A pneumatic synchronous mixing and injecting gun for a two-component low-temperature foaming plugging material for mines and a construction method thereof

Abstract

This application relates to the field of underground coal mine construction equipment technology, specifically to a pneumatic synchronous mixing gun and construction method for a two-component low-temperature foaming sealing material for mining. The mixing gun includes a gun frame, two rubber sleeve fixing seats, a pneumatically balanced synchronous pushing mechanism, and a confluence mixing assembly. The pneumatically balanced synchronous pushing mechanism uses equal-diameter cylinders in conjunction with rigid synchronous connecting rods to achieve a 1:1 constant-volume pushing of the two components, with the pushing volume determined by geometric displacement. The confluence mixing assembly includes a Y-shaped three-way outlet connected in series and a static mixer. The static mixer has mixing elements arranged along the material flow direction to guide the material flow and ensure thorough mixing before discharge. Based on the above mixing gun, this invention also provides a corresponding construction method, effectively solving the problems of difficulty in maintaining a 1:1 ratio of the two-component material under high viscosity differences and uneven material mixing and foaming during construction. It is suitable for coal mine fire prevention and extinguishing and gas sealing operations.

Description

Technical Field

[0001] This invention relates to the field of underground coal mine construction equipment technology, specifically to a pneumatic synchronous mixing gun and construction method for a two-component low-temperature foaming sealing material for mining. Background Technology

[0002] In coal mines, gas can easily accumulate in goaf areas, upper and lower corners, high-risk areas in roadways, and fractured zones, which can induce spontaneous combustion of coal. These areas need to be filled and sealed to isolate oxygen and cool the soil. At the same time, sealing holes are needed between the borehole wall and casing of extraction boreholes and in the air leakage channels of goaf areas to prevent gas leakage and air leakage. Currently, two-component low-temperature foamed sealing materials for mining have been widely used in coal mine safety production. They are usually made by mixing two materials in a 1:1 volume ratio: Component A (an inorganic silicate phosphate solution or gel, a milky white viscous liquid with a density of 1.25 g / cm³ and a viscosity of ≤270 mPa·s) and Component B (an acidic coagulant or polyisocyanate, a colorless or pale yellow transparent liquid with a density of 1.08 g / cm³ and a viscosity of ≤10 mPa·s, nearly watery). The reaction temperature after mixing is basically the same as the environment. The materials are selected with consideration for characteristics such as rapid initial setting (1-5 min), final setting of 30-60 min, closed-cell rate of the solidified body ≥85%, oxygen index ≥40%, and non-combustibility at 1000℃.

[0003] In existing technologies, the construction equipment for two-component low-temperature foamed sealing materials mainly adopts a structure driven by two independent pneumatic pumps. This involves using two independent pneumatic pumps to push material A and material B to the nozzle for direct mixing and discharge. While this approach is relatively simple, the difference in viscosity between materials A and B makes it difficult to maintain a precise 1:1 volume ratio between the pneumatic pumps due to inconsistent pressure loss characteristics. This is especially problematic under low-flow conditions or with large viscosity differences (such as the aforementioned materials with a viscosity difference of up to 27 times), where the synchronization and mixing accuracy of the two pneumatic pumps become even more difficult to guarantee. Furthermore, this method involves directly discharging the material before foaming. When the viscosity difference between materials A and B is significant, the lower-viscosity material tends to flow rapidly along the pipe wall (wall-adhering short-circuiting phenomenon), while the higher-viscosity material tends to flow towards the center of the pipe. This results in insufficient contact between the two materials, incomplete local reactions, and an inability to strictly guarantee a 1:1 mixing ratio between materials A and B, ultimately leading to uneven foaming ratio and strength.

[0004] Other methods, such as electric grouting pumps, are used to improve the synchronous accuracy of two-component material construction. However, these devices are usually large and difficult to move in narrow underground spaces. Furthermore, due to their electric drive, they pose potential explosion-proof safety risks in mining areas and cannot meet the stringent requirements for safe production in mines.

[0005] In summary, existing technologies for constructing two-component low-temperature foamed plugging materials for mining suffer from several common problems, including insufficient 1:1 mixing accuracy, difficulty in achieving stable material output, incomplete mixing and foaming reaction, and bulky overall equipment structure. These issues hinder the improvement of construction quality and efficiency in mining plugging operations. Therefore, there is an urgent need in this field for a portable device that can maintain a strict 1:1 volume ratio and uniform mixing of two-component materials with high viscosity differences under explosion-proof conditions underground, along with corresponding improvements to the construction methods. Summary of the Invention

[0006] This invention provides a pneumatic synchronous mixing gun and construction method for a two-component low-temperature foaming sealing material for mining, to solve the problems in the prior art. The mixing gun includes: Gun frame, serving as the supporting skeleton for the mixing gun; Two rubber tube fixing seats are symmetrically installed on both sides of the gun body frame to fix the rubber tube containing the material. The front end of the rubber tube fixing seat is provided with a discharge port. A pneumatic balancing synchronous pushing mechanism, mounted on the gun frame, includes a pneumatic balancing chamber, a left-side cylinder and a right-side cylinder connected to the pneumatic balancing chamber and arranged in parallel on the left and right sides of the gun frame, a left-side piston rod installed in the left-side cylinder, a right-side piston rod installed in the right-side cylinder, and a synchronous connecting rod rigidly connecting the left-side piston rod and the right-side piston rod; the pneumatic balancing chamber is provided with an air source inlet connected to an external air source; the left-side cylinder and the right-side cylinder have the same structure and cylinder diameter; the left-side piston rod and the right-side piston rod are used to push the material in the rubber cylinder out of the discharge port. The confluence mixing assembly includes a Y-shaped tee connected to the discharge port and a static mixer connected in series with the outlet of the Y-shaped tee. The static mixer is hollow inside and is provided with several mixing elements to guide the flow of materials for thorough mixing. The front end of the static mixer is provided with a glue gun nozzle.

