JPS61193718A - Descaling device of steel pipe - Google Patents

Abstract

PURPOSE:To prevent the approach of descaling water into the inner face of a steel pipe and to improve the quality with performing descaling by arranging plural nozzle tips on the inner periphery of the header forming the through space of the steel pipe on the center, by providing at least two pieces line at the prescribed intervals in the steel pipe progressing direction, also by arranging the jet port of the nozzle tip directed for reverse direction each other. CONSTITUTION:A front stage nozzle header A is provided on one part side where the jet of descaling water 5 is directed in the progress direction of a steel pipe 1 and a rear stage nozzle header B on the other part which is directed reversely to the progressing direction of the steel pipe 1 and until before the rear end of the steel pipe passing through the front stage nozzle header A, it is jetted only from the front stage nozzle header A and the jet of the front stage nozzle header A is stopped before the rear end of the steel pipe 1 passing through the front stage nozzle header A and simultaneously the rear stage nozzle header B is jetted and the descaling is performed without the approach of water to the inner part of the steel pipe.

Description

[Detailed Description of the Invention] (Industrial Application Field) This invention relates to a descaling device for a hot steel pipe immediately after being heated and extracted from a furnace for the rolling process or heat treatment process of the steel pipe. .

(Prior Art and Problems) In recent years, with the increasing demand for higher quality seamless steel pipes, the proportion of heat treatment such as quenching or thermal refining has gradually increased. If a steel pipe becomes bent during the quenching or heat refining process, it may cause trouble during transportation and handling after leaving the quenching or heat refining equipment, etc., or it may lead to quality problems such as poor straightness. . In addition, poor roundness caused by hardening has a significant negative impact on product quality.

Causes of so-called "quenching distortion" such as bending and poor roundness of steel pipes due to quenching include skid marks during furnace heating, and nozzles in the unevenly heated water cooling zone due to differences in heating conditions between the upper and lower parts of the steel pipe. Possible causes include uneven cooling due to deviations in flow rate and pressure, and uneven thickness of the steel pipe during rolling, but the most important causes are mill scale and scale that forms and adheres to the surface of the steel pipe in the heating furnace. A scale-free steel pipe surface has a high heat transfer coefficient and a high hardening ability, but on the other hand, a steel pipe surface with scale adhesion has a significantly poor heat transfer coefficient. Steel pipes that receive strong cold from the outside have less heat transfer in the circumferential direction than in the thickness direction, so if parts without scale and parts with scale adhere to the same steel pipe surface coexist, the parts without scale will It is rapidly cooled down to the inside. On the other hand, the part where the scale is attached is cooled relatively slowly until it reaches a circular surface. This time lag in temperature drop inside the steel pipe results in a time lag in transformation expansion due to martensitic transformation, resulting in total residual strain, resulting in bending and poor roundness of the steel pipe.

Conventionally, the water jet from the header that descales the outer surface of the steel pipe immediately after it has been extracted from the heating furnace for the rolling or heat treatment process has been sprayed at an angle of about 156 in the direction of travel with respect to the axial center of the steel pipe. If this is not done, immediately after the rear end of the steel pipe passes through the header, desk water will enter the inside of the steel pipe from the rear end, causing uneven cooling and causing bending. In addition, in order to prevent this, there is a method in which the jetting of water is fully started before the tip of the steel pipe enters the header, and the jetting of water is stopped immediately after the rear end of the steel pipe passes the header. Odor 1 Due to irregularities in the operating accuracy of the water on-off valve,
If the closing action is too fast, a gap may be left at the end of the steel pipe.
If the closing action is slow, water will infiltrate inside the steel pipe, which will have a significant negative impact on quality such as bending, poor roundness, and outer surface skin during the subsequent heat treatment process.

