Patent GB-1269238-A (GB)
Title: Improvements relating to tool heads
IPC: B24B27/00
Filed: 1969-05-28
Abstract: 1,269,238. Grinding; trueing grinding wheels. ATOMIC ENERGY OF CANADA. 28 May, 1969 [17 Sept., 1968], No. 27055/69. Heading B3D. A method of redressing the cutting surface of a grinding wheel 610, Fig. 4F, such that the depth of cut after redressing is substantially the same as that before redressing comprises moving the wheel diametrically in a selected direction by a distance X units, moving a dressing tool 548 having an axis of movement during dressing disposed parallel to the axis of rotation of the wheel in the same selected direction a distance 2X units from that used for initial dressing of the wheel, and redressing the wheel. The method is applied in the operating of a tool head used to remotely grind the sealing surfaces of the upper and lower headers, Fig. 1, of a nuclear reactor vessel, the tool being carried by one of three arms, Fig. 3A, extending from a main stem passed through access holes in the reactor vessel. Each of the arms carries rocking members provided with rollers for engaging the sealing surfaces and a spigot projecting therefrom for centralizing the main stem. The roller assemblies and the tool head are indexable through 180 degrees so that the upper and lower sealing surfaces can be ground. The tool head has a tubular part 1, Fig. 4, provided with lugs for securing the head to one of the arms and carries an indexing head 2 for indexing the tool through the 180 degrees, a vertical slide 3 and a grinding head 4. The tubular part 1 consists of an outer tube 101 within which is a rotatable and axially slidable second tube 201, Figs. 4C and 4D. A pair of plates 120, 122 rotatably mounted on the outer tube and one of the plates is formed with a pair of tapered apertures 124 selectively engageable by a plunger 109 slidably mounted on a housing 110 carried by rings 107A, 107B secured to the outer tube. When the plunger is retracted the plates 120, 122 can be rotated to index the grinding head by operation of a motor 224 driving a pinion 226 engaging a gear 222 secured to the plate 122 which is secured to plate 120 by studs 114. The inner tube 201 is guided for axial movement in plate 122 by a key 242 and slot 240, the axial movement being effected by an hydraulic cylinder in the left hand end of the outer tube 101. The inner tube 201 carries at its end a plate 316 formed with a vertical dovetail guide for a slide member 334 attached to a block 330. A pair of rollers 342 engage inclined tracks 340 on the block and are movable by an hydraulic piston and cylinder device 213, 219 mounted in the inner tube to effect vertical movement of the slide. The slide carries a pair of plates 440, Fig. 4F, to which is secured a plate 460 having a dovetail guide for a dressing slide 470 carrying a sleeve 522 for axial movement of a shaft 530 which, at one end, carries the dressing tool 548. The other end of the shaft is in threaded engagement with a nut 528 rotatable through gearing by a motor 516 to effect movement of the diamond parallel to the axis of the grinding wheel 610. The latter is carried by a bearing housing 600 mounted on a slide 496 movable in dovetail guides in a further fixed plate 478. A pinion 501 is rotatably mounted in the grinding wheel slide 496 and engages a rack 472 in the dressing slide 420 and a rack 490 in the fixed plate 478, the engagement of the pinion with the racks being adjustable by wedges 474, 492. During grinding of the sealing surfaces of the reactor, when redressing is necessary, the grinding head can be retracted by actuation of the device 213 moving the rollers 342 so that the slide 334 carrying the head is moved away from the surface being ground. Thereafter a rotary solenoid is pulsed and through worm gearing rotates the pinion 501 which is mounted on the grinding wheel slide 496 and reacts with the fixed rack 490 to move the wheel slide a distance X units. The pinion also causes the rack 472 on the dressing slide to move the latter a distance 2X units so that the dressing tool moves twice the distance of the grinding wheel. Motor 516 is then actuated to traverse the diamond across the grinding wheel. After dressing, the device 213 returns the wheel to continue grinding. The grinding wheel is belt driven from an air motor. Rollers 860 carried by outriggers 856 act as steadying means.