JPS59205418A - Cooling process and device of metal tube - Google Patents

Abstract

PURPOSE:To achieve uniform cooling in the circumferential direction of a metal tube by passing said metal tube through the annular tunnel injecting cooling medium from a plurality of headers and having a desirable diameter. CONSTITUTION:The sixteen headers 2 arranged such that the headers are positioned in the axial direction of an objective metal tube 16 to be cooled and are simultaneously placed at same interval in a circumferential direction are equally divided into three parts in height-direction, whereby the difference of water- head is reduced to one third. The cooling medium-injecting angle of every divided unit of a plurality of the headers 2 divided into three parts is simultaneously changed by the same angle in the vertical or almost vertical plane to the axis of said metal tube 16. Thus, the annular tunnel injecting the cooling medium in the specified direction of the radial direction and having a desirable diameter, is formed. The metal tube 16 is cooled, passing the metal tube 16 through this annular tunnel.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention mainly relates to a controlled cooling method and apparatus for pipe processing heat treatment, controlled processing (including rolling), controlled cooling heat treatment, controlled hardening, etc.

The characteristics and applications of the controlled cooling method and device of the present invention will be specifically explained below using a heat treatment process for seamless steel pipes or electric resistance welded steel pipes as an example.

Recently, the environmental conditions for drilling oil or gas wells have become increasingly severe, and with the drop in crude oil prices, the need for inexpensive, high-quality steel pipes is increasing. In order to respond to these situations and needs, it has become essential to put non-thermal refining, online processing heat treatment in a broad sense, and controlled cooling processes into practical use, as seen in advances in thick plate manufacturing methods. However, the cooling methods and devices that have been proposed so far are mainly aimed at quenching, and have various problems as described below. However, not enough devices have been proposed yet.

The following is a summary of the shortcomings and problems when the cooling methods and devices that have already been proposed are applied to heat treatment methods in the broad sense of "processing and/or controlled cooling of steel pipes."

1) Infiltration of cooling water from the leading or trailing end and decrease in yield; For example, Japanese Patent Application No. 1987-39/194, Japanese Patent Application No. 1983-1
23849, U.S. Pat. No. 3,140,964 (Ju.
ly14.

1964) and No. 3,507,712 (AI) r.
21.1970) etc., the methods and devices disclosed in
Basically, this invention was made to prevent or prevent cooling water from entering from the tip or rear end of a steel pipe to be hardened, or to improve non-uniform cooling in the circumferential direction.

In the method of injecting cooling water obliquely in the direction of progress of the steel pipe to be quenched, if a lid is not attached to the rear end of the steel pipe, the cooling water will always enter from the rear end, causing problems in "steel pipe processing and/or controlled cooling." In various broadly defined controlled cooling methods such as heat treatment methods and residual stress controlled cooling methods, there are parts where the material quality and residual stress cannot be controlled, resulting in cut-off parts and lower yields7, which is fatal in industrial terms. be disadvantageous to However, in the case of the oblique injection cooling method, it is difficult to control the cooling end temperature because the injected cooling water flows along the inner and outer walls of the steel pipe. On the other hand, the method disclosed in Japanese Patent Publication No. 53-32097 does not expose thin filamentous "solid jet fluid" during flight (in the form of droplets or mist), and it It has been proposed that cooling water can be prevented from entering from the ends by injecting the water at right angles to the water so as to form an annular tunnel in the space. However, this method
In steel pipe machining and/or controlled cooling methods that focus on hardening and require countermeasures against the water head difference described below, non-uniform cooling in the circumferential direction is obvious. This is because cooling water is supplied to each of the many headers arranged parallel to the steel pipe to be hardened without going through a flow rate or pressure adjustment mechanism, so there is a "head difference" between the upper and lower headers. °, and cooling is not uniform in the circumferential direction.

As will be described later, when this cooling method was applied to the residual stress control cooling method after tempering, the uniformity of the residual stress in the circumferential direction was very poor. This was particularly noticeable when the steel pipe was not cooled during rotational transportation.

2) Non-uniform cooling in the circumferential direction because there is no countermeasure against water head difference; Since the conventional invention mentioned above targets quenching, the jetting pressure of the cooling water is about 0.35 to 6 kg [/CrA
G (header pressure), tunnel-type annular headers and other types of annular headers only have one cooling water (or refrigerant) supply port, which makes the water supply piping simple and simple. It is a cooling device.

