Method for Decorating Ski Pole Shafts

The present invention is in the field of ski poles and more particularly in the field of methods for decorating the outer surfaces of ski pole shafts.

Most ski pole shafts are decorated with pleasing patterns and colors to make them more attractive to customers. The current trend is toward complicated and multicolored patterns, which has increased the difficulty and cost of applying graphic decoration to the shafts.

Aluminum ski pole shafts are typically painted. Paint, however, is prone to chipping and scratching. Applying several different colors also requires multiple passes during the painting operation, increasing manufacturing time and cost. It also requires relatively sophisticated painting machinery.

The recent popularity of composite fiber/resin ski poles has created demand for a new decorating method. Because the polymer resin on the surface of these poles reacts favorably with certain inks, it has become known to use silkscreen application of graphics onto the surface. However, multicolored patterns or graphics still require multiple silkscreening passes, and this is therefore less than an ideal solution to the cost and time problems associated with applying multicolored graphics to ski pole shafts.

It is also known to sublimate certain inks directly onto a substrate. However, prior art sublimation techniques are limited to relatively flat surfaces, and do not lend themselves to decorating the cylindrical shafts of ski poles. Additionally, the fibers (fiberglass, graphite, Kevlar.RTM., etc.) in the composite shafts do not accept coloring from sublimation inks.

The present invention is a novel method for sublimating graphics onto resin-surfaced ski pole shafts in an inexpensive, one-pass process. This novel adaptation of sublimation inking techniques to ski pole shafts reduces costs, allows for one-pass application of complicated, highly detailed graphics in multiple colors, and when applied properly provides a nearly chip-proof colored surface.

In general, the inventive method comprises the steps of forming a cylindrical sleeve of sublimation-inked paper with the desired graphics on the inside surface, inserting the ski pole shaft into the sleeve, and clamping the sleeved pole in a heated die to transfer the sublimation ink graphics from the paper of the sleeve onto the resin surface of the ski pole shaft.

In a preferred form, a set of matched top and bottom sublimation ink sheets, each including sublimation graphics to cover one longitudinal half of the ski pole shaft, are precisely fastened at the borders of the graphics patterns to form a pole-receiving sleeve or "cartridge". The pole is inserted in a close fit which, when clamped in a cylindrical heating die, precisely mates the two half-patterns onto the surface of the ski pole in a nearly seamless fit to cover the entire circumference of the ski pole shaft with the desired graphics pattern.

In a further form of the invention, each top and bottom pattern sheet is provided with multiple sets of sublimation graphics for multiple ski poles, and are subsequently fastened at the borders of the patterns to produce a sleeve capable of accepting a plurality of ski pole shafts at one time. Sleeves capable of holding up to twelve or more poles are possible, and are limited only by the size limitations of the heating die.

When the top and bottom sheets of the sublimation sleeves are fastened, typically by gluing, the sleeve is relatively flat. A further feature of the invention is the application of a removable, tapered guide tip to the pole to help guide it into the initially flat sublimation sleeve.

It has been found that sublimation works best on polyester or vinylester resins. While the resin surface of most composite ski pole shafts is suitable, the reinforcing fibers typically are not ink-friendly. In a preferred embodiment the graphics are sublimated onto a composite fiber/resin ski pole shaft using a polyester veil of the type disclosed, for example, in co-owned U.S. Pat. No. 5,265,911. The veil surrounds the filaments to ensure a resin-rich, ink-friendly surface for sublimation.

These and other features of the invention will become apparent upon further reading of the specification.

FIG. 1 is a perspective view of two spaced sublimation sheets as used with the method of the present invention;

FIG. 2 illustrates the sheets of FIG. 1 fastened together to form a sublimation sleeve used with the present invention;

FIG. 3 illustrates the step of inserting uncolored ski pole shafts into the sleeve of FIG. 2;

FIG. 4 illustrates the step of placing a sleeve filled with ski pole shafts into a heated die to transfer graphics onto the ski pole shafts;

FIG. 5 illustrates the heating die of FIG. 4 closed around the pole filled sleeve;

FIG. 6 schematically illustrates a finished pole removed from the sleeve; and,

FIG. 7 is a cross-section of a preferred composite ski pole shaft structure used with the present invention.

Referring now to FIG. 1, a preferred embodiment of the present inventive method is illustrated using pre-printed sublimation pattern sheets 12 and 14 provided as matching pairs. Each sheet is provided with a plurality of graphic half-patterns 16 printed in sublimation ink. In the illustrated embodiment, each sheet contains approximately twelve half-patterns 16 running lengthwise, each half pattern being a rectangular strip capable of covering a half-circumference of the length of a ski pole shaft with the desired pattern along its length. The sublimation sheets and the sublimation inks in patterns 16 are commercially available from different sources. The pattern itself can be designed by the user. In the illustrated embodiment, the sheets are purchased from Classic Print Products in Burlington, N.C., and use a commercially available sublimation ink available from Flint Ink in Flint, Mich.

Also shown in FIG. 1 are a number of parallel glue lines 18 which, in the illustrated embodiment, have been silkscreened onto sheets 12, 14 to mark the longitudinal boundaries or edges of each half-pattern 16. It will be apparent to those skilled in the art that glue lines 18 may be applied in any known fashion.

