Lightweight structural fasteners

Abstract

A lightweight structural fastener (10) includes an integral plastic clip body (20) and a split nut (40). The clip body has the basic shape of a clamp, including two opposed longitudinally extending arms (22, 24) and a cage (28) within which the split nut is floatingly mounted. The split nut in turn has a nut bottom (42) that is substantially designed in the shape of a plate. A body (44) having a top surface (41) and a plurality of side walls (51, 51') extending between the nut bottom and the top surface is mounted on the nut bottom. The side walls of the body preferably have convex ridges, and the cage has correspondingly designed concave walls. The dimensions are set such that when the lightweight structural fastener is used, the convex-concave surface pair serves as a torque support.

Description

Technical Field

[0001] The present invention relates to light - weight structural fasteners, which are known in the industry as clips or, in English terms, clip nuts. In principle, such clips consist of a clamp - like body and a split nut movably mounted thereon. The present invention particularly relates to light - weight structural fasteners having a split nut made entirely of plastic. Background Art

[0002] In the transportation industry (e.g., the aviation industry), light - weight linings are usually employed, which must be detachably fixed. To avoid machining operations during final installation, such linings, for example in the form of plates, are pre - drilled and fitted with clips. Then, during final installation, fasteners for other linings or structural load - bearing members are inserted into their threaded elements. The plate - like parts or components are usually light - weight wall parts or sandwich panels, which, for weight reasons, mostly consist of two outer layers (made of plastic or aluminum) bonded to a honeycomb - like reinforcement located therebetween.

[0003] Prior Art

[0004] Clips are in principle disclosed in the prior art. US 8,177,466 (US2008 / 0310931A1) shows a two - piece clip having a clamp - like elastic body and a split nut mounted in a socket block.

[0005] US 5,423,646 describes a clip having a metal body with a sleeve with an internal thread fixedly mounted on one of its arms.

[0006] EP 0 407 282 A1 shows a clip consisting of a metal hoop with a clamping seat having a split nut with a widened seating base facing the inner region of the clip.

[0007] The common feature of all three clip embodiments is that precautions have been taken to prevent the nut from being driven when the screw is screwed in. US 5,423,646 solves the problem caused by the rigid connection with its fixed threaded sleeve, but the installation process is not very comfortable because the nut is not useful. In the other two documents, the torque or force that occurs is transmitted from the split nut to the body through protrusions, pins or stop surfaces and is then conducted from there into the component fitted with the clip. The torque support is only important when screwing the fastener into the split nut and does not contribute to the actual fixation of the components to each other. The provision of such protrusions, pins or stop surfaces not only increases the complexity of the split nut but also raises the installation cost of the split nut and the body. Summary of the Invention

[0008] The object of the present invention is to reduce the above - mentioned disadvantages of the prior art and, in particular, to provide a clip that can have improved performance related to installation, operation, and manufacturing.

[0009] This task is accomplished by a lightweight structural fastener of a basic two-piece type consisting of a clip body and a split nut.

[0010] The lightweight structural fastener according to the present invention includes a one-piece plastic clip body and a split nut. As in the prior art, the clip body has the basic shape of a clamp, which has two opposing longitudinally extending arms and a connecting edge connecting the two opposing arm ends. Thus, the two opposing faces of the arms and the connecting edge depict or define a receiving space for a plate-like member.

[0011] The term "receiving space" herein shall refer to the volume depicted by the interfaces of the two arms and the connecting edge. In the clip body or the lightweight structural fastener, the terms "inner side" or "inner region" also refer to the inner region between the two arms of the clip body. The terms "upper" and "lower" refer to a common illustration similar to Figure 1 the illustration shown.

[0012] The split nut further has a nut bottom, which is basically designed in a plate shape and has a flat bottom surface pointing towards the inside of the clamp. On the nut bottom (specifically on the side opposite to the bottom surface (upper side)), a body with a top surface and a plurality of side walls extending between the nut bottom and the top surface are mounted.

