JPH10175237A - Mold for injection molding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent formation of a pinhole at a synthetic resin layer in the case of manufacturing a tube joint lined by synthetic resin on an inner periphery of a T-shaped steel tube. SOLUTION: First and second main cores 10, 20 are inserted at a predetermined interval over the entire length of a main tube 51 of a straight tube state into a T-shaped steel tube 50 provided with a branch tube 52 branched perpendicularly to the tube 51, and a branch core 30 is inserted at a predetermined interval over the entire length of the tube 52. A sprue 31 provided at an axial center of the core 30 is in communication within the tube 50 via a pair of gates 33 extended in a circumferential direction of the cores 10, 20. Molten resin flowed out of the gates 33 are fed along a circumferential direction of the cores 10, 20, combined at high pressure at axisymmetrical positions of the cores 10, 20 to prevent air entraining.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mold used for manufacturing a T-shaped tubular article by injection molding.
In particular, a pipe joint (cheese) in which the inner peripheral surface of a T-shaped steel pipe having a flange at each end face is lined with a synthetic resin.
The present invention relates to a metal mold for injection molding suitably used for producing a mold.

[0002]

2. Description of the Related Art A composite pipe in which the inner peripheral surface of a steel pipe is lined with a synthetic resin is used as a pipe for supplying water and a pipe for supplying a chemical solution in a factory facility. When connecting such composite pipes, a resin-lined pipe joint whose inner peripheral surface is lined with a synthetic resin is used to connect the composite pipes.

[0003] A T-shaped resin-lined pipe joint (cheese) used for piping of a composite pipe usually has a branch pipe section perpendicular to the main pipe section at the center in the longitudinal direction of a main pipe section having a straight tubular shape. The inner peripheral surface of a T-shaped steel pipe branched into a rectangular shape is lined entirely with a synthetic resin. Flanges are attached to each end face of the main pipe section and an end face of the branch pipe section of the steel pipe by welding, respectively, and the inner peripheral portion of the end face of each flange section is also lined with synthetic resin. In order for the synthetic resin lining each flange to cover the end face of the steel pipe of the composite pipe connected to the pipe joint, the steel pipe is
There is no danger of rusting or corroding on contact with water or chemicals.

[0004] Such a resin-lined pipe joint with a flange is usually manufactured using an injection mold shown in FIG. In this injection molding die, a steel pipe 50 constituting a pipe joint is used as an outer die. The steel pipe 50 is formed in a T-shape by branching the branch pipe section 52 perpendicularly to the main pipe section 51 at the center in the longitudinal direction of the straight tubular main pipe section 51. The diameter of the main pipe part 51 in the steel pipe 50 is set to, for example, 50 mm.
The diameter of No. 2 is set to 40 mm.

[0005] In the steel pipe 50, a T-shaped core 70 is disposed concentrically with a constant distance from the inner peripheral surface of the steel pipe 50. The core 70 is formed of a pair of cylindrical main cores 71 that are inserted into the respective sides of the main pipe 51 of the steel pipe 50.
And a columnar branch core 73 inserted through the branch pipe 52 of the steel pipe 50. Each main core portion 71 includes a main tube portion 51.
Are concentrically inserted with a constant interval from the inner peripheral surface of each side of the main core 71, and are integrally connected by a bolt 75 inserted into the axial center of one main core 71. . The distal end surfaces of the main core portions 71 abut against each other at the central portion in the longitudinal direction of the main pipe portion 51, and are in a pressed state.

The distal end surface of the branch core portion 73 inserted into the branch pipe portion 52 of the steel pipe 50 is in a semi-cylindrical concave state, and the distal end surfaces of the main core portions 71 project from each other. It is fitted over the fitted tip. A sprue 74 through which the synthetic resin in a molten state flows is provided at the axial center of the branch core 73. The branch core 73
A pair of gates 76 for allowing the molten resin flowing through the sprue 74 to flow into the steel pipe 50 are provided at the distal end of the branch core 73.
, That is, along the axial direction of each main core portion 71.

