Vehicle rim with printed graphics

Abstract

Rim (20) for a bicycle wheel with a center plane (CP), comprising: a tire engagement portion (24) located on the outer periphery of the rim; an inner peripheral portion (26) located radially inward relative to the tire engagement portion (24); a first side wall (28); a second side wall (30) spaced from the first side wall (28), wherein the first and second sidewalls (28, 30) extend between the tire engagement and inner peripheral portions (24, 26); a plurality of surface features (32) formed in the first and second side walls (28, 30); and a non-contact printed graphic disposed on one or both of the first and second sidewalls (28, 30), characterized in that the non-contact printed graphic is applied to the plurality of surface features (32) and substantially preserves the size and shape of the plurality of surface features (32), and wherein the surface features (32) are sized and shaped to create a turbulent surface layer as the wheel moves through the air to reduce drag.

Description

The invention relates to a rim for a bicycle.It has become common practice to apply various characters, images, terms and other graphics to bicycle rims. In the course of the widespread acceptance of high-profile rims by profibrus and amateurs, the manufacturers have recognized the "advertising" possibilities offered by such a large rim area.Bicycle rims, e.g., carbon fiber reinforced plastic (CFRP) bicycle rims, are increasingly being labeled, marked, or coated with conventional materials in a number of conventional methods. With respect to graphic marking of a rim, conventional methods typically provide a form of contact printing in which ink is applied to a shield film substrate of, for example, polyvinyl chloride, polyester, polyolefin, polycarbonate and / or cellulose (calendered wood fiber paper). The graphics are printed, for example, by screen printing, offset printing, thermal printing or inkjet printing. The printed substrate, on the back (i.e., the non-printed surface) of which a pressure sensitive contact adhesive is typically applied, is stamped to the appropriate shape and size to fit the rim as desired.A similar method of making a sign consists of a substrate consisting of a cured printed ink resin having a printed adhesive layer, applied to a coated paper or resin carrier film, and later removed by dipping the carrier / sign in water or a hydrocarbon solvent solution to remove the ink film from the carrier. The compact ink film is then carefully applied to the receiving member or object and thereafter lightly pressurized to remove most of the solvent, cured with heat, typically in an oven, to activate the adhesive and thereby bond the ink resin to the receiving substrate.Another conventional printing method for graphic marking of a rim without an intermediate substrate is known as pad printing. Pad printing uses a silicone rubber stamp or pad which transfers an ink form or image from a plate into which a graphic form is etched or engraved and then filled with ink and applied to the receiving member by contact with the rubber stamp.It is known that bicycle rims have uneven surfaces or surface features to achieve aerodynamic advantages. A CFRP rim is manufactured, for example, with a plurality of surface features in the form of "nipples", which have proven to be surprisingly effective in reducing the resistance value of the rim of a bicycle. Furthermore, the process of developing tools for the manufacture of CFRP rims with surface features may be expensive. Unfortunately, in commonly practiced printing technology, already existing surface features are obscured, which can significantly limit the effectiveness of the features.The current methods for industrial marking of a rim as briefly stated above have technical drawbacks, some of which are described below:• Printed label with pressure sensitive adhesive, i.e. a pressure sensitive label - probably the most widely used method of marking - the graphic image size can be limited due to the adhesion of the substrate; graphic forming is limited by the complexity of stamping the substrate; the substrate cannot perfectly conform to the non-planar surface features; the substrate has a considerable mass; the relative hardness of the substrate is detrimental to longevity; adhesive bonding is not permanent.• Solvent-applied shield, in which the adhesive is cured by drying - unsuitable for non-planar geometry; rim defects destroy the shield; long drying phase; must be applied manually.• Water-applied shield - topcoat required; improper for non-planar geometry; rim defects damage the substrate during the curing process; must be applied manually.• Direct screen pressure - Receiving surface of the rim does not allow this method if the rim is not sufficiently flat or smooth.• Direct pad printing - Large graphic area precludes application.• Laser etching - no colors possible; low contrast; large graphics too expensive.