JP2009195988A - Method and apparatus for controlling rolling, control program of mandrel mill and seamless tube - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method or the like for controlling rolling by which a tube stock (a part such as end parts or the entire length of the tube stock) is rolled into desired wall-thickness accurately and also the surface properties of the tube stock are not deteriorated. <P>SOLUTION: In this method for controlling the rolling of the mandrel mill, when rolling the tube stock S in a finishing stand #i of respective stands comprising the mandrel mill M, the screw-down location of first caliber rolls arranged in the finishing stand #i is varied outward, when rolling the tube stock in the nearest upstream stand #i-2 the screw-down direction of which is the same as that of the finishing stand #i, the screw-down location of a second caliber rolling rolls arranged in the upstream stand #i-2 is also varied outward. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a rolling control method capable of accurately rolling a raw pipe (a part or the entire length of an end of the raw pipe) to a desired thickness in a mandrel mill used for manufacturing a seamless pipe. , A rolling control device, a control program, and a seamless pipe.

  In the manufacture of seamless pipes by the Mannesmann-Mandrel mill method, first, a round billet or square billet of a material is heated to 1200 to 1260 ° C. in a rotary hearth heating furnace, and then pierced and rolled with a plug and a rolling roll with a piercing machine. To manufacture hollow shells. Next, a mandrel bar is inserted into the inner surface of the hollow shell in a skewer shape, and the outer surface is normally constrained by a perforated rolling roll with a mandrel mill consisting of 5 to 8 stands, thereby extending to a predetermined thickness. Reduce meat. Then, after extracting the mandrel bar, the thinned tube is shaped and rolled to a predetermined outer diameter with a drawing mill to obtain a product.

  In addition, as a mandrel mill, a pair of perforated rolling rolls opposed to each stand has been conventionally arranged, and a two-roll mandrel mill in which the rolling roll reduction direction is shifted by 90 ° between adjacent stands and arranged alternately. Is often used. In addition, a four-roll type mandrel mill in which four roll-type rolling rolls having an angle of 90 ° in the rolling direction are disposed on each stand is applied in part, and the angle formed in the rolling direction in each stand A three-roll mandrel mill is also proposed in which three perforated rolling rolls with a 120 ° are disposed and are alternately arranged with the rolling rolls being shifted by 60 ° between adjacent stands.

  Here, in the drawing mill, it is known that a thinning phenomenon occurs in which the thickness of the end portion of the raw tube becomes thinner than that of the central portion, particularly when the raw tube to be rolled is thick. Therefore, a rolling control method has been proposed in which the end of the pipe is increased in the mandrel mill in the previous process in order to offset the thinning phenomenon of the end of the pipe that occurs in such a drawing mill (for example, a patent Reference 1).

  More specifically, in the rolling control method described in Patent Document 1, when the end of the raw tube passes through a finishing stand of a mandrel mill or the like, This is a method of setting the gap of the perforated rolling rolls arranged on the finishing stand or the like by an amount that can offset the thinning amount (see claim 1, paragraph 0012 of Patent Document 1).

  However, when the inventors of the present invention actually carried out a rolling test according to the method described in Patent Document 1, it was impossible to accurately roll the end of the blank to the desired thickness, and the surface of the blank It was found that the properties may deteriorate.

  On the other hand, if a configuration (for example, see Patent Document 2) in which the gap opening amount is adjusted in accordance with the actual tube thickness on the outlet side of the mandrel mill, it can be accurately rolled to a desired thickness. I can expect that. That is, for example, when the actual tube thickness measured on the outlet side of the mandrel mill measured with a wall thickness meter is smaller than the desired wall thickness, the gap opening amount is increased according to the difference. If adjusted (that is, if the rolling position of the perforated rolling roll is changed outward), it can be expected that the thickness accuracy can be improved.

  However, when the inventors of the present invention actually carried out a rolling test based on such an idea, the gap opening amount increased without limit (the hole-type rolling roll fluctuated infinitely outward), and desired It has been found that the thickness may not be obtained.

JP-A-6-190406 JP-A-8-71616

  The present invention has been made to solve the problems of the prior art, and in a mandrel mill used for the production of a seamless pipe, a pipe (a part or the entire length of the end of the pipe, etc.) is desired. It is an object of the present invention to provide a rolling control method, a rolling control device, a control program, and a seamless pipe that can be accurately rolled to a wall thickness that does not deteriorate the surface properties of the raw pipe.

  In order to solve the above-mentioned problem, the inventors of the present invention first made extensive studies on the cause of the case where the raw tube cannot be accurately rolled to the desired thickness or the surface properties are deteriorated by the method described in Patent Document 1. . As a result, in general, in a finishing stand (a stand in which a holed rolling roll that is in contact with a part where the circumferential position of the tube is the same is disposed), a holed rolling roll is used to improve the surface properties of the tube. However, when the gap between the perforated rolling rolls arranged in the finishing stand is opened (that is, when the rolling position is changed outward), the reduction amount is reduced with respect to the finishing stand. If the rolling position of the perforated rolling roll disposed on the stand (upstream stand) located upstream in the conveying direction of the steel tube is not adjusted (if it remains at the initially set rolling position), it will be described later. It has been found that the phenomenon of “groove bottom unrolled” may occur.

  Here, “groove bottom unrolled” means that the thickness of the groove bottom of the blank tube on the inlet side of the finishing stand (thickness of the portion facing the groove bottom of the perforated rolling roll) is the mandrel bar and hole type in the finishing stand. As a result of being smaller than the gap with the rolling roll, it means that the sheet is not rolled on the finishing stand (unrolled).

  Hereinafter, the reason why such “groove bottom unrolling” occurs will be described. When rolling the plate material, the reduction direction is only one direction perpendicular to the plate material, so the gap between the rolling rolls arranged in the upstream stand ≧ the gap between the rolling rolls arranged in the downstream stand If it sets, a board | plate material will not be unrolled with the rolling roll arrange | positioned by the downstream stand. However, in the mandrel mill that rolls the raw material pipe, the position where the raw pipe is squeezed between adjacent stands (holes) in any of the above-described two-roll type, three-roll type and four-roll type. The position of the groove bottom of the die rolling roll is different in the circumferential direction, and not only the thickness of the portion facing the groove bottom of the hole rolling roll, but also the flange portion of the hole rolling roll to which no rolling force is directly applied The thickness of the portion facing the surface is also reduced to some extent. Since the portion facing the flange portion is a portion to which no rolling force is directly applied, it is difficult to control the amount of thinning, and the value can only be predicted to some extent. If there is a deviation in the prediction of the thinning amount (the thinning amount becomes larger than expected), even if the gap between the perforated rolling rolls installed in the upstream stand is equal to the downstream stand (finishing stand). Even if it is set as a gap between the provided rolling mill rolls, a portion with a large thickness reduction facing the flange section of the rolling mill roll in the upstream stand is rolled at the groove bottom of the finishing mill roll roll. In this case, the thickness may be smaller than the gap between the mandrel bar and the perforated rolling roll, which causes the above-mentioned “groove bottom unrolled”.

  When such “groove bottom non-rolling” occurs, the raw tube cannot be accurately rolled to a desired thickness in the finishing stand. In other words, the thickness of the flange portion of the perforated rolling roll disposed in the upstream stand is excessively thinned to the extent that it is not rolled in the finishing stand. The wall thickness of the tube will be thinner than desired. In addition, the original purpose of the finishing stand is to gently finish the inner and outer surfaces of the raw tube by light reduction (by setting the reduction amount small), but when “groove bottom unrolled” occurs, Since it will not be squeezed, surface properties will deteriorate.

  As described above, the inventors of the present invention have the phenomenon that “the groove bottom is not rolled” is the cause when the raw tube cannot be accurately rolled to a desired thickness or the surface properties are deteriorated. And further intensively studied a method for preventing such “groove bottom unrolling” from occurring. As a result, it has been found that “groove bottom unrolling” can be prevented by changing not only the perforated rolling rolls disposed on the finishing stand but also the perforated rolling rolls disposed on the upstream stand in the same manner. The present invention has been completed based on such findings.

  That is, according to the first aspect of the present invention, as described in claim 1 of the present invention, the first pipe disposed on the finishing stand when rolling the blank tube on the finishing stand among the stands constituting the mandrel mill. A rolling control method of a mandrel mill that changes the reduction position of the perforated rolling roll to the outside when the raw pipe is rolled in the nearest upstream stand having the same reduction direction as the finishing stand. The rolling control method of the mandrel mill is characterized in that the reduction position of the second perforated rolling roll disposed on the outside is also changed outward as in the first perforated rolling roll.

