Cement pipe with continuous Venturi structure, its manufacturing mold and manufacturing method

Abstract

This application relates to the field of fluid transport pipeline technology, and proposes a cement pipe with a continuous Venturi structure, its manufacturing mold, and manufacturing method. The cement pipe with a continuous Venturi structure includes a pipe body, the inner wall of which is provided with multiple groove groups. The multiple groove groups are arranged at intervals along the circumference of the pipe body. Each groove group includes multiple grooves arranged at intervals along the axial direction of the pipe body. The grooves of each groove group are aligned in the axial direction of the pipe body. By providing multiple groove groups on the inner wall of the above-mentioned cement pipe, the inner cavity of the pipe body undergoes periodic contraction and expansion in the axial direction of the pipe body, forming a continuous Venturi structure. Utilizing the Venturi effect, the flow rate near the wall surface can be increased, thereby increasing the wall shear stress. This shear stress can remove dirt adhering to the wall surface and resuspend the dirt in the water flow for removal, thus achieving a self-cleaning effect and solving the problem of dirt easily adhering to the inner wall of cement pipes.

Description

Technical Field

[0001] This application relates to the field of fluid transport pipeline technology, and in particular to a cement pipe with a continuous Venturi structure and its manufacturing mold and manufacturing method. Background Technology

[0002] Currently, to avoid corrosion of metal pipes, sewage is usually discharged to designated locations through cement pipes. However, because the inner wall of cement pipes is relatively rough, it is easy for dirt (such as sludge, particulate matter, and biofilm) to adhere to the inner wall, which reduces the effective flow area of ​​the cement pipe and increases the transport resistance, thus affecting the transport of sewage. Summary of the Invention

[0003] In view of this, the present application provides a cement pipe with a continuous Venturi structure, a mold for manufacturing the same, and a manufacturing method thereof, to solve the problem of dirt easily adhering to the inner wall of the cement pipe.

[0004] The first aspect of this application proposes a cement pipe with a continuous Venturi structure, comprising a pipe body, wherein the inner wall of the pipe body is provided with a plurality of groove groups, the plurality of groove groups being arranged at intervals along the circumference of the pipe body, the groove group comprising a plurality of grooves arranged at intervals along the axial direction of the pipe body, and the grooves of each groove group being aligned in the axial direction of the pipe body.

[0005] The beneficial effects of the cement pipe with a continuous Venturi structure provided in this application embodiment are as follows: By providing multiple groove groups on the inner wall of the pipe body, the inner cavity of the pipe body has periodic contraction and expansion in the axial direction of the pipe body, forming a continuous Venturi structure. The Venturi effect can increase the flow rate near the wall surface, thereby increasing the shear stress on the wall surface. This shear stress can remove dirt attached to the wall surface and make the dirt resuspend in the water flow and be carried away, so as to achieve a self-cleaning effect and solve the problem of dirt easily adhering to the inner wall of cement pipes.

[0006] In some embodiments, the distance between two adjacent grooves in the groove group is equal to the axial dimension of the groove in the pipe body.

[0007] In some embodiments, the groove is a rectangular groove.

[0008] In some embodiments, the inner wall of the tube is coated with a superhydrophobic coating.

[0009] A second aspect of this application discloses a cement pipe manufacturing mold, comprising a tubular inner mold, a tubular outer mold, and a mandrel. The tubular inner mold includes a plurality of inner mold segments arranged circumferentially along the inner mold, and the tubular outer mold includes a plurality of outer mold segments arranged circumferentially along the outer mold. The outer surface of the tubular inner mold has a plurality of protrusions for forming a plurality of groove groups, the plurality of protrusion groups being spaced apart circumferentially along the inner mold, and each protrusion group including a plurality of protrusions spaced apart axially along the inner mold. The mandrel passes through the cavity of the tubular inner mold to support the inner mold.

[0010] In some embodiments, a portion of the plurality of inner mold lobes is a first mold lobe and a portion is a second mold lobe, the first mold lobe and the second mold lobe are arranged alternately and abutting each other; wherein, the cross-section of the first mold lobe is fan-shaped, and the outer end width of the cross-section of the second mold lobe is less than or equal to the inner end width of the cross-section of the second mold lobe.

[0011] In some embodiments, the mandrel is a tapered mandrel, and the cavity of the tubular inner mold is a tapered cavity adapted to the tapered mandrel.