[0013] Thus, in short, the nut bottom is like a flange with an irregular design, which closes the body at the lower end of the body.

[0014] The body preferably has a substantially polygonal cross-section parallel to the nut bottom. Thus, in a common way of thinking, the horizontal cross-section has an irregular shape preferably in the form of a quadrilateral. According to its function as a split nut, the body has a central hole, which extends through the nut bottom, the body, and the top surface (a vertical through-hole).

[0015] A cage composed of a plurality of wall members is mounted on the first arm of the clip body, and the split nut is floatingly mounted within the cage. The cage refers to a receiving groove or a movable support for the split nut commonly found in a clip. The cage holds the split nut with a clearance. The cage has at least two holding openings for this purpose.

[0016] The second arm of the clip body is designed as a flat support surface in the shape of a tongue with respect to the inside of the clamp. Thus, the support surface refers to the contact surface that contacts the member on which the lightweight structural fastener is sleeved.

[0017] Each of the two arms, specifically the first arm in the cage region and the second arm in the tongue region, has an opening, which is aligned with the central hole of the split nut placed within the cage.

[0018] In addition, the first arm is designed such that the bottom surface of the split nut faces the inner side of the clamp and is designed as a bearing surface for direct contact with the plate-shaped member. In most embodiments of the prior art, the split nut is held as a member on the top side of an arm and is thus pressed onto the arm in the installed state. Therefore, it also serves as a spacer for the split nut. In the present invention, the first arm is designed such that the bottom of the nut forms part of the inner side of the first arm. Ideally, the remaining inner side of the arm is designed such that it is flush with the bottom surface of the nut bottom in a planar manner. Alternatively, it can also be slightly offset in a planar manner so that the bottom surface of the thread bottom can abut against the member in any application scenario.

[0019] In addition, the body of the split nut has at least two pin-shaped protrusions that are inserted into corresponding openings in the wall members of the cage. Preferably, the protrusions are arranged on opposite sides of the body and are dimensioned such that they have a clearance in the respective openings. The protrusions have the main function of preventing loss in cooperation with the openings of the cage and have little torque-bearing effect. The force or torque is first transmitted to the wall members of the cage through the side wall of the body when the fastener is screwed into the central central hole.

[0020] The n side walls of the split nut body are preferably concave bulges, where n => 3. Since the horizontal cross-sectional shape of the body is described as a polygon, a hexagon with, for example, 3 or 4 concave (inward) bulged sides can meet the condition. An octagon with, for example, 4 or 6 concave sides is also possible. It can be explicitly specified that other straight or convex side walls can also be provided between the concave (side) wall surfaces. The wall surfaces can transition continuously with each other or be separated by edges. Cooperation with the wall members of the cage is important.

[0021] Therefore, the lightweight structural fastener according to the present invention has at least n inwardly directed wall members of the cage that bulge inwardly. "Inward" here means towards the area defined by the wall members.

[0022] In a preferred embodiment, the side walls of the split nut body and the wall members of the cage are paired and opposed. In other preferred embodiments, the bulges of the side walls or wall members will be in the shape of a conical section, i.e., can be described as an arc segment, ellipse, parabola, or hyperbola in a horizontal cross-section (parallel to the bottom surface). Structurally, it is preferred to design the bulge as an arc in this case. Therefore, in an embodiment that is preferred in terms of structure and manufacturing technology, the bulge uses the same geometric basic shape. The arc radius can be more preferably selected to be substantially the same for the concave side walls or convex wall members.