• Color sublimation of an offset printed image - by absence of the white pigment, the colors do not become visible.An example of a rim of the prior art is disclosed in document US 7 114 785 B2, which is directed to a "disc" wheel for a bicycle. The patent describes both a carbon fiber reinforced plastic construction and surface features. The side walls of the disc wheel are provided with surface structures, as can be seen in FIG. 17 of the document U.S. Pat. No. 7,114,785 B2. Radially inside the surface structures, a print is applied to the side walls, which print is thus arranged on a planar section of the side walls.Furthermore, WO 2005 / 100 050 A2 discloses a method for printing the flanks of racing tires for motor vehicles and the printing of a rim by means of inkjet methods.From the above listing, it can be seen that the application of graphics and / or surface features to bicycle rims, especially carbon fiber rims, can present a challenge when low cost, high quality permanent graphics are desired that do not adversely affect the function of the rim. Therefore, there is a need for a high quality printing method and system for printing bicycle rims. The invention fulfills this need. To this end, the invention provides a rim for a bicycle having the features of claim 1. Further developments of the invention can be found in the dependent claims.In view of the current need for an improved printed bicycle rim and method thereof, a brief summary of embodiments of the invention is presented. In the following description, which emphasize and set forth some aspects of the various embodiments, certain simplifications and omissions may be found. Detailed descriptions of a preferred embodiment suitable for one of ordinary skill in the art to practice and use the inventive concepts follow in later sections, but it should be understood that minor variations of these concepts are covered by the invention, and particularly such variations are within the skill of one of ordinary skill in the art.Ink jet printing is a relative new printing process which has gained importance in recent years, primarily thanks to advances in the field of ink technology and an improved method for applying and curing the ink. The invention is generally directed to the use of an inkjet printing mechanism to apply contactless printed graphics and / or surface features to an image receiving surface of a bicycle rim.The invention generally contemplates the application of ordered colors in the form of very fine droplets of ink to a bicycle rim by means of an electro-mechanical "ink jet" print head in a scanning motion (back and forth) along X and Y coordinates in a horizontal plane. The applied ink droplets may coalesce into a line and the lines may coalesce to form a film layer. The layers may further be added to pre-applied and cured layers to produce three-dimensional features and / or patterns.In addition, the invention contemplates the deposition of ordered colors in the form of very fine droplets of ink onto a bicycle rim by means of an electro-mechanical "ink jet" print head in a motion along X, Y and Z coordinates. This method rather minimizes the loss of accuracy and resolution that can occur when the ink is applied with the inkjet printhead and the receiving substrate is spaced greater than 6 mm apart.Simultaneously with or subsequent to the application of the ink, photopolymerization curing of the deposited ink occurs, which is activated by exposure to strong ultraviolet (UV) light. The applied and cured ink forms a thin, uniform, durable graphic film that resists adverse environmental conditions, i.e., scratches, abrasion, corrosion, washing, and sunlight, that occur during the life of the product. The means for curing the ink is not limited to UV curing.This method of ink application and curing has been found to be an effective means of applying single and multiple plies of resinous ink to a bicycle rim, particularly, for example, ZIPP® FIRECREST® rims, whose sidewalls are relatively flat and parallel over a substantial span. Moreover, since this ink application method does not contact the receiving surface as was required by the prior application methods, it is highly accurate to apply a coating, whether graphic or otherwise, to a non-planar surface, applying a uniform layer of desired thickness, with the surprising result that the shape and size of already existing features on the surface are maintained with precision, which is not readily achievable with other known techniques.While ink jet printing is suitable for applying a thin and uniform film thickness, it may also be used to selectively apply and bond multiple plies of ink to the rims by numerical control, thereby creating the desired three-dimensional geometric patterns or shapes on the rim surface. This provides an effective means for optimizing the size, shape, and amount of surface features applied to the rim surface that can reduce the surface resistivity of the rim. Inkjet printing can also provide other types of desirable rim members and advantages.Within the scope of this disclosure, it is understood that surface features include all three-dimensional elements that are already present features of the rim and / or three-dimensional elements that are applied to the rim by means of inkjet application. By applied features is meant all elements added to the rim by inkjet application - including graphics, three dimensional elements that could have the form of surface features, and uniform layers of material.Another benefit of this application method and its inherent efficiency allows the omission of the adhesive backed substrate used in conventional methods. By omitting the substrate and only applying the ink to the