Silencer device for pneumatic drive

Abstract

To provide a silencer device capable of reducing noise and pressure loss occurring at an air exhaust port or discharge port of a pneumatic drive machine such as an air cylinder, a high-pressure valve or a diaphragm pump.SOLUTION: An air exhaust port 3 or discharge of a pneumatic drive machine is attached; an inner diameter increases from a cylinder tip part 6 toward a cylinder inner part 7; a continuous bubble porous metal body 8 having a thickness of 10 mm or more is held at the rear of the cylinder inner part 7 by a lattice part 10 at a cylinder end; thin pipe system members 12 are arranged densely in an axial direction in front of the porous metal body; and the flow of high-pressure air is adjusted by the thin pipe system member 12 arranged in the front, so that generated noise is reduced by the porous metal body 8 arranged at the rear.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a silencer device that reduces noise and pressure loss generated at the air outlet or discharge port of a pneumatically driven machine such as an air cylinder, a high-pressure valve, or a diaphragm pump. [Background technology]

[0002] A typical structure of a silencer attached to the air outlet of an air cylinder, diaphragm pump, or the like is known from Utility Model Registration No. 3209711 or Japanese Patent Application Laid-Open No. 2002-371961, and can be installed, for example, as shown in Figure 7. Utility Model Registration No. 3209711 relates to a silencer including a cylindrical silencer body with a bottom attached to the air outlet of a quick exhaust valve and a cylindrical silencer cover that is longer than the silencer body and covers the silencer body with a gap at the tip. Japanese Patent Application Laid-Open No. 2011-201025 also relates to a silencer-cum-treatment device for use with blowers, vacuum pumps, and the like, which is attached to the inlet and / or outlet of a blower or vacuum pump to reduce noise caused by inflow gas and recover gas generated in a chemical reaction tank.

[0003] The silencer disclosed in Utility Model Registration No. 3209711 can reduce exhaust noise while maintaining stable operation of the rapid exhaust valve. Also, the silencer-cum-treatment device disclosed in JP 2002-371961 fills a tank with curled adsorption filter material to remove odors contained in the gas ultimately released into the atmosphere, collect cutting mist, reduce noise caused by the inflowing gas, and help prevent environmental pollution by making the gas weakly acidic. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Utility Model Registration No. 3209711 [Patent Document 2] Japanese Patent Application Laid-Open No. 2002-371961 [Patent Document 3] Japanese Patent Application Laid-Open No. 2011-201025 Summary of the Invention [Problem to be solved by the invention]

[0005] When high-pressure air (0.7 to 0.8 MPa) acts on an exhaust port, its pressure drops as it passes through a smaller-diameter outlet into a larger-diameter cylinder or the outside. The resulting drop in temperature causes the water vapor contained in the high-pressure air to liquefy and condense, resulting in a noise of over 120 dB as water droplets spray from the outlet. The silencer in Utility Model Registration No. 3209711 is a double-cylinder plastic body with a cylindrical cover that is larger and longer than the silencer body. The air exhausted from the smaller-diameter silencer body is covered by the larger and longer silencer cover, preventing the air exhaust from being exposed to the outside air and freezing. The quick exhaust valves in which this silencer is installed are attached to pumps used in semiconductor manufacturing. While this silencer can somewhat reduce the exhaust noise of the working fluid (air), it does not reduce the exhaust noise of high-pressure air (0.7 to 0.8 MPa).

[0006] When attempting to prevent noise from 0.7 to 0.8 MPa high-pressure air by enclosing a soft fibrous material inside a cylindrical silencer, the high-pressure air acts on the tip of the tube, compressing the soft material and forcing it out of the outlet. Therefore, instead of the soft material, a hard porous resin plate made of ceramic or the like is often enclosed inside the tube. The silencer-cum-treatment device of JP 2002-371961 fills a tank with a curled adsorption filter material made of spheroidal graphite cast iron or blackheart malleable cast iron containing a small amount of copper, or general steel. While this is effective in removing odors from the inflow gas passing through the tank and making it weakly acidic, it does little to reduce the noise caused by the inflow gas, and is particularly unable to reduce exhaust noise with high-pressure air such as 0.7 to 0.8 MPa.

