Patent Application
20140072766
The present invention relates to simulated wood appearances on items and products, and more particularly relates to debossing apparatus and methods for creating depth-changing, non-repeating patterns that simulate a wood grain appearance on a sheet material surface such as steel or other metals.
In various applications and uses ranging from park bench equipment, restaurant chairs, and premium healthcare seating, a preferred material is tubular or sheet metal steel. The use of metal or steel provides durability and maintenance-free use. However, there is a desire to soften the cold, formal qualities of metal and steel objects by enhancing or altering the external appearance of the particular item or object. For example, it may be desirable to have the appearance or texture of wood on the exposed surfaces. To further enhance the aesthetic appeal with a visually decorative and pleasing effect, it would be desirable to stain the simulated wood appearance with a wood-like stain such as cherry, walnut or rosewood.
Various techniques and processes have been developed for simulating a wood grain appearance on metal and steel items and objects that are used in both private and public settings and environments. For example, one technique is to laminate the metal or steel object with a vinyl film having a wood grain pattern printed thereon. Another process involves directly printing the wood grain pattern on the surface of the metal that is then formed into an object such as a restaurant bench or furniture item. However, such printed surfaces are susceptible to being marred by scratch and scuff marks and their restoration is difficult and expensive. Another technique is to manually stain the steel, metal strip or sheet in order to give it the striated appearance of wood grain, but this technique requires considerable artistic skill and is also quite expensive.
Drums have been used to produce wood grain patterns in metal sheets. However, the patterns created by such drums have uniform depths that do not provide an optimal wood grain appearance when the surface is colored and stained. Such drums have been used in combination with opposing drums that are aligned with each other at uniform separation distances. However, it has been found that such an arrangement does not provide a realistic wood grain appearance because the pattern repeats itself upon each revolution of the drum rather than providing a more natural-looking non-repeating pattern.
The present invention provides apparatus and methods utilizing a debossing drum for creating a wood grain appearance on strip materials such as a metal or steel sheet. The wood grain appearance comprises a depth-changing pattern, and may be non-repeating as a result of movement of the strip material transversely across the debossing drum as the strip material is fed in a length-wise direction. As more fully described below, rather than repeating the identical wood grain pattern upon each rotation of the debossing drum, the transverse movement of the work piece results in non-repeating wood grain patterns. The debossing drum has an outer surface covered with upraised protrusions or markings in the form of a pattern such as wood grain that is arranged in a depth-changing manner. In accordance with embodiments of the present invention, the upraised protrusions or markings on the drum or roller may vary in depth transversely from the center of the drum outwards. The depth variation may enhance the markings on certain areas such as the cathedral portion of a wood grain pattern, while minimizing the depth and relevance of the ticking of the wood grain pattern. The strip material or work piece may move back and forth in relation to the debossing drum, transverse to the linear feed of the strip material, in order to create a non-repeating pattern on the strip material through contact of the drum outer surface against the surface of the strip material.
After the strip material is fed through the debossing drum, a series of steps or processes may then follow to complete the process of creating a wood grain appearance on the strip material. In certain embodiments, the patterned strip material may be formed into a round tube shape by rolling and then welding the seam. The formed tube may be used as round tubing, or may be further formed by, e.g., sending it through a head reshaping tool to produce square, triangular, rectangular, D-shaped or other desired cross-sectional forms. The various cross-sections may then be cut to length and welded to complete the fabrication of the desired work piece, such as a chair of a desired configuration or any other item that uses wood as its main construction medium. The debossed material with its wood grain pattern may be cut into two dimensional shapes to later be fabricated into various three dimensional finished products.
In certain embodiments, after fabrication is complete, the work piece may be washed, e.g., in a bath of an alkaline solution, rinsed, washed in another bath, e.g., iron phosphate, and then dried in a heater to prepare the work piece for resin powder coating. Colored resin powder may then be electrostatically applied to the fabricated assemblies. The assemblies may then be heated to cure the resin and to bake the powder onto the assemblies. Thin milled resin powder may be used so that the debossing is not filled by the resin coating. The thin milled powder may determine the final color of the product. Stain, such as an oil-based stain, may be applied to the product, and then wiped off before it dries. The stain that remains in the depressed debossed areas contrasts with the base coat color creating a wood grain appearance. Due to the depth differences that are present in the pattern transversely across the metal sheets, the stain that settles into the debossed areas will vary in contrast, with deeper depressions having darker appearances. Essentially no artistic skills are required during the staining process to provide a realistic wood grain appearance to the metal surface.
An aspect of the present invention is to provide an apparatus for making a wood grain appearance on sheet material comprising a debossing assembly for imparting a non-repeating wood grain pattern on the sheet material, wherein the debossing assembly comprises a debossing drum and an opposing drum, and at least one of the debossing drum and opposing drum are supported by at least one height-adjustable piston that moves the debossing and opposing drums toward or away from each other to a position in which opposing surfaces of the debossing and opposing drum are unequally spaced from each other on one longitudinal end of the debossing and opposing drums in comparison with another longitudinal end of the debossing and opposing drums.
