Teaching aid display device for mathematics education

Abstract

The invention relates to a teaching aid display device for mathematics education, and aims to solve the technical problems that a current mathematics teaching aid sample display device is limited in display type and large in storage occupied space, and samples are prone to being affected by oxidation and discoloration in the storage process, the mathematics teaching aid sample display device comprises a box body, and a plurality of attached display boards are placed in an inner cavity of the box body; the plurality of attached display boards are in sliding connection, first connecting frames are installed on the two sides of the moving plate respectively, the second cover plate is connected to the first connecting frames, a first rotating rod is rotatably installed on the long plate, and a first gear is installed on the first rotating rod; the inner cavity of the cylindrical shell is rotatably connected with a rotating vane, the rotating vane is provided with a second rotating rod, the second rotating rod is provided with a second gear, and the second gear is in meshed connection with the first gear. Operation is convenient, and unfolding and folding switching is rapid; vacuum pumping can inhibit deterioration of the math teaching aid, and the effect of long-term storage of samples is achieved.

Description

Technical Field

[0001] This invention relates to the field of mathematical teaching aids display, specifically to a mathematical teaching aids display device. Background Technology

[0002] The sale and display of math teaching aids (such as geometric models, arithmetic tools, and drawing tool sets) is a key link between production and consumption. It needs to meet the requirements of clear presentation of multiple categories, undamaged protection of samples, efficient use of space, and convenient display and operation. In sales scenarios such as teaching aid stores and education exhibitions, consumers need to intuitively compare the quality (such as materials, craftsmanship, and size) of teaching aids of different categories and specifications. Merchants need to ensure that the samples remain in good condition after long-term display, while avoiding display devices occupying too much space.

[0003] However, existing technologies have the following problems when used: Firstly, the use of single or fixed display structures makes it difficult to simultaneously accommodate multiple math teaching aid samples. Increasing the number of samples to be displayed requires expanding the device's volume, leading to a prominent conflict between display and storage space. Furthermore, samples are prone to mutual interference when being picked up or placed, resulting in poor operational flexibility. Secondly, the lack of reliable sealing and environmental control design allows outside air and moisture to easily penetrate the device, making it prone to oxidation of components such as nicotine in math teaching aids. At the same time, a humid environment accelerates discoloration, making it impossible to guarantee the quality stability of samples after long-term storage. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art, adapt to the needs of reality, and provide a display device for teaching aids in mathematics education, so as to solve the technical problems of the current display devices for mathematics teaching aid samples, such as limited display types, large storage space, and susceptibility to oxidation and discoloration during sample preservation.

[0005] To achieve the objective of this invention, the technical solution adopted is as follows: a mathematical education teaching aid display device is designed, comprising a box body, in which multiple fitted display panels are placed in the inner cavity of the box body and are slidably connected to each other. A transparent frame is inserted into each display panel, and a second cover plate is installed on the upper end of the display panel at the rear end. A first cover plate is detachably installed on the front end of the second cover plate. A long plate is installed at the rear end of the box body, and a movable plate is slidably connected to the rear end of the long plate. First connecting frames are respectively installed on both sides of the upper end of the movable plate, and the upper end of the second cover plate is connected to the first connecting frames. A first rotating rod is rotatably installed on the upper end of the long plate, and a first gear is installed on the first rotating rod. A connecting plate is installed at the end of the long plate, and a cylindrical shell is installed at the end of the connecting plate. A rotating blade is rotatably connected to the inner cavity of the cylindrical shell. A second rotating rod is installed at the upper end of the rotating blade. A second gear is installed at the upper end of the second rotating rod, and the second gear meshes with the first gear. A flexible hose is connected to the end of the cylindrical shell, and the front end of the flexible hose is connected to the rear end of the box.

[0006] In this design, the housing provides a stable platform for the device. Multiple slidingly connected display panels within its interior can be used to categorize and hold various math teaching aid samples. Transparent frames inserted into the display panels securely hold the math teaching aids to prevent shifting, clearly display their features, and provide dust protection. The first and second cover plates are detachably connected; the first cover plate can be removed for display to avoid obstruction, while the housing is sealed for storage.