[0007] If a hard porous resin material such as ceramic is sealed inside a hollow cylindrical silencer, condensation will be reduced somewhat and the noise will be reduced to about 95 dB at a distance of 50 cm from the sound source, but it will not go any lower. On the other hand, the air friction resistance of the high-pressure air in the silencer will increase, reducing the performance of air cylinders and diaphragm pumps, and if used continuously, water droplets will form inside the silencer, causing clogging and further reducing the performance of the air cylinder or diaphragm pump.

[0008] Based on past experience, the inventors have discovered that using a special porous metal plate for the silencer can reduce pressure loss by first diffusing the air with a metal plate located in front and then diffusing it again with a porous metal plate located in the rear, thereby redistributing the air pressure and releasing it into the air. This type of porous metal plate can prevent a sudden drop in temperature and condensation when high-pressure air is suddenly discharged. Furthermore, placing a metal or plastic thin tube member between the two porous metal members can prevent vortexes from occurring after the air passes through the porous metal plate.

[0009] Based on this finding, the inventors have already filed a patent application (Japanese Patent Application No. 2021-47007) in which they discovered that if the high-pressure air is circulated directly through the capillary tubes, excluding the front metal plate, to prevent vortexes, the air can be sufficiently diffused using only the rear metal plate, and that if the porous metal plate is made thicker, there is no need to stack two plates; instead, it is desirable to further reduce the density of the metal plate. Furthermore, they discovered that if a single-faced cardboard sheet is wrapped around the capillary tubes to regulate the flow of high-pressure air, it can be used effectively in place of a bundle of straws.

[0010] The present invention has been proposed to further improve upon the problems associated with conventional silencers for air cylinders and diaphragm pumps, and aims to provide a silencer device that can sufficiently reduce noise and pressure loss generated at the discharge port of a pneumatically driven machine such as a diaphragm pump. Another object of the present invention is to provide a silencer device that can reduce noise and pressure loss to approximately the same extent as the silencer of Japanese Patent Application No. 2021-47007, yet is smaller and less expensive. [Means for solving the problem]

[0011] The silencer device of the present invention is a hollow cylindrical device to be attached to the air outlet or discharge port of a pneumatically driven machine. This silencer device has an inner diameter that increases from the tip or discharge port toward the interior of the cylinder, and an open-cell porous metal body with a total thickness of 10 mm or more is held in place at the rear of the cylinder by a lattice section at the end of the cylinder. Furthermore, capillary members are densely arranged in the axial direction in front of the porous metal body, and the flow of high-pressure air is regulated by the capillary members arranged at the front, and then the porous metal body arranged at the rear reduces generated noise and prevents a sudden decrease in pressure of the high-pressure air.

[0012] In the silencer device according to the present invention, the porous metal body is made of a chip of 6-20 mesh metal cutting material, which is a hypereutectic material of Al-Si alloy, with powder of eutectic material of Al-Zn-Mg alloy adhered to the surface. This chip is heated to 500-600°C by passing a high current of 6000-9000 A while being pressed with a press, and only the Al-Zn-Mg alloy on the chip surface is melted, and then the pressure is released to form a porous body with a density of 0.8-1.5 g / cm. 3 Adjust to.

[0013] In the silencer device according to the present invention, the porous metal body is preferably a single piece of metal material having a thickness of 14 to 20 mm, and the thin tube member in front of the porous metal body is preferably a single-faced corrugated plastic sheet rolled into a cylindrical shape or a bundle of plastic straws. [Effects of the Invention]

[0014] In the silencer device according to the present invention, the capillary tube member disposed at the front prevents vortexes and reduces air pressure, and the porous metal body disposed at the rear diffuses the air, dispersing the air pressure and releasing it into the air, thereby reducing pressure loss and reducing noise. The porous metal body disposed at the rear is thick and has good thermal conductivity, so condensation does not occur even if the temperature drops suddenly when high-pressure air is suddenly discharged, preventing freezing due to continuous discharge of high-pressure air. Furthermore, the capillary tube member disposed at the front is made of plastic, which has poorer thermal conductivity than metal capillaries, but prevents the generation of vortexes and does not rust even if the high-pressure air contains moisture.

