JPH06147870A - Length measuring method for extruded pipe - Google Patents

Abstract

PURPOSE:To provide a method for measuring the length of a pipe under hot state immediately after extrusion through a seamless pipe manufacturing line in which the length of pipe can be measured accurately regardless of the outer diameter, length or snaking of the extruded pipe without disturbing an existing manufacturing process while withstanding radiation (90 deg.C or higher) from the pipe member with a simple mechanism. CONSTITUTION:Immediately after extrusion by an extrusion press, an extruded pipe 2 under hot state is irradiated, on the outer peripheral surface thereof, with a microwave at a predetermined angle theta and the microwave reflected therefrom is received. The length of the extrusion pipe 2 is measured based on Doppler frequency produced by mixing an irradiating microwave with a reflection microwave subjected to frequency variation by Doppler effect caused by the extrusion speed (v) of the extrusion pipe 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the length of a seamless pipe in a hot state (extruded pipe) extruded immediately after an extrusion press in the process of producing a seamless pipe by the Mannesmann system or the Eugene Sejournet system, for example. The present invention relates to a method for measuring the length of an extruded tube for measuring the temperature.

[0002]

2. Description of the Related Art FIG. 3 is a cross-sectional view of a general extrusion press, which is the center of seamless pipe production. In FIG. 3, 1 is a billet (material) before extrusion and 2 is an extruded pipe. (Seamless pipe), 3 is a main ram for exerting an extrusion pressure on the billet 1, 4 is a mandrel (tool) arranged at the center of the billet 1 and the extrusion tube 2 and determining the inner diameter / inner shape of the extrusion tube 5, A dummy block (tool) provided between the billet 1 and the main ram 3 is a die for extruding the extrusion pipe 2 while pressing the main ram 3 to narrow the billet 1 to form a predetermined outer diameter / outer shape. (Tool), 7 is a container that holds the billet 1 and is pushed into the main ram 3.
(Tool), 8 is a die holder (tool) for holding the die 6 in the container 7, 9 is a hot saw for cutting the extrusion pipe 2, 10 is a head, 11 is between the head 10 and the die holder 8. A tray is provided to receive the die 6 through the die holder 8, 12 is a die advance cylinder for advancing the die 6 through the tray 11 and the die holder 8, and 13 is for feeding the extruded pipe 2 extruded from the die 6. It is a roller table.

The material (billet) before extrusion is supplied to the extrusion press 14 having the above-described structure after being adjusted to have a constant length and outer diameter.
Depending on the product, seamless pipe (extruded pipe 2)
Since the outer diameter and the wall thickness of the extruded tube 2 are different, the length of the extruded tube 2 to be extruded also largely changes (for example, 4 to 23 m). Moreover,
Since the outer diameter and wall thickness change and uneven thickness occurs, the pipe length further changes.

The length measurement of this seamless pipe is indispensable for adjusting the size of the product. Conventionally, for example, as shown in FIG. 4, a ball screw is visually checked in advance on a cutting machine line after extrusion. By rotating 17 the set-size movable stopper 18 is set at a predetermined position and the tip of the extruding tube 2 is brought into contact with the stopper 18, and the length measurement is generally performed. In FIG. 4, 15 is a roll gang, 16 is a cooling bed, and 19 is the end of the extruded tube 2 which is a stopper 1.
It is a cutting machine that cuts the extruded pipe 2 into a predetermined length in a state of being in contact with 8.

Generally, a measuring roll that rotates in contact with the extruded tube 2 is used, but as shown in FIG. 5A, recently, the extruded tube 2 in a hot state is extruded by a laser Doppler radar. It has also been proposed to measure velocity and tube length. In FIG. 5, reference numeral 20 denotes a laser speedometer. The laser speedometer 20 irradiates the outer peripheral surface of the extruded tube 2 with a laser beam 20a, receives the laser beam 20b reflected from the outer peripheral surface, and receives the speed of the extruded tube 2. The velocity v is obtained from the Doppler shift caused by v, and the measurement accuracy is high and the response is good. The length of the extruded tube 2 is measured by integrating the velocity v thus measured with time.

