Composite foamed material filled hollow spiral drainage pipe and manufacturing method thereof

Abstract

The present application relates to the technical field of drainage pipe, in particular to a kind of composite foamed material filling hollow spiral drainage pipeline and its manufacturing method, drainage pipeline includes outer layer pipe and at least one inner layer pipe being sequentially arranged from outside to inside, outer layer pipe and inner layer pipe, inner layer pipe and inner layer pipe are connected by connecting piece, spiral rib is arranged on the inner wall of inner layer pipe located in the innermost side, sound-absorbing layer is arranged between outer layer pipe and the inner layer pipe, inner layer pipe, sound-absorbing layer is filled with foamed material expansion, foamed material includes the following composition according to weight percentage: polyurethane prepolymer 40~60%, rubber particle 20~40%, steel slag 20~35%.The present application is combined by spiral flow guide structure and hollow foamed material, realizes broadband high-efficiency noise reduction, makes plastic drainage pipe noise value reach 33 dB.Drainage pipeline design is reasonable, simple structure, low in cost, can effectively play the role of sound insulation and noise reduction.

Description

Technical Field

[0001] This invention relates to the field of drainage pipe technology, and in particular to a hollow spiral drainage pipe filled with composite foam material and its manufacturing method. Background Technology

[0002] According to the latest GB 55038-2025 "Residential Project Specification", the noise level of adjacent bedrooms during bathroom drainage should be ≤33dB. However, existing products on the market, such as ordinary PVC-U pipes, have a noise level of 58dB, while spiral noise-reducing pipes and core-layer foamed noise-reducing pipes have noise levels of 48-53dB, all of which fail to meet the standard. Even the best products on the market, such as super-quiet pipes (45dB) and HDPE pipes (46.5dB), still exceed the standard by more than 37%. Existing noise-reducing pipes using a single noise reduction method (such as spiral rib design and core-layer foaming) only reduce noise by 5-10dB. Although the spiral rib structure design can effectively reduce mid-to-high frequency noise, it can also highlight or even exacerbate low-frequency noise. The foamed material in core-layer foamed noise-reducing pipes absorbs sound but lacks rigidity and surface density, and there is a contradiction between material density and sound insulation, resulting in the inability to meet the noise level requirements for drainage pipes.

[0003] Therefore, a new noise-reducing drainage pipe needs to be designed. Summary of the Invention

[0004] The purpose of this invention is to solve the problem that the noise level of existing plastic drainage pipes is greater than 33 dB, which fails to meet the noise level requirements for drainage pipes, and to provide a composite foamed material-filled hollow spiral drainage pipe and its manufacturing method.

[0005] In a first aspect, the present invention provides a composite foamed material-filled hollow spiral drainage pipe, comprising an outer layer pipe and at least one inner layer pipe arranged sequentially from the outside to the inside, wherein the outer layer pipe and the inner layer pipe, and the inner layer pipe and the inner layer pipe are connected by connectors, and a spiral rib is provided on the inner wall of the innermost inner layer pipe, wherein a sound-absorbing layer is provided between the outer layer pipe and the inner layer pipe, and between the inner layer pipe and the inner layer pipe, and the sound-absorbing layer is filled with expanded foamed material, wherein the foamed material comprises the following components by weight percentage: 40-60% polyurethane prepolymer, 20-40% rubber particles, and 20-35% steel slag.

[0006] Through the above technical solutions, the drainage pipe structure achieves noise control through material innovation and structural optimization. Spiral ribs are installed on the innermost inner wall of the innermost pipe. During drainage, the spiral ribs cause the water to flow tangentially downwards, reducing vertical impact and lowering noise by 8-10 dB. This further reduces noise caused by the disordered flow of water impacting the drainage pipe. The hollow layer between the inner and outer pipes, or between inner pipes themselves, serves as a sound-absorbing layer, filled with expanded foam material. The sound-absorbing layer structure is similar to a sponge structure, which absorbs the noise generated by water flowing through the drainage pipe. Combined with the porous structure's sound absorption and damping vibration reduction, this achieves noise reduction, further improving the drainage pipe's sound insulation performance. The foam material consists of 40-60% polyurethane prepolymer, 20-40% rubber particles, and 20-35% steel slag, possessing good rigidity, enabling the drainage pipe to meet noise level requirements.

[0007] In a preferred embodiment of the present invention, both the outer tube and the inner tube are tubular, and the cross-sections of the outer tube and the inner tube are circular, elliptical, square, or rectangular. Preferably, the cross-sections of the outer tube and the inner tube are circular.

[0008] As a preferred embodiment of the present invention, the drainage pipe adopts a two-layer structure design, including the outer pipe and the inner pipe.

[0009] As a preferred embodiment of the present invention, the drainage pipe adopts a three-layer structure design, including the outermost outer layer pipe, the middle inner layer pipe, and the innermost inner layer pipe. The connectors include a first connector and a second connector. The outermost outer layer pipe and the middle inner layer pipe are connected at intervals by the first connector, and the middle inner layer pipe and the innermost inner layer pipe are connected at intervals by the second connector. The first connector and the second connector are staggered.

