Electric heating – Metal heating – By arc
Reexamination Certificate
2000-04-07
2001-09-25
Heinrich, Samuel M. (Department: 1725)
Electric heating
Metal heating
By arc
C219S121730
Reexamination Certificate
active
06294757
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates generally to a method for cutting or machining wood, and more specifically to a method for cutting wood and other materials capable of being cut or machined by similar techniques, using a blade with the assistance of a laser.
A number of methods and devices for cutting wood and similar materials are known in the prior art Prior Art devices for cutting wood include knives, chisels, saw-teeth, machining bits and tools, and lasers. Examples of prior art cutting methods and devices include: Apparatus for dividing wood, U.S. Pat. No. 5,179,883; Veneer Slicer Machine, U.S. Pat. No. 3,796,243; Wood Slicer Machine, U.S. Pat. No. 3,783,917; Process for slicing veneer, U.S. Pat. No. 4,362,197; Method and apparatus for cutting boards using opposing convergent laser light, U.S. Pat. No. 5,578,229; Machine tool with a laser beam cutting device, U.S. Pat. No. 4,335,296; Laser assisted saw device, U.S. Pat. No. 4,469,931; Laser cutting process, U.S. Pat. No. 5,374,803; Laser beam machine and laser beam machining method, U.S. Pat. No. 5,582,749; Laser deep cutting process, U.S. Pat. No. 3,965,328.
However, the prior art devices use traditional mechanical cutting methods or use the thermal heat from a laser to decompose and vaporize, or bum a cut into, the material. Use of prior art devices often results in material loss from the width of the cutting device, in damage to the surface from bums, or in cuts which lack desired accuracy. Products made from wood, and other materials capable of being cut or machined by similar cutting techniques, can be fabricated more efficiently and with less material loss when the width of the cut, or kerf, is reduced. Further efficiency and increased product value is gained by reducing damage to separated material surfaces by improving cut accuracy which results in a better finish after the cutting process.
Although increased cut accuracy and cutting ease can be achieved by preparing wood or similar material such as by steaming or soaking the material in a liquid bath (for slicing or peeling veneers), or by drying the wood before planing (to increase surface smoothness), these and other pre-cut preparation techniques are expensive, time consuming, and may cause undesirable and irreversible changes to the body of the material beyond the specific area of the material being cut or machined.
SUMMARY OF THE INVENTION
The present invention provides a method for cutting wood, or other materials capable of being cut or machined using similar methods, by separating the material along a line of controlled local failure in the material through the application of mechanical force as imparted by a wedge (e.g., knife blade) in combination with a laser beam to break molecular bonds that naturally hold the material together at the line of controlled failure.
Advantages of the present invention include efficient cuts without damage to the wood or other material, elimination of expensive or time-consuming preparation techniques, reduction in the loss of material from the width of the cutting device, improved accuracy of the cut, and improved quality of the separated surfaces on each side of the cut.
The present invention uses laser light to assist a mechanical cutting blade by locally weakening the material along the line of controlled failure. The laser light breaks molecular bonds at the line of controlled failure within the material being cut while the blade separates the material and advances the line of controlled failure in front of the blade to create the cut and a continuing path for the blade. The laser significantly reduces the force required to separate the material along the line of controlled failure and induces material failure without significant damage to material adjacent to the cut.
In a preferred embodiment of the invention, the leading edge of a wedge-shape mechanical cutting blade contains a window made of a material that transmits laser light. Light from a laser reaches the window through optical fibers connected to, and contained in the body of, the blade. During a cutting operation laser light from the laser unit is directed through a window mounted at the leading edge of the blade, and into the region in front of the blade where a line of controlled failure is induced in the material by the laser light. The laser light breaks the molecular bonds in the wood to assist the cutting process at the line of controlled failure.
Further, while a conventional blade separates material in the path of the blade along fault lines or defects in the material which do not follow straight lines in front of the blade, the laser-assist of the present invention controls the path of failure and thereby avoids meandering cuts and inaccurate surface finishes that result from natural fractures and defects. The present invention is capable of cutting very thin sections of material in one pass more accurately and efficiently than prior art devices because there is essentially no material loss from the cut.
The laser reduces the normal mechanical force required to cut material, thereby reducing the power and time required to cut the material. The present invention can therefore increase production over prior art devices while providing improvements in the quality and accuracy of the cut surfaces without prior special preparation of the material.
A further understanding of the nature and advantages of the invention may be realized by reference to the remaining portions of the specification and the drawings.
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Heinrich Samuel M.
Townsend and Townsend / and Crew LLP
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