Copper, Brass, and Bronze Surfaces by L. William Zahner

Copper, Brass, and Bronze Surfaces by L. William Zahner

Author:L. William Zahner [Zahner, L. William]
Language: eng
Format: epub
ISBN: 9781119541684
Publisher: Wiley
Published: 2020-04-07T00:00:00+00:00


C11000 Copper

C21000 Brass

C23000 Brass

C24000 Brass

C38500 Brass

C65500 Bronze

FIGURE 5.9 An extrusion must fit within a circle whose size is determined by factory capability.

The Extrusion Process

All extrusion processes begin with a cylindrical billet of solid copper. The billet is composed of a select alloy of copper created to specification at the Mill source. Several of the copper alloys have small amounts of lead in them to facilitate the hot shaping of the metal as it extrudes. The billet is often cut down from a larger cylindrical casting called a “log.” Billets can range in length from 660 mm (26 in.) to as large as 1830 mm (72 in.) and in diameter from 76 mm (3 in.) to as large as 838 mm (33 in.) depending on the equipment set to receive them. The larger diameters require significant tonnage in the press used to push the heated copper through the die. The maximum diameter is 100 mm (4.5 in.).

The billet of metal is heated and the equipment (the press and die) are preheated. The billet temperature is brought up just short of the melting point of the copper alloy. Pressure is applied to the end of the billet by means of a special hydraulic extrusion press. The pressure can range from 100 tons to as high as 15 000 tons depending on the equipment. This pressure pushes the hot billet up against the steel die. As the pressure builds, the semiplastic copper flows through the die opening and conforms to the shape cut into the die.

As the hot extrusion exits the die it is run out onto a set of roller tables. As it is brought out on the table it is cooled by a water quench or air wash. The extrusion may twist due to differential cooling or out‐of‐balance stress due to the shape. It is cut to length to fit into a stretching device. The length is stretched 1–3% to eliminate the stress and straighten the extrusion. The ends may be trimmed to a finish standard length.

Most copper extrusions are thick and compact. Thin, spindly forms will not extrude well due to the intense heat. They can collapse and bend.



Download



Copyright Disclaimer:
This site does not store any files on its server. We only index and link to content provided by other sites. Please contact the content providers to delete copyright contents if any and email us, we'll remove relevant links or contents immediately.