[0010] In a preferred embodiment of the present invention, the spiral ribs are threaded on the innermost inner wall of the innermost pipe, and the pitch of the spiral ribs is 1.1 to 1.2 times the diameter of the innermost inner pipe. The spiral ribs are arranged in a spiral shape with the same curvature along the length of the drainage pipe on the innermost inner wall. By setting the threaded spiral ribs, not only can the water flow be effectively buffered, but the buffered water flow can also slide smoothly down, thereby avoiding large impact noise during the buffering process. The pitch of the spiral ribs is a key factor affecting the sound insulation and noise reduction effect of the drainage pipe. Controlling the pitch of the spiral ribs to 1.1 to 1.2 times the diameter of the innermost inner pipe is crucial; if the pitch of the spiral ribs becomes smaller or larger, the noise reduction effect will be worse.

[0011] In a preferred embodiment of the present invention, the connector, the inner tube, and the outer tube are integrally formed. This integral structure of the connector, inner tube, and outer tube makes the drainage pipe more stable and extends its service life.

[0012] In a preferred embodiment of the present invention, the connectors are uniformly disposed between the inner layer pipe and the outer layer pipe or between the inner layer pipes along the length of the drainage pipe; 3 to 8 connectors are disposed along the radial direction of the drainage pipe. The number of connectors is a key factor affecting the sound insulation and noise reduction effect of the drainage pipe. If there are fewer than 3 connectors, it is impossible to improve the structural strength of the drainage pipe; if there are more than 8 connectors, the sound insulation performance deteriorates due to the "sound bridge" effect, and the noise reduction effect of the drainage pipe structure becomes worse. Therefore, the number of connectors is controlled to be 3 to 8.

[0013] As a preferred embodiment of the present invention, the density of the foaming material is 1800~2500 kg / m³. 3 .

[0014] As a preferred embodiment of the present invention, the foaming material comprises the following components by weight percentage: 40-50% polyurethane prepolymer, 25-35% rubber particles, and 30-35% steel slag.

[0015] As a preferred embodiment of the present invention, the steel slag has a mesh size of 5 to 20 mesh.

[0016] As a preferred embodiment of the present invention, the inner tube and the outer tube have the same thickness.

[0017] In a preferred embodiment of the present invention, the thickness of the sound-absorbing layer is 20-30% of the total thickness of the inner and outer tubes. The thickness of the sound-absorbing layer is a key factor affecting the sound insulation and noise reduction effect of drainage pipes. The pipe structure is a classic double-layer sound insulation model (conforming to the "mass-spring-mass" law). If the thickness of the sound-absorbing layer is less than 20% of the total thickness, the "spring" effect is weak, and the sound insulation performance will be significantly reduced, especially near the resonant frequency. Its acoustic performance may become mediocre, failing to fully utilize the advantages of the drainage pipe structure and making it difficult to stably control noise below 33dB, particularly for low-frequency impact noise. If the sound-absorbing layer is too thick, it will lead to an excessively large aspect ratio of the connectors, reducing their resistance to lateral shear and stability. Under external pressure, the connectors may buckle, reducing the overall pressure-bearing capacity of the pipe. While excessive thickness is beneficial for sound insulation, it sacrifices the product's mechanical strength and durability, potentially leading to failure to pass relevant pipe product mechanical testing standards (such as ring stiffness and impact resistance tests). Therefore, in this invention, the thickness of the sound-absorbing layer is 20-30% of the total thickness of the inner and outer tubes, which can significantly improve the sound absorption coefficient and sound insulation in the mid-to-low frequency range.

[0018] As a preferred embodiment of the present invention, the outer tube and the inner tube are made of polyvinyl chloride or polyethylene material.

[0019] Secondly, the present invention provides a method for manufacturing a hollow spiral drainage pipe filled with composite foam material, comprising the following steps:

[0020] S1. Add the plastic material to the screw extruder;

[0021] S2. Connect the extrusion molding die corresponding to the drainage pipe structure to the screw extruder, and extrude to obtain a pipe including the inner tube, the outer tube, and the connector. Simultaneously mold the spiral ribs during the extrusion process.

[0022] S3. The pre-mixed foaming material is injected into the sound-absorbing layer using a high-pressure injection process to obtain the drainage pipe; the sound-absorbing layer is first injected between the outer tube and the inner tube; if a sound-absorbing layer is provided between the inner tubes, the foaming material is then injected into the sound-absorbing layer between the inner tubes.

[0023] In the above technical solution, the inner tube, outer tube and connector are co-extruded, and the inner tube, outer tube and connector are extruded in one go by an extruder. Then, a high-pressure injection process is used to inject foam material into the hollow layer of the extruded tube to form a sound-absorbing layer.