Referring now to FIG. 2, once glue lines 18 have been applied to sheets 12, 14, a suitable heat-resistant glue is carefully applied along the glue lines so as not to run over onto half-pattern 16. Sheets 12, 14 are then glued together to form a pole-receiving cartridge or sleeve 20 with a plurality of individual pole-receiving slots 22, in the illustrated embodiment twelve slots. The inside surface of each slot 22 comprises mated top and bottom half-patterns 16 (FIG. 1), each capable of covering half the circumference of a ski pole along its length.

Referring to FIG. 3, sleeve 20 is initially fairly flat when glued together. However, it is capable of receiving a ski pole shaft 24 in a snug, sliding fit such that the top and bottom half-patterns 16 conform closely to the surface of the ski pole shaft. Each sleeve 20 in the illustrated embodiment is capable of receiving up to twelve poles, although it will be apparent to those skilled in the art that sleeves can be built to accommodate almost any number of poles, from individual sleeves for an individual pole to sleeves with twelve or more pole slots.

Insertion of pole shafts 24 into slots 22 in sleeve 20 can be facilitated by the use of a removable, tapered guide tip 26 on the end of the pole to help open each slot 22 as the pole is inserted. In the illustrated embodiment tips 26 are formed from an inexpensive aluminum, and have a relatively smooth surface so as not to abrade the sublimation ink patterns on the inside of slots 22.

Referring now to FIGS. 4 and 5, a pole-filled sleeve 20 is next inserted into a mating clamping die 28, which includes a plurality of pole-shaped die openings 29 of a diameter approximating the diameter of pole shafts 24 in sleeve 20. In the illustrated embodiment the clamping die 28 includes twelve slots 29 to match the twelve-pole sleeve 20. Again, however, clamping die 28 may be built to accommodate a single pole, twelve poles, or as many as desired. Once sleeve 20 and its pole shafts 24 are in position, upper half 28a is lowered onto lower half 28b to heat the sleeve to a desired temperature for a time sufficient to transfer the sublimation ink to the surface of the pole shafts. In the illustrated embodiment the die is heated to approximately 415.degree. F. for 60 to 80 seconds.

After heating, the sleeve with the poles still inside is removed and allowed to cool for a short period of time, and then the poles are removed (FIG. 6). At this point the graphics transfer is complete, and each pole now has a permanent graphics pattern over its entire visible surface, transferred directly (by sublimation) from the interior surfaces of sleeve 20.

It has been found that the sublimation transfer works best with polyester or vinylester resins. It has also been found that the sublimation inks do not readily transfer to the carbon or other fibers located in the resin body of composite ski pole shafts for reinforcement. In view of these two factors, a preferred composite ski pole shaft structure has been determined for receiving graphics with the above-described process. Referring now to FIG. 7, finished pole shafts 24 comprise a resin body 24a with a large number of reinforcing filaments 24b (carbon, Kevlar.RTM., fiberglass, etc.) distributed in the resin in suitable reinforcing patterns. Filaments 24b are surrounded by a veil 24c, in the illustrated embodiment a polyester veil, which provides anti-splinter protection by preventing filaments from protruding through the resin surface of the ski pole shaft. Veils of this type are disclosed, for example, in co-owned U.S. Pat. No. 5,265,911. This polyester veil also produces a resin-rich surface 24d, without filaments, which is readily compatible with sublimation inks. Additionally, the polyester material of the veil itself is ink-friendly, and together they produce a superior and preferred pole surface for the sublimation process described above.

While the veiled pole of FIG. 7 is a preferred ski pole structure for use with the above process, it will be apparent to those skilled in the art that other pole shaft structures can be used with the present invention as long as a suitable ink-friendly resin surface is presented.

Referring to FIG. 6, the result of the sublimation process is a graphics pattern which literally embeds itself into the material of the ski pole shaft. In the illustrated embodiment, it has been found that the graphics pattern extends approximately 0.020 inches into the surface of the pole. This makes it exceptionally durable, chip-and scratch-resistant, and generally more permanent than graphics applied with prior methods.

Additionally, the entire process is less expensive than painting or silkscreening; the patterns initially pre-printed on the sublimation sheets can be as intricate, detailed and multi-colored as desired, and can still be applied with a single "pass" through the heating die; and, batches of poles, up to twelve or more at a time, can be produced with different colors or patterns in a single batch by providing alternating half-patterns on the sublimination sheets. For example, sheets 14, 16 in FIG. 1 could be provided with twelve half-patterns 16, each of a different color and/or pattern.

Although the sublimated graphics pattern is extremely durable, it is possible to provide a subsequent coating, for example a polymer clearcoat, over the sublimated graphics surface.

While the foregoing is an illustrative example of the invention intended to satisfy the requirements of 35 U.S.C. .sctn.112, it should be understood that variations and modifications of the above-described method for decorating ski pole shafts will lie within the scope of the invention as defined by the appended claims. For example, while the illustrated method has been described with the use of two matched, top and bottom half-patterns mated together from separate sheets to form a slide-insertion slot for the shaft, it may be possible to apply the pre-printed pattern in rolling fashion around the ski pole shaft, or in some other manner. Heating times and temperatures may vary depending on the inks and patterns used. It may be desirable to apply a pattern over only a portion of the ski pole shaft, rather than along its entire length.