rim, a conservatively estimated weight saving of over 30 grams can be achieved. The omission of the substrate and the processing steps, e.g. punching, reworking and assembly, which follow a conventional printing process, results in cost savings of over 90%.Further, the same printing method can be used as a means for selectively precisely coating a bicycle rim with a protective layer (varnish), which is not achievable with conventional methods. An example of this would be to coat a recessed opening or feature that serves as a wear indicator of a brake track pad of a wheel rim. Existing practice provides multiple steps and a particular order of operations, making the manufacturing process significantly more cost and time consuming.Furthermore, contactless printing inherently prevents the application of lateral loads-outside the plane-to planar FRP surfaces designed to accommodate loads in the plane.A further development of the invention provides a wheel rim for a bicycle having a central plane including a tire engaging portion on the outer periphery of the rim. An inner peripheral portion is located radially inward relative to the tire engagement portion. A first sidewall and a second sidewall spaced from the first sidewall extend between the tire engagement portion and the inner circumferential portion. A plurality of surface features are formed in the first and second sidewalls, and a non-contact printed graphic is disposed on one or both of the first and second sidewalls, the non-contact printed graphic substantially preserving the size and shape of the plurality of surface features.The surface features are sized and shaped to form a turbulent surface layer as the wheel moves through the air to reduce drag. The non-contact printed graphic can be applied with an ink jet printer. The rim includes an image pickup surface on the first and second side walls, the image pickup surface being within 30° parallel to the central plane of the rim, and the contactless printed graphic is disposed on at least a portion of the image pickup surface. The image pickup surface may be generally parallel to the central plane. The image-receiving surface may be at a distance of less than about 6.5 mm from the contactless application means.Another aspect provides a wheel rim for a bicycle having an axis about which the wheel rotates and a center plane perpendicular to the axis with a tire engaging portion on the outer periphery of the rim. An inner peripheral portion is located radially inward relative to the tire engagement portion. A first sidewall and a second sidewall spaced from the first sidewall extend between the tire engagement and inner circumferential portions. On each of the first and second side walls there is an image pickup surface, each of the image pickup surfaces extending within 30° parallel to the central plane of the rim, and a contactless printed application feature is arranged on at least a part of the image pickup surface.Other embodiments provide a rim as claimed wherein the contactless printed plot feature includes a graphic. The non-contact printed application feature may include a surface feature and / or a uniform film. The image pickup surface may be generally parallel to the central plane. The image-receiving surface may be at a distance of less than about 6.5 mm from the contactless application means. The rim may be made of FRP.Another aspect may also provide a method of forming surface features on a wheel rim, including the steps of providing a wheel rim having a tire engaging portion on the outer periphery of the rim, an inner peripheral portion radially inward of the tire engaging portion, a first sidewall and a second sidewall spaced from the first sidewall, the first and second sidewalls extending between the tire engaging portion and the inner peripheral portion, and applying one or more layers of material to the wheel rim with a non-contact printer in a selected pattern to form a plurality of application features on the first and second sidewalls. Further, an aspect may provide a method of applying graphics to a wheel rim, including providing a wheel rim having a center plane, a tire engaging portion on the outer periphery of the rim, an inner peripheral portion radially inward of the tire engaging portion, a first sidewall, and a second sidewall spaced from the first sidewall and extending between the tire engaging portion and the inner peripheral portion, and applying ink to the first and second sidewalls at an application angle within about 30° parallel to the rim center plane with a non-contact printer. FIG. 1 shows a rim for a bicycle wheel with surface features; FIG. 2 shows a system for contactless printing of rims for a bicycle wheel; FIG. 3 shows the bicycle wheel of FIG. 1 illustrating an image pickup surface of the rim; FIG. 4 is a diagram of a printhead assembly having a plurality of printheads and light sources; FIG. 5 is a diagram generating various application shapes; and FIG. 6 shows a plurality of methods for contactless printing on rims.Embodiments of the invention will now be described with reference to the drawings. The words "first / r / s" and "second / r / s", "front / r / s" and "rear / r / s", or "left" and "right" are used for clarity only and not for purposes of limitation. Moreover, the terms refer to bicycle mechanisms conventionally