JPS61119318A - Monitoring method of thickness deviation generation of seamless pipe - Google Patents

Abstract

PURPOSE:To reduce the generation of a defective product by thickness deviation with taking quickly the counter measure for thickness deviation prevention by measuring the displacement quantity with providing a displacement measuring instrument on the outlet side of a inclined roll and by monitoring the thickness deviation generating state based on the measured value thereof. CONSTITUTION:The laser beam generated at the laser beam generating part 61 of a displacement measurer 6 is irradiated on a hollow shell S or mandrel bar 3 through an irradiating lens 62. The reflected beam thereof is projected on the detecting face of the optical detecting element 64 which is provided in parallel in the moving direction of the hollow shell S through an image forming lens 63. The displacement quantity in the shaft core direction of the hollow shell S and mandrel 3 can be taken as the displacement quantity in the shaft length direction and with detecting the signal thereof by a position detecting part 65 the detecting signal is recorded to a recording meter 70.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention deals with the occurrence of uneven thickness in the manufacturing process of seamless pipes in which a material is perforated or rolled using a pair of inclined rolls and a plug provided at the tip of a mandrel bar. on how to monitor.

[Prior art]

In the production of seamless steel pipes using the inclined rolling method, materials such as heated steel ingots and billets are made into hollow pipes using a punching machine, which is then stretched and thinned using a rolling machine to become seamless steel pipes. be done. Conventionally, there was no method for monitoring uneven wall thickness that occurs during drilling or rolling, and there was a method that measured the wall thickness during the finishing process at the final stage of steel pipe manufacturing and controlled the drilling and rolling machines based on the measurement results. It was done.

[Problem that the invention seeks to solve]

However, with this method, many defective products with uneven thickness were manufactured before the occurrence of uneven thickness was discovered, and no practical effect could be expected. In addition, a method for diagnosing the cause of uneven thickness by continuously measuring rolling conditions (Japanese Patent Laid-Open No. 57-9441
No. 0) has also been developed, but this has the problem that it can only detect the occurrence of uneven thickness during rolling, but cannot detect the state of uneven thickness during drilling, which is an upper process.

[Means to solve the problem]

The present invention has been made to solve such problems, and its purpose is to monitor the whirling amplitude of mandrel bars and hollow shells whose centers are deviated due to uneven thickness, so that they can be used not only during rolling but also during drilling. It is also possible to detect the occurrence of uneven thickness, and to quickly take measures to prevent uneven thickness, such as preventing uneven heat in steel slabs, adjusting the inclination and eccentricity of the drilling plug, and adjusting the position ff of the drilling machine. An object of the present invention is to provide a method for monitoring the occurrence of uneven wall thickness in seamless pipes, which makes it possible to significantly reduce the occurrence of wall thickness unevenness in seamless pipes.

In the method for monitoring the occurrence of uneven thickness in seamless pipes according to the present invention, while the material passes through the gap between the pair of inclined rolls, the mandrel bar
In the manufacturing process of seamless pipes, in which the material is perforated or rolled with a plug provided at the tip, a displacement measuring device is installed on the outlet side of the inclined roll, and from there to the mandrel bar and/or seamless pipe during perforation or rolling. It is characterized by measuring the amount of displacement of the distance and monitoring the internal occurrence state based on the measured value.

〔principle〕

Fig. 1 is a schematic diagram of a plug mill rolling mill that is applicable to the method of the present invention. In Fig. 0, 1 is a pair of inclined rolls whose axes are mutually inclined. It is arranged so that it can rotate freely. A plug 2 attached to the tip of a mandrel bar 3 is located between each roll 1, and when the hollow shell S moves in the direction of the white arrow, the hollow shell S is perforated by the plug 2.

The proximal end of the mandrel bar 3 is attached to a thrust block 4, and the plug 2 receives a thrust force from the thrust block 4. The middle of the mandrel bar 3 is supported by, for example, four bar step ears 51, 52, 53, and 54.

