Mounting device

Abstract

Fastening device for connecting a first plate-shaped object (22) to a second plate-shaped object (24) on a surface, wherein the first and second plate-shaped objects (22, 24) each have mutually aligned non-circular or angular openings (23, 25) through which a base body (1) of the fastening device can be inserted, wherein the base body (1) has a bearing surface (10) for a screw head (31) of a fastening screw (30), an opening (11) for the passage of a threaded shank (32) of the fastening screw and integrally formed elastic arms (3) which extend from a side of the bearing surface (10) abutting an outer surface of the first plate (23) through the openings (23, 25) of the two plate-shaped objects (22, 24), and with a nut (33) screwed onto the threaded shank (32) between the elastic arms (3),which is movable back and forth along the elastic arms (3) by turning the fastening screw, characterized in that the bearing surface (10) has two elastic arms (3) and two openings (12) arranged on opposite sides of the opening (11) for arms (4) pivotally mounted in the base body (1), which extend between the longitudinal edges of the elastic arms (3), that the nut (33) screwed onto the fastening screw causes the free ends of the arms (4) pivotally mounted in the base body (1) to spread open when the fastening screw (30) is tightened, wherein the nut (33) is secured against rotation relative to the base body (1) by the two elastic arms (3) and the two arms (4) pivotally mounted in the base body (1),and that the articulated arms (4) extending from the support surface (10) have a cross-section that decreases in the radial direction in the longitudinal direction of the fastening device and can be spread apart from each other towards the inner edges of the openings (23, 25) of the plates (22, 24) by moving the nut (33) towards the support surface (10).

Description

[0001] The invention relates to a fastening device of the type mentioned in the preamble of claim 1.

[0002] Such fastening devices enable the connection of two essentially plate-shaped parts or plates which have respective non-circular or angular openings which are aligned with one another. Arm parts or the shaft part of the fastening device can be pushed through the openings, whereby the non-circular or angular shape of the openings and the likewise non-circular or angular shape of the shaft of the fastening device ensure that it is secured against rotation.A support surface of the fastening device rests on the outer surface of the outer plate and connects the arm parts or is connected to the shaft. Spreading of the arms or the outer parts of the shaft of the fastening device is achieved by corresponding spreading elements, which either form part of a rotatable actuating element (DE 202012002687 U1) or are formed by a polygonal nut screwed onto a screw or other threaded element that extends through an opening in the support surface and interacts with inner surfaces of the shaft that taper conically in their cross-section starting from the support surface. Another example of such a fastening device is described in DE 20 2014 101 289 U1. DE 19 65 493 U describes a nut cage for round holes accessible from one side.

[0003] The concept of expanding parts of a fastener when a screw is screwed in is known from expansion anchors, as described, for example, in DE 21 55 054 A or US 3 623 396 A.

[0004] Such fastening devices are widely used for securing front panels of device racks, but are also suitable for other fastening purposes where the opening in the plate-shaped parts is only accessible from one side of the two panels. However, in many cases, they have a complex structure and are not easy to manufacture.

[0005] The invention is based on the object of providing a fastening device which connects two plate-shaped parts to one another, the connecting points of which are only accessible from a main surface of one of the plates, wherein the fastening device has a simple structure and is easily detachable and removable from the plates if necessary.

[0006] Since the objects belonging to the panels may be very heavy, a very stable fastening is desired.

[0007] This object is achieved by the features specified in claim 1. Advantageous embodiments and further developments of the invention emerge from the subclaims.

[0008] The fastening device according to the invention has a base body with a support surface for a screw head of a fastening screw, an opening for the passage of a threaded shank of the fastening screw and molded-on elastic arms which extend from a side of the support surface resting against an outer surface of the first plate through the openings in the plate-shaped objects. A nut screwed onto the threaded shank between the elastic arms (3) can be moved back and forth along the elastic arms by turning the fastening screw. In addition to the two elastic arms, the support surface has two openings arranged on opposite sides of the opening for arms which are articulated in the base body and extend between the longitudinal edges of the elastic arms.When the fastening screw is tightened, the nut screwed onto the fastening screw causes the free ends of the arms, which are articulated in the base body, to spread apart. The nut is secured against rotation relative to the base body by the two elastic arms and the two arms articulated in the base body. Starting from the support surface, the articulated arms have a cross-section that decreases radially in the longitudinal direction of the fastening device and can be spread apart toward the inner edges of the openings in the plates by moving the nut toward the support surface.

