Metal fusion bonding – Process – Repairing – restoring – or renewing product for reuse
Patent
1998-09-04
2000-07-11
Ryan, Patrick
Metal fusion bonding
Process
Repairing, restoring, or renewing product for reuse
228119, 428558, B23K 3100, B23K 3102
Patent
active
060859636
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a repair procedure for use in work pieces and especially but not exclusively with drill stem stabilisers as used in drilling equipment for the exploitation of natural oil and gas reserves.
The traditional method of repairing worn drill stem stabilisers involves the use of a flame brazing technique, the flame typically being generated by the combustion of a mixture of oxygen and acetylene. The worn area is subjected to the heat generated by the brazing technique prior to tungsten carbide trapezoids being placed, in an ordered formation, upon the heated area. The trapezoids are subsequently surfaced with a brazing material impregnated with small tungsten carbide particles sufficient to cover the area of the repair.
The process employs a high heat input which can exceed that recommended for the drill stem material. This excess heat can have an adverse effect on the structural integrity of the stabilizer as well as reducing its resistance to wear by abrasion. Further, considerable time was required to apply this method in a repair.
It is the object of the present invention to obviate and/or mitigate the aforementioned disadvantages associated with this type of repair procedure.
According to a first aspect of the present invention there is provided a method of repairing a worn work piece comprising locating a plurality of hard wearing elements in spaced array on the surface of a metal work piece to be created and applying filling material in the space between the elements by a relatively low temperature fusion welding process.
According to a second aspect of the present invention a method of repairing a worn work piece especially a drill stem stabilizer of a downhole tool comprises applying a buffer layer to the zone to be repaired by means of a relatively low temperature fusion welding process; fitting a plurality of elements of hard wearing material on the buffer layer; providing a filling between the elements preferably by the aforesaid fusion welding process; and applying surf acing of suitable material over the filling.
Preferably the fusion welding temperature is substantially below the tempering temperature of the work piece being treated.
The fusion welding process is preferably in the form of a semi-automatic metal active gas process (MAG). The initial (pre) heating of the zone to be treated can be carried out at a temperature less then 100.degree. C. and preferably about 50.degree. C. The hard wearing elements preferably comprise tungsten carbide members of trapezoidal form.
A retainment, for example of bar form, can be located around the periphery of the zone where the buffer layer is to be applied; to facilitate buffer layer formation. The welding process can use argon as a shielding gas for the weld pool. The filler material can be of any suitable material and copper, aluminium and bronze materials are possibilities for use in this material The surfacing can include brazing and tungsten particles.
The surfacing can be applied by a brazing process, and there should be no real harmful effect as the brazing in this case is onto the buffer or fill layers away from the basic fin metal.
The work piece repair method in accordance with the present invention can be used in the treatment of work pieces both of magnetic steel e.g. with a percentage composition C: 0.410; Mn 0.940; Si: 0.240; S: 0.021; P; 0.011; Ni 0.180; Cr: 1.120; Mo: 0.230; Cu: 0.210 and non-magnetic steel e.g. with a percentage composition C: 0.025; Mn: 20.51; Si: 0.46; Cr; 12.57; Mo: a 13; Ni: 0.10; No: 0.28.
According to a further aspect of the present invention in a repair method of a zone of a work piece having an exially extending path, especially a stabiliser fin extending axially on a downhole tool, a plurality of hard wearing elements, for example of trapezoidal form, are set in an array extending at an angle to said axially extending path of the work piece zone.
The present invention is also a work piece with hard wearing elements of a repair arranged as above.
Embodiments of the present invention w
REFERENCES:
patent: 604569 (1898-05-01), Ringstrom
patent: 1342801 (1920-06-01), Gebauer
patent: 4011918 (1977-03-01), Jurgens
patent: 4156374 (1979-05-01), Schwayder
patent: 4243727 (1981-01-01), Wisler et al.
patent: 4277108 (1981-07-01), Wallace
BGM (Patents) Limited
Edmondson Lynne
Ryan Patrick
LandOfFree
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