Patent GB-385600-A (GB)
Title: Improvements relating to methods of and apparatus for cutting grooves, recesses and the like
IPC: B23G9/00
Filed: 1931-03-25
Abstract: 385,600. Turning; boring. GARRARD, C. G., Thorngreen, Thorn, near Dunstable, Bedfordshire, and EVERTITE LOCKNUTS, Ltd., 95A, Chancery Lane, London. March 25, 1931, No. 9165. [Classes 83 (ii) and 83 (iii).] Making nuts boring heads.-In a method of and apparatus for forming annular grooves in internal bores, such as in the production of lock-nuts, a single pointed tool with side clearance is fed radially into the side of the bore and is simultaneously given a rapid vibrating motion in the direction of the axis of the bore and within the required confines of the groove. In the production of V-section grooves, a cutter a, Fig. 1, of smaller angle and width than the groove to be formed, is rapidly vibrated axially through progressively smaller distances whilst being fed radially into the work so as to follow a path such as that shown at x. For producing a V-groove having an included angle of 45‹ a cutter having an angle of 30‹ may be used and the radius at the end of the cutter corresponds with that required at the bottom of the groove. Either the work or the tool rotates about the axis of the bore during cutting. With rotating work, the toolholder comprises a block c, Fig. 2, secured by a shank c<1> in a machine such as a nut tappng machine. A second block d is slidable along inclined guides c<3> on the block c, a spring e located in recesses in the two blocks serving to maintain a bracket r<2> on the block d in contact with the side of the block c, in which position a plunger g carrying the cutter a is co-axial with the shank c<1>. Lock nuts r<4> secured to the block c limit movement of the block d in the opposite direction. The plunger g is reciprocated within the block d by means of a crank pin p rotated by a pulley h<2> and engaging a slider p<1> located in a slot q of a lever j pivoted at j<1> in a member k which is adjustably secured in the block d by a screw l. A second slider p<3> located in the slot q engages a pin p<2> on the plunger to reciprocate the latter from the lever, the slot q and pivot j<1> being arranged on opposite sides of the lever so that the axis of the pin p<2> may be made to coincide, in one position, with that of the pivot. In operation, the position of the pivot j<1> is adjusted by the screw l to give the amplitude of vibration of the cutter required for the base of the groove to be formed, and the nuts r4 are adjusted to allow the tool to penetrate to the required radial depth. The tool-holder is then fed up to the rotating work until a fixed stop f arrests the block d whereupon further feed of the block c causes the cutter to be fed laterally into the work, the amplitude of vibration of the cutter being progressively decreased as the axis of the pin p<2> and pivot j<1> approach each other and ceasing when these axes coincide, at which point the bracket r<2> meets the nuts r<4> and stops the lateral feed of the cutter. This form of the device may also be used with stationary work by rotating the device as a whole, the crank drive being correspondingly modified. In another form, for use with stationary work, the block d, Fig. 4, is housed within a shell c and is guided in an inclined direction by means of pins r. The coaxial position of the block d with respect to the shank c<1> is determined by a stop r<5> on the shell and lateral motion of the block in the other direction is limited by an adjustable screw r<1>. The block d is normally pressed into co-axial position by a spring plunger e engaging a part k<1> attached to the block and adjustable along a surface d<3> parallel to the pins r by means of a screw l<1>. The plunger g carrying the cutter a is reciprocated within the block d by means of a strut g<2> slidable through the part k<1> perpendicularly to the surface d<3> and acted upon by the inclined end s<1> of a spindle s which is rotated by bevel gearing t<1> from a pulley t<2> co-axial with the shank c<1>. Inclined spring plungers in the block d engage a shoulder e<3> on the plunger g to maintain the strut in contact with the cam surface s<1>. In operation, the part k<1> is adjusted so that the distance between the axes z<1>, y<1> of the strut g<2> and spindle s respectively will give the required commencing amplitude of vibration to the cutter and the rotating shank c<1> is then fed towards the work v. When a hollow stop d2 attached to the block d encounters the upper edge of the work further axial motion of the block and cutter is arrested and continued axial feed of the shank causes the cutter to be fed laterally into the work, the vibrations of the cutter decreasing progressively to zero as the axes y<1>, z<1> approach each other. Grooves of other than V-section such as square or dovetailed section may be produced by varying the relative positions of the pivot of the lever j in Fig. 2, the crank shaft centre and the tool plunger axis or the corresponding parts in Fig. 4. Either form of the device may be used in a machine specially designed for the purpose, which may also perform other operations on the work.