US3512403A - Method of determining the pierceability of seamless metal tubes - Google Patents

Method of determining the pierceability of seamless metal tubes Download PDF

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Publication number
US3512403A
US3512403A US717474A US3512403DA US3512403A US 3512403 A US3512403 A US 3512403A US 717474 A US717474 A US 717474A US 3512403D A US3512403D A US 3512403DA US 3512403 A US3512403 A US 3512403A
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US
United States
Prior art keywords
piercing
plug
rolls
billet
delivery
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
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US717474A
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English (en)
Inventor
Kenzo Kato
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
JFE Engineering Corp
Original Assignee
Nippon Kokan Ltd
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Filing date
Publication date
Application filed by Nippon Kokan Ltd filed Critical Nippon Kokan Ltd
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B19/00—Tube-rolling by rollers arranged outside the work and having their axes not perpendicular to the axis of the work
    • B21B19/02—Tube-rolling by rollers arranged outside the work and having their axes not perpendicular to the axis of the work the axes of the rollers being arranged essentially diagonally to the axis of the work, e.g. "cross" tube-rolling ; Diescher mills, Stiefel disc piercers or Stiefel rotary piercers
    • B21B19/04—Rolling basic material of solid, i.e. non-hollow, structure; Piercing, e.g. rotary piercing mills
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
    • G01M99/00—Subject matter not provided for in other groups of this subclass

Definitions

  • a billet is pierced by a Mannesmann type piercer without utilizing a piercing plug, and the angle of delivery of the work rolls is varied such that the delivery speed of the billet in the absence of the piercing plug becomes equal to that of the billet in the presence of the piercing plug.
  • the operating conditions are then varied until the produced tube has the desired characteristics.
  • This invention relates to a method of determining the optimum working conditions required for producing high grade seamless metal tubes halving excellent internal surfaces.
  • the method utilizing the hot twist testing machines contemplates to stimulate the twisting action of the Mannesmann piercer by varying the working speed, working temperature, rate of reduction, and so forth, to determine the correct conditions for the piercing operation.
  • this method although it is possible to perform twist working for the surface layer of the peripheral zone of the test piece, the actual piercing operation is performed by the piercing plug at the center of the test piece.
  • a Mannesmann type piercer wherein a -pair of working rolls is employed each comprising two oppositely inclining conical surfaces and the test piece is fed into a gap between these working rolls to form a center hole by the rotating forging effect afforded thereby without utilizing the piercing plug.
  • the delivery angle of said work rolls with respect to the pass line of the material is varied to determine the minimum rate of reduction at a piercing point, and the piercing workability of the test piece is determined in accordance with the minimum rate of reduction.
  • the delivery angle of the working rolls is selected to provide the same spiral feed speed of the material in the absence of the piercing plug as that of the material when the piercing plug is utilized.
  • FIG. 1 shows a front view of the piercing rolls
  • FIG. 2 is a plan view of the rolls shown in FIG. 1;
  • FIG. 3 is a schematic side view, partly in section, showing the conventional method of manufacturing a seamless metal tube by utilizing a piercing plug;
  • FIG. 4 is a schematic side view showing the method of manufacturing a seamless metal tube without utilizing the piercing plug.
  • FIG. 5 is a longitudinal sectional view of a tapered billet subjected to the rotating forging effect provided by the working method shown in FIG. 4.
  • the method of manufacturing a seamless steel tube by means of the Mannesmann piercer will be outlined here under.
  • the piercing rolls utilized in this type of piercer comprise two symmetrical conical work rolls each having two oppositely inclined conical faces inclined at an angle a. Each roll is inclined at a delivery angle 6 with respect to the pass line of the material (hereafter designated as the roll delivery angle).
  • material 4 will rotate and advance with the peripheral velocity of the work rolls to reduce its cross-section until the maximum roll diameter portion or the gouge portion is reached.
  • the rotating forging effect afforded by the rolls loosens the structure of the core portion of the material so that a piercing plug 3 set near the gouge portion enlarges the central hole and reduces the thickness of the tube wall, thereby producing -a seamless tube.
  • said rotating forging effect plays a most important role.
  • the piercing or working rolls 1 and 2 constantly apply pressure to the material 4 from its periphery, and the magnitude of this pressure has a large influence upon the internal finish of the resulting seamless metal tube. The rate of reduction is also dependent upon the characteristics of the material, working temperature and other parameters.
  • the tube When the piercing plug is not used the tube is manufactured at an entry speed v and an exit speed v as shown in FIG. 4.
  • the resistance due to the piercing plug 3 reduces the entry speed so that v V
  • the delivery speeds in the two cases is much different.
  • the reduction is gradually applied whereas in the other case the reduction is rapidly increased, thus resulting in a large difference in the rotating forging effect imparted to the material 4. Therefore, the prior art testing methods are not capable of providing accurate enough results.
  • the delivery angle of piercing rolls 1 and 2 with respect to the pass line of the material being worked is changed so that the rotating forward motion of the material 4 at the entry side of rolls 1 and 2 in the case where the piercing 3 is not utilized is made equal to that of the material in the actual case (i.e., under actual operating conditions) where the piercing plug 3 is utilized.
  • Dia. of work rolls-D 915 mm.
  • a particular value of the roll delivery angle 6 is selected in order to obtain the same feed speed without utilizing the piercing plug as the spiral feed speed of the material in the actual piercing operation.
  • the test piece is feed between piercing rolls (which are rotating in the same direction) to subject it to the rotating forging action.
  • piercing rolls which are rotating in the same direction
  • the roll delivery angle is reset to provide the same feed speed with the piercing plug, the piercing plug is placed in position and the actual piercing operation can be carried out.
  • a tapered billet was used in this example as the test piece.
  • the billet was inserted in the piercing roll gap of 25 mm. with the smaller diameter portion inserted first.
  • the billet is subjected to the rotating foregoing action without utilizing the piercing plug.
  • FIG. 5 which shows a longitudinal section of the billet, the rate of reduction is 0% at one end of the blank 11 (corresponding to the end of the tapered billet havingthe diameter of 25 mm.) whereas that of the other end is 20%. At portions intermediate these ends the rate of reduction varies from 0 to 20%.
  • the numeral 12 denoting the point at which the rupture begins to form corresponds in this example to the point of 10% reduction. It was found that, in order to provide a satisfactory internal surface, the rate of reduction should be lower than the rate of reduction at the point 12 at which the rupture begins to occur (hereinafter designated as the critical rate of reduction). Thus, it becomes possible to determine the optimum piercing conditions from this critical rate of reduction. Accordingly, it can be readily noted that a desired rate of reduction for the billet is less than 10% As has been pointed out hereinabove, by the prior method of hot twist testing, it has been impossible to properly check the rotating rolling effect at the entry side of the piercing rolls.
  • the roll delivery angle is varied to provide the same delivery speed of the billet in the absence of the piercing plug as that of the actual piercing operation utilizing the piercing plug.
  • This invention makes it possible to determine whether the central hole which is formed by the actual rotating forging effect at the entry section of the piercing rolls is acceptable or not. Consequently, it is now possible, by means of the present invention, to readily determine the optimum rate of reduction of various steel stocks at their actual working temperatures. When the actual piercing operation is carried out under the optimum operating conditions obtained in accordance with the present invention, it is possible to produce seamless metal tubes having excellent internal surface properties.
  • step of varying the operating conditions includes varying the position of said piercing rolls to a point at which metal rupture occurs in the center of said billet, thereby arriving at the minimum rate of reduction.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Forging (AREA)
  • Control Of Metal Rolling (AREA)
US717474A 1967-03-30 1968-03-29 Method of determining the pierceability of seamless metal tubes Expired - Lifetime US3512403A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP1950067 1967-03-30

