US2038530A - Laminated ski and the process of making the same - Google Patents

Description

R. C. ANDERSCN April 28, 1936.

LAMINTED SKI AND THE PROCESS QF MAKING THE SAME' Fiied uayfla, 1933 l .v N\ NV N, .m mm 4 Am. ww. .S nl 'a n 1| .L NQ? Am Am vw. .v m

Patented Apr. 2s, 193el UNITED STATES PATENT oFElcE LAMINA'ED SKI AND THE PROCESS 0F MAKINGv THE SAME -5 `Raymond C. Anderson, Seattle, Wash. Application May 13, 1933, Serial NoI 670,899 12 Claims. (Cl. 208-184) My invention relates to the art of skis, and to the process of making the same. More particularly, vmy invention relates to a laminated ski characterized, among other features, by the precision of magnitude and location, longitudinally considered, of the degree of spring embodied in the ski, the flexibility and capacity to resist side thrust of the upturned tip portion of the ski, and bythe precision of weightV of eachl ski, and its form retaining feature.

The exceedingly high velocities attained while skiing, create tremendously high strains upon the ski. Thevelocities reach as high as sixty miles per hour, and even higher on jumping take-offs, the weight of a skier may be more than two hundred pounds, and the vertical distance through which he may drop may be fifty feet or more. slopes and inclines prevail, hidden obstacles in the snow, in the form rocks, fallen logs, or other solid obstructions may put exceptionally high strains upon the skis, and unless they are equal to the ensuing shocks, severe injury may occur to the skir.

In manufacturing skis, the common practice heretofore has been to make them of a solid piece of wood, as hickory, ash, pine or birch. It is well known that hickory forms one of the best species of wood for use as a runner. However, the grain of hickory wood is very irregular, and its density is subjected to quite wide variations. Skis made from a single billet of'such woods warp, even after a little service, and as a consequencatheir usefulness is very seriously impaired, if not 'destroyed. Such skis warp even while held in stock before selling. Such warping is due to their being subject to severe strains and extreme changes in. climatic conditions, and especially to the necessary curves, bends and variationin thickness of the wood at different points. The curvatures characterizing the ski are imparted to the ski by steaming and molding or shaping the wood, and this puts the wood cells of the solid wood ski on one side under tension, and the cells on the oppositeside under compression. When the ski becomes wet, the compressed cells expand, and this expansion force gradually operates to deform the ski. i. e., spiral twisting both sidewise and `vertically. The top and sides of the ski may be painted. varnis'ncd, or otherwise coated to exclude water, but the bottom cannot be so protected. Its surface must be left free to function as a runner The usual waxing employed to afford s'now gripping action, becomes scratched, and in general 'touches the plane at the rear,

In cross-country skiing, where steepV provides very little protection against the'absorption of water. Hence, no substantial protection attains in the ski as heretofore commonly made.

It will be understood that the ski throughout. 5

most of its length is slightly arched, so that without any weight applied a small section of the ski and a small section touches the plane in front. Then when the weight of the skier is placed on the ski, the ski is depressed so that it touches continuously from front or upturn to rear or heel, thus providing a dependable even support or uniform full bearing throughout the snow contacting length of the ski.

The stiffness of the spring preferably should 16 gradually increase as the middle of the arch, or foot-rest portion, gradually approaches the plane, so that said middle portion does not pass below the horizontal plane. Any such sagging of the local section supporting the weight, i. e., the foot- 20 rest section, creates a brake action and lessens the weight support bearing. This condition emphasizes the importance of the ski retaining the form initially imparted. nate heel drag.

It is highly important to control the degree'of spring, and it is equally important to provide the same degree of spring in both members -of a pair of skis. This is very diiicult where the ski is formed from a. single piece of wood. Some skiers prefer to have a greater stiffness in the arch from the foot-rest rearward, than from the foot-rest forward. Moreover, portance portion of the skiparticularly springy, in order to promptly yield to a slight obstruction and move upwardly to lead the way for the rest of. the

ski to follow over the obstacle with the minimum the skier. While great flexibility is o and the ski embodying my invention readily pro- 50 vides for the required degree of lightness, and

' greater arching for flexibility, as well as strength.