[0015] When the silencer device of the present invention is applied to a pneumatically driven machine, it is possible to increase the speed of extension and contraction of the arm of an air cylinder, which is an example of such a pneumatically driven machine, and thereby increase the capacity of the air cylinder. With this type of air cylinder, when high-pressure air is suddenly discharged, it is usually subjected to air friction resistance; the higher the discharge pressure, the greater the friction resistance, making it difficult to discharge quickly. On the other hand, when the air is gradually discharged, the friction resistance decreases, but the discharge time becomes longer. In this case, simply increasing the compression capacity of the compressor connected to the air cylinder, as in the past, does not increase the operating capacity.

[0016] The silencer device of the present invention can diffuse the pressure of high-pressure air, making it easier for it to become accustomed to atmospheric pressure, and then quickly discharge the high-pressure air. This rapid discharge reduces the frictional resistance of the air, and this reduced frictional resistance also reduces the noise generated. Currently, in various product manufacturing lines, many air cylinders are installed in places where rapid movement of arms that grip or release parts is required, so the silencer device of the present invention, which enables even faster movement of the cylinder arms and reduces noise, is extremely useful. [Brief explanation of the drawings]

[0017] [Figure 1] 1 is a vertical cross-sectional view of a silencer device according to the present invention. [Figure 2]FIG. 2 is a rear end view of the silencer device of FIG. 1. [Figure 3] 2 is a schematic cross-sectional view of the silencer device taken along line AA in FIG. 1. [Figure 4] FIG. 4 is a schematic cross-sectional view similar to FIG. 3, showing a modified example of a thin tube member. [Figure 5] FIG. 1 is a side view showing a single-faced corrugated cardboard sheet used as a thin tube member. [Figure 6] FIG. 10 is a schematic explanatory diagram showing the process of adhering a flat sheet to the underside of a corrugated sheet. [Figure 7] FIG. 2 is a schematic explanatory diagram illustrating a state in which the silencer device is attached to a diaphragm pump. [Figure 8] FIG. 1 is a schematic cross-sectional view showing a molding device for a porous material used in a silencer device. [Figure 9] FIG. 9 is a schematic cross-sectional view showing the molding device of FIG. 8 cut horizontally. [Figure 10] 1 is a graph showing pressure changes over time when a pressure of 0.7 MPa is released for a silencer device connected to a diaphragm pump and a commercially available silencer. [Figure 11] 1 is a graph showing noise levels over the entire frequency range at a pressure of 0.7 MPa for a silencer device connected to a diaphragm pump and a commercially available silencer. DETAILED DESCRIPTION OF THE INVENTION

[0018] The silencer device 1 (Fig. 1) according to the present invention is a hollow cylindrical device that is attached to the air outlet 3 or discharge port of a pneumatically driven machine such as a known diaphragm pump 2 (Fig. 7). As shown in Figs. 1 and 7, the silencer device 1 has a cylindrical body 5 that is attached to the air outlet 3 of the pump 2, and the inner diameter of the cylindrical body 5 increases from the cylindrical tip 6 toward the cylindrical interior 7. At the rear of the cylindrical interior, an open-cell porous metal body 8 is held by a lattice portion 10 at the cylindrical rear end, and thin tube members 12 are arranged densely in the axial direction in front of the porous metal body.

[0019] The silencer device 1 can be attached to various types of pneumatically driven machines, not limited to the diaphragm pump 2 shown in Fig. 7. Examples of this type of pneumatically driven machine include an air cylinder, a pneumatic pump, a vacuum pump, a piston pump, and a steam boiler.

[0020] In the silencer device 1, the cylindrical body 5 is made of a pressure-resistant hard plastic or metal, preferably a hard plastic, which has relatively low thermal conductivity, small temperature drop, and is easy to mold. If the cylindrical body 5 is made of plastic, bundling the capillary tube members 12 with aluminum foil tape (not shown) or using a metal capillary tube bundle allows for rapid discharge of internal static electricity via the porous metal body 8. Furthermore, screwing a ground terminal screw (not shown) into the side wall of the cylindrical body 5 and bringing its tip into contact with the aluminum foil tape or the metal capillary tube bundle prevents the cylindrical body itself from becoming charged. Therefore, even if the cylindrical body 5 is not made of an expensive metal, there is no risk of static electricity spark ignition due to charging of the cylindrical body.

[0021] The cylindrical body 5 has a hollow structure in which the inner diameter increases from a small-diameter cylindrical tip 6 connected to the pneumatic driver toward the cylindrical interior 7. The cylindrical body 5 is composed of a front cylindrical section 14 including the cylindrical tip 6 and a rear cylindrical section 16 including a lattice section 10 at the rear end, and the cylindrical sections 14, 16 each have an annular step 18 whose inner diameter increases toward the rear and an annular step 20 whose outer diameter decreases toward the front.

