US2665597A - Expansible anchor - Google Patents

Description

Jan. 12, 1954 J. L. HILL EXPANSIBLE ANCHOR Filed March 8, 1951 (itt neg JAMES L. HILL "l ESI,

' this assuring Patented Jan. 12, 1954 James L. Hill, Wichita,

tion of Delaware Kans., assgnor to Boeing Airplane Company,.Wichita, Kans., a, corpora-- Application March s, 1951 serial N0..214,44a

(c1. vr-pzvi 3 Claims. 1.

This invention relates toa special tool for aide ing in the countersinking of holes in heavy gage metal, and more particularly to an expansible anchor which can be passed through a hole to be countersunk, automatically expanded on the opposite side of the workpiece to prevent its withdrawal therefrom, and thus used as an anchor for the application of the required axial force to the countersinking bit. The type of countersinking tool with which the specific an` chor constituting the present invention may be used is fully described and illustrated in my4 pending patent application Serial No. 199,071, iiled December 4, 1950. This typeof countersinking tool includes an axially bored countersinking bit which rotates about .an axially movable draw bar Which extends outward beyond the working end of the bit, and to which an axial co-untersinking force may be applied mechanically.

It is an object of this invention to provide an anchor suitable for installation on the free end panded, the drawbar and countersink bit centered with relation to the hole, and the counterof the drawbar of such a countersinking tool to aid in -forcing the countersink bit axially into ther workpiece to accomplish the countersinking cut.

It is a further object toprovide an anchor ofA this type which utilizes the principle of the vvedgev or inclined surface, and which`is expanded in diameter by a slight axial movement of its drawbar in a direction opposite the direction ofV its original insertion into a Another object is to provide an anchor which, when expanded, will perfectly center the draw bar with relation to the hole to be countersunk,

hole -in a workpiece.

sink cut and the hole in the workpiece.

Another object of this invention is to provide an anchor which Will automatically contract to its normal diameter when it is moved away from anchoring contactl with the workpiece surface, thus permitting it to be easily withdrawn through the hole after the countersinking cut has been made.

The invention, together with other objects, will be more clearly understood when the following description is read in connection. with the ac.u companying drawings, in which.:

Fig. l is a vertical sectional view of a preferred form of the invention attached to the drawbar of a countersinking tool, a workpiece being shown fragmentarily, and the anchor being shown in its contracted condition just after it has been passed through the hole to be countersunk;

Fig. 2 is a similar view showing the anchor exconcentricity between the countersink bit ready to begin its cutting-operation; and

Fig. 3 is aperspective view of an expansible sleeve which constitutes a part ofthe invention.

Referring to the drawings, it will be seenY that this anchor includes an inclined surface type expander II), a longitudinally split expansible sleeve II, and a drawbar I2 seated axially in the expander and adapted to serve as the means for moving the expander axially with relation to the sleeve. It should be noted thatl the drawbar or a similar functional element actuallyr Yconstitutes an essential'part of this invention.

As to details of construction, the expander is generally cylindrical and has an enlarged head I'3, an adjacent intermediate cylindrical slideway I4` of reduced' diameter, an elongated cylindrical portion I5 ofstill smaller diameter, anda frusto-conical end It..v The expander has a central bore I] which is threaded to receive one end ofY the drawbar` I2. The head end of this ex-l pander` is counterbored to receive a hard fibre washer I8 which is locked in position by rolling the edge` ofthe counterbore shoulder inward, as atA I9". The diameter ofthe head I3 is suchas to permit it toV pass through the hole in workpiece 20. The libre washer serves as a friction lock to prevent the Adrawbar I2 from backingV out of its seat in the expander .during the repeated expansion and contraction of the anchor.

The sleeve Il is.. generally cylindrical but has anannular shoulder `2l, a slightly taperedexterior surface 22, and a truste-conical exterior end 'surface 23. It has a plurality of radially disposed longitudinal slots extending from its end 2,3` to. a` point near its opposite ends, and the major part of its Wall is-thus divided into a plurality. of sector shaped segments eachof which is inherently resilientdue tothe characteristics of themetal. of which the sleeve is made, and. can

therefore be moved radially outward from the sleeve axis. The-external diameter of this sleeve is no greater than theexternal diameter of the expander head I3.

Internally the sleeve IIv has a normally cylindrical bore- 24 ofV adiameter to slidably seat on thecy-lindrical slideway I4,- Zat its oppositeend to .slideably embrace the drawbar I2, and a connectingconical bore 26 adapted to contact and cooperate with the conical exterior surface I6 of the expander. As shown in Fig. 1, tapered at substantially the same angle when the small end of the sleeve is fully contracted.

asmaller` central bore these two surfaces IG'and 26 are Operation Fig. 1 shows the anchor after having passed through the hole in workpiece 20 from its upper side. The anchor is next moved to an eccentric position with relation to the hole so that a portion of annular shoulder 2| underlies and is in contact with a portion of the workpiece surface surrounding the hole, as indicated at 21.

