GB527518A - Improvements in machines for testing the accuracy of face curves in gears, gear shaper cutters and other articles - Google Patents

Abstract

527,518. Gauging gear teeth &c. MILLER, E. W. April 13,1939, No. 11251. [Class 106 (ii)] Comprises a construction in which means are provided for producing a relative translation and rotation between a feeler device and the involute form to be tested, in which the relative translation motion takes place in a line tangent to the base circle of the involute form, a lever of variable effective length being provided to accord with different base circles. A spindle 21 has a tapered socket in the upper end to receive a centre 25 on which the gear to be tested is mounted. An arm 39 clamped to the spindle 21 carries a worm gear 40 by which it may be rotated from a handle 45. A feeler 48 engages the side of a tooth to be tested and gives a multiplied movement to an indicator 49. The feeler contact point is moved tangentially to the base circle of the gear by the following mechanism. The arm 39 carries a master tooth 50, the faces of which are accurately formed involutes of a large master base circle. A " drive " slide 51 mounted to move endwise in the base over the arm 39 carries abutments, 52 53 embracing the tooth 50 and forming the sides of the master rack teeth. A second " indicator " slide 54 carrying the feeler and indicator is mounted to travel parallel to the slide 51 and is connected to it by a ratio lever 55. Pins 59, 61 on the " drive " and " indicator " slides respectively project into slots 60, 62 in the lower and upper faces of the lever 55. Movement of the feeler is thus proportioned to the movement of the " drive " slide and equal to linear movement of the base circle of a gear mounted concentrically on the spindle and of which the base circle is a radius equal to the distance of the feeler from the axis of the spindle. The slot 62 permits of adjustment of feeler to gears of different diameter with corresponding change in the ratio of its measurement. The " indicator " slide is mounted in an adjusting carriage 63 which rests on the base and moves transversely to slides 51, 54. An opening 69 through which the spindle 21 passes permits the desired range of movement. Adjustment is by handwheel 73 and screw 70 assisted by a scale 75 and index microscope 74. Alternatively, gauge blocks 76 are placed between an abutment 77 on the base of a seat 78 on the carriage. When the spindle and gear are rotated the feeler point traces an involute curve. If the teeth faces are correct no movement of the indicator occurs. The slide 51 carries a scale 99 adjacent to the index 100 graduated in angular degrees of the master base circle. This aids in locating the errors. In a modification, the rack and gear couple transmission from the rotatable spindle to the drive slide is replaced by tapes. In a further modification, means are provided for imparting both linear and rotational components of motion to the drive slide and feeler.