tailieunhanh - Volume 07 - Powder Metal Technologies and Applications Part 11

Tham khảo tài liệu 'volume 07 - powder metal technologies and applications part 11', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | hỉ tkT In this equation t is the part thickness k is the compression ratio and k q qa where q is the part required compaction density and 7a is the apparent density of the loose powder. If the fill height is greater than the maximum fill height that can be accommodated in the press selected on the basis of the compacting load required a larger capacity machine should be selected which has the required fill height capacity. Powder Metallurgy Presses and Tooling Revised by John Porter Cincinnati Incorporated Tooling Systems High-production P M compacting presses are available as standard production machines in a wide range of pressing capacities and production rate capabilities. Presses are designed to produce parts of a specific classification as discussed previously. Single-action tooling systems generally are limited to production of class I parts. During the compacting cycle the die core rod and one of the punches usually the lower punch remain stationary. Compacting is performed by the moving punch which is driven by the action of the press. One or more core rods may form any through holes in the part. During ejection the upper punch moves away from the formed part and the part is ejected from the die by the lower punch. The core rod Fig. 7 is stationary and the part is ejected from the die and core rod simultaneously. On some presses the core rod is arranged so that it is free to move upward float with the part as it is ejected. The compacted part experiences slight elastic expansion on ejection from the die which causes the part to free itself from the core rod. The core rod is then free to move downward to the fill position. This floating core rod arrangement reduces ejection forces and core rod wear. upper punch Fig. 7 Compacting sequence utilizing single-action tooling. Dashed line indicates motion of lower punch. I Double-action tooling systems primarily are used to produce class I and II parts. Force is applied to the top and bottom of the part .