JPS6322884B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for detecting uniform heating of a rod-shaped rolled material,
In particular, the present invention relates to a detection method suitable for use in a pipe manufacturing process. The progress in rolling technology in recent years, coupled with the introduction of computers, has been remarkable. In plate rolling, the introduction of thickness-changing rolling, completely continuous rolling, etc. has become a reality, and there is a tendency for almost complete automation to be realized. However, automation has not yet been achieved in tube rolling, which plays an equally important role in rolling as plate rolling, and production still continues to rely on the experience and intuition of experts. The reason why automation has not been achieved in the rolling of steel pipes, etc. is thought to be that rolling is more complex than that of steel plates, and as a result, there are many parts that have not yet been sufficiently analyzed theoretically.
Recently, automation using computers has begun to be considered in the pipe manufacturing process, and although calculations for setting up rolling mills have been realized in a small number of cases, other complex operations still rely on skilled workers. In this pipe-making process, what requires the experience and intuition of experts to the utmost is cutting the material into a pipe.
It is said to be a so-called drilling process. In this drilling, the problem is the variation in deformation resistance of each part of the material due to uneven temperature distribution of the material. If the deformation resistance is not uniform in each part of the material, a so-called uneven-walled pipe, in which the wall thickness of the pipe is not uniform, will be created during drilling. This uneven thickness that occurs during the drilling stage has a negative effect on the subsequent steps, and its correction leads to a decrease in productivity and a decrease in quality. Therefore, in the drilling work, it is important to select an appropriate tool, rolling speed (drilling speed),
This is why experiential know-how such as roll opening is important. However, the important point here is that uneven wall thickness pipes are caused by variations in the temperature distribution of the material. Even if a person is highly skilled and has a high level of skill, he or she may not be able to fully demonstrate his/her skills due to variations in material temperature, which is the cause of this problem. There is a limit. For this reason, conventionally, when uneven wall thickness pipes occur, the first step is to readjust the roll opening and rolling speed of the rolling mill for perforation, or to replace the piercer for perforation, and then Perform perforation of the next rolled material. If pipes with uneven thickness still occur, operations such as changing the control settings of the furnace to which the rolled material is supplied and adjusting the soaking time are repeated.
The problem with this conventional technology is that the roll opening degree and rolling speed of the rolling mill are readjusted only after the phenomenon of uneven wall thickness pipes occurs. Furthermore, since these adjustments are made ignoring the true cause of uneven wall thickness pipes, they do not provide an essential solution and have their own limitations. In addition, due to the repeated occurrence of pipes with uneven thickness, the soaking time of the rolled material in the furnace is adjusted, but although this is recognized to have some preventive effect against the occurrence of pipes with uneven thickness in the future, in reality Because the temperature variation of the rolled material, which is the biggest cause of this occurrence, is not measured, it is not possible to provide an appropriate soaking time. As a result, whether pipes with uneven thickness do not occur or not depends on the fact that the soaking time of the furnace is adjusted depending on the occurrence of the pipe with uneven thickness in the first place.
A problem arises in that the rolled material in the furnace, which has been soaked during the soaking time, is supplied to the rolling mill and cannot be determined unless the results of the perforations are seen. If uneven wall thickness pipes occur again, the soaking time is reset and the situation is monitored, so any rolled material extracted from the furnace during that time has the possibility of being perforated by the uneven wall pipes. . In the present invention, based on the recognition that variations in deformation resistance, which are a factor in the occurrence of uneven wall pipes, are mostly caused by variations in temperature at various parts of the rolled material,
We will focus on this temperature variation, that is, the soaking state of the rolled material. By understanding this uniform heating state,
Not only can the occurrence of pipes with uneven thickness in the pipe manufacturing process be almost completely predicted, but also the uniform heating state of the rolled material can be used to control the uniform heating of the rolled material. Therefore, an object of the present invention is to provide a method for detecting the soaking state of a rolled material. The present invention rotates the bar-shaped rolled material taken out from the furnace before supplying the rolled material to a piercing mill and forms it into a tubular shape, and a device is provided at the entry point of the rolled bar-shaped material. The output of the one or more temperature detectors is calculated from the rotational speed of the bar-shaped rolled material so that the interval between temperature measurement points in the circumferential direction of the surface of the bar-shaped rolled material is a preset interval. The method is characterized in that the uniform heating state of the bar-shaped rolled material in the circumferential direction is detected based on the distribution of the plurality of measured values taken in at certain time intervals.