[0023] If the above-mentioned features are considered comprehensively, the outer shape of the split nut side wall is complementary to the wall member of the cage, and the outer bulge meets the inner bulge. Therefore, if the fastener is connected to the split nut, the split nut can be reliably driven to rotate to a certain extent by the fastener at the beginning until the rotational movement is blocked. Mounting the split nut floatingly in the cage provides the desired degree of freedom as planned. In the prior art with protrusions and projections as torque supports, they are used for force dissipation. In the present invention, this is achieved through the contact of the side wall / wall member. Here, the contact is automatically adjusted according to the different orientations or positions of the fastener, split nut, and cage. Therefore, the contact surface can be carried out through one or more surfaces simultaneously. Since the contact surface is much larger than the continuous pieces or protrusions in the prior art, a more gentle force dissipation is achieved, which allows for the optimized design of the entire lightweight structural fastener.

[0024] The central central hole of the split nut is equipped with an internal thread in a preferred embodiment. As an alternative and equivalent to the thread, other fastening types can also be specified, such as bayonet joints, quick-clamping positioning, and clip joints.

[0025] It has been shown that the split nut can be integrally made of plastic, preferably a thermoplastic, and especially PEEK. Aggregates such as glass fibers, carbon fibers, or other especially injection-moldable aggregates can be used to adjust the strength of the split nut as desired or required.

[0026] In a special embodiment, the outlet of the thread facing the top surface can be designed to clamp and fix the screwed-in fastener. The methods known in the prior art can be used here, for example, by slightly widening the thread ridge, changing the pitch, or having an incompletely formed thread. Alternatively or additionally, it can also be considered to apply a coating, glue, or other material layer to the thread outlet to increase the resistance inside the thread end and thus fix the thread connection. It has been shown that forming a thread in plastic can be successfully achieved by selecting the appropriate strength.

[0027] In another embodiment, the bottom of the nut can be designed such that it has a placement area on its top side facing away from the bottom surface. The placement area has concave bulges and is oriented in such a way that they allow the split nut to roll or tilt along the first arm. As already explained, the protrusions mounted in the corresponding opening of the cage on the main body first serve as an anti-loss mechanism. The raised top side of the nut bottom or the placement surface on the top side faces the bottom side of the cage or the first arm due to the flange-like overhang of the main body. As described above, the bottom surface forms a direct placement surface for the member to be fixed because the cage is always consistently placed on the raised top side of the nut bottom or the placement surface on the top side. Due to the selected shape (semicircular bulge), an additional possibility of tilting movement appears between the first arm / cage bottom side and the split nut.

[0028] Alternatively, a bevel can be provided at the bottom of the nut relative to the bottom surface of the instrument. It is preferably arranged on the side of the split nut facing away from the connecting edge and supports or simplifies the movement of the lightweight structural fastener onto the component.

[0029] It can also be provided that the bottom of the nut has a stop edge at the edge opposite to the bevel. Thus, when the split nut is installed in the cage (in other words, correctly installed), an emergency support surface is formed that is parallel and spaced apart from the mating surface on the clamping body.

[0030] Similar to the split nut, the clamping body can be integrally made of plastic, preferably a thermoplastic, especially PEEK. After it is designated as the clamp, the clamping body is preferably integrally designed as a two-component injection molding, where the first plastic component is selected to have greater elasticity than the second component. The adjustment of the strength or elasticity of the plastic components can be achieved in a known manner by means of fillers such as glass fibers or carbon fibers.

[0031] The more elastic component is preferably mainly used in the area of the second arm or tongue or the area of the connecting edge. Thus, it is easy to slide onto the component because the tongue and the connecting edge elastically support the installation process in a bent manner. While the cage, for example, can be made of glass-filled PEEK in one embodiment to obtain a more rigid structure. Description of the Drawings

[0032] Now, the present invention will be explained by way of example with reference to the drawings and in connection with particularly preferred embodiments.

[0033] Figure 1 A perspective view of the lightweight structural fastener of the present invention is shown.

[0034] Figure 2 The clamping body is schematically shown from above without the split nut.

[0035] Figure 3 The clamping body is schematically shown from the side without the split nut.

[0036] Figure 4 A perspective view of the split nut is shown.

[0037] Figure 5 A side view of the split nut is shown.

