JP3395981B2 - Plastic tube and method of manufacturing the same - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plastic tube, and more particularly to a plastic tube having a relatively large diameter on one end side and a smaller diameter on the other end side for communicating with each other and having a large diameter. The present invention relates to a plastic tube having a curved hole side and a method for manufacturing the same.

[0002]

2. Description of the Related Art As a tube with a curved portion in which one end side of this kind has a relatively large diameter and the other end side has a smaller diameter and a communicating hole is formed, for example, a gasoline supply for an automobile In the swirling tank, which is provided in the gasoline tank of the system and introduces gasoline, and is made to directly and continuously feed gasoline to the carburetor,
There is a so-called return pipe configuration that is used to introduce gasoline into the swirl tank.

As is well known in the art, this return pipe receives gasoline that is recirculated from the engine side at a predetermined pressure, that is, return gasoline, in a large diameter opening on one end side and By increasing the flow velocity of the return gasoline by the narrowed inner diameter portion formed in the flow path and ejecting it from the small diameter opening portion on the other end side, the ejection pressure causes it to accumulate in the periphery in the gasoline tank. It is used for efficiently entraining gasoline and forcibly introducing it into the swirl tank, and the gasoline introduced into the swirl tank is pumped up and continuously fed to the carburetor.

Here, regarding the return pipe,
In the conventional case, it has the configuration shown in FIG.

That is, in the structure shown in FIG. 4, first, a metal tube material having a required inner diameter Aφ corresponding to the inner diameter on the large diameter side is used, and a corresponding portion extending from one end side of the metal tube material is set as a central axis. On the other hand, by bending the radius R to form a curved portion 53 with a required curvature,
Further, the first through hole 52 is secured including the formation range of the curved portion 53 from the large diameter opening 52a on the one end side, and the large diameter opening 52b on the other end side of the through hole 52 is predetermined. A tube main member 51 that is shaped according to the dimensions is provided.
In the figure, reference numeral 51a indicates a large-diameter opening 52 at the one end.
on the tube main member 51 corresponding to the a side,
a is provided to prevent the mating rubber hose from being inserted when it is inserted, 51b is provided to determine the insertion depth when the rubber hose is inserted, and 51c is provided to perform positioning when the rubber hose is attached to the turning tank. It is an annular bulge.

Separately, a metal material that can be brazed to the tube material is used, the metal material is cut, and the other end large-diameter opening 5 is formed at least on one end corresponding part side.
By forming a stepped fitting portion 57 that can be fitted as tightly as possible in 2b and by punching this, a first inner diameter of the required inner diameter A-ΔAφ corresponding to the narrowed inner diameter on the small diameter portion side. The second through hole 56 is formed, and a diaphragm opening portion 56a that is gradually expanded along the inner diameter Aφ of the first through hole 52 is formed on one end side corresponding to the stepped fitting portion 57 side. On the other end side, a tube sub-member 55 having a small diameter opening 56b formed therein is provided.

Then, the stepped fitting portion 57 of the tube sub-body member 55 is fitted into the large diameter opening 52b on the other end side of the tube main body member 51, and then the brazing 5 is performed.
8, both of them are integrally fixed to form the metal tube 50 in which the first and second through holes 52, 56 are communicated with each other. In this case, the large diameter opening 52 on the one end side
The return gasoline of a predetermined pressure received from the a into the first through hole 52 is narrowed down by the throttle opening 56a to increase the flow velocity, and the small diameter opening 5 on the other end side is passed through the second through hole 56.
By ejecting from 6b, the same effect as above can be obtained.

[0008]

However, in the metal tube 50 as the return pipe having the above-mentioned conventional structure, the metal tube material is curved and shaped to form the tube main member 51, and Tube by-product member 55 by cutting and perforating a metal material
The structure itself is complicated by connecting and fixing them together, and the structure itself is complicated, the manufacturing is laborious and costly, and the materials used are both metal. Due to the characteristics of each material, there is a disadvantage that the weight is increased more than necessary and rust is generated.

Therefore, as a means for eliminating such inconvenience, it is easily conceivable that the metal tube 50 is replaced by a plastic tube having an equivalent structure integrated by ordinary injection molding. It is to be.

