The present invention refers to an unscrewing- preventing system for bolts.

The invention finds application in the field of mechanics. In mechanics, the bolt is a component formed of a screw (head with threaded stem) and a

+ nut with a corresponding thread.

The nut, usually of an hexagonal shape, is screwed on the stem of the screw to connect parts which must be mutually assembled. When there are vibrations, stresses or impacts, the nut tends to be loosened, so that different solutions are adopted, among which the addition of a lock nut.

Currently, it is foreseen that a nut is assembled on the screw, followed, for a better safety, by a lock nut. However, cases can occur in which the loosening of the lock nut occurs and, consequently, the nut is also loosened. Documents GB-A-238 487, US-A-1 539 213 and US- A-2 301 634 disclose unscrewing-preventing systems according to the prior art.

Object of the present invention is solving the above prior art problems, by providing an unscrewing-preventing system for bolts which is efficient, unmovable and capable of being easily made .

The above and other objects and advantages of the invention, as will appear from the following description, are obtained with an unscrewing-

+ preventing system for bolts as claimed in Claim 1.

Preferred embodiments and non-trivial variations of the present invention are the subject matter of the dependent claims.

It is intended that the enclosed claims are an integral part of the present description.

The present invention will be better described by some preferred embodiments thereof, provided as a non-limiting example, with reference to the enclosed drawings, in which, in Table I, the following are shown: in Figure 1 a first preferred embodiment of the system of the present invention; in Figure 2 a second preferred embodiment of the system of the present invention; in Figure 3 a third preferred embodiment of the system of the present invention; in Figure 4 a fourth preferred embodiment of the system of the present invention; and in Figure 5 a fifth preferred embodiment of the system of the present invention, while Figure 1 in

Table II shows a sixth preferred embodiment of the system of the present invention.

With reference to the Figures, a preferred embodiment of the unscrewing-preventing system for bolts of the present invention is shown and

+ described. It will be immediately obvious that numerous variations and modifications (for example related to shape, sizes, various colors and parts with equivalent functionalities) could be made to what is described, without departing from the scope of the invention as appears from the enclosed claims .

The present invention consists in unscrewing- preventing systems for bolts (with a simple use or a biting catch use) in which the male has a single or double threading; it has deformable inserts and reductions with tightening functions and, in the mentioned cases, uses special nuts. The material to be used for each of the solutions included in the above drawings must be complying with the needs corresponding to every single case. Therefore, the inventive idea is extended to any material which is used for making it.

In Table I, Figure 1 shows a first preferred embodiment of the unscrewing-preventing system of the present invention, which has a screw 1, a nut 2 and a lock nut 3. The screw 1 has a first threading a having a first diameter and a first inclination

+

(or orientation) of its thread, and a second threading b having a second diameter, smaller than the first diameter, and a second thread inclination opposite to the first inclination. The lock nut 3 is equipped with a holding chamber c obtained on its side in contact with the nut 2, in order to perform the optimum seal when tightening.

Figure 2 shows a second preferred embodiment of the unscrewing-preventing system of the present invention. In such Figure, the chamber c is replaced by a chamfered cone c', which allows obtaining the same functionality of the chamber c, but with a simpler construction and a better assembling functionality. Figure 3 shows a third preferred embodiment of the unscrewing-preventing system of the present invention, in which at least one ring-type insert 4 is introduced, to be placed in the chamber c'', which in this case is obtained both in the nut 2, and in the lock nut 3. The insert 4 can be made of steel, copper, brass, teflon and other plastic materials. The tightened coupling of the external diameter of the insert 4 with the diameter of the chamber c'' ensures the tightening, all together, of the three parts.

+

Figure 4 shows a fourth preferred embodiment of the unscrewing-preventing system of the present invention, in which an external cylindrical reduction on the nut 2 is proposed. The lock nut 3 is instead made greater as longitudinal extension, with a chamber c whoce diameter fits in the external reduction of the nut 2. The thereby generated friction ensures the tightening. Finally, Figure 5 shows a fifth preferred embodiment of the unscrewing-preventing system of the present invention. Therein, the screw 1 has a cylindrical reduction at the end, and a lock nut 3 with a chamfered cone for the entry and a cylindrical reduction for coupling with the end of the screw 1. The thereby generated friction ensures the tightening in c' ¹ '.

In Table II, Figure 1 shows a sixth preferred embodiment of the unscrewing-preventing system of the present invention, where the lock nut 3 is instead made shorter as longitudinal extension with respect to the nut 2, while the holding chamber c is removed. The thereby generated friction ensures the tightening.