Page:EB1911 - Volume 27.djvu/38

of steps have to be made, and recesses, or flanges, or other features produced. Out of the demands for this more complicated work, as well as for plain bolts and studs, has arisen the great group of turret or capstan lathes (Fig. 31) and the automatics or automatic screw machines which are a high development of the turret lathes. Turret Lathes.-The turret or capstan (fig. 32) is a device for gripping as many separate tools as there are distinct operations to be performed on a piece of work; the number ranges from four to as many as twenty in some highly elaborated machines, but five or six is the usual number of holes. These tools are brought round

FIG. 31.—Turret, Lathe.;f (Webster & Bennett, Ltd., Coventry.) A, Bed. N, Bearing to feed the work through mandrel (constituting the B, Waste oil tray. wire or bar feed). A collar is clamped on the work, and is C, Headstock. pushed by the bearing N at each time of feeding D, Hollow mandrel. 0, Cross-slide.

E, Cones keyed to D. P, Hand-wheel operating screw to travel 0 F, Split tapered close-in chuck, actuated by tube G. Q, Turret-slide. H, Toggle dogs which push G. R, Cross-handle moving Q to and fro J, Coned collar acting on H . S, Turret or capstan. K, Handle to slide ] through sleeve on bar L. T, U, Sets of fast and loose pulleys, for open and crossed belts. M, Rack slid on release of chuck, moving bearing N iorward. V, Cone belted down to E on lathe. in due succession, each one doing its little share of work, until the F 'f cycle of operations required to produce the object is complete, I the cycle including such operations as turning and screwing, roughing and finishing cuts, drilling and boring. Severance of the finished piece is generally done by a tool or tools held by a cross-slide between ~a . the headstock and turret, so termed because its movements take 4 © ' place at right angles with the axis of the machine. This also “ E often performs the duty of “ forming, ” by which is meant the shapf ing of the exterior portion of an object of irregular outline, by a ¢, ~ ° tool the edge of which is an exact counterpart of the profile required. W @ %//K The exterior of a cycle hub is shaped thus as also are numerous -', / 1

é ' handles and other objects involving various curves and shoulders, &c. The tool is fed perperidicularly to the axis of thi rotatf ing work and completes out ines at once: i this were one in /}, -" ' grdinary laithes much tedious manipulation of separate tools would I in »

.- /J I, e mvo ve,

- ...., ' — x ' Automattcs.-Bu t the marvel of the modern automatics (figi 333 mn-I; ' lies m the mechanism by which the cycle of operations 1s ren ere —»-, J= absolutely independent of attendance, beyond the first adjustments 5 E A 5' ~, "~-t and the insertion of a fresh bar as often as the previous one becomes I i " If used up. The movements of the rotating turret and of the cross@; slide, and the feeding of the bar through the hollow, spindle, take I place within a second, at the conclusion of the operation preceding. N These mgvementls alx;e elgfected bky a settl of rnechangm independent

.S & of that whic the eadstoc spin le is rotate, viz. y cams

in, M Q* or cam cliums on a horizontal cam shaft, or other equivalent D device, differing much in arrangement, but not principle. Movements are hastened or retarded, or pauses of some moments may v ' f ensue, according to the cam arrangements devised, which of course C ' have to be varied for pieces of different proportions and dimensions. FHL 32 p|an of Set of Tu, -, -et T0015 (A Herbert' Ltd) But when the machines with their topls are once set up, they will run for days or weeks, repeating precisely the same cycle of opera-A, Turret. D, Box tool carrying two cutters tions; they are self-lubricating, and only require to be fed with B, Tool for first operation or for third operation, rough gteslillengths of bar and to have their tools lreshzarlpenedi occasionally. chucking. turning. t ese automatics alone t ere are somet ing i e a ozen istmct C, Cutting tools for second E, Similar tool for fourth opera- types, some with their turrets vertical, others horizontal. Not operation, starting or point- tion, finish turning. only so but the use of a single spindle is not always deemed suiiiing. F, Screwing tools in head for ciently economical, and some of these designs now have two, three final operation of screwing.,

and four separate work spindles grouped in one head.