[0009] By using arms articulated within the base body, these arms can be made of a different material than the base body itself and exhibit greater hardness than the latter, thus ensuring secure fastening of the plate-shaped objects without making the manufacturing process of the fastening device complicated and costly. The fastening device can also be used even if the fastening point is only accessible from one side, and after loosening the fastening screw, it can be easily pulled out of the openings in the plate-shaped objects and reused.

[0010] The invention is explained in more detail below with reference to embodiments shown in the drawings.

[0011] The drawings show: Fig. 1 an application example for an embodiment of the fastening device according to the invention. Fig. 2 an oblique view of the front of the base body of the embodiment of the fastening device. Fig. 3 a perspective view of the base body of the embodiment of the fastening device according to the Fig. 1 and Fig. 2. Fig. 4 a front view of the base body according to the Fig. 1 to 3. Fig. 5 a side view of the base body according to the Fig. 1 to 4. Fig. 6 an end view of the base body according to the Fig. 1 to 5. Fig. 7A is an end view of an embodiment of the pivotally mounted arm for the embodiments of the fastening device according to the Fig. 1 to 6. Fig. 7B is a side view of the embodiment of the arm according to Fig. 7A. Fig. 7C a top view of the arm after Fig. 7A. Fig. 7D is a perspective view of the arm according to the Fig. 7A to 7C. Fig. 8 a longitudinal sectional view of the embodiment of the fastening device in the non-expanded state. Fig. 9 an end view of the embodiment of the fastening device in the non-expanded state. Fig. 10 a longitudinal sectional view of the embodiment of the fastening device in the spread state. Fig. 11 is an end view of the embodiment of the fastening device in the expanded state.

[0012] In Fig. 1 shows an application example for an embodiment of the fastening device 1 according to the invention, wherein in the upper half of the figure the fastening device 1 is shown after being inserted through openings 23, 25 of two plate-shaped parts or plates 22, 24 to be connected to one another, while in the lower part the fastening device 1 is shown after a nut 33 has been screwed onto a shaft 32 of a fastening screw 30, whereby the plates are fastened to one another, as will be explained in more detail below.

[0013] The embodiment of the fastening device illustrated in the drawings consists of a base body 1, which can be made of plastic or metal. The base body 1 has a support surface 10 with a surrounding reinforcing edge 13 for a head 31 of the fastening screw 30 and an opening 11 for a shaft 32 of the fastening screw 30.

[0014] As is particularly evident from the Fig. 2 to 6, which show the base body, the base body 1 further comprises two molded elastic arms 3 on the underside of the support surface 10, which are arranged set back from the border 13. In the support surface 10, two openings 12 are formed on opposite sides of the opening 11 at right angles to the elastic arms 3, into which two further arms 4 can be releasably inserted, which are articulated relative to the base body 1. The arms 4 are preferably made of metal or other very hard material and, in the initial state, together with the elastic arms, form a substantially rectangular cross-section, the shape and size of which is adapted to the openings 23, 25 of the plates 22, 24, as can be seen in particular from the upper part of the Fig. 1 and Fig. 9 can be seen.

[0015] A preferred embodiment of the articulated arms 4 is shown in the Fig. 7A to 7D. The arms 4 are inserted into the openings 12 and have a pivoting projection 41 which is inserted into the openings 12 surrounding and in particular into the Fig. 2 and Fig. 3 shown recesses 14 of the support surface 10 and is later held in these by the head 31 of the fastening screw 30.

[0016] Furthermore, the arms 4 have, at their end opposite the pivoting projection 41, a run-on bevel 42 for the nut 33, over which the nut 33 runs when screwed onto the shaft 32 and pre-tensions the arms outwards against the edges of the openings 23, 25 of the plates 22, 24.

