CN111701841A

CN111701841A - Grit sieving mechanism of oscillating bridge construction usefulness

Info

Publication number: CN111701841A
Application number: CN202010587244.XA
Authority: CN
Inventors: 程效银
Original assignee: Individual
Current assignee: Jianshi Changsheng Aggregate Co ltd
Priority date: 2020-06-24
Filing date: 2020-06-24
Publication date: 2020-09-25
Anticipated expiration: 2040-06-24
Also published as: CN111701841B

Abstract

The invention discloses a gravel screening device for swing type bridge construction, which comprises a support, a top sliding rod, a connecting pipe and a stirring rod, wherein a conveying pipe is fixedly installed on the outer side surface of the support, the top sliding rod is mutually connected with the conveying pipe through a top sliding groove, the inner side of the support is fixedly installed on the side sliding rod, the inner side of the support is mutually connected with a vibrating plate through a vibrating spring, the connecting pipe is fixedly installed at the middle position of the lower end of the conveying pipe, an inner sliding groove is reserved inside the conveying pipe, the outer side of a limiting block is mutually connected with the conveying rod through a telescopic rod, a screen is fixedly installed inside the lower surface of a screening frame, and the outer part of the pushing. This grit sieving mechanism of oscillating bridge construction usefulness adopts neotype structural design for this device is convenient for carry out categorised unloading of going up to the grit through mechanical transmission mechanism, uses comparatively laborsavingly, and is provided with in the device and prevents blockking up the mechanism, keeps the smoothness nature of processing.

Description

Grit sieving mechanism of oscillating bridge construction usefulness

Technical Field

The invention relates to the technical field of bridge construction, in particular to a sand and stone screening device for swing type bridge construction.

Background

The bridge construction technology precision and the bearing performance requirement are high, the requirement on materials in the construction process is higher than that of common vertical face construction, certain requirements on quality and purity are met by some basic materials such as sand stones and cement, more massive stone structures are doped in part of the sand stones, the purity is low, the requirements on road and bridge construction materials are not met, and the sand stones need to be screened before the materials are mixed and processed, so that the purity of the sand stones is improved.

Along with the continuous processing use of grit sieving mechanism, found following problem in the use:

1. the grit material that needs in the bridge work progress is more, and the work load of screening processing is great, and the unloading of independently classifying is not convenient for carry on at the in-process of processing to current partial sieving mechanism, around the processing, needs artifical material loading or the prediction in the clearance sieving mechanism, uses comparatively difficultly.

2. On the other hand grit structure is less, inside the easy blocking device of in-process of continuous processing, and the grit is simultaneously concentrated when the ejection of compact screening and is stacked in the side of screen cloth, blocks up the mesh easily, influences going on of screening processing.

Therefore, the sand screening device for the swing type bridge construction needs to be designed aiming at the problems.

Disclosure of Invention

The invention aims to provide a gravel screening device for swing type bridge construction, and aims to solve the problems that more gravel materials are needed in the bridge construction process, the workload of screening and processing is large, the existing screening device is inconvenient to independently classify and feed and discharge in the processing process, manual feeding or prediction in the screening device is needed before and after processing, the use is labor-consuming, the gravel structure is small, the interior of the device is easily blocked in the continuous processing process, and meanwhile, gravel is intensively stacked on the side surface of a screen during discharging and screening, so that meshes are easily blocked, and the screening and processing are affected in the background technology.

