JPH0337073B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The disclosed technology belongs to the technical field of wear-resistant double pipes in which an outer pipe and a wear-resistant inner pipe made of ceramic or the like are tightly connected.

<Summary of the gist> The invention of this application, in order to improve the abrasion resistance of piping used for slurry transportation, pneumatic transportation of granules, etc., involves relatively overlapping an outer tube and a wear-resistant inner tube. A double-tube blank tube is used, and the circumferential annular heating means such as high-frequency induction heating and the cooling means such as water in the front and rear stages are moved in the axial direction relative to each other to perform circumferential annular heating following the cooling of the previous stage. The invention also relates to a wear-resistant double tube in which the inner tube is tightened by the outer tube after cooling at a later stage, and a method for manufacturing the same, and in particular, the invention relates to the outer tube of the double tube blank tube. A large number of short cylindrical segments of a wear-resistant material such as ceramics are lined adjacent to each other, and when the outer tube is heated in an annular manner and the stages before and after it are cooled, thermal expansion of the heated portion is performed. After cooling, the outer tube follows the inner tube by continuously applying an operation in the axial direction to make the diameter of the heated portion smaller than the initial diameter by annular heating and cooling whose diameter is constrained by the surrounding low-temperature portion. This invention relates to a wear-resistant inner-lined double pipe that can be tightened to obtain a strong fitting margin, and a method for manufacturing the same.

<Prior art> As is well known, piping is widely used for transporting fluids in various industrial fields. A problem with slurry transport pipes for transporting slurry or pneumatic transport pipes for granular materials such as dust and silica sand is that the inner surface of the pipes is easily worn out.

This kind of piping usually uses inexpensive steel pipes such as gas pipes, and when they wear out, they are replaced with new pipes or welded patches to the worn parts to cope with this problem.

<Problems to be Solved by the Invention> However, in piping for applications where wear resistance is particularly required, pipes made of materials with excellent wear resistance such as high chromium cast iron may be used.

By the way, the wear resistance of steel materials generally has a good correlation with hardness, and materials with excellent wear resistance are uniformly extremely hard.

For example, it is often used as a wear-resistant material.
27Cr cast iron has a Shore hardness of 81 or higher.

However, on the other hand, as the hardness increases, the toughness of the steel material tends to decrease, and pipes made of wear-resistant materials such as the above-mentioned high chromium cast iron have the disadvantage of being susceptible to breakage when subjected to impact force.

In addition, since high-hardness wear-resistant materials have extremely poor weldability and workability, firstly, it is impossible to attach flanges by welding to connect unit pipes together, and secondly, Even when the flange is integrally formed, finishing work and drilling holes for bolts are difficult, and thirdly, repair welding is difficult.

In addition, it also has the disadvantage of high manufacturing costs.

For this reason, so-called clad steel pipes, which are steel pipes lined with a wear-resistant material, have come into use.

This type of clad steel pipe is usually made by centrifugal casting or overlay welding, and the lining is metallurgically joined to the pipe body.

Since the inner surface of the clad steel pipe is covered with a wear-resistant material, it has much better wear resistance than ordinary single-layer steel pipes made of materials that do not take wear resistance into consideration. ing.

Furthermore, since the tube itself does not need to be provided with wear-resistant material, it is possible to use a material that has sufficient toughness and good weldability.

Therefore, unlike a pipe made only of wear-resistant material, it has sufficient impact resistance, and it is also possible to form a connecting flange separately and attach it by welding.

However, in clad steel pipes, tensile stress remains in the inner lining regardless of the manufacturing method, so there is an inconvenience that cracks are likely to occur during operation.

Another drawback is that once a crack occurs, the crack can easily propagate to the tube body, resulting in a through crack, since the inner tube is metallurgically joined to the outer tube.

Therefore, we developed a double-layered tube consisting of an outer tube with sufficient toughness for practical use and an inner tube with excellent wear resistance. Therefore, it is desired to develop a self-stressing double pipe in which the inner pipe is placed in a compressive stress state.

This is because such self-consolidated double pipes have the same advantages as clad steel pipes, and also eliminate the above-mentioned drawbacks of clad steel pipes.

By the way, the conventional self-tightening double-pipe manufacturing techniques include the first, the shrink-fitting method, the second, the tube expansion method, and the third, the so-called heat expansion method. As for manufacturing methods, each of these methods has disadvantages.

