From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Brochure for the Fellows Gear Lapping Machine, 3-Lap Recess Type.
| Identifier | ExFiles\Box 155\3\ scan0007 | |
| Date | 1st January 1932 | |
| SOLE SELLING AGENTS ALFRED HERBERT LTD. Fellows Gear Lapping Machine (3-LAP RECESS TYPE) THE FELLOWS GEAR SHAPER COMPANY has developed a practical method of finishing gears by lapping after hardening. This process in addition to smoothing the contacting profiles of the teeth, also removes slight distortions resulting from heat treatment, thus producing more accurate, efficient, longer lived and quieter operating gears. Extensive tests have conclusively demonstrated that, with all other factors remaining constant, the smoother the finish on the teeth, the nearer the approach to silence in operation, either under load or running idle. It is also a demonstrated fact that smoothness of contacting profiles has a direct effect on increased gear life. Of the various refining processes employed after heat treatment, lapping, if properly conducted, presents the most satisfactory and economical method so far devised. On helical gears the improvement made possible by lapping is particularly noticeable. The economy of the process lies in the fact that, in the majority of cases, the gears can be lapped in a few minutes. Furthermore, as this machine is automatic in operation, each gear is lapped for a definite period so that consistent results are not dependent on the skill of the operator. In practice all gears of the same size, pitch, etc., receive the same amount of lapping; they are then tested on speeders for quietness and bearing, and those which do not pass inspection are set aside and relapped. In this way gears can be lapped on a production basis at a comparatively low unit cost. The outstanding features of this machine, which is known as the “3-Lap Recess Type,” are: Rapidity of lapping, correction of tooth shape and helix angle of helical gears, and the production of smoothly finished tooth profiles on a high production basis. This machine is adapted to the lapping of external spur, helical and herringbone gears, and is particularly suited to the lapping of shoulder gears and gears having a recess or groove at the end of the teeth. Principle of Operation The principle employed differs from that of rotating mating gears with lapping compound introduced between the teeth. This machine, a front view of which appears in Fig. 1, does not depend simply upon the rotation of the work and laps to effect the lapping action. It affords in addition a reciprocating movement of the work at a fairly high rate of speed. This effects an adequate distribution of the lapping compound over the contacting teeth, and results in more efficient and rapid lapping action. FIG. 1. Front View of 3-Lap Recess Type Gear Lapping Machine Adapted to the Lapping of Spur, Helical and Herringbone Gears FIG. 2. Close View of Work and Laps, also Support used when Lapping Shank or Stem Gears The latter operation, obviously, is in the nature of salvage and cannot be conducted on a production basis. Electrically-Controlled Timing Mechanism Reversal of direction of rotation of work and laps, as well as the number of revolutions in each direction, is accomplished electrically through the medium of reversing and limit switches. The machine is therefore automatic in operation, and the number of revolutions in each direction can be changed by withdrawing and rotating knob Q on the limit switch shown in Fig. 5. The limit switch can be set to any one of eight pre-determined number of work revolutions, upon the completion of which the machine stops automatically. This machine is designed for individual motor drive. A 2 H.P. constant-speed reversing type motor, 1200 R.P.M., mounted in the base, drives the machine through a single pulley, and operates both the rotary and reciprocating mechanisms; also the lubricating pump and electric limit switch. A ½ H.P. constant-speed motor, 1800 R.P.M., mounted in the opposite side of the base, drives the abrasive compound pump. This pump is provided with an agitator to keep the compound mixed when the machine is in operation. It is advisable to operate this pump before the machine is started to thoroughly mix the lapping compound. In order to regulate the amount of compound pumped to the work, a by-pass is inserted in the line, so that the pump can work at full capacity, but the flow of compound on the work is restricted. Laps, Lapping Compounds, etc. Laps for use on this machine should be made from a good grade of cast iron. Lapping speeds should not exceed 200 surface feet per minute. Number of strokes and stroke length are governed by the gear being lapped. Grain of abrasive should be in the vicinity of No. 320 to No. 400, depending upon amount of lapping necessary to correct errors and finish desired. Oil used should retain abrasive in suspension to obtain best results. The work is then lapped for a predetermined time, and gears which do not “clean-up” are set aside and re-lapped until the desired corrections have been effected. FIG. 7. Dial Indicating Gages for Controlling Setting of Axial Alignment of Two Upper Lap Spindles Specifications of Gear Lapping Machine (3-LAP RECESS TYPE) Capacity: Maximum pitch diameter of work . . . . . . . . . . . 7 inches Minimum pitch diameter of work . . . . . . . . . . . 2 inches Maximum diametral pitch . . . . . . . . . . . . . . . . 6 inches Maximum face width . . . . . . . . . . . . . . . . . . . . 1 1/4 inches Weights: Of machine without motors and electrical equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2650 pounds Of machine crated for domestic shipment not including motors and electrical equipment . . . . . . . . . . . . 2930 pounds Of machine boxed for foreign shipment not including motors and electrical equipment . . . . . . . . . . *3200 pounds Maximum overall length of machine . . . . . . . . . . . . . 4' 1 inch Maximum height of machine . . . . . . . . . . . . . . . . . . 4' 10½ inches Maximum width of machine . . . . . . . . . . . . . . . . . . . 2' 5¾ inches Dimensions of crate for domestic shipment: 4' 9¼" x 3' 5¾" x 5' 3" high Dimensions of box for foreign shipment: 4' 9¼" x 3' 5¾" x 5' 3" high *2 H.P. A.C. Motor weighs approximately 100 pounds. ½ H.P. A.C. Motor weighs approximately 50 pounds. MANUFACTURED BY THE FELLOWS GEAR SHAPER COMPANY SPRINGFIELD, VERMONT, U. S. A.{Mr Adams} Printed in U.S. A.{Mr Adams}, 1932 | ||