[0012] The third aspect of this application discloses a method for manufacturing a cement pipe, which uses a cement pipe manufacturing mold as described in the second aspect, and includes the following steps: The cement-based slurry is injected into the forming cavity between the tubular outer mold and the tubular inner mold, and then vibrated to compact and initially solidify. Remove the tubular outer mold and the tubular inner mold to obtain a tube body with multiple groove groups.

[0013] In some embodiments, a superhydrophobic coating is applied to the inner wall of the pipe body, and the superhydrophobic coating is cured to form a cement pipe.

[0014] In some embodiments, before injecting the cement-based slurry between the tubular outer mold and the tubular inner mold, an anti-stick coating is applied to the inner surface of the tubular outer mold and the outer surface of the tubular inner mold.

[0015] In some embodiments, the cement-based slurry comprises 100 parts silicate cement, 195-205 parts standard sand, 34-36 parts water, 0.55-0.65 parts polycarboxylate superplasticizer, 0.025-0.035 parts hydroxypropyl methylcellulose, 1.9-2.1 parts hydrophobic silica powder, and 0.045-0.055 parts organosilicon defoamer.

[0016] In some embodiments, when adding polycarboxylate superplasticizer, the target water-cement ratio is first fixed, and then the fluidity is titrated to the target window by gradually adding polycarboxylate superplasticizer.

[0017] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the following are specific embodiments of this application. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or conventional technology will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of the structure of a cement pipe with a continuous Venturi structure provided in some embodiments of this application; Figure 2 yes Figure 1 The axially sectional view of a cement pipe with a continuous Venturi structure is shown. Figure 3 yes Figure 2 Enlarged view of point A in the middle; Figure 4 yes Figure 1 The cross-sectional view shown is a cement pipe with a continuous Venturi structure cut radially. Figure 5 yes Figure 4 Enlarged view of point B in the middle; Figure 6 This is an exploded view of a cement pipe manufacturing mold provided in some embodiments of this application; Figure 7 yes Figure 6 Enlarged view of point C in the middle; Figure 8 yes Figure 6 The right view of the tubular inner mold shown; Figure 9 This is a flowchart of a cement pipe manufacturing method provided in some embodiments of this application; Figure 10 This is a graph showing the deposition reduction rate of cement pipes with different fidelities as a function of flow rate, provided in some embodiments of this application. Figure 11 This is a graph showing the pressure drop of cement pipes with different fidelities as a function of flow rate, provided in some embodiments of this application. Figure 12 This is a high-fidelity stress distribution diagram of a cement pipe at a flow rate of 15 L / min provided in some embodiments of this application; Figure 13This is a stress distribution diagram of a common cement pipe with a flow rate of 15 L / min provided in some embodiments of this application; Figure 14 This is a high-fidelity stress distribution diagram of a cement pipe at a flow rate of 40 L / min provided in some embodiments of this application; Figure 15 This is a stress distribution diagram of a common cement pipe with a flow rate of 40 L / min provided in some embodiments of this application; Figure 16 This is a high-fidelity stress distribution diagram of a cement pipe at a flow rate of 50 L / min provided in some embodiments of this application; Figure 17 This is a stress distribution diagram of a common cement pipe with a flow rate of 50 L / min provided in some embodiments of this application.

[0020] The markings in the diagram mean: 10. Cement pipes; 11. Pipe body; 12. Trench group; 121. Trench; 20. Cement pipe making molds; 21. Tubular inner mold; 211. Inner mold flap; 2111. First mold flap; 2112. Second mold flap; 212. Protrusion group; 2121. Protrusion; 213. Cavity; 22. Tubular outer mold; 221. Outer mold flap; 222. First end plate; 23. Mandrel; 231. Second end plate; 232. Fixing screw. Detailed Implementation

[0021] The embodiments of the technical solution of this application will now be described in detail with reference to the accompanying drawings. These embodiments are only used to more clearly illustrate the technical solution of this application and are therefore merely examples, and should not be used to limit the scope of protection of this application.

[0022] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0023] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly defined.

[0024] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0025] In the description of the embodiments in this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0026] In the description of the embodiments of this application, the term "multiple" refers to two or more (including two), similarly, "multiple sets" refers to two or more (including two sets), and "multiple pieces" refers to two or more (including two pieces).

[0027] In the description of the embodiments of this application, the technical terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. They are only for the convenience of describing the embodiments of this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this application.

