JPS5916526B2 - Outer diameter correction method and device for diameter-sizing machine for seamless steel pipe production - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method and apparatus for adjusting the outer diameter of a finished pipe by adjusting the roll gap of a stand in a diameter-sizing machine for manufacturing seamless steel pipes, and relates to a method and apparatus for adjusting the outer diameter of a finished pipe in the axial direction The present invention relates to a method and an apparatus for making the outer diameter uniform over the entire length and rounding it during outer diameter drawing using a diameter-sizing machine.

Conventionally, seamless steel pipes are manufactured using the plug mill method by first uniformly heating round billet material in a heating furnace to rolling temperature.
The heated billet is perforated with an inclined boring machine to form a hollow tube, and then this hollow tube is rolled to approximately the required dimensions with a plug mill, and then sent to a polishing machine to polish the inside and outside surfaces, and then passed through a diameter-sizing machine. It is manufactured by going through a series of steps to finish it to the required outer diameter and thickness.

The diameter sizing machine mentioned above is a device that performs the final drawing finish in the seamless pipe manufacturing process by hot rolling.
- Several stands with tilted roll axes of the le straddle method (chock support type) are arranged in series with the roll axis directions intersecting each other by 90 degrees, and the raw pipe is passed through these stands continuously. This is a device that gradually decreases the outer diameter to a desired final outer diameter.

In this case, the billet, which is heated to a constant temperature in the heating furnace, passes through a plug mill and a polishing machine after perforation, and as the raw tube is formed into the desired shape, it is sent to each device during the processing process. The drop in temperature at the front end creates a temperature difference in the longitudinal direction, and the temperature of the raw tube just before the diameter sizing machine is usually about 700 to 900 degrees Celsius, but the temperature at the bottom is about 700 to 900 degrees Celsius compared to the head. There is a temperature difference of 50 to 100°C higher.

For this reason, when a raw pipe with such a temperature difference, that is, a temperature gradient, is rolled with a diameter-sizing machine, even though the outer diameter is uniform immediately after passing through the diameter-sizing machine, there is a temperature difference in the longitudinal direction as described above. Since the high-temperature portion will shrink more, the outer diameter of the corresponding portion of the finished tube after cooling is small, and since the outer diameter of the low-temperature portion has a smaller thermal contraction, the corresponding portion of the finished tube after cooling will have the smaller outer diameter. It will have a larger outer diameter than the high temperature part.

The above is the main cause, generally 0.3 to 0 for the head and wide area.
．． This means that a difference in outer diameter of 5 trrm will occur in one finished tube.

For this reason, particularly when products such as oil country tubular goods with strict outer diameter tolerances are manufactured using a diameter-sizing machine, the diameter-setting operation takes an extremely long time, resulting in a reduction in rolling capacity.

The above has described the seamless pipe manufacturing process using a unidirectional process. However, if the direction of the raw pipe is changed to the opposite direction due to location etc. and the finished pipe is rolled using a diameter-sizing machine, the head of the raw pipe Contrary to the above, the outer diameter of the finishing tube head will be smaller than the wide part because the temperature will be higher and the wide part will be colder.

In order to prevent the above-mentioned difference in the outside diameter of the finished tube and to make it uniform, a reheating method is disclosed in Japanese Patent Publication No. 15231-1983 in which a barrel furnace or induction heating furnace is installed in front of the diameter-sizing machine. However, this method has drawbacks such as high equipment costs and the need for a large installation space.

Furthermore, for the same purpose, the high-temperature part of the raw tube is cooled with water at the front of the diameter-sizing machine to equalize the temperature of the entire raw pipe, and this is rolled in the diameter-sizing machine to make the finished tube outside diameter uniform. A water cooling method has also been implemented, but this method has the drawback that uniform cooling is extremely difficult and, therefore, highly accurate finished pipe products cannot be obtained.

