Patent GB-305831-A (GB)
Title: Improvements in grinding or abrading machines
IPC: B24B5/06
Filed: 1928-02-21
Abstract: 305,831. Marks, E. C. R., (Greenfield Tap & Die Corporation). Feb. 21, 1928. Round holes, enlarging and trueing; trueing rotating tools; gauges; spindles and spindle mountings.-In an internal grinding-machine the work K is carried on the front end of a hollow work-spindle 16 while the grinding-wheel W is inserted into the work from the rear of the spindle, a trueing device T for the grinding-wheel and a device S for gauging the work being also mounted to extend into the work-spindle from the end opposite to that at which the work is secured. The spindle is carried in a ball bearing 17 in a head 18 mounted on the work table 11 which slides in guides 12, 13. The front of the spindle is flanged and provided with rings 90 engaging grooves 91 in a ring 92 secured to the head, this arrangement serving to exclude abrasive &c. from the spindle bearing. The guideway 13 has its front and rear walls disposed at unequal angles to the vertical, the former being substantially 45‹ and the latter at about 25‹ to the vertical. By this construction, the line of pressure of the tool against the work is acutely inclined to the rear face of the guideway 13, thus forcing the table down firmly on to its bed. The front guide surface 12 is flat to permit expansion or contraction of the table. The work-spindle carries a driving-pulley 23 driven from an electric motor M through belt gearing 35, shaft 33, spur gearing 32, belt 28, countershaft 26 and belt 24. A clutch is provided in this train so that the work spindle may be stopped independently of other rotating parts. The grinding-spindle 40 which is mounted in a head 42 slidable transversely on ways 43, 44 on a support 45, is also driven from the motor shaft 37 through a belt 51, countershaft 49, and belt pulley 46. The cross-feed of the grinding-head 42 is effected through gearing from a hand-wheel 56 or, alternatively, an automatic cross feed may be employed. The table 11 is preferably reciprocated longitudinally by hydraulic mechanism, the main valve of which may be operated manually from a handle 63. This control handle is also connected to a valve rod 65 to vary the rate of table traverse. Auxiliary valves may be operated by adjustable dogs 68, 69 on the table to control the extent of the movement. The gauging device comprises a cross slide 70 sliding in ways on the work head and adjustable through-rack-and pinion gearing from a knob 79. An arm 82 extends into the work-spindle from one'end of the slide 70 and carries a cross bar 83 to which the contact lever 85 is pivoted by means of flat springs 86. The contact diamond or steel point 86<a> is mounted on the short arm of the lever while the long arm 85<a> engages through a plunger rod 87 with the plunger 88 of a visible indicator 89. The gauge may be adjusted by moving the slide 70 so that a zero reading is obtained when a work-piece of standard size is in position. The slide 70 is then clamped and successive work-pieces will be ground to size when the gauge indicates the zero. The trueing device is similarly mounted on a cross-slide 93 adjustable from the head 99 and having an arm carrying the dressing tool or diamond point 103. Additional clamping screws are provided for locking the slides 70 and 93.