[0022] The variable diameter front cylindrical portion 14 has a hexagonal nut portion 22 formed on the outer periphery of the rear end of the small diameter cylindrical tip portion 6, and an inner annular step portion 24 for holding the thin tube member 12 is formed in the middle of the inner periphery of the front cylindrical portion. As shown in Figure 2, the rear end surface of the approximately cylindrical rear cylindrical portion 16 is made up of a lattice portion 10, which holds the porous metal body 8 and allows high-pressure air to pass through. The circular lattice portion 10 is formed with crossing or parallel lattice shapes 17 or a tortoiseshell shape. Moyo stomach.

[0023] During assembly, the thin tube member 12 is inserted into the front tubular section 14 from the rear and locked at the annular step 24, while the cylindrical porous metal body 8 is housed in the rear tubular section 16. When the steps 18, 20 of the front tubular section 14 and the rear tubular section 16 are joined and welded, the porous metal body 8 is locked at the lattice section 10, and the thin tube member 12 is fixed between the annular step 24 and the porous metal body 8.

[0024] The total length of the thin tube member 12 may be set to 15 to 60 mm depending on the desired breathability. The thin tube member 12 may be a plastic single-faced corrugated cardboard sheet 26 rolled into a cylindrical shape and stored in the front cylindrical portion 14, as shown in Figures 3 and 5, or a bundle of polypropylene plastic straws 28 or a bundle of metal thin tubes as shown in Figure 4. In the case of a straw bundle 28, the diameter of the thin tubes is 1.5 to 3.5 mm, and it is desirable to use the entire bundle bound together.

[0025] The thin tube members 12 must be densely arranged in the axial and radial directions in front of the porous metal body 8. The thin tube members 12 prevent pressure loss due to frictional resistance of the high-pressure air, prevent vortices from forming in the airflow of the high-pressure air that has passed through the pneumatic driver, and allow the air to flow smoothly to the porous metal body 8 behind, reducing the air pressure.

[0026] Various metal materials can be used for the porous metal body 8 as long as they have open cells. A porosity of 60% or more, preferably 65% ​​or more, is preferable from the viewpoint of breathability. As can be seen from FIGS. 1 and 2 , the porous metal body 8 is disk-shaped with a diameter of 40 to 100 mm, which is approximately the same as the inner diameter of the cylindrical interior 7. A total thickness of 10 mm or more can reduce noise, and a thickness of 14 to 20 mm is preferable because it further reduces noise. Even with high-pressure air, a porous metal body 8 with a thickness of approximately 10 mm can be used as long as the pressure is less than 0.7 MPa. In FIG. 1 , two or more layers of metal material can be stacked as the porous metal body 8 to adjust the porosity. A total thickness of more than 20 mm increases the sound-deadening effect, but increases the discharge resistance of the high-pressure air.

[0027] To manufacture the porous metal body 8, for example, 6-30 mesh metal chips 30 (FIG. 8) are used, which are cut from a hypereutectic Al-Si alloy using a lathe. The apparent density of the porous metal body 8 after molding varies depending on the width of the chips. For example, using metal chips with 10-20 mesh results in a high apparent density, while using metal chips with 6-10 mesh results in a low density. Next, 40-50 mesh metal powder of an Al-Zn-Mg alloy eutectic material is attached to the surface of the metal chips. This metal powder is made by crushing the Al-Zn-Mg alloy eutectic material to 40-50 mesh using a crusher.

[0028] To form Al-Si alloy metal chips 30 with Al-Zn-Mg alloy powder attached, a porous metal forming apparatus 32 shown in Figures 8 and 9 can be used. The forming apparatus 32 is equipped with upper and lower ceramic dies 38, 40 in a mold 34, and a pair of electrode plates 36, 36 are placed opposite each other, allowing a high current to be passed over almost the entire surface of the electrode plates 36, 36 for uniform heating. With regard to the forming apparatus 32, the relationship between the pressure applied to the metal chips 30 filled in the mold 34 and the electrical resistivity can be made closer to that of the metal itself by increasing the pressure.