(Means and effects for solving the problem) In order to solve the above-mentioned problems, the present invention includes a nozzle on one side, that is, a front stage nozzle, where desk water is jetted in the direction of movement of the steel pipe;
Install a rear nozzle on the other side facing opposite to the traveling direction of the steel pipe, and inject only the front nozzle until the rear end of the steel pipe passes through the front nozzle. At the same time as all nozzles stop, the downstream nozzle is activated to descale the steel pipe without water entering the pipe. Accordingly, in the present invention, each header in the front stage and the rear stage may be composed of two or more sets, and each header may be divided into a front stage and a rear stage, and the injection ports of the nozzle tips may be arranged in opposite directions. It is possible.

(Embodiment) A detailed explanation will be given below based on an embodiment device provided with two total headers of the present invention.

FIG. 1 shows a piping system diagram of an apparatus according to an embodiment of the present invention. The inlet nozzle header A and the outlet nozzle header B have injection valves 7 and 8, respectively, and can independently inject and stop the water injection. Incidentally, the supply of water to the headers A and B is performed by a pump IO.

FIG. 2 is a front view of the apparatus according to the embodiment of the present invention, and FIG. 3 is a side view of the same. The steel pipe 1 is conveyed while being supported by conveyance rollers 2. Between the arrangement of the conveyor rollers 2, a header frame 3 is installed, which has a circular nozzle header A for descaling the tip to the rear of the steel pipe 1, and a circular nozzle header Bi for descaling only the rear end of the steel pipe 1. There is. The nozzle headers A and B are arranged on the circumference of several nozzle chips f4'lk that uniformly inject desk water all over the circumference of the steel pipe 1. Further, the desuke water 5 is supplied from a connecting pipe 6 to the nozzle header.

FIG. 4 shows a side cross-sectional view of the nozzle headers A and B in a state where the entire rear portion of the steel pipe 1 is descaled from the tip. FIG. 5 shows the nozzle header A with the rear end of the steel pipe 1 being descaled.

A side sectional view of B is shown. From the tip to the rear of the steel pipe 1, operate Dar-A to the nozzle that injects the desk water 5 in the direction of movement of the steel pipe 1, and inject the desk water 5 in the opposite direction to the direction of movement of the steel pipe 1. The nozzle header B is in a stopped state. In addition, the rear end of the steel pipe l is connected to the nozzle header A.
At the same time as the nozzle header B is stopped, the nozzle header B is operated. This operation is performed by opening and closing the injection valves 7 and 8 installed in the intermediate piping between the pump 10 and the nozzle hoses A and B in response to signals from the tip and rear end detectors 9 of the steel pipe 1. Prevents water from entering the inner surface. When arranging two or three front and rear headers, the two or three nozzle chips on one side face in the same direction, and the two or three nozzle chips on the other side face in the opposite direction. It is also possible to arrange them all at once.

(Effects of the Invention) As described above, if the present invention is used, there will be no intrusion of water into the inner surface of the hot steel pipe immediately after it has been heated for the rolling process or heat treatment process, thereby preventing bending of the steel pipe. Poor roundness, etc. are likely to occur. Therefore, transportation and handling in post-processing is easy. Furthermore, since reliable descaling can be performed from the tip to the rear end of the steel pipe, it is very effective in improving the quality of the outer surface of the steel pipe.

[Brief explanation of drawings]

Fig. 1 is a piping system diagram of the apparatus according to the embodiment of the present invention, Fig. 2 is a front view of the apparatus according to the embodiment of the present invention, and Fig. 3 is a side view of the apparatus.
4 and 5 are side sectional views of the header of the apparatus according to the present invention. l... Steel pipe, 2... Conveyance roller, 3...
...Header mount, 4...Nozzle tag, 5...
Desuke water, 6... Connection pipe, 7.8... Injection valve, 9... Steel pipe detector, 10... Pump,
A, B... Nozzle header. Figure 3 Figure 4 A, is Ni Nosuru - No Yuichi

Claims (1)

[Claims] A plurality of nozzle chips are arranged on the inner periphery of a header that has a passage space for the steel pipe in the center, and at least two of the headers are arranged in rows at a predetermined interval in the direction of movement of the steel pipe, and the header is arranged on the inner periphery of the header. A steel pipe descaling device characterized in that the injection port of a nozzle tip on one side and the injection port on the other side are arranged in opposite directions.