US2939211A

US2939211A - High-leverage tool

Info

Publication number: US2939211A
Application number: US762011A
Authority: US
Inventors: Albert G Daniels
Original assignee: James R Kearney Corp
Current assignee: James R Kearney Corp
Priority date: 1958-09-19
Filing date: 1958-09-19
Publication date: 1960-06-07
Anticipated expiration: 1977-06-07

Description

June 7, 1960 A. G. DANIELS 2,939,211

HIGH-LEVERAGE TOOL Filed Sept. 19, 1958 3 Sheets-Sheet l I bLcMeM73Zder$7Z71r June 7, 1960 A. G. DANIELS HIGH-LEVERAGE TOOL 3 Sheets-Sheet 2 Filed Sept. 19, 1958 June 7, 1960 A. cs. DANIELS 2,939,211

HIGH-LEVERAGE TOOL Filed Sept. 19, 1958 3 Sheets-Sheet 3 FlG.6

United States Patent HIGH-LEVERAGE TOOL Albert G. Daniels, Winnsboro, S.C., assignor, by mesne assignments, to James R. Kearney Corporation, St. Louis, Mo., a corporation of Delaware Filed Sept. 19, 1958, Ser- No. 762,011

1 Claim. (Cl. 30-187) This invention concerns high-leverage tools and particularly tools of the type in which a pair of dies or cutters are brought together with considerable force to eifectuate a forming or cutting operation on metal objects of very heavy gauge. The simplicity and great mechanical advantage of my tool makes it particularly suitable for use as a hand tool for field work in the electrical industry, but the principle of the tool is applicable equally well to power driven tools for any use in which highleverage is desirable.

High-leverage tools which employ either gear-reduction principles, a principle of cam action, or a lever principle are well known in the art; but as far as I am aware, the unique combination of gear-reduction, cam, and lever action in a single mechanical power transmission taught herein has not previously beenused. In addition, my gear-cam-lever arrangement has the advantage that the tool may be easily preset by hand to the point where the forming or cutting jaws engage the Work-piece, without the necessity of turning the operating crank; that the depth of the cut or the extent of deformation is easily' and accurately adjustable; and that when the cutting or forming operation is completed, the tool will automatically snap back into a position where it is ready to begin the next forming or cutting operation.

It is therefore an object of my invention to provide a simple high-leverage forming or cutting tool which achieves a maximum mechanical advantage with a minimum of parts.

It is a further object of my invention to provide a high-leverage tool in which the point of beginning of the closing operation can be easily and rapidly set by hand to accommodate work-pieces of varying sizes.

It is a still further object of my invention to provide a simple high-leverage mechanism which will automatically reset itself to its starting position at the end of each operation.

It is still another object of my invention to provide a high-leverage tool in which the amount of maximum closure of the jaws is easily and accurately adjustable.

It is finally yet another object of my invention to provide a high-leverage mechanism in which the average theoretical mechanical advantage can be varied in a predeterminable pattern throughout its cycle of operation.

Other features of the invention will be in part apparent from and in part pointed out in the following detailed description taken in connection with the accompanying drawings, in which:

Fig. l is a side view of a hand tool manufactured according to my invention;

Fig. 2 is a top view of the same tool;

' Fig.3 is a side view of an alternative embodiment of the toolof my invention suitable for both manual and ice Fig. 6 shows the efiect of using a conventional gear train in the tool of Figs. 1 through 4;

Fig. 7 shows a type of gear train suitable for use in the tool of Figs. 1 through 4;

Fig. 8 shows an alternative type of gear train also suitable for use in the tool of Figs. 1 through 4; and

Fig. 9 is a detail of the cam-and-roller arrangement of Figs. 1 through 4.