On the other hand, a ski to be used for jumping must be broader, longer and heavy (fourteen or more pounds-the amount varying greatly) and 55 It is important to elimithere is the further imof having the front or tip or turned-up shaped as desired, and is placed in stock for sale. Y

a great -deal of further work is often necessary in rebalancing and reforming the skis in order to bring the sh back to true form, since twarps while being retained in stock for sine. This is true even inthe best gradeof skis. Accordingly. the manufacture ofthe sh is not done when the sh is oifered for sale, if it is to be retained in stock for any length of time. Often there is a great` deal of work involved in pairing shs to endeavor to'ilnd two that match in shape and weight and degree of "springiness and ilexibility of the tip portion. f

Furthermore, in mahng shs out of a solid wood billet, serious objection obtains to the waste of material, due to the fact that a given billet may 36 appear clear grained on the top and bottom, and

yet when the necessary cutting away and channeling is done, .knots will be encountered within the body of the billet. Often these are of such a size that the whole billet must be discarded. "I'husjnot only is the cost of the billet lost, but the work that has 'theretofore been performed in shaping that billet. In making the skis of my invention, we are enabled to use such portion of the billet as do have the clear grain, and thus avoid the waste of the expensive wood. As a result, we are enabled to obtain four or ve times as many shs out of a givenquantity of wood as is now done where a solid wood ski is made. A defective billet may provide four or live laminations,v

while it would be whollydisqualied forl use -as for making a solid wood ski.

The primary purpose of my invention is tov overcome all of the various diiiiculties above set forth, and to provide for the various requirements mentioned, as well as to provide a sh that may be economical in construction.

'I'he above mentioned general objects of my invention, together with others inherent in the same, are attained by the device, illustrated in the following drawing, the same being preferred exemplary forms of embodiment of my invention, throughout which drawing like reference numerals indicate like parts:

Figine 1 is a planv view of a ski embodying my invention;

liig. 2 is a longitudinal view in vertical section l on dotted line 2--2 of Figure 1;

Fig. 3 is a view'in cross section on dotted line V3-3ofFigure1;

Fig. 4 is a view in cross section on dotted line I-I of Figure 1;

Fig. 5 is a. view in cross section on dotted line embodying my invention, showing different colors of wood of different laminations in the channeled out portions.

A piece of wood well suited to serve as a runner, such as hickory, is cut in two to provide tworelatively thin laminations I and II,-I0 serving as a rimner lamination, and II as a cover or` top lamination which has a flat foot-rest section I2 and a tip portion comprising (a) the turned lup bend and (b) the point sections, I3 and I4, respectively. The lines of cut of the bottom and top of the runner I Il 'are parallel, and are straight longitudinally of the grain. A core or centrally disposed lamination I is prepared relatively thick in the ilat section I2, from which it tapers towardseach end, preferably feathering out at I3 and I 'I, and preferably becoming thicker at the heel section I6. The line of the underside cf the core lamination I5 is 4cut straight longitudinally of the grain, and the top is cut to taper as described above. The core has edges I8 and I9 cut rectilinear, so that it forms a trapezoid, Fig. 7. When bent to form in the assembly, the spring arch, the edges I8 and I9 are given a curved contour as shown in dotted lines .20 and 2l, respectively. In the tip portion, a short wedged shaped core member 22 may be inserted, which strengthens the point, and as it introduces a different curvature to the top lamination, it functions to increase the mutual support of the runner and top lamination in maintaining the curved form of the tip,on the same principle `as hereinafter explained, where the top surface of the core has a sharper degree of curvature than the spring arch.

