Sand-sediment-prevention isolating device for oil pipe

Abstract

The utility model provides an oil pipe sand-prevention sediment isolation device which comprises an oil inlet pipe and an oil outlet pipe, the oil pipe sand-prevention sediment isolation device further comprises a sediment isolation assembly, the sediment isolation assembly collects and filters oil sediment guided out by the oil inlet pipe, when a first filtering piece is replaced, a second filtering piece starts to work, and when the first filtering piece is replaced, the second filtering piece starts to work; when the second filter part is replaced, the first filter part starts to work, the first filter part and the second filter part can be used alternately, when residual sand and stones in the first filter part are cleaned, the second filter part is started to filter oil, and similarly, when the sand and stones in the second filter part are cleaned, the second filter part is started to filter oil. The first filtering part is started to filter the oil, and the gravel in the first filtering part and the second filtering part can be cleaned under the condition that the whole oil way does not need to stop working.

Description

Technical Field

[0001] The utility model relates to the technical field of isolation devices, in particular to an isolation device for preventing sand and sediment in oil pipes. Background Art

[0002] During the use of oil pipes, they need to be lowered into wells to transport crude oil and natural gas from oil and gas layers to the surface. Oil pipes can withstand the pressure generated during the exploitation process and are mainly used for the transportation of produced liquid or injected liquid.

[0003] Among them, since the crude oil contains impurities such as sand and gravel, when using an oil pipe for transportation, the sand and gravel impurities in the crude oil are likely to block the oil pipe. Therefore, a filtering and isolating device is usually used to process the sand and gravel in the crude oil during the use of the oil pipe. The common filter element uses a filter cartridge. After long-term use, the sand and gravel will deposit on the filter cartridge. When cleaning the filter cartridge, it is necessary to close the oil pipe pipeline, resulting in a decrease in the oil transportation efficiency of the oil pipe. Therefore, we propose an isolation device for preventing sand and sediment in oil pipes. Content of the Utility Model

[0004] The purpose of the utility model is to provide an isolation device for preventing sand and sediment in oil pipes, which can complete the work of cleaning the deposited sand and gravel without closing the oil pipe pipeline.

[0005] The utility model provides an isolation device for preventing sand and sediment in oil pipes, including an inlet oil pipe and an outlet oil pipe. The isolation device for preventing sand and sediment in oil pipes further includes a sediment isolation component, and the sediment isolation component collects and filters the sediment in the oil discharged from the inlet oil pipe.

[0006] The sediment isolation component includes a mounting shell, a first filter element and a second filter element.

[0007] The mounting shell is connected to the bottom of the inlet oil pipe, and the bottom of the mounting shell is connected to the outlet oil pipe. The first filter element is used to filter the oil entering the mounting shell. When the first filter element is replaced, the second filter element starts to work. The second filter element is installed between the inlet oil pipe and the outlet oil pipe. When the second filter element is replaced, the first filter element starts to work.

[0008] Preferably, the first filter element includes a right-angle plate, a filter cartridge, a sealing member, a pressing member and a fixing member.

[0009] The right-angle plate is sleeved in the mounting shell, the filter cartridge is threadedly connected in the right-angle plate, the sealing member is fixedly connected to the right-angle plate, the sealing member is used to seal the mounting shell, the pressing member is arranged in the right-angle plate, the pressing member is used to close the bottom end of the inlet oil pipe, and the pressing member is connected to the right-angle plate through the fixing member.

[0010] Preferably, the seal includes a sealing plate, fixing pins, and guiding rods;

[0011] The sealing plate is fixedly connected to the right-angled plate. The sealing plate is connected to the mounting shell through the fixing pins. The guiding rods are fixedly connected to the sealing plate, and the guiding rods are sleeved and connected to the mounting shell.

[0012] Preferably, the pressing member includes a cylinder, a push rod, a rubber plate, and an elastic member;

[0013] The cylinder is mounted on the right-angled plate. The push rod is sleeved in the cylinder. The rubber plate is fixedly connected to the push rod. The elastic member is arranged in the cylinder.

