A coal mine return air roadway reinforcing gunite machine

Abstract

This invention discloses a shotcrete machine for reinforcing coal mine return airway, belonging to the technical field of shotcrete machines. The shotcrete machine includes a mixing hopper, a mixing hood, and a quantitative dispensing seat connected sequentially from top to bottom. The mixing hood and the quantitative dispensing seat form a two-stage air injection structure. This invention injects compressed air during the mortar mixing stage, causing air bubbles to form inside the mortar, thereby improving the mixing effect of the raw materials in the mortar and increasing the fluidity of the mortar, thus reducing the mortar adhering to the walls inside the device. By adopting a two-stage air injection structure, compressed air is injected in both the mixing and conveying stages. The compressed air in the two stages is used to improve the mortar mixing effect and the mortar fluidity, respectively, thereby effectively reducing the probability of equipment blockage and ensuring a continuous supply of mortar. This solves the problem of easy blockage of shotcrete machines during the shotcrete process in underground coal mine roadways.

Description

Technical Field

[0001] This invention belongs to the field of shotcrete machine technology, specifically a shotcrete machine for reinforcing coal mine return airway. Background Technology

[0002] Shotcrete support is a key technology for reinforcing underground roadways in coal mines. In the unique working environment of coal mine return airways, equipment faces severe challenges such as confined space, humid air, and high concentrations of methane and dust. Traditional shotcrete machines, especially those used in wet shotcrete processes, have long suffered from a prominent problem during operation: the mixed mortar is prone to adhering to the walls, depositing, and scaling along the internal transport path of the equipment, ultimately leading to blockage of the flow channels.

[0003] This blockage is mainly caused by the following reasons: First, in order to meet the requirements of pumping and spraying, the sprayed mortar is usually designed to be in a high-concentration, high-viscosity state, which has strong inherent adhesion; second, when the materials are not mixed sufficiently, the cement particles fail to completely disperse and coat the aggregate, forming local clumps with greater viscosity; third, the underground ambient temperature may be low, and the equipment may not be thoroughly cleaned in time when it is shut down, which will accelerate the solidification and adhesion of the mortar, ultimately causing frequent blockages in the equipment. Summary of the Invention

[0004] This invention overcomes the shortcomings of the prior art and proposes a shotcrete machine for reinforcing coal mine return airway; it solves the problem of easy clogging of shotcrete machines during the shotcrete process in underground coal mine roadways.

[0005] This invention is achieved through the following technical solution:

[0006] A shotcrete machine for reinforcing coal mine return air roadways includes a mixing hopper, a mixing hood, and a quantitative dispensing seat connected sequentially from top to bottom. The mixing hood has a cavity communicating with the mixing hopper, and a through groove is provided at the bottom end of the cavity. An extension hood is fixedly installed on the outer wall of the mixing hood. A water guide groove is provided through the middle of the extension hood. A connecting groove is provided inside the mixing hood. A water outlet groove is provided on the lower surface of the mixing hood. The water guide groove, the connecting groove, and the water outlet groove are connected sequentially. A piston chamber is fixedly installed at the bottom end of the extension hood, and the top end of the piston chamber is connected to the water guide groove. A piston head is slidably arranged inside the piston chamber. An air inlet groove is provided through the top end of the inner side wall of the piston chamber.

[0007] The top of the quantitative dispensing seat is rotatably connected to a connecting seat, which is fixedly installed at the bottom of the mixing hood. A material trough adapted to the through groove is provided through the middle of the connecting seat. A support seat is rotatably installed at the bottom of the quantitative dispensing seat. Both the through groove and the material trough are arc-shaped structures. Multiple transfer grooves are arranged around the inside of the quantitative dispensing seat. The cross-sectional area of ​​both the through groove and the material trough is larger than the cross-sectional area of ​​the transfer groove.