To avoid this, when quenching steel pipes with a normal outside diameter range, in addition to rotating the steel pipes while conveying them with skew rolls, it is necessary to take measures such as water head difference measures to improve uneven cooling in the circumferential direction. There was no particular need.

According to the research conducted by the present inventors, when quenching is targeted, in conventional quenching cooling equipment, the water head difference is at most 10 to 10% of the header pressure.
It was within 15%.

In the post-tempering residual stress control cooling method described below, in the case of the conventional annular header with one cooling water supply port (upper or lower), the water head difference can reach 50 to 85%, and the circumference The non-uniformity of cooling in the direction was very large.

In such a case, as described above, in the residual stress control cooling method after tempering 7, the water head difference becomes a fatal drawback.

However, in the heat treatment of "processing and/or controlled cooling of steel pipes" in a broad sense, there are many cases where the cooling capacity is relatively weak and sufficient compared to the case of quenching, as in the previous example.

In such a case, the header pressure may be low because the amount of water or the average water density may be small. The same is true for mixed spray cooling of air and water; the water pressure may be low, and it is desirable to use less air, so countermeasures against the water head difference should be taken to improve the uniformity of cooling in the circumferential direction. The need arises.

3) The control range of the cooling capacity is narrow and the controllability is poor; in the case of quenching steel pipes, excluding the problem of quench cracking, the cooling strength is
The higher the degree of cooling (everity of cooling) is, the more desirable it is, and the cooling end temperature should be about 200"C or less. In the case of normal external hardening of steel pipes, about 4 to 5 yj:/In + per unit surface area of the steel pipes. 11.7
If an amount of cooling water having an average water density of fj is supplied, the cooling capacity is almost saturated. Therefore, in order to reduce or control the cooling capacity, it is sufficient to mainly control the average water flow density. 3,507,
In No. 712 and other cooling methods and devices, the cooling water injected from the nozzle collides with the surface of the steel pipe and then flows along the surface of the steel pipe in the direction of movement of the steel pipe, so the amount of water is small, and therefore the jetting pressure (or flow rate) is low. If it is low, it will be strongly influenced by gravity and will have a strong tendency to flow down to the lower surface of the steel pipe, resulting in poor cooling uniformity in the circumferential direction.

Although some improvements have been proposed in the example of Japanese Patent Application No. 123,849/1984, the above-mentioned tendency, that is, the uniformity of cooling in the circumferential direction in the low water flow (density) cooling region is unavoidable. In addition, in this example, when both ends are left open,
Cooling water enters from the tube end, making it unsuitable for controlled cooling.

As described above, in the cooling devices that have been proposed mainly for the purpose of hardening, due to constraints such as uniformity of cooling,
The lower limit of cooling capacity is high (close to quenching), and therefore the control range of cooling capacity is narrow.

In various controlled heat treatment cooling of ordinary steel pipes, pipe diameter,
Since it is necessary to control the cooling intensity and cooling end temperature (or cooling temperature range) according to the wall thickness, if the control range of the cooling capacity is narrow, the practical application range will be limited.

In the method disclosed in Japanese Patent Publication No. 53-32097, water is used as the fluid refrigerant for industrial purposes, and the lower limit of the cooling capacity is similarly high, since water is used as a "solid fluid jet flow" and exposure is avoided. (cooling capacity) has a narrow control range.

As mentioned above, the present inventors have discovered that a fluid refrigerant alone or a mixture of a gas refrigerant and a liquid refrigerant is suitable for the "processing and/or controlled cooling" heat treatment method of steel pipes of various sizes and wall thicknesses in a broad sense, and for controlling the cooling end temperature. Spray cooling can also be used for cooling, the cooling is uniform, the cooling capacity can be controlled over a wide range, there is no infiltration of refrigerant from the pipe end, uniform material is obtained over the entire length, and the shape after cooling (bent, Invented a cooling method and device with excellent roundness, etc.

The features and uses of the cooling method and device of the present invention are summarized as follows.

(1) High degree of freedom in selecting refrigerant in the same cooling device;
Wide control range of cooling capacity.