Drawbar I2 is next moved slightly axially in the direction of the arrow. Since the sleeve is held by the workpiece against movement in this direction, the expander moves in a sleeve penetrating direction, and the conical expander surface I6 (Fig. 2) cams on thesleeve surface 26 and forces the individual segments of the sleeve radially outward, increasing the exterior diameter of thesleeve surface 22 until it is forced firmly against the wall of the hole in the workpiece. The degree of outward movement of each individual segment is identical because the conical surfaces I6 and 26 are concentric to the longitudinal axis of drawbar I2. Simultaneously the diameter of annular shoulder 2I is increased, as shown in Fig. 2, so that the entire surface of the shoulder is in contact with the workpiece surface surrounding the hole. A firm anchor against movement of the anchor assembly in the direction of arrow 28 is thus created.

To release the described anchor it is only necessary to move the drawbar slightly away from its contact with the workpiece. The inherent resilience in the individual segments of the sleeve force thesurface 26 to cam against the contacting surface of the expander. This camming action moves the sleeve longitudinally on slideway I4 and the entire sleeve returns to the position Yshown in Fig. l, with all segments retracted;

The entire anchor assembly may then be withdrawn from the hole in the workpiece,

It should be noted that the diameters of both expander and sleeve should be varied with the diameter of the hole in which it is desired to anchor the end of the drawbar. The cooperating inclined surfaces I6 and 26 should be smooth, and the shoulder between surface i6 and normally cylindrical surface I should preferably be gently rounded, as shown, to facilitate the camming action between the two surfaces.

While this anchor has been described in connection with a countersinking tool which has acountersink bit 29 movable axially as well as rotationally on drawbar I2, it will be apparent that it can be used on an end of any elongated element which it is desired to anchor in a drilled hole in a fixed part.

Having described the invention with sufdcient clarity to enable those familiar with this art to construct and use it, I claim: n

1. A normally contracted expansible anchor for a draw bar adapted to be passed axially through a hole in a work piece and to expand and anchor therein in response to draw bar thrust applied in a withdrawing direction, said anchor comprising: a generally cylindrical sleeve expander rigidly secured concentrically on the draw bar; an external annular shoulder near the outer end of said expander facing the direction of draw bar pull; an external frusta-conical camming surface at the inner end of the expander, also facing the direction of draw bar pull; an external cylindrical surface intermediate the ends of the expander; a generally cylindrical sleeve having its outer end slidably and concentrically seated on and encompassing the said cylindrical surface of said expander for movement axially with relation thereto; an external annular shoulder near the inner end of said sleeve facing said inner end and in the direction of draw bar pull; a plurality of circumferentially spaced longitudinally disposed slots in said sleeve extending from its inner end to a point near its outer end, dividing the slotted portion of the sleeve into a plurality of radially exible lingers, the free ends of which project in the direction of draw bar pull; and an internal frusto-conical camming surface within the sleeve near its inner end for cooperation with the similar camming surface at the inner end of the expander to force the inner ends of said fingers radially outward in response to movement of the expander with relation to the sleeve in the direction of draw bar pull.

2. The invention described in claim 1 in which the external diameter of the outer end of said sleeve is substantially equal to the external diameter of the annular shoulder at the outer end of the expander.

3. A normally contracted expansible anchor adapted to be fixed on an elongated draw 'bar and carried thereby, and capable of passing axially through a hole in a work piece with the draw bar and expanding in response to draw bar thrust in a withdrawing direction to anchor the draw bar in the work piece hole, said anchor comprising: an elongated substantially cylindrical expander fixed on the draw bar and having a frusto-conical inner end surface and an enlarged annular external shoulder near its outer end; and a normally contracted expansible sleeve having an annular outer end carried by and slidable axially along the cylindrical portion of said expander, that portion of the sleeve from its annular outer end to its inner end being divided longitudinally into a plurality of relatively narrow inherently resilient lingers, said sleeve having an exterior annular shoulder near its inner end for contacting a work piece surface when said fingers are expanded radially outward, said sleeve also having an interior conical surface near its inner end to cooperatively cam on the frusto-conical surface of said expander in response to a sleeve penetrating movement of the expander resulting from draw bar pull, the maximum outside diameter of said sleeve while its fingers are in contracted position being no greater than the diameter of the hole in which the draw bar is to be anchored.

JAMES L. HILL.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,364,489 Edelblut Jan. 4, 1921 1,721,310 Miller July 16, 1929 1,851,421 Conklin Mar. 29, 1932 2,393,587 Bugg et al. Jan. 29, 1946 2,479,660 Wright Aug. 23, 1949

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