JP2017222039A - Manufacturing method of synthetic resin-made pipe - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of a synthetic resin-made pipe capable of effectively removing burrs even when the burrs are produced in a part on which divided core molds abut.SOLUTION: A synthetic resin-made pipe 1 is manufactured by using injection molding. In an injection molding mold, a core mold which defines an inner surface shape of the synthetic resin-made pipe 1 is constituted by being divided into a first core mold CR1 and a second core mold CR2 arranged along holes of the pipe and abutting on each other, at least the first core mold CR1 has a columnar shape, a face AS where the first core mold CR1 abuts on the second core mold CR2 when a mold is closed is inclined with respect to a center axis m of the first core mold CR1. An injection process for injecting a synthetic resin into a mold and filling the mold with the resin is carried out, and following the injection process, a process for rotating the first core mold CR1 around the center axis m is carried out, and then burrs are removed. Thereafter, the molded synthetic resin-made pipe 1 is taken out from the mold.SELECTED DRAWING: Figure 3

Description

The present invention relates to a method for producing a synthetic resin pipe. In particular, the present invention relates to a method for manufacturing a synthetic resin pipe using injection molding.

Synthetic resin pipes are used for various purposes. Synthetic resin pipes are also used for connector members for hoses and tubes. If a synthetic resin pipe is manufactured using injection molding, the manufacturing efficiency is high and economical. In particular, it is preferable to form by injection molding up to the hole shape of the pipe because a process such as cutting is unnecessary.

A synthetic resin pipe manufacturing method in which a hole shape is formed by a core mold using an injection mold having a core mold is known. When the hole has a bent shape, or when the hole has an elongated shape, injection molding is performed by dividing the core mold to form a mold so that the core mold can be easily removed.

For example, Patent Document 1 discloses a technique for injection molding of a bent pipe. After inserting a core pin together with an inner cylinder and injecting resin, the core pin and the inner cylinder are taken out from the molded body. A technique for manufacturing a bent pipe is disclosed, and according to the manufacturing method, it is disclosed that an inner corner portion can be formed in an arc shape.

JP 2011-047487 A

However, if the core mold that forms the hole is divided, burrs may occur at the portions where the divided core molds abut each other. When burr occurs, it is not preferable because the burr is formed in a state in which the pipe is closed or a portion in which the diameter of the hole of the pipe is narrowed. Therefore, it is necessary to inspect burrs and remove burrs in a later process, which is not economical.

Moreover, although the technique disclosed in Patent Document 1 does not cause burrs at the core pin tip, insertion and removal of the inner cylinder is complicated.

An object of the present invention is to produce a synthetic resin pipe that can efficiently remove burrs even if burring occurs at a portion where the divided core mold contacts by performing injection molding by dividing a core mold that forms a hole. Is to provide.

As a result of intensive studies, the inventor has inclined the surfaces on which the core molds contact each other with respect to the central axis of the core mold, and after the pipe is injection molded, the core mold is rotated around the central axis. As a result of finding out that burrs generated at the portion where the mold contacts can be removed, the present invention has been completed.

The present invention is a method for manufacturing a synthetic resin pipe using injection molding, and includes a step of preparing an injection mold, and the injection mold includes a cavity that defines an outer surface shape of the synthetic resin pipe. And a core mold that defines the inner shape of the synthetic resin pipe, and the core mold is divided into a first core mold and a second core mold that are provided along the hole of the pipe and are in contact with each other. And at least the first core mold is cylindrical, and the surface where the first core mold and the second core mold abut when the mold is closed is inclined with respect to the central axis of the first core mold, Following the mold preparation process, the injection mold is closed, and an injection process is performed in which a synthetic resin is injected and filled into the mold cavity. Following the injection process, the first core mold is rotated about the central axis. After the core mold rotation process, the mold A method for producing a synthetic resin pipe a step of taking out the synthetic resin pipe is et molded (first invention).

In the first invention, it is preferable to extract a predetermined amount of the second core mold prior to the rotation of the first core mold (second invention). Furthermore, in the second invention, it is preferable that the synthetic resin pipe has a bent pipe shape (third invention). In the second invention or the third invention, the outer shape of the surface on the second core mold side is greater than the outer shape of the surface on the first core mold side in the portion where the first core mold and the second core mold are in contact with each other. It is also preferable that the outer shape of the surface on the first core mold side is inside the outer shape of the surface on the second core mold side when the contact is made (fourth invention). Further, in the first invention, the synthetic resin pipe has a straight pipe shape, and the second core type also has a cylindrical shape. In the core type rotating step, the second core type can be rotated together with the first core type. Preferred (5th invention).

