CN113565850B - Non-unbalance-load constant-tension accurate fastening method - Google Patents
Non-unbalance-load constant-tension accurate fastening method Download PDFInfo
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- CN113565850B CN113565850B CN202110748778.0A CN202110748778A CN113565850B CN 113565850 B CN113565850 B CN 113565850B CN 202110748778 A CN202110748778 A CN 202110748778A CN 113565850 B CN113565850 B CN 113565850B
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- 238000013461 design Methods 0.000 claims description 20
- 238000006243 chemical reaction Methods 0.000 claims description 19
- 238000007789 sealing Methods 0.000 claims description 16
- 230000003068 static effect Effects 0.000 claims description 7
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- 230000002349 favourable effect Effects 0.000 description 4
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16B—DEVICES FOR FASTENING OR SECURING CONSTRUCTIONAL ELEMENTS OR MACHINE PARTS TOGETHER, e.g. NAILS, BOLTS, CIRCLIPS, CLAMPS, CLIPS OR WEDGES; JOINTS OR JOINTING
- F16B31/00—Screwed connections specially modified in view of tensile load; Break-bolts
- F16B31/02—Screwed connections specially modified in view of tensile load; Break-bolts for indicating the attainment of a particular tensile load or limiting tensile load
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L5/00—Apparatus for, or methods of, measuring force, work, mechanical power, or torque, specially adapted for specific purposes
- G01L5/24—Apparatus for, or methods of, measuring force, work, mechanical power, or torque, specially adapted for specific purposes for determining value of torque or twisting moment for tightening a nut or other member which is similarly stressed
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
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Abstract
The invention relates to an unbalance-load-free constant-tension accurate fastening method, which comprises the following steps of 1, calculating the pre-tightening force required by a stud, and selecting a constant-tension bolt pair; step 2, performing quality inspection and acceptance on the selected constant tension bolt pair; step 3, selecting a fastening tool with constant tension; step 4, constructing a test system; step 5, fastening the constant tension bolt pair by using the selected constant tension fastening tool, acquiring tension born by the stud, torque and control parameters of the constant tension fastening tool through a test system, recording the torque at the moment and taking the torque as construction torque, and recording the control parameters of the constant tension fastening tool at the moment and taking the control parameters as construction control parameters when the tension is equal to the pre-tightening force required by the bolt pair; step 6, fastening the fastened piece by using the determined construction torque and the construction control parameters on a construction site; the method can reduce the error of the pre-tightening force of the bolt pair to +/-1.5 percent, thereby obviously improving the pre-tightening force precision of the bolt pair.
Description
Technical Field
The invention relates to the technical field of fastening, in particular to an unbalance-load-free constant-tension accurate fastening method.
Background
The fastening connection of the bolt pair is one of the most widely applied detachable connection methods in mechanical assembly and equipment installation in various industries such as petrochemical industry, electric power, railway and the like, and flange connection sealing; the current commonly used fastening tools comprise a hydraulic torque wrench, a pneumatic torque wrench, an electric torque wrench, a manual torque wrench and the like; in order to enhance the rigidity, tightness and anti-loosening capability of the bolt pair connection and prevent the bolt pair from being subjected to transverse load, the bolt pair needs to be pre-tightened during assembly operation; the bolt pair usually fails due to overlarge tightening torque of the bolt pair, particularly, under the condition of sealing connection, the sealing gasket is crushed to lose elasticity and even break the sealing gasket, and the residual pressing force on the surface of the pressed gasket cannot reach the working sealing specific pressure due to the undersize pre-tightening torque, so that the leakage of a connection system is caused.
In the prior art, there are two common methods for controlling the pre-tightening force of a bolt pair, the first method is to use a tensioner (or called bolt pair tensioner) to fasten the bolt pair, and the second method is to control the pre-tightening force of the bolt pair by limiting the tightening torque, i.e. fixed torque fastening, wherein,
in the first method, a bolt pair is fastened by using a tensioner, the stud is stretched by using the tensioner according to a given pretightening force and a stretching force equal to or greater than the pretightening force, so that the nut can be freely screwed to a set position under the condition of no load, then the oil pressure of the tensioner is reduced, the stud can be contracted under the action of self-resilience force, a fastener and a gasket are pressed, and the aim of controlling the pretightening force of the bolt pair is achieved, but in practical application, two main problems exist in the method: (1) the efficiency is very low, and the method is generally only used for fastening a large-size bolt pair. (2) The elasticity of the stud is high when the stud is used for the first time, and the pre-tightening force cannot reach a required design value due to the deformation of the stud, the failure of resilience force and the like of the stud which is detached and installed again after the stud is used, so that the error is large, and the problem that the pre-tightening force of a bolt pair cannot be accurately controlled exists.
In the second method, the pretightening force of the bolt pair is controlled by limiting the tightening torque, and the main principle is to calculate the required tightening torque through the pretightening force, and the conversion formula between the pretightening force and the pretightening force is as follows:
Ts=KFd
in the formula: ts-tightening torque, N.m;
k is the torque coefficient;
d-nominal diameter of the thread, mm;
f, pre-tightening force, which is 70-80% of the maximum drawing force of the stud.
Therefore, in practical application, before the construction unit carries out site construction, the construction unit can calculate according to the formula to obtain the corresponding tightening torque, and when the construction is carried out, the tightening torque is applied to the bolt pair through the fastening tool to generate the corresponding pretightening force, so that the pretightening force of the stud can reach the required pretightening force theoretically.