[0007] The long board, the movable board, and the first connecting frame form a lifting mechanism. Power is transmitted through the first rotating rod and the first gear, causing the display boards to rise and fall synchronously, allowing the stacked display boards to unfold or retract in an orderly manner, reducing space occupation. The air extraction structure, composed of the connecting plate and the cylindrical shell, is linked to the lifting mechanism. The first gear drives the second gear to rotate the vane and generate negative pressure, which extracts air from the box through the hose, creating a vacuum environment and extending the storage period of the math teaching aids.

[0008] Preferably, the upper end of the box has a groove, a connecting pipe is installed above the end of the box, and a one-way valve for air outlet is installed below the end of the box.

[0009] In practical applications, the chamber provides storage space for display boards, positions them for safe storage, prevents them from wobbling, and guides their lifting and sliding to ensure smooth unfolding and folding. The connecting pipe at the end of the chamber can be connected to external humidity control devices to meet the specific storage needs of different math teaching aids. A one-way exhaust valve creates a unidirectional exhaust channel, guiding air out during vacuuming and preventing backflow to maintain a negative pressure environment inside the chamber; when restoring pressure, it can slowly release pressure for safe sample retrieval.

[0010] Preferably, a first sliding groove is provided at the front end of the inner wall of the box groove, a second sliding groove is provided at the rear end of the display panel, a slider is installed at the front end of the display panel, and the slider installed on the front display panel is slidably connected in the first sliding groove, and the slider installed on the rear display panel is slidably connected in the second sliding groove.

[0011] In practical applications, the first slide groove inside the box provides a fixed sliding track for the frontmost display panel. Its front slider is embedded in the rear edge of the groove for stable lifting and lowering, providing a reference for the overall sliding. The second slide groove at the rear of the display panel forms a nested connection with the slider of the rear display panel, ensuring that adjacent display panels remain aligned when lifting and lowering, avoiding misalignment and collision, and ensuring smooth and orderly unfolding and storage.

[0012] Preferably, the upper end of the display board is provided with a placement groove, and the inner walls of the placement groove are respectively provided with first slots on both sides. The two ends of the transparent frame are respectively installed with first inserts, and the first inserts are inserted into the first slots. Mathematical teaching aids are placed between the display board and the transparent frame.

[0013] In practical applications, the placement slots on the display board provide space for math teaching aids, allowing them to be laid out flat and ensuring a complete display. The first slots on both sides of the placement slots cooperate with the first inserts at both ends of the transparent frame, enabling easy assembly and disassembly of the transparent frame and facilitating the replacement of math teaching aids. The transparent frame and display board hold the math teaching aids, both fixing the samples to prevent displacement and allowing observers to clearly view them, while simultaneously isolating them from dust and moisture, protecting the sample quality.

[0014] Preferably, a second connecting frame is installed at the front end of the long plate, a motor is installed at the upper end of the second connecting frame, the upper end of the first rotating rod is connected to the motor drive end, a long groove is opened at the rear end of the long plate, a moving block is inserted into the long groove, a threaded rod is rotatably connected in the long groove, and the threaded rod is threadedly connected to the moving block, the front end of the moving plate is connected to the rear end of the moving block, and the upper end of the threaded rod is connected to the lower end of the first rotating rod.

[0015] In practical applications, the motor drive end is connected to the first rotating rod, providing continuous power to the device. The lifting speed can be controlled by adjusting the rotation speed, reducing operational intensity. The threaded rod in the long slot engages with the moving block, converting rotational motion into linear lifting, thus smoothly moving the moving plate and display panel. The threaded rod connects to the first rotating rod to achieve power reuse; the display panel state can be switched by reversing the motor's direction.

[0016] Preferably, the second cover plate has a second slot at its front end, into which a second insert plate is inserted, and the rear end of the first cover plate is connected to the front end of the second insert plate.

[0017] In practical applications, the second slot of the second cover plate cooperates with the second insert plate to ensure a stable connection between the first and second cover plates, preventing shaking and ensuring the sealing effect of the enclosure. The first cover plate is detachably connected to the second cover plate via the second insert plate, allowing for tool-free insertion and removal, enabling quick installation and removal of the cover plate. When displaying, the first cover plate can be removed to avoid obstruction; when storing, it can be installed to form a complete sealed structure, preventing external debris from entering the enclosure.

