CA2623913A1

CA2623913A1 - Product having simulated wood grain effect and process for making same

Info

Publication number: CA2623913A1
Application number: CA002623913A
Authority: CA
Inventors: Derek Wickenden
Original assignee: WOODGRAIN TECHNOLOGIES Ltd
Current assignee: WOODGRAIN TECHNOLOGIES Ltd
Priority date: 2008-03-05
Filing date: 2008-03-05
Publication date: 2009-09-05

Abstract

The present invention relates to a simulated wood grain effect applied to an object. The simulated wood grain effect comprises a base coat where the base coat has a paint base selected from the group consisting of waterborne, latex, solvent and oil paints having a textured surface finish. A top paint layer is formed by drawing freshly applied wet paint on the base coat into ridges that emulate the grain ridges found in natural wood.

Description

TITLE: PRODUCT HAVING SIMULATED WOOD GRAIN EFFECT AND
PROCESS FOR MAKING SAME

FIELD OF THE INVENTION

The present invention relates generally to products having a simulated wood grain effect applied to their surface and a process for applying the simulated wood grain effect.
BACKGROUND OF THE INVENTION

It is known that printing wood grain effects using ink on an object can produce a photo realistic pattern. Ink (thin film) finishes embody no texture or feel, are susceptible to ultra violet degradation, display a repeat pattern at every turn of the print roller, and can only be applied to flat surfaces.

Another known method of trying to apply a wood grain effect to object involves first printing a photo realistic wood grain pattern onto a thin foil and then cutting the foil to width and adhering it to the product with adhesive. As this method is an extension of the printing process, it carries with it the detrimental effects inherent with printing. In addition, over time, the substrate, may become problematic, particularly with exterior applications. This method does allow a lightly embossed surface texture, and may be applied to irregularly shaped product. This method requires a considerable inventory of foils with the attendant lead times and costs involved.

Another method employs a raised pattern on a steel forming tool to impress a wood grain pattern into a surface.
Embossing tools come in many forms - rollers, molds etc, but all produce a monochromatic pattern designed to emulate a painted wooden surface rather than a natural wood grain effect. When a mold is used, every piece carries exactly the same grain pattern. When a roller is used, the grain pattern repeats with every turn of the roller. This method is particularly well suited to exterior applications such as doors, which would normally be painted, and can produce very wide sections.

Melamine finishes are normally used on 8 ft x 4 ft sheets.
They consist of a printed grain paper soaked in epoxy and molded to a phenolic backing, or a chip board sheet. This method is well suited to countertops or prefabricated furniture items, but is restricted to those items that can be made from sheet product.

Wood grain finishes can be produced by a number of manual techniques. The quality of effect however, is proportional to the skill of the artisan. In addition, all manual methods are slow and cannot be considered to be commercial in nature.

There is a need for a commercially viable method of applying a textured wood grain effect to objects that overcomes the problems associated with existing methods.

SUMMARY OF THE INVENTION

It is an object of one aspect of the present invention to duplicate to the extent possible on objects the raised grain ridges found on natural wood.

It is another object of an aspect of the present invention to provide a method of applying a simulated wood grain effect to objects.

It is another object of an aspect of the present invention to provide a modified paint for use in the method of applying a simulated wood grain effect to objects.

One aspect of the present invention relates to a simulated wood grain effect applied to an object. The simulated wood grain effect comprises a base coat where the base coat has a paint base selected from the group consisting of waterborne, latex, solvent and oil based paints having a textured surface finish. A top paint layer is formed by drawing freshly applied wet paint on the base coat into ridges that emulate the grain ridges found in natural wood. The top paint layer is preferably of contrasting colour to the base coat.

In accordance with one embodiment of the present invention, the wood grain effect may be produced on an object by drawing a moving ridged plate through freshly applied wet paint on an object, and then drawing the paint into ridges that emulate the grain ridges found in natural wood. The paint ridges settle in a previously applied base coat with a preferred surface finish of 63 to 125 micro inches and preferably of contrasting colour. As the paint ridges thin out, the roughened surface produces half tones of color. In order to generate a non repeating pattern, a pseudo random movement is preferably applied to the ridged plate. This movement may preferably be generated by summing the outputs of multiple hydraulic sine wave generators. When combined, the outputs of the sine wave generators can either negate each other, or accumulate into a large wave, vary continuously, producing a pseudo random hydraulic output. In one embodiment the grain pattern produced may be varied by controlling the frequency of the pseudo random movement controlling the paint spreader. In this manner many species of trees may be emulated. The control of these movements is programmable, allowing for production of specific grain patterns to order.

