This application claims benefit of provisional application 60/943,943,317 filed on 12/6/2007 and provisional application 60/952,431 filed on 27/7/2007, the entire contents of which are incorporated herein by reference.
Background
Residential and commercial building products include interior building products such as drywall, countertops, bathroom fixtures, cabinets, interior doors, floors, wall panels, ceilings, and exterior building products such as decking, wall panels, cladding, fencing, windows, and exterior doors. These products are made from gypsum, vinyl, acrylic, hardboard, toughened glass, annealed glass, resin composites, various laminates, plywood, unsightly carpet tile, fiberglass, ceramics, granite, plastics and plasticized wood composites, and various other materials. It is often desirable to provide such components in a finished style with various graphic designs printed on the material.
Conventional printing techniques such as embossing and ink jet printing are generally aesthetically unappealing. Such as sandblasting and veneering processes have the disadvantage of being costly.
It can be seen that laser engraving the building product will provide an attractive way to decorate the building product. However, commercially manufactured lasers have not been used to decorate building products in a mass production manner at economically attractive speeds. It is believed that at least two factors explain why building products are not mass produced using laser etching. These factors are the relatively low scan speed and the relatively low power capability of commercial laser etching systems.
With respect to scan speed, the laser beam may be driven by a linear motor or lead screw drive on the x-y stage at typical laser scan speeds of typically 0.5 meters to 3.0 meters per second. This method is common in the laser cutting industry using, for example, 1,000-10,000 watt lasers for cutting steel. Such asTrumph、Andthe company of (a) provides such a 1,000-10,000 watt laser system.
The speed of these conventional linear motor driven laser systems is such that etching only one square foot of material will take processing times of several minutes. For example, the leading laser system, Vyteck L-Star, recently advertised, claims it to be the "fastest laser system for the stone, tile, and glass industries in the world". The advertisement also states that "L-Star has a carving speed of up to 150 inches/second or 3.8 meters/second leading the industry".
However, the inventors have realized that the speeds achieved by conventional linear motor systems do not allow for an economical scribing process of building products, since it takes too long to finish the substrate. It is estimated that this linear motor type laser takes several minutes to etch a pattern of graphics per square foot on a building material. For example, at this speed, it is estimated that it will take 6 minutes to etch a complex graphic pattern on a square foot of medium density fiberboard (a common substrate for building materials). Therefore, the unit manufacturing cost would be too high to economically handle such building materials on a large scale. The low speed of such linear motors would not be a practical or economical method of laser forming (laze) graphic patterns in large quantities on wood composite decking, flooring, wood composite products, or any other typical building product substrate. Laser forming complex wood grain patterns on one square foot of engineered or plasticized wood using current laser engraving techniques will take several minutes per square foot. The inventors believe that this is why such building materials cannot be etched by laser in large quantities.
Alternatively, galvanometer-driven mirrors (called galvanometer mirrors for short) may be used to control the movement of the laser beam over the surface of the material. The galvanometer mirror is moved by a control signal and the movement correspondingly causes the output beam of the laser to move along a desired path over the material, thereby enabling the generation of a pattern. The method has wide application in laser engraving of various materials including steel, wood and plastics using 50-250 watt lasers.
Laser systems driven by galvanometer mirrors can be employed on relatively small scales (typically less than 61cm (or two feet) square field sizes) and at low speeds (engraving speeds less than 5 meters per second) using low power (typically between 50-250 watts). These systems typically etch products such as wine glasses, small brass bushings, small wooden sheets, or small granite slabs. Unlike other lasers that use linear motor drives, galvanometer mirror driven systems have laser power that is not sufficient to handle relatively large components. As with lasers driven using linear motors, the operation of galvanometer mirror systems is too slow to economically produce building product parts.
Detailed Description
Reference will now be made in detail to the exemplary embodiments and methods of the present invention as illustrated in the accompanying drawings, wherein like reference numerals refer to the like or corresponding parts throughout the several views. It should be noted, however, that the invention in its broader aspects is not limited to the specific details, representative apparatus and method, and illustrative examples shown and described in the detailed description.
