FR3109613A1 - Tamper-proof nut pre-set to the correct tightening torque. - Google Patents

Abstract

A “fusible nut” nut, incorporating a mechanical device making it possible to tighten it to a predetermined torque without a torque wrench and at the same time make it non-removable after tightening. It is made up of four parts: the main body N ° 1 allowing tightening using a tool, the central body N ° 2 forming the tapping, the breakable key N ° 3 forming the part called "fuse", the trapping part N ° 4 allowing the correct assembly of the three other parts designated previously. The set for tightening the nut without a torque wrench and making it tamper-proof. The device according to the invention is intended for all assembly needs of parts bringing together two needs in one, correct tightening at the right torque and safety needs (avoid disassembly of the nut due to possible vandalism, times this one tight). Figure for the abstract: FIG 1

Description

Tamper-proof nut pre-adjusted to the correct tightening torque.

The present invention relates to a particular form of a standardized nut, including two advantages over a single and simple mechanical device placed inside the nut, in order to correctly tighten this nut to the right torque (without the presence of a torque wrench), and also make once tight, the nut free and rotating in both directions, to avoid disassembly of it, therefore inviolable.

The current nuts, all materials combined (stainless steel, steel, synthetic materials, etc.), which are used in many industrial manufactures (Aeronautics, Automobiles, Railways, various Pharmaceutical, Food, Cosmetics industries, etc.), often need to be tightened using a torque wrench to respect a tightening torque. In addition, some of the elements of a machine must never be dismantled. Current nuts are not independent in terms of tightening torques and moreover, many of them can also be removed very easily, even those said to be “unremovable” due to the shape of their heads. It is still despite these precautions, very easy to use vice grips to unscrew them.

The device of this invention overcomes all these drawbacks. Knowing if you are tightening to the right torque and moreover becomes a security element against theft or vandalism. The nut is made up of four parts that are distinctly adjusted and interlocked with each other, with a breakable part called a “fuse” (part inserted into a sharp-edged groove). The nut has a so-called "fuse" part, which allows, depending on an intermediate part calibrated for a desired torque, to tighten an element to a well-defined torque on a threaded rod or a bolt, not oxidized. In addition, once this torque is reached, the "fuse" device breaks, and also allows at the same time to release the hexagonal nut head, so that it becomes unremovable.

The accompanying drawings illustrate the invention:

There represents the nut, in SS section on the lower part and from the outside on the upper part.

There represents the nut according to section AA.

There represents the nut according to the exterior right view (E).

There represents the nut according to the exterior left view (F).

There represents part N°1 alone and in section, with part N°3.

There represents part N°2 alone and in section.

There represents the nut according to the BB cut.

With reference to these drawings, the main steps to design and use this nut using the 4 parts are:

1/ insert at ¾ into the bore of the nut body part N°1, the cylindrical part N°2, forming in its center the tapping of the nut while leaving visible the pre-machined groove provided for the housing of a circlip N°4, (on this subject, any other possible systems of imprisonment of the parts N°1, N°2 and N°3/3'' is possible).

In this specific case, a circlip was chosen for a good understanding of the device.

2/ Match face to face by simple rotation, the lateral grooves of parts N°1 and N°2, then insert the key part N°3 maximum torque or N°3''minimum torque (pre-calibrated according to the torque desired) called "fuse" in the formed and sharp groove provided for this purpose.

3/ put circlips No. 4 in place in its groove, reference H and hold it closed, then finish pushing part No. 2 as well as the circlips into the bore of the body part No. 1, to come to the bottom of stopper (P).

(The circlip fits* automatically in its groove reference J of part N°1).

*This action makes it possible to imprison pieces N°2 and N° 3 or N°3’’ in piece N°1.

4/ Screw the nut to tighten a part.

5/ Tighten until key N°3 or N°3'' called “fuse” breaks in its center, indicating that the correct tightening torque has been reached.

(Note: the shape, the length, the material of this part N°3 (maxi) or 3''(minimum), will determine the breaking torque limit of the said "fuse", and it will be expressed in Newtons per meter. The value of the torque can be determined by laboratory tests and measurements. A simple color identification of the part can also be envisaged according to the desired torque. This will allow, for the same nut, to have several possible tightening values ).

6/ As a result, nut body parts No. 1 and tapped central part No. 2 are now separated, which means that the hexagonal head nut body is free to rotate (clockwise and anti-clockwise).

**Result of a clamped part that cannot be dismantled with a spanner, since the body of nut N°1 is free to rotate.

The nut can be cut using a grinder of course, if it is visible. But it will suffice to provide a housing in the form of a bore for the nut, in the part to be tightened, so that the assembly is unremovable and inaccessible by all tools. (See hatched mark (T) in figure N°1).

The device according to this invention makes it possible to initially make a tight part unremovable.

This same device also makes it possible to tighten this same part to the correct predetermined tightening torque, without the need to systematically check with a torque wrench.

Note also that with the same nut, several tightening torques are possible.

Claims (4)

: Nut of various possible materials, broken down into several internal parts, whose shapes and technical characteristics make it at the same time unremovable and limits its tightening torque, (by internal breakage of one of the parts). Nut characterized in that it comprises a body (1) having a bore into which is inserted another part (2) which constitutes the thread of the nut. : Device comprising a nut according to claim 1 characterized in that a part (3) (of various materials, of various shapes, of various thicknesses and of various lengths, depending on the desired torque) called "fuse" serves as a link between the body of the nut (1) and the thread (2). : Device according to claim 2 characterized in that any imprisonment system (4) holds the parts (1), (2), (3) together, respectively the nut body, the part forming the tapping, and the so-called "fuse" part. : Device according to one of claims 2 or 3, characterized in that the term "fuse" indicates all mechanical systems breaking, which can separate the central body of the nut (tapping), the outer body (hex shape or other) , after tightening.