In order to achieve the purpose, the invention provides the following technical scheme: a gravel screening device for swing type bridge construction comprises a support, side sliding rods, a connecting pipe and a stirring rod, wherein a conveying pipe is fixedly installed on the outer side face of the support, a side conveying shaft is rotatably connected to the inside of the left side of the conveying pipe, a middle conveying shaft is rotatably installed at the middle position of the inside of the conveying pipe, a disc is welded on the upper surfaces of the side conveying shaft and the middle conveying shaft, a push rod is movably installed on the inner side of the disc, a top sliding rod is fixedly installed on the lower surface of the push rod and is connected with the conveying pipe through a top sliding groove, the top sliding groove is formed in the upper surface of the conveying pipe, a transmission disc is rotatably installed on the upper surface of the conveying pipe, a fixing ring is welded on the outer side of the upper end of the conveying pipe, the side sliding rods are fixedly installed on, the side chutes are symmetrically arranged at two sides of the outer part of the screening frame, the inner side of the bracket is connected with the vibrating plate through a vibrating spring, the connecting pipe is fixedly arranged at the middle position of the lower end of the conveying pipe, the outer part of the connecting pipe is welded with the fixing plate, the fixing plate is connected with the screening frame through the transmission rod, the inner part of the transmission rod is reserved with the inner chute, the inner chute is movably connected with a middle rotating shaft, the stirring rods are symmetrically fixed at two sides of the outer part of the connecting pipe, the middle chute is arranged at the inner side of the side surface of the stirring rod, the middle chute is movably connected with a limiting block, the outer side of the limiting block is connected with the transmission rod through a telescopic rod, the inner side of the limiting block is connected with the dredging plate through a built-in rod, and an external gear is welded in the middle of the outer side of the rotary drum, and a side gear is movably mounted on the side surface of the external gear.

Preferably, the push rod is rotatably connected with the disc, and the push rod and the conveying pipe form a sliding structure through the top sliding rod and the top sliding groove.

Preferably, the inner side of the transmission disc is movably connected with an adjusting block, a threaded rod is movably arranged inside the left side of the adjusting block, and the threaded rod is in threaded connection with the transmission disc, the rotary drum and the push rod.

Preferably, the screening frame forms a sliding structure through a side sliding chute and a side sliding rod, the side sliding chute is of an arc-shaped structure, and the screening frame forms a rotating structure through a transmission rod and a fixing plate.

Preferably, the screening frame and the conveying pipe form a mutual communication structure through the connecting pipe, the inner lower surface of the upper end of the conveying pipe is of an inclined structure, and the height of the lower surface of the inner left side of the conveying pipe is lower than the height of the lower surface of the inner right side of the conveying pipe.

Preferably, the vibration plate and the bracket form an elastic structure through the vibration spring, and the position of the vibration plate corresponds to the position of the fixing ring.

Preferably, the middle rotating shaft and the transmission rod form a sliding structure through the inner sliding groove, the middle rotating shaft is of a Z-shaped structure, and the transmission rod and the limiting block form a telescopic structure through the telescopic rod.

Preferably, the limiting block and the stirring rod form a sliding structure through a middle sliding groove, and the inner side and the outer side of the limiting block are fixedly connected with the telescopic rod and the built-in rod respectively.

Preferably, the dredging plate and the stirring rod form a telescopic structure through a built-in rod, 2 dredging plates are symmetrically arranged around the center of the screening frame, and the dredging plates are connected with the screen in a clamping manner.

Compared with the prior art, the invention has the beneficial effects that: the gravel screening device for the swing type bridge construction adopts a novel structural design, so that the device can conveniently and rapidly carry out classified loading and unloading, labor is saved, and an anti-blocking structure is arranged in the device, so that the normal operation of gravel screening is kept;

1. the side transmission shaft and the middle transmission shaft arranged on the rotating structure, and the push rod and the threaded rod arranged on the transmission structure, when feeding, the side conveying shaft is arranged in a sandstone structure to be processed, the threaded rod is controlled by the operation motor to be rotatably installed on the inner side of the adjusting block, the operation motor simultaneously controls the side conveying shaft and the middle conveying shaft to rotate through the transmission structure, the sandstone raw materials on the outer side are conveyed into the device by the side conveying shaft, the sandstone raw materials are conveyed into the screening frame by the middle conveying shaft, the screening frame screens the sandstone when swinging back and forth, the processing is finished, the control threaded rod is separated from the adjusting block, the middle conveying shaft is controlled by the operation motor to rotate reversely, residues in the screening frame are conveyed to the right side of the conveying pipe to be led out, the structure can sort and screen the sandstone materials through a mechanical structure, so that the labor is saved, and the use is convenient and fast;

2. the stopper that sliding structure set up, and the vibrations board that elastic structure set up, when screening frame reciprocating swing screening grit, discontinuity promotes the vibrations board and reciprocates, the solid fixed ring of vibrations board reciprocating impact, the conveyer pipe to solid fixed ring inside part produces vibrations influence, avoid the grit material to a certain extent inside the in-process blocking device of feeding, the transfer line is when promoting screening frame reciprocating swing simultaneously, under the effect of telescopic link and stopper, promote the flexible removal in the side of puddler of mediation board, the inside that the intermittent type block got into the screen cloth between the mediation board, dredge the grit structure of jam in the screen cloth inside, avoid the grit jam inside the mesh of screen cloth, keep grit screening process normal clear in succession.

