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.
Such a furnace as has just been described will, if properly built, and with occasional repairs to the fire brick lining, last many years. The author knows of one which was built twenty years ago that is in serviceable condition at the present time.
On the opposite side of the central columns is located the group of machines for roughing out stock, the first being a heavy cutting-off machine capable of taking in stock up to six inches in diameter and cutting it off to any required length. In this machine there should be two tools fed automatically, and the machine should be provided with a convenient speed-changing device whereby the surface cutting speed may be maintained constant at all diameters, as this latter feature will materially increase the output of the machine.
Fig. 126. Rear Elevation of Annealing and Case-hardening Furnace.
Fig. 127. Section through Fire Box, etc., of Annealing and Case-hardening Furnace.
Fig. 128. Longitudinal Section of Annealing and Case-hardening Furnace.
Next to this machine are two cutting-off machines of a capacity for 4-inch stock and arranged similarly to the larger machine. They are so placed as to be conveniently operated by one man.
Next to these machines are two power hack saws, provided for cutting off square and flat stock. These should carry from 12 to 15 inch saws, and while apparently slow-working machines are capable of cutting off a large quantity of stock in proportion to the labor cost of attendance.
Located near the large cutting-off machine is the cold saw, which will serve for stock or forgings beyond the capacity of the cutting-off machine or the power hack saws, and will often save much valuable time in finishing up a forging. The saws, in these machines are from 12 to 40 inches in diameter, the former size cutting off stock up to 3« inches in diameter, and the latter handling 13-inch stock. For this case the saw should be 20 inches in diameter, and capable of cutting off 7«-inch stock. There are many of these saws in the market and apparently not very much choice between them, all conditions being considered.
The shear, located next to the cold saw, is not generally as much used as before the power hack saw came into notice, yet in certain classes of rough work it is very useful and operates quickly. It should be able to cut off round stock up to one inch, square stock to the same size, and flat stock to half inch by two.
In the heavy turret lathe much work may be roughed out from the bar and sent to the machine shop in a more satisfactory condition than if it had been forged, and at the same time it will do the work more economically. It should take in stock up to 3 inches in diameter and be provided with a heavy, open, hexagonal turret, bored so as to allow the stock to pass entirely through it if necessary. If should also be provided with heavy roughing tools somewhat similar to box tools, as well as a heavy cutting-off slide adjustably supported on the bed.
The forge lathe, located next to the turret lathe, will be useful in rough-turning spindles and similar heavy work, and doing it much cheaper than forging the work down to close dimensions. It should be built for cuts of 6 or 8 to the inch, and a cutting speed from 100 feet per minute and slower.
A short work bench and vise is provided at each end of the line of forges for the convenience of the blacksmiths, and a much longer one on the opposite side for the men running the machine tools, which should have three vises upon it.
A supply of steam will be needed for the steam hammers, and may be brought from the power house in a conduit, the pipes being properly protected by a non-conducting covering to prevent, as far as possible, the loss of heat. But these hammers may be operated by compressed air, which will not be subjected to such loss. And as power will be required to run the line shafting driving the various machines, it may be more economical to bring in a current of electricity with which to drive one or more motors, by which the line shafting may be driven and from which a small air compressor may be operated, thus bringing the power within the building and under the control of the foreman in charge of it. This plan would seem more advisable than the other. If an air compressor is used it may be located between the shear and the scale, and the reservoir connected with it placed directly overhead.
Fig. 129. Section through Heating Chamber of Annealing and Case-hardening Furnace.
If an electric motor is used to drive the line shaft it will be convenient to place it overhead and near the center of the shaft, on a platform erected for the purpose, rather than to place it on the floor level, where it will be subjected to dirt and accidental injury.
A jib crane may be erected to serve the large steam hammer and an overhead trolley for the smaller one, the latter being the more economical of the two, and will be found nearly as convenient for comparatively light weights. The I-beams carrying the trolley and hoist should run from a point nearly over the center of the forge to a point close to the left side of the hammer, as seen on the plan.
Pneumatic hoists may be conveniently used not only on this trolley but in a similar way at the forge lathe and over some of the other machines for handling heavy bars. They work quickly, are easily handled, and when necessary may be readily moved from place to place.