Patent Description:
The present disclosure relates generally to threaded fasteners that are drivable into a substrate, and more particularly to improved one piece threaded anchors.

Threaded fasteners such as anchors are well known and commercially used throughout the world for securing objects to a variety of substrates. A variety of threaded fasteners can be used to secure objects to concrete, masonry, and other cementitious substrates. Typically, such threaded fasteners include a head, a shank, and a thread formation on the shank for frictionally engaging the substrate into which the fastener is driven. The head typically includes a mechanical engaging structure for engagement by a tool that is used to rotate the threaded fastener and drive the threaded fastener into the substrate.

Often such threaded fasteners are optimally used by pre-drilling the concrete, masonry, or other substrate, for example with a hammer drill equipped with a masonry drill bit. Once the substrate has been pre-drilled, and a correctly sized cavity formed therein, an appropriately sized threaded fastener may be driven or screwed into the substrate to secure an object thereto. One example of such a threaded fastener is described in <CIT> entitled "Threaded Concrete Anchor" and assigned to Illinois Tool Works, Inc. in Glenview, Illinois (who is also the assignee of this patent application). Such fasteners are commercially distributed under the Tapcon® mark, and are sometimes referred to as Tapcon screws or anchors. Tapcon is a registered trademark of Illinois Tool Works, Inc. Prior patent document <CIT> describes an example of a fastening bolt which includes a shaft, a head, a drilling portion, and first threads alternating with second threads. Some threads near the drilling portion form respective cutting grooves and recesses thereon. Prior patent document <CIT> describes a masonry anchor including a head and a body integral to the head and extending therefrom.

Often such threaded fasteners are driven into such a substrate using a powered tool, such as an electric or pneumatic power driving tool or impact driver that imparts a rotational force or torque on the threaded fastener. For example, an impact driver may be fitted with an appropriate bit or socket for engaging the complimentary mechanical engaging structure of the head of the threaded fastener, to rotate the threaded fastener in a tightening direction such that the threads of the threaded fastener engage the substrate. When the threaded fastener is rotated in a tightening direction, the threads of the threaded fastener grip the inside surfaces of the substrate that define the cavity (e.g., the surfaces that define the pre-drilled hole in the substrate), causing the threaded fastener to be driven deeper into the substrate until the head of the threaded fastener comes into contact with either the object being attached by the threaded fastener to the substrate (such as a bracket, flange, clip, or other mechanical device having a hole in it through which the fastener passes). This contact thereby prevents the threaded fastener from being driven, rotated, or tightened further. This results in the threaded fastener being fully tightened and the object being affixed to, secured to, or compressed into contact with the substrate.

Certain problems have arisen due to improvements in electric and pneumatic power driving tools that have caused such tools to become capable of delivering relatively higher levels of torque. When such driving tools are used to drive certain known threaded fasteners, such as those described above, the threaded fasteners can be subjected to relatively large amounts of torque from the rotational forces imparted by these power driving tools. For example, as the threads of the threaded fastener engage the substrate, the threaded fastener experiences frictional resistance forces which tend to impede further driving of the threaded fastener into the substrate. At the same time, the power driving tool is imparting a rotational force or torque on the threaded fastener (typically via the head of the threaded fastener) in an effort to rotate the threaded fastener in a tightening direction and drive it into the substrate. These opposing forces impart significant torsional stresses on the threaded fastener, placing the shank of the threaded fastener under shearing torsional stresses.

These torsional stresses can be so great in various circumstances as to cause the threaded fastener to fail due to the opposing forces or torques placed on the threaded fastener. Over tightening of such threaded fasteners during the driving process is a primary cause of such overstressing of the shank of the threaded fastener, and can result in failure of the threaded fastener due to excessive torsional forces. Threaded fasteners that are subjected to over tightening often fail along the shank, including an upper portion of the shank adjacent to the head of the threaded fastener. Other failures occur at the top of the shank, just under the head of the threaded fastener.

Accordingly, there is a need to provide threaded fasteners that solve these and other problems.

Various embodiments of the present disclosure provide an improved threaded fastener drivable into a substrate that solves the above problems. For brevity, the threaded fastener of the present disclosure may sometimes be referred to herein as the fastener or the anchor (or threaded anchor).