A flange mold 77 is fitted to each base end of each of the main core portion 71 and the branch core portion 73, and is fixed in a state in which it abuts against the end surface of each flange portion 53 of the steel pipe 50. Have been. Flange mold 7 attached to each end of main pipe part 51 in steel pipe 50
7 is a main core portion 71 inserted into the main pipe portion 51 of the steel pipe 50.
Are held concentrically with respect to the main pipe portion 51, and the flange mold 77 attached to the end of the branch pipe portion 52 has a branch core portion 73 that passes through the inside of the branch pipe portion 52 of the steel pipe 50. Are held concentrically with respect to the branch pipe portion 52.
In the flange mold 77, the distal end face of the branch core 73 is pressed against the distal end of each main core 71.

In the injection mold having the above-described structure, a molten synthetic resin is supplied to a sprue 74 provided at the axial center of the branch core 73. The molten resin supplied to the sprue 74 passes through each gate 76 and passes through the steel pipe 5
0, and is filled between the steel pipe 50 and each of the main core portions 71 and the branch core portions 73. Then, after the molten resin filled in the steel pipe 50 is hardened, each flange mold 77 is removed from the steel pipe 50, and each of the main core portions 71 and the branch core portions 73 are removed from the steel pipe 50. A resin-lined pipe joint (cheese) with a flanged shape is obtained.

[0009]

In the injection molding die shown in FIG. 4, the molten resin passing from the sprue 74 of the branch core 73 to the gate 76 flows from the center of the main pipe 51 of the steel pipe 50 to each end. While flowing along the axial direction toward the portion and flowing along the axial direction of each main core portion 71, it also flows along the circumferential direction of each main core portion 71. Then, the molten resin flows in the circumferential direction of each main core portion 71 while flowing along the axial direction of each main core portion 71, so that the molten resin flows between the main pipe portion 51 of the steel pipe 50 and the main core portion 71. Is filled. Then, while the main pipe 51 is filled with the molten resin, the branch pipe 52 and the branch core 73 are also filled with the molten resin.

When the main tube 51 is filled with the molten resin, the molten resin flowing out of each gate 76 flows along the circumferential direction while branching to each side of each main core 71. And each main core portion 7 with which the branch core portion 73 is abutted.
The branched molten resin merges with the peripheral surface portion 1 at the axially symmetric peripheral portion of the main core portion 71. At this time, the molten resin flowing along the peripheral surface portion of each main core portion 71 flows to each end of the main core portion 71, and therefore, the axial center symmetry of the main core portion 71 with respect to each gate 76. At the position, the branched molten resins merge without applying a large pressure. Therefore, when the molten resins join, there is a possibility that air may be drawn into the molten resin.
The air entrained in the molten resin passes through the pinhole to form a pinhole in the synthetic resin layer lining the inner peripheral surface of the main pipe portion 51 of the steel pipe 50, and the air flows into the main pipe portion 51 of the steel pipe 50, Contact with water, chemicals, etc.
1 may rust or corrode.

The present invention has been made to solve such a problem, and an object of the present invention is to eliminate the possibility that air is entrained in a molten resin filled in an outer mold, and therefore, a T resin molded by injection molding. An object of the present invention is to provide an injection molding die that does not have a risk of forming a pinhole in a letter-shaped molded product.

[0012]

According to the injection molding die of the present invention, a branch pipe portion is provided at a central portion in the longitudinal direction of a main pipe portion having a straight tubular shape, and the branch pipe portion branches substantially perpendicularly to the main pipe portion. A T-shaped outer die, and a branch core inserted into the central portion of the main core portion of the outer die at an appropriate interval over the entire length thereof, and a branch core inserted at an appropriate interval over the entire length of the branch portion. A T-shaped core formed by abutting the ends of the parts, a sprue through which the molten resin flows is provided at the axial center of the branch core part, and the sprue and the outer mold are provided. A pair of gates extending along the circumferential direction of each main core portion are provided at the distal end so as to communicate with the inside.