According to the synthetic resin pipe manufacturing method of the present invention (the first invention, the second invention, and the third invention), even if burrs are generated at the portion where the divided core mold contacts, the burrs can be efficiently removed. .

Furthermore, if it carries out like 4th invention, a 1st core type | mold can be rotated largely and the removal of a burr | flash becomes more reliable. Further, according to the fifth aspect of the invention, the burrs are sandwiched between the core molds, and the burrs are more reliably removed without falling by the rotation of the core mold.

It is sectional drawing which shows the shape of the synthetic resin pipes of 1st Embodiment. It is a schematic diagram which shows the injection mold for shape | molding the synthetic resin pipes of 1st Embodiment. It is a schematic diagram which shows the process of a series of injection molding which shape | molds the synthetic resin pipes of 1st Embodiment. It is a perspective view which shows the shape of the synthetic resin pipes of 2nd Embodiment. It is a schematic diagram which shows the process of a series of injection molding which shape | molds the synthetic resin pipes of 2nd Embodiment. It is a perspective view which shows the example of the form which a core type | mold contacts. It is sectional drawing which shows the other example of a synthetic resin pipe.

Embodiments of the invention will be described below with reference to the drawings, taking as an example a synthetic resin pipe used as a connector member of a rubber tube or a synthetic resin tube. Note that the present invention is not limited to the individual embodiments described below, and the embodiments can be changed and implemented.

FIG. 1 is a sectional view of a synthetic resin pipe 1 manufactured by the synthetic resin pipe manufacturing method of the present invention. In this embodiment, the synthetic resin pipe 1 can be used as a connector member such as a rubber tube. The synthetic resin pipe 1 is a hollow pipe having a through hole reaching from one end to the other end. The synthetic resin pipe 1 of the present embodiment has a bent tube shape. That is, the synthetic resin pipe 1 is formed as a bent pipe in which the straight tubular first tubular portion 11 and the second tubular portion 12 are connected at an angle of about 90 degrees, and an L-shape is formed in the inside thereof. A continuous through hole is provided. In the synthetic resin pipe 1 of the present embodiment, the first tubular portion 11 and the second tubular portion 12 each have a cylindrical outer peripheral surface and a cylindrical inner peripheral surface.

The synthetic resin pipe 1 can be used as a connector member for piping by covering the both ends with rubber tubes. It is also possible to use the end portion inserted into the connection hole of the connection partner member. The synthetic resin pipe 1 may be provided with an annular protrusion 13 that prevents the tube from coming off at the end. Further, the synthetic resin pipe 1 may be provided with a stay for attachment, a screw hole, or the like.

It does not specifically limit as a synthetic resin material which comprises the synthetic resin pipe 1, Various synthetic resins which can be injection-molded can be used. Preferably, an olefin resin such as a polypropylene resin, a thermoplastic resin such as a polyamide resin or an acrylonitrile butadiene styrene resin, a thermosetting resin such as a melamine resin, rubber, a thermoplastic elastomer, or the like can be used. The synthetic resin pipe 1 of this embodiment is formed of a polyamide resin. The synthetic resin pipe 1 is formed by injection molding as will be described later, but other molding methods such as cutting and welding may be used in combination as necessary.

A method for manufacturing the synthetic resin pipe 1 will be described. The synthetic resin pipe 1 is formed by using synthetic resin injection molding. FIG. 2 is a schematic cross-sectional view of an injection mold used for molding the synthetic resin pipe 1. The injection mold includes cavity molds CV1 and CV2 that define the outer surface shape of the synthetic resin pipe 1, and core molds CR1 and CR2 that define the inner surface shape of the synthetic resin pipe 1. In the present embodiment, the cavity molds CV1 and CV2 are configured to be mold-openable in the vertical direction in the figure. The core molds CR1 and CR2 are attached to the cavity mold, and are configured to be able to perform operations such as sliding and rotation as appropriate. A so-called cavity C is defined by the inner peripheral surfaces of the cavity molds CV1 and CV2 and the outer peripheral surfaces of the core molds CR1 and CR2, and the cavity C is filled with resin and solidified to form the synthetic resin pipe 1. Is done.

