Patent Application
20090307934
1. Field of the Invention
The present invention relates to snow plows and more particularly to snow plow blades treated with a durable, non-stick composition and a method for treating snow plow blades with such a coating.
To move and remove snow and other road debris, a snow plow must be designed to withstand vibration, debris and heavy snow impact, exposure to salt and UV radiation and other rugged environmental conditions over its operating lifetime. Snow plow vehicles depend on the particular plowing application, and can include medium or light duty trucks, a skid or front-end loaders or commercial/government vehicles. A snow plow blade is mounted to the front of the plowing vehicle and has a generally curvilinear shape, to roll the snow upwardly from the bottom and then move it transversely across the face of the blade.
Snow plow blades come in may different types and sizes, depending on the particular plowing application. Snow plow designs can include straight blade, which are single blade designs, or articulated or V-plow blade designs, where the snow plow includes a center plow portion and a snow plow blade or wing extending from each, opposite side of the center portion. In addition, snow plows can also include straight blade and/or articulated blade designs with end extensions, front wearstrips, rear scrapers or top deflectors.
In its simplest form, a snow plow blade includes a support frame, having a substantially arcuate or curved overall cross-section, and a skin or moldboard, also having an arcuate cross-section. The rear side of the snow plow blade is hitched or otherwise attached to the plowing vehicle. The moldboard is secured to the front of the frame and includes a front surface that directly contacts and moves the snow during operation of the snow plow. A wearstrip can also be secured to the front side of the frame near the bottom edge of the moldboard.
In many applications, snow plow moldboards are constructed of steel, aluminum or another lightweight metal, alloy or composite material capable of withstanding the wear conditions usually encountered when plowing. It is intended that during operation of the snow plow, snow is thrown and/or rolled forward across the front face of the snow plow blade and away from the road, and the snow plow vehicle. However, ice and snow can build-up and stick to the moldboard of the snow plow blade, preventing the blade from moving the maximum amount of snow possible, lowering the efficiency of the snow plow.
In addition, when the blade hits an object in the road, a curb or a heavy pile of snow, the front face of the moldboard receives the majority of force of the impact. As such, the moldboard is subject to denting, cracking and failure over time, requiring replacement thereof.
Over the years, there have been several attempts to improve the efficiency and plowing capacity of snow plows while also maximizing the strength and durability of the snow plow blade. For example, one approach is to modify the radius of curvature or surface texture of the moldboard and frame to improve snow deflection. Another approach includes add-on components, such as snow deflectors or wipers to the snow plow to improve efficiency.
Another approach can include lowering the coefficient of friction on the face of the moldboard to minimize ice and wet snow build-up. For example, wax or silicone coatings have been used by snow plow operators to reduce friction on the surface of the moldboard. However, these coatings require substantial cleaning of the snow plow blade and preparation of the snow plow blade surface, such as mechanically roughening up, sanding or priming the surface of the blade, in order for the coating to adhere to the blade. In addition, these coatings simply cover the surface of the moldboard and therefore easily chip and peel off the blade when the blade is struck by rocks, stones and other debris from the roadway, which impact the moldboard under significant forces. Moreover, these coatings may temporarily improve snow rolling characteristics of the moldboard, but they do not add strength or abrasion resistance to the moldboard.
The disadvantages and limitations of the background art discussed above are overcome by the forming an impact resistant snow plow blade having a low coefficient of friction plowing surface, and a snow plow blade formed by said method is provided.
A typical snow plow blade comprises a support frame and a substantially arcuate moldboard or snow plow skin secured to the front of the frame. In some snow plow designs, the snow plow blade also includes a wearstrip secured to the front of the support frame near the bottom of the moldboard, and a rear scraper secured to the rear of the support frame. Depending on the type of plowing application, a snow plow blade, and the corresponding frame and moldboard, can be formed in a variety of lengths and heights. It will be appreciated that the present invention is applicable to all plowing applications, including plow blades formed for light duty or medium trucks, commercial vehicles, and/or small skid loaders.
A typical moldboard has a curved or arcuate shape to enhance the snow rolling characteristics thereof. According to the teachings of the present invention, the moldboard is preferably constructed of a metal material, such as steel. The material of construction can include cold rolled steel, stainless steel, carbon steel or another steel composite or alloy material. Further, other lightweight metals, alloys or composite materials can be used, such as those including aluminum or tungsten. It will be appreciated that the methods of the present invention can be used with moldboards constructed of thermoplastic material, such as polycarbonate, if desired.
