A clog-resistant vibrating feeder

Abstract

This utility model relates to the field of feeding machine technology, specifically disclosing an anti-clogging vibrating feeder. The anti-clogging vibrating feeder includes a main unit, which includes a feeding box and a vibrating box on one side of the feeding box. The feeding box and the vibrating box are fixedly connected to each other by a fixing plate. The driving mechanism consists of a cavity, a through hole, a mounting plate, two pairs of damping media, a first buffer spring, a placement plate, a mounting platform, a vibrating motor, a first rotating ring, a pulley, and a second rotating ring. The damping media on the mounting plate, the first buffer spring, and the second buffer spring in the eccentric vibration mechanism can effectively absorb and buffer the vibration energy during equipment operation, reducing the vibration and noise of the equipment itself. This not only reduces the impact of equipment operation on the surrounding environment and creates a more comfortable working environment for operators, but also reduces equipment wear caused by vibration and extends the service life of the equipment.

Description

Technical Field

[0001] This utility model relates to the field of feeder technology, specifically to an anti-clogging vibration feeder. Background Technology

[0002] Dual mass feeders are widely used in feeding systems for various materials such as lumps, granules, and powders in industries such as metallurgy, coal, chemical building materials, and power. Their main function is to transfer materials from the silo to downstream equipment or production lines through vibration.

[0003] Traditional vibrating feeders have poor vibration stability and uniformity. Due to unreasonable vibration structure design, vibration energy cannot be evenly and effectively transferred to the material, resulting in uneven and discontinuous feeding during the material conveying process. This makes it difficult to meet the strict requirements of high-precision production processes for material conveying stability and continuity. Furthermore, when conveying materials with high moisture content, high viscosity, or uneven particle size, the material is prone to accumulate and stick in the feeder's trough, discharge port, and other parts, leading to frequent blockages. Utility Model Content

[0004] In view of the shortcomings of the prior art, this utility model provides an anti-clogging vibrating feeder to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, this utility model provides the following technical solution: an anti-clogging vibrating feeder, comprising: a main unit, the main unit including a feeding box and a vibrating box on one side of the feeding box, the feeding box and the vibrating box being fixedly connected to each other by a fixing plate, two pairs of hexagonal bolts being fixedly connected to one side of the inside of the fixing plate, a tension screen being provided inside the feeding box, hook seats being fixedly connected to both the left and right sides of the feeding box and the vibrating box, several mounting blocks being fixedly connected to one side of the feeding box, a driving mechanism being provided inside the vibrating box, a disc cam mechanism being provided inside the feeding box, and an eccentric vibration mechanism being provided on one side of the disc cam mechanism.

[0006] Preferably, the driving mechanism includes a cavity located on the side opposite to the tension screen and connected to a vibrating box. The vibrating box has through holes on its left and right sides. A mounting plate is fixedly connected inside the vibrating box. Two pairs of damping media are fixedly connected to the upper surface of the mounting plate. A first buffer spring is movably connected to the upper surface of the damping media. A placement plate is fixedly connected to the output end of the upper surface of the first buffer spring. Mounting platforms are fixedly connected to the left and right sides of the placement plate. A vibration motor is fixedly connected inside the mounting platform. A first rotating ring is rotatably connected to the left and right sides of the vibration motor. A pulley is rotatably connected to the outer wall of the first rotating ring, and a second rotating ring is rotatably connected to the inside of the pulley.

[0007] Preferably, the disc cam mechanism includes a connecting shaft, which is positioned on the left and right sides of the inner wall of the feeding box. A T-shaped plate is fixedly connected to one side of the pair of connecting shafts. Sliding grooves are provided on the upper and lower sides of the T-shaped plate. Sliding rods are slidably connected inside the pair of sliding grooves. A rotating shaft is rotatably connected to the inner wall of the feeding box, and the rotating shaft passes through the interior of the second rotating ring. A cam ring is rotatably connected to the outer wall of the rotating shaft. A connecting rod is fixedly connected to one side of the pair of sliding rods, and a circular block is fixedly connected to one side of the connecting rod.

