JPS63183127A - Method for hardening outside surface of steel pipe - Google Patents

Abstract

PURPOSE:To uniformly harden steel pipes without generating uneven cooling thereof by injecting a cooling liquid for hardening from auxiliary headers for cooling outside surfaces to the non-immersed outside surfaces of the steel pipes simultaneously when the heated steel pipes are immersed into the liquid in a hardening tank. CONSTITUTION:The heated steel pipes 1 are cross fed and are imposed on dogs 10 mounted to an inclined chain conveyor 9. The pipes 1 are then moved diagonally downward along skids 8 by the circulative driving of the conveyor 9. The cooling liquid for hardening is injected over the entire outside surface of the non-immersed parts of the pipes 1 from nozzles 11 of the auxiliary headers 3 for cooling the outside surfaces when the pipes 11 are immersed into the quenching liquid 2 in the hardening tank 5. The pipes 1 are in succession submerged into the liquid 2 and are imposed on turning rollers 6 rotated by revolving shaft 12. The pipes 1 are clamped by clamping rollers 7 and are rotated. The cooling liquid is simultaneously injected from the nozzles of the headers 18 to the outside surfaces of the pipes 1. The pipes 1 are thereby uniformly and stably cooled and hardened, and the hardening quality of the outside surfaces is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for hardening the outer surface of a P# tube by a dipping method.

[Prior art]

One way to make steel pipes higher tensile strength, higher toughness, and other high-grade properties is to subject them to quenching and tempering treatments like other steel products. In recent years, as a method for quenching steel pipes, due to problems such as larger diameters and thicker walls of steel pipes and improved productivity, steel pipes heated to a constant temperature of nr are eroded in water as a liquid cooling medium, and the inner and outer surfaces of the steel pipes are quenched. Conventionally, a method of hardening is used.

The conventional method for quenching steel pipes will be explained with reference to FIG. After a part (lower part) of the steel pipe comes into contact with the quenching tank liquid 2 as shown, the steel pipe continues to settle into the quenching tank liquid 2 and completely enters the quenching tank liquid 2 as shown by reference numeral 1B. The steel pipe 1 is then placed on a pair of turning rollers 6, and then, with the pair of Franz rolls 7 pressed against the upper part of the steel pipe 1 placed on the turning rollers 6, the steel pipe 1 is rolled by the turning rollers 6. This was passed down orally, and quenching of the steel pipes was started (see Japanese Patent Laid-Open No. 60-37859).

[Problems that inventions try to solve]

However, in the case of the conventional steel pipe quenching method, the period from when the MW before quenching lands on the quenching tank liquid 2 as shown by reference numeral 1A until it is completely immersed in the quenching tank liquid 2 as shown by reference numeral 1B. During quenching, the cooling timing of the outer surface of the steel pipe in the circumferential direction by the quenching bath liquid 2 is different, and as a result, a temperature difference occurs in the circumferential direction of the steel pipe before quenching, so uneven heating occurs in the circumferential direction of the steel pipe. In addition, there were drawbacks that caused quality problems, such as promoting the size and shape of the steel pipe, especially the out-of-roundness.

As a countermeasure to this problem, it is possible to increase the conveyance speed of the charging conveyor 4, but if the conveyance speed is increased too much, the collision force of the copper tube 1 against the turning roller 6 will become large, causing the steel tube 1 to become dented and deformed. A problem arises in which

As another measure, we added a reverse feed chenna to the charging conveyor to increase the number of turns at the steel pipe inlet.
It is possible to increase the rotation speed when the pipe starts to be immersed in the liquid in the quenching tank, but in this case, if the steel pipe has some bending deformation, vibration will occur due to the high speed rotation of the steel pipe, so it is necessary to stabilize the steel pipe. A problem arises in that it cannot be transported.

Therefore, in the conventional method of quenching pipes using the immersion method, when the steel pipe is immersed in the quenching bath liquid, it is possible to avoid the inevitable occurrence of a cooling time lag in the circumferential direction of the outer surface of the steel pipe. As a result, the steel pipe becomes unevenly cooled and a temperature difference occurs before quenching, which causes uneven quenching and shape deterioration. The problem was that I couldn't do it.