[0008] Furthermore, a water distribution seat is fixedly installed in the middle of the water guide channel. The water distribution seat has two symmetrically distributed L-shaped grooves inside. The tops of the two L-shaped grooves are respectively connected to the two ends of the water guide channel. One-way valves are fixedly installed at the bottom of the two L-shaped grooves. The two one-way valves are connected to the inside of the piston chamber, and the two one-way valves are in opposite directions. The two L-shaped grooves and the two one-way valves form a one-way water supply structure in the water guide channel and the piston chamber.

[0009] Furthermore, a connecting rod is rotatably connected to the bottom end of the piston head, and the connecting rod is located inside the piston chamber. The bottom end of the connecting rod is rotatably connected to a crank via a pin. A drive motor is fixedly installed at the bottom outer side of the piston chamber, and the output shaft of the drive motor passes through the bottom end of the piston chamber and is fixedly connected to the middle of the crank. The drive motor, crank, and connecting rod constitute the power source of the piston head.

[0010] Furthermore, the mixing hood is equipped with an annular air groove, and the axis of the annular air groove coincides with the axis of the water outlet groove. The inner sidewall of the annular air groove is surrounded by multiple secondary air holes, and all of the secondary air holes are connected to the inside of the water outlet groove. The secondary air holes are used to inject air into the pre-mixed mortar to accelerate the flow of the mortar.

[0011] Furthermore, an annular baffle is fixedly installed at the bottom of the inner wall of the water outlet trough, and the annular baffle is located outside the secondary air hole. The cross-section of the annular baffle is "┌" shaped, and multiple square air grooves are arranged around the bottom of the annular baffle. The annular baffle is used to restrict the mortar from blocking the secondary air hole.

[0012] Furthermore, it also includes an air compressor, with air guide pipes fixedly installed on the outer sides of both the annular air groove and the air inlet groove, and the air guide pipes are connected to the output end of the air compressor. A one-way air valve is installed between the air guide pipes and the air compressor.

[0013] Furthermore, a discharge pipe is installed through the lower surface of the support base, and a spraying pipe is fixedly connected to the bottom end of the discharge pipe; the spraying pipe is a flexible rubber hose, and its end is equipped with a metal nozzle to guide the mortar to be sprayed out.

[0014] Furthermore, a primary water pipe is fixedly installed at one end of the extension cover, and the primary water pipe is connected to the water guide channel; a secondary water pipe is fixedly installed in the middle of the discharge pipe, and the secondary water pipe is connected to the inside of the discharge pipe; the other ends of the primary water pipe and the secondary water pipe are both connected to the water tank.

[0015] Furthermore, it also includes a track base, with the mixing hopper fixed to the track base by multiple detachable columns, and the water tank and air compressor directly fixed to the main support of the track base by bolts.

[0016] Furthermore, a power main shaft is rotatably connected to the middle of the support base, and the power main shaft passes through the quantitative dispensing seat, the mixing hood and the mixing hopper; an agitator is fixedly installed at the top of the power main shaft, and the agitator is located inside the mixing hopper; the middle of the power main shaft is fixedly connected to the quantitative dispensing seat; a power motor is fixedly installed at the bottom of the support base, and the output shaft of the power motor is drivenly connected to the bottom end of the power main shaft.

[0017] The beneficial effects of this invention compared to the prior art are as follows:

[0018] 1. This invention improves the mixing effect of the raw materials in the mortar by injecting compressed air during the mortar mixing stage, thereby forming air bubbles inside the mortar and improving the mortar's fluidity. This reduces the mortar's adhesion to the walls of the device. By adopting a two-stage air injection structure, compressed air is injected in both the mixing and conveying stages. The compressed air in the two stages is used to improve the mortar mixing effect and improve the mortar's fluidity, respectively, thereby effectively reducing the probability of equipment blockage and ensuring a continuous supply of mortar, thus ensuring the smooth progress of shotcreting operations in the tunnel.

