JPS6351768B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The disclosed technology belongs to the field of pipe expansion technology used in manufacturing double pipes and the like.

<Summary of the gist> This invention relates to a method for increasing the diameter of a pipe by applying a radial expansion force to the inner surface of the inner pipe of the double pipe all around the inner surface of the double pipe using fluid pressure. In particular, a metal coil is spirally wound in the length direction of a spiral tube made of rubber or the like, and both ends of the spiral tube are immovably fixed in position.
Such a spiral tube is attached to the inner surface of the tube, fluid pressure is applied to the inside of the spiral tube, and the length is extended without changing the spiral diameter of the spiral tube to apply tube expansion force to the inner surface of the tube. This invention relates to a method for expanding a pipe.

<Prior art> As is well known, in order to bond the inner and outer pipes of corrosion-resistant double pipes such as oil country tubular goods or to provide backing for butt welding of double pipes, the entire inner pipe or the ends, etc. Technology to expand the pipe around the entire circumference is widely used.

<Problems to be solved by the invention> As shown in FIG.
To tighten the inner and outer tubes, a technology has been developed in which a cap 2 is fitted inside the tube end, a tube expansion liquid is fed from the liquid supply tube 3, and a tube expansion force F is applied from the inside of the inner tube to expand the tube. However, since it has a sealing function in addition to maintaining axial force, the device becomes extremely complex, resulting in high costs and troublesome operation management.

In addition, mechanical pipe expansion using a plug or plug has been used, but it is difficult to uniformly apply pressure all around the circumference.

There are also methods such as shrink fitting, but these have disadvantages in that they require large-scale equipment that covers the entire length of the pipe, and that thermal management control is complicated.

<Object of the Invention> The object of the present invention is to solve the problems of the tube expansion means based on the above-mentioned prior art, and to utilize the elasticity of an elastic tube such as rubber. By utilizing the fact that the double spiral coil is restrained by the double spiral coil and only its ring-shaped circumference can be expanded, the diameter of the first spiral coil can be increased to expand the pipe, which is useful for piping in various industries. It is an object of the present invention to provide an excellent pipe expansion method and device that will benefit the field of technical application.

<Means/effects for solving the problems> In order to solve the above-mentioned problems, the structure of the present invention, which is based on the above-mentioned claims, is to solve the above-mentioned problems by adding metal in the length direction of the spiral tube of the elastic body. A spiral coil made of aluminum is wound and inserted into the tube expansion region of the tube body, and a tube expansion pressure is applied by supplying tube expansion fluid into the spiral tube, so that the cross section of the tube of the component part of the spiral tube becomes the spiral coil. The length of the spiral tube itself is extended through the elasticity of the spiral coil in the length direction of the spiral tube, and a tube expansion force is gradually applied to the inner surface of the tube all around the tube, so that the tube is expanded. This was achieved by taking technical measures to

<Embodiment> Next, an embodiment of the present invention will be described below with reference to the drawings from FIG. 2 onwards.

As shown in Figures 2 and 3, when the metal spiral coil 4 is stretched to 4' with respect to its natural state, the spiral diameter R will substantially change unless the amount of stretching is extremely long. No, but the length L can vary.

Utilizing this, in the principle state shown in FIGS. 4 and 5, a water supply port 6 is provided in the rubber ring tube 5,
Furthermore, when a metal spiral coil 4 is wound around the entire circumference in the length direction and pressurized water is supplied into the ring tube 5 from the natural state shown in FIG. The diameter of the spiral coil 4 cannot be increased because it is constrained by the coil 4, and the circumference of the spiral expands.As mentioned above, pitch expansion in the direction along the ring length of the ring tube 5 of the spiral coil 4 is allowed, so as shown in FIG. As shown, the ring tube 5' increases in diameter.

This invention extracts the force accompanying the diameter increase according to the principle as a pipe expansion force.

In the embodiment shown in FIG. 6, reference numeral 7 is a spiral tube made of rubber, and the cross section of the spiral tube 7 is circular. Both ends of the spiral tube 7 are closed, and near one end there is expanded pressure water. A supply port 6 is provided so that it can be connected to a pump (not shown).

As shown in FIG. 9, a spiral coil 8 having a flat cross section and rounded corners is wound around the entire length of the spiral tube 7 at a predetermined pitch, so that the overall spiral diameter is As shown in FIG. 6, it is loosely fitted into the inner tube 10 inserted into the outer tube 9 of the double tube 1.

