JP2554598B2 - Synthetic resin blow molding tube - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a synthetic resin blow-molded pipe which is composed of a plurality of different material parts and serves as an automobile air-conditioning duct pipe.

[0002]

2. Description of the Related Art As a synthetic resin blow-molded tube of this type, there is a rigid thin-walled plastic tube described in Japanese Utility Model Publication No. 60-27270.

[0003]

In the above-mentioned conventional one, the single parison is made of a single thermoplastic synthetic resin such as polyethylene or polypropylene, and the bendable bend portion is also made of the same material. There is a feeling that the degree of bending deformation of this bent portion is just one step away. An object of the present invention is to provide a blow molding pipe made of synthetic resin, which is a duct pipe for automobile air conditioning, which facilitates the curved deformation without reducing the pipe diameter, to the market.

[0004]

In order to solve the above-mentioned problems, the present invention comprises a single parison of at least two layers of a hard synthetic resin layer and a soft synthetic resin layer, and has at least one bent portion. The thickness of the soft synthetic resin layer in the portion is increased and the other portions are formed by increasing the thickness of the hard synthetic resin layer, and the bent portion serves as a joint portion at one end of the blow blow tube made of synthetic resin. The blow molding pipe made of synthetic resin is characterized in that it is a duct pipe for automobile air conditioning formed in the middle thereof as a bellows portion.

[0005]

EXAMPLES Next, typical examples of the present invention will be described. Example 1 In FIG. 1, at least one bent portion is formed, and the thickness ratio of the soft synthetic resin layer in this bent portion is increased, and the other portions are formed by increasing the thickness ratio of the hard synthetic resin layer. The bent portion is formed as a joint portion at one end of a synthetic resin blow molding tube and as a bellows portion in the middle thereof, and B is a single hard synthetic resin (for example, HD.
PE resin) G layer and soft synthetic resin (eg LDPE resin)
A duct pipe for an air conditioner for an automobile, which is composed of a blow molding pipe made of a synthetic resin made of a two-layer parison with an F layer,
The bellows portion J has an intermediate portion and a joint portion T with a thread groove R at one end portion thereof. The bellows portion J and the joint portion T are formed by increasing the thickness ratio of the soft synthetic resin F layer, and the other portions are formed by increasing the thickness ratio of the hard synthetic resin G layer (see FIG. 2).

Next, an example of the manufacturing apparatus and the manufacturing method of the duct pipe B will be described with reference to FIG. In FIG. 4, A shows the entire blow molding machine as a hollow molded article manufacturing apparatus, and the blow molding die 10 is provided with a single parison discharge port 11 similarly to the known one. Double resin supply paths 12 and 13 communicating with the
Are provided in the molding die 10. Further, accumulator type injection machines 14 and 15 are connected to the resin supply paths 12 and 13, respectively, and molten resin is sent to the resin accumulator chambers 16 and 17 of the accumulator type injection machines 14 and 15, respectively. Extruders 18 and 19 are connected to the accumulator type injection machines 14 and 15, respectively. In order to blow mold the duct pipe B with the flexible bellows portion J and the joint portion T shown in FIG. 1 by the blow molding machine A, one of the resin supply passages 12 and 13 is It is for a soft synthetic resin (for example, LDPE resin) F that is used in a large amount for forming the bellows portion J and the joint portion T, and the other resin supply path 13 is a hard synthetic resin (for example, H
DPE resin) Used for G. The extruder 18, 1
The corresponding synthetic resin is supplied to the extruding screws 20 and 21 of 9 and melts the soft synthetic resin F to the resin accumulator chamber 1 of the accumulator type injection machine 14 on the side of the one resin supply passage 12 side.
6, a predetermined amount is extruded and temporarily retained, and the plunger 2
Maintain 2 in the retracted position.

On the other hand, the molten hard synthetic resin G is extruded into the resin accumulator chamber 17 of the accumulator type injection machine 15 on the side of the other resin supply passage 13 and the desired amount of the hard synthetic resin G is retained therein. Die 10
The hard synthetic resin G in the molten state in the resin accumulator chamber 17 is extruded from the parison discharge port 11 through the resin supply passage 13 to produce the hard synthetic resin G layer of the duct pipe B to be manufactured. A parison P ₁ having a predetermined size corresponding to a portion having a higher thickness ratio of ₁ is extruded from the molding die 10. At this time, although the soft synthetic resin F temporarily staying in the resin accumulation chamber 16 is also thin, it is extruded from the parison discharge port 11 and the parison P ₁
The parison P ₁ is composed of two layers of a soft synthetic resin F layer and a hard synthetic resin G layer.