Next, FIG. 5 schematically shows an outline of a manufacturing form of a plastic tube having an equivalent structure by applying a normal injection molding process.

When manufacturing a plastic tube with a curved portion in which one end side of this kind is opened to have a relatively large diameter and the other end side is opened to a diameter smaller than this to form a communicating hole, In order to mold the plastic by the integrated tube mode, in the usual case, a split mold for molding the outer shape and a first passage on the large diameter part side centering on the curved part are used. A mold device including a first slide core for forming a hole and a second slide core for forming a second through hole at the other end small diameter portion side is required. Each of the first and second slide cores of the
It will be constructed so that it can be inserted and removed only in one direction.

That is, in the embodiment shown in FIG. 5, the plastic tube 60 has a central axis by using a basic mold (not shown in the drawing) for the outer shape molding by an injection molding device for a plastic molding material. On the other hand, an outer shape including a curved portion 62 having a required curvature depending on the radius R, an annular bulging portion 61a for preventing the rubber hose from coming off when the rubber hose is inserted, and an annular bulging portion 61b for determining the insertion depth of the rubber hose. The shaped tube main body 61 is molded, and with respect to the tube main body 61, the first slide core 7 for forming the large diameter portion side through hole is centered on the curved portion 62.
By using 1, the inner diameter A from the large diameter opening 63a side at one end
By using the first through hole 63 by φ and the second slide core 72 for forming the small diameter side through hole, the second by the inner diameter A-ΔAφ narrowed down from the other end small diameter opening 64a side. The through holes 64 are formed by simultaneous molding so as to communicate in series.

In the plastic tube 60 constructed as above, the large diameter opening 63a is formed at one end.
The return gasoline having a predetermined pressure which is received from the side into the first through hole 63 having the inner diameter Aφ passes through the second through hole 64 having the narrowed inner diameter A-ΔAφ, while increasing the flow velocity, the other end small diameter opening By ejecting from the portion 64a side, the same effect is achieved.

The plastic tube 6 having the above structure
In the case of 0, since it can be integrally molded by each shot by the injection molding device, the metal tube 5
Unlike the case of 0, there is no need for processing or assembling the material, and mass production and cost reduction are possible, but on the other hand, the following various problems occur.

That is, (a) In plastic molding, a portion corresponding to the push-cut by the first and second slide cores 71 and 72, which inevitably causes burrs in the curved portion 62,
The burr thus generated causes turbulent flow in the return gasoline that is narrowed down to the second through hole 64 through the first through hole 63, reduces the injection pressure, and in the worst case, the through hole. There is an inconvenience such as closing the entrance of 64, and it can be said that the prevention of the burr is impossible due to the structure of the mold device. Furthermore, the burr removal after molding is also impossible. It is extremely difficult. (B) With the tip surfaces of the first and second slide cores 71 and 72 in contact with each other, the first and second passages are inserted into the plastic tube main body 61. Since it is necessary to form the holes 63 and 64 in series, as a result, the intersection of the central axes of the one end side and the other end side must be within the range of the curved portion 62, and the curved portion 62. The curvature of can not be increased beyond a certain limit. It is subject to restrictions on freedom of the above, and the like.

Therefore, the object of the present invention is to
A return pipe of this kind, which solves the above-mentioned problems of the related art and can provide a desired structure, is to provide a plastic tube and a manufacturing method thereof.

[0017]

In order to achieve the above object, the present invention provides an integral molding using a mold by applying a plastic sympress molding process, and a simple and easy finishing process after molding. It is intended to obtain a plastic tube having a desired structure.

The sympress molding process is as follows.
This is a known technique that has recently been proposed as a means for obtaining a hollow molded product by pressurizing gas pressure to the injected plastic molding material in accordance with injection molding of the plastic molding material. The method will be briefly described.