[0018] Preferably, a second pipe is installed at the end of the cylindrical shell, a first pipe is installed at the rear end of the box body, the front end of the flexible hose is connected to the front end of the first pipe and the end of the flexible hose is connected to the second pipe, and a third pipe is installed at the rear end of the cylindrical shell, and the third pipe communicates with the inner cavity opened on the inner wall of the cylindrical shell.

[0019] In practical applications, the first and second pipes provide stable interfaces between the hose and the housing / shell, respectively, preventing connection detachment and air leakage, and ensuring airflow transmission is sealed. The flexibility of the hose can adapt to changes in component position during device lifting and lowering, preventing pipe breakage and twisting, and maintaining unobstructed airflow. The third pipe connects to the inner cavity of the shell to form an exhaust channel. The negative pressure generated by the rotating blades quickly exhausts air from the housing through multiple pipes, improving vacuum efficiency and ensuring a stable negative pressure environment inside the housing.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. When displaying various math teaching aid samples, the categorized math teaching aids are first placed one by one into the placement slot of the display board. Then, the first insert plate of the transparent frame is inserted into the first slot of the placement slot, so that the display board and the transparent frame clamp and fix the math teaching aids, preventing them from shifting or wrinkling. At the same time, it ensures that the features of the math teaching aids are clearly visible and that they are dustproof and collision-proof. At this time, all display boards are stacked and stored in the box slot of the box, saving space. Before display, the second insert plate of the first cover plate is pulled out from the second slot of the second cover plate. The motor on the second connecting frame is started. The motor drives the first rotating rod to drive the threaded rod to rotate in the long slot of the long plate. The threaded rod and the moving block's threaded engagement convert the rotational motion into linear motion, driving the moving block, the moving plate and the first connecting frame to move upward, thereby pulling the second cover plate up. Under the nested guidance of the slider and the first and second sliding grooves, multiple stacked display boards unfold smoothly in sequence, forming a layered display state, which is convenient for comparison and viewing, and can be quickly stacked to reduce space when stored.

[0021] When not being displayed, the second insert plate of the first cover plate is inserted into the second slot of the second cover plate to securely connect them. The motor is then started to rotate in the opposite direction, causing the first rotating rod and the threaded rod to rotate in the opposite direction. The moving block drives the moving plate, the first connecting frame, and the cover plate structure to move downwards until the box groove of the box body is sealed, isolating external debris. After sealing, the motor continues to run, and the first gear drives the meshing second gear to rotate. The second rotating rod drives the rotating blade inside the cylinder to rotate, generating negative pressure. Air in the box groove is drawn into the cylinder through the first pipe, the hose, and the second pipe, and then discharged through the third pipe, creating a negative pressure environment in the box groove, inhibiting the oxidation and discoloration of the math teaching aids, and extending their shelf life. Attached Figure Description

[0022] Figure 1 This is a first-view perspective stereoscopic diagram of the present invention; Figure 2 This is a second-view perspective stereoscopic diagram of the present invention; Figure 3 This is a three-dimensional schematic diagram of the box body of the present invention; Figure 4 This is a three-dimensional schematic diagram showing the separation of the display panel and the transparent frame of the present invention; Figure 5This is a three-dimensional schematic diagram of the separation of the first cover plate and the second cover plate of the present invention; Figure 6 This is a cross-sectional view of the long plate of the present invention; Figure 7 This is a three-dimensional schematic diagram of the connection between the flexible hose and the shell of the present invention; Figure 8 This is a cross-sectional view of the cylindrical shell of the present invention.

[0023] In the picture: 100. First cover plate; 110. Box body; 111. First slide groove; 112. Box groove; 120. Second cover plate; 121. Second slot; 130. Connecting pipe; 140. One-way valve for air outlet; 150. Slider; 160. Display board; 161. Placement slot; 162. Second slide rail; 163. First slot; 170. First insert plate; 180. Transparent frame; 190. Second insert plate; 200. First connecting frame; 210. Long plate; 211. Long groove; 220. Second connecting frame; 230. Motor; 240. Moving block; 250. Threaded rod; 260. First gear; 270. First rotating rod; 280. Moving plate; 300. Hose; 310. First pipe; 320. Connecting plate; 330. Shell; 340. Rotating blade; 350. Second pipe; 360. Second rotating rod; 370, Third pipe; 380, Second gear. Detailed Implementation