[0029] In the molding device 32, a release sheet 42 is laid on the bottom of the mold 34, and then the metal chips 30 are placed approximately evenly within the mold 34, and another release sheet 42 is laid on top of them. In the mold 34, the thickness of the metal cutting material before pressure is preferably 100 mm or less. Next, a ceramic upper mold 38 is lowered, and a high current of 6000 to 9000 A is passed through it, and the material is molded into a flat plate by applying pressure while heating to, for example, about 500 to 600°C.

[0030] The filled metal chips 30 are heated to approximately 500°C until a portion of them exceeds their melting point. During this process, the Al-Si alloy in contact with the molten portion of the Al-Zn-Mg alloy on the surface melts partially due to the pressure applied, and the Al-Zn-Mg alloy and the Al-Si alloy undergo intermetallic bonding to become one body, forming a fused material. Next, when the pressure on the mold 34 is released, the Al-Si alloy chips that had been deformed by the pressure in the fused material return to their original shape, becoming porous with open cells while remaining bonded to the Al-Zn-Mg alloy, and the overall volume returns to nearly the volume before pressure was applied, with an apparent density of approximately 1 g / cm. 3 The porous metal body 8 is obtained by cutting the flat fusion material into a desired circular plane.

[0031] As mentioned above, the apparent density of the porous metal body 8 varies depending on the mesh width of the metal chips 30 used. A finer mesh width results in a higher apparent density, while a coarser mesh width results in a lower apparent density. For example, when metal chips 30 with a mesh size of 20 to 30 are used, the apparent density of the porous metal body 8 is approximately 1.2 g / cm. 3 When 10 to 20 mesh is used, the apparent density is about 1 g / cm 3 When 6 to 10 mesh is used, the apparent density is about 0.8 g / cm 3 If a porous metal body 8 having a total thickness of 10 mm or more is used in the silencer device 1, its apparent density is 0.8 to 1.5 g / cm3 in order to prevent a sudden pressure loss. 3 It is desirable that:

[0032] In the silencer device 1, as shown in FIG. 1, a thin tube member 12 is provided at the rear of the thin tube member 12. 14 When an open-cell porous metal body 8 having a diameter of 1 / 4 mm or more is arranged, the porous metal body is relatively thick, which is an effective configuration in terms of reducing noise generation and reducing pressure loss. do.

[0033] The silencer device 1 may be attached to the air outlet 3 or discharge port of various pneumatically driven machines such as a diaphragm pump 2 (FIG. 7), air cylinder, or high-pressure valve. Although not shown, when the cylindrical body 5 of the silencer device 1 is directly connected to the body of the air cylinder or pump, the small-diameter cylindrical tip may be omitted and the air outlet may be used instead. The silencer device 1 may also be housed within the body of the air cylinder or pump, in which case the shape of the cylindrical body may be modified as appropriate. If desired, wire mesh (not shown) may be attached to the front and rear end faces of the porous metal body 8 to protect it.

[0034] When the nozzle 6 of the silencer device 1 is attached to the outlet 3 of the diaphragm pump 2 (Fig. 7), high-pressure air at 0.7 to 0.8 MPa passes through the small-diameter nozzle 6 and reaches the large-diameter interior of the cylinder 7, where the expanded high-pressure air is decompressed and its temperature drops. The high-pressure air passes through the thin tube member 12, where its flow is regulated and diffused to an even pressure, and during this process, the air resistance of the passing air on the inner surface of each thin tube slightly reduces noise and air pressure, but does not drop in temperature to the extent that the water in the high-pressure air would liquefy.

[0035] Next, the high-pressure air passes through the thin tube member 12 and is sent to the porous metal body 8 at the rear, where it is further diffused evenly by the relatively thick porous metal body 8. The diffusion of the high-pressure air prevents a sudden decrease in pressure, and contact with the thick porous metal body 8, which has good thermal conductivity, alleviates a sudden drop in temperature. Furthermore, the temperature is made uniform as the air passes through the porous metal body, preventing condensation by preventing the vapor from liquefying. As a result, by dispersing the high-pressure air using the silencer device 1 before releasing it into the atmosphere, pressure loss and noise can be reduced. The silencer device 1 further reduces noise compared to commercially available silencers.

