JP3130760B2 - Muffler and manufacturing method thereof - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a muffler for reducing noise generated by a pneumatic device.

[0002]

2. Description of the Related Art In recent years, pneumatic devices such as air cylinders have been used as actuators constituting various industrial robots. By the way, when pressurized air, which is a driving fluid for the air cylinder, is directly discharged into the air from the air cylinder, a loud noise is generated, which may deteriorate the surrounding working environment. For this reason, noise reduction measures such as discharging pressurized air through a silencer are often taken in the air cylinder.

As a silencer of this kind, for example,
The one disclosed in Japanese Patent Publication No. 8806 is conventionally known. The disclosed silencer includes a case in which a connection port to a pneumatic device is opened, and a silencer provided in the case. The case has a plurality of exhaust ports, and is formed of a thermoplastic synthetic resin. On the other hand, the sound deadening material is formed of a powdery sintered body having a hollow bottom having fine ventilation holes. When manufacturing such a silencer, first, by sintering metal powder or resin powder,
The silencing material must be formed in advance. After this, the silencing material is placed in a mold for molding the case. And
In this state, the molten thermoplastic synthetic resin is discharged into the mold. As a result, the case is integrally fixed to the muffler while the case surrounds the muffler.

[0004]

By the way, it is known that the silencing effect of the silencer generally increases as the outer diameter of the silencing material increases (in other words, the thickness of the silencing material increases). However, in the case of the conventional silencer, since the case surrounds the silencer, the silencer tends to be thinner by that much. Therefore, there is a disadvantage that when the thickness of the silencing material is increased to improve the silencing effect, the silencer becomes large. Of course, if priority is given to miniaturization of the silencer, it is impossible to improve the silencing effect. Further, with the above configuration, there is also a disadvantage that the air that is going to flow to the outside is partially blocked by the case, so that a large effective cross-sectional area for silencing cannot be ensured.

Further, in order to manufacture this silencer,
It is necessary to go through at least two molding steps and to use a plurality of types of materials having different properties. Therefore, there is a need for a silencer that requires less time and effort to manufacture and has a lower cost.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide a silencer that can be easily and reliably provided.
It can be manufactured and has a better noise reduction effect
It is an object of the present invention to provide a method for manufacturing a muffler capable of manufacturing a muffler .

[0007]

[0008]

[0009]

[0010]

Means for Solving the Problems To solve the above problems,
In order, in the invention according to claim 1, a first step of filling the molding material into the mold, a second step of forming a shaped body by adding a pressing force to the molding material, the A third step of heating and pressurizing the molded body and firing the molded body, wherein at the time of the third step, a portion of the molded body that is to be a bottom of the sound deadening material later in the molded body, The gist of the present invention is a method for manufacturing a muffler for heating a portion higher than other portions to densify the portion.

[0011]

[0012]

[0013]

According to the invention described in [action] claim 1, it is possible to easily and reliably produce the muffler, it is possible to produce a better silencer silencing effect.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will now be described with reference to FIGS.
This will be described in detail with reference to FIG. As shown in FIGS. 1 and 2, the silencer 2 constituting the silencer 1 of the present embodiment is made of a hollow resin powder sintered body having fine continuous pores.
The silencer 2 has a substantially cylindrical shape as a whole, and one end surface thereof is a bottom 3. The area inside the silencer 2 is an internal space S1 into which pressurized air discharged from a pneumatic device such as an air cylinder flows. Noise reduction material 2
The other end face is integrally provided with a cylindrical opening projection 4 which can be connected to the pneumatic device side. The outer diameter of the opening projection 4 is slightly smaller than the outer diameter of the silencer 2. The internal space S1 of the silencer 2 communicates with the external area through the communication port 5 of the opening projection 4. A male screw thread 6 is integrally provided on the outer wall surface of the opening projection 4 as a connection locking structure when connecting to a pneumatic device.

This silencer 1 having a silencer 2, an opening protrusion 4 and a male thread 6 is used for firing a compact M1 molded using a material obtained by adding inorganic fibers to a resin powder. Obtained by In this embodiment, a mixture of a polypropylene resin powder having a particle size of 10 μm to 200 μm and a polyethylene resin powder having a particle size of 10 μm to 200 μm is used as the resin powder. In this mixture, the powder of the polypropylene resin and the polyethylene resin are present in substantially equal amounts. Since the polypropylene resin has an effect of reducing sink marks of the sintered body, the blending ratio may be increased as necessary. Further, the addition of the inorganic fiber leads to an improvement in the mechanical strength of the muffler 1 and an improvement in the muffling effect.

