JP2019181889A - Synthetic resin pipe with branch pipe - Google Patents

Abstract

To provide a synthetic resin pipe with a branch pipe in which a molding defect hardly generates during injection molding at a portion from which the branch pipe branches off.SOLUTION: A synthetic resin pipe 1 with a branch pipe is formed by injection molding of a synthetic resin. The synthetic resin pipe 1 with the branch pipe has a main pipe 11 formed into a hollow pipe shape, and the branch pipe 12 formed into a hollow pipe shape so as to branch off from a pipe wall of the main pipe 11. A pipeline of the main pipe 11 and a pipeline of the branch pipe 12 are blocked from each other by a pipe wall W of the main pipe at a portion from which the branch pipe 12 branches off from the main pipe 11. A protruding part 13 protruded in a conical shape or columnar shape or ridge shape toward an inner space of the pipeline of the branch pipe 12 is formed at a portion where a pipe wall of the main pipe 11 faces to an inner space of the pipeline of the branch pipe 12.SELECTED DRAWING: Figure 1

Description

The present invention relates to a synthetic resin pipe. In particular, the present invention relates to a synthetic resin pipe with a branch pipe having a main pipe formed in a hollow tubular shape and a hollow tubular branch pipe.

Synthetic resin pipes are used as pipe joints for connecting rubber tubes and flexible hoses in physics and chemistry equipment, or for hydraulic pipes and pipe joints used in automatic transmissions of automobiles. It is used for various purposes as a component. The synthetic resin pipe can be manufactured by injection molding. In that case, a highly accurate synthetic resin pipe can be manufactured with high manufacturing efficiency.

Further, a synthetic resin pipe with a branch pipe having a main pipe formed in a hollow tubular shape and a hollow tubular branch pipe is also known. For example, Patent Document 1 discloses an injection mold for manufacturing a T-shaped branch pipe (pipe joint). According to the mold, the inner peripheral surface shape of the branch portion is smooth. A letter-shaped branch pipe can be manufactured by injection molding of synthetic resin.

Japanese Patent Laid-Open No. 10-235684

In the T-shaped branch pipe of Patent Document 1, the main pipe line and the branch pipe (a pipe branched from the main pipe) communicate with each other. Such a branch pipe is used for the purpose of joining or dividing the fluid flows of the main pipe and the branch pipe.
Depending on the use of the synthetic resin pipe, the main pipe line and the branch pipe line may not communicate with each other. For example, when the branch pipe part is used exclusively for supporting the main pipe, or when the branch pipe part is used exclusively for fixing or sealing the end of another tube, the main pipe and the branch pipe are used. Synthetic resin pipes with branch pipes that do not communicate with each other are used.

When a synthetic resin pipe with a branch pipe that does not communicate with the main pipe and the branch pipe is manufactured by injection molding, the following problems with molding defects are likely to occur at the part where the branch pipe branches from the main pipe. The inventor discovered.
That is, as shown in FIG. 7, the branch pipe 92 is formed to branch from the pipe wall of the main pipe 91, and the pipe line of the main pipe 91 and the pipe pipe of the branch pipe 92 are blocked by the pipe wall of the main pipe. It has been found that when the synthetic resin pipe 9 with a branch pipe is integrally formed by injection molding, molding failure tends to occur at the branch portion of the branch pipe.

An object of the present invention is to provide a synthetic resin pipe with a branch pipe in which a branch pipe is branched and a molding failure hardly occurs during injection molding.

When the inventor investigated the cause of molding failure, it was found that the molding failure occurred because the core pin forming the branch pipe passage was deformed by losing the resin pressure.
When the synthetic resin pipe 9 with a branch pipe in which the pipe path of the main pipe 91 and the pipe path of the branch pipe 92 are blocked by the pipe wall of the main pipe as shown in FIG. 7 is integrally formed by injection molding. In general, injection molding is performed by a mold configuration as shown in FIG. Cavity molds D1 and D2 that define the outer peripheral shape of the main pipe 91 and branch pipe 92, main pipe core mold D3 that defines the inner surface shape of the main pipe 91, and branch pipe core mold D9 that defines the inner surface shape of the branch pipe 92, A cavity filled with a resin is formed, and the resin is injected into the cavity to solidify the resin, whereby the synthetic resin pipe 9 with a branch pipe is manufactured. Here, since the mold is configured so that the pipe line of the main pipe 91 and the pipe line of the branch pipe 92 are blocked by the pipe wall of the main pipe, the branch pipe core type D9 is on the side of the branch portion with the main pipe 91. It cannot be supported and is supported in a cantilevered manner.

