Patent GB-458194-A (GB)
Abstract: 458,194. Boring-bars, turning-tools, &c. JEARUM, F. C., Green Gate Cottage, Old Rectory Lane, Chipstead, Surrey. Aug. 17, 1935, Nos. 23149 and 31783. [Class 83 (iii)] [See also Group XXIII] In adjustable tool bits having super-hard tips of diamond or tungsten carbide for boring- bars, turning-tools, &c., a member carrying the hard tip is adjusted by definitely progressive adjusting means in a body which is adapted to be clamped in operative position in the boring, turning, &c. machine. In one form, the body comprises a cylindrical easing 1, Fig. 2, receiving the shank 4 of the head 2 which carries the diamond or hard metal tip 3. Axial adjustment of the shank is effected by a screw 5 engaging therein and secured by a keyed connection and screw 11 to a collar 7 which is rotatable on the casing 1 by means of a polygonal aperture 12. The collar is graduated on the periphery to indicate the setting and the shank 4 is splined to the casing by a spring plunger 15 engaging one of three slots 18. These slots allow the casing to be contracted to grip the shank when it is clamped in a tool-holder. In a modification, the shank 21, Fig. 4, is screwed into a graduated adjusting nut 22 which is pulled back against the casing 25 by a spring 26 acting on a screw 23 attached to the shank. In a further modification, a bolt 30, Fig. 6, has threads 30, 31 of the same hand but different pitch engaging the shank 29 and the casing 27 respectively so as to adjust the shank by the differential action of the two threads. The bolt is rotated by a flat finger 34 attached by a key and screw 39 to the graduated collar 38. In another differential construction the bolt 41, Fig. 7, has threads of different pitch engaging the shank 43 and a sleeve 42 secured to the graduated collar 47. A key 50 has portions 51, 52 engageable with the screw 41 and collar 47 respectively, the action being such that on inserting the key fully, the screw and sleeve rotate together to give a coarse adjustment to the shank, but on partly withdrawing the key the screw only is rotated to give a fine differential adjustment. A graduated collar 53 on the key, pressed by a spring 53<1> towards the collar 47, indicates the fine adjustments. In another modification, the bolt 64, Fig. 9, has differential threads engaging the shank 64<1> and sleeve 57, and the latter is rotatably attached to the graduated collar 85 by a spring ring. A spring finger 60 pressed out of the casing 59 engages a ball with a number of recesses 62 in the sleeve 57 and a flat finger 65 is permanently attached to the collar 85 as to engage the bolt 64. On inserting the key 67 fully, the bolt, sleeve, and collar rotate together for the coarse adjustment, but on engaging the key with the collar only, the bolt is rotated in the sleeve and shank for the fine adjustment. The graduations on the collar indicate both the coarse and fine adjustments in this construction. In a further modification, the shank 69, Fig. 11, is of rectangular section and slides in an open slot in the body 68. A lateral projection 72 at the rear end of the shank is pressed by a spring plunger 73 against a screw 77 rotatable in a lug 76 slidable in a recess in the body and engaged by an archimedean cam 79 rotatable on the body. The cam, which is graduated, is shaped to give the desired degree of fine adjustment, and a coarse adjustment may be obtained from the screw 77 and a scale 83 on the lug 76. Alternatively, the screw 77 may be dispensed with and the cam then engages the lug 72 directly.