The inventors are unaware of any high speed engraving process that has been suggested prior to the present invention using a high power laser. The inventors have determined that the use of high power (greater than 500 watts) and high speed (greater than 10 m/s) lasers would be a significant improvement over conventional systems and a commercially viable method of laser patterning and patterning of build product substrates and other materials in mass production to achieve low unit cost and thus satisfactory economics.
In certain exemplary embodiments, 2,000 watt or more and even 2,500 watt or more lasers coupled to ultra-high speed scan heads at 30 meters/second or more provide attractive unit manufacturing costs and economies. The inventors have calculated that laser scan speeds of 30-50 meters/second are capable of etching graphic patterns in a time frame of a few seconds per square inch and at a unit cost of a few cents per square foot. Here, "velocity" is the velocity of the laser output (e.g., beam) relative to the surface of the material. Relative velocity is imparted by moving the laser output while holding the material stationary, or by moving the material while holding the laser output stationary, or by moving the laser output and the material simultaneously in different directions and/or at different speeds.
According to an exemplary embodiment, high speed, high power lasers are used to form patterns and designs on building material substrates. The laser, indicated by reference numeral 32 in fig. 1, is a high power laser having an output power greater than 500W, and in certain exemplary embodiments, greater than 1000W (1kW), 2000W (2kW), or even greater than 2500W (2.5 kW). The laser power output referred to herein is continuous, as opposed to when the laser has a temporary surge or when the laser is pulsed. The continuous power can be varied by adjusting the power setting on the laser. The laser frequency is typically in the range of, for example, 10 to 60 kHz. An exemplary commercial laser is 2.5kW CO provided by Rofin-Sinar technologies Inc2Laser, model DC 025.
The output 34 of the laser 32 is coupled to a scanning head 36, which scanning head 36 includes a controllable, movable, relatively lightweight coated mirror that is capable of scanning the laser output at relatively high speeds. In an exemplary embodiment, the speed is greater than 10m per second, or even greater than 30m per second or higher speeds when using higher power lasers. As described herein, scanning speeds of up to 65m per second or even higher may be employed. In addition, the laser output 38 may scan across a workpiece on the work surface 40, as shown in FIG. 1. For example, the output 38 may scan a length of 0.9m (3 feet) or more.
The laser system according to this embodiment uses very high scanning speeds to achieve low unit costs when processing materials, such as structural or decorative building materials. Examples of materials that may be treated using the systems and methods embodied herein include glass (tempered and/or annealed), stone, ceramic, granite, engineered wood, laminates, metal, plastic, gypsum, wallboard, fiberglass reinforced plastic (fiberglass reinforced plastic), wood composite, vinyl, acrylic, hardboard, plywood, unsightly carpet tile, and the like. Lasers according to embodiments of the present invention that scan at such high speeds employ exceptional power to provide high energy density per unit time for satisfactorily etching patterns on building materials and other substrates at industrial production levels. Lasers operating at high scan speeds of 30-50 meters per second at laser powers below 500 watts will not have sufficient power to effectively etch graphic images on building products.
To provide a laser system with 1,000-2,500 watts driven by a galvanometer at high scanning speeds (e.g., in the range of 30-50 meters/second), in an exemplary embodiment of the present invention, a commercially available light weight high technology mirror system with high temperature coatings is used. An exemplary commercially available lightweight high technology mirror system is a ScanLab AG model PowerSCAN33 Be 3-axis galvanometer scanner with a 33mm beryllium mirror. High temperature coatings are believed to be physical vapor deposited alloys. Coating a light-weight beryllium substrate with a material enables the mirror surface to reflect 98% of CO2Laser (wavelength 10.6 microns). The lightweight high-technology mirror system enables a galvanometer (or simply "galvanometer") to move the laser output (e.g., beam) over the substrate surface in a repetitive but efficient manner. The scanning speed of such laser systems is surprisingly an order of magnitude higher than that obtained using linear drives or conventional galvanometer mirrors. Using such a lightweight mirror system, the inventors have achieved laser scanning speeds in excess of 65 meters per second, as compared to the maximum scanning speed of 4-5 meters per second of conventional laser engraving techniques.