First, the first method requires strict machining accuracy for the inner diameter of the outer tube and the outer diameter of the inner tube, but in the case of a double inner tube with wear resistance, the inner tube is made of a wear resistant material that is difficult to work with. , it is very difficult to perform the required processing.

In addition, this method generally makes it extremely difficult to fit long tubes.

In addition, in both the second and third methods, the inner tube is expanded plastically, but in this case, the strength (yield point) of the inner tube is extremely high in the case of double-walled pipes that are corrosion-resistant. Since the inner tube is a little thicker than this, extremely high tube expansion pressure is required, which is not practical.

In particular, in the second method, the strength (yield point) of the inner tube
In the case of a double-walled pipe where the strength (yield point) of the outer pipe is higher than that of the double-walled pipe, even if the inner pipe is expanded plastically, a gap will be created between the inner and outer pipes due to the difference in elastic return.

In order to deal with this problem, in the invention of Japanese Patent Application No. 60-122663 (Japanese Unexamined Patent Publication No. 61-283416), which is an earlier invention of the applicant, an outer tube and an inner tube are relatively layered to form a blank tube, By providing an annular heating means on the outside of the outer tube, further providing an annular cooling means such as a water shower before and after the outer tube, and moving these means and the base tube relative to each other in the axial direction, the annular heating means The diameter of the outer tube is expanded, the expansion diameter is constrained by cooling means before and after the expansion, the outer tube is yielded, a large diameter reduction effect is applied by cooling contraction, and the outer tube is tightened against the inner tube, thereby automatically We have developed a new double-pipe manufacturing technology that skillfully obtains tight double-pipe pipes.

On the other hand, recent material development research has led to the emergence of new materials with high strength and excellent wear resistance, such as ceramics, which have become possible for mass production. Paste with adhesive, for example, Utility Model Publication No. 41-21247
Techniques such as those disclosed in Japanese Utility Model Application Publication No. 59-94694 have been developed.

However, with this type of technology, the ceramic pieces inside the pipes used are not firmly bonded, resulting in peeling during operation. However, it also has the disadvantage of being extremely difficult both technically and cost-wise.

As described above, although there is a strong need for a wear-resistant double pipe, the prior art has not been able to provide a wear-resistant double pipe that satisfies the conditions as a practical matter.

<Objective of the Invention> The object of the invention of this application is to solve the technical problem of manufacturing a wear-resistant double tube based on the above-mentioned prior art, and to solve the problem of manufacturing a wear-resistant double tube based on the above-mentioned prior art. Alternatively, a large number of arch-shaped pieces are placed adjacent to each other to form an inner tube, and these pieces are inserted relatively loosely into the outer tube to perform circumferential annular heating and cooling at the front and rear of the outer tube at the same time. Concurrently and continuously in the axial direction, for example, by applying a heating and cooling effect while moving relative to each other in the axial direction, the diameter of the outer tube is reduced and the inner tube is tightened by the outer tube. It is an object of the present invention to provide an excellent wear-resistant lined double pipe that is useful in the field of piping technology and a method for manufacturing the same.

<Means/effects for solving the problem> In order to solve the above-mentioned problem, the structure of the invention of this application, which is summarized in the above-mentioned claims, includes a large number of segments of the outer tube and the wear-resistant material, Inner tubes made of arch-shaped pieces are relatively layered to form a blank tube, and when reducing the diameter of the outer tube of the blank tube, annular heating is applied to the outer tube and a circumferential annular heating means is used. The cooling means and the raw pipe are moved relative to each other in the axial direction over time, and at this time, by providing the cooling means in front and behind the annular heating means, the heated portion is The presser bending moment in the radial direction toward the center is applied continuously in the longitudinal direction at the front and rear of the
The expanding diameter of the heated part of the outer pipe is constrained by the surrounding cooling part to yield, and then the inner pipe is tightened with the outer pipe so that the diameter is reduced from the initial diameter by cooling contraction, and each piece of wear-resistant material is A technical measure has been taken to bring them into mechanically strong contact with each other and to firmly fix them to the outer tube.

<Example> Next, an example of the invention of this application will be described below based on the drawings.

The illustrated embodiment is a wear-resistant lined double pipe such as a slurry transport pipe having an inner pipe made of ceramics, and its manufacturing mode.
The inner tube 2 is made of a material with high toughness such as low carbon steel, and the inner tube 2 is made of, for example, short cylindrical segment-shaped pieces 2', 2', made of alumina ceramics, which have high wear resistance and high hardness. The outer tubes 1 are placed adjacent to each other in the axial direction to a set length using
and the inner tube 2 are appropriately inserted relatively loosely to form a double-pipe blank tube 3.

