TECHNICAL FIELD OF THIS INVENTION : This invention is in the field of a part of the pulverization equipment of coal in a Thermal Power Station [TPS]. More particularly, this invention relates to improved multi-segment hardened, wear resistant sleeve for oil seal portion of roller journal shaft of Raymond and similar type of mills and oil seal/gland packing portion of similar shafts; and specifically to contriving a sleeve which shall be in multi-segments and not a sleeve in one piece.

Earlier, in India, this inventor has submitted, on the same subject, the Patent Application with Complete Specification under Patent Appln. No 242/BOM/98 dated 23/4/1998.

BACKGROUND ART: Presently the roller journal shafts are widely used in coal mills of thermal power stations (TPS), cement plants, steel plants and the like industries wherein it is a matter of observation that in any assembly of roller journal shaft assembly, there is provided an oil seal to prevent pulverized material entering the bearings on the journal shaft. It is to be particularly noted that pulverized coal is abrasive in nature. The oil seal, for various reasons, creates groove on the journal shaft. Once the groove is formed, the ingraced dust causes bearing failure. To prevent groove formation, there is no practice to provide wear resistant sleeve on the oil seal portion of the roller journal shaft of the Raymond type of coal-mill. In some other cases of shafts, however, it is a matter of initial design that some shafts have

been fitted with single piece sleeve but necessarily involving more work of refitting whenever or wherever it is to be re-fitted.

Fittment, removal or replacement of single piece sleeve necessitates removal of bearings and/or any component e. g. impeller, roller assembly mounted on the shaft and the like. The process of removal of bearings very often damages the bearings themselves creating necessity of replacement of bearings. This involves cost and time for refitting ; apart from cost of bearings, plus non-availability of the mill. It is known that the removal of bearings very often causes seating portion of the bearings on the shaft to become undersize.

It is also the observation/s that oil seal portion with grooves also need repairs.

Such shafts with grooves and/or undersize bearing seating portions have to be disassembled and dismantled of whatever is mounted on them and removed to repair shops for tedious known processes of build-up by known processes and machine down to size and return to site for re-fitment and re-assembly. It is also known that welding, which is one of the known processes of build-up, introduces often difficult to correct run-outs and stresses. Shafts have to be discarded if run-outs are beyond correctable limits. Shafts with induced stresses can be stress relieved by expensive and time consuming known processes of heat treatment and the like. Such induced stresses accelerate fatigue, making the shafts prone to premature failure.

DISCLOSURE OF THE INVENTION : Object of the present invention, therefore, aims at devising multi- segment sleeve for prepared roller journal and the like shafts whereby the initial fitment or reversed fitment or replacement fitment of the sleeve can be done without the need of removing the bearing ; that means in short, object of the present invention aims at manufacturing roller journal shaft with multi- segment sleeve ; &, secondly, even if the sleeve is required to be changed, it drastically reduces down-time, and it can instantly be changed being a multi- segmented construction without requiring the bearings to be removed; and so,

providing multi-segment sleeve is better than a single piece sleeve which in turn is better than no sleeve at all.

According to the yet another object, the most salient feature of the present invention, the multi-segment sleeve provides facility of changing the sleeve if and when necessary without requiring to remove the shaft from the site.

According to yet another object the sleeve can be used twice, by reversing the sleeve. This is possible and achieved with reversible sleeve marginally wider than single piece sleeve. This new sleeve offers space for second time re-use. The placement position of sleeve over the shaft plays an important role.

According to yet another object, this invention delays (if not eliminates) the formation of groove and subsequent losses.

DRAWINGS: The invention will now be described with the help of a drawings accompanying this specification wherein salient features have been shown by suitable numerals and referred to appropriately in the following description.

Figures are schematic. Drawing comprises 3 figures.

Fig. 1 shows schematic view of a typical sub-assembly of journal in vogue for pulverizing coal or such other materials on very large scales at thermal power stations, (TPS), cement factories and the like. In fig. 1, journal head assembly and skirt are not shown.

Fig. 2 shows perspective of the multi-segment sleeve for roller journal and the like shaft as per present invention; while, Fig. 3 shows a variation in the construction of multi-segment sleeve.

Referring to figures, fig 1 shows the background art wherein the roller journal assembly is shown to comprise roller journal shaft (2) having tapered trunnion seat (3), an oil seal (5) kept within upper journal housing (6), the shaft (2) extends downwards and there is provided a bearing (7) on the upper portion and another bearing (8) at the lower portion of the shaft. Upper

bearing (7) is kept in upper journal housing (6). The lower bearing of the shaft is in lower journal housing (9). The spacer (13), a locking plate and nut (10) are also provided in the assembly. The lower journal housing carries a grinding roll (11). The grinding roll (11) is secured to lower journal housing (9) by lock-nut (12). This is, in general, a very well known assembly for the roller journal shaft used in Raymond type pulverizing mills.

Referring to figs. 2 and 3 which show the multi segment sleeve and the roller journal shaft as per present invention, there is created recesses (12), width of which will be adequate to accept and accommodate sleeve (4). The seat may be circumferentially circular or as a variation it could be polygonal with corresponding inner surface (15) as distinctly seen in fig. 3. The roller journal shaft (2) is having its tapered trunnion seat (3), below that there is provided recess (12) matching the inner portion of the split sleeve (4).

According to significant novel feature, the sleeve is a multi-segment contraption (4) having holes (16) for fixing the sleeve over the recessed portion.

According to salient feature of the present invention, multi-segment sleeve provides facility of reversing or replacing the sleeve, in situ, as and when necessary without requiring to remove the shaft from the site.