US2800934A - Bark-removing apparatus having barkimpacting hammers - Google Patents

Description

July 30, 1957 w. A. HOSMER BARK-REMOVING APPARATUS HAVING BARK-IMPACTING HAMMERS 2 Sheets-Sheet l July 30, 1957 w. A. HOSMER BARK-REMOVING APPARATUS HAVING BARK-IMPACTING HAMMERS Filed m 5, 1952 2 Sheets-Sheet 2 BARK-REMOVWG APPARATUS HAVING BARK- IMPACTHNG HAMMERS Windsor Arnold Hosmer, Belmont, Mass.

Application Aagust 5, 1952, Serial No. 392,773

16 Claims. (Cl. 144-208) This invention pertains to apparatus for separating the bark from parts of trees, for example, pulp logs or bolts, as a preliminary step in the preparation of paper pulp or saw-logs preparatory to sawing. It may also be used to remove bark from slabs or edgings produced in a sawmill from unbarked logs. Various mechanical and hydraulic mechanisms have heretofore been proposed and used for removing the bark from logs, but none of these prior devices has proven entirely satisfactory so that hand-peeling of the bark is still used under some circumstances.

The bark of a log is firmly attached to the wood at the cambium layer; the logs to be de-barked are of different diameters and a given log may vary substantially in diameter from end to end; the logs are not mathematically straight or cylindrical and often have knots and other projections, and the bark may vary greatly in thickness on different logs, or even on the same log.

In order that it may be practical and acceptable to the industry, a debarking apparatus should remove a very large percentage of the bark regardless of irregularities in the log, so that hand peeling is reduced to a minimum. On the other hand, such apparatus should be so designed as to avoid substantial chipping of the wood.

The present invention has for its principal object the provision of apparatus for use in separating the bark from the log, and in particular so to separate the bark as to leave the log substantially clean and bare and without chipping into the log, and in such a way that relatively small power is required and by a procedure and means applicable to logs of the usual sizes and having the irregularities customarily encountered in pulp or saw log operations. Specifically, the force for loosening the bark, in accordance with the present invention, is applied as a wedge action, a wedge element, having its apex edge extending lengthwise of the log, being forced through the bark and exerting loosening force simultaneously in opposite directions circumferentially away from a plane which contain the wedge apex and the longitudinal axis of the log, or a line parallel to said axis. By progressing this wedge action from end to end of the log, and by applying such wedge action at a sufficient number of spaced, longitudinally extending planes, the entire sheath of bark is loosened and separated from the wood. A desirable feature in the practice of the invention is the cutting of the bark circumferentially of the log at spaced intervals lengthwise of the log, preferably simultaneously with the application of the wedging force, thereby separating the bark into relatively small pieces which are readily conveyed away from the bark-loosening apparatus.

The present invention is based upon the discovery that if force be applied to the bark in longitudinally extending planes, by wedge-shaped implements which cut or impress longitudinally extending grooves or channels into the bark, thereby creating components of force which act substantially tangent to the surface of the wood in in Q6 ice opposite directions at the cambium layer, such force cracks and loosens the bark from the harder wood at the cambium layer. When force is thus applied by a barkpenetrating wedge, the resistance of the bark (being less than that of the wood) causes the bark to be loosened even at irregular portions of the log, and with only a slight indentation of the wood and without substantial chipping. While good results are obtained by the use of wedges which form longitudinal grooves only, optimum results are secured by forming additional grooves by wedges whose apex edges extend transversely of the log. The bark is thus cut into pieces of short length while at the same time these transversely extending wedges exert a component of force in a direction lengthwise of the log which further assists in cracking the bark from the wood at the cambium layer. Thus the log is left substantially bare of bark, so that little, if any, manual labor is required in cleaning the log for the pulping operation.

Further objects and advantages of the invention will be pointed out in greater detail and by reference to the accompanying drawings wherein:

Fig. 1 is a transverse section through a log, illustrating the principle of loosening the bark in accordance with the present invention;

Fig. la is a fragmentary diagrammatic transverse section, to large scale, illustrating the forces which are believed to be efiective in loosening the bark.

