JP3285699B2 - Method for producing inner surface resin lining reducer and injection mold used for this method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an inner resin lining reducer having a resin running layer formed from the inner surface of a metallic reducer body to the tube end flange surface, and an injection mold used in the manufacturing method. About.

[0002]

2. Description of the Related Art Generally, in a resin joint with a flanged inner resin lining, from the viewpoint of preventing corrosion of a metal pipe, etc.
It is necessary to form the lining layer so that the resin is present without interruption from the inner surface to the pipe end flange surface, and it is required that the lining layer does not peel or crack due to a temperature change or the like after piping.

As a method of manufacturing this type of flanged lining pipe joint (or pipe), for example, the following method is conventionally known. One is JP-A-49-99.
No. 370. This is done by inserting a resin pipe into a flanged steel pipe, projecting its end by a predetermined amount from the steel pipe, and rotating the cone-shaped jig into the protruding part of the resin pipe in a heated state to rotate the resin pipe. After the pipe end face is formed in a trumpet shape, the flange turn-up portion formed in the trumpet shape is brought into close contact with the steel pipe flange portion while being reheated by a pressing plate.

Another one is disclosed in Japanese Patent Application Laid-Open No. 54-2938.
No. 2 discloses this. This is done by inserting a resin pipe into a flanged steel pipe, projecting its end from the steel pipe by a predetermined amount, passing a heating liquid through the resin pipe in that state, and softening the heating liquid. The resin flange portion is brought into close contact with the steel pipe flange portion by expanding and molding the portion to a diameter larger than the outer diameter of the steel pipe flange surface.

[0005]

However, Japanese Patent Application Laid-Open No.
In the methods described in JP-A-9-99370 and JP-A-54-29382, it is inevitable that residual stress is generated when a resin lining layer on a flange surface is manufactured by thermal processing. During repeated thermal expansion and contraction of the resin, there is a possibility that the resin portion may peel off due to the influence of residual stress. Another problem is that it takes time to form and finish the resin lining layer on the flange surface.

In order to solve the above-mentioned problems, the present inventors used a metal tube as one of the molds, and applied the metal tube from the inner surface to the tube end flange surface. A manufacturing method (Japanese Patent Application No. 5-160765) in which another mold for forming a cavity for forming a lining layer is set between the mold and a metal tube, and a resin is injected into the cavity to form a lining layer. Proposed earlier.

According to this method, the inner resin lining step and the flange forming step, which were conventionally performed separately, can be performed in one step, and only the gate cut is performed in the finishing step by employing injection molding. It suffices to make it very simple. In addition, since no residual stress is generated at the time of molding, the obtained inner resin lining tube does not have a possibility that the resin lining layer is peeled off even if thermal expansion and contraction due to temperature fluctuations are repeated after the piping.

[0008] However, when an attempt is made to manufacture an inner resin lining reducer using this manufacturing method,
There were the following problems. That is, the reducer has a large diameter portion and a small diameter portion, and the combination of the diameters of the large diameter portion and the small diameter portion covers a considerable variety. Therefore, in order to manufacture an inner running reducer using the method proposed above, a different inner rod type must be prepared for each combination.

By the way, a sprue and a runner must be provided in a mold for injection molding, and processing of such a sprue and a runner is the most expensive in the production cost of the mold. Therefore, if sprues and runners are provided for all types of dies as described above, the manufacturing cost becomes extremely high. In view of such circumstances, the present invention can be used for a method of manufacturing an inner surface resin lining reducer that can be formed at low cost as well as forming a resin lining layer on the inner surface by injection molding, and is used in this manufacturing method. It is intended to provide an injection mold.