In various embodiments of the present disclosure, the fastener or anchor includes : (i) a head; (ii) a shank connected to the head at a first end and forming or having a tip at a second end; and (iii) a first helical thread formation extending outwardly or transversely from the shank. The shank has a first portion proximate the head, a second portion adjacent to the tip, and a third portion between the first and second portions. The shank has a longitudinal axis extending from the head to the tip. The first portion has a substantially constant outer diameter along a length of the shank. The second portion has a substantially constant outer diameter along the length of the shank. The third portion has an outer diameter that decreases along the length of the shank in a direction along the longitudinal axis from the head to the tip. The first helical thread formation has a thread form formed from two portions disposed upon opposite lateral sides of the thread form. The thread form has a root positioned along the second and third portions of the shank. The outer diameter of the first helical thread formation on the third portion of the shank increases along the length of the shank in a direction along the longitudinal axis from the head to the tip.

In various embodiments of the present disclosure, an outer surface of the third portion of the shank forms an angle α with the longitudinal axis, and the outer diameter of the first helical thread formation on the third portion of the shank forms an angle β with the longitudinal axis.

In other various embodiments of the present disclosure, the fastener includes: (i) a head; (ii) a shank connected to the head at a first end and forming or having a tip at second end; and (iii) a first helical thread formation extending outwardly or transversely from the shank. The shank has a first portion proximate the head, a second portion proximate the tip, and a third portion between the first and second portions. The first helical thread formation extends from the shank and has a thread formed from two portions disposed upon opposite lateral sides of the thread form. The thread form has a root positioned along the second and third portions of the shank. The head includes a top portion distal from the shank, and a bottom portion adjacent to the shank. The top portion of the head defines a, mechanical engaging structure engageable by a tool. The bottom portion of the head includes a bottom surface and a plurality of ribs arranged radially around an axis of the head. The ribs extend outward from the bottom surface in a direction towards the tip. The ribs are shaped to frictionally engage a face of an object being attached to a substrate into which the fastener is driven as ribs and the bottom surface approaches and ribs comes into contact with object being attached to the substrate.

In various embodiments of the present disclosure, each of the plurality of ribs of the bottom portion of the head includes a leading face and a trailing face, wherein the leading face is configured to engage a surface of the object being attached to the substrate as the fastener is driven through the object and into the substrate.

In various embodiments of the present disclosure, the leading face forms an angle θ with the bottom surface, wherein θ is less than <NUM> degrees and greater than <NUM> degrees.

In various embodiments of the present disclosure, the one or more of the thread formations or threads of the threaded fastener are formed with one or more grooves that are each partially defined by a straight cutting edge in the thread formation or thread. The straight cutting edge assists the thread formation or thread in cutting into the substrate (such as a concrete substrate). This enables the threaded fastener to form its path more efficiently, reduces necessary installation torque, and reduces the likelihood of breakage of the threaded fastener during installation or use.

Other objects, features, and advantages of the present disclosure will be apparent from the following detailed disclosure, taken in conjunction with the accompanying sheets of drawings, wherein like reference numerals refer to like parts.

Referring now to the Figures, a threaded fastener <NUM> of one example embodiment of the present disclosure is generally shown in <FIG>, <FIG>, <FIG>, and <FIG>. The fastener <NUM> is configured for use in fastening such as anchoring in substrates, and in particular for securing or anchoring objects or portions of objects to concrete, masonry, or other substrates as described herein. The fastener <NUM> includes a head <NUM>, a shank <NUM>, and thread formations <NUM> and <NUM> extending outwardly from the shank <NUM>. The shank <NUM> has a length L1 and is integrally connected to the head <NUM> at a first end <NUM> of the shank <NUM>. Generally opposite the first end <NUM> of the shank <NUM> is a second end <NUM> of the shank <NUM> which forms a tip <NUM>. The tip <NUM> is pointed to aid in penetrating the substrate in which the fastener <NUM> is being driven, as described herein.

The shank <NUM> includes a first portion <NUM> adjacent to the head <NUM>, a second portion <NUM> adjacent to the tip <NUM>, and a third portion <NUM> generally between the first portion <NUM> and the second portion <NUM>. The shank <NUM> has a longitudinal axis A1 extending along the length L1 of the shank <NUM>, generally from the head <NUM> to the tip <NUM>. The first portion <NUM> of the shank <NUM> extends from the head <NUM> to the third portion <NUM>, and has a substantially constant outer diameter D1 along the length L1 of the first portion <NUM> of the shank <NUM>. Thus, the outer diameter of the end of the first portion <NUM> abutting the head <NUM> is substantially the same as the outer diameter of the opposite end of the first portion <NUM> abutting the third portion <NUM>.

