Rotary piercing

Rotary piercing

Rotary piercing is a hot working metalworking process for forming thick-walled seamless tubing. There are two types: the Mannesmann process and Stiefel process.

Mannesmann process

A schematic of rotary piercing. Key:
1. Roller configuration
2. The process starts with the blank fed in from the left.
3. The stresses induced by the rolls causes the center of the blank to fracture.
4. Finally, the rolls push the blank over the mandrel to form a uniform inner diameter.

A heated cylindrical billet is fed between two convex-tapered rollers, which are rotating in the same direction. The rollers are usually 6° askew from parallel with the billet's longitudinal axis. The rollers are on opposite sides of the billet and the surface of their largest cross sections are separated by a distance slightly smaller than the outer diameter (OD) of the original billet. The load imparted by the rollers compresses the material and the 6° skew provides both rotation and translation to the billet. The friction from between the rollers and the billet is intentionally high and many times increased with knurling of the rollers. This friction sets up stresses varying radially through the billet cross section with the highest stresses are at the OD and the central axis. The stress exceeds the yield strength of the billet and cause circumferential fissures to propagate at various radii near the OD and a central longitudinal void to form at the axis. A tapered mandrel is set inside and a short distance from the start of the central void. This mandrel forces the material outward and compresses the material against the back side of the tapered rollers. This compressive loading fuses the various circumferential fissures and sets the initial internal diameter and OD values. The newly formed tube is then cooled and can be cold worked to further refine the diameters and to gain the desired yield strengths.[1]

Mannesmann mills can produce tubes as large as 300 mm (12 in) in diameter.[1]

Stiefel process

The Stiefel process is very similar to the Mannesmann process, except that the convex rollers are replaced with large conical disks. This allows for larger tubes to be formed.[1]

References

  1. ^ a b c Degarmo, E. Paul; Black, J T.; Kohser, Ronald A. (2003), Materials and Processes in Manufacturing (9th ed.), Wiley, p. 404, ISBN 0-471-65653-4. 

Wikimedia Foundation. 2010.

Игры ⚽ Нужен реферат?

Look at other dictionaries:

  • Tubing (material) — Tubing is a pipe or hollow cylinder for the conveyance of fluids (liquids or gases). The terms pipe and tubing are almost interchangeable, although minor distinctions exist (generally, tubing implies tighter engineering requirements than pipe ).… …   Wikipedia

  • Hot working — In materials science, hot working refers to processes where metals are deformed above their recrystallization temperature. Such temperatures are usually well above room temperatures (lead is an exception due to its low melting point). This… …   Wikipedia

  • steel — steellike, adj. /steel/, n. 1. any of various modified forms of iron, artificially produced, having a carbon content less than that of pig iron and more than that of wrought iron, and having qualities of hardness, elasticity, and strength varying …   Universalium

  • Die (manufacturing) — For the thread cutting tool, see Tap and die. A die is a specialized tool used in manufacturing industries to cut or shape material using a press. Like molds, dies are generally customized to the item they are used to create. Products made with… …   Wikipedia

  • Glossary of military abbreviations — List of terms, acronyms, information, related to modern armour, artillery, infantry, weapons, and related military subject matter.* AA anti aircraft * AAA anti aircraft artillery Triple A * AAAV Advanced Amphibious Assault Vehicle * AAD Armoured… …   Wikipedia

  • Blade — For other uses, see Blade (disambiguation). Knife blades A blade is that portion of a tool, weapon, or machine with a cutting edge and/or a pointed tip that is designed to cut and/or puncture, stab, slash, chop, slice, thrust, or scrape animate… …   Wikipedia

  • Die grinder — A pneumatic die grinder with a right angle head. A die grinder is a handheld power tool used to grind, sand, hone, polish, or machine material, typically metal but also plastic or wood. They are usually pneumatically driven, although versions… …   Wikipedia

  • M61 Vulcan — Infobox Weapon name= M61 Vulcan caption= An unmounted M61 Vulcan. origin= United States type= Autocannon is ranged= yes service= 1959 present used by= United States/NATO wars= Vietnam War designer= design date= manufacturer= General Dynamics unit …   Wikipedia

  • Fairchild Republic A-10 Thunderbolt II — A 10 redirects here. For other uses, see A10. A 10 Thunderbolt II An A 10 from the 81st Fighter Squadron, Spangdahlem Air …   Wikipedia

  • .30-06 Springfield — Infobox Firearm Cartridge name=.30 06 Springfield caption=From left to right 9.3x62mm, .30 06 Springfield, 8 x 57 IS, 6.5 x 55 and .308 Winchester cartridges. origin=flagcountry|United States type=Rifle service=1906 used by=USA and others… …   Wikipedia

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”