Fig. 2 is a perspective view of a log, illustrative of the type of incisions formed in the bark according to the present invention but without attempt to show the actual number of incisions which is formed;

Fig. 3 is a diagrammatic side elevation of apparatus useful in the practice of the method of the invention;

Fig. 4 is a diagrammatic end elevation showing means for advancing the log for the de-barking operation;

Fig. 5 is an end elevation, diagrammatic in character, illustrating a desirable arrangement of rotors about the circumference of the log;

Fig. 6 is a side elevation, to larger scale, illustrating one of the rotors which carries the Wedge elements for loosening the bark;

Fig. 7 is a fragmentary end elevation of the rotor, partly in section, as indicated by the line 77 in Fig. 6;

Fig. 8 is a fragmentary, perspective view of a combined wedge element and cutter;

Fig. 9 is a section on line 99 of Fig. 7;

Fig. 10 is a diagrammatic elevation illustrative of a desirable way of supporting and driving one of the rotors; and

Fig. 11 is a fragmentary perspective view showing a modification.

Referring to Figs. 1, la and 2, the numeral 1 indicates a bolt of wood or a log such as is used in the pulp or sawmill industry, such log being of any length and diameter customary in those industries. This log comprises the core 2 of solid wood, and the bark 4 which adheres very firmly to the wood at the cambium layer 3. In accordance with the present invention, the bark is loosened from the wood at the cambium layer by forcing a wedge element 5 through the bark so as to form longitudinally extending incisions S. The wedge element herein illustrated has beveled or inclined faces at opposite sides which converge toward the edge, the latter lying in a medium plane of the wedge element, said median plane bisecting the angle between the edge faces so that the wedge action, when the wedge element is forced into the bark, is substantially equal in opposite directions. The inward movement of this wedge element creates force having components in the direction of the arrows F and F tangential to the log and in opposite directions, acting upon the t bark" at the opposite sides of the incision formed by the inward moving" wedge, this" wedge having a cutting or apex edge which is longitudinal of the log. The result ofrthis crowding of the bark in opposite directions is to cause the, bark at opposite sides" of the wedge to crack away from the'wood at a tangential plane with there'- sult that the bark is loosened from the wood. By introducing such wedge elements at intervals sufiiciently close circumferentially of the log, the entire sheet of bark may be loosened at the cambium layer in the form of longitudinally extendingstrips, it being understood that the log and wedge elements will be relatively moved so that the incisions -S, formed by the wedge elements, will extend substantially continuously from end to end of the log. Preferably, to facilitate the removal ofthese loose strips, .circurnferentially extending incision 10 (Fig; 2) will be formed such as to connect the longitudinal incisions S formed by the wedge elements. As a result of this operation, the bark separates from the wood at the c'ambium layer innarrow strips of relatively short length, such as. may readily be conveyed away by appropriate conveyor means, leaving the log substantially bare and requiring butlittle further cleaning to prepare it for the chipping or sawing operation.

The introduction of the wedge elements may be carried out as a hand operation, the wedge elements being forced through the bark, for example, by striking the Wedge elements with a mallet, but for commercial purposes it is desirable to employ power-driven apparatus for forcing the wedge elements through the bark. Figs. 3 to 5 and diagrammatically illustrate appropriate apparatus which is generally indicated by the numeral 11 (Fig. 3). This apparatus comprises. suitable means for advancing the log in an axial direction while the bark is being loosened. As here illustrated, this means comprises a series of rolls 12 on which the log rests, these rolls preferably being in pairs, for instance, as illustrated in Fig. 4, the rolls of each pair being spaced axially and secured to a shaft 13 supported in suitable bearings (not illustrated) in the machine frame. Each of these shafts 13 is provided, for example, with a sprocket wheel 14 which receives a power-driven chain, so as to turn the rolls 12 at the desired speed. These log advancing, rolls may be of any desired construction which is etfectiveto advance the log. Desirably these rolls should have teeth, ribs, spikes or other means for obtaining a very firm grip onthe log, and for this purpose might, for example, consist merely of a series of radiating, sharppointed arms carried by the shaft 13 so devised that the log will rest upon the points of these arms. The particular type of roll forms no essential part of the invention provided, as above described, it grips'the log positively enough to insure theforward propulsion of the log. h

At spaced intervals along the length of'the log pairs of shafts 15, 16, etc. are arranged on which are mounted the carriers for the wedge elements. As suggested in Fig. 5, there are four pairs of these shafts, but the number may be increasedor decreased depending on the range of sizes of logs for which a particular machine is designed. The

axes of all of these shaftsare in planes perpendicular to the longitudinal axis of the log. Preferably the shafts of each respective pair (for example, the shafts 15 and 16) are diametrically opposite, as respects the axis of the log, and, preferably, the axes of the several successive pairs lie in planes parallel to the log axis and defining side faces of'a regular prism. If four pairs are used (Fig. 5) these planes would form an octagonal prism. The shafts of each pair are parallel to a tangent to the circumferential surface of the log, but are at such distances from the axis of the log as to provide for the proper motion of the wedge carrying elements. I