[0007] Furthermore, the rubber tube fixing seat includes a hollow seat, an elastic clamp disposed inside the seat, and a push plate movably disposed inside the seat and moving along the axial direction of the seat. The elastic clamp is used to clamp the rubber tube inside the seat, and the push plate is connected to the front end of the left piston rod or the right piston rod and can be axially pushed between the elastic clamps.

[0008] Furthermore, the left and right cylinders are connected to the pneumatic balance chamber via air pipes, and the air pipes are equipped with openable and closable air valves.

[0009] Furthermore, the static mixer adopts a segmented design, and the mixing elements along the material flow direction include, in sequence: an upstream large-pitch spiral element, a midstream small-pitch staggered spiral element, and a downstream orifice plate turbulence generator; the large-pitch spiral element is a number of unidirectional spiral guide structures set on the inner wall of the upstream of the static mixer, the small-pitch staggered spiral element is a number of bidirectional spiral guide structures set on the inner wall of the static mixer, and the orifice plate turbulence generator is a number of baffles with openings vertically set in the inner cavity of the static mixer, with the openings of adjacent baffles arranged in an alternating manner.

[0010] Furthermore, the aspect ratio of the static mixer is greater than or equal to 12, and the cavity length occupied by the large-pitch helical element, the small-pitch staggered helical element, and the orifice plate turbulence generator arranged along the axial direction of the static mixer cavity is equal.

[0011] Furthermore, the Y-type tee is connected to the discharge port via a one-way check valve. The one-way check valve includes a hollow valve body, a piston rod valve core, and a return spring. One end of the hollow valve body is connected to the discharge port, and the other end is connected to the inlet of the Y-type tee. One end of the return spring is fixed inside the hollow valve body, and the other end is fixedly connected to the piston rod valve core. The return spring provides a preload force to push the piston rod valve core towards the discharge port, so that the piston rod valve core covers the discharge port.

[0012] Furthermore, the piston rod valve core is made of polytetrafluoroethylene, which has self-lubricating properties.

[0013] Furthermore, the static mixer and the Y-tee are connected by a quick-release mechanism.

[0014] Furthermore, the front end of the static mixer is provided with an airflow regulating channel, which is connected to an external compressed air source and is equipped with a regulating valve. The regulating valve is a needle valve structure, and the flow rate of compressed air entering the static mixer is controlled by regulating the opening degree of the regulating valve.

[0015] Based on the above technical solution, the present invention provides a pneumatic synchronous mixing and injection method for a two-component low-temperature foamed sealing material for mining, comprising the following steps: Step 1: According to the requirements of the construction sealing materials, select rubber tubes filled with material A and material B respectively and insert them into the rubber tube fixing base; Step 2: Connect the pneumatic balancing chamber to an external air source and check the status of each device. Step 3: Aim the mixing gun at the area to be sealed, start the external air source, and the air source enters the pneumatic balance chamber, acting simultaneously on the left and right cylinders. Step four: Under the mechanical locking action of the rigid synchronous connecting rod, the left and right piston rods are driven by the air source synchronously discharged from the pneumatic balance chamber to move synchronously and act on the rubber cylinder to push out material A and material B in equal amounts simultaneously. Step 5: Material A and Material B are pre-mixed in a static mixer via a Y-shaped tee. At the same time, the regulating valve is adjusted to control the amount of air in contact with Material A and Material B according to the set foaming ratio, and the foamed material is discharged to seal the construction area.

[0016] Compared with the prior art, the present invention has the following beneficial effects: 1. For the construction of two-component low-temperature foaming sealing materials, the mixing gun of this invention is equipped with a pneumatic balance synchronous pushing mechanism that works in conjunction with a cartridge containing two materials. The left and right cylinders are arranged in parallel on the left and right sides of the pneumatic balance chamber, and the cylinder diameters of the left and right cylinders are consistent. When the air pressure provided by the external air source acts on the left and right cylinders simultaneously, since the cylinder diameters of the two cylinders are consistent, the displacement distance and movement speed of the left and right piston rods are always consistent during the air source drive process, achieving the effect of synchronous displacement. This allows the A and B materials in the left and right cartridges to be pushed out synchronously with equal pushing volume. The pushing volume is determined by geometric displacement and is not affected by the viscosity difference of the components. This effectively solves the problem of mixing accuracy deviation caused by the use of independent pneumatic pumps in the prior art. Especially under low flow conditions or when there is a large viscosity difference between A and B materials, it can also ensure a 1:1 synchronous output of the two.