[0019] 2. This invention achieves the mixing of mortar and water by employing a piston-type pulse water supply method. It utilizes intermittent high-pressure water flow to impact the mortar material, thereby improving the mixing effect and conveying speed of the mortar material. Furthermore, by forcibly mixing compressed air and water, the amount of air bubbles generated is increased, further improving the smoothness of mortar material conveying and reducing the mortar material adhering to the wall. Moreover, the piston-type water supply method can ensure a stable water supply volume and pressure, thereby ensuring that the mortar is sprayed into the tunnel in the optimal ratio during subsequent shotcreting operations, thus improving the final work quality. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the overall structure of the present invention;

[0021] Figure 2 This is a schematic diagram of the structure of the water tank, mixing hopper and mixing hood of the present invention;

[0022] Figure 3 This is a schematic diagram of the structure of the mixing hopper, mixing hood, and quantitative dispensing seat of the present invention. Figure 1 ;

[0023] Figure 4 This is an exploded view of the mixing hopper, mixing hood, and quantitative dispensing seat of the present invention;

[0024] Figure 5 This is a schematic diagram of the mixing hood structure of the present invention. Figure 1 ;

[0025] Figure 6 This is a schematic diagram of the mixing hood structure of the present invention. Figure 2 ;

[0026] Figure 7 This is a cross-sectional schematic diagram of the mixing hood structure of the present invention;

[0027] Figure 8 For the present invention Figure 7 Enlarged schematic diagram of the structure at point A in the middle;

[0028] Figure 9 This is a schematic diagram of the internal flow direction of the piston chamber structure of the present invention;

[0029] Figure 10 This is a schematic diagram of the water distribution seat structure of the present invention.

[0030] In the diagram: 1. Track base; 11. Water tank; 12. Air compressor; 2. Mixing hopper; 3. Mixing hood; 31. Extension hood; 311. Water guide channel; 3111. Primary water pipe; 312. Connecting channel; 313. Water outlet channel; 3131. Annular air channel; 3132. Secondary air vent; 3133. Annular baffle; 3134. Square air channel; 314. Water distribution seat; 3141. L-shaped channel; 3142. Single... 315. Piston chamber; 3151. Piston head; 3152. Air inlet groove; 3153. Connecting rod; 3154. Crank; 3155. Drive motor; 32. Through groove; 4. Quantitative dispensing seat; 41. Connecting seat; 411. Material trough; 42. Support seat; 421. Discharge pipe; 422. Shotcrete pipe; 423. Secondary water pipe; 43. Power spindle; 431. Power motor; 44. Agitator blade. Detailed Implementation

[0031] To make the technical problems to be solved, the technical solutions, and the beneficial effects of this invention clearer, the invention will be further described in detail with reference to the embodiments and accompanying drawings. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. The technical solutions of this invention are described in detail below with reference to the embodiments and accompanying drawings, but the scope of protection is not limited thereto.

[0032] See Figures 1 to 10 This embodiment proposes a shotcrete machine for reinforcing coal mine return air roadways. In essence, it is a shotcrete machine that uses the injection of compressed air to improve the mixing effect of mortar and enhance the fluidity of mortar inside the equipment.

[0033] In terms of specific structural installation, the structural body can be constructed according to the inventive concept of this embodiment; no particular limitations are imposed in this embodiment. In this embodiment, a shotcrete machine for reinforcing coal mine return air roadways includes:

[0034] The track base 1 has a water tank 11 and an air compressor 12 installed on it. The track base 1 serves as the mobile base and load-bearing platform for the whole machine. It is equipped with a motor and engine as the power source, which can ensure that the equipment can move smoothly in the return air roadway of the coal mine. The water tank 11 and the air compressor 12 are directly fixed to the main support of the track base 1 by bolt fastening.

[0035] The mixing hopper 2 is fixedly installed above the track base 1. A vibrating motor is fixedly installed on the outer wall of the mixing hopper 2. The mixing hopper 2 is fixed to the track base 1 by multiple detachable columns. It is used to achieve the initial mixing of mortar raw materials. The bottom of the mixing hopper 2 is provided with a conical structure for easy material discharge.

