Experiment on metal powder compaction by differential speed rolling

When differential speed rolling is applied to powder roll compaction, the s tate of stress in the powder or strip between the rolls may be different fr om that found in conventional powder rolling. Differential speed rolling of electrolytic copper powder is conducted under the condition of carefully c ontrolled powder feed rate, oil speed ratios are changed in the range 1.00- 1.33 by choosing combinations of the number of roll evolutions. The rolling load increases on increasing the ratio of powder feed volume to strip spee d and is slightly smaller compared with that of conventional rolling. The d ecrease in the rolling load is about 25% of what is found in conventional r olling, when the roll speed ratio is 1.33. The relative density of the stri p is about 15% larger than that of conventional rolling under the same roll ing load. The strip thickness increases with an increase in the rolling loa d for each roll gap, regardless of the roll speed ratio. (C) 2001 Elsevier Science B.V. All rights reserved.