The system includes a controller, designated by reference numeral 30 in fig. 1, which is capable of keeping up with the ultra-high scanning speed produced by the light weight mirrors and making the necessary power changes at the specified speed. To produce high resolution patterns, the controller performs these power changes at high speed, for example, every few millimeters of beam scanning. The scanning speed of the laser will determine the amount of power change in the pattern. The type (e.g., complexity and intricacy) and depth of the pattern also affect how it is scribed on the substrate. An exemplary commercially available Controller is an Embedded Laser Process Controller (Embedded Laser Process Controller) supplied by LasX industries, inc. The interdependence between power change, control speed, and laser scan speed is shown in tables II and III below.
Fig. 2 illustrates another embodiment of a system for scoring a material, such as a building material. The system, generally indicated by reference numeral 10, includes a laser 11 for generating a laser beam 12 in the direction of a computer controlled mirror system.
The illustrated mirror system includes an x-axis mirror 13 rotatably mounted on and driven by an x-axis galvanometer 14. The x-axis galvanometer 14 is adapted to rotate and cause the x-axis mirror 13 to rotate. When the laser beam 12 strikes the mirror 13, the rotation of the x-axis mirror 13 causes the laser beam 12 to move along the x-axis. A (digital) control computer 15 controls the output of the power source 16 to control the x-axis galvanometer 14 to rotate the x-axis mirror 13. Laser beam 12 is deflected by x-axis mirror 13 and directed toward y-axis mirror 17 which is rotatably mounted on y-axis galvanometer 18. The y-axis galvanometer 18 is adapted to rotate and cause the y-axis mirror 17 to rotate. The rotation of the y-axis mirror 17 causes the laser beam 12 incident on the mirror 17 to move along the y-axis. The control computer 15 controls the output of the power source 16 delivered to the y-axis current meter 18 to control the rotation of the y-axis current meter 18.
The laser beam 12 is deflected by a y-axis mirror 17 and directed through a focusing lens 19 adapted to focus the laser beam 12. The lens 19 may be a multi-element field-of-plane focusing lens assembly, the lens 19 optically maintaining a focal point in plane as the laser beam 12 moves through the material to scribe a pattern. The lens 19, mirrors 13, 17 and galvanometers 14, 18 may be housed in a galvanometer block (not shown).
The apparatus 10 also includes a work surface 20, which work surface 20 may be a solid substrate such as a table or even a fluidized bed. A material (or workpiece) 21 is placed on the work surface 20. The material 21 includes a work surface 22 to be scribed. The working surface 20 can be adjusted vertically to adjust the distance from the lens 19 to the surface 22 of the material 21. The laser beam 12 is directed by mirrors 13, 17 to a work surface 22 of a material 21. Typically, the laser beam 12 is directed generally perpendicular to the work surface 22, but different patterns can be achieved by adjusting the angle between the laser beam 12 and the work surface 22 between about 45 ° and about 135 °. Relative movement between the laser beam 12 in contact with the working surface 22 of the material causes the pattern 23 to be scribed on the surface 22. The digital control computer 15 controls the movement and timing of the mirrors 13, 17 and the power of the laser beam 12 in order to scribe a particular desired pattern 23. As mentioned herein, relative motion may involve moving the laser beam 12 while the work surface 22 remains stationary (e.g., using a mirror system), moving the work surface 22 while the laser beam 12 remains stationary, or simultaneously moving a combination of the laser beam 12 and the work surface 22 in different directions and/or at different speeds.
A second computer, such as a workstation computer (not shown), may be used in the method to facilitate forming the desired pattern. For example, the graphics may be scanned onto a workstation computer, converted to the appropriate format, and then introduced into the control computer. The digital control computer then controls the galvanometers 14, 18 and mirrors 13, 17 and the power output of the laser beam 12 to form a pattern on the surface of the material 22 at the appropriate power and moving speed for high throughput.
The system 10 may also include a tank 24 to inject a gas, such as an inert gas, into the work zone. The amount of gas may be controlled by a digital control computer or other means.
The term scribe as used herein means contacting a material with a laser beam to form a pattern. During scribing, the laser beam 12 applies power to the substrate to produce a visually perceptible change to the substrate, for example, by removing a coating of the substrate, removing material of the substrate, and the like. The result is a visually perceptible change in the substrate. The term graphic means decorative and artistic designs, non-decorative designs, patterns, graphic images, looks, alphanumeric characters, indicia, other markings, and the like.
