Downhole float collar capable of preventing sand and stone blockage

Abstract

The invention is applicable to the field, and provides a gravel blockage prevention float collar for well drilling, which comprises an outer conical cylinder, a butt joint pipe and a cylinder body, the outer conical cylinder is located at the bottom of the cylinder body, the butt joint pipe is located at the top of the cylinder body, and a clamping assembly is arranged between the cylinder body and the butt joint pipe; openings are formed in the bottoms of the outer conical cylinder and the inner conical cylinder, and when a valve in the cylinder needs to be closed, the electric push rod drives the inner conical cylinder to be pushed upwards by a certain distance till the inner conical cylinder and the sealing cone are attached together. The motor drives the sealing cone to rotate at the moment, stones in the gap between the inner cone cylinder and the sealing cone can be ground in the rotating process, and the stones in the gap between the inner cone cylinder and the sealing cone can be ground into fine powder; in this way, the inner cone cylinder and the sealing cone can be attached more tightly in a clearance mode, and therefore the risk of liquid leakage is reduced.

Description

Technical Field

[0001] The invention belongs to the field of drilling rigs, and particularly relates to a floating collar for preventing sand and gravel blockage. Background Art

[0002] With the development of industrial technology, modern technology has become more and more perfect. Float collar and float shoe are a kind of casing guide shoe or coupling that can generate buoyancy. Because the float shoe or float collar is resistant to high temperature, has good sealing and drillability, and is easy to connect, there is a valve in the float collar. The closure of this valve can block the material underground. There will be a lot of sand and gravel in the mine during mining. If large sand and gravel enter the valve, it will cause the valve to be unable to close. Patent CN216841556U discloses a highly sealing floating collar and floating shoe, which relates to the field of oil well drilling technology and includes a pipeline, wherein fastening cement is fixedly installed at both ends of the pipeline, a support frame is fixedly installed inside the fastening cement, a valve assembly is detachably installed inside the support frame, and a connecting block is fixedly installed at the bottom of the support frame. In the above scheme, during the operation of the device, the sealing strip is pressed down by the spring assembly and contacts the position plate. As the position plate descends, the rubber pad wraps around the sealing strip to complete the sealing. At the same time, the ball valve itself blocks the sealing port to complete the double sealing. When the device is maintained or repaired and replaced, the support frame is sleeved and installed on the valve assembly. The support frame is pressed and rotated, and under the action of the spring assembly, the support frame is directly fixed inside the locking groove, which is convenient for subsequent repairs and maintenance, and has stronger sealing, making the floating collar and floating shoe more effective, the cementing quality higher, and the construction safer. This device still has defects when in use. First, when the mine is excavated, many stones may fall off the side walls of the mine, and large particles of matter may easily get stuck in the valve gap of the existing float collar device, which makes it impossible to completely close the valve. Second, the pipe and float collar of the existing float collar device need to be locked with bolts, which requires a lot of manpower to operate and increases labor costs. Summary of the Invention

[0003] The purpose of the present invention is to address the deficiencies in the prior art and provide a floating collar for drilling that prevents sand and gravel blockage. When the device is in use, when the valve inside the cylinder needs to be closed, the electric push rod drives the inner cone to advance a distance until the inner cone and the sealing cone fit together. If large stones appear in the gap between the inner cone and the sealing cone, this will cause the gap between the inner cone and the sealing cone to not be completely closed. At this time, the motor drives the sealing cone to start rotating, and the stones inside the gap between the inner cone and the sealing cone will be ground during the rotation. The stones inside the gap between the inner cone and the sealing cone will be ground into fine powder, which can make the gap between the inner cone and the sealing cone fit more tightly, thereby reducing the risk of leakage, thereby solving the problems mentioned in the background technology.