In a plug mill rolling mill with such a configuration, during rolling, each inclined roll is rotated to rotate the hollow shell S, and the hollow shell S is moved in the direction of the white arrow to bring the hollow shell S into contact with the plug 2. However, so-called uneven thickness may occur in the hollow shell S, in which the wall thickness in the circumferential direction and the axial direction is not constant.

In this case, the rotation of the hollow shell S causes the plug 2.
The mandrel bar 3 swings around, and in order to prevent this swing, each bar step ear 51°..., 54 is clamped, but this cannot be completely prevented, and as the tongue plug 2 swings around, Hollow Shell S also swings around. The amplitudes of the rotating mandrel bar 3 and hollow shell S were measured by installing a displacement measuring device 6 on the exit side of the inclined roll l.

Figure 2 (A) shows the whirling amplitude of the mandrel bar 3 during rolling and the thickness unevenness rate of the hollow shell S at that time [(maximum wall thickness -
It is a graph showing the relationship between minimum wall thickness)/maximum wall thickness],
FIG. 2(B) is a graph showing the relationship between the whirling amplitude of the hollow shell S during rolling and the uneven thickness of the hollow shell S at that time.

As is clear from this figure, it can be seen that when the amplitude of the mandrel bar 3 is large and when the amplitude of the hollow shell S is large, the thickness unevenness rate becomes high.

Therefore, by monitoring the amplitude of the mandrel bar 3 or the hollow shell S, it is possible to grasp the occurrence of uneven thickness.

〔Example〕

A case where the method of the present invention is applied to a plug mill rolling mill will be explained. As shown in Fig. 1, the plug mill rolling mill has an inclined roll l, a plug 2, a mandrel bar 3, a thrust block 4, a bar step ear 51, . . . , 54, etc., and the details are as described in ii. . A displacement measuring device (for example, a measurement sensor manufactured by Anritsu Electric Co., Ltd., M537^) 6 is fixed on the exit side of the inclined roll l.

FIG. 3 is a block diagram of the displacement measuring device 6. The displacement measuring device 6 has a laser beam irradiation system and a light receiving system separated by a predetermined hole in the axial direction of the hollow shell S and the mandrel bar 3. The mandrel bar 3 and the hollow shell S are installed so that the laser beam is directed toward the axes of the hollow shell S.

The laser beam generated by the laser beam generating section 61 of the displacement measuring device 6 is narrowed down while passing through the irradiation lens 62, and is also focused, for example, in the moving direction of the hollow shell S, and is emitted from the hollow shell S or the mandrel bar. 3 is irradiated,
The reflected light passes through the imaging lens 63 of the light-receiving system and is projected onto the light-receiving surface of the photo-detecting element 64 provided parallel to the moving direction of the hollow shell S, and is thereby directed toward the axial center of the hollow shell S and the mandrel bar 3. The amount of displacement is captured as the amount of displacement in the axial direction, and the captured signal is detected by the position detector 65 and the detected signal is recorded in the recorder 70.

When rolling with a plug mill rolling machine with such a configuration,
Rotate each inclined roll l, move the hollow shell S between the inclined rolls 1 in the direction of the white arrow, and
Rolling is performed by bringing the plug into contact with the plug 2. Each bar step ear 51, 52, 53, 54 clamps the mandrel bar 3 by a hydraulic cylinder (not shown), and suppresses swinging of the mandrel bar 3 during rolling.

During rolling, the hollow shell S rotates due to the rotation of the inclined roll 1, and the whirling of the plug 2 due to the rotation of the hollow shell S is suppressed by each bar step ear 51°..., 54, but it is difficult to suppress it completely. This whirling causes so-called uneven thickness, where the wall thickness in the circumferential and axial directions is not constant.

When this uneven thickness occurs, the amount of distance displacement between the displacement measuring device 6 and the mandrel bar 3 is After the tip of the hollow shell S reaches the laser beam of the displacement measuring device 6, the displacement measuring device 6
~ The distance displacement amount between Holo and Shell S will be measured, and all the measurement results will be recorded on the recorder 70 (
.