Basically the tool of my invention consists of a pair of jaws which may carry any desired cutting or forming head. Each jaw tapers at its base into an elongate arm, the two arms being journaled between a pair of rigid cross-members in such a fashion that the portions of the arms extending on the opposite side of the cross-members from the heads constitute a pair of levers to provide a first mechanical advantage. A spring is provided to pull the lever portions of the arms together so as to bias the jaws of the tool into the open position. In the operation of the tool, the jaws areclosed against the spring bias by rotating a pinion, the axis of which is operatively fixed with respect to the first jaw, against the toothed surface of a generally spiral-shaped cam which is rotatably attached to the lever operating the second jaw. This arrangement takes advantage not only of the maximum leverage available, but it also has the further advantage that the amount of mechanical advantage provided by the tool (i.e. the ratio between the force exerted by the operator on the tool and the force exerted by the tool on the workpiece).at any givenaperture of the jaws is readily predeterminable by the appropriate shaping of the cam, as will hereinafter appear.

The shape of the cam is so designed that when it reaches a pre-set position (e.g. whenthe jaws are completely closed), the pinion will ride over the edge of the cam, whereupon the jaws will open under the action of the spring and the pinion will again engage the cam at V so that the cam and pinion may be reversely rotated by hand without the necessity of moving the operating crank. The drop-oft face of the cam provides a highly suitable surface to be engaged by the operators finger in accomplishing this process.

An interesting feature of my invention is the fact that the average theoretical mechanical advantage of my tool (taking the distance travelled by the crank handle when the pinion is turned through the are between two adjacent teeth as one unit) at any given point during the closing operation can be pre-set at will by appropriate shaping of the cam. This results from the fact that the amount of travel of the jaws for the arc of the pinion lying between the apex of one tooth and the apex of the next is directly proportional to the increase in distance between the axis of rotation of the cam and the bottom of the grooves on the cam periphery which the above-mentioned adjoining teeth of the pinion engage (Fig. 9). In other words, if the amount of travel of the jaws corresponding to a rotation of the pinion from the apex of one tooth (A in Fig. 9) to the apex of the next-(B in Fig. 9) is designated as l/M, then k'being a constant of proportionality and dr the increase in radius of the cam from the bottom .of the groove-:-

engaging tooth A tothe bottom of the groove engaging tooth B. The"bite'of my tool is not uniform through-F Patented June 7, 1960 out the closing-cycleforreasons discussed hereafter. a It reaches amaximum whilethe apex of a-tooth of the-- from the center of its axis 1 of rotation to the bottom ;of

the groove of the cant-increases considerably from groove to groove in the early portion of the travel-of the pinion,

comparatively-littleduring-fliemedian part of "its-travel, 7 and considerably'again-toward=the end of its travel, the"- tool can be made tobite-relativelyquickly (low average theoretical mechanieal'advantage)-in the beginning of it's cutting" cycle when the" object to 'be cut isstill freadily dea formable; slower-but; more force (higher average theoretical -mechani cal advantage) {in {the median part of? the cut; where the' workpiece opposes the maximumro sistance, and quickly-again at the endofthe cutting cycle where portionsof the workpiece (such'as'the outer strands i of a stranded ;wir e) are-already cu-t and 'ofier no more' resistance. On the*other hand; of course,"it-is' possible to shape the caminsuch a manner that the average:theoreti-' cal' mechanical' advantage of thetool remains uniform throughout thecutting cycle, or 'in any other way that i might be desirable under any practical conditions that maybe encountered: I 7

It" Willbereadily apparent from the preceding parat the point of contactprather than a tangential turning. force as is encountered in 'a conventional gear train. It is therefore, necessarydo "provide geareteethof such a configurationthat th'e'compressive force is absorbed by: the tooth in'a direction perpendicular to the peripheries or I the pinion and the cam; Aiprefei'redembodiment of a j pinion" and cam meeting; this requirement is shown in Figure 7 and Will'be discussed hereafter.

Referring now to Fig. l, the tool of my invention is generally shown at 10.1 The tool it is provided with a.

hand1e'12 which 'may be of any suitable shape Extending; up wardly from the handle 12 is a member 14 on Whicharemounteda shaft 16 carrying the pinion'18- and the operating crank' 2i and. a shaft 2201; which is journaled the-lever arm'portion 24 of'the first jaw 26. A set screw ZSequipped. with a lock is, provided to permit adjustment ofthe jaw 26 with respect to member 14.

