RU2717723C1 - Anti-vandal nut with self-tightening effect - Google Patents

Abstract

FIELD: machine building.

SUBSTANCE: invention relates to machine building, particularly, to self-tightening nuts for connection of parts and assemblies operating under permanent or intermittent vibration. Vandal-proof nut with a self-tightening effect includes a cylindrical housing with a through cut made along the helical line with a direction opposite to the thread direction, made on the inner surface of the housing, collar on working end face of cylindrical shape, inner surface of housing has taper 2°, expanding in direction of working end of nut. There is a process hole in the housing, in which the screw cut is completed.

EFFECT: technical result consists in improvement of reliability due to higher rigidity of structure, since nut, having high hardness, in swirling calibrates surface of bolt and completely squeezes due to press fit.

9 cl, 4 dwg

Description

The invention relates to the field of engineering, more specifically: to self-tightening nuts for connecting parts and assemblies operating under the influence of constant or periodically occurring vibration (railways, vehicles, iron bridges, attractions, etc.).

There are various technical solutions in this area.

So known patent RU for invention No. 2199035 (IPC F16B 37/12, B21F 35/00, B21F 3/04, B21H 3/08, B21D 11/0; published. 02.20.2003) .. The spring nut contains a housing with internal thread , a turnkey place, while the body is made in the form of a cylindrical spring from a wire that has a rectangular or square cross section, while the direction of winding is opposite to the direction of the thread, the ends of the turns are bent at an angle equal to 30-60 °. A gear rim is made on each of its ends. The turnkey seats are made at the ends of the nut in the form of lead ledges.

Known RU patent for the invention No. 2241870 (IPC F16B 39/24; F16B 39/36; F16B 39/14, published. 10.12.2004). The self-locking nut contains a central threaded hole, an insert in the form of a washer for locking the nut on a bolt or stud and a cylindrical seat for accommodating the insert. The nut is made with a conical recess located above the cylindrical seat for accommodating the insert, said insert is made in the form of a radially elastic incomplete turn of a flat spiral, the ends of which are deaxial, and the contour of the insert is made on a conical surface corresponding to the taper of the nut recess.

A split nut is also known (see JP Patent No. 47-43099, published. 1972). The design may have a self-tightening effect, but since this effect is uncontrolled, there may come a moment when the front end of the nut can not withstand heavy loads and opens so that it breaks or disengages from the bolt, since the size of the variable section within one turn varies.

Known patent for invention PL No. 1591676 (IPC F16B 37/06, published. 06/29/2007). The nut has a head and a polygonal tail of the outer diameter. The front surface of the shaft portion has a circular outer diameter.

Known international application WO No.2019190116 (IPC F16B 37/12; F16B 39/10, published. 03.10.2019). A nut with a spring configured to change the clamping force in accordance with the direction of clamping of the bolt, the nut to prevent loosening comprises: a stopper inside the spring chamber in which the spring is installed, which allows you to grab and hold the lower end of the spring when the bolt is weakened by a rotational force equal to a predetermined threshold value or more and a support made on the opposite side of the stopper to hold the bottom of the spring.

The disadvantages of the known solutions include the following: in all of the above technical solutions there is no self-tightening effect, since the end face of the nut does not have a sufficient contact area for the transmission of torque that occurs during the vibration of the connected elements, respectively, the necessary reliability of the known nuts is not provided and may occur the moment when the front end of the nuts cannot withstand heavy loads and opens so much that it breaks off or disengages from the bolt and the worker disappears suspended load.

A number of patents are also known in which the problem of self-tightening nuts is solved.

UA patent No. 40711 (IPC F16B 37/08, published. 08/15/2001). The nut contains a body with internal thread and places on a turn-key basis. The nut casing is made in the form of a cylindrical spring from a wire or profile, for example, of rectangular or square cross-section with the opposite direction of the internal thread, the direction of winding of the coils, the coils being made in the form of rings with a bend of each following 30-60 degrees at the points of their connection.