First, an embodiment of the method for manufacturing a wear-resistant lined double pipe according to the invention of this application will be explained with reference to FIGS. 3 to 6.
It is set to move at a predetermined speed in the axial direction as shown by the arrow in the figure, and furthermore, as shown in FIG. Hereinafter, a heating device (hereinafter abbreviated as a heating device) is set, and cooling devices 5, 5 of an annular shower device, such as tap water, for example, are set in front and back in the axial direction close to the heating device 4 at a predetermined distance apart.
unit, and by moving the double tube blank tube 3 in the direction of the arrow, the heating device 4, the cooling device 5,
One unit of 5 is made to move relative to the double tube material tube 3.

Therefore, when the double tube blank tube 3 is relatively moved in the axial direction at a predetermined speed, the heating device 4 applies an expansion effect due to heating to the cooling of the outer tube 1 by the cooling devices 5 before and after it. , in this process,
As schematically shown in Fig. 3, if both ends of the heating part are free ends with respect to the cooling part, the diameter will freely expand and protrude in the circumferential direction as shown in Fig. 3, but in reality, The expansion diameter of the heated portion is restricted by the cooling portion at both ends thereof, and as a result, a ring-shaped curved plastically deformed portion is formed. This process is carried out independently of the ring-shaped piece 2' of each ceramic segment that constitutes the inner tube 2.

Then, as the double tube blank tube 3 moves relatively in the direction of the arrow, the portion of the outer tube 1 that is heated and plastically deformed by the heating device 4 passes through the heated portion and is cooled by the cooling means. As shown in Figure 6,
The outer tube 1 contracts and conversely becomes smaller in diameter to a greater extent than its initial diameter, and a large fitting margin is obtained, and the outer tube 1 exerts a hoop tightening action on the inner tube 2 (the ring-shaped piece 2' of each segment), and both tubes 1 , 2 will be tied together.

Since the action of this one unit acts on all the circumferential parts of the outer tube 1, the double tube element tube 3
By continuously moving the outer tube 1 in the axial direction,
The diameter of all parts of the inner tube 2 is reduced, and a restrained fit is created over the entire length of the inner tube 2 over the entire length of the double tube element tube 3, resulting in a self-contained double tube as shown in Figure 1. A wear-resistant double-lined tube 6 of the tube is formed.

The above-mentioned tightening process is performed regardless of the wall thickness of the ring-shaped piece 2' of each ceramic segment of the inner tube 2, and regardless of the axial length, Furthermore, since the process is performed with almost no relation to the accuracy of the joining surfaces of the outer tube 1 and the inner tube 2, the wall thickness of the inner tube 2 (each segment piece 2') is large, and , wear-resistant lined double pipe 6 which is a long pipe
It is extremely effective for the production of

In the above embodiment, the inner tube 2 made of ceramics has a ring-shaped piece 2' having a large number of segments arranged in the axial direction.
2'... are placed in an adjacent state, but the second
As shown in the figure, an embodiment in which a large number of so-called Yatsuhashi-shaped pieces 2'', 2'', which are arch-shaped in the circumferential direction, are adjacent to each other in the circumferential direction and the axial direction is also possible. The inner tube 2 having a circular cross section can be configured to be mechanically mutually restrained by the hoop tightening action of the inner tube 2.

Therefore, the compressive stress in the circumferential direction and the axial direction of the inner tube 2 acts strongly, and the mutual sealing action of each piece 2', 2', . . . works strongly, so that no leakage of the working fluid occurs.

Therefore, in the above embodiment, when one unit is moved relative to the double tube blank tube 3, if the double tube blank tube 3 is a long tube as described above, one pass by one unit is not enough for the experiment. According to, the diameter of outer tube 1 is
If the diameter is 100φ and the wall thickness is 4t, the diameter will be reduced by about 0.5mm in one pass.

It goes without saying that the embodiments of the invention of this application are not limited to the above-mentioned embodiments, and the inner tube may be made of not only ceramics but also a double-walled tube with an inner tube lined with a special Teflon-treated wear-resistant material. Production method,
Various embodiments can be adopted, such as a double pipe using a corrosion-resistant material for the inner pipe and a method for manufacturing the same.

Moreover, it is applicable not only to straight pipes but also to curved pipes such as bent pipes.