[0028] In the description of the embodiments of this application, unless otherwise expressly specified and limited, technical terms such as "installation," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. For those skilled in the art, the specific meaning of the above terms in the embodiments of this application can be understood according to the specific circumstances.

[0029] Currently, during long-term operation, municipal drainage pipes are prone to sludge, particulate matter deposition, and biofilm adhesion on their inner walls. This reduces the effective flow area of ​​the drainage pipes, increases transport resistance, and consequently significantly increases pumping energy consumption and maintenance costs. Traditional solutions involve periodic high-pressure flushing or chemical cleaning, which is a reactive, "remedial" maintenance approach that is costly and has limited effectiveness.

[0030] Among related technologies, there are microgrooves (micrometer-scale) designed on the surface of polymers to mimic shark skin, reducing turbulent frictional resistance. However, this approach has significant technological gaps in its application to cement pipes: First, the research aims to reduce fluid friction, and the effect of preventing the deposition of larger particles commonly found in drainage pipes has not been systematically studied and verified; second, achieving micrometer-scale precision geometry manufacturing on a traditional substrate like cement is itself an unsolved technical challenge.

[0031] Therefore, in order to solve the problem of dirt easily adhering to the inner wall of cement pipes, this application proposes a cement pipe with a continuous Venturi structure, as well as its manufacturing mold and manufacturing method.

[0032] The first aspect of this application proposes a cement pipe with a continuous Venturi structure for conveying sewage. Please refer to... Figure 1 The cement pipe 10 includes a pipe body 11. The inner wall of the pipe body 11 is provided with a plurality of groove groups 12. The plurality of groove groups 12 are arranged at intervals along the circumference of the pipe body 11. The groove group 12 includes a plurality of grooves 121 arranged at intervals along the axial direction of the pipe body 11. The grooves 121 of each groove group 12 are aligned in the axial direction of the pipe body 11.

[0033] Among them, the circumferential direction of the tube body 11 is Figure 1 In the X direction, the axial direction of tube 11 is Figure 1 in the Y direction.

[0034] For example, the inner cavity of the pipe body 11 is circular or nearly circular. The pipe body 11 is formed by casting and curing cement-based grout.

[0035] Understandably, two, three, four, five, six or more groove groups 12 can be arranged at intervals along the circumference of the pipe body 11; for example, twelve groove groups 12 are arranged at intervals along the circumference of the pipe body 11.

[0036] For example, any two adjacent groove groups 12 are equidistant, that is, multiple groove groups 12 are evenly spaced along the circumference of the pipe body 11. Of course, any two adjacent groove groups 12 may also be equidistant; or, some adjacent groove groups 12 may be equidistant, while others may be equidistant.

[0037] Understandably, the number of grooves 121 included in the groove group 12 can be set according to the axial length of the pipe body 11. Among them, the grooves 121 are millimeter-level grooves.

[0038] For example, any two adjacent grooves 121 in the groove group 12 are equidistant, that is, the multiple grooves 121 in the groove group 12 are evenly spaced along the axial direction of the pipe body 11. Of course, the distance between any two adjacent grooves 121 in the groove group 12 may also be different; or, some adjacent grooves 121 in the groove group 12 may be equidistant, while some adjacent grooves 121 may be equidistant.

[0039] The grooves 121 of each groove group 12 are aligned axially in the pipe body 11. Understandably, in the axial direction of the pipe body 11, the dimension of the inner cavity of the pipe body 11 at the groove 121 is larger than the dimension of the inner cavity of the pipe body 11 between the two grooves 121, causing the inner cavity of the pipe body 11 to exhibit periodic contraction and expansion in the axial direction of the pipe body 11. The dimensions of each groove 121 in each groove group 12 are identical.

[0040] The cement pipe 10 with a continuous Venturi structure provided in this application includes a pipe body 11. By providing multiple groove groups 12 on the inner wall of the pipe body 11, the inner cavity of the pipe body 11 periodically contracts and expands in the axial direction of the pipe body 11, forming a continuous Venturi structure. The Venturi effect can increase the flow rate near the wall, thereby increasing the shear stress on the wall. This shear stress can remove dirt attached to the wall and make the dirt resuspend in the water flow and be carried away, so as to achieve a self-cleaning effect and solve the problem that dirt easily adheres to the inner wall of the cement pipe 10.

[0041] Please refer to Figure 2 and Figure 3 In some embodiments, the distance t1 between two adjacent grooves 121 of the groove group 12 is equal to the axial dimension t2 of the groove 121 in the pipe body 11, that is, t1=t2.

