Bus passenger door lower crossbeam welding positioning tool

Abstract

This invention relates to the field of crossbeam welding positioning technology, and discloses a welding positioning fixture for the lower crossbeam of a passenger door in a bus. The fixture includes a base plate and two fixing parts, both positioned above the base plate; a synchronous drive unit mounted on the base plate; and a rotating part mounted on the base plate. Each fixing part includes a drive assembly mounted on the base plate; and a fixing component mounted on the drive assembly. The drive assembly includes a small support frame mounted on the top of the base plate, through which a hollow shaft passes. This invention, by incorporating fixing parts, solves the problem that existing positioning fixtures often fail to achieve multi-directional synchronous positioning and clamping during use, resulting in insufficiently tight and stable positioning and causing workpiece displacement and wobbling during welding, thus affecting welding stability.

Description

Technical Field

[0001] This invention relates to the field of crossbeam welding and positioning technology, specifically to a welding and positioning fixture for the crossbeam under the passenger door of a bus. Background Technology

[0002] With the rapid upgrading of the bus manufacturing industry, the requirements for welding precision and assembly stability of the vehicle body structure are constantly increasing. As a key load-bearing connecting component of the bus body, the welding quality of the passenger door lower crossbeam directly determines the overall strength and safety of the bus body. Therefore, a special welding positioning fixture for the passenger door lower crossbeam is needed to position, clamp and weld the workpiece.

[0003] However, existing positioning fixtures are difficult to use to achieve multi-directional synchronous positioning and clamping, resulting in insufficient tightness and stability of the positioning fit. This causes the workpiece to easily shift or shake during the welding process, thus affecting the stability of the welding. Summary of the Invention

[0004] The purpose of this invention is to provide a welding positioning fixture for the lower crossbeam of a passenger door in a bus. By setting a fixing part, it solves the problem that existing positioning fixtures are difficult to achieve multi-directional synchronous positioning and clamping during use, resulting in insufficient tight and stable positioning and fitting, causing the workpiece to easily shift and shake during the welding process, thus affecting the welding stability.

[0005] To solve the above-mentioned technical problems, the present invention is achieved through the following technical solution: This invention relates to a welding and positioning fixture for the lower crossbeam of a passenger door in a bus, comprising a base plate and: two fixing parts, both positioned above the base plate; a synchronous drive part mounted on the base plate; and a rotating part disposed on the base plate. Each fixing part includes a drive assembly disposed on the base plate; a fixing component is mounted on the drive assembly; the drive assembly includes a small support frame disposed on the top of the base plate, through which a hollow shaft passes, rotatably connected to the small support frame, and a drive rod fixedly connected to the outer wall of the hollow shaft. Two limiting grooves are provided on the small support frame. Each of the two inner supports is slidably connected to a slider. Each slider is hinged with a transmission rod, which is hinged to a drive rod. A fixed frame is fixedly connected to the side of the small support frame away from the drive rod. A cylindrical rod slides through the fixed frame. A drive component and an elastic component are mounted on the cylindrical rod. The cylindrical rod is located inside and in contact with the hollow shaft. The drive component includes a spiral groove formed on the outer wall of the cylindrical rod, within which a transmission block is mounted. The transmission block is fixedly connected to the hollow shaft. The elastic component includes a spring sleeved on the outer wall of the cylindrical rod. The side of the spring closest to the L-shaped placement plate is fixedly connected to the L-shaped placement plate, and the side of the spring away from the L-shaped placement plate is fixedly connected to the fixed frame.

[0006] Furthermore, the synchronous drive unit includes a limiting component mounted on the base plate and a power component disposed on the limiting component.

[0007] Furthermore, the rotating part includes trapezoidal support plates respectively disposed on opposite sides of two small support frames. A rotating shaft passes through each of the two trapezoidal support plates, and the two rotating shafts are rotatably connected to the two trapezoidal support plates respectively. The sides of the two rotating shafts that are close to each other are fixedly connected to a connecting plate. The sides of the two connecting plates that are close to each other are fixedly connected to the two small support frames respectively. A second motor is fixedly connected to the left side of the trapezoidal support plate located on the left side. The output shaft of the second motor is fixedly connected to the rotating shaft located on the left side via a coupling. The two trapezoidal support plates are mirror images of each other.