The core types CR1 and CR2 are divided into a first core type CR1 and a second core type CR2 so as to have a shape corresponding to the shape of the hole of the synthetic resin pipe 1. The first core type CR1 and the second core type CR2 are each provided along the direction in which the through hole extends, and the first core type CR1 is provided on one end side of the through hole. The division is made so that the second core type CR2 is provided on the end side.
The first core type CR1 is provided in a columnar shape. It does not have to be a strict cylinder and may have a draft angle or the like. Since the first core mold CR1 is cylindrical, the first core mold CR1 can be rotated around the central axis m in a state where the synthetic resin pipe 1 is formed.

Further, the first core mold CR1 and the second core mold CR2 are configured such that when the mold is closed, the respective end portions abut and a continuous through hole is formed in the molded pipe. Yes. Both contact | abutment is made in the position corresponding to the inside of the through-hole of the pipe shape | molded. In this embodiment, the two are in contact at the bent portion of the L-shaped through hole. The surface AS where the first core type CR1 and the second core type CR2 abut is inclined with respect to the central axis m of the first core type CR1. The angle formed by the normal of the surface AS and the central axis m is preferably 15 ° or more and 70 ° or less, and more preferably 30 ° or more and 50 ° or less.

Although detailed description is omitted, the injection mold is a cavity mold CV1, CV2 and core mold CR1, CR2, as well as a configuration necessary for a series of injection molding, for example, sprue, gate, opening / closing mechanism, guide pin, slide It has a mechanism and a protruding pin. In particular, the injection mold according to the present embodiment includes a rotation drive mechanism that rotates the core mold CR1 about the central axis, and a slide mechanism that moves the core mold CR2 in the axial direction. These mechanisms are preferably configured to rotate and move at a predetermined timing in conjunction with the opening / closing operation of the mold.

A series of steps in which the synthetic resin pipe 1 is injection molded will be described with reference to FIG.
First, an injection mold as described above is prepared. Next, the prepared mold is closed. A cavity C is formed by the cavity molds CV1 and CV2 and the core molds CR1 and CR2 (FIG. 3A).

A liquid resin is injected into the cavity C to solidify the resin, and the synthetic resin pipe 1 can be formed inside the mold. The injection and solidification of the resin may be performed by a known technique according to the type of the resin (FIG. 3B).

After the resin is injected, the core molds CR1 and CR2 are operated to rotate the first core mold CR1 around the central axis m. In the present embodiment, the pipe and the through hole to be molded have a bent shape, and the first core mold CR1 and the second core mold CR2 are in contact with each other at the inclined contact surface AS. In this state, the first core mold cannot be rotated. Accordingly, in the present embodiment, prior to the rotation of the first core mold CR1, the second core mold CR2 is slid to extract a predetermined amount, and the contact surfaces of both core molds are separated from each other. Thereafter, the first core mold CR1 is rotated around the central axis m (FIG. 3C).

By rotating the first core type CR1 about the central axis, the burr formed on the contact surface between the first core type CR1 and the second core type CR2 is made of a synthetic resin pipe by the corner of the end surface of the core type CR1. 1 is separated from the inner peripheral surface. That is, the burr and the synthetic resin pipe 1 are separated. Further, when the formed burr is small, the burr is smoothed and substantially removed by the side surface of the core type CR1. The rotation angle of the first core type CR1 is preferably 5 ° or more, more preferably 10 ° or more. If possible, it is preferable to rotate the first core type CR1 by 360 ° or more. A larger rotation angle is more effective for removing burrs. Further, it is preferable to rotate the first core type CR1 in both the right rotation and the left rotation.

In addition, it is preferable that this core type | mold rotation process is performed in the state in which cavity type | mold CV1, CV2 has not been opened yet. This is because it is possible to prevent the molded synthetic resin pipe 1 from rotating together with the first core mold CR1 and to more reliably remove burrs. If the rotation of the synthetic resin pipe 1 can be prevented, the first core type CR1 may be rotated after the cavity types CV1 and CV2 are opened.