attached to a bicycle, wherein the bicycle is oriented by default and used unless otherwise specified.FIGS. 1 and 3 show an embodiment of a rim 20 for a bicycle to which a contactless printed graphic can be applied. The rim 20 includes a tire engaging portion 24 at the outer periphery of the rim, an inner peripheral portion 26 located radially inward of the tire engaging portion, and a pair of side walls 28, 30 extending in the radial direction between the inner peripheral portion and the tire engaging portion and forming the sides of the rim. In the illustrated embodiment, a major portion of the sidewalls 28, 30 are parallel or substantially parallel, i.e., within a few degrees of deviation from parallelism, to the centerline or center plane CP of the rim. In one embodiment, the larger portion of the sidewalls 28, 30 forms the image receiving surface of the rim.The sidewalls 28, 30 may include a plurality of surface features 32 designed to create, e.g., a turbulent boundary layer to reduce the drag of the wheel as a wheel with the illustrated rim moves through the air. Alternatively, the sidewalls 28, 30 may be free of surface features. The surface features 32 may be positive or negative features (i.e., protrusions or recesses) with a ridge that is offset relative to the planes of the sidewalls 28, 30 of the rim 20. The surface features 32 may be designed to create a turbulent boundary layer as the rim 20 moves through the air to reduce drag. As mentioned above, the surface features 32 may also include wear indicators.FIG. 3 shows an image recording surface 22 of the rim 20, which is also denoted by 21. The image receiving surface 21, 22 may be considered to be the surface of the rim to which an ink jet printer can apply ink in the desired manner. In an embodiment where the inkjet printer head (see FIG. 4 ) moves along X-Y coordinates, the image pickup surface 21, 22 may be considered to be the surface of the rim 20 no further than about 6.5 mm from the inkjet printhead. In practice, the ink jet printhead may be positioned about 1.5 mm from the portion of the rim closest to the printhead (see Figure 4). In the drawings, CP defines a central plane of the rim. The portion of the rim closest to the printhead in Figure 3 is indicated at 34, which corresponds to the laterally outermost distance of the side walls 28, 30 relative to the central plane CP. As the curvature of the rim extends away from the outermost distance 34 and inwardly toward the central plane CP of the rim, the distance of the printed surface of the rim from the printhead becomes greater, i.e., greater than 1.5 mm. For example, if the distance between the print head and the printed rim portion exceeds about 6.5 mm, the printing accuracy may deteriorate and therefore the portion of the rim exceeding the distance indicated by 22 cannot be considered as the image pickup surface 21, 22. For purposes of this disclosure, the distance 22 is referred to as a contactless deposition distance. In one embodiment, the contactless deposition distance should be less than about 6.5 mm.It is natural that, when the print head can be moved vertically, the image pickup area of the rim on which ink can be accurately positioned is maximized, and also that the application accuracy of various ink jet apparatuses can be higher or lower.The angle of the surface of the rim 20 that receives the applied ink may also affect the quality of the applied graphic. The ink is directed onto the rim in a direction of application DD which is generally perpendicular to the central plane CP when the rim 20 is held in the tool 40. The ink impinges on the rim 20 at an angle which may be referred to as the application angle. In this application, if the ink is applied at an angle perpendicular to the surface of the rim 20, the application angle is considered zero (0). A graph plotted on the rim 20 at a zero plot angle is not distorted. Graphic material deposited on rim 20 at a deposition angle greater than zero is distorted in proportion to the deposition angle. Therefore, in one embodiment, the image pickup surface 21, 22 can be considered to be the surface of the rim where the application angle is less than about 30°. An area of the rim 20 in which the application angle is greater than approximately 30° due to the curvature of the rim entails the risk of unduly distorting graphics depending on their specific design.FIG. 2 shows a printer system 36 for contactless printing of rims for bicycle wheels. The printer system 36 includes a generally planar horizontal bed 38 defining the receiving area for the rim 20 and a printhead housing 44 positioned above the bed.Referring now also to Fig. 4, the printer system 36 includes a printhead housing 44 having a plurality of inkjet printheads 45, which may be piezoelectromechanical devices. The ink jet printheads 45 apply a predetermined volume of ink droplets on demand when driven by an electrical pulse. The inkjet printheads 45, which may be between one and eight in number per ink, for example, are moved across the bed in a back and forth scan motion by a bridge 46 that moves the inkjet printheads along controlled X and Y coordinates. In an alternative, the inkjet printheads move along controlled X, Y, and Z coordinates.The system's ink jet printheads 45, typically controlled by raster software, drop a series