JPH058286A - Manufacture of resin hose - Google Patents

Abstract

PURPOSE:To suppress an increase in the number of manufacturing processes accompanied by the formation of a branch part and to accurately form the branch part into a predetermined shape and dimension in the blow molding of a hose having such a form that the branch part is provided to the hose main body. CONSTITUTION:In a hose 10 having such a form that a branch part 16 extends from a hose main body 12, at least the main part 11 of the hose main body 12 is formed by the blow molding of a thermoplastic resin and, in such a state that the blow molded product is set to an injection mold, the branch part 16 is subjected to injection molding to be unified with the hose main body 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a resin hose suitable for use as an air duct hose, a filler hose, etc. for automobiles.

[0002]

BACKGROUND OF THE INVENTION For example, air duct hoses for automobiles,
In a filler hose or the like, it has recently been considered to use a resin hose instead of a rubber hose, and it has been actually used.

This resin hose has a smaller specific gravity and can be made lighter than a rubber hose, that one having a soft portion and a hard portion can be formed as an integrally molded product, and the design of the shape, etc. It has advantages such as high flexibility.

Here, the fact that the one having a soft portion and the hard portion can be formed as an integrally molded product means the following. For example, in the case of a rubber hose, it is difficult to configure the soft part and the hard part as an integrated product. In this case, the part requiring hardness is composed of a metal pipe, and other flexibility is required. While this is done by using rubber hoses for parts and assembling them together, in the case of resin hoses, while hard resin materials are used for parts that require hardness, softness is required. A soft material is used for the portion to be hardened, and the hard portion and the soft portion can be integrally formed by using these materials at the time of molding the hose. Thus, if the soft portion and the hard portion can be integrally formed as described above, the number of parts can be reduced and the cost can be reduced.

In the case of a rubber hose, which has a high degree of freedom in designing, for example, when the rubber hose has a flat cross section, the same portion is easily deformed when a negative pressure is applied. In this case, the use of a hard material means that even a flat shape can sufficiently withstand such a negative pressure, which means that there are few restrictions on the shape.

By the way, in the case of such a resin hose, a blow molding method is preferably adopted as the molding method.
In this blow molding method, generally, a cylindrical and bag-shaped parison is inflated by blowing air so that the parison is brought into close contact with the inner surface of the molding die and is molded into a predetermined shape. Although it can be molded accurately,
Since the inner surface is molded in a free state, it is unavoidable that the shape and dimensional accuracy deteriorate.

However, in the hose, there is a case where it is necessary to fit a mating member such as a metal pipe into the inside of the longitudinal end portion of the hose to join the hose and to secure the sealing property of the joining portion at that time. In such a case, if the shape and dimensional accuracy of the inner surface of the hose end are poor, that is, if the inner diameter and thickness of the hose end are uneven, the wall thickness is uneven, or the inner surface is uneven, the mating member It is not possible to secure sufficient sealing performance at the joint.

Therefore, in the case of such a resin hose formed by blow molding, the inner surface of the end portion is polished and finished into a predetermined shape and size.

However, such polishing not only increases the hose manufacturing process, but also leaves polishing powder on the processed portion and its periphery. For this reason, a cleaning step for removing the polishing powder is also required, and the number of steps in the hose manufacturing is increased and the cost is increased.

Therefore, the inventor of the present invention blow-molds a thermoplastic resin to form a main part of a hose body, sets the main part in an injection-molding mold, and in that state, injects an end part for connection with a mating member. The method of manufacturing a resin hose, which is characterized in that the resin hose is molded and integrally joined to the main part, was invented, and the above patent application (Japanese Patent Application No. 3-39145)
No.).

FIG. 4 shows an embodiment of the present invention. In this embodiment, a thermoplastic resin is blow-molded to form the main portion 100.
Then, this is set in a molding die 102 for injection molding, a material is injected into the cavity of the molding die 102, and an end portion 104 for connection with a mating member is molded and simultaneously integrated with the main portion 100. I have to.

By the way, in the case of the above air duct hose,
Many of them have a branch part for introducing blow-by gas from the engine in the middle of the hose body, and some of the filler hoses also have a branch part for degassing.

When the hose body is manufactured by blow molding, these branch portions are generally provided as follows. That is, as shown in FIG. 5A, a portion to be a branch portion (hereinafter simply referred to as a branch portion) 106 is injection-molded in advance and set in a blow mold, and in this state, the hose body The tubular parison for use is inserted into the blow molding die and inflated by blowing air so that it closely adheres to the inner surface of the molding die, whereby the hose body 108 is molded and at the same time the branch portion is integrally joined thereto ((B)). reference).

[0014]

In this case, however, as shown in (C), after the blow molding of the hose body 108, the hole corresponding to the branch portion must be drilled, which is a troublesome process. In addition, the same problem as in the case where the hose body including the connecting end portion is blow-molded occurs.

That is, when such a hole forming process is performed after the blow molding, not only burrs may remain after the hole forming, but also shavings remain on the processed part and its peripheral part.

Therefore, a separate cleaning step is required to remove the shavings, and the hose manufacturing process is further increased, resulting in an increase in cost.

In addition to this, in the above method, the hose body and the branch portion may not be sufficiently welded, or in some cases, the welding may be insufficient.

In this method, the hose body and the branch portion are welded by utilizing the residual heat of the parison, but in many cases, the residual heat of the parison is not sufficient to weld the hose body and the branch portion, and particularly, If the branch portion and the hose body are made of different materials, insufficient welding tends to occur. If the welding is insufficient, it is difficult to adopt this method.

[0019]

The present invention has been made to solve the above problems, and its gist is at least the main portion of the hose body of a hose in which a branch portion extends from the hose body. Is formed by blow molding of a thermoplastic resin, and while the blow molded product is set in a mold for injection molding, the branch portion is injection molded and integrated with the hose body.

[Operation and Effect of the Invention] As described above, according to the present invention, the hose body is blow-molded, and then the branch portion is injection-molded while the hose body is set in the molding die. Prior to the above, it is possible to preliminarily form the portion corresponding to the branch portion of the hose body into the opening shape.

In the above-mentioned method, that is, in the method in which the branch portion is injection-molded in advance and then the hose body is blow-molded and at the same time integrated with the branch portion, it is inevitable that the punching process is required after the molding. According to the method (1), it is possible to form a corresponding portion of the hose body into an opening shape prior to injection molding of the branch portion, and it is possible to omit drilling processing after molding.

Therefore, there is no problem of leaving a burr due to the drilling work, and the inner surface of the branch can be accurately formed into a predetermined shape and size. Therefore, it is necessary to polish the inner surface of the end after the hose is formed. do not do.

Therefore, not only the polishing step can be omitted, but also the cleaning step for removing the remaining polishing powder thereafter becomes unnecessary, and the total number of steps can be reduced and the cost can be reduced.

According to the present invention, there is an advantage that the hose body (particularly the main portion) can be made of a hard resin material and the branch portions can be made of a soft resin material.

For example, in an air duct hose for an automobile, a negative pressure acts on the hose during use. Therefore, if the hose body is made of a soft material, the hose body will be deformed, whereby the suction amount of air through the hose will be increased. It reduces and causes incomplete combustion of the engine. If the entire hose is made of a hard material in order to prevent this, the sealing property at the time of connecting the mating member to the branch portion is impaired.

However, when the hose body is made of a hard resin material and the branches are made of a soft resin material according to the present invention, the hose can be given mechanical strength such as negative pressure resistance.
The branch portion can also have good sealing properties.

Further, according to the present invention, since the branch portion is injection-molded, the inner surface of the branch portion can be formed with high accuracy, which also contributes to the improvement of the sealability of the branch portion.

