JPS629163B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention mainly relates to a controlled cooling method and apparatus for processing heat treatment, controlled processing (including rolling) + controlled cooling heat treatment, or controlled quenching of metal pipes such as seamless steel pipes and electric resistance welded steel pipes. 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. The recent drilling environmental conditions for oil or gas wells are as follows:
This situation is becoming increasingly difficult, 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 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 for "processing and/or controlled cooling of steel pipes" in a broad sense. 1 Intrusion of cooling water from the front or rear end and decrease in yield; For example, Japanese Patent Application No. 39494, No. 1983,
123849, U.S. Patent No. 3140964 (JuIy14,
1964) and No. 3507712 (Apr. 211970) etc. are basically used to prevent or prevent cooling water from entering from the tip or rear end of the steel pipe to be hardened. This invention was made to improve the non-uniformity of 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 inevitably enter from the rear end.
"Processing and/or Controlled Cooling of Steel Pipe" 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 reduced yield. This results in a fatal industrial disadvantage. In addition, in the case of the oblique injection cooling method, since the injected cooling water flows along the inner and outer walls of the steel pipe, it is difficult to control the cooling end temperature. In contrast,
The method disclosed in Publication No. 32097 is to create an annular tunnel at right angles to the steel pipe to be hardened and in space without exposing the thin filamentous "solid jet fluid" (in the form of droplets or mist) during flight. It has been proposed that cooling water can be prevented from entering from the ends by injecting it so as to form a . However, in this method, non-uniform cooling in the circumferential direction is obvious in the "processing and/or controlled cooling of steel pipes" method, which focuses on hardening and requires countermeasures against "hydraulic head difference" described later. 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 "hydraulic head difference" between the upper and lower headers. occurs, 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 extremely poor. This was particularly noticeable when the steel pipe was not cooled while being conveyed by rotation. 2. There is no countermeasure for "water head difference" and non-uniform cooling in the circumferential direction; since the conventional invention mentioned above targets quenching, the jetting pressure of the cooling water is about 0.35 to 6 kg.
f/cm ² G (header pressure), tunnel-type annular headers and other types of annular headers have only one cooling water (or refrigerant) supply port.
Because of this, the water supply piping is not complicated and the cooling system is simple. For this reason, when quenching steel pipes with a normal outside diameter range, in addition to rotating the steel pipes while conveying them on squee rolls, it is especially necessary to take measures such as water head differences to improve uneven cooling in the circumferential direction. Nakatsuta. According to research conducted by the present inventors, in the case of quenching, in conventional quenching cooling devices, the water head difference was within 10 to 15% of the header pressure at most. 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 directional cooling non-uniformity became very large. In such a case, the water head difference becomes a fatal drawback in the residual stress control cooling method after tempering, as described above. In addition, in the heat treatment of "processing and/or controlled cooling of steel pipes" in a broad sense, the cooling capacity (severity of
cooling) is relatively weak and sufficient in many cases. 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 can be low, and it is desirable to use less air, so measures are taken to improve the uniformity of cooling in the circumferential direction by taking measures against water head differences. The need arises. 3. The control range of cooling capacity is narrow and the controllability is poor;
In the case of quenching steel pipes, excluding the problem of quench cracking,
It is desirable that the severity of cooling be higher, and the cooling end temperature may be approximately 200° C. or less. In the case of ordinary external hardening of steel pipes, approximately 4 to 5 m ³ /unit surface area of the steel pipe is applied.
If a cooling water amount with an average water density of min.m ² 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, but this is not easy in practice as will be described later. However, the aforementioned U.S. Pat.