From the above-mentioned point of view, in order to eliminate the difference in outer diameter of the finished pipe rolled by the diameter-sizing machine, while the raw pipe is passing through the diameter-sizing machine, the final diameter of the finished pipe is rolled by the diameter-sizing machine according to a controlled drive method. The applicant has previously proposed a method and apparatus for uniformizing the longitudinal outer diameter of the cooled finished pipe product after passing through the diameter-sizing machine by gradually increasing or decreasing the roll gap of one or two stands of the pipe. .

However, although this proposal suggests the idea of measuring the temperature of the head and tail of the blank tube at the front of the diameter-sizing machine and controlling the roll gap based on the temperature difference,
This article does not disclose a control means for cases where the temperature gradient over the entire axial length of the raw pipe is nonlinear, and it is only possible to approximately equalize the outer diameter of a raw pipe with such a nonlinear temperature gradient. Moreover, there is no way to counter the axial change in the outer diameter that exists at the inlet of the diameter sizing machine, and furthermore, there is a time delay in checking the outer diameter after passing through the sizing machine, so manual adjustment is required by trial and error. It is true that it was not easy to correct the roundness of the finished tube.

This invention grasps the temperature distribution over the entire length in the axial direction of each raw tube fed into the diameter-sizing machine, and gradually changes the roll gap of the diameter-sizing machine stand accordingly to finish drawing. The purpose of this is to further ensure uniformity of the outer diameter over the entire length of the finished tube after cooling.

Another object of the present invention is to temporarily store the outer diameter and roundness of the pre-passed material that has already passed through the diameter-sizing machine as actual values in correspondence with its axial temperature distribution, so that the subsequent blank pipe can When the product is of the same type as the material, the above-mentioned actual value is used as control information to obtain a product with a uniform outer diameter.

That is, in the method for adjusting the outer diameter in a diameter-sizing machine for manufacturing seamless steel pipes according to the present invention,
During transportation, the raw pipe C is checked for passage and measured in front of the diameter-sizing machine, which has multiple stands to be controlled in series, and the temperature distribution over the entire length in the axial direction is measured just before entering the diameter-sizing machine. and sent to a diameter-sizing machine.

The diameter measuring machine detects the moving speed of the raw pipe between the stands and the biting of the raw pipe into each stand, and also detects the value of the roll gap of the stand to be controlled, and based on the length measurement results, the raw pipe concerned is 1. If it is determined that the material is not the same type as the material passing through before s, the roll gap of the stand to be controlled is gradually changed according to the temperature distribution and the reference target set value, and the raw pipe is cooled. Predictive control of the outer diameter is performed.

After passing through the diameter-sizing machine controlled in this way, the temperature of the raw pipe is measured over the entire length at the back of the diameter-sizing machine, and the outer diameter and roundness are also measured. The outer diameter distribution and roundness distribution over the entire length of the raw pipe are temporarily stored as actual values and used as control information for subsequent raw pipes of the same type.

In other words, if it is determined by length measurement at the front of the diameter sizing machine that the following blank pipe is the same type as the preceding material, the roll gap of the stand to be controlled is set to the actual value above based on the standard target setting value and the actual value above. Calculation control is performed to gradually change the diameter accordingly, making it possible to stably correct the outer diameter and roundness for drawing and finishing of the same type of raw pipe.

The present invention will be described in detail below based on the drawings of the embodiments.

The drawing is a block explanatory diagram showing a control system according to an embodiment of the present invention. A raw tube from a polishing machine is conveyed in the direction of the arrow on a conveyance line 1 and sent to a diameter-sizing machine 2.

A passing detector 3 such as a heated metal detector, which outputs an output when a raw pipe is present in front of the detection end, and a motor 5 that drives the rollers 4 of the conveyance line 1 are installed on the front side of the diameter sizing machine 2. A speed detector 6 such as a tachometer generator 6 is arranged in order, and further, a first temperature detecting device 7 such as a radiation thermometer for measuring the surface temperature of the passing blank pipe over the entire length is arranged immediately before the diameter measuring device 2. is installed.

