Multi-head bolt and fastener system

A multi-head bolt having a bolt shaft defining a longitudinal axis of the multi-head bolt and a multi-head disposed at a first end of the bolt shaft, the multi-head having at least three pawls, each pawl having a fixed radial orientation relative to the bolt shaft and having a primary plane being aligned with the longitudinal axis of the bolt shaft and having a support surface.

FIELD OF THE INVENTION

The present invention relates to a multi-head bolt used as a quick-access-blind-fastener and further to a fastener system including the bolt. In particular, the present invention relates to a fastener system used to connect and align two objects to each other, wherein the fastening action requires access from only one side of the objects. The present invention also provides a method for such aligning and connecting.

BACKGROUND OF THE INVENTION

Certain fasteners of the prior art generally require access from both sides of the members and the use of two tools—and which is not convenient in certain configurations. In addition, there are known fasteners which, whilst allowing an assembly from one side of the junction only, also draw the members together, being easily removable and re-usable, which can be provided as one assembly and which can be used from either side of the junction. A special configuration of such fastener is also known as a hammer-head bolt, as it shown for example in documents GB 2,239,686 A, FR 2,429,885 A1, CN 109518965 A, DE 21 2017 000 250 U1 or U.S. Pat. No. 5,076,748 A. However, the known bolt configuration is inconvenient in view of absorbing shear forces, tensile forces or traction forces that can arise between the panels. In case of the occurrence of lateral shear forces in-between the panels there is always inherently a force component that acts laterally onto the longitudinal axis of the fastener bolt itself what leads to a misalignment of the fastener.

SUMMARY OF THE INVENTION

The present application provides provide a bolt and a fastener system being improved over the prior art insofar as being able to better divert shearing forces and/or tensile and/or traction forces. At least, the invention shall provide an improved method for an alignment and connection of such objects.

One aspect of the disclose provides a multi-head bolt, comprising a bolt shaft defining a longitudinal axis of the multi-head bolt; a multi-head disposed at a first end of the bolt shaft, the multi-head comprising at least three pawls, each pawl having a fixed radial orientation relative to the bolt shaft and having a primary plane being aligned with the longitudinal axis of the bolt shaft and having a support surface.

In one example, the primary plane for each pawl is parallel to two opposing lateral sides of each respective pawl.

In one example, each pawl has an angled side that intersects the primary plane and wherein a radial distance of the angled side relative to bolt shaft linearly decreases as measured from the support surface to the first end of the bolt.

In one example, the pawls extend from the bolt shaft in a star-shape configuration symmetrically relative to an outer circumference of the bolt shaft.

In one example, at least one pawl is in the form of a fin.

In one example, the support surface extends perpendicularly to the longitudinal axis of the bolt shaft, projecting therewith radially from the bolt shaft's outer circumference.

In one example, at least one pawl is fin-shaped such that the primary plane lies on the longitudinal axis of the bolt shaft and the support surface is perpendicular to the primary plane.

In one example, a width of at least one pawl is smaller than a diameter of the bolt shaft.

In one example, the width of the at least one pawl is at least 15% of a diameter of the bolt shaft and at maximum 65% of the diameter of the bolt shaft.

In one example, the width of the at least one pawl is at least 25% of a diameter of the bolt shaft and at maximum 40% of the diameter of the bolt shaft.

In one example, the width of the at least one pawl is about 33% of the diameter of the bolt shaft.

In one example, a width defined between the two lateral sides of the at least one pawl is substantially constant along the longitudinal axis.

In one example, the bolt shaft defines a cone shape at the first end of the bolt shaft.

In one example, at least a portion of the angled side is coplanar plane to the cone shape of the first end of the bolt shaft.

In one example, the bolt shaft defines has a cone end at an opposite end relative to the multi-head to facilitate insertion of a nut.

In one example, the multi-head bolt further comprises a tension-rod-shank fixed to an end of the bolt shaft opposing the multi-head, on which shank a nut can be screwed.

In one example, the at least three pawls comprises four pawls.

In one example, the bolt shaft defines a hole extending through the bolt shaft at an opposite end relative to the multi-head a for securing a safety split pin.