Other objects and features of the invention will become apparent from the description below. Here, the circumferential direction of the rolled material refers to the direction of the circumference with respect to the advancing direction of perforation. The present invention will be explained in detail below using the drawings. First, the principle of the present invention will be explained. The rolled material is charged into a furnace, extracted from the furnace through a heating process and a soaking process, and then supplied to a rolling mill for perforation as shown in FIG. 1, for example. In FIG. 1, 1 is a piercer roll, 2 is a piercer, and 3 is a rolled material. A rolled material extracted from a furnace (not shown) advances toward the roll exit side while being rotated by a piercer roll 1, and is perforated by a piercer 2. As mentioned above, a pipe with uneven wall thickness occurs during such a drilling process. The cause of this uneven wall thickness pipe is closely related to the soaking state of the rolled material. To explain this in more detail, the cause of uneven wall thickness pipes is thought to be due to variations in deformation resistance at each part of the rolled material, but as is clear from the properties of metals, this deformation resistance is most affected by the temperature of the rolled material. You receive it. The present invention focuses on this point,
The temperature distribution in each part of the rolled material, that is, the state of uniform heating, is used as a parameter that causes uneven wall thickness in the pipe.
The soaking state can be recognized by measuring the temperature of each part of the rolled material and by the degree of variation. Specifically, this is to determine in which frame the difference temperature ΔT _M [℃] between the highest and lowest temperature values of each part falls within a frame divided into several stages in advance. This can be recognized as such, or the temperature difference ΔT _M can be used as is as the degree of uniform heating. Alternatively, all measured values may be averaged and the difference between the average value and each measured value may be used, or the difference may be recognized as the degree of dispersion. In short, the uniform heating state can be recognized by detecting temperatures at multiple points on the rolled material and comparing them in some way. However, what is important here is that it is not enough to simply measure the temperature at multiple points on the rolled material.
It should be noted that uneven wall thickness pipes often occur when the temperature in the cross section of the rolled material to be drilled is not uniform. Even if the degree of uniform heating in the longitudinal direction of the rolled material is poor, if the uniform temperature in the circumferential direction is good, uneven wall thickness of the pipe will hardly occur.
Therefore, even if the uniform heating state is detected in the longitudinal direction of the rolled material, the occurrence of uneven thickness cannot be accurately predicted. Therefore, in the present invention, the temperature is measured at a plurality of points not in the longitudinal direction of the rolled material but in the circumferential direction, and the soaking state is detected using the measured values. Of course, it goes without saying that if you repeat temperature measurements at multiple positions in the circumferential direction of the rolled material multiple times in the longitudinal direction of the rolled material, it is possible to detect a uniform heating state that is useful for predicting the occurrence of uneven wall thickness pipes. stomach. This is because there are generally variations in temperature both in the circumferential direction and in the longitudinal direction of a rolled material, and when detecting a uniformly heated state in the circumferential direction for a certain part in the longitudinal direction, and when detecting a uniformly heated state in the circumferential direction for other parts. This is because there are many differences between the two cases. Therefore, it is better to repeat the soaking state detection in the circumferential direction several times in the longitudinal direction of the rolled material and make a comprehensive judgment. Next, a method for detecting a soaking state will be specifically described. FIG. 2 is a diagram showing an example of detecting a soaking state. In the figure, 41 to 47 are rollers for transporting the rolled material 3. 51,5
2, 53, 54, 55,...5n (5n is not shown)
shows a temperature detector that detects temperatures at multiple locations in the circumferential direction of the rolled material 3. 6 indicates a calculator, 61
62 is a process input/output device that takes in the process amount (in this case, the temperature T ₁ to _{T o} of each part in the circumferential direction of the rolled material) and outputs control data for the process; 62 is the process amount from the process input/output device 61; A central processing unit 63 that performs some kind of calculation (in this case, detection of the soaking state) using the above-mentioned CPU 63 has a built-in storage device that stores programs, process amounts, calculation results, and the like. 7 is a data input section for supplying necessary programs, data, etc. to the computer 6 in advance. Reference numeral 8 denotes a display unit such as a display device that allows the operator to recognize the calculation result (in this case, the soaking state) calculated by the computer 6. In such a configuration,
The rolled material 3 extracted from the furnace is detected by temperature detectors 51 to 5.