[0008] Preferably, the eccentric vibration mechanism includes a movable rod, which is fixedly connected to one side of a sliding rod. A pressing plate is fixedly connected to one side of the movable rod. A pair of first return springs are movably connected to one side of the pressing plate. A mounting frame is fixedly connected to the output end of one side of the first return springs. An eccentric adjustment plate is provided inside the mounting frame. Second return springs are movably connected to the upper and lower sides of the eccentric adjustment plate, and the second return springs are connected to the inner wall of the mounting frame. A pair of third return springs are movably connected to one side of the mounting frame. A fixed platform is fixedly connected to the output end of one side of the pair of third return springs. A pair of second buffer springs are movably connected to the upper surface of the fixed platform, and the second buffer springs are connected to the tension screen.

[0009] Beneficial effects

[0010] This utility model provides an anti-clogging vibratory feeder. Compared with the prior art, it has the following advantages:

[0011] (1) The material can be preliminarily screened by the tension screen installed in the feeding box to prevent large particles or lumps of material from entering the conveying channel and causing blockage. The eccentric vibration mechanism consists of a moving rod, a pressing plate, a pair of first return springs, a mounting frame, an eccentric adjusting plate, a second return spring, a pair of third return springs, a fixed platform, and a pair of second buffer springs. The parts work together to generate continuous and regular vibration, which shakes off the material attached to the trough, feeding port, etc., so as to promote the smooth conveying of materials, greatly reduce the downtime caused by material blockage, and ensure the continuous and stable operation of the production process. The wheel mechanism and the eccentric vibration mechanism work together to enable the equipment to transmit vibration energy to the material evenly and stably. The disc cam mechanism consists of a connecting shaft, a T-plate, a slide groove, a sliding rod, a rotating shaft, a cam ring, a connecting rod, and a circular block. Driven by the rotating shaft, the cam ring precisely controls the movement of the eccentric adjustment plate through components such as the sliding rod and the connecting rod, thereby achieving precise adjustment of the vibration frequency and amplitude of the material. This ensures that the material is fed evenly and continuously during the conveying process, meeting the stringent requirements of high-precision production processes for the stability and continuity of material conveying, and effectively improving product quality.

[0012] (2) The drive mechanism consists of a cavity, through hole, mounting plate, two pairs of damping media, first buffer spring, placement plate, mounting platform, vibration motor, first rotating ring, pulley, and second rotating ring. The damping media on the mounting plate, the first buffer spring, and the second buffer spring in the eccentric vibration mechanism can effectively absorb and buffer the vibration energy during equipment operation, reducing the vibration and noise of the equipment itself. This not only reduces the impact of equipment operation on the surrounding environment and creates a more comfortable working environment for operators, but also reduces equipment wear caused by vibration and extends the service life of the equipment. Furthermore, the vibration motor, pulley, and other parts in the drive mechanism, in conjunction with the disc cam mechanism, The coordinated operation of the eccentric vibration mechanism and the main body of this equipment enables efficient material conveying with less energy consumption compared to traditional vibrating feeders. This reduces the load on components such as motors, lowers energy costs and equipment maintenance costs. The main body adopts a modular design, consisting of a feeding box and a vibrating box connected by a fixing plate and two pairs of hexagonal bolts. Hook seats are fixedly connected to both the left and right sides of the feeding box and the vibrating box. Several mounting blocks are fixedly connected to one side of the feeding box. Each component is independent and easy to disassemble and assemble, making the equipment more convenient for maintenance and repair. Faulty parts can be quickly located and replaced. At the same time, it is also easy to upgrade and modify the equipment according to production needs, improving the equipment's versatility and adaptability. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of an anti-clogging vibratory feeder structure according to an embodiment of the present invention;

[0014] Figure 2 This is a schematic diagram of the drive mechanism structure according to an embodiment of the present invention;

[0015] Figure 3 This is a schematic diagram of the drive mechanism portion of an embodiment of the present invention;

[0016] Figure 4 This is a schematic diagram of the partial structure of the disc cam mechanism and the eccentric vibration mechanism in an embodiment of the present invention;

[0017] Figure 5 This is a schematic diagram of the overall structure of the disc cam mechanism and the eccentric vibration mechanism in an embodiment of the present invention.

