JP2959207B2 - Blow molding method of parent-child pipe - 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 blow-molding a so-called parent-child pipe, and more particularly to a method of blow-molding a single-layer or multi-layer parent-child pipe made of resin, which is characterized by the method of forming a child pipe.

[0002]

2. Description of the Related Art In general, a liquid supply pipe used for a filler port of a gasoline tank or a spout of a barrel of beer or alcoholic beverage is a large-diameter pipe (a parent pipe) for discharging a liquid at the time of refueling or the like. ) And a small-diameter pipe (child pipe) for degassing. Usually, one end of the child pipe is connected in the middle of the parent pipe, and the parent pipe and the child pipe are integrated. This structure is generally called a parent-child pipe.

Conventionally, in order to manufacture a parent-child pipe, separately prepared large-diameter metal parent pipes and small-diameter metal child pipes are integrated by brazing, spot welding, or the like. One end of the small diameter pipe was connected to the inside of the large diameter pipe.

However, such a large-diameter pipe and a small-diameter pipe are separately made of metal, and their body (side wall) is formed.
When the parent and child pipes are made by connecting one end of the small-diameter pipe into the large-diameter pipe after brazing or spot welding, the weight is heavy because the product is made of metal. It is difficult to reduce the cost, it is corrosive because it is made of metal, and when connecting a small diameter pipe to a large diameter pipe, the metal pipe is not flexible, so the installation work is very difficult Problem.

In view of the above problems, a method of integrally manufacturing a non-metallic liquid supply pipe that is lightweight, has a small number of steps, and has good workability has been proposed by the present applicant (Japanese Patent Application No. 1-2430).
No. 52, Title of Invention "Method of Manufacturing Fluid Supply Pipe").

In the above application, a resin-made parent pipe and a small pipe are simultaneously blow-molded and integrated using a multi-head type blow molding machine, and are lightweight, have a small number of steps, and have good workability. A method for producing a supply pipe is provided. FIG. 7 of the accompanying drawings shows a parent-child pipe 126 provided by the above application. Large diameter parent pipe 103
And the small-diameter child pipe 105 are connected to the first heat-sealed part 14 during blow molding.
It is integrated by heat fusion at 0, but both pipes
103 and 105 are heat-sealed independently (not in communication) with each other. Accordingly, an opening is provided in the side wall of the parent pipe 103, and the lower end of the pipe 105 is applied to the opening with a child pipe to perform heat fusion (second heat fusion section 125), thereby forming the parent pipe 103 and the small pipe.
And 105. Reference numeral 127 denotes a bellows portion, which makes the child pipe 105 flexible so that the lower end of the child pipe 105 is easily fused to the parent pipe 103. This parent-child pipe 12
6 is a parison blow-molded product, so it is lighter than a metal parent-child pipe and has no risk of corrosion. Also,
Since the parent pipe 103 and the child pipe 105 are integrally formed, the number of manufacturing steps is reduced. Furthermore, the child pipe 105 has a bellows 127
Therefore, the work of attaching the child pipe 105 to the parent pipe 103 is also easy.

[0007]

However, in the above proposal, when the child pipe 105 is communicated with the parent pipe 103, an opening is provided in the wall surface of the parent pipe 103, and then the child pipe 105 is connected to the opening. A step of heat fusion is required. This heat fusion step requires equipment for this step. In addition, since this heat fusion step is a step after pipe molding, a heating step is naturally required. Further, a bellows portion 127 must be formed in the child pipe 105 in order to facilitate the attachment (thermal fusion) of the child pipe 105 to the parent pipe 103. In order to form the bellows portion 127, a concave and convex portion for the bellows must be provided in the mold of the blow molding machine.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an integral blow molding method for a parent-child pipe that does not require a bellows portion and does not require a heat sealing step after the pipe is formed.

[0009]

According to the present invention, which has been devised to solve the above-mentioned object, after a parison is passed through a parent cavity and a child cavity in a blow mold, a part of the cavity is communicated. While the child cavity near the downstream of the communication part is closed, air is sucked into the parison so that the parent pipe and the child pipe are integrated at a part of the side wall and the lower end of the child pipe is closed. A method for blow-molding a parent-child pipe is provided.

[0010]

Before the parison is fed into the blow mold, the parent cavity and the child cavity are made independent of each other. After the parison is passed through both cavities, a part of both cavities is communicated, and a child cavity near the downstream of the communicating portion is closed. When air is blown into the parison and blow molding is performed in this state, the parent pipe is formed independently in the parent cavity, and the child pipes are formed independently in the child cavity. At about the same time, a part of the parison also enters the communicating portion, so that the parent pipe and the child pipe are fused by the parison, and the parent pipe and the child pipe are joined and integrated at the side wall. At this time, since the child cavity near the downstream of the communication part is closed, the child pipe is formed with its lower end closed.

[0011]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a blow molding method for a parent-child pipe according to the present invention; FIG.

