JP2005014092A - Method and apparatus for manufacturing seamless steel tube - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To effectively prevent the generation of inside surface flaws by efficiently supplying chemicals or the like to uniformly adhere to the inside surface of a hollow tube stock when manufacturing a seamless steel tube by elongating. <P>SOLUTION: In a method of manufacturing a seamless steel tube, the chemicals or the like are jetted and supplied to the inside surface of the hollow tube stock with a carrier gas, or the chemicals or the like are jetted and supplied through jetting piping having a jetting port which is situated on the inside surface of one end of the hollow tube stock with the carrier gas when elongating the hollow tube stock and, the chemicals or the like are jetted with the carrier gas which is supplied from the upstream side while discharging the chemicals or the like into the jetting piping so as to adjust the concentration of the chemicals or the like in the carrier gas by revolving the hollow tube stock while securing the airtightness at the end of the jetting side. An apparatus for the method is also disclosed. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  TECHNICAL FIELD The present invention relates to a method and an apparatus for manufacturing a seamless steel pipe for drawing and rolling a hollow shell, and more particularly, to prevent internal flaws that are likely to occur during drawing and rolling, and to use the inner surface lubricant or hollow shell used for that purpose. TECHNICAL FIELD The present invention relates to a method for manufacturing a seamless steel pipe and an apparatus for manufacturing the same, which can minimize the amount of chemicals (hereinafter collectively referred to simply as “medical agents”) for melting or removing the inner scale of the steel. .

  As a method of manufacturing a seamless steel pipe hot, there are a Mannesmann plug mill manufacturing method, a Mannesmann mandrel mill manufacturing method, and a Mannesmann push bench manufacturing method. In these pipe making methods, a process of rolling a hollow shell from a solid round billet that is a raw material by hot rolling to manufacture a seamless steel pipe is employed.

  As a specific manufacturing process, a solid round billet heated to a high temperature of 1150 ° C. to 1250 ° C. is used as a rolling material, and this round billet is fed to a piercing and rolling machine to make a hole in its axial center. To obtain a thick hollow shell. Next, the obtained hollow shell is fed to one or more kinds of drawing and rolling apparatuses, subjected to thickness processing, and drawn and rolled. After that, it is a process of producing a seamless steel pipe that becomes a product through a refining process that performs polishing, shape correction, and sizing through a stretch reducer, reeler, sizer, and the like.

  As typical drawing and rolling mills employed in the above-mentioned pipe making method, there are a second drilling machine, a plug mill and a reeler in the Mannesmann plug mill pipe making method, and a mandrel mill in the Mannesmann mandrel mill pipe making method. Usually, in these drawing and rolling machines, seizure between the tool inserted in the inner surface of the hollow shell and the inner surface of the core tube or internal flaws such as scratches due to the scale of the inner surface of the core tube are likely to occur. For this reason, in order to prevent these inner surface flaws, prior to stretching and rolling, agents that exert a lubricating action and a function of melting or removing the scale, for example, metal salts such as sodium borate or salt, graphite, etc. It may be put into the inner surface of the hollow shell used as the material.

  Conventionally, various methods have been proposed as a method for introducing a drug or the like into the inner surface of a hollow shell. First, in Patent Document 1, as a scale removal method, a scale remover is supplied by compressed gas from one end of a hollow shell, and a residual remover that moves spirally along the inner surface of the hollow shell is sucked from the other end. A method of discharging is proposed.

  In the proposed method, it is difficult to uniformly supply the scale remover to the inner surface of the raw tube, and a lot of chemicals etc. are discharged without being attached to the inner surface of the raw tube due to suction from the other end. Increases significantly. And since a chemical | medical agent etc. cannot adhere to a raw material pipe inner surface, adhesion to a raw material pipe inner surface becomes non-uniform | heterogenous, and it becomes easy to generate | occur | produce an internal flaw. In addition, since the scale remover collected on the suction side is mixed with the raw tube scale and the like, a large amount of capital investment is required to remove these and reuse them.

