42,) which will thoroughly mix its various ingredients, and work the
whole into a homogeneous mass, ready for the tile machine. The _pug-mill_
is similar to that used in brick-yards, only, as the clay is worked much
stiffer for tiles than for bricks, iron knives must be substituted for the
wooden pins. These knives are so arranged as to cut the clay in every
part, and, by being set at an angle, they force it downward toward the
outlet gate at the bottom. The clay should be kept at the proper degree of
moisture from the time of tempering, and after passing through the
pug-mill it should be thoroughly beaten to drive out the air, and the
beaten mass should be kept covered with wet cloths to prevent drying.
*Moulding the Tiles.*--Machines for moulding tiles are of various styles,
with much variation in the details of their construction, but they all act
on the same general principle;--that of forcing the clay through a
ring-shaped aperture in an iron plate, forming a continuous pipe, which is
carried off on an endless apron, or on rollers, and cut by wires into the
desired lengths. The plates with the ring-shaped apertures are called
_dies_; the openings are of any desired form, corresponding to the
external shape of the tiles; and the size and shape of the bore, is
determined by the core or plug, which is held in the centers of the
apertures. The construction of the die plates, and the manner of fastening
the plugs, which determine the bore of the tiles, is shown in Fig.
Pages:
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214