of droplets of the ink in very precise amounts ranging from 1 to 300 picoliters onto the rim 20 to apply a collection of droplets in one or more layers in ordered color. For example, the application of the ink builds an image, shape, or stripe to render the appearance of the original electronic image template file.The printer system 36 includes one or more light sources 48 disposed on or within the printhead housing 44. The light sources 48 are typically mercury ion arc lamps having a spectral power of 350 to 450 nm to cure the applied ink. Shutters 50 may also be provided as part of system 36 and positioned to control each light source 48.The inkjet printheads 45 may be disposed within the housing 44 in any suitable manner. In one embodiment, an ink jet printhead is arranged that sequentially contains a base ink 45P, a white ink 45W, and a black ink 45B. In addition, ink jet printheads 45C of different colors may be arranged to apply ink after the black ink 45B. Further, the inkjet printheads may, for example, print transparent glossy or matte coatings 45OC over the previously applied ink layers or as a single protective layer on the substrate itself.The bed 38 may include a retaining tool 40 that is a portion or additional device of the bed and is sized and shaped to receive and retain the rim 20. The holding tool 40 may include a circular recess. The holding tool 40 may include a vacuum chuck or other means for releasably securing the rim 20 in position on the bed 36. The bed positions the rim 20 vertically and horizontally so that the rim is within a desired contactless distance from the printheads 44 and so that ink is applied at the desired positions on the rim. The desired optimal distance from the printheads 44 to the outermost region 34 of the rim 20 may be about 1.5 mm. It will be appreciated that the optimum deposition distance from the printhead to the sidewall surface will depend on the particular ink jet system employed.The printer system 36 includes conventional control circuitry 52 for controlling the mechanical and electrical components of the system, which may also convert the image data file sent to the system to such a form that the system may print the image or images.In operation, the printer system 36 is typically electronically supplied with a "master" file, e.g., one or more digital images consisting of shapes that are or have been converted into a raster image of dots or pixels.During operation, the printer system 36 applies an ink resin, which may be a UV curable ink matrix. The ink may consist primarily of acrylic monomers with a curing (i.e., catalyzing or polymerizing) initiator component. After application, the ink is cured under strong UV light from the light source 48. The advantage of UV curable inks is that the ink is "dry" once cured so that UV curable inks can be applied to a wide range of uncoated substrates, with the result of a very robust image or coating. The ink is formulated with a surface tension compatible with the substrate, which is well known in the ink formulation art.Once the ink has been applied to the substrate (rim 20), it must be cured, i.e., converted from liquid to solid, by chemically bonding to the target position on the rim and developing adhesive and cohesive strength that provides the durability needed for the conditions encountered in use.The ink contains photoinitiators that absorb the UV energy from the light source 48. During the irradiation, a chemical reaction takes place which converts the liquid printing ink into a solid film. The ink contains monomers which function as solvents because of their ability to reduce viscosity and combine with other ink components. Thus, the ink compositions are 100% solids and do not release volatile organic constituents (VOCs). Monomers also contribute to improved film hardness and resistance standing properties. The ink also contains oligomers that determine the final properties of the cured ink film, including its elasticity, outdoor performance and chemical resistance. The dyes of the printing ink can be dye-based or pigment-based. Normally, they are pigment-based because of the higher light fastness and durability of the pigments compared to dyes. Pigments used in exterior advertising and for display applications have similar requirements as for motor vehicle lacquers. Consequently, some overlap occurs. While a pigment is chosen based on the application required, size control and reduction, together with that of the dispersion technique, are important items in ink formulation.The ink is exposed to UV radiation, thereby causing a chemical reaction to take place. The photoinitiators effect the crosslinking of the printing ink constituents to form a solid. Typically, a mercury vapor lamp 48 is positioned on each side of the printhead and is sealed to generate a large amount of heat, although the heat is not involved in the curing process. A sealed mercury vapor lamp 48 is used for UV free radical ink used in the majority of the flat bed ink jet systems.UV cured inks do not evaporate but cure as a result of this chemical reaction. No material evaporates or is lost, meaning that 100% of the amount applied benefits the coloration. This reaction proceeds very rapidly, resulting in almost immediate drying and resulting in a fully cured graphic within seconds. This enables a