Method of applying a wear-resistant layer to a surface of a downhole component

Abstract

A method of applying a wear-resistant material to a surface of a downhole component for use in subsurface drilling comprises forming a plurality of bearing elements, applying a layer of an electrically conductive, less hard material to each bearing element, and then bonding each bearing element to the surface of the component by welding or brazing to the surface of the component a part of the surface of the bearing element which comprises said less hard material, wherein the layer is of thickness greater than 0.05mm.

Description

[0001] This is a Continuation-in-Part of U.S. Patent application Ser. No. 09 / 340,984, filed Jun. 28, 1999, by Stephen Martin Evans, et al., entitled "Method of Applying a Wear-Resistant Layer to Surface of a Downhole Component" now pending.[0002] 1. Field of the Invention[0003] The invention relates to methods of applying a wear-resistant material to a surface of a downhole component for use in subsurface drilling. The method is suitable for use both with drill bits and with other downhole components.[0004] 2. Description of Related Art[0005] The invention is applicable to downhole components of the kind which include at least one surface which, in use, engages the surface of the earthen formation surrounding the borehole. The invention relates particularly to rotary drill bits, for example of the drag-type kind having a leading face on which cutters are mounted and a peripheral gauge region for engagement with the surrounding walls of the borehole in use or of the rolling cutter ki...

AI Technical Summary

Benefits of technology

[0016] The use of a layer of less hard material of thickness greater than 0.05mm is advantageous in that it is capable of carrying the electrical current applied thereto during a resistance welding operation without breaking down. The thickness of the layer preferably falls within the range of 0.1mm to 0.3mm. More preferably, the layer thickness falls within the range 0.15mm to 0.25mm, and conveniently within the range of 0.15 to 0.2mm.

[0017] The use of a layer of thickness falling within the range 0.15mm to 0.2mm is advantageous in that the resistance welding operation can be performed relatively easily. After securing the bearing elements in position, a layer of a hard facing material may be applied over and around the bearing elements. The layer may be of depth such that the bearing surfaces of the bearing elements are left exposed, or the bearing surfaces may be covered, some of the hard facing material subsequently being removed, either before or during use.

[0020] The methods of the invention may also be applied to increase the wear-resistance of surfaces of roller-cone bits or other types of rock bit.

Problems solved by technology

This is a particular problem with steel bodied drill bits where the gauge of the bit comprises a single surface extending substantially continuously around the whole periphery of the bit, for example as described in British Patent No. 2326656.

While TSP has the wear-resistance characteristics appropriate for a bearing element on a downhole component, it has hitherto been difficult to mount TSP on downhole components.

Where a bearing element is to be applied to a surface of a downhole component for the purpose of wear-resistance, however, it is preferable for the bearing element to be mounted on the surface of the component, particularly if the component is formed by machining, from steel or other metal, so that the bearing element cannot readily be embedded in the component.

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