  Next, in Patent Document 2, as a method of applying the pickling agent to the inner surface of the raw tube, a pickling agent of a predetermined condition is supplied into the pressure vessel, mixed and pressurized with a gas such as air or nitrogen, and then the pressure vessel The pickling agent is applied to the inner surface of the raw pipe while being circulated, turbulent, laminar or pulsating by being led to the discharge device via the open valve provided in the pipe and the subsequent transport pipe.

  In the method disclosed here, it is difficult to uniformly mix the pickling agent and the gas in the pressure vessel. As a result, the pickling agent does not adhere uniformly to the inner surface of the hollow shell. For this reason, it is not sufficient to prevent the generation of inner surface flaws as in the above-described scale removal method.

  Furthermore, in the apparatus for supplying a flowable component to the inner surface of the hollow shell proposed in Patent Document 3, in order to make the adhesion to the inner surface of the blank tube uniform, By providing a configuration that twists the flow of the flowable component and carrier gas mixture, this twisting motion attempts to achieve the objective.

  However, it is difficult to maintain the flow of the mixture as a torsional motion over the entire length with the raw tube dimensions used as the material for the Mannesmann tube manufacturing method and the like, and it is not possible to uniformly attach the flowable components to the inner surface of the raw tube. . Further, since a large amount of gas needs to be used, the components are easily released from the other end side of the raw tube together with the carrier gas. Therefore, even with the proposed apparatus, there is a problem that the generation of internal flaws is not sufficient and the manufacturing cost increases.

JP 60-64720 A Japanese Patent Publication No. 7-74468 Japanese Patent Publication No. 7-71689

  The present invention solves the problems of the above-described conventional method and apparatus for charging the inner surface of a hollow shell, and efficiently supplies the drug, etc. to the inner surface of the hollow shell during drawing and rolling. Provided is a method for manufacturing a seamless steel pipe and an apparatus for manufacturing the same, which can prevent the occurrence of internal flaws caused by stretching and rolling, and minimize the amount of chemicals and the like used for that purpose. The purpose is to do.

The gist of the present invention is the following (1) to (4) seamless steel pipe manufacturing method and the following (5) and (6) seamless steel pipe manufacturing apparatus.
(1) When a hollow shell is drawn and rolled, a lubricant or a chemical for melting or removing the scale on the inner surface of the hollow shell (hereinafter referred to as “medical agent”) is injected by a carrier gas. A method of manufacturing a seamless steel pipe to be charged, in order to prevent a large amount of chemicals or the like from adhering to the distal end side of the raw pipe or from adhering to the proximal end side while injecting and charging the chemical or the like with a carrier gas, Manufacture of seamless steel pipe characterized by jetting with carrier gas supplied from the upstream side while cutting out medicines etc. in the jet pipe so that the jet pressure of the carrier gas can be increased or decreased sequentially Is the method.
(2) A method of manufacturing a seamless steel pipe in which a drug or the like is injected and injected into the inner surface of the hollow shell by a carrier gas when the hollow shell is drawn and rolled, while ensuring airtightness at the injection side end A seamless steel pipe that is injected by a carrier gas supplied from the upstream side while cutting out the medicine in the injection pipe so that the concentration of the medicine in the carrier gas can be adjusted while rotating the hollow shell. It is a manufacturing method.
(3) A method for producing a seamless steel pipe in which a chemical agent or the like is injected and injected by a carrier gas through an injection pipe having an injection port located on one inner surface of one end of the hollow shell when the hollow shell is drawn and rolled. The carrier gas supplied from the upstream side while cutting out the drug etc. in the injection pipe so that the concentration of the drug etc. in the carrier gas can be adjusted while rotating the hollow shell while ensuring the airtightness of the side end It is the manufacturing method of the seamless steel pipe characterized by spraying by.
(4) A method of manufacturing a seamless steel pipe in which a drug or the like is injected and injected into the inner surface of the hollow shell by a carrier gas when the hollow shell is drawn and rolled. A method of manufacturing a seamless steel pipe characterized in that a plurality of translation claws and a skid are provided up to the start position of the next drawing rolling after being injected by gas, and the hollow shell is conveyed while rotating around the pipe axis. is there.
(5) A device for producing a seamless steel pipe by injecting and supplying a chemical or the like to the inner surface of the hollow element pipe with a carrier gas when the hollow element pipe is drawn and rolled. In order to adjust the concentration of the drug etc. in the carrier gas while rotating the hollow shell while ensuring the airtightness of the injection side end, supply the drug from the upstream side while cutting out the drug etc. in the injection pipe An apparatus for producing a seamless steel pipe, characterized in that it is equipped with a device capable of being injected by a carrier gas.
(6) An apparatus for producing a seamless steel pipe by injecting a drug or the like into the inner surface of the hollow element tube with a carrier gas when the hollow element tube is drawn and rolled. An apparatus for producing a seamless steel pipe, characterized in that a raw pipe is provided with a plurality of translation claws and a skid up to the starting position of drawing and rolling, and transported while rotating around a pipe axis.