[0017] 2. The pneumatically balanced synchronous pushing mechanism ensures a 1:1 pushing output between materials A and B from the source. Furthermore, this invention, through the inclusion of a confluence mixing component, provides space within the static mixer's inner cavity for pre-mixing and reaction of the materials. Materials A and B from the two cartridges converge at the Y-shaped tee and enter the static mixer. The internal mixing elements eliminate wall-adhering short-circuiting and laminar separation caused by viscosity differences between the materials, allowing for thorough pre-mixing and further enhancing the uniformity of the mixture. This improves the uniformity and consistency of the foamed sealing material. This also supplements the 1:1 ratio reaction between materials A and B, effectively preventing situations where one material participates more in the mixing reaction than the other due to wall-adhering short-circuiting or laminar separation. Moreover, the pre-mixing reaction ensures immediate foaming upon material discharge, effectively guaranteeing the quality requirements of the sealing construction.

[0018] 3. This invention replaces the existing electric drive with a pneumatic drive. The entire mixing gun does not contain electric components and does not require an external power supply. It can achieve the 1:1 delivery requirement of sealing materials, fully meeting the explosion-proof requirements for safe production in mines. At the same time, the pneumatic drive makes the equipment more compact and lightweight, making it easy to move and operate in narrow underground spaces. It can be put into use on-site in the mine by simply connecting to an external air source, greatly improving construction efficiency.

[0019] 4. This invention also effectively prevents residual material in the cartridge from continuing to flow out due to its own pressure after material feeding stops, thus affecting the material ratio of the mixing reaction; it also prevents material from flowing back and clogging the pipeline. Furthermore, by adding an airflow regulating channel with a regulating valve at the front end of the static mixer, on-site operators can precisely adjust the amount of compressed air entering the static mixer according to the required foaming ratio, thereby controlling the foaming ratio and achieving flexible adjustment of the foaming volume under different construction scenarios, further expanding the applicability of this device. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the overall structure of the mixing gun of the present invention; Figure 2 This is a flowchart illustrating the working principle of the mixing gun of the present invention; Figure 3 This is a static cross-sectional view of the mixer of the mixing gun of the present invention; Figure 4 This is a cross-sectional view of the one-way check valve of the mixing gun of the present invention; Figure 5 This is a cross-sectional schematic diagram of the glue cartridge fixing seat of the mixing gun of the present invention; In the attached diagram: 1. Gun frame; 2. Glue cartridge holder; 21. Discharge port; 22. Seat cylinder; 23. Elastic clamp; 24. Push plate; 3. Pneumatic balance chamber; 31. Air source inlet; 32. Air pipe; 33. Air valve; 4. Left cylinder; 41. Left piston rod; 5. Right cylinder; 51. Right piston rod; 6. Synchronous connecting rod; 7. Combination mixing assembly; 71. Y-type tee; 72. Static mixer; 73. Glue nozzle; 74. Large pitch spiral element; 75. Small pitch staggered spiral element; 76. Orifice plate turbulence generator; 8. One-way check valve; 81. Hollow valve body; 82. Piston rod valve core; 83. Return spring; 9. Airflow regulating channel; 91. Regulating valve. Detailed Implementation

[0021] The technical solution of the present invention will now be described with reference to the accompanying drawings. However, the described embodiments are only some embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0022] It should be noted that in the description of this invention, the terms "left", "right", "front", "rear", etc., which indicate the direction or positional relationship, are based on the direction or positional relationship shown in the accompanying drawings. For example, "front" refers to the output direction of the sealing material. This is only for the convenience of description and does not indicate or imply that the device or element must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation of this invention.

[0023] In the description of this invention, unless otherwise explicitly specified and limited, the terms "set", "install", "connect", and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to an electrical connection or a mechanical connection; they can refer to an indirect connection through an intermediate medium, or they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention in conjunction with the specific circumstances.

[0024] The accompanying drawings show various structural schematic diagrams according to embodiments disclosed in the present invention. These drawings are not drawn to scale, and some details may be enlarged or omitted for illustrative purposes.

[0025] The pneumatic synchronous mixing gun for the mine-use two-component low-temperature foamed sealing material provided by this invention is mainly used in the field of mine sealing construction. The two-component low-temperature foamed sealing material is composed of two materials, A and B. Before describing the specific implementation scheme of this invention, this invention conducted a ratio sensitivity test on the material parameters after the foaming reaction of the mixture of A and B materials. The test results are shown in Table 1 below, which shows that the mixing effect of the two materials A and B materials is best at a ratio of 1:1.

[0026] Table 1. Effect of mixing ratio on material properties (taking a foaming ratio of 10 times as an example)

[0027] In specific implementation plans, such as Figure 1 , 2 As shown, the mixing gun has an overall axisymmetric structure and mainly includes a gun frame 1, two rubber tube fixing seats 2 mounted on the gun frame 1, a pneumatic balance synchronous pushing mechanism mounted on the gun frame 1, and a confluence mixing assembly 7 mounted on the front end of the gun frame 1.

[0028] In the specific structure, the gun frame 1 serves as the supporting skeleton of the entire mixing gun and is made of high-strength steel. Two cartridge fixing seats 2 are symmetrically arranged on the left and right sides of the pneumatic balance synchronous pushing mechanism, respectively, to fix the cartridges filled with sealing materials (i.e., material A and material B). The front end of the cartridge fixing seat 2 is provided with a discharge port 21 for discharging the material from the cartridge.