UA patent No. 81232 (IPC F16B 37/08, F16B 39/284, published. 02.15.2005). The nut has a housing made with end bearing surfaces, and a Central hole with a thread in the named housing. The body is made in the form of a spiral element, the turns of which are directed opposite to the threads in the central hole of the body. The ends of the spiral element are made with radially spaced pointed edges protruding beyond the boundaries of the end bearing surfaces.

UA patent No. 59898 (IPC F16B 31/00, F16B 37/08, published. 16.08.2004). The nut is made in the form of a spiral element with an internal thread, the turns of which are directed opposite to the turns of the spiral element, and the surface of the washer that is in contact with the nut is made spiral with a stop, which is made with the possibility of interaction with the front end of the turn of the spiral element; in this case, an annular protrusion is made on the end surface of the washer from the side of the nut, the inner diameter of which exceeds the outer diameter of the nut.

UA patent No. 69115 (IPC F16B 37/08, F16B 39/282, published. December 25, 2007), which is the closest to the proposed technical solution, respectively, adopted as a prototype. The self-locking nut includes a housing, which is made in the form of a spiral element with end supporting surfaces, and a hole, which is made in the housing with a thread, the turns of which are directed opposite to the direction of the turns of the spiral element. The end bearing surfaces are made conical with the orientation of the tops of the cones inside the nut. Moreover, the tops of the cones are made with an angle in the range of 150 ° -170 °.

The disadvantages of the prototype are:

- since the nut consists of two parts - the washer and spring, the costs of its manufacture and operation increase,

- it is very difficult to tighten such a nut due to the fact that the thread in the nut is cylindrical, with an interference fit over the press fit (otherwise it will not self-tighten), it is very inconvenient to tighten it due to the absence of a chamfer on the bolt,

- This design is not anti-vandal, since it can be unscrewed for the free end of the spring.

Thus, the technical problem of the known design of nuts is the design complexity, lack of reliability, as well as the lack of safety when using them due to the fact that they do not have anti-vandal properties. The proposed design will solve this problem, due to the lack of the described disadvantages.

The technical result consists in simplifying the design while improving reliability and safety of use.

The technical result is achieved by the fact that in the anti-vandal nut with a self-tightening effect, comprising a cylindrical body with a through cut made along a helical line with a direction opposite to the thread direction made on the inner surface of the housing, according to the invention, a cylindrical flange is made on the working end face, inner surface the housing is made with a taper of 2 °, expanding in the direction of the working end of the nut.

Moreover, a technological hole is made in the housing, in which a screw cut ends.

Additional features of the invention:

- the flange has one or more pulling spikes, the end of which is made together with the flange, and its base - together with the body;

- a free turn of the screw housing of the nut ends with a flat fifth (for the possibility of dismantling) or a sharp edge (for the impossibility of dismantling);

- a through cut along the axis of the cylinder along a helix contains 1.5-3 turns made with a variable pitch.

In the second embodiment, the technical result is achieved in that the nut is vandal-proof with a self-tightening effect, comprising a cylindrical body with a through cut made along a helical line with a direction opposite to the thread direction made on the inner surface of the housing, according to the invention, the nut body in its upper part has hexagonal shape, the inner surface of the housing is made with a taper of 2 °, expanding in the direction of the working end of the nut, and in the upper part of the housing you the technological hole is filled in which the screw cut ends.

Additional differences are:

- a free turn of the screw housing of the nut ends with a flat fifth or sharp edge;

- a through cut along the axis of the cylinder along a helix contains 1.5-3 turns made with a variable pitch.

The invention is illustrated by the following graphic materials:

- FIG. 1 and FIG. 2, which shows the variants of the proposed nut with a shoulder (in Fig. 1, the collar has one drive spike, in Fig. 2 - six lead spikes);

- FIG. 3, which shows a variant of the proposed nut with a hexagonal part of the housing;

- FIG. 4, which shows all kinds of nuts shown in FIG. 1,

Where:

1 - screw section along the axis of the cylinder;

2 - shoulder;

3 - the inner surface of the housing;

4 - technological hole;

5 - flat heel of a free coil;

6 - lead spike;

7 - sharp edge of a free turn;

8 - the hexagonal part of the nut housing.