The sizing machine 2 consists of a 20-le straddle multi-stage stand about the size of a normal stand, and each stand is equipped with a pulse generator 8 that outputs the number of roll rotations, and a roll position detector such as Selsin that detects the roll gap. 9. A load detector 10, such as a current relay, which outputs an output when the rolls bite the raw pipe, and a hydraulic motor 11 for adjusting the roll gap.
A flow rate control valve device 12 for controlling the flow rate control valve device 12 is provided, and a load cell 13 is provided as a backup for the load detector 10 as required.

Needless to say, the roll gap adjusting means may be constructed not only by a hydraulic device but also by a screw-down mechanism using an electric motor and a worm gear device.

A second temperature detecting device 7 similar to the first temperature detecting device 7 is provided on the rear surface of the diameter measuring device 2.
A temperature detecting device 14 and a non-contact tube outer diameter detecting device 15 are arranged adjacent to the temperature detecting device 14.

This outer diameter detection device 15 is configured, for example, by an optical non-contact measuring device using a photodiode array that scans in a direction perpendicular to the conveyance line 2. Furthermore, in order to include the roundness in the measurement results, it is necessary to It shall consist of a pair of measuring instruments that measure the outer diameter in two radial directions perpendicular to each other.

The arithmetic and control unit 16 connected to each of the detection systems and the roll gap control system includes a pipe length calculator 17, a temperature distribution generator 18, a pipe speed calculation and tracking device 19, an outer diameter calculation and storage device 20, and a main calculation unit. 21, and further includes the first
and second respective setting boards 22, 23 are connected.

The pipe length calculator 17 calculates the length of the raw pipe from the duration of the output of the passage detector 3 and the raw pipe speed measured according to the outer diameter of the raw pipe by the speed detector 6, and sends the length to the main calculation unit 21. convey a signal.

The temperature distribution generator 18 receives the surface temperature of the raw tube from the first temperature detection device 7 at predetermined time intervals, such as every 0.1 seconds, from the tip of the raw tube, stores it, and calculates the total length in chronological order. The temperature distribution signal over the entire length is sent to the main processing unit 21, and the average temperature of the entire length of the raw pipe is also calculated and output.

The tube speed calculation tracking device 19 receives the roll rotation speed from the pulse generator 8 and the raw tube jamming signal from the load detector 10 or load cell 13 from each stand of the diameter measuring machine 2, and calculates the data from each stand. Calculating the speed of the raw tube between the stands based on the time interval between the arrival time of the raw tube biting signal and the arrival time of the raw tube biting signal from the next stand and the fixed interval length dimension between both stands, The position of the tip or tail end of the tube at any time in the diameter sizing machine is tracked based on the arrival or disappearance point of the tube biting signal and the speed of the tube, and these calculations and tracking outputs are sent to the main processing unit 21.
Send to.

The outer diameter calculation storage device 20 stores raw pipe material information (including transformation point temperature), temperature expansion coefficient, target outer diameter value at a reference temperature, for example, 800°C, set by the second setting board 23, and the second In response to the temperature measurement results over the entire length of the raw pipe at the rear surface of the diameter measuring machine by the temperature detection device 14, and the results of measuring the outer diameter and roundness over the entire length of the raw pipe measured by the outer diameter detection device 15,
Correct the outer diameter measurement result to the outer diameter measurement value at the reference temperature,
This is compared with the target outer diameter value over the entire length, and the deviation over the entire length is temporarily stored together with the temperature as an actual value, and this stored content is sent to the main processing unit 21 as necessary.The first setting board 22 is , reference temperature, target outer diameter value, material information of the blank t, reference roll gap value of each stand, designation information of the stand to be controlled, etc. are set in the main processing unit 21 in advance.

The main processing unit 21 temporarily stores the pipe length signal from the pipe length calculator 17, compares the pipe length of the succeeding blank pipe with the pipe length of the pre-passing material, and further compares the temperature of the tip of both, and Based on whether or not the length and temperature at the tip of the subsequent blank tube are within a predetermined range with respect to the length and temperature at the tip of A command for selecting one of the modes and controlling gradual changes in the roll gap of the stand to be controlled by the diameter measuring machine is issued to the roll gap control device of the stand.

