, and the pressure gauge 93 is used to monitor the pressure before exhaust, thereby further improving the safety of exhaust.

[0071] The implementation principle of the gas injection device of a foam injection molding machine in the embodiment of the present application is as follows: when the injection screw 11 is pre-molding, the injection screw 11 retreats horizontally, and under the action of the connecting rod mechanism 5, drives the gas injection piston 4 forward and compresses the air pressure of the gas storage chamber 31. When the air pressure in the gas storage chamber 31 exceeds the gas injection check valve 7, gas injection begins, and the gas overcomes the melt pressure at the gas injection head 6, causing the gas injection head piston 62, the gas injection shaft 64 and the gas injection sealing head 65 to slide downward, so that the gas can enter the injection barrel 12 and mix with the melt until the injection screw 11 stops pre-molding displacement, or the gas pressure in the gas injection cylinder 3 is lower than the melt pressure of the gas injection head 6, and the gas injection also stops synchronously;

[0072] When the injection screw 11 starts to move forward for injection, the piston of the gas injection cylinder 3 moves backward, and gas is sucked from the gas source 1 through the gas inlet check valve 2 to replenish the gas injection cylinder 3. At this time, the directional valve 82 is in the closed state. If the gas pressure in the gas injection cylinder 3 is lower than the pressure set by the pressure relay, the directional valve 82 switches to the open position, and the booster cylinder 83 opens to input gas into the gas storage chamber 31. The pressure maintaining assembly 8 ensures that the gas injection pressure in the gas injection cylinder 3 reaches the set pressure.

[0073] When the injection molding machine stops working, the staff manually controls the manual exhaust valve 91 to release air, thereby reducing the time that the injection cylinder 3 is under high pressure for a long time and improving its service life.

[0074] The above are all preferred embodiments of the present application, and are not intended to limit the scope of protection of the present application. Therefore, any equivalent changes made based on the structure, shape, and principle of the present application should be included in the scope of protection of the present application.

Claims

1. A gas injection device for a foaming injection molding machine, characterized in that: include: A gas source (1) for storing inert gas; A pressure reducing valve (10) for adjusting the outlet pressure of the gas source (1); An air inlet check valve (2) connected to the output end of the air source (1); The gas injection cylinder (3) is located between the gas source (1) and the gas inlet one-way valve (2), and has a gas storage chamber (31) for storing gas. The inert gas from the gas source (1) enters the gas injection cylinder (3) in a one-way manner through the pressure reducing valve (10) and the gas inlet one-way valve (2); A gas injection piston (4) slidably mounted on the gas injection cylinder (3); A connecting rod mechanism (5) for connecting the gas injection piston (4) and the injection screw (11); A gas injection head (6) communicating with the gas storage chamber (31) and the injection barrel (12); A gas injection one-way valve (7) is located between the gas injection head (6) and the gas injection cylinder (3), and the gas in the gas storage chamber (31) enters the injection barrel (12) in a one-way manner through the gas injection one-way valve (7); When the injection screw (11) pre-molds and retreats, the gas injection piston (4) is driven to slide in the gas injection cylinder (3) through the connecting rod mechanism (5), compressing the volume of the gas storage chamber (31), so that the inert gas pressure overcomes the melt pressure of the gas injection head (6), thereby opening the gas injection head (6) and entering the injection barrel (12) through the gas injection head (6); The connecting rod mechanism (5) includes a first connecting rod (51), a sliding sleeve (52) and a second connecting rod (53), wherein both ends of the first connecting rod (51) are fixed to the injection screw (11) and the sliding sleeve (52), respectively; one end of the second connecting rod (53) is fixed to the gas injection piston (4), and the other end is slidingly mounted on the sliding sleeve (52); and the end of the second connecting rod (53) is provided with a limiting end (531) arranged on the sliding sleeve (52); A plurality of hinged portions (511) are arranged at intervals on the first connecting rod (51), and a hinged rod (14) that rotates with the hinged portion (511) and a horizontal driving member (15) that drives the hinged rod (14) to move horizontally are arranged on one side of the injection barrel (12) for lifting and lowering, or a hinged portion (511) is arranged on the first connecting rod (51) for sliding along the length direction, and a hinged rod (14) that rotates with the hinged portion (511) is arranged on one side of the injection barrel (12) for lifting and lowering.

2. The gas injection device of a foaming injection molding machine according to claim 1, characterized in that: The stroke of the air injection cylinder (3) is S2, the stroke of the injection screw (11) is S1, the length of the first connecting rod (51) from the hinged rod (14) to the injection screw (11) is L1, and the length of the first connecting rod (51) from the hinged rod (14) to the limiting end (531) is L2. 。 3. The gas injection device of a foaming injection molding machine according to claim 2, characterized in that: The diameter of the gas injection cylinder (3) is d, the volume of the gas injection cylinder (3) is V, and the gas injection amount of the gas injection cylinder (3) is determined by the stroke S2 ​​and the diameter d of the gas injection cylinder (3). 。 4. The gas injection device of a foaming injection molding machine according to claim 1, characterized in that: The gas injection device comprises a plurality of gas injection cylinders (3) arranged in parallel, wherein a gas injection piston (4) is slidably installed in each of the gas injection cylinders (3), and adjacent gas injection cylinders (3) are arranged in parallel, and a plurality of groups of gas injection pistons (4) are fixed to a second connecting rod (53).

5. The gas injection device of a foaming injection molding machine according to claim 1, characterized in that: The gas injection head (6) comprises 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 sealing head (65) sealing the end of the gas injection head valve body (61); The gas injection shaft (64) and the inner wall of the gas injection head valve body (61) are formed with a gas transmission narrow slit (641) for gas to pass through, the gas injection sealing 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 action chamber (6121) in contact with the sealing inclined surface (651). When the pressure of the gas storage chamber (31) is higher than the melt pressure by 0.5-2 MPa, 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).

6. The gas injection device of a foaming injection molding machine according to claim 1, characterized in that: It also includes a pressure-maintaining assembly (8) for maintaining the injection pressure of the injection cylinder (3), the pressure-maintaining assembly (8) including a boosting check valve (81), a directional valve (82), a boosting cylinder (83), and an air intake check valve (84), the two ends of the boosting check valve (81) being connected to the air storage chamber (31) and the directional valve (82), respectively, and the directional valve (82) controlling the boosting action of the boosting cylinder (83); During pressurization, the directional valve (82) is opened, and the pressurized gas enters the gas storage chamber (31) through the directional valve (82) and the pressurization check valve (81); After the pressure is increased, the directional valve (82) is closed, and the booster cylinder (83) is reset by sucking gas from the gas source (1) through the suction check valve (84).

7. The gas injection device of a foaming injection molding machine according to claim 1, characterized in that: The invention also includes a safety exhaust assembly (9), which includes a manual exhaust valve (91), a safety valve (92) and a pressure gauge (93). The manual exhaust valve (91) is used to control the gas discharge from the gas storage chamber (31). The pressure gauge (93) is used to monitor the pressure of the gas before discharge. A muffler (94) is also provided at the output end of the safety valve (92).

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