JPS5938331A - Immersion hardening method of steel pipe - Google Patents

Abstract

PURPOSE:To harden uniformly and evenly a heated steel pipe by holding the steel pipe with rotating and driving rolls and press rolls, rotating the rotating and driving rolls forward and backward to bring down the pipe and to immerse the same into water, injecting high pressure water simultaneously to the inside and outside surface of the steel pipe and discharging the pipe to the outside of the water surface with a discharging device. CONSTITUTION:A heated steel pipe 1 from a feed skid 4 is carried between rotating and driving rolls 9, and is pressed from above with press rolls 8. The pipe 1 is rotated by the rotation of the rolls 9 around the axial center thereof. The pipe 1 turns together with upper and lower arms 7a, 7b and an injection nozzle for high pressure water while rotating around the axial center thereof and is immersed in the cooling water in a water tank 11. The cooling water is injected to the inside circumferential surface of the pipe 1 from the injection nozzle for high pressure water and toward the outside surface thereof from a header 13 for the outside surface when the pipe 1 is immersed in the water. The pipe is delivered onto a receiving arm 14, and the arm 14 is turned to the position of a broken line where the pipe 1 is dropped onto a skid 21 and is discharged to the outside of the water surface with a conveyor 15.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an immersion hardening method that can uniformly harden the entire length of a pipe without causing scratches.

One of the ways to make steel pipes high in tension and toughness is to use quenching and tempering treatments, similar to other steel products. BACKGROUND ART Conventionally, as a method for quenching steel pipes, a method of quenching a heated steel pipe by immersing it in water has been known. In this case, it is necessary to uniformly harden the inner and outer surfaces of the steel pipe, so if the entire steel pipe is simply immersed in cooling water, the surface of the steel pipe will be covered with a vapor film produced by the boiling of the cooling water, and the pipe will be hardened. The cooling rate becomes slower than the critical cooling rate for martensitic transformation, which is necessary for normal quenching, and the quenching effect cannot be obtained. In order to remove this steam film, an additional operation is performed in which high pressure water is injected onto the inner and outer surfaces of the steel pipe.

However, in conventional immersion hardening equipment, it is difficult to align the center of the steel pipe placed in the water tank with the inner cooling nozzle, and it takes time. Furthermore, in the past, since the heated steel pipe was directly dropped into the water from above the water tank, there was a risk that the steel pipe would hit the bottom of the water tank or a support in the tank, causing damage to the outside surface of the steel pipe. In order to avoid this, even if the steel pipe is slowly immersed in water while being held by some kind of gripping device, the lower part of the steel pipe will be cooled first, causing uneven heating and sagging.

Since the steel pipe is heated before quenching, there is also the problem that the outer surface of the steel pipe may be damaged if it is held loosely.

In order to solve this problem, the applicant of the present application holds a heated steel pipe from above and below and lowers it while rotating in the air, and at the same time, the steel pipe is immersed in water, and at the same time, high-pressure water is applied to the inner and outer surfaces of the steel pipe. We have developed an immersion hardening method in which the steel pipe is injected into the water, and then transferred to a delivery device under water to be transported out of the water. The steel pipe is held between press rollers that are close to each other, and the steel pipe is rotated by the rotation of the rotary drive rollers. With this method, the steel pipe is not dropped as much as in the past, so damage can be prevented, and since it is immersed in water while being rotated from the air, uneven heating and the like do not occur. However, the portions of the rotary drive rollers and presser rollers that support the steel tube that are in contact with the outer surface of the steel tube have a lower degree of contact with cooling water than other parts, which causes uneven heating.

The present invention has been made to deal with this problem by reversing the rotary drive roller that supports the steel pipe and forcibly changing the contact position of the roller in the forward and reverse directions along the pipe axis. An object of the present invention is to provide an immersion hardening method that does not cause uneven heating of steel pipes.

Hereinafter, the present invention will be explained by way of example with reference to the drawings.

FIG. 1 is a cross-sectional view of a main part of an immersion hardening apparatus that is used to put the present invention into practice. Note that this figure was cut along a plane perpendicular to the longitudinal direction of the steel pipe set for hardening. First, the part that supplies the steel pipe to this immersion hardening apparatus will be briefly explained. The heated steel pipe 1 is conveyed by V-shaped conveyance rollers 2 along a conveyance line in the longitudinal direction (direction perpendicular to the plane of the drawing) and is stopped at the side of the quenching device. A carry-in skid 4 and a stepping arm 3 are provided on the side of the hardening device between the hardening device and the conveying line.