[0036] A mixing hood 3 is fixedly installed at the bottom of the mixing hopper 2. The middle part of the mixing hood 3 is provided with a cavity that communicates with the bottom of the mixing hopper 2, and a through groove 32 is provided through the bottom of the cavity. An extension hood 31 is fixedly installed on the outer wall of the mixing hood 3. A water guide groove 311 is provided through the middle of the extension hood 31. A connecting groove 312 is provided inside the mixing hood 3. A water outlet groove 313 is provided on the lower surface of the mixing hood 3. The water guide groove 311, the connecting groove 312 and the water outlet groove 313 are connected in sequence. A piston chamber 315 is fixedly installed at the bottom of the extension hood 31, and the top of the piston chamber 315 communicates with the water guide groove 311. A piston head 3151 is slidably installed inside the piston chamber 315. An air inlet groove 3152 is provided through the top of the inner side wall of the piston chamber 315.

[0037] Connecting rod 3153 is rotatably mounted at the bottom end of piston head 3151 and located inside piston chamber 315. Crank 3154 is rotatably mounted at the bottom end of connecting rod 3153 via a pin. Drive motor 3155 is fixedly mounted at the bottom outer side of piston chamber 315, and the output shaft of drive motor 3155 passes through the bottom end of piston chamber 315 and is fixedly connected to the middle of crank 3154. Drive motor 3155, crank 3154 and connecting rod 3153 constitute the power source of piston head 3151.

[0038] The water distribution seat 314 is fixedly installed in the middle of the water guide channel 311. Inside the water distribution seat 314 are two symmetrically distributed L-shaped grooves 3141. The top ends of the two L-shaped grooves 3141 are connected to the two ends of the water guide channel 311, respectively. A one-way valve 3142 is fixedly installed at the bottom end of each of the two L-shaped grooves 3141. Both one-way valves 3142 are connected to the inside of the piston chamber 315, and their directions are opposite. The two L-shaped grooves 3141 and the two one-way valves 3142 together form the water guide channel 311 and the piston chamber 315. The internal one-way water supply structure has a reserved groove at the top of the extension cover 31 for installing the water distribution seat 314. After the water distribution seat 314 is installed, the water guide channel 311 is divided into two parts with the piston chamber 315 as the center. The water distribution seat 314 and the piston chamber 315 cooperate to form a pulse delivery pump. When the piston head 3151 returns, the one-way valve 3142 on the inlet side opens to draw water and simultaneously draw in air. When the piston head 3151 advances, the one-way valve 3142 on the inlet side closes and the one-way valve 3142 on the outlet side opens to discharge the mixed gas-liquid fluid.

[0039] An annular air groove 3131 is located inside the mixing hood 3, and the axis of the annular air groove 3131 coincides with the axis of the water outlet groove 313. The inner sidewall of the annular air groove 3131 is surrounded by multiple secondary air holes 3132, and the multiple secondary air holes 3132 are all connected to the interior of the water outlet groove 313. The secondary air holes 3132 are used to inject air into the pre-mixed mortar for a second time to accelerate the flow of the mortar.

[0040] An annular baffle 3133 is fixedly installed at the bottom of the inner wall of the water outlet trough 313 and located outside the secondary air hole 3132. The cross-section of the annular baffle 3133 is "┌" shaped. Multiple square air grooves 3134 are arranged around the bottom of the annular baffle 3133. The annular baffle 3133 is used to limit the mortar from blocking the secondary air hole 3132. The secondary air hole 3132 can not only directly inject compressed air into the mortar raw material to improve the mortar mixing effect, but also keep the inside of the device under positive pressure to ensure the smooth discharge of mortar.

[0041] Both the outer sides of the annular air groove 3131 and the air inlet groove 3152 are fixedly equipped with air guide pipes, and the air guide pipes are connected to the output end of the air compressor 12. A one-way air valve is installed between the air guide pipes and the air compressor 12.