[0042] For example, the groove 121 is rectangular, and the axial dimension t2 of the groove 121 in the pipe body 11 is the length of the groove 121.

[0043] For example, the distance t1 between two adjacent grooves 121 of the groove group 12 is 2 mm, and correspondingly, the axial dimension t2 of the groove 121 in the pipe body 11 is 2 mm.

[0044] The distance t1 between two adjacent grooves 121 of the groove group 12 provided in this application embodiment is equal to the axial dimension t2 of the groove 121 in the pipe body 11, which makes the periodic contraction and expansion of the inner cavity of the pipe body 11 in the axial direction of the pipe body 11 more regular, which is more conducive to increasing the near wall flow rate and increasing the wall shear stress, thereby better removing dirt attached to the wall.

[0045] In some other embodiments, the distance t1 between two adjacent grooves 121 of the groove group 12 may also be greater than or less than the axial dimension t2 of the groove 121 in the pipe body 11.

[0046] Please refer to Figures 3 to 5 In some embodiments, the groove 121 is a rectangular groove.

[0047] Wherein, the axial dimension t2 of the groove 121 in the pipe body 11 is the length of the groove 121, the circumferential dimension t3 of the groove 121 in the pipe body 11 is the width of the groove 121, and the radial dimension t4 of the groove 121 in the pipe body 11 is the height (i.e., depth) of the groove 121.

[0048] For example, the axial dimension t2 of the groove 121 in the pipe body 11 is 2 mm, the circumferential dimension t3 of the groove 121 in the pipe body 11 is 1 mm, and the radial dimension t4 of the groove 121 in the pipe body 11 is 0.5 mm.

[0049] In other embodiments, the groove 121 may also be of other shapes, such as an oval or elliptical groove.

[0050] In some embodiments, the inner wall of the tube 11 is coated with a superhydrophobic coating.

[0051] For example, a superhydrophobic coating can be uniformly coated on the inner wall of the pipe body 11 by spraying, dipping, brushing or other methods to obtain a superhydrophobic coating.

[0052] For example, the superhydrophobic coating can be a superhydrophobic coating containing hydrophobically modified nanoparticles.

[0053] The inner wall of the pipe body 11 provided in this application embodiment is coated with a superhydrophobic coating. Its hydrophobic properties can be used to reduce flow resistance, thereby reducing pressure loss, which is conducive to the removal of dirt by water flow and reduces the adhesion of dirt on the inner wall of the pipe body 11.

[0054] In some other embodiments, the inner wall of the tube 11 may not be coated with a superhydrophobic coating.

[0055] The cement pipe 10 with a continuous Venturi structure provided in this application embodiment can reduce the pressure drop to as low as 24.2% of that of ordinary cement pipes, achieving a drag reduction of up to 75.8%. Moreover, the drag reduction effect will be further improved after coating with a superhydrophobic coating.

[0056] Please refer to Figure 6 and Figure 7The second aspect of this application discloses a cement pipe manufacturing mold 20 for manufacturing a cement pipe 10 with a continuous Venturi structure as described in the first aspect. The cement pipe manufacturing mold 20 includes a tubular inner mold 21, a tubular outer mold 22, and a mandrel 23. The tubular inner mold 21 includes a plurality of inner mold segments 211 arranged circumferentially along the inner mold 21, and the tubular outer mold 22 includes a plurality of outer mold segments 221 arranged circumferentially along the outer mold 22. The outer surface of the tubular inner mold 21 has a plurality of protrusions 212 for forming a plurality of groove groups 12. The plurality of protrusion groups 212 are spaced apart circumferentially along the inner mold 21, and each protrusion group 212 includes a plurality of protrusions 2121 spaced apart axially along the inner mold 21. The mandrel 23 passes through the cavity 213 of the tubular inner mold 21 to support the inner mold 21.

[0057] The tubular outer mold 22 is located outside the tubular inner mold 21, that is, an annular molding cavity is formed between the tubular inner mold 21 and the tubular outer mold 22. After the cement-based slurry is injected into the molding cavity and solidified, the tube body 11 is obtained.

[0058] It should be noted that the tubular outer mold 22 is equipped with two first end plates 222. The first end plates 222 are annular structures. The axial length of the tubular outer mold 22 is less than the axial length of the tubular inner mold 21. The first end plates 222 are sleeved on the tubular inner mold 21 and abut against the end of the tubular outer mold 22 to close the molding cavity after the cement-based slurry is injected into the molding cavity. For example, the inner diameter of the first end plate 222 is the same as the outer diameter of the tubular inner mold 21, and the outer diameter of the first end plate 222 is the same as the outer diameter of the tubular outer mold 22.

