GB1385287A - Honing machines - Google Patents

Abstract

1385287 Honing TOYO KOGYO CO Ltd 6 Aug 1973 [11 Aug 1972 22 Aug 1972 (2) 26 Aug 1972] 37300/73 Heading B3D A honing machine comprises a rotary member 2a for supporting a honing stone 2, drive means for rotating the stone, and advance means for feeding the stone radially outwardly of the rotary member having, in combination, a constant-pressure advance mechanism and a constant speed advance mechanism, and means for automatically selecting whichever one of the two mechanisms is faster in advance speed than the other for feeding the honing stone. The honing machine has a main body 1, Fig. 3, supporting a shaft 2a, Fig. 4, which is rotated by drive means engaging a gear 2b in the shaft. The honing stone 2 is supported for radial movement in the shaft 2a upon longitudinal movement of a wedge 3 coupled to a rack 23 engaged by a pinion 22 connected by bevel gearing 20, 21 to a pinion 9 meshing with a rack 4a on a rod 4. One end of the rod is connected to the piston 6 of a constant pressure advance cylinder 5, and the other end of the rod is abutted by the head of a constant speed advance screw 7 which is engaged in a cylindrical screw 10 and maintained in contact with the rod by a low force drive connected by a rack 12 and pinion 11 to the screw 7 or a turbine drive (Fig. 5, not shown). The cylindrical screw 10 is formed with a gear 14 engaging a worm 13 driven by a constant speed advance motor 19, such as a pulse or stepping motor, the cylindrical screw being held against rotation by a key 16. In operation, the stone 2 is inserted in the bore of a workpiece and the shaft 2a is rotated by the drive 2b while the frame 1 is axially reciprocated. A control means 18 acts on a control valve 17 to supply fluid under pressure to port A of the constant pressure cylinder 5 and also acts to start the constant speed motor 19. Initially, the advance of the stone 2 by movement of the wedge is effected by the movement of the piston of the constant pressure cylinder, the screw 7 being maintained in abutment with the rod 4 by the drive 12. As the grinding surface becomes filled, the advance speed is reduced until it reaches that determined by the drive from motor 19 rotating the cylindrical screw 10 which thereby advances rod 4, and hence the stone 2, at a constant speed. The arrangement may be such that the speed of advance is such as to effect self-dressing of the honing stone so that the advance is again effected by the constant pressure cylinder 5 until filling of the stone again results in the stone being advanced at the constant speed. A number of other embodiments are described which incorporate one-way clutches which enable the constant speed advance drive to advance the honing stone when its speed of advance under constant pressure falls to that of the constant speed. The constant pressure advance cylinder may be associated with a further cylinder for returning a predetermined quantity of fluid to the advance cylinder so that the honing stone is returned a predetermined distance irrespective of wear of the stone. The constant pressure advance mechanism and constant speed advance mechanism may act on respective racks engaging a common pinion to eliminate the effect of backlash.