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0025] 1. This invention provides a composite foamed material-filled hollow spiral drainage pipe. The drainage pipe adopts a spiral flow guide + hollow foamed material. The spiral flow guide can reduce water flow impact, and the hollow foamed material filling sound-absorbing layer can combine sound absorption and damping functions. Through the combination of structural and material innovation, the noise reduction pipe material can more effectively achieve wide-frequency (high, medium, low) high-efficiency noise reduction. It achieves breakthroughs in three dimensions: noise reduction performance, cost control, and construction efficiency, and provides a technical solution for solving residential drainage noise pollution that has both engineering practicality and industrialization prospects.

[0026] 2. This invention provides a composite foamed material-filled hollow spiral drainage pipe. Through broadband high-efficiency noise reduction, the noise level of the plastic drainage pipe is less than 33 dB, which meets the specifications of residential projects. Test data shows that its comprehensive performance is significantly better than similar products at home and abroad, and it has significant competitive advantages and market value. The drainage pipe is reasonably designed, simple in structure, low in cost, and can effectively play a role in sound insulation and noise reduction. Attached Figure Description

[0027] Figure 1This is a cross-sectional view of the hollow spiral drainage pipe filled with composite foam material in Example 1;

[0028] Figure 2 This is a schematic diagram of the inner wall of the inner layer pipe in the drainage pipe of Example 1;

[0029] Figure 3 This is a cross-sectional view of the hollow spiral drainage pipe filled with composite foam material in Example 7;

[0030] Marked in the image:

[0031] 1-Outer tube, 2-Inner tube, 3-Connector, 4-Spiral rib, 5-Sound absorbing layer. Detailed Implementation

[0032] The present invention will now be described in further detail with reference to specific embodiments. However, this should not be construed as limiting the scope of the present invention to the following embodiments; all technologies implemented based on the content of the present invention fall within the scope of the present invention.

[0033] The raw materials used in the following examples are as follows: polyurethane prepolymer was provided by Chengdu Liheng Polyurethane New Material Co., Ltd.; rubber granules were purchased from Lingshou County Baixin New Material Technology Co., Ltd., 100 mesh; steel slag was purchased from Lingshou County Mineral Products Processing Co., Ltd., 5-20 mesh.

[0034] Example 1

[0035] This embodiment provides a composite foamed material-filled hollow spiral drainage pipe. The drainage pipe adopts a two-layer structure design, such as... Figure 1 , Figure 2 It includes an outer tube 1 and an inner tube 2 arranged sequentially from the outside to the inside. The outer tube 1 and the inner tube 2 are connected by a connector 3. The connector 3 is evenly arranged between the inner tube 2 and the outer tube 1 along the length of the drainage pipe. There are 3 connectors arranged along the radial direction of the drainage pipe. The connector 3 is integrally formed with the inner tube 2 and the outer tube 1. The inner wall of the innermost inner tube 2 is provided with a spiral rib 4. The spiral rib 4 is threaded on the inner wall of the inner tube 2. The diameter of the inner tube 2 is Φ151mm and the pitch between the spiral ribs 4 is 181mm.

[0036] A sound-absorbing layer 5 is installed between the outer tube 1 and the inner tube 2. The sound-absorbing layer 5 is filled with expanded foam material, which, by weight percentage, comprises the following: 40% polyurethane prepolymer, 30% rubber granules, and 30% steel slag. The rubber granules have a particle size of 100 mesh, and the steel slag has a mesh size of 10-20 mesh. Both the outer and inner tubes are tubular with circular cross-sections. The outer diameter of the drainage pipe is 160 mm, and its thickness is 4.5 mm. The inner tube has a thickness of 1.8 mm, the outer tube has a thickness of 1.8 mm, and the sound-absorbing layer has a thickness of 0.9 mm, which is 25% of the total thickness of the inner and outer tubes.

[0037] The method for manufacturing drainage pipes includes the following steps:

[0038] S1. Add the plastic material to the twin-screw extruder;

[0039] S2. According to the structure of the drainage pipe, connect the corresponding extrusion molding die to the twin-screw extruder, and extrude to obtain a pipe including an inner tube, an outer tube, and connectors. During the extrusion process, the spiral ribs are molded simultaneously.

[0040] S3. The pre-mixed foam material is injected into the sound-absorbing layer between the outer and inner tubes using a high-pressure injection process; if a sound-absorbing layer is provided between the inner tubes, the foam material is then injected into the sound-absorbing layer between the inner tubes, and the drainage pipe is obtained after the foam material has cured.

[0041] In the manufacturing process, sanitary-grade polyvinyl chloride (PVC) resin is used as the main raw material, with stabilizers, lubricants, and colorants added to produce the pipes. A twin-screw extruder is used, with the following extrusion temperatures: feeding section 190~200℃, compression section 180~190℃, plasticizing section 170~180℃, and homogenization section 160~170℃; the extrusion die temperature is 190~200℃. The foamed material is produced using a high-pressure injection molding process, with the number of injection heads determined based on actual pipe requirements. The expanded density of the foamed material is 2000 kg / m³. 3 .