Mixed spray cooling of gas and liquid refrigerant, such as mixed air-water spray cooling for steel pipes, is possible and optimal. However, it is still a cooling device using only liquid refrigerant, and the ejection state can be selected to be droplet-like or film-like. Furthermore, cooling with a gaseous refrigerant alone is also possible, such as blast cooling.

As mentioned above, there is a high degree of freedom in selecting the refrigerant and its jetting form, and in the case of air/water mixed spray cooling, for example, air:
By controlling the weight ratio of water, it is possible to control the cooling capacity.

Furthermore, the average water density can be controlled by changing the inner diameter of the tunnel-shaped width ring of the refrigerant formed in the space, so it can be said that the cooling method and its apparatus have a very wide control range of cooling capacity.

Although the shape of the header and nozzle may be changed depending on the refrigerant jetting form or the refrigerant, according to the experiments of the present inventors, the header structure nozzle described below is suitable for the selection of refrigerant and the cooling capacity. It has been confirmed that significant control is possible.

(2) There is no intrusion of cooling water from the tube end, improving yield.

In the cooling method of the present invention, the refrigerant is injected in a direction perpendicular to the tube axis, so even if both tube ends are open, there is little intrusion of cooling water from the tube ends, or even if there is, it is completely injected. There is no actual damage, and it is ideal for the "processing and/or controlled cooling heat treatment" of steel pipes in a broad sense, and uniform material quality can be obtained over the entire length. The same applies to residual stress controlled cooling after tempering, which eliminates the need to discard the pipe end and improves yield, which is extremely advantageous for the second industry. The inner diameter of the refrigerant tunnel ring formed in the space is significantly smaller than the outer diameter of the steel pipe to be cooled. 3) The uniformity of cooling in the circumferential direction is very good.

Since the injection direction of refrigerant (including mixed refrigerant of gas and liquid) is perpendicular to the pipe axis and almost tangential to the pipe wall, a tunnel-shaped ring is formed in the space, and from each header The interaction of the injected refrigerant results in a nearly uniform water volume and density, resulting in extremely good cooling uniformity in the circumferential direction.

(4) It is possible and easy to control the cooling pattern in the longitudinal direction.

In the oblique injection cooling method represented by U.S. Patent No. 3,507,712, the refrigerant injected from the nozzle row in the previous stage accumulates as it goes to the latter stage (in the direction of travel), so it is actually possible to control the cooling pattern. It was almost impossible to do so, and 7 was not suitable for hardening. Therefore, it was not possible to control the cooling end temperature. (Unnecessary with traditional hardening methods). However, with the cooling method and cooling device of the present invention, it has become possible to easily control the cooling pattern in the longitudinal direction, and it has also become possible to control the cooling end temperature.

(5) A wide variety of controlled cooling (including combination with processing heat treatment) to quenching (in a broad sense) enables a wide range of applications.

Typical examples of the uses of the cooling method and apparatus of the present invention are as follows, but they are not limited to these uses.

(1) Residual stress control cooling after tempering (%
588, etc.) (2) Rapid cooling treatment to prevent temper brittleness (β) On-line rili controlled rolling and/or controlled cooling on the rear surface of the trench retoucher. After A+"1 transformation and t- between furnaces, once cooled and reheated to Ac3 transformation point or higher [rolling (S
On-line process of ``quenching, rolling) and/or heat treatment'' (heat treatment here means quenching or standard, etc.) ■ ``Quenching and tempering'' (-quenching and tempering) by increasing the cooling end temperature in quenching to ``2'' above the Mf point. A heat treatment process that makes the heat treatment process continuous or simplified, or a heat treatment process that omits the tempering process for line pipes, etc.

Next, the cooling device of the present invention will be explained based on an embodiment with reference to the drawings shown below.

In Figures 1 and 2, a large number of headers (16 in this example) arranged on the circumference are divided into three equal parts in the height direction, and the water head difference is set to 1.
This is an example in which the number is reduced to /3. That is, in order to divide it into three equal parts in the height direction, / A, OB = θ, then
Geometrically, the relationship in equation (1) must hold true.

2CO5θ=(1-cosθ)...(1) cosθ=
I/3,°, θ-705°...(2) From this relationship,
When 16 headers 2 are arranged at equal intervals on the circumference, there are 6 headers each on the top and bottom (FAIJ, CI, E),
When arranging two tubes on the left and right (IC and EF respectively), the water head difference is approximately 1/3 compared to a conventional cooling system that supplies cooling water from one location at the top or bottom. Can be reduced.