According to the present invention, the branch portion is formed by using the injection molding method in which the heat-fluidized material is injected with the blow-molded hose body set in the mold. The hose body and the branch portion can be sufficiently welded to each other not only when they are made of the same material but also when they are made of different materials, and the joint reliability between the two is improved.

Further, the range of material combinations of the hose body and the branch portion is expanded, and the degree of freedom in material design is also increased.

In the present invention, the main portion of the hose body is blow-molded with a thermoplastic resin, and is set in an injection molding die. The connection end is injection-molded, and the connection end is injection-molded by using a molding die having a molding cavity for the connection end and a molding cavity for the branch. The injection molding can be performed at substantially the same time.

By doing so, the same effect as described above can be obtained when molding the end of the hose body in the longitudinal direction for connecting with the mating side, that is, the inner surface of the connecting end can be molded into a predetermined shape with high accuracy. Therefore, after the molding, it is possible to omit the polishing process of the inside thereof, and it is possible to omit the subsequent cleaning step for removing the polishing powder.

Further, in the present invention, since the branch portion and the connecting end portion can be simultaneously injection-molded by using the same molding die (it is also possible to use another molding die), the number of steps for manufacturing the hose is reduced. And the advantage of simplification.

When the hose connecting end portion and the branch portion are formed of the same material, the common cavity is formed by connecting the forming cavity of the connecting end portion of the forming die with the branch portion forming cavity. Material can be injected into the cavities.

On the other hand, when the connecting end portion and the branch portion are made of different materials, the forming cavity and the branch portion forming cavity of the connecting end portion are provided with independent runners, and are formed by independent injection machines. Different cavities can be injected into the respective cavities at the same time or at a certain time difference (substantially at the same time).

[0035]

Embodiments of the present invention will now be described in detail with reference to the drawings. In FIG. 1 (E), 10 is a resin hose suitable for use as an air duct hose for automobiles, which is composed of a main part 11 and an end part 14 for connecting to a mating member at the longitudinal end thereof. It has a body 12.

A branch portion 16 for introducing blow-by gas is provided in the middle of the hose body 12 so that
It is provided so as to project in the direction perpendicular to the axis.

The main portion 11 and the connecting end portion 14 are the main portion 1
The large diameter portion 20 on one side and the small diameter portion 15 of the connecting end portion 14 are fitted to each other and fixed in the fitted state.

In this example, the main portion 11 of the hose body 12 is made of a hard resin material, and the connecting end portion 14 and the branch portion 16 are made of the same and soft resin material.

Incidentally, a polypropylene resin having a Rockwell hardness of 94 (R scale) (for example, EC-9B manufactured by Mitsubishi Petrochemical Co., Ltd.) is used as the hard resin material forming the main portion 11, and the connecting end portion 14 and the branch portion 16 are also provided. Examples of the soft resin material constituting the above include polypropylene resin having Shore A hardness of 75 + EPDM polymer alloy (for example, Santoprene 101-75 manufactured by Nippon Monsanto Co., Ltd.).

FIGS. 1 and 2 show an example of a method of manufacturing this resin hose 10. In this example, as shown in the figure, first, as shown in FIG.
The intermediate product 18 corresponding to 1 is manufactured by blow molding.

Specifically, a cylindrical parison is extruded from the extruder, then both longitudinal ends thereof are closed, and air is blown into the parison to blow the parison from the extruder, thereby closely contacting the inner surface of the blow molding die. Then, it is molded into a predetermined shape.

At this time, the large diameter portion 20 is provided at the end in the longitudinal direction.
And a hollow protrusion 2 corresponding to the above-mentioned branch part at an intermediate position.
Mold 2.

After the intermediate product 18 is obtained in this manner, the closed end of the large-diameter portion 20 and the tip of the protruding portion 22 are then formed into a surface perpendicular to their respective axes, as shown in FIG. Disconnect with. By cutting the protrusion 22, an opening 24 is formed there.
Is formed.

