RU2659451C1 - Method for tightening control when assembling threaded connections by impact wrenches - Google Patents

Abstract

FIELD: measuring equipment.

SUBSTANCE: invention relates to the field of metrology, namely to force measuring equipment, and can be used to control the force or torque of the impact tightening of threaded joints. Tightening is performed in several stages (impacts), and the force parameters are measured after each stage of the tightening, while the force parameters are determined by the angle of rotation of the nut for each impact. Possibility of extending the field of application due to the fact that the tightening of the threaded joint is performed in several stages – for several impacts, and the force parameters are measured after each stage of tightening. And the force parameters are determined by the angle of rotation of the nut or wrench key for each impact.

EFFECT: present invention makes it possible to expand the field of use of the known methods due to the possibility of its application to threaded joints with different mechanical compliance.

1 cl, 2 dwg, 1 tbl

Description

The invention relates to the field of metrology, and in particular to load-measuring equipment, and can be used to control the forces or the moment of impact tightening of threaded joints.

A known method of controlling the tightening forces of threaded joints, which consists in the gradual tightening of the nut from the initial position to a given force, which is controlled by the angle of rotation of the nut [1, 2].

и диаметром болта d: если

, способ - неприемлем. А это означает, что в случае коротких болтов возможны значительные погрешности при регистрировании этого силового контролируемого параметра.The disadvantages of this method include low control accuracy, because the use of this method is limited by the ratio between the length

and bolt diameter d: if

, the method is unacceptable. And this means that in the case of short bolts, significant errors are possible when registering this power controlled parameter.

As a prototype, the method of tightening control during assembly of threaded joints by impact wrenches was selected, which provides for the tightening of the threaded connection from the initial state to the set value of the power parameters on the wrench spindle and their subsequent measurement [3]. The final force is determined in accordance with known analytical dependencies.

Common essential features of the known and claimed methods is the tightening of the threaded connection with impact wrenches, which provides for the tightening of the threaded connection from the initial state to the set value of the power parameters on the wrench spindle.

However, the known method is applicable only to control the tightening of the same type of threaded connections with the same thread parameters and the same flexibility of all elements of the connection. This disadvantage significantly narrows the scope of this method.

The basis of the invention is the task of expanding the scope of the known method.

This is achieved by the fact that the tightening of the threaded connection is performed in several stages (in several strokes), and the power parameters are measured after each tightening step. Moreover, the power parameters are determined by the angle of rotation of the nut (or wrench) for each stroke.

The proposed solution provides an extension of the scope due to the possibility of using the proposed method for threaded connections with different flexibility of the connection elements.

The essence of the invention is illustrated by the following graphs, which depict:

FIG. 1 - the dependence of the tightening torque on the angle of rotation of the nut for threaded connections with different compliance with the traditional method of tightening;

FIG. 2 - dependences of the tightening torque on the angle of rotation of the nut for threaded connections with different flexibility when checking the angle of rotation of the nut for each impact.

In FIG. Figure 1 shows the real dependence of the tightening torque on the angle of rotation of the nut (curve 1) and the calculated dependence (straight line 2) for threaded joints with different flexibility. The energies required to tighten such threaded joints to the required moment are equal to the areas of the shaded areas. Obviously, these areas are significantly different, which affects the accuracy of the control with the known method.

The proposed method of controlling the tightening torque is based on the relationship between the current value of the moment M _i and the rotation angle ϕ _i after each i-th impact. This dependence takes place for each specific wrench (for rare impact wrenches, the energy of a single impact A _{e is} indicated in the passport of the wrench), while the energy of a single impact A _e is spent on the work of turning the nut A _G and on the work of elastic twisting of the spindle of the wrench and the tightened parts A _U.

The work spent on turning the nut A _G can be approximately calculated by the following formula:

It should be noted that the dependence (1) will be more accurate, the smaller the angle ϕ _i. . Since the angle of rotation of the nut at the end of the tightening is rather small, relation (1) with sufficient accuracy reflects the value of A _G.

In FIG. 2 also shows the dependence of the tightening torque on the angle of rotation of the nut for threaded connections with different flexibility (curve 3 and curve 4), for the proposed control method. Figure 2 shows that for the same value of the angle of rotation of the nut in one stroke ϕ _1i = ϕ _{2i, the} work spent on turning the nut in one stroke differs slightly (this work is equal to the area of the shaded area) for any type of dependence of the moment on the total angle of rotation nuts. The corresponding tightening torques also differ slightly.

The work that is spent on the elastic twisting of the wrench spindle can be determined by the well-known formula:

where c is the reduced torsional stiffness of the elements of the wrench (for a specific wrench this value is constant).

Then the energy of a single impact And _{e is} determined by the dependence:

Hence, the angle of rotation of the nut after each impact will be equal to:

So, measuring the value of ϕ _i you can judge the value of M, the tightening torque.

For example, for a rare impact wrench of the IE3115A model, taking into account formula (4), the dependence of the rotation angles and the corresponding tightening torques is shown in Table 1.

The proposed invention is a method of tightening control when assembling threaded joints with impact wrenches, allows to expand the scope of application of impact wrenches and increase the reliability of assembled threaded joints.

Information sources

1. Birger I.A. Threaded and flange connections. / I. A. Birger, G. B. Iosilevich. - M.: Mechanical Engineering, 1990. - S. 327-329.

2. Vodolazska N.V. Models, algorithms, and technical methods to help secure the storage of stockings: // Monograph. Donetsk: DVNZ DonNTU. - 2013. - S.24-25.

3. RU 2360786 C2, B25B 21/02 (2006.01), B25B 23/14 (2006.01), 07/10/2009. A method of controlling the quality of the tightening during the assembly of threaded joints with an impact wrench and a device for its implementation / Ustinov V.V. (RU).

Claims (2)

1. A method for controlling the tightening during assembly of threaded joints with impact wrenches, which involves tightening the threaded joint from the initial state to the set value of the power parameters on the spindle of the wrench and their subsequent measurement, characterized in that the tightening is performed in a few strokes, and the power parameters are measured after each impact. 2. The method of tightening control according to claim 1, characterized in that the power parameters are determined by the angle of rotation of the nut for each impact.

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