Patent Publication Number: US-8534392-B2

Title: Composite cutting/milling tool having differing cutting elements and method for making the same

Description:
BACKGROUND 
     Cutting and milling tools are old in the drilling and completion industry. Crushed carbide tipped cutting and milling tools go back at least to 1945 and are very effective and hence ubiquitously used in the industry. The longevity of the commercial use of such tools is testament to their effectiveness in the field. And while crushed carbide is still being used today, and will likely continue to be used, improvements are always well received by the art. 
     SUMMARY 
     A cutting/milling tool includes a tool body; a cutting end of the tool body; a first plurality of cutting elements having a substantially identical shape disposed at the cutting end of the tool body; and a second plurality of cutting elements having a different shape than the first plurality of cutting elements, the second plurality of cutting elements being substantially identical in shape to each other, the second plurality of cutting elements being interspersed with the first plurality of cutting elements at the cutting end of the tool body. 
     A method for making a cutting/milling tool includes selecting a first plurality of consistently shaped and sized cutting elements; selecting a second plurality of consistently shaped and sized cutting elements; and attaching each plurality of cutting elements to a cutting end of the tool. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Referring now to the drawings wherein like elements are numbered alike in the several Figures: 
         FIG. 1  is an end view of a cutting or milling tool illustrating a plurality of cutting elements that include differing properties; 
         FIG. 2  is a perspective view of a cast carbide cutting element used in conjunction with the composite cutting/milling tool; 
         FIG. 3  is a view of another cast carbide cutting element used in conjunction with the composite cutting tool; 
         FIG. 4  is a view of another cast carbide cutting element used in conjunction with the composite cutting tool; 
         FIG. 5  is a view of another cast carbide cutting element used in conjunction with the composite cutting tool; 
         FIG. 6  is a front view of the cast carbide cutting element of  FIG. 2 ; 
         FIG. 7  is a top view of the cast carbide cutting element of  FIG. 2 ; 
         FIG. 8  is a side view of the cast carbide cutting element of  FIG. 2 ; 
         FIG. 9  is a front view of the other cast carbide cutting element of  FIG. 3   
         FIG. 10  is a side view of the other cast carbide cutting element of  FIG. 3 ; and 
         FIG. 11  is a top view of the cast carbide cutting element of  FIG. 3 . 
     
    
    
     DETAILED DESCRIPTION 
     Referring to  FIG. 1 , one embodiment of a composite cutting tool  10  is illustrated. The tool  10  comprises a tool body  11  having a cutting end  12  thereof provided with a plurality of cutting elements  14   a  and  14   b  (see  FIGS. 2 and 3 ). The elements  14  (collectively) comprise two or more pluralities of consistent shapes. In addition, one or more of the different shapes may also be of different size and different hardness. Each of the elements of like shape and size are substantially identical to each other. It is to be understood however that there are, in all embodiments, at least two pluralities of cutting elements that are different from each other at least in shape and that within each plurality of elements, the shape will be consistent. The like elements (a plurality of elements) may be either all of the same hardness or of different hardness. If a particular element is of a particular shape and/or size then all of the elements that are intended to be like that one will be substantially identical to it. Elements of another shape and/or size are likewise substantially identical to each other. It is further noted that shapes of elements may be duplicated in different sizes but the differently sized and shapes will form their own plurality of elements such that consistency within any particular plurality is maintained. 
     In order to achieve the sameness that is disclosed hereinabove. The cutting elements are preshaped in any suitable manufacturing process where randomness is avoided. In one iteration of the invention, the elements are all cast elements to ensure the sameness among shapes that are intended to be the same as each other. One composition for the elements is a sintered carbide material with a cobalt binder. The material itself will be familiar to those of skill in the art. 
     In a particular embodiment illustrated in  FIG. 1 , two pluralities of consistently shaped elements  14  are disposed over a surface of the cutting end  12  of the tool. In the illustrated embodiment, one plurality of elements  14   a  is shaped as illustrated in  FIG. 2  while the second plurality of elements  14   b  is shaped as illustrated in  FIG. 3 . It has been discovered by the Applicant that cutting/milling performance is improved by this configuration. Each of the plurality of elements  14  is attached to the tool body  11  using a media capable of bonding the elements  14  in place and that can withstand the rigors of cutting/milling in a downhole environment. In one embodiment, the material is a copper nickel braze. 
     In another embodiment, the elements  14  are arranged on the cutting end  12  so that ones of the plurality of elements having a greater hardness are positioned toward a periphery  20  of the cutting end  12  whereas ones of the plurality of elements having lesser hardness are arranged on the cutting end  12  of the tool  10  more toward an axis  22  thereof. This is helpful in cutting efficiency because the periphery of the cutting end  12 , when milling a packer for example, is exposed to the slips of the packer, which are harder than other portions of the packer. Cutting efficiency is improved hereby since the wear characteristic of the greater hardness elements at the periphery of the tool  10  are better matched to the task of milling the slips without premature dulling of the cutting elements. 
     As noted above, pluralities of elements  14  can be of differing sizes. This can provide a benefit to longevity of the tool  10  since the pluralities of elements having smaller size can be interspersed with those having larger sizes thereby reducing the potential for the surface being milled to come into contact with the attaching material. As one of skill in the art will recognize, attachment materials such as copper nickel braze become relatively lubricious when subjected to large shear forces inherent in cutting/milling operations. Therefore reducing potential shear force input to the material is a benefit. 
     Because of the consistent shape and size of elements  14 , tool dimensions are significantly more precise and repeatable than they have been in the past. This translates into reduce manufacturing costs and improved redressing success in the field. The method for making a cutting/milling tool as disclosed herein includes selecting at least two pluralities of cutting elements having a consistent shape and size. These elements are then attached to the tool body  11  by an attaching material such as copper nickel braze by brazing. The method may in some embodiments also include positioning individual ones of the pluralities of shapes having a greater hardness than other individual ones of the pluralities of shapes nearer a periphery of the tool  10 . 
     Referring to  FIGS. 4 and 5 , additional shapes of cutting elements  14   c  and  14   d  are illustrated. These shapes may be substituted for or added to the shapes of  FIGS. 2 and 3  in particular tools as desired. There will always however be at least two pluralities of substantially similarly shaped cutting elements attached to the tool body  11 . 
     While one or more embodiments have been shown and described, modifications and substitutions may be made thereto without departing from the spirit and scope of the invention. Accordingly, it is to be understood that the present invention has been described by way of illustrations and not limitation.