When the n installation position is reached, the output of each temperature sensor increases rapidly. By monitoring this sudden change, the computer 6 can detect that the rolled material 3 has reached the temperature detector installation position. Note that this detection can also be performed by providing an appropriate detection means, such as a hot metal detector or a limit switch, near the installation position of the temperature detector. Upon detection of the rolled material 3, the central processing unit 62 in the computer 6 outputs T ₁ which is the output of each of the temperature detectors 51 to 5n via the input/output device 61.
~T _o is stored in the storage device 63. and,
The central processing unit 62 calculates the soaking state using the stored values T ₁ to _{T o} in accordance with a program that has been previously input from the data input unit 7 and stored in the storage device 63 . This calculation result is output to the display section 8 and is also stored in a predetermined area within the storage device 63. If the soaked state of one rolled material 3 is detected multiple times in the length direction of the rolled material 3, a more accurate soaked state can be recognized.
For example, it is possible to detect the uniform heating state at the tip, center, and rear end of the rolled material and display them respectively on the display means 8, or to display only the worst uniform heating state among them, or to display the average heating state among them. Displays the uniform heating status. These displays can be freely selected depending on the situation and usage. Regarding the detection of the soaking state shown in FIG. 2, a specific flowchart for detecting the soaking state is shown in FIG. When the computer 6 stores a program according to such a flowchart in its storage device 63, it is possible to detect the soaking state. In Fig. 3, as is clear from the flow, the temperature in the circumferential direction of the rolled material T ₁
- Take in T _o (steps F0 to F2), select the highest value T _MAX and lowest value T _MIN (steps F3 to F9), and determine the soaking state based on the difference ΔT _M between them. Detected (steps from F10 to F12)
are doing. Here, in step F11, specifically, for example, a table as shown in Table 1 is stored in the storage device 63.
Calculate the uniform heating state by referring to this table. In addition, in order to control the process amount (for example, the furnace time, etc.) using this soaking state, we have obtained the result that it is possible to control more accurately by using ΔT _M as is.

[Table] Using the calculation result of ΔT _M , in step F11,
Select which level (index, state, necessity of control) this ΔT _M falls within. The results are then output to the display unit 8 as shown in step 12. Therefore, the operator can check the current state of uniform heating, and can realize appropriate operation. Detection of the soaked state is not limited to the method shown in FIG. 3, but the most suitable detection method should be adopted depending on the type and characteristics of the target process. Next, another soaking state detection method of the present invention will be explained. FIG. 4 is a drawing showing another embodiment of the present invention. In the figure, the same numbers as in FIG. 2 indicate the same parts. 5 is a thermometer installed near the rolling mill. This rolling mill is a Mannesmann type perforation machine, and this type of rolling mill performs perforation while applying rotation to the rolled material 3 by the roll 1. Therefore, even if a plurality of temperature detectors (for example, 51 to 5n in FIG. 2) are not provided in the circumferential direction of the rolled material 3, if one temperature sensor 5 is provided, the temperature in the circumferential direction of the rolled material 3 can be determined. Can recognize distribution. This recognition is possible because the temperature is detected in a spiral as the rolled material 3 moves forward while rotating, so it cannot be said to be completely circumferential, but it is possible to uniformly heat the rolled material in the circumferential direction to the extent that there is no problem in practical use. Condition can be detected. That is, as shown in FIG. 5, as the rolled material 3 rotates in the direction A, the temperature detector 5 measures the temperature of the portion of the rolled material 3 marked with an x. To measure the temperature in the circumferential direction of a rolled material like this, rather than measuring once for one rolled material, measurements are performed multiple times as shown in a and b in the figure, and the soaking state is detected for these measurements. As in the previous example, doing so will yield more useful results. The specific detection method for the embodiment shown in FIG. 4 will be explained as follows. In this embodiment, the temperature is measured in the circumferential direction of the rolled material as shown in FIG _. ) N _P is detected by the speedometer 9. FIG. 6 shows this relationship. 6th
In the figure, v is the rotational speed of the material 3, v _L is the approach speed, and v _R is the vertical component speed. D is the outer diameter of the rolled material 3. Here, the relationship between v and v _R and v _L is as follows, as is clear from the figure: v _R = v sinθ (1) v _L = v cosθ (2). Here, if the diameter of the roll 1 is D _P and the backward movement rate between the roll and the material is taken as v=kN _P ·π·D _P (1−) (3) k: constant. Therefore, the time required for the material to rotate once
t _R is: t _R = πD/v _R = π・D/kN _P・π・D _P (1−) sinθ ……(4) Here, the number of times the temperature T _i is measured during one rotation of the material When n is the sampling time t s , the sampling time t _s is expressed as t _s =t _R /n (5). Therefore, in the computer 6, first, D _P , , which is set by the input means 6 and stored in the internal storage device.