Next, the upper and lower zones (each header has 6 cylinders) and the left and right sides are integrated zones (total of 4 headers), and three intermediate receiver tanks 1 (separately differentiated for air and water, but not integrated) are installed. ) and supplying the required amount of air and water from the intermediate receiver tank to each header via a flow rate control valve; We implemented a method of supplying As a result, if the geometric head difference in each zone is less than about 20% of the maximum rudder pressure (water) during use, the air/water mixture injected from each header and the water-only refrigerant will interfere with each other. The tunnel-shaped ring formed in the space is almost uniform in the circumferential direction, and uniform material or residual stress can be obtained in the circumferential direction without the need for a flow control valve in the intermediate receiver tank header. It was done.

In particular, when controlling and cooling steel pipes by rotating them using skew rolls with the transport rolls tilted in the horizontal plane, it is sufficient to adjust the flow rate between the water pump or air compressor shown in Figure 2 in the circumferential direction. Uniform cooling was possible. In other words, a group of headers as illustrated in Figure 1,
Dividing into three equal parts in the height direction eliminates the need for a flow control valve between the intermediate receiver and the tank header in most applications.

It was also confirmed that in the case of rotation conveyance cooling using skew rolls, if the rotation speed of the steel pipe is 4QR, PM or less, the effect of rotation cannot be expected to be much.

Therefore, if rotary conveyance cooling is not used and more complete uniform cooling in the circumferential direction is desired, the number of divisions in the height direction may be increased, or the flow rate between each header of the intermediate receiver tank may be increased. The flow rate or the header pressure can be controlled via a regulating valve.

The piping system diagram in Figure 2 is for water only, or in the case of air/water mixed injection, two similar piping systems are provided for water and air, and an intermediate receiver tank 1 is installed depending on the application or necessity. Flow control valves 13 may be installed between each header 2. Alternatively, L7 may be used so that an appropriate header pressure or flow rate can be directly secured from the water supply piping and/or ventilation piping to each header via a flow rate control valve without installing an intermediate receiver tank. However, installing an intermediate receiver can reduce and stabilize fluctuations in header pressure or flow rate.

FIG. 3 is a sectional view of the header including the nozzle mounting portion. The header of this embodiment has a double pipe structure, and water is sent from the inner pipe 2B and air is sent from the outer pipe 2A on the outside, and the air and water are internally mixed in the nozzle tip at the tip.
It has a structure that allows it to spray air and water spray particles.

However, as mentioned above, it is also possible to inject water alone or air alone, which has the advantage of being able to be used selectively depending on the application or required cooling rate.

In addition, by changing the shape of the inside of the nozzle tip or the opening, for example, the shape of the air/water spray can be selected from a full cone spray type, a flat spray type, or any other arbitrary shape. However, in the inventor's hot experiments, the thickness of the tunnel-shaped ring formed in the space is thinner in the flat spray type shape, so the refrigerant concentration is higher and the refrigerant density is also higher. Cooling capacity is improved.

Next, a method for controlling the cooling capacity will be explained using air-water mixed spray cooling as an example. In the case of the internal mixing air/water nozzle illustrated in FIG. 3, the air weight/water weight: 1o, o5~0.
Even at a level of 1, fine droplet-like tunnel-shaped rings are formed.
It can be applied to the residual stress control cooling method after tempering 2, and a sufficiently uniform residual stress in the circumferential direction can be ensured. If the steel pipe to be cooled is thick and you want to increase the cooling capacity, you can increase the weight of the water while adjusting the air/water weight ratio, or increase the inner diameter of the tunnel ring formed in the space. By combining methods such as reducing the ratio of the outer diameter of the steel pipe to be cooled, adjusting the droplet flow rate, and controlling the relaxation feed rate, it was possible to greatly and freely control the cooling capacity. .

Even if the inner diameter of the tunnel ring is reduced to about 1/2 of the inner diameter of the steel pipe to be cooled, the refrigerant, especially water, will not enter from the tip of the steel pipe during transportation, and the entire length of the steel pipe will be reduced. Uniform material quality or residual stress was obtained throughout.