[0029] The pneumatic balancing synchronous pushing mechanism mainly includes a pneumatic balancing chamber 3, a left cylinder 4, a right cylinder 5, a left piston rod 41, a right piston rod 51, and a synchronous connecting rod 6. The pneumatic balancing chamber 3 is located at the upper central axis of the gun frame 1. Its interior is a hollow structure. An air source inlet 31 is provided on the top or side wall of the pneumatic balancing chamber 3 for connecting to an external compressed air source, such as a compressed air pipeline in an underground working face, to ensure a stable and reliable air source. The pneumatic balance chamber 3 is connected to both the left cylinder 4 and the right cylinder 5. The left cylinder 4 and the right cylinder 5 have the same model, structure, cylinder diameter, and other morphological characteristics, and the size of the ventilation pipe connecting them is also the same. This ventilation pipe is connected and controlled by a trigger structure set on the grip part of the mixing gun frame 1. For example, a ventilation valve can be set on the ventilation pipe. The trigger is mechanically connected to the ventilation valve according to the mechanical lever mechanism transmission principle of firearms. Pulling the trigger opens the ventilation valve, connecting the pneumatic balance chamber to the air passage of the left and right cylinders, and the cylinder pushes the piston rod; releasing the trigger closes the air passage and stops pushing. The opening and closing of the ventilation pipe is achieved by controlling the opening and closing of the ventilation valve. The left cylinder 4 and the right cylinder 5 are respectively arranged on the left and right sides of the gun frame 1, and each has a piston rod installed inside. The left piston rod 41 is installed in the left cylinder 4, and the right piston rod 51 is installed in the right cylinder 5. The compressed air entering from the pneumatic balance chamber 3 can simultaneously act on the piston rods of the two cylinders through the ventilation pipe after the trigger is pulled.

[0030] Furthermore, the left piston rod 41 and the right piston rod 51 are rigidly connected by a synchronizing rod 6. The synchronizing rod 6 is a rigid metal rod that does not bend or deform under the pushing load of the cylinder. Its two ends are fixed to the left piston rod 41 and the right piston rod 51, respectively. The synchronizing rod 6 provides the left piston rod 41 and the right piston rod 51 with additional mechanical synchronization locking capability during the synchronous drive of the cylinder. Even if the viscosity difference causes different pressures on both sides, the mechanical constraint of the synchronizing rod can further maintain the complete synchronous movement of the two piston rods. The movement of any one piston rod will drive the other piston rod to move synchronously through the synchronizing rod 6, thereby further improving the synchronization accuracy of the discharge of materials A and B from the two rubber cylinders.

[0031] Under the above technical solution, when an external air source supplies air to the pneumatic balance chamber 3 through the air source inlet 31, the compressed air is first pre-stored in the pneumatic balance chamber 3. When the trigger of the mixing gun is pulled, opening the air passage between the pneumatic balance chamber 3 and the left and right cylinders, the air pressure is simultaneously transmitted to the left cylinder 4 and the right cylinder 5. Since the two cylinders are completely identical, the air pressure acting on the two piston rods is equal, therefore the thrust on the two piston rods is equal. At the same time, under the rigid connection of the synchronizing rod 6, the left piston rod 41 and the right piston rod 51 move forward at the same speed and displacement, respectively pushing the material in the left and right rubber cylinders installed on the rubber cylinder fixing seat 2 to be discharged synchronously and in equal amounts. When the material pushing stops, it can also be ensured that the two cylinders shut down simultaneously. In the above technical solution, the pneumatic balance chamber provides equal pressure air supply and the synchronous connecting rod provides rigid locking, forming a dual redundant synchronization mechanism: the pneumatic balance chamber ensures equal air supply pressure; the rigid synchronous connecting rod mechanically forces the piston rod displacement to be completely consistent. Even if the viscosity difference between materials A and B is large and the resistance difference is large, if one side is resisted, the connecting rod forces the other side to move synchronously, eliminating the pushing deviation caused by the viscosity difference. This solves the problem of pushing deviation caused by the large viscosity difference between materials and the unequal driving resistance under the independent drive scheme. It can always maintain the 1:1 volume ratio of material A to material B for discharge, meeting the ratio requirements of high viscosity difference two-component foamed sealing material.

[0032] The mixing assembly 7 is located at the front end of the gun frame 1 and is used to receive and pre-mix the materials discharged from the two rubber cylinders. The mixing assembly 7 mainly consists of two parts connected in series: a Y-shaped tee 71 and a static mixer 72. The static mixer 72 has a hollow cavity structure with inlets and outlets. The Y-shaped tee 71 has three ports, two of which are connected to the outlets 21 of the two rubber cylinder fixing seats 2, and the third port is connected to the inlet of the static mixer 72. The static mixer 72 provides a space for pre-mixing and reacting the two sealing materials. It is also equipped with several mixing elements to guide the flow direction of materials A and B after they converge through the Y-shaped tee 71, and to intervene in the flow pattern of the materials. This allows the two materials to be fully mixed and reacted in the static mixer 72 in a 1:1 ratio, avoiding a situation where material A participates in the mixing reaction more than material B (and vice versa). Finally, a uniform foamed colloid is formed and then discharged through the dispensing nozzle 73 to be applied to the construction site to be sealed.