However, in practical application, the method has the problem that the pretightening force cannot be accurately controlled; the main reason is that in the formula, F is the tensile force value to be achieved by the stud and is a design value; d is the nominal diameter of the thread and is a fixed value after the design and the model selection; and K in the formula is an empirical value obtained by looking up a table; in practice, the material, machining precision, friction coefficient, whether lubricant is added, the selected fastening tool, the size of the acting force arm and the reaction force arm and other factors of the fastening tool have great influence on the K value, so that the accurate value of the K value cannot be given in actual operation, the calculated tightening torque has large error, the tightening torque is controlled to have large error, the actual value of the pre-tightening force of the bolt pair has large discreteness, the aim of accurately controlling the pre-tightening force cannot be achieved, the error is generally about +/-25%, and the maximum error even can reach +/-40%.
As can be seen from the above analysis, the existing bolt pair fastening methods all have a problem that the pretightening force cannot be precisely controlled, and although some bolt pair fastening methods and/or apparatuses are disclosed in the prior art, for example, a method for coaxially mounting a fastener acting force and a reaction arm is disclosed in chinese patent CN 105269504 a, the problem of unbalance loading existing in the bolt pair fastening process can be effectively solved, which is beneficial to improving the pretightening force accuracy (since the unbalance loading also affects the pretightening force accuracy), but 4 main problems still exist: (1) calculating to obtain the torque required by the torque not conforming to the actual pretightening force; (2) the size of the nut is the same as that of the washer, the tool is easy to block, the dismounting tool needs to be reversed, the pre-tightening force of the bolt pair is relieved (3), and the follow-up rotation of the stud is influenced by the design that the nut on the non-fastening operation side is not prevented from rotating; (4) the tooth-shaped structure of the washer can only increase the friction force, and the actual pretightening force of the bolt pair cannot be accurately controlled due to the reason that the rotation is likely to occur when the torque is too large, so that how to accurately control the pretightening force of the bolt pair needs to be solved urgently.
Disclosure of Invention
The invention provides a fastening method capable of obviously improving the pre-tightening force precision of a bolt pair, aiming at solving the problem that the deviation between the actual pre-tightening force value and the design value of the bolt pair is larger because the pre-tightening force of the bolt pair cannot be accurately controlled in the prior art, and the main concept is as follows:
an accurate fastening method without unbalance loading and constant tension comprises the following steps:
step 1, calculating the required pre-tightening force of a bolt pair according to relevant standards and specifications of a flange sealing gasket, and selecting a constant tension bolt pair with corresponding specification grades, wherein the constant tension bolt pair comprises a stud, an occlusion nut, an occlusion washer and a nut, the bolt pair comprises a stud, and one end of the occlusion nut and one end of the occlusion washer are respectively provided with occlusion teeth;
step 2, performing quality inspection and acceptance on the selected constant tension bolt pair according to relevant standards and specifications;
step 3, selecting a constant-tension fastening tool meeting the requirements of a fastening operation environment;
step 4, constructing a test system, and installing the selected constant tension bolt pair to the test system;
step 5, fastening operation is carried out on the constant tension bolt pair on the test system by using the selected constant tension fastening tool, in the fastening process, data such as tension born by the stud, torque and control parameters of the constant tension fastening tool and the like are collected by the test system, and at least when the tension is equal to the required pre-tightening force of the bolt pair, the torque born by the bolt pair at the moment is recorded and is used as construction torque, and the control parameters of the constant tension fastening tool at the moment are recorded and are used as construction control parameters to compile a construction scheme;
and 6, selecting the constant tension bolt pair in the step 1, selecting the constant tension fastening tool in the step 3, and fastening the fastened piece by using the construction torque and the construction control parameters determined in the step 5 on the construction site. By adopting the method, the torque born by the stud when the required bolt pair pre-tightening force value is reached can be accurately determined by a test system before construction, namely in the method, the construction torque and the construction control parameters corresponding to the bolt pair pre-tightening force value are real data tested by the test system according to design requirements and actual fastening operation conditions, but are not calculated by adopting an empirical formula, so that in a construction site, the pre-tightening force of each stud can be accurately controlled by only utilizing the selected constant tension bolt pair and the constant tension fastening tool and utilizing the construction torque and the construction control parameters determined by the test, the precision of the pre-tightening force of the bolt pair can be effectively improved, the error is reduced, the error is usually only about +/-1.5 percent, the defects in the prior art are effectively solved, and the operation is simple and convenient, in addition, the method can accurately control the pretightening force of the bolt pair, can prevent the problems that the deviation of an actual value and a theoretical value is large due to insufficient and uneven pretightening force precision, further the leakage of the connection is not firm at a sealing part, or the fastening piece is damaged due to overlarge pretightening force, and the like, thereby being beneficial to more firm connection of the fastening piece, effectively preventing the problems of loose connection, damage and the like and prolonging the service life.
Preferably, the control parameters include air pressure, hydraulic pressure and/or electric current.
Preferably, in step 1, the bolt pair pretension force is calculated according to design requirements, process parameters, relevant design criteria and/or design specifications.
In order to solve the problem of improving the reliability of the method in the second aspect of the present invention, it is preferable that the above-mentioned step 4 to step 5 are repeatedly performed three times or more; if the test values obtained by three or more tests meet the technical requirements, compiling a construction scheme according to the test values;
if the test values obtained by three or more tests do not meet the technical requirements, after finding out reasons and correcting, re-executing the steps 4-5 for three or more times, and compiling a construction scheme according to the test values until the obtained test values all meet the technical requirements;
the test values include the construction torque and construction control parameters. By repeatedly executing the steps 4-5 at least three times, accidental factors can be effectively avoided, and the reliability of the bolt pair fastened by the method can be effectively improved.
