WO2020083458A1 - Spirally ridged self-locking dowel-type fastener - Google Patents

Abstract

A dowel-type fastener is disclosed. The spirally ridged self-locking dowel-type fastener has an optimized shape, to achieve a less resistant and non-destructive penetration, a considerably stronger fastening interaction, and a higher axial withdrawal strength. Its functional lateral surface (5) comprises a plurality of parallel spiral ridges (7) defined by pairs of leading slopes (10) and trailing slopes (13). The leading slopes (10) are generally smooth surfaces, spanning between a channel bottom (11 ) and a smooth helix ridgeline (12), designed to slide the fastener into a penetrated receiving member (6). The trailing slopes (13) have a rough form designed to bite the receiving member {6} into a locked position.

Description

SPIRALLY RIDGED SELF-LOCKING DOWEL-TYPE FASTENER Technical Field

The invention relates generally to fasteners and more particularly, the present invention relates to the subject matter of dowel-type fasteners, having a unique configuration along its shank.

Background Art

Joints with dowel-type fasteners are the most common fixings in a wide range of different structures, such as wood, interior, masonry and concrete constructions or industrial applications. Dowel-type fasteners include bolts, screws, dowels, inserts, and nails. The main characteristic of this type of connections is a relatively good lateral load resistance. On the other hand, especially simple dowels have a generally inferior axial withdrawal strength, also referred as pulling out resistance of the dowel.

Nails are the least sophisticated and most easy-to-use dowel-type fastening means. They are quick and straight pushable into place, possibly by a simple percussive tool such as a hammer. Producing the least friction, plain nails are the easiest to install. However, as the holding power of such impact-drivable dowel-type fasteners is generally achieved by pressure and friction of displaced penetrated material bearing down on the shank of the fastener, smooth shank nails also have the least ability to be gripped by the penetrated material.

Another drawback of similar impact-drivable dowel-type fasteners can be a repeatedly applied external loosening force or vibration of the construction, to which the fasteners are applied, which will also loose them with the lapse of time, thereby reducing the strength and the reliability of the joint. A further possible undesirable consequence of the fastener’s loosening is the squeaking of the connection, which is especially problematic in some wood constructions.

Moreover, in wood constructions subjected to moisture changes from normal atmospheric variations, the withdrawal resistance of smooth-shank nails also diminishes in time. The withdrawal loads for plain nails, driven into wood that is exposed to wide alternating changes in moisture content, may be reduced as much as 75 percent below the original values soon after driving.

Differently from common nails, a screw creates a superior interlocking joint with the penetrated material, that has a greater holding power, but as torque driven, is more complex and demanding to install. In order to retain its original advantages, especially the installation easiness, there have been developed many particular types of nails for ordinary or special uses. To create a screw-like interlocking joint, having an improved holding power and supplying a higher resistance to withdrawal than provided by the common nail, the shanks of some nails are ringed, threaded, spiraled, and/or barbed.

Patents disclosing information relevant to such fasteners include: US 1649049 A SPIRAL ROLLED PRODUCTS CO INC - Wood screw , US 2025961 A JAMES STONE HERMAN 19350806 - Wire nail, EP 0212068 A ROCKENFELLER KG 19870304 - Nail with a head at one end of the shaft and a point at the other, CA 2583890 A UNIVERSAL FASTENER OUTSOURCING 20071007 - Mushroom compaction and asymmetric-thread impact-drivable screw, US 2004047713 A JUNG YOUNG JAE 20040311 - Screwed nail, WO 2007081963 A STANLEY FASTENING SYS LP 20070719 - Nail with multiple shank deformations, US 5375957 A LYSAGHT AUSTRALIA LTD 19941227 - Impact drivable fastener, EP 0164432 B WAKAI & CO. LTD 19880203 - Twisted nail, and EP 2368048 A RAIMUND BECK NAGELTECHNIK GMBH 20110928 - Screw nail.

Another problem with the known ringed or barbed dowel-type fasteners is that, apart from a higher withdrawal resistance form, they generally also have a greater driving-in resistance, wherein the higher required driving force results in a higher penetrated material’s destruction to weaken the final fasteners holding power. In this aspect, its penetration resistance fundamentally limits the pulling out resistance of the dowel-type fastener. Differently, the penetration of a smooth and steeply spiraled dowel-type fastener is less resistant and destructive. Thus, some combinations of steeply spiraled and barbed concepts are trying to get the best of both worlds.