In a first step, a snow plow blade, including a support frame and a moldboard is provided in the desired shape and size, and preferably with the desired apertures and/or fittings so that the moldboard and/or wearstrip can be secured to the frame. In certain preferred applications of the present invention, the moldboard is welded to the fame members, for added strength and durably of the snow plow blade. As described above, preferably, the moldboard is constructed of a metal material.
Next, the moldboard, and the frame if provided together, are prepared for painting. In particular, the moldboard and frame surfaces can be cleaned with alcohol, solvent or surfactant to remove any oil, grease, dust and/or dirt present on each of the surfaces. In some instances, and depending on the type of paint selected, the moldboard and frame surfaces can also be grinded or sanded to mechanically dull or rough up the metal surfaces and to remove any rust. Other steps that may be taken to prepare the moldboard and frame surfaces for painting can include applying one or more primers, UW treating or chemically treating the surfaces of the moldboard. It is appreciated that the metal moldboard is preferably prepared for painting in accordance with recommendations by the paint manufacturer.
The frame and moldboard are then painted with a paint including a polyurethane resin as at least one of its binding components. The polyurethane resin is formed, as known in the art, by reaction of an active hydrogen containing compound, such as a polyol, with a diisocyanate or polymeric isocyanate component, in the presence of a catalyst, wherein a sufficient amount of crosslinking occurs between isocyanate groups (—NCO) and the polyol's hydroxyl end-groups (—OH). In polyurethane based paint systems, the resulting polyurethane polymer component is dispersed in an aqueous solution or other solvent of the paint system. When the paint dries or is otherwise cured, a thin film or layer of paint, is present on the surfaces of the moldboard. Consistent with the broader aspects of the present invention, the paint applied to the moldboard surfaces need not be completely dry or cured prior to the coating step.
In a treating or coating step, the plowing surfaces of the moldboard contacted with a 100% solids elastomeric polyurethane system. The support frame plowing surfaces can also be coated with the 100% solids elastomeric polyurethane system, if desired. The rigidity of the layer of polyurethane material coated on to the surfaces of the moldboard and frame depend on the degree of crosslinking of system, and can be a matter of design choice and end-use application. The 100% solids polyurethane system utilized in the present invention is substantially solventless, fast curing, pigment compatible, abrasion and impact resistant, and corrosion and UW resistant.
The 100% solids polyurethane coating system is applied directly to the painted moldboard and frame surfaces. Importantly, the surfaces of the moldboard that are contacted with the 100% solids polyurethane coating require no surface preparation or treatment prior to application. In particular, the methods of the present invention do not require priming, sanding, chemically treating or otherwise pre-treating or preparing the application surfaces of the moldboard and frame. As such, the method of the present invention saves time and expense while also providing the friction-reduced, impact resistant moldboard of the present invention. The methods of the present invention also reduces operator exposure to unnecessary procedures, such as priming, and hazardous chemical materials.
The polyurethane protective coating is cured to form a substantially smooth or level surface having a lower co-efficient of friction than both the bare metal surfaces of the moldboard and frame and the painted surfaces of the moldboard and frame. Without limitation to any particular theory or mode of operation, the 100% solids polyurethane coating material is chemically bonded to at least one functional group or component present in the previously applied paint layer. As such, the excellent adhesion of the 100% solids polyurethane material to the painted surfaces of the moldboard and frame is due, at least in part, chemical or molecular interaction between 100% solids system and the layer of paint. After the polyurethane protective coating is cured, the snow plow blade is ready for use. If the moldboard is provided separately from the frame, the moldboard is installed on the snow plow blade frame after curing, as is known in the art.
It will be appreciated that because the 100% solids polyurethane material is not simply applied over the treated surfaces of the moldboard and frame, but is instead chemically bonded thereto, the protective layer formed by the 100% solids polyurethane material does not easily chip or break away from the moldboard under the heavy stress and impact conditions frequently encountered during a snow plowing season. The resulting snow plow blade is thus provided with a layer of durable protective material that also improves the plowing efficiency of the snow plow blade by lowering the coefficient of friction of the plowing surfaces thereof.
The coated snow plow blade of the present invention is of a construction which is both durable and long lasting, and which will require little or no maintenance to be provided by the user throughout its operating lifetime. The snow plow blade of the present invention is also of inexpensive construction to enhance its market appeal and to thereby afford it the broadest possible market. Finally, all of the aforesaid advantages and objectives are achieved without incurring any substantial relative disadvantage.