In order to solve the unbalance loading problem in the bolt pair fastening process in the third aspect of the present invention, preferably, the test system constructed in step 4 includes a test platform, a flange one, a constant tension fastening tool, a tension collector, a data processor and a display, wherein,
the test platform comprises a base and a second flange constructed on the base; the constant-tension fastening tool comprises a fixed end and a power end which are coaxial, the shape of an opening at the lower side of the fixed end is matched with the outer contour of the meshing washer, and the fixed end is used for locking the meshing washer to generate a constant-moment reaction arm; the power end is in clearance fit with the fixed end, the shape of an opening at the lower side of the power end is matched with the outer contour of a nut in the constant-tension bolt pair, and the power end is used for driving the nut to rotate under the action of a constant-tension fastening tool; the fixed end does not rotate along with the power end and keeps static relative to the fastened piece; the constant tension fastening tool, the tension collector and the display are respectively connected with the data processor, and the tension collector is used for collecting tension born by the stud in the stud fastening process;
the constant tension bolt pair is characterized in that a stud in the constant tension bolt pair sequentially penetrates through the meshing nut, the first flange, the tension collector, the second flange, the meshing washer and a nut in the constant tension bolt pair, one end of the meshing nut, which is provided with meshing teeth, contacts the first flange, one end of the meshing washer, which is provided with meshing teeth, contacts the second flange, the power end and the fixed end are respectively sleeved on the nut and the meshing washer, and the constant tension fastening tool is used for driving the power end to rotate. In the scheme, an occlusion nut, a first flange, a tension collector, a second flange, an occlusion washer and a nut are concentrically connected through a stud in a constant tension bolt pair, and one end of the occlusion nut, which is provided with occlusion teeth, is in contact with the first flange, so that the occlusion nut generates occlusion force under the action of rotation and tension to bite the surface of the first flange and keeps a relatively static state with the first flange; meanwhile, one end of the meshing washer, which is provided with meshing teeth, is in contact with the second flange, so that in the fastening process, a fastening tool with constant tension acts on the nut through the power end to rotatably screw the nut, meanwhile, the fixed end acts on the meshing washer to generate a reaction force, the meshing washer generates a meshing force under the combined action of the reaction moment and the tension, the meshing force is increased along with the increase of the torsion moment and the pressure to form the reaction force, and at the moment, the meshing washer, the fixed end and the second flange are in a relative static state; in the process, the action torque is constant, the length of the action force arm is the radius of the nut, the length of the reaction force arm is the radius of the occlusion washer, and the radius of the nut and the radius of the occlusion washer are fixed and have the same axis, so that the action torque is equal to the reaction torque, the unbalance loading problem existing in the fastening process of the bolt pair can be effectively solved, the fastening precision is further improved, and the pre-tightening force is more accurately controlled; in the fastening process, the tension collector can collect the tension born by the bolt pair in the stud fastening process and transmit the tension to the data processor, and the torque and the control parameters of the constant tension fastening tool can also be transmitted to the data processor for recording and displaying through the display.
In order to solve the problem of uneven stress in the process of fastening the flange by using the method in the fourth aspect of the present invention, further, in the step 6, the fastened piece is a flange, the step 6 further includes a method of fastening the flange, and the method of fastening the flange includes the following steps:
(1) at least four positioning pins penetrate through flange holes of two flanges to be fastened, and the positioning pins are uniformly distributed along the circumferential direction of the flanges respectively so that the two flanges are aligned;
(2) arranging the constant tension bolt pair at the rest flange hole, wherein the stud penetrates through the flange hole, the snap nut is sleeved at one end of the stud, and one end of the snap nut, which is provided with snap teeth, is in contact with the flange; the meshing gasket is sleeved at the other end of the stud, and one end of the meshing gasket, which is provided with meshing teeth, is in contact with the flange;
(3) adopting the selected fastening tool with constant tension, and setting the torque value to be 50% of the construction torque; and synchronously fastening each constant tension bolt pair up and down and left and right to reach the set torsion value; in the operation fastening process, when the constant-tension fastening tool reaches a set value, the tool automatically stops working;
(4) removing the positioning pin, arranging a constant tension bolt pair in the flange hole of the removed positioning pin in the mode of the step (2), and fastening the constant tension bolt pair in the mode of the step (3);
(5) setting the torque value in the constant tension fastening tool as 80% of the construction torque, and sequentially fastening each constant tension bolt pair along the opposite angle by using the constant tension fastening tool;
(6) the torque value in the constant tension fastening tool is set to 100% of the construction torque, and the constant tension bolt pairs are fastened in sequence diagonally by the constant tension fastening tool. In the scheme, the number of the flange holes on the two connected flanges is usually more than four, for example, eight flanges and the like are adopted, and the two flanges are positioned by using the positioning pins, so that the two flanges are aligned, the studs can be favorably inserted into the rest flange holes, and the two flanges can be favorably in surface-to-surface contact, so that the problems of accurately aligning and positioning the two flanges are solved; in the process of fastening the constant tension bolt pairs, three torque value values which are sequentially increased are adopted to pre-fasten each constant tension bolt pair in stages, in the first stage, each constant tension bolt pair is pre-fastened synchronously according to 50% of the determined construction torque by using a constant tension fastening tool, and each constant tension bolt pair is fastened synchronously according to an upper direction, a lower direction and a left direction, so that each constant tension bolt pair can be fastened gradually, flanges can be closed in parallel in the fastening process, more uniform stress is facilitated, and the offset moment can be effectively reduced or even eliminated; the torque value of the constant tension fastening tool is gradually increased in the second stage and the third stage, and the constant tension bolt pairs are fastened in sequence along opposite angles, so that the stress of the flange and the constant tension bolt pairs in the fastening process is more uniform, and the pretightening force of the constant tension bolt pairs can be accurately controlled so as to meet the design requirement.