Note that the invention of this application differs from the conventional circumferential diameter increasing/reducing means by means of applying linear heating or cooling means in the direction of movement. The diameter is reduced by being restrained by the adjacent cooling part, and the diameter of the heating part is reduced after cooling. For example, when manufacturing a double pipe, the outer pipe is tightly connected to the inner pipe. The mechanism is completely different.

<Effects of the Invention> As described above, according to the invention of this application, basically in a wear-resistant lined double pipe such as a slurry transport pipe, the wear-resistant lined pipe fastened to the inner surface of the outer pipe has a short tubular shape. The lined tubes made of ceramics, etc., which are difficult to manufacture in long tubes because they are mechanically connected to each other by a large number of segments and arch-shaped pieces and come into contact with the outer tube, have become quite long. In addition, an excellent effect is achieved in that it is possible to form the inner and outer tubes in a relatively overlapping manner, and the initial stacking of relatively overlapping inner and outer tubes can be performed easily.

In addition, since each piece is fastened together by hoop tightening of the outer tube, it is mechanically stable and has the excellent effect that peeling does not occur during operation.

Furthermore, the corrosion resistance of each piece of the inner tube, which is subjected to compressive stress due to the hoop tightening of the outer tube, is improved, and the sealing performance between each piece is improved, preventing leakage of working fluid and improving durability. effect is produced.

Therefore, when manufacturing wear-resistant double-lined pipes, etc.,
The diameter of the outer tube can be reduced, and there is no risk of gaps occurring due to the difference in elastic return based on the difference in yield points between the outer tube and the inner tube, which is the case with hydraulic expansion methods, etc., and it can be used as a self-contained double tube. This method has the excellent effect of obtaining piping with extremely high precision, and also does not require the enormous pressure required for pipe expansion, resulting in low power costs during production, and has the effect of being able to be manufactured at low cost. .

Also, unlike conventional shrink fitting methods, the accuracy of the joint surface between the outer tube and inner tube is not required to be as great.
Therefore, as mentioned above, there is an effect that long tubes and the like can be manufactured freely.

Furthermore, even if the inner tube is made of highly wear-resistant materials such as ceramics and the outer tube is highly tough, the diameter can be reduced without any restrictions on design freedom.
The advantage is that the material for the outer tube and the inner tube can be freely selected.

Furthermore, an excellent effect is achieved in that a uniform fitting margin can be obtained not only in the circumferential direction but also in the longitudinal direction, and a highly accurate double pipe can be obtained.

Therefore, the degree of freedom in design is increased without being restricted by the length of the double pipe, and the effect that the double pipe can be manufactured freely is achieved.

[Brief explanation of the drawing]

The drawings are schematic illustrations of embodiments of the invention of this application, and FIG. 1 is a partially cutaway schematic perspective view of one embodiment;
Fig. 2 is a perspective view of another embodiment equivalent to Fig. 1, Fig. 3 is a partial cross-sectional side view when the outer tube and inner tube are stacked relative to each other, and Fig. 4 is a partial cross-sectional view of the presser bending moment imparting mechanism by heating. , FIG. 5 is a perspective view of the diameter reduction mechanism via the presser bending moment due to cooling,
FIG. 6 is a cross-sectional view of a double pipe that has been reduced in diameter and self-tightened. 1...outer tube, 2...inner tube, 2', 2''...piece, 3...
double tube blank tube, 4... heating device, 5... cooling device, 6,
6'...Double pipe with wear-resistant lining.

Claims (1)

[Scope of Claims] 1. In a double-walled pipe in which the inner surface of the outer tube is lined with a wear-resistant material, the outer tube is tightened with a large number of pieces of the wear-resistant material in contact with the inner surface of the outer tube, and the inner surface is tightened. A wear-resistant inner-lined double pipe characterized by being tied together to form a tensioned pipe. 2 The outer tube is lined with a large number of pieces made of wear-resistant material to form an inner tube and layered relatively to each other to form a double-pipe tube, which simultaneously performs annular heating in the circumferential direction of the outer tube and cooling of the surrounding area. The thermal expansion of the heating part is restrained by the low temperature parts on both front and rear sides in the axial direction to suppress the expansion diameter, and then the heating part is cooled and stored so that the diameter of that part becomes smaller than the initial diameter, The wear-resistant device is characterized in that the double tube blank tube and the heating/cooling means are moved relative to each other in the axial direction so that the diameter of the outer tube after cooling is smaller than the initial diameter over the entire length of the heating section. Method for manufacturing double-lined pipes.