US2476361A - Universally adjustable work holding means - Google Patents

Description

July 19, 1949. A. K. ELLIOTT ETAL UNIVERSALLY ADJUSTABLE WORK HOLDING MEANS 3 Sheets-Sheet 1 Filed April 2, 1946 J y 1949- A. K. ELLIOTT ETAL UNIVERSALLY ADJUSTABLE WORK HOLDING MEANS 5 a, 2 W 7 U M. 7 7 m a M M w m e g 7 up I t K m 5 w 5 M S & Md 5 l v 4 4 fir u M Z a w w /v Filed April 2, 1946 y 1949- A. K. ELLIOTT ETAL 2,476,361

UNIVERSALLY ADJUSTABLE WORK HOLDING MEANS Filed April 2, 1946 s Shets-Sheet s Patented July 19, 1949 Amfis r ipiii 'Wofiii HOLDING MEANS Alan-26 K: iinim tin-e Theodore fr. Indianapolis"; Ind;

A plication Aiifii' 2", 1946 Serial its. esast' 12' claims. (01. 5:234)

of such wheeler cutter to the predetermined complementary shape or outline incident to the repeated use of such dressingwheel, I

The use of the present attachment in-a tool department eliminates the necessity ofhaving individual, complementary formed grinding wheelsor cutters for each shaped tool or work desired. The attachment permits the use of a conventional grinding disc ofv carborundum; diamond or like type, thetype of wheel or cutter be ing determined by the type of material of which the tool or work is made.

The only dressing required with this attachment is the conventional dressing to form or maintain a truly cylindrical surfaceoir the wheel or cutter.

It will be appreciated that this is relatively simple to effect and maintain, notwithstanding gradual reduction indiameter of such wheel or cutter incident to its repeated use; In other words, one grindingwheel: or cuttercan be used until the wheel or cutter is exhausted; and usually for any and all shapes desired.

The chief objective of this invention is to'provide an attachment which is adapted to' mountthe work (usually a forming tool) and initially set that work for apredetermined working clearance, then adjust'the' attachmentupofitwo axes transverse to each other and to'tlie axis" of working clearance adjustment; the latter" being between 5 to '7- and usually being abo'ut Giulthough not necessarily'restricted thereto.

The attachment includes a main akis' slipptirt and the element'-swivelled thereon is tubular and p is adapted to receive a' setting bar which" carries a micrometer frame, in turn mourning af'ni'ic'roina eter. This unit is utilized to positioi lf w rk with respect to two axes sd'that a sfthe rli is oscillated r'elative'to'th Iiiiic ifaxis com f'u'iili curves are formed by the'gri'ridiri'g'wheldruttf,

2 which curves are tomat' lly breadedmtd time adja'efit forr'riid "'urfa of the tool. k

The: aetiiai time for he production ore m: pound agi igle 6661s y t s invefi on is a fp o a mately 20% to 25% or t atu l timeredu ed nretofcire iii the conventional profd methods for these teeisami as will hereina be pointed out, every tool will be of pre'ci on ac} curacy. In other wbf'ds" the element of w of the: leihen't has nb effect on the forma tionof the tool, s'o 'tliat all tools win be exactly alike. c iif i featur at this mvennon resides the efci' reme sirriplity' of construction of the a ta hme t th elefiiie i few pa t id e accuracy of the adjustments provided etween the parts, where bycompound ngling ieaut a nef e ieq.efiEt the i s a justed for the production ofa tool requiring edifipoundanglingto b incorporated therein. ,7

other tu e of th in e i p e i 'i'r to certain attachments illus trated hereiri and hereinafter described by way of exainp le oriiy, which attachments can be associated with the device heretoforedescribed V Other objects d..$?P lr,. ,1? invefifiofi wiltbe t1 .m tel fiere ee ere c The f l et epf theier efieeri fi iie 'ers o d f o illeee empar ie si f and We following description and claims-: i J v v n marines Ri -.4 sere' r ei I i' the device embedyi e. heieyee i e ar d 'vi 'fi Q 9 micrometer settingmechanism associated there- Fig-.-1 is;verynear1y a sideelevation N M Fig. 2 isa perspectiye view oj the invention with a pi o W r .InQll li d;th re nhihemir crometer me n mi eea ine iees qnd P se:- tion; and the View is taken looking toward the tool holding end and-what might be termed the front of the device. p

Fig: 3- a longitudinal sectional view of the work holder and" its" supplementary holding elemeats-- illustrated more fully in Figs; I aInd-Z and with" the s ettifig' be? mieronieter device removed.