The method of the present invention is designed to produce a painted wood grain effect at commercially viable speeds and preferably about 80 feet/minute.

In another aspect the present invention provides a modified paint for use in the method of applying a simulated wood grain effect to objects. A commercial available paint base selected from the group consisting of waterborne, latex, solvent and oil based paints is modified with finely ground solid particles, preferably a flour of solid wax particles, in sufficient quantity to produce a surface finish of preferably between 63 and 125 micro inches when the particles are included at 15 grams/liter. The additives in the paint provide a surface texture which mimics the feel of natural wood. Commercially available waterborne paints, modified for this application, may be used in this process.
These non toxic paints have excellent ultra violet blocking characteristics and are suitable for both interior and exterior application without non uniform fading or surface degradation. Use of waterborne paints is eco friendly.

The wood grain effect can be produced to emulate natural unfinished wood. Thisfinish may be stained to produce custom stained colors. A stain with similar ultra violet resistance characteristics as the base coat and top paint layer may be used, particularly for exterior and direct sunlight applications.

A further aspect of the present invention provides a means of simulating the results of different control inputs pre-production without wasting paint, material and machine time.
It would also enable the remote emulation of different species of tree, (hardwoods, softwoods etc) for customer approval. A computer simulator generates a graphic depicting the grain pattern produced with different control inputs.
This permits the design of realistic grain patterns. The control inputs are transferred to the graining machine to produce the desired effect.

Further features of the invention will be described or will become apparent in the course of the following detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

One embodiment of the invention is shown in the drawings, wherein:
Figure 1 is a schematic illustration of a carriage assembly used to apply a simulated wood grain effect to an object in accordance with one embodiment of the present invention.

Figure 2 is a schematic close up view of the operative end of the carriage assembly of Figure 1.

Figure 3 is a schematic front perspective view of a sine wave generator hydraulic master cylinder assembly used with the carriage assembly of Figures 1 and 2;

Figure 4 is a schematic perspective view of three sine wave generator hydraulic master cylinder assemblies of the type shown in Figure 3 each producing a different sine wave and combined to form a hydraulic pseudo random movement generator for use with the carriage assembly of Figure 1 and 2;

Figure 5 illustrates one embodiment showing the sine wave generated by the individual sine wave generator hydraulic master cylinder assemblies of Figure 4 and the resulting sine wave after they are combined to form a hydraulic pseudo random movement generator;

Figure 6 is a schematic bottom view of the hydraulic slave cylinder assembly and ridged plate carrier for the carriage assembly of Figure 1 and 2;

Figure 7A illustrates vertical rotation of the ridged plate carrier shown in Figure 6 at maximum pull;

Figure 7B illustrates vertical rotation of the ridged plate carrier shown in Figure 6 at maximum push;

Figure 8A illustrates axial rotation of the ridged plate carrier shown in Figure 6 at maximum pull;

Figure 8B illustrates axial rotation of the ridged plate carrier shown in Figure 6 at maximum push;

Figure 9A illustrates lateral movement of the ridged plate carrier shown in Figure 6 on counterclockwise rotation;
Figure 9B illustrates lateral movement of the ridged plate carrier shown in Figure 6 on clockwise rotation;

Figure 10 illustrates one embodiment of a pattern applied to a ridged spreader plate attached to the ridged plate carrier of Figure 6;

Figure 11 illustrates the simulated wood grain effect applied to an object using the ridged spreader plate of Figure 1 and the carriage assembly of Figures 1 and 2.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Figures 1 and 2 show schematically one embodiment of a carriage assembly, generally indicated at 1, designed to apply a simulated wood grain effect 50 (see Figure 11) to the surface of an object in accordance with the present invention. The carriage assembly 1 has a longitudinal support surface 2 for supporting an object 3 to which the simulated wood grain effect is to be applied mounted on a frame 4. In Figures 1 and 2 the object 3 to which the simulated wood grain effect is to be applied is an elongated PVC extrusion having a flat top surface 5. The present invention may apply a simulated wood grain effect to objects having different shapes, sizes, materials of construction and applications and the present invention is not intended to be restricted to applying a simulated wood grain effect to objects having any particular shape, size, material of construction or application. In Figures 1 and 2 a pusher bar 6 is designed to push the object 3 along the support surface 2 of the carriage assembly 1. In the embodiment illustrated the pusher bar 6 is inserted into a slot 7 in the support surface 2 and pulled along said slot 7 by chain drive 8 (see Figure 2).