An anti-vandal nut with a self-tightening effect includes a cylindrical body with a through cut 1 made along a helical line with a direction opposite to the thread direction (to create radially directed elastic forces) made on the inner surface 3 of the body. The through section 1 along the axis of the cylinder along the helix contains 1.5-3 turns made with a variable pitch.

In one embodiment, the nut has a cylindrical flange 2 on the working end face, the inner surface of the housing is made with a taper of 2 °, expanding in the direction of the working end of the nut, and the technological hole 4 is made in the housing (to relieve stresses after hardening and to protect against quenching cracks at the end screw cut, since it has a thickness of 0.1-0.3 mm), in which the screw cut 1 ends.

The shoulder 2 has one or more towing spikes 6. They are stops for contact with the key element for loosening the nut. Moreover, to unscrew the proposed nuts, wrenches specially made for a different number of driving spikes 6 are used, which completely excludes the possibility of unscrewing these nuts with ordinary wrenches, and it also becomes possible to produce wrenches of various configurations by order of various customers.

The free turn of the screw housing of the nut ends with a flat heel 5 or a sharp edge 7.

Flat heel 7 is used for additional emphasis when unscrewing the nut. Thus, the embodiment with the fifth 5 is for nuts that can be unscrewed, while the embodiment with a sharp edge 7 is for nuts, the unscrewing of which is not provided.

Flange nuts 2 are designed for use with extreme loads, up to breaking the bolt.

In the second embodiment, the nut casing in its upper part has a hexagonal shape 8, in the upper part of the casing a technological hole 4 is made in which the screw cut 1 ends, which is obtained by laser cutting. In a most preferred embodiment, the height of the rigid hexagonal portion of the nut housing refers to the height of the elastic cylindrical portion as 2: 3. This ratio may vary depending on the technical specifications.

In this embodiment of the nut, the free turn of the screw housing of the nut can also end with a flat heel 5 or a sharp edge 7.

Thus, the embodiment with the fifth 5 is for nuts that can be unscrewed, while the embodiment with a sharp edge 7 is for nuts, the unscrewing of which is not provided.

Nuts without collar with hexagonal part 8 of the casing are designed for loads that do not allow breaking of the bolt.

In the present invention, the internal thread in the nut is tapered, which makes it possible to make a front turn with a gap, as on a regular nut, then it can be easily twisted manually by one revolution, not more, because then, already without a gap, the nut will begin to calibrate the thread profile of the bolt .

The conical thread should not have fillets at the tops and troughs (in order to create a gapless elastic contact between the thread profile of the nut and the thread profile of the bolt), and the front turn should manually screw it onto the bolt for at least 1-1.5 turns.

The execution of the thread of the conical shape allows full contact with the cylindrical thread of the bolt, on which, as the nut is tightened, the thread surface of the bolt with the nut thread is calibrated.

In order to increase the rigidity of the nut, its body, as it is twisted, expands and creates a radial pressure that is evenly distributed over the entire surface of the thread of the bolt located under the nut. In this case, the theorem of N.E. Zhukovsky about three turns, does not work. Therefore, all turns, at maximum axial load, work simultaneously, and the breaking axial force depends on the number of turns on the nut.

Nut Technology

Billets for the manufacture of the housing of nuts are made from a standard pipe made of steel 40X.

The nut body is manufactured by cold or hot stamping. The surface for threading should be without scale and hardening. Heat treatment is recommended - “improvement”.

When cutting the technological hole 4 with a laser, the cylindrical surface and the threaded surface of the hole are quenched to a very high hardness. As a result, thread elements caught under the laser beam acquire the property of a cutting tool and the ability to calibrate the thread profile of the bolt. As a result, the thread of the bolt and the thread of the nut, as they are screwed on, completely begin to abut against each other along the contact profile. Outside the technological hole, the cut part of the body opens and is completely lapped together with a strong radial compression of the thread of the bolt.

Special taper threads are made with a general slope of 2 degrees on a thread milling machine. The average diameter of the thread on the first turn of the nut should be such that the first turn of the nut can be twisted “by hand”.

