US 2671484 A
Description (OCR text may contain errors)
March 9, 1954 F Q CLARK 2,671,484
MAGNETIC TOOL Filed Nov. 18, 1948 2 Sheets-Sheet 1 INVENToR.
March 9, 1954 F G, CLARK 2,671,484
MAGNETIC TOOL Filed NOV. 1.8, 1948 2 Sheets-Sheet 2 WOR.
Patented Mar. 9, 1954 .AT-ENT OFFICE i -MAGNETIof'rooL .I Frederick G. Qlark; Buffalo, N. Y.; assignor f of oneehalf -to Wade Stevenson, BuHalo, N. Y.
"Applicltion"Nove'll'lber 18, 1948,"Serial'No. 60,795
This invention relates tom'agnetictools for applying fasteners such as screws, bolts,nails,^-rivets, or the like, and for holding such fastenerson the tool prior to and during the starting' of therdriving of the same into their operative positions.
One of the objects of this invention `is to provide a tool of this kind of'improved construction by means of whicha fastener will be securelyrheld prior to and during the? preliminary driving of the same into its operative position. A further object of this invention isrto provide-a tool of this type in which asmallhorseshoe type of magnet of high magnetic force is incorporated in the tool varid inwhich the driving implement is normally `pointed out hereinafter in connection withI the appended claim.
In the accompanying drawings: Y
Fig. 1 Vis `an elevation,` partly in section, of-v a magnetic screwdriver embodying this invention.
Fig. 2 is a bottom planvview thereof, showing some of the parts in different positions.
Fig. 3 is an end View thereof.
Fig. 4 is a longitudinalA central sectional view thereof, on lined- 4 Fig. 3.
Fig. 5 is a-transverse sectional view thereof,.on line 5 5, Fig. 4. y
Fig. 6 is a central sectional elevation of a magnetic tool for driving nai-ls, rivetsand thelike.
Fig. 7 is an elevation of a power drivenfscrewdriver embodying. a modified vform of'fmy'iin'vention.
Fig. 8 is a fragmentary longitudinal/central sectional view thereof,lon' an 'enlargedfscale I Referring to the` particular-embodiment ofthe invention shown in Figs. 1 to'5, VIII represents the shank of a screw driver. Only a portion .fof ,this
shank is shown .and the same V`may .befrotated either manually or by power. Thisf'shank'iis provider-1- atthe outer end-thereof with.a ..po'rtion",9 of reduced diameterwhich-terminates atv its outer end in a driving'member, such for" example as a screwdriver' bit II. The portiori S'f reduc'ddiameter may be formed integral withthe "shank I0 .and forms ashoild'erIZ `witli-`the'fshak I0.
The end I Irof the driving member'may besofany other' shape to cooperate with the heads of the fasteners with which the tool is to vbe used.
`I 4 represents a sleeve or shell, one end offwhieh is' slidably mounted on the shank I0 to moveto a limited extent lengthwise thereof and theother end of which supports a magnet I5. Thisemagnet is preferably made of an alloy^which maylbe highly magnetized--and is of hollow cylindricall'or tubular form. The outer end of --the-magnetvis bifurcated by means of aslot or groove IE-extending diametrically of the-magnet-fand:-dividing the outer end thereof intoy two projectionsv I 8 and IS which form rthe two poles of the magnet.
The outer end faces of the magnet poleslland l I9 may beA shaped in any desiredmannervto best cooperate with the head of a screw or bolt-to-hold `.thesame substantially inaxial alinementwith Vthe driving member or bit.
ple -as the round-headed bolts or-fsc'rewsa' 22' 'and 23 shown'in broken lines 'in Figs; 1, 'Ziand 4. "It
will be understood'however, thatthe'outefface of the magnet'may be ofv any suitable' or desired shape to enable it to best hold the headsf the fasteners with which the toolis toc'ooperate.
The sleeve I4 constitutes a"magneth'o1der*by means of which the magnet may be'moved'toward theshank I0 to permit the bit to'move into engagement withI the fastener. iThe' magnet holder may be of other suitable form.
The magnet may be 'secured inA its operative 'relation to the sleeve ormagnet holderinany suitable or desired manner, and in the constructi'on shown, the shell is provided Withinteg'ral lips 25 which extend inwardly intofengag'em'ent with the inner ends of the grooves or recesses I6 If'it is desiredito removethe end 'ofthe sleeve,fso that the magnetmaybIr-e- 'placed by another magnet. The' shell IlI'iis made nless of a "non-'magnetic material, such LAas ste'el, bronze, or'the'like; which'rwilln'otomnia low resistance path forl'the'linesfoffor frmone jpoleof the magnet to the 'other',iand=wvhich will therefore not detractfromlthe strengthfor force "of the magnet.