Furthermore, in the step (3) and/or the step (4), the number of the adopted constant-tension fastening tools is one or more, so that multi-synchronous fastening is realized. In the scheme, one pair of constant-tension fastening tools can respectively act on two studs at the opposite angle of the same flange, the other pair of constant-tension fastening tools can respectively act on two studs at the other opposite angle of the flange, and the one pair or the two pairs of constant-tension fastening tools are controlled to synchronously act, so that the uniform stress is favorably applied to the fastening process of the flange, and the parallel closing of the two flanges is more favorably realized.
In a further scheme, the method further comprises the step (7) of sequentially fastening each constant tension bolt pair according to the construction torque and the construction control parameters by using the constant tension fastening tool. The fastened constant tension bolt pair can be calibrated through the step, namely, the constant tension bolt pair is fastened by using a constant tension fastening tool according to 100% of construction parameters, and all the constant tension bolt pairs can accurately reach the set pretightening force.
Preferably, the constant tension fastening tool may be an electric wrench, a hydraulic wrench, or a pneumatic wrench.
Compared with the prior art, the method for accurately fastening the constant tension without unbalance loading provided by the invention has the advantages that the tightening torque is real data tested by a test system according to design requirements and actual fastening operation conditions, and is not calculated by an empirical formula, so that the pre-tightening force of each bolt pair can be accurately controlled only by using a selected constant tension bolt pair and a constant tension fastening tool and performing fastening operation by using construction torque and construction control parameters determined by tests on a construction site, the phenomenon of 'connecting shaft rotation' of the bolt pair in the fastening process is avoided, the accuracy of the pre-tightening force of the bolt pair can be effectively improved, the error is reduced, the error is usually only about +/-1.5%, the defects in the prior art are effectively overcome, the operation is simple and convenient, the construction efficiency is high, and the method is convenient to widely popularize and apply, the method is particularly suitable for occasions with higher requirements on the fastening standard of the bolt pair.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present invention and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained according to the drawings without inventive efforts.
Fig. 1 is a flowchart of a method for accurately fastening with constant tension without unbalanced loading according to embodiment 1 of the present invention.
Fig. 2 is a schematic structural diagram of a method for accurately fastening a constant tension without an unbalanced load according to an embodiment 1 of the present invention, in which a test system is used to measure a construction torque and a construction control parameter.
Fig. 3 is a partial structural view of a constant tension fastening tool.
Fig. 4 is a front view of a flange.
Fig. 5 is a schematic view of the method for fastening with constant tension and without unbalanced loading according to embodiment 1 of the present invention, after aligning two flanges with at least four positioning pins in step (1).
Fig. 6 is a schematic diagram of the method for accurately fastening with constant tension without unbalanced loading according to embodiment 1 of the present invention, in step (2), after the constant tension bolt pairs are disposed in the remaining flange holes.
Fig. 7 is a schematic diagram of the method for accurately fastening with constant tension without unbalanced loading provided in embodiment 1 of the present invention, in step (4), after the locating pin is removed and the constant tension bolt pair is disposed in the flange hole of the removed locating pin.
Fig. 8 is a cross-sectional view of a flange with a constant tension bolt pair according to an unbiased load constant tension precise fastening method provided in embodiment 1 of the present invention.
Fig. 9 is a cross-sectional view of a constant tension bolt pair tightened by a constant tension tightening tool according to an unbiased load constant tension precise tightening method provided in embodiment 1 of the present invention.
Description of the drawings
Constant tension fastening tool 200, fixed end 201 and power end 202
And a positioning pin 500.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. The components of embodiments of the present invention generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations. Thus, the following detailed description of the embodiments of the present invention, presented in the figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments of the present invention without making any creative effort, shall fall within the protection scope of the present invention.
Example 1
Referring to fig. 1 and 2, the present embodiment provides an accurate fastening method with constant tension without unbalanced loading, which includes the following steps:
step 1, calculating the required pre-tightening force of the bolt pair according to the relevant national standards and specifications and the specifications of a flange sealing gasket, and selecting a constant tension bolt pair with a corresponding specification grade, namely selecting a constant tension bolt pair meeting the requirements of strength and rigidity;
in this embodiment, the country-related standard and specification may be a country-related standard and specification in the field, for example, the country-related standard and specification may be GB/T16823.3-2010, GB/T6170-2015, SH/T3404-2013, and/or GB/T16823.3-2010, etc.; the flange sealing gasket specification can be JB/T4718-92, JB/T4719-92, JB/T4720-92 and/or gb/T29463.2-2012 and the like, and is not illustrated herein.
In the present embodiment, the constant tension bolt pair includes a stud 101, a snap nut 102, a snap washer 103 and a nut 104, when one end of the stud 101 is configured with a nut, the stud 101 may also be replaced with a bolt, the bolt is not provided with the nut 104, and one ends of the snap nut 102 and the snap washer 103 are respectively configured with snap teeth, in the present embodiment, the snap teeth are distributed radially, and preferably, the snap teeth are uniformly distributed along the circumferential direction of the snap nut 102 and the snap washer 103;
by way of example, in actual operation, the bolt pair pretension may be calculated according to design requirements, process parameters, relevant design criteria, and/or design specifications.
