This section is from the "Modern Machine Shop Construction, Equipment, And Management" book, by Oscar E. Perrigo. Also see Amazon: Modern Machine Shop Construction, Equipment, And Management.
In Fig. 115 the location of the cupolas is shown, and also that of the blower and the blast pipes leading from the latter to the cupolas. A motor is also located in the blower room, which is used to furnish power to run the blower, and also the elevator, the tumbling barrels, and the machines in the chipping room. It may be preferred to have two motors, one to be used only for running the blower, and run for a few hours only when a heat is on, and the other constantly, for driving the machinery above mentioned. These motors may be located side by side in the blower room, as shown. The blower may be placed on the floor, but it is often advisable to locate it overhead, out of the way of dirt and dust and more nearly on a level with the tuyeres of the cupolas, so that some of the curves in the blast pipes may be avoided, as this is a very important matter when the amount of air pressure is to be compared to the power necessary to generate it, as in this class of blowers it is considerably more than is generally supposed, even by good mechanics.
Fig. 115. Plan of Foundry, showing General Arrangement and Equipment.
Fig. 116. Branch Tracks for Cars to run from Elevator to Cupola.
Fig. 117. Rear Elevation of Charging Car.
Fig. 118. Side Elevation of Charging Car.
The motor, or one of them, may furnish power to operate the traveling crane by the old system of a square shaft running the length of the building beside it and so providing power at any point in its travel; but this method is a rather clumsy way to transmit power, and it is a much better system to have the traveling crane carry its own motor, the current being supplied to it by flexible, pendant cables near the wall and out of the way. These should be placed on the side of the building opposite the cupolas, where there will be no obstruction to them and where they will be away from the excessive heat.
The general molding floor of the foundry should have its work so arranged that the spaces outside of the supporting columns will be devoted to the lighter floor work and the bench work, where crane service is not needed. A bench is provided along one side as far as the heating apparatus (which occupies the outer front corner), for bench, or snap flask work. Here it will be found very convenient to use the compressed air hoists for floor work, as it will be in other parts of the plant, as the hoists may be suspended overhead and used not only for drawing the deeper patterns but for turning over flasks, for it is now a demonstrated fact that in compressed air we have a very useful, convenient, and efficient power, which may be utilized in the foundry, perhaps to as good or better advantage than in any other department of the modern manufacturing plant. Its uses are many, and the conveniences with which it may be carried to any part of the floor for individual use, or for the lifting of quite heavy loads, renders it almost indispensable in the routine work of the foundry. The economy of its use may be readily appreciated when it is remembered that an air compressor provided with a cylinder 6 inches in diameter, and a storage tank 3 feet in diameter and 5 feet long, compressing air to 80 pounds per square inch, will furnish ample supply for a dozen hoists lifting 400 pounds or more each.
In drawing patterns, turning small flasks, setting large cores, and similar work, these hoists may be suspended in any desired location, the rubber hose attached bringing a supply of compressed air, easily controlled by a simple valve. These hoists may be suspended from a trolley traveling on an overhead beam, so located as to be convenient to the work. Of course, larger hoists may be used when necessary, and they are quite as effective and economical. Roughly speaking, a hoist with a 3-inch piston should lift 450 pounds; with a 4-inch piston, 800 pounds; with a 6-inch piston, 1,850 pounds; and with an 8-inch piston, 3,300 pounds. A supply of compressed air is very useful in the chipping room, where chipping tools may be very efficiently operated with it, and by its use one man may thereby do the work of at least two, and usually more.
An air compressor may be located in the blower room, as indicated in Fig. 115, and operated by the motor situated there. A cylinder 12 inches in diameter will be ample for the ordinary uses of the foundry floor and for operating such tools as are necessary in the chipping room. It will require a tank about 4 feet in diameter and 8 to 10 feet in length. This may be situated over the air compressor so as not to occupy the floor space. Such a tank should, of course, be constructed on the same lines and of like materials as a steam boiler of similar size, and to withstand the same pressure per square inch. It should be remembered that under ordinary circumstances, if the air compressor is constructed on the plan of the boiler-feed pump, with a steam cylinder and an air cylinder, with one piston common to both, the proportions will be nearly these, viz.: steam cylinder, 6×8 inches, and air cylinder 10 × 8 inches. And also, that 90 pounds steam pressure will give about 65 pounds air pressure, with a piston velocity of 300 feet per minute. These figures are given as nearly correct and easily remembered.
A large variety of molding machines are in the market, many of which are admirably designed to turn out a large quantity of work in a day, and to save much of the manual labor usually necessary. They are, of course, employed on comparatively plain work where the tamping of the sand may be easily done by forcing down upon it a comparatively flat surface. They are usually employed upon the lighter kinds of work.