Fig. 21. Second Operation on Bevel Gear Blanks
The second and final operation on this blank is shown in [Fig. 21]. The work A is held by a special driver plate attached to the faceplate of the machine. This driver plate has two pins which engage holes drilled in the gear blank and prevent it from rotating. The blank is also held by a bolt B which forces a bushing against the cylindrical end. First, the broad beveled side which is to be the toothed part of the gear, is rough-turned by toothed cutters C, and a recess is formed in the end of the blank, by a turning tool in this same tool-holder. A similar tool-holder E, having finishing cutters, is then used to finish the bevel face and recess. The other tools seen in the turret are not used for this second operation. The rear bevel is roughed and finished by tools and held on the cross-slide.
Shell Turning Operation in Flat Turret Lathe.—The “flat turret lathe” is so named because the turret is a flat circular plate mounted on a low carriage to secure direct and rigid support from the lathe bed. The tools, instead of being held by shanks inserted in holes in the turret, are designed so that they can be clamped firmly onto the low circular turret plate.
Fig. 22. Sectional View of Tapering Mold Shell which is turned in
Hartness Flat Turret Lathe, as illustrated in [Figs. 23] to [27], Inclusive
An interesting example of flat turret lathe work is shown in [Fig. 22]. This is a steel shell which must be accurately finished to a slight taper, both inside and out, threaded and plain recesses are required at the ends, and, in addition, one or two minor operations are necessary. This work is done in the Hartness flat turret lathe, built by the Jones & Lamson Machine Co. The shells are turned from cold-drawn seamless steel tubing, having a carbon content of 0.20 per cent, and they are finished at the rate of one in nine minutes. The tubing comes to the machine in 12-foot lengths, and the tube being operated upon is, of course, fed forward through the hollow spindle as each successive shell is severed.