Patent GB-466293-A (GB)
Title: Improvements in means for adjusting tools in boring bars
IPC: B23B29/034
Filed: 1936-01-13
Abstract: 466,293. Boring-bars. JEARUM, F. C. Jan. 13, 1936, No. 1095. [Class 83 (iii)] A boring-bar having progressive means for adjusting the cutter-bit in either direction of adjustment has a rotatable threaded worm or screw member in a pocket of the bar or body to adjust the cutter and a direct coupling between the worm and a graduated dial which indicates its rotation. In one form the boring- bar 1, Fig. 2, is provided with intersecting holes 2, 3 for receiving the adjusting worm 5 and cutter 11 respectively. The worm is held axially by a screw 10 engaging its reduced end 6 and is provided with a screw thread 4 engaging a threaded segment 12 on the cutter. The worm is rotatable by means of a polygonal socket 7 therein and a scale on the bevelled surface 8 thereon reads against an indicator on the bar at 9. A clamping pad and screw 15 engages a flat 16 on the cutter to force it against the side of the hole 3 without reacting on the worm 5. In another form the worm 22, Fig. 3, engages a segmental thread 23 on a member 26 located in a hole 20 intersecting the holes 18, 19 and carrying teeth 261 engaging teeth on the cutter 25. The worm is rotated by a stem 30 keyed thereto at 30<1> and secured by a screw 32, axial motion of the worm being prevented by a sleeve 28 screwed in the boring-bar 17. The member 26 may be rotated about its axis to disengage the teeth 26<1>, whereupon the cutter 25 may be withdrawn after loosening the clamp 34. In a modification of this form the cutter 37, Fig. 4, may be surrounded by a sleeve 38 located between a shoulder 40 and a screw 41 and having a flat on one side to engage the member 36 which has threaded engagement with the worm 35, the latter in this form being conical to allow the cutter to be inclined to the axis of the boring-bar 35<1>. In other forms, a parallel or tapered worm engages directly with a screwed segment on the sleeve 38 and where such a sleeve is employed the cutter may be rotated about its axis to vary the side rake of the cutting edge. A vernier may be provided on the flange of the sleeve 28 reading against a scale of 50 divisions on the worm, which, with a thread pitch of 20 to the inch, gives adjustments of the cutter in ten-thousandths of an inch. In a further modification the sleeve 52, Fig. 6, has a slot to receive a block 54 engaging through serrations with a plunger 53, and held in engagement by the stem of the cutter 51. On removing the cutter, the block 54 may be disengaged from the plunger 53 to allow withdrawal of the sleeve 52. The worm 57 has a screwed portion engaging a screwed segment 56 on the plunger and also a second screwed portion 58 of similar hand but different pitch engaging an internal thread in a nut 59 secured by screwing in a sleeve 60, so as to adjust the cutter by the differential action of the threads. The worm 57 is slidably keyed to a central flat-sectioned spindle 62 formed of two parts held together by a screw 67 which also holds the graduated flanges 63, 65 against axial movement. The worm is rotated by polygonal holes 68 in the flanges 63, 65. Frictionally held loose dials 69, 70 may provide a movable zero for reading with the scales on flanges 63, 65. In another form a cylindrical worm diametrically arranged in the boring-bar engages a toothed wheel which meshes with a rack on the cutter, the latter then being directed at an angle to the axis of the bar or parallel to this axis. In a further modification the worm 90, Fig. 11, is formed as a conical involute spiral engaging teeth on the inclined cutter 91 and has axial dogs 102 meshing with a graduated sleeve 101 rotatable by means of a key 106. Two thrust pads 95 engage flats on the worm and are slotted to engage a collar 99 on a screwed sleeve 100 which clamps the worm axially to the graduated sleeve 101. The cutter is clamped in position by a bar 94 actuated by a nut 96, the thrust being transmitted to the bar 93 through the pads 95 and a vernier sleeve 103 screwed into the bar. In another modification for use in boring large diameters a cylindrical housing is mounted on the bar and the cutter is adjusted radially by a flat spiral on the end of a rotatable disc in the housing.