In this embodiment, since the parent pipe and the child pipe are bent products, the suction molding technique for bent products disclosed in Japanese Patent Publication No. 58-47337 is used.

As shown in FIGS. 1 and 2, the blow molding machine 37 has two heads (a first head 1 and a second head 2). A first parison 4 and a second parison 6 are extruded from these heads 1 and 2, respectively. The blow molding machine 37 has a structure capable of single-layer blow molding. A first blow pin 22 and a second blow pin 23 extend from lower ends of the two heads 1 and 2, respectively. Below the heads 1 and 2, a split mold assembly 39 is provided. As shown in the figure, the mold assembly 39 is composed of a first mold 7 and a second mold 8, and a convex portion is formed on a joint surface of the first mold 7 with the second mold 8. The joint surface of the second mold 8 with the first mold 7 is formed with a concave portion that engages with the convex portion.

In the mold assembly 39, a parent cavity 9 for a parent pipe and a child cavity 10 for a child pipe having a smaller diameter than the parent cavity 9 are formed. The parent cavity 9 is formed by two parent cavities each having a semicircular cross section formed on the joint surface of the first mold 7 and the second mold 8. Similarly, the child cavity 10 is formed by two child cavities each having a semicircular cross section formed on the joint surface of the first mold 7 and the second mold 8. A first upper pinch 19 and a second upper pinch 20 for closing the upper ends of the cavities 9 and 10 are provided on the top surface of the mold assembly 39 below the heads 1 and 2.

As shown in FIG. 1, the cavities 9, 1
Numerals 0 are formed so as to approach each other substantially at the center (approximately the center of the mold assembly 39). In the first approach portion 29 of the mold assembly 39, a first communication portion 34 connecting the two cavities 9, 10 is formed. The first communication hole 34 is, like the cavities 9 and 10,
Partitions are formed by grooves formed on the joining surfaces of the dies 7 and 8, respectively. Before the blow molding, the first gate valve 11 is disposed in a closed state in the first communication portion 34 to isolate (not communicate) the parent cavity 9 and the child cavity 10. The first gate valve 11 is the first actuator 1
It is configured so that it can be moved from the closed state to the open state by being moved at 4.

The cavities 9 and 10 are provided in the first approaching portion 2.
9 is formed so as to approach again below (the second approach portion 30). This second approaching portion 3 of the mold assembly 39
0, the cavities 9, 10 as in the first approaching section 29.
A second communication part 31 is formed. The second communication portion 31 is also formed by grooves formed on the joining surfaces of the molds 7 and 8 respectively. Before the blow molding, the second gate valve 12 is also disposed in the second communication portion 31 in a closed state to isolate the cavities 9 and 10. The second gate valve 12 is configured to be moved by a second actuator 15 and change from a closed state to an open state.

On the lower surface of the mold assembly 39, a lower pinch 21 for closing the lower end of the parent cavity 9 is provided. The means for closing the child cavity 10 is not provided on the lower surface of the mold assembly 39, but is provided inside the mold assembly 39 (13). Reference numeral 13 denotes a third gate valve, which is located near the downstream of the second approach portion 30 (between the second approach portion 30 and the lower surface of the mold assembly 39) as shown in FIG. It is configured to be. The third gate valve 13 is opened before blow molding, and the child cavity 10 penetrates the mold assembly 39 (FIG. 6). A blower (not shown) is provided below the mold assembly 39 for sucking the parison pushed into the cavities 9 and 10 downward.

When the parison 4 for the parent pipe is extruded from the first head 1 of the multi-head blow molding machine 37 and the parison 6 for the child pipe are respectively extruded from the second head 2, the first communication portion 34 is previously inserted into the first communication portion 34. The first gate valve 11 is closed, the second gate valve 12 is closed in the second communication portion 31, and the third gate valve 13 is open below the second approach portion 30. When the molds 7 and 8 are closed to form one mold assembly 39, the cavities 9 and 10 are made independent. In this state, the first parison 4 is extruded from the first head 1 and introduced into the parent cavity 9, and the second parison 6 is extruded from the second head 2 and introduced into the child cavity 10. At the same time, a suction force 17, 18 is applied to the parisons 4, 6 by a blower (not shown) to assist the parisons 4, 6 through the cavities 9, 10.
As a result, the parison 4 for the parent pipe passes through the parent cavity 9 and stops the blower when the parison 4 is pulled out from the lower surface of the mold assembly 39 by a predetermined length. Similarly, the parison 6 for the child pipe passes through the child cavity 10 and is pulled out from the lower surface of the mold assembly 39 by a predetermined length. When the tips of the parisons 4 and 6 are pulled out from the lower surface of the mold assembly 39 and the operation of the blowers (17 and 18) is stopped, the upper pinches 19 and 20 and the lower pinch 21 are closed.
Here, the first gate valve 11 and the second gate valve 12 are opened by the respective actuators 14 and 15, and the third gate valve 13 is closed by the actuator 16. And cavities 9,10
Blow pins 22 and 2 in parisons 4 and 6 inserted in
Blow molding is performed by blowing air from 3. Then, FIG.
As shown in the figure, the first parison 4 is pressed against the wall surface of the parent cavity 9 to become the parent pipe 3 having a predetermined shape.
On the child cavity 10 side, the second parison 6 is pressed against the wall surface of the child cavity 10 to form the child pipe 5 having a predetermined shape. At this time, a part of the parisons 4 and 6 is
31 and heat-sealed. Specifically, as shown in FIGS. 4 and 5, the first parison 4 flows into the child cavity 10 and covers a part of the side wall of the child pipe 5. Thereby, the parent pipe 3 and the child pipe 5 are integrated. Also, as shown in FIG. 6, since the vicinity of the lower end of the child cavity 10 is closed by the third gate valve 13, the lower end of the child pipe 5 is closed and formed. Therefore, when the molds 7 and 8 are opened, FIG.
The parent pipe 3 which is a large-diameter pipe and the child pipe 5 which is a small-diameter pipe as shown in FIG. Thus, the parent-child pipe 26 is obtained. In this state, the insides of the parent pipe 3 and the child pipe 5 do not communicate with each other.

