Metal pipes for construction sites

Abstract

To provide a metal pipe material that can reduce noise caused by impacts to metal pipes used at construction sites. [Solution] A metal pipe material for construction sites in which resin particles are sealed inside the metal pipe and both ends of the metal pipe are sealed.

Description

Technical Field

[0001] The present invention relates to metal materials for construction sites, and more particularly to metal pipes used for scaffolds, shoring, etc. at construction sites.

Background Art

[0002] At construction sites, metal pipes such as single pipes are widely used for temporary scaffolds, shoring, and single-pipe barricades for work. When an impact such as a drop or a blow is applied to the metal pipe during work, a high-pitched and loud metallic sound (hereinafter referred to as noise) is generated, which has contributed to the noise problem.

[0003] As a technique for reducing the noise of metal pipes, for example, Patent Document 1 proposes a metal pipe filled with foamed resin inside. Further, Patent Document 2 proposes a temporary material in which a sheet-like vibration damping material is attached to the outer surface and / or the inner surface of the temporary material.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] An object of the present invention is to provide a metal pipe material for a construction site that can reduce noise caused by impacts on metal pipes used at a construction site.

Means for Solving the Problems

[0006] [1] A metal pipe material for a construction site in which resin particles are enclosed inside a metal pipe and both ends of the metal pipe are sealed. [2] The metal pipe material for construction sites according to [1], wherein the resin particles consist of elastic resin particles and non-elastic resin particles. [3] The metal pipe material for construction sites according to [1] or [2], wherein the weight ratio of the elastic resin particles to the non-elastic resin particles is 10:90 to 90:10. [4] A metal pipe material for construction sites according to any one of [1] to [3], wherein the volume-based filling rate of the resin particles is 20% to 70%. [5] The resin particles have an average particle size of 1 to 20 mm. [1] to [4] The metal pipe material for construction sites as described above. [Effects of the Invention]

[0007] The metal pipe material of the present invention can reduce noise generated when metal pipes are struck. Therefore, the metal pipe material of the present invention contributes to solving noise problems at construction sites. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 is a schematic diagram illustrating a metal pipe material according to one embodiment of the present invention. [Figure 2] Figure 2 is a schematic diagram illustrating a metal pipe material according to another embodiment of the present invention. [Figure 3] Figure 3 is a schematic diagram illustrating the metal tubing used in the example. [Figure 4] Figure 4 is a schematic diagram illustrating the noise measuring device of the embodiment. [Figure 5] Figure 5 is a graph showing an example of conventional noise. [Figure 6] Figure 6 is a graph showing the relationship between the resin particle mixing ratio and noise level in the example. [Figure 7] Figure 7 is a graph showing the relationship between the resin particle blending ratio in the example and the highest pitch. [Figure 8] Figure 8 is a schematic diagram showing an example of a mounting bracket attached to the handrail of temporary scaffolding. [Figure 9] Figure 9 is a graph showing the noise levels in Example (No. 4). [Modes for carrying out the invention]

[0009] The inventors performed noise measurements on commonly used single-pipe scaffolding (metal pipes with no filling in the hollow section and no sealing at both ends) by striking them as described in the examples, and created noise waveforms based on the results. As shown in Figure 5, a loud impact sound is generated at the moment the hammer strikes the single-pipe scaffolding, and then gradually decays. The height of the peak represents the loudness of the sound; the higher the peak, the louder the impact sound produced at the time of the hammer impact. The width of the peak (hereinafter referred to as the peak width) represents the reverberation; the wider the peak width, the more the sound reverberates. In the case of Figure 5, the impact sound at the time of the hammer impact is 100 dBA or more, and the reverberation continues for about 3 seconds afterward. The inventors' research revealed that to suppress noise, it is necessary not only to reduce the loud sound produced during impact (sometimes called impact sound or maximum volume), but also to reduce the reverberation after the impact (sometimes called reverberation sound or total noise). The inventors then discovered that the metal pipe material of the present invention can reduce both impact sound and reverberation sound, thereby suppressing noise, leading to the present invention.

[0010] The structure of the metal tubing material of the present invention will be explained with reference to Figure 1. (A) is a longitudinal side view of the metal pipe, (B) is a cross-sectional view of the metal pipe in Figure 1(A) cut along line BB, and (C) is a front view of the metal pipe in Figure 1(A) viewed from direction A. The metal pipe material of the present invention has resin particles 3 sealed inside the metal pipe 1, and both ends of the metal pipe 1 are sealed with a sealing material 2. Figures 2 and 3 show other embodiments with different forms of the sealing material 2.