The second portion <NUM> of the shank <NUM> extends from the third portion <NUM> on one end, to the tip <NUM> of the shank <NUM> on the other end, and has a substantially constant outer diameter D2 along the length of the second portion <NUM> of the shank <NUM> (excluding the tip <NUM>). Thus, the outer diameter of the end of the second portion <NUM> abutting the third portion <NUM> is substantially the same as the outer diameter of the opposite end of the second portion <NUM> abutting the tip <NUM>.

The third portion <NUM> of the shank <NUM> is generally positioned between the first portion <NUM> and the second portion <NUM>, and serves as a transition area <NUM> of the shank <NUM>. The outer diameter D3 of a first end <NUM> of the third portion <NUM> of the shank <NUM> is substantially equal to the outer diameter D1 of the first portion <NUM> of the shank <NUM>. The outer diameter D4 of a second end <NUM> of the third portion <NUM> of the shank <NUM> is substantially equal to the outer diameter D2 of the second portion <NUM> of the shank <NUM>. In this illustrated example embodiment, the outer diameter D2 of the second portion <NUM> is less than the outer diameter D1 of the first portion <NUM>. Thus, the transition area <NUM> of the third portion <NUM> serves to enable the shank <NUM> to taper from the outer diameter D3 at the first end <NUM> to the outer diameter D4 at the second end <NUM> of the third portion <NUM>. In this way, the outer diameter from D3 to D4 of the third portion <NUM> decreases along the length L1 of the shank <NUM> in a direction along the longitudinal axis A1 moving from the head <NUM> to the tip <NUM>. Thus, the outer diameters D3 to D4 of the third portion <NUM> of the shank <NUM> taper radially inwardly along a length L1 of the shank <NUM> in the direction from the head <NUM> towards the tip <NUM>. In this illustrated embodiment, the rate of the taper is constant; however it should be appreciated that the rate of the taper may vary in accordance with the present disclosure.

As shown in <FIG>, <FIG>, <FIG> and <FIG>, the fastener <NUM> of this example embodiment of the previous disclosure further includes a first or primary helical thread formation <NUM> along or extending outwardly or transversely from a portion of the shank <NUM>. In this illustrated example embodiment, the first helical thread formation <NUM> spans substantially all of the second and third portions <NUM> and <NUM> of the shank <NUM>. The first helical thread formation <NUM> includes a thread <NUM> extruding from a fastener root <NUM>. The root <NUM> spans substantially all of the second and third portions <NUM> and <NUM> of the shank <NUM>, between the tip <NUM> and the first portion <NUM> of the shank <NUM>. The first helical thread formation <NUM> traverses the root <NUM> in a helical or spiral formation along a surface of the root <NUM> in the direction of the longitudinal axis A1.

The first helical thread formation <NUM> has an outer diameter D5, as shown in <FIG>. The outer diameter D5 of the first helical thread formation <NUM> is substantially constant along the length of the second portion <NUM> of the shank <NUM>. However, in various embodiments of the present disclosure, the outer diameter of the first helical thread formation <NUM> is tapered on the third portion <NUM> of the shank <NUM>. For example, as shown in <FIG>, the outer diameter of the first helical thread formation <NUM> may decrease from a first end <NUM> of the third portion <NUM> to a second end <NUM> of the third portion <NUM> in a direction along the longitudinal axis A1 of the shank <NUM> from the tip <NUM> to the head <NUM> or part thereof. Thus, the outer diameter D5 of the first helical thread formation <NUM> at the first end <NUM> of the third portion <NUM> in this illustrated embodiment is larger than the outer diameter D6 of the first helical thread formation <NUM> adjacent to the second end <NUM> of the third portion <NUM>. In this way, the outer diameters D6 and D5 of the first helical thread formation <NUM> on the third portion <NUM> of the shank <NUM> increase along the length L1 of the shank <NUM> in a direction along the longitudinal axis A1 from the head <NUM> to the tip <NUM>. Thus, the outer diameters D6 and D5 of the first helical thread formation <NUM> on the third portion <NUM> of the shank <NUM> taper radially outwardly along a length L1 of the shank <NUM> in the direction from the head <NUM> towards the tip <NUM>.

The illustrated example threaded fastener <NUM> also includes a second or secondary helical thread formation <NUM>. Similar to the first helical thread formation <NUM>, the second helical thread formation <NUM> includes a thread <NUM> extruding from the fastener root <NUM>. The second helical thread formation <NUM> traverses the root <NUM> in a helical or spiral formation along a surface of the root <NUM> in the direction of the longitudinal axis A1.