Another aspect of the disclosure provides a fastener system for connecting and aligning elements together, the system comprising: a multi-head bolt for fastening and aligning the elements, the bolt comprising a bolt shaft defining a longitudinal axis of the multi-head bolt, a multi-head disposed at a first end of the bolt shaft and comprising a plurality of pawls each arranged in a fixed radial orientation relative to the bolt shaft and each having a primary plane being aligned with the longitudinal axis of the bolt shaft and having a support surface; and the plurality of elements each defining an opening extending therethrough, the opening having a shape corresponding to a cross-section profile of the multi-head of the bolt through which opening the multi-head pawls pass.

In one example, the fastener system further comprises a fastening element configured to connect the elements in a fixed manner.

In one example, the multi-head bolt has an external thread and the fastener element comprises a nut having a female thread fitting onto the external thread of the bolt.

In one example, the opening defines cut-outs in a plane direction of the element corresponding to a number and dimension of the plurality of pawls.

In one example, at least one pawl is fin-shaped and has a width that is smaller than a diameter of the bolt shaft.

In one example, the width of the at least one pawl is at least 15% of a diameter of the bolt shaft and at maximum 65% of the diameter of the bolt shaft.

In one example, the width of the at least one pawl is at least 25% of a diameter of the bolt shaft and at maximum 40% of the diameter of the bolt shaft.

In one example, the width of the at least one pawl is about 33% of the diameter of the bolt shaft.

In one example, a width defined between two lateral sides of the at least one pawl is substantially constant along the longitudinal axis.

In one example, the bolt shaft defines a cone shape at the first end of the bolt shaft.

In one example, each pawl has an angled side that intersects the primary plane and wherein a radial distance of the angled side relative to bolt shaft linearly decreases as measured from the support surface to the first end of the bolt.

In one example, at least a portion of the angled side is coplanar to a cone-shaped portion of the first end of the bolt shaft.

In one example, the bolt shaft defines has a cone end at an opposite end relative to the multi-head to facilitate insertion of a nut.

In one example, the elements comprise anti-twist-structures in an element surface being adjacent to the openings, in or at which anti-twist-structure a pawl can rest, respectively, after having rotated the bolt around the longitudinal axis and having inserted the bolt through the opening.

In one example, the anti-twist structure is a recess in which the pawl can rest, such that when resting in the recess rotational movement of the pawl is prevented when the recess receives the support surface of the pawl.

In one example, the element comprises at least one twist-stop protruding from a surface of at least one of the elements and preventing rotation of the multi-head bolt around the longitudinal axis after having inserted the bolt through the opening.

In one example, the twist-stop comprises an abutting surface against which a lateral side of the pawl abuts when being inserted and having turned the bolt until abutting the abutting surface.

In one example, the fastener system comprises a separate plate in which an anti-twist-structure is incorporated and/or at least one twist-stop protruding from the plate is provided, in which plate is to be arranged between the head of the multi-head bolt and an element surface.

In one example, a number of anti-twist structures and/or a number of twist-stop(s) is less or at least equal to the number of pawls.

In one example, the pawls are branched off from the bolt shaft in a star-shaped configuration that is essentially symmetrical around an outer circumference of the bolt shaft.

In one example, the support surface extends essentially perpendicularly to the longitudinal axis of the bolt shaft projecting therewith radially from an outer circumference of the bolt shaft.

In one example, the opening is located in a frame of the element.

In one example, the elements comprises at least one of a formwork panel or a formwork element.

Another aspect of the disclosure provides a method of aligning and connecting at least two elements together, comprising: inserting a multi-head bolt through respective openings of a plurality of panels such that a plurality of pawls with a fixed radial orientation relative to the multi-head bolt align with a plurality of cut-outs of the plurality of panels; rotating the multi-head bolt relative to the plurality panels such that the pawls are out of alignment with the plurality of cutouts such that the plurality of panels are secured relative to the multi-head bolt.

In one example, rotating the multi-head bolt comprises rotating the multi-head bolt and retracting the bolt in an opposite direction of an insertion direction until a support surface of the pawls abuts against a surface of one of the elements.

In one example, the method further comprises fastening the bolt relative to the elements with a fastening element.