  According to the method of manufacturing a seamless steel pipe and a manufacturing apparatus using the same according to the present invention, a chemical or the like is efficiently supplied to the inner surface of the hollow shell during the drawing and rolling, thereby uniformly rolling. Generation of internal flaws in the material can be prevented. In addition, the amount of the drug used for that purpose can be minimized, which is effective in reducing the manufacturing cost.

  As described above, in the present invention, during the drawing and rolling, the chemicals and the like are efficiently supplied to the inner surface of the hollow shell and uniformly adhered, thereby preventing internal flaws generated by rolling and using the chemicals and the like. The aim is to minimize the amount. The term “when stretching and rolling” as defined in the present invention includes a case where it is performed prior to stretching and a case where it is performed simultaneously.

  On the other hand, the drug or the like targeted by the present invention is applied to a hollow shell made of various dimensions and materials, but in order to effectively exert a lubricating action and a scale melting or removal action, depending on the pipe material. The quantity and / or type must be selected. If the amount or type of the drug is different, the specific gravity of the drug or the like and its form (particle size, particle shape, etc.) and the flowability resulting from these (for example, ease of clogging in the pipe) are naturally obtained. Will change.

  Therefore, in order to achieve the above-mentioned object efficiently, it is necessary to set the injection condition of the carrier gas based on the dimensions of the hollow shell, the material of the hollow shell, the kind of medicine, and the like. Here, the dimensions of the hollow shell indicate the inner diameter and the length of the blank. Then, the outer diameter of the inner surface tool used for stretching and rolling approximately, for example, the outer diameter of the plug or the outer diameter of the mandrel bar can be used as the inner diameter of the raw tube. Or, instead of finely changing the conditions depending on the tube dimensions and tool dimensions, group the tube dimensions in consideration of the representative outer diameter (rolling setup) of the hollow tube, and the conditions for each group May be determined. As the carrier gas, air, nitrogen gas or the like is used.

  The jetting pressure of the carrier gas needs to be set to a high pressure because the gas passage resistance increases as the length of the tube and the inside diameter of the tube decrease. However, if the set pressure is too high, the chemicals contained in the gas will be discharged from the other end of the raw tube, and the amount of use will increase. On the other hand, if the set pressure is too low, the amount of adhesion to the inner surface of the other end decreases, and there is a concern about the generation of inner surface flaws. Therefore, by setting an appropriate injection pressure in accordance with the dimensions of the hollow shell, it is possible to adhere the medicine or the like to the inner surface of the blank uniformly and without waste.

  Furthermore, by changing the injection flow rate or / and the injection time of the drug etc., it is possible to adjust the adhesion amount of the drug etc. per unit area of the inner surface of the hollow shell even under the same carrier gas injection pressure. is there. Therefore, by appropriately combining the conditions of the injection pressure of the carrier gas, the dosage of the medicine, etc., and the dosage time of the medicine, etc., an appropriate quantity of the medicine, etc. can be supplied without waste and uniformly adhered to the inner surface of the raw tube. Can do.

  FIG. 1 is a diagram for explaining the operation of a rolling information recognition unit, an injection condition determination unit, and an injection condition adjustment unit provided in the apparatus example of the present invention. Of the rolling information, the dimensions of the hollow shell 1 are recognized from manufacturing schedule information held in advance by a process computer or the like or measurement results in the manufacturing line. Similarly, the material of the hollow shell 1 is recognized from manufacturing schedule information held by a process computer or the like, and these data are transmitted to a rolling information recognition unit.

  On the other hand, information about the type of chemicals used for stretching and rolling is also transmitted to the rolling information recognition unit in advance. Furthermore, if necessary, the type of medicine or the like may be transmitted by the operator in advance by operating the device, or automatically selected by a process computer or the like according to the size and material of the hollow shell 1 It is good also as a structure to be made.

  The rolling information transmitted to the rolling information recognizing unit is transmitted to the injection condition determining unit, and the injection conditions that are actually adopted by the set value table or the set value calculation formula prepared in advance, specifically, Determines the injection pressure of the carrier gas, the total amount of the drug or the like, or the charging time of the drug or the like.

  The various injection conditions determined by the injection condition determining unit are transmitted to the injection condition adjusting unit in order to realize the injection conditions, and a specific injection operation is performed. As shown in FIG. 1, in the injection into the hollow shell 1, the medicine or the like is cut out from the carrier supply apparatus 5 to the carrier gas supplied from the carrier gas supply apparatus 6 through the valve 4 to the injection pipe 3. This is done from the injection port 2 provided at the tip of the injection pipe 3.

  The injection conditions determined by the injection condition determination unit are reflected and adjusted as the pressure setting value of the carrier gas tank 6a in the carrier gas supply device 6 and / or the extraction speed and the extraction time in the supply device 5 for medicines and the like. The actual injection work to the hollow shell 1 is performed on the basis of the injection pressure, the total injection amount of the medicine and the like and the injection time.

  Usually, when the injection pressure of the carrier gas is increased, a large amount of medicine or the like adheres to the distal end side (discharge side) of the element tube, and when the injection pressure is decreased, the medicine or the like tends to adhere to the proximal end side. However, in the case of continuously injecting a medicine or the like at a constant injection pressure, the adhesion amount of the medicine or the like may vary in the longitudinal direction of the element pipe due to resistance from the wall surface when gas passes through the inner surface of the element tube. Such non-uniform adhesion in the longitudinal direction of the tube can be eliminated by sequentially increasing or decreasing the carrier gas pressure during the injection operation. Since the amount of adhesion in the longitudinal direction can be changed according to the change in the injection pressure, the result is uniform adhesion.

  Further, the fluctuation of the injection pressure during the injection operation may be increased and then decreased sequentially, or the reverse procedure may be adopted. However, a fluctuation method with a sudden pressure change within a short time, generally called a pulsating flow, should be avoided. This is because a smooth gas flow is hindered by an abrupt pressure change and it is difficult to make the adhesion uniform.

  In order to inject the drug and the carrier gas in a homogeneous mixed state, the rotary blade type cutting mechanism is used to inject the drug or the like while cutting out the drug or the like into the injection pipe through which the gas flows. Efficient. By injecting while cutting out, the concentration of the drug or the like in the carrier gas can be easily changed and can be arbitrarily adjusted from the start to the end of the injection.

  In the application method of the pickling agent disclosed in Patent Document 2, since concentration variation due to gravity of the drug etc. is unavoidable at the time of mixing in the pressure vessel, the drug etc. in the pipe is increased when the concentration of the drug etc. is increased. It is easy to clog, making stable injection difficult.

