JPS6128418B2 - - Google Patents

Description

[Detailed Description of the Invention] <Industrial Field of Application> The disclosed technology belongs to the technical field of manufacturing fastened double pipes such as oil country tubular goods through hydraulic pipe expansion.

<Summary of the gist> Therefore, the present invention provides both ends of an outer tube made of carbon steel, etc.
Alternatively, with one end free, one end of the relatively overlapping inner tubes is clamped with a fixed seal head fixed to the base and a corresponding seal jaw, and a movable seal head is provided on the inner surface of the other end. This invention relates to a fastened double pipe manufacturing device which is slidable relative to the pipe and in which a fixed seal head is provided with a pipe expansion hydraulic pressure passage communicating with a pipe expansion chamber formed on the inside of the inner pipe. The seal head is provided with a seal jaw for fixing the proximal end of the inner tube, and is also provided with an integrally extending rod, at the tip of which integrally has a movable seal head against the inner surface of the inner tube that retracts in the axial direction when the tube is expanded. This invention relates to a fastened double-pipe manufacturing apparatus that is configured to

<Prior art> As is well known, piping is used not only for fluid transportation, but also for cable routing guides, gas transportation such as documents, etc.
Widely used in all industries, including speaking tubes.

However, for piping in corrosive fluids and atmospheres, especially piping under conditions involving high heat and pressure, single-layer pipes have sufficient strength in addition to pressure resistance, corrosion resistance, and heat resistance. At the current stage of material development, it is almost impossible to create a tube that satisfies all of these conditions to the greatest extent possible, and to overcome this, double tubes such as so-called corrosion-resistant double tubes are used.

Among these double pipes, pipe bodies made of metallurgically bonded materials such as clad steel have various difficulties in manufacturing, cost, and performance, even though they have been technologically developed for a long time. Recently, non-metallurgically bonded double pipes of the type shown by the so-called heat expansion method, etc., disclosed in many prior inventions etc. based on the applicant's development research, have been adopted. For example, a tube body is used in which the outer tube is made of carbon steel and the inner tube that is tightly integrated with the outer tube is made of stainless steel.

Such corrosion-resistant double pipes can only be produced in a set unit length at the time of manufacture due to restrictions on manufacturing equipment or transport restrictions until on-site installation.

Therefore, there are so-called shrink-fitting methods and explosive contact methods to make unit-length corrosion-resistant double pipes, but the hydraulic pipe expansion method shown in many of the applicant's inventions does not require much equipment or equipment. There are advantages in terms of manufacturing methods.

Although the hydraulic pipe expansion method is superior in that tighter margins can be reliably obtained, various problems have been pointed out in the past in terms of material yield and product accuracy.

To explain these problems one by one, the basic problem is pointed out in Fig. 1. For example, if both ends of an outer tube 1 made of carbon steel are left free and an inner tube 2 made of stainless steel is layered relative to each other, then both ends of one of the flares 4 is fixed to a tapered cone 5 serving as a fixed seal head, and is clamped and sealed by a corresponding seal jaw 6; The flare 4' at the end is also brought into contact with the cone 5' of the fixed seal head, and the corresponding seal jaw 6' is clamped and sealed, and a predetermined line is connected from the enlarged hydraulic pressure passage 7 provided in the cone 5 of one fixed seal head. The tube expansion liquid 8 is supplied to the inside of the inner tube 2 and applied to the tube expansion liquid pressure P to increase the diameter of the inner tube 2 and expand it, which is then plastically deformed and integrated with the outer tube 1 to form a tight connection. I was trying to do that.

However, in such a means, since the fixed seal heads 5, 5' at both left and right ends are fixed, the inevitable axial contraction accompanying the diameter increase of the inner tube 2 is restrained, and the axial stress is reduced. will be built-in as tensile residual stress, and this will occur in the inner pipe 2.
There was a problem that this could hinder the diameter increase in the circumferential direction of the product, and also caused stress corrosion cracking of the corrosion-resistant double pipe of the product.

To deal with this, as shown in Figure 2, both ends of the outer tube 1 are sufficiently free, and the length of the inner tube 2 is relatively stretched in the axial direction to absorb the amount of shrinkage so that there is no residual stress. By installing one of the cones 5' as a movable seal head, the tube expansion liquid 8 is supplied into the inner tube 2 from the tube expansion hydraulic pressure passage 7 of the cone 5 of one fixed seal head, and the tube expansion hydraulic pressure P is increased.
When this is applied, the inner tube 2 increases in diameter as described above, comes into contact with the outer tube 1, deforms plastically, and freely contracts in the axial direction to prevent the formation of tensile residual stress in the inner tube 2. Buckling of the end of the tube 2 is now avoided.

