US3385156A - Self-drilling anchor bolt assembly - Google Patents

Description

y 8, 1968 c. D. POLOS 3,385,156

SELF-DRILLING ANCHOR BOLT ASSEMBLY Filed March 30, 1966 2 Sheets-Sheet l WWII" May 28, 1968 c. D. POLOS 3,385,156

SELF-DRILLING ANCHOR BOLT ASSEMBLY Filed March 30, 1966 2 Sheets-Sheet? 6 4/ 43 YIIIIIII I-- III/M 44 INVENTOR CdvzaZmzizkeefl oa )zyW, 4

A T TORNEYS United States Patent 3,385,156 SELF-DRILLING ANCHOR BOLT ASSEMBLY Constantine D. Polos, Park Ridge, 111., assignor to Dan Polos Industries, Inc, Addison, 111., a corporation of Illinois Filed Mar. 30, 1966, Ser. No. 538,778 6 Claims. (C1. 85-68) ABSTRACT OF THE DISCLOSURE A self-drilling anchor bolt assembly provided with integral rotary means for drilling the hole in which the assembly is placed for use.

This invention relates to bolt anchors used to attach bolts to walls, floors, and the like, and, more particularly, it relates to anchors of the type having an intermediate collapsible section which expands transversely into contact with the inner surface of a wall in which the anchor is installed.

Anchor bolts of the general type with which this invention is concerned have long been known to the art. An anchor bolt of this type comprises an elongated hollow body having an intermediate portion which collapses longitudinally and expands outwardly to engage the inner surface of a wall, when the associated bolt is rotated to bring about collapse of the sleeve. In use, such anchors require the drilling of a hole of suitable size in the wall, into which the anchor is placed. A disadvantage of this type of anchor is the fact that a drill must be available for making the hole into which the anchor is placed. Since the size of the hole must be correlated with the size of the anchor, it is required that the user of such anchors have available a supply of dillerent sized drill bits for use whenever an anchor is to be installed.

Several attempts to eliminate the necessity for having and using a separate drill have been made, as evidenced by prior patents describing anchors provided with means for forming their own holes. In general, these means comprise sharpened points on the ends of the anchors which permit the anchors to be driven in the manner of nails. Although such constructions may be suitable in small sizes and when used in relatively soft materials, they cannot be used effectively in the larger sizes nor can they be used with hard wall surfaces, such as those made of plywood.

The anchor of the present invention obviates the necessity for use of a separate drill by being provided on its end with a cutting head that cuts a hole through the wall of a size commensurate with the size of the anchor itself, being thereby much more convenient in use. In another aspect, the invention is provided with means which indicates when the intermediate collapsible portion of the sleeve has been sufliciently collapsed to make secure contact with the inner surface of the wall and which further improves the gripping action against such surface.

The invention will be better understood from the following detailed description thereof, taken in conjunction with the accompanying drawings, in which:

FIGURE 1 is a side view of a typical anchor bolt assembly of the invention in its normal or uncollapsed condition;

FIGURE 2 is a view of the assembly of FIGURE 1 after it has been installed, showing the gripping action against the wall of lugs attached to the collapsed middle portion of the sleeve;

FIGURE 3 is a right-hand view of the assembly of FIGURE 1 showing the cutting head and the staggered wall retaining tangs in the head flange;

FIGURE 4 is a cross-sectional view through the cutting head, along the line 4-4 of FIGURE 2;

FIGURE 5 is a fragmentary view in partial section of another embodiment of the invention showing a different type cutting head and of the means of securing threaded engagement between the bolt and the sleeve;

FIGURE 6 is a cross-sectional view along the line 66 of FIGURE 5 showing the inwardly projecting ears used to engage the threads of the bolt;

FIGURE 7 is a view of another embodiment having a cutting head similar to that of FIGURE 5 in which a ditferent means for forming the threaded engagement between the cutting head and the bolt is used;

FIGURE 8 is a cross-sectional view along the line 88 of FIGURE 7;

FIGURE 9 is a left-side view of the bolt of FIG- URES l and 2 showing the socket means for rotation of the bolt;

FIGURE 10 is a side view of the bolt head of FIG- URE 9 in partial section showing the socket used for rotating the bolt; and

FIGURE 11 is a fragmentary view of a cutter head similar to that shown in FIGURES l and 2 in which the lugs for threaded engagement with the bolt are formed by triangular coupons punched in the wall of the sleeve.

