Example of Work on Automatic Turning Machine.—The piece selected for illustrating the “setting up” and operation of the automatic chucking and turning machine is shown in [Fig. 35]. This is a second operation, and a very simple one which will clearly illustrate the principles involved. In the first operation, the hole was drilled, bored and reamed, the small end of the bushing faced, and the outside diameter finished, as indicated by the sketch to the left. (The enlarged diameter at the end was used for holding the work in the chuck.) In the second operation (illustrated to the right), the enlarged chucking end is cut off and, in order to prevent wasting this piece, it is made into a collar for another part of the machine for which the bushing is intended; hence, the outside diameter is turned and the outside end faced, before cutting off the collar. In addition, the bushing is recessed in the second operation, and the outer end faced. In order to have the surfaces finished in the second operation, concentric with those machined in the first operation, the chuck is equipped with a set of soft “false jaws” which have been carefully bored to exactly the diameter of the work to be held.
The first thing to determine when setting up a machine of this type is the order of operations. In this particular case, the order is as follows: At the first position of the turret, the outside collar is rough-turned and the outer end rough-faced. At the second position, the collar is turned to the required diameter and the outer face is finished. The third face of the turret is not equipped with tools, this part of the cycle being taken up in cutting off the collar with a cut-off tool on the rear cross-slide. The fourth operation is that of recessing the bushing, and the fifth operation, facing the end to remove the rough surface left by the cutting-off tool.
Fig. 36. Front View of Machine set up for the Finishing Operation on the Recessed Bushing and Collar shown in the Foreground and in [Fig. 35]
The tools A and B, [Fig. 36], used for turning the outside of the flange, are held in brackets C bolted to the face of the turret. These brackets are each provided with three holes for carrying turning tool-holders. This arrangement provides for turning a number of diameters at different positions, simultaneously, but for this particular operation, a single cutting tool for each tool-holder is all that is necessary. A special device is used for recessing and will be described later.
Fig. 37. Plate on the Headstock of Machine Illustrated in
[Fig. 32] giving the Speeds and Feeds