In order'to'- avoid-short-circuiti-ng thel-lin'e *fof "force'ffrom one' magneucffpiefto-theiethersand thus have most of these lines of force available to pass through the head of the fastener to more securely hold the same while the fastener is being positioned in correct relation to the hole in the work into which the fastener is to be driven, I preferably provide means for normally holding the sleeve I4 and the magnet arranged thereon in such position that the end of the bit I I will not be located between the end portions of the poles of the magnet and will be located normally within said magnet and spaced from the outer end thereof. Any suitable or desired means may be provided for this purpose, and which also permit the bit to pass further into the hollow cylindrical magnet and projects to a point beyond the innermost limit of the face of the magnet and into engagement with the slot or recess in the fastener after the same has been correctly positioned on the work. In the construction, shown by way of example, I provide a coil spring 3B, one end of which engages the inner end of the magnet I5 and the other end of which may exert a pressure against the shank IIJ. This may be accomplished, for example, by providing on the reduced shank portion 9 a ring or washer 3l bearing against the shoulder I2 of the shank and against which the spring 3l) may press. The ring or washer 3I may, consequently, slide lengthwise of the shank portion 9 into engagement with the shoulder I2. The portion of the sleeve I4 slidably engaging the shank I is preferably of somewhat smaller internal diameter than the remaining portion of the sleeve, thus forming a shoulder 34 which may abut against the ring or washer 3i to limit the extent to which the spring 3G may expand.
Suitable means are provided for retaining the sleeve in operative relation to the shank I0 and the bit II and for permitting limited sliding of the sleeve or magnet holder I4 on the shank. For this purpose the sleeve is provided with a slot 31 and the shank I0 has a pin or set screw 38 secured thereto and extending outwardly therefrom into the slot 31. Consequently, the spring 3D will normally hold the magnet holder or sleeve in its outer position as shown in Figs. 2 and 4, in which the end of the bit will be spaced from the projections or poles I8 and I9. Consequently, it
" will be obvious that by means of this construction;
the driving member may be made of a grade of steel, such as heretofore used for driving members of various types and which is magnetic, and more durable than non-magnetic materials which are at present available. By making the' pin or set screw 38 removable, the sleeve or magnet holder I4 and the magnet mounted thereon may be released from the driving member so that the driving member may be replaced when worn out or broken.
When the screwdriver bit is of the type commonly used for screws or bolts with slotted heads, it is desirable to position the bit relatively to the poles of the magnet in such a manner that the flat end of the bit will extend substantially parallel with the transverse groove or recess I6 in the magnet as clearly shown in Figs. l to 4 so that the fastener engaging end of the screwdriver bit will be spaced from the poles of the magnet by the maximum air gap. When arranged in this position, the screwdriver bit will have very little eiect in reducing the magnetic force available to hold the screw or other fastener on the tool. This positioning of the bit relatively to rni 4 of the construction described by arranging the slot 31 and pin or set screw 38 in such relation to the shank ID so that the flat sides of the screwdriver bit II will face the poles of the magnet.
In the particular construction shown, the shank I0 is of hexagonal cross section and the bore in the portion of the shell I4 which engages the shank is of similar hexagonal form so that rotation of the shell and shank relatively to each other is prevented, thus supplementing the action of the pin or set screw 38 and slot 31, which also serve to prevent turning of the sleeve relatively to the shank. The shank may, however, be of circular cross section, if desired. Any other means for preventing relative rotation of the shell and shank may, of course, be provided if desired.
When the parts are in their normal positions, the spring 30 will hold the sleeve or magnet holder I4 in its outer position, as clearly shown in Fig. 4, so that the end of the bit II is spaced from the poles I8 and I9 of the magnet. When the parts are in this position, a screw or bolt having a slotted head will be rigidly held by the magnet in such a manner that the screw or bolt may be moved into correct relation to the hole into which it is to be screwed, whereupon pressure may be exerted on the shank I0 in a direction toward the fastener and by simultaneously turning the shank, the bit II will seat itself in the slot 35 or other recess in the head of the screw or bolt. When this driving connection has been established, further rotation of the shank I0 will cause the screw or bolt to be screwed into its operative position. Once the screw or bolt is started, the holding force of the magnet is no longer required and when the screw or bolt enters the work approximately into its nal position, the head of the same may be withdrawn from the magnet as the end of the sleeve I4 contacts with the work.