Referring to FIGURES l and 2, the anchor assembly of the invention consists of two separable pieces which are threadedly engaged. The first of these, bolt 10, is received within the second, an elongated, generally tubular body portion 11 which in turn consists of a sleeve 12 and a cutting bead 13 interconnected by a plurality of connecting strips 14. The end of the body 11 away from the cutting head is provided with a head flange 16 equipped with a plurality of tangs 17 which engage the wall 15 in which the anchor is used in order to prevent rotation of the anchor. Bolt 10, which is received by body portion 11, is provided with a threaded shank 18 terminating in a sharpened point 19 which acts as a pilot for cutting head 13 when the anchor is used. Although square threads are shown in the embodiment of FIGURES 1 and 2, any other thread shape could also be used, as will be apparent to those skilled in the art. Cutting head 13 is internally threaded to match the threads on shank 18 by means of which longitudinal movement of cutting head 13 toward bolt head 20 can be obtained on rotation of the bolt.

In the embodiment of the cutting head shown in FIG- URES 13, cutting head 13 is provided with cutting lips 21 which function in a manner similar to that of a conventional twist drill on rotation of the body portion 11. In the uncollapsed form of the anchor assembly, shown in FIGURE 1, the sharpened point 19 of bolt 10 extends sufficiently beyond the end of cutting head 13 to act as a pilot for the hole to be drilled.

Interconnecting strips 14 are weakened at predetermined points intermediate their ends, at which weakened points the strip will bend outwardly, i.e., transversely of the anchor axis, when a compressive force is applied to the ends thereof. In the embodiment shown in FIG- URES 1 and 2, the weakened point is established at 22 by a decrease in the width of the strip at this point and by the inclusion of a die groove 24 which insures that the strip will bend at the desired point, thereby dividing the length of the strip into two unequal portions, a shorter portion 23 connected to sleeve 12 and a longer portion 25 connected to cutting head 13.

In a preferred embodiment of the invention, as shown in FIGURES 1 and 2, strips 14 are provided with lugs 26 at the weakened point 22. Lugs 26 are generally triangular in shape and are inwardly depressed in the uncollapsed form of the anchor shown in FIGURE 1.

When connecting strips 14 are collapsed, by movement of cutting head 13 toward sleeve 12, as shown in FIGURE 2, lugs 26 assume a position generally perpendicular to the inner surface of wall 15. This collapsing movement is brought about by rotation of bolt 10 while holding body portion 11 stationary. As strips 14 collapse, lugs 26 ap proach and are eventually embedded into the wall. Lugs 26 thereby serve two functions: firstly, the increase in resistance by turning of bolt 10, which is felt when the lugs 25 contact wall 15, serves as an indication that collapse of strips 14 has progressed far enough and thereby avoids overtightening which may result in loosening of the anchor within the wall with conventional constructions of the type heretofore known; secondly, the engagement of lugs 26 with wall 15 aids in preventing undesired rotation of body portion 11 when bolt 10 is rotated to be removed and replaced in the installed anchor.

As a further protection against rotation of the body portion 11 while strips 14 are being collapsed in order to fix the anchor, head flange 16 is provided with a plurality of inwardly directed tangs 17, as shown particularly in FIGURE 3. In order to increase the holding power of the tangs, the faces thereof are inclined radially at different angles, e.g., a and ,8, as shown, thus positioning the pointed ends thereof at different distances from the longitudinal axis of body portion 11. In this manner, the resistance to rotation is considerably enhanced over that which would have been obtained had the points all fallen at the same distance from the axis.

The cutting head shown in FIGURES 1 and 2 is obtained by pinching the end of body portion 11 to obtain two laterally extending protuberances or ears 31 diagonally disposed on the end of body portion 11, as shown in FIGURE 4. Each of cars 31 is ground in a plane oblique to the axis of body portion 11 to obtain a cutting lip 21 of the conventional type found on a twist drill. It should be observed that cars 31 must be wide enough so that the hole drilled by rotation of the anchor assembly has sufi'icient diameter to clear both sleeve 12 and the interconnecting strips 14 which are advisably outwardly slightly bowed in the uncollapsed form of the device in order to insure that the strips collapse outwardly as desired when collapsing force is applied.

The embodiment shown in FIGURES 1-3 is internally threaded within cutting head 13 by means of a conventional tapping operation. Alternative methods of obtaining threaded engagement between the bolt and the cutting head are shown in FIGURES 5 and 7. In both of these embodiments, inwardly directed ears 41 (FIGURES 5 and 6) and 51 (FIGURES 7 and 8) are obtained by shearing coupons of metal from the tubular wall portion of the cutting heads. In FIGURES 5 and 6, the inwardly directed coupons are sheared on two opposing sides and bent on the remaining two sides so as to produce inwardly extending ears 41 which are positioned to engage the threads of bolt 42. In FIGURES 7 and 8, ears 51 are produced by shearing a coupon on three sides and bending it on the remaining side, again to produce inwardly directed projections which engage the threads of bolt 52.

Still another form of threaded engagement which can be used in the cutting head is depicted in FIGURE 11 which shows a two-bladed cutting head 61 similar to that shown in FIGURES l and 2 provided with a plurality of triangular partially cut-out coupons 62 which extend radially inwardly to engage the triangular threads of a bolt intended to be used therewith.