[0008] Furthermore, the fixing assembly includes an L-shaped placement plate fixedly connected to the side of the cylindrical rod away from the fixing frame. An anti-slip buffer pad is fixedly connected to the L-shaped placement plate. A fixing plate is fixedly connected to the side of each of the two sliders away from the two transmission rods. An anti-slip buffer pad is fixedly connected to the side of each of the two fixing plates that is close to each other. The two fixing plates are located on the front and rear sides of the L-shaped placement plate, respectively.

[0009] Furthermore, the limiting component includes a large support frame fixedly connected to the top of the base plate. The top of the large support frame is provided with a limiting groove II. Two movable plates are slidably connected in the limiting groove II. The tops of the two movable plates are respectively fixedly connected to two trapezoidal support plates. The two movable plates are mirror images of each other.

[0010] Furthermore, the power assembly includes two rectangular plates fixedly connected to the inner wall of the top of the large support frame. A bidirectional threaded rod is rotatably connected between the two rectangular plates. The right side of the bidirectional threaded rod passes through the rectangular plate on the right side. A motor is fixedly connected to the right side of the rectangular plate on the right side. The output shaft of the motor is fixedly connected to the bidirectional threaded rod via a coupling. A protective component is provided on the bidirectional threaded rod. The bidirectional threaded rod is arranged parallel to the limiting slide groove. The bidirectional threaded rod passes through two movable plates. Both movable plates are threadedly connected to the bidirectional threaded rod. The protective component includes several telescopic anti-slip covers sleeved on the outer wall of the bidirectional threaded rod. The two telescopic anti-slip covers on the left and right sides, with their opposite sides fixedly connected to the two rectangular plates, and the two telescopic anti-slip covers on the left and right sides, with their opposite sides fixedly connected to the two movable plates. Three telescopic anti-slip covers are provided, and the two sides of the telescopic anti-slip cover in the middle are fixedly connected to the two movable plates.

[0011] The present invention has the following beneficial effects: (1) By setting a fixed part, when the small support frame moves towards each other, the fixed frame and the spring drive the cylindrical rod to move, so that the anti-slip buffer pad 1 is attached to the crossbeam to be welded from the left and right sides; the small support frame continues to move closer and slides along the cylindrical rod and squeezes the spring to store energy. At the same time, the hollow shaft is driven to rotate by the cooperation of the transmission block and the spiral groove, which in turn drives the drive rod and the transmission rod to move in linkage. Under the constraint of the limiting slide groove 1, the slider moves towards each other, and finally drives the fixed plate and the anti-slip buffer pad 2 to clamp the workpiece from the front and rear sides. It cooperates with the anti-slip buffer pad 1 on the left and right sides to complete the all-round positioning and fixing of the crossbeam. Through mechanical linkage, multi-directional synchronous positioning and clamping is achieved, and the workpiece is automatically fixed around the perimeter. The positioning and fitting are tight and stable, which effectively improves the stability of the workpiece during welding. (2) By setting up a synchronous drive unit, the crossbeam to be welded is placed on the L-shaped placement plate during use. The bidirectional threaded rod is driven to rotate by motor one. With the cooperation of the bidirectional threaded rod and the limiting slide groove two, the two moving plates are driven to move towards each other. The telescopic anti-slip cover adapts to the movement of the moving plates and forms protection for the bidirectional threaded rod. The moving plates are then driven by the transmission linkage of the trapezoidal support plate, the small support frame and the cylindrical rod to drive the two L-shaped placement plates to move synchronously towards each other, realize the synchronous centering adjustment of the workpiece placement position, and ensure that the positioning and clamping are regular and reliable, avoiding clamping offset. The telescopic anti-slip cover can effectively protect the bidirectional threaded rod and reduce the corrosion of dust and welding slag. (3) By setting up a rotating part, when it is necessary to switch the welding surface of the crossbeam, the second motor starts and drives the connecting plate to rotate through the rotating shaft. The connecting plate then drives the small support frame and the crossbeam that has been clamped and fixed to rotate as a whole. While one side drives the rotation, the other side fixation structure works together to make the rotating shaft rotate smoothly on the trapezoidal support plate. The two rotating shafts work together to realize the smooth rotation of the crossbeam to be welded, and complete the angle adjustment of the welding station and the welding surface. The welding surface can be switched without disassembly and re-clamping, which improves the continuity of welding operations and the overall processing efficiency.