Further, the nut is subject to a heat treatment process consisting of two stages: hardening and tempering (to relieve stresses from hardening).

The final operation is laser cutting of the nut housing along a helical line with a given step in order to create a lateral screw cut with increased hardness at the cutting site. The cutting operation is performed using a laser, starting from the end of the conical body, and ending with the cutting of the technological hole for stress relieving.

The proposed design has anti-vandal properties. The anti-vandalism of a nut is a property of preventing its loosening. In the proposed design, when trying to unscrew it, the elastic part of the body compresses the bolt the more, the greater the torque applied to unscrew it. Thus, an anti-vandal nut is a nut that can only turn in one direction, in the direction of its tightening. So the property of spinning in one direction is not only anti-vandalism, but also self-tightening, which stops if the vibrations dampen. After rain or sudden temperature changes, changes occur in the bolted connection. Rain causes rust in the contact area and the tightening weakens as the rust breaks. Temperature fluctuations also change the tightening force of the threaded joint. And when large loads occur, the nut experiences fluctuations from these loads, then on loosening, then tightening. Therefore, if it is impossible to unscrew this nut, but it is possible to tighten it, then it is twisted by a small amount with each new oscillation, until they loosen and so on.

Test

In the proposed design, the thread is tapered, which allows you to turn the nut by hand the first turn, and then, using a special key, the nut begins to compress the bolt in the same way as the press fit. You can even screw such a nut if the bolt is without a chamfer or with a clogged or wrinkled thread. Currently, bolts are produced with thread obtained by knurling, this method of obtaining threads allows 3-4 times to increase the tensile strength of the bolt, but the thread tops are out of tolerance, and sometimes the angle of inclination is violated. However, the proposed nut calibrates the thread profile, and thereby fully compresses the thread profile of the bolt with a total force of about 10-12 tons, which guarantees the safety of the thread of the bolt and prevents its collapse. Tensile tests showed that due to the press fit, at 42 tons of axial load, the bolt broke, and the nut remained operational and the thread remaining on the part of the bolt after the break also remained operational.

In parallel, tests were carried out with a standard nut, in which it slid off the bolt at 12 tons of axial load.

Thus, the proposed anti-vandal nut with a self-tightening effect has increased reliability by increasing the rigidity of the structure. Since the nut has a high hardness, it tightens the surface of the bolt when tightened and completely compresses it due to the press fit. Using the proposed nut also does not require the use of any additional washers, including spring washers, which increases the usability.

Claims (9)

1. Vandal-proof nut with a self-tightening effect, comprising a cylindrical body with a through cut made along a helical line with a direction opposite to the thread direction made on the inner surface of the housing, characterized in that it has a cylindrical shoulder on the working end, the inner surface of the housing is made with taper 2 °, expanding in the direction of the working end of the nut, moreover, a technological hole is made in the housing, in which a screw cut ends. 2. A nut according to claim 1, characterized in that the collar has one or more towing spikes. 3. The nut according to claim 1, characterized in that the free turn of the screw housing of the nut ends with a flat heel. 4. The nut according to claim 1, characterized in that the free turn of the screw housing of the nut ends with a sharp edge. 5. A nut according to claim 1, characterized in that the through cut along the axis of the cylinder along a helical line contains 1.5-3 turns made with a variable pitch. 6. Vandal-proof nut with a self-tightening effect, comprising a cylindrical body with a through cut made along a helical line with a direction opposite to the thread direction made on the inner surface of the housing, characterized in that the nut housing in its upper part has a hexagonal shape, the inner surface of the housing made with a taper of 2 °, expanding in the direction of the working end of the nut, and in the upper part of the housing there is a technological hole in which the screw zrez. 7. The nut according to claim 6, characterized in that the free turn of the screw housing of the nut ends with a flat heel. 8. The nut according to claim 6, characterized in that the free turn of the screw housing of the nut ends with a sharp edge. 9. The nut according to claim 6, characterized in that the through cut along the axis of the cylinder along the helical line contains 1.5-3 turns made with a variable pitch.

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