JPH028008B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for quenching a steel pipe whose entire length is at a predetermined quenching temperature. The present invention relates to a quenching method in which the entire steel pipe is uniformly cooled by cooling the entire steel pipe.

Conventionally, typical methods for quenching steel pipes that maintain a predetermined quenching temperature over the entire length include (1) external quenching using a ring nozzle, and (2) injecting water into the interior from the end of the steel pipe. Methods include internal hardening by injection and (3) a method in which the steel pipe is placed in a water tank and water is jetted inside using a nozzle close to the end.

In this case, in (1), for thick-walled steel pipes,
In addition to not being able to obtain a sufficient cooling rate, there may be differences in the amount of cooling water sprayed between multiple cooling injection rings or at the circumferential position of the rings, or misalignment between the center axis of the ring and the center axis of the steel pipe to be hardened. As a result, the cooling rate of the steel pipe to be quenched becomes uneven, causing bending, which not only causes defects in the quenched steel pipe itself, but also causes damage to the quenching equipment if the curvature becomes large. is necessary. In (2), the amount of cooling water is as above.
Although it is less than (1), in the case of thick-walled steel pipes, a sufficient cooling rate cannot be obtained, and the bending of the steel pipe between the supports that support the steel pipe to be quenched may affect the straightness of the steel pipe after quenching. has a considerable influence on Furthermore, the cooling rate is faster on the inlet side and slower on the outlet side, making it uneven in the longitudinal direction.
Hardening of long objects is difficult. (3) was made to solve the drawbacks of (1) and (2) above, but because the nozzle installed in the water tank is far from the end of the steel pipe, the resistance of the water in the tank There is a drawback that the cooling water velocity inside the steel pipe cannot be obtained sufficiently, and because the conditions of the upper and lower surfaces of the steel pipe in the water tank are different, it is difficult to obtain uniform external cooling in the lengthwise and circumferential directions. Can not. This is a decisive drawback, especially when cooling long steel pipes.
Both methods had many problems.

The present invention was made in order to solve the above problems, and it cools the steel pipe by adding cooling water to the outer surface or inner and outer surface of the steel pipe, and rotates the steel pipe during cooling and makes it reciprocate in the axial direction. To provide a quenching method that achieves uniform cooling over a short period of time. The present invention will be explained below using the drawings.

FIG. 1 is a plan view showing an outline of the present invention, FIG. 2 is a side view thereof, and FIG. 3 is a cross-sectional view taken along line AA in FIG. 2. In the figure, 1 is a hardened bed, 11a, 11b...
...11n, 12a, 12b, ...12n are steel pipes P
These support rolls are attached to a base 13 fixed to the quenching bed 1 at predetermined intervals. 14a, 14
b...14n and 15a, 15b...15n are tube axial direction transfer rolls arranged at a predetermined distance on both sides of the support rolls 11a to 11n and 12a to 12n. 16a, 16b to 16n are walking beams that feed the tube laterally, and are driven by a drive mechanism 17. Reference numeral 18 denotes a support member disposed in the longitudinal direction of the hardening bed 1 and above the support rolls 11a to 11n and 12a to 12n.
Arm 19 is placed opposite 11n and 12a to 12n.
a, 19b...19n are provided, and these arms 19a~
Clamp rolls 20a, 20b are installed at the bottom of 19n.
...20n and 21a, 21b...21n are attached. In addition, the support member 18 has a water pipe 2.
2 is disposed, and an external hardening device equipped with a flat nozzle 24 is attached to a slit 23 provided in the longitudinal direction of the lower surface thereof. Arms 19a, 19b...19
n is configured so that it can be rotated up and down by a drive mechanism 27.

FIG. 4 is a partial sectional view of an embodiment of an internal hardening head provided on one side of the hardening bed. In the internally hardened head 3, 31 is the head main body, and 32 is the main body 3.
It is a cylindrical body rotatably disposed within 1 via bearings 33, 33a. 34 is a hydraulic cylinder attached to the upper part of the main body 31, 36 is a motor, and 37 is a reducer that reduces the output of the motor 36, whose gear (not shown) meshes with a gear 38 fixed to the outer periphery of the cylindrical body 32. There is. A nozzle 39 is fixed to the tip of the cylindrical body 32, and can be replaced depending on the outer diameter of the steel pipe to be hardened.

4 is a clamp mechanism provided at one end of the cylindrical body 32. Reference numeral 40 denotes a movable element fitted to the cylindrical body 32 by means of a key and a keyway, or a spline, etc. so as to be able to slide only in the axial direction, and a groove 41 is provided on the outer periphery. Reference numeral 42 denotes a lever, one end of which is connected to the operating rod 35 of the hydraulic cylinder 34, and the other end rotatably connected to the main body 31 by a shaft 43. A pin 44 is provided approximately in the middle of the lever 42 and is fitted into the groove 41 of the movable element 40. 4
Reference numeral 5 denotes an approximately L-shaped clamp arm having one end connected to the movable element 40, and one end of which is connected to the cylindrical body 3 in the approximately central portion.
The other end of the lever 46 connected to 2 is connected.

45a is a clamp shoe installed at the tip of the clamp arm 45.

In this clamp mechanism 4, when the operating rod 35 of the hydraulic cylinder 34 moves forward, the lever 42 rotates clockwise about the shaft 43, and moves the movable element 40 connected via the pin 44 forward. When the movable element 40 moves forward, the clamp arm 45 is rotated counterclockwise by the lever 46, and the steel pipe P and the nozzle 39 are clamped by the clamp shoe 45a.