It may at times be desired to provide additional means for holding the screw or bolt in axial alinement with the shank I0 in order to facilitate starting the bolt or screw in the hole into which it is to be screwed, and this can be accomplished by so positioning the screwdriver bit relatively to the magnet that the bit will enter the slot or other recess in the head of the fastener while the same is held by the magnet. For this purpose, I have shown a cam member in the form of a split 'ring 40 rotatably arranged in an annular recess 4I in the outer surface of the sleeve I4. I'he cam ring is provided at one edge thereof with a slot or recess 42 into which the pin or set screw 38 may enter. Consequently, when the pin is in the inner end portion of the slot or recess 42, ,as shown in Fig. 2, the sleeve I4 will be held by the spring 30 in its outer position so that the driving member or bit i I will be spaced from the poles of the magnet. By moving the sleeve I4 to the left from the position shown in Figs. 2 and 4 and turning the split ring 40 relatively to the pin 38 so that the pin rests on the outer edge portion of the ring 4U, as shown in Fig. l, the sleeve is so positioned that the bit II will project between the poles of the magnet to enter the slot in the fastener while the same is held by the magnet. Under these conditions, the fastener will be held substantially coaxial with the shank I0 and sleeve I4 and can, consequently, be readily inserted into the hole into which it is to be screwed even while the shank is rotating. Since the fiat faces of the bit will extend mevr-gsi pole'piecesf'it `willsnotreduce'the magnetici force acting vonthe fastenerL 'to i any l'na'terialL extent. Any other means for `:holding Athe sleevein retarded position against vthe action-of the spring 30 'maybe provided; if desired. By'making Vthe 'sidesf 42 of the slot so that theydivergeas shown 41 is to be handled'by means of the screwdriver,
they sleeve I4 can be moved into the-position shownr inFig. l, whereupon` thefastener'ZZwill be' held not only by the magnetic force; butwill also be correctly positioned and held in substantially axial alinement withthe shank I by means of the bit I l.
In Fig. 6, I have illustrated my invention adapted to a tool for driving nails,tacks, rivets, or the like. In this construction, 45 represents a portion of the shank of the tool 46 and magnet holder which may be' in the form of a sleeve orA shell, one end of which is slidably vmounted on the shaft 45 and in the other end of `which a hollow cylindrical horseshoe Imagnet-4`i is mounted. The sleeve 46 is made of non-magnetic material. This magnet also has a diametrically extending groove orV recess s'dividing the outer end of the m-agnet into two projectionswhich form the poles of the magnet, and the sleeve may be provided at opposite sides:thereof with'lips 49 extending into the groove or slot 48 to prevent outward movement of the magnet through the open end of sleeve 45. The portion of the sleeve 46 which engages the shank 45 is also made of greater thickness as described in Figs. 1 to 5, thus forming a shoulder 50. The sleeve 45 may be suitably limited in its motion relatively to the shank, for example, by means of a pin or set screw 52 secured to the shank and extending into a slot 53 in the sleeve 46. A shank 45 has an end portion 54 of reduced diameter which also forms a shoulder 55 at its juncture with the main portion of the shank 45, and this reduced portion 54, which corresponds to the bit ll shown in Figs. l to 5, constitutes the driving member of the tool. The sleeve 46 is also made of non-magnetic material, but the driving part 54 of the shank may be of hardened steel. Means are, therefore, provided for normally supporting the magnet 4l in such relation to the driving part 54 that the driving part will not form a short path for the magnetic flux from one pole to the other, and for this purpose, a spring 57 is provided within the sleeve 45, one end of the spring engaging the inner end of the magnet 4'! and the other end engaging the ring or washer 58 which engages the shoulder 55 of the shank and which also engages the shoulder 55 of the sleeve when the same is in its outer position in which the poles of the magnet are spaced from the driving member 54.
In the operation of this device a nail, rivet or like fastener 60 having a head 6l may be held on the tool by causing the head 6| to contact with the poles of the magnet 41 so that the fastening member may be held in substantially axial alinement with the shank or shaft 45 by means of the magnet. When force is applied through the shank 45 in the direction toward the fastening member, the driving member 54 iftviueiigageftneheadfof-themen?or'rivetfand'thes drivethe: same-intoitsioperative position.
rect positionj-but afterthe'firstblowthefmagnet "will hold' thetool in" correcirelatiorto theastener; thusE facilitating 'thedriving" offthef-fastener jinto 'itslnal position.
