JP3469119B2 - Manufacturing method of intake pipe with silencing function and mold used for it - 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 of manufacturing an intake pipe with a sound deadening function by hollow molding (blow molding) and a molding die used therefor.

[0002]

2. Description of the Related Art Conventionally, as a method for manufacturing an intake pipe of this type, a technique disclosed in, for example, Japanese Patent Laid-Open No. 10-238426 is known. In this technique, an intake pipe is formed by blow-molding a multi-layered parison set in the cavity of a blow mold according to the shape of the cavity. The molded intake pipe is composed of a large-diameter muffling section (expanding section) and small-diameter tube sections (main body sections) located on both sides of the muffler section, and the inner surface of which is formed by a foam layer having irregularities ing.

Therefore, the intake pipe of this structure has an intake pulsation (air pressure
It has a function as an expansion type that reduces the fluctuation of the flow velocity) by an expansion / contraction action due to a change in the cross section of the intake passage, and a function as a sound absorbing type that uses the foam layer as a sound absorbing material. As the intake pipe with a sound deadening function, a type called a resonance type is often used in addition to an expansion type and a sound absorbing type, and an example thereof is shown in FIGS. The resonance type intake pipe shown in these drawings is provided with a box-shaped resonator 70 (resonator) that resonates at a specific frequency in the middle of the passage.

The intake pipe shown in FIG. 7 is a rubber tube 50.
In the example using, a connector 52 is integrally formed between both ends of the tube 50. The connector 52 is connected to the opening 72 of the resonator 70 by a clamp 54 so that the tube 50 and the resonator 70 communicate with each other.

The intake pipe shown in FIG. 8 is an example in which a resin tube 60 is used, and a connector 62 is insert-molded in the tube 60 at the time of molding. The opening 72 of the resonator 70 having substantially the same shape as that described above is joined to the insert connector 62 by welding so that the tube 60 and the resonator 70 communicate with each other. In the state where the connector 62 is still insert-molded, the inside of the connector 62 is closed by the molding resin of the tube 60 as shown by the phantom line in FIG. 8, so it is necessary to scrape it off.

[0006]

Although the intake pipe disclosed in the above publication has a sound deadening performance as an expansion type and a sound absorbing type, the parison for molding the same has a multilayer structure having a foaming agent-containing layer. It is necessary to increase the cost of the intake pipe. In addition, the resonance type intake pipes shown in FIGS. 7 and 8 have only the silencing performance with respect to the intake sound having a specific resonance frequency. And these intake pipes
Since the tubes 50 and 60 and the resonator 70 are individually molded and connected by the means as described above, the manufacturing process thereof is complicated and the cost is increased.

The present invention is intended to solve the above-mentioned problems, and an object thereof is to make it possible to provide an economical intake pipe which is excellent in silencing function for intake noise in a wide frequency range by simple manufacturing. is there.

[0008]

SUMMARY OF THE INVENTION The present invention is to achieve the above object. The invention according to claim 1 is a method of manufacturing an intake pipe with a sound deadening function by hollow molding, which comprises a cavity of a molding die. By blowing air into the parison set inside, the parison is brought into close contact with the inner surface of the cavity, and the muffling section has a large volume of internal space, and the tube section that communicates with the internal space of the muffling section on both sides. And are integrally hollow molded. After that, at least one of the tube portions is pushed into the sound deadening portion along the axis thereof, so that one end side of the tube portion is projected into the internal space of the sound deadening portion.

According to the present invention, the sound deadening portion forming the intake pipe and both tube portions communicating with the inner space are integrally molded, and the one end side of the tube portion is projected into the inner space of the sound deadening portion. Easy to implement. The molded intake pipe has an extended silencer performance with a silencer and a tube, as well as an interference-type silencer in which the portion of the silencer protruding into the internal space interferes with the flow of intake air to reduce sound. Demonstrate performance. Therefore, the silencing performance for sounds in a wide frequency range can be obtained and the cost can be reduced.

According to a second aspect of the present invention, there is provided a molding die for use in the method of manufacturing an intake pipe with a sound deadening function according to the first aspect, wherein the mold has a shape corresponding to the outer shape of each of the sound deadening part and both tube parts. Equipped with tea. A cavity corresponding to the outer shape of at least one of the tube portions is configured by a cylindrical slide block that is separate from the other portions, and this slide block is slidable in the direction along the axis thereof. . By using this mold, not only integral molding of the muffling section and both tube sections communicating with the inner space but also molding in which at least one tube section is pushed into the inner space of the muffling section can be easily performed. .

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below. FIG. 1 is a cross-sectional view of a state in which a resin parison 20 is set inside a molding die 10 (blow die) composed of an upper die and a lower die and the die is clamped. The parison 2 at this time
The inside of 0 is in a pre-blow state in which an appropriate amount of air is blown in advance. Inside the molding die 10, there is a large-volume cavity 12 located approximately in the center thereof.
And small-volume cavities 13 and 1 located on both sides
4 are formed.