7 To permit the rotor to follow irregularities in the log, the rotor is mounted to permit it to move bodily toward or from'the axis of the log. For example, as illustrated in Fig. 10, the shaft 15 of the rotor R may be mounted in bearings at one end of a tiltable frame T, fulcrumed at having a simple wedgeyele'ment at its end, itis desirable, as I Aso as to swing about an axis in a plane perpendicular to the axis of the log and parallel'to a tangent to the surface of the log. Each rotor may be driven by an independent motor M, shown in Fig. 10 as mounted on the corresponding frame T at the opposite side of the fulcrum from the rotor, and driving the rotor by means of a belt B. However, any other appropriate drive means may be employed.

The parts are so designed that the rotor tends to approach the axis of the log, either by gravity action or by the action of a spring S, or both, so that the rapidly revolving wedge elements engage the bark with the desired bark-cracking force but can retreat from the axis of the log when they encounter abrupt projections such as knots or in response to an increase in the diameter of the log.

Referring to Figs. 6 and 7, each of these shafts, for example the shaft 15, is provided at a point between its ends with a rotor R, shown in Fig. 6, as comprising axially spaced headers H and H Two series of contiguous crank plates 13, 14 are arranged between the headers, the I crank members of one series lying out of phase with those of the otherseries. As here shown (Fig. 7), these crank plates are of elliptical contour though this is not essential. They are fixed to the shaft in any suitable way, as by splining, and have aligned openings for the passage of the crank pins 17, 18, 19 and 20. Successive crank pins are spaced 90 circumferentially of the shaft, and each crank pin carries a series of radial, pivoted arms 21, 22,21 22 etc. free end with a wedge element 23 (Fig. 9) having an apex or cutting edge 24 which extends longitudinally of the log. As here illustrated, each of the arms 21, 22, etc. consists of a length of steel, for example, of the order of inch in thickness and of a width of approximately 1 inch.

A desirable length for the arms 21, 22, etc. is approximate.

ly 4 inches. As shown in Fig. 7, the effective or forward edge of each arm is beveled for a portion of its length, as indicated at 23 (Fig. 7 to provide a wedge-like barkcracking element. An apex angle of approximately 30 is cited by way of example as providing good results. Desirably, the free end portion of each arm is curved, as shown at 25, so that this portion of the. arm, which first contacts the bark, presents a curved apex edge which extends longitudinally of the log.

As illustrated in Fig. 5, there are eight'of the rotors R, the axes of the several rotors being in planes perpendicular to the axis of the log, and also in planes which define the side faces of a regular octagonal prism. Thus the planes of rotation of the arms of the successive rotors, which are parallel to said axis, intersect at at 45.

While desirable results may be obtained if all of the arms carried by each of the shafts is of the above type, each above suggested, to form circumferential incisions 10 at short intervals. For this purpose, certain of the arms 21,,

22, etc. (for instance the arm 21, Fig. 11),. instead of the wedge elements 23, may carry cutter blades, 27*, generally similar to the wedge elements 23, but extending circumferentially of the log so as to form said circumferential incisions 10 (Pig. 2), thereby to cut the bark into I relatively short sections. When the rotor turns inrthe direction of the arrow A in Fig. 11 the cutter blades not only cut the bark into short lengths, but they also exert a wedge action, similar to that of the wedge elements 23, thus assisting in cracking the bark away from the wood. Alternatively, as indicated in Fig. 8, some of the arms, for example the arm 21 may carry composite cutters, including Wedge elements, having the apex edges 24 and also transverse members 26 having cutting edges 27, at right angles to the apex edges 24. These combined cutter devices may be substituted for so many of the simple wedge elements as may be found desirable to divide the Each of these arms is provided at its arrow A (Fig. 7), thereby causing the arms to swing outwardly centrifugally and thus to acquire a substantial momentum such that when they contact the bark, as the log is progressed, the wedge elements will impact the bark with sufilcient force to pass through the thickness of the bark and thus, as above described with respect to Fig. l, to crack the bark at the cambium layer.