Step 2, performing quality inspection and acceptance on the selected constant tension bolt pair according to relevant national standards and specifications; because the constant tension bolt pairs of various models have corresponding national or industrial standards and specifications, the quality inspection and acceptance can be carried out according to the standards and specifications specified by the country or industry;
it is understood that, in the embodiment, the country-related standards and specifications may be GB/T16823.3-2010, GB/T6170-2015, SH/T3404-2013 and/or GB/T16823.3-2010, etc., which are not illustrated one by one here.
Step 3, selecting a constant-tension fastening tool meeting the fastening operation environment requirement; preferably, the constant tension fastening tool may be an electric wrench, a hydraulic wrench, a pneumatic wrench, or the like, which is commonly used in the art.
Step 4, constructing a test system as shown in fig. 2, and installing the selected constant tension bolt pair to the test system; so as to simulate the fastening process of the constant tension bolt pair in a laboratory by a test system in advance.
Step 5, performing fastening operation on the constant tension bolt pair on the test system by using the constant tension fastening tool selected in the step 3, as shown in fig. 2, acquiring the tension (namely the actual pre-tightening force of the stud), the torque of the constant tension fastening tool and related control parameters (the control parameters comprise hydraulic pressure, air pressure and/or current and the like) born by the stud 101 through the test system in the fastening process, recording the corresponding torque at the moment and taking the torque as the construction torque, and recording the control parameters of the constant tension fastening tool at the moment and taking the control parameters as the construction control parameters when the tension is equal to the required pre-tightening force of the bolt pair; during subsequent construction, the aim of accurately controlling the pretightening force can be achieved by controlling the construction torque and the construction control parameters.
And 6, selecting the constant tension bolt pair in the step 1, selecting the constant tension fastening tool in the step 3, and fastening the fastened piece by using the construction torque and the construction control parameters determined in the step 5 on the construction site.
Specifically, by adopting the method, the torque born by the nut 104 when the required bolt pair pretension value is reached can be accurately determined by a test system before construction, namely in the method, the construction torque and the construction control parameters corresponding to the bolt pair pretension value are real data tested by the test system according to design requirements and actual fastening operation conditions, but are not calculated by adopting an empirical formula, so that in a construction site, the pretension force of each stud can be accurately controlled only by using the selected constant-tension bolt pair and the constant-tension fastening tool and by using the construction torque and the construction control parameters determined by the test, the precision of the pretension force of the bolt pair can be effectively improved, the error is reduced, the error is usually only about +/-1.5 percent, and the defects in the prior art are effectively solved, in addition, the method can accurately control the pretightening force of the bolt pair, can prevent the large deviation of an actual value and a theoretical value caused by insufficient and uneven pretightening force precision, further causes the problems of leakage at a sealing part due to loose connection, flange sealing gasket and the like caused by the unstable connection or damage of the fastening piece, the flange sealing gasket and the like due to the overlarge pretightening force, is favorable for more firm connection of the fastening piece, can effectively prevent the problems of loose connection, damage and the like, and is favorable for prolonging the service life.
In order to improve the reliability of the method, the method can repeatedly execute the steps 4-5 for three times or more in the actual operation process; if the test values obtained by three or more tests (the test values comprise the construction torque and the construction control parameters) all meet the technical requirements, a construction scheme can be compiled according to the test values; in a more preferable scheme, the construction torque can be an average value of torques acquired by a plurality of tests;
if the test values obtained by three or more tests do not meet the technical requirements, the reason needs to be found out firstly, and after the reason is overcome or corrected, the steps 4-5 are executed for three or more times again, and the construction scheme can not be compiled according to the test values until the obtained test values all meet the technical requirements; and a formal construction scheme is issued after signature confirmation by testers and technicians, and a construction unit can execute the construction scheme.
It can be understood that, in this embodiment, by repeatedly performing the steps 4 to 5 at least three times, accidental factors in the test process can be effectively avoided, so that the reliability of fastening the bolt pair by using the method can be effectively improved.
In the prior art, although a hydraulic torque wrench, a pneumatic torque wrench or a manual torque wrench has a controllable torque function, due to the existence of an action force arm and a reaction force arm and the length of the action force arm and the reaction force arm are changed, the action force arm and the reaction force arm are not coaxial with the central line of a stud 101, a lateral force, namely an unbalance load, is generated on the stud 101 in the fastening process, the loaded torque cannot be effectively converted into a tensile force, the pre-tightening force cannot meet the design requirement after fastening, the pre-tightening force error of each bolt pair is large (about > +/-25%), and the fastened piece is not closed uniformly due to different stress, so that equipment failure, leakage and other safety accidents are caused; to solve this problem, in the present embodiment, the testing system constructed in step 4 includes a testing platform, a flange one 303, a constant tension fastening tool 200, a tension collector 304, a data processor and a display 306, wherein,
as shown in fig. 2, the test platform comprises a base 301 and a second flange 302 configured on the base 301; the constant-tension fastening tool 200 comprises a fixed end 201 and a power end 202 which are coaxial, as shown in fig. 3, the lower opening shape of the fixed end 201 is matched with the outer contour of the snap washer 103, and the fixed end 201 is used for locking the snap washer 103 to generate a constant-torque reaction arm; the power end 202 is in clearance fit with the fixed end 201, the shape of an opening at the lower side of the power end 202 is matched with the outer contour of the nut 104 in the constant-tension bolt pair, the power end 202 is used for driving the nut 104 to rotate under the action of a constant-tension fastening tool, and in the process, the fixed end 201 does not rotate along with the rotation of the power end 202, namely, the fixed end 201 and the fixed end can rotate relatively;
as shown in fig. 2, in this embodiment, the constant tension fastening tool, the tension collector 304, and the display 306 are respectively connected to the data processor, the tension collector 304 is configured to collect tension borne by the stud 101 during fastening of the bolt pair, and all of the applied torque, related control parameters, and the like of the constant tension fastening tool may be transmitted to the data processor, and the data processor may adopt a data processing device 305 commonly used in the prior art, for example, a PC, a single chip microcomputer, a universal tester, and the like, and be configured to process and record the collected data, and may record and draw a stress-strain curve, a tension change curve, and the like of the bolt pair, and may display the stress-strain curve, the tension change curve, and the like through the display 306, so that a user can view the data more intuitively.