[0012] Of course, any product implementing this invention does not necessarily need to achieve all of the advantages described above at the same time. Attached Figure Description

[0013] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0014] Figure 1 This is a schematic diagram of the overall structure of the present invention; Figure 2 This is a partial cross-sectional view of the fixing part of the present invention; Figure 3 This is a partial exploded view of the cylindrical rod of the present invention; Figure 4 This is a partial cross-sectional view of the driving component of the present invention; Figure 5 This is a partial cross-sectional view of the synchronous drive unit of the present invention; Figure 6 This is a partial cross-sectional view of the rotating part of the present invention; Figure 7 For the present invention Figure 6 A magnified structural diagram of A in the diagram.

[0015] The attached diagram lists the components represented by each number as follows: In the diagram: 111, base plate; 2, fixing part; 21, drive assembly; 211, small support frame; 212, hollow shaft; 213, drive rod; 214, limit slide groove one; 215, slider; 216, transmission rod; 217, fixing frame; 218, cylindrical rod; 219, spiral groove; 2110, transmission block; 2111, spring; 22, fixing assembly; 221, L-shaped placement plate; 222, anti-slip buffer pad one; 223. Fixed plate; 224. Anti-slip buffer pad II; 3. Synchronous drive unit; 31. Limiting component; 311. Large support frame; 312. Limiting slide groove II; 313. Moving plate; 32. Power component; 321. Rectangular plate; 322. Bidirectional threaded rod; 323. Motor I; 324. Telescopic anti-slip cover; 4. Rotating part; 411. Trapezoidal support plate; 412. Rotating shaft; 413. Connecting plate; 414. Motor II. Detailed Implementation

[0016] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0017] Please see Figures 1-7 As shown, the present invention is a welding positioning fixture for the lower crossbeam of a passenger door of a bus, including a base plate 111, and further including: a fixing part 2, two fixing parts 2 are provided, both fixing parts 2 are located above the base plate 111; a synchronous drive part 3 is installed on the base plate 111; and a rotating part 4 is installed on the base plate 111.

[0018] The fixing part 2 includes a drive assembly 21, which is mounted on the base plate 111; and a fixing assembly 22, which is mounted on the drive assembly 21. The drive assembly 21 includes a small support frame 211 mounted on the top of the base plate 111. A hollow shaft 212 passes through the small support frame 211 and is rotatably connected to the small support frame 211. A drive rod 213 is fixedly connected to the outer wall of the hollow shaft 212. Two limiting grooves 214 are provided on the small support frame 211. Each of the two limiting grooves 214 contains a... A sliding block 215 is slidably connected, and a transmission rod 216 is hinged to each of the two sliding blocks 215. Both transmission rods 216 are hinged to the drive rod 213. A fixed frame 217 is fixedly connected to the side of the small support frame 211 away from the drive rod 213. A cylindrical rod 218 slides through the fixed frame 217. A drive component and an elastic component are provided on the cylindrical rod 218. The cylindrical rod 218 is located inside and in contact with the hollow shaft 212. The drive component includes a spiral groove 21 formed on the outer wall of the cylindrical rod 218. 9. A transmission block 2110 is provided inside the spiral groove 219. The transmission block 2110 is fixedly connected to the hollow shaft 212. The elastic element includes a spring 2111 sleeved on the outer wall of the cylindrical rod 218. The side of the spring 2111 near the L-shaped placement plate 221 is fixedly connected to the L-shaped placement plate 221, and the side of the spring 2111 away from the L-shaped placement plate 221 is fixedly connected to the fixing frame 217. The fixing assembly 22 includes an L-shaped placement plate 221 fixedly connected to the side of the cylindrical rod 218 away from the fixing frame 217. Anti-slip buffer pad 222 is fixedly connected to the upper part of the L-shaped placement plate 221. Fixing plate 223 is fixedly connected to the side of the two sliders 215 away from the two transmission rods 216. Anti-slip buffer pad 224 is fixedly connected to the side of the two fixing plates 223 that are close to each other. The two fixing plates 223 are located on the front and rear sides of the L-shaped placement plate 221 respectively. By setting the fixing part 2, multi-directional synchronous positioning and clamping is achieved through mechanical linkage, which automatically completes the workpiece's four-dimensional limiting and fixing. The positioning fit is tight and stable, which effectively improves the stability of the workpiece during welding.