5 is a water pipe, 51 is a valve for controlling the amount of water to be fed, and the water pipe 5 and the cylindrical body 32 are watertightly connected by a coupling device 53 so that only the cylindrical body 32 can rotate.

Reference numeral 6 denotes a moving mechanism for reciprocating the quenching head 3 in the axial direction, and it consists of an arm 62 fixed to a member 61 connected to the main body 31, and a chain 63 to which this arm 62 is connected, and one sprocket 64 is a reversible sprocket. It is driven by a motor 66 and rotates left and right. As a result, the quenching head 3 is moved back and forth (in the axial direction) via the arm 62 and member 61 connected to the chain 63.

The operation of the apparatus of the present invention constructed as described above will be explained as follows. As shown in FIG. 1, the steel pipe P sent out from the previous process is transferred to the transfer roll 14.
It is fed in the axial direction over the hardening bed 1 by a to 14n, and stops when it hits the stopper 1a. At this time, the walking beams 16a to 16n operate to feed the steel pipe P laterally, and the supporting rolls 11a to 11n,
12a to 12n. Next, Figures 2 and 3
As shown in the figure, the arms 19a, 19b...19n are lowered, and the clamp rolls 20a-20n, 21a-
21n, lightly clamp the steel pipe P. on the other hand,
The tip of the steel pipe P is clamped by the clamp mechanism 4 with its end surface abutting against the end surface of the nozzle 39.

In this state, cooling water is sent from the water pipe 5 to the steel pipe P via the cylindrical body 32, and at the same time, the cooling water is supplied to the water pipe 22 provided on the support member 18, and the cooling water is supplied from the flat nozzle 24 over the entire length of the outer surface of the steel pipe P. A plate of cooling water flows down all at once. At this time, the motor 36 is driven to rotate the cylindrical body 38 and the steel pipe P connected thereto via the gear 38, thereby preventing bending caused by bending of the steel pipe P, and preventing the circumference of the steel pipe P. Cool direction evenly. Furthermore, the moving mechanism 6
The quenching head 3 and the steel pipe P are reciprocated in the axial direction, and the support rolls 11a to 11n, 12a to 1
2n and clamp rolls 20a to 20n, 21a
Since non-uniform cooling in the longitudinal direction by ~21n is also improved, it is effective in eliminating the occurrence of bending.

According to the embodiment of the present invention, in the conventional quenching by soaking in a pipe, the cooling rate is 32°C/sec, the bending of the steel pipe is 60mm/10m long, and in the quenching by immersion + water passage inside the pipe, the cooling rate is 55°C/sec, bend 35
mm/10m long (all test tubes had an outer diameter of 244.5mm x wall thickness of 13.5mm), whereas in the quenching method of the present invention, the outer diameter of 114.3mm x wall thickness of 4.5mm
For various sizes from mm to outer diameter 244.5mm x wall thickness 25mm,
As a result of using a lamina claw with a water flow rate of 10 m/secmax inside the pipe and a water flow of 500 T/H outside the pipe, a quenching cooling rate of 50°C/sec or more was obtained, and the bending was 10 mm/10 m.
Good results were obtained for longer periods.

Furthermore, according to the present invention, since the cooling rate is 50°C/sec or more as described above, if the entire length of the tube is cooled at once at this cooling rate, the temperature will be the same as room temperature if the quenching temperature is 920°C. Since the difference is 900℃, the time required for quenching is 18 seconds. This can be well matched to the cycle time of the hot rolling line, so that it can be directly connected to the hot rolling line.

In the above description, the case of internal and external surface hardening was described, but the present invention can also be applied to internal hardening by cooling only from the inner surface of the tube or external hardening by cooling only from the outer surface of the tube. Further, by driving and rotating the support roll at at least one location, twisting of the tube can be made less likely to occur when the quenching head is rotated. Alternatively, the clamp portion may be rotatably connected to the main body of the quenching head, the main body of the quenching head may be fixed, and the tube may be rotated by driving the support rolls. Further, each mechanism of the hardening apparatus of the present invention has been explained using the illustrated embodiment, but the present invention is not limited to this, and the same functions,
Other mechanisms may be used as long as they provide the same effects.

As is clear from the above description, according to the present invention, the steel pipe is cooled all at once over its entire length while rotating or reciprocating in the axial direction. can be cooled to Therefore, the quenching time of the steel pipe can be significantly shortened, allowing direct connection to a hot rolling line, and furthermore, the quality of the steel pipe can be improved.

[Brief explanation of drawings]

FIG. 1 is a principle plan view of an embodiment of the present invention, FIG. 2 is a side view thereof, and FIG. 3 is an enlarged sectional view taken along line AA in FIG. FIG. 4 is a partial cross-sectional view of an embodiment of the quenching head. P: steel pipe, 1: quenched bed, 11a, 12a: support roll, 18: support member, 22: water pipe,
3: Internal hardening head, 31: Main body, 32: Cylindrical body, 38: Gear, 4: Clamp mechanism, 5: Water pipe, 6: Moving mechanism.

Claims (1)

[Scope of Claims] 1. Platy cooling water is caused to flow down from above over the entire length of a horizontally placed steel pipe to be quenched, and the steel pipe to be quenched is rotated and cooled. In the quenching method, the steel pipe to be quenched is rotated and cooled while a plate-shaped cooling water is allowed to flow down from above the steel pipe to be quenched, and cooling water is added to the inner surface side from one end of the steel pipe to be quenched. A steel pipe quenching method characterized by reciprocating a steel pipe in the axial direction.