In this embodiment, the assembly manner of the constant tension bolt pair on the test platform is as shown in fig. 2, a stud 101 in the constant tension bolt pair sequentially passes through the snap nut 102, a first flange 303, a tension collector 304, a second flange 302, a snap washer 103 and a nut 104, one end of the snap nut 102, which is provided with snap teeth, contacts the first flange 303, as shown in fig. 2, one end of the snap washer 103, which is provided with snap teeth, contacts the second flange 302, the power end 202 and the fixed end 201 are respectively sleeved on the nut 104 and the snap washer 103, and the constant tension fastening tool is used for driving the power end 202 to rotate; as shown in fig. 2, in the present embodiment, the tension collector 304 may preferably adopt a hollow disc-shaped structure so as to be installed between the second flange 302 and the first flange 303; specifically, in the embodiment, the snap nut 102, the first flange 303, the tension collector 304, the second flange 302, the snap washer 103 and the nut are concentrically connected through the stud 101 in the constant tension bolt pair, and one end of the snap nut 102, which is configured with snap teeth, contacts the first flange 303, so that the snap nut 102 generates a snap force under the action of rotation and tension to snap the surface of the first flange 303 and keeps a relatively static state with the first flange 303; meanwhile, one end of the snap washer 103, which is provided with snap teeth, contacts the second flange 302, so that in the fastening process, a constant-tension fastening tool acts on the nut 104 through the power end 202 to rotatably tighten the nut 104, meanwhile, the fixed end 201 acts on the snap washer 103 to generate a reaction force, the snap washer 103 generates a snap force under the combined action of a reaction torque and a tension force, the snap force is increased along with the increase of the torque and the pressure, and the reaction force is formed, and at the moment, the snap washer 103, the fixed end 201 and the second flange 302 are in a relative static state; in the process, the action torque is constant, the length of the action force arm is the radius of the nut, the length of the reaction force arm is the radius of the meshing washer 103, and the radius of the nut 104 is equivalent to the radius of the meshing washer 103, so that the action torque is equal to the reaction torque, the unbalance loading problem existing in the fastening process of the bolt pair can be effectively solved, the fastening precision is further improved, and the pre-tightening force is more accurately controlled; in the fastening process, the tension collector 304 can collect the tension born by the bolt pair in the fastening process of the bolt pair and transmit the tension to the data processor, and the torque and the control parameters of the constant tension fastening tool can also be transmitted to the data processor and displayed through the display 306.
In a further aspect, to solve the problem of uneven stress during fastening the flanges by using the method, in step 6, the fastened member is a flange 400, as shown in fig. 4, the number of flange holes on two flanges 400 to be connected is generally greater than four, for convenience of description, as shown in fig. 4, in this embodiment, the number of flange holes on the flange is 12, and each flange hole has a number, such as flange hole one 401, flange hole two 402 … …, and flange hole twelve 412, as shown in fig. 4;
in this embodiment, the step 6 further includes a method of fastening a flange, the method of fastening a flange includes the steps of:
step (1), at least four positioning pins 500 penetrate through flange holes of two flanges 400 to be fastened, and the positioning pins 500 are respectively and uniformly distributed along the circumferential direction of the flanges, so that the two flanges are aligned, as shown in fig. 5; utilize locating pin 500 to fix a position two flanges, can be so that two flanges adjust well, both be favorable to penetrating double-screw bolt 101 in remaining flange hole, be favorable to two flanges to form face-to-face contact again to solve the problem of accurate alignment and two flanges of location.
Step (2) arranging the constant tension bolt pairs at the remaining flange holes, as shown in fig. 6, 8 and 9, wherein the stud 101 passes through the flange holes, the snap nut 102 is sleeved at one end of the stud 101, and one end of the snap nut 102, which is provided with snap teeth, is in contact with the flange; the snap washer 103 is sleeved at the other end of the stud 101, and one end of the snap washer 103, which is provided with snap teeth, is in contact with the flange; therefore, the problems of 'connecting shaft rotation', unbalance loading and the like in the bolt pair fastening process are effectively solved (the specific principle is as above, and the details are not repeated here), the fastening precision is further improved, and the pretightening force is controlled more accurately.
Step (3) adopting the selected constant tension fastening tool 200, and setting a torque value to be 50% of the construction torque (namely, in the process of operating and fastening, the constant tension fastening tool automatically stops working when reaching a set value); and synchronously fastening each constant tension bolt pair up and down and left and right to reach the set torsion value; for example, as shown in fig. 5 and fig. 6, the constant tension bolt pairs at the first flange hole twelve 412 and the second flange hole six 406 (i.e., the constant tension bolt pairs at the upper and lower positions) may be simultaneously tightened by 50% of the construction torque, the constant tension bolt pairs at the third flange hole 403 and the ninth flange hole 409 (i.e., the constant tension bolt pairs at the left and right positions) may be synchronously tightened by 50% of the construction torque, and then the constant tension bolt pairs at the remaining flange holes may be continuously tightened in the same manner in the clockwise or counterclockwise direction, for example, the constant tension bolt pairs at the first flange hole 401 and the seventh flange hole 407 may be continuously synchronously tightened by 50% of the construction torque, and then the constant tension bolt pairs at the fourth flange hole 404 and the tenth flange hole 410 may be continuously tightened by 50% of the construction torque.