[0042] The quantitative dispensing seat 4 is located below the mixing hood 3. A connecting seat 41 is rotatably installed on the top of the quantitative dispensing seat 4. The connecting seat 41 is fixedly installed at the bottom of the mixing hood 3 and has a material trough 411 adapted to the through groove 32 through its middle. A support seat 42 is rotatably connected to the bottom of the quantitative dispensing seat 4. The support seat 42 is fixedly installed above the track base 1. A discharge pipe 421 is installed through the lower surface of the support seat 42. Sliding sealing structures are provided between both ends of the quantitative dispensing seat 4 and the connecting seat 41 and the support seat 42 to ensure the sealing effect of the device.

[0043] The spray pipe 422 is fixedly installed at the bottom end of the discharge pipe 421. The spray pipe 422 is a flexible rubber hose with a metal nozzle at its end for guiding the mortar to be sprayed out.

[0044] The primary water pipe 3111 is fixedly installed at one end of the extension cover 31 and connected to the water guide channel 311.

[0045] The secondary water pipe 423 is fixedly installed in the middle of the discharge pipe 421 and is connected to the inside of the discharge pipe 421. The primary water pipe 3111 and the secondary water pipe 423 are both connected to the water tank 11.

[0046] The power spindle 43 is rotatably mounted in the middle of the support base 42 and passes through the quantitative dispensing seat 4, the mixing cover 3 and the mixing hopper 2. The top of the power spindle 43 is fixedly mounted with a stirring blade 44, which is located inside the mixing hopper 2. The middle of the power spindle 43 is fixedly connected to the quantitative dispensing seat 4.

[0047] The power motor 431 is fixedly installed below the support base 42, and the output shaft of the power motor 431 is connected to the bottom end of the power main shaft 43 for transmission.

[0048] Both the through groove 32 and the material trough 411 are arc-shaped structures. Multiple transfer grooves are arranged around the inside of the quantitative material distribution seat 4. The cross-sectional area of ​​both the through groove 32 and the material trough 411 is larger than the cross-sectional area of ​​the transfer grooves.

[0049] When using the shotcrete machine for reinforcing coal mine return air roadways according to this embodiment, the device moves within the coal mine return air roadway via the tracked base 1. After the device moves to the work area, the operator puts the weighed cement, sand, quick-setting agent, and other dry materials into the mixing hopper 2 and simultaneously starts the power motor 431. The power motor 431 drives the power main shaft 43 to rotate, and the power main shaft 43 drives the stirring blade 44 to rotate. The stirring blade 44 performs strong mechanical stirring in the mixing hopper 2, initially mixing the dry mortar materials. During the mixing process, a small amount of water is added to the mixing hopper 2 to improve the mixing effect of the dry mortar materials while reducing dust generation.

[0050] During the mixing process, some of the initially mixed dry materials pass through the through trough 32 and the material trough 411 and fall into the transfer trough inside the quantitative material distribution seat 4. At this time, the quantitative material distribution seat 4 rotates with the power main shaft 43 and drives the dry materials to move through the transfer trough until the transfer trough moves to below the opening of the water outlet trough 313.

[0051] During the mixing and conveying of the dry powder, the drive motor 3155 drives the crank 3154 and connecting rod 3153 to move, causing the piston head 3151 to reciprocate inside the piston chamber 315. The return stroke of the piston head 3151 in the piston chamber 315 generates negative pressure. This negative pressure causes a one-way valve 3142 to open, drawing water from the water tank 11 through the water guide trough 311 and the first-stage water pipe 3111. This water then enters the piston chamber 315 and is briefly stored. During this process, the air compressor 12 starts and compresses air through... The air pipe delivers compressed air to the air inlet 3152. Under negative pressure, the piston chamber 315 draws in compressed air. At this time, the compressed air and water are forcibly mixed in the piston chamber 315 and form a large number of bubbles. Then, the piston head 3151 moves in the opposite direction to generate thrust, so that the two one-way valves 3142 switch states. At this time, the mixed gas-liquid fluid passes through the other one-way valve 3142 and enters the connecting groove 312. Then, it enters the transfer groove in the quantitative material distribution seat 4 through the water outlet 313 and is forcibly mixed with the mortar raw materials that have been initially mixed in the transfer groove.

