阅读说明：本技术 一种螺栓的紧固方法 (Fastening method of bolt ) 是由 朱汉华 朱进 于 2019-10-30 设计创作，主要内容包括：本发明公开了一种螺栓的紧固方法,包括根据管线等级图检查螺栓直径和长度的正确性,计算螺栓的伸长量,计算螺栓的受力和计算螺栓的施工扭矩,对螺栓进行拧紧处理,拧紧包括初级拧紧,拧紧完成后,对螺栓进行轻微的松动半圈,额外施加一个预紧力,松半圈的预紧力被消除,对拧紧后的螺栓进行检查；本发明通过先对螺栓的伸长量、螺栓的受力和螺栓的施工扭矩等参数进行计算,根据所得到的参数来选择螺栓拧紧的控制方法,使螺栓的拧紧力矩处于最优状态,能够保证螺栓连接的刚性和紧密性,同时螺栓的防松能力较强,螺栓的使用寿命较长。(The invention discloses a bolt fastening method, which comprises the steps of checking the correctness of the diameter and the length of a bolt according to a pipeline grade chart, calculating the elongation of the bolt, calculating the stress of the bolt and calculating the construction torque of the bolt, tightening the bolt, wherein the tightening comprises primary tightening, slightly loosening the bolt for a half circle after the tightening is finished, additionally applying a pretightening force, eliminating the pretightening force of the loosening half circle, and checking the tightened bolt; according to the invention, parameters such as the elongation of the bolt, the stress of the bolt, the construction torque of the bolt and the like are calculated, and the bolt tightening control method is selected according to the obtained parameters, so that the tightening torque of the bolt is in an optimal state, the rigidity and tightness of bolt connection can be ensured, meanwhile, the anti-loosening capability of the bolt is strong, and the service life of the bolt is long.)

1. A method of fastening a bolt, comprising:

checking the correctness of the diameter and the length of the bolt according to the pipeline grade chart, and calculating the elongation L of the bolt by the following calculation formula:

L＝(K×σ)÷E

in the formula, K is 0.72, E is the elastic modulus, and sigma can be known by looking up a table according to the grade of the bolt;

calculating the stress F of the bolt according to the following calculation formula:

wherein D is D-H, D is the external diameter of the bolt, H is 1.3 XT, and T is the thread pitch;

construction torque T for bolt_cThe calculation is carried out according to the following formula:

Tc＝K×Pc×d

in the formula, K is the average value of the torque coefficient of the bolt connecting pair, Pc is the construction pre-pressure of the bolt, and d is the diameter of the bolt;

tightening the bolt, wherein the tightening comprises primary tightening, after the tightening is finished, slightly loosening the bolt for a half circle, additionally applying a pretightening force, and eliminating the pretightening force of the half circle;

and inspecting the tightened bolt, wherein the inspection method comprises the following steps: drawing a straight line on the end face of the screw rod and the nut, loosening the nut by about 60 degrees, then screwing again through the torque wrench to ensure that the two lines are overlapped, and measuring the torque T at the moment_d，T_dThe calculation formula of (a) is as follows:

T_d＝K×P×d

in the formula, K is a constant, P is a preset value of bolt tension, and d is the diameter of the screw.

2. A method of fastening a bolt according to claim 1, wherein: the control methods of bolt tightening include a torque control method, a torque-rotation angle control method, and a inflection point control method.

3. A method of fastening a bolt according to claim 2, wherein: and selecting one of the three control methods to tighten the bolt according to the parameters of the bolt.

Technical Field

The invention relates to the technical field of bolt fastening, in particular to a bolt fastening method.

Background

A bolt is a mechanical part, and a cylindrical threaded fastener matched with a nut. A fastener consisting of a head part and a screw rod (a cylinder with external threads) needs to be matched with a nut and is used for fastening and connecting two parts with through holes. This form of connection is known as a bolted connection. If the nut is screwed off the bolt, the two parts can be separated, so that the bolt connection belongs to detachable connection.

The bolt connection is one of the most widely applied detachable connections in equipment installation, in order to enhance the rigidity, tightness and anti-loosening capability of the bolt threaded connection and prevent the bolt connection from sliding under transverse load, a plurality of threaded connections need to be pre-tightened during assembly, the pre-tightening force is applied through a certain tightening torque, the proper tightening torque is beneficial to the service life of the bolt connection and a connected part, the connection is failed due to the fact that the tightening torque is too large, particularly in the case of sealing connection, the bolt can be broken, and the residual stress on the surface of a compressed gasket cannot reach the working sealing specific pressure due to the fact that the tightening torque is too small, so that the leakage of a connection system is caused, and how to tighten the bolt is a problem which must be considered in practical production.

Based on this, the present invention has devised a bolt fastening method to solve the above-mentioned problems.

Disclosure of Invention

The present invention is directed to a method for fastening a bolt, which solves the above problems of the related art.