Cut-out channels 23 and 24,Y 25 and 26, for` the ridge type of sh which may feather out towards the end portions of the sh, may be provided to lighten the ski and to provide for progressively greater iiexibility as the end portions of the skis are approached. These channels also function to throw oif much of the snow which otherwise would pack beneath or in front of the foot-rest section I2. A central longitudinal recess 2I is cut in the runner I0 to enable the ski to grip the snow and keep the ski running true.

In making the ski of my invention, the runner III, core or holder I5, cover II and wedge 22 are assembled in position after suitable waterproof glue is applied to the surfaces to be glued. .'I'op lamination II has its grain similar to that of lamination I0, and hence to neutralize the stresses, the piece II is des'irably turned end forend and with the sides reversed, as compared to the grain of runner II. This is preferably done unless a top lamination is' used from a diierent log or billet. The assembly is then placed in a gluing form, preferably without any steaming, and sprung above the horizontal plane 28 to form the spring arch 29. While steaming is preferably omitted, however, when certain species of wood and/or thickness ofwood laminations are employed, the steaming or heating may/necessarily be employed. The assembly is thus held under pressure while the glue is setting.

In the modied form shown in Fig. 8, a core is made up separately of a plurality of laminations 30, 3|, and 32. The various species of wood employed may be of different color, and some may have the grain running transversely oi the length of the ski. Maniftly, when the cut-out channels 23, 24, 25, and 26 are formed, the edge portions (Fig. 9) of the various colors of wood would appear and would provide a very attractive appearing ski, as well as provide for great strength. The core thus built up, with its particular degree of arch, would be preformed as a separate unit, and then the runner and top laminations would be applied thereto in the regular shaping form.

The mode of operation of the ski structure. embodying my invention is as follows:

Much in this respect will be understood from the description above given.

The arch 29 is important toprovide spring, so that when the weight of the operator is applied it will depress substantially to the horizontal plane 28 but not below it. By having the upper side of the runner I and the under side of the core l cut with the grain and straight longitudinally, it is manifest that the core l5 is placed under compression when the assembly is arched. The core |.5 may be regardedas functioning as a spring of the arch form for the rimner l0, said runner resiliently holding the core in an arched form. The glue line between the runner l0 and the core l5 operatesas an impervious barrier to moisture migrating through the thin runner lamination I0 to deform the arch. The maintaining of the spring of the ski of my invention is dependent upon the relatively thin laminations adhesively bound to the core member. By controlling the degree of tapering of core l5 rearward as compared to that forward provides for the proportion of spring to be locatedrearward'of footrest section 4l2 as compared to that located forward of said section. Some prefer to have greater stiffness rearward, and my invention provides for this, s o that greater flexibility forward permits the better overcoming or overriding of obstacles or unevenness of the snow surface. It will be understood that the underside of the runner I0 is unprotected, so far as a` waterproof coating isconcerned, i. e., has no varnish coating to keep out water. Any coatinginitially applied is subject to being Aworn off promptly in use. While the underside of the runner is waxed, this is subject to being scratched,- and falls far short of preventing the runner from absorbing moisture.

While it is preferable to provide the ski with a top lamination having the same character of wood as obtains in the runner, so that thereby there may be a better neutralizing or balancing -of forces or stresses which are set up in the wood laminations, such is not necessaryonly two laminations, the runnerand a core, may be employed, or when a top lamination is provided, it may be of a different character of wood than the runner.

Obviously, this spring arch 29 is resiliently maintained by the mutual interaction of two. adjacent laminations-held together by the binder means. Having been bent to form the spring arch and then bound together while so bent, two adjacent laminations cannot be deprived of their -arch form without a relative movement between their adjacently disposed surfaces and this movement is prevented by the binder. The elongation of the ski, occurring when the arch is depressed,

would seem -to be derived from the elasticity of the wood fibers. 1

The lamination I5, above the runner Ill,v which ordinarily will be the core, is not subject to being softened by absorbing water, and as it, again ordinarily, will be relatively thick as compared' to the runner, it may well be deemed to be the spring providing element of the runner. With the'cover or superimposed lamination on the core or lamination next to the Irunrer, the core would .degree of curvature.

be further held to the arch form by the mutual position or relation of the core and this top lamination, so that then in a three plyv or lamination construction, the core could be regarded wholly as anarch spring member.

