Patent Application
20230311273
This disclosure generally relates to apparatus for abrasive removal of surface finishes and more particularly relates to apparatus and methods for surface treatment using low pressure abrasion with a dry, chemically inert abrasive.
Stripping of finishes from the surface of wood and other materials is a familiar task to those who refinish and refurbish furniture and household items. Conventional solutions to this problem have included the use of toxic solvents and other chemicals, applied to the coated item by painting or spraying or, in some cases, by immersion, followed by painstaking scraping and probing with various types of hand tools.
More recently, the surface stripping problem has been addressed using caustic abrasives such as soda, mixed with water and blasted against the surface at high pressures. While this method has proved successful for removing finishes on metal, its use for wooden surfaces is highly unsatisfactory. Following blasting, for example, the caustic chemical must be fully removed from the wood surface, or at least neutralized, to prevent ongoing damage. The application of water causes the wood to expand and can easily damage the surface, so that subsequent refinishing is compromised and subject to undesirable chemical reactions, even where the surface has been thoroughly cleaned.
The high pressures used, as well as use of chemical agents, and related side-effects of high pressure blasting with caustic substances, can make conventional solutions unacceptable for renovation of delicate wood veneers having highly intricate carvings, typical of many antique furniture and structures. Moreover, abrasive blasting must be done under carefully controlled conditions, due to dust and other hazards of high-pressure abrasive delivery and complicated by environmental measures needed to dispose of the spent abrasive chemicals. Antique surfaces such as those that can be found in built-in fireplaces and mantles, kitchen cabinetry, and other structures, must often be physically removed and treated outdoors or processed in a separate facility, risking damage to antique woodwork that can be irreplaceable and, in some cases, is considered priceless.
Thus, there is a need for surface treatment apparatus and methods that can remove surface finishes without damage, even allowing in situ stripping and refinishing for delicate antique woodwork.
It is an object of the present disclosure to advance the art of surface treatment, particularly for surfaces of wood and other delicate materials.
It is a feature of the present disclosure that it provides a solution to the surface removal problem that is nontoxic, works at relatively low pressures, and leaves no chemical or caustic residue that would obstruct subsequent refinishing processes. In particular, the nozzle that is used for application of the surface removal apparatus has simple construction and can be readily formed using additive or “3D printing” fabrication techniques.
These and other aspects, objects, features and advantages of the present disclosure will be more clearly understood and appreciated from a review of the following detailed description of the preferred embodiments and any appended claims, and by reference to the accompanying drawings.
According to an aspect of the present disclosure, there is provided an apparatus for treatment of a surface comprising:
While the specification concludes with claims particularly pointing out and distinctly claiming the subject matter of the present disclosure, it is believed that the invention will be better understood from the following description when taken in conjunction with the accompanying drawings, wherein:
The present description is directed in particular to elements forming part of, or cooperating more directly with, apparatus in accordance with the invention. It is to be understood that elements not specifically shown or described may take various forms well known to those skilled in the art.
Where they are used, the terms “first”, “second”, and so on, do not necessarily denote any ordinal, sequential, or priority relation, but are simply used to more clearly distinguish one element or set of elements from another, unless specified otherwise.
As used herein, the term “energizable” relates to a device or set of components that perform an indicated function upon receiving power and, optionally, upon receiving an enabling signal.
The term “actuable” has its conventional meaning, relating to a device or component that is capable of effecting an action in response to a stimulus, such as in response to an electrical signal, for example.
The term “fluid” in the context of the present disclosure has its meaning in physics, relating to a substance that is capable of flow, and more particularly to an aggregate comprising air or other gas mixed with a particulate material, wherein the particulate is fine enough in size and weight to be suspended within a gaseous medium, to allow controlled flow from a source to a target surface that is being treated. Two components can be considered to be “in fluid communication” when such a fluid can be controllably conveyed, such as under pressure or due to gravity, from one component to the other with negligible loss of fluid content. The phrases “fluid flow” and “gas flow” can be considered equivalent for the purposes of the present disclosure.