No. 3507712 and other cooling methods and devices, after the cooling water injected from the nozzle collides with the surface of the steel pipe,
Since the water flow is along the surface of the steel pipe in the direction of movement of the steel pipe, the amount of water is small. Therefore, when the jetting pressure (or flow rate) is low, it is strongly influenced by gravity and has a strong tendency to flow down to the bottom side of the steel pipe. Therefore, the uniformity of cooling in the circumferential direction deteriorates. Although some improvements have been proposed in the example of Japanese Patent Application No. 123849/1984, the above-mentioned tendency, that is, deterioration of the uniformity of cooling in the circumferential direction in the low water flow (density) cooling region, cannot be avoided. Also, in this example,
If both ends are left open, cooling water will enter from the pipe ends, making it unsuitable for controlled cooling. As described above, in the cooling devices that have been proposed primarily for quenching, the lower limit of the cooling capacity is high (close to quenching) due to constraints such as uniformity of cooling, and therefore the control width of the cooling capacity is limited. is narrow. Various types of controlled heat treatment of ordinary steel pipes In cooling, it is necessary to control the cooling intensity and cooling end temperature (or cooling temperature range) according to the pipe diameter and wall thickness, so it is practical to have a narrow control range of cooling capacity. The scope of application is 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) control range is narrow. As mentioned above, the present inventors have focused on the "processing and/or controlled cooling" of steel pipes of various sizes and wall thicknesses in a broad sense.
It is possible to use a single fluid refrigerant or a mixed spray cooling of gas refrigerant and liquid refrigerant suitable for heat treatment method and cooling end temperature control, and it has good uniformity of cooling, wide control range of cooling capacity, and easy cooling from the pipe end. We have invented a cooling method and device that allows uniform material to be obtained over the entire length without the infiltration of refrigerant, and which has an excellent shape (curvature, roundness, etc.) after cooling. 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. Furthermore, the cooling device uses only liquid refrigerant, and the jetting state can be selected from droplet-like or film-like. Furthermore, cooling with a gaseous refrigerant alone is also possible, such as blast cooling. As described 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, the cooling capacity can be controlled by controlling the weight ratio of air:water. Also,
Since the average water density can be controlled by changing the inner and outer diameters of the tunnel-shaped ring of refrigerant formed in the space, the present invention provides a cooling method and device that allows a very wide range of control over the cooling capacity. I can say that. The shape of the header and nozzle may be changed depending on the refrigerant jetting form or the refrigerant, but according to the experiments of the present inventors, the header structure nozzle described below has a large effect on the above-mentioned refrigerant selection and cooling capacity. It has been confirmed that control is possible. (2) There is no intrusion of cooling water from the pipe 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 no intrusion of cooling water from the tube ends, or even if there is, it is extremely small, so there is no actual damage at all. There is no “processing and/or controlled cooling heat treatment” of steel pipes in a broad sense.
Ideal for process use, providing uniform material over the entire length. The same applies to residual stress controlled cooling after tempering, which eliminates the need to cut off the tube end and improves yield, which is extremely advantageous industrially. The above was confirmed even when the inner diameter of the refrigerant tunnel ring formed in the space was significantly smaller than the outer diameter of the steel pipe to be cooled. (3) Very good cooling uniformity in the circumferential direction. Since the injection direction of refrigerant (including mixed refrigerant of gas and liquid) is perpendicular to the tube axis and almost tangential to the tube wall, a tunnel-shaped ring is formed in the space, and the refrigerant is injected from each header. The interaction of the refrigerant results in an almost uniform water density state, so the uniformity of cooling in the circumferential direction is extremely good. (4) It is possible and easy to control the cooling pattern in the longitudinal direction. In the oblique injection cooling method typified by U.S. Pat. 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 in practice there is almost no cooling pattern control. However, it was only suitable for hardening. Therefore, it was not possible to control the cooling end temperature. (This was not necessary with conventional hardening methods). but,
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. Particularly, in a steel pipe cooling device row in which the cooling devices are arranged in multiple stages, the cooling end temperature can be easily controlled. (5) A wide range of applications are possible, from various types of controlled cooling in a broad sense (including combination with processing heat treatment) to hardening. 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. Residual stress control cooling after tempering (patent application 1986-
(Refer to 2588, etc.) Rapid cooling treatment to prevent temper brittleness Non-thermal refinement process by online "controlled rolling and/or controlled cooling" heat treatment at the rear surface of the stretch reducer Ar ₁ transformation or less between the rear surface of the reeler and the reheating furnace,
An online process in which "sizing rolling and/or heat treatment" is performed once cooled and reheated to above the Ac ₃ transformation point. Heat treatment here means quenching, normalizing, etc.) "Quenching + tempering" (= refining heat treatment) by increasing the cooling end temperature in quenching to above the Mf point.
