The turret again automatically recedes and indexes, thus locating bar E and turning tool G in the working position. The hole is then finish-bored by tool E and the hub is finish-faced by blade F; at the same time the rim is finish-turned by tool G and the sides are finish-faced to the proper width by two tools held at the rear of the cross-slide. The turret automatically recedes and indexes a third time, thus locating the flat-cutter reamer-bar H in the working position and then the hole is reamed to the required diameter. This completes the cycle of operations. The total time for machining this flywheel is forty minutes.
Fig. 41. New Britain Multiple-spindle Automatic
Chucking Machine of Single-head Type
Automatic Multiple-spindle Chucking Machine.—An example of the specialized machines now used for producing duplicate parts, is shown in [Fig. 41]. This is a “New Britain” automatic multiple-spindle chucking machine of the single-head type and it is especially adapted for boring, reaming and facing operations on castings or forgings which can readily be held in chuck jaws. This particular machine has five spindles, which carry and revolve the tools. The work being machined is held stationary in the multiple chuck turret A which holds each part in line with one of the spindles and automatically indexes, so that the work passes from one spindle to another until it is finished. The turret then indexes the finished piece to a sixth or “loading position” which is not opposite a spindle, where the part is removed and replaced with a rough casting. Each pair of chuck jaws is operated independently of the others by the use of a chuck wrench. These jaws are made to suit the shape of the work.
When a single-head machine is in operation, the turret advances and feeds the work against the revolving tools so that a number of pieces are operated upon at the same time. The turret is fed by a cam drum B. Cam strips are bolted to the outside of this drum and act directly against a roller attached to the yoke C which can be clamped in different positions on the spindle D, the position depending upon the length of the work. On the opposite end of the turret spindle is the indexing mechanism E. An automatically spring-operated latch F engages notches in the rim of the dividing wheel, thus accurately locating the turret. The turret is locked by a steadyrest G, which, for each working position, automatically slides into engagement with one of the notches in the turret. This relieves the indexing mechanism of all strain.
This type of machine is also built with two spindle heads, the double-head design being used for work requiring operations on both ends. When the double-head machine is in operation, the revolving spindles and tools advance on both sides of the chuck turret, the latter remaining stationary except when indexing. The feed drums on the double-head machine are located directly beneath each group of spindles.