[0004] To solve the above problems, the present invention provides the following technical solutions: a floating collar for drilling to prevent sand and gravel blockage, comprising an outer cone, a butt tube and a cylinder, the outer cone being at the bottom of the cylinder, the butt tube being at the top of the cylinder, a clamping assembly being provided between the cylinder and the butt tube; an inner cone being slidably provided inside the cylinder, the bottoms of the outer cone and the inner cone being both provided with openings, the openings at the bottom of the outer cone and the openings at the bottom of the inner cone being sealed and connected by a sealing sac, a closed space being formed between the outer cone, the inner cone, the cylinder and the sealed sac, two electric push rods being provided in the closed space, the bottoms of the electric push rods being fixed on the inner side wall of the outer cone, and the telescopic rods of the electric push rods being connected to the outer side wall of the inner cone; a motor being further provided inside the outer cone, the top of the motor being fixedly connected to the inner side wall of the outer cone through a connecting frame, a sealing cone being provided on the output shaft of the motor, and the outer side wall of the sealing cone and the inner side wall of the inner cone being able to be sealed and fitted.

[0005] During use, when the valve inside the cylinder needs to be closed, the electric push rod drives the inner cone upward for a distance until the inner cone and the sealing cone fit together. If large stones appear in the gap between the inner cone and the sealing cone, this will cause the gap between the inner cone and the sealing cone to not be completely closed. At this time, the motor drives the sealing cone to start rotating, and the stones inside the gap between the inner cone and the sealing cone will be ground during the rotation. The stones inside the gap between the inner cone and the sealing cone will be ground into fine powder, which can make the gap between the inner cone and the sealing cone fit more tightly, thereby reducing the risk of leakage.

[0006] Furthermore, the top edge of the sealed sac and the bottom opening of the inner cone are heat-fused together, and the bottom edge of the sealed sac and the bottom opening of the outer cone are heat-fused together. The material of the sealed sac is rubber.

[0007] When in use, a closed space is formed between the outer cone, the inner cone, the cylinder body and the closed sac. This closed space can protect the electric push rod from interference from the slurry, thereby reducing the failure rate of the electric push rod.

[0008] Furthermore, the inner side wall of the inner cone is provided with three annular grooves, the openings of the annular grooves are provided with a layer of diaphragm, the edge of the diaphragm is tightly connected to the openings of the annular grooves, and an air blowing assembly is provided inside the annular grooves.

[0009] During use, negative pressure is generated inside the three annular grooves during the grinding process of the gap between the inner cone and the sealing cone, which can cause the diaphragm to form an inward concave state. Therefore, the diaphragm will not be touched during the grinding process, which can prevent the diaphragm from being scratched. When the gap between the inner cone and the sealing cone is closed, high pressure is generated inside the three annular grooves, and the diaphragm will expand and bulge, which can make the seal between the inner cone and the sealing cone tighter.

[0010] Furthermore, the air blowing assembly includes true eye air holes on the inner wall of the annular groove, three true eye air holes are connected in series and connected to an air pipe, the air pipe is connected to the output end of the air pump, and the air pump is fixed on the inner wall of the outer cone.

[0011] When in use, the air pump provides pressure support to the inside of the annular groove through the air pipe. When the air pump extracts air through the air pipe, the diaphragm forms an inward concave state. When the air pump inflates air through the air pipe, the diaphragm forms an inward convex state.

[0012] Furthermore, the snap-on assembly includes a snap-on tube at the bottom of the docking tube, the outer diameter of the snap-on tube is smaller than the inner diameter of the cylinder, the snap-on tube is inserted from the top of the cylinder, the outer diameter of the docking tube is equal to the outer diameter of the cylinder, the bottom of the snap-on tube abuts against the top surface of the connecting frame, and a snap-on assembly is provided on the outer side wall of the snap-on tube.

[0013] When in use, the butt joint pipe and the locking pipe are inserted into the top of the cylinder for installation, and then the snap assembly is locked.

[0014] Furthermore, the snap assembly includes a T-slot on the outer side wall of the butt tube, and a turning groove is further provided at the upper end of the T-slot. The cross-sections of the T-slot and the turning groove are the same, and a clamping block is provided on the inner side wall of the cylinder. The end of the clamping block is provided with a clamping piece. The clamping block and the clamping piece can be laterally inserted into the interior of the T-slot and the turning groove. The clamping block and the clamping piece can be inserted into the turning groove at a certain angle, and a blocking mechanism is provided inside the T-slot.

[0015] When in use, when the butt-jointed tube and the clamping tube are inserted from the top of the cylinder, the clamping block and the clamping piece are aligned with the end of the T-slot, and the clamping block and the clamping piece begin to twist at the position of the bend groove and insert into the bend groove.