[Purpose and structure of the invention]

An object of the present invention is to provide a method for quenching the outer surface of a steel pipe that can advantageously solve the above-mentioned problems. When the heated steel pipe 1 comes into contact with the quenching bath liquid 2 during quenching and cooling by being conveyed and immersed in water, the quenching cooling liquid is injected from the external auxiliary cooling header 3 onto the non-liquid outer surface of the steel pipe 1. A method for quenching the outer surface of a steel pipe is characterized in that:

〔Example〕

Next, this explanation will be explained in detail using an illustrated example.

Figures 1 and 2 show a first embodiment in which the present invention is applied to an inclined transmission conveyance type external hardening method, in which a heated steel pipe 1 is moved laterally by a kicker skid. After being conveyed, the chenoconveyor 9 with a charging dog waits at the top of the slanted charging skid 8. The chenoconveyor 9 with dogs is driven in circulation and moved diagonally downward along the charging skid 8 at the set speed of the chenoconveyor 9 with dogs for mv1-s charging. External auxiliary cooling headers 3 installed above and below the
The cooling liquid for quenching is inserted into the steel pipe 1 from the multiple nozzles 11 in each outer surface auxiliary cooling header 3 at the same time as the liquid passes through the space between the tubes and the steel pipe 1. It is sprayed over the entire outer surface of the liquid part, and then the steel pipe 1 is
After being further moved downward and immersed in the quenching bath liquid 2, it is placed on a large number of turning rollers 6 fixed to a pair of rotating shafts 12 at intervals.

Next, by the shortening operation of the roll moving fluid pressure cylinder 36, the support arm 14 fitted to each rotating shaft 72 is rotated via the length-adjustable rod 13, so that each support arm 1
Clamp roll 7 is rotatably attached to the end of 4! '11 (Pressed against the upper part of D, the steel pipe 1 is held in place by each turning roller 6 and each crank roller lure, and then the fA4W1 is rotated by the drive device via the rotating shaft 12 and the turning roller 6, and In the quenching bath liquid 2, the cooling liquid is injected onto the outer surface of the nozzle *yi of the outer surface cooling header 18 provided on both the left and right gI11 of the steel pipe 1, and the copper pipe 1 is quenched.

After quenching the steel pipe 1, the fluid pressure cylinder 3
6), each support arm 14 is rotated in the opposite direction, and each clamp 20-7 is retracted from the top of the steel pipe 1 to the side, and then the chain conveyor 1 with an unloading dog is moved.
5 is driven in circulation, and the steel pipe 1 after quenching is carried out along an inclined carrying-out skid 17 by a dog 16 of the conveyor 15 with a carrying-out dog.

In this invention, when the tube 1 comes into contact with the quenching bath liquid 2, the outer iM auxiliary cooling header 3 is used to cool the copper v7vc.

This feature is characterized by injecting the quenching cooling liquid onto the outer surface of the insertion liquid section in the case, so this point will be explained in detail with reference to FIG. 2.

@Two external auxiliary cooling headers 3 extending in the longitudinal direction of the pipe are provided above the middle part of the charging skid 8, and
One nozzle 11 is provided above the quenching bath liquid 2 below the middle part of the charging skid 8, and a large number of nozzles 11 in each outer surface auxiliary cooling header 3 are used to remove the steel pipe 1 immediately after it has landed on the quenching bath liquid 2. The cooling liquid for quenching is arranged so as to be injected onto the outer surface of the non-temperature liquid part, and furthermore, a position detection sensor 19 is arranged above the position before the steel pipe 1 comes into contact with the liquid. The time of liquid accumulation in the steel pipe 1 is detected, and based on the detection signal, the electric pulp 22 of the liquid supply pipe 21 to the external auxiliary cooling header 3 is sent via the sequencer 2°.
is opened, and almost at the same time as the liquid is deposited on the steel pipe 1, the quenching coolant is injected from the nozzle 11 of each external auxiliary cooling header 3 toward the outer surface of the non-cooling part of the steel pipe 1. The temperature in the circumferential direction is kept uniform.

Note that the above-mentioned series of operations is performed in seconds, so the outer diameter of the steel pipe, the wall thickness, the number of revolutions, The sequencer 20 is adjusted according to the conveyance speed and the like.