The momentum of the swinging arm is such that the wedge passes through the entire thickness of the bark, but, preferably, the wedge should not cut deeply into the solid wood. However, even though the edge does indent the wood, no harm is done except loss of power, since the wood is not chipped nor removed. At the lower part of Fig. 7 the positions of several of the arms 22 are illustrated as their edges contact the bark at various points in its circumference. Since the arms swing freely, the only force available for cutting the bark is that provided by the momentum of the individual arms, and thus the danger of breakage of any of the parts due to variation in diameter of the log or the presence of knots or other projections is minimized. With the arrangement disclosed, the wedge elements contact the bark at suitable intervals throughout its entire circumference so as to split the bark into longi- I tudinal ribbons, each of which is thoroughly loosened from the cambium layer. A rotational speed of the shafts of 1800 R. P. M. has been found desirable in attaining the results, but various speeds may be used, depending upon the character and condition of the logs.

No attempt has been made herein to illustrate in detail the elements of the machine frame, since it is obvious that it is within the skill of the ordinary mechanic to erect a proper frame structure to support the bearings for the various shafts. It is to be understood that while one desirable form of apparatus for wedglng the bark away from the cambium layer has here been illustrated by way of example, the invention is broadly inclusive of any and all means whereby the wedge elements may be eifectively forced through the bark in carrying out the above principles.

From the foregoing it will be evident that the projecting ends of the elliptical plates 13 and 14 provide recesses therebetween for the pivoted ends of the hammers so that the pivot pins for the hammers are supported on each side of each hammer immediately adjacent the hammer. In. the illustration these recesses are disposed in four rows spaced 90 around the periphery of the rotor, the recesses of each row being staggered with respect to the recesses of the next preceding and succeeding rows. Thus the recesses are disposed between planes perpendicular to the axis of the rotor with at least one recess between each pair of adjacent planes, the width of the recesses being substantially equal to the distance between planes and the width of the hammers being substantially equal to that of the recesses, so that the hammers strike the pieces throughout substantially the entire length of the rotor and the pivoted end of each hammer may be as wide as its projecting portion.

I claim:

1. Apparatus for use in debarking a slab or a log, said apparatus comprising means for axially and nonrotatably feeding a slab or a log, a plurality of wedge elements each having an apex edge lying in a median plane of the wedge element which is substantially parallel to the axis of a slab or a log being debarked, and means operative to force each of said wedge elements into the bark as a slab or a log advances axially relatively to said wedge elements whereby the bark is crowded apart in opposite directions tangentially of such a slab or log by each wedge element, the se eral wedge elements being transversely spaced so that in approaching the bark their apex edges strike the bark glancing blows directed lengthwise of such a slab or log at circumferentially spaced points.

2. Apparatus for use in debarking a log, said apparatus comprising means for positioning a log, a plurality of groups of wedge elements, each wedge element having an elongate apex edge which moves in a plane substantially parallel to the longitudinal axis of a log being debarked, the wedge elements of each respective group having relative movement in parallel paths, the planes of movement of the elements of one group intersecting the planes of movement of the elements of the next adjacent group, the planes of movement of certain elements of each group containing or extending close to said longitudinal axis, and means for impacting each wedge element against the bark with force sutlicient to crack the bark and to crowd the bark in opposite directions circumferentially of such a log.

3. Apparatus for use in debarking a log, said apparatus comprising means for positioning a log, a plurality of groups of wedge elements, each wedge element having an elongate apex edge which moves in a plane substantially parallel to the longitudinal axis of a log being debarked, the wedge elements of each respective group having relative movement in parallel paths, the planes of movement of the elements of one group intersecting the planes of movement of the elements of the next adjacent group at an angle of approximately 45, and means for causing each wedge element to impact the bark with force sufiicient to crack the bark longitudinally.

4. Apparatus for use in debarking a log, said apparatus comprising means for positioning a log, a plurality of groups of wedge elements, each Wedge element having an elongate apex edge which moves in a plane substantially parallel to the longitudinal axis of a log being debarked, the wedge elements of each respective group having relative movement in parallel paths, the planes of movement of the elements of one group intersecting the planes of movement of the elements of the next adjacent group at an angle of approximately 45, the elements of those groups which are disposed at diametrically opposite sides of a log having the same planes of movement, each pair of oppositely disposed groups of elements being spaced lengthwise of such a log from an adjacent pair, and means for causing each wedge element to impact the bark of the log with a force sutficient to crack the bark longitudinally.

