Wallboard anchor

An anchor for wallboard installation includes an elongated anchor body including a driving end and a wall boring end. The anchor body has a main body portion running from the driving end toward the wall boring end. The wall boring end includes a plurality of axially cutting extending teeth. The anchor body includes an internal bore and diametrically opposed slots to facilitate split of an end portion of the anchor body when the anchor is installed in a wall and a fastener is inserted for mounting an object.

TECHNICAL FIELD

This application relates generally to wall anchors for drywall and other types of wallboard, and more particularly, to a wallboard penetrating anchor.

BACKGROUND

A variety of types of wall anchors are known, including anchors that can be rotated into wallboard without pre-drilling a hole in the wallboard. Improvements in both the manufacturability and performance of such anchors is continually sought.

SUMMARY

In one aspect, an anchor for wallboard installation includes an elongated anchor body including a driving end and a wall boring end. The anchor body has a main body portion running from the driving end toward the wall boring end. A wall seating flange extends radially outward from a rearward end of the main body portion, wherein the main body portion includes a thread that runs from an intermediate location along a length of the main body portion and toward the wall seating flange. The wall boring end includes a plurality of axially cutting extending teeth, wherein each cutting tooth includes a forward cutting edge and a radial cutting edge. For each cutting tooth, the radial cutting edge is defined by an intersection of a substantially planar first wall segment of the cutting tooth and a substantially planar second wall segment of the cutting tooth. The elongated anchor body includes a central axis. For each cutting tooth, the substantially planar first wall segment runs substantially parallel to but offset from the central axis, and the substantially planar second wall segment extends radially inwardly to define, in an axial end view, an enclosed acute angle. The elongated anchor body includes a distal positioning tip at the wall boring end. For each cutting tooth, the forward cutting edge extends radially outward from and rearward from the distal positioning tip and axially toward the driving end such that an angle enclosed by each forward cutting edge and the central axis is less than ninety degrees and more than sixty degrees. A pair of diametrically opposed recesses are formed in the main body portion, wherein a pair of diametrically opposed slots are provided in the anchor body, wherein each slot includes a first end that begins in one of the recesses, wherein each slot extends toward the distal positioning tip of the wall boring end.

In another aspect, an anchor for wallboard installation includes an elongated anchor body including a driving end and a wall boring end. The anchor body has a main body portion running from the driving end toward the wall boring end. The wall boring end includes a plurality of axially cutting extending teeth.

In yet another aspect, an anchor for wallboard installation includes an elongated anchor body including a driving end and a wall boring end. The anchor body has a main body portion running from the driving end toward the wall boring end. A wall seating flange extends radially outward from a rearward end of the main body portion, wherein the main body portion includes a thread that runs from an intermediate location along a length of the main body portion and toward the wall seating flange. The wall boring end includes a plurality of cutting teeth. A pair of diametrically opposed recesses are formed in the main body portion, wherein a pair of diametrically opposed slots are provided in the anchor body, wherein each slot includes a first end that begins in one of the recesses, wherein each slot extends toward a distal tip of the wall boring end. The anchor body includes an internal bore running from the driving end toward a distal tip of the wall boring end, wherein the internal bore terminates short of the distal tip. Each slot is a through slot to the internal bore, wherein each slot runs from the first end for an axial length and terminates short of the distal positioning tip, wherein each recess has a curved perimeter shape for stress relief. The internal bore includes a first bore section running from the driving end toward the distal tip and a second bore section running from the first bore section toward the distal tip. The second bore section has a smaller size in axial end view than the first bore section, such that a fastener threaded into the bore causes and end section of the anchor body to split when the fastener pushes radially outwardly on inner wall portions of the second bore section.

DETAILED DESCRIPTION

In the drawings and description of various anchor embodiments below, the term wallboard is generally used to refer to the most common wallboard such as drywall, but it is recognized that the anchor components could be suitable for any other friable wallboard material, such as dense corks or foams or other materials that can crumble. Accordingly, the term wallboard as used herein is intended to broadly encompass, for example, both typical drywall (aka plasterboard and gypsum board) and such other friable wallboard materials.

Referring toFIGS.1-14, in one embodiment, an anchor10includes an elongated anchor body12with a lengthwise axis13, and has a rearward driving end14and a forward or distal wall boring end16. The anchor body may, for example, be formed of a molded plastic material. The driving end14of the body12includes a substantially cylindrical main body portion20with a high thread22formed thereon. The high thread22will operate to engage with wallboard material to help retain the anchor body to a wall when installed. The high thread runs helically with a constant pitch and may have an axial length L22that is between about 25% and about 45% of the full anchor length L10. The diameter of the main body portion20may, for example, be between about 0.25 inches and about 0.35 inches. A major portion of the thread along an axial length L22M includes a substantially constant thread height and a minor portion of the thread along an axial length L22mhas a thread height that continuously reduces. The length L22M may be more than 1.5 times the length L22m.