Patents disclosing information relevant to combined steeply spiraled and barbed fasteners include: US 2269708 A ROBERT B DICKSON 19400122 - Fastening element, US 2011280686 A MAHDI MOHAMMED ISA 20111117 – Fastener, DE 2038885 A ROCKENFELLER KG 19720210 – Schraubnagel, US 2009155021 A ILLINOIS TOOL WORKS 20090618 - Deformed shank fastener, US 5741104 A ILLINOIS TOOL WORKS 19980421 - Steel fastener having grooved shank, US 3233498 HANDJA JOSEPH A 19660208 - Self-locking nail, DE 1978882U KIRCHHOFF SIEGFRIED 19680215 – Duebel, and US 2013017032 A ILLINOIS TOOL WORKS 20130117 - Spire insert with ring-shank nicking.

While penetrating, the spiral fastener interacts with the penetrated material, mainly by its leading surfaces and most forcefully at the spiral ridgelines. Hence, the known screwed and ringed or barbed shank dowel-type fasteners' combinations, having rough, notched or serrated leading surfaces and ridgelines, are limited in their teaching and utilization, as their shapes contribute highly to the penetration’s resistance and penetrated material’s destruction, which serves poorly the overall fastener’s pulling out resistance. To overcome the known fasteners limitations and increase the fastening power and reliability, an improved spirally ridged self-locking dowel-type fastener is needed.

The double ended fasteners and inserts are generally used as anchoring means in many industrial applications, masonry, concrete and wood constructions, etc. Besides, as a particularly challenging aspect, there is in some cases a necessity to produce blind joints, so that the fastener itself is invisible after the joint has been formed. In high-quality furniture and other special constructions for example, the appearance of exposed mechanical fasteners such as nails, bolts, or screws is inappropriate. Although usual nails, bolts, and screws are generally exposed and visible, there are many prior art solutions of special inserts and double-ended impact-drivable dowel-type fasteners that can be concealed into a blind joint.

Patents disclosing information relevant to impact-drivable double-ended dowel-type fasteners include: DE 3309954 A FISCHER WALTER 19840920 - Joining element in particular for invisible joining of planar parts in furniture, US 1354549 A GILMER JOHN T 19201005 - Dowel pin, US 2002164228 A MARTIN DANNIE E 20021107 - Double ended fastener, EP 0150906 A OLLIS WILLIAM JOHN BERNARD 19850807 - Helical dowel, DE 19709574 A ELISCHER WERNER 19980910 - Nail fixture for esp. soft materials e.g. wood or fibre blocks has two-ended, DE 10315319 A SPRICH KLAUS 20041014 – Doppelspitz, EP 0358223 A ASTL ARNO 19900314 - Connection element, especially a dowel, and US 4350464 A BROTHERS RICHARD 19820921 - Anchor bolt for concrete.

Push-in insert nuts are similar in concept and utilization to double-ended impact-drivable fasteners. Patents disclosing information relevant to push-in insert nuts include: DE 1978882U KIRCHHOFF SIEGFRIED 19680215 - Duebel, GB 1549199 A BARNSDALE A D 19790801 – Insert, DE 4000782 A BOELLHOFF & CO 19910808 - Threaded insert, DE 19856611 A BOELLHOFF GMBH 20000615 - Metallic insert, and US 2013017032 A ILLINOIS TOOL WORKS 20130117 - Spire insert with ring-shank nicking.

The known impact-drivable double-ended fasteners and insert nuts are related to and limited by its prior art impact-drivable dowel-type fasteners' context. Therefore, to boost the solution to anchoring and blind joint production, an improved impact-drivable dowel-type fastener concept is needed.

Disclosure of Invention

The spirally ridged self-locking dowel-type fastener’s inventive concept takes a different approach from that taken by known fasteners and it is grounded upon different principles to the prior art. It originates from a broader understanding of the elastic-plastic interaction between an impact-drivable dowel-type fastener and a receiving member. It employs this understanding to provide a distinct fastener having an optimized shape to achieve a less resistant and non-destructive penetration, a considerably stronger fastening interaction, and a higher axial withdrawal strength over that of other known configurations.