[0038] Figure 6 A view of the split nut is shown from above. Detailed Description of the Invention

[0039] Figure 1The light structural fastener 10 is shown in a perspective view from above and to the side. The two main components are the split nut 40 mounted within the cage 28, which forms the major part of the first arm 22 of the clamping body 20. The first arm 22 is connected to the second arm 24 by the connecting edge 23, which is functionally designed as (and referred to as) the tongue 27. The designations of the first arm 22, the second arm 24, and the connecting edge 23 for connection are mainly based on their functions. Since the clamping body 20 is of an integral design and the functional areas intersect each other, clear and accurate boundary lines are neither meaningful nor required for a person skilled in the art.

[0040] Figure 1 Other details are also shown, which can be defined in mass production from a structural perspective, such as notches for material saving, ribs, and gripping surfaces.

[0041] In Figure 2 a top view of the clamping body 20 (i.e., the first arm 22) of the light structural fastener 10 looking "from above" is shown. The structure of the cage 28 can be seen from above. The wall elements 31, 31'... 31"' are visible as surfaces that bulge inwardly in a convex shape towards the inner region of the cage. The cage has a large opening 29 through the first arm 22, which allows a part of the second arm 24 or the tongue 27 to be seen. The tongue 27 has another opening 25. The connecting edge 23 is shown in the top view. Two regions of the cage 28 have openings 36, 37 within the cage 28, which are shown in dashed lines opposite each other on the longitudinal axis of the first arm 22. These openings are arranged parallel to the extension plane of the first arm 22.

[0042] Figure 3 A side view of the clamping body 20 is shown, which still has the first arm 22, the second arm 24, and the connecting edge 23 for connection. The cage 28 occupies the major part of the first arm 22. Between the cage 28 and the transition region to the connecting edge 23, this arm is provided with a stepped portion oriented towards the inner side of the clamp, which provides an emergency support surface 19. Figure 1 The cooperation of the emergency support surface 19 and the stop edge 49 is shown (see also Figure 6 ). The positions of the opening 25 in the second arm 24 and the opening 29 (in the first arm 22) are indicated by arrows. The cut sleeve portion 21 that surrounds the opening 25 in the region of the tongue 27 is similar to a collar. It is used to center the light structural fastener on the opening of a component (not shown here). The bevel of the inlet opening to the receiving space 26 makes it easy to move the light structural fastener onto the component.

[0043] Figure 4The split nut 40 is shown in a perspective view in the form of a simplified part. Its main components are the nut bottom 42 and the body 44. The nut bottom 42 is a plate-shaped bottom surface 43 that is substantially flat and has an irregular edge as shown. The flat bottom surface 43 (bottom side) transitions to the aforementioned bevel 45 at one edge. The body 44 is shown as a substantially polygonal body, and its side walls 51, 51', 51"... are concave and are interrupted by planar wall portions. The side wall portions transition to the bevel, which in turn leads to the top surface 41. A central central hole 46 together with its internal thread 49 is shown in the top surface. Two protrusions or bosses 56, 57 are mounted on the body, and they serve as an anti-loss mechanism (after being installed in the clamp body). They are located within the openings 36, 37 in the installed state.

[0044] Figure 5 The split nut 40 is shown in a side schematic view. Here, it can be seen that the nut bottom 42 has a flat bottom surface 43 (bottom side), and its top side has a convex bulge.

[0045] Figure 6 The split nut is also shown in a top view from the top surface 41. It can be seen that the shape of the nut bottom 42 is selected to be irregular here. As seen in the overview Figure 1 and Figure 6 when viewed, there is a contact area between the nut bottom and the bottom side of the first arm 22 of the clamp body 20 facing the receiving space 26. The placement areas 47 and 48 are Figure 6 shown hatched. As also described earlier, since the nut bottom 42 has a convexly bulged surface, the split nut 40 can roll relative to the clamp body in the placement area. The mark 49 indicates a stop edge, which can interact with the emergency support surface 19 in the assembled state.