Step (4) removing the positioning pin 500, arranging a constant tension bolt pair in the flange hole of the removed positioning pin 500 in the manner of step (2), and fastening the constant tension bolt pair in the manner of step (3), as shown in fig. 7;
step (5) setting the torque value in the constant tension fastening tool as 80% of the construction torque, repeating the step (3), and sequentially fastening each constant tension bolt pair along the opposite angle by using the constant tension fastening tool; for example, the constant tension bolt pair at the twelve 412 positions of the flange holes can be tightened in a clockwise mode according to 80% of construction torque, then the constant tension bolt pair at the six 406 positions of the flange holes can be tightened according to 80% of construction torque, then the constant tension bolt pair at the first 401 positions of the flange holes can be tightened according to 80% of construction torque, then the constant tension bolt pair at the seven 407 positions of the flange holes can be tightened according to 80% of construction torque, and the process is repeated until all the constant tension bolt pairs are tightened.
Step (6) setting the torque value in the constant tension fastening tool as 100% of the construction torque, and sequentially fastening each constant tension bolt pair along opposite angles by using the constant tension fastening tool; the specific method may be operated as in step (5).
Specifically, in the embodiment, in the process of fastening the constant tension bolt pair, three torque values which are sequentially increased are adopted to pretension each constant tension bolt pair in stages, in the first stage, each constant tension bolt pair is pretensioned synchronously by using a constant tension fastening tool according to 50% of the determined construction torque, and each constant tension bolt pair is fastened synchronously according to an upper direction, a lower direction, a left direction and a right direction, so that each constant tension bolt pair can be fastened gradually, flanges can be closed in parallel in the fastening process, more uniform stress is facilitated, and unbalance loading can be eliminated; the torque value of the constant tension fastening tool is gradually increased in the second stage and the third stage, and the constant tension bolt pairs are fastened in sequence along opposite angles, so that the stress of the flange and the constant tension bolt pairs in the fastening process is more uniform, and the pretightening force of the constant tension bolt pairs can be accurately controlled so as to meet the design requirement.
In a further scheme, in the step (3) and/or the step (4), the number of the adopted constant-tension fastening tools is one pair, two pairs or multiple pairs; the pair of constant-tension fastening tools can respectively act on two studs 101 at the opposite angles of the same flange, the other pair of constant-tension fastening tools can respectively act on two studs 101 at the other opposite angles of the flange, and the pair or two pairs of constant-tension fastening tools are controlled to synchronously act, so that the uniform stress of the flange in the fastening process is facilitated, and the parallel closing of the two flanges is facilitated.
In a more perfect scheme, the method further comprises the step (7) of sequentially fastening each constant tension bolt pair according to the construction torque and the construction control parameters by using the constant tension fastening tool; the fastened constant tension bolt pair can be calibrated through the step, namely, the constant tension bolt pair is fastened by using a constant tension fastening tool according to 100% of construction parameters, and all the constant tension bolt pairs can accurately reach the set pretightening force.
Example 2
The fastening method provided in example 1 is applied to the maintenance fastening practical operation of the heat exchanger of a certain petroleum refinery as follows:
the first step is as follows: technicians communicate with field technicians in an oil refinery, determine the pre-tightening force of the bolt pair to be 205KN according to field process parameters, the stress requirement of a sealing element and the like, and select 160 groups of 8.8-grade constant tension bolt pairs with the diameters of 27mm and the lengths of 220 mm;
the second step is that: performing quality inspection and acceptance on the selected constant tension bolt pair according to relevant standards and specifications;
the third step: an electric constant-tension fastening tool is selected for fastening;
the fourth step: constructing a test system, and installing the selected constant tension bolt pair to the test system;
the fifth step: three components of the constant tension bolt pair with the same specification are selected to be installed on a test system for three times, and fastening operation is carried out on the test system for three times; specifically, the selected electric constant-tension fastening tool is used for fastening in a test, when the tension applied to the stud 101 reaches 205KN, the fastening operation is stopped, and a torque value and control parameters (such as current) of the torque are recorded; and selecting the average value of the three times of test data to determine that the torque value is 1200 N.m and the current is 4A (namely the construction torque is 1200 N.m and the current is 4A), signing, confirming and issuing a construction scheme by testers and technicians (if the error of the three times of test data exceeds the standard, re-testing).
And a sixth step: field installation;
A. checking the flatness of the flange surface to meet the relevant standard;
B. checking the sealing gasket 513 to meet relevant standards;
the seventh step: the flanges 400 are butted and 4 locating pins 500 are inserted.
The eighth step: penetrating the studs 101 into other flange holes, sleeving the snap nuts 102 at one ends of the studs 101, and constructing one end of each snap nut 102 with snap teeth to be in contact with the flange; a snap washer 103 is sleeved at the other end of the stud 101, one end of the snap washer 103, which is provided with snap teeth, is contacted with a flange, and a nut sleeve is arranged at the upper end of the snap washer as shown in fig. 4-9;
the ninth step: by adopting the electric constant tension fastening tool, the set torque value is 50 percent of the construction torque, namely 600 N.m, and the electric constant tension fastening tool is fastened synchronously from top to bottom and from left to right to reach the set torque value (in the operation fastening process, the electric constant tension fastening tool automatically stops working when reaching the set value).
The tenth step: after fastening is finished, setting the torque value of the electric constant tension fastening tool according to 80% of the construction torque, namely 960 N.m, and continuously fastening the constant tension bolt pair, wherein the sequence is as follows: fastening from up and down, left and right synchronously.