The cutting heads shown in FIGURES 5 and 7 are of a type which differs from that of FIGURES 1 and 2 and represents an alternative construction. The heads 43 and 53 contain saw teeth 44 and 54, such as those conventionally found in a circular saw, which may be alternately staggered to provide clearance for the chips which are formed. In any event, however, the hole which is drilled must have sufiicient diameter to clear the widest portion of the anchor which is inserted therein,

The embodiment of FIGURE 7 also illustrates an alternative form of construction for connecting strips 54 which are not provided with wall-engaging lugs as are those illustrated in FIGURES 1 and 2. In addition, strips 54 are stiffened at their bending points 55 by being crowned instead of having a die groove.

In order to drill the initial hole with the anchor of the invention, the bolt, e.g., 10, is first screwed as far as it will go into firm engagement with head flange 16 (FIGURE 1). At this point, further rotation of the bolt will cause rotation of the cutting head 13. The pilot point 19 is placed in a desired location on the wall, and the entire assembly is rotated, preferably with a power drill but alternatively by a hand drill, thereby causing the cutting head 13 to drill a hole into the wall. In order to avoid drilling too far and thereby causing tangs 17 to score the outer surface of the wall 15, sleeve 12 is provided with an easily visible circumferential band and dot 27 of a suitable contrasting color which, when seen to be flush with the outer surface of the wall, indicates imminent engagement of the tangs with the wall surface and serves as an indication that further drilling should be stopped.

FIGURES 9 and 10 show the details of a desirable configuration of the bolt head 20 (FIGURE 1) for use in the invention. The head 20 is provided with a socket 28, suitably hexagonal, as well as a transverse slot 29, which permits either the use of a mating hexagonal wrench or a conventional or special screw driver (i.e., one equipped, if desired, with a central positioning lug) for use in drilling the hole in the wall in which the anchor is to be used and for rotating the bolt to cause the anchor to collapse into firm engagement therewith.

After a hole has been drilled in the wall, as described above, head fiange 16 is then driven into the wall by means of suitable pressure, thereby immobolizing body portion 11. By then rotating bolt 10, cutting head 13 will be drawn toward the wall 15 causing collapse of the connecting strips 14 in the manner previously described.

It will be seen that the construction of the invention eliminates the necessity for a separate drill for use with the anchor, which drill may be unavailable when use of the anchor is desired. The locking lugs, which are provided intermediate the ends of the collapsible strip, further contribute to the effectiveness of the device by preventing inadvertent overtightening as well as providing for secure engagement of the anchor with the inner surface of the wall on which it is used.

The foregoing detailed description has been given for clearness of understanding only, and no unnecessary limitations should be understood therefrom, as modifications will be obvious to those skilled in the art.

What is claimed is: I

1. A self-drilling bolt anchor assembly comprising:

a bolt having a threaded shank, an enlarged head on one end of the shank provided with means for rotating said shank, and a sharpened point on the other end thereof;

a sleeve encircling said bolt adapted to project through an opening in a wall;

an annular flange attached to the outer end of said sleeve;

tang means carried by said flange for preventing rotation of said sleeve when said flange is in contact with said Wall;

an internally threaded rotary cutting head removably engaging said shank and spaced from said sleeve, said head including cutting means;

a plurality of deformable connecting strips interconnecting said cutting head and said sleeve, each said connecting strip being weakened at a predetermined point so that it will collapse and bulge outwardly when a longitudinal compressive force is applied to the ends thereof, said weakened point being spaced so as to divide said connecting strip into a shorter sleeve portion and a longer head portion.

2. The assembly of claim 1 in which said interconnectin strips are provided with lugs at said weakened points which, on collapse of said intermediate strips, engage said wall and serve to inhibit rotation of said anchor.

3. The anchor of claim 1 in which said cutting means comprises a pair of diagonally opposed laterally extending pinched protuberances formed from the wall of said cutting head, each protuberance being provided On its forward end with a cutting edge.

4. The anchor of claim 1 in which said cutting head means comprises a plurality of saw teeth circumferentially arranged on said cutting head.

5. The anchor of claim 1 in which the threaded engagement between said cutting head and said threaded bolt is obtained by means of inwardly directed coupons partially cut from the wall of said cutting head.

6. The anchor of claim 1 in which said tang means comprises a plurality of generally triangular tangs partially cut from said rim and inwardly bent, the faces of said tangs being inclined radially at difierent angles, whereby said tan-gs are positioned at different radial distances from the axis of said sleeve.

References Cited UNITED STATES PATENTS 422,307 2/1890 Libbey 8545 1,996,121 4/ 1935 Phillips 85-68 2,018,251 10/1935 Croessant 8571 2,707,012 4/1955 Cox 151--35 2,913,953 11/1959 Tendler 8571 FOREIGN PATENTS 408,668 4/ 1934 Great Britain.

EDWARD C. ALLEN, Primary Examiner.

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