3 2 with an adaptor mounted therein and a drill mounted in the adapter.

Fig. 8 is a top plan view of the adapter and drill only.

Fig. 9 is a perspective (nearly a side elevational) view of another embodiment of the invention.

Fig. 10 is a central sectional View of the work holder portion shown in Fig. 9 and is taken on line |H--l of Fig. 9 and in the direction of the arrows.

In Figs. 1 and 2, l0 indicates a base plate, H a back plate portion, and I2 a portion immediately forward the latter, the back plate and portion I2 terminating in what might be termed a bearing or tail stock arrangement, which rotatably supports a tubular spindle [3, the latter at its forward end including a circular portion l4 and from which projects diagonally the portion l5. This spindle and diagonally projecting portion is coaxially bored as at l6 for the accommodation of a so-called setting bar I! to which reference will be had more fully hereinafter.

The forward end of the portion l includes a portion 18 which extends parallel to the spindle portion and forwardl thereof but in offset relation thereto. This forward portion is faced as at H! and a part of the forward portion is arcuately recessed as at 20 to rotatably support an arcuate rearward projection 2| of the member 22.

The member 2| is centrally apertured as at 23 and it is enlarged as at 24 to take the head .25 of a bolt member 26, and the latter extends through the coaxial aperture 21 in the portion [8. A nut 28 engages the threaded end of the bolt 26 to clamp the members l8 and 22 together in the adjusted position.

A pin '29 extends through the head of the clamping bolt and into the pin seating hole 30 opening into the enlargement 24, as shown in Fig. 3. The purpose of the enlargement 24 is to nest, as it were, the head 25 of the .bolt for clearance purposes.

Referring to Fig. 2 it will be noted that the portion l4 includes a degree scale 3| and associated therewith on the portion I2 is the zero and vernier reading arrangement 30.

The portion IS, on its base closest to the spindle bore, includes a similar zero and Vernier arrangement 33 and the arcuate portion 21 includes the degree scale 34.

Projecting forwardly from the portion 22 is a tongue 35 and the same terminates in a cylindrical formation which is coaxially apertured as at 36. A work holder or clamp has a base 31 from which extends rearwardly a pair of spaced ears 38 which straddle the circular tongue 35, and they are coaxially apertured, and a bolt having head 39, shank portion 40, and mounting the washer 4] and a nut 42 serve to retain the work holding piece and the member 22 in the adjusted angular position.

It is to be understood that the axis of this clamping bolt is transverse to the axis of the clamping bolt 26. A similar scale and zero and Vernier arrangement may be provided between portion 35 and the work holding piece.

The work holding piece may take any suitable form, but preferably the same includes a forwardly projecting keystone portion 43, and slidable thereon is a channel-shaped holder 44 having the forwardly projecting parallel plate portions 45, and the base 44 includes a dove-tail slot 46 that is slidably associated with the keystone way 43. This constitutes a gib construction,

Herein portion 44 is longitudinally slotted as at 41, and a plurality of tapped holes 48 transverse thereto accommodate Allen screws 49 or the like, and by this means, the U-shaped member aforesaid, including sides and base 44, can be clamped rigidly to the member 31 having the cars 38.

The means for adjusting the two parts includes the usual threaded arrangement 50 and threaded stem 5| and having the square and exposed end 52.

Rotation in one direction or the other of the threaded member 5| will cause the U-shaped holder to be moved to the right or left, in Fig. 2, of the same relative to the piece 31. When proper adjustment has been made the U-shaped holder is rigidly associated with the piece 31 in the adjusted position.

The U-shaped holder is adapted to accommodate the work W and as many spacing blocks S as may be desired or required, and the clamp screws 53 rigidly clamp the work in the holder. Both sides 45 of the work holder may be aper tured as at 54 to take clamping members 53,

As shown in Figs. 1 and 2, a U-shaped crank 55 may be provided and associated with each of 50 spindle portion l3.

the squared ends 56, see Fig. 4, of the shaft 5'5 rotatably supported in the bearings 58 in the bore 59 transverse to the spindle receiving bore l6 in the portion l3 and communicating therewith. Shaft 51 has intermediate its ends the worm 63, the same meshing with a worm wheel formation 6! on the spindle l3.