Next, the parent pipe 3 and the child pipe 5 are communicated with each other in the second heat-sealed portion 25 of the parent-child pipe 26 obtained in the state shown in FIG. That is, as shown in FIG.
A hole 24 is opened at the heat-sealing portion 25 by machining to allow the parent pipe 3 and the child pipe 5 to communicate with each other.

The parent-child pipe as shown in FIG. 3 is attached to, for example, a filler port of a gasoline tank. At the time of refueling, gasoline flows through the large-diameter pipe 3, and at this time, the small-diameter pipe 5 functions as a gas vent, so that supplied gasoline flows smoothly without pulsation.

According to this embodiment, since the multi-head blow molding machine 37 and the suction molding method described in Japanese Patent Publication No. 58-47337 are used, a product with less burrs can be obtained.

The first heat-sealed portion 40 of the large-diameter pipe 3 and the small-diameter pipe 5 may be formed at a portion other than the center of the pipe. Further, two or more first heat fusion parts 40 may be provided.

In this embodiment, the blow molding machine 37 having only two heads is employed, but a blow molding machine having three or more heads may be employed. That is, the present invention can be applied to integrally blow-molding the same number of pipes as the number of heads.

As the blow molding machine 37, a blow molding machine having a structure capable of multi-layer blow molding may be employed. In this case, taking two layers as an example, for example, each pipe can be a two-layer pipe made of a normal resin and one layer made of a corrosion-resistant material.

[0025]

[Effects of the Invention] (1) The parent and child pipes can be integrally formed simultaneously.

(2) The communication process between the parent and child pipes is simplified.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a multi-head blow molding machine for performing a method according to an embodiment of the present invention.

FIG. 2 is a view taken in the direction of arrows AA in FIG. 1;

FIG. 3 is a perspective view of a parent-child pipe formed by using the blow molding machine shown in FIGS. 1 and 2;

FIG. 4 is an enlarged view of a second fused portion in FIG. 1;

5 is a view taken in the direction of arrows BB in FIG. 4;

FIG. 6 is an enlarged view of the vicinity of a third gate valve in FIG. 1;

FIG. 7 is a perspective view of a conventional parent-child pipe.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 1st head 2 2nd head 3,103 Parent pipe 4 1st parison 5,105 child pipe 6 2nd parison 7 1st die 8 2nd die 9 Parent cavity 10 Child cavity 11 First gate valve 12 Second Gate valve 13 Third gate valve 14 First actuator 15 Second actuator 16 Third actuator 17 First suction force 18 Second suction force 19 First upper pinch 20 Second upper pinch 21 Lower pinch 22 First blow pin 23 Second blow pin 24 Connection Portion Hole 25, 125 Second Heat-Fused Portion 26, 126 Parent-Child Pipe 29 First Approach Portion 30 Second Approach Portion 31 Second Communication Portion 34 First Communication Portion 37 Blow Molding Machine 39 Die Assembly 40 First Heat Fused part 127 Bellows part

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Akira Iwawaki 1 Shin-Nakahara-cho, Isogo-ku, Yokohama-shi, Kanagawa Prefecture Inside the Technical Research Laboratory, Ishikawajima-Harima Heavy Industries Co., Ltd. No. 1 Ishikawajima-Harima Heavy Industries, Ltd., Yokohama No. 2 Factory (56) References JP-A-2-243323 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) B29C 49/00-49 / 80

Claims (2)

(57) [Claims] After a parison penetrates through a parent cavity and a child cavity in a blow molding die, a part of the cavity is communicated with the parison and the child cavity near a downstream of the communication part is closed into the parison. A blow molding method of a parent-child pipe, wherein air is sucked to form a parent-child pipe in which a parent pipe and a child pipe are integrated at a part of a side wall and a lower end of the child pipe is closed. 2. The method of claim 1, wherein said parent pipe and said child pipe communicate with each other at an integral side wall thereof.