DETAILED DESCRIPTION

FIG.1Ais a perspective view of a multi-head bolt10according to one or more aspects of the disclosure andFIG.1Bis a perspective view of the multi-head bolt10ofFIG.1Aengaged with a nut38according to one or more aspects of the disclosure.

As shown inFIG.1A, the multi-head bolt10(also referred to as bolt10) has a longitudinal shaft12having a multi-head16at one end thereof. At least a portion of the longitudinal shaft12can be cylindrical or substantially cylindrical and can define a diameter. The longitudinal shaft12can include external threading for engaging with a nut, as described in detail below. In one example, the longitudinal shaft12can define a longitudinal axis14that is co-axial or substantially co-axial relative to the longitudinal shaft and the longitudinal shaft can define an outer circumference.

The multi-head16has a plurality of pawls18that extend radially from the longitudinal axis14defined by the longitudinal shaft12. In the example ofFIG.1A, the multi-head16of the bolt10includes four pawls18that are arranged radially and symmetrically with respect to longitudinal axis14and can be arranged in a symmetrical star-shaped configuration around an outer circumference of the shaft12. In other examples, the bolt10can include greater or fewer pawls18and can be arranged radially, symmetrically and/or arbitrarily with respect to longitudinal axis14. For example, the multi-head16can include at least or exactly three pawls18that can be arranged arbitrarily or radially and symmetrically with respect to longitudinal axis14. In another example, the multi-head16can include at least or exactly five pawls18that can be arranged arbitrarily or radially and symmetrically with respect to longitudinal axis14.

Each of the pawls18can be unitarily and rigidly formed with respect to the longitudinal shaft12of the bolt10such that each of the pawls18has a fixed radial orientation with respect to the longitudinal axis. In this regard, the pawls18can be inelastic and immovable relative to the longitudinal shaft12of the bolt10. The pawls18can be generally fin-shaped and can be defined by a support surface20, lateral sides18a, and angled side18b. The lateral sides18aof each respective pawl18can be parallel to one another and can be parallel to a plane extending radially with respect to longitudinal axis14. The lateral sides18acan extend between the support surface20, the angled side18b, and the longitudinal shaft12. The support surface20can be perpendicular to the lateral sides18aand can extend along a plane that is perpendicular to the longitudinal axis14.

The angled side18bcan extend from a cone-shaped portion22to the support surface20. In some examples, the angled side18bcan extend as a continuous surface from the cone-shaped portion22to the support surface20, while in other examples there can be a flat portion18cbetween the angled side18band support surface20. The angled side18bcan be coplanar with a cone-shaped portion22and can form a continuous, uninterrupted surface with the cone-shaped portion22and a plane coinciding with the angled side18bcan form an angle with the longitudinal axis14. In one example, the angle can be an acute angle between 5 and 50 degrees and in another example, the angle can be about 45 degrees. While a cone-shaped portion22is depicted, it is contemplated that the portion22can be a truncated cone shape in other examples.

The lateral sides18acan be parallel to each other and can both be parallel with a plane extending radially with respect to the longitudinal axis14. In this regard, the lateral sides can be perpendicular to the support surface20. By virtue of the configuration, a radial distance of angled side18brelative to shaft12linearly decreases as measured from support surface20toward cone-shaped portion22.

At an opposing end of the longitudinal shaft12relative to the cone-shaped portion22is a cone end24that defines a hole28therethrough. The hole28allows the bolt10to be secured by a safety split pin to one or more formwork panels or formwork elements. The cone end24facilitates the threading of nut38onto the longitudinal shaft.

As shown inFIG.1B, the bolt10can be engaged with the nut38to facilitate engagement with formwork elements (for example one or more beams) and/or formwork panels and/or any pair of elements that can connected, as will be described in greater detail below. The nut38can have a female thread and can have wings to enable hand-tightening.

A width of the pawls18, e.g., a distance between opposing lateral sides18a, is depicted as a width b inFIG.1B. The width can be measured at any portion of the pawl, and in one example the width can be measured at or near the support surface20. In one example, the width of pawls18is less than a diameter of the shaft12. In one particular example, the width can be at least 15% of the shaft diameter and at most 65% of the diameter of the shaft. In another example, the width can be in the range of 25% to 40% of the shaft diameter. In yet another example, the width b is approximately 33% of a diameter of the longitudinal shaft12. In these examples, the diameter of the shaft12is measured at a middle portion of the shaft, e.g., a portion that is disposed between the panels32when secured thereto. In one example, a width of the pawl can be substantially constant along the longitudinal axis. A width of the pawl influences the load bearing capacity of the bolt in such a way that, the greater the width the greater the load-bearing capacity with respect to higher tensile force. The width also influences load-bearing capacity with respect to transverse force in an inverse manner, e.g. increasing width reduces load-bearing capacity with respect to transverse force. Above a certain width, almost no additional traverse force can be absorbed.

In one example, an extension shank50is disposed at the end of the shaft opposing the multi-head16. By way of the extension shank50, the shaft can be equipped with a tension rod. In another example, the end part of the shaft12the multi-head bolt10can be equipped with a tension rod. The shank50can have an external thread50aon which a nut50bcan be screwed or the shank50can be in the form of an anchor that is to be fixed in the concrete. Such shank50is commercially available from DYWIDAG® known under the corresponding trademark DYWIDAG®-extension.

Each of the pawls18can define a primary plane associated therewith, the primary plane being defined as parallel to each of the lateral sides18aand extending through the pawl18such that the longitudinal axis14lies on the primary plane. In the example of a four-pawl configuration, the primary plane of a pawl and its opposing pawl are co-planar. In this regard, the primary plane of the pawl18can be defined intersecting with the support surface20and angled edge18bsuch that the longitudinal axis14lies upon the primary plane.

FIG.2Ais a perspective view of a multi-head bolt10engaged with a plurality of plates32according to one or more aspects of the disclosure andFIG.2Bis a perspective view of plate32having recesses according to one or more aspects of the disclosure.

Each of the plates32can engage with formwork panels or formwork elements, or in another example can be integrally formed with the formwork panel or formwork element, for example by welding or the like. Each of the plates32(e.g., a frame of the plate32) define respective an opening32afor receiving the bolt10, with the opening32acorresponding to an outer diameter of the longitudinal shaft12. The opening32aof the plates32can define cut-outs34shaped to receive the pawls18and to allow the pawls18to pass through the opening32a. In this regard, the cut-outs34are positioned to correspond to radial positions of the pawls18and the number of cut-outs34corresponds to the number of pawls18. For example, in the example of three pawls18, the panel32defines three cut-outs34.

The plates32can also define recesses36(e.g., anti-twist structures) that are circumferentially adjacent to the cut-outs34. In this regard, the recesses36do not extend an entire thickness of the plates32and have a thickness that is less than the overall thickness of the plate32. This thickness arrangement creates a space to receive the pawls18, and in one example, the support surfaces20, to ensure a locking arrangement, which will be explained in greater detail below. In one example, the recesses36can define chamfered edges to provide easier movement and insertion of the pawls18relative to the opening32aand recesses36. In one example, the recesses36can define a stepped design along a thickness direction of the plate32corresponding to a shape of the pawls16. The plates32can also include stoppers30(e.g., twist-stop(s)) protruding from a surface of the plate32and extending above a surface of the plates32arranged circumferentially adjacent to the recesses36to prevent rotation of the bolt10and pawls18beyond a locking position and to prevent the respective pawls18from aligning with a cut-out34different from the cut-out through which it was advanced. In this regard, rotation of the pawls18and the multi-head can be prevent or limited when a lateral side18a(e.g., an abutting surface or any other surface of the pawl) abuts against an abutting surface of the stopper30. The number of stoppers30(e.g., twist-stop(s)) can be less than or at least equal to the number of pawls.

This provides a stable configuration for diverting a shear force and/or tension force from the bolt10to the plate32. In the example of a star-like arrangement of the at least three pawls around the bolt shaft, any shear force is diverted in the plane of the panel irrespective from which direction it is caused. This provides a positive high clamp load and, in particular by virtue of the at least three pawls a high capability to absorb sheer loads and/or tensions loads aiding therewith to divert any shear force and/or tension force into those objects as fastened by the system, e.g., onto the panel's surface

FIGS.3A-Ddepict various stages of connecting a plurality of plates32with a multi-head bolt10according to one or more aspects of the disclosure.

