Powder compaction pressing process for capacitor anodes
View Patent ↗A powder compaction process using opposed rib and channel punches which are interleaved and a production method are used to produce capacitor elements having a uniform compaction density and which are free of surface imperfections.
1. A method of making a capacitor element with opposed indentations in each laterally opposite side defining ribs and channels, comprising the steps of:
providing a press with a compression chamber, a set of opposed rib punches, a set of opposed channel punches interleaved with said rib punches shiftable between non-compaction and compaction positions, and power means operable to move said punches between said non-compacting and compacting positions,
the ratio of the distance between said opposed rib punches in the non-compacting position to the distance between said opposed rib punches in the compacting position being equal to the ratio of the distance between said opposed channel punches in the non-compacting position to the distance between said channel punches in the compacting position,
using said power means to position said opposed rib punches and said opposed channel punches in the non-compacting position,
filling said chamber with valve metal powder,
using said power means to compress said valve metal powder to form a capacitor element by simultaneously moving said channel punches and said rib punches from the non-compacting positions to the compacting positions at speeds proportional to said ratio distances they move in forming said element, and
using said power means to retract said punches from the compacting positions to the non-compacting position.
2. The method of claim 1 in which said channel punches are retracted before said rib punches during the step of retracting said punches.