[0033] Specifically, when there is a significant viscosity difference between materials A and B, in order to further reduce the impact of the viscosity difference on material flow and mixing, the internal structure of the static mixer 72 is as follows: Figure 3As shown, it adopts a segmented design. Each mixing element, along the material flow direction, includes, in sequence, an upstream large-pitch spiral element 74, a midstream small-pitch staggered spiral element 75, and a downstream orifice plate turbulence generator 76 (the upstream side is near the Y-shaped tee 71, and the downstream side is near the outlet of the static mixer 72). The large-pitch spiral element 74 consists of several unidirectional spiral guide structures attached and fixed to the inner wall of the static mixer 72. When materials A and B enter the area of ​​the large-pitch spiral element 74, the unidirectional spiral guide structure will divert and guide the materials, causing the two materials to form a rotating flow within the pipe and establish a double-layer distribution in the radial direction, preventing low-viscosity materials from flowing directly along the wall and forming a wall-attached short-circuit phenomenon. The small-pitch staggered spiral element 75 consists of several bidirectional spiral guide structures attached and fixed to the inner wall of the midstream section of the static mixer 72. The direction of these threads alternates between two adjacent pitches, i.e., the first pitch is a left-hand thread, the second pitch is a right-hand thread, and so on, with the thread pitch of the small-pitch staggered spiral element 75 designed to be smaller than that of the large-pitch spiral element 74. When the material passes through the three mixing elements in sequence, its state changes as follows: the upstream large-pitch spiral first breaks the short-circuiting phenomenon of high and low viscosity materials adhering to the wall; the midstream small-pitch staggered spiral continuously cuts, flips, and merges the two streams of material; the downstream orifice plate turbulence generator creates high-intensity turbulence, completely eliminating laminar separation caused by high viscosity differences and achieving thorough mixing. Specifically, when the material passes through the area of ​​the small-pitch staggered spiral element 75, due to the alternating arrangement of the bidirectional threads, the flow of the two materials is continuously divided, overturned, and merged, forming a complex three-dimensional turbulent state within the pipe. Furthermore, the smaller thread pitch increases the number of cuts in the material flow, further cutting and dispersing the material that has already undergone initial separation, reducing the laminar flow thickness, and allowing the two materials to be fully disturbed and mixed, further enhancing the mixing effect. The orifice plate turbulence generator 76 consists of several perforated baffles vertically arranged within the cavity of the static mixer 72. The orifice plate has an opening ratio of 30% to 60% and an aperture of 3 to 6 mm. The baffles are arranged at equal intervals along the material flow direction, with the opening positions of adjacent baffles staggered. When the material passes through area 76 of the orifice plate turbulence generator, the baffle will forcibly change the flow direction of the material. The material must pass through the opening to flow forward. The throttling effect of the opening and the blocking effect of the baffle together generate a strong turbulence effect, forcing the two materials to form a highly turbulent flow state in the mixing chamber, overcoming the laminar separation caused by the high viscosity difference, and further allowing the materials to fully contact and react evenly.

[0034] Furthermore, the static mixer 72 has an aspect ratio (L / D) ≥ 12 and a total number of mixing elements ≥ 12 (for spiral elements, one turn of the thread represents one element). Each of the three mixing elements occupies an equal length of cavity along the axial direction of the static mixer's inner cavity. This parameter setting ensures that the material has sufficient residence time and mixing path within the static mixer 72, and undergoes sufficient processing by the mixing elements, allowing the high-viscosity material A and the low-viscosity material B to fully contact and react chemically. For cases where the viscosity ratio between materials A and B is ≥ 20, after multiple experiments and verifications, the optimal number of mixing elements is 14 to 18, with an L / D ratio of 14 to 18.

[0035] The mixing gun of this invention is designed to simultaneously accommodate rigid rubber cartridges and sausage-shaped soft-pack cartridges (like on-site sausage-style soft packaging). Correspondingly, as... Figure 5 As shown, the rubber tube fixing base 2 includes a hollow base 22, an elastic clip 23 disposed inside the base 22, and a push plate 24 movably disposed inside the base 22. The elastic clip 23 includes at least two clips connected to the inner wall of the base 22 by elastic elements (such as springs). The inner surface of the clips is provided with anti-slip texture, and under the action of the elastic force of the elastic element, it has a tendency to move towards the central axis of the base 22 to adapt to the outer dimensions of the rubber tube and to clamp the rubber tube securely inside the base 22. The pusher plate 24 can move along the internal axis of the seat cylinder 22. The size of the pusher plate 24 is set to match the inner diameter of the smaller size of the rubber tube, so that it can apply a pushing force to the rubber tube to push the filling material in the rubber tube to the discharge port 21 without being affected by the limiting effect of the elastic clamp 23 (that is, the size of the pusher plate 24 is set so that it can move between the clamps of the elastic clamp 23). Specifically, for rigid rubber tubes, the pusher plate 24 needs to be connected to the extrusion structure built into its internal body. For sausage soft packaging, the pusher plate 24 directly abuts against its end, and the material is pushed to the discharge port 21 at the front opening by squeezing the sausage soft packaging forward. When the rubber tube is installed on the rubber tube fixing seat 2, the front ends of the left piston rod 41 and the right piston rod 51 are respectively connected to the pusher plate 24 of the corresponding side rubber tube fixing seat 2. When the piston rod moves forward, it can push the material in the rubber tube to be discharged from the discharge port 21.

