JPH0745061B2 - Method and device for manufacturing double pipe - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The disclosed technology belongs to the field of manufacturing technology of a double pipe used for piping for transporting crude oil of a corrosive fluid.

<Summary of Summary> Therefore, the invention of this application is such that an outer pipe made of carbon steel or the like and an inner pipe made of stainless steel or the like are relatively overlaid via a ring-shaped clearance, and the inner pipe is tapped from the inside. While cooling with water etc., the outer tube is heated with a predetermined heater etc. to press the inner surface of the outer tube to the outer surface of the inner tube at a predetermined pressure, and then allowed to cool in the atmosphere etc. to reduce the outer tube's inner diameter. The invention relates to a method for producing a double pipe in which the diameter of the pipe is expanded and tightly bound, and an apparatus directly used in the production method, in particular, the outer pipe is set to a predetermined length in a heating furnace, Heat the entire tube evenly with a heater and cool the inner tube, which is relatively layered inside the outer tube, from the inside with tap water, etc., and then apply a tensile force in the axial direction to the heated outer tube to separate them one by one. Alternatively, the outer tube and the inner tube are yielded by reducing the strength due to heating all at once. The invention relates to a method and an apparatus for manufacturing a double pipe in which the outer pipe and the inner pipe are tightly bonded to each other by pressing them and then leaving them to stand.

<Prior Art> As is well known, the pipe has been used not only as a fluid transport means but also as a strength member of a building structure or a mechanical device, and has also been used as a recent information transmission means. Although it is used for various purposes, it is strongly required to have durability in any case, and especially in primitive fluid transportation pipes, etc., various severe conditions such as pressure resistance, heat resistance, wear resistance, touch resistance, etc. There is a strong demand for a function that can handle the conditions, and no single material that satisfies all of these complex conditions has been put to practical use in the material technology at the present time. The obtained double pipe, for example, makes the outer pipe endow with heat resistance and pressure resistance, and the inner pipe endows with touch resistance, wear resistance, etc., and, in addition, both are integrated without causing misalignment. Integrally joined double tube that can function Thus, from the past, for example, the clad method, the shrink fitting method, the hydraulic expansion method, etc. were developed, and recently, many of the applicant's prior inventions, so-called heat expansion methods, etc. according to the invention were developed. Has been put to practical use.

<Problems to be Solved by the Invention> However, the clad method requires a high-pressure and high-heat apparatus, has a disadvantage in that it is costly, and the shrink-fit method has a disadvantage that high accuracy is required. There is a problem that it becomes complicated, and the hydraulic expansion method requires a robust hydraulic device, so the thermal expansion method is in the process of development and pressure handicap and thermal control are complicated and rapid practical use. There is a downside that conversion is not required immediately.

<Purpose of Invention> The purpose of the invention of this application is to withstand pressure based on the above-mentioned prior art,
A technical problem to be solved for the production of double pipes having functions such as anti-corrosion, and a double pipe of a predetermined length is made uniform by a simple device over the entire length, and at a low cost due to high-precision bonding. It is intended to provide an excellent double pipe manufacturing and apparatus which can be obtained by the above-mentioned method and which is useful in the field of utilizing the piping technology in various industries.

<Means and Actions for Solving the Problems> In order to solve the above-mentioned problems, the structure of the invention of the present application, which is based on the above-mentioned object, has the strength by heating the pipe as a whole. The outer tube is set in a predetermined heating furnace and heated on average over the entire length by a heater, etc., while applying the tensile force in the axial direction to reduce the diameter and yield. The inner pipe set relative to the pipe is cooled to a predetermined degree by flowing tap water, etc., where the heated outer pipe is stretched axially to reduce its strength. The inner surface of the outer tube is pressed against the outer surface of the inner tube by partially reducing or yielding the inner tube and the outer tube pressed against the inner tube is cooled through the inner tube to increase its strength. Axial extension stops and thus the total length of the outer tube By obtaining a double tube element pipe that is pressed against the inner tube, opening the element tube from the heating furnace, stopping the heating for the outer tube, stopping the cooling for the inner tube and leaving it in the atmosphere etc. The inner tube has a temperature-expanded diameter and the outer tube has a cooling diameter to reduce the diameter, and technical measures have been taken so as to obtain a predetermined double tube which is entirely tightly connected.

