| 摘要 |
machine engineering and metallurgical industry branches, namely manufacture of cogging mills. SUBSTANCE: support unit includes bushing mounted on roll chock assembly, two steel hardened discs engaging one with another along their spherical surfaces and placed between bottom of bushing body and screw. Lower disc is fixed against rotation inside bushing by means of key. Between screw and hardened discs there is thrust bearing unit made of antifriction material. Novelty is annular flat hardened pivot resting upon built-up thrust bearing and secured to flange of screw head by means of collars and bolts. Built-up thrust bearing includes steel supporting plain-spherical disc and changeable annular disc of antifriction material secured to supporting disc by means of cylindrical pins. Thrust bearing is arranged is such a way that its hardened spherical surface is mounted in hardened disc-seat. Lubrication system of thrust bearing includes telescopic casing of screw; funnel for accumulating oil; through inclined openings passing from thread recesses and funnel into cavity of screw; concave cone surface provided on lid of bushing; annular groove on upper end of screw, even number of radial and lubricating ducts on both ends of pivot; through central and radially arranged vertical openings joining said grooves; turning made in head of screw and having diameter equal to 3/4 of outer diameter of screw head and providing cavity for accumulating oil in screw; cylindrical turnings made in ends of pivot and mutually joining radial and lubricating grooves; metering disc mounted by means of pins in upper turning of pivot and having central and peripheral vertical openings and metering ball-type valves arranged in turnings over peripheral vertical openings. Radius of sphere of valve seat is more than that of ball. Metering disc has at side of pivot inner stepped turning forming together with upper turning of pivot cavity for oil accumulation in metering unit. Said cavity is joined with peripheral vertical openings of metering unit and with radial grooves of pivot. Lubrication system also includes breather pipe mounted on metering unit in screw cavity; central turning of lower pivot end having diameter no less than 0.4 of diameter of pivot itself and forming together with turning in thrust bearing additional cavity for oil accumulation joined by means of radial grooves with lubricating grooves of pivot. Vertical openings between radial and lubricating grooves at side of lower end of pivot are provided with cone turnings with angle no less than 90 degrees, with depth no less than 0.25 of pivot height. Vertical openings of adjacent grooves are arranged in staggered fashion. Openings in groove are arranged non-uniformly relative to mean circle of annular pivot, namely: at outer side quantity of openings is more than at inner side. Thrust bearing is fixed against rotation relative to body of bushing by means of protrusions of supporting disc inserted to vertical slots in walls of bushing. Keys fixing thrust bearing and disc-seat are arranged one normal to another in such a way that first ones are arranged along rolling line. Spherical contact surfaces of disc-seat and thrust bearing have reciprocal convexity with sphere radius selected according to condition of tangential contact of force received in the result of total action of strip metal upon upper roll with sphere of thrust bearing at non-stable period of rolling process ( at guiding strip between rolls) while taking into account maximum angle value of strip biting between rolls in reversing cogging mill and outer diameter of pivot. Layer of grease such as molybdenum disulfide (MoS2) is applied onto surfaces of spheres of supporting disc of thrust bearing and disc-seat. Supporting disc of thrust bearing has skirt providing oil closure preventing oil penetration to zone of contact of spheres of thrust bearing and disc-seat. EFFECT: significantly increased strength of members of support unit and screw pair, their uniform wear due to rational lubrication depending upon operation modes of screw |
