US3172429A - Fortified picker sticks - Google Patents

Description

March 9, 1965 w. R. EGBERT FORTIFIED PICKER STICKS Filed Oct. 29, 1963 mum IN V EN TOR.

WILLIAM R. EGBERT L: QL a BY PM, gram, M

ATTORNEYS.

United States Patent 3,172,429 FORTIFIED PICKER STICKS William R. Egbert, Mohawk, N.Y., assignor to Lundstrom Laboratories, Inc, Herlrimer, N.Y., a corporation of New York Filed Oct. 29, 1963, Ser. No. 320,257 3 Claims. (Cl. 139-157) This application is a continuation-in-part of my copending application, Serial No. 832,026, filed August 6, 1959, now abandoned.

This invention relates to new and useful improvements in picker sticks.

In the operation of looms, a shuttle carrying the weft thread is shot back and forth across the warp shed by pickers fitted on the free ends of sticks mounted for fast rocking movement at opposite sides of the shed. When the shuttle arrives at one side of the loom, the picker stick at that side is rocked on a pivot at its butt end with a fast whipping motion which throws the shuttle at high speed back across the loom to the picker at the other side of the loom.

In order to achieve a required combination of whip and endurance, picker sticks are usually machined from blanks of a resilient natural wood such as hickory. Some picker sticks have been made of layers of plywood impregnated and bound together under heat and pressure by a thermosetting synthetic resin, in order to obtain better strength and wearing qualities in the sticks; but such sticks as heretofore made have been relatively expensive, and they do not possess the resilience or whip on looms which is provided by natural hickory picker sticks and is important to the successful operation of looms at very high picker speeds.

It has been proposed to improve the wear resistance of picker sticks while preserving the required resilience and shock resistance, by forming wooden blanks with oversized portions or bosses on their edges rat the principal zones of wear and, through a process of wood densification, compressing the bosses into the main body of the wood so as to densify and harden each stick locally where it otherwise would soon wear away. Experience has shown, however, that picker sticks made in that way suffer localized overstressings of the wood fibers, which affect the strength of the wood and often lead to warping of the sticks and to splintering or breaking of the sticks in loom service.

It is a principal object of this invention to provide new and improved wooden picker sticks which will perform reliably and withstand the wear and shocks imposed upon them in loom service for much longer periods than usual wooden picker sticks.

Another object is to provide wooden picker sticks which are considerably enhanced in strength as well as in wear resistance and which still possess the properties of whip or resilience required for good performance on a loom.

A further object of the invention is to provide a manner of production of picker sticks by which in a single forming operation wooden blanks not only are increased in strength and wear resistance and kept resilient but also are brought to the final thickness desired in the finished sticks, thus enabling the elimination of a difficult and expensive machining operation heretofore required for the finishing of picker sticks.

Still another object is to provide wooden picker sticks which do not warp on long exposure to atmospheric moisture.

According to the present invention, I have provided a picker stick construction wherein an elongated unitary body of wood composed essentially of the integrated fibers and lignin of a piece or blank of natural hardwood formed into the picker stick is compressed and densified from "ice opposite sides thereof over most, or more advantageously all, of its length so as to be composed throughout the picker end portion thereof, and also in and evenly along outer zones of the long body portion extending from the picker end portion to the butt end of the stick, of densified yet still integrated natural fibers and lignin having a density and hardness substantially greater than that of the natural hardwood, and yet wherein the densification is so limited that the body continues to have a relatively undensified core or central zonelying between and extending throughout the length of the densified outer zones, in which the density and hardness of the wood at any location therealong is less and the resilience thereof is greater than that of the contiguous wood in said outer zones and than that of the wood of the picker end portion.

Further, the densified outer zones of the hardwood body are formed with sealed toughened facial layers constituted by a hardening and sealing agent, such, for example, as a suitable resin-forming composition, having been applied to the opposite sides of the body prior to their being compressed and densified. These layers stabilize the densified outer zones, making the picker stick highly resistant to warping and other changes of its properties.

I have found that picker sticks made to embody such a construction have an extraordinarily valuable combination of properties. Not only their wear resistance but also their strength, their stability and their service life are greatly enhanced, and yet they also exhibit qualities of resilience and whip, together with a limited weight, which suit them excellently for the exacting performance requirements of modern high speed loom operations.

The picker end portion of each stick is advantageously compressed and densified throughout its thickness to an approximately uniform density and hardness at least as great as that produced in any of the other densified zones of the stick body. The wood of the other body portions may be compressed and densified along opposite sides thereof to possess hardness progressively increasing therealong from the butt end portion to the picker end portion of the stick, yet in a central zone or core along the body this wood is kept less densified and hence more resilient or flexible than the contiguous wood near the surfaces of the compressed sides.