In order to achieve the purpose, the invention provides the following technical scheme: a method of fastening a bolt, comprising:

checking the correctness of the diameter and the length of the bolt according to the pipeline grade chart, and calculating the elongation L of the bolt by the following calculation formula:

L＝(K×σ)÷E

in the formula, K is 0.72, E is the elastic modulus, and sigma can be known by looking up a table according to the grade of the bolt;

calculating the stress F of the bolt according to the following calculation formula:

wherein D is D-H, D is the external diameter of the bolt, H is 1.3 XT, and T is the thread pitch;

construction torque T for bolt_cThe calculation is carried out according to the following formula:

Tc＝K×Pc×d

in the formula, K is the average value of the torque coefficient of the bolt connecting pair, Pc is the construction pre-pressure of the bolt, and d is the diameter of the bolt;

the bolt is screwed, the screwing comprises primary screwing, after the screwing is completed, the bolt is slightly loosened by a half circle, a pretightening force is additionally applied, the pretightening force of the half circle is eliminated, the bolt is in elastic deformation after being screwed, particularly under the conditions of high temperature and vibration load, the long-term continuous pressure can generate creep deformation, the strength of the bolt can be greatly reduced or even loses efficacy after the bolt becomes plastic deformation, the elastic deformation is recovered by retracting the half circle, the pretightening stress is eliminated, and the probability of generating plastic strain and losing efficacy is greatly reduced when the bolt is deformed by the continuous pressure or is in the elastic deformation, so that the bolt can keep the pressure of continuous high strength;

the bolt after being tightened is checked, the torque check is finished after the bolt is finally tightened for 1 hour and before 24 hours, and the checking method comprises the following steps: drawing a straight line on the end face of the screw rod and the nut, loosening the nut by about 60 degrees, then screwing again through the torque wrench to ensure that the two lines are overlapped, and measuring the torque T at the moment_d，T_dThe calculation formula of (a) is as follows:

T_d＝K×P×d

wherein K is constant, P is preset value of bolt tension, and d is screw diameter

Preferably, the bolt tightening control method comprises a torque control method, a torque-rotation angle control method and a yield point control method;

the torque control method is a control method for immediately stopping tightening when the tightening torque reaches a certain set control torque, and is based on a relationship in which the bolt axial preload F is proportional to the tightening torque T applied at the time of tightening when screwing. The relationship between them can be: T-K F. Wherein K is a torque coefficient, the value of the torque coefficient is mainly determined by frictional resistance F mu between contact surfaces and between threads, and in practical application, the value of the K is calculated by a common formula: k ═ 0.161p +0.585 μ d2+0.25 μ (De + Di) where; p is the pitch of the thread; mu is the comprehensive friction coefficient; d2 is the pitch diameter of the thread; de is the effective outer diameter of the bearing surface; di is the design of the inner diameter bolt of the bearing surface and the workpiece, p, d2, De and Di are all determined values, and the value of mu is different according to different processing conditions; the torque control method has the advantages that the control system is simple and direct, the tightening quality can be easily checked by using a torque sensor or a high-precision torque wrench, but the control precision is not high, and the potential of materials cannot be fully utilized;

the torque-angle control method is a control method for screwing a bolt to a small torque and then screwing a specified angle from the moment, and is based on a certain angle, so that the bolt generates a certain axial extension and a connecting piece is compressed, and a certain relation of bolt axial pre-tightening force is generated as a result, when the method is applied for screwing, the purpose of setting initial torque is to screw the bolt or a nut to a tight contact surface, and overcome some initial uneven factors such as surface roughness and the like, and the bolt axial pre-tightening force is mainly obtained in the following angle, the torque-angle control method has the advantages that the bolt axial pre-tightening force precision is high, large axial pre-tightening force can be obtained, and numerical values can be intensively distributed near the average value, but the defect is that a control system is complex, and two parameters of the torque and the angle are required to be measured, the checking of the tightening effect is troublesome;

the yield point control method is a high-precision screwing method developed by utilizing the phenomenon of material yield, and is characterized in that the yield point is determined by continuously calculating and judging the slope of a screwing torque/corner curve, the yield point control method has the advantages that the screwing precision is very high, the precision mainly depends on the yield strength of a bolt, but the defect is that the dynamic and continuous calculation and judgment on the slope of the torque and corner curve are required in the screwing process, and the real-time performance, the operation speed and the like of a control system are high.

And selecting one of the three control methods to tighten the bolt according to the parameters of the bolt.

Compared with the prior art, the invention has the beneficial effects that: according to the invention, parameters such as the elongation of the bolt, the stress of the bolt, the construction torque of the bolt and the like are calculated, and the control method for screwing the bolt is selected according to the obtained parameters, so that the screwing torque of the bolt is in an optimal state, the rigidity and tightness of bolt connection can be ensured, meanwhile, the anti-loosening capability of the bolt is strong, and the service life of the bolt is long.