The average particle size of the resin powder used to form the opening projections 4 and the male threads 6 is within the above range, compared to the average particle size of the resin powder used to form the sound deadening material 2. It is desirable that the setting be made smaller. This is because if the average particle size is small, the obtained sintered body becomes relatively dense, and the mechanical strength of the portion increases accordingly. That is, it is desirable that a mechanical strength higher than that of the silencer 2 is secured in the portion of the opening projection 4 and the male screw thread 6 where stress or the like is easily applied. Therefore, the average particle size of the resin powder used to form the opening projections 4 and the male screw threads 6 is preferably set to about 10 μm to 30 μm. On the other hand, the average particle size of the resin powder used for forming the silencing material 2 is preferably set to be larger than that and about 70 μm to 100 μm.

The inorganic fiber has an average fiber length of 5
Glass fibers of 0 μm to 150 μm are used. The amount of the glass fiber added to the mixture of the resin powder is preferably in the range of 10% by weight to 20% by weight. If the ratio is outside the above range, the mechanical strength and the noise reduction effect may not be sufficiently improved.

Next, a procedure for manufacturing the silencer 1 of the embodiment will be described with reference to FIG. FIG. 3A shows molds 7 and 7a used when manufacturing the silencer 1. Molding space S2 in relatively large mold 7
The lower half is a first forming area 8 for forming the opening projection 4 and the male screw thread 6, and the upper half is a second forming area 9 for forming the silencer 2. I have. At the center of the molding space S2, a columnar core 10 protrudes to form the internal space S1 and the communication port 5. Also,
On the upper part of the large mold 7, a relatively small mold 7a
Are arranged (see FIG. 3 (c)).

In the present embodiment, a first molding material 11 for forming the opening projection 4 and the male thread 6 and a second molding material 12 for forming the silencer 2 are used. . The types of compositions contained in the two molding materials 11 and 12 are the same. However, the average particle size of the resin powder in both molding materials 11 and 12 is slightly different. Specifically, as the first molding material 11, a mixture of a polypropylene resin powder having an average particle diameter of 10 μm and a polyethylene resin is used. As the second molding material 12, a polypropylene resin contained in the first molding material 11 in which the average particle size is changed to 100 μm is used. In addition, both of these mixtures have an average fiber length of 60 μm.
Of glass fiber is added by 15% by weight.

As shown in FIG. 3B, first, the first molding material 11 is filled until the first molding region 8 is filled. Next, as shown in FIG. 3C, the second molding material 12 is filled until the second molding region 9 is filled. Next, pressure is applied to the molding materials 11 and 12 from above the molding die 7 to hold the molding materials 11 and 12 in a predetermined shape. The compact M1 is baked by heating and pressurizing the compact M1 obtained in this manner while being inserted into the molds 7, 7a. At this time, the portion in contact with the molding die 7a (that is,
The outer surface of the part which will later become the bottom 3) is heated to a higher temperature than the other parts. The reason is that the continuous pores are sealed by densifying the portion. Such a surface densification treatment further improves the noise reduction effect of the noise reduction device 1.

As shown in FIG. 2, the opening projection 4 of the muffler 1 manufactured as described above is screwed into a female screw hole 14 formed in the air discharging portion 13 to thereby discharge the air. The part 13 is locked. The pressurized air discharged from the air discharge portion 13 flows into the internal space S1 of the sound deadening material 2 through the communication port 5 of the opening projection 4. The pressurized air that has reached the internal space S1 tries to escape from the inner peripheral surface to the outer peripheral surface of the silencer 2 by further passing through the continuous pores. At this time, silencing of the pressurized air is achieved. And
Finally, the pressurized air is discharged from the entire peripheral surface of the silencer 1 to the outside.

Now, in the silencer 1 of this embodiment, the silencer 2
In this case, the opening projection 4 and the male screw thread 6 are integrally provided. Therefore, unlike a conventional product having a configuration in which the silencer 2 is surrounded by a case, pressurized air is released from the entire peripheral surface of the silencer 2. Therefore, the pressurized air flowing to the outside is not blocked by the case. Further, in the case of the present embodiment in which no case is used, the silencing material 2 can be made thick without increasing the size of the whole, so that the silencer 1 has a large effective cross-sectional area for silencing. Becomes possible. Further, it is also possible to reduce the size of the muffler 1 without deteriorating the muffling performance.