A process that makes the process continuous or simple, or a heat treatment process that omit 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. Figures 1 and 2 show an embodiment in which a large number of headers (16 in this example) arranged on the circumference are divided into three equal parts in the height direction to reduce the water head difference to one-third. In other words, to divide into three equal parts in the height direction, ∠
When AOB=θ, the relationship of equation (1) must be established geometrically. 2cosθ＝(1−cosθ) …(1) cosθ＝1/3 ∴θ＝70.5゜ …(2) From this relationship, if 16 headers 2 are arranged at equal intervals on the circumference, the upper and lower (respectively FAB, CDE)
By arranging 6 headers each and 2 headers each on the left and right (BC and EF, respectively), the water head will be reduced compared to the conventional cooling system that supplies cooling water from one location at the top or bottom. The difference can be reduced to almost 1/3. Next, three intermediate receiver tanks 1 (separately differentiated for air and water, but integrated) are defined as upper and lower zones (each with 6 headers) and left and right integrated zones (total of 4 headers). )
A method for supplying the required amount of air and water from the intermediate receiver tank to each header via a flow control valve, and a method for supplying air and water between the intermediate receiver tank and the header without using a flow control valve. was carried out. As a result, if the geometric head difference between each zone is less than approximately 20% of the maximum header pressure (water) during use, the air/water mixture or water-only refrigerant injected from each header will interfere with each other, causing The tunnel-type ring that is formed is almost uniform in the circumferential direction,
Uniform material quality or residual stress was obtained in the circumferential direction without using a flow control valve between the intermediate receiver tank and the header. In particular, when the steel pipe is conveyed and cooled while being rotated by ski rolls that are inclined in the horizontal plane, it is sufficient to maintain uniformity in the circumferential direction by simply adjusting the flow rate between the water pump or air compressor shown in Figure 2. Cooling was possible. In other words, the header group is 3 in the height direction as illustrated in Figure 1.
When divided into equal parts, most applications do not require a flow control valve between the intermediate receiver tank and the header.
It was also confirmed that in the case of rotation conveyance cooling using skie rolls, if the rotation speed of the steel pipe is 40 RPM or less, the effect of rotation cannot be expected to be much. Therefore, if rotational conveyance cooling is not used and more complete uniform cooling in the circumferential direction is desired,
The flow rate or header pressure may be controlled by increasing the number of divisions in the height direction or by using a flow rate control valve between the intermediate receiver tank and each header. Dividing the header into multiple blocks and controlling the ejection conditions (pressure, refrigerant amount, spray condition, etc.) of each header group is essentially advantageous in ensuring uniform cooling in the circumferential direction. . The reason for this is that in the field of heat transfer engineering, it has been clarified that heat transfer differs depending on the position of the heat transfer surface in space. This is because the ejection conditions can be controlled and uniform cooling can be achieved in the circumferential direction. Is the piping system diagram in Figure 2 for water only?
In the case of air/water mixed injection, two similar piping systems for water and air may be provided, and flow control valves 13 may be installed between the intermediate receiver tank 1 and each header 2 depending on the purpose or necessity. In addition, it is possible to connect water pipes and/or
Alternatively, appropriate header pressure or flow rate may be ensured directly from the blower piping to each header via a flow rate control valve. 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-tube structure, and water is sent from the inner tube 2B and air is sent from the outer tube 2A outside the header, and the air and water are internally mixed in the nozzle tip at the tip. It has a structure that allows it to spray 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 inside of the nozzle tip or the shape of the opening, for example, the shape of the air/water spray can be changed.
Full cone spray type, flat spray type, or any other shape can be selected. 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. Therefore, 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 shown in Fig. 3, even when the weight of air/weight of water is about 0.05 to 0.1, a fine droplet-like tunnel-type ring is formed, and residual stress control cooling after tempering occurs. The method was applicable to the method, and a sufficiently uniform residual stress could be secured in the circumferential direction. If the steel pipe to be cooled is thick and you want to increase the cooling capacity, increase the weight of the water while adjusting the balance of the air/water weight ratio, or increase the inner diameter of the tunnel ring formed in the space/to be cooled. By combining methods such as reducing the ratio of the outer diameter of the steel pipe, adjusting the droplet flow rate, and other methods of controlling the conveyance speed, it was possible to control the cooling capacity to a large extent and freely. In addition, even if the inner diameter of the tunnel ring is reduced to approximately 1/2 of the inner diameter of the steel pipe to be cooled, 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 longitudinal cross-sectional structural diagram of the double pipe type pipe header arranged in the plural pipe header parallel arrangement type annular header shown in FIG. 1. In order to make the quantitative distribution pattern of air, water, or air/water mixed jet uniform in the longitudinal direction and to prevent breathing, install an air rectifier plate 17 (Fig. 3) and install a 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. The adjustment mechanism for the inner diameter of the tunnel-type ring formed in the space is a header angle adjustment device 3 as shown in FIG.