Two techniques for scribing patterns on materials include raster and vector techniques. Raster technology may be defined as the drawing of a pattern by the laser scanning back and forth in a continuous fashion in either the horizontal or vertical direction until the pattern is complete. Vector painting may be defined as laser tracing the outline of each individual portion of a graphic until the entire graphic is completed.
The amount of laser power required to provide an acceptable design at high speed will be determined by the nature of the substrate. The laser power may range anywhere above 500 watts and up to, for example, 5,000 watts. For example, the power required to laser process cotton shirts or filaments at high scan speeds may only require 500 watts, whereas laser processing effectively on plasticized wood, engineered wood, or denim at similar scan speeds may require much higher power, e.g., 2,500 watts or more. This concept can also be applied to smaller sized substrates, for example for large scale customization.
According to one embodiment, control information for controlling the laser may be stored in advance in the controller 30. The stored control information may be linked to one or more different graphics, e.g. patterns.
The inventors have obtained a variety of materials and building products, including plasticized wood, vinyl siding, wood composites, drywall, laminate products, hardboard, wood fiber products, tempered glass, annealed glass, drywall, vinyl, ceiling tile, flooring, fiberglass and resin compositions, carpet tiles, and have attempted to achieve fashion designs on these components using high speed (greater than 10 meters per second and preferably 30 meters per second) and high laser power (greater than 500 watts, and in particular embodiments 2,000 watts or more or up to 2,500 watts). The results of the tests are simply surprising, since in each case a laser can be used for about a few seconds to achieve a remarkable and artistic design on these products. Thus, the techniques disclosed in the embodiments provide for the first time an economic breakthrough for laser etching graphical images on building products.
The inventors were surprised to be able to scribe attractive and complex graphic designs and textures on acrylic, vinyl and fiberglass building product parts, plasticized wood and wood composites at high speeds. Various patterns and wood grain patterns are drawn on these building materials in a time frame of a few seconds per square inch. The ordinary "vanilla" decorative product is converted into a decorative part in a few seconds. Oak, walnut, cedar, and mahogany wood grain patterns are laser formed on plasticized wood and wood composites to provide a realistic wood-mimicking decking member. Even fanciful wood grain patterns and graphic patterns, such as leopard wood grain patterns and other flower patterns, are laser formed on plasticized wood and wood composites at high throughput speeds to give attractive new designs. Most importantly, such a design is produced in such a short time frame that the laser etching process is in fact economical for mass production. The laser formed graphics on drywall add a new degree of freedom to the aesthetics of the interior wall design and represent another surprise. Laser forming different textures on flooring products ranging from hard and soft boards to ceramic boards provides a new low cost alternative to adding finishes and designs to floors. Etched patterns and designs can even be laser formed on mirrors to provide a completely new aesthetically pleasing appearance for mass production.
The inventors believe that the laser systems embodied herein can provide for the first time nearly unlimited fashion and design features for building products in an economical production process. The inventors have demonstrated that a 2,500 watt laser driven by galvanometer mirrors is indeed capable of decorating building products in a few seconds and is therefore very economical, if not revolutionary, to cost structure. To further improve economy, products may be laser scribed at high speed (e.g., greater than 10 meters per second) and high power (e.g., greater than 500 watts) while coupled to a simple mobile conveyor system. The laser system may "print-on-the-fly" in a continuous laser scribing process. Furthermore, there are some other ways to improve the economy, such as: multiple lasers may be arranged along the production line to double or triple the production capacity; the scan head may be connected to a linear motor that will laser etch a larger material in regions until the entire block is complete; and the distance of the laser to the working surface can be increased to allow a larger block or blocks to be laser etched at one time.
For example, in a continuous process for mass production, laser etching plasticized wood may involve a 2,500 watt laser directed at a 50.8cm (20 inch) working surface that operates at high speed to match the line speed of the process. But in order to properly laser etch an interior door having dimensions of approximately 3 feet by 8 feet for mass production, it may be more efficient to use multiple lasers or linear motors to cover the entire working surface. Regardless of the arrangement, the inventors have determined that laser powers of 500 watts or more (e.g., 500 watts-2,500 watts) and laser scan speeds of 10 meters per second or more (e.g., 10-50 meters per second) yield satisfactory economics of unit cost of laser forming patterns on building products. By increasing the laser speed from industry standard 3.8 meters per second to, for example, 50 meters per second, the actual unit cost can be reduced from a few dollars per square foot to a few cents per square foot.