A flange24extends outward from the front rear end of main body portion20and will engage with the front surface of a wall to define the limit of penetration of the anchor. The underside of the flange24may be slightly tapered (e.g., slight frusto-conical shape) in order to push the outer surface of the wall inward slightly so that the face of the flange sits more flushly with the wall surface. The thread22begins at an axial location26along the body portion20and ends at a location28short of the flange24. The end face of flange24defines an opening30into the cylindrical body20and includes an end portion defining a fastener driving recess32(e.g., a Phillips recess or some other configuration). Inward of the recess32an internal bore34of the cylindrical body20is provided for receiving a threaded fastener (e.g., a nut or bolt). An axial length L20of the cylindrical body20may be between about 55% and about 75% of the anchor axial length L20(such as between about 60% and about 70%).

It is recognized that the main body portion20need be completely cylindrical along its full length. For example, the portion of main body portion20toward the wall boring end, or the full length of the main body portion20, could include a small taper to reduce in diameter toward the wall boring end. Alternatively, there could be a slight step down in the diameter of the main body portion20toward the wall boring end (e.g., in the vicinity of the recesses40described below). Whether the body is completely cylindrical, partially cylindrical, fully or partially tapered, or included a slight step down in diameter, the term substantially cylindrical as used herein is considered to be applicable to the main body portion so long as a diameter of the main body portion at its forward end (toward the wall boring end of the anchor) is no less than eighty percent of a diameter of the main body portion at its rear end (proximate the flange24).

Diametrically opposed recessed sections40are provided on the outer surface of the main body portion20in order to provide wall portions44of reduced thickness, and thus reduced strength. The perimeter of each recess40is curved for stress relief and may include small ear projection sections42on sides of the recess and facing toward the driving end of the anchor body. Diametrically opposed slots50are provided, each of which includes one end52that begins in the wall portion44of the recess40. The slots extend toward the wall boring end14. The slots extend completely through the main body portion20and into the internal bore34with a larger bore section34A and a smaller bore section54in the wall boring end16of the anchor. The bore section54terminates in an end wall portion56, but the slot continues as a recessed groove58onto a positioning tip60of the wall boring end16. Here, the positioning tip60has substantially conical configuration. The recessed grooves58provide a zone of weakening to facilitate breakage of the positioning tip60during anchor split as is described further below.

Between the positioning tip60and the main body portion a set of radially spaced apart and axially extending wallboard cutting teeth70are provided. In the illustrated embodiment, three teeth70are provided, but the number could vary. The anchor is configured to be driven into a wall by rotation in a clockwise direction as viewed axially from the driving end of the anchor. Each cutting tooth therefore includes a forward cutting edge72and a radial cutting edge74. The forward cutting edge72extends radially outward and slightly rearward (i.e., away from the positioning tip60and axially toward the driving end14). By way of example, an angle θ enclosed by each forward cutting edge72and the anchor axis13may be between about seventy degrees and about eighty-two degrees (such as between seventy-three degrees and seventy-nine degrees). The radial cutting edges74run substantially parallel to the anchor axis13. The cutting edges74lie in a common circular cylinder shape or profile (not shown) that is centered on the anchor axis13. The cutting edges74lie slightly radially inward of the outer surface of the main body portion20. Each radial cutting edge74is defined by the intersection of a substantially planar wall segment76and a substantially planar wall segment78. Each wall segment76may run substantially parallel to but offset from the central axis13of the anchor, and each wall segment78may extend radially inwardly, running in the direction away from its adjacent wall segment76, to define, in an axial end view, an enclosed acute angle α. Angle α may, for example, be between about fifty degrees and about seventy degrees (such as between about fifty-five degrees and about sixty-five degrees).

FIGS.9-14depict an anchor install sequence, inclusive of fastener attachment to the anchor. The anchor10is initially placed with its positioning tip against the wall100, perFIG.9, and an axial force102is applied. The axial force moves the tip into the wall sufficiently to bring the forward cutting edges of the cutting teeth adjacent the wall, perFIG.10. Rotational torque104is applied, along with continued axial force102, to rotate the anchor entirely through the wall to achieve a set install position with flange24seated relatively flushly into the wall surface perFIG.11. Notably, the cutting teeth70cut a primary bore into the wall, with the bore slightly smaller in diameter than the main body portion20, but large enough to allow user forces to move the main body portion20into the bore. Continued application of rotational and axial force engages the thread22into the wall, with the thread22cutting a thread path into the wall. In this position, the high thread22engages with the wallboard material and provides relatively solid retention against axial pull-out.

An object110can be mounted to the anchor and wall using a threaded fastener112perFIG.12, where the fastener passes through a hole in the object110and then into the internal bore(s) of the anchor10. The fastener threadedly engages with internal walls of the larger size bore34(seeFIG.5B). The fastener may be sized so that when the fastener reaches the smaller size bore54(seeFIG.5B), the force of the fastener against the lateral walls of the bore54causes an end segment of the anchor to split along the diametrically opposed slots50(e.g., before the distal end of the fastener reaches the end56of the bore54). This split causes the portions of the anchor internal of the wall (e.g., from recesses to the positioning tip) to expand outwardly perFIG.14, providing additional retention against wall pull out. Notably, inFIGS.13and14here, the object being hung is not shown. Typically, the fastener112will be long enough to cause anchor split before the fastener head tightly engages the object110and presses it against the wall.

It is to be clearly understood that the above description is intended by way of illustration and example only, is not intended to be taken by way of limitation, and that other changes and modifications are possible. Other configurations are also possible.