Each of the cavities 12, 13, 14 has a cylindrical inner peripheral surface. Further, the cavity 13 is constituted by a slide block 16, and the slide block 16 is formed separately from the other parts of the molding die 10. Moreover, the slide block 16 can be slid to the right or the return direction from the position shown in FIG. 1 by some operating means. The slide block 16 is also divided into an upper mold side and a lower mold side, but when the mold is clamped, the overall shape of the slide block 16 is cylindrical, and the thickness of the outer peripheral portion of the cavity 13 maintains its strength. It is set thin within the range that can be done.

In hollow molding (blow molding) of the intake pipe, air is blown into the parison 20 from the blowing nozzle 18 to inflate it in the mold clamping state of the molding die 10 shown in FIG. By this, parison 20
2 adheres to the inner surfaces of the cavities 12, 13, 14 as shown in FIG. 2, and a muffling section 30 having a large volume of internal space 32 is formed in the cavity 12,
Tube portions 34 and 36 are molded in 3 and 14, respectively. Note that the tube portion 36 has the cavity 1
The bellows portion 37 is formed based on the shape of No. 4.

Subsequently, as shown in FIG. 3, by sliding the slide block 16 toward the inside of the cavity 12, the tube portion 34 is pushed into the muffling portion 30. In parallel with this, by blowing air again into the parison 20 from the blowing nozzle 18, the shape of the pushed tube portion 34 and the shape of the side wall portion of the sound deadening portion 30 are adjusted as shown in FIG. As a result, a projecting portion 35 mainly having one end side of the tube portion 34 is formed in the internal space 32 of the muffling section 30. Since the wall thickness of the outer peripheral portion of the cavity 13 in the slide block 16 is thin as described above, the gap between the outer peripheral portion of the tube portion 34 and the side wall portion of the muffling portion 30 in the protruding portion 35 is small. is there.

Next, as shown in FIG. 5, the slide block 16 is slid in the return direction, and the final air is blown into the parison 20 from the blowing nozzle 18. As a result, the gap between the overlapping portions of the protruding portion 35 is eliminated, and the protruding portion 3
5 shapes are arranged.

Through the above molding process, the muffling section 30 and the tube sections 34 communicating with the inner space 32 on both sides thereof,
36 is integrally hollow-molded with one tube portion 3
The protruding portion 3 located in the internal space 32 by the one end side of
5 is molded. Therefore, the mold 10 is opened to take out the molded product from the inside, and the tip portions of both tube portions 34 and 36 are cut. As a result, the intake pipe with a sound deadening function shown in FIG. 6 can be obtained.

The intake pipe includes a muffling section 30 and a tube section 3.
4 and 36 have a sound-muffling performance as an expansion type in which a part of the intake passage is rapidly expanded, and an interference in which the protruding portion 35 of the internal space 32 interferes with the flow of intake air to reduce sound. Has muffling performance of the mold. Therefore, by simple molding, an intake pipe having a sound deadening performance for sounds in a wide frequency range can be obtained. The tube part 3
The bellows portion 37 of 6 serves to absorb the vibration generated between the engine and the body when the intake pipe is used in a vehicle, and is unnecessary depending on the place of use of the intake pipe.

Although the drawings show the case where only the cavity 13 is formed by the slide block 16 and the protruding portion 35 is formed by the one tube portion 34, the cavity 14 is also formed by the slide block and the other portion is formed. The end portion of the tube portion 36 may be pushed into the muffling portion 30 to form a protruding portion. In this way, the muffling section 3
When the protruding portions are provided on both sides of the inner space 32 at 0, even if the respective protruding amounts are set to about half of the protruding portion 35 shown in FIG. 6, almost the same silencing performance can be obtained.

As described above, according to the method for manufacturing the intake pipe of the present embodiment, the intake pipe having an excellent sound deadening function can be easily manufactured by hollow molding (blow molding).

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a clamped state of a molding die.

FIG. 2 is a cross-sectional view showing an air blowing step.

FIG. 3 is a sectional view showing a sliding step of a slide block.

FIG. 4 is a cross-sectional view showing a second air blowing step.

FIG. 5 is a sectional view showing a return slide process of the slide block.

FIG. 6 is a sectional view of the completed intake pipe.

FIG. 7 is a cross-sectional view showing a conventional rubber intake pipe.

FIG. 8 is a cross-sectional view showing a conventional resin intake pipe.

[Explanation of symbols]

10 Mold 12, 13, 14 cavity 16 slide blocks 20 parison 30 silencer 32 internal space 34, 36 tube part

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Claims (2)

(57) [Claims] 1. A method of manufacturing an intake pipe with a sound deadening function by hollow molding, wherein air is blown into a parison set in a cavity of a molding die to bring the parison into close contact with the inner surface of the cavity. After integrally hollow molding the sound deadening part having a large volume internal space and the tube parts communicating with the inner space of the sound deadening part on both sides,
A method for manufacturing an intake pipe with a sound deadening function, characterized in that at least one tube portion is pushed into the sound deadening portion along the axis thereof to project one end side of the tube portion into the internal space of the sound deadening portion. 2. A molding die used in the method for manufacturing an intake pipe with a sound deadening function according to claim 1, comprising a cavity having a shape corresponding to the outer shape of each of the sound deadening part and both tube parts, The cavity corresponding to the outer shape of the tube portion is composed of a cylindrical slide block that is separate from the other portions, and this slide block is assembled so as to be slidable in the direction along its axis. Mold.