Using D, θ, n, etc. and the output N _P of the speedometer 9,
Determine the sampling period t _s . When the rolled material 3 reaches the installation position of the temperature sensor 5 (for example, at an appropriate point after being bitten by the rolling mill), the output of the temperature sensor 5 changes at each previously determined period of time _ts . T _i
take in. When the number of attachments reaches n times, the single loading operation ends. Then, as in the previous embodiment, the soaking state is detected using the n temperature measurement values T ₁ to _{T o} . Then, the detection result is output to the display means 8. When the rolled material 3 has entered the rolling mill to a certain extent, the temperature detector 5 is turned on again at a period of _ts .
The output T _i of is taken in and the soaking state is detected in the same way.
In other words, the soaking state in the circumferential direction of the rolled material is detected by repeating it multiple times in the longitudinal direction of the rolled material. In this way, not only the accurate soaking state of the rolled material can be determined, but also the soaking state becomes a useful parameter when controlling a furnace, rolling mill, etc. using this soaking state. In the example shown in Fig. 4, the rolled material is rotated in the rolling mill, so this is used, but in a rolling mill that does not rotate the rolled material, it is not possible to use 1 as it is.
The soaking state cannot be detected by individual temperature detectors.
In this case, the same can be achieved by providing a temperature detector at an appropriate location while the rolled material is extracted from the furnace and transported to the rolling mill, and by providing equipment for applying rotation to the rolled material. In addition, the temperature sensor can be moved in the circumferential direction of the rolled material without rotating the rolled material.
Temperature detection values from time to time may be used. As explained above, it is possible to detect the uniform heating state in the circumferential direction of the rolled material with just one temperature detector, and it can also be realized with two or more temperature detectors. It should be clear from this. As described above, according to the present invention, the effect of being able to accurately detect the soaking state of a bar-shaped rolled material is achieved.

[Brief explanation of the drawing]

Fig. 1 is a drawing showing an example of a rolling mill for perforation, Fig. 2 is a drawing showing an embodiment of soaking state detection according to the present invention, and Fig. 3 is a flowchart showing a specific method of soaking state detection. The drawings, FIG. 4, are drawings showing another embodiment of soaking state detection according to the present invention, and FIGS. 5 and 6 are drawings for explaining the embodiment shown in FIG. 4. 5, 50, 51 to 55 are temperature detectors, 6 is a calculator, 7 is a data input section, 8 is a display section, and 9 is a speedometer.

Claims (1)

[Scope of Claims] 1. Prior to supplying the rod-shaped rolled material taken out from the furnace to a piercing rolling mill and forming it into a tube shape, the rod-shaped rolled material is rotated, and at the entry point of the rod-shaped rolled material. The rotational speed of the bar-shaped rolled material is adjusted such that the output of the one or more temperature detectors provided is adjusted to a predetermined interval between temperature measurement points in the circumferential direction of the surface of the bar-shaped rolled material. A method for detecting uniform heating of a rolled material, characterized in that the uniform heating state of the bar-shaped rolled material in the circumferential direction is detected based on the distribution of the plurality of measured values taken in at time intervals calculated from the above. . 2. In the soaking temperature detection method according to claim 1, when detecting the soaking state, a maximum value and a minimum value among the temperature measurement values at a plurality of points are used, and the maximum value and the minimum value are used. A method for detecting uniform heating of a rolled material, characterized in that a value of the difference between the values is used as an index of the uniform heating state. 3. In the soaking temperature detection method according to claim 1, the one or more temperature detectors are installed near a rolling mill that performs a rolling operation while giving rotation to the rolled material, and the rolled material is A soaking temperature detection method characterized by omitting a special operation of rotating at a predetermined speed. 4. In the method for detecting soaked heat according to claim 3, the temperature is measured at a plurality of locations in a spiral manner in the longitudinal direction of the rolled material, and the soaked state in the circumferential direction of the rolled material is detected multiple times in the longitudinal direction. A method for detecting uniform heating of rolled material, characterized by: