Patent GB-570179-A (GB)
Title: A method of and machine for generating variable-width grooves in the teeth of gear cutters
IPC: B24B3/34
Filed: 1943-05-24
Abstract: 570,179. Grinding gear cutters. TRIGGS, W. W. (Follows Gear Shaper Co.). May 24, 1943, No. 8259. [Class 60] Flat top cutters employed for planing gears, of the type having grooves made in one end of the teeth contiguous to the cutting edge to provide top rake throughout the edge, have the grooves formed with continually increasing width from the tip to the root of the teeth to provide clearance for escape of chips. Fig. 8 shows a helical cutter in end view with teeth t, t<1>, and Fig. 11 shows a sectional view of one of the teeth ; the groove is shown at g, and is formed along the edge of the tooth adjacent to the side face s which makes an obtuse angle with the end face. During operation, the cutter is rolled to carry the tooth edge over a grinding- wheel G acting as the grooving-tool, and at the same time the wheel G is moved axially, approximately normally to the cutting edge of the tooth, so as to produce the varying width of the groove ; the acute edge of the tooth is ground to give a cutting edge with a top rake surface h A machine for effecting the grooving comprises a spindle 11, to which the cutter is clamped, rotatably mounted in a rocking holder mounted in a carriage 12 and provided .with a head 13 and collar 14 to which is secured a bridge 18 having a handle 19 ; a rod 20 to enter between any two teeth of the cutter is carried by the bridge 18. The carriage slides on a base 15 carried by a pedestal 16, and carries a rack 22 meshing with a suitable gear segment 21 on the spindle holder, so that angular movement of the bridge by handle 19 causes bodily movement of the carriage 12, thereby rolling the cutter. The grinding-wheel G is carried on a shaft 23 rotatable in a housing 24, the spindle bearing being a sleeve 25 slidable endwise in a bushing 26 fixed in the housing, a spring 59 serving to press the bushing 26 in one axial direction. The shaft 23 is driven through belt gearing 28, 29, 30, including a long pulley 28 driven by an electric motor 27 supported, as shown in Fig. 3, to tension the belt. The housing 24 is carried by a bracket 31 adjustable on pedestal 16, and may be adjusted angularly to suit right- or left-handed helices on the cutter, about a pivot 34. The sleeve 25 is given endwise movement, to move the grinding-wheel to widen the groove in the cutter, by a pinion 39 engaging rack teeth 40 in the sleeve and carried by a shaft 36 mounted in the housing 24 and secured by clamp 42 to one end of an arm 41. The arm has at its free end a slot 43 engaging a sleeve 48 adjustably secured in a transverse slot 45 in a block 44 secured to the carriage 12 ; the block is mounted to be longitudinally adjustable on the carriage by means of screws 52, passing through slots 53 in the block to engage a series of holes 54 in the carriage, and an adjusting screw 55. A duplicate pinion 61 and shaft 62 serve for treating cutter of opposite helix ; by adjustment of the sleeve 48 and block 44, the required axial movements are given to the grinding- wheel, timed with the rolling movement of the cutter. A dust guard 64 is mounted to cover the pin-and-slot connection 48, 43, a dust guard 65 is secured to bushing 26 and a dust cover 66 is secured to the outer end of the housing 24. The rolling movements may be given to the grinding-wheel instead of to the cutter.