Patent GB-674067-A (GB)
Title: Improvements in centreless grinding machines
IPC: B24B5/18
Filed: 1949-04-27
Abstract: 674,067. Grinding. MICROREX SOC. ANON. April 27, 1949 [April 30, 1948], No. 11205/49. Class 60. A centreless grinding machine has the carriages 4, 6 of the grinding and control wheels 5, 7 movable over parallel slideways 2, 3 which are raised above the lower edges of the wheels, each wheel being mounted between the slideways on a spindle held at each end in a transverse bore in the corresponding carriage. The grinding wheel 5 is clamped by bolts 9, Fig. 4, between side plates 8, 8<SP>1</SP> which are mounted on a hub 10 by keys 11 and nuts 12. Tapered sockets 13, 13<SP>1</SP> in the ends of the hub are respectively engaged by the tapered ends of two spindles 14, 15, each of which is mounted by ball bearings in a bore in the carriage 4. The spindle 15 is keyed to the hub 10 by a pin 20, and a central bolt 21 passing axially through the spindle 14 and hub 10 is screwed into the end of the spindle 15. The drive of this wheel is from a motor 120, Fig. 2, through belts 121 passing over a pulley 19 on the spindle 15, and these belts are tensioned by a pulley 123 mounted on a pair of pivoted and weighted levers 124. The movement of the carriage 4 to and from the control wheel is effected by a screwed shaft 96, Fig. 19, mounted beneath the carriage and engaged by a nut 94 in the form of a worm wheel meshing with a worm 93<SP>1</SP> on a hand-operated shaft 93. The control wheel 7 which is of hyperboidal shape, is secured similarly to the wheel 5 on two spindles which are mounted by taper roller bearings 23, Fig. 5, in casings 24' set in bearings 25 in a semi-circular cradle 26; slots 27 in the cradle permit its being bolted to a vertical face of the carriage 6 at any desired angle. The wheel 7 is driven from a motor 54, Fig. 2, through change-speed gearing 55 presenting a range of speed variations, and two-speed gearing 57, and thence by a chain 66 to a toothed gear 67 on the drive spindle of the wheel; the chain is tensioned by a spring 72 acting upon a pivoted arm carrying a toothed wheel 69. The carriage 6 is movable to and from the wheel 5 by a hand-wheel 32, Figs. 2 and 9, which actuates a nut 31 engaging a screw 33 connected to the carriage; the nut 31 has a sleeve portion 30 embracing the cranked portion 29' of a shaft 29 journalled in the main frame 1 for operation by a handle. By this means, the hand-wheel permits initial adjustment of the carriage, and the shaft is subsequently rotated for effecting plunge cuts. To provide for the ejection of the workpieces in the latter operation, the shaft 29 has an extension 36, Fig. 8, having a peripheral spiral groove co-operating with a pin 37 on a shaft 39 journalled in the frame. This shaft is coupled with a further shaft 42, Fig. 17, on which is keyed a ratchet 45 adapted to drive, through a pawl 46, a lever 47 rotatable on the shaft. When the shaft 29 is rotated for a plunge cut, the lever 47 is swung clockwise against springs 48 until, at the end of the operation, the pawl strikes a stop 53 so as to release the lever for action against a pawl 49 on a piston 50 carrying an ejector rod 51. The work is supported for through-feed by a pair of supports, each consisting of two members 80, 80', Fig. 14, hooked over a lower hinge pin and adjustable to and from each other by nuts 83 acting upon pivoted bolts 84; dovetail plates 82 clamped in the upper ends of the members 80, 80' engage the work. A work-support blade 87, on which the workpieces slide during operation, is disposed in a slot in a base member 44 for vertical movement under the control of cams on a hand-operated horizontal shaft. The frame 1 contains a supply of water which is passed through a pipe 138, Fig. 2, to the wheel 5. To permit withdrawal of either of the wheels, a support 127, Fig. 33, is hooked on to the frame 1 for the reception of a tube 129 carrying an overhanging portion 130 supporting a winding drum and pulley 131 whereby tapered members 135 in a shackle 134 may be engaged with the side plates of the wheel and then lifted by a cable 133. Trueing.-The control wheel 7 is trued by a diamond carried from a spindle 114, Fig. 26, adjustable longitudinally in a sleeve 113 in a carriage 111 slidable by a screw and nut on a base member 108 adjustably mounted on the carriage 6; the member 108 is clamped to the carriage 6 by screws which are associated with eccentrics moving in slots in the member to permit variation of its axial position when tapered workpieces are to be ground. The spindle 114 is adjustable by a screw 115 and is clamped in position by a screw 117. On the end of the spindle 114 is clamped a slide 118 to which the diamond holder 119 is screwed. The grinding wheel 5. is trued by a diamond carried by a holder adjustable in a inclined bore in a carriage 99, Fig. 2, which is mounted for slidable movement on the carriage 4 by a screw and nut device. Water is pumped from the supply in the frame 1 through a pipe 107 and the axes of the screw and holder to the wheel 5.