[0011] metal tube The metal pipe 1 is not particularly limited and can be any type of metal pipe commonly used at construction sites, such as scaffolding, support structures, and single-pipe barricades. Examples include carbon steel pipes, alloy steel pipes, stainless steel pipes, and iron pipes. The metal pipe 1 may also be a non-ferrous metal pipe such as an aluminum pipe, titanium pipe, or lead pipe. The shape of the metal pipe 1, that is, the outer shape formed by the pipe wall, may be either a round pipe (Fig. 1(C): round pipe) or a square pipe (not shown: square pipe).

[0012] Sealing material The sealing material 2 prevents the resin particles 3 encapsulated inside the metal pipe 1, that is, inside the hollow part of the metal pipe 1, from flowing out. The sealing material 2 is attached to the openings at both ends of the metal pipe 1 respectively. The sealing material 2 closes the openings of the metal pipe 1 so that the resin particles 3 encapsulated in the hollow part of the metal pipe 1 do not flow out. The openings of the metal pipe 1 may be closed, for example, by inserting a part (Fig. 1) or all (Fig. 3) of the sealing material 2 into the openings of the metal pipe 1 (insertion cap), or as shown in Fig. 2, fitting the sealing material 2 to the outer diameter of the opening of the metal pipe 1 to close the opening (outer cap). The material of the sealing material 2 is not particularly limited. Examples include foamed resin caps such as foamed polyurethane, foamed polystyrene, foamed polyethylene, and foamed polypropylene; natural rubber caps; synthetic rubber caps; non-foamed resin caps such as polyethylene, polypropylene, polyethylene terephthalate, and vinyl chloride, and metal caps. Note that non-foamed resin refers to a resin that does not involve foaming (a state where air bubbles are dispersed in the resin). A preferred embodiment of the sealing material 2 is an insertion cap made of foamed resin. This not only prevents the resin particles 3 from flowing out, but also suppresses the vibration of the metal pipe 1 when the metal pipe 1 is struck and reduces the generation of collision sounds. Also, the foamed resin may be either open-cell or closed-cell, but open-cell foamed resin is preferred. If it is open-cell foamed resin, water that has entered the inside of the metal pipe 1 due to rain or the like can be easily drained.

[0013] [ Resin particles The resin particles 3 are encapsulated inside the metal pipe 1 to absorb and attenuate the impact sound generated by the impact applied to the metal pipe 1, and also attenuate the vibration of the metal pipe due to the impact. As a result, a synergistic effect of absorption and attenuation of the impact sound and attenuation of the reverberation sound occurs, reducing the noise. In this invention, the resin constituting the resin particles 3 may be either a natural resin or a synthetic resin, or a mixed resin of a natural resin and a synthetic resin. The synthetic resin may be either an elastomer or a plastic. The natural resin is preferably natural rubber. The resin particles 3 may be made from various used resin products in particulate form, and by reusing resin products, environmental impact and manufacturing costs can be reduced.

[0014] When the volume of resin particles 3 sealed inside the metal tube 1 is taken as 100%, the proportion of the volume occupied by the resin particles 3 is preferably at least 20% from the viewpoint of reducing impact noise and reverberation. The higher the filling rate of the resin particles 3, the more impact sound can be absorbed and attenuated, and the more vibrations propagating through the metal pipe 1 can be diffused, thereby reducing noise. Therefore, the filling rate of the resin particles 3 is more preferably 30% or more, even more preferably 40% or more, and even more preferably 50% or more. The upper limit of the filling rate of the resin particles 3 is preferably 70% or less, more preferably 60% or less. If the filling density of the resin particles 3 increases, the weight of the metal pipe increases, reducing its handling properties. Furthermore, while a sufficient noise reduction effect can be obtained when the filling density of the resin particles 3 is within the above range, the noise reduction effect saturates when the filling density is increased beyond a certain point. Therefore, considering both the noise reduction effect and handling properties, it is preferable to keep the filling density of the resin particles 3 within the above range. The filling rate was measured by filling a metal tube 1 with resin particles 3 while tapping it twice per second with a wooden rod.