, Continuing this analysis, itis manifest, where three plies are present, that by providing the top surface of the core with a sharper curvature than that of the arch, that greater relative movement of the laminations, top and core, would be required than between the underside ofthe core and the runner which may have the spring arch 'Ihis difference in curvature particularly provides for a considerable augmenting of the force to depress the arch as it approaches the ho Vzontal plane; in4 other words, such an arch particularly stiffens as it approaches the horizontal plane.

The ski thus presents a particular problem, one side being unprotected against the absorption of moisture, while the top side, not subject to wear, may be coated with varnish, paint or other substantial coating whichwill prevent the absorption of moisture to a very large degree.

The unbalanced internal strains in solid wood,

or more laminations of wood in gluing shaping forms to produce the particular shape desired, each lamination being of the particular type or species of wood designed to perform the particular function required in the ski. laminations provide for advantages in. weight, spring, strength and water exclusion as follows:

In providing experienced in the solid wood ski, becausel it is limited by the character of the wood used. It is quite necessary that the running surface of the ski be of a strong, hard and tough material which ordinarily is found only in the rather heavy species of wood. The laminated ski of my invention can be so constructed as to use'only thin layers of the heavy vmaterial for the running 'surface, while the core may be o f a layer of lighter or heavier material as the particular type of ski may require. One of theprincipal requirements of a racing ski is that it should be very light without sacrificing strength, of ski should be very heavy to provide steadiness, but yet have all the life or spring of 'a lighter ski. The element of control of weight, which is highly desirable, can primarily be accomplished by the proper selection of material used for the core. Further, a pair of skis can be 'more equally balanced as to weight in my type of ski, due to the fact that the core material may be a wood witch does not vary in Weight, to the same extent as other woods necessary in the solid type. Hickory with -all'its advantages, is particularly lacking in uniformity of density, and grain structure.v By using a wood for a core of more uniform character, such variations are avoided.

As to providing springe-In the solid wood type of ski, as skis are now commonly made, it is practically impossible to obtain the same degree of spring and flexibility in both members of a pair,

vas there is a wide`variation in grain character .the proper weight, difliculty is to maintain and v The various while the jumping type i degree of exibility can be located at the most desirable point longitudinally considered of the ski.

As to strength, the laminated ski of my invention will withstand considerable more flexing and side thrust at the tip than the solid type, because thestrengthof wood is greatly increased when multiple layers are glued together. Thus, I am able to provide in the turned-up front portion of vne;

coming the deforming effect due to the absorption of water -by the interposition of water bar- .riers in the form of the waterproof glue line,

while the spring arch 29 is provided by protected laminations. vIn this wise, the water may be excluded, and its migration denitely limited and substantially kept away from that 'part of the ski which has the function of holding or maintaining the arch form.

Obviously, changes may be made in the forms, dimensions, and arrangement of the parts of my invention, Without departing from the principle thereof, the above setting forth only pre- A ferred forms of embodiment.

I claim:

1. A ski embodying a runner lamination having its top surface cut with the grain substantially in a straight plane longitudinally considered, a core lamination prior to assembly cut in the form of a trapezoid longitudinally considered, a cover or top lamination, said runner, core, and cover laminations being bent to Yform a spring arch, and a binder between said laminations, whereby the ski is resiliently held in the arch form with respect to a horizontal plane and the degree of spring in different portions of the ski longitudinally considered'may be determined.

2. A-'ski embodying relatively thin runner and cover laminations, and af relatively thick core `lamination of a species of wood having a different specic'gravity than the runner and'cover laminations whereby'the precise'weight of'a ski may be controlled, said core lamination being held in operation in a spring arch form longitudinally of the/ski by said runner and cover laminations.