That is, in this sympress molding process, first, a required amount of plastic molding material smaller than the volume of the molding space is injected and injected into the molding die, or the inside of the molding space is completely filled. Injection fill to fill. Then, by injecting a gas of a predetermined pressure into the molding die, this injection gas pressure exerts a pressure on the portion of the injection plastic molding material in which the injection gas pressure is relatively easy to flow, and the amount of gas smaller than the molding space volume of the mold is applied. When the plastic molding material is poured into the space, the plastic molding material flows along the mold inner surface of the remaining upper portion in the mold,
Further, when a plastic molding material in an amount that completely fills the molding space of the mold is injected into the space, the unnecessary plastic molding material in this molding space is pushed out from the molding space by the injection gas pressure, and the metal molding The plastic molding material is pressed against the inner surface of the mold in a predetermined thickness.
In this way, a molded product having a required outer shape in which the inner side is hollow due to the injected gas is manufactured.

That is, the present invention is a plastic tube having a relatively large diameter on one end side and a smaller diameter on the other end side, the tube main body having a curved portion with a required curvature. While being formed, the inside of the tube main body has a first through hole with a required inner diameter including the large-diameter opening on the one end side including the curved portion range, and a small-diameter opening on the other end side from the first through-hole. It is a plastic tube characterized in that a second through hole having an inner diameter narrowed down to a smaller diameter than the first through hole is formed in series.

Further, the present invention is a method of manufacturing a plastic tube having a relatively large diameter on one end side and a smaller diameter on the other end side, which is produced by applying a sympress molding process. In the mold, after filling the molding space, or injection filling or injecting a plastic molding material having a required amount of fluidity smaller than the molding space volume, subsequently, by injecting a gas of a predetermined pressure, By pressing the plastic molding material against the inner surface of the mold by the gas pressure,
The outer shape of the tube main body having the curved portion with the required curvature is molded, and the required inner diameter is provided inside the injection gate portion of the plastic molding material, the gas injection port, and one end portion side including the curved portion range. Corresponding to the second through hole having the inner diameter narrowed to a smaller diameter than the first through hole by the slide core additionally provided on the other end side. The step of separately forming the preforming holes, and taking out the tube main body after the molding of the respective parts is taken out from the molding die, and cutting and removing the relevant parts including the injection gate part and the gas injection port, A plastic tube characterized by including at least a step of opening a large-diameter opening on the side of the section and a step of opening a second through hole communicating with the first through hole from the preforming hole. Manufacturing of It is the law.

[0022]

Therefore, according to the plastic tube of the present invention, in the inside of the tube main body portion having the curved portion due to the required curvature, the first portion having the required inner diameter including the curved portion range from the large-diameter opening on the one end side is provided. Since a through hole and a second through hole having an inner diameter narrowed down to a smaller diameter than the first through hole from the small diameter opening on the other end side are formed in series, the through hole and The fluid having a predetermined pressure to be received in the first through hole can be ejected from the small diameter opening portion while passing through the curved portion and increasing the flow velocity by the second through hole.

According to the method of the present invention, the first through hole having a relatively large diameter is formed in the plastic tube having the above-described structure, that is, in the inside including the curved portion range on the one end side of the tube main body. It is possible to easily integrally form the plastic tube having the second through hole, which has the smaller diameter than the first through hole and communicates with the inside, on the other end side.

[0024]

Embodiments of a plastic tube and a method of manufacturing the same according to the present invention will be described below in detail with reference to FIGS. 1, 2 and 3.

FIG. 1 is a sectional view showing a schematic structure of a plastic tube to which an embodiment of the present invention is applied.
Further, FIG. 2 and FIG. 3 are cross-sectional views respectively schematically showing the forms of the plastic tube before and after molding by the sympress molding process in the above embodiment.

That is, in the structure of the embodiment shown in FIG. 1, the plastic tube 10 is provided with a curved portion 12 having a required curvature by the radius R with respect to the central axis by applying a sympress molding process described later. , In this case, the outer shape is formed in a portion located at about ⅔ of the entire length from one end side, and each annular bulging portion 11a for reinforcement is provided within the ⅔ range portion. The formed tube main body 11 is molded. Then, in the tube main body 11, a large-diameter opening 13a on one end side is formed.
To a required inner diameter Aφ including the formation range of the curved portion 12
Through the first through hole 13 and the small diameter opening 14a on the other end side
From the inner diameter A- that is narrowed to a smaller diameter than the first through hole 13
The second through hole 14 formed by ΔAφ is formed in series.