In other words, if it is determined that the subsequent raw pipe is not of the same type by comparison of the pipe length and tip temperature with the previous passing material (this naturally includes the first raw pipe entering the line), the main processing unit 21 Using the setting information such as target dimensions and material information regarding the corresponding raw pipe that is set according to the work schedule, the actual temperature distribution measurement value over the entire length of the raw pipe from the temperature distribution generator 18 is calculated. It is corrected by the amount by which the tube should shrink when it is cooled to room temperature, for example, and the roll gap of the stand to be controlled is corrected according to the temperature distribution measurement value, and the point and timing at which the part of the raw tube to be corrected reaches the stand is determined. At the same time, a control signal is sent to the flow rate control valve 12 so as to gradually increase or decrease the power, thereby performing drawing finishing over the entire length of the raw pipe so that the outer diameter of the finished pipe after cooling is uniform over the entire length. with a controlled gradual change in roll gap.

The raw tube that has exited the sizing machine 2 after undergoing such controlled drawing finishing passes through a second temperature detection device 14 and an outer diameter detection device 15 in order to determine the temperature change pattern over the entire length and the outer diameter change pattern. The pattern is measured, and the outside diameter calculation storage device 20 stores temperature-corrected actual values of the change pattern over the entire length of the outside diameter of the raw pipe based on these measurement results and setting information from the setting board 23, as well as the actual value of the raw pipe. Performance values including roundness based on outer diameter values measured in two mutually perpendicular radial directions of the pipe are calculated and temporarily stored.

Control of the roll gap of the diameter-sizing machine using the above control mode can be carried out using the front side of the diameter-sizing machine, for example, when the material, dimensions, temperature, etc. of the blank tube charged into the diameter-sizing machine are uniformly determined. The curve of temperature change over the entire axial length of the raw pipe was experimentally determined in advance as a characteristic corresponding to the equipment and work schedule, and the temperature at the tip of the raw pipe was measured in front of the diameter sizing machine. This measurement result and the temperature change curve may be used to determine the pattern of gradual change in the roll gap.

On the other hand, if it is determined that the following blank pipe is the same type by comparison of the pipe length and tip temperature with the pre-passing material, the pre-passing material is Arithmetic control is performed based on the above-mentioned actual value of the material and the temperature distribution over the entire length of the raw pipe in front of the diameter sizing machine.

That is, the above-mentioned product type is determined while the blank tube is in the front position of the diameter-sizing machine, and based on this result, the actual value of the outside diameter deviation over the entire length of the material passing through the front is stored in the outside diameter calculation storage device 20. The data is taken into the arithmetic unit 21.

The main processing unit 21 uses the setting information regarding the subsequent blank pipe to calculate the actual value of the preceding material from the outer diameter calculation storage device 20 according to the amount by which the blank pipe should shrink when it is cooled to room temperature, for example. The flow rate is controlled so that the roll gap of the stand to be controlled is gradually increased or decreased in accordance with the temperature distribution measurement value from the temperature distribution generator 18 so that the corrected actual outside diameter deviation disappears over the entire length. valve 12
A control signal is sent to the finished tube, thereby performing drawing finishing over the entire length of the subsequent blank tube with controlled gradual changes in the roll gap so that the outer diameter and roundness of the finished tube after cooling are uniform over the entire length.

Through this control, the temperature distribution and outer diameter distribution of the raw pipe that has passed through the diameter-sizing machine at the rear surface of the diameter-sizing machine are measured in the same way, and actual values are stored in the outer diameter calculation storage device 20 to be used as control information for the next succeeding raw pipe. is temporarily stored as

The control timing in both of the control modes mentioned above is determined by the current of the drive roll of each stand of the sizing machine, the load detector of the J-Syray, the tube speed calculation tracking device, and the passage detector on the front of the sizing machine, so that the tip of the blank tube is controlled. This is done by detecting the point in time when the roll gap reaches the stand, and by this point the roll gap, which has already been initially set to the standard roll gap value by the setting board, is increased or increased in a controlled manner simultaneously with the biting of the blank tube. This means that it will begin to gradually decrease.