[0042] Example 2

[0043] This embodiment provides a composite foamed material-filled hollow spiral drainage pipe. The drainage pipe adopts a two-layer structure design, including an outer pipe and an inner pipe arranged sequentially from the outside to the inside. The outer pipe and the inner pipe are connected by connectors. The connectors are evenly arranged between the inner pipe and the outer pipe along the length of the drainage pipe. There are 8 connectors arranged along the radial direction of the drainage pipe. The connectors are integrally formed with the inner pipe and the outer pipe. Spiral ribs are provided on the inner wall of the innermost inner pipe. The spiral ribs are threaded on the inner wall of the inner pipe. The inner pipe is Φ151mm, and the pitch between the spiral ribs is 181mm.

[0044] A sound-absorbing layer is installed between the outer and inner pipes. This layer is filled with expanded foam material, which, by weight percentage, comprises: 40% polyurethane prepolymer, 30% rubber granules, and 30% steel slag. The rubber granules have a particle size of 100 mesh, and the steel slag has a mesh size of 10-20 mesh. Both the outer and inner pipes are tubular with circular cross-sections. The outer diameter of the drainage pipe is 160 mm, and its thickness is 4.5 mm. The inner pipe has a thickness of 1.8 mm, the outer pipe has a thickness of 1.8 mm, and the sound-absorbing layer has a thickness of 0.9 mm.

[0045] The drainage pipes were manufactured using the method described in Example 1, and the density of the expanded foam material was 2000 kg / m³. 3 .

[0046] Example 3

[0047] This embodiment provides a composite foamed material-filled hollow spiral drainage pipe. The drainage pipe adopts a two-layer structure design, including an outer pipe and an inner pipe arranged sequentially from the outside to the inside. The outer pipe and the inner pipe are connected by connectors. The connectors are evenly arranged between the inner pipe and the outer pipe along the length of the drainage pipe. There are 3 connectors arranged along the radial direction of the drainage pipe. The connectors are integrally formed with the inner pipe and the outer pipe. Spiral ribs are provided on the inner wall of the innermost inner pipe. The spiral ribs are threaded on the inner wall of the inner pipe. The inner pipe is Φ151mm, and the pitch between the spiral ribs is 181mm.

[0048] A sound-absorbing layer is installed between the outer and inner pipes. This layer is filled with expanded foam material, which, by weight percentage, comprises: 40% polyurethane prepolymer, 30% rubber granules, and 30% steel slag. The rubber granules have a particle size of 100 mesh, and the steel slag has a mesh size of 5-10 mesh. Both the outer and inner pipes are tubular with circular cross-sections. The outer diameter of the drainage pipe is 160mm, and its thickness is 4.5mm. The inner pipe has a thickness of 1.8mm, the outer pipe has a thickness of 1.8mm, and the sound-absorbing layer has a thickness of 1.6mm.

[0049] The drainage pipes were manufactured using the method described in Example 1, and the density of the expanded foam material was 2000 kg / m³. 3 .

[0050] Example 4

[0051] This embodiment provides a composite foamed material-filled hollow spiral drainage pipe. The drainage pipe adopts a two-layer structure design, including an outer pipe and an inner pipe arranged sequentially from the outside to the inside. The outer pipe and the inner pipe are connected by connectors. The connectors are evenly arranged between the inner pipe and the outer pipe along the length of the drainage pipe. There are 3 connectors arranged along the radial direction of the drainage pipe. The connectors are integrally formed with the inner pipe and the outer pipe. Spiral ribs are provided on the inner wall of the innermost inner pipe. The spiral ribs are threaded on the inner wall of the inner pipe. The inner pipe is Φ151mm, and the pitch between the spiral ribs is 181mm.

[0052] A sound-absorbing layer is installed between the outer and inner pipes. This layer is filled with expanded foam material, which, by weight percentage, comprises: 50% polyurethane prepolymer, 25% rubber granules, and 25% steel slag. The rubber granules have a particle size of 100 mesh, and the steel slag has a mesh size of 10-20 mesh. Both the outer and inner pipes are tubular with circular cross-sections. The outer diameter of the drainage pipe is 160 mm, and its thickness is 4.5 mm. The inner pipe has a thickness of 1.8 mm, the outer pipe has a thickness of 1.8 mm, and the sound-absorbing layer has a thickness of 0.9 mm.

[0053] The drainage pipes were manufactured using the method described in Example 1, and the density of the expanded foam material was 1800 kg / m³. 3 .