FIG. 4 is a structural diagram of a longitudinal cross-section of the double pipe type pipe header arranged in a circular hexagonal arrangement of the plurality of pipe headers shown in FIG. 1. In order to make the quantitative distribution pattern of air, water or air/water mixture jet uniform in the longitudinal direction and to prevent breathing, install an air rectifier plate 17 (Fig. 3) and install a rectifier plate 17 in the inner water pipe. It has been confirmed through experiments that it is better to make the suction port of the water nozzle 9 protrude to about the center of the inner tube.

By moving (rotating) the tunnel-type annular inner diameter adjustment device 3 formed between the holes manually or with an electric motor, each header unites as a unit with a connecting rotation mechanism (details not shown) and the orientation of all nozzles is changed. It is now possible to do so. Further, in FIG. 1, an elevating device 4 is provided to keep the center of the group of annular parallel headers and the center of the metal tube 16 coincident even if the diameter of the pipe to be cooled changes. 5 is a frame that is raised and lowered by the device 4.

Note that FIG. 5 shows an example of the structure of the intermediate receiver tank shown in FIG. .21 is provided.

Table 1 shows the uniformity of residual stress in the circumferential direction when the cooling device of the present invention is applied to the "residual stress control cooling method after tempering 2" in comparison with the known oblique jet cooling method. . Table 1 shows the residual stress in the circumferential direction when residual stress control cooling is performed after tempering 7 using a water-only diagonal injection cooling system (conventional old method) that does not take measures against water head difference and the cooling system of the present invention. (the difference between the maximum and minimum values in the residual stress distribution in the circumferential direction on the inner surface of the steel pipe). It can be seen that by forming the ring, uniform cooling could be achieved in the circumferential direction.

Thus, especially in various types of controlled cooling, uniformity of cooling in the circumferential direction is particularly required.

Since nucleate boiling heat transfer is dominant, it is extremely difficult to control the cooling intensity while achieving uniform cooling in the circumferential direction using water alone and diagonal injection cooling.However, the present invention's water head difference With the steel pipe cooling system that took measures, the problem was almost completely resolved.

As mentioned above, the cooling device for metal pipes that takes measures against the water head difference of the present invention and achieves uniform cooling in the circumferential direction and longitudinal direction can be used for [processing and/or plagiarism 1 cooling] of various steel pipes in a broad sense. It is most suitable for heat treatment methods, etc., and can be applied to a wide range of applications, from controlled cooling with (relatively) weak refrigerant injection conditions to quenching with strong cooling capacity, even in terms of cooling intensity. Therefore, a desired cooling pattern can be easily realized in a steel pipe cooling device row in which the cooling devices are arranged in multiple stages, and the first commercial advantage is enormous.

In addition, in the present invention, for example, ±20
Of course, it is also possible to apply the method industrially by injecting the cooling medium at a given angle in the radial direction within a conical surface having an angle of .degree. C. to form an annular tunnel of the cooling medium.

[Brief explanation of drawings]