[0036] This invention also considers that low-viscosity materials are prone to backflow or dripping after the feeding stops, and therefore a one-way check valve 8 is installed on the equipment. For example... Figure 4As shown, the Y-shaped tee 71 is connected to the discharge port 21 via a one-way check valve 8. The one-way check valve 8 includes a hollow valve body 81, a piston rod valve core 82, and a return spring 83. One end of the hollow valve body 81 is connected to the discharge port 21, and the other end is connected to the inlet of the Y-shaped tee 71. One end of the return spring 83 is fixed inside the hollow valve body 81, and the other end is fixedly connected to the piston rod valve core 82. The return spring 83 provides a preload force to push the piston rod valve core 82 towards the discharge port 21, meaning the spring is always in a pre-compressed state. In this embodiment, the return spring... Spring 83 is arranged parallel to the material flow direction and applies a force to piston rod valve core 82 in the direction of discharge port 21. When the material in the rubber tube is pushed out, the pressure of the material overcomes the preload of return spring 83 and pushes piston rod valve core 82 to move towards the Y-type tee 71, so that it is located in the middle of the valve body, and the material can be discharged smoothly. When the pushing stops, the material pressure disappears, and the preload of return spring 83 pushes piston rod valve core 82 back, so that it fits tightly against and covers the end face of discharge port 21, forming a reliable seal and effectively preventing material backflow and leakage.

[0037] The one-way check valve 8 effectively controls the flow of material during the discharge process to the static mixer 72, preventing low-viscosity material from dripping into subsequent mixing stages after the material feeding stops, thus disrupting the 1:1 material ratio and further enhancing the material feeding effect of the two-component system of this invention. It also prevents backflow of material within the Y-shaped tee, avoiding pipeline blockage and ensuring smooth operation in subsequent applications. It should be noted that the preload of the return spring 83 is greater than the static pressure generated by the material inside the cartridge when stationary, ensuring reliable valve core closure during shutdown and preventing dripping backflow. Simultaneously, the preload is less than the normal operating pressure of the material during feeding, allowing the piston rod valve core 82 to be easily opened for discharge. If the preload is too small, the spring will be easily compressed during feeding, failing to prevent dripping; if the preload is too large, it will significantly increase the pressure demand during feeding, leading to poor material discharge.

[0038] Furthermore, the piston rod valve core 82 is made of polytetrafluoroethylene (PTFE), a material with excellent self-lubricating properties that significantly reduces frictional resistance between the valve core and the valve body, making the valve core move more flexibly and smoothly. At the same time, PTFE also has excellent corrosion resistance and chemical stability, resisting the erosion of various chemical components in the sealing material and extending the service life of the one-way check valve 8.

[0039] To verify the effectiveness of the above technical solution in pushing materials A and B at a 1:1 volume ratio, the present invention was tested under the following conditions: five sets of rigid rubber cylinders were selected, each filled with material A (viscosity 270 mPa·s) and material B (viscosity 10 mPa·s); the effective diameter of the pneumatic cylinder was D=44 mm, and the stroke was L=205 mm (theoretical single-cycle discharge volume is approximately 311 mL, corresponding to a standard capacity of 310 mL for the rigid rubber cylinder); the length-to-diameter ratio of the mixing element 14 and the static mixer 72 was L / D=14; the air supply pressure was 0.5 MPa. Under multiple cycles of material pushing, the volume data of the discharged material were measured, as shown in Table 2. The test results show that the technical solution of the present invention can control the volume ratio deviation of materials A and B within approximately ±0.25%.

[0040] Table 2 Repeatability Tests of Synchronous Propulsion Mechanism at Constant Displacement

[0041] The materials used in the above-mentioned test scenarios are divided into two models based on their foaming ratio and application: Model XC-F (fire extinguishing type), with a foaming ratio of 10, is used for filling and burying oxygen in goaf areas, corners, and high-risk areas for cooling; Model XC-G (gas sealing type), with a foaming ratio of 5, has denser foam, stronger compressive strength, and less shrinkage, and is used for sealing extraction boreholes and plugging local gas leaks. Both have the same base material, only the foaming degree is adjustable, and the 1:1 process remains unchanged. The foaming degree of the material is determined by the amount of air contacted after mixing. Therefore, this invention also includes an airflow regulating channel 9 on the mixing gun for adjusting the foaming ratio. Specifically, an airflow regulating channel 9 is provided at the front end of the static mixer 72 corresponding to the material flow direction, i.e., at the location corresponding to the glue gun nozzle 73, connecting to the internal space of the static mixer 72. The airflow regulating channel 9 is connected to an external compressed air source to introduce compressed air into the mixed material to achieve the foaming function. An adjustment valve 91 is provided on the airflow adjustment channel 9. The adjustment valve 91 adopts a needle valve structure. The opening of the adjustment valve 91 can be adjusted by rotating the valve stem of the needle valve, thereby precisely adjusting the flow rate of compressed air entering the static mixer 72, and thus controlling the foaming ratio of the material, so that the foamed sealing material can adapt to the needs of different construction scenarios.

