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side of die D, thus turning the semi- the sides ana ends corrugations can be formed tub inside out, and through this felt which are the wrinkles resulting inverted redrawing creating the finished from the drawing operations. These form of the tub, the roll-shaped rim being must be eliminated, and it is for this formed by the passing of the metal purpose that the machine shown in Fig. 3 around the lower curved edges of die D. was designed. This third press is the The tub is then completely drawn and is most important device used in the entire removed from the press by the ejector, process—in fact, is the main feature of in an inverted position as shown in Fig. 2. the works, and is well named "the
Although the tub has its finished size rocker-roller press.” It is a gigantic and shape, by passing one's hand along machine, weighing 175 tons, exerting simultaneously vertical, lateral, and di- foundation, is twenty-one feet long and agonal pressures of sufficient intensity so ten feet wide. The press consists of a to change the flow of the metal as to re- frame, having a series of five plungers, sult in a perfectly smooth surface each capable of exerting a pressure of throughout the entire tub. At the same 200 tons, and being so arranged that this time the metal is set so that in after pressure can be brought to bear in three heating, which of course is necessary in directions. The vertical plunger carries the enameling process, there is no dis- a rocker, which permits the oscillatortion due to strains in the metal releas- tion of the "roll” or punch suspended at ing themselves under the heat. This is accomplished by reason of the fact that in the rockerroller press the metal in the irregular shape of the tub is rolled out just as evenly at every point and on the same principle as is a flat sheet when pressed between a pair of rolls.
The rocker - roller press, the only one of its kind ever constructed, is indeed a wonderful machine, and was built by a Philadelphia firm. It stands twenty-eight
FIG. 6. THREE HOLES PUNCHED AT ONCE. feet in height from its
Feed and overflow openings provided for.
its extreme lower end. Attached to each will be observed that the "roll" is someside of the rocker is a hydraulic buffer what smaller than the die into which it plunger, and immediately above the “roll" fits, and that its shape does not conform two saddles are placed so as to come ex to the shape of the tub longitudinally. actly in contact with the buffer plungers When it is brought down into the center
of the tub and the proper pressure exerted it fits on a knife edge transversely across the center of the tub. One of the horizontal plungers is then placed in operation and the bed plate is pushed sideways, with the result that a rolling action takes place within the die, the “roll" slowly traveling with the bed plate as a result of the pressure of the horizontal plunger. The shape of the “roll" is such that its end fits snugly into the end of the tub at just about the time when the saddle on the opposite side of the plunger comes in contact with the buffer ram, as shown in Fig. 4. The simultaneous pressure of the three plungers is then brought into play and just enough additional pressure is given by the horizontal plunger to overcome the pressures of both the vertical and buffer, with the result that the "roll” continues to roll the metal perfectly smooth right out to the rim of the tub. The horizontal plunger on the opposite side of the machine is then brought into action, and the same process smooths out the opposite end of the tub. The small vertical plungers on each side of the bedplate shown in the illustration were designed for clamping purposes, but it has been found unnecessary to use them. The multiple-drawing operation requires
about six or seven minutes. Fig. 5. Punch which ProviDES HOLE FOR WASTE-Pipe.
After the tub leaves the rocker-roller
press it is taken to a hydraulic punch when the oscillating end of the vertical shown in Fig. 5, where in a single moveplunger is swung over sufficiently to ment of the plunger the hole in the boteither side. At each side of the machine tom of the tub to which the waste pipe at its base there is a horizontal plunger is attached is punched. and a groove surhaving a capacity of 200 tons pressure. rounding it is countersunk. The tub is Both of these are connected to a bed then taken to a horizontal punch, as plate or die box, which when actuated shown in Fig. 6. Here three holes are by the horizontal plungers travels back punched simultaneously in the end of the and forth like the bed plate of a planer. tub. These holes are for the faucets In this bed plate there is a die into and the overflow waste pipe. which the tub about to undergo the Following this operation comes the finishing or smoothing out process is cleaning. Wire brushes and sand blast placed.
are used for freeing the metal from The vertical plunger is then lowered scale and dirt and the tubs are ready for until the "roll” rests on the inside of the the enameling room. Here the tubs are tub, as shown in Fig. 4. The downward first given a slush coat, which is applied pressure is then brought into play. It both inside and out and by means of a
brush, as shown in Fig. 7. They are then fired, being conveyed or “shipped" to the muffle furnace by means of a fork suspended by a chain from a jib crane, as shown in Fig. 8. After the firing the hot tubs are placed in the cradle (Fig. 8) and here the “dredging” operation is performed. This consists of sifting the porcelain over the inside surface of the tubs. The porcelain, which is in the form of a very fine powder, is placed in the sieve at the end of the “dredge.” At the opposite end of the handle there is small pneumatir hammer which is set in motion, with the result that a slight steady vibration is given the “dredger," causing the porcelain to fall in a thin even stream. As the operators move the “dredges” about, another man manipulates the cradle by means of handwheels, as in Fig. 8, so that the porcelain may fall on the sides and ends of the tubs. Another firing melts the porcelain powder so that the inner surface of the tubs obtain
the hard glossy finish of the porcelain tub. There are three of the muffle furnaces having a capacity of seventy-five tubs each a day. Coal and coke are used as fuel. Another large furnace is used for making the porcelain, the balance of the equipment in this department consisting of grinding mills, dryers and inixers.
The hydraulic plant consists of three pumps having capacities of 2,000, 1,200 and 300 gallons per minute. Each of these pumps into an accumulator. There is a 75-kw.generating set used in lighting the plant and driving the few machines that are not hydraulically operatei. An air compressor furnishes the air used in the dredges in the porcelaining department. An annealing furnace used in connection with the dredging operation has a capacity of 30 tubs an hour. The furnace is large enough to hold four tubs, and as they are placed in it at one end and taken out at the other a tub remains under the heat for just eight minutes.
things that will make this decade remarkable and in this manufacture of a useful household article, the inventor's genius has worked a real marvel. The most remarkable feature in nearly all manufacture is the work of the machine rather than the product and in many cases it is the machine alone which makes the inventor's control of the
product possible. In no Fig. 8. Tue TUBS ARE HANDLED BY MEANS OF A GREAT FORK, While PASSING
department of work is
the human mind exhibitThe wonderful progress in the art of ing greater advance than in this of laborconstructing machinery, which will pro- saving, time-saving devices for the prodduce results and work economies before uct of household necessities and the field believed impossible is one of the offers great opportunity for economies.
Where Prairie Breezes Blow
Oh, the scent of the sage comes drifting down on the breath of a prairie breeze,
I can see the bulk of a milling herd in the rain-clouds massing black
Oh, for the feel of a braided rein and the plunge of a prairie steed,
-BERTRAND W. SINCLAIR, in The Bohemian.