[0054] Example 5

[0055] This embodiment provides a composite foamed material-filled hollow spiral drainage pipe. The drainage pipe adopts a two-layer structure design, including an outer pipe and an inner pipe arranged sequentially from the outside to the inside. The outer pipe and the inner pipe are connected by connectors. The connectors are evenly arranged between the inner pipe and the outer pipe along the length of the drainage pipe. There are 3 connectors arranged along the radial direction of the drainage pipe. The connectors are integrally formed with the inner pipe and the outer pipe. Spiral ribs are provided on the inner wall of the innermost inner pipe. The spiral ribs are threaded on the inner wall of the inner pipe. The inner pipe is Φ151mm, and the pitch between the spiral ribs is 181mm.

[0056] A sound-absorbing layer is installed between the outer and inner pipes. This layer is filled with expanded foam material, which, by weight percentage, comprises: 60% polyurethane prepolymer, 20% rubber granules, and 20% steel slag. The rubber granules have a particle size of 100 mesh, and the steel slag has a mesh size of 10-20 mesh. Both the outer and inner pipes are tubular with circular cross-sections. The outer diameter of the drainage pipe is 160 mm, and its thickness is 4.5 mm. The inner pipe has a thickness of 1.8 mm, the outer pipe has a thickness of 1.8 mm, and the sound-absorbing layer has a thickness of 0.9 mm.

[0057] The drainage pipes were manufactured using the method described in Example 1, and the density of the expanded foam material was 2500 kg / m³. 3 .

[0058] Example 6

[0059] This embodiment provides a composite foamed material-filled hollow spiral drainage pipe. The drainage pipe adopts a two-layer structure design, including an outer pipe and an inner pipe arranged sequentially from the outside to the inside. The outer pipe and the inner pipe are connected by connectors. The connectors are evenly arranged between the inner pipe and the outer pipe along the length of the drainage pipe. There are 3 connectors arranged along the radial direction of the drainage pipe. The connectors are integrally formed with the inner pipe and the outer pipe. Spiral ribs are provided on the inner wall of the innermost inner pipe. The spiral ribs are threaded on the inner wall of the inner pipe. The inner pipe is Φ151mm, and the pitch between the spiral ribs is 181mm.

[0060] A sound-absorbing layer is installed between the outer and inner pipes. This layer is filled with expanded foam material, which, by weight percentage, comprises: 50% polyurethane prepolymer, 25% rubber granules, and 25% steel slag. The rubber granules have a particle size of 100 mesh, and the steel slag has a mesh size of 10-20 mesh. Both the outer and inner pipes are tubular with circular cross-sections. The outer diameter of the drainage pipe is 160 mm, and its thickness is 4.5 mm. The inner pipe has a thickness of 1.8 mm, the outer pipe has a thickness of 1.8 mm, and the sound-absorbing layer has a thickness of 0.9 mm.

[0061] The drainage pipes were manufactured using the method described in Example 1, and the density of the expanded foam material was 2000 kg / m³. 3 .

[0062] Example 7

[0063] This embodiment provides a composite foamed material-filled hollow spiral drainage pipe. The drainage pipe adopts a three-layer structure design, such as... Figure 3 As shown, it includes an outermost outer tube, a middle inner tube, and an innermost inner tube. The connectors include a first connector and a second connector. The outermost outer tube and the middle inner tube are connected by the first connector at intervals, and the middle inner tube and the innermost inner tube are connected by the second connector at intervals. The first connector and the second connector are staggered. There are four of each of the first and second connectors. The connectors are integrally formed with the inner and outer tubes. The inner wall of the innermost inner tube is provided with spiral ribs. The spiral ribs are threaded on the inner wall of the inner tube. The inner tube is Φ151mm, and the pitch between the spiral ribs is 181mm.

[0064] Sound-absorbing layers are installed between the outer and inner tubes, and between the inner tubes themselves. These layers are filled with expanded foam material, which, by weight percentage, comprises: 40% polyurethane prepolymer, 30% rubber granules, and 30% steel slag. The rubber granules have a particle size of 100 mesh, and the steel slag has a mesh size of 10-20 mesh. Both the outer and inner tubes are tubular with circular cross-sections. The outer diameter of the drainage pipe is 160 mm, and its thickness is 4.5 mm. The innermost inner tube has a thickness of 1.5 mm, the middle inner tube has a thickness of 1.2 mm, and the outer tube has a thickness of 1.2 mm. The sound-absorbing layer between the inner tubes and between the inner and outer tubes has a thickness of 0.45 mm.

[0065] The drainage pipes were manufactured using the method described in Example 1, and the density of the expanded foam material was 2000 kg / m³. 3 .

[0066] Comparative Example 1

[0067] The drainage pipe is a cast iron pipe with the same pipe parameters and connection method as in Example 1.

[0068] Comparative Example 2

[0069] The drainage pipe is a PVC solid-wall spiral pipe with the same pipe parameters and connection method as in Example 1.

[0070] Comparative Example 3

[0071] The drainage pipe is a solid PVC pipe with the same pipe parameters and connection method as in Example 1.