The surface 5 of the object 3 to which the wood grain effect preferably has had a base coat of paint applied in the desired colour and tone then has a fresh coat (or grain coat) preferably of a contrasting colour, applied before being pushed along the carriage assembly. Alternatively the fresh coat of paint can be applied as the object is pushed along the carriage assembly and before the means for creating the wood grain effect.

Paint formulation and performance is a factor in producing a realistic wood grain effect particularly in being able to produce half tones of color. The commercially available paint bases, waterborne, latex, solvent and oil based paints, may be used when modified to produce the surface finish required. Each paint has its own performance and cost characteristics. Selection of the base paint to be used is application specific, dictated by the performance requirements of the finished product.

In order to produce a wood grain effect that has the feel of wood grain, finely ground solid particles, preferably a flour of solid wax particles in the embodiment illustrated, are added to the paint in sufficient quantity to produce a surface finish of preferably between 63 and 125 micro inches when included at 15 grams/liter. In addition, it provides the additional solids content to produce a thickened grain coat.

A wood grain effect application means generally indicated at 9 is provided at one end 10 of the carriage assembly 1 adjacent a front edge 11 of the surface 5 of the object 3.
The wood grain effect application means 9 in the embodiment illustrated comprises a ridged spreader means generally indicated at 12 and means, generally indicated at 13, to control axial, rotational and lateral movement of the ridged spreader means 12. In the embodiment illustrated the ridged spreader means 12 includes a ridged spreader plate 14 attached to a moving ridged plate carrier 15. The means 13 to control axial, rotational and lateral movement of the ridged spreader means 12 in the embodiment illustrated includes a slave cylinder assembly 16 and pseudo random motion generator means generally indicated at 17. The ridged spreader means 12 and means 13 to control axial, rotational and lateral movement of the ridged spreader means 12 are described in greater detail below.

As the freshly painted object 3 is passed under the moving ridged spreader plate 14 preferably at a fixed rate, for example about 80 feet/minute, a wood grain effect may be produced by drawing the moving ridged spreader plate 14 through the freshly applied wet paint (or grain coat) on the object 3, and then drawing the paint into ridges that emulate the grain ridges found in natural wood. The paint ridges settle in the previously applied base coat with a surface finish of preferably 63 to 125 micro inches. The solid particles in the paint cause small pits in the surface finish of the base coat allowing gradual thinning of the grain coat margins. As the paint ridges thin out, the roughened surface produces half tones of color. As the grain coat thins, different pigments in the paint of the base coat and top paint coat layer become more pronounced, thereby achieving a color half tone. With the unusually rough surface finish achieved, and the increased solids content of the paint, pronounced half tones become apparent, and the thickened grain coat produces raised grain ridges which have the feel of natural wood. These factors enhance the believability of the finished product.

These painted finishes can be produced in natural wood colors, and subsequently stained to customer requirement.
The stain may have the same characteristics as the base coat and grain coat paints.

In order to generate a non repeating pattern, a pseudo random movement is applied to the ridged spreader plate 14.
This movement is generated by pseudo random motion generator means 17. In the embodiment illustrated the pseudo random motion generator consists of three hydraulic sine wave generators 18,19,20. Each of the hydraulic sine wave generators 18,19,20 (see Fig 3) have a d.c. motor 21 that rotates an eccentric cam 22. The cam 22 pushes opposing piston rods 23, 24 into their respective hydraulic cylinders 25,26 (shown in Figure 3 in section). This displaces hydraulic fluid to produce hydraulic outputs 27,28 that are sinusoidal in nature. Two outputs 27,28 are provided with each generator unit. These outputs are equal in volume and opposite in amplitude, producing a constant volume system.
One output 27 generates a "push" motion, whilst the other 28 generates a "pull". These two opposing outputs 27,28 are utilized to produce controlled reciprocating motion of the slave cylinder assembly 16 described below.

Motor speed may be controlled by a commercial pulse width modulator 29 with a feedback loop to permit accurate control of motor rpm.