[0016] Furthermore, the blocking mechanism includes a sedimentation trough at the bottom of the T-slot, a sealing strip is movably provided inside the sedimentation trough, the sealing strip and the inner side wall of the sedimentation trough are connected by a reset spring, and a slope is provided at the outer end of the sealing strip.

[0017] When in use, the clamping block and the clamping piece are aligned with the port of the T-slot, and the clamping piece first contacts the slope of the outer end of the blocking strip. As the clamping block and the clamping piece slide into the T-slot, the blocking strip will be pressed down. When the clamping block and the clamping piece enter the turning groove, the blocking strip will pop up to block the retreat of the clamping block and the clamping piece. This assembly method does not require the operation of tightening bolts, saving manpower.

[0018] Compared with the prior art, the embodiments of the present application have the following beneficial effects: Firstly, when the device is in use, when the valve inside the cylinder needs to be closed, the electric push rod drives the inner cone upward for a distance until the inner cone and the sealing cone fit together. If large stones appear in the gap between the inner cone and the sealing cone, this will cause the gap between the inner cone and the sealing cone to not be completely closed. At this time, the motor drives the sealing cone to start rotating, and the stones inside the gap between the inner cone and the sealing cone will be ground during the rotation. The stones inside the gap between the inner cone and the sealing cone will be ground into fine powder, which can make the gap between the inner cone and the sealing cone fit more tightly, thereby reducing the risk of leakage.

[0019] Secondly, during the grinding process of the gap between the inner cone and the sealing cone, negative pressure is generated inside the three annular grooves, which can make the diaphragm form an inward concave state. Therefore, during the grinding process, the diaphragm will not be touched, which can prevent the diaphragm from being scratched. When the gap between the inner cone and the sealing cone is closed, high pressure is generated inside the three annular grooves, and the diaphragm will expand and bulge, which can make the seal between the inner cone and the sealing cone tighter.

[0020] Third, the clamping block and the clamping piece are aligned with the port of the T-slot. The clamping piece first contacts the slope of the outer end of the blocking strip. When the clamping block and the clamping piece slide into the T-slot, the blocking strip will be pressed down. When the clamping block and the clamping piece enter the turning groove, the blocking strip will pop up to block the retreat of the clamping block and the clamping piece. This assembly method does not require the operation of tightening bolts, saving manpower. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic diagram of a cross-section of the present invention.

[0022] Figure 2 It is a schematic diagram of the cylinder of the present invention.

[0023] Figure 3 It is a schematic diagram of the outer cone of the present invention.

[0024] Figure 4 Schematic diagram of the sealed capsule of the present invention.

[0025] Figure 5 Schematic diagram of the sealing cone of the present invention.

[0026] Figure 6 It is a schematic diagram of the inner cone of the present invention.

[0027] Figure 7 For the present invention Figure 6 A partial enlarged view of .

[0028] Figure 8 Schematic diagram of the butt joint of the present invention.

[0029] Figure 9 For the present invention Figure 8 B is a partial enlarged view of .

[0030] Description of reference numerals: Outer cone 1, docking tube 2, locking tube 201, electric push rod 3, inner cone 4, annular groove 401, diaphragm 402, sealing cone 5, cylinder 6, snap-on piece 7, motor 8, connecting frame 801, sealed sac 9, air pump 10, air delivery pipe 1001, T-slot 11, turning groove 1101, sedimentation tank 1102, sealing strip 1103, slope 1104. DETAILED DESCRIPTION

[0031] Unless otherwise defined, all technical and scientific terms used herein have the same meanings as commonly understood by those skilled in the art to which this application belongs. The terms used in the specification of the application are only for the purpose of describing specific embodiments and are not intended to limit this application. The terms "including" and "having" and any variations thereof in the specification and claims of this application and the above-mentioned drawings are intended to cover non-exclusive inclusions. The terms "first", "second", etc. in the specification and claims of this application or the above-mentioned drawings are used to distinguish different objects, not to describe a specific order.