When the branch pipe core type D9 that defines the inner surface shape of the branch pipe 92 is cantilevered, as shown in FIG. 8, when the injected resin flows from the branch portion of the main pipe and the branch pipe toward the branch pipe. Because of the non-uniformity of the resin flow, the branch pipe core mold D9 tends to bend, resulting in a problem of poor molding in which the thickness of the formed branch pipe 92 becomes non-uniform. When the deflection of the branch pipe core type D9 is excessive, the branch pipe core mold D9 is molded with a hole in the pipe wall, or the branch pipe core mold D9 cannot be removed from the molded branch pipe 92. It becomes a problem. As the branch pipe becomes thinner and longer, such a problem becomes more obvious.

As a result of intensive studies, the inventor has provided a hollow having a specific shape at the tip of the branch pipe core type, and the pipe wall of the main pipe in the synthetic resin pipe with a branch pipe faces the internal space of the branch pipe. It has been found that the above-mentioned problem can be solved by forming a protrusion having a specific shape in the portion, and the present invention has been completed.

The present invention relates to a synthetic resin pipe with a branch pipe formed by injection molding of a synthetic resin, a main pipe formed into a hollow tubular shape, and a branch pipe formed into a hollow tubular shape so as to branch from a pipe wall of the main pipe Where the branch pipe branches from the main pipe, the main pipe line and the branch pipe line are blocked by the main pipe wall, and the main pipe wall is the internal space of the branch pipe. The portion facing the pipe is a synthetic resin pipe with a branch pipe in which a projecting portion protruding in a cone shape, a columnar shape, or a convex shape is formed toward the internal space of the branch pipe passage ( First invention).

In the first invention, preferably, an annular surface is formed so as to surround the protruding portion, and the annular surface is substantially continuous with the outer peripheral surface of the pipe wall of the main pipe located outside the branch pipe. (Second invention). In the first invention, preferably, the protruding amount of the protruding portion is 0.3 to 1.2 times the inner diameter of the branch pipe (third invention).

When the synthetic resin pipe with branch pipe of the present invention (the first invention) is molded by injection molding, the branch pipe core mold is not easily deformed, and molding defects are unlikely to occur.
Furthermore, when it is made like 2nd invention or when it is made like 3rd invention, a deformation | transformation of a branch pipe core type | mold is suppressed more and generation | occurrence | production of a molding defect is suppressed more.

It is sectional drawing which shows the shape of the synthetic resin pipes with a branch pipe of 1st Embodiment. It is sectional drawing which shows the detailed shape of the branch part of the synthetic resin pipes with a branch pipe of 1st Embodiment. It is sectional drawing which shows typically the injection molding process at the time of manufacturing the synthetic resin pipe with a branch pipe of 1st Embodiment. It is sectional drawing which shows the shape of the synthetic resin pipes with a branch pipe of 2nd Embodiment. It is sectional drawing which shows the example of the other shape of a protrusion part. It is sectional drawing which shows the drilling process which adds a hole to the synthetic resin pipe with a branch pipe of 1st Embodiment. It is sectional drawing which shows the shape of the conventional synthetic resin pipes with a branch pipe. It is sectional drawing which shows typically the injection molding process at the time of manufacturing the conventional synthetic resin pipe with a branch pipe.

Hereinafter, embodiments of the invention will be described with reference to the drawings. The invention is not limited to the individual embodiments shown below, and can be carried out by changing the form.
FIG. 1 is a cross-sectional view showing the shape of a synthetic resin pipe with branch pipes according to the first embodiment. The detailed shape of the branch part is shown in FIG.

