Patent Application
20140000428
1. Field of the Invention
The invention relates generally to the design of circular saw blades. In particular aspects, the invention relates to the design of saw blades used in mechanical pipe cutting tools.
2. Description of the Related Art
Circular saws are used in a wide variety of applications. Circular saw blades are used, for example, in pipe cutting tools, such as the Mechanical Pipe Cutter™ (MPC™) electromechanical pipe-cutting tool which is available commercially from Baker Hughes Incorporated of Houston, Tex. These devices cut a pipe from the inside. During operation, the saw blade is moved in a circular or an eccentric manner to cut through the pipe.
Lubrication and cutting debris traditionally present operational problems for such cutting tools. Maintaining consistent lubrication at the cutting surface of the blade can be difficult. In the instance of a pipe cutter, for example, the blade may have to be used downhole at great depth or even in a deviated wellbore, making delivery of a desired amount of lubricant difficult. Cutting debris can bind a cutting blade and impede the efficiency of the cutting process.
The invention provides an innovative design for a self-lubricating saw blade assembly that is useful in a circular saw apparatus. An exemplary saw blade assembly is described that incorporates a circular saw cutting blade with one or more associated lubricant discs. In a described embodiment, a single cutting blade is associated with two lubricant discs that are placed located on either axial side of the cutting blade. Also in a described embodiment, the lubricant discs are bonded to the cutting blade.
In described embodiments, the one or more lubricant discs are formed of a rigid material that can be readily abraded and impregnated with a lubricant. In a particular embodiment, the discs are formed of porous PEEK (polyether ether ketone). The lubricant disc may also be non-rigid, absorbent, easily abraded and can be bonded to the cutting blade. Where the lubricant disc is non-rigid, the cutting blade will provide the rigidity for the saw blade assembly. Other embodiments can include one or more lubricating discs and one or more saw blades. The lubricant discs may be bonded to the cutting blade or, alternatively, they may be mechanically coupled to the cutting blade by means of the arbor shaft and a locking nut. Also in particular embodiments, the lubricant discs are provided with debris removal slots that extend radially outwardly from a hub portion that surrounds the center of the disc.
In operation, a circular saw blade assembly constructed in accordance with the present invention is placed into a circular saw tool, and the circular saw tool is operated to rotate the saw blade assembly and bring it into cutting contact with a workpiece being cut. The blade makes an initial cut into the workpiece, and as the blade penetrates deeper into the workpiece, the one or more lubricant discs are brought into contact with the workpiece and apply lubricant proximate the cut being made as the saw blade assembly is rotated. The edges of the one or more lubricant discs will also abrade and erode as the cutting operation continues, permitting the cut to be made deeper into the workpiece while additional lubricant is secreted and applied. In addition, cutting debris created by the saw blade assembly will be received into the debris removal slots of the one or more lubricant discs, thereby removing the debris from the cutting area.
The advantages and further aspects of the invention will be readily appreciated by those of ordinary skill in the art as the same becomes better understood by reference to the following detailed description when considered in conjunction with the accompanying drawings in which like reference characters designate like or similar elements throughout the several figures of the drawing and wherein:
A generally circular lubricant disc 20, 22 is disposed upon each axial side 13, 15 of the blade 12. The discs 20, 22 are preferably affixed to the blade 12 by bonding using a suitable adhesive. Alternatively, the discs 20, 22 are not secured with adhesive to the blade 12 but are instead, mechanically coupled to the blade 12 by the arbor shaft 18 and associated compression fittings, such as a locking nut 23 (see
The lubricant discs 20, 22 each have an outer circumferential edge 24. It is noted that the diameter of the lubricant discs 20, 22 are less than the diameter of the blade 12, and the outer circumference of the lubricant discs 20, 22 are preferably less than the outer circumference provided by the cutting edge 16 of the saw blade 12 to allow a cut to be started before lubrication is applied. In certain embodiments the lubricant discs 20, 22 are provided with debris removal slots 26 that extend from the outer circumference 24 to a central hub 28. Each lubricant disc 20, 22 has a central opening 30 formed within the center of the hub 28. The central openings 30 are aligned with the central opening 14 of the saw blade 12.
As the cutting process continues, the edges 24 of the discs 20, 22 will begin to erode or abrade away. In addition, cutting debris 44 created by the cutting process will be captured and accumulated within the debris removal slots 26, as
The invention has been described herein using an exemplary saw blade assembly 10 having a single saw blade 12 and two lubricant discs 20, 22. Those of skill in the art will understand that variations of the invention can be made using the principles described herein. For example, multi-layer blade assemblies can be formed of a plurality of cutting blades and lubricant discs arranged in a sandwich structure. Also, a given saw blade assembly might include discs within the sandwich structure having other compositions and functions. For example, a disc might have a brush edge that is used to help brush debris away from the cut being made. Other discs might serve a reinforcing function.
The foregoing description is directed to particular embodiments of the present invention for the purpose of illustration and explanation. It will be apparent, however, to one skilled in the art that many modifications and changes to the embodiment set forth above are possible without departing from the scope and the spirit of the invention.