I In" Figs. vr and? a; I vhave shown-my improvements applied to a powerf l driven* screwdriver *fof scratch any work-with whichY it comes into fc'o'ntact, the sleeve being madeof` non-magnetic-ma- Aterial. In this construotion=B52-representsl the shell or housingof afmo'tor ofany suitable type, not shown, Vwhich I rotates faiY im'ember 57- provided l"with a clutch or couplingof any-suitable type 301 projecting f from one 'fendi-thereof within'i which the sleeve'lv is slidably-inounted. hollowcylindrical horseshoe magnet *Smay 'be suitably tionshown, the o'uterend off-thef'sleeve :hasta boreof reduced diameter withinwhichaimaget l2 of this type may be secured in any suitable manner, for example, by driving the magnet into the outer portion of the bore of the sleeve 65.
In order to so space the magnet with reference to the driving member or bit 68, that this member will not cause magnetic lines of force to pass from one pole of the magnet to the other through the bit of the driving member, means are provided for normally spacing the magnet relatively to the end of the -driving member so that this end will normally not extend between the two poles. For this purpose the sleeve 65, which is slidably mounted on the tubular extension 10 of the motor housing, is normally held in its outer position .by means of a coil spring 13 one end of which engages the inner end of an enlarged portion 'I4 of the sleeve 65. The other end of the spring engages an inwardly extending flange or shoulder 15 of the motor housing. The sliding movement of the sleeve 65 relatively to the motor housing is preferably limited, for example, by means of a slot l1 extending lengthwise in the enlarged portion 14 of the sleeve 65, and a screw or pin 18 which extends through an aperture in the extension 'l0 of the motor housing and into the slot Tl. The ends of the slot limit the extent to which the sleeve may move relatively to the driving member or bit 68 and also prevents rotation of the sleeve relatively to the motor housing.
In the operation of this device, the head of a screw, bolt or other fastener is placed into engagement with the outer end of the magnet 12 so that it will be securely but removably supported thereby. The fastener is then positioned at the hole in the work in which it is t0 be driven and when so positioned, pressure is exerted on the motor housing 66, thus causing the driving member or bit 68 to engage the slot in the head of the fastener and turn the same for moving it into its nal operative position.
Magnetic Screwdrivers of this type have the advantage that it is not necessary to manually start the screw or other fastener in the hole in which it is to be driven. Tools of this type, therefore, not only save time in applying fasteners in positions which are relatively inaccessible, but also facilitate and expedite the application of fasteners under any conditions.
By means of the constructions described, driving members or bits of conventional construction and materials commonly used in connection with tools of this type may be employed without weakening the force exerted by the magnet on the fastener. Consequently, the driving members may be made of the desired grade of steel without consideration if its ability to conduct magnetic flux, and when my improvements are used in connection with poweroperated Screwdrivers, the same screwdriver bits formerly employed may be used. The construction described also has the advantage that the magnet holder or sleeve extends slightly beyond the outer end of the magnet so as to facilitate the positioning of the fasteners on the tool and to protect the magnet against damage by contact or impact with other objects.
The term non-magnetic is herein used in practical sense to designate materials of very low magnetic permeability.
It will be understood that various changes in the details, materials, and arrangements of parts which have been herein described and illustrated in order to explain the nature of the invention, may be made by those skilled in the art within the principle and scope of the invention, as expressed in the appended claim.
I claim as my invention:
A tool for applying fasteners comprising a shank having a driving end, a non-magnetic sleeve slideable on said shank and encasing said driving end, a hollow cylindrical magnet coaxially aligned with the axis of said shank secured to the inside of said sleeve and polarized across a face, said face facing in the direction of the object to be held, a spring acting against said sleeve to maintain the magnet in a. position relative to said driving end, in which position said driving end is located Within said magnet and spaced from the outer end thereof, and upon retraction of said sleeve, said driving end projects to a point beyond the innermost limit of said face of sai-d magnet, said sleeve having a portion extending beyond said face of the magnet having inner walls substantially parallel to the axis of said shank.
FREDERICK G. CLARK.
References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 935,256 Heard Sept. 28, 1909 1,265,113 Reimer et al. May 7, 1918 1,501,695 Wurdack July 15, 1924 1,645,753 Hanson Oct. 18, 1927 1,855,456 Miller Apr. 26, 1932 2,258,861l Park et a1. Oct. 14, 1941 2,260,055 Reardon Oct. 21, 1941