5. Apparatus for use in debarking a slab or log, said apparatus comprising means for positioning such a slab or log, a rotor turning about an axis which lies in a plane perpendicular to the longitudinal axis of a slab or log and said rotor axis extending parallel to a tangent to such slab or log, an arm carried by the rotor, a wedge element carried by the arm, the wedge element having an apex edge lying in a median plane of the wedge element which is substantially parallel to said longitudinal axis, and means for turning the rotor, the length of the arm being such that as the rotor turns the wedge element impacts the bark by a glancing blow directed lengthwise of such a log.

6. Apparatus for use in debarking a slab or log, said apparatus comprising means for positioning such a slab or log, a rotor turning about an axis which lies in a plane perpendicular to the longitudinal axis of a slab or log being debarked and which lies parallel to a tangent to such a slab or log, an arm pivotally connected at one end to the rotor, a wedge element carried by the arm, the wedge element having an apex edge which moves in a plane substantially parallel to said longitudinal axis, means for turning the rotor, thereby to impact the wedge element against the bark, and means supporting the rotor for bodily movement toward and from said tangent.

7. In apparatus for debarking slabs or logs, in combination, means for moving a slab or log in its axial direction, a rotary shaft whose axis of rotation lies in a plane perpendicular to said axial direction and lies parallel to but spaced from a tangent to such a slab or log being debarked, a rotor mounted on the shaft, arms pivoted to the rotor at diametrically opposite sides of the shaft and at points spaced from the axis of the shaft, 2.

wedge. element: at the free end of each'arm which moves, in aplanar path. substantially parallel to said axial direction, saidzwedge element having an apex edge lying in a median plane of the wedge element which bisects the angle between two convergent faces, and the arms being of such length that as the shaft turns and such a slab or log advances, the wedge elements impact the bark on the slab or log by glancing blows directed lengthwise of such slab or log.

1 8. 'In'apparatus' for debarking slabs or logs, in combination, means for moving a slab or a log in its axial direction, a rotary shaft whose. axis of rotation lies in a plane perpendicular to said axial direction and lies parallel to but spaced from a tangent to such a slab or log being debarked, a rotor mounted on the shaft, the rotor comprising elongate crank pins parallel to the axis of the shaft and at diametrically opposite sides of the latter, a plurality of arms pivotally connected to each crank pin, a Wedge element at the free end of each arm, each wedge element having an apex edge which moves in a plane substantially parallel to said axial direction, an arm on one of said crank pins containing a plane of movement intervening between the planes of movement of adjacent arms on the opposite pin, and means for rotating the shaft.

9. In apparatus for debarking slabs or logs, in combination, means for moving a slab or log in its axial direction, a rotary shaft whose axis of rotation lies in a plane perpendicular to said axial direction and lies parallel to but spaced from a tangent to such a slab or log being debarked, a rotor mounted on the shaft, the rotor having,

elongate crank pins arranged 90 apart about the axis of the shaft, each crank pin being parallel tothe axis of the shaft, a plurality of arms each pivoted at one end on its respective crank pin, certain of said arms each having a wedge element at its free end, each wedge element having an apex edge movable in a plane parallel to said axial direction, each of certain other arms having a cutter provided with a cutting edge extending transversely to said axial direction, the arms being of such length that as the shaft rotates the wedge elements and cutters impact the bark, and means for rotating the shaft.

10. In apparatus for debarking logs, in combination, means for advancing a log in its axial direction, rotary shafts whose axes of rotation are in planes perpendicular to and which are spaced longitudinally ofsaid axial direction, each shaft being parallel to but spaced from a tangent to a log being debarked, the axes of the several shafts lying in planes which constituteside faces of a regular prism coaxial with such a log, each shaft carrying a crank pin, an arm pivoted to each crank pin,- certain of said arms carrying wedge elements each having an apex edge which moves in a plane parallel to said axial 7 direction, and means for rotating the shaft, thereby to impact the wedge elements against the bark,

11. In apparatus for debarking logs, in combination, means for advancing a log in its axial direction, rotary shafts whose axes of rotation are in planes perpendicular to and which are spaced longitudinally of said axial direction, each shaft being parallel to but'spaced froma tangent to a log being debarked, the axes of the several shafts lying in planes which constituteside faces of a regular prism coaxial with such a log, each shaft carrying a crank pin, an arm pivoted to each crank pin, certain of said arms carrying wedge elements having apex edges disposed parallel to the axes of the shafts which carry the respective crank pins and other of said arms carrying wedge elements having apex edges movable in planes parallel to said axial direction, and means for rotating the shaft. 1