In this illustrated example embodiment, the thread <NUM> of the second helical thread formation <NUM> is positioned between the thread <NUM> of the first helical thread formation <NUM>. As shown in <FIG>, the second helical thread formation <NUM> is or runs generally parallel to the first helical thread formation <NUM>, with the threads <NUM> and <NUM> of each of the thread formations <NUM> and <NUM>, respectively generally radially positioned on opposite sides of the root <NUM> along the length L1 of the shank <NUM>. In various embodiments, both threads <NUM> and <NUM> are generally parallel and forming approximately the same angle with the axis A1. However, in alternative embodiments of the present disclosure, the threads <NUM> and <NUM> may be configured with differing angles to the axis A1, or differing thread pitches.

It should be appreciated that the formation and configuration of the threads <NUM> and <NUM> of the respective first and second helical thread formations <NUM> and <NUM> may take on a variety of different forms in accordance with the present disclosure. In one embodiment, the threads <NUM> and <NUM> are formed in a manner to maximize grip strength of the fastener <NUM> for use in concrete, masonry, and other cementitious substrates. One example of threads which may be appropriate for certain applications of the threads <NUM> and <NUM> of the present disclosure are described in <CIT> entitled "Threaded Concrete Anchor" and assigned to Illinois Tool Works, Inc. in Glenview, Illinois.

In the example embodiment shown in <FIG>, <FIG> <FIG>, and <FIG>, the outer diameter D7 of the second helical thread formation <NUM> is substantially constant along the length L1 of the shank <NUM> along the longitudinal axis A1. In other embodiments, the outer diameter of the second helical thread formation <NUM> tapers similar to the tapering of the first helical thread formation <NUM> described herein. The second helical thread formation <NUM> may also be configured to taper on the third portion <NUM> of the shank <NUM>, or on any other appropriate portions <NUM> and <NUM> of the shank <NUM>. In an alternative embodiment, shown in <FIG>, the second helical thread formation <NUM> includes a plurality of threads 132a and 132b that are positioned between the threads <NUM> of the first helical thread formation <NUM>. In various embodiments, the first and second helical thread formations <NUM> and <NUM> include any suitable appropriate number of helical threads <NUM> and <NUM>, which may be the same, similar, or differing in size, orientation, pitch, or configuration.

The tapering of the shank <NUM> and the first helical thread formation <NUM> on the third portion <NUM> of the shank <NUM> is depicted in greater detail in <FIG>. The tapering occurs across the transition area <NUM> of the third portion <NUM>. As explained herein, the diameter of the shank <NUM> of the third portion <NUM> uniformly decreases from a first outer diameter D3 to a second outer diameter D4 (see <FIG>) to form a tapering of the shank <NUM>, where the outer diameters D3 and D4 are the measurements from the outer surface <NUM> of the shank <NUM> to the radially opposite outer surface <NUM> of the shank <NUM>. This tapering causes the outer surface <NUM> of the third portion <NUM> of the shank <NUM> to form an angle α between the outer surface <NUM> and the longitudinal axis A1, as shown in <FIG>. The preferred angle α is varied with diameter D1, the larger of D1 is, the larger α. In a preferred embodiment, for <NUM> ( ¼ inch) or smaller diameter anchors, angle α is approximately <NUM> degrees, and is preferably between <NUM> and <NUM> degrees. For larger size anchors, the angle is not as important as smaller size anchors, and the angle α could be as large as <NUM> degree.

Similarly, the tapering of the first helical thread formation <NUM> occurs across the transition area <NUM> of the third portion <NUM>. As explained herein, the outer diameter of the first helical thread formation <NUM> increases from a first outer diameter D6 to a second outer diameter D5, where the outer diameters are measured from a straight line T1 contacting one side of the outer edges <NUM> of the threads <NUM> of the first helical thread formation to a second straight line T2 contacting the other side of the outer edges <NUM> of the threads <NUM> of the first helical thread formation <NUM>, diametrically across the longitudinal axis A1, as shown in <FIG>. The tapering of the first helical thread formation <NUM> causes the outer diameters D6 and D5 to form an angle β with the longitudinal axis A1 (between line T1 and axis A1 and between line T2 and axis A1). In a preferred embodiment, for <NUM> (¼ inch) or smaller diameter anchors, angle β is approximately <NUM> degrees, and is preferably between <NUM> and <NUM> degrees. For larger size anchors, the angle β could be larger.

