LT3301B - A self - locking nut - Google Patents

Abstract

This lock screw-nut, which has an upper flange with a thread, is made with a longitudinal U-shaped flute grooving, which forms orbicular arc segments with a spiral outer spring reduction. The spring is zinced while heating and made of spiral steel, and can operate when the temperature is not lower than 250 degrees C. If the spring operates at a higher temperature than 250 degrees C, it is made of stainless steel, and if it operates at a much higher temperature, it is covered with copper by electrolysis.

Description

The present invention relates to a locking nut having a cylindrical end pressed against a helical spring.

There are several types of locking nuts having a cylindrical end made with vertical grooves defining circular arc segments for elastic compression due to the radial action of the outer helical spring.

Such a locking nut is described in U.S. Pat.

The nut has a number of shortcomings, mainly due to the tension of the vertical grooves made in the cylindrical end or in the nut flange, namely:

- it is difficult to re-use the nut once it has been unscrewed due to dirt and foreign matter entering the grooves during use. Thus, if it is necessary to re-use the nut, it is necessary to perform a cleaning operation, cleaning with compressed air, solvents or mechanical means.

- resistance to longitudinal bending, thus resulting in compression, wall deflection limited by a spring because, after corresponding bending in the radial direction, the upper edges of the arc segment contact one another such that the usefulness of the nut becomes problematic when using a screw with a slotted thread.

The above deficiencies have been solved by a device according to U.S. Pat. 4,893,977.

The patented locking nut is distinguished by the fact that its flange is provided with a number of grooves of type V and U of sufficient width to avoid the above disadvantages caused by the groove of the groove. The disadvantages, the elimination of which is an object of the present invention, are not directly related to the last patent, but are related to modern technology if they are not clearly shown.

Just as a spiral spring with a nut must be protected against oxidation, it is an acceptable solution to saturate the spring with phosphorus made of spring steel and, alternatively, to make the spring from stainless steel (above 250 ° C).

As a result, it appeared that:

1. Phosphation does not prevent oxidation;

2. When the spring is made of stainless steel, other disadvantages occur, such as:

- excessive price justified only by the type of nut intended for use at high temperatures (not above 250 ° C);

use of springs due to nuts made for high temperatures (above 250 ° C) such that at lower temperatures it is suggested to use conventional springs (made of spring steel) which have better flexibility and higher torque during braking;

- a given spring made of stainless milk has a lower torque than a spring made of spring steel.

It is an object of the present invention to provide a nut which does not have the above disadvantages and has the following advantages:

- low price;

- resistance to oxidation;

- use of the nut at various temperatures.

It should be noted that modern technology is available for at least three applications, at high temperatures above 250 ° C, always with springs made of stainless steel:

(a) low carbon steel nut;

(b) high carbon steel nut;

(c) Stainless steel nut.

In the solutions described above, especially in cases (a) and (b), too high a screw or screw engagement after high temperature application (400-500 ° C).

Solution c) has a lower number of phenomenal situations but can sometimes cause inconvenience. In this case, the inconvenience means that the screw itself is loosened when the nut is unscrewed from its socket or worse.

Thus, if this inconvenience occurs during a one-time inspection or after-sales service of a machine (which may contain 10 nuts and nuts), it causes additional interference; in the first case the replacement of a screw with a larger diameter than the previous one, in the second case the problem is much larger because of the need to weld and disassemble the screw with additional equipment, bearing in mind that this operation is performed in a very uncomfortable position for vehicles.

The object of the present invention is to avoid these disadvantages, provided that the nut is made in such a way that it is easy to disassemble by controlling its displacement, which can cause gas leakage and consequently fire sealing gaskets.

The above objects and advantages of the present invention are set forth as they will be described, the object of the invention being an improved locking nut consisting of a threaded top flange made of U-shaped longitudinal grooves defining a plurality of circular arc segments compressed by an outer helical spring within the flange. the width is such as to prevent contact between the circular arc segments, which is due to the fact that the spring is zinc-coated at high temperatures before being screwed in to better protect against oxidation.

Another feature of the present invention is that the nut is oxidized by electrolysis to prevent diffusion between the nut and the bolt.

Another feature of the present invention is the production of a spring operating at a temperature below 250 ° C from spring milk by galvanizing.

Another feature of the invention is the manufacture of a spiral spring made of stainless spring steel when operating at temperatures above 250 ° C.

The invention will now be described in detail with reference to the drawings, wherein the exemplifying embodiment is not limited to the invention.

The axonometry of the drawing shows the locking nut.

The nut is marked 1 and screws onto the threaded rod, not shown in the drawing of the nut.

The nut is made with a flange 3 on which a helical spring 5 is wound, which acts by radially pressing the flange 3 and a threaded rod on which the nut 1 turns, thanks to the wide U-shaped grooves 7 in the flange.

The grooves 7 shown in the flange 3 form a series of circular arc segments 9 formed with a small upper outer edge. A notch is made on the outer surface of the nut 1, where a helical spring 5 is inserted which wraps the flange 3 and radially clamps the segments 9 about the threaded rod on which the nut 1 is screwed.

As described in U.S. Patent No. 4,893,977, there is no need to describe the remaining structural nut parts.

Claims (4)

DEFINITION OF INVENTION 1. A locking nut having an upper threaded flange made with U-shaped longitudinal grooves forming circular arc segments in the flange, compressed by an external helical spring having a width that prevents contact with said segments, characterized in that the spring is pre-threaded zinc-plated. 2. A nut according to claim 1, characterized in that, for use at a temperature below 250 ° C, the galvanized coil spring is made of spring steel. 3. Nut according to claim 1 or 2, characterized in that the helical spring is made of stainless spring steel. 4. Nut according to claims 1-3, characterized in that it has a copper electrolytic coating to protect the duck from corrosion.