[0006]

However, in the length measuring means using the measuring roll, slippage between the measuring roll and the extruded tube 2 causes a large error, and the length of the extruded tube 2 is adjusted according to the size. If it is to be pinched, the extruded tube 2 may be damaged, or a complicated mechanism or control device that takes heat resistance into consideration is required. Further, when a measuring roll is used, there is a problem that it is difficult to judge the start and end points of wear and rotation of the roll.

On the other hand, in the length measuring means using the laser speedometer 20, no problem occurs when the length measuring object is a flat plate, but when a pipe material such as the extruded pipe 2 is the length measuring object, FIG. As shown in b), when the irradiation position of the laser light 20a deviates from the axial center of the extruded tube 2, the reflected laser light 20c cannot return to the detection unit of the laser speedometer 20. In particular, the extrusion pipe 2 extruded from the extrusion press 14 as described above.
In the case of, the horizontal shake (meander) is large. In addition, since the actual manufacturing size is wide with a diameter of 27 to 120 mm, the position where the laser light 20a strikes greatly changes.

In the length measuring means shown in FIGS. 5 (a) and 5 (b), since the laser beam 20a having a very high directivity is used, the depth of focus is at most 4-5 mm.
It is necessary to follow up and down according to the pipe diameter. Further, since the lateral shake is large as described above, in order to be able to cope with this, a vertical, horizontal and lateral follow-up device is required and the mechanism becomes extremely complicated. The extrusion speed of the extrusion tube 2 is usually 20
Since the amount of meandering is ± 70 to 80 mm at around 0 to 300 m / min, it is extremely difficult to follow accurately.

If the reflected light 20c such as the solid line in FIG. 5 (b) is generated and cannot be followed, the speed measurement output from the laser speedometer 20 becomes zero, which is to be obtained from the integrated value of the speed measurement output. The tube length of causes a negative error.

However, it is advantageous to measure at points A or C shown in FIG. This is because, in the measurement at the point B shown in FIG. 4, although one of the tube ends could be fixed at a certain position, the other tube end was widely distributed, so that the other tube end was in this range. It is difficult to find a means for accurately measuring the position of the pipe end in a short time.

The present invention is intended to solve such a problem, and accurately measures the current production process without disturbing the outer diameter, length, and meandering of the extruded pipe. An object of the present invention is to provide a method for measuring the length of an extruded pipe that can withstand the radiation (900 ° C. or higher) from the pipe material with a simple mechanism while making it possible to increase the length.

[0012]

In order to achieve the above object, the method for measuring the length of an extruded pipe according to the present invention is such that the extruded pipe is extruded from the outer peripheral portion of the extruded pipe in a hot state immediately after being extruded from an extrusion press. Irradiate microwaves at a predetermined angle toward the outer peripheral surface of
The microwave reflected from the outer peripheral surface of the extruded tube is received, and the reflected microwave has a frequency changed by the Doppler effect accompanying the extrusion speed of the extruded tube, and is obtained by mixing with the irradiated microwave. The length of the extruded tube is measured based on the Doppler frequency.

[0013]

In the above-described extrusion pipe length measuring method of the present invention, the extruded pipe extruded from the extrusion press is irradiated with microwaves, and the reflected microwaves cause the Doppler effect accompanying the extrusion speed of the extruded pipe. The length of the extruded tube can be accurately measured based on the frequency changing by the method without disturbing the existing production process and without being affected by the outer diameter, length and meandering of the extruded tube.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An extruded pipe length measuring method as an embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing an apparatus to which the method is applied, and FIG. 2 is a diagram showing the Doppler frequency in this embodiment. It is a wave form diagram which shows an example.

In FIG. 1, 21 is a conveying roll for conveying the extruded pipe (seamless pipe) 2 in a hot state immediately after being extruded from an extrusion press (see reference numeral 14 in FIGS. 3 and 4), and 22 is a microwave. In the oscillator, the microwave oscillator 22 includes a Gunn diode 22b driven by a stabilized DC power supply 22a. Gunn diode 2
As 2b, for example, a stabilized DC power source 22a of 10V is used.
24.5GH with 150mW output when driven by
A device that outputs a microwave having an oscillation frequency (f) of z (wavelength λ = 12.2449 mm) is used.

