RU2658103C1 - Method for controling the of tension of high-strength bolts - Google Patents

Abstract

FIELD: method of control.

SUBSTANCE: invention relates to methods for controlling the tension of high strength bolts. Method for controlling the tension of high strength bolts is realized as follows: the bolted joint is assembled in accordance with the current documentation, on the axis of the wrench, the driving part of the control clutch is installed, the leading part of the control clutch through the key element is connected to the driven part of the control clutch, which is connected to the cap nut head, the nut driver creates the torque required to assemble the friction joint, tighten the nut to the bolt until the key element is cut off, by cutting the key element interrupting the tightening of the nut, the limiting torque required for the required tension of the high-strength bolt and the compression of the package of structural elements is controlled.

EFFECT: technical result consists in increasing the accuracy and manufacturability of the assembly of friction joints in the manufacture and installation of span structures and supports of bridge structures, load-bearing structures of high-rise buildings, joints of pipelines and parts of heavy engineering.

1 cl, 2 dwg

Description

The invention relates to methods for controlling the tension of high strength bolts. The method can be used to assemble friction joints in the manufacture and installation of spans and supports of bridge structures, load-bearing structures of high-rise buildings, pipe joints and parts of heavy engineering.

There is a method of controlling the tension of bolts on the design effort, in which the torque for tightening the nut is created by manual traction for the handle of the dynamically operated torque wrench (STP 006-97 Connection of high-strength bolts in steel structures of bridges / Transstroy Corporation, Moscow, 1998 , p. 18, 51-52). The tension control of a high-strength bolt is carried out visually by the indication of a dial type indicator mounted on the key and recording the limit value of the deformation of the key body, determined during calibration and corresponding to the required torque.

The disadvantages of this method are: the complexity of the application associated with the need to apply a force of up to 600 N to the handle of the wrench when creating the required amount of torque; low accuracy of control associated with the remoteness of the measuring device from the employee and the impossibility of reliable visual control of variable readings of a dial indicator; low productivity due to the need, every 4 hours of continuous operation and at least two times per shift, to calibrate manual torque wrenches by means of suspension of control load, which increases labor costs and the duration of assembly work.

There is a method of controlling the tension of bolts on the design effort, in which the torque for tightening the nut is created with a hydraulic torque wrench connected to a pneumatic hydraulic pump (STP 006-97 High-strength bolt connections in steel bridge structures / Transstroy Corporation, Moscow, 1998 , p. 18, 42-51). The tension control of a high-strength bolt is carried out automatically as a result of the actuation of the cutoff torque or manually rotate the valve of the air distributor when visually observing the limit reading of the pump pressure gauge, previously determined during calibration.

The disadvantages of this method are: low productivity, due to the need to calibrate hydraulic torque wrenches, immediately before their first use, after tensioning 1000 and 2000 bolts and then each time after tensioning 5000 bolts, or in the case of replacing such key components as a hydraulic cylinder or chain drum; the complexity of the design of the pneumohydraulic pump, the need to ensure and constant monitoring of the tightness and serviceability of the elements of the pneumohydraulic system.

There is a method in which the torque required to tighten the bolt is created with a torque wrench with a built-in strain gauge bridge (Germany, No. 3804043, G01L 3/00, B25B 23/14, 1989). The key is mounted on a screwed threaded connection and a force is applied to the handle. The required tensioning force of a high-strength bolt is controlled by a strain gauge bridge, from the measuring diagonal of which a signal proportional to the strain of the elastic section of the key handle is fed to the input of the control and measuring device, which carries out the measurement process and provides information about the torque value to a digital indicator. When the required torque value is reached, the tightening is stopped and the key is removed from the tightened threaded connection.

The disadvantage of this method is the complexity of creating the required torque, low productivity due to the need to calibrate the control and measuring device and the unreliability of the method during installation of the structure in a building site.

A known method in which the tension control of a high-strength bolt is carried out by recording the fact of the slow propagation of the crack after tightening the bolt (RU, No. 2560255, G01L 5/24, B25B 23/14, 08/20/2015). In this case, such a phenomenon as acoustic emission is used, i.e. acoustic vibrations occurring in the region of the crack tip during its propagation are recorded. To register acoustic emission signals, a special transducer of acoustic emission signals is installed on the bolted connection before tightening. If the process of delayed propagation of the crack is initiated during the tightening process, then the acoustic emission signals resulting from this can be detected and recognized, and the bolted connection is rejected in a timely manner.

The disadvantages of this method are: the complexity of the equipment for controlling the tension of the bolts by the method of acoustic emission; low control accuracy, since the acoustic emission method, implemented using an acoustic sensor, does not allow you to control the tension of a high-strength bolt, but only fixes the beginning of the destruction process in the material from which the bolts and nuts are made; the need for special training for workers on the use of complex electronic devices for monitoring and diagnosing an acoustic signal.