  According to such an invention, when rolling the raw pipe in the nearest upstream stand that has the same rolling reduction direction as the finishing stand, the rolling position of the second perforated rolling roll disposed in the upstream stand is also the first. It is made to fluctuate outward as in the case of No. 1 punching roll. In other words, even when rolling the raw pipe in a stand located upstream of the finishing stand by two stands, the reduction position of the second perforated rolling roll disposed in the stand is set to the first perforated type. Like the rolling roll, it will be changed outward. Therefore, since the amount of reduction at the bottom of the groove when rolling the raw tube with the second hole rolling roll is reduced, the portion of the portion facing the flange portion of the hole rolling roll disposed on the next stand is thereby reduced. The thickness is not excessively reduced, and as a result, “groove bottom unrolled” does not occur when rolling with the first perforated rolling roll disposed in the next finishing stand. Thereby, while being able to roll an element pipe to desired wall thickness accurately, the outstanding advantage that the surface property of an element pipe is not deteriorated is acquired. In addition, “changes outward like the first hole-type rolling roll” means that the reduction position of the first hole-rolling roll is changed outward about a part of the end portion of the raw tube. In this case, the reduction position of the second hole-type rolling roll is also changed outward with respect to a corresponding part such as an end of the raw pipe, and the reduction position of the first hole-type rolling roll is extended over the entire length of the raw pipe. When changing outward, it means that the reduction position of the second perforated rolling roll is also changed outward over the entire length of the raw tube. In the present specification, the phrase “change outward as in the case of the first perforated rolling roll” is used in the same meaning.

  In the invention, the second hole is formed in accordance with the position (front end, center, rear end) of the raw tube rolled in the upstream stand (the nearest upstream stand having the same rolling direction as the finishing stand). Although applicable to a mandrel mill having a mechanism capable of changing the rolling position of the die rolling roll, some mandrel mills do not have the above mechanism except for a finishing stand. For such a mandrel mill, the reduction position is not changed in accordance with the position of the raw pipe, but it may be changed outward before rolling the raw pipe.

That is, in order to solve the above-mentioned problems, the present invention provides a first perforated rolling roll disposed on the finishing stand when rolling the blank tube on the finishing stand among the stands constituting the mandrel mill. A rolling control method of a mandrel mill in which the rolling position is changed outward, wherein the rolling position of the second perforated rolling roll disposed in the nearest upstream stand having the same rolling direction as the finishing stand It is also provided as a mandrel mill rolling control method (second rolling control method) characterized in that it is changed outward before rolling.

  Moreover, in order to solve the said subject, when rolling an element pipe in a finishing stand among each stand which comprises a mandrel mill, this invention is the 1st hole-type rolling roll arrange | positioned at the said finishing stand. A rolling control method of a mandrel mill that varies the reduction position outward, and a thickness meter for measuring the thickness of the raw tube along the reduction direction of each stand is disposed on the exit side of the finishing stand, Compare the target wall thickness set in advance on the finishing stand with the actual wall thickness measured by the wall gauge, and if the actual wall thickness is smaller than the target wall thickness Also, the rolling control method (third rolling control method) of the mandrel mill is characterized in that the rolling position fluctuation of the first hole-type rolling roll is interrupted for the raw tube to be rolled next time.

  According to such an invention, a wall thickness meter is arranged on the exit side of the finishing stand, and the target thickness of the raw tube preset in the finishing stand and the actual wall thickness of the raw tube measured by the wall thickness meter are obtained. Will be compared. Here, as a result of the comparison, if the actual thickness is smaller than the target thickness, “groove bottom unrolled” may have occurred. In the present invention, in such a case, it is determined that “groove bottom unrolled” has occurred uniformly, and the rolling position fluctuation of the first hole-type rolling roll is interrupted for the raw pipe to be rolled next time. It is configured. Accordingly, for the raw tube to be rolled next time, the outward movement of the first hole-type rolling roll is interrupted, so the reduction amount of the first hole-type rolling roll does not decrease, and “ It is possible to prevent “groove bottom unrolling”.

In addition, the above-mentioned “interrupting the rolling position fluctuation of the first roll-type rolling roll” is used to mean including the following two cases (1) and (2). That is,
(1) The outward fluctuation amount of the first perforated rolling roll is set to a preset value regardless of the actual wall thickness measured by the wall thickness meter. In this case, “interrupting the rolling position fluctuation” means (a) when rolling a part (end part, etc.) of the raw pipe and when rolling the remaining part (center part, etc.) of the raw pipe. This means that the same reduction position is maintained, or (b) the same reduction position as the reduction position of the first perforated rolling roll for the raw pipe rolled this time.
(2) Although the amount of fluctuation to the outside of the first perforated rolling roll is set in advance, the set value is changed according to the actual thickness measured by the thickness gauge (the actual thickness is more If the thickness is larger than the target wall thickness, the amount of change is set to a smaller value by the difference, and the result is applied to the raw tube to be rolled next time. In this case, “Suspend variation in rolling position” means that the change of the set value according to the actual wall thickness measured by the wall thickness gauge is interrupted, and the next setting for the raw pipe to be rolled next is the same. This means that the number of the one-hole rolling roll is changed.

  In particular, when adopting a configuration in which the set amount of variation to the outside of the first perforated rolling roll is changed according to the actual wall thickness measured by the wall thickness gauge, the “groove bottom unrolled” occurs and the target When the actual wall thickness becomes smaller than the wall thickness, as described above (paragraph 0008), there is a problem that the perforated rolling roll is varied infinitely outward. However, according to the present invention, the outward fluctuation of the first perforated rolling roll is interrupted as in (2) above (the change of the set value according to the actual wall thickness measured by the thickness gauge is interrupted). Therefore, it is possible to solve such a problem.

  In addition, although the said invention is the structure which judges presence or absence of generation | occurrence | production of "groove bottom unrolled" by comparing a target wall thickness with a track record wall thickness, it replaces with this and is the reduction of the 1st hole-type rolling roll. When the amount of change in position is compared with the amount of change in the actual wall thickness along the direction of change of the first punched roll of the tube measured by the wall thickness gauge, if the amount of change is smaller than the amount of change, It is also possible to adopt a configuration in which it is determined that “groove bottom unrolled” has occurred. In other words, when the amount of change is smaller than the amount of change, the groove bottom of the first perforated rolling roll after fluctuation of the reduction position does not come into contact with the outer peripheral surface of the blank tube, and “groove bottom unrolled” In such a case, it is possible to adopt a configuration in which it is determined that “groove bottom unrolled” is uniformly generated.

That is, according to the present invention , when rolling the blank tube in the finishing stand among the stands constituting the mandrel mill, the reduction position of the first perforated rolling roll disposed on the finishing stand is changed outward. A mandrel mill rolling control method, wherein a thickness meter for measuring the thickness of the raw pipe is disposed on the exit side of the finishing stand, and the amount of variation in the reduction position of the first perforated rolling roll, Compared with the amount of change in actual wall thickness along the direction of fluctuation of the first hole-type rolling roll of the tube measured by the wall thickness meter, if the amount of change is smaller than the amount of fluctuation, the next rolling It is also provided as a mandrel mill rolling control method (fourth rolling control method) characterized in that the rolling position fluctuation of the first hole-type rolling roll is interrupted for the raw pipe.

  Further, after comparing the target wall thickness with the actual wall thickness, instead of the configuration for determining whether or not “groove bottom unrolled” has occurred, after the fluctuation of the first perforated rolling roll for the unrolled pipe this time The difference between the rolling position of the first rolling mill roll and the rolling position after fluctuation of the first rolled roll for the previously rolled raw pipe was calculated, and the thickness measured with the wall thickness meter for the current rolled raw pipe The actual wall thickness along the fluctuation direction of the first perforated rolling roll and the actual wall thickness along the fluctuation direction of the first perforated rolling roll measured by the wall thickness meter for the previously rolled raw tube The difference is calculated, and the difference in the rolling position is compared with the difference in the actual wall thickness. If the difference in the actual wall thickness is smaller than the difference in the rolling position, “groove bottom unrolled” occurs. It is also possible to adopt a configuration for judging that. In other words, when the difference in the actual wall thickness is smaller than the difference in the rolling position, the groove bottom of the first roll-type roll after the rolling position change and the outer peripheral surface of the blank tube are in contact with each other for the current rolling. In such a case, it is possible to adopt a configuration that uniformly determines that “groove bottom unrolled” has occurred. .