By moving (rotating) manually or with an electric motor, each header is integrated via a header angle adjustment ring 30 by a connected rotation mechanism (details not shown), and the orientation of all nozzles is changed. . Further, in FIG. 1, an elevating device 4 is provided for aligning the center of the annular parallel header group with the center of the metal tube 16 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. It is being The uniformity of the 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" is compared with the known oblique jet cooling method.
Shown in the table. Table 1 shows the residual stress in the circumferential direction when residual stress control cooling after tempering is performed 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. This is a comparison of the maximum value of deviation (the difference between the maximum value and the minimum value in the residual stress distribution in the circumferential direction on the inner surface of the steel pipe). It can be seen that this shows that uniform cooling in the circumferential direction was achieved by forming .

[Table] As described above, uniformity of cooling in the circumferential direction is particularly required in various types of controlled cooling. The boiling heat transfer is dominant, and it is very difficult to control the cooling intensity with uniform cooling in the circumferential direction using water alone and diagonal injection cooling. However, the water head of the present invention With steel pipe cooling systems that take measures against the difference, the problem has almost been completely solved. As mentioned above, the metal pipe cooling device which takes measures against the water head difference and realizes uniform cooling in the circumferential direction and the longitudinal direction is a heat treatment method for "processing and/or controlled cooling" of various steel pipes in a broad sense. In terms of cooling intensity, it can be applied to a wide range of applications, from controlled cooling with (relatively) weak refrigerant injection conditions to quenching with strong cooling capacity. 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 industrial merits are enormous. In addition, the present invention injects the cooling medium at a given angle in the radial direction within a conical surface having an angle of, for example, ±20 degrees with respect to a plane perpendicular to the tube axis to form an annular tunnel of the cooling medium. However, it goes without saying that it can be applied industrially.

[Brief explanation of the drawing]

Fig. 1 shows an embodiment of the cooling device of the present invention, in which the header group is divided into three in the height direction in order to counteract the water head difference.
FIG. 2 is a cross-sectional view of a cooling device having a parallel array header with multiple pipe headers installed with an intermediate receiver tank. FIG. 2 is one embodiment of a piping flow rate control system diagram for a liquid or gas refrigerant in a 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. Fourth
The figure is a longitudinal sectional view of the header of FIG. 3.
FIG. 5 is a structural schematic diagram of an intermediate receiver tank employed in the cooling device shown in FIG. 1, which is installed around the outer periphery of a group of annular headers having a plurality of parallel pipe headers. 1: Intermediate receiver tank, 2: Double pipe header, 2A: Air header (outer pipe), 2B: Water header (inner pipe), 3: Header angle adjustment device, 4: Lifting device (centering mechanism) , 5:
Elevating 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) Type Air water spray nozzle), 11: Air supply port, 12: Water supply port,
13: Flow rate control valve, 14: Pressure gauge, 15: Flow meter, 16: Metal pipe, 17: Rectifier plate, 18: Intermediate receiver tank for air (chamber), 19: Intermediate receiver tank for water (chamber), 20: Piping port to each header (air), 21: Piping port to each header (water), 30: Header angle adjustment ring (linked with 3).

Claims (1)

[Claims] 1 Extending in the axial direction of the metal tube to be cooled, disposed at intervals in the circumferential direction, and capable of controlling pressure in units divided into a plurality of blocks in the circumferential direction. A given angle in a semi-longitudinal direction 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 almost perpendicular to the metal tube axis from a plurality of headers. A method for cooling a metal tube, characterized in that a cooling medium is injected at an angle to form an annular tunnel having a desired diameter, and a metal tube is cooled by passing through the annular tunnel. 2 A device that cools a metal tube by applying a cooling medium to its outer circumferential surface, which cools the metal tube 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 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.