Patent Application
20090130328
The present invention is directed to an apparatus and method for curing a coated surface material. The methods are particularly well suited for curing surfaces of vehicles such as automobiles.
A surface coating is generally applied to a damaged portion of a vehicle, to return the surface of the vehicle to its prior undamaged appearance. To repair the damaged portion of a vehicle panel, a combination of mechanical forming putties, fillers, primers, paints and topcoats are typically used. Many of these materials are dissolved in solvent based carriers and require significant amounts of time for solvent evaporation and resin curing. Attempts have been made to accelerate this process using heat or infrared irradiating devices in baking tunnels or chambers.
Heat-based curing methods have disadvantages in that they require time before an appropriate curing temperature is reached and once that temperature is reached, the heat or infrared energy is not localized to the region where curing takes place. This leads to heating of areas surrounding the intended curing region. Once curing is completed, both the surface coating and surrounding area must be cooled before the repair can be continued. Both the heating and cooling processes extend the amount of time required to complete a given repair.
New compositions and methods for curing surface coatings are needed that are faster and easier to employ. Such methods can be used to improve the efficiency and speed with which a repair operation can be completed.
The present invention is directed to compositions and methods for curing a surface that is coated with a curable resin. In one embodiment, the apparatus includes an electromagnetic radiation source adapted to cure a curable resin, a cooling system that maintains an optimum temperature that optimizes energy output of the radiation source and vents exhaust air away from the target surface, a positioning panel that holds the electromagnetic radiation source and cooling system and allows the electromagnetic radiation source to be rotated both in the horizontal and vertical directions such that the apparatus can be accurately directed towards the target surface. The invention can include a ballast that provides proper starting and operating electrical conditions for powering the electromagnetic radiation source.
In an embodiment, the invention includes an ultraviolet radiation source. The ultraviolet radiation source can include at least one fluorescent bulb.
In an embodiment, the invention includes a ballast. The power of the ballast can be greater than or equal to the power required to drive the radiation source. In more preferred embodiments, the power of the ballast is greater than the power required to drive the radiation source.
In an embodiment, the invention includes an infrared radiation source. Certain embodiments can also include an ultraviolet radiation source and an infrared light source.
In an embodiment, the invention includes a cooling system. The cooling system can include a variable speed fan. The fan can be controlled such that its speed depends, in part, on the relative proportion of ultraviolet light and infrared light emitted by the apparatus alternatively the fan can be controlled by the temperature inside the positioning panel. The cooling system can be configured to vent exhaust air away from the target work surface to assist in maintaining a clean surface. In alternate embodiments, pressurized or compressed air can be used to cool the radiation source.
In an embodiment, the invention can include a heat sensor. The heat sensor can be configured to shut off the light source when the heat passes a predetermined threshold temperature. The heat sensor can be configured to measure the temperature of the radiation source, the internal confines of the panel, the curing surface or other area in the vicinity of the positioning panel, as desired.
In an embodiment, the invention includes a positioning panel. The positioning panel can hold a radiation source and a cooling system. The positioning panel provides for rotation of the radiation source in both the horizontal and vertical direction such that radiation can be accurately directed towards the target work surface.
In an embodiment, the ultraviolet radiation source comprises a fluorescent light or a plurality of fluorescent lights which can be arranged in the positioning panel. The ultraviolet radiation source can also be a light emitting diode or at least one laser.
In an embodiment, the invention can include a positioning panel having a reflector. The reflector can be positioned such that radiation can be reflected in the direction of the target work surface.
In an embodiment, the invention can include a timer for timing a curing treatment.
In an embodiment, the invention can include a visual reference aid for visually assisting in the positioning of the positioning panel.
In an embodiment, the invention can include a counter for measuring the operational life of the ultraviolet light source.
In an embodiment, the invention can include a radiometer for measuring the amount of ultraviolet light transmitted to a work surface.
In an embodiment, the invention includes a distance sensing device for measuring the distance of a positioning panel from a work surface. The apparatus can also include an alarm to alert an operator that the positioning panel is positioned at an inappropriate distance from a work surface.
The invention is also directed to methods for curing a surface that is coated with an ultraviolet light-curable surface coating. To this end, the surface coating material can contain a polymeric resin containing an ultraviolet reactive photo-initiator compounds that are suitable for initiating curing or crosslinking of the resin polymer molecules. The method involves obtaining a radiation source suitable for curing and directing radiation from the source onto the surface coating using a curing apparatus of the invention to form the cured surface. It is desirable that the temperature of the curing surface remain substantially near ambient temperatures. Thus, temperature increases of about 20° C. or less are preferred, more preferably temperature increases of about 10° C. or less are preferred, more preferably temperature increases will be about 5° C. or less, still more preferably the temperature increases are less than about 3° C.