This cutting step can be performed after taking out the intermediate product 18 from the blow molding die, but it is performed by slidingly moving the hot cutter incorporated in the blow molding die before taking out from the blow molding die. You can also

After the blow molded product made of the thermoplastic resin is obtained in this manner, it is then set in the injection molding die 26 as shown in FIG.
The mold 26 is provided with a molding cavity 28 for the connecting end portion 14 and a molding cavity 30 for the branch portion 16,
These communicate with each other via the communication passage 32.

Then, when a soft resin material is injected from a predetermined gate and filled in the molding cavities 28 and 30, the connecting end portion 14 and the branch portion 16 are molded, and at the same time, the main portion 11 softened at that time. They are welded to the main part 1
1 is integrally joined.

Although the embodiment of the present invention has been described in detail above, this is merely an example. For example, according to the present invention, as shown in FIG. 3, the connecting end portion and the branch portion can be formed in various forms.

FIG. 6A shows an example in which the branch portion 34 is provided at the connecting end portion 36 of the hose body 12.

(B) is an example of the case where the branch portion 38 is provided in the main portion 11 of the hose body 12, but since the branch portion 38 is close to the connecting end portion 40, each cavity of the molding die is directly connected. In succession, the connecting end portion 40 and the branch portion 38 can be simultaneously injection-molded.

In (C), a plurality of engaging holes 42 are formed in the main portion 11 of the hose body 12, and when molding the connecting end portion 44 and the branch portion 46, the material is introduced into these engaging holes 42. In addition, the injection-molded connecting end portion 44 and the branch portion 46 are mechanically engaged with the main portion 11 in addition to being simply welded.
It is possible to further enhance the joint reliability between the connection end portion 44 and the branch portion 46.

(D) is an example in which such an engagement is made in a different form. The engaging recess 52 formed on the main portion 11 side of the hose body 12, the connecting end portion 48 and the branch portion. Fifty
The engaging convex portion 54 formed on the side of is engaged.

When the connecting end portion and the branch portion are made of different materials, independent sprues and runners leading to the connecting end portion molding cavity and the branch portion molding cavity are provided, respectively. It is also possible to inject different kinds of materials into the respective cavities at the same time or at a certain time difference (substantially substantially at the same time) with an injector.

The present invention can be applied to a hose having branch portions of various shapes and thicknesses other than the above examples, and can also be applied when the hose body itself is divided into two or more parts. The present invention can be implemented in a mode in which various modifications are made based on the knowledge of those skilled in the art without departing from the spirit of the invention.

[Brief description of drawings]

FIG. 1 is a process explanatory view of a method for manufacturing a resin hose which is an embodiment of the present invention.

FIG. 2 is another process explanatory view of the manufacturing method.

FIG. 3 is an explanatory diagram of another embodiment of the present invention.

FIG. 4 is an explanatory diagram of an embodiment of the prior invention of the present application.

FIG. 5 is an explanatory diagram of a problem to be solved by the present invention.

[Explanation of symbols]

10 resin hose 11 main body 12 Hose body 14, 36, 40, 44, 48 Connection end 16,34,38,46,50 Branch 26 Mold 28,30 Mold cavity

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI technical display area F16L 41/02 // B29L 23:22 4F

Claims (2)

[Claims] 1. A hose in which a branch portion extends from a hose body, at least a main portion of the hose body is formed by blow molding of a thermoplastic resin, and the blow molded product is set in a mold for injection molding. A method for manufacturing a resin hose, characterized in that the branch portion is injection-molded and is integrated with the hose body. 2. A hose body in which at least a main part of the hose body having a branch portion extending from the hose body is blow-molded with a thermoplastic resin and is set in an injection molding die. The end of the main part in the longitudinal direction for connection with the mating member is injection-molded, and the injection-molding of the connection end is performed by molding the molding cavity of the connection end and the branch part. A method for producing a resin hose, which comprises performing injection molding of the branch portion substantially at the same time by using a molding die having a cavity for use.