The production of picker sticks embodying the construction of this invention is readily carried out by subjecting oversized wooden blanks after a suitable pretreatment of each blank to a tapering compression between heated platens which deform the blanks into densified bodies tapering in thickness from end to end thereof, with the least thickness at the picker end, and limiting the compression so that when the picker end portion and outer zones of the other body portions of each blank have attained the desired degrees of increased density and hardness there will still be a core or central zone of more resilient wood extending throughout thethe densified body. By the single compression operationthe opposite sides or faces of each of the blanks can be brought to the form and also tothe surface finish desired in the finished picker sticks, so that no machining operation will be required on either of these faces in order to complete the final shaping and finishing of the sticks.

The blanks used are preferably made of natural wood that is highly resilient, such as well cured hickory wood or other suitable natural hardwood.

Other objects, features and advantages of the invention and preferred ways of practicing it will be apparent from the following detailed description of an illustrative embodiment. The detailed description refers to the accompanying drawing in which:

FIG. 1 is a perspective view, partially broken away, of a finished picker stick constructed according to the invention;

FIG. 2 is a similar perspective view of a compressed picker stick blank before conversion into the finished stick, the stipling on this figure indicating different conditions of density and hardness of the wood;

FIG. 3 is a schematic view in side elevation of a raw wooden blank positioned alongside a die between press platens in readiness for compression of the blank; and

FIG. 4 is a View similar to FIG. 3 showing the relationship of the blank, the die and the platens at the end of the compression operation.

In FIG. 1 of the drawing there is shown a finished wooden picker stick made according to this invention which corresponds in its major dimensions to the picker sticks widely used on certain commercial looms. The stick shown is formed with its body compressed and tapered evenly in thickness between its opposite sides or faces 11 and 12, over its entire length from the base 14 of its butt end portion 15 to a point of least thickness at the tip'19 of its picker end portion 18. The greatest extent of compression, density and hardness is provided in the wood of the picker end portion 18. The Wood of the butt end portion 15 and intermediate portion 16 of the stick body, i.e., of the long body portion extending away from the picker end portion, is'compressed and densified along opposite sides thereof to a limited extent so as to possess in outer zones thereof along these sides an increased density and hardness which at any location therealong is substantially greater than the density and hardness of the wood in a core or central zone of the body lying between the densified outer zones.

The finished stick 10 of FIG. 1 is machined from a compressed blank such asshown at 10A in FIG. 2. The compressed blank in turn is formed from a raw blank such as seen at 10B in FIG. 3 of the drawing. The varied conditions of compression, density and hardness provided along the body of the stick are represented diagrammatically by the stipling applied in FIG. 2 to the front edge of the compressed blank 10A.

In the illustrative stick 10 and blank 10A here shown, the wood of the picker end portion 18 is compressed and densified throughout its thickness to a hardness substantially greater than that of the natural hardwood blank formed into the stick body. The wood in outer zones of the body near the side surfaces of intermediate portion 16 is compressed and densified to a hardness less than that of portion 18 but greater than that of the wood of the butt end portion 15. The wood of the butt end portion is somewhat compressed and densified near its sidesurfaces but is kept substantially entirely uncompressed in a central zone 17 between its opposite sides, At any point along the stick body from the butt end portion 15 through the intermediate portion 16, the density and hardness of the wood near the surfaces of the compressed sides is greater than that of the wood in the central zone of the body between those sides.

The varied conditions of compression, density and hardness provided in the several portions of the illustrative picker stick may be further indicated by reference to illustrative hardness measurements made at typical points in outer zones and in the central zone of each of the body portions 15, 16 and 18. See FIG. 2. At a central point 150 of the butt end portion 15, the wood has substantially the same density and hardness as the original wood used to make the raw blank 10B. In the use of natural hickory wood, the hardness at point 15c amounts, for example, to approximately 75 Shore Durometer units, plus or minus 5 units, as determined by tests with a Shore Durometer, Type D, produced by the Shore Instrument Manufacturing Company of the wood has a somewhat greater density manifested by a hardness reading, for example, of approximately Shore units. In the intermediate portion 16 of the body, the wood in the outer zones asat points 16a and 16b is quite materially increased in density to a hardness reading, for example, of approximately 86 Shore units; while in the central zone at point 160 the hardness is less than at the outer points but stillis. greater than in the central zone of the butt end portion, being, for example, approximately 84 Shore units. In the picker end portion 18, which is compressed and densified to an approximately uniform hardness throughout it's thickness, the hardness reading amounts, for example, to approximately 90 Shore units at each of the points 18a, 18b and 180.