[0013]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a sectional view showing an example of an embodiment of an injection mold according to the present invention. This injection molding die is used for manufacturing a T-shaped flanged resin-lined pipe joint (cheese) shown in FIG.
In this resin-lined pipe joint with a flange, the inner peripheral surface of the T-shaped steel pipe 50 is lined with a synthetic resin layer 60 over the entire circumference. The steel pipe 50 has a main pipe part 51 extending linearly, and a branch pipe part 52 branched from the central part in the longitudinal direction of the main pipe part 51 so as to be perpendicular to the main pipe part 51. A flange 53 is attached to each end of the main pipe 51 by welding.
The flange portion 5 is also provided at the tip end of the branch pipe portion 52 extending from
3 are attached by welding.

The synthetic resin layer 60 lines the entire inner peripheral surface of the main pipe part 51 and the inner peripheral surface of the branch pipe part 52 of the steel pipe 50. The inner peripheral side portion of the end surface and the inner peripheral side portion of the end surface of the flange portion 53 provided on the branch pipe portion 52 are respectively covered.

Such a resin-lined pipe joint with a flange is manufactured by injection molding using the injection mold of the present invention shown in FIG. 1 using a T-shaped steel pipe 50 as an outer mold. This injection molding die is a T-shaped steel pipe 50 serving as an outer die, which is inserted concentrically at a predetermined interval into a T-shaped steel pipe 50.
It has a character-shaped core 1.

The core 1 has a cylindrical first main core portion 10 and a cylindrical main main portion 20 inserted concentrically into each side of a main pipe portion 51 of a steel pipe 50 constituting an outer die.
And a columnar branch core 30 which is inserted concentrically into the branch pipe 52 of the steel pipe 50.

First main core section 10 and second main core section 20
Penetrates the inside of each side of the main pipe portion 51 of the steel pipe 50 over the entire length thereof at a constant interval from the inner peripheral surface of each side portion. Are mutually butted at the center in the longitudinal direction. The other base end of each of the first main core portion 10 and the second main core portion 20 extends outward from a flange portion 53 provided at each end of the main pipe portion 51.

The first main core portion 10 located in the main pipe portion 51
A cylindrical boss portion 11 protruding toward the distal end surface of the second main core portion 20 abutting against the distal end surface is provided along the axial center portion. A concave portion 21 into which the boss portion 11 is fitted is provided in the axial center portion of the distal end surface of the second main core portion 20 located inside. The first main core portion 10 and the second main core portion 20 are positioned concentrically with each other by the boss portion 11 being fitted into the concave portion 21.

A bolt insertion hole 12 penetrates through the entire length of the shaft of the first main core portion 10. The bolt insertion hole 12 penetrates through the axis of the boss 11 and opens at the tip end surface of the boss 11. Also, the second main core unit 20
The female screw hole 22 opening on the bottom surface of the concave portion 21 is provided along the axial center portion at the distal end portion where the concave portion 21 is provided.

First main core section 10 and second main core section 20
The distal end of the bolt 15 inserted into the bolt insertion hole 12 of the first main core portion 10 is screwed to the female screw hole 22 of the second main core portion 20, so that they are concentrically integrated with each other. It is to be connected to.

The branch core portion 30 is inserted into the branch tube portion 52 of the steel pipe 50 in a concentric manner with a constant interval over the entire length thereof, and the tip surface thereof is depressed in a semi-cylindrical shape. ing. The tip surfaces of the branch core portions 30 that are recessed in a semi-cylindrical shape are fitted between the mutually butted tip portions of the first main core portion 10 and the second main core portion 20, and are attached to the respective outer peripheral surfaces. Matched. The base end of the branch core 30 extends outward from the branch pipe 52 of the steel pipe 50.