[0052] After the mortar raw materials in the transfer trough are forcibly mixed with the gas-liquid fluid to form wet mortar, the compressed air generated by the air compressor 12 enters the annular air groove 3131 through the air guide pipe, and then is injected downward into the wet mortar through multiple secondary air holes 3132. The wet mortar is forcibly sheared under the action of air blowing, and at the same time, the pressure in the transfer trough rises. Then the quantitative dispensing seat 4 continues to rotate, and moves the pressurized wet mortar to the top of the discharge pipe 421 through the transfer trough. At this time, the wet mortar enters the discharge pipe 421 under the action of gravity and air pressure. At this time, the water in the water tank 11 is mixed with the wet mortar for the last time through the secondary water pipe 423, and the mortar is pressurized and transported to the spray pipe 422 by water pressure and compressed air. At this time, the operator can adjust the angle of the spray pipe 422 to realize the spraying operation of mortar.

[0053] It should be noted that in this embodiment, the water tank 11 is equipped with a pressure-adjustable water pump, which can inject pressurized water into the secondary water pipe 423 to achieve pressurized spraying of mortar. In this embodiment, the mixing ratio of mortar raw materials and water adopts the publicly available technology.

[0054] It should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This way of describing the specification is only for clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

[0055] The detailed descriptions listed above are merely specific descriptions of feasible implementation methods of this application and are not intended to limit the scope of protection of this application. All equivalent implementation methods or modifications made without departing from the spirit of the art of this application should be included within the scope of protection of this invention.

Claims

1. A shotcrete machine for reinforcing coal mine return air roadways, characterized in that, The system includes a mixing hopper (2), a mixing hood (3), and a quantitative dispensing seat (4) connected sequentially from top to bottom. The mixing hood (3) has a cavity communicating with the mixing hopper (2), and a through groove (32) is provided at the bottom end of the cavity. An extension hood (31) is fixedly installed on the outer wall of the mixing hood (3), and a water guide groove (311) is provided in the middle of the extension hood (31). A connecting groove (312) is provided inside the mixing hood (3). The lower surface is provided with a water outlet groove (313), the water guide groove (311), the connecting groove (312) are connected to the water outlet groove (313) in sequence, the bottom end of the extension cover (31) is fixedly installed with a piston chamber (315), and the top end of the piston chamber (315) is connected to the water guide groove (311). A piston head (3151) is slidably arranged inside the piston chamber (315), and an air inlet groove (3152) is provided through the top end of the inner side wall of the piston chamber (315). A water distribution seat (314) is fixedly installed in the middle of the water guide channel (311). The water distribution seat (314) has two symmetrically distributed L-shaped grooves (3141) inside. The tops of the two L-shaped grooves (3141) are respectively connected to the two ends inside the water guide channel (311). A one-way valve (3142) is fixedly installed at the bottom of each of the two L-shaped grooves (3141). Both one-way valves (3142) are connected to the inside of the piston chamber (315), and the two one-way valves (3142) are in opposite directions. The two L-shaped grooves (3141) and the two one-way valves (3142) form a one-way water supply structure in the water guide channel (311) and the piston chamber (315). The top of the quantitative dispensing seat (4) is rotatably connected to a connecting seat (41), which is fixedly installed at the bottom of the mixing hood (3). A material trough (411) adapted to the through groove (32) is provided through the middle of the connecting seat (41). A support seat (42) is rotatably installed at the bottom of the quantitative dispensing seat (4). Both the through groove (32) and the material trough (411) are arc-shaped structures. Multiple transfer grooves are arranged around the inside of the quantitative dispensing seat (4). The cross-sectional area of ​​both the through groove (32) and the material trough (411) is larger than the cross-sectional area of ​​the transfer groove. A discharge pipe (421) is installed through the lower surface of the support base (42), and a spray pipe (422) is fixedly connected to the bottom end of the discharge pipe (421); the spray pipe (422) is a flexible rubber hose, and a metal nozzle is provided at its end to guide the mortar to spray out.