Another aspect of the present invention is to provide an apparatus for making a wood grain appearance on sheet material comprising a debossing drum for imparting a depth-changing wood grain pattern on the sheet material, wherein the debossing drum comprises protrusions extending from a generally cylindrical surface of the debossing drum, and the protrusions have different depths in different regions along the transverse length of the debossing drum.
A further aspect of the present invention is to provide a method of making a wood grain appearance on sheet material comprising feeding the sheet material through a debossing assembly to thereby impart a non-repeating wood grain pattern on the sheet material, wherein the debossing assembly moves the sheet material in a transverse direction as the sheet material is fed through the debossing assembly.
Another aspect of the present invention is to provide a method of making a wood grain appearance on sheet material comprising contacting the sheet material with a debossing drum to thereby impart a depth-changing wood grain pattern on the sheet material, wherein the debossing drum comprises protrusions extending from a generally cylindrical surface of the debossing drum, and the protrusions have different depths in different regions along the transverse length of the debossing drum.
A further aspect of the present invention is to provide a debossed sheet material comprising a non-repeating and depth-changing wood grain pattern.
These and other aspects of the present invention will be more apparent from the following description.
As shown in
A wood grain pattern is arranged on the external surface 20 of the debossing drum 18 comprising upraised or projecting protrusions, ridges or bumps 22. The protrusions 22 may be disposed parallel, perpendicular or at various angles to each other, and may be used to produce a non-repeating debossed pattern. In certain embodiments, the protrusions 22 cover the surface 20, and are arranged on the external surface with varying depths, e.g., with the depths varying transversely from the center of the debossing drum 18 outward in a direction parallel with the rotational axis of the drum 18. The sheet material 16 may be fed or conveyed by drums or rollers serially arranged on a conveyor line or assembly in a linear direction indicated by arrow 38 in
As shown in
The undebossed surface of the sheet material 16 enters the debossing assembly 50 and the debossed surface 17 of the sheet material 16 emerges from the debossing assembly 50 with depressions or valleys 21 having non-uniform depths which make up a debossed wood grain pattern 12. The sheet material 16 then enters an exit straightener 66 where it passes through opposed rolls 68 and is then rewound into coil form 72 by a strip rewinder 70 onto a take-up roller or spool 74. The strip rewinder 70 includes a driven take-up roller 74 that pulls the sheet material through the debossing assembly 50. The sheet material is straightened by pulling the sheet material past the un-driven debossing drum 18 and opposing drum 52 with the take-up roller 74.
In accordance with embodiments of the present invention, the hydraulic servo/pressure controllers 55A and 55B and their hydraulic cylinders and pistons 56A and 56B are used to move the sheet material 16 transversely with respect to the debossing drum 18. Such transverse movement of the sheet material 16 is illustrated in
The transverse movement of the sheet material 16 is accomplished by controlling the hydraulic pressure applied to each of the hydraulic cylinders and pistons 56A and 56B. The hydraulic servo/pressure controllers 55A and 55B are used to adjust the pressure of the hydraulic fluid supplied to their respective hydraulic cylinders and pistons 56A and 56B. When pressure is increased in one of the hydraulic servo/pressure controllers 55A or 55B, the piston of its respective hydraulic cylinder and piston 56A or 56B presses with more force against the lower drum bearing support 67. The resultant increased force pushes or pinches that side of the lower drum 52 toward the debossing drum 18, thereby causing the sheet material to move transversely away from that side of the lower drum 52. The hydraulic servo/pressure controllers 55A and 55B may thus be used to supply differential hydraulic pressures that cause the sheet material 16 to move transversely. If it is desired to maintain the sheet material 16 in a particular transverse position, the pressures supplied by the hydraulic servo/pressure controllers 55A and 55B may be equalized, thereby providing equal pressure on both transverse sides of the lower drum 52.
The particular pressures applied via the hydraulic servo/pressure controllers 55A and 55B may be routinely selected by those skilled in the art. For example, a standard pressure of 1,500 psi may be used, with pressure increases or decreases in a range of from 1 psi to 100 psi for each hydraulic servo/pressure controller, for example, pressure variations of from 2 psi to 10 psi may be suitable to control the transverse movement of the sheet material 16 across the debossing drum 18. A controller, such as a PLC, may be used to adjust the pressures to the hydraulic servo/pressure controllers 55A and 55B. A sensor (not shown), such as a light curtain, may be used to detect the transverse position of the sheet material. The detected position may then be fed to the controller to adjust the pressure applied to the hydraulic servo/pressure controllers 55A and 55B.
Although the hydraulic servo/pressure controllers 55A and 55B, and the hydraulic cylinders and pistons 56A and 56B, shown
As shown in
In accordance with embodiments of the invention, in subsequent coloring and staining operations, the applied stain fills the depressions or valleys and creates a darker appearance in the depressions or valleys that are deeper. For example, in the embodiment shown in
It should be noted, as illustrated in
Steel coil 72 that has been patterned with depressions 21 on its first surface 14 may be rolled into round steel tube 76 and seam welded at 78, e.g., in a tube mill. Some of the steel tube 76 may be used in products in its round form, and the rest of the round tube may be reshaped by a commercially available Turix head reshaping tool or other means to produce other desired tube cross sections, including triangles 80, squares 82, rectangles 84, D-shapes, and any other desired shape in any desired size. The shapes, widths, and lengths are then assembled into the desired configurations such as a chair by cutting, welding, and brazing. Assembly can be facilitated with fixturing and cutouts. The article is now in its final configuration except for the coloring to provide the appearance of the desired species of wood.