[0015] The size of the resin particles 3 is not particularly limited, but the average particle size is preferably 1 to 20 mm, more preferably 1 to 15 mm, and even more preferably 1 to 10 mm. In this invention, it is a preferred embodiment to use resin particles 3 having different average particle diameters or resin particles 3 having substantially the same average particle diameter. Furthermore, if the average particle size is within the above range, it is preferable because it can improve the efficiency of filling into the metal pipe 1. For example, handrails used in temporary scaffolding may have mounting brackets with openings (holes in the figure) as outer caps at both ends of the metal pipe 1, as shown in Figure 8. Therefore, the smaller the resin particles, the more efficiently the resin particles 3 can be filled into the metal pipe 1 even through the small openings provided in the mounting brackets, which is desirable.

[0016] The shape of the resin particles is not particularly limited, and various shapes such as pellets, spheres, and irregularly shaped crushed particles can be used. However, pellets or spheres are preferred, and spheres are more preferred, considering the ease of insertion into the metal tube 1. The resin particles may be the same shape, or resin particles of different shapes may be used in combination. Furthermore, the resin particles 3 may be solid or hollow. Preferably, they are hollow resin particles with open ends (for example, straw-shaped resin particles) or spherical or pellet-shaped resin particles 3 with hollow interiors. Hollow or hollow resin particles 3 contribute to weight reduction and have an excellent noise reduction effect.

[0017] In a preferred embodiment of the present invention, it is preferable to use a combination of elastic resin particles and inelastic resin particles for the resin particles 3. By using a combination of elastic and inelastic resin particles, a superior effect is achieved in reducing impact noise and reverberation noise. In the present invention, the distinction between elastic resin particles and inelastic resin particles is as follows: resin particles that return to their original shape after being deformed by an external force are called elastic resin particles, and those that do not return to their original shape are called inelastic particles. Alternatively, for example, resin particles with a Shore A hardness of 70 or less may be called elastic resin particles, and those with a Shore A hardness greater than 70 may be called inelastic resin particles.

[0018] Elastic resin particles Elastic resin particles have particularly excellent impact sound absorption and reverberation sound absorption properties. The elastic resin particles are preferably foamed resin particles and / or elastomer particles. Foamed resin particles are particles of a foam containing closed cells and / or open cells within the resin. Preferably, the foamed resin particles have closed cells. Foamed resin particles with closed cells are preferred because they have higher impact sound absorption and reverberation sound absorption properties. Examples of foamed resin particles include foamed polyurethane resin particles, foamed polystyrene resin particles, foamed polyolefin resin particles (especially foamed polyethylene resin particles), foamed phenol resin particles, foamed polyvinyl chloride resin particles, foamed urea resin particles, foamed silicone resin particles, foamed polyimide resin particles, foamed melamine resin particles, and foamed ABS resin particles; foamed synthetic rubber particles such as foamed isoprene rubber particles, foamed SBR rubber particles, foamed butadiene rubber particles, foamed chloroprene rubber particles, foamed nitrile rubber particles, and foamed butyl rubber particles; and foamed natural rubber particles. These may be used individually or in combination of two or more types. The elastomer particles are preferably made of natural rubber; synthetic rubbers such as styrene-butadiene rubber, butadiene rubber, isoprene rubber, butyl rubber, chloroprene rubber, nitrile rubber, ethylene propylene rubber, urethane rubber, and silicone rubber; and blends of natural and synthetic rubbers are also examples. These may be used individually or in combination of two or more types. Furthermore, the foamed resin particles and elastomer particles may also be resin particles obtained by physically recycling foamed resins used in cushioning materials and packaging materials, or elastomers used in tires, etc., through methods such as crushing or chemical recycling such as dissolution.

[0019] Inelastic resin particles The vibrations of the metal tube 1, generated by an impact, are transmitted to the inelastic particles, dispersing the impact vibrations and attenuating the impact vibrations propagating through the metal tube, thereby reducing impact noise and reverberation. The non-elastic resin particles may be thermoplastic resins, thermosetting resins, or both in combination. Furthermore, the non-elastic resin particles are preferably non-foaming resin particles. Non-foaming resin particles are non-foaming (solid resin particles) that do not contain air bubbles within the resin.

[0020] Non-foaming resin particles are not particularly limited, and examples include solid resin particles such as polyurethane resin particles, polystyrene resin particles, polyolefin resin particles (especially polyethylene resin particles), phenolic resin particles, polyvinyl chloride resin particles, urea resin particles, silicone resin particles, polyimide resin particles, melamine resin particles, and ABS resin particles. These may be used individually or in combination of two or more types. Furthermore, non-foaming resin particles may also be resin particles obtained by physically recycling or chemically recycling hard resin products such as polypropylene that were used in daily necessities and industrial products.