[0010]

In order to achieve the above object, a method of manufacturing an inner resin lining reducer according to the invention of claim 1 (hereinafter referred to as "first invention") is to provide a large diameter resin lining reducer. Part and a small diameter part at both ends, the large diameter part and the small diameter part are integrated through a connecting part that gradually reduces in diameter from the large diameter part side to the small diameter part side, and the end part of the large diameter part and the small diameter part A metallic reducer body having a flange formed at each end of the portion is used as one of the molds, and the reducer body is connected to the reducer body from the inner surface to the tube end flange surface. A method of manufacturing an inner resin lining reducer in which another mold for forming a cavity for forming a lining layer is set therebetween, and a resin is injected into the cavity to form a lining layer. Said portion facing the reducer within the body of the mold with a surfactant or freely split separated at the small diameter portion side of the interface between the connecting portion and the small diameter portion of,
A sprue and a runner are provided in the split mold on the small diameter portion side, and the molten resin is injected into the cavity through the split mold on the small diameter portion side.

On the other hand, the injection mold according to the invention of claim 2 (hereinafter, referred to as "second invention") has a large diameter portion and a small diameter portion at both ends, and the large diameter portion and the small diameter portion are separated from each other. A metal reducer body that is integrated through a connecting portion that gradually reduces in diameter from the large diameter portion side to the small diameter portion side, and has a flange formed at an end of the large diameter portion and an end of the small diameter portion, This is an injection molding die used to manufacture an inner resin line reducer by lining the resin by injection molding from the inner surface to the pipe end flange surface, and it is fastened to the flanges at both ends and has a flange surface between the flange surfaces. And two flange dies forming a partial cavity for use, and a flange dies on the large diameter portion side are fitted so as to be displaceable in the tube axis direction of the reducer body, and are connected via a connection portion from the large diameter portion or a connection portion from the large diameter portion. Part of the small diameter part A large-diameter-side inner surface rod type that forms a large-diameter-side partial cavity that is continuous with the large-diameter-side flange surface partial cavity between the inner surface of the reducer main body and a reducer main body that is a small-diameter portion-side flange type A small-diameter portion partial cavity that is continuous with the small-diameter portion flange surface partial cavity and the large-diameter portion partial cavity is formed between the small-diameter portion and the inner surface of the reducer body. A small-diameter portion side inner rod type,
A sprue and a runner for injecting the resin into the cavity are formed in the small diameter portion side inner rod type.

In the above structure, the reducer body is usually made of steel, but other metals such as cast metal and stainless steel may be used. The resin to be the lining layer is not particularly limited as long as it can be injection-molded. For example, vinyl chloride resin, chlorinated vinyl chloride resin, polyethylene, polybutene, polyvinylidene fluoride (PVDF),
Resins such as polyphenylene sulfide (PPS) are exemplified.

Further, in manufacturing, an adhesive is usually used from the inner surface of the reducer main body to the pipe end flange surface, but the present invention can be applied to a loose lining that does not use such an adhesive. When using an adhesive, a hot-melt adhesive is usually used, but a solvent-based adhesive such as a rubber adhesive can also be used.

[0014]

According to the structure of the first aspect of the present invention, for example, a split mold for the large diameter portion and a split mold for the small diameter portion are selected according to the large diameter portion and the small diameter portion of the reducer body. When mounted on the reducer main body as a mold, a cavity is formed between the reducer main body and the other molding die, and the molten resin is injected into the cavity through a sprue and a runner formed in the split mold on the small diameter side. Upon injection, a desired resin lining layer is formed from the inner surface of the reducer body to the tube end flange surface.

Further, since the split mold on the small diameter portion side has the same diameter in the longitudinal direction, even if the diameter on the large diameter portion side of the reducer body changes, if the diameter on the small diameter portion does not change, the sprue and It can be used as it is without changing the split mold on the small diameter portion side where the runner is provided. On the other hand, according to the configuration of the second invention, in addition to the above operation, even if the length of the large diameter portion or the small diameter portion of the reducer main body changes, the inner rod type is relatively displaced in the pipe axis direction to the flange type. Can be dealt with by changing the degree of fitting.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the drawings showing the embodiments. FIG. 1 shows an embodiment of the injection mold according to the second invention, and shows its disassembled state in cross section, and FIG. 2 shows its assembled state in cross section. As shown in the figure, the injection mold 1 includes two flange dies 2 and 3, an inner rod die 4 for a large diameter part, and an inner rod die 5 for a small diameter part.