In addition, by tracking the tail end of the raw pipe using the above-mentioned tracking device, it is possible to reliably detect that the raw pipe has come out of the stand to be controlled, and this detection signal can be used to set the roll gap of the stand in advance for the next raw pipe. set the standard roll gap value.

In this case, the roll gap is reset before the next blank pipe arrives, but this can usually be done within a few seconds and does not interfere with the work schedule.

As is clear from the explanation of the specific embodiments described above, according to the present invention, the roll gap of the sizing machine can be
Since the control is performed to continuously and gradually change the outer diameter over the entire axial length of the raw pipe, it is possible to manufacture uniform seamless steel pipes with no change in the outer diameter in the axial direction. Since the actual measured outside diameter of the passing material is used as the actual value for proper control of the roll gap of the sizing machine, extremely effective control can be achieved for the production of seamless steel pipes of the same type, and the true Since circularity can also be added to the control information, it is possible to obtain perfectly round products with little difference in outer diameter.

[Brief explanation of drawings]

The drawing is a block explanatory diagram showing a control system according to an embodiment of the present invention. 2...Diameter machine, 3...Passing detector, 6
... Speed detector, 7 ... First temperature detection device, 8 ... Pulse generator, 9 ... Field position detector, 10. ...Load detector, 14.
...Second temperature detection device, 15...Outer diameter detection device, 22.23...Setting panel.

Claims (1)