The spirally ridged self-locking dowel-type fastener has a functionally formed lateral surface comprising a plurality of parallel spiral ridges defined by pairs of leading and trailing slopes. The leading slopes are generally smooth surfaces, spanning between a channel bottom and a smooth spiral ridgeline, designed to slide the fastener into a penetrated receiving member. The trailing slopes, on the other hand, have a rough, barbed or toothed form designed to bite the receiving member into a locked position.

The claimed fastener’s shape efficiently harnesses the different forces, actions and reactions, taking part in its introduction into a receiving member. An axial direction thrust, as a primary external force applied to the fastener, propels it into the receiving member. In the following collision, most of the fastener’s impact force exerts on its ridgelines and leading slopes. As a result, the sharp and smooth spiral ridgelines cut a channeled way and guide the fastener to rotate into the penetrated material. The smooth leading slopes’ impact into the substrate transfers part of the axial direction thrust energy into a useful elastic deformation of the fastener and receiving member system. The elastic deformation dilates the receiving material’s entering channels, thus releasing the trailing slopes and opening the way to the fastener’s insertion. As the impact overcomes the static friction between the fastener and the substrate, the fastener slides inside the receiving member. The smooth leading surfaces and smooth spiral ridgelines minimize the slide’s friction and the penetrated material destruction. As the fastener slides, a system’s elastic reaction prevails, returning the deformation toward its original shape and closing the entering channels. In the process part of its elastic energy transfers into a secondary reaction that axially spins the fastener and forces the toothed trailing part of the spiral formation to firmly bite the receiving member into a locked position. Ideally, the inward pushing motion causes minimal energy dissipation, so that most of its energy transforms in the twisting and gripping reaction of the fastener. The result of the said introduction is the interlocking of the fastener with the receiving member in a deeper and rotated position. The described introduction can be a single procedure or it can be easily repeated, until reaching the final fastening position.

The strong, non-destructive interaction creates a fastener’s superior withdrawal resistance and a high load capacity. Any additional shocks, vibrations or pulling out forces tend to engage the toothed trailing part of the fastener, increasing the bite into the penetrated material and reinforcing its fastening grip over a long run. As the axial pulling out force does not transfer into a torque needed to unlock the fastener from its locked position, a disengagement and fastener’s extraction is only possible by applying an intentional axial rotation to the fastener.

Further benefits of the present invention will become apparent after a careful reading of the detailed description, with appropriate reference to the accompanying drawings.

Brief Description of Drawings

The features of the invention, believed to be novel, are set forth with particularity in the appended claims. The invention itself, however, may be best understood by reference to the following detailed description of some exemplary embodiments of the invention, taken in conjunction with the accompanying drawings, in which:

Figs. 1A-1E are a side view (Fig. 1A), a partial vertical cross section view (Fig. 1B), a perspective section view (Fig. 1C), a horizontal cross section view (Fig. 1D) and a partial side view (Fig. 1E) of an embodiment of a spirally ridged self-locking dowel-type fastener, embodying the principles of the present invention;

Figs. 2A-2E are a side view (Fig. 2A), a partial vertical cross section view (Fig. 2B), a perspective section view (Fig. 2C), a horizontal cross section view (Fig. 2D) and a partial side view (Fig. 2E) of an alternate embodiment of the spirally ridged self-locking dowel-type fastener;

Figs. 3A-3D are a side view (Fig. 3A), a vertical cross section view (Fig. 3B), a perspective view (Fig. 3C), and a horizontal cross section view (Fig. 3D) of still another alternate embodiment of the spirally ridged self-locking dowel-type fastener;

Figs. 4A-4D are a side view (Fig. 4A), a vertical cross section view (Fig. 4B), a perspective section view (Fig. 4C), and a horizontal cross section view (Fig. 4D) of another alternate embodiment of the spirally ridged self-locking dowel-type fastener; and

Figs. 5A-5D are a side view (Fig. 5A), a vertical cross section view (Fig. 5B), a perspective section view (Fig. 5C), and a horizontal cross section view (Fig. 5D) of yet another alternate embodiment of the spirally ridged self-locking dowel-type fastener.

Description of Embodiments

Since the present invention may assume many alternative variations and embodiments, it is to be understood that the embodiments described hereinafter and illustrated in the accompanying drawing figures are simply exemplary and should not be considered as limiting. Any equivalent variation and modification, made according to appended claims, is all covered by the claims, claimed by the present invention.

For purposes of the description hereinafter, spatial orientation terms, if used, shall relate to the referenced embodiment, as it is oriented in the accompanying drawing figures, or otherwise described in the following detailed description.

Figs. 1A through 5D illustrate various embodiments of the claimed dowel-type fastener. The dowel-type fastener has a monolithic body of metal or other relatively hard material that includes a shank 1, having a functional lateral surface 5 therein. The fastener installs by applying an external push, which transfers into an axial thrust of the fastener, propelling it into a receiving member 6. The functional lateral surface 5 reduces the penetration resistance and increases the pulling out resistance of the dowel-type fastener. In each of the illustrated embodiments, the fasteners are formed with a plurality of alternately disposed ridges 7 and channels 8 being spirally wrapped around a vertical axis 2. The top of each of the ridges 7 forms a generally cutting sharp and smooth spiral ridgeline 12, designed to cut a spirally channeled way into the penetrated material. Pairs of two side slopes, one being a downward leaning leading slope 10, and the other being a trailing slope 13, form the sides of the said ridges 7. Each of the said leading slopes 10, spanning between a lower channel bottom 11 and the spiral ridgeline 12 in a form of a smooth spiral surface, is designed to non-destructively engage the penetrated material, elastically dilating and opening the entering channels. As the fastener’s impact force overcomes the static friction between the leading slope 10 and the substrate, the fastener slides smoothly inside the receiving member 6. As the fastener slides, an elastic reaction prevails, transferring part of its energy into a secondary reaction force, axially spinning the fastener and forcing the said rough trailing slope 13 to engage the penetrated material, and closing the said entering channels. Each of the said rough trailing slopes 13 is notched into a toothed form of a flight of spiral stairs, designed to bite the receiving member 6 into a locked position. An upper tread 14 and a lower raiser 15, the two meeting at a tread’s front edge 16, form each step of the said spiral stairs. The said tread 14 is an upward facing interfering surface, designed to interlock a penetrated receiving member 6, providing resistance against axial withdrawal.

The generally smooth raiser 15 extends approximately over the step’s vertical raise height 17, and connects the next lower step’s tread 14 at a backside edge 18.

The front edge 16, horizontally projecting over the underlying said raiser 15 and part of the next lower step’s said thread 14, forms a sharp nosing 26, designed to bite deeply into the penetrated material, and guarantee a larger said thread’s 14 interlocking surface.

The leading slope 10 and the raiser 15 of two adjacent said ridges are smoothly joined at a common channel bottom 11, in a bow-like outline, to sustain the system’s elastic deformation. By estimation, in order to transfer an adequate part of the deforming pressure to a broader system’s material, the fastener’s channel depth 19 should not exceed 1/3 of its channel width 20.

Figs. 1A-1E illustrate a dowel-type fastener embodied in a form of a spiral nail 27. The spiral nail’s 27 lower leading portion 3 tapers downward in a form of a penetrating tip. The upper trailing portion 4 forms a head 28. The constant ridgeline angle 9, of about 75⁰ to the horizontal plane, and the constant steps’ vertical raise heights 17 along the entire said functional lateral surface’s 5 height make this fastener embodiment a universal spiral nail, capable of being installed by applying a single forceful axial direction thrust, as for example by a nailing gun, or by applying multiple repetitive axial direction thrusts or vibrations, as for example by a regular hammer, palm nailer, auto hammer, and the like.

Figs. 2A-2E illustrate a dowel-type fastener embodied in a form of a double-ended dowel 29, also capable of binding two receiving members into a blind joint. In order to facilitate the insertion into a receiving member’s pre-drilled hole, the double-ended dowel’s 29 leading portion 3 is frustoconically tapered. The said upper trailing portion 4 is an approximately mirrored form of the combined lower leading portion 3 and functional lateral surface 5. The two fastener’s ends are mirrored at a horizontal plane and share the same vertical axis 2. The constant ridgeline angle 9, of about 50⁰ to the horizontal plane, and the constant steps’ vertical raise heights 17 along the whole said functional lateral surface’s 5 height, make this fastener capable of being installed by applying a single forceful axial direction thrust, or by applying multiple repetitive axial direction thrusts or vibrations, as for example by a percussive tool.

Figs. 3A-3D illustrate a dowel-type fastener embodied in an alternative form of a double-ended dowel 29, similar in form and function to the embodiment of figs. 2A-2E. Moreover, this dowel screw or dowel bolt embodiment of the fastener is usable as an anchoring mean for joining dissimilar materials as well. The said upper trailing portion 4 is a form of a different type of threaded dowel 30, such as a screw, or a bolt, and the like, sharing the same vertical axis 2. The leading portion 3 and the trailing portion 4 include a shape adaptation 33 to engage a tool, capable of applying a torque to the fastener. The leading portion’s 3 said shape adaptation 33 is a hexagonal socket, to be engaged by a hex key or the like. The trailing portion’s 3 said shape adaptation 33 is a hex shaped collar, to be engaged by an open-ended spanner or the like. The said shape adaptations 33 are useful for either the positioning or the extraction of the fastener.

Figs. 4A-4D illustrate a dowel-type fastener embodied in a form of an insert nut 31 that includes a female axial opening 32, sharing the same said vertical axis 2. The said female axial opening 32 includes a female thread therein, designed to mate a complementary male threaded dowel 35. The insert nut’s 31 leading portion 3 is frustoconically tapered in order to facilitate the insertion into a receiving member’s pre-drilled hole 34. The insert nut 31 has a constant ridgeline angle 9 of about 60⁰ to the horizontal plane, and equal steps’ vertical raise heights 17 along the entire said functional lateral surface’s 5 height. Its form is particularly suitable for a variety of “push-in” type installation methods, including a method of multiple repetitive axial direction thrusts or vibrations, as for example applied by a percussive tool. Being thrust-driven, the insert nut 31 can also bind two members into a blind joint. The insert nut’s 31 upper trailing portion 4 can be either dematerialized or formed as a head 28, as represented by a dashed line. The insert nut 31 embodiment having a dematerialized upper trailing portion 4 is especially appropriate for producing a blind joint.

Figs. 5A-5D illustrate a dowel-type fastener embodied in an alternate form of a spiral nail 27, particularly suitable for a single axial direction thrust installation method, as for example by a nailing gun, into a relatively softer elastic material, such as wood, plastics, etc. The spiral nail’s 27 lower leading portion 3 tapers in a form of a penetrating tip. The upper trailing portion 4 forms a head 28. The functional lateral surface 5 comprises a total number “n” of four equally disposed ridges 7. The said ridgeline angle 9 logarithmically increases from about 80⁰ at the lowest point, to a ridgeline angle 9 of about 90⁰ at the highest point of the said functional lateral surface 5. As the spiral nail 27 penetrates the receiving member 6 in a single thrust, the function of elastically dilating and opening the receiving member’s 6 entering channels is predominantly taken over by the lower part of the said leading slope 10, while the penetrated material’s elastic reaction spreads over its entire surface. In order to achieve an optimal receiving member 6 material’s elastic reaction, the spiral rotation angle 25 of each ridge 7 should preferably not exceed 45⁰ according to claim 8. The said raiser 15 is formed by two generally smooth surfaces, jointly connecting the said spiral ridgeline 12 to the adjacent channel bottom 11. The first riser’s surface 21 meets the said tread 14 at a said front edge 16, and the second riser’s surface 22 meets the said tread at a side edge 23. Both, the said front edge 16 and the said side edge 23, are formed as sharp cutting edges, and are joined at a pointed thread’s side corner 24 to achieve an aggressive single bite of the fastener into the final fastened position.

Claims (15)

1. A dowel-type fastener comprising a shank (1) extending in a vertical axis (2) from a lower leading portion (3) to the upper trailing portion (4), wherein at least part of the said shank (1) comprises a functional lateral surface (5) designed to efficiently penetrate and interlock a receiving member (6), wherein the said functional lateral surface (5) comprises a plurality of alternately disposed ridges (7) and channels (8) that are spirally wrapped around the said vertical axis (2) at a ridgeline angle (9) of at least 45⁰ to the horizontal plane; the said ridges (7) are formed by pairs of two side slopes, one said side slope being a downward leaning leading slope (10) in a form of an ideally smooth spiral surface spanning between a lower channel bottom (11) and an ideally smooth spiral ridgeline (12), and the other said side slope being a rough trailing slope (13) spanning between the said spiral ridgeline (12) and the upper said channel bottom (11).
2. The dowel-type fastener according to claim 1, wherein the said rough trailing slope (13) is notched into a toothed form of a flight of spiral stairs, wherein each step of said spiral stairs is formed by an upper tread (14) and a lower raiser (15), the two meeting at a tread’s front edge (16), wherein the said tread (14) is a preferably single upward facing surface, and the said raiser (15) extends approximately over a step’s vertical raise height (17) and connects to a backside edge (18) of the next lower step’s said tread (14) in a form of at least one generally smooth surface.
3. The dowel-type fastener according to claim 2, wherein the said raiser (15) smoothly joins the said leading slope (10) of the upper adjacent said ridge (7) in the upper said channel bottom (11), and the channel depth (19) of each of the said channels (8) does not exceed 1/3 of its channel width (20).
4. The dowel-type fastener according to claim 2 or 3, wherein the said raiser (15) is a preferably single smooth surface that joins the said leading slope (10) of the same said ridge (7) at the said spiral ridgeline (12).
5. The dowel-type fastener according to claim 2 or 3, wherein the said raiser (15) is formed of preferably two generally smooth surfaces that jointly connect the said spiral ridgeline (12) to the upper said channel bottom (11); the first riser’s surface (21) meets the said tread (14) at the said front edge (16), and the second riser’s surface (22) meets the said tread at a tread’s side edge (23), wherein the said front edge (16) and the said side edge (23) are joined at a thread’s side corner (24).
6. The dowel-type fastener according to any of the claims 1 to 5, wherein the said ridgeline angle (9) and the said steps’ vertical raise heights (17) are constant along the whole said functional lateral surface (5).
7. The dowel-type fastener according to any of the claims 1 to 5, wherein the said ridgeline angle (9) and/or the said step’s vertical raise heights (17) are changing along the said functional lateral surface’s (5) height.
8. The dowel-type fastener according to claim 7, wherein the total number of equally disposed said ridges (7) is n, and the spiral rotation angle (25) of each ridge does not exceed 180⁰/n.
9. The dowel-type fastener according to any of the claims 2 to 8, wherein the said front edge (16) horizontally projects over the underlying said raiser (15) and part of the next lower step’s said thread (14) in a form of a nosing (26).
10. The dowel-type fastener according to any of the claims 1 to 9, wherein the said front edge (16) and/or the said side edge (23) and/or the said spiral ridgeline (12) are formed as sharp cutting edges.
11. The dowel-type fastener according to any of the claims 1 to 10, embodied in a form of a spiral nail (27), wherein the said upper trailing portion (4) forms a head (28) and the said lower leading portion (3) forms a penetrating tip.
12. The dowel-type fastener according to any of the claims 1 to 10, embodied in a form of a double-ended dowel (29), wherein the said upper trailing portion (4) comprises either an approximately mirrored form of the said functional lateral surface (5) or a form of a different type of threaded dowel (30), such as a screw, or a bolt, and the like, sharing the same said vertical axis (2).
13. The dowel-type fastener according to any of the claims 1 to 10, embodied in a form of an insert nut (31) that includes a female axial opening (32) sharing the same said vertical axis (2), wherein the said female axial opening (32) may be threaded to mate a complementary male threaded dowel (35).
14. The dowel-type fastener according to any of the claims 1 to 13, wherein the said leading portion (3) and/or the said trailing portion (4) include a shape adaptation (33) to engage a tool capable of applying a torque to the fastener.
15. The dowel-type fastener according to any of the claims 1 to 14, having at least part of the said shank (1) coated in a lubricative and/or adhesive material, such as vinyl or other, to ease penetration and/or additionally fix the fastener to the penetrated said receiving member (6).

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