[0018] In the diagram: 1. Main unit; 101. Feed box; 102. Vibration box; 103. Fixing plate; 104. Hex bolt; 105. Tension screen; 106. Hook seat; 107. Mounting block; 2. Cavity; 201. Through hole; 202. Mounting plate; 203. Damping medium; 204. First buffer spring; 205. Placement plate; 206. Mounting platform; 207. Vibration motor; 208. First rotating ring; 209. Pulley; 2010. Second rotating ring; 3. Disc cam mechanism; 301, connecting shaft; 302, T-shaped plate; 303, slide groove; 304, sliding rod; 305, rotating shaft; 306, cam ring; 307, connecting rod; 308, circular block; 4. Eccentric vibration mechanism; 401, moving rod; 402, pressing plate; 403, first return spring; 404, mounting bracket; 405, eccentric adjusting plate; 406, second return spring; 407, third return spring; 408, fixed platform; 409, second buffer spring. Detailed Implementation

[0019] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0020] Example 1:

[0021] Please see Figure 1-5As shown, this embodiment proposes an anti-clogging vibrating feeder, which includes a main unit 1. The main unit 1 includes a feeding box 101 and a vibrating box 102 on one side of the feeding box 101. The feeding box 101 and the vibrating box 102 are fixedly connected to each other by a fixing plate 103. Two pairs of hexagonal bolts 104 are fixedly connected to one side of the fixing plate 103. A tension screen 105 is provided inside the feeding box 101. Hook seats 106 are fixedly connected to both the left and right sides of the feeding box 101 and the vibrating box 102. Several mounting blocks 107 are fixedly connected to one side of the feeding box 101. A drive mechanism is provided inside the vibrating box 102. A disc cam mechanism 3 is provided inside the feeding box 101. An eccentric vibration mechanism 4 is provided on one side of the disc cam mechanism 3. The feeding box 101 and the vibrating box 102 constitute the main spatial structure of the main unit 1. The two are firmly connected by the fixing plate 103 and two pairs of hexagonal bolts 104, which improves the operation of the equipment. The equipment provides a solid and reliable support foundation and can effectively resist the impact force generated by vibration during operation, preventing loosening and displacement of various components due to vibration, ensuring the stability of the overall structure of the equipment, reducing the risk of failure caused by structural instability, and extending the service life of the equipment. Secondly, the tension screen 105 installed inside the feeding box 101 is an important component for achieving efficient anti-clogging. During the material conveying process, the tension screen 105 can perform preliminary screening of the material entering the feeding box 101. With its unique screening principle, it intercepts and separates large particles and agglomerated materials, preventing these materials from entering the conveying channel and causing blockage. The hook seats 106 that are fixedly connected to the left and right sides of the feeding box 101 and the vibrating box 102 greatly enhance the flexibility and convenience of equipment installation. The hook seats 106 can be adapted to various installation methods. Whether it is a hanging installation to save ground space or a seat installation to meet specific process layout requirements, it can be easily achieved.

[0022] Preferably, the driving mechanism includes a cavity 2, which is located on the side opposite to the tension screen 105 and is connected to the vibrating box 102. Through holes 201 are provided on both the left and right sides of the vibrating box 102. A mounting plate 202 is fixedly connected inside the vibrating box 102. Two pairs of damping media 203 are fixedly connected to the upper surface of the mounting plate 202. A first buffer spring 204 is movably connected to the upper surface of the damping media 203. A placement plate 205 is fixedly connected to the output end of the upper surface of the first buffer spring 204. Mounting platforms 206 are fixedly connected to the left and right sides of the placement plate 205. A vibration motor 207 is fixedly connected inside the 06. A first rotating ring 208 is rotatably connected to the left and right sides of the vibration motor 207. A pulley 209 is rotatably connected to the outer wall of the first rotating ring 208. A second rotating ring 2010 is rotatably connected inside the pulley 209. The cavity 2 is connected to the vibration box 102 and positioned away from the tension screen 105. This layout not only makes reasonable use of the internal space of the equipment but also provides an independent operating environment for the drive mechanism. It effectively avoids the interference of vibration and heat generated during the operation of the drive mechanism on the tension screen 105 and other components, ensuring the independent stability of each mechanism. For stable operation, the through holes 201 on both sides of the vibratory box 102 facilitate the installation and maintenance of transmission components such as the pulley 209, and also promote air circulation inside the equipment, helping to dissipate the heat generated by components such as the vibration motor 207, preventing overheating and performance degradation, and extending the service life of the equipment. The mounting plate 202 provides a stable mounting base for the damping medium 203 and the first buffer spring 204. The damping medium 203 absorbs the high-frequency vibration energy generated by the vibration motor 207, while the first buffer spring 204 further buffers low-frequency vibrations; the two work synergistically. The function is to significantly reduce the vibration intensity transmitted from the vibration motor 207 to the main body of the equipment. The placement plate 205, supported by the first buffer spring 204, provides a stable mounting surface for the vibration motor 207. The mounting platform 206 precisely positions and firmly fixes the vibration motor 207 to ensure that the vibration motor 207 will not shift during operation. Secondly, the vibration motor 207 drives the pulley 209 to rotate through the first rotating ring 208. The pulley 209 then precisely transmits the power to the rotating shaft 305 through the second rotating ring 2010, thereby driving the cam ring 306 to rotate.