Drawings

FIG. 1 is a schematic cross-sectional front view of the present invention;

FIG. 2 is a schematic front view of the connecting tube of the present invention;

FIG. 3 is a schematic structural view of a sieving frame in front cross section according to the present invention;

FIG. 4 is a schematic structural diagram of the front surface of the dredging board of the present invention;

FIG. 5 is a schematic side view of the screening frame of the present invention;

FIG. 6 is a front view of the threaded rod of the present invention;

fig. 7 is a schematic sectional view of the push rod of the present invention.

In the figure: 1. a support; 2. a delivery pipe; 3. a lateral transfer shaft; 4. an intermediate transfer shaft; 5. a disc; 6. a push rod; 7. a top slide bar; 8. a top chute; 9. a drive plate; 10. a fixing ring; 11. a side sliding rod; 12. a side chute; 13. screening the frame; 14. vibrating the spring; 15. a vibration plate; 16. a connecting pipe; 17. a fixing plate; 18. a transmission rod; 19. an internal chute; 20. an intermediate rotating shaft; 21. a stirring rod; 22. a middle chute; 23. a limiting block; 24. a telescopic rod; 25. a built-in rod; 26. a dredging plate; 27. screening a screen; 28. a rotating drum; 29. an external gear; 30. a side gear; 31. an adjusting block; 32. a threaded rod.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Referring to fig. 1-7, the present invention provides a technical solution: a gravel screening device for swing type bridge construction comprises a support 1, a conveying pipe 2, a side conveying shaft 3, a middle conveying shaft 4, a disc 5, a push rod 6, a top sliding rod 7, a top sliding groove 8, a transmission disc 9, a fixing ring 10, a side sliding rod 11, a side sliding groove 12, a screening frame 13, a vibration spring 14, a vibration plate 15, a connecting pipe 16, a fixing plate 17, a transmission rod 18, an inner sliding groove 19, a middle rotating shaft 20, a stirring rod 21, a middle sliding groove 22, a limiting block 23, a telescopic rod 24, a built-in rod 25, a dredging plate 26, a screen 27, a rotary drum 28, an external gear 29, a side gear 30, an adjusting block 31 and a threaded rod 32, wherein the conveying pipe 2 is fixedly installed on the outer side surface of the support 1, the side conveying shaft 3 is rotatably connected to the inner side of the conveying pipe 2, the middle conveying shaft 4 is rotatably installed at the inner middle position of the conveying pipe 2, a push rod 6 is movably arranged on the inner side of the disc 5, a top sliding rod 7 is fixedly arranged on the lower surface of the push rod 6, the top sliding rod 7 is connected with the conveying pipe 2 through a top sliding groove 8, the top sliding groove 8 is arranged on the upper surface of the conveying pipe 2, a transmission disc 9 is rotatably arranged on the upper surface of the conveying pipe 2, a fixing ring 10 is welded on the outer side of the upper end of the conveying pipe 2, a side sliding rod 11 is fixedly arranged on the inner side of the bracket 1, the side sliding rod 11 is connected with the screening frame 13 through a side sliding groove 12, the side sliding grooves 12 are symmetrically arranged on two outer sides of the screening frame 13, the inner side of the bracket 1 is connected with a vibration plate 15 through a vibration spring 14, a connecting pipe 16 is fixedly arranged at the middle position of the lower end of the conveying pipe 2, a fixing plate 17 is welded, inside reservation of transfer line 18 has inside spout 19, and pivot 20 in the middle of swing joint has in inside spout 19, puddler 21 symmetry is fixed in the outside both sides of connecting pipe 16, and inside spout 22 in the middle of having seted up in the side of puddler 21, and swing joint has stopper 23 in the middle spout 22, telescopic link 24 and transfer line 18 interconnect are passed through to the outside of stopper 23, and the inboard of stopper 23 is through built-in pole 25 and mediation board 26 interconnect, the inside fixed mounting in lower surface of screening frame 13 has screen cloth 27, the outside of push rod 6 is rotated and is connected with rotary drum 28, and the outside intermediate position welding of rotary drum 28 has outside gear 29, and the side movable mounting of outside gear 29 has side gear 30.

In the embodiment, the push rod 6 is rotatably connected with the disc 5, the push rod 6 and the conveying pipe 2 form a sliding structure through the top sliding rod 7 and the top sliding groove 8, and the push rod 6 slides in the top sliding groove 8 through the top sliding rod 7 in the transmission process, so that the structure is more stable;

the inner side of the transmission disc 9 is movably connected with an adjusting block 31, a threaded rod 32 is movably arranged inside the left side of the adjusting block 31, the threaded rod 32 is in threaded connection with the transmission disc 9, the rotary drum 28 and the push rod 6, the side gear 30 is controlled to rotate by operating a motor, the rotary drum 28 is controlled to rotate under the meshing transmission action of the side gear 30 and the external gear 29, the threaded rod 32 rotates to enter the inner side of the adjusting block 31, and the threaded rod 32 is fixed inside the left side of the adjusting block 31 in a threaded rotating mode;

the screening frame 13 forms a sliding structure through the side sliding grooves 12 and the side sliding rods 11, the side sliding grooves 12 are of arc-shaped structures, the screening frame 13 forms a rotating structure through the transmission rod 18 and the fixing plate 17, the transmission rod 18 pushes the screening frame 13 fixed at the lower end to reciprocally swing left and right in the reciprocating rotation process, and the side sliding rods 11 slide in the side sliding grooves 12 at the moment to reinforce the swinging stability of the screening frame 13;

the screening frame 13 and the conveying pipe 2 form a mutual communication structure through the connecting pipe 16, the inner lower surface of the upper end of the conveying pipe 2 is of an inclined structure, the height of the lower surface of the left side of the inner part of the conveying pipe 2 is lower than that of the lower surface of the right side of the inner part of the conveying pipe 2, the part of the communication structure is convenient for controlling the feeding and discharging of sand stones through mechanical transmission, and the use is labor-saving;

the vibrating plate 15 and the support 1 form an elastic structure through the vibrating spring 14, the position of the vibrating plate 15 corresponds to the position of the fixing ring 10, the vibrating plate 15 is pushed to move upwards when the screening frame 13 swings in a reciprocating mode, the vibrating plate 15 vibrates up and down under the elastic action of the vibrating spring 14, vibration generated by the vibrating plate 15 affects the conveying pipe 2 on the inner side of the fixing ring 10, the conveying pipe 2 at the section generates local vibration, the sand and stone structure conveyed inside the conveying pipe 2 can be relatively prevented from being blocked on the inner side of the device, and the smoothness of sand and stone conveying is improved;

the middle rotating shaft 20 and the transmission rod 18 form a sliding structure through the inner chute 19, the middle rotating shaft 20 is of a Z-shaped structure, the transmission rod 18 and the limiting block 23 form a telescopic structure through the telescopic rod 24, the limiting block 23 and the stirring rod 21 form a sliding structure through the middle chute 22, the inner side and the outer side of the limiting block 23 are respectively fixedly connected with the telescopic rod 24 and the built-in rod 25, the dredging plate 26 and the stirring rod 21 form a telescopic structure through the built-in rod 25, 2 dredging plates 26 are symmetrically arranged on the center of the screening frame 13, the dredging plates 26 are connected with the screen 27 in a clamping manner, the transmission rod 18 drives the telescopic rod 24 to change in height in the rotating process, the telescopic rod 24 pushes the limiting block 23 to slide in the middle chute 22, the limiting block 23 drives the built-in rod 25 on the inner side to move in the stirring rod 21 in a telescopic manner, the built-in rod 25 drives the, the dredging plate 26 is in clamping contact with the screen mesh 27 discontinuously, so that part of sandstone structures blocked in the screen mesh 27 is dredged, and the using fluency of the device is further improved.

The working principle is as follows: when the device is used, firstly, according to the structure shown in figures 1, 2, 5, 6 and 7, when in feeding, the operation motor controls the side gear 30 to rotate, the side gear 30 is meshed with the external gear 29, the drum 28 is controlled to rotate under the action of gear meshing transmission, the drum 28 is in threaded connection with the threaded rod 32, the threaded rod 32 is controlled to rotate to enter the inner side of the adjusting block 31 under the action of the threaded transmission, the threaded rod 32 is in threaded rotation and fixed in the left inner part of the adjusting block 31, then the left inlet of the conveying pipe 2 corresponds to the feeding device, the operation motor controls the driving disc 9 to rotate, the driving disc 9 pushes the disc 5 to simultaneously rotate in the same direction through the push rods 6 and the threaded rods 32 at two sides, so as to drive the side conveying shaft 3 and the middle conveying shaft 4 corresponding to rotate and operate (the rotation directions of the side conveying shaft 3 and the middle conveying shaft 4 are opposite), the side conveying shaft 3 conveys the raw material upwards into the conveying pipe 2 in the, the inner lower surface of the upper end of the conveying pipe 2 is of an inclined structure, gravel materials move towards the lower right side, then the gravel raw materials are conveyed downwards to enter the inside of the screening frame 13 under the reverse rotation action of the middle conveying shaft 4, the middle rotating shaft 20 is controlled to rotate by the operation motor, the middle rotating shaft 20 is in sliding connection with the transmission rod 18 through the inner sliding groove 19, the screening frame 13 is pushed to swing in a reciprocating manner through the transmission rod 18 under the driving action, the side sliding rods 12 slide back and forth in the side sliding grooves 11 when the screening frame 13 swings, the gravel structures in the screening frame 13 are shaken and screened, fine sand is separated through the screen 27, the sand structures at the receiving part of the lower end of the screening frame 13 are received by using the receiving device, after the screening processing is finished, the threaded rod 32 is controlled to move towards the outer side in a reverse direction, so that the threaded rod 32 is separated from the adjusting, the middle conveying shaft 4 conveys the residual large stone structures in the screening frame 13 upwards, the stones enter the right side of the conveying pipe 2 and slide and are discharged rightwards under the action of the inclined surface, and the part of the transmission mechanism can control the classified derivation of the gravel structures through a mechanical transmission structure, so that the labor is saved, and the use is convenient;

subsequently, according to the structure shown in fig. 1, fig. 2, fig. 3, fig. 4 and fig. 5, during the sand screening process, the screening frame 13 swings reciprocally, the screening frame 13 pushes the vibration plate 15 upwards to move upwards during the process of rotating to the left, when the screening frame 13 rotates to the right, the vibration plate 15 vibrates up and down under the elastic action of the vibration spring 14, the vibration generated by the vibration plate 15 affects the conveying pipe 2 inside the fixing ring 10, the conveying pipe 2 at this section generates local vibration, the sand structure conveyed inside the conveying pipe 2 can be relatively prevented from being blocked inside the device, the smoothness of sand conveying is improved, meanwhile, the transmission rod 18 drives the height of the telescopic rod 24 to change during the rotation, the telescopic rod 24 pushes the limiting block 23 to slide in the middle chute 22, the limiting block 23 drives the internal rod 25 at the inner side to move telescopically in the stirring rod 21, the internal rod 25 drives the dredging plate 26 at the outer side to move back and forth along the direction of the stirring rod 21, dredge 26 discontinuity of board and screen cloth 27 block contact, dredge the inside partial grit structure that blocks up of screen cloth 27, further improve the smoothness nature that the device used for the device can normal continuity screening grit structure, improves the processing effect.

Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.

Claims

1. The utility model provides a grit sieving mechanism of oscillating bridge construction usefulness, includes support (1), top slide bar (7), connecting pipe (16) and puddler (21), its characterized in that: the outer side face of the support (1) is fixedly provided with a conveying pipe (2), the left side of the conveying pipe (2) is internally connected with a side conveying shaft (3) in a rotating mode, the inner middle position of the conveying pipe (2) is rotated to be provided with a middle conveying shaft (4), the upper surface of the side conveying shaft (3) and the upper surface of the middle conveying shaft (4) are welded with a disc (5), the inner side of the disc (5) is movably provided with a push rod (6), the lower surface of the push rod (6) is fixedly provided with a top sliding rod (7), the top sliding rod (7) is mutually connected with the conveying pipe (2) through a top sliding groove (8), the top sliding groove (8) is arranged on the upper surface of the conveying pipe (2), the upper surface of the conveying pipe (2) is rotatably provided with a transmission disc (9), the outer side of the upper end of the conveying pipe (2) is welded with a fixing, and the side sliding rods (11) are connected with the screening frame (13) through side sliding grooves (12), the side sliding grooves (12) are symmetrically arranged on two outer sides of the screening frame (13), the inner side of the bracket (1) is connected with the vibration plate (15) through the vibration spring (14), the connecting pipe (16) is fixedly arranged at the middle position of the lower end of the conveying pipe (2), the outer part of the connecting pipe (16) is welded with a fixing plate (17), the fixing plate (17) is connected with the screening frame (13) through a transmission rod (18), an inner sliding groove (19) is reserved inside the transmission rod (18), an intermediate rotating shaft (20) is movably connected in the inner sliding groove (19), the stirring rods (21) are symmetrically fixed on two outer sides of the connecting pipe (16), an intermediate sliding groove (22) is arranged inside the side surface of the stirring rod (21), and a limit block (23) is movably connected in the intermediate sliding groove (22), the outside of stopper (23) is through telescopic link (24) and transfer line (18) interconnect, and the inboard of stopper (23) is through built-in pole (25) and dredge board (26) interconnect, the inside fixed mounting of lower surface of screening frame (13) has screen cloth (27), the outside of push rod (6) is rotated and is connected with rotary drum (28), and the outside intermediate position welding of rotary drum (28) has external gear (29) to the side movable mounting of external gear (29) has side gear (30).

2. The sand screening device for the swing type bridge construction according to claim 1, characterized in that: the push rod (6) is rotatably connected with the disc (5), and the push rod (6) forms a sliding structure with the conveying pipe (2) through a top sliding rod (7) and a top sliding groove (8).

3. The sand screening device for the swing type bridge construction according to claim 1, characterized in that: the inner side of the transmission disc (9) is movably connected with an adjusting block (31), a threaded rod (32) is movably arranged inside the left side of the adjusting block (31), and the threaded rod (32) is in threaded connection with the transmission disc (9), the rotary drum (28) and the push rod (6).

4. The sand screening device for the swing type bridge construction according to claim 1, characterized in that: the screening frame (13) forms a sliding structure through a side sliding groove (12) and a side sliding rod (11), the side sliding groove (12) is of an arc-shaped structure, and the screening frame (13) forms a rotating structure through a transmission rod (18) and a fixing plate (17).

5. The sand screening device for the swing type bridge construction according to claim 1, characterized in that: screening frame (13) are through connecting pipe (16) and conveyer pipe (2) constitution intercommunication structure each other, and conveyer pipe (2) upper end inside lower surface be the slope column structure to conveyer pipe (2) inside left side lower surface height is less than conveyer pipe (2) inside right side lower surface height.

6. The sand screening device for the swing type bridge construction according to claim 1, characterized in that: the vibration plate (15) and the bracket (1) form an elastic structure through the vibration spring (14), and the position of the vibration plate (15) corresponds to the position of the fixing ring (10).

7. The sand screening device for the swing type bridge construction according to claim 1, characterized in that: the middle rotating shaft (20) and the transmission rod (18) form a sliding structure through the inner sliding groove (19), the middle rotating shaft (20) is of a Z-shaped structure, and the transmission rod (18) and the limiting block (23) form a telescopic structure through the telescopic rod (24).

8. The sand screening device for the swing type bridge construction according to claim 1, characterized in that: the limiting block (23) and the stirring rod (21) form a sliding structure through the middle sliding groove (22), and the inner side and the outer side of the limiting block (23) are fixedly connected with the telescopic rod (24) and the built-in rod (25) respectively.

9. The sand screening device for the swing type bridge construction according to claim 1, characterized in that: the dredging plate (26) and the stirring rod (21) form a telescopic structure through the built-in rod (25), 2 dredging plates (26) are symmetrically arranged around the center of the screening frame (13), and the dredging plate (26) is connected with the screen (27) in a clamping mode.