Page:Popular Science Monthly Volume 91.djvu/901

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Barking Wood by Machinery

The logs of wood are made to rub against each other and scrape the bark off automatically

��WOOD barking today is not what it used to be — a hand process carried out with long sharp knives. One or two hollow steel drums are all that are now seen in the modern barking mill, — drums that remove the bark from many tree trunks at one time.

Perhaps a dozen huge trees are cut up into a thousand pieces. These are fed into one end of the horizontal, rotating drums. The angle irons, which make up the steel framework, grip the edges of the logs, tumbling them about so that they rub against one another. The bottom of the drum is immersed in a tank of water, so that the bark is soaked and easily peeled off. Fresh logs fed into the drum on con- veyors push the barked logs on to dis- charge-conveyors at the opposite end of the drum.

The con- struction of this barking drum is as in- genious as is its principle. Since j t would not do to immerse the bearings of the drum in the water, the drum is suspended on endless chains which run over pul- leys mounted 1 1 { . , The revolving drum which

high and i ogs peel off ^^ own bark

��dry" on the top of the barking machine structure.

There is little about the operation that requires attention. In fact, one operator now takes the place of nine skilled whittlers. Altogether, the result in a fair-sized mill which turns out six or seven hundred cords of barked wood in a day, is a saving over the hand method of about three hundred thousand dollars a year.

Strangely enough, though theory would seem to indicate that sharp points mounted radially in the inside of the drum would be more efficient than blunt angle irons, such points are not the choice of experience. While these points would peel off the bark in considerably less time than the irons do, they would also dig into the "flesh" of the wood. The resulting saving in time

would be more than offset by the decrease in the commer- cial value of the wood. For this rea- son, it has been found best not even to grind down the edges of the angle irons. As a result the wood comes out

makes a thousand or more - .

It is operated by one man bruise.

���BarK scrapers

���'conveyor

��1 Barbed conveyor to boiler room

��Perforated plate

��Diagram show- ing the principle and operation of the wood-bark- ing machine. A dozen huge trees cut up into a thousand or more pieces may- be fed into the drum at one time, tumbled about and soaked in water and finally dis- charged clean

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