However, it is extremely difficult to select materials, and even if it is possible to obtain an appropriate radial clearance 3 between the outer tube 1 and inner tube 2 in the initial set, the length cannot be obtained as designed. , as shown in Fig. 2, in the process where the inner tube 2 comes into contact with the outer tube 1 and plastically deforms to increase its diameter, the end of the inner tube 2 does not match that of the outer tube 1, and it becomes long. In this case, as shown by the dotted line,
The end portion bulged out in the radial direction by the length of 2'' with respect to the outer tube 1, and it had the disadvantage that it could not withstand the internal pressure P, resulting in rupture.

As a result, there is a problem that the internal pressure decreases and a predetermined fastened double pipe cannot be obtained.

<Problems to be Solved by the Invention> Therefore, as shown in Fig. 3, the length of the inner tube is increased by adding the amount of axial contraction l to the left and right ends of the inner tube to its effective length L, and sealing pads are installed at both ends. 9,9'
The movable seal heads 10, 10' which can be slid relative to each other are set with the outer tubes 10 and 10' being exteriorized, and the outer tube 1 is set between them so that both ends are free so that they overlap each other, and the expansion liquid of one movable seal head 10 is set. When tube expansion liquid 8 is supplied from pressure passage 7 and tube expansion liquid pressure P is applied, inner tube 2 increases in diameter, integrates with outer tube 1 through gap 3 between the inner and outer tubes, and undergoes plastic deformation to integrate both tubes into one body. During this period, the inner tube 2 contracts in the axial direction with respect to the two movable seal heads 10, 10' and absorbs the amount of contraction l, so that a corrosion-resistant double tube is obtained.

Therefore, since both ends of the outer tube 1 are in contact with the two movable seal heads 10 and 10', both ends of the inner tube 2 do not bulge out relative to the outer tube 1.
Therefore, neither rupture nor buckling occurs at both ends of the outer tube 1.

However, as shown in the figure, this embodiment naturally has a problem in that a pressing force P in the axial direction acts on both movable seal heads 10 and 10', so a presser reaction force P' is required in response to this. .

In addition, in the tube expansion operation using the actual device, it is unclear whether axial contraction of 1 will occur at either or both the left and right ends of the inner tube 2, and therefore it is necessary to take the amount of contraction 1 at both ends of the inner tube 2. This has the disadvantage of poor material yield and high cost.

Therefore, as shown in FIG. 4, a flare 4 is formed at one end of the inner tube 2 as described above, and the flare 4 is brought into contact with the cone 5 serving as a fixed seal head, and the cone 5 is clamped and fixed by a corresponding seal jaw 6 for sealing. ,
The movable seal head 10' can be slid relative to the other end of the inner tube 2 via a packing 9' as shown in FIG. It is set between the seal jaw 6 and the movable seal head 10' with both ends in contact with each other, and in this state, the tube expansion liquid 8 is supplied from the tube expansion hydraulic pressure passage 7 provided in the cone 5 serving as the fixed seal head to hydraulically expand the tube. The inner tube 2 increases in diameter and comes into contact with the outer tube 1, undergoes plastic deformation, and the accompanying axial contraction occurs through relative sliding with the movable seal head 10'.

Therefore, in this embodiment, one end of the inner tube 2 is fixed to the cone 5 as a fixed seal head by axially contracting the end of the inner tube 2 by l only with respect to the movable seal head 10' at one end. death,
It is only necessary to form the axial contraction amount l in advance for the movable seal head 10', and the above-mentioned swelling and rupture of the inner tube 2 and buckling of the end of the outer tube 1 do not occur, and the tightening is prevented. The double pipe itself has the advantage of being able to be used as designed.

However, in this embodiment, the cone 5 as a fixed seal head and the movable seal head 10'
A connecting rod or the like such as a tie rod 11 that supports the reaction force P' against the pipe expansion hydraulic pressure P is required between the pipe and the pipe, which has the disadvantage that the device becomes large-scale and the management and control are complicated.

In addition, the applicant's earlier patent application, JP-A-57-
The invention disclosed in No. 177838 discloses a double pipe manufacturing device, in which a seal head that slides relatively inside an inner pipe layered relative to an outer pipe is connected to a rod. When tightening, the seal head and rod are moved back relative to the inner tube by a heating device and a cooling device installed outside the outer tube of the seal head. Therefore, both ends of the inner tube are temporarily fixed, and as long as Although not shown in detail, the entire rear end is clamped to prevent the inner tube from contracting when the inner tube is expanded relative to the outer tube, and as a result, as mentioned earlier, tensile stress remains in the inner tube. This problem was unavoidable.