The power and speed should be controlled to avoid any undesirable over-treatment results, such as complete carbonization, burn-through, and/or melting of the scribed material.
It should be understood that the methods and systems described herein may be used to score materials other than building materials. Other materials that may be scored according to embodiments described herein include, for example, denim fabric and leather in the clothing industry.
The computer hardware and software for performing embodiments of the invention described herein may be of any type, e.g., general purpose or some specific purpose such as a workstation. The computer can beLevel computer, running WindowsWindowsOrOr may beAnd (4) a computer. The computer may also be a handheld computer, such as a PDA, cell phone or laptop.
The program may be written in C or Java, Brew, or any other programming language. The program may reside on a storage medium, e.g., a magnetic or optical storage medium, e.g., a computer hard drive, a removable disk or medium such as a memory stick or SD medium, or other removable medium. The program may also be run on a network, for example, using a server or other machine to send signals to one or more local machines to cause the local machines to perform the operations described herein.
Examples of the invention
To demonstrate the effect of substrate material and graphic image pattern on laser power and scan speed, the experiments set forth in table I below were performed on various substrates.
TABLE I
| Substrate | Graphic image | Laser power (watt) | Laser scanning speed (m/s) |
| PVC compound | Cedar | 1750 | 10 |
| Polyethylene wood composite | Cedar | 2500 | 10 |
| Polyethylene wood composite | Maple wood | 2000 | 10 |
| Polyethylene wood composite | Leopard vein | 1750 | 10 |
| Hard fiberboard | Walnut wood | 2500 | 15 |
| Lacquer MDF (2 paint layer) | Simple oak | 2500 | 40 |
| Medium Density Fiberboard (MDF) | Rose petal | 2500 | 15 |
| Medium Density Fiberboard (MDF) | Simple walnut | 1500 | 22 |
| Medium Density Fiberboard (MDF) | Oak cross grain | 1500 | 22 |
| Painted hard fiberboard (2 paint layer) | Maple wood | 1375 | 15 |
| Painted hard fiberboard (1 paint layer) | Simple oak | 2500 | 28 |
| Prime coated hard fiberboard | Simple oak | 2500 | 32 |
| PVC | Cedar | 2500 | 10 |
| Reaction injection molding of plastics | Cedar | 2250 | 10 |
Tables II and III below demonstrate the effect of controller speed on the width of laser power variation for two separate graphic images. Table II contains data for 32 laser lines per inch, and Table III contains data for 60 laser lines per inch. For example, at a controller speed of 10,000 pixels per second, a graphic image with 32 lines per inch that requires a change in laser power every 2 pixels can achieve a maximum laser scan speed of 15m/s (see Table II). In order to multiply the laser speed to 30m/s in this example, the controller should have a processing power of 20,000 pixels per second. As the laser line per inch increases (compare tables II and III), the controller speed becomes more important to maintain high laser line speeds.
TABLE II
TABLE III
The foregoing detailed description of certain exemplary embodiments of the invention has been provided for the purpose of illustrating the principles of the invention and its particular application, so as to enable one skilled in the art to understand the invention for various embodiments and with various modifications as are suited to the particular use contemplated. The description is not intended to be exhaustive or to limit the invention to the precise embodiments disclosed. Although only a few embodiments have been disclosed above, other embodiments are possible and the inventors intend these embodiments to be included within the scope of this specification and the appended claims. The specification describes specific examples to achieve a more general purpose that may otherwise be accomplished. Modifications and equivalents will be apparent to those skilled in the art and are intended to be included within the spirit and scope of the appended claims and their appropriate equivalents. This disclosure is intended to be exemplary, and the claims are intended to cover any modifications or alterations as may be contemplated by those skilled in the art. For example, other types and wattages of lasers may be used using this technique than those described above.
Only those claims using the term "means for. Furthermore, unless a limitation from the specification is explicitly included in a claim, such limitation should not be attached to any claim.