In a method, the invention is also directed to repairing a surface wherein a surface coating material containing an ultraviolet reactive photo-initiator compound is obtained. The material is applied to a surface in need of repair. An ultraviolet radiation source is obtained and ultraviolet radiation is directed onto the surface coating material to form a cured surface coating while maintaining the temperature of the surface at substantially ambient temperature.
Additional features and advantages of the invention are described in, and will be apparent from, the following Detailed Description of the Invention and the Figures.
The present invention provides an apparatus for use in curing surfaces coated with curable resins. The apparatus emits radiation that assists in the curing process. Depending upon the wavelength of radiation emitted by the apparatus, curing can occur with minimal heating of the curing surface. This can improve the speed of repair procedures which do not require the repair technician to wait for the surface to cool down after curing. The apparatus can be used with ultraviolet curing resins that have exceptionally quick curing properties and that contain low quantities of volatile organic compounds (VOCs). Because they have low quantities of volatile organic compounds, such materials require minimal drying/evaporation time. Alternatively, the apparatus can also be used with traditional curing resins, which can be cured by either ultraviolet or infrared radiation.
In an embodiment, the apparatus can include a radiation source suitable for curing a curable resin, a cooling system that can maintain an optimum temperature for maximizing the energy output and venting exhaust air away from the target surface, a positioning panel for holding the radiation source and cooling system. The positioning panel can be rotated both in the horizontal and vertical directions such that the radiation can be accurately and uniformly directed towards the target surface. The apparatus can include a ballast that provides proper starting and operating electrical conditions for the radiation source.
The radiation source can be a fluorescent light or a plurality of fluorescent lights which can be arranged in the positioning panel. Such a source can be used to emit a broad wavelength range of light, including ultraviolet light. The ultraviolet radiation source can also be at least one light emitting diode or at least one laser. In addition to fluorescent lamps, suitable ultraviolet emission sources include LEDs, electron beams, lasers, and the like so long as radiation of a suitable wavelength and intensity for curing the resin is emitted. The curing apparatus of the present method can employ a plurality of fluorescent tubes mounted to a positioning panel that can be directed towards the targeted work surface. By providing a plurality of radiation sources, a greater area of repair can be achieved in a single curing operation. The positioning panel can have an area greater than one square foot, more preferably the positioning panel has an area greater than two square feet, still more preferably the positioning panel has an area greater than three square feet. The upper size limit for the positioning panel is only limited by the capacity of the stand used to support it.
In an embodiment, the radiation source is an ultraviolet radiation source. When the apparatus emits ultraviolet radiation, UVA radiation is preferred. Such radiation will typically have a wavelength ranging from about 315 nanometers to about 400 nanometers. The use of UVA radiation is preferred because it is safer for the operator and other bystanders within the operating field than UVB and UVC emitting devices.
In embodiments that utilize tube lights, the tubes can be of any suitable length which includes any lengths that can be conveniently fit into a positioning panel. For example, lengths for positioning panel bulbs can be industry standard lengths, including about 21, 32, 36, 46, 48, 58, 72, 84, or 96 inches but other lengths such as about 19, 30, 34, 44, 46, 56, 70, 82, or 94 inches can be used. As can be appreciated, the invention allows for the use of any bulb length. In addition, the radiation source can be a laser, LED, halogen lamp, or other light source.
In an embodiment, fluorescent lamps of the apparatus can have an optimum temperature at which ultraviolet energy output is maximal. To maintain this temperature, air can be drawn over the surfaces of the lamp to provide cooling. In an embodiment, cooling air can be drawn up from the work surface into the positioning panel where it contacts a lamp. A blower, fan or pressurized air can be used for this purpose. Preferably, the air is exhausted away from the work surface, for example out the back of the positioning panel. Particles or dust in the surrounding air, can also be drawn into the apparatus by means of this airflow and away from the targeted work surface. This keeps dust or deposits from contacting the work surface and the surface coating material before and during the curing process. Such dust can lead to inferior quality work or can require the work to be repeated. The airflow through the apparatus ensures that the apparatus can be positioned close to the work surface without disturbing or depositing dust or particles on the surface under repair and helps to ensure that the apparatus and bulbs will not overheat.
In an embodiment, the power of the ballast can be greater than or equal to the power of the bulb it powers. For example, a 90 Watt fluorescent bulb could be used with a 100 Watt ballast. The invention is not limited to any particular difference between bulb and ballast power. The difference between bulb and ballast power could be about 10, 20, 30, or 40 percent or more, for example.