As a result of research and consideration of the prior invention, the inventor has developed the present invention as a new device for producing a fastened double pipe.

<Objective of the Invention> The object of the present invention is to solve the problems of the manufacturing apparatus for fastened double pipes, etc. based on the above-mentioned prior art, and to sufficiently allow the shrinkage of the inner pipe in the axial direction.
To provide an excellent bonded double pipe manufacturing device which prevents bulging and bursting, as well as buckling of the end portion 1 of the outer tube, and also simplifies the structure of the entire device, benefiting piping application fields in various industries. This is what I am trying to do.

<Means/actions for solving the problems> In order to solve the above-mentioned problems, the structure of the present invention, which is summarized in the above-mentioned claims, is such that one end of the inner pipe in which the outer pipe is layered relative to the outer pipe is A fixed seal head and a sealing jaw integrated with the fixed seal head clamp and fix the seal, and a movable seal head that can slide against the other end side of the inner tube is attached in a liquid-tight manner to the tip of a rod that extends integrally from the fixed seal head at the proximal end of the inner tube. The length of the axial contraction amount of the inner tube is set at the other end of the inner tube, and when the tube expansion liquid is supplied from the tube expansion hydraulic pressure passage of the fixed seal head, the rod and the inner tube are The tube expansion chamber is immediately filled with tube expansion liquid, and the inner tube increases in diameter, becoming integrated with the outer tube and plastically deforming. Technical measures have been taken to ensure that a bonded double tube can be obtained without shrinking, causing the inner tube to bulge and rupture, or buckling the outer tube end.

<Embodiment - Configuration> Next, an embodiment of the present invention will be described based on FIGS. 5 and 6 as follows.

Note that the same parts as in FIGS. 1 to 4 will be described using the same reference numerals.

In the embodiment shown in FIG. 5, reference numeral 1 denotes an outer tube made of carbon steel, and an inner tube 2 made of stainless steel that overlaps the outer tube with a gap 3 interposed therebetween has a tapered flare that opens outward on the proximal end side. 4.

On the other hand, a rod 12 of a predetermined diameter integrally formed with an inwardly tapered cone 5 has a seal 9 at its tip, and a movable seal head 13 having a short cylindrical shape.
are integrally formed.

Then, the inner tube 2 is inserted through the flare 4, the flare 4 is brought into contact with the cone 5 serving as a fixed seal head, and the seal tube 6 corresponding to the cone 5 is inserted.
This allows the flare 4 to be sealed and fixed between the cone 5 and the seal jaw 6 in a fluid-tight manner.

Therefore, in this state, the flare 4 on the base end side of the inner tube 2 is fixed to the cone 5, and the tube expansion chamber 14 is formed outside the rod 12.

The inner tube 2 has a movable seal head 1 at its rear end.
The total length of the inner tube 3 is formed in advance so that the rear portion of the inner tube 2 has a length equal to the axial contraction amount 1 when the inner tube 2 is expanded.

Further, the proximal end side of the outer tube 1, which surrounds the outside of the inner tube 2 and is relatively layered, is brought into contact with the seal jaw 6, and the rear end is left in a free state, so that the rear end of the outer tube 1 is connected to the inner and outer tubes. The end of the movable seal head 13 is formed to have an overhanging length so that the inner tube 2 can be integrated with the inner tube 2 and not bulge or burst when the inner tube 2 is expanded.

Further, in the embodiment shown in FIG. 6, the clamp at one end of the inner tube 2 is clamped by a short circular portion parallel to the axial direction of the cone 5' and the seal jaw 6'.

In the two embodiments described above, the cone 5 serving as the fixed seal head is provided with a tube expansion hydraulic pressure passage 7 which communicates with the inside of the rod 12, and furthermore, a tube expansion chamber between the rod 12 and the inner tube 2. 14.

<Embodiment - Effect> When the pipe expanding liquid 8 at a predetermined temperature, for example, normal temperature, is supplied under pressure from the pipe expanding hydraulic pressure passage 7 of the cone 5, 5' as a fixed seal head in the state set as described above, The inner tube 2 is supplied from the tube expansion hydraulic pressure passage 7 to the tube expansion chamber 14 between the rod 12 and the inner tube 2, and the inner tube 2 increases in diameter, expands, and is integrated with the outer tube 1 with no gap 3, and is plastically deformed. The diameter of both tubes increases.

