Cutting torch and associated methods

Metal treatment – Process of modifying or maintaining internal physical... – Chemical-heat removing or burning of metal

Reexamination Certificate

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Details

C266S048000

Reexamination Certificate

active

06183569

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally relates to an apparatus and method for cutting target material. The present invention more particularly relates to an apparatus and method for cutting target material of a substantial thickness using a thermite based charge.
2. Description of the Prior Art
A number of devices for cutting materials of a substantial thickness are known in the art. Many of these devices employ explosive shaped charges which deliver energy to the surface of a material in the form of a high pressure, high velocity shock front. The conical or “V” shaped charge, for example, explodes and focuses cutting energy onto the surface of the material to be cut. A primary disadvantage of explosive shaped charges is that they generate excessive noise and debris upon detonation. This noise and debris can pose potentially serious health and safety hazards to someone using a cutting device which employs conventional shaped charge explosives.
Thermite-based cutting devices which employ a cutting flame produce virtually no extended shock wave and generate relatively little over pressure. Thermite-based cutting devices do not present the same health and safety hazards which are attendant upon explosive shape charge cutting devices.
U.S. Pat. No. 2,587,243 discloses an apparatus for producing a gaseous penetrating jet for cutting materials or objects. This patent uses a chemical charge which, when detonated, ruptures a means interposed along the path of the generated high velocity gases. The means converges upon rupture and causes a material placed beneath the apparatus to be cut by the resultant high velocity gas explosion.
U.S. Pat. No. 4,693,181 discloses a linear cutting charge device including an explosive mass formed in the shape of a bar. Detonation of the charge in this patent is disclosed as stating that it compresses a metal liner and converts the metal liner into an outwardly projected slug of metal, the shape of which is dependent upon the shape of a cavity of the device. It is this outwardly projected slug which penetrates the work surface of a material which is cut or deformed by the detonation and subsequent penetration.
U.S. Pat. No. 4,815,384 discloses a device with a housing for use with joinable or interconnectable cutting charges. The stated purpose of this patent is to avoid formation of a saw-tooth cutting profile on a target work surface acted upon by the device discussed in the patent.
What has not been disclosed in the prior art, however, is use of a thermitebased apparatus for directing or focusing a cutting flame derived from the activation of a thermite charge for the purpose of cutting substantially thick material such as steel plates and bars, for example. In addition, the prior art has not provided a practical solution for effecting an extended, linear cut in a piece of material. The prior art also has not sufficiently addressed concerns related to the health and safety of a user using an explosive shape charge apparatus to create high velocity explosions to cut material. As a result, the prior art has also not adequately considered use of a thermite-based cutting apparatus to alleviate hazards associated with debris, noise and pressure waves generated from using explosive charges to cut material having a substantial thickness.
In spite of the foregoing known apparatus and methods for cutting material, there remains a real and substantial need for an apparatus for cutting material which employs a thermite-based charge to ensure a safe and efficient cutting action.
SUMMARY OF THE INVENTION
The apparatus for cutting material of the present invention includes at least one housing having an inner cavity and an elongated nozzle extending from the inner cavity to the exterior of the housing. An energetic material, such as a thermite charge, is contained within the inner cavity to provide the apparatus with a source for a cutting flame, or high temperature, high velocity jet. An activating device, such as an igniter, is coupled to the thermite charge to develop a cutting flame from the inner cavity when desired by a user. In addition, more than one such cutting apparatus may be joined or “ganged” together to form a unitary cutting apparatus which is capable of performing an extended, linear cutting action on a target material.
In another aspect of the present invention, opposed cutting apparatus are provided for cutting differently shaped material, such as steel bars and bar stock, of various diameters. In this embodiment, the opposing cutting apparatus provide opposing cutting flames which act against at least two sides or portions of a target material. In addition, improved efficiency is achieved by providing better control of burn rate to match the absorption and ablation properties of the target material. Total cutting time is also decreased. Energy losses which normally occur due to thermal conduction of energy from the cutting zone of the target material to other portions of the target material are reduced.
The present invention also discloses a method for cutting a target material comprising the steps of providing at least one housing with an inner cavity and an elongated nozzle in communication with the inner cavity extending to the exterior of the housing. The nozzle is structured to be generally adjacent to a target surface of the target material to be cut. A distance or “standoff” is provided between the end of the nozzle which directs the cutting flame onto the surface of the target material. The method also employs an energy source for generating a high temperature, high velocity cutting flame or jet, such as by employing a thermite charge. The nozzle is then placed an appropriate distance or “standoff” from the target material. The thermite charge is then activated and a cutting flame is generated from the charge positioned in the inner cavity. In another aspect of the method of the present invention, more than one cutting apparatus may be joined or “ganged together” to effect an extended, linear cutting action.
The cutting apparatus of the present invention also provides a safer and more efficient apparatus and method for producing a cut in a portion of a target material having substantially uniform thickness. The cutting apparatus provides an elongated nozzle to accommodate varying thicknesses in the cutting region of different target materials. In the “ganged together” arrangement, the present invention offers a method for effecting substantially longer cuts by joining together more than one apparatus to provide a substantially sequential cutting action. The present invention also provides a formable, and separately storable, thermite powder charge for providing an energy source for generating a cutting flame which produces the cutting action of the apparatus.
It is an object of the present invention to provide a material cutting apparatus having an elongated nozzle structured to be a controlled distance or “standoff” from the surface of a target material.
It is an object of the present invention to provide a safe and economical apparatus for cutting thick materials such as metals, plastics, and ceramics.
It is an object of the present invention to provide a thermite-based cutting apparatus employing a formable thermite powder charge as a source for generating a cutting flame.
It is an object of the present invention to provide an apparatus for cutting various material thicknesses by establishing a nozzle standoff, nozzle cross-section, thermite burn rate, and burn duration.
It is an additional object of the present invention to provide an apparatus capable of effecting an extended, linear cutting action along the surface of the target material to be cut.
It is an object of this invention to maximize cutting efficiency by providing impingement of at least two cutting flames on opposing sides of a target material.
It is a further object of the present invention to provide a cutting apparatus which is capable of cutting shaped material, such as steel bars.
It is a further object of the present

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