The steel pipe 1 on the conveying roller 2 is scooped out onto the carry-in skid 4 by the stepping arm 3, rolls on this, and is placed on the rotary drive roller 9 of the steel pipe holding device according to the present invention.

The steel pipe holding device includes a set of rotary drive rollers 9 that are close to each other, a set of presser rollers 8 that are close to each other, a drive device for the rotary drive rollers 9 (not shown), and a pressing drive device for the presser rollers 8 (not shown). Apparatus)】6. The rotation drive roller 9 is pivotally supported at the tip of the lower arm 7a of the tilting device.
The driving device repeats normal rotation, stop, and reverse operation at a predetermined period. The presser roller 8 is rotatably supported at the tip of a piston rod 17 of a cylinder device 16.

The cylinder device 16 is fixed to the tip of the upper arm 7b of the tilting device. Upper and lower arms 7a of the tilting device.

7b is fixed to the rotating shaft 6. The rotating shaft 6 is pivotally supported by the pedestal 5, and an electric motor (not shown) is provided outside the water tank 11.
It is designed to be reversibly rotated (reciprocating rotation) within a predetermined angular range. Further, a stepping arm 10 as shown is attached to the lower arm 7a. like this'
A plurality of 41 pipe holding devices and tilting devices are provided at appropriate intervals along the longitudinal direction of the steel pipe. A high-pressure water injection nozzle is fixed to the shaft end of the rotating shaft 6 of the tilting device and is aligned so that it is aligned with the steel pipe 1 on the rotary drive roller 9. Note that the high-pressure water injection nozzle does not appear in the cross-sectional position of this drawing.

A water tank 11 is disposed below the fil a holding device @h and the tilting device. Inside the water tank 11, a receiver having a concave steel pipe receiving portion is pivotally supported so that the arm 14 can rotate within a predetermined angular range. Further, a circulating type conveyor device is provided, the entire lower half of which is immersed in the water of the water tank, and only the -L portion thereof protrudes diagonally toward F from the water surface 18. This conveyor device is
For example, an endless chain 20 is wound around sprockets at both ends, and a plurality of steel pipe receiving hooks 19 (1i/if) are attached to the outer surface of the chain at predetermined intervals. The endless chain 20 rotates in the direction of the arrow shown by the rotation of the tit sprocket. Near the end of the conveyor device,
An aerial conveyor car for quenched steel pipes is installed.

The receiver is between the arm 14 and the conveyor device 15 and σ (29,
The receiver is provided with an underwater skit 21 for rolling the steel pipe discharged from the arm 14 and passing it to the conveyor device 15. The rotary driving roller 9 supported by the lower arm 7al of the tilting device is at the empty position shown in the figure when the steel pipe that has been rolling on the skid 4 is taken up, and from this position the rotating shaft is rotated. The first part of 6 is rotated in the direction of arrow A (21 m U L CtJ< 2 1 m U L CtJ < 2 IJ with the axis of rotation as the center, the receiver stops near the upper limit position LL of the arm 14, and by forward and reverse rotation of the rotating shaft 6 In the aquarium, along the moving path of the rotating roller 9 and on both sides (the header 13 on the outer surface 1 is opened. High aqua regia is sprayed towards the outer surface of the steel pipe in the water.

The immersion hardening apparatus configured as described above (the operation of gluing 2-1J steel pipes will be explained).
When the steel pipe 1 that has been rolling on the upper side is supported between the rotating claw bell h rollers 9, the steel pipe 1 is pushed from the cylinder device (therefore the presser roller 8 exerts an upward force) , these rollers 9 and 8 exert a pressing force (4 and 10) on the f4 pipe l.
(approximately 1 Kg) is used to skewer the #1 scraps l + il on a net by the rotation of the drive wheel J and roller q around the axis. At this point, the rotating shaft 6 rotates, and the steel 'i
l 11 While rotating around its own @3 center, the upper and lower arms 7b, 7a and the high-pressure water injection nozzle and a) I-1τ
The stone is immersed in the cooling water of the water tank by turning 1 rotation axis 6 cy'' + rotation number. The water is hydraulically injected towards the inner curve of the pipe W4, and water is also injected from the header 13 of the steel pipe towards the outer surface of the steel pipe.
3 is 1+1 when the outer surface of the steel pipe is cooled. ′; is near 1
(Has the effect of stirring 1 liter of water. Steel pipe 1 liter of water [1 liter)
] When quenched by immersion in the water, the pressing force of the presser roller 8 in the water is stronger than in the air;
It will be about 0K9. When the rotation 1 drive roller 9 comes close to the car receiver C1 arm 14, the presser roller 8 force; rises and presses If force? "Release""F arm 7a + = set (Sta jump 1B arm lO operates, W on rotation drive roller 9
Kick out the 4 pipes 1 from below and attach the receiver to the 4 parts (1) of the arm 14.
Pass the uke. After the steel pipe 1 is transferred to the receiving arm 14, the rotating shaft 6 rotates in the opposite direction, and the upper and lower arms 7b and 7a return to their original positions. In response to this, the arm 14 rotates to the position shown by the broken line in the figure, and as a result, the Fl pipe is moved by its own weight to the underwater skid 2.
1 and rolls on this to be picked up by the receiving hook 19 of the conveyor device 15. The receiving arm 14 returns to the upper limit position, and the hardened steel pipe held on the conveyor device 15 is carried out of the tank from the north end of the conveyor device 15. Note that the operation timing of each member of the device is automatically determined by timer settings and the like.