As will be described later, the branch resin-made synthetic resin pipe 1 is a pipe integrally formed by synthetic resin injection molding. The synthetic resin pipe 1 with a branch pipe has a main pipe 11 formed in a hollow tubular shape. The synthetic resin pipe 1 with a branch pipe has a branch pipe 12 formed in a hollow tubular shape so as to branch from the pipe wall of the main pipe 11. Specific shapes of the main pipe 11 and the branch pipe 12 are not particularly limited as long as they can be formed by injection molding. In the present embodiment, the main pipe 11 and the branch pipe 12 are straight pipes. Further, the angle at which the main pipe and the branch pipe branch is not particularly limited, but in this embodiment, the branch pipe 12 branches from the main pipe 11 in a direction orthogonal to the main pipe 11.

At the point where the branch pipe 12 branches from the main pipe 11, the pipe line of the main pipe 11 and the pipe line of the branch pipe 12 are blocked by the pipe wall W of the main pipe 11. The main pipe 11 and the branch pipe 12 do not communicate with each other. That is, the main pipe 11 is a straight tubular body whose both ends are open, while the branch pipe is a blind pipe whose one end is open and the other end (main pipe side) is closed. The pipe wall W of the main pipe 11 is a connection part (branch part) with the branch pipe 12 and is continuously provided so that there is no hole across the outer side and the inner side of the branch pipe.

Such a branch pipe-attached synthetic resin pipe 1 can be used, for example, for connecting rubber tubes of physics and chemistry equipment. The rubber tubes are connected to each other by the main pipe 11 by extrapolating the rubber tubes to both ends of the main pipe 11 of the synthetic resin pipe 1 with a branch pipe. Moreover, the synthetic resin pipe | tube 1 with a branch pipe and rubber tube piping can be fixed by inserting the part of the branch pipe 12 in a grommet etc.

Although not essential, the main pipe 11 and the branch pipe 12 may be integrally formed with a seal groove, a bulge portion, an attachment structure, and the like as necessary. In the present embodiment, bulge portions are formed at both end portions of the main pipe 11 to improve the connection with the rubber tube and the sealing performance. Moreover, you may form a thread part, a groove | channel, etc. in the exterior or inside of a branch pipe.

As shown in FIG. 2, a protruding portion 13 is formed in a portion where the pipe wall W of the main pipe 11 faces the internal space of the branch pipe 12. The protruding portion 13 protrudes in the shape of a cone or a column toward the internal space of the branch pipe 12.

Although not essential, an annular surface P1 is formed so as to surround the protrusion 13, and this annular surface P1 is substantially the same as the outer peripheral surface P2 of the pipe wall of the main pipe located outside the branch pipe 12. It is preferable that they are provided continuously. Here, the fact that the annular surface P1 and the outer peripheral surface P2 of the tube wall of the main pipe are substantially continuous means that the annular surface P1 with respect to the outer peripheral surface P2 of the main pipe located at a predetermined radius from the center line of the main pipe 11. Also means that they are located at substantially the same radius from the center line of the main pipe 11. If the branch pipe 12 is not provided, it is preferable that the annular face P1 and the outer peripheral face P2 of the pipe wall of the main pipe have a positional relationship in which they are smoothly continued.

Further, although not essential, the protrusion 13 has a protrusion amount H of 0.3 to 1.2 times the inner diameter d of the branch pipe 12, that is, 0.3 ≦ H / d ≦ 1. It is preferably set to be 2. Moreover, it is preferable that the protrusion amount H of a protrusion part is 0.1 mm-2 mm.

Further, although not essential, the protrusion 13 provided to protrude in the shape of a cone or a column has a diameter a of 0.5 to 0.95 times the inner diameter d of the branch pipe, that is, 0.5 ≦ It is preferable to set so that a / d ≦ 0.95. Moreover, it is preferable that the diameter a of a protrusion part is 0.3 mm-2.5 mm.

When the protrusion 13 is provided in a cone shape, the angle b formed by the cone surface of the cone and the outer peripheral surface of the main pipe 11 is preferably 40 degrees or more and less than 90 degrees. Moreover, when the protrusion part 13 is provided in cone shape, although a protrusion part may be a pyramid shape, it is especially preferable that it is a cone shape. Further, the apex angle portion of the cone may be sharp, but R may be provided so that the radius R is about a / 20 to a / 5. Further, the apex angle portion of the cone may be cut off, and the protruding portion may be formed so as to have a trapezoidal cone shape (conical truncated cone or truncated pyramid) in which the tip of the cone is flattened.

When the protruding portion 13 is provided in a columnar shape, the protruding portion may be a prismatic shape or a cylindrical shape.