[0072] Comparative Example 4

[0073] This comparative example provides a drainage pipe with the same structure as in Example 1. The difference lies in the foaming material used for the sound-absorbing layer between the outer and inner pipes. The foaming material in this comparative example comprises the following components by weight percentage: 60% polyurethane prepolymer, 30% rubber particles, and 10% steel slag. The rubber particles have a particle size of 100 mesh, and the steel slag has a mesh size of 10 to 20 mesh.

[0074] The drainage pipes were manufactured using the method described in Example 1, and the density of the expanded foam material was 1200 kg / m³. 3 .

[0075] Comparative Example 5

[0076] This comparative example provides a drainage pipe with the same structure as in Example 1. The difference lies in the foaming material used for the sound-absorbing layer between the outer and inner pipes. The foaming material in this comparative example comprises the following components by weight percentage: 50% polyurethane prepolymer, 15% rubber particles, and 35% steel slag. The rubber particles have a particle size of 100 mesh, and the steel slag has a mesh size of 10 to 20 mesh.

[0077] The drainage pipes were manufactured using the method described in Example 1, and the density of the expanded foam material was 2000 kg / m³. 3 .

[0078] Comparative Example 6

[0079] This comparative example provides a drainage pipe with the same structure as in Example 1. The difference lies in the foaming material used for the sound-absorbing layer between the outer and inner pipes. The foaming material in this comparative example comprises the following components by weight percentage: 25% polyurethane prepolymer, 40% rubber particles, and 35% steel slag. The rubber particles have a particle size of 100 mesh, and the steel slag has a mesh size of 10 to 20 mesh.

[0080] The drainage pipes were manufactured using the method described in Example 1, and the density of the expanded foam material was 2000 kg / m³. 3 .

[0081] Comparative Example 7

[0082] This comparative example provides a drainage pipe with the same structure as in Example 1, except that 10 connectors are provided along the radial direction of the drainage pipe. The drainage pipe is manufactured using the method of Example 1.

[0083] Comparative Example 8

[0084] This comparative example provides a drainage pipe with the same structure as in Example 1, except that the pitch between the spiral ribs on the inner wall of the innermost inner pipe is 0.8 times the pipe diameter, and the pitch is 121 mm. The drainage pipe is manufactured using the method of Example 1.

[0085] Comparative Example 9

[0086] This comparative example provides a drainage pipe with the same structure as in Example 1, except that the pitch between the spiral ribs on the inner wall of the innermost inner pipe is 1.5 times the pipe diameter, and the pitch is 226 mm. The drainage pipe is manufactured using the method of Example 1.

[0087] Comparative Example 10

[0088] This comparative example provides a drainage pipe with the same structure as in Example 1, except for the thickness: the inner pipe is 1.96 mm thick, the outer pipe is 1.96 mm thick, and the sound-absorbing layer is 0.58 mm thick, which is 15% of the total thickness of the inner and outer pipes. The drainage pipe is manufactured using the method described in Example 1.

[0089] Comparative Example 11

[0090] This comparative example provides a drainage pipe with the same structure as Example 1, except for the thickness. The inner pipe is 1.67 mm thick, the outer pipe is 1.67 mm thick, and the sound-absorbing layer is 1.16 mm thick, which is 35% of the total thickness of the inner and outer pipes. The drainage pipe is manufactured using the method of Example 1. However, the sound-absorbing layer thickness of the drainage pipe in this comparative example is too large, resulting in a decrease in the mechanical strength of the pipe.

[0091] Comparative Example 12

[0092] This comparative example provides a drainage pipe with the same structure as in Example 1, except that the foaming material of the sound-absorbing layer is different; the foaming material used is only polyurethane prepolymer. The drainage pipe is manufactured using the method described in Example 1.

[0093] Comparative Example 13

[0094] This comparative example provides a drainage pipe with the same structure as in Example 1, except that the foaming material of the sound-absorbing layer is different. The foaming material, by weight percentage, comprises: 57% polyurethane prepolymer and 43% rubber granules. The rubber granules have a particle size of 100 mesh and no steel slag is added. The drainage pipe is manufactured using the method described in Example 1.

[0095] Comparative Example 14

[0096] This comparative example provides a drainage pipe with the same structure as in Example 1, except that the foaming material of the sound-absorbing layer is different. The foaming material, by weight percentage, comprises: 57% polyurethane prepolymer and 43% steel slag. The steel slag has a mesh size of 10-20 mesh, and no rubber particles are added. The drainage pipe is manufactured using the method described in Example 1.

[0097] Test Example 1

[0098] The drainage pipes of Examples 1-7 were tested and found that the tensile yield strength and elongation at break met the mechanical performance requirements, the impact test showed no cracking, and the water tightness and air tightness tests showed no leakage. This indicates that the drainage pipes prepared by the present invention have advantages such as excellent anti-aging and weather resistance, light weight, corrosion resistance, good flexibility, high impact strength, good air tightness, convenient and quick installation, energy saving, hygiene and environmental protection.