[0014] Preferably, the fixing member includes a clamp and a bolt;

[0015] The clamp is fixedly connected to the cylinder. The clamp is connected to the right-angled plate through the bolt.

[0016] Preferably, the second filter element includes a guiding member, a storage member, and a return pipe;

[0017] The guiding member is used to guide the oil in the oil inlet pipe into the second filter element. The storage member is used to filter the sand and gravel in the oil in the guiding member. The return pipe guides the oil filtered by the storage member into the oil outlet pipe.

[0018] Preferably, the guiding member includes a guiding pipe, a control valve, and a connector;

[0019] The guiding pipe is communicated with the oil inlet pipe. The control valve is installed in the guiding pipe. The connector is installed on the guiding pipe, and the connector is connected to the storage member.

[0020] Preferably, the storage member includes a housing and a filter element;

[0021] The housing is threadedly connected to the connector. The filter element is threadedly connected in the housing.

[0022] Preferably, an opening and closing assembly is provided on the mounting shell;

[0023] The opening and closing assembly includes an end cover, a connecting member, and a rubber pad;

[0024] The end cover is installed on the mounting shell. The end cover is connected to the mounting shell through the connecting member. The rubber pad is fixedly connected to the end cover.

[0025] Preferably, the connecting member includes a screw rod, a limiting plate, and a nut;

[0026] The screw is fixedly connected to the end cover, the limiting plate is fixedly connected to the mounting shell, the limiting plate and the screw are sleeved and connected, and the nut is threadedly connected to the screw.

[0027] The utility model provides an oil pipe sand prevention and sediment isolation device through improvement. Compared with the prior art, it has the following improvements and advantages:

[0028] Through the combined use of the first filter element, the second filter element and the mounting shell, the first filter element and the second filter element can be used alternately. When cleaning the sand remaining inside the first filter element, start the second filter element to filter the oil. Similarly, when cleaning the sand in the second filter element, start the first filter element to filter the oil. Without stopping the operation of the entire oil circuit, the cleaning of the sand inside the first filter element and the second filter element can be completed, reducing the cleaning time and thus improving the oil transportation efficiency of the entire oil circuit. Description of the Drawings

[0029] In order to more clearly illustrate the specific embodiments of the present utility model or the technical solutions in the prior art, the following will briefly introduce the drawings required for use in the description of the specific embodiments or the prior art. Obviously, the following drawings are some embodiments of the present utility model. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0030] Figure 1 It is a schematic structural diagram of the present utility model;

[0031] Figure 2 It is a cross-sectional view of the mounting shell of the present utility model;

[0032] Figure 3 It is a schematic structural diagram of the outer shell, filter element and return pipe of the present utility model;

[0033] Figure 4 It is a schematic structural diagram of the rubber plate, ejector rod and elastic member of the present utility model;

[0034] Figure 5 It is a schematic structural diagram of the right-angle plate, filter cartridge and sealing plate of the present utility model;

[0035] Figure 6 It is a schematic structural diagram of the end cover, screw and rubber pad of the present utility model.

[0036] Explanation of the Reference Numerals:

[0037] 1 - Inlet pipe, 2 - Sediment isolation component, 21 - Installation shell, 22 - First filter element, 221 - Right-angle plate, 222 - Filter cartridge, 223 - Sealing component, 223a - Sealing plate, 223b - Fixing pin, 223c - Alignment rod, 224 - Tightening component, 224a - Cylinder, 224b - Push rod, 224c - Rubber plate, 224d - Elastic component, 225 - Fixing piece, 225a - Clamp, 225b - Bolt, 23 - Second filter element, 231 - Flow guiding component, 231a - Flow guiding pipe, 231b - Control valve, 231c - Connector, 232 - Storage component, 232a - Outer shell, 232b - Filter element, 233 - Return pipe, 3 - Outlet pipe, 4 - Opening and closing component, 41 - End cover, 42 - Connecting piece, 421 - Screw rod, 422 - Limiting plate, 423 - Nut, 43 - Rubber pad. Detailed implementation manners

[0038] The technical solutions of the present utility model will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are some, but not all, of the embodiments of the present utility model. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present utility model without creative efforts shall fall within the protection scope of the present utility model.