[0019] The synchronous drive unit 3 includes a limiting component 31, which is mounted on the base plate 111; and a power component 32, which is mounted on the limiting component 31. The limiting component 31 includes a large support frame 311 fixedly connected to the top of the base plate 111. A second limiting groove 312 is formed on the top of the large support frame 311, and two movable plates 313 are slidably connected within the second limiting groove 312. The tops of the two movable plates 313 are respectively fixedly connected to two trapezoidal support plates 411. The two movable plates 313 are mirror images of each other. The power component 32 includes two rectangular plates 321 fixedly connected to the inner wall of the top of the large support frame 311. A bidirectional threaded rod 322 is rotatably connected between the two rectangular plates 321. The right side of the bidirectional threaded rod 322 passes through the right rectangular plate 321. A motor 323 is fixedly connected to the right side of the right rectangular plate 321. The output shaft of the motor 323 is fixedly connected to the bidirectional threaded rod 322 via a coupling. A protective component is provided on the rod 322; the bidirectional threaded rod 322 is arranged parallel to the limiting slide groove 312, and the bidirectional threaded rod 322 passes through two moving plates 313. Both moving plates 313 are threadedly connected to the bidirectional threaded rod 322. The protective component includes several telescopic anti-slip covers 324 sleeved on the outer wall of the bidirectional threaded rod 322. The two telescopic anti-slip covers 324 located on the left and right sides are fixedly connected to two rectangular plates 321 on their respective far sides, and the two telescopic anti-slip covers 324 located on the left and right sides are fixedly connected to two moving plates 313 on their respective close sides. Three telescopic anti-slip covers 324 are provided, and the two sides of the telescopic anti-slip cover 324 located in the middle are fixedly connected to two moving plates 313 on their respective sides. By setting up a synchronous drive unit 3, the synchronous centering adjustment of the workpiece placement station is realized, the positioning and clamping are regular and reliable, and clamping deviation is avoided. The telescopic anti-slip covers 324 can effectively protect the bidirectional threaded rod 322 and reduce the corrosion of dust and welding slag.

[0020] The rotating part 4 includes trapezoidal support plates 411 respectively disposed on opposite sides of two small support frames 211. A rotating shaft 412 passes through each trapezoidal support plate 411, and the two rotating shafts 412 are rotatably connected to the two trapezoidal support plates 411 respectively. The sides of the two rotating shafts 412 that are close to each other are fixedly connected to a connecting plate 413. The sides of the two connecting plates 413 that are close to each other are fixedly connected to the two small support frames 211 respectively. A second motor 414 is fixedly connected to the left side of the trapezoidal support plate 411 located on the left. The output shaft of the second motor 414 is fixedly connected to the rotating shaft 412 located on the left side via a coupling. The two trapezoidal support plates 411 are mirror images of each other. By setting up the rotating part 4, the welding surface can be switched without disassembly and re-clamping, improving the continuity of welding operations and overall processing efficiency.

[0021] It should be noted that both motor 323 and motor 414 in this application can be automatically controlled by inputting relevant parameters according to the program set in the control panel. The setting of this control method can be achieved by existing technology, such as PLC.