Detailed Description

The technical solutions in the embodiments of the present invention will be described clearly and completely below, and it should be apparent that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The invention provides a bolt fastening method, which adopts the technical scheme that: a method of fastening a bolt, comprising:

checking the correctness of the diameter and the length of the bolt according to the pipeline grade chart, and calculating the elongation L of the bolt by the following calculation formula:

L＝(K×σ)÷E

in the formula, K is 0.72, E is the elastic modulus, and sigma can be known by looking up a table according to the grade of the bolt;

calculating the stress F of the bolt according to the following calculation formula:

wherein D is D-H, D is the external diameter of the bolt, H is 1.3 XT, and T is the thread pitch;

construction torque T for bolt_cThe calculation is carried out according to the following formula:

Tc＝K×Pc×d

in the formula, K is the average value of the torque coefficient of the bolt connecting pair, Pc is the construction pre-pressure of the bolt, and d is the diameter of the bolt;

the bolt is screwed, the screwing comprises primary screwing, after the screwing is completed, the bolt is slightly loosened by a half circle, a pretightening force is additionally applied, the pretightening force of the half circle is eliminated, the bolt is in elastic deformation after being screwed, particularly under the conditions of high temperature and vibration load, the long-term continuous pressure can generate creep deformation, the strength of the bolt can be greatly reduced or even loses efficacy after the bolt becomes plastic deformation, the elastic deformation is recovered by retracting the half circle, the pretightening stress is eliminated, and the probability of generating plastic strain and losing efficacy is greatly reduced when the bolt is deformed by the continuous pressure or is in the elastic deformation, so that the bolt can keep the pressure of continuous high strength;

the bolt after being tightened is checked, the torque check is finished after the bolt is finally tightened for 1 hour and before 24 hours, and the checking method comprises the following steps: drawing a straight line on the end face of the screw rod and the nut, loosening the nut by about 60 degrees, then screwing again through the torque wrench to ensure that the two lines are overlapped, and measuring the torque T at the moment_d，T_dThe calculation formula of (a) is as follows:

T_d＝K×P×d

wherein K is constant, P is preset value of bolt tension, and d is screw diameter

Preferably, the bolt tightening control method comprises a torque control method, a torque-rotation angle control method and a yield point control method;

the torque control method is a control method for immediately stopping tightening when the tightening torque reaches a certain set control torque, and is based on a relationship in which the bolt axial preload F is proportional to the tightening torque T applied at the time of tightening when screwing. The relationship between them can be: T-K F. Wherein K is a torque coefficient, the value of the torque coefficient is mainly determined by frictional resistance F mu between contact surfaces and between threads, and in practical application, the value of the K is calculated by a common formula: k ═ 0.161p +0.585 μ d2+0.25 μ (De + Di) where; p is the pitch of the thread; mu is the comprehensive friction coefficient; d2 is the pitch diameter of the thread; de is the effective outer diameter of the bearing surface; di is the design of the inner diameter bolt of the bearing surface and the workpiece, p, d2, De and Di are all determined values, and the value of mu is different according to different processing conditions; the torque control method has the advantages that the control system is simple and direct, the tightening quality can be easily checked by using a torque sensor or a high-precision torque wrench, but the control precision is not high, and the potential of materials cannot be fully utilized;

the torque-angle control method is a control method for screwing a bolt to a small torque and then screwing a specified angle from the moment, and is based on a certain angle, so that the bolt generates a certain axial extension and a connecting piece is compressed, and a certain relation of bolt axial pre-tightening force is generated as a result, when the method is applied for screwing, the purpose of setting initial torque is to screw the bolt or a nut to a tight contact surface, and overcome some initial uneven factors such as surface roughness and the like, and the bolt axial pre-tightening force is mainly obtained in the following angle, the torque-angle control method has the advantages that the bolt axial pre-tightening force precision is high, large axial pre-tightening force can be obtained, and numerical values can be intensively distributed near the average value, but the defect is that a control system is complex, and two parameters of the torque and the angle are required to be measured, the checking of the tightening effect is troublesome;

the yield point control method is a high-precision screwing method developed by utilizing the phenomenon of material yield, and is characterized in that the yield point is determined by continuously calculating and judging the slope of a screwing torque/corner curve, the yield point control method has the advantages that the screwing precision is very high, the precision mainly depends on the yield strength of a bolt, but the defect is that the dynamic and continuous calculation and judgment on the slope of the torque and corner curve are required in the screwing process, and the real-time performance, the operation speed and the like of a control system are high.

And selecting one of the three control methods to tighten the bolt according to the parameters of the bolt.

In the description herein, references to the description of "one embodiment," "an example," "a specific example" or the like are intended to mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, a schematic representation of the above terms does not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

The preferred embodiments of the invention disclosed above are intended to be illustrative only. The preferred embodiments are not intended to be exhaustive or to limit the invention to the precise embodiments disclosed. Obviously, many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the invention and the practical application, to thereby enable others skilled in the art to best utilize the invention. The invention is limited only by the claims and their full scope and equivalents.