  FIG. 2 is a diagram illustrating a configuration of a medicine supply device provided with a rotary blade type cutout as an example of the device of the present invention. The white arrow in the injection pipe 3 shown in the figure indicates the flow of only the carrier gas, and the black arrow indicates the flow of mixing of the carrier gas and the medicine. A rotary vane type cutout portion 5b is provided for directly cutting out the drug etc. 5c in the drug etc. tank 5a into the injection pipe 3 through which the carrier gas flows, and the carrier gas is injected upstream of the cutout portion 5b. There is provided a carrier gas supply device (not shown) for charging into the inside.

  The rotary blade type cut-out portion 5b is installed between the medicine tank 5a and the injection pipe 3, and when the blade is rotated by the attached motor M, a predetermined amount of the medicine 5c is continuously cut out in the injection pipe 3. It is. In order to adjust the cut-out amount of the medicine 5c, an encoder can be installed on the rotary blade in order to accurately detect the rotation speed (angle) as the adjusting means.

  The medicine 5c in the medicine tank 5a is cut out into the injection pipe 3 by the rotation of the rotary blades. At this time, the carrier gas is supplied from the upstream side of the injection pipe 3, and the medicine and the carrier gas are supplied at a constant rate. It is mixed and guided to the injection port. By using a carrier gas in a homogeneous mixed state, it is possible to stably inject a drug or the like into the hollow shell.

  By applying the rotary blade type cut-out section, the cut-out amount per unit time becomes a constant value, and the supply of the medicine and the like into the injection pipe through which the carrier gas flows can be stabilized. The supply of the medicine 5c to the medicine tank 5a is performed by the medicine supply pipe 5e, and the pressure supply to the medicine tank 5a is performed by the pressurization pipe 5d. In order to prevent the backflow due to the carrier gas pressure in the cutout part 5b, the tank 5a for the medicine and the operation part of the cutout part 5b can be supplementarily pressurized with the same type of gas as the carrier gas.

  The total amount of medicine and the like is determined from the total number of rotations (angle) of the rotating blades and the individual volumes between the rotating blades, and the cutting speed is determined from the rotating speed of the rotating blades and the individual volumes between the rotating blades. . As described above, it is important to adjust the rotation speed and the rotation time in accordance with the dimensions of the hollow shell, the material, the type of medicine, and the like.

  If the hollow shell is rotated when the drug or the like is sprayed onto the inner surface of the raw tube, it is effective to reduce the variation in the amount of adhesion in the circumferential direction of the inner surface of the raw tube and to make it adhere uniformly. In other words, even when the injection position of the drug or the like deviates from the center of the cross section of the raw tube, the circumferential adhesion is averaged by the rotation of the raw tube, and the influence of the gravity of the drug or the like can be eliminated. The drug attached to the inner surface of the tube is promoted to flow in the circumferential direction by the rotation, and the uniform adhesion and the minimization of the usage amount can be further promoted. The raw tube may be rotated by disposing the raw tube on the rotating roller at a position where a medicine or the like is injected.

  FIG. 3 is a diagram illustrating a configuration in which a raw tube is arranged on a rotating roller as an example of the apparatus of the present invention. The hollow shell 1 is rotated around the tube axis at the position where a medicine or the like is injected and injected, for example, by a rotating roller 1a installed in the tube axis direction during the injection of the medicine or the like. At this time, all the rotation rollers 1a may be rotationally driven, some may be rotationally driven, and others may be freely rotated (idle rollers).

  As shown in FIG. 3, the medicine and the like are injected and injected from one end of the hollow shell 1 toward the other end. However, in order to effectively use the injection pressure, the injection is performed so that the airtightness of the injection side end can be secured. A face plate 2 a covering the side end is installed integrally with the injection port 2. In other words, by preparing the injection port 2 configured integrally with the face plate 2a and rotating the hollow shell while ensuring the airtightness of the injection side end when injecting the medicine or the like, the injection conditions are further stabilized. Thus, variation in the amount of adhesion in the circumferential direction over the entire inner surface of the hollow shell 1 can be eliminated.

  If interference with the injection port 2 becomes a problem when the hollow shell 1 is carried into the injection position, the injection port 2 integrated with the face plate 2a is separated from the hollow base tube 1 before the start of injection. It is possible to adopt a configuration in which it is retracted to the side (right side in the figure), advanced to the raw tube side immediately before the start of injection, and retracted again after the end of injection. At this time, by installing the face plate 2a integrally, the injection port 2 can be positioned at a fixed position with respect to the raw tube, so that the effect of making the injection condition constant can also be obtained.

  As a production line layout, when it is necessary to transport a hollow tube that has been pierced and rolled by a predetermined distance to the start position of the next process of drawing and rolling, the raw material tube that has been charged with chemicals or the like on its inner surface is conveyed Try to rotate around. Thereby, further uniform adhesion can be realized in the circumferential direction of the inner surface of the raw tube.

  Usually, after piercing and rolling, when the raw pipe is transported to the starting position of stretch rolling, the raw pipe is often transported sideways. In this case, a plurality of translation claws are provided to convey the raw tube in the lateral direction, and at the same time, the raw tube is rotated while being in contact with the skid rail, whereby the raw tube is rotated. In order to ensure the above-mentioned effect due to the rotation of the raw tube during transportation, for example, it is sufficient to carry out the rotational transportation for 1 second or more, and to fully adapt the drug etc. to the inner surface of the hollow shell or to react with the scale of the inner surface. It is desirable to give time.

  FIGS. 4A and 4B are diagrams illustrating a configuration in which a plurality of translation claws are provided and a raw tube is conveyed in the lateral direction as an example of the apparatus of the present invention. FIG. 4A is a plan view and FIG. 4B is a side view. ing. As shown in the figure, a plurality of translation claws 7 and skid rails 10 are set in the tube axis direction in parallel with the conveying direction of the hollow shell 1. The interval in the tube axis direction of the installation of the translation claw 7 and the like is appropriately determined according to the length range of the raw tube to be conveyed. In other words, it is necessary to determine an appropriate interval and the number of installed units so that the raw tubes are not conveyed obliquely during the horizontal conveyance.

  As shown in FIG. 4, the translation claw 7 is installed on a chain 8 that is actuated by a sprocket 9 that is rotationally driven. The translation claw 7 moves forward while pressing the side surface of the hollow shell 1 to perform horizontal conveyance of the blank. The number of installed translational claws 7 is appropriately determined depending on the transport distance. For example, even if one translational claw 7 is installed for one chain 8, there is no problem in work, but the cycle time is shortened by shortening the rotation distance of the chain and the failure due to the consumption of related equipment is prevented. From the viewpoint, it is desirable to install a plurality of claws on each individual chain 7.

  On the other hand, the skid rail 10 that is fixedly installed is installed with its upper surface slightly higher than the chain 8, and comes into contact with the lower surface of the hollow shell 1 that is being transported to rotate the shell. In order to prevent wrinkles due to collision between the raw tube surface and the transfer equipment at the start and end of transfer, it is desirable to lower the chain drive speed at the start and end of transfer than during transfer. In addition, it is effective to prevent the above-mentioned conveyance flaws, because the impact received by the blank tube at the conveyance start position and conveyance end position is reduced.

  The effects of the present invention will be described below based on specific examples. The specific conditions described here do not limit the contents of the present invention.

(Example 1)
Using a Mannesmann plug mill pipe line that can produce seamless steel pipes with dimensional specifications of outer diameter: 185.0 to 426.0 mm, wall thickness: 5.0 to 55.0 mm, and length of 5 to 15 m, the second After rolling with a piercing machine and before drawing and rolling with a plug mill in the next step, chemicals and the like were introduced into the inner surface of the hollow shell tube under various conditions to investigate the frequency of occurrence of inner surface flaws in the final product. The chemicals used are a mixture of powder lubricant containing graphite as a main component and salt.

  The medicine supply device has the configuration shown in FIG. 2 and once stores and secures the premixed medicine etc. in the tank, and opens the rotary blade type cutout part at the bottom of the medicine etc. tank in a predetermined time, A drug or the like is cut out in a pipe that leads to the injection port.

  Nitrogen gas is used as the carrier gas, and a predetermined amount of medicine or the like is cut out in the injection pipe through which the gas flows, and the mixed gas is injected from the injection port. Here, the injection pressure of the carrier gas is adjusted by a proportional valve and an accumulator, and the cut-out time of the medicine or the like can be adjusted by the rotation time of the rotary blade type cut-out portion. The injection port is provided at the tip of the injection pipe, and a straight pipe nozzle is attached.

  The materials used for the production of seamless steel pipes were all carbon steel having a C content of about 0.2%. The dimensions of the hollow shell pierced and rolled by the second piercer are: A: inner diameter 200 mm × length 7000 mm, B: inner diameter 300 mm × length 3000 mm, C: inner diameter 300 mm × length 7000 mm, and D: inner diameter 400 mm × length. There were four types of 7000 mm, and the number of specimens under each condition was 20.

The total dosage of drug or the like to the hollow shell inner surface was adjusted to 100 g / m ² or 70 g / m per unit area input of ^2, the inner surface area. The results of investigating the frequency of occurrence of internal flaws in the final product at this time are shown in Table 1 together with the injection conditions of drugs and the like.

From the investigation results shown in Table 1, in the examples of the present invention under conditions 5 to 8, by adjusting the injection pressure of the carrier gas and the charging time of the drug etc. based on the dimensions (A to D) of the hollow shell, Although a small amount of drug or the like is input, it is clear that a more excellent effect of suppressing internal flaws can be obtained.
(Example 2)
In condition 4 of the first embodiment (conventional example), the proportional valve is set so that the injection pressure is 1.5 kg / cm ² (147.1 kPa) at the start of injection and 1.0 kg / cm ² (98.1 kPa) at the end of injection. As a result, the inner surface flaws were not generated with respect to the number of 20 rolled.

Similarly, the proportional pressure was operated to sequentially increase the injection pressure so that the injection pressure was 1.0 kg / cm ² (98.1 kPa) at the start of injection and 1.5 kg / cm ² (147.1 kPa) at the end of injection. However, there was no occurrence of internal defects. From this, it can be seen that the effect of suppressing inner surface flaws is further exhibited by sequentially increasing or decreasing the injection pressure of the carrier gas during the injection operation.

Example 3
In the condition 1 of Example 1 (conventional example), injection was performed while rotating the hollow shell. As a result, the number of inner surface flaws was reduced to one with respect to the number of rolled 20 pieces. By rotating the hollow shell during injection, the generation of inner surface flaws is further prevented.

(Example 4)
After injection of a drug or the like under condition 1 of Example 1, the occurrence of inner surface flaws when the hollow shell was rotated and conveyed was investigated. The conveyance speed at this time was about 1.5 m / sec, and the conveyance time was 7 sec. As a result, the number of inner surface flaws is reduced to one with respect to the number of 20 rolled, and the effect of rotating the hollow shell during the conveyance is clear.

  According to the method of manufacturing a seamless steel pipe and a manufacturing apparatus using the same according to the present invention, a chemical or the like is efficiently supplied to the inner surface of the hollow shell during the drawing and rolling, thereby uniformly rolling. It is possible to prevent internal flaws of the material. In addition, the amount of the drug used for that purpose can be minimized, which is effective in reducing the manufacturing cost. For this reason, it can apply widely as an efficient supply means, such as a chemical | medical agent, in the case of manufacture of a seamless steel pipe.