Adhesive particles are graded according to particle size, under various industry standards, such as those established by the Federation of European Producers of Abrasives (Paris, France), for example. Grit sizes are expressed as numbers that generally represent number of particles that can be fitted or distributed over a given area, often without any specified measurement units designated (e.g. 80 grit, 100 grit, 1200 grit, etc.) As with conventional sand-paper grades, for example, mesh size value is inversely related to abrasive particulate size. Thus, the higher the mesh (sieve) size value, the smaller the maximum particle size that can be sifted through the mesh. Abrasive powder is typically graded by average size, such that a distribution of particulate has at least 50% of the powder at or near the rated or nominal size, such as within +/−10% of the nominal mean particulate size for a given grit grade.
The apparatus and method of the Applicant address the need for an improved solution to the problem of surface treatment for removing finish treatments to various surfaces, particularly applicable to varnished wood surfaces such as those commonly found in antique furniture, built-in woodwork, and cabinetry. The Applicant's solution to the problem offers a number of advantages over previous attempts to address this problem, including:
With appropriate nozzle and protective apparatus, the Applicant's solution can even allow in situ refinishing of varnished surfaces in some cases, obviating the need to disassemble highly ornate or old woodwork in order to provide re-surfacing treatment outside of a dwelling, for example.
The schematic diagram of
Using the
The abrasive powder 24 used by apparatus 10 of
The abrasive glass powder may be recycled glass; however, manufactured abrasive glass powder is typically not fabricated from recycled materials. One supplier of suitable abrasive is Strategic Materials, Inc., Houston, TX. A commercially available product of this supplier is 3-Mix-Processed Glass Abrasive, including a product named New Age Blast Media®.
Because the glass powder does not react with any known surface finishing material, it can be recycled easily for re-use. Spent abrasive powder can be swept or vacuumed from the floor and directly fed back into the holding tank, without requiring other treatment. Alternately, spent abrasive can be sifted through a sieve for cleaning before re-use.
Although it can present a dust hazard until the particulate settles, spent abrasive glass powder is chemically non-toxic and can be disposed of without requiring special treatment or handling.
The delivery pressure at nozzle 30 in the
Compressor 12 or other gas sources typically provide pressure in the 120-150 psi range. Regulator 16 then reduces this source pressure at the holding tank 20. The delivery pressure used at the output of the Applicant's surface treatment apparatus 10 is generally well below levels appropriate for trigger gun devices, which typically require a minimum of at least 70 or 80 psi.
By using the holding tank 20 and regulator 16 to control particulate delivery, the output pressure of the system can be well-controlled, kept to within levels well below those used for conventional refinishing. This can help to reduce waste and can offer benefits in reduced energy requirements.
The delivery hose 22 can be plastic, nylon, or other type of material capable of handling the needed pressure levels.
Because the system controls and regulates internal air pressure, abrasive powder is ejected at relatively low pressures; there is no need for high-pressure trigger gun devices, such as those used for soda blasting and sand-blasting systems. Instead, the nozzle design for low-pressure delivery of inert abrasive glass powder can use mechanisms and materials that would be unsuitable for conventional surface-adhesive delivery equipment.
Referring to
Nozzle 30 can be formed of plastic, nylon, or other type of synthetic material. According to an embodiment of the present disclosure, nozzle 30 is formed by additive manufacturing methods, using the type of fabrication commonly referred to as “3D printing”. Nozzle 30 can be formed from metal or from a variety of polymer materials, including nylon and other polyamides, plastic, and other synthetic materials.
Insert 34 can be formed from a hardened metal component, of a metal material that is suited to handling abrasive flow without significant deterioration and wear to the orifice opening over time. Exemplary materials for insert 34 can include stainless steel, tungsten steel, and carbide steel, or other type of hardened steel for example. Orifice 38 size can be in the range from about 3/32 in. to 5/32 in. For example, a ⅛ in. orifice 38 can be suitable.
Hardened metal includes metals that are heat-treated following casting or initial forming to shape as a finished piece. Typical heat-treated steel can have a hardness in the range from 49-63 HRC (Rockwell scale), for example.