<Example> Next, an example of the invention of this application will be described with reference to the drawings. In general, a steel pipe has a temperature t on the horizontal axis and a strength ρ on the vertical axis, as shown in the characteristic curve in FIG.
It is known that the strength decreases rapidly as the temperature rises. Therefore, when a heating action is applied to a steel pipe and a tensile force is applied in the axial direction, the diameter decreases due to the above-mentioned strength reduction and axial extension. Is obtained.

Therefore, in the invention of this application, by utilizing this characteristic, the outer tube is made to come into contact with the inner tube by reducing the diameter by applying a tensile force in the axial direction through the strength reduction due to the application of heat to the outer tube. It gives a cooling effect to stop the strength reduction,
It is intended to prevent axial expansion and then to leave it in the atmosphere, etc. to ensure that the inner tube expands and the outer tube contracts so that they are tightly connected. Explaining the example with reference to the embodiment shown in FIGS. 4 to 7, as shown in FIG. 4, the carbon steel outer tube 1 and the stainless steel inner tube 2 are relatively overlaid via a predetermined ring-shaped gap, and the heating furnace 3 is used. The inner pipe 2 is accommodated almost entirely and the inner pipe 2 is cooled by tap water or the like, and the outer pipe 1 is heated to a predetermined temperature on average over the entire length by a heater (not shown) in a heating furnace. By applying a tensile force P in the axial direction together with the outer tube 1, as shown in FIG. 8 above, since the strength of the outer tube 1 is decreased by heating, the outer tube 1 easily expands in the axial direction, and partially in order. Alternatively, along the entire length (in the partial order in the embodiment shown in FIG. 5)
The inner diameter of the outer tube 1 abuts on the outer surface of the inner tube 2 by reducing the diameter and yielding, and the abutted portion 5 is cooled by the cooling of the inner tube 2 by heat transfer, and as shown in FIG. When the temperature is lowered, the strength is restored again and the extension in the axial direction is stopped. In part, the portion is extended by applying tension, and the diameter is reduced to yield, and the outer tube 1
The inner surface of the inner tube abuts on the inner surface of the inner tube 2, and this phenomenon occurs over the entire length. As shown in FIG. 6, the inner surface of the outer tube 1 is pressed against the outer surface of the inner tube 2 over the entire length of the double tube. The inner pipe 2 is formed by opening the internal cooling of the inner pipe 2 and stopping the heating of the outer pipe 1 to release the raw pipe 6 from the heating furnace 3 and leaving it in the atmosphere. The diameter of the outer tube 1 is increased by heating, and the outer tube 1 is cooled and reduced in diameter to obtain an average tightness over the entire length.
Can be produced in one shot.

An embodiment that can be implemented in accordance with the above-described principle embodiment will be described with reference to FIGS. 1 to 3. Reference numeral 8 is an apparatus for manufacturing the double pipe 7 which is one of the gist of the invention of this application. , A drum-shaped heating furnace 3 of a prescribed size has a third
As shown in the drawing, seal rings 10 and 11 having heat insulating rings 9 and 9'which are slidably overlapped with each other in the radial direction.
Forms a heat seal 13 that allows axial sliding with respect to the carbon steel outer tube 1 via an elastic rubber 12.

Further, as shown in FIG. 2, the screw ring 15 for the flange-shaped cotter 14 for the outer end portion of the outer tube 1 is provided with a pinion 17 on the outer side of a pulling ring 16 having splines formed on the outer side thereof. 3 is engaged with a pinion 19 of a motor 18 fixedly provided on the outer end of the pulling ring 3 by the normal rotation of the motor 18.
A pulling device 20 is formed so that the pulling action is given to the outer tube 1 outwardly by 16 along the axial direction to give a predetermined extension.