The invention also covers the use of the curing apparatus with an infrared light source. One of skill can appreciate that infrared radiation will typically have wavelength maxima ranging from about 700 nm to about 1 mm. Infrared radiation produces more heat than ultraviolet radiation, making it preferred for certain resins that can not include ultraviolet photo-initiators. Certain embodiments of the invention can include a ultraviolet radiation source and an infrared light source. When ultraviolet radiation sources and infrared radiation sources are both found in the positioning panel, they can be configured such that they are evenly distributed over the target work site and not concentrated disproportionate to the other in a particular area.
In an embodiment, the cooling system can include a variable speed fan, which can have an optimum speed. The fan speed can be made to depend upon the relative proportion of ultraviolet light or infrared light emitted by the apparatus, and the temperature resulting from such radiation. The speed of the fan can be adjusted to maintain the temperature in or near the positioning panel in a desired range.
The invention can include a heat or temperature sensor adapted to shut off the light source when the temperature passes a predetermined threshold value. The heat sensor can also be used to regulate the fan speed such that the fan speed can be increased if the lamps are too hot or decreased if the lamps are too cold.
The curing apparatus can include a positioning panel which can be connected to a mobile support stand for ease of adjustment by the operator. The positioning panel holds a radiation source and a cooling system. The positioning panel can be adapted to allow the radiation source to be rotated both in the horizontal and vertical directions such that the emitted radiation can be accurately directed towards the target work surface with the result that the time required for curing can be minimized.
The positioning panel allows ultraviolet radiation devices of the invention to be accurately directed towards the work surface to maximize the exposure of the repair surface to the radiation. The positioning mechanisms of the apparatus allow the positioning panel to be lifted or rotated both in the horizontal and vertical directions, as needed. The support arm is connected to a mobile support stand, for ease of adjustment by the operator. This provides for accurately locating the ultraviolet device so that the duration required for curing can be minimized.
In an embodiment, the positioning panel can include a reflector for directing radiation toward the work surface. The reflector can be incorporated into the light bulbs or can be included as a component of the positioning panel.
The positioning panel can include a fan for cooling the ultraviolet radiation source. In certain of these embodiments the fan circulates air from the front of the positioning panel facing the work surface to the back of the positioning panel away from the work surface. Alternatively, the cooling source can be provided by heat exchanging devices, by compressed gases, liquids or other methods.
To operate the apparatus, a timer mechanism can be activated and the time required for curing the particular surface coating material set. The location and distance of the positioning panel from the curing material can also be set. Then upon completion of curing, the timer deactivates the radiation source and the operator can continue with repair of the surface.
Because ultraviolet radiation is difficult to detect or is invisible to the human eye, in certain embodiments, a visual reference can be used to aid in properly positioning the positioning panel with respect to the targeted work surface. Any suitable visual reference can be used, for example visible electron beams or lights. In such a configuration, the device can project a visible reference onto the targeted work surface indicating the perimeter of the radiation upon the work surface. Using this system an operator can more accurately and efficiently position the positioning panel and ensure the targeted work area is contained within the radiation field of apparatus.
The apparatus can have a measurement device, such as a mechanical or electronic counter, that keeps track of the duration that the light source has operated. Over the life span of the radiation source, the power output can slowly deteriorate. A timer can be used to record this usage and let the operator know when the radiation source should be replaced.
The apparatus can also be equipped with a sensor, such as a radiometer, that measures the quantity of radiation transmitted to the work surface and adjusts the amount of curing by decreasing or increasing the length of the operating cycle to ensure sufficient but not excessive curing of the coating material. Such a sensor can be used to maintain the quantity radiation transmitted to the work surface to predetermined amounts.
The apparatus can be equipped with a distance-sensing device that can wam the operator that the radiation source and positioning panel are located improperly. A visual and/or audible indicator can be used to wam the operator that the apparatus is located at an inadequate distance for curing and that the operator should reposition the device. This can help to avoid insufficient curing and avoids the need for supplementary curing processes.
The invention also covers methods for repairing or modifying a surface. To this end a surface coating material whose curing can be assisted by the application of radiation, can be applied to a surface, such as a targeted vehicle or vehicle panel. For ultraviolet curable resins, the coating can contain ultraviolet sensitive photo-initiators such that when exposed to sufficient amounts of ultraviolet radiation, a chemical reaction occurs that causes the polymers to crosslink and form a solid three-dimensional network. The result is a durable surface coating that is cured or polymerized.
The method involves obtaining a suitable radiation source and directing the radiation from the source onto the surface coating and curing the coating to form a hard surface. This is most conveniently accomplished using the curing apparatus of the invention. Preferably, surface temperatures remain at a temperature that is substantially at ambient temperature. For example, temperature increases of about 20° C. or less are preferred, more preferably increases of about 10° C. or less are preferred, still more preferably an increase of about 5° C. or less, still more preferably the temperature increases will be about 3° C. or less.
