Laser-assisted cutting method

Abstract

The present invention provides a method for cutting polymer material or other materials by separating the material along a line of controlled failure through the application of mechanical force in combination with laser light to break molecular bonds holding the material together along the line of controlled failure. The method includes the use of a generally broad wedge-shaped blade having planar lower and upper surfaces which converge toward each other to terminate along a leading edge. The blade is generally hollow with a cavity for passing optical fibers carrying laser light to a transparent window attached to the leading edge of the blade. Laser light passes through the window and is directed to a line of controlled failure in the material being cut to break the molecular bonds and locally weaken the material while mechanical force is applied to the blade to separate the material and advance the line of controlled failure into the material thereby separating a slice of the material.

Description

[0001] This is a divisional application of application Ser. No. 09 / 545,663filed Apr. 7, 2000, which is a continuation of application Ser. No. 09 / 009,908filed Jan. 21, 1998. This application is related to application Ser. No. 09 / 545,444 filed Apr. 7, 2000, U.S. Pat. No. 6,294,757.[0002] The present invention relates generally to a method for cutting or machining polymer material, 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.[0003] 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 ve...

AI Technical Summary

Benefits of technology

[0016] The present invention is directed to improving conventional polymer material-cutting techniques such as those employing a wedge-shaped blade that operates to separate the material (e.g., wood) into separate pieces. Contrary to popular thought, wood-cutting (e.g., to produce thin wood sheets) does not use the so-called cutting edge of the blade --except at initial entry of the blade into the polymer material. When the separation of the wood begins after entry, the pushing forces imparted on the wood by the surfaces of the blade perform the cutting and separation by leveraging those forces ahead of the cutting edge to cause natural fracturing or induce failure of the material at its naturally weakest points. The leading edge of the blade is actually disposed from the line of separation of the wood. If some of the molecular bonds of the wood at a controlled line of separation are broken by a laser and the material is weakened, the forces needed to drive the wood apart are reduced and surfaces can be separated more accurately. This is the function of the present invention.

[0024] If blade 2 remains stationary after a forward thrust into block 50 without assistance of the laser, the line of failure 65 tends to move away from leading edge 15 until the applied forces are balanced by the binding force of the material's fibers at the line of failure 65. Without the assistance of the laser, the fibers in the material would take a finite time (fractions of a second to minutes) to part after a suitable force is applied because of the "creep" properties of natural polymers like wood. Fiber separation (without weakening of the material by a laser) is more even and accurate if blade 2 is pushed slowly into the wood and conversely, it can be rough and inaccurate if blade 2 is pushed into the wood quickly. The use of the laser to assist blade 2 as it moves through the material increases both the speed and the accuracy with which blade 2 can cut through the material. This also provides an improved finish on both surfaces resulting from the cut.

[0027] The laser light 60 is directed onto wood block 50 along the line of controlled failure 65 where the wood is still joined by the strength of its molecular bonds. The laser light breaks molecular bonds of the wood along a line of controlled failure 65 where slice 55 and block 50 are still joined such that a well defined and accurate separation takes place in front of blade 2. Separation of the wood surfaces takes place well in front of the blade and not by contact between the blade and the line of controlled failure. The open geometry between the leading edge of the blade and the line of controlled failure allows the blade to direct the laser light along the line of controlled failure in front of the blade. The distance between the leading edge of the blade and the line of controlled failure remains essentially the same as the block of wood is moved past the blade.

[0028] The energy required by the laser to weaken the material by breaking some molecular bonds is less than the additional energy required to generate sufficient mechanical force for the blade to separate the materials'surfaces without the assistance of the laser. The laser light reduces the total energy required to cut the material to a given depth while creating a more accurate and less damaging cut.

[0029] The present invention reduces the power required to cut wood and other materials capable of being cut or machined by similar techniques, reduces the time necessary to cut a given area of wood surface, eliminates pre-cut preparation and increases accuracy and cleanliness of the cut.

Problems solved by technology

However, the prior art devices use traditional mechanical cutting methods or use the thermal heat from a laser to decompose and vaporize, or burn 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 burns, or in cuts which lack desired accuracy.

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.

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