CROSS-REFERENCE TO RELATED APPLICATION(S)

[001] This application claims the benefit under 35 U.S.C. § 1 19(e) to U.S. Provisional Application 63/406,579, filed September 14, 2022, and entitled Formwork Ties, and U.S. Provisional Application 63/427,185, filed November 22, 2022, and entitled Formwork Ties, which are hereby incorporated herein by reference in their entirety for all purposes.

TECHNICAL FIELD

[002] The disclosure relates to concrete forming and particularly ties used in formwork systems.

BACKGROUND

[003] As would be appreciated ties are used with formwork systems to resolve lateral forces exerted on the formwork by freshly placed concrete. Prior known taper ties for formwork are traditionally produced by two methods: machining complete from a stock steel material or crimping a steel sleeve onto a continuously threaded steel bar. Each of these known methods compromises in terms of strength, cost to produce, and durability.

[004] In the case of machined taper ties, the stock material is expensive, owning to the need to be made of a high strength material capable of carrying the desired loads. The stock material also must be oversized, larger than the finished part, with the excess machined away and therefor wasted. As would be understood, machined material is made weaker because the grain structure of the metal is interrupted during the machining process. Heat treatment, a separate and costly process, can be used to increase the strength of cut threads.

[005] For implementations with a crimped sleeve design, only the tapered portion of the part is machined, at the expense of a crimping operation, making the crimped sleeve solution less costly than a fully machined tie. In these implementations, the taper is not load carrying and can be made of a less costly material.

[006] Still further, with prior known taper tie designs, despite being produced with high strength steels, small dents and indentations, as well as, surface roughness of the machined surface have a negative impact to the usage / durability of these prior known taper ties. Prior known sleeved taper ties may be dented or the crimps may loosen, causing the part to fail.

[007] There is a need in the art for taper ties that are less expensive to produce, strong, and durable.

BRIEF SUMMARY

[008] A taper tie comprising a rolled threaded rod and an overmolded element, wherein the overmolded element is molded directly on the rolled threaded rod to create a tapered section.

[009] In Example 1 , a taper tie comprising a threaded rod and an overmolded element, wherein the overmolded element is molded directly on the rolled threaded rod to create a tapered section.

[010] Example 2 relates to the taper tie of Example 1 , wherein the threaded rod is a hot rolled steel rod. [011] Example 3 relates to the taper tie of any of Examples 1 -2, wherein the threaded rod has an oblong cross-section comprising two flat faces and two deformed thread faces.

[012] Example 4 relates to the taper tie of any of Examples 1 -3, wherein the overmolded element is comprised of one or more of TRU (thermoplastic urethane), thermoplastic, thermoset plastic, and die cast metal alloys.

[013] Example 5 relates to the taper tie of any of Examples 1 -4, wherein the overmolded element is comprised of thermoplastic urethane.

[014] Example 6 relates to the taper tie of any of Examples 1 -5, wherein the overmolded element is mechanically interlocked with the threaded rod.

[015] Example 7 relates to the taper tie of any of Examples 1 -6, wherein the overnolded element comprising a sloped section at each end of the overmolded element.

[016] Example 8 relates to the taper tie of any of Examples 1 -7, wherein the overmolded element is shaped to form a void in concrete during forming.

[017] Example 9 relates to the taper tie of any of Examples 1 -8, wherein the threaded rod is a cold rolled steel rod.

[018] Example 10 relates to the taper tie of any of Examples 1 -9, further comprising a bonding agent on the cold rolled steel rod providing bonding between the cold rolled steel rod and the overmolded element.

[019] Example 1 1 relates to the taper tie of any of Examples 1 -10, wherein the bonding agent is a heat sensitive adhesive.

[020] Example 12 relates to the taper tie of any of Examples 1 -1 1 , wherein the threaded rod is between about 36 inches to about 52 inches in length.

[021] Example 13 relates to the taper tie of any of Examples 1 -12, wherein the overmolded element is between about 15 inches to about 37 inches in length.

[022] Example 14 relates to the taper tie of any of Examples 1 -13, wherein the overmolded element tapers from about 1 1/16 inches in diameter to about 7/8 inches in diameter.

[023] Example 15 relates to the taper tie of any of Examples 1 -14, wherein the threaded bar is a 5/8 inch galvanized steel bar.

[024] In Example 16, a formwork tie, comprising a hot-rolled threaded steel rod and an overmolded element formed around a center portion of the hot-rolled threaded steel rod, wherein the overmolded element is tapered decreasing in diameter along a length of the overmolded element, wherein the hot-rolled threaded steel rod and the overmolded element are mechanically interlocked.

[025] Example 17 relates to the formwork tie of Example 16, wherein the overmolded element is comprised of one or more of TPU (thermoplastic urethane), thermoplastic, thermoset plastic, and die cast metal alloys.

[026] Example 18 relates to the formwork tie of any of Examples 16-17, wherein the overmolded section element from about 1 1/16 inches in diameter to about 7/8 inches in diameter. [027] Example 19 relates to the formwork tie of any of Examples 16-18, wherein the hot-rolled threaded steel rod is galvanized or electroplated.

[028] Example 20 relates to the formwork tie of any of Examples 16-19, wherein the hot-rolled threaded steel rod has an oblong cross-section comprising two flat faces and two deformed thread faces.

[029] While multiple embodiments are disclosed, still other embodiments of the disclosure will become apparent to those skilled in the art from the following detailed description, which shows and describes illustrative embodiments of the invention. As will be realized, the disclosure is capable of modifications in various obvious aspects, all without departing from the spirit and scope of the disclosure. Accordingly, the drawings and detailed description are to be regarded as illustrative in nature and not restrictive.

BRIEF DESCRIPTION OF THE DRAWINGS

[030] FIG. 1 shows a prior art taper tie.

[031] FIG. 2 is a cutaway view of the disclosed taper tie showing the different materials — threaded rod and overmolded material, according to one implementation.

[032] FIG. 3 is an end-long view of a hot rolled threaded bar, according to one implementation.

[033] FIG. 4 is a partial diagram of a taper tie, according to one implementation.

[034] FIG. 5 is a perspective view of a taper tie, according to one implementation.

[035] FIG. 6 is a diagram of a threaded bar, according to one implementation.

[036] FIG. 7 is a perspective view of a taper tie in use, according to one implementation.

DETAILED DESCRIPTION

[037] Described herein are taper ties used in concrete forming, that is ties that hold forms against lateral pressure exerted by pouring concrete and hold the forms in the desired placement. As noted above, taper ties for formwork are traditionally produced by two methods: machining complete from a stock steel material or crimping a steel sleeve onto a continuously threaded steel bar. Each of these known methods compromises in terms of strength, cost to produce, and I or durability. The various taper ties described herein eliminate the strength concerns of prior known machined ties, reduce the cost to produce for either prior known taper tie, and increase mechanical interlocking to improve durability when compared to the prior known ties.

[038] As would be appreciated, ties are used in formwork systems to resolve the lateral forces exerted on the formwork by freshly placed concrete. Various types of tie systems are available. As would be understood, taper ties are one such system in which the conical body of the tie creates a tapered void in the concrete, facilitating removal of the complete tie unit from the wall upon completion of the pour and hardening of the concrete. Taper tie assemblies for use with formwork are traditionally machined from an oversized round steel stock material and are of varied length, possibly necessitating relocating the part in the machine during fabrication. These machined ties made of steel stock are very costly — in terms of both raw materials and time-due to the materials, machinery, and time involved. Additionally, raw materials utilized in these prior known machined steel tie assemblies are often of lesser strength and can suffer from stress concentrations due to their geometry. Further, as would be understood, cut threads are more prone to damage than rolled threads, and small deformations in threads can make a nut inoperable.

[039] Alternative known designs exist in the marketplace, shown for example in FIG. 1 , where a continuous roll threaded rod 2 (also referred to herein as a “threadbar”) is “sleeved” by a tapered machined steel tubular element 4. The tubular element 4 is crimped to the threaded rod 2 to create a singular tie 6. While this type of assembly 6 can be more economical than a machined tie, it can suffer from incomplete mechanical interlocking between the two parts (the rod 2 and tubular element 4), resulting in difficulty removing the tie 6 from a wall and damage to the tie 6. Damage to the tie 6 may cause the tie 6 to need to be discarded, an economic loss.

[040] Other known embodiments of this type of tie 6 design utilize an internal thread for the sleeve 4 and two separate rods 6, threaded from each end. While similar in design, this three-piece embodiment is significantly weaker than the a continuous rod 2 due to the discontinuous rod. Neither of these sleeved tie assemblies 6 are sufficiently durable.

[041] Turning to FIGS. 2-7, disclosed herein are various formwork tie assemblies 10 where a material 16 is molded directly against a threaded rod 12, creating a continuously bonded and / or mechanically interlocked tapered section over the entire length of the overmolded element 16. In various implementations, a threaded rod 12 is overmolded with a suitable material to create a taper tie 10 with overmolded element 16, for use with formwork in concrete construction.

[042] The various implementations described herein use a continuous high-strength threaded rod 12 to carry the structural loads necessary while the overmolded element 16 creates the void in the concrete from which the tie 10 can be removed. As would be understood, one end 18 of the threaded rod 12, a turned end 18, may extend past the threads 14, and may optionally be painted a contrasting color, such as red. This contrasting color may be advantageous because it may increase visibility of the ties 10 amongst the formwork. Further, the contrasting color provides, to a user, an indication as to which end 18 of the tie 10 to strike for removal.

[043] In certain implementations, the overmolded element 16 may also be color coded to provide a visual indication of the length of the tie 10. Being able to quickly determine the length / size of the tie 10 based on the color of the overmolded element 16 is useful for on site and warehouse management because it provides a quick visual indicator of the category the tie 10 belongs in. For example, for each length of tie 10 the color of the overmolded element 16 can differ (e.g. 36” - red, 44” - blue, 52” - yellow).

[044] In certain implementations, the overmolded element 16 tapers gently along its length, decreasing in diameter. In various implementations, the overmolded element 16 includes a further shaped section 20 at each of its ends sloping towards the threaded rod 12.

[045] As would be appreciated, both cold rolled and hot rolled threaded rod 12 profiles are available and commonly used in the industry. The various devices, systems, and methods disclosed herein are optionally implemented with hot rolled rods. [046] The rod 12 for the devices, systems, and methods described herein is oblong in cross section, providing deformed threads 14 on two faces A and flats B on the remaining two faces, shown for example in FIGS. 3 and 4. As can be seen, the outside circumference of the rod 12 is non-circular which provides mechanical interlock between the overmolded element 16 and the rod 12 to prevent the rod 12 from turning out of the tapered overmolded element 16. That is the rod 12 cannot slip or be spun out of the overmolded element 16.

[047] Alternative implementations could be used with cold rolled threaded rods which provide a full helical thread profile. In these alternative implementations, further steps may be taken to bond the overmolded material to the rod. These steps may include application of bonding agents to the metal rod prior to overmolding thereby improving adhesion. In various implementations, the bonding agents include heat sensitive adhesives that are activated by the heat of the overmolding process. These bonding agents / adhesives may optionally be applied in-mold. Alternatively, a second resin suitable for bonding to the substrate may be placed in a separate "shot" in the mold.

[048] In various implementations, the threaded rod may be galvanized. The galvanization can be done by either hot dip galvanizing or electroplating. It would be appreciated in light of this disclosure that the surface roughness of the tapered portion of the taper tie is important for removal of the taper tie from the hardened concrete and as such prior art machined taper ties cannot be hot dip galvanized. Further, known taper ties that include a tapered sleeve are zinc-nickel plated which is a more costly process than zinc electroplating.

[049] Turning to FIGS. 5 and 6, the taper ties 10 disclosed herein are comprised of two different elements — a rod 12 and an overmolded element 16 — each made of a different material and as such can be tailored to be suited for their own demands. That is, both the rod 12 and overmolded element 16 can be adjusted in composition, shape, and size, etc. depending on the purpose to be made of the taper tie 10. For example, large diameter ties 10 are often used for larger structural loads, while small diameter ties 10 may be used when the structural load is not as high, as would be understood. Further, the geometry of the tapered portion — overmolded element 16 — may be varied for different lengths of ties 10 or diameters of openings that the ties 10 are to be inserted into.

[050] FIG. 7 shows a cutaway view of a concrete form 30 with a tie 10 in use. As would be appreciated, the concrete form 30 includes two sides / walls 32 between which concrete 36 is poured. As the concrete 36 is poured and hardening, lateral forces are applied to the sides / walls 32. The lateral forces are countered by ties 10, spanning the space between the sides / walls 32. Nuts 34 are spun unto the threaded rod 12 of the tie 10 to hold the tie 10 in place along the formwork 30. As can be seen the overmolded element 16 is disposed between the sides I walls 32, such that the concrete 36 when poured will surround the overmolded element 16, forming a void in the concrete 36. Once the concrete 36 is hardened the tie 10 can be removed from the formwork 30.

[051] As would be appreciated, taper ties 10 accommodate a range of wall 32 widths and diameters depending upon the load carrying demand from the formwork system. In various implementations, the ties 10 disclosed herein taper from about 7/8” to about 1 -1/16” and utilize an about 15 mm threaded bar 12. Various alternative implementations of the tie use an about 20 mm threaded bar 12 and provide a taper from about 1 -1/8” to about 1 -1/2”. Taper lengths can vary depending upon the desired wall thickness and may generally range from about 15” to about 37” for typical construction. Various alternative dimensions are possible and would be understood by those of skill in the art.

[052] One specific example, the threaded bar 12 is a 5/8” by 36” galvanized bar with a 1/2" diameter not including the threads. Including the threads, the bar 12 has a diameter of about 15 mm from flat B edge to flat B edge, and a diameter of about 16.8 mm from thread A to thread A. In this example the tapered overmolded 16 section is 15 3/16” in length. In this example, the tapered overmolded 16 section tapers from a 1 1/16” diameter to a 7/8” diameter.

[053] In another example, the threaded bar 12 is a 5/8” by 44” galvanized bar. In this example the tapered overmolded section 16 is 23 3/16” in length.

[054] In another example, the threaded bar 12 is a 5/8” by 52” galvanized bar. In this example the tapered overmolded section 16 is 31 3/16" in length.

[055] As would be understood, use of a threaded rod 12 is a lower cost, higher strength solution than machining steel stock. Further, threaded rods 12 may be galvanized to protect against corrosion without concern of hydrogen embrittlement due to lack of stress riser points in the geometry.

[056] As would be understood, for a machined taper tie, it is started with a round bar of the same strength as the rolled threadbar 12 (used in the disclosed ties 10) but of the diameter of the largest part of the taper. The taper and threads are machined (cut) into that stock, and the material removed is waste. With the disclosed ties 10, the threadbar 12 is made by a highly efficient process that takes a rod of diameter slightly larger than the root (smallest threaded diameter) and moves the material to create threads rather than removing material for waste.

[057] Rolled threads are work hardened which increases wear and fatigue resistance along with increased mechanical properties. With a continuous threadbar, no stress concentrations exist at the threaded transition to the tapered body, making bending damage less likely. Ease of removal of the disclosed taper tie is improved over prior art, making damage less likely.

[058] In various implementations, the overmolded element 16 material is non-structural and need not carry any stresses other than those induced by elongation of the rod 12 material under load. The material used in the tapered overmolded element 16 may be lighter in weight and cheaper to produce than starting with a stock round bar, as is done with prior known machined taper ties.

[059] Characteristics of the overmolded element 16 material may be tailored to ease in removal from the concrete. For example, lower friction materials with less surface roughness than machined steel may be used. In various implementations, the material for the overmolded element 16 may be one or more of TPU (thermoplastic urethane), thermoplastic, thermoset plastic, die cast metal alloys, or other appropriate material as would be appreciated by those of skill in the art. In certain specific implementations, the overmolded element 16 is a thermoplastic, which is of a much lower density than steel, resulting in a lower weight assembly than prior known taper ties.

[060] As previously noted, the various taper ties 10 described herein are less costly to produce than known alternative designs and provide a higher strength solution with better mechanical interlock than existing designs.

[061] Further, the disclosed ties 10 have increased durability because if damage to the overmolded element 16 occurs, the overmolded element 16 may be removed and discarded, while usage of the threaded bar 12 may be maintained. Additionally, in various implementations, the overmolded element 16, is made from an elastic, highly durable material that allows for large deformations without negatively impacting the surface of the threaded bar 12.

[062] Although the disclosure has been described with references to various embodiments, persons skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of this disclosure.