Reference numeral 23 is a horn antenna connected to a microwave oscillator 22 via a waveguide 25 having a circulator 24 interposed therebetween. The horn antenna 23 guides the microwave from the microwave oscillator 22. The microwaves are guided through the tube 25 and are radiated from above onto the outer peripheral surface of the extruded tube 2 at a predetermined angle θ with respect to the vertical line.

Here, for example, the waveguide 9 is JIS
A standard product is used, and the horn antenna 23 has a gain of 30.
For db, directivity with a half width of ± 7 ° is used. Further, the horn antenna 23 is located near 400 mm above the extruded tube 2 so as to face the extruding direction of the extruded tube 2, and the front surface of the horn antenna 23 is made of thin alumina (Al ₂
A plate material (not shown) made of O ₃ ) is arranged to prevent radiation from the extruded tube 2.

Further, since the glass film of the lubricant is adhered to the surface of the extruded tube 2 immediately after being extruded, even if the installation angle θ of the horn antenna 23 is slightly large, the extruded tube 2 is exposed from the surface of the extruded tube 2. The reflected (scattered) wave of the microwave is sufficiently large and the reflected microwave surely returns to the horn antenna 23. However, considering the range of the diameter of the extruded tube 2 and the meandering,
The suitable installation angle θ is around 20 ° to 40 °,
In this embodiment, the angle is 30 °, for example.

Further, the measurement position, that is, the microwave irradiation position is near the point A or B shown in FIG. 4, and in order to avoid unnecessary reflection from an unrelated rotating object (conveying roller 21 or the like), As shown in FIG.
It is desirable to choose the midpoint of.

Reference numeral 26 is a mixer (mixer), and this mixer 26 reflects the reflected microwave of frequency f + fd including the frequency fd of the Doppler shift reflected from the surface of the extruded tube 2 into the horn antenna 23 and the waveguide. 25 and the circulator 24 to generate a beat wave having an oscillation frequency f of the microwave oscillator 22 and a frequency fd as shown in FIG. Here, the frequency fd for the Doppler shift
Is expressed by the following equation using the extrusion speed v, the irradiation angle θ, and the wavelength λ of the microwave.

Fd = 2v · sin θ / λ 27 is an amplifier for amplifying the beat wave of the frequency fd from the mixer 26 to a constant amplitude, and 28 is a voltage proportional to the frequency fd of the beat wave, which receives the beat wave from the amplifier 27. A frequency / voltage converter (F / V converter) that outputs a signal, that is, a speed signal proportional to the extrusion speed v of the extrusion tube 2, 29 is a zero-cross point of the beat wave of the frequency fd from the amplifier 27.
A zero cross counter (Z) (see FIG. 2) is used to detect the number of points detected by a comparator or differentiator (not shown).
CC) and 30 are converters for converting the count result of the zero cross counter 29 into the length 1 of the extruded tube 2, which is reset by a reset signal from the zero cross counter 29.

With the above configuration, the microwave generated from the Gunn diode 22b driven by the DC power source 22a is guided to the horn antenna 23 through the waveguide 25,
Irradiation is performed at an angle θ toward the outer peripheral surface of the extruded tube 2 in a hot state immediately after being extruded from the extrusion press. The oscillation frequency f of the microwave changes due to the Doppler effect associated with the extrusion speed v of the extrusion tube 2, and the frequency f + fd
Then, due to the fine irregularities on the surface of the extruded tube 2, the microwaves are reflected / scattered in various directions, and some microwaves return to the horn antenna 23 again.

The microwave having the frequency f + fd is guided to the mixer 26 through the waveguide 25 and the circulator 24, and beat waves having the oscillation frequency f and the frequency fd are produced. The frequency fd for the Doppler shift is at most several hundreds Hz, and the observed waveform has some amplitude change as shown in FIG. However, since the beat wave of the frequency fd is amplified to a constant amplitude by the amplifier 27, it is converted into a voltage signal proportional to the frequency fd by the frequency / voltage converter 28, resulting in the extrusion speed v of the extrusion tube 2. An output proportional to is obtained.