[0042] In a further proposed solution, considering that the inner cavity of the static mixer 72 serves as a pre-mixing space for materials A and B, long-term use inevitably leads to the generation of colloid residue, which will eventually clog the internal space of the static mixer 72 and affect the durability of the equipment. Therefore, a quick-release connection is adopted between the static mixer 72 and the Y-type tee 71. For example, matching screw-on structures with sealing elements can be installed at the outlet of the Y-type tee 71 and the inlet of the static mixer 72, respectively, to achieve quick installation and disassembly. After each operation, the used static mixer 72 can be unscrewed and replaced with a new spare static mixer 72 for the next operation. Similarly, quick-release connections are also adopted between the outlet 21 of the glue cartridge fixing seat 2 and the seat cylinder 22, and between the outlet 21 and the Y-type tee 71, so as to remove the outlet 21 for the installation of the glue cartridge or to replace the outlet 21 that is blocked by material residue.

[0043] Based on the above technical solution, this invention also applies the above-mentioned mixing gun to perform pneumatic synchronous mixing of two-component low-temperature foamed sealing material in a specific coal mine goaf sealing construction scenario. The implementation process of this method includes the following steps: Step one: The operator first explores and locates the air leakage channels in the goaf of the mine, determining their specific location, shape, and size. Based on the exploration results, due to the large area to be sealed, the operator selects two sausage-shaped soft-pack rubber tubes containing component A (polyol component) with a viscosity of 270 mPa·s and component B (isocyanate component) with a viscosity of 10 mPa·s. Each tube has a capacity of 600 mL. After opening the front end of the tube, the operator installs it into the tube fixing seat 2 on the left and right sides of the mixing gun, connecting the opening at the front end of the tube to the discharge port 21. For example, the discharge port 21 can be removed first, and the tube can be inserted from the front end of the tube fixing seat 2. The elastic clamp 23 is then used to fix the tube, and the push plate 24 is used to press against the end of the tube to test whether the discharge is normal.

[0044] Step two: After the rubber sleeve is installed, the operator connects the air inlet 31 of the pneumatic balancing chamber 3 to the external air source equipment via a high-pressure air pipe. The preferred working pressure of the external air source is 0.4 to 0.6 MPa. After connection, check the status of each piece of equipment, including whether all connections are well sealed and leak-free, whether the left cylinder 4, right cylinder 5 and their corresponding piston rods are working properly, whether the synchronizing rod 6 is securely connected without looseness, and whether all components of the manifold mixing assembly 7 are installed in place. Only after confirming that all equipment is in normal condition can the next construction operation be carried out.

[0045] Step three: When starting the sealing operation of the air leakage channel, the operator aligns the nozzle 73 of the mixing gun with the entrance of the air leakage channel in the goaf to ensure that the subsequently sprayed sealing material can accurately enter the air leakage channel. Then, the operator turns on the external air source, allowing compressed air to enter the pneumatic balance chamber 3 through the air source inlet 31. Once ready, the operator pulls the trigger, and air is simultaneously distributed to the chambers of the left cylinder 4 and the right cylinder 5, initiating the sealing operation.

[0046] Step four: Since the left cylinder 4 and the right cylinder 5 are identical, the air pressure acting on the left and right piston rods is exactly the same. The synchronizing rod 6 rigidly connects the left piston rod 41 and the right piston rod 51, ensuring that the two piston rods move synchronously with exactly the same displacement. When compressed air pushes the two piston rods forward, the left piston rod 41 and the right piston rod 51 advance synchronously, acting on the rubber cylinder to push out material A and material B simultaneously and in equal amounts.

[0047] Step 5: After materials A and B flow out from the two outlets 21 respectively, they enter the Y-shaped tee 71 and initially converge within it. Then, they enter the static mixer 72 for thorough mixing. Inside the static mixer 72, materials A and B sequentially pass through three mixing element plates: a large-pitch spiral element 74, a small-pitch staggered spiral element 75, and an orifice plate turbulence generator 76. Under the initial mixing of the spiral flow, the enhanced mixing of the bidirectional staggered spirals, and the efficient mixing of the orifice plate turbulence, the two materials reach a uniformly mixed state.

[0048] Meanwhile, since this scenario requires sealing the air leakage channels, the mixing and foaming ratio of the materials is set to 5 times. According to this setting, the operator controls the amount of compressed air introduced through the regulating valve 91 on the airflow regulating channel 9, ensuring the mixed material fully contacts the air according to the set foaming ratio, achieving precise foaming, and finally discharges it to the working surface for sealing. At the end of the construction operation, some small-scale leak detection and repair are required. The construction personnel remove the sausage soft package and replace it with a standard 310ml rigid plastic cartridge containing the same material. Following step one, the rigid plastic cartridge is fixed using the elastic clip 23 and installed on the mixing gun. The entire process does not require equipment replacement and avoids the waste of large amounts of unused material remaining in the large-capacity sausage soft package. After construction is completed, the static mixer 72 is promptly removed to prevent residual material from affecting other parts of the mixing gun's internal piping.

[0049] Through the above technical solution, the pneumatic synchronous mixing gun of the present invention realizes the precise 1:1 ratio of two-component low-temperature foaming sealing material, uniform mixing between materials and controllable foaming function, which can meet the needs of various sealing construction in underground engineering such as mine roadways and tunnels.