[0046] The inventive features disclosed in the above description, drawings, and claims are important for implementing the present invention not only individually but also in any technically meaningful or advantageous combination. Figures 1 to 6 The illustrated embodiment is a preferred implementation for the said invention. Other designs of the external shape as described in the claims and their technical equivalents are all covered.

Claims

1. A light-duty structural fastener having an integral clip body made of plastic, - Among them, The clip body has the basic shape of a clamp, and the clip body includes - two opposed longitudinally extending arms - and a connecting edge connecting the ends of the two opposed arms; - Further includes an accommodation space for a plate-like member between the arms, the accommodation space being bounded by the connecting edge on one side; Also has a split nut, - The split nut has a nut bottom which is designed to be substantially plate-like and has a flat bottom surface pointing towards the inner side of the clamp; - And a body which is mounted on the nut bottom and has a top surface and a plurality of side walls extending between the nut bottom and the top surface; - Wherein, the body has a substantially polygonal cross-section parallel to the nut bottom; - And the body has a central hole which extends through the nut bottom, the body and the top surface; Wherein, - The first arm of the clip body has a cage composed of a plurality of wall members, and the split nut is floatingly mounted in the cage; - The cage has at least two retaining openings, - The second arm is designed as a tongue relative to the inner side of the clamp, that is, a tongue-shaped flat support surface, - The first arm in the area of the cage and the second arm in the area of the tongue respectively have an opening which is aligned with the central hole of the split nut placed in the cage, Characterized in that, - The first arm is designed such that the bottom surface of the split nut faces the inner side of the clamp and is designed as a support surface for direct contact with the plate-like member; - The body of the split nut has at least two pin-like protrusions inserted into the retaining openings of the wall members of the cage.

2. The light-structured fastener according to claim 1, characterized in that, The n side walls of the split nut body are concave bulges, where n≥3.

3. The light structural fastener according to claim 1 or 2, characterized in that, At least n inwardly pointing wall members of the cage are convexly bulged inwardly.

4. The light structural fastener according to claim 1, characterized in that, The side walls of the split nut body and the wall members of the cage are opposed in pairs.

5. The light structural fastener according to claim 2, characterized in that, The bulges of the side walls or the wall members follow a conical section, that is, they can be depicted as an arc segment, an ellipse, a parabola or a hyperbola in a horizontal cross-section.

6. The light structure fastener according to claim 2, characterized in that, The bulges of the side walls or the wall members are designed as arcs.

7. The light structural fastener according to claim 6, characterized in that, The radius of the arc is selected to be substantially the same size for the concave side walls or the convex wall members.

8. The light structural fastener according to claim 1, characterized in that The central hole of the split nut has an internal thread.

9. The lightweight structural fastener according to claim 8, characterized in that, The split nut is made of plastic in one piece.

10. The light structural fastener according to claim 8 or 9, characterized in that, The outlet of the internal thread towards the top surface is designed to clamp and fix the screwed-in fastener.

11. The light structural fastener according to claim 1, characterized in that, The nut bottom has a plurality of placement areas on its top side facing away from the bottom surface, the placement areas having concave bulges and being oriented such that they allow the split nut to roll or tilt along the first arm.

12. The light structural fastener according to claim 1, characterized in that, The nut bottom has an inclined hypotenuse relative to the bottom surface.

13. The light structural fastener according to claim 12, characterized in that, The nut bottom has a stop edge at the edge opposed to the hypotenuse, and the stop edge is parallel and spaced apart from the emergency support surface when the split nut is installed in the cage.

14. The light structural fastener according to claim 1, characterized in that, The clip body is made of plastic in one piece.

15. The light structural fastener according to claim 1, characterized in that, The clip body is designed as an integrally molded two-component injection molding, wherein the first plastic component is selected to have higher elasticity than the second plastic component.

16. The light structural fastener according to claim 15, characterized in that, The more elastic component is mainly applied in the region of the second arm or the tongue and the region of the connecting edge.

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