Figure 1 shows one embodiment of the cooling device of the present invention, in which a group of headers is divided into three parts in the height direction in order to counteract the water head difference, and an intermediate receiver is divided into three parts in the height direction.
Cross-sectional view of a cooling device with a parallel arrangement of multiple pipe headers equipped with tanks. FIG. 2 is one embodiment of a liquid or gas refrigerant piping-flow control system diagram of the cooling device of the present invention, and corresponds to FIG. 1. FIG. 3 is a detailed cross-sectional view of the double-pipe air-water mixing header. 4 is a longitudinal sectional view of the header of FIG. 3; FIG. FIG. 5 is a structural schematic diagram of an intermediate receiver tank employed in the cooling system shown in FIG. 1, which is installed around the outer periphery of a group of annular headers of a plurality of parallel pipe headers. ■= Intermediate receiver tank 2: Double pipe hesodar 2A: Air header (outer pipe) 213: Water henoter (inner pipe): 3: Header angle adjustment device 1: Lifting device (centering mechanism) 5 knees 5'l
Descending frame (centering mechanism) 6: Metal tube support conveyance roller 7: Water piping (for liquid refrigerant) 8: Air piping (for gas refrigerant) 9: Water nozzle 10: Air nozzle (internal mixing air-water spray nozzle) ) 11: Air supply port + 12: Water supply port 13: Flow rate adjustment valve ・14: Pressure gauge 15: Flow meter ・16: Metal pipe ・17: Rectifier plate 1
8: Air intermediate receiver tank (chamber) 19:
Intermediate water receiver tank (chamber) 20: Piping to each header (air) 21: Piping port to each header (water) Patent applicant Representative patent attorney Tomoyuki Ya Fuki (and one other person) -・r Thread completion letter (spontaneous) 1981 6 R/% Nippon Tokusoku 1:1 Director-General Kazuo Wakasugi, 1981 Special revision application No. 80095 2 Name of the invention Metal pipe Cooling power method and equipment 3, drawing 1]-Relationship with the IS case Applicant address: 6-3 Otemachi Knee-chome, Chiyoda-ku, Tokyo Name
(665) Nippon Steel Corporation (and 1 other person) 4, 11 agents 704, 6-4-21 Akasaka, Minato-ku, Tokyo
(584) 7022 (1 other person) 5. Detailed description of the invention in the subject specification of Sleeve 11-, is-, "1.5
6. Details of the amendment (1) "Inner diameter" on page 10, line 18 of the specification is corrected to "inner diameter and outer diameter." (2) On page 10, line 1 of the specification, ``It is now possible.'' Next to J, ``In particular, it becomes easy to control the temperature of the cooling path r in a row of cooling devices for steel pipes in which the cooling devices are arranged in multiple stages.'' Insert.・L Continued City Authorization (Spontaneous) i Kyowa 5B August/1 Patent 1i Director-General Kazuo Wakasugi 1 ・Indication of 1980 Patent Application No. 80095 2 Title of Invention Method for Cooling Metal Pipe and Device 3, Person making the amendment/Relationship with the matter Applicant Address 2-6-3 Otemachi, Chiyoda-ku, Tokyo Name (
665) Nippon Steel Corporation (and 1 other person) 4, f (Register 5, subject of sleeve 11 Detailed explanation of the invention in the specification, brief explanation of the drawings, drawing 6, contents of amendments (1) Specification On page 20 of the book, line 4, “Force each person.”
□Correct it to ``Each header is adjusted through the header angle adjustment ring 30.'' (2) Insert the following sentence between lines 18 and 19 on page 25 of the specification. "30: Header angle adjustment ring (linked with 3)" (3)
Figure 1 of the attached drawings is corrected as shown in the attached sheet. (Issue of procedural amendment) January 30, 1980 't'+ +i'II+'' Mr. Kazuo Wakasugi, Director General 1.41 indications 1982 Patent Application No. 80095 2 Title of invention Method for cooling metal pipes and Applicant 3: Relationship with the Supplementary II Case Applicant Address 2-6-3 Otemachi, Chiyoda-ku, Tokyo Name (
665) Nippon Steel Corporation (and 1 other person) 4. Agent Address: 704, 6-4-21 Akasaka, Minato-ku, Tokyo (
584) 7022 5. Detailed explanation of the invention of the subject specification of Supplement iE 6. Contents of amendment (1) The following sentence is added after the last line of page 16 of the specification.

Claims (2)

[Claims] (1) A plurality of headers that extend in the axial direction of the metal tube to be cooled, are arranged at intervals in the circumferential direction, and are able to control pressure in units divided into a plurality of blocks in the circumferential direction. The cooling medium is injected at a given angle with respect to the radial direction, which is set by a nozzle angle adjustment mechanism that simultaneously changes the cooling medium injection direction by the same angle in a plane perpendicular or approximately perpendicular to the metal tube axis. A method for cooling a metal tube, comprising: forming an annular tunnel having a desired diameter; and cooling the metal tube by passing the metal tube through the annular tunnel. (2) A device that cools a metal tube by applying a cooling medium to the outer circumferential surface of the metal tube, in which the cooling medium is applied in units of a plurality of blocks extending in the axial direction of the metal tube and divided at least in the circumferential direction. a plurality of headers each having a pressure control mechanism for controlling pressure; a nozzle for injecting a cooling medium from the header onto the outer circumferential surface of the metal tube; A cooling device for a metal tube, comprising a nozzle angle adjustment mechanism that simultaneously changes the angle between the cooling medium injection direction and the radial direction of the metal tube by the same angle.