Therefore, even in the plastic tube 10 constructed as described above, the large diameter opening 13a is formed at one end.
The return gasoline having a predetermined pressure, which is received from the side into the first through hole 13 having the inner diameter Aφ, is narrowed to a diameter smaller than the hole diameter of the first through hole 13 and the second through hole 14 having the inner diameter A−ΔAφ.
After that, while increasing the flow velocity, the other end small diameter opening 14a
By ejecting from the side, for example, the same action as in the case of the return pipe described above can be achieved.

Next, the procedure for manufacturing the plastic tube of this embodiment having the above-mentioned structure will be described.

As described above, the plastic tube 10 according to this embodiment is manufactured by applying the sympress molding process, and the plastic tube 10 is integrally molded by the sympress molding process. As a molding die of this, here, as shown in FIG. 2, a set of basic die members 31, 3 made into split molds.
1 and a slide core 4 assembled to these mold members
1 and are used.

That is, the set of basic mold members 31,
As shown in FIG. 2, the reference numeral 31 corresponds to the outer shape of the plastic tube 10 to be molded, has a curved molding portion 32a with a radius R, and has one end side, in this case, A hollow main body molding portion 32 having an extension portion 32b on the upper side is formed, and the extension portion 32b is formed.
The injection gate 33 and the gas inlet 34.
And a core pin 42 of a predetermined length and outer diameter projected from the slide core 41 is inserted from the side corresponding to the other end, in this case, from the lower side as well. .

However, when molding the plastic tube 10 by the sympress molding process using the above molding die, first, from the injection gate portion 33 to the inside of the main molding portion 32 including each molding portion. A required amount of heat-melted plastic molding material a smaller than the molding space volume is injected and injected. Here, the plastic molding material a thus injected is once accumulated in the lower part of the main molding part 32 and is radiated through the inner surface of the mold,
Although it is gradually cooled and solidified from the portion in contact with the inner surface, the molten state inside the plastic molding material is maintained.

Subsequently, until this state continues, this time, the gas b having a predetermined pressure is injected from the gas injection port portion 34 into the main molding portion 32. Therefore, this injected gas pressure b ₁ acts on the molten portion of the surface of the retained plastic molding material a in the molten state, which is relatively easy to flow, and the molten portion is pressed. As a result, the melted portion a ₁ flows along the inner surface of the mold as indicated by the arrow, and is pressed against the inner surface of the mold while covering the entire inner surface of the mold, and also in this case, It is gradually cooled and solidified through the inner surface, and as a result, molding is performed with the required outer shape in which the inside is hollow due to the injection gas pressure.

Next, as another embodiment, the heated and melted plastic molding material a is injected into the main molding portion 32 including each molding portion of the molding die to completely fill the molding space of this molding die. Then, the plastic molding material a is filled in the molding space. In this state, when a gas having a predetermined pressure is injected from the gas injection port 34 into the main molding part 32, a part of the plastic molding material a filled in the molding space is extruded from the molding space. With the plastic molding material a covering the inner surface of the molding die, the plastic material a is pressed against the inner surface of the die, and the inside of the molding material is hollow due to the injection gas pressure as in the above-described embodiment. Shaped plastic tubes can be obtained.

In the above embodiment, a so-called gas such as air is used by pressurizing it together with an inert gas such as nitrogen gas under predetermined conditions. Depending on the conditions, it is preferable to use a gas having properties suitable for molding this kind of plastic tube.

That is, in this way, in the sympress molding process in this manner, as a result, the injection gate portion 33 and the gas injection port portion 34 are provided at the one end side as shown in FIG. A preforming hole 14 which has a forming portion 11b corresponding to the extended portion 32b having a groove and is formed by the core pin 42 of the slide core 41 on the other end side.
The plastic tube material 10a composed of the tube main body 11 having b can be integrally molded at the same time.

The molded plastic tube material 10a is made up of a set of basic mold members 31, 3
After taking it out from inside 1, the molding part 11b is cut along the cutting line B
By cutting and removing from the -B portion, the large diameter opening 13a on one end side is opened to finish the first through hole 13,
In addition, the preforming hole 14b is bored by an appropriate means to open and finish the second through hole 14 communicating with the first through hole 13, and thus, as shown in FIG. It is possible to manufacture the plastic tube 10 having the intended structure shown in FIG.