[0059] Multiple inner mold segments 211 are arranged circumferentially along the tubular inner mold 21. That is, after the tube body 11 is formed in the forming cavity, the multiple inner mold segments 211 first move inward along the radial direction of the tube body 11, and then move along the axial direction of the tube body 11 to achieve separation of the tubular inner mold 21 from the tube body 11.

[0060] Understandably, the number of inner lobes 211 can be three, four, five, six, or more. For example, the number of inner lobes 211 is eight.

[0061] For example, multiple inner mold segments 211 can be obtained by wire cutting the tubular inner mold 21. Of course, the inner mold segments 211 can also be processed and assembled into a tubular inner mold 21.

[0062] Multiple outer mold segments 221 are arranged circumferentially along the tubular outer mold 22. That is, after the tube body 11 is formed in the forming cavity, the multiple outer mold segments 221 move outward radially along the tube body 11 to achieve separation of the tubular outer mold 22 from the tube body 11.

[0063] For example, there are two outer mold flaps 221. Of course, the number of outer mold flaps 221 can also be three, four, five or more.

[0064] For example, multiple outer mold segments 221 can be obtained by wire cutting the tubular outer mold 22. Of course, the outer mold segments 221 can also be processed and assembled into a tubular outer mold 22.

[0065] Understandably, two, three, four, five, six, or more protrusion groups 212 can be arranged at intervals along the circumference of the tubular inner mold 21. It should be noted that multiple protrusion groups 212 are used to form multiple groove groups 12, therefore, the number of protrusion groups 212 is the same as the number of groove groups 12; for example, twelve groove groups 12 are arranged at intervals along the circumference of the tube body 11, and correspondingly, twelve protrusion groups 212 are arranged at intervals along the circumference of the tubular inner mold 21.

[0066] For example, protrusion 2121 is a rectangular protrusion.

[0067] Understandably, the number of protrusions 2121 included in the protrusion group 212 can be set according to the axial length of the tubular inner mold 21. It should be noted that since the protrusions 2121 are used to form the grooves 121, the number of protrusions 2121 in the protrusion group 212 is the same as the number of grooves 121 in the groove group 12.

[0068] The mandrel 23 is inserted into the cavity 213 of the tubular inner mold 21 to support the tubular inner mold 21 and ensure molding accuracy. It should be noted that the mandrel 23 and the tubular inner mold 21 are basically the same length. The mandrel 23 is equipped with two second end plates 231 and two fixing screws 232. The two ends of the mandrel 23 are respectively provided with threaded holes, and the second end plates 231 have screw through holes. After the mandrel 23 is inserted into the cavity 213 of the tubular inner mold 21, the two fixing screws 232 fix the two second end plates 231 to the mandrel 23 to clamp the tubular inner mold 21.

[0069] Please refer to Figure 6 and Figure 8 In some embodiments, a portion of the plurality of inner mold lobes 211 is a first mold lobe 2111 and a portion is a second mold lobe 2112, with the first mold lobe 2111 and the second mold lobe 2112 arranged alternately and abutting each other; wherein, the cross-section of the first mold lobe 2111 is fan-shaped, and the outer end width t5 of the cross-section of the second mold lobe 2112 is less than or equal to the inner end width t6 of the cross-section of the second mold lobe 2112.

[0070] For example, eight inner lobes 211 are provided, four of which are first lobes 2111 and the other four are second lobes 2112. Of course, there may also be four inner lobes 211, two of which are first lobes 2111 and the other two are second lobes 2112; or, there may be six inner lobes 211, three of which are first lobes 2111 and the other three are second lobes 2112.

[0071] The cross section of the first mold lobe 2111 refers to the cross section of the first mold lobe 2111 after being radially cut along the tubular inner mold 21; the cross section of the second mold lobe 2112 refers to the cross section of the second mold lobe 2112 after being radially cut along the tubular inner mold 21.