[0036] When the silencer device 1 is applied to an air cylinder, the speed at which the arms of the air cylinder extend and retract increases, thereby increasing the working capacity of the air cylinder. The working capacity of an air cylinder depends on how quickly the high-pressure air that has entered the cylinder can be discharged, and simply increasing the compression capacity of the compressor is not enough to increase the capacity of the air cylinder; it is necessary to quickly discharge the high-pressure air inside the cylinder. The silencer device 1 diffuses the air pressure, making it easier for it to adjust to atmospheric pressure, before quickly discharging the air, thereby reducing air friction resistance and significantly reducing the noise generated.

[0037] In the silencer device 1, the noise level at a given frequency can be adjusted by appropriately combining the diameter and length of the front thin tube member 12 with the thickness of the rear porous metal body 8, which has a total thickness of 10 mm or more. The silencer device 1 not only improves the performance of pneumatically driven machines, but is also beneficial to the living environment because it can dramatically reduce noise components at low frequencies below 500 Hz. However, when the noise level of low-frequency components increases, distance attenuation becomes less effective, causing noise problems by being carried farther away.

[0038] When the silencer device 1 is used to reduce the noise level of low-frequency components, distance attenuation occurs, limiting the noise to the area surrounding the silencer device, allowing it to be treated with standard sound-absorbing materials. According to the Fourier series, sound consists of high-frequency components carried on top of low-frequency waves, so if the level of the low-frequency components is high, the high-frequency components will be carried farther away. In other words, explosive noise contains infrasound (below 10 Hz) and low-frequency sounds (below 100 Hz). The silencer device 1 uses a thin tube-type member 12 to attenuate these low-frequency sounds. The thin tube-type member 12 guides the high-pressure airflow to avoid creating vortices, dispersing the air into as fine a flow as possible and releasing it into atmospheric pressure. This creates small vortices, transforming the sound into a high-pitched sound, which then adjusts to atmospheric pressure before being discharged. [Example]

[0039] Next, the present invention will be described based on examples, but the present invention is not limited to these examples. The silencer device 1 is a hollow cylindrical device attached to the outlet 3 of a known diaphragm pump 2 (Fig. 7), and the hollow cylindrical portion has an outer diameter of 80 mm, an inner diameter of 70 mm, and a length of 86 mm. As shown in Fig. 1, the silencer device 1 has a cylindrical body 5 attached to the outlet 3 of the pump 2, and the inner diameter increases from the cylindrical tip 6 toward the cylindrical interior 7, and within the cylindrical interior, a thin tube member 12 and an open-cell porous metal body 8 are densely arranged in sequence in the axial direction.

[0040] To manufacture the porous metal body 8, a 10-20 mesh metal chip 30 (FIG. 8) made of hypereutectic Al-Si alloy is used, and a 40-50 mesh metal powder made of eutectic Al-Zn-Mg alloy is attached to the surface of the metal chip. The Al-Si alloy metal chip 30 is formed using a porous metal forming device 32 shown in FIGS. 8 and 9. The forming device 32 applies a high current of 6000-9000 A and applies pressure while heating to approximately 500°C to form the chip into a flat plate.

[0041] The filled metal chips 30 are heated by pressure and heat until a portion of them exceeds their melting point. Because the Al-Zn-Mg alloy on the surface has a low melting point of approximately 480°C, the metal powder on the Al-Si alloy chip surface melts. Meanwhile, the Al-Si alloy, with its melting point of 630°C, remains unmelted and maintains a low degree of deformation. During this process, the Al-Si alloy in contact with the molten portion of the Al-Zn-Mg alloy on the surface melts due to the pressure, and the Al-Zn-Mg alloy and Al-Si alloy form an intermetallic bond, integrating to form a fused material. When the pressure is released, the deformed Al-Si alloy chips return to their original shape, remaining bonded to the Al-Zn-Mg alloy and remaining porous with open cells. The flat fused material is then cut into circular flat surfaces.

[0042] The obtained porous metal body 8 has a thickness of 16 mm and a disk shape with a diameter of 70 mm, which is almost equal to the inner diameter of the cylindrical interior 7. The apparent density of the porous metal body 8 is about 1 g / cm when the metal chips 30 are 10 to 20 mesh. 3Furthermore, the porosity of the porous metal body 8 is approximately 70% by using metal chips 30 with a mesh size of 15 to 20. In the porous metal body 8 shown in FIG. 1, one piece with a thickness of 16 mm is used to maintain the desired porosity and strength.