In the alkaline solution and iron phosphate bath step, fabricated metal parts are first immersed in a liquid media with high alkalinity that caustically cleans the parts of grease, debris, and other substances that may hinder the quality of the powder coating process. After being rinsed in water, the cleaned surfaces of the fabricated parts then undergo an iron phosphate bath that deposits iron ions onto the fabricated part and creates an amorphous and inert surface ideal for resin powder coating. When finished, the fabricated parts are removed, rinsed, and are dried in a heated space to remove water therefrom.
When the alkaline solution and iron phosphate bath step 24 is complete, the next step is applying a base coat 28. The base color is selected to provide a desired wood appearance. The base color may be selected from the following group to provide the desired wood appearance: beige powder for natural wood appearance, tan powder for oak appearance, burgundy powder for mahogany appearance, medium brown powder for walnut appearance, and any multitudes of various formulations to produce any possible color combination.
A colored resin in powder form may be electrostatically applied to the fabricated parts. The parts are then cured at any suitable temperature, e.g., at a temperature of 380°, to bake the powder onto the fabricated surfaces. The electrostatic coating process applies a mild negative electrical ground charge to the fabricated parts to be finished. The electrostatic spray gun charges the powder finishing material with a positive electrical charge. The material is attracted like a magnet to the fabricated parts which assures a uniform coating application with little or no overspray or fog.
In certain embodiments, the colored resin powder is applied as a coating between 0.002 to 0.003 inches thick. In one embodiment, a thin mill powder may be used which can be applied in an extremely thin coating while still achieving complete uniform coverage. For example, the thin mill powder covers in a layer 0.001 to 0.005 inch thick. The importance of this thickness is that it assures that the debossed material will still have sufficient depth to accept the stain in a later step. This assures that the stain will not be removed from the debossed spaces during the wipe-off process discussed later. The base color of the thin mill powder determines the final color of the fabricated parts. For example, to simulate a natural wood finish use beige resin powder, to simulate an oak wood finish use tan resin powder, for a mahogany appearance use burgundy resin powder, and for a walnut appearance use medium brown resin powder. The color of the finish can be changed by merely changing the base color of the product.
The thin film powder coating formulations may include fillers known in the art. Any such fillers may be made to a smaller particle size to reduce any bumps or texture appearance. The final product may also be ground to a finer particle size. The powder coating may typically be ground to a mean of 40 to 60 microns, and the thin film powders may typically be ground to a mean of 25 to 30 microns.
Electrostatic application of the powder provides for the desired wood grain color in the specific color chosen and gives the sheet material 16 a protective layer for end products such as park benches or restaurant seats. A baking step 32 bakes the electrostatically applied powder onto the first surface 14 of the sheet material 16, e.g., at a temperature of 400° for at least 20 minutes. Filler material ground to size may be used to reduce the volume of resin used in the coating.
The color for the stain in the debossed areas is selected to provide a desired wood appearance. The stain may be selected from the following group to provide the desired contrast in colors: cherry stain for natural wood appearance or for oak appearance, black stain for mahogany appearance or walnut appearance, and any other multitude of various stain applications to produce any possible color combination.
The staining step 31 may be accomplished as follows. First, an oil based stain may be applied to the fabricated part. The stain is then wiped completely off of the fabricated part before drying. The stain that remains in the debossed areas creates the varied wood grain appearance. This appearance is created without the necessity or use of any artistic ability on the part of the workman required to complete this process. A clear coat 33 of protective material such as polyurethane may be applied over the stain coat.
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The present invention provides wood grain appearances on the external surface or surfaces of objects, items, furniture, fixtures, and equipment. The process and apparatus may be used to create a random or non-repeating, depth-changing pattern on the external surface or surfaces of strip material such as steel and metal sheet for simulating a wood grain appearance thereon. The steel and metal sheet can be used for a variety of applications such as metal furniture, restaurant furniture, park furniture, playground equipment, and also for any round or box-shaped tubular segments or lengths that can be formed into anything from handrails and fences to poles and stationary bicycles racks. Other applications may include indoor tables, household fixtures such as outlet covers, baseboard trim, or anywhere else wood is applied. In order to provide a more appealing and aesthetic appearance for blending and corresponding the item or product with its surroundings such as an outdoor park, western-themed restaurant, or assisted living facility, it is desirable to coat, cover, laminate or form on the steel or metal surface a simulated wood grain appearance.
Whereas particular embodiments of this invention have been described above for purposes of illustration, it will be evident to those skilled in the art that numerous variations of the details of the present invention may be made without departing from the invention as defined in the appended claims.
This application claims the benefit of U.S. Provisional Patent Application Ser. No. 61/698,900 filed Sep. 10, 2012, which is incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 61698900 | Sep 2012 | US |