The closest technical solution to the claimed invention is a method in which the torque is generated by an automatic wrench with a two-element reversing spindle, the outer part of which tightens the nut and the inner bolt (L.I. Gladshtein, V.M. Babushkin, B.F. Kakulia , RV Gafurov High-strength bolts for building steel structures with tension control along the edge of the end element // Transactions of TsNIIPSK named after Melnikov / Industrial and civil engineering, 2008, No. 5, p. 11-13). The tension control of high-strength bolts is performed by cutting the end element located on the bolt of a special design, which is used for the friction joint device.

The disadvantages of this method are: the need to use high strength bolts of non-standard complicated design, requiring increased consumption of high strength steel for their manufacture; complicated wrench design with a two-element reversible spindle; low accuracy of monitoring the tension of the bolt due to the heterogeneity of the stress state in the shear zone of the end element on the bolt.

The objective of the proposed method is to increase the accuracy and manufacturability of the tension control of high-strength bolts.

The technical result is achieved by the fact that in the method of controlling the tension of high-strength bolts, which consists in assembling a bolt connection in accordance with the current documentation, a torque is created with a wrench to tighten the nut until the required tension force is created in the bolt, and a control torque is used to transmit torque coupling with a key element, the leading part of the control coupling is installed on the axis of the wrench, the leading part of the control coupling is connected to the follower through the key element part of the control sleeve, which is connected to the cap nut head, tightening the nut on the bolt to cut keyway element for shear keying element interrupting tightening nuts, tightening torque limit control required for the desired high tension bolts and compression of the cell stack structure.

The essence of the proposed method is illustrated by drawings, where in FIG. 1 shows a control sleeve with a key element, and FIG. 2 shows a cross-sectional view of a control sleeve over a section passing through a key element.

The method of controlling the tension of high-strength bolts is implemented as follows: assemble the bolt connection in accordance with the current documentation, install the leading part of the control coupling 2 on the axis of the screwdriver 1, the leading part of the control coupling 2 through the key element 3 are connected to the driven part of the control coupling 4, which is connected to the coupling with a wrench 5, a wrench create the torque necessary to assemble the friction joint, tighten the nut 6 onto the bolt 7 until the key element 3 is cut, along the key element 3, interrupting the tightening of the nut 6, control the ultimate torque required for the required tension of the high-strength bolt 7 and compression of the package of structural elements 8 through washers 9 and 10.

Improving the accuracy of the proposed method for controlling the tension of high-strength bolts in comparison with the prototype is achieved by the existence of an experimentally established dependence of the calculated steel shear resistance on the yield strength of steel (paragraph 8.8, table 8.3, SP 35.13330.2011 "Bridges and pipes"):

R _s = 0.58 R _yn / γ _m , where

R _s is the calculated steel shear resistance;

R _yn is the yield strength of steel;

γ _m - 1,025 - material reliability coefficient for steel grade St3 (Clause 8.8, Table 8.4, SP 35.13330.2011 “Bridges and pipes”),

as well as on a certain dependence of the force cutting off the key element, on the torque created to tighten the nut:

P = M / z, where

P is the force cutting off the key element;

M is the limit value of the torque created to tighten the nut;

z is the distance from the axis of rotation of the spindle of the wrench 1 to the cut plane of the key element 3 (Fig. 2).

The destruction of the material of the key element 3 occurs when the limit value of the shear stresses in the plane of the shear of the key on the cylindrical surface of the contact leading 2 and 4 driven elements of the control coupling is reached. The limit value of tangential stresses is reached at a time along the entire length of the key element 3 and leads to its cutting and the cessation of the transmission of torque from the axis of the wrench to the nut 6.

Improving the manufacturability of the proposed method for controlling the tension of high-strength bolts in comparison with the prototype consists in the absence of the need to manufacture bolts of non-standard design and the possibility of using standard high-strength bolts, nuts, washers and union nut heads for friction joints.

Claims (1)

The method of controlling the tension of high-strength bolts, which consists in collecting the bolt connection in accordance with the current documentation, using a wrench to create the torque necessary to tighten the nut until the required tension force is created in the bolt, characterized in that a control clutch with a key is used to transmit torque element, the leading part of the control coupling is installed on the axis of the wrench, the leading part of the control coupling is connected through the key element to the driven part of the control coupling s, which is connected to the cap nut head, tightening the nut on the bolt to cut keyway element for shear keying element interrupting tightening nuts, tightening torque limit control required for the desired high tension bolts and compression of the cell stack structure.

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