Patent GB-384572-A (GB)
Title: Process and apparatus for accurately cutting and rectifying gears
IPC: B23F1/06
Filed: 1932-06-06
Abstract: 384,572. Gear-cutting. AMANN, P.E., 9, Rue du Sanglier, Nanterre, Seine, France. June 6, 1932, No. 15986. Convention date, June 6, 1931. [Class 83 (iii).] In a device for cutting gears from a templet of the tooth form the work is carried on a table which moves past a milling or grinding tool, the work being oscillated about an axis passing through the blank cone apex and through a point on the axis of symmetry of the templet which is maintained in continuous contact with a stationary plane surface passing through the blank cone apex and containing a generator of the operative surface of the tool. In the application to a horizontal-spindle milling- machine having a spindle 1 and fitted with the usual transverse slide 3, carrying a longitudinal slide 4, the slide 4 is fitted with curved brackets 5, 6 carrying on ball bearings curved plates 8, 9 which are concentric with a centre O, but may be of different radii. The plates carry sleeves 10, 11 on which is pivoted an oscillating frame 12 which may be moved by a hand-lever 13. The tool 26 has a plane operative face and a support 27 fixed to the machine head carries a spindle 29 provided with a pair of flat plates 31, 32, whose operative faces a, b, c and d, e, f respectively lie in the same plane, this plane containing the operative face of the tool and the vertical axis x, y, passing through the imaginary cone apex O. Either face may be brought into operative position by rotating the spindle 29 through 180‹. A spring 23 is arranged to be in its unstretched position when the axis 10, 11 lies in the plane of the plates 31, 32, so that in operation the spring is either in tension or compression and always tends to engage the templet 20 with the plate 31 or 32. The templet is mounted in the frame 12 on a support 21 and the workpiece such as a model bevel gear tooth is mounted between brackets 12a, 12b. In operation, for shaping one side of the tooth the frame 12 is rocked to move the templet over the stationary face 31 while the table 4 is reciprocated by the usual gearing. Rocking of the frame around the axis 10, 11 also causes movement round the axis x, y and profiles similar to the profile p, k, q of the templet will be cut along the workpiece which will have the correct taper towards the centre O. For shaping the opposite profile of the work, the plate 32 is brought into position and the templet is moved so that its opposite edge r, s engages the plate 32 thus compressing the spring 23. The tool is readjusted so that its opposite face which is now operative, lies in the plane of the plate 32. Preferably the axis 10, 11 intersects the axis of symmetry of the templet at the mid point m of the base of the templet. In the application to the cutting of a straight bevel gear, Fig. 2, the work is mounted with its axis inclined at half the root cone angle to the horizontal plane containing the axis 10, 11 and is fitted with a dividing- head so that the teeth are first cut in succession on one set of flanks after which the opposite flanks are cut. In place of a templet of a tooth, the templet of a tooth space, Fig. 9, may be employed. The milling-cutter may be replaced by a grinding-wheel for rectifying the teeth. The invention may also be adapted to the cutting of spiral bevel gears, the blank being rotated during the longitudinal movement of the work table to obtain the required spiral eagle. In order to maintain a constant inclination of the spiral of the teeth, the table feed is progressively decreased as the cutting zone passes from the large to the small end of the blank. The supports 5, 6, Fig. 3, are formed on a supporting base 37 slidable on the table 4. A bracket 39 extending from the carriage 3 carries a fixed arm 41 and a pivoted lever arm 43 which supports a slide 44 carrying a slotted plate 47. The slot in the plate 47 is engaged by a finger on the arm 41 and the dimensions of the slot are modified according to the spiral to be produced. The lever 43 is moved angularly by means of a stud 45 on the table 4 and the required variable movement is imparted to the base 37 through a link 49. The traversing screw of the carriage 4 is connected through a gear train 57 and telescopic shaft 59 to the dividing-head 53 to impart the required rotation to the blank. The plates 8, 9 may be connected by linkage, Fig. 4, to increase the rigidity of the mechanism. Either plane or conical milling- cutters may be employed but in all cases the operative generatrix of the tool surface is vertically arranged. The oscillating movement of the work support may be actuated automatically from the longitudinal table movement.