Screw/non-threaded nut connection

The invention relates to the connection made between screw and non-threaded nut, taking advantage of the dimensional change due to the increase or decrease of temperature inside. This connection can be used in a large number of engineering applications.

The connection between the screw and nut is one of the most important tools in the industry. The enormous achievements of man in industrial applications would not have happened without this valuable invention. Nevertheless, we can discern some disadvantages of this application. First of all, whereas due to globalisation of the economy, there should be a common global specification applied by everyone, there are currently various types of threads with different steps and expressed with different measuring sizes, resulting in disagreeable consequences for global cooperation. Furthermore, time and again, the threads themselves, due to their materials, type of application, or even the way of application, can suffer damages, with serious consequences incurred by the application.

Besides correcting the above shortcomings, the major advantage of this invention focuses on the potential of very good and stable connection due to the strongest forces in the world, which are the forces of contraction - expansion. The invention is described below by way of example and reference to the accompanying drawings.

Figure 1 shows in section the connection between two sheets (3, 4) made by means of the screw (1) and the nut (2). Inside the screw (1) we discern the electrical resistance (5), the electrical contacts (+, -). While inside nut (2) there is electrical resistance (6) with electrical contacts (+, -).

Figure 2 shows in section the connection between two sheets (3,4) made by means of screw (1) and nut (2). Inside screw (1) we discern gap (5), while inside nut (2) there is gap (6).

Figure 3 shows in section the connection between two sheets (3,4) made by means of the screw (1) and the nut (2). Inside the bolt (1) we discern two separate gaps (5-6), while inside the nut (2) there is gap (7).

In figure 1, the connection between the sheets (3,4) is effected by means of the screw (1) and the nut (2). Initially, the outer diameter (dl) of the screw (1) is smaller than the holes of the respective sheets (3,4) but larger than the inner diameter (d2) of the nut (2). We pass the screw (1) into the holes of the sheets (3,4). We join the electrical contacts of the screw (1) in a voltage, resulting in an increase of its temperature (in some desired level), and thus increase of its dimensions (dl, P). Since the diameter (d2) of the inner surface of the nut (2) is less than the outside diameter (dl) of the screw (1), we connect with an electrical voltage the contacts of the electrical resistance (6) of the nut (2) with a view to increasing its temperature and thus its expansion. When d2 dl, then we pass the nut (2) to the switching position so as to contact with the lower surface of the sheet (4) and remove the voltage at the ends of the nut (2) with a view to cooling and contraction. When the temperature of the nut (2) comes to ambient levels, the diameter (d2) will contract, resulting in strong tightening round the screw (1). We remind here that the dimension (L) of the screw (1) is still higher than its corresponding one in ambient temperature. It's time to remove the voltage from the contacts of the screw (1) with the effect of reducing the temperature, the contraction of the dimensions (P, L) and thus the tightening of the sheets (3,4).

To achieve decoupling of the application, we reverse the process. That is, we first supply current to the electrical resistance (5) of screw (1), causing dilation of the dimensions and thus the length, and later we give current to the electrical resistance (6) of nut (2) so as to cause expansion of diameter (cl2) until d2> dl so we can decouple nut (2) from screw (1).

In the screw/non-threaded nut connection, according to the procedure described above, instead of the electrical resistances (5,6 - figure 1) inside the screw (1) and the nut (2), we can respectively form two gaps (5, 6 - 2 project) and circulate heat (e.g. steam) through them, and so in this way achieve the expansion of the dimensions that is necessary for the connection of this type.

For tightening the sheets (3,4) with the help of screw/non-threaded nut connection, to avoid any problems in the connection or decoupling, due to heat transfer from the nut (2) to the screw (1), since they come in contact with each other, we form the gap (6- figure 3) at the bottom of the screw (1), so as to release through it a cooling means (e.g. freon). The whole procedure followed is the same as that described above.

It is worth mentioning that we cannot increase the temperature of the screw (1) and nut (2) beyond _^ some marginal temperatures, because it could change the internal structure of our material, changing accordingly their quality and characteristics, such as hardness and elasticity. These limit temperatures are determined each time by the type of material, the application and our requireme