  That is, according to the present invention, when rolling the blank tube in the finishing stand among the stands constituting the mandrel mill, the reduction position of the first perforated rolling roll disposed on the finishing stand is changed outward. A mandrel mill rolling control method, wherein a wall thickness meter for measuring a wall thickness of the raw pipe is disposed on the exit side of the finishing stand, and the first perforated rolling roll for the raw pipe rolled this time is provided. While calculating the difference between the rolling position after the fluctuation and the rolling position after the fluctuation of the first perforated rolling roll with respect to the previously rolled blank, the thickness was measured with the wall thickness meter for the blank rolled this time. The actual wall thickness along the fluctuation direction of the first perforated rolling roll, and the actual wall thickness along the fluctuation direction of the first perforated rolling roll measured with the wall thickness meter for the previously rolled raw tube. The difference between the reduction positions is calculated Comparing with the difference in the actual wall thickness, if the difference in the actual wall thickness is smaller than the difference in the reduction position, the reduction in the reduction position of the first perforated rolling roll is interrupted for the raw tube to be rolled next time. This is also provided as a mandrel mill rolling control method (fifth rolling control method).

  Moreover, in order to solve the said subject, when rolling an element pipe in a finishing stand among each stand which comprises a mandrel mill, this invention is the 1st hole-type rolling roll arrange | positioned at the said finishing stand. A rolling control method of a mandrel mill that varies the reduction position outward, and a thickness meter for measuring the thickness of the raw tube along the reduction direction of each stand is disposed on the exit side of the finishing stand, Compare the target wall thickness set in advance on the finishing stand with the actual wall thickness measured by the wall gauge, and if the actual wall thickness is smaller than the target wall thickness In the upstream stand that is positioned in the immediate vicinity of the finishing stand and has the same rolling direction as the wall thickness measurement direction in which the actual wall thickness is smaller, when rolling the raw tube to be rolled next time, A second disposed on the upstream stand The reduction position of the perforated rolling roll was also changed outward as in the case of the first perforated rolling roll, or the result was that the actual wall thickness was smaller than the finishing stand. The reduction position of the second perforated rolling roll disposed on the upstream stand having the same reduction direction as the wall thickness measurement direction is previously changed outward before rolling the raw tube to be rolled next time. And a rolling control method (sixth rolling control method) of the mandrel mill.

  According to such an invention, a wall thickness meter is arranged on the exit side of the finishing stand, and the target thickness of the raw tube preset in the finishing stand and the actual wall thickness of the raw tube measured by the wall thickness meter are obtained. Will be compared. Here, as a result of the comparison, when the actual thickness is smaller than the target thickness, “groove bottom unrolled” may occur in the thickness measurement direction. In the present invention, in such a case, it is determined that “groove bottom unrolled” is uniformly generated, and (1) the result is that the actual wall thickness is smaller than that of the finishing stand. In the upstream stand having the same rolling direction as the thickness measuring direction, when rolling the raw tube to be rolled next time, the rolling position of the second perforated rolling roll disposed on the upstream stand is also outward. Or (2) a second disposed on the upstream stand that is located in the immediate vicinity of the finishing stand and has the same rolling-down direction as the thickness measuring direction in which the result thickness is smaller. The rolling position of the perforated rolling roll is previously changed outward before rolling the raw tube to be rolled next time.

  Therefore, in any of the cases (1) and (2) above, the upstream pipe having the same rolling direction as the direction in which it is determined that the “groove bottom unrolling” has occurred, Since the amount of reduction at the stand is reduced and the thickness of the raw tube in the reduction direction is increased, it is possible to prevent “groove bottom unrolling” when rolling at the finishing stand. In addition, the structure of said (1) is a mechanism which can fluctuate the reduction position of a 2nd hole-type rolling roll according to the position (a front-end | tip part, a center part, a rear-end part) of the raw tube rolled in an upstream stand. It is suitably applied to a mandrel mill equipped with The configuration (2) is preferably applied to a mandrel mill that does not include the above-described mechanism except for a finishing stand.

  In addition, although the said invention is the structure which judges presence or absence of generation | occurrence | production of "groove bottom unrolled" by comparing a target wall thickness with a track record wall thickness, it replaces with this and is the reduction of the 1st hole-type rolling roll. When the amount of change in position is compared with the amount of change in the actual wall thickness along the direction of change of the first punched roll of the tube measured by the wall thickness gauge, if the amount of change is smaller than the amount of change, It is also possible to adopt a configuration in which it is determined that “groove bottom unrolled” has occurred.

  That is, according to the present invention, when rolling the blank tube in the finishing stand among the stands constituting the mandrel mill, the reduction position of the first perforated rolling roll disposed on the finishing stand is changed outward. A mandrel mill rolling control method, wherein a thickness meter for measuring the thickness of the raw pipe is disposed on the exit side of the finishing stand, and the amount of variation in the reduction position of the first perforated rolling roll, Compared with the amount of change in actual wall thickness along the fluctuation direction of the first hole-type rolling roll of the raw pipe measured with the wall thickness gauge, and when the amount of change is smaller than the amount of fluctuation, In the upstream stand located in the immediate vicinity of the finishing stand and having the same rolling direction as the wall thickness measuring direction, the second hole rolling provided in the upstream stand is performed when the raw tube to be rolled next time is rolled. The roll reduction position is also the first hole pressure. Like the roll, it is varied outward or the second roll rolling roll placed on the upstream stand located in the immediate vicinity of the finishing stand and having the same rolling direction as the thickness measuring direction. It is also provided as a mandrel mill rolling control method (seventh rolling control method) characterized in that the position is previously changed outward before rolling the raw tube to be rolled next time.

  Further, after comparing the target wall thickness with the actual wall thickness, instead of the configuration for determining whether or not “groove bottom unrolled” has occurred, after the fluctuation of the first perforated rolling roll for the unrolled pipe this time The difference between the rolling position of the first rolling mill roll and the rolling position after fluctuation of the first rolled roll for the previously rolled raw pipe was calculated, and the thickness measured with the wall thickness meter for the current rolled raw pipe The actual wall thickness along the fluctuation direction of the first perforated rolling roll and the actual wall thickness along the fluctuation direction of the first perforated rolling roll measured by the wall thickness meter for the previously rolled raw tube The difference is calculated, and the difference in the rolling position is compared with the difference in the actual wall thickness. If the difference in the actual wall thickness is smaller than the difference in the rolling position, “groove bottom unrolled” occurs. It is also possible to adopt a configuration for judging that.

  That is, according to the present invention, when rolling the blank tube in the finishing stand among the stands constituting the mandrel mill, the reduction position of the first perforated rolling roll disposed on the finishing stand is changed outward. A mandrel mill rolling control method, wherein a wall thickness meter for measuring a wall thickness of the raw pipe is disposed on the exit side of the finishing stand, and the first perforated rolling roll for the raw pipe rolled this time is provided. While calculating the difference between the rolling position after the fluctuation and the rolling position after the fluctuation of the first perforated rolling roll with respect to the previously rolled blank, the thickness was measured with the wall thickness meter for the blank rolled this time. The actual wall thickness along the fluctuation direction of the first perforated rolling roll, and the actual wall thickness along the fluctuation direction of the first perforated rolling roll measured with the wall thickness meter for the previously rolled raw tube. The difference between the reduction positions is calculated Compared with the difference in the actual wall thickness, if the difference in the actual wall thickness is smaller than the reduction position, it is located in the immediate vicinity of the finishing stand and has the same reduction direction as the thickness measurement direction. In the upstream stand, when rolling the raw tube to be rolled next time, the reduction position of the second perforated rolling roll disposed in the upstream stand also fluctuates outward as in the first perforated rolling roll. Or a raw tube for rolling next time the reduction position of the second perforated rolling roll disposed in the upstream stand that is positioned in the immediate vicinity of the finishing stand and has the same reduction direction as the thickness measurement direction It is also provided as a mandrel mill rolling control method (eighth rolling control method), which is previously changed outward before rolling.