After performing the core mold rotation process, the injection mold is completely opened. At this time, the second core mold CR2 and the first core mold CR1 are retracted to a position where there is no problem in removing the molded body, if necessary. When the mold is opened, the synthetic resin pipe 1 molded from the mold is taken out (FIG. 3D). It is preferable to blow away the removed burrs with air or the like so that they do not remain inside the synthetic resin pipe 1 or inside the mold.
By the above manufacturing method, while the molded body (synthetic resin pipe 1) is still inside the mold, the burrs generated at the contact portion of the core mold are removed from the molded body, and the burrs have no burrs. A resin pipe can be obtained.

The operation and effect of the present invention will be described.
As described above, according to the synthetic resin pipe manufacturing method of the above-described embodiment, the core types CR1 and CR2 that are configured to be divided are brought into contact with each other at the surface AS inclined with respect to the center line m of the first core type CR1. Since the cylindrical first core mold CR1 is rotated in a state where the synthetic resin pipe 1 is formed inside the mold, even if a burr occurs at the contact portion between the core molds, the first rotating Burrs are removed from the inner peripheral surface of the synthetic resin pipe by the corners of the end of the core CR1. Thereby, the burr | flash of a core type contact part can be efficiently removed inside a metal mold | die.

Further, if the predetermined amount of the second core mold CR2 is extracted prior to the rotation of the first core mold CR1, the first core mold can be rotated at a larger angle without excessively pressing the mold. As a result, burrs can be removed more efficiently. In this way, when the second core CR2 is retracted and the first core CR1 is sequentially rotated, in the bent pipe-shaped synthetic resin pipe as in the present embodiment, burrs are more efficiently removed. Done.

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.

FIG. 4 shows a synthetic resin pipe 2 having a straight pipe shape as a second embodiment. The synthetic resin pipe 2 can also be used as a connector member for connecting a rubber tube or the like. The synthetic resin pipe 2 is formed by integrally forming a square plate-like flange portion 23 at the center of a straight tubular body 21.

The synthetic resin pipe 2 of the second embodiment is also manufactured by injection molding. As shown in FIG. 5 (a), a first core mold CR3 and a second core mold CR4 are arranged for the cavity molds CV3 and CV4 that can be opened and closed in the vertical direction, respectively. When closed, a cavity is formed so that the synthetic resin pipe 2 extends in the vertical direction.

Although the surface AS where the first core type CR3 and the second core type CR4 abut is inclined with respect to the central axis m of the first core type CR3, it is the same as in the first embodiment. The first core type CR3 and the second core type CR4 are both cylindrical, and the mold is configured such that both can rotate around the central axis m.

Resin is injected into the formed cavity and solidified to form the synthetic resin pipe 2 inside the mold (FIG. 5B). Thereafter, the second core type CR4 is rotated around the central axis m together with the first core type CR3. Since both are arranged straight and both are cylindrical, they can rotate while maintaining a state where they are in contact with each other (FIG. 5C).

Due to the rotation of the first core type CR3 and the second core type CR4, the burrs generated between the core types that contact each other rotate together while being sandwiched between both core types, and the inner peripheral surface of the synthetic resin pipe 2 It is cut off and removed. Thereafter, the mold is opened and the synthetic resin pipe 2 is taken out (FIG. 5D).

Also in this embodiment, the burr | flash made into a core type contact part is efficiently removed by rotation of a core type. In particular, in this embodiment, since the burrs are rotated together with the first core type CR3 and the second core type CR4 being sandwiched, it is possible to prevent the burrs from falling down and remaining. Removal is more reliable.

In FIG. 6, the more preferable example of the form of contact | abutting of core type | molds is shown. In FIG. 6, only the vicinity of the contact portion of the core mold is shown, and other members such as a cavity mold are omitted. In this example, the core molds CR5 and CR6 for forming a hole bent at about 90 ° are brought into contact with each other at the end surfaces where the tip portions are cut off at about 45 °. These core molds can be used as a mold core mold for manufacturing a synthetic resin pipe having a bent pipe shape shown in FIGS. The first core type CR5 has a cylindrical shape, and the second core type CR6 has a prismatic shape.

In the portion where the first core mold CR5 and the second core mold CR6 abut each other, the outer shape E5 of the surface on the first core mold side is elliptical, and the outer shape E6 of the surface on the second core mold side is rectangular. is there. Further, the outer shape E6 of the surface on the second core mold side is larger than the outer shape E5 of the surface on the first core mold side, and when the core molds come into contact with each other, the surface on the first core mold side The outer shape E5 is inside the outer shape E6 of the surface on the second core mold side.