Herein the spindle, see Fig. 3, is rotatably supported in the bearing provided in the upper end of the portion l2 and plate H and by the bushing structure 52, the latter being recessed, see Figs. 3 and 4, as at 63 to Permit worm and wheel engagement.

When one of the cranks 55 is rotated one way or the other the spindle structure is correspondingly rotated, and the amount of rotation can be determined as at 3 l--32, see Fig. 2.

Rearwardly of the worm and wheel construction there is provided a clamp, and herein the same includes a lunar segment member 64 that is seated in a slot 65, see Fig. 5, in the bushing 62.

The larger radius surface is adapted to conform to and when properly associated grip the The portion ll includes a transverse bore 66 and one end thereof is closed by cap bolt 67 against which bears a spring 68.

The cam plunger 69 has a cam surface '10 formed in its length and the same includes two 55 slightly angular faces that diverge outwardly as be rotated by the crank 55 as aforesaid to the desired degree of angularity, and when that is accurately attained the member H is reversely rotated into the bore 66 which advances the cam member 69 so that the lunar segment 64 is forced 70 inwardly toward the spindle l3 and frictionally grips the same thereby holding the spindle in the manually adjusted position.

The spindle l3 at its rearward end projects beyond the stock l2ll and this projecting end is externally threaded as at [2. Threaded thereon is an annular member 13 having a T slot channel 14 therein. The member 13 is suitably keyed to the spindle l3 as at 15.

A pair of nuts l6 and Il are slidable in the T slot and each has threaded into it the bolts 18 and 19 respectively. Each bolt head bears on a slot bridging bar 8! and 82 respectively, the same being apertured as at 83 to seat the respective head portion. If desired, the bridging bar may include an extension that rides the throat of the T slot 14 to align these bars.

A suitable hole, not shown,- is provided Whereby the two nuts 15' TI may be introduced intothe head portion of the T slot I l. These two structures constitute stops, the purpose of which will appear more fully hereinafter.

Associated with said stops and between the same; is positioned an elongated member 84', and the same is seated in a groove 85 formed inthe stock portion [2. It is apertured at as and a bolt 8? rigidly secures the locater fixed stop 84 inoverhanging position relative to the tail stock, and the same overhangs the groove or T slot 14 in member l3 and is adapted to be engaged, whenever the spindle is sufii'cien'tly rotated, by one or the other of the adj'ustably mounted stops engaging the adjacent face of the member 34, the overhanging portion being reduced or cut away as at 88.

It will be quite apparent that if an angle of 45 is to be turned from a fixed position with respect to the spindle, the spindle can be rotated to the fixed position by the crank members 55, then the spindle locked by the lunar segment 64', then the stop 8! or 82 brought into engagement with the member 84 and clamped to the spindle in that position. Then the lunar segment lock is released and crank 55 actuated in the proper direction to traverse angularly the desired amount until the desired angularity is obtained, whereupon the segment 54' is again clamped to hold the spindle and the other stop is brought up to engagement with the member 84 and tightened in the T slot. Then the clamp fi l is released and then the spindle can be oscillated to and fro within these limits determined by these stops for progressive grinding within those limits, as more fully set forth hereinafter.

In Figs. 1 and 2 it will be noted that there is supported therein and more particularly, see Fig. 3, in-the coaxial bore [-6 of the spindle I 3 the setting bar 11. This setting bar I! includes four parallel and quadrant positioned key ways or grooves 9'6. At a fixed distance from the forward end thereof is an annular groove 9|. 7

The setting bar has a reduced flatted portion 92, and a micrometer support is of L shape and has the main mounting portion 93 and the offset portion 94, the latter being split as at 95 and provided with the clamp screw 96 to detachably mount the micrometer 91 therein. The screws 98' and 89 detach'ably' anchor the micrometer support upon the setting bar.

The here it of the spindle is provided with the inwardly directed keying pin 00, andthis registers with one of the quadrant positioned key ways when the setting bar is applied to the spindie from the rear end thereof. After being so applied the forward exposed end of the setting bar has the micrometer holding anchored to it. Then when the various measurements are made with the setting bar and micrometer in one position, the setting bar is sufficiently retracted to register the annular groove 91- with the pinv or key" we. and the bar is turned clockwise or coun ter elockwise' and when so turned the key then registers with another one of the elongated slots 9e" and the setting bar is pulled back or projected torwardly, as required, and then the niicrori-iet'ei has measuring axis definitely at 90 to the previous measuring axis.