[0043] The thin tube members 12 are densely arranged in the axial and radial directions in front of the rear-arranged porous metal body 8, and have a length of 30 mm and an inner diameter of 70 mm. As shown in Figures 3 and 5, the thin tube members 12 are made of single-faced corrugated cardboard sheets 26 made of polyethylene, which are rolled into a cylindrical shape and stored in the front cylindrical portion 14. To manufacture the single-faced corrugated cardboard sheets 26, a flat polyethylene sheet 44 is used, as shown in Figure 5. The flat sheet 44 has a thickness of 0.2 to 0.5 mm, a width of 1.5 to 2 m, and a length of approximately 1500 m, and the width and thickness of the corrugated polyethylene sheet 46 are also approximately the same as those of the flat sheet 44.

[0044] The corrugated sheet 46 is passed between a pair of toothed rollers (not shown) to fold the sheet into a concave and convex shape at predetermined intervals, forming pulsed side surfaces. In the case of a plastic sheet, the toothed rollers are preferably heated while processing. The toothed rollers typically rotate with interlocking concave and convex circumferential surfaces.

[0045] A liquid adhesive is applied to the underside of the obtained corrugated sheet 46 by an application roller 47, and then flat sheets 44 are fed sequentially from a lower roll 48 onto the corrugated sheet 46 to bond the corrugated sheet 46 to the flat sheet 44, after which the sheets are dried by passing them through a far-infrared drying oven 50. If the sheets 44, 46 are resin sheets, they can also be welded by high frequency, dielectric heating, or ultrasonic waves, in which case the application roller 47 and drying oven 50 are not necessary. If these sheets are made of metal, they can also be spot welded or brazed.

[0046] Silencer device 1 is cylindrical, with a tapered nozzle 6 that can be attached to the outlet 3 of diaphragm pump 2 (Figure 7). The small-diameter nozzle 6 can be screwed onto the outlet 3 of pump 2. The diaphragm pump 2 in Figure 7 is a sensor-detecting type, and when high-pressure air is sent to pump chamber A, the pair of diaphragms move to the right together with the center rod (position shown in Figure 7). When the center rod reaches the far right, a sensor (not shown) detects this position, activating a controller (not shown) and switching the solenoid valve. When the solenoid valve switches, high-pressure air is sent to pump chamber B, and the diaphragms move to the left together with the center rod. When the center rod reaches the far left, another sensor (not shown) detects this position, activating the controller, switching the solenoid valve, and starting the movement to the right. This action is repeated, causing the diaphragms to continuously reciprocate, and high-pressure air of approximately 0.7 MPa is sent from outlet 3.

[0047] Within the silencer device 1, high-pressure air at approximately 0.7 MPa passes through the small-diameter tube tip 6 and reaches the inside of the tube 7, which has an inner diameter of 75 mm. The expanded high-pressure air is decompressed, its temperature drops, and it comes into contact with the thin tubing member 12 in front. This contact causes a portion of the high-pressure air to be evenly dispersed, mitigating a sudden decrease in pressure. The high-pressure air prevents a sudden drop in temperature when it comes into contact with the thin tubing member 12, and the temperature is made uniform as it passes through the thin tubing member, preventing condensation and freezing by preventing the vapor from liquefying.

[0048] The high-pressure air passes through the capillary tube member 12 without generating vortices, with its flow regulated and dispersed at uniform pressure. During this process, the air resistance of the passing air on the inner surface of each capillary tube slightly reduces noise and air pressure, but does not drop in temperature enough to liquefy moisture in the high-pressure air. The air pressure is subdivided by the capillary tube member 12, and the air is further diffused and redistributed by the porous metal body 8 at the rear before being released into the air, thereby reducing pressure loss and noise. The capillary tube member 12 is made of polypropylene, which has poorer thermal conductivity than metal, but it will not rust even if moisture is present in the high-pressure air.

[0049] For the silencer device 1 connected to the diaphragm pump 2, the solid line in Figure 10 shows the pressure change over time when the pressure at the grid portion 10 is released at 0.7 MPa. On the other hand, the dotted line in Figure 10 shows the pressure change over time when the pressure at 0.7 MPa is released at the rear end of the cylinder for a commercially available silencer from a certain air pressure drive manufacturer used as a comparison device. When high-pressure air of 0.7 MPa is fed into the silencer device 1, as shown in Figure 10, the pressure is released more quickly and the time for pressure release is shorter than with the commercially available silencer.

