In repairing the TIMKEN bearings, a common method of heat treatment quenching, tempering, annealing, and so three, tool is a spirit lamp, and Blowpipe, method is simple, but very practical.
Parts of the file system are generally hardened, to increase the hardness of parts, laying the foundations for polishing, polishing.
Quenching is the wet steel parts of the file system, some surface dipped in borax, burn Red in the spirit lamp l with a Blowpipe, put in the oil. Parts surface coverage of borax in order to prevent parts of decarbonization phenomena. Broken parts as a result of the fire on the surface with a layer of borax, black.
Must be removed before tempering. It is the parts put water with borax in a copper container, and seven heated boiling alcohol lamp, automatically on the borax from the part fell off.
Part is very hard, brittle, as quenching, tempering treatment must be carried out, achieving suitable hardness. Usually quenched parts placed on the copper plate, heating in the spirit lamp, make the parts stops heating after Brown, natural cooling in the air. Parts tempering hardness is generally between Rockwell hardness r C55-62. TIMKEN bearings machine parts (steel) hardness requirements recommended in the appendix in NV.
(1) expands the scope steel GCr15, General steel GCr15 m quench ring when the effective thickness is below 12mm, but due to nitrate BL quench cooling ability is strong, the use of measures such as mixing, String, add water, ring wall thickness can be effectively expanded to about 28 mm.
(2) stable hardness, good uniformity
Due to BL changes is a slow process, General GCr15 steel needed 4h,GCr18Mo steel needed 5h, rings in nitrate in the long time isothermal, surface heart Department Organization changes almost while for, therefore hardness stability, and uniform sexual good, General GCr15 steel BL quenching Hou hardness in 59~61HRC, uniform sexual ≤ 1 HRC, does not as m quenching Shi rings wall thick slightly large some on appears hardness low, and soft points, and uniform sexual poor problem.
(3) reduction of hardening, grinding cracks
In railway, and non-marked bearing production in the, due to rings size large, and weight heavy, oil quenching Shi m organization brittle large, for makes quenching Hou obtained high hardness often take strong cooling measures, results led to quenching micro-crack; and BL quenching Shi, due to BL organization than m organization toughness good was more, while surface formed up to -400~-500MPa of pressure stress, great to reduces has quenching crack tendencies [19]; in mill processing Shi surface pressure stress offset has part grinding stress, makes overall stress level declined, Significantly reduces grinding cracks.
(4) the bearing service life
For bear large shock load of railway, and deep ditch ball bearing,, by m quenching Hou using Shi main failure forms for: Assembly Shi within sets cracking, using process in the by shock outer ring retaining edge off block, and within ring fragmentation, and isothermal quenching bearing due to shock toughness good, and surface pressure stress, regardless of Assembly Shi within sets cracking, also is using process in the coat retaining edge off block, and within sets fragmentation tendency greatly reduces, and can reduced roll child of edge stress concentrated. Therefore, m-quenched after austempering than average life expectancy and increased reliability.

 


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