Each of the sine wave generators 18,19,20 is designed to produce a different sinusoidal output. In the present embodiment the different sinusoidal outputs and the resulting wood grain effect are designed using computer simulation. As shown in Figures 5A, 5B and 5C, the simulator reproduces three dissimilar sine waves one to be produced by each of the hydraulic sine wave generators 18,19,20. The simulator summates them in the same manner as the pseudo random movement generator means and translates this summation into a graphic (Figure 5D) depicting the wood grain pattern achieved using the specified control inputs. A
sample of the simulated wood grain is shown in Figure 11.
The control inputs for the simulator, as on the actual machine are sine wave generator cam offset, sine wave generator rpm's, and speed of product throughput.
Simulating the results of different control inputs allows pre-production design of aesthetically pleasing wood grain patterns without wasting paint, material and machine time.
It also enables the remote emulation of different species of tree, (hardwoods, softwoods etc) for customer approval.
As shown in Figure 4 the pseudo random movement generator means 17 is formed by combining the outputs 27,28 of each of the individual sine wave generators 18,19,20. When combined, the outputs of the three hydraulic sine wave generators 18,19,20 can either negate each other, or accumulate into a large wave. The hydraulic outputs from the hydraulic pseudo random movement generator 29,30 vary continuously, producing a pseudo random hydraulic output. This is controlled by varying the frequency of each sine wave generator 18,19,20.
Figures 5A, 5B, 5C show three illustrative sine waves of different frequency (typical of a production requirement) and in Figure 5D the pseudo random effect generated by summing them.

The three "push" outputs 27 of the sine wave generators 18,19,20 are connected to a common output 29. The three "pull" outputs 28 of the sine wave generators 18,19,20 are connected to another common output 30. Each sine wave generator 18,19,20 in the embodiment illustrated runs at a different frequency.

The "push" and "pull" outputs 29,30 remain equal in volume, and opposite in amplitude maintaining the constant volume hydraulic system. The combined outputs 29,30 are fed to the slave cylinder assembly 16 (see Figure 6) to produce a controlled, pseudo random reciprocating motion. This hydraulic output is translated by the hydraulic slave cylinders assembly 16 into rotational movements, axial and vertical, of the ridged plate carrier 15. This carrier 15 is mounted on a mounting assembly, generally indicated at 31, such that it is free to move laterally. Friction between the ridged plate spreader 14 and the object 3 generates the lateral movement at random (uncontrolled) as the object passes by the ridged plate carrier 15.(see Figure 9A and 9B).

Referring to Figures 6,7A,7B,8A,8B, the slave cylinder assembly 16 consists of two opposing slave cylinders 32,33, a shared piston rod 34, a motion takeoff bar 36, two pushrods (for vertical and axial rotation) 37,38, and the ridged plate carrier 15. The equal and opposite "push" and "pull" hydraulic outputs 29,30 from the pseudo random motion generator means are piped into their respective slave cylinders 32,33. The piston rod 34 is displaced by the ebb and flow of hydraulic fluid, producing an oscillating motion. The amplitude and frequency and direction of this motion is thus slaved to the output from the pseudo random motion generator.

A motion takeoff bar 35 is rigidly connected to the centre of the shared piston rod 34. A vertical rotation push rod 37 connects the motion takeoff bar 35 to the ridged plate carrier 15, providing it vertical rotation (see Figure 7A, 7B). Similarly, an axial motion pushrod 38 connects the motion takeoff bar 35 to the ridged plate carrier 15, providing it axial rotation (see Figures 8A, 8B).

As noted above the ridged plate carrier 15 is also free to move laterally. This motion is not controlled directly. It is caused by friction between the ridged plate carrier 15 and the object 3 to which the wood grain effect is applied.
As the ridged plate carrier 15 rotates about its vertical axis, its axle shaft 39 is presented at an angle to the object's 3 travel. This causes the ridged plate carrier 15 to migrate laterally left or right on the mounting assembly 31, depending on the direction of rotation. This action is essentially random in as much as so many factors influence it, it cannot be predicted. This degree of randomness enhances the believability of the finished product.

As noted above in the embodiment illustrated a ridged spreader plate 14 (see Figure 10 is wrapped around the bottom surface 40 of spreader plate carrier 15. When so assembled, and pressed onto the surface 4 of an object 3, it forms a line contact with the object. As the ridged spreader plate 14 is moved, the points of contact vary continuously, spreading the paint into simulated wood grain ridges.

The pattern of ridges 41 shown in Figure 10 are illustrated as semi-circular may be varied. Alternate designs would include, among others, elliptical ridges, diagonal ridges, or irregular patterns. Each design would produce distinct variations to the finished product. In addition, the number of ridges may be decreased to produce open grain designs, or increased to produce tighter grains. The present invention is not restricted to any particular design or pattern of ridges.

Although various preferred embodiments of the present invention have been described herein in detail, it will be appreciated by those skilled in the art, that variations may be made thereto without departing from the spirit of the invention or the scope of the appended claims.