[0023] Preferably, the disc cam mechanism 3 includes a connecting shaft 301, which is positioned on the left and right sides of the inner wall of the feed box 101. A T-shaped plate 302 is fixedly connected to one side of the pair of connecting shafts 301. Sliding grooves 303 are provided on the upper and lower sides of the T-shaped plate 302. Sliding rods 304 are slidably connected inside the pair of sliding grooves 303. A rotating shaft 305 is rotatably connected to the inner wall of the feed box 101, and the rotating shaft 305 passes through the interior of the second rotating ring 2010. A cam ring 306 is rotatably connected to the outer wall of the rotating shaft 305. A connecting rod 307 is fixedly connected to one side of the pair of sliding rods 304. A connecting rod 307 is fixedly connected to one side of the connecting rod 307. A circular block 308 is attached, and by fixing a pair of connecting shafts 301 to the T-shaped plate 302, it is ensured that the T-shaped plate 302 remains stable during the operation of the equipment and will not be displaced or shaken due to vibration or other factors. Secondly, the sliding rod 304 can slide smoothly in the slide groove 303. Driven by the cam ring 306, it can reciprocate along a predetermined trajectory. By adjusting the initial position of the sliding rod 304 in the slide groove 303, its stroke can be changed, thereby adjusting the vibration amplitude of the eccentric vibration mechanism 4. Secondly, the rotating shaft 305 rotates under the drive of the drive mechanism, thereby driving the cam ring 306 connected to the outer wall to rotate synchronously.

[0024] Preferably, the eccentric vibration mechanism 4 includes a movable rod 401, which is fixedly connected to one side of the sliding rod 304. A pressing plate 402 is fixedly connected to one side of the movable rod 401. A pair of first return springs 403 are movably connected to one side of the pressing plate 402. A mounting bracket 404 is fixedly connected to the output end of one side of the first return springs 403. An eccentric adjustment plate 405 is provided inside the mounting bracket 404. Second return springs 406 are movably connected to the upper and lower sides of the eccentric adjustment plate 405, and the second return springs 406 are connected to the inner wall of the mounting bracket 404. A pair of third return springs 407 are movably connected to one side of the mounting bracket 404. A fixed platform 408 is fixedly connected to one output end of spring 407. A pair of second buffer springs 409 are movably connected to the upper surface of the fixed platform 408, and the second buffer springs 409 are connected to the tension screen 105. When the sliding rod 304 reciprocates under the drive of the cam ring 306, the moving rod 401 moves synchronously, driving the extrusion plate 402 to apply force to the first return spring 403. This allows the eccentric vibration mechanism 4 to respond in real time to the motion changes of the disc cam mechanism 3, ensuring the timeliness and accuracy of vibration, and providing continuous and stable vibration power for material conveying. Moreover, the extrusion plate 402, driven by the moving rod 401, extrudes the first return spring 403, and the first return spring 403... After being compressed, the spring 403 releases its elastic potential energy, causing the mounting frame 404 and the internal eccentric adjustment plate 405 to vibrate. Under the constraint of the second return spring 406 and the third return spring 407, the eccentric adjustment plate 405 can perform eccentric movement within a certain range. By changing the eccentricity of the eccentric adjustment plate 405, the frequency and amplitude of the vibration can be precisely adjusted, thereby achieving precise control of the material vibration state. Furthermore, the second return spring 406 and the third return spring 407 respectively constrain and reset the eccentric adjustment plate 405 in the vertical and horizontal directions, ensuring the stability and regularity of the eccentric adjustment plate 405's movement. When the eccentric adjustment plate 405 is subjected to external force... After the action deviates, these two sets of return springs can quickly pull it back to its original position to avoid vibration and disorder. The second buffer spring 409 connects the fixed platform 408 and the tension screen 105, which can effectively buffer the vibration energy transmitted from the eccentric vibration mechanism 4 to the tension screen 105, avoid damage to the tension screen 105 due to excessive vibration, and extend the service life of the tension screen 105. At the same time, through the elastic action of the second buffer spring 409, the tension screen 105 and the eccentric vibration mechanism 4 can form a coordinated vibration, which enhances the screening and anti-blocking effect of materials, ensures that the materials can smoothly enter the subsequent conveying stage after being screened by the tension screen 105, and improves the operating efficiency of the entire feeding system.

