JPH08174041A - Method for controlling cooling water in production of hot welded pipe - Google Patents

Abstract

PURPOSE: To stabilize the product quality at the time of acceleration and deceleration of a production line by measuring a production line speed and controlling the cooling water volume of a pipe weld part and pipe making rolls and rolling rolls in accordance with this production line speed. CONSTITUTION: The actual optimum values according to the line speeds are used for the adequate cooling water volume according to the respective production lines of an instrument 6 for measuring the production line speed from the number of revolutions of the pipe making rolls 2 revolving while maintaining contact with the pipe, an arithmetic unit 7 for calculating the adequate cooling water volume by calculating the speed data obtd. from this production line speed measuring instrument 6, a controller for the cooling water volume of the pipe weld zone for executing the correct control of the adequate cooling water calculated by this arithmetic unit 8, a controller 9 for the cooling water volume of the pipe making rolls and a controller 10 for the cooling water volume of the rolling rolls. The setting of the inflection point where the proportional constant of the line speed and the cooling water volume changes at arbitrary positions at plural points is, therefore, made possible in order to control the adequate cooling water volume with a high accuracy.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cooling water control method in manufacturing hot welded pipes.

[0002]

2. Description of the Related Art A conventional method for producing a hot welded pipe is as shown in FIG. 3, in which a strip steel 1 is produced into a pipe by a hot pipe making machine, and a predetermined rolling machine as shown in FIG. After rolling to the outside diameter and pipe thickness, the product is cut into a specified length.

Among the hot pipe cooling during this manufacturing process, 1) the cooling water for cooling the welded portion 5 of the pipe 2) the cooling water for cooling the pipe making roll 2 and the rolling roll 3 is the production line speed. Constant (that is, at constant speed)
Outputs a constant amount of water.

Since the cooling water for cooling the welded portion of the pipe of 1) has a great influence on the welding condition of the welded portion of the pipe, for example, the flatness, the bead height of the welded portion and the like, the production line. When accelerating or decelerating the speed of, it is necessary to adjust the amount of cooling water as needed. Also, regarding the roll cooling water in 2), it is necessary to make the amount of cooling water appropriate when the production line speed is greatly accelerated or decelerated.

A conventional cooling technique for welded pipes is disclosed in Japanese Patent Application Laid-Open No. 1-78623 and a method for controlling the amount of cooling water for the entire pipe according to the line speed for preventing bending of the pipe, and Japanese Patent Application Laid-Open No. 2-305924. No.
There is a method of measuring the temperature of the welded portion of the ERW pipe and performing feedback control of the cooling water of the welded portion.

[0006]

However, in the method disclosed in JP-A-2-305924, in order to control 1) the amount of cooling water in the welded portion, 2) the amount of cooling water in the pipe making roll and the rolling roll. , Controlling the amount of cooling water in the weld while measuring the temperature in the weld
It is difficult due to harsh conditions such as scale, and considering the environment in which it is used, its durability is also unreliable, and there is a problem in actually controlling it for a long period of time.

Under the circumstances, in the control of the cooling water in the above 1) and 2), the amount of the cooling water is appropriately adjusted manually at the time of accelerating and decelerating the production line speed. Therefore, it is not possible to cope with the situation where the line speed changes frequently, and it is not possible to control the amount of cooling water appropriately. For this reason,
This is a cause of troubles in product quality such as deterioration of welding quality during acceleration and deceleration.

Conventionally, the cooling water amount of the pipe welded portion and various rolls was appropriately adjusted while measuring the state of the product at the time of accelerating or decelerating the production line speed because of its importance to the product quality. When the line speed was frequently accelerated or decelerated, the operation could not be handled, which was a factor in product quality problems.

Therefore, it is necessary to control the amount of each cooling water by a simpler method instead of such a difficult method.

Further, the above-mentioned JP-A-1-78 shown in FIG.
In the cooling device for preventing the bending of the pipe disclosed in Japanese Patent No. 623, the pipe that has passed through the molding machine including the pipe-making roll and the rolling roll is controlled by the signals of the production line speed measuring device 6 and the thermometer 54. It is a method of controlling the amount of water in the cooler 55 by the flow rate control valve 52 as compared with the set value, and controlling the amount of cooling water in the entire pipe according to the production line speed.
In processes that are important for product quality such as cooling of welded parts, it is not possible to deal with the method of the above-mentioned publication in which the amount of each cooling water changes linearly at a constant rate according to the line speed, and more detailed control is possible. Is required.

The problem to be solved by the present invention has been
Acceleration of the production line by automatically adjusting the cooling water of the pipe welding part, pipe making roll, and rolling roll to the optimum amount according to the production line speed, which had to be adjusted when accelerating and decelerating the production line. , To stabilize product quality during deceleration.

