SU1541438A1 - Method of producing a threaded joint - Google Patents

Abstract

The invention relates to mechanical engineering, in particular, to methods for assembling fastening threaded joints and can be used in assembling parts with both through and blind hole apertures. The purpose of the invention is to expand the functionality. Twist the bolt rod at an angle of 130 ... 215 in the direction opposite to the direction of the torque when tightening. Cut on it a thread. The joint is tightened by applying a moment to the bolt head. In this case, the twisted rod is unwound by the magnitude of the elastic deformation angle. The implementation of the method will reduce the complexity and cost of assembly of threaded connections. 2 Il.

Description

The invention relates to mechanical engineering.

The purpose of the invention is to expand the functionality.

FIG. Figure 1 shows a bolt after tightening a rod by an angle z; in fig. 2 - threaded connection after tightening.

The method is as follows.

in a way.

First, the cylindrical rod 1 of the bolt is tightened at an angle of 130 to 215 within its plastic deformation, applying a torque M, directed in the direction opposite to the direction of the torque Mgat when tightening the threaded connection. Then, a thread is threaded on the twisted rod 1, the bolt is installed in the threaded connection of parts 2 and 3 and tightened in a blind hole 4.

application to the head 5 bolts torque MiclT. In this case, the twisted rod is unwound by the magnitude of the elastic deformation angle. If the torque Kp in the thread is less than the torque Kg at the end of the bolt head, then under the action of vibration loads, when periodic oscillations of the load cause corresponding oscillations of the axial elastic deformation of the rod, the threaded connection weakens due to a change in the friction of rest to the amount of motion friction, which causes micro-displacement surfaces of threaded parts relative to each other in the direction of twisting without special tools (direction of Maine)

If the moment Kp in the thread is greater than the moment Mt at the end of the bolt head, then under the action of the same vibration loads and a change in the amount of friction

ate

Ј

four

CO 00

rest to the magnitude of the friction movement, the relative micro displacement of the parts in the direction of unscrewing (the direction of the moment,) is excluded, since the untwisted rod to the angle Ч1 0 is reliably held by the axial force from turning.

The magnitude of the bolt tightening moment is determined from the indications of the dynamometric key, and the magnitude of the moment of unwinding of the rod within the elastic deformations is determined using strain gauges.

Example. In blind holes for tightening M10 x 1.5 bolts with a length of 40 mm from steel 38XA, the permitted tightening torque is 220 kg / cm. Permissible axial load when tightening is 1500 kg. The angles of plastic twisting of the cylindrical rod for bolts Ml0-1.1 and 40 mm long and (ev of 85 kg / mm1 is 130-215.

The contact area of the end surface of the bolt head with the threaded joint part is

rt

Ft 124.3 mm, and the contact area of the thread surface of the bolt rod with another part of the same joint is Fp 165.87 mm.

In those cases when the length of the standard bolt is the smallest, you need to tighten it at an angle of 130 as well. when the length of the bolt is greatest, you need to tighten the angle of 215. Intermediate values for the length of standard bolts, for example, 4 to 280 mm, need to tighten an ira angle equal to the nominal value of the ratio

- 4 + - tlA-i6,

max L6

Q

five

0

where is the nominal amount of bolt rod tightening; H - the smallest value of the angle of twist of the bolt rod, for example 130;

 - the largest value of the angle of twist of the rod, for example,

L6 - the greatest length of the bolt within the limits of GOST;

1B - the length of the bolt, the core of which is necessary to tighten.

The implementation of the proposed method will allow you to get a reliable connection, both when assembling parts with through-threaded holes and with blind holes, to reduce the labor intensity and cost of assembly of threaded connections, and to reduce their additional control and maintenance.

Claims (1)

Invention Formula A method of obtaining a threaded joint, comprising the following operations: installing a bolt into the threaded hole, tightening the threaded joint by applying a torque to the bolt, and twisting the cylindrical bolt rod at an angle proportional to the moment on the bolt head, in the direction opposite to that moment, which differs that, in order to extend the functionality, the cylindrical bolt rod is twisted before it is installed in the threaded hole before being threaded on the rod, and Root torque is applied to the bolt head. J # 2