It is to be noted that the pin or key I 0!] is exaetiy' from the zero position of the spindle, and if the spindle is rotated any predetermined angle iroiii zero, then the two 90 positions of the micrometer will, with respect to the lane of the base ill, be offset that singularity plus 90.

Th e"- operation of so much of the invention as has been previously described is broadly as follows? the workis" rigidly clamped in the work holder. The were is then tilted upon the axis he, see to the desired degree as required tereleaiariee purposes in a cutting tool which is what the Work W in Fig. 2 represents. Then with the micrometer in the verticalposition, as shown in Fig. 1,. the work may be raisedor lowered until the micrometer and engages the same.

If only a minor amount is to be removed the micrometer is backed ed its holder and the top of the tool or work will then correspondingly have to be removed by grinding.

Now' if the sides to be out are to have a predetermined draft, the right" side toward the left and the left sidetoward theright, then the adjustment is made about the axis 26' for the first one, and: following the formation of that draft in the work the other draft can be applied thereto. This would formthe required tool.

Now if the tool were to have a predetermined radius that is of compound character, one being a /4 inch and one being inch, the micrometer would be set for a inch in one position and the work shifted by means of thetool holder to generate a 4 inch radius, and then if a inch radius is to be effected the same operation would be repeated and the result would be the generation of a compound angle or curved surface upon the work.

Following the' work setting operation, as thus described, the micrometer is removed from the setting bar and the setting bar is removed from the spindle, and then the work is brought into registration with a cylindrical rotating diamond grinding wheel if the Work is of the hardness requiring such a wheel.

Then if the carriage upon which the base It is mounted reciprocates to and fro under the dressing wheel aforesaid, the handle 55 is turned causing the spindle to rotate and within the limits determined by the two stops, all while the entire unit is reciprocating with respect to the dressing wheel which is rotating. The result is that when no more stock is removed. from the work when the work is presented to the dressing wheel, that the work has" the desired formation for which the setting up operations have determined and the-toolis completede I From the foregoing therefore it is quite obvious that no inherent know-how or skill beyond that of the average mechanic, and certainly an apprentice machinist, is required to form critical special tools if the master machinist-provides the necessary drawing showing the tool to be generated and giving the proper angular and linear dimensions for which the various parts are to be set in substantiallythe manner previously de-' scribed.

When these successive steps are followed inthe order given on the master sheet or instructions and the work is presented to the dressing wheel until no more stock is removed from the work by that wheel, there can only be one result: a tool that conforms to that designed and required.

It will also be obvious that at any time during the operation of the tool formation that the usual diamond dresser can be applied to the support upon which the base H3 is supported and that support reciprocated to and fro and transverse thereto during dressing wheel operation so that a true cylindrical surface is maintained on that wheel.

It will also be apparent that should the tool require reforming that it can be reset in the work holder and the device adjusted in accordance with the settings initially specified and, for example, another thousandth of an inch or so removed from the tool thereby resulting in a reforming of the tool and only a slight reduction in length of the tool.

The result is that tools can be maintained in their desired state of accuracy and sharpness and for special operations only one tool need be made, and in the event of fracture or loss, misplacement or the like, another can be readily fabricated from the master drawing and instructions.

As previously stated, the present invention eliminates the complete necessity for forming a diamond dressing wheel to the desired shape or conformation and then forming a tool by dressing it in accordance with that conformation with the result that subsequent sharpenings of that tool and/or subsequent replacement tools would progressively depart from the original requisite design.

The economy of the present invention in this latter respect, as distinguished from making individual complementary design diamond dressing wheels, is obvious. The economy incident to the use of a mechanic of average skill over a specialist is also obvious. The use of this simple device for any and all purposes within the range of its capabilities will also be obvious.

The device hereinbefore illustrated is also capable of additional uses, to which reference will now be had.

In Figs. '7 and 8 there is illustrated an adapter that is capable of use with the form of the invention previously illustrated and described, and in Fig. 7, as before, 35 indicates the two parallel side portions of the work holder. S indicates the spacing block required and H indicates a work holder having a hole of predetermined diameter therein which is designated by the numeral 10!.