[0050] Next, Figure 11 shows the noise levels over the entire sound range at a pressure of 0.7 MPa for the silencer device 1 and a commercially available silencer. The noise level is calculated by averaging the squared signal of the sound pressure, and a time-weighted characteristic with a time constant of 125 ms is used as the F characteristic using the time constant of this average. The F characteristic means a flat characteristic, and there is no change in the frequency characteristic relative to the sound pressure input to the microphone. When analyzing the noise frequency, a filter is connected after the sound level meter to analyze the frequency, and the correct analysis is performed using the F characteristic.

[0051] Figure 11 shows the noise levels across the entire frequency range at a pressure of 0.7 MPa for silencer device 1 and the commercially available silencer. The overall noise level was 69.44 dB for silencer device 1 and 82.45 dB for the commercially available silencer. For comparison, the measurement for a diaphragm pump without a silencer attached was 104.1 dB. Therefore, silencer device 1 reduces the overall noise level by approximately 13 dB compared to the commercially available silencer, and reduces noise by approximately 35 dB compared to a pump without a silencer attached. [Example]

[0052] The silencer device of Example 2 uses a cylindrical body 5 similar to that of Example 1. A bundle of polypropylene plastic straws 28 shown in Figure 4 is used as the front capillary tube member 12, with the straws having a capillary diameter of 2.5 mm and a length of 30 mm. The rear porous metal body 8 is made up of two porous metal bodies placed one on top of the other, with both porous metal bodies having a diameter of 70 mm and a thickness of 8 mm.

[0053] In this silencer device, the thin tube member 12 disposed at the front prevents vortexes and reduces the air pressure, and the porous metal body 8 disposed at the rear diffuses the air, dispersing the air pressure and releasing it into the air. This silencer device has almost the same silencing effect as the silencer device 1 of Example 1, and the discharge resistance of high-pressure air is also almost the same. However, the manufacturing cost of this silencer device is slightly higher than that of the silencer device 1 of Example 1. [Explanation of symbols]

[0054] 1 Silencer device 2 diaphragm pump 5. Cylinder body 6 Nose 8 Porous metal body 10 Lattice section 12 Thin tube components

Claims

1. This is a hollow cylindrical device that is attached to the air outlet or discharge port of a pneumatically driven machine, and the inner diameter increases from the tip or discharge port toward the interior of the cylinder. At the rear of the cylinder, an open-cell porous metal body with a total thickness of 14 to 20 mm is held by a lattice section at the end of the cylinder. The lattice section is integral with the main body of the cylinder, and in front of the porous metal body, only thin tube members with a total length of 15 to 60 mm are densely arranged in the axial direction. Even if the high-pressure air expanded within the device is decompressed and the temperature drops, the high-pressure air comes into immediate contact with the thin tube members at the front, causing some of the air to be diffused evenly, mitigating the sudden decompression and equalizing the temperature. Furthermore, the porous metal body arranged at the rear reduces the noise generated.

2. The metal material used as the porous metal body is a chip made of a 6-20 mesh metal cutting material, which is a hypereutectic material of an Al-Si alloy, with powder of an Al-Zn-Mg alloy eutectic material attached to the surface. The chip is pressurized with a press and heated to 500-600°C by passing a high current of 6000-9000 A through it, melting only the Al-Zn-Mg alloy on the chip surface, and then the pressure is released to form a porous body, with a density of 0.8-1.5 g / cm. ３ 2. The silencer device according to claim 1, wherein the silencer device is adjusted to:

3. A silencer device as described in claim 1, wherein the cylindrical body of the silencer device consists of a front cylindrical section including a cylindrical tip section and a rear cylindrical section whose cylindrical end is formed by a lattice section, and when assembled, the two stepped sections of the front cylindrical section and the rear cylindrical section are joined and welded together.

4. 2. A silencer device according to claim 1, wherein the thin tube member in front of the porous metal body is bound entirely with aluminum foil tape or is a bundle of thin tubes made of metal, so that static electricity inside can be quickly released through the porous metal body behind.

5. 2. The silencer device according to claim 1, wherein the thin tube member in front of the porous metal body is a single-faced corrugated cardboard sheet made of plastic rolled into a cylindrical shape or a bundle of plastic straws.

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