[0017] The elastic arms 3 can each have an internal, essentially triangular cross-sectional recess 36 for receiving an edge of the nut 33. As the depth of the triangular recesses 36, which serve in particular to prevent rotation, decreases radially from the free end of the arms toward the support surface 10, the arms 3 are also spread open when the nut is screwed onto the shaft 32 and preloaded against the edges of the openings 23, 25 of the plates 22, 24.

[0018] When using the described embodiment, the fastening device 1 is inserted into two metal sheets or plates with corresponding openings 23, 25 for the elastic and articulated arms until the base body rests on one of the metal sheets. The nut 33 is screwed onto the shaft 32 extending through the opening 11, the radial rotation of which is prevented by the elastic arms 3 and the articulated arms 4. The arms 4 are shaped such that the nut 5, when screwed onto the shaft of the screw, can slide on the run-on slope 42 and thereby spread the elastic and articulated arms outwards. When the screw 30 is tightened until the elastic and articulated arms are sufficiently spread, forces can be transmitted via the side walls of the fastening device 1, which can be used, for example, to hold server or switching device modules in computer cabinets.

[0019] To avoid overstretching when spreading the elastic arms, stops can be provided on the base body to prevent this.

[0020] If the screw is loosened again after tightening, the fastening device can be removed again from the corresponding openings 23, 25 in the plates, especially if, in addition to the elastically formed arms, the articulated arms are elastically prestressed towards one another due to the geometry of the base body 1.

Claims

[1] Fastening device for the surface connection of a first plate-shaped object (22) to a second plate-shaped object (24), wherein the first and second plate-shaped objects (22, 24) have respective non-circular or angular openings (23, 25) aligned with one another, through which a base body (1) of the fastening device can be inserted, wherein the base body (1) has a support surface (10) for a screw head (31) of a fastening screw (30), an opening (11) for the passage of a threaded shaft (32) of the fastening screw and integrally formed elastic arms (3) which extend from a side of the support surface (10) lying against an outer surface of the first plate (23) through the openings (23, 25) of the two plate-shaped objects (22, 24), and having a nut (33) screwed onto the threaded shaft (32) between the elastic arms (3),which can be moved back and forth along the elastic arms (3) by turning the fastening screw, characterized bythat the support surface (10) has two elastic arms (3) and two openings (12) arranged on opposite sides of the opening (11) for arms (4) which are pivotally mounted in the base body (1) and extend between the longitudinal edges of the elastic arms (3), that the nut (33) screwed onto the fastening screw causes the free ends of the arms (4) pivotally mounted in the base body (1) to spread apart when the fastening screw (30) is tightened, wherein the nut (33) is secured against rotation relative to the base body (1) by the two elastic arms (3) and the two arms (4) pivotally mounted in the base body (1), and that the pivotally mounted arms (4), starting from the support surface (10), have a cross-section in the radial direction which decreases in the longitudinal direction of the fastening device and, by a movement of the nut (33) towards the support surface (10), are moved away from each other against Inner edges of the openings (23,25) of the plates (22.24) can be spread open., [2] Fastening device according to claim 1, characterized by that the elastic arms (3) each have an internal recess (36) which is substantially triangular in cross-section for receiving an edge of the nut (33). [3] Fastening device according to claim 2, characterized by that the depth of the triangular recess (36) for receiving an edge of the nut (33) increases in the radial direction starting from the support surface (10) in the direction of its free end. [4] Fastening device according to one or more of the preceding claims, characterized by that the cross-section of the elastic arms (3) tapers in the radial direction starting from the support surface (10) towards its free end. [5] Fastening device according to one or more of the preceding claims, characterized bythat the screw head (31) of the fastening screw (9) on the support surface (10) covers the openings (12) for the articulated arms (4). [6] Fastening device according to one or more of the preceding claims, characterized by that the first plate (23) is the front plate of a device that can be inserted into a device frame, and that the second plate (24) is a fastening rail of the device frame for the front plate. [7] Fastening device according to one or more of the preceding claims, characterized by that the base body (1) is made of plastic or metal. [8] Fastening device according to one or more of the preceding claims, characterized by that the articulated arms (4) are made of metal. [9] Fastening device according to one or more of claims 1 to 7, characterized by that the articulated arms (4) are made of hard plastic.

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