Extending upwardly from the top face 192 of the holder H is a pin 103. A drill, designated by the letter W, constitutes the work, and thereabove is illustrated in central section the lower peripheral portion of a diamond disc wheel designated by the letters Wl-I. The work herein, in the form of a drill, is rigidly clamped in the bore I02 by means of a headless set screw Hi l.

Rigid with the drill is a collar 105 through which at 66 the drill extends. A headless set screw 1 81 rigidly clamps this collar to the drill. This collar is notched at 108 and two of these notches, diametrically positioned, are provided, the purpose of which will now appear.

The work holder with the work will be adjusted, as previously described, because all drills have a certain relief. Then the arc to be formed will be adjusted as previously described. Then the work supporting table with the invention and the work holder H will be elevated to the dressing wheel, and then the spindle will be oscillated through the angle, shown by the arrows in Fig. 1', and gen erate the quarter-spherical surface or so much thereof as is to be formed in the drill end.

Following the completion of this forming operation the set screw 194 will be unthreaded, the drill and collar elevated, turned axially and replaced so that the shoulder H19 of the other notch 108 will now engage the pin N13.

The drill therefore has been translated 180 and the operation forming the half-spherical surface or generation of the same will be repeated with the result that the drill, when finished, can be used to form hemispherical seats in the ends of bores and the like which are required for certain bearing ball containing fixtures.

Reference will now be had to Figs. 9, etc, wherein there is disclosed the formation of special contour cutting elements such as hobbers and the like.

In said figures WH again indicates the dressing wheel. A in Fig. 9 designates the attachment aving base B and plate portion P. An angle bracket 206 is secured thereto upon which is mounted the motor M driving a flexible shaft S and suitable controlled.

A tertiary base 20! is offset at 292 and secured at 203 to the supplementary base and workholder previously described. Supported in bore 205, see Fig. 10, are the races 2% which rotatably support tubular shaft 2936, same having keyed there to the worm Wheel 20? meshing with worm 2%.; in turn connected as at 239 to the flexible shaft S. This shaft is introduced at 2 ill to housing 2i E.

An arbor 2 l 2 is rotatably supported in the shaft 206. The latter has head 243 at one end and its opposite end mounts retaining means 2M. On arbor 212 is mounted the work W, the arbor hav ing head 215 at one end and shaft clamping means 2 l 6 at the opposite ends.

Thus the work W is adjustably supported the attachment and rotated by motor M. The position of the work, or rather its axis of rotation, is determined by the invention illustrated in Figs. 1 to 6 inclusive.

Contours such as indicated at 0 thus can be formed in the work W, the latter having the re-- cess R therein, or a multiplicity of said recesses as desired.

While the invention has been illustrated and described in great detail in the drawings and foregoin description, the same is to be considered as illustrative and not restrictive in character.

The several modifications described herein as well as others which will readily suggest themselves to persons skilled in this art, all are considered to be within the broad scope of the invention, reference being had to the appended claims.

The invention claimed is:

1. In combination a base having a bore therein, a spindle rotatable in said bore, means for 0scillating said spindle, cooperating spaced stops carried by the base and spindle for limiting spindle oscillation, the spindle havin a laterally directed portion at one end and an end portion projecting from said portion and disposed parallel to the spindle axis, a bracket adjustably and rigidly secured to said spindle end portion for adjustment about an axis transverse to and intersecting the spindle axis, said bracket being offset laterally of the spindle, means securing the bracket and said spindle end portion in pivotally adjusted position, the bracket further having an extension with a pivot portion having an axis offset from the bracket-spindle end portion pivotal axis and transverse thereto and the spindle-base pivotal axis and in a plane parallel to the latter, work holding means pivotally and adjustably secured to the bracket extension pivot portion, and means for securing the Work holding means upon bracket extension in th pivot-ally adjusted posi tion.

2. Structure as defined by claim 1 wherein the spindle includes a bore therethrough which bore is coincident with the axis thereof, a setting bar longitudinally slidable as well as rotatable in the spindle bore, and cooperating key and keyway means between the bar and spindle for limiting bar movement to prescribed limits.