[0039] In the description of the present utility model, it should be understood that the orientation or positional relationships indicated by the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc. are based on the orientation or positional relationships shown in the drawings, and are only for the convenience of describing the present utility model and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present utility model.

[0040] In the description of the present utility model, it should be understood that the terms "first" - "second" are only for descriptive purposes and cannot be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" - "second" may explicitly or implicitly include one or more of the said features. In the description of the present utility model, the meaning of "a plurality" is two or more unless otherwise specifically defined. In addition, the terms "installation" - "connection" - "connection" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present utility model can be understood according to specific circumstances.

[0041] In this embodiment, as Figure 1 and Figure 2 shown, the tubing sand control and sediment isolation device includes an inlet tubing 1 and an outlet tubing 3. The tubing sand control and sediment isolation device further includes a sediment isolation assembly 2. The sediment isolation assembly 2 collects and filters the sediment in the oil fluid exported from the inlet tubing 1. The sediment isolation assembly 2 includes a mounting shell 21, a first filter element 22, and a second filter element 23. The mounting shell 21 is connected to the bottom of the inlet tubing 1, and the bottom of the mounting shell 21 is connected to the outlet tubing 3. The first filter element 22 is used to filter the oil fluid entering the mounting shell 21. When the first filter element 22 is replaced, the second filter element 23 starts to work. The second filter element 23 is installed between the inlet tubing 1 and the outlet tubing 3. When the second filter element 23 is replaced, the first filter element 22 starts to work.

[0042] Thus, the inlet tubing 1 and the outlet tubing 3 are respectively connected to the upper and lower ends of the mounting shell 21. The first filter element 22 and the second filter element 23 can be alternately used. When cleaning the sand remaining inside the first filter element 22, the second filter element 23 is started to perform the filtering work. Similarly, when cleaning the sand in the second filter element 23, the first filter element 22 is started to perform the filtering work. Without stopping the work of the entire oil circuit, the cleaning of the sand inside the first filter element 22 and the second filter element 23 is completed, reducing the cleaning time and thereby improving the oil transmission efficiency of the entire oil circuit.

[0043] In some embodiments, as Figure 2 and Figure 5As shown, the first filter element 22 includes a right-angle plate 221, a filter cartridge 222, a seal 223, a pressing member 224, and a fixing member 225. The right-angle plate 221 is sleeved in the mounting shell 21. The filter cartridge 222 is threadedly connected in the right-angle plate 221. The seal 223 is fixedly connected to the right-angle plate 221. The seal 223 is used to seal the mounting shell 21. The pressing member 224 is arranged in the right-angle plate 221. The pressing member 224 is used to close the bottom end of the oil inlet pipe 1. The pressing member 224 is connected to the right-angle plate 221 through the fixing member 225.

[0044] Further, the right-angle plate 221 can move horizontally in the mounting shell 21. The filter cartridge 222 is threadedly connected in the right-angle plate 221. The oil inlet pipe 1 penetrates through the mounting shell 21 and extends to the right-angle plate 221, and the oil inlet pipe 1 is communicated with the filter cartridge 222. By moving the seal 223, the right-angle plate 221 can be pulled out of the mounting shell 21. When the filter cartridge 222 is separated from the mounting shell 21 for replacement, the pressing member 224 seals the bottom of the oil inlet pipe 1. The fixing member 225 is mainly used to connect the pressing member 224 and the right-angle plate 221.

[0045] In some embodiments, such as Figure 1 and Figure 5 As shown, the seal 223 includes a seal plate 223a, a fixing pin 223b, and a guiding rod 223c. The seal plate 223a is fixedly connected to the right-angle plate 221. The seal plate 223a is connected to the mounting shell 21 through the fixing pin 223b. The guiding rod 223c is fixedly connected to the seal plate 223a. The guiding rod 223c is sleeved and connected to the mounting shell 21.