[0099] Test Example 2

[0100] The drainage pipes of Examples 1-7 and Comparative Examples 1-14 were installed as sewer pipes in a standard laboratory and tested according to the relevant requirements of Chapter 4 of "Noise Test Method for Building Drainage Pipeline Systems" CJ / T 312-2009 and "On-site Test Standard for Noise of Domestic Drainage Systems in Civil Buildings" T / CECS 1511-2023. The constant flow water test method was adopted, and the test results are shown in Table 1.

[0101] Table 1. Laboratory test results of sound pressure level of drainage pipes in the examples and comparative examples.

[0102]

[0103] The noise characteristics of drainage pipes are sudden, short-lasting, and irregular. The noise is the result of the combined effects of water flow through the pipe wall space and pipe vibration. It mainly involves the complex movement of three states of matter: solid, liquid, and gas (flow noise, cavitation noise, and water hammer vibration noise). Solid noise arises from the rapid changes in water velocity and momentum, causing sudden changes in water pressure (water hammer vibration noise). Liquid noise comes from friction between the water flow and the pipe wall and air, as well as the impact vibration of water on the pipe. Gas noise arises from dissolved air released from the water flow, accumulating at the top of the pipe to form gas clouds, causing localized pressure impacts. Air noise is generated by sound waves produced by the collision of water flow with the pipe wall; structural noise is the transmission of pipe vibration caused by the vertical impact of water flow.

[0104] Based on the 1 / 1 octave band test results in Table 1 above, Example 1 achieved efficient noise reduction across the entire frequency band (125-4000 Hz), especially exhibiting excellent performance in the high-frequency range (2000-4000 Hz), with a noise level reaching 41 dB at 4000 Hz, demonstrating the excellent absorption capacity of the foam material for high-frequency airborne sound. It also showed good performance in the low-frequency range (125-500 Hz), with noise levels of 37-40 dB, proving that the spiral rib structure effectively suppressed water flow impact and structural vibration. Examples 2-6 also demonstrated good noise reduction effects. The drainage pipe of this invention uses a spiral flow guide combined with foam material filling, where the spiral flow guide reduces low-frequency noise, and the foam material reduces high-frequency noise, achieving efficient noise reduction across a wide frequency band.

[0105] The drainage pipes in Comparative Examples 2 and 3 can only reduce noise in a single frequency band, resulting in poor overall noise reduction effect. Comparative Examples 4-6 and 12-14 show that the composition and proportion of foaming material in the drainage pipe are the key factors for achieving noise reduction effect. If the proportion of polyurethane, rubber particles, and steel slag deviates from the range required by this invention (40-60%, 20-40%, 20-35%), or if any component is missing, its noise reduction performance in the key frequency band (such as the absence of rubber in Comparative Example 5, which caused the mid-frequency 500Hz noise to rise to 45dB) will be significantly reduced. This also proves that the material proportion range claimed by this invention is the optimal and necessary range verified by a large number of experiments, rather than being arbitrarily selected.

[0106] Comparative Example 7 shows that when the number of connectors exceeds eight, the sound insulation performance deteriorates due to the "sound bridge" effect. Comparative Examples 8 and 9 show that the pitch of the spiral ribs in the drainage pipe is 1.1 to 1.2 times the diameter of the inner pipe. If the pitch of the spiral ribs becomes smaller or larger, the noise reduction effect deteriorates. In Comparative Example 10, the proportion of the sound-absorbing layer to the total thickness of the inner and outer pipes is too low, failing to achieve the effect of reducing high-frequency noise. The above description indicates that the composition and proportion of the foaming material, the number of connectors, the pitch of the spiral ribs, and the thickness of the sound-absorbing layer are the key structural parameters in the technical solution of this invention.

[0107] The noise levels of the drainage pipes in Examples 1-7 and Comparative Examples 1-14 were measured under laboratory conditions and different water flow rates. The results are shown in Table 2 below. Based on GB / T 3785.1-2023 "Electroacoustics - Sound level meters - Part 1: Specifications" and IEC 61672-1:2013 "Electroacoustics - Sound level meters - Part 1: Specifications", the equivalent continuous A-weighted sound level LAeq was obtained after A-weighting network correction and energy averaging calculation. The cost, unit weight, relative installation time, and service life of the drainage pipes were also calculated, as shown in Table 3.

[0108] Table 2. Laboratory test results of the drainage pipes in the examples and comparative examples under different water flow conditions.