The eleventh step: after fastening is finished, setting the torque value of the electric constant tension fastening tool according to 100% of construction torque, namely 1200 N.m, and continuously fastening the constant tension bolt pair, wherein the sequence is as follows: fastening from up and down, left and right synchronously.
The twelfth step: and (5) checking the torque value of the nut, and finishing the fastening operation if all the nut is qualified.
The above description is only for the specific embodiments of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present invention, and all the changes or substitutions should be covered within the scope of the present invention.
Claims (6)
1. An accurate fastening method without unbalance loading and constant tension is characterized by comprising the following steps:
step 1, calculating the pre-tightening force required by a bolt pair according to relevant standards and specifications and flange sealing gasket specifications, and selecting a constant tension bolt pair with corresponding specification grades, wherein the constant tension bolt pair comprises a stud, an occlusion nut, an occlusion washer and a nut, one end of the occlusion nut and one end of the occlusion washer are respectively provided with occlusion teeth, and the radius of the nut is equal to the radius length of the occlusion washer;
step 2, checking and accepting the quality of the selected constant tension bolt pair according to relevant standards and specifications;
step 3, selecting a constant-tension fastening tool meeting the requirements of a fastening operation environment;
step 4, mounting the selected constant tension bolt pair to a test system, wherein the constructed test system comprises a test platform, a flange I, a constant tension fastening tool, a tension collector, a data processor and a display, and the test platform comprises a base and a flange II constructed on the base; the constant-tension fastening tool comprises a fixed end and a power end which are coaxial, the shape of an opening at the lower side of the fixed end is matched with the outer contour of the meshing washer, and the fixed end is used for locking the meshing washer to generate constant reaction moment; the power end is in clearance fit with the fixed end, the shape of an opening at the lower side of the power end is matched with the outer contour of a nut in the constant-tension bolt pair, and the power end is used for driving the nut to rotate under the action of a constant-tension fastening tool; the fixed end does not rotate along with the power end but rotates and is static relative to the surface of a fastened piece; the constant tension fastening tool, the tension collector and the display are respectively connected with the data processor, and the tension collector is used for collecting tension born by the stud in the fastening process of the bolt pair and recording the tension, the torque and the construction control parameters by the data processor; the stud in the constant tension bolt pair sequentially penetrates through the meshing nut, the first flange, the tension collector, the second flange, the meshing washer and the nut in the constant tension bolt pair, one end of the meshing nut with meshing teeth is in contact with the first flange, one end of the meshing washer with meshing teeth is in contact with the second flange, the power end and the fixed end are respectively sleeved on the nut and the meshing washer, and the constant tension fastening tool drives the power end to rotate the nut; in the rotation process of the nut, the occlusion teeth of the occlusion nut and the occlusion washer bite the surface of the fastened piece and keep relative static with the fixed end and the fastened piece;
step 5, fastening operation is carried out on the constant tension bolt pair on the test system by using the selected constant tension fastening tool, in the fastening process, the tension born by the stud, the torque and the control parameter of the constant tension fastening tool are collected by the test system, and when the tension is equal to the pre-tightening force required by the bolt pair, the torque born by the bolt pair at the moment is recorded and is used as the construction torque, the control parameter of the constant tension fastening tool at the moment is recorded and is used as the construction control parameter to compile a construction scheme;
and 6, selecting the constant-tension bolt pair in the step 1, selecting the constant-tension fastening tool in the step 3, and fastening the fastened piece by using the construction scheme compiled in the step 5 on the construction site.
2. The unbiased load constant tension precise fastening method according to claim 1, wherein in the step 1, the bolt pair pre-tightening force is calculated according to design requirements, process parameters, relevant design standards and/or design specifications.
3. The unbiased load constant tension precise fastening method according to claim 1, wherein the above steps 4 to 5 are repeatedly performed three or more times; if the test values obtained by three or more tests meet the technical requirements, compiling a construction scheme according to the test values;
if the test values obtained by three or more tests do not meet the technical requirements, after finding out reasons and correcting, re-executing the steps 4-5 for three or more times, and compiling a construction scheme according to the test values until the obtained test values all meet the technical requirements;
the test values include the construction torque and construction control parameters.
4. The unbiased load constant tension precise fastening method according to claim 3, wherein the average value of the torques among the test values obtained from three or more tests is taken as the construction torque.
5. The unbiased load constant tension precise fastening method according to claim 1, wherein the data processor is a PC, a single chip microcomputer or a universal tester.
6. The unbiased load constant tension precise fastening method according to claim 1, wherein the tension collector adopts a hollow disc-shaped structure so as to be assembled between the first flange and the second flange.
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| SU1139907A1 (en) * | 1983-12-16 | 1985-02-15 | Kravchuk Sergej V | Self-locking nut |
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| CN108150516A (en) * | 2016-12-06 | 2018-06-12 | 上海丞捷机电有限公司 | A kind of locking stretching dynamometry washer |
| EP3427898A1 (en) * | 2017-07-14 | 2019-01-16 | Schaaf GmbH & Co. KG | Fixing system for at least one screw connection |
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| SU1139907A1 (en) * | 1983-12-16 | 1985-02-15 | Kravchuk Sergej V | Self-locking nut |
| CN201720678U (en) * | 2010-07-21 | 2011-01-26 | 凯特克贸易(上海)有限公司 | Multiplex non-offset-load bolt fastener |
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| CN108150516A (en) * | 2016-12-06 | 2018-06-12 | 上海丞捷机电有限公司 | A kind of locking stretching dynamometry washer |
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