Centrifuge tile

Details Centrifuge tile Centrifuge tile

1999-10-25

2001-05-15

Shaw, Clifford C. (Department: 1725)

Metal fusion bonding

Process

Plural diverse bonding

C228S212000

Reexamination Certificate

active

06230960

ABSTRACT:

FIELD OF THE INVENTION
This invention relates to a tile eg of tungsten carbide, for installation with a plurality of similar tiles, in or on a component of a centrifuge, such as the scroll of a centrifuge, in locations of predicted high wear.
BACKGROUND OF THE INVENTION
It is known to install such tiles by the steps by
1) preparing each tile prior to a s sembly, by marking the face with a temperature sensitive paint or crayon eg “Tempil Stick”, which will indicate if the maximum allowable temperature of 120° C. is exceeded during a welding stage;
2) preheating the tile to 50° C.;
3) inserting a 0.5 mm shim between the tile being fitted and the adjacent tile and secure the tile correctly and firmly into place using a ‘G’ type clamp and removing the shim;
4) welding tile on to the flight of a centrifuge scroll etc, using short stringer beads; and
5) before removal of the ‘G’ clamp, visually checking all welds and repairing cracks which may have formed as a result of cooling.
Furthermore, any tile assembly that is shown to have been heated to a temperature in excess of 120° C. during welding must be removed and replaced by a new tile, as the epoxy bond or a brazing interface of the overheated tile is likely to have been impaired.
Furthermore, considering tiles applied to the flights of a centrifuge scroll, the existing prebonded tile and carrier combination which comes in one size, has to be ground to fit the diameter variations on the tapered portion of the flights, so as to give a smooth and continuous surface.
OBJECT OF THE INVENTION
A basic object of the invention is the provision of an improved method of tile installation eg on a scroll of a centrifuge, and a scroll and a centrifuge incorporating such tiles.
SUMMARY OF A FIRST ASPECT OF THE INVENTION
According to a first aspect of the invention there is provided a method of installing tiles via interposed tile carriers on a scroll of a centrifuge comprising
(i) mounting each tile carrier prior to a welding step in the required position on a centrifuge flight by means of an individual tile clamp, with mechanical inter-engagement between each tile carrier and its clamp, thus positioning each tile carrier in the same position relative to its clamp on each application, the tile clamps being of a set width, so that when mounted side by side they pitch the tile carriers so that when the tiles are inserted there are no gaps between the tiles, thus giving a smooth surface without having to dress the tiles;
(ii) welding tile carriers, whilst held in position by the tile clamps (from single to multiple batches) to the centrifuge flight; removing the tile clamps; and
(iii) once the tile carriers have cooled down to ambient temperature; inserting the tiles and securing the tiles to their respective tile carriers.
The mechanical inter-engagement between each tile carrier and its clamp may conveniently be a male/female inter-engagement such as a slot and rib, but preferably is an index pin on the clamp which aligns with and engages a hole in the tile carrier.
Although the securing of the tiles to their respective carriers could be effected at a brazed interface, preferably an epoxy adhesive is employed.
SUMMARY OF A SECOND ASPECT OF THE INVENTION
According to a second aspect of the invention, of independent significance, there is provided a method of inserting a tile having a dovetail rib in a carrier having a dovetail groove, comprising:
(i) arranging the rib and groove tolerances such that firstly a lower edge of the tile is inserted into the lower dovetail groove; secondly the tile is rotated to bring its upper dovetail rib within the dovetail groove, and thirdly, the tile is retracted so that angled surfaces of the dovetail rib seat on the angled surfaces of the dovetail groove, and
(ii) securing the tile in position, preferably with an injected epoxy resin.
Thus, in accordance with this second aspect, each tile is inserted frontally/radially into its carrier, in contrast to prior art proposals (c.f. FIG. 10 of WO 81/02853) where lateral insertion has been employed. It follows that the tiles and carriers need to be produced to close tolerances to make frontall insertion possible, by engaging a lower face of each tile on a support surface of the groove of its carrier and rotating the tile towards the carrier.
SUMMARY OF A THIRD ASPECT OF THE INVENTION
According to a third aspect there is provided a centrifuge scroll incorporating tile carriers and tiles installed in accordance with the first or second aspects.
SUMMARY OF A FOURTH ASPECT OF THE INVENTION
According to a fourth aspect, there is provided a centrifuge incorporating a scroll in accordance with the third aspect.


REFERENCES:
patent: 3764062 (1973-10-01), Brautigam
patent: 4006855 (1977-02-01), Merzenich
patent: 4785769 (1988-11-01), Black
patent: 4821478 (1989-04-01), Cremer et al.
patent: WO8102853 (1981-10-01), None
Patents Act 1977 Search Report under Section 17 (Search Report relating to a corresponding British patent application).

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