According to one embodiment of the present invention, the steel pipe 1 is actively rotated and moved in a helical manner according to the rotation direction of the drive roller 9, thereby causing the steel pipe 1 to move back and forth in the longitudinal direction. FIG. 2 is a schematic front view showing a steel pipe holding device for carrying out this embodiment.

The plurality of rotary drive rollers 9 are all mounted in a horizontal plane with their center axes 9a 7-1 relative to the roller drive shaft 25 and slightly inclined in one direction. When the rotary drive roller 9 rotates in the forward direction, the steel pipe 1 moves a distance to the right in the figure and reaches the state 1', and when the roller 9 rotates in the opposite direction by the same amount, the steel pipe 1 moves to the left ( (in the opposite direction) by the same distance, and by repeating the forward and reverse rotation of the roller 9, the net vt moves back and forth between the distances. Due to this reciprocating movement of the steel pipe,
This prevents the rotary drive roller 9 and the presser roller 8 from contacting only the same part of the outer surface of (11'q1), making uniform hardening possible. Note that the steel pipe 1 is moved back and forth by forward and reverse rotation of the roller 9. is not limited to the above-mentioned aspects,
Of course, other means may also be used, such as using a ball roller as the rotary drive roller.

According to the present invention, a plurality of locations in the longitudinal direction of 1M steel are inserted into water from the air in a rotating state while being held between two sets of four rollers, upper and lower at each location, and the receiver is connected to the arm from the holding device. The steel pipes are transferred very close to the swash plate, swash plate, and conveyor device, so if the fi4W were to fall from a high position underwater and get scratched, it would be a heat adjustment problem. After immersion, the steel pipe is moved back and forth in the axial direction by forward and reverse rotation, and high-pressure water is sprayed on the inner and outer surfaces of the pipe, thereby making it possible to harden uniformly and without any unevenness. When the pipe is heated in the air, it is held down lightly, and when it is submerged in water for quenching, the holding pressure on the steel pipe is increased, which also prevents the steel pipe from being damaged or bent. . Further, in the hardening apparatus of the present invention, automation of the process from carrying in to carrying out the steel pipe can be easily performed by timer control.

[Brief explanation of drawings]

FIG. 1 is a schematic groove sectional view of a steel pipe hardening device used to carry out the present invention, and FIG. 2 is a schematic front view 1-4 of the steel pipe holding device according to the present invention. 1...Steel pipe, 4...1 general skid, 6...rotating shaft,
7a...lower arm, 7b...upper arm, 8...press roller, 9...rotation drive roller, 11...water tank, 1
4...Receiver is arm, 15...Conveyor device, 16.
...Cylinder device, 21...Underwater skid, 9a...
・Rotation drive roller axis. Agent: Attorney Toshiyoshi Somekawa

Claims (2)

[Claims] (1) While holding the heated steel pipe from above and below, lower it while rotating in nitrogen, and at the same time as the mesh pipe is immersed in water, high aqua regia is injected onto the inner and outer surfaces of the steel pipe, and then immersed in water. In an immersion hardening method for steel pipes in which a receiver is passed to a carry-out device and carried out of the water surface, the steel pipe is held between a rotary drive roller and a presser lobe, and during this holding, the rotary drive rollers are rotated in forward and reverse directions. A distinctive method of immersion hardening for steel pipes. (2) The method of immersion hardening a steel pipe according to claim 1, wherein the steel pipe is reciprocated in the longitudinal direction according to the rotation direction of the rotary drive roller.