An eifective manner of forming a wooden blank into the compressed blank of FIG. 2 is illustrated schemat ically in FIGS. 3 and 4 of the drawing. The raw blank 19B is cut from the desired hardwood, such as hickory, to approximately the same length and width as required for the compressed blank NA, and to a thickness greater than required for the compressed blank. Its thickness in the form shown is approximately uniform from end to end of the wooden body.

The blank IQB when ready to be compressed is placed in a press between heated platens 30 and 32 which are capable of applying to the blank a high pressure of the order, for example, of 1500 pounds'per square inch. The blank is laid on the lower-:platen 32 alongside an incompressible die 34 serving as a stop to limit the convergence of the two platens. There are similar dies or steps at either side of the blank, each taperedto correspond to the dimensions and taper desired in the thickness of the finished picker stick.

Before being placed in the press, the blank 19B is suitably heated in order to pre-plasticize lignin contained in the wood, such as by treating it with live steam or hot air. This treatment advantageously is preceded, accompanied .or followed by the application of a resinforming solution to at least the opposite side faces of the blank, such as a solution which at the elevated temperature of the press platens will form in pores of the wood a 'thermostat'resin such as. a urea-formaldehyde resin, a

melamine resin, or the like. Thus under the heat and pressure of the press'platens a desirable dense, smooth and tough impregnated surface, which seals the pores of the wood against moisture absorption and inhibits the natural tendency of picker-sticks to warp, is formed on the compressed sides of the blank. Fo the latter purpose, the blank may be coated on both of its faces with an aqueous solution of the character described in US. Patent No. 2,567,292 to 'Carl Brynolf Lundstrom.

Having been suitably pre-treated and placed in the press as indicated in FIG. 3, the blank 10B is subjected to compression between the platens 30 and 32, while being heated by the platens, until the platens have closed against the die 34 as'seen in FIG. 4. As the'compression of theblankproceeds, the platens become tilted, one relative to the other, by their coaction against the faces of the blank and the die. In a typical operation, for example, the platens are heated to a temperature of approximately 300 F. and are pressed together against the blank and die under a pressure of approximately 1500 pounds'per square inch for a period of approximately 40 minutes. After the platens have closed against the die, they. are held closed under pressure and cooled to a temperature of F. or below to set the displaced lignin and fibers in the compressed blank so that the product will remain permanently in the densified and hardened form shown in stick the desired final width and the desired tapered edge 21a along the picker end portion; drilling an opening 24 through the butt end to be fitted with a bushing and a loom mounting pivot; and drilling openings 25 and 26 through the central zone of the butt end at either side of the pivot opening to receive butt reinforcing bolts.

A typical finished picker stick made according to this invention has, for example, a length of 34 /2 inches, a width of 1% inches which at the picker end portion is tapered down to a tip Width of 1 inch, and a thickness tapering evenly from /8 inch at the base of the butt end to /8 inch at the tip of the picker end. The uncompressed blank used for the production of such a stick has, for example, a length of 35 inches, a width of 2 inches and a thickness of inoh. After the compression operation, the length and the width of the blank remain approximately the same but its thickness is reduced to the final values present in the finished stick, i.e. its thickness tapers evenly from inch at the base of the butt end to inch at the tip of the picker end.

It will be understood, of course, that the dimensions, the values of hardness measurements and other details of the illustrative embodiment as set folth herein are subject to wide variations, depending upon the desired size and other desired qualities of the finished picker sticks. For example, when it is desired that the stick have a greater mass in the butt end and intermediate portions, the uncompressed blank is cut on a taper so as to have a greater thickness at the base of the butt end and to decrease in thickness evenly to its other end; in which case the upper platen 30 of the press assumes a tilted position relative to the lower platen at the outset of the compression and the compressed outer zones of the densified blank are more nearly uniform in density and hardness over their length.

The invention is not intended to be restricted to particulars or details of the illustrative embodiments herein described except as may be required by a fair construction of the appended claims.