A sprue 31 through which the molten resin flows is provided at the axial center of the branch core 30 over the entire length. Further, a pair of gates 33 extending along the circumferential direction of the first main core portion 10 and the second main core portion 20 are provided at the tip of the branch core portion 30 so as to face each other. Each of the gates 33 is formed in a groove shape that is opened at a tip end surface of the branch core portion 30 that is recessed in a semi-cylindrical shape.
The sprue 31 and the inside of the main pipe part 51 of the steel pipe 50 communicate with each other through the branch core part 30 in the radial direction. First main core unit 1
The opening of each gate 33 extending along the circumferential direction of the first and second main core portions 20 is such that the branch core portion 30 is
And when it abuts against the outer peripheral surface of the distal end portion of the second main core portion 20, it is in a state of being covered by each outer peripheral surface.

The first steel pipe 50 inserted into the main pipe part 51
A flange mold 40 is fitted and fixed to each of the base ends of the main core portion 10 and the second main core portion 20, and the branch core inserted into the branch pipe portion 52 of the steel pipe 50. The flange mold 40 is fitted and fixed to the base end of the part 30. Each flange mold 40 is provided with a flange 53 provided on a main pipe 51 and a branch pipe 52 of a steel pipe 50.
Butted against the end face of The first main core portion 10, the second main core portion 20, and the branch core portion 3 are provided on an end face of each flange mold 40 facing each flange portion 53.
Notches 41 are provided so as to be cut along the circumference of 0.

When assembling the injection mold having such a configuration, first, the main pipe portion 51 of the steel pipe 50 to be the outer mold is used.
The first main core portion 10 and the second main core portion 20 are respectively inserted thereinto, and the boss 11 provided on the distal end surface of the first main core portion 10 is inserted into the concave portion 21 of the second main core portion 20. Insert
The first main core portion 10 and the second main core portion 20 are in a state where the respective distal end surfaces are abutted with each other. In such a state, the bolt 1 is inserted into the bolt insertion hole 12 of the first main core 10.
5 and insert the male thread at the tip of the bolt 15 into the second
It is screw-coupled to a female screw part 22 provided at the tip of the main core part 20. Thereby, the tip surfaces of the first main core portion 10 and the second main core portion 20 are integrally connected in a state where they are pressed against each other.

Thereafter, the branch core section 30 is inserted into the branch pipe section 52 of the steel pipe 50, and the semi-cylindrical tip surface is fixed to the outer periphery of the distal end of the first main core section 10 and the second main core section 20. Face to face.

Each of the base ends of the first main core section 10, the second main core section 20, and the branch core section 30 is provided with a flange mold 4
0 are fitted to each other, and fixed in a state where they abut against each flange portion 43 of the steel pipe 50. Thereby, the first main core 10 and the second main core 20 are connected to the main pipe 51 of the steel pipe 50.
The branch core portion 30 is held in the branch pipe portion 52 of the steel pipe 50 in a concentric state with a fixed interval. Then, the branch core portions 30 are pressed against the outer peripheral surfaces of the distal ends of the first main core portion 10 and the second main core portion 20.

When the injection mold is assembled in this manner, the synthetic resin in a molten state is supplied to the sprue 31 of the branch core 30. The molten resin flowing through the sprue 31 flows into the steel pipe 50 through each of the gates 33 provided at the tip of the branch core portion 30. In this case, since each gate 33 is provided along the circumferential direction of the first main core portion 10 and the second main core portion 20, the molten resin flowing out of each gate 33 flows into the main pipe portion 51 of the steel pipe 50. The first main core portion 10 and the second
Along the circumferential direction of the main core portion 20, the first main core portion 10 flows while flowing in a branched state.
And it flows along the axial direction of the second main core portion 20.