rapid printing process. As a result of this almost immediate chemical reaction, no solvent will permeate to the substrate once the ink has been applied thereto, enabling fully opaque and saturated prints.Figure 5 shows a simplified version of the rim 20 and an ink jet print head 45 which can apply ink 60. Depending on where the plot of each ink is positioned relative to other plots, the ink on the substrate may take a variety of forms and be arranged as a graphic (e.g., images and words) and / or non-graphic plot. For example, a single dot 62 of the ink 60 forms a discrete dot of the ink. When multiple dots of ink 60 are applied in a continuous line or in closely spaced dots, the ink forms a discrete line 64 When multiple lines of ink 60 are applied parallel and sufficiently close to each other to coalesce, a two-dimensional layer or stripe 66 is formed. The thickness of the strip 66 depends on the number of lines applied. When the ink 60 is applied in perpendicular layers, a three-dimensional application feature 68 may be formed. It will be appreciated that the application of ink is seen as an application feature regardless of whether the feature is a thin graphic or a relatively three-dimensional feature. In this manner, the inkjet printer system may serve to make a rim with surface features formed by inkjet printing after the manufacture of the rim from a smooth rim substrate, or alternatively, the application features may form, for example, additional surface features on a rim with already existing surface features formed during the manufacture of the rim. The complexity and size of the application features 68 are limited only by the ability of the inkjet printer system 68 to apply the ink.Application features 68 are therefore to be understood as meaning all features and / or surface features which are produced by a contactless application method.FIG. 6 is a flow chart with three methods for contactless printing of bicycle rims. It should be appreciated that some steps may be performed in a different order than that illustrated. As is well known, a print master is sent to the printer system 36 in step 102 and converted to a form usable for the system. The print template may be in the form of a graphic and / or in a non-graphic form. A rim 20 is positioned on the printer system bed 38 and in the holder tool 40 in step 104. The rim 20 is secured by the retaining tool 40 in step 106.In step 108, a determination is made as to whether or not the rim has surface features. If the rim 20 has existing surface features, ink may be applied to form a graphic in step 110. If the rim 20 does not have surface features, a determination is made in step 112 as to whether surface features are to be formed by contactless application. In step 114, the system 36 may be used to form application features 68 in the form of surface features, as well as to form graphics during or after the formation of the surface features. If no surface features are desired in step 116, the system may print graphics and / or apply a protective film, for example, in step 116.After or simultaneously with the application of graphics and / or surface features, the printing ink is cured in step 118 by irradiation with UV light. Once all of the ink has cured, the rim is released from the holding tool 40 and removed from the printer bed 38 in step 120.

Claims

A rim (20) for a bicycle wheel having a center plane (CP) comprising: a tire engaging portion (24) located on the outer periphery of the rim; an inner peripheral portion (26) located radially inward relative to the tire engaging portion (24); a first sidewall (28); a second sidewall (30) spaced from the first sidewall (28), the first and second sidewalls (28, 30) extending between the tire engaging and inner peripheral portions (24, 26); a plurality of surface features (32) formed in the first and second sidewalls (28, 30); and a contactless printed graphic disposed on one or both of the first and second side walls (28, 30), characterized in that the contactless printed graphic is applied to the plurality of surface features (32) and substantially preserves the size and shape of the plurality of surface features (32), and wherein the surface features (32) are sized and shaped to create a turbulent surface layer when the wheel moves through the air to reduce drag.The rim (20) of claim 1, wherein the contactless printed graphic is applied with an inkjet printer (36).The rim (20) according to any of the preceding claims, further comprising an image pickup surface (21, 22) on the first and second side walls (28, 30), wherein the image pickup surface (21, 22) lies within 30° parallel to the central plane (CP) of the rim (20), and the contactless printed graphic is arranged on at least a part of the image pickup surface (21, 22).The rim (20) of claim 3, wherein the image pickup surface (21, 22) is generally parallel to the central plane (CP).Rim according to claim 3 or 4, wherein the image recording surface (21, 22) is arranged at a contactless application distance (22) below about 6.5 mm.The rim (20) of claim 4, wherein the plurality of surface features (32) and the contactless printed graphic are disposed on the image receiving surface (21, 22).The rim (20) of any preceding claim, wherein the rim is made of FRP.

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