[0046] Further, the seal plate 223a can block the side wall of the mounting shell 21. The outer wall of the fixing pin 223b is processed with threads. The fixing pin 223b connects the seal plate 223a and the mounting shell 21. The seal plate 223a and the mounting shell 21 are arranged to be openable and closable. The guiding rod 223c is arranged such that the seal plate 223a can only move horizontally.

[0047] In some embodiments, such as Figure 4 As shown, the pressing member 224 includes a cylinder 224a, a top rod 224b, a rubber plate 224c, and an elastic member 224d. The cylinder 224a is mounted on the right-angle plate 221. The top rod 224b is sleeved in the cylinder 224a. The rubber plate 224c is fixedly connected to the top rod 224b. The elastic member 224d is arranged in the cylinder 224a.

[0048] Further, the ejector rod 224b can move up and down in the cylinder 224a. The rubber plate 224c is plastic, and an inclined surface is machined on the side of the rubber plate 224c close to the filter cartridge 222. As the right-angle plate 221 moves horizontally, when the rubber plate 224c contacts the bottom end of the oil inlet pipe 1, the rubber plate 224c first pushes the ejector rod 224b to move downward in the cylinder 224a and compresses the elastic member 224d. As the right-angle plate 221 moves horizontally, by the reset of the elastic member 224d, the rubber plate 224c gradually closes the bottom end of the oil inlet pipe 1.

[0049] In some embodiments, as Figure 2 and Figure 5 shown, the fixing member 225 includes a clamp 225a and a bolt 225b. The clamp 225a is fixedly connected to the cylinder 224a, and the clamp 225a is connected to the right-angle plate 221 through the bolt 225b.

[0050] Further, the clamp 225a is placed on the outer wall of the cylinder 224a, and the clamp 225a and the right-angle plate 221 are connected together through the bolt 225b, thereby fixing the use position of the cylinder 224a.

[0051] In some embodiments, as Figure 1 and Figure 3 shown, the second filter element 23 includes a flow guide member 231, a storage member 232, and a return pipe 233. The flow guide member 231 is used to guide the oil in the oil inlet pipe 1 into the second filter element 23. The storage member 232 is used to filter the sand and gravel in the oil in the flow guide member 231. The return pipe 233 guides the oil filtered by the storage member 232 into the oil outlet pipe 3.

[0052] Further, the second filter element 23 is installed on the oil inlet pipe 1 and the oil outlet pipe 3. The flow guide member 231 is used to change the flow direction of the oil in the oil path. The storage member 232 is mainly used to store the separated sand and gravel for later cleaning. The return pipe 233 is a telescopic hose, which is convenient to install. The oil after sand and gravel separation enters the liquid outlet pipe 3 through the return pipe 233 and is discharged.

[0053] In some embodiments, as Figure 3 shown, the flow guide member 231 includes a flow guide pipe 231a, a control valve 231b, and a connector 231c. The flow guide pipe 231a is communicated with the oil inlet pipe 1. The control valve 231b is installed in the flow guide pipe 231a. The connector 231c is installed on the flow guide pipe 231a, and the connector 231c is connected to the storage member 232.

[0054] Further, the diversion pipe 231a plays a role in diversion. The control valve 231b is used to control the opening and closing of the diversion pipe 231a. The connection head 231c is processed with threads for connecting to the storage part 232. When maintaining the first filter element 22, the diversion pipe 231a diverts the oil to the second filter element 23 for continuous filtration.

[0055] In some embodiments, as Figure 3 shown, the storage part 232 includes a housing 232a and a filter element 232b. The housing 232a is threadedly connected to the connection head 231c, and the filter element 232b is threadedly connected in the housing 232a.

[0056] Further, the housing 232a and the connection head 231c can be disassembled through threaded connection. The sand and gravel in the oil are retained between the housing 232a and the filter element 232b. By rotating the filter element 232b, it can be pulled out from the housing 232a.

[0057] In some embodiments, as Figure 1 and Figure 6 shown, an opening and closing assembly 4 is provided on the mounting shell 21. The opening and closing assembly 4 includes an end cover 41, a connecting member 42, and a rubber pad 43. The end cover 41 is installed on the mounting shell 21. The end cover 41 is connected to the mounting shell 21 through the connecting member 42, and the rubber pad 43 is fixedly connected to the end cover 41.