FIG. 5 illustrates a cross section of a modified example of the shape of the protruding portion.
In the example of FIG. 5A, the protruding portion 14 is formed in a truncated pyramid shape with the tip of the quadrangular pyramid cut off and the tip made flat.
In the example of FIG. 5B, the protrusion 15 is formed in a conical shape having a rounded tip with a rounded end.

When the annular surface P1 is formed so as to surround the protruding portion 13, the width t of the tubular surface P1 is 0.03 to 0.2 times the inner diameter d of the branch pipe 12, that is, 0 It is preferable to set such that .03 ≦ t / d ≦ 0.2.

Although the resin material which comprises the synthetic resin pipe | tube 1 with a branch pipe will not be specifically limited if it is a synthetic resin material which can be injection-molded, It is preferable that it is a thermoplastic resin. Examples of the thermoplastic resin that can be injection-molded include polyolefin resins, polyamide resins, and engineering plastics. The synthetic resin pipe 1 with a branch pipe of the said embodiment is formed with the polypropylene resin.

With reference to FIG. 3, an injection molding process for manufacturing the synthetic resin pipe 1 with a branch pipe according to the embodiment will be described. The injection mold includes cavity molds D1 and D2 having shapes that match the outer peripheral surface shapes of the main pipe 11 and the branch pipe 12. In the mold shown in FIG. 3, cavity molds D1 and D2 are provided in the vertical direction in the figure so as to be opened and closed. The injection mold has a main pipe core mold D3 having a shape matching the inner peripheral surface shape of the main pipe 11, and a branch pipe core mold D4 having a shape matching the inner peripheral surface shape of the branch pipe 12. . The main pipe core mold D3 and the branch pipe core mold D4 are cavity molds D1, D1 and D2 with a sliding mechanism and a detachable mechanism as appropriate so that the mold can be opened and removed after the synthetic resin pipe with branch pipe 1 is formed. It may be assembled to D2. In FIG. 3, only the main parts of the cavity mold and the core mold are shown, and other parts and details are omitted.

During the injection molding process, the mold is closed as shown in FIG. At this time, the tip of the branch pipe core mold D4 is separated from the outer peripheral surface of the main pipe core mold D3. In addition, a recessed portion D4a having a shape corresponding to the protruding portion 13 of the synthetic resin pipe 1 with a branch pipe is provided at the distal end portion of the branch pipe core mold D4.

After the mold is closed and the cavity C is formed, resin is injected into the cavity through the gate G. In this embodiment, the resin is injected from the one end side (right side in the figure) of the main pipe 11 toward the other end or the branch pipe. FIG. 3 shows a state in which the injected resin is filling the cavity C, and shows a state in which the injected resin enters the branch pipe portion.

In a state where the injection of the resin is completed and the cavity C is sufficiently filled with the resin, the resin is solidified while maintaining the pressure of the resin. The solidifying means is made according to the type of resin. If the resin is a thermoplastic resin, the resin is solidified by cooling. When the resin is sufficiently solidified, the mold is opened and the molded synthetic resin pipe 1 with a branch pipe is taken out of the mold. Through the above process, the synthetic resin pipe 1 with a branch pipe of the above embodiment is manufactured by injection molding.

The operation and effect of the above-mentioned branch pipe-attached synthetic resin pipe 1 will be described. In the synthetic resin pipe 1 with a branch pipe, the pipe line of the main pipe 11 and the pipe line of the branch pipe 12 are blocked by the pipe wall W of the main pipe 11 at a location where the branch pipe 12 branches from the main pipe 11. In a portion where the tube wall W faces the internal space of the branch pipe 12, a projecting portion 13 that protrudes in a cone shape or a column shape toward the internal space of the branch pipe 12 is formed. . With this configuration, when the synthetic resin pipe 1 with a branch pipe is injection-molded, the branch pipe core mold D4 is less likely to be deformed and molding defects are less likely to occur.

The protruding portion 13 in the branch pipe-made synthetic resin pipe 1 is formed corresponding to the recessed portion D4a provided at the end of the branch pipe core mold D4. In the injection molding process of the synthetic resin pipe 1 with a branch pipe of the above embodiment, when the resin is injected, the branch pipe core mold D4 is cantilevered as in the case of the prior art shown in FIG. Although it is the same, branch pipe core type D4 becomes difficult to bend by providing concave part D4a in the end of branch pipe core type D4. The mechanism of action estimated by the inventor will be described below.