Publications (1)

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US3512403A true US3512403A (en) 1970-05-19

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US717474A Expired - Lifetime US3512403A (en) 1967-03-30 1968-03-29 Method of determining the pierceability of seamless metal tubes

Country Status (5)

Country Link
US (1) US3512403A (cs)
CS (1) CS165328B2 (cs)
DE (1) DE1773105A1 (cs)
FR (1) FR1578852A (cs)
GB (1) GB1208203A (cs)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3719066A (en) * 1969-11-05 1973-03-06 Sumitomo Metal Ind Piercing rolling apparatus for producing rolled material free from surface torsion
US20090312110A1 (en) * 2006-07-07 2009-12-17 Gesenkschmiede Schneider Gmbh Method for the production of a rotationally symmetrical part, and part produced according to said method

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US389585A (en) * 1888-09-18 Seamless tubes

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US389585A (en) * 1888-09-18 Seamless tubes

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3719066A (en) * 1969-11-05 1973-03-06 Sumitomo Metal Ind Piercing rolling apparatus for producing rolled material free from surface torsion
US20090312110A1 (en) * 2006-07-07 2009-12-17 Gesenkschmiede Schneider Gmbh Method for the production of a rotationally symmetrical part, and part produced according to said method
US8312750B2 (en) * 2006-07-07 2012-11-20 Gesenkschmiede Schneider Gmbh Method for the production of a rotationally symmetrical part, and part produced according to said method

Also Published As

Publication number Publication date
DE1773105A1 (de) 1971-09-23
FR1578852A (cs) 1969-08-22
GB1208203A (en) 1970-10-07
CS165328B2 (cs) 1975-12-22

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