As described above, the molten resin flowing out of each gate 33 first flows through each side of the first main core portion 10 and the second main core portion 20 in the circumferential direction. Are the first main core unit 10 and the second main core unit 20
The molten resin surely flows to the axially symmetric outer peripheral surface portion, and the molten resin merges at a high pressure in the outer peripheral surface portion. Therefore, the molten resin branched and flowing along each side of each of the first main core portion 10 and the second main core portion 20 with respect to each gate 33 flows into the first main core portion 10 and the second main core portion 20.
There is no possibility that air will be trapped inside the outer peripheral surface of the main core portion 20 symmetrical with respect to the axial center.

As described above, while the molten resin flows along the circumferential direction of the first main core portion 10 and the second main core portion 20, the axis of the first main core portion 10 and the second main core portion 20 is increased. By flowing along the direction, the main pipe portion 5 of the steel pipe 50 is formed.
1 and the space between the first main core 10 and the second main core 20. While the main pipe portion 51 is filled with the molten resin, the molten resin flowing into the branch pipe portion 52 from each of the gates 33 provided at the two axially symmetrical positions of the branch core portion 30 is the branch core portion. While flowing along the axial direction of the portion 30, it flows in the circumferential direction and fills the branch pipe portion 52.

As described above, when the molten resin is filled between the steel pipe 50 and the first main core portion 10, the second main core portion 20, and the branch core portion 30 and hardened, each flange mold 4
0 is removed from the steel pipe 50, and the first main core 10, the second main core 20, and the branch core 30 are removed from the steel pipe 50. Thereby, a resin-lined pipe joint with a flange in which the inner peripheral surface of the steel pipe 50 is lined with the synthetic resin layer 60 over the entire circumference is obtained.

In the resin-lined pipe joint with a flange manufactured as described above, since no pinhole is formed in the synthetic resin layer 60, water, chemicals, etc. flowing through the synthetic resin layer 60 are removed from the steel pipe. There is no danger of contact with the inner peripheral surface of 50. Therefore, corrosion of the steel pipe 50 is prevented, and the resin-lined pipe joint with a flange is stably used for a long time.

[0033]

As described above, in the injection mold of the present invention, since the gates provided on the branch cores are in a state along the main cores, the circumferential direction of the main cores is large. The molten resin that flows in a state of branching along the gate merges with each gate at a high pressure state at an axially symmetric position of the main core portion. Therefore,
There is no possibility that air is entrained in the molten resin at an axially symmetric position of the main core with respect to each gate. As a result, there is no possibility that a pinhole is formed in the formed synthetic resin layer, and the quality of the molded product is significantly improved.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing an example of an embodiment of an injection mold according to the present invention.

FIG. 2 is a longitudinal sectional view of a flanged lining pipe joint manufactured by the injection molding die.

FIG. 3 is a longitudinal sectional view of a branch core used in the injection molding die.

FIG. 4 is a cross-sectional view showing an example of a conventional injection mold.

[Explanation of symbols]

 Reference Signs List 1 core 10 first main core portion 11 boss portion 12 bolt insertion hole 15 bolt 20 second main core portion 21 concave portion 22 female thread portion 30 branch core portion 31 sprue 33 gate 40 flange type 50 steel pipe 51 main pipe part 52 branch pipe part 53 flange Department

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI B29L 23:00

Claims (1)

[Claims] 1. A T-shaped outer die provided with a branch pipe branching substantially perpendicularly to the main pipe at the longitudinal center of the straight main pipe, and an outer die main pipe. At the center of the main core, which is inserted at appropriate intervals over its entire length,
A core formed in a T-shape by abutting the ends of branch cores that are inserted into the branch pipe at appropriate intervals over the entire length thereof, and a molten resin flows through the branch core. The sprue is provided at the shaft center portion, and a pair of gates extending along the circumferential direction of each main core portion are provided at the tip end portion so as to communicate the sprue and the inside of the outer mold. Mold for injection molding.