[Claims] 1. When the axial temperature distribution of the raw tube is measured in front of the diameter-sizing machine, and the raw tube is cooled based on a preset target outer diameter value and the axial temperature distribution. By predictively controlling the outer diameter of the finished tube, the outer diameter of the raw tube is drawn and finished while gradually changing the roll gap of the stand controlled by the diameter-sizing machine so that the outer diameter of the finished tube after cooling becomes uniform in the axial direction. A method for adjusting an outer diameter in a diameter-sizing machine for manufacturing seamless steel pipes. 2. Measure the length and tip temperature of the raw pipe in front of the diameter sizing machine and compare it with the length and tip temperature of the material passing before to determine whether they are of the same type, and if they are not of the same quality, 2. A method for adjusting an outer diameter in a diameter-sizing machine for producing seamless steel pipes according to claim 1, characterized in that the outer diameter of the raw pipe is predictively controlled when it is cooled. 3 Measure the temperature and outer diameter over the entire axial length of the raw pipe that has passed through the diameter sizing machine on the rear surface of the diameter sizing machine, and set the outside diameter distribution over the entire axial length in advance based on the temperature distribution over the entire axial length. The temperature is corrected based on the reference temperature, which is then temporarily stored as the actual value of the material passing through before, and the length and axial temperature distribution of the succeeding pipe are measured in front of the diameter sizing machine, and the measured length and tip temperature are calculated. Based on this, it is determined whether or not the quality is the same as that of the previous passing material, and if they are of the same quality, the amount of outer diameter contraction when the raw pipe is cooled is determined as the target outer diameter at a preset reference temperature. The outside diameter of the finished pipe after cooling is corrected based on the value, and then the outside diameter of the finished pipe after cooling is adjusted to A method for correcting an outer diameter in a diameter-sizing machine for producing seamless steel pipes, the method comprising drawing and finishing the outer diameter of a raw pipe while gradually changing the roll gap of a stand controlled by the diameter-sizing machine so that the diameter is uniform in the direction. 4. Claim 3, characterized in that the measurement of the outer diameter distribution over the entire axial length is performed simultaneously in two mutually perpendicular radial directions of the raw pipe, and the roundness is included in the measurement results. A method for adjusting the outer diameter in a diameter-sizing machine for manufacturing seamless steel pipes as described in . 5 A temperature distribution measuring device that measures the axial temperature distribution of the raw pipe in front of the diameter-sizing machine in which multiple stands to be controlled are arranged in series, a pipe length detection device that detects the length, and a temperature distribution measuring device that measures the temperature distribution in the axial direction of the raw pipe in front of the diameter-sizing machine in which multiple stands to be controlled are arranged in series, and a pipe length detection device that detects the length, and a A roll position detection device is provided to detect the roll gap of the stand, and a tube speed calculation tracking device is provided to detect the insertion and passage of the raw tube into the fixed diameter machine stand, and to track both ends of the raw tube and detect the speed between the stands. A device, a temperature detection device that detects the temperature over the entire length of the raw pipe that has passed through the diameter measuring machine, an outer diameter detection device that detects the outer diameter, and the material, thermal expansion coefficient, and target outer diameter at the reference temperature regarding the raw pipe. Calculate and temporarily store the deviation between the actual measured outer diameter value corrected to the reference temperature and the target outer diameter value over the entire length in the axial direction of the raw pipe based on each setting information such as value and each output information of the temperature detection device and the outer diameter detection device. Based on the above-mentioned setting information and the output information from each of the above-mentioned devices, it is determined whether the raw tube is the same type as the previously passed raw tube, and the outer diameter shrinkage when the raw tube is cooled. After correcting the amount, roll gap control is performed for each stand to be controlled according to the output information from the temperature distribution measuring device if the product is not the same product, or according to the output information from the outer diameter detection device if the product is the same product. 1. An outer diameter correction device for a diameter-sizing machine for producing seamless steel pipes, comprising a main processing unit that issues a control signal to the device to gradually change a roll gap. 6. A passage detector that emits an output when a passed raw tube is present at a predetermined position on the transfer line, a speed detector that detects the transfer speed of the raw tube, and a temperature that detects the temperature over the entire length of the raw tube that is passing through. A first temperature detection device is provided on the front surface of the diameter-sizing machine in which a plurality of stands to be controlled are arranged in series, a roll position detector for detecting the roll gap of the diameter-sizing machine stand, and a revolution counting base tube for detecting the number of roll rotations. A load detector for detecting jamming is installed on the stand of the machine to be controlled, and a second temperature detection device is installed to detect the temperature over the entire length of the raw pipe after passing through the diameter machine, and a second temperature detection device is used to measure the outer diameter. It is equipped with an outer diameter detecting device on the rear surface of the diameter measuring machine, and is further equipped with a pipe length calculator that calculates the length of the blank pipe from the outputs of the passage detector and the speed detector, and a pipe length calculator that calculates the length of the raw pipe from the outputs of the passage detector and the speed detector, and a pipe length calculator that calculates the length of the raw pipe from the outputs of the passage detector and the speed detector, and a pipe length calculator that calculates the length of the raw pipe from the outputs of the passage detector and the speed detector. A temperature distribution generator that stores and outputs the temperature distribution over the entire length of the raw pipe, and tracking of both ends of the raw pipe within the diameter measuring machine based on the fixed stand interval length and the output from the load detector of each controlled stand. A pipe speed calculation tracking device that calculates the raw pipe speed between the stands to be controlled, and a preset material for the raw pipe;
The raw pipe has an actual outer diameter value corrected to the reference temperature based on each setting information of the temperature expansion coefficient, the target outer diameter value at the reference temperature, and each output of the second temperature detection device and the outer diameter detection device and the target outer diameter. An outer diameter calculation storage device that calculates and temporarily stores the deviation over the entire axial length, a reference roll gap set in advance for the raw pipe, a target outer diameter value at a reference temperature, material setting information, and pipe length calculation. Based on the outputs of the chamber temperature distribution generator, roll position detector, tube speed calculator, and outer diameter calculation storage device, it is determined whether the quality of the charged raw tube is the same or not by comparing with the material passed before. After correcting and calculating the amount of outer diameter shrinkage when the raw tube is cooled, if they are not the same type, calculate the total axial length according to the output of the temperature distribution generator, or if they are the same type, calculate the total axial length from the outer diameter calculation storage device. According to the above-mentioned deviation, the main processing unit sends a control signal for gradually changing the roll gap to the roll gap control device of each stand to be controlled, according to the deviation. The outer diameter correction device in the diameter-sizing machine for producing seamless steel pipes according to item 5.