As shown in FIG. 2, the two flange dies 2 and 3 have a large-diameter flange 62 provided on the large-diameter portion 61 and a small-diameter flange 64 provided on the small-diameter portion 63 of the reducer body 6, respectively. And when bolted to the flanges 62 and 64, respectively, the flange surface partial cavities 71 and 72 can be formed with the flange surfaces.

The large-diameter portion inner rod mold 4 is adapted to be fitted to the large-diameter portion side flange mold 2 so as to be displaceable in the tube axis direction of the reducer main body 6 and the end face thereof is provided on the reducer main body 6. When the interface between the connecting portion 65 and the small-diameter portion 63 coincides with each other, a large-diameter portion partial cavity 73 is formed between the connecting portion 65 and the reducer main body 6. The large diameter portion cavity 73 is connected to the flange surface portion cavity 71 on the large diameter portion 61 side.

The small-diameter portion inner rod mold 5 is fitted to the small-diameter portion side flange mold 3 so as to be displaceable in the tube axis direction of the reducer main body 6, and the end faces thereof are connected to the connecting portion 65 of the reducer main body 6 and the small-diameter portion 63. At the time of coincidence with the interface, a small-diameter portion partial cavity 74 is formed between the reducer main body 6. The small-diameter portion partial cavity 74 is connected to the large-diameter portion partial cavity 73 and the flange-surface partial cavity 72 on the small-diameter portion 63 side.

That is, the cavity 7 serving as the resin lining layer is formed by the partial cavities 71 and 72 for the flange surface, the partial cavity 73 for the large diameter portion, and the partial cavity 74 for the small diameter portion. The small-diameter portion inner rod die 5 is provided with a sprue 51 and a runner 52.

Next, a method for manufacturing the inner resin lining reducer of the first invention using the injection mold 1 will be described in detail. That is, in this manufacturing method, as shown in FIG. 2, the reducer body 6 is used as one of the molds, and the flange molds 2 and 3 are each
Attach to 2, 64. Then, the inner rod mold 4 for the large diameter part and the inner rod mold 5 for the small diameter part are fitted to the flange molds 2 and 3 respectively, and their end faces are brought into close contact with the interface between the connecting part 65 and the small diameter part 63.

By mounting the flange dies 2 and 3, the large diameter portion inner rod 4 and the small diameter portion inner rod 5 on the reducer body 6, the flange dies 2, 3,
Internal rod type 4 for large diameter part and internal rod type 5 for small diameter part
A cavity 7 is formed between them. Next, the sprue 51 provided in the small-diameter portion inner rod mold 5 in the cavity 7,
The resin is injected through the runner 52 to fill the cavity 7 with the resin.

After the resin is cooled and hardened, the flange dies 2 and 3, the large-diameter portion internal rod die 4 and the small-diameter portion internal rod die 5 are removed to obtain an inner resin lining reducer. That is, according to the manufacturing method of the first invention, the inner resin lining step and the flange forming step which were conventionally performed separately can be performed in one step, and the gate is formed in the finishing step by adopting injection molding. Since only cutting is required, it becomes very simple, and thermal stress does not occur during molding, and the obtained inner resin lining pipe has residual stress even if thermal expansion and contraction due to temperature fluctuations are repeated after piping. There is no possibility that the resin lining layer is peeled off due to the influence of the above.

The inner rod type is divided into an inner rod type 4 for a large diameter part and an inner rod type 5 for a small diameter part.
The sprue 51 and the runner 52 are attached to the inner rod type 5 for the small diameter portion.
Provided, the number of types of the internal rod type provided with the sprue and the runner 52 can be reduced, and many different types of inner surface resin lining reducers can be provided at low cost.

On the other hand, according to the injection molding die of the second invention, in addition to the above-mentioned effects, the large-diameter portion internal rod die 4 and the small-diameter portion internal rod die 5 are respectively connected to the flange dies 2 and 3 by the reducer body. 6, the large diameter portion 61 of the reducer body 6 is fitted so as to be displaceable in the tube axis direction.
Alternatively, even if the length of the small diameter portion 63 changes, it can be dealt with only by one internal rod type 4 (5). Therefore,
Various types of inner resin lining reducers can be provided at lower cost.

[0026]

According to the structure described above, the first
The method of manufacturing an inner resin lining reducer according to the invention requires a small number of split dies with sprues and runners corresponding to the number of diameters on the small diameter side. Can be manufactured.

Of course, the inner resin lining process and the flange portion forming process, which were conventionally performed separately, can be performed in one process, and only the gate cut needs to be performed in the finishing process by using injection molding. In addition to being very simple, there is no possibility that the resin portion of the obtained inner resin lining pipe will peel off due to residual stress during repeated thermal expansion and contraction due to temperature fluctuations after the piping.

On the other hand, in addition to the above effects, the injection molding die according to the second aspect of the present invention can accommodate one inner lot type even if the inner resin lining reducer has different lengths of the large diameter portion and the small diameter portion. Therefore, many types of inner surface resin lining reducers can be manufactured at lower cost.

[Brief description of the drawings]

FIG. 1 is an exploded sectional view of an injection mold according to the present invention.

FIG. 2 is a cross-sectional view of a state in which the injection mold according to the present invention is combined with a reducer body.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 Injection molding die 2 Flange die 3 Flange die 4 Internal rod type for large diameter part 5 Internal rod type for small diameter part 6 Reducer body 7 Cavity 51 Sprue 52 Runner 61 Large diameter part 62 Flange 63 Small diameter part 64 Flange 65 Connecting part 71 Cavity for flange surface 72 Cavity for flange surface 73 Cavity for large diameter part

Claims (2)

(57) [Claims] A large-diameter portion and a small-diameter portion are provided at both ends, and the large-diameter portion and the small-diameter portion are integrated via a connecting portion that gradually decreases in diameter from the large-diameter portion side to the small-diameter portion side. Using a metal reducer body in which a flange is formed at the end of the diameter part and the end of the small diameter part, respectively, as one molding die,
The other mold for forming a cavity for forming a lining layer between the reducer body and the reducer body is set from the inner surface to the tube end flange surface of the reducer body, and a resin is injection-molded into the cavity. A method for manufacturing an inner resin lining reducer that forms a lining layer by using a part facing the reducer body of the other mold at an interface between the small diameter part and the connection part or at a smaller diameter part side than this interface. An inner resin lining reducer characterized by being a split mold that is separable, providing a sprue and a runner in the split mold on the small diameter part side, and injecting the molten resin into the cavity through the split mold on the small diameter part side. Manufacturing method. 2. A large diameter portion and a small diameter portion are provided at both ends, and the large diameter portion and the small diameter portion are integrated through a connecting portion that gradually reduces in diameter from the large diameter portion side to the small diameter portion side. The inner resin line reducer is manufactured by lining the resin by injection molding from the inner surface to the tube end flange surface of the metallic reducer body having flanges formed at the end of the diameter portion and the end of the small diameter portion, respectively. An injection molding die used in the case where two flange dies are fastened to the flanges at both ends to form a partial cavity for the flange surface between the flange dies and a flange die on the large diameter portion side. Between the large diameter portion and the inner surface of the reducer body extending from the large diameter portion to the connecting portion or from the large diameter portion to the part of the small diameter portion through the connecting portion. With partial cavity for flange surface The inner surface of the reducer body of the small diameter portion, which is displaceably fitted in the tube axis direction of the reducer body to the large diameter portion side inner surface rod type forming the large diameter portion side partial cavity and the small diameter portion side flange type. And a small-diameter-part-side inner rod mold that forms a small-diameter-part-side partial cavity that is continuous with the small-diameter-part-side flange surface partial cavity and the large-diameter-part-side partial cavity. And a sprue and a runner for injecting resin into the cavity.