[0058] Further, the end cover 41 and the sealing plate 223a are symmetrically distributed on both sides of the mounting shell 21. The design of the connecting member 42 is mainly used for the connection between the end cover 41 and the mounting shell 21. The design of the rubber pad 43 increases the sealing between the end cover 41 and the mounting shell 21. The design of the connecting member 42 enables the end cover 41 and the mounting shell 21 to be in an openable and closable state, thereby facilitating the removal of the end cover 41 for cleaning the inside of the mounting shell 21.

[0059] In some embodiments, as Figure 1 and Figure 6 shown, the connecting member 42 includes a screw 421, a limiting plate 422, and a nut 423. The screw 421 is fixedly connected to the end cover 41, the limiting plate 422 is fixedly connected to the mounting shell 21, the limiting plate 422 is sleeved and connected to the screw 421, and the nut 423 is threadedly connected to the screw 421.

[0060] Further, the screws 421 are distributed on the upper and lower sides of the end cover 41. There are four screws 421 in total. The limiting plates 422 correspond to the screws 421. Two limiting plates 422 are fixed on the mounting shell 21, and the nut 423 is used to fix the position of the screw 421 in the limiting plate 422.

[0061] Working principle:

[0062] When the first filter element 22 is working properly, the oil fluid enters the installation shell 21 through the inlet pipe 1. Since the bottom end of the inlet pipe 1 abuts against the filter cartridge 222, after the oil fluid enters the filter cartridge 222 for filtration, the sand and gravel remain in the filter cartridge 222, and the filtered oil fluid gathers in the outlet pipe 3 at the bottom of the installation shell 21 and is discharged. When it is necessary to clean the sand and gravel in the filter cartridge 222, rotate the fixing pin 223b to separate it from the installation shell 21, and horizontally move the sealing plate 223a to drive the right-angle plate 221 to move in the installation shell 21. When the rubber plate 224c contacts the bottom end of the inlet pipe 1, the rubber plate 224c pushes the ejector rod 224b to move downward in the cylinder 224a and compresses the elastic member 224d. Utilizing the reset of the elastic member 224d, the rubber plate 224c seals the bottom end of the inlet pipe 1. At this time, it is necessary to open the control valve 231b to introduce the oil fluid into the second filter element 23. After the oil fluid is filtered by the filter element 232b, it enters the return pipe 233. The oil fluid enters the outlet pipe 3 through the return pipe 233, and then the filter cartridge 222 in the right-angle plate 221 can be replaced. Similarly, the replaced filter cartridge 222 is reinstalled in the installation shell 21, the rubber plate 224c separates from the bottom end of the inlet pipe 1, the filter cartridge 222 is communicated with the inlet pipe 1, the control valve 231b is closed, and the oil fluid re-enters the filter cartridge 222 for filtration. At this time, rotate the outer shell 232a to separate it from the connector 231, and clean the sand and gravel remaining between the outer shell 232a and the filter element 232b. When it is necessary to clean the inside of the installation shell 21, rotate the nut 423 to separate it from the screw 421, and then the end cover 41 can be removed from the installation shell 21 to maintain the installation shell 21.

[0063] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. An oil pipe anti-sand sediment isolation device, comprising an oil inlet pipe (1) and an oil outlet pipe (3), characterized in that: The oil pipe anti-sand sediment isolation device also includes: A sediment isolation component (2), wherein the sediment isolation component (2) collects and filters the oil sediment discharged from the oil inlet pipe (1); The sediment isolation assembly (2) comprises a mounting shell (21), a first filter element (22) and a second filter element (23); The mounting shell (21) is connected to the bottom of the oil inlet pipe (1), and the bottom of the mounting shell (21) is connected to the oil outlet pipe (3). The first filter element (22) is used to filter the oil entering the mounting shell (21). When the first filter element (22) is replaced, the second filter element (23) starts to work. The second filter element (23) is installed between the oil inlet pipe (1) and the oil outlet pipe (3). When the second filter element (23) is replaced, the first filter element (22) starts to work.