[0022] In use, the beam to be welded is placed on two L-shaped placement plates 221, and the motor 323 is started. The motor 323 drives the bidirectional threaded rod 322 to rotate. Under the action of the bidirectional threaded rod 322 and the limiting slide groove 312, the two moving plates 313 are driven to move closer to each other. The three telescopic anti-slip covers 324 deform as the two moving plates 313 move and protect the bidirectional threaded rod 322. The two moving plates 313 respectively drive the two trapezoidal support plates 411 to move closer to each other. The two trapezoidal support plates 411 respectively drive the two L-shaped placement plates 221 to move closer synchronously through the cylindrical rods 218 on the two small support frames 211. As the two small support frames 211 approach each other, the small support frames 211 drive the cylindrical rod 218 to move via the fixed frame 217 and the spring 2111. The cylindrical rod 218, via the L-shaped placement plate 221, drives the anti-slip buffer pad 222 to contact the left and right sides of the crossbeam to be welded. Then, the two small support frames 211 continue to approach each other. At this time, the small support frames 211 drive the hollow shaft 212 and the fixed frame 217 to slide on the cylindrical rod 218, compressing the spring 2111, causing the spring 2111 to deform and generate elastic force. Under the action of the transmission block 2110 and the spiral groove 219, the hollow shaft 212 rotates on the small support frame 211, driving the... When the drive rod 213 rotates, since both transmission rods 216 are hinged to the drive rod 213 and both transmission rods 216 are hinged to the two sliders 215 respectively, the drive rod 213 drives the two sliders 215 to move through the two transmission rods 216. Under the limiting action of the two limiting grooves 214, the two sliders 215 are brought closer to each other. The two sliders 215 respectively drive the two fixing plates 223 to move closer to each other. The two fixing plates 223 drive the two anti-slip buffer pads 224 to move closer to each other and fix the front and rear sides of the crossbeam to be welded. They also cooperate with the left and right sides of the anti-slip buffer pads 222 on the two L-shaped placement plates 221 to fix the crossbeam to be welded. The beam to be welded is then welded using a welding device. When it is necessary to adjust the welding surface of the crossbeam to be welded, start motor 2 414. Motor 2 414 drives the connecting plate 413 to rotate through the corresponding rotating shaft 412. The connecting plate 413 drives the corresponding small support frame 211 to rotate. The small support frame 211 drives the fixed crossbeam to be welded to rotate. Since one side of the crossbeam to be welded has been welded, the small support frame 211 is driven to rotate through the fixed structure on the other side. The small support frame 211 drives the rotating shaft 412 to rotate on the trapezoidal support plate 411 through the connecting plate 413. With the cooperation of the two rotating shafts 412, the crossbeam to be welded is made to rotate smoothly, thereby adjusting the welding surface of the crossbeam to be welded.

[0023] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. 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 the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A welding and positioning fixture for the lower crossbeam of a passenger door in a bus, comprising a base plate (111), characterized in that, Also includes: Fixing part (2), two fixing parts (2) are provided, and both fixing parts (2) are provided above the base plate (111); Synchronous drive unit (3), which is mounted on base plate (111); Rotating part (4), the rotating part (4) is disposed on the base plate (111); The fixing part (2) includes a driving assembly (21), which is disposed on the base plate (111); as well as A fixing component (22) is disposed on the driving component (21); The drive assembly (21) includes a small support frame (211) disposed on the top of the base plate (111). A hollow shaft (212) passes through the small support frame (211) and is rotatably connected to the small support frame (211). A drive rod (213) is fixedly connected to the outer wall of the hollow shaft (212). Two limiting grooves (214) are provided on the small support frame (211), and each of the two limiting grooves (214) is slidably connected to a drive rod (213). The slider (215) has a transmission rod (216) hinged on each of the two sliders (215). The two transmission rods (216) are hinged to the drive rod (213). The small support frame (211) is fixedly connected to a fixed frame (217) on the side away from the drive rod (213). A cylindrical rod (218) slides through the fixed frame (217). A drive member is provided on the cylindrical rod (218). An elastic member is provided on the cylindrical rod (218). The cylindrical rod (218) is located inside the hollow shaft (212) and is in contact with it.

2. The welding and positioning fixture for the lower crossbeam of a passenger door in a bus according to claim 1, characterized in that, The synchronous drive unit (3) includes a limiting component (31) mounted on a base plate (111); and A power assembly (32) is disposed on a limiting assembly (31).