Therefore, for example, an operator can grasp the rolling status of a pipe by monitoring the records, and if the amplitude of the rotation of the mandrel bar 3 or hollow shell S is large, the operator can immediately stop rolling, or stop rolling after rolling the pipe and remove the metal. piece,
For example, measures to prevent uneven thickness should be taken immediately, such as preventing uneven heat in steel pieces, adjusting the inclination and eccentricity of the drilling plug, and adjusting the position of the drilling machine.

This makes it possible to roll a pipe with suppressed thickness deviation from the next material pipe.

〔effect〕

The effects of the present invention will be explained below. According to the present invention, the occurrence of thickness deviation during rolling is monitored, and hollow shells with very small thickness deviations, small thickness deviations, and large thickness deviations are checked after rolling. It was determined by an ultrasonic wall thickness meter that the thickness was constant over the entire length and around the entire circumference.

Figure 4 is a graph summarizing the measurement results, (al
(b) shows the result when the thickness deviation is extremely small, (bl shows the result when the thickness deviation is small, and (cl) shows the result when the thickness deviation is large, and (a) is measured with the displacement measuring device 6. As a result, (b) and (c) show the measurement results of the wall thickness over the entire length and the entire circumference at a certain circumferential position, respectively, using an ultrasonic wall thickness meter. (The lower left line in each (a) of C1 indicates the displacement of the mandrel bar 3, the upper right line indicates the displacement of the hollow shell S, and in the figure, ■ is at the start of rolling, ■, ■, ■ are the bar stepper 51 When the tip of the hollow shell S reaches .52.53, ■ indicates the position at the end of rolling, and the broken lines at each (B) and (C) indicate the nominal value of the rolled seamless pipe, and the dashed line indicates its position. As can be understood from this figure, which shows the upper and lower limits, when the amount of thickness deviation is small, the amplitude of the measured value according to the present invention is small, and when the amount of thickness deviation is large, the amplitude appears large. By monitoring this, it is possible to accurately determine whether or not thickness unevenness has occurred, and by promptly taking predetermined measures to prevent thickness unevenness based on the determination results, the occurrence of defective products with uneven thickness can be significantly reduced.

In addition, in the above embodiment, the amplitude of whirling of the mandrel bar and hollow shell is optically detected, but the present invention is not limited to this, and the present invention can also be carried out by measuring with other non-contact type or contact type displacement needles. Of course it can be done.

As detailed above, in the case of the present invention, at the time of drilling.

Since it is possible to accurately determine the presence or absence of uneven thickness during rolling, it is possible to promptly take measures to prevent uneven thickness based on the determination results, thereby making it possible to significantly reduce the occurrence of defective products with uneven thickness. The present invention has excellent effects.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram of a plug mill rolling mill to which the method of the present invention is applied, and Figs. 2 (a) and (b) show the relationship between the thickness unevenness ratio and the swinging amplitude of the mandrel bar, and the relationship between the thickness unevenness ratio and the swinging amplitude of the hollow shell. FIG. 3 is a block diagram showing an example of a displacement measuring device, and FIG. 4 is an explanatory diagram of determining the occurrence of uneven thickness by the method of the present invention. ■... Inclined roll 2... Plug 3... Mandrel bar 4... Thrust block 6... Displacement measuring device 51, 52, 53, 54... Bar step ear S... Hollow shell patent Applicant Sumitomo Metal Industries Co., Ltd. Agent Patent Attorney Norio Kono / 6" Madre Iv...
- to) OI5 30 main low;
nm) Figure 2

Claims (1)

[Claims] 1. In the seamless pipe manufacturing process in which the material is perforated or rolled with a plug provided at the tip of a mandrel bar while the material passes through the gap between a pair of inclined rolls, a displacement measuring device is installed on the exit side of the inclined rolls. Displacement of a seamless pipe is provided, and the amount of displacement of the distance from the mandrel bar and/or the seamless pipe during drilling or rolling is measured, and the state of occurrence of uneven thickness is monitored based on the measured value. Meat development monitoring method.