  In addition, as described in Claim 2 of this invention, this invention is the 1st for adjusting the rolling-down position of the hole-type rolling roll arrange | positioned in the finishing stand among each stand which comprises a mandrel mill. A rolling position adjusting device, a second rolling position adjusting device for adjusting the rolling position of a perforated rolling roll disposed in the nearest upstream stand having the same rolling direction as the finishing stand, and the first A rolling control apparatus comprising: a rolling control apparatus for instructing a rolling position adjustment amount of the perforated rolling roll to the rolling position adjustment apparatus and the second rolling position adjustment apparatus, wherein the calculation control apparatus comprises: The rolling control according to claim 1, by instructing a predetermined reduction position adjustment amount to the first reduction position adjustment device and the second reduction position adjustment device based on a current position of the raw pipe. Implementing the method It is provided as a rolling control apparatus for a mandrel mill, characterized.

  Further, the present invention provides a reduction position adjusting device for adjusting a reduction position of a perforated rolling roll disposed in a finishing stand among the stands constituting the mandrel mill, and a hole for the reduction position adjustment device. A rolling control device including a calculation control device for instructing a reduction position adjustment amount of the die rolling roll, wherein the calculation control device is disposed on the exit side of the finishing stand and extends along the rolling direction of each stand. 3 to 5 by connecting to a thickness gauge for measuring the thickness of the raw pipe, and instructing the reduction position adjustment device to interrupt the reduction position adjustment based on the output of the thickness gauge. The present invention is also provided as a rolling control device for a mandrel mill characterized by implementing any one of the rolling control methods.

  Furthermore, the present invention provides a first reduction position adjusting device for adjusting a reduction position of a perforated rolling roll disposed in a finishing stand among the stands constituting the mandrel mill, and the finishing stand and the reduction direction. , The second reduction position adjusting device for adjusting the reduction position of the perforated rolling roll disposed in the nearest upstream stand, the first reduction position adjusting device, and the second reduction position adjustment. A rolling control device including a calculation control device for instructing an adjustment amount to the device, wherein the calculation control device is arranged on the exit side of the finishing stand and is arranged along the rolling direction of each stand. By connecting to a wall thickness gauge that measures the wall thickness of the pipe and instructing the second adjustment position adjusting device to a predetermined adjustment amount based on the output of the wall thickness gauge and the current position of the raw pipe , Any of 6th to 8th It is provided as a rolling control apparatus for a mandrel mill which comprises carrying out the rolling control method.

  According to the present invention, as described in claim 3 of the claims, the first for adjusting the reduction position of the perforated rolling roll disposed in the finishing stand among the stands constituting the mandrel mill. And a second reduction position adjusting device for adjusting the reduction position of the perforated rolling roll disposed in the nearest upstream stand having the same reduction direction as the finishing stand, A control program for operating an arithmetic control device for instructing a reduction position adjustment amount of a perforated rolling roll to the first reduction position adjustment device and the second reduction position adjustment device, wherein The rolling control method according to claim 1 is carried out by instructing a predetermined reduction position adjustment amount to the first reduction position adjustment device and the second reduction position adjustment device based on a position. To the above It is also provided as a control program, characterized in that to operate the calculation control device.

  The present invention also provides a reduction position adjusting device for adjusting the reduction position of the perforated rolling roll provided in the finishing stand among the respective stands constituting the mandrel mill, and provided on the exit side of the finishing stand. Connected to a wall thickness gauge that measures the thickness of the raw pipe along the rolling direction of each stand, and operates an arithmetic control device that instructs the rolling position adjustment amount of the rolling roll to the rolling position adjustment device. A control program for causing the rolling position adjustment device to instruct the rolling position adjustment device to interrupt the rolling position adjustment based on the output of the thickness gauge, so that any one of the third to fifth rolling control methods is provided. It is also provided as a control program characterized by operating the arithmetic and control unit so as to implement

  The present invention also provides a first reduction position adjusting device for adjusting a reduction position of a perforated rolling roll disposed in a finishing stand among the stands constituting the mandrel mill, and the finishing stand and the reduction direction. A second reduction position adjusting device for adjusting the reduction position of the perforated rolling roll provided in the nearest upstream stand having the same length, and a reduction direction of each stand provided on the exit side of the finishing stand. For operating an arithmetic and control unit that is connected to a wall thickness gauge that measures the thickness of the raw pipe along the line and that instructs an adjustment amount to the first reduction position adjustment device and the second reduction position adjustment device The control program of the sixth to eighth, by instructing a predetermined adjustment amount to the second reduction position adjustment device based on the output of the thickness gauge and the current position of the raw tube, Either rolling control method It is also provided as a control program characterized by operating the arithmetic and control unit in Hodokosuru so.

  Furthermore, the present invention is also provided as a seamless pipe manufactured by using a mandrel mill in which the rolling control method according to claim 1 is performed as described in claim 4 of the claims. Is done.

  According to the present invention, when rolling the blank tube in the nearest upstream stand whose rolling direction is the same as that of the finishing stand, the rolling position of the second perforated rolling roll disposed on the upstream stand is also outward. Will change. In other words, even when rolling the blank tube at a stand located upstream of the finishing stand by two stands, the reduction position of the second perforated rolling roll disposed on the stand is changed outward. become. Therefore, since the amount of reduction at the bottom of the groove when rolling the raw tube with the second hole rolling roll is reduced, the portion of the portion facing the flange portion of the hole rolling roll disposed on the next stand is thereby reduced. The thickness is not excessively reduced, and as a result, “groove bottom unrolled” does not occur when rolling with the first perforated rolling roll disposed in the next finishing stand. Thereby, while being able to roll an element pipe to desired wall thickness accurately, the outstanding advantage that the surface property of an element pipe is not deteriorated is acquired.

FIG. 1 is a block diagram schematically showing a schematic configuration of a rolling control apparatus for carrying out the mandrel mill rolling control method according to the first embodiment of the present invention. FIG. 2 is a block diagram schematically showing a schematic configuration of a rolling control apparatus for carrying out the mandrel mill rolling control method according to the second embodiment of the present invention. FIG. 3 is a block diagram schematically showing a schematic configuration of a rolling control apparatus for carrying out the mandrel mill rolling control method according to the third embodiment of the present invention. FIG. 4 is a schematic diagram illustrating an example of a rolling position variation pattern of the perforated rolling roll disposed on the finishing stand.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings as appropriate. In addition, in the embodiment described below, when rolling the end portion of the raw tube in the finishing stand, an aspect in which the rolling position of the perforated rolling roll disposed in the finishing stand is changed outward will be described. The present invention is not limited to this, and includes the case where the rolling position of the perforated rolling roll disposed on the finishing stand is changed outward over the entire length of the raw tube.
<First Embodiment>
FIG. 1 is a block diagram schematically showing a schematic configuration of a rolling control apparatus for carrying out the mandrel mill rolling control method according to the first embodiment of the present invention.
As shown in FIG. 1, the rolling control device 1 according to the present embodiment includes a first reduction position adjustment device 11, a second reduction position adjustment device 12, and an arithmetic control device 13.

  The first reduction position adjusting device 11 is composed of a cylinder or the like for adjusting the reduction position of the perforated rolling roll disposed in the finishing stand #i among the stands constituting the mandrel mill M. The second reduction position adjusting device 12 is disposed in the nearest upstream stand (which becomes a stand located upstream of the finishing stand #i by two stands) # i-2, which has the same reduction direction as the finishing stand #i. It is comprised from the cylinder etc. for adjusting the rolling-down position of the perforated rolling roll made. The arithmetic control device 13 is connected to the first reduction position adjustment device 11 and the second reduction position adjustment device 12, and based on the current position of the end of the raw tube S, the first reduction position adjustment device 11 and the second reduction position adjustment device 11. The second reduction position adjusting device 12 is configured to instruct a predetermined reduction position adjustment amount. In addition, both the 1st and 2nd rolling-down position adjustment apparatuses 11 and 12 which concern on this embodiment are the position (a front-end | tip part, a center part, a rear end of the said raw pipe S during rolling of the single raw pipe S. Part) is a mechanism that can vary the rolling position of the perforated rolling roll.

  The arithmetic and control unit 13 is composed of a computer having hardware such as a CPU, a memory, an external storage device, an external input / output interface, and the like, and by appropriately driving these hardware according to a built-in control program, the first control unit 13 It functions as a reduction position setting unit 131 and a second reduction position setting unit 132.

  For example, an end detection signal indicating that the end of the raw tube S has been detected by a detection sensor (not shown) disposed on the entry side of the mandrel mill M is input to the first reduction position setting unit 131. Is done. Further, for example, the distance between the detection sensor and the stand #i, the transport speed of the raw tube S, the stretch rate of the raw tube S in the mandrel mill M, and the like are input from a host process computer (not shown). The first reduction position setting unit 131 calculates the current position of the end portion of the raw tube S based on the input signal and data. More specifically, the timing at which the end portions (the front end portion and the rear end portion) of the raw tube S reach the finishing stand #i and the exit timing are calculated.