[0012]

[Means for Solving the Problems] The above problem is to measure the production line speed in the process of producing a hot welded pipe and control the amount of cooling water for the pipe welded portion, the pipe making roll and the rolling roll based on this production line speed. This is solved by a cooling water control method in the production of hot welded pipes.

[0013]

The required cooling water amount is automatically calculated by inputting the speed data obtained from the device for accurately measuring the manufacturing line speed into the proper cooling water amount calculation device for converting the speed data into the appropriate cooling water amount according to the manufacturing line speed. , Is output to a device that opens and closes the motorized valve of the cooling water. As a result, the proper amount of water can be automatically adjusted according to the production line speed.

[0014]

Embodiments of the present invention will be described with reference to the schematic plan view shown in FIG. In FIG. 1, a device 6 that measures the production line speed from the number of revolutions of a pipe making roll that rotates while making contact with the pipe, and speed data obtained from the production line speed measuring device 6 are calculated to calculate an appropriate amount of cooling water. The speed of each manufacturing line of the arithmetic unit 7, the pipe welding portion cooling water amount control device 8, the pipe roll cooling water amount control device 9, and the rolling roll cooling water amount control device 10 for accurately controlling the proper cooling water calculated by the arithmetic device For the appropriate cooling water amount, the optimum value based on the actual results according to the line speed is used, and in order to control the appropriate cooling water amount more accurately, multiple inflection points at which the proportional constant of the line speed and the cooling water amount changes can be set arbitrarily. It can be set to the position.

The arithmetic expression of the cooling water amount control of the present invention is obtained by setting the cooling water amount corresponding to an arbitrary plurality of line speeds and connecting the plural points as shown in the graph of FIG. It was a set of straight lines. Therefore, it is possible to cope with a change in line speed. Further, an inflection point at which the proportional constant of the cooling water amount corresponding to the line speed changes can be set, and a wide range of changes in the manufacturing line speed can be accommodated. However, if the amount of cooling water changes frequently with a slight change in the manufacturing line speed, the product quality becomes unstable. Therefore, it is possible to set the dead zone so that the amount of cooling water does not change even if the manufacturing line speed changes slightly.

For example, as shown in FIG. 2, when the production line speed is in the vicinity of 0 to 20 (m / min), the cooling water electric valve opening is set to the production line speed in the range of 0 to 40 (%). Proportional control, while the production line speed is in the vicinity of 20 to 60 (m / min), proportional control to the production line speed is 20 to 60 (m / min) while the cooling water electric valve opening is 40 to 50 (%). While the manufacturing line speed is in the vicinity of 60 to 80 (m / min), the cooling water electric valve opening is controlled to 60 to 80 (%) in proportion to the manufacturing line speed. 80-1
During the vicinity of 00 (m / min), the cooling water electric valve opening is set to 8
The control method is such that 0 (%) is constant. In addition, at each line speed, the dead zone can be set at all line speeds so that the cooling water amount does not change even if the manufacturing line speed changes minutely. For example, line speed 0 to 50m
In the range of / min, the amount of cooling water should not change when the line speed changes within ± 2 m / min.

[0017]

According to the method for controlling the amount of cooling water in the production of hot welded pipes according to the present invention, the optimum amount is adjusted according to the acceleration and deceleration of the production line speed, so that the product quality of the pipe can be stabilized. Became.

[Brief description of drawings]

FIG. 1 is a diagram showing an arrangement of a production line and various cooling water amount devices.

FIG. 2 is a diagram showing an example of a relationship between a production line speed and a cooling water electric valve opening degree.

FIG. 3 is a plan view (a) showing an outline of the production line and a tube sectional view (b) showing a cooling position.

FIG. 4 is a cooling control diagram in the related art.

[Explanation of symbols]

 1 Strip Steel 2 Pipe Rolling Roll 3 Rolling Roll 4 Pipe Cross Section 5 Welding Section 6 Manufacturing Line Velocity Measuring Device 7 Calculation Device for Calculating Appropriate Cooling Water Volume 8 Pipe Welding Zone Cooling Water Volume Control Device 9 Pipe Rolling Water Cooling Volume Control Device 10 Rolling Roll cooling water amount control device 11 Formed steel pipe 12 Hot saw 51 Pump 52 Flow rate control valve 53 Control device 54 Thermometer 55 Cooler

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Internal reference number FI Technical indication B21B 37/78 (72) Inventor Yukihiro Ikeda 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Nippon Steel Tube Co., Ltd. (72) Inventor Yuji Sugimoto 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Nihon Steel Pipe Co., Ltd.

Claims (1)

[Claims] 1. A hot-welding pipe characterized in that, in a manufacturing process of a hot-welded pipe, a production line speed is measured, and the amount of cooling water of a pipe welding portion and pipe-making rolls and rolling rolls is controlled based on the production line speed. Cooling water control method in welded pipe manufacturing.