[0072] Based on the above technical solution, since the outer width t5 of the cross-section of the second mold segment 2112 is less than or equal to the inner width t6 of the cross-section of the second mold segment 2112, after the tube body 11 is formed, multiple second mold segments 2112 can be moved radially inward along the inner tubular mold 21, and then multiple first mold segments 2111 can be moved radially inward along the inner tubular mold 21 to separate the inner tubular mold 21 from the tube body 11 without damaging the tube body 11. Moreover, the first mold segments 2111 and the second mold segments 2112 are arranged in a face-to-face contact manner, which can ensure the stability of the inner tubular mold 21 during the forming of the tube body 11, thereby ensuring the forming accuracy of the tube body 11.

[0073] In some other embodiments, the cross-sections of the multiple inner mold segments 211 can all be fan-shaped. In this case, two adjacent inner mold segments 211 are in point-to-point contact, and a triangular notch is formed at the contact point to achieve demolding without damage.

[0074] In some embodiments, the mandrel 23 is a tapered mandrel, and the cavity 213 of the tubular inner mold 21 is a tapered cavity adapted to the tapered mandrel. Please refer to... Figure 6 The diameter of the left end of the mandrel 23 is smaller than the diameter of the right end of the mandrel 23, and the diameter of the left end of the cavity 213 is smaller than the diameter of the right end of the cavity 213. This facilitates the extraction of the mandrel 23 from the tubular inner mold 21.

[0075] The third aspect of this application discloses a method for manufacturing a cement pipe 10 having a continuous Venturi structure. This method utilizes a cement pipe manufacturing mold 20 as described in the second aspect. Please refer to... Figure 9 This includes the following steps: S100. Inject cement-based slurry into the forming cavity between the tubular outer mold 22 and the tubular inner mold 21, vibrate to compact and initially solidify.

[0076] The cement-based slurry is a highly fluid cement-based slurry to improve the molding accuracy of the groove 121.

[0077] For example, the molding cavity between the tubular outer mold 22 and the tubular inner mold 21 is an annular cavity.

[0078] For example, the vibrating table vibrates for 2 minutes (50 Hz, 0.8 mm amplitude) to compact the cement-based slurry.

[0079] S200, Remove the tubular outer mold 22 and tubular inner mold 21 to obtain a pipe body 11 with multiple groove groups 12, and continue to cure it to the specified age.

[0080] For example, the tubular outer mold 22 can be removed first, and then the tubular inner mold 21 can be removed.

[0081] For example, curing is carried out in a standard curing room (temperature 20±2℃, relative humidity ≥95%) for 7 days.

[0082] In some embodiments, a superhydrophobic coating is applied to the inner wall of the pipe body 11, and after the superhydrophobic coating is cured, a cement pipe 10 with a continuous Venturi structure is formed.

[0083] Optionally, the inner wall of the tube 11 may be dried and dust-removed before the superhydrophobic coating is applied to the inner wall of the tube 11.

[0084] Understandably, a superhydrophobic coating (such as a superhydrophobic coating containing hydrophobic modified nanoparticles) can be uniformly coated on the inner wall of the pipe body 11 by spraying, dipping, or brushing to obtain a superhydrophobic coating; then, the superhydrophobic coating is thermo-cured or naturally cured to obtain a cement pipe 10 with a continuous Venturi structure.

[0085] Based on the above technical solution, the hydrophobic properties of the superhydrophobic coating can be used to reduce flow resistance, thereby reducing pressure loss, which is conducive to the removal of dirt by water flow and reduces the adhesion of dirt on the inner wall of the pipe body 11.

[0086] In some embodiments, before the cement-based slurry is injected between the tubular outer mold 22 and the tubular inner mold 21, an anti-stick coating is applied to the inner surface of the tubular outer mold 22 and the outer surface of the tubular inner mold 21 to facilitate demolding. For example, the anti-stick coating may be a polytetrafluoroethylene coating.

[0087] In some embodiments, the cement-based slurry comprises 100 parts silicate cement, 195-205 parts standard sand, 34-36 parts water, 0.55-0.65 parts polycarboxylate superplasticizer, 0.025-0.035 parts hydroxypropyl methylcellulose, 1.9-2.1 parts hydrophobic silica powder, and 0.045-0.055 parts organosilicon defoamer.

[0088] Silicate cement is the basic cementitious material.

[0089] Standard sand is fine aggregate, screened, with a maximum particle size D. max ≤0.45mm, to prevent clogging. For example, 200 parts of standard sand.

[0090] Water is used as the mixing medium. For example, 35 parts of water are used, that is, the water-cement ratio is 0.35.

