'Phr Pratt Whilneq lletek-Culling .310r/rine, shown in Fig. 5, cuts Ill(' Kett 1,1 racks at any pitch, the spindle driving two cutlers, whh(dt 1,10(.k out :mut teeth al the some time. Several racks limy he ent at One lime. The receiving-table has a vertical] odjusinient and a transverse horizontal troverse. The feed is automatic, with self-ael ing adjustohle stop-inotiom The cone is driven by 1i bell, 1111(1 110 11/11('S (110 er-spindle through the medium of gears.
Swasey's Process for Generating and Cutting Spur-Gears. —A new process for generating and cutting the teeth of spur-wheels is thus described by Ambrose Swasey, of the firm of Warner & Swasey, Cleveland, 0. (Trans. A. S. N. E., vol. Iii, 1891): "In the new process, instead of making all gears so that they will run into a rack. the rack is transformed into a and by it the teeth of wheels of any diameter are generated and cut at the same time. Fig. G illustrates a gear generating and cutting engine constructed on this principle. The cutters are shown in position as they appear in the machine when the teeth are cut partly across the face of the wheel. The cutting-spindle and the main spindle which carries the wheel are connected by means of change-gears, the number of teeth to be cut in the wheel determining their proportion, on a similar principle as the change-gears of an engine-lathe, thereby causing the cutting-spindle to make as many revolutions as there are teeth required in thy: wheel, while the main spindle makes one revolution.
The cutting-tool is composed of a series of cutters rigidly connected, which revolve, and at the same time move longitudinally. or endwise, at right angles to the axis of the wheel to be cut; and at the same speed, it is continually revolving, at the pitch-line, the motions being the same as in the case of a rack engaging with a revolving gear.
As it would be impracticable to continue moving the whole series of cutters endwise, they are bisected, and these segments are connected in series forming two sections, which revolve upon a C3111111011 axis, and each section is given an independent endwise motion by means of a cam. When one section is engaged in cutting, it is carried endwise in the same direction and at the same velocity that the pitch-line of the wheel is revolving, until disengaged from it, when the emitters, while continuing to revolve, are carried back by the cam to their original position, ready for the next tooth. By means of both sections, as they continually revolve and alternately slide forward while cutting. and hack when disengaged, there is a continnons cutting and generating process of the teeth in the revolving wheel. The head carrying the cutters is automatically fed across the face of the wheel, and when the cutters have proceeded once across the gear is completed.
Fig. 7 is a side elevation of a bisected cutter ; and Fig. 8 shows a series of six cutters, the end one being in elevation and the others in cross-section—these having cutting portions, which in cross-section represent the teeth of a rack, with the addition to the diameter of a given proportion of the 'deli by which the clearance and fillets at the bottom of the teeth are made. If their cutting portions are formed of cycloids, then the whole set of gear-wheels cut with them will be of the cpicycloida] or double-curve system. if they are formed simply of straight sides, then a set of involute or single-enrve gears will be generated and cut, or their cutting portions may be composed of both straight lines and cycloids and produce Prof.
McCord's recent system of gearing, which has composite teeth with the contours partly invo lute and partly epicycloidal.
All the cutters in a series are made exactly alike and interchang,cable, the thickness of each or the distance from the center of one to the center of that adjoining being equal to the pitch of the gear to be cut. As indicated in Fig. 7, the two segments of a cutter are first made whole, with four holes an equal distance front the center, through which the rods pass that fasten them together. After the cutters are nearly completed they are bisected with a narrow tool, leaving two holes in each segment.
Fig. 9 is a cross-section of the head, showing the mechanism for revolving and reeiproent ing the cutters, The rods which extend through the cutters serve not only to hold them firmly together but to revolve them. and at the same lime a, t as slides for the reviprocating motion. The spindles on either side of the cutters, through oini1] the rods extend. are revolved independ ently and at the same speed by means of a parallel shaft, having a pinion at each end, which with a large gear on each dle. By this wails the four rods carrying the two cutter are revolved front each 1.1111, thus avoiding the torsional strain ‘Villeh if driven from one end only. The pair of rods for each section. after passing through one of the spindles, terminates Fr0111 each of these blocks a stud ex on which is jonimaled a roll, engaging with a cam attached rigidly to the head. This can is shown in Pig. 19, the working portion, being made in tin form of a sercw-thread, which, if ex tended all the way around, would have a lead equal to the thickness or pitch of tile ,•ntli.r. As each section of the enllisrs 1'11;Z:1.'0S with thy lint three fourths of a revolution, the thread portion of the can which carries the cutters forward extends only three fourths of its eiremriference, leaving the ni her one fourth for the ri'VVI'S(` VIII*VOS Of the CHM t I) bring the cutters back to their starting-point. Provision is made for adjusting one section of the cut.
• tern so as exactly to coincide with the other. The variation in the spacing from one tooth to another is reduced to a minimum, as the series of cutters act upon both sides of a number of teeth at the saute time, and serve to average and eliminate any local inaccuracies in the di vision of the index and driving-gears; also to obviate any tendency to crowd the wheel from one side to the other.
The endwise motion of the cutters and the revolving of the wheel at the pitch-line being exactly the same, the process of generating and cutting the teeth goes OD continuously and uniformly around its entire periphery, so that one part is not heated more than another, but all the teeth are cut under exactly the same conditions, and when the revolving cutters have once passed across the face all the teeth in the gear are completed and given the correct form for each diameter of wheel ; and as by the Willis theory all gears are eat to run into a rack, so by this process the Sang theory is put into practice and a rack is made to cut correctly all gears.
Gear-Cutter: see Watches and Clocks.
Gears: see Carriages and Wagons.
Gin, Cotton: see Cotton-Gin.
Glassing-Machine: see Leather-Working Machinery.