Technology for Manufacturing Hollow Products of Solid Blanks by Radial Forging without Piercing
- Author: Viktor Lazorkin, Ph.D.
Company: TECHNONOVA Co., Ltd.
Contact info: - Novitskogo, 10, k.2
- 69035, Zaporozhye, UKRAINE
Web site: www.technonova.nm.ru
e-mail: technonova@nm.ru
The technology is based on special modes of deformation
of solid blanks in radial forging machine (RFM). No preliminary heat of
blanks and no use of a piercer are needed. The latter can be optionally
applied as a calibrating tool, but not as a forming instrument.
Essence
of the technology
Long blank of round or polyhedral cross-section, which
can be preliminary heated, is gripped by a manipulator intended to rotate
it slowly and feed it in axial direction into the forming unit where the
blank is reduced on perimeter by radial positioned dies.
Modes of reducing, feeding and canting are selected so
that tensile stresses acting in core zone of the blank exceed ultimate
stress limit of the blank material. Frequently changing deformations under
tensile stress lead to opening of an axial hollow in the blank of
practically any material including high-plastic ones. Opening and
development of the axial hollow result in formation and growth of an axial
hole of regular shape in the blank while continuousness of the rest of the
blank is kept intact.
Capabilities
of the technology
The technology is capable of:
-
Manufacture of forged hollow shafts (e. g. motor shafts) of solid blanks. It is well known that core zone of a shaft does not work for torque transfer and solid shafts can be replaced with hollow ones without any loss of strength while saving metal.
-
-
Manufacture of forged tubes (from 15 mm in diameter) including those with big diameters (up to 1000-1300 mm) and wall thickness of 25 to 100 mm and higher.
-
Manufacture of forged tubes for underwater drilling equipment, special hollow extenders for various purposes, piercer plugs for tube mills, etc.
No high forces of forging are needed. For example,
conventional radial forging machine of 1000 tons is capable of forging
blanks with maximum diameter of 550 mm. The technology considered makes it
possible to forge solid blanks of 1000-1200 mm into tubes of 900-1200 mm
in the RFM mentioned above. There are more powerful RFMs (1600, 2500, 4000
tons, etc.) capable of manufacturing hollow forged products with diameter
of 1500-3000 mm.
The technology can be successfully applied for
manufacture of high-quality thick-walled tubes (with diameter of 1000-1300
mm and wall thickness of 25-50 mm and more) working under pressures
exceeding 15 MPa. Such tubes can be used for construction of deep-sea oil
and gas pipelines.
The technology enables manufacturing of forged pipes
with big diameters of steels with practically any chemical composition
instead of welded ones. The technology essentially increases reliability
of pipelines, their pipe capacity for account of higher working pressures
allowable and makes it possible to manufacture tubes with almost any
thickness of walls.
Prospects
of the technology
If further developed, the technology can be used for:
-
manufacture of parts with internal cavities;
-
At first, the blank is forged to obtain a closed
cavity. Then, the cavity is closed by all-round deformation. For all that,
forging force needed is 2-4 times less.
Economic
efficiency
Economic efficiency of the technology is obvious:
-
metal savings of 30 to 50 % in comparison with the technology using the drilling;
-
-
lower forging force needed by 2-4 times;
-
manufacture of long parts including those with big cross-sections of practically any steels and alloys;
-
manufacture of tubes of any length limited only by the length of the blank.
Implementation
of the technology
The technology has been implemented for the
industrial-scale radial forging machine of 160 tons to manufacture hollow
products with outer diameter of 40 to 200 mm of structural alloyed and
tool steels, aluminum and aluminum alloys, high-temperature alloys.
Patents
for the technology
The technology has been protected with the following
patents:
-
Russia, No. 2000160C, No. 2083310
-
USA, No. 5572897
-
Europatent, No. 0610509.
Information supplied by the Author May 2001. Page last updated: January 19, 2004
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