Insert 34 can be affixed within feeder tube 36 in a number of ways, including the use of adhesives or by press-fitting, heat-insertion, sonic welding, pressing, threading, and insert molding, for example.
Feeder tube 36 itself can be formed from a polymer. The Applicants have found that polymers such as ABS and various other types of plastics, nylon, and reinforced composite materials that include plastics and other polymers, such as fiberglass, are advantaged over metal components due to low thermal conductivity. The ability of polymer materials to absorb heat levels from the propelled abrasive materials under pressure allows the operator to operate the nozzle equipment without concern for heat protection. This permits the operator to wear light nylon gloves, nitrile or neoprene gloves, vinyl gloves, or protective gloves of other light, plastic material during blasting.
Conventional fittings, such as hose clamps, worm-gear clamps, and other low-pressure-compatible fittings can be used for fastening hose 22 to nozzle 30.
A variety of fixtures and attachments can be added to the basic surface treatment apparatus 10 shown in
The schematic diagram of
The functions of holding tank 20 and compressed gas source 90 can be combined, such as by providing a pressurized holding tank, pressurized prior to use or fabricated and sold as a pressurized item.
According to an alternate embodiment, as shown in the schematic diagram of
A supply reservoir 114, within or coupled to housing 56, can be filled by the user prior to use of apparatus 100 and can be refilled as needed during the stripping process. Reservoir 114 is in fluid communication with compressor 112 and associated regulator 16 and other mixing components and tubing and can provide a gravity-fed abrasive treatment system. The regulator can be incorporated as part of compressor 112, if needed; alternately, compressor 112 may be rated to provide a suitable range of pressure levels without the need for a separate regulator component.
Portable surface treatment apparatus 100 can have an optional sensor 120 for sensing abrasive level in supply reservoir 114 and an optional indicator 122 that is energized to indicate a suitable supply level, above a predetermined threshold, or low supply level, below the threshold. For example, indicator 122 can flash on and off to indicate the need for replenishing the reservoir 114. An optional control 124 can be provided to allow adjustment of the output pressure, such as to adjust pressure for different materials being treated. Alternately, the effective nozzle 30 orifice opening can be adjusted, such as by rotating a control at the nozzle 30 output.
Advantageously, the apparatus and method of the present disclosure can be used to remove surface finishes from highly ornate carved and veneer surfaces found on antique furniture, decorative trim and molding such as cornices, and household items. Because it operates using a dry abrasive that is chemically inert and nontoxic, the approach of the present disclosure is particularly suitable for treatment of wood as a preparatory step to subsequent refinishing. The method of the Applicants operates at low pressure levels, well below the air pressure needed within a standard automobile tire, alleviating concerns with use of compressed air equipment. The abrasive glass powder can be recycled numerous times and can be disposed of without concerns for environmental toxicity.
An apparatus for treatment of a surface has: a source of gas pressure; a holding tank configured to mix pressurized gas from the source with an abrasive glass powder, wherein the powder has a mean particulate size of 210 microns or less; a regulator in fluid communication with the holding tank and configured to reduce output pressure from the holding tank to 20 psi or lower; and a nozzle that is in fluid connection with the holding tank output. The nozzle has: (i) a shutoff valve or other valve type; (ii) a feeder tube fitted to the valve and formed of a polymer material; (iii) a hardened metal insert fitted into an end of the feeder tube and orificed to direct the compressed gas and abrasive glass powder to the surface. The apparatus can have a transparent hood with a vacuum attachment configured to remove spent abrasive powder from the surface. The output pressure can be further reduced, such as to no more than 17 psi.
The invention has been described in detail with particular reference to certain preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the scope of the invention as described above, and as noted in the appended claims, by a person of ordinary skill in the art without departing from the scope of the invention.
This application claims the benefit of U.S. Provisional application Ser. No. 63/324,786, provisionally filed on Mar. 29, 2022 entitled “APPARATUS FOR ABRASIVE SURFACE TREATMENT” in the name of David Ogle, incorporated herein in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| 63324786 | Mar 2022 | US |