3. Structure as defined by claim 2 wherein there is provided elongated micrometer means,

and an angular support member having an end carried by the bar and the other end carrying the micrometer means so that the longitudinal axis thereof is transverse to the longitudinal axis of the bar and intersects said latter axis.

4. Structure as defined by claim 1 wherein said working holding means comprises a supplementary base, work clamping means slidably supported thereby and movable in a direction parallel to the work holding means-bracket extension pivotal axis, and means for securing the work clamping means in adjusted position upon the supplementary base.

5. Structure as defined by claim 4 wherein the spindle includes a bore therethrough which bore is coincident with the axis thereof, a setting bar longitudinally slidable as well as rotatable in the spindle bore, and cooperating key and keyway means between the bar and spindle for limiting bar movement to prescribed limits.

6. Structure as defined b-y claim 5 wherein there is provided elongated micrometer means, and an angular support member having one end carried by the bar and the other end carrying the micrometer means so that the longitudinal axis thereof is transverse to the longitudinal axis of the bar and intersects said latter axis.

7. In a work holder structure the combination of a base having a bore therein, a work supporting spindle rotatably mounted in the bore in said base and having a peripheral series of gear teeth, a worm rotatably supported by the base and meshing with said teeth, means external of the base and for rotating the worm, a lunar segment lock member within the base and having its greatest radius face confronting the spindle, the base further having another bore therein and transverse to the spindle axis and offset therefrom and slightly spaced from the first mentioned bore, the base having a slot connecting the two last mentioned bores, the slot being arranged for lunar member accommodation, and cam faced means in the second mentioned bore and movable longitudinally therein for segment-spindle locking and unlocking purposes.

8. In a work holder structure the combination of a base having a bore therein, a Work supporting spindle rotatably mounted in the bore in said base and having a peripheral series of gear teeth, a worm rotatably supported by the base and meshing with said teeth, base exposed means external of the base and reversely rotating the worm for spindle oscillation, the spindle including a base exposed portion exposed by the base and having an annular slot of gib-section character, spaced, slot seated, stops adjustably carried by the spindle, a master stop carried by the base and juxtapositioned to the annular slot for slot seated stop engagement, a lunar segment lock member disposed within the base and having its greatest radius face confronting the spindle, the base having a second bore therein which second bore is transverse to the spindle axis and offset therefrom and slightly spaced from the spindle receivable base bore, the base having a second slot connecting the two last mentioned bores for lunar member accommodation, and cam faced means in said second mentioned transverse slot and movable longitudinally therein for segmentspindle locking and unlocking purposes.

9. Structure as defined by claim 1 wherein said work holding means compr ses a member having a socket transverse to and offset from the immediate pivotal axis of said work holding means, said socket being arranged for drill reception, means for locking the drill in the socket, a stop carried by said member, a collar having its periphery provided with a plurality of notches, the collar further having a bore therethrough and of drill size, and means on the collar for locking same to the drill, the notches being equally spaced and in number equal to the cutting faces of the drill, the last mentioned locking means limiting socket seating of the drill shank, initial setting of the drill through said structure being efiected with the stop engaging the collar at one notch, and a successive setting of the drill being effected by stop engagement with a successive notch of the collar.

10. Structure as defined by claim 1 wherein the work holding means comprises a socket providing means having its socket axis parallel to and offset from the pivotal axis between the Work holding means and the bracket extension, an arbor rotatably supported by the said socket means and adapted for rigid connection to the work, and means for rotating said arbor while the work holding means is oscillated.

11. Structure as defined by claim 10 wherein the rotating means comprise a motor rigid with base, and a flexible shaft rotatable by the motor.

12. Structure as defined by claim 11 wherein a worm is driven by the shaft, and a worm Wheel is coaxial with the arbor.

13. Structure as defined by claim 12 wherein a tubular shaft is interposed between the arbor and socket providing means and rotatably supported thereby and rigid with the worm wheel.

ALONZO K. ELLIOTT. THEODORE T. MUNN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,835,328 Parsons Dec. 8, 1931 1,965,002 Richer July 3, 1934 2,212,855 Chittenden Aug. 27, 1940 2,213,756 Zwick Sept. 3, 1940 2,362,873 Wessman Nov. 14, 1944 2,400,826 Jakobsen May 21, 1946 FOREIGN PATENTS Number Country Date 370,648 Germany Mar. 5, 1923 518,146 France Dec. 27, 1920

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