The head <NUM> of the example fastener <NUM> is depicted in greater detail in <FIG>. The head <NUM> includes a top portion <NUM> spaced from the shank <NUM>, and a bottom portion <NUM> proximate the shank <NUM>. The top portion <NUM> of the head <NUM> defines a mechanical engaging structure <NUM> which is engageable by an appropriate tool for driving the fastener <NUM>. Thus, in one example embodiment of the present disclosure, the mechanical engaging structure <NUM> includes a hexagonal shaped bolt head that is engageable by an appropriate tool, such as a socket wrench or impact driver. In other embodiments of the present disclosure, other mechanical engaging structures may be utilized, such as a straight slot (engageable by a flathead screwdriver), a cross-shaped slot (engageable by a Phillips head screwdriver), or a hexagonal shaped cavity (engageable by an Allen wrench). Any known or subsequently developed mechanical engaging structures rotatable or drivable by any one of a variety of tools may be used as the engaging structure <NUM> in accordance with the present disclosure.

The bottom portion <NUM> of the head <NUM> includes a bottom surface <NUM>. The bottom surface <NUM> generally faces away from the head <NUM>, and towards the tip <NUM>, along the longitudinal axis A1. The bottom portion <NUM> includes a plurality of ribs <NUM> extending from the bottom surface <NUM> and forming extrusions extending from the bottom surface <NUM>. In an embodiment, the ribs <NUM> are arranged radially around an axis A2 of the head <NUM>, as shown in <FIG>.

In this illustrated example embodiment, as shown in <FIG>, each rib <NUM> includes a leading face 195a and a trailing face 195b that meet at an apex <NUM> of the rib <NUM>. The leading face 195a forms an angle ε<NUM> with respect to the bottom surface <NUM>. Similarly, the trailing face 195b forms an angle ε<NUM> with respect to the bottom surface <NUM>. In this illustrated example embodiment, angle ε<NUM> is greater than angle ε<NUM> such that the leading face 195a is at a sharper angle with respect to a object <NUM>, with which the fastener <NUM> is going to engage, and the trailing face 195b is at a shallower angle with respect to the object <NUM>. In one embodiment, angle ε<NUM> is greater than <NUM> degrees, but less than <NUM> degrees; and angle ε<NUM> is less than <NUM> degrees, but greater than zero degrees.

It should be appreciated that each of the fasteners <NUM> depicted in the Figures is a right-handed threaded fastener <NUM>, such that when they are turned in a clockwise fashion about axis A2 (when looking at the top portion <NUM> of the head <NUM>), the fastener <NUM> is tightened or driven, and when turned in a counter-clockwise fashion about axis A2 (when looking at the top portion <NUM> of the head <NUM>), the fastener <NUM> is loosened or backed out. Thus, when the head <NUM> of the fastener <NUM> is tightened or driven, in a direction shown by rotation R1 in <FIG> and <FIG>, the threads <NUM> and <NUM> of the fastener <NUM> grip the object <NUM>, and the fastener <NUM> is driven into the substrate <NUM>, causing the ribs <NUM> to come into contact with the object <NUM>. When the head <NUM> of the fastener <NUM> is loosened or backed out, in a direction shown by rotation R2 in <FIG> and <FIG>, the threads <NUM> and <NUM> of the fastener <NUM> release their grip on the object <NUM>, and the fastener <NUM> is backed out of the substrate <NUM>, causing the ribs <NUM> to come out of contact with the object <NUM>. In other embodiments of the present disclosure, the fastener <NUM> is left-hand threaded, causing the fastener <NUM> to be tightened or driven in direction R1 and loosened or backed out in direction R2.

As shown in <FIG> and <FIG>, as the fastener <NUM> is tightened (in direction R1), the apex <NUM> and leading edges 195a of the ribs <NUM> come into contact with the object <NUM> as the fastener <NUM> is tightened or driven in the direction of rotation R1. Thus, the sharper angle of the leading edges <NUM> contact the object <NUM> during the tightening process, creating a frictional torsional resistance to the tightening of the fastener <NUM> by "biting" into the surface of the object <NUM> In this way, the leading edges 195a of the ribs <NUM> provide protection against over tightening of the fastener <NUM>, by causing frictional resistance to the tightening. Conversely, when the fastener <NUM> is loosened or backed out in the direction of rotation R2, the shallower angle of the trailing edges 195b of the ribs <NUM> lessen the frictional torsional resistance between the head <NUM> and the object <NUM>, to enable the fastener <NUM> to be removed more easily. In addition to the frictional engagement of the ribs <NUM> with the surface of the object <NUM>, the threads <NUM> and <NUM> of the thread formations <NUM> and <NUM> frictionally engage the inner surfaces of the cavity <NUM> of the substrate <NUM>. For example, the cavity <NUM> may be a recess formed in the substrate <NUM> by pre-drilling the substrate <NUM> to accept the fastener <NUM>.