[0091] Polycarboxylate superplasticizers enable high fluidity (fluidity greater than or equal to 180 mm) at low water-cement ratios; for example, 0.6 parts of polycarboxylate superplasticizer, i.e., 0.6 wt% of cement mass.

[0092] The role of hydroxypropyl methylcellulose is to instantly lock the microstructure framework when the slurry is left to stand; for example, 0.03 parts of hydroxypropyl methylcellulose.

[0093] Hydrophobic silica powder can improve the hydrophobicity of the interface and reduce surface defects; for example, 2.0 parts of hydrophobic silica powder.

[0094] Silicone defoamers can eliminate microbubbles and prevent the formation of "pockmark" defects on the surface of microstructures; for example, 0.05 parts of silicone defoamer.

[0095] Experiments have verified that with a water-cement ratio of 0.35 and a polycarboxylate superplasticizer dosage of 0.6wt%, the fluidity can be stably maintained at 185±5mm, thus enabling the cement-based slurry to prepare sub-millimeter (≤0.5mm) microstructures.

[0096] In some embodiments, when adding polycarboxylate superplasticizer, the target water-cement ratio is first fixed, and then the fluidity is titrated to the target window by gradually adding polycarboxylate superplasticizer.

[0097] Taking a water-cement ratio of 0.35 as an example: The initial dosage of polycarboxylate superplasticizer was 0.4 wt%, and the measured flowability was 160 mm (less than 160 mm). Increase the polycarboxylate superplasticizer to 0.5wt%, the flowability is 175mm (still insufficient); Increase polycarboxylate superplasticizer to 0.6wt%, flowability 185mm (meets the standard, entering the target window of 180–190mm); The optimal dosage of polycarboxylate superplasticizer at this water-cement ratio was finally determined to be 0.6 wt%.

[0098] The above method transforms fluidity from an uncertain "result" into a precisely controllable "constraint," decoupling the relationship between water-cement ratio and fluidity, and enabling the rapid determination of the optimal polycarboxylate superplasticizer dosage under any water-cement ratio.

[0099] It has achieved standardization and platformization of formula design, providing a unified formula determination method for microstructure components with different strength requirements.

[0100] The method for preparing the cement-based slurry provided in this application embodiment is as follows: Weigh the raw materials: 333g cement, 666g standard sand, 117g water, 2g polycarboxylate superplasticizer, 0.1g hydroxypropyl methylcellulose, 6.7g hydrophobic silica powder, and 0.17g organosilicon defoamer.

[0101] The polycarboxylate superplasticizer was pre-dissolved in water and stirred for 30 seconds to form a homogeneous solution; Premix cement, standard sand, hydroxypropyl methylcellulose, and hydrophobic silica powder dry materials for 1 minute; Pour the aqueous solution containing polycarboxylate superplasticizer into the dry material at once, stir at low speed for 2 minutes, and then stir at high speed for 3 minutes. Add the silicone defoamer in the last 10 seconds and continue stirring until homogeneous to obtain the cement-based slurry.

[0102] The fidelity of the trench 121 provided in this embodiment is evaluated by the percentage of the measured depth of the trench 121 to the designed depth. The fidelity of the trench 121 is crucial for the self-cleaning of the cement pipe 10. The aforementioned cement-based slurry has good fluidity and shape retention, possessing excellent instantaneous self-flowing filling capability, and can smoothly and uniformly fill every corner of the microstructure, thereby improving the fidelity of the trench 121. Specifically, a percentage of measured depth to designed depth ≥ 90% is considered high fidelity, while a percentage < 90% is considered low fidelity.

[0103] Please refer to Figure 10 At low flow rates (10-20 L / min) and high flow rates (30-50 L / min), the deposition reduction rate of the cement pipe 10 with high-fidelity groove 121 is greater than that of the cement pipe 10 with low-fidelity groove 121. That is, the cement pipe 10 with high-fidelity groove 121 has better anti-deposition performance.

[0104] The low flow rate (10-20 L / min) and high flow rate (30-50 L / min) were separated at a flow rate of 25 L / min. At the low flow rate (10-20 L / min), the cement pipe 10 with high-fidelity grooves 121 operates in a vortex-driven mode, where Taylor vortices act as a microscopic "broom," increasing wall shear stress. At the high flow rate (30-50 L / min), the cement pipe 10 with high-fidelity grooves 121 operates in a turbulence-driven mode, with the grooves 121 acting as turbulence enhancers, significantly increasing wall shear stress. Thus, wall deposition can be effectively reduced at both low and high flow rates.