I claim:

1. A picker stick comprising an elongated unitary wooden body composed essentially of integrated fibers and lignin of a piece of natural hardwood and defining at one end a butt end portion adapted to be pivoted on a loom, at the other end a picker end portion adapted to hold a loom picker, and between said end portions a relatively long intermediate portion, said fibers and lignin of opposite sides of said body being compressed and densified, by having been plastically displaced under heat and pressure and reset by cooling under continued pressure, in outer zones of said body extending the full breadth and length of the opposite sides of said body, and possessing at any location in said outer zones a density and hardness substantially greater than that of the natural hardwood, said outer zones comprising sealed toughened facial layers constituted by a hardening and sealing agent having been applied to said opposite sides prior to their being compressed and densified, to inhibit warping of said body, there being a relatively undensified core of the body composed only of integrated hardwood fibers and lignin and lying between said outer zones from the end of said butt end portion at least to said picker end portion, the density and hardness of the wood in said core at any location therealong being less than that of the contiguous wood in said outer zones, whereby the stick possesses extraordinary durability together with the Whip required for high speed looms.

2. A picker stick comprising an elongated unitary body of hickory wood having at one end a butt end portion adapted to be pivoted on a loom and having at its other end a portion adapted to hold a loom picker, said body tapering in thickness from end to end thereof to a point of least thickness at its picker end, and being composed essentially in outer zones of the body extending the full length and breadth of its opposite sides of integrated hickory fibers and lignin plastically displaced under heat and pressure and reset under continued pressure in compressed and densified condition, and having throughout said outer zones a hardness substantially greater than that of the natural hickory wood, said outer zones comprising sealed toughened facial layers constituted by a thermosetting resin impregnated and set in pores of the wood from said opposite sides to inhibit warping of said body, said body having between said outer zones from the end of said butt end portion at least to said picker end portion a central Zone composed only of integrated hickory fibers and lignin and in which, at any point therealong, the hardness of the wood is less and its resilience greater than in the contiguous wood of said outer zones, whereby the stick possesses extraordinary durability together with the Whip required for high speed looms.

3. A picker stick as set forth in claim 2, wherein the hardness of the wood in said outer zones increases progressively therealong from said butt end portion to said picker end portion.

References Cited by the Examiner UNITED STATES PATENTS 2,101,542 12/37 Hartzell l44327 2,470,506 5/49 Lundstrom 1 391 5 7 2,586,308 2/52 Curtis 144327 2,606,576 8/52 Cox 139157 FOREIGN PATENTS 991,362 6/51 France. 286,059 5/31 Italy.

DONALD W. PARKER, Primary Examiner.

MERVIN STEIN, Examiner.

Claims (1)

1. A PICKER STICK COMPRISING AN ELONGATED UNITARY WOODEN BODY COMPOSED ESSENTIALLY OF INTEGRATED FIBERS AND LIGNIN OF A PIECE OF NATURAL HARDWOOD AND DEFINING AT ONE END A BUTT END PORTION ADAPTED TO BE PIVOTED ON A LOOM, AT THE OTHER END A PICKER END PORTION ADAPTED TO HOLD A LOOM PICKER, AND BETWEEN SAID END PORTIONS A RELATIVELY LONG INTERMEDIATE PORTION, SAID FIBERS AND LIGNIN OF OPPOSITE SIDES OF SAID BODY BEING COMPRESSES AND DENSIFIED, BY HAVING BEEN PLASTICALLY DISPLACED UNDER HEAT AND PRESSURE AND REST BY COOLING UNDER CONTINUED PRESSURE, IN OUTER ZONES OF SAID BODY EXTENDING THE FULL BREADTH AND LENGTH OF THE OPPOSITE SIDES OF SAID BODY, AND POSSESSING AT ANY LOCATION IN SAID OUTER ZONES A DENSITY AND HARDNESS SUBSTANTIALLY GREATER THAN THAT OF THE NATURAL HARDWOOD, SAID OUTER ZONES COMPRISING SEALED TOUGHENED FACIAL LAYERS CONSTITUTED BY A HARDENING AND SEALING AGENT HAVING BEEN APPLIED TO SAID OPPOSITE SIDES PRIOR TO THEIR BEING COMPRESSED AND DENSIFIED, TO INHIBIT WARPING OF SAID BODY, THERE BEING A RELATIVELY UNDENSIFIED CORE OF THE BODY COMPOSED ONLY OF INTEGRATED HARDWOOD FIBERS AND LIGNIN AND LYING BETWEEN SAID OUTER ZONES FROM THE END OF SAID BUTT END PORTION AT LEAST TO SAID PICKER END PORTION, THE DENSITY AND HARDNESS OF THE WOOD IN SAID CORE AT ANY LOCATION THEREALONG BEING LESS THAN THAT OF THE CONTIGUOUS WOOD IN SAID OUTER ZONES, WHEREBY THE STICK POSSESSES EXTRAORDINARY DURABILITY TOGETHER WITH THE WHIP REQUIRED FOR HIGH SPEED LOOMS.

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