Patent GB-112879-A (GB)
Title: New or Improved Construction of Twist Drill Grooving and Clearance Grinding (or Milling) Machine.
Inventor: HUNT HERBERT
IPC: B23C3/32
Filed: 1917-05-07
Abstract: 112,879. Hunt. H., Hunt. H. W., and Hunt, P., (trading as Hunt & Sons, H.). May 7, 1917. Twist drills, sharpening; cutting-edges, shaping and treating.-A combined twist-drill grooving and clearance-making machine comprises two heads b, c upon one bed a, one h for milling or grinding grooves, and one c for grinding or milling clearances. Means for re-setting the work in transferring it from one head to the other are avoided. The width and depth of the groove are simultaneously and automatically varied as the grooving proceeds. A micrometer gauge nut is provided for regulating the depth of the groove. Means are provided for varying the pitch in both heads, for adjusting the work to do one groove and then another, and for automatically stopping the grooving at the end of the groove. Self-adjusting ball bearings support the clearance-forming tool. The grooving headstock 1. Fig. 3, carries a belt-driven spindle 2 with tool 3 and driving gear-wheels 4 for rotating a shaft 9 actuating parts of the head b, which carries a swinging bracket 11, Fig. 4, journaled about a vertical spindle 12 in bearings 1<a>, 1<b>. The bracket 11 lies normally at 60 degrees to the drill spindle and carries a rectangular guide and rest 13 for a carriage 14 actuated by a nut 15 secured thereto and engaging a traversing-screw 16 The carriage 14 has a loose rotary spindle, which carries the drill-blank chuck and is driven by a key 22 engaging a key-way on a. spindle 21 carrying a loose gear wheel 25 driven through change gear from the traversing-spindle. The wheel 25 has two or more holes, which engage an adjustable spring detent 30 carried by the spindle, one for each drill groove. The shaft 9, Fig. 7, actuates screw 16 through universal joints, a worm 32 and a wheel 31. The worm 32 is carried by a lever bracket 35 pivoted to the frame 11 and carrying a half-pin 39. which normally engages a half-pin 38 in a lever handle 37. The worm 32 may be lowered by hand or a travelling stop 59 engaging the lever 37. The spindle 12 carries a work-holding sleeve 43 and a micrometer-nut 49 and lock-nut 50 for regulating work, and is supported by an eccentric 52 actuated by a lever 53 connected to an adjustable hook 56 on the carriage 14. When the carriage is moving forwards, it exerts a pull on a chain 54 and lowers the spindle 12 to produce a gradual variation in the depth of the groove. At the same time, the bracket 11 is swung by a link 57, Fig. 2, connected to the saddle 14 to widen the groove from the drill point to the shank. The work is lowered on moving the lever 53 to the right, and the worm 32 is also lowered to facilitate the return of the saddle to starting point. The head for grinding the clearances on the drill carries a spindle 60, Fig. 7, a grinding wheel 62 and a pulley 61 driven by belt gearing from a pulley 64. The spindle 62 is supported by ball-bearings 91, 92 93. A spring is arranged between the bearings 91, 92 to take up the wear. A forwardly-extending vertical bracket 69 carries an arm 69<a> supporting a rotary drill-carrying spindle 70 in bearings 69<b>, 69<c>. The bearing 69<b> carries a flanged liner 71 encircled by a retaining-ring 71b, which holds it in one of two positions for grinding the two grooves. An interchangeable and internally screwthreaded sleeve 73 is mounted in and secured to the liner 71 and engages a hollow threaded sleeve surrounding and clamped to the spindle 70 between a shoulder thereon and a hand-wheel 77. The pitch of the thread corresponds to that of the groove in the drill. The nut 77<a> may be released and the spindle 70 adjusted to vary the width of the ground part. The bracket beneath the grinding-wheel carries an adjustable grooved work-support 78. The bracket 69 is raised or lowered by hand-actuated tooth gearing actuating a screw 79. The hand-wheel 84 is provided with a micrometer gauge, and adjustable and fixed stops 85, 86 limit the rise. The twist-drill blank, after being grooved, is transferred in its chuck to the grinding- head, the chuck holders of the two heads being identical. The wheel may have a pivoted guard, and a swivel lever carrying a diamond point may be provided for trueing it up. Telescope covers 89, 89a enclose the spindle 70. The chuck, Figs. 9 and 10, has a rounded stem 20<a> and two segmental flanges 20<b>, 20<c>, which engage recesses on the spindles 17 or 70, Fig. 7, to ensure alinement. The union 19 which clamps the flanges to the spindle has segmental gaps 19<a>, 19<b>, through which the flanges can be withdrawn on rotating it. A pin 20d limits the motion and ensures alinement of the gaps and flanges.