During this period, the inner tube 2 contracts in the axial direction as described above, but its proximal end is compressed by the cones 5, 5' and
Since it is restrained by the seal jaws 6 and 6', its free outer end side is attached to the rod 1 relative to the cone 5.
It slides relative to the movable seal head 13 via 2 and is drawn inward, absorbing the amount of contraction l and being drawn in.

In such a tube expansion process, the inner tube 2 undergoes a predetermined lengthwise contraction to achieve a predetermined plastic diameter increase, and the outer tube 1 is tightened without buckling to form a predetermined tightening doublet. A tube is obtained.

By the way, in recent years, the thermal expansion method has been developed and used in the production of bonded double pipes, as described above. The inner tube 2 can be kept cool.

Furthermore, since the rod 12 is inserted into the interior of the inner tube 2, the volume inside the inner tube 2 is reduced by that amount, and the supply of cooling liquid and tube expansion liquid 8 can be carried out quickly.

The tube expansion pressure P' applied to the movable seal head 13 during the tube expansion process can be directly supported by the cone 5 by the rod 12.

Therefore, no tensile residual stress is formed in the inner tube 2 of the manufactured fastened double tube, there is no swelling or rupture at the end, and the outer tube 1 is in good condition with no buckling at the end. You can get a good product.

In the embodiment shown in FIG. 6, the opposing surfaces of the clamp 5' as a fixed seal head and the corresponding seal jaw 6' are parallel to each other in the axial direction, making it easy to set the inner tube 2. This is an embodiment that only requires the provision of a seal 9'' for the inside of the base, and there is virtually no difference in its operation and effect from the embodiment described above in FIG. 5.

It goes without saying that the embodiments of the present invention are not limited to the above-mentioned embodiments. For example, instead of the movable seal head for the end of the inner tube in the above-mentioned embodiments being a movable seal head facing inside of the inner tube, Various embodiments such as a movable seal head facing the outside can be adopted.

<Effects of the Invention> As described above, according to the present invention, basically in an apparatus for manufacturing a bonded corrosion-resistant double pipe such as an oil country tubular goods, no tensile residual stress is formed in the axial direction of the inner pipe that relatively overlaps the outer pipe. Also, there is no outward bulge rupture at the end of the outer tube, no buckling at the end of the outer tube, and furthermore, it supports the axial reaction force during the tube expansion process. There is no need for special equipment to process the product, the yield of materials for the product is high, and it can be manufactured at low cost.
It has a simple structure, does not require much maintenance and inspection work, and has excellent durability.

Thus, the movable seal head for the other end of the inner tube is fixed to the fixed seal head for one end of the inner tube via a rod integrated with the fixed seal head so as to slidably seal the other end of the inner tube in a liquid-tight manner. As described above, this allows sufficient axial contraction of the free end of the other end of the inner tube during the tube expansion process, and reduces the amount of axial contraction of the free end of the outer tube that overlaps the inner tube. The excellent effect of being able to set accurately only at the ends is achieved.

Therefore, this has the effect of preventing the inner tube from bulging outward and bursting, and since one end of the outer tube can be left in a free state, the end of the outer tube is free from buckling. An excellent effect is achieved in that no problems such as the like occur.

[Brief explanation of the drawing]

1 to 4 are schematic cross-sectional views of the operation of a fastened double pipe manufacturing apparatus based on the prior art, and FIGS. 5 and 6 are illustrations of an embodiment of the present invention. FIG. 6 is a schematic sectional view of another embodiment equivalent to FIG. 5. 1... Outer pipe, 2... Inner pipe, 5, 5'... Fixed seal head, 13... Movable seal head, 7...
Pipe expansion hydraulic pressure passage, 14...tube expansion chamber, 12...rod, 6, 6'...seal jaw.

Claims (1)

[Claims] 1. A fixed seal head for one end of an inner tube and a movable seal head for the other end, which is disposed inside an outer tube relatively overlapping with at least one end in a free state, and an expanded pipe hydraulic passage is provided in the fixed seal head and the inner tube is In a fastened double pipe manufacturing device that communicates with a tube expansion chamber formed on the inside of the pipe, the fixed seal head has a seal jaw that fixes one end of the inner pipe, and furthermore, a rod integrated with the fixed seal head is attached to the inner pipe. A movable seal head is integrally fixed to the tip of the inner tube, and the other end of the inner tube is arranged so as to be retractable in the axial direction so as to be slidable relative to the inner tube. Fastening double pipe manufacturing equipment.