Mechanical fasteners play a vital role in our day to day life. They are used in a variety of applications, right from holding together a piece of furniture that we use, or in our household appliances, or in the machines in our industries, to the hi-tech automobiles or airplanes that we use to travel long distances. Mechanical fasteners are broadly divided into permanent and non-permanent fasteners. Threaded bolts and nuts are one such type of non-permanent mechanical fasteners. Generally, plain nut and bolt assembly require little torque to tighten the plain nut onto the bolt. This also means that the plain nut will easily loosen with the application of little external load or by small vibrations. Conventional Nyloc nuts were developed, where a small washer made of polyamide material, more specifically Nylon 6 or 66, is used within the threaded nut. These require significantly more torque to tighten and accordingly more torque to loosen than a plain nut. However, even for the Conventional Nyloc nuts, there is a limit to the torque applied for tightening and therefore loosening, and for certain applications, it would be helpful if it can be improved and increased. Further, in a plain nut or Conventional Nyloc nut and bolt arrangement, coarse threaded bolts require coarse threaded nuts to mate and fine threaded bolts require fine threaded nuts to mate. That is, a single nut cannot be used to mate with both, coarse and fine threaded bolts. Additionally, an expensive high tensile tap is used for threading the plain nut or Conventional Nyloc nut. A single high tensile tap can produce only a limited number of quality threaded nuts and then it has to be replaced to continue the production of the threaded nuts. Threading is a slow process. All these not only affect the production rate of threaded nuts in a negative way but also adversely affect the cost of production. Keeping above in mind, the inventors; (1) Mrs. Veena Agarwal, and (2) Mr. R. P. Agarwal developed the world’s first Threadless Nyloc Nut.
In the present invention, in the bolt and nut combination, one item i.e. the bolt only is threaded whereas the other i.e. nut is threadless, which itself is a cost-saving. It also significantly increases the rate of production. The threads are replaced by a long Nylon 6 or 66 washer. That is why it is being called “Threadless Nyloc Nut”.
Picture 1 shows how the inside of a “Threadless Nyloc Nut” looks like.
The Threadless Nyloc Nut has a number of spectacular advantages not available with any existing fastening hardware. One size Threadless Nyloc Nut can handle coarse as well as a fine-thread bolt of mating size. This reduces the inventory requirements for that size hardware. There are torque related advantages that will become evident by referring to the results of a test case of M14 Threadless Nyloc Nut, as stated below:
The Threadless Nyloc Nut will not get loosened up even up to about 300 % of the torque value of the Conventional Nyloc nut. ( Fig 1)
The Threadless Nyloc Nut of a particular size can be used for all bolts of that size i.e. for fine as well as coarse threads. This means that the usage of Threadless Nyloc Nut will amount to a great reduction in the inventory costs in comparison to nuts and Conventional Nyloc nuts. (Fig. 2)
For Threadless Nyloc Nut the tightening and loosening up torques required for fine threaded bolts are about 125% of the similar required values for the coarse threaded bolts. (Compare Fig 1 and Fig 2)
Even after many cycles, i.e. tightening and loosening exercise, in this case, ten times, the Threadless Nyloc Nut still requires about 200 % of the respective values of the virgin i.e. first-time use values of the Conventional Nyloc nut. (See Fig 1 and Fig 2)
If the height of the Threadless Nyloc Nut is increased, the tightening and loosening torque increases. This property can be used to design nuts to adjust torque requirements, or of the weight of the nut requirement, as in the case of airplanes, for a given torque. (Fig. 3)
For a given size, in general, if the plain nut requires a tightening torque of less than 1 nm, the Conventional Nyloc nut requires about 4.5 Nm, the Threadless Nyloc Nut of 8 mm height requires about 17 Nm, and the Threadless Nyloc Nut with a height of 12 mm requires about 25 Nm. (See Fig.3)
As no machined threads are made in the Threadless Nyloc Nut, it significantly reduces the cost of production. The production rate also increases.
The Threadless Nyloc Nut has an Indian Patent number 332905 issued. Also, the Threadless Nyloc Nut has International Patent Protection through the Patent Cooperation Treaty which is currently recognized and honored by 153 countries worldwide.