Therefore, in this embodiment, the carbon steel outer tube 1 set in the heating furnace 3 is applied with tensile forces along opposite axial directions at both ends by the tension applying devices 20, 20. ing.

Further, in the heating furnace 3, a heater 21 for uniformly heating the entire length and the entire circumference of the outer tube 1 is provided and connected to a power source 23 via a terminal 22 to form a heating device 24. .

As in the above-described embodiment, the inner tube 2 made of stainless steel is layered inside the outer tube 1 with a predetermined ring-shaped gap therebetween, and the caps 25, 25 at both ends of the inner tube 2 are laminated. The passage 26 for circulating tap water as cooling water is the heat exchanger 2
7. A cooling device 29 is configured by having a circulation pump 28 in series.

In the above-mentioned double pipe manufacturing apparatus 8, the outer pipe 1 made of carbon steel and the inner pipe 2 made of stainless steel are relatively laminated with a predetermined ring-shaped gap therebetween, and the outer pipe 1 is sealed with the seal 13 in the heating furnace 3. Through, connecting the caps 25, 25 of the inner pipe 2 to the circulation passage 26,
When the circulation pump 28 and the heater 21 are activated by the power supply 23, the inner pipe 2 is cooled by the running tap water, and the outer pipe 1
Is entirely heated by the heating device 24 to a predetermined degree, and the motors 18, 18 cause the pinions 19, 19 and the pulling rings 16, 16 to rotate.
The pulling force P of the inner tube 2 is applied in the reverse axial direction via.

Therefore, the strength of the outer tube 1 is lowered by the temperature rise by the heating device 24 as in the case of the principle embodiment shown in FIG. 8 and FIGS. Begins to expand in the direction, and the diameter is reduced accordingly, and it yields from a predetermined portion as in FIG.
The inner surface of the outer tube 1 in this portion is pressed against the outer surface of the inner tube 2 and is immediately subjected to a cooling effect by heat transfer by the inner tube 2 which is being cooled, and as shown in FIG. The axial extension and the diameter reduction are stopped.

Therefore, the portion of the outer pipe 1 that is not in contact with the outer surface of the inner pipe 2 is still expanded in the axial direction due to the axial pulling force P, and at the same time the diameter is reduced and yielded to press the outer surface of the inner pipe 2. Strength recovery and axial extension are stopped, and thereafter, similarly, the outer tube 1 is entirely pressed against the inner tube 2 over time, and axial extension is stopped, whereupon the cooling tap water in the inner tube 2 is stopped. Is removed and the heating of the heating device 24 is stopped, and the double tube raw tube of the outer tube 1 which is in pressure contact with the inner tube 2 is taken out from the heating furnace 3 and left to stand in the air to be naturally cooled. The pipe 1 is further reduced in diameter by heat release and natural cooling, and the inner pipe 2 is increased in diameter by temperature rise due to cooling release, and together, the outer pipe 1 and the inner pipe 2 have a large fitting allowance. It is possible to obtain and tightly bond the double tube 7 in a tightly bound state.

Of course, the embodiment of the invention of this application is not limited to the above-mentioned embodiment. For example, the sizes of the outer tube and the inner tube can be selected as desired as long as the heating furnace allows, and the outer tube and the inner tube can be selected. For pipes, the types are abrasion resistance, touch resistance, pressure resistance,
Various choices such as heat resistance are possible, and the material can be applied not only to metal pipes, but especially to inner pipes such as ceramics pipes and resin pipes. It can also be applied to solid bodies if cooled.

In this way, the outer tube 1 and the inner tube 2 and the process thereof only need to penetrate the heating furnace with the tube body in which the outer tube 1 and the inner tube 2 are relatively laminated.

The embodiment of the invention of this application is not limited to the above-mentioned embodiments, and of course, for example, the production of a double or triple tube having a triple tube or more by adopting a repeated layered mode is intended. It is possible to employ various modes such as the above.