Reference numeral 11 denotes a core metal, which is fitted into the inside of the spiral tube 7 and helps maintain the set posture of the spiral tube 7.

In the tube expansion device 12 having the above-described configuration, the core bar 11 is inserted into the spiral tube 7 around which the spiral coil 8 is wound, the front and rear ends of the spiral tube 7 are fixed at appropriate positions to set the pitch, and then the core bar 11 is inserted into the outer tube 9. The inner tube 10 is loosely fitted into the double layered tube 1 in a predetermined manner and set.

Therefore, the supply port 6 is inserted into the spiral tube 7.
When pressurized water is supplied from the pump through the ring, the tube cross section of the spiral tube 7 is restricted by the spiral coil 8 and cannot be increased in diameter, as in the above principle mode, and the pitch of the spiral coil 8 along the length direction of the ring shape is It is elongated by elongation.

However, since both ends of the spiral tube 7 are fixed to the core metal 11, the circumferential length increases so that the diameter of the spiral tube 7 increases, and as a result, the spiral tube 7 becomes the spiral coil 8.
At the same time, the inner tube 10 changes from the state shown in FIG. 7 to the state shown in FIG.
A tube expanding force is applied to the outer tube 9 to fit it into the outer tube 9.

It goes without saying that the embodiments of the present invention are not limited to the above-mentioned embodiments, and can be applied, for example, to backing processing for butt welding of single-layer pipes, and also to the ring-shaped welding shown in FIG. In the present invention, an embodiment in which a plurality of tubes are connected with a pressure water hose and set on a core metal is also included in the scope of embodiments as a modification of the spiral tube.

<Effects of the Invention> As described above, according to the present invention, since the elastic spiral tube made of rubber or the like including a ring shape is wound around a metal spiral coil in its length direction, the tube expansion fluid can be fed. In this state, the cross section of the elastic spiral tube itself does not increase in diameter, but the length of the spiral tube itself in the axial direction increases due to the elongation of the pitch of the spiral coil, and as a result, the spiral cross section diameter of the spiral tube increases when the front and rear ends are restrained. , the excellent effect of increasing the circumferential length and obtaining a large tube expansion force is achieved.

In addition, since the elastic spiral tube is liquid-tightly and airtightly sealed, there is no need for any special sealing device, and it has the advantage that the device is simple, can be manufactured at low cost, and does not require management. liquid,
Since the gas does not come into contact with the pipe body, there is no risk of rusting, etc., and there is no need for post-drying steps, which provides an excellent effect of reducing the number of manufacturing steps.

Further, since the capacity of the spiral tube is small, it has the advantage of requiring less fluid, and if a refrigerant such as liquid carbon dioxide is used, an excellent effect of cooling and expanding the tube can be achieved.

Since the length of the spiral tube can be set freely, there is an excellent effect that straight pipes, curved pipes, and long pipes can be expanded freely.

Furthermore, the spiral pitch and ring pitch can be freely set using the core metal, etc., and there is also the effect that the tube expansion design can be performed flexibly.

[Brief explanation of the drawing]

Fig. 1 is a partial cross-sectional view of pipe expansion based on the conventional technology;
Figures 2 and 3 are perspective views explaining the properties of the spiral coil, Figures 4 and 5 are perspective views explaining the properties of the coil tube, Figures 6 and below are illustrations of one embodiment of the present invention, and Figure 6 is an expanded tube. FIG. 7 is a partial cross-sectional view for explanation, FIG. 7 is a partial cross-sectional view in a set state before tube expansion, FIG. 8 is a partial cross-sectional view after tube expansion, and FIG. 9 is a cross-sectional view of the spiral coil. 1... Pipe, F... Tube expansion force, 5, 5', 7... Spiral tube, 12... Tube expansion device, 6... Supply port, 8,
4,4'...Spiral coil.

Claims (1)

[Claims] 1. A method of expanding a tube by applying a radial expansion force to the inner surface of the tube using fluid pressure, in which a metal coil is spirally wound in the longitudinal direction of an elastic spiral tube and the spiral tube is attached to the inner surface of the tube. A tube expansion method characterized by fixing both ends of the spiral tube in position and applying fluid pressure inside the spiral tube to extend the axial length of the spiral tube itself by the fluid pressure to apply a tube expansion force to the inner surface of the tube and expand the tube.