3. A ski embodying anarched runner and a core member lamination, a waterproof glue line therebetween, said core member lamination being under compression longitudinally considered while resiliently held by said runner lamination in an arched positionwith respect to the horizontal plane.

waterproof adhesive means holding said. laminations in assembled form, whereby a relatively highly flexible vertically upturned portion is provided and at the same time one capable of sustaining severe side thrusts.

5. A ski embodying an arched rimner laminaation having an upturned front portion, a core and a cover lamination, the runner and cover laminations being relatively thin and of substantially the same length, the core being relatively thick and tapering towards the tip and heel portions of the ski, the heel end portion becoming thicker after tapering to provide` a strong heel portion, the tip portion of which core terminates about at the point of upturn, thereby providing for the upturned portion to consist of the runner and cover laminations; and a wedge shaped member in the top part of the upturned portion.

6. A ski embodying a runner lamination having its top surface cut substantially in a straight plane longitudinally considered; a core lamination with its under surface cut substantially in a straight plane longitudinally considered and its top side cut in an arc convexly curved with respect to said underside; a cover lamination for said core, said runner, core and cover lamination being bent to form a spring arch, the top surface of the core when bent having a sharper degree of curvature than the degree of curvature of the spring arch; and a waterproof glue means operatively disposed between said laminations, whereby the spring is substantially stiffened'when the arch upon being depressed approaches the horizontal plane. l

'1. The process of making a ski comprising the steps of cutting a relatively thin runner lamination; cutting a core member relatively thick in its central portion in comparison to the thickness of the runner lamination member; assembling said core member in superimposed position upon said runner lamination member with a layer of water-:proof adhesive therebetween, said assembling being done while the said laminations are bent in an arch form with the runner lamination member being disposed in an arc of shorter length than the arc of the top of the core member; and subjecting said assembly to pressure while the veneer is setting.

8. A ski embodying a runner member lamination and a core member lamination, said laminations being adhesively bound together, said core lamination being relatively thick in the central portion longitudinally considered and tapering towards the end portions, said runner lamination being relatively thin in comparison to the central portion of said core member, the mutual interaction of the core member and runner laminations through the adhesive operating to provide and maintain a spring arch form in the ski longitudinally thereof.

9. In a ski, a core member distortedly held to form an arch spring longitudinally of the ski by a lamination adhesively bound to said core member.

10. A ski embodying a spring core member having an arch form longitudinally considered; a relatively thin runner lamination having a portion disposed in an arc paralleling the arc of the under side of the core member; anda water resisting binder means adhesively uniting the under side of said spring core member to the upper side of said runner lamination, whereby said runner lamination operates through said binder means to prevent deformation of the arch of said spring core member land the binder means prevents moisture reaching the core member through the runner lamination. Y

11. A ski embodying a spring core member having an arch form longitudinally considered, the member; a relatively thin runner lamination havl radius of the are of the under side of the core ing a portion disposed in .an arc concentric to member being longer than the radius of the arc the arc of the under side of the core member; a of the topside of the core member; a relatively relatively thin cover lamination having a porn 5 thin runner lamination having a portion distion disposed in superimposed vposition with re. posed in an arc concentric to the arc of the under spect to the core` member in an arc paralleling side of the core member; and a water resisting the arc of the top side of the core member, a binder means adhesively uniting the under Side waterresisting binder means adhesively uniting of said core member to the upper side of said the under side of said core member to the upper 10 runner lamination, whereby s aid runner laminaside of said runner lamination; and a binder tion operates through said binder means to remeans adhesively uniting the upper side of said sist deformation of the arch of said spring core core member to theunder side of said top lamimember and the binder means prevents moisture nation, whereby said runner and top laminations reaching the core member through the ruimer operate through said-'binder means to resist def- 15 lamination. ormation of the spring arch of said core member 12. A ski embodying a spring core member havand the said water resisting binder means preing an arch form, the radius of the arc'of the vents moisture reaching the core member through under side of the core member being longer than said runner lamination.- the radius of the arc of the top side of the core RAYMOND C. ANDERSON.

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