Further, as a design change, in the manufacturing apparatus, the outer tube in which the outer tube of the inner tube is relatively laminated can be set in the heating furnace from the end to the end to manufacture.

Further, the tension applying device for the outer pipe may be of the hydraulic jack type instead of the screw screw type.

<Effects of the Invention> As described above, according to the invention of this application, in the production of a double pipe satisfying complicated and severe conditions such as touch resistance, wear resistance, heat resistance, and pressure resistance, an outer pipe and an inner pipe are manufactured. By inserting a tube body in which the layers are relatively laminated into a heating furnace, cooling the inner tube, and imparting axial tension to the outer tube while the outer tube is heated, the strength of the tube decreases as a result of heating. Along with this, axial expansion occurs, and the diameter decreases and yields, and the inner surface of the outer tube is pressed against the outer surface of the inner tube, where the inner tube cools through heat transfer, and Immediately the strength is restored and the axial extension is stopped, and the portion of the outer tube that is not pressed against the inner tube abuts the outer surface of the inner tube that has been reduced in diameter by tensile in the same manner as above,
Through this process, the outer pipe is pressed into contact with the inner pipe in one shot, whereupon the cooling of the inner pipe is stopped and the heating of the outer pipe is stopped, and the outer pipe is cooled by natural standing in the air. Is cooled and further reduced in diameter, and the inner tube is heated and increased in diameter to obtain a double tube in which the two tubes are securely bonded to each other over the entire length.

Therefore, in terms of the apparatus, it is possible to obtain the tightly bonded double pipe in one step only by using one heating furnace and having the cooling apparatus, the heating apparatus, and the pulling apparatus.

Therefore, there is an effect that the operation is technically easy and the facility is easy, and the cost can be reduced.

In addition, since the double pipe is tightly connected in the one-shot process over the entire length, the overall tightening accuracy is uniformly improved, and thus there is an advantage that the reliability of the product accuracy is high.

Further, by forming a flange joint or the like in advance on both ends of the outer pipe, there is an advantage that it is easy to apply a pressure contact force to the flange joint.

[Brief description of drawings]

1 is a schematic sectional view of a manufacturing apparatus, FIG. 2 is a partially enlarged sectional view of a tension applying device, and FIG. 3 is a partially enlarged sectional view of a sealing device. ,
4 to 7 show the embodiments of the principle embodiment, FIG. 4 is a sectional view showing the installation of the outer tube and the inner tube of the heating furnace in the relative multi-layer tube, and FIG. Sectional view of partial pressure welding of the outer tube to the inner tube, FIG. 6 is a sectional view of the raw tube in which the outer tube is pressure welded to the inner tube in the heating furnace, FIG. 7 is a sectional view of a double tube, and FIG. The figure is a characteristic graph of temperature and tube strength. 1 ... Outer pipe, 2 ... Inner pipe, 7 ... Double pipe, 8 ... Manufacturing device, 3 ...
Heating furnace, 20 ... Tensile force imparting device, 29 ... Cooling device

Continuation of the front page (56) References JP 62-117726 (JP, A) JP 62-212016 (JP, A)

Claims (2)

[Claims] 1. A method for producing a double pipe, wherein an outer pipe and an inner pipe are layered relative to each other, the inner pipe is cooled, the outer pipe is heated to be pressed against the inner pipe, and then left to tightly bond. The outer tube is heated uniformly over the cooled inner tube and heated-
A double pipe characterized by applying a tensile force in the axial direction along the strength curve, yielding and press-contacting the inner pipe as a whole, and then leaving the inner and outer pipes to be tightly connected to each other. Manufacturing method. 2. A double pipe manufacturing apparatus for tightly joining an outer pipe to an inner pipe, wherein a heating furnace for the outer pipe is provided with a tensile force applying device for the outer pipe and a cooling device for the entire inner pipe. A double pipe manufacturing apparatus characterized in that