In an alternative embodiment of the present disclosure, as shown in <FIG> and <FIG>, the ribs <NUM> are formed by a plurality of shaped detents <NUM> or extrusions <NUM> extending from the bottom surface <NUM> of the head <NUM>. The detents <NUM> include a leading portion 198a and a trailing portion 198b. The leading portion 198a is configured to have sharp formations so as to grip and "bite" the object <NUM> as the fastener <NUM> is tightened and driven into the substrate <NUM> and the bottom surface <NUM> approaches and detents <NUM> come into contact with the object <NUM>. For example, the leading portion 198a of the detent <NUM> may include a tooth 199a, and a leading face 199b. The leading face 199b may be oriented at an angle ε<NUM> with respect to the bottom face <NUM> of the head <NUM>, that in a preferred embodiment is a relatively sharp angle so as to cause the leading face 199b to frictionally engage or "bite" into the object <NUM> when the fastener <NUM> is tightened (in direction of rotation R1), similar to the leading face 195a of the embodiment shown in <FIG> and <FIG>. The trailing face 199c of the detent <NUM> is curved and smoothed, as shown in <FIG> and <FIG>. In this way, the trailing face 199c reduces frictional contact with the object <NUM> when the fastener <NUM> is loosened or backed out (in direction of rotation R2), similar to the trailing face 195b of the embodiment shown in <FIG> and <FIG>.

In yet another alternative example embodiment of the present disclosure, as shown in <FIG> and <FIG>, the ribs <NUM> extend from the bottom face <NUM> of the head <NUM> and onto a portion of the shank <NUM>. For example, as shown in <FIG> and <FIG>, the ribs <NUM> may be curved and extend from an outer edge <NUM> of the bottom surface <NUM> of the head <NUM> and along the first portion <NUM> of the shank <NUM>. In this way, a first portion 194a of the rib <NUM> that is radially closer to the center of axis A2 extends relatively farther from bottom surface <NUM>, while a second portion 194b of the rib <NUM> that is radially farther from the center of axis A2 extends relatively less from bottom surface <NUM>. This causes the configuration of the ribs <NUM> to have relatively greater frictional resistance to the object <NUM> at areas of the bottom surface <NUM> that are radially closer to the axis A2, and relatively lesser frictional resistance to the object <NUM> at areas of the bottom surface <NUM> that are radially distant from the axis A2. In this way, when the fastener <NUM> is tightened, the curved ribs <NUM> can mar and "dig" into the object <NUM> closer to the axis A2 (with the second portions 194b of the ribs <NUM>), while leaving areas of the object <NUM> farther from the axis A2 relatively less damaged or displaced (by the first portions 194a of the ribs <NUM>). The ribs <NUM> may be configured to have a radius, or to be otherwise curved, as shown in <FIG>. Alternatively, the ribs <NUM> have a straight edge and extend from the bottom surface <NUM> to the first portion <NUM> of the shank <NUM> in a chamfered configuration. In an embodiment, the apex <NUM> of the ribs <NUM> are generally angled by an angle ω1 with respect to the axis A2 of the head <NUM>, as shown in <FIG>. In the example embodiment shown in <FIG>, ω1 is <NUM> degrees, such that that the total angle ω2 between the apexes <NUM> of opposing ribs <NUM> is approximately <NUM> degrees.

The various structures and configurations of the threaded fastener of the present disclosure provide significant advantages in reducing the likelihood of torsional failure of the fastener and undesirable failures of the fastener from over tightening. For example, the tapering of the shank <NUM> along the third portion <NUM>, and the tapering of the first helical thread formation <NUM> along the third portion <NUM> provide advantages which reduce the risk of the fastener <NUM> failing due to overtightening or large torsional forces. Tapering of the first thread formation <NUM> in the third portion <NUM> of the shank <NUM> reduces the localized frictional torques applied to the third portion <NUM> of the shank <NUM> due to the decreased diameter of the formation <NUM> having less contact surface with the substrate <NUM> in which the fastener <NUM> is driven. Similarly, providing a shank <NUM> which tapers in the third portion <NUM> reduces torsional stresses applied to that area of the shank <NUM> and concentrates higher torsional stresses in the thicker first portion <NUM> of the shank <NUM> closer to the head <NUM>. By reducing the torsional stresses in this third portion <NUM> of the shank <NUM>, instances of failure from overtightening are significantly reduced.

