GB484125A - An improved feed-mechanism for portable boring bars and like tools - Google Patents

Abstract

484,125. Portable boring-bar machines. TAYLOR, H. G., and WILLIAMSON, J. V. Nov. 20, 1936, Nos. 31855/36 and 1137/37. [Classes 83 (i) and 83 (iii)] In a portable boring-bar or like tool, a bracket is secured to the bar at an axially adjustable point so as to have free rotative engagement therewith and a nut on a feed screw which is axially secured parallel to the bar engages the bracket to feed the bar axially. The machine comprises a number of brackets 16 adapted to be adjustably secured to a crank-case 10 and provided with sockets 17 in which rods 18 may be clamped. The rods 18 are rotatably and axially adjustable in the sockets and carry bearings 19 for the boring-bar 12. Cutters 14 are secured in transverse bores in the bar by screws 15. A feed screw 25 is fixed by a bracket 27 to one of the brackets 16 and has a nut 26 rotatable thereon, the nut being axially immovable between the limbs of a U-shaped member 20 having bosses 21 freely slidable on the bar 12 and engaging a collar 23 adjustably secured to the bar. As the bar is rotated bv means of a handle 33 thereon a tooth 32 on the collar 23 engages once in each revolution with a gear 30 on the nut to feed the bracket 20 and the bar, or the nut may be rotated for adjustment of the bar by means of a knurled flange 29 thereon when the tooth 32 has been moved along its slotted support 31 to an inoperative position. A spring clip 34 restricts the free rotation of the nut. In use, collars are fitted to two or more of the bearing housings 11 in the crank-case 10 and the bar 12 inserted therein so as to be positioned before the brackets 16 and rods 18 are secured. The collars are then replaced by the bearings to be bored and the cutters inserted in the bar. In an alternative form of the supports 18 hollow rods 45, Fig. 5, are adjustable in the sockets 17 and are provided with cylindrical or V-shaped surfaces 46 engaging cylindrical surfaces 50 on bearings 47 for the bar 12. Each bearing has a pivot 52 concentric with the surface 50 which serves to clamp the bearing in any adjusted position by means of a rod 53 attached thereto and a nut 55. A spring 56 holds the bearing loosely when the nut is released and the bearing may be split at 48 and tightened on the boring-bar by a nut 49. Casting ; turning.-In order to adapt the boring-bar readily to bearing housings 11 of different size, the collars fitted to the housings may be formed by casting white-metal 39 in a mold consisting of a base 35, Fig. 9, having concentric annular grooves 36, in any one of which is placed a tube 37 of appropriate size. The collar is cast between the tube 37 and a central spigot 38 having the same diameter as the boring-bar, and a hole 40 in the base produces a pin 44, Fig. 7, on the collar by which it may be rotated through a pin 43 on the bar in order to turn it to exact size by means of a turning tool 42 on a frame 41 attached to the crank-case 10.