[0025] In use, when the anti-blocking vibrating feeder starts working, the operator starts the vibration motor 207. The vibration motor 207 is fixed in the mounting platforms 206 on both sides of the placement plate 205. The placement plate 205 is set on the mounting plate 202 by the first buffer spring 204 and the damping medium 203. The damping medium 203 and the first buffer spring 204 can play a role in buffering and shock absorption, reducing the impact of the vibration motor 207 on the vibrating box 102 and the entire equipment during operation. Moreover, after the vibration motor 207 starts running, it drives the first rotating ring 208 on its left and right sides to rotate. The first rotating ring 208 is rotatably connected to the outer wall of the pulley 209, thereby driving the pulley 209 to rotate. The second rotating ring 208 is rotatably connected inside the pulley 209. 10 also rotates. The second rotating ring 2010 is connected to the rotating shaft 305, thus transmitting the power of the vibration motor 207 to the rotating shaft 305. The rotating shaft 305 passes through the inner wall of the feeding box 101 and its outer wall is rotatably connected to the cam ring 306. When the rotating shaft 305 rotates, the cam ring 306 rotates accordingly. In the disc cam mechanism 3, the connecting shaft 301 is fixed on the left and right sides of the inner wall of the feeding box 101. The T-shaped plate 302 on one side of the connecting shaft 301 remains stable. The sliding rods 304 are slidably connected in the sliding grooves 303 on the upper and lower sides of the T-shaped plate 302. During the rotation of the cam ring 306, its special contour will push the sliding rods 304 to make reciprocating linear motion in the sliding grooves 303. A pair of sliding rods 304 are connected by the connecting rod 307 and the circular block. The connection at 308 ensures the synchronicity of their movements. Secondly, the moving rod 401 of the eccentric vibration mechanism 4 is fixed to one side of the sliding rod 304. Therefore, the reciprocating motion of the sliding rod 304 drives the moving rod 401 to move synchronously. The pressing plate 402 on one side of the moving rod 401 presses the first return spring 403. After being compressed, the first return spring 403 releases its elastic potential energy, pushing the mounting frame 404 and the internal eccentric adjustment plate 405 to vibrate. The eccentric adjustment plate 405 is inside the mounting frame 404, and the second return springs 406 on its upper and lower sides and the third return spring 407 on one side play a restraining and resetting role, ensuring the stability and regularity of the movement of the eccentric adjustment plate 405. By changing the eccentricity of the eccentric adjustment plate 405, the vibration can be precisely adjusted. The frequency and amplitude of the vibration are controlled by the eccentric vibration mechanism 4. The mounting frame 404 is connected to the fixed platform 408 via the third return spring 407. The second buffer spring 409 on the upper surface of the fixed platform 408 is connected to the tension screen 105. The vibration generated by the eccentric vibration mechanism 4 is transmitted to the tension screen 105 through the second buffer spring 409, causing the tension screen 105 to vibrate as well. After the material enters the feed box 101, it first passes through the tension screen 105. The tension screen 105 vibrates under the drive of the eccentric vibration mechanism 4, which can perform preliminary screening of the material, intercepting and separating large particles or lumps of material to prevent them from entering the subsequent conveying channel and causing blockage. At the same time, the vibration generated by the eccentric vibration mechanism 4 is transmitted to the material in the entire feed box 101, causing the material to produce appropriate sliding or throwing motion in the tank.To prevent materials from piling up and sticking together inside the container, ensuring that materials are conveyed downwards evenly and continuously, thus achieving the functions of anti-blocking and stable feeding.