When the resin is filled in the cavity C of the mold, the resin flowing in from the gate G side of the main pipe is a part where the branch pipe branches, and before the branch pipe enters the branch pipe, The space between the tip of the mold D4 and the main pipe core mold D3 is filled. While this portion is not filled, the resin pressure is difficult to increase, and the resin is less likely to enter the portion that becomes the branch pipe. Accordingly, the resin enters the recessed portion D4a at the distal end of the branch pipe core type D4 prior to the portion that becomes the branch pipe, and the resin in contact with the distal end part of the branch pipe core type D4 is cured at a slightly earlier timing. It will follow.

Thereafter, the resin enters the portion that becomes the branch pipe. This state is shown in FIG. Since the penetration of the resin into the portion that becomes the branch pipe is difficult to be uniform in the circumferential direction, there is a possibility that a force to bend and deform the branch pipe core type D4 acts. However, if the recessed portion D4a is provided at the distal end portion of the branch pipe core mold D4, the resin entering the recessed portion D4a and solidifying prevents the distal end portion of the branch tube core mold D4 from moving. This prevents the branch pipe core type D4 from being bent or deformed.

In the prior art as shown in FIG. 7 and FIG. 8, since the recessed portion is not provided at the distal end of the branch pipe core type D9 and the distal end has a flat shape, the resin is solidified at the distal end portion. However, the resin being solidified and the tip of the branch pipe core type D9 are easily slipped and displaced, and the branch pipe core type D9 is easily bent and deformed as shown in FIG.

As described above, when the protrusion 13 is provided at the branch portion of the branch pipe 12 as in the case of the synthetic resin pipe 1 with a branch pipe, the branch pipe core type D4 becomes difficult to bend at the time of injection molding. The deviation from the position is suppressed, and molding defects are less likely to occur.

An annular surface P1 is formed so as to surround the protruding portion 13 from the viewpoint of more effectively suppressing flexural deformation and molding failure of the branch pipe core mold D4. It is preferable that the outer peripheral surface P2 of the pipe wall W of the main pipe 11 located outside is substantially continuous. In this way, the tip of the branch pipe core mold D4 is directly pushed by the flow of the resin filling the portion that becomes the pipe wall of the main pipe while flowing in the extending direction of the main pipe, and the branch pipe core mold D4 Is less likely to bend. Further, since the solidification of the resin that has entered the space between the distal end portion of the branch pipe core mold D4 and the main pipe core mold D3 is unlikely to be delayed, the branch pipe made of the resin that enters and solidifies into the recessed portion D4a. The support action of the core tip is effectively exhibited.

Further, from the same viewpoint, it is preferable that the protrusion amount H of the protrusion 13 is 0.3 to 1.2 times the inner diameter d of the branch pipe 12. The supporting action of the branch pipe core type tip part by the resin that enters and solidifies into the space between the recessed part D4a at the tip part of the pipe core type D4 and the main pipe core type D3 is particularly effectively exhibited.

The invention is not limited to the embodiment described above, and can be implemented with various modifications. Although other embodiments of the invention will be described below, in the following description, portions different from the above-described embodiment will be mainly described, and detailed descriptions of the same portions will be omitted. Moreover, these embodiments can be implemented by combining some of them or replacing some of them.

In FIG. 4, the cross section of the synthetic resin pipe | tube 2 with a branch pipe of 2nd Embodiment is shown. In this embodiment, the main pipe 21 is a bent pipe formed by bending in a circular arc shape with a predetermined bending radius, and the branch pipe 22 is provided so as to branch to the outside of the bending of the main pipe 21. In addition, a protruding portion 23 that protrudes in a protruding shape toward the internal space of the branch pipe 22 is formed in a portion where the pipe wall of the main pipe 21 faces the internal space of the branch pipe 22. ing. Other points are the same as those of the synthetic resin pipe 1 with a branch pipe of the first embodiment.

As in this embodiment, the main tube 22 may be an arcuate bent tube. Also in the synthetic resin pipe 2 with a branch pipe of this embodiment, by providing the projecting portion 23, the branch pipe core mold is prevented from being bent and deformed, and molding defects are less likely to occur.