In various embodiment, the structure and configuration of the head <NUM> of the fastener <NUM> further assists in reducing failures from overtightening. Providing an arrangement of ribs <NUM> on the bottom surface <NUM> of head <NUM> creates a frictional impediment to overtightening as the ribs <NUM> engage a surface of the object <NUM> and the substrate <NUM> into which the fastener <NUM> is being driven. Specifically, providing ribs <NUM> will a leading face 195a having a relatively sharper angle α enable the ribs <NUM> to grip or "bite" into the object <NUM> as the bottom surface <NUM> comes into contact with the object <NUM> being attached to the substrate <NUM> by the fastener <NUM>, thereby causing a frictional resistance to overtightening. However, providing trailing faces 195b on the ribs <NUM> with a relatively shallower angle β enables the fastener <NUM> to be loosened, backed out and removed much more easily.

Referring now to <FIG> and <FIG>, another alternative example embodiment of the threaded fastener of the present disclosure is generally illustrated. In this alternative example illustrated embodiment, the fastener <NUM> includes a head (not shown), a shank <NUM>, a first or primary thread formation <NUM> extending outwardly from the shank <NUM>, and a second or secondary thread formation <NUM> extending outwardly from the shank <NUM>.

In this alternative example illustrated embodiment, the first or primary helical thread formation <NUM> of the threaded fastener <NUM> is formed with a plurality of grooves such as grooves <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> that are respectively each partially defined by a straight cutting edge. For example, groove <NUM> is defined by a first straight cutting edge or surface <NUM> and a second edge or surface <NUM>. The first straight cutting edge or surface <NUM> and the second edge or surface <NUM> intersect at an acute angle at or along an intersection line <NUM>. In certain embodiments, the acute angle is approximately <NUM> degrees, but it should be appreciated that this angle may vary in accordance with the present disclosure. The straight cutting edge <NUM> assists the thread formation or thread <NUM> in cutting into the substrate (such as a concrete substrate). This enables the threaded fastener <NUM> to form its path more efficiently, reduces necessary installation torque, and reduces the likelihood of breakage of the threaded fastener <NUM> during installation or use.

It should be appreciated that all of the grooves are identically configured in this example embodiment, but that one or more of the grooves may be alternatively configured. It should also be appreciated that for this alternative embodiment, the head may be any of the various different heads discussed herein or may be an alternatively configured head. It should also be appreciated that for this alternative embodiment, the shaft may be any of the various different shafts discussed herein or may be an alternatively configured shaft. It should further be appreciated that for this alternative embodiment, the quantity of thread formations may vary. It should further be appreciated that for this alternative embodiment, the configuration of the thread formations (besides or in addition to the grooves) may vary.

It should be appreciated from the above that each of the different alternatives for the head, the shank, and the threads may be combined in any suitable combination in accordance with the present disclosure.

It should also be appreciated from the above, that in various embodiment, the present disclosure provides a fastener including a head; a shank connected to the head at a first end and forming a tip at a second end, the shank having a first portion proximate the head, a second portion adjacent to the tip, and a third portion between the first and second portions, the shank having a longitudinal axis extending from the head to the tip, the first portion having a substantially constant diameter along a length of the shank, the second portion having a substantially constant diameter along the length of the shank, and the third portion having a diameter that decreases along the length of the shank in a direction along the longitudinal axis from the head to the tip; and a first helical thread formation having a thread form thereon formed from two portions disposed upon opposite lateral sides of the thread form, the thread form having a root, the root positioned along the second and third portions of the shank; wherein an outer diameter of the first helical thread formation on the third portion of the shank increases along the length of the shank in a direction along the longitudinal axis from the head to the tip.

In certain such embodiments, the outer diameter of the first helical thread formation is substantially constant on the second portion of the shank.

In certain such embodiments, the fastener includes a second helical thread formation between the first helical thread formation.

In certain such embodiments, an outer diameter of the second helical thread formation is smaller than the outer diameter of the first helical thread formation.