It is possible to integrate the analog signal of the extrusion speed v thus obtained to obtain the length of the extrusion tube 2, but there is a problem in terms of accuracy. Therefore, as shown in FIG. The zero cross point of the beat wave is detected by a comparator or differentiator, the number is counted by the zero cross counter 29, and the count result is converted by the converter 30 to accurately measure the length of the extruded tube 2. be able to.

For example, the extrusion speed v of the extrusion tube 2 is 3 m / s.
When ec, the frequency fd for the Doppler shift is 245H
With z, the zero-cross point detection in this frequency band is extremely easy. The measurement accuracy at a pipe length of 20 m is around ± 8 mm, which is extremely high. Further, the beat wave signal of the frequency fd becomes 0 when the extruding tube 2 is not on the transport roller 21, so that the beat wave signal exists only during the continuous period.
By counting with the zero-cross counter 29, the length of the extruded tube 2 can be measured.

As described above, according to the extrusion pipe length measuring method of this embodiment, the extrusion pipe 2 in the state of being extruded from the extrusion press is irradiated with microwaves, and the reflected microwaves are reflected by the extrusion pipe 2. Based on the frequency that changes due to the Doppler effect associated with the extrusion speed v of the extruding pipe 2, the size (outer diameter, length) of the extruding pipe 2 can be changed without modifying the existing production equipment and operation.
The length of the extruded tube 2 can be accurately measured without being affected by meandering or meandering.

As a result, the dimension can be adjusted during the operation, the cutting can be directly connected to the post-process, the wall thickness variation can be predicted from the extrusion speed v, and the radiation from the extrusion pipe 2 can be estimated by an extremely simple mechanism. Can withstand enough.

There is also an advantage that the length of the extruded tube 2 can be measured extremely accurately by counting the zero-cross points of the beat wave having the frequency fd for the Doppler shift.

[0029]

As described above in detail, according to the extrusion pipe length measuring method of the present invention, the extrusion pipe extruded from the extrusion press is irradiated with microwaves, and the reflected microwaves Based on the frequency that changes due to the Doppler effect with the extrusion speed of the extrusion tube, the length of the extrusion tube does not disturb the current production process and is not affected by the outer diameter, length and meandering of the extrusion tube. Can be accurately measured, and with a simple mechanism, it has the effect of withstanding radiation from pipe materials.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an apparatus to which an extruded pipe length measuring method according to an embodiment of the present invention is applied.

FIG. 2 is a waveform diagram showing an example of a Doppler frequency in this embodiment.

FIG. 3 is a cross-sectional view of a general extrusion press.

FIG. 4 is a plan view schematically showing an example of a conventional extruded pipe length measuring device.

5 (a) and 5 (b) are respectively a side view and a front view showing an example of a conventional extruded pipe length measuring means using a laser velocimeter.

[Explanation of symbols]

 2 Extruded pipe (seamless pipe) 21 Conveyor roll 22 Microwave oscillator 22a Stabilized DC power supply 22b Gunn diode 23 Horn antenna 24 Circulator 25 Waveguide 26 Mixer (mixer) 27 Amplifier 28 Frequency / voltage converter (F / V converter) ) 29 Zero Cross Counter (ZCC) 30 Converter

Claims (1)

[Claims] 1. A microwave is radiated at a predetermined angle from the outer peripheral portion of the extruded tube in a hot state immediately after being extruded from the extrusion press machine to the outer peripheral surface of the extruded tube, and the outer peripheral surface of the extruded tube is irradiated. The reflected microwave is received, and the reflected microwave has a frequency changed by the Doppler effect accompanying the extrusion speed of the extrusion tube, based on the Doppler frequency obtained by mixing with the irradiated microwave, An extruded pipe length measuring method, characterized in that the length of the extruded pipe is measured.