[0032] References herein to "embodiments" mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least one embodiment of the present application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0033] The present invention provides a floating collar for drilling to prevent sand and gravel blockage, such as Figure 1-9 As shown, it includes an outer cone 1, a butt joint tube 2 and a cylinder 6, wherein the outer cone 1 is at the bottom of the cylinder 6, the butt joint tube 2 is at the top of the cylinder 6, and a clamping assembly is provided between the cylinder 6 and the butt joint tube 2; an inner cone 4 is provided inside the cylinder 6 for sliding, and the bottoms of the outer cone 1 and the inner cone 4 are both provided with openings, and the opening at the bottom of the outer cone 1 and the opening at the bottom of the inner cone 4 are sealed and connected by a sealed capsule 9, and the outer cone 1, the inner cone 4, the cylinder 6 and the sealed capsule 9 are sealed and connected. A closed space is formed between them, and two electric push rods 3 are arranged in the closed space. The bottom of the electric push rod 3 is fixed on the inner wall of the outer cone 1, and the telescopic rod of the electric push rod 3 is connected to the outer wall of the inner cone 4; a motor 8 is also provided inside the outer cone 1, and the top of the motor 8 is fixedly connected to the inner wall of the outer cone 1 through a connecting frame 801, and a sealing cone 5 is provided on the output shaft of the motor 8, and the outer wall of the sealing cone 5 and the inner wall of the inner cone 4 can be tightly fitted.

[0034] In this embodiment, when the valve inside the cylinder 6 needs to be closed, the electric push rod 3 drives the inner cone 4 to advance a certain distance until the inner cone 4 and the sealing cone 5 are fitted together. If large stones appear in the gap between the inner cone 4 and the sealing cone 5, this will cause the gap between the inner cone 4 and the sealing cone 5 to not be completely closed. At this time, the motor 8 drives the sealing cone 5 to start rotating, and the stones inside the gap between the inner cone 4 and the sealing cone 5 will be ground during the rotation. The stones inside the gap between the inner cone 4 and the sealing cone 5 will be ground into fine powder, which can make the gap between the inner cone 4 and the sealing cone 5 fit more tightly, thereby reducing the risk of leakage.

[0035] In a further embodiment of the present invention, Figure 1-5 As shown, the top edge of the sealed sac 9 and the bottom opening of the inner cone 4 are hot-fused together, and the bottom edge of the sealed sac 9 and the bottom opening of the outer cone 1 are hot-fused together. The material of the sealed sac 9 is rubber.

[0036] In this embodiment, a closed space is formed between the outer cone 1, the inner cone 4, the cylinder 6 and the closed capsule 9. This closed space can protect the electric push rod 3 from interference from the slurry, thereby reducing the failure rate of the electric push rod 3.

[0037] In a further embodiment of the present invention, Figure 6-7 As shown, the inner wall of the inner cone 4 is provided with three annular grooves 401 , the opening of the annular groove 401 is provided with a layer of diaphragm 402 , the edge of the diaphragm 402 is tightly connected to the opening of the annular groove 401 , and an air blowing component is provided inside the annular groove 401 .

[0038] In this embodiment, during the grinding process of the gap between the inner cone 4 and the sealing cone 5, negative pressure is generated inside the three annular grooves 401, which can cause the diaphragm 402 to be concave inward, and thus during the grinding process, the diaphragm 402 will not be touched, which can prevent the diaphragm 402 from being scratched. When the gap between the inner cone 4 and the sealing cone 5 is closed, high pressure is generated inside the three annular grooves 401, and then the diaphragm 402 will expand and bulge, which can make the seal between the inner cone 4 and the sealing cone 5 tighter.

[0039] In a further embodiment of the present invention, Figure 3-7 As shown, the air blowing assembly includes true eye air holes on the inner wall of the annular groove 401, three true eye air holes are connected in series and connected to an air pipe 1001, and the air pipe 1001 is connected to the output end of the air pump 10, and the air pump 10 is fixed on the inner wall of the outer cone 1.

[0040] In this embodiment, the air pump 10 provides pressure support to the interior of the annular groove 401 through the air pipe 1001. When the air pump 10 extracts air through the air pipe 1001, the diaphragm 402 forms an inward concave state. When the air pump 10 inflates air through the air pipe 1001, the diaphragm 402 forms an inward convex state.

[0041] In a further embodiment of the present invention, Figure 8-9 As shown, the snap-fit ​​assembly includes a snap-fit ​​tube 201 at the bottom of the connecting tube 2, the outer diameter of the snap-fit ​​tube 201 is smaller than the inner diameter of the cylinder 6, the snap-fit ​​tube 201 is inserted from the top of the cylinder 6, the outer diameter of the connecting tube 2 is equal to the outer diameter of the cylinder 6, the bottom of the snap-fit ​​tube 201 abuts against the top surface of the connecting frame 801, and a snap-fit ​​assembly is provided on the outer wall of the snap-fit ​​tube 201.

[0042] In this embodiment, the butt joint pipe 2 and the locking pipe 201 are inserted from the top end of the cylinder 6 for installation, and then the buckle assembly is locked.

[0043] In a further embodiment of the present invention, Figure 8-9 As shown, the snap assembly includes a T-slot 11 on the outer wall of the butt tube 2, and a turning groove 1101 is further provided at the upper end of the T-slot 11. The cross-sections of the T-slot 11 and the turning groove 1101 are the same, and a clamping block is provided on the inner wall of the cylinder 6. The end of the clamping block is provided with a clamping piece 7. The clamping block and the clamping piece 7 can be laterally inserted into the interior of the T-slot 11 and the turning groove 1101. The clamping block and the clamping piece 7 can be inserted at a certain angle at the position of the turning groove 1101, and a blocking mechanism is provided inside the T-slot 11.

[0044] In this embodiment, when the connecting tube 2 and the locking tube 201 are inserted from the top of the cylinder 6, the locking block and the locking piece 7 are aligned with the port of the T-slot 11, and the locking block and the locking piece 7 begin to twist at the position of the turning groove 1101 and are inserted into the turning groove 1101.

[0045] In a further embodiment of the present invention, Figure 8-9 As shown, the blocking mechanism includes a sedimentation trough 1102 at the bottom of the T-slot 11, and a blocking bar 1103 is movably provided inside the sedimentation trough 1102. The blocking bar 1103 and the inner wall of the sedimentation trough 1102 are connected by a reset spring, and the outer end of the blocking bar 1103 is provided with a slope 1104.

[0046] In this embodiment, the clamping block and the clamping piece 7 are aligned with the port of the T-slot 11, and the clamping piece 7 first contacts the slope 1104 at the outer end of the blocking strip 1103. When the clamping block and the clamping piece 7 slide into the T-slot 11, the blocking strip 1103 will be pressed down. When the clamping block and the clamping piece 7 enter the turning groove 1101, the blocking strip 1103 will pop up to block the retreat of the clamping block and the clamping piece 7. This assembly method does not require the operation of tightening bolts, saving human resources.

[0047] It should be noted that for the aforementioned embodiments, for simplicity of description, they are all expressed as a series of action combinations. However, those skilled in the art should be aware that the present invention is not limited by the order of the actions described, because according to the present invention, certain steps may be performed in other orders or simultaneously. Secondly, those skilled in the art should also be aware that the embodiments described in this specification are all preferred embodiments, and the actions and modules involved are not necessarily required by the present invention.

[0048] In the several embodiments provided in this application, it should be understood that the disclosed devices can be implemented in other ways. For example, the device embodiments described above are merely illustrative, such as the division of the above-mentioned units. In actual implementation, there may be other division methods, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the coupling or communication connection between each other shown or discussed can be through some interfaces, and the indirect coupling or communication connection between devices or units can be in the form of telecommunications or other forms.

[0049] The units described above as separate components may or may not be physically separate, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed across multiple network units. Some or all of these units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0050] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the scope of protection of the invention. Obviously, the embodiments described are only some embodiments of the present invention, rather than all embodiments. Based on these embodiments, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in this field can still combine, add, delete or make other adjustments to the features in the various embodiments of the present invention according to the circumstances without conflict, without making creative work, so as to obtain different other technical solutions that do not deviate from the concept of the present invention in essence, and these technical solutions also fall within the scope of protection of the present invention.

Claims

1. A floating collar for drilling to prevent sand and gravel blockage, comprising an outer cone (1), a butt-jointed tube (2) and a cylinder (6), characterized in that: The outer cone (1) is located at the bottom of the cylinder (6), the butt joint (2) is located at the top of the cylinder (6), and a clamping assembly is provided between the cylinder (6) and the butt joint (2); An inner cone (4) is slidably provided inside the cylinder (6), and the bottoms of the outer cone (1) and the inner cone (4) are both provided with openings. The opening at the bottom of the outer cone (1) and the opening at the bottom of the inner cone (4) are sealed and connected via a sealed capsule (9). A closed space is formed between the outer cone (1), the inner cone (4), the cylinder (6) and the sealed capsule (9), and two electric push rods (3) are provided in the closed space. The bottoms of the electric push rods (3) are fixed to the inner side wall of the outer cone (1), and the telescopic rods of the electric push rods (3) are connected to the outer side wall of the inner cone (4); A motor (8) is further provided inside the outer conical cylinder (1), and the top of the motor (8) is fixedly connected to the inner wall of the outer conical cylinder (1) via a connecting frame (801). A sealing cone (5) is provided on the output shaft of the motor (8), and the outer wall of the sealing cone (5) and the inner wall of the inner conical cylinder (4) can be tightly fitted.

2. The floating collar for drilling to prevent sand and gravel blockage according to claim 1, characterized in that: The top edge of the sealed sac (9) and the bottom opening of the inner cone (4) are heat-fused together, and the bottom edge of the sealed sac (9) and the bottom opening of the outer cone (1) are heat-fused together. The material of the sealed sac (9) is rubber.

3. The floating collar for drilling to prevent sand and gravel blockage according to claim 1, characterized in that: The inner side wall of the inner cone (4) is provided with three annular grooves (401), the openings of the annular grooves (401) are provided with a diaphragm (402), the edges of the diaphragm (402) and the openings of the annular grooves (401) are tightly connected, and an air blowing assembly is provided inside the annular grooves (401).

4. The floating collar for drilling to prevent sand and gravel blockage according to claim 3, characterized in that: The air blowing assembly comprises true eye air holes on the inner side wall of the annular groove (401), three true eye air holes are connected in series and connected to an air delivery pipe (1001), the air delivery pipe (1001) is connected to the output end of the air pump (10), and the air pump (10) is fixed on the inner side wall of the outer cone (1).

5. The floating collar for drilling to prevent sand and gravel blockage according to claim 1, characterized in that: The snap-fit ​​assembly comprises a snap-fit ​​tube (201) at the bottom of the butt-joint tube (2), the outer diameter of the snap-fit ​​tube (201) being smaller than the inner diameter of the cylinder (6), the snap-fit ​​tube (201) being inserted into the cylinder (6) from the top, the outer diameter of the butt-joint tube (2) being equal to the outer diameter of the cylinder (6), the bottom of the snap-fit ​​tube (201) being in contact with the top surface of the connecting frame (801), and a snap-fit ​​assembly being provided on the outer side wall of the snap-fit ​​tube (201).

6. The floating collar for drilling to prevent sand and gravel blockage according to claim 5, characterized in that: The snap assembly comprises a T-slot (11) on the outer side wall of the butt-jointed tube (2), a turning groove (1101) being further provided at the upper end of the T-slot (11), the cross sections of the T-slot (11) and the turning groove (1101) being the same, a clamping block being provided on the inner side wall of the cylinder (6), a clamping piece (7) being provided at the end of the clamping block, the clamping block and the clamping piece (7) being capable of being laterally inserted into the interior of the T-slot (11) and the turning groove (1101), the clamping block and the clamping piece (7) being capable of being inserted into the turning groove (1101) by turning at a certain angle, and a blocking mechanism being provided inside the T-slot (11).

7. The floating collar for drilling to prevent sand and gravel blockage according to claim 6, characterized in that: The blocking mechanism comprises a sedimentation trough (1102) at the bottom of the T-shaped groove (11), a blocking strip (1103) being movably provided inside the sedimentation trough (1102), the blocking strip (1103) being connected to the inner side wall of the sedimentation trough (1102) via a return spring, and a slope (1104) being provided at the outer end of the blocking strip (1103).

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