In certain such embodiments, the fastener includes a plurality of second helical thread formations between the first helical thread formation.

In certain such embodiments, an outer diameter of the plurality of second helical thread formations is smaller than the outer diameter of the first helical thread formation.

In certain such embodiments, an outer surface of the third portion of the shank forms an angle α with the longitudinal axis.

In certain such embodiments, the outer diameter of the first helical thread formation on the third portion of the shank forms an angle β with the longitudinal axis.

In certain such embodiments, α is approximately <NUM> degree, and β is approximately <NUM> degree.

It should be further appreciated from that above that in various other embodiments, the present disclosure provides a fastener including a head; a shank connected to the head at a first end and forming a tip at second end, the shank have a first portion proximate the head, a second portion proximate the tip, and a third portion between the first and second portions; and a first helical thread formation having a thread form thereon formed from two portions disposed upon opposite lateral sides of the thread form, the thread form having a root, the root positioned along the second and third portions of the shank; the head including a top portion distal from the shank, and a bottom portion adjacent to the shank, the top portion defining an engaging structure engageable by a tool, the bottom portion including a bottom surface and a plurality of ribs extending from the bottom surface arranged radially around an axis of the head, the ribs extending outward from the bottom surface in a direction towards the tip, the ribs configured to frictionally engage a face of a object attachable to a substrate into which the fastener is driven as the ribs approaches and comes into contact with the object being attached to the substrate by the fastener.

In certain such embodiments, the first helical thread formation is formed with a plurality of grooves that are respectively each partially defined by a straight cutting edge.

In certain such embodiments, each of the plurality of ribs includes a leading face and a trailing face, wherein the leading face is configured to engage the face of the object as the fastener is driven into the substrate.

In certain such embodiments, the leading face forms an angle ε<NUM> with the bottom surface.

In certain such embodiments, ε<NUM> is greater than <NUM> degrees and less than <NUM> degrees.

In certain such embodiments, a portion of each of the plurality of ribs is connected to and extends along the first portion of the shank.

In certain such embodiments, an outer diameter of the first helical thread formation increases in the third portion along the length of the shank in an axial direction from the head to the tip.

It should be further appreciated from that above that in various embodiments, the present disclosure provides a fastener including a head; a shank connected to the head at a first end and forming a tip at a second end, the shank having a first portion proximate the head, a second portion adjacent to the tip, and a third portion between the first and second portions, the shank having a longitudinal axis extending from the head to the tip; and a first helical thread formation formed with a plurality of grooves that are respectively each partially defined by a straight cutting edge.

In certain such embodiments, at least one of the grooves is defined by a first straight cutting edge and a second edge that intersect at an acute angle along an intersection line.

In certain such embodiments, the first portion has a substantially constant diameter along a length of the shank, the second portion has a substantially constant diameter along the length of the shank, and the third portion has a diameter that decreases along the length of the shank in a direction along the longitudinal axis from the head to the tip.

In certain such embodiments, the outer diameter of the first helical thread formation on the third portion of the shank increases along the length of the shank in a direction along the longitudinal axis from the head to the tip.

In certain such embodiments, the fastener includes a second helical thread formation extending from the shank.

Claim 1:
A fastener (<NUM>; <NUM>) comprising:
a head (<NUM>);
a shank (<NUM>; <NUM>) connected to the head at a first end (<NUM>) and forming a tip (<NUM>) at a second end (<NUM>), the shank having a first portion (<NUM>) proximate the head, a second portion (<NUM>) adjacent to the tip, and a third portion (<NUM>) between the first and second portions, the shank having a longitudinal axis (A1) extending from the head to the tip; and
a first helical thread formation (<NUM>; <NUM>) formed with a plurality of grooves (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>) that are respectively each partially defined by a straight cutting edge (<NUM>, <NUM>);
wherein the first portion (<NUM>) has a substantially constant diameter along a length of the shank (<NUM>), the second portion (<NUM>) has a substantially constant diameter along the length of the shank, and the third portion (<NUM>) has a diameter that decreases along the length of the shank in a direction along the longitudinal axis (A1) from the head (<NUM>) to the tip (<NUM>),
characterised in that an outer diameter of the first helical thread formation (<NUM>; <NUM>) on the third portion (<NUM>) of the shank (<NUM>) increases along the length of the shank in a direction along the longitudinal axis (A1) from the head (<NUM>) to the tip (<NUM>).