[0105] Please refer to Figure 11Within the tested flow range, the pressure drop of the cement pipe 10 with high-fidelity grooves 121 was lower than that of the ordinary cement pipe; moreover, except at a flow rate of 15 L / min, the pressure drop of the cement pipe 10 with high-fidelity grooves 121 was lower than that of the cement pipe 10 with low-fidelity grooves 121. The pressure drop of the cement pipe 10 with low-fidelity grooves 121 was higher than that of the ordinary cement pipe at certain flow rates (10 L / min and 40 L / min). In other words, the cement pipe 10 with high-fidelity grooves 121 exhibits better drag reduction.

[0106] Please refer to Figure 12 and Figure 13 At a flow rate of 15 L / min, the average wall shear stress of the cement pipe 10 with high-fidelity groove 121 is greater than that of an ordinary cement pipe; please refer to Figure 14 and Figure 15 At a flow rate of 40 L / min, the average wall shear stress of the cement pipe 10 with high-fidelity groove 121 is greater than that of an ordinary cement pipe; please refer to Figure 16 and Figure 17 At a flow rate of 50 L / min, the average wall shear stress of the cement pipe 10 with high-fidelity grooves 121 is greater than that of an ordinary cement pipe. Therefore, compared to an ordinary cement pipe, the average wall shear stress of the cement pipe 10 with high-fidelity grooves 121 is increased, for example, by 1.48 to 1.74 times, which facilitates the removal of dirt adhering to the wall surface and achieves a self-cleaning effect.

[0107] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A cement pipe manufacturing mold, characterized in that, For manufacturing cement pipes with a continuous Venturi structure, the cement pipe includes a pipe body, the inner wall of which is provided with multiple sets of grooves. These sets of grooves are spaced apart circumferentially along the pipe body. Each set of grooves includes multiple grooves spaced apart axially along the pipe body. The grooves in each set of grooves are aligned axially along the pipe body, so that the inner cavity of the pipe body experiences periodic contraction and expansion axially, forming a continuous Venturi structure and increasing wall shear stress. The distance between two adjacent grooves in a set of grooves is equal to the axial dimension of the groove in the pipe body, and the grooves are rectangular. The cement pipe manufacturing mold includes a tubular inner mold, a tubular outer mold, and a mandrel. The tubular inner mold includes multiple inner mold segments arranged circumferentially along the inner mold, and the tubular outer mold includes multiple outer mold segments arranged circumferentially along the outer mold. The outer surface of the tubular inner mold has multiple protrusions for forming multiple groove groups. The multiple protrusion groups are spaced apart circumferentially along the inner mold, and each protrusion group includes multiple protrusions spaced apart axially along the inner mold. The mandrel passes through the cavity of the tubular inner mold to support the inner mold.

2. The cement pipe manufacturing mold as described in claim 1, characterized in that, A portion of the plurality of inner mold lobes is a first mold lobe and a portion is a second mold lobe, the first mold lobe and the second mold lobe are arranged alternately and abutting each other; wherein, the cross-section of the first mold lobe is fan-shaped, and the outer end width of the cross-section of the second mold lobe is less than or equal to the inner end width of the cross-section of the second mold lobe.

3. The cement pipe manufacturing mold as described in claim 1, characterized in that, The mandrel is a tapered mandrel, and the cavity of the tubular inner mold is a tapered cavity adapted to the tapered mandrel.

4. A method for manufacturing cement pipes, characterized in that, Making a mold using a cement pipe as described in any one of claims 1-3 includes the following steps: The cement-based slurry is injected into the forming cavity between the tubular outer mold and the tubular inner mold, and then vibrated to compact and initially solidify. Remove the tubular outer mold and the tubular inner mold to obtain a tube body with multiple groove groups.

5. The method for manufacturing cement pipes as described in claim 4, characterized in that, A superhydrophobic coating is applied to the inner wall of the pipe, and the superhydrophobic coating is cured to form a cement pipe.

6. The method for manufacturing cement pipes as described in claim 4, characterized in that, The cement-based slurry comprises 100 parts silicate cement, 195-205 parts standard sand, 34-36 parts water, 0.55-0.65 parts polycarboxylate high-efficiency water-reducing agent, 0.025-0.035 parts hydroxypropyl methylcellulose, 1.9-2.1 parts hydrophobic silica powder, and 0.045-0.055 parts organosilicon defoamer.

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