It is a figure explaining the effect | action of the rolling information recognition part, the injection condition determination part, and the injection condition adjustment part which were equipped in the example of the apparatus of this invention. It is a figure explaining the structure of the supply apparatus of the chemical | medical agent etc. which provided the rotary blade type | formula cutout part as an example of an apparatus of this invention. It is a figure explaining the structure which arrange | positions a raw tube on a rotating roller as an example of an apparatus of this invention. It is a figure explaining the structure which provides a some translating claw as an example of an apparatus of this invention, and conveys a raw tube to a horizontal direction, (a) shows a top view, (b) has shown the side view.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1: Hollow hollow tube, 1a: Rotating roller 2: Injection port, 2a: Face plate 3: Injection piping, 4: Valve 5: Drug supply apparatus, 5a: Drug tank 5b: Cutting part, 5c: Drug etc. 5d: Addition Pressure pipe, 5e: Drug supply pipe 6: Carrier gas supply device 6a: Carrier gas tank 7: Translation claw, 8: Chain 9: Sprocket, 10: Skid rail

Claims (6)

When drawing and rolling a hollow shell, a lubricant or a chemical for melting or removing the scale on the inner surface of the hollow tube (hereinafter referred to as “medical agent”) is injected and injected with a carrier gas. A method of manufacturing a steel-free pipe,
While injecting and injecting the medicine etc. with the carrier gas, in order to prevent the medicine etc. from adhering to the distal end side or the base end side of the element tube, the carrier gas injection pressure is sequentially increased or sequentially increased. A method for producing a seamless steel pipe, characterized in that the carrier gas supplied from the upstream side is ejected while cutting out the medicine or the like into the ejection pipe so that the amount can be reduced. When drawing and rolling a hollow shell, a method for producing a seamless steel pipe in which a drug or the like is injected into the inner surface of the hollow shell with a carrier gas,
The carrier gas supplied from the upstream side while cutting out the medicine etc. in the injection pipe so that the concentration of the medicine etc. in the carrier gas can be adjusted while rotating the hollow shell while ensuring the airtightness of the injection side end A method of manufacturing a seamless steel pipe, characterized by being injected by When drawing and rolling a hollow shell, a method for producing a seamless steel pipe in which a drug or the like is injected and injected by a carrier gas through an injection pipe having an injection port located on one end inner surface of the hollow shell,
A carrier supplied from the upstream side while cutting out the drug etc. in the injection pipe so that the concentration of the drug etc. in the carrier gas can be adjusted while rotating the hollow shell while ensuring the airtightness of the injection side end A method for producing a seamless steel pipe, characterized by being injected by gas. When drawing and rolling a hollow shell, a method for producing a seamless steel pipe in which a drug or the like is injected into the inner surface of the hollow shell with a carrier gas,
After injection and injection of a drug or the like into the inner surface of the hollow shell with a carrier gas, a plurality of translation claws and skids are provided up to the start of the next drawing and rolling, and the hollow shell is conveyed while rotating around the tube axis. A method for producing a seamless steel pipe characterized by An apparatus for producing a seamless steel pipe by injecting a drug or the like into the inner surface of the hollow shell with a carrier gas when the hollow shell is drawn and rolled,
When injecting the medicine or the like with the carrier gas, the concentration of the medicine or the like in the carrier gas can be adjusted while rotating the hollow shell while ensuring the airtightness of the injection side end. An apparatus for producing a seamless steel pipe, comprising a device capable of injecting with a carrier gas supplied from an upstream side while cutting out a medicine or the like. An apparatus for producing a seamless steel pipe by injecting a drug or the like into the inner surface of the hollow shell with a carrier gas when the hollow shell is drawn and rolled,
A seamless steel pipe characterized by comprising a device for transporting a hollow shell in which a chemical agent or the like is injected into the inner surface thereof, provided with a plurality of translation claws and a skid to the starting position of stretching and rolling and rotating around the pipe axis. Manufacturing equipment.

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