3. The welding and positioning fixture for the lower crossbeam of a passenger door in a bus according to claim 1, characterized in that, The rotating part (4) includes trapezoidal support plates (411) respectively disposed on the opposite side of two small support frames (211). A rotating shaft (412) passes through each of the two trapezoidal support plates (411). The two rotating shafts (412) are rotatably connected to the two trapezoidal support plates (411). The side of the two rotating shafts (412) that is close to each other is fixedly connected to a connecting plate (413). The side of the two connecting plates (413) that is close to each other is fixedly connected to the two small support frames (211). A second motor (414) is fixedly connected to the left side of the trapezoidal support plate (411) located on the left. The output shaft of the second motor (414) is fixedly connected to the rotating shaft (412) located on the left through a coupling. The two trapezoidal support plates (411) are mirror images of each other.

4. The welding and positioning fixture for the lower crossbeam of a passenger door in a bus according to claim 1, characterized in that, The fixing component (22) includes an L-shaped placement plate (221) fixedly connected to the side of the cylindrical rod (218) away from the fixing frame (217). An anti-slip buffer pad (222) is fixedly connected to the L-shaped placement plate (221). A fixing plate (223) is fixedly connected to the side of the two sliders (215) away from the two transmission rods (216). An anti-slip buffer pad (224) is fixedly connected to the side of the two fixing plates (223) that are close to each other. Among them, the two fixing plates (223) are located on the front and rear sides of the L-shaped placement plate (221), respectively.

5. The welding and positioning fixture for the lower crossbeam of a passenger door in a bus according to claim 2, characterized in that, The limiting component (31) includes a large support frame (311) fixedly connected to the top of the base plate (111). The top of the large support frame (311) is provided with a limiting groove (312). Two movable plates (313) are slidably connected in the limiting groove (312). The tops of the two movable plates (313) are respectively fixedly connected to two trapezoidal support plates (411). The two movable boards (313) are mirror images of each other.

6. The welding and positioning fixture for the lower crossbeam of a passenger door in a bus according to claim 2, characterized in that, The power assembly (32) includes two rectangular plates (321) fixedly connected to the inner wall of the top of the large support frame (311). A bidirectional threaded rod (322) is rotatably connected between the two rectangular plates (321). The right side of the bidirectional threaded rod (322) passes through the rectangular plate (321) on the right side. A motor (323) is fixedly connected to the right side of the rectangular plate (321) on the right side. The output shaft of the motor (323) is fixedly connected to the bidirectional threaded rod (322) through a coupling. A protective component is provided on the bidirectional threaded rod (322). Among them, the bidirectional threaded rod (322) and the limiting slide groove (312) are arranged in parallel. The bidirectional threaded rod (322) passes through the two moving plates (313), and the two moving plates (313) are threadedly connected to the bidirectional threaded rod (322).

7. The welding and positioning fixture for the lower crossbeam of a passenger door in a bus according to claim 1, characterized in that, The driving component includes a spiral groove (219) formed on the outer wall of the cylindrical rod (218), and a transmission block (2110) is provided in the spiral groove (219). The transmission block (2110) is fixedly connected to the hollow shaft (212).

8. The welding and positioning fixture for the lower crossbeam of a passenger door in a bus according to claim 1, characterized in that, The elastic element includes a spring (2111) sleeved on the outer wall of the cylindrical rod (218). The side of the spring (2111) closest to the L-shaped placement plate (221) is fixedly connected to the L-shaped placement plate (221), and the side of the spring (2111) furthest from the L-shaped placement plate (221) is fixedly connected to the fixing frame (217).

9. The welding and positioning fixture for the lower crossbeam of a passenger door in a bus according to claim 6, characterized in that, The protective component includes several telescopic anti-slip covers (324) sleeved on the outer wall of the bidirectional threaded rod (322). The two telescopic anti-slip covers (324) located on the left and right sides are respectively fixedly connected to two rectangular plates (321) on their respective far sides. The two telescopic anti-slip covers (324) located on the left and right sides are respectively fixedly connected to two movable plates (313) on their respective close sides. Among them, there are three telescopic anti-slip covers (324), and the telescopic anti-slip cover (324) located in the middle is fixedly connected to two movable plates (313) on both sides respectively.

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