RU2292491C1 - Self-locking screw - Google Patents

Abstract

FIELD: mechanical engineering.

SUBSTANCE: self-locking screw comprises V-shaped thread and trancated tops of teeth and locking zone. The locking zone is defined by the locking members set on the sides of tooth thread and made to form a projections whose height is determined from the formula a ≥ δ/2n = (ES + ei)/4n, where a is the height of the projection with respect to the side of the teeth, δ is the space between the sides of the tooth thread and nut, ei is the lower limit of deviation of tolerance on the mean diameter of the screw thread, ES is the upper limit of the deviation of the tolerance on mean diameter of the nut thread, and n is the number of hollow turns of the nut thread.

EFFECT: reduced labor consumption for making and expanded functional capabilities.

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Description

The invention relates to mechanical engineering, in particular to detachable threaded connections of machine parts, mechanisms, etc.

A self-braking threaded connection is known in which one of the mating parts has a curved profile of one of the threads (US Pat. No. 3,885,613, class F 16 B 39/30, 05.27.75).

The disadvantage of this technical solution is the difficulty in manufacturing due to the need to develop and use a special tool, control over obtaining the desired profile when determining the geometric parameters of the thread. The use of the connection depends on the location of the locking elements along the length of the thread, which limits the use of parts of the same size in various designs.

A self-braking threaded connection is known having a special profile in the form of a rectangular section of the tooth tip (US patent No. 5738472, class F 16 B 39/30, 04/14/98).

The disadvantage of this technical solution is the difficulty in manufacturing due to the need to develop and use a special tool.

A self-braking threaded connection is known that contains male and female threaded parts mated to one another, one of which is made with a constant thread pitch, and the other has a locking portion, the thread pitch on which is greater than the thread pitch on the mating part (Russian patent No. 2070995, class F 16 B 39/30, 12/27/96).

The disadvantage of this technical solution is the difficulty in manufacturing and controlling the difference in the pitch of the threads covered and covering the threaded parts, due to the smallness of its value, which requires high precision manufacturing and measurement. The use of the connection depends on the location of the locking zone along the length of the thread, which limits the use of parts of the same size in various designs.

Closest to the proposed one is the design of a self-locking screw with a V-shaped thread having a locking zone formed by two adjacent thread teeth made with truncated tops at half turn and inclined to each other at an angle smaller than the angle between the teeth of the remaining threads (patent USSR No. 350287, class F 16 B 39/30, 09/04/72).

The disadvantage of this technical solution is the difficulty in manufacturing due to the need to develop and use a special tool. The use of the connection depends on the location of the locking zone along the length of the thread, which limits the use of parts of the same size in various designs.

The technical result of the invention is the reduction of the complexity of manufacturing, the possibility of using one screw size in various connection designs by locking the screwed part on any screw thread length.

The essence of the invention lies in the fact that the self-locking screw with a V-shaped thread and truncated tops of the teeth has a locking zone formed by locking elements on the side surfaces of the teeth of the thread, made in the form of a protrusion, the height of which is determined by

where a is the height of the protrusion relative to the lateral surface of the tooth;

δ is the gap between the lateral surfaces of the teeth of the thread of the screw and nut;

ei is the lower deviation of the tolerance field of the average screw thread diameter;

ES is the upper deviation of the tolerance field of the average diameter of the nut thread;

n is the number of full threads of the nut thread.

The thread in the locking zone is formed by truncated tooth tips and locking elements on the side surface of the thread profile. The height of the protrusion is selected so that when the screw engages with a standardly cut hole, the gap between the threads of the parts to be joined is gradually selected by the protrusions, and the parts are jammed relative to each other at the last turn of the screwed part. The connection is tightened to the required thread length with an additional moment of resistance arising from the deformation of the locking elements by the lateral surfaces of the thread of the screwed part, which allows the use of a screw of the same size in various designs. The presence of locking elements on the lateral surfaces of the thread teeth made in the form of a protrusion does not require the development and use of a special tool, since it is enough to roll a standard screw between smooth rollers, which reduces the complexity of manufacturing.

Figure 1 presents a side view of the screw; figure 2 - standard pair, as the source for the calculation; figure 3 - threaded pair in the working position; figure 4 is a cross section of two teeth of a thread full-scale sample with a height of the locking elements equal to a.

A self-locking screw (Fig. 1) with a V-shaped thread and truncated peaks 1, having a locking zone formed by locking elements 2 located along the entire length of the thread on the side surfaces 3 of the thread teeth, made in the form of a protrusion, the height of which is determined by the dependence:

where a is the height of the protrusion relative to the lateral surface of the tooth;

δ is the gap between the lateral surfaces of the teeth of the thread of the screw and nut;

ei is the lower deviation of the tolerance field of the average screw thread diameter;

ES is the upper deviation of the tolerance field of the average diameter of the nut thread;

n is the number of full threads of the nut thread.

The connection works as follows. When screwing the nut 4 with the number of full turns of thread n and having an upper tolerance of the tolerance field of the average thread diameter ES (Fig. 2) onto a self-locking screw with a lower tolerance of the tolerance field of the average thread diameter ei, the clearance δ equal to half the sum of the deviations ES and ei , between the side surfaces 3 of the teeth of the thread due to the locking elements 2 in the form of protrusions (figure 3), and at the last thread turn of the nut 4, the gap becomes negative. The locking action is the result of the pressure of the locking elements 2, made in the form of protrusions, on the side surface 3 of the tooth thread of the nut 4. The connection is tightened to the required length of the thread by deforming the locking elements 2 of the self-locking screw on the last turns of the thread of the nut 4.

To obtain a retaining zone, it is sufficient to run a standard screw between smooth rollers, while the tops of the threads are deformed, forming on the side surface of the thread profile locking elements 2 in the form of protrusions of height a (Fig. 4), which does not require the development and use of a special tool and thereby reduces the complexity of manufacturing.

When performing protrusions of height in accordance with the above dependence along the entire length of the thread, reliable jamming of the threaded pair is ensured with a guaranteed tightness of the self-locking screw and allows the use of a screw of the same size in various designs.

Claims (1)

A self-locking screw with a V-shaped thread and truncated tooth tips having a locking zone, characterized in that the locking zone is formed by locking elements on the lateral surfaces of the thread teeth, made in the form of a protrusion, the height of which is determined by

where a is the height of the protrusion relative to the lateral surface of the tooth; δ is the gap between the lateral surfaces of the teeth of the thread of the screw and nut; ei is the lower deviation of the tolerance field of the average screw thread diameter; ES is the upper deviation of the tolerance field of the average diameter of the nut thread; n is the number of full threads of the nut thread.

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