ABSTRACT
Figure 41 A vertical press with the Glover tray system which provides a liquidmetal supply to the continuous press container [331]. (Courtesy of Dr. S. A. Hiscock.)
screw housing, it is solidified. The solid lead is forced into the die block at pressures of up to 200 MPa. The die block forms the lead into a tube as it passes through the extrusion core and die. At this point, the material is at a temperature of 2ooaC. As the lead sheath is applied to the cable, it is immediately cooled to prevent damage to the cable. The concentricity and thickness are controlled to within 0.05 mm. The progress of the sheath through the die is sufficient to move the insulated cable core with only moderate pressure being exerted on the core itself. In the Hansson-Robertson extruder, the lead is kept molten for much of the screw length, thus reducing the stress on the tooling. Tables 4-6 provide operational data for the extrusion of lead alloy cable sheathing in Hansson-Robertson extruders [339]. Table 7 provides a list of Hansson-Robertson extruders currently operating worldwide [340]. The screw machines work well with lead and
Figure 42 A feeding system to provide liquid metal to the continuous lead press container under vacuum (331). (Courtesy of Dr. S. A. Hiscock.)
Figure 43 An overview of the Hansson-Robertson cable-sheathing press [331]. (Courtesy of Dr. S. A. Hiscock.)
10 25 30-60 500 18 40 30-60 1000 30 70 30-60 1000 60 120 30-60 1000
Table 5 Output Rates and Range of Diameters of Lead Cables Extruded in Hansson-Robertson Extruders [339]. (Courtesy of H. Folke Sandlin AB, Sweden.)
Machine size
Output" Die block Lead tube (kg/ size outer diameter min) (in.) (rom)
23-25 7-1/2 6-50 9 9-85
11 10-110 32-35 9 9-85 36-38 liB 9-85 32-35 11 10-110 32-35 12-1/4 85-125 32-35 13-1/4 85-150 50-55 IIBL 9-85
IlL 10-110 12-1/4 85-125 13-1/4 85-150
Table 6 Extrusion Rates and Die Block Temperatures for Hansson-Robertson Extruders for Different Lead Alloys [339]. (Courtesy of H. Folke Sandlin AB, Sweden.)
Output Die block temperature
Material (kg/min) 3RT 3R 4R Pure Pb Max. 210 200 265 E' 23-26 205 195 255 E 16-18 205 195 255 I/2C 20-25 215 208 265 B' 14-16 190 180 250 B 10-14 185 170 245 PbTeCu 20-25 218 212 267 F3 16-18 195 180 265 PbCu 25-30 210 200 265 PbTe 25-30 205 195 260
Table 7 List of Hansson-Robertson Extruders Currently Operating Worldwide [340]. (Courtesy of H. Folke Sandlin AB, Sweden.)
Extruder model (machine size/
Continent/country die size in inches) No. of units'
North America Canada 5/11 I Mexico 3/9 2 United States 4/9 1
4/11 I 5/11 10 5/11 L I
South America Brazil 3/9 2
Africa Algeria 3n 1
4/9 I South Africa 3n 1
3/9 I 4/9 1
Egypt 3/9 2 4/11 I
Asia China 4/11 9
12 1/4 1 13 1/4 1
India 3/9 2 4/11 2
Iraq 4/9 2 Malaysia 3/9 1
3/11 I Pakistan 3n I Korea 3/9 2
4/11 2 Japan 3n 2
3/9 1 4/9 4 4/11 11 4/13 1/4 I 5/11 3
12-1/4 5
Table 7 Continued
Extruder model (machine sizel
Continent/country die size in inches) No. of units' Australia
Australia 3/9 2 4/11 1
New Zealand 3/9 1 Europe
Austria 3/9 1 4/9 I 4/11 3
Belgium 3(7 1 4/11 1
Bulgaria 3/9 1 4/11 2
CIS 3/9 5 4/9 3 4/11 9 5/11 11
13-1/4 1 Czechoslovakia 3/9 1
4/11 5 Denmark 3(7 1
4/11 2 Finland I 1
3(7 2 3/9 I 4/9 3 4/11 I
France 3(7 6 3/9 4 4/9 2 4/11 7 5111 1
Gennany 1(7 1 3/9 4 4/9 2 4/11 8
12-1/4 1 Great Britain 3(7 1
3/9 4 4/9 7 4/11 8 5111 2
Table 7 Continued
Extruder model (machine size/
Continent/country die size in inches) No. of units' Greece 3/9 7
4/11 I Netherlands 3/7 2
3/9 1 4/9 2 4/11 4 5/11 1
12-1/4 1 Hungary 4/11 1 Italy 3/9 6
4/9 3 4/11 6 5/11 4
Northern Ireland 4/11 I Norway 3/7 I
3/7 1/2 I Poland 3/9 2
4/11 2 Rumania 4/9 2 Spain 4/11 2 Sweden I 1
3/7 3 4/9 4 4/11 7 5/11 1
Switzerland 3/7 2 4/11 3
Turkey 3/11 I Yogoslavia 3/9 1
4/9 2 4/11 1
Figure 45 Pirelli screw extruder for cable sheathing [331]. (Courtesy of Dr. S. A. Hiscock.)
Processing of Lead Products 371
produce desired fonns by other metal working processes. Rolling is the principal method of producing sheets and foils of lead. In rolling plastic defonnation occurs by passing the material between the rolls. Rolling involves compression of material between the rolls under nearly plane strain conditions. Depending on the number of rolls in a given rolling stand, the rolls are classified as a 2-high, 3-high, 4-high, cluster (Sendzmir), or planetary type mill. Two high-rolling mills are employed in the production of lead sheet.
