抄録
The clay body processed as usual was pugged with a laboratory pug mill. The pugged mass was then subjected to uniform pressure in a cylinder filled with oil by compressing the latter with a piston whose displacement being measured by a dial gauge. From the pressure-displacement curve thus obtained the quantity of air contained within the mass was estimated.
From the results it was concluded that
(1) the quantity of air occluded decreases in proportion to the degree of evacuation.
(2) the evacuation is effective in inverse proportion to the thickness of clay-slab supplied to the vacuum chamber of the mill.
(3) the time necessary for the evacuation is the scores of seconds, generally less than 30 seconds.
It was observed that the operation of vacuum pug mill under comparatively higher pressure rather leads to the increase of the quantity of air. This tendency was found to be true, for example, to the pressure as low as 500mmHg. Hence for the effective de-airing the evacuation lower than 500mmHg would be necessary.