Moreover, in the synthetic resin pipe 2 with a branch pipe of 2nd Embodiment, the protrusion part 23 is provided in the protruding item | line shape. Even if the projecting portion has a ridge shape, similarly, the movement of the branch pipe core mold tip can be prevented and the occurrence of molding defects can be suppressed. It is preferable that the protruding protrusion 23 is provided so as to extend in a direction orthogonal to the extending direction of the main pipe 22 as in the present embodiment. The protruding protrusions may be provided so as to extend in a direction intersecting or extending in the direction in which the main pipe 22 extends.
Further, a plurality of protruding protrusions may be provided, and the protrusions may be provided so as to cross each other or be parallel to each other.

Further, in the synthetic resin pipes 1 and 2 with branch pipes of the first embodiment and the second embodiment, the branch pipes 12 and 22 are straight pipes, but if the branch pipe core type can be removed, It does not have to be a straight tube. For example, the branch pipe may be bent in a circular arc shape, and the branch pipe core type may be injection molded or demolded with an arc-shaped bar shape. In addition, the angle at which the branch pipe and the main pipe intersect may be a right angle, but may also intersect at an angle.

Moreover, the specific structure of the injection mold at the time of shape | molding the synthetic resin pipe | tube with a branch pipe of the said embodiment by injection molding can be changed suitably. For example, the parting surface of the cavity type may be changed, and the structure can be slid and divided as appropriate so that the main pipe core type and the branch pipe core type can be removed according to the change of the parting surface. And it is sufficient.

In the description of the above embodiment, the embodiment in which the injection mold has the main pipe core mold D3 and the inner peripheral surface of the main pipe is formed by the main pipe core mold D3 has been described. The main pipe core mold D3 is not indispensable when molding is molded by injection molding. For example, a branch pipe is formed while forming the main pipe without a core mold by using a molding method in which resin is removed from the inside of the main pipe by fluid pressure, such as a technique called a floating core method (RFM molding method, etc.). In the case of molding using a branch pipe core mold, similarly, molding defects can be suppressed by injection molding with a recessed portion provided at the tip of the branch pipe core mold.

The use and field of use of the synthetic resin pipe with a branch pipe of the above embodiment are not particularly limited. As described above, injection molded synthetic resin pipes with branch pipes may be used as pipe joints as they are. In this case, the portion of the branch pipe can be used as a fixing member or the like.
Alternatively, the synthetic resin pipe with a branch pipe of the above embodiment may be used after being additionally processed. For example, as shown in FIG. 6, a branch is used to connect the branch pipe 12 and the branch pipe 12 to the branch pipe 12 with the branch pipe. You may make a hole in the part of the pipe wall which has interrupted the pipe and the main pipe. In the figure, the progress of the drill is indicated by a two-dot chain line. In the case of additional machining in this way, it can be used as a pipe joint that forms a branched pipe line by connecting a total of three rubber tubes to both ends of the main pipe 11 and the end of the branch pipe.

The above-mentioned synthetic resin pipe with a branch pipe can be used for, for example, a pipe joint and the like.

1 Synthetic resin pipe with branch pipe 11 Main pipe 12 Branch pipe 13 Projection part D1, D2 Cavity type D3 Main pipe core type D4 Branch pipe core type

Claims (3)

A synthetic resin pipe with a branch pipe formed by injection molding of synthetic resin,
A main pipe formed in a hollow tubular shape, and a branch pipe formed in the hollow tubular shape so as to be branched from the tube wall of the main pipe,
At the point where the branch pipe branches from the main pipe, the main pipe line and the branch pipe line are blocked by the main pipe wall,
In the portion where the pipe wall of the main pipe faces the internal space of the branch pipe line, a protrusion is formed that protrudes in the shape of a cone, column, or ridge toward the internal space of the branch pipe line. ing,
Synthetic resin pipe with branch pipe. An annular surface is formed so as to surround the protrusion,
The synthetic resin pipe with a branch pipe according to claim 1, wherein the annular surface is substantially continuous with the outer peripheral surface of the pipe wall of the main pipe located outside the branch pipe. The synthetic resin pipe with a branch pipe according to claim 1, wherein a protruding amount of the protruding portion is 0.3 to 1.2 times the inner diameter of the branch pipe.

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