Patent GB-1373765-A (GB)
Title: Grinding machine
IPC: B24B47/20
Filed: 1971-10-29
Abstract: 1373765 Grinding ING C OLIVETTI & C SpA 29 Oct 1971 [30 Oct 1970 (2)] 50469/71 Heading B3D [Also in Division F2] Fine feed of the wheel head 3 of a grinding machine is produced by a lead screw and nut arrangement in which the lead screw is fixed against rotation while the nut which is secured to the wheel head, rotates under the drive of a stepping electric motor, means being provided to move the lead screw axially for rapid feed. The head, Figs. 2, 3, carrying a motor 32 driving the grinding wheel shaft 25, is slideable on bearings 24 along guides 5, 6 on a bed 7, the bed being angularly adjustable about a pivot 2 after its weight has been partially relieved from the machine frame by hydraulic cylinder and bearing means 16-18, 22, 23. Rapid movement of the head is achieved by piston and cylinder  means 42, 43, the piston-rod being integral with the lead screw 40. Means 87, 88, protect the guides 5, 6 in all positions of the head. The nut 36 is in two parts secured to a common sleeve (53) and of the recirculating ball type. Figure 4 (not shown). It is rotated by a stepping motor 38 through a gear train. The lead screw is prevented from rotating by an arm 72 secured to it and having an end sliding in a guide 73 in the head. A stop 49 mounted in the bed limits the advance of the lead screw by the piston and movement of the nut 36 along the lead screw 40 is checked by one of a series of dogs 75 on the nut engaging a stop 77 on the lead screw.  Workhead.-Means is provided for advancing the workhead a small distance, e.g. 2 mm. towards the wheel to, e.g. produce a shoulder. In one arrangement, Fig. 7, the spindle 114, hollow and designed to receive a workpieceholding collet (riot shown) is supported in hydrodynamic bearings 116, 117, the bearing 116 being slideable in the head with the spindle to produce the required movement of the latter. A stepping motor 186 rotates a gear 192 having an internal thread engaging a threaded ring 170. The ring is secured to the bearing 116 and forms with it a recess for a thrust collar 173 fast with the spindle. Oil fed to the bearing through passages 182, 181, 121, 123 reaches the thrust ring via a passage 178. The spindle 114 is driven by a belt 164 and pulley 143 from a motor (113) Fig. 6 (not shown), in the workhead, connection between the pulley and spindle being connectible or disconnectible by sliding a plate 146 in a groove 145 in a ring 144 attached to the pulley and locking it with a bolt 147. The plate 146 engages a recess 148 in the spindle. A similar arrangement 199, 201 at the other end of the spindle is used to lock the latter against rotation when required. In an alternative arrangement, Fig. 8, the respective bearing 206 is fixed but the spindle 114 is moveable axially by a lever 216 pivoted about a fulcrum 220 by a screw 225 rotated in a fixed nut 226 by a stepping motor 215. The lever engages a ring 233 through a pair of diametrically opposed rollers 222 to force the ring against a thrust collar 237 on the spindle. To enable play to be taken up on the bearings 206, each comprises a coned bush 208, adjustable axially relative to a similarly coned housing 207 by rings 213. Tightening up of the left hand ring 213, as shown, reduces the play. The workhead is also angularly adjustable about a vertical axis, Figs. 5, 6 (not shown).