[0037]

As described above in detail with reference to the embodiments,
According to the present invention, by applying the sympress molding process, the outer shape of the tube main body portion having the curved portion is molded, and at the same time, the first inner diameter of the required inner diameter is formed inside the one end portion side including the curved portion range. After forming a space portion corresponding to the through hole on the other end side, a preforming hole corresponding to the second through hole having an inner diameter narrowed down to a smaller diameter than the first through hole is separately formed, and then one end portion is formed. Since the large diameter opening on the side is opened and the preforming hole on the other end side is bored to open the second through hole communicating with the first through hole, Has a first through hole having a relatively large diameter in the inside including the curved portion range on one end side of the portion, and has a smaller diameter than the first through hole inside the other end side. It is easy to integrally mold a plastic tube that has a second through hole that communicates with each other. There is a long.

[Brief description of drawings]

FIG. 1 is a sectional view showing a schematic configuration of a plastic tube to which an embodiment of the present invention is applied.

FIG. 2 is a cross-sectional view schematically showing a form of a plastic tube before being molded by a sympress molding process in the same example.

FIG. 3 is a cross-sectional view schematically showing the form after molding.

FIG. 4 is a cross-sectional view showing a schematic configuration of a metal tube according to a conventional example.

FIG. 5 is a cross-sectional view schematically showing an outline of a manufacturing method of a plastic tube by a normal injection molding process in a conventional example.

[Explanation of symbols]

10 plastic tubes 10a plastic tube material 11 Tube main body 11a annular bulge 11b Molded part for extension 12 curved section 13 First through hole 13a large diameter opening 14 Second through hole 14a Small diameter opening 14b Preforming hole 31 1 set of basic mold members 32 Main molding part 32a Curved forming part 32b extension 33 Injection gate 34 Gas inlet part 41 slide core 42 core pins

─────────────────────────────────────────────────── --- Continuation of the front page (56) Reference JP-A-4-189528 (JP, A) JP-A-4-103317 (JP, A) JP-A-5-77337 (JP, A) JP-A-61- 202827 (JP, A) JP-A-52-19815 (JP, A) Actual public 62-5308 (JP, Y1) Actual public 58-43660 (JP, Y1) (58) Fields investigated (Int.Cl. ⁷ , DB name) F02M 37/00 F16L 11/04-11/12 B23D 23/00 B29C 45/00 B29C 45/26-45/44 B29C 49/02-49/24 B29C 49/48-49/54

Claims (2)

(57) [Claims] 1. A plastic tube having a relatively large diameter on one end side and a smaller diameter on the other end side, the tube main body having a curved portion with a required curvature, and Inside the tube main body, a first through hole having a required inner diameter from the large diameter opening on the one end side including the curved portion range and a first through hole from the small diameter opening on the other end side. Yes formed in series and a second through hole by an inner diameter which is narrowed down to a smaller diameter than the first through hole, with respect to the molding die, plastic
After injecting the molding material into the mold,
Inject a gas with a predetermined pressure,
Tick molding material is pressed against the inner surface of the mold
And the second through hole is formed by an attached slide core.
Narrowed to a diameter smaller than the first through hole formed by
From the preformed hole having the inner diameter
A plastic tube characterized by being formed by piercing so as to communicate with a hole . 2. A method of manufacturing a plastic tube having a relatively large diameter on one end side and a smaller diameter on the other end side, wherein a plastic molding material is injected into a molding die. after subsequently by injecting a predetermined pressure of gas, together with the plastic molding material by the gas pressure against the inner surface of the mold, thereby forming the outer shape of the tube main body portion having a curved portion due to the required curvature, the injection gate portion of the plastic molding material, the gas inlet portion, and the inside of the end portion corresponding side including the curved portion ranges, a space corresponding to the first through hole of the required internal diameter, the other end Is a step of separately forming a preforming hole corresponding to the second through hole having an inner diameter narrowed to a diameter smaller than that of the first through hole by the attached slide core, and the forming of each part is completed. Ju A step of taking out the main body portion from the molding die, cutting and removing the relevant portion including the injection gate portion and the gas injection port portion, and opening a large-diameter opening portion on one end side; and the preforming hole And a step of opening a second through hole communicating with the first through hole from the above. At least, a method of manufacturing a plastic tube, comprising: