JP2566622B2 - Manufacturing method of composite pipe having receiving part - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention manufactures a composite pipe having a socket by expanding the diameter of the end of the composite pipe whose inner peripheral surface is covered with a synthetic resin layer. On how to do.

(Prior Art) For example, as a drainage pipe vertically piped in a building, a composite pipe in which an inner peripheral surface of a metal pipe is coated with a synthetic resin layer is used. As shown in Japanese Utility Model Laid-Open No. 59-58279 as a connection between such composite pipes, the end portion of one of the composite pipes is expanded to form a receiving portion, and the receiving portion is formed.
It is known that the insertion opening of the straight tubular end of a composite pipe to be connected via an adhesive layer is inserted and adhesively bonded.

In order to manufacture a composite pipe having such a receiving portion, usually, the end portion of the metal pipe constituting the composite pipe is expanded by bulge forming or punch forming at room temperature, and then directly inserted into the metal pipe. A tubular synthetic resin pipe is fitted with an adhesive, and the end of the synthetic resin pipe fitted in the expanded end of the metal pipe is heated and expanded to expand its diameter. It is manufactured by a method of adhering the expanded end of a synthetic resin tube to the expanded end of a metal tube.

(Problems to be solved by the invention) However, in such a method, the diameter expansion processing of the end portion of the metal pipe, the processing of inserting the straight tubular synthetic resin pipe into the metal pipe and adhering it, and the end of the synthetic resin or the like. Each part needs to be heated to expand the diameter, and workability is extremely poor.

This processing method is adopted because expensive rubber (urethane rubber is used in bulging) because rubber is damaged by heat when bulging is performed by heating the end of the composite pipe. This is because it needs to be replaced frequently.

The present invention solves the above-mentioned conventional problems, and an object thereof is a method for producing a composite pipe having a receiving portion, which is excellent in productivity and in which the synthetic resin layer does not easily peel off from the metal pipe. To provide.

(Means for Solving the Problem) According to the present invention, the synthetic resin layer is stretched by about 10% at the receiving portion formed at the end of the composite pipe, so that the synthetic resin layer is kept at room temperature.
If it has an elongation of about 10%, it can be processed without cracking, and even if the metal tube and the synthetic resin layer are firmly adhered to each other in advance, even if the diameter is expanded at room temperature, it will be combined with the metal tube. If the resin layer is adhered with an adhesive force higher than the desired adhesive force,
Even if the diameter is expanded at room temperature, the metal tube and the synthetic resin layer remain adhered, and the expanded synthetic resin layer does not easily separate from the metal tube over time or due to heat.
It was made based on the findings.

According to the method for producing a composite pipe having a socket of the present invention, the synthetic resin layer is adhered to the inner peripheral surface of the metal pipe with an adhesive layer made of synthetic resin foam so that the adhesive force is 2 kg / cm ² or more. Arranging the end of the composite pipe in an outer mold having an inner peripheral surface of a predetermined shape with a gap from the inner peripheral surface, and fitting an elastic member in the end; The elastic member is compressed in the axial direction at room temperature to expand the elastic member in the radial direction,
The step of expanding the diameter of the composite pipe so that the end portion of the composite pipe is in pressure contact with the inner peripheral surface of the outer die, thereby achieving the above object.

(Example) Hereinafter, the present invention will be described with reference to Examples.

As shown in FIG. 1, a method of manufacturing a composite pipe having a socket according to the present invention includes, for example, a synthetic resin layer 13 made of polyvinyl chloride on the inner peripheral surface of a metal pipe 11 made of steel, for example, urethane foam. The composite tube 10 adhered by the adhesive layer 12 having elasticity as described above is used. The composite tube 10 has an adhesive layer 12
The inner peripheral surface 11 of the metal tube and the synthetic resin layer 13 are adhered to each other so as to have an adhesive strength of ² kg / cm ² or more.

The end portion of the composite pipe 10 is expanded by a bulge processing machine 20 to form a receiving portion.

The bulge processing machine 20 for expanding the diameter of the composite pipe 10 by bulging to form a receiving end at the end of the composite pipe 10 is an external mold capable of being divided into two parts in which the end of the composite pipe 10 is located. Having 21. The outer mold 21 has a through hole 21a at one end surface thereof that is substantially equal to the outer diameter of the composite pipe 10, and the end of the composite pipe 10 extends from the through hole 21a to the outer mold 20.
It is inserted inside. The inner peripheral surface of the outer mold 21 has a shape corresponding to the outer peripheral surface of the receptacle structure to be formed.

A rod 22 is disposed in the outer die 21 so as to be movable in the axial direction along the axis of the composite pipe 10 inserted into the outer die 21 from the through hole 21a. One end of the rod 22 extends to the outside of the outer die 21 from the end surface of the outer die 21 facing the end surface where the through hole 21a is formed, and the end of the rod 22 is a hydraulic cylinder.
It is connected to the piston 23a in 23. Then, when the piston 23a moves in the axial direction of the hydraulic cylinder 23, the rod 22 moves in the axial direction. A disk-shaped pressing portion 24 having an outer diameter substantially equal to the inner diameter of the synthetic resin layer 13 in the composite pipe 10 is attached to the other end of the rod 22.

An elastic member 25 is slidably fitted to the rod 22 between the pressing member 24 and the inner surface of the outer die 21 facing the pressing member 24. The elastic member 25 is made of an elastic body such as urethane rubber, and when the rod 22 is most advanced from the hydraulic cylinder 23, the pressing member 24 does not press the elastic member 25 and the elastic member 25 itself. It is in a stretched state due to the elastic force of. In such a state, the elastic member 25
Has a cylindrical shape with an outer diameter slightly smaller than the inner diameter of the composite pipe 10. When the rod 22 moves in the direction of retracting into the hydraulic cylinder 23, the elastic member 25 is compressed by the pressing member 24 and the inner surface of the composite pipe 10 and expands in the radial direction.

When the bulging machine 20 having such a configuration is used to form the receiving portion at the end of the composite pipe 10, first, the hydraulic cylinder 23
Is driven to keep the rod 22 advanced from the hydraulic cylinder 23. The elastic member is attached to the peripheral surface of the elastic member 25.
A lubricant for reducing friction between 25 and the synthetic resin layer 13 is applied in advance. As such a lubricant, a commonly used lubricant such as silicone, detergent, oil, grease, rubber adhesive or the like is used. In this state, the outer mold 21 is divided into two parts, and the end of the composite pipe 10 is fitted onto the elastic member 25. At this time, the elastic member 25 and the composite pipe 10 have a gap of about 2 mm.

After that, the divided outer mold 21 is integrated and fixed.
The outer die 21 is fixed by a mechanical lock or pressing with a hydraulic cylinder. The composite pipe 10 has only one end located inside the integrated outer mold 21, and the other part is the outer mold 21.
Through the through hole 21a. The inner diameter of the through hole 21a is
The composite pipe 10 is slightly larger than the outer diameter of the composite pipe 10, and the composite pipe 10 is loosely fitted in the through hole 21a.

In this state, the hydraulic cylinder 23 is driven and the rod 22
Is moved in the direction of retreating with respect to the hydraulic cylinder 23. At the same time, pressure is applied to the composite pipe 10 so that the composite pipe 10 is inserted into the outer mold 21. As a result, the pressing member 24 attached to the tip of the rod 22 moves to the end face side of the composite pipe 10 in the outer mold 21, and the elastic member 25 is compressed by the pressing member 24.
The end portion of the composite pipe (10) is radially expanded to press the outer surface of the composite pipe (10) against the inner surface of the outer mold (21). Elastic member 25 outer peripheral surface and composite pipe
When a lubricant is interposed between the inner peripheral surface of the synthetic resin layer 13 of the diaper 10 and the elastic member 25, the elastic member 25 is smoothly compressed and the metal pipe 11
The synthetic resin layer 13 and the synthetic resin layer 13 expand in diameter.

At this time, when pressure is applied to the composite pipe 10 so that the end surface located inside the outer mold 21 is pressed against the inner surface of the outer mold 21,
When the end of the composite pipe 10 is expanded, the diameter of the metal pipe 10 is expanded so that the metal pipe 10 moves into the outer mold 21, so that there is no possibility that the expanded portion will become thin, and the end face There is no possibility that the length of the receiving part is shortened by pulling away from the inner surface of the outer mold 21. After that, the rod 22 is further attached to the hydraulic cylinder.
When the elastic member 25 is further compressed by moving it so as to retreat into the inside 23, the end portion of the composite pipe 10 is further expanded in diameter, and as shown in FIG. It is pressed against the inner surface of the mold 21. As a result, the end portion of the composite pipe 10 is expanded in a predetermined shape to form a receiving portion having a predetermined structure.

When the receiving part of a predetermined shape is formed at the end of the composite pipe 10,
The rod 22 is moved in the direction of advancing from the hydraulic cylinder 23, and the compression of the elastic member 25 by the pressing member 24 is released. Next, the outer die 21 is released from the fixed state to be in the divided state, and the composite pipe 10
Is moved in the axial direction to remove the composite pipe 10 from the elastic member 25. At this time, the hydraulic cylinder 23 may be moved to remove the elastic member 25 from the end of the composite pipe 10.

As a result, the composite pipe 10 having the receiving portion with a predetermined shape is obtained.

As the metal pipe 11, a pipe made of soft iron, copper, aluminum, lead or the like is used, which is not limited to steel.

As the synthetic resin layer 13 that covers the inner peripheral surface of the metal tube 11,
Since it is stretched by about 10% to form the receiving portion, it is preferable to use one having an elongation of 20% or more at room temperature so that no crack is generated when the diameter is expanded. Specifically, it is not limited to polyvinyl chloride (PVC), but polyethylene (P
E), cross-linked polyethylene, polybutene, polypropylene, fluororesin, etc.

The metal tube 11 and the synthetic resin layer 13 are bonded so that the synthetic resin layer 13 does not peel off from the inner peripheral surface of the metal tube 11 when the diameter of the metal tube 11 is expanded at room temperature. It has an adhesive strength of 2 kg / cm ² or more.

Further, since urethane foam, styrene foam, rubber foam, sponge impregnated with adhesive, etc., having elasticity are used as the adhesive layer 12, the end portion of the composite pipe 10 is expanded by the bulging machine 20. When the diameter is reduced, it will be in a compressed state,
After removing the composite pipe 10 from the bulge processing machine 20, the synthetic resin layer 13 contracts and the force of peeling from the inner peripheral surface of the metal pipe 11 can be alleviated, and even when contracted, it elastically expands. Then, it does not follow the synthetic resin pipe and peels off.
Therefore, it is preferable to determine the inner diameter of the outer mold so as to form the receptacle so that the synthetic resin layer 13 has a predetermined inner diameter in a contracted state.

When the bulge processing machine 20 expands the diameter, the pressure applied to the composite pipe 10 in the moving direction of the rod 22 is, for example, a 2 mm thick vinyl chloride coating on the inner peripheral surface of a steel pipe with an inner diameter of 100 mm and a thickness of 3 mm. It takes 5 to 15 tons for the prepared composite pipe. In this case, the total load required to expand the diameter of the end of the composite pipe 10 is 40
~ 50 tons.

When such a pressure is not applied, the composite pipe 10 is fixed to the outer mold 21 when the elastic member 25 is expanded in diameter by compression, and the end face of the composite pipe in the outer mold 21 moves the rod 22. When the end of the composite pipe 10 is expanded, the end face of the composite pipe 10 located in the outer die 21 is in the direction opposite to the moving direction of the rod 22 if the end of the composite pipe 10 is expanded. There is no danger that the expanded part will move and become thinner. Composite pipe 10 and outer mold 21 at this time
For fixing with, the through hole 21a provided in the outer mold 21 is attached to the composite pipe 10
A structure in which the outer peripheral surface is closely adhered, or a structure in which the end opposite to the side where the composite pipe 10 receiving portion is formed is supported by a support such as a metal plate is adopted.

(Effects of the Invention) In the method for manufacturing a composite pipe having a socket of the present invention, synthetic resin foaming is performed in advance so that the inner peripheral surface of the metal pipe and the synthetic resin layer have an adhesive force of ² kg / cm ² or more. Since the end portion of the composite pipe adhered by the adhesive layer composed of the body is constructed by expanding the diameter by the elastic member at room temperature, the workability is remarkably improved and therefore the production efficiency is remarkably improved. Moreover, in the structure of the receiving portion of the obtained composite pipe, there is no risk of cracks in the synthetic resin layer, and there is no risk of the synthetic resin layer peeling from the inner peripheral surface of the metal pipe.

Since the adhesive layer for bonding the metal pipe and the synthetic resin has elasticity, the synthetic resin layer elastically follows the synthetic resin layer even if the diameter of the end of the composite pipe is expanded and the diameter of the synthetic resin layer is reduced. The peeling from the inner peripheral surface of the metal pipe can be reliably prevented.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an implementation state of a method for manufacturing a composite pipe having a socket according to the present invention, and FIG. 2 is an operation explanatory view thereof. 10 …… Composite pipe, 11 …… Metal pipe, 12 …… Adhesive layer, 13 …… Synthetic resin layer, 20 …… Bulge molding machine, 21 …… Outer mold, 22 …… Rod, 23 …… Hydraulic cylinder, 24 …… Pressing member, 25 …… Elastic member.

Claims (1)

(57) [Claims] 1. A pipe end of a composite pipe adhered to an inner peripheral surface of a metal pipe with an elastic adhesive layer made of synthetic resin foam so that the synthetic resin layer has an adhesive force of ² kg / cm ² or more, A step of placing an elastic member in the outer mold having an inner peripheral surface having a shape with a gap from the inner peripheral surface, and fitting the elastic member in the end portion in an axial direction at room temperature. And a step of expanding the elastic member in the radial direction so that the end portion of the composite pipe is in pressure contact with the inner peripheral surface of the outer die, and a method for producing a composite pipe having a receiving portion.