[0024] The present invention will be further described below with reference to the accompanying drawings and embodiments: Example 1: A mathematical education teaching aid display device, see [link / reference] Figures 1 to 8The device includes a housing 110, with multiple fitted display panels 160 placed inside the housing 110. These panels are slidably connected. A transparent frame 180 is inserted into each display panel 160. A second cover plate 120 is installed on the upper end of the rearmost display panel 160. A first cover plate 100 is detachably installed on the front end of the second cover plate 120. A long plate 210 is installed at the rear end of the housing 110. A movable plate 280 is slidably connected to the rear end of the long plate 210. First connecting frames 200 are installed on both sides of the upper end of the movable plate 280. The upper end of the second cover plate 120 is connected to... The first connecting frame 200 has a first rotating rod 270 rotatably mounted on the upper end of the long plate 210, and a first gear 260 is mounted on the first rotating rod 270; the upper end of the box body 110 has a box groove 112, a connecting pipe 130 is mounted above the end of the box body 110, and an exhaust one-way valve 140 is mounted below the end of the box body 110; the front end of the inner wall of the box groove 112 has a first sliding groove 111, the rear end of the display plate 160 has a second sliding groove 162, the front end of the display plate 160 has a slider 150, and the slider 150 mounted on the front display plate 160 is slidably connected. Within the first slide groove 111, the slider 150 of the rear-mounted display panel 160 is slidably connected to the second slide groove 162; a placement groove 161 is provided at the upper end of the display panel 160, and first slots 163 are respectively provided on both sides of the inner wall of the placement groove 161; first insert plates 170 are respectively installed at both ends of the transparent frame 180, and the first insert plates 170 are inserted into the first slots 163; a math teaching aid is placed between the display panel 160 and the transparent frame 180; a second connecting frame 220 is installed at the front end of the long plate 210, and a motor 230 is installed at the upper end of the second connecting frame 220. The upper end of the rotating rod 270 is connected to the drive end of the motor 230. The rear end of the long plate 210 has a long slot 211, into which a moving block 240 is inserted. A threaded rod 250 is rotatably connected to the long slot 211, and the threaded rod 250 is threadedly connected to the moving block 240. The front end of the moving plate 280 is connected to the rear end of the moving block 240, and the upper end of the threaded rod 250 is connected to the lower end of the first rotating rod 270. The front end of the second cover plate 120 has a second slot 121, into which a second insert plate 190 is inserted. The rear end of the first cover plate 100 is connected to the front end of the second insert plate 190. When displaying samples of various math teaching aids, operators can first classify and organize the samples of different categories and grades, and then place them one by one on multiple independent display boards 160. The placement slots 161 at the top of each display board 160 provide a flat supporting space for the math teaching aids, allowing them to naturally unfold and fully present their shape, color, and texture. After the math teaching aids are properly placed, the first inserts 170 at both ends of the transparent frame 180 are aligned with the first slots 163 on both sides of the inner wall of the placement slots 161 and inserted. At this time, the display board 160 and the transparent frame 180 form a stable clamping structure, firmly confining the math teaching aids between them. This effectively prevents the math teaching aids from shifting or wrinkling during subsequent operations, and the transparency of the transparent frame 180 ensures that the observer can clearly and intuitively view the details of the math teaching aids. It also provides initial protection against dust and contact.

[0025] After the math teaching aids are loaded, all display boards 160 are stored in the slots 112 of the box 110 in a close-fitting, stacked state, saving space. When it is time to display the equipment, simply pull out the second insert 190 connected to the rear end of the first cover 100 from the second slot 121 at the front end of the second cover 120 to quickly remove the first cover 100 and avoid obstructing the display view. Then, start the motor 230 installed on the second connecting frame 220. The drive end of the motor 230 will drive the first rotating rod 270 to rotate synchronously, and the threaded rod 250 connected to the lower end of the first rotating rod 270 will also rotate in the long slot 211 of the long plate 210. Since the threaded rod 250 is threadedly connected to the moving block 240 embedded in the long groove 211, the rotational motion is converted into linear motion here, which drives the moving block 240 to slide upward along the long groove 211. The moving plate 280 connected to the rear end of the moving block 240 also rises synchronously, and then the second cover plate 120 is pulled upward by the first connecting frame 200 on both sides of the upper end of the moving plate 280.

[0026] Under the traction of the second cover plate 120, the connected rear display plate 160 moves upward first. Multiple closely spaced display plates 160 are linked in an orderly manner through the cooperation of sliders 150 and grooves. The sliders 150 of the front display plate 160 are embedded in the first groove 111 on the inner wall of the box groove 112, while the sliders 150 of the rear display plate 160 are embedded in the second groove 162 at the rear end of the previous display plate 160. This nested sliding structure ensures that multiple stacked display plates 160 can unfold smoothly upwards in sequence, ultimately forming a layered display arrangement. This not only provides each mathematical teaching aid sample with an independent display space, avoiding mutual obstruction and interference, and facilitating comparison and viewing by observers, but also allows the display plates 160 to be stacked and stored back into the box groove 112 after the display, significantly reducing the space occupied by the device and facilitating transportation and storage.

[0027] For details, see Figures 1 to 8 A connecting plate 320 is installed at the end of the long plate 210, and a cylindrical shell 330 is installed at the end of the connecting plate 320. A rotating blade 340 is rotatably connected to the inner cavity of the cylindrical shell 330. A second rotating rod 360 is installed at the upper end of the rotating blade 340, and a second gear 380 is installed at the upper end of the second rotating rod 360. The second gear 380 meshes with the first gear 260. A flexible hose 300 is connected to the end of the cylindrical shell 330, and the front end of the flexible hose 300 is connected to the rear end of the box body 110. A second pipe 350 is installed at the end of the cylindrical shell 330, and a first pipe 310 is installed at the rear end of the box body 110. The front end of the flexible hose 300 is connected to the front end of the first pipe 310, and the end of the flexible hose 300 is connected to the second pipe 350. A third pipe 370 is installed at the rear end of the cylindrical shell 330, and the third pipe 370 communicates with the inner cavity opened in the inner wall of the cylindrical shell 330. When there is no need to display the sample of the math teaching aid, the operator first aligns the second insert plate 190 at the rear end of the first cover plate 100 with the second slot 121 of the second cover plate 120 and inserts it to achieve a stable connection between the first cover plate 100 and the second cover plate 120, forming a complete cover plate structure.

[0028] Then, the motor 230 is started and controlled to rotate in the opposite direction. The motor 230 drives the first rotating rod 270 and the threaded rod 250 to rotate in the opposite direction. The moving block 240 slides downward along the long groove 211, and the moving plate 280 and the first connecting frame 200 descend synchronously, pulling the first cover plate 100 and the second cover plate 120 to move downward together until the cover plate structure is completely attached to the upper end of the box 110, completely sealing the box groove 112. This effectively isolates external dust, moisture and pollutants, building a preliminary protective barrier for the mathematical teaching aid sample.

[0029] After the cover plate structure is sealed, the motor 230 continues to run. At this time, the first gear 260 connected to the first rotating rod 270 also rotates. Since the first gear 260 and the second gear 380 mesh with each other, the power is transmitted to the second gear 380, which drives the second rotating rod 360 at its lower end to rotate synchronously, thereby driving the vane 340 in the inner cavity of the cylindrical shell 330 to rotate. The rotation of the vane 340 creates a negative pressure environment in the cylindrical shell 330. The air in the box 112 is then drawn into the inner cavity of the cylindrical shell 330 through the first pipe 310 at the rear end of the box 110, the flexible hose 300, and the second pipe 350 at the end of the cylindrical shell 330 in sequence, and finally discharged to the outside of the device through the third pipe 370 at the rear end of the cylindrical shell 330. Vacuuming can continue until a stable negative pressure environment is formed inside the chamber 112. This environment can effectively inhibit the oxidation reaction of the math teaching aid samples, fundamentally extend the storage period of the math teaching aid samples, and ensure that the samples can maintain their original quality state after long-term storage, providing reliable sample support for subsequent sorting, comparison, research and analysis.

[0030] It should be noted that the motor 230 mentioned in the text is existing technology that can be found. Motor 230 is a conventional servo motor. Its working principle revolves around a closed-loop control logic of signal feedback and deviation correction. The core is to continuously compare the command signal with the actual operating state and adjust the motor output in real time to eliminate deviation, thereby achieving precise control.

[0031] In addition, all components designed in this invention are general standard parts or components known to those skilled in the art. Their structures and principles can be learned by those skilled in the art through technical manuals or conventional experimental methods. They can be fully implemented by those skilled in the art, so there is no need to elaborate. The content protected by this invention does not involve improvements to the internal structure and methods.