12.'In apparatus for debarking logs in combination, means for advancing a log in its axial direction, rotary shafts whose axes of rotation are in planes perpendicular to and spaced longitudinally of said axial direction, each shaft being parallel to but spaced from a tangent to such a log being debarked, the axes of the several shafts lying in p ane hich qo t es d f ce o e u rp i m ax al h. u h a oa ac h ft y n a cra k; pin

an arm pivoted to each crank pin, certain of said arrns carrying combined wedge elements and cutters opezrative.

simultaneouslyto form lengthwise and circumferential incisions in the bark, and means for rotating the several shafts simultaneously.

13; Apparatus for use in debarking a piece: of wood whose bark-covered surface is curved transversely and extends relatively straight longitudinally, said apparatus comprising means for positioning such a piece, a rotor turning about an axis which lies in a plane perpendicular to the-lengthwise axis of a piece being debarked and is parallel to a tangent to said curved bark-covered surface, an arm pivotally connected at one end to the rotor, at the free end of each arm a wedge element having an apex edge which moves in a plane substantially parallel to the lengthwise axis of such a piece, means for turning the rotor to impact the wedge element against the bark,

and means supporting the rotor for bodily movement toward and from said tangent.

14. In apparatus for debarking a piece of wood whose bark-covered surface is curved transversely and extends relatively straight longitudinally, in combination, means for moving such a piece in its lengthwise direction, a rotary shaft whose axis of rotation lies in a plane perpendicular to said lengthwise direction and lies parallel to but spaced from a tangent to said curved bark-covered surface, a rotor mounted on the shaft, the rotor comprising elongate crank pins parallel to the axis of the shaft and at diametrically opposite sides of the latter, a plurality of arms pivotally connected to each crank pin, a wedge element at the free end ofeach arm, each wedge element having an apex edge which moves in a plane substantially parallel to said lengthwise direction, an arm on one of said crank pins containing a plane of movementintervening between the planes of movement of adjacent arms on the opposite pin, and means for rotating the shaft.

15. For debarking a piece of wood, a machine comprising a carrier for transporting a piece of wood along a predetermined path, a rotor having its axis of rotation extending transversely of the path at one side thereof, and hammers pivotally mounted on the periphery of the rotor to swing a planar paths perpendicular to said axis and to project radially therefrom in response to centrifugal force, the distance between said predetermined path and axis being such that the hammers strike such piece of wood glancing blows as it is transported past the rotor by the carrier, the rotor comprising a series of plates disposed transversely of the axis, each plate being elongate transversely of the rotor axis and having an opening near eachend, the longer dimensions of alternate plates being at right angles to each other, shafts extendingthrough the openings at corresponding ends of the several plates, the

hammers being pivotally mounted on said shafts and located in'the spaces between alternate plates, each hammer having a curved impact element at the leading side of its outer end.

16. Apparatus for debarking pieces of wood comprise 7 port pieces of wood past the rotor along a path close enough to the rotor so that substantially all the hammers can reach a piece irrespective of the contour thereof, said recesses being disposed between planes perpendicular to the axis of the rotor with at least one recess between each pair of adjacent planes, the width of the recesses being substantially equal to the distance between planes and the width of the hammers being substantially equal to that of the recesses, so that the hammers strike the pieces throughout substantially the enire lengh of the rotor and the pivoted end of each hammer may be as wide as its projecting portion.

References Cited in the file of this patent UNITED STATES PATENTS Hansson Dec. 9, 1902 De Cew July 17, 1917 Cote Aug. 18, 1925 Noyes Sept. 8, 1925 Hummel May 22, 1928 Pangborn June 12, 1928 Genes et a1. Oct. 11, 1932 10 Council Mar. 13, 1934 Kenney Apr. 2, 1946 Daniell Feb. 24, 1948 Williford June 10, 1952 Eklund et a1 Aug. 26, 1952 Kolpe et a1 July 21, 1953 Denison Sept. 29, 1953 FOREIGN PATENTS Sweden Dec. 5, 1896 Sweden Oct. 16, 1918 France Jan. 7, 1944 Great Britain Oct. 31, 1951

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