Piston rods 27 of a plurality of distance adjustment fluid pressure cylinders 25 are connected to the external auxiliary cooling header 3 via cooling liquid headers 26 for external auxiliary cooling nozzles, and the cylinders of the fluid pressure cylinders 25 are fixed to the cross beam 24. The outer surface of the steel pipe 1 and the nozzle 1 of the outer auxiliary cooling header 3 immediately after the liquid has been applied
3 is adjusted by moving the external auxiliary cooling header 6 forward and backward toward the steel pipe 1 using the distance adjusting fluid pressure cylinder 25.

In addition, the radiation and amount from the external auxiliary cooling header 3 is determined by taking into account the cooling intensity received from the quenching tank liquid 2 according to the outer diameter of the steel pipe, the wall thickness, the number of rotations, and the conveyance speed, and the temperature difference around the steel pipe. P] by the water amount control pulp 23 to prevent the occurrence of
W is done.

The more the number of external auxiliary cooling headers 3 installed, the easier it is to average the temperature around the steel pipe, but the number of external auxiliary cooling headers 3 installed is determined depending on the quality of the steel pipe after external quenching and the processing conditions. Ru. Further, the number of nozzles 11 attached to the external auxiliary cooling header 3 is also determined according to processing conditions.

Furthermore, it is preferable that the distance of the nozzle 11 of the outer auxiliary cooling header 3 to the outer surface of the steel pipe be adjusted as described above, depending on the processing conditions, and the outer auxiliary cooling header 3 may be rotated to Nozzle 11 for 1
It is preferable that the angle of the angle can be adjusted.

3 and 4 show a second embodiment in which the present invention is applied to a vertically descending type external hardening method, in which a piston rod 29 of a hydraulic cylinder 28 for raising and lowering a plurality of support frames is shown.
is fixed to the lower part of the support frame 30, and a pair of horizontal rotating shafts 12 are installed at the lower part of the support frame 30,
A large number of turning rows 26 are fixed to each rotating shaft 12 at intervals, and the upper V? :, a plurality of hydraulic cylinders 31 for lifting and lowering the presser members are fixed, the piston rod 32 of each hydraulic cylinder 31 is connected to a presser member 33, and a plurality of hydraulic cylinders 31 are connected to a pair of horizontal rotating shafts 34 installed on the presser member 33. Clamp rolls 7 are fixed at intervals, and a plurality of inclined distance adjustment fluid pressure cylinders are attached to the external auxiliary cooling header 3, which is arranged to face the clamp rolls 7 of a pair of rotating shafts 34, respectively. The piston rod 27 at 25 is connected, the cylinder at the fluid pressure cylinder 25 is fixed to a support stand 35, the support stand 35 is fixed to the cross beam 24 which is fixed to the support frame 30, and is placed on the turning row 26. The distance between the outer surface of #v7 and the nozzle 13 of the outer auxiliary cooling header 3 is adjusted by moving the outer auxiliary cooling header 3 back and forth toward the steel pipe 1 using the distance adjusting fluid pressure cylinder 25.

! As shown in FIG. 3, the heated steel pipe 1 is guided by the skid rail 4 and conveyed and placed on each turning roller 6, and then is moved to a hydraulic cylinder 31 for lifting and lowering the presser member.
The holding member 36 and each clamp roll 7 are lowered by the extension operation, and the clamp roller lure is pressed against the upper surface of the copper pipe 1, and the steel pipe 1 is held by each of the turning rollers 6 and each clamp roll 7. While the steel pipe 1 is being rotated via the rotation shaft 12 and the turning roller 6, the support frame 30 and each support frame supported by it are The parts are lowered vertically.

As shown in FIG. 4, at the moment when the steel pipe 1 comes into contact with the quenching bath liquid 2, or immediately before or after that, the quenching cooling liquid is poured into the steel pipe 1 from the nozzle 11 of each external auxiliary cooling header 3. The liquid is sprayed onto the outer surface of the liquid part, and in this state the support frame 3
0 and each part supported by it continues to vertically descend, and the steel pipe 1 is immersed in the quenching tank liquid 2, and its g4
The tube 1 is externally hardened.

After finishing the external hardening of the steel pipe 7, the support frame 30 and the parts supported by it are moved upward by the extension operation of the hydraulic cylinder 28 for lifting and lowering the support frame, and then the hydraulic cylinder for lifting and lowering the presser member is moved upwardly. 3
After the clamp roll 7 is moved upward via the presser member 63 by the shortening operation 1, the hardened steel pipe on the turning roller 6 is carried out.