Next, in order to push out the parison P ₂ for the flexible bellows portion J and the joint portion T, the plunger 23 is retracted and the screw 21 of the corresponding extruder 19 is rotated at a low speed, A predetermined amount of the hard molten resin G in a molten state extruded from the extruder 19 is temporarily retained in the resin accumulator chamber 17, and the parison P from the parison discharge port 11 of the molding die 10 is retained.
_One extrusion-type injection machine 14 is operated at the same time as the extrusion of _{No. 1} is stopped, and the plunger 22 is moved to the molding die 1
The parison discharge port 11 is advanced through the resin supply passage 12 by advancing the plunger 22 by a predetermined dimension.
The molten soft synthetic resin F in the resin accumulator chamber 16 is extruded by a predetermined amount, and a parison P ₂ having a predetermined size corresponding to the bellows portion J and the joint portion T is connected to the parison P ₁ as a unit and the parison discharge port 11 is integrated. More extruded. The total thickness of the parison P _{2 is the same as} the total thickness of the parison P ₁ , but the thickness ratio of the soft synthetic resin F layer in the parison P ₂ is higher.
Although the hard synthetic resin G temporarily retained in the resin accumulation chamber 17 is also thin, it is extruded from the parison discharge port 11 to form a part of the parison P ₂ , and the parison P ₂ also forms the parison P _1. Similarly, it is composed of two layers of a soft synthetic resin F layer and a hard synthetic resin G layer. By repeating the above-mentioned operation, a parison P ₁ made of a hard synthetic resin and a parison P ₂ made of a soft synthetic resin are alternately connected in series in series to form a single parison P which is opened into a molding die ( (Not shown), the mold is clamped, and the molding die 11
From the above, air is blown into the parison P as usual to increase the thickness ratio of the soft synthetic resin F layer in the bellows portion J and the joint portion T, and increase the thickness ratio of the hard synthetic resin G layer in the other portions. The duct pipe B for automobile air conditioning is blow-molded.

Embodiment 2 (see FIG. 3) In this embodiment, a gas barrier resin layer G ₀ is further formed on the entire inner peripheral surface of the duct pipe B of Embodiment 1 to form an automobile air conditioning duct pipe B ₂ . .

[0010]

According to the blow molding pipe made of synthetic resin of the present invention, the bending portion of the blow molding pipe made of a single parison is used as a duct pipe for automobile air conditioning. Since it is molded by increasing the thickness ratio and increasing the thickness ratio of the hard synthetic resin layer in other parts, for example, the positions of both ends of the blow molded pipe are largely three-dimensionally decentered during assembly, and piping is performed. Even if it is necessary, the bent portion is easier to bend than other portions, and the blow molding pipe made of synthetic resin can be attached and piped in a sufficiently curved state. Moreover, since it is composed of at least the above-mentioned two layers of parison, it is possible to perform blow molding in a state where both the hard and soft synthetic resins of the bent portion and other portions are connected in series.

Further, the bellows portion and the joint portion, which are the bent portions of the automobile air-conditioning duct tube, are formed by increasing the ratio of the thickness of the soft synthetic resin layer, so that, for example, at the time of assembling, the positions of both ends of the blow-molded tube can be greatly increased. Even when it is necessary to assemble and pipe the core by deviating it from the center, the bent portions of the bellows portion and the joint portion are more easily bent than the other portions, and the blow molding pipe made of the synthetic resin is sufficiently curved in a bent state. Can be installed and piped.

Effects Specific to the Embodiment In the second embodiment, as described above, the gas barrier resin layer G ₀ is further formed on the entire inner peripheral surface of the automobile air-conditioning duct pipe B ₂ as described above, and this description is made. The desired air can be sucked through the duct tube B ₂ without leaking to the outside.

Next, specific examples of resin combinations will be shown. a) In case of two kinds and two layers <Refer to FIG. 2> Inner layer Outer layer 1) LDPE HDPE 2) EVA HDPE b) In case of three kinds and three layers <Refer to FIG. 3> Inner layer Intermediate layer Outer layer Gas barrier resin Hard PP Soft PP

[Brief description of drawings]

FIG. 1 is a perspective view of a duct pipe according to a first embodiment.

FIG. 2 is a cross-sectional view showing a resin layer of a bellows portion and a joint portion of the duct pipe of FIG.

FIG. 3 is a sectional view similar to FIG. 1 of the second embodiment.

FIG. 4 is a schematic view of an apparatus for manufacturing the duct tube shown in FIG.

[Explanation of symbols]

 A Manufacturing Equipment 14, 15 Accumulator Type Injection Machine B Automotive Air Conditioning Duct Pipe J Bellows Pipe T Joint Pipe

Claims (1)

(57) [Claims] 1. A single parison composed of at least two layers of a hard synthetic resin layer and a soft synthetic resin layer, having at least one bent portion, and increasing the thickness ratio of the soft synthetic resin layer at this bent portion. A part is formed by increasing the thickness ratio of the hard synthetic resin layer, and the bent portion is formed as a joint portion at one end of a synthetic resin blow molding pipe and as a bellows portion in the middle thereof. A blow molding pipe made of synthetic resin, characterized by being used as a duct pipe for use.