[0021] The weight ratio (sometimes called the blending ratio) of elastic resin particles to non-elastic resin particles is preferably 10:90 to 90:10, more preferably 10:90 to 50:50, even more preferably 20:80 to 40:60, and even more preferably 20:80 to 30:70. When elastic resin particles and non-elastic resin particles are used in combination, the noise reduction effect tends to saturate as the proportion of elastic resin particles increases. On the other hand, the noise reduction effect also tends to saturate as the proportion of non-elastic resin particles decreases. Taking these tendencies into consideration, the present invention defines the above-mentioned preferred range as the proportion of the particles that provides a remarkable effect. [Examples]

[0022] The present invention will be described in more detail below with reference to examples, but the present invention is not limited by the following examples, and it is certainly possible to implement it with appropriate modifications within the scope that is consistent with the spirit of the preceding and following descriptions, and all such modifications are included within the technical scope of the present invention.

[0023] Experiment 1 Cast object (Fig. 3) A cast body 4 (Figure 3) was created by filling the hollow part of a 50cm long, 48.6mm outer diameter (46.2mm inner diameter) steel pipe 1a with resin particles 3, and then inserting 5cm long sealing material 2 (foamed urethane) into both ends of the pipe 1a to seal both ends. As resin particles 3, rubber chip particles (crushed waste tires (a mixture of natural and synthetic rubber): average particle size 5 mm or less: elastic resin particles) and polypropylene pellets (non-elastic resin particles): cylindrical bodies with a diameter of approximately 3.3 mm and a height of approximately 5 mm) were used. The mixing ratio (weight ratio) of resin particles for each example is shown in Table 1. Each resin particle was thoroughly mixed in a container before being filled into the single-pipe 1a. No. 2 was filled to a 50% density, and Nos. 3-12 to a 60% density. During the filling process, the single-pipe 1a was vibrated by tapping it twice per second with a wooden stick.

[0024] Noise measurement (Figure 4) A hammer 5 weighing 574g was used as the striking object. The sound level meter was placed at a distance of 1m from the object to be struck 4. As shown in Figure 4, the hammer 5 was swung down as a pendulum from a height of 65mm towards the center of the side of the object to be struck 4. The sound volume generated when the hammer 5 struck the object to be struck 4 was measured (dBA measurement). The measurement was repeated three times. Measurements were taken every 0.1 seconds starting from the point when a sound level of 70 dBA or higher was recorded, around the time when hammer 5 struck the object 4 being targeted. Furthermore, the noise level was calculated by subtracting 70 dBA from the recorded sound level (dBA). The total noise level (reverberation) was defined as the sum of the noise from the start to the end of the measurement. The loudest sound level among the measured values ​​was defined as the maximum sound level (impact sound). The results are shown in Table 2. In the table, the percentage of total noise (%) and the percentage of maximum sound level (%) are the ratios to the total noise (100%) and maximum sound level (100%) of No. 1, which was not filled with resin particles.

[0025] [Table 1]

[0026] [Table 2]

[0027] Based on Table 2 above, Figure 6 shows a graph summarizing the proportion of elastic resin particles (%) and the total noise level (dBA), and Figure 7 shows a graph summarizing the proportion of elastic resin particles (%) and the maximum sound level (dBA).

[0028] As shown in Table 2, the experimental results showed that the total noise levels for Nos. 2-12 were reduced to 50% or less compared to No. 1, which did not have resin particles filled in the hollow section, demonstrating an excellent reverberation suppression effect. Of these, Nos. 2-7 and 12 showed a reduction in total noise level of 40% or less compared to No. 1, demonstrating a superior reverberation suppression effect. Furthermore, Nos. 4-6 had a total noise level that was 35% or less compared to No. 1, demonstrating an even superior reverberation suppression effect. Furthermore, Nos. 4 and 5 showed a total noise level 30% lower than No. 1, demonstrating an even superior reverberation suppression effect. No. 4, in particular, showed the best reverberation suppression effect. Furthermore, Figure 6 shows that, compared to a mixture of 100% elastic resin particles and 100% non-elastic resin particles, a particularly excellent reverberation suppression effect is obtained when elastic resin particles are mixed and the proportion of elastic resin particles is 20-40%.