[0032] The embodiments disclosed in this invention are preferred embodiments, but are not limited thereto. Those skilled in the art can easily understand the spirit of this invention based on the above embodiments and make different extensions and variations, but as long as they do not depart from the spirit of this invention, they are all within the protection scope of this invention.

Claims

1. A teaching aid display device for mathematics education comprising a box (110), characterized in that, The box (110) cavity is placed with a plurality of display board (160) fit, and a plurality of fit between the display board (160) sliding connection, the display board (160) is inserted into the transparent frame (180), and the upper end of the display board (160) at the rear end is installed with the second cover plate (120), the front end of the second cover plate (120) is detachably installed with the first cover plate (100), the rear end of the box (110) is installed with the long plate (210), the rear end of the long plate (210) is slidingly connected with the moving plate (280), the upper end of the moving plate (280) is installed with the first connecting frame (200) on both sides respectively, and the upper end of the second cover plate (120) is connected to the first connecting frame (200), the upper end of the long plate (210) is rotatably installed with the first rotating rod (270), and the first rotating rod (270) is installed with the first gear (260); The end of the long plate (210) is installed with the connecting plate (320), the end of the connecting plate (320) is installed with the cylinder shell (330), the inner cavity of the cylinder shell (330) is rotatably connected with the rotating blade (340), the upper end of the rotating blade (340) is installed with the second rotating rod (360), the upper end of the second rotating rod (360) is installed with the second gear (380), and the second gear (380) is engaged with the first gear (260), the end of the cylinder shell (330) is connected with the hose (300), and the front end of the hose (300) is connected to the rear end of the box (110).

2. A mathematical educational teaching aid display apparatus as claimed in claim 1, wherein, The upper end of the box (110) is provided with a box groove (112), the end of the box (110) is installed with a connecting pipe (130) above, and the end of the box (110) is installed with an air outlet check valve (140) below.

3. A mathematical educational teaching aid display apparatus as claimed in claim 2, wherein The front end of the inner wall of the box groove (112) is provided with a first sliding groove (111), the rear end of the display board (160) is provided with a second sliding groove (162), the front end of the display board (160) is installed with a sliding block (150), and the sliding block (150) installed on the display board (160) in front is slidingly connected in the first sliding groove (111), and the sliding block (150) installed on the display board (160) at the rear is slidingly connected in the second sliding groove (162).

4. A mathematical educational teaching aid display device as claimed in claim 3, characterized in that The upper end of the display board (160) is provided with a placing groove (161), the inner wall of the placing groove (161) is provided with a first insertion slot (163) on both sides respectively, the both ends of the transparent frame (180) are installed with a first insertion plate (170) respectively, and the first insertion plate (170) is inserted into the first insertion slot (163), and the display board (160) and the transparent frame (180) are placed with a mathematical teaching aid.

5. A mathematical educational teaching aid display apparatus as claimed in claim 1, wherein, The long plate (210) front end is equipped with the second connecting frame (220), the second connecting frame (220) upper end is equipped with motor (230), the first rotary lever (270) upper end is connected to motor (230) drive end, the long plate (210) rear end is set up long slot (211), the long slot (211) inserts the moving block (240), the long slot (211) is rotatably connected with threaded rod (250) inside, and threaded rod (250) is connected with moving block (240) in screw thread, the moving plate (280) front end is connected to moving block (240) rear end, threaded rod (250) upper end is connected to the first rotary lever (270) lower end.

6. A mathematical educational teaching aid display apparatus as claimed in claim 1, wherein, The second cover plate (120) front end is set up second slot (121), the second slot (121) inserts the second plug-in board (190) inside, the first cover plate (100) rear end is connected to the second plug-in board (190) front end.

7. A mathematical educational teaching aid display apparatus as claimed in claim 1, wherein, The barrel shell (330) end is equipped with the second pipeline (350), the box (110) rear end is equipped with the first pipeline (310), the hose (300) front end is connected to the first pipeline (310) front end, and the hose (300) end is connected to the second pipeline (350), the barrel shell (330) rear end is equipped with the third pipeline (370), and the third pipeline (370) is communicated with the inner cavity of the inner wall of the barrel shell (330).

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