These and other advantages of the present invention are best understood with reference to the drawings, in which:
A coated snow plow blade 32 and method of forming such a coated snow plow blade 32, in accordance with the teachings of the present invention, is illustrated in
As illustrated in
The frame 40 comprises a top member 44, a bottom member 46 and vertical side members, indicated generally at 48 and 50, connecting the top and bottom members 44 and 46. The frame 40 can further include a plurality of support ribs 52, support plates 54 and cross members 56 positioned between the vertical side members 48 and 50 to reinforce the frame 40. Other optional elements such as brackets for mounting support shoes to the frame 40 and/or brackets 60 for attaching the snow plow blade 32 to a hitch or vehicle mounting mechanism (not shown in the Figures) can also be included on the rear side 36 of the plow blade 32.
Turning now to
Preferably, the moldboard 42 is constructed of a steel material. The steel material can include cold rolled steel, stainless steel, carbon steel or another steel composite or alloy material, as known to those skilled in the art. Further, other lightweight metal, alloy or composite materials can be used, such as those including aluminum or tungsten. It will be appreciated that the methods of the present invention can be used with moldboards constructed of thermoplastic material, such as polycarbonate, if desired.
As best illustrated in
In certain preferred embodiments of the present invention, the paint is a polyurethane based paint, including the desired pigment color, and additives such as UW or corrosion resistors, if desired. The polyurethane paint can be one or two-part, and includes but is not limited to, acrylic-polyurethane, polyester-polyurethane and other polyurethane blend paints, as are well known to those skilled in the art. The moldboard 42 can be brushed, rolled, sprayed or dip coated with the layer of paint 80. In certain other embodiments of the present invention powdered or particulated polyurethane paint coating can be applied and cured to the surfaces of the moldboard 42.
As will be appreciated, the preferred paint utilized in the present invention includes a polyurethane resin as at least one of its binding components. The polyurethane component is formed, as known in the art, by reaction of an active hydrogen containing compound, such as a polyol, with a diisocyanate or polymeric isocyanate component, in the presence of a catalyst, wherein a sufficient amount of crosslinking occurs between isocyanate groups (—NCO) and the polyol's hydroxyl end-groups (—OH). In polyurethane based paint systems, the resulting polyurethane polymer component is dispersed in an aqueous solution or other solvent of the paint system. When the paint dries or is otherwise cured, a thin film or layer of paint, is present on the application surfaces of the moldboard 42.
Consistent with the broader aspects of the present invention, other types of paints, or paints including a polyurethane component in addition to another binder, can be use to cover the metal moldboard 42. Such paints can include, but are not limited to, those containing alkyd, acrylic, epoxy, silicone, polyester and/or vinyl components.
Depending on the type of paint selected, each of the front face 64, rear face 66, side edges 68 and 70, and top and bottom edges 72 and 74 of the moldboard 42 and frame surfaces can be cleaned and prepared in a step 202, prior to painting. The moldboard and frame surfaces are then prepared according to the paint manufacturer's specifications to ensure proper paint adhesion thereto. In particular, if a polyurethane based paint is selected, the moldboard and frame surfaces can be cleaned with alcohol, solvent or surfactant to remove any oil, grease, dust and/or dirt present on each of the surfaces.
In other instances, and depending on the type of paint selected, the front face 64, rear face 66, side edges 68 and 70, and top and bottom edges 72 and 74 of the moldboard and frame surfaces can be grinded or sanded to mechanically dull the surfaces and remove any rust. Other steps that may be taken to prepare the moldboard surfaces for painting can include applying a primer, or chemically treating the surfaces prior to application of the paint layer 80 to the moldboard 42.
In a treating or coating step 206, the plowing surfaces, such as the front face 64 of the moldboard 42, and front surfaces of the support frame 40 are contacted with a polyurethane coating material 86, as illustrated in
According to the teachings of the present invention, the polyurethane coating material 86 is preferably a substantially 100% solids elastomeric polyurethane system. Most preferably, the polyurethane coating material is a 100% solids aromatic polyurethane system; however, a 100% solids aliphatic polyurethane system or a combination thereof can also be used. The rigidity of the layer of polyurethane material 86 depends on the degree of crosslinking of system, and can be a matter of design choice and end-use application. The 100% solids polyurethane system utilized in the present invention is substantially solventless, fast curing, pigment compatible, abrasion and impact resistant, and corrosion and UW resistant.
