Patent Application
20080006447
The invention may be understood by reference to the following description taken in conjunction with the accompanying drawings, in which like reference numerals identify like elements, and in which:
While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the drawings and are herein described in detail. It should be understood, however, that the description herein of specific embodiments is not intended to limit the invention to the particular forms disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims.
Illustrative embodiments of the invention are described below. In the interest of clarity, not all features of an actual implementation are described in this specification. It will, of course, be appreciated that in the development of any such actual embodiment, numerous implementation-specific decisions must be made to achieve the developers' specific goals, such as compliance with system-related and business-related constraints, which will vary from one implementation to another. Moreover, it will be appreciated that such a development effort might be complex and time-consuming, but would nevertheless be a routine undertaking for those of ordinary skill in the art having the benefit of this disclosure.
The present invention will now be described with reference to the attached drawings which are included to describe and explain illustrative examples of the present invention. The words and phrases used herein should be understood and interpreted to have a meaning consistent with the understanding of those words and phrases by those skilled in the relevant art. No special definition of a term or phrase, i.e., a definition that is different from the ordinary and customary meaning as understood by those skilled in the art, is intended to be implied by consistent usage of the term or phrase herein. To the extent that a term or phrase is intended to have a special meaning, i.e., a meaning other than that understood by skilled artisans, such a special definition will be expressly set forth in the specification in a definitional manner that directly and unequivocally provides the special definition for the term or phrase.
In general, the present invention is directed to the formation of one or more planar reference surfaces on the bearing spindle 16 and/or rolling cutter 18. The planar reference surfaces are substantially perpendicular to a centerline of the bearing spindle 16 and/or rolling cutter 18. In other embodiments, the planar reference surface may be substantially parallel to a thrust face formed on the spindle 16 and/or rolling cutter 18. Such planar reference surfaces may be used in gauging and/or inspecting rolling cutter drill bits 10 in which the accuracy of locating bearings at desired positions may be improved. More specifically, with the improved precision offered through use of the present methodologies disclosed herein, bearing loading may become more uniform and predictable, and bearing life may be increased, as the improved precision may allow for a reduction in axial play.
As shown in
Through use of the planar reference surface 60H depicted in
In some cases, the planar reference surfaces described herein to be used as a reference point for adjusting or accommodating variations in a manufacturing tool. For example, in some cases, the cutting tool on a numerically controlled machine tool may need to be changed for a variety of reasons, e.g., wear. In such cases, due to replacement of the cutting tool, the planar reference surfaces described herein may be employed to establish a horizontal offset relative to the surfaces defined by the original worn cutting tool. The numerically controlled machine tool may then be adjusted to compensate for such a variation internally within the tool.
The present invention is generally directed to various embodiments of a roller cone drill bit that includes planar reference surfaces for use in gauging and/or inspection during the manufacture of a rolling cutter drill bit 10. In one embodiment, any tool that is used to machine or grind the race 43 will also be used to machine or grind the reference surface 60H using the same offset. Using this methodology, the variations between the reference surface 60H and the ball race 43 is as small as the inherent accuracy of the manufacturing tool. In effect, this methodology allows the reference surface 60H and the ball race 43 to be treated as a single unit. Given that there are very accurate measurement techniques and instruments for measuring the distance between two parallel flat surfaces (e.g., the reference surface 60H and the thrust face 45), this same accuracy would apply to the thrust face/ball race positioning as well. It should be understood that the thrust face 45, ball race 43, reference surface 60H and centerline 17 may be manufactured in any order. However, the reference surface 60H and ball race 43 are normally “cut as one.”
In one illustrative embodiment, a method of manufacturing a drill bit 10 is disclosed which comprises forming a planar reference surface 60H in a ball race 43 of a component of the drill bit 10 and using the planar reference surface as a reference point in positioning the component in a manufacturing tool. In one particular embodiment, the planar reference surface 60H is substantially perpendicular to a centerline of the component.
In one illustrative embodiment, the drill bit 10 comprises a bearing spindle 16 comprising a bearing race 43, a rolling cutter 18 positioned around the spindle, the rolling cutter 18 comprising a bearing race 43, and a planar reference surface formed in the race of at least one of the bearing spindle 16 and the rolling cutter 18. The reference surface 60H may be substantially perpendicular a centerline of these components. In some cases, a reference surface may be formed in the race 43 formed in each component.
The particular embodiments disclosed above are illustrative only, as the invention may be modified and practiced in different but equivalent manners apparent to those skilled in the art having the benefit of the teachings herein. For example, the process steps set forth above may be performed in a different order. Furthermore, no limitations are intended to the details of construction or design herein shown, other than as described in the claims below. It is therefore evident that the particular embodiments disclosed above may be altered or modified and all such variations are considered within the scope and spirit of the invention. Accordingly, the protection sought herein is as set forth in the claims below.