[0026] The preferred embodiments of this utility model disclosed above are merely illustrative of the present utility model. These preferred embodiments do not exhaustively describe all details, nor do they limit the utility model to any specific implementation. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of this utility model, thereby enabling those skilled in the art to better understand and utilize it. This utility model is limited only by the claims and their full scope and equivalents.

Claims

1. An anti-clogging vibrating feeder, the anti-clogging vibrating feeder comprising: The main unit (1) includes a feeding box (101) and a vibrating box (102) on one side of the feeding box (101). The feeding box (101) and the vibrating box (102) are fixedly connected to each other by a fixing plate (103). Two pairs of hexagonal bolts (104) are fixedly connected to one side of the fixing plate (103). A tension screen (105) is provided inside the feeding box (101). Hook seats (106) are fixedly connected to both the left and right sides of the feeding box (101) and the vibrating box (102). Several mounting blocks (107) are fixedly connected to one side of the feeding box (101). The main unit (1) is characterized in that a driving mechanism is provided inside the vibrating box (102), a disc cam mechanism (3) is provided inside the feeding box (101), and an eccentric vibration mechanism (4) is provided on one side of the disc cam mechanism (3).

2. The anti-clogging vibrating feeder according to claim 1, characterized in that: The driving mechanism includes a cavity (2), which is located on the side opposite to the tension screen (105) and connected to the vibrating box (102). The vibrating box (102) has through holes (201) on both its left and right sides. An installation plate (202) is fixedly connected inside the vibrating box (102). Two pairs of damping media (203) are fixedly connected to the upper surface of the installation plate (202). A first buffer spring (204) is movably connected to the upper surface of each damping media (203). A placement plate (205) is fixedly connected to the output end of the upper surface of the spring (204). A mounting platform (206) is fixedly connected to the left and right sides of the placement plate (205). A vibration motor (207) is fixedly connected inside the mounting platform (206). A first rotating ring (208) is rotatably connected to the left and right sides of the vibration motor (207). A pulley (209) is rotatably connected to the outer wall of the first rotating ring (208). A second rotating ring (2010) is rotatably connected inside the pulley (209).

3. The anti-clogging vibrating feeder according to claim 2, characterized in that: The disc cam mechanism (3) includes a connecting shaft (301), which is located on the left and right sides of the inner wall of the feed box (101). A T-shaped plate (302) is fixedly connected to one side of the pair of connecting shafts (301). Slide grooves (303) are provided on the upper and lower sides of the T-shaped plate (302). Slide rods (304) are slidably connected inside the pair of slide grooves (303). A rotating shaft (305) is rotatably connected to the inner wall of the feed box (101), and the rotating shaft (305) passes through the interior of the second rotating ring (2010). A cam ring (306) is rotatably connected to the outer wall of the rotating shaft (305). A connecting rod (307) is fixedly connected to one side of the pair of slide rods (304), and a circular block (308) is fixedly connected to one side of the connecting rod (307).

4. The anti-clogging vibrating feeder according to claim 3, characterized in that: The eccentric vibration mechanism (4) includes a moving rod (401), which is fixedly connected to one side of a sliding rod (304). A pressing plate (402) is fixedly connected to one side of the moving rod (401), and a pair of first return springs (403) are movably connected to one side of the pressing plate (402). A mounting bracket (404) is fixedly connected to the output end of one side of the first return springs (403). An eccentric adjustment plate (405) is provided inside the mounting bracket (404). The upper and lower sides of 05) are movably connected with second return springs (406), and the second return springs (406) are connected to the inner wall of the mounting frame (404). A pair of third return springs (407) are movably connected to one side of the mounting frame (404). A fixed platform (408) is fixedly connected to the output end of one side of the pair of third return springs (407). A pair of second buffer springs (409) are movably connected to the upper surface of the fixed platform (408), and the second buffer springs (409) are connected to the tension screen (105).

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