This adjustment makes it-possible to set the degree of' closure of the jaws at which the pinion 18 will ride over the edgeof the'cam'32a The cam 32 is provided with a smooth drop-offiface 34 and with gear teeth36along the remainder of its periphery. The cam 32 is journaled on a shaft 38 mounted at the end of lever portion 40 of the second jaw 42." The jaws 26'and 42 are journaled respectively on shafts 44 and 46 which'are-mounted in the rigid cross-members 48. A pairof springs 54) connects the lever portion 40 of jaw 42 withthe member 14 so that the force exerted by the spring 50 is transmitted through the cross-members 48 and causes the lever portion 24 of jaw 26' to rest firmly against set screw 28.

'The pinionr18 is turned by the crank .21 which is;

provide a rigid connection between crank20 and pinion,

130x 68. The pinion 18"in this emb odiment is keyed to theshaft-- 16-and is driven by a gear 62-also r I operation, shaft 66 can berotated by a gear 72 keyed to it, the gear 72 beinggsin turmdriven by, pinion 74 attached to shaft 76 which protrudes from the gear box 58 and may be engagedf'b'y 'theichuck" 78 of any" appropriate" power drive means, ,asillustrated,schematicallyat .802

7 Figs. 5, 6, 7, and 8'il1ustr'ate a problem encounter'ed'in I '5 the design crane geanteethof the:pi-nioni and cam, and

I graph that the force; exerted'betwe'emthe pinion andthe cam is-predominantly a'cornpressive forceacting perpen-' diculalily to' the rpeiipheries'of thepinion and the carpet l8lwhen the crank '20 is turned clockwise, but to disengage f the basic structure of the jaws 26 andAZ and of their,

operating mechanism has been retained. j In; addition, however, a gear box 58 has been mounted on the arm egate 26;; p ge; 6B'jiSLfiXedlYQattachedto;

some possible solutions. therefor. An enlarged view of a conventional gear train is shown inFig. 5. It will be noted that the active stress 82-84 of the gear teeth takes place in a direction almost tangential to the gears. If the usefulforce tobetransmitted is a tangential rotational, on'e,;,the totalacti've stress,82 84' on the gearteeth is'j flsec qt, which is only, slightly greater than the useful tangential'forcef In my high-leveragesystem,w however, the .useidl 'ir'orce is substantially radial, the.tan-. gential component 'jbeing negligible as far as the active stress, ist-concernedl Consequently, if"conventional gear teeth ,wer'erusedin, my system (Fig. 6), theactive stress.

I 8 2 84 on each side of tooth 86 would be or break. even -the strongest.teeth. "Consequently, .it'is:

.necessary to. shape the teethlofimy pinion and cam. in

such a manner I(Fig.. 7.) .that each .tooth 86.01 thepinion T 'presentsualarge area ofl'contact.to. the-corresponding;

groove 88in the cant while contacting the. Portion of".

thegroove. 88 in which .theItooth.8 6-is liftedb y theinaa creased radius lot the cam... The portion 90Iof.the.gro,ove l 88' soshdpedastohdv a generally tangentialtcurvedl.

surface which espousesthe complementarily shapedapex. of tooth 86 at the critical point ofmaximunnforcetrans-a mission. Q i I i Comparatively little; force is. exerted on the pinion and cam during all. phases of 'theirrotation other than the :phase duringiwhich the lifting of .tooth 86 byportion} .90 .of V groove .88. actually effects v.a cutting or forma. ing stroke. Therefore, and in order to preventover ridingofthe gears during the.idle. phase of the turning motion, the teeth; may beshapedhasshown in: Fig.. 8,.where the-numeralBi again 'designatesithe active. lifting portion of,groove 88,=.and-92 designates a.substantially radial surface of groove 88.which: is engaged by tooth .86 during .the idle rotational-, phase of the.- movernent of the pinion'and cam.

Obviously, other shapes of teeth satisfying thebasic. requirementof efiective force transmission without excessive strain ontheteethmay beused on the pinion and cam, and thepabove .descriptionis not intended to be,

of some practical embodiments-of my invention.

In operation, .a workpiece-is positioned betweensthe jaws 26and 42. and'the jaws are closed upon .the.avorkpieceby manually,rotating cam1 32 in acounterclockwise direction until'the jaws engagethe workpiece. Thecrank 20 ,(or,the-apprppriatmmotive means intthe; alternative.

embodiment of Figs. '3 and 4) is the-nz turned so ,asto impart .a .clqc'kwise motiong to'apinion -18; ;Pinion.'l8 engages the toothed edge 36 of cam.32 andi-thereby causes; cam 32 to rotate intat-cpunter-clockwise.idirectiona This rotation of, cam 32 ,aboutashaft. 38, causes, the. spoint x'pf assme t "P n 1 mm he g 1 6 .0.fwami: .2;: to become increasingly spaced from.-..the.-;s haft;38,-.-;thus

- causing the arin portionsA tl andv 24 to separate; which ir tumacaus'es thejaws 26,and.421cc:come-tqgetherarAs explained previously herein, the instantaneous speed closing of the

jaws

26 and 42 at any given point for any given constant speed of pinion 18 is predetermined by the shape of the cam 32. When the jaws have reached the position predetermined by the setting of the set screw 28, the pinion 18 will ride off the end of the toothed portion of 36 of cam 32 and will slide along the smooth face 34 of cam 36 to its original position as the arm portions 24 and 40 are drawn together under the influence of spring 50, thus opening the jaws. The tool is thereupon instantly ready for positioning about the next workpiece and repeating the operation. Y

It will be seen from the above description that I have provided a simple and highly efiicient high-leverage tool which combines in a single simple and rugged mechanism all the advantages of a gear reducer, cam drive, and lever. In addition, my tool has the advantage that the amount of maximum closure of the jaws can be readily and accurately adjusted by a single set screw to suit the necessities of the work, and that the jaws can easily and quickly be closed into contact with the workpiece by hand so as to avoid any unnecessary turning of the operating crank. The use of a ratchet between the crank and the pinion further makes possible the operation of the tool in close quarters where complete rotation of the crank is not feasible. My tool also has the desirable feature that the average theoretical mechanical advantage of the tool may be continuously changed as the jaws close upon the workpiece, so as, for example, to close relatively quickly while little pressure is required at the beginning of the operation, and to increase the pressure exertable upon the workpiece at the expense of speed as the resistance of the workpiece against deformation increases. Finally, the fact that all the operating parts of my tool are freely movable with respect to each other makes my tool highly impervious to mechanical damage or abuse, particularly where the gear teeth and the adjustment of the jaws are concerned.

It will be readily understood that the embodiments described above are merely illustrative, and that my invention may be embodied in numerous difierent forms for different uses. For example, if it were desired to limit the pressure exertable on the workpiece, the gear engagement between the pinion and the spiral cam may be replaced by a friction engagement such as might be obtained, for example, by making the surface of the pinion and the periphery of the cam smooth and coating them with rubber or other suitable materials. Also, by mechanical expedients such as, for example, mounting jaw 42 on arm 24 and jaw 26 on arm 40, in the manner of an ordinary pair of pliers, my tool may be used as a spreading tool rather than a compression tool. Finally, the power drive means may be permanently incorporated into the tool, rather than a separate unit as described herein. I therefore do not Wish to limit myself by the above description, but only by the scope of the following claim.

Having thus described the invention, what is claimed and described to be secured by Letters Patent is:

A high-leverage tool comprising a pair of jaws carrying Working heads adapted to engage a workpiece, said jaws being mounted for movement with respect to each other, each of said jaws having an arm portion, a lever member forming a continuation of one of said arm portions, a pivot between said arm portion and said lever member, stop means for limiting the rotation of said lever member on said arm portion of said first of said jaws, a spiral-shaped cam rotatably mounted on the arm portion of the other of said jaws, and drive means mounted on said lever member and engaging the periphery of said spiral-shaped cam to impart rotation thereto.

References ited in the file of this patent UNITED STATES PATENTS 277,988 Burk May 22, 1883 463,977 Allen Nov. 24, 1891 996,777 Linnartz July 4, 1911 1,071,687 Becklin Sept. 2, 1913 1,317,758 Dicop Oct. 7, 1919 1,530,920 Waite Mar. 24, 1925