MACHINE FOR MOULDING ROOFING-TILE FROM PLASTIC CLAY.
The machine shown in Figs. 249 to 252 is especially de signed for the formation of roofing-tile from plastic clay.
The main features of the invention consist of a series of sim ilar lower dies attached to a revolving horizontal table, and brought successively beneath the upper dies ; the latter consist of two parts, viz., an outer shell, which forms the edge of the tile, and an upper die, sliding within the shell, and which forms the upper surface of the tile, each attached to suitable slides, and adapted to move independently with a vertical reciprocat ing motion. In combination with these elements, and moved by the same machinery, is also an automatic feeding apparatus.
Figs. 249, 250 and 251 represent, respectively, a side eleva tion, a front elevation, and a plan of the tile-machine ; and Fig. 252 a perspective view of the dies and shell on an enlarged scale.
The main part of the machine is attached to and supported by the frame A, which stands upon the legs B B. Journaled in the upper part of the frame is the shaft C, turned by the pulley D. On the front of this frame A are cast or attached suitable guides e e, within which moves the slide E, carrying on its lower end the upper die F, and moved with a vertical recip rocating motion by the cam G. Upon the outside of the guides e e is fitted another slide H, also having a vertical reciprocating motion, moved by the cam I, and carrying the shell 7. The lower dies K K are attached to the platform L, which is keyed to and turned by the shaft M. The platform L rests upon an annular bed N, attached to and supported by the frame A, and the upper surface thereof, being planed smoothly, affords a sliding seat, upon which the platform L revolves.
In practice it will be found convenient to have both the an nular bed N and lower die F cast hollow, and charged with steam, when in use, to facilitate the separation of the dies from the tile after the latter is pressed. Upon the shaft C is an ec centric-cam 0, connected to a crank on one end of the shaft Q by the rod P; and upon the opposite end of the shaft Q is a crank-arm S, which is connected by a rod s to, and moves a loose collar T on the shaft M.
This collar T carries a pawl t, which engages the ratchet U on the shaft M, and thereby the cam 0 causes, at each return stroke of the upper die F and shell 7, a partial revolution of the platform L, sufficient to bring one of the dies K in position beneath the upper die and shell.
In operation, one of the lower dies K being in position beneath the upper die, with a portion of clay thereon, by the action of the cams / and G, the shell .7 first descends and sur rounds the die K, to which it is accurately fitted. The upper die then descends within the shell and presses the clay into the desired shape, all excess of clay escaping through the holes i i in the ends of the shell .7. The upper die still remaining on the clay, the shell .7 first ascends ; the upper die F then as cends; a partial revolution of the platform then ensues, and the operation is repeated.
Especial attention is called to the arrangement of the lower die, shell, and upper die, and the relative motion of the latter two at the time of forming the tile. The upper die at no time
entirely leaves the interior of the shell 7. When the shell 7 descends upon the die K, the three parts form a closed mould, with the unpressed clay therein.
By causing the shell to rise first, it cuts off two streams of surplus clay at the holes i i, leaving the edges of the tile smooth and clean cut, and permits the upper die to ascend without tearing the green tile, which could not be done if the shell 7 remained down.
In practice it is found that, with every precaution to prevent it, there are always incorporated in the pressed tile particles of compressed air, which, by its expansive force, would, if the die F remained at its extreme pressure when the shell was re moved, force the clay out laterally between the upper and lower dies, thereby destroying the line and smoothness of the edge of the tile. This is avoided by using an eccentric-cam G, to operate the upper die, whereby the upper die begins slowly to ascend the instant after its extreme pressure, thereby permit ting the clay to expand upward by the time the shell ascends above it.
Nail-holes are made in the tile as follows : Upon the shell .7 are two standards V V, the upper angle whereof is so high as not to interfere with the greatest separation of the upper die and shell. Projecting downward from the top of these are pins c c, which pass through holes in the upper die, and of such length that their lower ends shall rest against the face of the lower die K when the shell J is at its extreme downward stroke. Their operation will be readily understood from the foregoing description of the press as they follow the motion of the shell Y.
The feeding device consists of a hollow, open cylinder W, supported over one of the lower dies when the latter is at rest, as shown.
Across the bottom of this cylinder slides a plate X, sup ported by an arm Y, which swings horizontally on the shaft M. In this plate is a depression d, as large as the interior circum ference of the cylinder IV, the side of said depression toward the centre of the plate being open, and the edge of the plate at that opening sharpened to form a knife. This plate is caused to oscillate across the lower end of the cylinder W, by a pitman attached to the crank-arm S.
In operation, a roll of tempered clay is placed in the cylinder. By the action of the arm S, in revolving the platform L, the depresssion in the plate X is brought beneath the cylinder, and into this the roll of clay settles, when, by the return of the plate, a slice of clay is cut off, and falls on the die below.
Fig. 253 shows the common form of tile-barrows, which are similar to the brick-barrows, with the exception that they are wider at the front, the back or "dash" is higher, and the wheel is covered. Fig. 254 shows the form of a tile-truck designed to carry tiles from the machine to the drying-sheds ; the usual size of the platform is 28x72 inches, and being mounted on two wheels is not easily upset.