[0109]

[0110] Table 2 simulates actual operating conditions with different water flow rates (1-5 L / s), demonstrating the stability and reliability of the noise reduction effect of the present invention. Example 1 exhibits a noise level of only 45 dB at the maximum water flow rate (5 L / s), significantly lower than the solid-wall pipe of Comparative Example 3 (54 dB) and the spiral pipe of Comparative Example 2 (50 dB). This indicates that the advantages of the present invention are more pronounced under high load and most demanding operating conditions, solving the industry pain point of noise runaway in existing products at peak flow rates and meeting the practical needs of modern residences. With increasing water flow rate, the noise levels of the drainage pipes in Examples 1-7 increase gradually, while the noise levels of the drainage pipes in Comparative Examples 1-14 increase dramatically with increasing water flow rate. This demonstrates that the technical solution of the present invention (a sound-absorbing layer filled with foamed material in a specific ratio + spiral reinforcement) endows the pipe with a dynamic noise reduction capability, meaning that its noise reduction mechanism works effectively regardless of the water flow rate.

[0111] Table 3. Comparison of overall performance of drainage pipes in the examples and comparative examples

[0112]

[0113] Table 3 provides a comprehensive evaluation of drainage pipes based on noise level, cost, unit weight, relative installation time, and service life. Example 1 shows the best overall performance, indicating that the present invention does not sacrifice other performance metrics for a single noise reduction index, but rather provides a solution with optimal overall performance.

[0114] Comparative Example 1 uses cast iron pipe. While achieving a similar service life (50 years), and despite its noise reduction properties, the weight of the cast iron pipe is significantly greater than that of the plastic drainage pipe in the embodiment, even with the same specifications. Comparative Examples 2 and 3 use ordinary plastic pipe. At the cost of an acceptable increase in cost and weight (approximately double the cost and increase in weight by about 60%), they achieve a leap in noise reduction performance (noise reduction of over 10 dB) and a significant extension of lifespan. This demonstrates that the technological upgrade brings value far exceeding the cost increase. Data from other Comparative Examples 4-14 show that any deviation from key factors in the technical solution of this invention—the composition and proportion of the foaming material, the number of connectors, the pitch of the spiral ribs, and the thickness of the sound-absorbing layer—leads to an imbalance in overall performance, such as a surge in cost, a shortened lifespan, and inconvenient installation (e.g., increased weight due to too many connectors).

[0115] Existing technologies struggle to simultaneously address the coupling problem between structural sound conduction (low frequency) and airborne sound radiation (high frequency). However, this invention utilizes a spiral flow guide combined with hollow foam material. The spiral flow guide reduces water flow impact, while the foam material filling the sound-absorbing layer combines sound absorption and damping functions to achieve broadband noise reduction.

[0116] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A composite foamed material-filled hollow spiral drainage pipe, comprising an outer layer pipe (1) and at least one inner layer pipe (2) arranged sequentially from the outside to the inside, characterized in that, The outer tube (1) is connected to the inner tube (2), and the inner tube (2) is connected to the inner tube (2) by a connector (3). The inner wall of the innermost inner tube (2) is provided with a spiral rib (4). The spiral rib (4) is threaded on the inner wall of the innermost inner tube (2). The pitch of the spiral rib (4) is 1.1 to 1.2 times the diameter of the innermost inner tube (2). The connector (3) is evenly arranged between the inner tube (2) and the outer tube (1) or between the inner tube (2) and the inner tube (2) along the length of the drainage pipe. There are 3 to 8 connectors arranged along the radial direction of the drainage pipe. The drainage pipe adopts a three-layer structure design, including the outermost outer layer pipe (1), the middle inner layer pipe (2), and the innermost inner layer pipe (2). The connector (3) includes a first connector and a second connector. The outermost outer layer pipe (1) and the middle inner layer pipe (2) are connected at intervals by the first connector, and the middle inner layer pipe (2) and the innermost inner layer pipe (2) are connected at intervals by the second connector. The first connector and the second connector are staggered. A sound-absorbing layer (5) is provided between the outer tube (1) and the inner tube (2), and between the inner tube (2) and the inner tube (2). The sound-absorbing layer (5) is filled with expanded foam material. The thickness of the sound-absorbing layer (5) is 20-30% of the total thickness of the inner tube (2) and the outer tube (1). The foam material comprises the following components by weight percentage: 40-60% polyurethane prepolymer, 20-40% rubber particles, and 20-35% steel slag. The rubber particles have a particle size of 100 mesh, the steel slag has a mesh size of 5-20 mesh, and the density of the foam material is 1800-2500 kg / m³. 3 .

2. The composite foamed material-filled hollow spiral drainage pipe according to claim 1, characterized in that, The connector (3) is integrally formed with the inner tube (2) and the outer tube (1).

3. A method for manufacturing a hollow spiral drainage pipe filled with composite foamed material as described in any one of claims 1-2, characterized in that, Includes the following steps: S1. Add the plastic material to the screw extruder; S2. Connect the extrusion molding die corresponding to the drainage pipe structure to the screw extruder, and extrude to obtain a pipe including the inner tube (2), the outer tube (1), and the connector (3). Simultaneously mold the spiral rib (4) during the extrusion process. S3. The pre-mixed foaming material is injected into the sound-absorbing layer (5) through a high-pressure injection process to obtain the drainage pipe.

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