With such a configuration, when the second core type CR6 is retracted prior to the rotation of the first core type CR5, the space formed around the end face of the first core type CR5 increases, and the first core The mold CR5 can be rotated at a larger angle without interfering with the inner peripheral surface of the molded synthetic resin pipe, and burrs can be removed more efficiently.

Further, as in the present embodiment, if the second core type to be retracted in advance is a prismatic shape, the first core type CR5 may be rotated 360 ° after the second core type is retracted. Since it does not interfere with the inner peripheral surface of the molded synthetic resin pipe, burrs can be removed more efficiently.

In the said embodiment, a various mechanism etc. can be utilized for rotation of a 1st core type | mold or a 2nd core type | mold, and a rotation means is not specifically limited. For example, the first core type and the second core type may be rotated by a mechanism combining a motor and a gear, and the motor may be an electric motor or a hydraulic motor. A rotation mechanism may be configured by combining a gear mechanism with an electromagnet, an air cylinder, a hydraulic cylinder, or the like. In addition, using a cam, guide groove, spiral groove, slide mechanism, gear, etc., the mechanism that converts the opening / closing operation of the mold and the operation of other slide mechanisms into the core-type rotation operation is used. The mold may be rotated.

The synthetic resin pipe according to the present invention is not limited to a pipe made of only pipes. For example, like the synthetic resin pipe 2 of FIG. 4, you may have a flange. FIG. 7 shows another example of the synthetic resin pipe. In the synthetic resin pipe 3 of this embodiment, an annular protrusion 33 is formed at one end of a pipe portion 31 formed in a bent tube shape, and a cap 34 is provided at the other end of the pipe portion 31. It is integrally molded. The cap 34 can be a bottle or a container lid. Thus, other members may be integrally formed with the synthetic resin pipe.

The specific use of the synthetic resin pipe is not particularly limited. The synthetic resin pipe can be used as a connector member for connecting a rubber tube or a synthetic resin tube, and the synthetic resin pipe can also be used as a hose connection member. Alternatively, a synthetic resin pipe can be used as a connector member of a pressure transmission circuit such as a hydraulic circuit or a pneumatic circuit. In these applications, a seal groove may be provided in the synthetic resin pipe, or the seal member may be integrally formed.

According to the synthetic resin pipe manufacturing method, various synthetic resin pipes can be efficiently manufactured by using injection molding, and the industrial utility value is high.

DESCRIPTION OF SYMBOLS 1 Synthetic resin pipe 11 1st tubular part 12 2nd tubular part 13 Annular protrusion CV1, CV2 Cavity type CR1 1st core type CR2 2nd core type C Cavity AS Contact surface m Center axis

Claims (5)

A synthetic resin pipe manufacturing method using injection molding,
Having a step of preparing an injection mold,
The injection mold has a cavity mold that defines the outer surface shape of the synthetic resin pipe and a core mold that defines the inner surface shape of the synthetic resin pipe,
The core mold is divided into a first core mold and a second core mold that are provided along the hole of the pipe and are in contact with each other, and at least the first core mold is cylindrical.
The surface where the first core mold and the second core mold abut when the mold is closed is inclined with respect to the central axis of the first core mold,
Following the mold preparation process, the injection mold is closed, and an injection process is performed to inject and fill synthetic resin into the mold cavity.
Subsequent to the injection step, performing a step of rotating the first core mold around the central axis,
A method for producing a synthetic resin pipe, comprising a step of taking out a synthetic resin pipe molded from a mold following the core mold rotation process. The method for producing a synthetic resin pipe according to claim 1, wherein a predetermined amount of the second core mold is extracted prior to the rotation of the first core mold. The method for producing a synthetic resin pipe according to claim 2, wherein the synthetic resin pipe has a bent pipe shape. When the first core mold and the second core mold are in contact with each other, the outer shape of the surface on the second core mold side is larger than the outer shape of the surface on the first core mold side. The method for producing a synthetic resin pipe according to claim 2 or 3, wherein the outer shape of the surface on the first core mold side is inside the outer shape of the surface on the second core mold side. The synthetic resin pipe is straight and the second core type is also cylindrical.
The method for producing a synthetic resin pipe according to claim 1, wherein, in the core mold rotating step, the second core mold is rotated together with the first core mold.

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