The apparatus of the present invention can be better understood by referring to
Referring to
Positioning panel body 2 of
Radiation source 3, can be a plurality of fluorescent tubes 3A producing an instantaneous ultraviolet lighting type having a spectral range comparable to that of UVA radiation, from about 315 nm to about 400 nm. The spectral peak of the ultraviolet radiation can be varied as necessary depending upon the surface coating material to be cured and its ultraviolet reactive photo-initiator. For example, radiation source 3 can use tubes 3A that can produce infrared radiation.
Radiation source tubes 3A can be arranged parallel to each other in a plane that is offset from the positioning panel body 2. Preferably, the tubes are spaced at equal distances to provide an equal distribution of projected radiation. Radiation source 3A can be connected to positioning panel body 2 by lamp-retaining sockets. For each fluorescent tube there can be a lamp-retaining socket at each end of the tube, providing the electrical connection to the bulb. In addition to the lamp-retaining sockets, positioning panels can include a tube spring clip 7 for supporting the tube. The number, type and arrangement of the radiation device's components can be varied as desired or needed to suit particular curing application.
As further illustrated in
Ultraviolet transmissible barrier 8B can be a high ultraviolet transmittance transparent plastic sheet. Alternatively, the ultraviolet transmissible barrier could be a wire mesh or glass.
Barrier 8B can be adapted to permit any type of radiation, such as infrared energy, to pass from the lamp 3 to the targeted work surface.
A plurality of blowers 5 can be provided on the inner surface of the support box 4A to supply an airflow through positioning panel 1. Air can enter the positioning 1 through air holes 8C in the cage frame 8A. In this case the air flows over the lamp 3 and provides a cooling effect. Air, can then be drawn into the support box 4 through air holes 2B located in the positioning panel body 2. It can be discharged by the blowers 5 venting away from the lamp 3 through the back of the support box 4 and positioning panel body 2. As a result, cool air can be drawn in and therefore does not disturb or deposit dust or particles on the work surface. The number, size and arrangement of both air holes 2A and 8C and blowers 5 can be varied as desired to suit the cooling requirements.
In certain embodiments support frame 9 can be comprised of a structural base 10 containing two longitudinal members 11 joined by a transverse member 12. The transverse member is located between two longitudinal members 10 arranged in the form of the letter “H.” Two longitudinal members 10 are provided with a plurality of casters 13 situated at various positions along the underside of the longitudinal members, allowing the support frame to be easily maneuvered.
Support base 9 includes a vertical support 14 extending from structural base 10 located in the middle of transverse member 12.
Positioning panel 1 can be coupled, by an adjustable arm assembly 15, to vertical support 14. Vertical support 14 can be used to position the positioning panel 1 in a suitable position for curing the targeted work surface. The adjustable arm assembly 15 extends between vertical support 14 and arm support bracket 17 and contains pivotal linkage connections at each end. The adjustable arm assembly 15 can have two parallel, equal length members 16 and the arm support bracket 17 creating a linkage that allows the positioning panel 1 to be infinitely positioned between a minimum and maximum vertical range. A pitman arm 18 can be attached to arm support bracket 17 creating a pivot rotation linkage, providing a means for angular positioning of positioning panel 1 relative to both the vertical axis and horizontal axis. A yoke 19 completes the linkage from pitman arm 18 to lamp head 1. Yoke 19 provides a method for rotation of positioning panel 1 with respect to the horizontal plane.
The efficiency made available by the present invention as described above for curing curable surface coating materials, provides an effective apparatus aiding in automobile panel repair.
This example demonstrates the operation of an apparatus of the present invention in curing a coating on a work surface using ultraviolet radiation and examines the distance dependence of curing and temperature measurements.
Employing the curing apparatus set forth in
Upon measurement of the ambient temperature of each sample plate the following tests and 3 trial runs for each test was performed:
The testing shows that the temperature increase during the curing process is minimal in each case. This allows for repairs to continue immediately after curing, eliminating the need for a cooling cycle as require with other devices.
The test results from each of the three tests are shown below in Table 1.
Please recognize that various changes and modifications to the presently preferred embodiments described herein will be apparent to those skilled in the art. Such changes and modifications can be made without departing from the spirit and scope of the present invention and without diminishing its intended advantages. It is therefore intended that such changes and modifications be covered by the appended claims.
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/CA2005/001670 | 11/1/2005 | WO | 00 | 11/21/2008 |
| Number | Date | Country | |
|---|---|---|---|
| 60624241 | Nov 2004 | US |