2. The oil pipe sand and sediment isolation device according to claim 1, characterized in that: The first filter element (22) comprises a right-angle plate (221), a filter cartridge (222), a sealing element (223), a fastening element (224) and a fixing element (225); The right-angle plate (221) is sleeved in the mounting shell (21), the filter cartridge (222) is threadedly connected to the right-angle plate (221), the sealing member (223) is fixedly connected to the right-angle plate (221), the sealing member (223) is used to seal the mounting shell (21), the fastening member (224) is arranged in the right-angle plate (221), the fastening member (224) is used to seal the bottom end of the oil inlet pipe (1), and the fastening member (224) is connected to the right-angle plate (221) via the fixing member (225).

3. The oil pipe sand and sediment isolation device according to claim 2, characterized in that: The sealing member (223) comprises a sealing plate (223a), a fixing pin (223b) and a guiding rod (223c); The sealing plate (223a) and the right-angle plate (221) are fixedly connected, the sealing plate (223a) is connected to the mounting shell (21) via the fixing pin (223b), the guiding rod (223c) is fixedly connected to the sealing plate (223a), and the guiding rod (223c) and the mounting shell (21) are sleeve-connected.

4. The oil pipe sand and sediment isolation device according to claim 2, characterized in that: The abutting member (224) comprises a cylinder (224a), a push rod (224b), a rubber plate (224c) and an elastic member (224d); The cylinder (224a) is mounted on the right-angle plate (221), the push rod (224b) is sleeved in the cylinder (224a), the rubber plate (224c) is fixedly connected to the push rod (224b), and the elastic member (224d) is arranged in the cylinder (224a).

5. The oil pipe sand and sediment isolation device according to claim 4, characterized in that: The fixing member (225) comprises a clamp (225a) and a bolt (225b); The clamp (225a) and the cylinder (224a) are fixedly connected, and the clamp (225a) is connected to the right-angle plate (221) via the bolt (225b).

6. The oil pipe sand and sediment isolation device according to claim 1, characterized in that: The second filter element (23) comprises a flow guide element (231), a storage element (232) and a return pipe (233); The guide member (231) is used to guide the oil in the oil inlet pipe (1) into the second filter member (23), the storage member (232) is used to filter the oil in the guide member (231) for sand and gravel, and the return pipe (233) guides the oil filtered by the storage member (232) into the oil outlet pipe (3).

7. The oil pipe sand and sediment isolation device according to claim 6, characterized in that: The flow guide member (231) comprises a flow guide pipe (231a), a control valve (231b) and a connector (231c); The flow guide pipe (231a) is connected to the oil inlet pipe (1), the control valve (231b) is installed in the flow guide pipe (231a), the connector (231c) is installed on the flow guide pipe (231a), and the connector (231c) is connected to the storage element (232).

8. The oil pipe sand and sediment isolation device according to claim 7, characterized in that: The storage element (232) includes a housing (232a) and a filter element (232b); The housing (232a) and the connector (231c) are threadedly connected, and the filter element (232b) is threadedly connected in the housing (232a).

9. The oil pipe sand and sediment isolation device according to claim 1, characterized in that: An opening and closing assembly (4) is provided on the mounting shell (21); The opening and closing assembly (4) comprises an end cover (41), a connecting piece (42) and a rubber pad (43); The end cover (41) is mounted on the mounting shell (21), the end cover (41) is connected to the mounting shell (21) via the connecting piece (42), and the rubber pad (43) is fixedly connected to the end cover (41).

10. The oil pipe sand and sediment isolation device according to claim 9, characterized in that: The connecting member (42) comprises a screw rod (421), a limiting plate (422) and a nut (423); The screw rod (421) is fixedly connected to the end cover (41), the limiting plate (422) is fixedly connected to the mounting shell (21), the limiting plate (422) and the screw rod (421) are sleeved and connected, and the nut (423) and the screw rod (421) are threadedly connected.

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