In this embodiment, although two types of molding materials 11 and 12 are used, the compositions of both molding materials 11 and 12 are equal except for the average particle diameter of the resin powder. Further, even if such molding materials 11 and 12 are used,
According to the manufacturing method of the present embodiment, the silencer 1 can be easily and reliably obtained without performing the molding step twice. For this reason, the number of manufacturing steps can be reduced as compared with the related art, and the cost of the silencer 1 can be reduced. Of course,
Since it is manufactured using the same kind of material, there is an advantage that the number of parts is small. Furthermore, since the silencer 1 is basically made of resin, it is excellent in moldability, lightness, cost, and the like as compared with those made of metal or ceramics.

In the case of this embodiment in which the connection locking structure is a male screw thread 6, the opening projection 4 can be screwed into the female screw hole 14 of the air discharge portion 13. With such a structure, attachment and detachment of the silencer 1 becomes extremely simple. In addition, the opening protrusion 4 and the male screw thread 6 of the silencer 1
A relatively higher mechanical strength is ensured. Therefore, destruction or the like hardly occurs in the portion.

The present invention can be modified, for example, as follows. (1) As in the silencer 15 of another example 1 shown in FIG.
May be formed as a connection locking structure. FIG.
As in the silencer 17 of another example 2 shown in FIG. 1, one annular groove 18 having a semicircular cross section surrounding the opening projection 4 may be formed as a locking structure for connection. Of course, the connection locking structure
The present invention is not limited to only the shapes as in the embodiment and other examples 1 and 2.

(2) The inorganic fibers added to the mixture of resin powders are not limited to glass fibers, but may be other inorganic fibers such as ceramic fibers. It is also possible to select a nylon resin powder or the like as the resin powder.

(3) The mufflers 1, 15 and 17 are not limited to those made of a resin powder sintered body, but may be made of a metal powder sintered body or a ceramic powder sintered body. (4) The muffler 1 can be manufactured by a method other than the method exemplified in the embodiment. For example, the opening projection 4 and the connection locking structure may be formed by grinding a hollow sintered body.

(5) The muffler 1,
15, 17 may be manufactured. First, a molding M1 is produced using the molding die 7. Next, the molding M1 is placed in the molding die 7.
Is held, and the compact M1 is baked while applying a centrifugal force about the center axis of the compact M1 as the center of rotation. According to such a manufacturing method, a small resin powder can be unevenly distributed on the outer peripheral surface of the hollow sintered body and a large resin powder can be unevenly distributed on the inner peripheral surface side by the action of the centrifugal force. Therefore, the continuous pores of the sintered body become smaller as going from the inner peripheral surface to the outer peripheral surface.

Here, in addition to the technical ideas described in the claims, the technical ideas grasped by the above-described embodiment and other examples are listed below together with their effects. (1) A molding space divided into a first molding region for forming an opening projection and a connection locking structure, a second molding region for forming a sound deadening material, and a center of the molding space. A mold for manufacturing a muffler according to any one of claims 1 to 5, comprising a core protruding from the portion. When the mold having such a configuration is used, the muffler of the present invention can be easily and reliably manufactured.

[0030]

[0031]

The technical terms used in the present specification are defined as follows. "Sintered body: In addition to a resin powder sintered body, it also includes, for example, a metal powder sintered body and a ceramic powder sintered body."

[0033]

As described in detail above, according to the first to fifth aspects of the present invention, there is provided a muffler capable of achieving a low cost and an improved muffling effect without increasing the size. be able to. According to the second aspect of the present invention, it is possible to provide a muffler that can be easily attached and detached. According to the third aspect of the present invention, it is possible to provide a muffler having more excellent mechanical strength and muffling effect. According to the fourth aspect of the present invention, it is possible to provide a muffler having even more excellent mechanical strength.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a muffler according to an embodiment.

FIG. 2 is a cross-sectional view of the muffler of FIG.

FIGS. 3A to 3C are cross-sectional views illustrating a procedure for manufacturing the silencer of FIG.

FIG. 4 is a perspective view showing a muffler of another example 1.

FIG. 5 is a perspective view showing a muffler of another example 2.

[Explanation of symbols]

2 ... Muffling material, 4 ... Opening protrusion, 6 ... Male thread as connection locking structure, 16 ... Ring ridge as connection locking structure, 18 ... Ring groove as connection locking structure, 1,15,
17 ... silencer, M1 ... molded body.

Claims (1)

(57) [Claims] 1. A first step and a second step and, the molded body heat and pressure to form a molded body by adding a pressing force to the molding material filling the molding material into the mold And baking at a temperature higher than other parts of the molded body to be a bottom of the muffler in the third step. A method for producing a silencer in which the part is heated to make the part dense.