For example the method of summation of three dissimilar sine waves to produce a pseudo random movement may be varied.
With the technology available today, producing this movement by hydraulic means is expedient. The same movement may be produced in the future by a computer driving a linear motor.
The particular method of production of the pseudo random movement is largely unimportant.

In the illustrated embodiment control of the sine wave generators rpm's is being achieved by driving a d.c. motor via a pulse width modulating device with a feedback loop.
Many other controllable motor drives exist that would fulfill this function. The present invention is not dependent on the means of speed control.

The roughened surface finish of the paint coats helps to produce a believable wood grain effect. It is achieved in the embodiment illustrated by the inclusion of solid wax particles. Other additives, either natural (crushed nutshells etc) or synthesized, may produce the same surface finish. The present invention is not dependent on the use of any particular additive to produce the desired surface finish.

The present invention is capable of generating a painted, exterior grade wood grain pattern, on various materials, including plastic products, with the feel and look of natural wood.

Principal advantages of the present invention over known methods of attempting to apply a wood grain effect may include all or some of the listed advantages subject to application:

Over printed non repeating pattern finishes: better surface texture and feel ability to stain finished product ultra violet resistance applicable to odd shapes and sizes rated for exterior use Over Foil non repeating pattern Finishes: better surface texture and feel ability to stain finished product ultra violet resistance improved adhesion rated for exterior use Over polychromatic finish Embossing: applicable to odd shapes and sizes non repeating pattern ability to stain finished product better surface texture and feel believability Over non repeating pattern Melamine: better surface texture and feel ability to stain finished product ultra violet resistance applicable to odd shapes and sizes rated for exterior use It is to be understood by one of ordinary skill in the art that the present discussion is a description of exemplary embodiments only, and is not intended to limit the broader aspects of the present invention.

Claims

1. A simulated wood grain effect applied to an object where the simulated wood grain effect comprises a base coat, said base coat having a paint base selected from the group consisting of waterborne, latex, solvent and oil based paints having a textured surface finish and a top paint layer formed by drawing freshly applied wet paint on the base coat into ridges that emulate the grain ridges found in natural wood.

2. The simulated wood grain effect of claim 1 wherein the textured surface of the base coat is formed by adding finely ground solid particles to the paint base.

3. The simulated wood grain effect of claim 2 wherein the finely ground solid particles are solid wax particles.

4. The simulated wood grain effect of claim 3 wherein the surface finish of the base coat is between 63 to 125 micro inches.

5. The simulated wood grain effect of any one of claims 1 to 4 wherein the top paint layer is a contrasting colour to the base coat.

6. The simulated wood grain effect of any one of claims 1 to 5 wherein the top paint layer is formed using the same type of paint as used to form the base coat.

7. A method of producing a wood grain effect on an object by drawing a moving ridged plate through freshly applied wet paint over a base coat on an object, and then drawing the paint into ridges that emulate the grain ridges found in natural wood.

8. The method of claim 7 wherein the base coat is formed using a paint base selected from the group consisting of waterborne, latex, solvent and oil based paints having finely ground solid particles added to the paint base to give a textured surface finish.

9. The method of claim 8 wherein the solid particles are solid wax particles.

10. The method of claim 7, 8 or 9 wherein the base coat has a surface finish of between 63 to 125 micro inches.

11. The method of any one of claims 7 to 10 wherein movement of the ridged plate is a pseudo random movement axially, vertically and laterally.

12. The method of claim 11 wherein pseudo random movement of the ridged plate is controlled using multiple hydraulic sine wave generators whose combined outputs create a pseudo random hydraulic output.

13. Apparatus to apply a simulated wood grain effect to an object where the simulated wood grain effect emulates the grain ridges found in natural wood, the apparatus comprising a ridged spreader means having a ridged spreader plate attached to a moving ridged plate carrier, means to control axial, rotational and lateral movement of the ridged spreader means.

14. The apparatus of claim 13 where the means to control axial, rotational and lateral movement of the ridged spreader means is a slave cylinder assembly and pseudo random motion generator means.

15. The apparatus according to claim 14 wherein the random motion generator means comprises multiple hydraulic sine wave generators whose combined outputs create a pseudo random hydraulic output.

16. A paint for producing a wood grain effect on an object comprising a paint base selected from the group consisting of waterborne, latex, solvent and oil based paints having finely ground solid particles added to the paint base to give a textured surface finish.

17. A method of simulating the results of producing a wood grain effect on an object by drawing a moving ridged plate through freshly applied wet paint over a base coat on an object, and then drawing the paint into ridges that emulate the grain ridges found in natural wood, said method comprising varying different control inputs pre-production without wasting paint, material and machine time.