Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21C—MANUFACTURE OF METAL SHEETS, WIRE, RODS, TUBES OR PROFILES, OTHERWISE THAN BY ROLLING; AUXILIARY OPERATIONS USED IN CONNECTION WITH METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL
  • B21C23/00—Extruding metal; Impact extrusion
  • B21C23/02—Making uncoated products
  • B21C23/04—Making uncoated products by direct extrusion
  • B21C23/08—Making wire, bars, tubes
  • B21C23/085—Making tubes
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10S29/00—Metal working
  • Y10S29/047—Extruding with other step
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T29/00—Metal working
  • Y10T29/49—Method of mechanical manufacture
  • Y10T29/4998—Combined manufacture including applying or shaping of fluent material
  • Y10T29/49988—Metal casting
  • Y10T29/49989—Followed by cutting or removing material

Definitions

• seamless steel tubing was generally produced by breaking down an ingot through hot working into a bloom and then in subsequent operations reducing the bloom ultimately into a round billet which was then directed through various piercing mills, plug rolling mills, reeling machines and sizing machines. Depending on the size of the end product some operations were repeated, e.g., two piercing mills, and there were many intermediate heating operations as well as other operations such as rotary. rolling mills which were employed.
• One solution included cutting the cast bar into billets, heating the billets and then forming round blanks which are made hollow by hot piercing, elongating the blanks on known equipment to reduce mainly the outside diameter and to a lesser extent the wall thickness, cutting the hollow product in several parts which are rolled on mandrel mills to reduce mainly wall thickness and to a lesser extent the outside diameter, and then sizing the outside diameter on a stretch reducing mill.
• Various push benches, rolling mills and extrusion presses were employed to obtain the product for the mandrel mills.v
• Our invention avoids all the drawbacks of the previously tried processes for producing seamless tubing and results in a high quality product manufactured with a minimum of processing steps and with a maximum yield of metal from the cast bar to the finish product. Therefore, not only is a cost savings realized by the use of the continuous cast bar, but the cost savings is substantially increased by the high metal yield, good quality product and the elimination of the many processing steps employed heretofore.
• our process includes continuous casting a bar, cutting the bar into billets, heating the billets, upsetting and piercing the billets into hollow circular blanks, hot extruding the blanks into tubes and reducing the diameter of the tubes on a stretch reducing mill where necessary.
• Our invention permits the utilization of all steels which can be continuously cast for manufacture into seamless steel tubes having diameters greater than .8 inches and wall thicknesses above .120 inches. It is understood' that continuous casting produces bars of square or rectangular cross-section and as used herein, rectangular cross-section is employed to cover both cross-sections.
• the steel is continuous cast into rectangular bars which are cut into billets. This cutting can be done by flame cutting on the casting machine with the length corresponding to the weight to be extruded.
• the billets are then heated to a temperature of about l830 to 2280 F as is appropriate for the particular steel type and then descaled.
• the billets can be immediately reheated from the casting step, thereby retaining the casting heat and minimizing the amount of additional heat input from the reheating operation.
• the reheated billets are then inserted into a round container of a piercing press where they are first upset and then pierced and severed from the piercing discard.
• the upsetting-piercing operations are advantageously carried out with the aid of a glass-like lubricant.
• the resultant blank is cylindrical, thatis, circular in cross-section and hollow.
• the blanks can then be sent to the extrusion press without intermediate heating, provided the extrusion press is of sufficient power to handle them.
• the larger the blanks the slower the cooling rate, and this, along with efficient handling techniques and proper positioning of equipment, further aids in eliminating any intermediate heating.
• the blanks are hot extruded into seamless tubes of relatively large diameter.
• the product from the extrusion press is sent into a stretch reducing mill to reduce the diameter and adjust the wall thickness to the precise desired size.
• the temperature of the tube running into the stretch reducing mill may be maintained and kept as a constant value by employing an in line furnace at the exit end of the extrusion press.
• Our process therefore, takes advantage of the upsetting, piercing and extrusion operation to admit as starting material a rectangular billet with an internal cast structure. It can be seen this process is conducted with a single reheat step and since there is a minim um of processing steps, the cast bar to seamless tube metal yield is high. In addition, the metallurgical properties are excellent and the surface condition is improved because of the elimination of handling and various mechanical processing steps.
• the modern industrial extrusion press is capable of handling heavy blanks and the hourly output compares advantageously with the various large tubing mills, as well as welded tubing in stallations.
• the hourly output from the upsetting piercing press and the extrusion press may be high enough and tube sizing critical enough that it may be advisable to operate two stretch reducing mills in parallel downstream of the extrusion press.

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Forging (AREA)
• Extrusion Of Metal (AREA)
• Metal Extraction Processes (AREA)
• Heat Treatment Of Steel (AREA)
• Continuous Casting (AREA)

Applications Claiming Priority (1)

Publications (1)

Family

ID=9040588

Family Applications (1)

Country Status (12)

Cited By (7)

Families Citing this family (1)

Citations (7)

• 1969
  • 1969-09-25 FR FR6932680A patent/FR2058777A5/fr not_active Expired
• 1970
  • 1970-09-09 ZA ZA706157A patent/ZA706157B/xx unknown
  • 1970-09-10 DE DE19702044815 patent/DE2044815B2/de active Pending
  • 1970-09-10 SE SE7012343A patent/SE380189B/xx unknown
  • 1970-09-22 AU AU20213/70A patent/AU2021370A/en not_active Expired
  • 1970-09-23 LU LU61742D patent/LU61742A1/xx unknown
  • 1970-09-23 ES ES383918A patent/ES383918A1/es not_active Expired
  • 1970-09-24 GB GB4565670A patent/GB1318607A/en not_active Expired
  • 1970-09-24 CA CA094027A patent/CA932293A/en not_active Expired
  • 1970-09-24 US US75273A patent/US3698070A/en not_active Expired - Lifetime
  • 1970-09-25 RO RO64532A patent/RO56792A/ro unknown
  • 1970-09-25 AT AT867170A patent/AT308498B/de not_active IP Right Cessation

Patent Citations (7)

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