Next, a specific example in which the present invention is implemented to harden the outer surface of a steel pipe will be described.

Outer diameter 244.5 mm, wall thickness 11.99 sections, length 1270 mm
After heat-treating the steel pipe at 850°C, the steel pipe at station 0 is transferred 1.3m/1.3m to the inclined transfer type hardening equipment shown in Figures 1 and 2.
At the same time as the steel pipe 1 is brought into contact with the quenching tank liquid 2, the cooling liquid is injected from the nozzles 11 of the three rows of external auxiliary cooling headers 3 onto the outer surface of the non-fluid part of the steel pipe. The steel pipe was immersed in the quenching bath liquid 2, and the outer surface of the steel pipe was quenched. Further, the nozzle 11 in the external auxiliary cooling header 3 was set at 70 vn, D12-1/min per nozzle water tt-1, and injection time at 1 second.

As a comparative example, steel pipes of the same size were heat-treated under the same temperature conditions, then transported at the same transport speed to an inclined rolling conveyance type hardening device without an external auxiliary cooling header, and immersed in the hardening bath liquid. Then, the outer surface of the steel pipe was hardened.

As a result, in the case of the comparative example, the out-of-roundness after quenching was approximately 2
However, in the case of the embodiment of the present invention using an external auxiliary cooling header, the out-of-roundness was only about 7%, and the hardening quality was extremely good.

When implementing the invention, the hydraulic cylinder 25.2
8.31.36 may be either a pneumatic cylinder or a hydraulic cylinder.

〔Effect of the invention〕

According to this invention, when the heated #4 pipe 1 is conveyed and immersed in the quenching bath liquid 2 to be quenched and cooled, when the heated steel pipe 1 comes into contact with the quenching bath liquid 2, the external surface auxiliary Since the cooling liquid for quenching is injected from the cooling header 6 onto the non-liquid outer surface of the steel pipe 1, the degree of quenching on the outer surface of the steel pipe can be made uniform over the entire circumferential direction by a simple means, and therefore stable. In addition to enabling high-temperature quenching operations, the external quenching quality has been significantly improved.

[Brief explanation of the drawing]

FIG. 1 is a schematic longitudinal sectional front view for explaining the method of the first embodiment of the present invention, and FIG. 2 is a perspective view showing a part of FIG. 1. 3 and 4 are schematic longitudinal sectional front views for explaining the method of the second embodiment of the present invention, and FIG. 6 shows a steel pipe placed on a pair of turning rolls above the quenching bath liquid. FIG. 4 is a schematic longitudinal sectional front view showing a state in which the lower part of the steel pipe is immersed in the quenching phase liquid. FIG. 75 is a schematic longitudinal sectional front view for explaining a conventional steel pipe quenching method. In the figure, 1 is the steel pipe, 2 is the quenching tank liquid, and 6 is the outer surface? it
? auxiliary cooling header, 5 is a quenching tank, 6 is a turning roller, 7 is a clamp roll, 8 is a charging skid, 9 is a chain conveyor with a charging dog, 10 is a dog, 11 is a nozzle, 72 is an exciting shaft, 16 is a rod, 14 is a support arm,
75 is a chain conveyor with a dog for carrying out, 16 is a dog, 77 is a carrying skid, 19 is a position detection sensor, 22
is electric, -* I+, i-Q CJ-+
Re Me flW Ti? PR8;
B: , V/ I+ ・-j"l"
) 0 is a fluid pressure cylinder for raising and lowering the support frame, 30 is a support 7 frame, 31 is a fluid pressure cylinder for raising and lowering the holding member,
33 is a holding member, and 36 is a fluid pressure cylinder for moving the roll.

Claims (1)

[Claims] When the heated steel pipe 1 is conveyed and immersed in the quenching bath liquid 2 for quenching cooling, when the heated steel pipe 1 comes into contact with the quenching bath liquid 2, cooling for quenching is applied from the external auxiliary cooling header 3. Pour the liquid into steel pipe 1
A method for quenching the outer surface of a steel pipe, characterized by injecting liquid onto the outer surface of the pipe.