  The first reduction position setting unit 131 sets the reduction position adjustment amount of the first perforated rolling roll disposed in the finishing stand #i based on the calculated timing, and the set reduction position adjustment amount. Is transmitted to the first reduction position adjusting device 11. More specifically, the first reduction position setting unit 131 includes a reduction position A of the first perforated rolling roll when the end of the raw pipe S is rolled in the finishing stand #i, and the raw pipe. The rolling position B of the first perforated rolling roll when rolling the central portion of S is stored. The first reduction position setting unit 131 is configured so that the first perforated rolling roll is changed from the reduction position B to the reduction position A by the timing when the tip of the raw tube S reaches the finishing stand # 1. B is set as the reduction position adjustment amount, and this is transmitted to the first reduction position adjustment device 11. Similarly, the first reduction position setting unit 131 is configured to change the first perforated rolling roll from the reduction position A to the reduction position B at the timing when the tip of the raw tube S comes out of the finishing stand # 1. B-A is set as the reduction position adjustment amount, and this is transmitted to the first reduction position adjustment device 11. Thereafter, at the timing when the rear end portion of the raw tube S reaches the finishing stand # 1, AB is set as the reduction position adjustment amount, and this is transmitted to the first reduction position adjustment device 11. Further, the first perforated rolling roll is rolled down from the timing when the rear end portion of the blank tube S comes out of the finishing stand # 1 to the timing when the leading end portion of the blank tube S to be rolled next reaches the finishing stand # 1. In order to change from the position A to the reduction position B, B-A is set as the reduction position adjustment amount, and this is transmitted to the first reduction position adjustment device 11.

  With the above configuration, when rolling the end portion of the raw tube S in the finishing stand #i, the reduction position of the first perforated rolling roll disposed on the finishing stand #i is outward (that is, the reduction position). B) can be varied. Note that the reduction positions A and B have different values depending on the dimensions, thickness, material, and the like of the raw tube S to be rolled. Therefore, the first reduction position adjusting device 11 has dimensions, thicknesses, materials, and the like. A plurality of reduction positions A and B according to the above are stored, and for example, it is configured so as to be appropriately selected according to the size, thickness, material, etc. of the raw tube S input from the host process computer.

  Similarly to the first reduction position setting unit 131, an end detection signal or the like is input from the outside to the second reduction position setting unit 132, and the ends (front end and rear end) of the raw tube S are upstream. The timing to reach stand # i-2 and the exit timing are calculated.

  Moreover, the 2nd rolling position setting part 131 is the 2nd roll-type rolling roll arrange | positioned by upstream stand # i-2 based on the calculated timing similarly to the 1st rolling position setting part 131. Is set, and the set reduction position adjustment amount is transmitted to the second reduction position adjustment device 12. It should be noted that the reduction position adjustment amount transmitted to the second reduction position adjusting device 12 (that is, when the end of the raw pipe S is rolled in the upstream stand # i-2, the upstream position # i-2 is assigned to the upstream stand # i-2. It is necessary to set the same value as the reduction position adjustment amount to be transmitted to the first reduction position adjustment device 1) (corresponding to the fluctuation amount for changing the reduction position of the second roll-type rolling roll provided outward). For example, it is possible to set a value obtained by multiplying a predetermined coefficient (for example, 0.8 or the like) larger than 0 and smaller than 1.

  According to the rolling control device 1 according to the present embodiment described above, not only the finishing stand #i but also the end of the raw tube S is rolled in the upstream stand # i-2. The reduction position of the second hole-type rolling roll thus made will be changed outward. Accordingly, the amount of reduction at the bottom of the groove when the raw tube S is rolled with the second hole rolling roll is reduced, so that the portion facing the flange portion of the hole rolling roll disposed in the next stand Is not excessively reduced, and as a result, there is no occurrence of groove bottom unrolling when rolling is performed with the first perforated rolling roll disposed in the next finishing stand #i. Thereby, while being able to roll the edge part of the raw pipe S to the desired thickness accurately, the outstanding advantage that the surface property of the raw pipe S is not deteriorated is acquired.

  In the present embodiment, not only the first reduction position adjustment device 11 but also the second reduction position adjustment device 12 is configured to be a mechanism that can change the reduction position during rolling of the single pipe S. Explained. However, some mandrel mills M do not have the above-described mechanism except for the finishing stand #i. For such mandrel mills, the reduction position varies depending on the position of the raw tube S. Instead, it is only necessary to adopt a configuration in which the rolling position of the perforated rolling roll of the upstream stand # i-2 is changed outward before rolling the raw tube S.

  In the case of adopting such a configuration, the second reduction position setting unit 132, for example, at the timing when the distal end detection signal of the raw tube S is input from the outside, the reduction position adjustment amount (a prestored outer position). The adjustment amount necessary for changing to the reduction position) is set, and the set reduction position adjustment amount is transmitted to the second reduction position adjustment device 12. The second reduction position adjusting device 12 changes the reduction position of the second perforated rolling roll outward based on the transmitted reduction position adjustment amount. The changed reduction position is maintained at the same value during the rolling of the raw tube S.

<Second Embodiment>
FIG. 2 is a block diagram schematically showing a schematic configuration of a rolling control apparatus for carrying out the mandrel mill rolling control method according to the second embodiment of the present invention.
As shown in FIG. 2, the rolling control device 2 according to the present embodiment includes a reduction position adjusting device 21 and an arithmetic control device 22.

  The reduction position adjusting device 21 is composed of a cylinder or the like for adjusting the reduction position of the perforated rolling roll disposed in the finishing stand #i among the stands constituting the mandrel mill M, and is a single blank. During rolling S, the rolling position of the perforated rolling roll can be changed in accordance with the position of the raw pipe S (front end, center, rear end).

  As in the first embodiment, the arithmetic and control unit 22 is composed of a computer having hardware such as a CPU, but the exit side of the finishing stand #i (in this embodiment, the exit side of the mandrel mill M) ) And a wall thickness gauge I for measuring the thickness of the raw tube S along the rolling direction of each stand (for example, if the mandrel mill M is a two-roll type, the thickness is four directions). This is different from the first embodiment. The arithmetic and control unit 22 functions as a reduction position setting unit 221 and an unrolled determination unit 222 by appropriately driving hardware according to a built-in control program, and adjusts the reduction position based on the output of the thickness gauge I. It is configured to instruct the device 21 to interrupt the reduction position adjustment. More specific description will be given below.

  As with the first reduction position setting unit 131 described in the first embodiment, the end position detection signal of the raw tube S is input to the reduction position setting unit 221, and the end portion (tip portion) of the raw tube S is input. And the timing at which the rear end) reaches the finishing stand #i and the timing to exit. In addition, the reduction position setting unit 221 stores the reduction positions of the perforated rolling rolls when rolling the end portion and the center portion of the raw tube S in the finishing stand #i, respectively, as in the first embodiment. ing. The reduction position setting unit 221 sets the reduction position adjustment amount of the hole rolling roll disposed in the finishing stand #i based on the calculated timing and the stored reduction position of the hole rolling roll. The set reduction position adjustment amount is transmitted to the reduction position adjustment device 21. As a result, when rolling the end portion of the raw tube S in the finishing stand #i, the rolling position of the perforated rolling roll disposed in the finishing stand #i is set outward by an amount corresponding to the rolling position adjustment amount. It is possible to vary.

  The output of the thickness gauge I (the actual thickness of the end portion of the raw tube S) is input to the unrolled determination unit 222. In addition, the target thickness of the end portion of the raw tube S is stored in the unrolled determination unit 222 in advance. The unrolled determination unit 222 compares the target wall thickness of the raw tube S with the actual wall thickness, and the actual wall thickness is smaller than the target wall thickness (the actual wall thickness measured in the reduction direction of the finishing stand #i). If at least one of the actual wall thickness is smaller than the target wall thickness), it is determined that “groove bottom unrolled” has occurred, and in other cases, it has been determined that it has not occurred. In addition, since the target thickness of the edge part of the raw pipe S is a value which changes with dimensions, thickness (target thickness of the center part), material, etc. of the raw pipe S to be rolled, the first reduction position adjustment The apparatus 11 stores a plurality of target thicknesses corresponding to dimensions, thicknesses (thicknesses at the center), materials, and the like. For example, the dimensions of the raw tube S input from a host process computer, It is configured so as to be appropriately selected depending on the thickness (thickness of the central portion), material, and the like.

  When the unrolling determining unit 222 determines that “groove bottom unrolled” has occurred, the rolling reduction position setting unit 221 instructs to interrupt the rolling position variation of the perforated rolling roll for the raw tube S to be rolled next time. To do. In other words, when rolling the end portion of the raw pipe S, the reduction position adjusting device 21 is instructed to maintain the same reduction position as when the central portion of the raw pipe S is rolled. That is, the rolling position adjustment amount when rolling the end portion of the raw tube S is set to 0, and this is transmitted to the rolling position adjustment device 21. On the other hand, when it is determined in the unrolled determination section 222 that “groove bottom unrolled” has not occurred, the previously stored end and center portions of the raw tube S are also used for the raw tube S to be rolled next time. A reduction position adjustment amount is set in accordance with the reduction position of the perforated rolling roll when rolling, and this is transmitted to the reduction position adjustment device 21.

  According to the rolling control apparatus 2 according to the present embodiment described above, since the fluctuation to the outside of the perforated rolling roll is interrupted for the raw tube S to be rolled next time, the reduction of the perforated rolling roll is interrupted. It can be expected that the amount does not decrease and “groove bottom unrolling” in the finishing stand #i can be prevented. Thereby, while being able to roll the edge part of the raw pipe S to the desired thickness accurately, the outstanding advantage that the surface property of the raw pipe S is not deteriorated is acquired.

  In the present embodiment, when the “groove bottom unrolled” has not occurred, the amount of outward fluctuation of the perforated rolling roll with respect to the next raw pipe S is the raw pipe S measured by the thickness gauge I. The configuration in which the value is set in advance regardless of the actual thickness of the end portion has been described. More specifically, when it is determined in the unrolled determination unit 222 that “groove bottom unrolled” has not occurred, the end of the raw tube S stored in advance for the raw tube S to be rolled next time In addition, a configuration has been described in which the reduction position adjustment amount is set in accordance with the reduction position of the perforated rolling roll when each of the center portions is rolled, and this is transmitted to the reduction position adjustment device 21.

  However, the present invention is not limited to this, and when the “groove bottom unrolled” does not occur, the amount of fluctuation to the outside of the perforated rolling roll with respect to the next blank S is measured by the wall thickness gauge I. It is also possible to adopt a configuration that changes according to the actual thickness of the end of the raw tube S measured by the above. More specifically, for example, when the actual wall thickness is greater than the target wall thickness, the reduction position of the perforated rolling roll when rolling the end of the blank S is increased by the difference. Update and remember. And about the raw material pipe S rolled next time, the rolling-down position at the time of rolling the center part of the raw material pipe S memorize | stored previously, and the rolling-down position at the time of rolling the end part of the said update memorized pipe S Accordingly, it is possible to adopt a configuration in which the reduction position adjustment amount is set and transmitted to the reduction position adjustment device 21. In such a configuration, when it is determined that "groove bottom unrolled" has occurred, the change of the set value according to the actual wall thickness measured by the wall thickness gauge I is interrupted, and the raw tube S to be rolled next time What is necessary is just to apply the setting value this time. Thereby, it is possible to solve the problem that the perforated rolling roll is fluctuated infinitely outward.

  Further, in the present embodiment, the unrolled determination unit 222 compares the target wall thickness of the raw pipe S with the actual wall thickness, and determines the presence or absence of occurrence of “groove bottom unrolled” according to the size. did. However, the method of determining whether or not “groove bottom unrolled” has occurred in the unrolled determination unit 222 is not limited to this. For example, the amount of variation in the reduction position of the perforated rolling roll and the raw tube measured by the wall thickness meter I A method of comparing the amount of change in the actual wall thickness along the fluctuation direction of the S-type rolling mill roll and determining that “groove bottom unrolled” has occurred if the amount of change is smaller than the fluctuation amount. It is also possible.

  In this case, the unrolling determination unit 222 is a reduction position adjustment amount set by the reduction position setting unit 221 (a variation amount that causes the reduction position of the perforated rolling roll to change outward when the end of the raw tube S is rolled). ), And the reference thickness adjustment amount referred to, and the actual thickness of the end portion and the central portion of the raw tube S input from the wall thickness meter I (the actual thickness along the fluctuation direction of the perforated rolling roll) If the change amount is smaller than the fluctuation amount, the change in the actual wall thickness calculated by (thickness) is compared (the difference between the actual wall thickness at the end and the actual wall thickness at the center). It will be judged that this has occurred. The change amount and the variation amount are not compared as they are, but the change amount is compared with a value obtained by multiplying the variation amount by a predetermined coefficient (for example, 0.5 or the like) larger than 0 and smaller than 1, and still If the amount of change is smaller, it may be determined that “groove bottom unrolled” has occurred.

  Furthermore, as another determination method of whether or not “groove bottom unrolled” occurs in the unrolled determination unit 222, for example, the rolling position after the variation of the hole-type rolling roll for the unrolled tube S and the previously rolled unrolled tube The difference with the reduction position after the fluctuation | variation of the 1st hole-rolling roll about S is calculated, and the result along the fluctuation | variation direction of the hole-rolling roll measured with the wall thickness gauge I about the raw | natural pipe | tube S rolled this time Calculate the difference between the wall thickness and the actual wall thickness along the fluctuation direction of the perforated rolling roll measured with the wall thickness meter I for the previously rolled raw tube, and the difference between the reduction position and the actual wall thickness If the difference in the actual wall thickness is smaller than the difference in the reduction position, it is possible to adopt a method in which it is determined that “groove bottom unrolled” has occurred.

  In this case, the unrolling determination unit 222 is after the fluctuation of the punched rolling roll stored in the reduction position setting unit 221 (including the case where it is updated and stored as described in paragraph 0061) for the previously rolled raw tube S. The rolling position (that is, the rolling position when rolling the end portion of the raw pipe S) is referred to and stored, and the raw pipe S rolled this time is stored (updated) in the rolling position setting unit 221. By referring to the rolling position after fluctuation of the perforated rolling roll that is stored (that is, stored) (that is, the rolling position when rolling the end portion of the raw tube S), by subtracting the former from the latter, The difference in the reduction position (difference in the reduction position between the current rolling and the previous rolling) is calculated. Moreover, the unrolling determination part 222 has memorize | stored the actual wall thickness (the actual wall thickness along the fluctuation | variation direction of a perforated rolling roll) of the edge input from the wall thickness meter I about the raw tube S rolled last time. By subtracting this from the actual wall thickness (the actual wall thickness along the fluctuation direction of the perforated rolling roll) input from the wall thickness gauge I for the raw tube S that was rolled this time, the difference in the actual wall thickness (Difference in actual wall thickness between current rolling and previous rolling) is calculated. The unrolling determination unit 222 compares the difference in the reduction position with the difference in the actual wall thickness, and determines that “groove bottom unrolled” has occurred if the difference in the actual wall thickness is smaller than the difference in the reduction position. Will do. In addition, the difference between the reduction position and the difference in the actual thickness is not compared as they are, but a predetermined coefficient (for example, 0.5 or the like) larger than 0 and smaller than 1 in the difference in the actual thickness and the difference in the reduction position. It may be configured to compare with the value obtained by multiplying the values and determine that “groove bottom unrolled” has occurred if the difference in the actual wall thickness is still smaller.

<Third Embodiment>
FIG. 3 is a block diagram schematically showing a schematic configuration of a rolling control apparatus for carrying out the mandrel mill rolling control method according to the third embodiment of the present invention.
As shown in FIG. 3, the rolling control device 3 according to this embodiment includes a first reduction position adjustment device 31, a second reduction position adjustment device 32, and an arithmetic control device 33.

  The first reduction position adjusting device 31 is composed of a cylinder or the like for adjusting the reduction position of the perforated rolling roll disposed in the finishing stand #i among the stands constituting the mandrel mill M. The second rolling-down position adjusting device 32 is disposed in the nearest upstream stand that is the same in the rolling-down direction as the finishing stand #i (which becomes a stand positioned upstream by 2 stands from the finishing stand #i) # i-2. It is comprised from the cylinder etc. for adjusting the rolling-down position of the perforated rolling roll made. The arithmetic and control unit 33 is connected to the first reduction position adjustment device 31 and the second reduction position adjustment device 32, and has a predetermined reduction with respect to the first reduction position adjustment device 31 and the second reduction position adjustment device 32. The position adjustment amount is instructed. In addition, both the 1st and 2nd reduction position adjustment apparatuses 31 and 32 which concern on this embodiment are the position (a front-end | tip part, a center part, a rear end) of the said raw pipe S during rolling of the single raw pipe S. Part) is a mechanism that can vary the rolling position of the perforated rolling roll.

  As in the first embodiment, the arithmetic and control unit 32 is composed of a computer having hardware such as a CPU, but the exit side of the finishing stand #i (in this embodiment, the exit side of the mandrel mill M) ) And a wall thickness gauge I for measuring the thickness of the raw tube S along the rolling direction of each stand (for example, if the mandrel mill M is a two-roll type, the thickness is four directions). This is different from the first embodiment. The arithmetic and control unit 32 functions as a first reduction position setting unit 331 and a second reduction position setting unit 332 by appropriately driving hardware according to a built-in control program, and outputs the thickness gauge I and Based on the current position of the end of the raw tube S, the first reduction position adjustment device 31 and the second reduction position adjustment device 32 can be instructed to specify a predetermined reduction position adjustment amount. More specific description will be given below.

  Similarly to the first reduction position setting unit 131 described in the first embodiment, an end detection signal of the raw tube S is input to the first reduction position setting unit 331, and the end of the raw tube S is input. The timing at which (the front end portion and the rear end portion) reach the finishing stand #i and the timing to exit are calculated. Further, in the first reduction position setting part 331, as in the first embodiment, the first hole rolling roll (when rolling the end part and the center part of the blank S in the finishing stand #i, respectively) The reduction positions of the first perforated rolling rolls disposed on the finishing stand #i are stored. Based on the calculated timing and the stored first roll-type roll reduction position, the first roll-down position setting unit 331 includes the first roll-type roll provided in the finishing stand #i. A reduction position adjustment amount is set, and the set reduction position adjustment amount is transmitted to the first reduction position adjustment device 31. Thereby, when rolling the end portion of the raw tube S in the finishing stand #i, the amount corresponding to the reduction position adjustment amount is the reduction position of the first perforated rolling roll disposed in the finishing stand #i. Can only be varied outward.

  Here, the output of the thickness gauge I is input to the first reduction position setting unit 331 according to the present embodiment. Further, the target thickness of the end portion of the raw tube S is stored in the first reduction position setting unit 331 in advance. The first reduction position setting unit 331 compares the target wall thickness with the actual wall thickness of the raw tube S, and the actual wall thickness is smaller than the target wall thickness (the actual measurement measured in the reduction direction of the finishing stand #i). If at least one of the actual wall thicknesses is smaller than the target wall thickness), it is determined that "groove bottom unrolled" has occurred. In addition, instead of the method of determining the presence / absence of “groove bottom unrolled” by comparing the target wall thickness with the actual wall thickness, the method described in the second embodiment described above (see paragraphs 0062 to 0065). Similarly, it is also possible to apply another method for determining whether or not “groove bottom unrolled” has occurred. If the first rolling position setting unit 331 determines that “groove bottom unrolled” has occurred, the second rolling position setting unit 332 refers to this result and, as will be described later, the raw tube S to be rolled next time. In the upstream stand # i-2, which is located in the immediate vicinity of the finishing stand #i and has the same reduction direction as the thickness measurement direction in which the actual thickness is smaller, the second reduction position The adjustment device 32 is configured to instruct a predetermined reduction position adjustment amount.

  In addition, the 1st reduction position setting part 331 is the actual thickness of the pipe | tube S end part which measured the fluctuation | variation amount to the outward of the 1st hole-type rolling roll with respect to the next pipe | tube S by the wall thickness meter I. It is also possible to configure to change according to the above. More specifically, for example, when the actual wall thickness is larger than the target wall thickness, the reduction of the first perforated rolling roll when rolling the end portion of the raw tube S by the difference. Update position inward and store. And about the raw material pipe S rolled next time, the rolling-down position at the time of rolling the center part of the raw material pipe S memorize | stored previously, and the rolling-down position at the time of rolling the end part of the said update memorized pipe S Accordingly, it is possible to adopt a configuration in which a reduction position adjustment amount is set and transmitted to the reduction position adjustment device 31.

  Similarly to the first reduction position setting unit 331, an end detection signal or the like is input from the outside to the second reduction position setting unit 332, and the ends (front end and rear end) of the raw tube S are upstream. The timing to reach stand # i-2 and the exit timing are calculated.

  The second rolling-down position setting unit 332 refers to the first rolling-down position setting unit 331, and when the first rolling-down position setting unit 331 determines that “groove bottom unrolled” has occurred, the calculation is performed as described above. Based on the timing, a reduction position adjustment amount of the second perforated rolling roll disposed in the upstream stand # i-2 is set, and the set reduction position adjustment amount is set to the second reduction position adjustment device 12. To send. It should be noted that the reduction position adjustment amount transmitted to the second reduction position adjusting device 12 (that is, when the end of the raw pipe S is rolled in the upstream stand # i-2, the upstream position # i-2 is assigned to the upstream stand # i-2. For example, the first reduction position adjusting device 12 can calculate the amount of change of the second reduction roll provided by the first reduction position adjusting device 12. It is conceivable to obtain a value obtained by multiplying the difference between the target wall thickness and the actual wall thickness by a coefficient of about 0.8 to 1.2. Alternatively, a constant value (for example, 0.2 mm) may be considered until the difference between the target wall thickness and the actual wall thickness is equal to or less than a predetermined value (for example, 0.1 mm).

  According to the rolling control device 3 according to the present embodiment described above, when it is determined that “groove bottom unrolled” has occurred due to the output of the wall thickness gauge I, the finishing tube S to be rolled next time is finished. Not only the stand #i but also the second roll-type rolling roll placed on the upstream stand # i-2 having the same rolling direction as the direction in which it is determined that “groove bottom unrolled” has occurred. The position will be changed outward. Accordingly, the amount of reduction in the upstream stand # i-2 is reduced, and the thickness of the raw tube in the reduction direction is increased. Therefore, it is possible to prevent “groove bottom unrolling” when rolling in the finishing stand #i. Is possible. Thereby, while being able to roll the edge part of the raw pipe S to the desired thickness accurately, the outstanding advantage that the surface property of the raw pipe S is not deteriorated is acquired.

  In the present embodiment, not only the first reduction position adjustment device 31 but also the second reduction position adjustment device 32 is configured to be a mechanism that can change the reduction position during rolling of the single pipe S. Explained. However, some mandrel mills M do not have the above-described mechanism except for the finishing stand #i. For such mandrel mills, the reduction position varies depending on the position of the raw tube S. Instead, the configuration may be adopted in which the rolling position of the second perforated rolling roll of the upstream stand # i-2 is changed outward in advance before rolling the raw tube S.

Hereinafter, the features of the present invention will be further clarified by showing examples and comparative examples.
The rolling control method according to the present invention was applied to a 6-roll 2-roll mandrel mill (finishing stands were # 5 and # 6 stands), and a rolling test was performed under the following conditions.
(1) Element dimensions on the mill entry side: outer diameter 190mm, wall thickness 16mm, length 4600mm
(2) Mill tube side dimensions: outer diameter 168mm, wall thickness 5mm, length 15000mm
(3) Mandrel bar outer diameter: 158mm
(4) Target wall thickness (groove bottom wall thickness) on the exit side of each stand
# 1 stand: 10mm # 2 stand: 9mm # 3 stand: 6mm
# 4 stand: 5.5mm # 5 stand: 5mm # 6 stand: 5mm

<Example 1-1>
For the # 5 and # 6 stands, the rolling position of the perforated rolling roll was varied outward in the pattern shown in FIG. The # 3 and # 4 stands were also rolled in the same pattern with the rolling position of the perforated rolling roll varied outward. The # 1 and # 2 stands were rolled as initially set.

<Example 1-2>
The # 5 and # 6 stands were rolled in the same manner as in Example 1-1. However, the # 3 and # 4 stands were rolled with the variation amount of the pattern shown in FIG. 4 being 0.8 times (that is, a maximum of 0.4 mm). The # 1 and # 2 stands were rolled as initially set.

<Example 1-3>
The # 5 and # 6 stands were rolled in the same manner as in Example 1-1. However, for the # 3 and # 4 stands, the rolling position of the perforated rolling roll is set so that the target thicknesses are 6.5 mm (# 3 stand) and 6 mm (# 4 stand), respectively, before rolling the blank tube. Was rolled out after changing each to the outside. The # 1 and # 2 stands were rolled as initially set.

<Comparative Example 1>
For only the # 5 and # 6 stands, the rolling position of the perforated rolling roll was varied outward in the pattern shown in FIG. The # 1 to # 4 stands were rolled as initially set.

<Evaluation>
About Examples 1-1 to 1-3 and Comparative Example 1, the thickness defect rate of the blank after rolling was evaluated. Here, the difference between the measured thickness and the target thickness value (for example, in the case of Example 1, the end thickness target value is 5.5 mm) at the end of the rolled raw tube is the wall thickness. If there was a measurement location exceeding the range of ± 2% with respect to the target thickness value, the thickness was judged as defective. The thickness defect rate was defined by the following formula.
Thickness defect rate = number of defective wall thickness / total number of rolled (%)

表１に示すように、比較例１と異なり、実施例１−１〜１−３の全てについて素管の端部を所望する肉厚に精度良く圧延できることが分かった。 The evaluation results are shown in Table 1.

As shown in Table 1, unlike Comparative Example 1, it was found that the end portions of the raw pipes could be rolled with high accuracy to the desired thickness for all of Examples 1-1 to 1-3.

<Example 2-1>
For the # 5 and # 6 stands, the pattern shown in FIG. 4 is changed based on the actual wall thickness measured by the wall thickness meter when rolling the end of the raw tube to be rolled next time, and the changed pattern Then, the rolling position of the perforated rolling roll was varied outward. In other words, the set value (the reduction position fluctuation amount) is changed by an amount corresponding to the difference between the actual wall thickness and the target wall thickness so that the actual wall thickness approaches the target wall thickness. However, if the actual wall thickness is smaller than the target wall thickness, it is judged that "groove bottom unrolled" has occurred, and the change of the set value (pattern change) according to the actual wall thickness is interrupted. And it decided to roll with the set value of this time also about the blank pipe rolled next time. The # 1 to # 4 stands were rolled as initially set.

<Example 2-2>
The # 5 and # 6 stands were rolled in the same manner as in Example 2-1. However, as a method of determining whether or not “groove bottom unrolled” has occurred, the amount of variation in the rolling position of the perforated rolling roll and the actual meat along the direction of variation of the core perforated rolling roll measured with a wall thickness meter. A method of comparing with the amount of change in thickness and determining that “groove bottom unrolled” has occurred if the amount of change is 0.5 times or less of the amount of change is employed.

<Example 2-3>
For the # 5 and # 6 stands, the pattern shown in FIG. 4 is changed based on the actual wall thickness measured by the wall thickness meter when rolling the end of the raw tube to be rolled next time, and the changed pattern Then, the rolling position of the perforated rolling roll was varied outward. The # 3 and # 4 stands were also rolled in the same pattern as the # 5 and # 6 stands with the rolling position of the perforated rolling roll varied outward. The # 1 and # 2 stands were rolled as initially set.

<Example 2-4>
The # 5 and # 6 stands were rolled in the same manner as in Example 2-3. However, the # 3 and # 4 stands were rolled by increasing the pattern variation of the # 5 and # 6 stands by 0.8 times. The # 1 and # 2 stands were rolled as initially set.

<Example 2-5>
The # 5 and # 6 stands were rolled in the same manner as in Example 2-3. However, for the # 3 and # 4 stands, the rolling position of the perforated rolling roll is set so that the target thicknesses are 6.5 mm (# 3 stand) and 6 mm (# 4 stand), respectively, before rolling the blank tube. Was rolled out after changing each to the outside. The # 1 and # 2 stands were rolled as initially set.

<Example 2-6>
The # 5 and # 6 stands were rolled in the same manner as in Example 2-3. If the actual wall thickness is smaller than the target wall thickness, it is determined that “groove bottom unrolled” has occurred, and the actual wall thickness is located in the immediate vicinity of the finishing stand (# 5, # 6 stand). The upstream stand (at least one of the # 3 and # 4 stands) having the same reduction direction as the thickness measurement direction in which the smaller thickness is obtained is the same pattern as the # 5 and # 6 stands. Rolling was performed with the rolling position of the perforated rolling roll varied outward. The # 1 and # 2 stands (and the # 3 and # 4 stands, which were not changed) were rolled as originally set.

<Example 2-7>
Rolled in the same manner as in Example 2-6. However, as a method of determining whether or not “groove bottom unrolled” has occurred, the amount of variation in the rolling position of the perforated rolling roll and the actual meat along the direction of variation of the core perforated rolling roll measured with a wall thickness meter. A method of judging that “groove bottom unrolled” has occurred when the amount of change is compared with the amount of change of thickness and is less than 0.5 times the amount of change.

<Comparative Example 2>
Only for the # 5 and # 6 stands, the pattern shown in FIG. 4 was changed on the basis of the actual thickness measured by the thickness meter when rolling the end of the raw tube to be rolled next time, and the changed pattern Then, the rolling position of the perforated rolling roll was varied outward. The # 1 to # 4 stands were rolled as initially set.

<Evaluation>
About Examples 2-1 to 2-7 and Comparative Example 2, the thickness defect rate of the blank after rolling was evaluated. Since the definition of the thickness defect rate is the same as that described above, the description thereof is omitted. Further, the frequency at which the rolling position of the perforated rolling rolls arranged on the finishing stands # 5 and # 6 was changed outward by 1 mm or more from the initial set value was also evaluated. The latter is an evaluation equivalent to the frequency with which the perforated rolling rolls of the finishing stand are moved indefinitely in the event that "groove bottom unrolled" occurs and the actual wall thickness becomes smaller than the target wall thickness. It is an indicator.

表２に示すように、実施例２−１〜２−７については、比較例２に比べて素管の端部を所望する肉厚に精度良く圧延できることが分かった。また、比較例２と異なり、仕上スタンドの孔型圧延ロールを外方に際限なく変動させてしまう事態は生じなかった。 The evaluation results are shown in Table 2.

As shown in Table 2, it was found that in Examples 2-1 to 2-7, the end portion of the raw tube could be rolled to a desired thickness with higher accuracy than in Comparative Example 2. Further, unlike Comparative Example 2, there was no situation where the perforated rolling roll of the finishing stand was endlessly varied outward.

DESCRIPTION OF SYMBOLS 1 ... Rolling control apparatus 11 ... 1st reduction position adjustment apparatus 12 ... 2nd reduction position adjustment apparatus 13 ... Arithmetic control apparatus M ... Mandrel mill S ... Elementary pipe 131- ..First reduction position setting unit 132 ... Second reduction position setting unit

Claims (4)

Rolling control of a mandrel mill that varies the reduction position of the first perforated rolling roll disposed in the finishing stand when rolling the blank tube in the finishing stand among the stands constituting the mandrel mill. A method,
When rolling the raw pipe in the nearest upstream stand whose rolling direction is the same as that of the finishing stand, the rolling position of the second hole rolling roll disposed on the upstream stand is also the first hole rolling roll. The mandrel mill rolling control method is characterized by varying outward as in the above. Of each stand constituting the mandrel mill, a first reduction position adjusting device for adjusting the reduction position of the perforated rolling roll disposed in the finishing stand, and the latest reduction stand having the same reduction direction as the finishing stand A second rolling position adjusting device for adjusting the rolling position of the rolling mill roll disposed in the upstream stand, and a hole type with respect to the first rolling position adjusting device and the second rolling position adjusting device. A rolling control device comprising a calculation control device for instructing the rolling position adjustment amount of the rolling roll,
The arithmetic control device instructs a predetermined reduction position adjustment amount to the first reduction position adjustment device and the second reduction position adjustment device based on a current position of the raw pipe. A rolling control device for a mandrel mill, characterized in that the rolling control method described in 1 is implemented. Of each stand constituting the mandrel mill, a first reduction position adjusting device for adjusting the reduction position of the perforated rolling roll disposed in the finishing stand, and the latest reduction stand having the same reduction direction as the finishing stand Connected to a second reduction position adjusting device for adjusting the reduction position of the perforated rolling roll disposed in the upstream stand, and with respect to the first reduction position adjustment device and the second reduction position adjustment device A control program for operating an arithmetic and control unit that instructs a rolling position adjustment amount of the hole rolling roll,
The rolling control method according to claim 1, wherein a predetermined reduction position adjustment amount is instructed to the first reduction position adjustment device and the second reduction position adjustment device based on a current position of the raw pipe. A control program for operating the arithmetic and control unit to implement   A seamless pipe manufactured using a mandrel mill which has performed the rolling control method according to claim 1.

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