2. The shotcrete machine for reinforcing coal mine return air roadways according to claim 1, characterized in that, A connecting rod (3153) is rotatably connected to the bottom end of the piston head (3151), and the connecting rod (3153) is located inside the piston chamber (315). The bottom end of the connecting rod (3153) is rotatably connected to the crank (3154) via a pin. A drive motor (3155) is fixedly installed on the bottom outer side of the piston chamber (315), and the output shaft of the drive motor (3155) passes through the bottom end of the piston chamber (315) and is fixedly connected to the middle part of the crank (3154). The drive motor (3155), the crank (3154) and the connecting rod (3153) constitute the power source of the piston head (3151).

3. A shotcrete machine for reinforcing coal mine return air roadways according to claim 1, characterized in that, The mixing hood (3) is provided with an annular air groove (3131) inside, and the axis of the annular air groove (3131) coincides with the axis of the water outlet groove (313). The inner side wall of the annular air groove (3131) is surrounded by multiple secondary air holes (3132), and the multiple secondary air holes (3132) are all connected to the inside of the water outlet groove (313). The secondary air holes (3132) are used to inject air into the pre-mixed mortar for a second time to accelerate the flow of the mortar.

4. A shotcrete machine for reinforcing coal mine return air roadways according to claim 3, characterized in that, An annular baffle (3133) is fixedly installed at the bottom of the inner wall of the water outlet trough (313), and the annular baffle (3133) is located outside the secondary air hole (3132). The cross section of the annular baffle (3133) is "┌" shaped. Multiple square air grooves (3134) are arranged around the bottom of the annular baffle (3133). The annular baffle (3133) is used to restrict the mortar from blocking the secondary air hole (3132).

5. A shotcrete machine for reinforcing coal mine return air roadways according to claim 3, characterized in that, It also includes an air compressor (12), and air guide pipes are fixedly installed on the outer sides of the annular air groove (3131) and the air inlet groove (3152). The air guide pipes are connected to the output end of the air compressor (12), and a one-way air valve is installed between the air guide pipes and the air compressor (12).

6. A shotcrete machine for reinforcing coal mine return air roadways according to claim 1, characterized in that, One end of the extension cover (31) is fixedly installed with a primary water pipe (3111), and the primary water pipe (3111) is connected to the water guide channel (311); a secondary water pipe (423) is fixedly installed in the middle of the discharge pipe (421), and the secondary water pipe (423) is connected to the inside of the discharge pipe (421); the other ends of the primary water pipe (3111) and the secondary water pipe (423) are both connected to the water tank (11).

7. A shotcrete machine for reinforcing coal mine return air roadways according to claim 6, characterized in that, It also includes a track base (1), a mixing hopper (2) fixed to the track base (1) by multiple detachable columns, and a water tank (11) and an air compressor (12) directly fixed to the main support of the track base (1) by bolt fastening.

8. A shotcrete machine for reinforcing coal mine return air roadways according to claim 1, characterized in that, A power spindle (43) is rotatably connected to the middle of the support base (42), and the power spindle (43) passes through the quantitative dispensing seat (4), the mixing hood (3) and the mixing hopper (2); a stirring blade (44) is fixedly installed at the top of the power spindle (43), and the stirring blade (44) is located inside the mixing hopper (2), and the middle of the power spindle (43) is fixedly connected to the quantitative dispensing seat (4); a power motor (431) is fixedly installed below the support base (42), and the output shaft of the power motor (431) is connected to the bottom end of the power spindle (43) for transmission.

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