[0050] Finally, it should be noted that the above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A pneumatically synchronized dual component low temperature foamed plugging material injection gun for mining operations, characterized in that, include: Gun frame, serving as the supporting skeleton for the mixing gun; Two rubber tube fixing seats are symmetrically installed on both sides of the gun body frame to fix the rubber tube containing the material. The front end of the rubber tube fixing seat is provided with a discharge port. A pneumatic balancing synchronous pushing mechanism, mounted on the gun frame, includes a pneumatic balancing chamber, a left-side cylinder and a right-side cylinder connected to the pneumatic balancing chamber and arranged in parallel on the left and right sides of the gun frame, a left-side piston rod installed in the left-side cylinder, a right-side piston rod installed in the right-side cylinder, and a synchronous connecting rod rigidly connecting the left-side piston rod and the right-side piston rod; the pneumatic balancing chamber is provided with an air source inlet connected to an external air source; the left-side cylinder and the right-side cylinder have the same structure and cylinder diameter; the left-side piston rod and the right-side piston rod are used to push the material in the rubber cylinder out of the discharge port. The confluence mixing assembly includes a Y-shaped tee connected to the discharge port and a static mixer connected in series with the outlet of the Y-shaped tee. The static mixer is hollow inside and is provided with several mixing elements to guide the flow of materials for thorough mixing. The front end of the static mixer is provided with a glue gun nozzle.

2. The pneumatic synchronous mixing and injecting gun of two-component low-temperature foaming plugging material for mine of claim 1, characterized in that, The rubber tube fixing seat includes a hollow seat, an elastic clamp disposed inside the seat, and a push plate movably disposed inside the seat and moving along the axial direction of the seat. The elastic clamp is used to clamp the rubber tube inside the seat. The push plate is connected to the front end of the left piston rod or the right piston rod and can be axially pushed between the elastic clamps.

3. The pneumatic synchronous mixing gun for a two-component low-temperature foaming sealing material for mining as described in claim 1, characterized in that, The left and right cylinders are connected to the pneumatic balance chamber via air pipes, and the air pipes are equipped with openable and closable air valves.

4. The pneumatic synchronous mixing gun for a two-component low-temperature foaming sealing material for mining as described in claim 1, characterized in that, The static mixer adopts a segmented design. The mixing elements along the material flow direction include: an upstream large-pitch spiral element, a midstream small-pitch staggered spiral element, and a downstream orifice plate turbulence generator. The large-pitch spiral element consists of several unidirectional spiral guide structures installed on the inner wall of the upstream static mixer. The small-pitch staggered spiral element consists of several bidirectional spiral guide structures installed on the inner wall of the static mixer. The orifice plate turbulence generator consists of several baffles with openings vertically installed in the inner cavity of the static mixer, with the openings of adjacent baffles arranged in an alternating pattern.

5. The pneumatic synchronous mixing gun for a two-component low-temperature foaming sealing material for mining as described in claim 4, characterized in that, The length-to-diameter ratio of the static mixer is greater than or equal to 12, and the cavity length occupied by the large-pitch helical element, the small-pitch staggered helical element, and the orifice plate turbulence generator is equal along the axial direction of the static mixer cavity.

6. The pneumatic synchronous mixing gun for a two-component low-temperature foaming sealing material for mining as described in claim 1, characterized in that, The Y-type tee is connected to the discharge port via a one-way check valve. The one-way check valve includes a hollow valve body, a piston rod valve core, and a return spring. One end of the hollow valve body is connected to the discharge port, and the other end is connected to the inlet of the Y-type tee. One end of the return spring is fixed inside the hollow valve body, and the other end is fixedly connected to the piston rod valve core. The return spring provides a preload force to push the piston rod valve core towards the discharge port, so that the piston rod valve core covers the discharge port.

7. The pneumatic synchronous mixing gun for a two-component low-temperature foaming sealing material for mining as described in claim 6, characterized in that, The piston rod valve core is made of polytetrafluoroethylene, which has self-lubricating properties.

8. The pneumatic synchronous mixing gun for a two-component low-temperature foaming sealing material for mining as described in claim 1, characterized in that, The static mixer is connected to the Y-tee using a quick-release connection.

9. A pneumatic synchronous mixing gun for a two-component low-temperature foaming sealing material for mining, as described in any one of claims 1-8, characterized in that, The static mixer has an airflow regulating channel at its front end. The airflow regulating channel is connected to an external compressed air source and is equipped with a regulating valve. The regulating valve is a needle valve structure, and the flow rate of compressed air entering the static mixer is controlled by regulating the opening degree of the valve.

10. A pneumatic synchronous mixing and injection method for a two-component low-temperature foamed sealing material for mining, characterized in that, The application of the mixing gun as described in claim 9 includes the following steps: Step 1: According to the requirements of the construction sealing materials, select rubber tubes filled with material A and material B respectively and insert them into the rubber tube fixing base; Step 2: Connect the pneumatic balancing chamber to an external air source and check the status of each device. Step 3: Aim the mixing gun at the area to be sealed, start the external air source, and the air source enters the pneumatic balance chamber, acting simultaneously on the left and right cylinders. Step four: Under the mechanical locking action of the rigid synchronous connecting rod, the left and right piston rods are driven by the air source synchronously discharged from the pneumatic balance chamber to move synchronously and act on the rubber cylinder to push out material A and material B in equal amounts simultaneously. Step 5: Material A and Material B are pre-mixed in a static mixer via a Y-shaped tee. At the same time, the regulating valve is adjusted to control the amount of air in contact with Material A and Material B according to the set foaming ratio, and the foamed material is discharged to seal the construction area.

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