As shown inFIG.3A, the bolt10is inserted into both of the respective openings32adefined by the plates32. In this regard, each of the pawls18of the multi-head16are aligned with the corresponding cut-outs34of the plates32, allowing the pawls18and the bolt10to pass through the openings32a.

By virtue of the relationship between cone-shaped portion22and angled edge18b, the bolt10can be easily inserted through the openings32aof the plates32. Further, if the plates32are slightly out of alignment, the bolt10and the cone-shaped portion22and pawls18provide a centering function between the plates32. For example, if the plates32are slightly out of alignment, pushing the bolt10with truncated cone22will automatically orient the plates32such that the openings32aare aligned since the bolt10can only pass through the openings32aand the pawls18can only pass through the cut-outs34when they are in alignment.

As shown inFIG.3B, the bolt10has been inserted into both plates32and will be rotated according to the directional arrow. The pawls18having previously been aligned with cut-outs34will rotate out of position with cut-outs34and the support surfaces20of the pawls will engage with a face of the plate32(or within recesses36, for example by retracting the bolt in a direction opposite of the insertion direction and allowing the pawls to rest and engage within the space defined by the recesses and preventing further rotation).

As shown inFIG.3C, the bolt has been rotated (e.g., by 45 degrees or a geometric multiple) and the pawls18are 45 degrees out of alignment with the cut-outs34, thereby preventing the bolt10from being removed from the plates32without additional rotation. In one example, the rotation of the pawls can be ceased or limited by one or more stoppers30.

As shown inFIG.3D, the plates32are aligned and engaged with one another by virtue of the bolt10. A nut38(and optional washer) can be threaded onto the bolt10to secure the plates32relative to one another.

FIGS.4A-Edepict examples of multi-head bolt geometries according to one or more aspects of the disclosure. As shown, the multi-head of the bolt can be a triangle, a three-pawl, four-pawl, or five-pawl arrangement. Various multi-head configurations are their corresponding openings and cut-outs in an exemplary plate are depicted inFIG.4A.

FIG.4Bdepicts a five-pawl configuration in which five pawls are arranged symmetrically with respect to bolt shaft. In this regard, there is approximately 72 degrees between each of the pawls. With this multi-head, the plate can be configured with an opening that defines five cut-outs, five recesses, and five stoppers.

FIG.4Cdepicts a four-pawl configuration in which four pawls are arranged symmetrically with respect to bolt shaft. In this regard, there is approximately 90 degrees between each of the pawls. With this multi-head, the plate can be configured with an opening that defines four cut-outs, four recesses, and four stoppers. In this example, each of the pawls can be diametrically opposed to a respective pawl. In this regard, each pawl can have an oppositely oriented pawl disposed 180 degrees therefrom.

Since the design of pawls as extending from the shaft simultaneously define and dictate the negative profile in an opening of the plate to push the bolt through, meaning the cut-outs for the pawls that extend from the cut-out for the circumference of the shaft, in one example the number of pawls is advantageously four. This allows for a configuration that each pawl namely decreases the support area on the surface of the plate on which the pawl can rest on after fastening the bolt—which is also dependent from the width of a pawl.

FIG.4Ddepicts a three-pawl configuration in which three pawls are arranged symmetrically with respect to bolt shaft. In this regard, there is approximately 120 degrees between each of the pawls. With this multi-head, the plate can be configured with an opening that defines three cut-outs, three recesses, and three stoppers. Such a three-pawl configuration provides a well-balanced force distribution in the horizontal plane on the panel's surface in any direction around 360°.

FIG.4Edepicts a multi-head having a triangular cross-section, with each corner defining a pawl and thus a three-pawl configuration. With this multi-head, the plate can be configured with an opening that defines three cut-outs, three recesses, and three stoppers.

The foregoing has been a detailed description of illustrative embodiments of the invention. Various modifications and additions can be made without departing from the spirit and scope of this invention. Features of each of the various embodiments described above may be combined with features of other described embodiments as appropriate in order to provide a multiplicity of feature combinations in associated new embodiments. Furthermore, while the foregoing describes a number of separate embodiments of the apparatus and method of the present invention, what has been described herein is merely illustrative of the application of the principles of the present invention. Accordingly, this description is meant to be taken only by way of example, and not to otherwise limit the scope of this invention.