It will be appreciated that the 100% solids polyurethane system is also formed, generally, through reaction of an active hydrogen containing compound, such as a polyol, with a diisocyanate or polymeric isocyanate component. Preferably, the 100% solids polyurethane system is a two component system prepared shortly before application to the moldboard 42.
During the coating step 208, the polyurethane coating material 86 is applied directly to the plowing surfaces of the moldboard and frame, absent/without further treatment or modification of the desired application surfaces. More specifically, priming, sanding, UW, plasma and/or chemically treating or other mechanical or chemical surface preparation of the moldboard 42 and/or any other snow plow blade component desired, is not required or advantageous in the methods of the present invention. The paint layer 80 present on the desired application surfaces of the moldboard 42 are contacted or treated with the 100% solids polyurethane system.
In a curing step 208, the polyurethane coating material 86 is cured on to the front face 64 of the moldboard and desired surfaces of the support frame 40 to form a substantially smooth outermost surface thereon. The layer of 100% solids polyurethane material 86 on the front face 64 of the moldboard and frame application surfaces has a lower co-efficient of friction than the painted layer 80 or the bare metal moldboard 42 or frame 40 surfaces. The polyurethane coating layer 86 is preferably sprayed on to the front face 64, however, the polyurethane coating layer 86 can be brushed, rolled or applied in any manner known to those skilled in the art.
Without regard to any particular theory or mode of operation, substantial preparation of the application surface of the moldboard 42 and frame 40 is not required because the 100% solids polyurethane coating chemically interacts, forming at least one of a covalent, ionic and hydrogen bond, with at least one of the functional components of the paint layer 80 on the front face 64 of the moldboard 42 and frame 40. The 100% solids polyurethane coating layer 86 does not merely reside or stick to the outer surface of the polyurethane-based paint layer 80. Rather, the 100% solids polyurethane coating material chemically interacts with and is molecularly bonded to previously applied paint layer 80 at least at the interface thereof.
More specifically, and without limitation to any particular theory, during the curing step 208, the 100% solids polyurethane system components, including reactive isocyanate groups (—NCO) and reactive hydroxyl end-groups (—OH), may activate at least a portion of the functional components of the underlying polyurethane-based paint layer 80. As such, the activated functional components provide additional reaction sites for formation and adhesion of the polyurethane polymer. In addition, hydrogen bonding can occur between the functional groups of the paint 80 and the N—H and carbonyl groups of the polyurethane linkages. As such, the excellent adhesion of the 100% solids polyurethane material to the painted surfaces of the moldboard and frame is due, at least in part, to a chemical bond between 100% solids system and the layer 80 of paint.
The resulting 100% solids polyurethane coating layer 86 is not subject to peeling, bubbling, chipping or cracking away from the painted moldboard surface, as it is chemically bonded to the layer 80 of paint. The 100% solids polyurethane coating layer 86 therefore provides a durable and impact resistant moldboard, having a lower coefficient of friction than an uncoated moldboard and frame, therefore improving not only the strength of the snow plow blade, but also the snow rolling and plowing efficiency of the snow plow blade.
Importantly, and consistent with the broader aspects of the present invention, the 100% solids polyurethane coating layer 86 can be used to repair a damaged or chipped snow plow blade. In particular, the method of the invention can be used to fix a moldboard of a snow plow blade that includes cracks, chips or other damage to the surface or surfaces thereof. In such a case, the 100% solids polyurethane coating layer 86 is applied directly over the cracked or damaged surface without any required surface preparation, as described above.
Although the foregoing description of the snow plow blade and methods of the present invention have been shown and described with reference to particular embodiments and applications thereof, it has been presented for purposes of illustration and description and is not intended to be exhaustive or to limit the invention to the particular embodiments and applications disclosed. It will be apparent to those having ordinary skill in the art that a number of changes, modifications, variations, or alterations to the invention as described herein may be made, none of which depart from the spirit or scope of the present invention. The particular embodiments and applications were chosen and described to provide the best illustration of the principles of the invention and its practical application to thereby enable one of ordinary skill in the art to utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated. All such changes, modifications, variations, and alterations should therefore be seen as being within the scope of the present invention as determined by the appended claims when interpreted in accordance with the breadth to which they are fairly, legally, and equitably entitled.