[0029] Experimental results showed that the maximum sound volume of models No. 2-12 was suppressed compared to No. 1, which did not have resin particles filled in the hollow section, demonstrating a superior impact sound suppression effect. Of these, Nos. 4-6 and 11 showed a reduction in maximum sound volume to 93% or less compared to No. 1, demonstrating superior impact noise suppression. Furthermore, models No. 4 and 5 exhibited a maximum sound level 91% or less compared to No. 1, demonstrating even superior impact noise suppression. Furthermore, No. 4 demonstrated the best impact noise suppression effect. Furthermore, Figure 7 shows that, compared to a mixture of 100% elastic resin particles and 100% non-elastic resin particles, a particularly excellent impact noise suppression effect is obtained when elastic resin particles are mixed and the proportion of elastic resin particles is 20-40%.

[0030] In summary, based on the results above, Nos. 2-12 showed a reduction in both total noise level and maximum sound level compared to No. 1, demonstrating superior noise suppression effectiveness. Numbers 3-7 showed superior noise reduction effects. Numbers 4-6 showed even better noise suppression effects. Numbers 4 and 5 showed even better noise suppression effects. No. 4, in particular, showed the best noise reduction effect. Compared to the conventional noise waveform (Figure 5), the noise waveform of No. 4 (Figure 9) shows a significant reduction in both maximum volume (impact sound) and total noise level (reverberation).

[0031] Experiment 2 Next, we investigated the fluidity (filling properties) of the mixed resin particles, which consisted of elastic resin particles and non-elastic resin particles mixed in the predetermined proportions used in Nos. 2 to 12. Specifically, mixed resin particles (total weight as shown in Table 1) were passed through a funnel (size: bowl portion: inner diameter 120 mmφ, tube portion inner diameter 10 mm, length 90 mm) while the bowl portion was vibrated by tapping it twice per second with a wooden stick (the time until the mixed resin particles disappeared from the funnel) and the time taken for the particles to pass through was measured. The results are shown in Table 3.

[0032] [Table 3]

[0033] Samples No. 2 through 12 all had an elapsed time of 20 seconds or less and demonstrated excellent filling properties. Of these, samples No. 3 to 7, which contained 10% to 50% elastic resin particles, had an elapsed time of 14 seconds or less and exhibited superior filling properties. Furthermore, samples No. 4-6, which contained 20%-40% elastic resin particles, had an elapsed time of less than 12 seconds and exhibited even better filling properties. No. 4, in particular, exhibited the best filling properties.

[0034] Experiment 3 Using the same materials as in Experiment 1, we investigated the filling rate of resin particles and their noise suppression effect. The target object 4 was constructed in the same manner as in Experiment 1, except that it used a single-pipe iron pipe with an inner diameter of 43.8 mm and a length of 40 cm. In addition to the rubber chip particles and polypropylene pellets used in Experiment 1, iron beads (hollow bodies: 5 mm in diameter, 5 mm or 2.5 mm in height: non-elastic particles) were used as resin particle 3. The filling rate of the resin particles in each example is shown in Table 4. Noise measurements were taken under the same conditions as in Experiment 1, measuring reverberation and impact noise. The results are shown in Table 4.

[0035] [Table 4]

[0036] Compared to No. 1, which did not contain resin particles, Nos. 2-8 reduced both reverberation and impact noise. However, No. 2 (11%), which had a low resin particle filling rate, showed a lower reverberation reduction effect compared to Nos. 3-8. Furthermore, as the resin particle filling rate increased, the reduction effect on both reverberation and impact noise tended to increase, while No. 6, with a filling rate exceeding 60%, showed a low reduction effect. [Explanation of Symbols]

[0037] 1 metal tube 1a Single pipe 2. Sealing material 3 Resin particles 4 Cast object 5 Hammers

Claims

1. A metal pipe material for construction sites, in which resin particles are sealed inside the metal pipe and both ends of the metal pipe are sealed.

2. The metal pipe material for construction sites according to claim 1, wherein the resin particles consist of elastic resin particles and non-elastic resin particles.

3. The metal pipe material for construction sites according to claim 2, wherein the weight ratio of the elastic resin particles to the non-elastic resin particles is 10:90 to 90:

10.

4. The metal pipe material for construction sites according to claim 1, wherein the volume-based filling rate of the resin particles is 20% to 70%.

5. The metal pipe material for construction sites according to claim 1, wherein the resin particles have an average particle size of 1 to 20 mm.

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